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Summary A library of well-characterized human induced pluripotent stem cell (hiPSC) lines from clinically healthy human subjects could serve as a useful resource of normal controls for in vitro human development, disease modeling, genotype-phenotype association studies, and drug response evaluation. We report generation and extensive characterization of a gender-balanced, racially/ethnically diverse library of hiPSC lines from 40 clinically healthy human individuals who range in age from 22 to 61 years. The hiPSCs match the karyotype and short tandem repeat identities of their parental fibroblasts, and have a transcription profile characteristic of pluripotent stem cells. We provide whole-genome sequencing data for one hiPSC clone from each individual, genomic ancestry determination, and analysis of mendelian disease genes and risks. We document similar transcriptomic profiles, single-cell RNA-sequencing-derived cell clusters, and physiology of cardiomyocytes differentiated from multiple independent hiPSC lines. This extensive characterization makes this hiPSC library a valuable resource for many studies on human biology., Highlights • A library of induced pluripotent stem cells from 40 healthy human subjects • Racially/ethnically diverse subjects of clinically well-characterized health • Whole-genome sequencing identifies variants of mild common phenotypes or incomplete penetrance • Similar physiology of cardiomyocytes from independent hiPSC clones and individuals, In this resource, Schaniel et al. report the generation and characterization of a gender-balanced, racially/ethnically diverse library of hiPSC lines from 40 clinically well-characterized healthy human individuals. The authors provide whole-genome sequencing data, ancestry determination, and analysis of mendelian disease genes and risks. Furthermore, similar physiology of cardiomyocytes differentiated from independent hiPSC clones derived from two individuals is documented.

Recent years have seen an increase in conversations in higher education around academic integrity. The subject of plagiarism in traditional written assessments has been much discussed and well researched. Considerably less is known about visual plagiarism. For the purposes of this chapter, we are defining “visuals” as mechanisms that convey meaning without articulation of, or dependence on language. Although some scholarly literature on visual plagiarism exists, there is a dearth of comprehensive literature on the topic and even less published are instructional or best-practice resources for instructors. Further complicating this topic are the differing ethical, legal, professional, and academic standards across fields. Here, we discuss practical ways to pre-emptively approach the topic of visual plagiarism through the education of faculty and students. We address prevention with suggestions for best practices in four distinct disciplines. Additionally, academic policy and administrative challenges are explored. Finally, we make recommendations for further research. This chapter will be of use both across Canada and globally, by providing a framework for defining and examining visual plagiarism in academic contexts and offering guidelines for pedagogical approaches to educate faculty, administration, and students on this important issue.

The purpose of this project was to provide a profile of DNA, RNA, and protein content in adipose tissue, which is relatively understudied in humans, to gain more insight into the amount of tissue that may be required for various analyses. Skeletal muscle tissue was also investigated to provide a direct comparison into potential differences between these two highly metabolically active tissues. Basal adipose and skeletal muscle tissue samples were obtained from 10 (7 M, 3 W) recreationally active participants [25 ± 1 yr; 84 ± 3 kg, maximal oxygen consumption (V̇o(2max)): 3.5 ± 0.2 L/min, body fat: 29 ± 2%]. DNA, RNA, and protein were extracted and subsequently analyzed for quantity and quality. DNA content of adipose and skeletal muscle tissue was 52 ± 14 and 189 ± 44 ng DNA·mg tissue(−1), respectively (P < 0.05). RNA content of adipose and skeletal muscle tissue was 46 ± 14 and 537 ± 72 ng RNA·mg tissue(−1), respectively (P < 0.05). Protein content of adipose and skeletal muscle tissue was 4 ± 1 and 177 ± 10 µg protein·mg tissue(−1), respectively (P < 0.05). In summary, human adipose had 28% of the DNA, 9% of the RNA, and 2% of the protein found in skeletal muscle per mg of tissue. This information should be useful across a wide range of human clinical investigation designs and various laboratory analyses. NEW & NOTEWORTHY This investigation studied DNA, RNA, and protein contents of adipose and skeletal muscle tissues from young active individuals. A series of optimization steps were investigated to aid in determining the optimal approach to extract high-yield and high-quality biomolecules. These findings contribute to the knowledge gap in adipose tissue requirements for molecular biology assays, which is of increasing importance due to the growing interest in adipose tissue research involving human exercise physiology research.

