Cytoprotective role of DL-α-Lipoic acid in cyclophosphamide induced myocardial toxicity

Cyclophosphamide (CP), a potent antitumor drug is known to cause severe cardiotoxicity. The present study is aimed at evaluating the cardioprotective role of lipoic acid in CP induced toxicity. Male albino rats of Wistar strain were divided into four groups and treated as follows: Group I served as control, Group II received a single dose of CP (200 mg/kg b.wt., i.p.), Group III received lipoic acid (25 mg/kg b.wt., orally) for 10 days, Group IV received CP immediately followed by lipoic acid for 10 days. In CP administered rats, the activities of tissue marker enzymes (creatine phosphokinase, lactate dehydrogenase, aspartate transaminase and alanine transaminase) were significantly (p<0.001) reduced, ATPases suffered loss in enzyme activity and thiols were depleted. Histopathological observations were also in agreement with the above abnormal changes. Lipoic acid effectively reverted these abnormal biochemical changes and minimized the histopathological lesions in heart. These observations highlight the protective role of lipoic acid in CP induced cardiac injury. (Mol Cell Biochem 276: 39–44, 2005)     

Genome-wide codon usage profiling of ocular infective Chlamydia trachomatis serovars and drug target identification

Chlamydia trachomatis (C.t) is a Gram-negative obligate intracellular bacteria and is a major causative of infectious blindness and sexually transmitted diseases. Among the varied serovars of this organism, A, B and C are reported as prominent ocular pathogens. Genomic studies of these strains shall aid in deciphering potential drug targets and genomic influence on pathogenesis. Hence, in this study we performed deep statistical profiling of codon usage in these serovars. The overall base composition analysis reveals that these serovars are over biased to AU than GC. Similarly, relative synonymous codon usage also showed preference towards A/U ending codons. Parity Rule 2 analysis inferred unequal distribution of AT and GC, indicative of other unknown factors acting along with mutational pressure to influence codon usage bias (CUB). Moreover, absolute quantification of CUB also revealed lower bias across these serovars. The effect of natural selection on CUB was also confirmed by neutrality plot, reinforcing natural selection under mutational pressure turned to be a pivotal role in shaping the CUB in the strains studied. Correspondence analysis (COA) clarified that, C.t C/TW-3 to show a unique trend in codon usage variation. Host influence analysis on shaping the codon usage pattern also inferred some speculative relativity. In a nutshell, our finding suggests that mutational pressure is the dominating factor in shaping CUB in the strains studied, followed by natural selection. We also propose potential drug targets based on cumulative analysis of strand bias, CUB and human non-homologue screening.     

The dose dependent effects of betulin on porcine chondrocytes

The past two decades triterpenes have attracted attention because of their pharmacological potential, especially its anti-oxidant activity. The present study was aimed to evaluate the possible protective effects of the triterpene betulin on porcine chondrocytes. For this, the cells were treated with different doses of betulin (0.02, 0.32 and 5.12 μg/mL) and without betulin. Biochemical measures of necrosis, mitochondrial activity, DNA content and sulphated glycosaminoglycans (sGAG) were reported. In addition, the gene expression of extracellular matrix molecules (ECM), proteases and soluble factors were examined. The abundance of reactive oxygen species (ROS) was also reported. Among the concentrations tried 0.32 μg/mL of betulin was found to be optimum because it effectively promoted the gene expressions of type II collagen, aggrecan and inhibited the gene expression of matrix metalloproteinase 2 (MMP-2). The chemiluminescence (CL) assay indicated that betulin treated chondrocytes had better free radical scavenging activity than the chondrocytes cultured without betulin. Alcian blue staining revealed that the chondrocytes were functionally active and able to synthesis sGAG. The free radical scavenging activity ensures betulin as protectant of chondrocytes and it further maintains the proliferation and basic activities of chondrocytes.     

Accommodating a nonconservative internal mutation by water-mediated hydrogen bonding between β-sheet strands: a comparison of human and rat type B (mitochondrial) cytochrome b5

Mammalian type B (mitochondrial) b(5) cytochromes exhibit greater amino acid sequence diversity than their type A (microsomal) counterparts, as exemplified by the type B proteins from human (hCYB5B) and rat (rCYB5B). The comparison of X-ray crystal structures of hCYB5B and rCYB5B reported herein reveals a striking difference in packing involving the five-strand β-sheet, which can be attributed to fully buried residue 21 in strand β4. The greater bulk of Leu21 in hCYB5B in comparison to that of Thr21 in rCYB5B results in a substantial displacement of the first two residues in β5, and consequent loss of two of the three hydrogen bonds between β5 and β4. Hydrogen bonding between the residues is instead mediated by two well-ordered, fully buried water molecules. In a 10 ns molecular dynamics simulation, one of the buried water molecules in the hCYB5B structure exchanged readily with solvent via intermediates having three water molecules sandwiched between β4 and β5. When the buried water molecules were removed prior to a second 10 ns simulation, β4 and β5 formed persistent hydrogen bonds identical to those in rCYB5B, but the Leu21 side chain was forced to adopt a rarely observed conformation. Despite the apparently greater ease of access of water to the interior of hCYB5B than of rCYB5B suggested by these observations, the two proteins exhibit virtually identical stability, dynamic, and redox properties. The results provide new insight into the factors stabilizing the cytochrome b(5) fold.     

