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PubMed1995

Mechanisms of reoxygenation-induced calcium overload in cardiac myocytes: dependence on pHi.

This study investigated the selective effects of intracellular (pHi) or extracellular change in pH on reoxygenation-induced Ca2+ overload in simulated myocardial hypoxia. Experiments were performed in cultured cardiomyocytes isolated from the ventricle of neonatal ICR mouse. A model of chemical hypoxia with 2 mM sodium cyanide was developed to mimic the ATP depletion of hypoxia. This chemical hypoxia was "reoxygenated" and the dynamics in intracellular Ca2+ concentration ([Ca2+]i) and pHi were monitored using the fluorescent dyes fura-2 and 2', 7'-bis (2-carboxyethyl)-5(6)-carboxyfluorescein, respectively. During a 40-min chemical hypoxia, pHi progressively fell from 7.2 to 6.6. Reoxygenation with control solution caused rapid recovery of pHi and a marked increase in [Ca2+]i (1884 +/- 136 nM). Intracellular acidotic reoxygenation produced by lactate apparently prolonged the time course of pHi recovery and significantly suppressed reoxygenation-induced Ca2+ overload (1170 +/- 118 nM, P = 0.008). Extracellular acidotic reoxygenation with 2-(N-morpholino) ethanesulfonic acid (pK = 5.96) buffer somewhat suppressed the Ca2+ overload; however, the maximal value of [Ca2+]i was not reduced significantly compared with the control (1790 +/- 122 nM, P = 0.130). In addition, inhibition of Na(+)-H+ exchange by amiloride potentiated prolongation of intracellular acidosis during reoxygenation and resulted in a minimal increase in [Ca2+]i (985 +/- 102 nM, P = 0.004). These results suggest that reoxygenation-induced Ca2+ overload is closely correlated with intracellular pH in the initial phase of reoxygenation, and the protective effects of extracellular acidosis is principally mediated by intracellular acidification of reoxygenated cardiomyocytes.

Acids↗
PubMed1999

Prolonged breastfeeding in Bangladesh: indicators of inadequate feeding practices or mothers' response to children's poor health?

The association between breastfeeding and diarrhoeal morbidity was examined in a prevalence study of 5502 children aged 6-71 months from rural and urban Bangladesh. Breastfeeding was found to be associated with reduced prevalence of diarrhoea. This association was most pronounced at the age of six months and declined linearly to zero at approximately 30 months of age; thereafter, breastfeeding was increasingly associated with diarrhoeal illness. The linear association was found only among those children who have no access to modern health services and information, when controlling for urban and rural differences. The literature provides two opposing explanations for the positive association of prolonged breastfeeding with diarrhoeal illness. The first explanation suggests that breastfeeding can be seen as mothers' response to children's poor health. The second explanation incriminates sub-optimal child feeding practices, characterised by prolonged breastfeeding and inadequate quality and quantity of complementary foods, as the cause of malnutrition and diarrhoea. Further studies are needed to identify which explanation is correct, given the public health implications in terms of children's survival, growth and development.

Bangladesh↗
PubMed1991

[Sheehan's syndrome in sudano-sahelian Africa. 40 observations].

Postpartum hypopituitarism or Sheehan's syndrome is frequent in Sahelian Africa. From February 1983 to July 1988, the authors observed 40 cases at National hospital of Niamey (Republic of Niger). These patients were Black African women living in rural areas, without medical assistance during the last delivery. Two signs were required for the diagnosis: absence of postpartum lactation and prolonged amenorrhoea. A 15 points score was used for identification of each case. Postpartum hypopituitarism is a severe disease in Sahelian Africa: after the pituitary necrosis, 80% children died. 60% of patients had no living child or only one malnourished infant with a poor prognosis. The social future of these sterile African women seemed uncertain. Hormonal treatment (estrogens, thyroxin, cortisone) is justified but expensive. Exceptionally a pregnancy developed after Sheehan's syndrome under treatment with childbirth of a living infant.

Female↗
PubMed1993

Interstitial purine metabolites and lactate during regional myocardial hypoxia.

