Readjustment of the biological exposure limit applied to blood lead levels in Brazil

We randomly selected twenty lead workers from an electric accumulator factory in the State of S?o Paulo, Brazil, whose blood lead level and urinary d-aminolevulinic acid level were below 60 mg/dL and 10 mg/L, respectively. The workers were submitted to a standard motor nerve conduction velocity study of the right radial nerves, in addition to blood lead dosage. Based on these measures, a first-order linear regression model was adjusted, where the dependent variable was conduction velocity and the independent variable was the blood lead level. Analyzing the fitted model, we inferred that the negative predictive value of the Brazilian biological exposure limit is 0.63. In order for the above biological exposure limit to have a negative predictive value of 0.99, the study suggests that it be reduced from its present value (60 mg/dL) to 32 mg/dL.     

Potential role of bcl-2 and bax mRNA and protein expression in chronic hepatitis type B and C: a clinicopathologic study.

Bcl-2 oncoprotein regulates programmed cell death by providing a survival advantage to rapidly proliferating cells, and bax protein promotes apoptosis by enchanting cell susceptibility to apoptotic stimuli. In this study, we assessed the expression of bcl-2 and bax in liver biopsies from patients with chronic hepatitis (CH) Type B (HBV) and C (HCV). The study comprised 65 liver biopsies from 65 patients with HBV (n = 37) and HCV (n = 28) and 10 normal liver biopsies as controls. The HAI score ranged from 3/18-13/18, and the fibrosis Stage, from 1-6 (7 HBV/10 HCV). Pathologic examination included the following: (1) immunohistochemical stains in paraffin sections for bcl-2 and bax protein expression, (2) Western blot analysis (bcl-2 and bax protein levels evaluation), (3) ISH (detection of bcl-2 and bax mRNA), and (4) ISH (TUNEL-ABI [apoptotic body index]). In CH cases, both bcl-2 and bax protein and mRNA were detected in portal and intralobular lymphocytes and in cholangiolar epithelial cells in interface areas and fibrous bands. Bax protein and mRNA was expressed within hepatocytes and epithelial cells of interlobular ducts in portal tracts. Bcl-2 mRNA was present in periportal hepatocytes only in cases with Stage 5-6 fibrosis. Western blot analysis showed a decreased bcl-2 and an increased bax expression toward advanced fibrotic stages. In CH cases, ABI was reverse correlated with the percentage of bcl-2 expression and was correlated directly with the percentage of bax expression (P <.001). The results of this study suggest that in cases of chronic HBV or HCV infection, bax may be involved in the hepatocyte cycle regulation during infection, whereas its expression in intraportal bile duct epithelium implies that this protein enhances susceptibility of these particular cells to apoptosis. The increased bax expression and ABI in fibrosis Stages 1-5, imply that they are responsible for hepatocytes depletion through apoptosis, during progress of liver fibrosis and fibrous tissue accumulation, until cirrhosis is established. Bcl-2 mRNA expression in periportal hepatocytes only in Stages 5 and 6 suggests that this oncogene is involved in the late stages of progressive liver fibrosis and failure and furthermore that periportal hepatocytes are resistant to apoptosis. Bcl-2 expression, in cholangioles of interface area, suggests that this oncoprotein may be involved in growth regulation of these epithelial cells. Further research is warranted to specify the exact role of apoptosis and apoptotic genes involved in liver fibrosis process in cases of chronic HBV and HCV infection. This may lead to new strategies in the management of human liver disease to prevent the progression to chronic liver failure.     

The potential role of bcl-2 mRNA and protein exression in hepatocellular carcinomas

