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Biomedical subjects

D A Waller

Publications and source records attributed to D A Waller.

At least 19 recordsLinked to original sources
PubMed1992

The frequency of uniparental disomy in Prader-Willi syndrome. Implications for molecular diagnosis.

BACKGROUND: Prader-Willi syndrome is a genetic disorder characterized by infantile hypotonia, obesity, hypogonadism, and mental retardation, but it is difficult to diagnose clinically in infants and young children. In about two thirds of patients, a cytogenetically visible deletion can be detected in the paternally derived chromosome 15 (15q11q13). Recently, patients with Prader-Willi syndrome have been described who do not have the cytogenetic deletion but instead have two copies of the 15q11q13 region that are inherited from the mother (with none inherited from the father). This unusual form of inheritance is known as maternal uniparental disomy. Using molecular genetic techniques, we sought to determine the frequency of uniparental disomy in Prader-Willi syndrome. METHODS: We performed molecular analyses using DNA markers within 15q11q13 and elsewhere on chromosome 15 in 30 patients with Prader-Willi syndrome who had no cytogenetically visible deletion. We also studied their parents. Three patients with Prader-Willi syndrome who had a cytogenetic deletion served as controls. RESULTS: In 18 of the 30 patients without a cytogenetic deletion (60 percent), we demonstrated the presence of maternal uniparental disomy for chromosome 15 and its association with advanced maternal age. In another eight patients (27 percent), we identified large molecular deletions. The remaining four patients (13 percent) had evidence of normal biparental inheritance for chromosome 15; three of these patients were the only ones in the study who had some atypical clinical features. CONCLUSIONS: In about 20 percent of all cases, Prader-Willi syndrome results from the inheritance of both copies of chromosome 15 from the mother (maternal uniparental disomy). With the combined use of cytogenetic and molecular techniques, the genetic basis of Prader-Willi syndrome can be identified in up to 95 percent of patients.

Adult↗
PubMed1992

A comparative trial of aztreonam versus gentamicin in the treatment of urinary tract infections.

A prospective, randomized trial was conducted to compare the efficacy of aztreonam, a monobactam antibiotic, and gentamicin in the treatment of serious urinary tract infections. Fifty-five patients with a suspected or confirmed infection were randomized, 28 received aztreonam and 27 received gentamicin. Both antibiotics had a high clinical response rate (aztreonam 92%, gentamicin 85%). However, the duration of treatment was significantly shorter (p = 0.037, Wilcoxon Rank Sum Test) when aztreonam was used. There were no cases of toxicity with either antibiotic but 5 patients who received gentamicin required dose alteration. Aztreonam is well tolerated and is no less effective than gentamicin in the treatment of urinary tract infections and has advantages in convenience of use and duration of treatment.

Adult↗
PubMed1992

The use of transoesophageal echocardiography for detecting early recurrence of atrial myxoma.

A comparison between praecordial and transoesophageal cross-sectional echocardiography was undertaken in the follow-up of 14 patients who had previously undergone surgical excision of atrial myxoma. The mean interval between surgery and follow-up was 39 months. Evidence of recurrent tumour was seen in two patients by transoesophageal echocardiography but went undetected in one of these using the praecordial approach. Clear visualisation of the atria and interatrial septum was possible in all remaining cases using transoesophageal echocardiography and this allowed confident exclusion of tumour recurrence. Using praecordial echocardiography, technically inadequate studies meant that this was not possible in 4 patients. The significant late recurrence rate of excised atrial myxomas, emphasises the need for serial, postoperative echocardiographic studies. Praecordial echocardiography may be unreliable in the detection of recurrent atrial myxoma in its early stages and for this reason transoesophageal echocardiographic follow-up is justified in high risk patients.

Echocardiography↗
PubMed1992

Repair of asymptomatic aortic valve disease during other cardiac surgery.