Prostaglandin (PG) E2 has been linked to increased inflammation and attenuated resistance exercise adaptations in skeletal muscle. Nonaspirin cyclooxygenase (COX) inhibitors have been shown to reduce these effects. This study examined the effect of low‐dose aspirin on skeletal muscle COX production of PGE2 at rest and following resistance exercise. Skeletal muscle (vastus lateralis) biopsies were taken from six individuals (4 M/2 W) before and 3.5 hr after a single bout of resistance exercise for ex vivo PGE2 production under control and low (10 μM)‐ or standard (100 μM)‐dose aspirin conditions. Sex‐specific effects of aspirin were also examined by combining the current findings with our previous similar ex vivo skeletal muscle investigations (n = 20, 10 M/10 W). Low‐dose aspirin inhibited skeletal muscle PGE2 production (p 0.05) and was not influenced by resistance exercise (p > 0.05) (overall effect: −18 ± 5%). Men and women had similar uninhibited skeletal muscle PGE2 production at rest (men: 1.97 ± 0.33, women: 1.96 ± 0.29 pg/mg wet weight/min; p > 0.05). However, skeletal muscle of men was 60% more sensitive to aspirin inhibition than women (p

Background Resistance exercise provides an effective stimulus for improving the metabolic plasticity of skeletal muscle, and the type of acute muscle contraction plays an important role in determining specific responses and adaptations. The purpose of the current investigation was to examine the effect of contraction order on metabolic responses by comparing monophasic concentric and eccentric squats versus a protocol incorporating alternated concentric and eccentric repetitions. Methods Twelve recreationally active men (21.1±1.1yr) performed three nearly identical squat protocols on separate days. Protocols varied only with contraction-type, including 4 sets x 10 reps concentric-only (CON), eccentric-only (ECC), and BOTH which alternated 5 concentric followed by 5 eccentric reps (CON-ECC; sets 1 and 3) and vice versa (ECC-CON; sets 2 and 4). The experimental trials were performed once weekly in a randomized, counterbalanced order, and expired gases were collected using a two-way non-rebreathing mask and oxygen consumption quantified with indirect calorimetry. Subjects raised (CON) and lowered (ECC) the load in 2s, and all sets (2min) and repetitions (8s) were separated by standardized rest intervals. Results From the BOTH protocol, the increase in metabolic rate was significantly greater (p≤0.05) during squats performed with CON-ECC order (0.60±0.11 L·min-1) compared to ECC-CON (0.44±0.07 L·min-1), but excess post-exercise oxygen consumption (EPOC) was opposite, with significantly greater metabolic rate during the 2-minute rest intervals after ECC-CON squats (0.46±0.09 L·min-1) compared to CON-ECC (0.25±0.05 L·min-1). Metabolic rates during and after squats were significantly greater (p±0.05) with CON (0.63±0.09; 0.49±0.10 L·min-1) compared to ECC (0.34±0.04; 0.20±0.04 L·min-1), respectively. Conclusions These data present an interesting paradigm regarding the contraction-dependent metabolic responses to monophasic resistance exercise and suggest a greater EPOC following concentric versus eccentric muscle actions.

In the pre–direct-acting antiviral era, hepatitis C virus (HCV) treatments were complex and largely managed by hepatologists, gastroenterologists, and infectious disease physicians. As direct-acting antivirals have driven up demand for treatment, the relative scarcity of these specialists has created a bottleneck effect, resulting in only a fraction of HCV-infected individuals offered treatment. The San Francisco Health Network is a safety net system of care. Its intervention was designed to be sustainable and scalable; with minimal time commitments for training providers, primary care–based HCV treatment increased 3-fold in a period of just over 3 years.

Background: Faculty focused on student success may look for opportunities to facilitate nursing student retention. Students commonly struggle with study skills, time management, and critical thinking in the nursing curriculum. This article presents the GROWTH ( G rowth, R eadiness, O pportunity, W ork, T ime management, and H abits) form, an open-ended question form aimed at the identification of affective, environment, and psychosocial variables known to impede nursing student success. Method: Faculty used the GROWTH form when meeting with students in the beginning of the prelicensure program. Results: Using the GROWTH form facilitates structured, focused faculty–student meetings and individualized action plans for students who are not achieving their desired level of academic performance. The GROWTH form also encourages students to take ownership of their own learning. Conclusion: Using the GROWTH form facilitates faculty–student meetings and encourages student self-reflection. Future research should investigate whether use of the GROWTH form has further implications for program progression and retention. [ J Nurs Educ. 2019;58(3):173–177.]

Volcanic activity can have a notable impact on glacier behaviour (dimensions and dynamics). This is evident from the palaeo-record, but is often difficult to observe for modern glaciers. However, documenting and, if possible, quantifying volcanic impacts on modern glaciers is important if we are to predict their future behaviour (including crucial ice masses such as the West Antarctic Ice Sheet) and to monitor and mitigate glacio-volcanic hazards such as floods (including jökulhlaups) and lahars. This review provides an assessment of volcanic impacts on the behaviour of modern glaciers (since AD 1800) by presenting and summarising a global dataset of documented examples. The study reveals that shorter-term (days-to-months) impacts are typically destructive, while longer-term (years-to-decades) are more likely protective (e.g., limiting climatically driven ice loss). However, because these events are difficult to observe, particularly before the widespread availability of global satellite data, their frequency and importance are likely underestimated. The study also highlights that because the frequency and nature of volcano-glacier interactions may change with time (e.g., glacier retreat may lead to an increase in explosive volcanic activity), predicting their future importance is difficult. Fortunately, over coming years, continued improvements in remotely sensed data will increase the frequency, and enhance the quality, of observations of volcanic impacts on glaciers, allowing an improved understanding of their past and future operation.

