Interaction of maternal protein and carbon monoxide on pup mortality in mice: implications for global infant mortality

BACKGROUND: The United States Surgeon General declared 2005 as the "Year of Healthy Child." To improve the health of all children, we need to start before pregnancy, with their mothers. Unfortunately, protein deficiency in the diets of poor pregnant mothers in developing countries is widespread. Carbon monoxide (CO) pollution is serious public health problem in developed and developing countries. METHODS: A two-way factorial experimental design was used. Mice were maintained on 27%, 16%, 8%, or 4% protein diets. Dams were exposed to 0 ppm (control), 65 ppm, or 125 ppm CO in air, in environmental chambers for 6 hr/day during the first 2 weeks of pregnancy. Controls were also subjected to environmental chamber conditions. Food and water were available at all times. Animals were allowed to deliver, and data on pup mortality was recorded. RESULTS: Litter size was not affected by CO exposure, but was directly related to the dietary protein levels. Pup weight was inversely related to the CO exposure level, and directly related to the dietary protein levels. Pup mortality on date of birth was increased by CO exposure and was inversely related to the dietary protein levels. Pup mortality at 1 week of age was increased by CO exposure and 55% of all pups died in 125 ppm CO exposed group. Pup mortality at 1 week of age was inversely related to dietary protein levels. All pups in the 4% dietary protein and in all concentrations of CO died. All pups in the 8% protein group and in all CO concentrations died except in 125 ppm CO group. Pup mortality in the 16% dietary protein group ranged from 14.8% in 0 ppm to 36.8% in 65 ppm CO groups. Pup mortality in the 27% dietary protein group ranged from 14.3% in the 0 ppm to 41.1% in the 125 ppm CO groups. CONCLUSIONS: DATA suggest that protein deficiency and CO exposure enhance pup mortality. The protein and CO also interact to increase pup mortality in 16% and 27% protein groups. Carbon monoxide exposure, along with protein deficiency during gestation, may be contributing factors for high rates of infant mortality in developing countries. The results of the study also suggest that un-vented combustion for heating and cooking, ambient pollution, and biomass smoke may have a major impact on the health of children worldwide; and may explain the causes of high infant mortality in poor countries and some sections of the United States population.     

A joint explanation of infant and old age mortality

Journal of Biological Physics - Infant deaths and old age deaths are very different. The former are mostly due to severe congenital malformations of one or a small number of specific organs. On the...     

Harvest mortality in North American mallards: A reply to Sedinger and Herzog

Sedinger and Herzog (2012) evaluated the evidence for the impact harvest mortality may have on North American duck populations. While doing that, they questioned our review (Pöysä et al. 2004 ) and conclusion that harvest mortality in North American mallards (Anas platyrhynchos) may have shifted from compensatory to additive over the period from the 1960s to the 1980s. In this reply, we correct Sedinger and Herzog's misrepresentations of our 2004 paper and argue that our interpretations of the results published at that time have not been invalidated. © 2013 The Wildlife Society.     

Work-Related and Non-Work-Related Injury Deaths in the U.S.: A Comparative Study

This study assesses the percentage of traumatic fatalities attributable to work-related causes in the US, by cause of death and population demographics. The 1993-1998 Vital Statistics Mortality data from the National Center for Health Statistics were used. There were 848,945 traumatic fatalities (E800-E999) among the general population 16 years or older in the US during this time; of these, 32,044 were work-related accounting for 3.8% of all the fatalities. The work-related percentage varied from 62.7% for machine-related deaths to 0.7% for suicides, from 4.9% for males to 1.0% for females, from 9.8% in Alaska to 1.5% in Arizona, from 4.2% for decedents with 1 to 4 year college educations to 2.9% for decedents with high school or less, from 4.4% for races other than white and black to 2.6% for black. Mean age-at-death was 42 years for work-related vs. 48 years for non-work-related fatalities. This difference is more pronounced for deaths from falls (45 years vs. 78 years). Conversely, victims of work-related homicide were older than non-work-related (41 years vs. 33 years). A more complete understanding of the burden of traumatic fatalities attributable to work-related causes requires consideration of the total work-related percentage, causes of death, and population demographics.     

