Biomedical subjects
J R Miller
Publications and source records attributed to J R Miller.
The three cases of conjoined twins of Nairobi 1976-1979.
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Nonspecific X-linked mental retardation II: the frequency in British Columbia.
Data on nonspecific mental retardation in two or more sibs ascertained from the British Columbia Health Surveillance Registry are utilized to calculate the frequency of X-linked mental retardation in the population of British Columbia (B.C.). In the 1950-1969 birth cohort there are 107 sibships with only males affected and 35 sibships with only females affected giving an excess of 72 male-affected sibships. Family histories of the sibships with two more more mentally retarded males provide evidence that the mothers of the excess of male-affected sibships are carriers of X-linked mental retardation. Thus, a frequency of 1.83 per 1,000 males for X-linked mental retardation and carrier frequency of 2.44 per 1,000 females are calculated. This frequency can account for all the excess of males in the population who are affected with nonspecific mental retardation. We estimate that seven to 19 X-linked genes exist to cause nonspecific mental retardation, and that the frequency of the marker-X chromosome, associated with X-linked mental retardation in some families, may be 0.92 per 1,000 male births.
Embryo transfer in the analysis of teratological responses of mice: a critical examination.
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Recommendations on experimentation with children: some differences in Canadian and American approaches.
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R-factor responsible for an outbreak of multiply antibiotic-resistant Klebsiella pneumoniae.
Seven serotypes of Klebsiella pneumoniae isolated from different patients demonstrated resistance to the same eight antibiotics. A plasmid carrying resistance determinants to these antibiotics and mercury salts could be transferred in toto to a plasmidless strain of Escherichia coli. All E. coli transconjugants showed the same antibiotic resistance pattern. Digestion with restriction endonucleases yielded patterns that were identical for each of the R-factor transferred from the multiply resistant serotypes. Moreover, deoxyribonucleic acid-deoxyribonucleic acid hybridization demonstrated identity between the probe, pMAC20 (an R-factor from one serotype), and all R-factors isolated from the multiply resistant strains of K. pneumoniae and the E. coli transconjugants tested.
Amyotrophic lateral sclerosis: search for poliovirus by nucleic acid hybridization.
Radioactive-labeled complementary DNA (cDNA) probes specific for either poliovirus type I or type II were hybridized with cellular RNA from the brains of patients dying of amyotrophic lateral sclerosis. In 11 brains examined, the percentage of hybridization for either polio type was the same as the percentage in normal brains. Although hybridization is a sensitive method for detection of viral genome material in infected cells, inability to detect viral nucleic acid by current techniques does not preclude the presence of viral genetic material in the tissue examined.
Prolonged intracerebral infection with poliovirus in asymptomatic mice.
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Problems of single-parent families.
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Antenatal diagnosis of neural tube defects in Canada: extension of a collaborative study.
Experience with the diagnosis of neural tube defects from alpha1-fetoprotein (AFP) concentrations in amniotic fluid is reported from a prospective study of five laboratories testing for 13 Canadian genetic centres. The results of the study indicate that antenatal diagnosis of open neural tube defects is being carried out effectively in Canada (in 99.2% of cases the AFP measurements were interpreted correctly). Amniocentesis should be recommended to women at high risk for having a child with a neural tube defect (i.e., those who have a child, a parent or a sibling with a neural tube defect). The rate of neural tube defects in 182 high-risk pregnancies was 2.2% for an open defect and 1.1% for a closed defect, whereas the rate in 673 pregnancies in which amniocentesis was being performed for other reasons was 0.3%. This suggests that the AFP concentration should be measured in any sample of amniotic fluid collected for other reasons (usually fetal karyotyping). There were three instances of false-negative results, for a rate of 0.4%. Two closed neural tube defects were not detected; this limitation of the test has also been found by others. One of the six fetuses with an open neural tube defect, who died in utero, had a large myelocele in the neck that was not recognized. There were also four instances of false-positive results, for a rate of 0.5%. The findings suggest that AFP values that are more than 2 but less than 7 standard deviations (SDs) above the mean may indicate a neural tube defect, and that values 7 or more SDs above the mean very likely indicate such a defect, although other reasons for such high values (e.g., fetal erythrocytes in the amniotic fluid, intrauterine death and mistaken gestational age) must be ruled out by other methods.
Canadian college of medical geneticists.
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Apparent validity of alternative survey methods.
