Analysis of the Reduction of Ergonomic Risks through the Implementation of an Automatic Tape Packaging Machine.

Many industrial sectors still lack automation resources to optimize their production processes, aiming to make manufacturing leaner and offer better working conditions to operators. Without these improvements, workers can suffer physical and even psychological damage from the ergonomic risks of the activities performed. Thus, the aim of this paper is to present the ergonomic evaluation of packaging tapes workstation before and after the implementation of an automatic packaging machine, called Guzzetti. In the Guzzetti context, the paper shows the implementation of an electrical system based on controlling a mechanical device powered by servomotors and controlled by a PLC is necessary. For ergonomic evaluation, the paper presents the application of three methods: Suzanne Rodger, Strain Index, called Moore and Garg and REBA (Rapid Entire Body Assessment). With the results collection, was possible to obtain improvements in ergonomic risks that changed from the intermediate level to low level in all methods.

Effects of metal ions and hydrogen peroxide on the phenotype of yeast hom6Δ mutant.

UNLABELLED: HOM6 is a major gene in the aspartate pathway which leads to biosynthesis of threonine and methionine. The phenotypes of the gene deletion mutant (hom6∆) in a variety of cultural conditions have previously provided meaningful insights into the biological roles of HOM6 and its upstream intermediate metabolites. Here, we conducted a survey on a spectrum of metal ions for their effect on the aspartate pathway and broader sulphur metabolism. We show that manganese (Mn(2+) ) promoted the growth of hom6∆ under both anaerobic and aerobic conditions. Unexpectedly, 4 mmol l(-1) hydrogen peroxide (H2 O2 ), a dose normally causing temporary cell growth arrest, enhanced the growth of hom6∆ under the anaerobic condition only, while it had no effect on the wild type strain BY4743. We propose that Mn(2+) and H2 O2 promote the growth of hom6∆ by reducing the accumulation of the toxic intermediate metabolite-aspartate ß-semialdehyde, via directing the aspartate pathway to the central sugar metabolism-tricarboxylic acid cycle. SIGNIFICANCE AND IMPACT OF THE STUDY: This study focuses on the yeast strain which lacks homoserine dehydrogenase encoded by HOM6 gene in aspartate metabolism. The HOM6-deletion mutant (hom6Δ) was analysed in the context of varying environmental parameters such as metal ions and oxidants, under anaerobic and aerobic conditions. We demonstrated that both manganese and hydrogen peroxide can promote the growth of hom6Δ, with the latter exerting such effect only under anaerobic condition. The findings are relevant to the research areas of ageing and anti-fungal drug development. It highlights the importance of interactions between gene expression and environmental factors as well as culture conditions.

Susceptibility of pregnant women to toxoplasma infection--potential benefits for newborn screening.

Congenital toxoplasmosis (CT) arises as a result of new acquisition of Toxoplasma infection by a susceptible woman during pregnancy. Early detection of CT through neonatal screening programmes could optimize management and improve infant outcome. This study sought to estimate the prevalence of Toxoplasma susceptibility in pregnant women. As detection of Toxoplasma antibodies in neonatal blood reflects maternal exposure history, maternal antibody seroprevalence was determined using anonymized residual blood from newborn screening cards. A total of 20,252 cards were tested in 1 year. 4,991 (24.6%) cards tested positive for Toxoplasma antibody. Results were stratified by county. Toxoplasma antibody seroprevalence rates of 25% indicated that Toxoplasma infection is common in Ireland and that up to 75% of women remain susceptible to primary infection during pregnancy. This study aimed to a) determine the seroprevalence of Toxoplasma antibody in pregnant women, and hence b) estimate the risk for acquisition of primary toxoplasmosis in pregnancy in order to support an application to fund a pilot newborn screening programme.

Screening for Chlamydia trachomatis in asymptomatic women attending outpatient clinics in a large maternity hospital in Dublin, Ireland.

BACKGROUND: Chlamydia trachomatis can cause a sexually transmitted infection, which, untreated, may result in considerable morbidity. METHODS: A prevalence study was conducted for C trachomatis using nucleic acid amplification technology in asymptomatic women, and certain risk factors that may be used to direct future screening strategies were assessed. RESULTS: The study population comprised 945 asymptomatic women, of whom 783 were attending antenatal clinics, 91 were attending infertility clinics and 71 were attending family planning clinics. An overall C trachomatis prevalence of 3.7% (35/945) was found, with the highest prevalence of 11.2% (22/196) in Irish single women aged <25 years. Logistic regression analysis showed that single status and age <25 years were independent, statistically significant predictors of C trachomatis infection. CONCLUSION: These results support routine screening of asymptomatic women who are sexually active and aged <25 years. An opportunist active screening of all sexually active women independent of age should be additionally considered if resources permit.

