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Biomedical subjects

H Ishihara

Publications and source records attributed to H Ishihara.

At least 37 records · Page 2Linked to original sources
PubMed2003

Differential effects of thiopental on methacholine- and serotonin-induced bronchoconstriction in dogs.

BACKGROUND: Thiopental sometimes causes bronchospasm during induction of anaesthesia. In addition, we have reported previously that thiopental produced transient bronchospasm, which was blocked by atropine pretreatment, and worsened histamine-induced bronchoconstriction in dogs. Previous in vitro reports suggest that synthesis of contractile cyclooxygenase products, such as thromboxane A(2), may be involved in the mechanism of bronchospasm. However, the in vivo spastic effects have not been defined comprehensively. METHODS: Twenty-seven mongrel dogs were anaesthetized with pentobarbital. Bronchoconstriction was elicited with methacholine (0.5 microg kg(-1)+5.0 microg kg(-1) min(-1); Mch group, n=7) or serotonin (10 microg kg(-1)+1 mg kg(-1) h(-1); 5HT group, n=20), and assessed as percentage changes in bronchial cross-sectional area (BCA, basal=100%) using a bronchoscope. In the 5HT group, dogs were subdivided into four groups of five each: S-5HT, I-5HT, 5HT-S and 5HT-A. In the S-5HT and I-5HT groups, 30 min before serotonin infusion dogs were given saline and indomethacin respectively at 5 mg kg(-1) i.v. In all groups, 30 min after bronchoconstrictor infusion started, dogs were given thiopental at doses between 0 (saline) and 20 mg kg(-1). In the 5HT-S and 5HT-A groups, dogs were given saline or atropine 0.2 mg kg(-1) i.v. 5 min after thiopental 20 mg kg(-1). RESULTS: Methacholine and serotonin reduced BCA by about 50 and 40% respectively. Thiopental 20 mg kg(-1) increased and decreased BCA by about 20 and 10% in the Mch and 5HT groups respectively. Indomethacin and atropine did not attenuate the potentiation of serotonin bronchoconstriction produced by thiopental. CONCLUSION: The present study indicates that thiopental may attenuate or worsen bronchoconstriction induced by muscarinic or serotonin receptor stimulation, respectively. The synthesis of contractile cyclooxygenase products and cholinergic stimulation may not be involved in the contractile effect of thiopental on serotonin bronchoconstriction.

Anesthetics, Intravenous↗
PubMed2002

Surgical prognosis of unruptured cerebral aneurysms. Report of 40 cases in University Hospital Zurich.

A series of 40 patients admitted to University Hospital Zurich (1996-97) with unruptured cerebral aneurysms is reported. Fifty-two aneurysms were treated in 40 operations. The age of surgically treated patients ranged from 31 to 78 year old (mean 53.6). The main locations of the aneurysms were: MCA 21 (40.4%), AcomA 10 (19.2%), ICA (posterior communicating and bifurcation) 6 (11.5%), carotid-ophthalmic segment 4 (7.7%), ACA 4 (7.7%), basilar tip 3 (5.8%), vertebral artery 2 (3.8%). The circumstances of diagnosis were: incidental 15 (37.5%), other cranial lesions 9 (22.5%), symptomatic 8 (20%), multiple aneurysm 8 (20%). The overall outcome of surgery was: good recovery in 39 cases (97.5%), moderately disabled in 1 case (2.5%) who was 56 year-old and had three aneurysms including basilar tip. There was no operative mortality. Though this series has small number of patients, it suggests that location of the aneurysm is an important factor affecting surgical outcome among patient age, the circumstances of the diagnosis, size and location of aneurysm.

Adult↗
PubMed2002

Endometriosis: the pathophysiology as an estrogen-dependent disease.

Endometriosis, defined as the presence of endometrial glands and stroma outside of the uterine cavity, develops mostly in women of reproductive age and regresses after menopause or ovariectomy, suggesting that the growth is estrogen-dependent. Indeed, the lesions contain estrogen receptors (ER) as well as aromatase, an enzyme that catalyses the conversion of androgens to estrogens, suggesting that local estrogen production may stimulate the growth of lesions. The expression patterns of ER and progesterone receptors in endometriotic lesions are different from those in the eutopic endometrium. Moreover, estrogen metabolism, including the expression pattern of aromatase and the regulation of 17 beta-hydroxysteroid dehydrogenase type 2 (an enzyme responsible for the inactivation of estradiol to estrone), is altered in the eutopic endometrium of women with endometriosis, adenomyosis, and/or leiomyomas compared to that in the eutopic endometrium of women without disease. Immunostaining for P450arom in endometrial biopsy specimens diagnosed these diseases with sensitivity and specificity of 91 and 100%, respectively. This is applicable to the clinical diagnosis of endometriosis. The polymorphisms in the ER-alpha gene, the CYP19 gene encoding aromatase, and several other genes are associated with the risk of endometriosis. Studies of these will lead to better understandings of the etiology and pathophysiology of endometriosis.

