Biomedical subjects

T Hamada

Publications and source records attributed to T Hamada.

At least 199 records · Page 11Linked to original sources

PubMed1998

Denture plaque--past and recent concerns.

OBJECTIVE: This paper critically reviews the history of denture plaque and identifies some concerns with the presence of Candida in the mouth. DATA SOURCES: This review covers literature sources related to Candida albicans and its relationship to denture plaque. STUDY SELECTION: The articles selected for this review are from referred journals and describe C. albicans and its relationship to oral, gastrointestinal and pleuropulmonary infections. The relationship to caries, root caries and periodontal disease is also covered. CONCLUSIONS: Denture plaque containing Candida could cause not only oral candidiasis, like oral thrush or denture-induced stomatitis, but also caries, root caries and periodontitis of abutment teeth. However, there is only limited experimental evidence or information available on the cariogenicity of Candida. The continuous swallowing or aspiration of micro-organisms from denture plaque exposes patients, particularly the immunocompromised host or medicated elderly, to the risks of unexpected infections. The term, 'denture plaque' has been used throughout the review. However, the term 'plaque on denture' should be used because the microbial flora and its pathogenicity of denture plaque resembles those of plaque formed on the tooth surface, so called dental plaque. In addition, the term 'denture related stomatitis' would be preferable to 'denture induced stomatitis', since the inflammation of (palatal) mucosa is not induced by the denture, but by wearing the denture or by plaque on the denture.

Aged↗

PubMed1998

Examination of DNA-binding activity of neuronal transcription factors by electrophoretical mobility shift assay.

Electrophoretical mobility shift assay (EMSA) is a simple, rapid, and highly sensitive technique for detection of single- or double-stranded DNA-binding proteins such as transcription factors in crude nuclear extracts (F.M. Ausubel, R. Brent, R.E. Kingston, D. D. Moore, J.G. Seidman, J.A. Smith, K. Struhl (Eds.), Current Protocols in Molecular Biology, Greene Publishing Associates and Wiley-Interscience, 1989, pp. 12.0.1-12.2.10 [1]; J. Carey, Gel Retardation. Methods Enzymol., 208 (1991) 103-117 [2]). By using this technique, it is possible to quantify the abundance, relative affinity and binding specificity of DNA-binding proteins. Since proteins which bind specifically to radiolabeled DNA probes retard the mobility of the probe during electrophoresis (it also called gel retardation assay), discrete bands correspond to the individual DNA-protein complexes. Furthermore, EMSA allows one to determine which member(s) of a certain protein family are included in the DNA-protein complex by means of specific antibodies raised against the DNA-binding protein (supershift assay).

Animals↗

PubMed1998

Merkel cell carcinoma, Bowen's disease and chronic occupational arsenic poisoning.

We diagnosed a unique case of Merkel cell carcinoma (MCC) coexisting with Bowen's disease on the sole of the foot of a 72-year-old man who had worked for about 4 years in a factory handling inorganic arsenic. He had a past history of arsenical keratosis and multiple Bowen's disease. The tumour first appeared as a reddish macule and then showed marked growth over the next month. The tumour was excised and the specimen was examined histopathologically. The tumour consisted of two components: a group of atypical cells representing Bowen's disease in the epidermis and another group of atypical cells with a trabecular pattern characteristic of MCC in the dermis. Neither group of cells showed transitional findings, and the tumour elements were divided by a clear basement membrane. The tumour cells in the dermis were positive for neurone-specific enolase, and on electron microscopy had dense core granules in the cytoplasm. Inorganic arsenic can cause various cutaneous neoplasms, but to our knowledge, this is the first report of a case of MCC associated with Bowen's disease.

Aged↗

PubMed1998

Expression of the PAX5/BSAP transcription factor in haematological tumour cells and further molecular characterization of the t(9;14)(p13;q32) translocation in B-cell non-Hodgkin's lymphoma.

