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Biomedical subjects

K Miyazaki

Publications and source records attributed to K Miyazaki.

At least 451 records · Page 25Linked to original sources
PubMed1993

Polymeric calcium phosphate cements: setting reaction modifiers.

In this study, the effects of several additives on the setting behavior and mechanical properties of polymeric calcium phosphate cements were investigated. The cements were derived from a polycarboxylic acid (PCA) and a calcium phosphate cement (CPC) powder that consisted of equimolar amounts of tetracalcium phosphate (TTCP) and dicalcium phosphate (DCPA). Retardation of the setting reaction in the PCA-CPC cements was observed by adding tribasic sodium phosphate and fluorides such as stannous fluoride, zirconium(IV) fluoride and titanium(IV) fluoride. It was found that increasing the concentration of these additives decreased the mechanical strength of the cements. However, improvements in both setting and mechanical properties for the PCA-CPC cements were observed by the combined use of 8% (w/w) stannous fluoride and 10% (w/w) tartaric acid. The mechanical properties of the PCA-CPC cement also were improved by adding calcium acetate, calcium methacrylate, zirconium(IV) sulfate and phosphonoacetic acid.

Acetates↗
PubMed1993

Suppression of cytotoxic T-lymphocyte activity during human pregnancy.

We have investigated alterations in Epstein-Barr virus antigen specific cytotoxic T-lymphocyte (EBV-CTL) activity during human pregnancy. EBV-CTL activity was determined by a modified EBV induced B-cell focus regression assay and was expressed in terms of a regression index (IR50), i.e. the initial cell concentration required to achieve a 50%-incidence of regression in EBV-infected cell culture. Increased values of IR50 indicate the suppression of EBV-CTL activity. In 113 human female T-cell leukemia type-I (HTLV-I) non-carriers, the IR50 values (mean +/- S.E.) in non-pregnant, pregnant (the first trimester, second trimester and third trimester of pregnancy) and puerperal women were 10.6 +/- 1.4, 16.1 +/- 1.1 (20.1 +/- 2.0, 14.8 +/- 2.0, 14.6 +/- 1.6), and 12.1 +/- 1.9 respectively. Among HTLV-I carriers, the IR50 values (mean +/- S.E.) were likewise 34.6 +/- 8.0, 87.4 +/- 5.2 (101.7 +/- 6.3, 88.3 +/- 8.4 and 79.5 +/- 9.2) and 39.2 +/- 7.1 respectively. This data demonstrate: 1) EBV-CTL activity was suppressed during pregnancy (P < 0.05), especially in the first trimester (P = 0.0003). 2). In HTLV-I carriers, this suppression was shown in the first trimester (P = 0.0002), in the second trimester (P = 0.0002) and in the third trimester of pregnancy (P = 0.0014) and 3). One month after delivery, this suppression had returned to the non-pregnant level in both HTLV-I non-carriers and HTLV-I carriers. Pregnancy therefore has a suppressive effect on antigen specific cytotoxic T-lymphocyte activity and this effect is amplified in HTLV-I carriers.

Adult↗
PubMed1993

Chronic graft-versus-host disease with follicular involvement.

The clinical and histopathological findings in a 25-year-old Japanese male patient who suffered from chronic graft-versus-host-disease (GVHD) with follicular involvement are described. The patient had been diagnosed as aplastic anemia and underwent an allogeneic bone marrow transplant (BMT). In the eighth month thereafter, pruritic follicular red papules developed over his trunk and extremities. A biopsy specimen revealed histological exocytosis of lymphocytes into the hair follicles and basal-cell vacuolization of the follicular epithelium. Analysis of T-lymphocyte subpopulations in the dermis revealed a predominance of CD4 positive cells. To our knowledge, several cases of acute follicular GVHD have been reported; however, the occurrence of chronic GVHD with follicular involvement (chronic follicular GVHD) has not been clearly documented.

Adult↗
PubMed1993

Chemical modification by polyethylene glycol of the anti-tumor enzyme arginine deiminase from Mycoplasma arginini.

