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Biomedical subjects

S Miura

Publications and source records attributed to S Miura.

At least 19 recordsLinked to original sources
PubMed1992

Neurotoxins: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1,2,3,4-tetrahydroisoquinoline and 1-methyl-6,7-dihydroxy-tetrahydroisoquinoline as substrates for FAD-containing monooxygenase of porcine liver microsomes.

The activity of FAD-containing monooxygenase (FMO) (EC 1.14.13.8) of porcine liver microsomes was examined with the neurotoxins, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-6,7-dihydroxy-tetrahydroisoquinoline (MDTIQ), as substrates. FMO catalyses these neurotoxins. The kinetic parameters of FMO for the neurotoxins and electron donors were determined. Km values for MPTP, TIQ and MDTIQ were determined to be 47 microM, 6.9 mM and 5.6 mM, respectively. The Km for the electron donor, NADPH, was variable from 31 to 200 microM depending on the substrate used. The activities of FMO for these neurotoxins were comparable with that for dimethylaniline.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1992

The interaction of botrocetin with normal or variant von Willebrand factor (types IIA and IIB) and its inhibition by monoclonal antibodies that block receptor binding.

We have recently shown the existence of two distinct forms of botrocetin (one-chain and two-chain), and demonstrated that the two-chain species is approximately 30 times more active than the one-chain in promoting von Willebrand factor (vWF) binding to platelet glycoprotein (GP) Ib. The N-terminal sequence of two-chain botrocetin is highly homologous to sea-urchin Echinoidin and other Ca(2+)-dependent lectins (Fujimura et al., Biochemistry 1991; 30: 1957-64). Present data indicate that purified two-chain botrocetin binds to vWF from plasmas of patients with type IIA or IIB von Willebrand disease and its interaction is indistinguishable from that with vWF from normal individuals. However, an "activated complex" formed between botrocetin and IIB vWF expresses an enhanced biological activity for binding to GP Ib whereas the complex with IIA vWF has a decreased binding activity. Among several anti-vWF monoclonal antibodies (MoAbs) which inhibit ristocetin-induced platelet aggregation and/or vWF binding to GP Ib, only two MoAbs (NMC-4 and RFF-VIII RAG:1) abolished direct binding between purified botrocetin and vWF. This suggests that they recognize an epitope(s) on the vWF molecule in close proximity to the botrocetin binding site.

Antibodies, Monoclonal↗
PubMed1992

Absorbance spectral change of the cytochrome P-450S21-phenylisocyanide complex upon binding of reduced NADPH-cytochrome-P-450 reductase.

Reduction of cytochrome P-450S21 (SF) (SF, substrate-free; purified from bovine adrenocortical microsomes) with sodium dithionite (Na2S2O4) in the presence of phenylisocyanide produced a ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex with Soret absorbance maxima at 429 and 456 nm. On the other hand, when a preformed ferric cytochrome P-450S21 (SF)-NADPH-cytochrome-P-450 reductase (Fp2) complex was reduced chemically or enzymatically under the same conditions, the absorbance spectrum of the ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex changed drastically, as characterized by an increase in absorbance intensity at 429 nm and a decrease at 456 nm. Similar spectral changes were observed by addition of reduced Fp2 to the preformed ferrous cytochrome P-450S21 (SF)-phenylisocyanide complex. Experiments to reduce a ferric cytochrome P-450S21 (SF)-phenylisocyanide complex with sodium dithionite in the presence of various amounts of Fp2 showed that; (1), the spectral change reached maxima for both absorption increase at 429 nm and decrease at 456 nm when cytochrome P-450S21 and Fp2 were previously mixed at the cytochrome P-450S21:Fp2 ratio of 1:5; (2), the spectral change was suppressed in 300 mM potassium phosphate buffer (pH 7.4). These results suggest that the absorbance spectral change is due to a conformational change around the heme moiety induced by association with reduced Fp2.

Adrenal Cortex↗
PubMed1992

Carboxyl-terminal consensus Ser-Lys-Leu-related tripeptide of peroxisomal proteins functions in vitro as a minimal peroxisome-targeting signal.

