Biomedical subjects

H Tachibana

Publications and source records attributed to H Tachibana.

At least 37 records · Page 2Linked to original sources

PubMed2001

Protection of hamsters from amebic liver abscess formation by immunization with the 150- and 170-kDa surface antigens of Entamoeba histolytica.

A monoclonal antibody, EH3015, prevents in vitro adherence of Entamoeba histolytica trophozoites to mammalian cells and inhibits amebic liver abscess formation in hamsters. By immunoaffinity chromatography with the monoclonal antibody, purified E. histolytica antigens with molecular masses of 150 and 170 kDa under non-reduced conditions were obtained. Hamsters were immunized with these antigens (group I) or with fractions further purified by polyacrylamide gel electrophoresis (group II). Pooled immune sera from the two groups inhibited in vitro amebic adherence to Chinese hamster ovary cells by 98% at 1:10 dilutions. The immunized hamsters were challenged by the intrahepatic injection of E. histolytica trophozoites. Complete protection from abscess formation was observed in 38% of hamsters in group I and 67% in group II, whereas all control hamsters inoculated only with adjuvant developed amebic liver abscesses. In the immunized hamsters, the abscesses in the two groups were significantly smaller than in the controls. These results demonstrate that the E. histolytica antigens are possible vaccine candidates for amebiasis.

Animals↗

PubMed2001

Molecular characterization of Cryptosporidium isolates obtained from human and bovine infections in Japan.

Cryptosporidium oocysts, morphologically identified as Cryptosporidium parvum, were isolated from 22 human and 14 bovine cases in Japan, and were genotyped by means of a PCR/RFLP analysis of the polythreonine gene. DNA profiles of human isolates gave three distinct genotypes, namely an anthroponotic genotype 1, zoonotic genotype 2 and a new genotype. Isolates from bovine samples gave zoonotic genotype 2. The unusual genotype of Cryptosporidium was isolated from the feces of three immunologically healthy adults, and was further characterized by the sequence analysis of the 18S rRNA gene. The third genotype was identified as Crypto sporidium meleagridis, demonstrating that C. meleagridis, which occurs worldwide, has the potential to infect humans regardless of their immunological condition.

Animals↗

PubMed2001

Effect of thromboxane A2 (TXA2) synthase inhibitor and TXA2 receptor antagonist alone and in combination on antigen-induced bronchoconstriction in guinea pigs.

Thromboxane A2 (TXA2) causes bronchoconstriction and bronchial hyperresponsiveness. Two types of TXA2 modifiers, one synthase inhibitor and one receptor antagonist, are widely used for the treatment of asthma in Japan. Although the target of TXA2 modifiers is to inhibit bioactivity of TXA2, the pharmacological properties are somewhat different between these drugs. We studied the inhibitory effects of the TXA2 synthase inhibitor CS-518 and the TXA2 receptor antagonist S-1452 alone and in combination on antigen-induced bronchoconstriction in passively sensitized guinea pigs treated with diphenhydramine. Both CS-518 and S-1452 inhibited the antigen-induced bronchoconstriction dose-dependently with the plateau. The combination of these drugs at the maximal inhibitory doses did not have any more effect compared with each single dosing. The combination at the submaximal doses tended to show an additive effect, but the effect was not significant. These findings suggest that other prostanoids such as PGE2, PGI2, PGD2 and PGF2alpha may not take an important role in the antiasthmatic effects of TXA2 modifiers.

Animals↗

PubMed2001

Recognition memory in normal aging and Parkinson's disease: behavioral and electrophysiologic measures.

To assess effects of normal aging and Parkinson's disease (PD) on recognition memory, we examined the N400 component of event-related potentials (ERPs) and behavioral measures during a recognition memory task in 17 normal young subjects, 17 normal elderly subjects, and 17 patients with PD. To elicit ERPs, some words were repeated immediately after initial presentation (at lag 0), while others were repeated after one intervening word (at lag 1) or at lag 6. Subjects were requested to push a button with the right thumb upon first presentation of a word and with the left thumb upon repeat presentation. Compared to the normal young subjects, normal elderly subjects showed reduced accuracy in recognizing repeated words at lags 1 and 6. Compared to the normal elderly group, PD patients showed decreased accuracy in recognizing lag 6 repetition. N400 amplitude did not differ between the two normal groups, while PD patients showed lower N400 amplitudes than normal elderly subjects. The N400 in the young group showed attenuation for lags 0, 1 and 6 repetitions, while attenuations in the elderly group and the PD group were noted only for lags 0 and 1 repetitions. These data suggest intact immediate but impaired delayed recognition memory in aging and in PD. In addition, recognition memory deficits in PD may result, at least partly from the impairment of context integration process.

