Skin morphological changes in growth hormone deficiency and acromegaly. (41/499)

OBJECTIVE: To evaluate the histomorphology of skin and its appendages, especially eccrine sweat glands, in patients with GH disorders, because reduced sweating ability in patients with growth hormone deficiency (GHD) is associated with increased risk of hyperthermia under stressed conditions. DESIGN AND METHODS: A skin biopsy was obtained from 17 patients with GHD treated with GH, five patients with untreated GHD, 10 patients with active acromegaly and 13 healthy controls. RESULTS: The sweat secretion rate (SSR) was significantly decreased in both the untreated (median 41 mg/30 min, range 9-79 mg/30 min) and the GH-treated (median 98 mg/30 min, range 28-147 mg/30 min) patients with GHD compared with that in controls (median 119 mg/30 min, range 90-189 mg/30 min; P=0.001 and 0.01 respectively). Epidermal thickness was significantly decreased in both untreated (median 39 microm, range 28-55 microm) and GH-treated patients with GHD (median 53 microm, range 37-100 microm), compared with that in controls (median 66 microm, range 40-111 microm; P<0.02). A statistically non-significant tendency towards thinner epidermis (median 59 microm, range 33-83 microm) was recorded in acromegalic patients (P=0.08) compared with controls. There was no significant difference in the area of the sebaceous glands in the biopsies between the three groups and the controls. The area of eccrine sweat gland glomeruli was significantly decreased in the untreated patients with GHD (median 16407 microm2, range 12758-43976 microm2) compared with that in controls (median 29446 microm2, range 13511-128661 microm2; P=0.03), but there was no significant difference between the GH-treated patients with GHD and controls. CONCLUSIONS: We conclude that GH, either directly or via IGF-I, may have both a structural and a functional effect on human skin and its appendages, and that patients with GHD have histomorphological changes in skin compared with controls. Importantly, these changes are not fully reversed despite long-term and adequate GH treatment in patients with childhood onset GHD.  (+info)

Evidence for metaboreceptor stimulation of sweating in normothermic and heat-stressed humans. (42/499)

1. Isometric handgrip (IHG) exercise increases sweat rate and arterial blood pressure, and both remain elevated during post-exercise ischaemia. The purpose of this study was to identify whether the elevation in arterial blood pressure during post-exercise ischaemia contributes to the increase in sweating. 2. In normothermia and during whole-body heating, 2 min IHG exercise at 40% maximal voluntary contraction, followed by 2 min post-exercise ischaemia, was performed with and without bolus intravenous administration of sodium nitroprusside during the ischaemic period. Sodium nitroprusside was administered to reduce blood pressure during post-exercise ischaemia to pre-exercise levels. Sweat rate was monitored over two microdialysis membranes placed in the dermal space of forearm skin. One membrane was perfused with the acetylcholinesterase inhibitor neostigmine, while the other was perfused with the vehicle. 3. In normothermia, IHG exercise increased sweat rate at the neostigmine-treated site but not at the control site. Sweat rate remained elevated during post-exercise ischaemia even after mean arterial blood pressure returned to the pre-IHG exercise baseline. Subsequent removal of the ischaemia stimulus returned sweat rate to pre-IHG exercise levels. Sweat rate during post-exercise ischaemia without sodium nitroprusside administration followed a similar pattern. 4. During whole-body heating, IHG exercise increased sweat rate at both neostigmine-treated and untreated sites. Similarly, regardless of whether mean arterial blood pressure remained elevated or was reduced during post-exercise ischaemia, sweat rate remained elevated during the ischaemic period. 5. These results suggest that sweating in non-glabrous skin during post-IHG exercise ischaemia is activated by metaboreflex stimulation and not via baroreceptor loading.  (+info)

Clinical differences between benign and malignant pheochromocytomas. (43/499)

