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Biomedical subjects

M Miyagawa

Publications and source records attributed to M Miyagawa.

At least 73 records · Page 4Linked to original sources
PubMed1989

Overproduction and preliminary crystallographic study of ribonuclease H from Escherichia coli.

To facilitate the preparation of ribonuclease H from Escherichia coli in an amount sufficient for crystallographic studies, we have constructed an overproduction system for the enzyme. The structural gene for the enzyme was subcloned from pSK750 (Kanaya, S., and Crouch, R. J. (1983) J. Biol. Chem. 258, 1276-1281) to make a plasmid vector pPL801, in which the gene was under the control of bacteriophage lambda PL promoter. Thermal induction of the gene accumulated the enzyme in E. coli N4830-1 to approximately 8% of the total cytosolic protein. The level of production of the enzyme in N4830-1 harboring pPL801 was 14 mg/liter culture, which was 3000 times as high as that in the host cell. The enzyme was purified with a yield of more than 80% and crystallized by utilizing the property that the solubility of the enzyme decreased at pH values close to its isoelectric point (pI = 9). Crystals were grown by successive seeding (hanging drop method) for x-ray crystallographic analysis. The crystals belong to space group P212121 with unit cell dimensions of alpha = 44.1 A, b = 87.0 A, c = 35.5 A and contain one molecule in an asymmetric unit. They diffracted x-rays beyond 2.5 A resolution.

Bacteriophage lambda↗
PubMed1989

A unified computer program for assessment of attenuation correction and data acquisition methods in single photon emission computed tomography (SPECT).

A computer based simulation program was developed to assess the usefulness of various attenuation correction algorithms and data acquisition methods in single photon emission computed tomography (SPECT) in a unified approach. The program analytically calculated projection ray sums from a mathematical model with various distributions of activities and either uniform or non uniform attenuation coefficients by using the line integrals including the effect of attenuation. Data acquisition starting at arbitrary angles, various acquisition angles, including a 180 degree scan and a non circular orbit of a gamma camera, including an elliptical orbit can readily be taken into consideration in our simulation program. To simulate non circular orbit data acquisition, the resolution dependence on the object distance from the collimator surface was incorporated into the simulation. This computer based simulation program allows various combinations of attenuation correction algorithms such as hybrid methods, and data acquisition methods can be evaluated under a large number of study conditions. The usefulness of this computer based simulation program is shown with several representative examples.

Algorithms↗
PubMed1989

[Triple malignancy including bladder carcinoma, prostate carcinoma and malignant lymphoma: a case report].

A 70-year-old man was admitted to our hospital with the complaint of lower abdominal mass. Previously, he had received partial cystectomy and radiation of 38 Gy for bladder transitional cell carcinoma and transurethral resection of prostate and diethylstilbestrol administration for prostatic adenocarcinoma. The third tumor was located between the bladder and lower abdominal wall with inguinal lymph node swelling. Biopsy specimen revealed malignant lymphoma. After 2 courses of combination chemotherapy consisting of vincristine, prednisolone and procarbazine, complete remission was achieved. We discuss about multiple malignancies including urological organs.

Adenocarcinoma↗
PubMed1988

Pulmonary hypertension in progressive muscular dystrophy of the Duchenne type.

Right heart catheterization was performed in 8 patients with progressive muscular dystrophy of the Duchenne type (DMD) at the advanced stage. A mean pulmonary arterial pressure in excess of 20 mmHg was observed in all cases. Five of them showed severe pulmonary hypertension with a mean pressure above 40 mmHg. Since pulmonary hypertension was relieved by correction of hypoxemia, this represented a precapillary pulmonary hypertension caused by constriction of the pulmonary artery. Furthermore, elevation of the mean right atrial pressure above 5 mmHg was observed in 6 of the 8 cases, indicating the possible presence of right ventricular failure. Despite the presence of left ventricular dysfunction as assessed by echocardiogram, no manifestations of left ventricular failure, such as dyspnea and pulmonary rales, were noted in any of the patients. In conclusion, it can be said that even in the terminal stage of DMD, the left ventricular function may, in fact, still remain not markedly involved, and that respiratory failure, as well as right ventricular failure caused by precapillary pulmonary hypertension, will tend to occur frequently and may play a determinant role in prognosis of the advanced DMD patient.

Adolescent↗
PubMed1988

Protection of the rat myocardium from ischemic injury by dietary lamprey oil.

The lamprey (Entosphenus japonicus Martens) has been recommended in Japan as an efficacious diet for curing some of chronic inflammatory disorders. Fresh lamprey is rich in n-3 unsaturated fatty acids (e.g., eicosapentaenoic and docosahexaenoic acids) with minimal seasonal variation. The dietary effect of lamprey oil on acute myocardial ischemia was therefore investigated. Rats were fed a control diet or a diet supplemented with 5% safflower oil (SO) or 5% lamprey oil (LO) for 4 weeks. After coronary artery ligation, rats fed the LO diet demonstrated a higher 24-h survival rate and a reduced loss of creatine kinase activity from ischemic myocardium when compared with rats fed the control or SO diet. Moreover, the intracellular redistribution of lysosomal enzyme activity in the ischemic myocardium was significantly suppressed in the LO diet group. Analysis of the fatty acid composition of myocardial phospholipids in rats fed LO showed marked elevation of n-3 fatty acids, whereas arachidonic acid (n-6) content was significantly reduced. Hence, the n-3/n-6 ratio of myocardial phospholipids was markedly increased in the LO diet group. In addition, there was more than a 77% reduction in TXB2 synthetic capacity in whole blood in rats fed the LO diet when compared with rats fed either the control or SO diet. In conclusion, dietary supplementation with LO prevents sudden cardiac death and limits the extension of cellular damage from acute myocardial ischemia in rats. Both changes in thromboxane generation and altered membrane fatty acid composition may be involved in the observed reduction of ischemic damage in the heart.

