Is maternal malnutrition associated with a low sex ratio at birth?

The low male/female ratio at birth in African populations has been attributed to a variety of genetic, behavioral, and environmental factors. A low sex ratio at birth has been associated with maternal malnutrition in mammals, but this issue has not been studied in humans. In this study we analyzed the relation between maternal nutritional status and sex ratio at birth in 3282 children born to 684 women from a rural African society. Short maternal stature and obesity were independently related to a low sex ratio at birth. These results are consistent with animal experiments that indicate an adverse effect of maternal malnutrition on male fetuses. The results warrant further research in this area.     

Coitus-induced ovulation and sex ratio in man

It is hypothesised that the occurence of coitus-induced ovulation could be an important factor affecting the sex ratio in human progeny. The slight preponderance of males in human sex ratio at birth, 106 : 100, could be influenced considerably by the coitus-induced occurence.     

Variation in the sex ratio in cardiovascular mortality

The favorable mortality rate of adult women compared with that of men is well known in western countries. The sex difference varies in different population groups. In Israel there is a low male:female ratio, as compared with Greece, Holland, and England and Wales. This is due to the relatively high female mortality rates in Israel. Within Israel, the Jewish population of North African origin has a relatively low male:female ratio. In this group, the marked increase in mortality due to ischemic heart disease has occurred in both women and men, in contrast to various western countries in which the male:female ratio increased during the 20th century with the rise in the death rate from ischemic heart disease, especially in middle-aged men. Social disequilibrium, especially family disorganization with its selective stressful effects on women, is suggested as an hypothesis on which to base further study in communities with a low male:female ratio associated with high mortality rates in women.     

Feed-conversion ratio of finisher pigs in the USA

Although the feed-conversion ratio is recognized as a prominent indicator of profitability for pork producers, only 212 (50.7%) of 418 producers who were asked the feed-conversion ratio for finisher pigs provided a response during the USA National Animal Health Monitoring System 1995 National Swine Study. Of these, 126 (59.4%) producers furnished a feed-conversion ratio which they characterized as having been calculated from records, while 86 (40.6%) gave a response that they characterized as estimated or guessed. Feed-conversion ratios ranged from 2.18 to 5.91 kg of feed fed for each kg of live-body weight gained during the grower/finisher phase, with a mean of 3.28 and a standard deviation of 0.52. Stepwise regression revealed the following management factors to be associated with improved feed-conversion ratios: > or = 3 different rations fed during the grower/finisher phase (P < 0.01); no rations mixed on the farm (P < 0.05); and not giving chlortetracycline in feed or water as a disease preventive or growth promotant (P < 0.01). In addition, operations where > or = 3000 pigs entered the grower/finisher-production phase during the six-month period prior to interview had a better mean feed-conversion ratio than operations where < 3000 pigs entered the grower/finisher phase (P < 0.01).     

Sex ratio at birth deviations in modern Venezuela: the Trivers-Willard effect

This study evaluates the impact of the Trivers-Willard (T-W) effect on human populations, using demographic data collected from vital registration data in Venezuela. The evaluation of the sex ratio at birth (SRB) and of fetal and infant deaths supports the existence of T-W effect in the Venezuelan population in extreme conditions. This T-W effect was observable in the SRB but not at later ages and is related to the marital status of the mother. The results indicate that the investment in females associated with environmental adversity is greater than the investment in males associated with good environmental conditions.     

How may nonresponse affect findings in organizational surveys? The tendency-to-the-positive effect.

Building on previous findings that those who hold negative attitudes toward the organization have a relatively low likelihood to participate in organizational surveys, the authors examined the impact of nonresponse on the findings of organizational surveys. An artificial example showed that if the likelihood to respond depends on one's standing on response-related variables, the scores on these latter variables will differ from those for the population, whereas between-organization differences in these variables will be underestimated. Consistent with earlier findings, our survey among employees of 96 Dutch home care organizations revealed that employees of high-response organizations reported more positive attitudes toward their work and organization than others. This underlines the importance of obtaining high response rates in organizational studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Annual variation of sex ratio in twin births and in singletons in Brazil

The annual variation of the sex ratio (SR) of 1385 twin births was analyzed and compared to that of 85909 singletons. These births referred not only to live births but also to stillbirths in two southeastern Brazilian maternity hospitals from 1984 to 1993. While the annual variation of the SR of singletons was very small, that of twin births was extremely high, due to the significant heterogeneity of the annual data. It is suggested that the large SR annual variation of the twin birth might be a consequence of the variation of male or female monozygotic twins. The hypothesis that twin births show a lower sex ratio than singletons could be supported by the present data.     

