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Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 631 records · Page 35Linked to original sources
PubMed1990

Modification of swine serum-induced bile duct lesion in BALB/c mice by cyclophosphamide.

Effects of cyclophosphamide (CY) on the antibody titer level and incidence and severity of swine serum (SS)-induced bile duct lesion (BDL) were examined. BDL induced by 0.2 ml of SS per head twice a week for 2 weeks was characterized by hyperplasia of biliary epithelial cells, proliferation of mucous glands, and periductal infiltration of eosinophils with mild fibrosis. CY showed no significant influence on the above-mentioned parameters at the dose levels of 140 and 210 mg/kg. On the other hand, CY lowered the antibody titer level and decreased the severity of BDL at the dose level of 280 mg/kg, and it suppressed the antibody response and BDL at the dose level of 280 x 2 mg/kg. Thus the antibody titer level and the severity of BDL were closely related each other.

Animals↗
PubMed1990

[The method of esthetic crown restoration with composite resin jacket crown in primary molars].

The term "esthetics" has recently been also used in the dental field, and a field called esthetic dentistry is increasingly being noted. The number of not only adult but also pediatric patients who visit for treatment aiming at esthetic recovery is being increased. Inpedodontics, composite resin of the coronal color is generally used in the restoration of deciduous incisors. However, the method using metal crowns for the deciduous teeth is used for the deciduous molars at present. We applied a composite resin jacket crown to the deciduous molar in a way similar to that of esthetic crown restoration for the anterior teeth. The surgical procedure before crown preparation varied slightly according to the presence or absence of pulpal treatment of vital teeth and with non-vital teeth, but the application was performed as follows: 1) Desensitization of pulp, pulpal treatment and core construction. 2) Preparation of crown. 3) Selection, trial set and occlusal equilibration of a metal crown for the deciduous tooth. 4) Precision impression with a silicone impression material. 5) Removal of the metal crown for the deciduous tooth from the impression material. 6) Making of an under-cut to the abutment tooth on the buccal lingual side. 7) Filling of the impression with chemical polymerization resin. 8) Application of pressure in the oral cavity. 9) Adjustment of edge and crown forms. Thus, the preparation method for the composite resin jacket crown was relatively simple. Since this surgery, the patient has been followed up for 1 year and 6 months, and no specifically troublesome points have been observed clinically. The patient and her parents are satisfied with the results.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1989

[Digital radiography: fundamentals and future potentials].

Digital radiography consists of four major steps which include X-ray detection, digitization, image processing and display. Important parameters in digitization process is the pixel size and the number of grey levels which affect the quality of digitized images. A number of digital radiographic systems have been or are being developed which include the point-beam, line-beam, slot-beam and multiple slit-beam systems as well as conventional wide-beam systems such as image intensifier-TV system, storage phosphor system and film-based system. Important physical properties of digital radiographic systems are the sensitivity, resolution, noise, system response, scatter rejection, contrast sensitivity and image acquisition time. The resolution property is affected by the pixel size, sampling distance, display pixel size, image processing, detector response and X-ray beam characteristics. From ROC studies on chest images, the pixel size of approximately 0.2 mm and the corresponding image matrix of about 2,000 x 2,000 is considered optimal choice of these parameters. Future potentials of digital radiography are likely to be in the areas of computer-aided diagnosis (CAD) and PACS. Preliminary results obtained from recent studies on quantitative analysis of digital radiographic images are promising. The rms variation and the first moment of the texture of abnormal lungs with various interstitial diseases were clearly different from those of normal lungs. Automated detection scheme of nodules in chest images indicated approximately 70% true positive rates and a few false positives in each lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

Progesterone induces transient changes in plasma membrane fluidity of amphibian oocytes during the first meiotic division.

Progesterone acts at the surface of the amphibian oocyte to induce resumption of the meiotic divisions. Progesterone binding leads to a transient dose-dependent decrease in the fluidity (increase in order parameter) of the Rana oocyte plasma membrane, which was detected by electron spin resonance in isolated plasma membranes using either 5- or 16-DOXYL stearic acid probes. The 5-DOXYL probe, which inserts into the membrane with the spin label nearest the surface, showed an increase in the order parameter within minutes, a maximum change by 2 h, and a return to control levels by 6 h. The order parameter for the 16-DOXYL probe, which reflects the fluidity deeper within the plasma membrane, increased slowly and remained elevated during the first meiotic division. RU 38486, a synthetic steroid that blocks progesterone receptors, prevents progesterone-induced fluidity changes. These findings indicate that the binding of progesterone to its receptor changes the oocyte plasma membrane structure resulting in a differential decrease in mobility near the membrane surface compared to that deeper in the membrane.

