Impaired thermoregulation against cold in capsaicin pretreated rats

A study was made of the effects of pretreatment with fractionated capsaicin on the changes in body temperature (Tb) induced in rats by exposure to cold and to warm environments, and by administration of histamine (40 mg X kg-1) or of pentobarbital (20 mg X kg-1). At the ambient temperature of 22 degrees C the Tb of capsaicin pretreated rats was lower than that of rats treated only with solvent (p less than 0.001). The capsaicin pretreated rats showed impairment of thermoregulation at both high and low environmental temperatures: their Tb rose to a higher level in a warm environment, while in a cold environment their Tb was lower than that of the control rats. Histamine and pentobarbital caused larger drops in the Tb of capsaicin pretreated rats than in the controls. These findings challenge the concept that capsaicin treatment acts exclusively on thermoregulatory mechanisms concerned with warmth sensation.     

Responses of skin blood vessels to bradykinin, histamine and 5-hydroxytryptamine

1. The responses of human cutaneous blood vessels to intradermal injection of bradykinin, histamine and 5-hydroxytryptamine (serotonin) are studied in order to evaluate the ability of these agents to mediate the vascular changes of sustained acute inflammation in the skin.

2. Bradykinin produces erythema, owing to a direct effect on blood vessels, and wealing. Dose—response studies indicate that bradykinin is more potent than serotonin or histamine in respect of wealing.

3. The response to serotonin differs qualitatively as well as quantitatively according to dose. High doses cause wealing and erythema with the characteristics of an axon reflex flare, but low doses produce erythema by a local effect without wealing.

4. Using the technique of arterial occlusion, the occurrence of tachyphylaxis in respect of wealing was demonstrated with histamine and serotonin, but not with bradykinin. This evidence suggests that of the three agents, only bradykinin can mediate increased vascular permeability in sustained acute inflammation.

5. The specificity of tachyphylaxis and the failure of anti-histamine to antagonize bradykinin wealing suggest that bradykinin and histamine act on separate blood vessel receptors.

6. Corticosteroids do not inhibit wealing due to a wide range of doses of bradykinin. The anti-inflammatory activity of corticosteroids may therefore be due to reduced formation of kinins.

     

Response to exercise and ambulatory blood pressure monitoring in essential hypertension

To evaluate the relationship of ambulatory blood pressure (ABP) recording and blood pressure response to exercise, 58 essential hypertensive patients, not taking any drugs, had symptom-limited treadmill stress test (TST) within 48-96 hours of ABP, TST time, blood pressure increase, decrease, mode of increase and decrease, were independent of ABP systolic (SBP) and diastolic blood pressure (DBP) over 24 hours, day time and night time (p = ns). SBP decrease immediately after exercise were independent of ABP data. TST achieved heart rate was related to both 24 hours SBP (r = -0.64, p = 0.00005) and DBP (r = -0.55, p = 0.00001) in both day (r = -0.64, p = 0.00001 and r = -0.54, p = 0.002) and night (r = -0.52, p = 0.0001 and r = -0.46, p = 0.003) time periods. Therefore patients with achieved heart rate < 100% (n = 18) had higher 24 hour SBP (148 vs 132 +/- 2 mm Hg, p = 0.0006) and DBP (92.4 +/- 6.4 vs 84 +/- 6.2 mm Hg, P = 0.006) day and night. It is concluded that there is no overlap of diagnostic information using blood pressure. Values in TST or ABP although achieved heart rate in exercise is inversely related to severity of hypertension.     

跨区供血皮瓣的研究进展

近年来随着临床解剖学研究的深入,在皮瓣血供研究方面取得了新的进展,特别是跨区供血皮瓣的提出,为显微外科皮瓣移植增添了更加简捷的修复手段,打破了皮瓣原有位区血供范围的限制,使得皮瓣血管蒂更长、修复范围更广,拓宽了传统轴型皮瓣修复领域。1跨区供血皮瓣理论的确立与临床意义 Taylor[1](1987)对皮肤、皮下组织及其下深部组织所构成     

Effect of chronic capsaicin and guanethidine treatment on skin blood flow of the rat

Using a non-invasive laser Doppler velocimetry technique to measure skin blood flow in the rat skin, we have shown that chronic treatment with capsaicin inhibited the vasodilator response to a non-pathological, local heat (44°C, 20 min duration) stimulus. However, sympathectomy, accomplished with chronic treatment of guanethidine, had no effect on this heat-induced vasodilation. Topical steroids have also been shown to inhibit this response thus, since the heat-dilator response appears from these results to be brought about by the release of sensory neuropeptides, the sensory neuron may be a target for topical steroid action.     

Response of salivary peroxidase to exercise intensity

Oral peroxidase, one of the most important salivary antioxidant enzymes, is subjected to alternation due to various body conditions. The aim of this study was to assess the effect of exercise intensity on salivary peroxidase activity. Using a randomized design, ten healthy male university students (mean age, 23.22; s _x = 2.34 years) completed treadmill runs with initial velocity 6.73 km/h at the rate of 1.58 km/h increase every 3 min until exhaustion. Unstimulated whole saliva collected over a 5-min period in pre-weighed tubes before, immediately after exercise, and 1 h after exercise was analyzed for total protein and saliva peroxidase activity. The saliva flow rate ranged from 0.08 to 1.40 ml min⁻¹ at rest and was not significantly affected by the exercise. Peroxidase activity in each sample was measured using 4-amino antipyrine as substrate. In the incremental exhaustion run and also at 75% VO_2max, the secretion rates of peroxidase increased. No significant changes in saliva flow rate were observed in any treadmill run. Treadmill runs at 75% VO_2max and to exhaustion increased the activity of peroxidase immediately after exercise which decreased after 1 h. It was concluded that short-duration, high-intensity exercise increases the activity rate of peroxidase despite no change in the saliva flow rate. These effects appear to be associated with changes in sympathetic activity and not the hypothalamic pituitary adrenal axis.     