17-Hydroxysteroid Dehydrogenases↗
PubMed2002

Lung image changes during bronchopulmonary lavage estimated using transoesophageal echocardiography.

Pulmonary alveolar proteinosis is often treated with bronchopulmonary lavage. Transoesophageal echocardiography has been used to detect lung atelectasis in critical situations. A 68-yr-old male with pulmonary alveolar proteinosis underwent bronchopulmonary lavage and was examined using transoesophageal echocardiography. His dependent left-lung area was observed through the descending aorta. Following saline infusion, no bright areas containing air were observed. The average area of the air-free region following instillation was 37.4 +/- 1.8 cm2, which decreased to 22.8 +/- 2.6 cm2 after drainage (P < 0.001). There was a significant relationship between the percentage venous admixture and air-free area during lavage (P < 0.05, r = -0.76). The image of the right lung was unclear. Transoesophageal echocardiography can yield useful information about the lung during bronchopulmonary lavage.

Aged↗
PubMed2002

Ketamine and the inhibition of albumin extravasation in chemical peritonitis in rat.

BACKGROUND AND OBJECTIVE: It was previously reported that topical ketamine inhibits albumin extravasation in a rat chemical peritonitis model. Using the same model, the present study investigated whether intravenous ketamine inhibited this extravasation. METHODS: Twenty-four rats anaesthetized with pentobarbital (75 mg kg(-1)) were randomly assigned to two groups: ketamine and a 0.9% NaCl (saline) group (n = 12 each). Ketamine 1% or saline 0.1 mL kg(-1) min(-1) was given intravenously for 60 min to the respective group. After the abdomen had been opened, peritonitis was elicited by topically applying a filter paper containing 0.02 M HCl 0.07 mL onto the surface of the appendix or caecum for 5 min. Fifteen minutes after removal of the filter paper, Evans' blue dye (50 mg kg(-1)) was injected intravenously. The extravasated dye was colorimetrically quantified by a spectrophotometer at 620 nm. RESULTS: The infusion of ketamine significantly reduced Evans' blue extravasation: 5.26 (range 4.18-6.34) microg per 100 mg tissue compared with the saline group control: 6.81 (5.93-7.69) microg per 100 mg tissue (P < 0.05). CONCLUSIONS: It is suggested that ketamine anaesthesia may reduce albumin extravasation in inflammatory tissues.

Albumins↗
PubMed2001

Daily changes of the area of density in the dependent lung region - evaluation using transesophageal echocardiography.

OBJECTIVE: To evaluate the daily changes of the area of density using transesophageal echocardiography (TEE) in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) patients. DESIGN: Retrospective observational study. SETTING: General ICU in a university hospital. PATIENTS: Fifteen patients with ARDS or ALI who underwent TEE examination for more than 5 days. MEASUREMENTS: Densities in the lower left lung region were observed through the descending aorta by TEE. Daily changes of the area of density were evaluated. The areas of density estimated by TEE were compared with those obtained by computed tomography (CT). The relation between the area of density and PaO(2)/FIO(2)was calculated. RESULTS: The area of density in the dependent lung region measured by TEE was 11.1+/-5.7 cm(2) (mean +/- SD) at the mid-esophageal position. The area of density in ARDS patients changed daily from 12.0+/-2.8 cm(2) to 8.5+/-6.7 cm(2). The areas of density evaluated using TEE in the left lung correlated significantly with those estimated using CT ( r=0.72, p<0.01). In addition, we found a significant correlation between PaO(2)/FIO(2) and the area of density estimated by TEE ( r=-0.53, p<0.05). CONCLUSION: Using TEE, we could evaluate daily changes of the area of density in the dependent lung region in the intensive care situation. The areas of density in ARDS patients changed from day to day following the changes of oxygenation.

Adult↗
PubMed2001

GAD65-mediated glutamate decarboxylation reduces glucose-stimulated insulin secretion in pancreatic beta cells.

