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PubMed2002

Intravenous L-lactate application in minipigs partially protects acetylcholinesteratic but not butyrylcholinesteratic activity in plasma from inhibition by paraoxon.

OBJECTIVE: Intoxications with organophosphorous compounds such as paraoxon, an inhibitor of serine hydrolases, mainly butyrylcholinesterase and acetylcholinesterase, are frequent. Oximes are the only enzyme reactivators clinically available. In vitro studies have shown that L(+)-lactate reduces the inhibition of acetylcholinesteratic (AChEA) and butyrylcholinesteratic activity of plasma (BChEA) by paraoxon. DESIGN: The purpose of this in vivo study was to determine whether intravenous L(+)-lactate application under normoxic/normocapnic/normohydrogenemic conditions is able to protect AChEA and BChEA from paraoxon inhibition. SETTING: University research institute. SUBJECTS: Eighteen female minipigs. INTERVENTIONS: Animals were anesthetized, intubated, and mechanically ventilated. Every animal received 1 mg of paraoxon per kilogram of body weight in 50 mL of saline over 50 mins. In addition to receiving paraoxon, six pigs of 18 received 2.5 g (0.125 g kg-1 of body weight) of intravenous L(+)-lactate in 50 mL of saline over 50 mins, and six other pigs received 10 g of L(+)-lactate (0.5 g kg-1 of body weight), whereas the six remaining served as controls. MEASUREMENTS AND MAIN RESULTS: In central venous blood, plasma acetylcholinesteratic and butyrylcholinesteratic activity were measured before paraoxon (baseline, 0 mins), immediately after paraoxon (50 mins after start), and 110, 170, 230, 290, 530, and 1010 mins after the start of infusion. Although 10 g of intravenous L(+)-lactate application had a statistically significant protective effect in vivo on AChEA, 2.5 g did not. No significant protective effect on BChEA was achieved with either 2.5 g or 10 g of L(+)-lactate. CONCLUSIONS: Ten grams of L(+)-lactate can increase AChEA when administered simultaneously with paraoxon. Further study of the in vivo effects of L(+)-lactate after paraoxon intoxication and a formal comparison with standard oxime therapy seem warranted. Also, methods for achieving a prolonged elevated lactate concentration in vivo should be investigated.

Acetylcholinesterase↗
PubMed1994

Comparison of effects of breast-feeding practices on birth-spacing in three societies: nomadic Turkana, Gainj, and Quechua.

Variation in the duration and pattern of breast-feeding contributes significantly to inter-population differences in fertility. In this paper, measures of suckling frequency and intensity are used to compare the effects of breast-feeding practices on the duration of lactational amenorrhoea, and on the length of the birth interval in three prospective studies undertaken during the 1980s, among Quechua Indians of Peru, Turkana nomads of Kenya, and Gainj of Papua New Guinea. In all three societies, lactation is prolonged well into the second year postpartum, and frequent, on-demand breast-feeding is the norm. However, the duration of lactational amenorrhoea and the length of birth intervals vary considerably. Breast-feeding patterns among Gainj and Turkana are similar, but Turkana women resume menses some 3 months earlier than do the Gainj. The average birth interval among the Gainj exceeds that of nomadic Turkana by over 15 months. Suckling activity decreases significantly with increasing age of nurslings among both Gainj and Quechua, but not among Turkana. Earlier resumption of menses among Turkana women may be linked to the unpredictable demands of the pastoral system, which increase day-to-day variation in the number of periods of on-demand breast-feeding, although not in suckling patterns. This effect is independent of the age of infants. The short birth intervals of Turkana women, relative to those of the Gainj, may be related to early supplementation of Turkana nurslings with butterfat and animals' milk, which reduces energetic demands on lactating women at risk of negative energy balance.

Adult↗
PubMed2004

Effects of leptin administration on lactational infertility in food-restricted rats depend on milk delivery.

Leptin administration has been shown to prevent the disruptive effects of acute food deprivation on reproductive function in cycling females and lactating females. We examined the ability of intracerebroventricular leptin administration to ameliorate the effects of food restriction for the first 2 wk postpartum on length of lactational infertility. Leptin administration did not reduce the effects of food restriction on reproductive function at either time period (days 8-15 and 15-22 postpartum) or dose (1 and 10 microg/day) administered. Because of the sharp contrast between these results and the ability of leptin to offset the effects of acute food deprivation in lactating rats, the remaining studies investigated the possible causes of this difference. Both central and peripheral leptin administration eliminated food deprivation-induced prolongation of lactational infertility, suggesting that neither route of administration nor dose was a factor. However, we noticed that, whereas chronically food-restricted females continue to deliver milk to their young, acutely food-deprived females do not. To test the hypothesis that the continued energetic drain of milk production and delivery might prevent the ability of exogenous leptin administration to eliminate the effects of undernutrition, leptin was administered to food-restricted, lactating rats prevented from delivering milk. In this situation intracerebroventricular leptin treatment completely eliminated the effects of food restriction on lactational infertility, suggesting that leptin contributes to the maintenance of reproductive function via two pathways: direct binding in the central nervous system and through increasing the availability of oxidizable metabolic fuels.

