Biomedical subjects
Publications and source records attributed to T Webb.
A randomized trial involving 200 transcervical chorionic villus samples taken with three different cannulas was undertaken. In terms of karyotype recovery and ease of insertion the aluminum cannula performed best although the placental site influenced the ability to recover villi for all cannulas.
Explore the source record for details and available documents.
Through a community study of boys requiring special education for the severely mentally retarded, 12 families were ascertained in which the fragile X was found to be segregating. By assiduous follow up of these families, it was found that in only four of them could male transmission be ruled out from the grandparents' or great grandparents' generation and that the segregation ratios are disturbed.
Chromosome analysis, after bromodeoxyuridine incorporation and a sequential Leishman acridine orange staining method previously described, was used to assess the percentage of early or active fragile Xs compared with the overall total in informative cells in 13 heterozygous females. The percentage thus obtained was then used to calculate the percentage of early or active fragile X that would be expected in a culture without bromodeoxyuridine, that is: percentage active fragile X divided by 100 X percentage fra(X) in standard 199 or M culture. Five females were normal and eight of below normal intelligence. In one culture pokeweed mitogen was substituted for phytohaemagglutinin and the percentage of active fragile Xs obtained was compared with that obtained with phytohaemagglutinin. In the same female the effect of addition of fluorodeoxyuridine and methotrexate on the replication ratio of the X was also investigated. R banded and G banded cells from this subject were also scanned for the deletion of Xq27.3----qter.
The matrix used to prepare control material for the Chemical Pathology Quality Assurance Programme Group of the Royal College of Pathologists of Australasia/Australian Association of Clinical Biochemists (RCPA/AACB) was investigated to identify a contaminant affecting the gas-liquid chromatography (GLC) analysis of valproic acid (VPA). The contaminant, not present in patients' sera, eluted with the octanoic acid internal standard in our GLC procedure. The compound was identified as octanoic acid. The source of this contamination could not be determined. The presence of endogenous octanoic acid in the RCPA/AACB quality control material precluded the use of octanoic acid as an internal standard.
Clinical observations were made on a series of 156 boys with severe mental retardation, before cytogenetic results were known. The clinical features that helped to distinguish the 14 boys with the fragile X chromosome from those without were: head circumference over the 50th centile, postpubertal testicular volume over the 50th centile, and an IQ between 35 and 70. If the above clinical features were all present, then the chance of finding the fragile X chromosome was 1 in 3.6, whereas the chance of finding this abnormality in any boy with severe idiopathic mental retardation, regardless of his clinical features, was 1 in 9. Two boys with fragile X syndrome did not, however, possess any of the above clinical features. Moreover, some of the other retarded boys had clinical features of the syndrome, or an X linked pedigree, but lacked the chromosome abnormality.
Chromosome analysis using conventional staining, G banding, and, after BUdR incorporation, two R banding methods, one using Hoechst and one acridine orange, were performed on lymphocytes from a pair of female monozygotic twins. The culture conditions were designed to show the presence of the fragile X (q27-28) which had previously been found to be segregating in the family. One twin was of higher than normal intelligence and the other had been diagnosed as mentally retarded. The frequency of the occurrence of the early/active fragile X compared to the overall total of informative fragile X was determined using both methods described above and was also compared with previous published data in the form of a graph showing percentage of early/active fragile X against intelligence.
The rate of traumatic early life events in 31 agoraphobic subjects with panic attacks was significantly higher than that in matched control subjects. Experience of maternal separation, parental divorce, and events occurring after the age of 4 years was significantly more common.
During the course of a population study of non-specific mental retardation in school-age males, a 13-year-old boy was ascertained. Cytogenetic studies revealed the presence of a fragile site at chromosome 22. The site was found to be both folate-dependent and heritable. The possibility that the presence of this fragile site is linked to mental retardation is discussed.
