Role(s) of TMA in polymerization.

Quenched-flow data for propene polymerization with rac-Me2Si(2-Me-4-Ph-1-indenyl)2ZrCl2/MAO support a picture where removal of MAO qualitatively changes the kinetic profile from a mainly enthalpic to a mainly entropic barrier. DFT studies suggest that a not previously recognized singly-bridged end-on coordination mode of Me6Al2 to catalytically active centers may be kinetically relevant as a resting state. In contrast, the more traditional doubly-bridged complex of Me3Al is proposed to be more relevant to chain transfer to cocatalyst.

Olefin polymerisation catalysts: when perfection is not enough.

Despite decades of thorough mechanistic investigations, it is still hard to predict the activity of a novel olefin polymerisation catalyst, even when the precursor is a well-defined molecular entity. In the present study, we highlight the crucial importance of activation entropy on the polymerisation rate and how weak interactions of the catalytic species with electron donating species in the reaction pool can ultimately lower the activation free energy.

Associação de variáveis ambientais à ocorrência de leptospirose canina e humana na cidade de São Paulo / Association of environmental variables with the leptospirosis occurrence in dogs and humans at São Paulo city

Foi realizada uma análise espacial da ocorrência de leptospirose humana e canina na Supervisão de Vigilância em Saúde do Butantã, situada no município de São Paulo, no ano de 2007, associada a variáveis ambientais de risco, tais como: focos de enchente e áreas de desratização. Foram encontrados aglomerados espaciais de pontos de alagamentos em 12 setores censitários e de casos de leptospirose humana em quatro setores censitários, sem correlação entre ambos. Não foram encontrados agrupamentos de casos em cães, possivelmente devido à subnotificação. As proporções casos humanos de leptospirose : população humana dentro e fora da área de desratização foram 7:199.600 e 9:257.980, respectivamente. Conclui-se que medidas de controle de roedores como a desratização foram responsáveis pela minimização dos efeitos dos fatores de risco para a transmissão de leptospirose para humanos.

A spatial analysis of the human and canine leptospirosis occurrence was performed in São Paulo city in 2007, associated with environmental risk variables such as flooding and rodent control sites. Clusters of flooding sites were found in 12 census sectors, and human leptospirosis in 4 census sectors, without correlation between them. Clusters of canine cases were not found, possibly due to lack of notification. The proportions of human cases in and out of rodent control areas were, respectively, 7:199,600 and 9:257,980. Rodent control measures minimized the effects of the risk factors in the leptospirosis transmission to humans.

Infection with Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae in solid organ transplantation.

Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae is spreading globally and represents a challenge in infection control and treatment. Solid organ transplant (SOT) recipients are especially at risk for infection by multidrug-resistant bacteria, and little is known about infection with KPC-producing organisms in this setting. The aim of this study was to describe the clinical and microbiologic aspects of KPC-producing K. pneumoniae infections in SOT recipients. A KPC-2-producing K. pneumoniae outbreak was identified in a public teaching tertiary care hospital in São Paulo, Brazil, in June 2009. During the outbreak, cases of KPC-2-producing K. pneumoniae infection in SOT recipients occurred between July 2009 and February 2010; these cases were retrospectively reviewed. Overall, 12 episodes of infection with KPC-producing K. pneumoniae occurred in 2 heart, 4 liver, and 6 kidney transplant recipients with incidence rates of 16.7%, 12.9%, and 26.3% in heart, liver, and kidney transplantation, respectively. Infection occurred at a median time of 20 days after transplantation. Primary infection sites were as follows: 4 urinary tract infections, 4 bloodstream infections, 2 pneumonias, and 2 surgical site infections. All patients except one had received antibiotics in the last 30 days, mostly piperacillin-tazobactam or glycopeptides. All strains exhibited susceptibility to amikacin and gentamicin. Patients were treated with tigecycline plus polymyxin B (3 cases), polymyxin B plus carbapenem (3 cases), polymyxin B alone (3 cases), or tigecycline plus imipenem (1 case). In 2 cases, patients received only carbapenem, and death occurred before the final culture result. The overall 30-day mortality rate was 42%. In this series of KPC-producing K. pneumoniae infection in SOT recipients, the infection occurrence was high during an institutional outbreak and was potentially life threatening.

