Efficacy of sulfadoxine-pyrimethamine in Tanzania after two years as first-line drug for uncomplicated malaria: assessment protocol and implication for treatment policy strategies

Background

Early diagnosis and effective treatment with an appropriate drug form the main components of the World Health Organization's strategy to reduce malaria related mortality. The few available drugs might be safeguarded if combined with artesunate. The addition of artesunate to a standard antimalarial treatment substantially reduces treatment failure, recrudescence and gametocyte carriage.

Methods

During late 2004, the efficacy of artesunate (4 mg/kg. day, on days 0–2) plus sulfadoxine-pyrimethamine (25 mg/kg, on day 0) for the treatment of uncomplicated Plasmodium falciparum malaria was investigated in four sentinel areas in Sudan, with different malaria transmission (Damazin, Kassala, Kosti, and Malakal).

Results

Two hundreds and sixty-nine patients completed the 28-day follow-up. On day one, 60 (22.3%) patients were febrile and 15 (5.5%) patients were parasitaemic. On day three, all the patients were afebrile and aparasitaemic. While two patients (0.7%, Kassala) showed late Clinical and Parasitological Failures, the rest (99.3%) of the patients demonstrated Adequate Clinical and Parasitological Response. A gametocytaemia were detected during the follow-up in one patient (0.37%, Kassala). Adverse drug effects were detected in 32 (11.9%) patients

Conclusion

The study showed that AS plus SP is an effective, safe drug in the treatment of uncomplicated P. falciparum malaria in Sudan.     

From heart to mind. The urotensin II system and its evolving neurophysiological role

The discovery of novel biologically active peptides has led to an explosion in our understanding of the molecular mechanisms that underlie the regulation of sleep and wakefulness. Urotensin II (UII), a peptide originally isolated from fish and known for its strong cardiovascular effects in mammals, is another surprising candidate in the regulatory network of sleep. The UII receptor was found to be expressed by cholinergic neurons of laterodorsal and pedunculopontine tegmental nuclei, an area known to be of utmost importance for the on- and offset of rapid eye movement (REM) sleep. Recently, physiological data have provided further evidence that UII is indeed a modulator of REM sleep. The peptide directly excites cholinergic mesopontine neurons and increases the rate of REM sleep episodes. These new results and its emerging behavioral effects establish UII as a neurotransmitter/neuromodulator in mammals and should spark further interest into the neurobiological role of the peptide.     

A novel beta-peptidyl aminopeptidase (BapA) from strain 3-2W4 cleaves peptide bonds of synthetic beta-tri- and beta-dipeptides

A novel bacterial strain that was capable of growing on the beta-tripeptide H-betahVal-betahAla-betahLeu-OH as the sole carbon and nitrogen source was isolated from an enrichment culture. On the basis of physiological characterization, partial 16S rRNA sequencing, and fatty acid analysis, strain 3-2W4 was identified as a member of the family Sphingomonadaceae. Growth on the beta-tripeptide and the beta-dipeptide H-betahAla-betahLeu-OH was observed, and emerging metabolites were characterized. Small amounts of a persisting metabolite, the N-acetylated beta-dipeptide, were identified in both media. According to dissolved organic carbon measurements, 74 to 80% of the available carbon was dissimilated. The beta-peptide-degrading enzyme was purified from the crude cell extract of cells from strain 3-2W4 grown on complex medium. The enzyme was composed of two subunits, and the N-terminal sequences of both were determined. With this information, it was possible to identify the complete nucleotide sequence and to deduce the primary structure of the gene bapA. The gene encoded a beta-peptidyl aminopeptidase (BapA) of 402 amino acids that was synthesized as preprotein with a signal sequence of 29 amino acids. The enzyme was cleaved into two subunits (residues 30 to 278 and 279 to 402). It belonged to the N-terminal nucleophile (Ntn) hydrolase superfamily.     

A new type of peroxisomal acyl-coenzyme A synthetase from Arabidopsis thaliana has the catalytic capacity to activate biosynthetic precursors of jasmonic acid

Arabidopsis thaliana contains a large number of genes that encode carboxylic acid-activating enzymes, including nine long-chain fatty acyl-CoA synthetases, four 4-coumarate:CoA ligases (4CL), and 25 4CL-like proteins of unknown biochemical function. Because of their high structural and sequence similarity with bona fide 4CLs and their highly hydrophobic putative substrate-binding pockets, the 4CL-like proteins At4g05160 and At5g63380 were selected for detailed analysis. Following heterologous expression, the purified proteins were subjected to a large scale screen to identify their preferred in vitro substrates. This study uncovered a significant activity of At4g05160 with medium-chain fatty acids, medium-chain fatty acids carrying a phenyl substitution, long-chain fatty acids, as well as the jasmonic acid precursors 12-oxo-phytodienoic acid and 3-oxo-2-(2'-pentenyl)-cyclopentane-1-hexanoic acid. The closest homolog of At4g05160, namely At5g63380, showed high activity with long-chain fatty acids and 12-oxo-phytodienoic acid, the latter representing the most efficiently converted substrate. By using fluorescent-tagged variants, we demonstrated that both 4CL-like proteins are targeted to leaf peroxisomes. Collectively, these data demonstrate that At4g05160 and At5g63380 have the capacity to contribute to jasmonic acid biosynthesis by initiating the beta-oxidative chain shortening of its precursors.     

