Oxidative damage induced by chromium (VI) in rat erythrocytes: protective effect of selenium

Excess chromium (Cr) exposure is associated with various pathological conditions including hematological dysfunction. The generation of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. The efficacy of selenium (Se) to combat Cr-induced oxidative damage in the erythrocytes of adult rats was investigated in the current study. Female Wistar rats were randomly divided into four groups of six each: group I served as controls which received standard diet, group II received in drinking water K₂Cr₂O₇ alone (700 ppm), group III received both K₂Cr₂O₇ and Se (0.5 Na₂SeO₃ mg/kg of diet), and group IV received Se (0.5 mg/kg of diet) for 3 weeks. Rats exposed to K₂Cr₂O₇ showed an increase of malondialdehyde and protein carbonyl levels and a decrease of sulfhydryl content, glutathione, non-protein thiol, and vitamin C levels. A decrease of enzyme activities like catalase, glutathione peroxidase, and superoxide dismutase activities was also noted. Co-administration of Se with K₂Cr₂O₇ restored the parameters cited above to near-normal values. Therefore, our investigation revealed that Se was a useful element preventing K₂Cr₂O₇-induced erythrocyte damages.     

Paraoxonase-1 activity in patients with hyperemesis gravidarum

There is increasing evidence that oxidative stress may play a role in the pathophysiology of hyperemesis gravidarum. Serum paraoxonase-1 (PON-1) is a high density lipoprotein (HDL)-associated enzyme that prevents oxidative modification of low density lipoprotein. The aim of the study was to measure the serum levels of PON-1 activity in women with hyperemesis gravidarum. Thirty-four women with hyperemesis gravidarum and 31 healthy pregnant women were enrolled in the study. Serum PON-1 activity was measured spectrophotometrically. Lipid hydroperoxide (LOOH) levels were measured by iodometric assay. PON-1 activity was significantly lower and LOOH levels were significantly higher in pregnant women with hyperemesis gravidarum than in healthy pregnant women (P < 0.0001, for all). There were significant correlations between PON-1 and LOOH, triglyceride, total cholesterol, HDL, low density lipoprotein (LDL) and high sensitive C-reactive protein (HSCRP; P < 0.0001, for all). By using multiple regression analysis LDL, HDL, HSCRP and LOOH were independent determinants of serum PON-1 activity in the study. Decreased PON-1 activity might be related to increased oxidative stress and inflammation in pregnant women with hyperemesis gravidarum. Subjects with hyperemesis gravidarum might be more prone to the development of atherogenesis due to low serum PON-1 activity.     

TiO(2)-based phosphoproteomic analysis of the plasma membrane and the effects of phosphatase inhibitor treatment

Phosphorylation of plasma membrane proteins frequently initiates signal transduction pathways or attenuate plasma membrane transport processes. Because of the low abundance and hydrophobic features of many plasma membrane proteins and the low stoichiometry of protein phosphorylation, studies of the plasma membrane phosphoproteome are challenging. We present an optimized analytical strategy for plasma membrane phosphoproteomics that combines efficient plasma membrane protein preparation with TiO(2)-based phosphopeptide enrichment and high-performance mass spectrometry for phosphopeptide sequencing. We used sucrose centrifugation in combination with sodium carbonate extraction to achieve efficient and reproducible purification of low microgram levels of plasma membrane proteins from human mesenchymal stem cells (hMSCs, 10(7) cells), achieving more than 70% yield of membrane proteins. Phosphopeptide enrichment by titanium dioxide chromatography followed by capillary liquid chromatography-tandem mass spectrometry allowed us to assign 703 unique phosphorylation sites in 376 phosphoproteins. Our experiments revealed that treatment of cell cultures with three different types of protein phosphatase inhibitors produces distinct phosphopeptide populations and an increase of 10-40% of the number of detected and sequenced phosphoserine, phosphothreonine and phosphotyrosine containing peptides. In summary, our analytical strategy enables functional phosphoproteomic analysis of stem cell differentiation and cell surface biomarker discovery using very low amounts of starting material.     

