Biomedical subjects

M Yoshioka

Publications and source records attributed to M Yoshioka.

At least 181 records · Page 10Linked to original sources

PubMed1997

Development of enzyme immunoassay of 2'-deoxycytidine.

In order to study 2'-deoxycytidine (2'-dCyd) as a possible prognostic marker in cancer chemotherapy, an enzyme immunoassay (EIA) was developed. 2'-dCyd as a hapten was succinylated and two omicron-monosuccinyl-2'-dCyd's were purified by high performance liquid chromatography and identified by mass spectrometry and 1H-NMR. Two antigens were prepared by conjugating two omicron-succinyl derivatives with keyhole limpet hemocyanin (KLH) as a carrier. Both antigen produced specific antibodies to 2'dCyd in BALD/c mice. The spleen cells of one mouse immunized with 5'-omicron-succinyl-2'-dCyd-KLH were hybridized with myeloma cells. One monoclone selected produced a specific antibody. A convenient EIA was attained by using the monoclonal antibody.

Animals↗

PubMed1997

Flow injection analysis for measurement of activity of matrix metalloproteinase-7 (MMP-7).

A simple and convenient method for measuring the activity of a recombinant human matrix metalloproteinase 7 (MMP-7, matrilysin) was developed by flow injection analysis (FIA). For this method, purified recombinant MMP-7 zymogen expressed in E. coli and the substrate peptide (MOCAc-Pro-Leu-Gly-Leu-A2pr(DNP)-Ala-Arg-NH2) were used. Following the incubation of substrate peptide with activated r-proMMP-7, the resulting fluorescent product peptide (MOCAc-Pro-Leu-GLY) was monitored with a fluorescence detector (lambda ex 328 mm, lambda em 393 mm) without chromatographic separation. In this FIA system, the analysis time is 2 min and the standard curve is linear from 5 to 100 pmol of the product peptide injected. In order to use this FIA system as a method for screening inhibitors against MMP-7, the effects of CaCl2, EDTA and of the tissue inhibitor of metalloproteinase-1, and -2, were tested. A synthetic PRCGXPD-containing peptide (BS-10) was also observed to inhibit MMP-7 activity, with an IC50 value of 104 microM. Thus, it was concluded that the activity of r-MMP-7 can be reliably measured by the proposed system. Furthermore, to confirm the utility of this FIA system as a screening method, the inhibitory activity of the MMP-related substance in Joro spider (Nephilia clavata) venom was measured by this method. This inhibitory activity was observed in an extract of a venom diluted 1000-fold. Thus, the FIA method is not only simple and quick, but also sensitive enough to screen and analyze the inhibitory properties of a large number of test compounds.

Enzyme Inhibitors↗

PubMed1997

The effects of hyaluronan during the development of osteoarthritis.

Ninety-nine mature New Zealand White (NZW) rabbits underwent unilateral anterior cruciate ligament transection (ACLT) and were divided into three groups. The contralateral non-operated knees served as controls. The first group (SA) received intra-articular injections of 0.3 ml hyaluronan (HA: MW; 8 x 10(5)) beginning 4 weeks after ACLT, once a week for 5 weeks. The second group (SV) was injected with vehicle (carrier of HA) in the same fashion as the SA group. The third group (SN) served as a nontreatment group post ACLT. All animals were killed 9 weeks post-surgery and were assessed by gross morphology, histomorphometry and biochemical analysis. Gross morphologic changes on the femoral cartilage in the SA group were less severe than those in the SV and SN groups. Cartilage thickness, cartilage area, and thickness of synovial lining cell layer histomorphometric parameters were measured, showing a positive effect of HA on the preservation of articular cartilage and synovial tissue. Similarly, the cartilage and synovial tissues from knees injected with HA did not demonstrate significant alterations from contralateral controls as measured by biochemical analysis [i.e., water content, pyridinoline concentration, glycosaminoglycan (GAG) content for the cartilage, and DNA concentration for the synovial tissue].