Amino acid-degrading enzymes are known to inhibit the growth of tumor cells in culture by depleting amino acids in the medium. Here we demonstrate that arginine deiminase (EC 3.5.3.6) from Mycoplasma arginini had stronger growth-inhibitory activity against all 4 kinds of tumor cell lines tested than L-asparaginase and arginase, which are well-known anti-tumor enzymes. Next, chemical modification of the arginine deiminase molecule with polyethylene glycol was shown to enhance its potency as an anti-tumor enzyme. The percentage of modified amino groups per molecule was estimated to be 51% of the total amino groups, and the average molecular weight was estimated to be about 400,000 by gel-filtration HPLC. The enzymic activity of the modified enzyme was 25.5 units/mg protein, which was equivalent to 57% of that of the native enzyme. The modified enzyme strongly inhibited growth of a mouse hepatoma cell line, MH134, at a concentration of more than 10 ng/ml, showing almost the same dose-response curve as the native enzyme. When a bolus of 5 units of the modified enzyme was intravenously injected into male BDF1 mice, L-arginine in the blood completely disappeared within 5 min, and remained undetectable for more than 8 days. On the other hand, in the case of bolus injection of the same number of units of native enzyme, the plasma L-arginine level recovered up to 66% of the control level at 8 days. These results suggest that this modified enzyme has a longer plasma clearance time and may be more effective as a new anti-tumor agent than the native enzyme.

Animals↗
PubMed1993

The transport mechanism of an organic cation, disopyramide, by brush-border membranes. Comparison between renal cortex and small intestine of the rat.

The characteristics of disopyramide uptake in brush-border membrane vesicles isolated from rat renal cortex and small intestine were investigated. Transport of disopyramide into an osmotically reactive intravesicular space was observed with notable binding to the membrane surface. An outwardly directed H+ gradient stimulated disopyramide uptake, resulting in a transient uphill transport in both brush-border membranes. As for the renal brush-border membrane, the H+ gradient itself appeared to be the driving force for this stimulation of uptake. These findings suggest that disopyramide-H+ antiport is the mechanism of disopyramide action in renal cell membrane. The initial uptake was saturable (Km and Vmax of 68.0 microM and 1.25 nmol (mg protein)-1/30 s, respectively). The stimulation of disopyramide uptake by an outward H+ gradient in rat intestinal brush-border membrane was due to an interior negative H(+)-diffusion potential. A K(+)-diffusion potential (interior negative) enhanced disopyramide uptake. These results suggest that there are different mechanisms of disopyramide uptake for renal and intestinal brush-border membrane vesicles.

Animals↗
PubMed1993

Effects of the molecular weight of hyaluronic acid and its action mechanisms on experimental joint pain in rats.

OBJECTIVES: It has been shown previously that hyaluronic acid (HA) has an analgesic action on bradykinin induced pain in the knee joints of rats. This study further clarifies the effects of the molecular weight of HA and its mechanism of action in the same model using HA of molecular weight 800 to 2.3 x 10(6) daltons and a bradykinin antagonist. METHODS: Bradykinin and the test HA preparations were given to rats by intra-articular injection, and the severity of pain was evaluated by a change in the walking behaviour. RESULTS: HA with a molecular weight greater than 40 kilodaltons produces analgesic effects with a simultaneous or earlier injection. The ID50 values of HA with molecular weight 40, 310, 860, and 2300 kilodaltons were greater than 2.5, 0.6, 0.07, and 0.06 mg/joint respectively. The duration of the analgesic effect of 860 and 2300 kilodalton HA was 72 hours at 10 mg/ml, whereas that of 310 kilodalton HA was short, being undetectable after 24 hours. The analgesic action of HA of 860 kilodaltons was not changed by pretreatment with four saccharide HA and inhibited by pretreatment with HA larger than six to eight saccharides, capable of binding to HA receptors. Further, HA did not interfere with the analgesic action of the bradykinin antagonist, indicating that HA does not directly bind with bradykinin receptors. CONCLUSIONS: HA with a molecular weight of greater than 40 kilodaltons produced an analgesic effect, and HA of 860 and 2300 kilodaltons produced high and long-lasting analgesia. These effects of HA appear to be caused by the interaction between HA and HA receptors.

Animals↗
PubMed1993

Normal uterus and FIGO stage I endometrial carcinoma: dynamic gadolinium-enhanced MR imaging.

