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Biomedical subjects

S Okada

Publications and source records attributed to S Okada.

At least 19 recordsLinked to original sources
PubMed1992

Changes of DNA methylation in protooncogenes in the process of radiation-induced transformation of mouse m5S/1M cells in vitro.

To assess the importance of changes in DNA methylation in an X-ray-induced cellular transformation process, methylation patterns of five nuclear protooncogenes in fifteen transformant clones were studied and compared to that of the parental non-transformed cell line m5S/1M. All transformants examined revealed an alteration in DNA methylation in some of the genes, although these changes were variable among them. A comparison of cellular characteristics with corresponding DNA methylation changes in different clones suggested that the loss of contact inhibition and the gain of anchorage independency were associated with increases of methylation in many genes, whereas the acquisition of tumorigenicity was often accompanied by a decrease of methylation in the N-myc and c-myc genes. Resultant data indicate that the alteration of DNA methylation is closely related to transformation process, yet how this involvement occurs is complex and remains unclear.

Animals↗
PubMed1992

Elevation of hepatic levels of metallothionein and zinc in mice bearing experimental tumors.

A tumor growth-dependent elevation in the hepatic levels of Zn and metallothionein (MT), without a change in the level of Cu, was found in mice and rats bearing solid tumors in the inguinal region. The levels of Zn and MT thus elevated gave a significant correlation (r = 0.95) between them. Nevertheless, when tumor-bearing mice and rats were fed a Zn-deficient diet, the hepatic levels of Zn and MT did not increase. In mice in which inflammation was induced at the same region, on the other hand, hepatic levels of Zn and MT increased transiently after the injection of turpentine or carrageenan even when they were fed the Zn-deficient diet. These results suggest that the elevation of MT and Zn levels can be a helpful marker for detecting malignancy.

Animals↗
PubMed1992

Structure of serum transferrin in carbohydrate-deficient glycoprotein syndrome.

The structure of the defective transferrin in carbohydrate-deficient glycoprotein syndrome was characterized. Structurally abnormal sugar chains were not found in reversed phase chromatograms of pyridylaminated derivatives from the transferrin of two patients in different families. Electrospray ionization mass spectrometry of the whole transferrin molecules revealed an abnormal species that was smaller than normal tetrasialotransferrin by 2,200 daltons, just the size of the disialylated biantennary sugar chain. These data indicated that the disialotransferrin specifically found in this syndrome is missing either of two N-linked sugar chains, suggesting a metabolic error in the early steps of protein glycosylation.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1992

In vivo and in vitro stem cell function of c-kit- and Sca-1-positive murine hematopoietic cells.

c-kit is expressed on hematopoietic stem cells and progenitor cells, but not on lymphohematopoietic differentiated cells. Lineage marker-negative, c-kit-positive (Lin-c-kit+) bone marrow cells were fractionated by means of Ly6A/E or Sca-1 expression. Lin-c-kit+Sca-1+ cells, which consisted of 0.08% of bone marrow nucleated cells, did not contain day-8 colony-forming units-spleen (CFU-S), but 80% were day-12 CFU-S. One hundred cells rescued the lethally irradiated mice and reconstituted hematopoiesis. On the other hand, 2 x 10(3) of Lin-c-kit+Sca-1- cells formed 20 day-8 and 11 day-12 spleen colonies, but they could not rescue the lethally irradiated mice. These data indicate that Lin-c-kit+Sca-1+ cells are primitive hematopoietic stem cells and that Sca-1-cells do not contain stem cells that reconstitute hematopoiesis. Lin-c-kit+Sca-1+ cells formed no colonies in the presence of stem cell factor (SCF) or interleukin-6 (IL-6), and only 10% of them formed colonies in the presence of IL-3. However, approximately 50% of them formed large colonies in the presence of IL-3, IL-6, and SCF. Moreover, when single cells were deposited into culture medium by fluorescence-activated cell sorter clone sorting system, 40% of them proliferated on a stromal cell line (PA-6) and proliferated for more than 2 weeks. In contrast, 15% of the Lin-c-kit+Sca-1-cells formed colonies in the presence of IL-3, but no synergistic effects were observed in combination with SCF plus IL-6 and/or IL-3. Approximately 10% proliferated on PA-6, but most of them degenerated within 2 weeks. The population ratio of c-kit+Sca-1+ to c-kit+Sca-1- increased 2 and 4 days after exposure to 5-fluorouracil (5-FU). These results are consistent with the relative enrichment of highly proliferative colony-forming cells by 5-FU. These data show that, although c-kit is found both on the primitive hematopoietic stem cells and progenitors, Sca-1+ cells are more primitive and respond better than Sca-1- cells to a combination of hematopoietic factors, including SCF and stromal cells.

