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Biomedical subjects

T Ishikawa

Publications and source records attributed to T Ishikawa.

At least 289 records · Page 16Linked to original sources
PubMed2000

Characterization of spinal amino acid release and touch-evoked allodynia produced by spinal glycine or GABA(A) receptor antagonist.

Intrathecal strychnine (glycine antagonist) or bicuculline (GABA(A) antagonist) yields a touch-evoked agitation that is blocked by N-methyl-D-aspartate receptor antagonism. We examined the effects of intrathecal strychnine and bicuculline on touch-evoked agitation and the spinal release of amino acids. Fifty-two Sprague-Dawley rats were prepared under halothane anesthesia with a lumbar intrathecal catheter and a loop dialysis catheter. Four days after implantation, rats were randomized to receive an intrathecal injection of N-methyl-D-aspartate (3 microg), strychnine (3 microg) or bicuculline (10 microg), or a combination of N-methyl-D-aspartate with bicuculline or strychnine. The agitation produced by brief light tactile stroking of the flank (tactile allodynia), and the spontaneous spinal release of glutamate, taurine and serine was measured. Intrathecal N-methyl-D-aspartate, strychnine and bicuculline produced similar touch-evoked allodynia. Intrathecal bicuculline and N-methyl-D-aspartate alone evoked a transient spinal release of glutamate and taurine, but not serine, in the 0- 10 min sample, while strychnine did not affect spinal transmitter release at any time. As GABA(A) but not glycine receptor inhibition at equi-allodynic doses increases glutamate release, while the allodynia of both is blocked by N-methyl-D-aspartate receptor antagonism, we hypothesize that GABA(A) sites regulate presynaptic glutamate release, while glycine regulates the excitability of neurons postsynaptic to glutamatergic terminals.

Amino Acids↗
PubMed2000

Ictal increased writing preceded by dysphasic seizures.

Ictal increased writing has never been concretely demonstrated to be an epileptic symptom. We reported the evolution of seizures, from the beginning of reading-writing dysphasia through increased writing to secondary generalization, in a schoolchild with benign partial seizures. The lateralizing value of inter- or non-ictal hypergraphia has been stressed for the right hemisphere, while ictal increased writing most likely originated from the language area in the dominant (left) cerebral hemisphere in our patient.

Aphasia↗
PubMed2000

Pathophysiology and diagnosis of primary hyperparathyroidism--strategy for asymptomatic primary hyperparathyroidism.

Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia due to excessive secretion of PTH, is usually associated with hypophosphatemia and elevated serum chloride. Although PHPT was often complicated by renal stone disease and osteitis fibrosa in the past, routine screening of serum calcium (Ca) and development of sophisticated assay of parathyroid hormone have contributed to earlier detection of asymptomatic PHPT (APHPT). The proportion of APHPT patients, who have a mild elevation of serum Ca levels, usually within 1.0 mg/dL above the upper limit of normal, rose from 10-20% to approximately 45% of all PHPT patients in 1990-1995 in our clinic. Although it has been reported that the prevalence of PHPT is about 0.1% of the American population, the prevalence of PHPT appears to be far less in the Japanese population. Determination of a strategy for the increasing number of APHPT patients, is a pressing need but has yet to be accomplished. Treatment with bone antiresorptive drugs has met with some success, although the long-term efficacy of this treatment is not clear. The therapeutic effects of Ca-sensing receptor agonists appear promising.

Hormone Antagonists↗
PubMed2000

Laparoscopic adrenalectomy for benign adrenal tumors.

Laparoscopic adrenalectomy has been rapidly accepted for treatment of benign adrenal tumors. To evaluate the advantages of laparoscopic adrenalectomy, we examined 55 patients who underwent laparoscopic adrenalectomy. In all patients, adrenal tumors were successfully removed. The mean operating time was 143 minutes, and the estimated mean blood loss was 49 mL in all patients. The postoperative course was uneventful in all cases. The mean frequency of administration of analgesics was only 2.9 times, and the time elapsed to first walking after surgery was 17 hours. The peak white blood cell count and C-reactive protein values after surgery were 8,266 +/- 1,963/mm3 and 2.5 +/- 1.2 mg/dL, respectively. Of the 55 patients, 44 underwent total adrenalectomy and another 11 underwent partial adrenalectomy, which was introduced in the expectation of preserving normal adrenal cortex; it is therefore indicated in solitary and peripherally located benign tumors. The mean operating time was 154 minutes for the total adrenalectomy, which was longer than that of partial adrenalectomy (92 minutes). The estimated blood loss was 50 mL for the total and 46 mL for the partial adrenalectomy. The postoperative course was uneventful and surgical outcome was excellent in each group. In conclusion, our results are encouraging enough to suggest that laparoscopic adrenalectomy should be a preferential therapeutic option for benign adrenal tumors; also, partial adrenalectomy could be a safe, effective, and less invasive procedure in selected cases.

