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Biomedical subjects

H Tsukada

Publications and source records attributed to H Tsukada.

At least 235 records · Page 13Linked to original sources
PubMed1984

Enhancement of nucleolar RNA synthesis by chromium (III) in regenerating rat liver.

Rats pretreated with CrCl3 at an intraperitoneal dose of 5 mg Cr/kg body weight, and then subjected to partial hepatectomy concentrated Cr in the regenerating liver cells, especially in the nucleoli. Hepatic RNA synthesis induced by partial hepatectomy was further enhanced by Cr(III) administration without changes of the nucleotide pool size at least for 12 hr after the hepatectomy. Of the RNA species newly synthesized, the synthesis of nucleolar RNA was predominantly enhanced. The nucleolar RNA thus synthesized in the regenerating liver of Cr(III)-dosed rats followed normal processing into rRNA as estimated by actinomycin D-chase experiments followed by sucrose density gradient centrifugation analysis and also by nucleotide composition analysis of nucleolar and ribosomal RNAs. These results suggest that Cr accumulated in nucleoli may participate in nucleolar gene expression.

Animals↗
PubMed1984

Serum thyroglobulin concentration in normal pregnancy.

We measured the levels of serum thyroglobulin (Tg) in 52 pregnant females at various stages and compared them with those of 15 age-matched nonpregnant females. Serum Tg was measured by a solid-phase immunoradiometric assay. In pregnant females, mean serum Tg levels at the first, second, early third, and late third trimesters were 8.4 (range; 1.3-18.0), 9.2 (1.7-25.6), 10.1 (1.8-22.8), and 12.1 ng/ml (5.3-25.2), respectively. The statistical comparison was made after logarithmic transformation of the data. The mean value only at the late third trimester was significantly higher than that of controls (mean; 6.0 ng/ml, range; 1.5-23.6), but each value was within the normal range. Although serum Tg levels have been reported to be high at the end of pregnancy, our results indicate that the Tg levels in females could be clinically interpreted without regard to the coexistence of pregnancy.

Adult↗
PubMed1983

The role of tissue thromboplastin in the development of DIC accompanying neoplastic diseases.

Procoagulant activity of gastric cancer tissues and leukocytes obtained from various types of leukemia have been studied with special reference to TTP. The following results were obtained. Homogenates of APL leukocytes and gastric cancer tissues contained strong procoagulant activities, most of which have been identified as TTP since the activities were neutralized by a specific antibody against purified human placenta TTP, inactivated by the removal of phospholipid with heptane-butanol mixture, and inactivated by the addition of phospholipase C. The delipidated homogenates regained procoagulant activities by relipidation procedures. These results also confirmed that TTP from APL leukocytes and gastric cancer tissues have the same lipoprotein properties as those of TTP in normal tissues. Though slight proteolytic activity and fibrinolytic activity were demonstrated in the homogenate of gastric cancer tissues, it was noted that the TTP activity was different from these two activities by partial purification of TTP from gastric cancer tissues. The TTP activity of 9 homogenates of gastric cancer tissues was 301 +/- 289 (mean +/- SD) units per mg protein, being higher in homogenates of mucinous adenocarcinoma and signet-ring cell carcinoma than in those of tubular and poorly differentiated adenocarcinoma. The mean TTP activity of leukocyte homogenates from 14 patients with APL and one out of 4 patients with CML in blastic crisis was 81 +/- 76 units/10(7) cells. The TTP activity of the homogenates of leukocytes from 7 out of 18 patients with AML and another patient with CML in blastic crisis ranged from one to six units/10(7) cells with a mean of 3.3 +/- 1.2. The TTP activity of leukocyte homogenates from the other 11 cases of AML, two cases of CML in blastic crisis, 6 cases of CML, and one case each of ALL and CLL were less than one unit/10(7) cells. In leukemic patients, all cases with a value of more than 202 for the product of units of TTP activity per 10(7) cells and differential count (%) of leukemic cells in the bone marrow smear (MU value) were accompanied by DIC. The MU value of leukemic patients correlated well to the plasma fibrinogen and serum FDP levels. All patients with a MU value of more than 277 died of DIC when a sufficient amount of heparin was not administered. On the other hand, no DIC developed in any of the patients with a MU value of less than 90.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Coagulation↗
PubMed1983

Subcellular distribution of 3H-digitoxin and its metabolites in the hearts of the cats with a hypersensitivity to the drug.

