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Biomedical subjects

M Okuno

Publications and source records attributed to M Okuno.

At least 19 recordsLinked to original sources
PubMed1992

Differentiation-dependent expression of retinoid-binding proteins in BFC-1 beta adipocytes.

Recently, we demonstrated that adipose tissue plays an important role in retinol storage and retinol-binding protein (RBP) synthesis. Our data suggested that RBP expression in adipose tissue is dependent on the state of adipocyte differentiation. To examine this possibility, we explored the differentiation-dependent expression of RBP using BFC-1 beta preadipocytes, which can be stimulated to undergo adipose differentiation. Total RNA was isolated from undifferentiated (preadipocytes) and differentiated (adipocytes) BFC-1 beta cells and analyzed by Northern blotting. RBP mRNA was not detected in the preadipocytes, but considerable RBP mRNA was present in differentiated BFC-1 beta cells. In BFC-1 beta cells, induced to differentiate with insulin and thyroid hormone, RBP mRNA was first detected after 4 days, reached a maximum level by day 10, and remained at this maximum level for at least 2 more days. Cellular retinol-binding protein was expressed at low levels in the BFC-1 beta preadipocytes and the level of expression increased for 6 days after induction to differentiate and slowly declined on later days. Neither the maximum level of RBP expression nor the day on which this level was reached was influenced by the level of retinol provided in the BFC-1 beta culture medium. BFC-1 beta cells secreted newly synthesized RBP into the culture medium at a rate of 43 +/- 14 ng RBP/24 h/10(6) adipocytes. When the BFC-1 beta adipocytes were provided 1.0 microM retinol in the medium, they accumulated the retinol and synthesized retinyl esters. These studies with BFC-1 beta cells confirm that RBP synthesis and secretion and retinol accumulation are intrinsic properties of differentiated adipocytes. Furthermore, they suggest that RBP and cellular retinol-binding protein gene expression are regulated as part of a package of genes which are modulated during adipocyte differentiation.

Adipose Tissue↗
PubMed1992

Retinoids and retinoid-binding protein expression in rat adipocytes.

Adipose tissue has been reported to contain relatively high levels of the specific mRNA for retinol-binding protein (RBP) (Makover A., Soprano, D.R., Wyatt, M. L., and Goodman, D.S. (1989) J. Lipid Res. 30, 171-180). Studies were conducted to explore retinoid and retinoid-binding protein storage and metabolism in adipose tissue. In these studies, we measured RBP and cellular retinol-binding protein (CRBP) mRNA levels and retinoid levels in 6 adipose depots in male rats. Total RNA was isolated from inguinal, dorsal, mesenteric, epididymal, perinephric, and brown adipose tissue, and average RBP and CRBP mRNA levels were determined by Northern blot analysis. The relative levels of RBP mRNA in these 6 anatomically different adipose depots averaged, respectively, 6.3, 6.7, 16, 34, 37, and 21% of the level in a rat liver RNA standard. Retinoid levels in the 6 depots were similar and averaged approximately 6-7 micrograms of retinol eq/g of adipose tissue. Since adipose tissue contains several cell types, the cellular localizations of RBP and CRBP expression and retinoid storage were examined. RNA was prepared from isolated rat adipocytes and stromal-vascular cells. Cellular levels of the mRNAs for RBP, CRBP, apolipoprotein E (apoE), lipoprotein lipase, adipocyte P2, and adipsin were measured by Northern blot analysis. RBP was expressed almost exclusively in the adipocytes and only weakly in the stromal-vascular cells. Both CRBP and apoE mRNA levels were relatively high in the stromal-vascular cell preparations and only very low mRNA levels were found in the adipocytes. Lipoprotein lipase, adipsin, and adipocyte P2 mRNAs were found in substantial levels in both the adipocytes and stromal-vascular cells, but with higher levels present in the adipocytes. Cultured adipocytes synthesized RBP protein and secreted it into the medium. Only adipocytes (not stromal-vascular cells) contained retinol, at levels between 0.65-0.8 micrograms of retinol eq/10(6) cells. These studies demonstrate that adipocytes store retinoid and synthesize and secrete RBP, and suggest that rat adipocytes may be dynamically involved in retinoid storage and metabolism.