Effects of Chromium Picolinate on Micronucleus Frequency and Morphology of Lymphocytes in Calves

We report the effects of chromium picolinate (CrPic) on micronucleus frequency, morphology of lymphocytes, and lipid peroxidation in calves. Twenty-four Holstein calves were selected for the study. They were kept in a farm and were fed a commercially available calf diet and alfalfa, ad libitum. The animals were divided into three groups of eight subjects each and were treated as follows: The first group was supplemented with a daily dose of 200 μg Cr as chromium picolinate; a second group received 400 μg Cr per day and a third group that served as control received no supplemental chromium. After 12-week supplementation, blood samples were collected to determine the micronucleus frequency, the apoptotic cell percentage, and the malondialdehyde (MDA) and blood chromium levels. In both supplemented groups, the cells had irregularly shaped and segmented nuclei. Supplementation also increased the percentage of apoptotic cells (p < 0.001) and serum MDA (p < 0.01) and slightly increased the chromium levels. The animals supplemented with 400 μg showed a significant increase of micronucleus frequency (p < 0.01). The results of this study suggest that supplementation with 200 and 400 μg chromium as chromium picolinate may lead to cytotoxicity. The higher level of supplementation may also have genotoxic effects. However, further studies investigating the mechanism of the action of CrPic are required.     

Maturity assessment of composted olive mill wastes using UV spectra and humification parameters

In this study, two olive mill wastes - exhausted olive cake (EOC) and paste of olive mill wastewater naturally dehydrated (POMW) - were co-composted and mixed with 25% sesame bark (SB). The humification process was evidenced by quantifying the humic substances and the generally accepted humification indices: (i) the ratio of humic acid (HA) carbon to fulvic acid (FA) carbon (CHA/CFA), (ii) the ratio of water soluble organic carbon (CW) to total organic nitrogen (Cw/Norg), (iii) and the ratio of humic acid carbon to total organic carbon CHA/Corg and by determining the absorbance ratios: E2/E4, E2/E6 and E4/E6. The results showed that the time required to reach maturity was dependant on the chemical properties of the initial raw materials used. The compost including EOC had more nitrogen and synthesised more polymerised HA, the POMW compost also had acceptable degrees of stability and maturity at the end of the process. Maturation was confirmed by a decline in Cw below 1.7, an increase in nitrogen, in HA, in CHA/CFA and an elimination of phytotoxicity. Composts produced with olive mill wastes, experimented on potato culture in the field, can be considered beneficial to soils because of their humification indexes and no toxicity.     

Protective effect of L-carnitine on testicular ischaemia-reperfusion injury in rats

Testicular torsion is a urological emergency referred to as 'acute scrotum', because inappropriate treatment can lead to male subfertility and infertility. A possible cause of testicular damage is the ischaemia-reperfusion (I/R) injury attributed to oxygen free radicals. L-carnitine, a vitamin-like antioxidant, plays a pivotal role in the maturation of spermatozoa within the reproductive tract. The aim of the present paper was to determine the protective effect of L-carnitine on testicular I/R-induced injury. Thirty-two male rats were divided into 4 groups (n = 8). Testicular torsion was created by rotating the right testis 720 degrees in a clockwise direction. Group 1: sham-operated control; group 2: ischaemia; group 3: I/R; group 4: ischaemia-L-carnitine treatment-reperfusion group. L-carnitine (500 mg kg(-1), intraperitoneally) was administered before 30 min of detorsion in Group 4. After torsion (5 h) and detorsion (5 h), bilateral orchidectomy was performed. The malondialdehyde (MDA) level was evaluated in testes. Histopathologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. Testicular MDA levels were higher in the torsion group compared to the sham-control group (p < 0.05). Detorsion (reperfusion) caused a further increase in MDA levels (p < 0.05). Pretreatment with L-carnitine prevented a further increase in MDA levels (p < 0.05). Histologically, torsion caused some separation among germinal cells in the seminiferous tubules, which became much more prominent in the I/R group but was attenuated with L-carnitine pretreatment. In conclusion, L-carnitine pretreatment may have a protective effect in experimental testicular torsion-detorsion model in rats by its well-known antioxidant potential.     

