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Biomedical subjects

H Sawada

Publications and source records attributed to H Sawada.

At least 19 recordsLinked to original sources
PubMed1992

The 26 S proteasome is activated at two points in the ascidian cell cycle.

The proteasome undergoes cell cycle-dependent changes in its subcellular distribution during ascidian embryonic development [(1992) Dev. Biol. 151, 27-33]. In this study, we demonstrate that the 26 S proteasome is markedly activated in both prophase and metaphase of the mitotic cell cycle in the ascidian embryos in comparison with the case of the 20 S proteasome. These results suggest that the 26 S proteasome is activated and participates in proteolysis at the restricted stages of the cell cycle.

Animals↗
PubMed1992

Chemical modification of cysteinyl, lysyl and histidyl residues of mouse liver 17 beta-hydroxysteroid dehydrogenase.

Monomeric 17 beta-hydroxysteroid dehydrogenase from mouse liver was rapidly inactivated by 5,5'-dithiobis(2-nitrobenzoic acid) and 2,4,6-trinitrobenzene-1-sulfonate, and the absorption spectra of the inactivated enzymes indicated that cysteine and lysine residues were modified. The kinetics of inactivation and spectrophotometric quantification of the modified residues suggested that complete inactivation was caused by modification of two cysteine residues or one lysine residue per active site. The inactivation by the two reagents was protected by NADP+ and some coenzyme analogs, but not by a steroid substrate, testosterone. Moreover, chemical modification by diethyl pyrocarbonate also produced inactivation of the enzyme, and showed a difference spectrum with a peak at 242 nm characteristic of N-carbethoxyhistidine residues, which decreased with the addition of hydroxylamine. The inactivation by this reagent, following pseudo-first-order kinetics, was protected partially by either NADP+ or testosterone and completely in the presence of both the coenzyme and substrate. The results suggest the presence of essential cysteine and lysine residues at or near the coenzyme-binding site and that of essential histidine residue(s) in the catalytic region of the active site of mouse liver 17 beta-hydroxysteroid dehydrogenase.

17-Hydroxysteroid Dehydrogenases↗
PubMed1992

Structural and functional comparison of two human liver dihydrodiol dehydrogenases associated with 3 alpha-hydroxysteroid dehydrogenase activity.

Two monomeric dihydrodiol dehydrogenases with pI values of 5.4 and 7.6 were co-purified with androsterone dehydrogenase activity to homogeneity from human liver. The two enzymes differed from each other on peptide mapping and in their heat-stabilities; with respect to the latter the dihydrodiol dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase activities of the respective enzymes were similarly inactivated. The pI 5.4 enzyme was equally active towards trans- and cis-benzene dihydrodiols, and towards (S)- and (R)-forms of indan-1-ol and 1,2,3,4-tetrahydronaphth-1-ol and oxidized the 3 alpha-hydroxy group of C19-, C21- and C24-steroids, whereas the pI 7.6 enzyme showed high specificity for trans-benzene dihydrodiol, (S)-forms of the alicyclic alcohols and C19- and C21-steroids. Although the two enzymes reduced various xenobiotic carbonyl compounds and the 3-oxo group of C19- and C21-steroids, and were A-specific in the hydrogen transfer from NADPH, only the pI 5.4 enzyme showed reductase activity towards 7 alpha-hydroxy-5 beta-cholestan-3-one and dehydrolithocholic acid. The affinity of the two enzymes for the steroidal substrates was higher than that for the xenobiotic substrates. The two enzymes also showed different susceptibilities to the inhibition by anti-inflammatory drugs and bile acids. Whereas the pI-5.4 enzyme was highly sensitive to anti-inflammatory steroids, showing mixed-type inhibitions with respect to indan-1-ol and androsterone, the pI 7.6 enzyme was inhibited more potently by non-steroidal anti-inflammatory drugs and bile acids than by the steroidal drugs, and the inhibitions were all competitive. These structural and functional differences suggest that the two enzymes are 3 alpha-hydroxysteroid dehydrogenase isoenzymes.

3-Hydroxysteroid Dehydrogenases↗
PubMed1992

Purification and characterization of pig lung carbonyl reductase.