Animals↗
PubMed1992

Action of neopullulanase. Neopullulanase catalyzes both hydrolysis and transglycosylation at alpha-(1----4)- and alpha-(1----6)-glucosidic linkages.

The transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1----4)-glucosidic linkages, but others were suggested to have alpha-(1----6)-glucosidic linkages. The existence of alpha-(1----6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1----4)- and alpha-(1----6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1----4)-glucosidic linkage, hydrolysis of alpha-(1----6)-glucosidic linkage, transglycosylation to form alpha-(1----4)-glucosidic linkage, and transglycosylation to form alpha-(1----6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1992

Report of a patient with POEMS/Takatsuki/Crow-Fukase syndrome associated with focal spinal pachymeningeal amyloidosis.

The authors present the results of an autopsy of a 67-year-old Japanese man with POEMS/Takatsuki/Crow-Fukase syndrome (P/T/CFS) diagnosed in 1972. Each component of the syndrome was gradually recognized after the resection of lumbar vertebral solitary plasmacytoma in 1967. The patient died in 1989 of generalized infection and renal failure. Autopsy revealed in the vertebral canal between the fifth and seventh thoracic vertebrae dorsal pachymeningeal fibrosis, with prominent amyloid deposition that oppressed the spinal cord. This condition was consistent with the final neurologic manifestation of the patient, bilateral motor and sensory disturbance below the sixth thoracic level. Myelopathy remained clinically unnoticed because neurologic disturbance had begun as peripheral polyneuropathy. Normocellular marrow with heterogeneously scattered lambda light chain-positive plasma cells and degeneration of the myelinated fibers of sciatic nerve also were observed. This is the first report of focal spinal amyloidosis associated with P/T/CFS.

Adult↗
PubMed1992

Tumor accumulation of novel RES-avoiding liposomes.

For passive targeting of liposomes to tumor tissues, we earlier developed reticuloendothelial system (RES)-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA) (Namba, Y., Sakakibara, T., Masada, M., Ito, F. and Oku, N. (1990) Chem. Pharm. Bull. 38, 1663-1666). In this present study, we examined the blood clearance and biodistribution of PGlcUA-liposomes (dipalmitoylphosphatidylcholine/cholesterol/PGlcUA = 40:40:20 as a molar ratio) in normal and tumor-bearing mice. Liposomes containing dipalmitoylphosphatidylglycerol (DPPG) instead of PGlcUA was also examined as a control. When [3H]inulin-encapsulated PGlcUA-liposomes and DPPG-liposomes were intravenously injected into normal mice, approx. 50% of the 3H radioactivity was recovered from the liver, the bulk of RES, at 12 h after administration of DPPG-liposomes, while only approx. 20% of it was found there when PGlcUA-liposomes were administered. Radioactivity remaining in the plasma at 12 h after injection was 5-fold higher when PGlcUA-liposomes were injected than when DPPG-liposomes were used. Biodistribution of liposomes in tumor-bearing mice was also examined. Mice were inoculated with 10(7) S180 cells into the hind leg. After 1 week, liposomes were injected. Radioactivity of [3H]inulin originally encapsulated in the PGlcUA-liposomes accumulated in the tumor to an extent 3-4-fold higher than that of the marker in DPPG-liposomes. Liver/tumor ratio of the radioactivity was 12 for DPPG-liposomes and only 2 for PGlcUA-liposomes. This latter value is the lowest of various liposome formulations ever reported.

Animals↗
PubMed1992

Effects of alkyl glycosides incorporated into liposomes prepared from synthetic amphiphiles on their tissue distribution in Ehrlich solid tumor-bearing mice.

