79 results on '"Watson LE"'
Search Results
2. Comparison of paracetamol absorption and gastric emptying measured by scintigraphy in relation to rate of appearance of oral glucose and postprandial glycaemia
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Bizzotto, R, Rayner, Ck, Watson, Le, Phillips, Lk, Lange, K, Bound, Mj, Grivell, J, Wu, T, Jones, Kl, Horowitz, M, Ferrannini, E, Trico, D, Frascerra, S, Natali, A, and Mari, A
- Published
- 2020
3. Assessing Mbiotisho: A smartphone application used to collect high‐frequency health and nutrition data from difficult‐to‐reach populations
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Nathaniel Jensen, Watson Lepariyo, Vincent Alulu, Simbarashe Sibanda, and Beatrice N. Kiage
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anthropometry ,cost and cost analysis ,data quality ,digital data collection ,epidemiological methods ,health and nutrition data ,Pediatrics ,RJ1-570 ,Gynecology and obstetrics ,RG1-991 ,Nutritional diseases. Deficiency diseases ,RC620-627 - Abstract
Abstract There is an urgent need for improved and timely health and nutrition data. We developed and tested a smartphone application that caregivers from a pastoral population used to measure, record and submit high‐frequency and longitudinal health and nutrition information on themselves and their children. The data were assessed by comparing caregiver‐submitted measurements of mid–upper arm circumference (MUAC) to several benchmark data sets, including data collected by community health volunteers from the participating caregivers during the project period and data generated by interpreting photographs of MUAC measurements submitted by all participants. We found that the caregivers participated frequently and consistently over the 12‐month period of the project; most of them made several measurements and submissions in at least 48 of the 52 weeks of the project. The evaluation of data quality was sensitive to which data set was used as the benchmark, but the results indicate that the errors in the caregivers' submissions were similar to that of enumerators in other studies. We then compare the costs of this alternative approach to data collection through more conventional methods, concluding that conventional methods can be more cost‐effective for large socioeconomic surveys that value the breadth of the survey over the frequency of data, while the alternative we tested is favoured for those with objectives that are better met by high‐frequency observations of a smaller number of well‐defined outcomes.
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- 2023
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4. Friend of a friend models of network growth
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Watson Levens, Alex Szorkovszky, and David J. T. Sumpter
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networks ,power-laws ,degree distributions ,clustering coefficients ,Science - Abstract
One of the best-known models in network science is preferential attachment. In this model, the probability of attaching to a node depends on the degree of all nodes in the population, and thus depends on global information. In many biological, physical and social systems, however, interactions between individuals depend only on local information. Here, we investigate a truly local model of network formation—based on the idea of a friend of a friend—with the following rule: individuals choose one node at random and link to it with probability p, then they choose a neighbour of that node and link with probability q. Our model produces power-laws with empirical exponents ranging from 1.5 upwards and clustering coefficients ranging from 0 up to 0.5 (consistent with many real networks). For small p and q = 1, the model produces super-hub networks, and we prove that for p = 0 and q = 1, the proportion of non-hubs tends to 1 as the network grows. We show that power-law degree distributions, small world clustering and super-hub networks are all outcomes of this, more general, yet conceptually simple model.
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- 2022
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5. KAZNET: An Open-Source, Micro-Tasking Platform for Remote Locations
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Philemon Chelanga, Francesco Fava, Vincent Alulu, Rupsha Banerjee, Oscar Naibei, Masresha Taye, Matt Berg, Diba Galgallo, Wako Gobu, Watson Lepariyo, Kavoi Muendo, and Nathaniel Jensen
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data collection ,drylands ,pastoralists ,micro-tasking ,open-source ,Nutrition. Foods and food supply ,TX341-641 ,Food processing and manufacture ,TP368-456 - Abstract
Field surveys are the workhorse of social and environmental research, but conventional collection through monitors or enumerators are cost prohibitive in many remote or otherwise difficult settings, which can lead to a poor understanding of those environments and an underrepresentation of the people living in them. In such cases, micro-tasking can offer a promising alternative. By activating in-situ data collectors, micro-tasking avoids many of the large expenses related to conventional field survey processes. In addition to relaxing resource constraints, crowd-sourcing can be flexible and employ data quality protocols unheard-of for conventional methods. This study assesses the potential of using micro-tasking to monitor socioeconomic and environmental indicators in remote settings using a new platform called KAZNET. KAZNET leverages the network of people with smartphones, which are becoming ubiquitous even in the remote rural settings, to execute both long-term and short-term data collection activities, with flexibility to adjust or add tasks in real-time. It also allows for multiple projects, requiring different data types, to be rolled out in the same platform simultaneously. For the data-collector, KAZNET is effectively a wrapper for the commonly used and open source, Open Data Kit (ODK) software, which specializes in offline data collection. A web interface allows administrators to calibrate, deploy, and validate tasks performed by contributors. KAZNET has been used in several projects to collect data in remote pastoral regions of East Africa since its inception in 2017. KAZNET has shown to be effective for collecting high frequency and repeated measures from markets, households and rangelands in remote regions at relatively low cost compared to traditional survey methods. While the successes of micro-tasking are promising, there are clear trade-offs and complementarities between micro-tasking and standard surveys methods, which researchers and practitioners need to consider when implementing either approach.
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- 2022
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6. Albers ve Mirası
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WATSON, Le Clair
- Published
- 2005
7. The relationship between dietary fat intake and risk of colorectal cancer: Evidence from the combined analysis of 13 case-control studies
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Howe, GR Aronson, KJ Benito, E Castelleto, R Cornee, J and Duffy, S Gallagher, RP Iscovich, JM DengAo, J Kaaks, R Kune, GA Kune, S Lee, HP Lee, M Miller, AB and Peters, RK Potter, JD Riboli, E Slattery, ML and Trichopoulos, D Tuyns, A Tzonou, A Watson, LE and Whittemore, AS WuWilliams, AH Shu, Z
- Abstract
The objective of this study was to examine the effects of the intake of dietary fat upon colorectal cancer risk in a combined analysis of data from 13 case-control studies previously conducted in populations with differing colorectal cancer rates and dietary practices. Original data records for 5,287 cases of colorectal cancer and 10,470 controls were combined. Logistic regression analysis was used to estimate odds ratios (OR) for intakes of total energy, total fat and its components, and cholesterol. Positive associations with energy intake were observed for 11 of the 13 studies. However, there was little, if any, evidence of any energy-independent effect of either total fat with ORs of 1.00, 0.95, 1.01, 1.02, and 0.92 for quintiles of residuals of total fat intake (P trend = 0.67) or for saturated fat with ORs of 1.00, 1.08, 1.06, 1.21, and 1.06 (P trend = 0.39). The analysis suggests that, among these case-control studies, there is no energy-independent association between dietary fat intake and risk of colorectal cancer. It also suggests that simple substitution of fat by other sources of calories is unlikely to reduce meaningfully the risk of colorectal cancer.
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- 1997
8. Diterpenoids and Sesquiterpene Lactones from Helianthus tuberosus
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Pan, L, primary, Sinden, M, additional, Kennedy, AH, additional, Chai, H, additional, Watson, LE, additional, Graham, TL, additional, and Kinghorn, AD, additional
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- 2008
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9. Cancer as a 'we-disease': examining the process of coping from a relational perspective.
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Kayser K, Watson LE, and Andrade JT
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This paper presents findings on how breast cancer patients and their partners cope together with the cancer diagnosis and treatment. It expands on earlier frameworks of dyadic coping by presenting a model that views dyadic coping as a process that varies according to how couples appraise the illness- related stress, communicate about it, coordinate their coping efforts, and make meaning from the illness experience. In-depth analyses were conducted on interviews with 10 couples who were coping with breast cancer. A qualitative method that comprises a series of 'listenings' to the couples' experiences was used to examine how couples talked about their stress and coping efforts. Two patterns of relational coping were identified: mutually responsiveness and disengaged avoidance. The relational qualities of relationship awareness, authenticity, and mutuality were identified as important ingredients for dyadic coping. Suggestions for future research that furthers our understanding of relational coping are offered. [ABSTRACT FROM AUTHOR]
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- 2007
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10. The Response of Six Eucalyptus Species and Casuarina obesa to the Combined Effect of Salinity and Waterlogging
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van der Moezel, PG, Watson, LE, Pearce-Pinto, GVN, and Bell, DT
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Seedlings of Eucalyptus camaldulensis, E. comitae-vallis, E. kondininensis, E. lesouefii, E. platycorys, E. spathulata and Casuarina obesa were grown in a glasshouse under non-saline drained, saline drained, non-saline waterlogged, and saline waterlogged conditions for 3 months. Measurements were taken of seedling height, seedling survival and the concentration of Na, K, Ca, Mg and Cl in plant tissues. Production of specialised roots containing aerenchyma in E. camaldulensis and C. obesa enabled these species to tolerate non-saline waterlogged conditions. Saline, but freely drained conditions reduced seedling growth for all species but only E. kondininensis recorded seedling deaths. C. obesa was the species most tolerant of saline waterlogged conditions with no seedling deaths and a lower reduction in growth compared to the Eucalyptus species. Exclusion of Na and Cl, together with the production of specialised roots by C. obesa are suggested as the probable factors relating to the high seedling tolerance in saline waterlogging. The species with highest tolerance to non-saline waterlogging were more tolerant of saline waterlogged conditions. The importance of this result for evaluating trees to be used in the rehabilitation of secondary salinised land in Australia is discussed.
