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Biomedical subjects

C A Sabin

Publications and source records attributed to C A Sabin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Long-term follow-up of antiretroviral-naive HIV-positive patients treated with nevirapine.

This article reports on the extended follow-up of 125 antiretroviral (ARV)-naive patients treated with nevirapine (NVP) in the United Kingdom. The patients have been observed for a median of 1.8 years after starting NVP (range, 4 days-2.7 years). Baseline CD4 counts and HIV RNA levels were 210 (interquartile range, 130 - 335) cells/mm3 and 4.86 (range, 4.52-5.26) log10 copies/ml, respectively. Eleven patients (9.0%) developed a rash thought to be related to NVP, of whom 4 permanently discontinued NVP. Twenty-four months after starting NVP, RNA levels had dropped by a median of 2.32 log10 copies/ml and CD4 counts increased by a median of 143 cells/mm3. In all, 96 patients had at least one viral load measured <500 copies/ml, a median of 2.8 months after starting NVP. RNA levels rebounded >500 copies/ml in 37 of these patients, on average 2 years after initial response. In conclusion, in ARV-naive patients, NVP is generally well tolerated and long-term response rates are good.

Adult↗
PubMed2001

Reasons for modification and discontinuation of antiretrovirals: results from a single treatment centre.

OBJECTIVE: To describe the reasons for, and factors associated with, modification and discontinuation of highly active antiretroviral therapy (HAART) regimens at a single clinic. SUBJECTS: A total of 556 patients who started HAART at the Royal Free Hospital were included in analyses. Modification was defined as stopping or switching any antiretrovirals in the regimen, whereas discontinuation was defined as the simultaneous stopping of all antiretrovirals included in the initial regimen. Reasons were classified as immunological/virological failure (IVF) and toxicities and patient choice/poor compliance (TPC). RESULTS: The median CD4 count at starting HAART was 171 x 10(6) cells/l and viral load 5.07 log copies/ml. During a median follow-up of 14.2 months, 247 patients (44.4%) modified their HAART regimen, 72 due to IVF (29.1%) and 159 due to TPC (64.4%) and a total of 148 patients (26.6%) discontinued HAART. Older patients were less likely to modify HAART [relative hazard (RH), 0.73 per 10 years; P = 0.0008], as were previously treatment-naive patients (RH, 0.65; P = 0.0050), those in a clinical trial (RH, 0.64; P = 0.027) and those who started nelfinavir (RH, 0.57; P = 0.035). Patients who started with four or more drugs (RH, 2.21, P < 0.0001), who included ritonavir in the initial regimen (RH, 1.41; P = 0.035) or who had higher viral loads during follow-up (RH per log increase, 1.51; P < 0.0001) were more likely to modify HAART. CONCLUSIONS: There was a high rate of modification and discontinuation of HAART regimens in the first 12 months, particularly due to toxicities, patient choice or poor compliance.

Antiretroviral Therapy, Highly Active↗
PubMed2001

The virological response to highly active antiretroviral therapy over the first 24 weeks of therapy according to the pre-therapy viral load and the weeks 4-8 viral load.

OBJECTIVES: To describe the viral response to HAART by weeks 4 and 8 in previously antiretroviral-naive patients. To assess whether the weeks 4 or 8 viral loads are useful predictors of viral suppression by week 24. DESIGN: A large clinical database including 453 antiretroviral-naive patients whose plasma viral load was monitored every 4 weeks. METHODS: Observed probabilities of achieving a viral load < or = 500 copies/ml by week 24 (days 84-168) from starting highly active antiretroviral therapy (HAART) were calculated according to viral loads at weeks 4 and 8. RESULTS: A total of 42.4% of patients (153/361) reached < or = 500 copies/ml viral load by week 4 and 70.4% (245/348) by week 8. Viral suppression below 500 copies/ml by 4-8 weeks was similar irrespective of the pre-HAART viral load. In patients with viral loads above 10000 copies/ml at week 4, 60.6% (20/33) achieved < or = 500 copies/ml by week 24. In patients with viral loads still above 10000 copies/ml at week 8, only 42.3% (11/26) achieved < or = 500 copies/ml by week 24, and only 33.3% (3/9) maintained viral suppression below 500 copies/ml to week 48. CONCLUSION: Viral loads at weeks 4 and 8 should be monitored to detect early signs of low subsequent viral suppression. For previously antiretroviral-naive patients whose viral loads after 8 weeks of HAART are still above 10000, there is an urgent need to assess adherence to therapy, drug levels and resistance, so management can be modified accordingly to reduce the rate of week 24 virological failure.