The PAX5 gene encodes the BSAP (B-cell-specific activator protein) which is a key regulator of B-cell development and differentiation. A recurring translocation t(9;14)(p13;q32) in non-Hodgkin's lymphoma moves the PAX5 on 9p13 within close proximity of the immunoglobulin heavy chain gene (IGH). KIS-1 cell line was established from a patient with diffuse large cell lymphoma of B-cell type carrying t(9;14). We analysed PAX5/BSAP expression by Northern and Western blotting in a panel of haematological tumour cell lines with other chromosome abnormalities in comparison with that of KIS-1. PAX5 mRNA and BSAP expression were detected in all B-cell lines tested, and the high level in KIS-1 was confirmed. However, a diffuse large B-cell lymphoma cell line and an acute B-lymphoid/myeloid leukaemia cell line expressed the PAX5/BSAP at levels comparable with KIS-1. PAX5 transcripts were readily detectable in clinical materials with a wide variety of B-cell neoplasms by reverse transcriptase-mediated polymerase chain reaction (PCR). Thus, PAX5/BSAP activation in haematological tumour cells is not necessarily associated with t(9;14). Although binding sites for BSAP have been identified in the promoters of CD19, this study failed to find clear correlation between the level of PAX5/BSAP expression and that of CD19. In contrast to KIS-1 in which the E mu enhancer of IGH was juxtaposed to PAX5, cloning of t(9; 14) from another case by long-distance PCR revealed that the PAX5 promoter was linked to a Cgamma constant region in divergent orientation, suggesting that the mechanism of PAX5 activation through recombination with IGH varies among individual cases. Breakpoints on 9p13 of the two translocations were clustered upstream of PAX5, leaving the PAX5 coding region intact.

Base Sequence↗

PubMed1998

Comparison of the most comfortable mandibular position with the intercuspal position using cephalometric analysis.

For evaluation of the most comfortable position (MCP) in edentulous subjects, as decided by mandibular position sense, the MCP was recorded in ten edentulous subjects and compared with the intercuspal position (ICP) of normal dentate persons. It was found that the MCP was at a lower mandibular position than the ICP; the facial height was markedly reduced in the former by a front-upward rotation of the mandible centering around the condyles. Thus, it has been suggested that the occlusal vertical dimension (OVD) of the MCP in the restored dentition is less than that of the original ICP.

Age Factors↗

PubMed1998

Viscoelastic properties of tissue conditioners--influence of molecular weight of polymer powders and powder/liquid ratio and the clinical implications.

The effect of the molecular weight of polymer powders and the polymer powder/liquid ratio on the viscoelastic properties after gelation of tissue conditioners was studied by means of a stress relaxation test. The results are summarized as follows. The lower-molecular-weight polymer powders produced the larger flow after gelation especially at long times. The use of a lower powder/liquid ratio produced a greater flow after gelation at both short times and long times. The difference in the molecular weight of polymer powders and the powder/liquid ratio was found to have no influence on changes in viscoelastic properties with the passage of time. It would be possible to control the viscoelastic properties of tissue conditioners suitable for each clinical purpose by making variations in composition and structure.

Dibutyl Phthalate↗

PubMed1998

Altered membrane skeleton of red blood cells participates in cadmium-induced anemia.

Poikilocytosis of red blood cells (RBCs) was observed to be associated with anemia in rats given subcutaneous injections of cadmium (Cd). Phase-contrast light and scanning electron microscopic examinations revealed that acanthocytes appeared in the early stages of administration, and that the number of RBC fragments increased later. Ultrastructural analysis of RBC ghosts by negative staining demonstrated that the normal lattice structure of the membrane skeleton was abolished. The osmotic fragility curve of the Cd-exposed RBCs disclosed that most of the cells were less fragile than control RBCs. These data indicate that the RBC membrane skeleton is initially altered by Cd-exposure, followed by deformation of the cell, thus promoting intrasplenic hemolysis, and resulting in anemia.

Acanthocytes↗

PubMed1998

Evaluation of changes in sympathetic nerve activity and heart rate in essential hypertensive patients induced by amlodipine and nifedipine.

