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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 577 records · Page 32Linked to original sources
PubMed1989

The potentiation of norepinephrine-induced contraction of rabbit aorta by Mg2+ deletion in a Ca2+-free medium.

Residual responses to norepinephrine (NE) in an Mg2+-, Ca2+-free medium with low EGTA (0.1 mM) for 15 min were potentiated following preincubation of rabbit aortas in Mg2+-free medium for 60 min. Responses to Ca2+ in a Ca2+-free medium with nifedipine and NE were not affected under a similar Mg2+-free condition. Nifedipine, theophylline, dibutyryl cAMP, 8-bromo-cGMP, methylene blue, La3+ or vanadate did not affect the residual response or the potentiation. However, high EGTA (1 mM) inhibited both the residual response and the potentiation. The residual response to NE was not potentiated following incubation in Mg2+-, Ca2+-free medium for 60 min. These results suggest that, in the rabbit aorta, Mg2+ deletion from the medium selectively potentiates the residual response to NE in a Ca2+-free medium without any effect on the response due to Ca2+-influx through receptor-operated channels. This potentiation does not appear to be related to either the levels of cAMP and cGMP or the activity of an Mg2+-dependent, Ca2+-ATPase.

Animals↗
PubMed1989

[Self-setting apatite cement. VII. Barium-apatite as radio-opaque medium].

Addition of barium hydroxyapatite (BaAp) successfully bestowed clinically acceptable radioopacity to the self-setting apatite cement consisting of an equimolar mixture of tetracalcium phosphate and dicalcium phosphate dihydrate. To accelerate the setting reaction which was retarded by Ba2+ released from BaAp at a lower pH during first stage of spatulation with 20 mM phosphoric acid, calcium hydroxyapatite (CaAp) was added to the cement mixture. At about 20 wt% of BaAp and 20 wt% CaAp, the setting reaction proceeded at a neutral or weak alkaline pH, which is one of the most promising aspects of the self-setting cement and assures that this type of cement may be the least irritating of the dental cements presently available. The cement spatulated at L/P = 0.4 set within 10 minutes and its radiopacity was comparable to or more than that of tooth enamel. The wet compressive strength of the set cement stored for one day in synthetic saliva at 37 degrees C was approximately 100 kgf/cm2. Although this value is almost one fourth that of 40 wt% CaAp cement, this cement appears to be strong enough to apply as root canal filling material.

Barium↗
PubMed1989

Role of dipeptidyl peptidase IV (gp 108) in passive Heymann nephritis. Use of dipeptidyl peptidase IV-deficient rats.

Injection of antibodies to renal tubular membrane (Fx1A) into Lewis rats induces granular deposits of IgG in glomeruli and proteinuria (passive Heymann nephritis, PHN), and similar lesions are also induced by antibody to one of the antigens in Fx1A, dipeptidyl peptidase IV (DPP IV, gp 108). In this study, the role of DPP IV in PHN was investigated using DPP IV-deficient F344 rats. The amount of DPP IV found in F344 rat kidneys was less than 0.05% of that present in Wistar rats, and injection of anti-DPP IV antibody into F344 rats did not induce proteinuria. Injection of anti-F344 Fx1A rabbit antibodies that contain no detectable anti-DPP IV antibody into Lewis or F344 rats induced PHN, characterized by granular deposits of rabbit IgG in glomeruli and massive proteinuria, although the appearance of proteinuria was delayed in comparison with that occurring in response to injection of anti-Wistar Fx1A antibodies. These results indicate that DPP IV may contribute to, but is not essential for, the induction of PHN.

Animals↗
PubMed1989

[Ultrastructure of capillary permeability in malignant lymphoma].

The ultrastructure of the blood vessels of primary central nervous system malignant lymphoma was studied and compared with those in glial, non-glial and metastatic brain tumors. Five surgical specimens were studied by conventional ultrathin section and freeze-fracture replica techniques. Tumor vessels of various sizes were found. The luminal surfaces of the tumor vessels were irregular and the basal lamina had multiple-layer structure. The perivascular spaces were enlarged and infiltrated with tumor cells. The endothelium had marked infoldings, increased pinocytotic vesicles and fenestrations. The intercellular junctions were short but no obvious opening was seen. On the replica specimen pinocytotic vesicles were calculated on an average of 28 per microns2. The essential features of the blood vessels in primary central nervous system malignant lymphoma were the fenestrated vessels. They resembled the blood vessels found in non-glial and metastatic brain tumors, but were distinctly different from those seen in glial tumors with non-fenestrated vessels.

Adult↗
PubMed1989

[A case of acute dissecting aneurysm of the aorta in systemic lupus erythematosus].