A pyrazole-sensitive carbonyl reductase from pig lung was purified to homogeneity by electrophoretic criteria. Chemical cross-linking study suggested that the native enzyme is a tetramer with a Mr of 103,000, consisting of apparent identical subunits of Mr 24,000. The enzyme reduced aliphatic and aromatic carbonyl compounds with NADPH as a preferable cofactor to NADH and catalyzed the oxidation of secondary alcohols and the aldehyde dismutation in the presence of NAD(P)+. Immunohistochemical study with the antibodies against the enzyme revealed that the enzyme was localized in the ciliated cells, nonciliated bronchiolar cells, Type II alveolar pneumocytes, and the epithelial cells of the ducts of the bronchial glands in the pig lung. In addition to the properties and distribution, the pig lung enzyme was immunochemically similar to the pulmonary enzymes in the guinea pig and mouse. However, the pig enzyme showed the following unusual features. (1) The enzyme exhibited an equatorial specificity in the reduction of 3-ketosteroids; the 4-pro-S hydrogen of NADPH was transferred to the carbonyl carbon atom of 5 alpha- and 5 beta-androstanes, and the respective reduced products were identified as 3 beta- and 3 alpha-hydroxysteroids. (2) Although the NADPH-linked reduction of carbonyl compounds apparently obeyed the Michaelis-Menten kinetics at pH 6.0, the double-reciprocal plots of the velocity vs concentrations of the carbonyl substrates were convex at pH higher than 6.5. The Hill coefficients and [S]0.5 values for the substrates decreased as the pH for reaction increased. The results suggest that the pig enzyme exhibits negative cooperativity with respect to the carbonyl substrates and that the hydrogen ion acts as an allosteric effector abolishing the negative interaction.

Alcohol Dehydrogenase↗
PubMed1992

Activation of carbonyl reductase from pig lung by fatty acids.

The NADPH-linked reductase activity of pig lung carbonyl reductase was activated two- to fivefold by fatty acids with a carbon chain length greater than nine at pH 7.0. cis-Unsaturated fatty acids of C:18 and C:20 were potent activators, showing Ka values of 2-14 microM which were lower than the values of 21-125 microM for saturated fatty acids (C:9 to C:16). Of the fatty acids arachidonic acid (C20:4) gave the highest activation. No significant stimulatory effect was observed with acyl CoAs, fatty alcohols, phospholipids, and nonionic detergents. Anionic detergents (sodium dodecyl sulfate and sarkosyl) stimulated the enzyme activity more than ninefold, but the Ka values for them were much higher than those for the cis-unsaturated fatty acids. Although no change in molecular weight or in subunit composition was observed in the enzyme activated by C20:4, the activation led to a decrease in thermal stability of the enzyme. The binding of C20:4 to the enzyme was instantaneous and reversible, shifted the pH optimum of the activity from 5.8 to 6.5, and changed the inhibitor sensitivity. In addition, C20:4 acted as an allosteric effector abolishing the negative interaction of the enzyme with carbonyl substrates which was seen without the fatty acid, but the activation increased both Vmax and [S]0.5 values for the substrates. Kinetic analysis with respect to NADPH concentration, in which no cooperativity was detected with or without C20:4, indicated that C20:4 was a nonessential activator of mixed type showing a binding constant of 10 microM. These results suggest that cis-unsaturated fatty acids may be potential modulators of pulmonary carbonyl reductase.

Alcohol Oxidoreductases↗
PubMed1992

MRI and SPECT findings in amyotrophic lateral sclerosis. Demonstration of upper motor neurone involvement by clinical neuroimaging.

MRI was performed in 21 patients and single photon emission computed tomography (SPECT) with N-isopropyl-p-123I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11.

Adult↗
PubMed1992

Accessory nerve neuroma presenting as recurrent jugular foramen syndrome.

We report a patient with spontaneous recovery and recurrence of a jugular foramen syndrome secondary to an accessory nerve neuroma. He showed sudden onset of unilateral palsy of the ninth, tenth and eleventh cranial nerves in 1982. He recovered almost fully and in 1990 the palsies recurred. MRI revealed a small mass in the right jugular foramen. The tumour was resected via suboccipital craniectomy, and diagnosed as a neuroma of the eleventh cranial nerve.

Accessory Nerve↗
PubMed1992

Participation of 650-kDa protease (20 S proteasome) in starfish oocyte maturation.

A protease involved in oocyte maturation of a starfish, Asterina pectinifera, was explored. Trypsin-like and chymotrypsin-like activities of the 650-kDa protease in oocyte extract were revealed to increase more than twice under the influence of 1-methyladenine before germinal vesicle breakdown (GVBD) during maturation. The inhibitory potencies of leupeptin and its five analogs against the chymotrypsin-like activity, but not the trypsin-like activity, of this protease was well in accord with those against GVBD (Takagi Sawada et al. (1989). Dev. Biol. 133, 609-612). These results indicate that the chymotrypsin-like activity of the 650-kDa protease (most probably 20 S proteasome) plays a key role in starfish oocyte maturation.

Amino Acid Sequence↗
PubMed1992

Modification of pig liver dimeric dihydrodiol dehydrogenase with diethylpyrocarbonate and by rose bengal-sensitized photooxidation: evidence for an active-site histidine residue.