Repair of asymptomatic aortic valve disease was performed in 12 patients (9 female, 3 male, mean age 57.5 years) undergoing other cardiac surgery. Stenosis was the predominant aortic valve lesion in 7 (group A) with a mean gradient of 33.4 mmHg and regurgitation of mean grade 1.4 was predominant in 5 (group B). Cusp debridement +/- commissurotomy was performed in 9; commissural resuspension in 6 and repair of cusp perforation in 2. Perioperative transoesophageal echocardiography was used to assess the adequacy of repair in 4 patients. Prospective precordial echocardiographic follow-up is complete (mean 4.3 months). In group A there has been a significant reduction is peak aortic pressure gradient (33.4 vs 22.1 mmHg, p less than 0.05) and in cusp thickness (2.25 to 1.64 mm, p less than 0.05). In group B the degree of incompetence has improved in 3 of the 5 patients. Three patients have worsened valve disease following repair; in all these there was mixed valve disease of rheumatic origin. Aortic valve repair of asymptomatic disease during other cardiac surgery is a feasible technique which does not accelerate the disease process in the short term. Long-term follow-up is in progress to assess the prognosis of this preventive intervention.

Adult↗
PubMed1992

Cognitive patterns in school-age children with end-stage liver disease.

Although children with end-stage liver disease (ESLD) have been found to have cognitive delays, the relationship between patterns of cognitive function and diagnostic category, age of onset, duration and severity of disease has not been assessed before transplantation. Verbal and performance IQ (VIQ, PIQ) scores and scores on Bannatyne's cognitive factors for 43 children with ESLD were compared with those of 15 control children with cystic fibrosis (CF) and with existing normative data. Children with biliary atresia had deficits in PIQ, spatial and sequential scores. Children with alpha-1 antitrypsin deficiency did not differ significantly from CF controls but did show deficits compared with normative data. Children with onset of disease in the first year of life had deficits on all cognitive measures compared with both control groups. In contrast, children with later onset differed from the normative population only on VIQ and the acquired knowledge factor. In multiple regression analyses, duration of disease and indexes of liver dysfunction combine to predict cognitive scores. These preliminary findings suggest that children with early onset of liver disease are at high risk for cognitive impairment.

Biliary Atresia↗
PubMed1991

Crystallization and preliminary X-ray studies of annexin IV (endonexin), a calcium-dependent phospholipid-binding protein.

Annexin IV (endonexin) has been purified from chicken liver and crystallized by the vapour diffusion method. Crystals which diffract to at least 2.2 A have been obtained. They belong to space group R3 and have unit cell dimensions of a = b = 99.4 A, c = 96.2 A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees. There is one molecule of 32,500 Da per asymmetric unit.

Animals↗
PubMed1991

Emotional adaptation in children after liver transplantation.

The emotional adaptation of 25 children who had undergone successful liver transplantation at least 1 year previously was evaluated and compared with that of a control group of 26 children with diabetes mellitus, matched for age, gender, and socioeconomic status, and with reported normative values. With the use of parent- and self-report measures, emotional adaptation was assessed in terms of behavioral adjustment (Child Behavior Checklist), depressive experiences (Children's Depression Inventory), anxiety (State-Trait Anxiety Inventory for Children), and self-concept (Piers-Harris Children's Self-concept Scale). Similar variables were also assessed by a projective personality measure (Rorschach). We found minimal differences in emotional adjustment between liver transplant and diabetic groups; on self-report measures, the adjustment of those with liver transplants was as good as, or better than, that of normative samples. However, on other tests, children with transplants differed from normative samples. On projective measures, liver transplant recipients had an increased number of depressive experiences, situationally related internal distress, and a greater tendency toward negative self-focus and evaluation. We conclude that in pediatric liver transplant recipients, behavioral and emotional adjustment is as good as in children with another chronic illness; in comparison with physically well children, the transplant recipients have subtle signs of emotional difficulties.

Adaptation, Psychological↗
PubMed1991

Computed tomography in the pre-operative assessment of mediastinal tumours--does it improve surgical management?

Computed tomography (CT) provides detailed imaging of the mediastinum. To assess whether this information improves subsequent surgical management 39 consecutive cases were reviewed. 21 patients had pre-operative CT of the mediastinum (CT group); 18 did not (No-CT group). The pre-operative use of CT resulted in the correct assessment of tumour consistency in 20 patients, the correct extent of invasion in 16, and the correct diagnosis in 10. In 15 of the 39 cases the surgical management was inappropriate because exploration was performed for an inoperable tumour, where no tumour was found, or when nonsurgical treatment was indicated. The number of inappropriate procedures was significantly lower in the CT group. These results suggest that the routine use of CT in the assessment of mediastinal tumours is justified by a subsequent improvement in surgical management.

