Stability in bcc transition metals: Madelung and band-energy effects due to alloying.

The phase stability of group VB (V, Nb, and Ta) transition metals is explored by first-principles electronic-structure calculations. Alloying with a small amount of a neighboring metal can either stabilize or destabilize the body-centered-cubic phase relative to low-symmetry rhombohedral phases. We show that band-structure effects determine phase stability when a particular group VB metal is alloyed with its nearest neighbors within the same d-transition series. In this case, the neighbor with less (to the left) and more (to the right) d electrons destabilize and stabilize bcc, respectively. When alloying with neighbors of higher d-transition series, electrostatic Madelung energy dominates and stabilizes the body-centered-cubic phase. This surprising prediction invalidates current understanding of simple d-electron bonding that dictates high-symmetry cubic and hexagonal phases.

Immunolocalization of Taenia solium gap junction innexins.

In previous studies, ultrastructural observations revealed a large number of gap junctions (GJs) in the neck and immature proglottid tissues of Taenia solium tapeworms. In these helminths, cytoplasmic glycogen sacs are connected by numerous discrete GJs to other cells throughout the maturing strobilar tissue. Discontinuous sucrose gradients were used to purify membrane fractions containing GJs, which were identified by ultrastructural analysis. A trans-membrane peptide sequence from a highly conserved innexin region was used to construct a 20-amino acid synthetic peptide and used to raise polyclonal antibodies in rabbits that recognized both a 55 and a 67 kDa protein in a Western blot of the GJ-enriched pellet. Immunohistochemistry of larval and adult worm sections incubated with antiserum to the synthetic peptide and a secondary anti-rabbit IgG bound to fluorescein, revealed strong binding to the tegumentary surface of the worm, as well as patchy fluorescent areas in the parenchyma. The results indicate that both the tegument of cysticerci and adult T. solium contain innexin-rich membranes, which may function as a tegumentary transport system for small molecules.

Prazosin blocks the glutamatergic effects of N-methyl-D-aspartic acid on lordosis behavior and luteinizing hormone secretion in the estrogen-primed female rat.

We have observed that intracerebroventricular (icv) injection of selective N-methyl-D-aspartic acid (NMDA)-type glutamatergic receptor antagonists inhibits lordosis in ovariectomized (OVX), estrogen-primed rats receiving progesterone or luteinizing hormone-releasing hormone (LHRH). When NMDA was injected into OVX estrogen-primed rats, it induced a significant increase in lordosis. The interaction between LHRH and glutamate was previously explored by us and another groups. The noradrenergic systems have a functional role in the regulation of LHRH release. The purpose of the present study was to explore the interaction between glutamatergic and noradrenergic transmission. The action of prazosin, an alpha1- and alpha2b-noradrenergic antagonist, was studied here by injecting it icv (1.75 and 3.5 microg/6 microL) prior to NMDA administration (1 microg/2 microL) in OVX estrogen-primed Sprague-Dawley rats (240-270 g). Rats manually restrained were injected over a period of 2 min, and tested 1.5 h later. The enhancing effect induced by NMDA on the lordosis/mount ratio at high doses (67.06 +/- 3.28, N = 28) when compared to saline controls (6 and 2 microL, 16.59 +/- 3.20, N = 27) was abolished by prazosin administration (17.04 +/- 5.52, N = 17, and 9.33 +/- 3.21, N = 20, P < 0.001 for both doses). Plasma LH levels decreased significantly only with the higher dose of prazosin (1.99 +/- 0.24 ng/mL, N = 18, compared to saline-NMDA effect, 5.96 +/- 2.01 ng/mL, N = 13, P < 0.05). Behavioral effects seem to be more sensitive to the alpha-blockade than hormonal effects. These findings strongly suggest that the facilitatory effects of NMDA on both lordosis and LH secretion in this model are mediated by alpha-noradrenergic transmission.

Phonon and magnetic structure in δ-plutonium from density-functional theory.

We present phonon properties of plutonium metal obtained from a combination of density-functional-theory (DFT) electronic structure and the recently developed compressive sensing lattice dynamics (CSLD). The CSLD model is here trained on DFT total energies of several hundreds of quasi-random atomic configurations for best possible accuracy of the phonon properties. The calculated phonon dispersions compare better with experiment than earlier results obtained from dynamical mean-field theory. The density-functional model of the electronic structure consists of disordered magnetic moments with all relativistic effects and explicit orbital-orbital correlations. The magnetic disorder is approximated in two ways: (i) a special quasi-random structure and (ii) the disordered-local-moment method within the coherent potential approximation. Magnetism in plutonium has been debated intensely, but the present magnetic approach for plutonium is validated by the close agreement between the predicted magnetic form factor and that of recent neutron-scattering experiments.

