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M Murayama

Publications and source records attributed to M Murayama.

At least 217 records · Page 12Linked to original sources
PubMed1988

Evidence for disulfide bonds in membrane-bound and solubilized opioid receptors.

The effects of pretreatment with dithiothreitol (DTT) on opioid binding activities of membrane-bound and digitonin-solubilized opioid receptors from bovine adrenal medulla were studied. Pretreatment of membranes with DTT or mercaptoethanol inhibited [3H]diprenorphine binding by reducing the number of binding sites. The inhibitory action of DTT was time and dose dependent. The binding of [3H]D-Ala2-D-Leu5-enkephalin was also inhibited by DTT pretreatment. Pretreatment of digitonin-solubilized binding sites with DTT also reduced the number of [3H]diprenorphine binding sites. The action of DTT was diminished by preincubating the DTT solution with H2O2. [3H]Diprenorphine protected the opioid binding sites from the inhibitory action of DTT. The present results provide evidence that disulfide bonds are implicated in opioid binding activity of the opioid receptor system.

Adrenal Medulla↗
PubMed1988

[High resolution ultrasound examination in the diagnosis of the undescended testis in the inguinal region].

Twenty-six undescended testes in 22 patients between 1 and 31 years old were evaluated with ultrasonographic examination between October, 1981 and December, 1985. All 22 patients were operated on, and the accuracy of the ultrasonic diagnosis was evaluated in comparison to that of palpation diagnosis. Fourteen of 26 testes could be palpated preoperatively and these were all identified ultrasonographically and surgically. Twelve testes could not be palpated. On these 12 testes, surgical exploration revealed 9 testes in the inguinal region and absence of 3 testes. Ultrasound examination predicted its presence in 5 of 9 testes and its absence in all 3 testes. Both sonography and palpation failed to identify their presence in 4 tests. Thus, sensitivity of ultrasound examination was 82.6%, specificity 100% and accuracy 84.6% retrospectively. We conclude that ultrasound examination is useful in diagnosis of impalpable undescended testes in inguinal region.

Adolescent↗
PubMed1988

Androgenic regulation of epidermal growth factor in the mouse ventral prostate.

Castration of adult male mice caused a marked reduction in the amount of immunoreactive epidermal growth factor (EGF) in the ventral prostate, and the treatment of such castrated mice with testosterone increased the EGF level significantly. Gel filtration of prostate extract showed that the immunoreactive EGF in the prostate had the same molecular weight (6,045) as the submandibular gland EGF. Moreover, its isoelectric point (pH 4.5) was almost similar to that (pH 4.55) of the submandibular gland peptide. These results suggest that under the control of androgens, mouse ventral prostate synthesizes EGF structurally and functionally identical to the submandibular gland EGF.

Androgens↗
PubMed1988

[Correlation between histological grading and the prognosis of prostatic carcinoma--a comparative study of the Japanese General Rules of Prostatic Cancer (JGRPC) and Gleason's classification].

One hundred and sixty-seven patients with newly diagnosed, previously untreated prostatic adenocarcinoma, during the period between July, 1971 and March, 1934, were studied. The histopathologic specimens of the prostate were classified by the Japanese General Rules of Prostatic Cancer (JGRPC) and by Gleason's classification. The number of patients with well, moderately and poorly differentiated prostatic carcinomas according to the JGRPC classification was 42, 74 and 51 respectively, and the number of the patients with Gleason's pattern 1, 2, 3, 4, and 5 was 24, 20, 32, 43 and 48, respectively. The number of patients with Gleason's score (primary plus secondary pattern) 2 to 4, 5 to 7 and 8 to 10 groups was 40, 76 and 51 respectively. There was no significant difference in survival rate between well and moderately differentiated groups, but the survival rate of the group with poorly differentiated tumor was significantly lower than that of the moderately differentiated (p less than 0.01) and well differentiated (p less than 0.001) groups. There was no significant difference in 10-year survival rate between the score 2-4 and score 5-8 groups, but the score 9-10 group had a significantly lower survival rate than the score 5-8 group (p less than 0.01) and score 2-4 (p less than 0.005) group. JGRPC and Gleason's classification are thought to be equally useful in estimating prognosis of prostatic cancer, but the former is more concise and easily applicable than the latter.

Adenocarcinoma↗
PubMed1987

[Characterization of adrenal medullary opioid receptors. I. Binding of opioids to adrenal medullary opioid receptors].

