Study on the jarosite mediated by bioleaching of pyrrhotite using Acidthiobacillus ferrooxidans / Estudo sobre a jarosita mediada pela biolixiviação da pirrotita usando Acidithiobacillus ferrooxidans

Precipitation of jarosite is a very important phenomenon that is observed in the bioleaching of pyrrhotite by Acidthiobacillus ferrooxidans (A. ferrooxidans). Jarosite is a major secondary mineral formed in acid supergene environment by oxidation of metal sulphide. The formation of jarosite could decrease leached percentage. The Eh-pH diagram of FeS1.12-H2O showed that the thermodynamic parameters of the jarosite were exists steadily on Eh=360 ～ 800, pH=2.8 ～ 5, and the results of pH condition test is consonant with the conclusions of thermodynamic analysis. By means of XRD and SEM, it could indicate that full propagation of A. ferrooxidans in the solution is beneficial to the formation of jarosite and jarosite mediated by bacterial has a better crystalline form than that synthesized by chemical method. This study indicates that pH value and ferrous/ferric iron concentration are key factors affecting the formation of jarosite. Leached percentage is higher when frequency was set more than 2.0. It is crucial to minimize jarosite formation in order to increase factory's efficiency.

A precipitação de jarosite é um fenômeno muito importante que é observado na biolixiviação da pirrotita por Acidithiobacillus ferrooxidans (A. ferrooxidans). A jarosita é um mineral secundário principal formado no ambiente supergênico ácido pela oxidação do sulfureto do metal. A formação de jarosite pode diminuir a porcentagem de lixiviação. O diagrama de Eh-pH de FeS1.12-H2O mostrou que os parâmetros termodinâmicos da jarosite estavam firmemente presentes em Eh = 360~800, pH = 2.8~5, e os resultados do teste de condição de pH estão em consonância com as conclusões da análise termodinâmica. Por meio de XRD e SEM, pode ser indicado que a propagação completa de A. ferrooxidans na solução é benéfica para a formação de jarosite e jarosite mediada por bactérias tem uma forma cristalina melhor do que a sintetizada por método químico. Este estudo indica que o valor do pH e a concentração de ferro ferroso/férrico são fatores chave que afetam a formação de jarosite. A porcentagem de lixiviação é maior quando a freqüência foi ajustada a mais de 2,0. É crucial para minimizar a formação de jarosite, a fim de aumentar a eficiência da fábrica.

Evaluation of procalcitonin, C-reactive protein, interleukin-6 & serum amyloid A as diagnostic biomarkers of bacterial infection in febrile patients.

Background & objectives: Early identification of bacterial infection in patients with fever is important for prompt treatment. However, the available parameters such as C-reactive protein (CRP) and leukocyte counts are not very specific. This study was aimed to assess the diagnostic value of procalcitonin (PCT), CRP, interleukin-6 (IL-6) and serum amyloid A (SAA) for bacterial infection in febrile patients. Methods: Serum samples were collected from febrile patients between January and December 2012 and processed for blood cultures. PCT, IL-6, CRP and SAA levels were measured. The patients were divided into three groups according to the final diagnosis: bacteraemia group (group1), bacterial infection with negative blood culture (group 2) and non-bacterial infection group (group 3). Results: There were significant (P<0.05) difference in the levels of PCT, CRP, IL-6 and SAA among the three groups. The PCT levels of patients with gram-positive bacterial infections were lower than gram-negative bacterial infections (0.53 vs 2.13, P < 0.01). The best cut-off value to detect bacterial infections was 0.26 ng/ml for PCT. PCT, CRP, IL-6 and SAA had areas under the curve of 0.804, 0.693, 0.658 and 0.687, respectively. Interpretation & conclusions: Our results showed PCT as a valuable marker of bacterial infections in febrile patients. PCT was superior to CRP, IL-6 or SAA in the early identification of bacterial infection. More prospective and large scale studies are warranted to confirm these findings.

Biapenem versus meropenem in the treatment of bacterial infections: a multicenter, randomized, controlled clinical trial.

Background & objectives: Biapenem is a newly developed carbapenem to treat moderate and severe bacterial infections. This multicenter, randomized, parallel-controlled clinical trial was conducted to compare the clinical efficacy, bacterial eradication rates and safety of biapenem and meropenem in the treatment of bacterial lower respiratory tract infections and urinary tract infections (UTIs) at nine centres in China. Methods: Patients diagnosed with bacterial lower respiratory tract infections or UTIs were randomly assigned to receive either biapenem (300 mg every 12 h) or meropenem (500 mg every 8 h) by intravenous infusion for 7 to 14 days according to their disease severity. The overall clinical efficacy, bacterial eradication rates and drug-related adverse reactions of biapenem and meropenem were analyzed. Results: A total of 272 enrolled cases were included in the intent-to-treat (ITT) analysis and safety analysis. There were no differences in demographics and baseline medical characteristics between biapenem group and meropenem group. The overall clinical efficacies of biapenem and meropenem were not significantly different, 94.70 per cent (125/132) vs. 93.94 per cent (124/132). The overall bacterial eradication rates of biapenem and meropenem showed no significant difference, 96.39 per cent (80/83) vs. 93.75 per cent (75/80). Drug-related adverse reactions were comparable in biapenem and meropenem groups with the incidence of 11.76 per cent (16/136) and 15.44 per cent (21/136), respectively. The most common symptoms of biapenem-related adverse reactions were rash (2.2%) and gastrointestinal distress (1.5%). Interpretation & conclusions: Biapenem was non-inferior to meropenem and was well-tolerated in the treatment of moderate and severe lower respiratory tract infections and UTIs.

