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PubMed1981

Voluntary exercise during pregnancy and lactation and its effect on lactational performance in mice.

The amount of voluntary exercise during pregnancy and lactation and its effect on the lactational performance in mice were investigated. Female mice were housed in exercise cages with treadwheels during periods of growth, pregnancy and lactation and the amounts of exercise were measured. It was observed that growing female mice exercised voluntarily at a level of approximately 5,000 rotations (diameter of treadwheel; 13.5 cm) per day during the 4-week growth period. After conception, the amount of exercise gradually decreased and in late pregnancy running activity decreased markedly. Throughout the lactational period dams exercised lightly. As indices of lactational performance, the body weights of pups nursed in litters of 8, milk yield and cellular development of abdominal-inguinal mammary glands were examined. There were no significant differences in the final body weights of pups, milk yield per day or development of mammary glands between exercise and non-exercise groups.

Adipose Tissue↗
PubMed1992

Calcium, magnesium mass transfer and lactate balance study in CAPD patients with reduced calcium/magnesium and high lactate dialysis fluid.

We studied calcium (Ca), magnesium (Mg) mass transfer (MT) in 10 and lactate balance in 5 CAPD patients using standard dialysis solution [(ST) (Ca 1.75 mmol/l; Mg 0.75 mmol/l; lactate 35 mmol/l)] and with reduced Ca/Mg, high lactate solution [(LC) (1.25 mmol/l; 0.25 mmol/l; 40 mmol/l respectively)]. Exchanges were performed with 1.36% and 3.86% glucose solutions. MT was calculated as mmol/exchange. Ca MT was +0.96 and +0.39 with ST 1.36% and 3.86% glucose respectively. Serum ionised Ca (iCa++) levels were less than fluid Ca during these exchanges. With LC 1.36% glucose it was -0.66 when ICa++ was more than dialysate Ca, but +0.66 when iCa++ was less than dialysate Ca. Ca MT was negative with LC 3.86% glucose irrespective of iCa++ levels. All patients were hypermagnesaemic (mean 1.24 mmol/l. Mg MT was +0.21 and -0.04 with ST 1.36% and 3.86% glucose respectively and -0.62 and -1.13 with LC 1.36% and 3.86% glucose respectively. The difference between mean lactate gain and bicarbonate loss was less (-0.4) during exchange with LC 1.36% glucose. Mean plasma TCo2 and plasma pH did not differ between ST and LC solutions. We conclude that reduced Ca/Mg, high lactate solutions should reduce hypercalcaemia/magnesaemia and maintain a better acid base balance in CAPD patients who may require Ca/Mg containing phosphate binders.

Adult↗
PubMed1977

[The disease entity of lactate acidosis. 3. Lactate as a metabolic product].

High blood lactate concentrations can be achieved by means of intravenous bicarbonate infusion. Metabolic production of lactic acid in this case is a compensation mechanism for the alcalosis induced by bicarbonate. This metabolic condition is called lactate alcalosis. The meaning and the diagnostic value of the lactate/pyruvate quotient and of excess lactate are discussed. A metabolic increase of the lactate/pyruvate quotient (normal values being 10-20) can be attained during the intravenous application of polyalcohols (like xylitol or sorbitol) or of ethanol. In these cases blood lactate concentration remains approximately normal. The alterations are due to the metabolism of the alcohols predominantly in the cytoplasmic compartment of the hepatocytes. The anion-gap is caused by the fact that the anions are considered only in part. However, the diagnostic value of the anion-gap is only minimum. An increase in the anion-gap with a simultaneous decrease in blood-pH is not significant for a lactate acidosis.

Acidosis↗
PubMed1988

Pathogenicity of two strains of Streptococcus uberis infused into lactating and non-lactating bovine mammary glands.

Two strains of Streptococcus uberis, one (0140J) resistant to killing by purified bovine polymorphonuclear leucocytes suspended in milk and the other (EF20) readily killed by polymorphonuclear leucocytes were each infused into a mammary quarter of 18 lactating and 10 pregnant non-lactating cows. In the lactating cows 0140J produced clinical disease in 16 of 18 quarters whereas EF20 produced clinical disease in only two of 18 quarters. With the exception of three cows exposed to EF20, the quarters which resisted infection did so without apparent inflammatory reaction. In non-lactating cows both organisms produced clinical disease in six of 10 quarters. Two cows apart, a non-lactating udder was either resistant or sensitive to both organisms.