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- 1988
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11. Stimulation of Seed-Germination of Understorey Species of the Northern Jarrah Forest of Western-Australia
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Bell, DT, primary, Vlahos, S, additional, and Watson, LE, additional
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- 1987
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12. The Response of Six Eucalyptus Species and Casuarina obesa to the Combined Effect of Salinity and Waterlogging
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van der Moezel, PG, primary, Watson, LE, additional, Pearce-Pinto, GVN, additional, and Bell, DT, additional
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- 1988
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13. Older adults' attitudes about continuing cancer screening later in life: a pilot study interviewing residents of two continuing care communities
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Walter Louise C, Bynum Debra L, Watson Lea C, Amick Halle R, Kistler Christine E, Lewis Carmen L, and Pignone Michael P
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Geriatrics ,RC952-954.6 - Abstract
Abstract Background Individualized decision making has been recommended for cancer screening decisions in older adults. Because older adults' preferences are central to individualized decisions, we assessed older adults' perspectives about continuing cancer screening later in life. Methods Face to face interviews with 116 residents age 70 or over from two long-term care retirement communities. Interview content included questions about whether participants had discussed cancer screening with their physicians since turning age 70, their attitudes about information important for individualized decisions, and their attitudes about continuing cancer screening later in life. Results Forty-nine percent of participants reported that they had an opportunity to discuss cancer screening with their physician since turning age 70; 89% would have preferred to have had these discussions. Sixty-two percent believed their own life expectancy was not important for decision making, and 48% preferred not to discuss life expectancy. Attitudes about continuing cancer screening were favorable. Most participants reported that they would continue screening throughout their lives and 43% would consider getting screened even if their doctors recommended against it. Only 13% thought that they would not live long enough to benefit from cancer screening tests. Factors important to consider stopping include: age, deteriorating or poor health, concerns about the effectiveness of the tests, and doctors recommendations. Conclusion This select group of older adults held positive attitudes about continuing cancer screening later in life, and many may have had unrealistic expectations. Individualized decision making could help clarify how life expectancy affects the potential survival benefits of cancer screening. Future research is needed to determine whether educating older adults about the importance of longevity in screening decisions would be acceptable, affect older adults' attitudes about screening, or change their screening behavior.
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- 2006
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14. Older adults' beliefs about physician-estimated life expectancy: a cross-sectional survey
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Bynum Debra L, Amick Halle R, Lewis Carmen L, Kistler Christine E, Walter Louise C, and Watson Lea C
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Medicine (General) ,R5-920 - Abstract
Abstract Background Estimates of life expectancy assist physicians and patients in medical decision-making. The time-delayed benefits for many medical treatments make an older adult's life expectancy estimate particularly important for physicians. The purpose of this study is to assess older adults' beliefs about physician-estimated life expectancy. Methods We performed a mixed qualitative-quantitative cross-sectional study in which 116 healthy adults aged 70+ were recruited from two local retirement communities. We interviewed them regarding their beliefs about physician-estimated life expectancy in the context of a larger study on cancer screening beliefs. Semi-structured interviews of 80 minutes average duration were performed in private locations convenient to participants. Demographic characteristics as well as cancer screening beliefs and beliefs about life expectancy were measured. Two independent researchers reviewed the open-ended responses and recorded the most common themes. The research team resolved disagreements by consensus. Results This article reports the life-expectancy results portion of the larger study. The study group (n = 116) was comprised of healthy, well-educated older adults, with almost a third over 85 years old, and none meeting criteria for dementia. Sixty-four percent (n = 73) felt that their physicians could not correctly estimate their life expectancy. Sixty-six percent (n = 75) wanted their physicians to talk with them about their life expectancy. The themes that emerged from our study indicate that discussions of life expectancy could help older adults plan for the future, maintain open communication with their physicians, and provide them knowledge about their medical conditions. Conclusion The majority of the healthy older adults in this study were open to discussions about life expectancy in the context of discussing cancer screening tests, despite awareness that their physicians' estimates could be inaccurate. Since about a third of participants perceived these discussions as not useful or even harmful, physicians should first ascertain patients' preferences before discussing their life expectancies.
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- 2006
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15. Title: Differentiating the effects of whey protein and guar gum preloads on postprandial glycemia in type 2 diabetes
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Linda E. Watson, Helen L. Checklin, Liza K. Phillips, Tongzhi Wu, Christopher K. Rayner, Michelle J. Bound, Jacqueline Grivell, Karen L. Jones, Michael Horowitz, Watson, LE, Phillips, LK, Wu, T, Bound, MJ, Checklin, H, Grivell, J, Jones, KL, Horowitz, M, and Rayner, CK
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Blood Glucose ,Male ,0301 basic medicine ,medicine.medical_specialty ,Whey protein ,medicine.medical_treatment ,Guar ,Blood sugar ,030209 endocrinology & metabolism ,type-2 diabetes ,Type 2 diabetes ,Critical Care and Intensive Care Medicine ,Galactans ,Mannans ,03 medical and health sciences ,gastric emptying ,0302 clinical medicine ,incretin hormones ,Internal medicine ,Plant Gums ,medicine ,Humans ,Insulin ,Guar gum ,Aged ,030109 nutrition & dietetics ,Nutrition and Dietetics ,Gastric emptying ,business.industry ,digestive, oral, and skin physiology ,food and beverages ,whey protein ,Postprandial Period ,postprandial glycemia ,medicine.disease ,Whey Proteins ,Postprandial ,Endocrinology ,Diabetes Mellitus, Type 2 ,Gastric Emptying ,Glycemic Index ,Female ,business - Abstract
Background and aims: Whey protein and guar gum have both been reported to reduce postprandial glycemia in health and type 2 diabetes, associated with stimulation of glucagon-like peptide-1 (GLP-1) and/or slowing of gastric emptying. Our aim was to evaluate, in type 2 diabetes, the acute effects of low dose “preloads” of whey and guar, given alone or in combination before a meal, on postprandial glycemia, insulin, GLP-1, and gastric emptying. Methods: 21 patients with type 2 diabetes, managed by diet or metformin alone, were each studied on 4 days. They received a preload “shake” 15min before a mashed potato meal (368.5 kcal) labeled with 13C-octanoic-acid. The preloads comprised either (i) 17 g whey (W), (ii) 5 g guar (G), (iii) 17 g whey + 5 g guar (WG) each sweetened with 60 mg sucralose, and (iv) 60 mg sucralose alone (control; C), all dissolved in 150 mL water. Venous blood was sampled frequently for measurements of glucose, insulin, and GLP-1 concentrations. Gastric half-emptying time (T50) was calculated from breath 13CO2 excretion over 240 min. Results: Postprandial blood glucose concentrations were lower with W and WG compared to C (each P < 0.0001, treatment × time interaction), and lower after G than C only at 30min. Insulin, GLP-1, and glucagon concentrations were higher after W than WG, G, or C (P < 0.05, treatment × time interaction), without differences between the latter three. Gastric emptying was slower with W (T50: 179.6 ± 6.1 min, P < 0.05) and WG (T50: 197.6 ± 9.7 min, P < 0.0001) when compared to C (T50: 162.9 ± 6.2 min), but did not differ between G (T50: 171.3 ± 7.0) and C (P > 0.99). Conclusion: Both whey and whey/guar preloads reduced postprandial glycemia, associated with slowing of gastric emptying. Low dose guar was less effective as a preload for glucose-lowering and did not slow gastric emptying usc Refereed/Peer-reviewed
- Published
- 2019
16. Gastric Emptying in Patients With Well-Controlled Type 2 Diabetes Compared With Young and Older Control Subjects Without Diabetes
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Xuyi Wang, Liza K. Phillips, Tongzhi Wu, Cong Xie, Karen L. Jones, Linda E. Watson, Zilin Sun, Ziyi Li, Christopher K. Rayner, Michael Horowitz, Watson, LE, Xie, Cong, Wang, Xuyi, Li, Ziyi, Phillips, Liza K, Sun, Zilin, Jones, Karen L, Horowitz, Michael, Rayner, Christopher K, and Wu, Tongzhi
- Subjects
Adult ,Male ,medicine.medical_specialty ,Aging ,endocrine system diseases ,Adolescent ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,030209 endocrinology & metabolism ,Context (language use) ,Type 2 diabetes ,030204 cardiovascular system & hematology ,Biochemistry ,Gastroenterology ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Endocrinology ,Internal medicine ,Diabetes mellitus ,Diet, Diabetic ,medicine ,Humans ,Hypoglycemic Agents ,Glycemic ,Aged ,Breath test ,diabetes ,Gastric emptying ,medicine.diagnostic_test ,business.industry ,digestive, oral, and skin physiology ,Biochemistry (medical) ,Age Factors ,nutritional and metabolic diseases ,Type 2 Diabetes Mellitus ,Middle Aged ,medicine.disease ,Postprandial Period ,Metformin ,Postprandial ,Diabetes Mellitus, Type 2 ,Gastric Emptying ,Female ,Independent Living ,business - Abstract
Context Gastric emptying is a major determinant of postprandial glycemia and is often delayed in long-standing, complicated type 2 diabetes mellitus (T2DM). However, there is little information about gastric emptying in well-controlled T2DM. Objective To evaluate the rate of gastric emptying in community-based patients with relatively well-controlled T2DM compared with young and older control subjects without diabetes. Participants and Design A total of 111 patients with T2DM managed by diet (n = 52) or metformin monotherapy (n = 59) (HbA1c 6.6 ± 0.1%/49.0 ± 0.9 mmol/mol), 18 age- and body mass index (BMI)-matched older subjects without diabetes, and 15 young healthy subjects consumed a standardized mashed potato meal (368.5 kcal) containing 100 μL 13 C-octanoic acid. Gastric emptying (by breath test) and blood glucose were evaluated over 240 minutes. Results Gastric emptying was slower in the older than in the young subjects without diabetes (2.3 ± 0.1 vs 3.0 ± 0.1 kcal/min, P = 0.0008). However, relative to the age- and BMI-matched subjects without diabetes, gastric emptying (2.8 ± 0.1 kcal/min) was faster in patients with T2DM (P = 0.0005). Furthermore, gastric emptying was faster in the metformin-treated (3.0 ± 0.1 kcal/min) than in the diet-controlled (2.7 ± 0.1 kcal/min) patients with T2DM (P = 0.011), although there were no differences in age, BMI, HbA1c, or the duration of known diabetes. The increments in blood glucose (at t = 30 and 60 minutes and the incremental area under the curve during t = 0 to 120 minutes) after the meal were related directly to the rate of gastric emptying in the subjects with T2DM regardless of treatment with or without metformin (P < 0.05 each). Conclusions Gastric emptying is slowed with aging but otherwise is relatively more rapid in patients with well-controlled T2DM. This provides a strong rationale for slowing gastric emptying to improve postprandial glycemic control in these patients. usc Refereed/Peer-reviewed
- Published
- 2018
17. Gastric emptying during and following resolution of moderate diabetic ketoacidosis in type 1 diabetes: a case series.
