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Biomedical subjects

H Chambers

Publications and source records attributed to H Chambers.

14 recordsLinked to original sources
PubMed1992

Kinetic studies of the mechanism of thrombocytopenia in patients with human immunodeficiency virus infection.

BACKGROUND: Isolated thrombocytopenia accompanied by increased amounts of platelet-associated antibody is a common manifestation of human immunodeficiency virus (HIV) infection, and the thrombocytopenia often improves with zidovudine. It is not clear whether the mechanism of HIV-related thrombocytopenia primarily involves autoimmune destruction of platelets or reduced platelet production by megakaryocytes. METHODS: We studied the survival of 111In-labeled autologous platelets and performed platelet imaging in 24 men with isolated HIV-related thrombocytopenia (16 who received no treatment and 8 who received zidovudine). We also studied 20 HIV-infected men with normal platelet counts (10 who received no treatment and 10 who received zidovudine) and studied 12 healthy seronegative men as controls. RESULTS: Mean (+/- SD) platelet survival was significantly decreased in both the untreated and the zidovudine-treated patients with HIV-related thrombocytopenia (to 92 +/- 33 and 129 +/- 44 hours, respectively; both P < 0.001), as compared with the normal controls (198 +/- 15 hours). Mean platelet survival was also significantly decreased in the HIV-infected patients with normal platelet counts (untreated, 162 +/- 23 hours, P < 0.01; zidovudine-treated, 166 +/- 35 hours, P < 0.05). Imaging studies, however, revealed no evidence of increased clearance of autologous platelets in the liver or spleen in any of these groups. Mean platelet production was significantly depressed in the untreated patients with thrombocytopenia (23,000 +/- 11,000 platelets per cubic millimeter per day, P < 0.001) as compared with the healthy controls (45,000 +/- 6,000 per cubic millimeter per day). Mean platelet production was significantly increased, however, in the men treated with zidovudine, both in those with thrombocytopenia (60,000 +/- 31,000 platelets per cubic millimeter per day, P < 0.01 vs. controls) and in those without thrombocytopenia (68,000 +/- 22,000 per cubic millimeter per day, P < 0.01). CONCLUSIONS: Although there was a moderate reduction in platelet survival in HIV-infected persons, these patients, regardless of platelet counts, also had decreased production of platelets, possibly due to viral infection of the megakaryocytes. Zidovudine appears to improve platelet production.

Blood Platelets↗
PubMed1991

Borderline susceptibility to antistaphylococcal penicillins is not conferred exclusively by the hyperproduction of beta-lactamase.

Staphylococcus aureus strains bearing the 17.2-kb beta-lactamase plasmid pBW15 and belonging to phage group 94/96 exhibit borderline susceptibility to the antistaphylococcal penicillins. Borderline susceptibility within phage group 94/96 is thought to be mediated by the hyperproduction of type A staphylococcal beta-lactamase. Evaluation of 84 non-94/96 phage type S. aureus strains that also produced the type A enzyme identified 7 additional hyperproducing strains. However, none of these isolates contained pBW15, and only one met the criteria for borderline susceptibility. To determine the role of pBW15 and the 94/96 phage type in the expression of borderline susceptibility, pBW15 was transformed in two plasmid-free, penicillin-susceptible strains, one of which belonged to phage group 94/96. Penicillin MICs for both transformants and quantitative beta-lactamase activity were comparable to those for the parent pBW15-containing strain. A fourfold difference in the oxacillin MICs for the 94/96 and non-94/96 phage type transformants (1.0 and 0.25 microgram/ml, respectively) was identified, and only the 94/96 phage type transformant met the criteria for borderline susceptibility. Chromosomal DNA from borderline-susceptible phage group 94/96 strains did not hybridize with a probe for mecA, and the beta-lactam binding affinity of PBPs 1, 2, 3, and 4 from a penicillin-susceptible 94/96 phage type strain and a non-94/96 phage type strain were comparable. Although hyperproduction of the type A beta-lactamase appears to be necessary for the expression of borderline susceptibility within certain phage group 94/96 strains, beta-lactamase production of a comparable magnitude by a group of S. aureus strains belonging to other phage types does not confer borderline susceptibility. These data suggest that borderline susceptibility is not solely due to the hyperproduction of beta-lactamase.

Bacterial Proteins↗
PubMed1989

Pathophysiology of thrombocytopenia associated with HIV infection in homosexual men. A preliminary report.