Adult↗
PubMed2001

Assessing the relationship between productivity levels and severity of haemophilia.

In this study, we assessed whether severity of haemophilia was associated with levels of productivity. Productivity levels were assessed by sending a 'time-use' questionnaire to 228 individuals with mild, moderate and severe haemophilia. The results showed that, after adjusting for differences in age and HIV serostatus, there were no differences between individuals with severe and mild/moderate haemophilia in terms of completed levels of education, employment status, absenteeism from work over the previous 2 weeks, the number of hours each week spent performing unpaid tasks and how efficiently individuals performed these tasks. The data did suggest, however, that a significantly larger proportion of individuals with severe haemophilia (32%) required help from family or friends to perform routine household tasks each week than individuals with mild/moderate haemophilia (13%). In conclusion, it is possible that individuals with severe haemophilia have similar levels of productivity compared to individuals with mild/moderate haemophilia or that treatment with secondary prophylaxis has helped to reduce differences between the two patient groups.

Activities of Daily Living↗
PubMed2001

Assessing the cost-effectiveness of HAART for adults with HIV in England.

OBJECTIVE: To assess the cost-effectiveness of highly active antiretroviral therapy (HAART) compared with two nucleoside reverse transcriptase inhibitors (NRTIs) for HIV infected individuals. DESIGN: Different data sources on the clinical effects and costs of treatments were combined using a Markov model. SETTING: English HIV treatment centres. Perspective UK public finance. INTERVENTIONS: HAART - dual NRTI therapy plus a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor - vs. dual NRTI therapy. PARTICIPANTS: Hypothetical cohorts of 1000 individuals infected with HIV. Outcome measures Projected life expectancy, cost-effectiveness in UK pound per life-year saved and per quality-adjusted life-years (QALYs) saved. RESULTS: Assuming a 2-year additional treatment effect of therapy with HAART produced incremental cost-effectiveness ratios of pound14 602 per life-year saved and pound17 698 per QALY saved. CONCLUSIONS: The results were sensitive to a number of assumptions including the cost of HAART and the discount rate, but they suggest that the use of HAART in England is at least moderately cost-effective compared with treatment with two NRTIs alone.

Adult↗
PubMed2001

Human tenon's fibroblast-produced ifnbeta and the prevention of t-cell apoptosis.

PURPOSE: Fibroblast-T-cell interactions may contribute to the development of chronic inflammation, a risk factor for trabeculectomy failure. This study was undertaken to determine whether normal and growth-arrested human Tenon's fibroblasts (HTF) can prevent cytokine deprivation-mediated T-cell apoptosis through the secretion of interferon (IFN)beta. METHODS: HTF were used either untreated or pretreated with mitomycin-C (MMC; 0.1 or 0.4 mg/ml) or 5-fluorouracil (5FU; 25 or 50 mg/ml). IL2-deprived T cells were cocultured with HTF. T-cell viability was measured at specific time points. Human Tenon's fibroblast-conditioned medium was used either untreated or treated with a neutralizing antibody against IFNbeta to block its action, after which IL2-deprived T cells were added and T-cell viability was measured. An image analysis system was used to determine the production of IFNbeta by either untreated or MMC-treated HTF. RESULTS: T-cell viability was significantly greater when T cells were cocultured with both untreated and growth-arrested HTF than when T cells were cultured alone (day 7, P = 0.0001). Neutralizing the action of IFNbeta blocked HTF-mediated T-cell rescue from apoptosis. Both untreated and growth-arrested HTF secrete IFNbeta, and MMC at 0.4 mg/ml appeared to increase IFNbeta production. CONCLUSIONS: Cytokine deprivation-mediated T-cell apoptosis can be prevented by the action of IFNbeta secreted by both normal and growth-arrested HTF, which suggests that growth-arrested HTF can still participate in an aggressive wound-healing reaction by mediating a persistent inflammatory phase. This may partly explain why some trabeculectomies fail in high-risk patients, despite the use of antimetabolites.

Apoptosis↗
PubMed2000

Relationship between IgM antibody to human cytomegalovirus, virus load, donor and recipient serostatus, and administration of methylprednisolone as risk factors for cytomegalovirus disease after liver transplantation.

