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Biomedical subjects

M Usami

Publications and source records attributed to M Usami.

332 records · Page 19Linked to original sources
PubMedDate not supplied

The effect of a nucleotide-nucleoside solution on hepatic regeneration after partial hepatectomy in rats.

After hepatectomy, purine and pyrimidine metabolism is a key process in the synthesis of DNA and RNA and maintaining cellular energy metabolism. The purpose of this study is to evaluate changes in blood purine and pyrimidine levels after partial hepatectomy and the effect of purine and pyrimidine nucleoside solution injection on hepatic regeneration under the hypothesis that the rat after partial hepatectomy requires substrates for salvage nucleotide synthesis and changes blood nucleoside and nucleobase levels. Blood levels of nucleotides, nucleosides, and nucleobase by high-performance liquid chromatography method and liver ATP level by enzymatic analysis, and the effect of preoperative injection of nucleoside solution (OG-VI) on hepatic regeneration ratio and hepatocytes DNA synthesis, were assessed in rats after 70% partial hepatectomy. Decreased liver adenosine triphosphate and increased plasma xanthine and hypoxanthine after partial hepatectomy indicated an increase in catabolism of purine nucleotides in regenerating liver. Plasma thymidine and cytidine levels increased, then returned to the prevalue, suggesting that the thymidine and cytidine pool was enlarged. OG-VI increased labeling indices of hepatocytes at postoperative d 1 (POD) and hepatic regeneration ratio at POD 14. Blood purine nucleobase and pyrimidine nucleoside levels change after partial hepatectomy and preoperative supply of nucleoside solution is effective for increasing hepatocytes DNA synthesis and hepatic regeneration after partial hepatectomy.

Adenosine Triphosphate↗
PubMedDate not supplied

Therapeutic plasmapheresis for liver failure after hepatectomy.

Therapeutic plasmapheresis (PP) for liver failure following the resection of primary liver cancer was evaluated retrospectively. PP was repeated two to three times per week using plasma exchange (PE) with fresh frozen plasma as a substitution fluid in all eight cases and direct hemoperfusion (DHP) in two cases. PE effectively decreased serum bilirubin and/or improved hepatic encephalopathy in six of eight patients and prolonged survival time (p less than 0.05, chi-square test). DHP was not effective. Liver failure following the resection of damaged liver differs from acute liver failure in both the condition itself and the reaction to PP. Fractionation of serum bilirubin using high performance liquid chromatography showed differences in the ratio of delta bilirubin in one survivor versus two who died and was effective in selecting a patient who would respond to PE. In conclusion, PE is effective in prolonging survival time after liver failure in hepatectomized patients compared to conventional therapy.

Bilirubin↗
PubMedDate not supplied

Effects of nucleosides and a nucleotide on DNA and RNA syntheses by the salvage and de novo pathway in primary monolayer cultures of hepatocytes and hepatoma cells.

Studies were made on the effects of inosine, guanosine 5'-monophosphate (GMP), cytidine, uridine, thymidine, and their mixture (4:4:4:3:1, OG-VI) on DNA and RNA syntheses in primary monolayer cultures of normal hepatocytes and cultures of hepatoma cells, AH130, to use these compounds for total parenteral nutrition. Addition of an appropriate amount of inosine, GMP, uridine, or thymidine to primary cultures of hepatocytes enhanced both DNA and RNA syntheses by the salvage and de novo pathways. Cytidine appeared to have lower optimal concentration for enhancing these pathways. The OG-VI mixture also enhanced the syntheses of DNA and RNA, but the composition of the mixture was not optimal. Additions of inosine, GMP, uridine, and thymidine to cultured hepatoma cells also enhanced their DNA and RNA syntheses, but the cells consumed more of the added nucleic acid compounds than hepatocytes did. Addition of cytidine had no effect on proliferation of the cells. The OG-VI mixture at relatively higher concentration inhibited the syntheses of DNA and RNA by hepatoma cells. Addition of high concentrations of nucleic acid compounds was found to suppress the proliferation of both hepatocytes and hepatoma cells. These results suggest that addition of optimal amounts of nucleic acid compounds such as nucleosides and nucleotides would enhance growth of hepatocytes, particularly during liver regeneration, but that they may also enhance proliferation of tumor cells in the liver.

Animals↗
PubMedDate not supplied

Effect of methionine-deprived nutrition on cell growth and cell kinetics in cell cultures and experimental tumors.

The effect of methionine-deprived nutrition on cell growth and cell kinetics was investigated in cell cultures and in tumor-bearing rats using the total parenteral nutrition (TPN) technique. A simultaneous flow cytometric measurement of the cellular DNA content and the amount of 5-bromodeoxyuridine incorporated into cellular DNA was performed for analysis of cell kinetics. The methionine-free medium demonstrated a cytocidal effect on the growth of SLC cells after 6 hours of culturing. It decreased viability from 80% in the control medium to 23%, and it decreased the S phase and increased the G0/G1 phase of the cell cycles. The methionine-deprived medium showed a concentration-dependent inhibition in cellular growth. Methionine-deprived TPN was seen to inhibit AH109A and SLC tumor growth compared with conventional TPN and decreased the S phase and increased the G0/G1 phase of cell cycles. These results confirm that methionine deprivation blocks cells from processing into the G1 phase and recycling, and that it is effective in inhibiting tumor growth in cultures and in vivo.

Animals↗
PubMedDate not supplied

The age-related difference in bone changes in rats induced by recombinant human granulocyte colony-stimulating factor.

We examined the bone changes in recombinant granulocyte colon-stimulating factor (rhG-CSF)-treated young and young adult rats in order to investigate the effect of age-related conditions of bone growth on the bone changes induced by rhG-CSF. Recombinant human G-CSF (100 and 1,000 micrograms/kg/day) was given to rats by daily intravenous injection for 28 days starting at the age of either 6 or 14 wk, and the hindlimb bones were evaluated histopathologically. In the young rats, bone lesions were observed in the 100- and 1,000-micrograms/k groups. In the young adult rats, lesions were found only in the 1,000-micrograms/kg group. The lesions involved accelerated osteoclastic bone resorption and osteogenesis due to intramembranous ossification and there was no age-related difference in these histopathological findings. However, both the incidence of bone involvement and the severity of lesions were greater in the young rats than in the dose-matched young adult rats. The results suggest that the higher dose of rhG-CSF may intrinsically induce bone lesions of a particular histopathological nature in rats regardless of their age, and the action of rhG-CSF on bone may be stronger in young growing rats than in young adults.

Age Factors↗
PubMedDate not supplied

CA125-positive papillary tumor of the peritoneum.

A 71-year-old female visited our outpatient unit with chief complaints of anorexia and a sense of abdominal distension. The abnormalities found after admission were conspicious increases in CA125 levels in serum and ascites as well as anemia, accelerated erythrocyte sedimentation and increased serum LDH. The patient underwent an emergency operation for ileus. The histological diagnosis was serous papillomatous cancer. Immunohistologic staining of the cancer tissue demonstrated the production of CA125. In this very rare the remnant of the Müllerian duct in the peritoneum is thought to have been cancerous.

Aged↗