For the elucidation of methemoglobinemia in industrial poisonings caused by aromatic nitro and amino compounds, the study on the mechanism of methemoglobin (metHb) formation by aminophenol and diphenol in vitro has been carried out1). In this paper, the metHb formation in vivo by the above phenols was investigated to ascertain whether the mechanism of the metHb formation in vivo is similar to that in vitro or not. Methemoglobinemia was produced by the administration of o- or p-aminophenol as in vitro study, but no methemoglobinemia was observed by any isomers of diphenol, though pyrocatechin and hydroquinone were found to be the strong metHb formers in vitro as aminophenols. Characteristic of methemoglobinemia by aminophenol was com-pared with those of methemoglobinemia by nitrobenzene, aniline, p-benzoquinone and others. As the results of this study, it was ascertained that methemoglobinemia by aminophenol in vivo was produced by its quinone body formed mainly by the oxidase action of perturbed hemoglobin and not by autoxidation.
In the previous papers, 1, 2) an induction period was observed in the oxidation processes of oxyhaemoglobin to methaemoglobin by sodium nitrite and the mechanism of the reaction was cleared kinetically. In the present report, effects of various substances, which have been reported to be effective on the physiological function of haemoglobin molecule, on the oxidizing reaction by sodium nitrite were studied. When the time length of the induction period was represented as τ (seconds) and the oxidation velocity in the methaemoglobin formation period as υ (μM of methaemoglobin formed/sec), the above mentioned substances used were classified in to the following four types. 1. Substances which cause the change of only τ. 2. Substances which cause the change of τ and υ. 3. Substances which cause the change of only υ. 4. Substances which don't cause the change of either τ or υ. Substances belonging to the type 3 have not been found out. Such substances should not be found out, because, if the reaction occurs according to the mechanism proposed by us, 1) the change of υ always accompanies with that of τ. The values of τ and υ of inpatients with various diseases were in a wide deviation comparing with those of the healthy. This deviation seen in the inpatients was assumed to be caused by various medicaments pre-scribed in the hospital. Since the oxidation of oxyhaemoglobin by sodium nitrite was influenced by various substances, it was assumed that the estimation of τ and υ value in the oxidizing reaction might be used as a method for early detection of some occupa-tional diseases.
Effect of nitroglycol on mitochondria prepared from rabbit liver was investigated using the technique of manometric method in the presence of various substrates belonging to citric acid cycle. The amount of oxygen consumed by mitochondria decreased about 10 percent by the addition of 0.05-500μM of nitroglycol and about 70 percent by the addition of 5000μM of the poison. This fact may indicate that the structure of mitochondria was partially damaged by nitroglycol and as the result of this damage enzymes contained in the particles were inactivated. In conformity with these experiments, the possibility that mitochondria in the liver or heart cells of animals is damaged directly by nitroglycol penetrated into the tissue cells from the blood was discussed.
For the purpose of understanding the mechansim of haemolysis caused by various substances, the comparison of haemolytic action of various substances was carried out from the relation between the concentrations of substances and the incubation time with red blood cell. The phenomenon of haemolysis caused by various substances could be divided into two groups. The first group is haemolysis produced by the substances such as surface detergent, alcohols, urea and tauroglycocholate, and the difference between the concentra-tion producing complete haemolysis and that causing scarce haemolysis is very narrow. Haemolysis of the second group shows a very wide range of concentration, and is pro-duced by metals and organometallic compounds. The difference of mechanism of haemolysis caused by thosetwo groups was discussed. The comparison of haemolytic action by chemical compounds having similarstructure was also studied.
Coproporphyrin determination by the Askevold method is simple, easy and inexpensive.Coproporphyrin determination may be better than urinary lead analyses when well equipped laboratories and technicians with experienced training are not available, especially in small industries or perhaps in developing countries. For the screening periodic examination of lead workers to obtain information of lead exposure, and to prevent lead poisoning of those workers, it was demonstrated in the present study that one might skip urinary lead analyses which should be carried out for suspected cases. Because urinary coproporphyrin increase nicely paralleled that of lead, and in the copro-porphyrin determination there could be considered no such fear of contamination or analytical errors which might yield in the determination of urinary lead. According to the combined observations of the present as well as the previous study, the threshold limit value of lead in air was assumed to be around 0.08 to 0.12mg/m3 for coproporphyrin increase. In mercury absorption coproporphyrin was found to increase tosome extent, and mercury exposure as a group will be detected by plotting data on paper of logarithmic normal probability, provided a standard distribution curve obtained from normal subjects.
Accurate knowledge of mineralogical composition of the dust from the lungs should be helpful for understanding pathological changes of pneumoconiosis. The dust from the lungs of refractory workers in silica refractory industry is composed mainly of quartz, tridymite and cristobalite. This paper describes a rapid X-ray diffractometer method for quantitative determination of quartz, tridymite and cristobalite in the dust from the lungs. Pure standards of quartz, tridymite and cristobalite were produced and several mixtures of these were prepared. The diffraction patterns of each pure member and of the mixtures were recorded with an X-ray diffractometer in the range of 4.5Å--3.3Å at a slow scanning speed. The diffraction pattern of the dust from the lungs was recorded and compared with the standard patterns mentioned above. The weight percentage of each mineral was calculated on the basis of the intensity ratio of the 3.35 Å quartz peak, the 4.04 Å cristobalite peak and 4.31 Å tridymite peak.
The phosphoric acid method for the determination of free silica mixed in silicates was improved in its reproducibility by applying the copper mantle as a heat radiator. The superiority of this method to the electric heater method was proved by the observa-tion of the dissolution velocities of several kinds of quartz samples using the two methods. The dissolution velocities were studied on quartz powders which were produced by three different methods by observing their dissolution in hot phosphoric acid using copper mantle and it was cleared that the surface of quartz powder was denaturalized by the grinding of quartz and this part was dissolved in phosphoric acid with far higher velocity than the original quartz. The appearances of these quartz were observed before and after the treatment with phosphoric acid under the optical microscope, and the denaturalized surface was demonstrated clearly by the phase contrast microscope with polarizer. The obtained value of non-soluble part in phosphoric acid had been taken as free silica but the observations in this experiment showed that the part of quartz denatura-lized during the grinding was soluble and this part was accounted as non-free silica.
Characteristics of the Digital Dust Indicator were examined, and the following equation was derived to express the response R of it, R=Kσ(C/P)exp.[-θ(C/P)] where K is the constant, σ is the relative scattering coefficient of dust, p is the dissipa-tion coefficient of dust particles, θ is the linear function of the extinction coefficient of particles and C is the mass concentration of dust. And usefulness of this equation was examined experimentally. It was found that values of p were proportional to product of density and meandiameter of particles. Regarding values of θ, almost the same values were obtained for all samples tested regardless the difference in particle size and colour or dusts. Calculated values of Kσ obtained for various dusts vary with colour of dust. From these experiments, it was proved that the equation was sufficiently useful toexpress the relation between the dust concentration and the response of the Digital Dust Indicator. The practical method to evaluate the dust concentration in air by the Digital Dust Indicator was discussed.