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Biomedical subjects

K T Woo

Publications and source records attributed to K T Woo.

At least 19 recordsLinked to original sources
PubMed1992

Cytomegalovirus infection in renal transplant patients with hepatitis B--case report.

Cytomegalovirus (CMV) infection in Hepatitis B carrier renal transplant patients who are immunosuppressed can be easily overlooked especially in those presenting with jaundice and liver failure. Recognising hepatitis due to CMV in renal transplant patients who are also hepatitis B carriers is important therapeutically as measures for the treatment and prevention of CMV infection are already available. This is especially so as Hepatitis B has a moderately high prevalence in this part of the world. We describe our clinical experience of cytomegalovirus infection in two renal transplant patients who are also asymptomatic hepatitis B carriers.

Adult↗
PubMed1992

Infection in continuous ambulatory peritoneal dialysis (CAPD): aetiology, complications and risk factors.

Continuous ambulatory peritoneal dialysis (CAPD) was started in the Singapore General Hospital in 1980. Peritonitis and exit site infections have been the major cause of morbidity and catheter loss in CAPD. In 1990, 130 patients were on CAPD and the peritonitis rate was one episode in 20.4 patient months. Gram positive organisms accounted for 54% of the infections of which Staphylococcus epidermidis was the commonest (24%). Catheter removal was required in 14% of the cases and 9% of the patients discontinued CAPD as a result of peritonitis. The exit site infection rate was one episode in 27.5 patient months and the commonest organism was Staphylococcus aureus (54%). Twenty-three (47%) of the cases of exit site infection required catheter removal and 83% of the cases were the result of S. aureus infections. Patients with preexisting exit site infections experienced more episodes of peritonitis. Patients above the age of 50 years experienced more episodes of peritonitis and exit site infection. Sex, diabetes and the duration on CAPD did not influence the frequency of infections. Patients using the UV Germicidal Exchange Device had fewer episodes of peritonitis than those using the conventional spike system.

Adolescent↗
PubMed1992

The impact of HLA match transfusions and presensitization on renal transplantation in the cyclosporine era.

The successful engraftment of a renal transplant is dependent on multiple factors, immunological factors being of major importance. Specifically, histocompatibility, lymphocytotoxic antibodies and pretransplant blood transfusions have been shown to play a major role in determining graft outcome in renal transplant recipients receiving Azathioprine-Prednisolone immunosuppression. The impact of the immunosuppressive drug, Cyclosporine on graft outcome in relation to established risk factors were examined among 116 cadaveric and 34 living related renal allograft recipients from our center. Histoincompatibility and pretransplant blood transfusions did not significantly affect graft survival among cadaveric transplant recipients. Similarly, graft survival was not significantly different between two haplotype-matched and less well-matched living-related graft recipients (75% versus 96.5% respectively). On the other hand, lymphocytotoxic antibodies remained a major risk factor for immunologically mediated graft loss among cadaveric graft recipients (48.0% versus 92.2% four year graft survival among those with and without antibodies respectively). These results suggest that Cyclosporine has abrogated some immunological risk factors in renal transplantation.

Adult↗
PubMed1992

Social and cultural aspects of organ donation in Asia.

In Asian countries, it is more difficult to obtain cadaver kidneys for renal transplantation because of certain socio-cultural beliefs and customs. The issues affecting living related kidney donation are more social than cultural. This is due to the web of family pressures and personal conflicts for both donor and recipient surrounding the donation. Important misconceptions and fears are: fear of death, the belief that removal of organ violates sanctity of decreased, concern about being cut up after death, desire to be buried whole, dislike of idea of kidneys inside another person, wrong concept of brain death, and the idea of donation being against religious conviction. In Singapore, with the introduction of the Human Organ Transplant Act (HOTA) in 1988, the number of cadaveric transplants have increased, including those from the Medical Therapy Act (MTA). HOTA and education have played pivotal roles in bringing about an increased yield of cadaveric kidneys. With the availability of living unrelated donor (LUD) transplants in India, our living related donor (LRD) transplant programme has suffered, because patients would rather buy a kidney from overseas than get a relative to donate one. Patients are also going to China for overseas cadaveric transplants where the kidneys come from executed convicts. People in countries like Hong Kong, Japan and the Philippines share the same Asian tradition of not parting with their organs after death. Muslim countries like Malaysia require the deceased to have earlier pledged his kidneys for donation prior to death before they can be harvested for transplantation at death.

Adult↗
PubMed1992

Can therapeutic interventions prevent chronic renal failure?

One way to prevent chronic renal failure (CRF) is to institute preventive measures against renal diseases in the general population. Patients with hereditary kidney diseases should have genetic counselling. Certain infections affecting or causing kidney diseases can be eradicated. People should be cautious in the use of analgesics and non-steroidal anti-inflammatory agents. Exposure to hydrocarbons, heavy metals and toxic gases should be avoided. Proper management of diabetes mellitus, gout, renal stones and hypertension can prevent renal damage. In patients with established renal disease, the following factors if treated or modified can prevent or ameliorate renal injury: glomerular hypertension, cell mediated proliferation, lipid induced proliferation, coagulation and thrombosis. Pregnancy in patients with renal disease should be well managed and termination advised if necessary. Reversible causes of renal failure as well as acute reversible elements can be removed or treated. Acute renal failure due to toxins can be avoided, although prevention requires awareness of association with renal failure. Prevention too depends on early detection of nephrotoxic injury like: greater awareness of hazards of environmental toxins, careful monitoring of dosage of nephrotoxic drugs and when possible, total avoidance of nephrotoxins should be the rule. Finally, in patients with glomerular disease, prevention or amelioration of glomerular damage with pharmacological agents have been achieved in some instances.

