Considerable evidence indicates that intravenous drug users are emerging as the group at greatest risk for both acquiring and spreading human immunodeficiency virus (HIV) infection. Thus, all possible methods to control the spread of HIV infection in intravenous drug users should be explored. Key recommendations are that HIV antibody testing of intravenous drug users should be voluntary, because mandatory testing is counterproductive; free distribution of needles and syringes to intravenous drug users should occur only in carefully controlled circumstances to determine its effectiveness in decreasing infection rates; and drug-free and methadone maintenance treatment programs should be available on demand to all intravenous drug users as a means of reducing the spread of HIV infection. At present, the primary strategy for prevention must be education resulting in behavioral change. Education is currently the only definitive means for controlling the spread of HIV infection among intravenous drug users, their sex contacts, and to fetuses.

Advances in surgical and immunosuppressive techniques as well as increased public awareness have made organ transplantation a well-accepted therapy. To meet the increased need for transplantable organs, medical staff need to recognize which dying patients may be suitable organ donors and how to optimally maintain that donor. We present an overview of the absolute and relative contraindications to organ donation as well as a review of the problems that may be encountered when managing organ donors and how they can best be solved. These guidelines will help increase the number of suitable organ donors and optimize the condition of the transplanted organs.

New evidence shows that systemic and intrarenal hemodynamic abnormalities are major factors in the initiation and progression of diabetic nephropathy. Genetic predisposition to elevated systemic blood pressure may contribute to its development. Glomerular vasodilation and hyperfiltration, mediated in part by prostaglandins, may play a role in glomerular damage early in the course of diabetes, but clinical studies are limited. The development of more sensitive assays for albuminuria now allows early diagnosis of incipient nephropathy in the "microalbuminuria" phase. Treatment during this phase with antihypertensive agents, including angiotensin-converting enzyme inhibitors, or with dietary protein restriction, can decrease the degree of albuminuria, but data on their long-term effects on disease progression are limited. In hypertensive patients with established clinical diabetic nephropathy characterized by proteinuria in excess of 0.3 to 0.5 g/d, antihypertensive therapy has a major impact on delaying renal failure. Modalities that lower both systemic and intraglomerular pressure may be more beneficial in preserving renal function than those that primarily lower systemic pressure. Any therapeutic intervention should be monitored meticulously to establish its efficacy and safety in the individual patient. Therapy specifically directed against hemodynamic abnormalities throughout the course of diabetic renal disease may significantly delay and decrease the negative impact of this diabetic complication on survival and quality of life.

Voluntary screening for human immunodeficiency virus (HIV) infection may help prevent the spread of the HIV epidemic if persons who test positive alter behaviors that may transmit infection. Protecting persons from unknowingly being exposed to HIV infection must be balanced against respecting the autonomy of individuals being screened. Seropositive patients may feel a stigma and be subjected to discrimination if confidentiality of test results is breached. In patients without high-risk behaviors, the positive predictive value of HIV testing may be substantially increased if tests are done in reference laboratories and if further confirmatory tests are run on a second blood specimen. For persons with high-risk behaviors, HIV testing can be recommended to those who want to reduce uncertainty about their HIV status or whose medical care would change if they were seropositive. Health care workers can maximize benefits of screening and minimize harm by educating and counseling patients before HIV testing, discussing the confidentiality of HIV test results, urging patients to disclose positive test results to sex partners, and advising patients on how to reduce high-risk behaviors.

To familiarize the general internist with the unique features of pulmonary edema occurring in association with tocolytic therapy (drugs used to inhibit uterine contractions).