Mammary gland type I iodothyronine deiodinase is encoded by a short messenger ribonucleic acid.

Lactating rat mammary gland expresses a deiodinating activity that, on the basis of kinetic characteristics, corresponds to the so-called 5'-deiodinase type I (D1). In the present study we amplified and sequenced several D1 complementary DNA (cDNA) fragments from rat lactating mammary gland. The mammary cDNA was found to be identical to the previously reported rat liver cDNA in the coding region, but 465 nucleotides shorter on its 3'-untranslated region, suggesting that the D1 is the same in both tissues. D1 messenger RNA (mRNA) was also detected by reverse transcriptase-PCR in mammary glands from puberal and late pregnant rats, but not in virgin animals. Densitometric analysis showed a close and direct correlation between mRNA content and enzyme specific activity in mammary gland. Our results also show that rat liver contains both D1 mRNA forms and that the large form may respond to the thyroid status. These data suggest a differential and organ-specific expression of these mRNA forms, which could play a role in the functional regulation of D1 activity.

Alternative splicing of the Schistosoma mansoni gene encoding a homologue of epidermal growth factor receptor.

The complete coding DNA for a Schistosoma mansoni homologue of the epidermal growth factor receptor (SER) was characterized from cDNA clones obtained by homology to the tyrosine kinase domain of erbB. The DNA sequence predicts a 200-kDa translation product that contains a secretory leader, a cysteine-rich extracellular domain, a hydrophobic transmembrane sequence, and an intracellular tyrosine kinase domain. The SER transcript is present in cercariae and adult schistosomes. In addition to SER transcripts, schistosomes produce at least 3 variant transcripts encoding truncated SER products that include the secretory leader and a small portion of the extracellular domain followed by short sequences of unrelated, C-terminal amino acids. Based on these sequences, 2 of the variant mRNAs (class 2 and 5) appear to encode soluble, secreted proteins while one (class 4) encodes an SER variant protein with a hydrophobic C-terminus that may serve as a membrane anchor. Class 2 SER variant transcripts are present at levels comparable to SER transcripts in adult worms but are not detected in cercariae. Class 4 and 5 SER variant transcripts are also found within adult worms but at lower levels. Genomic cloning and characterization demonstrate that the variant SER transcripts arise through alternative splicing of the SER gene.

Paramyosin is the Schistosoma mansoni (Trematoda) homologue of antigen B from Taenia solium (Cestoda).

Antigen B, a major antigen of the cestode parasite Taenia solium, has been purified and a portion of amino acid sequence obtained. Paramyosin of the trematode parasite Schistosoma mansoni, an immunogenic protein that has shown promise as a vaccine candidate, has several biochemical and immunological properties in common with antigen B. A full-length cDNA clone of S. mansoni paramyosin has been obtained and the predicted translation product contains a sequence that is highly homologous to the sequence obtained for antigen B. The predicted amino acid composition and isolectric point of paramyosin are nearly identical to those established for antigen B. Recombinant S. mansoni paramyosin, expressed in Escherichia coli as a fusion protein with beta-galactosidase, was recognized by antisera against T. solium antigen B. We conclude from these results that S. mansoni paramyosin and T. solium antigen B are homologous proteins. Since S. mansoni paramyosin is thought to be a muscle protein and T. solium antigen B a secreted glycoprotein with anti-complement activity, this conclusion raises some interesting questions regarding the role of this class of proteins in the host-parasite relationship.

Cloning, characterization and functional expression of a cyclophilin of Entamoeba histolytica.

Full-length Entamoeba histolytica cyclophilin gene (EhCyp) was isolated, characterized and recombinantly expressed in bacterial cells. The deduced amino acid sequence of EhCyp shows 60-70% identity with cyclophilins from other organisms and has conserved the cyclophilin signature motifs and residues involved in cyclosporin A binding. Upstream of the 501 bp open reading frame of EhCyp, sequences resembling the putative consensus E. histolytica CE1, CE2 and CE3 regulatory elements were found. Northern blot assays revealed a single transcript of 0.63 kb. The transcription start was determined by primer extension at position -13 relative to the initial ATG codon. Cyclosporin A binding and peptidyl-proplyl cis-trans isomerase activities characteristic of cyclophilin were detected in soluble extracts of E. histolytica trophozoites and in the recombinant protein. In both cases, the isomerase activity was inhibited by nanomolar concentrations of cyclosporin A. Treatment of cultured trophozoites with cyclosporin A decreased their proliferation with a 50% inhibition value of 1 microg/ml and was lethal in doses over 50 microg/ml.

