The effect of chlorpyrifos oral exposure on the histomorphometric and kidney function in Wistar rat.

BACKGROUND: Chlorpyrifos belongs to a broad-spectrum organophosphate insecticide that has high toxicity, is metabolized in the liver by the oxidation reaction, and can inhibit acetylcholinesterase activity. Acetylcholinesterase inhibition generates the reactive oxygen species and induces oxidative stress, which ultimately results in cellular damage like in the kidney. Examining blood urea nitrogen (BUN) levels, creatinine, and kidney histopathology is an appropriate indicator to assess the toxicity of chlorpyrifos to the degree of damage to cells and kidney tissue. MATERIALS AND METHODS: This research used to determine the effect of duration of exposure to chlorpyrifos and dose-response relationships is important for early detection of the effects of chlorpyrifos toxicity on health. The research study was a true experimental (completely randomized design) consisting of 30 subjects divided into 5 groups. Controlled Group (K1) given 1 mg/kg BW Tween 20 and NaCl 0, 9% until the 56th day. The chlorpyrifos exposed group (P1, P2, P3, and P4) was given chlorpyrifos 5 mg/kg BW for 7, 14, 28, and 56 days. After the treatment, BUN and creatinine levels were measured, and microscopic changes in the kidney were analyzed. The results of BUN, creatinine, and kidney histopathologic were analyzed using the analysis of variance statistical test. RESULTS: The data result showed that compared to the control group, there were significant increases of BUN and creatinine (P = 0.013 and P = 0.003). Histopathological examinations of kidney glomerulus diameter were also smaller compared to the control group (P = 0.00). All the data measurement indicates significant differences compared to the control group. CONCLUSIONS: We concluded that sub-chronic oral exposure to chlorpyrifos at low doses can damage the kidneys and cause kidney failure.

Volvulus Due to Mesenteric Cysts in Infants and Children; A Case Report.

Mesenteric cysts are defined as benign intra-abdominal tumors located in the mesentery. It was a rare disease with an incidence of 1:20000 in children. The most common location was in the small bowel mesentery. Most patients with mesenteric cysts are asymptomatic and have unspecific symptoms like dyspepsia, abdominal enlargement, and abdominal pain. The fewer others could present with an acute abdomen. We describe two cases of volvulus due to the mesenteric cyst; one case in an infant and one case in a child. There is a different clinical presentation and histopathology between infants and children. In the infant, it presented with an acute abdomen, while in the child acute abdomen was not present. We found a chylous cyst in the child while the enterogenous cyst was present in the infant. We found a volvulus due to the mesentery cyst in the infant. This comparison of mesenteric cysts between the infant and the child could help to diagnose mesenteric cysts, especially in infants.

Purification, crystallization and preliminary crystallographic analysis of a multiple cofactor-dependent DNA ligase from Sulfophobococcus zilligii.

A recombinant DNA ligase from Sulfophobococcus zilligii that shows multiple cofactor specificity (ATP, ADP and GTP) was expressed in Escherichia coli and purified under reducing conditions. Crystals were obtained by the microbatch crystallization method at 295 K in a drop containing 1 µl protein solution (10 mg ml(-1)) and an equal volume of mother liquor [0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 10 000]. A data set was collected to 2.9 Šresolution using synchrotron radiation. The crystals belonged to space group P1, with unit-cell parameters a=63.7, b=77.1, c=77.8 Å, α=83.4, ß=82.4, γ=74.6°. Assuming the presence of two molecules in the unit cell, the solvent content was estimated to be about 53.4%.

Crystallization and preliminary X-ray crystallographic analysis of Lon from Thermococcus onnurineus NA1.

Lon is an oligomeric ATP-dependent protease that degrades defective or denatured proteins as well as some folded proteins for the control of cellular protein quality and metabolism. Lon from Thermococcus onnurineus NA1 was purified and crystallized at 295 K. A 2.0 A resolution data set was collected using synchrotron radiation. The crystals belonged to space group P6(3), with unit-cell parameters a = 121.45, b = 121.45, c = 195.24 A. Assuming the presence of two monomers in the asymmetric unit, the solvent content was estimated to be about 60.7%.