Infection with Klebsiella pneumonia carbapenemase (KPC)-producing K. pneumonia in solid organ transplantation

Abstract: Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae is spreading globally and represents achallenge in infection control and treatment. Solid organtransplant (SOT) recipients are especially at risk for infection bymultidrug-resistant bacteria, and little is known about infectionwith KPC-producing organisms in this setting. The aim of thisstudy was to describe the clinical and microbiologic aspects ofKPC-producing K. pneumoniae infections in SOT recipients. AKPC-2-producing K. pneumoniae outbreak was identified in apublic teaching tertiary care hospital in Sa˜o Paulo, Brazil, in June2009. During the outbreak, cases of KPC-2-producing K.pneumoniae infection in SOT recipients occurred between July2009 and February 2010; these cases were retrospectivelyreviewed. Overall, 12 episodes of infection with KPC-producingK. pneumoniae occurred in 2 heart, 4 liver, and 6 kidneytransplant recipients with incidence rates of 16.7%, 12.9%, and26.3% in heart, liver, and kidney transplantation, respectively.Infection occurred at a median time of 20 days aftertransplantation. Primary infection sites were as follows: 4 urinarytract infections, 4 bloodstream infections, 2 pneumonias, and 2surgical site infections. All patients except one had receivedantibiotics in the last 30 days, mostly piperacillin-tazobactam orglycopeptides. All strains exhibited susceptibility to amikacin andgentamicin. Patients were treated with tigecycline plus polymyxinB (3 cases), polymyxin B plus carbapenem (3 cases), polymyxin Balone (3 cases), or tigecycline plus imipenem (1 case). In 2 cases,patients received only carbapenem, and death occurred before thefinal culture result. The overall 30-day mortality rate was 42%. Inthis series of KPC-producing K. pneumoniae infection in SOTrecipients, the infection occurrence was high during aninstitutional outbreak and was potentially life threatening.

Renal failure as a determinant of mortality after cardiac transplantation.

INTRODUCTION: Patients with heart failure frequently develop renal failure, which increases the mortality rate among patients undergoing cardiac transplantation. PURPOSE: To determine whether preoperative renal function influenced postoperative mortality in cardiac transplantation recipients. MATERIALS AND METHODS: The measurements of plasma urea, plasma creatinine, and 24-hour creatinine clearance in patients who underwent cardiac transplantation were correlated with mortality at 30, 90, and 365 days after the procedure, using Student t test for continuous variables and the chi-square test for categorical variables. RESULTS: All variables correlated with mortality, particularly plasma creatinine at 30, 90, and 365 days (P =.029,.003, and.0029, respectively). CONCLUSION: Preoperative renal failure is a mortality indicator in cardiac transplantation recipients.

Renal Failure as a Determinant of Mortality After Cardiac Transplantation

Introduction. Patients with heart failure frequently develop renal failure, which increasesthe mortality rate among patients undergoing cardiac transplantation.Purpose. To determine whether preoperative renal function influenced postoperativemortality in cardiac transplantation recipients.Materials and Methods. The measurements of plasma urea, plasma creatinine, and 24-hour creatinine clearance in patients who underwent cardiac transplantation werecorrelated with mortality at 30, 90, and 365 days after the procedure, using Student t test for continuous variables and the chi-square test for categorical variables.Results. All variables correlated with mortality, particularly plasma creatinine at 30, 90,and 365 days (P .029, .003, and .0029, respectively).Conclusion. Preoperative renal failure is a mortality indicator in cardiac transplantation recipients.