39 results on '"Chacko S"'
Search Results
2. Concept development and CAE for EV battery thermal management
- Author
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Chacko, S., primary and Charmer, S., additional
- Published
- 2011
- Full Text
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3. Proterodiplostomid no longer: Molecular phylogeny reveals the true position of Proalarioides (Digenea: Diplostomoidea).
- Author
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Achatz TJ, Chacko S, Prasadan PK, and Tkach VV
- Abstract
Proalarioides Yamaguti, 1933 (Digenea Carus, 1863: Diplostomoidea Poirier, 1886) is a small genus of proterodiplostomids parasitic in the intestines of snakes in Asia. Only two species are considered valid: Proalarioides serpentis Yamaguti, 1933 and Proalarioides tropidonotis Vidyarthi, 1937. Unlike other proterodiplostomids, Proalarioides spp. possess pseudosuckers and lack the paraprostate, otherwise extremely characteristic of the Proterodiplostomidae Dubois, 1936. In the present study, we describe the morphology of progenetic metacercariae of a Proalarioides sp. from bicolored frog, Clinotarsus curtipes (Jerdon), collected in India and provide the first DNA sequences from any member of the genus. These specimens differ from previously described metacercariae and adults of P. serpentis and P. tropidonotis in several ways, including body and organ sizes, sucker ratios, and distribution of vitellarium. The newly generated partial large ribosomal subunit (28S) rRNA gene sequence was used to test the phylogenetic position of the genus among other major lineages of diplostomoideans. Our 28S phylogeny clearly demonstrated Proalarioides sp. to be well-separated from other members of the Proterodiplostomidae. Based on morphological and molecular evidence, we transfer Proalarioides out of the Proterodiplostomidae into the Diplostomidae Poirier, 1886., Competing Interests: Declaration of competing interest All authors disclose that there was no conflict of interest of any type from the beginning of the work to the submission of manuscript., (Copyright © 2024 Elsevier B.V. All rights reserved.)
- Published
- 2024
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4. Hemiazygos vein dilation as a radiological finding and multifactorial cause of dysphagia.
- Author
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Khatri S, Chamay S, Chacko S, and Sharma S
- Abstract
Dysphagia is a common issue observed among the elderly, which can arise from various etiologies such as motility disorders and chronic neurologic conditions. Radiologists play a crucial role in diagnosing the cause of dysphagia, as they can identify anatomical abnormalities that may lead to the condition. One such anomaly is the hemiazygos vein, which is the left side equivalent of the azygos vein and can cause dysphagia if it crosses over the esophagus. To our knowledge, there are only 2 other recorded cases of azygos aneurysm/dilation causing esophageal dysphagia. In this context, we present a case report of a 73-year-old female with a 1-month history of weight loss and dysphagia due to a prominent hemiazygos vein. The case highlights the importance of thorough radiological evaluation in identifying the underlying cause of dysphagia and ensuring timely and appropriate treatment., (Published by Elsevier Inc. on behalf of University of Washington.)
- Published
- 2023
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5. Long-term Outcomes in Treated Lyme Carditis.
- Author
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Wang CN, Yeung C, Enriquez A, Chacko S, Hanson S, Redfearn D, Simpson C, Abdollah H, and Baranchuk A
- Subjects
- Exercise Test, Humans, Male, Lyme Disease, Myocarditis
- Abstract
Lyme disease is the most reported tick-borne illness in North America. Lyme carditis (LC) is an early-disseminated manifestation of Lyme disease, most commonly presenting as symptomatic high-degree atrioventricular block (AVB) which resolves with appropriate antibiotic therapy. However, long-term outcomes of treated LC have not previously been described. We present a series of 7 patients (median 28 years, 6 male) with serologically confirmed LC treated with a standard protocol developed at our center including antibiotics and pre-discharge stress test to assess AV node stability. At a mean follow-up of 20.8 months, all patients were asymptomatic, had resumed normal activities, and were free of conduction abnormalities. None required permanent pacing. Our study supports avoidance of permanent pacing for LC if conduction is stable at discharge., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2022
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6. Cutaneous Toxicities in Breast Cancer Patients Receiving Chemotherapy and Targeted Agents--An Observational Clinical Study.
- Author
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Anoop TM, Joseph P R, Pn M, Kp P, Gopan G, and Chacko S
- Subjects
- Antineoplastic Agents administration & dosage, Cohort Studies, Female, Humans, Incidence, India, Middle Aged, Skin Diseases therapy, Antineoplastic Agents adverse effects, Breast Neoplasms drug therapy, Skin Diseases chemically induced, Skin Diseases epidemiology
- Abstract
Background: Systemic chemotherapy and targeted agents are associated with various cutaneous toxicities. Even though cutaneous toxicities are manageable, it often results in treatment discontinuation and worsens the patients' quality of life., Aim: The study aimed to determine the spectrum of cutaneous toxicities in patients receiving systemic chemotherapy and targeted agents for breast cancer patients., Patients and Methods: A total of 250 out of 720 patients with breast cancer who developed various cutaneous toxicities to chemotherapeutic or targeted agents were included in the study., Results: Among 250 patients, 57 patients were on neoadjuvant chemotherapy, 89 patients were on adjuvant chemotherapy, 68 were on palliative chemotherapy for metastatic breast cancer and 36 were on targeted treatment for metastatic breast cancer. The most frequently affected site was hair (96%), followed by skin (92%), nail (34%), and mucosa (26%). The most common dermatological toxicity noticed in our study involved the hair in the form of chemotherapy induced alopecia (anagen effluvium) in 93.6%, followed by skin toxicity with generalized xerosis in 92% and, nail toxicity in 34%, and mucosal toxicity in 26%. The most common chemotherapeutic agent which caused frequent cutaneous toxicities in our patients was docetaxel followed by paclitaxel, capecitabine, doxorubicin, epirubicine, cyclophosphamide, 5-flurouracil and targeted agents like lapatinib, everolimus, and tamoxifen., Conclusion: Cutaneous toxicities are common following systemic chemotherapy and targeted agents. Early recognition of cutaneous side effects of these agents and prompt early interventions can reduce the significant morbidity, cosmetic disfigurement, unnecessary treatment interruptions, and psychological distress in women treated for breast cancers., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2021
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7. Close-coupled pacing to identify the "functional" substrate of ventricular tachycardia: Long-term outcomes of the paced electrogram feature analysis technique.