Dynamic magnetic resonance (MR) imaging was performed on a 1.5-T superconducting unit for evaluation of 26 stage I endometrial carcinomas. To establish the appearance of the normal uterus, 27 normal uteri were also evaluated. After rapid injection of gadopentetate dimeglumine, dynamic images were obtained every 30 seconds with the spin-echo technique in the sagittal plane. On dynamic studies of endometrial carcinoma, the tumor-myometrial contrast was marked at 120 seconds after administration of gadopentetate dimeglumine (contrast-to-noise ratio [C/N], 26.0). The tumor-myometrial contrast on the dynamic study was more marked than that on postcontrast T1-weighted images (C/N, 10.0) and on T2-weighted images (C/N, 2.14). Dynamic and postcontrast MR images were superior in enabling differentiation of viable tumors from necrosis or residual secretion in the endometrial cavity. In the evaluation of presence of tumor and myometrial invasion, the accuracy of T2-weighted imaging and dynamic imaging was 67.9% and 84.9%, respectively.

Adult↗
PubMed1993

Hyperintense uterine leiomyoma at T2-weighted MR imaging: differentiation with dynamic enhanced MR imaging and clinical implications.

PURPOSE: To evaluate the role of dynamic enhanced magnetic resonance (MR) imaging in differentiating leiomyomas with high signal intensity at T2-weighted imaging. MATERIALS AND METHODS: Histologic features of 34 uterine leiomyomas that showed hyperintensity on T2-weighted images were compared with those of ordinary hypointense leiomyomas (n = 74). The results of treatment with gonadotropin-releasing hormone analogue were also analyzed in relation to pretreatment signal intensity. RESULTS: Degenerated leiomyomas (n = 13) had higher signal intensity and heterogeneous architecture, but there was considerable overlap in signal intensity with cellular leiomyomas (n = 21). At dynamic enhanced MR imaging, cellular leiomyomas had marked contrast enhancement in the early phase, while degenerated leiomyomas showed slight or irregular enhancement. Cellular leiomyomas were reduced significantly in size after treatment (P = .02). The response in degenerated leiomyomas was minimal. CONCLUSION: Evaluation of signal intensity at T2-weighted imaging and degree of contrast enhancement at dynamic enhanced MR imaging provide useful information on the nature of leiomyomas.

Buserelin↗
PubMed1993

Glomerular growth in the remnant kidney after a contralateral nephrectomy.

A unilateral nephrectomy enhances growth or weight gain in the remaining kidney, although it is not known whether the mechanism involves the division of glomerular cells. We have isolated glomeruli from the remnant kidney at different time intervals after a nephrectomy and measured the percentage of cells in the G1, G2 + M and S phases by flow cytometry. All the steady-state glomerular cells remained in G1 phase, while a significant percentage had progressed into the S phase by 4 h after the uninephrectomy. The rise in the number of cells in the S phase gradually decreased to control values by 48 h, during which time the number of cells in both G1 and G2 + M phases increased concomitantly. Neither DNA nor RNA content per glomeruli was altered by 4 and 24 h after uninephrectomy. The data suggest an early division of the glomerular cells in the remnant kidney after a contralateral nephrectomy.

Animals↗
PubMed1993

Physarum vitronectin-like protein has extensive homology to dihydrolipoamide acetyltransferase.

Physarum vitronectin-like protein with a molecular mass of 70 kDa cross-reacts with anti-bovine vitronectin and promotes cell-spreading (Miyazaki, K. et al. 1992. Exp. Cell Res., 199: 106-110.). The amino-terminal sequence of Physarum vitronectin-like protein is, however, distinct from those of animal vitronectins but shows significant sequence homology with dihydrolipoamide acetyltransferase, a component of pyruvate dehydrogenase complex. We have investigated the structural relationships between Physarum vitronectin-like protein and dihydrolipoamide acetyltransferase by using both antibody and protein-chemical methods. The vitronectin-like protein reacted with both anti-bovine vitronectin IgG and anti-rat pyruvate dehydrogenase complex IgG, indicating that it shares common antigenic determinant(s) with rat pyruvate dehydrogenase complex. Furthermore, sequencing studies of peptides obtained by lysylendopeptidase digestion indicated that internal sequences of Physarum vitronectin-like protein show significant homology with dihydrolipoamide acetyltransferase, but do not show any homology with the primary structures of authentic vitronectins. Immunocytochemistry revealed that the protein is widely localized in cytoplasm and nuclei of Physarum polycephalum, but is not present in the central area of vacuoles. Our results indicate that Physarum vitronectin-like protein is a molecule structurally and immunologically related to dihydrolipoamide acetyltransferase but functionally similar to animal vitronectin, although its localization is unique.

