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Biomedical subjects

M Youle

Publications and source records attributed to M Youle.

At least 73 records · Page 4Linked to original sources
PubMed1995

HIV-1 p17 synthetic peptide vaccine HGP-30: induction of immune response in human subjects and preliminary evidence of protection against HIV challenge in SCID mice.

An HIV-1 p17 subunit vaccine, HGP-30, was evaluated in 38 HIV-1 seronegative individuals in phase I clinical trials in U.K. and U.S.A. The vaccine preparation induced cytotoxic T-cell (CTL) (11/25) and lymphocyte proliferation responses to KLH (19/20) and HGP-30/p17 (24/29) as well as antibody responses to HGP-30 (29/38) and KLH (38/38). The CTL activity was observed in a higher number of vaccine recipients (9/18) in the lower dose groups (10 and 25 micrograms/kg) than the vaccine recipients (2/7) in the 50 and 100 micrograms/kg dose group. These observations suggest that the 10-25 micrograms/kg vaccine dose may preferentially induce TH1 cell responses. TH1 cell responses have been suggested as important in inducing protective cell mediated immunity. The CTL response has been shown to be CD8+. In a pilot study in SCID mice, HIV-1 virus challenge studies in mice reconstituted with cells from an HGP-30 immunized individual showed protection against virus challenge as compared to SCID mice reconstituted with cells from a non-immunized subject. These studies suggest that HGP-30 is capable of inducing protective cellular immunity.

AIDS Vaccines↗
PubMed1994

Characterization of HIV-1 strains isolated from patients treated with TIBO R82913.

The drug sensitivities of human immunodeficiency virus type 1 (HIV-1) isolates from a group of four untreated and seven TIBO R82913-treated patients were determined in a reverse transcriptase (RT) assay. Five of the treated patients harbored HIV-1 isolates with R82913 sensitivity comparable to that of the isolates of untreated patients, ranging from almost 2-fold higher sensitivity to 13-fold lower sensitivity than that of recombinant p66 RT. From one of the seven treated patients, an HIV-1 strain with a 20-fold reduced sensitivity to R82913 could be isolated; and from another patient, a strain with 100-fold reduced sensitivity (resistance) was isolated. The drug-resistant strain in this patient emerged after 3 weeks of treatment and was due to the Y188L mutation in its RT. On passaging the virus in cord blood lymphocytes, but not in CEM cells, the resistant virus was lost in favor of a different HIV-1 strain harboring the wild-type Y188 with a sensitivity to R82913 comparable to that of wild-type p66 RT. In several HIV-1 isolates (from treated and untreated patients), some HIV-2- and CIVgab-specific amino acids were found. One of these substitutions, that is, I/V179D (from an untreated patient), conferred a sevenfold reduced RT sensitivity to R82913.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Pharmacokinetics of R 82913 in patients with AIDS or AIDS-related complex.

R 82913, a tetrahydroimidazobenzodiazepinthione (TIBO) derivative with potent activity against human immunodeficiency virus 1 (HIV-1) in vitro, was given to 22 patients with AIDS or AIDS-related complex in a dose-escalating pilot study. Doses of 10 to 300 mg administered daily by intravenous infusion were well tolerated for up to 50 weeks, with no haematological or biochemical evidence of toxicity. Mean OKT4 cell count rose slightly during the second month of treatment when higher steady-state plasma concentrations of the drug were achieved. Median p24 antigen concentration fell by 41% during the first month of therapy. When the rise in p24 antigen before therapy was compared to the fall during treatment, end-point analysis showed a significant difference (p less than 0.03). The combination of potent antiretroviral activity in vitro and the observed effect on HIV p24 antigen and absence of toxicity in vivo indicate that R 82913 and related TIBO derivatives merit further study in the treatment of retroviral infections.

AIDS-Related Complex↗
PubMed1990

Treatment of acquired immune deficiency syndrome (AIDS)-related pneumonitis with foscarnet: a double-blind placebo controlled study.

