Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to determine the effect of controlled hypotension on subcutaneous and cutaneous haemodynamics in humans. Moderate hypotension was achieved with nitroglycerin (NTG) and sodium nitroprusside (SNP) infusion during narconeuroleptanalgesia in seven patients. Subcutaneous and cutaneous blood flow were measured by a superficial and deep heat clearance (HC) technique. The mean arterial pressure (BPa) decreased by 23%-30% and heart rate (fc) increased but only during NTG infusion (+22%; P less than 0.02). Subcutaneous and cutaneous blood flows remained unchanged despite a significant decrease in calculated cutaneous resistance (NTG: -26%, P less than 0.01; SNP: -34%, P less than 0.02] and subcutaneous vascular resistance changed only with SNP (-31%, P less than 0.02). After hypotension was discontinued the subcutaneous blood flow decreased (-13%, P = 0.05), whereas subcutaneous vascular resistance returned to its control values. An inverse relationship was found between fc and BPa (NTG: r = -0.525, P less than 0.01; SNP: r = -0.622, P less than 0.01) as well as with subcutaneous blood flow (NTG: r = -0.653, P less than 0.001; SNP: r = -0.573, P less than 0.01). In addition, we found oscillatory changes in deep HC values which differed in magnitudes (NTG 0.22 (SEM 0.09) W.m-1.degree C-1 vs SNP 0.42 (SEM 0.1) W.m-1.degrees C-1, P less than 0.01) and frequencies (NTG 0.02 (SEM 0.006) Hz vs SNP 0.01 (SEM 0.002) Hz, P less than 0.01). Despite unchanged blood flow, the effects of controlled hypotension on cutaneous and subcutaneous haemodynamics were different depending on the type of drug. These differences may have been related to counterregulatory responses and/or to direct vascular effects.
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PMID:Effects of hypotension on cutaneous and subcutaneous blood flow in anaesthetized humans. 176 Oct 9

With a multibarrel assembly combining one carbon fiber micropipette as recording electrode and 6 pipettes for microiontophoretic application of drugs, the activity of neurons in the preoptic and anterior hypothalamic (POAH) region was extracellularly recorded in situ in conscious ducks implanted chronically with a device permitting hypothalamic thermal stimulation. Among 355 neurons 17% were identified as warm-responsive (warm units) and 20% as cold-responsive (cold units). In 58 warm and 56 cold units control discharge rates at 40 degrees C local temperature (F40) and temperature coefficients (delta F/delta T) were determined and presented as means +/- SEM. The F40 values of warm units (35.2 +/- 2.3 Imp . s-1) were significantly higher than of cold units (16.3 +/- 1.8 Imp . s-1). The delta F/delta T values (+1.77 +/- 0.15 and -1.77 +/- 0.19 Imp . s-1 . degree C-1) of warm and cold units were not different in absolute terms. In pilot experiments either activation or inhibition by lowering whole-body temperature was observed in both warm and cold units. Microiontophoretic application of one or more of the amines acetylcholine (ACh), 5-hydroxytryptamine (5-HT), and noradrenaline (NA) to warm and cold units revealed differences in their responsiveness to ACh, which more consistently stimulated cold units. NA inhibited the majority of warm units; 5-HT stimulated the majority of cold units. In both warm and cold units NA and ACh differed in their actions, with the latter amine more consistently producing activation.
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PMID:Thermal characterization and transmitter analysis of single units in the preoptic and anterior hypothalamus of conscious ducks. 289 54

Well matched unacclimatised older (age 55-68, 4 women, 2 men) and younger (age 19-30, 4 women, 2 men) subjects performed 75 min cycle exercise (approximately 40% VO2max) in a hot environment (37 degrees C, 60% rh). Rectal temperature (Tre), mean skin temperature (Tsk), arm blood flow (ABF, strain gauge plethysmography), and cardiac output (Q, CO2 rebreathing) were measured to examine age-related differences in heat-induced vasodilatation. Tre and Tsk rose to the same extent in each group during the exposure. There was no significant intergroup difference in sweat rate (older: 332 +/- 43 ml.m-2.h-1, younger: 435 +/- 49 ml.m-2.h-1; mean +/- SEM). However, the older subjects responded to exercise in the heat with a lower ABF response which could be attributed to a lower Q for the same exercise intensity. The slope of the ABF-Tre relationship was attenuated in the older subjects (9.3 +/- 1.3 vs 17.9 +/- 3.3 ml.100 ml-1.min-1.degrees C-1, p less than 0.05), but the Tre threshold for vasodilatation was about 37.0 degrees C for both groups. These results suggest an altered control of skin vasodilatation during exercise in the heat in older individuals. This attenuated ABF response appears to be unrelated to VO2max, and may reflect an age-related change in thermoregulatory cardiovascular function.
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PMID:Control of heat-induced cutaneous vasodilatation in relation to age. 334 87

