Biomedical subjects

K Taguchi

Publications and source records attributed to K Taguchi.

At least 109 records · Page 6Linked to original sources

PubMed1998

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 1: Hemodynamic effects in normal dogs and dogs with acute heart failure.

Cardiovascular effects of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine), a calcium channel blocker, were investigated in anesthetized normal dogs and dogs with acute heart failure (AHF), and compared with those of nitroglycerin (NTG). In open-chest anesthetized dogs, NIC (0.1-10 micrograms/kg/min i.v.) dose-dependently increased cardiac output (CO) and coronary blood flow as well as decreased mean blood pressure (MBP). NIC had no effect on heart rate (HR) or maximum rate of rise of left ventricular pressure (max. dp/dt). In contrast (0.1-10 micrograms/kg/min i.v.) decreased MBP, but did not change the other cardiovascular parameters. NIC and NTG did not prolong PQ, QRS or QTc intervals. In addition, NIC was effective in the presence of dobutamine. In the anesthetized dog model of ischemic AHF induced by coronary ligation, and ischemia/angiotensin II-induced AHF, NIC (1 and 3 micrograms/kg/min i.v.) increased CO and stroke volume, and reduced total peripheral resistance without decreasing HR or cardiac contractility. Furthermore, in the ischemia/angiotension II-induced AHF model, NIC decreased left ventricular end-diastolic pressure (LVEDP). In contrast, NTG (1-10 micrograms/kg/min i.v.) decreased LVEDP in both AHF models; but did not increase CO. These results suggest that NIC improves hemodynamics in dogs with AHF mainly by reducing afterload without adversely affecting the cardiac contractility or conduction system, while NTG exerts its effect on AHF by reducing preload. NIC injection would thus appear to be beneficial in the treatment of AHF.

Acute Disease↗

PubMed1998

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 2: Effect on myocardial metabolism.

The effect of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine) on myocardial metabolism was investigated in an experimental model of ischemic acute heart failure (AHF) induced by coronary ligation in anesthetized dogs. The left anterior descending and/or circumflex coronary ligation decreased coronary sinus blood flow (CBF), maximum rate of rise of left ventricular pressure (max. dp/dt), cardiac output (CO) and stroke volume (SV), and increased left ventricular end-diastolic pressure, indicating the development of AHF. In this ischemic AHF model, NIC (3 micrograms/kg/min i.v. infusion for 15 min) increased CBF, CO and SV, and reduced systemic and coronary artery resistances, resulting in the improvement of AHF. During the effective period, NIC decreased myocardial oxygen consumption and the coronary arterio-venous difference of oxygen content, carbon dioxide pressure and pH. At the same time, NIC did not decrease the lactate extraction. These results suggest that NIC improves hemodynamics and the balance of myocardium oxygen supply and demand in dogs with AHF by means of reducing afterload and dilating coronary artery.

Acute Disease↗

PubMed1998

Protein kinase C does not mediate phenylephrine-induced down-regulation of Madin-Darby canine kidney cell alpha-1B adrenoceptors.

We examined the down-regulation of alpha-1B adrenoceptors in Madin-Darby canine kidney D1 (MDCK) cells with an emphasis on a possible role of protein kinase C. The alpha-1 adrenoceptor agonist phenylephrine (1-100 microM) concentration-dependently down-regulated alpha-1B adrenoceptors in MDCK cells. Down-regulation by 100 microM phenylephrine was detectable after 2 hr and maximal after 8 to 24 hr. The receptor down-regulation was accompanied by a decrease in phenylephrine-stimulated inositol phosphate formation but not by an altered expression of immunodetectable Gq/11 alpha subunits. Even though alpha-1B adrenoceptor and P2 purinergic receptor stimulation promote prostaglandin E2 formation, receptor down-regulation was not prevented by indomethacin (10 microM) treatment but was partly mimicked by treatment with the purinergic receptor agonists adenosine-5'-O-(3-thio)triphosphate and 2-methylthio-ATP (300 microM each). Phorbol-12-myristate-13-acetate (1-100 nM) concentration-dependently down-regulated MDCK alpha-1B adrenoceptors to a greater extent than did phenylephrine. Three protein kinase C inhibitors, H7 (100 microM), staurosporine (100 nM) and KT5926 (1 microM), markedly attenuated receptor down-regulation promoted by phorbol ester but did not affect that by phenylephrine. Two inhibitors of Ca++/calmodulin protein kinase pathways, KT5926 (1 microM) and W-7 (30 microM), also failed to prevent phenylephrine-induced down-regulation of alpha-1B adrenoceptors. We conclude that agonist-induced down-regulation of MDCK cell alpha-1B adrenoceptors is mimicked by a protein kinase C-activating phorbol ester but that the second messenger kinases protein kinase C and Ca++/calmodulin protein kinase do not mediate agonist-induced down-regulation of the alpha-1B adrenoceptor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1997

Light-induced resetting of a mammalian circadian clock is associated with rapid induction of the mPer1 transcript.

