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L Belmont

Publications and source records attributed to L Belmont.

At least 19 recordsLinked to original sources
PubMed1990

Genetic and molecular analysis of the SOE1 gene: a tRNA(3Glu) missense suppressor of yeast cdc8 mutations.

The CDC8 gene of Saccharomyces cerevisiae encodes deoxythymidylate (dTMP) kinase and is required for nuclear and mitochondrial DNA replication in both the mitotic and meiotic cell cycles. All cdc8 temperature-sensitive mutants are partially defective in meiotic and mitochondrial functions at the permissive temperature. In a study of revertants of temperature-sensitive cdc8 mutants, the SOE201 and SOE1 mutants were isolated. The SOE201 mutant is a disome of chromosome X to which the cdc8 gene maps. Using the chromosome X aneuploids to vary cdc8 gene dosage, we demonstrate that different levels of dTMP kinase activity are required for mitotic, meiotic or mitochondrial DNA replication. The SOE1 mutant contains a dominant suppressor that suppresses five different cdc8 alleles but does not suppress a complete cdc8 deletion. The SOE1 gene is located less than 1.5 cM from the CYH2 gene on chromosome VII and is adjacent to the TSM437-CYH2 region, with the gene order being SOE1-TSM437-CYH2. SOE1 is an inefficient suppressor that can neither suppress the cdc8 hypomorphic phenotype nor restore dTMP kinase activity in vitro. SOE1 is a single C to T mutation in the anticodon of a tRNA(3Glu) gene and thereby, produces a missense suppressor tRNA capable of recognizing AAA lysine codons. We propose that the resultant lysine to glutamate change stabilizes thermo-labile dTMP kinase molecules in the cell.

Alleles↗
PubMed1987

Mild mental retardation and severe mental retardation compared: experiences in eight less developed countries.

Frequencies of Severe Mental Retardation (SMR) and Mild Mental Retardation (MMR) were obtained from pilot surveys of severe childhood disability in 8 less developed countries. Approximately 1,000 children aged 3 to 9 years were surveyed in each location. The surveys used a Ten Question (TQ) door-to-door interview, usually of the mother, as a screening procedure and a systematic medical and psychological assessment for the diagnosis. Diagnostic categories of SMR (IQ less than or equal to 55) and MMR (IQ greater than 55, less than or equal to 70) were assigned by well trained local psychologists, using formal and informal techniques of assessment. Contrasting frequencies and distributions for MMR compared with SMR are shown for each location. No consistent pattern for MMR versus SMR emerged, neither regarding frequency, male/female ratio, average age nor socio-economic status of household. By contrast, MMR did differ from SMR consistently regarding consanguinity of parents, the presence of associated impairments and the positive report of symptoms at interview. Also, the families of all MR children were lower in SES than comparison families. An interpretation of these findings is offered: the more severely disabled children tend to be assessed as SMR, but so do other children who might, in better circumstances, be assessed as MMR. The relevance of this interpretation is discussed, in terms of assessment and of rehabilitation, and as a guide to further epidemiologic studies.

Asia, Southeastern↗
PubMed1986

"Serious" mental retardation in developing countries: an epidemiologic approach.

In this paper we first present methods and preliminary results of pilot surveys of "serious" mental retardation (IQ less than or equal to 55); the surveys included screening and diagnostic components and were carried out in the less-developed world. Next we discuss two problems raised by these surveys: one is the diagnosis of a case and its clinical dimensions, and the other is the interpretation of prevalence. In the next section we illustrate epidemiological approaches to the analysis of such data, in particular their relevance to prevention. Lastly, we propose that the two-stage survey approach developed in the course of the pilot work can provide a valuable basis for planning and prevention, if certain key conditions can be met.

Bangladesh↗
PubMed1979

Obesity in nineteen-year-old men: family size and birth order associations.

The authors analyzed the prevalence of obesity by family size and birth order for a total population of over 280,000 19-year-old Dutch males, who were born between 1944 and 1947 and who were from one- to five-child families. Obesity was defined by a relative weight index, 120% or more of the standard of weight for height. Overall obesity prevalence was 1.83%; sons of manual workers were more prone to obesity than sons of non-manual workers. Individuals from one-child families (only children) were uniquely at risk for obesity, particularly in the non-manual social class. This result was similar to reported findings for childhood obesity.

Adult↗
PubMed1978

Child spacing and birth order: effect on intellectual ability in two-child families.

The effect on intellectual ability of the spacing of the birth of siblings was studied in two series of young men from two-child families: (i) 535 pairs of brothers and (ii) 1511 unrelated firstborn and secondborn. Birth-order effect and level of ability were not influenced by length of interval between firstborn and secondborn.

Birth Order↗
PubMed1978

Maternal age and children's ability.

Associations of maternal age at birth and subsequent intelligence test scores of children were examined in a series of over 1500 young men from the Netherlands. All subjects were members of 2-child families and were resident in Amsterdam at age 19 yr. Possible confounding by birth order, spacing interval, social class and sex of sibling were considered. Significant correlations between maternal age and child's ability remained in three of the four possible birth order/social class combinations.

Adult↗
PubMed1977

Relation of birth order, family size and social class to psychological functions.

Findings are reported on birth-order and family-size effects for five psychological functions measured by the military preinduction test battery which was administered to a total population of 19-yr.-old Dutch men. These men were born between 1944 and 1946, were members of 1- to 6-child families and were from the two major social classes. A clear birth-order gradient was present on all test measures for both social classes. Family-size effects, however, differed by social class. The results extend to a range of psychological functions the findings previously reported for a single test of non-verbal intelligence, suggesting that family-structure variables play a role in understanding intellectual development.

Adult↗
PubMed1976

Birth order, family size and school failure.

The effect of birth order on educational outcome in the Netherlands is reported for two major social classes, manual and non-manual. The rates of school failure (those who attended schools for the mentally retarded and who failed lower school) were studied in a population of some 200,000 young adult Dutch males born between 1944 and 1946 and whose families of origin had from one to six children. The data used were the records of the Dutch military pre-induction examination. Rates of school failure rose both with increased birth order and with increased family-size, with the exception of one-child families. School failure rates for the first, middle-and last-born were examined for the two social classes, with family size controlled. In general, school-failure rates were significantly related to birth-order position. For each family size and in both social classes, the last-born were at greater risk of school failure than were the first-born.

Adult↗
PubMed1973

Birth order, family size, and intelligence.

The relation of birth order and family size to intellectual performance, as measured by the Raven Progressive Matrices, was examined among nearly all of 400,000 19-year-old males born in the Netherlands in 1944 through 1947. It was found that birth order and family size had independent effects on intellectual performance. Effects of family size were not present in all social classes, but effects of birth order were consistent across social class.

Adult↗