Culled males,infant mortality and reproductive success in a pre-industrial Finnish population

Theoretical and empirical literature asserts that the sex ratio (i.e. M/F) at birth gauges the strength of selection in utero and cohort quality of males that survive to birth. We report the first individual-level test in humans, using detailed life-history data, of the ‘culled cohort’ hypothesis that males born to low annual sex ratio cohorts show lower than expected infant mortality and greater than expected lifetime reproductive success. We applied time-series and structural equation methods to a unique multigenerational dataset of a natural fertility population in nineteenth century Finland. We find that, consistent with culled cohorts, a 1 s.d. decline in the annual cohort sex ratio precedes an 8% decrease in the risk of male infant mortality. Males born to lower cohort sex ratios also successfully raised 4% more offspring to reproductive age than did males born to higher cohort sex ratios. The offspring result, however, falls just outside conventional levels of statistical significance. In historical Finland, the cohort sex ratio gauges selection against males in utero and predicts male infant mortality. The reproductive success findings, however, provide weak support for an evolutionarily adaptive explanation of male culling in utero.     

Risk of cancer in Finnish children living close to power lines.

OBJECTIVE--To investigate the risk of cancer in children living close to overhead power lines with magnetic fields of > or = 0.01 microteslas (microT). DESIGN--Cohort study. SETTING--The whole of Finland. SUBJECTS--68,300 boys and 66,500 girls aged 0-19 years living during 1970-89 within 500 m of overhead power lines of 110-400 kV in magnetic fields calculated to be > or = 0.01 microT. Subjects were identified by record linkages of nationwide registers. MAIN OUTCOME MEASURES--Numbers of observed cases in follow up for cancer and standardised incidence ratios for all cancers and particularly for nervous system tumours, leukaemia, and lymphoma. RESULTS--In the whole cohort 140 cases of cancer were observed (145 expected; standardised incidence ratio 0.97, 95% confidence interval 0.81 to 1.1). No statistically significant increases in all cancers and in leukaemia and lymphoma were found in children at any exposure level. A statistically significant excess of nervous system tumours was found in boys (but not in girls) who were exposed to magnetic fields of > or = 0.20 microT or cumulative exposure of > or = 0.40 microT years. CONCLUSIONS--Residentia magnetic fields of transmission power lines do not constitute a major public health problem regarding childhood cancer. The small numbers do not allow further conclusions about the risk of cancer in stronger magnetic fields.     

Birth spacing and child mortality in a Caribbean population.

Ten independent variables were used to predict death before the first birthday for 4411 births that took place from 1878 to 1976 to 978 women of native ancestry on the island of St. Barthélemy. Significant predictors of death include the death of the mother within a year, the birth year, multiple birth, whether the preceding child also died before 1 year of age, and whether the next child was conceived before the index child was 1 year old. Unlike most prior studies, birth-spacing variables were only weakly related to death in the first year. The relative absence of contraceptive techniques to control birth spacing in the study population and the use of vital records rather than survey data distinguish this project from others and may account at least partly for the unusual findings.     

Polymorphism of red cell S-formylglutathione hydrolase in a Finnish population

Red cell hemolysates from a Finnish population sample (n = 242) were fractionated by isoelectric focusing on polyacrylamide gel, and S-formylglutathione hydrolase (EC 3.1.2.12) was located by activity staining. Polymorphism, which is probably genetically determined, was found. The samples from most persons studied gave one major enzyme band, whereas for 6 persons three enzyme bands were found. The enzyme is a dimer, and the polymorphism observed appears to result from two alleles, FGH1 and FGH2 at an autosomal locus. The frequency found for FGH1 was 0.988.     

Unemployment and mortality among Finnish men, 1981-5.