Inhibition of 5-HT3 Receptors-activated Currents by Cannabinoids in Rat Trigeminal Ganglion Neurons / 华中科技大学学报（医学）（英德文版）

This study investigated the modulatory effect of synthetic cannbinoids WIN55,212-2 on 5-HT3 receptor-activated currents (I5-Hr3) in cultured rat trigeminal ganglion (TG) neurons using whole-cell patch clamp technique.The results showed that:(!) The majority of examined neurons (78.70％) were sensitive to 5-HT (3-300 μmol/L).5-HT induced inward currents in a concentrationdependent manner and the currents were blocked by ICS 205-930 (1 μmol/L),a selective antagonist of the 5-HT3 receptor; (2) Pre-application of WIN55,212-2 (0.01-1 μmol/L) significantly inhibited I5-HT3 reversibly in concentration-dependent and voltage-independent manners.The concentration-response curve of 5-HT3 receptor was shifted downward by WIN55,212-2 without any change of the threshold value.The EC50values of two curves were very close (17.5±4.5) μmol/L vs.(15.2±4.5) μmol/L and WIN55,212-2 decreased the maximal amplitude of I5-HI3 by (48.65±4.15)％; (3) Neither AM281,a selective CBI receptor antagonist,nor AM630,a selective CB2 receptor antagonist reversed the inhibition of I5-HT3by WIN55,212-2; (4) When WIN55,212-2 was given from 15 to 120 s before 5-HT application,inhibitory effect was gradually increased and the maximal inhibition took place at 90 s,and the inhibition remained at the same level after 90 s.We are led to concluded thatWIN55,212-2 inhibited I5-Hr3 significantly and neither CB1 receptor antagonist nor CB2 receptor antagonist could reverse the inhibition of I5-HT3 by WIN55,212-2.Moreover,WIN55,212-2 is not an open channel blocker (OCB) of 5-HT3 receptor.WIN55,212-2 significantly inhibited 5-HT-activated currents in a non-competitive manner.The inhibition of I5-HT3 by WIN55,212-2 is probably new one of peripheral analgesic mechanisms of WIN55,212-2,but the mechanism by which WIN55,212-2 inhibits I5-HT3 warrants further investigation.

In-house polymerase chain reaction for affordable and sustainable Chlamydia trachomatis detection in Trinidad and Tobago

OBJECTIVES: To provide a preliminary assessment of in-house polymerase chain reaction (PCR) as an alternative to the more costly commercial test for detection of asymptomatic infection by Chlamydia trachomatis and to provide much needed demographic data on infection indicators within the Trinidad and Tobago public health care system. METHODS: An inexpensive in-house nested-PCR with an Internal Amplification Control was used to detect C. trachomatis and Neisseria gonorrhoeae in urine samples collected from 273 apparently healthy, pregnant women from March-September 2004 in Trinidad, West Indies. Demographic information on participants was collected and subjected to statistical analyses. RESULTS: C. trachomatis was detected in 57/273 (21 percent) samples, of which 5 (2 percent) were also positive for N. gonorrhoeae. Infection correlated well with certain demographic parameters, with the highest incidence of C. trachomatis infection found among pregnant women that were single or of African descent. CONCLUSIONS: Given the lack of commercial tests in Trinidad, in-house PCR is an inexpensive alternative that can be used to detect asymptomatic infections of C. trachomatis and to provide demographic information needed for interventions by the public health care system.

OBJETIVOS: Hacer una evaluación preliminar de un sistema autóctono para la detección de la infección asintomática por Chlamydia trachomatis mediante la reacción en cadena de la polimerasa (RCP), como alternativa a los costosos sistemas comerciales, y ofrecer datos demográficos muy necesarios relacionados con los indicadores de esta infección en el sistema de salud pública de Trinidad y Tobago. MÉTODOS: Se empleó un sistema autóctono y económico de RCP anidada con control interno de la amplificación para la detección de C. trachomatis y Neisseria gonorrhoeae en muestras de orina de 273 mujeres embarazadas asintomáticas, entre marzo y septiembre de 2004 en Trinidad y Tobago, Indias Occidentales. Se obtuvo la información demográfica de las participantes y se sometió a análisis estadístico. RESULTADOS: Se detectó C. trachomatis en 57/273 (21 por ciento) muestras, de las cuales 5 (2 por ciento) fueron también positivas para N. gonorrhoeae. La infección se correlacionó bien con algunos parámetros demográficos; la mayor incidencia de la infección por C. trachomatis se observó en las mujeres embarazadas solteras o de ascendencia africana. CONCLUSIONES: Debido al déficit de sistemas de diagnóstico comerciales en Trinidad, la RCP autóctona es una alternativa económica que puede emplearse para detectar la infección asintomática por C. trachomatis y obtener la información demográfica necesaria para que el sistema de salud pública implemente intervenciones.