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Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 163 records · Page 9Linked to original sources
PubMed2000

Secretion of hen egg white lysozyme from Kluyveromyces lactis.

Hen egg white (HEW) lysozyme was correctly processed and efficiently secreted from an alternative yeast, Kluyveromyces lactis. We constructed secretion vectors using PHO5, PGK, and LAC4 promoters, and found that the highest secretion was obtained under the direction of the PGK promoter in non-selective rich medium. K. lactis secreted HEW lysozyme with two-fold higher efficiency than S. cerevisiae, estimated by using a K. lactis-S. cerevisiae shuttle vector.

Animals↗
PubMed2000

Ovarian and retroperitoneal teratomas in a dog.

A 2-year-old female Labrador retriever was presented with anorexia and abdominal distention. Laparotomy revealed the presence of a 31-cm ovoid mass in the portion of the left ovary and an 11-cm round mass in the left retroperitoneal region. Both masses were surgically removed. Histopathological examination of the masses revealed a mixture of tissues characteristic of teratomas, such as multiple bronchial and intestinal cysts, hair follicles, sebaceous and apocrine sweat glands, and neuron tissue with intervening cartilage, bone and fat tissue. This paper appears to be the first report of primary retroperitoneal teratoma in the dog.

Animals↗
PubMed2000

Protective effects of (-)-epigallocatechin gallate and (+)-catechin on paraquat-induced genotoxicity in cultured cells.

The protective effects of green tea polyphenols on paraquat-induced genotoxicity in cultured cells were studied. (-)-Epigallocatechin gallate (EGCG), the major constituent of green tea, and (+)-catechin (CT), a minor constituent, equivalently decreased the frequencies of sister-chromatid exchanges (SCE) induced by paraquat (PQ), which is a generator of reactive oxygen species. These polyphenols were effective at concentrations of 1.0 microM and above. A reduction of the effect on the cell cycle rate caused by PQ was found when EGCG and CT were added at concentrations of more than 10.0 microM. These concentrations of EGCG and CT alone had no effect on cell cycle rate, which is used as index of cell proliferation. Decreases in the cell cycle rate were found at 200 microM EGCG and CT in the 24 hr exposure period. The equivalent effectiveness of EGCG and CT suggested the possibility of other mechanisms, apart from acting as reactive oxygen species scavengers, because it has been reported that EGCG is the most potent scavenger among tea catechins. From the present study, it was suggested that green tea and foods containing these polyphenols may be beneficial to human health by protecting against reactive oxygen species-induced genotoxicity.

Animals↗
PubMed2000

Comparison of sperm motility test methods (except computer-assisted sperm analysis) in rats under the condition of alfa-chlorohydrin treatment--collaborative investigation.

A comparison among rat sperm motility test methods including percent of motile sperm (% Motile), scoring method (Scoring), Ishii's method, Progressive Motility Test (PMT) and Sperm Quality Analyzer (SQA), was conducted using data gathered from eleven laboratories. As a unified study design, mature male rats were orally treated daily for approximately 1 week with alpha-chlorohydrin (ACH), which is known to affect the sperm motility at the epididymis, at dose levels of 2.5, 5 and 10 mg/kg, and then subjected to more than two test methods for sperm motility in each laboratory. Scoring (4 or 5 grades), Ishii's method, PMT and SQA showed high sensitivity for the detection of the effects of ACH, which were not considered to be inferior to a computer-assisted sperm analyzer (CASA). Longer incubation time before testing was considered to contribute to detecting the effects of ACH. In particular, we realized that Scoring was a favorable method even if the demerit of poor objectivity was allowed for. Percent Motile showed lower sensitivity than other test methods. The differences in sensitivity between % Motile and other methods were considered to be based on whether the defects of progressive motion could be detected. Although % Motile cannot clearly judge whether immotile sperm are dead or alive, the value is a great help for the interpretation of the result from other methods. Based on the characters for detectability, objectivity and efficiency, the most suitable method of sperm motility should be selected according to the purpose of the toxicity study.