To understand how light might entrain a mammalian circadian clock, we examined the effects of light on mPer1, a sequence homolog of Drosophila per, that exhibits robust rhythmic expression in the SCN. mPer1 is rapidly induced by short duration exposure to light at levels sufficient to reset the clock, and dose-response curves reveal that mPer1 induction shows both reciprocity and a strong correlation with phase shifting of the overt rhythm. Thus, in both the phasing of dark expression and the response to light mPer1 is most similar to the Neurospora clock gene frq. Within the SCN there appears to be localization of the induction phenomenon, consistent with the localization of both light-sensitive and light-insensitive oscillators in this circadian center.

Animals↗

PubMed1997

High-performance liquid chromatographic-colorimetric assay for glycine carboxypeptidase activity.

A rapid and sensitive assay method for the determination of glycine carboxypeptidase activity has been reported. This method is based on the monitoring of the absorption at 460 nm of 4-dimethylaminoazobenzene-4'-sulfonyl-Gly-L-Phe, enzymatically formed from the substrate 4-dimethylaminoazobenzene-4'-sulfonyl-Gly-L-Phe-Gly, after separation by high-performance liquid chromatography (HPLC) using a TSK gel ODS-80TM reversed-phase column by isocratic elution. This method is sensitive enough to measure 4-dimethylaminoazobenzene-4'-sulfonyl-Gly-L-Phe at concentrations as low as 1 pmol and yield highly reproducible results and requires less than 7.5 min per sample for separation and quantitation. The pH optimum for glycine carboxypeptidase activity was 4.8 to 5.4. The Km and Vmax values were respectively 21.1 micromol and 3.73 pmol/microg/h with the use of enzyme extract obtained from bovine pituitary. Glycine carboxypeptidase activity was strongly inhibited by Ag+, Cu2+ and p-chloromercuriphenylsulfonic acid. Among the organs examined in a mouse, the highest specific activity of the enzyme was found in testis. The sensitivity and selectivity of this method will aid in efforts to examine the physiological role of this peptidase.

Animals↗

PubMed1997

Adenosquamous carcinoma of the liver: clinicopathologic characteristics and cytokeratin profile.

BACKGROUND: The clinicopathologic characteristics, biologic behavior, and histogenesis of primary adenosquamous carcinoma (ASC) of the liver have yet to be fully clarified. METHODS: Eight cases of ASC of the liver were analyzed both clinicopathologically and immunohistochemically using antibodies of cytokeratin (CK) 7, CK 8, CK 18, CK 19, and CK 903 (CK 5, CK 10, CK 11, and CK 14). The survival curve of the 6 patients with surgically resected ASC was compared with that of the 32 patients with common cholangiocarcinoma (CC). RESULTS: Most ASCs had invasive pathologic features, including venous invasion, lymphatic permeation, and intrahepatic metastases. There were lymph node metastases from 7 tumors (88%), and most of the metastases were adenocarcinoma. All adenocarcinoma (AC) components were positive for both CK 7 and CK 19. The squamous cell carcinoma (SCC) components were positive for CK 7 in all cases but were positive for CK 19 in only 5 cases (62.5%). The ACs were positive for CK 903 in only 3 cases (37.5%), whereas all SCCs were positive for CK 903. Almost all ACs were positive for both CK 8 and CK 18, whereas the SCCs were positive for CK 8 in only 3 cases (37.5%) and for CK 18 in no cases. All 6 patients with surgically resected ASC died of the disease within 1 year postoperatively. Their survival curve was significantly worse than that of the 32 patients with common CC (P < 0.001). The two patients on whom autopsy was performed also died within 1 year after diagnosis. CONCLUSIONS: ASC tended to have more aggressive biologic behavior and a poorer prognosis than common CC. The authors' immunohistochemical analysis of CK expression indicated that most of the ASCs of the liver that were studied developed from a squamous transformation of the preexisting CC.

Aged↗

PubMed1997

Electron microscopic study on nerve terminals during dentin bridge formation after pulpotomy in dog teeth.

