Determinants and effects of waiting time to coitus.

Nonuse of contraception at first intercourse among adolescents is well documented in the adolescent sexuality research literature. This study provides a formal test of the hypothesis that an increase in the courtship period (i.e., waiting time to intercourse) increases the likelihood that a couple will discuss contraception and use it at first intercourse. The data analyzed are from personal interviews with 1,314 women aged 20-29 in the 1983 National Survey of Unmarried Women. The results are mixed about the effect of waiting time on contraceptive behavior, providing weak support for the hypothesis, but also elucidating individual and relative characteristics of the couples, such as age and education of the respective partners, that affected contraceptive behavior at first intercourse. Support for the hypothesis may prove more robust in data with different characteristics from the survey used here.     

Infertility and age at first coitus: a possible relationship

Reported age at first coitus was shown to be associated with incidence and degree of infertility. Infertility patients reported later first coital ages than gynecological patients in a sample of 792 women seen in a major fertility service. Among the infertility patients, those who had never conceived presented a later first coital age than those who had previously conceived. Routine gynecological patients reported the youngest first coital age of the groups studied.     

Anaemia, Folate, Zinc and Copper Deficiencies Among Adolescent Schoolgirls in Eastern Sudan

Anaemia is a widespread problem especially in the tropics. Among adolescent girls, it has negative consequences on growth, school performance, morbidity and reproductive performance. A cross-sectional study was conducted to investigate the prevalence of anaemia, iron, folate, zinc and copper deficiencies amongst adolescent schoolgirls in New Halfa, eastern Sudan, and to examine the relationship of these micronutrients with haemoglobin (Hb) levels. Out of 187 adolescent schoolgirls, 181 (96.8%) had anaemia (Hb?<?12 g/dl); 21% had mild anaemia (Hb 11.0–11.9 g/dl); 66.8.1% had moderate anaemia (Hb 8.0–10.9 g/dl), and 12.1% had severe anaemia (Hb?<?8 g/dl), respectively. Iron deficiency (S-ferritin?<?12 μg/l), iron deficiency anaemia (<12 m/dl and S- ferritin?<?12 μg/l) and folate deficiency (S-folate?<?3 ng/ml) were prevalent in 17.6%, 16.5% and 69% of these girls, respectively. Nine percent and 5.9% of these girls had zinc (<75 μg/ml) and copper deficiency (<75 μg/ml), respectively. Twenty-six (14%) girls had ≥2 micronutrient deficiencies. S-ferritin and zinc were significantly lower in patients with severe anaemia. Haemoglobin levels were significantly positively correlated with zinc levels (r?=?0.161, P?=?0.03) and with copper levels (r?=?0.151, P?=?0.03). Thus, interventions are required to prevent and control anaemia in this setting. Further research is needed.     

Mortality in women in relation to their childbearing history.

With data from the Office of Population Censuses and Surveys'' longitudinal study the mortality of currently married women aged under 60 in 1971 was investigated in relation to the number of liveborn children reported at the 1971 census, adjusting for their husbands'' social class. Women who had never had children experienced a higher mortality from many causes of death than the parous women, and this was probably due, at least in part, to selective factors. When the analysis was confined to parous women mortality from diabetes mellitus and cervical cancer increased significantly and oesophageal cancer decreased significantly with increasing number of liveborn children. Mortality from all circulatory diseases and from hypertensive disease, ischaemic heart disease, and subarachnoid haemorrhage tended to rise with parity, though the trends were not statistically significant. Mortality from breast cancer decreased significantly with the number of liveborn children, but only when nullipara were included in the analyses. These data suggest that there may be residual and cumulative effects of childbearing which influence patterns of disease in the long term.     

Sucrose to starch: a transition in molecular plant physiology.

The major flux in potato tuber carbon metabolism is the conversion of sucrose through hexose phosphates to starch. The enzymes that mediate this pathway are well characterized, the genes that encode them have been cloned and transgenic plants have been generated. These transgenic studies have confirmed hypotheses based on more indirect methods, but they have also generated new challenges by highlighting the enormous flexibility and complexity inherent in plant metabolism. The investigation of the sucrose-to-starch transition in potato tubers is an excellent example of how the discipline of molecular plant physiology is evolving at both the scientific and technical levels.     

