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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 37 records · Page 2Linked to original sources
PubMed2004

Fast sound in expanded fluid Hg accompanying the metal-nonmetal transition.

The dynamic structure factor S(Q,omega) of expanded fluid Hg has been measured up to the metal-nonmetal transition region at 9.0 g cm(-3) (1723 K and 1940 bars) using high-resolution inelastic x-ray scattering, at momentum transfers, Q, from 0.2 to 4.8 A(-1). Analysis in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The effective sound velocity at 9.0 g cm(-3) estimated from the dispersion relation is triple the ultrasonic sound velocity. The present result suggests the existence of fast sound in expanded fluid Hg accompanying the metal-nonmetal transition.

Mercury↗
PubMed2004

Randomized trial of cefepime monotherapy or cefepime in combination with amikacin as empirical therapy for febrile neutropenia.

A multicenter open randomized trial was conducted to compare cefepime monotherapy with cefepime/amikacin combination (dual) therapy in treating febrile neutropenic patients with hematologic disorders. Among the 189 evaluable patients, 5.8% had microbiologically and 10.6% had clinically documented infections. Excellent response was seen in 32.6% and 45.7% of monotherapy and dual therapy recipients, respectively, at day 3 (P=.065). At day 3, patients with neutrophil counts of <500/ mu L receiving dual therapy had a better response than did those receiving monotherapy (45% vs. 27.6%; P=.024). The same was true for patients with leukemia. Adverse events were minimal, and early death was observed in 7 patients in the dual therapy group and 5 patients in the monotherapy group. Overall, cefepime monotherapy is as effective as dual therapy for the initial treatment of febrile neutropenic patients. Further study is warranted for patients with severe neutropenia and leukemia who may benefit from dual therapy.

Amikacin↗
PubMed2004

Initial empirical antimicrobial therapy: duration and subsequent modifications.

Neutropenic patients at low risk of complications can receive oral ciprofloxacin or levofloxacin as outpatients. These agents plus amoxicillin/clavulanate or other penicillins, cephalosporins, or penem compounds are indicated to treat infections with gram-positive organisms in patients with oral mucositis or skin lesions. Parenteral fourth-generation cephalosporins or carbapenems can be given. For high-risk patients, monotherapy with cefepime or the carbapenems can be used. Methicillin-resistant Staphylococcus aureus should be treated with vancomycin or teicoplanin. For combination therapy, a third- or fourth-generation cephalosporin or carbapenem plus an aminoglycoside is desirable. Defervescence in 3-5 days for at least 7 days is suggested for subsequent management. Initial antibiotic(s) can be continued for patients who remain in good condition. For persistent fever after 3-5 days, the patient should be thoroughly reassessed. An aminoglycoside should be added for those initially treated with monotherapy. The initial cephalosporin can be changed to another cephalosporin or a carbapenem, or the initial carbapenem can be changed to a broad-spectrum cephalosporin. For patients initially receiving dual therapy, the cephalosporin or carbapenem can be changed as with monotherapy, whereas the initial aminoglycoside should be changed to another aminoglycoside or intravenous ciprofloxacin.

Algorithms↗
PubMed2004

Combination phase I study of nedaplatin and gemcitabine for advanced non-small-cell lung cancer.

To establish the toxicities and maximum tolerated dose (MTD) of nedaplatin with gemcitabine, and to observe their antitumour activity, we conducted a combination phase I study in advanced non-small-cell lung cancer (NSCLC). Patients received nedaplatin (60-100 mg m(-2) given intravenously over 90 min) on day 1, and gemcitabine (800-1000 mg m(-2) given intravenously over 30 min) on days 1, 8, every 3 weeks. In total, 20 patients with locally advanced or metastatic NSCLC who received no prior chemotherapy or one previous chemotherapy regimen were enrolled. The most frequent toxicities were neutropenia and thrombocytopenia; nonhaematological toxicities were generally mild. Three out of six patients experienced dose-limiting toxicities (neutropenia, thrombocytopenia and delayed anaemia) at dose level 4, 100 mg m(-2) nedaplatin with 1000 mg m(-2) gemcitabine, which was regarded as the MTD. There were three partial responses, for an overall response rate of 16.7%. The median survival time and 1-year survival rate were 9.1 months and 34.1%, respectively. This combination is well tolerated and active for advanced NSCLC. The recommended dose is 80 mg m(-2) nedaplatin with 1000 mg m(-2) gemcitabine. This combination chemotherapy warrants a phase II study and further evaluation in prospective randomised trials with cisplatin- or carboplatin-based combinations as first-line chemotherapy for advanced NSCLC.