Size and mortality rates of Glossina pallidipes in the semi-arid zone of southwestern Kenya

Seasonal changes in the mean size of tsetse, Glossina pallidipes Austen, as indicated by wing vein length, were monitored during 1983-86 at Nguruman, southwestern Kenya. Changes in size of nulliparous females and wing fray category 1 males were shown to be correlated with the relative humidity 2 months before they were captured. Soil temperature when flies were in the pupal stage had much less effect. Size dependent mortality was demonstrated, with the mean size of flies emerging from pupae significantly less than that of field-caught flies. This mortality must occur at emergence, since there was no evidence of size-dependent mortality once the flies became available to the trap. Size was correlated with density-independent mortality acting on the parent population 2 months previously. It might therefore be possible to use size as an index of the intensity of such mortality. This could be useful when assessing the level of additional mortality required to suppress tsetse populations.     

The past, present and future of childhood malaria mortality in Africa

During the past few years, there has been a historic series of declarations of renewed commitment to malaria control in Africa. Whether the burden of malaria is increasing in Africa is a moot point. This article attempts to re-construct the evidence for the trends in childhood mortality as a result of Plasmodium falciparum infection over the last century in Africa.     

Ecosystem alteration modifies the relative strengths of bottom-up and top-down forces in a herbivore population

1. Ecosystem alterations can affect the abundance, distribution and diversity of plants and animals, and thus potentially change the relative strength of bottom-up (the plant resource) and top-down (natural enemies) trophic forces acting on herbivore populations. 2. The hypothesis that alterations of the forest ecosystem associated with precommercial thinning have contributed to the increased severity of outbreaks of Neodiprion abietis (Harris), a sawfly defoliator, through the reduction of trophic forces acting on N. abietis larvae, was tested using exclusion techniques. 3. The relative contributions to N. abietis larval mortality of bottom-up and top-down forces both increased with increasing levels of defoliation and were both reduced by thinning. The reduction of bottom-up and top-down forces caused a 58% mean increase in N. abietis larval survival in thinned compared with untreated stands, which is less than would be expected by the sum of the effects of thinning on each source of mortality. Evidence indicates that the partly compensatory, partly additive nature of the mortality associated with trophic forces in the system under study is responsible for this discrepancy. 4. To our knowledge, this is the first study to show the impact of ecosystem alterations on the balance between bottom-up and top-down forces acting on an eruptive herbivore population along a gradient of host-plant defoliation, and how this can lead to increased outbreak severity. It is stressed that accurate estimates of the relative contributions of bottom-up and top-down forces to mortality cannot be obtained if the additive or compensatory nature of the mortality associated with these trophic forces is overlooked.     

Causes and consequences of winter mortality in fishes

Winter mortality has been documented in a large number of freshwater fish populations, and a smaller, but increasing, number of marine and estuarine fishes. The impacted populations include a number of important North American and European resource species, yet the sources of winter mortality remain unidentified in most populations where it has been documented. Among the potential sources, thermal stress and starvation have received the most research attention. Other sources including predation and pathogens have significant impacts but have received insufficient attention to date. Designs of more recent laboratory experiments have reflected recognition of the potential for interactions among these co-occurring stressors. Geographic patterns in winter mortality are, in some cases, linked to latitudinal clines in winter severity and variability. However, for many freshwater species in particular, the effects of local community structure (predators and prey) may overwhelm latitudinal patterns. Marine (and estuarine) systems differ from freshwater systems in several aspects important to overwintering fishes, the most important being the lack of isolating barriers in the ocean. While open population boundaries allow fish to adopt migration strategies minimizing exposure to thermal stresses, they may retard rates of evolution to local environments. Geographic patterns in the occurrence and causes of winter mortality are ultimately determined by the interaction of regional and local factors. Winter mortality impacts population dynamics through episodic depressions in stock size and regulation of annual cohort strength. While the former tends to act in a density-independent manner, the latter can be density dependent, as most sources of mortality tend to select against the smallest members of the cohort and population. Most stock assessment and management regimes have yet to explicitly incorporate the variability in winter mortality. Potential management responses include postponement of cohort evaluation (to after first winter of life), harvest restrictions following mortality events and habitat enhancement. Future research should place more emphasis on the ecological aspects of winter mortality including the influences of food-web structure on starvation and predation. Beyond illuminating an understudied life-history phase, studies of overwintering ecology are integral to contemporary issues in fisheries ecology including ecosystem management, habitat evaluation, and impacts of climate change.     

