Extending lactational amenorrhoea in Manila: a successful breast-feeding education programme.

An experimental breast-feeding education programme conducted at the Philippine General Hospital in Manila demonstrated that women could be motivated to improve their breast-feeding practices and lengthen their period of lactational amenorrhoea in comparison to a control group. Mothers who participated in the programme breast-fed their babies more frequently, delayed the introduction of regular supplements, used fewer bottles and pacifiers and maintained night feeding longer than mothers who were not exposed to the positive breast-feeding messages. The programme was successful in lengthening the period of amenorrhoea among women with elementary, high school, or technical school education, but not among college-educated women. Different educational approaches may be necessary for women of different education levels.     

Determinants of breast-feeding and post-partum amenorrhoea in Orissa

A life table analysis is made of the duration of breast-feeding and post-partum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amenorrhoea are strongly related.     

Continuously recorded suckling behaviour and its effect on lactational amenorrhoea.

The hypothesis that the month-specific rate of return to ovarian cyclicity after childbirth is causally related to suckling pattern was tested for a population of New Mexican women recruited within the service area of New Mexico Highlands University and for a nationwide USA subpopulation of women recruited through membership of the Couple to Couple League (CCL). Survival analysis for time-dependent covariates was used, and significant predictors of the first postpartum menses were found. Important differences were detected in the suckling pattern for the two groups and a 5:2 differential was found in their respective rates of menstrual cycle recovery. Although the two groups were comparable perinatally, daily and time-windowed breast-feeding performance fell off at twice the rate for the New Mexico population when contrasted with the CCL sample. For both populations, the introduction of solid feeds was a strong and significant predictor of returning menstrual cyclicity, independent of suckling pattern.     

The duration of lactational amenorrhoea in urban Bangladeshi women

The duration of lactational amenorrhoea, and infant feeding patterns and behaviour, were investigated in a sample of 97 mother-infant pairs living in a poor urban area of Dhaka, Bangladesh. A seven-hour time allocation method was used to determine the number of breast-feeding bouts and their duration. The seven-hour observation period was conducted on five occasions: at birth, 1 month, 4 months, 8 months and either 10 or 11 months. The median duration of lactational amenorrhoea was determined to be 24.07 weeks using survival analysis. Mothers who breast-fed their babies for longer and more frequently had, on average, a longer period of lactational amenorrhoea. There was no relationship between sociodemographic characteristics of the mother and duration of lactational amenorrhoea, nor was there any significant relationship between maternal anthropometry and birth weight of the baby and duration of lactational amenorrhoea, but there was a tendency for women with lower body mass index to have longer durations. Using the Cox proportional hazards model, the best predictor of duration of lactational amenorrhoea was the mean of months 0 and 1 durations of breast-feeding, adjusted for the mean frequencies for those months. The introduction of weaning food was also an important predictor.     

Autorhythmometry in hypertension: some methodological aspects and clinical implications

Autorhythmometry of blood pressure is a technique easy to be performed and well accepted by hypertensive patients. A simple inspection of data self-collected 5 times a day for many days constitute a sufficiently reliable automonitoring of blood pressure both in basal conditions and in relation to the efficacy of some dietary and/or pharmacological treatment. Several examples are reported to show that more sophisticated statistical manipulation of the data collected may give rise to a better understanding of some clinical and physiological aspects. Both analysis of variance, performed on individual subsets of data averaged at each sampling hour, and single cosinor, performed on longitudinal time series, may be used to detect and quantify a circadian rhythm as a systematic daily variation, averaging towards zero the noise superimposed to the actual time series. Serial section analysis of the data, along all the experimental span, is useful to detect a) the reproducibility of the rhythm b) the variation of its parameters induced by changes in the experimental conditions c) the long-term trend. In the first subject the influence on the circadian rhythm of the pulse rate, temperature and blood pressure, due to a 4 h advancing shift in the rest-activity synchronizer, is well documented. In the first hypertensive patient a circadian rhythm is demonstrated also in blood pressure during two non-consecutive months. No difference is detected in both mesor and amplitude of blood pressure and a full resynchronization of the acrophase is achieved when a 1 h delaying shift in the rest activity synchronizer is imposed. In the second patient a well reproducible rhythm of systolic blood pressure and a low noise/signal ratio is documented by the serial section display. In the third patient the 'lability' of hypertention seems mainly due to salt sensitivity, as documented by the significant lowering of the mesor in the second experimental span, when a lowering of only 30 mEq/day in salt intake is imposed. The serial section better documents the salt-sensitivity of this patient, during a span when loading and depressing of salt intake is imposed. In the last patient the prompt effect of therapy in lowering blood pressure within normal range is well documented by serial section with 3 day interval. A possible effect of masking the circadian rhythm of blood pressure, due to therapy, is inferred by the serial section display with an interval of the same length (33 days) as the subspan without therapy. The possibility of prevention in the hypertensive disease is discussed, with the aim of autorhythmometry and statistical methods employed in this paper.     