Most pheochromocytomas can be cured by resection. In view of the unfavourable prognosis for surgical therapy in cases of late tumour detection and malignant tumours, the aim of the present study is to differentiate between typical signs and symptoms of malignant versus benign pheochromocytomas. We investigated the records of 133 patients retrospectively (1967-1998). In cases of benign tumours (104 of 133, mean age 42+/-15.8 years) tumour size was 5.9+/-3.4 cm, and history was 47.4+/-75.4 months. 7.7% of the tumours were extraadrenal, and 77% had paroxysmal manifestations. The other 29 patients (mean age: 39.2+/-21.9 years) had malignant lesions (tumour size: 9.4+/-5.9 cm (p=0.0022); history: 7.4+/-5.6 months (p=0.0137); extraadrenal: 24.1% (p=0.0219); paroxysmal: 37.9% (p=0.0012)). Symptoms of patients with benign tumours were hypertension (80%), headaches (42.3%), sweating (30.8%), tachycardia (26%) and pallor (24%) (Malignant: Hypertension 46%, p=0.0873; headaches 11%, p=0.0008; sweating 11%, p=0.0196; tachycardia 14%, p=0.1961 and pallor 0%, p=0.0010). Abdominal pain and dorsalgia occurred more frequently in malignant pheochromocytomas (26% versus 7%, p=0.0014). Unusually short histories and extraadrenal localization appear to be suspicious for malignancy. The "typical" clinical signs and symptoms occur more frequently in patients with benign tumours and can therefore be regarded as typical signs of benign pheochromocytomas.  (+info)

Nitric oxide synthase inhibition does not affect the exercise-induced arterial hypoxemia in Thoroughbred horses. (44/499)

Because sensitivity of equine pulmonary vasculature to endogenous as well as exogenous nitric oxide (NO) has been demonstrated, we examined whether endogenous NO production plays a role in exercise-induced arterial hypoxemia. We hypothesized that inhibition of NO synthase may alter the distribution of ventilation-perfusion mismatching, which may affect the exercise-induced arterial hypoxemia. Arterial blood-gas variables were examined in seven healthy, sound Thoroughbred horses at rest and during incremental exercise protocol leading to galloping at maximal heart rate without (control; placebo = saline) and with N(omega)-nitro-L-arginine methyl ester (L-NAME) administration (20 mg/kg iv). The experiments were carried out in random order, 7 days apart. At rest, L-NAME administration caused systemic hypertension, pulmonary hypertension, and bradycardia. During 120 s of galloping at maximal heart rate, significant arterial hypoxemia, desaturation of hemoglobin, hypercapnia, hyperthermia, and acidosis occurred in the control as well as in NO synthase inhibition experiments. However, statistically significant differences between the treatments were not found. In both treatments, exercise caused a significant rise in hemoglobin concentration, but the increment was significantly attenuated in the NO synthase inhibition experiments, and, therefore, arterial O(2) content (Ca(O(2))) increased to significantly lower values. These data suggest that, whereas L-NAME administration does not affect pulmonary gas exchange in exercising horses, it may affect splenic contraction, which via an attenuation of the rise in hemoglobin concentration and Ca(O(2)) may limit performance at higher workloads.  (+info)

Psychiatric morbidity and the menopause; screening of general population sample. (45/499)

A survey of 539 women from the general population indicated a high prevalence of minor psychiatric illness in women aged 40-55 years. There was evidence of an increase in psychiatric morbidity occurring before the menopause and lasting until about one year after menstrual periods had ended. Vasomotor symptoms increased dramatically when periods stopped and persisted up to five years after the menopause. Both these features seemed to have a clear relation to the menopause but not the same relation. The findings suggested that further investigation of the relation between perimenopausal hormonal changes and psychiatric morbidity should be directed towards premenopausal women. Environmental factors, particularly in relation to children, seemed to be associated with increased psychiatric morbidity at this time of life.  (+info)

Dehydration and body fluid-regulating hormones during sweating in warm (38 degrees C) fresh- and seawater immersion. (46/499)