A double-blind placebo controlled trial of foscarnet was conducted in 32 Human Immunodeficiency Virus (HIV) antibody positive male homosexuals with a presumed AIDS pneumonia. The study was designed to evaluate the importance of treating cytomegalovirus (CMV) as a possible lung pathogen of these patients and as a toxicity study of foscarnet. Trial subjects were randomised to receive either foscarnet or placebo as a continuous intravenous infusion for 2 weeks along with conventional therapy against Pneumocystis carinii (PC) pneumonia. Bronchoscopy or post-mortem showed PC to be present in 24 patients and the bronchoalveolar lavage fluid had early antigen foci of CMV in nine, five of these being double infections. The incidence of CMV infection in this group of patients was not sufficiently high to prove or disprove that treatment of CMV speeds recovery or improves prognosis in AIDS pneumonias. Overall however foscarnet was well tolerated with a slight increase in adverse reactions in the treated groups. This agent is therefore a relatively non-toxic drug to use in the treatment of established CMV disease.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Anti-CD4 autoantibodies and screening for anti-idiotypic antibodies to anti-CD4 monoclonal antibodies in HIV-seropositive people.

The cell-surface antigen CD4 is the major receptor for HIV. Anti-CD4 autoantibodies and anti-idiotypic antibodies to murine monoclonal anti-CD4 antibodies have been described in HIV-infected people. Ninety-seven sera from HIV-infected people at all stages of disease were examined for the presence of anti-idiotypic antibodies to three anti-CD4 monoclonal antibodies. None were found. The same sera were screened for antibodies reactive with soluble CD4, and five (5.2%) were positive. These antibodies did not recognize native CD4, and it is thought unlikely that they arise as anti-idiotypes to anti-gp120 antibodies.

Antibodies, Anti-Idiotypic↗
PubMed1990

The significance of the detection of cytomegalovirus in the bronchoalveolar lavage fluid in AIDS patients with pneumonia.

We performed a retrospective study on 112 patients with AIDS-related pneumonias who underwent bronchoscopy and in whom Pneumocystis carinii pneumonia (PCP) and/or cytomegalovirus (CMV) were identified in bronchoalveolar fluid (BAL). CMV was identified by detection of early antigen fluorescent foci (DEAFF) testing in cell cultures of BAL fluid. The short- and long-term survival of all patients was similar regardless of whether PCP, CMV or both were detected at bronchoscopy. Ten out of 14 patients with CMV alone and 13 out of 26 with both CMV and PCP were treated with anti-CMV therapy, but the short- and long-term mortality was similar to that in patients who had no specific antiviral therapy. Extrapulmonary recurrence of CMV (retinitis or gastrointestinal disease) occurred in 22% of patients with evidence of CMV in BAL compared with 16% of those with PCP alone, but this difference was not statistically significant and this recurrence rate was independent of anti-CMV therapy. Detection of CMV shedding from more than one site (BAL, urine, throat or blood) was associated with a worse prognosis at 3 months than in patients in whom CMV was detected in BAL alone. It does not appear that finding CMV shedding is a guide to the cause of pneumonia or an indication for treatment in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Pneumocystis carinii pneumonia treated with eflornithine in AIDS patients resistant to conventional therapy.

Eflornithine (DFMO) was used to treat 31 AIDS patients with confirmed Pneumocystis carinii pneumonia who had clinically failed treatment with pentamidine, sulphamethoxazole-trimethoprim or both agents as their first-line therapy. Twenty-one of 31 (68%) responded to second-line treatment with 400mg/kg per day of eflornithine. Five patients discontinued treatment because of bone marrow toxicity. Eflornithine appears to be a useful salvage therapy in patients failing first-line treatments.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Diagnosis, treatment and outcome of pneumonia in the acquired immune deficiency syndrome.

Fibreoptic bronchoscopy was performed in 43 of 52 consecutive patients with opportunistic pneumonia in the acquired immune deficiency syndrome (AIDS). The 15 patients in whom a likely pathogen was not found by bronchoscopy (including the nine not having the procedure) were treated for Pneumocystis carinii pneumonia (PCP) alone and all responded. In 11 of these a diagnosis of AIDS was confirmed because of an alternative opportunistic infection within 6 months. PCP was confirmed in 38 of the 52 patients and cytomegalovirus (CMV) was isolated from 15 patients. The lower the partial pressure of arterial oxygen (PaO2) on admission the more likely was a pathogen to be found by bronchoscopy. The admission PaO2 while the patient was breathing room air was the single most reliable prognostic indicator. The mean PaO2 for survivors was 9.6 kPa and 6.7 kPa for non-survivors (P less than 0.01 Student's t-test), with 50% mortality for patients with a PaO2 of less than 8 kPa on admission. Temperature and pulse rate were sensitive indicators of response to treatment, obviating the need for frequent arterial gas measurements and chest radiography. Our findings suggest that although fibreoptic bronchoscopy contributed little to the treatment and final outcome of the infection, it identified the causative pathogen in most patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The efficacy and toxicity of azidothymidine (AZT) in the treatment of patients with AIDS and AIDS-related complex (ARC): an open uncontrolled treatment study.

