Biomedical subjects

H Kurihara

Publications and source records attributed to H Kurihara.

At least 307 records · Page 17Linked to original sources

PubMed1990

Adjunctive treatment for recurrent childhood ependymoma of the IV ventricle: chemotherapy with CDDP and MCNU.

The prognosis of recurrent IV-ventricle ependymoma in children is poor. Three cases of recurrent ependymoma were treated with combination chemotherapy using cis-diamine dichloro platinum (II) (CDDP) and methyl-6-(3-(2-chloroethyl)-3-nitrosoureido)-6-deoxy-alpha-D-glucopyrano side (MCNU). The patients were 2-, 3-, and 6-year-old boys. The interval between the first operation with irradiation and recurrence was 1 year and 5 months to 2 years. Two cases showed a recurrence at the original site; in the other case, a right sylvian tumor deposit was found via computed tomography. The therapeutic regiment for recurrent ependymomas was as follows: (1) the tumor was debulked if possible; (2) additional local irradiation of 30 Gy was administered; (3) combined treatment of 100 mg/m2 CDDP and 80 mg/m2 MCNU over 24 h was given 5 times with an interval of 6 weeks between treatments. The patients tolerated the therapy well with only mild side effects. Remission lasted 1 year in two patients and has lasted for 8 months in one.

Antineoplastic Agents↗

PubMed1990

Monoclonal antibodies to endothelin: application for sandwich immunoassays.

We established 16 monoclonal antibodies (MAbs) to endothelin (ET), a novel and potent vasoconstrictor. They were classified into two groups: eight of them reacted with the C-terminal portion of ET, and the other eight reacted with the non-C-terminal portion. We constructed the sandwich enzyme linked immunosorbent assays (ELISAs) using a combination of a MAb belonging to the former with that belonging to the latter, and could detect about 400 pg/ml of ET.

Animals↗

PubMed1990

Cytoplasmic calcium ion elevating factor(s) in spontaneously hypertensive rat serum.

We have attempted to characterize the as yet unspecified circulating factor(s) in spontaneously hypertensive rat (SHR) serum that elevate(s) the cytoplasmic calcium ion concentration in vascular smooth muscle cells (VSMC). We measured the cytoplasmic calcium ion concentration in cultured VSMC before and after incubation with serum from SHR or Wistar-Kyoto rats (WKY). Incubation with serum from overtly hypertensive 8-week-old SHR, but not with serum from 8-week-old WKY, significantly elevated the cytoplasmic calcium ion concentration in VSMC from 8-week-old WKY and 4-week-old SHR in a dose- and an incubation period-dependent manner, although no significant elevation occurred in VSMC from 4-week-old WKY. Neither the heat-immobilized nor the trypsinized 8-week-old SHR serum elevated the cytoplasmic calcium ion concentration. Ultrafiltration procedures indicated that the molecular weight of the factor should be 10,000-30,000 daltons. Incubation with serum from 4-week-old SHR or WKY did not elevate the cytoplasmic calcium ion concentration. These results strongly suggest that: (1) a cytoplasmic calcium ion concentration elevating factor exists in serum from 8-week-old SHR but not from 4-week-old SHR, or 4- or 8-week-old WKY; (2) this factor should be of a protein nature, with a molecular weight of 10,000-30,000 daltons; (3) responsiveness to the factor appears in VSMC at a younger age in SHR than in WKY; (4) the factor elevates the cytoplasmic calcium ion concentration to the level determined a priori not by the strain but by the age of the rats from which the VSMC originate; and (5) the a priori determined level increases with the age of the rats.

Animals↗

PubMed1990

Disruption of microtubules as an early sign of irreversible ischemic injury. Immunohistochemical study of in situ canine hearts.