OBJECTIVE--To ascertain whether, after controlling for several relevant background variables simultaneously, unemployment is related to mortality and to assess whether this relation is causal or whether unhealthy people are more likely to become unemployed. DESIGN--Prospective study of mortality in Finland during 1981-5 based on 1980 census data on 30-54 year old wage earner men and with particular attention to unemployment in the year before the census. SETTING--Research project at the University of Helsinki. SUBJECTS--All wage earner men in Finland aged 30-54 at the 1980 census. MAIN OUTCOME MEASURES--Causes of death during 1981-5 and duration of unemployment in the year before the census. Background variables controlled for were age, socioeconomic state, marital state, and health. The data were analysed by log linear regression models. RESULTS--During the study period 1981-5, which covered almost 2.7 million person years, there were 9810 deaths. After controlling for all background variables relative total mortality among unemployed versus employed men was 1.93 (95% confidence interval 1.82 to 2.05). The excess mortality was highest in accidental and violent causes of death (relative mortality 2.51; 95% confidence interval 2.28 to 2.76). For circulatory diseases the relative death rate was 1.54 (95% confidence interval 1.40 to 1.70), but among neoplasms only lung cancer was associated with excess mortality. Selection for unemployment based on age, socioeconomic state, and marital state was evident but no such selection was detected based on health. Effects of unemployment on mortality were more pronounced with increasing duration of unemployment. CONCLUSIONS--The relative excess mortality of unemployed men in Finland cannot fully be explained by demographic, social, and health variables preceding unemployment. Unemployment therefore seems to have an independent causal effect on male mortality. Further studies are needed to elucidate the mechanisms between unemployment and mortality.     

The genetic liability to disability retirement: a 30-year follow-up study of 24,000 Finnish twins

Background

No previous studies on the effect of genetic factors on the liability to disability retirement have been carried out. The main aim of this study was to investigate the contribution of genetic factors on disability retirement due to the most common medical causes, including depressive disorders.

Methods

The study sample consisted of 24 043 participants (49.7% women) consisting of 11 186 complete same-sex twin pairs including 3519 monozygotic (MZ) and 7667dizygotic (DZ) pairs. Information on retirement events during 1.1.1975–31.12.2004, including disability pensions (DPs) with diagnoses, was obtained from the Finnish nationwide official pension registers. Correlations in liability for MZ and DZ twins and discrete time correlated frailty model were used to investigate the genetic liability to age at disability retirement.

Results

The 30 year cumulative incidence of disability retirement was 20%. Under the best fitting genetic models, the heritability estimate for DPs due to any medical cause was 0.36 (95% CI 0.32–0.40), due to musculoskeletal disorders 0.37 (0.30–0.43), cardiovascular diseases 0.48 (0.39–0.57), mental disorders 0.42 (0.35–0.49) and all other reasons 0.24 (0.17–0.31). The effect of genetic factors decreased with increasing age of retirement. For DP due to depressive disorders, 28% of the variance was explained by environmental factors shared by family members (95% CI 21–36) and 58% of the variance by the age interval specific environmental factors (95% CI 44–71).

Conclusions

A moderate genetic contribution to the variation of disability retirement due to any medical cause was found. The genetic effects appeared to be stronger at younger ages of disability retirement suggesting the increasing influence of environmental factors not shared with family members with increasing age. Familial aggregation in DPs due to depressive disorders was best explained by the common environmental factors and genetic factors were not needed to account for the pattern of familial aggregation.     

Trends and dietary determinants of overweight and obesity in a multiethnic population

Objectives : To describe trends in BMI among different ethnic groups in Hawaii and to explore the relation of nutrient and food intake with excess weight. Research Methods and Procedures : We pooled demographic, anthropometric, and nutritional data derived from a detailed diet history for 159, 683 participants of 18 population‐based epidemiological studies conducted in Hawaii over a 25‐year period. The age‐adjusted prevalence of excess weight (BMI ≥ 25 kg/m²) was estimated for 5‐year intervals. To explore dietary determinants of excess weight, we computed odds ratios using logistic regression. Results : During the study period, the prevalence of excess weight increased considerably among all ethnic groups. Native Hawaiians had the highest and Asian Americans had the lowest prevalence of excess weight at all times. Although the percentage of calories consumed from carbohydrates increased, the percentage of calories from fat decreased over time. On an individual level, fat and protein consumption predicted a higher BMI, and dietary fiber intake predicted a lower BMI. Similarly, a higher consumption of meat, poultry, and fish was related to excess weight, whereas fruit and vegetable intake were inversely associated with excess weight. After stratification by ethnicity, the associations were not materially altered among women, but carbohydrates seemed to have a stronger association with excess weight among Native Hawaiian and Japanese men than among white men. Discussion : In this large ethnically diverse population, plant‐based foods and dietary fiber emerged as a potential protective factor against excess weight regardless of ethnicity.     