A retrospective study was performed on a selected cohort of 40 liver transplant recipients derived from the previous prospective follow-up of 162 liver transplant patients. The criterion for selection of this cohort was the presence of human cytomegalovirus (HCMV) DNAemia after transplantation, as determined by qualitative polymerase chain reaction (PCR). These 40 patients were followed longitudinally by quantitative PCR and by the new recombinant antigen-based AxSYM immunoassay for IgM to HCMV. The detection of IgM to CMV after transplantation was significantly associated with the development of HCMV disease in patients who had evidence of active HCMV replication in the blood by PCR (P=.01). On the basis of multivariate logistic regression analyses, the maximum titer of IgM detected after transplantation was a risk factor that was independent of augmented methylprednisolone and donor seropositivity. However, in multivariate analyses, elevated virus load continued to be the predominant risk factor for progression to HCMV disease.

Anti-Inflammatory Agents↗
PubMed2000

The impact of protease inhibitor-containing highly active antiretroviral therapy on progression of HIV disease and its relationship to CD4 and viral load.

OBJECTIVE: To compare the rate of disease progression according to viral load and CD4 cell count in patients receiving or not receiving highly active antiretroviral therapy (HAART), defined as protease inhibitor-containing regimens. DESIGN: An observational study, with prospectively collected data. METHODS: All patients attending the HIV Outpatient clinic as of 1 January 1995 (n = 2083) were included. Follow-up was until the first AIDS-defining event or death. Associations between viral load or CD4 cell count and disease progression were assessed using a person-years approach. Event rates were compared using Poisson regression analysis; a multivariate model was used to assess the independent effects of CD4, viral load and treatment group on event rates and to consider interactions between these variables. RESULTS: The event rates increased with lower CD4 cell count and higher viral load for both treatment groups and were generally lower in the HAART group. In a multivariate analysis, lower CD4 cell counts and higher viral loads remained significantly associated with disease progression, irrespective of treatment group. However, the event rate was significantly lower for the HAART group compared with the control group (relative rate 0.53, P < 0.001). CONCLUSIONS: HAART-treated patients with high viral loads and CD4 cell counts experienced reduced disease progression compared with individuals with the same CD4 cell count and viral load not receiving HAART. Consequently, the short-term prognosis associated with viral load levels and CD4 cell counts may differ in patients on HAART. Whether this effect will be observed with non-protease-inhibitor-containing HAART is not known at this time.

Adolescent↗
PubMed2000

Pre-AIDS mortality and its association with HIV disease progression in haemophilic men, injecting drug users and homosexual men.

OBJECTIVE: To study pre-AIDS mortality and its association with HIV disease progression in different exposure groups with known intervals of HIV seroconversion. DESIGN AND METHODS: The type and rate of pre-AIDS deaths were assessed in 111 HIV-infected haemophilic men followed in London, and 118 injecting drug users and 158 homosexual men followed in Amsterdam. In each group, the association between CD4+ T-cell count, HIV RNA and pre-AIDS mortality was studied using proportional hazards analysis. RESULTS: By 10 years after seroconversion 7.3% of the haemophilic men had died without AIDS and 38.2% had developed AIDS. These figures were 20.2 and 30.5% for injecting drug users, and 8.0 and 55.0% for homosexual men. The major causes of pre-AIDS mortality appear to differ in the three exposure groups. The risk of pre-AIDS death tended to increase with decreasing CD4 cell count and increasing HIV RNA levels in injecting drug users and homosexual men. In men with haemophilia the associations were less obvious, although the log-transformed CD4 cell count was predictive for pre-AIDS death. CONCLUSIONS: Pre-AIDS deaths occur and are at least partially related to HIV disease progression irrespective of how individuals became infected. Because of the longer life expectancy due to highly active antiretroviral therapy (HAART), pre-AIDS deaths are likely to show a further increase. Methods to incorporate these intermediate outcomes should be considered in the estimation of the size of the HIV epidemic and in the survival analysis of HIV-infected individuals. Prevention and treatment of non-AIDS infections, especially hepatitis C virus infection, and cancers will become increasingly important in HIV-infected individuals. The interaction between these therapies and HAART should be closely monitored.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Substantial correlation between HIV type 1 drug-associated resistance mutations in plasma and peripheral blood mononuclear cells in treatment-experienced patients.