Structural disruption of the cytoskeleton may be involved in irreversible ischemic injury. In the present study, ischemic changes in microtubules during various periods of myocardial ischemia were studied with an immunohistochemical technique in open-chest dogs. In intact myocardium, microtubules were stained as a filamentous network throughout cytoplasm and a circular network around the nucleus, which disappeared with colchicine treatment. In brief ischemia of less than 15 minutes, microtubule patterns were unaltered. After 20 minutes, however, characteristic microtubule stains were partly lost in patchy lesions. As an increase in ischemic period, lesions of loss of microtubule stains were increased in number and size. After 120 minutes of reperfusion following 60 minutes of ischemia, the lesions with intact actin filaments but with disrupted microtubules were replaced by the severely injured cells in which the regular myofibrillar registrations were distinctly disrupted. After 24 hours of reperfusion following 40 minutes of occlusion of the left circumflex artery, the percent area of disrupted microtubules at 40 minutes of ischemia was replaced by that of irreversibly injured lesions in the posterior papillary muscle. These results indicate that disruption of microtubules during ischemia heralds irreversible ischemic injury. However, in in vitro study, the myocardium incubated in hypoxic solution for 60-120 minutes demonstrated earlier disruption of the microtubules than the vinculin. Electron microscopic study also showed minimal irreversible changes in the lesions with disrupted microtubules. Thus, taken together, we conclude that microtubules that support the structural integration of myofibrils and other organelles are disrupted in severe myocardial ischemia before the irreversible injury, promoting the irreversible change after reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Early changes in fine structures of the aortic arch in hamsters fed a high cholesterol diet.

Intimal changes at the prelesional stage of atherosclerotic lesions were investigated ultrastructurally using hamsters fed a high cholesterol diet for 1 day to 1 month. Observations were restricted to the lesion-prone area in the aortic arch. The endothelial cells began to show well-developed rough endoplasmic reticulum and Golgi apparatus after a few days of the cholesterol diet. After three days, macrophages which contained a few lipid droplets were observed just below the endothelium. We found that the intimal smooth muscle cell formed a gap junction with the process of the medial smooth muscle cell. After a few weeks to 1 month on the diet, the intima became markedly thickened and filled with dense extracellular matrices. The intimal smooth muscle cells showed well-developed rough endoplasmic reticulum and Golgi apparatus with immature granules, suggestive of high secretory activity. The present study showed that endothelial ultrastructural changes, macrophage invasion, and medial smooth muscle cell migration are very early events occurring within a few days after cholesterol intake commences.

Animals↗

PubMed1990

A family study of a mother and daughter with increased susceptibility to early-onset periodontitis: microbiological, immunological, host defensive, and genetic analyses.

Microbiological, immunological, host-defensive, and genetic analyses were performed on a mother and daughter, both of whom had early-onset periodontitis (rapidly progressive periodontitis in the mother; localized juvenile periodontitis in the daughter). Microscopic examination revealed a greatly elevated percentage of rod-form bacteria in both subjects. Fusobacterium sp. and Porphyromonas gingivalis (formerly Bacteroides gingivalis) were the predominant microorganisms cultured. The humoral immune responses to F. nucleatum, P. gingivalis, and Actinobacillus actinomycetemcomitans were much higher in both subjects than those to any other periodontal bacteria examined. Functional and phenotypic analysis of the peripheral lymphocytes showed no significant abnormalities. However, investigation of neutrophil function showed that the mother had depressed neutrophil chemotaxis and superoxide production. The daughter had depression not only of chemotaxis and superoxide production, but also of neutrophil phagocytosis. Serological typing of HLA antigens revealed the same Class II HLA profile in both subjects. It was concluded that both subjects very probably had an identical condition and that these patients provided a unique model for improving our understanding of the host factors involved in periodontal disease.

Adolescent↗

PubMed1990

Purification and characterization of two major outer membrane proteins from Porphyromonas gingivalis.