Animals↗
PubMed1989

Comparative study of the use of prefabricated bone tendon grafts and conventional tendon grafts in flexor tendon reconstruction.

In tendon grafting the weakest area is the junction between the grafted tendon and bone. In dogs a strong union between tendon and bone can be produced by threading the flexor carpi radialis tendon through a hole drilled in the radius. In experimental repair of canine flexor tendons, 3 weeks after operation the strength of the union between a composite bone-tendon graft prepared in this way is double that of the bone-tendon junction of a conventional graft. Use of prefabricated bone-tendon grafts should permit earlier postoperative movement and limit formation of adhesions between a tendon graft and its bed.

Animals↗
PubMed1989

Measurement of absolute flow rate in vessels using a stereoscopic DSA system.

We used a stereoscopic digital subtraction angiography (DSA) system to measure absolute blood flow rates in vessels. The magnification factor and the three-dimensional orientation of a selected vessel are obtained from automated analysis of stereoscopic DSA images. The cross-sectional area of the vessel is determined from the vessel diameter, which is measured with an iterative deconvolution technique. The time required for fluid to flow through a selected segment of a vessel is determined from the automated analysis of contrast medium 'time-density' curves. The effectiveness of these combined techniques was demonstrated in measurement of rates of both continuous and pulsatile flow in a vessel phantom, with the actual flow rate calibrated volumetrically or by an electromagnetic flowmeter. We have obtained accuracies in measured flow rates of approximately 5% and 18% for continuous and pulsatile flow respectively.

Angiography↗
PubMed1989

Primary amyloid tumors of the jejunum producing intestinal obstruction.

The proximal jejunum, containing four separate amyloid tumors, was resected from a chronically constipated 71-year-old male exhibiting IgG lambda monoclonal gammopathy. Amyloid was deposited in the jejunal wall, mesentery and regional lymph nodes, but was not seen in gastric and rectal biopsy samples. Two years after surgery, the patient is well, but the monoclonal gammopathy persists.

Aged↗
PubMed1989

Multicentric astrocytomas of the optic chiasm, brain stem and spinal cord.

Autopsy was performed on a 52-year-old man with a 20-year history of neurological symptoms. At autopsy, both a brain stem tumor and a spinal cord tumor were found. These showed the features of pilocytic astrocytoma histologically. A pilocytic astrocytoma was also found in the optic chiasm upon microscopical examination. These three tumors were thought to be multicentric astrocytomas, because there was no continuity among them and no evidence of dissemination or metastasis by any pathway. From a review of the literature, the present case is considered to be an exceedingly rare one because of the multicentric sites of occurrence.

Adult↗
PubMed1989

Digital imaging of the chest.

During the past several years, image acquisition in nuclear medicine, computed tomography, ultrasonography, subtraction angiography, and magnetic resonance has been by digitization. Despite these advances, research in the development of digital imaging in conventional radiography has lagged behind. Although studies with a variety of digital techniques have been carried out on several fronts, we still do not possess a method that has captured the imagination of the majority of radiologists and other physicians to a point where it could replace conventional screen-film imaging. This article reviews the current status and general principles of the technology, focusing on the four digital radiographic techniques that have shown the greatest promise - film digitization, an image intensifier - based system, photostimulable phosphor plates, and a scanned projection system. The physical aspects of each of the four systems and the clinical results that have been reported to date, as well as the advantages and disadvantages of each system, are presented.

Humans↗
PubMed1989

Experimental encephalomyocarditis virus infection in Mongolian gerbils (Meriones unguiculatus).

Two strains of Mongolian gerbils (Meriones unguiculatus), Tumble Brook (TUM) and Japan Medical Science (JMS), were intraperitoneally inoculated with the D variant of encephalomyocarditis virus (EMC-D) and killed 3 days later. Mortality was significantly higher in females than in males. Evidence of viral replication was detected in the heart of both strains and in the pancreas of the TUM strain. Histopathological alterations were found in the heart and pancreas. Heart lesions involved foci of necrosis with inflammatory cell infiltration and calcification in both strains. Pancreatic lesions were restricted to the exocrine glands; islets of Langerhans were rarely and secondarily involved in the extensive destruction of exocrine glands. Severe acinar cell necrosis with marked inflammatory edema was conspicuous in TUM, whereas only slight acinar cell involvement was detected in JMS gerbils. Immunoperoxidase staining showed viral antigens in intracytoplasmic vacuoles in damaged acinar cells.

