Through the release of a variety of relaxing and contracting factors, including nitric oxide and endothelin-1, the endothelium exerts a complex paracrine influence on vascular smooth muscle cells. Dysfunction of these mechanisms for regulating tone may have relevance to various clinical entities, including hypertension, atherosclerosis, renal failure, and diabetes.
Several brain receptor systems can modulate food intake. Thus, in a new strategy against obesity, the patient takes submaximal doses of two drugs that act by differing mechanisms.
Penicillin-resistant pneumococcal strains continue to spread. Some strains are also resistant to other antibiotics, including the cephalosporins. Better utilization of the 23-valent pneumococcal vaccine, which covers the serotypes responsible for 90% of pneumococcal infections, is an important step in combating resistance.
The pathogen may proliferate years after seemingly successful treatment. The authors describe a classification system to evaluate both the disease and the patient's capacity to undergo the rigors of therapy. Two cases illustrate the clinical issues.
The persistent immune competence seen in a small percentage of HIV-infected individuals reflects the heterogeneity of both the virus and the host. Some HIV strains, for example, are more cytopathic than others. Host factors that promote longer survival lack "enhancing" antibodies, an appropriate balance of two crucial CD4+ cell subsets and their cytokines, and a strong CD8+ cell antiviral response.
For years, electrophysiologic testing was regarded as the best way to select effective pharmacologic therapy. But now it appears that Holter monitoring is just as accurate--as well as simpler, safer, and cheaper. Nevertheless, most patients eventually will need an electrophysiologic study because of the high rate of arrhythmia recurrence.
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