Animals↗
PubMed1981

[Changes in the nutritional status of the lactating women during exclusive lactation].

In order to evaluate the influence of breast feeding upon selected nutritional parameters of lactating women, several anthropometric and biochemical measurements were performed during the interval between 40 and 180 postpartum days in 54 women in full and satisfactory nursing. Only one significant change was detected in measurements done for nutritional assessment: loss of body weight. No changes were detected in hemoglobin levels or in serum protein and albumin. There was high variability in body weight changes with a mean loss of 1.5 kg due especially to a loss in fat body mass and, in a lesser proportion, to loss in lean body mass. The mean food intake did not change during the observation period. The mean caloric intake was 2,771 cal/day at the beginning and 2,737 cal/day in the end of the study. A significant correlation was established between the individual energetic intake and the body weight changes of lactating women. The allowance of 2,750 cal/day suggested by FAO/WHO for lactating women seems adequate for the health of women in a normal nutritional condition, but apparently insufficient to overcome undernutrition in women who initiate lactation with this condition. In spite of the small nutritional impact observed, our results support the need for food supplementation programs destined to lactating women, with special orientation to undernourished women of low socioeconomic level.

Adolescent↗
PubMed1976

[A new method for rapid determination of blood L-lactate using an enzymatic lactate sensor (author's transl)].

We determined the lactate concentration in 112 samples of arterial blood, simultaneously by two-different technic: 1) The usual enzymatic technic (plasmatic and intracellular lactates). 2) A new technic using an enzymatic lactate sensor ("lactate analyzer 5400") which measures the plasmatic lactates only. The data obtained with the two technics were very similar (r = 0,982). The small volume of blood used and the handiness and rapidity of the new procedure are to be noted.

Autoanalysis↗
PubMed1996

[Effects of lactation and lifestyles including food intake on bone density of lactating women].

Ultrasonic bone densities were measured in 131 lactating women, aged 21 to 42 years, at 6-590 days postpartum. STIFFNESS Calculated from the combined value of speed of sound and broadband ultrasound attenuation at the calcaneus was used as an index of bone density. The relationships of STIFFNESS with period of lactation, current and past consumption of cow's milk, various food intake frequency, history of participating in sports, daily physical activity, using calcium drugs and sun exposure were examined using stepwise multiple regression analysis, including age and weight as independent variables. 1) The mean (SD) of STIFFNESS was 79.8 (11.9). Thirty-three women (25% of subjects) showed STIFFNESS less than 70. 2) Period of lactation showed a significant negative effect on STIFFNESS (p < 0.05). However, no such effect appeared for women with cow's milk intake of less than 100 ml per day. This result suggests a protection of calcium levels in bone. 3) Current daily cow's milk intake showed significant positive effect on STIFFNESS (p < 0.05). For women lactating less than 150 days, this relation between cow's milk intake and STIFFNESS was clear (r = 0.44, p < 0.01). 4) Significant relation between STIFFNESS and food intake frequencies was found in milk and milk products only among various foods. This result indicates that cow's milk and milk products are important sources of calcium during lactation.

Adult↗
PubMed1983

Changes in circulating plasma levels of cortisol in lactating and non-lactating dairy cattle during the estrous cycle.

Plasma cortisol levels were determined by radioimmunoassay for five lactating cows and five open heifers from blood samples collected daily during the course of a complete estrous cycle. Each animal was fitted with an indwelling jugular catheter to minimize stress from bleeding. Mean plasma cortisol levels were 5.67 ng/ml for the lactating cows and 5.87 ng/ml for the open heifers. Mean values for individuals ranged from 3.79 ng/ml to 6.94 ng/ml in the lactating group, and 3.37 ng/ml to 11.69 ng/ml in the open group. These differences, both between and within groups, were not significant. Mean cortisol values during the estrous cycle ranged from 2.26+/-0.93 ng/ml on day one to 9.49+/-2.11 ng/ml on day six for the lactating group, and 2.74+/-0.52 ng/ml on day six to 14.66+/-10.78 ng/ml on day twelve for the open group. Group by day interactions were not significant. Attempts to correlate plasma cortisol with lactation or day of estrus were not significant.

