An evaluation of impact wrench vibration emissions and test methods

In the interest of providing more effective evaluations of impact wrench vibration exposures and the development of improved methods for measuring vibration emissions produced by these tools, this study focused on three variables: acceleration measured at the tool surface, vibration exposure duration per test trial, and the amount of torque required to unseat the nuts following a test trial. For this evaluation, six experienced male impact wrench operators used three samples each of five impact wrench models (four pneumatic models and one battery-powered model) in a simulated work task. The test setup and procedures were based on those provided by an International Organization for Standardization (ISO) Technical Committee overseeing the revision of ISO 8662-7. The work task involved the seating of 10 nuts onto 10 bolts mounted on steel plates. The results indicate that acceleration magnitudes vary not only by tool type but also by individual tools within a type. Thus, evaluators are cautioned against drawing conclusions based on small numbers of tools and/or tool operators. Appropriate sample sizes are suggested. It was further noted that evaluators could draw different conclusions if tool assessments are based on ISO-weighted acceleration as opposed to unweighted acceleration. As expected, vibration exposure durations varied by tool type and by test subject; duration means varied more for study participants than they did for tool types. For the 12 pneumatic tools evaluated in this study, torque varied directly with tool handle acceleration. Therefore, in order to reduce vibration exposure, tools should be selected and adjusted so that they produce no more than the needed torque for the task at hand.

Differential dopamine receptor D4 allele association with ADHD dependent of proband season of birth

Season of birth (SOB) has been associated with attention deficit hyperactivity disorder (ADHD) in two existing studies. One further study reported an interaction between SOB and genotypes of the dopamine D4 receptor (DRD4) gene. It is important that these findings are further investigated to confirm or refute the findings. In this study, we investigated the SOB association with ADHD in four independent samples collected for molecular genetic studies of ADHD and found a small but significant increase in summer births compared to a large population control dataset. We also observed a significant association with the 7-repeat allele of the DRD4 gene variable number tandem repeat polymorphism in exon three with probands born in the winter season, with no significant differential transmission of this allele between summer and winter seasons. Preferential transmission of the 2-repeat allele to ADHD probands occurred in those who were born during the summer season, but did not surpass significance for association, even though the difference in transmission between the two seasons was nominally significant. However, following adjustment for multiple testing of alleles none of the SOB effects remained significant. We conclude that the DRD4 7-repeat allele is associated with ADHD but there is no association or interaction with SOB for increased risk for ADHD. Our findings suggest that we can refute a possible effect of SOB for ADHD.

MMP2 promoter polymorphism (C-1306T) and risk of recurrence in patients with hepatocellular carcinoma after transplantation

Genetic variants in matrix metalloproteinase (MMP) gene may influence the biological function of these enzymes and change their role in carcinogenesis and progression. The effect of MMP2 C-1306T and MMP9 C-1562T polymorphisms on genetic susceptibility has been investigated in various kinds of cancer. However, the relationship between these polymorphisms and risk of recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) has not been reported. The present study was designed to investigate the association of these two loci with the risk of HCC recurrence in 93 HCC patients treated with LT. Genotyping was performed using direct DNA sequencing. For MMP2 C-1306T variant, patients with CT heterozygous conferred a 58% reduction in recurrence risk (risk ratio: 0.419; 95% confidence interval: 0.177-0.994). The mean recurrence-free survival for CT genotype was significantly longer than that for homozygous CC patients (30.4 vs 19.3 months, p = 0.019). However, no association was found between MMP9 C-1562T polymorphisms and recurrence of HCC (p = 0.259). These findings suggest that MMP2 promoter polymorphisms may provide some predictive value for HCC recurrence after LT.

