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Biomedical subjects

D M Mitchell

Publications and source records attributed to D M Mitchell.

At least 73 records · Page 4Linked to original sources
PubMed1993

The effect of cigarette smoking on the development of AIDS in HIV-1-seropositive individuals.

OBJECTIVE: To determine whether HIV-1-seropositive cigarette smokers progress more rapidly to AIDS than HIV-1-seropositive non-smokers. SETTING: The genitourinary medicine outpatient department of St Mary's Hospital, London, which is a London University teaching hospital (tertiary care centre). SUBJECTS AND DESIGN: Case series of 84 individuals with AIDS who provided accurate details of their smoking habits before their AIDS-defining diagnosis. MAIN OUTCOME MEASURE: Progression time to AIDS in relation to smoking habit. RESULTS: Progression time to AIDS (all diagnoses) was significantly reduced in HIV-1-seropositive smokers: median time to AIDS was 8.17 months for smokers (n = 43) and 14.50 months for non-smokers (n = 41) (P = 0.003). Smokers developed Pneumocystis carinii pneumonia (PCP) more rapidly than non-smokers, with a median time to PCP of 9.0 months, compared with 16.0 months for non-smokers (P = 0.002). Smoking had no significant effect on progression time to AIDS when not due to PCP. CONCLUSION: Cigarette smoking by HIV-1-seropositive individuals is associated with a more rapid development of AIDS and should be discouraged.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Radiological progression in rheumatoid arthritis: how many patients are required in a treatment trial to test disease modification?

OBJECTIVE: To determine whether the number of patients required in a therapeutic trial that uses progression of radiological abnormalities as the outcome measure would be similar for multiple centres. METHODS: The progression of radiological damage to the fingers and wrists of patients with rheumatoid arthritis in five centres, three in North America and two in Europe, was examined. The reproducibility of repeated readings by the same and multiple observers was examined. The number of patients required in a two group trial was calculated for several combinations of power and significance. RESULTS: Scoring progression of radiological abnormalities in sequential films taken between 0.5 and 2.1 years was found to be highly reproducible. When the scores of a single reader were used the rate of change of radiological scores was similar in all centres. Based on the mean progression rate for all centres it was estimated that 153 patients in each group would be required to assure 90% power for detecting a 50% slowing of radiological progression at a significance of 0.05. Review of the experience in three trials showed a large variability in the radiological progression rates. CONCLUSION: The progression of scores for radiological damage in rheumatoid arthritis is relatively uniform in North America and Europe and thus the number of patients required in a trial would be similar. Experience in three trials showed that patient selection is of paramount importance in setting up a successful study.

Adult↗
PubMed1993

Relation of HIV-I in bronchoalveolar lavage cells to abnormalities of lung function and to the presence of Pneumocystis pneumonia in HIV-I seropositive patients.

BACKGROUND: HIV is present in bronchoalveolar lavage cells of some but not all HIV seropositive patients. Abnormalities of lung function have been described in such patients in the absence of clinically overt pneumonia or other respiratory infections. It is possible that the presence of HIV in alveolar macrophages could account for these abnormalities. It is also possible that the presence of HIV in alveolar macrophages contributes to immunosuppression and an increased incidence of opportunistic infections. METHODS: This was a prospective study of 157 HIV seropositive patients requiring diagnostic bronchoscopy for investigation of new respiratory symptoms, chest radiograph abnormality, or pneumonic illness. Presence of HIV in bronchoalveolar lavage cells obtained at diagnostic bronchoscopy was determined by polymerase chain reaction to detect proviral DNA and in vitro cocultivation to detect productive virus infection. With these two techniques the presence or absence of HIV in bronchoalveolar lavage was compared with the presence of abnormalities of lung function or presence of Pneumocystis pneumonia. RESULTS: HIV was detected in bronchoalveolar lavage cells in 65% of patients by means of the polymerase chain reaction and 59% with cocultivation. With both methods of detection there was no association between the presence or absence of HIV and the presence of Pneumocystis pneumonia; nor was there a relation between the presence of HIV and abnormalities of lung function. CONCLUSION: The presence of HIV in bronchoalveolar lavage cells does not predispose to an increased incidence of Pneumocystis pneumonia; nor does it contribute to abnormalities of lung function.

Bronchoalveolar Lavage Fluid↗
PubMed1993

Reduced carbon monoxide transfer factor (TLCO) in human immunodeficiency virus type I (HIV-I) infection as a predictor for faster progression to AIDS.