The pathophysiology of HIV associated immune thrombocytopenia (HIV-ITP) and its response to AZT was investigated. Using autologous 111Indium-labelled platelets, platelet kinetic were analysed in two patient groups. Group 1 (untreated) was comprised of 13 patients with HIV-ITP. Group 2 (AZT) was comprised of 6 patients with a history of HIV-ITP prior to starting AZT. These patients were studied following a rise in their platelet count on AZT. Platelet survivals in both groups were shortened compared to controls, however there was no significant difference between the 2 groups. However platelet turnover rates were significantly depressed in Group 1 compared to Group 2 (P less than 0.05) and control values (P less than 0.05). The platelet count correlated with platelet turnover in Group 1 but not in AZT treated patients. Thus patients with HIV-ITP appear to have both shortened survivals and suppressed platelet production. The mechanism of the latter is unknown, but the increased turnover rate seen with AZT suggests it is a direct or indirect effect of the HIV virus.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Staphylococcus aureus bacteremia and recurrent staphylococcal infection in patients with acquired immunodeficiency syndrome and AIDS-related complex.

PURPOSE: An increased incidence of Staphylococcus aureus bacteremia has recently been described in patients with the acquired immunodeficiency syndrome (AIDS). However, other risk factors for community-acquired S. aureus bacteremia (including intravenous drug abuse and lymphedema) were present in nearly all these AIDS-related cases of S. aureus infection. Our purpose was to review cases of S. aureus bacteremia that occurred in patients with AIDS or AIDS-related complex (ARC) who did not have a recent history of intravenous drug use, lymphatic obstruction, or neutropenia. PATIENTS AND METHODS: Patients at San Francisco General Hospital between October 1984 and October 1987 with blood culture results positive for S. aureus were identified. A review of this group revealed 22 cases of S. aureus bacteremia that occurred in 18 patients with an underlying diagnosis of AIDS or ARC, none of whom had a recent history of intravenous drug use, lymphedema secondary to Kaposi's sarcoma, or neutropenia. RESULTS: An intravenous catheter was the single most important risk factor for S. aureus bacteremia and was identified as the source for bacteremia in 16 (73 percent) of the 22 episodes. Based on 1986 outpatient clinic records, we calculated an incidence of S. aureus bacteremia occurring in non-intravenous-drug-using male AIDS or ARC patients, 18 to 44 years old, that was 5.4 episodes/1,000 patients. Although the mean duration of appropriate antibiotic therapy was 18 days, late metastatic complications of S. aureus bacteremia occurred in six (35 percent) of 17 AIDS/ARC patients who survived initial antibiotic therapy. CONCLUSION: Non-intravenous-drug-using AIDS and ARC patients (especially those with indwelling venous catheters) appear to be at high risk for S. aureus bacteremia, with a higher late metastatic complication rate than that reported for recent historical control subjects.

AIDS-Related Complex↗
PubMed1987

Psychological problems associated with diagnosis and treatment of lymphomas. I: Retrospective study.

Patients treated for Hodgkin's disease and non-Hodgkin's lymphoma have a better prognosis than other patients with cancer so may have a lower prevalence of psychological and social morbidity. Trained interviewers used standardised methods to assess 90 patients at a mean of 32 months after the diagnosis of Hodgkin's disease or non-Hodgkin's lymphoma. Chemotherapy and radiotherapy had commonly caused adverse effects including hair loss, vomiting, nausea, and loss of appetite. Although most patients were free of disease and not receiving treatment at follow up, some still suffered from a lack of energy (31 patients), loss of libido (19), irritability (22), and tiredness (19); 30 patients complained of continued impairment of thinking or disturbance of short term memory. After diagnosis 21 patients had suffered from an anxiety state or depressive illness, or both, while 27 had experienced borderline anxiety or depression, or both. Mood disturbance was positively correlated with adverse effects of treatment, particularly those affecting the gastrointestinal tract. Social adjustment was less affected, but failure to return to work, or a long delay in returning to work, and a persistent lack of interest in leisure activities gave cause for concern. These findings of substantial psychiatric and social morbidity in patients with Hodgkin's disease and non-Hodgkin's lymphoma prompted a prospective study of these patients to determine their nature and duration.

Adolescent↗
PubMed1987

Anogenital warts: epidemiology, treatment and association with cervical atypia.

In Northern Ireland in 1984 anogenital warts were diagnosed in 592 (352 male, 240 female) genitourinary medicine clinic attenders. Of these patients, 561 were heterosexual, 28 homosexual and three male bisexual. In the male patients 290 had penile warts, 67 meatal warts, 59 perianal warts, 25 anal canal warts and five rectal warts. In the female patients, 193 had vulval warts, 27 vaginal warts, 25 cervical warts, 107 perianal warts, 30 anal canal warts and one a rectal wart. Sexual partners were brought to the clinic by 345 patients and of these 93 male and 100 female partners had genital warts.The mean time from exposure to development of warts was 17 weeks SE +/- 1.5 (range 1 week - 12 months). As treatment, podophyllin 25% was used alone in 218 patients, and 132 were known to have had clearance of warts. At least one other sexually transmissible infection was found in 407 (69%) of patients. Cervical smears were taken in 164 women and were abnormal in 40 (24%). Cervical cytology was recorded in 89 regular sexual partners of male patients and was abnormal in 23 (26%).

Female↗
PubMed1979

Abortion today.

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Abortion, Legal↗
PubMed1973

Letter: Adoption.

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Adoption↗