Effectiveness of lactational amenorrhoea in prevention of pregnancy in Manila,the Philippines: non-comparative prospective trail.

OBJECTIVE: To determine the contraceptive efficacy of the lactational amenorrhoea method. DESIGN: Non-comparative prospective trial. SETTING: Urban Manila, the Philippines. SUBJECTS: 485 lower income, educated women with extensive experience of breast feeding. INTERVENTION: Women were offered all available contraceptives for use after birth. Those who chose the lactational amenorrhoea method were taught the method, screened for the study, and followed for 12 months to determine the risk of pregnancy when the method was used. MAIN OUTCOME MEASURES: Life table pregnancy rates during correct and incorrect use of the method, censored monthly in the event of sexual abstinence or the use of another contraceptive method. RESULTS: The lactational amenorrhoea method was 99% effective when used correctly (that is, during lactational amenorrhoea and full or nearly full breast feeding for up to six months). At 12 months the effectiveness during amenorrhoea dropped to 97%. CONCLUSIONS: The lactational amenorrhoea method provided as much protection from pregnancy as non-breast feeding women experience with non-medicated intrauterine devices and barrier methods. The contraceptive effect of lactation cannot be attributed to lactational or postpartum abstinence.     

Variability of breast sucking, associated milk transfer and the duration of lactational amenorrhoea.

Quantitative relationships between physical parameters of sucking, milk transfer and the duration of amenorrhoea were examined in normal mother-baby pairs under exclusive breastfeeding. Sucking pressures were recorded twice on the second and once on the fifth month after birth, during complete breastfeeding episodes, by means of a catheter attached to the nipple and connected to a pressure transducer, the signals of which were analysed by computer. Babies were weighed before and after each sucking episode to estimate milk transfer. In the first nursing episode after noon, 2-month-old babies sucked from 140 to > 800 times during 4-15 min from the first breast, obtaining from 20 to > 100 g milk. The physical parameters of sucking and milk transfer exhibited high inter-individual but low intra-individual variabilities. There were significant differences in the physical parameters of sucking and milk transfer efficiency between first and second breast and between the second and fifth months after birth. Milk transfer efficiency was inversely correlated with time occupied by non-sucking pauses > or = 1.5 s, and was directly correlated with mean intersuck intervals in the first breast and with duration of the sucking episode, number of sucks, mean pressure and area under the pressure curve in the second breast. There was no correlation between the physical parameters of sucking and duration of lactational amenorrhoea (n = 62). However, significantly more mothers had amenorrhoea lasting > 180 days among those whose babies spent a longer proportion of the nursing episode in non-sucking pauses > or = 1.5 s. This finding indicates that sensory stimulation of the nipple produced during a nursing episode by stimuli other than sucking itself may have an important role in sustaining lactational amenorrhoea. It is concluded that nursing episodes have a complex structure that allows the development of a breastfeeding phenotype in each mother-baby pair, exhibiting important inter-individual variability. The present analysis does not support the contention that this source of variability accounts for the variability in the duration of lactational amenorrhoea.     

Energy transfer method in membrane studies: some theoretical and practical aspects

Some applications of resonance energy transfer (RET) method to distance estimation in membrane systems are considered. The model of energy transfer between donors and acceptors randomly distributed over parallel planes localized at the outer and inner membrane leaflets is presented. It is demonstrated that RET method can provide evidence for specific orientation of the fluorophore relative to the lipid-water interface. An approach to estimating the depth of the protein penetration in lipid bilayer is suggested.     

