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Biomedical subjects

O Stark

Publications and source records attributed to O Stark.

At least 19 recordsLinked to original sources
PubMed1989

Weight and age at menarche.

In the National Child Development Study (1958 cohort) information on their age at menarche and their weights and heights measured at 7, 11, and 16 years was available for 4427 girls. The distribution of age at menarche was not influenced by social class. Weight adjusted for height did not play an important part in the timing of sexual maturation of the girls in the study. Relative weight (weight expressed as a percentage of standard weight) at the ages of 7 and 11 years explained only 3.2%, and 4.9%, respectively of the variation in age at menarche, and changes in relative weight between these two ages accounted for 2%. Girls with early menarche were more likely to be overweight at ages 7, 11, and 16 years than those with late menarche, although early menarche was also reported by girls who were underweight or of average weight. These findings support the hypothesis that in well nourished populations the relation between menarche and body size is largely regulated by genetic factors and that nutrition is less important.

Adolescent↗
PubMed1989

Relative deprivation and international migration.

This article provides theoretical reasoning and empirical evidence that international migration decisions are influenced by relative as well as absolute income considerations. Potential gains in absolute income through migration are likely to play an important role in households' migration decisions, but international migration by household members who hold promise for success as labor migrants can also be an effective strategy to improve a household's income position relative to others in the household's reference group. The findings reported in this article provide empirical support for the hypothesis that relative deprivation plays a significant role in Mexico-to-U.S. migration decisions. The findings also suggest that this migration is an effective mechanism for achieving income gains in households that send migrants to the U.S. and that households wisely choose as migrants those of their members who are most likely to provide net income gains.

Adolescent↗
PubMed1987

In vitro and in vivo behaviour of rat islets of Langerhans treated with MHC antisera and complement.

The in vitro and in vivo behaviour of rat islets of Langerhans pretreated with polyclonal MHC antisera and complement was investigated. Complement-dependent cytotoxicity against rat islets was mediated by the antisera which were either directed against all MHC products ("a anti-u") or against products of the B-region of rat MHC ("Ba anti-Bu"). There were only minor alterations in glucose-stimulated insulin secretion and in 3H-leucine incorporation into islet proteins and into (pro)insulin in the pretreated islets. The syngeneic transplantation of "Ba anti-Bu"-treated islets led to a permanent graft survival in all streptozotocin-diabetic rats but after "a anti-u"-pretreatment permanent graft survival was only achieved in 33% of the syngeneic recipients. It is concluded, that in the latter case a complement-dependent cytotoxicity is exerted against the islets which may not allow sufficient in vivo survival. Now it appears necessary to look for effects of pretreatment prior to an allogeneic transplantation.

Animals↗
PubMed1987

Genetic studies of IDDM in BB rats: the incidence of diabetes in F2 and first backcross hybrids allows rejection of the recessive hypothesis.

The BB rat spontaneously develops an IDDM with many analogies to human IDDM, i.e. the genetic basis is a puzzle, since more than one mode of inheritance of IDDM in BB rats has been proposed. These different proposals reflect the heterogeneity of BB rats used for genetic studies. This prompted us to investigate the inheritance of IDDM in two subpopulations of BB rats (BB/OK and BB/PhiK) by crossing studies with the production of (diabetic BB x LEW 1.A) F1, F2 generations and of first backcross hybrids onto BB (B1BB) and LEW.1A (B1A) rats respectively. Both BB rat subpopulations were different in origin, degree of inbreeding, incidence and age at onset of diabetes and in certain immunologic, metabolic and hematologic traits. All hybrids were serotyped and checked for diabetes by determination of urine and plasma glucose twice weekly up to an age of 200 days. None of the F1 and B1A hybrids developed diabetes. Some cases were observed in the F2 hybrids with a different incidence in the two subpopulations (2.3% in BB/OK, 11.0% in BB/PhiK). The percentage of diabetes in the B1BB hybrids was 13.8% (BB/OK) and 24.0% (BB/PhiK) respectively. All diabetic hybrids were characterized by at least one RT1uv haplotype which was derived from the original BB animals. These results demonstrated clearly (1) that the mode of inheritance depends on the genotype of the animals observed and (2) simple autosomal-recessive genetics cannot be accepted for BB rat diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Congenital cytomegalovirus infection: a cause of sensorineural hearing loss.

