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)

In the present study we used the pH sensitive absorbance of 5(and6)-carboxy-4',5'-dimethylfluorescein to investigate intracellular pH (pHi) regulation in A10 vascular smooth muscle cells: (1) The steady state pHi in A10 cells averaged 7.01 +/- 0.1 (mean +/- SEM, n = 26) at an extracellular pH of 7.4 (28 mM HCO3/5% CO2). (2) Removal of extracellular sodium led to an intracellular acidification of 0.36 +/- 0.07 pH-units (mean +/- SEM, n = 8). (3) pHi-Recovery after an acute intracellular acid load (by means of NH4Cl-prepulse) was reversibly blocked by 1 mM amiloride and was dependent on the presence of sodium. The velocity of pHi recovery increased with increasing sodium concentrations with an apparent Km for external sodium of about 30 mM and a Vmax of about 0.35 pH units/min. These findings are compatible with a Na/H exchanger being responsible for pHi recovery after an acid load. (4) Removal of extracellular chloride induced an intracellular alkalinization of 0.23 +/- 0.03 pH-units (mean +/- SEM, n = 10). The alkalinization was dependent on the presence of extracellular bicarbonate. (5) Removal of chloride during pHi recovery from an alkaline load (imposed by acetate prepulse) stopped and reversed pHi backregulation. Chloride removal had no effect in the absence of bicarbonate or in the presence of 10(-4) M DIDS, suggesting that the effects were mediated by a Cl/HCO3 exchanger. In conclusion we have demonstrated evidence for a Na/H exchanger and a Cl/HCO3 exchanger in A10 vascular smooth muscle cells.
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PMID:Evidence for Na/H exchange and Cl/HCO3 exchange in A10 vascular smooth muscle cells. 317 85

Patterns of VA/Q distribution and their relationship to spirometric indices were studied in 10 patients with acute severe asthma requiring hospitalization (7 women and 3 men 41.0 +/- 5.6 yr of age, mean +/- SEM) on admission and during subsequent recovery. On admission, all patients received the standard therapeutic regimen for our hospital. Spirometry and essentially noninvasive multiple inert gas elimination measurements were obtained serially, approximately once every day, whereas conventional arterial blood gases were determined every 3 days. On admission, all patients showed severe air-flow obstruction (FEV1/FVC% = 34.1 +/- 4.3%) and moderate to severe hypoxemia without CO2 retention (PaO2 = 50.5 +/- 2.6 mm Hg; PaCO2 = 37.1 +/- 2.4 mm Hg; AaPO2 = 53.7 +/- 3.0 mm Hg). Nine of the 10 patients showed bimodal blood flow distributions (dispersion of blood flow distribution, log SD Q = 1.34 +/- 0.11; normal range, 0.3 to 0.6) with only small amounts of shunt (1.09 +/- 0.8%). However, no significant interindividual correlations were observed between maximal expiratory flow rates (FEV1 and FEF25(-75) and log SD Q (r2 = 0.14 and 0.006, respectively). This lack of correlation persisted throughout hospitalization. Despite both clinical and spirometric improvement in all patients, there was simultaneous improvement in VA/Q matching in only one patient. Statistically significant negative correlations between maximal expiratory flow rates and gas exchange did develop toward the end of the study (Weeks 3 and 4 after discharge) when maximal recovery of physiologic changes associated with the acute asthma attack was achieved.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Serial relationships between ventilation-perfusion inequality and spirometry in acute severe asthma requiring hospitalization. 319 3

Changes in the density of eye movement during rapid eye movement (REM) sleep are associated with changes in ventilation and ventilatory response in animals. Recent data in patients with chronic obstructive pulmonary disease suggest that periods of frequent eye movements may be associated with hypoxemia during REM sleep. We have therefore investigated the association between eye movements and ventilation and ventilatory pattern in 10 normal men. Expired ventilation was measured using a pneumotachograph attached to a valved face mask with a dead space of 50 ml and incorporating a peripheral CO2 leak detector. Ventilation was reduced (p less than 0.02) in all stages of sleep compared with that during wakefulness, with no difference between the level of ventilation in each sleep stage (awake, 7.18 +/- 0.43 SEM; Stage 2, 6.47 +/- 0.43; Stage 3/4, 6.45 +/- 0.52; REM sleep, 6.55 +/- 0.47 L/min). During REM sleep, eye movements (EMs) were associated with rapid shallow breathing. Dividing REM into 20-s epochs with or without EMs, EMs were associated with a raised breathing frequency (no EMs, 14.4 +/- 0.4 breaths/min; EMs, 15.8 +/- 0.5 breaths/min; p = 0.01), reduced tidal volume (0.49 +/- 0.03 L; 0.41 +/- 0.03 L; p less than 0.01), and reduced minute ventilation (6.87 +/- 0.45 L; 6.27 +/- 0.51 L; p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Breathing pattern and eye movement density during REM sleep in humans. 320 62

