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

Lactate elimination was studied in twenty-six healthy volunteers during primed constant lactate infusion or multiple lactate injection tests, at blood lactate concentrations of 1-8 mmol-1. Although lactate elimination fitted a single exponential curve over a 30 min period, a significant correlation between the rate removal constant (KL) and the peak blood lactate concentration (Lphi) was demonstrated: loge KL = -2.43-0.132 Lphi (P = 0.003, r = 0.63, n = 20) This suggests that lactate removal does not follow first order kinetics over a wide concentration range but becomes saturated at relatively low blood lactate concentrations. Estimates of the lactate distribution volume did not differ significantly at different dosage levels, but remained in the range 270-300 ml kg-1. Skeletal muscle uptake accounted for about 26% of the infused lactate load. Seven patients with well-compensated hepatic cirrhosis were compared with a group of six control subjects during primed constant infusion tests. Fasting and steady state blood lactate concentrations achieved were similar in both groups. A significant prolongation in lactate half-life was demonstrated in the cirrhotics (18.8 +/- 1.4 min (mean +/- SEM) compared to 14.7 +/- 2.2 min; P less than 0.02). Since peripheral uptake of lactate in the forearm was similar in the two groups, this suggests that hepatic lactate uptake was impaired, due either to hepatocyte dysfunction or portal diversion.
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PMID:Lactate elimination in man: effects of lactate concentration and hepatic dysfunction. 11 34

Large White gilts, 9 to 18 months old, that had exhibited at least two natural oestrous cycles were divided into three groups (phases): unmated pre-ovulatory, unmated post-ovulatory and mated post-ovulatory (n = 16, 20 and 18). Oviductal luminal fluid samples were collected under anaesthesia by micropipette from the ampulla and ampullary-isthmic junction and analysed by an ultramicrofluorometric technique. Glucose concentrations (mmol 1(-1), means combining regions; mean +/- SEM) were significantly higher in blood plasma than in oviductal fluid (4.56 +/- 0.20 versus 0.59 +/- 0.16; P < 0.0001; n = 27), whereas lactate was higher in the oviduct (5.71 +/- 0.53 versus 2.48 +/- 0.24; P < 0.0001; n = 27). No significant differences were found between the ampulla and the ampullary-isthmic junction. However, the concentration of glucose was significantly higher (P < 0.05) in the ampulla of the pre-ovulatory group (0.97 +/- 0.20; n = 13) compared with the mated group (0.25 +/- 0.05; n = 14) and its concentration in the ampullary-isthmic junction in the pre-ovulatory group (1.65 +/- 0.63; n = 13) was significantly greater (P < 0.05) than in the post-ovulatory (0.43 +/- 0.11; n = 11) or mated groups (0.17 +/- 0.02; n = 14). Lactate in the ampulla of mated animals was higher than in the pre-ovulatory group (6.83 +/- 0.70 versus 3.86 +/- 0.38; P < 0.05; n = 15 and 13), but neither was significantly different from the post-ovulatory group. Furthermore, no change was seen at the ampullary-isthmic junction in lactate concentration with phase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Concentrations of energy substrates in oviductal fluid and blood plasma of pigs during the peri-ovulatory period. 133 49

To evaluate the influence of cow breed and number of fetuses on uterine and umbilical blood flows and nutrient fluxes or uterine tissues from gravid cows, surgery was performed on Charolais or Hereford cows with single or twin fetuses at 177 +/- .2 d (mean +/- SEM) after mating. Indwelling catheters were placed in a fetal femoral artery and vein, in an umbilical vein of each fetus, and in a uterine artery and vein of each gravid horn. Deuterium oxide (D2O) was infused into a fetal femoral vein at 183 +/- .3 and 190 +/- .5 d after mating to estimate uterine and umbilical blood flows (liters/minute). Blood oxygen and plasma glucose and lactate concentrations were determined and uterine arterio-venous (A-V) and umbilical venous-fetal arterial (v-a) differences and net uterine and fetal uptakes were calculated. Net utilization by the uteroplacenta was calculated as the difference between uterine and fetal net uptakes. Uterine blood flows were lower (P less than .01) in Hereford (4.80 +/- .28) than in Charolais (7.07 +/- .33) and lower (P less than .01) per fetus in cows with twin fetuses (5.22 +/- .34) than in cows with a single (6.65 +/- .28) fetus. Umbilical blood flows were greater for single than for twin fetuses. Fetal oxygen and glucose net uptakes averaged 57 and 12%, respectively, of net uteroplacental utilization. Lactate was released from uteroplacental tissues to fetal (42%) and maternal circulations (58%). Fetal oxygen uptakes tended to be less for twin fetuses (P = .08) than for a single fetus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Uterine and umbilical blood flows and net nutrient uptake by fetuses and uteroplacental tissues of cows gravid with either single or twin fetuses. 154 4