Dihydrodiol dehydrogenase from pig liver was inactivated by diethylpyrocarbonate (DEP) and by rose bengal-sensitized photooxidation. The DEP inactivation was reversed by hydroxylamine and the absorption spectrum of the inactivated enzyme indicated that both histidine and tyrosine residues were carbethoxylated. The rates of inactivation by DEP and by photooxidation were dependent on pH, showing the involvement of a group with a pKa of 6.4. The kinetics of inactivation and spectrophotometric quantification of the modified residues suggested that complete inactivation was caused by modification of one histidine residue per active site. The inactivation by the two modifications was partially prevented by either NADP(H) or the combination of NADP+ and substrate, and completely prevented in the presence of both NADP+ and a competitive inhibitor which binds to the enzyme-NADP+ binary complex. The DEP-modified enzyme caused the same blue shift and enhancement of NADPH fluorescence as did the native enzyme, suggesting that the modified histidine is not in the coenzyme-binding site of the enzyme. The results suggest the presence of essential histidine residues in the catalytic region of the active site of pig liver dihydrodiol dehydrogenase.

Alcohol Oxidoreductases↗
PubMed1992

SPECT findings in Parkinson's disease associated with dementia.

Dementia in Parkinson's disease is thought to be attributable not only to subcortical lesions but also to cortical alterations, especially frontal lobe dysfunction. To evaluate cortical function, the regional cerebral blood flow (rCBF) was estimated of 13 demented and 13 non-demented age matched patients with Parkinson's disease compared with that of 10 age matched controls using I-123 iodoamphetamine single photon emission tomography (IMP-SPECT). The rCBF of the nondemented Parkinson's patients showed no significant differences from that of the control subjects. In the demented patients, the bilateral frontal and parietal and left temporal regional blood flow was significantly less than in the controls. Four demented patients showed isolated frontal hypoperfusion, 8 showed fronto-parietal hypoperfusion, and 1 showed isolated parietal hypoperfusion. Frontal hypoperfusion was therefore present in 12 of the 13 demented patients, and this finding agrees with the frontal lobe dysfunction hypothesis. Parietal rCBF had a significant positive correlation with cortical functions such as calculation and language ability in the MMSE scores. The parietal and temporal reduction in rCBF probably reflects the presence of Alzheimer pathology, cortical Lewy body disease, or both.

Aged↗
PubMed1992

The properties of monoclonal antibody against sepiapterin reductase from fat body of the silkworm, Bombyx mori.

A specific monoclonal antibody prepared for the 29-kDa a subunit of silkworm fat body sepiapterin reductase (SPR) was able to recognize the subunit in crude extract of fat body after SDS treatment. Although SPR from the silkworm fat body has biochemical properties similar to those reported for SPR from mammalian sources, especially rat erythrocytes, the antibody failed to recognize the 28-kDa subunit of rat erythrocyte SPR. This result indicates that SPR from silkworm fat body has a different amino-acid sequence from that of the rat erythrocyte enzyme. Sepiapterin reductase activity has not been found in crude extract of fat body from the silkworm mutant lemon. Although the antibody recognized only 29-kDa protein in the crude extract of silkworm fat body from normal strain after SDS-treatment, the antibody recognized only an approximately 80-kDa protein in the crude extract of the lemon mutant after SDS-treatment.

Alcohol Oxidoreductases↗
PubMed1992

The potential for the development of liver metastasis from alpha-fetoprotein-producing human gastric carcinomas in nude mice.

The potential for liver metastasis in addition to the transplantability and doubling time of alpha-fetoprotein(AFP)-producing and non-AFP-producing human gastric carcinomas were studied in nude mice. The potential for liver metastasis was analyzed histopathologically from intrasplenic injections of tumor cell suspensions prepared from subcutaneous tumors. Tumor fragments prepared aseptically from 15 AFP-producing and 140 non-AFP-producing gastric cancers were subcutaneously transplanted into nude mice with transplantability rates of 80% (12/15 cases) and 50% (70/140 cases), respectively. The mean tumor doubling times in the first generation were 10.6 days for AFP-producing and 13.2 days for non-AFP-producing gastric carcinomas. Serially transplantable tumor lines in nude mice were established from six AFP-producing and 10 non-AFP-producing carcinomas. When tumor cell suspensions prepared from the subcutaneous tumors were injected into spleens, all six AFP-producing carcinomas (two poorly differentiated and four tubular adenocarcinomas) but only four out of the 10 non-AFP-producing carcinomas (two poorly differentiated adenocarcinomas, one mucinous carcinoma and one papillary adenocarcinoma) demonstrated a potential for liver metastasis. The results indicate AFP-producing gastric carcinomas to possess a higher potential for liver metastasis than do non-AFP-producing carcinomas, a distinguishing feature which thus reflects a poor prognosis.

Adenocarcinoma↗
PubMed1992

Phorbol ester alters carbachol-stimulated diacylglycerol formation in parotid acinar cells through the hydrolysis of phosphoinositides and phosphatidylcholine.