Acetyltransferases↗
PubMed1993

Characterization of cell-adhesive proteins secreted by cell lines growing in protein- and lipid-free synthetic medium: mouse L.P3 cells secrete a procollagen molecule with potent cell-attachment activity.

We have previously shown that mouse L.P3 cells secrete fibronectin and a novel protein, gelatin-non-binding and heparin-binding cell-adhesive protein (GNCP). Here, we screened and characterized cell-adhesive proteins in the conditioned media (CM's) of a series of cell lines growing in a protein- and lipid-free synthetic medium (P3 cell lines). Although cell-attachment activity of the CM's ranged from undetectable to highly significant, fractionation with affinity columns revealed the presence of significant cell-attachment activity in all CM's. Using cell-attachment assay and immunoassay on blotted filters, various cell-adhesive proteins were detected in the CM's, and most of them were identified as fibronectin, laminin, vitronectin, and collagen. GNCP-like proteins were detected in the CM's of HeLa.P3, JTC-16.P3, L.P3, and JTC-12.P3. There was no relationship between the origin of the cell lines and the cell-adhesive proteins secreted. GNCP purified from L.P3-CM was separated into 120-, 140-, 150-, and 160-kDa proteins on SDS-PAGE, which were judged to be a type of mouse type I procollagen from the following results: (1) they were digested by collagenase, (2) pepsin treatment converted the 150- and 160-kDa proteins into 120- and 140-kDa proteins, (3) they were recognized by anti-type I collagen antiserum, and (4) amino-terminal sequence of the pepsin-digested 140-kDa protein had significant homology with type I collagen. GNCP showed half-maximum activity of cell attachment at 0.03 micrograms/ml, indicating that GNCP was a cell-adhesive protein with an extremely high specific activity compared to other known cell-adhesive proteins.

Amino Acid Sequence↗
PubMed1993

Effects of moranoline, 4-O-alpha-D-glucopyranosylmoranoline and their N-substituted derivatives on thermostability of cyclodextrin glycosyltransferase, glucoamylase, and beta-amylase.

In repeated glycosylmoranolines synthetic reaction at 55 degrees C, cyclodextrin glycosyltransferase (CGT-ase, EC 2.4.1.19) from Bacillus stearothermophilus retained its activity for more than 600 days. A main stabilizing compound was found to be 4-O-alpha-D-glucopyranosylmoranoline. The thermostabilizing activities of moranoline, 4-O-alpha-D-glucopyranosylmoranoline, and their N-substituted derivatives were studied. Moranoline and its N-substituted derivatives stabilized glucoamylase. 4-O-alpha-D-Glucopyranosylmoranoline and its N-substituted derivatives stabilized CGT-ase and beta-amylase.

1-Deoxynojirimycin↗
PubMed1993

Changes in adenylyl cyclase activity in human endometrium during the menstrual cycle and in human decidua during pregnancy.

Adenylyl cyclase activity was studied in human endometrium during the menstrual cycle and in human decidua during pregnancy. Higher adenylyl cyclase activity was found in the endometrium than in the myometrium, corpus luteum or Fallopian tubes. In the endometrium, the basal and stimulated activities were highest in the fundus and decreased slightly from the fundus to the isthmus. Prostaglandin-stimulated adenylyl cyclase activity increased gradually from the proliferative phase to the secretory phase, and then quickly reached its highest value in the late secretory phase. Catecholamine-stimulated adenylyl cyclase activity reached a peak in the late proliferative phase and decreased significantly thereafter. Forskolin-stimulated activity was significantly higher throughout the secretory phase than in the proliferative phase. In the decidua, prostaglandin-, catecholamine- and forskolin-stimulated adenylyl cyclase activities in late pregnancy were significantly lower than those in early pregnancy. Our results demonstrate dramatic alterations in adenylyl cyclase activity in human endometrium during the menstrual cycle and in human decidua during pregnancy.

Adenylyl Cyclases↗
PubMed1993

Assessment of myometrial invasion by endometrial carcinoma: transvaginal sonography vs contrast-enhanced MR imaging.