The mammalian fetus produces significant quantities of heat. This passes to the mother principally through the placenta and to a lesser extent via a pathway comprising the skin, amniotic fluid, and uterine wall. To assess the importance of the lesser pathway, temperature responses were recorded in 7 near-term fetal sheep after intrauterine ventilation with oxygen, after snaring the umbilical cord to block the placental route, and following fetal death. Four distinguishing characteristics of responses were observed: fetal temperature rose 0.10 +/- 0.03 (SEM) degrees C after oxygenation; it rose progressively an additional 0.9 +/- 0.1 degrees C during the 90-min interval after cord snaring; amniotic fluid temperature rose slowly until it was about midway between fetal and maternal temperature; and after fetal death, fetal amniotic fluid temperatures fell slowly. In a simple mathematical model with constant parameters these results could not be explained fully. It was necessary to assume that heat production rose with increased oxygenation and elevated body temperature and that ventilation increased heat transfer through the amniotic fluid, as would occur if chest wall movement were stirring the fluid. Using the model, the value for heat conductance from fetal skin to amniotic fluid was estimated to be 10.5 watts degrees C-1 under basal conditions.
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PMID:Temperature responses following ventilation of the fetal sheep in utero. 355 61

Slow reacting substance(s) of anaphylaxis (SRS-A) was isolated from both human (lung) and rat sources and compared with three synthetic SRS-As of known structure-leukotrienes (LTs) C-1, C-2, and D. Reversed-phase liquid chromatography was used both as a final purification step and a means of comparison of biologically derived and synthetic substances. Two major peaks of SRS-A activity of both rat and human origin corresponded chromatographically with LTC-1 and LTD, respectively, and had equivalent specific activities on the guinea pig ileum. With guinea pig ileum, the specific activities (units/pmol) for synthetic leukotrienes and anaphylactic peaks were (mean +/- SEM): synthetic LTC-1, 1.93 +/- 0.13; SRS-A(rat) peak I, 1.69 +/- 0.43; synthetic LTD, 6.10 +/- 1.15; SRS-A(rat) peak II, 7.14 +/- 0.51; and SRS-A(hu) peak II, 1.90. Both synthetic LTC-1 and LTD and their SRS-A natural counterparts had a preferential contractile activity on guinea pig peripheral airway compared to central airways and were at least 200 times more active than histamine on peripheral airways on a molar basis. Leukotriene D is the major SRS-A of human lung and accounts for almost all of the biological activity. It likely is formed from leukotriene C-1 in vivo by an enzymic process of the well-known gamma-glutamyltransferase type.
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PMID:Slow reacting substances of anaphylaxis: identification of leukotrienes C-1 and D from human and rat sources. 610 93

Thermoregulatory sweating [total body (msw,b), chest (msw,c) and thigh (msw,t) sweating], body temperatures [oesophageal (T(oes)) and mean skin temperature (Tsk)] and heart rate were investigated in five sleep-deprived subjects (kept awake for 27 h) while exercising on a cycle (45 min at approximately 50% maximal oxygen consumption) in moderate heat (T(air) and T(wall) at 35 degrees C). The msw,c and msw,t were measured under local thermal clamp (Tsk,l), set at 35.5 degrees C. After sleep deprivation, neither the levels of body temperatures (T(oes), Tsk) nor the levels of msw,b, msw,c or msw,t differed from control at rest or during exercise steady state. During the transient phase of exercise (when Tsk and Tsk,l were unvarying), the msw,c and msw,t changes were positively correlated with those of T(oes). The slopes of the msw,c versus T(oes) or msw,t versus T(oes) relationships remained unchanged between control and sleep-loss experiments. Thus the slopes of the local sweating versus T(oes) relationships (msw,c and msw,t sweating data pooled which reached 1.05 (SEM 0.14) mg.cm-2.min-1.degree C-1 and 1.14 (SEM 0.18) mg.cm-2.min-1.degree C-1 before and after sleep deprivation) respectively did not differ. However, in our experiment, sleep deprivation significantly increased the T(oes) threshold for the onset of both msw,c and msw,t (+0.3 degrees C, P < 0.001). From our investigations it would seem that the delayed core temperature for sweating onset in sleep-deprived humans, while exercising moderately in the heat, is likely to have been due to alterations occurring at the central level.
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PMID:Regulation of local sweating in sleep-deprived exercising humans. 835 55