In the pre-direct-acting antiviral era, hepatitis C virus (HCV) treatments were complex and largely managed by hepatologists, gastroenterologists, and infectious disease physicians. As direct-acting antivirals have driven up demand for treatment, the relative scarcity of these specialists has created a bottleneck effect, resulting in only a fraction of HCV-infected individuals offered treatment. The San Francisco Health Network is a safety net system of care. Its intervention was designed to be sustainable and scalable; with minimal time commitments for training providers, primary care-based HCV treatment increased 3-fold in a period of just over 3 years.

Objective To determine whether sampled food blogs provide nutritionally balanced recipes. Methods Two entree recipes per season, per year (2010–2011) were selected from 6 highly ranked food blogs (n = 96). Food Processor Nutrition and Fitness software was used to analyze sodium, saturated fat, and energy content. Analysis was separated by protein type (vegetarian, poultry, red meat, and seafood). Results Recipes met energy recommendations but were excessive in saturated fat and sodium. Vegetarian and seafood recipes were significantly lower in risk nutrients compared with red meat and poultry recipes. Red meat recipes were not significantly different from poultry recipes for risk nutrients studied; poultry recipes were higher in sodium and energy compared with red meat recipes. Conclusions and Implications The public should be aware of the nutritional limitations of popular food blogs; dietitians could assist in modifying blog recipes for individuals and partner with bloggers to improve the nutritional profile of recipes.

Monitoring glacier fluctuations provides insights into changing glacial environments and recent climate change. The availability of satellite imagery offers the opportunity to view these changes for remote and inaccessible regions, often underrepresented in glacial inventories. Gaining an understanding of the ongoing changes in such regions is vital if a complete picture of glacial fluctuations globally is to be established. With this in mind, here we use satellite imagery (Landsat 7, 8 and ASTER) to conduct a multi-annual remote sensing survey of glacier fluctuations on the Kamchatka Peninsula (Eastern Russia) over the 2000–2014 period. Glacier margins were digitised manually, and reveal that in 2000, the peninsula was occupied by 676 glaciers, with a total exposed-ice area of 664.8 ± 23.9 km2. By 2014, the number of glaciers had increased to 766 (reflecting the fragmentation of larger glaciers), but their surface area had decreased to 465.1 ± 15.7 km2. This represents a ~ 30 % decline in total glacier surface area between 2000 and 2014, and a notable acceleration in the rate of area-loss since the late 20th century. Analysis of possible controls indicates that these glacier fluctuations were likely governed by variations in climate (particularly rising summer temperatures), though the response of individual glaciers was modulated by other (non-climatic) factors, principally glacier size and local shading.

Pompe disease is an autosomal recessive lysosomal storage disorder caused by a deficiency of the lysosomal enzyme acid α-glucosidase, responsible for the degradation of lysosomal glycogen. Absent or low levels of the enzyme leads to lysosomal glycogen accumulation in cardiac and skeletal muscle cells, resulting in progressive muscle weakness and death from cardiac or respiratory failure. Recombinant enzyme replacement and gene therapy are now being investigated as treatment modalities for this disease. A knockout mouse model for Pompe disease, induced by the disruption of exon 6 within the acid α-glucosidase gene, mimics the human disease and has been used to evaluate the efficacy of treatment modalities for clearing glycogen. However, for accurate histopathological assessment of glycogen clearance, maximal preservation of in situ lysosomal glycogen is essential. To improve retention of glycogen in Pompe tissues, several fixation and embedding regimens were evaluated. The best glycogen preservation was obtained when tissues fixed with 3% glutaraldehyde and postfixed with 1% osmium tetroxide were processed into epon-araldite. Preservation was confirmed by staining with the Periodic acid-Schiff's reaction and by electron microscopy. This methodology resulted in high-resolution light microscopy (HRLM) sections suitable for digital quantification of glycogen content in heart and skeletal muscle. Combining this method of tissue fixation with computer-assisted histomorphometry has provided us with what we believe is the most objective and reproducible means of evaluating histological glycogen load in Pompe disease.

Previous studies indicate that insulin-like growth factor-1 is an important neurotrophic agent and that decreases in brain concentrations of IGF-1 and the type 1 IGF receptor have an important role in the age-related decline in memory, neuronal function and possibly dendritic architecture. In this study, we assessed the effects of age and IGF-1 replacement on local cerebral glucose utilization (LCGU). Three groups of male Brown-Norway rats (7, 18 and 28 months of age) were implanted with Alzet minipumps and either saline or IGF-1 (50ng/0.5 microliter/hour) was infused into the lateral ventricle for 28 days. On day 28, LCGU was measured by infusion of 2-[(14)C]deoxyglucose during the dark phase of the light/dark cycle. Results indicate that glucose utilization significantly decreased with age throughout the brain including the anterior cingulate, sensorimotor and retrosplenial cortex, CA1, CA3 and dentate gyrus of hippocampus and several regions of the hypothalamus. Administration of IGF-1 to aged animals increased rates of LCGU in the anterior cingulate of the cortex (14.2%), CA1 region of the hippocampus (11.0%) and the arcuate nucleus of the hypothalamus (12.0%). Our results indicate that although glucose utilization decreases with age throughout the brain, the effects of IGF-1 infusion are manifest only in specific brain regions. Since IGF-1 has been shown to reverse the age-related decrease in memory, these results suggest that despite the wide distribution of the type 1 IGF receptor the actions of IGF-1 on glucose utilization are highly localized. Additionally, the close association between glucose utilization and excitatory amino acid activity suggests that IGF-1 may act on specific neural pathways to increase glutamate activity in brain regions associated with learning and memory.

