Rotifera from north and northeast Anatolia (Turkey)

Samples from 21 freshwater sites in Turkey yielded 91 different species of Rotifera, 42 of which are new to the Turkish fauna. Lepadella costatoides n. sp. is described and L. costata Wulfert is redescribed. L. christineae Koste is synonymised with L. quinquecostata (Lucks). Remarks on the intraspecific variability of some species of Lecane are given. L. pomiformis Edmondson is added to the synonymy of L. pyriformis (Daday). The synonymy of the latter with L. paraclosterocerca Pennak is confirmed.     

Combination of AT-101/cisplatin overcomes chemoresistance by inducing apoptosis and modulating epigenetics in human ovarian cancer cells

We investigated the effects of AT-101/cisplatin combination treatment on the expression levels of apoptotic proteins and epigenetic events such as DNA methyltransferase (DNMT) and histone deacetylase (HDAC) enzyme activities in OVCAR-3 and MDAH-2774 ovarian cancer cells. XTT cell viability assay was used to evaluate cytotoxicity. For showing apoptosis, both DNA Fragmentation and caspase 3/7 activity measurements were performed. The expression levels of apoptotic proteins were assessed by human apoptosis antibody array. DNMT and HDAC activities were evaluated by ELISA assay and mRNA levels of DNMT1 and HDAC1 genes were quantified by qRT-PCR. Combination of AT-101/cisplatin resulted in strong synergistic cytotoxicity and apoptosis in human ovarian cancer cells. Combination treatment reduced some pivotal anti-apoptotic proteins such as Bcl-2, HIF-1A, cIAP-1, XIAP in OVCAR-3 cells, whereas p21, Bcl-2, cIAP-1, HSP27, Clusterin and XIAP in MDAH-2774 cells. Among the pro-apoptotic proteins, Bad, Bax, Fas, phospho-p53 (S46), Cleaved caspase-3, SMAC/Diablo, TNFR1 and Cytochrome c were induced in OVCAR-3 cells, whereas, Bax, TRAILR2, FADD, p27, phospho-p53 (S46), Cleaved caspase-3, Cytochrome c, SMAC/Diablo and TNFR1 were induced in MDAH-2774 cells. Combination treatment also inhibited both DNMT and HDAC activities and also mRNA levels in both ovarian cancer cells. AT-101 exhibits great potential in sensitization of human ovarian cancer cells to cisplatin treatment in vitro, suggesting that the combination of AT-101 with cisplatin may hold great promise for development as a novel chemotherapeutic approach to overcome platinum-resistance in human ovarian cancer.     

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.     

Phospholipase C inhibitors and prostaglandins differentially regulate phosphatidylcholine synthesis in rat renal papilla. Evidence of compartmental regulation of CTP:phosphocholine cytidylyltransferase and CDP-choline:1,2-diacylglycerol cholinephosphotransferase

Phosphatidylcholine (PC) is the most abundant phospholipid in mammalian cell membranes. Several lines of evidence support that PC homeostasis is preserved by the equilibrium between PC biosynthetic enzymes and phospholipases catabolic activities. We have previously shown that papillary synthesis of PC depends on prostaglandins (PGs) that modulate biosynthetic enzymes. In papillary tissue, under bradikynin stimulus, arachidonic acid (AA) mobilization (the substrate for PG synthesis) requires a previous phospholipase C (PLC) activation. Thus, in the present work, we study the possible involvement of PLC in PC biosynthesis and its relationship with PG biosynthetic pathway on the maintenance of phospholipid renewal in papillary membranes; we also evaluated the relevance of CDP-choline pathway enzymes compartmentalization. To this end, neomycin, U-73122 and dibutiryl cyclic AMP, reported as PLC inhibitors, were used to study PC synthesis in rat renal papilla. All the PLC inhibitors assayed impaired PC synthesis. PG synthesis was also blocked by PLC inhibitors without affecting cyclooxygenase activity, indicating a metabolic connection between both pathways. However, we found that PC biosynthesis decrease in the presence of PLC inhibitors was not a consequence of PG decreased synthesis, suggesting that basal PLC activity and PGs exert their effect on different targets of PC biosynthetic pathway. The study of PC biosynthetic enzymes showed that PLC inhibitors affect CTP:phosphocholine cytidylyltransferase (CCT) activity while PGD(2) operates on CDP-choline:1,2-diacylglycerol cholinephosphotransferase (CPT), both activities associated to papillary enriched-nuclei fraction. The present results suggest that renal papillary PC synthesis is a highly regulated process under basal conditions. Such regulation might occur at least at two different levels of the CDP-choline pathway: on the one hand, PLC operates on CCT activity; on the other, while PGs regulate CPT activity.     