Animals↗
PubMed2000

Radiation-induced diffuse brain injury in the neonatal rat model--radiation-induced apoptosis of oligodendrocytes.

The mechanism of radiation-induced diffuse brain injury was investigated using a model of delayed myelination in the irradiated neonatal rat brain in which the number of oligodendrocytes decreases without associated necrosis of the cerebral white matter. Immunohistochemical analysis using antibody against the large myelin-associated glycoprotein, a specific marker of oligodendrocytes at an early stage of development, showed that the number of the oligodendrocytes associated with myelination decreased in the irradiated hemisphere 1 day after irradiation and remained low until 5 days after irradiation. In situ terminal deoxynucleotidyl transferase-mediated nick end-labeling assay revealed that apoptosis mainly occurred in the cerebral white matter of the irradiated hemisphere. Three hours after irradiation, apoptotic cells were found in the subcortical white matter and the periventricular white matter. Six hours after irradiation, apoptotic cells were found in the internal capsule, and the numbers of apoptotic cells in the periventricular white matter and subcortical white matter increased. One day after irradiation, the number of apoptotic cells in the periventricular white matter decreased. Three days after irradiation, apoptotic cells were not observed in the cerebral white matter. These results suggest that the oligodendrocytes associated with myelination may be damaged via radiation-induced apoptosis, and depletion of the oligodendrocytes may cause delay of myelination.

Animals↗
PubMed2000

Platelet aggregation in dogs with mitral valve regurgitation.

OBJECTIVE: To compare platelet aggregation in healthy dogs and dogs with mitral valve regurgitation (MVR) to determine whether regurgitation had an effect on platelet function. ANIMALS: 32 dogs with MVR and 43 healthy dogs. PROCEDURE: Platelet aggregation was measured with an aggregometer, using adenosine 5'-diphosphate as the aggregating agent, and the maximum aggregation and the enhancement of platelet sensitivity (EPS) values were calculated. RESULTS: Platelet count and maximum aggregation were not significantly different between healthy dogs and dogs with MVR. However, EPS values in dogs with MVR were significantly higher than values in healthy dogs. Platelet count and maximum aggregation were not significantly different between dogs classified as New York Heart Association functional class I or II and dogs classified as functional class III or IV; however, EPS values were significantly higher in dogs classified as functional class III or IV. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that platelet aggregation is decreased in dogs with MVR and that the EPS value may be more sensitive to differences in disease severity than in measurement of maximum aggregation.

Adenosine Diphosphate↗
PubMed2000

[Epilepsy surgery for focal cortical dysplasia and dysembryoplastic neuroepithelial tumor].

We studied six patients with focal cortical dysplasia (CD) and four patients with dysembryoplastic neuroepithelial tumor (DNT) who had surgical resection for medically intractable epilepsy. In all CD patients, ictal single photon emission computed tomography (SPECT) using 99mTc-ECD revealed hyperperfusion in the regions where magnetic resonance (MR) imaging showed CD abnormalities. Interictal epileptiform activity and ictal seizure onset on electrocorticography using subdural strip or grid electrodes were demonstrated in the CD itself. In contrast, in all DNT patients, interictal SPECT disclosed hypoperfusion in the area of the lesions. Ictal SPECT in one DNT patient disclosed hyperperfusion in the superior area of the region where MR imaging showed cystic abnormalities. Interictal spiking in all DNT patients and ictal seizure onset in two DNT patients were demonstrated not in the lesions themselves but in the distinct zone from the region of the tumor-involved brain. All CD patients who underwent lesionectomy became seizure-free with a mean follow-up period of 33.5 months. All DNT patients who underwent lesionectomy and resection of the epileptogenic cortex became seizure-free or had their seizure significantly reduced a mean follow-up period of 41.5 months. We conclude that CDs have intrinsic epileptogenicity, while DNTs have epileptogenicity not intrinsically but in encompassed cortical surface areas.

Adolescent↗
PubMed2000

[Ineffective and recurrent cases of thoracoscopic sympathectomy for hyperhidrosis and intractable pain].