The correlation of detectable HIV-1 drug resistance mutations in plasma and PBMCs in patients extensively treated with all antiretroviral drug classes has not been fully elucidated. The detection of mutations in PBMCs may reveal resistant HIV-1 associated with past therapies. In addition, these measures in PBMCs may have a practical value when plasma virus is at low levels that are difficult to detect with current assays. The reverse transcriptase (RT) and protease (P) genes were analyzed for drug resistance, using an in-house method carried out on 36 paired samples of plasma and PBMCs from 12 treatment-experienced patients in order to investigate resistance in the two compartments. When viruses in plasma and PBMCs were analyzed by patient, the mean of the Cohen kappa values was 0.728 (substantial agreement). When viruses were analyzed by codon the mean of the Cohen kappa values was 0.715 (substantial agreement). Baseline samples were concordant at 280 of 288 (97%) codons analyzed. This study shows that a minority of mutations associated with previous therapy can be detected in PBMCs and not in plasma. Overall, mutations in plasma and PBMCs showed a substantial correlation in extensively treated patients, suggesting that either compartment is suitable for the detection of mutations as a virological guide for clinical care.

Anti-HIV Agents↗
PubMed2000

Changes in the natural history of cytomegalovirus retinitis following the introduction of highly active antiretroviral therapy.

OBJECTIVE: To determine the effect of highly active antiretroviral therapy (HAART) on the natural history of cytomegalovirus (CMV) retinitis. DESIGN AND PARTICIPANTS: Retrospective analysis of 103 consecutive patients diagnosed with CMV retinitis between 1990 and 1998. SETTING: Specialist HIV medicine department of a London hospital. MAIN OUTCOME MEASURES: Incidence of CMV retinitis, time to death following diagnosis, episodes of progression, incidence of inflammatory complications. The date of first use of HAART was January 1995. Data were censored on 30 June 1998. RESULTS: The incidence of CMV retinitis has declined dramatically following the introduction of HAART. Survival following CMV retinitis increased from a median of 0.65 years prior to 1995 to a median of 1.07 years after this date (P = 0.004). In multivariate analyses HAART was independently associated with improved survival (P = 0.02) and the association with year of diagnosis was no longer significant, suggesting that this effect is predominantly due to HAART. None of the patients receiving HAART experienced progression after 6 months of treatment. Complications of retinitis such as retinal detachment, uveitis and optic atrophy occurred in 39% of patients. The rare inflammatory complications of vitritis and cystoid macular oedema occurred only in recipients of HAART. CONCLUSIONS: The introduction of HAART has had a major impact on the natural history of CMV retinitis with improved survival time and decreased risk of progression following diagnosis. However, immune reconstitution may be associated with inflammatory complications which can result in significant visual loss in the absence of active CMV disease.

AIDS-Related Opportunistic Infections↗
PubMed2000

Prospective study of human betaherpesviruses after renal transplantation: association of human herpesvirus 7 and cytomegalovirus co-infection with cytomegalovirus disease and increased rejection.

BACKGROUND: Human herpesvirus 6 (HHV-6) and HHV-7 are two lymphotropic herpesviruses, which, like cytomegalovirus (CMV), have the potential to be pathogenic in immunocompromised individuals. We have conducted a prospective investigation to compare the natural history of HHV-6 and HHV-7 infection with that of CMV after renal transplantation. METHODS: Polymerase chain reaction was used to identify infections and quantify the viral load of CMV, HHV-6, and HHV-7 in peripheral blood samples from 52 renal transplant recipients. Betaherpesvirus infections were related to defined clinical criteria obtained by detailed examination of the clinical records of each patient for the immediate 120-day posttransplant period. RESULTS: CMV was the most commonly detected virus after transplant (58% of patients), followed by HHV-7 (46%) and HHV-6 (23%). Examining the time to first polymerase chain reaction positivity, HHV-7 infection was detected earlier than CMV (P=0.05). The median maximum CMV viral load was significantly higher than those for HHV-6 (P=0.01) and HHV-7 (P<0.0001) and a trend for HHV-7 viral load to be greater than HHV-6 (P=0.08). Clinicopathological analyses revealed that, in those patients with rejection, HHV-7 was associated with more episodes of rejection (P=0.02). In addition, there was a significant increase in CMV disease occurring in patients with CMV and HHV-7 co-infection compared to those with CMV infection only (P=0.04). CONCLUSIONS: HHV-7 should be further investigated as a possible co-factor in the development of CMV disease in renal transplant patients and may potentially exacerbate graft rejection. No clear pathological role was observed for HHV-6.

Betaherpesvirinae↗
PubMed2000

Application of viral-load kinetics to identify patients who develop cytomegalovirus disease after transplantation.

