Studies on biochemical effects of nitrogen dioxide: I. Lipid peroxidation as measured by ethane exhalation of rats exposed to nitrogen dioxide

This research was in order to follow the periodic fluctuation of lipid peroxidation by a new method in rats exposed to nitrogen dioxide. Wistar male rats were examined for lipid peroxidation as demonstrated by ethane exhalation. In rats continuously exposed to 10 ppm nitrogen dioxide for 2 weeks, the amount of ethane exhaled fluctuated in a complex manner during the exposure. Ethane exhalation decreased slightly after the first day of exposure and then increased rapidly. The maximal values were observed after the fourth day of exposure and then decreased gradually to the initial level. Furthermore, the activity of glutathione peroxidase in lungs of rats exposed to 10 ppm nitrogen dioxide varied symmetrically against the change of ethane formation. Similar changes in ethane exhalation were observed in rats exposed to the lowest levels of nitrogen dioxide (0.4, 1.2 and 4.0 ppm) for 4 months. Compared to 10 ppm nitrogen dioxide exposure for 14 days, the characteristics in rats exposed to the low levels (0.4-4.0 ppm) of nitrogen dioxide were: the decline of ethane formation, the delay in alterations, and the tendency toward gradual increase during the longer period exposure.

Reaction of hemoglobin with nitric oxide and nitrogen dioxide in mice

The reaction of hemoglobin with NO and NO2 was compared in mice exposed to these cases. Nitrosyl hemoglobin (NOHb) and methemoglobin (MetHb) were determined simultaneously by electron spin resonance spectrometry at -140 degrees C. In mice exposed to 40 ppm NO, NOHb became constant (0.7%) in 30 min and declined rapidly with a half-life of several minutes when the mice were removed to room air. An increase of MetHb (5%) was also caused by exposure to NO and the time course was almost the same as that of NOHb. Exposure to 40 ppm NO2 produced only NOHb (0.2%); MetHb did not increase. The time course of NOHb was identical to that observed with NO exposure. Dose-effect relationships were determined with both gases at concentrations ranging from 20 to 80 ppm. A linear relationship could be observed between the concentrations of the gases and NOHb, but NO produced more NOHb than did NO2. There was an exponential increase of MetHb, particularly at high concentrations of NO.

Tubular structures in the cervix of mice experimentally infected with herpes simplex virus type 2

Experimental infection of the C3H/N mouse genital tract was demonstrated after intravaginal inoculation with herpes simplex virus type 2 (HSV-2). About 75% of the infected animals died by Day 7, and 75% of the surviving animals had severe vaginitis or neurological signs on Day 7. Titers of the virus recovered from vaginal secretions of infected animals reached a maximum on Day 2 and gradually decreased until Day 7. On the other hand, under the electron microscope, virus particles and tubular structures could be found in the nuclei of infected cells of the cervix in the 1st, 2nd and 4th days after infection. All cases in which virus particles could be found in the nuclei of infected cells were also positive for tubular structures and vice versa. These observations indicate that in situ diagnosis of HSV-2 infection can be made in the mouse model. The same method would be applicable for the diagnosis of human HSV-2 infection.

Studies on the biological effects of nitrogen oxides and photochemical oxidants

The animal studies in mice resulted as follows. Long-term exposure to NO2 at or above 0.5 ppm affected primarily the respiratory organs. The pulmonary effect of NO was slighter than NO2. Nitrosylhemoglobin formation in vivo was much smaller than in vitro strong affinity of NO with hemoglobin. The components other than O3 contained in the photochemically formed oxidant mixtures enhanced the effect of O3 alone. Symptoms of the patients seriously injured by photochemical smog in Japan suggested the different type in quality from the Los Angeles-type smog.

Effects of antimetabolites on the production of tubular structures in Vero cells infected with herpes simplex virus type 2

Treatment of Vero cells infected with herpes simplex virus type 2 with the proper concentrations of hydroxyurea (HU) reduced the production of infectious virus and markedly increased the accumulation of tubular structures in the nuclei when the drug was added within 6 hours after infection. Similar accumulation of tubular structures in the infected nuclei was also observed when infected cells were treated with phosphonoacetic acid at proper concentrations. The release of HU-treated, herpes simplex virus type 2-infected cells from the drug-induced blocking of synthesis of infectious virus resulted in the marked decrease of tubular structures coincidentally with the beginning of production of infectious virus. The data suggest the possibility that the disappearance of tubular structures may be related to the active production of infectious virus.

