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Biomedical subjects

S Minami

Publications and source records attributed to S Minami.

At least 19 recordsLinked to original sources
PubMed1992

Mechanical stability of the pedicle screw fixation systems for the lumbar spine.

Five different pedicle screw systems: AO Fixator Interne, VSP Steffee plate, Luque ISF, modified Zielke, and Chiba-type plate screw system (experimental device), were evaluated for biomechanical strength. A fatigue test for the screw, compressive, and torsional tests for the pedicle screw systems and a pull-out test of the pedicle screw were done. Even the Schanz screw, which showed the highest endurance limit, may be broken under the continuous loading condition in the body. The AO Fixator Interne and Steffee plate system themselves are rigid and are indicated for injuries that need reduction. The Luque ISF, modified Zielke, and Chiba-type plate screw systems, however, are indicated for degenerative lumbar disease requiring in situ fusion. There was a linear positive correlation between the bone mineral density of the vertebral body and the pull-out strength of the pedicle screw (correlation coefficient, 0.68). The fixation strength of the pedicle screw to the bone decreased remarkably in osteoporosis.

Biomechanical Phenomena↗
PubMed1992

Chiba Spinal System in the operative management of scoliosis.

The Chiba Spinal System was developed for three-dimensional correction of scoliosis. The system consists of a 7-mm diameter smooth solid rod, closed and open hooks, and specially designed conical sleeves. The rod does not have ratchets or threads, thus minimizing stress concentrations. The closed and open hooks are attached to the rod using the conical sleeves. The sleeves have longitudinal slits permitting compression during insertion. The outrigger system with a torque wrench is used to correct the deformity in the frontal plane. When correcting lordosis with vertebral rotation, a sagittal correction device may be used. Fifty-two patients with idiopathic scoliosis were operated on with this system from 1986 through 1989. The average correction of the scoliosis was 58%. For the 21 patients with thoracic lordosis less than 0 degrees, the mean preoperative lordosis was -8 degrees, which was corrected to +7 degrees. The mean correction of the vertebral rotation was 24%. Two patients complained of paresthesia of the thoracic region after operation, but this disappeared within 2 weeks. In 32 patients with more than 2 years' follow-up, the mean loss of correction was 3 degrees. One case with instrumentation failure was noted.

Adolescent↗
PubMed1992

Central administration of neuropeptide Y induces precocious puberty in female rats.

To examine the role of neuropeptide Y (NPY) in the regulation of puberty, the effects of various doses of NPY or saline injected into the 3rd ventricle of peripubertal female rats were determined. A single injection of NPY at a dose range of 10-20 micrograms into the 3rd ventricle of 30-day-old female rats advanced the time of vaginal opening (VO) and first ovulation by 4 days, as compared to saline-treated controls. Ova number and ovarian, adrenal and uterine weights at first estrous were similar in all animals regardless of treatment. The NPY-treated precocious animals showed lower body weight than did the VO-matched controls, but showed similar body weight as that of age-matched controls. Determination of plasma luteinizing hormone (LH) levels in the peripubertal female rats revealed that plasma LH was increased transiently immediately after NPY administration. Also, NPY-treated rats which had precocious puberty showed elevated pituitary and plasma LH levels on the day of VO. These results suggest that NPY can activate the hypothalamic-pituitary-gonadal axis to precociously initiate puberty.

Age Factors↗
PubMed1992

Effects of estrogen, pituitary gonadotropins and prolactin on immunohistochemical localization of inhibin subunits in the ovary of hypophysectomized female rats.

Effects of estrogen, pituitary gonadotropins and prolactin on immunohistochemical localization of alpha- and beta A-subunits in the ovaries of hypophysectomized female rats were investigated. Hypophysectomy resulted in disappearance of immunoreactive inhibin subunits in the ovary. Administration of DES, FSH and LH to hypophysectomized rats provoked growth of follicles, and resulted in positive immunostaining for inhibin subunits in the granulosa cells. In contrast to follicle-stimulating hormone (FSH) and luteinizing hormone (LH), prolactin administration failed to demonstrate positive staining for inhibin subunits in the ovary. The present in vivo results suggest that several hormones which are known to stimulate granulosa cell growth and maturation, such as estrogen, FSH and LH, enhance inhibin subunit production by the ovary. The morphologic aspect of inhibin subunit production by the ovary in response to several hormones has been demonstrated in the present study.

