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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 181 records · Page 10Linked to original sources
PubMed1999

[Hypertensive heart disease with left ventricular diastolic dysfunction demonstrating restrictive hemodynamics: a case report].

A 47-year-old man with hypertensive heart disease and left heart failure due to left ventricular diastolic dysfunction was admitted to our hospital because of emergent hypertension. Chest radiography on admission showed slight cardiomegaly and mild pulmonary congestion with right pleural effusion Echocardiography showed concentric hypertrophy and normal contraction of the left ventricular wall Pulsed Doppler left ventricular inflow velocity wave and pulmonary venous flow velocity wave disclosed restrictive filling patterns. After Ca antagonist, nitrate, and diuretics were administered, blood pressure was normalized, and left ventricular inflow velocity wave showed the relaxation abnormality pattern and pulmonary venous flow velocity wave showed the normal pattern. Radioiodinated iodine-123 metaiodobenzyl guanidine (123I-MIBG) imaging in the state of normalized blood pressure showed decreased heart to mediastinum ratio and increased washout rate. Left heart catheterization and angiography revealed normal end-diastolic pressure and coronary arteries, but coronary flow reserve evaluated with Doppler flow wire and intracoronary adenosine triphosphate administration was impaired: Plasma level of atrial and brain natriuretic peptides, which were markedly elevated on admission, decreased with the improvement of heart failure. Doppler flow velocity patterns, plasma levels of atrial natriuretic peptide and brain natriuretic peptide, cardiac sympathetic nerve activity, and coronary flow reserve might be useful for evaluating the severity of left ventricular diastolic dysfunction in patients with hypertensive heart disease.

Atrial Natriuretic Factor↗
PubMed1999

[A case of a traumatic anterior cerebral artery aneurysm following the penetration of the skull base by an iron rod].

A 61-year-old male fell from a position 1 m high when building a house. An iron rod, which protruded upward from a solid base in cement, penetrated this patient's neck 15 cm to the head and was successfully extracted by himself. On admission, he complained of headache and vomiting. General examination disclosed nasal bleeding, intraoral bleeding, and L figured skin laceration in the left side of his neck at the level of the thyroid cartilage. Mild disorientation (JCS2) was noted. Otolaryngological examination disclosed hyperemia on the left side of the vocal cord as well as at the dome of the superior pharynx. Plain skull film disclosed pneumocephalus and that a piece of bone fragment of the planum sphenoidale had penetrated the brain. CT demonstrated air in the subarachnoid space, ventricular hemorrhage, intracerebral hematoma in the right frontal lobe, and subarachnoid hemorrhage in the anterior interhemispheric fissure. CAG detected neither cerebral vascular abnormalities nor cerebral aneurysm. While staying in our department, he developed mild fever and CSF rhinorrhea. The diagnosis of bacterial meningitis was made from the CSF finding and was well controlled with conservative therapy. CSF rhinorrhea stopped spontaneously with conservative treatment. Sagittal MRI continuously demonstrated contusional hematoma in the base of the right frontal lobe just above the fractured planum sphenoidale and genu of the corpus callosum following the course of the intracranially invading iron rod. The right CAG on Day 10 demonstrated vasospasm on the A1 and a 1 cm sized saccular cerebral aneurysm at the proximal right fronto-polar artery. CAG on Day 17 again showed the persistent presence of the aneurysm. For the purpose of preventing delayed rupture of the aneurysm, radical surgical treatment was planned. Microsurgical dissection disclosed that the aneurysm was located just behind the elevated fracture of the planum sphenoidale. Severe arachnoid adhesion was noted around the aneurysm. The aneurysm was successfully clipped with preservation of the parent artery without inducing new neurological deficits. From the general, otolaryngological, neuroradiological, and operative findings, this aneurysm was diagnosed as a traumatic cerebral artery aneurysm following the penetration of the skull base by the iron rod. The CAG performed at 8 months postoperatively demonstrated the patency of the parent artery and that there was no recurrence of the aneurysm. An unusual case of a traumatic cerebral artery aneurysm following the penetration of the skull base by an iron rod was thus reported.

Accidents, Occupational↗
PubMed1999

[Factors relate to participation in medical checkups in a rural community an analysis including social network scores].

