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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

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

Expression of type II iodothyronine deiodinase in brain tumors.

Type II iodothyronine deiodinase (DII) messenger ribonucleic acid (mRNA) and its activity have been demonstrated in human normal brain. Although DII activity has been demonstrated in brain tumors, expression of DII mRNA has not been studied in these tumors. To investigate the mechanisms involved in the expression of DII activity in brain tumors, we studied DII mRNA and DII activity in astrocytoma (two cases), glioblastoma (three cases), and oligodendroglioma (one case). DII mRNA, the size of which was indistinguishable from that in control cerebral cortical tissue, was demonstrated in all of the brain tumors tested, although the intensity of the hybridization signal showed wide variation among the tumors. DII activity was also detected in all tumors. DII mRNA and DII activity were highest in the tissue from oligodendroglioma. A significantly positive correlation was observed between DII mRNA and DII activity in these tumors (r = 0.94; P < 0.01), suggesting that DII expression in brain tumors is regulated at the pretranslational level. The present results demonstrate, for the first time, that DII mRNA as well as DII activity are expressed in brain tumors, and that DII mRNA is significantly correlated with DII activity in those tissues.

Adult↗
PubMed2000

Michael-type reaction of ethyl bromodifluoroacetate with alpha,beta- unsaturated carbonyl compounds in the presence of copper powder.

We have reported that the reaction of ethyl bromodifluoroacetate (1) with alkenyl iodides in the presence of copper powder gives ethyl alkenyldifluoroacetates. As an extension of this reaction, reaction of 1 with Michael acceptors in the presence of copper powder was examined and found to give 1,4-addition products selectively, unless the acceptor has a group stabilizing a radical intermediate, such as a phenyl group.

Copper↗
PubMed2000

Superoxide dismutase activity of iron(II)TPEN complex and its derivatives.

Superoxide is involved in the pathogenesis of various diseases, such as inflammation, ischemia-reperfusion injury and carcinogenesis. Superoxide dismutases (SODs) catalyze the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, and can protect living cells against the toxicity of free radicals derived from oxygen. Thus, SODs and their functional mimics have potential value as pharmaceuticals. We have previously reported that Fe(II)tetrakis-N,N,N',N'-(2-pyridylmethyl)ethylenediamine (Fe(II)TPEN) has an excellent SOD activity (IC50 = 0.5 microM) among many iron complexes examined (J. Biol. Chem., 264, 9243-9249 (1989)). Fe(II)TPEN can act like native SOD in living cells, and protect Escherichia coli cells from free radical toxicity caused by paraquat. In order to develop more effective SOD functional mimics, we synthesized Fe(II)TPEN derivatives with electron-donating or electron-withdrawing groups at the 4-position of all pyridines of TPEN, and measured the SOD activities and the redox potentials of these complexes. Fe(II) tetrakis-N,N,N',N'-(4-methoxy-2-pyridylmethyl)ethylenediamine (Fe(II)(4MeO)4TPEN) had the highest SOD activity (IC50 = 0.1 microM) among these iron-based SOD mimics. In addition, a good correlation was found between the redox potential and the SOD activity of 15 Fe(II) complexes, including iron-based SOD mimics reported in the previous paper (J. Organometal. Chem., in press). Iron-based SOD mimics may be clinically applicable, because these complexes are generally tissue-permeable and show low toxicity. Therefore our findings should be significant for the development of clinically useful SOD mimics.

Ethylenediamines↗
PubMed2000

Tissue doppler imaging of left and right ventricles in normal children.

Tissue Doppler imaging is a new ultrasound technology that derives measurements of contraction and relaxation velocities directly from the myocardium. However, data on myocardial velocities by using tissue Doppler imaging have not been established in normal children. In 48 normal children, myocardial velocities were measured using tissue Doppler imaging at three different sites (base, middle, and apex) in the left and right ventricles and the interventricular septum. In the left ventricular wall, the peak myocardial velocities during early diastole (peak E), during atrial contraction (peak A), and during systole (peak S) waves decreased gradually between the base and apical sites, whereas the ratio of E to A waves (peak E/A wave ratio) did not change among the 3 segments. Similar findings were obtained from the myocardial velocities in the right ventricle and the interventricular septum. A systolic and diastolic velocity gradient was also observed between the different ventricular walls. Significant correlations of the tissue Doppler parameters with age or heart rate were observed. In the left ventricle, the peak E wave demonstrated a stronger relation with age (r=0.77) than with heart rate (r=-0.65). The peak A wave did not change with age but correlated with heart rate. The peak E/A wave ratio showed a weaker relation with age (r=0.54) than with heart rate (r=0.62). The peak S wave was related to age (r=0.65) and to a lesser extent to heart rate (r= -0.51). Similar relationships of tissue Doppler parameters with age or heart rate were observed for the right ventricle and interventricular septum. The heterogeneous pattern and age- and heart-rate-related changes in normal myocardium demonstrated in this study must be taken into account when attempting to identify altered regional myocardial function with tissue Doppler echocardiography.

