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Biomedical subjects

J R Miller

Publications and source records attributed to J R Miller.

At least 217 records · Page 12Linked to original sources
PubMed1976

Prenatal diagnosis of genetic disease in Canada: report of a collaborative study.

A study of 1223 amniocenteses carried out during 1020 pregnancies in 990 women showed that 2nd-trimester amniocentesis at about 16 weeks' gestation is a safe, accurate and reliable procedure for the diagnosis of certain classes of genetic disease when it is monitored by ultrasound, performed by a trained obstetrician and carried out in a major health sciences centre. The percentage of fetal losses (4.7%) and neonatal deaths (0.5%) during the study was not greater than in control samples for women 35 years of age and older. The best results were obtained when needles of gauge 20 or 21 were used. The use of needles of gauge 19 or larger and more than two insertions during a single amniocentesis were associated with a significantly greater frequency of fetal loss than a second or even a third amniocentesis during the same pregnancy. For 39 fetuses (3.8%) a diagnosis of a genetic abnormality was made and 23 male fetuses were found to be potentially hemizygous for an X-linked gene. There were 51 therapeutic abortions as a result of the diagnosis. Sixty-six tests (5.4%) gave an inconclusive result and seven (0.6%) gave an erroneous diagnosis; five of the latter (two false-positives and three false-negatives) resulted from the alpha1-fetoprotein test for neural-tube defects and in two cases the sex was incorrectly determined. The frequency of all chromosome abnormalities was 1:20 when the mother's age was 40 years or more and 1:60 when the mother's age was between 35 and 39 years. When a mother had previously had a child with a chromosome abnormality the risk of recurrence of such an abnormality was 1:100 when the age of the mother was 35 years or more.

Abortion, Therapeutic↗
PubMed1976

Reinvestigation of oak leaf roller sex pheromone components and the hypothesis that they vary with diet.

The sex pheromone of the oak leaf roller, Archips semiferanus, was identified as a specific blend (67:33) of trans-11- and cis-11-tetradecenyl acetates. The pheromone blend of females from a semisynthetic diet and from three oak species did not vary significantly. Males from these diets responsded in the laboratory and the field only to treatments approximating the 67 : 33 blend. These findings conflict with the hypothesis that the composition and perception of month sex pheromones vary with slight changes in diet.

Animals↗
PubMed1976

Nonintegrated plasmid-chromosome complexes in Escherichia coli.

A number of plasmid systems have been examined for the ability of their covalently closed circular deoxyribonucleic acid (CCC DNA) forms to cosediment in neutral sucrose gradients with the folded chromosomes of their respective hosts. Given that cosedimentation of CCC plasmid and chromosomal DNA represents a bound or complexed state between these replicons, our results can be expressed as follows. (i) All plasmid systems complex, on the average, at least one plasmid per chromosomal equivalent. (ii) Stringently controlled plasmids exist predominantly in the bound state, whereas the opposite is true for plasmids that exist in multiple copies or are under relaxed control of replication. (iii) The degree to which a plasmid population binds to host chromosomes appears to be a function of plasmid genotype and not of plasmid size. (iv) For the colicin E1 plasmid the absolute number of plasmids bound per folded chromosome equivalent does increase as the intracellular plasmid/chromosome ratio increases in cells starved for required amino acids or in cells treated with chloramphenicol; however, the ratio of bound to free plasmids remains constant during plasmid copy number amplification.

Chromosomes, Bacterial↗
PubMed1976

Nondisjunction in aging female mice.

Oocytes from CBA mice varying in age from 2 to 11 months were cultured to the metaphase II stage of meiosis and the chromosomes analyzed. The oocytes from three maternal age groups were compared with respect to the mean number of oocytes obtained per mouse, the frequency of maturation to metaphase II, and the frequency of numerical chromosomes abnormalities. Both the mean number of oocytes obtained per mouse and the frequency of maturation decreased markedly with maternal age. The frequency of chromosome abnormalities in the oocytes increased with maternal age from the young to the middle-aged mice but dropped off in the oldest maternal age group. No hyperploid (n + 1) oocytes were observed in the young or old group of mice, but 5.2% hyperploidy occurred in the middle-aged group. It is suggested that the lack of hyperploid oocytes in the old CBA females might be due to a threshold effect in which oocytes that are damaged by the number of univalents present at metaphase I become atretic and do not progress to metaphase II. The frequency of diploid (2n) oocytes was 1.7% and was not maternal-age dependent.

Aging↗
PubMed1976

Methods for detecting teratogenic agents in man.

At a multidiscipline international meeting sponsored by L'Institut de la Vie held at Guadeloupe in January 1974, current methods for detecting teratogenic agents were outlined and discussed. Recommendations of the participants of the conference were: recognize the limitations of the present defenses against teratogenic agents; educate the public and medical profession about the known human teratogenic agents; select for animal teratogenicity screening among new and existing agents by emphasizing substances to which the entire population will be exposed, agents to which pregnant women are exposed, viruses which are found to persist in the human fetus, and agents which have become suspect from clinical experience; recognize that nearly all compounds have a fetotoxic dose but that this does not imply teratogenicity; encourage the development of new, quick in vitro testing methods for detecting teratogenic agents; monitor for sudden increases in the frequency of specific malformations in newborn infants and in aborted fetuses; assure that expert multidiscipline committees are available to evaluate the threat when suspected teratogens are reported; improve teratology information storage and retrieval systems by record linkage of clinical data, linkage between computer systems, and universal identifier system for chemical compounds and congenical malformations; foster the exchange of data, particularly those held by the pharmaceutical industry.

Amniocentesis↗
PubMed1976

Electron capture detection of an apomorphine heptafluorobutyrate derivative at low picogram levels.

An electron capturing derivative of apomorphine was prepared by incubating the drug with heptafluorobutyric anhydride (HFBA), triethylamine and heat. Mass spectral analysis suggests that HFBA reacts with both phenolic hydroxyl groups on apomorphine to give a derivative detectable at low picogram levels. This method is sufficiently sensitive for pharmacokinetic studies in the horse and is likely applicable to other dopaminergic analogues of apomorphine.

Animals↗
PubMed1975

Prenatal exposure to oral contraceptives and transposition of the great vessels in man.

The hypothesis that female sex hormones in the first trimester of pregnancy are causally related to transposition of the great vessels (TGV) was tested by a retrospective study of 135 cases of TGV ascertained through the British Columbia Health Surveillance Registry. During 1962-1972 there was no increase in the annual incidence rates of TGV. Analysis of questionnaires completed on 58 cases revealed no definite association between inadvertent use of oral contraceptives or other sex hormones during early pregnancy and TGV.

Abnormalities, Drug-Induced↗
PubMed1975

Development of IgE and allergy in infancy.

Serum IgE levels were followed throughout the first year of life in a sample of 34 infants from atopic and nonatopic families. Their parents' serum IgE levels were also measured. Neonatal levels ranged from 0 to 10 U/ml. Half of the study group, which included a high proportion of infants from atopic families, maintained serum IgE levels below 10 U/ml until 1 yr of age. In the remainder, the serum IgE exceeded 10 U/ml before 1 yr of age, but the time of increase and the rate of increase varied from infant to infant; the sooner the IgE started to increase, the higher was the serum IgE level at 1 yr of age. The relationship of serum IgE level to the development of atopic disease and to other parameters was analyzed. Elevation of serum IgE level at or before 1 yr of age was highly correlated with atopic disease in the first 2 yr of life. The elevation preceded the manifestation of atopy.

Aging↗