Acoustic Stimulation↗

PubMed2001

A tea catechin suppresses the expression of the high-affinity IgE receptor Fc epsilon RI in human basophilic KU812 cells.

Human basophilic KU812 cells express the high-affinity IgE receptor Fc epsilon RI, which plays a central role in the IgE-mediated allergic response. The effect of several major tea catechins, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate (EGCg), on the cell surface expression of Fc epsilon RI in KU812 cells was studied. Flow cytometric analysis showed that only EGCg was able to decrease the cell surface expression of Fc epsilon RI after a 24 h treatment in a dose-dependent manner. Moreover, immunoblot analysis revealed that the total cellular expression of the Fc epsilon RI alpha chain decreased upon treatment with EGCg. Fc epsilon RI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. KU812 cells treated with EGCg expressed lower levels of Fc epsilon RI alpha and gamma mRNA than nontreated cells. These results suggest that EGCg has an ability to down-regulate Fc epsilon RI expression, and this suppressive effect may be due to the down-regulation of Fc epsilon RI alpha and gamma mRNA levels.

Basophils↗

PubMed2001

Characterization of increased cough sensitivity after antigen challenge in guinea pigs.

Increased sensitivity of cough reflex is a fundamental feature of bronchodilator resistant non-productive cough associated with eosinophilic tracheobronchitis. Our hypothesis is that cough sensitivity is increased by airway allergic reaction characterized by airway eosinophilic inflammation. The aim of this study was to elucidate the hypothesis and clarify the characteristics of the increased cough sensitivity. Number of coughs elicited by inhalation of increasing concentrations of capsaicin (10-8, 10-6 and 10-4 M) was counted 24 h after an aerosolized antigen or saline in actively sensitized or non-sensitized (naive) conscious guinea pigs and then bronchoalveolar lavage was performed. The cough response was also measured 1 day before and 1, 2, 3, 5 and 7 days after an aerosolized antigen challenge in sensitized or naive animals. In addition, effect of procaterol (0.1 mg/kg), atropine (1 or 10 mg/kg), phosphoramidon (2.5 mg/kg) given intraperitoneally 30 min before the capsaicin challenge or capsaicin desensitization on the cough response was examined. Furthermore, the thromboxane A2 (TXA2) receptor antagonist S-1452 in a dose of 0.01 or 0.1 mg/kg or vehicle (saline) was given intraperitoneally at 24 and 1 h before the measurement of cough response. Number of coughs caused by capsaicin was extremely increased 24 h after an antigen challenge in sensitized guinea pigs compared with a saline or an antigen challenge in naive animals or a saline challenge in sensitized animals. The increased cough response disappeared at 3-7 days after the antigen challenge. Eosinophils in bronchoalveolar lavage fluid obtained after the measurement of capsaicin-induced coughs, which was performed 24 h after the antigen challenge, were significantly increased in sensitized guinea pigs. The eosinophil count was significantly correlated to the number of capsaicin-induced coughs. Procaterol or atropine did not alter the antigen-induced increase of cough sensitivity, whereas atropine did reduce the cough response in naive animals. Phosphoramidon increased the number of capsaicin-induced coughs in naive guinea pigs but not in sensitized and antigen-challenged animals. Capsaicin desensitization decreased the cough response in both antigen-challenged sensitized guinea pigs and naive animals. S-1452 reduced the antigen-induced increase of cough response in sensitized guinea pigs, but not in naive animals. Airway allergy accompanied with airway eosinophilia induces transient increase in cough sensitivity, which is not mediated by bronchoconstriction. The increased cough sensitivity may result in part from inactivation of neutral endopeptidase and TXA2, one of the inflammatory mediators.