The minimal sequence requirement for a peroxisome-targeting signal was investigated using an in vitro import system. Carboxyl-terminal sequences Ser-Lys-Leu (SKL) and Leu-Gln-Ser-Lys-Leu (LQSKL) of acyl-CoA oxidase (AOX) directed to peroxisomes the fused proteins with import-incompetent forms of AOX and catalase that had been truncated, implying that the SKL tripeptide functions as a targeting signal. Elimination of the entire SKL sequence or deletion of any 1 or 2 amino acids in the sequence abolished the import activity of AOX. Substitution of alanine for serine did not affect the import activity. Topogenic activity was retained when lysine was mutated to either arginine or histidine, whereas mutation to glutamic acid completely abolished the activity. A synthetic peptide comprising the carboxyl-terminal 10 amino acid residues of AOX inhibited the import of the authentic AOX polypeptide, whereas other peptides in which SKL was mutated, deleted, or internally located were not effective. The uptake of AOX was little affected by the peptide with an amidated alpha-carboxyl group. These results strongly suggest that the carboxyl-terminal SKL motif sequence (Ser/Ala)-(Lys/Arg/His)-Leu functions as a topogenic signal in translocation of proteins into peroxisomes, requiring the whole tripeptide sequence with a free alpha-COOH group at the carboxyl terminus.

Acyl-CoA Oxidase↗
PubMed1992

Visualization of oxidative processes at the cellular level during neutrophil-mediated cytotoxicity against a human hepatoma cell line, HCC-M.

Human neutrophil-mediated oxidative processes against a human hepatoma cell line, HCC-M, was visualized at the cellular level by using a silicon-intensified target camera and subsequently processing with a computer-assisted digital-imaging processor. Neutrophils were activated by a streptococcal preparation, OK-432. A hydroperoxide-sensitive tracer, dichlorofluorescein diacetate, was loaded in HCC-M and temporal and spatial changes of lipid peroxides in this cell after addition of stimulated neutrophils were analyzed. The luminol-dependent chemiluminescence activity of neutrophils was significantly enhanced and continued for at least 2 hr by stimulation with OK-432, and its activity was shown to be accumulated at the site where a neutrophil attached with HCC-M. The intensity of dichlorofluorescein fluorescence in HCC-M rapidly increased after adding stimulated neutrophils, and their reaction was significantly attenuated by superoxide dismutase. The number of non-viable cells was increased as the dichlorofluorescein fluorescence increase. It is suggested that oxidative stress may play an important role in neutrophil-mediated tumor-cell damage.

Carcinoma, Hepatocellular↗
PubMed1992

Independent protective effect of lactation against breast cancer: a case-control study in Japan.

A case-control study was carried out to assess the risk of breast cancer associated with breast feeding in Japan. The data were obtained in a hospital-based case-control study of 521 women with breast cancer and 521 controls from January 1988 to December 1989. Statistical adjustment for potential confounders as well as a likelihood ratio test for linear trend was done by unconditional logistic regression. Compared with parous women who had never breast-fed, women with a positive history of breast feeding had an odds ratio of breast cancer of 0.62 (95% confidence interval 0.37-1.04). The trend of decreasing risk with increasing average months of breast feeding was statistically significant (chi 2 trend = 4.5, p less than 0.05), while it was was nonsignificant for the number of breast-fed children borne. Among premenopausal women, a significant linear relation with a log-transformed term of average months of breast feeding was noted, regardless of the age of the woman at first full-term pregnancy and parity (chi 2 trend = 5.3, p less than 0.05). The risk was the lowest among premenopausal women who had ever lactated for 7-9 months (adjusted odds ratio = 0.39, 95% confidence interval 0.15-0.97). These findings suggest that lactation has an independent protective effect against breast cancer in Japanese women.

Adult↗
PubMed1992

Role of steroid 11 beta-hydroxylase and steroid 18-hydroxylase in the biosynthesis of glucocorticoids and mineralocorticoids in humans.