Animals↗
PubMed2002

Chronic neuropeptide Y infusion during lactation suppresses pup growth and reduces the length of lactational infertility in rats.

In lactating rats, food restriction potentiates the already high levels of hypothalamic neuropeptide Y (NPY). To investigate the role that high levels of NPY might play in the prolongation of lactational infertility that typically accompanies a food restricted lactation we investigated the effects of chronic central infusions of NPY in ad libitum-fed lactating females. First, we compared the effects of intracerebroventricular (icv) infusion of NPY from Days 12-19 postpartum at a dose of 14.4 microg/day with a similar treatment in nonlactating females. In subsequent experiments we examined the effects of NPY infusions into the lateral ventricle at doses of 6 or 20 mug/day or unilaterally into the medial preoptic area at a dose of 1 microg/day from either Days 12-19 or 7-21 postpartum. Effects on food intake; female body weight; and, where appropriate, litter weight and length of lactational diestrus were compared between NPY and vehicle-treated females. As expected NPY infusion produced a robust increase in body weight and food intake in nonlactating females that was accompanied by a suppression of cyclicity. By contrast NPY treatment in lactating rats resulted in a marked decrease in litter growth and an earlier termination of lactational diestrus.

Animals↗
PubMed1991

Energy metabolism of lactating dairy cows treated with prolonged-release bovine somatotropin or energy deficiency.

Two experiments were carried out with lactating Simmental x Red Holstein Friesian dairy cows. In the first experiment, 8 cows each received six injections at 4-wk intervals of either saline or 640 mg of prolonged-release bST. In the second experiment, 14 of 20 cows received 20 MJ NEL less than their daily requirement for 3 wk. Digestible and metabolizable energy were not affected by the treatments. Mobilization of body energy compensated the bST-induced increase of milk energy and supported milk production of underfed cows by two-thirds of the net energy deficit. The utilization of mobilized body energy and metabolizable energy from the diet for maintenance and milk production was unchanged. The bST and energy deficiency increased N utilization for milk production, because bST increased milk N secretion at the same N intake, and energy deficiency partly compensated the reduced N intake by N mobilization. Milk yield oscillated between the bST injections. Mean milk yield increased by 2.8 kg at constant milk composition. During energy deficit, milk yield dropped by 1.7 kg with decreasing milk protein content.

Animals↗
PubMed1998

The role of specific macronutrient availability in the effect of food restriction on length of lactational diestrus in rats.

In lactating rats, food restriction for the first two weeks postpartum extends the period of lactational diestrus by about 1 week. In these studies we investigated whether this effect results from caloric restriction or the reduced availability of a specific macronutrient. In Experiment 1 lactating rats nursing litters of eight pups were assigned to one of four conditions: 1) ad lib. fed; 2) protein-restricted; 3) carbohydrate-restricted; and 4) fat-restricted. Animals in all the restricted conditions were given access to 50% of ad lib. intake of the appropriate nutrient for Days 1-14 postpartum and ad lib. access to the other two macronutrients. In Experiment 2, ad lib. supplementation from one macronutrient source was provided to lactating rats given restricted access to a composite diet. No differential effect of specific macronutrient deprivation or supplementation on length of lactational diestrus was observed in these studies. Thus, the results of both studies are consistent with the hypothesis that caloric restriction plays a primary role in inducing the prolongation of lactational diestrus in food-restricted rats.

Animals↗
PubMed1992

Chronic food restriction amplifies the effect of lactation on the duration of postpartum anestrus in rats.