This study was designed to examine the relation between pulpal nerves and the differentiation of pulpal cells into preodontoblasts and odontoblasts during the healing process after pulpotomy. A total of 36 upper and lower teeth obtained from six adult dogs were used. The pulp chamber was opened with a sterile diamond bur, the coronal pulp was exposed, and the whole surface of the amputated pulp was capped with calcium hydroxide. The interval between pulpotomy and extraction was 5, 7, 10, 15, 20, 30, 40, 50, and 60 days, and then specimens were examined ultrastructurally. Close contact between fibroblast-like cells/osteoblast-like cells and nerve terminals at the calcification front was observed in the early healing process after pulpotomy, suggesting a close relation between nerve fibers and pulpal cell differentiation.

Animals↗

PubMed1997

In vivo voltammetric studies of the effects of intrathecal morphine on noxious heat stimuli-induced serotonin release in the nucleus raphe magnus of anesthetized rats.

The effects of cutaneous noxious heat stimuli and intrathecal administration of morphine on the oxidation current of 5-hydroxytryptamine (serotonin: 5-HT) in the nucleus raphe magnus (NRM) were examined in anesthetized rats. An oxidation current of 5-HT was seen at 320-340 mV using differential normal pulse voltammetry with nafion-coated carbon fiber electrodes. The signal was decreased by 28.5 +/- 5.7 and by 12.7 +/- 4.1% after cutaneous noxious heat stimuli of 52 and 45 degrees C, respectively. These decreases lasted for 5-10 min. Non-noxious stimuli (37 degrees C) did not affect the 5-HT signal. Intrathecal administration of morphine (2.5, 5.0, 10.0 and 15.0 microg) in the absence of cutaneous stimulation did not change the signal significantly. However, low doses of morphine (2.5 or 5.0 microg, i.t.) potentiated the decrease in the 5-HT signal induced by noxious stimuli, and high doses (10.0 or 15.0 microg, i.t.) attenuated it. Both effects of morphine at low and high doses were antagonized by naloxone (0.5 mg/kg, i.p.). These results indicate that the intrathecal administration of morphine affects the cutaneous noxious heat stimulus-induced decrease of serotonin release in the NRM.

Animals↗

PubMed1997

Cholinergic mechanisms responsible for blood pressure regulation on sympathoexcitatory neurons in the rostral ventrolateral medulla of the rat.

We examined whether reticulospinal sympathoexcitatory neurons in the rostral ventrolateral medulla (RVLM) have muscarinic receptors and ACh inputs, and whether these cholinergic mechanisms on RVLM neurons are involved in the pressor response induced by peripheral administration of physostigmine. Microiontophoretic application of ACh and carbachol enhanced the firing rate of RVLM sympathoexcitatory neurons and the enhancement of RVLM neurons by these cholinoceptor agonists was abolished by the nonselective muscarinic receptor antagonist scopolamine and/or by the M2 muscarinic receptor antagonist methoctramine. Physostigmine and the ACh releaser 3,4-diaminopyridine also enhanced the firing rate of RVLM neurons. Intravenous administration of physostigmine enhanced RVLM sympathoexcitatory neuronal activity and the physostigmine-induced response was reversed by iontophoretic application of scopolamine onto the neurons. These results are consistent with the hypothesis that M2 muscarinic receptors responsible for blood pressure regulation are present on RVLM sympathoexcitatory neurons and these receptors receive ACh inputs. Physostigmine injected systemically may exert a portion of its hypertensive effect through a direct enhancement of cholinergic mechanisms on RVLM sympathoexcitatory neurons.

Acetylcholine↗

PubMed1997

Characterization and management of deep neck infections.

A retrospective review was conducted of 91 patients with deep neck infections to determine the pattern of clinical disease and formulate a management plan. The spaces involved, as determined by clinical, radiologic, and operative findings, were the peritonsillar space (72 patients), parapharyngeal space (eight patients) submandibular space (seven patients), retropharyngeal space (one patient) superficial space (one patient), anterior visceral space (one patient), and visceral vascular space (one patient). Of the 19 patients who did not have a peritonsillar space infection the origin of the infection was found in eight; four of these were odontogenic. Thirty-eight patients required surgical drainage of the abscess. Five patients underwent tracheotomy due to increasing dyspnea. One patient with diabetes mellitus and a past history of myocardial infarction died of unknown cause. All other patients had an uneventful recovery without major complications. The combination of early radiologic diagnosis, effective antimicrobial therapy, and intensive surgical management contributed to the good prognosis.

Abscess↗

PubMed1997

Two transcription factors, E1AF and N-myc, correlate with the invasiveness of neuroblastoma cell lines.

