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Biomedical subjects

T Tamamura

Publications and source records attributed to T Tamamura.

At least 19 recordsLinked to original sources
PubMed2004

Lasing action due to the two-dimensional quasiperiodicity of photonic quasicrystals with a Penrose lattice.

We have fabricated photonic quasicrystal lasers with a Penrose lattice that does not possess translational symmetry but has long-range order, and observed coherent lasing action due to the optical feedback from quasiperiodicity, exhibiting a variety of 10-fold-symmetric lasing spot patterns. The lattice constant dependence of lasing frequencies and spot patterns show complicated features very different from photonic crystal/random lasers, and we have quantitatively explained them by considering their reciprocal lattice. Unique diversity of their reciprocal lattice opens up new possibilities for the form of lasers.

Journal Article↗
PubMed2000

CD14-dependent and independent pathways in lipopolysaccharide-induced activation of a murine B-cell line, CH12. LX.

Using a lipopolysaccharide (LPS)-responsive murine B-cell line, CH12. LX, we assessed the possible role of CD14 in LPS-induced activation of B cells. Flow cytometric analysis indicated that CH12.LX cells expressed the CD14 molecule with a lower intensity than did the macrophage cell line J774.1. A reverse transcription-polymerase chain reaction and Northern blot analysis revealed low, but significant, levels of CD14 mRNA in CH12.LX cells, whose cDNA was identical to that of the mouse macrophage CD14 gene. After stimulation with LPS, CH12.LX cells proliferated, accompanied by up-regulations of CD14, transforming growth factor (TGF)-beta and interleukin (IL)-6 mRNA, and increased IgM and IgA secretion. In the absence of serum or with the addition of anti-CD14 monoclonal antibodies, however, LPS-stimulation induced neither the up-regulation of CD14 and TGF-beta mRNA nor an increase in IgA secretion. These findings indicate that CD14 expression is not restricted to myeloid cells, but is involved in some cellular activation events of murine B cells elicited by LPS. Furthermore, a CD14-independent pathway may also exist in the LPS-induced activation of B cells that leads to proliferation, IL-6 production and the enhancement of IgM (but not IgA) secretion.

Animals↗
PubMed1999

Comparative studies on in vitro activities of kasugamycin and clinically-used aminoglycoside antibiotics.

Kasugamycin, a unique aminoglycoside antibiotic, has been used for many years solely for crop protections. In general, aminoglycoside antibiotics possess broad and strong inhibitory activity against both Gram-positive and -negative bacteria, however, kasugamycin merely exhibits limited activity against phytopathogenic microbes such as Pyricularia oryzae and certain strains of pseudomonads. Recently, in human and animal chemotherapy, it has been seriously concerned about the emergence of multiply resistant bacteria by consumption of a large amount of antibiotics not only for therapy but also for growth-promotion of farm animals. It was believed that kasugamycin, the agricultural antibiotic, does not undergo any cross-resistance with other clinically important aminoglycoside antibiotics because of its weak or almost no activity against common pathogenic microbes except for some phytopathogenic fungi and pseudomonads. However, no confirmative study on this fact has been published so far. In this study, we compared activity of kasugamycin with those of twelve clinically used aminoglycoside antibiotics against susceptible standard strains and well-characterized aminoglycoside-resistant strains as well as clinically isolated strains, in order to show the least potential of kasugamycin to create cross-resistant human pathogens against clinically important aminoglycoside antibiotics.

Aminoglycosides↗
PubMed1993

AB5046A and B, novel chlorosis-inducing substances from Nodulisporium sp.

Novel chlorosis-inducing substances, AB5046A and B, were isolated from the culture broth of a fungal strain. The producing organism, designated AB5046, was identified as a member of Nodulisporium. AB5046A and B were purified by extraction with EtOAc and silica gel chromatography. The structure of AB5046A and B were determined to be 2-butyryl-3,5-dihydroxy-cyclohex-2-ene-1-one and 2-acetyl-3,5-dihydroxy-cyclohex-2-ene-1-one, respectively, by spectroscopic analyses. AB5046A and B induced chlorosis against Japanese barnyard millet in vitro. The chlorosis activity of these compounds was stronger against monocotyledons than dicotyledons.