Fractionated radiotherapy might induce epithelial-mesenchymal transition and radioresistance in a cellular context manner

Despite the fact that radiotherapy is a main therapeutic modality in cancer treatment, recent evidence suggests that fractionated radiotherapy (FR) might confer radioresistance through epithelial-mesenchymal transition (EMT). Nevertheless, the effects of FR on EMT phenotype and the potential link between EMT induction and radioresistance development yet to be clarified. The aim of this study was to assess whether FR could promote EMT, and to elucidate if induction of EMT contributes to the acquisition of radioresistance. To this end, two human cancer cell lines (A549 and HT-29) were irradiated (2 Gy/day) and analyzed using wound healing, transwell migration and invasion assays, real-time polymerase chain reaction (for E-cadherin, N-cadherin, Vimentin, CD44, CD133, Snail, and Twist), clonogenic assay, Annexin V/PI, and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Irradiation of A549 (for 5 or 10 consecutive days) resulted in morphological changes including elongation of cytoplasm and nuclei and pleomorphic nuclei. Also, irradiation-enhanced migratory and invasive potential of A549. These phenotypic changes were in agreement with decreased expression of the epithelial marker (E-cadherin), enhanced expression of mesenchymal markers (N-cadherin, Vimentin, Snail, and Twist) and increased stemness factors (CD44 and CD133). Moreover, induction of EMT phenotype was accompanied with enhanced radioresistance and proliferation of irradiated A549. However, FR (for 5 consecutive days) did not increase HT-29 motility. Furthermore, molecular alterations did not resemble EMT phenotype (downregulation of E-cadherin, Vimentin, ALDH, CD44, CD133, and Snail). Eventually, FR led to enhanced radiosensitivity and decreased proliferation of HT-29. Altogether, our findings suggest that FR might induce EMT and confer radioresistance in a cell context-dependent manner.     

Somatic growth of a school-aged population from Mozambique: trend and biosocial meaning

A cross-sectional study of children and adolescents from Maputo, Mozambique, was carried out in order to (1) describe the current growth status of children and adolescents from Maputo, (2) evaluate the relative status of the growth and development of youth from Maputo compared to WHO international standards, (3) assess the relationship between socioeconomic status and growth and development, and (4) assess the impact that the civil war (1980-1992) had on the health status of children and adolescents living in Maputo. The sample is composed of 2,271 subjects (1,098 boys and 1,173 girls), age 6 to 17 years. Somatic measures included height, weight, and skinfold thicknesses from which nutritional indicators were calculated and plotted against WHO norms. Subjects were divided into three groups according to their socioeconomic status. Data from a cross-sectional study done in the same areas in 1992 was used to analyze the impact of war. Beginning at 11 years, Maputo students are always shorter and weigh less than the WHO standards. BMI in boys from 11 years and in girls from 12 years is somewhat lower than the WHO norms. A social gradient is evident, favoring those students with higher socioeconomic status. Height, weight, BMI, fat mass, and lean body mass are always higher in the 1999 sample than in the 1992 study. We conclude that (1) there is a substantial difference in height and weight values of Maputo children and adolescents compared to WHO standards; (2) there is a clear advantage of being of higher socioeconomic status; (3) socioeconomic status, hygiene, and sanitation are the main factors responsible for the greater values of the 1999 sample; and (4) differences between the stature of students with higher socioeconomic status and the WHO norms are almost irrelevant. This last aspect reveals the importance of socioeconomic factors in determining the growth process, implying its importance in facilitating the "expression" of the genotypes available in the population.     

Melatonin and childbearing: Part 2. Postimplantation period

In this part of the review, we have tried to consider the dependence of the pineal hormone melatonin in human blood serum. It was established that one of the main functions of melatonin is the synchronization of all organs and the regulation of seasonal and diurnal rhythms of their physiological activity. It is confirmed that pregnancy and childbirth directly depend on the rhythm and level of melatonin secretion in the body. It was also found that melatonin maintains the appropriate proliferative level and immune status of the fetus. Disturbances in the melatonin secretion rhythm in children lead to the development of mental (stress and depression) and physiological (preeclampsia, eclampsia, fetal hypoxia, and miscarriages) pathologies. A drastic decrease in the melatonin concentration initiates the childbirth process. Therefore, the creation of conditions for maintaining a sufficient level of melatonin is required to ensure the birth of healthy offspring.     

Age at first coitus and choice of contraceptive method: preliminary report on a study of factors related to cervical neoplasia.