Multiple birth defects in a newborn exposed to Mycoplasma pneumoniae in utero

A newborn baby girl with progressive hydrocephalus and congenital defects of the skin and eyes was born to a mother who experienced bilateral bronchopneumonia in her first trimester. At the time of her infection, the mother's serum cold agglutinin titer was 1:128 and at delivery the mother's and baby's serum samples had complement-fixation titers to Mycoplasma pneumoniae of 1:1,024 and 1:256, respectively. At 1 week of age the baby's serum IgM value was 44 mg/100 ml (98% of cord IgM values in normal newborns range from 0 to 20 mg/100 ml). The baby died of progressive hydrocephalus, which may have had an inflammatory basis in view of the cerebrospinal fluid (CSF) protein level of 192 mg/100 ml. We realize that the significance of this association is questionable, but we believe that it is worthwhile to call the coincidence of events to the attention of others.     

Birth order and sibling sex ratio in homosexual and heterosexual non-white men

Recent studies have detected basal ganglia atrophy in clinically asymptomatic persons with the genetic mutation that causes Huntington's disease (HD). Whether reductions in caudate and putamen volume on MRI scans are associated with changes in cognitive and neurologic functioning was examined in 13 healthy adults with the IT-15 mutation. Reduced striatal volume was found to correlate with greater neurologic (largely motor) impairment, slower mental processing speed, and poorer verbal learning, although none of the participants met even liberal criteria for clinical diagnosis of HD. These correlations are strikingly similar to those observed in symptomatic HD patients, possibly reflecting the earliest manifestations of disease.     

Change in sex ratio of a Drosophila population in relation to population size

Changes in sex ratio with population size fluctuations were studied in natural and cage populations of Drosophila. It was shown that the proportion of females decreased with an increase in population size both in natural and laboratory populations. If laboratory populations were maintained on a poor diet, this effect was absent. The amplitude of number fluctuation was shown to be higher in males than in females. The possible role of density-dependent selection on sex in the control of population size dynamics is discussed.     

Multiple efflux mechanisms are involved in Candida albicans fluconazole resistance

Fluconazole-susceptible Candida albicans strains accumulated [3H]fluconazole at a rate of approximately 2 pmol/min per 10(9) cells. Fluconazole accumulation was not affected by the pretreatment of cells with sodium azide or with 2-deoxyglucose. The rate of fluconazole accumulation became saturated at high fluconazole concentrations and was not affected by the addition of ketoconazole, and there was no fluconazole accumulation in cells incubated at 4 degrees C. A fluconazole-resistant mutant of C. albicans SGY-243 was isolated following growth enrichment in fluconazole-containing medium. Cells of the mutant strain, designated FR2, showed a reduced rate of fluconazole accumulation compared with SGY-243 and were not resistant to other azole antifungal agents. The rates of fluconazole accumulation by C. albicans FR2 and the other azole-resistant strains, B59630, AD, and KB, were increased in the presence of sodium azide, suggesting that fluconazole resistance in these strains may be associated with an energy-dependent drug efflux. Fluconazole-resistant C. albicans strains all contained elevated amounts (2- to 17-fold) of mRNA encoding Cdr1, and an ATP-binding cassette-type transporter. In addition, C. albicans FR2 also contained increased amounts of mRNA encoding Benr, a major facilitator superfamily transporter. These results suggest that fluconazole enters C. albicans cells by facilitated diffusion and that fluconazole resistance may involve energy-dependent drug efflux associated with increased expression of Benr and/or Cdr1.     

Bacterial meningitis in children and adults. Changes in community-acquired disease may affect patient care

Despite improved understanding of how bacterial meningitis develops, the infection remains a potentially life-threatening emergency capable of causing significant morbidity and mortality. Since the introduction and widespread use of H influenzae type b vaccine in infancy and childhood in North America, the epidemiology of community-acquired bacterial meningitis has changed. S pneumoniae is now the most common cause in children and adults overall, although N meningitidis causes most disease in patients between ages 2 and 18 years. Broad-spectrum cephalosporins (eg, ceftriaxone, cefotaxime) are considered the agents of choice for empirical treatment of bacterial meningitis. However, use of these agents will have to be reconsidered if the incidence of invasive infection from drug-resistant S pneumoniae continues to increase. The role of adjunctive corticosteroid therapy needs to be better defined. Improved conjugate pneumococcal and meningococcal vaccines may soon make bacterial meningitis a preventable disease.