A soluble beta-cyanoalanine synthase from the gut of the variegated grasshopper Zonocerus variegatus (L.)

Beta-cyanoalanine synthase (beta-cyano-l-alanine synthase; l-cysteine: hydrogen sulphide lyase (adding hydrogen cyanide (HCN)); EC 4. 4.1.9) was purified from the cytosolic fraction of the gut of grasshopper Zonocerus variegatus (L.) by ion-exchange chromatography on DEAE-Cellulose and gel filtration on Sephadex G-100 columns. The crude enzyme had a specific activity of 2.16nmol H2S/min/mg. A purified enzyme with a specific activity, which was seventeen times higher than that of the crude extract, was obtained. A molecular weight of about 55.23+/-1.00Kd was estimated from its elution volume on Sephadex G-100. The fraction when subjected to sodium dodecyl sulphate-polyacrylamide elel electrophoresis revealed the presence of a protein band with Mr of 23.25+/-0.25Kd. The enzyme exhibited Michaelis-Menten kinetics having Km of 0.38mM for l-cysteine and Km of 6.25mM for cyanide. The optimum temperature and pH for activity were determined to be at 30 degrees C and pH 9.0, respectively. This enzyme might be responsible for the ability to detoxify cyanide in this insect pest and hence its tolerance of the cyanogenic cassava plant. Biophysical, biochemical and kinetic properties of this enzyme, which will reveal how this ability can possibly be compromised by enzyme inhibition, may lead, in the long term, to the potential use of this enzyme as drug target for pest control.     

Contextual Risk Factors for Low Birth Weight: A Multilevel Analysis

Background

Low birth weight (LBW) remains to be a leading cause of neonatal death and a major contributor to infant and under-five mortality. Its prevalence has not declined in the last decade in sub-Saharan Africa (SSA) and Asia. Some individual level factors have been identified as risk factors for LBW but knowledge is limited on contextual risk factors for LBW especially in SSA.

Methods

Contextual risk factors for LBW in Ghana were identified by performing multivariable multilevel logistic regression analysis of 6,900 mothers dwelling in 412 communities that participated in the 2003 and 2008 Demographic and Health Surveys in Ghana.

Results

Contextual-level factors were significantly associated with LBW: Being a rural dweller increased the likelihood of having a LBW infant by 43% (OR 1.43; 95% CI 1.01–2.01; P-value <0.05) while living in poverty-concentrated communities increased the risk of having a LBW infant twofold (OR 2.16; 95% CI 1.29–3.61; P-value <0.01). In neighbourhoods with a high coverage of safe water supply the odds of having a LBW infant reduced by 28% (OR 0.74; 95% CI 0.57–0.96; P-value <0.05).

Conclusion

This study showed contextual risk factors to have independent effects on the prevalence of LBW infants. Being a rural dweller, living in a community with a high concentration of poverty and a low coverage of safe water supply were found to increase the prevalence of LBW infants. Implementing appropriate community-based intervention programmes will likely reduce the occurrence of LBW infants.     

A new flavone from Ageratum conyzoides

A new flavone has been isolated from Ageratum conyzoides and identified as 5,6,7,8,3′,4′,5′-heptamethoxyflavone on the basis of spectroscopic and degradative evidence and the assignment is confirmed by synthesis.     

Integrated assessment of the heavy metal pollution status and potential ecological risk in the Lagos Lagoon,South West,Nigeria

This study was carried out to assess the heavy metal pollution status and potential ecological risk in the Lagos lagoon, Nigeria. The concentrations of twelve heavy metals commonly associated with environmental pollution were determined in the sediments of the lagoon by Atomic Absorption Spectrophotometry (AAS) and the cold vapor method was employed for Mercury (Hg). Nonempirical risk indices and empirical Sediment Quality Guidelines (SQGs) were used to assess the ecological risk associated with heavy metal in the sediments. The nonempirical risk indices showed that Hg, Arsenic (As), and Cadmium (Cd) are the major contributors to the ecological risk associated with heavy metal pollution in the ecosystem. Comparison of heavy metal concentrations to the Screening Quick Reference Table (SQuiRT) showed that mean concentration of Cd (5.22 and 4.88 mg kg^?1 in dry and rainy seasons, respectively) exceeds the effect range low (ERL) value (1.20 mg kg^?1) in effect to biota. Industries sited around the lagoon have effluent output points in the lagoon serving as a major source of heavy metals coupled with indirect discharges from other sources. Heavy metals are nonbiodegradable, toxic and have the potential to alter ecosystem health, thus pollution sources should be effectively monitored and contained.     

