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31.
R H Verhaeghe R R Lorenze M A McGrath J T Shepherd P M Vanhoutte 《Federation proceedings》1978,37(2):208-211
Evidence has accumulated that several factors, which have been proposed as mediators of exercise hyperemia, can modulate adrenergic neurotransmission in blood vessels. Adenosine and the adenine nucleotides depress the response of isolated blood vessels of the dog to nerve stimulation more than that to exogenous norepinephrine; this difference is explained by a decreased release of the neurotransmitter. Potassium, hyperosmolarity, and acidosis also depress adrenergic neurotransmission in isolated veins. These results are consistent with the hypothesis that metabolic changes in the vicinity of the adrenergic neuroeffector junction are capable of decreasing the output of neurotransmitter to the blood vessels in the exercising muscle. 相似文献
32.
An experimental comparison of intracellular ice formation and freeze-thaw survival of hela S-3 cells 总被引:2,自引:0,他引:2
A small-volume fluorescent dye viability assay has been successfully applied to a conduction cryomicroscope freezing-thawing stage as a means of determining post-thaw survival of the nucleated mammalian cell HeLa S-3. The survival signature for HeLa S-3 cells has been determined, revealing an optimum cooling rate of −30 °C/min where the maximum survival is 30%. No cells survive for cooling rates greater than −128 °C/min and the decreased survival at supraoptimal cooling rates coincides with a linear increase in the percentage of cells containing intracellular ice from 0% at −16 °C/min to 100% at −128 °C/min.Although no data were taken to identify increased salt concentration as the mechanism responsible for cell injury at suboptimal cooling rates, the post-thaw leakage of intracellular fluorescent dye at these rates takes approximately 4–10 min as opposed to instantaneous release of dye for cells which contain ice at the high cooling rates. This indicates two modes of damage.Cell number density has been identified as an important parameter in freezing studies since survival can be enhanced at slow rates by packing cells together in groups. Packing also causes a greater fraction of the cells in a sample to have intracellular ice present, thus decreasing survival at the faster rates. These responses can be explained by assuming that the outer cells in a group protect the inner ones from solution damage at slow rates, yet restrict water flux from the inner cells at faster rates, causing an increased likelihood of intracellular ice formation. Both of these results are consistent with the dual-mechanism freezing damage theory proposed by Mazur. 相似文献
33.
J J McGrath B Ostádal J Procházka M Wachtlova V Rychterova 《Journal of applied physiology》1975,39(2):205-208
Resistance to isoproterenol-induced cardiac necrosis (IPRO) was compared in rats exposed to two types of hypoxia (i.e., hypobaric and anemic). IPRO was induced by two consecutive, subcutaneous injections of isoproterenol (80 mg/kg) at 24-h intervals. The animals were killed on the third day and the severity of the lesion was evaluated on a 0 (no damage) to 4 (severely damaged) scale. White male rats (HA) were exposed in a barometric chamber to a simulated altitude of 7,000 m (307 mmHg) for 4 h/day for 24 days. Two groups of control rats were kept at sea level; one group (SLA) was the same age and one group (SLW) was the same weight as the altitude-exposed rats. The HA rats were significantly more resistant to IPRO with a mean necrogenic rating of 1.8 compared to 3.3 for the SLA and SLW rats. Infant rats (AA) were made anemic by feeding full-cream milk and glucose for 100 days after weaning. Two groups of control animals were fed a standard laboratory diet; one group (AC) was the same age and one group (AW) was the same weight as the AA rats. There was no significant difference in the necrogenic ratings of the AA (3.3), AC (3.5), or WC (3.7) hearts. Thus, hypobaric hypoxia affords some protection against IPRO which is not afforded by anemic hypoxia. Similarities and differences in the two hypoxias are discussed. 相似文献
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Alice Toso Simona Schifano Charlotte Oxborough Krista McGrath Luke Spindler Anabela Castro Lucy Evangelista Vanessa Filipe Maria José Gonçalves Antonio Marques Inês Mendes da Silva Raquel Santos Maria João Valente Iona McCleery Michelle Alexander 《American journal of physical anthropology》2021,176(2):208-222
