Publications

Considerable controversy and uncertainty have surrounded the biological function of the Human Immunodeficiency Virus (HIV)-1 nef gene product. Initial studies suggested that this early, nonstructural viral protein functioned as a negative regulatory factor; thus, it was proposed to play a role in establishing or maintaining viral latency. In contrast, studies in Simian Immunodeficiency Virus (SIV)mac-infected rhesus monkeys have suggested that Nef is not a negative factor but rather plays a central role in promoting high-level viral replication and is required for viral pathogenesis in vivo. We sought to define a tissue culture system that would approximate the in vivo setting for virus infection in order to assess the role of HIV-1 Nef in viral replication. We show that infection of mitogen-activated peripheral blood mononuclear cells (PBMC) with Nef+ HIV results in enhanced replication as evidenced by earlier gag p24 expression when compared with infections performed with nef mutant viruses. Moreover, when unstimulated freshly isolated PBMC are infected with Nef+ and Nef- viruses and then subsequently activated with mitogen, the Nef-induced difference in viral replication kinetics is even more pronounced, with the Nef- viruses requiring much more time in culture for appreciable growth. A positive effect of Nef on viral replication was also observed in primary macrophages infected with a recombinant of YU-2, a patient-derived molecular clone with macrophage tropism. These positive effects of Nef on viral replication are dependent on the initial multiplicity of infection (MOI), in that infections of unstimulated PBMC at low MOI are most dependent upon intact nef for subsequent viral growth. We now provide evidence that the Nef+ HIV is more infectious than Nef- HIV from both a tissue culture infectious dose analysis, and a single-cell HIV infection assay. In the latter case, we demonstrate that infection with equivalent doses of HIV based on virion-associated gag p24 yields five- to sixfold more infected cells if Nef+ viral stocks were used. Furthermore, we find that the differential infectivity is not dependent on CD4 down-regulation as Nef+ virus produced from transfected COS cells lacking CD4 is also more infectious. However, normalization of PBMC infections to equivalent infectivity between that of the Nef+ and Nef- viruses continues to reveal delayed viral replication in the absence of Nef, suggesting that secondary viral spread in PBMC is also enhanced in Nef+ infections. We demonstrate this directly by showing a 13-15-fold increase in infectivity of PBMC-derived Nef+ HIC.(ABSTRACT TRUNCATED AT 400 WORDS)

Transforming growth factor-beta 1 (TGF-beta 1) is generally considered to exert positive effects on the accumulation of extracellular matrices. These occur as the net result of enhanced matrix protein synthesis, diminished matrix metalloproteinase (MMP) synthesis, and augmented production of specific inhibitors, including the tissue inhibitor of metalloproteinases (TIMP-1). Given that glomerular TGF-beta 1 synthesis is induced by inflammation, the effects of this cytokine on synthesis of the 72-kd type IV collagenase and TIMP-1 by cultured human mesangial cells were evaluated. Concentrations of TGF-beta 1 of 5 ng/ml and above specifically stimulated the synthesis of the 72-kd type IV collagenase. This effect was independent of the stimulatory effect of TGF-beta 1 on TIMP-1 synthesis, which was maximal in a lower concentration range (0.1 to 1 ng/ml). Most significantly, the net effect at the higher concentrations of TGF-beta 1 was an excess of enzyme over the TIMP-1 inhibitor. Northern blot analysis of TGF-beta 1-stimulated human mesangial cells demonstrated a specific increase in the abundance of the 3.1 kb mRNA transcript encoding the 72-kd type IV collagenase, presumably mediated by a direct stimulation of 72-kd type IV collagenase mRNA transcription observed as early as 3 hours after exposure to TGF-beta 1. These studies were extended to an analysis of the expression of TGF-beta 1 and 72-kd type IV collagenase mRNAs in normal and nephritic rats. In normal animals, basal TGF-beta 1 and 72-kd type IV collagenase mRNA expression was observed in a strictly mesangial distribution. After induction of acute immune complex-mediated glomerulonephritis, there was a major increase in TGF-beta 1 and 72-kd type IV collagenase mRNA expression, which was strictly limited to the expanded, hypercellular mesangial compartment. Enhanced synthesis of the mesangial type IV collagenase in response to TGF-beta 1 released during glomerular inflammatory processes could have an important role in the extensive glomerular matrix remodeling that accompanies these disorders.

Methyl ethyl ketone is a common solvent but data on overdose in humans are scarce. We report a case of co-ingestion of methyl ethyl ketone together with methanol associated with a hyperosmolar coma without anion gap metabolic acidosis. Blood levels of methyl ethyl ketone and its metabolite, 2-butanol, indicated that this solvent did contribute approximately 20 mosm/L to an observed osmolar gap of 99 mosm/L. At the levels detected, methyl ethyl ketone may have inhibited methanol metabolism, contributing to the low serum formate (1.3 mmol/L) and normal anion gap despite a blood methanol of 67 mmol/L.

Although drugs are frequently detected when studied in trauma series, the association between specific trauma types (such as gun shot wound) and drug use complicates interpretation of such reports. We carried out a case control study of trauma deaths with drug detection matched by cause with non-drug detection trauma fatality controls. We studied 117 case and control pairs identified from medical examiner's records. By multiple logistic regression analysis, younger adult age (OR 3.1; 95% CI 1.5 to 6.1) and black race (OR 2.3; 95% CI 1.1 to 5.0) were both strongly associated with drug detection. In contrast, neither gender, intent (homicide, suicide or unintentional), primary trauma site, nor ethanol detection were significantly associated with drug detection. Our findings suggest that case mix variables should be considered when interpreting the drug use rates in trauma.

We reviewed the relationship between occupational respiratory medicine and the environmental health aspects of air pollution control. Although these fields share epidemiologic and toxicologic concerns, they collaborate infrequently. From an historical perspective, both occupational health and air pollution control efforts increased in response to the Industrial Revolution but only occasionally overlapped. Moreover, they were undermined by the belief in "bad air" as the cause of epidemic disease. In the twentieth century, occupational medicine and industrial hygiene professionals together addressed mass air pollution exposure incidents, but this period of interdisciplinary activity was brief. Later regulatory approaches, together with economic pressures, have tended to divide rather than integrate occupational and environmental health. Despite their differences, these disciplines are linked by common scientific challenges. Recent governmental and non-governmental efforts suggests that future efforts in occupational health and air pollution control may become better coordinated.