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Biomedical subjects

W Williams

Publications and source records attributed to W Williams.

At least 19 recordsLinked to original sources
PubMed2006

Prenatal detection of heart defects in a non-selected population of 30,149 fetuses--detection rates and outcome.

OBJECTIVES: To evaluate the detection rate of congenital heart defects (CHD) in a non-selected population and to follow outcome after diagnosis. METHODS: All 30,149 fetuses/newborns that were scheduled to deliver at our hospital between February 1991 and December 2001 were registered prospectively. Of these, 29,460 (98%) fetuses had a prenatal ultrasound scan at our center. The routine fetal examination at approximately 18 weeks' gestation included the four-chamber view and the great arteries of the fetal heart. The follow-up period was 2-13 years. RESULTS: Of 97 major CHDs, 55 (57%) were detected prenatally, 16% (9/55) prior to, 66% (36/55) at and 18% (10/55) after the routine scan. Forty-four percent (19/43) of the isolated CHDs, 67% (36/54) of those with associated malformations and 48% (11/23) of the isolated ductal-dependent CHDs were detected. Thirty-eight percent (37/97) had an abnormal karyotype. Of the 55 major CHDs detected, 44% (24) of the pregnancies with lethal/serious fetal malformations were terminated, 15% (8) died in utero, 42% (23) were born alive and 27% (15) were still alive after 2 years. Of the 42 CHDs detected postnatally, 2% (1) were terminated for other reasons, 98% (41) were born alive and 81% (34) were still alive after 2 years. CONCLUSIONS: Prenatal detection of CHD is still a challenge, with a 57% detection rate only. Isolated defects are detected less frequently. The overall outcome suggests that the most severe defects are detected with the present screening setting; only 27% of the babies with major CHDs detected were still alive after 2 years. Data from long-term follow-up will be of importance for the counseling process.

Adolescent↗
PubMed2006

Factors affecting farm noise during common agricultural activities.

Hearing injury due to exposure to excessive noise during common farming activities is a significant problem for farmers. The aim of this study was to investigate factors that affect the level of risk to hearing caused by common farming activities. Noise levels on farms were measured across a range of activities and producer groups, and situational factors that effect noise levels were also investigated. Older tractors were found to be 6 dB louder than newer tractors. Cabs reduced noise to the operator by 16 dB, which was halved to 8 dB if a door was open. Radios added between 3 and 5 dB to the noise in the cab. These variables significantly affect the noise level at the ear of operators and others in the workplace, and affect the subsequent exposure limits that are considered safe. Situational factors need to be considered in assessing the level of risk to farmers' hearing and in choosing noise management strategies on the farm. This information has been incorporated into material about hearing and discussions with farmers who participated in field day hearing screening programs in Australia.

Agricultural Workers' Diseases↗
PubMed2005

Implantation of endovascular stents for the obstructive right ventricular outflow tract.

OBJECTIVES: To evaluate the effectiveness and long term outcomes of catheter intervention for obstructive conduits between the right ventricle and pulmonary arteries. DESIGN: Retrospective chart review. SETTING: Tertiary care paediatric cardiology unit. PATIENTS AND INTERVENTIONS: 70 procedures in 68 children (median age at intervention 6 years, median interval after conduit insertion 3.4 years) were analysed. All children had haemodynamic indications for conduit replacement. Twenty four children underwent a second intervention (stent dilatation in 17, second stent implantation in seven). RESULTS: Mean (SD) conduit pressure gradient decreased from 44 (18) mm Hg to 18 (12) mm Hg at the initial intervention (n = 62, p < 0.001) and from 39 (15) mm Hg to 23 (10) mm Hg at the second intervention (n = 16, p < 0.001). The percentage of the predicted right ventricular outflow area increased from 17 (9)% to 44 (22)% at the initial intervention (n = 62, p < 0.001) and from 24 (8)% to 29 (11)% at the second intervention (n = 21, p < 0.001). The conduit was subsequently replaced in 33 children. Freedom from conduit replacement from the time of stent implantation was 83%, 75%, and 47% at one, two, and five years, respectively, and from the time of the initial conduit surgery it was 87%, 64%, and 42% at five, eight, and 10 years, respectively. Body growth was maintained, no deaths were reported during follow up, and pulmonary insufficiency was well tolerated. CONCLUSION: A catheter treatment strategy for obstructive conduits is safe and effective in prolonging conduit function.

