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Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 1,351 records · Page 75Linked to original sources
PubMed1984

[Hemorrhage into tha cavity of chronic subdural hematoma].

Mean quantity of daily hemorrhage into the hematoma cavity was determined at the craniotomy in 39 cases with chronic subdural hematoma. Mean daily hemorrhage amounted 6.7 per cent of hematoma volume. Those in infancy, adults younger or older than 70 years old were 6.8%, 6.9% and 6.2%, respectively. When the period from head trauma till the craniotomy was less 3 months, one fourth of cases showed more bleeding than 10% of hematoma content into the cavity. Over 3 months after the head trauma, hemorrhage decreased in volume, amounted less than 2%. The severer the clinical grading of chronic subdural hematoma was, the more the daily hemorrhage was. The cases with dementia demonstrated usually less hemorrhage. The daily hemorrhage into the hematoma cavity did not correlate clearly with the maximum breadth of subdural hematoma in CT scans or carotid angiograms. Not only bleeding but also its dilution and condensation in the subdural hematoma modifies the density of hematoma cavity in CT scans. There were many cases showing more hemorrhage at FDP levels among 320 and 640 micrograms/ml. The hemorrhage into the chronic subdural hematoma cavity is caused by imbalance of local hyper-fibrinolysis and coagulability and daily hemorrhage amounts 6.7% of hematoma content. Such interrupted or continuous hemorrhage results in aggravation of clinical symptoms and high density of hematoma space in CT scans.

Adult↗
PubMed1984

[Chronology of medullary carcinoma of the thyroid].

In order to study the chronological progress of medullary carcinoma of the thyroid, clinical records and histological findings of 62 patients with the tumor were reviewed. Postoperative plasma calcitonin levels were examined in 54 patients. Among the patients with the disease of the hereditary type, those of 30 years of age younger with no lymph node involvement and a tumor weight less than 5 g were most likely to have normal plasma calcitonin levels postoperatively, provided total thyroidectomy were performed. The peak of age distribution of patients of the hereditary type without lymph node involvement was 15 years less than that of those with nodal involvement. In the sporadic type, there was no correlation between teh age and the nodal nodal involvement. Plasma calcitonin levels in the patients with residual tumor showed exponential increase according to the time course. The regression lines, log y = log a + bx (y: plasma calcitonin level, x: years after operation), were calculated in 23 patients followed 6 months or longer. The doubling time of the plasma calcitonin level (T2), given as 1/b log 2, correlated well with the tumor progression rate. T2 for patients of the hereditary type were 0.8 years or longer except for one. Four patients of the sporadic type with T2 of 0.1-0.3 year within 3 years after operation.

Adolescent↗
PubMed1984

[Experimental studies on polyacetal composites for joint prosthesis].

UNLABELLED: Composite polymer resin is one of the most promising materials for its excellent bio-functions. The purpose of the present studies is to prove the applicability of polyacetal composites as a biomaterial for joint prostheses from in vivo as well as in vitro experiments. MATERIALS AND METHODS: The polymeric materials tested in the studies were acetal copolymer resin (POM) reinforced with 20% carbon fiber (CR20), POM with 10% fluorine powder (YF 10), POM alone, ultra high molecular weight polyethylene (UHMWPE) and UHMWPE reinforced with 10% carbon fiber (Poly two). Experiment I: Evaluation of biocompatibility in vivo by injecting polymeric powders into the abdominal cavity of mice, and in vitro with a tissue culture method. Experiment II: Friction and wear tests with a slider and a plate under different lubricants, the slider was made of stainless steel or ceramic. Coefficient of friction and specific wear rate were measured, and the wear surface was observed with scanning electron microscope (SEM). Müller type acetabular cups used for the simulation test were made of reinforced POMs, UHMWPE, and Poly two. A walk simulator was made to test the tribological behavior of hip joint prostheses in which the frictional counterpart was made of ceramic. Roughness of the wear surface, and ultimate frictional torque were measured and the surface microstructure was observed with SEM. Experiment III: Application for joint replacement. As a first step, screwshaped test pieces were inserted into the proximal end of the tibia of Beagle dogs, and ultimate rotating torque was measured to investigate the degree of fixation of reinforced POMs to the bone. A hip joint prosthesis of self-locking and cementless type was made and implanted in 12 dogs. Nine dogs were sacrificed more than 24 weeks after the implantation and investigated radiographically and histopathologically. RESULTS AND CONCLUSIONS: Reinforced POMs showed similar biocompatibility as other biomaterials for joint prostheses. In the combination with ceramic, the coefficient of CR20 tends to decrease with the increase of load and prolapsed time. SEM findings showed low specific wear. After the simulation test, the surface of CR20 cup became smoother. Poly two showed almost the same frictional torque as CR20, but its reinforced carbon fibers seem to be easily drifted away from the wear surface. The CR20 test pieces showed as firm fixation to the bone as those of stainless steel. The implantation tests were excellent in 2 and good in 3 dogs at the point of fixation of the socket with the bone out of 9 dogs tested.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetals↗
PubMed1984

Enhancing effect of bile and bile acid on stomach tumorigenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The carcinogenic or cocarcinogenic effects of bile or bile acid on stomach carcinogenesis were investigated in inbred W rats. Bile or bile acid was introduced into the stomach by choledochogastrostomy or with food after the administration of N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) CAS: 70-25-7; 1-methyl-3-nitro-1-nitrosoguanidine] in drinking water. The animals that received MNNG and bile or sodium taurocholate (CAS: 145-42-6; N-choloyltaurine sodium salt) had a significantly higher incidence of hyperplastic and neoplastic lesions in the stomach mucosa than did the relevant MNNG-treated controls. The result suggested an enhancing effect of bile and sodium taurocholate in stomach tumorigenesis.

