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Biomedical subjects

G Webb

Publications and source records attributed to G Webb.

At least 55 records · Page 3Linked to original sources
PubMed1997

The value of the MACE (Malone antegrade colonic enema) procedure in adult patients.

BACKGROUND: We report our experience with the Malone antegrade colonic enema (MACE) procedure in adult patients suffering from urinary incontinence and intractable constipation with or without fecal soiling. STUDY DESIGN: Since June 1990, the MACE procedure was initiated in 4 female and 12 male patients 14-54 years old (mean age, 29.9 years) with different pathologic conditions (myelodysplasia, n = 7; anorectal anomaly, n = 3; spinal cord lesion, n = 4; neuropathic disease of unclear cause, n = 2). Three surgical techniques were used: reversed and in situ appendix and tapered ileum). Complex simultaneous urologic continence procedures were performed in nine patients. Two patients had undergone previous operations in the lower urinary tract. RESULTS: After 6.6 years of followup (average, 41.7 months), eight patients (50%) were still using the MACE successfully. They were completely clean day and night and were relieved of symptoms of constipation. Eleven complications related to the MACE procedure occurred in seven patients (44%). Eight patients abandoned the procedure for various reasons. The failure rate was higher in chronically constipated patients without fecal soiling. CONCLUSIONS: The MACE procedure is associated with a high failure rate when used in adults, but it may be possible to identify a subgroup of patients in whom the procedure could be beneficial. Success would depend on overcoming technical problems and difficulties with patient compliance.

Adolescent↗
PubMed1996

Geometric mismatch of the aortic and pulmonary roots causes aortic insufficiency after the Ross procedure.

BACKGROUND: Geometric mismatch between the two semilunar valves can cause aortic insufficiency after the Ross procedure. Thus, whenever the aortic root is larger than the pulmonary root, surgical reduction of the aortic anulus or of the sinotubular junction (or both) to match the diameters of the pulmonary root is necessary to prevent late malfunction of the pulmonary autograft. METHODS: The Ross procedure was performed in 81 patients during the past 5 years. The diameters of the aortic and pulmonary roots were measured in 77 patients. Reduction of the aortic anulus and of the sinotubular junction was necessary in 27 patients, reduction of the aortic anulus alone in 12, and reduction of the sinotubular junction alone in 10. The pulmonary autograft was implanted in the subcoronary position in the aortic root in two patients, as a complete root replacement in 58, and as an inclusion root in 21. RESULTS: There was one operative death, caused by myocardial infarction. Aortic insufficiency developed in one patient who did not have measurement and reduction of the aortic anulus, and aortic root replacement was necessary 2 weeks later. Patients have been followed up from 2 to 64 months (mean 15 months). Two patients have required late reoperations: one because of pulmonary artery stenosis and the other because of a false aneurysm between the autograft and the mitral valve. The most recent Doppler echocardiographic study shows that 90% of the patients have only trace or no aortic insufficiency, and 10% have mild aortic insufficiency. CONCLUSION: This experience suggests that adjustment of the diameter of the aortic anulus or of the sinotubular junction of the aorta may be important to prevent aortic insufficiency after the Ross procedure.

Adolescent↗
PubMed1996

Report of the American Diabetes Association's Task Force on standardization of the insulin assay.

Recent large-scale epidemiological studies demonstrate that blood concentrations of immunoreactive insulin predict the development of NIDDM and IDDM and are associated with the risk of several degenerative diseases, such as coronary and peripheral vessel atherosclerosis, hypertension, and dyslipidemia. The reliability of these measurements is dependent on a biological assay that has not been well standardized between laboratories. Recognizing this, the American Diabetes Association organized a task force to assess comparability of blood insulin measurements between laboratories and to suggest techniques to improve comparability. The task force found that identical serum and plasma samples measured in different laboratories produced widely disparate values that were unacceptable for population comparisons. Use of a single reference standard did little to improve comparability. Assay characteristics such as linearity, recovery, accuracy, and cross-reactivity to proinsulin and its primary conversion intermediates varied among the laboratories, and they did not readily explain differences in the measurements made from assay to assay. Use of the same assay kit in different laboratories did not always ensure comparable measurements. Linear regression of assay results from one laboratory to an arbitrarily chosen reference assay greatly improved comparability and demonstrated the potential value in comparing each assay to a reference method. The task force report defines acceptable assay characteristics and proposes a three-step process of insulin assay proficiency and comparability. A central reference assay and ongoing sample exchange will be needed to allow reliable comparisons of insulin measurements made in different laboratories. Rigorous quality control and continuous quality improvement are needed to maintain reliability of the insulin measurement.