Since 1969, community-based stroke prevention programs have been conducted in N town, Kochi prefecture. To clarify factors related to participation in medical checkups including social networks, a cross-sectional questionnaire survey was performed on 6,704 residents aged 40 and over in N town in 1996. 1. Location of the workplace, types of medical insurance and interest in health were significantly associated with participation in medical checkups. 2. Participation in medical examinations provided at the workplace was significantly, inversely related with participation rates in community checkups in the group aged 40 to 59 years. 3. Low independence level in daily activities was inversely associated with participation rates for medical checkups in groups aged 60 years and older. 4. Visiting medical facilities was inversely associated with the participation rate for medical checkups in female groups. 5. The group with the highest social networks score (5 points) had the highest participation rate for medical checkups. After adjusting for other participation related factors, social networks scores had a significantly positive association with the participation rate for medical checkups provided by the Health Services for the Elderly Act.

Adult↗
PubMed1999

Nurses' perspectives concerning do-not-resuscitate (DNR) orders.

The purpose of this study was to investigate the views of the nursing staff concerning do-not-resuscitate (DNR) orders at the Tokai University Hospital where a controversial incident occurred several years ago. A 'Questionnaire on DNR Orders' was circulated and the anonymous answers were collected two weeks later. The questionnaire was returned by 706 of 780 (90.5%) nurses from every ward/specialty, which revealed that 87% of the nurses felt that DNRs were occasionally necessary, with more than 40% of the nurses answering that they took part in DNR. Further, 36% of the nurses stated that patient consent was indispensable, and 64% thought that the patient's family and physician could decide DNR in the event the patient was physically unable to give consent. Moreover, 66% of the nurses expected the establishment of a DNR order sheet to be formulated as a matter of hospital policy; only 5% of the nurses thought that such an order sheet would not be necessary. Comparing these results with a previous study polling physicians at the Tokai University Hospital, nurses are more likely than physicians to think that patient consent is indispensable, and want the establishment of a standardized DNR order sheet as hospital policy. There is, in fact, a "tacit understanding" between physicians and patients' families in medical practice in Japan. However, DNR is definitely a medical decision. Therefore it should be clearly stated in a standardized format, although such a procedure presently seems unlikely, in view of the Japanese traditional value system.

Adult↗
PubMed1999

[Antiangiogenic and antitumor effect of BPHA, an orally-active matrix metalloproteinase inhibitor, in in vivo murine and human tumor model].

We examined the antiangiogenic and antitumor efficacy of a newly-developed matrix metalloproteinase (MMP) inhibitor, BPHA (N-biphenyl sulfonyl-phenylalanine hydroxiamic acid). BPHA potently inhibits MMP-2, 9 and 14 but not MMP-1, 3 or 7. In contrast, (-)BPHA, an enantiomer of BPHA, was inactive against all MMP tested. Daily oral administration of BPHA in mice resulted in potent inhibition of tumor-induced angiogenesis, primary tumor growth and liver metastasis, whereas (-)BPHA did not. These results demonstrate that selective MMP inhibition is correlated with antiangiogenic and antitumor efficacy and that the selective MMP inhibitor BPHA has therapeutic potential without hematotoxic effect or loss of body weight.

Animals↗
PubMed1998

Protective effects of vasoactive intestinal peptide against delayed glutamate neurotoxicity in cultured retina.

The effects of vasoactive intestinal peptide (VIP) on glutamate-induced delayed death were examined using the primary cultures of rat retinal neurons. Effects of VIP on glutamate-induced neurotoxicity were evaluated by double staining with fluorescein diacetate and propidium iodide. Glutamate (1 mM) was applied to the culture for 10 min in the presence and absence of VIP, and visible cells enumerated 24 h after culture in normal medium. Effects of VIP on increase in the intracellular Ca2+ concentration and currents induced by glutamate in retinal neurons were investigated using the Ca2+ image analyzing system with fura-2 and whole-cell patch-clamp recording, respectively. The cAMP contents in retinal cultures were measured by radioimmunoassay. VIP (10 nM-1 microM) dose-dependently protected against glutamate-induced neurotoxicity in cultured retinal neurons. Protection by VIP (100 nM) against glutamate (1 mM)-induced neurotoxicity was antagonized by VIP6-28 (1 microM), a VIP antagonist, and H-89 (100 nM and 1 microM), a protein kinase A inhibitor. However, VIP had no effect on glutamate-induced inward currents nor glutamate-induced increase in the intracellular Ca2+ concentration. A 10-min exposure of VIP (100 nM) with glutamate (1 mM) resulted in an increase in the cAMP level to 446+/-58 from 22+/-1 pmol/mg protein. These findings suggest that VIP protects against the glutamate-induced neurotoxicity in retinal cultures by elevating the cAMP level via VIP receptors and thereby activating protein kinase A.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Differential activity of a variant form of the human Id-1 protein generated by alternative splicing.

