Tinospora cordifolia modulates the seminal parameters, leakage of intracellular enzymes and seminal antioxidants in equilibrated and cryopreserved semen of Sahiwal bulls

The present study was undertaken to assess the effects of stem extract of Tinospora cordifolia (Giloy or Guduchi) in the semen extender on seminal parameters, leakage of intracellular enzymes and antioxidants in semen of Sahiwal bull. A total of 48 ejaculates from four bulls were selected for the study. Spermatozoa of 25×10⁶ were incubated in 100, 300 and 500 μg of stem extract of Guduchi as Gr II, III and IV, respectively and pre-freeze and post-thaw semen samples were analysed for seminal parameters (motility, viability, total sperm abnormality; TSA, plasma membrane integrity; PMI, and acrosomal integrity; AcI), intracellular enzymes (aspartate aminotransferase; AST and lactate dehydrogenase; LDH) and seminal antioxidants (superoxide dismutase; SOD and catalase) in comparison with an untreated control group (Gr I). The results revealed that stem extract treated semen had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in untreated control group at pre-freeze and post-thaw stages. Semen treated with 100 μg stem extract /25×10⁶ spermatozoa had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in control, 300, and 500 μg treated groups at pre-freeze and post-thaw stages. Further, these seminal parameters and antioxidants were showing decreasing trend and TSA and leakage of intra-cellular enzymes were showing increasing trend from Gr II to Gr IV at pre-freeze and post-thaw stages. Thus, 100 μg/25×10⁶ spermatozoa were optimum or suitable dose for cryopreservation of Sahiwal bull semen. The study concluded that T. cordifolia stem extract 100 μg/25×10⁶ spermatozoa in the semen extender can be effectively utilized to reduce the oxidative stress and improve the pre-freeze and post-thaw seminal parameters in Sahiwal bull. However, further studies on effects of different concentrations of stem extract on in-vitro or in-vivo fertility trials are to be conducted to assess the impact of the stem extract supplementation in the semen extender on field pregnancy outcome in bovine species.

Inhibiting Pyridoxal Kinase of Entamoeba histolytica Is Lethal for This Pathogen

Pyridoxal 5’-phosphate (PLP) functions as a cofactor for hundreds of different enzymes that are crucial to the survival of microorganisms. PLP-dependent enzymes have been extensively characterized and proposed as drug targets in Entamoeba histolytica. This pathogen is unable to synthesize vitamin B_6via de-novo pathway and relies on the uptake of vitamin B₆ vitamers from the host which are then phosphorylated by the enzyme pyridoxal kinase to produce PLP, the active form of vitamin B₆. Previous studies from our lab shows that EhPLK is essential for the survival and growth of this protozoan parasite and its active site differs significantly with respect to its human homologue making it a potential drug target. In-silico screening of EhPLK against small molecule libraries were performed and top five ranked molecules were shortlisted on the basis of docking scores. These compounds dock into the PLP binding site of the enzyme such that binding of these compounds hinders the binding of substrate. Of these five compounds, two compounds showed inhibitory activity with IC₅₀ values between 100-250 μM when tested in-vitro. The effect of these compounds proved to be extremely lethal for Entamoeba trophozoites in cultured cells as the growth was hampered by 91.5% and 89.5% when grown in the presence of these compounds over the period of 72 hours.

Characterization and functional insights into the Entamoeba histolytica pyridoxal kinase, an enzyme essential for its survival

Pyridoxal 5'-phosphate (PLP) is the active form of vitamin B₆ and a cofactor for more than 140 enzymes. This coenzyme plays a pivotal role in catalysis of various enzymatic reactions that are critical for the survival of organisms. Entamoeba histolytica depends on the uptake of pyridoxal (PL), a B₆ vitamer from the external environment which is then phosphorylated by pyridoxal kinase (EhPLK) to form PLP via the salvage pathway. E. histolytica cannot synthesise vitamin B₆de-novo, and also lacks pyridoxine 5'-phosphate oxidase, a salvage pathway enzyme required to produce PLP from pyridoxine phosphate (PNP) and pyridoxamine phosphate (PMP). Analysing the importance of PLK in E. histolytica, we have determined the high-resolution crystal structures of the dimeric pyridoxal kinase in apo, ADP-bound, and PLP-bound states. These structures provided a snapshot of the transition state and help in understanding the reaction mechanism in greater detail. The EhPLK structure significantly differed from the human homologue at its PLP binding site, and the phylogenetic study also revealed its divergence from human PLK. Further, gene regulation of EhPLK using sense and antisense RNA showed that any change in optimal level is harmful to the pathogen. Biochemical and in vivo studies unveiled EhPLK to be essential for this pathogen, while the molecular differences with human PLK structure can be exploited for the structure-guided design of EhPLK inhibitors.