Prospective studies have suggested that about 108 children with congenital cytomegalovirus (CMV) infection and bilateral sensorineural hearing loss are born each year in England and Wales; this represents about 12% of all children with congenital sensorineural hearing loss. Over a nine year period 1644 children aged between 6 months and 4 years who were attending the Nuffield Hearing and Speech Centre were screened for CMV infection. The prevalence of CMV in the urine of children with sensorineural hearing loss but no immediate family history of deafness was nearly twice that (13%) found in other children with impaired hearing and those with normal hearing (7%). These findings indicate the importance of CMV as a cause of hearing loss.

Child, Preschool↗
PubMed1987

Genetic heterogeneity in different BB rat subpopulations.

Two different BB-rat subpopulations were followed over 7 inbred generations under identical environmental conditions: BB/OK as derived in 1983 from the original stock in Ottawa, BB/PhiK as derived in 1983 from a stock at the University of Pennsylvania, Philadelphia. They showed significant differences in incidence, age at onset, untreated survival time of diabetes, leucopenia and body weight gain. By crossing experiments these phenotypical differences could be attributed to a genetic diversity between the 2 subpopulations. It is concluded that this genetic diversity is based on the heterogeneity of the parental BB Wistar rat stock and that the genetic differentiation between subpopulations of a different history is favoured by the "bottle neck effect", selection, mutation and genetic drift. The study of defined subpopulations and of their genetic interaction will provide deeper insight into the mechanisms of inheritance of diabetes in different species.

Animals↗
PubMed1986

Antibody response to sheep red blood cells in four substrains of BB rats, some other strains and interstrain F2 hybrids.

Primary and secondary antibody responses to SRBC were assayed in three substrains of dp BB rats, one strain of ndp BB rats, in their parental WOK rats, in highly inbred LEW rats, in two RT1 congenic strains LEW.1A and LEW.1W, and in the recombinant LEW.1WR2 strain. Furthermore, interstrain F1 and F2 hybrids of two dp BB substrains with congenic animals were tested. A significant lowering of the primary antibody response was found in two dp BB substrains and in the recombinant LEW.1WR2 strain. A transient lowering was shown in ndp BB rats. The third dp BB substrain responded well. The observed differences among three dp BB substrains only indicate that the level of antibody response to SRBC cannot be taken as a further marker, besides the RT1uv haplotype, for spontaneous development of the IDDM in BB rats. The observed decrease in the primary antibody response in the RT1 recombinant LEW.1WR2 rats and in one group of interstrain F2 hybrids typing as homozygous RT1uv may have another meaning. They could indicate some immunoregulatory effects of the RT1 haplotype on the supposedly multigenic response to SRBC in rats. No significant differences were found in the secondary antibody responses to SRBC.

Animals↗
PubMed1986

Obesity in 16-year-olds assessed by relative weight and doctors' rating.

Weights and heights at age 16 of 5652 boys and 5280 girls from the National Child Development Study (NCDS) were measured. At this examination, school medical officers rated the boys and girls into one of the following categories: grossly obese, moderately obese, normal, thin or very thin. A comparison is made between doctors' rating and assessment of obesity by relative weight (RW). Obesity was defined as RW greater than 120. Overall 803 (15.2 per cent) girls were rated obese by doctors compared with 469 (8.9 per cent) identified by RW. Only 414 (7.8 per cent) girls were considered obese by both methods. In boys the difference between the two methods was less marked. There were 362 (6.4 per cent) boys rated as obese by doctors, 404 (7.2 per cent) by relative weight and 262 (4.6 per cent) by both methods. The discrepancies demonstrate that one method of assessment cannot replace another. Doctors' rated considerably more girls than boys as obese. Although at this age girls were heavier than boys for a given height, the doctors' rating may also reflect the different attitudes towards obesity in men and women which are prevalent in our society. Without comparison with a more accurate measure of adiposity it is not possible to reach a definite conclusion as to whether clinical assessment, relative weight, or indeed both methods combined are the most suitable for identifying obese adolescents.

Adolescent↗