Members of the Id family of helix-loop-helix proteins are ubiquitously expressed and dimerize with members of the class A and class B basic helix-loop-helix proteins. Due to the absence of a basic region, Id proteins act as dominant-negative antagonists of basic helix-loop-helix transcription factors, which regulate cell growth and differentiation in diverse cell types. Recent findings suggest that the functions of Id proteins are well regulated at both the transcriptional level and the post-transcriptional level. We show here that the alternative splicing variant of human Id-1 protein possesses a different binding specificity for basic helix-loop-helix transcription factors and is expressed in a cell cycle-dependent manner. Therefore, alternative splicing of Id-1 could provide a post-transcriptional mechanism to regulate Id-1 function.

Alternative Splicing↗
PubMed1998

Expression of the mphB gene for macrolide 2'-phosphotransferase II from Escherichia coli in Staphylococcus aureus.

The genes mphA and mphB encode macrolide 2'-phosphotransferases I and II, respectively, and they confer resistance to macrolide antibiotics in Escherichia coli. To study the expression of these genes in Gram-positive bacteria, we constructed recombinant plasmids that consisted of an mph gene and the pUB110 vector in Bacillus subtilis. When these plasmids were introduced into Staphylococcus aureus, the mphB gene was active and macrolide 2'-phosphotransferase II was produced. The gene endowed S. aureus with high-level resistance to spiramycin, a macrolide antibiotic with a 16-membered ring. Moreover, transcription of the mphB gene in S. aureus began at the promoter that was active in E. coli.

Escherichia coli↗
PubMed1998

Highly selective and orally active inhibitors of type IV collagenase (MMP-9 and MMP-2): N-sulfonylamino acid derivatives.

Various N-sulfonylamino acid derivatives were synthesized and evaluated for their in vitro and in vivo activities to inhibit type IV collagenase (MMP-9 and MMP-2). When the amino acid residue and the sulfonamide moiety were modified, their inhibitory activities were greatly affected by the structure of the sulfonamide moiety. A series of aryl sulfonamide derivatives containing biaryl, tetrazole, amide, and triple bond were found to be potent and highly selective inhibitors of MMP-9 and MMP-2. In addition, these compounds were orally active in animal models of tumor growth and metastasis. These results revealed the potential of the N-sulfonylamino acid derivatives as a new type of candidate drug for the treatment of cancer.

Administration, Oral↗
PubMed1998

Bisphenol-A induces cellular transformation, aneuploidy and DNA adduct formation in cultured Syrian hamster embryo cells.

Bisphenol-A (BP-A) is a major component of epoxy, polycarbonate and other resins. For an assessment of in vitro carcinogenicity and related activity of BP-A, the abilities of this compound to induce cellular transformation and genetic effects were examined simultaneously using the Syrian hamster embryo (SHE) cell model. Cellular growth was reduced by continuous treatment with BP-A at doses > or = 100 microM. However, colony-forming efficiencies were not decreased significantly following treatment with up to 200 microM BP-A for 48 hr. Morphological transformation of SHE cells was induced by treatment of cells with BP-A at 50 to 200 microM for 48 hr. BP-A exhibited transforming activity at doses > or = 50 microM but was less active than the benzo[alpha]pyrene used as a positive control. Over the dose range that resulted in cellular transformation, treatment of SHE cells with BP-A failed to induce gene mutations at the Na+/K+ ATPase locus or the hprt locus. No statistically significant numbers of chromosomal aberrations were detected in SHE cells treated with BP-A. However, treatment of cells with BP-A induced numerical chromosomal changes in the near diploid range at doses that induced cellular transformation. 32P-Postlabeling analysis revealed that exposure of cells to BP-A also elicited DNA adduct formation in a dose-dependent fashion. Our results indicate that BP-A has cell-transforming and genotoxic activities in cultured mammalian cells and potential carcinogenic activity.