Polarography, using cylindrical platinum electrodes, proved suitable for measuring changes in the internal apical O(2) concentration of the primary root of pea (Pisum sativum L. cv Meteor) effected by KCN and/or salicylhydroxamic acid (SHAM) in the bathing medium. An electrical rootaeration analog was used to help evaluate some of the results. Concentrations of KCN </=0.05 millimolar had no significant effect. In response to 0.1 millimolar KCN, the O(2) concentration rose substantially for approximately 2 hours, then declined, and after 10 hours had frequently fallen below the pretreatment level. Such changes suggest an initial inhibition of cytochrome oxidase-mediated O(2) uptake followed by an induction of the alternative, cyanide-resistant respiratory pathway. These treatments proved nonlethal. Changes in O(2) concentration similar to those described for 0.1 millimolar KCN were observed in response to 1 and 10 millimolar KCN but these treatments were lethal and the root apex became soft and often appeared flooded. Roots survived and showed no significant responses when treated with SHAM at concentrations </=5 millimolar. However, when the alternative pathway had been (apparently) induced by 0.1 millimolar KCN, the addition of 5 millimolar SHAM to the bathing medium caused a substantial and persistent rise in the root apical O(2) concentration, suggesting that this (nonlethal) concentration of SHAM could indeed inhibit O(2) uptake via the cyanide-resistant pathway.It is concluded that while O(2) uptake normally occurs by the cytochrome pathway in the primary pea root, the alternative, cyanide-resistant pathway can be induced by 0.1 millimolar KCN.
A fourth human blood group chimaera studies in Birmingham is an example of haemopoietic (twin) chimaerism in which the subject was unaware of being a twin. Chimaerism was discovered during routine antenatal serological investigation in which it was shown that the proposita has two red cell populations, one of the rhesus genotype rr, and the other R1r. Further studies showed that she has two populations of lymphocytes, one with the female karyotype, 46XX, and the other with the male karyotype, 46XY. Skin fibroblasts were all 46XX.
Blood samples were collected from 22 patients with Huntington's chorea and from 22 matched controls. Lymphocytes were separated from aliquots of each sample and cultures set up both from these and from further aliquots of whole blood. After 24 hours, half of each culture was subjected to X irradiation. Seventy-two hours later the percentages of live lymphocytes were estimated for each half of every culture and the viability ratio calculated for each sample. The lymphocytes derived from the patients with Huntington's chorea were found to be more susceptible to X irradiation than were the lymphocytes derived from controls. This was true both for whole blood and separated lymphocyte cultures. This susceptibility was found not to be the result of the main types of medication received by the patients. The small differences between viability ratios from patients and controls and the degree of overlap makes this test unsuitable for the prediction of asymptomatic carriers of the Huntington's chorea gene.
A clinical and cytogenetic study has been made of subjects from families who have possible X linked mental retardation. The families were distinguished as those with a clinical diagnosis of Renpenning syndrome and those with other behavioural or physical abnormalities obviating such a diagnosis. All subjects with REnpenning syndrome carried a fragile Xq27-28 chromosome in more than 4% of their blood lymphocytes. In addition, two other families who did not have Renpenning syndrome but had similar clinical features also carried the fragile site Xq27-28. A female age effect was observed and one possible carrier of Renpenning syndrome exhibited the fragile X in 10% of her lymphocytes but was also mentally retarded. Subjects within the same family did not always exhibit the fragile site on a comparable proportion of their cells.
Samples of human amniotic fluid from 48 pregnancies were examined by high resolution two-dimensional gel electrophoresis and the positions of the major peptides were mapped. Many of the proteins in amniotic fluid also occur in adult and fetal serum. Three regions in the amniotic fluid maps could be defined containing peptides which were not found in adult or fetal serum. The concentration of these peptides is variable and their origin is as yet unknown. Many differences were seen between adult and fetal serum proteins.
In the course of a study of the close linkage between the gene locus for the autosomal recessive disease, Congenital Adrenal Hyperplasia (CAH), and the major histocompatibility complex (MHC), a cytogenetic survey was undertaken. In one family, where a crossover might have occurred between some loci in the MHC complex and the locus for the 21-hydroxylase gene, there was also a crossover between the MHC locus and the centromere of chromosome 6.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.