Effects of nitric oxide on red blood cell deformability

In addition to its known action on vascular smooth muscle, nitric oxide (NO) has been suggested to have cardiovascular effects via regulation of red blood cell (RBC) deformability. The present study was designed to further explore this possibility. Human RBCs in autologous plasma were incubated for 1 h with NO synthase (NOS) inhibitors [N(omega)-nitro-l-arginine methyl ester (l-NAME) and S-methylisothiourea], NO donors [sodium nitroprusside (SNP) and diethylenetriamine (DETA)-NONOate], an NO precursor (l-arginine), soluble guanylate cyclase inhibitors (1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one and methylene blue), and a potassium channel blocker [triethylammonium (TEA)]. After incubation, RBC deformability at various shear stresses was determined by ektacytometry. Both NOS inhibitors significantly reduced RBC deformability above a threshold concentration, whereas the NO donors increased deformability at optimal concentrations. NO donors, as well as the NO precursor l-arginine and the potassium blocker TEA, were able to reverse the effects of NOS inhibitors. Guanylate cyclase inhibition reduced RBC deformation, with both SNP and DETA-NONOate able to reverse this effect. These results thus indicate the importance of NO as a determinant of RBC mechanical behavior and suggest its regulatory role for normal RBC deformability.     

Island rat groin flaps with twisted pedicles

Clinical attempts are made to avoid rotating a flap and twisting the pedicle for fear of perfusion compromise. Torsion of an island rat groin flap pedicle is not a well-recognized experimental entity. The authors describe the results of island flap rotation with pedicle twisting in the rat groin flap model. Forty male Wistar rats were randomly divided into four groups of 10 animals each. In each group, bilateral groin flaps were elevated; one flap was sutured in place without rotation and the contralateral flap was subjected to 180, 270, 360, or 720 degrees of rotation. Blood flow within the flaps was assessed by laser Doppler flowmetry, and flap edema and necrosis were determined 10 days postoperatively. No differences were noted between control flaps and those subjected to 180 and 270 degrees of rotation. Although flaps subjected to 360 degrees of rotation demonstrated a large amount of postoperative edema and congestion of the subcutaneous tissue with some histologic changes, all flaps in this group survived. Measured flap weights at death were different from those of controls. All flaps subjected to 720 degrees of rotation underwent ischemic necrosis. Because of the differences between human skin architecture and rat skin architecture it cannot be concluded that similar results would be observed in any human skin flap. There might be three important points arising from this study of unknowingly twisted island groin flap pedicles in the rat model: (1) twisting of less than 360 degrees has no effect on flap survival; (2) twisting of 720 degrees is always associated with skin flap necrosis; (3) twisting of 360 degrees, although associated with some changes, does not cause skin flap necrosis.     

A novel and conserved pocket of human kappa-Fab fragments: design, synthesis, and verification of directed affinity ligands

Antibodies of type IgG may be divided into two classes, called lambda or kappa, depending on the type of light chain. We have identified a conserved pocket between the two domains CH1 and CL of human IgG kappa-Fab, which is not present in the lambda type. This pocket was used as a target docking site with the purpose of exploring the possibilities of designing affinity ligands that could function as such even after immobilization to gel. The idea of the design arose mainly from the results of the saturated transfer difference (STD-NMR) screening of 46 compounds identified by means of virtual docking of 60 K diverse compounds from the Available Chemicals Directory (ACD). Surface plasmon resonance (SPR) was used as an alternative method to monitor binding in solution. A total of 24 compounds belonging to a directed library were designed, synthesized, and screened in solution. They consist essentially of an amino acid condensed to a N,N'-methylated phenyl urea. STD-NMR results suggest that a small hydrophobic side chain in the condensed amino acid promotes binding, whereas a hydroxyl-group-containing side chain implies absence of STD-NMR signals. Three compounds of the directed library were immobilized and evaluated as chromatographic probes. In one case, using D-Pro as the condensed amino acid, columns packed with ligand-coupled Sepharose (Amersham Biosciences) retained two different monoclonal samples of kappa-Fab fragments with different variable regions, whereas a sample of monoclonal lambda-Fab fragments was not retained under similar chromatographic conditions.     

Bioleaching of nickel from equilibrium fluid catalytic cracking catalysts

Summary This study investigates the possibility of reusing metal-contaminated equilibrium fluid catalytic cracking (FCC) catalyst after bioleaching. Leaching with Aspergillus niger culture was found to be more effective in the mobilization of nickel from the catalyst particles compared to chemical leaching with citric acid. Bioleaching achieved 32% nickel removal whereas chemical leaching achieved only 21% nickel removal from catalyst particles. The enhanced nickel removal from the catalysts in the presence of A. niger culture was attributed to the biosorption ability of the fungal mycelium and to the higher local concentration of citric acid on the catalyst surface. It was found that 9% of solubilized nickel in the liquid medium was biosorbed to fungal biomass. After nickel leaching with A. niger culture, the hydrogen-to-methane molar ratio and coke yield, which are the measures of dehydrogenation reactions catalysed by nickel during cracking reactions, decreased significantly.     

