Differential divalent cation requirements uncouple the assembly and catalytic reactions of human immunodeficiency virus type 1 integrase

Previous in vitro analyses have shown that the human immunodeficiency virus type 1 (HIV-1) integrase uses either manganese or magnesium to assemble as a stable complex on the donor substrate and to catalyze strand transfer. We now demonstrate that subsequent to assembly, catalysis of both 3' end processing and strand transfer requires a divalent cation cofactor and that the divalent cation requirements for assembly and catalysis can be functionally distinguished based on the ability to utilize calcium and cobalt, respectively. The different divalent cation requirements manifest by these processes are exploited to uncouple assembly and catalysis, thus staging the reaction. Staged 3' end processing and strand transfer assays are then used in conjunction with exonuclease III protection analysis to investigate the effects of integrase inhibitors on each step in the reaction. Analysis of a series of related inhibitors demonstrates that these types of compounds affect assembly and not either catalytic process, therefore reconciling the apparent disparate results obtained for such inhibitors in assays using isolated preintegration complexes. These studies provide evidence for a distinct role of the divalent cation cofactor in assembly and catalysis and have implications for both the identification and characterization of integrase inhibitors.     

A novel cyclic adenosine monophosphate analog induces hypercalcemia via production of 1,25-dihydroxyvitamin D in patients with solid tumors

The treatment of cancer patients with conventional chemotherapy is sometimes associated with severe systemic toxicity and only a minimal survival benefit. Because of this, new less toxic and more efficacious treatments have been sought. 8-Chloro-cAMP (8-Cl-cAMP) is one of a new generation of anticancer drugs that act at the level of signal transduction. In preclinical models, 8-Cl-cAMP modulates protein kinase A (PKA) leading to growth inhibition and increased differentiation of cancer cells. 8-Cl-cAMP was given to 16 patients with advanced cancer as an infusion via an indwelling subclavian venous catheter. We showed that 8-Cl-cAMP had a parathyroid hormone-like effect leading to increased synthesis of renal 1,25-dihydroxyvitamin D [up to 14 times the baseline value, median 3.6 times; P = 0.00001 (Student's paired t test)]. This produced the dose-limiting toxicity of reversible hypercalcemia that could not be controlled by the administration of either pamidronate or dexamethasone. The treatment was otherwise well tolerated, and other cAMP-dependent pathways (cortisol and TSH) were not affected, emphasizing the marked differences between organs in their sensitivity to this cAMP analog. Our results have shown that 8-Cl-cAMP is biologically active, and it is feasible that if the hypercalcemia can be controlled, then this drug may have a role as a single agent, or as a short infusion between cycles of chemotherapy.     

Synthesis and Estimation of Some Surface-Active Compounds Derived from Fused Pyridine as Corrosion Inhibitors for Aluminum in Hydrochloric Acid Solutions

Protection of Metals and Physical Chemistry of Surfaces - Three nonionic surfactants molecules (NS) derived from a fused pyridine characterized by IR and 1HNMR spectra were synthesized and examined...     

Aciduric, pH-Elevating Bacillus which Cause Noneffervescent Spoilage of Underprocessed Tomatoes

In the preliminary phase of this study, a selective isolation medium was developed. Using the new medium, 24 strains of Bacillus Spp. that elevate tomato juice pH were isolated from garden soil or natural vegetative materials. Two jars of home-canned, water-bathed tomatoes contained sporeformers which produced noneffervescent spoilage. All strains were morphologically and physiologically different from 2 flat-sour strains of B. coagulans and B. licheniformis strains, but similar to a previous isolate from home-canned, spoiled green beans that elevated pH. The new medium may have future applications in isolation and enumeration of other acidurics including yeast-like microorganisms.     

