In vitro andin vivo effects of piroxicam on rat polymorphonuclear responsiveness after induction of two acute non-specific inflammatory reactions

The effect of piroxicam on rat polymorphonuclear leucocytes (PMN) has been studiedin vitro andin vivo after the induction of two acute, non specific inflammatory reactions (pleurisies induced by calcium pyrophosphate crystals (CaPP) or isologous serum).An inhibition of chemotaxis by piroxicam has been demonstrated by two techniques, the filter and agarose assaysin vivo andin vitro. An inhibition of random cell migration has been observed only at the higher drug concentration using agarose assay with CaPP-elicited cells.Piroxicam also inhibited superoxide anion generation and O₂ consumption of CaPP- and serum-elicited cells.These findings suggest that piroxicam may have a direct effect on PMN responses and that this activity could, at least in part, contribute to its anti-inflammatory properties.     

Blood Cultures Positive for Coagulase-Negative Staphylococci: Antisepsis,Pseudobacteremia, and Therapy of Patients

A blood culture cohort study investigating issues related to isolation of coagulase-negative staphylococci (CoNS) and other skin microflora is reported. Data were collected over 12 weeks to determine the incidence of significant CoNS bacteremia versus that of pseudobacteremia (contaminants) and to evaluate drug therapy in patients with cultures positive for CoNS. In addition, the effectiveness of 0.2% chlorine peroxide as a bactericidal disinfectant was compared to that of 10% providone iodine. A total of 3,276 cultures of blood from 1,433 patients were evaluated in the study. Eighty-nine cultures were positive for skin flora, with 81 of 89 (91%) involving CoNS. The incidence of significant CoNS bacteremia was 20 of 81 (24.7%), that of indeterminate bacteremia was 10 of 81 (12.3%), and that of contamination was 59 of 81 (72.8%). The incidence of significant bacteremia involving CoNS was double the 10 to 12% rate based on previous estimations at our institutions. In tests with the two bactericidal disinfectants, 22 of 1,639 cultures (1.3%) in the chlorine peroxide group versus 37 of 1,637 (2.3%) in the providone iodine group were considered contaminated (P = 0.065). Rates of contamination for venipuncture versus catheter collection were not significantly different (P = 0.46). The overall contamination rate was 59 of 3,276 (1.8%), which is consistent with the lower end of published quality assurance benchmark standards. The low rate was believed to be due to the professional phlebotomy staff in our institutions. There was excellent agreement between retrospective analysis by reviewers, when formal criteria were used, and the attending physicians’ intuitive clinical impressions in the classification of significant bloodstream infections (100% agreement) or contamination (95% agreement). However, physicians still used antimicrobial agents to treat nearly one-half of the patients with contaminated blood cultures, with vancomycin being misused in 34% of patients. In addition, 10% of patients with significant bacteremia were treated with inappropriate agents. There were no significant adverse events or prolonged hospital stays due to the unnecessary use of vancomycin; however, the additional costs of treating patients whose cultures contained CoNS contaminants was estimated to be $1,000 per patient. Measures to limit the unnecessary use of vancomycin (and other agents) are important.Coagulase-negative staphylococci (CoNS), the most frequent blood culture isolates, are predominantly blood culture contaminants, but they are also a significant cause of bacteremia (2–5, 7, 9, 13). Institution-specific contamination rates vary from 2 to more than 6% (3, 5, 23, 26, 27). In the past 5 years, estimated contamination rates at our hospitals ranged from 2.5 to 3.5%. During this period, CoNS accounted for 45 to 60% of total blood isolates, and we estimated, using laboratory criteria, that 10 to 12% of CoNS isolates from blood were implicated in significant bloodstream infections. A relatively large proportion of the patient population with presumed false-positive blood cultures due to contaminants (pseudobacteremia) were treated with antimicrobial agents, in particular, vancomycin.Clinical and microbiologic guidelines for the differentiation of true bacteremia from pseudobacteremia or contamination have been published (5, 13, 15). Suggested laboratory criteria for true bacteremia include growth within 48 h and multiple blood cultures positive for the same organism. In contrast, increased duration of time before positivity, polymicrobial growth of skin organisms, or growth during antibiotic treatment suggest contamination. Others recommended that the addition of clinical guidelines is essential for the appropriate classification of bacteremia (4, 8, 9, 15, 18).We conducted a cohort study to evaluate clinical and laboratory data for adult patients with blood cultures positive for CoNS. The study was done at two tertiary-care teaching centers, Deaconess Medical Center (DMC) and Sacred Heart Medical Center (SHMC), with a combined capacity of 900 beds. We examined problems associated with false-positive bacteremia and determined the incidence of significant bacteremia. Our goal was to make recommendations to improve clinicians’ ability to recognize the significance of potentially contaminating organisms and to evaluate treatment given to patients with CoNS-positive blood cultures. To attempt to minimize contamination, we evaluated the nontoxic, antiseptic and disinfectant chlorine peroxide in comparison to a standard disinfectant.(This work was previously presented in abstract form at the 96th General Meeting of the American Society for Microbiology, New Orleans, La., 19 to 23 May 1996 [24a].)     