To clarify the cause of hypersensitivity to digitoxin, an experiment was carried out with cats. The most potent hypersensitivity to digitoxin has been observed 48 hr after the injection of a loading dose. However, 1 hr after this injection, the cats failed to show the hypersensitivity. One, 24 and 48 hr after the injection of 3H-digitoxin, the contents of digitoxin and its metabolites in subcellular fractions of hearts were measured. Digitoxin contents in microsomal fractions 48 hr after the injection only slightly decreased. while those in mitochondrial and nuclear fractions markedly decreased as compared with the check at 1 hr. An increase of sodium ions and a decrease of potassium ions in the hearts were seen 48 hr after the injection. These facts may be related to the cause of hypersensitivity.

Animals↗
PubMed1983

Effects of phenobarbital-feeding on the phalloidin-sensitivity of rat hepatocytes.

Male F344 rats were continuously fed 0.05% phenobarbital (PB)- or 0.02% 2-acetylaminofluorene (2-AAF)-containing diet for 3 or 8 weeks. The hepatocytes were isolated by a collagenase-perfusion technique and changes in the phalloidin-sensitivity of the cells were examined. After an 8-week treatment with PB or 2-AAF, the phalloidin-sensitivity, in terms of formation of cytoplasmic blebs over the cell surface, was reduced significantly in both groups. The degree of insensitivity to phalloidin induced by PB was found to be similar to that induced by 2-AAF. Two weeks after cessation of the PB-feeding, the sensitivity had recovered to the control range, while the decreased sensitivity induced by 2-AAF persisted for at least 2 weeks after the cessation of 2-AAF-feeding. Furthermore, cytochemical examinations of normal and 2-AAF-treated hepatocytes revealed that the degree of sensitivity decreased in the order of normal hepatocytes, 2-AAF-treated gamma-glutamyl transpeptidase-negative hepatocytes, and 2-AAF-treated gamma-glutamyl transpeptidase-positive hepatocytes. The decreased sensitivity of the latter two cell types also persisted for 2 weeks after the cessation of carcinogen treatment.

2-Acetylaminofluorene↗
PubMed1983

Elevation of gamma-glutamyl transpeptidase activity in rat liver induced by feeding of butylated hydroxytoluene.

The effect of butylated hydroxytoluene (BHT) on gamma-glutamyl transpeptidase (GGT) activity in F344 rat liver was investigated. GGT activity was significantly higher after the 1st week of BHT feeding than in control rats, and the high activity was maintained until BHT feeding was stopped. Four weeks after the cessation of an 8-week course of BHT feeding, there was no difference in liver GGT activity between control rats and BHT-treated rats. Histochemical analysis showed that GGT-positive hepatocytes appeared in periportal areas of the liver lobules in BHT-treated rats.

Animals↗
PubMed1982

In vitro measurement of resistance to phalloidin and gamma-glutamyltransferase of carcinogen-induced preneoplastic hepatocytes of rats.

Male inbred F344 rats weighing about 150 g were fed continuously a diet containing 0.02% N-2-fluorenylacetamide for 14-15 weeks. The presumptively preneoplastic hepatocytes were transferred to an in vitro system after dispersion by a collagenase-perfusion technique. Sensitivity to phalloidin in terms of formation of cytoplasmic blebs on the cell surface was less in the presumptively preneoplastic hepatocytes than in normal hepatocytes. Among the presumptively preneoplastic hepatocytes, the gamma-glutamyltransferase (GGT)-positive cells were less sensitive to phalloidin than GGT-negative cells, indicating a greater contribution to the decrease in the sensitivity to phalloidin of the presumptively preneoplastic cells.