Adolescent↗
PubMed2005

Farm noise emissions during common agricultural activities.

Noise injury in agriculture is a significant yet often unrecognized problem. Many farmers, farm workers, and family members are exposed to noise levels above recommended levels and have greater hearing loss than their non-farming contemporaries. The aim of this study was to gather up-to-date information on farm noise levels and to enhance the quality of information available to assist farmers in reducing noise exposure and meeting Occupational Health and Safety (OHS) regulations regarding noise management. Farm visits were conducted on 48 agricultural establishments that produce a range of commodities. Noise levels were measured at the ears of operators and bystanders involved in typical activities on farms. The average and peak noise levels were measured for 56 types of machinery or sites of farming activity, totaling 298 separate items and activities. Common noise hazards identified included firearms, tractors without cabs, workshop tools, small motors (e.g., chainsaws, augers, pumps), manual handling of pigs, shearing sheds, older cabbed tractors, and heavy machinery such as harvesters, bulldozers, and cotton module presses. We found that use of firearms without hearing protection presents a pressing hearing health priority. However, farming activities involving machinery used for prolonged periods also present significant risks to farmers' hearing health. Noise management strategies on the farm are essential in order to prevent noise injury among farmers.

Agricultural Workers' Diseases↗
PubMed2005

Modeling cancer registration processes with an enhanced activity diagram.

OBJECTIVES: Adequate instruments are needed to reflect the complexity of routine cancer registry operations properly in a business model. The activity diagram is a key instrument of the Unified Modeling Language (UML) for the modeling of business processes. The authors aim to improve descriptions of processes in cancer registration, as well as in other public health domains, through the enhancements of an activity diagram notation within the standard semantics of UML. METHODS: The authors introduced the practical approach to enhance a conventional UML activity diagram, complementing it with the following business process concepts: timeline, duration for individual activities, responsibilities for individual activities within swimlanes, and descriptive text. RESULTS: The authors used an enhanced activity diagram for modeling surveillance processes in the cancer registration domain. Specific example illustrates the use of an enhanced activity diagram to visualize a process of linking cancer registry records with external mortality files. CONCLUSIONS: Enhanced activity diagram allows for the addition of more business concepts to a single diagram and can improve descriptions of processes in cancer registration, as well as in other domains. Additional features of an enhanced activity diagram allow to advance the visualization of cancer registration processes. That, in turn, promotes the clarification of issues related to the process timeline, responsibilities for particular operations, and collaborations among process participants. Our first experiences in a cancer registry best practices development workshop setting support the usefulness of such an approach.

Computer Simulation↗
PubMed2005

Sustainable management of leakage from wastewater pipelines.

Wastewater pipeline leakage is an emerging concern in Europe, especially with regards to the potential effect of leaking effluent on groundwater contamination and the effects infiltration has on the management of sewer reticulation systems. This paper describes efforts by Australia, in association with several European partners, towards the development of decision support tools to prioritize proactive rehabilitation of wastewater pipe networks to account for leakage. In the fundamental models for the decision support system, leakage is viewed as a function of pipeline system deterioration. The models rely on soil type identification across the service area to determine the aggressiveness of the pipe environment and for division of the area into zones based on pipe properties and operational conditions. By understanding the interaction between pipe materials, operating conditions, and the pipe environment in the mechanisms leading to pipe deterioration, the models allow the prediction of leakage rates in different zones across a network. The decision support system utilizes these models to predict the condition of pipes in individual zones, and to optimize the utilization of rehabilitation resources by targeting the areas with the highest leakage rates.

Decision Making↗
PubMed2004

Role of breathers in anomalous decay.

We have previously presented evidence for the formation of breathers in doped alkali halides subjected to a flash of UV light. Properties of these breathers, their phase space structure, robustness, decay, and propensity for formation, are studied here. Under a wide range of parameters and interionic potentials they form two-dimensional Kolmogorov-Arnold-Moser tori (less than generic) in phase space. Strobed views of these tori, useful in quantization, are shown. All features support the thesis of breather formation as the explanation for the luminescence decay anomaly that first motivated our breather proposal.