A gene encoding steroid 18-hydroxylase (P-450C18) was isolated from a human genomic DNA library. It was identified as CYP11B2, which was previously postulated to be a pseudogene or a less active gene closely related to CYP11B1, the gene encoding steroid 11 beta-hydroxylase (P-45011 beta) [Mornet, E., Dupont, J., Vitek, A. & White, P. C. (1989) J. Biol. Chem. 264, 20961-20967]. The nucleotide sequence of the promoter region of the P-450C18 gene is strikingly different from that of the P-45011 beta gene, although the sequences of their exons are 93% identical. The transient expression in Y-1 adrenal tumor cells of CAT constructs with a series of deletion mutants of promoter regions of both genes indicated that the two genes are regulated differently. P-450C18 as expressed in COS-7 cells exhibits steroid 18-hydroxylase activity to catalyze the synthesis of aldosterone and 18-oxocortisol and exhibits steroid 11 beta-hydroxylase activity as well. In contrast, P-45011 beta as expressed in the cultured cells exhibits steroid 11 beta-hydroxylase activity exclusively but fails to catalyze the synthesis of aldosterone and 18-oxocortisol. These results indicate that P-45011 beta and P-450C18 are products of two different genes and that the former participates in the synthesis of glucocorticoids whereas the latter participates in the synthesis of mineralocorticoids in humans.

Amino Acid Sequence↗
PubMed1992

Relative effect of steroid hormone receptors on the prognosis of patients with operable breast cancer. A univariate and multivariate analysis of 3089 Japanese patients with breast cancer from the Study Group for the Japanese Breast Cancer Society on Hormone Receptors and Prognosis in Breast Cancer.

In a retrospective multicenter study to investigate the correlation between estrogen (ER) and/or progesterone receptors (PgR) in primary breast cancer with patient prognosis, 3118 patients with operable breast cancer (International Union Against Cancer Stages I, II, and III) were investigated from ten hospitals in Japan who underwent surgery from October 1972 to December 1982; 3089 were evaluable. The ER-positive and PgR-positive cancers were found in 56% and 34% of patients, respectively. The positivities decreased as the tumor size increased but were independent on lymph node metastasis. There were no significant differences in relapse-free survival (RFS) in relation to receptor status (median follow-up, 89 months [ER], 84 months [PgR]). However, in patients with four or more positive nodes, those with PgR-positive cancer had a longer RFS. The patients with ER-positive cancer survived significantly longer than ER-negative ones, with the greatest difference seen in those with four or more positive nodes. There was a significantly longer postrelapse survival (PRS) for patients with ER-positive cancer because of the different distribution of the major metastasis and better responses to first-line and subsequent treatments. Cox's multivariate analysis showed that overall survival but not PRS was affected by ER (and more weakly by PgR) because of the longer PRS in patients with ER-positive cancer.

Adult↗
PubMed1992

Tissue-type plasminogen activator of colonic mucosa in ulcerative colitis. Evidence of endothelium-derived fibrinolytic activation.

Microvascular endothelial alterations are thought to be a crucial step for development of hemorrhagic changes in various pathological states. In this study, we determined the activity and amount of tissue-type plasminogen activator (t-PA) in the biopsy specimens from sigmoid colon of patients with ulcerative colitis to evaluate endothelial alterations and vascular changes of permeability. The results of this investigation revealed that mucosal amount of t-PA in the active stage of ulcerative colitis was two- to threefold higher than in healthy controls, while t-PA levels in plasma samples showed no remarkable differences among the groups. Increased t-PA activity appeared to correlate well to the degree of inflammation of colonic mucosa, and t-PA amount was still increased in the inactive stage. The present study indicates that t-PA determination in colonic biopsy specimens may be useful for the evaluation of clinical activity of ulcerative colitis in terms of the mucosal microvascular endothelial changes.

Adult↗
PubMed1992

A case-control study of breast cancer among Japanese women: with special reference to family history and reproductive and dietary factors.