We reported the cases of thoracoscopic sympathectomy, that is, six cases of hyperhidrosis, three of post herpetic neuralgia, and four of reflex sympathetic dystrophy, including recurrent or incompletely resected or ineffective ones. Recently this procedure for hyperhidrosis had been performed frequently because of its effectiveness, less pain, early discharge and cosmetic aspect. For an ineffective case of hyperhidrosis abdominal respiration which emphasized the exhalation and using an upper abdomen decreased the sweating. The balance of autonomic nerve system, toward parasympathetic dominant, was thought to be improved by conscious respiration. The decrease of sweating right after the operation in a case of incomplete resection indicated that intraoperative maneuver could restrict the sympathetic nerve. This procedure for a pain control could be less effective than that for hyperhidrosis, so an adequate preoperative informed consent was thought to be necessary.

Adolescent↗
PubMed2000

Plasma endotoxin and serum cytokine levels in patients with alcoholic hepatitis: relation to severity of liver disturbance.

BACKGROUND: Endotoxin plays an important role in the initiation and aggravation of alcoholic liver disease. In this study, we evaluated plasma endotoxin levels and serum concentrations of cytokines and lipopolysaccharide binding protein (LBP) during the acute and recovery phase of patients with alcoholic hepatitis; we also explored the prognostic factors associated with a fatal outcome. METHODS: Fourteen patients, consisting of eight patients with alcoholic hepatitis (AH), five cirrhotics with superimposed AH (LC+AH), and one patient with severe alcoholic hepatitis (SAH), were studied. Among these, two with LC+AH died of hepatic failure. RESULTS: Plasma endotoxin levels in the acute phase were higher in patients with AH (184.4 +/- 159.4 pg/ml) and LC+AH (206.9 +/- 174.9 pg/ml) than in healthy subjects (10.4 +/- 5.5 pg/ml, p < 0.001). In particular, in one patient with SAH and one of two nonsurvivors, plasma endotoxin levels were markedly high relative to the other cases. In most survivors, plasma endotoxin levels decreased in the recovery phase, whereas they further increased at the terminal stage in one of two nonsurvivors. Serum interleukin (IL)-6 and IL-8 levels in the acute phase were significantly higher in patients with AH and LC+AH as compared with healthy subjects. These levels were especially high in nonsurvivors and in one patient with SAH. IL-10 increased in two nonsurvivors, one patient with SAH, and one with LC+AH. In the recovery phase, these cytokine levels in survivors tended to decrease, but in nonsurvivors, IL-6 remained high, and IL-8 and IL-10 further increased. Tumor necrosis factor-alpha levels were below the detection limit throughout the course in all patients. Serum lipopolysaccharide binding protein (LBP) generally was elevated in the acute phase and decreased in the recovery phase in all survivors, but in one of the nonsurvivors, LBP was elevated markedly at the terminal stage. In the acute phase, plasma endotoxin levels were correlated positively with white blood cell counts, neutrophil counts, and serum IL-8. IL-8 was correlated positively with neutrophil counts and negatively with serum cholinesterase, hepaplastin test, and serum albumin levels. IL-6 was correlated positively with white blood cell and neutrophil counts, C-reactive protein, and serum total bilirubin and negatively with hepaplastin test and serum total protein levels. Serum LBP was correlated positively with white blood cell and neutrophil counts. CONCLUSIONS: Endotoxemia and related elevation of IL-8 may play an important role in the activation and migration of neutrophils in patients with alcoholic hepatitis. Marked elevation of inflammatory cytokines, IL-6 and IL-8, are related to severity and poor prognosis of alcoholic hepatitis. Serum LBP may serve as an index of inflammatory reaction in alcoholics.

Acute-Phase Proteins↗
PubMed2000

[Clinical characteristics of seafood allergy and classification of 10 seafood allergens by cluster analysis].

