Viral determinants of age-dependent virulence of Sindbis virus for mice.

Many alphaviruses cause more severe disease in young animals than in older animals. The age-dependent resistance to severe disease is determined primarily by maturation of the host, but strains of virus can be selected that overcome the increased resistance of mature animals. Sindbis virus (SV) strain AR339 causes fatal encephalitis in newborn mice and nonfatal encephalitis in weanling mice, whereas NSV, a neuroadapted strain of SV, causes fatal encephalitis in weanling as well as newborn mice. We have previously shown that the E2 glycoprotein of NSV contained His-55, whereas AR339 E2 had Gln-55 (S. Lustig, A. C. Jackson, C. S. Hahn, D. E. Griffin, E. G. Strauss, and J. H. Strauss, J. Virol. 62:2329-2336, 1988) and that SV with E2 containing Gly-172 was more virulent for newborn mice than SV with E2 containing Arg-172 (P. C. Tucker and D. E. Griffin, J. Virol. 65:1551-1557, 1991). Here we tested the virulence for both newborn and older mice of SV containing a number of different amino acids at E2 position 55 (His, Gln, Lys, Arg, Glu, Gly) in combination with both Gly-172 and Arg-172. All the viruses were virulent for newborn mice, but the residues at both 55 and 172 influenced the virulence of the virus, and there were differences in virulence observed among the various viruses. However, only viruses with His-55 were fully virulent for 14-day-old mice, and this virulence was independent of the residue at position 172. Virus with Lys-55 was virulent for 7-day-old mice, although slightly attenuated relative to His-55. Viruses with His-55 grew more rapidly and to higher titer in the brains of 7- and 14-day-old mice, in N18 neuroblastoma cells, and in BHK cells. Our data suggest that His-55 is important for neurovirulence in older mice and acts by increasing the efficiency of virus replication.     

Reproductive strategy of an invasive thistle: effects of adults on seedling survival

Invasive species are known for their ability to form monocultures that exclude native species, yet intraspecific interactions among invasives have not been well studied. Cynara cardunculus (L.) is an invasive perennial thistle that establishes high-density populations in coastal California grasslands. We examined the natural distribution of C. cardunculus seedlings in an established population and found that nearly 100% of seedlings grew within 2 m of adults despite an expected distribution peak at 3 m from source plants based on measured dispersal distances. We then investigated the role of mature plants in seedling survival and establishment with regard to live vegetation, litter, and seedling distance by planting seedlings at increasing distances around adults and applying removal treatments to the focal adult rosettes. We applied control (no removal), adult rosette removal (live leaves), litter removal (dead leaves), and adult rosette plus litter removal (all aboveground plant material) treatments. Seedlings experienced a higher rate of survival, measured by senescence date, and establishment, measured by return rate the following year, with all adult rosette removal treatments. Inhibition by adult rosettes was reduced with distance to 60–80 cm from the rosette, and there was little effect of adult plants between 80 and 200 cm. These results suggest that adult rosettes may inhibit conspecific seedlings at very close distances but provide a favorable environment for seedlings within nearby interspaces. This pattern may contribute to the creation and maintenance of high-density populations in C. cardunculus. Land managers seeking to control this species may improve long-term effectiveness by expanding management efforts to include a 2 m radius around adult plants and treating within 5 months of seedling emergence to prevent recruitment rather than treating adults alone.     

Postpartum amenorrhoea in Ethiopia: The role of weaning,child death,and socioeconomic factors

Abstract

Using data from the 1990 National Family and Fertility Survey (NFFS) and employing discrete‐time hazards models, we examine the effect of weaning, child death, and socioeconomic factors on postpartum amenorrhoea in Ethiopia. The results show that 91 in every 100 mothers breastfed their child for at least 6 months. The median duration of breastfeeding stands at 18 months, and amenorrhoea lasts for a median duration of 12 months. Significant variations in breastfeeding and amenorrhoea duration are also observed among the different categories of breastfeeding women. The median duration of breastfeeding for lactating women is 24 months, 6 months for those who weaned, and 2 months for those whose child died. The median duration of postpartum amenorrhoea is 14 months for breastfeeding women, 12 months for those who weaned, and 6 months for those whose child died. Discrete‐time hazard models reveal that child death has the strongest effect on the resumption of menses. Net of other factors, the risk of returning to menses increased 3 times for mothers whose child died. The effect of child death, however, decreases over time. Weaning also has a significant positive effect; and, like child death, its effect diminishes as time passes. The study further shows significant differences in the risk of returning to postpartum menses by socioeconomic characteristics of the women, even though they are breastfeeding.     

