Search PubMed⌕ Search

Biomedical subjects

T Webb

Publications and source records attributed to T Webb.

At least 55 records · Page 3Linked to original sources
PubMed1998

Affective psychosis and Prader-Willi syndrome.

Previous studies have demonstrated that maladaptive behaviours are common amongst adults with Prader-Willi syndrome (PWS). Case reports have also previously demonstrated that psychosis can occur amongst adults with PWS. The present study was undertaken in order to gain a better understanding of the psychopathology of the psychosis of PWS. Twenty-three out of 25 adults identified with PWS living in Northamptonshire, UK, agreed to participate. Comprehensive psychiatric assessments (using the PPS-LD), and measures of adaptive and maladaptive behaviours (using the AAMR-ABS) were completed. Comparisons were made for the prevalence of psychiatric disorders against those from a previous epidemiological study of adults with intellectual disability of other aetiologies from a neighbouring county. The PWS group was found to have higher rates of affective disorders (a point prevalence of 17.4%), in which psychotic symptoms were common, but similar rates of schizophrenia/delusional disorders (4.3%) compared with the comparison group. Behaviour disorders were also common. Surprisingly, none of the PWS group was found to have generalized anxiety or phobic disorders. The diagnostic criteria for the episodes including psychotic symptoms are explored. The high rates of affective disorders is of clinical (i.e. treatment) importance as well as being of academic interest with regard to the genetics of psychiatric disorders.

Adult↗
PubMed1998

Linkage analysis in Rett syndrome families suggests that there may be a critical region at Xq28.

A whole X chromosome study of families in which Rett syndrome had been diagnosed in more than one member indicated that the region between Xq27 and Xqter was the most likely region to harbour a gene which may be involved in the aetiology of the disease. Further, more detailed studies of Xq28 detected weak linkage and a higher than expected sharing of maternally inherited alleles. It is suggested that there may be more than one gene involved in the aetiology of this syndrome, particularly as the very rare families in which more than one girl is affected often show variable clinical symptoms.

Alleles↗
PubMed1998

Pneumothorax and pneumomediastinum during colonoscopy.

A case of bowel perforation during diagnostic colonoscopy is reported. This resulted in the sudden appearance of massive subcutaneous emphysema of the neck, causing acute upper airway obstruction which necessitated urgent endotracheal intubation. Large bilateral pneumothoraces and pneumomediastinum were also present.

Aged↗
PubMed1997

Protease digestion studies of an equilibrium intermediate in the unfolding of creatine kinase.

Protease digestion experiments have been used to characterize the structure of an equilibrium intermediate in the unfolding of creatine kinase (CK) by low concentrations (0.625 M) of guanidine hydrochloride (GdnHCl). Eighteen of the major products of digestion by trypsin, chymotrypsin and endoproteinase Glu-C have been identified by microsequencing after separation by SDS/PAGE and electroblotting on poly(vinylidene difluoride) membranes. The C-terminal portion (Gly215 to Lys380) was much more resistant to digestion than the N-terminal portion (Pro1 to Gly133), although the area most sensitive to proteolysis was in the middle of the CK sequence (Arg134 to Arg214). These experiments are consistent with the two-domain model for the CK monomer. The structure of the intermediate is proposed to consist of a folded C-terminal domain and a partly folded N-terminal domain separated by an unfolded central linker. Protease susceptibility is clustered within two N-terminal regions and one central region. These regions are evidently exposed as a result of the partial unfolding and/or separation of the N-terminal domain. Further evidence for the structure of this intermediate comes from gel filtration studies. Treatment of CK with 0.625 M GdnHCl resulted in slow aggregation at 37 degrees C, but not at 12 degrees C, a phenomenon previously reported for phosphoglycerate kinase. The aggregation did not occur at higher GdnHCl concentrations and was unaffected by a reducing agent. It is proposed that aggregation is a consequence of non-specific interactions between hydrophobic regions, possibly domain/domain interfaces, which become exposed in the intermediate.

Amino Acid Sequence↗
PubMed1996

Prevalence of fragile X syndrome.

The much-quoted prevalence figure of 1:1,000 males for fragile X syndrome is an overestimate in a mixed ethnic population. A reexamination of the individuals from whom those data were derived using molecular diagnostic techniques demonstrates a more realistic figure of 1:4,000 males.

Female↗
PubMed1996

Long-term benefits of aggressive treatment for primary colorectal cancer.

The long-term follow up of 128 colorectal cancer patients is reported. Seventy-nine percent (101/128) of the patients had curative resections: 70 patients had radical lymphadenectomies with wide removal of tumor-adjacent nodes, and 31 patients had standard resections. The 5-year overall survival rates for Dukes' stage B and C patients and for all rectosigmoid cancer patients significantly favored radical resection (60% vs. 38%, 57% vs. 29%, respectively, P < 0.05). Tumor-free survival rates were also higher after radical lymphadenectomy but did not reach statistical significance. Eleven percent (14/128) of the patients required multiorgan resections, and/or preoperative radiation to render fixed cancers resectable, and these patients had a 10-year tumor-free survival rate of 45%, compared to zero % 5-year survival for the 27 patients who underwent palliative procedures (P < 0.01). These results confirm that many colorectal cancer patients will be cured with aggressive treatment and they support the need for a controlled trial for evaluation of lymphadenectomy for this disease.