Body weight (BW) reductions of more than 4 kg have been observed during diving with the open hot water suit, a technique in which heated seawater (SW) continuously floods the skin surface. To test the hypothesis that osmotic effects may be involved in these fluid-loss processes, head-out immersion experiments in 38 degrees C freshwater (FW) and SW for 4 h were performed. Average BW reduction was 2.5 and 1.9 kg in SW and FW head-out immersion, respectively (P < 0.01). Atrial natriuretic peptide increased during the first 30 min of SW immersion (5.6-13.4 pmol/l, P < 0.01) followed by a reduction to 7.6 pmol/l (P < 0.01). This paralleled an initial decrease in aldosterone (from 427 to 306 pmol/l, P < 0.05) followed by an increase to 843 pmol/l (P < 0.01). The effects of temperature on fluid loss were studied in thermoneutral (34.5 degrees C) and 38 degrees C SW for 2 h. In thermoneutral SW, calculated sweat production was negligible (0.05 kg) compared with 1.2 kg in warm SW. We recommend that, if a dive is planned to last for more than 4 h, a mandatory break for fluid intake should be incorporated in the diving regulations.  (+info)

Characteristics of body heat balance of paraplegics during exercise in a hot environment. (47/499)

The purpose of this investigation was to clarify the characteristics of body temperature regulation in paraplegics due to spinal cord injury (SCI) during an arm cranking exercise in a hot environment. Twelve paraplegics with lesions located between Th3 and L1,2 and seven able-bodied subjects (AB) participated in this study. The subjects were exposed to a hot (33 degrees C) or a moderate temperature (25 degrees C) environment for one hour and during the last 10 min of the exposure, the subjects performed arm cranking exercises at an exercise intensity of 40 W. The skin temperatures at the chest, the upper arm, the thigh and the calf, the tympanic membrane temperature (Tty), and the skin blood flow of the thigh (SBFT) were continuously monitored during the experiment. Although no systematical variation was found in the Tty at 25 degrees C, the Tty at 33 degrees C in paraplegics during exercise was significantly greater than that at rest (P < 0.01), which indicated a pronounced heat stress for paraplegics at 33 degrees C. SBFT of paraplegics with high lesions of the SCI remained unchanged during the experiment at 25 degrees C and 33 degrees C, while paraplegics with low lesions in this study showed consecutive increases in SBFT during exercise in both environmental conditions similar to AB. The increased core temperature in paraplegics with high lesions was considered to be due to a lack of sweat response and vasomotor activity in the paralyzed area. On the basis of the findings in this study, it can be suggested that high core temperature without any increment of SBFT may be characterized as body heat balance of paraplegics with high lesions during exercise in a hot environment.  (+info)

Absence of arterial baroreflex modulation of skin sympathetic activity and sweat rate during whole-body heating in humans. (48/499)

1. Prior findings suggest that baroreflexes are capable of modulating skin blood flow, but the effects of baroreceptor loading/unloading on sweating are less clear. Therefore, this project tested the hypothesis that pharmacologically induced alterations in arterial blood pressure in heated humans would lead to baroreflex-mediated changes in both skin sympathetic nerve activity (SSNA) and sweat rate. 2. In seven subjects mean arterial blood pressure was lowered (approximately 8 mmHg) and then raised (approximately 13 mmHg) by bolus injections of sodium nitroprusside and phenylephrine, respectively. Moreover, in a separate protocol, arterial blood pressure was reduced via steady-state administration of sodium nitroprusside. In both normothermia and heat-stress conditions the following responses were monitored: sublingual and mean skin temperatures, heart rate, beat-by-beat blood pressure, skin blood flow (laser-Doppler flowmetry), local sweat rate and SSNA (microneurography from peroneal nerve). 3. Whole-body heating increased skin and sublingual temperatures, heart rate, cutaneous blood flow, sweat rate and SSNA, but did not change arterial blood pressure. Heart rate was significantly elevated (from 74 +/- 3 to 92 +/- 4 beats x min(-1); P < 0.001) during bolus sodium nitroprusside-induced reductions in blood pressure, and significantly reduced (from 92 +/- 4 to 68 +/- 4 beats x min(-1); P < 0.001) during bolus phenylephrine-induced elevations in blood pressure, thereby demonstrating normal baroreflex function in these subjects. 4. Neither SSNA nor sweat rate was altered by rapid (bolus infusion) or sustained (steady-state infusion) changes in blood pressure regardless of the thermal condition. 5. These data suggest that SSNA and sweat rate are not modulated by arterial baroreflexes in normothermic or moderately heated individuals.  (+info)