Animals↗

PubMed1997

A methodology for the quantitative assessment of articular cartilage histomorphometry.

OBJECTIVE: Traditionally, histological analysis of cartilage and cartilage repair has been performed qualitatively. While new techniques and grading systems have attempted to improve the quantitative nature of histological assessment, the advent of computer-based analysis systems have enabled development of more quantitative methodologies for cartilage repair. The objective of this study was to develop such a methodology for a more quantitative assessment of cartilage repair using a color-based image analysis system. DESIGN: Repair parameters were defined to describe the degree of cartilage restoration: repair dimensions, degree of attachment, surface roughness and repair location. This technique was experimentally applied to a cartilage repair study using cultured perichondrial cells implanted in a polylactic acid matrix in the rabbit femoral condyle. Specimens were examined and compared with the contralateral normal knee. RESULTS: Results showed increases in cartilage height, repair area, and surface roughness over controls for both 6 and 12 weeks. Surface elevation was significantly decreased at 6 weeks over 12 weeks. The percentage of repair improved between 6 and 12 weeks. Results were compared with a traditional grading system and demonstrated close correlation. Intraobserver and interobserver precision analysis were performed and demonstrated the reproducibility of the quantitative results by and between individuals. CONCLUSIONS: The methodology was deemed successful for a more objective analysis of cartilage with the added advantage of providing measured parameters that can assist in making comparisons between different studies using the same methodology.

Animals↗

PubMed1997

Effects of sorbed water on the crystallization of indomethacin from the amorphous state.

The water sorption isotherm and the crystallization rates for amorphous indomethacin were determined at 30 degrees C as a function of relative humidity (RH), along with the effects of water content on the glass transition temperature (T(g)). Below 43% RH, only the stable gamma crystal form appears, whereas at higher RH, only the metastable alpha crystal form appears. The tendency for the alpha crystals to form at higher RH is consistent with the Ostwald step rule. The crystallization rate of the alpha form continuously increased with increasing RH due to increasing molecular mobility. The crystallization mechanism of the gamma form changed from surface-initiated to bulk-initiated crystallization at 21% RH, and although crystallization rates of the gamma form increased with increasing RH in both cases, they were higher when crystallization was surface-initiated. The complex crystallization behavior of the gamma form is explained by the higher water content and molecular mobility of the surface relative to the bulk and the general effect of water on alpha or gamma crystal form selection as described by the Ostwald step rule.

Absorption↗

PubMed1997

Osteochondral repair using perichondrial cells. A 1-year study in rabbits.

Articular cartilage repair remains a clinical and scientific challenge with increasing interest focused on the transplantation of chondrogenic cells. This study evaluated the repair response during a 1-year period after implantation of allogenic perichondrium cell polylactic acid composite grafts into 3.7 x 5 mm osteochondral defects drilled into the medial femoral condyles of 82 adult New Zealand White rabbits. The repair tissue was evaluated grossly, histologically, histomorphometrically, biochemically, and biomechanically at 6 weeks, 12 weeks, 6 months, and 1 year after implantation. After gross evaluation, cartilaginous material appeared to fill the defect in 70 experimental knees, for an overall repair frequency of 85%. The histomorphometric results and the histologic appearances were variable. None of the specimens were completely normal at 1 year. Only specimens with subchondral bone reformation displayed a definable cartilage appearing surface with chondrocytes surrounded by dense matrix. Subchondral bone reformation was inconsistent, reaching 50% at 1 year. Biochemically, the repair tissue matured during a 1-year period into a hyaline Type II collagen dominant tissue, whereas glycosaminoglycan content remained low at all time periods. The measured compressive properties of the repair tissue at 1 year were not significantly different from those of the contralateral knee that was not surgically treated. The treatment of osteochondral defects in the rabbit knee with allogenic perichondrium cell polylactic acid composite grafts yielded a high percentage of grossly successful repairs that showed inconsistent subchondral bone reformation. These results suggest that healthy subchondral bone is important to articular cartilage repair. They also highlight that a cartilaginous appearing tissue at gross inspection may not represent structurally normal articular cartilage. Continued multidisciplinary studies on the arthroplastic potential of rib perichondrial cells are needed before human studies, which rarely can extend beyond gross assessment of repair tissue appearance can be undertaken.