Animals↗
PubMed1992

Systemic administration of recombinant human growth hormone induces expression of the c-fos gene in the hypothalamic arcuate and periventricular nuclei in hypophysectomized rats.

The neuronal expression of the protooncogene c-fos could serve as a marker of neural activity. To identify the brain sites responding to GH, rat brains after systemic administration of recombinant human GH (rhGH) were processed for hybridization histochemistry for c-fos mRNA. Adult male Wistar rats were hypophysectomized 10 days before rhGH administration. After hypophysectomy, rats received sc cortisone acetate (0.5 mg/kg BW) and L-T4 (20 microgram/kg BW) daily. Four international units (1.33 mg) of rhGH were given iv through an indwelling right atrial cannula. Vehicle was administered to control animals. The rhGH treatment was accompanied by expression of the c-fos gene in the arcuate nucleus (ARC) of the hypothalamus. The accumulation of the c-fos mRNA was transient, reaching maximum values at 60 min and decreasing thereafter to reach control levels within 120 min after rhGH injection. Among control animals, c-fos gene expression was not detected in the ARC. The c-fos mRNA was also detected in the paraventricular nucleus after rhGH administration; however, it was comparable to that in control animals. When rhGH was administered twice at 40-min intervals, c-fos gene expression was induced in the periventricular nucleus (PeV) as well as the ARC 40 min after the second rhGH injection. Throughout the studies, c-fos mRNA was not detected other than in the ARC, paraventricular nucleus, and PeV in the hypothalamus. In the ARC, distribution of the cells expressing the c-fos gene appears to overlap at least in part with somatostatin (SS) mRNA-containing cells. In the PeV, it appeared to correlate generally with the distribution of SS mRNA-containing cells. The data suggest that GH feeds back on neurons of hypothalamic PeV and ARC expressing SS mRNA, and that c-fos expression is involved in the feedback mechanism.

Animals↗
PubMed1992

Expression of growth hormone (GH)-releasing factor gene in GH-producing pituitary adenoma.

Pituitary cells synthesize various neuropeptides that influence pituitary hormone secretion. GH-releasing factor (GRF) may also be produced by normal or pituitary tumor cells. We examined GRF gene expression in pituitary tumors. Standard techniques for the analysis of GRF gene expression did not appear to be suitable. Highly sensitive reverse transcription coupled to polymerase chain reaction was used. Specimens of pituitary adenoma were obtained by transsphenoidal adenomectomy from six patients with acromegaly and three patients with no clinical evidence of pituitary hormone overproduction; non-functioning adenoma. Pituitary glands were collected at autopsy from three patients who died from nonendocrine disorders. A specific GRF gene transcript was detected in five out of six GH-producing pituitary adenomas, whereas this was not found in three separate specimens of nonfunctioning pituitary adenoma or anterior and posterior pituitary tissue. The data suggest that GRF is synthesized as an intrinsic product in human GH-producing pituitary adenoma.

Acromegaly↗
PubMed1992

Immunohistochemical localization of inhibin/activin subunits in human ovarian follicles during the menstrual cycle.

The immunohistochemical localization of the alpha-, beta A-, and beta B-subunits of inhibin was examined in human follicles during follicular growth. Immunoreactive staining with antisera against the alpha-, beta B-subunits was observed in follicular granulosa cells, whereas no staining for each inhibin subunit was observed in thecal or interstitial cells. In the preantral and small antral follicles, the granulosa cells exhibited positive immunoreactive staining with antisera against beta A- and beta B-subunits and negative immunostaining with antiserum against alpha-subunit. In medium-sized healthy antral follicles obtained during the midfollicular phase, positive immunostaining with antisera against alpha-, beta B-subunits was detected in the granulosa cells. In contrast, immunostaining for alpha-, beta A-, and beta B-subunits was not detected in the granulosa cells of similarly sized atretic follicles. The granulosa cells of preovulatory follicles revealed enhanced positive staining for the three inhibin subunits. The present findings suggest that immunoreactive inhibin subunits are present in the follicular granulosa cells during the menstrual cycle, and that the localization and intensity of immunostaining for each inhibin subunit might change during follicular development and maturation.

