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Biomedical subjects

T Oka

Publications and source records attributed to T Oka.

At least 703 records · Page 39Linked to original sources
PubMed1992

An efficient expression system for a variant form of the cytotoxic protein alpha-sarcin in Escherichia coli.

An efficient Escherichia coli system for the production of a variant form of the cytotoxic protein alpha-sarcin (delta Ala 1) has been constructed. cDNA encoded alpha-sarcin lacking N-terminal alanine was ligated with the bla signal peptide sequence (the signal sequence of E. coli beta-lactamase localizes the protein in the periplasm) and was inserted into an inducible bacterial expression vector pKTN2-2. When the plasmid introduced into E. coli was expressed in the presence of IPTG, the recombinant product accumulated in the periplasmic space. The product was purified by Affi-Gel Blue followed by Bio-Rex 70 column chromatography. Recombinant alpha-sarcin (delta Ala 1) displayed the properties similar to those of authentic alpha-sarcin isolated from Aspergillus giganteus with respect to its molecular mass and enzymatic activity in ribosomal inactivation. The amount of alpha-sarcin variant produced in the system was estimated to be 1.2 mg/l of culture.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of chick liver HMG 2a cDNA and developmental expression of HMG 2a mRNA.

The cDNA clone encoding HMG 2a of chick liver was isolated from a lambda gt11 expression library using polyclonal antibodies. DNA sequence analysis revealed an open reading frame of 201 amino acids. Comparison of the nucleotide sequences of cDNA coding for chick liver HMG 2a with pig thymus HMG 2 and human monocytic leukemia cell HMG 2 showed 70% homology. 2.0 kb and 1.2 kb mRNAs were found in newly hatched chick liver and decreased during postnatal development of chicks.

Amino Acid Sequence↗
PubMed1992

Developmental changes in intestinal glucose transporter mRNA levels.

Developmental changes in glucose transporter mRNA levels in the jejunum of rats of different ages were examined by using slot blot RNA analysis. The level of SGLT1 mRNA did not change significantly through life. The GLUT5 mRNA level was highest in 10-day-old rats and then decreased reaching the adult level by day 20 after birth. The GLUT2 mRNA level was low in rats of 5 and 10 days old, but then increased progressively reaching the adult value by day 25 after birth. These results indicate that the expressions of intestinal facilitative glucose transporter genes change markedly in the third week after birth.

Aging↗
PubMed1992

The presence of free D-serine in rat brain.

Free amino acid enantiomers in adult rat brain extracts were analyzed as their N,O-pentafluoropropionyl isopropyl derivatives by gas chromatography on a capillary column of Chirasil-L-Val. A peak X, which exhibited the same retention time as the N,O-pentafluoropropionyl isopropyl derivative of authentic D-serine, was detected in the brain extracts. Electron impact and positive chemical ionization mass spectra of the peak X of the brain extracts were identical to those of authentic D-serine. The concentration of free D-serine and the ratio of D-serine/total serine in the brain were estimated to be 0.27 and 0.23 mumol/g of wet weight, respectively. These data provide the first evidence that substantial quantities of free D-serine are present in mammalian brain tissues.

Animals↗
PubMed1992

Differential mechanisms of induction of ornithine decarboxylase in rat intestine by L- and D-amino acids.

A single intragastric administration of glycine, L- and D-alanine, and L-and D-serine into rats resulted in a more than 20-fold stimulation of intestinal mucosal ornithine decarboxylase (ODC) within 4 h. The stimulation of ODC activity was accompanied by an increase in the amount of immunoreactive ODC protein. The induction of ODC by D-amino acids was in all likelihood attributable to an enhanced accumulation of ODC-specific mRNA species as revealed by Northern blot and dot-blot hybridization analyses. However, the induction by glycine and L-amino acids was not explainable by changes of mRNA since the changes in mRNA contents were only marginal. Since the turnover rates of L-serine-induced and D-serine-induced intestinal ODC protein were the same as the non-induced control, we concluded that the induction by glycine and L-amino acids was brought about by an increased efficiency of translation of the ODC message.

Amino Acids↗
PubMed1992

The role of transcription and messenger RNA stability in the regulation of epidermal growth factor receptor gene expression in regenerating mouse liver.