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Jalleh RJ, Phillips L, Umapathysivam MM, Jones KL, Marathe CS, Watson LE, Bound M, Rayner CK, and Horowitz M
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- Humans, Adolescent, Young Adult, Adult, Gastric Emptying, Glycated Hemoglobin, Diabetes Mellitus, Type 1 complications, Gastroparesis, Diabetic Ketoacidosis
- Abstract
Introduction: To use the 'gold standard' technique of scintigraphy to quantify gastric emptying (GE) as soon as practicable during an admission with diabetic ketoacidosis (DKA) and following its resolution at least 7 days later., Research Design and Methods: Five patients with type 1 diabetes, age 29±12 years; Body Mass Index 23±3 kg/m
2 ; hemoglobin A1c 11.3%±1.9%, were studied during an admission with DKA and following its resolution. Solid and liquid GE were measured using scintigraphy. Solid emptying was assessed via the percentage intragastric retention at 100 min and that of liquid by the 50% emptying time., Results: There was no difference in either solid or liquid GE at the initial study compared with the follow-up. Median (IQR) solid retention was 47±20 versus 38%±33%, respectively; p=0.31, and time to empty 50% of liquid was 37±25 min versus 35±15 min, p=0.31, at the initial and follow-up GE study, respectively., Conclusions: GE of solids and liquids is not affected by moderate DKA, inferring that earlier reintroduction of oral intake may be appropriate., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)- Published
- 2024
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18. Myocardial deformation imaging by 2D speckle tracking echocardiography for assessment of diastolic dysfunction in murine cardiopathology.
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Daniels LJ, Macindoe C, Koutsifeli P, Annandale M, James SL, Watson LE, Coffey S, Raaijmakers AJA, Weeks KL, Bell JR, Janssens JV, Curl CL, Delbridge LMD, and Mellor KM
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- Male, Animals, Mice, Stroke Volume, Echocardiography methods, Myocardium, Ventricular Function, Left, Heart Failure, Diabetes Mellitus, Type 2 complications, Diabetes Mellitus, Type 2 diagnostic imaging, Ventricular Dysfunction, Left diagnostic imaging
- Abstract
Diastolic dysfunction is increasingly identified as a key, early onset subclinical condition characterizing cardiopathologies of rising prevalence, including diabetic heart disease and heart failure with preserved ejection fraction (HFpEF). Diastolic dysfunction characterization has important prognostic value in management of disease outcomes. Validated tools for in vivo monitoring of diastolic function in rodent models of diabetes are required for progress in pre-clinical cardiology studies. 2D speckle tracking echocardiography has emerged as a powerful tool for evaluating cardiac wall deformation throughout the cardiac cycle. The aim of this study was to examine the applicability of 2D speckle tracking echocardiography for comprehensive global and regional assessment of diastolic function in a pre-clinical murine model of cardio-metabolic disease. Type 2 diabetes (T2D) was induced in C57Bl/6 male mice using a high fat high sugar dietary intervention for 20 weeks. Significant impairment in left ventricle peak diastolic strain rate was evident in longitudinal, radial and circumferential planes in T2D mice. Peak diastolic velocity was similarly impaired in the longitudinal and radial planes. Regional analysis of longitudinal peak diastolic strain rate revealed that the anterior free left ventricular wall is particularly susceptible to T2D-induced diastolic dysfunction. These findings provide a significant advance on characterization of diastolic dysfunction in a pre-clinical mouse model of cardiopathology and offer a comprehensive suite of benchmark values for future pre-clinical cardiology studies., (© 2023. The Author(s).)
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- 2023
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19. Determinants of blood glucose concentrations following a high carbohydrate meal in type 2 diabetes: A multiple linear regression analysis.
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Xie C, Jalleh RJ, Watson LE, Huang W, Sun Y, Jones KL, Horowitz M, Rayner CK, and Wu T
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- Humans, Insulin, Blood Glucose analysis, Regression Analysis, Gastric Emptying, Postprandial Period, Glucagon, Diabetes Mellitus, Type 2
- Abstract
This study showed that in relatively well-controlled type 2 diabetes blood glucose levels after a high carbohydrate meal were associated positively with fasting blood glucose, but also positively with gastric emptying in the first hour and negatively with the increments in plasma glucagon-like peptide-1 (GLP-1) in the later postprandial phase., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: KLJ has received research funding from Sanofi, AstraZeneca and drug supplies from Merck Sharp & Dohme. MH has participated in the advisory boards and/or symposia for Novo Nordisk, Sanofi, Novartis, Eli Lilly, Merck Sharp & Dohme, Boehringer Ingelheim, and AstraZeneca and has received honoraria for this activity. CKR has received research funding from AstraZeneca, Merck Sharp & Dohme, Eli Lilly, Novartis, and Sanofi. TW has received travel support from Novartis and Sanofi and research funding from Novartis and AstraZeneca. None of the other authors has any personal or financial conflict of interest to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)
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- 2023
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20. Plasma GLP-1 Response to Oral and Intraduodenal Nutrients in Health and Type 2 Diabetes-Impact on Gastric Emptying.
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Xie C, Huang W, Watson LE, Soenen S, Young RL, Jones KL, Horowitz M, Rayner CK, and Wu T
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- Blood Glucose metabolism, Gastric Emptying physiology, Glucose, Humans, Insulin metabolism, Nutrients, Postprandial Period, Diabetes Mellitus, Type 2, Glucagon-Like Peptide 1 metabolism
- Abstract
Context: Both gastric emptying and the secretion of glucagon-like peptide-1 (GLP-1) are major determinants of postprandial glycemia in health and type 2 diabetes (T2D). GLP-1 secretion after a meal is dependent on the entry of nutrients into the small intestine, which, in turn, slows gastric emptying., Objective: To define the relationship between gastric emptying and the GLP-1 response to both oral and small intestinal nutrients in subjects with and without T2D., Methods: We evaluated: (i) the relationship between gastric emptying (breath test) and postprandial GLP-1 levels after a mashed potato meal in 73 individuals with T2D; (ii) inter-individual variations in GLP-1 response to (a) intraduodenal glucose (4 kcal/min) during euglycemia and hyperglycemia in 11 healthy and 12 T2D, subjects, (b) intraduodenal fat (2 kcal/min) in 15 T2D subjects, and (c) intraduodenal protein (3 kcal/min) in 10 healthy subjects; and (iii) the relationship between gastric emptying (breath test) of 75 g oral glucose and the GLP-1 response to intraduodenal glucose (4 kcal/min) in 21 subjects (9 healthy, 12 T2D)., Results: The GLP-1 response to the mashed potato meal was unrelated to the gastric half-emptying time (T50). The GLP-1 responses to intraduodenal glucose, fat, and protein varied substantially between individuals, but intra-individual variation to glucose was modest. The T50 of oral glucose was related directly to the GLP-1 response to intraduodenal glucose (r = 0.65, P = 0.002)., Conclusion: In a given individual, gastric emptying is not a determinant of the postprandial GLP-1 response. However, the intrinsic gastric emptying rate is determined in part by the responsiveness of GLP-1 to intestinal nutrients., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
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- 2022
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21. Erratum. Effects of Sustained Treatment With Lixisenatide on Gastric Emptying and Postprandial Glucose Metabolism in Type 2 Diabetes: A Randomized Controlled Trial. Diabetes Care 2020;43:1813-1821.
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Rayner CK, Watson LE, Phillips LK, Lange K, Bound MJ, Grivell J, Wu T, Jones KL, Horowitz M, Ferrannini E, Tricò D, Frascerra S, Mari A, and Natali A
- Published
- 2021
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22. Effects of Sustained Treatment With Lixisenatide on Gastric Emptying and Postprandial Glucose Metabolism in Type 2 Diabetes: A Randomized Controlled Trial.
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Rayner CK, Watson LE, Phillips LK, Lange K, Bound MJ, Grivell J, Wu T, Jones KL, Horowitz M, Ferrannini E, Tricò D, Frascerra S, Mari A, and Natali A
- Subjects
- Aged, Australia, Blood Glucose drug effects, Diabetes Mellitus, Type 2 metabolism, Diabetes Mellitus, Type 2 physiopathology, Double-Blind Method, Drug Administration Schedule, Female, Glucagon blood, Humans, Hypoglycemic Agents therapeutic use, Insulin blood, Male, Middle Aged, Peptides administration & dosage, Placebos, Time Factors, Blood Glucose metabolism, Diabetes Mellitus, Type 2 drug therapy, Gastric Emptying drug effects, Peptides pharmacology, Postprandial Period drug effects
- Abstract
Objective: Tachyphylaxis for slowing of gastric emptying is seen with continuous exposure to glucagon-like peptide 1 (GLP-1). We therefore aimed to establish whether prolonged use of a "short-acting" GLP-1 receptor agonist, lixisenatide, achieves sustained slowing of gastric emptying and reduction in postprandial glycemia., Research Design and Methods: A total of 30 patients with metformin-treated type 2 diabetes underwent assessment of gastric emptying (scintigraphy) and glucose metabolism (dual tracer technique) after a 75-g glucose drink, before and after 8 weeks' treatment with lixisenatide (20 μg subcutaneously daily) or placebo, in a double-blind randomized parallel design., Results: Gastric retention of the glucose drink was markedly increased after lixisenatide versus placebo (ratio of adjusted geometric means for area under the curve [AUC] over 240 min of 2.19 [95% CI 1.82, 2.64], P < 0.001), associated with substantial reductions in the rate of systemic appearance of oral glucose ( P < 0.001) and incremental AUC for blood glucose ( P < 0.001). Lixisenatide suppressed both glucagon ( P = 0.003) and insulin ( P = 0.032), but not endogenous glucose production, over 120 min after oral glucose intake. Postprandial glucose lowering over 240 min was strongly related to the magnitude of slowing of gastric emptying by lixisenatide ( r = -0.74, P = 0.002) and to the baseline rate of emptying ( r = 0.52, P = 0.048) but unrelated to β-cell function (assessed by β-cell glucose sensitivity)., Conclusions: Eight weeks' treatment with lixisenatide is associated with sustained slowing of gastric emptying and marked reductions in postprandial glycemia and appearance of ingested glucose. Short-acting GLP-1 receptor agonists therefore potentially represent an effective long-term therapy for specifically targeting postprandial glucose excursions., (© 2020 by the American Diabetes Association.)
- Published
- 2020
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23. Title: Differentiating the effects of whey protein and guar gum preloads on postprandial glycemia in type 2 diabetes.