Penicillin susceptibility and epidemiological typing of invasive pneumococcal isolates in the Republic of Ireland.

A national study was undertaken to investigate the incidence of invasive pneumococcal disease in the Republic of Ireland and to examine the associated isolates. In 1999, 144 S. pneumoniae isolates, all recovered from cases of invasive disease, were received from 12 microbiology laboratories. The incidence of invasive pneumococcal disease was estimated to be 6.6/100000 population. All isolates were analyzed for serotype, penicillin susceptibility, chromosomal relatedness (by using pulsed-field gel electrophoresis [PFGE]), and penicillin-binding protein (pbp) fingerprinting. Several findings of note were observed regarding the pneumococcal population in Ireland. First, isolates of 25 different serotypes were represented, with serotypes 14, 9V, 8, 5, 4, and 3 being the most common. This finding, together with the pbp fingerprinting and PFGE typing results, indicated the clonal spread of strains of these serotypes in Ireland. Second, 27 (18.7%) isolates had reduced susceptibility to penicillin, and 74% of these were serotype 9V. Of these, 80% appeared to belong to the same clone. This could suggest the spread of the international Spanish/French 9V penicillin-resistant clone into Ireland. Third, nine different pbp genotypes were identified, four of which were new. Two pbp genotypes accounted for the majority of isolates dividing them according to their penicillin susceptibility status but irrespective of serotype and PFGE type. This is strong evidence for the occurrence of horizontal transfer of pbp genes between strains, observed with both penicillin-susceptible and penicillin-nonsusceptible isolates. Fourth, there was evidence of serotype transformation since isolates, indistinguishable by pbp fingerprinting and PFGE typing, expressed different capsular types.

Design of a novel mammalian screening system for the detection of bioavailable, non-cytotoxic streptogramin antibiotics.

Screening and development of new antibiotic activities to counteract the increasing prevalence of multidrug-resistant (MDR) human pathogenic bacteria has once again become a priority in human chemotherapy. Here we describe a novel mammalian cell culture-based screening platform for the detection of streptogramin antibiotics. Quinupristin-dalfopristin (Synercid), a synthetically modified streptogramin, is presently the sole effective agent in the treatment of some MDR nosocomial infections. A Streptomyces coelicolor transcriptional regulator (Pip) has been adapted to modulate reporter gene expression (SEAP, secreted alkaline phosphatase) in Chinese hamster ovary cells (CHO) in response to streptogramin antibiotics. This CHO cell-based technology was more sensitive in detecting the production of the model streptogramin pristinamycin, from Streptomyces pristinaespiralis, than antibiogram tests using a variety of human pathogenic bacteria as indicator strains. The reporter system was able to detect pristinamycin compound produced by a single S. pristinaespiralis colony. The assay was rapid (17 hours) and could be carried out in a high-throughput 96-well plate assay format or a 24-well transwell set-up. This novel mammalian cell-based antibiotic screening concept enables detection of bioavailable and non-cytotoxic representatives of a particular class of antibiotics in a single assay and represents a promising alternative to traditional antibiogram-based screening programs.

Thioredoxin reductase two modes of catalysis have evolved.

Thioredoxin reductase (EC 1.6.4.5) is a widely distributed flavoprotein that catalyzes the NADPH-dependent reduction of thioredoxin. Thioredoxin plays several key roles in maintaining the redox environment of the cell. Like all members of the enzyme family that includes lipoamide dehydrogenase, glutathione reductase and mercuric reductase, thioredoxin reductase contains a redox active disulfide adjacent to the flavin ring. Evolution has produced two forms of thioredoxin reductase, a protein in prokaryotes, archaea and lower eukaryotes having a Mr of 35 000, and a protein in higher eukaryotes having a Mr of 55 000. Reducing equivalents are transferred from the apolar flavin binding site to the protein substrate by distinct mechanisms in the two forms of thioredoxin reductase. In the low Mr enzyme, interconversion between two conformations occurs twice in each catalytic cycle. After reduction of the disulfide by the flavin, the pyridine nucleotide domain must rotate with respect to the flavin domain in order to expose the nascent dithiol for reaction with thioredoxin; this motion repositions the pyridine ring adjacent to the flavin ring. In the high Mr enzyme, a third redox active group shuttles the reducing equivalent from the apolar active site to the protein surface. This group is a second redox active disulfide in thioredoxin reductase from Plasmodium falciparum and a selenenylsulfide in the mammalian enzyme. P. falciparum is the major causative agent of malaria and it is hoped that the chemical difference between the two high Mr forms may be exploited for drug design.