Health care utilization, socioeconomic factors and child health in India

This paper models the proximate determinants of height, weight and haemoglobin concentration of over 25,000 Indian children using data from the National Family Health Survey-3. The effects of public and private health care service utilization, food consumption patterns and maternal health status on child health were investigated in a multidisciplinary framework. Methodological issues such as potential endogeneity of explanatory variables and the appropriateness of combining height and weight as the body mass index were tackled. The results from models for children's heights and weight showed beneficial effects of child vaccinations against DPT, polio and measles, and negative effects of not utilizing government health facilities. The models for children's haemoglobin concentration indicated beneficial effects of food consumption patterns and treatment against intestinal parasites. The results provide several insights for improving child health in India.     

Cigarette smoking by socioeconomic group,sex, and age: effects of price,income, and health publicity.

OBJECTIVE--To assess effects of price, income, and health publicity on cigarette smoking by age, sex, and socioeconomic group. DESIGN--Econometric multiple regression analysis of data on cigarette smoking from the British general household survey. SUBJECTS--Random sample of adult population in Britain interviewed for biennial general household surveys 1972-90. MAIN OUTCOME MEASURES--Changes in cigarette consumption and prevalence of smoking. RESULTS--Price elasticities of demand for cigarettes (percentage change in cigarette consumption for a 1% change in price) were significant at -0.5 (95% confidence interval -0.8 to -0.1) for men and -0.6 (-0.9 to -0.3) for women, were highest in socioeconomic group V (-1.0 for men and -0.9 for women), and lowest (not significantly different from zero) in socioeconomic groups I and II. The gradient in price elasticities by socioeconomic group was significant for men (F = 5.6, P = 0.02) and for women (F = 6.1, P = 0.02). Price was a significant factor in cigarette consumption by age for women in every age group and for men aged 25-34. Cigarette consumption by young men aged 16-34 increased with income. There was a significant decrease in smoking over time by women in socioeconomic groups I and II and by men in all age and social groups except socioeconomic group V attributable to health publicity. Price significantly affected smoking prevalence in socioeconomic group V (-0.6 for men and -0.5 for women) and for all women (-0.2). CONCLUSIONS--Men and women in lower socioeconomic groups are more responsive than are those in higher socioeconomic groups to changes in the price of cigarettes and less to health publicity. Women of all ages, including teenagers, appear to have been less responsive to health publicity than have men but more responsive to price. Response to health publicity decreased linearly with age. Real price increases in cigarettes could narrow differences between socioeconomic groups in smoking and the related inequalities in health, but specific measures would be necessary to ameliorate effects on the most deprived families that may include members who continue to smoke. The use of a policy to steadily increase cigarette tax is likely to help achieve the government''s targets for smoking and smoking related diseases.     

Reproductive investment and seedling survival of the mast-fruiting rain forest tree,Microberlinia bisulcata A. chev.