Allergens↗

PubMed2001

Effects of suplatast tosilate, a new type of anti-allergic agent, on airway cough hypersensitivity induced by airway allergy in guinea-pigs.

BACKGROUND: Cough receptor hypersensitivity is a fundamental feature of some conditions presenting with chronic non-productive cough. Suplatast tosilate, an anti-allergic agent, is a T helper (Th)2 cytokine inhibitor that inhibits the synthesis of interleukin (IL)-4, IL-5, immunoglobulin (Ig)E production, and local eosinophil accumulation. OBJECTIVE: The purpose of this study was to investigate the effect of suplatast on antigen-induced airway cough hypersensitivity and eosinophil infiltration into the airway. METHODS: Number of coughs elicited by inhalation of increasing concentrations of capsaicin (10-8, 10-6 and 10-4 M) was counted 24 h after an antigen challenge in conscious guinea-pigs and then bronchoalveolar lavage was performed. We investigated the effect of single (before antigen challenge or capsaicin provocation) or repetitive treatment with intraperitoneal suplatast at a dose of 10 or 30 mg/kg on antigen-induced cough hypersensitivity. RESULTS: Twenty-four hours after antigen challenge, guinea-pigs developed an increase in cough receptor sensitivity to inhaled capsaicin and eosinophil infiltration in the airways. After a 2-week treatment with suplatast, but not after only a single treatment before antigen challenge or capsaicin provocation, the antigen-induced early phase bronchoconstriction, cough hypersensitivity, and airway eosinophilia were inhibited in a dose-dependent manner. CONCLUSION: These results indicate that suplatast inhibits airway cough hypersensitivity underlying allergic eosinophilic inflammation.

Airway Resistance↗

PubMed2001

Dietary gamma-linolenic acid dose-dependently modifies fatty acid composition and immune parameters in rats.

gamma-linolenic acid (GLA) has been reported to improve several inflammatory disorders through regulation of eicosanoid production. However, since GLA is a precursor of arachidonic acid, it may bring about increasing tissue arachidonic acid levels with subsequent pro-inflammatory events. To explore this possibility, we examined the effect of high-dose GLA acid on the fatty acid profile of immune cells, leukotriene B4 production by peritoneal exudate cells and immunoglobulin productivity of mesenteric lymph node lymphocytes of Sprague-Dawley rats. Male rats were fed 10% fat diets containing graded levels, 0, 20, 40 and 60% of GLA for 3 weeks. The results showed the distinction in activity of metabolizing GLA between immune cells and liver. Thus, in immune cells such as mesenteric lymph node and spleen lymphocytes and peritoneal exudate cells, more dihomo-gamma-linolenic acid was found than in the liver. Leukotriene B4 production by peritoneal exudate cells was significantly suppressed when fed the highest level of GLA suggesting a lower risk of allergic reaction. Moreover, immunoglobulin productivity in mesenteric lymph node lymphocytes was promoted by dietary GLA. The present study indicates that a high dose of GLA may exert anti-inflammatory effects through suppression of leukotriene B4 release and strengthening of gut immune system, thus ameliorating allergic reaction.

Animals↗

PubMed2001

Intermediate subunit of the Gal/GalNAc lectin of Entamoeba histolytica is a member of a gene family containing multiple CXXC sequence motifs.

Killing by Entamoeba histolytica requires parasite adherence to host galactose- and N-acetyl-D-galactosamine (Gal/GalNAc)-containing cell surface receptors. A 260-kDa heterodimeric E. histolytica Gal/GalNAc lectin composed of heavy (Hgl) and light (Lgl) subunits has been previously described. Here we present the cloning and characterization of Igl, a 150-kDa intermediate subunit of the Gal/GalNAc lectin. Igl, Hgl, and Lgl colocalized on the surface membrane of trophozoites. Two unlinked copies of genes encoding Igl shared 81% amino acid sequence identity (GenBank accession no. AF337950 and AF337951). They encoded cysteine-rich proteins with amino- and carboxy-terminal hydrophobic signal sequences characteristic of glycosylphosphatidylinositol (GPI)-anchored membrane proteins. The igl genes lacked carbohydrate recognition domains but were members of a large family of amebic genes containing CXXC and CXC motifs. These data indicate that Igl is part of the parasite's multimolecular Gal/GalNAc adhesin required for host interaction.