- Author
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Crinion D, Neira V, Al Hamad N, de Leon A, Bakker D, Korogyi A, Abdollah H, Glover B, Simpson C, Baranchuk A, Chacko S, Enriquez A, and Redfearn D
- Subjects
- Aged, Feasibility Studies, Female, Follow-Up Studies, Humans, Male, Prospective Studies, Tachycardia, Ventricular therapy, Time Factors, Cardiac Pacing, Artificial methods, Electrophysiologic Techniques, Cardiac methods, Heart Rate physiology, Heart Ventricles physiopathology, Tachycardia, Ventricular physiopathology
- Abstract
Background: The conduction delay and block that compose the critical isthmus of macroreentrant ventricular tachycardia (VT) is partly "functional" in that they only occur at faster cycle lengths. Close-coupled pacing stresses the myocardium's conduction capacity and may reveal late potentials (LPs) and fractionation. Interest has emerged in targeting this functional substrate., Objective: The purpose of this study was to assess the feasibility and efficacy of a functional substrate VT ablation strategy., Methods: Patients with scar-related VT undergoing their first ablation were recruited. A closely coupled extrastimulus (ventricular effective refractory period + 30 ms) was delivered at the right ventricular apex while mapping with a high-density catheter. Sites of functional impaired conduction exhibited increased electrogram duration due to LPs/fractionation. The time to last deflection was annotated on an electroanatomic map, readily identifying ablation targets., Results: A total of 40 patients were recruited (34 [85%] ischemic). Median procedure duration was 330 minutes (interquartile range [IQR] 300-369), and ablation time was 49.4 minutes (IQR 33.8-48.3). Median functional substrate area was 41.9 cm
2 (IQR 22.1-73.9). It was similarly distributed across bipolar voltage zones. Noninducibility was achieved in 34 of 40 patients (85%). Median follow-up was 711 days (IQR 255.5-972.8), during which 35 of 39 patients (89.7%) did not have VT recurrence, and 3 of 39 (7.5%) died. Antiarrhythmic drugs were continued in 53.8% (21/39)., Conclusion: Functional substrate ablation resulted in high rates of noninducibility and freedom from VT. Mapping times were increased considerably. Our findings add to the encouraging trend reported by related techniques. Randomized multicenter trials are warranted to assess this next phase of VT ablation., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)- Published
- 2021
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8. Branched-Chain Amino Acid Oxidation Is Elevated in Adults with Morbid Obesity and Decreases Significantly after Sleeve Gastrectomy.
- Author
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Tan HC, Hsu JW, Kovalik JP, Eng A, Chan WH, Khoo CM, Tai ES, Chacko S, and Jahoor F
- Subjects
- Adult, Carbon Isotopes, Female, Humans, Isotope Labeling, Keto Acids metabolism, Male, Oxidation-Reduction, Amino Acids, Branched-Chain metabolism, Gastrectomy methods, Obesity, Morbid metabolism
- Abstract
Background: Plasma concentrations of branched-chain amino acids (BCAAs) are elevated in obese individuals with insulin resistance (IR) and decrease after bariatric surgery. However, the metabolic mechanisms are unclear., Objectives: Our objectives are to compare leucine kinetics between morbidly obese and healthy-weight individuals cross-sectionally, and to prospectively evaluate changes in the morbidly obese after sleeve gastrectomy. We hypothesized that leucine oxidation is slower in obese individuals and increases after surgery., Methods: Ten morbidly obese [BMI (in kg/m2) ≥32.5, age 21-50 y] and 10 healthy-weight participants (BMI <25), matched for age (median ∼30 y) but not gender, were infused with [U-13C6] leucine and [2H5] glycerol to quantify leucine and glycerol kinetics. Morbidly obese participants were studied again 6 mo postsurgery. Primary outcomes were kinetic parameters related to BCAA metabolism. Data were analyzed by nonparametric methods and presented as median (IQR)., Results: Participants with obesity had IR with an HOMA-IR (4.89; 4.36-8.76) greater than that of healthy-weight participants (1.32; 0.99-1.49; P < 0.001) and had significantly faster leucine flux [218; 196-259 compared with 145; 138-149 μmol · kg fat-free mass (FFM)-1 · h-1], oxidation (24.0; 17.9-29.8 compared with 16.1; 14.3-18.5 μmol · kg FFM-1 · h-1), and nonoxidative disposal (204; 190-247 compared with 138; 129-140 μmol · kg FFM-1 · h-1) (P < 0.017 for all). After surgery, the morbidly obese had a marked improvement in IR (3.54; 3.06-6.08; P = 0.008) and significant reductions in BCAA concentrations (113; 95-157 μmol/L) and leucine oxidation (9.37; 6.85-15.2 μmol · kg FFM-1 · h-1) (P = 0.017 for both). Further, leucine flux in this group correlated significantly with IR (r = 0.78, P < 0.001)., Conclusions: BCAA oxidation is not impaired but elevated in individuals with morbid obesity. Plasma BCAA concentrations are lowered after surgery owing to slower breakdown of body proteins as insulin's ability to suppress proteolysis is restored. These findings suggest that IR is the underlying cause and not the consequence of elevated BCAAs in obesity., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society for Nutrition.)
- Published
- 2020
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9. Parenteral lipids shape gut bile acid pools and microbiota profiles in the prevention of cholestasis in preterm pigs.
- Author
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Call L, Molina T, Stoll B, Guthrie G, Chacko S, Plat J, Robinson J, Lin S, Vonderohe C, Mohammad M, Kunichoff D, Cruz S, Lau P, Premkumar M, Nielsen J, Fang Z, Olutoye O, Thymann T, Britton R, Sangild P, and Burrin D
- Subjects
- Animals, Cholestasis complications, Parenteral Nutrition, Swine, Bile Acids and Salts metabolism, Cholestasis metabolism, Cholestasis microbiology, Lipid Metabolism, Microbiota, Premature Birth metabolism, Premature Birth microbiology
- Abstract
Multi-component lipid emulsions, rather than soy-oil emulsions, prevent cholestasis by an unknown mechanism. Here, we quantified liver function, bile acid pools, and gut microbial and metabolite profiles in premature parenterally fed pigs given a soy-oil lipid emulsion, Intralipid (IL), a multi component lipid emulsion, SMOFlipid (SMOF), a novel emulsion with a modified fatty-acid composition [experimental emulsion (EXP)], or a control enteral diet (ENT) for 22 days. We assayed serum cholestasis markers, measured total bile acid levels in plasma, liver, and gut contents, and analyzed colonic bacterial 16S rRNA gene sequences and metabolomic profiles. Serum cholestasis markers (i.e., bilirubin, bile acids, and γ-glutamyl transferase) were highest in IL-fed pigs and normalized in those given SMOF, EXP, or ENT. Gut bile acid pools were lowest in the IL treatment and were increased in the SMOF and EXP treatments and comparable to ENT. Multiple bile acids, especially their conjugated forms, were higher in the colon contents of SMOF and EXP than in IL pigs. The colonic microbial communities of SMOF and EXP pigs had lower relative abundance of several gram-positive anaerobes, including Clostridrium XIVa, and higher abundance of Enterobacteriaceae than those of IL and ENT pigs. Differences in lipid and microbial-derived compounds were also observed in colon metabolite profiles. These results indicate that multi-component lipid emulsions prevent cholestasis and restore enterohepatic bile flow in association with gut microbial and metabolomic changes. We conclude that sustained bile flow induced by multi-component lipid emulsions likely exerts a dominant effect in reducing bile acid-sensitive gram-positive bacteria.
- Published
- 2020
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10. NF-κB and GATA-Binding Factor 6 Repress Transcription of Caveolins in Bladder Smooth Muscle Hypertrophy.