Central regulation of thyrotropin secretion in rats: methodological aspects, problems and some progress

The concept of the regulatory role of the hypothalamic and brain neurotransmitters in the secretion of the hypothalamic releasing hormones and corresponding anterior pituitary hormones has been generally accepted. The tuberoinfundibular portal vessels form an anatomical framework for regulating these hormones. Our present knowledge about the origin and course of the main aminergic and peptidergic bundles and their collaterals into the hypothalamus conforms with the accepted concept. The general methods in neuroendocrinology are well established. In our study, the unique TSH burst induced by a short cold-exposure has proved very useful, since it is mediated through the activation of TRH in the hypothalamus. When used together with the TSH-response caused by the exogenous TRH and with stereotaxic microinfusions of various chemicals into specific areas in the brain, the level of action of the pharmacological agents can be determined. Methodological pitfalls are, however, possible unless care is taken to avoid unspecific stress factors, general anaesthesia and intracerebral injections at unphysiological concentrations. The role of different neurotransmitters in the central TRH-TSH regulation has been clarified in recent years and the simple concepts of the early days elaborated accordingly. The cold-stimulated TSH secretion can be modified by several neurotransmitters. Noradrenaline is a stimulatory transmitter at high hypothalamic centers, but it may also retard TRH release into the portal vessels. It also seems possible that alpha 1- and alpha 2-receptors mediate opposite effects. Nigrostriatal (but not tuberoinfundibular) dopamine has only an inhibitory action on TRH release and/or synthesis. The importance of 5-HT is still controversial, partly because of the unspecificity of the experimental tools available. Evidently both stimulating and inhibiting components are involved. The role of different 5-HT receptors remains to be established. The function of GABA is complicated, too, the real GABAergic action being an inhibition of TRH release from the medial basal hypothalamus. Only histamine and some amino acids affect TRH-induced TSH secretion. Hence the anterior pituitary in the rat is not so important a locus as the hypothalamus in the action of neurotransmitters on the TRH-TSH regulation.     

Operation of a multichannel microcalorimetry system in the micro-submicrowatt region: some methodological aspects

Monitoring heat flux values below approx. 4 microW requires in microcalorimetry non-standard experimental procedures in order to achieve high accuracy and reproducibility. With 5 ml ampoules, stable baselines are reached in 70 min if a three-level pre-thermostating procedure is used and if the gas phase above the liquid is reduced to 0.5 ml or less. A pairwise procedure of reference/measuring ampoules is used. Autoclaved sealing material of teflon, sterilized stainless steel ampoules in contact with a standard cell medium and culture plates of polystyrene do not contribute to measured heat flux. Further, we found that a standard cell culture medium develops a significant thermal heat flux, 0.10 microW.ml-1, probably reflecting an oxidation process in the medium itself.     

Analysis of zooplankton feeding experiments: some methodological considerations

Studies of the feeding ecology of zooplankton are noted morefor the problems associated with their quantitative analysesthan for their conclusions. In order to illustrate one particularlyinsidious problem, I use several more or less traditional methodsto obtain rather different results from experiments with themarine calanoid copepod Eucalanus pileatus and a variety ofphytoplankton. If the probabilities of encountering algal cellsof various taxa are proportional to their environmental frequencies,as is implicit in a feeding mechanism based upon improbableanalogy with a leaky sieve, E. pileatus seems to capture largecells more efficiently than small ones. If these frequenciesare weighted by the average cross-sectional areas of individualcells (i.e., those of spheres of equivalent volume), as wouldbe appropriate if they were intercepted (i.e., encountered)by single fibers (e.g., maxillary setae or setules), then E.pileatus seems to capture small cells more efficiently thanlarge ones. Inasmuch as these conflicting observations resultfrom different conceptions of the feeding mechanism, and sievingis only one of several reasonable alternatives that emerge fromthe relevant fluid dynamics, evidently the mechanism of feedingmust be elucidated before passive selection can be properlycharacterized. However, the feeding mechanism need not be understoodin order to study consumers whose behavior changes with therelative abundance of prey. I find that selectivity by E. pileatusvaries with algal concentration, and that large cells are consumeddisproportionately relative to their frequencies at high concentrations(in accord with results of other investigators), but that smallcells are consumed disproportionately relative to their encounterprobabilities (here a function of size as well as frequency,although other characteristics, such as scent and shape, maybe involved as well) irrespective of concentration. This observationis incompatible with the contemporary paradigm of zooplanktonfeeding, but it does not seem unreasonable considering the sizeand spatial distributions of particles in the ocean. Consequently,these results support the alternative hypothesis that consumersadapt to characteristics of the prey that they encounter mostfrequently.     

