The role of transaminases in realizing the protective effect of L-aspartate in hypoxia]

Activation of aspartate aminotransferase and alanine aminotransferase of mitochondria introduced to the incubation medium of pyridoxal-5'-phosphate (40 microM) is approximately 2 times higher than that of the corresponding cytoplasmic forms. At hypoxia aspartate aminotransferase activity in mitochondria and postmitochondrial supernatant tends to an increase while that of alanine aminotransferase decreases (above 2 times). The protection from hypoxic damage when using L-aspartate (100 mg/kg subcutaneously 3-5 min before hypoxia) intensifies an adaptive increase of aspartate aminotransferase activity and removes a decrease of alanine aminotransferase activity. Under these conditions stimulating effect of pyridoxal-5'-phosphate on transaminases activity in vitro weakens. A simultaneous administration of vitamin-coenzyme complex (thiamine pyrophosphate, lipoate, sodium 4-phospho-pantothenate, flavin-mononucleotide, nicotinate) intensifies these metabolic shifts and protective action of L-aspartate.     

Growth-mediated variations in fatty acids of Xenorhabdus sp

The bacterium Xenorhabdus sp. is symbiotically associated with the entomopathogenic nematode Steinernema riobravis. This nematode is produced in monoxenic culture with Xenorhabdus sp. and is sold as a biological insecticide. Acceptable yields in fermentors can only be achieved in the presence of vigorous growth of the bacterium. We investigated the fatty acid composition of Xenorhabdus species when grown at 15, 20, 25 or 30 degrees C on media containing one of two primary carbon sources: glucose or lipids from the insect host, Galleria mellonella. Both temperature and primary carbon source significantly affected lipid quantity and quality in Xenorhabdus sp. Bacteria grown with insect lipids as a primary carbon source accumulated more lipids with greater proportion of longer chain fatty acids than bacteria grown with glucose as a primary carbon source. Cells grown with insect lipids at 15 degrees C had a lower lipid content than cells grown on the same media at 20, 25 or 30 degrees C. Increasing growth temperature increased saturated fatty acids and decreased unsaturated fatty acids, irrespective of carbon source. We recommend addition of complex fatty acid sources that resemble natural host lipids to growth medium for mass producing entomopathogenic nematodes. This could provide nematode quality similar to in vivo-produced nematodes.     

Carboxyl terminal region of the MukB protein in Escherichia coli is essential for DNA binding activity

Abstract The purified MukB protein of Escherichia coli has DNA binding activity and nucleotide binding activity. We have isolated a mutation, mukB1013 , causing a substitution of valine at position 1379 to leucine. This mutant MukB protein was defective for DNA binding, while the ATP binding activity remained unaffected. A truncated MukB protein that is short of 109 amino acids from the C-terminus failed to bind DNA.     

Complexes of vitamin B6. XVI. Kinetics and reaction mechanism of iron(III) complexes with pyridoxal-5′-phosphate

The stopped flow technique has been used to study the kinetics of complex formation of iron(III) with pyridoxal-5-phosphate (PLP) in the pH range 1.00–2.50, and in the temperature range 18 °C– 30 °C, at an ionic strength of. 0.50 M (NaCl). From the initial concentration dependence of PLP (T_PLP,) of the reaction rate it can be shown that two kinetic steps can be represented as: k_obs′ = m_i + m_i′_PLP where m_i and m_i′ are pH-dependent parameters. The calculated activation data are δE* = 23.2 ± 1.8 kcal mol^?1 and 10.98 ± 0.53 kcal mol^?1 for the first and second kinetic steps, respectively and δS* are ?20.50 ± 5.96 e.u. and 24.62 ± 1.81 e.u., respeetively.     

Genetic variation in vitamin D receptor gene (Fok1:rs2228570) is associated with risk of coronary artery disease

Objective: The Fok1 polymorphism (rs2228570) in vitamin D receptor gene appears to be the only polymorphism influencing size of translated protein. Investigations into its association with coronary artery disease (CAD) are sparse.

Methods: Male patients (n?=?98) with verified CAD were recruited alongside age- and sex-matched controls (n?=?55). Genotyping was performed by PCR-RFLP and plasma 25-Hydroxyvitamin D levels were assessed by HPLC-UV.

Results: The C-variant (mutant) was predominantly expressed in patients compared to controls (68.9% versus 55.5%; p?=?0.025). The observed genotypes were not associated with 25-Hydroxyvitamin D levels.

Conclusion: This study presents Fok1 polymorphism as a potential genetic marker for CAD.     

In vitro Antagonistic Interactions Between Endophytic Basidiomycetes of Oil Palm (Elaeis guineensis) and Ganoderma boninense

Ganoderma boninense is a white rot basidiomycete that causes basal stem rot disease of oil palm (Elaeis guineensis). The aims of this study were to identify endophytic basidiomycetes occurring naturally within oil palm and to assess their potential as biocontrol agents against G. boninense strain PER71 in vitro. In total, 376 isolates were recovered from samples collected from the root, stem and leaves of oil palm using Ganoderma‐selective medium. Ten of these isolates (2.7% of the total 376 isolates) were identified as basidiomycetes on the basis of clamp connections and the production of poroid basidiomes after incubation in glass jars containing PDA medium for 7–12 days. The isolates were identified using ITS rDNA sequencing as Neonothopanus nambi (five isolates), Schizophyllum commune (four isolates) and Ganoderma orbiforme (one isolate). The N. nambi isolates showed the greatest antagonistic activity against G. boninense, based on 73–85% inhibition of the radial growth measurements of G. boninense in dual culture and 76–100% inhibition of G. boninense growth in a culture filtrate assay. Possible modes of action for the antagonism shown by N. nambi against G. boninense in vitro include competition for substrate availability, space and the production of non‐volatile metabolites or antibiotics that inhibited the growth of G. boninense. Further in vivo investigations are required to determine the ability of N. nambi isolates to colonize oil palm seedlings and to protect oil palm from infection when challenged with G. boninense.     

Electrochemical detection of uric acid via uricase-immobilized graphene oxide

Measurement of the uric acid level in the body can be improved by biosensing with respect to the accuracy, sensitivity and time consumption. This study has reported the immobilization of uricase onto graphene oxide (GO) and its function for electrochemical detection of uric acid. Through chemical modification of GO using 1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS) as cross-linking reagents, the enzyme activity of the immobilized uricase was much comparable to the free enzyme with 88% of the activity retained. The modified GO-uricase (GOU) was then subjected to electrocatalytic detection of uric acid (UA) via cyclic voltammetry (CV). For that reason, a glassy carbon electrode (GCE) was modified by adhering the GO along with the immobilized uricase to facilitate the redox reaction between the enzyme and the substrate. The modified GOU/GCE outperformed a bare electrode through the electrocatalytic activity with an amplified electrical signal for the detection of UA. The electrocatalytic response showed a linear dependence on the UA concentration ranging from 0.02 to 0.49 mM with a detection limit of 3.45 μM at 3σ/m. The resulting biosensor also exhibited a high selectivity towards UA in the presence of other interference as well as good reproducibility.     

Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma

A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λ_em 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4–40 and 10–250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t‐test and the variance ratio F‐test. Copyright © 2015 John Wiley & Sons, Ltd.