Cytogenetic and genotoxic effects of the insecticides, imidacloprid and methamidophos

We examined the cytogenetic and genotoxic effects of the neonicotinoid insecticide imidacloprid and the organophosphate insecticide methamidophos, when administered alone or in combination. These insecticides were tested with the bone marrow chromosome aberration assay and micronucleus test in rats and by the bacterial mutation assay (Salmonella/microsome mutagenicity assay). Wistar albino rats were orally fed daily with laboratory chow treated with various concentrations of insecticides, 50 and 100 mg/kg imidacloprid, 2.5 and 5 mg/kg methamidophos, and 2.5 and 5 mg/kg imidacloprid plus methamidophos, respectively, for 90 days. Numerical and structural chromosomal aberrations were evaluated. Significant differences were detected between all the insecticide-administered groups versus the control group and between the two concentrations of the pesticide-treated groups. Both concentrations of the insecticides induced a dose-related increase in the micronucleus frequency (P < 0.05). Dose-related increases in the number of revertants were observed with the two Salmonella strains (TA98 and TA100). All tested doses of the insecticides demonstrated mutagenic activity in the presence of S9 mix. These results lead us to the conclusion that the synergistic effect of methamidophos and imidacloprid causes an increase in potential damage to non-target organisms.     

Sister chromatid exchanges in lymphocytes of nuclear medicine physicians

OBJECTIVE: The aim of this study was to assess whether occupational exposure to chronic, low doses of Iodine 131 (I-131) and Technetium 99m (Tc-99m) may lead to genotoxicity. Medical personnel occupied in nuclear medicine departments are occupationally exposed to low doses of I-131 and Tc-99m. The determination of the frequency of sister chromatid exchanges (SCEs) and of cells with a high frequency of SCEs (HFC) is considered to be a sensitive indicator for detecting genotoxic potential of mutagenic and carcinogenic agents. Therefore, we examined peripheral lymphocytes from nuclear medicine physicians for the presence of both SCE and HFC. METHODS: Sixteen exposed nuclear medicine physicians (non-smokers) were compared to 16 physicians (non-smokers) who had not been exposed to chemical or physical mutagens in their usual working environment at the same hospital. RESULTS: A statistically significant difference was found between SCE frequencies and HFC percentages measured in lymphocytes from the exposed and control groups. CONCLUSIONS: The present observation on the effect of chronic low doses of I-131 and Tc-99m indicates the possibility of genotoxic implications of this type of occupational exposure. Hence, the personnel who work in nuclear medicine departments should carefully apply the radiation protection procedures and should minimize, as low as possible, radiation exposure to avoid possible genotoxic effects.     

Activation-induced cytidine deaminase (AID) deficiency causes the autosomal recessive form of the Hyper-IgM syndrome (HIGM2)

The activation-induced cytidine deaminase (AID) gene, specifically expressed in germinal center B cells in mice, is a member of the cytidine deaminase family. We herein report mutations in the human counterpart of AID in patients with the autosomal recessive form of hyper-IgM syndrome (HIGM2). Three major abnormalities characterize AID deficiency: (1) the absence of immunoglobulin class switch recombination, (2) the lack of immunoglobulin somatic hypermutations, and (3) lymph node hyperplasia caused by the presence of giant germinal centers. The phenotype observed in HIGM2 patients (and in AID-/- mice) demonstrates the absolute requirement for AID in several crucial steps of B cell terminal differentiation necessary for efficient antibody responses.     

The role of miRNAs as a predictor of multicentricity in breast cancer

Expression profiles of miRNAs are shown to be different in various cancers to regulate expression of mRNA or to have a role in inhibition of translation, thus it shows the possible effect in progression, invasion and metastasis of breast cancer cells. The effect of breast conserving treatment in local recurrence and survival rates for the patients who have multicentric breast cancer is still controversial. In our study, we intended to evaluate the foresight of 84 miRNAs which are identified in breast cancer for having differentiated expressions. Thirty-one patients with unifocal and 26 patients with multicentric breast cancer were included in this study. These tissue samples of both malignant and normal breast tissues were kept in RNA later solution at ??80 °C. Eighty-four miRNAs were studied with miScript miRNA PCR Array Human Breast Cancer kit. Fold change, cut off value was accepted as four. In unifocal group, there were 13 upregulated and five downregulated miRNAs and in multicentric group, there were three upregulated and seven downregulated miRNAs. To reach better results for breast cancer diagnosis and treatment, it is important to enlighten tumor biology, and pay attention to target and individual therapy. Thus, miRNAs have potential role in identifying tumor characteristics in supporting diagnosis and resulting with better evaluated disease for better treatment results with individual strategies.