The influence of partial hepatectomy on epidermal growth factor receptor gene expression was studied in mouse liver. Epidermal growth factor receptor binding and epidermal growth factor receptor messenger RNA levels in the liver showed a rapid peak 8 hr after partial hepatectomy, whereas the sham operation had no effects on these levels. The peak epidermal growth factor receptor messenger RNA level was approximately threefold higher than preoperative values. The increase in epidermal growth factor receptor messenger RNA levels occurred primarily as a consequence of an increase in the rate of transcription. Partial hepatectomy slightly increased the half-life of epidermal growth factor receptor messenger RNA in the liver from 2.8 to 3.6 hr. Treatment of partially hepatectomized mice with cycloheximide increased hepatic epidermal growth factor receptor messenger RNA levels about fivefold by prolonging the half-life of the messenger RNA to 11.2 hr, although this treatment inhibited the increase in transcription induced by partial hepatectomy. Cycloheximide also increased epidermal growth factor receptor messenger RNA levels in the liver or kidney of sham-operated mice about threefold, primarily through stabilizing epidermal growth factor receptor messenger RNA. In contrast, cycloheximide had no effects on beta-actin messenger RNA levels in the liver and kidney. These results suggest that transcription induced by partial hepatectomy requires protein synthesis and that labile proteins are involved in the regulation of the stability of epidermal growth factor receptor messenger RNA.

Actins↗
PubMed1992

Multicentre trial of ABO-incompatible kidney transplantation. Japanese Biosynsorb ABO-incompatible kidney transplant study group.

A multicentre study of ABO incompatible kidney transplantation using Biosynsorb was started in Japan in November 1989. A total of 51 cases were registered comprising 23 cases of A incompatibility, 26 cases of B incompatibility and two cases of AB incompatibility. The removal of antibodies (IgG and IgM) was carried out using Biosynsorb in 16 cases, plasmapheresis in four cases and use of both combined in 31 cases. The treatment using Biosynsorb was repeated 3.4 times on average. Serum titres of anti-A (IgG and IgM) antibodies decreased to 4.9 +/- 5.0 and 2.7 +/- 1.7 and for anti-B titres decreased to 2.8 +/- 3.5 and 2.4 +/- 3.2. Rejection was found in 33 cases: hyperacute one, accelerated acute five, and acute 27. In two cases rejection was developed concomitantly with a steep elevation in antibody titres. Three patients died, two with functioning grafts. Eight grafts were lost. Patient and graft survivals at 2 years were 94.1% and 84.3%, respectively. From these results it is concluded that: 1. Biosynsorb and plasmapheresis are effective in removing anti-A and anti-B antibodies; 2. graft and patient survivals are similar to those in ABO compatible cases; 3. anti-A and anti-B titres less than 16 are recommended at the time of transplantation; 4. anti-A and anti-B titres higher than 128 may be considered as a risk factor for rejection in the early stages after transplantation.

ABO Blood-Group System↗
PubMed1992

Clinical factors which influence the long-term survival of kidney allografts donated from haploidentical donors.

All patients with renal transplants are very much concerned about their chance of long-term graft function. Chronic rejection is the most common cause of decline in function and graft failure, and after the first post-transplant year, 3-4% of recipients lose their graft every year. However, the cause, time of onset and mechanism of decline in graft function are not clear. Also unclear is whether clinical and laboratory parameters may predict patients who are at risk of developing chronic rejection. The aim of this study was to find the marker which may determine long-term graft survival in the azathioprine era and in the cyclosporine era.

Biomarkers↗
PubMed1992

Immunocytochemical localization of Bombyx-PTTH-like molecules in neurosecretory cells of the brain of the migratory locust, Locusta migratoria. A comparison with neuroparsin and insulin-related peptide.

Using a monoclonal antibody directed against a synthetic pentadecapeptide corresponding to the N-terminus of the prothoracicotropic hormone (PTTH) of Bombyx mori, we report the presence of immunoreactive molecules in a large number of median neurosecretory cells of the pars intercerebralis of the migratory locust, Locusta migratoria. These cells correspond to the A1 cell type which we show to contain also neuroparsins, a family of predominant neurohormones of the migratory locust. In contrast, PTTH-like molecules are absent from A2 cells of the pars intercerebralis which contain Locusta insulin-related peptide (LIRP). Developmental studies show the presence of PTTH-related substances in neurosecretory cells of Locusta migratoria from late embryogenesis to adult development, including ageing vitellogenic female adults.

Amino Acid Sequence↗
PubMed1992

Immunohistochemical study on the distribution of sarcoplasmic reticulum calcium ATPase in various human tissues using novel monoclonal antibodies.