Iron chelation by clinically relevant anthracyclines: alteration in expression of iron-regulated genes and atypical changes in intracellular iron distribution and trafficking

Anthracyclines are effective anticancer agents. However, their use is limited by cardiotoxicity, an effect linked to their ability to chelate iron and to perturb iron metabolism (Mol Pharmacol 68:261-271, 2005). These effects on iron-trafficking remain poorly understood, but they are important to decipher because treatment for anthracycline cardiotoxicity uses the chelator, dexrazoxane. Incubation of cells with doxorubicin (DOX) up-regulated mRNA levels of the iron-regulated genes transferrin receptor-1 (TfR1) and N-myc downstream-regulated gene-1 (Ndrg1). This effect was mediated by iron depletion, because it was reversed by adding iron and it was prevented by saturating the anthracycline metal binding site with iron. However, DOX did not act like a typical chelator, because it did not induce cellular iron mobilization. In the presence of DOX and (59)Fe-transferrin, iron-trafficking studies demonstrated ferritin-(59)Fe accumulation and decreased cytosolic-(59)Fe incorporation. This could induce cytosolic iron deficiency and increase TfR1 and Ndrg1 mRNA. Up-regulation of TfR1 and Ndrg1 by DOX was independent of anthracycline-mediated radical generation and occurred via hypoxia-inducible factor-1alpha-independent mechanisms. Despite increased TfR1 and Ndrg1 mRNA after DOX treatment, this agent decreased TfR1 and Ndrg1 protein expression. Hence, the effects of DOX on iron metabolism were complex because of its multiple effector mechanisms.

Polyoxyethylene 40 stearate modulates multidrug resistance and enhances antitumor activity of vinblastine sulfate

Multidrug resistance (MDR) is one of the major obstacles limiting the efficacy of cancer chemotherapy. Identification of new and effective MDR reversal agents is needed. In this study, the effects of polyoxyethylene 40 stearate (PS40) on MDR were evaluated via the transport of the P-glycoprotein (P-gp) substrate vinblastine sulfate (VBL) through Caco-2 cell monolayers and rat intestine tissue. The effects of PS40 on the antitumor activity of VBL were examined through 3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay and multidrug-resistant tumor-bearing mice. Results of the transport experiments showed that PS40 reduced VBL efflux. The cytotoxicity of vinblastine to K562/ADR cells was significantly enhanced when the cells were cotreated with 100 or 150 microg/mL PS40. In vivo data revealed that average tumor volume and average tumor weight were significantly less in the VBL+PS40 group than in the VBL group. The inhibition rate for tumor growth was increased from 0.06 (VBL group) to 0.84 (VBL+PS40 group). These results suggest that PS40 may be a potentially useful adjuvant to enhance the therapeutic effects of P-gp substrates.

Formation and microbial community analysis of chloroanilines-degrading aerobic granules in the sequencing airlift bioreactor

AIMS

This paper investigates a selection-based acclimation strategy for improving the performance and stability of aerobic granules at a high chloroanilines loading.

METHODS AND RESULTS

The experiments were conducted in a sequencing airlift bioreactor (SABR) to develop aerobic granules fed with chloroanilines (ClA). The evolution of aerobic granulation was monitored using image analysis and scanning electron microscopy, and PCR-DGGE analysis of microbial community was performed. The sludge granulation was apparently developed by decreased settling time and gradual increased ClA loading to 0.8 kg m(-3) day(-1). A steady-state performance of the granular SABR was reached at last, as evidenced by biomass concentration of 6.3 g l(-1) and constant ClA removal efficiency of 99.9%. The mature granules had a mean size of 1.55 mm, minimal settling velocity of 68.4 m h(-1), specific ClA degradation rate of 0.181 g gVSS(-1) day(-1). Phylogenetic analysis of aerobic ClA-degrading granules confirmed the dominance of beta-, gamma-Proteobacteria and Flavobacteria.

CONCLUSIONS

The chosen operating strategy involving step increase in ClA loading and enhancement of major selection pressures was successful in cultivating the aerobic ClA-degrading granules.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research could be helpful for improving the stability of aerobic granules via optimizing operating conditions and developing economic feasible full-scale granular bioreactor.