A 28 year-old female patient who has been diagnosed as having systemic lupus erythematosus (SLE) developed an acute dissecting aneurysm of the aorta (DeBakey type I). The long-term, large dose corticosteroid therapy (i.e., accumulative dose of about 60 g) administered for the treatment of lupus nephritis (WHO class III----IV) was considered to be responsible for a hypercholesterolemia (300-560 mg/dl) and a steroid-dependent hypertension (WHO class III) in this patient. The autopsy findings for the aorta were compatible with atherosclerotic changes but not with lupus arteritis. While atherosclerotic cardiovascular complications have been considered to be rare in patients with SLE, a growing body of evidence suggests that the incidence of such a complication may be increasing along with a dramatic improvement in the longevity of patients with SLE after an introduction of a large dose, long-term corticosteroid therapy.

Adult↗
PubMed1989

[Early diagnosis of the cervical incompetency by the ultrasonography].

To establish a reliable method for diagnosing cervical incompetency, we observed changes in the cervix by ultrasonography and tried to settle the criteria for early diagnosis. The ultrasonographic evaluation of the cervix was performed by real time B mode scanning (Aloka Echo camera SSD 650 with attached sector scanner using 3.5 MHZ transducers). The cervical length was defined as the distance from the lower edge of the fetal membranes to the edge of the portio vaginalis. In the case of normal pregnancy, the cervical length increased gradually from 14 to 24 weeks of gestation and then decreased gradually. In the case of patients who delivered before 33 weeks of gestation, the cervical length was less than -ISD. 78 of 79 cases in whom bulging of the membranes was not seen delivered at term, but 9 of 33 cases with bulging membranes delivered preterm (chi2, p less than 0.001). The criteria of cervical incompetency based on ultrasonographic findings are as follows: 1. Bulging of the fetal membranes into the endocervical canal 2. Shortening of the cervix a. the cervical length less than -ISD of the mean value b. the decrease in cervical length before 24 weeks of gestation

Cervix Uteri↗
PubMed1989

[A case of primary hypothalamic malignant lymphoma with diabetes insipidus].

A case of primary malignant lymphoma involving the hypothalamus is reported. A 31-year-old man was admitted with progressive disorientation. A computed tomography (CT) scan demonstrated a normodense, homogenously enhanced, and nodular shaped mass lesion involving the suprasellar region and extending to the third ventricle. In view of marked cerebral edema, dexamethasone was intravenously administered, at a dose of 4 mg/4 hr, and gradually tapered off. CT scans obtained 10 days after the admission revealed dramatic regression of the lesion, which corresponded with the clinical remission. However, on the 4th day after the discontinuance of corticosteroid, a CT scan demonstrated the recurrence of the mass lesion. Because of the rapid deterioration of consciousness and the progressive enlargement of the mass and dilatation of the ventricles, partial removal of tumor and ventricular drainage were carried out on the 24th day after admission. Dexamethasone was intravenously administered again at a dose of 4 mg/4 hr. A CT scan obtained five days after the operation showed complete disappearance of the lesion, and the patient had became almost alert. CT scans obtained on the 18th day and the 35th day after the operation showed complete disappearance of the mass. However, Magnetic Resonance Imaging revealed a localized area of abnormal signal intensity in the hypothalamus. Diabetes insipidus was continuously observed from the time of admission. A concomitant change of beta-2-microglobulin (beta-2-MG) and immunoglobulin (IgA, IgG, IgM) concentrations in serum and cerebrospinal fluid (CSF) with clinical profiles and CT findings were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[BANA hydrolase and DNP peptidase activities in the ovulatory process of PMS-hCG treated immature rat].

To investigate the roles of collagenolytic enzymes in the ovulatory process of PMS-hCG treated immature female rats (22 days old), we measured the activities of two of them in the ovary by the using synthetic substrates alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl (BANA) (a collagenolytic cathepsin) and dinitrophenol-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg OH (DNP peptide) (a neutral collagenase). BANA hydrolase activities significantly began to increase after the hCG injection, reaching a peak 8-9 hours later, and then decreased sharply 10 hours later. There was also a significant increase in DNP peptidase activities 7-10 hours after the hCG injection and a significant decrease 12 hours after the injection. The present study has shown that BANA hydrolase and DNP peptidase appear during the ovulatory process of PMS-hCG-treated immature female rats, and that their significant preovulatory increases are contributory to collagenolysis in follicle rupture.

Animals↗
PubMed1989

Accessory cell activity of monocytes in anti-DNA antibody production in systemic lupus erythematosus.

Depletion of monocytes from peripheral blood mononuclear cells of patients with systemic lupus erythematosus (SLE) resulted in a decreased anti-DNA antibody synthesis in vitro. The addition of monocytes restored the response by lymphocytes and the maximum response in the presence of 2.5-8% of monocytes, whereas greater than 15% of monocytes caused rather decreased antibody responses. In order to further evaluate the role of monocytes on an anti-DNA antibody synthesis, we designated an accessory cell index, based on reconstitution experiments using isologous SLE lymphocytes, and compared it in active or inactive SLE and controls. The studies revealed that active SLE monocytes enhanced spontaneously occurring anti-DNA antibody synthesis by SLE lymphocytes. These results indicate that SLE monocytes actively participate in spontaneously occurring anti-DNA autoantibody synthesis in humans.