OBJECTIVE: To compare the effects of amlodipine and nifedipine on heart rate and parameters of sympathetic nerve activity during the acute and chronic treatment periods in order to elucidate their influence on cardiovascular outcome. DESIGN: A randomized and single-blind study. METHODS: We performed 24 h ambulatory electrocardiography and blood pressure monitoring of 45 essential hypertensive inpatients. Plasma and urinary catecholamine levels were measured during the control (pretreatment) period, on the first day (acute period) and after 4 weeks (chronic period) of administration of amlodipine and of short-acting nifedipine or its slow-releasing formulation. The low-frequency and high-frequency power spectral densities and low-frequency: high-frequency ratio were obtained by heart rate power spectral analysis. RESULTS: Blood pressure was significantly and similarly reduced by administrations of amlodipine, short-acting nifedipine and slow-releasing nifedipine during the chronic period. The total QRS count per 24 h, which remained constant during the chronic period of administration of slow-releasing nifedipine and was increased by administration of nifedipine, was decreased by 2.8% by administration of amlodipine. Administration of amlodipine decreased the plasma and urinary norepinephrine levels during the chronic period, whereas the levels were significantly increased by administration of short-acting nifedipine and not changed by administration of slow-release nifedipine. Although low-frequency: high-frequency ratio was increased significantly by administration of short-acting nifedipine and slightly by administration of slow-releasing nifedipine, administration of amlodipine reduced it during the acute and chronic periods. CONCLUSIONS: Administration of amlodipine did not induce an increase in sympathetic nerve activity in essential hypertensive patients during the chronic period, suggesting that beneficial effects on essential hypertension can be expected after its long-term administration. Administration of slow-releasing nifedipine induces milder reflex sympathetic activation than does that of short-acting nifedipine.

Adult↗

PubMed1998

Thermal injury induces thymocyte apoptosis in the rat.

BACKGROUND: The thymus plays important roles in host defense, which may be impaired after burn injury. The effects of thermal injury on thymocytes were investigated in male Wistar rats. METHODS: Changes in thymus weight and content of glutathione and corticosterone were determined after burn injury. Apoptosis of thymocytes was detected by electrophoresis of DNA, and lymphocyte subsets were characterized by flow cytometry. The effects of adrenalectomy and the glucocorticoid receptor antagonist RU486 in burned animals were also studied. RESULTS: The weight of the thymus decreased progressively after burn injury, and this effect was accompanied by increases in the corticosterone concentration in plasma and the thymus and apoptosis of CD4+CD8+ thymocytes. Administration of RU486 or adrenalectomy inhibited burn-induced thymocyte apoptosis. CONCLUSION: Thermal injury increases the corticosterone concentration in plasma and the thymus and triggers thymocyte apoptosis.

Adrenalectomy↗

PubMed1998

Characterization of transgenic tobacco with an increased alpha-linolenic acid level

Microsomal omega-3 fatty acid desaturase catalyzes the conversion of 18:2 (linoleic acid) to 18:3 (alpha-linolenic acid) in phospholipids, which are the main constituents of extrachloroplast membranes. Transgenic tobacco (Nicotiana tabacum) plants with increased 18:3 contents (designated SIIn plants) were produced through the introduction of a construct with the tobacco microsomal omega-3 fatty acid desaturase gene under the control of the highly efficient promoter containing the E12Omega sequence. 18:3 contents in the SIIn plants were increased by about 40% in roots and by about 10% in leaves compared with the control plants. With regard to growth at 15 degreesC and 25 degreesC and the ability to tolerate chilling at 1 degreesC and 5 degreesC, there were no discernible differences between the SIIn and the control plants. Freezing tolerance in leaves and roots, which was assessed by electrolyte leakage, was almost the same between the SIIn and the control plants. The fluidity of plasma membrane from the SIIn plants was almost the same as that of the control plants. These results indicate that an increase in the 18:3 level in phospholipids is not directly involved in compensation for the diminishment in growth or membrane properties observed under low temperatures.

Journal Article↗

PubMed1998

Systemic expression of a newly recognized protein, LECT2, in the human body.