Adrenal Gland Neoplasms↗
PubMed2000

Compressive optic nerve atrophy resulting from a distorted internal carotid artery.

An 18-month-old female with right compressive optic nerve atrophy caused by an ipsilateral distorted internal carotid artery is reported. She was referred to an ophthalmologist at 8 months of age with the complaint of unilateral visual loss. Neuroimaging studies should contribute markedly to the determination of the causes of visual problems in young children.

Carotid Artery, Internal↗
PubMed2000

Visualization of substrate binding and translocation by the ATP-dependent protease, ClpXP.

Binding and internalization of a protein substrate by E. coli ClpXP was investigated by electron microscopy. In sideviews of ATP gamma S-stabilized ClpXP complexes, a narrow axial channel was visible in ClpX, surrounded by protrusions on its distal surface. When substrate lambda O protein was added, extra density attached to this surface. Upon addition of ATP, this density disappeared as lambda O was degraded. When ATP was added to proteolytically inactive ClpXP-lambda O complexes, the extra density transferred to the center of ClpP and remained inside ClpP after separation from ClpX. We propose that substrates of ATP-dependent proteases bind to specific sites on the distal surface of the ATPase, and are subsequently unfolded and translocated into the internal chamber of the protease.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2000

Randomized controlled trial of twice-a-day administration of natural interferon beta for chronic hepatitis C.

We conducted a randomized controlled trial to assess the efficacy of twice-a-day administration of natural interferon beta (IFNbeta) as an induction of IFN therapy for chronic hepatitis C. Seventy-one patients with chronic hepatitis C were enrolled into the trial and randomly assigned into three treatment groups. Six million units (MU) of IFNbeta were administered once-a-day for the first 4 weeks, and then thrice weekly for 12 weeks in 20 patients (once-a-day group). Three milion units of IFNbeta were administered twice-a-day for the first 2 weeks, 6 MU once-a-day for the next 2 weeks, and then thrice weekly for 12 weeks in 23 patients (twice-a-day+beta group), or 6 MU of lymphoblastoid IFNalpha were administered thrice weekly for the last 12 weeks instead of IFNbeta in 28 patients (twice-a-day+alpha group). Four patients in once-a-day group (20%), 9 in twice-a-day+beta group (39%), and 12 in twice-a-day+alpha group (43%) obtained sustained response. Sustained response rate in twice-a-day groups was higher than in once-a-day group, although there was no statistical significance. The present study suggested the possible superiority of twice-a-day administration of IFNbeta as an induction therapy to once-a-day administration, but further studies are needed to confirm this regimen.

Journal Article↗
PubMed2000

Identification of deoxymiroestrol as the actual rejuvenating principle of "Kwao Keur", Pueraria mirifica. The known miroestrol may be an artifact.

Miroestrol (1) has been isolated previously as an active principle from "Kwao Keur" (Pueraria mirifica), a rejuvenating folk medicine from Thailand. Reinvestigation using bioassay-guided purification has resulted in the isolation of a new potent phytoestrogen, deoxymiroestrol (2). The facile aerial oxidation of 2 into 1 suggests the possibility that 1 may be an artifact.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Time course of brain neuronal degeneration and heat shock protein (72) expression following neck tourniquet-induced cerebral ischemia in the rat.