Twists in catalysis: alternating conformations of Escherichia coli thioredoxin reductase.

In thioredoxin reductase (TrxR) from Escherichia coli, cycles of reduction and reoxidation of the flavin adenine dinucleotide (FAD) cofactor depend on rate-limiting rearrangements of the FAD and NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) domains. We describe the structure of the flavin-reducing conformation of E. coli TrxR at a resolution of 3.0 angstroms. The orientation of the two domains permits reduction of FAD by NADPH and oxidation of the enzyme dithiol by the protein substrate, thioredoxin. The alternate conformation, described by Kuriyan and co-workers, permits internal transfer of reducing equivalents from reduced FAD to the active-site disulfide. Comparison of these structures demonstrates that switching between the two conformations involves a "ball-and-socket" motion in which the pyridine nucleotide-binding domain rotates by 67 degrees.

Crystal structure of reduced thioredoxin reductase from Escherichia coli: structural flexibility in the isoalloxazine ring of the flavin adenine dinucleotide cofactor.

Catalysis by thioredoxin reductase (TrxR) from Escherichia coli requires alternation between two domain arrangements. One of these conformations has been observed by X-ray crystallography (Waksman G, Krishna TSR, Williams CH Jr, Kuriyan J, 1994, J Mol Biol 236:800-816). This form of TrxR, denoted FO, permits the reaction of enzyme-bound reduced FAD with a redox-active disulfide on TrxR. As part of an investigation of conformational changes and intermediates in catalysis by TrxR, an X-ray structure of the FO form of TrxR with both the FAD and active site disulfide reduced has been determined. Reduction after crystallization resulted in significant local conformation changes. The isoalloxazine ring of the FAD cofactor, which is essentially planar in the oxidized enzyme, assumes a 34 degree "butterfly" bend about the N(5)-N(10) axis in reduced TrxR. Theoretical calculations reported by others predict ring bending of 15-28 degrees for reduced isoalloxazines protonated at N(1). The large bending in reduced TrxR is attributed in part to steric interactions between the isoalloxazine ring and the sulfur of Cys138, formed by reduction of the active site disulfide, and is accompanied by changes in the positions and interactions of several of the ribityl side-chain atoms of FAD. The bending angle in reduced TrxR is larger than that for any flavoprotein in the Protein Data Bank. Distributions of bending angles in published oxidized and reduced flavoenzyme structures are different from those found in studies of free flavins, indicating that the protein environment has a significant effect on bending.

Reductive half-reaction of thioredoxin reductase from Escherichia coli.

Thioredoxin reductase is a homodimeric flavoenzyme containing a flavin adenine dinucleotide (FAD) and a redox-active disulfide in each subunit. Structural work on the enzyme from Escherichia coli suggests that thioredoxin reductase exists in two conformations, both of which are necessary for catalysis [Waksman, G., Krishna, T. S. R., Williams, C. H., Jr., & Kuriyan, J. (1994) J. Mol. Biol. 236, 800-816]. These factors make it likely that the mechanism of this enzyme is complex. The rapid reaction of enzyme with nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) (the reductive half-reaction), proceeds in three phases. The first phase represents the formation of an NADPH-FAD charge transfer complex. The second phase involves FAD reduction, with loss of the NADPH-FAD charge transfer band. The third phase shows a slower decrease in absorbance at 456 nm and the formation of a reduced flavin-NADP+ charge transfer band. These and other results indicate that NADP+ and NADPH compete for the single binding site on oxidized and fully reduced enzyme and that NADP+ release does not limit the third phase of reduction. Experiments that include examination of the reductive half-reactions of active-site mutants, having the active-site disulfide removed by mutating one or both of the active-site cysteines, indicate that the third phase does not represent reduction by a second equivalent of NADPH. Comparison of the rate constants and temperature dependence of the reductive half-reaction with those of turnover show that the reductive half-reaction is not solely rate-limiting in catalysis. The results suggest that wild type and each altered enzyme exists in a unique equilibrium of conformers. It is proposed that the third phase of the reductive half-reaction represents a flavin reduction event largely limited by the conformational change proposed in the structural work.

Processing of semen in an antibiotic-rich culture medium to minimize microbial presence during in vitro fertilization.

