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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 973 records · Page 54Linked to original sources
PubMed1989

Histopathological study of corpora amylacea pulmonum.

In this paper, we present a rare disorder which is known as corpora amylacea pulmonum. X-ray CT scanning showed an abnormal focus of the lung as a solitary mass with high density and spicular features around the surface. The resected lung tissue was characterized by the appearance of round, concentrically laminated acellular bodies about 40-80 microns in diameter. The bodies were usually found lying free in the alveolar space and surrounded by the exudate alveolar macrophages or multinuclear giant cells. Some of these macrophages were in a state of progressive degeneration. The bodies showed an affinity for Congo red and exhibited partial birefringence. Moreover, all the bodies had a strong positivity for the PAS reaction and anti lysozyme antibodies. The exudate alveolar macrophages and multinuclear giant cells also displayed reactivity for PAS and lysozyme in a similar manner to that of the bodies. Electron microscopically the bodies were fundamentally composed of fibrillar elements, which bore some resemblance to amyloid fibrils and probably accounted for the partial affinity of the bodies for Congo red. These amyloid-like fibrils were also found in the cytoplasm of the macrophages. This suggested that the concentrically laminated bodies in corpora amylacea pulmonum might be formed by sequential aggregation, fusion, coalescence and compaction of degenerated alveolar macrophages.

Aged↗
PubMed1989

[Degradation of polyurethanes in aqueous environment].

The effect of in vitro exposure to aqueous environments on the change of properties of polyurethanes was studied as a model experiment for understanding the in vivo degradation of polyurethanes. Films of three commercially available medical polyurethanes consisting of diphenylmethane diisocyanate (MDI) (Biomer, Cardiothane and TM-3) and an experimental segmented polyurethane based on hydrogenated MDI (HMDI) were immersed in phosphate buffer or HEPES buffer containing lithium chloride at pH 7.4 at 70 degrees C for up to one year. Samples were subjected to ATR-FTIR measurement, tensile testing and viscosity measurement. Stability to hydrolytic degradation increased in the order: HMDI, TM-3, Biomer and Cardiothane. This ranking was consistent with that obtained in vivo. The results suggest that an in vitro model experiment is helpful for understanding and predicting degradation performance of polyurethanes in vivo.

Hydrolysis↗
PubMed1989

[Recovery of fluoride orally on the acid-etched tooth surface].

There are many reports concerning the recovery phenomenon of acid-etched enamel surfaces of teeth. Many studies of surface hardness, acid resistant properties, radiolucency, and surface morphology suggest that orally the acid-etched enamel reverts to a state nearly similar to that of the intact enamel before the acid etching. This study was conducted in order to verify the existence of the recovery phenomenon of fluoride on acid-etched enamel, because the surface layer of a high fluoride concentration is removed from the surface enamel by the acid etching. The deciduous upper central incisors of both sides were etched with phosphoric acid. The fluoride content of one incisor was measured immediately after the etching and that of the opposite incisor was also measured in vivo after 4 weeks, during which period no special fluoride was used. The fluoride content of the tooth surface in the mouth after 4 weeks significantly increased by about 50 ppm, when compared to that immediately after the acid etching. No significant relationship was found between the fluoride increase and the fluoride concentration of the patients' saliva and drinking water which were the probable supply sources of fluoride for the teeth. No relationship was found between the fluoride increase and the number of second deciduous molars with defects or fillings, which was counted as a measure of the patient's susceptibility to caries.

Acid Etching, Dental↗
PubMed1989

[Studies on visible-light initiator system using thiobarbituric acid derivatives].

Experimental visible-light curing resins were prepared by the combination of dl-camphorquinone and a thiobarbituric acid derivative, such as 5-methyl-2-thiobarbituric acid (5 MS), 5-n-butyl-2-thiobarbituric acid (5 BS), and 1,3,5-trimethyl-2-thiobarbituric acid (135 MS). The ability of their initiator systems to polymerize resins was investigated and was also compared with that of initiator systems containing 5-n-butyl-barbituric acid (5 B) or N,N-dimethylaminoethyl methacrylate (DMAEMA) as the most popular reducing agent. The amount of insufficiently polymerized layer was small in 135 MS at a low concentration, and in DMAEMA at a high concentration, respectively. 135 MS was superior to DMAEMA in curing time, maximum exothermic rate and depth of cure at a concentration of 1.0 mole%. 135 MS, therefore, seemed comparable or superior to DMAEMA. The order of increasing activity as a reducing agent was 5 BS less than 5 MS less than DMAEMA less than or equal to 135 MS. When analogous 5 B and 5 BS were compared, the sulfur-containing 5 BS was more effective as a reducing agent.