- Author
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Thangavel C, Gomes CM, Zderic SA, Javed E, Addya S, Singh J, Das S, Birbe R, Den RB, Rattan S, Deshpande DA, Penn RB, Chacko S, and Boopathi E
- Subjects
- Aged, Animals, Biomarkers analysis, Caveolins genetics, Caveolins metabolism, GATA6 Transcription Factor genetics, Gene Expression Profiling, Gene Expression Regulation, Humans, Hypertrophy etiology, Hypertrophy metabolism, Male, Mice, Mice, Inbred C57BL, Middle Aged, Muscle Contraction, Muscle, Smooth metabolism, NF-kappa B genetics, Prostatic Hyperplasia metabolism, Prostatic Hyperplasia pathology, Urinary Bladder Neck Obstruction surgery, Caveolins antagonists & inhibitors, GATA6 Transcription Factor metabolism, Hypertrophy pathology, Muscle, Smooth pathology, NF-kappa B metabolism, Transcription, Genetic, Urinary Bladder Neck Obstruction complications
- Abstract
Caveolins (CAVs) are structural proteins of caveolae that function as signaling platforms to regulate smooth muscle contraction. Loss of CAV protein expression is associated with impaired contraction in obstruction-induced bladder smooth muscle (BSM) hypertrophy. In this study, microarray analysis of bladder RNA revealed down-regulation of CAV1, CAV2, and CAV3 gene transcription in BSM from models of obstructive bladder disease in mice and humans. We identified and characterized regulatory regions responsible for CAV1, CAV2, and CAV3 gene expression in mice with obstruction-induced BSM hypertrophy, and in men with benign prostatic hyperplasia. DNA affinity chromatography and chromatin immunoprecipitation assays revealed a greater increase in binding of GATA-binding factor 6 (GATA-6) and NF-κB to their cognate binding motifs on CAV1, CAV2, and CAV3 promoters in obstructed BSM relative to that observed in control BSM. Knockout of NF-κB subunits, shRNA-mediated knockdown of GATA-6, or pharmacologic inhibition of GATA-6 and NF-κB in BSM increased CAV1, CAV2, and CAV3 transcription and promoter activity. Conversely, overexpression of GATA-6 decreased CAV2 and CAV3 transcription and promoter activity. Collectively, these data provide new insight into the mechanisms by which CAV gene expression is repressed in hypertrophied BSM in obstructive bladder disease., (Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2019
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11. Mapping unmet supportive care needs, quality-of-life perceptions and current symptoms in cancer survivors across the Asia-Pacific region: results from the International STEP Study.
- Author
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Molassiotis A, Yates P, Li Q, So WKW, Pongthavornkamol K, Pittayapan P, Komatsu H, Thandar M, Yi M, Titus Chacko S, Lopez V, Butcon J, Wyld D, and Chan RJ
- Published
- 2019
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12. Alterations in branched-chain amino acid kinetics in nonobese but insulin-resistant Asian men.
- Author
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Tan HC, Hsu JW, Khoo CM, Tai ES, Yu S, Chacko S, Lai OF, and Jahoor F
- Subjects
- Adult, Asian People, Blood Glucose analysis, Carbon Isotopes, Glucose Tolerance Test, Humans, Insulin blood, Leucine pharmacokinetics, Male, Oxidation-Reduction, Palmitic Acid pharmacokinetics, Amino Acids, Branched-Chain blood, Amino Acids, Branched-Chain pharmacokinetics, Fatty Acids, Nonesterified blood, Fatty Acids, Nonesterified pharmacokinetics, Insulin Resistance physiology
- Abstract
Background: Branched-chain amino acids (BCAAs) are elevated in the insulin-resistant (IR) state. The reasons for this increase remain unclear, but it may be related to abnormalities in BCAA metabolism and free fatty acid (FFA) metabolism., Objective: In this study, we quantified BCAA and FFA kinetics of IR and insulin-sensitive (IS) nonobese Asian men with the use of stable-isotope tracers. We hypothesized that in addition to greater substrate flux, the BCAA oxidative pathway is also impaired to account for the higher plasma BCAA concentration in the IR state., Design: We recruited 12 IR and 14 IS nonobese and healthy Asian men. Oral-glucose-tolerance tests (OGTTs) were performed to quantify insulin sensitivity, and subjects underwent 2 stable-isotope infusion studies. [U-13C6]Leucine was infused to measure leucine flux and oxidation as indexes of BCAA metabolism, whereas [U-13C16]palmitate was infused to measure palmitate flux and oxidation to represent FFA metabolism, The 2H2O dilution method was used to estimate body composition., Results: IR subjects had greater adiposity and significantly higher fasting and post-OGTT glucose and insulin concentrations compared with the IS group. However, none of the subjects were diabetic. Despite similar dietary protein intake, IR subjects had a significantly higher plasma BCAA concentration and greater leucine flux. Leucine oxidation was also greater in the IR group, but the relation between leucine oxidation and flux was significantly weaker in the IR group than in the IS group (r = 0.530 compared with 0.695, P < 0.0388 for differences between slope). FFA oxidation was, however, unaffected despite higher FFA flux in the IR group., Conclusion: The higher plasma BCAA concentration in healthy nonobese individuals with IR is associated with a weaker relation between BCAA oxidation and BCAA flux and this occurs in the presence of accelerated FFA flux and oxidation.
- Published
- 2018
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13. One Size Fits All? Ethnicity and Electrocardiographic Criteria for Cardiac Hypertrophy.
- Author
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Chacko S and Redfearn D
- Subjects
- Arrhythmias, Cardiac, Cardiomegaly, Electrocardiography, Humans, Ethnicity, Hypertrophy, Left Ventricular
- Published
- 2018
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14. Radiotherapy for Patients with Cardiovascular Implantable Electronic Devices: A Review.
- Author
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Yeung C, Chacko S, Glover B, Campbell D, Crystal E, Ben-Dov N, and Baranchuk A
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- Female, Humans, Male, Monitoring, Physiologic, Neoplasms pathology, Patient Safety, Randomized Controlled Trials as Topic, Risk Assessment, Defibrillators, Implantable, Neoplasms radiotherapy, Pacemaker, Artificial, Prosthesis Failure etiology, Radiotherapy adverse effects
- Abstract
Because cardiovascular implantable electronic devices are increasingly indicated in older patients, and the burden of cancer is rising with the growth and aging of the world population, the management of patients with cardiac devices who require radiotherapy for cancer treatment is a timely concern. Device malfunctions might occur in as high as 3% of radiotherapy courses, posing a substantial issue in clinical practice. A nonsystematic comprehensive review was undertaken. We searched PubMed and the MEDLINE database for randomized controlled trials, meta-analyses, systematic reviews, observational studies, in vitro/in vivo studies, and case reports. Articles were selected by 2 independent reviewers, and emphasis was given to information of interest to a general medical readership. The pathophysiology and predictors of cardiovascular implantable electronic device malfunction due to radiotherapy are reviewed, recommendations for the management of patients with such devices undergoing radiotherapy are summarized, and the clinical significance and future directions of this field are discussed. Radiotherapy-induced device malfunctions are rare, but because of the potential complications, the development of evidence-based guidelines for the management of patients with cardiovascular implantable electronic devices undergoing radiotherapy is a timely concern., (Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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15. Mapping unmet supportive care needs, quality-of-life perceptions and current symptoms in cancer survivors across the Asia-Pacific region: results from the International STEP Study.