Diabetes Mellitus↗
PubMed1996

Referral of young adult patients with congenital heart disease to adult centres. The Canadian Adult Congenital Heart Network.

OBJECTIVE: To establish a process of referral for young adult patients with congenital heart disease from pediatric to adult centres. DESIGN: Directors of pediatric cardiology units across Canada were asked to complete a questionnaire detailing their process of referral of young adult patients with congenital heart disease to adult centres. They were also asked to respond to specific case scenarios. Adult cardiologist members of the Canadian Adult Congenital Heart Network were asked to respond to the same case scenarios. MAIN RESULTS: Most pediatric cardiology centres refer patients to adult cardiologists at 18 years of age. The process of referral generally involves a referral letter and relevant parts of the chart. Few centres arrange a booked appointment with the adult cardiologist, although this would be preferred by the majority of the responding adult cardiologists. Generally good agreement existed between pediatric and adult cardiologists with regard to the kind of patients who required specialized care at an adult congenital heart centre. CONCLUSION: Within Canada, a process is rapidly evolving to facilitate the transfer of care of young adults with congenital heart disease.

Adolescent↗
PubMed1996

Delayed diagnosis of acute rheumatic fever in adults: a forgotten cause of febrile polyarthritis.

Acute rheumatic fever is a nonsuppurative sequela of upper respiratory tract infection with group A streptococci. We describe our recent experience with the diagnosis and management of 3 cases of acute rheumatic fever to highlight the delays that may arise in the diagnosis of this condition. In adults, febrile polyarthritis is the most common presentation of acute rheumatic fever. Increased awareness on the part of the physician is necessary to ensure both prompt and accurate diagnosis of this cause of febrile polyarthritis.

Adult↗
PubMed1993

Evidence for clonal anergy as a mechanism responsible for the maintenance of transplantation tolerance.

The main stimulus triggering early acute allograft rejection is known to be delivered by the allogeneic "passenger" leukocytes present within the grafts. Once these cells have been replaced by cells of recipient origin, subsequent rejection episodes are generally less frequent and less acutely destructive. How this replacement affects the cell populations responsible for allograft rejection is not known. Here we report that rat alloreactive non-cytotoxic AS (RT1I) anti-August (RT1c) CD4+ T cells, that were shown to be specific for RT1.Bc+ August spleen stimulators, were able to cause acute rejection of normal August kidney allografts transplanted into sublethally irradiated AS recipients. These cells, however, failed to reject passenger cell-depleted (PCD) August kidneys, despite the substantial expression of RT1.Bc+ products on the graft tubular epithelium. In experiments in vitro, August kidney tubular epithelial cells expressing RT1.Bc+ antigens were found to be unable to stimulate the alloreactive T cells to proliferate. Moreover, preincubation with class II-positive August kidney epithelial cells specifically abrogated the alloreactivity of the T cells. Adding recombinant interleukin-2, however, restored the response to alloantigens. These results are consistent with the hypothesis that T cell populations capable of mediating early acute allograft rejection are different from those mediating late rejection, when donor passenger leukocytes are no longer present. They also suggest clonal anergy as one of the mechanisms responsible for maintaining long-term transplantation tolerance.

Animals↗
PubMed1993

Mediation of acute but not chronic rejection of MHC-incompatible rat kidney grafts by alloreactive CD4 T cells activated by the direct pathway of sensitization.

It has been previously postulated that there are two pathways of sensitization of MHC-incompatible kidney allografts: a direct pathway in which the host responder T cells are activated by MHC-incompatible passenger dendritic cells of the graft, and an indirect pathway, in which graft alloantigens are processed like "nominal" T cell antigens by host accessory cells, and presented as self-MHC restricted moieties. We show here that a rat AS anti-August alloreactive CD4+ T cell line, and a presumptive clone, activated through the direct pathway are capable in an adoptive transfer model of initiating rejection of normal August kidney grafts. However, neither the T cell line nor the presumptive clone initiates rejection of passenger cell-depleted August kidneys. The results support the hypothesis that direct pathway--sensitized T cells play a dominant role in early acute rejection, but not in chronic rejection.

Acute Disease↗
PubMed1992

Hepatitis B and delta virus infection among "at risk" populations in south east London.

