Effect of trauma on plasma glucagon and insulin concentrations in sheep.
Portal plasma glucagon and insulin concentrations were measured before and after acute trauma (liver biosy). The trauma was sufficient to increase glucagon concentrations and depress insulin concentrations. These changes were associated with a marked hyperglycemia. Infusion of glucagon was insufficient to prevent stress inhibition of insulin secretion. The stimulation of glucagon secretion and inhibition of insulin secretion were of about one hour duration. These findings indicate that glucagon and insulin in conjunction with the nervous system may play an important role in the development of stress related hyperglycemia. (+info)
Nitric oxide stimulates the stress-activated protein kinase p38 in rat renal mesangial cells.
Nitric oxide (NO) has gained increased attention as a diffusible universal messenger that plays a crucial role in the pathogenesis of inflammatory and autoimmune diseases. Recently, we reported that exogenous NO is able to activate the stress-activated protein kinase (SAPK) cascade in mesangial cells. Here, we demonstrate that exposure of glomerular mesangial cells to compounds releasing NO, including spermine-NO and (Z)-1- (N-methyl-N-[6-(N-methylammoniohexyl)amino]diazen)-1-ium-1,2-diolate (MAHMA-NO), results in an activation of the stress-activated p38-mitogen-activated protein kinase (p38-MAPK) cascade as measured by the phosphorylation of the activator of transcription factor-2 (ATF2) in an immunocomplex kinase assay. Activation of the p38-MAPK cascade by a short stimulation (10 min) with the NO donor MAHMA-NO causes a large increase in ATF2 phosphorylation that is several times greater than that observed after stimulation with interleukin-1beta, a well-known activator of the p38-MAPK pathway. Time course studies reveal that MAHMA-NO causes rapid and maximal activation of p38-MAPK after 10 min of stimulation and that activation declines to basal levels within 60 min. The longer-lived NO donor spermine-NO causes a comparable rapid activation of the p38-MAPK pathway; however, the increased activation state of p38-MAPK was maintained for several hours before control values were reattained after 24 h of stimulation. Furthermore, the NO donors also activated the classical extracellular signal-regulated kinase (ERK) p44-MAPK cascade as shown by phosphorylation of the specific substrate cytosolic phospholipase A2 in an immunocomplex kinase reaction. Both MAHMA-NO and spermine-NO cause a rapid activation of p44-MAPK after 10 min of stimulation. Interestingly, there is a second delayed peak of p44-MAPK activation after 4-24 h of stimulation with NO donors. These results suggest that there is a differential activation pattern for stress-activated and mitogen-activated protein kinases by NO and that the integration of these signals may lead to specific cell responses. (+info)
Effects of soybean oil emulsion and eicosapentaenoic acid on stress response and immune function after a severely stressful operation.
OBJECTIVE: To investigate the effects of soybean oil emulsion and oral or enteral administration of eicosapentaenoic acid (EPA) on stress response, cytokine production, protein metabolism, and immune function after surgery for esophageal cancer. SUMMARY BACKGROUND DATA: It has been reported that safflower oil, rich in n-6 polyunsaturated fatty acid (n-6 PUFA), affects the survival rate of septic animals and decreases the immune function. It has also been reported that the administration of fish oil, in contrast, reduces these stress responses and stress-induced immunosuppression. In humans, the effects of soybean oil emulsion and the administration of EPA on stress response and immune function after surgery have not been established. METHODS: Patients who underwent esophagectomy with thoracotomy were divided into three groups. Seven patients were fed by total parenteral nutrition (TPN) with soybean oil emulsion, which accounted for 20% of total calories. Seven patients were given oral or enteral administration of 1.8 g/day EPA, in addition to TPN with soybean oil emulsion. Nine patients served as the control group; these patients received fat-free TPN. Serum interleukin-6 (IL-6), C-reactive protein, concanavalin A (con A)- or phytohemagglutinin (PHA)-stimulated lymphocyte proliferation, natural killer cell activity, and stress hormones were measured. RESULTS: The postoperative level of serum IL-6 was significantly higher in the group receiving soybean oil emulsion than in the fat-free group. Oral or enteral supplementation of EPA with soybean oil emulsion significantly reduced the level of serum IL-6 compared with the patients receiving soybean oil emulsion. Con A- or PHA-stimulated lymphocyte proliferation decreased significantly on postoperative day 7 in all groups of patients. The supplementation of EPA with soybean oil emulsion significantly improved the lymphocyte proliferation and natural killer cell activity on postoperative day 21 compared with the group receiving soybean oil emulsion. CONCLUSIONS: Soybean oil emulsion amplifies, and the supplementation of EPA reduces, the stress response and stress-induced immunosuppression. (+info)
Mechanical stimulation of starfish sperm flagella.
1. The responses of starfish sperm flagella to mechanical stimulation with a microneedle were analysed. Flagellar movement was recorded by high-speed microcinematography and by stroboscopic observation. 2. The amplitude of the bending wave of a flagellum was restricted over its entire length when the microneedle was brought near to the flagellum at its proximal region. Beyond the restricted part, the amplitude of the wave, and the bend angle, became smaller than those of a normally beating flagellum, while the curvature was practically unchanged. 3. When the tip of the microneedle was in contact with the flagellum, propagation of the bending wave beyond the microneedle was inhibited. The part of the flagellum between the base and the microneedle continued beating in some cases and stopped beating in other cases. The flagellum beyond the arrested part stopped beating and remained straight. When the microneedle was removed, the bending wave which existed in the part of the flagellum proximal to the microneedle, or the wave which was passively formed de novo at the time of the removal of the microneedle, propagated over the arrested part towards the tip. 4. A flagellum amputated by a microneedle in a medium containing ATP continued beating with a small amplitude, small curvature, small bend angle and low frequency. When the amputated flagellum was passively bent by a microneedle at the region near the point of amputation, this bend propagated towards the tip with a constant bend angle. 5. The beating frequency of the flagellum could be modulated by the application of a rhythmic external force generated by vibrating a microneedle near the flagellum. The beating was completely synchronized with vibration of the microneedle in the frequency range from 23 Hz to 43 Hz. (+info)
Influence of a new antiulcer agent, ammonium 7-oxobicyclo (2, 2, 1) hept-5-ene-3-carbamoyl-2-carboxylate (KF-392) on gastric lesions and gastric mucosal barrier in rats.