Cloning and expression of surface antigens from occult chronic hepatitis B virus infections and their recognition by commercial detection assays

Occult hepatitis B virus (HBV) infections show little or no serological markers of viral infection, including the absence of hepatitis B surface antigen (HBsAg) which is the main marker of ongoing HBV infection. Such infections can be important in the context of blood and/or organ donations. To study whether mutations contribute to HBsAg seronegativity, S gene sequences from such patients were amplified and cloned. Sequencing revealed 12 clones from seven different patients which contained potentially important mutations. The sequences were subcloned into an expression vector and mutant HBsAgs were expressed in cell culture. The capacity of three HBsAg detection assays to recognise the mutant HBsAgs was studied. Three categories were found: mutant HBsAgs that are not recognised by the assays, those that are recognised as well as wild-type (WT) antigen and an intermediate category where detection of the mutant HBsAgs is reduced with respect to WT. Most of the isolates fall into the second category. Mutations can therefore contribute to HBsAg seronegativity in occult HBV infections, but in most cases the explanation is probably the low level of viral replication.     

Predictive value of early HCV RNA quantitation for sustained response in nonresponders receiving daily interferon and ribavirin therapy

The prognostic value of early hepatitis C virus (HCV)-RNA load was evaluated among nonresponder patients to previous interferon (IFN) therapy treated with daily IFN and ribavirin. One hundred-six nonresponders (83 men), mean age 44.8 +/- 11 years, were treated with IFN-alpha 2b 3 MU/day for 24 weeks, followed by 3 MU x 3/week for 24 weeks plus ribavirin 1-1.2 g/day for 48 weeks. HCV RNA was quantified by Versant HCV RNA 3.0 assay (Bayer). The predictive values of the baseline and the change in viral load at week 1, 4, and 12 for sustained virological responses were analyzed using receiver operating characteristic (ROC) curves, as well as predictive values of >2 log(10) drop from baseline by weeks 1, 4, and 12 in combination with undetectable HCV RNA for sustained virological response. Thirty-two patients (30.2%) were sustained virological responders. The highest area under the curve was obtained at week 4. The unquantifiable HCV RNA level, in combination with at least a 2 log(10) drop in viral load by week 4 and week 12, had a negative predictive value of 96% and 97%, respectively. Nonresponse can be predicted as early as week 4 or week 12 in nonresponders treated with daily IFN and ribavirin.     

Effect of rat soleus muscle overload on neuromuscular transmission efficacy during continuous and intermittent activation

Increased neuromuscular activity is known to provoke morphological and functional adaptations at the neuromuscular synapse. Most of these changes have been documented following endurance exercise training programmes. In this study, the effect of rat soleus muscle overload produced by tenotomy plus voluntary wheel-cage activity on neuromuscular transmission efficacy was investigated. The overload protocol increased miniature endplate potential (MEPP) and endplate potential (EPP) amplitudes by 17 and 19%, respectively (both P < 0.01), and increased MEPP frequency by 86% (P < 0.01). EPP amplitude rundown during continuous trains of activation was attenuated by approximately 10% in the overloaded group (P < 0.01). Also, during intermittent activation, the overload protocol attenuated EPP amplitude rundown, mainly by enhancing EPP amplitude recovery by approximately 10% during the quiescent periods (P < 0.01). Although the present results show that both the degree and direction of adaptation are similar to what has been observed at rat soleus neuromuscular junctions following an endurance training protocol, there are important nuances between the results, suggesting different mechanisms through which these changes may occur.     

Modulation of acetylcholine release in the ventral striatum by histamine receptors

Inflammation Research -     

Effects of sleep on pain-related somatosensory evoked potentials in humans

We investigated effects of sleep on pain-related somatosensory evoked potentials (SEP) following painful electrical stimulation of the left index finger. The biggest advantage of this method is that signals ascending through both A-beta fibers relating to touch and A-delta fibers relating to pain can be recorded simultaneously. While the subject was awake, non-painful stimulation evoked early- and middle latency components, N20, P30 and N60, at the C4 electrode, and painful stimulation evoked not only early- and middle latency components at the C4 but also later pain-specific components, N130 and P240, at the Cz electrode. During sleep, N20 and P30 did not show a significant change in amplitude, N60 showed a slight but significant amplitude reduction, and N130 and P240 significantly decreased in amplitude or disappeared, as compared with those while awake. Therefore, we speculate on the mechanisms generating each component as follows; (1) N20 and P30 are the primary components generated in SI ascending through A-beta fibers. (2) N60 is the secondary component generated in SI involving cognitive function to some degree. (3) N130-P240 are the pain-specific components ascending through A-delta fibers, and closely related to cognitive function, because they were much affected by consciousness, different from the components ascending through A-beta fibers.