To study the effects of family history and reproductive, anthropometric, and dietary factors on the risk of breast cancer among low risk populations, we conducted a hospital-based case-control study involving 908 patients with breast cancer and their matched controls, in Japan. A positive family history of breast cancer significantly increased the risk of breast cancer (odds ratio = 1.52, 95% confidence interval: 1.14-2.03). The risk further increased with increasing number of family members affected. Obesity, single marital status, fewer births, a late childbirth, and less consumption of green-yellow vegetables and dairy products were also associated with an increased risk of breast cancer. These associations were independent in multivariate analyses. There was no increase in risk associated with consumption of high fat foods. When analyzed by menopausal status, the association with family history of breast cancer, especially in the first degree of relatives, was more evident for premenopausal breast cancer. The associations with obesity and lower consumption of dairy products were more pronounced for postmenopausal breast cancer, while those with lower parity and single marital status were stronger for premenopausal breast cancer.

Adult↗
PubMed1992

Villous component as a marker for synchronous and metachronous colorectal adenomas.

To determine whether patients with colorectal adenomas containing a villous component (+vc group) have a higher incidence of synchronous or metachronous colorectal adenomas, 527 consecutive cases of completely removed colorectal adenoma were used. Synchronous adenomas were detected in 22.6 percent and 19.0 percent of the patients in the +vc and -vc groups, respectively. In the analysis of metachronous adenomas, 164 patients who had been followed for 1 to 11 years (mean, 3.31 years) were included. The cumulative adenoma-free rate according to Kaplan-Meier tended to be lower in the +vc group, the difference being statistically significant 1.0 to 1.2 years after treatment of the initial adenoma and the two curves being different based on the generalized Wilcoxon test. The numbers of newly detected adenomas annually were 1.76 and 0.86, and their annual incidences were 1.09 and 0.59 times, in the +vc and -vc groups, respectively. These results suggest the importance of the villous component as a predictor of metachronous colorectal adenomas.

Adenoma↗
PubMed1992

Bowel preparation for the total colonoscopy by 2,000 ml of balanced lavage solution (Golytely) and sennoside.

One of disadvantages of the Golytely preparation is that examinees have to drink as much as 4,000 ml of Golytely. To overcome this disadvantage, we designed a modified preparation regimen in which examinees have to drink only 2,000 ml of Golytely by taking sennoside orally. Bowel preparation was carried out in 297 examinees by this modified method. Examinees ate their usual diet and took 36 mg of sennoside orally on the night before the examination. On the day of the examination, the examinees drank a total of 2,000 ml of Golytely. No severe complications were noted and 97% of the examinees were able to drink the dose of 2,000 ml. Subjects who had also experienced bowel preparation by the modified method of Brown were asked to compare the two regimens, and only 1% preferred Brown's method while 73% preferred bowel preparation by our Golytely method. The result of bowel preparation by this method was excellent or good in 90 to 97% of the subjects at all sites in the colon and rectum. We conclude that bowel preparation for total colonoscopy using 2,000 ml of Golytely and sennoside is superior because it is highly acceptable to the examinees and provides excellent gut irrigation.

Adolescent↗
PubMed1992

Protective effect of ren-shen-yang-rong-tang (Ninjin-youei-to) in mice with drug-induced leukopenia against Pseudomonas aeruginosa infection.

When 200 mg/kg of cyclophosphamide (CY) or 5-fluorouracil (5-FU) were given subcutaneously to mice, severe reduction of leukocyte numbers in the peripheral blood was observed on day 4 and from day 4 to day 8 after the treatment, respectively. Daily administration of ren-shen-yang-rong-tang (Japanese name: Ninjin-youei-to, NYT), (1 g/kg/day) and recombinant human granulocyte-colony stimulating factor (rhuG-CSF, 2 micrograms/mouse/day) either from day 0 to day 4 after treatment with CY or from day 0 to day 8 after treatment with 5-FU accelerated the recovery of peripheral leukocytes. Administration of NYT and rhuG-CSF inhibited decreases in the number of colony forming units in the spleen (CFU-S) in drug-treated mice. In mice infected intraperitoneally with a virulent strain of Pseudomonas aeruginosa 4 days and 8 days after treatment with CY and 5-FU, respectively, lethal doses were much lower (approximately 1/1000) than that in normal mice. Administration of NYT and rhuG-CSF to drug-treated mice inhibited the enhanced bacterial growth in the peritoneal cavity. Administration of NYT or rhuG-CSF to drug-treated mice enhanced the recovery of accumulation of leukocytes into the infected peritoneal cavity from their depressed state. Administration of NYT was more effective for improving the host resistance of 5-FU-treated mice than for improving that of CY-treated mice in contrast to rhuG-CSF which exhibited stronger effect in CY-treated mice than in 5-FU treated mice.