Increased concentration of polyvalent phospholipids in the adsorption domain of a charged protein

We studied the adsorption of a charged protein onto an oppositely charged membrane, composed of mobile phospholipids of differing valence, using a statistical-thermodynamical approach. A two-block model was employed, one block corresponding to the protein-affected region on the membrane, referred to as the adsorption domain, and the other to the unaffected remainder of the membrane. We calculated the protein-induced lipid rearrangement in the adsorption domain as arising from the interplay between the electrostatic interactions in the system and the mixing entropy of the lipids. Equating the electrochemical potentials of the lipids in the two blocks yields an expression for the relations among the various lipid fractions in the adsorption domain, indicating a sensitive dependence of lipid fraction on valence. This expression is a result of the two-block picture but does not depend on further details of the protein-membrane interaction. We subsequently calculated the lipid fractions themselves using the Poisson-Boltzmann theory. We examined the dependence of lipid enrichment, i.e., the ratio between the lipid fractions inside and outside the adsorption domain, on various parameters such as ionic strength and lipid valence. Maximum enrichment was found for lipid valence in the range between -3 and -4 in physiological conditions. Our results are in qualitative agreement with recent experimental studies on the interactions between peptides having a domain of basic residues and membranes containing a small fraction of the polyvalent phosphatidylinositol 4,5-bisphosphate (PIP2). This study provides theoretical support for the suggestion that proteins adsorbed onto membranes through a cluster of basic residues may sequester PIP2 and other polyvalent lipids.     

Interaction of bacteriophage lambda with its cell surface receptor: an in vitro study of binding of the viral tail protein gpJ to LamB (Maltoporin)

The cell surface receptor for bacteriophage Lambda is LamB (maltoporin). Responsible for phage binding to LamB is the C-terminal part, gpJ, of phage tail protein J. To study the interaction between LamB and gpJ, a chimera protein composed of maltose binding protein (MBP or MalE) connected to the C-terminal part of J (gpJ, amino acids 684-1131) of phage tail protein J of bacteriophage Lambda was expressed in Escherichia coli and purified to homogeneity. The interaction of the MBP-gpJ chimera protein with reconstituted LamB and its mutants LamB Y118G and the loop deletion mutant LamB Delta4+Delta6+Delta9v was studied using planar lipid bilayer membranes on a single-channel and multichannel level. Titration with the MBP-gpJ chimera blocked completely the ion current through reconstituted LamB when it was added to the cis side, the extracellular side of LamB with a half-saturation constant of approximately 6 nM in 1 M KCl. Control experiments with LamB Delta4+Delta6+Delta9v from which all major external loops had been removed showed similar blocking, whereas MBP alone caused no visible effect. Direct conductance measurement with His(6)-gpJ that contained a hexahistidyl tag (His(6) tag) at the N-terminal end of the protein for easy purification revealed no blocking of the ion current, requiring other measurements for the binding constant. However, when maltoporin was preincubated with His-gpJ, MBP-gpJ could not block the channel, which indicated that also His(6)-gpJ bound to the channel. High-molecular mass bands on SDS-PAGE and Western blots, confirming the planar lipid bilayer experiment results, also demonstrated stable complex formation between His(6)-gpJ and LamB or LamB mutants. The results revealed that phage Lambda binding includes not only the extracellular loops.     

Elevated pontine and putamenal GABA levels in mild-moderate Parkinson disease detected by 7 tesla proton MRS

Background

Parkinson disease (PD) is characterized by the degeneration of nigrostriatal dopaminergic neurons. However, postmortem evidence indicates that the pathology of lower brainstem regions, such as the pons and medulla, precedes nigral involvement. Consistently, pontomedullary damage was implicated by structural and PET imaging in early PD. Neurochemical correlates of this early pathological involvement in PD are unknown.