We have compared the effects of critical point-drying (CPD) and freeze-drying (FD) on the morphology of Triton-resistant cytoskeletons and microtubules by scanning (SEM) and transmission electron microscopy (TEM). In general, cytoskeletons attached to Formvar films suffer less structural damage than cells or cytoskeletons attached to glass, because the Formvar film absorbs some of the stress associated with shrinkage during drying. However, as seen in stereo-pair electron micrographs, the three-dimensional structure of cytoskeletons prepared by FD is better preserved and shows fewer artefacts than those prepared by CPD. CPD specimens are flatter, often have a concave and apparently collapsed nuclear matrix and show large cracks both in the perinuclear zone and through the cytoskeleton. At least some of the damage appears to be due to residual water in the CO2 used as the substitution fluid, because cytoskeletons dried with a water filter attached to the CPD apparatus show substantially less damage than those dried without the filter. Freeze-dried cytoskeletons consist mostly of unbroken, smooth filaments and have no perinuclear open space. Comparison of the effects of drying on the diameters of in vitro polymerized microtubules showed that the diameter of microtubules is reduced after drying, but that FD causes significantly less shrinkage than CPD. Addition of 0.2% tannic acid to the glutaraldehyde fixative significantly reduces the shrinkage of CPD microtubules, but has no effect on FD microtubules. The observations on microtubules support the hypothesis that drying-induced shrinkage is the result of both pressure and solvent evaporation and they indicate that tannic acid stabilizes samples against the former but not the latter.
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PMID:Comparison of the effects of critical point-drying and freeze-drying on cytoskeletons and microtubules. 321 82

To determine the safety, efficacy, and the ventilatory responses to carbon dioxide (CO2) of mini-dose intrathecal morphine, 33 healthy women who underwent cesarean section with spinal anesthesia using 0.75% bupivacaine in 8.25% dextrose were studied. Patients were randomly assigned to receive, in a double-blind fashion, either morphine 0.25 mg (group I, n = 11), morphine 0.1 mg (group II, n = 10), or saline (group III, placebo group, n = 12) in 0.5 ml volume mixed with the bupivacaine. In both groups I and II excellent postoperative analgesia with long duration was obtained (27.7 +/- 4.0 and 18.6 +/- 0.9 hours, respectively, X +/- SEM). All patients in group III required an analgesic (8 mg subcutaneous morphine) within 3 hours of spinal anesthesia. Seven patients in group I and four patients in group II developed mild pruritus that did not require treatment. Ventilatory responses to CO2 showed no evidence of depression attributable to either the 0.25 or 0.1 mg of morphine, but significant depression of the CO2 responses was observed in group III patients after administration of subcutaneous morphine. It is concluded that a dose as low as 0.1 mg of intrathecal morphine gives excellent analgesia with minimal to no side effects and that subcutaneous morphine is associated with marked depression of the ventilatory variables.
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PMID:Mini-dose intrathecal morphine for the relief of post-cesarean section pain: safety, efficacy, and ventilatory responses to carbon dioxide. 327 78

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 accuracy of transcutaneous CO2 monitoring with the Kontron CO2 sensor was studied during compression to 41 bar and subsequent decompression. The PCO2 was stable and accurate during the test of the sensor in the pressure chamber, although an increase of 0.1-0.2 kPa during compression was found. The function of the transcutaneous sensor was tested in rats at 1 bar for the correlation between transcutaneous PCO2 (PtcCO2) and arterial PCO2 (PaCO2). The correlation coefficient between PtcCO2 and PaCO2 in the rat was found to be 0.93. The time difference between the 90% transcutaneous and 90% arterial response time was 4.6 +/- 0.6 min (mean +/- SEM). Finally, the use of the sensor in rats ventilated at constant minute volume during compression to 41 bar was examined. An increase in PtcCO2 of 0.2-0.4 kPa was found. The present results of transcutaneous PCO2 measurements indicate that this method may be useful in hyperbaric research and treatment.
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PMID:Transcutaneous measurement of PCO2 at high ambient pressure (41 bar). 336 95