OBJECTIVE: Adenosine is a well known vasodilator believed to contribute to metabolic adjustments of the coronary circulation. The purpose of this study was to assess changes in interstitial fluid adenosine, adenosine metabolites, and lactate during prolonged regional, non-ischaemic myocardial hypoxia. METHODS: To induce regional hypoxia, the left anterior descending coronary artery of anaesthetised dogs (n = 9) was perfused at constant pressure (100 mm Hg) with deoxygenated blood (PO2 approximately 2.6 kPa) for 60 min via an extracorporeal shunt. Cardiac interstitial fluid was sampled by cardiac microdialysis, using dialysate metabolite levels as indices of interstitial fluid concentrations. RESULTS: During hypoxia, coronary blood flow increased 3.9-fold, while myocardial oxygen consumption was maintained relatively constant. There were no changes in global cardiac function, systemic arterial pressure, or heart rate during regional hypoxia, indicating that the hypoxic stimulus did not augment sympathetic nervous system activity. Dialysate adenosine was not increased at any point of the hypoxic period, but was decreased by 25 min hypoxia. Dialysate levels of inosine, hypoxanthine, and xanthine were increased transiently during the first 10 min of hypoxia while there was a sustained increase in dialysate lactate. In the presence of erythro-9-(2-hydroxy-3-nonyl) adenine, an adenosine deaminase inhibitor, adenosine was the predominant purine metabolite and increased transiently during hypoxia. CONCLUSIONS: Flux through the adenosine production and degradation pathways is transiently increased during hypoxia. However, the lack of an increase in interstitial fluid adenosine does not support a role for adenosine in the sustained hyperaemic response to regional myocardial hypoxia.

Adenosine↗
PubMed1977

Breastfeeding and abstinence among the Yoruba.

Contemporary patterns of breastfeeding and postpartum abstinence among the Yoruba of Nigera are examined. Quite extensive periods of postpartum abstinence are still observed by most rural and poorer urban women to prolong breastfeeding and increase child survivorship. Differentials in duration of breastfeeding and abstinence relate to both socioeconomic factors and age, suggesting the likelihood of large future reductions. Implications for family planning prospects and policies are noted.

Adolescent↗
PubMed1984

The demographic transition.

Demographic transition is a set of changes in reproductive behavior that are experienced as a society is transformed from a traditional pre-industrial state to a highly developed, modernized structure. The transformation is the substitution of slow growth achieved with low fertility and mortality for slow growth maintained with relatively high fertility and mortality rates. Contrary to early descriptions of the transition, fertility in pre-modern societies was well below the maximum that might be attained. However, it was kept at moderate levels by customs (such as late marriage or prolonged breastfeeding) not related to the number of children already born. Fertility has been reduced during the demographic transition by the adoption of contraception as a deliberate means of avoiding additional births. An extensive study of the transition in Europe shows the absence of a simple link of fertility with education, proportion urban, infant mortality and other aspects of development. It also suggests the importance of such cultural factors as common customs associated with a common language, and the strength of religious traditions. Sufficient modernization nevertheless seems always to bring the transition to low fertility and mortality.

Birth Rate↗
PubMed1988

Synaptic and neuronal-glial plasticity in the adult oxytocinergic system in response to physiological stimuli.

Magnocellular oxytocinergic neurons in the hypothalamus offer a striking example of a mammalian neuronal system whose basic architecture and synaptic circuitry can be reversibly modified in adulthood. During parturition, lactation and prolonged osmotic stimulation, glial coverage of oxytocinergic neurons markedly diminishes and their surfaces are left in extensive juxtaposition; concurrently, there is formation of new synapses, which are predominantly GABAergic and which couple two or more oxytocinergic neurons simultaneously. These structural changes do not permanently modify the anatomy of the system since upon cessation of stimulation, neuronal juxtapositions and shared synapses disappear, to reappear upon new stimulation. At present, we can only speculate about the cellular mechanisms and factors responsible for these reversible neuroanatomical changes. However, oxytocin itself appears to be of primary importance since it can induce similar anatomical changes when chronically infused into the third ventricle.

Animals↗
PubMed1991

Breast feeding and the older infant.

The possible benefits and disadvantages to the older infant of breast-feeding being continued after the introduction of solid foods are reviewed. The limited evidence from industrialised countries suggests that prolonged partial breast-feeding has little influence on child health and growth. In contrast, in poor areas of the developing world, the continuation of breast-feeding for 1-2 years after the introduction of other foods appears to have several major benefits. These include the supply of nutrients, the delivery of protective, digestive and trophic agents, and extending the period of infertility in the mother. Partial breast-feeding after 6 months is associated with reduced severity of infectious diseases particularly in severely malnourished individuals. There is no evidence that partial breast-feeding plays a causal role in poor growth performance. In poor areas of the developing world, breast-feeding, together with the provision of adequate amounts of other foods, should be encouraged for the first two years of life.

Breast Feeding↗
PubMed1985

Acidaemia and hyperkalaemia following low-voltage electric shock in the anaesthetized cat.