Mitochondrial metabolism plays a pivotal role in the pancreatic beta cell by generating signals that couple glucose sensing to insulin secretion. We have demonstrated previously that mitochondrially derived glutamate participates directly in the stimulation of insulin exocytosis. The aim of the present study was to impose altered cellular glutamate levels by overexpression of glutamate decarboxylase (GAD) to repress elevation of cytosolic glutamate. INS-1E cells infected with a recombinant adenovirus vector encoding GAD65 showed efficient overexpression of the GAD protein with a parallel increase in enzyme activity. In control cells glutamate levels were slightly increased by 7.5 mm glucose (1.4-fold) compared with the effect at 15 mm (2.3-fold) versus basal 2.5 mm glucose. Upon GAD overexpression, glutamate concentrations were no longer elevated by 15 mm glucose as compared with controls (-40%). Insulin secretion was stimulated in control cells by glucose at 7.5 mm (2.5-fold) and more efficiently at 15 mm (5.2-fold). INS-1E cells overexpressing GAD exhibited impaired insulin secretion on stimulation with 15 mm glucose (-37%). The secretory response to 30 mm KCl, used to raise cytosolic Ca(2+) levels, was unaffected. Similar results were obtained in perifused rat pancreatic islets following adenovirus transduction. This GAD65-mediated glutamate decarboxylation correlating with impaired glucose-induced insulin secretion is compatible with a role for glutamate as a glucose-derived factor participating in insulin exocytosis.

Adenosine Triphosphate↗
PubMed2001

Image-guided anterior thoracolumbar corpectomy: a report of three cases.

STUDY DESIGN: A report of three cases of thoracolumbar vertebral collapse treated with image-guided anterior corpectomy. OBJECTIVES: To document the surgical technique and the usefulness of image-guided anterior corpectomy for thoracolumbar vertebral collapse. SUMMARY OF BACKGROUND DATA: Computer-assisted navigation systems can provide accurate three-dimensional surgical information intraoperatively. However, there is no clinical report regarding the application and usefulness of the computer-assisted navigation system for anterior thoracolumbar corpectomy. METHODS: After exposure of anterior and lateral aspects of the vertebral bodies through the transpleural approach, a reference frame was fixed to the thoracolumbar spinous process. Then thoracolumbar corpectomy and decompression were carried out under computer assistance. RESULTS: The tip of the standard probe and the angled rongeur could be monitored on three-dimensional images during surgery, and the retropulsed fragments within the spinal canal could be safely and completely removed under computer assistance. CONCLUSION: This image-guided procedure would aid surgeons in the complete and safe decompression of thoracolumbar injury.

Aged↗
PubMed2001

Pdx1 level defines pancreatic gene expression pattern and cell lineage differentiation.

The absence of Pdx1 and the expression of brain-4 distinguish alpha-cells from other pancreatic endocrine cell lineages. To define the transcription factor responsible for pancreatic cell differentiation, we employed the reverse tetracycline-dependent transactivator system in INS-I cell-derived subclones INSralphabeta and INSrbeta to achieve tightly controlled and conditional expression of wild type Pdx1 or its dominant-negative mutant, as well as brain-4. INSralphabeta cells express not only insulin but also glucagon and brain-4, while INSrbeta cells express only insulin. Overexpression of Pdx1 eliminated glucagon mRNA and protein in INSralphabeta cells and promoted the expression of beta-cell-specific genes in INSrbeta cells. Induction of dominant-negative Pdx1 in INSralphabeta cells resulted in differentiation of insulin-producing beta-cells into glucagon-containing alpha-cells without altering brain4 expression. Loss of Pdx1 function alone in INSrbeta cells, which do not express endogenous brain-4 and glucagon, was also sufficient to abolish the expression of genes restricted to beta-cells and to cause alpha-cell differentiation. In contrast, induction of brain-4 in INSrbeta cells initiated detectable expression of glucagon but did not affect beta-cell-specific gene expression. In conclusion, Pdx1 confers the expression of pancreatic beta-cell-specific genes, such as genes encoding insulin, islet amyloid polypeptide, Glut2, and Nkx6.1. Pdx1 defines pancreatic cell lineage differentiation. Loss of Pdx1 function rather than expression of brain4 is a prerequisite for alpha-cell differentiation.

Animals↗
PubMed2001

Clinical features of extraforaminal lumbar disc herniation based on the radiographic location of the dorsal root ganglion.

