Computational simulations assessment of mutations impact on streptokinase (SK) from a group G streptococci with enhanced activity – insights into the functional roles of structural dynamics flexibility of SK and stabilization of SK–μplasmin catalytic complex

Streptokinase (SK), a plasminogen activator (PA) that converts inactive plasminogen (Pg) to plasmin (Pm), is a protein secreted by groups A, C, and G streptococci (GAS, GCS, and GGS, respectively), with high sequence divergence and functional heterogeneity. While roles of some residual changes in altered SK functionality are shown, the underlying structural mechanisms are less known. Herein, using computational approaches, we analyzed the conformational basis for the increased activity of SK from a GGS (SKG132) isolate with four natural residual substitutions (Ile33Phe, Arg45Gln, Asn228Lys, Phe287Ile) compared to the standard GCS (SKC). Using the crystal structure of SK.Pm catalytic complex as main template SKC.μPm catalytic complex was modeled through homology modeling process and validated by several online validation servers. Subsequently, SKG132.μPm structure was constructed by altering the corresponding residual substitutions. Results of three independent MD simulations showed increased RMSF values for SKG132.μPm, indicating the enhanced structural flexibility compared to SKC.μPm, specially in 170 and 250 loops and three regions: R1 (149–161), R2 (182–215) and R3 (224–229). In parallel, the average number of Hydrogen bonds in 170 loop, R2 and R3 (especially for Asn228Lys) of SKG132 compared to that of the SKC was decreased. Accordingly, residue interaction networks (RINs) analyses indicated that Asn228Lys might induce more level of structural flexibility by generation of free Lys256, while Phe287Ile and Ile33Phe enhanced the stabilization of the SKG132.μPm catalytic complex. These results denoted the potential role of the optimal dynamic state and stabilized catalytic complex for increased PA potencies of SK as a thrombolytic drug.     

Prevalence of Neospora caninum antibodies in sheep and goats in Pakistan

The purpose of the present study was to obtain seroepidemiological information on the Neospora caninum infection status of sheep and goats in different areas of Punjab Province and Azad Kashmir (Pakistan). A cross-sectional study, with the use of a competitive ELISA, showed an overall 27.7% (35 of 128) (95% confidence interval [CI] ± 7.7%) and 8.6% (13 of 142) (95% CI ± 4.6%) seroprevalence of N. caninum antibodies in sheep and goats, respectively. The difference in seroprevalence between sheep and goat populations was statistically significant (P < 0.05). The highest prevalence (37.4% ± 13.2%) was recorded in the tailless breed of sheep.     

Production of biogas from solid organic wastes through anaerobic digestion: a review

Anaerobic digestion treatments have often been used for biological stabilization of solid wastes. These treatment processes generate biogas which can be used as a renewable energy sources. Recently, anaerobic digestion of solid wastes has attracted more interest because of current environmental problems, most especially those concerned with global warming. Thus, laboratory-scale research on this area has increased significantly. In this review paper, the summary of the most recent research activities covering production of biogas from solid wastes according to its origin via various anaerobic technologies was presented.     

The influence of continuous exposure to 50 Hz electric field on nerve regeneration in a rat peroneal nerve crush injury model

The effect of power frequency electric field (EF) on nerve regeneration was investigated on a rat peroneal nerve crush injury model. The animals were assigned to three groups: 50 Hz EF and Static EF groups were exposed at 10 kV/m. The sham group was kept in the same setting without any EF applications. EF was uninterruptedly applied for 21 days postoperatively. Repeated measures analysis of daily walking tracks during EF exposure demonstrated lower toe spread recovery (TSR) in the 50 Hz EF group. Significant difference across the groups was found only at days 7, 8, 12, 16, 17, 20, and 21 when TSR was analyzed for each measurement time. Print length recovery and peroneal function index did not differ across the groups. Walking track parameters were found to recover to their baseline values by day 28 in all groups. Day 14 but not day 21 measurements revealed smaller nerve cross-sectional area, lower total regenerating axon area, and higher mean myelin debris area in 50 Hz EF group. Both day 14 and 21 measurements revealed higher total myelin debris area, lower EDL muscle weight, and lack of significant enlargement in nerve cross-section distal to the injury, compared to the normal counterpart in 50 Hz EF group. All differences were in keeping with lower rates of Wallerian degeneration and nerve regeneration in 50 Hz EF group. When walking track, histomorphometry and muscle weight are considered individually, their differences across the groups may appear to be subtle to derive a conclusion for a 50 Hz EF effect. However, their concordance with each other in direction of effect suggests that continuous 50 Hz EF exposure has a weak effect that is detrimental mostly to the rate of early nerve regeneration in this axonotmetic injury model. Recovery of walking tracks was not different between Static EF and Sham groups. This suggests that the surface charges that may indirectly affect walking behaviors of the rats, do not account for the lower recovery of TSR in 50 Hz EF group. Differences in nerve regeneration between 50 Hz EF and Static EF groups suggests that electric induction may be required for pure EF effects even though the estimated density of induced fields is not above the endogenous background level for the 50 Hz EF exposure in this study.     