Cloning and sequencing of two actin genes from Taenia solium (Cestoda).

Genomic and cDNA actin clones were isolated from Taenia solium gene libraries. The actin genes are interrupted by intervening sequences. Protein coding regions of both genes predict the same amino acid sequence. cDNA sequence data indicate that at least one gene is expressed at the larval stage. Results from Northern and Western blots showed that T. solium expresses an actin transcript of about 1,400 bases and a protein of 45,000 Da.

Potential role of the cannabinoid receptor CB1 in rapid eye movement sleep rebound.

Sleep is an unavoidable activity of the brain. The delay of the time to sleep (sleep deprivation), induces an increase of slow-wave sleep and rapid-eye-movement (REM) sleep (rebound) once the subject is allowed to sleep. This drive to sleep has been hypothesized to be dependent on the accumulation of sleep-inducing molecules and on the high expression of these molecule receptors. In this study we selectively deprived rats of REM sleep for 24 h by using the flowerpot technique. One group deprived of REM sleep was treated with SR141716A, a cannabinoid receptor 1 (CB1) receptor antagonist and then allowed to sleep for the next 4 h. Two other groups were killed, one immediately after the REM sleep deprivation period and the other after 2 h of REM sleep rebound (REM sleep deprivation plus 2 h of rebound). In both groups we determined the expression of the CB1 receptor and its mRNA. Results indicated that SR141716A prevents REM sleep rebound and REM sleep deprivation does not modify the expression of the CB1 protein or mRNA. However, REM sleep deprivation plus 2 h of sleep rebound increased the CB1 receptor protein and, slightly but significantly, decreased mRNA expression. These results suggest that endocannabinoids may be participating in the expression of REM sleep rebound.

Sleep modulates cannabinoid receptor 1 expression in the pons of rats.

Endocannabinoids seem to play a role in the modulation of alertness. Therefore, we measured cannabinoid receptor 1 (CB1R) protein by Western blot and messenger RNA (mRNA) by reverse transcription-polymerase chain reaction in the pons of rats across the 24-h period. We performed evaluations every 4 h beginning at 09:00 h. Rats were under a controlled light/dark cycle 12:12 (lights on at 08:00 h). Our data suggest that the expression of CB1R gene depends on diurnal variations, with maximum expression at 13:00 h for protein and 21:00 h for mRNA, and minimum expression at 01:00 and 09:00 h, respectively. We also analyzed CB1R protein and mRNA levels in the pons of rats deprived of total sleep for 24 h and in rats with a 24-h period of sleep deprivation plus a 2-h period of sleep rebound. Unlike sleep deprivation, sleep rebound significantly increased CB1R protein while decreasing mRNA. Despite the fact that we used gentle manipulation to deprive the animals of sleep, there may be a potential influence of stress on this effect, too. However, these facts suggest that CB1R gene expression is modulated by the light/dark cycle and by sleep.

Purification and ultrastructural localization of surface glycoproteins of Taenia solium (Cestoda) cysticerci.

A glycoprotein-enriched fraction was obtained by Concanavalin A-Sepharose 4B affinity chromatography from a crude extract of T. solium cysticerci. The six most prominent glycoproteins with molecular sizes of 180, 103, 96, 68, 55 and 45 kDa were purified by electro-elution from polyacrylamide gel slices. Ultrastructural localization assays using hyperimmune rabbit sera to each glycoprotein, demonstrated their presence on the tegumentary surface of the bladder wall of T. solium cysticerci. Similar studies showed that the 180 kDa glycoprotein is also present on the surface of the T. solium and T. saginata adult worms, as well as in T. saginata, T. pisiformis and T. crassiceps cysticerci. The 55 kDa glycoprotein, which is one of the most abundant on the cyst surface, was found to correspond to the heavy chain of pig IgG by Western blotting.

Cloning, expression and characterisation of a recombinant triosephosphate isomerase from Taenia solium.

