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Biomedical subjects

S Yoshihara

Publications and source records attributed to S Yoshihara.

At least 145 records · Page 8Linked to original sources
PubMed1983

White spots of the liver in pigs experimentally infected with Ascaris suum.

To make clear the relationship between Ascaris suum infection and the appearance of white spot lesions on the surface of the liver in pigs, three groups of pigs were inoculated orally with embryonated A. suum eggs and observed clinicopathologically. Group A of three pigs were inoculated 21 times with 100 eggs each of the nematode, group B of three pigs 4 times with 50,000 eggs each for 10 weeks, and group C of two pigs 2 times with 50,000 eggs each at a one-week interval. All the pigs were sacrificed at the same time 1 week after the final inoculation. Such signs of the nematode infection as dyspnea, coughing and fever appeared in all the pigs of groups B and C seven days after inoculation to continue for several days. In addition, peripheral blood eosinophilia was recorded in these animals 7 or 14 days after inoculation. At autopsy, mesh-worked white spots, some compact and others lymphonodular, were observed on the surface of the liver in all the pigs of the three groups. Main white spots were mesh-worked and lymphonodular in the pigs of group A. They were severe and compact in group B. Therefore, they were rough to the touch. In group C mesh-worked white spots fused with one another and covered the surface of the liver. These white spot lesions observed were morphologically very similar to those found in the field conditions. Complement-fixating antibodies reacting to adult A. suum antigen were detected only in sera from the pigs of group B. Moreover, antibodies involved in the intradermal reaction of immediate type were found in the pigs of groups A and B.

Animals↗
PubMed1983

Pathological studies on white spots of the liver in fattening pigs.

Hepatic lesions were found in fattening pigs derived from a farm where swine had been suffering from the multiple occurrence of white spots in the liver. They were examined at a slaughter-house for 18 months. The white spots were classified into three patterns on the basis of the macroscopic appearance; that is a compact, a mesh-worked, and a lymphonodular pattern. Histologically, the following 3 kinds of lesions were seen: (1) Eosinophilic interstitial hepatitis accompanied with intralobular necrosis, arteriolar degeneration, boring focus, granuloma and the existence of Nematoda larvae. (2) Fibrosis accompanied occasionally with infiltration of a few eosinophils and lymphocytes. (3) Lymphofollicular hyperplasia. As to the relationship between macroscopic and histologic patterns, compact white spots were generally produced by eosinophilic interstitial hepatitis. The mesh-worked pattern consisted of eosinophilic interstitial hepatitis or fibrosis, and the lymphonodular pattern of lymphofollicular hyperplasia. The incidence of eosinophilic interstitial hepatitis was relatively high over a period from July to December and rather low over a period from January to June. That of fibrosis was considerably high all the year round. Lymphofollicular hyperplasia showed no distinct seasonal incidence. Intestinal ascarids were frequently detected over a period from August to October. Pigs having CF antibody against Ascaris suum increased in number over a period from August to December. From these results, the cause of the multiple occurrence of white spots in the liver was regarded as A. suum infection.

Animals↗
PubMed1982

Involvement of endogenous digitalis-like substance in genesis of deoxycorticosterone-salt hypertension.

In an attempt to evaluate the role of endogenous digitalis-like substance in the genesis of deoxycorticosterone (DOCA) -salt hypertension, the effects of intravenous anti-digoxin antibody on the blood pressure response were observed in male Wistar rats that underwent heminephrectomy followed by treatment with DOCA and saline. Administration of anti-digoxin antibody caused a marked decrease in the blood pressure which continued for about an hour. Such a change in the blood pressure was not observed in pertinent control animals. Thus, it seems that endogenous digitalis-like substance plays an important role in the genesis of DOCA-salt hypertension.

Animals↗
PubMed1982

A unique change of steroid metabolism in rat liver microsomes induced with highly toxic polychlorinated biphenyl(PCB) and polychlorinated dibenzofuran(PCDF).