1. The present study was designed to examine the regional expression of HSP72/73 protein after a 7.5-min period of cerebral ischemia and to compare the distribution of HSP neurons with the localization of irreversible neuronal degeneration as analyzed by silver impregnation technique. 2. During 6-24 hr after cerebral ischemia clear-cut neuronal argyrophilia developed in several brain regions including the hippocampal hilus, nucleus reticularis thalami, and colliculi inferiores. With the exception of the hippocampal hilus, the structures which showed silver impregnability were HSP72 negative at 6-24 hr. 3. Despite the clear HSP72 expression seen in hippocampal CA1 neurons, a significant loss of these neurons was seen at 7 days after ischemia. 4. These data show that in some structures the presence of HSP72 is indicative of higher resistance of these neurons to ischemia-induced degeneration, however, the process of delayed neuronal degeneration appears to be independent of the accelerated synthesis of HSP72 seen during the early period of reflow.

Animals↗
PubMed2000

Transient spinal cord ischemia in rat: the time course of spinal FOS protein expression and the effect of intraischemic hypothermia (27 degrees C).

1. In the present study, we characterize the time course of spinal FOS protein expression after transient noninjurious (6-min) or injurious (12-min) spinal ischemia induced by inflation of a balloon catheter placed into the descending thoracic aorta. In addition, this work examined the effects of spinal hypothermia on FOS expression induced either by ischemia or by potassium-evoked depolarization (intrathecal KCl). 2. Short-lasting (6-min) spinal ischemia evoked a transient FOS protein expression. The peak expression was seen 2 hr after reperfusion in all laminar levels in lumbosacral segments. At 4 hr of reperfusion, more selective FOS expression in spinal interneurons localized in the central part of laminae V-VII was seen. At 24 hr no significant increase in FOS protein was detected. 3. After 12 min of ischemia and 2 hr of reflow, nonspecific FOS expression was seen in both white and gray matter, predominantly in nonneuronal elements. Intrathecal KCl-induced FOS expression in spinal neurons in the dorsal horn and in the intermediate zone. Spinal hypothermia (27 degrees C) significantly suppressed FOS expression after 6 or 12 min of ischemia but not after KCl-evoked depolarization. 4. Data from the present study show that an injurious (but not noninjurious) interval of spinal ischemia evokes spinal FOS protein expression in glial cells 2 hr after reflow. The lack of neuronal FOS expression corresponds with extensive neuronal degeneration seen in this region 24 hr after reflow. Noninjurious (6-min) ischemia induced a transient, but typically neuronal FOS expression. The significant blocking effect of hypothermia (27 degrees C) on the FOS induction after ischemia but not after potassium-evoked depolarization also suggests that simple neuronal depolarization is a key trigger in FOS induction.

Animals↗
PubMed2000

p53, bcl-2 and bax abnormalities in non-Hodgkin's lymphomas of the head and neck.

In the present study, mutations or protein expression of p53, bcl-2 and bax are reported in 13 non-Hodgkin's B-cell lymphomas of the head and neck. Nine of 13 cases (69.2%) expressed p53 protein and 7 (53.8%) showed gene mutations. On comparing the results of immunostaining and SSCP analysis, there were two cases showing discrepancies between the p53 protein expression and gene mutations. Bcl-2 protein expression was observed in only two cases of follicular lymphoma. On the other hand, bax protein was detected in all 13 cases. One case with mutated bax gene showed a lower expression with a reduced frequency of bax-positive cells than the other 12. These results suggest that inactivation of p53 may be closely related to development and/or progression of these NHLs, and that bcl-2 and bax protein may not have a role.

Adolescent↗
PubMed2000

In vivo detection of ultraviolet photoproducts and their repair in purkinje cells.

We previously developed a highly sensitive method to assess in situ repair kinetics of ultraviolet (UV)-induced DNA photoproducts in epidermal cells using monoclonal antibodies specific for cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts (64PPs) by immunohistochemistry. In order to determine whether nucleotide excision repair capacity is operative in postmitotic mature neurons, brain surfaces of adult mice were exposed to UVB, and induction and removal of CPDs and 64PPs in Purkinje cell DNA were assessed immunohistochemically. UVB penetrated brain tissue to a depth sufficient to allow quantitative study. CPDs but not 64PPs were clearly detectable in the nuclei of Purkinje cells at doses >500 J/m2, in a dose-dependent manner. A time course experiment showed a statistically significant decrease of CPDs with time after irradiation. Although there was no apparent removal on Day 1, about half of CPDs were removed within 5 days, and the repair was essentially completed by Day 10. We conclude that non-dividing cerebellar neuronal cells can indeed repair UV-induced DNA damage, but with relatively low efficiency as compared with dividing epidermal cells.