Adipose Tissue↗
PubMed1992

Peptide YY enhances NaCl and water absorption in the rat colon in vivo.

Peptide YY (PYY) is thought to possess paracrine and endocrine functions. The highest concentrations of this peptide are in the colonic mucosa. The effect of PYY on electrolyte and water transport in the rat colon was studied in vivo. Under urethane anesthesia, rat colonic loops were perfused at a constant rate with physiological buffer solution containing phenol red as a nonabsorbable volume marker, and net movements of water, sodium, chloride and potassium in the perfused colon were determined every 10 min. Intravenous administration of PYY produced a dose-dependent increase in the net absorption of sodium chloride and water, as well as a decrease in the net secretion of potassium. PYY inhibited the reduction in net absorption of sodium chloride and water evoked by vasoactive intestinal peptide (VIP), but did not affect the VIP-evoked increase in net potassium secretion. These findings suggest that PYY acts as an enhancer of sodium chloride and water absorption and as an antagonist to VIP-induced secretion in the colon.

Animals↗
PubMed1992

Purification and characterization of a sperm motility-dynein ATPase inhibitor from boar seminal plasma.

A sperm motility inhibitor from boar seminal plasma was purified. The purification procedure included dialysis against 0.1 M Tris-HCl containing 0.1 mM DTT and chromatographies on SP-Sephadex C-25 and Phenyl-Sepharose CL-4B. With this procedure, the seminal plasma motility inhibitor (SPMI) preparation was highly purified with a 18% recovery of inhibitory activity. The molecular weight of SPMI in native conditions has been estimated at 50,000 by molecular sieving, but 3 polypeptides with molecular weights of 14,000, 16,000 and 18,000 were observed following polyacrylamide gel electrophoresis in denaturing conditions. SPMI is a thermolabile basic protein that is stable between pH 6 and pH 11. The observations that SPMI effects on motility of demembranated spermatozoa are reversed by Mg.ATP and that SPMI inhibited bull dynein ATPase in a concentration-dependent manner suggest that this protein blocks the motility of demembranated spermatozoa by interfering with dynein arm function.

Animals↗
PubMed1992

Analysis of tubulin isoforms by two-dimensional gel electrophoresis using SDS-polyacrylamide gel electrophoresis in the first dimension.

A two-dimensional electrophoretic system using SDS-polyacrylamide gel electrophoresis (SDS-PAGE) in the first dimension and isoelectric focusing (IEF) in the second dimension was devised. In spite of its simplicity, this method could show a markedly high resolution for tubulin isoforms and moreover could classify them into alpha- or beta-tubulin as a two-dimensional profile. With this method, seven alpha- and four beta-tubulin isoforms could be detected within axoneme from Tetrahymena cilia. Moreover this method could also resolve tubulin isoforms from the rabbit brain. These results indicate that the present two-dimensional gel electrophoresis is a useful tool for the electrophoretic analysis of tubulin isoforms from various sources.

Animals↗
PubMed1992

Reduced bone density and major hormones regulating calcium metabolism in anorexia nervosa.

Bone density of lumbar vertebrae (L2 to L4) and the whole body in 29 patients with anorexia nervosa were measured by dual photon absorptiometry, and the results were compared with those of 10 age-matched normal controls. The patients had significantly lower bone mineral density (BMD) in L3 and L2-4 than controls. However, there was no difference in whole-body BMD. L3 and L2-4 BMD was positively correlated with body weight and was negatively correlated with duration of illness and amenorrhea. Patients who had been more active 6 months before the time of the study had significantly higher L3 BMD than the less active patients. Most patients had an abnormally low serum estrogen level, whereas the mean serum levels of thyroid hormone (T3, T4), cortisol, calcitonin, parathyroid hormone and vitamin D were within the normal range. No correlation was found between L3 or L2-4 BMD and the levels of these hormones. These results suggest that severe weight loss, low physical activity, longer duration of amenorrhea and deficiency of estrogen contribute to bone loss in patients with anorexia nervosa, whereas calcium-regulating hormones such as parathyroid hormone, calcitonin and vitamin D are unlikely to be a primary contributor to bone loss.