Plasma K+ and Na+ concentrations ( [K+], [Na+] ), gas tensions (PO2, PCO2), pH levels and lactate concentrations ( [lactate] ) were measured in blood samples obtained before and after applying low-voltage electric shocks (13-130 V a.c., 5-50 mA, 50 Hz) from forelimb to opposite hind limb in cats anaesthetized with pentobarbitone. The current intensities used did not induce any changes either in rectal temperature or in the electrocardiogram in post-shock periods. Marked reductions in pH, increases in [K+] and elevations in [lactate] relative to control values were measured in arterial blood samples following shocks lasting between 10 and 30 s, with the changes in pH and [lactate] more prolonged (45-90 min) than the [K+] alterations (5-10 min). Post-shock acidaemia and hyperkalaemia were significantly attenuated by neuromuscular blockade and were more pronounced in samples obtained from blood draining the skinned hind limb than in arterial blood. In the immediate post-shock periods both arterial and venous blood samples showed elevations in PCO2 and decreases in PO2 compared with control levels. No differences in [Na+] were noted in arterial and venous blood samples obtained before and after shocks. The sequelae of electric shocks noted in this study mainly arose from changes occurring in tetanically contracted muscles during the passage of current and similar residual effects would be expected to be present in human subjects in circumstances where victims of electrical accidents cannot release contact from a low-voltage source. Some of these sequelae may have relevance in explaining the 'delayed deaths' which occasionally follow human electrical accidents.

Anesthesia↗
PubMed1984

Is prolonged breast-feeding associated with malnutrition?

The association between duration of breast-feeding and nutritional status was studied in a population-based sample of 802 children aged 12 to 35.9 months in Southern Brazil during 1982. The prevalence of malnutrition (low weight for age, length for age, and weight for length) was smallest in those children breast-fed for 3 to 6 months, but after this age nutritional status appeared to be worse in those breast-fed for longer. Children still being breast-fed at the time of the survey presented with a significantly higher prevalence of low weight for length than those who had been totally weaned, and those receiving breast-plus bottle-feeding presented with intermediate levels. This association could not be explained by a number of possible confounding variables using a multiple logistic regression analysis. These results are also consistent with a controlled trial on supplementary feeding in the Sudan.

Adolescent↗
PubMed1990

Determinants of early infant weaning: a multivariate approach.

This research provides a multivariate analysis of factors associated with prolonged breast-feeding and conversely early infant weaning. Infant care practices associated with early infant weaning during the first four months of life were: early introduction to artificial milk, the infant sleeping in its own crib versus with its mother, and in general a more rigid feeding schedule. The weaned infant lived in a family with higher economic means, also maternal employment and the availability of a support person to care for the infant were variables more frequently found among infants weaned early. These infants had greater than average numbers of curative health care visits and gained less weight during the first four months of life than breast-fed infants. This study's findings suggest that as changes in life styles and cultural norms are molded by levels of modernization and urbanization, with greater participation of women in the workforce, the tendency to wean early may become even greater.

Breast Feeding↗
PubMed1998

A longitudinal study of prolonged breastfeeding in relation to child undernutrition.

BACKGROUND: In a number of studies prolonged breastfeeding was associated with a higher risk of undernutrition, although most of these studies are limited by their cross-sectional design which does not allow examination of temporal relationships between full weaning and undernutrition. METHODS: The relationship between prolonged breastfeeding and child growth was examined prospectively among children under 36 months old who participated in a large cohort study. At baseline and at each of three 6-monthly follow-up visits breastfeeding status was assessed and all subjects were weighed and measured. RESULTS: Undernourished children were more likely to be breastfed for a longer period of time compared with normal children. We found a small difference between breastfed and fully weaned children in the gain in height over the following 6-month period; however, breastfed children were likely to gain significantly less weight, particularly among children who were aged 6-12 months. Similar findings were noted when these associations were examined among children who were normally nourished at the time of breastfeeding assessment. The inverse association between breastfeeding status and weight gain was significantly larger among children of poor or illiterate mothers compared with children of relatively more affluent or literate mothers, respectively. CONCLUSIONS: Our findings suggest that the inverse association is not causal, and may be explained by poorer complementary feeding among breastfed compared with weaned children. Children from poorer households and whose parents are illiterate are more likely to have less than adequate complementary feeding. The importance of adequate complementary feeding in the second half of infancy needs to be stressed in nutrition education programmes.

Body Height↗
PubMedDate not supplied

Care of low birth weight babies in slums.

We studied 289 newborn infants from birth till one year of age. Low birth weight babies (less than 2.5 kg) were 52.9%. Boys suffered 9.7 episodes of sickness, and girls 8.6 episodes of sickness. The mean episodes of various sicknesses, and their impact on weight gain, feeding pattern and growth pattern are discussed. Six deaths were observed, of which 4 were among the low birth weight babies. Mortality in babies born less than 2 kg was 44.4% and above 2 kg was less than 1%.

Female↗
PubMed1986

Effects of hormonal and nonhormonal contraceptives on lactation and incidence of pregnancy.

