Infections after bone allograft surgery: a prospective study by a hospital bone bank using frozen femoral heads from living donors

In the advent of the EU guidelines 2004/23/EG and 2006/17/EG requiring extensive safety and quality steps in bone banking, the prevalence and risk of infection disease transmission from bone allograft needs to be reconsidered. Therefore, we prospectively reviewed the screening process of bone donations and the outcome of surgeries utilizing bone allografts from our internal hospital bone bank with regard to infections according to CDC criteria. One-hundred and eighty-eight allogenic bone transplantation procedures in 160 patients were followed-up for 12–64 months (mean 32 months). Bacterial infection occurred in 11 patients, the overall infection rate therefore was 6.9%. After review of the clinical and intraoperative findings, none of the infections were likely to have been caused by the bone graft. Although no follow-up serologic testing was performed, no HIV of hepatitis infections were observed. Frozen bone allografts derived from live donors and provided by hospitals can generally be considered safe. However, without new and relevant clinical expertise, continuing this technique will be impeded by the new EU guidelines and their national implementations.     

Incidence and Risk Factors for Severe Bacterial Infections in People Living with HIV. ANRS CO3 Aquitaine Cohort, 2000–2012

Severe non-AIDS bacterial infections (SBI) are the leading cause of hospital admissions among people living with HIV (PLHIV) in industrialized countries. We aimed to estimate the incidence of SBI and their risk factors in a large prospective cohort of PLHIV patients over a 13-year period in France. Patients followed up in the ANRS CO3 Aquitaine cohort between 2000 and 2012 were eligible; SBI was defined as a clinical diagnosis associated with hospitalization of ≥48 hours or death. Survival analysis was conducted to identify risk factors for SBI.Total follow-up duration was 39,256 person-years [PY] (31,370 PY on antiretroviral treatment [ART]). The incidence of SBI decreased from 26.7/1000 PY [95% CI: 22.9–30.5] over the period 2000–2002 to 11.9/1000 PY [10.1–13.8] in 2009–2012 (p <0.0001). Factors independently associated to increased risk of SBI were: plasma HIVRNA>50 copies/mL (Hazard Ratio [HR] = 5.1, 95% Confidence Interval: 4.2–6.2), CD4 count <500 cells/mm³ and CD4/CD8 ratio <0.8 (with a dose-response relationship for both markers), history of cancer (HR = 1.4 [1.0–1.9]), AIDS stage (HR = 1.7 [1.3–2.1]) and HCV coinfection (HR = 1.4, [1.1–1.6]). HIV-positive patients with diabetes were more prone to SBI (HR = 1.6 [0.9–2.6]). Incidence of SBI decreased over a 13-year period due to the improvement in the virological and immune status of PLHIV on ART. Risk factors for SBI include low CD4 count and detectable HIV RNA, but also CD4/CD8 ratio, HCV coinfection, history of cancer and diabetes, comorbid conditions that have been frequent among PLHIV in recent years.     

Rapid preparation of the mitotic kinesin Eg5 inhibitor monastrol using controlled microwave-assisted synthesis

We present here a protocol for the synthesis of the dihydropyrimidine (DHPM) derivative monastrol, which is known to be a specific mitotic kinesin Eg5 inhibitor. By applying controlled microwave heating under sealed-vessel conditions, the synthesis via the one-pot three-component Biginelli condensation can be performed in a shorter reaction time (30 min) compared with conventional heating methods that normally require several hours of reflux heating. For the purification of the crude target compound, two different methods are presented. The first protocol includes a simple precipitation/filtration step to provide monastrol in 76% isolated yield and high purity so that no recrystallization step is necessary. This can be ascribed to the microwave heating technology in which less side-product formation is typically one of the advantages. In an alternative purification step, column chromatography is performed, which provides the product in a slightly higher yield (86%). Monastrol synthesis can be conducted in approximately 2 h by employing the precipitation/filtration purification method.     

Type II fatty acid synthesis is essential only for malaria parasite late liver stage development

Intracellular malaria parasites require lipids for growth and replication. They possess a prokaryotic type II fatty acid synthesis (FAS II) pathway that localizes to the apicoplast plastid organelle and is assumed to be necessary for pathogenic blood stage replication. However, the importance of FAS II throughout the complex parasite life cycle remains unknown. We show in a rodent malaria model that FAS II enzymes localize to the sporozoite and liver stage apicoplast. Targeted deletion of FabB/F , a critical enzyme in fatty acid synthesis, did not affect parasite blood stage replication, mosquito stage development and initial infection in the liver. This was confirmed by knockout of FabZ , another critical FAS II enzyme. However, FAS II-deficient Plasmodium yoelii liver stages failed to form exo-erythrocytic merozoites, the invasive stage that first initiates blood stage infection. Furthermore, deletion of FabI in the human malaria parasite Plasmodium falciparum did not show a reduction in asexual blood stage replication in vitro . Malaria parasites therefore depend on the intrinsic FAS II pathway only at one specific life cycle transition point, from liver to blood.     

Proton-Nuclear Magnetic Resonance Analyses of the Substrate Specificity of a β-Ketolase from Pseudomonas putida, Acetopyruvate Hydrolase

A revised purification of acetopyruvate hydrolase from orcinol-grown Pseudomonas putida ORC is described. This carbon-carbon bond hydrolase, which is the last inducible enzyme of the orcinol catabolic pathway, is monomeric with a molecular size of approximately 38 kDa; it hydrolyzes acetopyruvate to equimolar quantities of acetate and pyruvate. We have previously described the aqueous-solution structures of acetopyruvate at pH 7.5 and several synthesized analogues by (1)H-nuclear magnetic resonance (NMR)-Fourier transform (FT) experiments. Three (1)H signals (2.2 to 2.4 ppm) of the methyl group are assigned unambiguously to the carboxylate anions of 2,4-diketo, 2-enol-4-keto, and 2-hydrate-4-keto forms (40:50:10). A (1)H-NMR assay for acetopyruvate hydrolase was used to study the kinetics and stoichiometries of reactions within a single reaction mixture (0.7 ml) by monitoring the three methyl-group signals of acetopyruvate and of the products acetate and pyruvate. Examination of 4-tert-butyl-2,4-diketobutanoate hydrolysis by the same method allowed the conclusion that it is the carboxylate 2-enol form(s) or carbanion(s) that is the actual substrate(s) of hydrolysis. Substrate analogues of 2,4-diketobutanoate with 4-phenyl or 4-benzyl groups are very poor substrates for the enzyme, whereas the 4-cyclohexyl analogue is readily hydrolyzed. In aqueous solution, the arene analogues do not form a stable 2-enol structure but exist principally as a delocalized pi-electron system in conjugation with the aromatic ring. The effects of several divalent metal ions on solution structures were studied, and a tentative conclusion that the enol forms are coordinated to Mg(2+) bound to the enzyme was made. (1)H-(2)H exchange reactions showed the complete, fast equilibration of (2)H into the C-3 of acetopyruvate chemically; this accounts for the appearance of (2)H in the product pyruvate. The C-3 of the product pyruvate was similarly labelled, but this exchange was only enzyme catalyzed; the methyl group of acetate did not undergo an exchange reaction. The unexpected preference for bulky 4-alkyl-group analogues is discussed in an evolutionary context for carbon-carbon bond hydrolases. Routine one-dimensional (1)H-NMR in normal (1)H(2)O is a new method for rapid, noninvasive assays of enzymic activities to obtain the kinetics and stoichiometries of reactions in single reaction mixtures. Assessments of the solution structures of both substrates and products are also shown.