Animals↗
PubMed1987

[Relationship between biopsy and prognosis of breast cancer].

Clinical data from 131 patients who underwent primary radical operation for breast cancer at the Second Department of Surgery, Shinshu University Hospital during five-years from January 1976 to the end of December 1980 were analyzed to investigate for the relationship between biopsy and prognosis. The incisional biopsy group had a significant higher recurrence rate as compared with the no biopsy group, cytology group and the cancer negative group after excisional biopsy. Although the puncture aspiration cytology group did not show significant difference in recurrence rate, an any more than 3 weeks of interval between puncture aspiration cytology and radical surgery associated with a significant high recurrence rate. This suggests that the interval also exerts an unfavorable influence upon prognosis. Puncture aspiration cytology was recognized to be apt to result in distant metastasis than any other biopsy methods and also it is tended to have a higher recurrence rate in scirrhous and mucinous carcinoma of the breast.

Adenocarcinoma, Mucinous↗
PubMed1987

[An autopsy case of plasmacytoma of the thyroid gland].

An autopsy case of a 75-year-old woman with plasmacytoma of the thyroid gland is presented. There were no toxic symptoms and no abnormal serum protein. On autopsy, a nodule measuring 5.5 X 4.5 X 8 cm was found in the left lobe of the thyroid gland. No myeloma lesions were found in the bone marrow or in other organs. Histologically, the marginal area of the nodule was occupied by typical plasmacytoma, whereas necrotic tissues resembling anaplastic carcinoma were present in the central portion. Chronic thyroiditis was not associated. Immunohistochemically, only the kappa-light chain was demonstrated in the cytoplasm of the tumor cells.

Aged↗
PubMed1986

[A case of Pick's disease with long duration--an extraordinary cerebral change in the fore part of cerebrum].

An autopsied case of Pick's disease, having an extraordinary cerebral change in the anterior portion of Lobus frontalis and temporalis, was reported. Our case is a 71 year-old woman at death with a fourteen year history of chronic progressive dementia and mental deterioration, and it may be stressed that the existence lasted 8 years, over the latter half of clinical course, was depended on the tube feeding. The first symptoms suddenly appeared in 1964, 2 months after her husband's death of illness, when she was 57. She prepared the table for breakfast late at night, calculated wrongly in her domestic account book, and stole foods in the grocery. Two years later, her illness was diagnosed as presenile dementia by characteristic personality change and marked dilatation of anterior horn of lateral ventriculus. On admission to National Musashi Sanatorium, three years after the first symptoms' appearance, she presented restless walking, insomnia, memory loss, weakness of concentration, and high degree of disorientation. Particularly, it was noticeable that she behaved with bizzare contact. After 1970, tube feeding was introduced continuously, because of swallowing difficulty. Death occurred in July 1978 from a general weakness and a broncho-pneumonia, 14 years after the onset of the first symptoms. Autopsy revealed small and atrophied brain weighed 820 g. Cerebral cortical atrophy extended to frontal, temporal, insular, and parietal lobes, but right T-1 was relatively well preserved. On section, frontal and temporal ventriculus were remarkably enlarged and caudate nuclei were extremely atrophic.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Neurotoxicity and metabolism of methyl bromide in rats.

Changes in locomotor activity, body temperature, and body weight gain, and the enhancement of thiopental-induced sleep were investigated in rats as indices of the functional changes in the CNS caused by methyl bromide (CH3Br) exposure. The correlations of these behavioral changes with CH3Br metabolism are discussed. The LC50 value and its 95% confidence limits for an 8-hr exposure of CH3Br was 302 ppm (267-340) ppm. Effects were examined following exposure to 63, 125, 188, or 250 ppm CH3Br for 8 hr. CH3Br concentrations as low as 63 ppm remarkably enhanced the sleep-inducing potency of thiopental, but CH3Br exerted no effect on thiopental metabolism. The body temperature and body weight gain were decreased at exposure to concentrations of 125 ppm or higher, and locomotor activity was reduced at 188 ppm or higher. These effects were reversible and, at 24 hr after the exposure, locomotor activity and body temperature were almost the same as in control rats. In a time-course study of CH3Br, bromine, and methyl alcohol, CH3Br was rapidly eliminated from rat tissues following the cessation of exposure, with a half-life of about 30 min in the early post-exposure period. In contrast, the elimination rate of bromine was very slow, with a half-life about 5 days. The methanol amount was below that reported to induce the changes in CNS functions. These results suggest that the CNS depression caused by CH3Br exposure may be due to the CH3Br molecule or the methyl moiety incorporated into tissues and may not be attributable to bromine or methanol. A linear relationship was obtained between bromine amounts in blood and the exposure concentration or duration. This result suggests the possibility that the extent of CH3Br exposure may be estimated from the bromine quantities in blood.

Animals↗
PubMed1985

Characterization of Ca2+ transport and enzyme activity in microsomes isolated from guinea-pig stomach smooth muscle.

Ca2+ uptake by microsomes prepared from guinea-pig stomach required the presence of both ATP and Mg2+ and was unaffected by NaN3. ATP-dependent Ca2+ uptake increased with increasing free Ca2+ concentration from 0.1 to 5 microM, and further increase in Ca2+ concentration above 5 microM did not enhance the uptake further. Half-saturation occurred at approximately 0.55 microM. The t1/2 values of Ca2+ loss from these vesicles loaded in the presence of oxalate were significantly slower than those in the absence of oxalate. Enzyme activity suggested linkage between Ca2+ uptake and ATPase activity, and most of the azide-sensitive component of ATP hydrolysis was attributable to potent inhibition of ADPase activity.

Adenosine Triphosphatases↗