We studied the binding of [3H]D-Ala2-D-Leu5-enkephalin ([3H]DADLE) and [3H] diprenorphine to crude plasma membrane fraction obtained from the bovine adrenal medulla (bovine adrenal medullary membranes) in order to characterize adrenal medullary opioid receptors. The [3H] diprenorphine binding was the highest in crude plasma membrane-mitochondrial fraction among all subcellular fractions studied. The amount of [3H] diprenorphine bound to bovine adrenal medullary membranes was proportional to the protein concentration. Association kinetics of the [3H] diprenorphine binding to bovine adrenal medullary membranes showed that the maximal binding was achieved following 8 min incubation and that the binding conformed the second-order kinetics. [3H] DADLE and [3H] diprenorphine bound to bovine adrenal medullary membranes with high affinities. The Kd and Bmax for the [3H] DADLE binding were found to be 2.9 nM and 57.5 fmole/mg protein, respectively, while those for the [3H] diprenorphine binding were 0.31 nM and 250 fmole/mg protein, respectively. Displacement studies showed that the [3H] diprenorphine binding was inhibited dose-dependently by levorphanol, dynorphin (1-13), beta-endorphin and DADLE. Levorphanol was at least 1000-fold more potent to inhibit the [3H] diprenorphine binding than dextrorphan, indicating stereospecificity of the [3H] diprenorphine binding. Na+, Li+ and K+ (100 mM) diminished the [3H] DADLE binding and enhanced [3H] diprenorphine binding. Na+ (100 mM) increased the Kd value for the [3H] DADLE binding from 2.9 nM to 14.1 nM. Mn++, Ca++ and Mg++ diminished the [3H] diprenorphine binding. Mn++ (1 mM) increased the Bmax value for the [3H] DADLE binding from 95 fmole/mg protein to 450 fmole/mg protein. These effects of Na+ and Mn++ on the [3H] diprenorphine binding were found to be dose-dependent. [3H] Diprenorphine binding to the digitonin-solubilized opioid receptor was also inhibited dose-dependently by Mn++. These results suggest that bovine adrenal medullary membranes contain high affinity and stereospecific opioid receptors and that the binding of opioids to the bovine adrenal medullary opioid receptors is influenced by cations. Binding study also revealed the presence of opioid receptors in human malignant pheochromocytoma. The Kd and Bmax of the [3H] diprenorphine binding to crude membrane fraction obtained from malignant pheochromocytoma were found to be 0.14 nM and 10.4 fmole/mg protein, respectively.

Adrenal Medulla↗
PubMed1987

[Characterization of adrenal medullary opioid receptors. II. Coupling of adrenal medullary opioid receptors to GTP binding proteins].

We studied possible coupling of opioid receptors to GTP-binding proteins to clarify the mechanism(s) of opioid action in bovine adrenal medullary membranes. Guanylyl imidodiphosphate (Gpp(NH)p) reduced the binding of [3H] D-Ala2-D-Leu5-enkephalin ([3H] DADLE) to bovine adrenal medullary membranes dose-dependently, and enhanced the binding of [3H] diprenorphine to them. Gpp(NH)p (0.1 mM) enhanced the Kd value of the [3H] DADLE binding from 2.9 nM to 3.9 nM, but did not change its Bmax. Pretreatment of bovine adrenal medullary membranes with pertussis toxin (PT) reduced the [3H] DADLE binding. The Gpp(NH)p inhibition for [3H] DADLE binding was diminished by the PT-pretreatment. On the other hand, the [3H] diprenorphine binding to PT-pretreated membranes was higher than that to control membranes. Levorphanol inhibited the adenylate cyclase activity of the rat caudate nucleus crude synaptosomal fraction, but did not change that of bovine adrenal medullary membranes. These results suggest that opioid receptors in bovine adrenal medullary membranes are coupled to PT-sensitive GTP-binding protein which may not influence on adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1987

[Pharmacokinetics of prednisolone (PSL) during PSL treatment. II. PSL pharmacokinetics during intermittent treatment with PSL administration 4 consecutive days a week].

Pharmacokinetics of prednisolone (PSL) was investigated in 10 patients treated with long-term intermittent regimen of PSL administration, 4 consecutive days administration a week. In 8 patients (group I; 3 of nephrotic syndrome, 2 of SLE, and each of Crohn's disease, aortitis syndrome, and hemolytic anemia), PSL was initially administered daily until the therapeutic effects were achieved (daily period), and this was followed by consecutive 4 days administration (on-day) and consecutive 3 days discontinuation (off-day) of PSL every week (intermittent period), keeping the weekly dose of PSL in the preceding daily regimen. In 2 patients (group II) with multiple myeloma and idiopathic thromocytopenic purpura, respectively, PSL was started with the intermittent regimen of PSL without preceding daily period. In group I, pharmacokinetic studies by respective oral and i.v. administrations of 40mg PSL and of 25.6mg PSL hemisuccinate (equivalent to 20mg of PSL) were performed before treatment, in daily period and both on on-day and off-day within the same week during intermittent period. In one patient of group II, study only by intravenous PSL administration was performed before treatment and in intermittent period. In another patient of group II, studies by oral and intravenous PSL administration were performed only in an intermittent period. PSL was measured by radioimmunoassay. Paired t-test was used for the comparison. In each case of group I, there was no difference in Cmax, Tmax, or AUCp.o. after oral administration of PSL among 4 periods tested, before treatment, daily period, on-day and off-day during intermittent period. On the intravenous PSL administration, increase in AUCi.v., prolongation of half-life, and decreases in MCR and bioavailability on on-day of intermittent period were observed in comparison with those before treatment, respectively. Only bioavailability among these parameters on on-day was increased compared with that in daily period. On the other hand, on off-day of intermittent period, decrease in AUCi.v. and increase in MCR were observed compared with those on on-day within the same week. When each parameter on off-day was compared with that of daily period, decrease in AUCi.v. and increases in MCR and bioavailability on off-day were observed. Vd did not differ each other among these 4 periods. Remarkable finding was the fact that MCR fluctuated regularly in 4 periods of this therapy regimen, i.e., significant decrease in daily period compared with before treatment, no significant difference between on-day and daily period, and the increase on off-day compared with that on on-day or in daily period.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

