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Urinary Tract Infections from a Multidrug-Resistant Clone of Escherichia coli
Twenty-two percent of women with E. coli urinary tract infections treated at a university health center in California had isolates that were resistant to trimethoprim–sulfamethoxazole. Half of these isolates were members of the same clonal group. This clonal group also accounted for over a third of the resistant E. coli isolates from women with urinary tract infections in Michigan and Minnesota.
A single, previously unrecognized clone of E. coli appears to be involved in a substantial fraction of community-acquired urinary tract infections in three locations in the United States. These surprising results challenge the conventional view of urinary tract infections as sporadic events. The spread of this clone could contribute to the increase in antibiotic resistance among E. coli urinary tract infections.
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B-Type Natriuretic Peptide in Acute Coronary Syndromes
Brain (B-type) natriuretic peptide is a neurohormone synthesized by ventricular myocardium and released in response to hemodynamic overload. In this study of 2525 patients with acute coronary syndromes, circulating levels of the peptide independently predicted the risk of death, new or recurrent myocardial infarction, or heart failure over a 10-month period.
This study shows not only that B-type natriuretic peptide is a useful prognostic biomarker in patients with acute coronary syndromes, but also that neurohormonal activation may be a unifying feature of patients at high risk for death after acute coronary syndromes.
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Pregnancy-Associated Plasma Protein A as a Marker of Acute Coronary Syndromes
Pregnancy-associated plasma protein A (PAPP-A) is a metalloproteinase, originally identified in the serum of pregnant women, that may be proatherosclerotic. In this study, abundant PAPP-A was identified in unstable coronary-artery plaques in patients who had died suddenly of cardiac causes, but not in stable plaques. Also, circulating PAPP-A levels were higher in patients with unstable angina or acute myocardial infarction than in patients with stable angina and normal controls.
PAPP-A, which has been used as a marker of Down's syndrome, may also be a useful marker of unstable coronary-artery plaques. If the results of this study are confirmed, PAPP-A may add to the diagnostic information provided by other markers of unstable coronary disease, such as creatine kinase MB, troponins I and T, and C-reactive protein.
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Polymorphisms of the  2-Adrenergic Receptor and Vascular Reactivity
In this study of normal subjects, two common polymorphisms of the  2-adrenergic receptor were found to influence vascular reactivity in response to 2-adrenergic agonists. The Arg16 polymorphism was associated with rapid agonist-mediated desensitization, whereas the Gln27 polymorphism was associated with enhanced agonist-mediated vasodilatation.
These findings advance our understanding of the genetic regulation of vascular responsiveness and could have implications for the pathogenesis of hypertension and racial differences in vascular responsiveness.
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Development of Type 1 Diabetes despite Severe Hereditary B-Cell Deficiency
The pathogenesis of type 1 diabetes, which results from immune-mediated destruction of pancreatic beta cells, has been debated. The role of T cells in autoimmune diabetes is widely accepted, yet whether B cells and autoantibodies have a role has been less clear. This report documents type 1 diabetes in a teenage boy who had no functional B cells because he had X-linked agammaglobulinemia.
This case report clearly demonstrates that B cells are not required for the development of type 1 diabetes and may explain why immunotherapies directed at B cells or autoantibodies may fail to prevent the destruction of beta cells in patients at risk.
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Advances in Immunology: Vaccines and Vaccination
According to a 1998 World Health Organization survey, diarrhea and acute respiratory tract infections, often due to viruses, kill 6 to 7 million children annually worldwide. Infection with the human immunodeficiency virus, malaria, and tuberculosis cause 7 to 8 million deaths annually. Vaccination is the most practical way of preventing these and other deadly infections. This review, part of the Immunology series, analyzes the available vaccines, explains why vaccines can be ineffective, and points to new forms of technology that promise not only improvements in existing vaccines but also new kinds of vaccines.
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