Biomedical subjects

S Koziel

Publications and source records attributed to S Koziel.

5 recordsLinked to original sources

PubMed2002

Effect of low versus normal birthweight on menarche in 14-year-old Polish girls.

OBJECTIVE: The relationship between intrauterine growth retardation and sexual maturation has not been completely established. The aim of the present study was to compare menarche in 14-year-old Polish girls of low and normal birthweight, along with an evaluation of the impact of socio-economic status and body mass index (BMI). METHODS: We studied 1060 girls (177 pre- and 883 post-menarche) aged 13.5-14.5 years. These girls attended the 7th grade of randomly selected primary schools in Wroclaw, Poland. The BMI was used as a measurement of general adiposity. The cut-off value of the 10th percentile of birthweight for gestational age was used to differentiate between girls born small for gestational age (SGA) and girls with a birthweight appropriate to gestational age (AGA). Parental education level and other measures were used to assess socio-economic status (SES). RESULTS: Birthweight (OR = 2.54; 95% CI 1.22-5.28) and BMI at the age of 14 years (OR = 7.93; 95%CI 4.67-13.48) were factors affecting the onset of menarche among the 14-year-old girls. CONCLUSION: Polish girls born small for gestational age are more likely to have experienced menarche by the age of 14 years, compared with their peers of normal weight at birth. These findings seem to be consistent with the hypothesis that the age of menarche is, to some extent, set by patterns of gonadotropin release, established prior to birth. Additionally, the age of menarche varies depending on levels of fat accumulation during childhood and adolescence.

Adolescent↗

PubMed2001

Waiting for Trivers and Willard: do the rich really favor sons?

Parental investment theory has been put forward as a major evolutionary argument explaining male or female biased birth sex ratio, the Trivers-Willard (T-W) hypothesis, predicting that parents living in good circumstances will bias their investment to sons, whereas parents in poor circumstances will bias their investment toward daughters. Tests of the T-W hypothesis on human beings have shown limited evidence for parents appearing to differentiate their investment to sons or daughters according to the reproductive potential of each sex. The present study tests the T-W hypothesis among a large contemporary Polish sample using first birth interval and extent of breastfeeding as measures of parental investment, and economic status and level of parental education as measures of parental condition. The extents to which parental investment and markers of parental condition vary by sex of the child were examined using log-linear analysis. Weak support for the T-W effect is found among families where fathers were best educated, where a greater proportion of first-born boys are breastfed longer than girls, while the opposite trend is observed among families with fathers with lowest levels of education. Although the present study does not fully support the T-W hypothesis, it gives evidence of greater investment in female offspring at the lower extremes of income, and greater investment in males at higher levels of income.

Adult↗

PubMed2001

Birth order and BMI in teenage girls.

The goal of this study was to investigate the relation of birth order to relative weight and prevalence of obesity in a group of 13-15 years old girls. In 1997, 1458 girls were examined. The height and weight measured by trained staff were recorded. Family size and birth order were obtained by a questionnaire. For the purpose of the present study, 776 and 250 girls coming from two- and three-child full families, respectively, were selected from the total sample on the basis of complete information. The Body Mass Index (kg/m2) was adjusted to reference US population (NCHS) by means of the LMS parameters. Prevalence of overweight and obesity was defined according to recommendation of the International Obesity Task Force. The effect of birth order on BMI was tested by one-way analysis of variance. Prevalence of obesity was tested by the means of Pearson chi-square. First and second born girls from two-sibling families did not show significant differences in average standardized BMI. Relative weight significantly differs among girls coming from three sibling families, decreasing along with the birth order. The first-born girls were 1.5 times at higher risk of obesity in comparison to later-born girls. Differences in the proportion of overweight girls among birth order groups showed a high significance within three sibling families.

Adolescent↗

PubMed2000

Parental education, body mass index and prevalence of obesity among 14-year-old boys between 1987 and 1997 in Wrocław, Poland.

The main aim of this study was to examine changes in relative weight and prevalence of obesity across a ten-year period among 14-year-old boys according to parental education level. Data from two surveys, carried out in 1987 and 1997, of boys attending the 7th grade of primary schools in Wrocław were used in the analysis. The heights and weights of 3165 boys aged 14 years selected from cohort of 6969 7th and 8th grade boys from all primary schools of the city Wrocław were used. The data of the second sample of 14-year-old boys (n = 1014) were obtained from a health examination study carried out in the Silesian Centre for Preventive Medicine, 'DOLMED', in Wrocław in 1997. All boys attended the 7th grade of 34 randomly selected primary schools from a total of 129 schools in the city of Wrocław. Social status was assessed on the basis of parental education level scored to four categories: university, secondary school, trade school, and elementary school. The prevalence of overweight and obesity was defined as the percentage of children above the 85th and 95th percentiles of the body mass index (BMI), the means of which were 21.27 and 23.75 kg/m2 respectively. Prevalence of overweight among boys is slightly lower in the 1997 sample, whereas the prevalence of obesity shows the opposite trend and is higher by more than one percent in comparison with the 1987 sample. Similar trends of declining medians and increasing variance are observed in all educational groups. The differences in medians between the two samples within educational groups did not achieve statistical significance for the groups with parents with education at elementary level and fathers with university education. There is a trend toward increasing prevalence of obesity across the decade considered, according to father's education level. With respect to mother's education levels, the most dramatic changes in BMI and obesity occurred in the elementary education group, where the percentage of obese subjects increased more than twofold. A significant increase is also observed in the group with parents attaining university education.

Adolescent↗

PubMed1999

Evolutionary algorithms, homomorphous mappings, and constrained parameter optimization.

During the last five years, several methods have been proposed for handling nonlinear constraints using evolutionary algorithms (EAs) for numerical optimization problems. Recent survey papers classify these methods into four categories: preservation of feasibility, penalty functions, searching for feasibility, and other hybrids. In this paper we investigate a new approach for solving constrained numerical optimization problems which incorporates a homomorphous mapping between n-dimensional cube and a feasible search space. This approach constitutes an example of the fifth decoder-based category of constraint handling techniques. We demonstrate the power of this new approach on several test cases and discuss its further potential.

Algorithms↗