The ets transcription factor E1AF can activate several matrix-degrading metalloproteinase (MMP) genes and is implicated in enhancement of tumor cell invasion. Here we compared the invasive activity of five human neuroblastoma cell lines (TGW, GOTO, SK-N-BE, SK-N-SH and SK-N-AS), which exhibit distinct levels of N-myc amplification, together with the expression of E1AF. Extracellular matrix-degrading proteases and their inhibitor proteins, which play an important role in local invasion, were also analyzed. The activity to invade through reconstituted basement membrane was high in cells (TGW, GOTO, and SK-N-BE) with N-myc amplification, and these cells produced relatively large amounts of E1AF mRNA, correlating with the invasive activities. Of several matrix metalloproteinases (MMPs) and a tissue inhibitor of MMPs (TIMP), only membrane-bound type 1 MMP (MT1-MMP) was specifically detected in N-myc-amplified cells, suggesting a role of MT1-MMP in neuroblastoma cell invasion. MMP-2 (72 kD type IV collagenase), TIMP-1 and TIMP-2 were expressed in all five cell lines. Urokinase-type plasminogen activator was undetectable. These findings indicate that the transcription factors E1AF and N-myc are related to malignant phenotypes of neuroblastoma.

Adenovirus E1A Proteins↗

PubMed1997

Functional outcome and late complications in patients with continent urinary reservoirs.

BACKGROUND: We reviewed the functional outcome and late complication of continent urinary reservoirs (CUR) constructed with a cecocolonic segment, including the Indiana pouch, in 37 patients treated in our clinic. METHODS: The CUR procedure was performed on 37 patients, creating partially detubularized (PD) reservoirs in 9 patients, totally detubularized (TD) reservoirs in 16 patients and reservoirs with an ileal patch (IP) in 12 patients. Continence was achieved by the nipple valve in 10 patients and by ileal plication in 27 patients. The mean follow-up period was 46 months (range, 15 to 87 months). The function of the reservoir was evaluated by measurement of the intrareservoir pressure. RESULTS: Patients with the TD reservoir had less frequent appearance of involuntary, phasic elevation of the intrareservoir pressure (30.8%) than those with the PD reservoir (62.5%). In contrast, this phasic elevation was found in only 1 patient with an IP reservoir. The IP reservoir had the largest capacity accompanied by the lowest maximum intrareservoir pressure. Total incontinence was observed in 2 patients with ileal plication due to disruption of the plicated sutures on the terminal ileum. Frequent difficulty in catheterizing the reservoir was found in 2 patients, and reservoir-ureter reflux was found in 3 renal units. The serum chloride level was significantly elevated after surgery, however, in most patients the levels remained within normal limits. CONCLUSION: Our experience of the outcome and late complications of reservoirs indicates that the cecocolonic reservoir with an ileal patch and stapled ileal plication, i.e., the Indiana pouch, is a better choice for continent urinary diversion for patients who need a cystectomy.

Adult↗

PubMed1997

Malignant melanoma of the uterine cervix: a case report.

We present case of a 57-year-old Japanese woman a 9 cm-size primary malignant melanoma of the uterine cervix. MRI demonstrated a low-signal T1-weighted spin echo image and hyperperfusion indicated by Gd-DTPA enhancement. The sequence analysis of the MTS1/CDK4I gene revealed no deletion or mutation. The results of cytological, pathological, and electron microscopy tests are also presented.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Reconstruction culture system simulating human synovium: a three-dimensional collagen gel culture of synoviocytes.

We developed a reconstruction culture system simulating human synovium to investigate the synoviocytes in a more physiological condition. This system with two types of dishes provided the two separated spaces corresponding to the joint cavity and nutrient vessels. The isolated normal synoviocytes were cultured in type-I collagen gel with a layer-seeded on top in a smaller inner dish with a porous bottom, which was placed in a larger outer dish. We added hyaluronic acid solution to the space on the gel to make an environment close to the physiological joint cavity. The space between the inner and outer dishes was filled with a complete medium to nourish the synoviocytes through the porous filter (Experiment 1). In addition, to examine cell-to-cell interaction, we created a co-culture model by mixing synoviocytes and peripheral blood mononuclear cells in the collagen gel matrix (Experiment 2). In this way we could reconstruct the synovium in vitro. The synoviocytes could survive and maintain their characteristics for four weeks of culture. In Experiment 1, almost all the cells were similar to type B synovial cells by histological, immunohistochemical and electron microscopic observations. In Experiment 2, the spherical cells in abundance of lysosomes like type A synovial cells appeared sporadically in the lining layer. Immunohistochemically, the majority of cultured cells expressed CD68 and matrix metalloproteinase 3. This culture system promises to be of use in investigating the pathogenesis of various joint diseases.

