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Query: UMLS:C0848237 (acute stress)
 4,619 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of dietary Na+, K+, and Cl- and of acute stress on plasma levels of Na+, K+, aldosterone, and corticosterone were evaluated in vivo in birds. The dietary effects were studied in growing White Rock chicks, whereas the larger turkey was preferred for the acute stress study. Although plasma corticosterone remained unaffected, plasma aldosterone concentration decreased with increasing levels of dietary Na+ reaching a minimum at a dietary level of 72 meq/kg. Plasma Na+ remained unchanged when dietary Na+ levels increased up to 72 meq/kg but then rose with increasing Na+ intake. Plasma K+ was slightly depressed by high levels of dietary Na+ and increased by dietary K+. Neither plasma Na+ nor circulating adrenal hormones were affected by dietary K+ or dietary Cl-. Acute stress stimulated both aldosterone and corticosterone without any effect on the levels of the plasma minerals. The results suggest that of the two main corticoids, only aldosterone responds to dietary Na+ in chicks. This is in contrast to the indiscriminate stimulation of both hormones by stress, indicating different pathways of stimulation. The results also suggest that aldosterone is involved in the regulation of plasma Na+ only at low intakes of Na+ and that dietary K+ and Cl- are not involved in the aldosterone-Na+ feedback relationship.
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PMID:Concentration of adrenocortical hormones in relation to cation homeostasis in birds. 360 85

We designed an experiment to study the role of light history and polyunsaturated fatty acids (PUFA) on the susceptibility of the albino rat retina to light damage. Albino rats were born to dams that had been kept in either 1 lx or 250 lx cyclic light for 0-4 days prior to delivery and fed one of three diets containing either 10% (by weight) hydrogenated coconut oil (COC, no n-3 nor n-6 fatty acids), safflower oil (SAF, high n-6, < 0.1% n-3 fatty acids), or linseed oil (LIN, high n-3, low n-6 fatty acids). After weaning, the rats were maintained in the same light environment and fed the same diets for 9 weeks, at which time some were killed and their retinas processed for morphometric analysis. Animals raised in bright cyclic light had shorter ROS lengths and thinner outer nuclear layers (ONL) than rats raised in dim cyclic light. The LIN animals had a thinner ONL than animals of the SAF or COC groups. Rats from each diet and light rearing groups were exposed to constant illumination of 2000 lx for 24 hr, after which they and non-exposed controls were placed in 1 lx cyclic light for 10 days and analysed for changes in ONL thickness. In the 250 lx (bright; B) groups, there was no effect of acute light stress on ONL thickness, although both control and stressed LIN animals had a thinner ONL than the corresponding COC and SAF groups. However, in the rats raised in 1 lx cyclic light, acute stress resulted in significant retinal damage (i.e. decrease in ONL thickness) in the three diet groups combined. The superior region was damaged the most and the severity was dependent on diet, as evidenced by the LIN group having a greater reduction in ONL thickness than the SAF group after light stress. From these results we conclude that rats on diets high in n-3 fatty acids are more susceptible to photoreceptor cell loss than animals fed n-6 or no polyunsaturated fatty acids when raised in dim cyclic light. These results show that both diet and light history play a role in the susceptibility of the retina to acute and chronic effects of light and suggest a role for lipid peroxidation in retinal light damage.
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PMID:Effect of dietary fat on the response of the rat retina to chronic and acute light stress. 778 10

In case new diagnostic procedures for Alzheimer's dementia (AD) appear, Nuclear Medicine (NM) would like to be aware of them in order to evaluate its own contribution to diagnose AD by SPET and PET brain studies. Recently, sleep disturbances were studied in AD and tend to be diagnostic for early AD. In AD the actual time of night sleep was found to be 5.7 h, while awakeness time for the same night sleep increased to 2.7 h. Also in AD, the REM and the slow wave stage (SWS) during sleep are shorter and hypopnea and apnea phases are abundant. Internal body temperature during night sleep is only slightly increased in AD, while in temporofrontal dementia and in normal individuals this increase is significant. The circadian rhythm of melatonin is disturbed in AD. The normal duration of inspiration and expiration during daytime which is reversed during normal night sleep, has not been studied in patients with AD. However, this reverse condition favoring inspiration is expected to provide more oxygen to the brain. Chronic but not acute stress causes memory loss and is currently being studied by us as a possible causative factor for memory loss in AD. Tomographic SPET and PET brain studies can locate the site of brain damage in AD. This is important since memory has recently been classified into four categories, namely episodic, semantic, procedural and working memory. In early AD only procedural memory remains intact. This means that these patients may drive a car, do computer word processing and play some games at home or/and in the field. This memory is located in specific nuclei in the cerebellum and the occipital frontal area which do not relate to sites of other kinds of memory. This difference could be well identified by tomographic SPET or PET studies. Thus NM may also diagnose the early stage of AD. Another issue refers to the indications that the unified Medicare and Medicaid system in the USA has issued on September 15, 2004 for performing a PET (18)F-FDG study for AD. These indications are fully described in this editorial.
Hell J Nucl Med
PMID:[Alzheimer's dementia, sleep disorders and nuclear medicine]. 1588 44

