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Biomedical subjects

K Takakura

Publications and source records attributed to K Takakura.

At least 199 records · Page 11Linked to original sources
PubMed1993

Temporal profile and significance of metabolic failure and trophic changes in the canine cerebral arteries during chronic vasospasm after subarachnoid hemorrhage.

To investigate the pathogenetic significance of metabolic failure observed in spastic cerebral arteries after subarachnoid hemorrhage (SAH), the temporal profile of alterations in the arterial content of high-energy phosphates was studied. A canine model of double hemorrhage was used. Constriction of the basilar artery was measured angiographically on Days 3, 5, 7, and 14 after SAH in separate groups of animals. Adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), guanosine triphosphate (GTP), guanosine diphosphate, creatine phosphate (CrP), and creatine (Cr) levels in the arteries were assayed using high-performance liquid chromatography. A time-dependent development of angiographic spasm was confirmed. A mild vasospasm was seen in the group studied 3 days after SAH, progressed in the Day 5 group, remained comparably severe in the Day 7 group, and resolved partially in the Day 14 group. The content of high-energy phosphates (ATP, GTP, and CrP) declined rapidly over the course of the study, and a significant reduction in ATP, GTP, and CrP was observed in the Day 3 group. Levels of ATP and CrP decreased further in the Day 5 and 7 groups. The decrement in GTP was completed in the early phase; a significant reduction took place in the Day 3 group, with no progression thereafter and no recovery through Day 14. Total adenylate (ATP + ADP + AMP) and total creatine (Cr + CrP) content diminished markedly over the course of the study. These results indicate that metabolic failure and trophic disturbance in the cerebral artery occurs with a rapid onset following SAH and progresses in close association with the development of vasospasm, suggesting a significant causal relationship with the pathogenesis.

Adenosine Triphosphate↗
PubMed1993

Immunohistochemical study of craniopharyngiomas.

The purpose of this study is to present the histological characteristics of tumor origin and proliferative characteristics of craniopharyngioma. In 25 craniopharyngiomas, the immunoperoxidase technique revealed strong positive reactions for keratin and cytokeratin in cytoplasm of tumor cells. But, immunostaining of keratin and cytokeratin differ from each of layer of craniopharyngioma. The ciliated epithelium in the craniopharyngioma was not stained by keratin, but ciliated epithelium of Rathke's cleft cyst was stained by cytokeratin.

Antigens, Neoplasm↗
PubMed1993

[Two cases of giant aneurysms arising from the distal segment of the anterior cerebral circulation].

Giant aneurysm arising from the distal segment of the anterior cerebral circulation is extremely rare, and only 14 cases of anterior cerebral circulation aneurysms have been reported in the literature. This report describes two cases of giant intracranial aneurysms, one arising from the distal segment of the middle cerebral artery, and the other from the azygos anterior cerebral artery. Although both of the patients started with intracranial hemorrhage, their surgical outcomes were good. The growth mechanisms of each aneurysm are discussed based on the clinical and pathological findings. Since the wall of the middle cerebral artery aneurysm showed granulomatous changes with infiltration of many inflammatory cells, the aneurysmal enlargement is considered to have resulted from chronic inflammation of the wall. In the case of anterior cerebral artery aneurysm, hemodynamic stress through the azygos artery may have caused the giant aneurysm. Operative indication for giant intracranial aneurysm is controversial. Since the surgical outcomes of reported cases are definitely better than those of the patients with proximal giant aneurysm, we conclude that giant aneurysm arising from the distal segment of the cerebral artery should be treated surgically.

Adult↗
PubMed1993

[The microcirculatory dynamics of prostaglandin E1 and/or nicardipine and their different reactions in the hyper- and hypodynamic state of septic shock in a rat model].

The reactions of the mesenteric microcirculation dynamics to prostaglandin E1(PGE1) and nicardipine were investigated under continuous biomicroscopy with a high speed video analyzer in septic shock models using rats. Both of the drugs induced similar reactions. In the hyperdynamic state, the vasodilation and increasing velocity of red blood cells (RBC) stimulated by both of these vasodilators were similar to those in normal control state. However, in the hypodynamic state the vasodilators especially PGE1 had little effect on increasing the velocity of RBC in spite of their vasodilating action. Therefore these vasodilators are useful in order to improve the microcirculatory blood flow in states such as early septic-shock state.

Alprostadil↗
PubMed1992

Identification of 7 alpha-hydroxy-3-oxo-4-cholestenoic acid in chronic subdural hematoma.