Vinpocetine ameliorates acute hepatic damage caused by administration of carbon tetrachloride in rats

Vinpocetine is a widely used drug for the treatment of cerebrovascular and memory disorders. This study aimed to investigate the effect of vinpocetine on the acute hepatic injury caused in the rat by the administration of CCl4 in vivo. Vinpocetine (2.1, 4.2, 8.4 mg/kg) or silymarin (30 mg/kg) was given once daily orally simultaneously with CCl4 and for 15 days thereafter. Liver damage was assessed by determining serum enzyme activities and hepatic histopathology. Stained sections were subjected to morphometric evaluation using computerized image analyzer. The results showed that vinpocetine administered to CCl4-treated rats decreased the elevated alanine aminotransferase (ALT) by 49.3, 58.1 and 63.6%, aspartate aminotransferase (AST) by 10.5, 22.6 and 27.2% and alkaline phosphatase (ALP) by 52.5, 59.6 and 64.9%, respectively, and in a dose-dependent manner. Meanwhile, silymarin reduced elevated ALT, AST and ALP levels by 53.1, 26.9 and 66%, respectively. Histological examination of liver specimens revealed a marked reduction in liver cell necrosis in vinpocetine and silymarin-treated rats compared with vehicle-treated CCl4-treated rats. Quantitative analysis of the area of damage showed 85.3% reduction in the area of damage after silymarin and 72.2, 78.9 and 82.6% reduction after vinpocetine treatment at 2.1, 4.2, 8.4 mg/kg, respectively. It is concluded that administration of vinpocetine in a model of CCl4-induced liver injury in rats reduced liver damage. The reduction obtained by 4.2 mg/kg of vinpocetine was similar to that obtained by 30 mg/kg silymarin. Therefore, it is suggested that vinpocetine might be a good pharmacological agent in the treatment of liver disease besides its neuroprotective effects.     

Superantigen presentation by airway smooth muscle to CD4+ T lymphocytes elicits reciprocal proasthmatic changes in airway function

Microbial products serving as superantigens (SAgs) have been implicated in triggering various T cell-mediated chronic inflammatory disorders, including severe asthma. Given earlier evidence demonstrating that airway smooth muscle (ASM) cells express MHC class II molecules, we investigated whether ASM can present SAg to resting CD4(+) T cells, and further examined whether this action reciprocally elicits proasthmatic changes in ASM responsiveness. Coincubation of CD4(+) T cells with human ASM cells pulsed with the SAg, staphylococcal enterotoxin A (SEA), elicited adherence and clustering of class II and CD3 molecules at the ASM/T cell interface, indicative of immunological synapse formation, in association with T cell activation. This ASM/T cell interaction evoked up-regulated mRNA expression and pronounced release of the Th2-type cytokine, IL-13, into the coculture medium, which was MHC class II dependent. Moreover, when administering the conditioned medium from the SEA-stimulated ASM/T cell cocultures to isolated naive rabbit ASM tissues, the latter exhibited proasthmatic-like changes in their constrictor and relaxation responsiveness that were prevented by pretreating the tissues with an anti-IL-13 neutralizing Ab. Collectively, these observations are the first to demonstrate that ASM can present SAg to CD4(+) T cells, and that this MHC class II-mediated cooperative ASM/T cell interaction elicits release of IL-13 that, in turn, evokes proasthmatic changes in ASM constrictor and relaxant responsiveness. Thus, a new immuno-regulatory role for ASM is identified that potentially contributes to the pathogenesis of nonallergic (intrinsic) asthma and, accordingly, may underlie the reported association between microbial SAg exposure, T cell activation, and severe asthma.