Acrylic Resins↗
PubMed1989

[New acrylic resins with very low residual monomer].

New experimental acrylic resins were prepared by polymerization of MMA in the presence of vinylidene fluoride/hexafluoropropylene copolymer. The amount of residual monomer in the resins prepared by visible light curing, cold curing, and heat curing, at various polymer/monomer ratios, was measured and compared with the usual MMA/PMMA resin. In the visible light cured resins containing 60 or 70 wt% of the fluoropolymer, the amount of residual monomer was less than 0.1%. In the cold cured resins, the amount of residual monomer was very low: 0.2% and 0.7% for the resins containing 70 and 60 wt% of the polymer, respectively. These values were comparable to the usual heat cured MMA/PMMA resins. In the heat cured resins, the amount of residual monomer was the lowest; less than 0.1%, even in the resin consisting of 50 wt% polymer. Thus, we prepared new acrylic resins with much less residual monomer than the usual MMA/PMMA resins.

Acrylic Resins↗
PubMed1989

Endogenous sex hormone and estrogen binding activity in thyroid cancer.

The reactions of four anti-sex hormone (Estrone, Estradiol, Estriol and Testosterone) antisera were immunohistochemically examined in 109 cancerous and 80 normal and benign thyroid tissues. Four kinds of sex hormones were detected in the tumour cells of 61 cases (56%) of thyroid cancer and in the follicular epithelial cells of 4 cases (5%) of normal and benign thyroid tissues. Among the thyroid cancers, 54 female (61%) and 7 cases in males (33%) were positive for sex hormones. Furthermore, estrogen binding activity was screened histochemically in 36 thyroid tissues of various types, and detected not only in thyroid cancer (6/15 cases), but in normal and benign thyroid tissues (4/21 cases) as well. It was concluded that endogenous estradiol was located in thyroid cancers more frequently in females than in males and that there was estrogen binding activity in the cells of not only thyroid cancers, but also normal and benign thyroid tissues. This is the first report of the demonstration of endogenous sex hormones in thyroid cancer.

Adolescent↗
PubMed1989

IBL-like T cell lymphoma expressing monoclonal gammopathy (macroglobulinemia) in the serum.

A case of IBL-like T cell lymphoma with serum monoclonal gammopathy was reported. A 58-year-old woman, who had suffered from heart failure, was admitted because of asthma attack, fever and lymphadenopathy. Leucopenia with a small amount of atypical lymphocytes was detected. Serum analysis showed monoclonal elevation of IgM-kappa (M-protein) and hyperviscosity. Urinary Bence-Jones protein was detected. Lymph node biopsy revealed the disappearance of normal structure and proliferation of T cells with pale cells which characterized IBL-like T cell lymphoma. Immunocytochemistry revealed the pale cells to bear T cell markers (MT-1, CD 5, CD 8 or CD 4) and IgM-positive cell distribution. Tonsilar biopsy showed the infiltration of atypical lymphoids and pale cells. Bone marrow biopsy showed moderate lymphoplasmacytoid proliferation with lymph follicles. Clinical data and serum analysis suggested macroglobulinemia. Additional lymph node biopsy was performed and revealed IBL-like T cell lymphoma. IBL-like T cell lymphoma is characterized by polyclonal hypergammaglobulinemia. The present case probably occurred initially as IBL-like T cell lymphoma and lymphoplasmacytoid cell proliferation might have followed due to an excess of CD 4+ cells.

Bone Marrow↗
PubMed1989

[A case of successful surgical treatment of straddling tricuspid valve associated with dextrocardia and VSD].