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Sharon A. Appleyard Safia Maher John J. Pogonoski Stephen J. Bent Xin-Yi Chua Annette McGrath 《Journal of fish biology》2021,98(5):1421-1432
Natural history collections are repositories of biodiversity and are potentially used by molecular ecologists for comparative taxonomic, phylogenetic, biogeographic and forensic purposes. Specimens in fish collections are preserved using a combination of methods with many fixed in formalin and then preserved in ethanol for long-term storage. Formalin fixation damages DNA, thereby limiting genetic analyses. In this study, the authors compared the DNA barcoding and identification success for frozen and formalin-fixed tissues obtained from specimens in the CSIRO Australian National Fish Collection. They studied 230 samples from fishes (consisting of >160 fish species). An optimized formalin-fixed, paraffin-embedded DNA extraction method resulted in usable DNA from degraded tissues. Four mini barcoding assays of the mitochondrial DNA (mtDNA) were characterized with Sanger and Illumina amplicon sequencing. In the good quality DNA (without exposure to formalin), up to 88% of the specimens were correctly matched at the species level using the cytochrome oxidase subunit 1 (COI) mini barcodes, whereas up to 58% of the specimens exposed to formalin for less than 8 weeks were correctly identified to species. In contrast, 16S primers provided higher amplification success with formalin-exposed tissues, although the COI gene was more successful for identification. Importantly, the authors found that DNA of a certain size and quality can be amplified and sequenced despite exposure to formalin, and Illumina sequencing provided them with greater power of resolution for taxa identification even when there was little DNA present. Overall, within parameter constraints, this study highlights the possibilities of recovering DNA barcodes for identification from formalin-fixed fish specimens, and the authors provide guidelines for when successful identification could be expected. 相似文献
39.
The liver plays a central role in regulating lipid metabolism and facilitates efficient lipid utilization and storage. We discovered that a modest increase in maternal dietary fat in mice programs triglyceride storage in the liver of their developing offspring. The activation of this programming is not apparent, however, until several months later at the adult stage. We found that the perinatal programming of adult hepatic triglyceride storage was controlled by the eIF2α kinase GCN2 (EIF2AK4) in the brain of the offspring, which stimulates epigenetic modification of the Pparγ2 gene in the neonatal liver. Genetic ablation of Gcn2 in the offspring exhibited reduced hepatic triglyceride storage and repressed expression of the peroxisome proliferator-activated receptor gamma 2 (Pparγ2) and two lipid droplet protein genes, Fsp27 and Cidea. Brain-specific, but not liver-specific, Gcn2 KO mice exhibit these same defects demonstrating that GCN2 in the developing brain programs hepatic triglyceride storage. GCN2 and nutrition-dependent programming of Pparγ2 is correlated with trimethylation of lysine 4 of histone 3 (H3K4me3) in the Pparγ2 promoter region during neonatal development. In addition to regulating hepatic triglyceride in response to modest changes in dietary fat, Gcn2 deficiency profoundly impacts the severity of the obese-diabetic phenotype of the leptin receptor mutant (db/db) mouse, by reducing hepatic steatosis and obesity but exacerbating the diabetic phenotype. We suggest that GCN2-dependent perinatal programming of hepatic triglyceride storage is an adaptation to couple early nutrition to anticipated needs for hepatic triglyceride storage in adults. However, increasing the hepatic triglyceride set point during perinatal development may predispose individuals to hepatosteatosis, while reducing circulating fatty acid levels that promote insulin resistance. 相似文献
40.
The Impact of Adult Vitamin D Deficiency on Behaviour and Brain Function in Male Sprague-Dawley Rats
Jacqueline H. Byrne Meggie Voogt Karly M. Turner Darryl W. Eyles John J. McGrath Thomas H. J. Burne 《PloS one》2013,8(8)