The aim of this study was to investigate the clinical characteristics of children who showed sensitization to any type of seafood and to classify the 10 seafood allergens based on IgE reactivities by a cluster analysis. In children with bronchial asthma (BA) and/or atopic dermatitis (AD), we defined the 'seafood' group as 23 patients having any type of seafood specific IgE antibody (CAP system). We analyzed the clinical features, the serum total IgE and each allergen specific IgE level. In addition, ten seafood allergens were also classified by a cluster analysis. Three patients revealed immediate hypersensitivity to some seafood. The frequency of patients with AD and the total IgE in the seafood group were high and the patients in this group were tend to be sensitized to multiple allergens. Seafood allergens were classified into 4 groups, 1) salmon, sardine, horse mackerel and mackerel, 2) cod and tuna, 3) octopus and squid, and 4) crab and shrimp, by a cluster analysis. These findings corresponded to the biological classification and the classification by the reported common allergens among various types of seafood. Based on our findings, this classification is therefore considered to be useful when selecting allergens to screen for sensitization to seafood.

Allergens↗
PubMed2000

Geographic grouping of Cryptococcus neoformans var. gattii by random amplified polymorphic DNA fingerprint patterns and ITS sequence divergence.

Eleven reference strains of Cryptococcus neoformans var. gattii were analyzed by random amplified polymorphic DNA (RAPD) patterns using three oligo primers. Three major RAPD pattern profiles (profiles I, II and III) were identified with A-1 oligo primer. Each profile was found to relate to a geographic region. Since the strains which belong to profiles I and II were mainly the isolates from America, and profile III from Asia with A-1 primer, these three profiles were assigned to the geographic grouping of America-1, America-2 and Asia, respectively. Analysis of rDNA sequences coding an internal transcribed spacer (ITS) region of C. neformans var. gattii revealed that the fungus with each RAPD profile has characteristic base sequences at the four positions (10 and 15 positions in ITS1 and 8 and 56 positions at ITS2) of the ITS regions. On the basis of the combinations of the four bases specific for the ITS regions, four ITS types, AAGG (America-1), AAAC (America-2), GGGC (Asia-1) and AGGC (Asia-2) were identified: the geographic group of Asia was further classified into two subgroups of Asia-1 and Asia-2 based on the ITS typing. Clinical isolates from Thailand (6 strains) and Brazil (7 strains) were found to belong to the geographic group of America-1 nd America-2, respectively. Five reference strains of C. neoformans var. gattii from the CBS culture collection were classified into two America-2, one Asia-1 and two Asia-2 groups. This ITS region analysis allowed us to distinguish all isolates of C. neoformans var. gattii into four geographic groups based on the ITS base sequence, and further molecular epidemiological and ecological research on this fungus is recommended.

Base Sequence↗
PubMed2000

Genetics of immunoglobulin A nephropathy.

INTRODUCTION: Immunoglobulin (Ig) A nephropathy is the most common primary glomerulonephritis in the world and about 20% to 50% of patients with it develop progressive renal failure. There is considerable evidence to show that IgA nephropathy is influenced by genetic factors. The purpose of this review is to provide useful information concerning genetics of IgA nephropathy. METHODS AND RESULTS: Epidemiological, familial clustering, human leukocyte antigen and IgA immune system (immunoglobulin class switch gene, I alpha 1 germ-line transcript regulatory region gene) studies have led to the hypothesis of genetic susceptibility to IgA nephropathy. Moreover, research on renin angiotensin system, platelet activating factor acetylhydrolase, neuropeptide Y Y1 receptor and others genes has demonstrated that genetic factors influence the pathological severity and natural course of IgA nephropathy. CONCLUSIONS: The evidence presented in this review strongly supports the role of genetic factors in IgA nephropathy. Detection of genetic risk factors for IgA nephropathy will allow us to study further the pathogenesis of IgA nephropathy and devise effective therapy.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2000

Red swamp crawfish (Procambarus clarkii): an alternative experimental host in the study of white spot syndrome virus.