Animals↗
PubMed1992

The future of 5-HT1A receptor agonists. (Aryl-piperazine derivatives).

At present the dominant position among anti-anxiety medications has changed from meprobamate to the benzodiazepine derivatives. In order to avoid benzodiazepine's (BZ) undesirable side effects such as impairment of psycho-motor function, memory impairment, low dose dependence and withdrawal symptoms, a third generation anxiolytic agent, buspirone, the focus of the aryl-piperazine group of anti-anxiety agents, has been introduced recently. Aryl-piperazine derivatives work as 5-HT1A receptor partial agonists and are known as serotonin normalizers. Therefore, they are expected to have not only an anxiolytic function but also an anti-depressant effect as well. A characteristic of the aryl-piperazine derivatives is that they have no sedative and muscle relaxant effects, and they do not have BZ's undesirable side-effects, especially in regard to withdrawal symptoms. However they have a rather weak anxiolytic action and a slow onset of action. Aryl-piperazine derivatives will not take the place of BZ, but the use of BZ and buspirone as bridge medications, making the most of the strong points of both, can be proposed as a way to compensate for their respective clisadvantages.

Animals↗
PubMed1992

A convenient method for regional monoamine oxidase-A determination by [14C]clorgyline autoradiography.

The availability of clorgyline for regional monoamine oxidase-A (MAO-A) determination was examined using [14C]clorgyline in rat. [14C]Clorgyline was synthesized by the methylation reaction of N-desmethyl-clorgyline and [14C]methyliodide in dimethylformamide with high radiochemical yield. The MAO-A distribution map by autoradiography correlated with that by histochemical technique and its quantity was consistent with the calculated MAO-A amount based on previous reports. The combination of labeled clorgyline and autoradiographic technique will promise the quantitative measurement of regional MAO-A distribution.

Animals↗
PubMed1992

Detection of viral DNA within skin of healed recurrent herpes simplex infection and erythema multiforme lesions.

The polymerase chain reaction (PCR) was used to detect HSV DNA in genomic DNA extracted from skin biopsies obtained from healed skin of five patients with hyperpigmented macules following recurrent cutaneous HSV infections and from eight patients with HSV-associated erythema multiforme (EM). A 92-bp HSV-1 DNA fragment was found in all the skin biopsies from the site of recurrent HSV infection and in five of eight (62%) biopsies from the EM patients. Virus DNA was not found in tissues distant from the site of HSV recurrence or from a patient without a history of HSV infection. These findings confirm the presence of HSV in healed skin from the site of recurrent HSV disease and are consistent with the concept that HSV is involved in EM pathogenesis.

Adolescent↗
PubMed1992

Species difference among experimental rodents in induction of P450IA family enzymes by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine.

Rats, mice, hamsters and guinea pigs were given an i.p. injection of 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP), a protein-derived pyrolysate component present in cooked foods, and inductions of cytochrome P450 (P450) in the liver and kidney of these animals were examined. The activity and amount of P450s corresponding to the rat P450IA1 and P450IA2 were assessed by means of a bacterial mutation test using 3 carcinogenic heterocyclic aromatic amines including PhIP as substrates and by Western blotting with a monoclonal antibody reactive with both P450IA1 and P450IA2. In rats, PhIP induced P450IA1, P450IA2 and a new but unspecified P450 isozyme in the liver, and induced P450IA1 in the kidney. However, PhIP induced none of these P450 isozymes in mice, hamsters and guinea pigs.

Amines↗