Epidemiology of chronic, precancerous and oncologic diseases in workers of asbestos and cement industry

Hygienic, clinical and epidemiologic screening was performed in staff of asbestos and cement goods production enterprise. Various dystrophic processes of pharynx and nasal cavity appeared to prevail among upper respiratory tract diseases. Average exposure to dust during 22 years at the stated production can lead to asbestosis 0-I stage, average exposure during 20.5 years can result in dust bronchitis and occupational allergic dermatosis can result from average exposure to dust during 21 years. Retrospective cohort study of mortality within 1949-1988 failed to find oncologic risk in workers engaged into asbestos and cement goods production higher than in general population.     

Acid-base properties of the polyene antibiotic nystatin

The acid-base properties and transformation of nystatin in water, methanol, 80 per cent ethanol, 70 per cent propanol and 70 per cent dimethylsulfoxide were studied. The data are indicative of a significant difference in the protolytic properties of the antibiotic in various solutions. Nonreversible conformative conversions of nystatin in water and methanol not connected with the loss of the antibiotic activity were observed. It is suggested that the molecule of nystatin in the above solutions could be in 3 main states, i. e. inert native and activated. The results of the study may be of use in development of the schemes for isolation of nystatin from the mycelium preparation of some of its water soluble forms.     

Determination of calcium binding sites in gas-phase small peptides by tandem mass spectrometry

Low-energy (LE) and high-energy (HE) collisionally activated decompositions (CAD) of calcium/peptide complexes of the form [M - H + Ca]+ and [M + Ca]2+ reflect the site of calcium binding in various gas-phase peptides that are models of the calcium binding site III of rabbit skeletal troponin C. The Ca2+ binding sites involve an aspartic acid, glutamic acid, and asparagine, which are in the metal-binding loops of calcium-binding proteins. Both fast atom bombardment (FAB) and electrospray ionization (ESI) were used to generate the metal/peptide complexes. When submitted to LE CAD, ESI-produced Ca2+/peptide complexes undergo fragmentations that are controlled by Ca2+ binding and provide information on the Ca2+ binding site. The LE CAD spectra are simple, indicating that Ca2+ binding involves specific oxygen ligands including acidic side chains and that only a few low-energy fragmentation channels exist. The HE CAD spectra of FAB-produced Ca2+/peptide complexes are more complex, owing to the introduction of high internal energy into the precursor ion. Interactions of the other alkaline-earth metal ions Mg2+ and Ba2+ with these peptides reveal that the ligand preferences of these metal ions are slightly different than those of Ca2+.     

Ferrireductase from Pichia guilliermondii: properties and regulation of activity and synthesis

Iranian Jews represent an ancient community with a very high degree of inbreeding. Although the community remained relatively isolated, it had strong ties with Babylonian Jewry in Iraq. Several genetic disorders have been reported to be frequent among Iranian Jews, in particular, corticosterone methyloxydase deficiency type II, polyglandular syndrome, and rimmed vacuole myopathy. Based on the data collected in our clinic, recessive and dominant deafness also appear to be frequent. Other diseases, such as beta-thalassemia, achromatopsia, colobomatous microphthalmia, Dubin-Johnson syndrome, and congenital myasthenia gravis, were frequent in both the Iranian and Iraqi Jewish communities. The place of origin of the families within Iran and the results of molecular studies suggest some reason(s) for the high frequency of these disorders among Iranian Jews. While the high frequency of some of the disorders, such as corticosterone methyloxydase deficiency type II, represents a founder effect, in other diseases (such as beta-thalassemia) it was secondary to heterozygote advantage.     

Human placenta barrier remodelling under different type of hypoxia

The stereological investigation was performed on intermediate and terminal villi of placenta obtained from each of the following conditions: high altitude (up to 2800 m), maternal anemia and EPH-gestosis. These conditions were taken to represent hypoxic, anemic and ischemic hypoxia, respectively. In each situation there was a trend for both the volume of trophoblast and stroma to be lower than in controls with accompanying increase in the volume fraction of fetal capillaries, although the differences were statistically significant only for cases of hypoxic and anemic hypoxia. The capillary diameter was higher in EPH-gestosis group. There was no evidence of "hypercapillarization" of the villi because the relative capillary length was constant in all the groups. The harmonic mean thickness in anemia and altitude groups was reduced. As a result a specific and morphometric (per 1 kg of fetal weight) diffusing capacity was maintained at the control level, but at the altitude group it was even higher. These results suggest that placenta barrier remodelling is the principal mechanism of adaptation to different forms of hypoxia.     

Inclusions,Stress Concentrations and Surface Condition in Bending Fatigue of an H13 Tool Steel

Combined effects of inclusions, surface condition and geometrical stress concentration on the fatigue strength of a tool steel have been studied. Bending fatigue testing was performed for milled tool components and smooth specimens produced from an experimental AISI H13 tool steel with varying additions of sulphur and oxygen. Inclusion distributions of the different test series were determined. Fracture surfaces after fatigue failures were studied in a scanning electron microscope. The sulphur content does not have a significant influence on the fatigue strength of the milled tool components in the range of 0.02 ‐ 0.09 wt%. A clear reduction in the fatigue strength is obtained for the smooth specimens when the steel becomes rich in inclusions. Here, the oxide type inclusions dominated as crack initiators and the effect of sulphides was smaller. The results demonstrate the reduced effect of inclusions on the fatigue strength in components with large stress concentrations and rough surfaces.