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Biomedical subjects

T Yoshihara

Publications and source records attributed to T Yoshihara.

At least 73 records · Page 4Linked to original sources
PubMed1999

Ultrastructural localization of glucose transporter 1 (GLUT1) in guinea pig stria vascularis and vestibular dark cell areas: an immunogold study.

Glucose transporter 1 (GLUT1) is one of the facilitated-diffusion glucose transporters, which plays a major role in the glucose transport across blood-tissue barriers. We demonstrated localization of GLUT1 in guinea pig stria vascularis (SV) and vestibular dark cell areas, using electron microscopy. GLUT1 immunoreactivity was seen mainly in the SV. Electron microscopically, immunogold particles were localized along the plasma membranes of the basal cells and the basolateral infoldings of the marginal cells. Erythrocyte membranes and the capillary walls in both the SV and the dark cell areas were also positive for GLUT1. These results indicate that GLUT1 is involved in glucose regulation for energy metabolism in the marginal cells and vestibular dark cells, and in glucose transport between blood and perilymph.

Animals↗
PubMed1999

A survey of white line disease in Japanese racehorses.

A survey was carried out into white line disease in 1781 Thoroughbred racehorses kept in stables at the Japan Racing Association (JRA) Miho Training Center (MTC) September-October 1996. The survey was conducted while horses were being shod by farriers. The horses that still exhibited damaged white lines after regular trimming were diagnosed as having white line disease. The factors recorded were age, sex, number of diseased horses, number of diseased hooves, number of lesions by region over the bearing border of the hoof and the classified length of such lesions. The percentage of total diseased horses was 11.5% (204 animals), with incidence increasing significantly with age (P< or =0.01). Occurrence was independent of sex (P>0.05) was more frequent in the fore- than in the hindhoof and developed more frequently at the toe than at any other region of the forehoof-bearing border. Most lesions ranged from 20 to 30 mm in length.

Animals↗
PubMed1999

Two distinct interleukin-3-mediated signal pathways, Ras-NFIL3 (E4BP4) and Bcl-xL, regulate the survival of murine pro-B lymphocytes.

Hematopoietic cells require cytokine-initiated signals for survival as well as proliferation. The pathways that transduce these signals, ensuring timely regulation of cell fate genes, remain largely undefined. The NFIL3 (E4BP4) transcription factor, Bcl-xL, and constitutively active mutants of components in Ras signal transduction pathways have been identified as key regulation proteins affecting murine interleukin-3 (IL-3)-dependent cell survival. Here we show that expression of NFIL3 is regulated by oncogenic Ras mutants through both the Raf-mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways. NFIL3 inhibits apoptosis without affecting Bcl-xL expression. By contrast, Bcl-xL levels are regulated through the membrane proximal portion in the cytoplasmic domain of the receptor (betac chain), which is shared by IL-3 and granulocyte-macrophage colony-stimulating factor. Activation of either pathway alone is insufficient to ensure cell survival, indicating that multiple independent signal transduction pathways mediate the survival of developing B-lymphoid cells.

Animals↗
PubMed1999

Comparative study between chemiluminescence assay and two different sensitive polymerase chain reactions on the diagnosis of serial herpes simplex virus encephalitis.

