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Biomedical subjects

H Katoh

Publications and source records attributed to H Katoh.

At least 109 records · Page 6Linked to original sources
PubMed2000

Contribution of endogenous nitric oxide to basal vasomotor tone of peripheral vessels and plasma B-type natriuretic peptide levels in patients with congestive heart failure.

OBJECTIVES: We examined whether a relationship exists between the vasoconstrictive response to endogenous nitric oxide (NO) synthesis inhibition and the severity of heart failure in patients with congestive heart failure (CHF). BACKGROUND: Controversy exists as to whether the vasoconstrictive response to NO synthesis inhibition in patients with CHF is comparable to that in normal subjects or is enhanced. METHODS: Forearm blood flow (FBF) and calculated forearm vascular conductance (FVC) were obtained using plethysmography before and after administration of the NO synthesis inhibitor L-NMMA (NG-monomethyl-L-arginine) in 40 patients with CHF due to dilated cardiomyopathy and in 16 normal control subjects. Basal plasma B-type natriuretic peptide (BNP) and nitric oxide concentrations were measured in all subjects. RESULTS: Plasma BNP and nitrite/nitrate (NOx) levels in the patients group were significantly greater and baseline FBF was significantly less. Administration of L-NMMA significantly decreased FBF and FVC in both groups. The percent changes in FBF (%FBF) and FVC (%FVC) from the baseline after L-NMMA correlated significantly with plasma BNP level (%FBF: r = 0.72; %FVC: r = 0.76; both p < 0.001). Percent changes in both FBF and FVC were greater in patients with BNP > or = 100 pg/ml than in normal subjects; however, in patients with BNP < 100 pg/ml they were comparable to those in normal subjects. CONCLUSIONS: Vasoconstrictive response to L-NMMA in patients with CHF was preserved or enhanced in proportion to the basal plasma BNP level, indicating a close relationship between the contribution of endogenous NO to basal vasomotor tone and the severity of heart failure.

Adult↗
PubMed2000

Diagnostic implications of elevated levels of smooth-muscle myosin heavy-chain protein in acute aortic dissection. The smooth muscle myosin heavy chain study.

BACKGROUND: A rapid 30-minute assay of circulating smooth-muscle myosin heavy-chain protein has been developed as a biochemical diagnostic tool for aortic dissection. OBJECTIVE: To determine the sensitivity and specificity of this assay. DESIGN: Cross-sectional study. SETTING: 8 major cardiovascular centers in Japan. PATIENTS: 95 patients with acute aortic dissection, 48 patients with acute myocardial infarction, and 131 healthy volunteers. MEASUREMENTS: Levels of circulating smooth-muscle myosin heavy-chain protein. RESULTS: Patients with acute aortic dissection who presented within 3 hours after onset had elevated levels of circulating smooth-muscle myosin heavy-chain protein. In these patients, the assay had a sensitivity of 90.9%, a specificity of 98% compared with healthy volunteers, and a specificity of 83% compared with patients who had acute myocardial infarction; the clinical decision limit was 2.5 microgram/L. All patients with proximal lesions had elevated levels of smooth-muscle myosin heavy-chain protein, and only patients with distal lesions had decreased levels (<2.5 microgram/L). CONCLUSIONS: Levels of smooth-muscle myosin heavy-chain protein can be used to diagnose aortic dissection soon after symptom onset. The assay had the greatest diagnostic value in patients with proximal lesions.

Aged↗
PubMed2000

Receptor isoform-specific interaction of prostaglandin EP3 receptor with muskelin.

By using the yeast two-hybrid system, muskelin was found to bind with the carboxy-terminal tail of the prostaglandin EP3 receptor alpha isoform but not with either the beta or gamma isoform. A direct interaction between the carboxy-terminal tail of the alpha isoform and muskelin was confirmed in vitro using recombinant fusion proteins. Analysis by confocal microscopy indicated that the isoform and muskelin were distributed at the plasma membrane in transfected cells. When the isoform was stimulated by agonist, the receptor was internalized in the cells expressing the receptor alone, but this internalization was partially inhibited by the cotransfection with muskelin. Furthermore, muskelin enhanced the Gi activity of the isoform. Thus, muskelin appears to be an isoform-specific anchoring protein for the EP3 receptor.

