Biomedical subjects

T Yamauchi

Publications and source records attributed to T Yamauchi.

At least 235 records · Page 13Linked to original sources

PubMed1997

Parallel polarization electron paramagnetic resonance studies of the S1-state manganese cluster in the photosynthetic oxygen-evolving system.

Magnetic properties of the S1-state manganese cluster in the oxygen-evolving photosystem II were studied by parallel polarization electron paramagnetic resonance spectroscopy. Dark minus light spectra gave rise to a broad S1-state signal with a g value of about 4.9 [Dexheimer, S. L., Klein, M. P. (1992) J. Am. Chem. Soc. 114, 2821-2826]. Temperature variation of the signal intensity between 1.9 and 10 K observed in PS II with a sucrose buffer indicates that the signal originates from an excited state with a spin S of 1 with separation from the ground state (S = 0) of about 2.5 K. The S1-state signal was also observed in the sucrose buffer supplemented by 50% glycerol. However, no S1-state signal was detected by addition of 3% methanol or 30% ethylene glycol in the sucrose buffer, although illumination at 200 K in the presence of these alcohols induced the normal multiline S2 signal. Furthermore, modification of the Mn cluster by Cl- or Ca2+ depletion from PS II membranes failed to produce a detectable S1-state signal. A possible magnetic structure of the Mn cluster responsible for the generation of the S1-state signal is discussed on the basis of these observations.

Buffers↗

PubMed1997

Effects of discrimination learning on the rat striatal dopaminergic activity: a microdialysis study.

The prefrontal cortex (PFC) has anatomical and functional relationships with the striatum. In a previous study we showed that dopamine (DA) turnover in the PFC of rats is enhanced during the performance of a discrimination task. In the present study, we used an in vivo microdialysis method to examine whether DAergic activity in the striatum could also be altered by the discrimination task. The results showed a substantial and sustained suppression of DAergic activity during and after the discriminative behaviour. The fact that the discriminative performance induced opposite changes in DAergic activity in the striatum and the PFC is consistent with the results of biochemical studies, suggesting that the suppressed DA turnover in the striatum may be induced by the enhanced DAergic activity in the PFC during the discrimination task.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Effect of acid-base disturbances on aldosterone secretion in man.

The present study was carried out to elucidate whether changes in blood pH induced by administration of alkalinizing and acidifying agents influence aldosterone secretion in man. Since aldosterone secretion is known to be regulated by various factors such as the renin-angiotensin system, adrenocorticotropic hormone (ACTH), and serum potassium concentration, these indices were simultaneously measured during manipulation. Oral administration of tris hydroxymethyl aminomethane (THAM) resulted in a moderate but not significant decrease in serum aldosterone together with an increase in blood pH, whereas plasma renin activity (PRA) remained unchanged and serum potassium was elevated. ACTH and cortisol decreased significantly. Following CaCO3 ingestion, blood pH, serum potassium concentration, and hormones did not change significantly compared with before ingestion. NH4Cl ingestion showed a significant fall of blood pH and serum cortisol, on the other hand, aldosterone increased significantly compared with CaCO3 ingestion. Following NaHCO3 ingestion, serum aldosterone decreased with an increase in blood pH compared with before ingestion, while serum cortisol and PRA did not change significantly. The overall results of experiments using THAM, CaCO3, NaHCO3, and NH4Cl led to the conclusion that under acid-base disturbances a change in aldosterone can not be induced by either renin-angiotensin or ACTH. We suggest that under acid-base disturbances blood pH may be related, at least, in part to changes in aldosterone in humans.

Acid-Base Imbalance↗

PubMed1997

The contribution of Na+/H+ exchange to ischemia-reperfusion injury after hypothermic cardioplegic arrest.