Crystal Structure of Escherichia coli Enterobactin-specific Isochorismate Synthase (EntC) Bound to its Reaction Product Isochorismate: Implications for the Enzyme Mechanism and Differential Activity of Chorismate-utilizing Enzymes

EntC, one of two isochorismate synthases in Escherichia coli, is specific to the biosynthesis of the siderophore enterobactin. Here, we report the crystal structure of EntC in complex with isochorismate and Mg²⁺at 2.3 Å resolution, the first structure of a chorismate-utilizing enzyme with a non-aromatic reaction product. EntC exhibits a complex α+β fold like the other chorismate-utilizing enzymes, such as salicylate synthase and anthranilate synthase. Comparison of active site structures allowed the identification of several residues, not discussed previously, that might be important for the isochorismate activity of the EntC. Although EntC, MenF and Irp9 all convert chorismate to isochorismate, only Irp9 subsequently exhibits isochorismate pyruvate lyase activity resulting in the formation of salicylate and pyruvate as the reaction products. With a view to understanding the roles of these amino acid residues in the conversion of chorismate to isochorismate and to obtaining clues about the pyruvate lyase activity of Irp9, several mutants of EntC were generated in which the selected residues in EntC were substituted for those of Irp9: these included A303T, L304A, F327Y, I346L and F359Q mutations. Biochemical analysis of these mutants indicated that the side chain of A303 in EntC may be crucial in the orientation of the carbonyl to allow formation of a hydrogen bond with isochorismate. Some mutations, such as L304A and F359Q, give rise to a loss of catalytic activity, whereas others, such as F327Y and I346L, show that subtle changes in the otherwise closely similar active sites influence activity. We did not find a combination of these residues that conferred pyruvate lyase activity.     

Evaluation of hypoglycemic therapeutics and nutritional supplementation for type 2 diabetes mellitus management: An insight on molecular approaches

Biotechnology Letters - This review aims to summarize the current management of type 2 diabetes principles, including oral hypoglycemic agents, types of insulin administration, diet maintenance,...     

Modification of paper properties by the pretreatment of wastepaper pulp with Graphiumputredinis, Trichodermaharzianum and fusant xylanases

Graphiumputredinis, Trichodermaharzianum and fusant were used in the present study to produce extracellular xylanases, an important industrial enzyme used in pulp and paper industry produced in a minimal medium supplemented with oat spelt xylan (1%, w/v) pH 7.0 at 27+/-2 degrees C. The enzyme was purified to homogeneity by DEAE-Cellulose and Superdex 75 FPLC column, respectively. The enzyme was found to be a monomer as determined by SDS gel electrophoresis. The optimum pH and temperature for purified G. putredinis, T. harzianum and fusant xylanases were 5.0-6.0 and 50-70 degrees C, respectively. Pretreatment of paper pulp with G. putredinis, T. harzianum and fusant xylanases decreased pulp kappa number. Xylanases particularly that of fusant at 5 IU/g pulp concentration and 1.5% pulp consistency at 60 degrees C for 18 h followed by EDED process yielded good quality paper from waste paper pulp. A significant increase in pulp brightness and improvement in various pulp properties, viz. burst capacity, thickness and bulkness of the treated pulp were observed in comparison to the conventional chemical bleaching. Easy purification and high stability of these enzymes makes it amicable for industrial applications.     

Surface Temperature Distribution of a Breast With and Without Tumour

Breast cancer is a common and dreadful disease in women. Regular screening helps in its early detection. At present the most common methods of screening are by self examination and mammography. The surface temperature distribution of the breast can also provide some information on the presence of tumour. This distribution has a relation to the size and location of tumour and can be seen using thermography, where the infrared radiation emitted from the surface of the breast is recorded and a thermal pattern obtained. Thermography is a non-invasive and an inexpensive tool which could be used for early detection. In order to simulate the surface temperature distribution, a two-dimensional model of female breast with and without a carcinoma is considered. The breast is modelled with varying layer thickness close to the actual shape and numerically solved using finite element analysis. Temperature profiles are obtained for a normal breast and for a malignant one by varying the tumour size, location and the blood flow rates. The results show that the surface temperature for a malignant breast is higher than that of a normal one. In addition the size and location of the tumour do have an effect on the surface temperature distribution. It can also be seen that tumour of different sizes placed at the same location would yield the same maximum temperature depending on the blood perfusion rate.