Animals↗
PubMed1992

Progression of Takayasu's aortitis in a young Japanese woman: serial angiographic study.

Progression of Takayasu's aortitis was observed by serial angiography over 2 years. Acute aortic regurgitation due to marked dilatation of the proximal ascending aorta was followed by aneurysmal dilatation of the distal ascending aorta. Aneurysmal dilatation of the carotid arteries then developed, with subsequent obstruction of both the bilateral vessels by thrombosis.

Adult↗
PubMed1992

Transient increase in wall thickness of the left ventricular apex after stunned myocardium: a case report.

A case of transiently increased wall thickness in the left ventricular apex after stunned myocardium due to severe attack of vasospastic angina is described. "Ace of spades" configuration, documented by left ventriculogram and increased apical wall thickness of the left ventricle, as revealed by two-dimensional echocardiograms returned to normal in 2 months. This transiently increased left ventricular mass may have been due to myocardial edema, which is occasionally seen in the recovery course of active myocarditis.

Angina Pectoris↗
PubMed1992

AB3217-A, a novel anti-mite substance produced by a strain of Streptomyces platensis.

AB3217-A, a novel anti-mite substance, was isolated from the fermentation broth of a streptomycete strain. The strain was isolated from a soil collected at Kita-azumi, Nagano Prefecture, Japan, and identified as Streptomyces platensis AB3217. AB3217-A was purified by Amberlite IR120B, Diaion HP-20 and CM-Sephadex C-25 column chromatographies. The molecular formula was determined as C17H23NO7 by elemental analysis, MS and 13C NMR spectroscopy. The structure of AB3217-A was determined to be (1R,3S,4S,7R,8R,11R,12S,13R)-4,12,13-trihydroxy-8-(4-methoxy phenyl)-6-aza-2,9,14-trioxatricyclo-[9.2.1.0(3,7)]tetradecane by spectroscopic analysis and X-ray crystallographic analysis. The molecule of AB3217-A has unique structure that deacetylanisomycin and beta-D-xylofuranose linked through glycosidic bond and ether bond resulting in the formation of nine-membered ring. AB3217-A showed marked activity against the two spotted spider mite, Tetranychus urticae.

Animals↗
PubMed1992

[Usefulness of magnetic resonance imaging (MRI) in evaluation of left ventricular apical aneurysm].

Twenty three consecutive cases of left ventricular aneurysm due to antero-septal myocardial infarction in normal sinus rhythm were studied to decide whether or not magnetic resonance imaging (MRI) can evaluate aneurysm of the left ventricular apex. The apex, as well as the base, of the left ventricle was clearly imaged in 21 out of 23 cases. Poor images were obtained in two cases who showed frequent premature ventricular beats during this procedure. Two-dimensional echocardiography has weak points when visualizing left ventricular apex because, for one thing, the sector angle is maximally 90 degrees, and for another, the cardiac apex is too near the probe for observation of the characteristic of the left ventricular apical wall. However, MRI can make up for the above weak points and can provide supportive information by visualizing the entire left ventricular apex.

Adult↗
PubMed1991

Transient segmental asynergy of the left ventricle of patients with various clinical manifestations possibly unrelated to the coronary artery disease.

Eight cases of transient reversible segmental asynergy of the left ventricle thought not to be related to coronary artery lesions are reported. Three cases were associated with inflammatory reactions of unknown origin, and one each with lactic acidosis, abdominal surgery, hypoglycemia, tetanus and pneumonia. None of the patients had symptoms suggestive of ischemic heart disease before or after these episodes. Electrocardiograms before these episodes were all normal. Two-dimensional echocardiography was performed to evaluate abnormal electrocardiograms. Coronary angiography was performed in 4 of 8 cases and was normal in all 4 cases; 2 done as emergencies and 2 non-emergencies. Two ergonovine tests were negative. Left ventricular wall motion abnormalities, present mainly at the apex of the left ventricle, returned to normal in 1 to 4 weeks. Giant negative T waves in the chest leads during this recovery period were characteristic electrocardiographic features and normalized in 6 weeks on average. We believe that these episodes were not related to ischemia due to coronary artery disease, but to some metabolic humoral factors. An excellent prognosis can be expected if these abnormal metabolic circumstances can be resolved.