BACKGROUND: Na+/H+ exchange has been reported to be one of the key mechanisms in myocardial ischemia-reperfusion injury. However, the effect of temperature on Na+/H+ exchange is not fully understood. METHODS: Sodium-propionate-induced cell swelling, an indicator of the function of the Na+/H+ exchanger, was measured in rat thymic lymphocytes. A Langendorff perfused rat heart model was also employed to investigate the effect of the pharmacologic inhibition of Na+/H+ exchange on the recovery of cardiac function after hypothermic ischemia. This was done using FR168888, an inhibitor of Na+/H+ exchange. RESULTS: In the in vitro study, rat lymphocytes were observed to swell at 17 degrees, 22 degrees, and 27 degrees C, indicating that the Na+/H+ exchanger remains functional even under hypothermic conditions. FR168888 was found to significantly inhibit Na+/H+ exchange-induced cell swelling, even at 17 degrees C. In the in vivo study, pretreatment with FR168888 was found to prevent the deterioration of ventricular function, even after 5 hours of hypothermic cardioplegic arrest. This was associated with a decrease in the reperfusion-induced elevation in resting tension. CONCLUSIONS: These results suggest that Na+/H+ exchange in the heart still occurs, even under hypothermic conditions, and contributes to reperfusion injury, even after hypothermic cardioplegic arrest.

Animals↗

PubMed1997

Expression of prostaglandin EP2 receptor mRNA in the rat spinal cord.

RT-PCR and an in situ hybridization analyses demonstrated expression of prostaglandin EP2 receptor mRNA in the subfield of the dorsal horn of the rat spinal cord. The intensive signals from the cells labeled with digoxigenin-11-dUTP were scattered through this region and they corresponded to neurons. EP2 receptor-mediated signal transduction is expected to play roles in modulating some neuronal functions such as transmission of nociceptive reaction or motor reflex.

Animals↗

PubMed1997

Intravenously administered macrophage colony-stimulating factor (M-CSF) specifically acts on the spleen, resulting in the increasing and activating spleen macrophages for cytokine production in mice.

IL-6 was transiently expressed in sera of mice after a bolus intravenous injection with LPS and it peaked 2 h later. Intravenous administration of M-CSF at 250 micrograms/kg/day for 5 days prior to an injection of 25 micrograms/kg of LPS elevated the serum IL-6 level 10-fold higher than that of mice which were not given M-CSF. Although M-CSF had no effect on the number of macrophages in alveoli and peritoneal cavity, it tripled the number of spleen macrophages and increased macrophage-progenitor cells 7-fold when injected intravenously. Spleen macrophages from M-CSF-injected mice produced 5-fold more IL-6 in response to LPS-stimulation in-vitro. However, M-CSF-injection had lesser effects on LPS-induced IL-6 production from liver, alveolar and peritoneal macrophages. Exogenously administered M-CSF was detected at higher concentration and for longer duration in the spleen than in any other organs examined. Spleen macrophages incubated in-vitro with more than 1000 U/ml of M-CSF for 3 days also produced more LPS-induced IL-6 than untreated cells. These results indicate that intravenously administered M-CSF not only enhances macrophage development in the spleen, but also primes mature macrophages for cytokine production.

Animals↗

PubMed1997

Familial occurrence of moyamoya disease.

There is extensive evidence that Moyamoya disease has a tendency for multifactorial inheritance, although the pathogenesis of Moyamoya disease is not clear. The authors report five cases showing familial occurrence of Moyamoya disease and analyse its clinical characteristics. In the past 15 years, we have encountered 68 cases of Moyamoya disease. Among these, 14 cases (10 females and four males, five family pedigrees, asymptomatic 1 case) of familial occurrence were observed. In this series, mother-to-child inheritance was observed in five cases, although there were no cases showing father-to-child inheritance. Ten patients were children with an initial onset of cerebral ischemia, at a mean age of 9.7 years. One mother was asymptomatic and two mothers had a past history of cerebral ischemia. Only one patient was a 37-year-old woman with clinical onset of intracerebral hemorrhage. There were no specific clinical characteristics in familial Moyamoya disease compared with those in sporadic Moyamoya disease.

Adult↗

PubMed1997

Electroconvulsive therapy for a schizophrenic patient with burns in the critical care centre.

Electroconvulsive therapy (ECT) for a schizophrenic patient with burns in the critical care centre is reported. The patient was a 26-year-old male. He had sustained burns over 45 per cent of his body during a suicide attempt. After admission to the critical care centre, he remained restless despite intensive therapy with neuroleptics. Three months after admission, ECT with muscle relaxation was administered in the critical care centre. After ECT, the patient became emotionally stable and cooperated with the subsequent burn treatment. ECT is available for burned patients along with somatic treatment in critical care centres.