Isolation and properties of cytoplasmic alpha-glycerol 3-phosphate dehydrogenase from the pectoral muscle of the fruit bat,Eidolon helvum

Cytoplasmic alpha-glycerol-3-phosphate dehydrogenase from fruit-bat-breast muscle was purified by ion-exchange and affinity chromatography. The specific activity of the purified enzyme was approximately 120 units/mg of protein. The apparent molecular weight of the native enzyme, as determined by gel filtration on Sephadex G-100 was 59,500 +/- 650 daltons; its subunit size was estimated to be 35,700 +/- 140 by SDS-polyacrylamide gel electrophoresis. The true Michaelis-Menten constants for all substrates at pH 7.5 were 3.9 +/- 0.7 mM, 0.65 +/- 0.05 mM, 0.26 +/- 0.06 mM, and 0.005 +/- 0.0004 mM for L-glycerol-3-phosphate, NAD(+), DHAP, and NADH, respectively. The true Michaelis-Menten constants at pH 10.0 were 2.30 +/- 0.21 mM and 0.20 +/- 0.01 mM for L-glycerol-3-phosphate and NAD(+), respectively. The turnover number, k(cat), of the forward reaction was 1.9 +/- 0.2 x 10(4)s(-1). The treatment of the enzyme with 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) under denaturing conditions indicated that there were a total of eight cysteine residues, while only two of these residues were reactive towards DTNB in the native enzyme. The overall results of the in vitro experiments suggest that alpha-glycerol-3-phosphate dehydrogenase of the fruit bat preferentially catalyses the reduction of dihydroxyacetone phosphate to glycerol-3-phosphate.     

Quantifying the Validity of Routine Neonatal Healthcare Data in the Greater Accra Region,Ghana

Objectives

The District Health Information Management System–2 (DHIMS–2) is the database for storing health service data in Ghana, and similar to other low and middle income countries, paper-based data collection is being used by the Ghana Health Service. As the DHIMS-2 database has not been validated before this study aimed to evaluate its validity.

Methods

Seven out of ten districts in the Greater Accra Region were randomly sampled; the district hospital and a polyclinic in each district were recruited for validation. Seven pre-specified neonatal health indicators were considered for validation: antenatal registrants, deliveries, total births, live birth, stillbirth, low birthweight, and neonatal death. Data were extracted on these health indicators from the primary data (hospital paper-registers) recorded from January to March 2012. We examined all the data captured during this period as these data have been uploaded to the DHIMS-2 database. The differences between the values of the health indicators obtained from the primary data and that of the facility and DHIMS–2 database were used to assess the accuracy of the database while its completeness was estimated by the percentage of missing data in the primary data.

Results

About 41,000 data were assessed and in almost all the districts, the error rates of the DHIMS-2 data were less than 2.1% while the percentages of missing data were below 2%. At the regional level, almost all the health indicators had an error rate below 1% while the overall error rate of the DHIMS-2 database was 0.68% (95% C I = 0.61–0.75) and the percentage of missing data was 3.1% (95% C I = 2.96–3.24).

Conclusion

This study demonstrated that the percentage of missing data in the DHIMS-2 database was negligible while its accuracy was close to the acceptable range for high quality data.     

Protective effects of Parinari curatellifolia flavonoids against acetaminophen-induced hepatic necrosis in rats

In the present study, we investigated the hepatoprotective potential of Parinari curatellifolia Planch (Chrysobalanaceae) in experimental rats in order to ascertain the validity of folkloric claims of its effectiveness in the treatment of hepatic-related disorders. Flavonoid extract of P. curatellifolia seed, PCF (10-, 20- or 30 mg/kg body weight) or silymarin (25 mg/kg), dissolved in corn oil, was administered by gavage to experimental animals once daily for 14 consecutive days before liver damage was chemically induced through the administration of acetaminophen (2 g/kg p.o.) on the 14th day. Hepatoprotection was assessed by analyzing liver homogenate and serum for markers of hepatotoxicity – alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transferase (GGT) and lactate dehydrogenase (LDH) activities as well as prothrombin time (PT). Evaluation of biochemical indices of oxidative stress – level of lipid peroxides (LPO), activities of superoxide dismutase (SOD) and catalase, along with histological assessment of hepatic tissue sections were also carried out. Results revealed that all doses of PCF significantly (P < 0.001) and dose dependently prevented acetaminophen-induced increase in serum activities of hepatic enzymes (ALT, AST, GGT, LDH) and PT. Furthermore, PCF (10- and 20 mg/kg) significantly (P < 0.001) reduced lipid peroxidation in liver tissue and restored the activities of the antioxidant enzymes SOD and catalase toward normal levels. Histopathology of the liver tissue showed that PCF mitigated the toxicant-induced hepatocellular necrosis, reduced inflammatory cell infiltration and enhanced hepatocyte regeneration. The results indicated that P. curatellifolia flavonoids demonstrated remarkable hepatoprotective activity in acute liver injury caused by acetaminophen.