BACKGROUND: In addition to the acute fall in carbon monoxide transfer factor (TLCO) associated with Pneumocystis carinii pneumonia (PCP) or other opportunistic lung infections, reduced TLCO occurs in HIV-I seropositive individuals without active pulmonary disease. Abnormal TLCO, in the absence of lung disease, may be a surrogate marker of HIV-I induced immunosuppression and, therefore, a predictor for a more rapid progression to AIDS. METHODS: Eighty four individuals with AIDS, who had regular pulmonary function tests before the diagnosis of AIDS was made, were identified from a cohort of patients with HIV-I infection. None had evidence of active pulmonary disease at the time of initial pulmonary function testing. The relation between the time taken to progress to AIDS and initial pulmonary function tests was examined with life table survival analysis. RESULTS: Patients with a TLCO value of < 80% of predicted normal (n = 46) progressed significantly faster to AIDS, with a median time of 8.0 months compared with 16.5 months for those with a TLCO value of > or = 80% (n = 38). When stratified by AIDS defining diagnosis (PCP or non-PCP), median time to PCP was also significantly related to initial TLCO values (TLCO of < 80% = 9.0 months, TLCO of > or = 80% = 19.0 months). Reductions in other measurements of lung function (FEV1, FVC, KCO) were not temporally associated with the development of AIDS. CONCLUSIONS: HIV-I seropositive individuals with TLCO values of < 80% predicted and no evidence of lung disease progress more rapidly to AIDS than those with TLCO values of > or = 80%.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Serial pulmonary function tests in the diagnosis of P. carinii pneumonia.

The predictive value of serial versus isolated measurements of transfer factor for carbon monoxide (TLCO) in the diagnosis of pneumocystis carinii pneumonia (PCP) in a cohort of 474 HIV-1 seropositive patients, with all stages of HIV disease, was evaluated. Two groups of patients were studied, one group with serial lung function measurements (Group 1) and another with only a single set of measurements (Group 2). During the study period 118 patients performing serial tests developed a respiratory illness of which 58 were performing monthly and 60 three monthly measurements of lung function (Group 1). In 36 patients from Group 1, where PCP was diagnosed, monthly lung function tests showed a decrease in TLCO from 68% (+/- 3.2) (SEM), (8 weeks prior to illness), to 44% (+/- 2.5) predicted normal at presentation, whereas in 22 patients who did not have PCP, TLCO fell from 71% (+/- 4.5) to 57% (+/- 3.1). TLCO was thus reduced to lower values in these with PCP than in those without PCP (p < 0.05). A fall of TLCO of 5% from initial values when used as predictive for presence of PCP had a sensitivity of 75% and a specificty of 28% (positive predictive value 56%; negative predictive value 48%). TLCO was < 70% predicted in 72/78 patients with PCP who performed only single lung function tests (Group 2), which gave a sensitivity of 92% and a specificity of 71% as a diagnostic test for PCP when compared with the cohort as a whole. The positive predictive value was 34%, negative predictive value was 98%.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Antigenic specificity and subset analysis of T cells isolated from the bronchoalveolar lavage and pleural effusion of patients with lung disease.

Cellular infiltrates of bronchoalveolar lavage (BAL) and pleural effusion from patients with tuberculosis (TB) and lung cancer were characterized for the presence of different T cell subsets by phenotypic analysis. The specificity of the T cells for mycobacterial antigens was then compared for the two disease compartments. The composition of T cell subsets within the BAL, in contrast to pleural effusion cells (PEC), revealed evidence of sequestration of CD8+ cells. BAL T cells were found to be a predominantly CD29+ DR+ memory population of activated cells. Although polyclonal populations of BAL T cells proliferated poorly to Mycobacterium tuberculosis antigens, mycobacterial antigen-reactive monoclonal T cell populations could be derived from the alveolar compartment. Two clones were shown to recognize the 65-kD heat shock protein of mycobacteria, and one of these clones recognized a conserved sequence of the molecule. Several BAL-derived clones, responding to a mycobacterial soluble extract, did not, however, recognize purified mycobacterial antigens, previously identified as highly stimulatory for PEC-derived T cells. T cell clones, derived from PEC of two TB patients, responded to the 38-kD and 71-kD, as well as the 65-kD mycobacterial antigens. Examination of the activation requirements of BAL-derived T cell clones, specific for mycobacterial antigens, revealed that exogenous IL-2 was necessary for the T cells to sustain proliferation. This was in contrast to the mycobacterial antigen-reactive T cells cloned from PEC. These results suggest that T cell populations with distinct antigen specificities and activation requirements are present in BAL and PEC.