2-Acetylaminofluorene↗
PubMed1982

Matrical inclusions of peroxisomes induced by clofibrate in preneoplastic hepatocytes of rats fed 3'-methyl-4-dimethyl-aminoazobenzene.

The response of peroxisomes to clofibrate in preneoplastic hepatocytes of rats fed 3'-methyl-4-dimethylaminoazobenzene was examined histochemically (using the 3,3'-diaminobenzidine reaction) and electron microscopically. Morphometrical examinations revealed that the number of peroxisomes correlated well with the intensity of the histochemical reaction. Preneoplastic hepatocytes which responded to clofibrate with a marked proliferation of peroxisomes showed no matrical inclusions or merely matrical plates in very low incidence in the proliferated peroxisomes. The cells that exhibited a moderate proliferation of peroxisomes showed formation of peroxisomal matrical inclusions in high incidence. The inclusions were matrical plates and tubules showing the same fine structures as those found in 2-acetylaminofluorene carcinogenesis. These peroxisomal inclusions were absent in the cells which responded to clofibrate with no or only a slight increase in the number of peroxisomes. It is suggested that these varieties of peroxisomal changes might reflect the progress of preneoplastic phases of the cells.

Animals↗
PubMed1982

Primary culture of preneoplastic hepatocytes from rats treated with 2-acetylaminofluorene and clofibrate: relationship between resistance to dimethylnitrosamine and responsiveness of peroxisomes.

Hepatocytes of 2-acetylaminofluorene-induced hyperplastic nodules of rats treated with clofibrate were transferred to primary culture after dispersion by a collagenase perfusion technique. After 48-hr treatment with dimethylnitrosamine (DMN), the resistance to the agent of the cells forming rod-shaped peroxisomes was examined. Catalase activity of the DMN-resistant cells was also determined. At concentrations of 10(-3)M and 10(-4)M DMN, the resistant cell population of hepatocytes with rod-shaped peroxisomes was larger than that of the cells without abnormal peroxisomes. On the other hand, the catalase activity of the attached cells that remained after DMN treatment decreased as the concentration of DMN was increased. The cells showing a stronger induction of the enzyme activity were found to be more sensitive to the cytotoxicity of DMN and they became detached from the culture dishes.

2-Acetylaminofluorene↗
PubMed1982

Hepatocytes with extraperoxisomal catalase in rats fed 3'-methyl-4-dimethylaminoazobenzene.

Histochemical and cytochemical studies were done to further characterize the preneoplastic hepatocytes with extraperoxisomal catalase (EPC-cells) that were found in the livers of rats fed 3'-methyl-4-dimethylaminoazobenzene. Catalase activity was demonstrated cytochemically to be localized in nuclear matrices, hyaloplasm, and peroxisomal matrices of EPC-cells. It is suggested that an impairment of peroxisome formation is involved in the altered intracellular distribution of catalase. Administration of clofibrate increased the catalase activity in EPC-cells. To examine the preneoplastic nature of EPC-cells, activities of glucose-6-phosphatase (G6Pase) and gamma-glutamyl transpeptidase (GGT) were examined, since changes in the activities of these enzymes have been used as markers of putative preneoplastic cells. In the present study, neither weak G6Pase activity nor positive GGT activity was considered to be a consistent feature of EPC-cells. However, available evidence suggests that EPC-cells are one of the carcinogen-induced cell populations with altered phenotypes.

Animals↗
PubMed1981

Estimation of resistance to dimethylnitrosamine of normal hepatocytes, hyperplastic nodule cells and hepatoma cells of rats in primary culture.

Normal hepatocytes, hyperplastic nodule cells and hepatoma cells of rats induced by 2-acetylaminofluorene treatment were transferred to primary culture. After exposure of the cells to dimethylnitrosamine (DMN) at concentrations of 10(-2) M, 10(-3) M, and 10(-4) M for 48 hr, the attached cells which remained on the dishes in a flattened shape were counted. Resistance to DMN was expressed as the percentage of the attached cells relative to the control without DMN treatment. The percentages increased in the order of normal hepatocytes, hyperplastic nodule cells and hepatoma cells.

Animals↗