Drug-induced hepatotoxicity

Tuberculosis in Africa: clinical presentation and management

In the last decade, sub-Saharan Africa has experienced an explosive increase in tuberculosis (TB) cases, largely as a result of the co-epidemic of human immunodeficiency virus (HIV) infection. This article reviews the essential background epidemiology of TB in sub-Saharan Africa. The clinical features and diagnostic problems of pulmonary/extrapulmonary TB in adults and children are discussed, particularly in relation to HIV infection. Different treatment regimens, their cost, adverse reactions, the ways in which HIV infection influences treatment response and the extent of drug resistance are reviewed. The recommended approaches to TB control in Africa, including methods used to prevent TB through Bacillus Calmette-Guerin and chemoprophylaxis are examined. The success achieved by good National TB Control Programmes in some African countries allows cautious optimism that this epidemic can be controlled.

A jaundiced farmer

A previously well farmer became deeply jaundiced after dipping sheep with organophosphate sheep dips. He had failed to wear adequate protective clothing and presumably absorbed toxic compounds through his skin. There is currently major interest in these compounds because of their protean clinical manifestations.

Evaluation of abnormal liver function tests

Although the liver can be affected in a wide range of disorders, the differential diagnosis of abnormal liver function tests can be substantially narrowed by a comprehensive history and physical examination and by the recognition of relatively distinct biochemical patterns of liver injury. Although referral to a specialist may be required for the performance of, for example, percutaneous liver biopsy and long-term management of chronic liver disease, a presumptive diagnosis can usually be made in the vast majority of patients who present to primary care physicians with abnormal liver function tests.

Metabolism of phenytoin by the gingiva of normal humans: the possible role of reactive metabolites of phenytoin in the initiation of gingival hyperplasia

Gingival hyperplasia is a well-known complication of therapy with cyclosporine, calcium channel blockers, and phenytoin. It is characterized by the presence of inflammation and a marked fibrotic response. The mechanism of this adverse reaction is unknown. We propose that it may be initiated by the metabolic activation of these drugs to form reactive metabolites. These then cause cellular injury and lead to the gingival hyperplasia. To evaluate this hypothesis we examined phenytoin metabolism and the cytochrome P450 contents of gingival tissues from 10 patients undergoing surgery for various periodontal conditions. We found that microsomes obtained from the gingiva show significant phenytoin hydroxylase activity as determined by the production of 5-(4'-hydroxyphenyl)-5-phenylhydantoin (HPPH) (range, 12.8 pmol HPPH/min.mg microsomal protein to 276.9 pmol HPPH/min.mg microsomal protein; rat control, 133.7 +/- 11.5 pmol HPPH/min.mg microsomal protein). We also found that CYP1A1, CYP1A2, CYP2C9, CYP2E1, and CYP3A4 were present in these microsomes. We detected no CYP2B6 or CYP2D6. We believe that these data support our hypothesis that the proliferative inflammation observed with drugs such as phenytoin, nifedipine, and cyclosporine may be initiated by the formation of reactive metabolites and that the formation of these metabolites may be catalyzed by one or more CYPs found in the gingiva. These metabolites may then cause cellular injury and induce a reactive inflammatory response, followed by fibroblastic proliferation. This proliferation leads to the excess collagen deposition observed with gingival hyperplasia.