Journal Article↗
PubMed1998

Continuous measurement of subcutaneous lactate concentration during exercise by combining open-flow microperfusion and thin-film lactate sensors.

The present study was carried out to investigate in vivo in healthy humans the method of open-flow microperfusion for monitoring of the subcutaneous (s.c.) lactate concentration during rest and cycle ergometer exercise. Using open-flow microperfusion, a perforated double lumen catheter with an inflow and an outflow connection is inserted into the s.c. adipose tissue and perfused with a sterile, isotonic, ionfree fluid. Due to the low flow rate, the fluid partially equilibrates with the surrounding tissue. The equilibrated perfusate passes a sensor flow chamber where the substance of interest and the rate of recovery (i.e. the ratio of sampled concentration to interstitial concentration) are continuously monitored. Within this study, the method was evaluated in four healthy volunteers during cycle ergometer exercise. The relative increase of the lactate concentration was approximately a third in the s.c. tissue compared to the capillary blood and the peak time was delayed on average by 10 min. The correlation coefficient between blood and s.c. tissue lactate concentration ranged from r = 0.41 to r = 0.90 (n = 29) in the individual experiments. The combination of open-flow microperfusion and lactate and conductivity sensors enables on-line monitoring of the s.c. lactate concentration without in vivo calibration during steady-state and cycle ergometer exercise.

Adipose Tissue↗
PubMed1998

In vivo voltammetric detection of rat brain lactate with carbon fiber microelectrodes coated with lactate oxidase.

To allow rat brain lactate measurement in vivo, a specific sensor based on a carbon fiber (phi = 30 microns) microelectrode coated with lactate oxidase was prepared. Combined with the differential normal pulse voltammetry measurement method, such a sensor, with a sensitivity of 9.15 +/- 0.91 mA.M-1.cm-2, provided a lactate linear response in concentrations ranging from 0.1 to 2.0 mM. The measurements performed appeared to be essentially insensitive to usual interference caused by the electroactive compounds present in the brain (ascorbic acid and peptides). In vivo detection performed in the cortex of the anesthetized rat led to the determination of a lactate concentration of 0.41 +/- 0.02 mM. Moreover, to validate the results obtained in vivo, an ex vivo determination of the lactate level was also performed in samples of brain tissue, plasma, and cerebrospinal fluid, using both voltammetry and a clinical analyzer with colorimetric-based detection. A good correlation was observed between the sets of data established by both methods.

Animals↗
PubMed1998

The validity of the lactate minimum test for determination of the maximal lactate steady state.

PURPOSE: The purpose of this study was to investigate the validity of the lactate minimum test ([Lac-]BMIN) in the determination of the velocity at the maximal lactate steady state (V-MLSS), and to identify those physiological factors most closely associated with 8-km running performance. METHODS: Thirteen trained male runners (VO2max range 53-67 mL.kg-1.min-1) took part in an 8-km simulated race on flat roads and completed a comprehensive battery of laboratory tests. RESULTS: Performance velocity was most strongly correlated with the estimated running velocity at VO2max (r = 0.93) and with V-MLSS (r = 0.92) and velocity at lactate threshold (V-Tlac) (r= 0.93). The running velocity at the ventilatory threshold (V-Tvent) (r = 0.81) and the [Lac-]BMIN (r = 0.83) also produced good correlations with performance velocity. Performance running velocity (mean +/- SEM 16.0 +/- 0.3 km.h-1) was not significantly different from V-MLSS (15.7 +/- 0.3 km.h-1). The running velocity at [Lac-]BMIN (14.9 +/- 0.2 km.h-1) was not significantly different from the V-Tlac (15.1 +/- 0.3 km.h-1) or V-Tvent (14.9 +/- 0.2 km.h-1) was not significantly different from the V-Tlac (15.1 +/- 0.3 km.h-1) or V-Tvent (14.9 +/- 0.3 km.h-1) but was significantly lower than the V-MLSS (P < 0.05). The [Lac-]BMIN provided the lowest correlation with V-MLSS (r = 0.61) and the worst estimate of V-MLSS (SEE = 0.75 km.h-1) compared with the other measures of lactate accumulation. The V-Tlac was not significantly different from V-MLSS and provided the highest correlation (r = 0.94) and a close estimate (SEE = 0.33 km.h-1) of the V-MLSS. CONCLUSIONS: It is concluded that of the measures studied relating to blood lactate accumulation during submaximal exercise, V-Tlac provides the best estimate of the V-MLSS and the V-Tlac had equal predictive power for 8-km race performance.