Risk of early death in extremely overweight young men.

The effect of pronounced obesity in youth on later mortality was studied in 1239 men with extreme overweight, defined as a weight/height 2 greater than or equal to 31 kg/m2, in the population of 331 919 men liable for military service in the Copenhagen area during the period 1943-1977. A random sample of 2948 drawn from the remaining study population served as a control group. All men were followed up until November 1980, by which time 33 deaths had occurred among the extremely overweight subjects compared with 89 in the control group. This gave a mortality ratio (observed to expected number of deaths) of 1.14 (95% confidence limit 0.91-1.40) for controls with a significantly greater mortality of 1.73 (95% confidence limit 1.20-2.41) for obese subjects. The relative risk, estimated from the survival time distributions, was fairly constant around 1.6 throughout the 37 years of observation. Taking into account age at and year of entry in a regression analysis did not change the relative mortality risk. The proportion of natural death was significantly higher in the obese group than in the control group until the age of 30 but not thereafter. Pronounced obesity in youth is a health hazard, manifesting itself particularly in a distinct increase in mortality from natural causes in early adulthood.     

Mitochondrial DNA polymorphisms associated with longevity in a Finnish population

Sequence variation in mitochondrial DNA (mtDNA) may cause slight differences both in the functioning of the respiratory chain and in free radical production, and an association between certain mtDNA haplogroups and longevity has been suggested. In order to determine further the role of mtDNA in longevity, we studied the frequencies of mtDNA haplogroups and haplogroup clusters among elderly subjects and controls in a Finnish population. Samples were obtained from 225 persons aged 90-91 years (Vitality 90+) and from 400 middle-aged controls and 257 infants. MtDNA haplogroups were determined by restriction fragment length polymorphism. The haplogroup frequencies of the Vitality 90+ group differed from both those of the middle-aged controls ( P=0.01) and the infants ( P=0.00005), haplogroup H being less frequent than among the middle-aged subjects ( P=0.001) and infants ( P=0.00001), whereas haplogroups U and J were more frequent. Haplogroup clusters also differed between Vitality 90+ and both the middle-aged subjects ( P=0.002) and infants ( P=0.00001), the frequency of haplogroup cluster HV being lower in the former and that of UK and WIX being higher. These data suggest an association between certain mtDNA haplogroups or haplogroup clusters and longevity. Furthermore, our data appear to favour the presence of advantageous polymorphisms and support a role for mitochondria and mtDNA in the degenerative processes involved in ageing.     

Relation of chronotype to sleep complaints in the general Finnish population

Individuals show variation in their preference for the daily timing of activities. In this study the authors analyzed whether chronotypes associate with sleep duration and sleep-related complaints. The authors used the National FINRISK Study 2007 Survey data on 3696 women and 3162 men, representative of the Finnish population aged 25 yrs and older, for the assessment of chronotype and self-reported sleep. Evening types experienced insomnia symptoms, had nightmares, and had used recently hypnotics significantly more often than other chronotypes among both men and women. In a multinominal logistic regression model predicting insufficient sleep, the association of eveningness with insufficient sleep was not abolished after adjustment for sex, age, and sleep duration. The prevalence of short sleepers was significantly higher in evening types among men than among women, whereas that of long sleepers was significantly higher in evening types among both men and women, as compared with the other chronotypes. These results indicate that eveningness predisposes individuals to a range of sleep complaints.     

A simplified Finnish diabetes risk score to predict type 2 diabetes risk and disease evolution in a German population.