The cholinergic pathway to cerebral blood vessels

The application of cobalt chloride to the peripheral cut end of the greater superficial petrosal nerve (g.s.p.n.) in rats revealed that only a few fibers in the plexus of nerves on the adventitial surface of the internal carotid artery were in axonal continuity with the g.s.p.n. A similarly small contribution of cholinergic fibers to cerebral blood vessels from this nerve was suggested by the observation that section of the g.s.p.n. resulted in an insignificant reduction in the density of the AChE-staining plexus in the internal carotid and cerebral arteries and in the incidence of at most 2% degenerate terminals of those observed on the middle cerebral artery. Alternative explanations of the results are discussed: that the AChE-staining fibers are postganglionic, that the time course for degeneration is unusually slow and that non-cholinergic fibers stain non-specifically for AChE. It is concluded that a cholinergic dilator pathway is most probably carried by the g.s.p.n. but that it is not unique.     

The cholinergic pathway to cerebral blood vessels

Summary The effect of stimulating the greater superficial petrosal nerve (g.s.p.n.) upon retroglenoid venous blood flow has been tested in anaesthetized, paralysed and artificially ventilated rats. In 11 out of 15 tests, blood flow increased by an average of 25% with a time to peak response of 28 s. This response was abolished with the injection of atropine 0.1 mg kg^–1 injected intra-arterially. With both petrosal nerves intact, the administration of 6–7% CO₂ in air or 15% O₂ in N₂ caused average increases in blood flow of 105% and 45% respectively. These responses were not affected by bilateral section of the g.s.p.n. Similar experiments were carried out in 5 anaesthetized, spontaneously breathing rabbits in which, in addition toPaCO₂ andPaO₂,PO₂,PCO₂ and blood flow in the caudate nucleus were measured continuously using chronically implanted mass spectrometer catheters and heated thermistors. Caudate nucleus blood flow increased in response to hypoxia and hypercapnia and this response was not significantly affected by section of one or both g.s.p.n., sinus or vagus nerves. With section of sinus and vagus nerves, blood flow changed passively with arterial pressure.     

Response of erythrocytic 2,3-diphosphoglycerate to strenuous exercise

Summary Since increases of erythrocytic 2,3-diphosphoglycerate (2,3-DPG) have been shown to enhance the release of oxygen from hemoglobin, experiments were designed to evaluate the response of 2,3-DPG to two different workloads in 13 fasted human subjects. No significant mean change in 2,3-DPG was found following 16 min of strenuous exercise on a bicycle ergometer, but when the subjects were subjected later to a greater workload for 20 min, there was a significant mean decrease in 2,3-DPG despite much individual variation. In addition, there was a significant positive correlation of 2,3-DPG reduction with increases in postexercise lactate, and a significant inverse correlation of oxygen consumption during exercise with postexercise lactate. The data suggest that the 2,3-DPG mechanism may not be compensating in exercise when the workload requires a preponderance of anaerobic metabolism promoting lactacidaemia.     

Response of human skin equivalents to Sarcoptes scabiei

Studies have shown that molecules in an extract made from bodies of the ectoparasitic mite, Sarcoptes scabiei De Geer, modulate cytokine secretion from cultured human keratinocytes and fibroblasts. In vivo, in the parasitized skin, these cells interact with each other by contact and cytokine mediators and with the matrix in which they reside. Therefore, these cell types may function differently together than they do separately. In this study, we used a human skin equivalent (HSE) model to investigate the influence of cellular interactions between keratinocytes and fibroblasts when the cells were exposed to active/burrowing scabies mites, mite products, and mite extracts. The HSE consisted of an epidermis of stratified stratum corneum, living keratinocytes, and basal cells above a dermis of fibroblasts in a collagen matrix. HSEs were inoculated on the surface or in the culture medium, and their cytokine secretions on the skin surface and into the culture medium were determined by enzyme-linked immunosorbent assay. Active mites on the surface of the HSE induced secretion of cutaneous T cell-attracting chemokine, thymic stromal lymphopoietin, interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist (IL-1ra), IL-6, IL-8, monocyte chemoattractant protein-1, granulocyte/macrophage colony-stimulating factor, and macrophage colony-stimulating factor. The main difference between HSEs and monocultured cells was that the HSEs produced the proinflammatory cytokines IL-1alpha and IL-1beta and their competitive inhibitor IL-1ra, whereas very little of these mediators was previously found for cultured keratinocytes and fibroblasts. It is not clear how the balance between these cytokines influences the overall host response. However, IL-1ra may contribute to the depression of an early cutaneous inflammatory response to scabies in humans. These contrasting results illustrate that cell interactions are important in the host's response to burrowing scabies mites.