Adolescent↗
PubMed2000

Tumor-like splenic extramedullary hematopoiesis in a patient with myelofibrosis.

A 61-year-old woman, who was diagnosed in 1982 as having polycythemia vera, was admitted to our hospital in July 1998 because of a splenic tumor in an enlarged spleen due to myelofibrosis. As it was difficult to identify the etiology of the splenic tumor, partial splenectomy was carried out. The resected tumor proved to be an extremely proliferative lesion as the result of extramedullary hematopoiesis. Since it is difficult to diagnose the etiology of splenic tumor, the collection and analysis of reports of relevant cases may well facilitate diagnosis.

Diagnosis, Differential↗
PubMed2000

Effects of progesterone on the elevation of tail skin temperature in ovariectomized rats.

We examined the effects of progesterone on the elevation of tail skin temperature (TST) in ovariectomized rats and compared them with those of estradiol. Progesterone showed only insignificant effects on the TST elevation, whereas estradiol showed complete inhibition. The TST elevation induced by ovariectomy is caused by estradiol deficiency, but progesterone plays little or no role.

Animals↗
PubMed2000

Inhibitory effect of lactoferrin on the adhesion of Prevotella nigrescens ATCC 25261 to hydroxyapatite.

Prevotella nigrescens ATCC 25261 (P. nigrescens) cells adhere well to hydroxyapatite treated with citrate (CHA), but the attachment is drastically inhibited by lactoferrin (LF). To determine the nature of the iron-free LF responsible for inhibiting P. nigrescens cell attachment, this study tested the duration and frequency of LF treatment of CHA and the effects of divalent and trivalent ferric ions. The inhibitory effect on the attachment of P. nigrescens was somewhat higher with bovine LF than human LF. Apo LF effectively inhibited P. nigrescens cell attachment to CHA, and almost abolished attachment at a concentration of 0.4 mg/ml. Fe3+ saturated LF was unable to inhibit attachment, whereas Fe2+ showed a slight effect under the same conditions. The LF absorbed rapidly to CHA in less than 10 min. With a lower concentration (0.1 mg/ml) of LF, only three treatments of CHA were required for the maximum inhibition of P. nigrescens cell attachment. The quantity of LF adsorbed to the hydroxyapatite (HA) and to P. nigrescens cells was determined by use of [3H]-LF. Approximately 25 micrograms of LF protein adsorbed to 5 mg of HA at saturation, and approximately 0.25 microgram of LF did so to the 6 x 10(8) cells.

Adsorption↗
PubMed2000

[Anesthetic management for a patient with spondyloepiphyseal dysplasia congenita].

An 11-year-old girl with spondyloepiphyseal dysplasia congenita in the spine was scheduled for virectomy under general anesthesia. She had slight scoliosis in the thoracic and lumbar spine, moderate funnel chest and slight thoracic kyphosis. Preoperative laboratory data were within normal range and her intelligence was normal. Her Mallanpathi's score, however, was Grade 3 and effective mandibular length/posterior depth of mandible ratio was 3.48 on the lateral view of head X-ray. From these data, difficult intubation was expected. Although anesthesia was induced uneventfully using thiamylal and vecuronium, her vocal cord was not visualized under laryngoscope. Using cricoid pressure procedure, slightly left-shifted vocal cord was exposed. However a 26 Fr. size endotracheal tube without cuff was too large and finally a 22 Fr. tube was inserted. During the operation patient's general condition was stable and the operation was finished without any episodes. She did not have any complications in the postoperative period. In a case of SDC, pathological changes in laryngotracheal resion should be examined and evaluated preoperatively and difficult intubation should also be always taken into account.

Anesthesia, General↗
PubMed2000

New PCR primer pairs specific for Candida dubliniensis and detection of the fungi from the Candida albicans clinical isolates in Japan.

