Can economic stress affect secondary sex ratio in Poland?
The ratio of male to female births described as the male proportion is expected to be about 1.06. The secondary sex ratio can be influenced by various stresses experienced by parents (e.g., parents' exposure to chemical and physical pollution, natural phenomena, wars and economic crises). The seminal study in this field speculated that fewer goods and services than needed or desired might sufficiently stress human populations to lower the secondary sex ratio. The main purpose of this study is to examine the relationship between economic stress and the fluctuations of sex ratio at birth in Poland. The statistical analysis was based on annual demographic data obtained from year-books issued by the Central Statistical Office on the overall number of male and female live births in Poland in the years 1956-2005 as well as on the annual data of percentage change in total private consumption. In order to verify the hypothesis that the observed time-series of the secondary sex ratio in Poland declines with deterioration in economic conditions, we constructed mathematical models (ARIMA) of both analyzed phenomena following the statistical procedure proposed by Catalano and Bruckner . We found a statistically significant decline of SSR in Poland over the last 50 years. The decrease appeared to be stronger in villages than in towns. However, the consumption rate as related to the strength of economic stress had no effect on the fluctuation of the sex ratio at birth.
The effects of psychological stress, gender and age on hair and skin pigmentation levels were evaluated in the reported study. The material included Polish high-school and university students aged 18-22 (in the age range 17.50-22.49). All subjects who had sunbathed or used tanning beds or lamps, skin tanning agents, tanning extenders and/or medical agents affecting skin pigmentation during the 60 days preceding the beginning of the study were excluded. The use of hormonal contraceptives within a month prior to the study was also an excluding factor. Stress levels were evaluated by the Perceived Stress Scale (PSS-10) in the Polish adaptation, while hair and skin pigmentation levels were assessed with a dermaspectrometer (Cortex Technology®, Denmark, 2007). The study was carried out with the exclusion of the summer period. Skin pigmentation was evaluated in 395 subjects (264 women and 131 men). Hair pigmentation was analyzed in a smaller group of 351 subjects (223 women and 128 men), as some had had their hair dyed within 12 months prior to the study while in some others the hair was too short to be correctly measured.
Regardless of their age, the studied women felt much more stress related to their life situation and were characterized by stronger skin pigmentation than the examined men. No sex differences were identified with regard to hair pigmentation. In the studied period of ontogenesis (18-22 years of age), hair pigmentation levels increased with age, while skin melanization remained stable. Disregarding the effects of age and sex, the level of perceived stress was negatively correlated with skin pigmentation levels; no such relationship was found for hair melanization.
The goal of the study was verification of fat mass and obesity-associated (FTO) gene polymorphisms as significant risk factors of obesity in the population of Polish children. Body mass index (BMI) and DNA were evaluated, where DNA was extracted from saliva, collected from 213 children at the age of 6-13 years. DNA was genotyped by PCR (polymerase chain reaction) and HRM (high resolution melting) techniques, as well as by direct sequencing. Three (3) FTO polymorphisms were identified: rs9939609, rs9926289 and rs76804286, the last polymorphism located between the first two. For the first time, absolute linkage disequilibrium (LD) of FTO gene rs9939609 and rs9926289 polymorphisms was confirmed in data for the Polish population (D’=1, r2=1). The lack of a complete dependence among the three single nucleotide polymorphisms (SNPs) of the FTO gene was a consequence of the concurrence of homozygotes with minor alleles A of rs9939609+rs9926289 of FTO (AA+AA) with major alleles of rs76804286 (GG). A case-control association analysis for BMI in obese children (n=51), as compared to normal-weight children (n=162), was based on the effects of genotypes homozygous for the minor alleles of the studied SNPs in recessive and codominant inheritance models (assuming an independent effect of each genotype). A comparison of children with normal BMI with obese children indicate a strong co-dominant effect of a genotype in homozygotes of minor alleles (AA+AA) of completely linked rs9939609+rs9926289 (OR at age 8.89 ± 1.54 years=4.87, 95% CI 1.81-13.12, p=0.002). An almost five-fold increase of obesity risk in the examined children indicates that the genetic factors, associated with excessive body weight gain, exert stronger effects in the early period of ontogenetic development vs. puberty and adulthood. The role of genetic factors in predisposing to obesity declines with age
The objective of the study was to verify whether or not FTO rs9939609, rs9926289 and TMEM18 rs4854344, rs6548238, rs2867125 variants are important risk factors for overweight and/or obesity in Polish children aged 6-16 (n=283). FTO rs 9939609 and rs9926289 exhibited a strong codominant obesity-predisposing effect of genotypes homozygous for minor alleles (OR=5.42, 95% CI: 2.04-14.39, p=0.0006). The important finding of the study is increased risk of overweight (OR=5.03, 95% CI: 1.15-21.93, p=0.0306) in individuals homozygous for the minor alleles rs4854344, rs6548238 and rs2867125 in the recessive inheritance model, while no other significant associations between TMEM18 variants and risk of obesity were found. Given the identified interaction TMEM18 genotype × BMI category (p=0.0077), it seems that the effect of homozygous for the minor alleles may be compared to a “weight guard”, which significantly increases the risk of overweight, but not of obesity, because it promotes weight gain only up to the threshold of obesity. Conclusion: The proposed hypothetical effect (“weight guard”) of homozygous for the minor alleles in the TMEM18 based on a rather small sample is a possible explanation of the effects of minor alleles, which minimize the risk of obesity.