- Author
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Watson LE, Phillips LK, Wu T, Bound MJ, Checklin H, Grivell J, Jones KL, Horowitz M, and Rayner CK
- Subjects
- Aged, Blood Glucose drug effects, Female, Galactans administration & dosage, Gastric Emptying drug effects, Humans, Insulin blood, Male, Mannans administration & dosage, Plant Gums administration & dosage, Whey Proteins administration & dosage, Diabetes Mellitus, Type 2 blood, Galactans blood, Galactans pharmacology, Glycemic Index drug effects, Mannans blood, Mannans pharmacology, Plant Gums blood, Plant Gums pharmacology, Postprandial Period, Whey Proteins blood, Whey Proteins pharmacology
- Abstract
Background and Aims: Whey protein and guar gum have both been reported to reduce postprandial glycemia in health and type 2 diabetes, associated with stimulation of glucagon-like peptide-1 (GLP-1) and/or slowing of gastric emptying. Our aim was to evaluate, in type 2 diabetes, the acute effects of low dose "preloads" of whey and guar, given alone or in combination before a meal, on postprandial glycemia, insulin, GLP-1, and gastric emptying., Methods: 21 patients with type 2 diabetes, managed by diet or metformin alone, were each studied on 4 days. They received a preload "shake" 15min before a mashed potato meal (368.5 kcal) labeled with
13 C-octanoic-acid. The preloads comprised either (i) 17 g whey (W), (ii) 5 g guar (G), (iii) 17 g whey + 5 g guar (WG) each sweetened with 60 mg sucralose, and (iv) 60 mg sucralose alone (control; C), all dissolved in 150 mL water. Venous blood was sampled frequently for measurements of glucose, insulin, and GLP-1 concentrations. Gastric half-emptying time (T50) was calculated from breath13 CO2 excretion over 240 min., Results: Postprandial blood glucose concentrations were lower with W and WG compared to C (each P < 0.0001, treatment × time interaction), and lower after G than C only at 30min. Insulin, GLP-1, and glucagon concentrations were higher after W than WG, G, or C (P < 0.05, treatment × time interaction), without differences between the latter three. Gastric emptying was slower with W (T50: 179.6 ± 6.1 min, P < 0.05) and WG (T50: 197.6 ± 9.7 min, P < 0.0001) when compared to C (T50: 162.9 ± 6.2 min), but did not differ between G (T50: 171.3 ± 7.0) and C (P > 0.99)., Conclusion: Both whey and whey/guar preloads reduced postprandial glycemia, associated with slowing of gastric emptying. Low dose guar was less effective as a preload for glucose-lowering and did not slow gastric emptying., Clinical Trial Registry Number and Website: Australian and New Zealand Clinical Trials Registry, Trial ID ACTRN12615001272583, http://www.anzctr.org.au., (Copyright © 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)- Published
- 2019
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24. An empirical assessment of a single family-wide hybrid capture locus set at multiple evolutionary timescales in Asteraceae.
- Author
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Jones KE, Fér T, Schmickl RE, Dikow RB, Funk VA, Herrando-Moraira S, Johnston PR, Kilian N, Siniscalchi CM, Susanna A, Slovák M, Thapa R, Watson LE, and Mandel JR
- Abstract
Premise: Hybrid capture with high-throughput sequencing (Hyb-Seq) is a powerful tool for evolutionary studies. The applicability of an Asteraceae family-specific Hyb-Seq probe set and the outcomes of different phylogenetic analyses are investigated here., Methods: Hyb-Seq data from 112 Asteraceae samples were organized into groups at different taxonomic levels (tribe, genus, and species). For each group, data sets of non-paralogous loci were built and proportions of parsimony informative characters estimated. The impacts of analyzing alternative data sets, removing long branches, and type of analysis on tree resolution and inferred topologies were investigated in tribe Cichorieae., Results: Alignments of the Asteraceae family-wide Hyb-Seq locus set were parsimony informative at all taxonomic levels. Levels of resolution and topologies inferred at shallower nodes differed depending on the locus data set and the type of analysis, and were affected by the presence of long branches., Discussion: The approach used to build a Hyb-Seq locus data set influenced resolution and topologies inferred in phylogenetic analyses. Removal of long branches improved the reliability of topological inferences in maximum likelihood analyses. The Astereaceae Hyb-Seq probe set is applicable at multiple taxonomic depths, which demonstrates that probe sets do not necessarily need to be lineage-specific., (© 2019 Jones et al. Applications in Plant Sciences is published by Wiley Periodicals, Inc. on behalf of the Botanical Society of America.)
- Published
- 2019
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25. Gastric Emptying in Patients With Well-Controlled Type 2 Diabetes Compared With Young and Older Control Subjects Without Diabetes.
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Watson LE, Xie C, Wang X, Li Z, Phillips LK, Sun Z, Jones KL, Horowitz M, Rayner CK, and Wu T
- Subjects
- Adolescent, Adult, Age Factors, Aged, Aging physiology, Diabetes Mellitus, Type 2 therapy, Female, Humans, Independent Living, Male, Middle Aged, Postprandial Period, Young Adult, Diabetes Mellitus, Type 2 physiopathology, Diet, Diabetic, Gastric Emptying physiology, Hypoglycemic Agents therapeutic use, Metformin therapeutic use
- Abstract
Context: Gastric emptying is a major determinant of postprandial glycemia and is often delayed in long-standing, complicated type 2 diabetes mellitus (T2DM). However, there is little information about gastric emptying in well-controlled T2DM., Objective: To evaluate the rate of gastric emptying in community-based patients with relatively well-controlled T2DM compared with young and older control subjects without diabetes., Participants and Design: A total of 111 patients with T2DM managed by diet (n = 52) or metformin monotherapy (n = 59) (HbA1c 6.6 ± 0.1%/49.0 ± 0.9 mmol/mol), 18 age- and body mass index (BMI)-matched older subjects without diabetes, and 15 young healthy subjects consumed a standardized mashed potato meal (368.5 kcal) containing 100 μL 13C-octanoic acid. Gastric emptying (by breath test) and blood glucose were evaluated over 240 minutes., Results: Gastric emptying was slower in the older than in the young subjects without diabetes (2.3 ± 0.1 vs 3.0 ± 0.1 kcal/min, P = 0.0008). However, relative to the age- and BMI-matched subjects without diabetes, gastric emptying (2.8 ± 0.1 kcal/min) was faster in patients with T2DM (P = 0.0005). Furthermore, gastric emptying was faster in the metformin-treated (3.0 ± 0.1 kcal/min) than in the diet-controlled (2.7 ± 0.1 kcal/min) patients with T2DM (P = 0.011), although there were no differences in age, BMI, HbA1c, or the duration of known diabetes. The increments in blood glucose (at t = 30 and 60 minutes and the incremental area under the curve during t = 0 to 120 minutes) after the meal were related directly to the rate of gastric emptying in the subjects with T2DM regardless of treatment with or without metformin (P < 0.05 each)., Conclusions: Gastric emptying is slowed with aging but otherwise is relatively more rapid in patients with well-controlled T2DM. This provides a strong rationale for slowing gastric emptying to improve postprandial glycemic control in these patients., (Copyright © 2019 Endocrine Society.)
- Published
- 2019
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26. Longitudinal evaluation of gastric emptying in type 2 diabetes.
- Author
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Watson LE, Phillips LK, Wu T, Bound MJ, Jones KL, Horowitz M, and Rayner CK
- Subjects
- Aged, Blood Glucose analysis, Diabetes Complications diagnosis, Diabetes Mellitus, Type 2 physiopathology, Diabetic Neuropathies diagnosis, Female, Gastrointestinal Diseases diagnosis, Glycated Hemoglobin analysis, Humans, Hyperglycemia diagnosis, Hypoglycemia diagnosis, Insulin analysis, Longitudinal Studies, Male, Middle Aged, Prognosis, Diabetes Complications etiology, Diabetes Mellitus, Type 2 complications, Diabetic Neuropathies etiology, Gastric Emptying, Gastrointestinal Diseases etiology, Hyperglycemia etiology, Hypoglycemia etiology
- Abstract
Aims: To evaluate the natural history of gastric emptying in type 2 diabetes., Methods: 12 patients with type 2 diabetes (7 female; age 65.6 ± 1.2 years; duration of known diabetes 22.9 ± 1.5 years) were invited to return for repeat measurements of gastric emptying using the same dual-labelled solid and liquid meal, a mean of 14.0 ± 0.5 years after their initial study. Blood glucose levels, glycated haemoglobin, upper gastrointestinal symptoms and autonomic nerve function at baseline and follow up were also compared., Results: Gastric emptying of solids was more rapid at follow up than at baseline (period effect P < 0.05), while emptying of liquids was comparable at baseline and follow up (period effect P = 0.2). Gastric emptying of the solid component was abnormally slow (based on T100min) in 6 subjects at baseline and 1 subject at follow up. Liquid emptying was abnormally slow in 6 subjects at baseline, and 5 subjects at follow up. Two patients were insulin treated at baseline, and 6 at follow up. HbA1c was higher at follow up (P < 0.05); however, fasting blood glucose (P = 0.6), postprandial blood glucose excursions (P = 0.07), autonomic nerve function (P > 0.999), and total upper gastrointestinal symptom score (P = 0.1) did not differ., Conclusions: In patients with long-term type 2 diabetes, gastric emptying of solids and liquids does not usually become more delayed over time, and abnormally slow gastric emptying of solids may improve., (Copyright © 2019 Elsevier B.V. All rights reserved.)
- Published
- 2019
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27. A fully resolved backbone phylogeny reveals numerous dispersals and explosive diversifications throughout the history of Asteraceae.
- Author
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Mandel JR, Dikow RB, Siniscalchi CM, Thapa R, Watson LE, and Funk VA
- Subjects
- Africa, Asia, Asteraceae classification, Magnoliopsida genetics, North America, South America, Asteraceae genetics, Biological Evolution, Genome, Plant genetics, Phylogeny
- Abstract
The sunflower family, Asteraceae, comprises 10% of all flowering plant species and displays an incredible diversity of form. Asteraceae are clearly monophyletic, yet resolving phylogenetic relationships within the family has proven difficult, hindering our ability to understand its origin and diversification. Recent molecular clock dating has suggested a Cretaceous origin, but the lack of deep sampling of many genes and representative taxa from across the family has impeded the resolution of migration routes and diversifications that led to its global distribution and tremendous diversity. Here we use genomic data from 256 terminals to estimate evolutionary relationships, timing of diversification(s), and biogeographic patterns. Our study places the origin of Asteraceae at ∼83 MYA in the late Cretaceous and reveals that the family underwent a series of explosive radiations during the Eocene which were accompanied by accelerations in diversification rates. The lineages that gave rise to nearly 95% of extant species originated and began diversifying during the middle Eocene, coincident with the ensuing marked cooling during this period. Phylogenetic and biogeographic analyses support a South American origin of the family with subsequent dispersals into North America and then to Asia and Africa, later followed by multiple worldwide dispersals in many directions. The rapid mid-Eocene diversification is aligned with the biogeographic range shift to Africa where many of the modern-day tribes appear to have originated. Our robust phylogeny provides a framework for future studies aimed at understanding the role of the macroevolutionary patterns and processes that generated the enormous species diversity of Asteraceae., Competing Interests: The authors declare no conflict of interest., (Copyright © 2019 the Author(s). Published by PNAS.)
