Effect of somatostatin on gastrointestinal contractility in Schistosoma mansoni infected mice

Schistosoma mansoni infection induces severe gastrointestinal motility disturbances which are characterised by hyperactivity of intestinal muscle, abdominal pain, diarrhoea, vomiting and nausea. During schistosomiasis, the neuropeptide somatostatin is generated within inflammatory granulomas. However, somatostatin is also an important inhibitory modulator of gastrointestinal motility. In the present study, we have investigated the potential of somatostatin to reduce schistosomiasis-induced hyperactivity of gastrointestinal smooth muscle. Organ bath experiments were performed to study the contractility of isolated smooth muscle strips of intestine from control mice and from mice that were infected with S. mansoni for 2, 4, 8 and 16 weeks. Electrical field stimulation (0.5-8 Hz) of enteric nerves induced frequency-dependent neurogenic contractions of cholinergic origin in all regions of the small intestine. Somatostatin (0.1-1 microM) concentration-dependently inhibited the contractions to enteric nerve stimulation in the small intestine from uninfected control mice and from acutely S. mansoni infected mice (2 and 4 weeks of infection). After 8 weeks of infection with S. mansoni, this inhibitory effect of somatostatin was less pronounced and after 16 weeks of infection it was completely abolished. Histology demonstrated that chronic infection of mice with S. mansoni was associated with significant alterations in the musculature of the small intestine. These alterations may be associated with physiological changes in the responsiveness to somatostatin and suggest that the somatostatin neuroregulatory circuit of enteric neurotransmission in the small intestine is disturbed during chronic schistosomiasis mansoni.     

Structure–activity relationship and improved hydrolytic stability of pyrazole derivatives that are allosteric inhibitors of West Nile Virus NS2B-NS3 proteinase

West Nile Virus (WNV) is a potentially deadly mosquito-borne flavivirus which has spread rapidly throughout the world. Currently there is no effective vaccine against flaviviral infections. We previously reported the identification of pyrazole ester derivatives as allosteric inhibitors of WNV NS2B-NS3 proteinase. These compounds degrade rapidly in pH 8 buffer with a half life of 1–2 h. We now report the design, synthesis and in vitro evaluation of pyrazole derivatives that are inhibitors of WNV NS2B-NS3 proteinase with greatly improved stability in the assay medium.     

The relationship between video game play and threat simulation dreams.

Revonsuo proposes an evolutionary theory of dreaming in which dreams allow an individual to prepare for real world threats in the safety of the virtual setting of the dream world. Based upon previous work examining the dreams of video game players, it was hypothesized that high-end gamers would experience fewer threat simulation dreams because of frequent threat resolution rehearsal during game play. Subjects were asked to report a night before dream and fill out surveys regarding their gaming history, media use, and dream experiences. Using a factor analysis, support for the main hypothesis was found. Individuals with a history of game play experienced fewer threat severity variables in their dreams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Large-scale analysis of phosphorylation site occupancy in eukaryotic proteins

Many recent high throughput technologies have enabled large-scale discoveries of new phosphorylation sites and phosphoproteins. Although they have provided a number of insights into protein phosphorylation and the related processes, an inclusive analysis on the nature of phosphorylated sites in proteins is currently lacking. We have therefore analyzed the occurrence and occupancy of phosphorylated sites (~100,281) in a large set of eukaryotic proteins (~22,995). Phosphorylation probability was found to be much higher in both the termini of protein sequences and this is much pronounced in transmembrane proteins. A large proportion (51.3%) of occupied sites had a nearby phosphorylation within a distance of 10 amino acids; however, this proportion is very high compared to the expected one (16.9%). The distribution of phosphorylated sites in proteins showed a strong deviation from the expected maximum randomness. An analysis of phosphorylation motifs indicated that just 40 motifs and a much lower number of associated kinases might account for nearly 50% of the known phosphorylations in eukaryotic proteins. Our results provide a broad picture of the phosphorylation sites in eukaryotic proteins.     

Alterations in hippocampal serotonergic and INSR function in streptozotocin induced diabetic rats exposed to stress: neuroprotective role of pyridoxine and <Emphasis Type="Italic">Aegle marmelose</Emphasis>

Diabetes and stress stimulate hippocampal 5-HT synthesis, metabolism and release. The present study was carried out to find the effects of insulin, Aegle marmelose alone and in combination with pyridoxine on the hippocampal 5-HT, 5-HT_2A receptor subtype, gene expression studies on 5-HT_2A, 5-HTT, INSR, immunohistochemical studies and elevated plus maze in streptozotocin induced diabetic rats. 5-HT content showed a significant decrease (p < 0.001) and a significant increase (p < 0.001) in 5-HIAA in hippocampus of diabetic rats compared to control. 5-HT receptor binding parameters B_max and K_d showed a significant decrease (p < 0.001) whereas 5-HT_2A receptor binding parameters B_max showed a significant decrease (p < 0.001) with a significant increase (p < 0.05) in K_d in hippocampus of diabetic rats compared to control. Gene expression studies of 5-HT_2A, 5-HTT and INSR in hippocampus showed a significant down regulation (p < 0.001) in diabetic rats compared to control. Pyridoxine treated in combination with insulin and A. marmelose to diabetic rats reversed the 5-HT content, B_max , K_d of 5-HT, 5-HT_2A and gene expression of 5-HT_2A, 5-HTT and INSR in hippocampus to near control. The gene expression of 5-HT_2A and 5-HTT were confirmed by immunohistochemical studies. Behavioural studies using elevated plus maze showed that serotonin through its transporter significantly increased (p < 0.001) anxiety-related traits in diabetic rats which were corrected by combination therapy. Our results suggest that pyridoxine treated in combination with insulin and A. marmelose has a role in the regulation of insulin synthesis and release, normalising diabetic related stress and anxiety through hippocampal serotonergic function. This has clinical significance in the management of diabetes.     