OBJECTIVE: A prospective study was undertaken on the diagnosis of herpes simplex encephalitis (HSVE) by comparing chemiluminescence assay (CL) and two different sensitive polymerase chain reactions (PCRs). METHODS: The materials comprised 53 serial CSF samples from 31 patients with acute encephalitis with suspected HSVE. Each CSF was distributed to three independent laboratories to perform quantitative measurements by CL, the low sensitive (single) PCR, and high sensitive (nested) PCR. The CL provided a method of detecting HSV itself and the small fragment with HSV antigenicity which was composed of viral component proteins. The serial CSFs were found retrospectively to comprise 24 samples from 11 patients with HSVE due to HSV1 and 29 samples from 20 patients with non-HSVE. RESULTS: the CL showed 50 to 48 000 pfu/ml in all samples of HSVE (except one) taken from the 3rd to the 25th day. The low sensitive PCR demonstrated 50 to 47 000 pfu/ml in only six samples of HSVE. The high sensitive PCR disclosed less than 100 to 120 000 copies/ml in 11 samples of HSVE. At the acute stage from the 1st to 7th day, the sensitivities of CL and the high sensitive PCR were 100%, but that of the low sensitive PCR was 75%. The sensitivity of CL was significantly higher than those of both PCRs after the acute stage on the 15th to 32nd day. The specificities and positive predictive values of the three methods were 100%. However, the negative predictive value of CL was significantly higher than that of the low sensitive PCR. CONCLUSIONS: The sensitivity of CL is equivalent to that of the high sensitive PCR during the acute stage and significantly higher than that of the high sensitive PCR after the acute stage. A clear difference in sensitivity exists between the different PCRs. A combination of the PCR, chemiluminescence assay, and serological antibody diagnosis is currently considered the most effective approach for the clinical diagnosis of HSVE.

Adult↗
PubMed1999

Measurement for breath concentration of hydrogen and methane in horses.

This study concerns the establishment of a simple testing method for breath concentration of hydrogen and methane in horses. Twenty-eight healthy thoroughbreds and 24 Arabians were used. Breath samples were collected using one-minute closed circulatory respiration through an aluminum bag filled with 10 liters of pure oxygen, which was mounted on the subjects by means of a face mask. Breath samples obtained, were analyzed by gas chromatography. A significant correlation in both hydrogen and methane levels was observed for samples collected at separate times. These findings confirmed the usefulness of our approach for testing breath concentrations of hydrogen and methane in horses.

Abdomen, Acute↗
PubMed1999

The effect of motilin on the regulation mechanism of intestinal motility in conscious horses.

Laparotomy was performed on seven thoroughbreds to attach a force transducer to the proximal jejunum, distal jejunum, and ileum, as well as to the serous membrane of the cecum. Following observation of intestinal motility in conscious horses, they were intravenously injected with motilin (0.6 microgram/kg) to examine its effect on intestinal motility. Strong contractions peculiar to horses were observed in small intestine. Further, motilin caused strong contractions in the proximal jejunum. The results suggested the involvement of motilin in the regulation mechanism of intestinal motility.

Animals↗
PubMed1999

Pathologic and electrocardiographic findings in sudden cardiac death in racehorses.

Five racehorses in apparently normal condition succumbed to sudden cardiac death (SCD) during or shortly after intensive training exercise. Cardiopathologic examination was performed. In 1 of the 5 horses, the use of an electrocardiogram (ECG) recording taken continuously for 440 sec enabled us to analyze some of the arrhythmias in the terminal event of SCD. The ECG tracing exhibited the R-on-T phenomenon following a pair of ventricular premature contractions (VPCs). The phenomenon rapidly degenerated into ventricular fibrillation, which led to cardiac arrest. In all 5 horses cardiopathologic examination revealed the following lesions: (i) foci of myocardial fibrosis in the right atrium located close to the sinoatrial (SA) node, (ii) fibrotic and/or fibroplastic changes in the upper portion of the interventricular septum, including the atrioventricular (AV) conduction system, and (iii) arterio- and arteriolosclerosis of the SA and AV node vessels. Pathogenetically, the process by which the focal lesions of myocardial ischemia secondary to vascular sclerosis progressed into fibrosis and/or fibroplasia could play a major role in the genesis of arrhythmias. Presumably the fibrotic and/or fibroplastic changes in the area of the AV bundle and its bundle branches are closely related to the onset of fatal ventricular arrhythmias such as VPCs, deteriorating into ventricular fibrillation. SCD in training and racing Thoroughbred horses appears to be due to arrhythmia.

Animals↗
PubMed1999

Purification and biochemical characterization of pulmonary surfactant protein A of horses.

