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Biomedical subjects

K Okabayashi

Publications and source records attributed to K Okabayashi.

At least 91 records · Page 5Linked to original sources
PubMed1991

Secretory expression of the human serum albumin gene in the yeast, Saccharomyces cerevisiae.

We have fused a cDNA gene encoding mature human serum albumin (HSA) to several secretory leader-encoding sequences. The hybrid genes were cloned into an episomal vector under the control of several yeast promoters and then introduced into yeast cells. The GAL1 promoter in combination with either the native HSA pre-sequence or a modified HSA pre-sequence gave the highest production of immunoreactive HSA, 90 mg/liter being reached in a shake flask culture. The invertase pre-sequence, the mating factor alpha 1 prepro-sequence, and the modified HSA pre-sequence directed accurate processing. In contrast, the chicken lysozyme pre-sequence and the native HSA pre-sequence directed incorrect processing. Episomal vectors were unstable within the host cells under non-selective culture conditions. To improve the plasmid stability, the hybrid genes were incorporated into an integrative vector. Transformants carrying multicopies of the plasmid integrated at the LEU2 locus stably secreted HSA. The highest yield of 65 mg/liter in a shake flask culture was obtained with the combination of the yeast glyceraldehyde-3-phosphate dehydrogenase promoter and the modified HSA pre-sequence. By constructing transformed strains containing multicopies of plasmids integrated at both the chromosome LEU2 and HIS4 loci, we have obtained a stable strain that continuously secretes as much as 85 mg HSA per liter of culture medium.

Amino Acid Sequence↗
PubMed1990

Structural changes of Kupffer cells in rat liver following experimental thermal injury.

Changes in plasma haemoglobin levels and morphology of Kupffer cells were studied in rats following lethal thermal injury. Severe haemolysis was observed immediately after thermal injury. The plasma haemoglobin levels rapidly increased to a maximum level 15 min after injury and then rapidly decreased with time. However, the values were still higher 5 h after injury than those found before injury. Soon after burning the Kupffer cells phagocytized not only circulating cell debris including erythrocyte membranes and degenerate leucocytes but also large amounts of haemoglobin. The degradation of phagocytized haemoglobin was relatively slow compared to that of other cell debris. This phagocytized haemoglobin is considered to inhibit the generation of bactericidal-free radicals and to depress Kupffer cell function. The number of Kupffer cells was markedly decreased 5 h after thermal injury, and probably relates to the persistent depletion of the reticuloendothelial system function which follows lethal thermal injury. In contrast to the decreased number of Kupffer cells, a small number of monocytic cells appeared in the sinusoidal spaces and adhered to the endothelial cells. These monocytic cells may transform into Kupffer cells.

Animals↗
PubMed1990

[Biochemical analysis of bone and mineral metabolism in liver cirrhosis].

We investigated the disorder of bone and mineral metabolism in 29 patients with liver cirrhosis who were classified into two subgroups with (group 1, n = 13) or without (group 2, n = 13) osteopenia according to the method of Jikei. Serum levels of osteocalcin level, bone-type alkaline phosphatase activity and calcium concentration in serum and urine in these patients and 25 normal control subjects were determined. Serum osteocalcin level and bone-type alkaline phosphatase activity were elevated in group 1 compared with those in group 2 and normal control subjects. Serum and urine calcium levels in group 1 were similar to those in group 2. However calcium-creatinine ratio in urine was higher in group 1 than in group 2. These present observations indicate that osteopenia in patients with liver cirrhosis is due to high turnover of bone metabolism.

Adult↗
PubMed1989

Computer analysis in making preoperative decisions: a rational approach to lymph node dissection in gastric cancer patients.

In Japan, R2 lymph node dissection is standard practice for all curatively resected gastric cancer patients. From 1969 to 1984, data were collected prospectively to evaluate this procedure and to provide information for a more rational approach to node dissection for each individual case. A total of 3843 cases was included in this study and an evaluation was made of the prognostic variables and lymph node involvement at various locations. Using a computer program, it is possible to compile a group of treated patients, with prognostic variables exactly matching those of an individual patient. Analysis of this group can then give an indication of the extent of lymph node dissection required for an individual patient. This paper gives a demonstration of the structure of such a system by means of an example.

