Pharmacokinetics and pharmacodynamics of intravenous artesunate during severe malaria treatment in Ugandan adults

ABSTRACT: BACKGROUND: Severe malaria is a medical emergency with high mortality. Prompt achievement of therapeutic concentrations of highly effective anti-malarial drugs reduces the risk of death. The aim of this study was to assess the pharmacokinetics and pharmacodynamics of intravenous artesunate in Ugandan adults with severe malaria. METHODS: Fourteen adults with severe falciparum malaria requiring parenteral therapy were treated with 2.4 mg/kg intravenous artesunate. Blood samples were collected after the initial dose and plasma concentrations of artesunate and dihydroartemisinin measured by solid-phase extraction and liquid chromatography-tandem mass spectrometry. The study was approved by the Makerere University Faculty of Medicine Research and Ethics Committee (Ref2010-015) and Uganda National Council of Science and Technology (HS605) and registered with ClinicalTrials.gov (NCT01122134). RESULTS: All study participants achieved prompt resolution of symptoms and complete parasite clearance with median (range) parasite clearance time of 17 (8-24) hours. Median (range) maximal artesunate concentration (Cmax) was 3260 (1020-164000) ng/mL, terminal elimination half-life (T1/2) was 0.25 (0.1-1.8) hours and total artesunate exposure (AUC) was 727 (290-111256) ngh/mL. Median (range) dihydroartemisinin Cmax was 3140 (1670-9530) ng/mL, with Tmax of 0.14 (0.6 - 6.07) hours and T1/2 of 1.31 (0.8-2.8) hours. Dihydroartemisinin AUC was 3492 (2183-6338) ngh/mL. None of the participants reported adverse events. CONCLUSIONS: Plasma concentrations of artesunate and dihydroartemisinin were achieved rapidly with rapid and complete symptom resolution and parasite clearance with no adverse events.     

VS411 Reduced Immune Activation and HIV-1 RNA Levels in 28 Days: Randomized Proof-of-Concept Study for AntiViral-HyperActivation Limiting Therapeutics

Background

A new class of antiretrovirals, AntiViral-HyperActivation Limiting Therapeutics (AV-HALTs), has been proposed as a disease-modifying therapy to both reduce Human Immunodeficiency Virus Type 1 (HIV-1) RNA levels and the excessive immune activation now recognized as the major driver of not only the continual loss of CD4⁺ T cells and progression to Acquired Immunodeficiency Syndrome (AIDS), but also of the emergence of both AIDS-defining and non-AIDS events that negatively impact upon morbidity and mortality despite successful (ie, fully suppressive) therapy. VS411, the first-in-class AV-HALT, combined low-dose, slow-release didanosine with low-dose hydroxycarbamide to accomplish both objectives with a favorable toxicity profile during short-term administration. Five dose combinations were administered as VS411 to test the AV-HALT Proof-of-Concept in HIV-1-infected subjects.

Methods

Multinational, double-blind, 28-day Phase 2a dose-ranging Proof-of-Concept study of antiviral activity, immunological parameters, safety, and genotypic resistance in 58 evaluable antiretroviral-naïve HIV-1-infected adults. Randomization and allocation to study arms were carried out by a central computer system. Results were analyzed by ANOVA, Kruskal-Wallis, ANCOVA, and two-tailed paired t tests.

Results

VS411 was well-tolerated, produced significant reductions of HIV-1 RNA levels, increased CD4⁺ T cell counts, and led to significant, rapid, unprecedented reductions of immune activation markers after 28 days despite incomplete viral suppression and without inhibiting HIV-1-specific immune responses. The didanosine 200 mg/HC 900 mg once-daily formulation demonstrated the greatest antiviral efficacy (HIV-1 RNA: −1.47 log₁₀ copies/mL; CD4⁺ T cell count: +135 cells/mm³) and fewest adverse events.

Conclusions

VS411 successfully established the Proof-of-Concept that AV-HALTs can combine antiviral efficacy with rapid, potentially beneficial reductions in the excessive immune system activation associated with HIV-1 disease. Rapid reductions in markers of immune system hyperactivation and cellular proliferation were obtained despite the fact that VS411 did not attain maximal suppression of HIV RNA, suggesting this effect was due to the HALT component.

Trial Registration

ITEudraCT 2007-002460-98     

Genome-wide copy number analysis uncovers a new HSCR gene: NRG3

Hirschsprung disease (HSCR) is a congenital disorder characterized by aganglionosis of the distal intestine. To assess the contribution of copy number variants (CNVs) to HSCR, we analysed the data generated from our previous genome-wide association study on HSCR patients, whereby we identified NRG1 as a new HSCR susceptibility locus. Analysis of 129 Chinese patients and 331 ethnically matched controls showed that HSCR patients have a greater burden of rare CNVs (p = 1.50 × 10(-5)), particularly for those encompassing genes (p = 5.00 × 10(-6)). Our study identified 246 rare-genic CNVs exclusive to patients. Among those, we detected a NRG3 deletion (p = 1.64 × 10(-3)). Subsequent follow-up (96 additional patients and 220 controls) on NRG3 revealed 9 deletions (combined p = 3.36 × 10(-5)) and 2 de novo duplications among patients and two deletions among controls. Importantly, NRG3 is a paralog of NRG1. Stratification of patients by presence/absence of HSCR-associated syndromes showed that while syndromic-HSCR patients carried significantly longer CNVs than the non-syndromic or controls (p = 1.50 × 10(-5)), non-syndromic patients were enriched in CNV number when compared to controls (p = 4.00 × 10(-6)) or the syndromic counterpart. Our results suggest a role for NRG3 in HSCR etiology and provide insights into the relative contribution of structural variants in both syndromic and non-syndromic HSCR. This would be the first genome-wide catalog of copy number variants identified in HSCR.     