Animals↗
PubMed1989

The effect of immunosuppression on vascularised allografts. A preliminary report.

Five vascularised allografts of the knee joint were performed in dogs immunosuppressed with cyclosporin A and azathioprine. Three survived with normal function for 3 to 4 months after operation. One of the unsuccessful grafts had a failed vascular anastomosis, the other an inadequate blood level of cyclosporin A. All three successful grafts healed well. In two, bone scans, radiographs and biopsies were indistinguishable from successful autografts; in the third the blood supply to the graft failed despite patent anastomoses but the graft healed well with good function. All three grafts were rejected within 2 to 3 weeks of withdrawal of cyclosporin A and azathioprine. In non-immunosuppressed dogs, allografts of the knee, both vascularised and non-vascularised, were rejected within a few days of operation. In two non-vascularised allografts, administration of cyclosporin and azathioprine had no apparent effect on the rate of rejection of the graft.

Animals↗
PubMed1989

Initial lesions in the mouse brain induced by intraperitoneal injection of hypertonic saline.

A dose of 30 ml/kg of 8.5% solution of sodium chloride was intraperitoneally injected into ddY mice and time course observations were conducted. Colloidal carbon was infused 6 hr after injection and distribution of carbon in the brain was observed. A transient increase in hematocrit value, serum osmotic pressure and ascites was observed 1 hr arter injection. Distribution of colloidal carbon in the brain showed less penetration of the basal ganglia. Histopathological examination of the brain showed degeneration of pyramidal cells in hippocampus 6 hr after injection. Electron microscopical examination revealed intracytoplasmic microvacuoles, swollen mitochondria and dilated cisternae in rough-surfaced endoplasmic reticulum of pyramidal cells. It was suggested that serum viscosity was increased by rapid transport of water from blood into the peritoneal cavity or urine, due to the high osmotic pressure of hypertonic saline injected, resulting in a decrease in blood flow and ischemic changes in the brain.

Animals↗
PubMed1989

Susceptibility of four species of small rodents to encephalomyocarditis (EMC) virus infection.

The D variant of encephalomyocarditis virus (10(1)-10(5) PFU/head) was intraperitoneally inoculated into 4 species of small rodents, rats, mice, Syrian hamsters, and Mongolian gerbils, and the susceptibility of these animals to EMC virus was examined virologically and histopathologically 3 days after infection. Viral replication was detected in the brain (mice), in the heart (mice and gerbils), and in the pancreas (mice, hamsters, and gerbils). No viral replication was detected in rats. Histopathological changes were seen in the brain (mice and hamsters), in the heart (mice and gerbils), and in the pancreas (mice, hamsters, and gerbils). No histopathological changes were seen in rats. The present results suggest that it may be quite possible to produce EMC virus-induced diabetes mellitus not only in mice but also in hamsters and gerbils.

Animals↗
PubMed1989

Cardiodynamic factors affecting hyperpnea during steady-state exercise in man.

In order to know the role of cardiodynamic factors for exercise hyperpnea, ventilation and several cardiorespiratory variables were measured simultaneously in human subjects during exercise. Cardiac output (Q) and mixed venous CO2 content (CVCO2) were determined by a rebreathing method. The correlation coefficients (r) for the relationships between minute expiratory ventilation (VE) and each of end-tidal CO2 tension (PETCO2), Q, CVCO2, CO2 flow into the lung (QCO2, the product of Q and CVCO2), oxygen consumption (VO2), and CO2 output (VCO2) were determined during the steady-state exercise up to 90 W. The correlation was highly significant (r = 0.84-0.99, p less than 0.001) in each case except for PETCO2 (r = 0.13, N.S.). The highest correlation was observed in the VE-VCO2 relationship. It was assume that VCO2 released from the pulmonary capillaries into the alveoli is the most likely stimulus leading to exercise hyperpnea. Arterial CO2 oscillation may be regarded as a potential linkage between VCO2 and VE.

Adult↗
PubMed1989

A comparison between cardiac output determined by impedance cardiography and the rebreathing method during exercise in man.

Cardiac output was determined by impedance cardiography (Q(imp)) and a rebreathing method (Q(reb)) during exercise of loads up to 90 W. The correlation between Q(imp) and Q(reb) was generally good, but it was found in two of four subjects that Q(imp) was slightly lower than Q(reb) at the higher exercise levels. The regression equation for both Q values was: Q(imp) = 0.91 Q(reb) + 0.25 (l/min, r = 0.87, p less than 0.001).

Adult↗