The effects of health histories on stochastic process models of aging and mortality

A model of human health history and aging, based on a multivariate stochastic process with both continuous diffusion and discrete jump components, is presented. Discrete changes generate non-Gaussian diffusion with time varying continuous state distributions. An approach to calculating transition rates in dynamically heterogeneous populations, which generalizes the conditional averaging of hazard rates done in fixed frailty population models, is presented to describe health processes with multiple jumps. Conditional semi-invariants are used to approximate the conditional p.d.f. of the unobserved health history components. This is useful in analyzing the age dependence of mortality and health changes at advanced age (e.g., 95 +) where homeostatic controls weaken, and physiological dynamics and survival manifest nonlinear behavior.     

Urban and rural differences in mortality and causes of death in historical Poland

The purpose of this paper is to document and interpret urban-rural differences in mortality in the past. To this end, we used data on mortality in Wielkopolska, Poland, in the 19th century and at the beginning of the 20th century. The data on mortality in rural areas (N = 1,173,910 deceased), small towns (N = 573,903 deceased), and Poznań, the capital of the Wielkopolska region (N = 86,352 deceased), were gathered from original Prussian statistical yearbooks (Preussische Statistik). Causes of death were also analyzed (rural areas, N = 449,576 deceased; small towns, N = 238,365 deceased; Poznań, N = 61,512 deceased). Mortality measures such as crude death rate (CDR), infant death rate (IDR), and neonatal and postneonatal death rates were calculated. Life tables were constructed for both stationary and stable population models and measures of the opportunity for natural selection calculated (Crow's index I(m), potential gross reproduction rate R(pot), and biological state index I(bs)). Relative frequencies of leading causes of death were computed. Stratification depending on the place of residence was evident in all mortality measures as well as in the values of the life tables and the measures of the opportunity for natural selection, but it was reverse of what is observed today in developed countries. In Poznań (a large industrial city), the mortality situation was the least favorable. It was caused by large population density, lack of water supply and sewage systems (up to 1896), and bad working conditions. The values of CDR ranged between 26.89-31.46, and IDR between 190.6-280.5. Newborn life expectancy (for a stable population model) was 31.6 years, I(m) = 0.79, R(pot) = 0.85, and I(bs) = 0.47. The most common causes of death were tuberculosis, other diseases of the respiratory and circulatory systems, dysentery and diarrhea, and cancer. These diseases were less common in rural areas, so they had the most favorable values of mortality measures (CDR between 22.87-27.32, IDR between 181.8-219.4, life expectancy of newborn e(0) = 42.12, I(m) = 0.55, R(pot) = 0.93, I(bs) = 0.60). Infectious diseases (other than tuberculosis), frailty at birth, and frailty in old age were the most frequent causes of death in rural areas. Small towns (population <20,000) had a mortality intermediate between city and rural areas.     

Density- and size-dependent mortality of a settling coral-reef damselfish (<Emphasis Type="Italic">Pomacentrus moluccensis</Emphasis> Bleeker)

Density-dependent mortality may regulate many populations, but due to an offshore larval phase in benthic marine organisms, it is often difficult to quantify the effects of mortality of arriving individuals. We added approximately 600 recruit-sized individuals onto coral reef that parallels patterns in naturally settling fish. Strong, positive density-dependent mortality occurred 3 days, 1–2 weeks, and 4 months after release. Since our study species was patchily distributed, we estimated both mean group size and overall density in a transect. Mortality was more strongly related to mean group size than overall density in a transect, indicating that recruit patchiness was important. Cohesive groups may suffer higher mortality than those spread over larger areas, even if overall density of the latter is greater. Aggregative responses of predators may occur in response to larger groups, so may have contributed to positive density-dependent mortality. Increased conspicuousness to predators and congeneric aggression are additional factors that may vary positively with group size. Tagging of recruits showed migration within but not between transects, so persistence was tantamount to survival. Standard otolith back-calculation techniques employed to reconstruct original size of tagged recruits that persisted 4 months after additions indicated that mortality was also size-dependent. Size-dependent mortality was apparent at the site with the highest mortality but not at the site with the lowest mortality, resulting in different mean body sizes of recruits between sites. Size-dependent mortality may influence estimation of growth and lead to onset of size-based maturity in these fish. Strong, positive density-dependent mortality may regulate recruitment, and if coupled with size-dependent mortality, may increase maturity rate, adding to reproductive schedules of those that survive.     

