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Biomedical subjects

M Yamato

Publications and source records attributed to M Yamato.

At least 55 records · Page 3Linked to original sources
PubMed1999

The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study.

The role of MRI in assessing facet joint osteoarthritis is unclear. By developing a grading system for severity of facet joint osteoarthritis on MRI, the relationship between disc degeneration and facet joint osteoarthritis was determined. The accuracy of MRI in assessing facet joint osteoarthritis against CT was 94%. Under 40 years of age, the degree of disc degeneration varied among individuals. Over the age of 60, most of the discs were markedly degenerated. Under 40 years of age osteoarthritic changes in facet joints were minimal. Over the age of 60, variable degrees of facet joint osteoarthritis were observed but some facets did not show osteoarthritis. No facet joint osteoarthritis was found in the absence of disc degeneration and most facet joint osteoarthritis appeared at the intervertebral levels with advanced disc degeneration. Disc degeneration is more closely associated with aging than with facet joint osteoarthritis. The present study supports the hypothesis that "disc degeneration precedes facet joint osteoarthritis", and also supports the concept that it may take 20 or more years to develop facet joint osteoarthritis following the onset of disc degeneration.

Adult↗
PubMed1999

Growth factor and matrix molecules preserve cell function on thermally responsive culture surfaces.

Thermally-responsive culture surfaces were designed using copolymers of N-isopropylacrylamide, 4-(aminomethyl)styrene, and acrylic acid. These surfaces contained functional amine and carboxyl groups, which allowed biomolecules to be grafted by amide formation. Epidermal growth factor (EGF), and extracellular matrix (ECM) molecules (collagen type IV, and chondroitin sulfate) were investigated, as surface-grafted biomolecules, for their ability to stimulate cell attachment, proliferation, and function by signaling only from the basal side of cultured cells. Surface analysis of biomolecule-grafted porous inserts showed covalent binding of biomolecules to either amine or carboxyl groups. Multiple attachment to amine and/or carboxyl groups served as cross-linking points that made the polymer hydrogel permanently adherent to the culture surface. Immunofluorescence microscopy techniques gave positive identification of grafted biomolecules. Grafting of EGF improved cell proliferation versus that on nongrafted controls, or controls grafted only with ECM molecules. ECM grafting induced cell attachment on attachment-resistant surfaces. Analysis of trans-epithelial resistance, fluid transport, and polarized g-glutamyl transpeptidase activity indicated that simultaneous grafting of both EGF and ECM produced better polarized cell function than nongrafted controls, or controls grafted with only one type of biomolecule. Covalent grafting of biomolecules did not interfere with cells ability to detach from thermally responsive surfaces upon temperature decrease.

Amides↗
PubMed1998

Active platelet movements on hydrophobic/hydrophilic microdomain-structured surfaces.

The early motion and interaction of platelets on a microdomain-structured block copolymer surface composed of 2-hydroxyethyl methacrylate (HEMA)-styrene were analyzed and compared with those on a compositionally identical random copolymer, homopolymer poly (HEMA) (hydrophilic) and polystyrene (hydrophobic) surfaces. Contacting platelets were quantitatively more active, with motions including rolling, detachment, oscillatory vibration, and change of direction only on the HEMA-St block copolymer surface. Active platelet movements were observed for long time periods (>20 min) on HEMA-St block copolymer surfaces and were distinct from those for inert PSt latex particles on these same surfaces, demonstrating that platelet movements were not due to physical forces such as convection, hydrophobic interactions, or microbrownian movement. To study the cause and mechanism underlying the platelet movements, platelets treated with an adenosine triphosphate (ATP) synthesis inhibition, NaN3, or a membrane skeleton-disrupting chemical agent, dibucaine, were also studied on these surfaces. Both treatments reduced platelet movement and demonstrated that platelets in contact with the HEMA-St block copolymer surface require metabolic processes consuming ATP and involve dynamics of their membrane skeleton. These energy-consuming active movements might explain the previously observed lower platelet activation and low thrombogenicity of the HEMA-St block copolymers. Enhanced platelet movements on the HEMA-St block copolymer surface show that the microdomain surface interacts uniquely with platelets to hinder activation and preserve passive platelet function despite surface contact.