Animals↗
PubMed2000

Transmission of information from cardiac dihydropyridine receptor to ryanodine receptor: evidence from BayK 8644 effects on resting Ca(2+) sparks.

Coupling between L-type Ca(2+) channels (dihydropyridine receptors, DHPRs) and ryanodine receptors (RyRs) plays a pivotal role in excitation-contraction (E-C) coupling in cardiac myocytes, and Ca(2+) influx is generally accepted as the trigger of sarcoplasmic reticulum (SR) Ca(2+) release. The L-type Ca(2+) channel agonist BayK 8644 (BayK) has also been reported to alter RyR gating via a functional linkage between DHPR and RyR, independent of Ca(2+) influx. Here, the effect of rapid BayK application on resting RyR gating in intact ferret ventricular myocytes was measured as Ca(2+) spark frequency (CaSpF) by confocal microscopy and fluo 3. BayK increased resting CaSpF by 401+/-15% within 10 seconds in Ca(2+)-free solution, and depolarization had no additional effect. The effect of BayK on CaSpF was dose-dependent, but even 50 nmol/L BayK induced a rapid 245+/-12% increase in CaSpF. Nifedipine (5 micromol/L) had no effect by itself on CaSpF, but it abolished the BayK effect (presumably by competitive inhibition at the DHPR). The nondihydropyridine Ca(2+) channel agonist FPL-64176 (1 micromol/L) did not alter CaSpF (despite rapid and potent enhancement of Ca(2+) current, I(Ca)). In striking contrast to the very rapid and depolarization-independent effect of BayK on CaSpF, BayK increased I(Ca) only slowly (tau=18 seconds), and the effect was greatly accelerated by depolarization. We conclude that in ferret ventricular myocytes, BayK effects on I(Ca) and CaSpF both require drug binding to the DHPR, but postreceptor pathways may diverge in transmission to the gating of the L-type Ca(2+) channel and RyR.

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

Immunohistochemical localization of prostaglandin EP3 receptor in the rat nervous system.

The prostaglandin EP3 receptor (EP3R) subtype is believed to mediate large portions of diverse physiologic actions of prostaglandin E2 in the nervous system. However, the distribution of EP3R protein has not yet been unveiled in the peripheral or central nervous systems. The authors raised a polyclonal antibody against an amino-terminal portion of rat EP3R that recognized specifically the receptor protein. In this study, immunoblotting analysis with this antibody showed several immunoreactive bands with different molecular weights in rat brain extracts and in membrane fractions of recombinant EP3R-expressing culture cells, and treatment with N-glycosidase shifted those immunoreactive bands to an apparently single band with a lower molecular weight, suggesting that EP3R proteins are modified posttranslationally with carbohydrate moieties of various sizes. The authors performed immunohistochemical investigation of EP3R in the rat brain, spinal cord, and peripheral ganglia by using the antibody. EP3R-like immunoreactivity was observed in many and discrete regions of the rostrocaudal axis of the nervous system. The signals were particularly strong in the anterior, intralaminar, and midline thalamic nuclear groups; the median preoptic nucleus; the medial mammillary nucleus; the superior colliculus; the periaqueductal gray; the lateral parabrachial nucleus; the nucleus of the solitary tract; and laminae I and II of the medullary and spinal dorsal horns. Sensory ganglia, such as the trigeminal, dorsal root, and nodose ganglia, contained many immunopositive neurons. Neuronal cells in the locus coeruleus and raphe nuclei exhibited EP3R-like immunoreactivity. This suggests that EP3R plays regulatory roles in the noradrenergic and serotonergic monoamine systems. Autonomic preganglionic nuclei, such as the dorsal motor nucleus of the vagus nerve, the spinal intermediolateral nucleus, and the sacral parasympathetic nucleus, also contained neuronal cell bodies with the immunoreactivity, implying modulatory functions of EP3R in the central autonomic nervous system. The characteristic distribution of EP3R provides valuable information on the mechanisms for various physiologic actions of prostaglandin E2 in the central and peripheral nervous systems.

Animals↗
PubMed2000

Different membrane targeting of prostaglandin EP3 receptor isoforms dependent on their carboxy-terminal tail structures.