Adolescent↗

PubMed1997

Effects of cAMP and cGMP on L-type calcium channel currents in rat mesenteric artery cells.

L-type Ca2+ channel currents in cultured rat mesenteric artery smooth muscle cells were recorded by the cell-attached patch-clamp technique. Depolarizing voltage steps from a holding potential of -40 mV elicited voltage-dependent inward Ba2+ currents. The inward currents were inhibited by nifedipine (10 microM) but enhanced by Bay K 8644 (5 microM), which suggests that the inward currents are carried almost exclusively by L-type Ca2+ channels. Application of dibutyryl cAMP (0.1-1 microM) and forskolin (0.01-1 microM) enhanced the activity of these Ca2+ channels. The dibutyryl cAMP induced enhancement of Ca2+ channels was antagonized by the serine/threonine kinase inhibitor H-8 (1 microM). Application of 8-bromo-cGMP (0.01-1 microM) and the cGMP inducer nitroglycerin (0.01-1 microM) inhibited the activity of these Ca2+ channels, and the inhibition of channel activity induced by 8-bromo-cGMP was antagonized by the serine/threonine kinase inhibitor H-8 (1 microM). These results suggest that in rat mesenteric artery cells, the L-type Ca2+ channel current is enhanced by a rise in intracellular cAMP levels and suppressed by a rise in intracellular cGMP levels. Furthermore, cGMP-induced Ca2+ channel inhibition may play a role in the expression of the nitric oxide-mediated vasodilating action of drugs such as nitroglycerin and atrial natriuretic peptide.

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

PubMed1997

A clinical analysis of malignant schwannoma.

In this study, we reviewed the clinical features of 11 patients with malignant schwannoma who were treated in our institute. Five patients had coexistent von Recklinghausen's disease and one of them showed multifocal occurrence. Patients with the centrally located tumors had a poorer prognosis than those with the others. The overall 3-year survival rate was 36%; 40% in patients with von Recklinghausen's disease and 33% in the others. At the time of the last follow-up, 9 patients had died of the tumor, one continued to be tumor free, and one was alive with tumor. Postoperative local recurrence developed in 5 patients (45%); 4 out of 6 patients (67%) who underwent a marginal excision and one out of 3 (33%) who underwent primary amputation. There was no local recurrence in patients after a wide excision with at least 3 cm of normal tissue removed surrounding the tumor in all directions. Nine patients (82%) developed pulmonary metastasis. The effect of adjuvant chemotherapy was not clear in this study. The high risk of pulmonary metastasis in this disease indicates the necessity of more effective adjuvant chemotherapy.

Adolescent↗

PubMed1997

Effects of tamsulosin metabolites at alpha-1 adrenoceptor subtypes.

We have investigated the affinity and selectivity of tamsulosin and its metabolites, M1, M2, M3, M4 and AM1, at the tissue and the cloned alpha-1 adrenoceptor subtypes in the radioligand binding and the functional studies. In the radioligand binding studies, the compounds competed for [3H]prazosin binding to the rat liver and kidney alpha-1 adrenoceptors, with the rank order of potency tamsulosin approximately M4 > M1 > M2 approximately M3 > > AM1 with the latter having a negligible affinity. All compounds differentiated cloned alpha-1 adrenoceptor subtypes with the rank order of potency of alpha-1A > or = alpha-1D > alpha-1B, except for M4 which had the highest affinity for the alpha-1D adrenoceptor. The compounds also concentration-dependently antagonized phenylephrine-induced contractions in the rabbit aorta and prostate. The resulting apparent pA2 values were very similar to those at the cloned rat alpha-1A adrenoceptor. We conclude that most tamsulosin metabolites are high potency antagonists at the alpha-1 adrenoceptors and retain the alpha-1A over the alpha-1B adrenoceptor selectivity of tamsulosin.

Adrenergic alpha-Antagonists↗

PubMed1997

Vestibulo-ocular reflex and visual vestibulo-ocular reflex during sinusoidal rotation in children.

To clarify the relationship between vestibular and visual (optokinetic) stimuli in normal children, we investigated the vestibulo-ocular reflex (VOR) and visual VOR (VVOR). The subjects were 20 healthy children aged 3-6 years and 24 healthy adults aged 21-29 years. The VOR gains and phase were measured under two visual conditions: with eyes open in complete darkness and with eyes open in a lighted optokinetic drum. In both visual conditions, phase did not significantly differ between children and adults. In the dark, children presented a significantly larger gain than that of adults. In the optokinetic drum, however, the gain values of the children were almost the same as in adults. We suggest that the large VOR gain values of children may be due to immaturity of the inhibitory regulation system of the VOR.

Adult↗