Journal Article↗
PubMed2003

Severity of systemic lupus erythematosus with diffuse proliferative glomerulonephritis and the ineffectiveness of standard pulse intravenous cyclophosphamide therapy in Jamaican patients.

The majority of patients seen at the renal clinic of the University Hospital of the West Indies (UHWI) are of African descent. The case notes of patients with systemic lupus erythematosus (SLE) with class 4 nephritis and who were given standard pulse intravenous cyclophosphamide therapy during the period 1990-2000 were retrospectively reviewed. Primary outcomes were doubling of serum creatinine and development of end stage renal disease (ESRD). Secondary outcomes were return of proteinuria to normal and renal remission. A total of 117 patients had a renal biopsy for SLE nephritis at the UHWI between 1990 and 2000. Of the patients, 34 (29%) had diffuse proliferative glomerulonephritis (WHO class 4), of which 29 were reviewed. Twenty-two patients of 24 in whom it was measured (92%) had significant proteinuria at presentation. The 24-hour proteinuria was measured at final review in 16 patients and in 10 patients it went into complete remission. At the beginning of therapy, 24 patients (83%) had renal impairment. Of the 18 who had final creatinine values, the renal function returned to normal in eight patients (44%) and an additional six patients showed a significant improvement in renal function at final review. Six patients developed end stage renal disease (ESRD). The risk (95% confidence interval) of developing ESRD at one year was 16.2% (CI, 6.4-37.6) and at two years was 23.2% (CI, 10.0-48.5). There were three deaths, two from sepsis and one from heart failure. The one-year mortality (95% CI) was 8% (CI, 2.0-28.5), the two-year mortality was 15.6% (CI, 4.9-43.5) and the five-year mortality was also 15.6% (CI, 4.9-43.5). Intravenous pulse cyclophosphamide for Jamaican patients with SLE and diffuse proliferative glomerulonephritis is an ineffective form of treatment.

Adolescent↗
PubMed2001

N-alkyl substituted analogs of the sigma receptor ligand BD1008 and traditional sigma receptor ligands affect cocaine-induced convulsions and lethality in mice.

Cocaine binds to sigma receptors with comparable affinity to its well-established interaction with dopamine transporters. Previous studies have shown BD1008 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine) to have high affinity and selectivity for sigma receptors, and to additionally attenuate the locomotor stimulatory effects of cocaine. Therefore, in the present study, three N-alkyl substituted analogs of BD1008 were characterized in receptor binding and behavioral studies: BD1060 (N-[2-(3,4-dichlorophenyl)ethyl]-2-(1-pyrrolidinyl)ethylamine), BD1067 (N-[2-(3,4-dichlorophenyl)ethyl]-N-ethyl-2-(1-pyrrolidinyl)ethylamine), and BD1052 (N-[2-(3,4-dichlorophenyl)ethyl]-N-allyl-2-(1-pyrrolidinyl)ethylamine). Similarly to BD1008, all three analogs exhibited high affinity and selectivity for sigma receptors. In behavioral studies, BD1008, BD1060 or BD1067 attenuated cocaine-induced convulsions and lethality in Swiss Webster mice. The protective effects appear to be mediated through sigma receptor antagonism because traditional sigma receptor antagonists with high to moderate affinity for these receptors also attenuated the behavioral toxicity of cocaine. In contrast, traditional and novel sigma receptor agonists such as di-o-tolylguanidine and BD1052 worsened the behavioral toxicity of cocaine. To further characterize the actions of the N-alkyl substituted compounds, they were microinjected into the rat red nucleus, a functional assay of sigma receptor activity, where they produced agonist vs. antagonist actions that were consistent with their effects on cocaine-induced behaviors. Together, the data demonstrate that BD1008, BD1060 or BD1067 can attenuate the behavioral toxicity of cocaine, most likely through functional antagonism of sigma receptors.

Alkylation↗
PubMed2001

Lung function and aerobic capacity in adult patients following modified Fontan procedure.

