Overexpression, purification and characterisation of the Plasmodium falciparum Hsp70-z (PfHsp70-z) protein.

Six Hsp70-like genes are represented on the genome of Plasmodium falciparum. Of these two occur i0n the cytosol: P. falciparum Hsp70-z (PfHsp70-z) and PfHsp70-1. PfHsp70-1 is a well characterised canonical Hsp70 that facilitates protein quality control and is crucial for the development of malaria parasites. There is very little known about PfHsp70-z. However, PfHsp70-z is known to be essential and is implicated in suppressing aggregation of asparagine-rich proteins of P. falciparum. In addition, its expression at the clinical stage of malaria correlates with disease prognosis. Based on structural evidence PfHsp70-z belongs to the Hsp110 family of proteins. Since Hsp110 proteins have been described as nucleotide exchange factors (NEFs) of their canonical Hsp70 counterparts, it has been speculated that PfHsp70-z may serve as a NEF of PfHsp70-1. In the current study, P. falciparum cells cultured in vitro were subjected to heat stress, triggering the enhanced expression of PfHsp70-z. Biochemical assays conducted using recombinant PfHsp70-z protein demonstrated that the protein is heat stable and possesses ATPase activity. Furthermore, we observed that PfHsp70-z is capable of self-association. The structural-functional features of PfHsp70-z provide further evidence for its role as a chaperone and possible nucleotide exchange factor of PfHsp70-1.This project was through a grant (L1/402/ 14-1) provided to AS by the Deutsche Forchungsgemeinshaft (DFG) under the theme, “German–African Cooperation Projects in Infectology”. The authors are grateful to the Department of Science and Technology/National Research Foundation (NRF) of South Africa for providing an equipment grant (grant UID, 75464) to AS and (grant UID, 78558) to EP. HWD was awarded a research grant (64788) by the NRF (South Africa). AS is a recipient of a Georg Foster researchNCS201

Overexpression, purification and characterisation of the Plasmodium falciparum Hsp70-z (PfHsp70-z) protein.

Six Hsp70-like genes are represented on the genome of Plasmodium falciparum. Of these two occur i0n the cytosol: P. falciparum Hsp70-z (PfHsp70-z) and PfHsp70-1. PfHsp70-1 is a well characterised canonical Hsp70 that facilitates protein quality control and is crucial for the development of malaria parasites. There is very little known about PfHsp70-z. However, PfHsp70-z is known to be essential and is implicated in suppressing aggregation of asparagine-rich proteins of P. falciparum. In addition, its expression at the clinical stage of malaria correlates with disease prognosis. Based on structural evidence PfHsp70-z belongs to the Hsp110 family of proteins. Since Hsp110 proteins have been described as nucleotide exchange factors (NEFs) of their canonical Hsp70 counterparts, it has been speculated that PfHsp70-z may serve as a NEF of PfHsp70-1. In the current study, P. falciparum cells cultured in vitro were subjected to heat stress, triggering the enhanced expression of PfHsp70-z. Biochemical assays conducted using recombinant PfHsp70-z protein demonstrated that the protein is heat stable and possesses ATPase activity. Furthermore, we observed that PfHsp70-z is capable of self-association. The structural-functional features of PfHsp70-z provide further evidence for its role as a chaperone and possible nucleotide exchange factor of PfHsp70-1.This project was through a grant (L1/402/ 14-1) provided to AS by the Deutsche Forchungsgemeinshaft (DFG) under the theme, “German–African Cooperation Projects in Infectology”. The authors are grateful to the Department of Science and Technology/National Research Foundation (NRF) of South Africa for providing an equipment grant (grant UID, 75464) to AS and (grant UID, 78558) to EP. HWD was awarded a research grant (64788) by the NRF (South Africa). AS is a recipient of a Georg Foster researchNCS201

Selective lysis of erythrocytes infected with the trophozoite stage of Plasmodium falciparum by polyene macrolide antibiotics

The continuous increase in strains of the human malaria parasite Plasmodium falciparum resistant to most front-line antimalarial compounds is reason for grave clinical concern. The search for new drugs led us to investigate a number of membrane active polyene macrolide antibiotics, such as amphotericin B, nystatin, filipin and natamycin. The interaction of these compounds with sterols in bilayer cell membranes can lead to cell damage and ultimately cell lysis. The malaria parasite modifies the host erythrocyte membrane by changing the protein and lipid composition and thus the infected cell could be a selective target for membrane active compounds. We found that erythrocytes infected with the trophozoite stage of P. falciparum were particularly susceptible to lysis by amphotericin B (Fungizone™) and, to a lesser extent, nystatin, as determined by ELISA and various microscopy assays. Liposomal amphotericin B (AmBisome™) displayed a similar specificity for parasitised erythrocytes, but complete lysis required a longer incubation period. In contrast, filipin and natamycin did not distinguish between normal and parasite-infected erythrocytes, but lysed both at similar concentrations. In addition, when added to ring-stage cultures, the amphotericin B preparations and nystatin produced a marked disruption in parasite morphology in less than 2 h without an accompanying permeabilisation of the infected host cell, suggesting a second plasmodicidal mode of action. The results imply that selected polyene macrolide antibiotics or their derivatives could find application in the treatment of severe malaria caused by of P. falciparum. © 2006 Elsevier Inc. All rights reserved.Articl

Entry deterrence in durable-goods monopoly

SIGLEAvailable from British Library Document Supply Centre-DSC:3597.937(0001) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Novel N-heterocyclic ylideneamine gold(i) complexes: Synthesis, characterisation and screening for antitumour and antimalarial activity