- Author
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Molassiotis A, Yates P, Li Q, So WKW, Pongthavornkamol K, Pittayapan P, Komatsu H, Thandar M, Yi M, Titus Chacko S, Lopez V, Butcon J, Wyld D, and Chan RJ
- Subjects
- Asia, Australia, Cross-Sectional Studies, Female, Humans, Male, Middle Aged, Palliative Care methods, Quality of Life, Cancer Survivors psychology, Health Services Needs and Demand, Needs Assessment, Neoplasms psychology, Neoplasms therapy
- Abstract
Background: To assess the supportive care needs, quality of life (QoL) and symptoms of patients with cancer after the end of first-line treatments and into survivorship in Asian countries using Australian data as benchmark., Patients and Methods: A cross-sectional survey was carried out in Australia and eight high-income (HICs) and low-/middle-income (LMICs) Asian countries (China, Japan, Hong Kong SAR, South Korea, Myanmar, Thailand, India, Philippines) using validated scales (Cancer Survivors Unmet Needs scale), physical-symptom concerns (Cancer Survivors Survey of Needs subscale) and a single-item measure of global QoL perception., Results: Data were collected from 1873 patients. QoL was highest in Australia and all other countries had significantly lower QoL than Australia (all P < 0.001). One-quarter of the patients reported low QoL (scores 1-3/10). The most frequently reported symptoms were fatigue (66.6%), loss of strength (61.8%), pain (61.6%), sleep disturbance (60.1%), and weight changes (57.7%), with no difference in symptom experience between Australian data and all other countries, or between HICs and LMICs. Unmet needs of moderate/strong level were particularly high in all aspects assessed, particularly in the area of existential survivorship (psychosocial care) and receiving comprehensive cancer care. Australia and HICs were similar in terms of unmet needs (all low), but LMICs had a significantly higher number of needs both compared with Australia and HICs (all P < 0.001)., Conclusion: Health care systems in Asian countries need to re-think and prioritize survivorship cancer care and put action plans in place to overcome some of the challenges surrounding the delivery of optimal supportive cancer care, use available resource-stratified guidelines for supportive care and test efficient and cost-effective models of survivorship care., (© The Author 2017. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2017
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16. Targeting the intersubunit cavity of Plasmodium falciparum glutathione reductase by a novel natural inhibitor: computational and experimental evidence.
- Author
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Tyagi C, Bathke J, Goyal S, Fischer M, Dahse HM, Chacko S, Becker K, and Grover A
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- Antimalarials adverse effects, Antimalarials pharmacology, Drug Evaluation, Preclinical methods, Enzyme Inhibitors adverse effects, High-Throughput Screening Assays methods, Human Umbilical Vein Endothelial Cells drug effects, Humans, K562 Cells, Models, Molecular, Molecular Dynamics Simulation, Plasmodium falciparum drug effects, Protein Subunits, Enzyme Inhibitors chemistry, Enzyme Inhibitors pharmacology, Glutathione Reductase antagonists & inhibitors, Glutathione Reductase chemistry, Plasmodium falciparum enzymology
- Abstract
Glutathione reductase (GR), a homodimeric FAD-dependent disulfide reductase, is essential for redox homeostasis of the malaria parasite Plasmodium falciparum and has been proposed as an antimalarial drug target. In this study we performed a virtual screening against PfGR, using the structures of about 170,000 natural compounds. Analysis of the two top-scoring molecules, TTB and EPB, indicated that these ligands are likely to interact with the homodimer intersubunit cavity of PfGR with high binding energy scores of -9.67 and -9.60kcal/mol, respectively. Both compounds had a lower affinity for human GR due to differences in structure and electrostatic properties. In order to assess the putative interactions in motion, molecular dynamics simulations were carried out for 30ns, resulting in TTB being more dynamically and structurally favored than EPB. A closely related compound MDPI 21618 was tested on recombinant PfGR and hGR, resulting in IC50 values of 11.3±2.5μM and 10.2±1.7μM, respectively. Kinetic characterization of MDPI 21618 on PfGR revealed a mixed-type inhibition with respect to glutathione disulfide (Ki=9.7±2.3μM) and an uncompetitive inhibition with respect to NADPH. Furthermore, MDPI 21618 was found to inhibit the growth of the chloroquine-sensitive P. falciparum strain 3D7 with an IC50 of 3.2±1.9μM and the chloroquine-resistant Dd2 strain with an IC50 of 3.2+1.6μM. In drug combination assays with chloroquine, artemisinin, or mefloquine MDPI 21618 showed an antagonistic action, which might suggest partially overlapping routes of action. This study further substantiates research on PfGR as a potential antimalarial drug target., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
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17. New generation lipid emulsions prevent PNALD in chronic parenterally fed preterm pigs.
- Author
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Vlaardingerbroek H, Ng K, Stoll B, Benight N, Chacko S, Kluijtmans LA, Kulik W, Squires EJ, Olutoye O, Schady D, Finegold ML, van Goudoever JB, and Burrin DG
- Subjects
- Animals, Animals, Newborn, Blotting, Western, Cells, Cultured, Cholestenones blood, Cholesterol 7-alpha-Hydroxylase genetics, Cholesterol 7-alpha-Hydroxylase metabolism, Female, Fish Oils administration & dosage, Gene Expression drug effects, Humans, Lipids administration & dosage, Lipids chemistry, Liver Diseases etiology, Olive Oil, Parenteral Nutrition adverse effects, Plant Oils administration & dosage, Pregnancy, Premature Birth veterinary, Reverse Transcriptase Polymerase Chain Reaction, Soybean Oil administration & dosage, Swine, Swine Diseases etiology, Triglycerides administration & dosage, gamma-Glutamyltransferase blood, Fat Emulsions, Intravenous administration & dosage, Liver Diseases prevention & control, Parenteral Nutrition methods, Swine Diseases prevention & control
- Abstract
Total parenteral nutrition (TPN) is associated with the development of parenteral nutrition-associated liver disease (PNALD) in infants. Fish oil-based lipid emulsions can reverse PNALD, yet it is unknown if they can prevent PNALD. We studied preterm pigs administered TPN for 14 days with either 100% soybean oil (IL), 100% fish oil (OV), or a mixture of soybean oil, medium chain triglycerides (MCTs), olive oil, and fish oil (SL); a group was fed formula enterally (ENT). In TPN-fed pigs, serum direct bilirubin, gamma glutamyl transferase (GGT), and plasma bile acids increased after the 14 day treatment but were highest in IL pigs. All TPN pigs had suppressed hepatic expression of farnesoid X receptor (FXR), cholesterol 7-hydroxylase (CYP7A1), and plasma 7α-hydroxy-4-cholesten-3-one (C4) concentrations, yet hepatic CYP7A1 protein abundance was increased only in the IL versus ENT group. Organic solute transporter alpha (OSTα) gene expression was the highest in the IL group and paralleled plasma bile acid levels. In cultured hepatocytes, bile acid-induced bile salt export pump (BSEP) expression was inhibited by phytosterol treatment. We show that TPN-fed pigs given soybean oil developed cholestasis and steatosis that was prevented with both OV and SL emulsions. Due to the presence of phytosterols in the SL emulsion, the differences in cholestasis and liver injury among lipid emulsion groups in vivo were weakly correlated with plasma and hepatic phytosterol content.
- Published
- 2014
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18. Resisting resistant Mycobacterium tuberculosis naturally: mechanistic insights into the inhibition of the parasite's sole signal peptidase Leader peptidase B.