We studied the effects of food intake and lactation on the duration of postpartum infecundability in rats. Sprague-Dawley rats were given free access to a purified diet (AIN-76A) or a similar diet (modified to contain twice the concentrations of vitamins and minerals) in amounts equal to 50% of that consumed by controls. At -65 d of age, animals were bred. At parturition, dams were allowed to nurse 4-5 pups, or all pups were removed. Thus, four groups were created: lactating control (n = 11), nonlactating control (n = 11), lactating food restricted (n = 8), and nonlactating food restricted (n = 10). Vaginal cytology was observed twice daily for the detection of proestrus, which occurred at 4.5 +/- 0.5 and 6.7 +/- 0.5 d (mean +/- SD) postpartum in nonlactating control and food restricted groups, respectively (P less than 0.005), and at 16.5 +/- 0.5 and 28.8 +/- 0.5 d postpartum in lactating control and food restricted groups, respectively (P less than 0.0001). The interaction between food intake and lactation was significant (P less than 0.0001). These results indicate that maternal food restriction exacerbates the effects of lactation in prolonging postpartum anestrus.

Anestrus↗
PubMed1993

Effect of DL-sodium lactate infusion on excretion of purine bases and oxypurinol.

To investigate whether or not DL-sodium lactate inhibits the renal excretion of purine bases and oxypurinol, we administered physiological saline containing 0.2 mol DL-sodium lactate to 7 normal subjects intravenously. DL-sodium lactate infusion decreased the urinary excretion and the fractional clearance of uric acid, xanthine and oxypurinol, but the fractional clearance of hypoxanthine was not affected. These results suggested that the implications of DL-sodium lactate-induced hyperuricemia must be considered in patients with gout on its long term and high dose administration, and that the implications of DL-sodium lactate-induced prolongation of half-life of oxypurinol must be considered in hyperuricemic patients treated with allopurinol. However, since the high dose and long term administration of DL-sodium lactate is clinically rare, the effect of DL-sodium lactate infusion on the urinary excretion of uric acid, xanthine and oxypurinol may not be clinically important.

Adult↗
PubMed1992

Effect of DCA administration or endurance training on lactate metabolism in mice during and after exercise.

The purpose of this study was to investigate the effect of the activation of tissue oxidative capacity by dichloroacetate (DCA) administration or endurance training on oxidative removal of lactate, which is the major pathway of lactate metabolism, in mice during prolonged exercise and after supramaximal exercise. DCA administration significantly decreased the blood lactate concentration and activated the oxidative removal of lactate during prolonged exercise. DCA administration did not change lactate metabolism in mice after supramaximal exercise. Endurance training significantly decreased the blood lactate concentration during prolonged exercise and also activated the oxidative removal of lactate. Endurance training significantly increased the recovery of the blood lactate concentration after supramaximal exercise, while it did not activate the oxidative removal of lactate. These results suggest that the activation of the tissue oxidative capacity decreases the blood lactate concentration and also can activate the oxidative removal of lactate during prolonged exercise, while it does not activate the oxidative removal of lactate after supramaximal exercise.

Animals↗
PubMed2001

The re-establishment of the normal blood lactate response to exercise in humans after prolonged acclimatization to altitude.

1. One to five weeks of chronic exposure to hypoxia has been shown to reduce peak blood lactate concentration compared to acute exposure to hypoxia during exercise, the high altitude 'lactate paradox'. However, we hypothesize that a sufficiently long exposure to hypoxia would result in a blood lactate and net lactate release from the active leg to an extent similar to that observed in acute hypoxia, independent of work intensity. 2. Six Danish lowlanders (25-26 years) were studied during graded incremental bicycle exercise under four conditions: at sea level breathing either ambient air (0 m normoxia) or a low-oxygen gas mixture (10 % O(2) in N(2), 0 m acute hypoxia) and after 9 weeks of acclimatization to 5260 m breathing either ambient air (5260 m chronic hypoxia) or a normoxic gas mixture (47 % O(2) in N(2), 5260 m acute normoxia). In addition, one-leg knee-extensor exercise was performed during 5260 m chronic hypoxia and 5260 m acute normoxia. 3. During incremental bicycle exercise, the arterial lactate concentrations were similar at sub-maximal work at 0 m acute hypoxia and 5260 m chronic hypoxia but higher compared to both 0 m normoxia and 5260 m acute normoxia. However, peak lactate concentration was similar under all conditions (10.0 +/- 1.3, 10.7 +/- 2.0, 10.9 +/- 2.3 and 11.0 +/- 1.0 mmol l(-1)) at 0 m normoxia, 0 m acute hypoxia, 5260 m chronic hypoxia and 5260 m acute normoxia, respectively. Despite a similar lactate concentration at sub-maximal and maximal workload, the net lactate release from the leg was lower during 0 m acute hypoxia (peak 8.4 +/- 1.6 mmol min(-1)) than at 5260 m chronic hypoxia (peak 12.8 +/- 2.2 mmol min(-1)). The same was observed for 0 m normoxia (peak 8.9 +/- 2.0 mmol min(-1)) compared to 5260 m acute normoxia (peak 12.6 +/- 3.6 mmol min(-1)). Exercise after acclimatization with a small muscle mass (one-leg knee-extensor) elicited similar lactate concentrations (peak 4.4 +/- 0.2 vs. 3.9 +/- 0.3 mmol l(-1)) and net lactate release (peak 16.4 +/- 1.8 vs. 14.3 mmol l(-1)) from the active leg at 5260 m chronic hypoxia and 5260 m acute normoxia. 4. In conclusion, in lowlanders acclimatized for 9 weeks to an altitude of 5260 m, the arterial lactate concentration was similar at 0 m acute hypoxia and 5260 m chronic hypoxia. The net lactate release from the active leg was higher at 5260 m chronic hypoxia compared to 0 m acute hypoxia, implying an enhanced lactate utilization with prolonged acclimatization to altitude. The present study clearly shows the absence of a lactate paradox in lowlanders sufficiently acclimatized to altitude.