A novel type of detergent-resistant membranes may contribute to an early protein sorting event in epithelial cells

One sorting mechanism of apical and basolateral proteins in epithelial cells is based on their solubility profiles with Triton X-100. Nevertheless, apical proteins themselves are also segregated beyond the trans-Golgi network by virtue of their association or nonassociation with cholesterol/sphingolipid-rich microdomains (Jacob, R., and Naim, H. Y. (2001) Curr. Biol. 11, 1444-1450). Therefore, extractability with Triton X-100 does not constitute an absolute criterion of protein sorting. Here, we investigate the solubility patterns of apical and basolateral proteins with other detergents and demonstrate that the mild detergent Tween 20 is adequate to discriminate between apical and basolateral proteins during early stages in their biosynthesis. Although the mannose-rich forms of the apical proteins sucrase-isomaltase, lactase-phlorizin hydrolase, aminopeptidase N, and dipeptidylpeptidase IV reveal similar solubility profiles comprising soluble and nonsoluble fractions, the basolateral proteins, vesicular stomatitis virus G protein, major histocompatibility complex class I, and CD46 are entirely soluble with this detergent. The insoluble Tween 20 membranes are enriched in phosphatidylinositol and phosphatidylglycerol compatible with their synthesis in the endoplasmic reticulum and the existence of a novel class of detergent-resistant membranes. The association of the mannose-rich biosynthetic forms of the apical proteins, sucraseisomaltase, lactase-phlorizin hydrolase, aminopeptidase N, and dipeptidylpeptidase IV with the Tween 20-resistant membranes suggests an early polarized sorting mechanism prior to maturation in the Golgi apparatus.     

Role of ceramide in activation of stress-associated MAP kinases by minimally modified LDL in vascular smooth muscle cells

Interaction of oxidized low-density lipoprotein (LDL) with arterial smooth muscle cells (SMC) is believed to play a key role in the development of atherosclerosis. Depending on the extent of oxidation, apolipoproteins and/or lipids in the particle may be modified and thus lead to different cellular responses (e.g. proliferation or cell death). Here we report on the signaling effects of LDL, in which only the lipids were oxidized. This so-called minimally modified LDL (mmLDL) mainly activated components involved in stress response and apoptotic cell death including p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase/stress-activated protein kinase (JNK) as well as neutral and acid sphingomyelinase. In contrast, proliferative signaling elements such as extracellular regulated kinase, AKT-kinase and phospho-BAD seem to play a minor role as they were only slightly stimulated by mmLDL. Ceramide, the hydrolysis product of sphingomyelin, seems to be a key mediator as it mimics mmLDL by inducing activation of the same signaling components. Moreover, mmLDL- and ceramide-associated effects on apoptotic protein kinases were abolished by NB6, a specific inhibitor of acid sphingomyelinase. Thus, acid sphingomyelinase is very likely to be primarily responsible for triggering intracellular signal transduction in SMC after exposure to mmLDL via formation of ceramide by an autocatalytic mechanism.     

Nonmuscle myosin heavy-chain gene MYH14 is expressed in cochlea and mutated in patients affected by autosomal dominant hearing impairment (DFNA4)

Myosins have been implicated in various motile processes, including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Different members of the myosin superfamily are responsible for syndromic and nonsyndromic hearing impairment in both humans and mice. MYH14 encodes one of the heavy chains of the class II nonmuscle myosins, and it is localized within the autosomal dominant hearing impairment (DFNA4) critical region. After demonstrating that MYH14 is highly expressed in mouse cochlea, we performed a mutational screening in a large series of 300 hearing-impaired patients from Italy, Spain, and Belgium and in a German kindred linked to DFNA4. This study allowed us to identify a nonsense and two missense mutations in large pedigrees, linked to DFNA4, as well as a de novo allele in a sporadic case. Absence of these mutations in healthy individuals was tested in 200 control individuals. These findings clearly demonstrate the role of MYH14 in causing autosomal dominant hearing loss and further confirm the crucial role of the myosin superfamily in auditive functions.     

Bacterial beta-peptidyl aminopeptidases with unique substrate specificities for beta-oligopeptides and mixed beta,alpha-oligopeptides

We previously discovered that BapA, a bacterial beta-peptidyl aminopeptidase, is able to hydrolyze two otherwise metabolically inert beta-peptides [Geueke B, Namoto K, Seebach D and Kohler H-PE (2005) J Bacteriol 187, 5910-5917]. Here, we describe the purification and characterization of two distinct bacterial beta-peptidyl aminopeptidases that originated from different environmental isolates. Both bapA genes encode a preprotein with a signal sequence and were flanked by ORFs that code for enzymes with similar predicted functions. To form the active enzymes, which had an (alphabeta)(4) quaternary structure, the preproteins needed to be cleaved into two subunits. The two beta-peptidyl aminopeptidases had 86% amino acid sequence identity, hydrolyzed a variety of beta-peptides and mixed beta/alpha-peptides, and exhibited unique substrate specificities. The prerequisite for peptides being accepted as substrates was the presence of a beta-amino acid at the N-terminus; peptide substrates with an N-terminal alpha-amino acid were not hydrolyzed at all. Both enzymes cleaved the peptide bond between the N-terminal beta-amino acid and the amino acid at the second position of tripeptidic substrates of the general structure H-betahXaa-Ile-betahTyr-OH according to the following preferences with regard to the side chain of the N-terminal beta-amino acid: aliphatic and aromatic > OH-containing > hydrogen, basic and polar. Experiments with the tripeptides H-d-betahVal-Ile-betahTyr-OH and H-betahVal-Ile-betahTyr-OH demonstrated that the two BapA enzymes preferred the peptide with the l-configuration of the N-terminal beta-homovaline residue as a substrate.