BACKGROUND: The bcl-2 gene regulates programmed cell death by providing a survival advantage to rapidly proliferating cells. In several malignant tumors bcl-2 presence has been associated with favorable prognosis. In the liver, bcl-2 is expressed in bile ductular cells and tumors of biliary origin. This study investigates the expression of bcl-2 mRNA and protein in hepatocellular carcinomas (HCC). MATERIALS AND METHODS: The study comprised 35 primary HCC resected from 35 patients; 21 males and 14 females, aged from 43-59 years. The tumors were graded according to Edmondson criteria. In 28 cases HCC was developed on the background of cirrhotic liver. In 9 instances the patients received chemoembolization before surgery. The presence of bcl-2 mRNA was assessed on paraffin-embedded, 4 microm-thick sections, using a standard in situ hybridization method with a commercially available bcl-2 probe (Maxim Biotech, USA), while the streptavidin-biotin immunohistochemical technique was employed to detect bcl-2 protein expression using the monoclonal anti-bcl-2 antibody (DAKO, USA). The results were expressed as % of tumor-positive cells following morphometric analysis. RESULTS: The in situ hybridization study revealed bcl-2 mRNA expression in 25 out of 35 (70%) HCC. In addition, bcl-2 mRNA was detected in hyperplastic cholangioles within fibrous septae in the periphery of the tumors. Immunohistochemical staining failed to reveal any bcl-2 protein expression in tumor cells of HCC, whereas hyperplastic cholangioles of the fibrous septae, in the periphery of the tumors and intratumoral lymphocytes displayed a strong-positive cytoplasmic (perinuclear) stain. No significant correlations were recorded between bcl-2 mRNA expression and tumor histological pattern, grade, stage and the use of previous chemoembolization. CONCLUSION: In hepatocellular carcinomas, the bcl-2 gene is frequently present but its protein product is absent. This suggests a post-translational mechanism of bcl-2 protein degradation, indicating that bcl-2 does not play a substantial role in the progress of hepatocellular carcinoma.     

Endocarditis due to Salmonella enterica subsp. arizonae in a patient with sickle cell disease: a case report and review of the literature

Human cases due to Salmonella enterica subsp. arizonae are especially rare, but it may affect immunocompromised patients and infants. We present a case of endocarditis in a patient with sickle cell disease and a review of earlier cases caused by this rare human pathogen. The patient was successfully treated with ceftriaxone and ciprofloxacin. There are only few cases of salmonella endocarditis reported in the last six decades and it is the first case of Salmonella enterica subsp. arizonae endocarditis in the literature to the best of our knowledge.     

Effect of ozone and Tooth MousseTM on the efficacy of peroxide bleaching

Background:  The aim of this in vitro study was to investigate the effect of Tooth Mousse™ (TM) and ozone on the bleaching effectiveness of peroxide (P).
Methods:  Sixty enamel specimens were stained by tea infusion. P (8% carbamide peroxide solution) and the P/TM (50:50) blend were prepared freshly as required. The specimens were divided randomly into six groups: Group A – ozone followed by P; Group B – ozone concurrently with P; Group C – P alone; Group D – ozone followed by P/TM; Group E – ozone concurrently with P/TM; and Group F – P/TM alone. Ozone exposure was of 40 seconds duration. Digital photographic images were recorded at baseline and endpoint under standardized lighting and desiccation conditions. CIELAB L*a*b* values were determined.
Results:  The addition of TM to P or the application of ozone with P did not significantly affect bleaching effectiveness compared with P alone. The application of ozone prior to P significantly decreased bleaching effectiveness as indicated by the ΔL*, Δa*, ΔE and %L* values. The addition of TM to the P did enhance the aesthetic by increasing the lustre and translucency of the treated enamel.
Conclusions:  The results of this study suggest that Tooth Mousse may be applied concurrently with the bleach, and not reduce bleaching effectiveness.     

Tumor necrosis factor-alpha promotes malignant pleural effusion

Tumor necrosis factor (TNF)-alpha is present in the microenvironment of human tumors, including malignant pleural effusion (MPE). Although the cytokine is produced in the pleural cavity by both tumor and host cells, its effects on MPE formation are unknown. In these studies, we sought to determine the role of TNF-alpha in the pathogenesis of MPE and to assess the therapeutic effects of its neutralization in a preclinical model. For this, MPEs were generated in immunocompetent mice using intrapleural injection of mouse lung adenocarcinoma cells. The roles of tumor- and host-derived TNF-alpha were assessed using combined experimentation with TNF-alpha gene-deficient mice and in vivo TNF-alpha neutralization. To expand the scope of preclinical data, TNF-alpha and vascular endothelial growth factor (VEGF) expression were determined in human cancer cell lines and human MPE. In the MPE model, TNF-alpha of host and tumor origin was present. TNF-alpha neutralization significantly limited tumor dissemination, effusion formation, vascular hyperpermeability, TNF-alpha and VEGF expression, and angiogenesis, thereby improving survival. In contrast, these variables were not different between TNF-alpha gene-sufficient and TNF-alpha gene-deficient mice. In mouse cancer cells, TNF-alpha functioned via nuclear factor-kappaB- and neutral sphingomyelinase-dependent pathways to induce TNF-alpha and VEGF, respectively. These results were recapitulated in human cancer cells, and a correlation was detected between TNF-alpha and VEGF content of human MPE. We conclude that tumor-derived TNF-alpha is important in the development of MPE in mice, and provide preclinical evidence supporting the efficacy of TNF-alpha blockade against malignant pleural disease.     

