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Biomedical subjects

K W Dumars

Publications and source records attributed to K W Dumars.

12 recordsLinked to original sources
PubMed1989

A single base mutation that converts glycine 907 of the alpha 2(I) chain of type I procollagen to aspartate in a lethal variant of osteogenesis imperfecta. The single amino acid substitution near the carboxyl terminus destabilizes the whole triple helix.

Type I procollagen was examined in cultured skin fibroblasts from a patient with a lethal variant of osteogenesis imperfecta. About half of the pro-alpha chains were post-translationally overmodified and had a decreased thermal stability. The vertebrate collagenase A fragment had a normal thermal stability, but the B fragment had a decreased thermal stability. Therefore, there was a change in primary structure in amino acids 776-1014 of either the alpha 1(I) or alpha 2(I) chain. Three of five cDNA clones for the alpha 2(I) chain contained a single-base substitution of an A for a G that converted the codon for glycine at amino acid position 907 to aspartate. Complete nucleotide sequencing of bases coding for amino acids 776 to 1014 of the alpha 2(I) chain was carried out in one cDNA clone that contained the mutation in the glycine codon and in one that did not. Also, nucleotide sequencing was performed of bases coding for amino acids 776-1014 of the alpha 1(I) chain in seven independent cDNA clones. No other mutations were found. Therefore, the single base substitution that converts glycine 907 in the alpha 2(I) chain to aspartate is solely responsible for the decreased thermal stability of the type I procollagen synthesized by the proband's fibroblasts. Also, glycine 907 of the alpha 2(I) chain is an important component of a cooperative block that determines the melting temperature of the whole molecule.

Amino Acid Sequence↗
PubMed1987

Prevention of developmental disabilities: a model for organizing clinical activities.

Prevention of developmental disabilities receives widespread support, however, a comprehensive approach involving federal and local governments, major professional groups, and the general public has yet to be defined and implemented. Three major issues appear to impede a coordinated approach: (a) prevention's image problem; (b) the complexity surrounding prevention efforts; and (c) the absence of consistent evaluation methods. The University of California, Irvine-University Affiliated Program has developed a model for prevention activities in response to these issues. This model is interdisciplinary, promotes reasoned cooperative efforts, and provides a basis for evaluation and research. This paradigm can be helpful to policy makers in prioritizing prevention activities. The model is composed of five major and functional approaches to prevention with a central core devoted to ethical considerations. The model emphasizes the variety, scope and interdisciplinary nature of prevention/intervention activities, as well as the necessity for a longitudinal approach.

Attitude↗
PubMed1985

Screening for developmental disabilities.

Developmental disabilities are responsible for a combination of severe physical, mental, psychological and social deficits. They develop before age 22 years and involve a little more than 1% of the population. Screening for developmental disabilities is the first step in their prevention. Various screening instruments are available for use throughout the developmental years that are designed to detect the wide variety of developmental problems that interfere with a developing person's optimal adaptation to his or her environment. The screening instruments must be inexpensive, reproducible, widely available and cost effective to the child, family and society.

Adult↗
PubMed1977

Minimizing the risk of amniocentesis for prenatal diagnosis.

Although the risk of amniocentesis in the second trimester of pregnancy is small, untoward sequelae can be further reduced. One hundred twenty amniocenteses were attempted during a two-year period. In eight instances, the patient had to return for a second tap because of bacterial contamination, inadequate number of fetal cells, or inability to obtain amniotic fluid. These eight patients all underwent repated amniocentesis and successful karyotyping. There were no major complications and one minor complication. Two spontaneous abortions were not apparently related to the procedure. In both these cases, fluid could not be obtained because one patient had a blighted ovum with a small sac and the other had large uterine fibromyomas.

Adult↗
PubMed1976

Prenatal diagnosis and genetic counseling.

Since the early 1960's knowledge regarding human genetics has increased at an exponential rate. Because genetics was not commonly taught in medical schools before the late 1960's, this review article is intended to acquaint physicians or refresh their knowledge regarding chromosomal, mendelian and multifactorial inheritance and the indications for prenatal diagnosis. Establishing an accurate diagnosis and mode of inheritance is essential in identifying and selecting those families at risk for genetic disease in their offspring. Medical genetics is evolving as a specialty in order to provide consultation and, if needed, management of those families who would benefit by genetic services. Families who would benefit from genetic counseling include, for example, those in whom any of the following conditions is present: known chromosomal disorders, known disorders due to mendelian inheritance, mental retardation of unknown origin, failure of sexual maturation or failure of sexual development, congenital malformations, floppy infant syndrome or leukemia.A list of more than 70 disorders now detectable in a fetus by means of amniocentesis provides a beginning in the prevention of genetic disease. Knowledge regarding these diseases allows a physician to provide families with accurate risk figures so that they may make informed decisions about having children. Also, a compassionate and nonjudgmental approach to counseling is essential. Decisions, in the final analysis, must be made by the family but aided and supported by the physician.

Chromosome Aberrations↗
PubMed1976

E trisomy phenotype associated with small metacentric chromosome and a familial Y-22 translocation.

As a result of this case report, several entities are postulated due to an extra metacentric D or E chromosome: 1) infants presenting with a phenotype similar to the E 18 trisomy; however, the karyotype can be interpreted as either a deleted E or D chromosome; 2) another group of children all presenting with mental retardation, facial asymmetry, scoliosis and cerebral palsy, postulated due to a partial trisomy of E 16 or E 17; 3) individuals with a normal phenotype, but chromosomally presented with an additional satellited metacentric chromosome consistent with centric fusion of a D or G chromosome and 4) children presenting with an inconsistent phenotype and chromosomally presenting with an extra chromosome manifesting satellites or satellite association; the same chromosome abnormality often is found in unaffected parents and/or sibs.

Chromosome Aberrations↗
PubMed1975

X-autosome translocation with a 47,XXXY qs,t(9p-;Xq+) karyotype.

A male with a karyotype 47,XXXY qs,t(9p-;Xq+) was ascertained utilizing ASG-banding. The karyotype was repeated because the original diagnosis of Klinefelter syndrome (47,XXY) was inconsistent with many of the stigmata present. It is suggested that many karyotypes completed prior to the advent of banding techniques will be repeated in an attempt to provide more accurate diagnosis, describe more aberrations, and possibly establish new syndromes.

Child↗