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Biomedical subjects

J A Hahn

Publications and source records attributed to J A Hahn.

At least 19 recordsLinked to original sources
PubMed1994

Microbiology of community-acquired bacterial pneumonia in persons with and at risk for human immunodeficiency virus type 1 infection. Implications for rational empiric antibiotic therapy.

BACKGROUND: Bacterial pneumonia is a very common cause of morbidity and mortality among persons with human immunodeficiency virus; however, the microbiologic characteristics (including antibiotic resistance) of bacterial pathogens causing community-acquired pneumonia in this population have not been well characterized or correlated with potentially predictive clinical presentation characteristics. METHODS: We conducted a retrospective cohort study of all adults known to have or to be at high risk for human immunodeficiency virus infection and hospitalized at San Francisco (Calif) General Hospital from May 1990 through April 1991, with a hospital discharge diagnosis of community-acquired bacterial pneumonia and for whom a medical records review confirmed that this diagnosis met a uniform case definition. RESULTS: Two hundred sixteen eligible patients had one or more hospital admissions meeting the case definition. One or more etiologic pathogens were definitively identified in 75% of cases, with Streptococcus pneumoniae, Haemophilus species, Staphylococcus aureus, and gram-negative bacilli most frequently identified. In patients who had a bacteriologic diagnosis made, 18.6%, 6.8%, and 4.3% had pneumonia caused by pathogens resistant to ampicillin sodium, cefuroxime sodium, or trimethoprim-sulfamethoxazole, respectively. One hundred percent of pathogens isolated were susceptible to ceftazidime. Anemia and use of antibacterial medication at the time of hospital admission were the only independent predictors of ampicillin and cefuroxime resistance. CONCLUSION: Nearly one fifth of human immunodeficiency virus-associated community-acquired bacterial pneumonias requiring hospitalization were caused by ampicillin-resistant pathogens, and presenting clinical characteristics did not consistently define a subset of patients at lower risk for resistance. In the absence of a diagnostic sputum Gram's stain and pending definitive microbiologic diagnosis, initial empiric therapy should be with a second- or third-generation cephalosporin or possibly trimethoprim-sulfamethoxazole.

AIDS-Related Opportunistic Infections↗
PubMed1994

HIV and tuberculosis infection in San Francisco's homeless adults. Prevalence and risk factors in a representative sample.

OBJECTIVE: To determine the prevalence and risk factors for human immunodeficiency virus (HIV) and tuberculosis (TB) infection and investigate the relationship between these two infections in homeless adults. DESIGN: Cross-sectional study. SETTING: Inner-city shelters and free meal programs. PARTICIPANTS: A representative sample of 1226 adults (> or = 18 years) were enrolled from community sites. MAIN OUTCOME MEASURES: Serum HIV-1 antibody status and tuberculin skin test reactivity. RESULTS: Human immunodeficiency virus seroprevalence was 8.5% (95% confidence interval [CI], 7.0% to 10.1%) and the prevalence of TB infection was 32% (95% CI, 30% to 37%). Nineteen percent of the HIV-seropositive subjects had positive tuberculin skin tests. Independent risk factors for HIV infection included younger age, black race, male homosexual contact, injection drug use, use of injection drugs in shooting galleries, and selling sex. Tuberculosis infection was associated with the duration of homelessness and living in crowded shelters or single-room-occupancy hotels. Injection drug use, a risk factor for HIV, was also a risk factor for TB, with a particularly strong association in women. No evidence of an association between TB and HIV infection was found, even after accounting for anergy. CONCLUSIONS: The homeless population in the United States should be considered a group at high risk for HIV infection and TB. Given the constellation of risk factors present, the high prevalence of infection, and lack of access to medical services, we anticipate that these communicable diseases in this population will represent a growing public health problem.

Adult↗
PubMed1994

Transmission of tuberculosis in New York City. An analysis by DNA fingerprinting and conventional epidemiologic methods.

BACKGROUND: The incidence of tuberculosis and drug resistance is increasing in the United States, but it is not clear how much of the increase is due to reactivation of latent infection and how much to recent transmission. METHODS: We performed DNA fingerprinting using restriction-fragment-length polymorphism (RFLP) analysis of at least one isolate from every patient with confirmed tuberculosis at a major hospital in the Bronx, New York, from December 1, 1989, through December 31, 1992. Medical records and census-tract data were reviewed for relevant clinical, social, and demographic data. RESULTS: Of 130 patients with tuberculosis, 104 adults (80 percent) had complete medical records and isolates whose DNA fingerprints could be evaluated. Isolates from 65 patients (62.5 percent) had unique RFLP patterns, whereas isolates from 39 patients (37.5 percent) had RFLP patterns that were identical to those of an isolate from at least 1 other study patient; the isolates in the latter group were classified into 12 clusters. Patients whose isolates were included in one of the clusters were inferred to have recently transmitted disease. Independent risk factors for having a clustered isolate included seropositivity for the human immunodeficiency virus (HIV) (odds ratio for Hispanic patients, 4.31; P = 0.02; for non-Hispanic patients, 3.12; P = 0.07), Hispanic ethnicity combined with HIV seronegativity (odds ratio, 5.13; P = 0.05), infection with drug-resistant tuberculosis (odds ratio, 4.52; P = 0.005), and younger age (odds ratio, 1.59; P = 0.02). Residence in sections of the Bronx with a median household income below $20,000 was also associated with having a clustered isolate (odds ratio, 3.22; P = 0.04). CONCLUSIONS: In the inner-city community we studied, recently transmitted tuberculosis accounts for approximately 40 percent of the incident cases and almost two thirds of drug-resistant cases. Recent transmission of tuberculosis, and not only reactivation of latent disease, contributes substantially to the increase in tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1993

Trends in Down's syndrome prevalence in California, 1983-1988.

