A new method for evaluating industrial heat exposure and maximum permissible work load

The paper presents a new method for the evaluation of the physiological limit of heat exposure dependent on the metabolic rate, environmental temperature, humidity and air motion. The method consists of the determination of the conditions of work and exposure that would cause a given rate of sweating which might be considered as the physiologically permissible limit for prolonged exposure, e.g. 1100 g/hr. The expected sweat rate under given conditions of work and thermal environment is given by the formula: S=E (1/f), where S is the expected sweat rate, E is the required evaporative cooling which is equal to the overall heat load, and f is the cooling efficiency of sweating. Formulas and nomograms are presented, which enable quantitative determination of the various components of the formula. Examination of the correlation between the suggested method, and experimental results from several physiological investigations in different countries showed good agreement and linear relationship between the measured and the computed values.

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Zusammenfassung Eine neue Methode zur Bewertung der physiologischen Grenzen der Hitzebelastung unter Berücksichtigung der Stoffwechselrate, der Umgebungstemperatur, Feuchtigkeit und Luftbewegung, wird beschrieben. Die Methode beruht auf der Bestimmung der jenigen Bedingungen bei der Arbeit und Exponierung, die zu einer gegebenen Schweissrate führen und die angesehen werden können als die physiologisch zulÄssige Grenze bei verlÄngerter Exponierung, z.B. 1100 g/hr. Die erwartete Schweissrate bei gegebenen Bedingungen (Arbeit und WÄrme) wird ausgedrückt in der Gleichung: S=E (1/f), darin ist S die erwartete Schweissrate, E die erforderliche VerdunstungskÄlte, die gleich ist mit der gesamten Hitzebelastung und f ist die Abkühlungsleistung beim Schwitzen. Formeln und Nomogramme für die quantitative Bestimmung der verschiedenen Komponenten der Gleichung werden angegeben. Eine Prüfung der Korrelation zwischen der vorgeschlagenen Methode und Ergebnissen von mehreren physiologischen Untersuchungen in verschiedenen LÄndern zeigte eine gute übereinstimmung und lineare Beziehung zwischen den gemessenen und berechneten Werten.

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Resume Ce mémoire présente une nouvelle méthode qui permet d'évaluer la limite physiologique de l'exposition à la chaleur, limite dépendant du métabolisme d'une part, de la température, de l'humidité et du vent d'autre part. Cette méthode consiste à déterminer dans quelles conditions de travail et de chaleur une certaine quantité de sueur est sécrétée. Cette quantité (par exemple 1100 g/hr)peut Être considérée comme la limite admissible, du point de vue physiologique, pour une exposition prolongée. La quantité de sueur probable peut alors Être calculée dans des conditions de travail et d'ambiance thermique données au moyen de la formule: S=E (1/f) où S est la quantité de sueur recherchée, E le refroidissement par évaporation indispensable (il est égal à la charge calorifique totale) et f l'efficacité de refroidissement de la sueur. On donne en outre des équations et des abaques permettant de déterminer quantitativement les divers éléments de cette formule. La corrélation est bonne entre la dite méthode de calcul et les résultats numériques provenant d'essais physiologiques effectués dans divers pays. Les valeurs mesurées et calculées forment entre eux une fonction linéaire.

     

Mitotic cycle of a HeLa cell culture exposed to the maximum permissible concentrations of trace elements

It is shown that administration of certain trace elements in maximum allowable concentrations induces changes in metabolism and functionation of cells in the culture. Zinc, nickel, cobalt, cadmium and fluorine are stated to inhibit mitotic activity of HeLa cells by the end of 24 hours of their action. Parallel with this they promote a decrease in H3-thymidine incorporation into DNA. Besides these substances delay various stages of the mitotic cycle for cells.     

Determination of the biochemical oxygen demand in nutrient media using microbial flow-through electrodes

Biochemical oxygen demand (BOD) in some culture media was determined by means of flow-through microbial electrodes, based on Hansenula anomala, Escherichia coli K-12, and activated sludge obtained from the All-Union Scientific-Research Institute of Applied Enzymology (Vilnius). The sensitivity of the electrodes was 112.1, 65.5 and 32.8% O2, respectively, in the presence of 1 mM glucose as substrate. A maximum sensitivity of the electrodes, based on E. coli and activated sludge, was observed on pyruvate oxidation--120 and 82.3% O2 in the presence of 1 mM pyruvate. The yeast electrode exhibited a minimum sensitivity for sucrose--9.3% O2/mM. The time of the electrode response varies from 8 to 35 min, depending on the substrate used. BOD depends on pH of the solution. The microbial electrodes retained the initial sensitivity for 33--38 days. The were used for estimation of BOD in the Rider's and Shopfer's media.     