Kit-like immunoreactivity in the zebrafish gastrointestinal tract reveals putative ICC

Gastrointestinal (GI) motility results from the coordinated actions of enteric neurons, interstitial cells of Cajal (ICC), and smooth muscle cells. The GI tract of the zebrafish has a cellular anatomy that is essentially similar to humans. Although enteric nerves and smooth muscle cells have been described, it is unknown if ICC are present in the zebrafish. Immunohistochemistry and PCR were used determine expression for the zebrafish Kit orthologue in the zebrafish gastrointestinal tract. Cells displaying Kit-like immunoreactivity were identified in the muscular layers of the adult zebrafish gastrointestinal tract. Two layers of Kit-positive cells were identified, one with multipolar cells located between the longitudinal and circular smooth muscle layers and one with simple bipolar cells located deep in the circular muscle layer. Primers specifically designed to amplify mRNA coding for two zebrafish kit genes, kita and kitb, and two kit ligands, kitla and kitlb, amplified the expected transcript from total RNA isolated from zebrafish GI tissues. The Sparse mutant, a kita null mutant, showed reduced contraction frequency and increased size of the GI tract indicating a functional role for kita. These data establish the presence of a cellular network with Kit-like immunoreactivity in the myenteric plexus region of the zebrafish GI tract, adjacent to enteric neurons. Expression of kita and kitb, and the ligands kitla and kitlb, were verified in the adult GI tract. The anatomical arrangement of the Kit-positive cells strongly suggests that they are ICC.

Fibrinogen controls human platelet fibronectin internalization and cell-surface retention

BACKGROUND

We recently demonstrated that platelet aggregation occurred in fibrinogen-deficient mice. In these animals, platelet fibronectin (Fn) content was increased 3-5 fold, suggesting that Fn may also be involved in platelet aggregation.

METHODS AND RESULTS

We compared platelet Fn content from a severe hypofibrinogenemic patient (with approximately 0.5% of normal fibrinogen levels) with his parents (heterozygous) and healthy donors. A significant increase in the patient's platelet Fn content was detected by immunoblot, flow cytometry, and immunoelectron microscopy (IEM). To examine the possible contribution of platelet Fn to platelet aggregation, we examined cell-surface Fn expression after thrombin treatment. Unexpectedly, IEM detected only trace amounts of Fn retained on the patient's platelet surface, and flow cytometry indicated that surface Fn was approximately 6-fold lower than that of his parents and tenfold lower than that of healthy donors. An ELISA further confirmed that the patient's platelet Fn was primarily released into the extracellular medium. To test whether retention of surface Fn was due to fibrin formation on the platelet surface, an antifibrin antibody (T2 G1) was employed. Fibrin was detected on platelets from healthy donors and from the father, but was negligible on the patient's platelets. Consistent with these data, when gel-filtered platelets of healthy donors were treated with thrombin receptor activation peptide (SFLLRN-NH(2); no conversion of fibrinogen to fibrin), little surface Fn was detected.

CONCLUSION

Fibrinogen not only competitively inhibits human platelet Fn internalization but also controls platelet-surface Fn retention via fibrin formation. The Fn-fibrin interaction is one possible mechanism to promote Fn interaction with platelets.

Substrate-induced magnetic ordering and switching of iron porphyrin molecules

To realize molecular spintronic devices, it is important to externally control the magnetization of a molecular magnet. One class of materials particularly promising as building blocks for molecular electronic devices is the paramagnetic porphyrin molecule in contact with a metallic substrate. Here, we study the structural orientation and the magnetic coupling of in-situ-sublimated Fe porphyrin molecules on ferromagnetic Ni and Co films on Cu(100). Our studies involve X-ray absorption spectroscopy and X-ray magnetic circular dichroism experiments. In a combined experimental and computational study we demonstrate that owing to an indirect, superexchange interaction between Fe atoms in the molecules and atoms in the substrate (Co or Ni) the paramagnetic molecules can be made to order ferromagnetically. The Fe magnetic moment can be rotated along directions in plane as well as out of plane by a magnetization reversal of the substrate, thereby opening up an avenue for spin-dependent molecular electronics.