Animals↗

PubMed1997

Dietary red pepper ingestion increases carbohydrate oxidation at rest and during exercise in runners.

The effects of dietary hot red pepper on energy metabolism at rest and during exercise were examined in long distance male runners 18-23 yr of age. A standardized meal was given on the evening prior to the experiment. The subjects had a meal (2720 kJ) with or without 10 g of hot red pepper for breakfast. During rest (2.5 h after meal) and exercise (pedaling for 1 h at 150 W, about 60% VO2max, using cycling ergometry), expired gasses and venous blood were collected. The meal with hot red pepper significantly elevated respiratory quotient and blood lactate levels at rest and during exercise. Oxygen consumption at rest was slightly but nonsignificantly higher in the hot red pepper meal at 30 min after the meal. Plasma epinephrine and norepinephrine levels were significantly higher in those who had only hot red pepper at 30 min after the meal. These results suggest that hot red pepper ingestion stimulates carbohydrate oxidation at rest and during exercise.

Adolescent↗

PubMed1997

Regional differences in adipose tissue metabolism between sedentary and endurance-trained women.

Subcutaneous (subc) abdominal and femoral adipose tissue metabolism was studied in sedentary and endurance-trained premenopausal women. Both fat cell weight and lipoprotein lipase (LPL) activity were lower in the subc abdominal depot of trained women compared with controls. Epinephrine- and isoproterenol-stimulated lipolytic responses, as well as the beta-adrenergic sensitivity of subc abdominal adipocytes, were higher in trained than in sedentary women, whereas both the antilipolytic effect of brimonidine (UK-14304) and the alpha 2-adrenoceptor sensitivity were lower in endurance-trained than in sedentary subjects. Maximal lipolysis in the presence of postadrenoceptor agents was also enhanced in subc abdominal adipose cells of trained women compared with sedentary controls. Negative relationships were found between maximal lipolytic responses of subc abdominal fat cells to catecholamines or to postreceptor agents and body fatness as well as abdominal fat distribution indexes. It is concluded that 1) endurance-trained women are characterized by a preferential lipid mobilization from the subc abdominal fat depot, and 2) differences in the metabolic characteristics of subc abdominal adipocytes between trained and sedentary women may involve changes in both LPL activity and the lipolytic cascade that include modifications at receptor and postreceptor levels. However, these alterations appear to be largely resulting from the reduced adipose cell size rather than from exercise training per se.

Abdomen↗

PubMed1997

Properties of calcium spikes revealed during GABAA receptor antagonism in hippocampal CA1 neurons from guinea pigs.