A study of the effects of alkyl glycosides incorporated into synthetic liposomes with respect to their stability, their in vivo distribution in Ehrlich solid tumor-bearing mice and their in vitro interaction with liver cells was undertaken. The synthetic liposomes were prepared from N,N-didodecyl-N alpha-[6-(trimethylammonio)hexanoyl]-L-alaninamide bromide (N+C5Ala2C12) and labeled with 99mTc. n-Dodecyl glucoside (DG) and n-dodecyl sucrose (DS) were used as alkyl glycosides. The stability was hardly changed by incorporation of alkyl glycosides into the liposomes in saline and serum. The uptake of DG- and DS-modified N+C5Ala2C12 liposomes decreased in liver and spleen compared with that of unmodified N+C5Ala2C12 liposomes, resulting in an increase in blood and other tissues such as tumor, duodenum and kidney, where the DS-modified N+C5Ala2C12 liposomes had a marked tendency. It was observed with electron micrographs that the size of N+C5Ala2C12 liposomes became small by incorporation of alkyl glycoside. The smaller N+C5Ala2C12 liposomes were found to result in the lower uptake in liver. The interaction of the liposomes with liver cells in vitro indicated that both DG- and DS-modified liposomes had a low affinity for liver cells compared with the unmodified liposomes and the extent of interaction of the DS-modified liposomes was weaker than that of the DG-modified liposomes.

Alkylation↗
PubMed1992

Nucleotide sequence of the genome of the bacteriophage alpha 3: interrelationship of the genome structure and the gene products with those of the phages, phi X174, G4 and phi K.

The complete nucleotide sequence of the genome of the circular single-stranded DNA (isometric) phage alpha 3 has been determined and compared with that of the related phages phi X174 and G4. The alpha 3 genome consists of 6087 nucleotides, which is 701 nucleotides longer than the nucleotide sequence of the phi X174 genome and 510 nucleotides more than that of the G4 genome. The results demonstrated that the three phage species have 11 homologous genes (A, A*, B, C, K, D, E, J, F, G and H), the order of which is fundamentally identical, suggesting that they have evolved from a common ancestor. The sequence of some genes and untranslated intergenic regions, however, differs significantly from phage to phage: for example, the degree of amino acid sequence homology of the gene product is averaged at 47.7% between alpha 3 and phi X174 and 46.9% between alpha 3 and G4, and alpha 3 has a remarkable longer intergenic region composed of 758 nucleotides between the genes H and A compared with the counterparts of phi X174 and G4. Meanwhile, in vivo experiments of genetic complementation showed that alpha 3 can use none of the gene products of phi X174 and G4, whereas the related phage phi K can rescue alpha 3 nonsense mutants of the genes B, C, D and J. These sequencing and in vivo rescue results indicated that alpha 3 is closely related to phi K, but distantly remote from phi X174 or G4, and supported an evolutional hypothesis which has been so far proposed that the isometric phages are classified into three main groups: the generic representatives are phi X174, G4 and alpha 3.

Amino Acid Sequence↗
PubMed1992

GM1 gangliosidosis in adults: clinical and molecular analysis of 16 Japanese patients.

Clinical findings were compared with the results of molecular analysis in 16 Japanese patients from 10 unrelated families with the adult/chronic form of GM1 gangliosidosis. Age of onset ranged from 3 to 30 years. Major clinical manifestations were gait and speech disturbances caused by persistent muscle hypertonia. Dystonic postures and movements, facial grimacing, and parkinsonian manifestations were commonly seen. Cerebellar signs, myoclonus, severe intellectual impairment, dysmorphism, or visceromegaly were not observed. A common single-base substitution, 51Ile(ATC)----Thr(ACC), reported in a previous study of ours, was confirmed in 14 patients by the Bsu36I restriction site analysis; one was a compound heterozygote with another mutation (457Arg[CGA]----Gln[CAA]) and the others were homozygotes of this mutation. Clinically, the compound-heterozygous patient showed more severe neurological manifestations and a more rapid clinical course than those of homozygotes. The homozygotes showed considerable variations in the age of onset and subsequent clinical course. The 51Ile----Thr mutant allele expressed a significant amount of beta-galactosidase activity, whereas the 457Arg----Gln mutant allele expressed extremely low activity in human GM1 gangliosidosis fibroblasts. We conclude that these gene mutations causing different residual enzyme activities are related to the severity of clinical manifestations, but some other genetic or environmental factors contribute to clinical heterogeneity. The Bsu36I restriction site analysis was performed in 7 families and provided clear results for the diagnosis of heterozygotes as well as homozygotes of this specific clinical form of GM1 gangliosidosis. The technique is applicable to prenatal diagnosis and genetic counseling.

Adult↗
PubMed1992

Prognostic factors in patients with hepatocellular carcinoma receiving systemic chemotherapy.