Adult↗
PubMed2004

Peptide synthesis through evolution.

Ribosome-catalyzed peptide bond formation is a crucial function of all organisms. The ribosome is a ribonucleoprotein particle, with both RNA and protein components necessary for the various steps leading to protein biosynthesis. Evolutionary theory predicts an early environment devoid of complex biomolecules, and prebiotic peptide synthesis would have started in a simple way. A fundamental question regarding peptide synthesis is how the current ribosome-catalyzed reaction evolved from a primitive system. Here we look at both prebiotic and modern mechanisms of peptide bond formation and discuss recent experiments that aim to connect these activities. In particular, RNA can facilitate peptide bond formation by providing a template for activated amino acids to react and can catalyze a variety of functions that would have been necessary in a pre-protein world. Therefore, RNA may have facilitated the emergence of the current protein world from an RNA or even prebiotic world.

Biological Evolution↗
PubMed2004

Changes in coagulation condition, cytokine, adhesion molecule after repair of type A aortic dissection.

OBJECTIVE: Because residual dissection often exists even after the repair of a type A dissection, we evaluated coagulation conditions, cytokine levels, and adhesion molecule levels in mid-term follow up after repair of type A dissections. METHODS: Thrombin-antithrombin III complex (TAT), D-dimer, soluble interleukin-2 receptor (sIL-2R), soluble intercellular adhesion molecule (sICAM)-1, and type III procollagen peptide (PIIIP) were measured in 12 patients (mean age=63 years) following the repair of a type A aortic dissection at 6-82 months after repair (median=33 months). RESULTS: In the chronic phase, TAT and D-dimer were significantly higher in patients following the repair of a type A dissection compared to healthy controls (TAT; 12+/-8 vs. 2.5+/-1.2 ng/ml, P = 0.0001, D-dimer; 779+/-1384 vs. 104+/-46 U/ml, P = 0.0001). Cytokine was significantly higher in the affected patients (sIL-2R; 556+/-205 vs. 398+/-132 U/ml, P = 0.003, sICAM-1; 255+/-131 vs. 211+/-48 ng/ml, P = 0.136). Collagen turnover (PIIIP) showed a significantly higher value in the affected patients (0.80+/-0.32, vs. 0.58+/-0.13 U/ml, P = 0.002). sIL-2R, sICAM-1 and PIIIP showed a negative correlation with the follow-up period (sIL-2R; r = -0.733, P = 0.0067, sICAM-1; r = -0.61, P = 0.035, PIIIP; r = -0.692, P = 0.0126). We found a positive correlation between aortic size and TAT (r = 0.644, P = 0.0238, n = 12) as well as with D-dimer (r = -0.7831, P = 0.0106, n = 12) and TAT showed significantly higher values in the residual dissection group compared to those without residual dissection (16.6+/-7.9 vs. 7.45+/-4.75 ng/ml, P = 0.035). CONCLUSION: Hypercoagulation conditions continued even after repair. Both TAT and D-dimer would be good indices for following up patients having repaired aortic dissections. Furthermore, cytokine, adhesion molecules, and collagen turnover would return to a stable state unless impairment and expansion of the vessel wall occurred.

Adult↗
PubMed2004

Differential localization of decidual stathmin during pregnancy in rats.