Methodology/Principal Finding

To map biochemical alterations in the brains of individuals with mild-moderate PD we quantified neurochemical profiles of the pons, putamen and substantia nigra by 7 tesla (T) proton magnetic resonance spectroscopy. Thirteen individuals with idiopathic PD (Hoehn & Yahr stage 2) and 12 age- and gender-matched healthy volunteers participated in the study. γ-Aminobutyric acid (GABA) concentrations in the pons and putamen were significantly higher in patients (N = 11, off medications) than controls (N = 11, p<0.001 for pons and p<0.05 for putamen). The GABA elevation was more pronounced in the pons (64%) than in the putamen (32%). No other neurochemical differences were observed between patients and controls.

Conclusion/Significance

The GABA elevation in the putamen is consistent with prior postmortem findings in patients with PD, as well as with in vivo observations in a rodent model of PD, while the GABA finding in the pons is novel. The more significant GABA elevation in the pons relative to the putamen is consistent with earlier pathological involvement of the lower brainstem. This study provides in vivo evidence for an alteration in the GABAergic tone in the lower brainstem and striatum in early-moderate PD, which may underlie disease pathogenesis and may provide a biomarker for disease staging.     

Persistence of Borrelia burgdorferi in rhesus macaques following antibiotic treatment of disseminated infection

The persistence of symptoms in Lyme disease patients following antibiotic therapy, and their causes, continue to be a matter of intense controversy. The studies presented here explore antibiotic efficacy using nonhuman primates. Rhesus macaques were infected with B. burgdorferi and a portion received aggressive antibiotic therapy 4-6 months later. Multiple methods were utilized for detection of residual organisms, including the feeding of lab-reared ticks on monkeys (xenodiagnosis), culture, immunofluorescence and PCR. Antibody responses to the B. burgdorferi-specific C6 diagnostic peptide were measured longitudinally and declined in all treated animals. B. burgdorferi antigen, DNA and RNA were detected in the tissues of treated animals. Finally, small numbers of intact spirochetes were recovered by xenodiagnosis from treated monkeys. These results demonstrate that B. burgdorferi can withstand antibiotic treatment, administered post-dissemination, in a primate host. Though B. burgdorferi is not known to possess resistance mechanisms and is susceptible to the standard antibiotics (doxycycline, ceftriaxone) in vitro, it appears to become tolerant post-dissemination in the primate host. This finding raises important questions about the pathogenicity of antibiotic-tolerant persisters and whether or not they can contribute to symptoms post-treatment.     

Role of endogenous brain-derived neurotrophic factor and sortilin in B cell survival

Brain-derived neurotrophic factor (BDNF), a major neuronal growth factor, is also known to exert an antiapoptotic effect in myeloma cells. Whereas BDNF secretion was described in B lymphocytes, the ability of B cells to produce sortilin, its transport protein, was not previously reported. We studied BDNF production and the expression of its receptors, tyrosine protein kinase receptor B and p75 neurotrophin receptor in the human pre-B, mature, and plasmacytic malignant B cell lines under normal and stress culture conditions (serum deprivation, Fas activation, or their combination). BDNF secretion was enhanced by serum deprivation and exerted an antiapoptotic effect, as demonstrated by neutralization experiments with antagonistic Ab. The precursor form, pro-BDNF, also secreted by B cells, decreases under stress conditions in contrast to BDNF production. Stress conditions induced the membranous expression of p75 neurotrophin receptor and tyrosine protein kinase receptor B, maximal in mature B cells, contrasting with the sequestration of both receptors in normal culture. By blocking Ab and small interfering RNA, we evidenced that BDNF production and its survival function are depending on sortilin, a protein regulating neurotrophin transport in neurons, which was not previously described in B cells. Therefore, in mature B cell lines, an autocrine BDNF production is up-regulated by stress culture conditions and exerts a modulation of apoptosis through the sortilin pathway. This could be of importance to elucidate certain drug resistances of malignant B cells. In addition, primary B lymphocytes contained sortilin and produced BDNF after mitogenic activation, which suggests that sortilin and BDNF might be implicated in the survival and activation of normal B cells also.