The efficacy and toxicity of oral azidothymidine has been studied in 145 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). The median survival time of AIDS patients on azidothymidine was 4.5 times higher when compared to a historical AIDS group who had not received the drug. This result must be interpreted with caution because of changes in treatment of HIV infection and growing awareness of AIDS which may have led to earlier diagnosis in the group treated with azidothymidine. The mortality was significantly higher in those patients who received transfusions and was particularly high in those who were transfused before azidothymidine. There was a significant difference in the occurrence of opportunistic infections in the patients who received transfusions compared with those who did not. AIDS patients treated immediately after an episode of Pneumocystis carinii pneumonia survived significantly longer than those in whom treatment was delayed for three months or more, and longer than those who were treated with azidothymidine because of another opportunistic infection or Kaposi's sarcoma. The T4 cell median counts increased in patients treated with azidothymidine reaching a peak at the end of the fourth month of treatment in the ARC group and at the end of the first month in the AIDS group with a subsequent fall in both groups. Sixty per cent of patients were p24 viral antigen positive at the start of treatment and 19 per cent of these patients had a fall of more than 50 per cent in antigen level while 32 per cent became antigen negative following treatment with azidothymidine. The mortality in the patients where the antigen disappeared or in whom there was a major fall of more than 50 per cent in antigen level was significantly less than in those where there was no change in antigen level. Twenty-nine patients were treated with azidothymidine because of skin Kaposi's sarcoma and in 17 tumour regressed or was stable. Thirty-two per cent of patients treated with azidothymidine became anaemic. Neutropenia occurred in 3 per cent of patients. Platelets increased initially after treatment but subsequently fell to thrombocytopenic levels in eight patients. Nine of 12 patients with thrombocytopenia before azidothymidine was commenced responded with an increased platelet count.

AIDS-Related Complex↗
PubMed1988

Effects of passive immunization in patients with the acquired immunodeficiency syndrome-related complex and acquired immunodeficiency syndrome.

Infection with the human immunodeficiency virus type 1 (HIV-1) is usually followed by a vigorous immune response that temporarily protects against disease progression. After a variable asymptomatic period, acquired immunodeficiency syndrome (AIDS)-related complex (ARC) and AIDS develop in most infected individuals. We have demonstrated that healthy HIV-1-infected individuals have neutralizing antibodies and a high titer of antiviral antibodies. In contrast, AIDS patients have undetectable levels of neutralizing antibodies, low titers of antiviral antibodies, and, frequently, HIV p24 antigenemia. These observations prompted us to attempt passive immunization in ARC and AIDS patients. Ten consistently viral-antigen-positive patients (mean, greater than 6 months) were treated, resulting in sustained clearance of p24 antigen. Patients either maintained or increased their antiviral antibody titers. The raised titers result from increased antibody synthesis by the recipients. Circulating CD4+ cell counts were unchanged after 2 months. By the third month none of these patients remained in hospital. As this treatment was of minimal toxicity, it merits wider evaluation in ARC and AIDS patients.

AIDS-Related Complex↗
PubMed1988

Restriction of sensitivity of HIV-1-antigen ELISA by serum anti-core antibodies.

Addition of varying concentrations of HIV-1-seropositive plasma to purified virus particles and soluble viral antigen preparation inhibited the detection of HIV-1-antigen by ELISA. The degree of inhibition on p24 antigen ELISA depended on the relative concentrations of viral antigen and anti-p24 antibodies in the mixtures. The relevance of these observations to clinical specimens was demonstrated when serial plasma samples from nine AIDS-related complex (ARC) patients in a clinical trial of foscarnet therapy were assayed for p24 antigen. Six (66.6%) out of nine patients were negative on screening. However, when their plasma was centrifuged through a sucrose solution, virus particles were pelleted that were depleted of anti-p24 and virus-specific p24 antigen was detected in resuspended pellets obtained from samples from all six patients. Eight serial samples collected from a male homosexual over 50 weeks following seroconversion were also subjected to the separation procedure. HIV-1-antigen was detected in all eight samples. In the light of these observations, the application of the separation technique in monitoring the efficacy of zidovudine or other anti-retroviral therapy should reveal more precise antigen levels in patients who otherwise appear to be antigen-negative in HIV-antigen assays. We propose that the natural history of HIV infections follows a pattern of chronic viral infection with continuous shedding of virus particles circulating as immune complexes.

AIDS-Related Complex↗