- Author
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Dhiman H, Dhanjal JK, Sharma S, Chacko S, Grover S, and Grover A
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- Amino Acid Sequence, Antitubercular Agents chemistry, Bacterial Proteins antagonists & inhibitors, Bacterial Proteins chemistry, Biological Products chemistry, Caffeic Acids pharmacology, Catalytic Domain, Chromones pharmacology, Databases, Pharmaceutical, Disaccharides pharmacology, Enzyme Activation, High-Throughput Screening Assays, Ligands, Membrane Proteins chemistry, Molecular Dynamics Simulation, Mycobacterium tuberculosis chemistry, Mycobacterium tuberculosis enzymology, Protein Conformation, Protein Interaction Mapping, Protein Stability, Protein Structure, Tertiary, Serine Endopeptidases chemistry, Antitubercular Agents pharmacology, Drug Resistance, Multiple, Bacterial, Membrane Proteins antagonists & inhibitors, Mycobacterium tuberculosis drug effects
- Abstract
Tuberculosis (TB) is the second highest cause of mortality after HIV/AIDS and is one of the leading public health problems worldwide. The growing resistance to anti-TB drugs and the recalcitrant nature of tenacious infections present arduous challenges for the treatment of TB. Thus, the need to develop therapeutics against novel drug targets to help overcome multi-drug resistant TB is inevitable. Leader peptidase B (LepB), the sole signal peptidase of Mycobacterium tuberculosis (MTb), is one such potential drug target. The present work aims at identifying potential inhibitors of LepB, so as to repress the formation of the functional proteins essential for the growth and pathogenesis of MTb. In this study, we screened a large dataset of natural compounds against LepB using a high throughput approach. The screening was directed toward a binding pocket consisting of residues, some of which are critical for the catalytic activity of the enzyme, while others are part of the conserved domains of the signal peptidases. We also carried out molecular dynamics simulations of the two top-scoring compounds in order to study their molecular interactions with the active site functional residues of LepB and also to assess their dynamic behavior. We report herein two prospective non-covalent type inhibitory drugs of natural origin which are active against tuberculosis. These lead molecules possess improved binding properties, have low toxicity and are specific against MTb., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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19. Reducing glucose infusion safely prevents hyperglycemia in post-surgical children.
- Author
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Verbruggen SC, de Betue CT, Schierbeek H, Chacko S, van Adrichem LN, Verhoeven J, van Goudoever JB, and Joosten KF
- Subjects
- Amino Acids blood, Amino Acids metabolism, Blood Glucose analysis, Blood Glucose metabolism, Cross-Over Studies, Female, Humans, Infant, Infusions, Intravenous, Male, Statistics, Nonparametric, Craniosynostoses surgery, Glucose administration & dosage, Hyperglycemia prevention & control
- Abstract
Background & Aims: To investigate the effects of two different glucose infusions on glucose homeostasis and amino acid metabolism in post-surgical children., Methods: This randomized crossover study evaluated glucose and amino acid metabolism in eight children (age 9.8 ± 1.9 months, weight 9.5 ± 1.1 kg) admitted to a pediatric intensive care unit in a tertiary university hospital after surgical correction for non-syndromal craniosynostosis. Patients were randomized to receive low (LG; 2.5 mg kg(-1) min(-1)) and standard (SG; 5.0 mg kg(-1) min(-1)) glucose infusion in a crossover setting. After a bolus (4 g kg(-1)) of deuterium oxide, we conducted a primed, constant, 8 h tracer infusion with [6,6-²H₂]Glucose, [1-¹³C]Leucine, [ring-²H₅]Phenylalanine and [3,3-²H₂]Tyrosine., Results: SG resulted in hyperglycemia (defined as > 6.1 mmol L(-1)), while during LG plasma glucose levels were normoglycemic (5.9 ± 0.6 vs. 7.5 ± 1.7 mmol L(-1); LG vs. SG respectively, p = 0.02). Hypoglycemia did not occur during LG infusion. Endogenous glucose production was not fully suppressed during the hyperglycemic state under SG and increased with reduced glucose infusion (2.6 ± 1.5 vs. 1.1 ± 1.4 mg kg(-1) min(-1); LG vs. SG; p = 0.05). Whole body protein balance derived from leucine and phenylalanine kinetics was slightly negative but not further affected with a decrease in glucose infusion., Conclusions: The current recommended glucose infusion induces hyperglycemia in post-surgical children. A reduced glucose infusion safely reduced high glucose levels, while children were capable to sustain normoglycemia with increased endogenous glucose production. The reduced glucose infusion did not exacerbate the mild catabolic state in which the patients were., (2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
20. Transcriptional repression of Caveolin-1 (CAV1) gene expression by GATA-6 in bladder smooth muscle hypertrophy in mice and human beings.
- Author
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Boopathi E, Gomes CM, Goldfarb R, John M, Srinivasan VG, Alanzi J, Malkowicz SB, Kathuria H, Zderic SA, Wein AJ, and Chacko S
- Subjects
- Aged, Animals, Blotting, Western, Caveolin 1 genetics, Chromatin Immunoprecipitation, GATA6 Transcription Factor metabolism, Gene Expression, Gene Expression Regulation, Humans, Hypertrophy, Immunohistochemistry, Male, Mice, Microscopy, Confocal, Middle Aged, Muscle, Smooth metabolism, Promoter Regions, Genetic, Prostatic Hyperplasia complications, Reverse Transcriptase Polymerase Chain Reaction, Urinary Bladder Diseases metabolism, Urinary Bladder Diseases pathology, Urinary Bladder Neck Obstruction etiology, Urinary Bladder Neck Obstruction genetics, Urinary Bladder Neck Obstruction pathology, Caveolin 1 biosynthesis, GATA6 Transcription Factor genetics, Muscle, Smooth pathology, Urinary Bladder Diseases genetics
- Abstract
Hypertrophy occurs in urinary bladder wall smooth muscle (BSM) in men with partial bladder outlet obstruction (PBOO) caused by benign prostatic hyperplasia (BPH) and in animal models of PBOO. Hypertrophied BSM from the rabbit model exhibits down-regulation of caveolin-1, a structural and functional protein of caveolae that function as signaling platforms to mediate interaction between receptor proteins and adaptor and effector molecules to regulate signal generation, amplification, and diversification. Caveolin-1 expression is diminished in PBOO-induced BSM hypertrophy in mice and in men with BPH. The proximal promoter of the human and mouse caveolin-1 (CAV1) gene was characterized, and it was observed that the transcription factor GATA-6 binds this promoter, causing reduced expression of caveolin-1. Furthermore, caveolin-1 expression levels inversely correlate with the abundance of GATA-6 in BSM hypertrophy in mice and human beings. Silencing of GATA6 gene expression up-regulates caveolin-1 expression, whereas overexpression of GATA-6 protein sustains the transcriptional repression of caveolin-1 in bladder smooth muscle cells. Together, these data suggest that GATA-6 acts as a transcriptional repressor of CAV1 gene expression in PBOO-induced BSM hypertrophy in men and mice. GATA-6-induced transcriptional repression represents a new regulatory mechanism of CAV1 gene expression in pathologic BSM, and may serve as a target for new therapy for BPH-induced bladder dysfunction in aging men., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
21. Using the web for recruitment, screen, tracking, data management, and quality control in a dietary assessment clinical validation trial.