Amino Acid Motifs↗

PubMed2001

New double-tracer digital radiography for analysis of spatial and temporal myocardial flow heterogeneity.

A new high-resolution digital radiographic technique based on the deposition of (125)I- and (3)H-labeled desmethylimipramine (IDMI and HDMI, respectively) was developed for the assessment of spatial and temporal myocardial flow heterogeneity at a microvascular level. The density distributions of two tracers, or relative flow distributions, were determined by subtraction digital radiography using two imaging plates of different sensitivity. The regions resolved are comparable in size to vascular regulatory units (400 x 400 microm(2)). This method was applied to the measurement of within-layer myocardial flow distributions in Langendorff-perfused rabbit hearts. The validity of this method was confirmed by the strong correlation between regional densities of two tracers injected simultaneously (r = 0.89 +/- 0.03, n = 8). The temporal flow stability was evaluated by a 90-s continuous IDMI injection and subsequent bolus HDMI injection (n = 8). Regional densities of the two tracers were fairly correlated (r = 0.86 +/- 0.03), indicating that the spatial pattern of flow distribution was stable even at a microvascular level over a 90-s period. The effect of microsphere embolization on the flow distribution was also investigated by the sequential injections of IDMI, 15-microm microspheres, and HDMI at 20-s intervals (n = 8). Microembolization increased the coefficient of variation of tracer density from 19 to 25% (P < 0.05), whereas the regional densities of two tracers were still correlated substantially, as in the case of no embolization (r = 0.84 +/- 0.06). Thus the microsphere embolization enhanced flow heterogeneity with increasing flow differences between control high-flow and control low-flow regions but rather maintained the pattern of flow distribution. In conclusion, double-tracer digital radiography will be a promising method for the spatial and temporal myocardial flow analysis at microvascular levels.

Animals↗

PubMed2001

Stenosis differentially affects subendocardial and subepicardial arterioles in vivo.

The presence of a coronary stenosis results primarily in subendocardial ischemia. Apart from the decrease in coronary perfusion pressure, a stenosis also decreases coronary flow pulsations. Applying a coronary perfusion system, we compared the autoregulatory response of subendocardial (n = 10) and subepicardial (n = 12) arterioles (<120 microm) after stepwise decreases in coronary arterial pressure from 100 to 70, 50, and 30 mmHg in vivo in dogs (n = 9). Pressure steps were performed with and without stenosis on the perfusion line. Maximal arteriolar diameter during the cardiac cycle was determined and normalized to its value at 100 mmHg. The initial decrease in diameter during reductions in pressure was significantly larger at the subendocardium. Diameters of subendocardial and subepicardial arterioles were similar 10--15 s after the decrease in pressure without stenosis. However, stenosis decreased the dilatory response of the subendocardial arterioles significantly. This decreased dilatory response was also evidenced by a lower coronary inflow at similar average pressure in the presence of a stenosis. Inhibition of nitric oxide production with N(G)-monomethyl-L-arginine abrogated the effect of the stenosis on flow. We conclude that the decrease in pressure caused by a stenosis in vivo results in a larger decrease in diameter of the subendocardial arterioles than in the subepicardial arterioles, and furthermore stenosis selectively decreases the dilatory response of subendocardial arterioles. These two findings expand our understanding of subendocardial vulnerability to ischemia.

Animals↗

PubMed2001

The role of ANG II and endothelin-1 in exercise-induced diastolic dysfunction in heart failure.