Research studies clearly indicate that age-related changes in cellular and tissue function are linked to decreases in the anabolic hormones, growth hormone and insulin-like growth factor (IGF)-1. Although there has been extensive research on the effects of these hormones on bone and muscle mass, their effect on cerebrovascular and brain ageing has received little attention. We have also observed that in response to moderate calorie restriction (a treatment that increases mean and maximal lifespan by 30-40%), age-related decreases in growth hormone secretion are ameliorated (despite a decline in plasma levels of IGF-1) suggesting that some of the effects of calorie restriction are mediated by modifying the regulation of the growth hormone/IGF-1 axis. Recently, we have observed that microvascular density on the surface of the brain decreases with age and that these vascular changes are ameliorated by moderate calorie restriction. Analysis of cerebral blood flow paralleled the changes in vasculature in both groups. Administration of growth hormone for 28 d was also found to increase microvascular density in aged animals and further analysis indicated that the cerebral vasculature is an important paracrine source of IGF-1 for the brain. In subsequent studies, administration of GHRH (to increase endogenous release of growth hormone) or direct administration of IGF-I was shown to reverse the age-related decline in spatial working and reference memory. Similarly, antagonism of IGF-1 action in the brains of young animals impaired both learning and reference memory. Investigation of the mechanisms of action of IGF-1 suggested that this hormone regulates age-related alterations in NMDA receptor subtypes (e.g. NMDAR2A and R2B). The beneficial role of growth hormone and IGF-1 in ameliorating vascular and brain ageing are counterbalanced by their well-recognised roles in age-related pathogenesis. Although research in this area is still evolving, our results suggest that decreases in growth hormone and IGF-1 with age have both beneficial and deleterious effects. Furthermore, part of the actions of moderate calorie restriction on tissue function and lifespan may be mediated through alterations in the growth hormone/IGF-1 axis.

Moderate caloric restriction (60% of ad libitum intake) is an important model to investigate potential mechanisms of biological aging. This regimen has been reported to decrease the number of pathologies and increase life span in all species tested to date. Although moderate caloric restriction induces a wide range of physiological changes within the organism, adaptive changes within the endocrine system are evident and serve to maintain blood levels of glucose. These alterations include an increase in growth hormone secretory dynamics and a decline in plasma levels of IGF-1. These endocrine compensatory mechanisms can be induced at any age, and we have proposed that these alterations mediate some of the beneficial aspects of moderate caloric restriction. Numerous studies indicate that growth hormone and IGF-1 decrease with age and that administration of these hormones ameliorates the deterioration of tissue function evident in aged ad libitum-fed animals, suggesting that the absence of these hormones contributes to the phenotype of aging. Nevertheless, IGF-1 is an important risk factor in age-related pathologies including lung, breast, and prostate cancer. From these studies, we propose that endocrine compensatory mechanisms induced by moderate caloric restriction (including increased growth hormone and decreased IGF-1) decrease the stimulus for cellular replication, resulting in a decline in pathologies and increased life span observed in these animals. These findings have important implications for potential mechanisms of moderate caloric restriction and suggest that neuroendocrine compensatory mechanisms exert a key role on the actions of moderate caloric restriction on life span.

Numerous studies have been conducted examining nitrate (NO 3 ) leaching losses from agricultural land. Simulation models have been developed that allow one to predict the potential of NO 3 to leach to groundwater. However, many of these models treat NO 3 as a conservative tracer and do not evaluate surface chemistry. This study evaluated the surface charge properties and NO 3 adsorption capacity of four acid southeastern subsoils. Significant anion exchange capacity and NO 3 retention was found for two of the soils. Point of zero net charge (PZNC) was determined using an ion exchange method. Values of 3.1 and 3.6 were determined for two of the soils while PZNC values were not quantifiable for the other two soils in the pH range of 3 to 7. Nitrate adsorption isotherms were measured on untreated and chloride-saturated soils. Nitrate adsorption maxima determined from the linearized form of the Langmuir equation ranged from 1.40 to 2.13 cmol c kg -1 . Coefficients of determination (R 2 ) and adsorption maxima increased after chloride saturation. This was attributed to competition from anions such as sulfate, fluoride, and phosphate. Net positive charge and NO 3 retention were found to depend on the type and quantity of both variable and permanent charged minerals present in the soil and the composition of the exchange complex. These results demonstrated that acid subsoils high in variable charge minerals may have the potential to retard NO 3 movement to groundwater. Therefore, simulation models may need to account for NO 3 adsorption when modeling NO 3 movement in acid soils dominated by variable charge minerals.