AIMS: The FINDRISC questionnaire is a screening tool to estimate the risks for type 2 diabetes as well as asymptomatic type 2 diabetes. We aimed to evaluate its performance to predict diabetes in a German population and to compare its predictive and detective ability in the same population. METHODS: A total of 552 subjects with increased risk of type 2 diabetes were investigated. All individuals completed the FINDRISC questionnaires and underwent an oral glucose tolerance test (OGTT). All individuals were followed for 3 years and underwent an OGTT again. The performance of the opportunistic screening was assessed with the area under the receiver operating characteristics curve (AUC). An intervention program was carried out for all diabetic and IFG/IGT patients at baseline. RESULTS: For identification, the asymptomatic type 2 DM was named Condition 1; prediction of type 2 DM risk in the follow-up survey as Condition 2; and diabetes risk predicting in a hypothetical case of survey without intervention program as Condition 3. The ROC-AUC in the three condition were AUC (FINDRISC1)=0.745, AUC (FINDRISC2)=0.789, and AUC (FINDRISC3)=0.775, respectively. A significant association between FINDRISC and evolution of disease was found, but the variation of plasma glucose during the three years follow-up was not associated with FINDRISC. People in the intervention group with an improvement of glucose tolerance had a smaller FINDRISC score than persons with an unchanged or progressive condition of disease. CONCLUSION: FINDRISC was validated in our study as a simple tool with high performance to predict diabetes risk and less efficient to identify asymptomatic type 2 diabetes. People with lower FINDRISC score will benefit easier from preventive intervention.     

Quantitation of serum angiopoietin-like proteins 3 and 4 in a Finnish population sample

We have developed and validated quantitative ELISAs for human angiopoietin-like (ANGPTL)3 and 4 and correlated their serum levels with parameters of lipid and carbohydrate metabolism. For this study, we used a random subsample of the Health 2000 Health Examination Survey consisting of 125 men and 125 women, aged 30–94 years. The anthropometric and biochemical parameters of subjects were characterized in detail. ANGPTL 3 and 4 levels were determined using the developed ELISAs. The intra- and inter-assay coefficients of variation for the assays were less than 15%. The average serum concentration of ANGPTL3 was 368 ± 168 ng/ml (mean ± SD) and for ANGPTL4 it was 18 ± 23 ng/ml (mean ± SD). ANGPTL4 serum levels displayed high variability between individuals ranging from 2 to 158 ng/ml. In post-heparin plasma, both ANGPTL 3 and 4 were increased. Low levels of ANGPTL3 were associated with decreased HDL-cholesterol and increased triglyceride levels. ANGPTL4 levels were positively correlated with FFAs (P = 0.044) and waist-hip ratio (P = 0.016). The developed ELISAs will be important tools to clarify the role of ANGPTL 3 and 4 in human energy metabolism and partitioning of triglycerides between sites of storage (adipose tissue) and oxidation (skeletal and cardiac muscle).     

Prevalence and associated factors of overweight and obesity in a Chinese rural population

Background: Overweight and obesity are now considered as a serious health problem, and a very important risk factor for many diseases. Objective: This study was designed to investigate the epidemiologic features of overweight and obesity among rural adults in China. Method and Procedures: A cross‐sectional survey was conducted during 2004–2005, using a multistage cluster sampling method to select a representative sample in Fuxin county, Liaoning province, China. A total of 29,970 adults, aged ≥35 years, were examined. At baseline, lifestyle and other factors were obtained. Overweight and obesity were defined according to the classification by the World Health Organization. Results: Overall, the prevalence of overweight was 18.6%; 15.1% in men and 22.1% in women. The prevalence of obesity was 1.7%; 1.2% in men and 2.2% in women. Multivariable logistic regression revealed certain risk factors of obesity that included being a women, Mongolian nationality and education status of over junior high school level. Moderate physical activity alone was shown as protective factor. Discussion: Although the prevalence of obesity was low, overweight was relatively high in the Chinese rural population, especially in adult women. Gender, diet, physical activity, education levels, and ethnicity were associated with the prevalence of these health conditions.     

Nest mortality in a population of small mammals

Female white-footed micePeromyscus leucopus (Rafinesque, 1818) and their dependent offspring were monitored in nest boxes to determine the extent and causes of nest mortality. The mortality of dependent young was high (561 of 838; 66%) and variable among years. Most mortality involved the loss of entire litters (112 of 183 litters; 61%), with half of these losses attributed to the death of lactating females before the young were weaned (59 of 112 litters; 53%). Most mortality was from unknown causes, although infanticide, energetic constraints and predation were identified in a small number of cases. Predation is likely the major source of mortality in this population.