Animals↗
PubMed2000

Specific inhibition of stretch-induced increase in L-type calcium channel currents by herbimycin A in canine basilar arterial myocytes.

The effects of protein-tyrosine kinase (PTK) and protein-tyrosine phosphatase (PTP) inhibitors on voltage-activated barium currents (I(Ba)) through L-type calcium channels increased by hypotonic solution were investigated in canine basilar arterial myocytes by the whole-cell patch-clamp technique. I(Ba) was elicited by depolarizing step from a holding potential of -80 to +10 mV and identified by using an L-type calcium channel agonist, Bay K 8644 (100 nM), and an L-type calcium channel blocker, nicardipine (1 microM). Hypotonic superfusate induced cell swelling and acted as a stretch stimulus, which reversibly increased peak I(Ba) amplitude at +10 mV. I(Ba) was also decreased by nicardipine (1 microM) under the hypotonic condition. PTK inhibitors such as herbimycin A (30 nM), genistein (10 microM), and lavendustin A (10 microM) decreased I(Ba) enhanced by hypotonic solution. Genistein also decreased I(Ba) in a concentration-dependent manner under the isotonic condition. The inactive genistein analogue daidzein (10 microM) had no effect on I(Ba) under either the isotonic or hypotonic condition. By contrast, herbimycin A did not decrease I(Ba) under the isotonic condition. Sodium orthovanadate (10 microM), a PTP inhibitor, increased I(Ba) under both conditions. The present results suggest that cell swelling by hypotonic solution increases the L-type calcium channel currents in canine basilar artery and that herbimycin-sensitive PTK activity is primarily involved in the enhancement of calcium channel currents.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Molecular analysis of zebrafish photolyase/cryptochrome family: two types of cryptochromes present in zebrafish.

BACKGROUND: Cryptochromes (CRY), members of the DNA photolyase/cryptochrome protein family, regulate the circadian clock in animals and plants. Two types of animal CRYs are known, mammalian CRY and Drosophila CRY. Both CRYs participate in the regulation of circadian rhythm, but they have different light dependencies for their reactions and have different effects on the negative feedback loop which generates a circadian oscillation of gene expression. Mammalian CRYs act as a potent inhibitor of transcriptional activator whose reactions do not depend on light, but Drosophila CRY functions as a light-dependent suppressor of transcriptional inhibitor. RESULTS: We cloned seven zebrafish genes that carry members of the DNA photolyase/cryptochrome protein family; one (6-4)photolyase and six cry genes. A sequence analysis and determination of their in vitro functions showed that these zebrafish cry genes constitute two groups. One has a high sequence similarity to mammalian cry genes and inhibits CLOCK:BMAL1 mediated transcription. The other, which has a higher sequence similarity to the Drosophila cry gene rather than the mammalian cry genes, does not carry transcription inhibitor activity. The expressions of these cry genes oscillate in a circadian manner, but their patterns differ. CONCLUSIONS: These findings suggest that functionally diverse cry genes are present in zebrafish and each gene has different role in the molecular clock.

ARNTL Transcription Factors↗
PubMed2000

Expression of hepatic thrombopoietin mRNA in primary cultured hepatocytes and in rats with acute liver injury or bone marrow suppression with or without cirrhosis.

BACKGROUND AND AIMS: The main causes of thrombocytopenia in cirrhosis are thought to be platelet destruction and the reduction of thrombopoietin (TPO) expression in the liver. The mechanisms by which levels of TPO mRNA are regulated in cirrhosis have not been elucidated. In this study, we investigated some possible mechanisms. METHODS: We used three experimental models: bone marrow suppression, acute liver injury and primary cultured hepatocytes. We used northern blots to assess the kinetics of TPO mRNA expression in the livers of irradiated rats (with and without cirrhosis) in acute liver injury and in primary cultured hepatocytes treated with hepatotoxin or cytokines. RESULTS: Although the bone marrow was hypocellular, there was no apparent enhancement of TPO mRNA expression in the irradiated rats with cirrhotic livers compared with the unirradiated rats with cirrhotic livers. There were no conspicuous changes in hepatic TPO mRNA expression between the livers of the control rats and the three models of acute liver injury. There were no conspicuous changes in the levels of TPO mRNA between control hepatocytes and hepatocytes treated with hepatotoxin or cytokines. CONCLUSIONS: Our results suggest that bone marrow is not a regulator of hepatic TPO production in cirrhosis. The reduced TPO mRNA expression found in cirrhotic rats may not result merely from serious cellular damage; it may be associated with cirrhosis-specific regulatory mechanisms for the expression of the TPO gene. Further studies are needed to search for other factors that may induce reduced TPO expression.