The present study was undertaken to determine the precise localization of stathmin, a protein associated with microtubule dynamics, during decidualization in rat uterus and to compare it with that of cyclin D3. Immunohistochemical analysis revealed that stathmin is exclusively localized in decidual cells, especially in the primary decidual zone surrounding the embryo, on days 7 and 9 of pregnancy. The intensity of staining was much higher on day 9 than day 7. On day 14, when the endometrial stromal cells had completely differentiated into decidual cells, the staining of decidual cells was faint. Cyclin D3 was expressed in decidual cells of the secondary but not the primary decidual zone on days 7 and 9. On day 14, cyclin D3 levels were low in decidua. Proliferating cell nuclear antigen (PCNA) was broadly detected in the uterus on days 7 and 9, and in the placenta and fetus on day 14. In an artificial decidualization model, cyclin D3 expression was stimulated as deciduoma was formed after an artificial stimulus. Stathmin mRNA levels also increased within 24 h and peaked at 48 h. The specific spatio-temporal uterine expression of stathmin and cyclin D3 suggest that they have a specific role in decidualization in rats.

Animals↗
PubMed2004

Prognostic significance of hepatocyte growth factor and c-MET expression in patients with diffuse large B-cell lymphoma.

The expression and prognostic significance of hepatocyte growth factor (HGF) and its receptor c-MET (MET proto-oncogene) was analysed in 96 cases of diffuse large B-cell lymphoma (DLBCL). Tissue sections were immunohistochemically stained for HGF and c-Met. The prognosis of HGF-positive and c-Met-positive cases was significantly worse than negative cases (HGF: P = 0.0036; c-Met: P = 0.0002). In addition, in the low-risk international prognostic index group, HGF-negative and c-Met-negative cases had a significantly better prognosis than positive cases (HGF: P = 0.0009; c-Met: P < 0.0001). Our results suggest that HGF/c-MET is a useful clinical marker of prognosis for patients with DLBCL.

Adolescent↗
PubMed2004

A case of secondary diabetes mellitus with acromegaly improved by pioglitazone.

AIM: The acromegaly patient was diagnosed with Type 2 diabetes mellitus. His HbA1c was 10.6% and fasting blood glucose (FBG) 15.3 mmol/l. We prescribed glibenclamide (10 mg/day), but his HbA1c and FBG remained high. At this stage, treatment with short-acting insulin was instigated at a dose of 20 U/day. However, the patient's blood glucose level remained unsatisfactory. We tried using pioglitazone. METHOD: Pioglitazone was prescribed at 30 mg/day in combination with the insulin. RESULTS: The FBG and HbA1c value decreased to 7.2 mmol/l and 7.3%, respectively, within 2 months and insulin was discontinued. Pioglitazone alone was able to control the FBG level. CONCLUSIONS: Pioglitazone treatment might be considered as a choice for similar cases of diabetes secondary to acromegaly.

Acromegaly↗
PubMed2004

Deformation of adhering elastic tubes.

Deformation of an elastic tube adhering onto a substrate due to van der Waals attractive force is investigated by means of numerical minimization and scaling theory. The onset of the deformation is determined by the critical value of Cb/Epsilon N2, where Cb is the bending constant, epsilon is the depth of the van der Waals potential, and N is the size of the tube. For a significantly deformed tube, we found a scaling behavior of the bending energy, which is explained within the shell theory.

Anisotropy↗
PubMed2004

Biting suppresses stress-induced expression of corticotropin-releasing factor (CRF) in the rat hypothalamus.

Corticotropin-releasing factor (CRF) expressed in the hypothalamus plays an important role in mediating behavioral responses to stressors. Restraining the body of an animal has been shown to activate and induce an enhanced expression of CRF in paraventricular neurons of the rat hypothalamus. Since aggressive biting behavior is known to suppress stress-induced noradrenaline secretion in the central nervous system and the formation of gastric ulcers, we investigated the effect of biting on restraint-induced CRF expression in the rat hypothalamus. The number of CRF-expressing neurons in the paraventricular nucleus increased significantly after short time restraint (30 or 60 min) followed by a 180-minute post-restraint period. Biting of a wooden stick during the restraint stress significantly suppressed the restraint-induced enhancement of CRF expression in the paraventricular nucleus. These observations suggest a possible anti-stress effect of biting and an important role of para-functional masticatory activity in coping with stressful events.

Adaptation, Psychological↗
PubMed2004

Vascular endothelial growth factor increases messenger RNAs encoding cyclooxygenase-II and membrane-associated prostaglandin E synthase in rat luteal cells.