Activins↗
PubMed1992

A point mutation in the 3,5,3'-triiodothyronine-binding domain of thyroid hormone receptor-beta associated with a family with generalized resistance to thyroid hormone.

A tight linkage between generalized resistance to thyroid hormone (GRTH) and the thyroid hormone receptor-beta (TR beta) gene is indicated. We evaluated a family with GRTH for the TR beta gene. We found that a new point mutation, consisting of a cytosine to adenine replacement at nucleotide position 1642, resulted in substitution in codon 448 in the T3-binding domain of TR beta. This base substitution was found in only one allele of affected members, but not in unaffected members of the family. The in vitro translation products of this mutant TR beta gene demonstrated significantly reduced T3-binding affinity. Previously, others have reported a kindred with GRTH, in that the same codon was subjected to proline to histidine replacement due to a mutation consisting of a cytosine to adenine replacement at nucleotide position 1643. There appeared to be a significant phenotypic difference between our kindred and that described by others.

Alleles↗
PubMed1992

Transforming growth factor-beta 1 messenger RNA and protein expression in the pituitary gland: its action on prolactin secretion and lactotropic growth.

Transforming growth factor-beta 1 (TGF-beta 1) is known to inhibit cell growth and proliferation of many estrogen-responsive normal and transformed cells. The effect of this polypeptide growth factor on the estrogen-responsive pituitary lactotropes has not been determined. To evaluate the role of TGF-beta 1 in the control of lactotropic growth, the action and production of TGF-beta 1 in the anterior pituitary was studied in rats. The growth factor suppressed basal PRL release from the primary culture of enriched rat lactotropes in a concentration-dependent manner in the range of 2 pg/ml-20 ng/ml. The growth factor did not affect the secretion of other pituitary hormones in the cultures. The inhibitory action of TGF-beta 1 on PRL release was time dependent. The minimum time required to produce a significant effect was 4 h. The growth factor also suppressed estradiol-induced PRL release as well as it inhibited estradiol-induced proliferation of lactotropes. TGF-beta 1 immunoreactivity was detected in the cellular extracts of cultured anterior pituitary cells and in the extracts of anterior pituitary tissue. In addition, the primary culture of enriched rat lactotropes secreted TGF-beta 1. Using Northern blot techniques, a 2.4-kilobase transcript of pro-TGF-beta 1 mRNA was detected both in the anterior pituitary tissue and in the primary culture of anterior pituitary cells. These data suggest that TGF-beta 1 is produced in the pituitary gland and inhibits the secretion of PRL and growth of lactotropes in an autocrine and/or paracrine fashion.

Animals↗
PubMed1992

An endoscopic study of antibiotic-associated hemorrhagic colitis.

Colonoscopy was performed on acute stage within 72 hours from onset in 48 patients with antibiotic-associated hemorrhagic colitis (AAHC). From our observations we have developed a new endoscopic classification of AAHC and investigated the incidence of each finding in further detail. We have classified in principle the endoscopic findings of the 48 subjects into two groups: major and minor ones respectively. Category of major findings were: 1) diffuse mucosal hemorrhage (100%); 2) spotty mucosal hemorrhage (100%), and 3) linear mucosal hemorrhage (22.9%), while minor findings were: 1) irregular ulcers in 10.4%; 2) aphthoid ulcers in 6.3%, and 3) linear erosions or ulcers in 4%. Minor findings were ulcers or erosions present over the hemorrhagic mucosa associated with the moderate degree of inflammation. A histopathologic study of colon biopsy specimens from 24 patients with AAHC showed hemorrhage and inflammatory cell infiltration in the lamina propria mucosae varying from mild to moderate in extent. It was concluded that AAHC was a colonic mucosal hemorrhagic disease caused by the destruction of mucosal vessels from unknown causes and in this disease mild to moderate inflammation was partially followed by ulceration over the edematous and hemorrhagic mucosa of the colon.