Prokineticin-1 (Prok-1) works coordinately with glial cell line-derived neurotrophic factor (GDNF) to mediate proliferation and differentiation of enteric neural crest cells

Enteric neural crest cells (NCC) are multipotent progenitors which give rise to neurons and glia of the enteric nervous system (ENS) during fetal development. Glial cell line-derived neurotrophic factor (GDNF)/RET receptor tyrosine kinase (Ret) signaling is indispensable for their survival, migration and differentiation. Using microarray analysis and isolated NCCs, we found that 45 genes were differentially expressed after GDNF treatment (16 h), 29 of them were up-regulated including 8 previously undescribed genes. Prokineticin receptor 1 (PK-R1), a receptor for Prokineticins (Prok), was identified in our screen and shown to be consistently up-regulated by GDNF in enteric NCCs. Further, PK-R1 was persistently expressed at a lower level in the enteric ganglions of the c-Ret deficient mice when compared to that of the wild-type littermates. Subsequent functional analysis showed that GDNF potentiated the proliferative and differentiation effects of Prok-1 by up-regulating PK-R1 expression in enteric NCCs. In addition, expression analysis and gene knock-down experiments indicated that Prok-1 and GDNF signalings shared some common downstream targets. More importantly, Prok-1 could induce both proliferation and expression of differentiation markers of c-Ret deficient NCCs, suggesting that Prok-1 may also provide a complementary pathway to GDNF signaling. Taken together, these findings provide evidence that Prok-1 crosstalks with GDNF/Ret signaling and probably provides an additional layer of signaling refinement to maintain proliferation and differentiation of enteric NCCs.     

Subcellular fractionation of striatum: Sedimentation properties of dopaminergic synaptosomes

Linear sucrose density gradient centrifugation of a crude synaptosomal-mitochondrial preparation of rat striatum was performed at 82, 500g for 7.5, 15 and 30 min and 1, 4 and 20 h. After centrifugation various marker enzyme activities were measured throughout the gradients, viz. tyrosine hydroxylase (TH) and DOPA decarboxylase (DD) as markers of dopaminergic synaptosomes, lactate dehydrogenase (LDH) as a general synaptosomal marker and monoamine oxidase (MAO) as a mitochondrial marker. At all centrifugation times the distribution patterns of TH and DD activity coincided almost perfectly. Notable differences were found between the sedimentation properties of these TH/DD-containing particles and LDH-containing particles: TH and DD were symmetrically distributed in the gradient much sooner than LDH, at all centrifugation times the top of the TH and DD curves was lying deeper in the gradient than the highest LDH activity, and Th and DD became enriched in the gradients to a much greater extent than LDH. It is concluded that rat striatal dopaminergic synaptosomes form a relatively homogenous population of particles sedimenting faster into the gradients than the bulk of striatal synaptosomes does. This distinct sedimentation behaviour of the dopaminergic synaptosomes can be usefully applied for analytical purposes.     

Identification of D/D translocations in mentally retarded patients

Summary Routine chromosome analysis of two patients with severe mental retardation revealed two 45,D-,D-,t(DqDq)+karyotypes. With the aid of a Giemsa banding technique the translocation chromosomes were identified as a t(13q14q) and a t(14q15q).

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Zusammenfassung Eine Routine-Chromosomenanalyse von zwei Patienten mit geistiger Retardation zeigte zwei 45,D-,D-,t(DqDq)+-Karyotypen. Mit Hilfe einer Giemsamusterfärbung war es möglich, die respektiven Translokationschromosomen als t(13q14q) und t(14q15q) zu identifizieren.

     

Enrichment and characterization of marine anammox bacteria associated with global nitrogen gas production

Microbiological investigation of anaerobic ammonium oxidizing (anammox) bacteria has until now been restricted to wastewater species. The present study describes the enrichment and characterization of two marine Scalindua species, the anammox genus that dominates almost all natural habitats investigated so far. The species were enriched from a marine sediment in the Gullmar Fjord (Sweden) using a medium based on Red Sea salt. Anammox cells comprised about 90% of the enrichment culture after 10 months. The enriched Scalindua bacteria displayed all typical features known for anammox bacteria, including turnover of hydrazine, the presence of ladderane lipids, and a compartmentalized cellular ultrastructure. The Scalindua species also showed a nitrate-dependent use of formate, acetate and propionate, and performed a formate-dependent reduction of nitrate, Fe(III) and Mn(IV). This versatile metabolism may be the basis for the global distribution and substantial contribution of the marine Scalindua anammox bacteria to the nitrogen loss from oxygen-limited marine ecosystems.