Vascular endothelial growth factor (VEGF) is known to be necessary for the vascularization of the developing corpus luteum. Our recent data suggested that cyclooxygenase-II (COX-II) may play a role in the formation of vascular plexuses in developing corpora lutea of the rat. Here we examined the relationship between VEGF and the expression of prostaglandin (PG)- metabolizing enzymes in rat ovarian luteal cells. VEGF treatment caused a dose-dependent increase in the expression of COX-II and membrane-associated PGE synthase (mPGES) mRNA in cultured rat luteal cells. However, pretreatment of the luteal cells with a selective COX-II inhibitor, NS-398, abolished the VEGF-enhanced mPGES mRNA expression. VEGF also increased PGE2 secretion. Conversely, PGE2 dose-dependently stimulated VEGF mRNA expression. Furthermore, VEGF induced VEGF mRNA expression, but this effect was abolished by NS-398 pretreatment. These findings suggest that VEGF enhances PGE2 production by stimulating COX-II and mPGES expression in rat corpus luteum and that the effect of VEGF on luteal cells may be partially mediated by this stimulation of PGE2 production.

Animals↗
PubMed2004

Effects of high pressure on the solubility and growth kinetics of monoclinic lysozyme crystals.

Average growth rates of the (0 1 0) and (0 1 0) faces (R<0 1 0>) of monoclinic lysozyme crystals were measured in situ under 0.1 and 100 MPa. From the dependence of the growth rates on the lysozyme concentration, we determined the solubility of the crystal as a function of temperature at 0.1 and 100 MPa. The solubility increased with an increase in pressure. From the comparison between the growth rates under 0.1 and 100 MPa at the same supersaturation level, we found that the growth rates of the monoclinic lysozyme crystals kinetically increase with an increase in pressure. Supersaturation dependencies of the growth rates under 0.1 and 100 MPa were well fitted with a two-dimensional (2D) nucleation growth model of a birth-and-spread type. The fitting results suggest that the increase in the growth rates with pressure can be explained by the decrease in the average ledge surface energy of 2D island, the average distance between the kinks on a step and the activation energies in the incorporation processes of solute molecules.

Animals↗
PubMed2003

Influence of whole-body pitch tilt and kinesthetic cues on the perceived gravity-referenced eye level.

We investigated the effects of whole body tilt and lifting the arm against gravity on perceptual estimates of the Gravity-Referenced Eye Level (GREL), which corresponds to the subjective earth-referenced horizon. The results showed that the perceived GREL was influenced by body tilt, that is, lowered with forward tilt and elevated with backward tilt of the body. GREL estimates obtained by arm movements without vision were more biased by whole-body tilt than purely visual estimates. Strikingly, visual GREL estimates became more dependent on whole-body tilt when the indication of level was obtained by arm lifting. These findings indicate that active motor involvement and/or the addition of kinesthetic information increases the body tilt-induced bias when making GREL judgements. The introduction of motor/kinaesthetic cues may induce a switch from a semi-geocentric to a more egocentric frame of reference. This result challenges the assumption that combining non-conflicting multiple sensory inputs and/or using intermodal information provided during action should improve perceptual performance.

Adult↗
PubMed2003

Accidentally induced periodontitis in primary dentition: longitudinal examinations of periodontal bacteria and clinical conditions.

Periodontitis is very rare in the primary dentition although it can be accidentally induced in young children. The purpose of this study was to describe a case of periodontitis in a 4-year-old child, which was accidentally induced by insertion of small plastic tubes into the dental cervix of the primary incisors during play, and to discuss the clinical, radiographic, and microbiological findings. Removal of the plastic tubes resulted in resolution of the periodontal condition. Prevotella nigrescens and Campylobacter rectus were detected in subgingival plaque samples from the affected teeth at every examination, whereas Porphyromonas gingivalis, Treponema denticola, Prevotella intermedia, and Bacteroides forsythus were never found during the two-year observation period. The clinical and microbiological results suggest that the type of periodontitis caused by such an incidence is not progressive, unlike other periodontal diseases such as prepubertal and juvenile periodontitis.

Accidents↗