OBJECTIVE: To examine cardiopulmonary performance in 52 adult patients with a Fontan circulation. DESIGN: Retrospective cohort study. Values of maximum oxygen uptake (VO(2)max), maximum heart rate (HRmax), forced vital capacity (FVC), and forced expiratory volume in one second (FEV(1)) were compared with predictive values for different age groups. Patients were further subdivided into those with a pulmonary artery connection (RA-PA) or right atrium to right ventricle conduit (RA-RV). RESULTS: At late follow up (median 10 years, range 1 to 26 years), patients with Fontan circulation had greatly diminished VO(2)max, HRmax, FVC, and FEV(1) compared with predicted values. Early age at surgery had a positive impact on aerobic capacity. The FEV(1):FVC ratio indicated restrictive lung function. No differences were found with respect to any variable between patients with RA-PA connections and those with RA-RV connections. CONCLUSIONS: Patients with a Fontan circulation have greatly diminished values of aerobic capacity and a restrictive pattern of lung function. Patients with an early surgical procedure obtained higher values of VO(2)max. The theoretical benefits of including the right ventricle in a Fontan circulation were not apparent.

Adult↗
PubMed2001

Correlation of cerebrovascular reserve as measured by acetazolamide-challenged SPECT with angiographic flow patterns and intra- or extracranial arterial stenosis.

BACKGROUND AND PURPOSE: The ability to identify patients at increased risk for stroke from cerebral hemodynamic ischemia may help guide treatment planning. We tested the correlation between regional cerebrovascular reserve (rCVR) on acetazolamide-challenged single-photon emission CT (SPECT) brain scans and intracranial collateral pathways as well as extra- or intracranial (EC-IC) arterial stenosis on cerebral angiography. METHODS: A retrospective analysis of 27 patients who underwent cerebral angiography and acetazolamide-challenged SPECT brain imaging was performed. With cerebral angiography, the anterior, middle, and posterior cerebral artery (ACA, MCA, PCA) territories were evaluated for patterns of flow, including the ipsilateral carotid or basilar arteries, the circle of Willis collaterals, the EC-IC collaterals, and the leptomeningeal collaterals. With acetazolamide-challenged SPECT, the ACA, MCA, and PCA territories were classified as either showing or not showing evidence of decreased rCVR. Statistical significance was determined by the chi(2) test. RESULTS: Patients with decreased rCVR had significantly greater dependence on either the EC-IC or leptomeningeal collaterals (42%) than did patients without decreased rCVR (7%). Similarly, the cerebral hemispheres with decreased rCVR showed a higher prevalence of 70% or greater stenosis or occlusion of the ipsilateral EC-IC arteries in the anterior circulation (74%) than did hemispheres with no evidence of decreased rCVR (16%), and this difference was also statistically significant. CONCLUSION: Acetazolamide-challenged SPECT brain scanning provides additional information regarding rCVR that is not reliably provided by cerebral angiography.

Acetazolamide↗
PubMed2001

The kidney transplant program at the Massachusetts general hospital.

Between February 1963 and December 2000, 1,627 kidney transplants were performed at the Massachusetts General Hospital. The majority (62%) were from cadaveric donors, although in recent years (1996-2000) 52% have been allografts from living donors, with an increase in living unrelated donors. The introduction of CsA and OKT3 in 1984 was associated with a significant improvement in actuarial renal allograft survival, although a persistent late attrition of allografts continues beyond the first year after transplantation. As reported in other centers, current actuarial survival for living unrelated allografts is superior to that of cadaveric allografts, and is quite similar to that observed in recipients of non-HLA identical living-related transplants. Our preliminary laparoscopic donor nephrectomy experience is encouraging as excellent allograft survival and function has been observed, with minimal morbidity associated with the procedure and a low rate of conversion to open nephrectomy. Recent changes in immunosuppressive protocols have resulted in lower early acute rejection rates, however the incidence of delayed graft function remains unchanged in cadaveric renal transplantation. The role of humoral immunity in allograft rejection has been progressively clarified and new approaches to control donor specific alloantibody production have been shown to be effective. Current clinical studies are ongoing to determine the optimal type and dose of calcineurin inhibitors beyond the first year after transplantation and to study whether avoidance of steroids is safe and feasible. Finally, an innovative tolerance induction protocol using the mixed chimerism approach has been successfully accomplished in selected patients with end-stage renal disease secondary to multiple myeloma. These encouraging observations emphasize that major changes from current immunosuppressive regimens are likely to occur over the next few years as more approaches to tolerance induction are explored clinically.

Graft Rejection↗