Polycythaemia has been shown to improve physical performance, possibly due to increased arterial oxygen transport. Enhanced thermoregulatory function may also accompany this manipulation, since a greater proportion of the cardiac output becomes available for heat dissipation. We further examined this possibility in five trained men, who participated in three-phase heat stress trials (20 min rest, 20 min cycling at 30% peak power (Wpeak) and 20 min at 45% Wpeak at 38.3 (SEM 0.7) degrees C [relative humidity 41.4 (SEM 2.9)%]. Trials were performed during normocythaemia (control) and polycythaemia, obtained by reinfusion of autologous red blood cells and resulting in significant elevation of arterial oxygen transport. During the polycythaemic trials, the subjects demonstrated diminished thermal strain, as evidenced by a significant reduction in cardiac frequency (fc: 12 beats.min-1 lower throughout the test; P < 0.05), and reduced auditory canal temperatures (Tac) during the latter 20-min phase (P < 0.05). Forearm sweat onset was more rapid (363.0 compared to 1083.0 s; P < 0.05), and forearm sweat rate (msw) sensitivity was elevated from 1.80 to 2.91.mg.cm-2.min-1.degrees C-1 (P < 0.05). Forehead msw was depressed during the final 20 min, while forearm msw was greater during all test phases, averaging 0.94 and 1.20 mg.cm-2.min-1, respectively, over the 60 min. Skin blood flows for the upper back, upper arm and forearm were reduced (P < 0.05). Polycythaemia enhanced thermoregulation, through an elevation in forearm sweat sensitivity and msw, but not via increased cutaneous blood flow. These modifications occurred simultaneously with decreases in fc and Tac, resulting in greater thermal tolerance.
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PMID:Thermal tolerance following artificially induced polycythaemia. 856 73

To understand the changes induced by uremia in the epiphyseal growth plate, two studies were performed in young rats. In study 1, the morphological features of the tibial growth cartilage of stunted rats with different degrees of reduction of renal function were analyzed 2 weeks after nephrectomy and compared with control rats. There was a negative ( r=-0.549, P<0.05) correlation between serum urea nitrogen (SUN) concentrations and longitudinal growth rate. The heights (mean+/-SEM) of growth cartilage (564+/-32 vs. 366+/-9 microm) and its hypertrophic zone (321+/-25 vs. 157+/-6 microm) were greater ( P<0.05) in uremic than control rats and were highly and positively correlated ( r=0.604, P<0.03 and r=0.706, P<0.01) with SUN levels. In study 2, the time course of growth plate alterations was investigated in uremic rats sacrificed 1 (NX-1), 2 (NX-2), and 4 weeks (NX-4) after nephrectomy compared with their corresponding control animals (C-1, C-2, C-4). Growth cartilage and hypertrophic zone heights were greater in NX-2 (533+/-60 and 264+/-32 microm) than in C-2 (345+/-10 and 131+/-11 microm), with no significant differences in the other groups. This report shows that enlargement of the growth plate and its hypertrophic stratum is greatly, although not exclusively, influenced by the severity and duration of renal insufficiency.
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PMID:Growth plate height of uremic rats is influenced by severity and duration of renal failure. 1467 56

Donor-acceptor (D-A) polymers have been widely studied for their tunable electronic properties, however, it is surprising that systematic studies on the effect of different solvents and electrolytes on their opto-electrochemical, morphological and electrochromic performance have drawn only little attention. In the presented work, nine different D-A polymer films, poly(4,7-di(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)benzo[1,2,5]thiadiazole) (a-i-P1), were electrosynthesised using different polar solvents (PC, MeCN and DCM) and supporting electrolytes (TBAPF6, TBAClO4 and TBABF4). A thorough study of these D-A polymer films using cyclic voltammetry, UV-Vis-NIR spectroscopy, FE-SEM, spectroelectrochemistry and electrochromic techniques has been performed. We found a significant effect of both the supporting electrolytes and solvents on the morphology of polymer films which correlates well with their opto-electronic properties. Films prepared using the TBAClO4/PC system show a smooth morphology with a significantly high coloration efficiency of 264 cm2 C-1 and an optical contrast of 65.3%. Such differences in the optical and electrochemical properties of polymer films were explained by the ion pair formation during polymerisation.
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PMID:Benzothiadiazole bridged EDOT based donor-acceptor polymers with tunable optical, electrochemical, morphological and electrochromic performance: effects of solvents and electrolytes. 3257 23