Adult↗
PubMed1996

Maladaptive behaviour in Prader-Willi syndrome in adult life.

Thirty adults with Prader-Willi syndrome (PWS) were compared with 30 adults with non-specific learning disability matched for age, sex and severity of mental retardation. Maladaptive behaviour was assessed with the Aberrant Behavior Checklist (ABC), a 58-item structured interview which rates behaviours from 0 (not a problem) to 3 (severe problem) and which yields five factors (I) irritability, agitation; (II) lethargy, withdrawal; (III) stereotypic behavior; (IV) hyperactivity, non-compliance; and (V) inappropriate speech). The PWS sample had significantly higher factor I (P < 0.001) and factor V (P < 0.05) scores. The PWS sample had mean scores above 1 for 17 ABC items; the contrast subjects had no mean scores above 1. The factor I scores for the PWS sample were similar to those of inpatients in hospital facilities for adults with mental retardation and mental illness or severely challenging behaviour. The results support previous work, and extend it by suggesting that temper tantrums, self-injury, impulsiveness, lability of mood, inactivity and repetitive speech are characteristic behaviours in PWS in adult life. Studies of the reasons for heterogeneity in behaviour are now needed.

Activities of Daily Living↗
PubMed1996

A comparative study of X-inactivation in Rett syndrome probands and control subjects.

X-inactivation has been studied in a series of monozygotic female twins and their female relatives by a PCR method which detects methylation at the androgen receptor locus (HUMARA). The results obtained are compared to those from an earlier study employing probe M27 beta which detects locus DXS255. Analysis of X-inactivation in girls with Rett syndrome and their mothers by four different methods did not indicate a direct relationship between non-random inactivation of the X-chromosome and the presence of the disease with the exception that any skewing detected in the probands tended to favour the preferential inactivation of the paternally inherited X-chromosome. No evidence for the involvement of uniparental disomy in the etiology of the disease was found.

Adolescent↗
PubMed1995

Aortofemoral bypass via transperitoneal approach.

The transperitoneal route remains the most widely used approach to the infrarenal abdominal aorta. The specific indications and techniques are reviewed in full detail. Special circumstances that require modifications of the standard operative approach are presented. Finally, current and expected results of aortofemoral bypass are discussed.

Anastomosis, Surgical↗
PubMed1995

Operative adjuncts for distal revascularization.

The performance of distal arterial bypass procedures in poor outflow situations may require adjunctive techniques to maximize short- and long-term patency. The rationale and technique for the most commonly used modifications are presented along with the indications for use.

Arterial Occlusive Diseases↗
PubMed1995

Alterations in replication timing of X-chromosome bands in Rett syndrome.

A cytogenetic study has been carried out on 30 girls affected with Rett syndrome, 35 of their family members and 25 unrelated healthy control females. Karyotyping at the 850 band level revealed no detectable chromosome abnormalities in either the affected girls or their families. Observations on the sequence of the appearance of early replicating bands on both the active and the inactive X-chromosome demonstrated the same replication patterns in all of the groups investigated with the exception that band Xp21 appeared with greater frequency in the Rett syndrome cells. A degree of variation was detected both between and within the subjects when the timing of the latest bands to replicate was investigated for the active X, but the same consensus order was obtained for all groups. A comparable number of elongated X-chromosomes was found in the girls with Rett syndrome (8%) when compared to their mothers (12%) when synchronized cells were treated with a short pulse of BrdU. If a disturbance in X-inactivation does contribute to the aetiology of Rett syndrome, it is at a level which is not detected by observations on the relative timing of replication of chromosome bands.

Chromosome Aberrations↗
PubMed1995

A clinical, cytogenetic, and molecular study of 40 adults with the Prader-Willi syndrome.

A clinical, cytogenetic, and molecular study has been carried out on 40 adults with a firm diagnosis of Prader-Willi syndrome. A cytogenetically detectable deletion was observed in 58% while further subjects had a deletion which was detectable by molecular methods only, giving a total of 76%. Four cases of maternal uniparental disomy (UPD) were all female. Three of them were heterodisomic while the fourth was isodisomic. Two male probands were heterozygous at all loci tested yet did not have UPD. Although methylation studies showed that one of them had a single band using probe PW71, the other one had two bands. Psychiatric studies suggest that females with maternal UPD are indistinguishable psychologically from those with a paternal deletion in 15q11q13.

Adolescent↗
PubMed1994

Sister chromatid exchange in families with Angelman or Prader-Willi syndrome.

Using estimation of numbers of sister chromatid exchanges arising in 15q11q13 as a measure, comparisons of the stability of the Prader-Willi syndrome critical region have been made. The groups studied included probands with Prader-Willi or Angelman syndromes either with or without a cytogenetically visible deletion in 15q11q13, their parents, specifically those parents who had passed on the homologue which had become deleted, and a control group. No significant differences were found between any of the four groups, indicating that there was no increase in the instability of the PWSCR region as measured by sister chromatid exchange.

Angelman Syndrome↗