Ylideneamine functionalised heterocyclic ligands, 1,3-dimethyl-1,3-dihydro- benzimidazol-2-ylideneamine (I), 3-methyl-3H-benzothiazol-2-ylideneamine (II) or 3,4-dimethyl-3H-thiazol-2-ylideneamine (III), were employed in the preparation of a series of both charged and neutral gold(i) complexes consisting either of a Au(C6F5) fragment (1-3), a [Au(PPh3)] + unit (4-6) or a [Au(NHC)]+ unit (7) coordinated to the imine nitrogen of the neutral ylideneamine ligand. These complexes were fully characterised by various techniques including X-ray diffraction. In addition, the antitumour and antimalarial potential of selected compounds were assessed in a preliminary study aimed at determining the medicinal value of such compounds. Complexation of the azol-2-ylideneamine ligands with [Au(PPh3)] + increases their antitumour as well as antimalarial activity. © 2011 The Royal Society of Chemistry.Articl

Imidazo[1,2-a]pyridin-3-amines as potential HIV-1 non-nucleoside reverse transcriptase inhibitors

During random screening of a small in-house library of compounds, certain substituted imidazo[1,2-a]pyridines were found to be weak allosteric inhibitors of HIV-1 reverse transcriptase (RT). A library of these compounds was prepared using the Groebke reaction and a subset of compounds prepared from 2-chlorobenzaldehyde, cyclohexyl isocyanide and a 6-substituted 2-aminopyridine showed good inhibitory activity in enzymatic (RT) and HIV anti-infectivity MAGI whole cell assays. The compound showing the best anti-HIV-1 IIIB whole cell activity (MAGI IC50 = 0.18 μM, IC90 = 1.06 μM), along with a good selectivity index (>800), was 2-(2-chlorophenyl)-3- (cyclohexylamino)imidazo[1,2-a]pyridine-5-carbonitrile 38. © 2011 Elsevier Ltd. All rights reserved.Articl

Predicting the Need for Radiologic Imaging in Adults with Febrile Urinary Tract Infection

Background. Radiologic evaluation of adults with febrile urinary tract infection (UTI) is frequently performed to exclude urological disorders. This study aims to develop a clinical rule predicting need for radiologic imaging. Methods. We conducted a prospective, observational study including consecutive adults with febrile UTI at 8 emergency departments (EDs) in the Netherlands. Outcomes of ultrasounds and computed tomographs of the urinary tract were classified as "urgent urological disorder" (pyonephrosis or abscess), "nonurgent urologic disorder," "normal," and "incidental nonurological findings." Urgent and nonurgent urologic disorders were classified as " clinically relevant radiologic findings." The data of 5 EDs were used as the derivation cohort, and 3 EDs served as the validation cohort. Results. Three hundred forty-six patients were included in the derivation cohort. Radiologic imaging was performed for 245 patients (71%). A prediction rule was derived, being the presence of a history of urolithiasis, a urine pH >= 7.0, and/or renal insufficiency (estimated glomerular filtration rate, <= 40 mL/min/1.73 m(3)). This rule predicts clinically relevant radiologic findings with a negative predictive value (NPV) of 93% and positive predictive value (PPV) of 24% and urgent urological disorders with an NPV of 99% and a PPV of 10%. In the validation cohort (n = 131), the NPV and PPV for clinically relevant radiologic findings were 89% and 20%, respectively; for urgent urological disorders, the values were 100% and 11%, respectively. Potential reduction of radiologic imaging by implementing the prediction rule was 40%. Conclusions. Radiologic imaging can selectively be applied in adults with febrile UTI without loss of clinically relevant information by using a simple clinical prediction rule

Predicting the Need for Radiologic Imaging in Adults with Febrile Urinary Tract Infection

Background. Radiologic evaluation of adults with febrile urinary tract infection (UTI) is frequently performed to exclude urological disorders. This study aims to develop a clinical rule predicting need for radiologic imaging. Methods. We conducted a prospective, observational study including consecutive adults with febrile UTI at 8 emergency departments (EDs) in the Netherlands. Outcomes of ultrasounds and computed tomographs of the urinary tract were classified as "urgent urological disorder" (pyonephrosis or abscess), "nonurgent urologic disorder," "normal," and "incidental nonurological findings." Urgent and nonurgent urologic disorders were classified as " clinically relevant radiologic findings." The data of 5 EDs were used as the derivation cohort, and 3 EDs served as the validation cohort. Results. Three hundred forty-six patients were included in the derivation cohort. Radiologic imaging was performed for 245 patients (71%). A prediction rule was derived, being the presence of a history of urolithiasis, a urine pH >= 7.0, and/or renal insufficiency (estimated glomerular filtration rate, <= 40 mL/min/1.73 m(3)). This rule predicts clinically relevant radiologic findings with a negative predictive value (NPV) of 93% and positive predictive value (PPV) of 24% and urgent urological disorders with an NPV of 99% and a PPV of 10%. In the validation cohort (n = 131), the NPV and PPV for clinically relevant radiologic findings were 89% and 20%, respectively; for urgent urological disorders, the values were 100% and 11%, respectively. Potential reduction of radiologic imaging by implementing the prediction rule was 40%. Conclusions. Radiologic imaging can selectively be applied in adults with febrile UTI without loss of clinically relevant information by using a simple clinical prediction rule.Immunogenetics and cellular immunology of bacterial infectious disease