Objective: The purpose of this manuscript is to review the literature concerning the alterations in the microvasculature in experimental hypertension and aging. We also present new unpublished data and results where previous studies have not addressed important questions. Methods: The new studies were performed using a chronic cranial window to allow multiple observations of the cortical surface vasculature over time. In vivo video, microscopic techniques were used to study long-term changes in microvascular caliber (vasomotion). In some studies, a chronic, in-dwelling aortic catheter allowed chaotic analysis of short-term blood pressure and heart rate variations. Results: In these new studies we demonstrated a reduction in number of small arteriolar endpoints per cortical surface area in the spontaneously hypertensive rat and in the old Brown-Norway rat. There was also a reduction in the number of arteriole-to-arteriole anastomotic connections in the older rat. These vascular changes in the old rat were revised or prevented by caloric restriction. In the old rat, there was also a reduction in the variability of blood pressure, heart rate and microvessel caliber (vasomotion). Conclusions: These studies suggest that there is an alteration in the morphology of the small arterioles in hypertension and aging, that may lead to reduced ability to perfuse cortical tissue. In addition, there appears to be a diminution of overall short-term cardiovascular and microvascular control.

Intrinsic rhythmic changes in the diameter of pial cerebral arterioles (30-70 microns) in anesthetized normotensive and hypertensive rats were assessed in vivo to determine if any significant differences exist between the two strains. All diameter measurements were analyzed using a traditional graphic analysis technique and a new frequency spectrum analysis technique known as the Prony Spectral Line Estimator. Graphic analysis of the data revealed that spontaneously hypertensive rats (SHR) possess a significantly greater fundamental frequency (5.57 +/- 0.28 cycles/min) of vasomotion compared to the control Wistar-Kyoto normotensive rats (WKY) (1.95 +/- 0.37 cycles/min). Furthermore, the SHR cerebral arterioles exhibited a significantly greater amplitude of vasomotion (10.07 +/- 0.70 microns) when compared to the WKY cerebral arterioles of the same diameter (8.10 +/- 0.70 microns). Diameter measurements processed with the Prony technique revealed that the fundamental frequency of vasomotion in SHR cerebral arterioles (6.14 +/- 0.39 cycles/min) was also significantly greater than that of the WKY cerebral arterioles (2.99 +/- 0.42 cycles/min). The mean amplitudes of vasomotion in the SHR and WKY strains obtained by the Prony analysis were found not to be statistically significant in contrast to the graphic analysis of the vasomotion amplitude of the arterioles. In addition, the Prony system was able to consistently uncover a very low frequency of vasomotion in both strains of rats that was typically less than 1 cycle/min and was not significantly different between the two strains. The amplitude of this slow frequency was also not significantly different between the two strains. The amplitude of the slow frequency of vasomotion (less than 1 cycle/min) was not different from the amplitude of the higher frequency (2-6 cycles/min) vasomotion by Prony or graphic analysis. These data suggest that a fundamental intrinsic defect exists in the spontaneously hypertensive rat that may contribute to the pathogenesis of hypertension in these animals.

The dentate gyrus of the hippocampus is one of few regions in the adult mammalian brain characterized by ongoing neurogenesis. Significantly, recent studies indicate that the rate of neurogenesis in the hippocampus declines with age, perhaps contributing to age-related cognitive changes. Although a variety of factors may influence the addition of new neurons in the adult dentate gyrus, the mechanisms responsible for the age-related reduction remain to be established. Insulin-like growth factor-I (IGF-I) is one promising candidate to regulate neurogenesis in the adult and aging brain since it influences neuronal production during development and since, like the rate of neurogenesis, it decreases with age. In the current study, we used bromodeoxyuridine labeling and multilabel immunofluorescence to assess age-related changes in neuronal production in the dentate gyrus of adult Brown Norway x Fischer 344 rats. In addition, we investigated the relationship between changes in neurogenesis and the age-dependent reduction in IGF-I by evaluating the effect of i.c.v. infusion of IGF-I on neurogenesis in the senescent dentate gyrus. The analyses revealed an age-dependent reduction in the number of newly generated cells in the adult dentate subgranular proliferative zone and, in addition, a 60% reduction in the differentiation of newborn cells into neurons. Restoration of IGF-I levels in senescent rats significantly restored neurogenesis through an approximately three-fold increase in neuronal production. The results of this study suggest that IGF-I may be an important regulator of neurogenesis in the adult and aging hippocampus and that an age-related decline in IGF-I-dependent neurogenesis could contribute to age-related cognitive changes.

