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Biomedical subjects

H A Gardner

Publications and source records attributed to H A Gardner.

13 recordsLinked to original sources

Glucocorticoid-dependent transformation by human papillomavirus type 16 E7 coding and 3' noncoding sequences.

The establishment of transformation of primary rodent cells by human papillomavirus (HPV) type 16 DNA requires glucocorticoid hormones (Pater et al., Nature 335, 832-835, 1988). Here we provide evidence by mutational analysis that, in the context of the hormone-regulated HPV 16 promoter/enhancer, the only protein coding sequences of HPV 16 required are those of the E7 gene. Moreover, additional sequences adjacent to the 3' end of E7 coding sequences are also essential for the establishment of the transformed phenotype. Splice donor sites, especially an E7 ORF 3' proximal one, are implicated for this cis-acting function, since specific deletion mutations of these splice sites greatly or completely reduced the frequency of transformation and the level of E7 RNA.

Animals

Absence of chromosome breakage in patients with retinoblastoma.

Mixed lymphocyte cultures were employed to assess the degree of spontaneous chromosome fragility in patients with retinoblastoma. There was no difference between the patients and their controls. If chromosome instability plays a role in the inherited tumour, more sensitive methods need be employed to elucidate it.

Chromosome Aberrations

Variation in chromosome 19.

Variations in centromeric staining of chromosome 19 appear to be an uncommon polymorphism inherited in a Mendelian manner and easily seen in G-banded cells. It should not be misinterpreted as a structural cytogenetic abnormality.

Adult

Isochromosome for the long arm of the Y in an infertile male.

A 37-year-old man investigated for infertility had bilateral atrophic testes. Cytogenetic investigations revealed a chromosome complement of 45,XO/46,Xi(Yq)/46,XY. Mechanisms for the origin of the i(Yq) are considered, and the relation of his chromosome constitution to his infertility and hypogonadism are discussed.

Adult

Amniotic fluid testosterone in the prenatal determination of fetal sex.

In the field of genetics, a rapid and accurate test for the prenatal determination of fetal sex, especially in cases of sex-linked disorders, is desirable. Amniotic fluid testosterone was measured by the radioimmunoassay technique in 37 samples obtained at saline abortion between 16 and 19 weeks' gestation. Final confirmation of fetal sex was obtained from fetal gonadal histology. In pregnancies with male fetuses, the mean amniotic fluid testosterone value of 27.6 ng. per 100 ml. was significantly higher (p less than 0.001) than the mean value of 9.6 ng. per 100 ml. found in pregnancies with female fetuses. The range for pregnancies with male fetuses was 15.5 to 41.3 ng. per 100 ml. and for those with female fetuses 5.7 to 15.1 ng. per 100 ml. With a coefficient of variation of 5 to 8% considered for the method of assay, there was an area of potential overlap from 12 to 18 ng. per 100 ml., giving a predictive error of approximately 16%. For patients in whom the results are clearly outside the area of overlap, this test is of value as a preliminary screen in the prenatal determination of fetal sex, especially in X-linked disorders.

Amniotic Fluid

Placental cultures for cytogenetic assessment in saline-aborted fetuses.

Confirmation of cytogenetically abnormal fetuses following saline abortion has been shown to be possible with the placenta as the source of viable fetal cells. The method is described in detail. In one third of cultures, only female cells were present. Differentiation between maternal and female fetal tissue when no numerical or structural cytogenetic disorder is present requires detailed analysis of fluorescently stained chromosomes for polymorphisms.

Abortion, Induced

The buccal smear: Reassessment of its usefulness.

Over a 7-year period 43 patients who underwent sex-chromatin and cytogenetic studies in the investigation of a disorder related to reproductive function were found to have abnormalities of the sex or autosomal chromosomes that could not have been detected by routine buccal smear. Therefore, testing for sex chromatin is of no value to the clinician, because full chromosome analysis must be performed irrespective of the findings from the buccal smear. However, the sex-chromatin test is an aid to the cytogeneticist in interpreting the chromosome analysis. In addition to those with amenorrhea and oligospermia or aspermia, persons with hypospadius and those to be treated with fertility drugs should undergo cytogenetic studies.

Cheek

Trisomy 18 and cyclopia.

A stillborn male infant with cyclopia, holoprosencephaly, extracephalic malformations, and trisomy 18 is described. The importance of chromosome studies in infants with severe congenital malformations is discussed.

Abnormalities, Severe Teratoid