Risk factors assessment of bovine tuberculosis among abattoir personnel in Gombe State, Northeastern Nigeria: A One-Health approach

Aim: Bovine tuberculosis (bTB) is an important milk-borne zoonosis that affects cattle production and poses serious threat to public health. This study aimed at assessing the risk factors as well as the level of awareness, attitude, and practices of abattoir personnel toward bTB in Gombe Township Abattoir, Gombe State. Materials and Methods: A prospective survey was conducted between October 2015 and December 2015. During the survey, a total of 112 close-ended structured questionnaires were administered to the abattoir personnel to assess their level of awareness of bTB. Results: Of these respondents, the majority were males (79%), butchers (49%) and about 40% were under the productive age brackets of 26-35 years. Majority of the respondents (85.7%) were aware of the zoonotic nature of the disease. However, only a few of the respondents (44.6%) wear personal protective equipments (PPEs) clothes while handling or in contact with carcasses during the slaughtering process. Only a few among the respondents (24.1% and 31.2%) consumed unpasteurized milk and unaware of eating of improperly cooked meat as a risk factor of bTB, respectively. About 75.7% of the respondents believed that the habit of eating and drinking inside the abattoir and during slaughtering operations has no any significant effects on their health. The results obtained show a statistically significant association between respondents' awareness of bTB and their occupational status, duration of exposure to cattle carcasses, and knowledge about the disease (p<0.05); and the odds of being aware of bTB was 10.0, 5.07, and 4.2, respectively. Conclusion: This study demonstrates the need for public health authorities to intervene in bTB prevention and control through the creation of avenues for enlightenment on the zoonotic risk associated with bTB. The risk factors associated with bTB transmission as indicated by the personnel's practice and awareness levels in Gombe township abattoir are preventable through the use of PPEs clothing.

Structural and thermodynamic characterization of metal binding in Vps29 from Entamoeba histolytica: implication in retromer function

Vps29 is the smallest subunit of retromer complex with metallo-phosphatase fold. Although the role of metal in Vps29 is in quest, its metal binding mutants has been reported to affect the localization of the retromer complex in human cells. In this study, we report the structural and thermodynamic consequences of these mutations in Vps29 from the protozoan parasite, Entamoeba histolytica (EhVps29). EhVps29 is a zinc binding protein as revealed by X-ray crystallography and isothermal titration calorimetry. The metal binding pocket of EhVps29 exhibits marked differences in its 3-dimensional architecture and metal coordination in comparison to its human homologs and other metallo-phosphatases. Alanine substitutions of the metal-coordinating residues showed significant alteration in the binding affinity of EhVps29 for zinc. We also determined the crystal structures of metal binding defective mutants (D62A and D62A/H86A) of EhVps29. Based on our results, we propose that the metal atoms or the bound water molecules in the metal binding site are important for maintaining the structural integrity of the protein. Further cellular studies in the amoebic trophozoites showed that the overexpression of wild type EhVps29 leads to reduction in intracellular cysteine protease activity suggesting its crucial role in secretion of the proteases.

Structural and functional insights into the stationary-phase survival protein SurE, an important virulence factor of Brucella abortus

The stationary-phase survival protein SurE from Brucella abortus (BaSurE) is a metal-dependent phosphatase that is essential for the survival of this bacterium in the stationary phase of its life cycle. Here, BaSurE has been biochemically characterized and its crystal structure has been determined to a resolution of 1.9 Å. BaSurE was found to be a robust enzyme, showing activity over wide ranges of temperature and pH and with various phosphoester substrates. The active biomolecule is a tetramer and each monomer was found to consist of two domains: an N-terminal domain, which forms an approximate α + β fold, and a C-terminal domain that belongs to the α/β class. The active site lies at the junction of these two domains and was identified by the presence of conserved negatively charged residues and a bound Mg(2+) ion. Comparisons of BaSurE with its homologues have revealed both common features and differences in this class of enzymes. The number and arrangement of some of the equivalent secondary structures, which are seen to differ between BaSurE and its homologues, are responsible for a difference in the size of the active-site area and the overall oligomeric state of this enzyme in other organisms. As it is absent in mammals, it has the potential to be a drug target.

Cadmium, carcinogen, co-carcinogen and anti carcinogen

As a stress agent, inducing apoptosis and blocking it, Cd can have both helpful and harmful effects. The atmosphere is a thin envelope which makes the worid a global village. Cd is the most toxic metal in air. As both the first and second messenger of the stress response, it is synergistically toxic with all other stressors, including many other carcinogens. Elimination of Pb and its replacement with added benzene in gasoline appears to have increased the toxicity of atmospheric Cd. With scientific understanding of the molecular basis of Cd's role in carcinogenesis and anti-carcinogenesis, primary cancer prevention can be practiced by reducing Cd and chemical air pollution and educating the public on smoke cessation, healthy eating habits and stress reduction. Using the existing information on Cd and its effects, determinations could be made on established cancers so that individualized treatment protocols can be developed to improve patient care.