Carlos Vaamonde

Transposon mutagenesis provides a direct selection for mutants and is an extremely powerful technique to analyze genetic functions in a variety of prokaryotes. Transposon mutagenesis of Mycobacterium tuberculosis has been limited in part because of the inefficiency of the delivery systems. This report describes the development of conditionally replicating shuttle phasmids from the mycobacteriophages D29 and TM4 that enable efficient delivery of transposons into both fast- and slow-growing mycobacteria. These shuttle phasmids consist of an Escherichia coli cosmid vector containing either a mini-Tn10(kan) or Tn5367 inserted into a nonessential region of the phage genome. Thermosensitive mutations were created in the mycobacteriophage genome that allow replication at 30 degrees C but not at 37 degrees C (TM4) or 38.5 degrees C (D29). Infection of mycobacteria at the nonpermissive temperature results in highly efficient transposon delivery to the entire population of mycobacterial cells. Transposition of mini-Tn10(kan) occurred in a site-specific fashion in M. smegmatis whereas Tn5367 transposed apparently randomly in M. phlei, Bacille Calmette-Guérin (BCG), and M. tuberculosis. Sequence analysis of the M. tuberculosis and BCG chromosomal regions adjacent to Tn5367 insertions, in combination with M. tuberculosis genomic sequence and physical map data, indicates that the transpositions have occurred randomly in diverse genes in every quadrant of the genome. Using this system, it has been readily possible to generate libraries containing thousands of independent mutants of M. phlei, BCG, and M. tuberculosis.

To evaluate risk factors for osteonecrosis in human immunodeficiency virus (HIV)-infected patients, demographic and clinical characteristics of case patients (n=17) and control patients (n=34) matched on initial clinic visit date, length of follow-up, and baseline CD4 cell count were compared. Case patients were more likely to have received corticosteroids (47.1% vs. 8.8%; matched odds ratio [OR], 13.1; 95% confidence interval [CI], 1.6-106), to have had an increase in CD4 cell count from nadir >0.050 x 10(9) cells/L (64.7% vs. 35.3%; OR, 4.9; 95% CI, 1.0-24), and to have had Pneumocystis carinii pneumonia (52.9% vs. 11.8%; OR, 7.6; 95% CI, 1.6-36). Use of protease inhibitors and history of other opportunistic infections did not significantly differ. In multivariate analysis, use of corticosteroids remained significantly associated with osteonecrosis, independently of HIV disease stage and protease inhibitor therapy. Corticosteroid use is an important risk factor for osteonecrosis, but its pathogenesis is likely multifactorial.

Effective antiretroviral therapy initially resulted in large decreases in hospitalization rates of HIV-infected patients. The goal of this study was to determine whether these gains were being maintained in 2001. A cross-sectional study of hospital admission characteristics during four time periods was performed. All patients receiving care at the HIV clinics of New York Presbyterian Hospital-Cornell Medical Center (NYPH) in New York City were included. In 1995, 883 outpatients were receiving care for HIV infection at NYPH; this increased to 1990 outpatients by 2001. Demographic and laboratory information was obtained for these outpatients, and diagnoses were recorded for all patients requiring hospitalization on at NYPH during the time periods January 1 through June 30, in 1995, 1997, 1999, and 2001. The incidence of hospital admission declined in all four time periods: 1995 (95 per 100 patient-years [pt-yr]), 1997 (48 per 100 pt-yr), 1999 (38 per 100 pt-yr, p < 0.05), and 2001 (25 per 100 pt-yr). The incidence of bacterial pneumonia and opportunistic infections (OIs) decreased in all four time periods. The median hospitalization were CD4(+) cell count for outpatients increased from 231 (1995) to 364 (2001). Important predictors of hospitalization were CD4(+) < 200, and IVDU as an HIV risk factor. Since 1995 and the introduction of highly active antiretroviral therapy, continuing increases in CD4(+) cell counts of outpatients has been reflected in persistent declines in hospitalization rates. Large decreases in OIs and pneumonia have been minimally offset by stable rates of hospital admissions for diagnoses such as hepatitis, cirrhosis, and cellulitis.

BACKGROUND: Diabetes mellitus (DM) is more prevalent among patients with HIV infection. Besides protease inhibitors (PIs), other factors may contribute to the development of DM. OBJECTIVE: To assess characteristics associated with the development of DM in HIV-infected persons. METHODS: We conducted a case-control study in an urban HIV clinic among patients with incident DM (49 cases) matched to 2 controls (n = 98) on age +/-5 years, race, sex, and length of clinic follow-up. There was a second set of unmatched controls (n = 196). RESULTS: Compared with matched controls, case patients had higher mean body mass index (BMI; 30.0 vs. 25.3 kg/m, matched odds ratio [OR] = 1.20; P < 0.001), higher alanine aminotransferase (ALT; 66 vs. 44 U/L, OR = 1.12 per 10 U/L; P = 0.013), and stronger family history of DM (50% vs. 29%, OR = 3.30; P = 0.009). Hepatitic C virus coinfection and PI use were not significant factors. In unmatched controls, there was no significant difference in age, sex, or ethnicity. In multivariate analyses, BMI (OR = 1.13 per kg/m; P = 0.012), family history (OR = 5.55; P = 0.014), and ALT (OR = 1.16; P = 0.012) were associated with DM. CONCLUSION: These findings suggest a complex interaction among genetic factors, body composition, and liver injury in the pathogenesis of DM in HIV-infected patients.