OBJECTIVE: A prospective study was designed to compare transvaginal sonography with contrast-enhanced MR imaging to determine preoperatively the depth of myometrial invasion in patients with early-stage endometrial carcinoma. SUBJECTS AND METHODS: In 40 patients, findings on transvaginal sonograms, unenhanced T2-weighted MR images, and contrast-enhanced T1-weighted Mr images were compared with histologic findings. The depth of myometrial invasion was classified as stage E (tumor limited to endometrium, n = 12), stage S (superficial invasion: tumor invades up to 50% of the myometrium, n = 15), or stage D (deep invasion: tumor invades more than 50% of the myometrium, n = 13). RESULTS: Findings on transvaginal sonograms were accurate in 27 of 40 patients (accuracy, 68%); the depth of invasion was overestimated in five patients and underestimated in eight patients. The results of unenhanced T2-weighted MR images were accurate in 27 patients (accuracy, 68%), with four overestimations and nine underestimations. The results of contrast-enhanced T1-weighted MR images were accurate in 34 patients (accuracy, 85%), with five underestimations and one overestimation. In the assessment of each stage of myometrial invasion, the sensitivity and specificity of contrast-enhanced T1-weighted imaging were higher than those of T2-weighted MR imaging and transvaginal sonography. The false-positive diagnoses based on transvaginal sonograms and T2-weighted images, respectively, involved polypoid tumors (n = 4 and 2), distension of the endometrial cavity by pyometra (n = 2 and 1), the presence of myoma (n = 2 and 1), atrophy of the myometrium (n = 1 and 0), and poor tumor/myometrium contrast (n = 0 and 2). On contrast-enhanced MR images, accuracy was influenced only in a case of polypoid tumor, because tumor, endometrial cavity, and myometrium were clearly distinguished and residual myometrium was clearly visualized. With all imaging techniques, false-negative diagnoses were caused mainly by tumors with superficially spreading growth or microscopic invasion. With transvaginal sonography, infiltrative tumor also tended to be understaged (n = 3). CONCLUSION: Contrast-enhanced MR imaging is significantly superior to transvaginal sonography and unenhanced T2-weighted MR imaging for detecting myometrial invasion.

Adult↗
PubMed1993

[Study on semen collection from patients with anejaculation by electrostimulation].

Several methods to provoke ejaculations artificially have been used to treat patients with anejaculation. The purpose of this study is to investigate the clinical usefulness of electroejaculation for patients with anejaculation induced by spinal cord injury or surgical operation. Forty patients with spinal cord injury and one with anejaculatin after radical operation for rectal cancer underwent electroejaculation by Brindley's technique and/or modified Seager's technique. To reduce the electric energy consumed in patients, we applied bipolar pulses for modified Seager's technique instead of sine-wave current. Seminal emissions were obtained from 11 out of 18 patients by Brindley's technique and from 24 out of 29 patients by Seager's technique. From the patient with anejaculation after radical operation for rectal cancer, semen was obtained by modified Seager's technique. Most common complications were autonomic dysreflexia and pain. Since these complications disappeared soon after the termination of electrostimulation, this method was thought to be safer than intrathecal injection of neostigmine. Regarding the semen quality, it seemed that total sperm counts got worse as the interval after injury was extended. Not only in the chronic stage but also in the first one month after spinal cord injury, sperm motility was low. It was suggested that dysfunction of the testis and epididymis appeared in the early stage of spinal cord injury.

Adolescent↗
PubMed1993

The study of HCV antibody and serologic tests for syphilis in Thai patients with gynecologic disorders.

Investigation for prevalence of antibodies to hepatitis C virus (HCV) and to Treponema pallidum was conducted in 883 females with gynecologic disorders who were admitted to the gynecological ward of the Department of Obstetrics and Gynecology, Siriraj Hospital during April to August 1991. The study population consisted of 678 patients with malignancies and 205 patients with benign diseases. Anti-HCV antibody was found in 3.1% of the cases with malignancies and 1.46% of those with benign diseases. Among the gynecologic malignant group, the patients with carcinoma of cervix had the highest prevalence of HCV antibody (3.6%). The positive serologic tests for syphilis in patients with carcinoma of cervix (9.8%) were significantly higher from those in patients with ovarian carcinoma (3.75%) (p < 0.01). There were 3 cases with carcinoma of cervix who were simultaneously sero-positive for both HCV and syphilis.

Adult↗