Mouse prostaglandin EP3 receptor consists of three isoforms, EP3alpha, beta and gamma, with different carboxy-terminal tails. To assess the role of their carboxy-terminal tails in membrane targeting, we examined subcellular localization of myc-tagged EP3 isoforms expressed in MDCK cells. Two isoforms, EP3alpha and EP3beta, were localized in the intracellular compartment but not in the plasma membrane, while the EP3gamma isoform was found in the lateral plasma membrane and in part in the intracellular compartment. Mutant EP3 receptor lacking the carboxy-terminal tail was localized in the intracellular compartment but not in the plasma membrane. Thus, EP3 isoforms differ in subcellular targeting, and the carboxy-terminal tails play an important role in determination of the membrane targeting of EP3 receptor.

Animals↗
PubMed2000

The timing of GM-CSF expression plasmid administration influences the Th1/Th2 response induced by an HIV-1-specific DNA vaccine.

The mechanism of immune activation induced by a plasmid-encoding GM-CSF (pGM-CSF), administered in combination with a DNA vaccine encoding the envelope of HIV, was studied. Injecting pGM-CSF i.m. into mice 3 days before DNA vaccination primarily induced a Th2 response. Simultaneous administration of the DNA vaccine plus pGM-CSF activated both a Th1 and a Th2 response. When the plasmid was injected 3 days after DNA vaccination, enhancement of Th1 immunity predominated. These results suggest that the timing of cytokine expression determines the phenotype of the resultant Th response. After 3 days of pGM-CSF injection, the increased percentages of CD11c+, CD8+ cells were observed in the regional lymph nodes. In addition, many infiltrated cells, including S-100 protein-positive cells, were found in the pGM-CSF-injected tissue. The importance of these S-100+ cells or both CD8+ and CD11c+ cells, especially that of dendritic cells (DCs), was also studied. DCs derived from bone marrow and cultured in RPMI 1640 medium containing IL-4 and GM-CSF were incubated with DNA vaccine and then transferred into naive mice. Mice receiving DCs showed strong HIV-1-specific Th2 immune responses. Our results suggest that DCs play important roles in the activation or modification of the Th2-type immune response induced by DNA vaccination.

AIDS Vaccines↗
PubMed2000

Molecular decipherment of Rho effector pathways regulating tight-junction permeability.

We reported recently that the activation of RhoA induced an increase in transepithelial electrical resistance (TER). To clarify effectors of Rho for this RhoA-induced regulation of tight-junction permeability, we introduced two effector-loop mutants of constitutively active RhoA(V14), RhoA(V14/L40) and RhoA(V14/C42), into Mardin-Darby canine kidney cells in an isopropyl beta-D-thiogalactoside-inducible expression system. RhoA(V14) and the two effector-loop mutants interacted in vitro with the Rho-binding domain of Rho-associated kinase, ROKalpha. Next we examined two parameters of Rho functions, stress-fibre formation and TER elevation, induced by RhoA(V14). Stress-fibre formation was induced by RhoA(V14/C42) but not by RhoA(V14/L40). On the other hand, TER elevation was induced by neither RhoA(V14/L40) nor RhoA(V14/C42). RhoA-associated kinase inhibitor, Y-27632, inhibited both stress-fibre formation and TER elevation induced by RhoA(V14). These results demonstrated that RhoA-induced regulation of tight-junction permeability is mediated by Rho-associated kinase and at least one other unidentified effector, the coupling to RhoA being disrupted by mutation at position 40 or 42 in the effector loop.

Animals↗
PubMed2000

The synergistic effect of high K+ and hypoxia on extracellular concentrations of neuroactive amino acid in hippocampus.

In the present study, we examined extracellular concentrations of glutamate (Glu) in hypoxia using ringer solution with a high potassium (K+) level using microdialysis. Based on our findings, we hypothesized that the concentration of extracellular K+ caused a greater efflux of Glu. We used male SD rats and separated them into 3 groups based on the K+ concentration of Ringer solution (RS), consisting of normal (4 mM), 40 mM and 150 mM groups. We stereotactically inserted the microdialysis probe into the hippocampus, and perfused the RS for 60 min before imposing hypoxia. Subsequently, while perfusing RS, hypoxia (7% O2 + 93% N2 gas) was induced in all 3 groups for 20 min. In the normal and 40 mM of K+ concentration groups, the Glu level did not increase, but in the 150 mM of K+ concentration group, the Glu level increased while being perfused with RS and a larger increase in Glu was observed after inducing hypoxia. This result suggests that the extracellular concentration of K+ plays a role in the mechanism of increased neuronal vulnerability caused by hypoxia after TBI.