Increased cerebral matrix metalloprotease-9 activity is associated with compromised recovery in the diabetic db/db mouse following a stroke

Diabetes is a major risk factor of stroke and is associated with increased frequency of stroke and a poorer prognosis for recovery. In earlier studies we have utilized type 2 diabetic mouse models of stroke and demonstrated that diabetic db/db and ob/ob mice experience larger infarct volumes and impaired recovery associated with greater infiltration of macrophage following hypoxic-ischemic (H/I) insult than their heterozygous non-diabetic db/+ and ob/+ littermates. To obtain a better understanding of the pathogenesis of the impaired recovery, we have investigated the role of matrix metalloproteases and their endogenous inhibitors in the breakdown of the blood-brain barrier (BBB) following H/I. Diabetic db/db mice showed a significant and more rapid increase in matrix metalloprotease (MMP)-9 mRNA, protein and gelatinolytic activity compared with db/+, which resulted in an increased degradation of occludin and collagen IV and subsequently, an increased BBB permeability and greater infiltration of neutrophils into the infarct area. The expression of the MMPs, especially in the db/+ mice, is preceded by an elevated expression of their endogenous tissue inhibitors of metalloproteases (TIMPs) 1, 2, and 3, whereas in the db/db mice, a lower expression of the TIMPs is associated with greater MMP 3 and 9 expression. These results suggest that an imbalance in the MMPs/TIMPs cascade in the diabetic mouse, particularly MMP-9, results in a greater neutrophil invasion, a compromised BBB and consequently a greater insult.     

Behavioral Deficit and Decreased GABA Receptor Functional Regulation in the Hippocampus of Epileptic Rats: Effect of <Emphasis Type="Italic">Bacopa monnieri</Emphasis>

In the present study, alterations of the General GABA and GABA_A receptors in the hippocampus of pilocarpine-induced temporal lobe epileptic rats and the therapeutic application of Bacopa monnieri and its active component Bacoside-A were investigated. Bacopa monnieri (Linn.) is a herbaceous plant belonging to the family Scrophulariaceae. Hippocampus is the major region of the brain belonging to the limbic system and plays an important role in epileptogenesis, memory and learning. Scatchard analysis of [³H]GABA and [³H]bicuculline in the hippocampus of the epileptic rat showed significant decrease in B_max (P < 0.001) compared to control. Real Time PCR amplification of GABA_A receptor sub-units such as GABA_Aά1, GABA_Aά5, GABA_Aδ, and GAD were down regulated (P < 0.001) in the hippocampus of the epileptic rats compared to control. GABA_Aγ subunit was up regulated. Epileptic rats have deficit in the radial arm and Y maze performance. Bacopa monnieri and Bacoside-A treatment reverses all these changes near to control. Our results suggest that decreased GABA receptors in the hippocampus have an important role in epilepsy associated behavioral deficit, Bacopa monnieri and Bacoside-A have clinical significance in the management of epilepsy.     

Pattern of occurrence and occupancy of carbonylation sites in proteins

Proteins are targets for modification by reactive oxygen species, and carbonylation is an important irreversible modification that increases during oxidative stress. While information on protein carbonylation is accumulating, its pattern is not yet understood. We have made a meta-analysis of the available literature data (456 carbonylation sites on 208 proteins) to appreciate the nature of carbonylation sites in proteins. Of the carbonylated (Arg, Lys, Pro, and Thr - RKPT) amino acids, Lys is the most abundant, whereas Pro is the most susceptible and Thr is the least susceptible. The incidence of carbonylation is lower in the N-terminal part of the protein primary sequence. Although a significantly higher number of carbonylated sites occur in Arg-, Lys-, Pro- and Thr-rich regions of proteins, the hydropathy environment of carbonylated sites is not significantly different from potential carbonylation sites. Comparison of metal-catalyzed oxidation of two closely related proteins indicates that this type of carbonylation might not be very specific in proteins. Interestingly, carbonylated sites show a very strong tendency to cluster together in the protein primary sequence hinting at some sort of discerning mechanism. While some attributes of protein carbonylation appear to be random, further investigations are warranted to appreciate the deterministic nature of protein carbonylation sites.     

Association between Knops blood group polymorphisms and susceptibility to malaria in an endemic area of the Brazilian Amazon

Complement receptor 1 (CR1) gene polymorphisms that are associated with Knops blood group antigens may influence the binding of Plasmodium parasites to erythrocytes, thereby affecting susceptibility to malaria. The aim of this study was to evaluate the genotype and allele and haplotype frequencies of single-nucleotide polymorphisms (SNPs) of Knops blood group antigens and examine their association with susceptibility to malaria in an endemic area of Brazil. One hundred and twenty-six individuals from the Brazilian Amazon were studied. The CR1-genomic fragment was amplified by PCR and six SNPs and haplotypes were identified after DNA sequence analysis. Allele and haplotype frequencies revealed that the Kn(b) allele and H8 haplotype were possibly associated with susceptibility to Plasmodium falciparum. The odds ratios were reasonably high, suggesting a potentially important association between two Knops blood antigens (Kn(b) and KAM(+)) that confer susceptibility to P. falciparum in individuals from the Brazilian Amazon.