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Biomedical subjects

J Williams

Publications and source records attributed to J Williams.

At least 541 records · Page 30Linked to original sources
PubMed1995

[Ultrasonography in veterinary ophthalmology].

Ophthalmic examination evaluates ocular structures in both the anterior and the posterior segments of the eye. In the eye without opacities of the transmitting media, this is accomplished through biomicroscopy, direct and indirect ophthalmoscopy. However, in eyes with media opacities, evaluation, especially of the posterior segment, is difficult or impossible by these routine methods. Further, evaluation of retrobulbar tissues has been limited to radiography and blind aspirate, or surgical exploration. Ultrasound is a noninvasive, safe procedure that allows evaluation of the intraocular and retrobulbar tissues without sedation or general anesthesia.

Animals↗
PubMed1995

Recruitment and retention of subjects for a longitudinal cancer prevention study in an inner-city black community.

Recruiting and retaining subjects for longitudinal prevention trials is challenging. The inherent difficulties are compounded when the trial is to take place in a low-income minority community, since prevention is a low priority among residents of such communities, and research is viewed with suspicion. We present our experiences in attempting to recruit and retain low-income black women living in inner-city Atlanta for a trial of an educational intervention to promote screening for cancer. The intervention was conducted in the home by trained lay health workers. We found that recruitment was more successful when we recruited directly from the community than when we recruited from the patient registry of a primary health care center. The attrition rate over an 18-month period was high. Among members of the intervention group, those retained in the study tended to be wealthier and better educated and were more likely to be married and employed than those who dropped out. It seems probable that women of lower socioeconomic status found our intervention to be intrusive or burdensome. Among the controls, socioeconomic factors did not discriminate between those who completed the study and those who did not; loss to follow-up in this group was associated only with younger age. In conducting research of this type in low-income minority communities, special attention must be given to issues of recruitment and retention if the validity of the study is to be preserved.

Adolescent↗
PubMed1995

A simple modification in operative technique can reduce the incidence of nonanastomotic biliary strictures after orthotopic liver transplantation.

Nonanastomotic strictures after liver transplantations are a source of significant morbidity, often necessitating retransplantation. The purpose of this study was twofold: first to identify features associated with the development of this lesion; second, to make technical modifications that will decrease the incidence of this problem. In the first part of this study, 15 of 131 patients were diagnosed with nonanastomotic biliary stricture. A stepwise logistic-regression analysis associated donor cold ischemic time and dopamine dose with the development of nonanastomotic biliary strictures. All these patients had arterial reconstruction after partial revascularization of the liver with portal venous blood. Because the bile duct receives its blood supply from only the hepatic artery, we hypothesized that the prolonged period of warm ischemia from staged reconstruction of the vascular supply would promote the development of this lesion. In a second part of this study, the stricture rate in 45 patients with simultaneous revascularization using both the hepatic artery and portal vein was compared with that in 83 patients from the first part of this study initially revascularized with portal venous blood. All patients in the second study had grafts preserved using UW solution. Only 1 patient with simultaneous revascularization developed a nonanastomotic biliary stricture. Because we were unable to identify any significant complications related to this method of revascularization, we propose that the hepatic artery and portal vein should be released simultaneously, especially in patients receiving a graft with prolonged storage time.

Adenosine↗
PubMed1995

Clinical implications of intra- and inter-reader agreement in four different automated visual fields.

BACKGROUND: This study was designed and conducted to examine the degree of inter- and intra-reader agreement when four readers evaluate visual fields in patients known to have glaucoma and patients known to not have glaucoma. METHODS: Fifty-three patients known to have glaucoma and 60 patients known not to have glaucoma were selected randomly from a population at the University of Alabama at Birmingham School of Optometry. Four visual fields were performed on each patient, non-dilated, with the proper correction in place. The fields were performed on three different instruments by technicians who were unaware of the diagnostic status of the patient. Four independent (blinded) clinicians read the visual fields and judged them as: "glaucoma field defect," "no glaucoma field defect," and "poor reliability-cannot judge." RESULTS: Statistical analysis revealed that a single reader's interpretation of four different types of visual fields are very different from, are poorer than, and are more consistent than are the four readers' interpretations of a single type of visual field. The analysis also shows that the readers consistently underestimated the number of glaucoma patients with one instrument and overestimated the number with another. CONCLUSIONS: This results suggest that a single visual field will discriminate patients with glaucoma with an accuracy in the 70 to 75 percent range. For one of the instruments, the shorter protocol was almost as effective in discriminating glaucomatous fields as the longer protocol. This study also suggests that repeating the visual fields or analysis of a single field by two readers improves reliability.

Aged↗
PubMed1994

Phenotypic definitions of psychotic illness for molecular genetic research.

New approaches to establish the molecular genetic bases of psychotic illness have recently been suggested which make different demands on diagnosticians attempting to provide reliable and valid phenotypic definitions. The diagnostic problems that have arisen to date and some solutions to these are considered. In addition, future diagnostic requirements for linkage and association studies are discussed.