OBJECTIVE: To characterize surfactant protein isolated from bronchoalveolar lavage fluids of healthy horses. ANIMALS: 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) that did not have a history or clinical signs of respiratory tract disease. PROCEDURE: Bronchoalveolar lavage fluid (BALF) was obtained and centrifuged at 33,000 X g. Lipid was removed from precipitated fractions by means of extraction with 1-butanol, and organic solvent-insoluble protein precipitates were dialyzed against Tris buffer. The suspension was centrifuged, and supernatant was placed in a mannose-Sepharose affinity column, with calcium. The bound protein fraction was analyzed by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western immunoblot analysis, and amino acid sequencing. A liposome-aggregation assay was also performed, using purified proteins. RESULTS: Protein isolated by use of mannose-affinity matrices was identified as surfactant protein A (SP-A). It had carbohydrate-binding and phospholipid-aggregation properties characteristic of SP-A isolated from other animal species. The partial primary sequence of the isolated protein had high homology with rat and human SP-A. Furthermore, the equine SP-A reacted with anti-human and anti-rat SP-A specific antibodies. CONCLUSION: Analysis of these findings indicated the existence of SP-A in pulmonary tissues of horses. CLINICAL RELEVANCE: Measurement of SP-A concentrations may be useful for clinicians evaluating pulmonary disease of horses.

Amidohydrolases↗
PubMed1999

Purification and biochemical characterization of equine pulmonary surfactant protein D.

OBJECTIVE: To characterize surfactant protein D (SP-D) isolated from bronchoalveolar lavage fluid (BALF) of healthy horses. SAMPLE POPULATION: BALF from 10 Thoroughbreds (5 males, 5 females; 26 to 40 months old) without history or clinical signs of respiratory tract disease. PROCEDURE: BALF was obtained and centrifuged at 33,000 X g. The supernatant was applied to a mannose-Sepharose 6B affinity column in the presence of calcium, and the bound protein fraction was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis; amino acid composition was determined and partial sequencing was done. Phospholipid binding and liposome aggregation assay were performed, using purified proteins. RESULTS: The protein isolated by use of mannose affinity matrices was SP-D. It bound carbohydrates and phosphatidylinositol, which are the characteristic features of SP-D isolated from other animal species. Amino acid analysis and partial primary sequence of the isolated protein indicated high homology with rat and human SP-D. Furthermore, immunoblot analysis indicated that equine SP-D reacted with human and rat SP-D-specific antibodies. CONCLUSION AND CLINICAL RELEVANCE: SP-D exists in equine lungs; its measurement may be useful in evaluating equine lung disease.

Amino Acids↗
PubMed1999

[Clinical outcome of an anticancer agent screening test with primary culture cells].

Cancer cells are tested for sensitivity to anticancer agents before the drugs are used for treatment in clinical settings, but the results of these tests have not always been reported fully. Since 1973, one of the authors (Hirono) has been performing sensitivity tests of anticancer drugs by using primary culture cells derived from human cancer tissue, taking into account in vivo status and taking great care to reduce the number of procedural errors. From 1991, flow cytometry has also been adopted for use in anticancer drug sensitivity tests. In the present study, the outcomes of cancer patients were compared by dividing them into a group treated only with anticancer agents to which cancer cells had responded in sensitivity tests, and a group treated with other drugs. The subjects consisted of 132 patients with endometrial cancer stage III (n = 26) and IV (n = 10), ovarian cancer stage III (n = 26) and IV (n = 7), peritonitis carcinomatosa (n = 18), and suspected advanced ovarian cancer (n = 45). There was a significant prolongation in median survival time and survival time among the non-survivors according to the results of a Kaplan-Meier analysis. These findings suggest that sensitivity testing of cancer cells to anticancer drugs should be performed before the start of cancer chemotherapy in the clinical setting.

Adult↗
PubMed1998

Intrahippocampal D-cycloserine improves MK-801-induced memory deficits: radial-arm maze performance in rats.

