PubMed Health⌕ Search

Biomedical subjects

L Wheeler

Publications and source records attributed to L Wheeler.

8 recordsLinked to original sources
PubMed1975

Heterochromatic chromosomes and satellite DNAs of Drosophila nasutoides.

Drosophila nasutoides is distinguished from other Drosophila species in that the metaphase karyotype shows a pair of very large V-shaped chromosomes. With Giemsa, a distinctive C-banding pattern is revealed along the arms of this large chromosome, indicating a largely heterochromatic nature. Furthermore, the banding patterns of the arms are symmetrical, indicating that it is an iso-chromosome. A comparison between the metaphase karyotype and polytene chromosomes suggests that the large V chromosome appears as the dot chromosome in polytene squash. One autosome has twice the arm length of typical Drosophila polytene chromosomes and arose either by centric fusion and a pericentric inversion, or by translocation connecting distal ends with a subsequent loss of one centromere. This chromosome appears to have a short arm which ectopically pairs with the proximal region of the long arm, representing a duplication of about ten bands. When the nuclear DNA is examined by neutral CsCl gradient, four satellites are observed. As much as sixty percent of the total DNA appears as satellites in the lysate of larval brains. No satellite was detectable in the lysate of salivary glands. These observations led us to suggest that the heterochromatic nature of the large V chromosome is due to the presence of all four satellites in this chromosome and that this large chromosome appears as the dot because of the under-reduplication of the satellites during polytenization.

Animals↗
PubMed1975

Age-adjusted analysis of insulin responses during normal and abnormal glucose tolerance tests in children and adolescents.

This report analyzes age-specific glucose (PG) and immunoassayable insulin (IRI) responses during oral glucose tolerance testing (OGTT) and examines test results in children and adolescents with OGTT abnormality using the age-appropriate control data. Controls' (n = 93) and patients' (n = 63) results were compared on the basis of statural age (SA) at the time of testing. Control tests (n = 101) showed significant positive correlation of fasting and four-hour postingestion PG with SA (p less than 0.001), but mean area under the PG curves did not vary between the SA groups (I--18.69 months, II--70-131 months, III--132+ months). The absence of differences of other sampling times permits uniform diagnostic criteria for this age group. IRI was positively correlated with SA at all testing times, and mean levels differed significantly between each SA group at every sampling time; the mean areas under the IRI curve also differed significantly between SA groups as did the mean ratios of IRI area to PG area (group I--0.2639 +/- 0.0175 S.E.M., group II--0.3864 +/- 0.0235, group III--0.6262 +/-0.0491). Patient tests (n = 110) were separated into normal (N), borderline (B), and chemical-diabetic (C) for each SA group. IRI means were above control data for each test type in each SA group at all sampling times; one fourth of these differences were significant. IRI responses also increased within each SA group from N to B to C tests. Mean IRI areas and IRI area to PG are mean ratios were higher than in controls, and this difference was greatest with the most abnormal (C) test type in each SA group. A subgroup of three patients who had low IRI responses from the outset and developed overt diabetes in one to three years was excluded from the analysis. In contrast to apparent relative insulin inefficiency with normal maturation and with chemical diabetes, they had exceptional responsiveness to their low IRI levels. Variable involvement of alpha as well as beta cells in the pathophysiology of diabetes is suggested as one explanation for these paradoxic observations. Changing receptor affinity might also be implicated.

Adolescent↗
PubMedDate not supplied

What is a module?

Explore the source record for details and available documents.

Curriculum↗