As the epidemic of the acquired immunodeficiency syndrome (AIDS) expands, the prevalence of the human immunodeficiency virus (HIV) infection in health care environments will increase and health care workers in many locations are likely to be at increased risk for exposure. The Fifth Annual Advances in Occupational Cancer Conference, held in December 1988 in San Francisco, addressed occupational HIV infection. Symposium participants concluded that the risk of HIV infection for health care workers is low but not zero. Implementation of universal blood and body fluid precautions was agreed to as an appropriate method of preventing exposure to HIV, especially for preventing needlestick accidents. Current standards for hospital waste disposal were judged to be adequate to prevent transmission of HIV, and confidential testing for HIV antibody in health care workers with follow-up counseling was recommended where indicated. It was also agreed that the risk of occupational exposure to HIV does not free health care workers from the responsibility to provide care to infected persons.

From our review of the epidemiologic and clinical literature, we have developed recommendations for using the serum cholesterol test as a component of strategies to prevent coronary heart disease in asymptomatic adults. Total cholesterol, high-density lipoprotein, and low-density lipoprotein levels are risk factors for coronary disease and early mortality in middle-aged men. Weaker evidence suggests that hypercholesterolemia increases the risk for coronary disease in women or elderly men, or that hypertriglyceridemia increases the risk in men or women. A reduction in cholesterol levels lowers the incidence of and the mortality from coronary disease in asymptomatic, hypercholesterolemic, middle-aged men, but has not been shown to reduce overall mortality. The efficacy of treatment in women and elderly persons has not been studied. Screening and treatment plans should be individualized; a 5-year period between tests is adequate for asymptomatic, low-risk men, whereas more frequent testing is appropriate for high-risk men. Screening is optional for women and elderly persons.

Increased neural inhibition appears to be an important component of the syndrome of hepatic encephalopathy. The pathways subserved by the gamma-aminobutyric acid (GABA)-benzodiazepine receptor complex are the principal inhibitory systems in the mammalian brain. Hyperpolarization of neural membranes is accomplished by an increase in transmembrane chloride flux through a GABA-gated chloride channel in the complex. The opening of the chloride channel is induced by the binding of GABA to its receptors, and it is potentiated by barbiturates or benzodiazepines that act at distinct recognition sites on the complex. Involvement of the GABA neurotransmitter system in hepatic encephalopathy is suggested by several findings in animal models of fulminant hepatic failure. For example, hepatic encephalopathy resembles encephalopathies induced by drugs (including benzodiazepines) that potentiate GABAergic neurotransmission. In addition, neurons from animals with hepatic encephalopathy show increased sensitivity to benzodiazepine and GABA receptor agonists. Moreover, these neurons are excited by benzodiazepine receptor antagonists at concentrations that do not affect control neurons. Also, elevated levels of a substance that inhibits radioligand binding to benzodiazepine receptors have been found in cerebrospinal fluid from animals with hepatic encephalopathy. Furthermore, manifestations of hepatic encephalopathy can be ameliorated by benzodiazepine receptor antagonists. The relevance of these findings to hepatic encephalopathy in human beings is supported by clinical observations showing that a benzodiazepine receptor antagonist can lessen the degree of hepatic encephalopathy. These findings suggest that an endogenous substance with benzodiazepine-like properties contributes to the neuropsychiatric manifestations of hepatic encephalopathy by augmenting GABAergic neurotransmission.

Because coronary angioplasty is being increasingly used as a treatment for coronary artery disease, the proper evaluation and management of patients after the procedure are important issues. Although coronary angioplasty is a complex technical procedure, the methods routinely used to evaluate its results have many shortcomings. Although the initial results of the procedure are assessed most commonly by the visual interpretation of video images and coronary angiograms, quantitative angiography, trans-stenotic pressure gradients, and coronary flow reserve measurements have also been used. In the period after coronary angioplasty, success can be evaluated by patients' clinical improvement in symptoms and their stress responses to various functional tests. The management of the patient during the first 24 hours after angioplasty should focus on the prevention, detection, and, if necessary, treatment of acute vessel closure. During the subsequent 6 months, the emphasis should shift to the evaluation of recurrent symptoms and prevention of restenosis. We discuss the methods used to assess the results of coronary angioplasty and suggest guidelines for managing patients after the procedure.