We isolated and characterised the cDNA that encodes the glycolytic enzyme, triosephosphate isomerase from Taenia solium. A 450 bp DNA fragment was obtained by the polymerase chain reaction using a cDNA from larval stage as template and degenerate oligonucleotides designed from conserved polypeptide sequences from TPIs of several organisms. The fragment was used to screen a T. solium larval stage cDNA library. The isolated cDNA, encoding a protein of 250 amino acids shares 44.8-59.6% positional identity with other known TPIs, in which the catalytic enzyme residues were conserved. The complete coding sequence of the T. solium TPI cDNA was cloned into the expression vector pRSET and expressed as a fusion protein with an N-terminal tail of six histidine residues. The catalytic activity of the purified protein was similar to other TPI enzymes. Northern and Southern blot analysis suggest that in T. solium, single gene exists for triosephosphate isomerase and that the gene is expressed in all stages of the parasite.

Comparison of sexual dysfunction in male schizophrenic patients maintained on treatment with classical antipsychotics versus clozapine.

BACKGROUND: Antipsychotic treatment is frequently associated with sexual dysfunction. The objective of the present study was to evaluate and compare sexual function and behavior in male schizophrenic patients who regularly take either classical neuroleptic drugs or the prototypical atypical antipsychotic agent, clozapine. METHOD: Participants included 60 schizophrenic male patients (DSM-IV criteria); 30 maintained on treatment with classical antipsychotics and 30 on treatment with clozapine. The patients were evaluated with a detailed 18-item sexual function questionnaire. RESULTS: Both groups reported sexual dysfunction, although scores were significantly higher, indicating better functioning, in the clozapine-treated group in the domains of orgasmic function (number of orgasms per month, p = .037; frequency of orgasm during sex, p = .046), enjoyment of sex (p = .013), and sexual satisfaction (p = .0004). Equivocal results were obtained for the desire parameters. CONCLUSION: Maintenance therapy with the atypical neuroleptic clozapine may be associated with a lesser degree of sexual dysfunction than the classical antipsychotics in male outpatients with chronic schizophrenia.

Melatonin blocks in vitro generation of prostaglandin by the uterus and hypothalamus.

The effects of melatonin on the motility (isometric tension developed and contractile frequency) of uterine horns isolated from ovariectomized rats as well as on the mechanical responsiveness to added oxytocin or prostaglandin F2 alpha (PGF2 alpha) were explored. The pineal indole (10(-6) M or higher) depressed significantly the spontaneous motility of the uterus and reduced the responses evoked by oxytocin but not those evoked by PGF2 alpha. Melatonin was also tested on the prostaglandin (PG) release into the suspending media from either uterine horns from spayed rats or bovine medial basal hypothalamic (MBH) explants. Melatonin (10(-3) M) diminished the output from the uterus or the MBH of both PGE and PGF-"like material". Similarities between the effects of melatonin and indomethacin as well as the possible physiological relevance of the present findings are discussed.

Immunolocalization of a human cementoblastoma-conditioned medium-derived protein.

Little is known about the molecular mechanisms that regulate the cementogenesis process, because specific cementum markers are not yet available. To investigate whether a cementoblastoma-conditioned medium-derived protein (CP) could be useful as a cementum biological marker, we studied its expression and distribution in human periodontal tissues, human periodontal ligament, alveolar bone, and cementoblastoma-derived cells. In human periodontal tissues, immunoreactivity to anti-CP was observed throughout the cementoid phase of acellular and cellular cementum, cementoblasts, cementocytes, cells located in the endosteal spaces of human alveolar bone, and in cells in the periodontal ligament located near the blood vessels. Immunopurified CP promoted cell attachment on human periodontal ligament, alveolar bone-derived cells, and gingival fibroblasts. A monoclonal antibody against bovine cementum attachment protein (CAP) cross-reacted with CP. These findings indicate that CP identifies potential cementoblast progenitor cells, is immunologically related to CAP species, and serves as a biological marker for cementum.

Protein uptake by cysticerci of Taenia crassiceps.

The internalization of host macromolecules to the vesicular fluid of T. crassiceps cysticerci was studied in vitro. Uptake of purified class G immunoglobulin was not significantly affected by the specificity of its antigen-recognition site and bovine serum albumin was internalized at a similar rate. Internalization was inhibited at low temperature, being optimal at 37 degrees C and saturation was accomplished only at a protein concentration in the culture medium over 12 mg/ml which is close to the physiological concentration of serum proteins in the host. Morphological studies using markers for adsorptive endocytosis allowed visualization of endocytic vesicles and tracking of their movement across the bladder wall tissue. Degradation of internalized proteins was observed at longer times of incubation, suggesting that proteins are later processed and that degraded host macromolecules can be nutrients for cysticerci. Quantification of this capability of internalization suggests that it might play a role in the in vivo removal of potentially damaging host macromolecules, such as antibodies or complement factors, from the host-parasite interface.