We detected a novel kind of bile acid in the content of chronic subdural hematoma. This substance was specifically found in chronic subdural hematoma, and not in subdural hygroma, which is pathologically similar except for the lack of capsular membrane. The compound was identified as 7 alpha-hydroxy-3-oxo-4-cholestenoic acid by high performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectrometry. The structure was confirmed by the comparison with the chemically synthesized compound. The average contents in chronic subdural hematoma were 658.09 +/- 137.53 ng/ml, while those in normal human plasma were 126.27 +/- 17.73 ng/ml. It was not detected in normal cerebrospinal fluid. The higher level in chronic subdural hematoma than human plasma strongly suggests the local, extrahepatic production of this type of C27 bile acids.

Bile Acids and Salts↗
PubMed1992

Application of superfine fiberscope for endovasculoscopy, ventriculoscopy, and myeloscopy.

In the past three years, we have used a superfine fiberscope for endovasculoscopy, ventriculoscopy, and myeloscopy. Flexible superfine fiberscope, 0.75 mm in outer diameter, could visualize various intravascular findings. In in-vivo canine experiment, sequential changes of thrombus produced by endothelial abrasion by needle or balloon in the canine carotid artery can be clearly seen. And thrombolysis by focal arterial injection of tissue plasminogen activator was sequentially observed. In the clinical study, we could evaluate the stenotic lesions of the subclavian and vertebral arteries before and after balloon angioplasty. During ventriculoscopy, a 2 mm of mini-caliber fiberscope was introduced under ultrasound monitoring, and provided clear visualization of intraventricular tumours. In myeloscopy, draining veins of arteriovenous malformations and nerve roots of the cauda equina could be clearly seen by flexible fiberscope. From these results, it can be said that the superfine fiberscope provides clear and useful visualizations of the interior of vessels, ventricles, and the intrathecal area of the spinal canal. The new applications of this superfine fiberscope for minimally invasive neurosurgery may bring about a marked improvement of therapeutic results.

Animals↗
PubMed1992

Inverse dose-rate effect of DNA breaks and inactivation of transforming activity induced by tritiated water and 60Co gamma-rays.

When an aqueous solution of plasmid DNA at a constant low concentration of 5 micrograms/cm3 was irradiated with 60Co gamma-rays, D37 dose of single-strand breaks was decreased from 18 Gy at a dose-rate of 6.77 Gy/h of acute irradiation to 2.3 Gy at a dose-rate of 0.00212 Gy/h. Or G value was increased from 0.0010 to 0.0081. Similar dose-rate dependency of D37 dose and G value were also found when the plasmid DNA solution was treated with various concentrations of tritiated water at various dose-rates, ranging from 5.13 Gy/h to 0.000118 Gy/h. RBE of tritium beta-rays for single-strand breaks was ranged from 0.3 to 0.5 in a wide range of dose-rates. When the DNA solution was saturated with argon to remove oxygen, the dose-rate dependency of gamma-rays was abolished and that of tritium beta-rays was significantly suppressed. When the DNA solution in air was kept at 4 degrees C for 50 h or 25 days after acute irradiation, the G value of DNA breaks was the same as that kept at -20 degrees C for the same period, but much lower than that of the solution irradiated for the same period at a lower dose-rate to give the same total doses. This shows that the inverse dose-rate effect could not be induced from the different exposure periods but from continuous irradiation of different dose-rates. The inverse dose-rate effect for inactivation of transforming activity of DNA irradiated with tritiated water was also observed in the range from 0.0588 Gy/h to 0.00118 Gy/h.

Cobalt Radioisotopes↗
PubMed1992

Chondrosarcoma of the skull base: report of six cases.

Five patients with chondrosarcoma, grade I or II, and one with mesenchymal chondrosarcoma of the skull base were treated at our clinic between 1967 and 1991. The patients were three men and three women who ranged in age from 21 to 39 years. The presenting symptoms were diplopia, decreased visual acuity, or symptoms of involvement of VIIIth and lower cranial nerves. The duration of the symptoms ranged from 18 months to 14 years. A plain skull x-ray and tomography of the skull, computed tomographic (CT) scans, and magnetic resonance images (MRI) revealed a calcified mass. Angiograms showed an occlusion of the arteries or venous sinuses, or both, in four patients, and a distinct tumor stain in one. The tumors were subtotally removed in all six cases. Two patients received postoperative irradiation for the residual tumor. In one patient, extraocular movement was compromised postoperatively, although in the other five patients there was no aggravation of the neurologic signs. Follow-up CT scans and MRI demonstrated no recurrent tumors nor any enlargement of residual tumors. Based on these findings, we advocate aggressive surgical removal of these tumors, which should be augmented by radiation therapy if the postoperative CT scans or MRI reveal residual tumors.

