Low-level release of Shiga-like toxin (verocytotoxin) and endotoxin from enterohemorrhagic Escherichia coli treated with imipenem

Shiga-like toxin (SLT) and endotoxin may participate in the pathogenesis of enterohemorrhagic Escherichia coli (EHEC) infection. Levels of release of SLT and endotoxin from EHEC treated in vitro with antibiotics were estimated. There were differential levels of release of SLT and endotoxin from EHEC treated with different antibiotics. Treatment of EHEC strains, namely, E. coli O157, O111, and O26, with imipenem induced much lower levels of release of SLT and endotoxin than treatment with ceftazidime.     

Synthesis of Heterocycle-Containing [60]Fullerene Derivatives

Fullerene functionalization with heterocycles is reviewed, focusing attention on cycloaddition methodology and oxidative heterocyclization.¹     

Arabinofuranosyl-terminated and mannosylated lipoarabinomannans from Mycobacterium tuberculosis induce different levels of interleukin-12 expression in murine macrophages

Lipoarabinomannan (LAM) is a major surface lipoglycan of Mycobacterium tuberculosis. In the present study, we demonstrated that arabinofuranosyl-terminated LAM (AraLAM) derived from a rapidly growing Mycobacterium sp., but not extensively mannosylated LAM derived from the Erdman strain, is capable of inducing interleukin-12 (IL-12) expression in murine macrophages. Since IL-12 is known to drive the differentiation of naive T cells toward T-helper type 1 (Th1) cell development, AraLAM may be an effective adjuvant in vaccines and immunotherapies that need Th1 responses.     

Accuracy of treadmill exercise electrocardiography in detecting restenosis following single-vessel percutaneous transluminal coronary angioplasty

To develop an improved method for diagnosing restenosis using treadmill exercise electrocardiography (ECG) following percutaneous transluminal coronary angioplasty (PTCA), we prospectively evaluated 46 patients who underwent PTCA for the treatment of single-vessel coronary artery disease and who did not have a history of myocardial infarction. Treadmill exercise ECG and coronary angiography were performed 3 months after PTCA to determine their accuracy in diagnosing restenosis based on standard ST-segment depression criteria, the difference between the maximum ST-segment depression before and 3 months after PTCA (< or =0.5 mm: positive; >0.5 mm: negative), and the difference between sigmaST-segment depression before PTCA and 3 months after PTCA (< or = 1.5 mm: positive; > 1.5 mm: negative). The sensitivity, specificity, and diagnostic accuracy of standard ST-segment depression criteria were 65%, 66%, and 65%, respectively. The sensitivity, specificity, and accuracy for the difference in maximum ST-segment depression were 77%, 76%, and 76%, respectively, whereas the values for the difference in sigmaST-segment depression were 77%, 83%, and 80%, respectively. Based on these results, we conclude that using the difference between ST-segment depression before and after PTCA improves the accuracy of treadmill exercise ECG for diagnosing restenosis.     

Role of microtubules in the contractile dysfunction of hypertrophied myocardium

OBJECTIVES: We sought to determine whether the ameliorative effects of microtubule depolymerization on cellular contractile dysfunction in pressure overload cardiac hypertrophy apply at the tissue level. BACKGROUND: A selective and persistent increase in microtubule density causes decreased contractile function of cardiocytes from cats with hypertrophy produced by chronic right ventricular (RV) pressure overloading. Microtubule depolymerization by colchicine normalizes contractility in these isolated cardiocytes. However, whether these changes in cellular function might contribute to changes in function at the more highly integrated and complex cardiac tissue level was unknown. METHODS: Accordingly, RV papillary muscles were isolated from 25 cats with RV pressure overload hypertrophy induced by pulmonary artery banding (PAB) for 4 weeks and 25 control cats. Contractile state was measured using physiologically sequenced contractions before and 90 min after treatment with 10(-5) mol/liter colchicine. RESULTS: The PAB significantly increased RV systolic pressure and the RV weight/body weight ratio in PAB; it significantly decreased developed tension from 59+/-3 mN/mm2 in control to 25+/-4 mN/mm2 in PAB, shortening extent from 0.21+/-0.01 muscle lengths (ML) in control to 0.12+/-0.01 ML in PAB, and shortening rate from 1.12+/-0.07 ML/s in control to 0.55+/-0.03 ML/s in PAB. Indirect immunofluorescence confocal microscopy showed that PAB muscles had a selective increase in microtubule density and that colchicine caused complete microtubule depolymerization in both control and PAB papillary muscles. Microtubule depolymerization normalized myocardial contractility in papillary muscles of PAB cats but did not alter contractility in control muscles. CONCLUSIONS: Excess microtubule density, therefore, is equally important to both cellular and to myocardial contractile dysfunction caused by chronic, severe pressure-overload cardiac hypertrophy.