Previous studies have suggested that the apparent dissociation constant of blood carbonic acid (pK') may actually vary in acutely ill patients. We prospectively compared the pK' of healthy control subjects to that of patients undergoing cardiopulmonary resuscitation (CPR). Arterial blood obtained from 20 patients undergoing CPR and from 30 healthy volunteers was analyzed for Na+, pH, PCO2, and total CO2 content (tCO2). pK' was calculated from this data, using the Henderson-Hasselbalch equation. Total CO2 was then calculated in the CPR patients, using this equation and the control pK'. Mean pK' was 6.109 +/- 0.004 (SEM) for the control group and 6.123 +/- 0.007 for the CPR group (p = NS). In the CPR group, calculated tCO2 was not significantly different from measured from tCO2, and the correlation between calculated and measured tCO2 was 0.99. In patients undergoing CPR, pK' does not differ significantly from normal, and tCO2 can be accurately estimated with the Henderson-Hasselbalch equation.
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PMID:Constancy of blood carbonic acid pK' in patients during cardiopulmonary resuscitation. 337 Nov 2

The effects of a continuous epidural administration of fentanyl on pain and on ventilation were studied in eight patients scheduled for orthopedic surgery of the knee. In each subject, epidural fentanyl was given by a bolus dose of 1 microgram.kg-1, followed by a continuous infusion of 1 microgram.kg-1.h-1 over 18 hours. Ventilatory measurements were performed during quiet breathing and during CO2 stimulation tests before surgery. After surgery measurements were made before epidural administration of fentanyl; 1, 2, 5, 18 hours after the start of epidural fentanyl infusion; and 6 hours after its discontinuation. Adequate pain relief was achieved in all patients during fentanyl administration. No significant change in ventilation was noted during quiet breathing. The slope of the ventilatory response to CO2 (VE/PaCO2) decreased significantly from 1.46 +/- 0.2 to 0.75 +/- 0.1 L.min-1.mm Hg-1 (mean +/- SEM; P less than 0.05) one hour after the onset of fentanyl administration, and remained stable throughout the infusion. Eighteen hours after the onset of epidural fentanyl infusion, VE/PaCO2 was still 0.76 +/- 0.14 L.min-1.mm Hg-1. At the end of fentanyl administration, plasma fentanyl levels measured in six patients had progressively increased from 0.42 +/- 0.02 ng.ml one hour after the onset of the infusion to 1.54 +/- 0.19 ng.ml at the end of the infusion. These results suggest that a continuous epidural administration of fentanyl is a technique of analgesia that can provide adequate pain relief but which is associated with ventilatory depression. However, with the doses used in this study, the ventilatory depression remained moderate and of no demonstrable clinical consequence.
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PMID:Ventilatory effects of continuous epidural infusion of fentanyl. 342 1

A method for measurement of human basal and stimulated gastric bicarbonate secretion was developed in the present investigation. The mechanisms involved in the regulation of basal, vagus nerve stimulated as well as fundic distension induced bicarbonate secretion were studied. The investigations were performed in healthy subjects and duodenal ulcer patients, the latter group before and/or after a proximal gastric vagotomy operation. Healthy subjects as well as ulcer patients were premedicated with a histamine H2-receptor antagonist and gastric bicarbonate secretion was determined by use of a gastric perfusion system in combination with computerized continuous recordings of pH and PCO2. The contribution of alkaline saliva to the measured gastric bicarbonate secretion was minimized by continuous salivary suction and correction was made for swallowed saliva by measurement of amylase in the gastric aspirate. A high rate of gastric perfusion facilitated the identification of alkaline duodenogastric reflux and also eliminated its influence on the measurement of gastric bicarbonate secretion. Validation of the measuring system by instillation of small amounts of bicarbonate showed a satisfactory correlation between added and recovered bicarbonate in the range of bicarbonate determinations usually recorded. Decreasing intragastric pH to between 3 and 4 converted all secreted bicarbonate into CO2, but did not affect the measured value of bicarbonate secretion. Vagal stimulation accomplished by sham feeding increased gastric bicarbonate secretion in sixteen healthy subjects from 410 +/- 39 mumol/h to 692 +/- 67 mumol/h (mean +/- SEM, p less than 0.001). This response was independent of intragastric pH in the range of 2 to 7. The muscarinic receptor antagonist, benzilonium bromide, almost abolished the sham feeding response while indomethacin left it nearly unchanged. Nine duodenal ulcer patients had identical basal and vagally stimulated bicarbonate output as healthy subjects. Two months after proximal gastric vagotomy, the basal bicarbonate secretion was significantly increased, whereas the output in response to sham feeding was unaltered. In the early postoperative period, anticholinergics reduced the enhanced basal bicarbonate secretion to a preoperative level. In six healthy subjects, graded fundic distension with a balloon to volumes of 150 ml, 300 ml and 600 ml, each distension period lasting 60 minutes, increased the bicarbonate secretion by 46% (p less than 0.05), 28% (NS) and 84% (p less than 0.05), respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Studies on gastric bicarbonate secretion in man. 347 32


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