Antibodies, Antinuclear↗
PubMed1989

[A case of primary intracranial malignant melanoma with characteristic magnetic resonance imaging].

The authors reported a rare case of primary malignant melanoma in the central nervous system and discussed the findings of MRI. A 60-year-old male was admitted for examinations to discover the cause of his generalized tonic convulsions. On admission, he had neither neurological deficits, nor were there any abnormalities revealed during physical examination. Ct scan disclosed a slightly high-density mass with perifocal edema in the right parietal cortex which enhanced markedly after injection of contrast material. This lesion was hypointense on T1 weighted image of MRI (GE: 1.5 Tesla) and a hyperintense band was observed on the surface of the tumor. On T2 weighted image, the tumor showed iso-hypointensity surrounded by an increased signal area compatible with edema. On August 31, 1988, a gross total removal of the tumor was performed. Microscopically, it was identified as a malignant melanoma. No melanoma was found in other parts of the body during careful examinations, especially in dermatologic and ophthalmologic examinations. Characteristic findings of the hyperintense band on T1 weighted image coincided well with the pathological findings of excessive melanin deposition on the surface of the tumor, and which resulted from the paramagnetic free-radicals in the melanin. MR image may be useful for differentiation of intracranial malignant melanomas from other mass lesions.

Brain Neoplasms↗
PubMed1988

Inhibition of the tumor-promoting action of 12-O-tetradecanoylphorbol-13-acetate by some oleanane-type triterpenoid compounds.

Since glycyrrhetinic acid was proved to suppress tumor promoter effects, several oleanane-type triterpenes which were chemically derived from oleanolic acid and hederagenin were tested in vitro and in vivo against the action of tumor promoter, 12-O-tetradecanoylphorbol 13-acetate. By in vitro experiment monitoring with 12-O-tetradecanoylphorbol-13-acetate-induced stimulation of 32Pi incorporation into phospholipids and an in vivo test on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene and promoted with 12-O-tetradecanoylphorbol-13-acetate, 18 beta-olean-12-ene-3 beta,28-diol (= erythrodiol), 18 beta-olean-12-ene-3 beta,23,28-triol, 18 alpha-olean-12-ene-3 beta,28-diol, and 18 alpha-olean-12-ene-3 beta,23,28-triol showed remarkable suppressive effects. Especially 18 alpha-oleanane derivatives having a CH2OH grouping converted from the COOH group initially allocated at C-17 were 100 times more effective than glycyrrhetinic acid both in vitro and in vivo.

Animals↗
PubMed1988

The structure of nephritogenoside. A nephritogenic glycopeptide with alpha-N-glycosidic linkage.

Nephritogenoside is a glycopeptide with the ability to induce chronic progressive glomerulonephritis (end stage kidney) in homologous animals, by a single footpad injection. This substance contains a novel carbohydrate-peptide linkage, i.e. the trisaccharide (3 glucose residues) chain is alpha-N-glycosidically linked to the polypeptide chain through the amido nitrogen of an asparagine residue at the N-terminal. It was found that the peptide portion of nephritogenoside is composed of twenty-one amino acids (Asn1-Pro-Leu-Phe-Gly5-Ile-Ala-Gly-Glu-Asp10-Gly-Pro-Thr-Gly-Pr o15-Ser-Gly-Ile- Val-Gly20-Gln21) and that the peptide portion has a repeated Gly-X-Y structure.

Amino Acid Sequence↗
PubMed1988

Development of a fetal circadian rhythm after disruption of the maternal circadian system.

The role of maternal circadian rhythms in the development of the fetal circadian system was investigated in the rat. Pregnant females were subjected to procedures known to disrupt circadian function, ablation of the maternal suprachiasmatic nuclei (SCN) or housing in constant illumination, on gestational day 10. Circadian function was assessed in fetuses at gestational day 22 by analysis of glucose utilization in hypothalamic slices in vitro using the 2-deoxyglucose method. Fetuses from control females exhibit a robust rhythm in glucose utilization in the SCN. In contrast, the SCN of fetuses from females with SCN lesions, or housed in constant illumination, show no significant day-night difference in glucose utilization. Analysis of individual brains indicates, however, that this apparent disruption in the development of circadian rhythmicity in metabolism in the fetal SCN is due to a desynchronization of individual fetuses resulting from the loss of maternal entraining influences. Thus, the fetal SCN is capable of developing a circadian rhythm in glucose utilization independent of the maternal circadian system.

Animals↗
PubMed1988

Electrical and metabolic activity of suprachiasmatic nucleus neurons in hamster hypothalamic slices.

Single unit neuronal activity and glucose utilization were studied in the suprachiasmatic nucleus (SCN) in hypothalamic slices from the golden hamster brain in vitro. An apparent circadian rhythm was observed both in SCN single unit activity and in glucose utilization. These observations indicate that the brain slice method is useful for the analysis of pacemaker function in hamster SCN.

Action Potentials↗