Adolescent↗
PubMed1992

Galanin-induced alteration of electrolyte transport in the rat intestine.

Effects of rat and porcine galanin on rat intestinal ion transport were examined in vitro. In the rat distal colon, a sustained increase in short-circuit current (Isc) was produced by the serosal addition of rat galanin at a concentration as low as 10(-9) M, and a maximal increment was observed at 10(-7) M. Porcine galanin was approximately 100 times less potent than rat galanin. In the rat jejunum, rat galanin produced only a slight and transient decrease in basal Isc. The response to rat galanin was not influenced by atropine, hexamethonium, or amiloride, but was virtually abolished by tetrodotoxin or furosemide. Rat galanin did not significantly influence the increase in Isc elicited by electrical field stimulation in the rat colon and jejunum. Transmural unidirectional 22Na and 36Cl fluxes in the rat colonic mucosa were measured under short-circuited conditions, and rat galanin significantly decreased net sodium and net chloride absorption. These findings suggest that galanin acts as a secretory modulator in the rat colon via noncholinergic neural transmission.

Amiloride↗
PubMed1992

[Determination and clinical significance of human hepatocyte growth factor in serum].

Hepatocyte growth factor (HGF) is the most potent mitogen for mature parenchymal hepatocytes in primary culture, and seems to be a hepatotrophic factor that acts as a trigger for liver regeneration after partial hepatectomy and liver injury. In the present study, we evaluated an enzyme-linked immunosorbent assay, using monoclonal antihuman HGF (h-HGF) antibody, for measuring serum h-HGF levels. Intra- and inter-assay coefficients of variation were 2.2-3.3% and 3.4-4.0%, respectively. Detection limit of this method was 0.1 ng/ml, determining by the dilution test. The substances tested did not interfere with this assay, except for high concentrations of hemoglobin. Furthermore, no interference was observed with plasminogen and lipoprotein (a), which show the structural homology to h-HGF, and with various kinds of cytokines. Reference ranges of serum h-HGF determined with 187 healthy subjects were 0.1-0.23 ng/ml. Serum h-HGF concentrations were increased in various kinds of liver diseases, in particular those were significantly higher in fulminant hepatic failure. Furthermore, prognosis of the patients with higher h-HGF values were strikingly worse than those with lower levels. We concluded that the determination of serum h-HGF plays important roles in the early diagnosis and prognosis of fulminant hepatic failure.

Antibodies, Monoclonal↗
PubMed1992

Separation of X- and Y-chromosome-bearing murine sperm by free-flow electrophoresis: evaluation of separation using PCR.

The effectiveness of separation of murine X- and Y-bearing sperm by free-flow electrophoresis was evaluated by the polymerase chain reaction (PCR). The ratio of X- and Y-bearing sperm from cauda epididymis was analyzed before and after free-flow electrophoresis. A Y-chromosome-specific sequence (pY353/B) and an autosomal sequence (myogenin) were used to estimate the ratio between X- and Y-sperm in the separated fractions. Cauda epididymal mice sperm were separated into two peak fractions under the electric field. Each peak fraction contained sperm of normal shape, however, the motility of the sperm was extremely diminished after separation by electrophoresis. DNA was extracted from 10(4) sperm from each fraction and from the unseparated sperm, and Y-chromosome specific PCR was performed. The PCR experiment revealed that fraction No. 16 (the peak near the cathode) was a Y-sperm rich fraction, whereas fraction No. 22 (the peak near the anode) was a Y-sperm poor one. These results suggested that murine X- and Y-sperm could be successfully separated by free-flow electrophoresis. Analysis of the chromosome-specific sequence by PCR was demonstrated to be a direct and adequate method to evaluate the separation of X- and Y-sperm.