LECT2 (leukocyte cell-derived chemotaxin 2) is a new, recently isolated protein shown to be synthesized by hepatocytes. All hepatocytes show diffuse immunostaining for LECT2 within the cytoplasm. In the present study an attempt was made to investigate the expression of LECT2 in normal and diseased human organs and tissues, other than the liver, using indirect immunoperoxidase staining. LECT2 was found to be generally expressed in vascular, endothelial and smooth muscle cells, adipocytes, cerebral nerve cells, apical squamous epithelia, parathyroid cells, sweat and sebaceous glandular epithelia, Hassall bodies and some mononuclear cells in immunohematopoietic tissue, although some of these cells and tissues were occasionally unstained in diseased conditions. Alternatively, this protein was generally negative, although it was occasionally positively stained in osteoblasts, chondrocytes, cardiac and skeletal muscle cells, smooth muscle cells of the gastrointestinal tract, and the epithelial cells of some tissues. LECT2 seems to be related to the cell cycle or repair process following damage to a variety of cells.

Adolescent↗

PubMed1998

Frequency- and time-domain analysis of P wave in patients with paroxysmal atrial fibrillation.

We investigated the usefulness of the time- and frequency-domain analysis of the P wave triggered signal-averaged ECG (P-SAECG) for detecting patients with paroxysmal atrial fibrillation (Paf). In previous studies, the usefulness of the time domain of the P-SAECG to detect patients with Paf was described but that of the frequency domain is unknown. We analyzed the P-SAECG in the time and frequency domain in 23 patients with Paf and 19 controls. The 32-unipolar chest lead ECGs and the standard bipolar limb lead ECGs were obtained. The time-domain analysis showed that the filtered P duration (fPd) was significantly longer (P < 0.01) in patients with Paf than controls: the predictive accuracy of Paf with fPd > 120 ms was 69%. The frequency domain analysis showed that the area ratio of power spectrum area of 0-20 Hz to 20-100 Hz (AR20) was significantly higher (P < 0.01) and the magnitude ratio at 30 Hz (%Mag.30) calculated by dividing the magnitude at 30 Hz by the maximal magnitude was significantly (P < 0.01) lower in patients with Paf than controls in the left lateral chest leads. The predictive accuracy of Paf with AR20 > or = 1.5 and that with %Mag.30 < 40% was 83% and 73%, respectively. Our results indicate that the frequency-domain analysis of P waves in lateral leads is useful as is the time-domain analysis to detect patients with Paf. The AR20 > or = 1.5 and %Mag.30 < 40% provides accurate predictability of Paf.

Adult↗

PubMed1998

Mitral valve prolapse and autonomic function in panic disorder.

We investigated the significance of mitral valve prolapse (MVP) and autonomic function in 121 patients diagnosed with panic disorder (PD). The incidence of MVP was higher in these patients (32.2%) than in the healthy controls (16.7%), but the difference was not significant. In the group with PD accompanied by depression, the MVP rate was 58.1%, significantly higher than the value of 25.7% observed in the PD patients without depression. The severity of MVP was mild; nearly all of the cases were silent, without cardiac murmur, and there was no problem with the left ventricular function. The coefficient of variation for R-R intervals on electrocardiograms (CV R-R) was smaller in patients with PD than in healthy controls. The CV R-R of PD patients was significantly lower in the group with MVP than in the group without MVP, suggesting a strong association with the parasympathetic nervous system. Since the CV R-R tended to decrease in the presence of depression, involvement of the parasympathetic nervous system was inferred.

Adolescent↗

PubMed1998

Entry and intracellular growth of Legionella dumoffii in alveolar epithelial cells.

We have found that Legionella dumoffii strain Tex-KL (ATCC 33343) invades into and proliferates in the human lung alveolar epithelial-cell line A549 in vitro. The organism associated with the A549 cells at a 10-fold greater magnitude than L. pneumophila Philadelphia-1 during in vitro coculture for 1 h. Thereafter, L. dumoffii Tex-KL invaded the cells at a significantly higher rate (100- to 1,000-fold) than did L. pneumophila Philadelphia-1. After internalization, however, both bacteria proliferated at the same rate. This in vitro finding led us to examine the bacterial localization in lungs in a fatal case of L. dumoffii pneumonia. Double immunostaining revealed the bacteria in surfactant apoprotein A-positive cells (i.e., type II alveolar epithelial cells). Next, we infected guinea pigs intratracheally with L. dumoffii Tex-KL. The animals became sick with a fever from 24 h to 48 h after infection with 10(4) to 10(9) cfu of L. dumoffii Tex-KL. The lung tissues were examined through electron microscopy at definite intervals. Many bacteria were found not only inside phagocytic cells in the alveolar space, but also in type I and type II alveolar epithelial cells. These findings strongly suggest that L. dumoffii has an ability to invade into and proliferate in human alveolar epithelial cells, which may explain the rapid and fulminant progress of pneumonia caused by L. dumoffii.