Adolescent↗
PubMed1992

Frequency thresholds of rat cochlear nerve fibers.

Activities of single cochlear nerve fibers of Wistar rats were recorded extracellularly. Best frequencies (BF) distributed from 0.50 to 62.6 kHz. The audiogram was made as the minimum boundary of the BF threshold distribution. The range of audible frequency was 0.54-63 kHz at 60 dB SPL and 0.15-67 kHz at 100 dB SPL. The lowest trough of the audiogram was 5 dB SPL at 41.2 kHz. There was the second trough of 10 dB SPL at 7.01 kHz leaving a notch between the two troughs. The shapes of the frequency-threshold curves (FTCs) of fibers were evaluated quantitatively and typical FTCs were shown as a function of BF.

Acoustic Stimulation↗
PubMed1992

Immunohistochemical localization of inhibin/activin subunits in human placenta.

OBJECTIVE: To examine the cellular localization of each inhibin subunit in human placenta throughout pregnancy. METHOD: Placental tissues were collected and fixed in Bouin's solution, and studied with the immunohistochemical technique avidin-biotin-peroxidase complex. RESULTS: There was immunohistochemical staining with antisera against each inhibin subunit in the syncytiotrophoblast, but not in the cytotrophoblast. In the first-trimester placenta, positive immunostaining for alpha- and beta A-subunits was clearly observed in the syncytial layer of villi, whereas staining for beta B-subunit was faint. In the second-trimester placenta, the relative intensities of staining for alpha- and beta A-subunits were similar to those in the first-trimester placenta, and enhanced positive immunostaining with beta B-subunit antiserum was observed. The relative amount of immunostainable alpha-subunit declined within the syncytiotrophoblast of the third-trimester placenta, whereas levels of immunostainable beta-subunits were unchanged. CONCLUSIONS: Inhibin subunits may be produced in the syncytiotrophoblast throughout pregnancy, and activin as well as inhibin may be synthesized in the syncytiotrophoblast of the term placenta.

Activins↗
PubMed1992

Bone marrow transplantation for chronic myelogenous leukemia in blastic phase using a phenotypically identical unrelated volunteer donor. Nagoya Bone Marrow Transplantation Group (NBMTG), Tokai Marrow Donor Bank (TMDB).

A 26-year-old male with chronic myelogenous leukemia in lymphoid blast crisis received a bone marrow transplant (BMT) from a phenotypically identical, mixed lymphocyte reaction (MLR)-weakly positive unrelated male volunteer donor. The volunteer was obtained from the Tokai Marrow Donor Bank (TMDB), which was established in Japan in 1989. This donor was selected from volunteer donors who were identical with our patient at the HLA-A,B loci, followed by matching at HLA-DQ, DR loci. On MLR testing, the donor's cells showed no response, but the patient's cells showed a low response to the donor's cells (relative response index 0.29). The patient showed rapid hemopoietic engraftment. He developed acute graft-versus-host disease (GVHD) with vesicle formation on palms and soles and mild liver damage, which were successfully treated with intravenous prednisolone 1 mg/kg per day. Although he also suffered from interstitial pneumonitis on day 64 and localized varicella-zoster infection on day 87, and has suffered from moderate stomatitis and dry skin characteristic of chronic GVHD, he is currently 22 months post-transplant with hematological remission and has a normal daily social life.

Adult↗
PubMed1992

[Treatment of aplastic anemia with antilymphocyte globulin, high-dose methylprednisolone and androgen].