Production of tubular structures in Vero cells infected with herpes simplex virus type 2; effects of ultraviolet light irradiation and antimetabolites

In order to investigate the nature of tubular structures specifically found in herpes simplex virus type 2 (HSV-2)-infected cells, the multiplication of HSV-2 was studied in Vero cells cultured in the presence of varying concentrations of cytosine arabinoside (Ara-C) and cycloheximide (CH), inhibitors of DNA synthesis and protein synthesis respectively. Ara-C, at a concentration of 60 micrograms/ml, inhibited the multiplication of HSV-2 by more than 99% and also prevented the appearance of tubular structures and virus particles in the nuclei of infected cells. Nevertheless, the synthesis of virus specific surface antigens of HSV-2-infected Vero cells was not reduced, as revealed by the fluorescent antibody technique. On the other hand, 10 micrograms/ml of CH inhibited both the appearance of tubular structures and virus particles and the synthesis of virus specific surface antigens by more than 99%. These observations strongly suggest that the appearance of tubular structures is one of the late events in the process of virus multiplication. To measure the comparative genome size needed to produce membrane antigens, tubular structures and infectious centres, the effect of u.v.-inactivation of HSV-2 on these processes was studied. After u.v.-irradiation, the capacity to induce tubular structures was inactivated at a slower rate than the capacity to form infectious centres, but at a faster rate than the induction of surface antigens. Furthermore, more tubular structures could be induced by u.v.-inactivated virus than by the non-irradiated virus which was diluted to the same infectivity as the u.v.-irradiated virus. These results indicate that expression of the entire genome is not required for the production of tubular structures.

Optical diffraction analysis of electron microscope images of tubular structures found in cells infected with herpes simplex virus type 2

Optical diffraction analysis was done on the electron micrographs of tubular structures found in cells infected with herpes simplex virus type 2. By this method, the helical arrangement of subunits forming a tubular structure was demonstrated.

Electron microscope observations on tubular structures in cells infected with herpes simplex virus type 2

The fine structure of filamentous structures and lattice-like structures found in herpes simplex virus type 2-infected cells was studied. By specimen tilting experiments, it was demonstrated that the lattice-like structures were the cross-sectional views of the tubular structures and the filamentous structures were the longitudinal sections. The observation in negatively stained preparations of isolated tubular structures revealed that the structure was constructed by regular array of ring shaped elements. A hypothetical model is presented for tubular structures constructed on the basis of the present findings. The tubular structures appeared as early as 6 hours after infection and reached a maximum at 12 hours.

Prinzmetal's angina pectoris with normal coronary arteriograms

Four cases of variant angina pectoris with normal findings on coronary arteriogram were experienced. The facts may show that the existence of serious arteriosclerotic lesions in a major branch of coronary artery as pointed out by Prinzmetal is at least not essential for the occurrence of anginal attack in the present disease. But the finding that age and sex distribution of variant angina was nearly the same as that of effort angina seems to still indicate the possibility that arteriosclerotic lesion somehow participates in the mechanism of occurrence of the present disease.

Nitrosyl-hemoglobin formation in the blood of animals exposed to nitric oxide

Animals were exposed to nitric oxide (NO) in order to study its biological effect. First a method was developed to exclude nitrogen dioxide formed during exposure of NO. Nitrosyl-hemoglobin (NOHb) in the blood of mice, rats, and rabbits exposed to NO was determined by electron spin resonance spectrometry at -100C. The content of NOHb in the blood of the mouse reached the maximum (0.13% of the total hemoglobin) 20 minutes after the exposure was begun and thereafter a state of equilibrium was maintained. The NOHv level decreased to one half in several minutes after the mouse was removed to a filtered air environment. Dose-response relationship was observed between gas concentrations and the maximum NOHb level.