In this study, we examined the effects of age and growth hormone replacement on both coronary blood flow and capillary density. Blood flow was measured by using [(14)C]-iodoantipyrine in three groups of anesthetized Brown Norway x Fischer 344 rats: young vehicle-treated animals (6 months; n = 13), old vehicle treated animals (30 months; n = 9), and old animals treated with bovine growth hormone (200 microg/kg) twice a day for 30 days (30 months; n = 7). Capillary density was measured by color segmentation analysis of sections stained for platelet endothelial cell adhesion molecule-1. In all regions examined, coronary blood flow decreased with age, and growth hormone administration resulted in an increase in flow compared to vehicle-treated animals. Capillary density decreased with age in the apex and the left ventricular middle segment. In response to growth hormone administration, capillary density increased significantly in the apex but not in other regions of the heart. Our results demonstrate that growth hormone enhances regional myocardial blood flow in the aged heart and suggest that part of this effect could be due to an increase in capillary density.

The present study was designed to assess the impact of moderate caloric restriction (60% of ad libitum fed animals) on cerebral vascular density and local cerebral blood flow. Vascular density was assessed in male Brown–Norway rats from 7–35 months of age using a cranial window technique. Arteriolar density, arteriole-arteriole anastomoses, and venular density decreased with age and these effects were attenuated by moderate caloric restriction. Analysis of local cerebral blood using [14C]iodoantipyrine indicated that basal blood flow decreased with age in CA1, CA3 and dentate gyrus of hippocampus; similar trends were evident in cingulate, retrosplenal, and motor cortex. Basal blood flow was increased in all brain regions of moderate caloric restricted old animals (compared to old ad libitum fed animals) and no differences were observed between ad libitum fed young and caloric restricted older animals. In response to a CO2 challenge to maximally dilate vessels, blood flow increased in young and old ad libitum fed animals, but a similar increase was not observed in caloric restricted old animals. We conclude that a decrease in cerebral vasculature is an important contributing factor in the reduction in blood flow with age. Nevertheless, vessels from young and old animals have the capacity to dilate in response to a CO2 challenge and, after CO2, no differences are observed between the two age-groups. These results are consistent with the hypothesis that aged animals fail to adequately regulate local cerebral blood flow in response to physiological stimuli. Moderate caloric restriction increases microvascular density and cerebral blood flow in aged animals but tissues exhibit little or no increase in blood flow in response to CO2 challenge. The cause of this deficient response may indicate that vessels are maximally dilated in aged calorically restricted animals or that they fail to exhibit normal regulatory control.

Ageing in mammals is characterized by a decline in plasma levels of insulin-like growth factor-1 that appears to contribute to both structural and functional changes in a number of tissues. Although insulin-like growth factor-1 has been shown to provide trophic support for neurons and administration of insulin-like growth factor-1 to ageing animals reverses some aspects of brain ageing, age-related changes in insulin-like growth factor-1 or type 1 insulin-like growth factor receptors in brain have not been well documented. In this series of studies, insulin-like growth factor-1 messenger RNA and protein concentrations, and type 1 insulin-like growth factor receptor levels were analysed in young (three to four- and 10-12-month-old), middle-aged (19-20-month-old) and old (29-32-month-old) Fisher 344 x Brown Norway rats. Localization of insulin-like growth factor-1 messenger RNA throughout the lifespan revealed that expression was greatest in arteries, arterioles, and arteriolar anastomoses with greater than 80% of these vessels producing insulin-like growth factor-1 messenger RNA. High levels of expression were also noted in the meninges. No age-related changes were detected by either in situ hybridization or quantitative dot blot analysis of cortical tissue. However, analysis of insulin-like growth factor-1 protein levels in cortex analysed after saline perfusion indicated a 36.5% decrease between 11 and 32 months-of-age (P

Previous studies have reported changes in insulin-like growth factor I (IGF-I) mRNA expression during early postnatal development of the rat brain. Although changes in IGF-I gene expression have been documented in a wide range of central nervous system structures during early development and investigated in the hippocampus during aging, no study has compared changes in IGF-I gene expression in different brain regions across the life span. The present study assessed the distribution of IGF-I gene expression using in situ hybridization in rats aged 2-30 months. Dot blots were used as a quantitative assessment of cortical IGF-I mRNA. Results indicate that both the distribution and levels of brain IGF-I mRNA do not change significantly between 2 and 30 months of age in the rat. However, in spite of relatively constant levels of mRNA, other studies from our laboratory have demonstrated that cortical IGF-I protein levels decrease 36.6% between 11 and 32 months of age, suggesting that IGF-I function is decreased with increasing age.