Animals↗
PubMed2000

Reconstruction after total pharyngolaryngoesophagectomy. Comparison of elongated stomach roll with microvascular anastomosis with gastric pull up reconstruction or something like that.

BACKGROUND: We have performed total pharyngolaryngoesophagectomy in case of double cancer, head-neck and thoracic esophageal cancer, or cervical esophageal cancer that extended down to the level of aortic arch. The procedure is very challenging. METHODS: From April 1984 to May 1998, 14 patients underwent the procedures for double cancer of head-neck and thoracic esophagus (n=10), hypopharyngeal or cervical esophageal cancer (n=3), and synchronous esophageal cancer (n=1). The grafts used were whole stomach (n=6), elongated stomach roll (n=5), and stomach roll with free jejunum (n=3). The routes of reconstruction were posterior mediastinum (n=10), antesternal (n=3), and retrosternal (n=1). RESULTS: Elongated stomach roll with microvascular anastomoses was long enough for reconstruction and the blood supply of the graft was sufficient. There was no fatal complication in this procedure. Oral feeding was achieved in 13 (93%) patients. CONCLUSIONS: The elongated stomach roll with microvascular anastomosis is efficient and the placement of the conduit in the posterior mediastinum is recommended to allow a better alimentary comfort in total pharyngolaryngoesophagectomy.

Adult↗
PubMed2000

Acquired ileal diverticulum: an unusual bleeding source.

Acquired ileal diverticulum is an uncommon condition and diagnosis is often difficult when bleeding occurs from this source. Here we describe two cases of ileal diverticulum with massive bleeding. Both patients presented with anal bleeding, but upper and lower gastrointestinal endoscopy did not reveal the source. Selective visceral angiography finally detected bleeding lesions in the terminal ileum. Surgical resection was performed in both patients, confirming that the bleeding arose from diverticula less than 1 cm in size. In patients with obscure gastrointestinal bleeding, an ileal diverticulum should be considered, and selective visceral angiography should be performed for precise diagnosis.

Aged↗
PubMed2000

Nonfunctioning endocrine tumor of the pancreas with extrapancreatic growth and cyst formation: report of a case.

We report a case of nonfunctioning endocrine tumor of the pancreas with extrapancreatic growth and cyst formation. A 48-year-old woman was admitted to our hospital with an upper abdominal mass, which was detected during a routine medical checkup. The preoperative diagnosis was a solid cystic tumor of the pancreas. The tumor, which measured about 7cm in diameter, arose from the head of the pancreas and had a thin stalk, measuring about 1 cm in diameter. The histopathological diagnosis was a malignant nonfunctioning endocrine tumor of the pancreas. Cyst formation occurred in 67% of the reported cases with extrapancreatic growth in Japan. It is speculated that the cyst formation in this disease is related to the large size of the tumor and to the extrapancreatic growth.

Abdominal Pain↗
PubMed2000

Is median sternotomy invasive? A comparison between minimally invasive direct coronary artery bypass and off-pump bypass.

Although minimally invasive direct coronary artery bypass (MIDCAB) eliminates the need for median sternotomy and cardiopulmonary bypass, its indications are limited. Conversely, coronary artery bypass without cardiopulmonary bypass (off-pump bypass) enables complete surgical revascularization under an optimal surgical field established by median sternotomy, even if patients have multivessel disease. The present study was designed to determine the invasiveness of median sternotomy by comparing 11 patients who underwent MIDCAB and 5 who underwent off-pump bypass between May 1997 and April 1998. There were no significant differences between the MIDCAB group and the off-pump group in age, being 57 +/- 11 vs 66 +/- 8 years old, the operative time, being 321 +/- 149 vs 441 +/- 205 min, the number of grafts, being 1.0 vs 1.4/patient, peak creatine kinase (CK) values, being 662 +/- 436 vs 609 +/- 56 IU/l, the peak CK-muscle-brain values, being 12 +/- 9 vs 16 +/- 5 IU/l, and the postoperative blood loss, being 369 +/- 198 vs 541 +/- 204 ml. Although there was no significant difference in peak C-reactive protein, at 17 +/- 5 vs 20 +/- 2 mg/dl, the periods declining within the normal ranges were shorter in the MIDCAB group than in the off-pump group, at 7 +/- 1 vs 15 +/- 2 days (P > 0.01). The hospital stay was almost the same in both groups, at 16 +/- 8 vs 26 +/- 14 days. These findings suggest that off-pump bypass is more invasive than MIDCAB, which may be attributed to the median sternotomy.