Cognition↗
PubMed1994

Chorionic villi sampling: laboratory experience with 4,000 consecutive cases.

Experience with 4,000 consecutive CVS cases shows that 1) the combination of both the direct and culture methods greatly reduces false diagnoses and maternal cell contamination; 2) the time interval between the sampling procedure and processing of villus specimens influences the quality of direct preparations; 3) maternal cell contamination (MCC) can be minimized with dissection of CVS specimens. We have compiled a large volume of confined placental mosaicism (CPM) cases to serve as a resource in interpreting mosaic cytogenetic findings. It was noted that, in up to 92% of the mosaic cases, the abnormal cell line was confined to the placenta. The frequency of true chromosomal mosaicism was 0.2%, and is not different from that for amniocentesis.

Cells, Cultured↗
PubMed1994

Repeat length variation in the dopamine D4 receptor gene shows no evidence of association with schizophrenia.

The D4 receptor has been shown to exist in several allelic forms (Van Tol et al., Nature 358:149-152, 1992) reflecting variation in the number of 48 base-pair sequence repeats in the putative cytoplasmic loop. We report a comparison of repeat length variation between schizophrenic patients and controls. Our sample of 106 unrelated schizophrenic cases and 119 controls showed no significant differences in allele or genotype distribution between patients and controls. In particular, we were unable to support the previous observation of an excess of 4-repeat homozygotes in patients.

Alleles↗
PubMed1994

Interactions between the Escherichia coli MelR transcription activator protein and operator sequences at the melAB promoter.

The Escherichia coli MelR protein binds to two sites at the melAB promoter and activates transcription in response to melibiose. The binding of purified MelR to the melAB promoter and to a number of derivatives carrying point mutations has been studied. A melAB promoter fragment that is very weakly activated by the melR gene product has been made by creating multiple symmetrical changes in both MelR-binding sites. A library of random substitutions in MelR was screened to find mutants that were able to activate this mutant promoter. One of these mutants contained a substitution in a proposed helix-turn-helix region that most likely relaxes the sequence-specificity of MelR binding. The other mutants contain substitutions throughout the central part of MelR and appear to alter the conformation of MelR, such that activity is triggered at lower melibiose concentrations and by arabinose.

Base Sequence↗
PubMed1994

Patterns of cell movement within the Dictyostelium slug revealed by cell type-specific, surface labeling of living cells.

There are cells scattered in the rear, prespore region of the Dictyostelium slug that share many of the properties of the prestalk cells and that are therefore called anterior-like cells (ALCs). By placing the gene encoding a cell surface protein under the control of an ALC-specific promoter and immunologically labeling the living cells, we analyze the movement of ALCs within the slug. There is a posterior to anterior cellular flow, and the ALCs change their movement pattern as they enter the prestalk zone. Prestalk cells are periodically shed from the migrating slug. They must be replaced if the correct ratio of prestalk to prespore cells is to be maintained, and we present evidence for the transdifferentiation of prespore into prestalk cells, with ALCs functioning as intermediates in the transition. The slug has, therefore, a surprisingly dynamic structure, both with respect to cellular differentiation and cell movement.

Amino Acid Sequence↗
PubMed1994

Relationship between homozygosity at the dopamine D3 receptor gene and schizophrenia.

We have reported an association between schizophrenia and homozygosity of a Bal I polymorphism in the first exon of the dopamine D3 receptor gene (Crocq et al.: Journal of Medical Genetics 29:858-860, 1992). The present study consists of an attempt to replicate this finding in a further sample of 66 patients and 97 controls. Once again more patients than controls were homozygous, but the effect was not as strong as in our first study (chi 2 = 2.53, P = 0.05, one tailed). When pooled data from our two studies were analysed, excess homozygosity in patients remained highly significant (P = 0.002) with a particular excess of the 1:1 genotype (P = 0.01). This reflected a departure from Hardy-Weinberg equilibrium in the patients (P = 0.0005) but not the controls (P = 0.24). This led us to explore the possibility that there might be important differences between the patients in our two studies and that excess homozygosity might be a characteristic of particular subgroups of schizophrenics. Our findings suggest that the effect is consistently at its strongest in those patients who have a high familial loading and in those who have a good response to neuroleptic treatment, and that differences between our two samples might have contributed to the quantitatively different outcomes.

Adult↗
PubMed1994

Purchasing for all: an alternative to fundholding.