Adenosine Triphosphate↗
PubMed1998

Release of spirosin associated with potassium phosphate-induced autolysis in Lactobacillus reuteri DSM 20016.

We have studied the effect of medium components on spirosin production in Lactobacillus reuteri DSM 20016 to get some insight into the function of spirosome in Lactobacillus. Among those investigated, only potassium phosphate was found to influence the production of spirosin. Though it was not effective at concentrations lower than 0.6%, it promoted the spirosin production and its accumulation into culture medium in particular, at higher concentrations. The accumulation has been demonstrated to originate inthe release of spirosin due to the bacterial autolysis induced by the higher concentrations of potassium phosphate, The autolytic effect of potassium phosphate was assumed to be a concerted action by phosphate and potassium ions at the concentrations higher than 0.1 and 0.4 M, respectively. A possible role of spirosin as a sensor protein of bacterial two-component regulatory system was discussed.

Antibodies, Monoclonal↗
PubMed1998

Analysis of matrix protein components of the dermis-like structure formed in a long-term culture of human fibroblasts: type VI collagen is a major component.

Formation of a dermis-like structure by a long-term culture of fibroblasts in the presence of ascorbic acid is a potential model for tissue organization or wound healing, and has its practical use as a skin graft. In the present study, solubilization of the dermis-like structure without pepsin treatment was attempted for analysis of pepsin-labile matrix components that might be involved in the formation of the dermis-like structure, as well as quantification of mutated type I collagen that could be susceptible to pepsin. The whole dermis-like structure was dissolved in a Tris buffer containing SDS and urea at 80 degreesC. Analysis of the extract by SDS-PAGE revealed several protein bands that were not found in the pepsin-treated extract. Among them, the polypeptide band migrating at 140k under reducing condition showed a similar intensity of protein staining to the alpha2(I) chain band. The N-terminal amino acid sequences of cyanogen bromide peptides derived from the 140k polypeptide band as well as the amino acid composition of the band suggested that the band essentially consisted of alpha1(VI) and alpha2(VI) chains. The results demonstrated that the type VI collagen was a major component, being a comparable in amount to type I collagen, in the dermis-like structure.

Adolescent↗
PubMed1998

Effects of certain resorcinol derivatives on the tyrosinase activity and the growth of melanoma cells.

Effects of certain resorcinol derivatives on tyrosinase activity, melanin formation and some other biological activities were studied in order to develop a new, potent depigmentor and/or antimelanoma drug. NKO-09, having isopentyl group in position 6 of resorcinal, exhibited a more potent effect than the compounds which have methyl (NKO-10), ethyl (NKO-11), hexyl (KOM-14), octyl (NKO-14), decyl (NKO-19), dodecyl (NKO-15) and tetradecyl (NKO-16) group in inhibiting the tyrosinase activities (both tyrosine hydroxylation and dopa oxidation). NKO-09 was more potent than hydroquinone in inhibiting the tyrosine hydroxylation; furthermore, NKO-09 inhibited the dopa oxidation different from hydroquinone. In the studies on melanin formation, protein synthesis and the growth of the melanoma cells, NKO-09 caused the most potent effect among the test compounds, except for the growth of the melanoma cells. KOM-14 was more potent than NKO-09 in the antimelanoma activity, and its effect was superior than that of 5-fluorouracil. From these findings, it is suggested that NKO-09 and KOM-14 can be used as an efficacious depigmentor and antimelanoma drug, respectively.

Animals↗
PubMed1998

Septic arthritis of a lumbar facet joint: report of a case with early MRI findings.

A 56-year-old man was hospitalized with a 2-day history of back pain and fever. A magnetic resonance (MR) scan taken on admission showed a facet joint effusion and soft-tissue abnormality posterior to the joint. Follow-up MR imaging confirmed the facet joint destruction and periarticular abscess. A biopsy specimen grew Staphylococcus aureus. MR imaging is helpful in detecting this rare infection in the earliest phase of the disease.