Outer membrane proteins (OMPs) were extracted from whole cells of several Porphyromonas and Prevotella strains and their OMPs profiles were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The SDS-PAGE analysis revealed that OMP profiles of Porphyromonas and Prevotella strains show species-specific patterns and P. gingivalis characteristically had two kinds of major outer membrane proteins (MOMPs). A 53 Kd MOMP from P. gingivalis FDC 381 and a 67 Kd MOMP from ATCC 33277 were purified. Sera from periodontitis patients and healthy subjects were analyzed for immunoreactivities against both the purified MOMPs of P. gingivalis by immunoblotting analysis. The sera from 18 patients reacted to the 53 Kd MOMP, 10 to the 67 Kd MOMP, and only three sera reacted to both MOMPs. The sera of healthy subjects also reacted, but weakly, to either the 53 Kd or 67 Kd MOMP. The SDS-PAGE OMP profiles prepared from 13 clinical isolates of P. gingivalis and immunoblotting analysis of human sera against the two kinds of P. gingivalis MOMPs indicate that periodontal diseases resulting from P. gingivalis are initiated and sustained by at least two MOMPs of P. gingivalis.

Bacterial Outer Membrane Proteins↗

PubMed1990

[A case of intrapleural rupture of pulmonary arteriovenous malformation with shock].

We report a case of a 59-year-old male who suddenly developed massive right hemothorax and shock due to pulmonary arteriovenous malformation (AVM). He was admitted as an emergency case because of severe back pain, cyanosis and cold sweat. Although shock with massive right hemothorax was found, echocardiographic and X-ray computed tomographic examination showed no dilatation of the aorta, no intimal flap in the aorta and no pericardial effusion which suggested aneurysm. Pulmonary arteriography, performed subsequently, disclosed intrapleural rupture of the right pulmonary AVM. The patient recovered successfully from the state of shock. The pulmonary AVM was removed by segmentectomy of the right lung (S4). He was discharged following an uneventful postoperative course. Intrapleural rupture with shock is a very rare complication of pulmonary AVM. Pulmonary AVM should be considered as one possible cause in patients with massive hemothorax and shock.

Arteriovenous Malformations↗

PubMed1989

[A case report of Refetoff's syndrome].

An 11-year-old girl with diffuse goiter is presented. She had no clinical evidence of thyrotoxic symptoms or signs of palpitation, excessive sweating, tachycardia or finger tremor. Both the serum T4 (24.0 micrograms/dl) and T3 (282ng/dl) were high, and thyroid 131I uptake rate (63.2%) was significantly elevated, but T3/T4 ratio was not elevated (11.8). BMR was measured three times and remained within normal limits. Her serum TSH was 1.9 microU/ml, and a TRH stimulation test resulted in a normal rise of serum TSH (13.4 microU/ml). The TSH secretion was not suppressed by medication (p.o.) of 75 micrograms of L-triiodothyronine given for 8 days. The autoantibodies of T4, T3 and TSH were negative. No sign of pituitary tumor was observed by plain X-ray film. No defect in her sight-field was found. From these clinical figures and data, Refetoff's syndrome was suspected. She was eumetabolic without any treatment, but the goiter gradually enlarged and dysphagia developed. A large dose of L-thyroxine (450 micrograms/day) was given for a period of one year and four months. She has been eumetabolic. Her goiter disappeared and the dysphagia completely subsided. After she was given large doses of L-T4, her serum TSH was reduced to 0.07 microU/ml and was slightly elevated to 0.24 microU/ml at 30 min after i.v. infusion of 500 micrograms TRH. Thyroid 123I uptake rate was suppressed to 8.3%. According to Refetoff's papers, this case was classified as being in the group with generalized resistance to thyroid hormone.

Child↗

PubMed1989

Hemodynamic shear stress stimulates endothelin production by cultured endothelial cells.

We have examined the effect of shear stress on the production of endothelin by cultured porcine endothelial cells. Low shear stress stimulated the expression of endothelin mRNA in polygonal endothelial cells with a peak time of 2 to 4 hours and also increased the release of immunoreactive endothelin into the culture medium. The expression of endothelin mRNA in the ellipsoidal endothelial cells under higher shear stress was not different from that of the control level. Our results suggest a possible role for hemodynamic shear stress in the regulation of endothelin production in vascular endothelial cells.

Animals↗

PubMed1989

Crystallization of a new class of microbial ribonuclease from Rhizopus niveus.