Decision Making, Computer-Assisted↗
PubMed1989

Lymph node metastases of gastric cancer. General pattern in 1931 patients.

The incidence of metastases from gastric adenocarcinoma to various regional lymph node stations was studied after meticulous node dissection and correlated to survival in 1931 resected patients. The incidence of metastases increased with deeper tumor invasion into the stomach wall. Deposits were most common in some perigastric node stations, and their distribution was clearly related to the location of the tumor. Some nonperigastric node stations also were frequently involved, e.g., those around the left gastric artery or in the splenic hilum, and may be considered primary draining nodes. Skip metastases to distant nodes were found in a few per cent of perigastric node-negative patients. Deposits in nodes around the middle colic artery, but not in any other upper abdominal node stations, were incompatible with 5-year survival rates. The analysis favors a so-called R2 or more extensive resection for cancers invading beyond the submucosa.

Female↗
PubMed1989

Effect of butyrate on the expression of the human preprourokinase gene introduced into Chinese hamster ovary cells.

A plasmid containing the human preprourokinase gene cDNA under the control of the simian virus 40 early region promoter was introduced into CHO-K1 cells and recombinant cell lines secreting a relatively high level of urokinase were obtained. In the course of studying the effects of various agents on the recombinant cell lines, we found that exposure of recombinant cells to 5 mM butyrate for 24 hours resulted in a 2-3 fold increase in urokinase production. The induction by butyrate was dose-dependent. The half maximal dose was approximately 2 mM; maximal stimulation occurred at 5-10 mM. Cell growth, on the other hand, was inhibited by butyrate concentrations greater than 2.5 mM. The response of cells to butyrate was rapid: a significant increase in urokinase production was observed 6 hours after exposure to 5 mM butyrate. Butyrate treatment increased not only the extracellular level but also the intracellular level of urokinase.

Animals↗
PubMed1989

[Reasonable lymph node dissection in radical gastrectomy for gastric cancer: introduction of computer information system and lymphography technique by India-ink].

A computer information system was developed and clinically used in National Cancer Center Tokyo in 1983. Seven data of an individual patient are preoperatively input in the system: sex, age, location, macroscopic type, maximal diameter, depth of invasion, and histological type of biopsy. After the data-analysis of 3,785 patients, the computer outputs three data; expected five year survival rate, each metastatic rate of 16 regional lymph nodes, and types of recurrence. Plan of lymph node dissection can reasonably be decided by this report. 0.5ml of India-ink (CH-40) is injected in the perigastric lymph nodes, and it stains all lymphatic channels from the injection points in black. Using the technique, systematic dissection can be performed easily and completely. After the introduction of these systems, five year survival rate was improved from 90.0% to 95.5% in Stage I, from 76.0% to 81.6% in Stage II, from 51.1% to 56.8% in Stage III, and from 12.9% to 16.6% in Stage IV.

Carbon↗
PubMed1988

Close correlation between restriction fragment length polymorphism of the L-MYC gene and metastasis of human lung cancer to the lymph nodes and other organs.

Restriction length fragment polymorphism of the L-MYC gene was examined in DNAs from lung cancer tissues and normal tissues of 51 Japanese patients with lung cancer. In individual patients, no difference was seen between the restriction length fragments of the two alleles of L-MYC [6-kilobase (kb) and 10-kb fragments in EcoRI digests] in lung cancer tissues and normal tissues. But a striking correlation was found between the restriction length fragment polymorphism pattern of L-MYC and the extent of metastasis, particularly to the lymph nodes at the time of surgery: Patients with only the L band (10 kb) had few lymph node metastatic lesions, whereas patients with either the S band (6 kb) or the S and L bands almost always had lymph node metastatic lesion. A similar correlation was found between the presence of the S band and metastases to other organs. This correlation was particularly marked in cases of adenocarcinoma. These results indicate a clear genetic influence on metastases and a consequent poor prognosis for certain patients of lung cancer; L-MYC restriction length fragment polymorphism is thus shown to be a useful marker for predicting the metastatic potential of human lung cancer.