The incidence of cancer of the uterine cervix appears to be species-specific, thus confounding extrapolation of results from studies with experimental animals. In humans, the incidence varies more by social groups than does any other primary cancer. In a recent study, Puerto Ricans were found to have a 25 times higher risk of cervical cancer than Jews. Blacks had 4 times the risk of non-Jewish Caucasians. Age at 1st coitus (AFC) and number of coital partners have been related to increased risks. Upper socioeconomic level women have had contraceptive pills prescribed more often than others. Initial interviews and recordings of gynecologic results have been completed by the Institute for Survey Research for 25,000 American women attending large clinics and group health centers in 9 continental cities and 3 cities in Puerto Rico. Data concerning contraceptive, sexual, and reproductive history have been completed for almost 12,000. Years of education and current age have had a significant effect (p less than .001) on AFC. Gravida was also significantly related to AFC (p less than .001). The AFC of North American blacks was lower than others. Women who chose to use the pill were found to have a higher prevalence of cytologic dysplasia at the time of choice than other women. Data provide no evidence to suggest that the widespread use of oral contraceptives since the mid-1960s has been followed by increasing rates of carcinoma in situ. Other epidemiological research has failed to reveal retrospective associations between oral contraceptive use and abnormal cervical cytology. Present results are consistent with this pattern.     

Opaque-white phenotype transition: a programmed morphological transition in Candida albicans.

This paper reports that the opaque and white phenotypes of Candida albicans constitute a true high-frequency reversible transition system. The rDNA restriction fragment and orthogonal field alternating gel electrophoresis profiles of opaque and white phenotypes are indistinguishable, and a genetic marker introduced into a white strain is present in all opaque derivatives of this strain. Opaque and white derivatives appear markedly different on a bismuth indicator medium and differ in a number of other respects. We have used bismuth medium to examine the spontaneous and temperature-induced frequencies of transition from opaque to white. The temperature-induced transition from opaque to white does not occur when opaque cells are held in water.     

Melatonin and childbearing: Part 1. Preimplantation period and implantation

Melatonin is a hormone produced in terrestrial vertebrates and humans in the pineal organ, an endocrine gland. It was established that one of the major functions of melatonin is the synchronization of the function of all organs and the regulation of seasonal and diurnal rhythms of their physiological activity. The synchronization function and rhythm regulation are performed in accordance with the circadian rhythm of melatonin expression, depending on the length of day and night. Melatonin is able to influence the growth, development, and physiological activity of different types of cells, affecting the mechanisms of signaling pathways and cascades similarly to growth factors. It was confirmed that the processes of conception, pregnancy, and childbirth directly depend on the rhythm and secretion profile of the epiphyseal hormone melatonin in the body. In this review, we attempt to combine the available published data on the involvement of melatonin in various physiological processes during the preimplantation and postimplantation periods of life of the organism and its positive and negative effects at the stages of puberty.     

The number needed to treat: a clinically useful nomogram in its proper context.

The number needed to treat is a meaningful way of expressing the benefit of an active treatment over a control. It can be used either for summarising the results of a therapeutic trial or for medical decision making about an individual patient, but its use at the bedside has been impeded by the need for time consuming calculations. A nomogram has therefore been devised that will greatly simplify the calculations. Since calculations are now easy, the number needed to treat can be used to access the value of several interventions, although it does have its limitations. In particular it should not be used when it is not known whether the relative risk reduction associated with an intervention is constant for all levels of risk, or for periods of time longer than that studied in the original trials.     

The metaphase to anaphase transition: a case of productive destruction.

The metaphase to anaphase transition is a point of no return; the duplicated sister chromatids segregate to the future daughter cells, and any mistake in this process may be deleterious to both progeny. At the heart of this process lies the anaphase inhibitor, which must be degraded in order for this transition to take place. The degradation of the anaphase inhibitor occurs via the ubiquitin-degradation pathway, and it involves the activity of the cyclosome/anaphase promoting complex (APC). The fidelity of the metaphase to anaphase transition is ensured by several different regulatory mechanisms that modulate the activity of the cyclosome/APC. Great advancements have been made in this field in the past few years, but many questions still remain to be answered.     

Immunity to rubella in women of childbearing age in the United Kingdom.

In the first three years of a surveillance scheme for susceptibility to rubella in women aged 15-44 the results of over 1.3 million serological tests were collected by 80 laboratories throughout the United Kingdom. Seventy eight per cent of the results, or an average of 340,000 a year, were from pregnant women, so that just under half of all pregnant women in the United Kingdom were reported on. Eighteen per cent of results were from women tested before vaccination and the remainder were from diagnostic and other tests. Pregnant women showed an overall downward trend in susceptibility to rubella (from 4.2% at the beginning of 1984 to 3.0% at the end of 1986), and a similar decline was seen in the two other categories. Regional data showed a significant negative correlation between the proportion of pregnant women aged 15-19 who were susceptible to the virus and rate of uptake of vaccine in 14 year old schoolgirls. Women aged 25-29 were least susceptible. This form of laboratory surveillance is feasible and representative; it should be continued to monitor the effect of introducing the measles, mumps, and rubella vaccine.