Acute Disease↗
PubMed2000

Decreased function of peripheral blood dendritic cells in patients with hepatocellular carcinoma with hepatitis B and C virus infection.

BACKGROUND: Tumour immunity does not seem to be induced effectively in tumour-bearing hosts, including in patients with hepatocellular carcinoma (HCC). One possible reason is that function of dendritic cells (DC) is decreased in such hosts. METHODS: We evaluated T cell stimulatory activity and interleukin (IL)-12 production of DC and interferon (IFN)-gamma and IL-10 production of T cells of peripheral blood from 12 control individuals and 21 patients with chronic hepatitis C virus (HCV) infection (six with chronic hepatitis (CH), eight with liver cirrhosis (LC) and 13 with HCC). Five hepatitis B virus (HBV)-infected patients with HCC were included as a disease control group. The DC were prepared by the culture of T cell-depleted populations of peripheral blood mononuclear cells in the presence of granulocyte-macrophage colony stimulating factor and IL-4 for a total of 11-12 days. The cytokine levels were assayed by ELISA. To test the stimulatory function of DC in T cell proliferation, mytomycin C-treated DC were cultured with allogeneic T cells from a control. RESULTS: When the T cell-stimulatory activity of DC was expressed as stimulation index value of [3H]-thymidine incorporation of T cells, the values were lower in HCV-infected HCC (2.6 +/- 1.8, P < 0.01) than in controls (5.5 +/- 2.0) and CH (5.0 +/- 1.3). Staphylococcus aureus Cowan 1-induced IL-12 production of DC was decreased in HCV-infected HCC (P < 0.001, P < 0.01 and P < 0.05, respectively) compared with controls, CH and LC, while similar amounts of IL-10 were produced in patients and controls. Interleukin-10 and IFN-gamma production of T cells in response to anti-CD3 antibody or IL-12 were equivalent between patient groups and controls, respectively. Similarly decreased DC function and normal T cell response were observed in HBV-infected HCC patients. CONCLUSIONS: These findings suggest that the depressed function of DC is associated with pathogenesis of HCC with HBV or HCV infection.

Adult↗
PubMed2000

Interaction between hyaluronan and CD44 in the development of dimethylnitrosamine-induced liver cirrhosis.

BACKGROUND: A significant increase in serum hyaluronan (HA) levels has been reported in patients with liver cirrhosis. This mechanism is not yet clear, and receptors for HA have not been characterized. In this study, we examined the expression of both HA and its receptors, CD44 and intercellular adhesion molecule-1 (ICAM-1), in dimethylnitrosamine-induced liver cirrhosis. METHODS AND RESULTS: Using biotinylated HA binding protein, HA was detected in the area of periportal fibrosis and around the sinusoidal wall where hepatic fibrosis was developing. Electron microscopy revealed that HA was localized on Ito cells and sinusoidal endothelial cells (SEC). Conversely, CD44, which was only expressed weakly in normal liver, was present in large amounts in cirrhotic liver. The distribution pattern of CD44 was similar to that of HA, however, CD44 was mainly localized on the infiltrating lymphocytes and Kupffer cells. Moreover, CD44 was detected on part of factor VIII-positive SEC. Intercellular adhesion molecule-1, another receptor for HA, was detected on the surface of hepatocytes and around the sinusoidal wall in cirrhotic liver, but its distribution was not accompanied by expression of HA. With respect to CD44 isoforms, the standard form m-RNA predominated in both normal and cirrhotic liver. Variant pMeta-1 mRNA was detected at low levels. CONCLUSIONS: An interaction between HA and CD44 may play a role in the recruitment of numerous infiltrating cells and HA accumulation in hepatic sinusoids. Together with phenotypic changes in the SEC, these results may lead to a disturbance in the elimination of HA during the progression of liver cirrhosis.

Animals↗