OBJECTIVE: To evaluate general practitioner participation in a district health authority's purchasing work. DESIGN: Questionnaire study of 131 Hackney general practitioners and 33 senior health service managers; review of the minutes of 28 meetings of the Hackney General Practitioners' Forum and the contract between City and Hackney Health Authority and the St Bartholomew's NHS Trust. SETTING: Hackney General Practitioners' Forum. MAIN OUTCOME MEASURES: General practitioners' and managers' perceptions of how representative and effective the general practitioners' forum is; proportion of new quality targets and service developments contributed by general practitioners; main issues discussed by the forum and impact on district health authority policy. RESULTS: 99 (76%) general practitioners and 27 (82%) managers responded. Both groups perceived the forum as representative. 92% (24/26) of the managers thought the forum was effective but only 74% (70/95) of general practitioners did so, largely because some doubted that the forum was listened to 75% (103/138) of quality targets and 55% (16/29) of service developments planned in the 1993-4 contract were contributed by general practitioners. They also lobbied successfully for more resources for urology and community mental health services. CONCLUSIONS: Input into commissioning via a general practitioners' forum can be both representative and effective. General practitioners need to work closely to achieve a consensus and those involved need administrative support. The relation between general practice and public health medicine needs to be strengthened.

Attitude of Health Personnel↗
PubMed1994

Investigation of thermoregulatory characteristics in patients with Prader-Willi syndrome.

A survey instrument is used to assess temperature regulation characteristics in children with Prader-Willi syndrome (PWS) compared to 3 control groups: sibs of PWS patients (SIB), neurodevelopmentally handicapped children (ND), and age and gender matched well children (WC). Significant differences were found between PWS patients, SIB controls, and WC controls in the prevalence of febrile convulsions, fever-associated symptoms, and temperature less than 94 degrees F. No differences were noted in any variable between the PWS patients and the ND controls, suggesting that these abnormalities are not unique to PWS, but can occur in any neurodevelopmentally handicapped individual, further suggesting these do not necessarily reflect syndrome-specific hypothalamic abnormalities.

Body Temperature Regulation↗
PubMed1994

Intravenous iloprost infusion in patients with Raynaud phenomenon secondary to systemic sclerosis. A multicenter, placebo-controlled, double-blind study.

OBJECTIVE: To evaluate the efficacy and safety of iloprost, a prostacyclin analog, administered intravenously in patients with Raynaud phenomenon secondary to systemic sclerosis. DESIGN: Multicenter, randomized, parallel placebo-controlled, double-blind study. SETTING: University medical centers. PATIENTS: 131 patients with systemic sclerosis (101 women, 30 men) ages 20 to 79 years. INTERVENTION: Patients were randomly assigned to receive one of two parallel treatments of five daily sequential, 6-hour intravenous infusions of iloprost (0.5 to 2.0 ng/kg per min) or to receive a similar volume of placebo. MEASUREMENTS: Frequency of Raynaud attacks, Raynaud severity score, physician's overall rating of treatment effect, and digital cutaneous lesion healing. RESULTS: Of the 131 patients enrolled, 126 completed the 5-day infusion and 114 (87%) completed at least 6 weeks of follow-up. Sixty-four patients were randomly assigned to receive iloprost and 67 patients, to receive placebo. The mean weekly number of Raynaud attacks decreased 39.1% with iloprost and 22.2% with placebo (P = 0.005). In addition, the mean percentage of improvement in a global Raynaud severity score during the entire 9-week follow-up was greater in patients given iloprost (34.8%) than in those receiving placebo (19.7%) (P = 0.011). The physician's overall rating of treatment effect showed greater improvement with iloprost than with placebo at week 6 (52.4% compared with 27.4%; P = 0.008) and week 9 (60.9% compared with 26.9%; P < 0.001). At week 3, 14.6% more patients receiving iloprost had 50% or more lesions heal compared with those given placebo (95% CI, 0.9% to 30%). During the infusion, 59 (92%) of the patients receiving iloprost had one or more side effects compared with 38 (57%) of the patients receiving placebo. CONCLUSION: Iloprost is effective for the short-term palliation of severe Raynaud phenomenon in patients with systemic sclerosis.

Adult↗
PubMed1994

Evaluation of the cost of laparoscopic and open cholecystectomy.

Despite the rapid growth of laparoscopic cholecystectomy, the comparative costs of this new procedure and open cholecystectomy remain unknown. In this study the costs have been evaluated of a consecutive series of patients undergoing these procedures in a district general hospital with an established resource management centre. Fifty consecutive patients undergoing open cholecystectomy between June 1988 and July 1990 immediately before the introduction of laparoscopic cholecystectomy and 100 patients undergoing laparoscopic cholecystectomy between August 1990 and June 1992 were studied. Costs estimated prospectively for each patient were compared. The mean cost per patient of open cholecystectomy was estimated at 2102 pounds compared with 2026 pounds for the first 50 patients undergoing the laparoscopic procedure. The mean cost (1744 pounds) for the second 50 patients undergoing laparoscopic cholecystectomy was less than that for either open cholecystectomy (P < 0.005) or the initial 50 laparoscopic operations (P < 0.03). Operating theatre costs and equipment costs were higher in both laparoscopic groups. These were offset by the higher nursing and ward costs of open cholecystectomy. For the laparoscopic procedure the operating theatre times and duration of hospital stay were both less in the second 50 patients than in the first 50. After the initial learning period, laparoscopic cholecystectomy is less expensive than the open operation and represents a cost-effective method for treatment of the patient with gallstones.

Adult↗