STUDY OBJECTIVE: The hepatitis delta virus (HDV) contributes significantly to the morbidity and mortality of hepatitis B virus (HBV) infection, which is particularly prevalent among intravenous drug users and male homosexuals. A recent report has indicated that HDV first appeared in the South East London intravenous drug using population in 1982. The aim of the present study was to assess the prevalence of HDV in these two groups at risk of HBV infection in South East London. DESIGN: The study was a cohort analysis of HBV and delta virus serum markers, stratified temporally and with respect to intravenous drug use and sexual practice. SETTING: This was a population study of 372 consecutive intravenous drug users attending a local drug rehabilitation centre and 1481 subjects seen at a sexually transmitted disease clinic in the same area, during the years 1979 to 1988. MEASUREMENTS AND MAIN RESULTS: Of 372 intravenous drug users, 195 (52.4%) had evidence of current or past infection with HBV, of whom 17 had chronic HBV infection--a carriage rate of 8.7%. Twelve (70.6%) of these 17 also had chronic HDV infection--the first cases being identified in 1984. By comparison, 406 (27.4%) of the sexually transmitted disease clinic patients had been been exposed to HBV, 32 having chronic HBV: a carriage rate of 7.9% (7.5% v 9.4% among male homosexuals v male heterosexuals). Ten had been exposed to HDV (the first case in 1980) but only two (who did not admit to intravenous drug use) had chronic HDV infections (p less than 0.0005 v the rehabilitation centre patients). CONCLUSIONS: Although the HBV carriage rate is very similar in these two populations, chronic HDV infections were mainly confined to intravenous drug users. However, reports from the USA and France indicate spread of delta virus to the male homosexual community and, since there is clearly a pool of HDV in SE London, vaccination against HBV in these risk groups in likely to be cost-effective and should be actively encouraged.

Female↗
PubMed1992

Fatal esophageal-arterial fistula 17 years following tetralogy of Fallot repair.

Blalock-Taussig shunts (subclavian to pulmonary anastomoses) have remained the most effective palliation in cyanotic heart disease. Late complications are rare but can be devastating. The case of a 26-year-old female with tetralogy and an original Blalock shunt constructed at age four years is reported. Despite subsequent primary repair of the tetralogy and presumed ligation of the Blalock shunt, the patient succumbed to a fatal hemorrhage due to esophageal-arterial fistula involving the Blalock shunt. The circumstances leading to this dramatic outcome are outlined and discussed. It is important for cardiologists caring for congenital heart disease patients to be aware of the late complications of congenital heart surgery, and carry out the proper follow-up investigations.

Adult↗
PubMed1991

Qualitative methods in operations research on contraceptive distribution systems: a case study from Nigeria.

This article discusses the application of qualitative methods in operations research on a family planning service delivery system. Market traders in Ibadan, Nigeria were trained to sell oral contraceptives, condoms, and spermicidal foaming tablets in a collaborative research project of the Fertility Research Unit of the University College Hospital, Ibadan, and the Center for Population and Family Health of Columbia University. Focus group discussion, participant observation, and semi-structured interviews were used to investigate the cultural acceptability of distribution of contraceptives in the market places and the motivations of participating traders. The strength of the market associations was a factor influencing acceptance of the project and the number of customers for the traders' other wares were found to positively influence the volume of sales of contraceptives. Traders were motivated by the status associated with participating in a program of a well-known health institution. Findings from qualitative research suggest areas for quantitative studies and vice versa in an interactive process.

Attitude to Health↗
PubMed1991

Entrapping of the clotted intra-aortic balloon in the descending aorta.

Percutaneous insertion of a catheter for intra-aortic balloon pumping (IABP) was introduced in 1979 by Bregman and Casarella and has become a popular technique. Rupture of the balloon, allowing clot to form inside it, is rare. When the clot is large, it may cause entrapping of the balloon. This is a potentially dangerous complication of IABP. We are aware of only one case report of this complication, by Aru and co-workers. The entrapping of the balloon in their report occurred at the site of insertion in the femoral artery. We report here a case in which the entrapping occurred in the descending aorta, and its removal required extensive exposure of the aortic bifurcation.

Aged↗
PubMed1991

Delayed haemolytic transfusion reactions in patients with sickle cell disease.

We describe two cases which illustrate the difficult diagnostic and therapeutic problems posed by delayed haemolytic transfusion reactions in patients with sickle-cell disease. The cases emphasize the need for meticulous phenotypic and serological assessment of sickle-cell patients prior to transfusion therapy.

Adolescent↗