Aged↗
PubMed2000

Cystic schwannoma of the orbit: case report.

BACKGROUND: Cystic lesions of the orbit have diverse clinical findings and histopathological features. We report an orbital schwannoma composed of a single cyst. CASE DESCRIPTION: A 62-year-old woman with an intraconal cystic tumor in the left orbital cavity is described. The cystic tumor was totally removed and the pathological diagnosis of the cyst wall was schwannoma composed of both Antoni type A and B. CONCLUSIONS: A rare case of cystic schwannoma of the orbit is reported. This case may contribute to an improved preoperative differential diagnosis for cystic lesions of the orbit.

Cysts↗
PubMed2000

Monoclonal antibodies to plasma high density lipoprotein (HDL) of eel (Anguilla japonica).

Six week-old female mice (Balb/c) injected intraperitonealy with 50 micrograms of eel high density lipoprotein (HDL) emulsified with equal volume of adjuvant three times every two weeks. Three weeks after the third injection, hyperimmunized mice were boosted by injection of 100 micrograms of HDL. After 5 days, the best responding mouse to injected HDL was sacrificed, and spleen cells were fused with mouse myeloma cells (Sp2/O-Ag14), and hybridomas were cultured in a selection medium. Monoclonal antibodies specific to apolipoprotein A-I or A-II (apoA-I or apoA-II) of HDL were obtained by cloning and recloning the hybridomas. Eighteen monoclonal antibodies specific to apoA-I and/or apoApII were isolated. Antibodies in the culture medium were purified by a HiTrap Protein G or an eel-HDL column. These purified antibodies belong to the subclass IgG1. The monoclonal antibodies specific to eel apoA-I and apoA-II secreted by clone 10D12 and 2G3, respectively, interact with serum proteins of some fish species such as red-sea bream and carp. The anti-eel apoA-I antibody of 10D12 did not bind to serum proteins of rat, rabbit, and chicken, while the anti-eel apoA-II of 2G3 antibody did.

Amino Acid Sequence↗
PubMed2000

Atrium as a source of brain natriuretic polypeptide in patients with atrial fibrillation.

BACKGROUND: Plasma brain natriuretic polypeptide (BNP) levels have been used as biochemical markers of systolic left ventricular (LV) dysfunction. Although in vitro studies have shown the existence of BNP messenger RNA in the atria, the main production site of BNP is believed to be the ventricle. The hypothesis that the atrium could be a source of BNP was examined in patients with lone atrial fibrillation (AF), the most common type of sustained arrhythmia. METHODS AND RESULTS: We studied 16 controls and 21 patients with lone AF. Plasma samples for BNP were selectively and serially obtained from the aorta, anterior interventricular vein (AIV), and coronary sinus (CS). Atrial natriuretic polypeptide (ANP) levels were also measured to determine whether the CS samples contained significant amounts of atrial venous drainage. Of the 3 sample locations, the CS had the greatest ANP levels, confirming transcatheter sampling position accuracy. BNP levels were significantly greater in the CS than AIV in the patients with AF (279 +/- 226 v 126 +/- 97 pg/mL; P < .01). Consequently, plasma BNP levels were also greater in the patients with AF than controls (103 +/- 90 v 5 +/- 2 pg/mL; P < .001). LV ejection fraction was significantly less in patients with AF than control patients. Atrial production of BNP decreased significantly after successful DC cardioversion of AF in the 5 restudied patients (182 +/- 139 v 59 +/- 64 pg/mL; P < .05). CONCLUSION: The data suggest that AF is a condition in which BNP is produced in the atrium itself.

Adult↗