BACKGROUND: Cytomegalovirus (CMV) continues to be a major problem post-transplantation; early markers for predicting patients at risk of CMV disease are needed. Peak CMV load in the blood correlates with CMV disease but frequently occurs too late to provide prognostic information. METHODS: 359 transplant recipients (162 liver, 87 renal, and 110 bone marrow) were prospectively monitored for CMV DNA in the blood with qualitative and quantitative PCR. 3873 samples were analysed. The CMV load in the first PCR-positive sample and the rate of increase in CMV load in blood during the initial phase of replication were assessed as risk factors for CMV disease using logistic regression. FINDINGS: 127 of the 359 patients had CMV DNA in the blood and 49 developed CMV disease. Initial viral load correlated significantly with peak CMV load (R2=0.47, p=<0.001) and with CMV disease (odds ratio 1.82 [95% CI 1.11-2.98; p=0.02; 1.34 [1.07-1.68], p=0.01, and 1.52 [1.13-2.05], p=0.006, per 0.25 log10 increase in viral load for liver, renal, and bone-marrow patients, respectively). The rate of increase in CMV load between the last PCR-negative and first PCR-positive sample was significantly faster in patients with CMV disease (0.33 log10 versus 0.19 log10 genomes/mL daily, p<0.001). In multivariate-regression analyses, both initial CMV load and rate of viral load increase were independent risk factors for CMV disease (1.28 [1.06-1.52], p=0.01, per 0.25 log10 increase in CMV load and 1.52 [1.06-2.17], p=0.02, per 0.1 log10 increase in CMV load/mL daily, respectively). INTERPRETATION: CMV load in the initial phase of active infection and the rate of increase in viral load both correlate with CMV disease in transplant recipients; in combination, they have the potential to identify patients at imminent risk of CMV disease.

Cytomegalovirus↗
PubMed2000

Two decades of HIV infection in a cohort of haemophilic individuals: clinical outcomes and response to highly active antiretroviral therapy.

OBJECTIVES: Many haemophilic individuals infected with HIV died before receiving antiretroviral therapy (ART). Most who remain alive are chronically infected with hepatitis C virus (HCV), which has implications for their prognosis and choice of ART. The clinical status of a cohort of HIV-positive haemophilic men is reported together with their response to highly active antiretroviral therapy (HAART). DESIGN: Longitudinal cohort study. SETTING: A comprehensive care haemophilia centre. PATIENTS: A group of 111 haemophilic men who seroconverted to HIV in the period 1979 to 1985. RESULTS: The cohort has been followed since 1979. By 30 April 1999, 57 of the 111 men had developed AIDS and 65 had died: Kaplan-Meier rates of 57.0% [95% confidence interval (CI) 46.9-67.0) and 65.1% (95% CI 52.7-77.4) by 19.5 years, respectively. AIDS rates have declined since 1997 but death rates have remained high, largely owing to deaths from non-HIV-related causes. Thirty-five patients remain alive and under follow-up at the clinic. The 28 men who had received ART had lower CD4 cell counts than the seven patients who had not received ART, but the two groups were otherwise similar. In total, 21 patients are known to have started HAART while under care at the centre. By 10-12 months after starting HAART, viral loads dropped by 2.06 log10 copies/ml and CD4 cell counts increased by 60 x 10(6) cells/l. In 10 out of 18 patients with viral loads initially > 400 copies/ml, a viral load below this level was attained; four had changed therapy at the time. CONCLUSIONS: While the decision to initiate HAART in haemophilic men should be made carefully because of the possible adverse events, our results suggest that a good response rate was achieved in this group of men.

Anti-HIV Agents↗
PubMed2000

Reduction in human immunodeficiency virus type 1 mutations associated with drug resistance after initiating new therapeutic regimens in pretreated patients.

The objective of this study was to investigate the effect of initiating a salvage-therapy regimen on resistant viruses in heavily treated patients infected with human immunodeficiency virus type 1 (HIV-1). Nineteen patients receiving multiple antiretroviral drugs were tested for HIV-1 mutations associated with drug resistance by using an in-house method at baseline and at weeks 2, 4, and 8 of the salvage-therapy regimen. For the majority of mutations analyzed, the mean number of detectable mutations at baseline was significantly higher than the mean at weeks 2, 4, and 8 of salvage therapy. Introducing new and more potent therapy reduces the number of detectable drug resistance-associated mutations within 8 weeks, and no evidence was found that the new therapy promoted the emergence of novel mutations.

Anti-HIV Agents↗