Adult↗

PubMed1997

Differentiation induction in non-lymphocytic leukemia cells upon treatment with mizoribine.

Inosine-5'-monophosphate (IMP) dehydrogenase catalyzes the rate-limiting reaction of guanine nucleotide biosynthesis and has been implicated in the reaction of cell growth and differentiation. We examined the ability of mizoribine, an IMP dehydrogenase inhibitor, to induce differentiation in HL-60 and U937 cells as well as in fresh leukemic blast cells from patients with non-lymphocytic leukemia. Treatment with mizoribine reduced intracellular GTP levels and induced morphologic and functional differentiation in these two cell lines in a dose-dependent manner. HL-60 and U937 cells developed polymorphic nuclei and macrophage-like cytoplasm, respectively, as well as expression of CD11b and CD14 antigens and the ability to oxidize NBT. These changes became evident when intracellular GTP levels decreased to approximately 30% of untreated controls and were abrogated by addition of guanosine to the media. However, in fresh leukemic cells, the cells showing maturation in response to mizoribine were limited in those derived from two of ten patients having non-lymphocytic leukemia. These findings suggest mizoribine could induce differentiation in HL-60 and U937 cells through a decrease of intracellular GTP levels. Further study is required to determine its clinical use in patients with acute non-lymphocytic leukemia.

Adult↗

PubMed1997

Difference in serum-induced prostacyclin production by cultured aortic and capillary endothelial cells.

Prostacyclin (PGl2) generated by vascular endothelial cells play an important role in the maintenance of vessel wall homeostasis. Human plasma-derived serum (PDS) stimulated PGl2 synthesis by both cultured bovine aortic endothelial cells (BAEC) and adrenal capillary endothelial cells (BCEC), but the PGl2 response of the latter cells was far smaller. When BAEC were cultured with a high concentration of glucose (400 mg/dl), the PGl2 synthesis induced by 20% PDS was significantly lower than in the culture with a physiological concentration of glucose (100 mg/dl) (258 +/- 45 pg/10(4) cells/h vs. 402 +/- 52 pg/10(4) cells/h, n = 4, P < 0.05). On the other hand, there was no significant difference in the PDS-induced PGl2 synthesis between BCEC cultured with high and physiological concentrations of glucose. Additionally, 10% PDS obtained from patients with non-insulin dependent diabetes mellitus (n = 6) stimulated significantly less PGl2 synthesis than that from healthy subjects (n = 4) in the case of both BAEC (133 +/- 27 pg/10(4) cells/h vs. 402 +/- 38 pg/10(4) cells/h, P < 0.05) and BCEC (72 +/- 15 pg/10(4) cells/h vs. 118 +/- 12 pg/10(4) cells/h, P < 0.05), with the difference in PGl2 synthesis being smaller for BCEC. These findings indicate that the PDS-induced PGl2 synthesis differs between cultured vascular endothelial cells from large and small vessels with the decrease in PGl2 by diabetic PDS and high glucose being more marked for BAEC than BCEC.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

Dissociation of bone formation markers in bone metastasis of prostate cancer.

To clarify the meaning and clinical value of bone formation markers in bone metastasis from prostate cancer, we investigated the bone formation markers carboxy-terminal propeptide of type I procollagen (PICP), bone-specific alkaline phosphatase (BA1-p) and osteocalcin, so-called bone gla protein (BGP) in 43 prostate cancer patients with and 46 patients without overt bone metastasis. Patients with bone metastasis were evaluated repeatedly by bone scan at intervals of 3-6 months. The expression patterns of bone formation markers in patients with progression of bone metastasis became dissociated; BA1-p and PICP were elevated in patients with progression of bone metastasis but BGP was not. Instead, BGP showed slight elevation in patients with improvement and complete remission of bone metastasis. PICP, BA1-p and BGP are all bone formation markers, but each marker appears in a different phase of bone formation: PICP appears in proliferation phase, BA1-p appears in matrix maturation phase and BGP appears in late bone formation phase. Our findings that BGP was not elevated in progression of bone metastasis and that it increased slightly with improvement and complete remission of bone metastasis may imply that the bone formation that occurs in blastic bone metastasis is different from normal bone formation.

Aged↗

PubMed1997

A 39,X/40,XY true hermaphrodite mouse with normal ovarian function.