Immunogold detection of co-localized neuropeptides: methodological aspects.

Whatever the protocol used, electron microscopic immunogold detection still suffers from a lack of sensitivity. In rat supraoptico-posthypophyseal neurons, unlabeled secretory granules are always detectable after electron microscopic immunocytochemistry, and their real status remains questionable. To improve the sensitivity of this approach, we assessed a protocol to visualize either one or the other of co-localized neuropeptides, i.e., vasopressin or galanin, after two successive rounds of immunogold with the same primary antibody performed on both faces of the grid. The use of different-sized gold particles enabled us to visualize the respective contribution of each face of the section to the final labeling. Our results showed a moderate but significant increase in both the proportion of labeled granules and the labeling intensity. Although limited, this improvement of immunogold detection strengthens the relevance of quantitative studies at the electron microscopic level, likely to reveal fine variations of the neuron peptidergic content. However, this enhancement depended on the peptide studied. The present data confirmed a progressive decrease of vasopressin immunoreactivity, already suggested by the single-staining procedure, all along the hypothalamo-posthypophyseal tract. In contrast, labeling intensity for galanin remained steady. Finally, our double-face labeling supported a preferential routing of galanin-containing secretory granules towards dendrites.     

Postpartum lactational amenorrhoea as a means of family planning in the Sudan: a study of 500 cases

The lactational histories of 500 Sudanese women were studied retrospectively to examine postpartum lactational amenorrhea as a method of family planning. Particular attention was given to the factors affecting postpartum lactational amenorrhea, including supplementary feeding and the use of modern contraceptive methods. Breast-feeding was overwhelmingly practised (90%) among this sample, which was roughly representative of the Sudanese population as a whole. The prevalence of amenorrhea among this group of lactating women was quite high (73%). Duration of lactational amenorrhea ranged from 2 to 36 months with a median of 12 months. Introduction of supplementary feeding had little effect on lactational amenorrhea up to the 9th month of breastfeeding. Beyond the 12th month of breastfeeding, lactational amenorrhea was significantly prolonged by postponing the introduction of supplementary feeding until the 4th month or later. Ovulation, and hence conception, during lactational amenorrhea was unpredictable. It occurred as early as the 3rd or as late as the 36th month postpartum. Conceptions interrupting lactational amenorrhea soon after delivery (3-9 months) were more frequent among primiparous women. The failure rate of lactational amenorrhea as a contraceptive was 8.4%. Though extremely high compared to that of the pill, lactational amenorrhea was more useful as a fertility control mechanism because, in this study, a high proportion of women initiated pill use, but soon discontinued it because of side effects. Modern contraceptive practice was not prevalent. Amenorrheic mothers accepted the pill after the 6th month postpartum (41%, compared to lactating mothers whose menses had returned who started much earlier. 49% of the women studied relied completely on the protection of lactational amenorrhea. 57% of all lactating women who used the combined pill reported a reduction in milk production. Knowledge of modern contraception was poor and incorrect in many cases, leading to several policy implications, including usage of sterilization.     

Vigilance monitoring--review and practical aspects.

Vigilance monitoring is increasingly important in the industrialised world because working tasks are becoming increasingly monotonous and less physically exhausting, resulting in a high risk of falling asleep unintentionally. Among existing tests for the assessment of vigilance, objectiveness plays the most important role in preventing volitional influence by the test subject. In addition, the tests should be simple so that a monotonous situation will emerge. This review gives an overview of important vigilance monitoring systems that are currently in use for research purposes and industrial application. The tests presented are the Mackworth clock test, the VIGIMAR, the Karolinska drowsiness test, tests based on blood pressure and heart rate changes, the psychomotor vigilance test, and experimental tests relying on pupillography and electrodermal activity.     