The diastolic dysfunction present at rest in congestive heart failure (CHF) is exacerbated during exercise (Ex). Increases in circulating ANG II and endothelin-1 (ET-1) during Ex may contribute to this response. We assessed the effect of Ex on circulating plasma levels of ANG II and ET-1 and left ventricular (LV) dynamics before and after pacing-induced CHF at rest and during Ex in nine conscious, instrumented dogs. Before CHF, there were modest increases in circulating levels of ANG II (but not ET-1) during Ex. LV diastolic performance was enhanced during Ex with decreases in the time constant of LV relaxation (tau), LV end-systolic volume (V(ES)), and LV minimum pressure with a downward shift of the LV early diastolic portion of the pressure-volume (P-V) loop. This produced an increase in peak LV filling rate without an increase in mean left atrial (LA) pressure. After CHF, the resting values of ANG II and ET-1 were elevated and increased to very high levels during Ex. After CHF, mean LA pressure, tau, and LV minimum pressure were elevated at rest and increased further during Ex. Treatment with L-754,142, a potent ET-1 antagonist, or losartan, an ANG II AT(1)-receptor blocker, decreased these abnormal Ex responses in CHF more effectively than an equally vasodilatory dose of sodium nitroprusside. Combined treatment with both ANG II- and ET-1-receptor blockers was more effective than either agent alone. We conclude that in CHF, circulating ANG II and ET-1 increase to very high levels during Ex and exacerbate the diastolic dysfunction present at rest.

Acetamides↗

PubMed2001

Effect of dietary conjugated linoleic acid on the in vivo growth of rat hepatoma dRLh-84.

We examined the effect of dietary conjugated linoleic acid (CLA) on the growth of injected hepatoma dRLh-84 in Donryu rats. After experimental diets containing 0% or 2% CLA were given to male Donryu rats for 3 wk, dRLh-84 cells were injected into the left lobe of the hepatic capsule, and the experimental diet was continued. The cells formed a solid tumor > or = 1 wk after the injection, and thereafter the tumor grew with feeding duration. In a morphological study, this tumor appeared to be a low-differentiated hepatoma, and there was no remarkable difference in the morphology of the tumor between 0% and 2% CLA groups. Tumor weight was significantly higher in the 2% CLA group than in the 0% CLA group throughout the feeding period after the injection. Serum glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase activities were significantly higher in 2% CLA-injected rats than in 0% CLA-injected rats at 3 wk after the injection. CLA upregulated acyl-CoA oxidase activity, especially 1 wk after the injection. However, dietary CLA did not activate carnitine palmitoyl transferase II, which is a rate-limiting enzyme in the mitochondrial beta-oxidation pathway. Natural killer cell activity in the spleen tended to be higher in injected rats, but a significant effect of dietary CLA was not recognized. Serum interferon-gamma and tumor necrosis factor-alpha levels were higher in injected than in sham rats. Moreover, these levels were higher in 2% CLA groups than in the respective 0% CLA groups.

Adipose Tissue↗

PubMed2001

Transient but marked ST elevation in precordial leads caused by ischemia of the isolated right ventricular branch.

The present case is a 64 year-old man in whom transient but marked ST elevation was confirmed in the contralateral precordial leads (V1-3) during percutaneous transluminal coronary angioplasty (PTCA) of the proximal right coronary artery, suggesting that the patient had anteroseptal ischemia. The ST elevation persisted even after the balloon was deflated, and no changes in the left coronary artery were detected. In addition, blood flow in the affected area of the right coronary artery was favorable and there was a transient delay only in the right ventricular branch. Once blood flow in the right ventricular branch improved, ST returned to baseline, and when the right ventricular branch was again occluded by the balloon, ST elevation occurred in a reproducible manner. Hence, the electrocardiographic changes in the precordial leads were caused by occlusion of the right ventricular branch. It is rare to observe ST elevation caused by isolated right ventricular branch ischemia.

Angioplasty, Balloon, Coronary↗

PubMed2001

Development of assay system for immunoglobulin production regulatory factors using whole cell cultures of mouse splenocytes.

We tried to establish an assay system for screening and assessment of immunoregulatory factors using whole cell cultures of mouse splenocytes and found that splenic adhesive cells markedly increased immunogobulin (Ig) production of splenocytes. In the absence of adhesive cells, lipopolysaccharides, pokeweed mitogen, and phytohemagglutinin stimulated the production of IgA, IgG, and IgM in a class-dependent manner. Adhesive cells increased more markedly Ig production of splenocytes stimulated with these mitogens. When mouse splenocytes were cultured with milk proteins in the absence of adhesive cells, lactoferrin, beta-lactoglobulin, alpha-casein, and beta-casein stimulated IgA and IgG production. Adhesive cells increased IgA production of splenocytes stimulated with milk proteins, especially. These results suggest that the assay system is useful for assessment of Ig production-regulating factors.