Incubation of rat parotid acinar cells with phorbol 12,13-dibutyrate (PDBu) resulted in inhibition of carbachol-stimulated formation of sn-1,2-diacylglycerol (DAG). PDBu pretreatment inhibited carbachol-induced turnover of phosphoinositides; this inhibition was indicated by phosphatidylinositol 4,5-bisphosphate breakdown. This pretreatment also attenuated the effect of carbachol on inositol phosphate generation and phosphatidylcholine hydrolysis. These results show that PDBu alters carbachol-stimulated DAG formation through the hydrolysis of phosphoinositides and phosphatidylcholine.

Animals↗
PubMed1992

Long-term observation of neutralization antibody after enterovirus 70 infection.

There is the need for more information on the persistence of the immune response to enterovirus 70 (EV70) infection. In August 1984, an outbreak of acute hemorrhagic conjunctivitis occurred at a nursing home in Sapporo, Japan. During the subsequent 7 years, we have monitored the neutralization antibody of EV70 in 13 patients with acute hemorrhagic conjunctivitis and 15 persons with subclinical EV70 infection among the 108 persons in the nursing home. During the first one to two years, the neutralization antibody in 6 of the 28 subjects (21.4%) decreased to less than 1:8. Seven years later, the neutralization antibody had decreased to less than 1:8 in 92% of the subjects. There was an individual difference in the level of neutralization antibody titer against EV70. However, overall the antibody levels markedly decreased every year. It is important to remember that the neutralization antibody titer of EV70 decreases with the passage of time. Consequently, most of the patients who had acute hemorrhagic conjunctivitis will not have resistance against reinfection 7 years after the initial infection.

Adult↗
PubMed1992

[Influence of systolic left ventricular blood flow direction on genesis of senile calcification of the aortic valve].

To assess the factors which may initiate and accelerate degenerative senile calcification of the aortic valve, two-dimensional echocardiograms and the clinical characteristics of 259 consecutive cases with senile calcification of the aortic valve were studied. The results were compared with those of similar studies among 186 consecutive cases with the normal aortic valves. An aortic cusp with an area of increased echo greater than 3 mm in width and with decreased pliability was regarded as calcified. Among patients with calcification of one aortic cusp, 114 exhibited calcification of a noncoronary cusp, 17 calcification of the left coronary cusp and 3 calcification of the right coronary cusp (p < 0.001). Among patients with calcification of 2 aortic cusps, 39 had calcification of a noncoronary and left coronary cusps, 3 calcification of the left and right coronary cusps and 16 calcification of the right and noncoronary cusps (p < 0.001). In patients with calcification of their aortic valves, the end-diastolic angle between the interventricular septum and the ascending aorta was 102 +/- 10 degrees; whereas, it was 89 +/- 10 degrees in the control group (p < 0.001). There were no differences in frequency of aortic root calcification, mitral annular calcification, hypertension, ischemic heart disease, hyperlipidemia, hyperuricemia, or hyperglycemia, between patients with and without calcification of their aortic valves. Of the female patients ranging in age from 65 to 74 years, 88% in those with calcification of 3 cusps and 30% in those with calcification of one cusp (p < 0.05) had mitral annular calcification.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Echocardiographic assessment of aortic regurgitation and aortic root dilatation in bicuspid aortic valve].

Aortic regurgitation (AR) and aortic root dilatation in 29 consecutive patients with bicuspid aortic valves but without aortic root disease (20 males, and 9 females: aged 27-85 years) were studied using two-dimensional echocardiography. The normal ranges of aortic root dimensions were calculated from values of 185 normal subjects, as 95% confidence intervals. AR was observed in 17 patients by color flow mapping. In 12 of the 17 AR patients, no significant lesion of the aortic cusp was detected by two-dimensional echocardiography. These 12 AR patients were compared with 12 patients without AR. Increase in dimension of the aortic root was relatively frequent in the 12 AR patients at the aortic annulus (AA) (67 vs 17%, p < 0.05), and at the sinus of Valsalva (A1) (67 vs 17%, p < 0.05). At the ascending aorta 5 mm distal to the sinus of Valsalva (A2), the difference was not significant (58 vs 17%, p < 0.09). The 12 bicuspid AR patients without significant lesions of the aortic cusp were compared with 41 AR patients with normal tricuspid aortic valves. The frequencies of cases with increased aortic root dimension were 67 vs 46% (ns) at the AA, 67 vs 22% (p < 0.05) at A1 and 58 vs 5% at A2 (p < 0.01). Thus, aortic annular dilatation was thought to be the cause of AR in bicuspid and tricuspid aortic valves without significant lesions of the aortic cusps, and generalized dilatation of the aortic root was more frequent in bicuspid AR patients than in tricuspid AR patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