Twenty-seven patients with aplastic anemia (20 severe: 7 moderate) were treated with combined immunosuppression consisting of antilymphocyte globulin (ALG: Ahlbulin, Green Cross Co., Osaka, Japan) and high-dose methylprednisolone. Danazol or meptiostane was administered concurrently for at least 3 months. Ten of 27 patients had sustained improvement in hematopoiesis within 3 months of treatment. Three patients with hematological response had a recurrence of pancytopenia 12-36 months after the combined immunosuppressive therapy. Six patients died due to fungal pneumonia (2), hepatic failure (2), interstitial pneumonitis (1) and complication following allogeneic bone marrow transplantation (1). By life table analysis, the survival rate for all patients was 76 +/- 8% at 4 years, with 70 +/- 10% survival rate for patients with severe aplastic anemia and 100% for patients with moderate aplastic anemia. The factors predicting the good response to the therapy were a longer interval from diagnosis to the therapy and higher counts of platelet and reticulocyte at admission.

Adolescent↗
PubMed1992

[A case report of multiple-transfused aplastic anemia complicated by hemolysis and delayed neutrophil recovery after bone marrow transplantation].

The authors report an 18-year-old female who developed severe hemolytic reaction and delayed neutrophil recovery after bone marrow transplantation (BMT) for aplastic anemia from her HLA-identical sibling. She had received much transfusion (61 units of red blood cells including 4 units of fresh whole blood from her parents and 350 units of platelets) for 12 years before BMT. To prevent graft rejection, she received an intensified preparative regimen consisted of cyclophosphamide 200 mg/kg followed by 5 Gy total body irradiation and 5 Gy total lymphoid irradiation. Prophylaxis for GVHD was short term methotrexate and cyclosporin-A. Despite of the removal of the red cells from the marrow, marked hemolytic reaction caused by antibodies directed to rh" (E) and hr' (c) red cell antigens was observed when rh" (E) and hr' (c) positive donor erythroid began to recover. The recovery of neutrophils, especially the fraction of segmented cells was also delayed. Flow cytometry showed that the serially collected patient's sera reacted to neutrophils derived from both patient's blood on the 64th post-transplant day and the donor's blood. The reactivity was strongest in pre-BMT sera. We conclude that residual antibodies sensitized before BMT are a major cause of these hematological problems.

Adolescent↗
PubMed1991

The time-space correlation method for measurement of erythrocyte velocity in microvessels using a CCD linear image sensor.

A new method for measuring erythrocyte velocity in the microvascular system was developed. A correlation function varying both time and distance, "time-space correlation method," was used in order to improve the time correlation and the space correlation methods. A CCD linear image sensor installed at the center of the focal plane of a camera was used to convert the passage of erythrocytes through the microvascular system to electrical signals via intravital microscopy. The method was applied to small vessels in the mesentery of rats. Using the present method, the time required for the measurement and the length of the vessel necessary for the measurement have been reduced, as compared with other methods.

Algorithms↗
PubMed1991

Alternating current induced otoacoustic emissions in the guinea pig.

Injection of alternating current (AC) into the scala media of the guinea pig cochlea induced otoacoustic emissions (OAEs) at the frequency of the AC fundamental, together with harmonic and intermodulation distortion products. Although the waveform of the injected ACs was distorted, probably due to nonlinear polarization of the metal electrodes, and was composed of the fundamental plus distortion products of every order, only a few of the lowest order distortion products were selectively emitted with the fundamental. AC injection at a basal site extended the high frequency limit of OAEs. Electrical stimulation of the crossed olivocochlear bundle inhibited the sideband emissions with little change in the fundamental. OAE was reduced reversibly by temporary impairment of the cochlea due to exposure to fatiguing sound, by intravenous application of furosemide and by temporary anoxia. Irreversible reduction resulted from intracochlear perfusion with excess K+ solution, acoustic trauma and cardiac arrest. These facts imply that AC-induced OAE is not an artifact generated electrically; rather, such emissions originate in the cochlea and normal metabolic activity in the cochlea is essential. A proposed mechanism of generation includes two components: 1) electromechanical transduction from AC to mechanical vibration in the cochlea and 2) a distortion-producing process; the contribution of each component to the receptor mechanism is discussed.

Acoustics↗