Animals↗
PubMed1991

Inner arm dynein ATPase fraction of sea urchin sperm flagella causes active sliding of axonemal outer doublet microtubule.

In order to clarify the role of the inner arms of the axoneme in sperm flagellar movement, we prepared an ATPase fraction (12S) from the outer arm-depleted axonemes of sea urchin sperm flagella. When both arm-depleted axonemes were incubated with the 12S ATPase, they exhibited the sliding disintegration of outer doublet microtubules. Electron microscopy revealed that the ATPase rebound to the original inner arm sites of the axoneme. Therefore, it is quite likely that the 12S ATPase is one of the components of the inner arms. We referred to it as "inner arm dynein".

Animals↗
PubMed1991

Reduced retinoid content in hepatocellular carcinoma with special reference to alcohol consumption.

Although alcohol is known to enhance hepatocarcinogenesis, the mechanism of this action remains to be explained. To test the hypothesis that ethanol depletes the liver of antitumor promoters such as retinoid, we measured the retinoid concentration in hepatocellular carcinoma tissues and noncancerous surrounding liver tissues in humans known to have a history of alcohol consumption. By high-performance liquid chromatography, the retinoid contents of 29 surgically resected hepatocellular carcinoma specimens and their noncancerous surrounding tissues were measured. Retinoid contents were decreased in both the cancerous and the surrounding noncancerous liver tissues of patients with a high intake of alcohol. The levels correlated inversely with the estimated cumulative lifetime ethanol consumption. The decrease in the retinoid content of hepatic parenchymal cells paralleled that in stellate cells. When compared with the surrounding liver tissues, the cancerous liver tissues were in the state of retinoid deficiency. In summary, alcohol abuse may help promote the hepatocarcinogenesis in man by depleting the liver of the antitumor promoter, retinoid.

Adult↗
PubMed1991

Nucleotide specificity of the enzymatic and motile activities of dynein, kinesin, and heavy meromyosin.

The substrate specificities of dynein, kinesin, and myosin substrate turnover activity and cytoskeletal filament-driven translocation were examined using 15 ATP analogues. The dyneins were more selective in their substrate utilization than bovine brain kinesin or muscle heavy meromyosin, and even different types of dyneins, such as 14S and 22S dynein from Tetrahymena cilia and the beta-heavy chain-containing particle from the outer-arm dynein of sea urchin flagella, could be distinguished by their substrate specificities. Although bovine brain kinesin and muscle heavy meromyosin both exhibited broad substrate specificities, kinesin-induced microtubule translocation varied over a 50-fold range in speed among the various substrates, whereas heavy meromyosin-induced actin translocation varied only by fourfold. With both kinesin and heavy meromyosin, the relative velocities of filament translocation did not correlate well with the relative filament-activated substrate turnover rates. Furthermore, some ATP analogues that did not support the filament translocation exhibited filament-activated substrate turnover rates. Filament-activated substrate turnover and power production, therefore, appear to become uncoupled with certain substrates. In conclusion, the substrate specificities and coupling to motility are distinct for different types of molecular motor proteins. Such nucleotide "fingerprints" of enzymatic activities of motor proteins may prove useful as a tool for identifying what type of motor is involved in powering a motility-related event that can be reconstituted in vitro.

Actins↗
PubMed1991

Inhibitory effect of sarcophytol A on development of spontaneous hepatomas in mice.