Acclimatization↗
PubMed2001

Neonatal and pediatric extracorporeal membrane oxygenation using nonocclusive blood pumps: the Vienna experience.

Neonatal and pediatric extracorporeal membrane oxygenation (ECMO) is carried out commonly using occlusive blood pumps. Centrifugal pumps provide simple and safe technology for transportation on ECMO. The assistence respiratoire extra corporelle (AREC) system enables single needle venovenous ECMO for infants. We report on our experience with neonatal and pediatric ECMO treatments using nonocclusive blood pumps. One-hundred forty-six ECMO treatments were performed for cardiac, neonatal, and pediatric indications in 54, 19, and 27% of cases. Centrifugal pumps were used in 99, and the AREC system in 42 cases. Hospital mortality was estimated retrospectively and influence of type of pump, type of ECMO belonging to indication group, and lactate at ECMO installation were estimated. Irreversible organ failure leading to ECMO termination was investigated within groups of indications. Survival (recent 50 ECMO treatments) was 80, 70, 43, and 30% after meconium aspiration syndrome, acute respiratory distress syndrome, cardiac surgery, and prolonged resuscitation. Lactate exceeding 100 mg/dl at ECMO installation predicted significantly worse outcome. Cerebral damage was the main reason for ECMO termination in all but persistent circulatory failure in the cardiac group. Myocardial recovery resulted in all except 2 cardiac cases. Nonocclusive blood pumps can be used safely in neonatal and pediatric ECMO. Early installation may improve outcome markedly. In cardiac cases results of surgery should be thoroughly investigated on the table before ECMO installation to prevent hopeless ECMO treatments.

Child↗
PubMed1987

Structural plasticity in the rat supraoptic nucleus during gestation, post-partum lactation and suckling-induced pseudogestation and lactation.

In the supraoptic nucleus (SON) of parturient and lactating rats, large portions of the surface membranes of almost all oxytocinergic neurons are directly juxtaposed with no glial interposition. A significant number of the same neurones are also contacted by the same presynaptic terminal ('double' synapses). Our present observations have revealed that direct appositions between adjacent neurons in the SON increase quite rapidly during the day before parturition. 'Double' synapses also become visible during late gestation, but they appear more progressively. Earlier studies have shown that 1 month after weaning, as in virgin rats, there are again very few appositions and 'double' synapses in the nucleus. We show here that the SON can remain structurally modified, and to the same degree, beyond normal weaning time so long as lactation is prolonged by renewing suckling litters. However, if the mothers are deprived of their pups immediately after birth, neuronal appositions disappear within 2 days and 'double' synapses by 10 days. In non-pregnant primiparous rats, continuous exposure to suckling litters leads to pseudogestation and eventually lactation (in 16-22 days). Examination of the SON in such animals revealed that the oxytocinergic system is already modified by day 12 of dioestrus; during suckling-induced lactation, the anatomical changes are identical to those seen during a normal post-partum lactation. These observations indicate that neither gestation nor suckling alone are indispensable for the anatomical reorganization of the SON apparent at lactation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

The importance of catch-up growth after early malnutrition for the programming of obesity in male rat.