Pretreatments of rats with the highly toxic compounds such as 3,4,5,3',4'-pentachlorobiphenyl(PenCB), and 2,3,7,8-tetrachloro(TCDF) and 2,3,4,7,8-pentachlorodibenzofuran(PenCDF), which are potent 3-methylcholanthrene(MC)-type inducers, increased selectively 7 alpha-hydroxylation, but strongly suppressed 2 alpha-, 6 beta- and 16 alpha-hydroxylations as well as 5 alpha-reduction of progesterone and testosterone in the liver microsomes. This unique change in the metabolic pattern was accompanied by a marked decrease in total metabolism of both steroids and appeared to correlate apparently with their toxic potency. This kind of change was not shown by pretreatments with not only MC itself but also the phenobarbital-type(2,4,5,2',4',5'-hexachlorobiphenyl) and the mixed type PCBs(Kanechlor 400, a PCB mixture with 48% chlorine content), all of which possess only a low acute toxicity. The metabolic change produced by 3,4,5,3',4'-PenCB, 2,3,7,8-TCDF and 2,3,4,7,8-PenCDF might not be due to their stimulatory or inhibitory effects, because when added to the incubation mixture 3,4,5,3',4'-PenCB did not change the metabolic pattern with MC-microsomes to that with 3,4,5,3',4'-PenCB-microsomes. Furthermore, either 2,3,7,8-TCDF or 2,3,4,7,8-PenCDF gave similar metabolic pattern whereas their residual levels in the liver were greatly different from each other at the time of sacrifice. These results suggest that this kind of unique change of the steroid metabolism produced by highly toxic PCBs and PCDFs may be responsible, at least in part, for the endocrine symptoms caused by these compounds via disturbance of steroid homeostasis.

Animals↗
PubMed1979

Possible correlation between induction modes of hepatic enzymes by PCBs and their toxicity in rats.

Acute toxicity of individual PCBs, which were categorized as either phenobarbital (PB)- or 3-methylcholanthrene (MC)-type inducers, was examined in young male Wistar rats, comparing their effects on growth rate, organ weight and liver lipid content, 5 days after a single i.p. injection. PB-type PCBs (2,4,3',4'- and 2,5,2'5'-tetrachlorobiphenyl), which slightly increased a content of cytochrome P450, did not show any significant toxicity at a dose of 100 mg/kg. On the contrary, MC-type PCBs (3,4,5,3',4'-pentachloro- and 3,4,5,3',4',5'-hexachlorobiphenyl), which markedly increased a content of cytochrome P448, strongly reduced growth rate and weights of thymus and spleen at a dose of 10 mg/kg. Liver enlargement accompanied by fatty liver was also observed only with MC-type PCBs. 3,4,3',4'-Tetrachlorobiphenyl was also toxic at a dose of 50 mg/kg, in keeping with its weak MC-type-inducing ability. Pretreatment with MC affected neither growth rate, spleen weight, nor liver lipid content. These results suggest that the toxic potency of PCBs is related to their MC-type inducing ability, but the toxic characteristics are different from those of MC itself.

Animals↗
PubMed1975

Appearance of Fasciola cercariae in rice fields determined by a metacercaria-detecting buoy.

The appearance of Fasciola cercariae in aquatic rice fields of fluky areas was investigated by using a metacercaria-detecting buoy. The buoy consisted mainly of a foam styrol disk 10 cm in diameter and 3 cm in thickness, and a polyethylene sheet 16 cm in diameter covering the bottom and side of the disk. Each buoy was floated at each corner of a section of rice fields. To determine the serial appearance of Fasciola cercariae, the polyethylene sheet was renewed at intervals of a week over a period of rice cultivation and the number of metacercariae was counted on each sheet. In most rice fields an evident peak of metacercarial detection was observed between the middle of July and the end of August. The time of the first detection of cysts in a small number varied from one section to another of the same field or from one area to another. Metacercariae decreased in number in accordance with drying up the fields. The metacercaria-detecting buoy method was applied to rice fields fertilized with cattle manure for 7 days in mid-summer, as well as to fields located closely to cattle pens, but not fertilized. Many cysts were detected from both groups of fields. The results obtained from weekly observation on the population of snails, particularly infected snails in their habitats, and those from the cercarial appearance detected by means of the buoy method were essentially the same.

Animals↗