Adult↗
PubMed1988

Behavior of human apolipoprotein A-I: phospholipid and apoHDL:phospholipid complexes in vitro and after injection into rabbits.

Apolipoprotein A-I was purified from human high density lipoprotein and complexed with polyunsaturated phosphatidylcholine (PC) in deoxycholate (Lipostabil); the bile salt was removed subsequently by dialysis. The behavior of the resultant apoA-I/PC complexes was compared with that of Lipostabil in vitro and after injection into rabbits. In vivo apoA-I/PC complexes had the density of HDL throughout but had both alpha and pre beta electrophoretic mobility, the latter probably reflecting dissociation of apoA-I from PC. Lipostabil initially behaved like LDL but gradually acquired the density of HDL after incubation with plasma and in vivo. Both preparations increased plasma total phospholipids in normolipidemic rabbits to a similar extent, but, increments in HDL phospholipid were greater after apoA-I/PC complexes were injected. ApoHDL/PC complexes, prepared in a similar manner, appeared to promote efflux of cholesterol from perfused rabbit aortas in the presence of lecithin:cholesterol acyltransferase (LCAT) activity, consistent with a stimulatory effect on cholesterol mobilization. Injection of apoHDL/PC complexes into hyperlipidemic rabbits decreased plasma cholesterol but increased HDL cholesterol, whereas Lipostabil decreased both. These findings suggest that human apoA-I/PC complexes resemble HDL in their behavior more closely than does Lipostabil, and show that both types of liposome undergo modification upon interaction with plasma. It remains to be shown whether they possess any therapeutic potential.

Animals↗
PubMed1986

[Immunohistochemical study of oncogene-related products in human gastrointestinal malignancies--expression of ras p 21, fes p 85 and EGF receptor].

An immunohistochemical examination by the avidin-biotin-peroxidase complex method was carried out to assess the expression of oncogene-related products, i.e., ras p 21 protein, fes p 85 protein and epidermal-growth-factor (EGF) receptors, in human gastrointestinal malignancies. The presence of ras p 21, fes p 85 and EGF receptors was detected in 48%, 62%, and 62% of 29 colorectal carcinomas and in 65%, 65% and 40% of 20 gastric cancers, respectively. More than one oncogene protein was demonstrated in 18 of 29 colorectal carcinomas and in 10 of 20 gastric cancers. These results suggest that multiple oncogenes are important in the occurrence and progress of gastrointestinal malignancies.

Colonic Neoplasms↗
PubMed1984

Purification and properties of mitochondrial malate dehydrogenase from unfertilized eggs of the sea urchin, Anthocidaris crassispina.

Purification and characterization of mitochondrial malate dehydrogenase [EC 1.1.1.37] from unfertilized eggs of the sea urchin, Anthocidaris crassispina, are described. The purification method consisted of dextran sulfate fractionation, Blue Dextran Sepharose chromatography, Phenyl-Sepharose hydrophobic chromatography and DEAE-cellulose chromatography. The enzyme was purified 771-fold with a 7% yield from the crude extract. The purified enzyme appeared homogeneous on polyacrylamide gel electrophoresis under both native and denatured conditions. After incubation at 45 degrees C for 50 min, the enzyme lost about 90% of its activity. In the presence of NADH, however, the enzyme was protected against the heat denaturation. The native enzyme had a molecular weight of about 65,000 and probably consisted of two identical subunits. In the reduction of oxaloacetate with NADH, a broad optimum pH ranging from 8.2 to 9.4 was found with 50 mM Tris-HCl and glycine-NaOH buffers. Sodium phosphate buffer apparently activated the enzyme. The apparent Km values for oxaloacetate and NADH were 19 microM and 30 microM, respectively. The optimum pH for malate oxidation with NAD+ was 10.2 in 50 mM NaHCO3-Na2CO3 buffer. The apparent Km values for malate and NAD+ were 7.0 mM and 0.6 mM, respectively. Zinc ion, sulfite ion, p-chloromercuriphenylsulfonate and adenine nucleotides strongly inhibited the enzyme.