Genetic Counseling↗
PubMed1991

Cell-mediated immunity in patients on hemodialysis: relationship with hepatitis B carrier status.

We compared cell-mediated immune responses in two groups of patients on hemodialysis. One group of patients were chronic carriers of hepatitis B virus (HBV), and the patients of the other group were HBV antigen negative. Our results show that despite the presence of normal numbers of T cells and an increased CD4/CD8 ratio in both groups of patients compared to healthy controls (p less than 0.0001), only the group of patients who were chronic HBV carriers showed depressed lymphoproliferative responses to phytohemagglutinin (p less than 0.001) and concanavalin A (p less than 0.0001). In contrast, a control group of healthy adult HBV carriers showed normal T cell subsets and lymphoproliferative responses to mitogens, indicating that HBV infection per se did not result in depressed lymphoproliferative responses. These results further substantiate the notion that depressed cell-mediated immunity in chronic renal failure is an important factor in predisposing patients to HBV infection with subsequent development of the chronic carrier state.

Adult↗
PubMed1991

Seroprevalence of antibodies to the hepatitis C virus in Singapore.

The prevalence of antibodies to the hepatitis C virus (anti-HCV) in Singapore was assessed using a recombinant-based enzyme linked immunoassay system. 1004 serum samples were obtained from normal subjects (463), hemodialysis patients (112), hepatitis B virus (HBV) carriers (188), patients with hepatocellular carcinoma (HCC) (58) and patients with non-hepatitis B virus related liver diseases (183). Anti-HCV was found to be positive in 1.7% of healthy subjects, and in 20% of patients on regular hemodialysis. Three percent of HBV carriers were positive for anti-HCV. Twelve percent of patients with acute hepatitis with no known causes and 20% patients with chronic hepatitis with no known causes were positive for anti-HCV. Among patients with cirrhosis for which no known causes were found 33% were positive for anti-HCV. Thirty six percent of patients with HCC not associated with the presence of HBsAg were positive of anti-HCV. None of the patients with known causes of liver disease were positive for anti-HCV.

Adolescent↗
PubMed1991

Pharmacokinetics and nephrotoxicity of cyclosporine.

Cyclosporine (CsA) is a potent immunosuppressive agent which has dramatically improved graft and patient survivals in clinical solid organ transplantation. However, CsA nephrotoxicity (NTX) is the most frequent and serious side effect of CsA therapy and occurs in a significant proportion of patients. The clinical presentation of NTX is that of reduced creatinine clearance, elevation of serum creatinine and a disproportionate rise in blood urea. The clinical picture occurs as three syndromes, namely acute, subacute and chronic CsA NTX. Regardless of the clinical syndrome, the pathoaetiology of NTX is related to decline in renal blood flow and increase in renal vascular resistance probably due to CsA induced changes in renal haemodynamics. Unfortunately, the dose that yields an optimal therapeutic index, namely maximal efficacy with minimal toxicity has yet to be defined. Optimal dosing is confounded by not only inter and intraindividual variabilities in drug absorption, distribution and metabolism, but also by the lack of a clear relationship between drug efficacy and trough CsA level monitoring. This paper describes the pharmacokinetics and nephrotoxicity of CsA and evaluates various strategies to overcome this toxicity.

Absorption↗
PubMed1991

Maintenance haemodialysis in Singapore.

The chronic haemodialysis programme of the Singapore General Hospital started in 1968 as a hospital-based fully nurse-assisted programme. This has since expanded to include Self Dialysis and Home Dialysis programmes. Data of 425 patients who entered the dialysis programmes was analysed retrospectively. The major cause of end stage renal failure was chronic glomerulonephritis (52%). Almost half of the patients in the haemodialysis programme were patients on self-dialysis (49%). There were 157 withdrawals and 116 deaths. Survival has improved tremendously with the use of treated water for dialysis from 1981. The 5 year survival in an earlier group of patients dialysed with untreated water was 48% compared with 81% in a late group dialysed with treated water (p less than 0.001). The pattern of complications has also changed with a lower incidence of dialysis osteomalacia, hypertension, hepatitis and eradication of dialysis dementia.

Acute Kidney Injury↗
PubMed1991

Pattern of proteinuria in IgA nephritis by SDS-PAGE: clinical significance.

Of sixty patients with IgA nephritis, none had CRF at first examination, 13 developed CRF with creatinine above 1.6 mg/dl within 6 years. Among these patients who had analysis of proteinuria by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), 31 patients had middle molecular weight (MMW) proteinuria alone (pattern 1), 10 had MMW and Low MW (LMW) or tubular proteinuria (pattern 2), 10 had high MW (HMW) and MMW proteinuria (Pattern 3) and 9 had HMW, MMW and LMW proteinuria (Pattern 4). At the end of a follow up period of 6 years (1983-1989) patients with mixed proteinuria had a higher incidence of chronic renal failure (CRF), 11/29 (38%) compared to those with pattern 1 proteinuria, 2/31 (6%) (chi 2 = 8.7, p less than 0.005). Based on the glomerular selectivity index (GSI), 19 patients had nonselective proteinuria but they did not have a higher incidence of CRF. By the selectivity index (SI), 18 patients had nonselective proteinuria and they showed a significantly higher incidence of CRF. Compared to the 41 patients who did not have LMW proteinuria, 19 patients with LMW proteinuria had more severe proteinuria. After a follow-up period of 6 years, patients with LMW proteinuria had a higher incidence of CRF (10% versus 47%, p less than 0.001). The presence of LMW proteinuria indicates a less favourable outcome and the pattern of proteinuria as assessed by the SDS-PAGE appears to be a better prognostic index in IgA nephritis than the SI and the GSI.

Adult↗