Bird predation as a sex- and size-selective agent of the arboreal spider Pityohyphantes phrygianus

1. The solitary sheetweb spider Pityohyphantes phrygianus (Araneae: Linyphiidae) lives in canopies of coniferous trees. Earlier studies in Scandinavia have shown that bird predation affects the spider abundance negatively.
2. In a large-scale, 2-year field experiment, passerine birds were excluded from foraging on spruce branches. The experimental branches were net-enclosed, which prevented bird predation but left spiders free to leave and enter. Samples were taken in the autumn and spring for 2 years.
3. Removal of bird predation increased the mean number of subadult P. phrygianus per branch between 2·1 and 10·6 times the control number for each sex. Bird predation had approximately similar effects on the sexes, except in the second experimental spring when males were affected twice as much as females, and there was a significantly lower proportion of males on control branches exposed to bird predation than on net-enclosed branches.
4. The mean size of females was larger on net-enclosed branches than on controls in both spring samples. In males, this was the case in the first spring sample only.
5. This study shows that there are also mortality costs for both sexes associated with large size in the non-mating season. In certain winters, however, there is an additional mortality risk to males, presumably caused by a higher activity level than in females.     

Early childhood stress and adult age mortality--a study of dental enamel hypoplasia in the medieval Danish village of Tirup

This study explores how linear enamel hypoplasia (LEH) affects mortality in the village of Tirup (A.D. 1150-1350), Denmark. Data consist of information on 583 skeletons aged 1 year or more. Three partly overlapping subsamples were defined. (1) 104 skeletons of young children aged 1-6 years and 120 skeletons of adults giving information on LEH. (2) 458 skeletons aged 6 years or more. (3) 109 adult skeletons (aged 20 years or more) that provided transition analysis age estimates, sex assessments, and LEH information. Of the 109 skeletons in Subsample 3, 60 had no and 49 had at least one LEH. In Subsample 1, it was found that the case fatality rate for episodes potentially leading to LEH dropped from over 0.5 in 1-year olds to around 0.1 in 3-5-year olds. Only models with heterogeneity of frailty could describe late childhood and adolescent mortality. Further, it was shown that only a model with continuously varying frailty preserved heterogeneity to adulthood. Among young adult females and males in all adult ages, people with LEH experienced a higher mortality than people without it. Among males, the mortality rate ratio (MRR) was 2.28. The analyses indicate that the MRR gives an unbiased estimate for the extra risk of dying for adult males with LEH. The values of the case fatality rates for young children might be slightly biased upward because of a higher than average number of older children and adolescents dying with LEH.     

Relationships between ovulation rate and embryonic and placental characteristics in multiparous sows at 35 days of pregnancy

The objective of this study was to investigate relationships between ovulation rate (OR) and embryonic and placental development in sows. Topigs Norsvin^R sows (n=91, parity 2 to 17) from three different genetic backgrounds were slaughtered at 35 days of pregnancy and the reproductive tract was collected. The corpora lutea (CL) were counted and the number of vital and non-vital embryos, embryonic spacing (distance between two embryos), implantation length, placental length, placental weight and embryonic weight were assessed. The difference between number of CL and total number of embryos was considered as early embryonic mortality. The number of non-vital embryos was considered as late mortality. Relationships between OR and all other variables were investigated using two models: the first considered parity as class effect (n=91) and the second used a subset of sows with parities 4 to 10 (n=47) to analyse the genetic background as class effect. OR was significantly affected by parity (P<0.0001), but was not affected by the genetic background of the sows. Parity and genetic background did not affect embryonic and placental characteristics at 35 days of pregnancy. OR (varying from 17 to 38 CL) was positively related with early embryonic mortality (β=0.49±0.1 n/ovulations, P<0.0001), with late embryonic mortality or number of non-vital embryos (β=0.24±0.1 n/ovulations, P=0.001) and with the number of vital embryos (β=0.26±0.1 n/ovulations, P=0.01). However, dividing OR in four classes, showed that the number of vital embryos was lowest in OR class 1 (17 to 21 CL), but not different for the other OR classes, suggesting a plateau for number of vital embryos for OR above 22. There was a negative linear relationship between OR and vital embryonic spacing (β=−0.45±0.1 cm/ovulation, P=0.001), implantation length (β=−0.35±0.1 cm/ovulation, P=0.003), placental length (β=−0.38±0.2 cm/ovulation, P=0.05) and empty space around embryonic-placental unit (β=−0.4±0.2 cm/ovulation, P=0.02), indicating uterine crowding. Further analyses showed that effects of OR on embryonic and uterine parameters were related with the increase in late mortality and not early embryonic mortality. Therefore, we conclude that a high OR results in an moderate increase in the number of vital embryos at day 35 of pregnancy, but compromises development in the surviving embryonic/placental units, suggesting that the future growth and survival of the embryos might be further compromised.     