STUDY DESIGN: The relations between the location of the dorsal root ganglion and pre- and postoperative symptoms were reviewed retrospectively in 27 patients who underwent radiculography and posterior discectomy. OBJECTIVES: To evaluate the clinical features and surgical outcome of extraforaminal lumbar disc herniation based on the location of dorsal root ganglion. SUMMARY OF BACKGROUND DATA: The location of dorsal root ganglia has been reported to be correlated with a variety of radicular symptoms. Extraforaminal lumbar disc herniation has several specific clinical features, one of which is severe radicular pain. However, there is no report in the literature on the association between the location of the dorsal root ganglia and the severity of the symptoms of extraforaminal lumbar disc herniation. METHODS: The radiographic location of the dorsal root ganglion of each compressed nerve root was determined by preoperative direct radiculograms. All patients were classified into the following three groups according to the location of dorsal root ganglion: intraspinal, intraforaminal, and extraforaminal. The incidences of these locations were 5 of 27 (18.5%), 15 of 27 (55.5%), and 7 of 27 (25.9%), respectively. The relation between the location of the dorsal root ganglion and clinical parameters such as the level of the compressed nerve root, the degree of limitation on straight leg raising test, the severity of the pre- and postoperative subjective symptoms (leg pain, low back pain, and walking capacity), clinical signs (sensory and motor disturbance), and the recovery rate were investigated. RESULTS: The degree of limitation on the straight leg raising test in the extraforaminal group tended to be low, compared with that in the intraspinal and intraforaminal groups. Low back pain in the extraforaminal group was more severe than that in the intraspinal and intraforaminal groups. Preoperative leg pain in the extraforaminal group was significantly more severe that that in the intraspinal group, and the walking capacity in the extraforaminal group tended to be lower than that in the intraspinal and intraforaminal groups. No significant differences were found between the location of dorsal root ganglion and the preoperative sensory or motor disturbance and surgical outcomes. CONCLUSION: The location of the dorsal root ganglion might influence the severity of radicular symptoms (pain and walking distance tolerance) in patients with extraforaminal lumbar disc herniation.

Adult↗
PubMed2001

Phosphatidylinositol 4,5-bisphosphate induces actin stress-fiber formation and inhibits membrane ruffling in CV1 cells.

Phosphatidylinositol 4,5 bisphosphate (PIP(2)) is widely implicated in cytoskeleton regulation, but the mechanisms by which PIP(2) effect cytoskeletal changes are not defined. We used recombinant adenovirus to infect CV1 cells with the mouse type I phosphatidylinositol phosphate 5-kinase alpha (PIP5KI), and identified the players that modulate the cytoskeleton in response to PIP(2) signaling. PIP5KI overexpression increased PIP(2) and reduced phosphatidylinositol 4 phosphate (PI4P) levels. It promoted robust stress-fiber formation in CV1 cells and blocked PDGF-induced membrane ruffling and nucleated actin assembly. Y-27632, a Rho-dependent serine/threonine protein kinase (ROCK) inhibitor, blocked stress-fiber formation and inhibited PIP(2) and PI4P synthesis in cells. However, Y-27632 had no effect on PIP(2) synthesis in lysates, although it inhibited PI4P synthesis. Thus, ROCK may regulate PIP(2) synthesis by controlling PI4P availability. PIP5KI overexpression decreased gelsolin, profilin, and capping protein binding to actin and increased that of ezrin. These changes can potentially account for the increased stress fiber and nonruffling phenotype. Our results establish the physiological role of PIP(2) in cytoskeletal regulation, clarify the relation between Rho, ROCK, and PIP(2) in the activation of stress-fiber formation, and identify the key players that modulate the actin cytoskeleton in response to PIP(2).

ADP Ribose Transferases↗
PubMed2001

A novel missense mutation in the early growth response 2 gene associated with late-onset Charcot--Marie--Tooth disease type 1.

A novel mutation (Arg381Cys) in the second zinc-finger domain of early growth response 2 (EGR2) was identified in a late-onset Charcot--Marie--Tooth disease type 1 (CMT1) patient. This patient had initial symptoms of numbness and weakness in the leg at age 59, and a median nerve motor conduction velocity of 27 m/s. A sural nerve biopsy showed a severe loss of myelinated fibers with numerous onion bulbs. This is the first report of the EGR2 mutation presenting a late onset of CMT1 phenotype. Its mutation was a different amino acid substitution at codon 381 (Arg381His) which demonstrated congenital hypomyelinating neuropathy or early-onset CMT1. This report suggests that the EGR2 mutation represents divergent phenotypes at codon 381, which may be a mutation hotspot.