Journal Article↗
PubMed1992

Immunohistochemical localization of androgen receptor in the human endometrium, decidua, placenta and pathological conditions of the endometrium.

The immunohistochemical localization of the androgen receptor in the human endometrium at various stages of the menstrual cycle and post-menopausal period, in decidua and placenta of early pregnancy, and in several pathological conditions of the endometrium has been investigated. At any phase of the menstrual cycle, both endometrial glandular cells and endometrial stromal cells showed positive nuclear staining. Endometrial stromal cells of the functional layer showed stronger staining than those of the basal layer, but endometrial glandular cells of both layers showed the same staining intensity. There was little staining in myometrium. Even after menopause, endometrial glandular and stromal cells showed the same staining pattern as the basal layer of pre-menopausal endometrium and the staining intensity of endometrial stromal cells was weak. In decidua and placenta of early pregnancy, decidual and trophoblastic cells showed positive staining and there was no staining in the stromal cells of placenta. The expression of the androgen receptor was also detected in adenomyosis, endometriosis and endometrial carcinoma. Although the proliferation and differentiation of endometrium are mediated mainly by oestrogen and progesterone receptors, the androgen receptor may play some role in modulating these changes. These results suggest that it may be involved in both physiological and pathological changes of the endometrium.

Adult↗
PubMed1992

Immunohistochemical localization of androgen receptor in the human ovary throughout the menstrual cycle in relation to oestrogen and progesterone receptor expression.

In order to elucidate the role of androgen receptors (AR) in human ovaries, we examined their immunohistochemical localization, in comparison with oestrogen receptors (ER) and progesterone receptors (PR), at various stages of the menstrual cycle and follicular development. Primordial and primary follicles did not express AR. In granulosa and thecal cells of secondary follicles there was weak nuclear staining for AR. Granulosa cells of dominant follicles showed moderate nuclear staining for AR, which was stronger than that in thecal cells. In the luteal phase, the staining intensity for AR was strongest in the early luteal phase just after ovulation and declined gradually thereafter. Thecal cells of atretic follicles showed moderate nuclear staining for AR, which was a little stronger than that in dominant follicles. There was weak nuclear staining for AR in stromal cells surrounding follicles. Though there was variation in the staining intensity, AR were present at almost all stages of the menstrual cycle. There is a possibility that androgens, mediated by AR, may play an essential role in follicular growth and maturation, atresia and luteinization as autocrine or paracrine agents.

Adult↗
PubMed1992

Dipeptidyl peptidase IV as a differentiation marker of the human endometrial glandular cells.

To investigate the involvement of membrane-bound peptidases in the human endometrial function, we examined the expression of dipeptidyl peptidase (DPP) IV and its enzyme activity. Immunohistological studies revealed that DPP IV was detected on human endometrial glandular cells and endometrial surface epithelium, but not on endometrial stromal cells or decidual cells in the first trimester of pregnancy. DPP IV expression on glandular cells and surface epithelium was weak in the proliferative phase, began to increase gradually in the early secretory phase, and was strong in mid-to late secretory phase and in the first trimester of pregnancy. DPP IV enzyme activity was detected histochemically in glandular cells and surface epithelium in the mid-secretory phase, and became stronger in the late secretory phase, but was rarely detected in the proliferative phase and early secretory phase. During the first trimester of pregnancy DPP IV enzyme activity in glandular cells and surface epithelium was slightly weaker than in the late secretory phase. Endometrial stromal cells and decidual cells, however, had no detectable DPP IV enzyme activity at any time throughout the menstrual cycle or during the first trimester of pregnancy. These findings indicate that DPP IV is a differentiation marker for glandular cells and surface epithelium and that active DPP IV is present in both areas during the peri-implantation period and thereafter.

Adult↗
PubMed1992

Expression of aminopeptidase N and neutral endopeptidase on the endometrial stromal cells in endometriosis and adenomyosis.

Indirect immunofluorescence staining revealed that endometrial stromal cells (ESC) in the ectopic endometrium of patients with endometriosis or adenomyosis expressed aminopeptidase N/cluster of differentiation (CD) 13 antigen and neutral endopeptidase/CD10 antigen, both of which are expressed on ESC in the normal endometrium throughout the menstrual cycle. Thus, ESC in the ectopic endometrium resembled ESC in the normal endometrium not only morphologically but also antigenically. Both peptidase antigens may be useful markers for the histological diagnosis of endometriosis and adenomyosis.

Adult↗
PubMed1992

Human endometrial stromal cells and decidual cells express cluster of differentiation (CD) 13 antigen/aminopeptidase N and CD10 antigen/neutral endopeptidase.