Adult↗
PubMed1991

Neuropsychological outcome of pediatric liver transplantation.

Children with end-stage liver disease who undergo liver transplantation may have unrecognized neuropsychological and academic deficits, for which remediation programs may be available. Intellectual, academic, and neuropsychological measures of 28 pediatric patients who had received successful liver transplantation at least 1 year previously were compared with those of 18 patients with cystic fibrosis (to control for effects of growth retardation and chronic illness) matched for age, age at diagnosis, physical growth, and parents' socioeconomic status. Liver transplant patients had significantly lower scores on nonverbal intelligence tests (mean +/- SD for liver transplant vs cystic fibrosis patients: 89.1 +/- 19.1 vs 105.8 +/- 17.6), lower academic achievement, and lower zeta scores for age in the areas of learning and memory (-0.68 +/- 1.09 vs 0.19 +/- 1.24), abstraction and concept formation (-1.73 +/- 1.58 vs -0.79 +/- 1.37), visual-spatial function (-0.66 +/- 1.09 vs 0.10 +/- 0.69), and motor function (-0.13 +/- 0.85 vs 0.36 +/- 0.57). No differences were found on tests of verbal intelligence, or in alertness and concentration, perceptual-motor, and sensory-perceptual areas. Cyclosporine levels were found to correlate positively with motor speed (r = .41, P less than .05). Thorough psycho-educational and neuropsychological evaluations should be considered for pediatric patients who receive liver transplantation to allow these children to maximize their potential.

Adolescent↗
PubMed1990

Refinement of a partially oxygenated T state human haemoglobin at 1.5 A resolution.

The degree of ligation of T state human haemoglobin crystals is reduced by inositol hexaphosphate (IHP). The structure of a partially ligated haemoglobin has been refined using fast Fourier restrained-least-squares techniques. Manual interventions were required to escape from local minima and introduce a large number of solvent molecules. Individual isotropic temperature factors were refined for all atoms and the final average atomic temperature factor is 32.3 A2. The final R factor is 19.6% for all data between 10 and 1.5 A. The final model consists of 4560 protein atoms and 313 solvent molecules. The occupancies of the ligand atoms and the anisotropic behaviour of the iron atoms have been refined, demonstrating that the alpha haem groups are only partially ligated and that there is no ligation of the beta haems. Density for the IHP indicates that it is not well ordered even though changes in the ligation and structure of the haemoglobin indicate its presence.

Fourier Analysis↗
PubMed1990

Crystallization of the rainbow trout (Salmo gairdneri) haemoglobin IV.

Crystals of rainbow trout (Salmo gairdneri) haemoglobin IV were grown in mini batches from a solution of ammonium sulphate. Large single crystals grew over five days and were up to 2 mm in length. X-ray diffraction experiments indicated a space group of C222(1) with unit cell dimensions of a = 85.3 A, b = 94.6 A and c = 105.7 A. The crystals diffract to better than 2.5 A but exhibit some mosaicity along the c axis.

Animals↗
PubMed1990

Primary bone tumours of the thoracic skeleton: an audit of the Leeds regional bone tumour registry.

An audit of the Leeds regional bone tumour registry found that primary bone tumours of the thoracic skeleton constituted 90 of the 2004 cases (4.5%). Thirty seven per cent occurred in the ribs, 32% in the scapulae, 11% in the thoracic vertebrae, 11% in the sternum, and 9% in the clavicles. Malignant tumours were more common than benign (54 v 36) and occurred in an older population (mean ages 47 and 31 years). The scapula was the most common site for malignant lesions and the ribs the most common site for benign tumours. Chondrosarcoma was the commonest tumour in older patients, fibrous dysplasia and plasmacytoma in the middle age group, and eosinophilic granuloma in children. Presenting symptoms were a poor guide to whether the lesion was malignant or not. This and the small proportion of correct preoperative diagnoses indicate the need for early biopsy. Bone tumour registries provide a valuable source of cumulative information about uncommon tumours and facilitate accurate diagnosis, teaching, and research.

Adolescent↗