Determination of the Escherichia coli S-nitrosoglutathione response network using integrated biochemical and systems analysis

During infection or denitrification, bacteria encounter reactive nitrogen species. Although the molecular targets of and defensive response against nitric oxide (NO) in Escherichia coli are well studied, the response elements specific to S-nitrosothiols are less clear. Previously, we employed an integrated systems biology approach to unravel the E. coli NO-response network. Here we use a similar approach to confirm that S-nitrosoglutathione (GSNO) primarily impacts the metabolic and regulatory programs of E. coli in minimal medium by reaction with homocysteine and cysteine and subsequent disruption of the methionine biosynthesis pathway. Targeting of homocysteine and cysteine results in altered regulatory activity of MetJ, MetR, and CysB, activation of the stringent response and growth inhibition. Deletion of metJ or supplementation with methionine strongly attenuated the effect of GSNO on growth and gene expression. Furthermore, GSNO inhibited the ArcAB two-component system. Consistent with the underlying nitrosative and thiol-oxidative chemistry, growth inhibition and the majority of the regulatory perturbations were dependent upon GSNO internalization by the Dpp dipeptide transporter. Contrastingly, perturbation of NsrR appeared to be a result of the submicromolar levels of NO released from GSNO and did not require GSNO internalization.     

Determination of D- and L-alanine concentrations using a pyruvic acid sensor

The concentrations of D- and L-alanine in bivalves are useful as indicators of environmental pollution. Amino acid oxidase with a low substrate specificity catalyzes the oxidation of various amino acids. Among the various amino acids, pyruvic acid can be generated from alanine only by the catalytic oxidative reaction of this oxidase. Therefore, in this study, the concentrations of D- and L-alanine were determined from the concentration of pyruvic acid, which was determined from the consumption of oxygen based on the oxidative reaction of pyruvate oxidase. From this point of view, there is a very strong possibility that biosensors utilizing enzymes with a low substrate specificity can be developed. The results obtained were as follows. (1) The optimum conditions for the use of pyruvic acid sensor were as follows: temperature of 25 degrees C, pH of 6.8, flow rate of 0.1 ml/min, thiamin diphosphate concentration of 1.5 mM, and injection volume of 50 microl. (2) D-Alanine and L-alanine optimally reacted with D- and L-amino acid oxidase at 30 degrees C, pH 8.2, for 30 min and at 37 degrees C, pH 7.8, for 90 min, respectively. (3) The linear relationships between the concentrations of D- and L-alanine and the output of the sensor were obtained at 3.56-106.8 microg of D-alanine and 5.34-71.3 microg of L-alanine. (4) The concentrations of D- and L-alanine in Meretrix iusoria, Patinopecten yessonsi, and Corbicula leana obtained by the proposed assay were in good agreement with those determined by a conventional method.     

Identification of developmental toxicants using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX)

Because growth and development are processes sensitive to the action of many chemicals, bioassays that screen for developmental toxicants may be more indicative of chronic effects than acute toxicity assays. FETAX is a 96 h whole embryo static renewal test employing the embryos of the frog Xenopus laevis. Endpoints are mortality, malformation and growth. Because of the frog's fecundity, its extensive use in basic research and the ability to obtain embryos year-round, it is an ideal organism to use in screening for developmental toxicants. By validating using known mammalian teratogens and the use of rat liver microsomes to stimulate mammalian metabolism, we have extended the use of the system for the prescreening of human developmental toxicants. In past validation work, we have correctly identified the teratogenicity of 15 to 17 compounds used in validation for a predictive accuracy of approximately 88%. In the present study, the ability of FETAX to detect developmental toxicants in groundwater samples taken from an industrial waste dump was evaluated. FETAX showed that it was sensitive enough to detect developmental toxicants in samples without prior concentration. In some samples, less than half the LC50 concentration was required to cause significant malformation. In some cases, a dose-response curve was not obtainable but the test results nonetheless indicated some developmental toxicity. The results of this study indicate that it is necessary to routinely screen for developmental toxicants when establishing water quality criteria for the preservation of species and for human health.     

Determination of protein absorption coefficients using a refractive index chromatographic monitor

Using lysozyme as a primary standard, a refractive index monitor designed for column chromatography was used to determined protein concentration and hence absorption coefficients. the method is non-destructive, requires only small amounts of protein 0.2 mg, and could be adapted for smaller samples.     