Nursing behaviour and its relation to duration of post-partum amenorrhoea in an Andean community

Nu?oa is a high altitude rural Peruvian community characterized by socioeconomic stratification and differential access to the market economy. Nursing practices and the effects of nursing are also stratified; this translates into a risk of menses at 12 months post-partum nearly seven times greater in wealthier than in poorer women. Most nursing occurs in the morning, among those who practice on-demand breast-feeding. Nursing episodes are clustered into sessions; the amount of breast-feeding is regulated by varying the number of episodes per session rather than by changing the duration of suckling episodes or the frequency of sessions per hour. Thus, resumption of ovulation is not dependent on the variable spacing of nursing episodes or sessions. The components of nursing activity most likely to be responsible for variation in the duration of post-partum amenorrhoea in these nursing women are mean session duration and mean number of episodes per session. The mean duration of morning nursing sessions is negatively associated with infant's age, reflecting the greater reliance of younger children on breast-milk. The mean duration of afternoon nursing sessions is positively associated with mother's age, independent of infant's age, possibly reflecting maternal age-related variation in milk production capabilities. Baby minding by older daughters may also help to explain variation in afternoon nursing.     

Lipidomics: practical aspects and applications

Lipidomics is the characterization of the molecular species of lipids in biological samples. The polar lipids that comprise the bilayer matrix of the constituent cell membranes of living tissues are highly complex and number many hundreds of distinct lipid species. These differ in the nature of the polar group representing the different classes of lipid. Each class consists of a range of molecular species depending on the length, position of attachment and number of unsaturated double bonds in the associated fatty acids. The origin of this complexity is described and the biochemical processes responsible for homeostasis of the lipid composition of each morphologically-distinct membrane is considered. The practical steps that have been developed for the isolation of membranes and the lipids there from, their storage, separation, detection and identification by liquid chromatography coupled to mass spectrometry are described. Application of lipidomic analyses and examples where clinical screening for lipidoses in collaboration with mass spectrometry facilities are considered from the user point of view.     

Mitochondria and cell death. Mechanistic aspects and methodological issues.

Mitochondria are involved in cell death for reasons that go beyond ATP supply. A recent advance has been the discovery that mitochondria contain and release proteins that are involved in the apoptotic cascade, like cytochrome c and apoptosis inducing factor. The involvement of mitochondria in cell death, and its being cause or consequence, remain issues that are extremely complex to address in situ. The response of mitochondria may critically depend on the type of stimulus, on its intensity, and on the specific mitochondrial function that has been primarily perturbed. On the other hand, the outcome also depends on the integration of mitochondrial responses that cannot be dissected easily. Here, we try to identify the mechanistic aspects of mitochondrial involvement in cell death as can be derived from our current understanding of mitochondrial physiology, with special emphasis on the permeability transition and its consequences (like onset of swelling, cytochrome c release and respiratory inhibition); and to critically evaluate methods that are widely used to monitor mitochondrial function in situ.     

Gene-environment interactions in addictive disorders: epidemiological and methodological aspects

The gene-environment interactions' approach could explain some epidemiological and clinical factors associated with addictive behaviours. Twin studies first help to disentangle the respective roles of environment and genetic effects, finding convincing evidence for common genetic vulnerability in several addictive behaviours, and helping to delimit what syndrome could belong to the addictive disorder spectrum. Assessing gene x environment interaction (G x E) needs specifically designed studies, using multiplicative or additive approaches. Focusing on this G x E interaction already showed its relevancy in many recent studies, using both epidemiological and molecular approaches. For example, in a non-human primate model of alcohol dependence assessing the respective role of genetic vulnerability (having the short allele located in the promoter region of the gene coding for the serotonin transporter) and severe fostering conditions (as locked up in a cage with other inmates for the first six months of life), the only group of monkeys that has a significant risk of using spontaneously alcohol is the one that gathers both risk factors, i.e. being peer-raised and having the short allele. Such approach could help to more accurately select specific candidate genes, to identify more homogenous subgroups of patients (as sharing the same genetic vulnerability), to understand how genetic factors mediate the risk of associated psychiatric disorders, and ultimately, may lead to more focused, i.e. more efficient, prevention strategies.