The pathogenicity of white spot syndrome virus (WSSV) for the red swamp crawfish (Procambarus clarkii) was investigated after infection by intramuscular (i.m.) injection and oral route. The cumulative mortality of crawfish injected i.m. with WSSV reached 100% in 5 days. After oral feeding WSSV-infected kuruma shrimp (Penaeus japonicus) muscle tissues to the crawfish the cumulative mortality of this host reached 100% in 11 days. On reinfection trials, all the crawfish fed WSSV-infected crawfish muscle tissues died in 9 days. All the shrimp injected with a filtrate of infected crawfish heart tissues died in 12 days with typical signs of white spot syndrome (WSS). Electron microscopy clearly demonstrated that WSSV propagated in the cells of the crawfish midgut. This study showed that the red swamp crawfish can be used as alternative experimental host in the study of WSSV.

Animals↗
PubMed1999

Administration of prosaposin ameliorates spatial learning disturbance and reduces cavity formation following stab wounds in rat brain.

The effectiveness of prosaposin as a neurotrophic factor was investigated using rats with bilateral stab wounds, injecting 240 ng per day of prosaposin for 3 days. In Morris water maze task, after 3 weeks postoperation, the stab-wounds rats show significant impairment in acquisition compared with the sham-operated rats. In the transfer test the mean number of crossings of the platform place in stab-wounds was significantly lower than that in sham-operated rats (P < 0.01). The stab-wounds rats treated with prosaposin showed significant improvement (P < 0.05). The cavities following stab wounds in the rats treated with prosaposin were significantly smaller than those in the rats treated with (P < 0.05). Our data support that prosaposin is likely to be a new agent for brain injury.

Animals↗
PubMed1999

Soluble interleukin-6 (IL-6) receptor with IL-6 stimulates megakaryopoiesis from human CD34(+) cells through glycoprotein (gp)130 signaling.

We have recently shown that stimulation of glycoprotein (gp) 130, the membrane-anchored signal transducing receptor component of IL-6, by a complex of human soluble interleukin-6 receptor (sIL-6R) and IL-6 (sIL-6R/IL-6), potently stimulates the ex vivo expansion as well as erythropoiesis of human stem/progenitor cells in the presence of stem cell factor (SCF). Here we show that sIL-6R dose-dependently enhanced the generation of megakaryocytes (Mks) (IIbIIIa-positive cells) from human CD34(+) cells in serum-free suspension culture supplemented with IL-6 and SCF. The sIL-6R/IL-6 complex also synergistically acted with IL-3 and thrombopoietin (TPO) on the generation of Mks from CD34(+) cells, whereas the synergy of IL-6 alone with TPO was barely detectable. Accordingly, the addition of sIL-6R to the combination of SCF + IL-6 also supported a substantial number of Mk colonies from CD34(+) cells in serum-free methylcellulose culture, whereas SCF + IL-6 in the absence of sIL-6R rarely induced Mk colonies. The addition of monoclonal antibodies against gp130 to the suspension and clonal cultures completely abrogated the megakaryopoiesis induced by sIL-6R/IL-6 in the presence of SCF, whereas an anti-TPO antibody did not, indicating that the observed megakaryopoiesis by sIL-6R/IL-6 is a response to gp130 signaling and independent of TPO. Furthermore, human CD34(+) cells were subfractionated into two populations of IL-6R-negative (CD34(+) IL-6R-) and IL-6R-positive (CD34(+) IL-6R+) cells by fluorescence-activated cell sorting. The CD34(+) IL-6R- cells produced a number of Mks as well as Mk colonies in cultures supplemented with sIL-6R/IL-6 or TPO in the presence of SCF. In contrast, CD34(+) IL-6R+ cells generated much less Mks and lacked Mk colony forming activity under the same conditions. Collectively, the present results indicate that most of the human Mk progenitors do not express IL-6R, and that sIL-6R confers the responsiveness of human Mk progenitors to IL-6. Together with the presence of functional sIL-6R in human serum and relative unresponsiveness of human Mk progenitors to IL-6 in vitro, current results suggest that the role of IL-6 may be mainly mediated by sIL-6R, and that the gp130 signaling initiated by the sIL-6R/ IL-6 complex is involved in human megakaryopoiesis in vivo.

Antigens, CD↗