- Published
- 2019
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28. A whey/guar "preload" improves postprandial glycaemia and glycated haemoglobin levels in type 2 diabetes: A 12-week, single-blind, randomized, placebo-controlled trial.
- Author
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Watson LE, Phillips LK, Wu T, Bound MJ, Checklin HL, Grivell J, Jones KL, Clifton PM, Horowitz M, and Rayner CK
- Subjects
- Aged, Body Composition, Body Weight, Diabetes Mellitus, Type 2 metabolism, Diet, Diabetic, Energy Intake, Female, Glucagon metabolism, Glucagon-Like Peptide 1 metabolism, Humans, Hypoglycemic Agents therapeutic use, Insulin metabolism, Male, Metformin therapeutic use, Middle Aged, Single-Blind Method, Blood Glucose metabolism, Diabetes Mellitus, Type 2 therapy, Galactans therapeutic use, Gastric Emptying, Glycated Hemoglobin metabolism, Mannans therapeutic use, Plant Gums therapeutic use, Postprandial Period, Whey Proteins therapeutic use
- Abstract
Aims: To evaluate the effects of 12 weeks of treatment with a whey/guar preload on gastric emptying, postprandial glycaemia and glycated haemoglobin (HbA1c) levels in people with type 2 diabetes (T2DM)., Materials and Methods: A total of 79 people with T2DM, managed on diet or metformin (HbA1c 49 ± 0.7 mmol/mol [6.6 ± 0.1%]), were randomized, in single-blind fashion, to receive 150 mL flavoured preloads, containing either 17 g whey protein plus 5 g guar (n = 37) or flavoured placebo (n = 42), 15 minutes before two meals, each day for 12 weeks. Blood glucose and gastric emptying (breath test) were measured before and after a mashed potato meal at baseline (without preload), and after the preload at the beginning (week 1) and end (week 12) of treatment. HbA1c levels, energy intake, weight and body composition were also evaluated., Results: Gastric emptying was slower (P < 0.01) and postprandial blood glucose levels lower (P < 0.05) with the whey/guar preload compared to placebo preload, and the magnitude of reduction in glycaemia was related to the rate of gastric emptying at both week 1 (r = -0.54, P < 0.001) and week 12 (r = -0.54, P < 0.0001). At the end of treatment, there was a 1 mmol/mol [0.1%] reduction in HbA1c in the whey/guar group compared to the placebo group (49 ± 1.0 mmol/mol [6.6 ± 0.05%] vs. 50 ± 0.8 mmol/mol [6.7 ± 0.05%]; P < 0.05). There were no differences in energy intake, body weight, or lean or fat mass between the groups., Conclusions: In patients with well-controlled T2DM, 12 weeks' treatment with a low-dose whey/guar preload, taken twice daily before meals, had sustained effects of slowing gastric emptying and reducing postprandial blood glucose, which were associated with a modest reduction in HbA1c, without causing weight gain., (© 2018 John Wiley & Sons Ltd.)
- Published
- 2019
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29. Elastic Modulus Maturation Effect on Shrinkage Stress in a Primary Molar Restored with Tooth-Colored Materials.
- Author
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Suiter EA, Tantbirojn D, Watson LE, Yazdi H, and Versluis A
- Subjects
- Compomers, Composite Resins, Dental Restoration, Permanent methods, Finite Element Analysis, Glass Ionomer Cements, Humans, Polymerization, Dental Materials, Dental Restoration, Permanent instrumentation, Dental Stress Analysis, Elastic Modulus physiology, Molar surgery, Tooth, Deciduous surgery
- Abstract
Purpose: Polymerization shrinkage stress is determined by shrinkage as well as elastic modulus. Elastic modulus develops during polymerization. This study evaluated how elastic modulus affects shrinkage stresses in a primary molar for three types of restorative materials. Methods: Elastic modulus of resin composite, compomers, and resin-modified glass ionomer (RMGI) were determined using four-point bending of rectangular beams at 10 minutes, 24 hours, and after one to four weeks storage in water (n equals 10). Results were analyzed using twoway analysis of variance and pairwise comparisons (α equals 0.05). The elastic moduli were used with published shrinkage data to calculate stresses at the tooth-restoration interface in finite element models of a cross-sectioned restored primary molar. Results: The elastic modulus ranged between 5.6 to 19.9 gigapascal. Elastic modulus values were lowest at 10 minutes, regardless of material, and increased significantly (43 to 95 percent) in 24 hours; RMGI continued to increase (64 percent) for one week. Shrinkage stresses increased nonproportionally (resin composite 31 percent, compomer 35 percent, RMGI 52 percent) with increasing elastic modulus for sustained volumetric shrinkage. Conclusions: Elastic modulus development is material dependent and an important factor in polymerization shrinkage stress. Maturation of restorative materials can cause long-lasting stress increases if shrinkage is not alleviated by hygroscopic expansion.
- Published
- 2018
30. Comparative effects of intraduodenal fat and glucose on the gut-incretin axis in healthy males.
- Author
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Wu T, Rayner CK, Watson LE, Jones KL, Horowitz M, and Little TJ
- Subjects
- Adult, Blood Glucose drug effects, Gastric Inhibitory Polypeptide administration & dosage, Gastric Inhibitory Polypeptide metabolism, Glucagon blood, Glucagon-Like Peptide 1 blood, Glucose administration & dosage, Healthy Volunteers, Humans, Incretins blood, Insulin metabolism, Insulin Secretion, Male, Postprandial Period, Duodenum metabolism, Gastrointestinal Hormones blood, Insulin blood, Intestine, Small metabolism
- Abstract
Background: The interaction of nutrients with the small intestine stimulates the secretion of numerous enteroendocrine hormones that regulate postprandial metabolism. However, differences in gastrointestinal hormonal responses between the macronutrients are incompletely understood. In the present study, we compared blood glucose and plasma hormone concentrations in response to standardised intraduodenal (ID) fat and glucose infusions in healthy humans., Methods: In a parallel study design, 16 healthy males who received an intraduodenal fat infusion were compared with 12 healthy males who received intraduodenal glucose, both at a rate of 2kcal/min over 120min. Venous blood was sampled at frequent intervals for measurements of blood glucose, and plasma total and active glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), insulin and glucagon., Results: Plasma concentrations of the incretin hormones (both total and active GLP-1 and GIP) and glucagon were higher, and plasma insulin and blood glucose concentrations lower, during intraduodenal fat, when compared with intraduodenal glucose, infusion (treatment by time interaction: P<0.001 for each)., Conclusions: Compared with glucose, intraduodenal fat elicits substantially greater GLP-1, GIP and glucagon secretion, with minimal effects on blood glucose or plasma insulin in healthy humans. These observations are consistent with the concept that fat is a more potent stimulus of the 'gut-incretin' axis than carbohydrate., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2017
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31. Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion.
- Author
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Suiter EA, Watson LE, Tantbirojn D, Lou JS, and Versluis A
- Subjects
- Coloring Agents, Compomers chemistry, Composite Resins chemistry, Dental Cavity Preparation classification, Dental Marginal Adaptation, Gels, Glass Ionomer Cements chemistry, Humans, Light-Curing of Dental Adhesives instrumentation, Materials Testing, Optical Imaging instrumentation, Pliability, Polymerization, Resin Cements chemistry, Stress, Mechanical, Surface Properties, Time Factors, Tooth Crown anatomy & histology, Water chemistry, Wettability, Dental Materials chemistry
- Abstract
The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n= 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n= 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n= 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (-6.4 µm) than with the other materials (-12.1 to -14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic expansion was more effective in compensating shrinkage stress than would be assumed based on total shrinkage, because only post-gel shrinkage needed compensation. Effective expansion is therefore hygroscopic expansion minus post-gel shrinkage., (© International & American Associations for Dental Research 2016.)
- Published
- 2016
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32. Anthrax lethal toxin induces acute diastolic dysfunction in rats through disruption of the phospholamban signaling network.
- Author
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Golden HB, Watson LE, Nizamutdinov D, Feng H, Gerilechaogetu F, Lal H, Verma SK, Mukhopadhyay S, Foster DM, Dillmann WH, and Dostal DE
- Subjects
- Acute Disease, Animals, Calcium-Binding Proteins antagonists & inhibitors, Cells, Cultured, Male, Myocytes, Cardiac drug effects, Myocytes, Cardiac metabolism, Phosphorylation drug effects, Phosphorylation physiology, Rats, Rats, Sprague-Dawley, Signal Transduction drug effects, Antigens, Bacterial toxicity, Bacterial Toxins toxicity, Calcium-Binding Proteins metabolism, Heart Failure, Diastolic chemically induced, Heart Failure, Diastolic metabolism, Signal Transduction physiology
- Abstract
Background: Anthrax lethal toxin (LT), secreted by Bacillus anthracis, causes severe cardiac dysfunction by unknown mechanisms. LT specifically cleaves the docking domains of MAPKK (MEKs); thus, we hypothesized that LT directly impairs cardiac function through dysregulation of MAPK signaling mechanisms., Methods and Results: In a time-course study of LT toxicity, echocardiography revealed acute diastolic heart failure accompanied by pulmonary regurgitation and left atrial dilation in adult Sprague-Dawley rats at time points corresponding to dysregulated JNK, phospholamban (PLB) and protein phosphatase 2A (PP2A) myocardial signaling. Using isolated rat ventricular myocytes, we identified the MEK7-JNK1-PP2A-PLB signaling axis to be important for regulation of intracellular calcium (Ca(2+)(i)) handling, PP2A activation and targeting of PP2A-B56α to Ca(2+)(i) handling proteins, such as PLB. Through a combination of gain-of-function and loss-of-function studies, we demonstrated that over-expression of MEK7 protects against LT-induced PP2A activation and Ca(2+)(i) dysregulation through activation of JNK1. Moreover, targeted phosphorylation of PLB-Thr(17) by Akt improved sarcoplasmic reticulum Ca(2+)(i) release and reuptake during LT toxicity. Co-immunoprecipitation experiments further revealed the pivotal role of MEK7-JNK-Akt complex formation for phosphorylation of PLB-Thr(17) during acute LT toxicity., Conclusions: Our findings support a cardiogenic mechanism of LT-induced diastolic dysfunction, by which LT disrupts JNK1 signaling and results in Ca(2+)(i) dysregulation through diminished phosphorylation of PLB by Akt and increased dephosphorylation of PLB by PP2A. Integration of the MEK7-JNK1 signaling module with Akt represents an important stress-activated signalosome that may confer protection to sustain cardiac contractility and maintain normal levels of Ca(2+)(i) through PLB-T(17) phosphorylation., (© 2013.)