Antiulcer effects of KF-392 were studied in several experimental gastric ulcer models in rats. It was found that KF-392 given orally at 1.0 to 5.0 mg/kg had a marked suppression on the developments of Shay ulcer as well as the aspirin-, stress-, and reserpine-induced gastric lesions. The influence of KF-392 on gastric mucosal barrier was also studied. A back diffusion of H+ into the gastric mucosa and a fall of transmucosal potential difference were induced with KF-392 given orally at the above mentioned doses. KF-392 given s.c. at 5.0 mg/kg showed no inhibition of Shay ulcer and no induction of back diffusion of H+ into the gastric mucosa. (+info)
The Ca2+ channel blockade changes the behavioral and biochemical effects of immobilization stress.
We investigated how the effects of chronic immobilization stress in rats are modified by Ca2+ channel blockade preceding restraint sessions. The application of nifedipine (5 mg/kg) shortly before each of seven daily 2 h restraint sessions prevented the development of sensitized response to amphetamine as well as the stress-induced elevation of the densities of L-type Ca2+ channel in the hippocampus and significantly reduced the elevation of the densities of [3H]nitrendipine binding sites in the cortex and D1 dopamine receptors in the limbic forebrain. Neither stress, nor nifedipine affected the density of alpha 1-adrenoceptors and D1 receptors in the cerebral cortex nor D2 dopamine receptors in the striatum. A single restraint session caused an elevation of blood corticosterone level that remained unaffected by nifedipine pretreatment, but the reduction of this response during the eighth session was significantly less expressed in nifedipine-treated rats. We conclude that L-type calcium channel blockade prevents development of several stress-induced adaptive responses. (+info)
The effects of low-copper diets with or without supplemental molybdenum on specific immune responses of stressed cattle.
Angus bull calves (n = 42; 7 mo of age; 254 kg initial BW) were used to investigate the effects of dietary Cu and Mo on immune function of stressed cattle. Randomly selected calves (n = 22) were injected with 90 mg of Cu as Cu glycinate 28 d before weaning and castrated at weaning. These calves received 7.5 and 5 mg of supplemental Cu/kg of DM during a 41-d receiving phase and a 196-d growing phase, respectively. The remainder of the steers received no supplemental Cu during the experiment. Copper-supplemented steers had adequate Cu status at weaning, whereas unsupplemented calves were marginally Cu-deficient. Cell-mediated response to intradermal injection of phytohemagglutinin was not affected by dietary treatment during the receiving phase. During the growing phase, half of the steers in each Cu treatment were given 5 mg of supplemental Mo/kg of DM. Copper supplementation increased (P<.05) humoral response to ovalbumin injected on d 133 of the growing phase. On d 168 of the growing phase, calves receiving only supplemental Mo were severely Cu-deficient based on plasma and liver Cu concentrations. The other treatment groups had adequate Cu status. Before feeding on d 168 of the growing phase, half of the steers were loaded onto trailers and transported 2.5 h, and they remained on the trailers an additional 9.5 h. Humoral response to porcine erythrocytes (PRBC) and delayed-type hypersensitivity (DTH) to dinitrochlorobenzene was tested at the end of the stress period. There was a Cu x stress interaction for humoral response to PRBC, with Cu decreasing antibody titers in unstressed calves and increasing titers in stressed steers. Stressed steers had lower (P = .03) ADG during the 28 d following stress. The results of this study indicate that Cu deficiency and 5 mg of supplemental Mo/kg of DM do not dramatically alter the specific immunity of stressed cattle. (+info)
Individual and organizational predictors of depression in general practitioners.
BACKGROUND: High levels of stress and depression are seen in both general practitioners (GPs) and hospital doctors, and this has implications for patient care. It is therefore important to discover the individual and organizational causes of elevated symptoms so they can be tackled. AIM: To discover the relative importance of individual characteristics measured 10 years earlier compared with current organizational stressors in predicting depression in GPs. METHOD: Longitudinal questionnaire study, using data from those of the original cohort of 318 medical students who are now GPs (n = 131), considering perceptions of current stressors and comparing through regression analyses the relative strength of early personality and mood with current organizational factors of sleep, hours worked, and practice size in predicting current depression levels. RESULTS: There were 22 (17%) stressors scoring above threshold for depression. Relationships with senior doctors and patients are the main reported stressors, followed by making mistakes and conflict of career with personal life. The predictors of symptom levels varied for men and women. In men, depression and self-criticism as students, and current sleep levels; and in women, sibling rivalry and current alcohol use, were the main predictors: in men, 27% of the variance was accounted for by early dispositional factors alone compared with 14% in women. A model is suggested linking sleep loss with workplace stressors, self-critical cognitions, and depression. CONCLUSION: Interventions can be made throughout training, targeting self-criticism and recognizing early depression, while later addressing the organizational stressors, particularly work relationships and sleep patterns. (+info)