A total of 71 consecutive patients with unresectable hepatocellular carcinoma were analyzed retrospectively to determine the significant prognostic factors. All the patients received systemic chemotherapy in a phase 2 study from 1980 to 1990, with no other anticancer treatment. Median survival time and 1-yr and 2-yr survival rates were 5.6 mo, 23% and 5%, respectively. By the univariate analysis, a performance status of 0-1 and tumor size less than 50% of the liver cross-sectional area were shown to be the factors most significantly favoring a better prognosis. By the multivariate analysis using the Cox proportional hazards model, a performance status of 0-1 (p less than 0.001), absence of tumor thrombus in the main portal trunk (p = 0.003) and age less than 60 yr (p = 0.036) were independent favorable prognostic factors. A prognostic index was calculated from these three factors according to the following equation: 1.8109 x (0 = performance status of 0-1 and 1 = performance status of 2-3) + 0.9322 x (0 = tumor thrombus absent in the main portal trunk and 1 = present) + 0.6996 x (0 = age less than 60 yr and 1 = age greater than or equal to 60 yr). This index was used to classify the patients into three groups with a good, intermediate and poor prognosis. The median survival times for these three groups were 9.8, 3.8 and 1.9 mo, respectively (p less than 0.01). The results of this study may be useful in the design and analysis of future clinical trials of systemic therapy for hepatocellular carcinoma.

Analysis of Variance↗
PubMed1992

The degree of variability in the amino terminal region of the E2/NS1 protein of hepatitis C virus correlates with responsiveness to interferon therapy in viremic patients.

We investigated amino acid heterogeneity in the variable regions of the E2/NS1 viral protein in interferon-responsive and interferon-nonresponsive patients with chronic hepatitis C virus infection. The study assessed whether any particular heterogeneity pattern(s) could be useful in predicting responsiveness to interferon treatment. The nucleic acid sequences of the hepatitis C virus genome were analyzed from six patients with chronic hepatitis treated with an interferon-beta, three of whom did not respond to the therapy and another three who showed remarkable improvement in the serum levels of liver enzymes and hepatitis C virus RNA after 6 mo. The complementary DNA clones propagated from each of the nonresponders showed significant diversity of both nucleotide and amino acid sequence, especially at the hypervariable region 1 within the putative E2/NS1 gene of the virus, suggesting that these patients were infected with a large heterogeneous pool of hepatitis C virus variants. In contrast, the responders showed little or no diversity in the sequence of the complementary DNA clones, suggesting that they were infected with one or a small population of viral genotypes containing significantly less variability in the E2/NS1 hypervariable region 1. These results suggested that a large variable population of hepatitis C virus genotypes is implicated in patients who are nonresponders to interferon treatment. In addition, a significant change in the hepatitis C virus genotype population was observed in nonresponders after interferon treatment. This may reflect a differential viral sensitivity to interferon, selective immune pressure by the host or both.

Adult↗
PubMed1992

Postresection recurrence of hepatocellular carcinoma treated by arterial embolization: analysis of prognostic factors.

Of 270 consecutive patients with hepatocellular carcinoma who underwent surgery, 50 who had recurrence and were subsequently treated with transcatheter arterial embolization were analyzed. The longest interval between surgery and recurrence in the 50 patients who underwent transcatheter arterial embolization was 7 yr. Recurrence was initially found in the remnant liver in all patients but one; extrahepatic metastases were detected in 13 patients (26%) during follow-up. A "multiple" type was the most common (64%) hepatic recurrence pattern on angiography, followed by the "solitary" (16%) and "tumor thrombus" (12%) patterns. Hepatic recurrence was most frequently found in the ipsilateral lobe (48%) relative to the site of the primary hepatocellular carcinoma. Multivariate analysis of the factors affecting survival after transcatheter arterial embolization indicated that recurrence pattern (p = 0.025) and distant metastases (p = 0.011) were significant. Of 13 patients with distant metastases, 11 had the "multiple" pattern of hepatic recurrence. Survival rates for all 50 patients after initial surgery and after transcatheter arterial embolization were 90% and 64%, respectively, at 1 yr; 52% and 24%, respectively, at 3 yr; and 27% and 5%, respectively, at 5 yr. On analysis of survival rates after transcatheter arterial embolization in 37 patients with recurrence only in the liver and of the response of recurrent hepatocellular carcinoma to transcatheter arterial embolization, a significant difference was noted between those with "partial response" and "progressive disease" (p less than 0.05) and between those with "no change" and "progressive disease" (p less than 0.05).

Adult↗
PubMed1992

A case of pigmentary type of orthochromatic leukodystrophy with early onset and globoid cells.