Novel monoclonal antibodies were raised against sarcoplasmic reticulum calcium (Ca2+)-ATPase of human skeletal muscle. Immunohistochemical analysis demonstrated that these antibodies, designated 6F5 and 7F10, bind Ca(2+)-ATPase of non-muscle tissue of the adult including parathyroid, islets of Langerhans, anterior lobe of the pituitary gland and photoreceptor cells of the retina as well as skeletal muscle. A positive reaction was also found for fetal tissues including skeletal muscle, heart, chondrocytes and peripheral nerves. Our results for distribution suggest that Ca(2+)-ATPase is strongly expressed in the tissues and cells in which signal transduction is actively carried out by Ca2+ release from the cytoplasmic Ca2+ pool.

Antibodies, Monoclonal↗
PubMed1992

Epithelioid sarcoma: an electron-microscopic, immunohistochemical and DNA flow cytometric analysis.

Eight epithelioid sarcomas (ES) were studied by electron microscopy, immunohistochemistry, and DNA flow cytometry. Ultrastructurally, the tumour cells showed desmosome-like intercellular junctions and numerous microvilli, in addition to whorled arrangements of intermediate filaments. Tumour cells were positive for epithelial membrane antigen, cytokeratin, and vimentin, and negative for carcinoembryonic antigen and desmin. All seven cases examined by flow cytometry showed diploid or hyperploid (near diploid) DNA content. This seems to correspond to the relatively long clinical course and low-grade malignant nature of ES. Although the histogenesis of ES is still uncertain, the results of this study suggest that it is a tumour of primitive mesenchymal cells with the capacity to show epithelial differentiation.

Adult↗
PubMed1992

5c,11c,14c-eicosatrienoic acid and 5c,11c,14c,17c-eicosatetraenoic acid of Biota orientalis seed oil affect lipid metabolism in the rat.

The effects of 5c,11c,14c-eicosatrienoic acid (20:3BSO) and 5c,11c,14c,17c-eicosatetraenoic acid (20:4BSO), polyunsaturated fatty acids (PUFA) contained in Biota orientalis seed oil (BSO), on lipid metabolism in rats were compared to the effects of fats rich in linoleic acid (LA) or alpha-linolenic acid (ALA) under similar conditions. The potential effect of ethyl 20:4BSO as an essential fatty acid also was examined in comparison with the ethyl esters of LA, ALA and gamma-linolenic acid (GLA). BSO- and ALA-rich fat decreased the concentration of plasma total cholesterol, high density lipoprotein cholesterol, triglyceride and phospholipid as compared to LA-rich fat. BSO was more effective in reducing plasma cholesterol concentrations than was the ALA-rich fat. Dietary BSO markedly decreased the hepatic triglyceride concentration as compared to the LA-rich or ALA-rich fats. Aortic production of prostaglandin I2 tended to decrease in rats fed BSO or ALA-rich fat compared to those fed the LA-rich fat. Adenosine diphosphate-induced platelet aggregation was similar in the three groups. The proportion of arachidonic acid (AA) in liver phosphatidylcholine (PC) of rats fed BSO was lowest compared to that of rats fed ALA-rich or LA-rich fats. Administration of 20:4BSO, ALA or GLA to essential fatty acid-deficient rats decreased the ratio of 20:3n-9 to AA in liver PC to the same extent; administration of LA was more effective. The results indicate that the effects of specific PUFA contained in BSO on lipid metabolism are different from those of LA and ALA. It is also suggested that 20:4BSO may exhibit some essential fatty acid effects.

Adipose Tissue↗
PubMed1992

Macrophage colony stimulating factor prevents the progression of atherosclerosis in Watanabe heritable hyperlipidemic rabbits.

The early atherosclerotic lesion is characterized by the presence of macrophage-derived foam cells. Macrophage colony stimulating factor (M-CSF) specifically stimulates the functions of the monocyte-macrophages. To elucidate the effects of M-CSF in the atherogenic process in vivo, we administered human recombinant M-CSF into Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model for familial hypercholesterolemia. Three hundred micrograms of M-CSF were intravenously injected into WHHL rabbits aged 2.5 months, three times a week for 8.5 months. After the M-CSF treatment, we found very retarded progression of atherosclerosis. The accumulation of cholesterol ester was remarkably decreased in the aortae of M-CSF-treated animals (0.60 +/- 0.32 mg/g tissue), as compared to those of controls (4.32 +/- 0.61 mg/g tissue). Furthermore, the percentage of the surface area of the aorta with macroscopic plaque in animals treated with M-CSF was 14.3 +/- 6.2%, much less than that in controls receiving saline injection (38.8 +/- 8.0%). Thus, M-CSF definitely prevented the progression of atherosclerosis in WHHL rabbits by influencing macrophage functions.

Animals↗
PubMed1992

Phase 1 clinical tests of influenza MDP-virosome vaccine (KD-5382).