- Published
- 2013
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33. Echocardiographic effects of eplerenone and aldosterone in hypertensive rats.
- Author
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Watson LE, Jewell C, Song J, and Dostal DE
- Subjects
- Animals, Echocardiography, Eplerenone, Hypertension drug therapy, Male, Rats, Rats, Inbred SHR, Rats, Inbred WKY, Spironolactone therapeutic use, Aldosterone therapeutic use, Hypertension diagnostic imaging, Spironolactone analogs & derivatives
- Abstract
The effects of aldosterone receptor blockade on echocardiography in spontaneously hypertensive rats (SHR) are not fully characterized. In this study, multiple echocardiographic parameters were compared for 42 weeks between SHR versus Wistar-Kyoto rats (WKY) serving as normotensive controls. In addition, echocardiographic parameters were compared for 28 weeks between the SHR versus SHR treated with eplerenone 100 mg/kg/day or spironolactone 50 mg/kg/day. Compared to normotensive WKY rats, SHRs had significantly increased systolic blood pressure, increased cardiac mass, increased isovolumic relaxation time (IVRT), decreased E/A ratio, increased mitral closure opening time interval (MCO) and increased Tei index. Both eplerenone and spironolactone significantly decreased systolic blood pressure compared to the SHR controls. The spironolactone treatment group demonstrated significant increases in heart rate and cardiac output and a decrease in cardiac index compared to SHR controls. Any aldosterone blockade in SHR protected against the increased cardiac mass. Similar to clinical echocardiographic observations, hypertension in rats results in left ventricular hypertrophy (LVH) and diastolic dysfunction and aldosterone receptor blockade reduces LVH in SHR.
- Published
- 2013
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34. The genetic ghost of an invasion past: colonization and extinction revealed by historical hybridization in Senecio.
- Author
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Pelser PB, Abbott RJ, Comes HP, Milton JJ, Möller M, Looseley ME, Cron GV, Barcelona JF, Kennedy AH, Watson LE, Barone R, Hernández F, and Kadereit JW
- Subjects
- Africa, Southern, Amino Acid Sequence, Biological Evolution, Cloning, Molecular, DNA, Plant genetics, Genetic Variation, Molecular Sequence Data, Morocco, Phylogeny, Phylogeography, Recombination, Genetic, Sequence Alignment, Sequence Analysis, DNA, Spain, Extinction, Biological, Hybridization, Genetic, Introduced Species, Senecio classification, Senecio genetics
- Abstract
Hybridization is an important evolutionary factor in the diversification of many plant and animal species. Of particular interest is that historical hybridization resulting in the origin of new species or introgressants has occurred between species now geographically separated by great distances. Here, we report that Senecio massaicus, a tetraploid species native to Morocco and the Canary Islands, contains genetic material of two distinct, geographically separated lineages: a Mediterranean lineage and a mainly southern African lineage. A time-calibrated internal transcribed spacer phylogeny indicates that the hybridization event took place up to 6.18 Ma. Because the southern African lineage has never been recorded from Morocco or the Canary Islands, we hypothesize that it reached this area in the distant past, but never became permanently established. Interestingly, the southern African lineage includes S. inaequidens, a highly invasive species that has recently become widespread throughout Europe and was introduced at the end of the 19th century as a 'wool alien'. Our results suggest that this more recent invasion of Europe by S. inaequidens represents the second arrival of this lineage into the region., (© 2011 Blackwell Publishing Ltd.)
- Published
- 2012
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35. Evolution and variation of the nifD and hupL elements in the heterocystous cyanobacteria.
- Author
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Henson BJ, Hartman L, Watson LE, and Barnum SR
- Subjects
- Base Sequence, Cyanobacteria classification, Cyanobacteria metabolism, Fatty Acids metabolism, Molecular Sequence Data, Phylogeny, Recombination, Genetic, Bacterial Proteins genetics, Cyanobacteria genetics, Cyanobacteria growth & development, Evolution, Molecular, Genetic Variation
- Abstract
In heterocystous cyanobacteria, heterocyst differentiation is accompanied by developmentally regulated DNA rearrangements that occur within the nifD and hupL genes, referred to as the nifD and hupL elements. These elements are segments of DNA that are embedded within the coding region of each gene and range from 4 to 24 kb in length. The nifD and hupL elements are independently excised from the genome during the later stages of differentiation by the site-specific recombinases, XisA and XisC, respectively, which are encoded within the elements themselves. Here we examine the variation and evolution of the nifD and hupL elements by comparing full-length nifD and hupL element sequences and by phylogenetic analysis of xisA and xisC gene sequences. There is considerable variation in the size and composition of the nifD and hupL elements, however, conserved regions are also present within representatives of each element. The data suggest that the nifD and hupL elements have undergone a complex pattern of insertions, deletions, translocations and sequence divergence over the course of evolution, but that conserved regions remain.
- Published
- 2011
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36. Mycorrhizal specificity in the fully mycoheterotrophic Hexalectris Raf. (Orchidaceae: Epidendroideae).
- Author
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Kennedy AH, Taylor DL, and Watson LE
- Subjects
- Mycorrhizae classification, Phylogeny, Mycorrhizae genetics, Orchidaceae microbiology
- Abstract
Mycoheterotrophic species have abandoned an autotrophic lifestyle and obtain carbon exclusively from mycorrhizal fungi. Although these species have evolved independently in many plant families, such events have occurred most often in the Orchidaceae, resulting in the highest concentration of these species in the tracheophytes. Studies of mycoheterotrophic species' mycobionts have generally revealed extreme levels of mycorrhizal specialization, suggesting that this system is ideal for studying the evolution of mycorrhizal associations. However, these studies have often investigated single or few, often unrelated, species without consideration of their phylogenetic relationships. Herein, we present the first investigation of the mycorrhizal associates of all species of a well-characterized orchid genus comprised exclusively of mycoheterotrophic species. With the employment of molecular phylogenetic methods, we identify the fungal associates of each of nine Hexalectris species from 134 individuals and 42 populations. We report that Hexalectris warnockii associates exclusively with members of the Thelephoraceae, H. brevicaulis and H. grandiflora associate with members of the Russulaceae and Sebacinaceae subgroup A, while each member of the H. spicata species complex associates primarily with unique sets of Sebacinaceae subgroup A clades. These results are consistent with other studies of mycorrhizal specificity within mycoheterotrophic plants in that they suggest strong selection within divergent lineages for unique associations with narrow clades of mycorrhizal fungi. Our results also suggest that mycorrhizal associations are a rapidly evolving characteristic in the H. spicata complex., (© 2011 Blackwell Publishing Ltd.)
- Published
- 2011
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37. Norepinephrine induces systolic failure and inhibits antiapoptotic genes in a polymicrobial septic rat model.
- Author
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Chopra M, Das P, Golden H, Dostal DE, Watson LE, and Sharma AC
- Subjects
- Animals, Disease Models, Animal, Disease Progression, Echocardiography, Interleukin-10 genetics, Male, Polymerase Chain Reaction, Rats, Rats, Sprague-Dawley, Sepsis microbiology, Time Factors, Tumor Necrosis Factor-alpha genetics, Up-Regulation drug effects, Ventricular Dysfunction etiology, Apoptosis drug effects, Norepinephrine physiology, Sepsis complications, Vasoconstrictor Agents therapeutic use, Ventricular Dysfunction physiopathology
- Abstract
Aims: We examined the effect of norepinephrine (NE) infusion on left ventricular function and apoptotic genes during progression of polymicrobial sepsis., Methods: Male Sprague-Dawley rats (350-400 g) were made septic by intraperitoneal (i.p.) administration of 200mg/kg cecal inoculum. Sham animals received 5% dextrose water, i.p. Echocardiography was performed at baseline, 3 days and 7 days post-sepsis/sham. NE (0.6 μgkg(-1)h(-1)) was infused for 2h, before the end of day 3 of echocardiography. At the end of day 7, rats were euthanized and heart tissues harvested for isolation of total RNA. PCR was performed using RT(2) profiler™ PCR array PARN-012 (Rat apoptosis array; SuperArray, MD) using RT(2) Real-Time™ SYBR Green PCR master mix PA-012., Key Findings: NE-infusion resulted in a significant decrease in the left ventricular ejection fraction (EF) (62.56±2.07 from the baseline 71.11±3.23, p<0.05) and fractional shortening (FS) (39.90±2.64 from the sham group 54.41±2.19, p<0.05) at 7 days post-sepsis, respectively. Super Array data revealed that during sepsis, tumor necrosis factor (TNF-α) (2.85±0.07 fold, p<0.0001), anti-apoptotic molecules, Prok2 (16.07±0.48 fold, p<0.0001) and interleukin-10 (IL-10) (23.5±0.57 fold, p<0.0001) were up regulated at day 1. At 7-days post-sepsis, CD40l g (2.49±0.54 fold, p<0.08) and Birc1b (17.8±0.58 fold, p<0.0001) were up regulated compared to the sham, 1 and 3-days post-sepsis groups., Significance: The data suggest that upregulation of a series of pro-apoptotic molecules could be responsible for systolic and diastolic dysfunction during 3 and 7 days post sepsis., (Copyright © 2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
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38. Patterns and causes of incongruence between plastid and nuclear Senecioneae (Asteraceae) phylogenies.
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Pelser PB, Kennedy AH, Tepe EJ, Shidler JB, Nordenstam B, Kadereit JW, and Watson LE
- Abstract
One of the longstanding questions in phylogenetic systematics is how to address incongruence among phylogenies obtained from multiple markers and how to determine the causes. This study presents a detailed analysis of incongruent patterns between plastid and ITS/ETS phylogenies of Tribe Senecioneae (Asteraceae). This approach revealed widespread and strongly supported incongruence, which complicates conclusions about evolutionary relationships at all taxonomic levels. The patterns of incongruence that were resolved suggest that incomplete lineage sorting (ILS) and/or ancient hybridization are the most likely explanations. These phenomena are, however, extremely difficult to distinguish because they may result in similar phylogenetic patterns. We present a novel approach to evaluate whether ILS can be excluded as an explanation for incongruent patterns. This coalescence-based method uses molecular dating estimates of the duration of the putative ILS events to determine if invoking ILS as an explanation for incongruence would require unrealistically high effective population sizes. For four of the incongruent patterns identified within the Senecioneae, this approach indicates that ILS cannot be invoked to explain the observed incongruence. Alternatively, these patterns are more realistically explained by ancient hybridization events.