Regulation of Brucella virulence by the two-component system BvrR/BvrS.

The Brucella BvrR/BvrS two-component regulatory system is highly similar to the regulatory and sensory proteins of Sinorhizobium and Agrobacterium necessary for endosymbiosis and pathogenicity in plants, and very similar to a putative system present in the animal pathogen Bartonella. Mutations in the bvrR or bvrS genes hamper the penetration of B. abortus in non-phagocytic cells and impairs intracellular trafficking and virulence. In contrast to virulent Brucella, BvrR/BvrS mutants do not recruit small GTPases of the Rho subfamily required for actin polymerization and penetration to cells. Dysfunction of the BvrR/BvrS system alters the outer membrane permeability, the expression of several group 3 outer membrane proteins and the pattern of lipid A acylation. Constructs of virulent B. abortus chimeras containing heterologous LPS from the bvrS(-) mutant demonstrated an altered permeability to cationic peptides similar to that of the BvrR/BvrS mutants. We hypothesize that the Brucella BvrR/BvrS is a system devoted to the homeostasis of the outer membrane and, therefore in the interface for cell invasion and mounting the required structures for intracellular parasitism.

Efficacy of ophthalmic solutions to detach adhering Pseudomonas aeruginosa from contact lenses.

PURPOSE: To compare the efficacies of two all-in-one contact lens (CL) cleaning solutions and a detergent mixture on the detachment of a pathogenic bacterium adhering to two types of contact lenses in the absence and presence of a tear film. METHODS: Bacterial-detachment studies were carried out in a parallel-plate flow chamber. Rigid gas permeable (RGP) CLs with and without a tear film were fixed on the bottom plate of the flow chamber. After adhesion of Pseudomonas aeruginosa no. 3, bacterial detachment was stimulated by perfusing the system either with an all-in-one CL-cleaning solution, for soft contact lenses (SCL solution) and for rigid lenses (RCL solution), or with a detergent mixture of 0.25% (wt/vol) sodium lauryl sulfate (SLS) and 0.2% sodium methyl cocoyl taurate (Tauranol). In addition, the all-in-one RCL-cleaning solution supplemented with 0.025% (wt/vol) SLS and 0.02% (wt/vol) Tauranol was evaluated. A surface physical-chemical analysis of the lenses before and after application of the solutions was done to determine whether remnants of the ophthalmic solutions or detergents could be found adsorbed to the CL surfaces. RESULTS: Both all-in-one CL-cleaning solutions stimulated minor bacterial detachment from CL surfaces with or without a tear film. The SLS/Tauranol detergent mixture, however, removed < or = 95% of the adhering P. aeruginosa cells, whereas the RCL-cleaning solution supplemented with detergents also stimulated significant detachment. Surface physical-chemical analysis clearly demonstrated the presence of a tear film on the CL surfaces, but remnants neither of the ophthalmic solutions nor of the detergents could be found. CONCLUSION: Ophthalmic solutions are not effective in stimulating detachment of adhering bacteria from CL surfaces. Supplementing of an all-in-one CL-cleaning solution with only small amounts of detergents yielded a solution much more effective in stimulating bacterial detachment while leaving no detectable remnants of the ophthalmic solution or of the detergents on the CL surfaces.

Characterization of glutathione S-transferase of Taenia solium.

A Taenia solium glutathione-S-transferase fraction (SGSTF) was isolated from a metacestode crude extract by affinity chromatography on reduced glutathione (GSH)-sepharose. The purified fraction displayed a specific glutathione S-transferase (GST) activity of 2.8 micromol/min/mg and glutathione peroxidase selenium-independent activity of 0.22 micromol/min/mg. Enzymatic characterization of the fraction suggested that the activity was closer to the mammalian mu-class GSTs. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel filtration, and enzyme activity analysis showed that the fraction was composed of a major band of Mr = 26 kd and that the active enzyme was dimeric. Immunohistochemical studies using specific antibodies against the major 26-kd band of the SGSTF indicated that GST protein was present in the tegument, parenchyma, protonephridial, and tegumentary cytons of the T. solium metacestode. Antibodies generated against the SGSTF tested in western blot showed cross-reactivity against GSTs purified from Taenia saginata, T. taeniaeformis, and T. crassiceps, but did not react with GSTs from Schistosoma mansoni, or mice, rabbit, and pig liver tissue. Furthermore, immunization of mice with SGSTF reduced the metacestode burden up to 74.2%. Our findings argue in favor of GST having an important role in the survival of T. solium in its hosts.