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Biomedical subjects

M W Steele

Publications and source records attributed to M W Steele.

At least 55 records · Page 3Linked to original sources
PubMed1984

Are the occasional aneuploid cells in peripheral blood cultures significant?

Cytogenetic results of 1,500 consecutive clinical cases from a young population were analyzed for rare cells with hypermodality (greater than or equal to 47 chromosomes) or hypomodality (less than or equal to 45 chromosomes). Such instances of non-modal chromosome gains or losses were random relative to referral diagnosis or modal karyotype. However, chromosome loss was correlated with size, smaller chromosomes being lost more frequently (correlation coefficient = 0.794). Sex chromosome gain or loss in vitro was of particular interest since mosaicism in vivo is frequently found in patients presenting with manifestations of Turner or Klinefelter syndrome. Cases with a referral diagnosis of sex chromosome abnormality showed no increased gain or loss of an X or Y chromosome when compared to other types of clinical cases. Our analyses suggest that when one non-modal cell is found with a gain or loss of a chromosome relevant to the referral diagnosis, then the results on a count of 40 cells should differentiate in vitro artifact from probable in vivo mosaicism with 95% degree of confidence.

Aneuploidy↗
PubMed1984

Multiple exostotic hypochondroplasia: syndrome of combined hypochondroplasia and multiple exostoses.

This is a report of a family with major focus on the daughter who was of short stature. The mother had hypochondroplasia and the father had multiple exostoses. The daughter's skeletal roentgenograms show features of both hypochondroplasia and multiple exostoses. The roentgenographic, clinical and genetic aspects of these skeletal dysplasias are reviewed and hypochondroplasia is contrasted with achondroplasia. The genetic and counseling implications of the association of hypochondroplasia and multiple exostoses are discussed.

Child, Preschool↗
PubMed1984

The level of 6-phosphogluconate dehydrogenase (6-PGD) activity in a patient with 1p terminal deletion suggests that the gene locus is not distal to sub-band p36.3 on chromosome 1.

A rare case of chromosome 1p deletion is reported in a mentally retarded male infant with a derived chromosome: 45,XY,-1,-13,tdic(1;13)(1qter----1p36.2::13p11.2----++ +13qter). Parental chromosomes were normal. Since the patient's 6-PGD specific activity was in the normal range, it is probable that he retained both 6-PGD alleles. Consequently, if a dosage affect exists, then the locus for 6-PGD must be proximal to 1p36.3.

Adult↗
PubMed1984

In vitro reversal of fragile-X expression by exogenous thymidine.

A virtually thymidine free medium was used to test the effects of exogenous thymidine on lymphocyte expression of the fragile-X. De novo pathway thymidylic acid synthesis in the cells was blocked by FUdR. Our results suggest that in vitro exogenous thymidine is directly responsible for suppressing expression of the fragile-X. More importantly, delayed addition of exogenous thymidine can negate fragile-X expression after it has first been induced by FUdR.

Culture Media↗
PubMed1984

Prader-Willi syndrome in black females.

Reports of Black females with Prader-Willi have been rare. This communication describes two Black females with Prader-Willi syndrome. Chromosome analysis revealed a small deletion of the proximal portion of a chromosome 15 in one case and apparently normal chromosomes in the other.

Adolescent↗
PubMed1983

A simplified PKU gene carrier detection test using fasting blood.

By fluorometric analysis of fasting phenylalanine and tyrosine plasma levels, we could discriminate classic gene PKU carriers from non-carriers with 99% confidence in 67 of 74 adults. Results on the remaining seven subjects were non-discriminating. However, we could not determine their carrier status by other accepted testing parameters either (such as phenylalanine dosing). In contrast to the latter, our method: (1) allows for 90% of the population a relatively accurate but more benign test for carriers of the classical PKU gene (requiring only fluorometry on a single fasting blood specimen); (2) identifies the remaining 10% of the population who require the more cumbersome-noxious testing by phenylalanine dosing.

Fasting↗
PubMed1982

A controlled retrospective follow-up study of the impact of genetic counseling on parental reproduction following the birth of a Down syndrome child.