The inhibitory effect of sarcophytol A, a cembrane-type diterpene isolated from a marine soft coral, Sarcophyton glaucum, on development of spontaneous hepatomas was investigated in C3H/HeNCrj mice. A total of 80 mice were divided equally into two groups. The experimental and control groups were given basal diets with and without 0.01% sarcophytol A, respectively. At week 65 of the experiment, mice were examined for hepatomas. The percentages of hepatoma-bearing mice of the subgroup with three or more tumors and the tumor diameters of the group treated with sarcophytol A were smaller than those of the control group. Ridit analysis revealed that these differences were statistically significant. The body weight gain, and the food intake were not significantly different between these two groups. Analysis of blood serum revealed that feeding the diet containing 0.01% sarcophytol A for 65 weeks did not show any adverse effects. These results suggest that sarcophytol A inhibits the development of spontaneous hepatomas without toxicity, and should be considered as a possible cancer chemopreventive agent for hepatomas in humans.

Alanine Transaminase↗
PubMed1991

Zeta potential of human X- and Y-bearing sperm.

The zeta potential of human X- and Y-bearing sperm was measured by two different methods: (i) using an electrophoretic light scattering spectrophotometer, and (ii) using a laser-rotating prism. The X- and Y-bearing sperm were separated by free-flow electrophoresis, and their purities were determined by staining for the F-body using quinacrine mustard. The zeta potential of the sperm in the fraction containing more than 80% Y-bearing sperm was approximately -16 mV, whereas that of sperm in the fraction containing more than 95% X-bearing sperm was approximately -20 mV. In other words, the net negative-charge on the cell surface of human X-bearing sperm is higher than that of Y-bearing sperm.

Cell Separation↗
PubMed1991

Purification and partial characterization of rat epididymal retinoic acid-binding protein, and its immunohistochemical localization.

Two types of retinoic acid-binding proteins, designated as epididymal retinoic acid-binding protein (ERABP) types A and B, have been purified to homogeneity from rat genital organs. ERABP types A and B had molecular weights of 19,000 and 18,500 and isoelectric points of 5.72 and 5.90, respectively. The absorption spectrum of ERABP complex with retinoic acid had two peaks at 277 and 354 nm, and showed similar uncorrected fluorescence spectra to that of cellular retinoic acid-binding protein (CRABP). These ERABPs were identified as major androgen-dependent epididymal proteins by amino acid sequences analyses. Furthermore, immunohistochemical examinations revealed that the ERABPs exist in the epithelium of the proximal portion of the epididymis and in the lumen of epididymal canal and seminal tract leading from the epididymis. The existence of ERABP strongly suggests that retinoic acid might be involved in the maturation of spermatozoa.

Amino Acid Sequence↗
PubMed1991

[Usefulness and limitations of stress 201-thallium myocardial imaging in patients with Kawasaki disease].

Thallium-201 myocardial imaging was performed in 150 patients with a history of Kawasaki disease, aged 6 months to 16 years old. Forty-five patients were studied with ergometer exercise and 105 patients had dipyridamole administration. The findings of thallium imaging were compared with those of coronary angiography. Seventy-two cases with severe coronary stenosis (over 75%) were classified in 3 groups; 13 with the left anterior descending artery lesion, 31 with only the right coronary artery lesion and 28 with multi-vessel involvement. In 72 cases with severe coronary stenosis, the sensitivity of thallium imaging for detecting coronary stenotic lesions was 85%, 74% and 67% in the 3 groups, respectively. In 78 cases without severe coronary stenosis, 5 cases (6%) had persistent perfusion defects on thallium imaging, 3 of which were associated with dyskinesis of the left ventricle documented by cineangiography. They were considered to have damaged myocardium probably due to peripheral myocardial infarction or myocarditic problems. Thallium-201 myocardial imaging was proved to be a useful method to detect coronary stenosis, however its sensitivity for detecting lesions of the right coronary artery or multi-vessels was relatively low. This may be attributable to a significantly higher incidence of segmental stenosis (recanalization) with sufficient coronary flow and multiple coronary collateral vessels in patients with such lesions.

Adolescent↗