Abscess↗
PubMed1997

MR findings in iliotibial band syndrome.

OBJECTIVE: To elucidate the MR findings in iliotibial band (ITB) syndrome. DESIGN AND PATIENTS: The subjects comprised four patients (five knees) with lateral knee pain: two athletes and two non-athletes. One non-athlete was engaged in work requiring repetitive knee movement, and the other suffered from Cushing syndrome and had bilateral abnormalities. All patients were suspected of having a lateral meniscal tear prior to MR examination, but physical examination following provisional MR diagnosis warranted the final diagnosis. MR studies included fast spin echo sagittal imaging, fat-saturated fast spin echo proton density coronal imaging, and T2* radial imaging. Twelve normal volunteers were examined. RESULTS AND CONCLUSION: Fat-saturated coronal imaging demonstrated an ill-defined, high-intensity area deep to the ITB. T2* radial imaging showed an identical, but less conspicuous, abnormality. The MR finding suggested soft tissue inflammation and/or edema rather than focal fluid collection in the bursae. The signal alteration predominated in the region beneath the posterior fibers of the ITB, thus supporting the current opinion that the posterior fibers of the ITB are tighter against the lateral femoral epicondyle than the anterior fibers. The ITB itself did not show any signal alteration or increased thickness.

Adolescent↗
PubMed1997

Epithelioid sarcoma with unusual radiological findings.

The case of a patient with epithelioid sarcoma in the right arm is reported. The diagnosis was delayed because of misinterpretation arising from complexity in the MR findings, including a honeycomb pattern in the subcutaneous fat simulating lymphedema, and an intramuscular diffuse high signal intensity on T2-weighted images without a discrete mass lesion. The histological findings revealed that the diffuse muscular abnormality mainly resulted from denervation of the muscles due to perineural invasion by the tumor, and subcutaneous edema from lymphedema secondary to lymphatic tumor spread concurrent with lymphatic fibrosis. Multiple foci of cortical erosions in the humerus, a rare manifestation of this tumor, were detected 6 months later.

Arm↗
PubMed1997

Malignant fibrous histiocytoma arising from a calcifying enchondroma--a case report.

A man, 79 years of age, developed a malignant fibrous histiocytoma which arose in relation to a calcifying enchondroma of the distal femur. Radiographs showed a fracture through an intensely calcified bony tumour with no bony destruction. The clinical diagnosis was a dedifferentiated chondrosarcoma. Histology showed an anaplastic sarcoma with calcified tissue showing extensive areas of necrosis and degeneration. No chondrosarcomatous foci were found.

Aged↗
PubMed1997

Generalized metaphyseal modification with cone-shaped epiphyses following long-term administration of 13-cis-retinoic acid.

UNLABELLED: We report on a 6-year-old girl with short stature which developed following the administration of 13-cis-retinoic acid (a synthetic derivative of vitamin A or retinoid) for 40 months as adjunct chemotherapy for neuroblastoma. Radiographic examination suggested osteophyte formation in the cervical spine, which is the most common skeletal manifestation of retinoid toxicity [10, 11]. In addition, severe metaphyseal cupping with a cone-shaped epiphysis primarily affecting rapidly growing long bones was found, which represented impaired enchondral ossification. This epi-metaphyseal alteration, though unusually severe, was reminiscent of the premature epiphyseal closure which has been described as an adverse effect of 13-cis-retinoic acid [10-12]. Other minor skeletal changes included posterior scalloping of the vertebral bodies and increased interpediculate distances, which were related to a widened spinal canal found on CT. A literature search disclosed several primary skeletal dysplasias with superficial radiological similarities to those of the present patient. However, these entities showed significant clinical and radiological differences from our patient. CONCLUSION: The precise cause of the generalized skeletal alteration in the present patient remained unknown, but it conceivably resulted from the administration of 13-cis-retinoic acid.

Child↗
PubMed1997

Characterization of serotype II polysaccharide antigen of group E streptococci using a monoclonal antibody.