OBJECTIVE: To identify and determine the prevalence of microorganisms in preprocessed and postprocessed semen in an IVF-ET program. DESIGN: Prospective study. SETTING: University Teaching Hospital. PATIENT(S): Seventy-four men undergoing preprogram evaluation, each producing two semen samples. INTERVENTION(S): Semen processing with a wash and swim-up technique in a penicillin- and streptomycin-rich medium. MAIN OUTCOME MEASURE(S): The identity and prevalence of seminal microorganisms before and after processing. RESULT(S): Sixty-three percent of individual unprocessed semen samples grew microorganisms, the majority of which were nonpathogenic. Thirty-three men (44.6%) had microbes identified in repeat samples, four had identical organisms each time. Twenty (27%) had positive cultures in one sample, negative in the other. Twenty-one (28.4%) had consistently sterile semen. After seminal processing, the recovery rate for microbes was 5%. Microbial presence after processing did not correlate with either the sperm swim-up concentration or the initial microbial concentration. CONCLUSION(S): Bacteriospermia is common. The microorganisms found rarely are replicated and most likely represent contamination. Wash and swim-up semen preparation in an antibiotic rich culture medium effectively eliminates 95% of organisms.

Community study of toxoplasma antibodies in urban and rural schoolchildren aged 4 to 18 years.

To estimate the prevalence of toxoplasma antibodies in schoolchildren and their association with clinical and environmental data, antibody titres were measured in 1276 children aged 4 to 18 years attending primary and secondary schools. Environmental and clinical data were obtained by questionnaire. Altogether 12.8% (163/1276) of children had antibodies to Toxoplasma gondii with no difference between the sexes. Seroprevalence was higher in country children (16.6% (50/302)) than town children (10.2% (75/737)). The proportion testing positive increased with age in both town and country children. No association with cat ownership was found. Toxoplasma seropositivity was associated with a positive toxocara titre, having had a bitch whelp in the past two years, and having an unwormed dog at home. Lack of energy or tiredness in the last 12 months were the only clinical features associated with a positive titre.

Microbial contamination in an in vitro fertilization-embryo transfer system.

OBJECTIVE: To determine sources and transmission of microorganisms in IVF-ET and efficacy of in-place controlling systems. DESIGN: Prospective study. SETTING: In Vitro Fertilization-Embryo Transfer Unit at a university teaching hospital. PATIENTS: Twenty-eight couples undergoing 30 completed IVF-ET cycles. INTERVENTIONS: Gamete and embryo processing in a penicillin and streptomycin-rich medium. MAIN OUTCOME MEASURES: Presence of microorganisms at various stages of IVF-ET. Fertilization, cleavage, and pregnancy rates. RESULTS: In 50% of cycles no microorganisms were isolated and in the other 50% microbes were cultured from various loci. Cultures of four preprocessed semen samples were positive and corresponding postprocessed samples negative. Microbes were detected in 27% of needle washes after oocyte collection; in 40% and 32% of follicular fluids from left and right ovaries, respectively; and in two culture media from egg-sperm incubations at 20 hours after insemination. No microorganisms were grown from media from zygote incubations. Fertilization, cleavage, and pregnancy rates were independent of microbial presence. CONCLUSION: Seminal fluid and transvaginally collected oocytes are potential sources of microbial contamination of the IVF-ET culture system. A penicillin- and streptomycin-rich culture medium is effective in removing contaminating microbes. End point measures are not affected by commensal contamination.

Enzyme-monitored turnover of Escherichia coli thioredoxin reductase: insights for catalysis.

Thioredoxin reductase from Escherichia coli is a member of the pyridine nucleotide-disulfide oxidoreductase family, and contains one FAD and one redox-active disulfide per subunit. It is known that two other well-studied members of this family, lipoamide dehydrogenase and glutathione reductase, cycle between the two electron-reduced and fully oxidized forms in catalysis. Enzyme-monitored turnover shows that the spectrum of thioredoxin reductase during turnover represents fully reduced flavin with NADP(H) bound. Whether the pyridine nucleotide bound is NADPH or NADP+ is dependent on the concentration of each species, i.e., how far turnover has progressed. It is also shown that the midpoint potentials of this enzyme are increased through the differential binding of NADP+ to the oxidized and reduced form of the enzyme. When combined with other kinetic and oxidation/reduction studies of this enzyme, these results indicate that thioredoxin reductase cycles between the four-electron-reduced and two-electron-reduced forms in catalysis, and that it does so with pyridine nucleotide bound. These results clarify the mechanism of thioredoxin reductase in relation to the known structure the enzyme, and provide support for earlier work in which we proposed that this enzyme utilizes a ternary complex mechanism in catalysis.