In the southern part of Korup National Park, Cameroon, the mast fruitingtree Microberlinia bisulcata occurs as a codominant ingroves of ectomycorrhizal Caesalpiniaceae within a mosaic of otherwisespecies-rich lowland rain forest. To estimate the amount of carbon andnutrientsinvested in reproduction during a mast fruiting event, and the consequentialseed and seedling survival, three related field studies were made in 1995.Theseprovided a complete seed and seedling budget for the cohort. Seed productionwasestimated by counting woody pods on the forest floor. Trees produced on average26,000 (range 0–92,000) seeds/tree, with a dry mass of 16.6kg/tree. Seeds were contained in woody pods of mass 307kg/tree. Dry mass production of pods and seeds was 1034 kgha^–1, equivalent to over half (55%) of annual leaflitterfall for this species, and contained 13% of the nitrogen and 21% of thephosphorus in annual leaf litterfall. Seed and young-seedling mortality wasinvestigated with open quadratsand cages to exclude vertebrate predators, at two distances from the parenttree. The proportion of seeds on the forest floor which disappeared in thefirst6 wk after dispersal was 84%, of which 26.5% was due to likelyvertebrate removal, 36% to rotting, and 21.5% to other causes. Vertebratepredation was greater close to the stem than 5 m beyond the crown(41 vs 12% of seeds disappearing) where the seed shadow was less dense.Previousstudies have demonstrated an association between mast years at Korup and highdry-season radiation before flowering, and have shown lower leaf-litterfallphosphorus concentrations following mast fruiting. The emerging hypothesis isthat mast fruiting is primarily imposed by energy limitation for fruitproduction, but phosphorus supply and vertebrate predation are regulatingfactors. Recording the survival of naturally-regeneratingM. bisulcata seedlings (6-wk stage) showed that 21% ofseedlings survived to 31 mo. A simple three-stage recruitment model wasconstructed. Mortality rates were initially high and peaked again in each ofthenext two dry seasons, with smaller peaks in the two intervening wet seasons,these latter coinciding with annual troughs in radiation. The very poorrecruitment of M. bisulcata trees in Korup, demonstratedinprevious investigations, appears not to be due to a limitation in seed oryoung-seedling supply, but rather by factors operating at theestablished-seedling stage.     

Low-birth-weight effects of demographic and socioeconomic variables and prenatal care in Pima County,Arizona.

Low birth weight is the major determinant of infant mortality. Continuing declines in infant mortality in the United States are due to the use of neonatal intensive care services; less progress has been made toward preventing low birth weight. I examined how the demographic, socioeconomic, and health services use variables affected rates of low birth weights in Pima County, Arizona, in 1985. Women at greatest risk of having the smallest infants were those younger than 21 years and those with fewer than 6 prenatal visits. Nulliparous women with fewer than 6 prenatal visits showed a still greater risk of having an infant of low birth weight. Women without medical insurance coverage had babies with the lowest mean birth weights, as well as significantly fewer prenatal visits. As the number of uninsured in the United States increases, the effect of lack of insurance among pregnant women becomes increasingly important. To prevent low-weight births, comprehensive maternity care services must be available to all pregnant women regardless of ability to pay.     

Correlates and determinants of child anthropometrics in Latin America: background and overview of the symposium.

In Latin America and the Caribbean (LAC) about one in six children under 5 years of age--or about 9 million children--suffer from longer-run undernourishment reflected in stunting. This paper introduces, places in perspective and presents a common micro analytical framework for the seven papers in this symposium that investigate the household and community determinants of child malnourishment in eight countries in LAC. These papers are the outcomes of a research project supported by the Inter-American Development Bank (IDB) Research Department Latin American and Caribbean Research Network Project on "Child Health, Poverty and the Role of Social Policies" in 2003-2004.     

The health hazards of unemployment and poor education: the socioeconomic determinants of health duration in the European Union.

The effect of socioeconomic status on the likelihood that an individual enters a period of poor health is examined using an Accelerated Failure Time methodology. This study employs data from the European Community Household Panel for the years 1994-2002 across 13 European countries, using the Physical and Mental Health Problems, Illnesses and Disabilities measure of physical health. Some socioeconomic status indicators do impact on the length of time an individual remains in good health - these being unemployment, which has a negative effect, and education, which has a positive effect - but others, such as income, have far less of an impact. Age and gender effects are also found.     