- Published
- 2010
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- View/download PDF
39. Enhanced external counterpulsation is a regenerative therapy.
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Jewell CW, Houck PD, Watson LE, Dostal DE, and Dehmer GJ
- Subjects
- Aged, Aged, 80 and over, Biomechanical Phenomena, Blood Flow Velocity, Female, Flow Cytometry, Humans, Male, Middle Aged, Pilot Projects, Regenerative Medicine methods, Angina Pectoris therapy, Cell Proliferation, Counterpulsation methods, Endothelial Cells cytology, Heart Failure therapy, Hematopoietic Stem Cells cytology
- Abstract
Enhanced external counterpulsation (EECP) is used for the treatment of severe angina and heart failure in patients who are not candidates for revascularization. The clinical benefits of EECP extend well beyond the time period of any hemodynamic effects, but the cause of this prolonged effect is not understood. The prolonged clinical benefits suggest EECP could be a regenerative therapy. This study was performed to determine whether EECP increased circulating hematopoietic progenitor cells (HPCs) or endothelial progenitor cells (EPCs) and thus be a possible regenerative therapy. The proposed mechanism of the increase in regenerative circulating stem cells is the enhanced shear forces induced on the endothelial boundary by the flow reversal produced by the sequential inflation of the pneumatic cuffs during EECP therapy.
- Published
- 2010
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40. Integrins and proximal signaling mechanisms in cardiovascular disease.
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Lal H, Verma SK, Foster DM, Golden HB, Reneau JC, Watson LE, Singh H, and Dostal DE
- Subjects
- Cardiovascular Diseases metabolism, Cardiovascular Diseases therapy, Cell Membrane metabolism, Humans, Integrins metabolism, Receptor Cross-Talk, Cardiovascular Diseases physiopathology, Integrins physiology, Signal Transduction
- Abstract
Integrins are heterodimeric cell-surface molecules, which act as the principle mediators of molecular dialog between a cell and its extracellular matrix environment. In addition to their structural functions, integrins mediate signaling from the extracellular space into the cell through integrin-associated signaling and adaptor molecules such as FAK (focal adhesion kinase), ILK (integrin-linked kinase), PINCH (particularly interesting new cysteine-histidine rich protein) and Nck2 (non-catalytic (region of) tyrosine kinase adaptor protein-2). Via these molecules, integrin signaling tightly and cooperatively interacts with receptor tyrosine kinases (RTKs) signaling to regulate survival, proliferation and cell shape as well as polarity, adhesion, migration and differentiation. In the heart and blood vessels, the function and regulation of these molecules can be partially disturbed and thus contribute to cardiovascular diseases such as cardiac hypertrophy and atherosclerosis. In this review, we discuss the primary mechanisms of action and signaling of integrins in the cardiac and vascular system in normal and pathological states, as well as therapeutic strategies for targeting these systems (1).
- Published
- 2009
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41. Anthrax toxin: pathologic effects on the cardiovascular system.
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Golden HB, Watson LE, Lal H, Verma SK, Foster DM, Kuo SR, Sharma A, Frankel A, and Dostal DE
- Subjects
- Anthrax physiopathology, Anthrax therapy, Antigens, Bacterial chemistry, Antigens, Bacterial metabolism, Bacterial Toxins chemistry, Bacterial Toxins metabolism, Humans, Antigens, Bacterial toxicity, Bacterial Toxins toxicity, Cardiovascular System drug effects
- Abstract
Anthrax is a disease caused by infection with spores from the bacteria Bacillus anthracis. After entering the body, the spores germinate into bacteria and secrete a toxin that causes local edema and, in systemic infections, cardiovascular collapse and death. The toxin is a tripartite polypeptide, consisting of protective antigen (PA), lethal factor (LF) and edema factor (EF), which have key roles in the bacterial pathogenesis and disease progression. PA facilitates transfer of LF and EF to the cytosol. Lethal toxin is a zinc metalloproteinase, which has the capacity to inactivate mitogen-activated protein (MAP) kinase kinase (MEK) and stimulates the release of sepsis-related cytokines tumor necrosis factor-alpha and interleukin-1beta. Edema factor is a calmodulin (CaM)-dependent adenylate cyclase, which increases levels of cyclic AMP, causing impaired neutrophil function and disruption of water balance that ultimately results in massive tissue edema. Together, the toxins effectively inhibit host innate and adaptive immune responses, allowing the bacteria to grow unrestrained and overwhelming any resistance. Clinically, inhalational anthrax presents in a biphasic pattern with initial nonspecific "flu-like" symptoms nausea and vomiting 1 to 4 days after exposure, followed by severe illness with dyspnea, high fever and circulatory shock. The latter symptoms represent a terminal stage and treatment is often ineffective when started at that time. Key indicators of early anthrax cardiovascular-related pathogenesis include mediastinal widening in association with pleural effusion and edema. In this review, we describe the current understanding of anthrax toxins on cellular function in the context of cardiovascular function and discuss potential therapeutic strategies.
- Published
- 2009
- Full Text
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42. Guidewire pacing safely and effectively treats bradyarrhythmias induced by rheolytic thrombectomy and precludes the need for transvenous pacing: the Scott & White experience.
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Mixon TA, Dehmer GJ, Santos RA, Gantt DS, Lawrence ME, and Watson LE
- Subjects
- Adult, Aged, Aged, 80 and over, Bradycardia etiology, Female, Humans, Male, Middle Aged, Retrospective Studies, Risk Factors, Thrombectomy methods, Time Factors, Bradycardia therapy, Cardiac Catheterization adverse effects, Coronary Thrombosis therapy, Coronary Vessels pathology, Thrombectomy adverse effects
- Abstract
Rheolytic thrombectomy (RT) is useful in certain percutaneous coronary interventions but may be associated with transient bradyarrhythmias. Clinicians have devised numerous strategies to deal with these arrhythmias apart from transvenous right ventricular pacing, some of which are described in other parts of this supplement. We report the Scott & White experience utilizing guidewire pacing to quickly and safely pace the heart in the event of bradyarrhythmia. We found this method to be safe and reliable (96.2% successful) during RT and now use this technique almost exclusively in the cardiac catheterization lab to deal with transient bradyarrhythmias during RT or due to any other cause.We also report an increased incidence of bradyarrhythmia occurring during RT when it is performed in the right coronary artery, with a trend toward an increased incidence during the clinical presentation of ST-elevation myocardial infarction.
- Published
- 2008
43. Excision of the nifD element in the heterocystous cyanobacteria.
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Henson BJ, Pennington LE, Watson LE, and Barnum SR
- Subjects
- Bacterial Proteins chemistry, Bacterial Proteins genetics, Bacterial Proteins metabolism, Base Sequence, DNA, Bacterial chemistry, DNA, Bacterial genetics, Escherichia coli genetics, Nitrogenase genetics, Nostoc chemistry, Nostoc metabolism, Plasmids chemistry, Plasmids genetics, Recombinases genetics, Nitrogenase chemistry, Nostoc genetics, Recombinases metabolism, Recombination, Genetic
- Abstract
Heterocyst differentiation in cyanobacteria is accompanied by developmentally regulated DNA rearrangements that occur within the nifD, fdxN, and hupL genes. These genetic elements are excised from the genome by site-specific recombination during the latter stages of differentiation. The nifD element is excised by the recombinase, XisA, located within the element. Our objective was to examine the XisA-mediated excision of the nifD element. To accomplish this, we observed the ability of XisA to excise substrate plasmids that contained the flanking regions of the nifD element in an E. coli host. Using PCR directed mutagenesis, nucleotides in the nifD element flanking regions in substrate plasmids were altered and the effect on recombination was determined. Results indicate that only certain nucleotides within and surrounding the direct repeats are involved in excision. In some nucleotide positions, the presence of a purine versus a pyrimidine greatly affected recombination. Our results also indicated that the site of excision and branch migration occurs in a 6 bp region within the direct repeats.
- Published
- 2008
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44. Anthrax toxins induce shock in rats by depressed cardiac ventricular function.
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Watson LE, Kuo SR, Katki K, Dang T, Park SK, Dostal DE, Tang WJ, Leppla SH, and Frankel AE
- Subjects
- Animals, Antigens, Bacterial blood, Bacterial Toxins blood, Heart physiopathology, Heart Ventricles physiopathology, Rats, Rats, Sprague-Dawley, Viper Venoms blood, Antigens, Bacterial toxicity, Bacterial Toxins toxicity, Heart drug effects, Heart Ventricles drug effects, Shock chemically induced, Viper Venoms toxicity
- Abstract
Anthrax infections are frequently associated with severe and often irreversible hypotensive shock. The isolated toxic proteins of Bacillus anthracis produce a non-cytokine-mediated hypotension in rats by unknown mechanisms. These observations suggest the anthrax toxins have direct cardiovascular effects. Here, we characterize these effects. As a first step, we administered systemically anthrax lethal toxin (LeTx) and edema toxin (EdTx) to cohorts of three to twelve rats at different doses and determined the time of onset, degree of hypotension and mortality. We measured serum concentrations of the protective antigen (PA) toxin component at various time points after infusion. Peak serum levels of PA were in the microg/mL range with half-lives of 10-20 minutes. With doses that produced hypotension with delayed lethality, we then gave bolus intravenous infusions of toxins to groups of four to six instrumented rats and continuously monitored blood pressure by telemetry. Finally, the same doses used in the telemetry experiments were given to additional groups of four rats, and echocardiography was performed pretreatment and one, two, three and twenty-four hours post-treatment. LeTx and EdTx each produced hypotension. We observed a doubling of the velocity of propagation and 20% increases in left ventricular diastolic and systolic areas in LeTx-treated rats, but not in EdTx-treated rats. EdTx-but not LeTx-treated rats showed a significant increase in heart rate. These results indicate that LeTx reduced left ventricular systolic function and EdTx reduced preload. Uptake of toxins occurs readily into tissues with biological effects occurring within minutes to hours of serum toxin concentrations in the microg/mL range. LeTx and EdTx yield an irreversible shock with subsequent death. These findings should provide a basis for the rational design of drug interventions to reduce the dismal prognosis of systemic anthrax infections.