Several reports have demonstrated that cerebral blood flow decreases with age and may contribute to neurodegenerative changes found in aging animals and man. Because GH and insulin-like growth factor 1 (IGF-1) decrease with age and have an important role in vascular maintenance and remodeling, we hypothesized that the decrease in cerebral blood flow is associated with a rarefaction of cerebral blood vessels resulting from a decline in GH and IGF-1. Measurements of vascular density (number of vessels/cortical surface area) in both Brown-Norway and Fisher 344/Brown-Norway rats were made at 5, 13, and 29 months of age using chronic cranial window chambers that allowed viewing of the cortical surface and its corresponding vasculature. Correlations were made with plasma levels of IGF-1. In Brown-Norway rats, arteriolar density decreased from 15.53 +/- 1.08 to 9.49 +/- 0.62 endpoints/mm2 in 7- and 29-month-old animals, respectively (P < 0.05). A decline was observed also in arteriolar anastomoses [3.05 +/- 0.21 to 1.42 +/- 0.24 connections/mm2 in 7- and 29-month-old animals (P < 0.05)]. Venular density did not decrease with age. Similar changes were observed in Fisher 344/Brown-Norway rats. The number of cortical surface arterioles was correlated with plasma IGF-1 levels at the time of vascular mapping (r = 0.772, P < 0.05), and injection of bovine GH (0.25 mg/kg, s.c., twice daily for 35 days) to 30-month-old animals increased both plasma IGF-1 and the number of cortical arterioles. These data indicate that: 1) vascular density on the surface of the cortex decreases with age; 2) vascular density is correlated with plasma levels of IGF-1; and 3) injection of GH increases cortical vascular density in older animals. We conclude that GH and IGF-1 have an important role in the decline in vascular density with age and suggest that decreases in vascular density may have important implications for the age-related decline in cerebral blood flow and brain function.

This study was undertaken to explore the time course of the metabolic response to isohemic blood volume expansion (30%) in normotensive, unanesthetized Sprague-Dawley rats. Whole blood, drawn from a femoral artery catheter of conscious donor rats, was infused into the jugular vein of recipient rats. Blood samples were drawn from a carotid artery of recipient rats at time points beginning immediately post-volume expansion (IPVE) up through 5 days post-volume expansion (PVE). To characterize the attendant compensatory mechanisms, the plasma concentrations of electrolytes and fluid regulatory hormones were determined. Hematocrit began to raise IPVE and was significantly elevated above control IPVE 20, 30, 40, 60, and 90 min, and 2, 4, 6, 8, 12, and 24 hr PVE. Consistent with our current understanding of the hormonal response to excess volume, atrial natriuretic factor was significantly increased above the prevolume expansion (control) values 0-30 min PVE. Surprisingly, plasma aldosterone levels were significantly increased above control at 20 and 30 min and 6 hr PVE, whereas plasma renin activity was significantly decreased 30-40 min PVE. Plasma sodium was not changed from control values except for a significant increase at 6 hr post-volume expansion. Plasma potassium, osmolality, and arginine vasopressin levels were not altered by the volume expansion. These studies delineate the physiologic time scheme operative in the regulation of fluid volume during acute ischemic volume expansion.

This chapter will present the advantages and disadvantages of chronic in vivo preparations and describe the state of the art for some of these preparations. Investigations employing chronic in vivo techniques offer many advantages. For example, tumor necrosis factor alpha (TNFα) has been shown to inhibit the proliferation of endothelial cells in vitro, and to stimulate angiogenesis in vivo.1 The investigation of the interaction of all physiological systems is not possible with in vitro techniques. On the other hand, it is difficult to isolate individual systems and study precise mechanisms of action in vivo. Extrapolation of results acquired from in vivo studies to human medicine is also more appropriate. Knowing the in vivo effects of pharmacological interventions or physiological disturbances on undisturbed microvascular beds is a definite benefit to the interpretation of the true effect of the agent. Ideally, we need to know the response of all vascular beds to a particular perturbation. However, windows into the internal vascular beds (such as refinement of these techniques. Rapid progress is being made in telemetry methods for continuous monitoring of hemodynamic variables. Advancements in this area will also spill over into the telemetering of microvascular images.

The chronic cranial window preparation allows repeated measurements of the same pial vessels in unanesthetized rats for several weeks and correlation with 24-h monitoring of hemodynamic variables. Nimodipine (20 mg) or placebo was given via two subcutaneous pellets. Large arterioles dilated 26 and 16%, at hour 1 and days 6-13, respectively (P less than 0.02). There was an increase in number of small arterioles throughout the whole observation period with the maximal increment of 47% (P less than 0.05) at days 6-13. Maximal vasodilation with 10% CO2 indicated that the increase in number of small arterioles after administering nimodipine was not caused by the opening of previously closed vessels. The total length of small arterioles and venules increased 47 and 23% at days 6-13, respectively (P less than 0.001). These increases seem to be caused by the increases in the numbers of vessels, because the average length of the small vessels did not appear to change. This suggests that nimodipine reduces cerebral vascular resistance by causing cerebral microvessel neovascularization. Our data demonstrate that the administration of nimodipine (20 mg) is potent in dilating pial arterioles in the short-term without affecting systemic arterial pressure, and that its long-term effect results in new vessel growth.