Aged↗
PubMed2001

Enhanced expression of the early retrotransposon in C3H mouse-derived myeloid leukemia cells.

Cells of acute myeloid leukemia (AML) from C3H/He mice express an increased amount of RNA for an endogenous retrovirus-like retrotransposon, intracisternal A-particle element. We analyzed the transcription of other mouse retrotransposons in C3H-derived tumor cells and found that all the AML lines from different mice overexpress early-transposon (ETn) RNA. In contrast, only faint levels of ETn were detected in the cells from other tumors, including hepatoma and lymphoma. The polyadenylation sites of the ETn RNA in the AML cells varied. We also determined the binding site for the nuclear extract of the AML cells in the long terminal repeat sequence of ETn. The overexpression of ETn as a common phenotype of AML cells suggests that myeloid cells with this phenotype are the origin of all the AML cells or that the phenotype is acquired during leukemogenesis.

Animals↗
PubMed2001

Nitric oxide mediates the change of proteoglycan synthesis in the human lumbar intervertebral disc in response to hydrostatic pressure.

STUDY DESIGN: This in vitro study clarifies the role of nitric oxide (NO) in human lumbar intervertebral disc metabolism. OBJECTIVE: To investigate the effects of NO on proteoglycan synthesis in human lumbar discs and to test the hypothesis that NO is a mediator of the changes in proteoglycan synthesis in response to hydrostatic pressure. SUMMARY OF BACKGROUND DATA: The authors have clarified that hydrostatic pressure has an apparent effect on proteoglycan synthesis as well as matrix metalloproteinase production in the intervertebral disc. The cellular mechanisms underlying the response of disc cells to hydrostatic pressure remain to be clarified. Herniated lumbar discs produce NO in response to interleukin (IL)-1 beta. In articular cartilage, NO mediates the change of proteoglycan synthesis by IL-1 or shear stress. METHODS: Fifty-eight lumbar intervertebral disc specimens were obtained from patients who had undergone posterior discectomy. The specimens were chopped into 1-2-mm cubes and were incubated in a plastic syringe with 1 mL Dulbecco's modified Eagle's medium (DMEM). The syringes were placed in a water-filled pressure vessel kept at 37 C. Hydrostatic pressures of 1 (control), 3, and 30 atmospheres (atm) were applied. Proteoglycan synthesis was determined from (35)S-sulfate incorporation rates. Nitrite (the stable oxidation product of NO) concentration in DMEM was determined by a spectrophotometric method based on the Griess reaction. As a competitive inhibitor of NO synthases, N(G)-methyl-l-arginine (l-NMA, 10-1000 micromol) and as an organic donor of NO, S-nitroso-N-acetylpenicillamine (SNAP, 1-200 micromol) were used. RESULTS: Addition of l-NMA suppressed NO production and increased proteoglycan synthesis rates in the intervertebral disc specimens in a dose-dependent fashion. Addition of SNAP increased exogenous NO content in the medium significantly and suppressed proteoglycan synthesis rates in a dose-dependent fashion. Three-atmosphere hydrostatic pressure stimulated the proteoglycan synthesis rates. Rates were approximately 1.3-fold greater than at 1 atm, whereas 30-atm pressure inhibited proteoglycan synthesis rates. However, the hydrostaticpressure had inverse effect on NO production. At 3 atm, NO production decreased slightly relative to 1 atm, whereas at a pressure of 30 atm, NO production was increased and was approximately 1.32-fold greater than at 1 atm. L-NMA enhanced the 3-atm pressure-induced increase in proteoglycan synthesis and also relieved the suppression of proteoglycan synthesis at a pressure of 30 atm. CONCLUSION: The current study confirmed the previous finding that human herniated lumbar disc cultures spontaneously produce NO. Endogenously generated and exogenously supplied NO inhibited proteoglycan synthesis in the intervertebral disc. Hydrostatic pressure influenced NO production by disc cells, and NO is one of the mediators that changes proteoglycan synthesis in response to hydrostatic pressure. These results may show that autocrine and paracrine mechanisms of NO play an important role in the regulation of disc cell metabolism under mechanical stress and in the pathophysiology of intervertebral disc degeneration.

Adolescent↗
PubMed2001

Causality of the brane universe.

Causal structure of the brane universe with respect to null geodesics in the bulk spacetime is studied. It is pointed out that apparent causality violation is possible for the brane universe which contains matter energy. It is also shown that there is no "horizon problem" in the Friedmann-Robertson-Walker brane universe.

Journal Article↗