Menstrual cycle symptom reporting in three British ethnic groups.

Three different British ethnic groups were targeted to assess the influence of learned or culturally prescribed symptom reporting behaviour across different phases of the menstrual cycle. Forty-eight Afro-Caribbean, 73 Caucasian and 32 Oriental subjects completed a Positive/Negative Affectivity scale, a Retrospective assessment of premenstrual symptoms and daily symptom reports for 35 days. The results showed a significantly elevated level of symptomatology premenstrually and menstrually in the Caucasian group compared to both others. Analysis of subscales suggested elevated symptom reporting occurred for the psychological mood, body symptoms and pain, but not for the mental performance and social behaviour subscales. Intermenstrual reports of symptoms and Negative Affectivity did not differ between groups. A response bias or underlying trait is therefore unlikely to account for the selective reporting observed. It is suggested that the question of learning variables playing an important role in the reporting of symptoms at different phases of the menstrual cycle may be reopened.

Menstrual cycle symptom reporting in three British Ethnic groups

Three different British ethnic groups were targeted to assess the influence of learned or culturally prescribed symptom reporting behaviour across different phases of the menstrual cycle. Forty-eight Afro-Caribbean, 73 Caucasian and 32 Oriental subjects completed a positive/negative affectivity scale, a retrospective assessment of premenstrual symptoms and daily symptom reports for 35 days. The results showed a significantly elevated level of symptomatology premenstrually and menstually in the Caucasian groups compared to both others. Analysis of subscales suggested elevated symptom reporting occurred for the psychological mood, body symptoms and pain, but not for the mental performance and social behaviour subscales. Intermenstrual reports of symptoms and negative affectivity did not differ between groups. A response bias or underlying trait is therefore unlikely to account for the selective reporting observed. It is suggested that the question of learning variables playing an important role in the reporting of symptoms at different phases of the menstrual cycle may be reopened (AU)

Effect of pyridine nucleotide on the oxidative half-reaction of Escherichia coli thioredoxin reductase.

The kinetics of the oxidative half-reaction between reduced thioredoxin reductase and oxidized thioredoxin measured in the presence and absence of pyridine nucleotide show a significant difference in the rates of the main phase of oxidation. When 1 equiv of NADPH is used to partially reduce the enzyme at pH 7.0 or 7.6, the observed rate of the catalytically competent phase of oxidation is essentially equal to kcat at that pH. This is about 50% of the rate of oxidation observed with enzyme fully reduced or partially reduced by the xanthine/xanthine oxidase system or by dithionite. Through the use of the nonreducible analog 3-aminopyridine adenine dinucleotide phosphate we have shown that this decrease in observed rate of oxidation is linked to the concentration of pyridine nucleotide present. This suggests that the complexation of pyridine nucleotides with reduced thioredoxin reductase is able to effect a change in the rate-limiting steps of the oxidation of the enzyme by thioredoxin. This is the case even when substoichiometric quantities of 3-aminopyridine adenine dinucleotide phosphate are present, which predicts that the binding to reduced enzyme is very tight. It is clear that the presence of 1 equiv of NADP+ is sufficient to cause the observed rate for the catalytically competent phase of oxidation to decrease to kcat. Thus, there is compelling evidence for a ternary complex mechanism for thioredoxin reductase.

Isolation of a crotoxin-like protein from the venom of a South American rattlesnake (Crotalus durissus collilineatus).

1. A crotoxin-like protein was isolated from the venom of a South American rattlesnake Crotalus durissus collilineatus. 2. Many of its properties are similar to those of crotoxin, including its non-covalent heterodimeric structure, electrophoretic mobility on SDS-PAGE, isoelectric focusing properties, toxicity in mice, immunological reactivity, multiple isoforms, phospholipase activity, peptide map, and instability on an anion-exchange column. 3. Results indicate that "collilineatus toxin" is strongly homologous with crotoxin, found in the venom of Crotalus durissus terrificus, and all other characterized rattlesnake neurotoxins.

Effects of subunit cross-linking on the properties of crotoxin.

Crotoxin was cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. Cross-linked crotoxin had the expected amino-terminal amino acids, amino acid composition, behavior on SDS-PAGE and an 80% reduction of reactable lysine residues. It was also non-toxic, had reduced immunological cross-reactivity toward both poly- and monoclonal antibodies raised to the basic subunit of crotoxin and had lost greater than 95% of its phospholipase activity. Loss of toxicity is due to either subunit cross-linking or the modification of essential residues.