Photoinhibition in Vitis californica: interactive effects of sunlight, temperature and water status

Abstract. In a series of factorial experiments with cultivated Vitis californica Benth. (California wild grape) growth outdoors in full sun, we examined the effects of sunlight, temperature and water status on net CO₂ uptake and PSH chlorophyll fluorescence at 77K. Exposure to either high light or high temperature caused reductions in PSH activity followed by partial or complete overnight recovery. Upon simulataneous exposure to high light and high temperature, PSH inhibition was severe and persistent. The maximum chlorophyll fluorescence (F_M) and the ratio of variable to maximum fluorescence (F_v/F_M) differed in their responses to combinations of light and temperature. At both low and high light. F_M declined with increasing temperature over a wide temperature range, while F_v/F_M exhibited a similar sensitivity to temperature only at high light. Net CO₂ uptake declined by mid-afternoon and recovered by the next morning in most leaves, regardless of incident light or temperature. However, high-light leaves exhibited severe and lasting declines if temperatures exceeded 45°C. Water-stressed leaves exposed to high light exhibited greater reductions of net CO₂ uptake than water-stressed leaves exposed to low light. However, the degree of light-dependent decline in PSH fluorescence (F_M and F_v/F_M) did not vary with water status, indicating that reduced PSH activity was not a primary cause of reduced carbon gain during water stress.     

Reproductive performance,growth, and survival of selected and wild X selected channel catfish

Summary Wild (W) and selected (S) strains of channel catfish (Ictalurus punctatus) were crossed to attempt to introduce genes from wild stocks into a domesticated stock without loss of growth or survival performance. W strain broodfish were from the Kaskaskia River in Illinois and had no history of artificial selection. The S strain broodfish had undergone two generations of selection for multiple-traits since 1974 and had become adjusted to tank, cage, and pond culture conditions. Females and males from both strains were paired in individual spawning pens in all possible combinations and the 19 subsequent egg masses were artificially incubated. The 15 SXS, 6 WXS and 9SxW crosses produced 10, 3 and 6 egg masses, respectively. None of the 7 WXW pairs spawned. The fish density was standardized to two tanks of 500 in each full-sib family at 4 weeks of age and 200 in each at 12 weeks of age. Domesticated and crossbred fish did not differ in spawn characteristics or 4-week body weight but domesticated catfish grew progressively faster than crossbreds and were 55% heavier and 16% longer by 40 weeks of age. No survival differences were observed among the three genetic groups. A 9-week cage test which followed the tank culture also indicated that domesticated fish were superior to crossbreds in body weight, total length, condition factor, and carcass weight. These results indicated that a single WxS cross did not establish improved gene combinations without loss of growth performance.     

Insurance and other socioeconomic determinants of elderly longevity in a Costa Rican panel

Official figures show that life expectancy in Costa Rica is longer than in the United States (US), in spite of the fact that per capita health expenditure is only one-tenth that of the US. To check whether this is for real and to explore some of its determinants, 900 Costa Ricans aged 60+ were followed from 1984 to 2001. Follow-up household visits were made, deaths were tracked in the national death registry, and survival status in the voting registry was double-checked. In addition, the survivors were contacted in 2002. Two-thirds of the panel had died by December 2001. Kaplan-Meier curves, life tables and Cox regression were used to analyse the panel's survival. Mortality in the panel was slightly higher than the Costa Rican average and similar to that in the US, confirming the exceptional longevity of Costa Ricans. Survival was substantially lower among unmarried men and individuals with limited autonomy at the beginning of the study. The effect of socioeconomic status is weak. Insurance effects seem to be confounded by selection biases.     