Compression inhibits aggregation of human platelets under high hydraulic pressure.

It has been found in our laboratory that compression induces disaggregation and decompression induces aggregation of human platelets. The experimental design was based on the premise that oppositely charged amino acid residues of fibrinogen are juxtaposed in the specific adhesive site(s). This can be explained by the principle of Le Chateller. Under compression, electrically charged groups gain layers of water molecules which are radially oriented and pulled in closer to the center of the charge, thus making the layer more compact. This increases the thickness of the shield, thus inactivating or disaggregating the platelets. Conversely, decompression drives the water away from the compact shield; water molecules are randomized into the bulk phase; the shield becomes thinner, thus permitting spontaneous aggregation of platelets. It is well known that increasing the concentration of neutral salt can inhibit platelet aggregation. This is due to the increase of ionic strength which attenuates the electric charge and thickens the shield. Molecules having a large electric dipole moment can inhibit platelet aggregation by a similar mechanism. It is generally accepted that fibrinogen is involved in platelet aggregation. However, it is not known whether or not fibrinogen is essential for platelet aggregation inducible by decompression. Here we present data indicating that fibrinogen is essential in decompression-inducible platelet aggregation. We also present experimental data which show that high hydraulic pressure inhibits platelet aggregation, consistent with our premise that electrically charged groups are involved in the initial phase of platelet aggregation.

Blood Platelets↗
PubMed1987

Response of plasma adrenal steroids to synthetic ACTH under ketoconazole in man.

We have investigated the effect of a single oral administration of 600 mg ketoconazole, an imidazole derivative used in clinical practice as an antimycotic agent, on the response of plasma adrenocortical steroids to 1-24 ACTH in 5 normal male subjects pretreated with dexamethasone. The 2 mg of dexamethasone was administered orally at 2300 h on the preceding night, and then a rapid ACTH test was started at 0830 h. After a 1 week interval, the ACTH test was repeated in the same manner under the same dexamethasone pretreatment, but 600 mg of ketoconazole was given orally at 0500 h. The absolute plasma concentration and the increase over the basal level of each steroid after ACTH were evaluated and compared in both conditions with and without ketoconazole administration. A single ingestion of ketoconazole caused a decrease in both indices of the responsiveness of plasma dehydroepiandrosterone and a rise in the plasma level of 17 alpha-hydroxypregnenolone. The response of plasma aldosterone was clearly blunted by ketoconazole administration, whereas that of plasma corticosterone was clearly increased. Ketoconazole also blocked the response of plasma cortisol with concomitantly increased responses of plasma 11-deoxycortisol and 11-deoxycorticosterone. The increased response of plasma corticosterone seemed to be likely due to the severe inhibitory action of ketoconazole on the conversion of corticosterone to aldosterone. These results imply the inhibitory effect of ketoconazole on C17-20-lyase activity and on the conversion of corticosterone to aldosterone, and suggest an inhibitory action on 11 beta-hydroxylase activity. The effects of ketoconazole on the other enzyme activities in adrenal steroid biosynthesis were also discussed.

17-alpha-Hydroxypregnenolone↗
PubMed1987

Solubilization of adrenal medullary opioid receptors.

The opioid-binding activity of digitonin extract of bovine adrenal medullary membranes was studied. [3H]Diprenorphine binding to the solubilized material was rapid and saturable. The dissociation constant of [3H]diprenorphine binding was 0.76 nM. Several opioids displaced the [3H]diprenorphine binding. The complex of [3H]diprenorphine and the solubilized binding sites was eluted as a single peak on a Sepharose 6B column and showed an apparent molecular weight of 200,000. These results indicate that active opioid receptors are solubilized with digitonin from bovine adrenal medullary membranes.

Adrenal Medulla↗