To evaluate the ontogeny of neonatal glucose homeostasis, glucose production and lactate production have been measured in nine prematurely born appropriate for gestational age neonates [birth weight 1985 +/- 100 g, (SEM) gestational age 33.6 +/- 0.7 weeks] and five full term appropriate for gestational age neonates [birth weight 3254 +/- 111 g, gestational age 40.8 +/- 0.4 wks] and compared to six non pregnant, nondiabetic adults [weight of 57.7 +/- 2.2 kg, age 32 +/- 2 years]. Ra glucose (preterm) averaged 27.7 +/- 2.8 mumol.kg-1 min-1 (5.0 +/- 0.5 mg.kg-1 min-1) and Ra glucose (term) averaged 28.9 +/- 3.9 mumol.kg-1 min-1 (5.2 +/- 0.7 mg.kg-1 min-1); both were higher than the Ra glucose of the adult controls (16.1 +/- 2.8 mumol.kg-1 min-1 (2.9 +/- 0.5 mg.kg-1 min-1) (P less than 0.05 vs preterm and P less than 0.05 vs. term). Ra lactate (preterm) averaged 100 +/- 11.9 mumol.kg-1 min-1 (9.1 +/- 1.1 mg.kg-1 min-1) and Ra lactate (term) average 77.2 +/- 13.0 mumol.kg-1 min-1 (7.1 +/- 1.2 mg.kg-1 min-1); both were higher than the Ra lactate of the adult controls 35.9 +/- 6.5 mumol.kg-1 min-1 (3.3 +/- 0.6 mg.kg-1 min-1) (P less than 0.01 vs preterm and P less than 0.05 vs. term). The potential for gluconeogenesis from lactate was estimated by determining the ratio of [Ra Lactate/Ra Glucose]. The [Ra Lactate/Ra Glucose] (preterm) (187 +/- 12 (x10(-2)) was similar to that of the [Ra Lactate/Ra Glucose] (term) (136 +/- 16) (x10(-2)).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucose and lactate kinetics in the neonate. 182 15

The efficacy of funnel-freezing of rat brain to inactivate metabolic processes and preserve in vivo tissue glucose concentration was validated by comparing the results obtained by funnel-freezing with those obtained with freeze-blowing of brain. The arterial plasma glucose level was clamped at 9 mM in halothane-anesthetized rats to produce identical glucose levels in brain tissue prior to freeze fixation. In funnel-frozen and freeze-blown brains, tissue glucose concentrations were 2.47 +/- 0.05 and 2.47 +/- 0.06 mumol/g (means +/- SEM), respectively. Lactate levels in funnel-frozen brains were slightly but significantly higher than those in freeze-blown brains, i.e., 1.56 +/- 0.05 mumol/g versus 1.30 +/- 0.05 mumol/g (means +/- SEM; p less than 0.05). Regional analysis in funnel-frozen brains revealed that glucose concentrations in superficial and basal brain areas remained approximately equal at 2.30 +/- 0.1 mumol/g and 2.31 +/- 0.09 mumol/g (means +/- SEM), respectively. Our findings indicate that in the anesthetized rat, funnel-freezing of brain is suitable for the measurement of regional in vivo glucose concentrations.
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PMID:Comparison of freeze-blowing and funnel-freezing of rat brain for the measurement of cerebral glucose concentration in vivo. 201 60

Decreased hepatic clearance of exogenous sodium lactate has previously been demonstrated in patients with hepatic dysfunction. The purpose of this study was to obtain a more precise understanding of the rate of metabolic normalization or decrease of endogenously produced lactate in patients with hepatic cirrhosis. The differential kinetics of lactate metabolism are of clinical interest. Male volunteer patients with hepatic cirrhosis (n = 7), who had survived acute hospitalization, were compared to healthy age-matched males with normal liver function (n = 7). After arterial cannulation, bicycle ergometry was performed at a workload of 25 watts (W); the load was increased by increments of 25 W at 2-min intervals to maximum aerobic capacity. Lactate was measured in arterial blood before, at 4-min intervals during, and on a minimum of 11 occasions in the 30 to 70 min after exercise. The time interval during which lactate declined linearly to half its maximal concentration (Lt50) was graphically computed. The Lt50 was 34.8 +/- 4.5 min (mean +/- SEM) in the experimental group and 14.1 +/- 1.3 min in the control subjects (p less than .005). Lactate disappears from the bloodstream almost three times more slowly in patients with hepatic cirrhosis. The implication for interpretation of changes in lactate during circulatory shock in the presence of liver dysfunction is addressed.
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PMID:Prolongation of the half-life of lactate after maximal exercise in patients with hepatic dysfunction. 276 57