In order to investigate whether strychnine-insensitive glycine sites coupled with hippocampal NMDA (N-methyl-d-aspartate) receptors are involved in spatial memory in rats, we examined the effects of intrahippocampal treatment of d-cycloserine (DCS), a glycine-site agonist, on spatial-memory deficits which were produced by an NMDA antagonist MK-801 (dizocilpine) on the radial-arm maze task. After the acquisition of this task, the radial-maze performance was tested under the combined treatments of intraperitoneal MK-801 or saline (SAL) and intrahippocampal DCS or SAL. The results showed that MK-801 impaired the performance, and that DCS improved the MK-801-induced performance impairment. These results suggest that glycine sites are involved in spatial memory through their modulatory action on hippocampal NMDA receptors.

Analysis of Variance↗
PubMed1998

Effect of passive immunization against inhibin on FSH secretion, folliculogenesis and ovulation rate during the follicular phase of the estrous cycle in mares.

Physiological roles of inhibin in mares were investigated by means of passive immunization using an antiserum to inhibin that had been raised in a castrated goat. Eight mares were given an intravenous injection of either 100 mL (n = 4) or 200 mL (n = 4) of inhibin antiserum 4 d after a single intramuscular injection of PGF2 alpha on Day 8 after ovulation, 4 control mares were treated with 100 mL castrated goat serum in the same manner. Jugular vein blood samples were collected after treatment with the serum until 192 h post treatment. Follicular growth and ovulations were monitored by ultrasound examination at 24-h intervals. The ability of the inhibin antiserum to neutralize the bioactivity of equine inhibin was examined in vitro using a rat pituitary cell culture system. Suppression of secretion of FSH from cultured rat pituitary cells by equine follicular fluid was reversed by the addition of increasing doses of the inhibin antiserum, thereby indicating its bioactivity. Plasma levels of FSH and estradiol-17 beta were higher in mares treated with the inhibin antiserum. The ovulation rate was significantly higher in mares treated with antiserum (100 mL = 3.75 +/- 0.63; 200 mL = 4.50 +/- 0.65) than in control mares (1.25 +/- 0.25). These results demonstrate that inhibin is important in regulating FSH secretion and folliculogenesis in mares. They also show that neutralization of the bioactivity of inhibin may become a new method for the control of folliculogenesis and ovulation rate in mares.

Animals↗
PubMed1998

Tamsulosin: assessment of affinity of 3H-prazosin bindings to two alpha1-adrenoceptor subtypes (alpha1H and alpha1L) in bovine prostate and rat heart and brain.

1. The present study was designed to assess the displacement potencies of tamsulosin to 3H-prazosin bindings in two alpha1-adrenoceptor (AR) subtypes (alpha1H and alpha1L) in bovine prostate, rat heart and brain compared with those of amosulalol, labetalol, ketanserin, clonidine and propranolol. 2. The pKi values of tamsulosin to alpha1H and alpha1L subtypes in bovine prostate were 9.13 and 8.99 and these values were almost the same as those of prazosin. On the other hand, low pKi binding values of amosulalol, labetalol, ketanserin, clonidine and propranolol to these subtypes were observed. 3. Low pKi values of tamsulosin to alpha2- and beta-ARs and muscarinic and 5HT2 receptors in the rat brain were observed. 4. These results suggest that tamsulosin has high affinities to alpha1L-AR subtypes in bovine prostate and rat hearts as well as alpha1H-AR subtypes, implying an inhibitory effect of this drug on the contraction of the prostate.

Adrenergic alpha-Antagonists↗
PubMed1998

Onychomycosis in white line disease in horses: pathology, mycology and clinical features.

This paper describes onychomycosis in horses and reports the pathological findings, associated fungi and incidence of concurrent white line disease. In addition to these observations, relevance between post mortem and clinical findings of onychomycosis are discussed in 3 necropsied horses. Samples were collected from 100 hooves from a total of 51 Thoroughbreds suffering from white line disease. Of these, 15 hooves from 13 horses were also complicated with severe hoof wall fissure formation. Preparations from the same samples were used both for histopathology and for culture to identify the associated fungi. Onychomycosis was diagnosed when it could be confirmed histologically. Fungal identification was based on morphological characteristics in culture and the associated fungi were determined by comparison with culture morphology. As a result, 10 samples collected from horses were diagnosed as suffering from onychomycosis. Seven of these showed complicating severe inner hoof wall fissures and the soil fungus Scedosporium apiospermum or the teleomorph of this fungus, i.e., Pseudallescheria boydii, was isolated. The fungus was found to be ubiquitous in the fissure cavities, the terminal horn of the white line and the terminal horn-like laminae of the metaplastic white line-like tissue. It can be concluded that onychomycosis frequently causes white line disease and/or makes it worse. Associated with deterioration of the submural condition, the main associated fungus for onychomycosis in this series, was Genus Scedosporium and the most susceptible region was the terminal horn of the hypertrophied white line and/or the terminal horn-like laminae of the metaplastic white line-like tissue.