Aged↗
PubMed1991

Native valve infective endocarditis in adults--analysis of 32 consecutive cases over a ten-year period from 1980 to 1989.

Thirty-two patients with native valve infective endocarditis who presented over a 10-year period at our hospital were analyzed retrospectively. The presenting symptom was a persistent fever in 22 patients. In 30 patients, the New York Heart Association functional class was less than II before the development of endocarditis. Blood cultures were positive on all occasions in 24 out of 29 culture-positive patients. All of the viridans streptococci, accounting for 79% of the isolated pathogens, were highly susceptible to ampicillin. Treatment consisted of a 6 week course of antibiotics, usually ampicillin, at a dose of 12 grams/day. In 9 cases, we had to change or stop the antibiotics because of severe side effects. The longer the period before making a diagnosis, the more severe were the symptoms of congestive heart failure and the more frequent was the incidence of cerebral hemorrhage. To initiate treatment as early as possible, in order to minimize valve destruction and to reduce the risk of cerebral hemorrhage, serial blood cultures are recommended in patients with valvular heart disease or congenital heart disease and a persistent fever, with minimal cardiac symptoms.

Adult↗
PubMed1991

Progressive restrictive cardiomyopathy--a case report.

We present a case of restrictive cardiomyopathy which progressed over a 10 month period. A 69-year-old female was admitted because of acute inferior myocardial infarction; hemodynamically, she was in Forrester subset I. Cardiac catheterization performed 4 weeks post-infarction showed markedly increased left ventricular end-diastolic and pulmonary wedge pressures. Left ventricular ejection fraction was 66% with postero-basal akinesis and minimal mitral regurgitation. The right coronary artery was completely occluded with good collateral circulation from the intact left coronary artery. Doppler echocardiography 4 weeks post-infarction showed pseudo-normalization of the A/E ratio of peak mitral flow velocity in atrial systole (A) to peak mitral flow velocity in early diastole (E). Preload reduction by nitroglycerin increased the A wave. Ten months post-infarction, the patient was re-admitted due to congestive heart failure. The A/E ratio was unchanged, however the A wave no longer increased after the same dose of nitroglycerin. We have hypothesized that dehydration and/or the vigorous use of a nitrate, in the acute phase of myocardial infarction, masked an underlying restrictive cardiomyopathy which progressed in the 10 months post-infarction.

Blood Flow Velocity↗
PubMed1991

A case of unusual longevity of tetralogy of Fallot confirmed by cardiac catheterization.

We describe a 61-year-old woman with tetralogy of Fallot and dextrocardia with complete situs inversus. The functional status of this patient was New York Heart Association (NYHA) class II and the systemic blood pressure was 100/54 mmHg. The hematocrit was 54.4% and the arterial partial pressure of oxygen was 53 mmHg. On cardiac catheterization, both pulmonary valvular and infundibular stenoses were of equal severity and the aorta and main pulmonary artery were of equal size. We think that this patient has survived to this unusual age for tetralogy of Fallot because of unusually low systemic pressure and a proper balance between the ventricular septal defect and the pulmonary stenosis.

Cardiac Catheterization↗
PubMed1991

[Two cases of atrial septal defect diagnosed by two-dimensional Doppler echocardiography: comparison with other methods for detecting atrial septal defect].

We describe two cases of atrial septal defect(ASD) diagnosed by chance with two-dimensional Doppler echocardiography(2DD) which was carried out for another purpose. There were no findings characteristic of ASD such as systolic murmurs in the pulmonary area, incomplete right bundle branch block pattern on electrocardiograms, increased hilar shadow on chest films or increased right ventricular chamber diameter in two-dimensional echocardiography. However, the 2DD showed blood flow crossing through the atrial septum. Cardiac catheterization confirmed the presence of a small ASD. ASD diagnosed by 2DD alone without other classical characteristic signs of ASD indicates that the ASD is small and clinically insignificant as it is with Doppler valvular heart disease.

Adult↗