The genetic patterns of Candida dubliniensis, including type strain, were analyzed by random amplified polymorphic DNA (RAPD) method in comparison with those of reference Candida albicans genotypes A, B and C strains. This RAPD pattern analysis showed that the patterns of two strains of C. dubliniensis including the type strain are very similar to the three oligo PCR primers used, but different from other C. albicans genotypes A, B and C strains with most of the PCR primers tested. The RAPD band considered to be specific for C. dubliniensis in one oligo primer was extracted and sequenced. Based on the sequence information (417-bp), two new PCR primer pairs specific for C. dubliniensis were prepared. The survey of 58 strains of Candida clinical isolates using these newly prepared PCR primer pairs identified as C. albicans in Japan suggested the presence of one strain of C. dubliniensis. The phenotypic characteristics and the sequence analysis of the variable D1/D2 domain of the large subunit (26S) ribosomal DNA of the strain confirmed that it belongs to C. dubliniensis. The usefulness and specificity of these PCR primer pairs for the identification of C. dubliniensis are discussed.

Base Sequence↗
PubMed2000

Persistence of cryptococcal antigenemia in an infected dog and uninfected rabbits.

A case of cryptococcosis in a dog is reported. The titers of polysaccharide antigen in sera were monitored by latex agglutination (LA) tests during and after treatment with antifungal therapy. Although the LA titers decreased in response to therapy, it took about 3.5 years to achieve a negative LA test. To model the persistence of cryptococcal polysaccharides, we examined the clearance of antigen from the blood of rabbits injected with sterile, cryptococcal capsular polysaccharide isolated from culture supernatant. The distribution half-lives were between 2.6 and 3.9 days and the elimination half-lives were between 10.4 and 39 days. These results suggest that polysaccharide antigen may be stored in tissues. However, we think that slow clearance of antigen cannot explain the extraordinarily slow clearance found in this dog, and that prolonged survival of Cryptococcus neoformans is a more plausible explanation.

Animals↗
PubMed2000

Requirement of protamine for maintaining nuclear condensation of medaka (Oryzias latipes) spermatozoa shed into water but not for promoting nuclear condensation during spermatogenesis.

Protamine is an arginine-rich basic protein found in the sperm nuclei of many vertebrates, but its actual roles in spermatozoa remain to be elucidated. In this study, we investigated the physiological roles of protamine by examining protamine-less spermatozoa produced in vitro in the presence of the transcriptional inhibitor actinomycin D. Even under inhibited transcription, medaka spermatocytes underwent meiosis and differentiated into spermatozoa with a condensed nucleus and an elongated flagellum. Using a newly produced anti-medaka protamine antibody, we confirmed the absence of protamine protein in the spermatozoa differentiated in the presence of actinomycin D. These findings clearly indicate that sperm nuclear condensation in medaka is independent of protamine. Since medaka spermatozoa are shed into water upon natural fertilization, we also investigated the roles of protamine by comparing the differences between the nuclear morphology of protamine-equipped and protamine-less spermatozoa immersed in water. The nuclei without protamine more rapidly swelled than did those with protamine and completely broke down within 10 min, whereas more than 80% of the sperm nuclei with protamine resisted the disruption under similar conditions. These findings strongly suggest that a physiological role of protamine in medaka spermatozoa is to protect the ejaculated spermatozoa against the disruption by low osmotic pressure until arrival at the eggs for successful fertilization.

Animals↗
PubMed2000

Biological markers of alcoholism with respect to genotypes of low-Km aldehyde dehydrogenase (ALDH2) in Japanese subjects.