Crystals of ribonuclease Rh, a new class of microbial ribonuclease from Rhizopus niveus, were obtained from polyethylene glycol 8000 solution by a vapour diffusion technique in the hanging drop mode. Two crystal forms, type I and type II, were obtained from the same droplet solution. Both forms belong to the space group P2(1)2(1)2(1), but their cell dimensions are markedly different: a = 68.3 A, b = 73.0 A, c = 50.0 A for type I and a = 67.5 A, b = 72.3 A, c = 44.2 A for type II. The type I crystals diffract beyond 2.0 A resolution and are suitable for X-ray structure analysis at high resolution.

Crystallization↗

PubMed1989

Transforming growth factor-beta stimulates the expression of endothelin mRNA by vascular endothelial cells.

Endothelin is a potent vasoconstrictor peptide produced by vascular endothelial cells. Incubation of the serum-deprived confluent porcine aortic endothelial cells with 10-300 pM TGF-beta 1, resulted in a several fold increase in endothelin mRNA levels with a peak time of 2 h. An enzyme-linked immunosorbent assay revealed that the levels of endothelin in endothelial cell conditioned media was also increased by TGF-beta 1. These results suggest that TGF-beta 1, secreted by activated platelets, is involved not only in wound healing, but in the regulation of local vascular tone by stimulating endothelin production in the endothelial cells.

Animals↗

PubMed1989

In vitro biotransformation of estradiol by explant cultures of murine mammary tissues.

In vivo experiments have demonstrated a correlation between the extent of 16 alpha-hydroxylation of estradiol and incidence of mammary cancer. The ability of mammary ductal epithelium (MDE), the site for neoplastic transformation, to metabolize estradiol or to accumulate estradiol metabolites has not been unequivocally established. Using a newly developed mammary explant culture system and a radiometric assay, we have compared the site-specific metabolism of estradiol (E2) by the C-17-oxidation and C-16 alpha-hydroxylation pathways in mouse tissues that differ in relative risk for mammary cancer. A comparison between MDE (target tissue) and liver (nontarget tissue) from NFS (low risk) and C3H/ouj (high risk) mice revealed that: a) increase in C-17-oxidation was similar in MDE and liver from the two strains, and b) while C-16 alpha-hydroxylation was similar in liver from the two strains (p = 0.5, n.s.), it was increased 4-fold in the MDE from the high risk C3H/ouj strain relative to that from the low risk NFS strain (p = 0.001). Furthermore, in vivo administration of progesterone resulted in modulation of cell proliferation as well as of E2 metabolism in mammary explant cultures. The effect of progesterone depended upon the presence of the MtV-2 proviral gene. This study demonstrates that mammary explants can extrahepatically metabolize estradiol. The specific risk-related increase in C-16 alpha-hydroxylation suggests that intrinsic metabolic ability of the target tissue leading to the formation of 16 alpha-hydroxyestrone from estradiol may be a determinant in the relative risk for developing mammary cancer.

Animals↗

PubMed1989

Endothelin: a potent vasoconstrictor associated with coronary vasospasm.

Endothelin, administered into the coronary arteries of anesthetized dogs, produced a profound and long-lasting reduction in coronary blood flow with electrocardiographical evidence of myocardial ischemia. Coronary angiography revealed delayed filling of the distal branches and, in some cases, cessation of the blood flow distal to the epicardial portions of coronary arteries. The coronary vasoconstriction induced by endothelin subsided after intracoronary administration of nitroglycerin. Pretreatment with the Ca2+-channel antagonist, nitrendipine, suppressed endothelin-induced vasoconstriction. These findings suggest that endothelin, produced by vascular endothelial cells, may contribute to the pathogenesis of coronary vasospasm.

Animals↗

PubMed1989

Endothelin activates the dihydropyridine-sensitive, voltage-dependent Ca2+ channel in vascular smooth muscle.