MDP-virosome vaccine, which contains haemagglutinin (HA) and neuraminidase (NA) antigens isolated from influenza virus combined with 6-O-(2-tetradecylhexadecanoyl)-N-acetylmuramoyl-L-alanyl-D-isoglutamine) (B30-MDP) and cholesterol was tested, in comparison with a currently used HA vaccine, for immunogenicity and adverse reactions on 77 adult male volunteers. The volunteers were divided into eight groups, and each individual was injected subcutaneously once, or twice at a 4 week interval, in their upper arm with one of seven different MDP-virosome vaccine preparations or with HA vaccine as control. Of the three virus strains used as vaccine antigens, MDP-virosome vaccines induced higher haemagglutination inhibiting (HI) antibody to A/Yamagata/120/86 (H1N1) and A/Fukuoka/C29/86 (H3N2) than did HA vaccine, whereas it induced lower HI antibody to B/Nagasaki/1/87, comparable with that induced by HA vaccine. Regarding local adverse reactions, MDP-virosome vaccinees frequently developed mild local pain, reddening and swelling, which disappeared within 5 days; as regards systemic no adverse reactions, leucocytosis developed among the MDP-virosome vaccines, but no other reactions were observed. The leucocytosis may have been caused by the pharmacoimmunological activity of B30-MDP derivatives.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

Ontogeny of DNA synthetic rhythms in chick (Gallus domesticus) liver.

1. The diurnal pattern of DNA synthesis and mitotic activity in neonatal (1-4-day-old) chick liver were investigated under various feeding and lighting regimens. 2. In the meal-fed chicks under the condition of light-dark cycle, DNA synthesis exhibited a 12 hr cycle; the peaks occurring at 9:00 and 21:00. 3. Fasting caused a gradual decrease in the 21:00 peaks. 4. The changes in the lighting regimen to 24 hr continuous lighting also caused a profound change in the DNA-synthetic pattern, suggesting a complex interplay of feeding and lighting regimens in the manifestation of the DNA-synthetic rhythm in neonatal chick liver.

Animals↗
PubMed1992

Characterization of antibody responses of local lymph nodes to antigen given under the oral submucosa.

We studied the function of submandibular lymph nodes (MLN) in the oral mucosa immune system as compared with that of inguinal lymph nodes (ILN) in the cutaneous one. Primary IgM, IgG and IgA antibody responses in MLN to sheep red blood cells (SRBC) as a model antigen given submucosally occurred more extensively than those in ILN to the antigen injected subcutaneously. Particularly, definite IgA synthesis was seen in MLN but not in ILN. This IgA synthesis was shown to be originated locally in oral submucosal lymphoid tissue or MLN but not in gut-associated lymphoid tissue (GALT). This suggested that the oral mucosal tissue including MLN acts like Peyer's patches in GALT for IgA synthesis. When mice were administered with SRBC and bacterial lipopolysaccharide (LPS) submucosally, the adjuvant effect of LPS was only observed on the capacity of MLN cells for secondary antibody response in vitro. This contrasted to the marked augmentation by LPS of both the primary antibody response in ILN and capacity for in vitro secondary antibody response of ILN cells of mice given SRBC and LPS subcutaneously. The radioactivities detected in the local lymph nodes and other tissues of mice given 51Cr labeled SRBC submucosally or subcutaneously were comparable with each other. MLN, however, contained more Ig+/B220+ B cells and less Thy1+/Ly-1+ T cells than ILN did, and the L3T4/Ly-2 ratio of T cell subpopulations in MLN was lower than that in ILN. Partially corresponding to this observation, the B cell-dependent area was developed more extensively in MLN than in ILN. This difference in cellular composition and organization might in part explain the reason why MLN and ILN display distinct modes of response and sensitivity to the action of LPS.

Animals↗
PubMed1992

Similarity, in molecular structure and function, between the plant toxin purothionin and the mammalian pore-forming proteins.

Many proteins containing domains of a cysteine-rich repeated motif, such as epidermal growth factor (EGF), have been reported. Here we report strong similarity between the amino acid sequence of a plant toxin--i.e., purothionin and its homologues--and with those of a domain found in mammalian pore-forming cytoplasmic proteins: components of complement and perforin of cytotoxic T-lymphocytes or natural killer-like cytotoxic cells. These similar sequences were found to be identical to the so-called EGF-like cysteine-rich repeated motif itself. Electron-microscopic observations indicated that, like complement and perforin, purothionin forms pores in the cytoplasmic membrane of target cells, resulting in their death within a few hours. On the basis of these sequence comparisons and physiological functions, we propose a scheme for the evolution of proteins containing modules of the cysteine-rich repeat motif.

3T3 Cells↗