BACKGROUND: Although the mutant low-Km acetaldehyde dehydrogenase (ALDH2) allele (ALDH2(2)) with reduced capacity to metabolize acetaldehyde offers biological protection against alcoholism and subsequent alcohol-induced organ damage in many individuals, a significant proportion of individuals with heterozygote of the normal and mutant ALDH2 gene (ALDH2(1)/2(2)) consume excessive amounts of alcohol. Indeed, it has been postulated that habitual drinkers with ALDH2(1)/2(2) may be at a higher risk for alcoholic liver disease than those with ALDH2(1)/2(1). In this study, we determined how representative biological markers of alcoholism (gamma-glutamyltransferase [GGT], carbohydrate-deficient transferrin [CDT], and the mean corpuscular volume of erythrocytes [MCV]) differ with respect to the ALDH2 genotypes in Japanese habitual drinkers. METHODS: We obtained genomic DNA samples from 227 Japanese men with various drinking habits. ALDH2 genotypes were determined by allele-specific polymerase chain reaction. GGT, CDT, and MCV were determined and compared between ALDH2(1)/2(1) and ALDH2(1)/2(2) habitual drinkers who consumed more than 66 g of alcohol per day for more than 5 years. We measured CDT by anion-exchange chromatography followed by turbidity immunoassay by using a commercially available assay kit (Axis %CDT TIA). RESULTS: CDT levels were comparable between the two groups. GGT activities were significantly greater in ALDH2(1)/2(1) than in ALDH2(1)/2(2) habitual drinkers (81 +/- 85 vs. 53 +/- 40 IU/liters, p < 0.02). MCV values, on the other hand, were significantly larger in ALDH2(1)/2(2) than in ALDH2(1)/2(1) subjects (98.2 +/- 5.8 vs. 95.8 +/- 4.2 fl, p = 0.02). When we used elevation of either CDT or GGT to detect habitual drinking in ALDH2(1)/2(1) and 2(1)/2(2) subjects, the sensitivities were 57% and 46%, respectively. CDT levels were similar between habitual drinkers with normal aspartate aminotransferase levels and those with elevated levels. CONCLUSION: GGT and MCV, but not CDT, differ with respect to the ALDH2 genotypes in Japanese male habitual drinkers. ALDH2 genotypes should be considered when interpreting data on biological markers of alcoholism.

Adult↗
PubMed2000

Effect of dietary cardiac glycosides on blood pressure regulation in rats.

To investigate the possible physiological significance of dietary cardiac glycosides in blood pressure regulation, the blood pressure of normal Sprague Dawley rats raised on a regular diet, which naturally contains large amounts of Na+-pump inhibitors, was compared with that of rats on a purified synthetic diet, which contains no Na+-pump specific inhibitors, and with that of rats on a synthetic diet supplemented with 10 microg x mL(-1) ouabain or 10 microg x mL- convallatoxin in the drinking water. After 6 weeks on the synthetic diet, the systolic blood pressure in the synthetic diet group was significantly elevated (145 +/- 5 vs. 128 +/- 4 mmHg, P < 0.05). At 10 weeks it reached a plateau (154 +/- 3 vs. 122 +/- 3 mmHg, P < 0.05). Plasma renin activity and Na+ level were significantly higher in animals fed synthetic diets than in the regular diet group (P < 0.01). Administration of either losartan or lisinopril or a switch to a low salt synthetic diet (0.03% sodium) normalized the synthetic diet-induced high blood pressure. Supplementation of the synthetic diet with the cardiac glycosides delayed the onset of the increase in blood pressure for 4 weeks. Plasma aldosterone levels were approximately doubled in the cardiac glycoside-treated groups. Higher plasma Na+ levels and hematocrit values present in the synthetic diet group were normalized by the glycoside supplements. These results suggest that supplemental dietary cardiac glycosides exert bidirectional effects on blood pressure regulation through actions that modulate extracellular fluid and electrolyte balance.

Animals↗
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

Risk factors for ischemic heart disease in an urban area of Japan: a case-control study in AMHTS.

OBJECTIVES: In Japan controversy exists as to whether or not the risk factors for ischemic heart disease (IHD) are the same as in western countries. We conducted a case-control study on IHD to clarify the risk factors in males in an urban area of Japan using our automated multiphasic health testing and services (AMHTS) system. METHOD: Cases were the clients who took the health check-up between January 1987 and July 1994 and had onset of IHD after the check-up. For each case five clients were selected as controls by conditional matching. The check-up data were compared between cases and controls 11 years, 6 years and just before the onset of the heart diseases. RESULTS: The statistically significant items were as follows: (1) Eleven years before the onset: Total cholesterol (T-Chol) for myocardial infarction (MI), and fasting blood sugar (FBS) for angina pectoris (AP). (2) Six years before the onset: T-Chol, electrocardiographic (ECG) findings and the complaint of palpitation or breathlessness for MI, and FBS and palpitation or breathlessness for AP. (3) Just before the onset: T-Chol, the complaint of chest pain, FBS, smoking index and hypertensive status for MI and palpitation or breathlessness, ECG findings, chest pain, systolic blood pressure and erythrocyte sedimentation rate at 60 minutes for AP. In conclusion, the risk factors for MI in males in an urban area of Japan are the same as in western countries. The most significant risk factor for AP in males in an urban area of Japan is fasting blood sugar.

Adult↗