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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We measured rat brain cortex PO2 (PtO2) with gold microelectrodes (tip diameter 5--10 micron) for up to 2 hours after 16 min of transient global brain ischemia with and without thiopental 90 mg/kg infused iv over 60 min beginning at 5 min postischemia. Seventeen rats were immobilized and mechanically ventilated on 1% halothane in oxygen with continuous monitoring of PtO2, ECG, end-expiratory CO2, rectal temperature, and arterial blood pressure. Global ischemia was induced by trimethaphan hypotension to an MAP of about 50 torr and a neck tourniquet inflated to 1500 torr. Postischemia, nine control rats (11 PtO2 measurements) were untreated and eight rats (8 PtO2 measurements) received thiopental 90 mg/kg. Preischemia, PtO2 values in both groups ranged from less than 5--70 torr with values of greatest frequency between 10 and 15 torr. Postischemia, PtO2 in control rats peaked at 45 +/- 8 (SEM) torr at 20 min. In thiopental treated rats, peak PtO2 was 24 +/- 6 torr at 10 min postischemia. Relative frequency histograms of PtO2 revealed that PtO2 in thiopental treated rats was lower (p less than 0.05) between 15 and 30 min postischemia. The magnitude of the decrease in PtO2 between 105 and 120 min postischemia appeared to correlate directly with the absolute preischemic value (i.e., the higher the preischemic PtO2, the greater the decrease in PtO2 postischemia). These results suggest that thiopental administered in large doses in early postischemia does not improve brain oxygenation secondary to a reduction in brain oxygen consumption. The relevance of the correlation between the magnitude of the fall in PtO2 postischemia and the magnitude of the preischemic value is discussed.
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PMID:Postischemic brain oxygenation with barbiturate therapy in rats. 3 43

Oxprenolol is a beta-adrenergic blocker with intrinsic sympathomimetic activity. Such drugs are not currently available in the United States, although they have the advantage of less negative inotropic effect than the available propranolol. In 18 patients with mild essential hypertension, oxprenolol (9 patients) or propranolol (9 patients) was added to thiazide in random double-blind fashion and continued for 7 wk during which supine heart rate, blood pressure, and noninvasively measured cardiac output (by CO2 rebreathing) were determined weekly. With thiazide dosage constant throughout, maximal dose titration to 386. +/- 52.1 (SEM) mg/day of oxprenolol and 360.0 +/- 45.4 mg/day of propranolol was achieved over the first 5 wk. Blood pressure fell with both (141.8 +/- 4.8/96.0 +/- 2.3 to 128.0 +/- 5.1/87.2 +/- 1 mm Hg on oxprenolol, p less than 0.01; 150.8 +/- 5.5/98.0 +/- 1.7 to 129.9 +/- 5.5/86.8 +/- 3.4 mm Hg on propranolol, p less than 0.01). Cardiac output fell from 6.85 +/- 0.63 to 5.77 +/- 0.45 1/min (p less than 0.01) on oxprenolol, and from 6.79 +/- 0.61 to 5.37 +/- 0.37 1/min (p less than 0.02) on propranolol. Oxpranolol. Oxprenolol reduced heart rate from 76.4 +/- 2.0 to 65.6 +/- 2.1 beats/min (p less than 0.001) and it fell from 82.0 +/- 3.8 to 65.3 +/- 3.7 beats/min (p less than 0.001) with propranolol; the fall in heart rate was less but not significantly so for oxprenolol (-14.2 +/- 1.8% and -19.8 +/- 2.8%, p less than 0.1). Thus oxprenolol is equivalent to propranolol in antihypertensive action; minor hemodynamic differences between the two drugs might reflect intrinsic sympathomimetic activity of oxprenolol. Oxprenolol should be considered as an alternative to propranolol.
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PMID:Hemodynamic effects of oxprenolol and propranolol in hypertension. 38 30

Umbilical PaO2 and PaCO2 were continuously monitored in vivo in acute fetal lamb preparations with a semipermeable membrane connected to a mass spectrometer. The response time of this system (0 to 90% of final value) was 36 sec. In seven pregnant sheep (128--135 days gestation) the maternal inspired mixture was abruptly changed and the following changes in fetal PaO2 and PaCO2 were observed: (1) 100% O2 to room air: PaO2 decreased from 21.5 +/- 0.8 (mean +/- SEM) to 14 +/- 1.1 mm Hg at a rate of 1.63 +/- 0.33 mm Hg/min. Following return to 100% O2 the PaO2 returned to 21 +/- 1.1 mm Hg at a rate of 2.44 +/- 0.4 mm Hg/min. (2) 100% O2 to 12% O2/10% CO2: after 6 min the PaO2 fell from 19.3 +/- 1.3 to 6.3 +/- 0.3 mm Hg at a rate of 4.65 mm Hg/min and the PaCO2 rose from 37 +/- 8 to 70 +/-5 mm Hg. At 100% O2 the PaO2 returned to 19 +/- 1.0 mm Hg at a rate of 11.76 +/- 0.086 mm Hg, the PaCO2 to 39 +/- 7 mm Hg. (3) 100% O2 to 90% O2/10% CO2. The PaO2 and PaCO2 increased by 4.7 and 22 mm Hg, respectively. The changes of fetal PaO2 and PaCO2 occurred after 1 minute of changing in maternal inspired mixture except in the transition from 12% O2/10% CO2 to 100% O2 (34 +/- 12 sec). Following the reinstitution of 100% the fetal PaO2 and PaCO2 returned to their previous values within 4 and 16 min, respectively.
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PMID:The effects of changes of maternal PaO2 and PaCO2 on the fetal PaO2 and PaCO2--in vivo study. 62 13