Intestinal Parasitic Infections among Inhabitants of Karaj City, Tehran Province, Iran in 2006-2008

Karaj is an area with large influx of refugee people in Iran. To increase knowledge about parasitic infections, we carried out this research during 2006-2008. We recorded the stool examination results and some of their personal characteristics. A total of 13,915 human stools were examined, and 649 (4.7%) were positive for intestinal parasites. Among them, 13 (0.09%) had worm and 636 (4.6%) had protozoan infections. Maximum infections belonged to Giardia intestinalis, and 534 (3.8%) samples had this infection. Other parasitic infections included Entamoeba coli (0.39%), Entamoeba histolytica (0.021%), Blastocystis hominis (0.08%), Trichomonas hominis (0.1%), Iodamoeba butschlii (0.06%), Chilomastix mesnili (0.007%), Endolimax nana (0.05%), Enterobius spp. eggs (0.028%), Taenia proglottids (0.028%), and Strongyloides stercoralis larvae (0.03%). The maximum numbers of referred people to laboratories were in July and the maximum percentage of infections was in August. There is a point that all 5 Strongyloides stercoralis infections were pertained to 2008. With attention to the rate of parasitic infections (4.7%), it seems that we should take additional educational information to wide spectrum of people living in this city.     

Intraflagellar transport protein 172 is essential for primary cilia formation and plays a vital role in patterning the mammalian brain

IFT172, also known as Selective Lim-domain Binding protein (SLB), is a component of the intraflagellar transport (IFT) complex. In order to evaluate the biological role of the Ift172 gene, we generated a loss-of-function mutation in the mouse. The resulting Slb mutant embryos die between E12.5 and 13.0, and exhibit severe cranio-facial malformations, failure to close the cranial neural tube, holoprosencephaly, heart edema and extensive hemorrhages. Cilia outgrowth in cells of the neuroepithelium is initiated but the axonemes are severely truncated and do not contain visible microtubules. Morphological and molecular analyses revealed a global brain-patterning defect along the dorsal-ventral (DV) and anterior-posterior (AP) axes. We demonstrate that Ift172 gene function is required for early regulation of Fgf8 at the midbrain-hindbrain boundary and maintenance of the isthmic organizer. In addition, Ift172 is required for proper function of the embryonic node, the early embryonic organizer and for formation of the head organizing center (the anterior mesendoderm, or AME). We propose a model suggesting that forebrain and mid-hindbrain growth and AP patterning depends on the early function of Ift172 at gastrulation. Our data suggest that the formation and function of the node and AME in the mouse embryo relies on an indispensable role of Ift172 in cilia morphogenesis and cilia-mediated signaling.     

Selective Deletion of PTEN in Dopamine Neurons Leads to Trophic Effects and Adaptation of Striatal Medium Spiny Projecting Neurons

The widespread distribution of the tumor suppressor PTEN in the nervous system suggests a role in a broad range of brain functions. PTEN negatively regulates the signaling pathways initiated by protein kinase B (Akt) thereby regulating signals for growth, proliferation and cell survival. Pten deletion in the mouse brain has revealed its role in controlling cell size and number. In this study, we used Cre-loxP technology to specifically inactivate Pten in dopamine (DA) neurons (Pten KO mice). The resulting mutant mice showed neuronal hypertrophy, and an increased number of dopaminergic neurons and fibers in the ventral mesencephalon. Interestingly, quantitative microdialysis studies in Pten KO mice revealed no alterations in basal DA extracellular levels or evoked DA release in the dorsal striatum, despite a significant increase in total DA tissue levels. Striatal dopamine receptor D1 (DRD1) and prodynorphin (PDyn) mRNA levels were significantly elevated in KO animals, suggesting an enhancement in neuronal activity associated with the striatonigral projection pathway, while dopamine receptor D2 (DRD2) and preproenkephalin (PPE) mRNA levels remained unchanged. In addition, PTEN inactivation protected DA neurons and significantly enhanced DA-dependent behavioral functions in KO mice after a progressive 6OHDA lesion. These results provide further evidence about the role of PTEN in the brain and suggest that manipulation of the PTEN/Akt signaling pathway during development may alter the basal state of dopaminergic neurotransmission and could provide a therapeutic strategy for the treatment of Parkinson''s disease, and other neurodegenerative disorders.     

Non-proteolytic activation of human prorenin by anti-prorenin prosegment (pf#1: 1P-15P) antiserum

Recombinant human prorenin was activated by incubation with anti-prorenin prosegment (L1PPTDTTTFKRIFLKR15P) antiserum at 4 degrees C. This activation was dependent on the concentration of the antiserum and incubation time. After the activation no molecular weight alteration of prorenin was observed by immunoblotting analysis. A peptide of L1PPTDTTTF8P as well as L1PPTDTTTFKRIFLKR15P potently interfered with the activation. Most of the activated prorenin bound to Protein A Sepharose CL 4B. The Km and Vmax values of the activated prorenin were 0.2 microM and 23.7 micrograms Ang I/ml/h, respectively, which were similar in level to those of mature renin obtained by trypsinization.