Adult↗
PubMed2001

Lactate dehydrogenase activity and insulin and lactate levels at an altitude below sea level (-350 m) compared to those at an altitude above sea level (620 m) after exercise.

This study was designed to investigate the effect of exercise at 350 m below sea level altitude (-350 m) on the serum levels of lactate dehydrogenase (LDH), insulin, and lactate. The study was carried out on ten trained adult males with mean age of 23.3 +/- 3.4 years following a 21-km noncompetitive run. Venous blood was withdrawn from the subjects before exercise and 5 min post exercise. For comparison purposes, a similar study was performed with the same subjects but at 620 m above sea level (+620 m). The results show a significant increase in LDH and lactate levels after exercise only at low altitude (-350 m). Serum insulin levels decreased significantly after exercise at both altitudes. These changes in serum levels of LDH, insulin, and lactate at different altitudes suggest that a type of metabolic adjustment is present that meets energy requirements during exercise.

Adult↗
PubMed2002

L-Lactate transport into rat heart mitochondria and reconstruction of the L-lactate/pyruvate shuttle.

In vitro reconstruction of the L-lactate/pyruvate shuttle has been performed, which allows NADH oxidation outside rat heart mitochondria. Such a shuttle occurs due to the combined action of the novel mitochondrial L-lactate/pyruvate antiporter, which differs from the monocarboxylate carrier, and the mitochondrial L-lactate dehydrogenase. The rate of L-lactate/pyruvate antiport proved to regulate the shuttle in vitro.

Animals↗
PubMed2003

Functional replacement of the Escherichia coli D-(-)-lactate dehydrogenase gene (ldhA) with the L-(+)-lactate dehydrogenase gene (ldhL) from Pediococcus acidilactici.

The microbial production of L-(+)-lactic acid is rapidly expanding to allow increased production of polylactic acid (PLA), a renewable, biodegradable plastic. The physical properties of PLA can be tailored for specific applications by controlling the ratio of L-(+) and D-(-) isomers. For most uses of PLA, the L-(+) isomer is more abundant. As an approach to reduce costs associated with biocatalysis (complex nutrients, antibiotics, aeration, product purification, and waste disposal), a recombinant derivative of Escherichia coli W3110 was developed that contains five chromosomal deletions (focA-pflB frdBC adhE ackA ldhA). This strain was constructed from a D-(-)-lactic acid-producing strain, SZ63 (focA-pflB frdBC adhE ackA), by replacing part of the chromosomal ldhA coding region with Pediococcus acidilactici ldhL encoding an L-lactate dehydrogenase. Although the initial strain (SZ79) grew and fermented poorly, a mutant (SZ85) was readily isolated by selecting for improved growth. SZ85 exhibited a 30-fold increase in L-lactate dehydrogenase activity in comparison to SZ79, functionally replacing the native D-lactate dehydrogenase activity. Sequencing revealed mutations in the upstream, coding, and terminator regions of ldhL in SZ85, which are presumed to be responsible for increased L-lactate dehydrogenase activity. SZ85 produced L-lactic acid in M9 mineral salts medium containing glucose or xylose with a yield of 93 to 95%, a purity of 98% (based on total fermentation products), and an optical purity greater than 99%. Unlike other recombinant biocatalysts for L-lactic acid, SZ85 remained prototrophic and is devoid of plasmids and antibiotic resistance genes.

Culture Media↗
PubMed1979

The movement of pyruvate, lactate and lactate dehydrogenase into rabbit oviductal fluid.

Pyruvate, lactate and lactate dehydrogenase appeared linearly in 2 ml 0.9% NaCl recirculated through the rabbit oviduct for 4 h in vivo. In oviducts from rabbits injected 3 days previously with 100 i.u. hCG, the rate of appearance of all three constituents was considerably reduced. It is considered unlikely that the lactate dehydrogenase secreted brings about the interconversion of pyruvate and lactate in the oviduct lumen.

