Polymicrobial brain abscess in a patient infected with human immunodeficiency virus.

Although intracranial mass lesions that occur as a result of infection have commonly been reported in patients infected with human immunodeficiency virus, polymicrobial pyogenic brain abscess has not been described in this setting. We report the first case of a patient with a polymicrobial brain abscess involving Streptococcus bovis, Fusobacterium necrophorum, Peptostreptococcus, and group G Streptococcus, and we review the relevant world literature.

Non-steroidal anti-inflammatory nephrotoxicity.

Non-steroidal anti-inflammatory drugs have a wide range of use in clinical practice because of their analgesic and anti-inflammatory properties. However, their potential nephrotoxicity has been noted. The case histories were studied, retrospectively, in 13 patients who were taking non-steroidal anti-inflammatory drugs as follows: four on fenoprofen (Nalfon), three on naproxen (Naprosyn), two on ibuprofen (Motrin), two on sulindac (Clinoril), one on tolmetin (Tolectin), and one on indomethacin (Indocin) and who exhibited abnormal urinalysis or a deterioration in renal function. Nine of the patients underwent renal biopsies, and eight of these biopsies were positive for interstitial nephritis. In addition to the presentation of additional cases of non-steroidal anti-inflammatory drug nephrotoxicity, a brief review of the current theories of the nephrotoxic mechanism is presented.

Effects of cholesterol and lipoproteins on endocytosis by a monocyte-like cell line.

The human monocyte/macrophage-like cell line U937 is a cholesterol auxotroph. Incubation of these cells in the growth medium in which delipidated fetal calf serum has been substituted for fetal calf serum depletes cellular cholesterol and inhibits growth. The cholesterol requirement of these cells for growth can be satisfied by human low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL), but not by high-density lipoprotein (HDL). U937 cells can bind and degrade LDL via a high-affinity site and this recognition is altered by acetylation of LDL. This indicates that these cells express relatively high LDL receptor activity and low levels of the acetyl-LDL receptor. The cells were used to study the role of cholesterol in lectin-mediated and fluid-phase endocytosis. Growth of the cells in the medium containing delipidated fetal calf serum results in impairment of both concanavalin A-mediated endocytosis of horseradish peroxidase and concanavalin A-independent endocytosis of Lucifer Yellow. Supplementation of the medium with cholesterol prevents cellular cholesterol depletion, supports growth and stimulates Lucifer Yellow endocytosis but fails to restore horseradish peroxidase endocytosis. However, if the cells are incubated in the presence of no less than 40 micrograms LDL protein/ml to maintain normal cell cholesterol levels, concanavalin A-mediated endocytosis of horseradish peroxidase is activated. The effect of LDL is specific since neither VLDL nor HDL3 at the same protein concentration activates horseradish peroxidase uptake by the cells. Furthermore, the activation of endocytosis by LDL is not inhibited by the inclusion of heparin or acetylation of the LDL indicating that binding of LDL to the LDL receptor is not required for these effects. The mediation of activation of horseradish peroxidase endocytosis by the lectin is presumed to involve binding of LDL to concanavalin A associated with the cell surface which in turn stimulates horseradish peroxidase binding and uptake by adsorptive endocytosis. The rate of fluid endocytosis and endosome formation seems to depend on cellular cholesterol content presumably because cholesterol is involved in maintaining the appropriate plasma membrane structure and fluidity.