The interactive effects of irradiance and photoperiod on Chara vulgaris L.: concerted responses in morphology, physiology, and reproduction

Both the single and interactive effects of irradiance and photoperiod on a worldwide charophyte species, Chara vulgaris L., were investigated in a greenhouse experiment. Under high light intensity, plants exhibited shortened shoot, compact canopy and low Chl a/Caro. In contrast, elongated shoot, expanded canopy and low Chl a/Chl b corresponded to low light intensity. In addition, both ash mass ratio and relative growth rate (RGR) were positively related to light intensity. The effect of photoperiod on plants was relatively complex. Although photoperiod did not affect morphological characters, an increased photoperiod significantly decreased Chl a/Chl b and Chl a/Caro ratios. Two-way analysis of variance (ANOVA) analysis indicated that significant interaction of irradiance and photoperiod was present on ash mass ratio, RGR, Chl a/Chl b, Chl a/Caro and Chl (a + b)/Caro ratios. The high RGR found for 50% sunlight, L:D 16:8 (50/16) conditions along with the significant interaction of irradiance and photoperiod on RGR indicated that the effect of irradiance was more important than photoperiod for plant growth. And finally, both irradiance and photoperiod had positive effects on the emergence of sex organs (♂♀) and the maturation of oospores, except that increased photoperiod did not accelerate the maturation of oospores. In summary, for both plant growth and reproduction, C. vulgaris was able to acclimate morphologically and physiologically to different irradiance levels and photoperiods. This study can partly explain the broad geographic distribution of C. vulgaris. Handling editor: S. M. Thomaz     

Reproductive behaviour in survival: a comparison between wild and domestic sheep

The recorded behaviour of wild species of Ovis at the beginning of the breeding season supports the proposal that mating is synchronized by the 'ram effect', a phenomenon already described in domestic sheep. Animals separate into exclusive male flocks, and flocks of females and young animals for most of the year. They reunite just before the rutting season. At lambing there appear to be behavioural mechanisms that ensure that ewes lamb in close proximity to one another. It is hypothesized that these behavioural characteristics of wild sheep help protect the newborn and that much of the reproductive and maternal behaviour of domestic sheep may be traced to comparable behaviour in wild species.     

Patients with aortic stenosis referred for TAVI: treatment decision, in-hospital outcome and determinants of survival

Aims

To assess treatment decision and outcome in patients referred for transcatheter aortic valve implantation (TAVI) in addition to predictive factors of mortality after TAVI.

Methods

Three-centre prospective observational study including 358 patients. Endpoints were defined according to the Valve Academic Research Consortium.

Results

Of the 358 patients referred for TAVI, TAVI was performed in 235 patients (65%), surgical aortic valve replacement (AVR) in 24 (7%) and medical therapy (MT) in 99 (28%). Reasons to decline TAVI in favour of AVR/MT were patient preference (29%), peripheral vascular disease (15%) and non-severe aortic stenosis (11%). The logistic EuroSCORE was significantly higher in patients who underwent TAVI and MT in comparison with those undergoing AVR (19 vs. 10%, p = 0.007). At 30 days, all-cause mortality and the combined safety endpoint were 9 and 24% after TAVI and 8 and 25% after AVR, respectively. All-cause mortality was significantly lower in the TAVI group compared with the MT group at 6 months, 1 year and 2 years (12% vs. 22%, 21% vs. 33% and 31% vs. 55%, respectively, p < 0.001). Multivariable analysis revealed that blood transfusion (HR: 1.19; 95% CI: 1.05–1.33), pre-existing renal failure (HR: 1.18; 95% CI: 1.06–1.33) and STS score (HR: 1.06; 95% CI: 1.02–1.10) were independent predictors of mortality at a median of 10 (IQR: 3–23) months after TAVI.

Conclusions

Approximately two-thirds of the patients referred for TAVI receive this treatment with gratifying short- and long-term survival. Another 7% underwent AVR. Prognosis is poor in patients who do not receive valve replacement therapy.     

Mother's death and child survival: the case of early Quebec

The aim of this paper is to account for the effect of mother's death on child survival in a historical population. Using comprehensive data on the early French Canadian population of Quebec, evidence is provided for a higher risk of dying for motherless children that remains significant over all childhood and long after the death of the mother. The specific effect of the loss of maternal care was estimated by comparing mortality before and after mother's death, furnishing a means to control for family heterogeneity. No differential in investment between genders was detected before age 3, but older girls suffered a three-fold higher susceptibility to mother's death than their male counterparts. This suggests that grown-up girls assuming the responsibilities of the missing mother had a lower chance of survival.