Role of Phe-99 and Trp-196 of sepiapterin reductase from Chlorobium tepidum in the production of L-threo-tetrahydrobiopterin.

Sepiapterin reductase from Chlorobium tepidum (cSR) catalyzes the synthesis of a distinct tetrahydrobiopterin (BH4), L-threo-BH4, different from the mammalian enzyme product. The 3-D crystal structure of cSR has revealed that the product configuration is determined solely by the substrate binding mode within the well-conserved catalytic triads. In cSR, the sepiapterin is stacked between two aromatic side chains of Phe-99 and Trp-196 and rotated approximately 180 degrees C around the active site from the position in mouse sepiapterin reductase. To confirm their roles in substrate binding, we mutated Phe-99 and/or Trp-196 to alanine (F99A, W196A) by site-directed mutagenesis and comparatively examined substrate binding of the purified proteins by kinetics analysis and differential scanning calorimetry. These mutants had higher Km values than the wild type. Remarkably, the W196A mutation resulted in a higher Km increase compared with the F99A mutation. Consistent with the results, the melting temperature (Tm) in the presence of sepiapterin was lower in the mutant proteins and the worst was W196A. These findings indicate that the two residues are indispensable for substrate binding in cSR, and Trp-196 is more important than Phe-99 for different stereoisomer production.

Expression, purification, crystallization and preliminary X-ray analysis of sepiapterin reductase from Chlorobium tepidum.

Sepiapterin reductase from Chlorobium tepidum (CT-SR) produces L-threo-tetrahydrobiopterin, an isomer of tetrahydrobiopterin, in the last step of de novo synthesis initiating from GTP. Native CT-SR and a selenomethionine (SeMet) derivative of CT-SR have been crystallized by the hanging-drop vapour-diffusion method using PEG 400 as precipitant. CT-SR crystals belong to space group R32, with unit-cell parameters a = b = 201.142, c = 210.184 A, and contain four molecules in the asymmetric unit. Diffraction data were collected to 2.1 A resolution using synchrotron radiation. The structure of CT-SR has been determined using MAD phasing. There is one CT-SR tetramer in the asymmetric unit formed by two closely interacting CT-SR dimers. The solvent content is calculated to be about 67.2%.

Structure of Chlorobium tepidum sepiapterin reductase complex reveals the novel substrate binding mode for stereospecific production of L-threo-tetrahydrobiopterin.

Sepiapterin reductase (SR) is involved in the last step of tetrahydrobiopterin (BH(4)) biosynthesis by reducing the di-keto group of 6-pyruvoyl tetrahydropterin. Chlorobium tepidum SR (cSR) generates a distinct BH(4) product, L-threo-BH(4) (6R-(1'S,2'S)-5,6,7,8-BH(4)), whereas animal enzymes produce L-erythro-BH(4) (6R-(1'R,2'S)-5,6,7,8-BH(4)) although it has high amino acid sequence similarities to the other animal enzymes. To elucidate the structural basis for the different reaction stereospecificities, we have determined the three-dimensional structures of cSR alone and complexed with NADP and sepiapterin at 2.1 and 1.7 A resolution, respectively. The overall folding of the cSR, the binding site for the cofactor NADP(H), and the positions of active site residues were quite similar to the mouse and the human SR. However, significant differences were found in the substrate binding region of the cSR. In comparison to the mouse SR complex, the sepiapterin in the cSR is rotated about 180 degrees around the active site and bound between two aromatic side chains of Trp-196 and Phe-99 so that its pterin ring is shifted to the opposite side, but its side chain position is not changed. The swiveled sepiapterin binding results in the conversion of the side chain configuration, exposing the opposite face for hydride transfer from NADPH. The different sepiapterin binding mode within the conserved catalytic architecture presents a novel strategy of switching the reaction stereospecificities in the same protein fold.