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Biomedical subjects

J L Simpson

Publications and source records attributed to J L Simpson.

At least 19 recordsLinked to original sources
PubMed1979

Localization of the nucleolar organizer by computer-aided analysis of a variant no. 21 in a human isolate.

A variant chromosome no. 21 consisting of two stalks and two satellites in tandem was detected during a survey of a human isolate. The variant segregated in three generations of a large kindred. One male had the variant no. 21, a metacentric Y, and a 47,XXY complement; however, no other evidence of chromosomal nondisjunction was found. Computer-aided analysis of sequentially stained variant no. 21 chromosomes indicated that silver-stained material corresponded to the proximal stalk region (as defined by Giemsa), but often covered both the distal stalk and satellite (also as defined by Giemsa). These data support the hypothesis that human nucleolar organizers are localized to the stalks of acrocentric chromosomes.

Azure Stains↗
PubMed1979

Analysis for amniotic fluid crystallization in second-trimester amniocentesis.

A potential complication of second-trimester amniocentesis for genetic indications is inadvertent needle insertion into the maternal bladder, resulting in aspiration of urine rather than amniotic fluid. Amniotic fluid forms a characteristic crystalline arborization pattern when allowed to air dry. We utilized this property of amniotic fluid to distinguish amniotic fluid from maternal urine. In 24 of 25 cases studied in a randomized blind fashion the crystalline arborization test correctly identified amniotic fluid, whereas none of the 25 urine samples showed this pattern. Our study indicates that the crystalline arborization test is reliable in distinguishing amniotic fluid from maternal urine during the second trimester of pregnancy.

Amniocentesis↗
PubMed1978

Male pseudohermaphroditism: genetics and clinical delineation.

The genetics and clinical delineation of male pseudohermaphroditism are reviewed. These disorders are categorized initially by their genetic etiology--cytogenetic, Mendelian, or teratogenic. It is especially important to distinguish cytogenetic forms, usually associated with 45,X/46,XY mosaicism, from Mendelian (genetic) forms because in the former the prevalence of gonadoblastomas or dysgerminomas is about 15--20%. Genetic forms include (1) those associated with a multiple malformation pattern, (2) those due to an error in adrenal or testicular hormonal biosynthesis, (3) complete testicular feminization, (4) incomplete testicular feminization, (5) Reifenstein syndrome, (6) pseudovaginal perineoscrotal hypospadias, and (7) agondia, and possibly other conditions. Incomplete testicular feminization and the Reifenstein syndrome may or may not represent varied expressivity of the same trait. The designation pseudovaginal perineoscrotal hypospadias is appropriate only if constellations of clinical features are present and if no metabolic abnormalities are demonstrable. Etiology and available genetic data are reviewed for each of these disorders.

Abnormalities, Multiple↗
PubMed1978

Genetically determined sex-reversal in 46,XY humans.

Evidence is presented for the existence of a gene, probably on the X chromosome, which prevents testis differentiation when present in 46,XY human embryos. Affected 46,XY women are not completely normal because of premature ovarian involution, as a result of which they have "streak gonads" similiar to those of 45,X women.

Disorders of Sex Development↗
PubMed1977

Diagnosis and management of the infant with genital ambiguity.

Clinical management of a child with ambiguous external genitalia requires physicians to consider the immediate management of the condition, as well as parental reactions. They must also obtain the necessary data upon which to make a diagnosis. This review summarizes the most common disorders causing genital ambiguity and suggests approaches toward delineation.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1977

Cytogenetic nomenclature.

The advantage of a standardized nomenclature is apparent in any discipline. A standardized method for designating carbon molecules in steroid chemistry facilitates communication in endocrinology; consistent staging methods permit comparison of data in oncology. Likewise, a standardized method for designating cytogenetic data facilitates communications in genetics. Therefore, investigators should adhere to the official recommendations summarized in this report.

Azure Stains↗