Inosine monophosphate dehydrogenase and myeloid cell maturation

In previous studies of purine ribonucleotide metabolism in the human myeloid leukemia cell line HL-60, we observed that there is a down- regulation of guanine ribonucleotide biosynthesis from the central intermediate, inosine monophosphate (IMP) and a depletion of intracellular guanosine triphosphate (GTP) and guanosine diphosphate (GDP) pools that occur during the induced maturation of these cells. We also found that inhibitors of IMP dehydrogenase, the enzyme that catalyzes the first step of guanylate synthesis from IMP, are potent inducers of HL-60 maturation. Because of these observations we specifically investigated the activity of IMP dehydrogenase in HL-60 cells and in a new inducible human myeloid leukemia cell line, RDFD2- 25, both during maintenance culture and during induced maturation of the cells. Enzyme activity was examined directly in cell extracts with a radiometric assay that measures free 3H2O formed from [2-3H] IMP during the conversion of IMP to XMP. Uninduced HL-60 and RDFD2 cells in maintenance culture were found to have high levels of IMPD activity (5.2 to 5.7 pmol IMP metabolized/10(7) cells/min) compared with normal neutrophils and monocytes that had been purified from blood (less than 1.5 pmol IMP metabolized/10(7) cells/min). However, when HL-60 and RDFD2-25 cells were induced to mature with retinoic acid (10(-6) mol/L), dimethylformamide (6 X 10(-2) mol/L), or a known IMPD inhibitor, tiazofurin (10(-6) mol/L), IMPD activity in the cells fell by 51% to 80% within three to six hours. These changes in IMPD activity preceded detectable functional and antigenic maturation of the cells by at least 12 hours and were not temporally related to changes in cellular proliferation. These findings are consistent with the concept that the regulation of myeloid cell maturation may be influenced by intracellular concentrations of guanine ribonucleotides because IMP dehydrogenase activity is known to be rate limiting for the production of these nucleotides.     

L-selectin mediates neutrophil rolling in inflamed venules through sialyl LewisX-dependent and -independent recognition pathways

The glycoprotein (GP) L-selectin initiates adhesive interactions between leukocytes and endothelial cells (EC). It functions as a lymphocyte-lectin homing receptor recognizing carbohydrate determinants of the peripheral lymph node addressing on high endothelial venules. It also mediates neutrophil rolling, the earliest interaction of neutrophils with acutely inflamed venules. Neutrophil L-selectin presents sialyl-LewisX (sLe(X)) as a ligand to P- and E-selectin in vitro, and we have proposed that this is a major mechanism of L- selectin-mediated rolling in vivo. In contrast, the contribution of neutrophil L-selectin as a receptor protein recognizing one (or more) ligand(s) on inflamed EC is unclear. To address this question, an sLe(X)-negative murine pre-B cell line, L1-2, that can neither bind vascular selectins nor roll in inflamed rabbit venules, was transfected with human L-selectin cDNA. L-selectin expression in stable transfectants was sufficient to confer significant rolling in vivo. Rolling was unaffected by neuraminidase treatment but completely blocked by anti-L-selectin monoclonal antibody (MoAb) DREG-56. Thus, L- selectin can initiate leukocyte interactions with EC determinants potentially through recognition of endothelial carbohydrates. In contrast, when human neutrophils were tested, rolling was reduced, but not abolished, by MoAb DREG-56. Likewise, treatment with neuraminidase or anti-sLe(X) MoAbs decreased, but did not abrogate, neutrophil rolling, consistent with residual EC recognition via L-selectin. Combination of MoAb DREG-56 and neuraminidase resulted in almost complete loss of rolling, as did removal of glycosylated L-selectin by chymotrypsin. Together with the demonstrable rolling of L-selectin transfectants, our results support the concept of a bidirectional interaction between L-selectin bearing sLe(X) on neutrophils and activated EC in vivo. These findings also suggest that L-selectin may mediate rolling of lymphocytes that lack carbohydrate ligands for E- or P-selectin, although probably less efficiently than through bidirectional recognition.