Knoop Hardness and pin-and-disc-wear measurements were made on a commercial silver-sintered glass-ionomer cement. The objective was to determine whether the incorporation of a bonded-metal-to-glass filler would enhance durability as determined by the above measurements. As with the previous work on conventional (non-metalized) glass-ionomer cements, the specimens were preconditioned at 37 degrees C in air, water, 0.02 mol/L lactic acid (pH 2.67), and heptane. The influence of these media on the microhardness of the silver-sintered material was about the same as that on the conventional materials. Storing in air produced dehydration, which increased the hardness considerably. Heptane storage increased the hardness less, but this increase is attributed to continued curing during storage. After storage in water, the hardness was essentially unchanged; the influence of increased cure is believed to be offset by softening or plasticization from water uptake. Lactic acid produced a decrease in hardness from chemical dissolution as seen from the SEM observations. In most cases, in particular for the air-stored specimens, the wear resistance was enhanced markedly over that of the conventional materials evaluated previously. The exception was the lactic acid-stored specimens for which little, or no, improvement was observed during early periods of wear. The incorporation of silver appeared to provide lubrication, thus reducing wear. However, catastrophic failure from brittle fracture was still a problem, but its occurrence was less frequent.
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PMID:Wear and microhardness of a silver-sintered glass-ionomer cement. 296 19

The measurement of arterial blood lactate concentration for the purpose of estimating the severity and prognosis of acute perfusion failure is suspect because of theoretical errors due to systemic "lactate washout" immediately following restoration of perfusion. If arterial lactate concentrations continue to increase following resuscitation, the assumption that increasing lactate concentrations indicate progression of anaerobiosis due to perfusion failure would be invalidated. Lactate washout was therefore investigated in a porcine model of cardiac arrest due to electromechanical dissociation. Cardiopulmonary resuscitation was initiated and maintained for intervals of 30 minutes or until spontaneous circulation was restored. In 25 trials on 14 successfully resuscitated animals, the arterial blood lactate concentration decreased within four minutes after resuscitation from cardiac arrest. In 24 animals in whom resuscitation efforts failed, arterial lactate concentrations increased throughout the observation period. Lactate washout occurred during an interval of only 2.6 +/- 0.3 minutes (mean +/- SEM). These results indicate that lactate measurements are not invalidated because of a washout phenomenon under the extreme conditions of cardiac arrest.
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PMID:'Lactate washout' following circulatory arrest. 339 92

In vivo substrate utilization has not been described for the maturing fetal lung. We, therefore, studied pulmonary delivery and use of major fetal substrates in six chronically catheterized fetal lambs over 119-141 days gestation. Oxygen, glucose, lactate, and alpha-amino nitrogen concentrations were measured in the pulmonary artery and pulmonary vein whereas lung blood flow was determined using labeled microspheres. We found that lung oxygen availability and use increased near term. Oxygen delivery averaged 4960 +/- 480 (SEM) microliters/min and rose with fetal age (p less than 0.05); uptake averaged 708 +/- 111 microliters/min and increased 93% near term (p less than 0.05). In contrast, glucose availability and use fell with gestation. Pulmonary artery glucose decreased with time (p less than 0.001), with a mean drop of 5.05 +/- 1.71 mg/dl in individual animals (p less than 0.05). Average glucose uptake was 844 +/- 225 micrograms/min and fell near term (p less than 0.05). Lactate was produced by the lung at a mean rate of 534 +/- 176 micrograms/min; this did not change with gestation. Lung amino nitrogen availability increased with fetal age. Pulmonary artery amino nitrogen rose by 1.35 mg/dl, or 43% (p less than 0.001) and lung delivery of amino nitrogen increased (p less than 0.05). The mean pulmonary glucose/O2 ratio was 1.48 +/- 0.26 and decreased with gestation (p less than 0.05), being less than 1.0 near term. The glucose-lactate/O2 ratio was 0.67 +/- 0.26, implying that 30% of lung oxidative metabolism is still unaccounted for. The alterations in delivery of substrates to the lung which were identified may serve as signals for pulmonary maturation, inducing the changes in lung metabolism that were found near term.
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PMID:Substrate utilization by the fetal sheep lung during the last trimester. 339 94

The substrate and oxygen uptake by some organs in intact developing animals has been described, however, the kidney has not been studied. To examine substrate and oxygen uptake by the kidney, we implanted polyvinyl catheters into the renal vein, descending aorta, inferior vena cava, and urinary bladder of 11 fetal sheep (120-125 days gestation) and eight newborn lambs (1 day postnatal). Four days after surgery, blood samples were obtained simultaneously from the renal vein, aorta, and inferior vena cava for determination of oxygen content and saturation, and glucose and lactate concentrations. Renal blood flow was determined by the radionuclide-labeled microsphere method in the fetal lambs and by measuring 14C-inulin clearance in the newborn lambs. The fetal and newborn kidneys consumed oxygen at rates of 123 +/- 16 and 785 +/- 79 mumol/min/100 g kidney weight (mean +/- SEM), respectively. The increase in oxygen consumption from the fetal to the newborn period was accompanied by an increase in oxygen extraction from 25-35%, a large increase in oxygen delivery from 418 +/- 38 to 2231 +/- 127 mumol/min/100 g, and marked increases in glomerular filtration rate and sodium reabsorption (measured in six additional fetal sheep and the eight newborn lambs). This suggests that the postnatal increase in renal tubular activity is associated with an increase in oxygen consumption. Lactate was taken up by both fetal and newborn kidneys, and in nine of the 11 fetuses and in four of the eight newborns, there was net glucose release from the kidney.
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PMID:Renal metabolism in fetal and newborn sheep. 402 71


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