OBJECTIVE: To investigate whether catch-up growth after maternal malnutrition would favor the development of obesity in adulthood. RESEARCH METHODS AND PROCEDURES: Pregnant rats were submitted to protein or calorie restriction during the course of gestation. During lactation, pups were protein-restricted, normally fed, or overfed [reduced litter size, control (C) diet]. At weaning, rats were transferred to chow or to a hypercaloric diet (HCD) known to induce obesity. Body weight, food intake, blood parameters, glucose tolerance, adipocyte cellularity, and adipose factors contributing to cardiovascular disease development were measured. RESULTS: Protein and calorie restriction during gestation led to growth retardation at birth. If malnutrition was prolonged throughout lactation, adult body weight was permanently reduced. However, growth-retarded offspring overfed during the suckling period underwent a rapid catch-up growth and became heavier than the normally fed Cs. Offspring of calorie-restricted rats gained more weight than those of dams fed protein-restricted diet. Feeding an HCD postnatally amplified the effect of calorie restriction, and offspring that underwent catch-up growth became more obese than Cs. The HCD was associated with hyperphagia, hyperglycemia, hyperinsulinemia, glucose intolerance, insulin resistance, and adipocyte hypertrophy. The magnitude of effects varied depending on the type and the timing of early malnutrition. The expression of genes encoding factors implicated in cardiovascular disease was also modulated differently by early malnutrition and adult obesity. DISCUSSION: Catch-up growth immediately after early malnutrition should be a key point for the programming of obesity.

Adipocytes↗
PubMed1977

Morbidity in breast-fed and artificially fed infants.

One-half of the healthy newborn infants at a rural medical center were initially breast fed; the proportion declined to 4% by one year of age. Breast-feeding was associated with significantly less illnes during the first year, especially if continued beyond 41/2 months of age. Breat-fedding was associated with a higher level of parental education and, by inference, higher socioeconomic status. The health advantage of breast-feeding was still evident after controlling for parental educational status. In better educated families the difference in significant illness between infants who were artifically fed and those who were breast fed for prolonged periods of time was two- to threefold.

Breast Feeding↗
PubMed1994

Reproductive function and contraception in the postpartum period.

The postpartum period is a time of major cellular and hormonal change enabling the return of pelvic organs and the hypothalamic-pituitary-ovarian axis to the nonpregnant state. Breast-feeding modifies this change and maintains the endocrine profile and uterine endometrium in a "static" state. In nonlactating women, menstruation returns on average by day 55 to 60 postpartum and ovulation returns on average by day 40 to 50 postpartum. Breast-feeding prolongs the return of menstruation to some 8 to 15 months postpartum and the first ovulation on average was between 30 to 40 weeks postpartum. However, in breast-feeding women, the return of menstruation and ovulation can be quite variable and is influenced by the pattern of breast-feeding, in particular, the intensity and pattern of suckling. There is concern that breast-feeding, although an effective contraceptive on a wide population scale, is unpredictable for the individual. An overall pregnancy rate of 2 to 10 per cent during lactational amenorrhea has been reported. Barrier methods, intrauterine contraceptive devices, and progestogen-only contraceptives are some of the highly effective and most commonly used additional methods of contraception by lactating women. Other methods of contraception during this period include the use of periodic abstinence and combined oral contraceptives. This paper provides an overview of postpartum reproductive function in relation to breast-feeding and the use of contraception in this unique period.

Breast Feeding↗
PubMed2001

Maternal lactation for preterm newborn infants.

In recent decades, neonatologists have made considerable progress in life support techniques, especially in the treatment and prevention of respiratory disorders, which has led to a higher neonatal survival rate. Research into neonatal nutrition has also produced great benefits. It has been found that one of the key points regarding the improved survival rate of infants is the necessity for nutrition that is both adequate and as natural as possible. In this respect, it is necessary to achieve a better understanding of the process, protection, support and maintenance of maternal lactation in neonatal units. Humanization of perinatal attention during delivery, respect for the rights of parents and their children, protection of the mother and child bonding process, early skin contact with the mother and greater attention to individualized care are all key factors in the reinforcement of maternal lactation and are issues that must be addressed within the field of neonatology. Research activities need to concern themselves with: (1) acquiring greater knowledge concerning the common problems and difficulties that arise with mothers and their preterm babies; (2) training healthcare professionals in these aspects, for example in the extraction and storage of milk and in improving techniques of emotional and communicational skills; (3) by means of specific programmes such as the setting up of support groups, so that the effort made to encourage the initiation of breastfeeding is justified by its continuation for as long as possible. Thus, we hope to establish standards of care based on starting, encouraging and prolonging maternal lactation, in sufficient quantity and quality, always remembering that the fundamental goal of our research is the well-being of the child and its family.

Breast↗