Constitutive changes in pigment concentrations: implications for estimating isoprene emissions using the photochemical reflectance index

The photochemical reflectance index (PRI), through its relationship with light use efficiency (LUE) and xanthophyll cycle activity, has recently been shown to hold potential for tracking isoprene emissions from vegetation. However, both PRI and isoprene emissions can also be influenced by changes in carotenoid pigment concentrations. Xanthophyll cycle activity and changes in carotenoid concentrations operate over different timescales, but the importance of constitutive changes in pigment concentrations for accurately estimating isoprene emissions using PRI is unknown. To clarify the physiological mechanisms behind the PRI–isoprene relationship, the light environment of potted Salix viminalis (osier willow) trees was modified to induce acclimation in photosynthetic rates, phytopigments, isoprene emissions and PRI. Acclimation resulted in differences in pigment concentrations, isoprene emissions and PRI. Constitutive changes in carotenoid concentration were significantly correlated with both isoprene emissions and PRI, suggesting that the relationship between PRI and isoprene emissions is significantly influenced by constitutive pigment changes. Consequently knowledge regarding how isoprene emissions are affected by both longer term changes in total carotenoid concentrations and shorter term dynamic adjustments of LUE is required to facilitate interpretation of PRI for monitoring isoprene emissions.     

Effect of chemical toxicants in a wide range of concentrations on the characteristics of lipids of mouse blood erythrocytes

The lipid composition of blood erythrocytes of mice at days 7 and 31 after a single per os administration of oily hexane-ester extracts with different contents of benzapyrene and polychlorobiphenyls in a wide concentration range was analyzed. It was shown that the parameters of the lipid metabolism in mouse blood erythrocytes depend on the dose of the extract in a nonlinear manner. The administration of extract 3 with a higher content of polychlorobiphenyls at a dose of 5.3 mg/kg and of extract M with a higher content of benzapyrene at the lowest dose of 5.3 x 10(-5) mg/kg had a more pronounced effect on the phospholipid composition of blood erythrocytes. It was shown that the magnitude and direction of changes in the structural state of erythrocyte membranes and the capacity of lipids for oxidation depend on the time elapsed after exposure, the chemical nature of the toxicants, and the dose of the extract.     

Determination of the metabolic index using the fluorescence lifetime of free and bound nicotinamide adenine dinucleotide using the phasor approach

The fluorescence lifetime of nicotinamide adenine dinucleotide (NADH) is commonly used in conjunction with the phasor approach as a molecular biomarker to provide information on cellular metabolism of autofluorescence imaging of cells and tissue. However, in the phasor approach, the bound and free lifetime defining the phasor metabolic trajectory is a subject of debate. The fluorescence lifetime of NADH increases when bound to an enzyme, in contrast to the short multiexponential lifetime displayed by NADH in solution. The extent of fluorescence lifetime increase depends on the enzyme to which NADH is bound. With proper preparation of lactate dehydrogenase (LDH) using oxalic acid (OA) as an allosteric factor, bound NADH to LDH has a lifetime of 3.4 ns and is positioned on the universal semicircle of the phasor plot, inferring a monoexponential lifetime for this species. Surprisingly, measurements in the cellular environments with different metabolic states show a linear trajectory between free NADH at about 0.37 ns and bound NADH at 3.4 ns. These observations support that in a cellular environment, a 3.4 ns value could be used for bound NADH lifetime. The phasor analysis of many cell types shows a linear combination of fractional contributions of free and bound species NADH.     

Respiratory response of cell-based sensors to toxicants measured by using pseudo-random signals

Cell-based sensors using such as Pseudomonas putida and Bacillus subtilis were applied to examine the toxicity of chemicals. Both toxicant and substrate solutions were introduced into the sensor system according to M-series and anti-symmetric M-series pseudo-random binary signals, Xn (n=15, minimal pulse width 4 min, period 60 min) and Yn (n=30, minimal pulse width 4 min, period 120 min). Toxicants such as Ag+, formaldehyde, azide, and hypo-chlorite were used to demonstrate the proposed method. The individual responses of substrate and toxicant were obtained at a time by calculating the cross-correlation function between the input and the output signals. Effects of toxicant on the response of substrate and the response of toxicant itself can be observed at a time, so that the method appears to be useful in studying the behavior of microorganisms in the presence of toxicants.     

Determination of plasma cell labelling index with bromodeoxyuridine using a double immunoenzymatic technique

Myeloma plasma cells were double stained using peroxidase and alkaline phosphatase labelled monoclonal anti-BrdU and anti-intracytoplasmic immunoglobulins. Samples were methanol fixed; DNA was denatured with formamide. The results allowed easy identification of plasma cells, their cytological examination and the calculation of percentage of plasma cells in S phase. Good correlation was found with the labelling index obtained with tritiated thymidine.