The Body Mass Index-Mortality Relationship in White and African American Women

Objective : To examine the association of body mass index to all-cause and cardiovascular disease (CVD) mortality in white and African American women. Research methods and procedures : Women who were members of the American Cancer Society Prevention Study I were examined in 1959 to 1960 and then followed 12 years for vital status. Data for this analysis were from 8,142 black and 100,000 white women. Body mass index (BMI) was calculated from reported height and weight. Associations were examined using Cox proportional hazards modeling with some analyses stratified by smoking (current or never) and educational status (less than complete high school or high school graduate). Results : There was a significant interaction between ethnicity and BMI for both all-cause (p<0.05) and CVD mortality (p<<0.001). BMI (as a continuous variable) was associated with all-dause mortality in white women in all four groups defined by smoking and education. In black women with less than a high school education, there were no significant associations between BMI mortality. For high school-educated black women, there was a significant association between BMI and all-cause mortality. Among never smoking women with at least a high school education, models using the lowest BMI as the reference indicated a 40% higher risk of all-cause mortality at a BMI of 35.9 in black women vs. 27.3 in white women. Discussion : The impact of BMI on mortality was modified by educational level in black women; however, BMI was a less potent risk factor in black women than in white women in the same category of educational status.     

Effect of exposure to Echinostoma itliei miracidia on growth and survival of young Biomphalaria glabrata snails

Kuris A. M. 1980. Effect of exposure to Echinostoma liei miracidia on growth and survival of young Biomphalaria glabrata snails. International Journal for Parasitology10: 303–308. Exposure to miracidia of Echinostoma liei resulted in increased mortality and reduced growth of 1–2 mm albino Biomphalaria glabrata snails whether or not the snails became infected. Growth rates for infected and exposed but uninfected snails were significantly more variable than growth rates of unexposed snails. Retarded growth and increased mortality were detected as rapidly as seven to nine days after exposure. Neither growth nor survivorship of 4–6 mm snails was altered upon exposure to or infection by E. liei.     

东江鲤鱼种群动态及其最大持续渔获量的研究

本文研究东江鲤鱼的种群动态并进行渔业生物学分析。用Von Bertalanffy生长方程可以表达东江鲤鱼体长、体重与年龄的关系,L=39.308R-42.611,L_t=851[1-e(-0.173(t 0.0394))]W_t=19171.5[1-e~(-0.173(t 0.0394))]~3。通过渔获物统计资料计算种群的自然死亡率D=0.27和捕捞死亡率E=0.25,并分析比较产卵力及产卵群体的结构类型。通过比较各种捕捞强度和最小捕捞规格的不同的总渔获量和群体的相对数量,提出获得持续渔获量的捕捞强度F=0.35及最小捕捞年龄t=2。     

Selective mortality and the anthropometric status of children in low- and middle-income countries

Despite a close relationship between the childrens’ anthropometric status and mortality rates, the highest mortality rates are concentrated in sub-Saharan Africa, while the lowest anthropometric indicators, in particular the height-for-age z-scores, are concentrated in South Asia. This discrepancy should, however, be expected to decrease when one accounts for the survivorship bias, i.e. selective mortality. We analyse whether the survivorship bias can explain these observed differences in three standard anthropometric indicators (stunting, underweight and wasting) by using individual data of children from six waves of Demographic and Health Surveys for a large cross-section of 37 low- and middle-income countries between 1991 and 2016. We use both a matching approach and semi-parametric regression to estimate the values for the anthropometric status of deceased children. The results are twofold: first, both methods reveal that the imputed values for the anthropometric indicators are, on average, between 0.10 and 0.25 standard deviations lower than the observed anthropometric indicators. Second, since the share of deceased children in our sample is below ten per cent, the contribution of the anthropometric status of deceased children to overall anthropometric indicators is small and therefore only influences it marginally.