Animals↗

PubMed1998

Echocardiographic evaluation of cardiac valvular abnormalities in adults with Down's syndrome.

It is well known that congenital heart abnormalities are common in children with Down's syndrome. However there are few studies on cardiac abnormalities in adults with Down's syndrome. Therefore, we estimated cardiac abnormalities by means of echocardiography in 30 institutionalized Japanese adults with Down's syndrome, but without cardiac symptoms. Two-dimensional echocardiography showed an incidence of 26.7% in mitral valve prolapse and 20% increase of echo brightness in the mitral valve. Doppler echocardiography revealed an incidence of 16.7% in mitral valve regurgitation, and 13.3% in aortic valve regurgitation. Thus, even adults with Down's syndrome who are apparently free of cardiac symptoms may be at risk for valvular disease.

Adult↗

PubMed1998

[Congenital aortic regurgitation complicated by infective endocarditis of tricuspid valve due to spontaneous closure of ventricular septal defect: a case report].

A 32-year-old woman presented with a rare case of tricuspid valve endocarditis causing inflammatory reopening of the spontaneously closed ventricular septal defect (VSD), associated with aortic valve malformation. She was admitted to our hospital because of fever lasting 4 weeks. Severe aortic regurgitation was revealed by color Doppler echocardiography. Blood culture identified Microccus faecalis. Antibiotics were administered over 3 weeks, but serial echocardiography showed a developing vegetation in the right ventricle and left-to-right shunt flow. The diagnosis was infective endocarditis complicated by aortic ring abscess and interventricular septal fistula. Surgery performed on the 22nd hospitalized day found a vegetation of the tricuspid valve, a membranous type of VSD, and aortic valve malformation. Aortic valve replacement, patch closure of VSD, and tricuspid valvuloplasty achieved a successful outcome.

Adult↗

PubMed1998

[Echocardiographic and hematological variables as a risk factor for stroke in chronic nonvalvular atrial fibrillation].

The relationship between echocardiographic variables and the incidence of ischemic stroke in patients with atrial fibrillation was investigated by transthoracic and transesophageal echocardiography in 67 patients with chronic nonvalvular atrial fibrillation. Hematologic variables were also measured simultaneously, including plasma levels of D-dimer and thrombin-antithrombin III complex in these patients. There was a prior history of ischemic stroke in 13 patients (stroke group), but not in the other 54 patients (nonstroke group). There were no significant differences in age, sex, left ventricular ejection fraction, left ventricular end-diastolic diameter, left atrial diameter or hematologic parameters between the groups. The left atrial appendage emptying flow velocity was lower in the stroke group than in the nonstroke group (21 +/- 5 vs 32 +/- 3 cm/sec, p < 0.05), and the incidence of left atrial spontaneous echo contrast was significantly higher in the stroke group than in the nonstroke group (69% vs 26%, p < 0.01). There was no significant difference in the incidence of left atrial thrombi between the groups (23% vs 12%). These findings suggest that transesophageal echocardiographic variables are correlated with the risk of ischemic stroke in patients with chronic nonvalvular atrial fibrillation.

Adult↗

PubMed1998

[Successful removal of an infected pacemaker electrode adhered to the tricuspid valve].

A 77-year-old male suffered from pacemaker lead infection with pacing failure. Because he had a severe fever, we performed an interventional removal procedure with the help of a lead removal kit. However, the tip of the lead could not be withdrawn via the right internal jugular vein because it adhered tightly to the tricuspid valve. Two days later, we proceeded with an open removal procedure under cardiopulmonary bypass. The lead could be removed without any complication, and no inflammation was observed postoperatively. We report the case and discuss the indications and limitations of both the interventional and open methods.

Aged↗