The problem of genetic-biochemical basis of individual sensitivity in occupational medicine

Human sensitivity to various factors of occupational environment (toxic chemicals, aerosols with mostly fibrogenic effects, etc.) depends on individual hereditary features determining adaptation or dysadaptation with subsequent disease. Studies of propensity and resistance in individuals exposed to occupational hazards should cover analysis of genetic basis for polymorphism in certain biochemical systems determining relationships between hazards detoxication and activation, DNA alteration and repair.     

Spatial electrical patterns in simulated neuronal dendrites

Steady state longitudinal distributions of (a) the density of channels conducting an inward transmembrane current of cations, (b) the submembrane concentrations of these cations, and (c) the resting membrane potential, were investigated in a phenomenological model of a cylinder-shaped dendritic process of the neuron. It was found that spatially non-uniform patterns of these distributions occur only if one of the following conditions held (i) an increase in the intracellular concentration of cations conducting an inward passive transmembrane current amplified the active efflux of those cations by the pump and attenuated their passive influx through the voltage dependent channels, with amplification of the efflux lower than attenuation of the influx; (ii) molecules of mobile channels bore a negative electrophoretic charge exposed to the intracellular space and were subject to lateral electrodiffusion in the membrane; (iii) the cations induced a further release of cations from intracellular stores. Numerical simulation studies of the membrane with Na and K channels and Na/K pumps with conditions (i) and (ii) have demonstrated the possibility of the creation of inhomogeneous patterns in the neurites. These inhomogeneous patterns are dissipative structures (DSs), and they can be spatially periodic.     

Textural and Chemical Characteristics of Recombined Precooked Beef Chuck Roasts as Influenced by Boning Time and Salt Level

The effects of hot-boning (HB) and salt level (SL) (0, 0.5, 1.0%) on recombined precooked roasts from three beef chuck recombined whole muscles were investigated using a system that employed electrical stimulation, blade tenderization, vacuum massage and the addition of phosphate. SL and muscle type (MT) significantly affected proximate composition (protein, fat and moisture). Maximum yields were obtained with hot-boned treatments at the highest salt level. Instron measurements were affected by MT, HB and SL. Results of this study indicate that binding of large meat pieces together to form low calorie recombined, precooked roasts can be achieved.     

Changing pattern of respiratory tuberculosis in the UK in adult patients from the Indian subcontinent

BACKGROUND: Clinical observations over a 12 year period have suggested a changing pattern of adult respiratory tuberculosis in patients from the Indian subcontinent in two districts of the United Kingdom with a high incidence of tuberculosis. METHODS: Details of all patients for the period 1981-92 residing in the Newham and Blackburn districts aged 15 and over whose ethnic origin was from the Indian subcontinent (n = 1308) were analysed by stepwise logistic regression to determine the relationship between sputum smear positivity, sputum culture positivity, and isolated mediastinal lymphadenopathy, year of notification, age, sex, ethnic group (Indian or Pakistani), and whether the patient had visited the Indian subcontinent within the last three years. RESULTS: The proportion of cases who were smear positive rose over the 12 years of the study, as did the proportion of culture positive cases. The proportion with isolated mediastinal lymphadenopathy fell. These changes took place in both districts. They were not explained by demographic changes in age, sex, or ethnic group, nor was there evidence that smear and culture positivity increased in those who had recently visited India or Pakistan. CONCLUSIONS: The pattern of tuberculosis in adult patients originating from the Indian subcontinent has altered over time towards that seen in the white population in the UK.     

Stability and oligosaccharide binding of the N1 cellulose-binding domain of Cellulomonas fimi endoglucanase CenC

Differential scanning calorimetry has been used to study the thermal stability and oligosaccharide-binding thermodynamics of the N-terminal cellulose-binding domain of Cellulomonas fimi beta-1,4-glucanase CenC (CBDN1). CBDN1 has a relatively low maximum stability (delta Gmax = 33 kJ/mol = 216 J/residue at 1 degree C and pH 6.1) compared to other small single-domain globular proteins. The unfolding is fully reversible between pH 5.5 and 9 and in accordance with the two-state equilibrium model between pH 5.5 and 11. When the single disulfide bond in CBDN1 is reduced, the protein remains unfolded at all conditions, as judged by NMR spectroscopy. This indicates that the intramolecular cross-link makes a major contribution to the stability of CBDN1. The measured heat capacity change of unfolding (delta Cp = 7.5 kJ mol-1 K-1) agrees well with that calculated from the predicted changes in the solvent accessible nonpolar and polar surface areas upon unfolding. Extrapolation of the specific enthalpy and entropy of unfolding to their respective convergence temperature indicates that per residue unfolding energies for CBDN1, an isolated domain, are in accordance with those found by Privalov (1) for many single-domain globular proteins. DSC thermograms of the unfolding of CBDN1 in the presence of various concentrations of cellopentaose were fit to a thermodynamic model describing the linkage between protein-ligand binding and protein unfolding. A global two-dimensional minimization routine is used to regress the binding enthalpy, binding constant, and unfolding thermodynamics for the CBDN1-cellopentaose system. Extrapolated binding constants are in quantitative agreement with those determined by isothermal titration calorimetry at 35 degrees C.