Fluorimetric Nerve Gas Sensing Based on Pyrene Imines Incorporated into Films and Sub‐Micrometer Fibers

The chemical sensing of nerve gas agents has become an increasingly important goal due to the 1995 terrorist attack in a Tokyo subway as well as national security concerns in regard to world affairs. Chemical detection needs to be sensitive and selective while being facile, portable, and timely. In this paper, a sensing approach using a pyrene imine molecule is presented that is fluorimetric in response. The detection of a chloro‐Sarin surrogate is measured at 5 ppmv in less than 1 second and is highly selective towards halogenated organophosphates. The pyrene imine molecule is incorporated into polystyrene films as well as micrometer and sub‐micrometer fibers. Using both a direct drawing approach and electrospinning, micrometer and nanofibers can be easily manufactured. Applications for functional sensing micrometer and nanofibers are envisioned for optical devices and photonics in addition to solution and airflow sensing devices.     

Evolution of the arthropod prophenoloxidase/hexamerin protein family

PURPOSE: Because intraperitoneal (i.p.) therapy may provide a therapeutic advantage and because hyperthermia enhances carboplatin (CBDCA) cytotoxicity, we evaluated the feasibility, toxicity, and pharmacokinetics of CBDCA given via continuous hyperthermic peritoneal perfusion (CHPP) in patients with small-volume residual ovarian cancer. Patients and METHODS: Six patients underwent optimal cytoreductive procedures (residual disease < or =5 mm) as initial treatment of stages II and III epithelial ovarian adenocarcinoma. All patients received a 90-min CHPP at a CBDCA dose of 800-1200 mg/m2, with the perfusate being recirculated rapidly from a reservoir through a heat exchanger, resulting in i.p. temperatures of 41-43 degrees C. Plasma, perfusate, and urine samples were collected and platinum was quantified by flameless atomic absorption spectrophotometry. RESULTS: At no time did any patient's core temperature exceed 40 degrees C. Peak perfusate platinum concentrations were 8- to 15-fold higher than peak ultrafilterable plasma concentrations. The permeability-area product was extremely high and variable (14-90 ml/min), resulting in a regional advantage of 1.9-5.3. The percentage of the dose absorbed ranged widely from 27% to 77%. Dose-limiting hematologic toxicity was observed at a dose of 1200 mg/m2 and this was associated with a CBDCA AUC in plasma of 11 mg min ml(-1). CONCLUSION: CHPP with CBDCA was safely given to three patients at a dose of 800 mg/m2, and dose-limiting hematologic toxicities observed at 1200 mg/m2, correlated with the plasma CBDCA exposure established when lower doses of CBDCA are given systemically. The pharmacokinetic data are consistent with the expected effect of vigorous mixing on the exposed peritoneal surface area. Variable drug absorption and clearance make the prediction of systemic exposure highly uncertain. These findings may have important implications for novel therapies given i.p.     

Transjugular intrahepatic portosystemic shunt (TIPS) for variceal bleeding in portal hypertension: comparison of emergency and elective interventions

Nonsurgical reduction of portal hypertension by transjugular intrahepatic portosystemic shunt (TIPS) is widely used for prevention of variceal rebleeding (elective TIPS). Information is limited about the value of emergency TIPS for acute variceal bleeding unresponsive to endoscopic and drug therapy. The aim of the present study was therefore to determine whether the effects and complications differ between emergency and elective TIPS in patients with cirrhosis of the liver. TIPS was performed in 11 patients with acute variceal bleeding unresponsive to endoscopic treatment and 22 patients in stable condition after an episode of variceal bleeding. Clinical examination, blood sampling, Doppler sonography of TIPS flow, and upper gastrointestinal endoscopy were performed at days 1, 7, and 30 and at three-month intervals after TIPS. Mean follow-up was 549 (1-987) days. Bleeding was controlled by emergency TIPS in 10/11 patients. Probability of survival was not different after emergency and elective TIPS (0.73 vs 0.84 at one year). Early rebleeding (< or =2 weeks) occurred more often after emergency TIPS (3/11 vs 0/22 patients; P = 0.03), but there was no significant difference in late rebleeding. Occlusion of TIPS was more frequent after emergency TIPS. Occurrence of TIPS stenoses was identical in both groups (4/11 vs 8/22). De novo or deterioration of preexisting hepatic encephalopathy was similar (18% vs 24%; NS). It is concluded that TIPS is effective for control of acute variceal bleeding unresponsive to endoscopic and drug treatment. Early rebleeding and stent occlusion occurred more often after emergency TIPS. Late rebleeding, complications, and long-term survival did not differ from elective TIPS.