A cryptorchid mouse with a 39,X/40,XY chromosome constitution was identified among 414 offspring born in the departmental XO mouse breeding colony. This mouse had a small testis on the left, with no sign of spermatogenesis, and a normal ovary on the right with several corpora lutea.

Animals↗

PubMed1997

Analysis of the substrate binding site and carboxyl terminal region of vacuolar H+-pyrophosphatase of mung bean with peptide antibodies.

Vacuolar H+-translocating inorganic pyrophosphatase is a single-protein enzyme and uses a simple substance as an energy donor. Functional domains of the enzyme were investigated by using antibodies specific to peptides corresponding to the putative substrate-binding site (DVGADLVGKVE) in the hydrophilic loop and the carboxyl terminal part. The antibody to the former peptide clearly reacted with the pyrophosphatases of different plant species, and strongly inhibited the hydrolytic activity of the purified enzymes and the proton pumping activity of membrane vesicles. These results indicate that the sequence functions as an actual substrate-binding site and is a common motif. The antibody to the carboxyl terminal part reacted only to the mung bean enzyme, suppressing its hydrolytic and proton pumping activities. The results suggest that the carboxyl terminus is exposed to the cytosol and is close to the catalytic site. H+-Pyrophosphatase hydrolyzed triphosphate and tetraphosphate at low rates. Phytic acid, myo-inositol hexaphosphate, inhibited the enzyme even in the presence of Mg2+. The concentration for 50% inhibition was 0.15 mM. The inhibition of H+-PPase by dicyclohexyldiimide was partly reversed by Mg2+. The catalytic site and the membrane topology of the enzyme are discussed.

Amino Acid Sequence↗

PubMed1997

Nipple-areola reconstruction with a dermal-fat flap and rolled auricular cartilage.

In reconstruction of the nipple-aerola complex, it is important to maintain nipple projection. The conventional methods of reconstructing the nipple using local skin flaps maintain the feature for a certain period postoperatively, but the height of the nipple eventually flattens as the scars soften over time. Considering that sustaining the feature of the nipple is most important for achieving and maintaining nipple projection, we have therefore devised a new operative technique. Rolled auricular cartilage is placed in the center of the bridge of the dermal base and is wrapped with bilobed dermal-fat flaps. This technique has the following advantages: The cartilage produces and sustains a good form of the feature without subcutaneous depression because the cartilage is supported by the bridge of the dermal base. Since the dermal base forms a bridge, the method is safe, maintains good circulation, and does not lead to any necrosis in the flap. This method also was compared with a method in which the rolled auricular cartilage is wrapped with a trilobed dermal fat flap.

Adult↗

PubMed1997

Cisplatin, vincristine, methotrexate, peplomycin, etoposide (COMPE) therapy for disseminated germ cell testicular tumors.

BACKGROUND: The advent of cisplatin rendered disseminated testicular germ cell tumor an often curable malignant disease. Patients with a heavy metastatic burden, however, remain poor risks; furthermore, many patients experience nausea or other adverse events. This paper reports a trial of a cisplatin-based (COMPE) combination chemotherapy regimen based on synchronization theory. METHODS: Twenty patients with disseminated germ cell testicular tumors were treated with COMPE; any residual tumor mass was surgically resected. RESULTS: Seventeen patients (85%) achieved complete remission by chemotherapy. The actuarial overall and cause-specific 3-year survival rates were 89% and 94%, respectively. In the subset of 16 "good-risk" patients, all remain alive after a median follow-up of 43 months. Complications were quite tolerable, with nephrotoxicity in particular being extremely mild. CONCLUSION: COMPE is an effective chemotherapy regimen in patients with disseminated germ cell testicular tumors. Complications arising from this therapy are mild.

Adult↗

PubMed1997

Influence of intravesical bacillus Calmette-Guérin therapy on systemic immunological status.