Previous studies in rats have demonstrated that immune system dysfunction contributes to the aetiology of spontaneous hypertension. Chronic immunosuppression with cyclophosphamide attenuated the level of hypertension in Okamoto spontaneously hypertensive rats (SHR) by approximately 50%. Also, neonatal thymic implants delayed the development of spontaneous hypertension and significantly attenuated its level at the age of 22 weeks in SHR. In the present study, the effect of thymectomy at the age of 4 weeks on blood pressure was investigated in SHR and Wistar-Kyoto (WKY) rats. The removal of the thymus gland in 4-week-old SHR produced a significant reduction in systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) when rats were 16-19 weeks old, while no pressure reduction was observed in WKY rats. The decrease in arterial pressure of 16-week-old SHR was associated with a significant reduction in lymphocyte count at this age as compared with the control group. In 1-year-old SHR, thymectomized at the age of 4 weeks, there was no significant difference in arterial pressure or lymphocyte count compared with controls. These data support the hypothesis that an immune imbalance may be important in the development of spontaneous hypertension. We conclude that thymectomy at a young age (4 weeks) delays the development of hypertension in SHR.

Chronic microcirculatory alterations produced by prolonged use of a vasoactive drug were repeatedly observed in the same skeletal muscle vessels of the dorsal microcirculatory chamber. Arterioles and venules with diameters averaging from 70 to 90 microns, the size range contributing most to peripheral vascular resistance, were measured daily for 6 days to determine differences in diameter, tortuosity, and number of branches. Hydralazine was given as a subcutaneous pellet (2.5 mg), with a release life of 21 days. Hydralazine caused a 39% dilation in arterioles of Wistar-Kyoto rats (WKY) at 3 hours but only an 8% dilation in those of spontaneously hypertensive rats (SHR). At 6 hours, arterioles in both groups were similarly dilated (30-33%). Beyond 6 hours, both SHR and WKY arterioles returned to their prehydralazine control diameter, even though arterial pressure was still reduced. By Day 6, in WKY, but not SHR, there was an increase in the tortuosity of arterioles and a tendency for an increase in their number. Venous diameter was also increased on Day 6, consistent with the fluid retention effect of hydralazine. These data indicate that some so-called vasodilators may cause long-term alterations in growth of vessels rather than an increase in vessel caliber.

The investigation of cardiovascular function necessarily involves a consideration of the exchange of substances at the capillary. If cardiovascular function is compromised or in any way altered during exposure to zero gravity in space, then it stands to reason that microvascular function is also modified. We have shown that an increase in cardiac output similar to that reported during simulated weightlessness is associated with a doubling of the number of post-capillary venules and a reduction in the number of arterioles by 35%. If the weightlessness of space travel produces similar changes in cardiopulmonary volume and cardiac output, a reasonable expectation is that astronauts will undergo venous neovascularization. We have developed an animal model in which to correlate microvascular and systemic cardiovascular function. The microcirculatory preparation consists of a lightweight, thermo-neutral chamber implanted around intact skeletal muscle on the back of a rat. Using this technique, the performed microvasculature of the cutaneous maximus muscle may be observed in the conscious, unanesthetized animal. Microcirculatory variables which may be obtained include venular and arteriolar numbers, lengths and diameters, single vessel flow velocities, vasomotion, capillary hematocrit anastomoses and orders of branching. Systemic hemodynamic monitoring of cardiac output by electromagnetic flowmetry, and arterial and venous pressures allows correlation of macro- and microcirculatory changes at the same time, in the same animal. Observed and calculated hemodynamic variables also include pulse pressure, heart rate, stroke volume, total peripheral resistance, aortic compliance, minute work, peak aortic flow velocity and systolic time interval. In this manner, an integrated assessment of total cardiovascular function may be obtained in the same animal without the complicating influence of anesthetics.

Adenosine is a well-known locally active vasodilator metabolite. A major role in blood flow regulation has been ascribed to adenosine. This investigation compared the dose-response curves to adenosine in the cremaster of spontaneously hypertensive rats (SHRs) with Wistar-Kyoto rats (WKYs) at an age when cardiac output and blood flow of the SHR have been shown to be increased (6 weeks). Each concentration (10(-5), 10(-4), and 10(-3) M) was injected retrograde through the femoral artery as a bolus of 100 microliters/sec and 300 microliters/3 sec. Changes in arteriolar diameter were recorded for 3 min. Continuous monitoring techniques enabled detection of differences between strains using an average of the 3-min response (DAVG) and the 3-min response pattern. In contrast, no interstrain differences were observed using the peak diameter response (DMAX). SHRs exhibited a reduced sensitivity to adenosine which was apparent in the dose-response curves based on DAVG with 3-sec injections (P less than 0.02). There was no difference with 1-sec injections. Analysis of the 3-min response pattern showed that SHRs also returned to control diameters faster than WKYs, except at the highest dose when vessels of both strains remained dilated. These results are consistent with the role of metabolic (vasodilator) autoregulation in hypertension. If extracellular adenosine is washed out in the SHR, intraarterial injections of the same concentration of adenosine would cause a reduced response in SHRs.