Twenty-three couples who had received genetic counseling after the birth of a Down Syndrome child (DSC) were closely match-paired by race, religion, maternal age, paternal occupation, parental education and sex sibship order of the DSC with 23 non-counseled couples who had also had a DSC. When evaluated at least 1 1/2 years after the birth of the DSC or the genetic counseling, there were no significant differences between counseled and non-counseled couples in knowledge of general genetics or recurrent risks for Down Syndrome, initiation of subsequent pregnancies, or utilization of prenatal diagnosis. Knowledge of general genetics and recurrent risks for Down Syndrome among our post-counselees was poorer than that of two published immediate follow-up reports. Although 18 of 46 couples initiated at least one more pregnancy after the birth of their DSC, only three couples (2 counseled; 1 non-counseled) utilized prenatal diagnosis by amniocentesis.

Adult↗
PubMed1982

Lack of impact of undergraduate genetic courses on the teaching of medical genetics.

The impact of undergraduate genetic courses on the academic performance of first-year medical students in the medical genetics course at the University of Pittsburgh School of Medicine was evaluated over a period of 9 years. Comparisons were made between medical students who had taken a formal undergraduate course in genetics and those who had not. Little if any differences were found in the academic performance in the medical genetics course between these two groups of students. Perhaps the design of undergraduate courses in genetics should be re-evaluated to give more depth to the medical student's preparation for appreciating the significance of genetics in normal and abnormal human variation.

Education, Medical, Undergraduate↗
PubMed1981

Meiotic consequences of pericentric inversions of chromosome 13.

A case is presented demonstrating meiotic consequences of inheritance of a pericentric inversion, inv(13)(p13q21), and suggesting, together with other similar reports reviewed, that certain manifestations (highly arched palate, long philtrum, polydactyly, microphthalmia, and capillary hemangiomata) result from duplication of the distal 13q while others (cleft lip/palate, scalp defects, congenital heart disease) result from duplication of the proximal 13q.

Adult↗
PubMed1981

Incorporation of bacteriophage DNA into the genome of cultured human lymphocytes.

After exposure of phytohemagglutinin-stimulated human lymphocytes to high doses of tritiated-thymidine labelled phi X-174 or T2 bacteriophage, label from the phage genome became incorporated into lymphocyte DNA. Exposure to bacteriophage DNA, whether biologically active, inactive, or fragmented, had a depressive effect on lymphocyte DNA replication. Incorporation of label from phage DNA into the lymphocyte DNA, however, was maximum for biologically active phage.

Cells, Cultured↗
PubMed1980

Effects of physicians' early parental counseling on rearing of Down syndrome children.

A survey of the feelings of 37 couples with a school-age Down syndrome child born since 1970 suggested a diminished influence of physicians' early counseling on parental decisions, attitudes, and rearing practices respecting their affected child. In contrast, undefined "personal feelings," own research, and input from community parent groups (such as the Pennsylvania Association for Retarded Citizens) were major influences. Parental decisions on further reproduction after the birth of a Down syndrome child was based less on perception of genetic risks than on concern for the care needs of their affected child.

Attitude to Health↗
PubMed1977

Meiotic consequences of an intrachromosomal insertion of chromosome No 1: a family pedigree.

In three generations of the proband's patrilineal relatives, 14 subjects were found to be carriers of a "shift" insertional chromosome No. 1 (46XX or XY, ins(1)(p32q25q31)). The proband and three female relatives, who were mild to moderate mental retardates with minor congenital anomalies, were trisomic for the insertional segment, (1)q25q31. Another subject, who was a markedly immature female abortus with congenital abnormalities, was found to be monosomic for this same chromosomal segment. The cytogenetic evidence suggests that each of these unbalanced recombinant progeny was the result of a single crossing over in the noninsertional loop of a paternal pachytene bivalent of the balanced insertional chromosome No. 1.

Abnormalities, Multiple↗
PubMed1976

Trisomy of chromosome 20.

A neonate with ususual facial features and multiple congenital malformations expired at 4 hours of age. An autopsy revealed severe anomalies of the gastrointestinal system and spinal dysplasia. Cytogenetic evaluation of fibroblasts cultured from a lung biopsy revealed a karyotope of 47,XX,+20.

Abnormalities, Multiple↗