A Monoclonal antibody (MAb II-T) specific for serotypes II and V Group E streptococci (GES) was prepared by fusing myeloma cells with spleen cells of mice immunized with whole cells of a serotype II strain. MAb II-T reacted in an enzyme immunoassay (EIA) with whole cells of both serotypes and reacted in gel diffusion test with autoclaved-saline extraction of serotypes II and V. The extract was purified by DEAE-Sephadex A-25, followed by treatment with proteinase K, and further by chromatography with a Sephadex G-200 column. The purified polysaccharide (PS) antigen contained 98.6% carbohydrate and 1.4% protein, but no detectable phosphorus. In hapten inhibition tests using various sugars, D-mannosamine markedly inhibited the precipitin reaction. These results indicated that the antigenic determinant might have a structure similar to D-mannosamine.

Antibodies, Bacterial↗
PubMed1997

Quantitation by enzyme immunoassay of spirosin from Lactobacillus reuteri and Escherichia coli.

Three EIA methods (Direct, Indirect and Sandwich EIA) were studied to quantify spirosin in Lactobacillus reuteri and Escherichia coli cultured under various conditions in an attempt to get some insight into the function of spirosome. Both Direct and Indirect EIA were suited well for the quantitation of L. reuteri spirosin while Direct EIA was appropriate for spirosin of E. coli. Sandwich EIA could not be applied successfully in either case. By use of these methods, the amounts of spirosin produced by E. coli were determined to be 1.4, 36.2 and 46.5 micrograms per mg protein of the cell lysate under aerobic, standing and anaerobic culture conditions, respectively. Since the production profile of spirosin coincided entirely with that of alcohol dehydrogenase, these findings supported the identity of spirosin to alcohol dehydrogenase in E. coli. In the same way, L. reuteri spirosin was quantified to be 73.5 and 65.4 micrograms/ mg protein of the lysate in standing and anaerobic culture, respectively. The production pattern of spirosin did not parallel that of alcohol dehydrogenase among three strains of L. reuteri, suggesting that spirosin might not be identical to alcohol dehydrogenase.

Aerobiosis↗
PubMed1997

Syntheses and antifungal activity of dl-griseofulvin and its congeners. III.

Several congeners (1b-g), with novel substituents on the benzene ring of griseofulvin, were prepared by the application of a synthetic method developed by us. Antifungal activity of these congeners decreased in order of dl-griseofulvin (1a) = 1d > 1b, c >> 1e-f (inactive). The relationship between the antifungal activity and the position or kind of substituents on the benzene ring of griseofulvin is discussed.

Antifungal Agents↗
PubMed1997

Synthesis and antitumor activity of fused quinoline derivatives. V. Methylindolo[3,2-b]quinolines.

Indolo[3,2-b]quinoline derivatives (1b-i) with a methyl group at each possible position have been synthesized. The 1-methyl (1b) and 9-methyl (1i) derivatives were inactive, but the 3-methyl (1d), 4-methyl (1e), and 6-methyl (1f) derivatives exhibited high treatment/control (T/C) value and cure rates against leukemia P388 in mice. These results indicated that modification of indolo[3,2-b]quinoline derivatives at 3, 4, and 6 positions may be useful approach for lead optimization.

Animals↗
PubMed1997

Syntheses and antifungal activity of dl-griseofulvin and its congeners. II.

Griseofulvin derivatives, dl-6'-demethyl-6'-ethylgriseofulvin (dl-5) and dl-6'demethyl-6'phenylgriseofulvin (dl-6) were prepared by application of a synthetic method developed by us. Antifungal activity of these derivatives decreased in the order of dl-griseofulvin (dl-1) >> dl-6(inactive). The reaction of these derivatives with ethanethiol gave two types of compounds, 2'-(ethylthio)griseofulvin (15) and 4'-(ethylthio)isogriseofulvin (16). The relationship between the ratios of isolated yield of 15 and 16 and antifungal the activity of griseofulvin derivatives is discussed.

Antifungal Agents↗