We studied the arterial blood gas determinations done on the first hospital day in 14 narcotic addicts with bacterial endocarditis (group 1) and six addicts with other medical complications of narcotic addiction (group 2). The arterial oxygen tension (PaO2) was 67.3 +/- 3.3 mm Hg (SEM) in group 1, and 75.0 +/- 6.4 mm Hg in group 2, with no statistically significant difference (P less than .20) between the groups. The arterial CO2 tension (PaCO2), 27.8 +/- 1.7 mm Hg, in group 1 was significantly lower (P less than .005) than that of group 2, 40.1 +/- 3.7 mm Hg. The arterial blood pH, 7.47 +/- 0.01 units, in group 1 was significantly higher (P less than .025) than that of group 2, 7.36 +/- 0.06 pH units. Abnormal blood gas values were found in each of the patients in group 1 with a normal admission chest roentgenogram. Arterial blood gas determinations may be useful in the initial examination of ill narcotic addicts.
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PMID:Bacterial endocarditis in narcotic addicts: analysis of arterial blood gases. 66 29

The mechanical properties of cardiac muscle during ultrasonic irradiation have been studied in vitro. Left anterior papillary muscle from normal rats was suspended in buffered lactated Ringers solution equilibrated with 95% O2, and 5% CO2 and maintained at 20 degrees C. The muscles were stimulated to contract isometrically three times per minute at the length which produced maximum tension. Each muscle was irradiated with a MHz ultrasound at an average power of 2.4 Wcm-2 for a period of 10 min with a 10 min recovery period. Irradiation caused an average increase in temperature of the muscle of 1.7 +/- 0.2 degrees C (mean +/- SEM). Irradiation caused the resting tension (1.46 +/- 0.13g) to decrease by 17.8 +/- 4.7% and the developed tension (3.33 +/- 0.61g) to decrease by 4.1 +/- 0.9%. Since changes in contractile properties have been reported with temperature the bath temperature was raised and changes in contraction observed. When compensated for effects of temperature, the changes in resting tension became - 13.3 +/- 4.1% while the change in developed tension became + 1.6 +/- 2.3%. The change in resting tension is highly significant (p less than 0.05 paired t-test) while the change in developed tension is not. Thus 1 MHz ultrasound at an intensity of 2.4 Wcm-2 appears to affect resting tension of cardiac muscle without affecting the active tension. Since changes in cardiac mechanics of this type have not been described previously the effects of ultrasound appears to be unique.
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PMID:The effects of ultrasound on the mechanical properties of rat cardiac muscle. 67 75

At operation the body temperature of mechanically ventilated infants was initially decreased to 25--22 degrees C with surface cooling and further lowered to 16 degrees C by total body perfusion. During circulatory arrest, averaging 40 min, repair of complex intracardiac deformities was carried out. Rewarming to 36 degrees C was achieved by 35--65 min of total body perfusion. Of 29 infants, 23 under 10 kg survived their correction; normothermic ventilation without added CO2 was given throughout the cooling period. The following measurements were made: gas exchange, lung mechanics, heart rate, arterial pressure, right atrial pressure, cardiac output (Qt), ECG, core and nasopharyngeal temperature, as well as biochemical determinations. During surface cooling O2 consumption (VO2), CO2 production (VCO2), endtidal CO2 (PETCO2) and PaCO2 decreased proportionally and linearly with body temperature. Inspiratory resistance, total compliance, physiological dead space (VD/VT), and the single breath CO2 curve did not reveal disturbed lung function. Mean arterial pressure was 98, 90, and 70 mm Hg and heart rate was 141, 107, and 76 beat/min, at temperature 35, 30, and 25 degrees C, respectively. Cardiac index was 2.2 +/- 0.2 liter/min/m2 (mean +/- SEM, n = 25) 2 hours after surgery. Arterial lactate reached peak values of 4.1 +/- 0.3 mM/liter (n = 17), during rewarming but returned to normal. Respiratory alkalosis caused by hyperventilation during cooling caused no apparent harm. No neurological damage was observed. It is concluded that surface cooling performed with normothermic ventilation under guidance of core temperature, VO2, PETCO2, and VCO2, is a safe method.
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PMID:Cardiorespiratory and metabolic effects of profound hypothermia. 72 92