- Author
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Arab L, Hahn H, Henry J, Chacko S, Winter A, and Cambou MC
- Subjects
- Adult, Aged, Clinical Trials as Topic, Computer Security, Data Collection methods, Feeding Behavior, Female, Humans, Information Storage and Retrieval, Male, Middle Aged, Surveys and Questionnaires, Young Adult, Diet Surveys, Internet, Mass Screening, Patient Selection, Quality Control
- Abstract
Screening and tracking subjects and data management in clinical trials require significant investments in manpower that can be reduced through the use of web-based systems. To support a validation trial of various dietary assessment tools that required multiple clinic visits and eight repeats of online assessments, we developed an interactive web-based system to automate all levels of management of a biomarker-based clinical trial. The "Energetics System" was developed to support 1) the work of the study coordinator in recruiting, screening and tracking subject flow, 2) the need of the principal investigator to review study progress, and 3) continuous data analysis. The system was designed to automate web-based self-screening into the trial. It supported scheduling tasks and triggered tailored messaging for late and non-responders. For the investigators, it provided real-time status overviews on all subjects, created electronic case reports, supported data queries and prepared analytic data files. Encryption and multi-level password protection were used to insure data privacy. The system was programmed iteratively and required six months of a web programmer's time along with active team engagement. In this study the enhancement in speed and efficiency of recruitment and quality of data collection as a result of this system outweighed the initial investment. Web-based systems have the potential to streamline the process of recruitment and day-to-day management of clinical trials in addition to improving efficiency and quality. Because of their added value they should be considered for trials of moderate size or complexity., (Copyright 2009 Elsevier Inc. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
22. Electrocardiogram changes causing a diagnostic dilemma.
- Author
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Hamid T, Nair S, Chacko S, and Clarke B
- Subjects
- Humans, Male, Middle Aged, Myocardial Ischemia etiology, Pulmonary Embolism complications, Pulmonary Embolism drug therapy, Thrombolytic Therapy, Electrocardiography, Pulmonary Embolism diagnosis
- Published
- 2009
- Full Text
- View/download PDF
23. Smooth muscle hypertrophy following partial bladder outlet obstruction is associated with overexpression of non-muscle caldesmon.
- Author
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Zhang EY, Stein R, Chang S, Zheng Y, Zderic SA, Wein AJ, and Chacko S
- Subjects
- Animals, Biomarkers, Blotting, Western, Hypertrophy metabolism, Hypertrophy pathology, Immunohistochemistry, Male, Muscle, Smooth metabolism, Rabbits, Reverse Transcriptase Polymerase Chain Reaction, Up-Regulation, Urinary Bladder pathology, Urinary Bladder physiology, Urinary Bladder Neck Obstruction metabolism, Urodynamics, Calmodulin-Binding Proteins biosynthesis, Muscle, Smooth pathology, Urinary Bladder Neck Obstruction pathology
- Abstract
Partial bladder outlet obstruction (PBOO) induces remodeling of urinary bladder smooth muscle (detrusor). We demonstrate an increase in bladder wall mass, muscle bundle size, and a threefold increase in the cross-sectional area of detrusor myocytes following PBOO in male New Zealand White rabbits compared to that of controls. Some bladders with detrusor hypertrophy function close to normal (compensated), whereas others were dysfunctional (decompensated), showing high intravesical pressure, large residual urine volume, and voiding difficulty. We analyzed the expression of smooth muscle-specific caldesmon (h-CaD) and non-muscle (l-CaD) by Western blotting, RT-PCR, and real-time PCR. The expression of l-CaD is increased significantly at the mRNA and protein levels in the decompensated bladders compared to that of normal and compensated bladders. The CaD was also co-localized with myosin containing cytoplasmic fibrils in cells dissociated from obstructed bladders and cultured overnight. Our data show that the inability of decompensated bladders to empty, despite detrusor hypertrophy, is associated with an overexpression of l-CaD. The level of l-CaD overexpression might be a useful marker to estimate the degree of detrusor remodeling and contractile dysfunction in PBOO.
- Published
- 2004
- Full Text
- View/download PDF
24. Monoterpenoids from the seeds of Heracleum candolleanum.
- Author
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Chacko S, Sethuraman MG, and George V
- Subjects
- Bicyclic Monoterpenes, Camphanes chemistry, Humans, Magnetic Resonance Spectroscopy, Seeds, Terpenes chemistry, Apiaceae, Camphanes isolation & purification, Plants, Medicinal, Terpenes isolation & purification
- Abstract
The isolation and NMR spectra of 2-exo,3-endo-camphanediol (1) and 2-pinene-4,10-diol (2) from the seeds of Heracleum candolleanum are reported.
- Published
- 2000
- Full Text
- View/download PDF
25. The X-ray crystal structure of a Valpha2.6Jalpha38 mouse T cell receptor domain at 2.5 A resolution: alternate modes of dimerization and crystal packing.
- Author
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Plaksin D, Chacko S, Navaza J, Margulies DH, and Padlan EA
- Subjects
- Amino Acid Sequence, Animals, Crystallography, X-Ray, Dimerization, Mice, Models, Molecular, Molecular Sequence Data, Protein Conformation, Receptors, Antigen, T-Cell, alpha-beta chemistry
- Abstract
We describe here the structure of a murine T cell receptor (TCR) Valpha2.6Jalpha38 (TCRAV2S6J38) domain, derived from a T cell hybridoma with specificity for the H-2Ddmajor histocompatibility complex class I molecule bound to a decamer peptide, P18-I10, from the HIV envelope glycoprotein gp120, determined by X-ray crystallography at 2.5 A resolution. Unlike other TCR Valpha domains that have been studied in isolation, this one does not dimerize in solution at concentrations below 1 mM, and the crystal fails to show dimer contacts that are likely to be physiological. In comparison to other Valpha domains, this Valpha2.6 shows great similarity in the packing of its core residues, and exhibits the same immunoglobulin-like fold characteristic of other TCR Valpha domains. There is good electron density in all three complementarity-determining regions (CDRs), where the differences between this Valpha domain and others are most pronounced, in particular in CDR3. Examination of crystal contacts reveals an association of Valpha domains distinct from those previously seen. Comparison with other Valpha domain structures reveals variability in all loop regions, as well as in the first beta strand where placement and configuration of a proline residue at position 6, 7, 8, or 9 affects the backbone structure. The great variation in CDR3 conformations among TCR structures is consistent with an evolving view that CDR3 of TCR plays a plastic role in the interaction of the TCR with the MHC/peptide complex as well as with CDR3 of the paired TCR chain., (Copyright 1999 Academic Press.)