Antigens, Bacterial↗
PubMed1992

Comparison of polymerase chain reaction amplification of two mycobacterial DNA sequences, IS6110 and the 65kDa antigen gene, in the diagnosis of tuberculosis.

BACKGROUND: Knowledge of the sequences of mycobacterial genes and the availability of DNA amplification techniques have raised the possibility that identification of mycobacterial DNA may offer a rapid and specific diagnostic test for tuberculosis. The correlation between the presence of Mycobacterium tuberculosis DNA and clinical tuberculosis, however, is not known. This study compared the results of polymerase chain reaction amplification of two M tuberculosis DNA sequences, IS6110 and the gene encoding the 65kDa heat shock protein (65kDa Ag), from sputum, bronchoscopy washings, and bronchoalveolar lavage fluid and related these findings to the presence of active and past tuberculosis. METHODS: Highly specific primers were used for amplification of IS6110 and 65kDa Ag DNA. Analysis was performed on one or more samples from 87 patients. RESULTS: IS6110 DNA was identified in samples from all six patients with active tuberculosis, from 15 to 18 patients with past tuberculosis, from five of nine contacts of patients with tuberculosis, and from nine of 54 patients with lung disease unrelated to tuberculosis. The 65kDa Ag DNA was identified in samples from all patients with active and past tuberculosis, from contacts of patients with tuberculosis, and from 14 of 42 patients with non-tuberculous lung diseases. CONCLUSION: These data suggest that the presence of IS6110 DNA correlates more closely with a tuberculosis related diagnosis than that of 65kDa Ag DNA and that both DNAs are found in most subjects with past tuberculosis or contacts of patients with tuberculosis. This may limit the clinical usefulness of these tests.

Base Sequence↗
PubMed1992

Bronchopulmonary Kaposi's sarcoma in patients with AIDS.

BACKGROUND: Kaposi's sarcoma is the most common secondary neoplasm to complicate HIV infection and may cause pulmonary disease. METHODS: A prospective study was carried out in 140 consecutive patients who were HIV seropositive and required bronchoscopy for new respiratory symptoms of at least two weeks' duration, with either a chest radiographic abnormality or abnormality of pulmonary function. The patients were classified into those with single local endobronchial lesions of Kaposi's sarcoma or generalised widespread lesions. Before bronchoscopy all patients had routine simple pulmonary function tests and chest radiography. RESULTS: Thirty nine (21%) patients had evidence of cutaneous Kaposi's sarcoma. Nineteen of the 39 were found to have endobronchial Kaposi's sarcoma lesions at bronchoscopy, but none of those who did not have cutaneous Kaposi's sarcoma. Respiratory symptoms of cough and breathlessness and radiographic abnormalities were attributed to Kaposi's sarcoma in this group, except in four patients who had concomitant pneumocystis pneumonia. Eight patients had local endobronchial Kaposi's sarcoma lesions and 11 had extensive lesions. Patients with extensive lesions had more widespread radiographic abnormalities; four of the patients with local endobronchial lesions had normal chest radiographs. All patients had reduced transfer factor for carbon monoxide and transfer coefficient, whereas patients with extensive endobronchial lesions also had reductions in forced expiratory volume in one second and forced vital capacity. Median survival (with palliative chemotherapy with vincristine and bleomycin) was only seven months. In three patients who needed further diagnostic bronchoscopy endobronchial lesions had regressed while they were having chemotherapy. CONCLUSIONS: This study suggests that endobronchial Kaposi's sarcoma is a relatively common finding in patients with AIDS and is particularly common in patients with cutaneous Kaposi's sarcoma who present with respiratory illness. Endobronchial Kaposi's sarcoma causes respiratory disease and abnormalities of pulmonary function. Pulmonary Kaposi's sarcoma should be considered as a possible cause for respiratory illness in any patient with cutaneous Kaposi's sarcoma.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Pulmonary function in human immunodeficiency virus infection. A prospective 18-month study of serial lung function in 474 patients.