From June 1974 to June 1976, 665 women who had given birth to full-term infants and who were willing to nurse the infant were admitted to this study. At three to six weeks postpartum, subjects chose which of four study groups to join. One-hundred-forty-three mothers chose Group I, exclusive lactation with no contraception; 109 chose Group II, lactation and intrauterine contraception (IUD); 228 chose Group III, lactation and an intramuscular injection of 150 mg medroxyprogesterone acetate (Depo-Provera Sterile Aqueous Suspension, DMPA) given every three months; and 185 chose Group IV, lactation and one tablet of 0.6 mg Clogestone Acetate given daily. Mother and child were examined monthly until the child's spontaneous weaning, the mother's dropout, or the study's close in 1979. Mothers from Group I (exclusive lactation) were dropped from study when they requested and were prescribed a contraceptive. During the first six months of study, the percent of mothers who dropped out of Groups I, II, III, and IV for personal or medical reasons was 28.0, 16.5, 11.4, and 27.1, respectively. Pregnancies began to occur in the sixth month postpartum. Overall, pregnancies occurred in 6% of mothers in exclusive lactation, 3% of mothers protected by an IUD, and 8% of mothers protected by Clogestone. No pregnancies occurred in the 228 women receiving DMPA. Some mothers in the Clogestone or DMPA groups were still breast-feeding their children two or three times a day at the study's close, at which time the child was three or more years of age. No ill effects were observed in growth and development of these children during the study. The DMPA group had the most mothers who were breast-feeding for more than 20 months.

Adolescent↗
PubMed1989

Neurosecretory endings in the rat neurohypophysis are en passant.

A combination of Golgi, Phaseolus vulgaris leucoagglutinin, and transmission electron microscopic (EM) techniques was used to investigate the morphology of neurosecretory axons and their endings in the neurohypophysis of the rat. Light microscopy indicated that the neurosecretory processes are very tortuous, varicose, and branched, often running in close association with blood vessels. EM, as well as reconstruction from serial thin sections, demonstrated that the combination of synaptoid membrane specializations, dense core vesicles, and accumulations of microvesicles, thought to indicate areas of preferential hormone release, can occur anywhere that the axons contact the basal lamina (BL) lining the perivascular space. Usually, but not always, this was accompanied by some degree of axonal dilation. Individual neurosecretory axons frequently entwined around, or ran adjacent to, blood vessels, a short length of axon forming multiple "endings." Thin glial (pituicyte) processes were interposed between these endings. Axonal processes were also seen to end blindly as end-bulbs suspended in the perivascular space where they were often surrounded by pituicyte processes. The morphology observed suggests that reductions in the contact length of individual nerve terminals could be mediated through increased pituicyte coverage along BL. Conversely, a reduction of pituicyte coverage along the BL could lead to more areas of axonal contact with the BL inducing or allowing the formation of more endings, such as has been reported to occur during lactation or prolonged elevation of plasma testosterone levels.

Animals↗
PubMed1989

Breastfeeding and return to ovulation in Bangkok.

Twenty-seven breastfeeding mothers and nine non-breastfeeding postpartum comparison mothers in Bangkok, Thailand were followed longitudinally until ovulation resumed. A simple set of guidelines is described involving three obvious milestones for the breastfeeding mother to safely use the natural contraceptive benefit of breastfeeding. Those milestones are the first menses, the initiation of supplementation and the child's monthly birthday. In the absence of menses and supplementation, 93% of breastfeeding mothers remained anovular for 3 months postpartum and 88-89% for up to 6 months. Further, the work of other investigators suggests that the proportion ovulatory provides an overestimate of those at risk of pregnancy. The guidelines suggest a way to estimate the period of lactational infertility and may be most useful on a programmatic level.

Adult↗
PubMed1990

Risk of ovulation during lactation.

60 breastfeeding mothers in Baltimore and 41 in Manila recorded their infant feeding patterns daily, and gave additional information at weekly interviews. Ovarian activity was monitored by assays for hormone metabolites in daily urine samples. On average, women in Baltimore breastfed less often but for longer at each feed than women in Manila, and the mean times until ovulation were 27 and 38 weeks post partum. 41% of first ovulations had luteal phase defects. Anovular first menses were common (45.1%) during the first 6 months post partum but the rate fell greatly thereafter. The risk of ovulation was reduced by a higher frequency of breastfeeds, longer duration of each feed, and less supplementary feeding. During the first 6 months post partum, amenorrhoeic women had low risks of ovulation (below 10%) with partial breastfeeding, and exclusive breastfeeding reduced the risk to 1-5% with either frequent short feeds or infrequent longer feeds. However, if the woman started menstruating before 6 months post partum, or if she continued breastfeeding beyond 6 months, the risk of ovulation rose, and contraception would be needed.

Amenorrhea↗