Publications

In this study, we present direct evidence for the binding of the inducible cellular protein, HIVEN86A, to a 12-bp element present in the IL-2R alpha promoter. This element shares significant sequence similarity with the NF-kappa B binding sites present in the HIV-1 and kappa immunoglobulin enhancers. Transient transfection studies indicate that this kappa B element is both necessary and sufficient to confer tax or mitogen inducibility to a heterologous promoter. As summarized schematically in Fig. 5, the findings suggest that the HIVEN86A protein may play a central role in the activation of cellular genes required for T-cell growth, specifically the IL-2R alpha gene. In addition, the induced HIVEN86A protein also binds to a similar sequence present in the HIV-1 LTR leading to enhanced viral gene expression and ultimately T-cell death. Thus, mitogen activation of the HIV-1 LTR appears to involve the same inducible transcription factor(s) that normally regulates IL-2R alpha gene expression and T-cell growth. These findings further underscore the importance of the state of T-cell activation in the regulation of HIV-1 replication. Our results also demonstrate that HIVEN86A is induced by the tax protein of HTLV-I. Thus, in HTLV-I infected cells, normally the tight control of the transient expression of the IL-2R alpha gene is lost. The constitutive high-level display of IL-2 receptors may play a role in leukemic transformation mediated by HTLV-I (ATL). Apparently by the same mechanism, the tax protein also activates the HIV-1 LTR through the induction of HIVEN86A.(ABSTRACT TRUNCATED AT 250 WORDS)

Removal of epithelium from mammalian tracheae has been shown to enhance responsiveness to a variety of contractile and relaxant agents. One of the most dramatic shifts reported has been for guinea pig tracheal tissue denuded of epithelium and treated with substance P. We investigated whether this shift in responsiveness was because of 1) removal of an epithelium-associated enzyme, neutral endopeptidase, which degrades substance P and 2) loss of an epithelium-derived noncyclooxygenase relaxant factor. Using a muscle bath preparation we performed concentration-response curves with substance P and acetylcholine on indomethacin-treated tissues with and without intact epithelium and with and without pretreatment with the neutral endopeptidase inhibitor, phosphoramidon. Epithelium removal potentiated the mean agonist concentration calculated to causes 30% of the maximal contractile response by 148-fold for substance P and by 7-fold for acetylcholine. Phosphoramidon potentiated the contractile response to substance P, but not to acetylcholine, by both the epithelium-intact and denuded tissues (P less than 0.05). However, the degree of enhancement by phosphoramidon was much greater in the intact tissues. With phosphoramidon treatment, therefore, the difference in responsiveness to substance P between the intact and denuded tissues was reduced from 148-fold to 18-fold. This effect of phosphoramidon suggests that the hyperresponsiveness to substance P of epithelium-denuded airway tissue is largely because of removal of neutral endopeptidase. Because all tissues were treated with indomethacin, the leftward shifts in substance P and in acetylcholine responsiveness induced by epithelium removal further suggest that an epithelium-derived noncyclooxygenase factor other than neutral endopeptidase also modulates the contractile response to substance P and to acetylcholine.

In the Negev region of Israel, I tested a model approach to occupational health planning. This model included components assessing exposures, measuring adverse health outcomes, and evaluating health services. I analyzed employment survey data, compiled an exposure data base, and carried out site visits covering 10,707 employees (over 50% of the regional industrial work force). Site visits identified exposure hazards of inorganic and organic dusts, heavy metals, chemicals, pesticides, and noise. I identified elevated relative regional injury rates by Standard Morbidity Ratios (SMRs) in a variety of industries, including sixfold increases for mining and non-metallic minerals manufacture (SMR 6.8, 99% CI 6.1-7.7). Review of biological monitoring data suggested deficiencies in pesticide and heavy metals surveillance. A survey of primary care clinics estimated 13,707 cases of occupational injury and illness untreated by existing occupational medical services. Based on these findings, I formulated regional occupational health planning goals, including targeting high-risk industries for increased preventive activities. This regional approach, combining multiple measures of occupational health status, can serve as a model for assessing local public health planning needs.

Administration of the allylbarbiturate secobarbital (SB) to phenobarbital-pretreated rats is known to result in structural and functional loss of hepatic cytochrome P-450 and generation of N-alkylated prosthetic heme derivatives. Isozyme-selective functional markers have led us to confirm P-450b as the isozyme selectively inactivated by the drug. In contrast to its inactivation by allylisopropylacetamide, such SB-inactivated P-450b is not amenable to structural and functional repair by exogenous heme, for reasons that remain unclear. In an effort to gain some insight, we have explored various possible mechanisms. In the course of these studies with rat liver microsomes enriched in P-450b as well as isolated purified P-450b, we have found that, along with prosthetic heme alkylation, a significant fraction of the hemoprotein also undergoes drug-mediated alkylation of the apocytochrome, presumably at the active site. Accordingly, an equimolar ratio of irreversibly bound drug to functionally inactive residual P-450b chromophore is observed after incubation of the purified isozyme with SB and NADPH. Thus, P-450b-mediated oxidative metabolism of SB appears to partition not only between prosthetic heme alkylation and epoxidation but apoprotein alkylation as well.