A case of straddling tricuspid valve associated with dextrocardia and VSD was presented. Closure of ventricular septal defect and tricuspid valve replacement were performed on this patient. Since the straddling septal leaflet of the tricuspid valve shared a posterior papillary muscle in the left ventricle with the posterior mitral leaflet, division of this papillary muscle was thought to induce papillary muscle dysfunction of both leaflet. Hence, the chordae of straddling tricuspid leaflet was detached from the shared papillary muscle and the ventricular septal defect was closed by a large pericardial patch. Because of peculiar anatomy of the conduction system in this situation, the junctional area of the inlet septum and tricuspid annulus was avoided from stitching in VSD closure. Suture through the tricuspid septal leaflet and pericardial patch for VSD were used for tricuspid valve replacement as well. The patient showed uneventful postoperative course without any conduction disturbance including the right bundle branch block.

Adult↗
PubMed1989

[Chemical change of calcium hydroxide contained in root canal filling materials in serum].

In the previous report we showed the conversion of calcium hydroxide contained in root canal filling materials to calcium carbonate by means of 4 weeks of subcutaneous implantation in rats. The purpose of this study was to discover if this reaction would take place in vitro as a chemical reaction and also to find out the rate of the conversion. The alteration of three materials. Vitapex, Calvital, calcium hydroxide, when in serum, was checked and the alteration of the latter two, when in the air, was checked. The solubility of calcium hydroxide in serum or distilled water was also determined. The results showed that calcium hydroxide was neutralized to calcium carbonate after several weeks in the serum. The conversion in the air was much slower than that in the serum. This means that calcium hydroxide will not change while in storage and when it has no contact with the tissue fluid. Calcium hydroxide was dissolved in both the serum and distilled water, but calcium carbonate was not. This fact suggests that calcium hydroxide neutralized to calcium carbonate by serum will cause little or no chemical irritation.

Animals↗
PubMed1989

[Study on gypsum hardener].

The purpose of this study was to search for an appropriate condition for shortening the treatment time of gypsum hardener, Plaster Aid. In order to keep the increased strength of plaster with this new hardener, compressive strength and dimensional change in various conditions of heating temperature, heating time and drying time were examined. The following results were obtained. 1. High compressive strength was maintained in the condition of 70 degrees C of heating temperature, with more than 15 minutes of heating time and more than 15 minutes of drying time. In this condition up to 90 minutes could be saved in comparison with the conventional method. 2. Plaster models had a tendency to shrink in the condition of 70 degrees C of heating temperature.

Calcium Sulfate↗
PubMed1989

[An immunohistochemical study of endogenous estradiol and testosterone in human colo-rectal cancer tissues].

An immunohistochemical method (peroxidase antiperoxidase method) was carried out to examine the distribution of endogenous estradiol (E2) and testosterone (Te). One hundred and twenty four (48.2%) of 257 colo-rectal cancer cases, and 36.7% of male cases and 58.4% of female cases revealed E2-immunostain. This immunohistochemical reaction for E2 was found more frequently in female patients than in male patients, while Te-immunostain was found in 15 (17.6%) of 85 colo-rectal cancer cases. E2 and Te were demonstrated mainly in the cytoplasms and occasionally in the nuclei of cancer cells. Since E2 or Te-positive cancer cells were mainly distributed in the deeper or invasive portion of tissue sections, it might deserve further investigation to elucidate a certain relationship between cancer growth and endogenous sex-hormones.

Colorectal Neoplasms↗
PubMed1989

[Effect of fluoride of copper and iron on polymerization of MMA/TBBO resin and adhesion to dentin].

As a model experiment to understand the mechanism of adhesion of the MMA/TBBO resin to dentin, polymerization of MMA/TBBO was investigated in the presence of a collagen sheet treated with the aqueous citric acid (CA) solutions of copper fluoride (CF), ferric fluoride (FF), or ferric chloride (FC), which is usually used as a treating agent in bonding of the resin to dentin. The curing time of MMA/TBBO resin was considerably reduced in the presence of collagen treated with CF-CA or FF-CA solutions when compared to that with FC-CA solution. Molecular weight of PMMA depended on the site of polymerization; PMMA polymerized inside the collagen sheet was the highest and that polymerized outside was the lowest. Bond strength to dentin treated with CF-CA, FF-CA solutions was as strong as that treated with FC-CA solution. Treatment of dentin with CF-CA or FF-CA was as effective as that with FC-CA in bonding the MMA/TBBO resin. These results suggested that ferric compounds adsorbed to collagen are involved in polymerization of MMA and thus influence bond strength of the MMA/TBBO resin to dentin.