Given the substantial reserve of normal myocardium, its inability to sustain life in the presence of 30-50% necrosis of the left ventricle (LV) seems a paradox. It is known that dyskinesia of the infarcted area probably plays a dominant role in initiating failure after an infarction. To study this problem, a well defined experimental infarction was produced by cryogenic means in 58 rabbits, and the animals were allowed to recover. Groups of rabbits were killed 4 hours and 1,2,5, or 10 days following infarction. As quickly as possible (within 4 minutes) a sample specimen from the infarcted area was removed from the LV and subjected to a force-elongation test while being bathed in Ringer solution at 37 degrees C equilibrated with 95% O2-5% CO2. The data were interpreted assuming an exponential stress-strain law with constants K and C. Mean values of K of 10.6 +/- 0.94 (SEM) were found for the noninfarcted control group, whereas, rather surprisingly, no significant trend in K over 10 days was found in the infarcted group. Mean values of K +/- SEM for the postinfarction groups were as follows: 4 hours, 9.51 +/- 0.63; 1 day 10.54 +/- 1.13; 2 days, 13.15 +/- 2.28; 5 days, 11.59 +/- 1.36; and over 10 days, 12.93 +/-1.02. The functional implications were estimated with a simple model of the shortening required of the viable muscle during the isovolumic phase. It was found that contractile reserve fell rapidly with increasing infarct size, reaching zero for a 60% infarct when K = 10. With K greater than 100, there was no appreciable reduction in reserve. With a constant infarct size, variation in reserve with the afterload-preload ration was found to be logarithmic.
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PMID:The course of passive elasticity of myocardial tissue following experimental infarction in rabbits and its relation to mechanical dysfunction. 90 16

Maize glucose was used as a natural tracer for studies of metabolism. It is richer in 13C than common vegetables and foods derived from these, and the C02 formed from it is consequently richer in 13C than the CO2 expired by man fed on a diet of common vegetables. The quantitative results, obtained by measurement of delta 13C of the expired CO2 and of VCO2 during the oxidation of an exogenous glucose load (about 100 g) in eight normal subjects over 7 hr, have shown a consumption of 28.64 +/- 1.44 g of glucose (mean +/- SEM), which represents about 30% of the load given. A comparison is made with the results obtained from other methods and the originality and usefulness of this new quantitative procedure is outlined.
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PMID:Quantitative evaluation of the oxidation of an exogenous glucose load using naturally labeled 13C-glucose. 99 39

Neutrophils from bovine milk and blood platelets from dog plasma were washed in PBS, fixed in GA, dehydrated, suspended in a drop on a formvar-coated slide and immediately critical-point-dried in CO2. After coating with Pt-Pd the specimens were examined in an SEM. The same cells were then examined by interferometry (Int) in a light microscope, and the dry mass was determined. It is shown that this preparation method for both types of microscopes (SEM and Int) appears to give adequate results as far as fine surface structure (SEM-appearance) and dry mass determinations (Int) are concerned. The method has the advantage of a more precise characterization of individual particles, than would have been possible, if both methods of microscopy (SEM and Int) had been employed on the same sample, but on different specimens.
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PMID:Preparation of cells from suspensions for correlative scanning electron and interference microscopy. 110 40

The isolated brains of 12 previable human fetuses obtained at 12 to 21 weeks' gestation, were perfused through the interval carotid artery with glucose (3 mM) and/or DL-B-OH-butyrate (DL-BOHB), 4.5 MM, plus tracer quantities of either glucose-6-14C (G6-14C) or beta-OH-butyrate-3-14C (BOHB3-14C). Oxidative metabolism was demonstrated by serial collection of gaseous 14CO2 from the closed perfusion system, and from the recirculating medium. Glucose and BOHB were utilized at physiological rates as indicated (mean plus or minus SEM): G6-14C at 0.10 plus or minus 0.01 mumoles/min g brain (n equal 7) or 17.5 plus or minus 1.9 mumoles/min kg fetus; and BOHB3-14C at 0.16 plus or minus 0.05 mumoles/min g (n equal to 5) or 27.3 plus or minus 7.4 mumoles/min kg. Based on fetal weight, glucose metabolism by brain apparently accounted for about 1/3 of basal glucose utilization in the fetus. On a molar basis BOHB3-14C was taken up at 1.47 times the rate of G6-14C. Both BOHB3-14C and G6 14C were converted to 14CO2. The rate of BOHB3-14C conversion to 14CO2 was equal to its rate of consumption, and exceeded the conversion of glucose to CO2 because 45% of the G6-14C was incorporated into lactate-14C. Accordingly, both substrates support oxidative metabolism by brain; and BOHB is a major potential alternate fuel which can replace glucose early in human development.
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PMID:Oxidation of glucose and D-B-OH-butyrate by the early human fetal brain. 111 94


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