Animals↗
PubMed2003

Determination of lactate or oxalate using injected lactate oxidase and peroxidase by capillary electrophoresis with UV detection.

Two reactions, catalyzed by lactate oxidase (LO) and peroxidase, are initiated by a single injection of the enzymes and the substrate 2,2'-azino-bis(3-ethylene-thiazoline-6-sulfonic acid) (ABTS) into the capillary previously filled with the sample (lactate or lactate-oxalate mixture) and the run buffer containing NADH. The oxidized ABTS product upon reaction with NADH is converted to NAD(+) which is separated and detected in less than 2 min at 266 nm with a sample throughput of 7 min (including wash steps between samples). Simplex trade mark software is used to optimize the enzyme concentrations and reaction temperature. Consumption of the more expensive LO enzyme is only 1.4 x 10(-3) U per assay assuming 27 nL per injection. Linearity is established within the range from 0.0025 to 1 mM with R(2) of 0.9982. Recoveries of lactate from five spiked serum samples averaged 101%. Application of this method for the determination of oxalate as an inhibitor of LO is demonstrated.

Electrophoresis, Capillary↗
PubMed1996

The pharmacokinetics of ceftazidime in lactating and non-lactating cows.

The pharmacokinetics of ceftazidime (CAZ) were studied in lactating (LTG) and non-lactating (NLTG) cows. Two groups (LTG and NLTG) of 5 healthy dairy cows were given ceftazidime (10 mg/ kg body weight) intravenously (i.v.) and intramuscularly (i.m.). Serum and milk (LTG) and serum samples (NLTG) were collected over a 24-h period post-administration. CAZ concentrations in serum and milk were determined by high-performance liquid chromatography, and an interactive and weighted-non-linear least-squares regression analysis was used to perform the pharmacokinetic analysis. The pharmacokinetic profiles in LTG and NLTG cows which had received CAZ i.v. fitted a three-compartment model and a two-compartment model, respectively. The CAZ concentration-time curves in serum and the area under the curve were greater and more sustained (p < 0.05) in the LTG cows by both routes, while the serum clearance (Cls = 72.5 +/- 18.1 ml/h per kg) was lower (p < 0.05) than that in the NLTG cows (Cls = 185.9 +/- 44.2 ml/h per kg). CAZ given i.v. exhibited a relatively long half-life of elimination (t1/2 beta (LTG) = 1.1 +/- 0.2 h; t1/2 beta (NLTG) = 1.4 +/- 0.3 h). Compared with other cephalosporins, CAZ had good penetration into the mammary gland (47.7 +/- 38.2% for CAZ i.v.; 51.1 +/- 39.0% for CAZ i.m.). Finally, the bioavailability of CAZ (F(LTG) = 98.9 +/- 36.8%; F(NLTG) = 77.1 +/- 25.3%) was suitable for its used by the i.m. route in lactating and non-lactating cows.

Animals↗
PubMed1988

Lactate threshold and onset of blood lactate accumulation during incremental exercise after dietary modifications.

This study was designed to clarify the effects of dietary modifications on the lactate threshold (LT) and on the onset of blood lactate accumulation (OBLA) during progressive incremental exercise. Six healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions: a 48-h period of mixed dieting (53% carbohydrates, 30% lipids, 17% proteins) preceding the first exercise test, immediately followed by a 48-h period of either a carbohydrate-rich (68% CHO, 23% lipids, 9% proteins) or a fat-rich (19% CHO, 57% lipids, 26% proteins) iso-caloric diet leading to the second exercise and separated from the third test by a 12-days period. Exercise tests were conducted on an electrically-braked ergocycle, and consisted of a progressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open circuit sampling system. Exercise blood lactate (LA), free fatty acids (FFA), glucose levels and acid-base balance were determined from venous blood samples obtained through an indwelling brachial catheter. Peak lactate values, workload and performance time were not significantly altered by imposed diets. Furthermore, dietary modifications had no significant effect on LT, OBLA fixed at 4 mmol and ventilatory threshold. Increased pH and FFA mobilization were observed with fat-rich diet, while CHO-rich diet markedly increased the respiratory exchange ratio (R). It is concluded that LT and OBLA are not significantly altered by fat or CHO enrichment of diets.

Adult↗