A comparison of results using three methods of obtaining the same survey data is reported. The assumption is made that in relation to a question for which there is a socially desirable response, e.g., use of seat restraints for children, those reporting nonuse or infrequent use are giving truthful answers. In an experiment in health education, follow-up assignments were made randomly, one third being interviewed face-to-face, one third by telephone, and the rest by a postal questionnaire. There were no significant differences by method of follow-up in the scores reflecting reported changes in behavior following instruction. Both the telephone and mail methods, however, appear to yield a higher proportion of "truthful", i.e., socially undersirable, responses; 30.4% of those contacted by telephone admitted to not using a restraint on the last trip, compared with 26.3% of those questioned by mail and 17.5% in a household interview. It is recommended that careful consideration be given to these alternative methods of obtaining data, particularly in view of their lower cost and possibly greater validity.
Optimization of parameters in protein nitrogen unit precipitation procedure for allergenic extracts.
This work establishes the optimum conditions for the protein nitrogen unit (PNU) phosphotungstic acid (PTA) precipitation procedure for allergenic extracts. The volume of extract analyzed, the dilution of the extract prior to precipitation, the percent PTA in the precipitating solution, the washing of the precipitate, and the volume of concentrated HCl initially added to the extract were optimized, as they were found to be the factors which affected the amount of PTA precipitate obtained. Varying the digestion time, the digestion temperature, and the percent HCl in the 15% PTA precipitating solution did not cause detectable differences in the PNU values of the extracts studied.
Monozygotic twinning and structural defects.
An excess of structural defects occurs in monozygotic twins compared in dizygotic twins or singletons. The excess is composed of three categories of defects. The first includes defects which are part of the MZ twinning, such as conjoined twins and some amorphous twins. In addition, all early embryonic malformations and malformation complexes such as sirenomelia mc. holoprosencephaly mc. and anencephaly mc are increased in MZ twins. The reason for this association is considered to be the common etiology for both the MZ twinning and the early malformation problem. MZ twins provide an excellent model for appreciating the spectra of particular malformation complexes, since the twins often have different gradations in severity of the same type of structural defect. The finding of both discordant and concordant MZ twins with Goldenhar, de Lange, and Rubinstein-Taybi syndromes suggests that these "syndromes" might be early malformation complexes. The other two categories are considered secondary to the MZ twinning process. The most unique category results from any vascular interchange between the MZ twins. Depending on their nature, vascular connections may give rise to reverse flow with acardiac status in one twin during early development, or to vascular disruptions from a deceased co-twin with intravascular coagulation causing embolization in the surviving co-twin. The latter defects may include microcephaly, porencephalic cysts, hydranencephaly, intestinal atresia, aplasia cutis, and limb amputation. Unequal growth may occur as a result of artery to vein placental anastomoses. The final category is deformations due to crowding in utero during late gestation. These do not differ from those in DZ twins.
Evidence for secondary structure in poliovirus virion RNA demonstrated by antibodies against double-stranded RNA.
Poliovirus particle RNA has been considered to have little secondary structure. Specific binding of poliovirion RNA by antibodies against double-stranded RNA (dsRNA) has been confirmed and further characterized by a radioimmunoassay using Staphylococcus aureus protein A to precipitate the nucleic acid-antibody complex. Competitive binding studies between virion single-stranded RNA (ssRNA) and poly(I).poly(C) demonstrated that the dsRNA effectively inhibited binding of radiolabelled poliovirion RNA by the anti-dsRNA antibodies but the virion RNA was a poor competitor of radiolabelled ds RNA. This indicates that both RNAs reacted with the same species of antibodies in the sera, but avidity of the antibodies for dsRNA was greater than for the poliovirion RNA.
Clinical and genetic aspects of seizure disorders prevalent in an isolated African population.
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Biochemical characterization of nonintegrated plasmid-folded chromosome complexes: sex factor F and the Escherichia coli nucleoid.
The existence of nonintegrated plasmid-chromosome complexes has been deduced in previous work from the cosedimentation of covalently closed, circular plasmids with host folded chromosomes. In the present work, it is shown that about 70 to 90% of the covalently closed, circular F deoxyribonucleic acid could be released in vitro from chromosome complexes by ribonuclease treatment but not by protease, Sarkosyl, or ethidium bromide. Consistent with the in vitro studies, Escherichia coli cells treated for 5 min with rifampin, an inhibitor of ribonucleic acid initiation, released upon lysis 90% of their plasmid deoxyribonucleic acid as freely sedimenting molecules.