To investigate the development of a reduced DLCO in patients with HIV-related disease, we studied 474 HIV-seropositive patients and performed serial lung function measurements over 18 months. The mean values of DLCO at presentation were lower in patients with more advanced HIV disease compared with asymptomatic HIV-seropositive patients (DLCO 88% of predicted). When compared with the DLCO in asymptomatic HIV-seropositive patients, the DLCO had reduced values in patients with persistent generalized lymphadenopathy (PGL) (82% of predicted, p less than 0.05), acquired deficiency syndrome-related complex (ARC) (73% predicted, p less than 0.001), nonpulmonary Kaposi's sarcoma (KS) (72% of predicted, p less than 0.001), nonpulmonary complications of AIDS excluding KS (73% of predicted, p less than 0.001), pulmonary KS (63% of predicted, p less than 0.001), pulmonary mycobacterial infection (68% of predicted, p less than 0.05), pyogenic infection (70%, p less than 0.05), acute Pneumocystis carinii pneumonia (PCP; 49%, p less than 0.001), and following recovery from PCP (71%, p less than 0.001). Serial lung function measurements over 18 months revealed no change in DLCO within any patient group, and in particular there was no tendency for a gradual decline. Clinical deterioration due to the development of PCP was associated with a reduction in DLCO. Conversely, in patients recovering from PCP, there was a partial improvement in DLCO over 3 months. Zidovudine (AZT) use did not affect DLCO within any diagnostic group or the recovery in DLCO following PCP. However, cigarette smoking was associated with further reductions in DLCO in all patient groups and with an impaired recovery of DLCO following acute PCP.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Complex↗
PubMed1991

The progression of erosion and joint space narrowing scores in rheumatoid arthritis during the first twenty-five years of disease.

Erosions and cartilage destruction are nearly universal features in peripheral joints that have been chronically affected by rheumatoid arthritis. Scoring methods to measure the extent of these abnormalities in hands and wrists have been developed and have been thoroughly tested in several studies to establish their reproducibility. In this study, we utilized one of these scoring methods to examine the progression of radiologic damage as related to duration of disease. Two hundred ninety-two patients from 3 different participating centers in the Arthritis, Rheumatism, and Aging Medical Information System were included. Six hundred fifty films of the hands and wrists, obtained from 210 patients, were scored for erosions and joint space narrowing. The average annual rate of progression of the total radiologic score, which sums erosion and joint space abnormalities and has a maximum possible score of 314, was approximately 4 units per year over the first 25 years after onset; this progression was more rapid in the earlier years of disease and slightly slower in the later years. Data were insufficient to accurately determine the progression rate in disease of more than 25 years duration.

Arthritis, Rheumatoid↗
PubMed1991

Effect of HIV-1 and cytomegalovirus in bronchoalveolar lavage cells on the transfer factor for lung carbon monoxide in AIDS patients.

Abnormalities in pulmonary function tests have been observed in AIDS patients with pulmonary disease. In this study, the polymerase chain reaction (PCR) was used to determine if the reductions in transfer factor for lung carbon monoxide (TLCO) were due to the presence of HIV-1 or cytomegalovirus (CMV). HIV-1 was detected in cells from bronchoalveolar lavage (BAL) in 35 out of 60 (58%) of patients. The detection of HIV-1 had no significant effect on pulmonary function. CMV was detected in the BAL of 58% of patients in this study but CMV was the sole viral pathogen in the lung of only two out of 60 (3.3%) individuals. A significant reduction in TLCO was observed in individuals with PCP where CMV was also detected in the BAL. This study shows that reduction in TLCO in HIV-seropositive patients is not due to the presence of HIV-1 or CMV alone in BAL cells.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Diagnostic value of lung clearance of 99mTc DTPA compared with other non-invasive investigations in Pneumocystis carinii pneumonia in AIDS.

Various non-invasive investigations were carried out in patients infected with HIV who had respiratory symptoms with and without pneumocystis pneumonia (with pneumonia, n = 13 (five smokers); without pneumonia, n = 22 (13 smokers]. These included chest radiography; lung function tests (forced expiratory volume in one second, forced vital capacity; transfer factor and coefficient for carbon monoxide); arterial blood gas tensions; arterial oxygen saturation at rest and on exercise; and lung clearance of diethylenetriaminepenta-acetic acid labelled with technetium-99m (99mTc DTPA). The effect of scan time (seven v 45 minutes from peak counts) and subtraction of background counts were examined. There were no significant differences between the two groups in lung function tests or arterial blood gas tensions at rest. The median clearance half time of inhaled 99mTc DTPA for the first seven minutes from peak counts was 7.2 minutes for patients with pneumocystis pneumonia and 22 minutes for those without. The median arterial oxygen desaturation on exercise was 5% in patients with pneumocystis pneumonia and 2% in those without. 99mTc DTPA lung clearance was better than the other non-invasive tests in discriminating pneumocystis pneumonia from other pulmonary disorders in patients positive for HIV. A short scan time of seven minutes was as sensitive and specific as the longer scan time of 45 minutes, and this allows the clearance of 99mTc DTPA to become a rapid screening test.

Adult↗