Animals↗
PubMed1984

Identification of 3 beta, 7 beta-dihydroxy-5 beta-cholan-24-oic acid in serum from patients treated with ursodeoxycholic acid.

An unknown bile acid was found by gas-liquid chromatography in the serum of patients who were administered ursodeoxycholic acid for the treatment of cholesterol gallstones. Identification of the chemical structure of the unknown bile acid was performed by the use of gas-liquid chromatography-mass spectrometry. Mass spectrum analysis of the methyl ester trimethylsilyl ether of the bile acid showed explicitly that this is dihydroxy-5 beta-cholanoic acid, since peaks at m/e 460 and 370 characteristic of methyl ester trimethylsilyl ether of dihydroxy bile acid were clearly exhibited. Sites of the two hydroxyl groups on the steroid nucleus were determined to be at the 3- and 7-positions by conversion of the bile acid to the corresponding dioxo-cholanoic acid and by comparison of the gas-liquid chromatographic behavior with those of authentic dioxo bile acids. Four authentic 3,7-dihydroxy-5 beta-cholan-24-oic acids were chemically synthesized and retention times and mass spectra of their methyl ester trimethylsilyl ether derivatives compared precisely with that of the unknown bile acid. The results indicate that the unknown bile acid is 3 beta, 7 beta-dihydroxy-5 beta-cholan-24-oic acid. Preliminary experiments suggest that 3 beta, 7 beta-dihydroxy-5 beta-cholan-24-oic acid is absent as amino acid-conjugated forms in serum. It is also suggested that the bile acid is excreted into urine but not into bile.

Bile Acids and Salts↗
PubMed1983

Thiol-containing peptide-hemin complexes as models of cytochrome P-450.

Nine different synthesized thiol tetra- and penta-peptides containing Cys-Ser, Cys-Thr, Cys-His, Cys-Tyr and Cys-Cys in the N- and C-terminals are proposed as new models of apo-P-450. The peptide-hemin complexes in the oxidized (Fe(III] form in solution were characterized by their optical and EPR spectra and found to show hydroxylation activity like that of P-450 enzymes on acetanilide. Although the EPR properties of the complex containing Cys-His and all complexes in the presence of pyridine were similar to those of P-450, the optical properties of these complexes were not completely similar to those of P-450. Based on these results, the sixth heme coordination site of P-450 was discussed.

Acetanilides↗
PubMed1983

Immobilized 3 alpha-hydroxysteroid dehydrogenase and dansyl hydrazine as a pre-labeling reagent for high-performance liquid chromatography with fluorescence detection of bile acids.

A high-performance liquid chromatographic method with fluorescence detection is described for the determination of bile acids and their conjugates. After enzymatic conversion of bile acids to 3-oxo-bile acids using the immobilized 3 alpha-hydroxysteroid dehydrogenase reactor column, 3-oxo-bile acids were extracted with a Sep-Pak C18 cartridge, labelled with dansyl hydrazine and then separated by high-performance liquid chromatography on a reversed-phase column. The eluate is monitored by a fluorophotometer at 365 nm (excitation) and 520 nm (emission). Reactions proceed quickly under mild conditions to give fluorescent derivatives. Linearity of the fluorescence intensity (peak height) with the amounts of various bile acids and their conjugates was obtained above 0.5-1.0 pmol. The method is sensitive, reliable and useful for the simultaneous determination of bile acids in biological samples.

3-Hydroxysteroid Dehydrogenases↗
PubMed1983

Fluorescence high-performance liquid chromatographic determination of free and conjugated bile acids in serum and bile using 1-bromoacetylpyrene as a pre-labeling reagent.

A fluorescence high-performance liquid chromatographic method is described for the determination of free and conjugated bile acids in serum and bile. Free and conjugated bile acids are extracted from serum or bile using a Sep-Pak C18 cartridge and then fractionated on a piperidinohydroxypropyl Sephadex LH-20 column. Free and glycine-conjugated bile acids are labeled with 1-bromoacetylpyrene in acetonitrile using dicyclohexyl-18-crown-6-ether as catalyst. Taurine-conjugated bile acids are hydrolyzed by cholylglycine hydrolase and then derivatized by the same reagent. Derivatized bile acids are separated stepwise on a reversed-phase column (Radial Pak A) using acetonitrile-methanol-water (A) (100 : 50 : 40) and (B) (100 : 50 : 20) as mobile phase. The eluate is monitored by a fluorophotometer at 370 nm (excitation) and 440 nm (emission). Linearities of fluorescence intensities (peak heights) with the amounts of free and conjugated bile acids were obtained between 50 pmol and 200 pmol for free bile acids and between 25 pmol and 100 pmol for glycine-conjugated bile acids, respectively. Recoveries from serum and bile samples are not less than 90%. This method is sensitive, reliable and useful for the simultaneous determination of free and conjugated bile acids in serum and bile.

Bile↗
PubMed1983

Evidence for human T cell lymphoma-leukemia virus infection of family members of human T cell lymphoma-leukemia virus positive T cell leukemia-lymphoma patients.

Sera of family members of patients from the United States, the Caribbean, and Japan, with human T cell lymphoma-leukemia virus (HTLV) associated T cell malignancies, possess HTLV-specific antibodies directed against internal structural components of HTLV, p24 and p19. The prevalence of antibodies to HTLV is greater in family members than in random healthy donors, which supports the infectious nature of HTLV and its association with particular aggressive T cell malignancies. Expression of HTLV p24 and p19 has also been observed in cultured T cells of some healthy relatives, and intact virus particles have been released from cells of one possibly pre-leukemic family member.

Antibodies, Neoplasm↗