- Published
- 1999
- Full Text
- View/download PDF
26. Pro-inflammatory cytokines induce expression of matrix-metabolizing enzymes in human cervical smooth muscle cells.
- Author
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Watari M, Watari H, DiSanto ME, Chacko S, Shi GP, and Strauss JF 3rd
- Subjects
- Blotting, Western, Cathepsins biosynthesis, Cathepsins metabolism, Cells, Cultured, Cervix Uteri metabolism, Dose-Response Relationship, Drug, Endopeptidases metabolism, Enzyme Induction drug effects, Female, Humans, Immunohistochemistry, Metalloendopeptidases biosynthesis, Metalloendopeptidases metabolism, Muscle, Smooth enzymology, Muscle, Smooth metabolism, Protease Inhibitors metabolism, RNA, Messenger biosynthesis, Reverse Transcriptase Polymerase Chain Reaction, Tissue Inhibitor of Metalloproteinase-1 biosynthesis, Tissue Inhibitor of Metalloproteinase-1 metabolism, Tissue Inhibitor of Metalloproteinase-2 biosynthesis, Tissue Inhibitor of Metalloproteinase-2 metabolism, Cervix Uteri enzymology, Endopeptidases biosynthesis, Interleukin-1 pharmacology, Muscle, Smooth drug effects, Tumor Necrosis Factor-alpha pharmacology
- Abstract
The process of cervical ripening has been likened to an inflammatory reaction associated with the catabolism of cervical extracellular matrix by enzymes released from infiltrating leukocytes. We hypothesized that smooth muscle cells in the cervix also participate in this process and that pro-inflammatory cytokines act on cervical smooth muscle cells (CSMC) to provoke the expression of matrix-degrading enzymes. We treated primary cultures of human CSMC with tumor necrosis factor-alpha (TNF-alpha) and examined expression of the elastinolytic enzyme, cathepsin S, the collagen metabolizing matrix metalloproteinases (MMP)-1, -3, -9, and the tissue inhibitor of metalloproteinase (TIMP)-1 and -2. A time course analysis revealed that 10 ng/ml of TNF-alpha induced cathepsin S, MMP-1, -3, and -9 mRNA expression with the maximal response observed after 24-48 hours. TNF-alpha induced cathepsin S, MMP-1, -3, and -9 mRNA expression in a dose-dependent manner: the maximal effect was observed at a concentration of 10 ng/ml, with appreciable increases observed at concentrations of 0.1 to 1.0 ng/ml. In contrast, TIMP-1 and -2 mRNAs were not significantly increased by TNF-alpha treatment. Interleukin-1beta produced a pattern of gene expression in the CSMC similar to that observed following TNF-alpha treatment. Western blot analysis and zymography confirmed the induction of proMMP-1, -3, and -9 in response to TNF-alpha, but MMP-2 immunoreactivity and zymographic activity were unaffected. TNF-alpha increased secretion of procathepsin S, but did not affect TIMP-1 and reduced TIMP-2 production. We conclude that CSMC are targets of pro-inflammatory cytokines, which induce a repertoire of enzymes capable of degrading the cervical extracellular matrix. The induction of these enzymes may facilitate the normal ripening of the cervix at term and participate in the premature cervical changes associated with preterm labor.
- Published
- 1999
- Full Text
- View/download PDF
27. Comparison of the effects of calponin and a 38-kDa caldesmon fragment on formation of the "strong-binding" state in ghost muscle fibers.
- Author
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Borovikov YS, Khoroshev MI, and Chacko S
- Subjects
- Animals, Calcium-Binding Proteins pharmacology, Calmodulin-Binding Proteins pharmacology, Chickens, Cross-Linking Reagents pharmacology, Ethylmaleimide pharmacology, Gizzard, Avian, Maleimides pharmacology, Microfilament Proteins, Muscle Proteins metabolism, Muscle Proteins pharmacology, Muscle, Smooth physiology, Myosins metabolism, Peptide Fragments metabolism, Peptide Fragments pharmacology, Protein Binding, Protein Conformation, Rabbits, Calponins, Actins chemistry, Actins metabolism, Calcium-Binding Proteins metabolism, Calmodulin-Binding Proteins metabolism, Muscle Fibers, Skeletal physiology, Muscle, Skeletal physiology
- Abstract
We studied the conformational changes in actin filaments induced by the binding of calponin or a 38-kDa fragment of caldesmon, two actin-binding proteins known to inhibit actin-activated ATP hydrolysis by phosphorylated smooth muscle myosin. The F-actinin myosin-free muscle fibers (ghost fibers) was labeled with fluorescein-5-maleimide and the conformational change in actin was determined by polarized fluorimetry. Data show that both calponin and the 38-kDa caldesmon fragment inhibit the conformational changes in F-actin that are compatible with the "strong-binding" state between myosin heads and actin. Tropomyosin slightly reduced the effect produced by calponin, but enhances the effect produced by the 38-kDa caldesmon fragment.
- Published
- 1996
- Full Text
- View/download PDF
28. Structure of an antibody-lysozyme complex unexpected effect of conservative mutation.
- Author
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Chacko S, Silverton E, Kam-Morgan L, Smith-Gill S, Cohen G, and Davies D
- Subjects
- Animals, Aprotinin chemistry, Arginine genetics, Binding Sites genetics, Chickens, Crystallography, Hydrogen Bonding, Immunoglobulin Fab Fragments genetics, Immunoglobulin Fab Fragments immunology, Macromolecular Substances, Models, Molecular, Muramidase genetics, Muramidase immunology, Mutagenesis, Site-Directed, Protein Binding, Recombinant Proteins chemistry, Recombinant Proteins immunology, Trypsin chemistry, Water chemistry, Immunoglobulin Fab Fragments chemistry, Muramidase chemistry, Mutation
- Abstract
The structure of the complex between the Fab HyHEL-5 and chicken lysozyme revealed a large interface region containing 23 lysozyme and 28 Fab residues. Arg68 of the lysozyme is centrally placed in this interface and theoretical studies together with binding assays of this Fab to different avian lysozymes have previously shown that this arginine residue is an important contributor to the binding. The Arg68-->Lys mutant binds 10(3) times less well to the HyHEL-5 Fab. We have examined the refined crystal structure of the complex of this mutant lysozyme with the Fab. No global changes occur, but there is an introduction of a new water molecule into the interface that mediates the hydrogen bonding interactions between the lysine and residues on the Fab. These data are compared with the effects of similar changes on the inhibition of serine proteases such as trypsin where the energetic effects of this substitution are small.
- Published
- 1995
- Full Text
- View/download PDF
29. The mechanism for the inhibition of actin-activated ATPase of smooth muscle heavy meromyosin by calponin.
- Author
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Horiuchi KY and Chacko S
- Subjects
- Animals, Calcium-Binding Proteins metabolism, Chickens, Enzyme Activation, Gizzard, Avian metabolism, Kinetics, Microfilament Proteins, Muscle Proteins pharmacology, Protein Binding, Calponins, Actins metabolism, Ca(2+) Mg(2+)-ATPase antagonists & inhibitors, Calcium-Binding Proteins pharmacology, Muscle, Smooth metabolism, Myosin Subfragments antagonists & inhibitors
- Abstract
Calponin, an actin-binding protein, inhibited the acto-heavy meromyosin (HMM) MgATPase and lowered the binding of HMM to actin. The amount of calponin bound to actin or tropomyosin-actin was the same when the ATPase was inhibited 80-90%. While the KATPase was diminished only less than 2-fold in the presence of calponin, the Vmax was decreased 6-fold and 2-fold with actin and tropomyosin-actin, respectively. A comparison of the kinetic constants for the ATP hydrolysis obtained in the presence of actin-calponin and tropomyosin-actin-calponin revealed that the tropomyosin augmented the Vmax 5-fold from the inhibited level, but there was no effect on the KATPase.