Use of tumor gene expression signatures and drug-induced changes to discriminate early response in human breast cancer

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Background: To elucidate the genomics of tumor responses to different classes of chemotherapy, we analyzed breast cancer gene expression before and after in vivo treatment with adriamycin or docetaxel. Methods: Tumor biopsies were obtained before and 3 weeks after one chemotherapy cycle and tumor RNA amplified and hybridized on the Affymetrix HG-U133+2 array containing 33,000 genes. Results: Pre- and post-treatment tumors from 46 chemonaive patients with unresectable breast cancers were studied, of which 24 and 22 respectively received adriamycin and docetaxel in the first cycle, and 14 in each group had early response sensitive tumors (=25% shrinkage after 1 cycle). Comparison of our baseline gene signatures with drug-specific panels generated in vitro (Nevins, Nat Med 2006,12:1294) revealed 12 and 2 common genes (p<0.05) that predicted for adriamycin and docetaxel response respectively, with the 12 common adriamycin-response gene panel correctly predicting response in 76% of patients. Analysis of the relative change in tumor gene expression (ratio of post- and pre-treatment differential values to pre-treatment values) in our dataset revealed adriamycin to up- or down- regulate 209 transcripts (p<0.005) including genes that encode for nuclear protein, cell cycle regulation, aminopeptidases, and Ankyrin repeats, while docetaxel up- or down-regulated 469 transcripts (p<0.005) including genes that encode for extracellular matrix, transmembrane signaling, endocytosis, EGF-like calcium binding, tubulin and actin binding functions. Adriamycin and docetaxel concordantly up- or down-regulated 269 transcripts (p<0.01) that may be common response markers, including genes involved in cell cycle proliferation, mitosis, DNA damage, and carboxypeptidase activities. Adriamycin and docetaxel differentially induced 92 transcripts (p<0.01) that distinguished between the two drugs with 96% accuracy. 27 adriamycin- and 100 docetaxel-induced transcripts (p<0.005) predicted response to each drug with >90% accuracy. Conclusions: Drug-specific genomic changes can predict clinical response, and may yield insights to targets to overcome drug resistance.

No significant financial relationships to disclose.

Application of multiple parallel perfused microbioreactors and three-dimensional stem cell culture for toxicity testing

In this study, a multiple parallel perfused microbioreactor platform, TissueFlex, was developed which can be used to perform cell and tissue culture under almost uniform and precisely controlled environment in a mid-throughput and parallel manner. These microbioreactors were used to culture human bone marrow cells (hBMCs) in three-dimensional (3D) scaffolds and also in two-dimensional (2D) monolayer for comparison for upto 7 days. Several scaffolding materials were evaluated for this purpose in terms of easiness in handling, ability to support the hBMC growth, and feasibility for non-destructive optical assays. The feasibility and efficacy of using the developed 3D-hBMCs-based model tissue-constructs cultured in TissueFlex microbioreactors for drug evaluation and toxicity testing was then studied. As a demonstration case study, the cultured cells were challenged with two chemicals, trimethoprim and pyrimethamine, both known to be harmful to cellular activities, with different protocols. Cytotoxicity in terms of cell viability and growth was determined using the AlamarBlue assay. The 3D spatial variations in cell morphology and cell survival were also monitored using 3D optical imaging using non-linear multiphoton microscopy. The results show that (i) the data obtained from 3D hBMCs culture and from (2D) monolayer cultures on the effect of the tested chemicals on cell growth are significantly different, and that (ii) the perfused microbioreactor technology could provide a highly controlled and prolonged cell culture environment for testing of various drugs and chemicals. The outcome of this study demonstrated the feasibility and potentials of the using 3D stem cell based model tissues in TissueFlex microbioreactors for drug evaluation and toxicity testing of chemicals as an efficient and standardized alternative testing method.