The modulatory action of beta-adrenergic and opioidergic pathways on the cortisol response to acute stressors was investigated using gonadectomized male miniature pigs. Three types of stressors, nose-snare (NS, for 2 min. each on four occasions at 30 min. intervals); high intensity cracker blasts (CB, two blasts at 3 min intervals) and ACTH (1 i.u./kg BW, i.v.) were utilized 80 min after start of blood sampling. For assessment of cortisol blood samples were withdrawn every 20 min for 200 min. In addition, animals received i.v. injections of either isoproterenol (5 microg/ kg) or propranolol (0.5 mg/kg) or naloxone (1 mg/kg) 15 or 30 min before the application of stressor. Stress of repeated NS application as well as ACTH treatment, resulted in immediate secretion of cortisol (p<0.001). Blast of crackers resulted in a transient increase in cortisol (p<0.05). Isoproterenol stimulated the basal cortisol secretion for about 20 min in unstressed pigs (p <0.01) but propranolol had no effects. Isoproterenol also reinforced (p<0.05) the effect of CB, but had no effect on the cortisol response to nose-snare. In contrast, response to NS was reduced (p=0.02) by propranolol. Neither isoproterenol nor propranolol altered the cortisol response to ACTH application. Pretreatment with naloxone significantly increased the cortisol response to NS (p<0.01) and to CB (p<0.01), but had no effects on ACTH-induced cortisol release. In conclusion, the beta-adrenergic involvement is evident in the cortisol response to acute stress of nose-snare. Furthermore, the results indicate that activation of endogenous opioid system during stress mitigates adrenal response.
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PMID:Beta-adrenergic and opioidergic modulation of cortisol secretion in response to acute stress. 1770 79

Leaf, bark, xylem and root tissues were used to make nine cDNA libraries from non-stressed (control) 'Royal Gala' apple trees, and from 'Royal Gala' trees exposed to either low temperature (5 degrees C for 24 h) or water deficit (45% of saturated pot mass for 2 weeks). Over 22 600 clones from the nine libraries were subjected to 5' single-pass sequencing, clustered and annotated using blastx. The number of clusters in the libraries ranged from 170 to 1430. Regarding annotation of the sequences, blastx analysis indicated that within the libraries 65-72% of the clones had a high similarity to known function genes, 6-15% had no functional assignment and 15-26% were completely novel. The expressed sequence tags were combined into three classes (control, low-temperature and water deficit) and the annotated genes in each class were placed into 1 of 10 different functional categories. The percentage of genes falling into each category was then calculated. This analysis indicated a distinct downregulation of genes involved in general metabolism and photosynthesis, while a significant increase in defense/stress-related genes, protein metabolism and energy was observed. In particular, there was a three-fold increase in the number of stress genes observed in the water deficit libraries indicating a major shift in gene expression in response to a chronic stress. The number of stress genes in response to low temperature, although elevated, was much less than the water deficit libraries perhaps reflecting the shorter (24 h) exposure to stress. Genes with greater than five clones in any specific library were identified and, based on the number of clones obtained, the fold increase or decrease in expression in the libraries was calculated and verified by semiquantitative polymerase chain reaction. Genes, of particular note, that code for the following proteins were overexpressed in the low-temperature libraries: dehydrin and metallothionein-like proteins, ubiquitin proteins, a dormancy-associated protein, a plasma membrane intrinsic protein and an RNA-binding protein. Genes that were upregulated in the water deficit libraries fell mainly into the functional categories of stress (heat shock proteins, dehydrins) and photosynthesis. With few exceptions, the overall differences in downregulated genes were nominal compared with differences in upregulated genes. The results of this apple study are similar to other global studies of plant response to stress but offer a more detailed analysis of specific tissue response (bark vs xylem vs leaf vs root) and a comparison between an acute stress (24-h exposure to low temperature) and a chronic stress (2 weeks of water deficit).
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PMID:Expressed sequence tag analysis of the response of apple (Malus x domestica'Royal Gala') to low temperature and water deficit. 1829 16

Leaf optical parameters influence light availability at the cellular, leaf, and canopy scale of integration. While recent studies have focused on leaf optical responses to acute plant stress, the effects of changes in plant resources on leaf optics remain poorly characterized. We examined leaf optical and anatomical responses of five temperate deciduous tree species to moderate changes in nutrient and light availability. Spectral reflectance in the visible waveband generally increased at high light, but decreased with increased nutrient availability. Patterns of both spectral reflectance and absorptance were primarily determined by chlorophyll concentration although carotenoid concentration was also influential. While most anatomical features did not explain residual variation in reflectance, cuticle thickness was significantly related to reflectance at complementary angles compared to the angle of incidence. Absorptance did not change with light environment; however, absorption efficiency per unit biomass increased by approximately 40% under low light, due to reduced leaf mass per area. We conclude that changes in resource availability differentially influence leaf optical properties and that such changes are driven primarily by changes in pigment concentrations. The magnitude of leaf optical responses to moderate changes in resource availability was comparable to those of acute stress responses and varied among species.
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PMID:Leaf optical responses to light and soil nutrient availability in temperate deciduous trees. 2165 98