Aneuploidy↗
PubMed1998

Mode of antibacterial action of retrochalcones from Glycyrrhiza inflata.

Licochalcone A-D and echinatin, retrochalcones isolated from the roots of Glycyrrhiza inflata, showed antimicrobial activity. Among them, licochalcone A and C had potent activity against some Gram-positive bacteria. These retrochalcones inhibited oxygen consumption in susceptible bacterial cells. The oxidation of NADH in bacterial membrane preparations was also inhibited by them. NADH-cytochrome c reductase was inhibited by licochalcones, while cytochrome c oxidase was not. NADH-CoQ reductase and NADH-FMN oxidoreductase were not inhibited. The site of respiratory inhibition of licochalcones was thought to be between CoQ and cytochrome c in the bacterial respiratory electron transport chain.

Anti-Bacterial Agents↗
PubMed1998

Antioxidative and superoxide scavenging activities of retrochalcones in Glycyrrhiza inflata.

Licochalcone A, B, C, D and echinatin, retrochalcones isolated from the roots of Glycyrrhiza inflata (licorice), along with an ordinary chalcone isoliquiritigenin, were assessed for their inhibitory activities on lipid peroxidation in various systems and radical scavenging activity. Among those tested, licochalcones B and D strongly inhibited superoxide anion production in the xanthine/xanthine oxidase system. These two compounds also showed potent scavenging activity on DPPH radical. Microsomal lipid peroxidation induced by Fe(III)-ADP/NAPDH was inhibited almost completely by 3 micrograms/ml of licochalcones B and D. Mitochondrial lipid peroxidation induced by Fe(III)-ADP/NADH was more sensitive to these retrochalcones; almost complete inhibition was observed at 10 micrograms/ml of all retrochalcones tested. Licochalcones B and D scavenged superoxide anion in microsome. Furthermore, these retrochalcones protected red cells against oxidative hemolysis. These phenolic compounds were shown to be effective to protect biological systems against various oxidative stresses.

Animals↗
PubMed1998

Development of flat adenoma and superficial rectal cancer after pelvic radiation.

Little is known about the early development of rectal cancer in patients with radiation-induced colitis. We describe two patients with a history of radiation colitis who developed rectal cancer. The macroscopic appearance of these lesions suggested that they arose de novo, but the histologic findings were more consistent with progression along the adenoma-to-carcinoma sequence, a hybrid of de novo lesion and adenoma. Early rectal cancer associated with chronic inflammation should be considered if a nonpolypoid adenomatous lesion is detected in a patient who has received pelvic radiation.

Adenocarcinoma, Mucinous↗
PubMed1998

Optimized acquisition time and image sampling for dynamic SPECT of Tl-201.

With the recent development in scatter and attenuation correction algorithms, dynamic single photon emission computerized tomography (SPECT) can potentially yield physiological parameters, with tracers exhibiting suitable kinetics such as thallium-201 (Tl-201). A systematic way is proposed to investigate the minimum data acquisition times and sampling requirements for estimating physiological parameters with quantitative dynamic SPECT. Two different sampling schemes were investigated with Monte Carlo simulations: 1) Continuous data collection for total study duration ranging from 30-240 min. 2) Continuous data collection for first 10-45 min followed by a delayed study at approximately 3 h. Tissue time activity curves with realistic noise were generated from a mean plasma time activity curve and rate constants (K1 - k4) derived from Tl-201 kinetic studies in 16 dogs. Full dynamic sampling schedules (DynSS) were compared to optimum sampling schedules (OSS). We found that OSS can reliably estimate the blood flow related K1 and Vd comparable to DynSS. A 30-min continuous collection was sufficient if only K1 was of interest. A split session schedule of a 30-min dynamic followed by a static study at 3 h allowed reliable estimation of both K1 and Vd avoiding the need for a prolonged (>60-min) continuous dynamic acquisition. The methodology developed should also be applicable to optimizing sampling schedules for other SPECT tracers.

Animals↗