BACKGROUND: Intravesical bacillus Calmette-Guérin (BCG) therapy for superficial bladder cancer induces obvious local immunological responses. The purpose of this study was to examine the systemic immunological influences induced by intravesical BCG therapy. METHODS: We measured peripheral blood lymphocyte subsets (PBLS) and monocyte counts in 30 patients with superficial bladder carcinoma by two-colored flow cytometry before, during, and after intravesical BCG treatment. Comparisons were made between 24 good treatment responders and 6 poor responders. RESULTS: From 3 to 12 months after the beginning of treatment, PBLS and monocyte counts changed, as evidenced by an increase of suppressor T cells and a decrease of helper T cells. The good responders had higher cell counts than the poor responders, with differences in cell counts between good and poor responders more marked 1 month after beginning treatment, particularly of natural killer cells, cytotoxic T cells, and inducer T cells. These differences disappeared 3 months after the onset of treatment. CONCLUSION: Intravesical BCG therapy caused a marked and persistent alteration of the systemic immunological status.

Administration, Intravesical↗

PubMed1997

Continuous low-dose NO inhalation does not prevent monocrotaline-induced pulmonary hypertension in rats.

We determined whether vasodilator doses of inhaled nitric oxide (NO) prevented the progression of pulmonary hypertension (PH) and vascular changes in monocrotaline-induced PH. Short-term NO inhalation in rats 3 wk after the injection of monocrotaline reduced mean pulmonary artery pressure (PAP) from 30.7 +/- 2.2 (SE) to 26.4 +/- 1.4 mmHg at 10 parts per million (ppm) and from 30.2 +/- 1.3 to 25.8 +/- 1.4 mmHg at 40 ppm. There were no differences among rats exposed to air only and rats exposed to 10 ppm of NO for 19 days after a single subcutaneous injection of monocrotaline, in mean PAP (34.3 +/- 1.9 mmHg air vs. 32.8 +/- 1.4 mmHg NO), right ventricular hypertrophy (RVH), medial wall thickness (MWT) of muscular arteries, and the percentage of muscularized arteries at alveolar wall (%AW) and duct (%AD) level. Additional groups exposed to air only and 40 ppm of NO for 19 days again showed no difference in mean PAP, RVH, MWT, and %AD, except that this dose slightly reduced %AW (60.6 +/- 3.4% air vs. 46.9 +/- 5.2% NO, P = 0.04). Urine nitrate (NO3) level was higher in rats that had inhaled NO. In contrast to chronic hypoxic PH, vasodilator doses of NO inhalation did not prevent the development of PH in this malignant form of experimental PH.

Administration, Inhalation↗

PubMed1997

In vitro macro- and microautoradiographic localization of V1 and V2 receptors in the rat kidney using OPC-21268 and OPC-31260.

To elucidate the precise localization of vasopressin (VP) V1 and V2 receptors in the kidney, we utilized in vitro macroautoradiography (macro-ARG) and microautoradiography (micro-ARG) of these receptors in Wistar rat kidneys. This was done by using OPC-21268 and OPC-31260, two newly developed selective V1 (OPC-21268) and V2 (OPC-31260) receptor antagonists. For macro-ARG, 10-microm kidney sections were incubated with Tris-HCl buffer containing [3H]-VP with or without unlabeled ligand (VP, OPC-21268, or OPC-31260) at 20 degrees C for 40 min. These sections were then loaded into X-ray cassettes with Hyperfilm-[3H] and exposed in the dark for 2 months. The autoradiograms were quantitatively analyzed by using the research analysis system RAS 1,000; the V1 and V2 receptors were quantitated by subtracting the nonspecific binding (incubated with OPC-21268 and OPC-31260, respectively) from the total binding. To assess a more precise localization of the V1 and V2 receptors, we also investigated the micro-ARG of the renal V1 and V2 receptors by dipping the kidney section slides used for macro-ARG into a photographic emulsion and observing the receptors under light microscopy. [3H]-VP binding to the rat kidney was completely displaced by unlabeled excess VP, but not by unlabeled angiotensin II, indicating that [3H]-VP binding was specific for VP receptors. Computerized quantification showed that V2 receptors, visualized by OPC-31260, were the predominant type of VP receptor in the kidney. Conversely, V1 receptors, visualized by OPC-21268, were fewer in number. V1 receptors were partly localized to the glomerulus, cortical vessels, interstitial cells, and the medullary vessels. The V2 receptors localized to the collecting ducts and medullary tubules. Our findings indicated that renal V1 and V2 receptors can be detected by in vitro macro- and micro-ARG by using OPC-21268 and OPC-31260.

Animals↗