Animals↗
PubMed1998

The application of electrocecography for evaluation of cecum motility in horses.

Electrogastrography (EGG), in which the electrical activity of the smooth muscular layer of the stomach is recorded percutaneously through the abdominal wall, has been applied in recent years to humans as a non-invasive method. In acute abdominal disease in horses, it is considered diagnostically useful to analyze digestive activity using EGG. Electrocecography (ECG) was examined to determine its effectiveness in evaluating equine digestive motility through comparison, after xylazine administration, between the results of the percutaneous ECG method and the results obtained using a strain-gauge force transducer (Force Transducer) chronically attached to the serous membrane of the cecum. As subjects, the test used six male thoroughbreds (average weight: 457.5 +/- 9.2 kg). The test showed a reduction in both the percutaneous electrical potential of the cecum in ECG and in cecal contractions measured with the Force Transducer. After xylazine administration, an average rates of decrease of the amplitude from the control period were 17.8 +/- 3.4% and 20.0 +/- 4.6% respectively, demonstrating a significant correlation (r = 0.90) between the two methods. On the other hand, power distribution centered around 6 cycles per minute in a Fourier transform (FFT) analysis of ECG, thought similar to the contraction frequency of 5.4 +/- 3.0 per minute observed with the Force Transducer. After xylazine administration, the total frequency band (1.8-12 cycle per min) in the running spectrum total power in ECG decreased to 37.0 +/- 5.1% of the pre-xylazine value. Based on these findings, it appears that the ECG potential reflected electrical activity of cecal origin, suggesting high clinical applicability of ECG to the percutaneous evaluation of equine cecal motility.

Adrenergic alpha-Agonists↗
PubMed1998

Characteristics of respiratory function during swimming exercise in thoroughbreds.

Equine respiratory patterns during swimming were examined in five normal horses. The experiment included a preliminary warming-up stage and 6 circuits of swimming around an annular pool of a 50-meter-circumference. The horses were examined for respiratory rates, intratracheal pressures, inspiratory time (TI), expiratory time (TE), respiratory cycle (T; TI + TE), heart rates, blood lactate concentrations, hematocrit and blood gases. The respiratory rates were maintained around 25/min. Blood gas values changed significantly during swimming. The intratracheal pressures during expiration and inspiration increased significantly with exercise duration compared to the immediately after the warming-up stage. The duty ratio (TI/T) averaged 0.33, which implied that the expiratory time was roughly doubled the inspiratory time. We considered that a longer expiratory time may limit sudden collapse of airways by water pressure during swimming and prevent a radical decrease of air space volume, thus maintains buoyancy.

Animals↗
PubMed1997

Infantile schwannoma of the maxillary sinus.

A rare case of a 5-year-old female with schwannoma of the maxillary sinus is presented. She had complained of painless swelling of the left cheek and hard palate for a duration of one year. Preoperatively, a CT scan strongly suggested it to be a maxillary cyst with an erupted tooth rather than neoplasm. The tumour was completely removed after embolization of the left internal maxillary artery. The tumour was composed of spindle cells in a palisading pattern and intercellular collagenous fibres. Mitotic figures and atypical nuclei were not observed. Immunohistochemically, the majority of the cells were positive for NSE and S-100 protein, whereas GFA and PCNA showed little immunoreaction. The pathological diagnosis was Antony type A of schwannoma arising in the maxillary sinus.

Child, Preschool↗