- Published
- 2007
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45. Lethal and edema toxins of anthrax induce distinct hemodynamic dysfunction.
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Watson LE, Mock J, Lal H, Lu G, Bourdeau RW, Tang WJ, Leppla SH, Dostal DE, and Frankel AE
- Subjects
- Animals, Electrocardiography, Heart physiology, Humans, Rats, Rats, Sprague-Dawley, Adenylyl Cyclases pharmacology, Antigens, Bacterial pharmacology, Bacterial Toxins pharmacology, Heart drug effects
- Abstract
Fatalities due to anthrax are associated with severe hypotension suggesting that the toxins generated from Bacillus anthracis, lethal toxin (LeTx) and edema toxin (EdTx), have cardiovascular effects. Here, we demonstrate the effects of these toxins and characterize their effects by echocardiography. LeTx leads to a significant reduction in ejection fraction, decreased velocity of propagation (diastolic dysfunction), decreased velocity of circumferential fiber shortening (decreased contractility), and increased LV systolic area (pathophysiology). EdTx leads to a significant reduction in left ventricular volumes and cardiac output (reduced stroke volume) but does not cause significant change in ejection fraction or contractility. These results indicate that LeTx reduces left ventricular systolic function and EdTx reduces preload but does not have direct myocardial effects. Together, these findings suggest that LeTx and EdTx exert distinct hemodynamic dysfunction associated with anthrax infection.
- Published
- 2007
- Full Text
- View/download PDF
46. Integrins: novel therapeutic targets for cardiovascular diseases.
- Author
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Lal H, Guleria RS, Foster DM, Lu G, Watson LE, Sanghi S, Smith M, and Dostal DE
- Subjects
- Cardiovascular Agents chemistry, Cardiovascular Physiological Phenomena, Endothelium, Vascular drug effects, Endothelium, Vascular growth & development, Extracellular Matrix drug effects, Humans, Randomized Controlled Trials as Topic, Signal Transduction drug effects, Signal Transduction physiology, Cardiovascular Agents pharmacology, Cardiovascular Diseases drug therapy, Endothelium, Vascular metabolism, Extracellular Matrix metabolism, Integrins antagonists & inhibitors, Integrins drug effects, Integrins metabolism
- Abstract
Integrins are the principle mediators of molecular dialog between a cell and its extracellular matrix environment. The unique combinations of integrin subunits determine which extracellular matrix molecules are recognized by a cell. Recent studies have demonstrated that remodeling in heart and vasculature is linked to alterations in extracellular matrix and integrin expression. The roles of integrins in controlling cellular behavior have made these molecules highly attractive drug targets. New insights into mechanisms whereby the extracellular matrix takes part in the control of smooth muscle cell proliferation and cardiac growth suggest a number of putative targets for future therapies that can be applied to increase plaque stability, prevent the clinical consequences of atherosclerosis and improve outcomes after interventional procedures such as cardiac transplantation. Therapeutic candidates include antibodies, cyclic peptides, peptidomimetics and small molecules. The integrin inhibitors Integrilin and ReoPro have been approved as blood thinners in cardiovascular disease, and newer agents are undergoing testing. Although integrin function is important in the cardiovascular system, there are wide gaps in knowledge. In this review, we discuss the primary mechanisms of action and signaling of integrins in the cardiac and vascular system in normal and pathological states, as well as therapeutic strategies for targeting these molecules in the cardiovascular system.
- Published
- 2007
- Full Text
- View/download PDF
47. Stem diversity, cauline domatia, and the evolution of ant-plant associations in Piper sect. Macrostachys (Piperaceae).
- Author
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Tepe EJ, Vincent MA, and Watson LE
- Abstract
Plants possess a variety of structures that harbor ant nests, and the morphology of these domatia determines the nature of ant-plant mutualisms in a given plant species. In this study, we report on the differences in anatomy between myrmecophytes of Piper, which are regularly excavated by an obligate ant mutualist (Pheidole bicornis) and nonmyrmecophytes of Piper, which consistently have solid stems. Stems of excavated plant species lacked outward evidence of modification; however, striking anatomical differences were apparent between hollow-stemmed species before excavation and the remainder of the solid-stemmed species studied. Prior to excavation by ants, stems of myrmecophytes were characterized by strongly heterogeneous piths in which a large, central area had relatively large cells lacking intracellular crystals with a periphery of smaller cells containing numerous crystals. The domatium excavated by the ants was restricted to the large-celled region. This is the first report of the absence of crystals in ant-excavated portions of stems of myrmecophytes. Cauline domatia became lined with 3-8 cell layers of suberized wound tissue, which may have an impact on nutrient absorption by Piper myrmecophytes.
- Published
- 2007
- Full Text
- View/download PDF
48. Cyclooxygenase-2 inhibitors: a painful lesson.
- Author
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Sanghi S, MacLaughlin EJ, Jewell CW, Chaffer S, Naus PJ, Watson LE, and Dostal DE
- Subjects
- Animals, Anti-Inflammatory Agents, Non-Steroidal therapeutic use, Clinical Trials as Topic, Consumer Product Safety, Cyclooxygenase 2 Inhibitors therapeutic use, Humans, Anti-Inflammatory Agents, Non-Steroidal adverse effects, Cardiovascular Diseases chemically induced, Cyclooxygenase 2 Inhibitors adverse effects
- Abstract
Non-steroidal anti-inflammatory drugs (NSAIDs) represent a clinically important class of agents. NSAIDs are commonly used in treatment of conditions such as headache, fever, inflammation and joint pain. Complications often arise from chronic use of NSAIDs. Gastrointestinal (GI) toxicity in the form of gastritis, peptic erosions and ulcerations and GI bleeds limit usage of NSAIDs. These toxicities are thought to be due to cyclooxygenase (COX)-1 blockade. COX-1 generates cytoprotective prostanoids such as prostaglandin (PG) E2 and prostacyclin (PGI2). COX-2 inhibitors, commonly referred to as coxibs, were developed to inhibit inflammatory prostanoids without interfering with production of COX-1 prostanoids. Concerns over cardiovascular safety, however, have evolved based on the concept of inhibition of COX-2-derived endothelial prostanoids without inhibition of platelet thromboxane A2, leading to increased cardiovascular risk. The Celecoxib Long-Term Arthritis Safety Study (CLASS) trial did not show a significant increase in cardiovascular risk for celecoxib (Celebrex), but results of the Vioxx Gastrointestinal Outcomes Research (VIGOR) study showed an increased cardiovascular risk with long-term daily usage of rofecoxib in patients with rheumatoid arthritis. The Adenomatous Poly Prevention on Vioxx (APPROVe) trial further evaluated cardiovascular effects of rofecoxib and recently led to removal of this drug from the marketplace. Coxibs affect renal function via blockade of normal COX-2 functions. COX-2 expression increases in high renin states and in response to a high-sodium diet or water deprivation. PGI2 and PGE2 are the most important renal prostanoids. PGI2 inhibition results in hyperkalemia. PGE2 inhibition results in sodium retention, which leads to hypertension, peripheral edema and potentially exacerbation of heart failure. This review article discusses beneficial and deleterious effects associated with prostanoids produced by COX-1 and COX-2 in various organs and how blockade of these products translates into clinical medicine.
- Published
- 2006
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49. Understanding diastolic heart failure with preserved ejection fraction: choosing the right model.
- Author
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Dostal DE and Watson LE
- Subjects
- Animals, Diastole, Humans, Stroke Volume, Disease Models, Animal, Heart Failure physiopathology
- Published
- 2006
- Full Text
- View/download PDF
50. Aldosterone receptor antagonists and cardiovascular disease: do we need a change of the guard?
- Author
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Jewell CW, Watson LE, Mock J, and Dostal DE
- Subjects
- Aldosterone physiology, Cardiovascular Diseases physiopathology, Female, Humans, Male, Spironolactone pharmacology, Cardiovascular Diseases drug therapy, Mineralocorticoid Receptor Antagonists
- Abstract
Aldosterone is a mineralocorticoid primarily produced in the zona glomerulosa of the adrenal gland. For many years, aldosterone (Aldo) was thought to have its sole site of action in the kidney, where it regulated sodium excretion and potassium reabsorption. It is now known that Aldo is produced in cardiovascular tissues, and has been implicated in the development of ventricular hypertrophy and cardiac fibrosis. The precise mechanisms whereby Aldo acts in cardiac tissues are diverse. It was assumed that Aldo production could be limited by angiotensin-converting enzyme (ACE) inhibition, but serial measurements during therapy reveal only a transient decrease in Aldo levels. Moreover, the effects of Aldo on cardiac tissues occur even when angiotensin II (Ang II) has been suppressed or eliminated. Multiple investigators have examined effects of Aldo receptor blockade in human subjects and various animal models using the two Aldo receptor antagonists (ARAs), spironolactone and eplerenone. Major clinical trials involving spironolactone (RALES) and eplerenone (EPHESUS) ARAs have shown significant benefits in the treatment of congestive heart failure (CHF). In RALES, patients with New York Heart Association (NYHA) Class III or IV systolic heart failure treated with spironolactone had a 30% relative risk decrease in mortality. Although spironolactone is an effective competitive inhibitor of the mineralocorticoid receptor (MR), progestational and antiandrogenic side effects limit its use in some patients. Eplerenone, a more selective ARA, lacks these undesirable side effects. Although eplerenone is 20-fold less potent at the MR, it demonstrates efficacy similar to spironolactone, possibly due to decreased protein binding. Eplerenone has fewer side effects than spironolactone, which has been attributed to the low cross-reactivity with androgen and progesterone receptors. In EPHESUS, patients with left ventricular systolic dysfunction [Ejection Fraction (EF) <40%] and CHF following an acute myocardial infarction (AMI), were treated with eplerenone, resulting in a 17% reduction in cardiovascular mortality. However, these studies were limited in that diastolic function was not evaluated, although approximately 1/2 of CHF is due to diastolic dysfunction alone. To date, neither ARA has been studied for the treatment of diastolic dysfunction in a major clinical trial. However, numerous animal studies employing ARAs have shown a decrease in cardiac hypertrophy and fibrosis, indicating the potential benefits of these agents in the treatment of diastolic heart failure. In this review, we discuss possible underlying mechanisms responsible for Aldo effects on cardiovascular function and compare the beneficial effects of spironolactone and eplerenone in the treatment of heart disease.
- Published
- 2006
- Full Text
- View/download PDF
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