Adhesiveness↗
PubMed1989

Percutaneously adjustable pulmonary artery band. An experimental study.

Several forms of congenital heart lesions with increased pulmonary flow can be effectively palliated by pulmonary artery banding. In addition, banding has aroused renewed interest to induce left ventricular hypertrophy in infants with simple transposition of the great arteries. Occasionally a need arises to readjust the band to obtain an optimal degree of banding after operation. For percutaneous control of the degree of constriction after pulmonary artery banding, we developed a readjustable vessel occluder. The occluder consists of a stainless steel snare coated with polyethylene, an enveloping polyvinyl catheter (5F and 8 to 12 cm in length), and a screw adjuster, which is a stainless steel cylinder, 7 by 20 mm, containing a bolt and a nut. By means of a specially designed needle driver (1.0 mm in diameter), the screw adjuster can easily be driven percutaneously without a skin incision. The maximum stroke of the screw is 14 mm by 34 revolutions. One complete revolution of this screw corresponds to a change in diameter of 0.14 mm and to a change in circumference of 0.44 mm. Six mongrel dogs ranging in weight from 5 to 10 kg underwent banding of the pulmonary artery or the ascending aorta with this device. Follow-up evaluation by cardiac catheterization and angiocardiography was performed up to 2 months after implantation of the device. This band could be effectively and finely adjusted up to 2 months after implantation and no complication was seen. This preliminary study suggests that this new device may be applicable in patients with congenital heart disease and excessive pulmonary blood flow.

Animals↗
PubMed1989

[Successful repair of a coarctation complex with an anomalous right subclavian artery in an infant].

A 46-day-old infant weighing 2250 g with the coarctation of the aorta, ventricular septal defect, PDA, the anomalous right subclavian artery, and the persistent left superior vena cava initially underwent by the reversed subclavian flap aortoplasty with the anomalous right subclavian artery and pulmonary arterial banding. The reversed subclavian flap aortoplasty was useful for the coarctation complex with the anomalous right subclavian artery. Two months later he gained weight to 2500 g, and then VSD closure and debanding of PAB was performed successfully. This two-staged operation was recommended for the poor risk coarctation complex with the anomalous subclavian artery.

Aortic Coarctation↗
PubMed1989

[Experimental study on the optimal size of the tricuspid valve annular area on annuloplasty].

The optimal size of tricuspid valve annular area (TVAA) by annuloplasty for tricuspid regurgitation remains controversial. Recently, we developed a new measuring system which permits to do real-time measurement of tricuspid valve annular area in anesthetized dogs. Using this system, we studied the optimal size of TVAA by annuloplasty. After the right atrial incision, a metal thread which functions as a sense loop of the electromagnetic fields was stitched along the tricuspid valve annulus (visible juncture of the valve leaflets and the cardiac wall). The drive coil assembly was placed perpendicular to the extension of the long axis of the heart and was directed toward the tricuspid valve region. During control conditions, the maximum TVAA appeared at the onset of ventricular systole. The minimum TVAA appeared during the early ventricular diastolic phase which included the ventricular isovolumic relaxation phase. The maximum TVAA varied in five dogs between 2.2 cm2 and 3.1 cm2, the minimum TVAA also varied between 1.8 cm2 and 2.5 cm2: During regular sinus rhythm, a decrease of TVAA during one cardiac cycle ranged between 11.9% and 22.4% of the maximum size. When TVAA was not decreased by annuloplasty to the minimum area which was observed during cardiac cycle in the control state, the cardiac output and the right atrial pressure remained unchanged, because the ventricular filling was not obstructed. On the other hand, when TVAA was decreased smaller than this minimum area, the cardiac output decreased and the right atrial pressure rose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