Endothelin is a potent endothelium-derived vasoconstrictor peptide recently characterized from porcine and human vascular endothelial cells. Here we provide evidence that endothelin activates the dihydropyridine-sensitive, voltage-dependent Ca2+ channel in porcine coronary artery smooth muscle. The vasoconstrictor action of endothelin is efficiently antagonized by low doses of the dihydropyridine Ca2+-channel blocker nicardipine. Endothelin augments the Ca2+-induced contraction in a high-K+ depolarizing solution, markedly enhances high-threshold Ca2+-channel current on the whole-cell patch clamp recording, and causes a sustained increase in the intracellular Ca2+ that is largely dependent on extracellular Ca2+. These findings suggest that endothelin exerts its vasoconstrictor effect by either directly or indirectly activating the voltage-dependent Ca2+ channel.

Animals↗

PubMed1989

The role of endothelin in the pathogenesis of vasospasm following subarachnoid haemorrhage.

The purpose of the present study was to evaluate the vasocontractile activity of endothelin, a newly isolated endothelium-derived constrictor peptide, in canine basilar arteries in vitro and in vivo. Endothelin at concentrations of 10(-12) M approximately 3 X 10(-8) M elicited dose-dependent contractions of canine basilar arteries in vitro. The maximum tension was larger than that induced by 40 mM KCl. The EC50 value was 1.9 +/- 0.6 X 10(-9) M (mean +/- SEM). The endothelin-induced contraction was reversed by 10(-8) M nicardipine or 10(-5) M approximately 10(-4) M papaverine. An intracisternal injection of 0.6 approximately 1.2 X 10(-12) mol/kg of endothelin caused biphasic contraction of the basilar artery lasting for more than 24 h. The initial phase of the contraction accompanied remarkable changes in vital signs such as an acute rise of blood pressure, bradycardia and respiratory arrest. An intracisternal injection of 2.0 X 10(-12) mol/kg of endothelin also induced acute contraction of the basilar artery. However, all of the dogs which received an intracisternal injection of 2.0 X 10(-12) mol/kg of endothelin died from sustained respiratory insufficiency. The present results demonstrate that endothelin induces strong and long-lasting contractions of cerebral arteries. Therefore, endothelin may play an important role in the pathogenesis of vasospasm.

Angiography↗

PubMed1989

Malacoplakia of the thyroid gland.

A case of malacoplakia of the thyroid gland is described in a 50-year-old Japanese woman. This lesion clinically mimicked a malignant neoplasm, and the true diagnosis of malacoplakia was made only after histologic examination; light microscopy revealed a granulomatous nodule with an accumulation of von Hansemann's histiocytes containing PAS-positive and von Kossa's-positive intracytoplasmic and extracytoplasmic inclusions known as Michaelis-Gutmann bodies. There were some foci consisting of neoplasm-like or hyperplastic residual follicles within the lesion. Electron microscopically, a small number of bacilliform organisms were demonstrated within the lesion. X-ray microanalysis of Michaelis-Gutmann bodies was performed and revealed the presence of phosphorus, calcium, iron, and chloride. It is suggested that the malacoplakic lesion may be associated with the hyperplastic or neoplastic follicular lesion, and bacterial infection could be important in the causation of malacoplakia of the thyroid gland.

Female↗

PubMed1989

The possible role of endothelin-1 in the pathogenesis of coronary vasospasm.

We investigated the in vivo vasoconstrictor effects of endothelin-1 (ET-1) on canine coronary arteries and the regulation of ET-1 gene expression with special reference to the pathogenesis of coronary vasospasm. ET-1, administered into the coronary arteries of anesthetized dogs, produced a profound and long-lasting reduction in coronary blood flow with myocardial ischemia. Coronary angiography revealed delayed filling of the distal branches and, in some cases, total occlusion in the epicardial portions of coronary arteries. The coronary vasoconstriction induced by ET-1 subsided after intracoronary administration of nitroglycerin. Pretreatment with the Ca2+-channel antagonist, nitrendipine, suppressed ET-1-induced vasoconstriction. In cultured porcine aortic endothelial cells, ET-1 gene expression was induced by agents related to thrombus formation, such as thrombin and transforming growth factor beta (TGF beta). These findings suggest that ET-1, produced by vascular endothelial cells, may contribute to the regulation of coronary circulation and the pathogenesis of coronary vasospasm with respect to intimal injury and subsequent thrombus formation.

Angiocardiography↗