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Biomedical subjects

T Webb

Publications and source records attributed to T Webb.

At least 91 records · Page 5Linked to original sources
PubMed1991

Clinical investigation of females with the Martin-Bell syndrome and risk assessment for carrier status.

Anthropometric measurements were made on a series of females heterozygous for the fragile-X syndrome. It was found that there were no simple series of discriminating features separating those of normal IQ from the mentally handicapped, but rather that the carriers studied represented a wide spectrum of phenotype. When measurements performed on 15 FRAXA negative, obligate carriers of normal IQ were considered separately, it was found that there were certain common phenotypic features allowing risk figures to be amended for those females at 50% risk of being a carrier but who are also FRAXA negative.

Adolescent↗
PubMed1990

Folate treatment of a boy with fragile-X syndrome.

A severely behaviourally disturbed three year old boy with the fragile-X syndrome was treated with intermittent folate therapy over a period of 2 years. No behavioural improvement was noted in this time but variations between cultural regimes for the successful detection of the fragile-X marker were observed.

Child, Preschool↗
PubMed1990

Fragile Xq27.3 in female heterozygotes for the Martin-Bell syndrome.

X inactivation studies have been carried out on lymphocytes from eight unrelated females heterozygous for the Martin-Bell syndrome. Four of these carriers were of normal IQ and four were mentally handicapped. When BrdU was used to differentiate between the active and inactive X chromosome an average of 55% of fra(X) were active in the retarded subjects, but only 27% were active in those of normal IQ. When 3H thymidine was used to differentiate between the active and inactive X chromosome, an average of 58% of mitoses from handicapped subjects and 33% of mitoses from normal subjects showed an active fra(X) in informative cells. These results are compared with previously published studies and it is concluded that the number of inactive fra(X) chromosomes calculated as a proportion of all cells scored is the same in mentally normal and mentally retarded subjects. However, the number of active fra(X) chromosomes is consistently higher in the retarded than in the normal females.

Bromodeoxyuridine↗
PubMed1989

Autoradiographic localization of [3H] gamma-aminobutyric acid in neuronal elements of the rat gastric antrum and intestine.

High-affinity uptake and localization of radiolabelled gamma-aminobutyric acid (GABA) has been examined using light microscopic autoradiography in laminar preparations and transverse paraffin sections of the rat stomach, and small and large intestine. In the presence of beta-alanine (10(-3) M), a substrate specific inhibitor of high-affinity GABA transport into glia, tritiated GABA was accumulated by a high-affinity uptake system into myenteric ganglia and a subpopulation of mucosal cells. In the small and large intestine high-affinity uptake of [3H]GABA was evident in myenteric ganglion cells, extra-ganglionic sites and in the deep muscular nerve plexus of the circular muscle layer. Such labelling could be prevented in tissue treated with the specific neuronal high-affinity uptake blocker, L-2,4-diaminobutyric acid dihydrochloride (L-DABA; 10(-3) M), and therefore represented the selective distribution of [3H]GABA uptake sites to intrinsic neuronal elements of the rat gastrointestinal tract.

Acetanilides↗
PubMed1989

Food irradiation.

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Consumer Advocacy↗
PubMed1989

The inactivation of the fragile X chromosome in female carriers of the Martin Bell syndrome as studied by two different methods.

Female heterozygotes for the fragile X syndrome show variable levels of mental handicap from normal to severely retarded. The degree to which they are affected may depend upon whether the fragile or the normal X chromosome is preferentially inactivated, but one of the problems with the use of BUdR for the study of Lyonisation in fragile-X heterozygotes is that it reduces the level of expression of the fragile site. Results obtained by this method will be biased if the suppression occurs preferentially in either the active or the inactive X chromosome. To confirm that BUdR does not preferentially cause repair of the fragile site on either the late or the early replicating X chromosome, a comparison was made between the percentage of active or early fragile-X obtained using BUdR, and that obtained using tritiated thymidine in cells from the same heterozygote.

Bromodeoxyuridine↗
PubMed1987

Children with the fragile X chromosome at schools for the mildly mentally retarded.

An investigation of children in schools for the moderately mentally handicapped in Coventry demonstrated that 29 of 259 children had a significant chromosomal abnormality. 10 of 155 boys (6 per cent) and 10 of 104 girls (10 per cent) had the fragile X syndrome. The clinical features which suggested this syndrome in males were IQ in the 50 to 70 range, head circumference greater than the 50th centile and post-pubertal testicular volume greater than the 50th centile. For both males and females, large ears were a useful sign. All children with fragile X had a carrier parent. The occurrence of mental retardation among sibs was one in two for brothers and one in four sisters. Considering all the males with fragile X syndrome resident in Coventry (this and previous studies), there were twice as many in schools for the moderately mentally handicapped as there were in schools for the severely mentally handicapped. There were as many females as males in the schools for the moderately mentally handicapped.

Cephalometry↗
PubMed1987

Studies of the parathyroid hormone gene in normal subjects, and in subjects with primary hyperparathyroidism and familial benign hypercalcaemia.

Familial benign hypercalcaemia (FBH) closely resembles primary hyperparathyroidism (PHPT) both clinically and biochemically. Using a cDNA probe for the parathyroid hormone (PTH) gene we have studied restriction fragment length polymorphisms in normal British subjects and have shown them to be similar to those found in previous studies in a German population. The pattern of inheritance of these restriction fragment length polymorphisms in a family with FBH shows that the PTH gene is not involved in the pathogenesis of the condition. Limited studies in PHPT indicate that it is unlikely that a major structural defect or rearrangement is responsible for the sporadic form of the disease.

Alleles↗
PubMed1986

Twelve families with fragile X(q27).

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.

Cells, Cultured↗
PubMed1986

Replication status of fragile X(q27.3) in 13 female heterozygotes.

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.

Bromodeoxyuridine↗
PubMed1986

Identification of interference affecting the gas-liquid chromatography analysis of valproic acid in quality control material.

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.

Chromatography, Gas↗
PubMed1985

Is it possible to make a clinical diagnosis of the fragile X syndrome in a boy?

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.

Birth Weight↗
PubMed1985

Frequency and replication status of the fragile X, fra(X)(q27-28), in a pair of monozygotic twins of markedly differing intelligence.

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.

Adult↗