With specific monoclonal antibodies, we found that human endometrial stromal cells and decidual cells express two function-related surface antigens. Indirect immunofluorescence staining revealed that both endometrial stromal cells and decidual cells during the first trimester of pregnancy expressed cluster of differentiation (CD) 13 antigen and CD10 antigen, which are identical to aminopeptidase N and neutral endopeptidase, respectively. By flow cytometric analysis, CD13 antigen was detected on 82-93% of the examined cells, and CD10 antigen was detected on 75-93% of the examined cells in endometrial stromal cell-enriched preparations. Furthermore, peptidase activity was detected in these cell preparations by an assay based on the hydrolysis of alanine-p-nitroanilide into p-nitroaniline and alanine.

Adult↗
PubMed1992

Expression of c-kit protein during placental development.

The c-kit proto-oncogene encodes a transmembrane tyrosine kinase receptor and is shown to be allelic with the white-spotting locus (W) of the mouse. In order to elucidate the role of c-kit protein during placental development, we have examined the expression of c-kit protein in the uterus and placenta of mice at pre- and post-implantation stages by the avidin-biotin-peroxidase (ABC) method using rat anti-mouse c-kit monoclonal antibody. At Days 3 and 5 of pregnancy and pseudo-pregnancy, c-kit protein was detected in the glandular epithelium, but little expression was observed in the luminal epithelium. At Day 7 of pregnancy, expression was detected in the stromal cells around the uterine crypts of the mesometrial portion, but not in the vigorously proliferating decidual cells around the developing embryo. At Days 9 and 10 of pregnancy, the decidua basalis facing invading trophoblasts gradually expressed c-kit protein. In the mature placenta, c-kit protein was detected in the labyrinthine and decidual layers, but in neither the giant trophoblastic nor the spongiotrophoblastic layer. By Northern blotting and reverse transcriptase-polymerase chain reaction (RT-PCR), c-kit mRNA was detected at the stages of periimplantation and placental development. These results suggested that the c-kit protein might be involved in the proliferation and differentiation of placenta.

Animals↗
PubMed1992

Differential expression of aminopeptidase-N on human ovarian granulosa and theca cells.

The expression of aminopeptidase-N and neutral endopeptidase in human ovarian tissue was examined using specific monoclonal antibodies for each of these peptidases and histochemical staining for enzyme activity. Aminopeptidase-N is a membrane-bound metalloprotease catalyzing the removal of N-terminal amino acids from peptides and was detected by immunofluorescence staining on theca interna cells in secondary follicles and on luteinized thecal cells in preovulatory follicles and corpora lutea. However, aminopeptidase-N was not detected on granulosa cells. Peptidase activity was also detected by histochemical staining on theca interna cells and luteinized thecal cells. Luteinized granulosa cells showed peptidase activity, despite the lack of aminopeptidase-N. Neutral endopeptidase was not detected in ovarian granulosa and thecal cells. These observations indicate that aminopeptidase-N can be a useful surface marker for thecal cells.

Adult↗
PubMed1992

Cytokine modulation of progesterone and estradiol secretion in cultures of luteinized human granulosa cells.

To clarify the possible roles of cytokines in the regulation of luteal cell function, we examined the effects of interferon (IFN), interleukin-1 (IL-1), and tumor necrosis factor (TNF) on progesterone and estradiol secretion in cultures of luteinized human granulosa cells. IFN gamma reduced hCG-stimulated progesterone secretion in a concentration-dependent manner; at its maximal inhibitory concentration (10 ng/mL), IFN gamma reduced progesterone secretion to 20% of that in the hCG-stimulated controls. Whereas other IFN (alpha and beta) reproduced the inhibitory effect of IFN gamma, IL-1 and TNF had no effect on hCG-stimulated progesterone secretion at concentrations of 1 and 10 ng/mL. IFN gamma also markedly reduced FSH-stimulated estradiol secretion. Unlike their effects on hCG-stimulated progesterone secretion, IL-1 and TNF reproduced the inhibitory effect of IFN gamma on FSH-stimulated estradiol secretion. IFN gamma significantly reduced both hCG- and FSH-stimulated cAMP generation in granulosa cells. IL-1 and TNF inhibited FSH-stimulated cAMP generation, but they did not inhibit hCG-stimulated cAMP generation. None of these cytokines reduced forskolin-stimulated cAMP generation, thus suggesting that these cytokines affect steps proximal to cAMP generation without affecting cAMP generation itself. IFN gamma also reduced progesterone secretion in response to (Bu)2cAMP, suggesting that it also affects steps distal to cAMP generation. This study has demonstrated that cytokines modulate the steroidogenesis of luteinized human granulosa cells in vitro; the results suggest that cytokines may play permissive roles in regulating luteal cell function.

Adult↗