We report herein a sporadic case of the pigmentary type of orthochromatic leukodystrophy with early onset and very rapid clinical course. The patient's development was normal until 2 years old, when he experienced visual disturbance. Rapid deterioration resulted in death 1.5 years after the onset. Metachromatic leukodystrophy, globoid cell leukodystrophy and adrenoleukodystrophy were excluded by biochemical assays. Autopsy findings were compatible with the diagnosis of the pigmentary type of orthochromatic leukodystrophy. However, there were unique findings of severe neuronal loss and the collection of globoid-like cells in the interface of the gray matter and the white matter. Immunohistochemical staining of myelin basic protein, proteolipid protein and galactocerebroside demonstrated that these myelin constituents were equally preserved in the posterior column, while absent in the lateral and anterior columns of the spinal cord.

Autopsy↗
PubMed1992

Inverse dose-rate effect of DNA breaks and inactivation of transforming activity induced by tritiated water and 60Co gamma-rays.

When an aqueous solution of plasmid DNA at a constant low concentration of 5 micrograms/cm3 was irradiated with 60Co gamma-rays, D37 dose of single-strand breaks was decreased from 18 Gy at a dose-rate of 6.77 Gy/h of acute irradiation to 2.3 Gy at a dose-rate of 0.00212 Gy/h. Or G value was increased from 0.0010 to 0.0081. Similar dose-rate dependency of D37 dose and G value were also found when the plasmid DNA solution was treated with various concentrations of tritiated water at various dose-rates, ranging from 5.13 Gy/h to 0.000118 Gy/h. RBE of tritium beta-rays for single-strand breaks was ranged from 0.3 to 0.5 in a wide range of dose-rates. When the DNA solution was saturated with argon to remove oxygen, the dose-rate dependency of gamma-rays was abolished and that of tritium beta-rays was significantly suppressed. When the DNA solution in air was kept at 4 degrees C for 50 h or 25 days after acute irradiation, the G value of DNA breaks was the same as that kept at -20 degrees C for the same period, but much lower than that of the solution irradiated for the same period at a lower dose-rate to give the same total doses. This shows that the inverse dose-rate effect could not be induced from the different exposure periods but from continuous irradiation of different dose-rates. The inverse dose-rate effect for inactivation of transforming activity of DNA irradiated with tritiated water was also observed in the range from 0.0588 Gy/h to 0.00118 Gy/h.

Cobalt Radioisotopes↗
PubMed1992

Liposomal modification with uronate, which endows liposomes with long circulation in vivo, reduces the uptake of liposomes by J774 cells in vitro.

For overcoming rapid removal of liposomes from the bloodstream, we developed reticuloendothelial system (RES)-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA). In this current study, we examined the in vitro interaction of PGlcUA-liposomes with J774 cells derived from mouse macrophages. Liposomal association with J774 cells at 37 degrees C did not increase compared with the binding at 4 degrees C when liposomes were modified with PGlcUA. RES-avoiding ability was not specifically endowed by glucuronate but by uronates in general, since palmityl-D-galacturonide showed a similar effect on liposomal clearance in vivo and liposomal uptake in vitro. These facts indicate that modification of the liposomal surface with uronic acid derivatives endows liposomes with a long circulation time in the bloodstream by reducing their uptake by macrophages.

Animals↗
PubMed1992

Induction of external abnormalities in offspring of male mice irradiated with 252Cf neutron.

To assess the genetic effects of fission neutron, the induction of external malformations was studied in F1 fetuses after F0 male mice were irradiated. Male mice of the ICR:MCH strain were irradiated with 252Cf neutron at doses of 0.238, 0.475, 0.95 and 1.9 Gy. They were mated with non-irradiated female mice at 71-120 days after the irradiation. Pregnant females were autopsied on day 18 of gestation and their fetuses were examined for deaths and external abnormalities. No increases of pre- and post-implantation losses were noted at any dose. External abnormalities were observed at rates of 1.40% in the 0.238 Gy, 2.23% in the 0.475 Gy, 3.36% in the 0.95 Gy and 3.26% in the 1.9 Gy groups; the rate in the control group was 1.65%. The dose-response curve was linear up to 0.95 Gy, and then flattened out; the induction rate of external abnormalities was 2.7 x 10(-4)/gamete/cGy based on the linear regression. These results indicated that fission neutron effectively induces external abnormalities in F1 fetuses after spermatogonial irradiation.

Abnormalities, Radiation-Induced↗