Industrial fires and explosions due to electrostatic ignition

Static electricity is a frequent source of fires and explosions in industry. A variety of operations may generate static electricity leading to such fires and explosions. This requires adequate preventive and protective measures against this hazard. The present paper describes the theory and mechanism of electrostatic sparking, parameters needed to assess the respective hazard in a plant, safety measures to combat electrostatic problems, common operations where such problems exist and measures to eliminate or mitigate these problems.     

Enhanced biosynthesis of extracellular matrix proteins and TGF-beta 1 by polyinosinic-polycytidylic acid during cutaneous wound healing in vivo

OBJECTIVES: We sought to determine the utility of left ventricular expansion velocities in differentiating constrictive pericarditis from restrictive cardiomyopathy. BACKGROUND: Several studies have shown that left ventricular diastolic expansion is influenced by the elastic recoil forces of the myocardium. These forces are affected by intrinsic myocardial disease but should be preserved when diastole is impaired as a result of extrinsic causes. METHODS: Using Doppler tissue imaging, we measured peak early velocity of longitudinal axis expansion (Ea) in 8 patients with constrictive pericarditis, 7 patients with restriction and 15 normal volunteers. Transmitral early (E) and late (A) Doppler flow velocities, left ventricular systolic and diastolic volumes, ejection fraction and mitral annular M-mode displacement were also compared between the groups. RESULTS: The Ea value was significantly higher in normal subjects (14.5 +/- 4.7 cm/s [mean +/- SD]) and in patients with constriction (14.8 +/- 4.8 cm/s) than in those with restriction (5.1 +/- 1.4 cm/s, p < 0.001 constriction vs. restriction). There was weak correlation between Ea and the extent of annular displacement (r = 0.55, p = 0.004) and the E/A ratio (r = 0.44, p = 0.03). There was no correlation between Ea and E (r = 0.33, p = 0.07) or ejection fraction (r = 0.21, p = 0.26). By multivariate analysis, Ea was the best variable for differentiating constriction from restriction. CONCLUSIONS: Our study indicates that longitudinal axis expansion velocities are markedly reduced in patients with restrictive cardiomyopathy. The poor correlation found with transvalvular flow velocities suggests that Ea may be relatively preload independent. The measurement of longitudinal axis expansion velocities provides a clinically useful distinction between constrictive pericarditis and restrictive cardiomyopathy and may prove to be valuable in the study of diastolic function.     

Thymidylate synthase is localized to the nuclear periphery in the yeast Saccharomyces cerevisiae

To date, the organization of DNA precursor synthesis within eukaryotic cells remains unresolved. Previous studies have suggested the existence of a multienzyme complex that is responsible for DNA precursor synthesis and is associated with sites of replication within the nucleus. Contrasting this, other studies have proposed that DNA precursor synthesis occurs outside the nucleus. To further these studies, we have addressed the location where thymidylate synthase resides in yeast. Subcellular fractionation experiments indicate thymidylate synthase is associated with purified nuclei. Consistent with this, immunofluorescence analysis suggests that thymidylate synthase is situated at the nuclear periphery.     

Insights into Src kinase functions: structural comparisons

Recent structures of Src tyrosine kinases reveal complex mechanisms for regulation of enzymatic activity. The regulatory SH3 and SH2 domains bind to the back of the catalytic kinase domain via a linker region that joins the SH2 domain to the catalytic domain. Members of a subgroup of the Src kinase family show distinct features in this linker and in the loops that interact with it. Hydrophobicity of key residues in this region is important for intramolecular regulation. The kinases Abl, Btk and Csk seem to have the same molecular architecture as Src. Structural comparisons between serine/threonine and tyrosine kinases indicate a specific twisting mechanism involving the N- and C-terminal lobes of the catalytic domain. This motion could provide insights into the various mechanisms used to regulate kinase activity.     

Neuromuscular effects of rocuronium during sevoflurane, isoflurane, and intravenous anesthesia

The potency and time course of action of rocuronium were studied in patients anesthetized with 66% nitrous oxide in oxygen and 1.5 minimum alveolar anesthetic concentration of sevoflurane or isoflurane, or a propofol infusion. Potency was estimated by using the single-bolus technique. Neuromuscular block was measured by stimulation of the ulnar nerve and by recording the force of contraction of the adductor pollicis muscle. The mean (95% confidence limits) of the 50% and 95% effective doses were estimated tobe 142 (129-157) and 265 (233-301) microg/ kg, 165 (146-187) and 324 (265-396) microg/kg, and 183 (163-207) and 398 (316-502) microg/kg during sevoflurane, isoflurane, and propofol anesthesia, respectively (P < 0.05 for sevoflurane versus propofol). The mean +/- SD times to onset of maximal block after rocuronium 0.6 mg/kg were 0.96 +/- 0.16, 0.90 +/- 0.16, and 1.02 +/- 0.15 min during sevoflurane, isoflurane, and propofol anesthesia, respectively. The respective times to recovery of the first response in the train-of-four (TOF) stimulation (T1) to 25% and 90% were 45 +/- 13.1 and 83 +/- 29.3 min, 35 +/- 6.1 and 56 +/- 15.9 min, and 35 +/- 9.2 and 55 +/- 19.4 min. The times to recovery of the TOF ratio to 0.8 were 103 +/- 30.7, 69 +/- 20.4, and 62 +/- 21.1 min, and the 25%-75% recovery indices were 26 +/- 11.7, 12 +/- 5.0, and 14 +/- 6.9 min, respectively. There were no differences among groups in the times for onset of action or to recovery of T1 to 25%. However, the times for recovery of T1 to 90%, TOF ratio to 0.8, and recovery index in the sevoflurane group were all significantly longer compared with the other two groups (P < 0.05, < 0.01, and < 0.01, respectively). We conclude that the effects of rocuronium, especially duration of action, are significantly enhanced during sevoflurane compared with isoflurane and propofol anesthesia. IMPLICATIONS: In routine clinical use, the effects of rocuronium are enhanced by sevoflurane, in comparison with isoflurane and propofol anesthesia, and the recovery is slower. Particular attention should be paid to monitoring of neuromuscular block during sevoflurane anesthesia.     

Acute hepatic allograft rejection: incidence, risk factors, and impact on outcome

Hepatic allograft rejection remains an important problem following liver transplantation, and, indeed, complications related to the administration of immunosuppressive therapy remain a predominant cause of posttransplantation morbidity and mortality. The Liver Transplantation Database (LTD) was used to study a cohort of 762 consecutive adult liver transplantation recipients and determined the incidence, timing, and risk factors for acute rejection. We also evaluated the impact of histological severity of rejection on the need for additional immunosuppressive therapy and on patient and graft survival. Four hundred ninety (64%) of the 762 adult liver transplantation recipients developed at least one episode of rejection during a median follow-up period of 1,042 days (range, 336-1,896 days), most of which occurred during the first 6 weeks after transplantation. Multivariate analysis revealed that recipient age, serum creatinine, aspartate transaminase (AST) level, presence of edema, donor/recipient HLA-DR mismatch, cold ischemic time, and donor age were independently associated with the time to acute rejection. An interesting observation was that the histological severity of rejection was an important prognosticator: the use of antilymphocyte preparations was higher, and the time to death or retransplantation was shorter, for patients with severe rejection. Findings from this study will assist in decision-making for the use of immunosuppressive regimens and call into question whether complete elimination of all rejection or alloreactivity is a desirable goal in liver transplantation.