- Published
- 1991
- Full Text
- View/download PDF
30. Modulation of smooth muscle actomyosin ATPase by thin filament associated proteins.
- Author
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Horiuchi KY, Miyata H, and Chacko S
- Subjects
- Actins metabolism, Animals, Ca(2+) Mg(2+)-ATPase metabolism, Calcium metabolism, Calmodulin metabolism, Chickens, Kinetics, Phosphorylation, Tropomyosin metabolism, Actomyosin metabolism, Adenosine Triphosphatases metabolism, Calmodulin-Binding Proteins pharmacology, Muscle, Smooth enzymology
- Abstract
Caldesmon binds equally to both gizzard actin and actin containing stoichiometric amounts of bound tropomyosin. The binding of caldesmon to actin inhibits the actin-activation of the Mg-ATPase activity of phosphorylated myosin only when the actin contains bound tropomyosin. The reversal of this inhibition requires Ca2+-calmodulin; but it occurs without complete release of bound caldesmon. Although phosphorylation of the caldesmon occurs during the ATPase assay, a direct correlation between caldesmon phosphorylation and the release of the inhibited actomyosin ATPase is not consistently observed.
- Published
- 1986
- Full Text
- View/download PDF
31. Health care in transition in Kerala.
- Author
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Chacko S
- Subjects
- Hospitals, Federal standards, Hospitals, Proprietary standards, India, United States, Delivery of Health Care trends, Health Services trends
- Published
- 1989
- Full Text
- View/download PDF
32. Collagen polymorphism in cell cultures derived from guinea pig aortic smooth muscle: comparison with three populations of fibroblasts.
- Author
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Mayne R, Vail MS, Miller EJ, Blose SH, and Chacko S
- Subjects
- Aorta, Cells, Cultured, Collagen analysis, Disulfides analysis, Molecular Weight, Peptides analysis, Collagen biosynthesis, Fibroblasts metabolism, Muscle, Smooth metabolism
- Published
- 1977
- Full Text
- View/download PDF
33. Characteristics of the myosin and tropomyosin binding regions of the smooth muscle caldesmon.
- Author
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Katayama E, Horiuchi KY, and Chacko S
- Subjects
- Actins metabolism, Actins pharmacology, Adenosine Triphosphatases antagonists & inhibitors, Adenosine Triphosphatases metabolism, Animals, Binding Sites, Calmodulin-Binding Proteins pharmacology, Chickens, Chromatography, Affinity, Chymotrypsin metabolism, Electrophoresis, Polyacrylamide Gel, Gizzard, Avian analysis, Molecular Weight, Myosin Subfragments metabolism, Peptide Fragments metabolism, Peptide Fragments pharmacology, Calmodulin-Binding Proteins metabolism, Myosins metabolism, Tropomyosin metabolism
- Abstract
Limited digestion of caldesmon by alpha-chymotrypsin generates mainly 110, 80, 60, 38, and 28 kDa fragments. Affinity chromatography of these fragments on columns immobilized with myosin, HMM, or tropomyosin showed that the bound fraction from these columns was similar and it contained 110, 80, 60 and 28 kDa fragments. These fragments did not bind to myosin filaments, acto-HMM, actin or tropomyosin-actin in the solution, and they had no effect on the actin-activated ATPase of HMM. In contrast, the flow-through fraction from these affinity columns inhibited the actin-activated ATPase. Binding studies revealed that the 38 kDa fragment and its break down products bound to actin and tropomyosin-actin, and they were released partially from actin by calmodulin with a concomitant increase in the ATPase activity. These results indicate that, unlike the actin binding domain, the myosin and tropomyosin binding domains require the caldesmon molecule to be intact in order to exert their effects on the protein-protein interaction.
- Published
- 1989
- Full Text
- View/download PDF
34. The effect of 5-bromodeoxyuridine (BrdU) on cardiac muscle differentiation.
- Author
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Chacko S and Joseph X
- Subjects
- Animals, Autoradiography, Cell Differentiation drug effects, Cell Division drug effects, Cells, Cultured, Chick Embryo, Fluorescent Antibody Technique, Heart embryology, Mesoderm cytology, Mesoderm drug effects, Myocardium cytology, Phenotype, Thymidine pharmacology, Tritium, Bromodeoxyuridine pharmacology, Heart drug effects
- Published
- 1974
- Full Text
- View/download PDF
35. The effect of leiotonin fraction on stably phosphorylated smooth muscle myosin.
- Author
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Chacko S, Heaslip RJ, and Ebashi S
- Subjects
- Actins metabolism, Actomyosin metabolism, Animals, Calcium metabolism, Chickens, Enzyme Activation, Gizzard, Avian, Phosphorylation, Tropomyosin metabolism, Adenosine Triphosphatases metabolism, Muscle Proteins physiology, Muscle, Smooth enzymology, Myosins metabolism
- Abstract
This study was designed to determine the effect of leiotonin on the actin-activation once the myosin is stably phosphorylated. Gizzard myosin was stably phosphorylated by ATP-gamma-S using the gizzard light chain kinase. Addition of leiotonin preparation to phosphorylated myosin reconstituted with actin and tropomyosin did not alter the ATPase activity. Furthermore, leiotonin did not confer the calcium sensitivity of the ATPase activity. These experiments show that the actin-activated ATPase activity of stably phosphorylated gizzard myosin is not altered by leiotonin.
- Published
- 1985
- Full Text
- View/download PDF
36. Myofibril organisation and mitosis in cultured cardiac muscle cells.
- Author
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Kelly AM and Chacko S
- Subjects
- Animals, Cell Nucleus ultrastructure, Cells, Cultured, Chick Embryo, Myocardial Contraction, Myocardium ultrastructure, Mitosis, Myocardium cytology, Myofibrils ultrastructure
- Published
- 1976
- Full Text
- View/download PDF
37. Suppression of chondrogenic expression in mixtures of normal chondrocytes and BUDR-altered chondrocytes grown in vitro.
- Author
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Chacko S, Holtzer S, and Holtzer H
- Subjects
- Animals, Chick Embryo, Culture Techniques, Kidney, Liver, Surface Properties, Bromodeoxyuridine pharmacology, Cartilage metabolism, Chondroitin biosynthesis
- Published
- 1969
- Full Text
- View/download PDF
38. DNA synthesis, mitosis, and differentiation in cardiac myogenesis.
- Author
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Chacko S
- Subjects
- Animals, Autoradiography, Chick Embryo, Clone Cells, In Vitro Techniques, Microscopy, Electron, Myocardium metabolism, Thymidine, Tritium, Cell Differentiation, DNA biosynthesis, Heart embryology, Mitosis, Myocardium cytology
- Published
- 1973
- Full Text
- View/download PDF
39. The loss of phenotypic traits by differentiated cells in vitro. VII. Effects of 5-bromodeoxyuridine and prolonged culturing on fine structure of chondrocytes.
- Author
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Anderson HC, Chacko S, Abbott J, and Holtzer H
- Subjects
- Animals, Cartilage drug effects, Cartilage embryology, Cell Differentiation, Chick Embryo, Collagen, In Vitro Techniques, Microscopy, Electron, Spine cytology, Spine embryology, Time Factors, Bromodeoxyuridine pharmacology, Cartilage cytology, Clone Cells, Connective Tissue Cells, Phenotype
- Published
- 1970
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