Trends in the prevalence of Down's syndrome in livebirths were examined in California from 1983 to 1988, a time period when prenatal screening and subsequent termination of Down's syndrome pregnancies among women under 35 years of age was increasing. In the population-based ascertainment areas of the California Birth Defects Monitoring Program (CBDMP), 1058 infants with Down's syndrome were identified, giving a crude prevalence of 1.03 (95% confidence interval [CI]: 0.97, 1.09). The risk ratio for 1988 compared with 1983, after adjusting for maternal age and other confounders, was 0.98 (95% CI: 0.78, 1.23), showing that there was no change in livebirth prevalence over this period. The data were also examined for mothers under 35 years of age to determine whether increasing use of prenatal screening leading to termination masked an increase in prevalence. A modest increase was seen.

Abortion, Therapeutic↗
PubMed1992

Cost efficient sampling design for quality control of a birth defects registry.

Quality control studies of registries are frequently conducted. We employed a cost effective sampling scheme for assessing the quality of case identification and abstracting in one birth defects registry. The general sampling method was a stratified two-stage design, and the optimal sample size for each stratum was chosen to minimize cost, which was defined as time for data collection. The resulting sample sizes depended on the variability in the number of abstracts between and within data collection facilities, and the amount of time needed to complete each data collection step. The most time effective scheme was to visit several facilities each for a short period of time rather than fewer facilities for a longer period of time. Cost efficient sampling strategies, such as the method used here, can be applied to ensure precision in registry quality control analyses and other public health studies.

Congenital Abnormalities↗
PubMed1990

The blade implant.

Explore the source record for details and available documents.

Blade Implantation↗
PubMed1981

Studies of the renal vasoactive systems in hyporeninemic hypoaldosteronism.

Plasma renin activity, total renin, active renin, and aldosterone were measured as well as urinary prostaglandin E2 and kallikrein in a group of patients with hyperkalemia (6.1-7.7 mEq per liter) and hyporeninemic hypoaldosteronism. Plasma renin activity and aldosterone were low and the response was markedly blunted to upright posture, and furosemide. The rise in cortisol but not aldosterone was normal following ACTH stimulation. Active renin was depressed; however, total renin was normal. Urine PGE was variable including some low values, but the mean of the group was normal (p greater than 0.1). Urine kallikrein excretion was markedly diminished and undetectable in most cases. Fludrocortisone normalized potassium but minimally increased kallikrein in the patients. The possibility exists that kallikrein deficiency in these patients may underlie the inability to generate active renin.

Adrenocorticotropic Hormone↗
PubMed1978

Release of immunoassayable prostaglandin E by the human ischemic kidney.

Immunoassayable prostaglandin E concentration in renal venous plasma was measured in eight patients with renovascular hypertension. Two subjects with bilateral renal artery stenosis had similar concentrations from both renal veins. The six subjects with unilateral artery stenosis had greater concentration on the stenotic side in each case, suggesting that the human ischemic kidney produces increased amounts of prostaglandins.

Humans↗
PubMed1978

The Christian administrator in a secular society.

While government involvement with hospitals complicates an administrator's operating environment, much of what government and consumer advocates want is at least philosophically good. In the midst of conflicts between a secular society and the goals of church-related hospitals, Christian administrators must demonstrate integrity and would do well to see adversity as a challenge promoting greater strenghts for themselves and for their hospitals.

Christianity↗
PubMed1976

Ultrastructure of sickling and unsickling in time-lapse studies.

The denser subpopulation of erythrocytes from patients with sickle cell anaemia was deoxygenated to a pO2 of 4.7 kPa or reoxygenated to a pO2 of 12 kPa with a continuous-flow apparatus. Samples were collected into modified Karnovsky's fixative at intervals between 0.5 and 15 S. .The earliest event after deoxygenation was aggreagation of haemoglobin followed by the formation of fibres of 160-200 A diameter. The polymers were always randomly distributed in a loose network. A highly ordered, close packing of fibres characteristic of the nematic liquid crystal was not achieved within 15 S. Depolymerization involved a shortening of fibres followed by aggregation similar to that observed early in the polymerization process and prior to the return to the unperturbed state. Irreversibly sickled cells were the first to demonstrate polymers following deoxygenation and that last to lose polymers after reoxygenation. Polymerization of the haemoglobin preceded the appearnce of the sickled deformity of reversibly sickled cells and, following reoxygenation, the return to the discoid shape lagged behind the disappearance of polymers. These studies, carried out under physiologic conditions, have demonstrated intracellular changes during time intervals that correspond to the normal venous and arterial circulation that may contribute to the pathophysiology of sickling disorders.

Adolescent↗