Animals↗
PubMed1984

Pneumocystis carinii: electron microscopic investigation on the interaction of trophozoite and alveolar lining cell.

The habitat, behaviour of Pneumocystis carinii, and the interaction between the organisms and host alveolar cells were studied electron microscopically in corticosteroid-treated rats. The trophozoites of P. carinii used to line up along the type I alveolar epithelial cells at the early stage of infection. No organism was found being adhere to type II cells which have numerous microvilli on their surface. By adding tannic acid to the fixative we could preserve the alveolar lining layer, in which the organisms were found all the time. Therefore P. carinii is not exposed to alveolar air but is living in the liquid layer. Those findings are important in considering nutrition of the organism as well as pathogenicity to the host. The trophozoites and type I cells were in close contact mostly with their smooth surface rather than with tubular expansions of the organism. The cytoplasm of type I cell was often found protruded along the pellicle of the organism as if it surrounded the organism. Phagocytosis of P. carinii by alveolar macrophage and neutrophil was often seen in the alveolar lumen when the infection advanced. Sometimes the trophozoites were found sub- and intra- epithelially . Those trophozoites seemed alive from their ultrastructures. However, it remained unsolved, whether those figures were the resultants of active invasion of the trophozoite or of being surrounded by the epithelial cells.

Animals↗
PubMed1983

The cytochrome system of sea urchin eggs and embryos.

The cytochrome system in eggs and embryos of the sea urchin, Hemicentrotus pulcherrimus, was investigated. Difference spectra of the mitochondrial fraction demonstrated the presence of a complete cytochrome system in unfertilized eggs. Cytochrome levels and the activities of respiratory enzymes were measured in crude extracts of eggs both before and after fertilization. Unfertilized eggs contained cytochromes aa3, b, and c + c1 in a ratio of 1.0:1.8:0.7. Gastrulae contained almost the same amount of cytochromes aa3 and b as unfertilized eggs. However, the amount of cytochrome c + c1 in gastrulae was 1.5 times greater than that in unfertilized eggs. The activity of cytochrome oxidase remained unchanged during development. No cytochrome oxidase inhibitor was found in unfertilized eggs. Both antimycin A-sensitive and insensitive NADH-cytochrome c reductase activities increased during development. The activity of succinate-cytochrome c reductase increased during early development, reached a temporary plateau, and then declined at the pluteus stage. These results are discussed in relation to the increase of respiration during early development.

Animals↗
PubMed1983

Report of an imported case of Dipetalonema perstans in Japan.

A case of Dipetalonema perstans infection in a 34-year-old Japanese male is presented and from his past history there is no doubt that he obtained the infection in Zaire, Africa. The morphology and periodicity of the microfilaria were studied in detail and the clinical manifestations of the infection documented. This is the first report of imported D. perstans infection in Japan.

Adult↗
PubMed1983

[Prognostic factors and surgical method in patients with leiomyosarcoma of the stomach--with special reference to local tumor excision].

Between 1962 and 1982, 48 patients with leiomyosarcoma of the stomach who had undergone resection at the National Cancer Center Hospital were studied to define the prognostic factors clinicopathologically and the criteria of local excision of the tumors. The 5 and 10-year survival rate after resection was 84.3% and 80.5% respectively. Since the extent of surgical resection did not affect survival, gastrectomy is of no greater benefit than local excision. The important prognostic factors were location, size, mitotic index and cellularity of the tumor. Criteria of local tumor excision are defined as tumor location in the anterior wall, small size (much less than 5.0 cm in diameter), low mitotic index (5.0/25 HPF) of low cellularity (0-3/0.0004 mm2).

Adult↗