Animals↗

PubMed2001

Oxidative stress by visible light irradiation suppresses immunoglobulin production in mouse spleen lymphocytes.

In this study, we attempted to induce the oxidative stress in mouse spleen lymphocytes with visible light irradiation and examined the effects of lipid peroxidation on immunoglobulin (Ig) production. The spleen lymphocytes were isolated from 8-week-old male balb/c mice and irradiated with 300 W visible light. When the cells were cultured for 72 hr, Ig contents in culture supernatants were decreased gradually by irradiation for over 30 min. The cell viability was also lowered by the irradiation. Intracellular phosphatidylcholine hydroperoxide (PCOOH) levels and thiobarbituric acid-reactive substances (TBARS) values in culture supernatants were measured as indices of lipid peroxidation and we found that Ig production by mouse spleen lymphocytes was suppressed accompanied with the progress of peroxidation of intracellular phospholipids. Cell membrane fluidity was also significantly decreased, but the intracellular Ig level was not changed in the irradiated cells. These results suggest that the peroxidation of intracellular lipids is a cause of the suppression of Ig production by mouse spleen lymphocytes via lowering cell viability and suppressing Ig synthesis and secretion.

Animals↗

PubMed2001

Efficacy of transthoracic needle aspiration in community-acquired pneumonia.

OBJECTIVE: To evaluate the indications, efficacy, and safety of transthoracic needle aspiration (TNA) in diagnosing community-acquired pneumonia (CAP). METHODS: TNA procedure was performed using an ultrathin needle with ultrasonography and/or computed tomography. The aspirate samples were Gram-stained and sent for cultures. The results were compared with those from conventional microbiological studies. PATIENTS: Sixty patients with CAP who were admitted to the hospital and were studied prospectively between July 1994 and June 1999 were included in the study. RESULTS: TNA culture was positive in 30 cases (50.0%). Streptococcus pneumoniae was the most frequently isolated pathogen, followed by the Streptococcus milleri group, and anaerobes. The results of TNA were consistent with those of quantitative sputum cultures in 9 patients and with those of blood cultures in 4. Complications arose in 3 patients who developed small to moderate pneumothorax. CONCLUSIONS: TNA is a safe procedure with a good diagnostic yield. In particular, anaerobes or microaerophils such as the S. milleri group were highly detectable by TNA. The results obtained by TNA were highly consistent with those obtained by the gold standard methods. Combined with conventional methods, TNA is considered highly useful for determining the etiology of CAP.

Adult↗

PubMed2001

[Memory function in patients with Parkinson's disease: in relation to neuropsychological tests and cerebral blood flow].

We conducted a neuropsychological comparison between Parkinson's disease (PD; n = 24) and healthy control subjects (n = 12) using Rey's auditory-verbal learning test (RAVLT) and the Rey-Osterrieth complex figure test (RCFT) assessing memory function. In addition, to determine the function of cortical and subcortical areas, we measured the regional cerebral blood flow (rCBF) using N-isopropyl-p[123I]-iodoamhetamine (123I-IMP) and single photon emission computed tomography (SPECT) and analyzed the relationships between brain regions and memory function. On the RAVLT, significant group differences in recall words were found on all learning trials between patients with PD and control subjects, whereas recognition, learning rate and forgetting rate were basically the same. In addition, the primacy/recency effect was statistically equal for both groups. Results suggest faulty retrieval mechanisms in PD, whereas encoding and retention procesess did not prove to be affected. There were significant correlations between perfusion of the prefrontal and parietal cortices and total number of free recall in five trials. On the RCFT, recalls after 30 sec and 30 min were impaired in patients with PD although no significant difference in accuracy scores obtained in copy was noted. A percent recall score calculated using the formula 100 x [1 - (copy-recall)/copy] was also decreased in patients with PD. There were significant correlations between perfusion of the occipital and parietal cortices and percent recall score. Our data suggest that auditory memory deficits based on the RAVLT in PD may be mainly related to frontal and parietal cortical dysfunction, while visual recall deficits based on the RCFT may be related to the parieto-occipital cortical dysfunction.

Aged↗