Properties of calcium spikes revealed during GABAA receptor antagonism in hippocampal CA1 neurons from guinea pigs. J. Neurophysiol. 78: 2269-2279, 1997. Intracellular electrical responses and changes in intracellular calcium concentration ([Ca2+]i) in response to activation of synaptic inputs and to DC injections were recorded simultaneously from CA1 pyramidal neurons (n = 42) in guinea pig hippocampal slices. In the presence of the gamma-aminobutyric acid-A (GABAA) receptor antagonists, bicuculline (mu M) and picrotoxin (10 mu M, broad (>20 ms) all-or-none spikes were induced by activation of synaptic inputs (20 pulses, 30 Hz) and were accompanied by a simultaneous rapid and large rise in [Ca2+]i (34 of 34 cells). By contrast, direct depolarizing current (0.7 nA, 1 s) induced spikes having short duration, during which time the spike firing pattern was observed not to be significantly affected. When Na+ channels were blocked by QX-314 applied intracellularly through the recording microelectrode in the presence of GABAA receptor antagonists, broad spikes were frequently generated by activation of synaptic inputs (32 of 33 cells). These broad spikes were blocked by Cd2+ (200 mu M) or in Ca2+-free medium (6 of 6 cells) but were resistant to either tetrodotoxin (TTX; 1 micro M; 6 of 6 cells) or QX-314, whereas short-duration spikes were blocked by both TTX and QX-314. Based on these findings we conclude that broad and short-duration spikes are Ca2+ and Na+ spikes, respectively. To investigate the properties of the Ca2+ spikes, antagonists of a voltage-operated Ca2+ channel were applied to the evoked responses. Nifedipine (30 mu M), a L-type Ca2+ channel blocker, suppressed the generation of Ca2+ spikes, whereas Ni2+ (100 mu M), the T- and R-type Ca2+ channel blocker, and omega-agatoxin-IVA (omega-Aga-IVA, 60 nM), a P-type Ca2+ channel blocker, had little effect on the generation of Ca2+ spikes. Nifedipine suppressed the rise in [Ca2+]i induced by synaptic inputs up to 26% of the control in the soma and 18-32% in the dendrites (n = 5), respectively, whereas Ni2+ suppressed the rise by 12-27% (n = 5) in both soma and dendrites. omega-Aga-IVA showed little effect (less than a 10% change; n = 7). These results suggest that the GABAA inhibitory system tonically suppresses dendritic Ca2+ spikes, and the L-type Ca2+ channel plays a major role in the generation of Ca2+ spikes and in Ca2+ influx.

Animals↗

PubMed1997

Fluorometric determination of 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline in biological materials by HPLC.

In the belief that endogenous 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline (DA-Fp) could be a potential marker involved in the etiology of various diseases such as Parkinsonism, we attempted to develop a fluorescence method for DA-Fp. It was synthesized by condensation of dopamine with formaldehyde according to an established method. Periodate was identified by screening from various oxidation reagents as a fluorescence reagent to DA-Fp. Optimal reaction conditions were obtained with 0.25 mM NaIO4 in 0.1 M phosphate buffer (pH 8.0) at 37 degrees C for 15 min. The fluorescence spectrum of the derivative showed that we had found a new reaction specific for DA-Fp. This reaction was coupled on-line to high performance liquid chromatography (HPLC), which enabled us to achieve a highly sensitive method for determining DA-Fp. A working curve was linear from 2 to 800 pmol of DA-Fp per injection. To determine DA-Fp in biological materials, the pretreatment before HPLC was optimized by hydrolysis of its conjugate and suppression of the artifact with l-phenylephrine. Urinary excretion of DA-Fp in men was measured by this new present method. The urinary excretion of endogenous DA-Fp increased in a rabbit given L-DOPA. The DA-Fp concentration was determined in rat brain. The significance of DA-Fp in these biological materials is discussed and evaluated. We conclude that the present method will be useful for studying tetrahydroisoquinolines involved in many diseases.

Animals↗

PubMed1997

A novel bufadienolide, marinosin, in the skin of the giant toad, Bufo marinus.

We have identified a novel cardiac steroid, 11,19-epoxy-19-methoxytelocinobufagin, named marinosin (1), in the skin of the toad, Bufo marinus (L.) Schneider. The treatment of compound 1 with 50% CH3CN containing 0.1% trifluoroacetic acid yielded a 11 alpha-hydroxyhellebrigenin (2), which has not previously been isolated from animals or plants. The structures of both compounds were established from spectral data obtained by NMR and MS, which were compared with those of a reference bufadienolide, 11 alpha-hydroxytelocinobufagin. Compounds 1 and 2 have A/B cis and C/D cis configuration, which is characteristic of bufadienolides such as bufalin and marinobufagin. However, the stereo-structure of compound 1 was characterized by a boat form of the B ring, which is different from the chair form in typical bufadienolides such as compound 2. Compounds 1 and 2 both exhibited activity, as demonstrated by inhibition of Na+, K(+)-ATPase enzymatic activity and by inhibition of the binding of [3H]ouabain to Na+, K(+)-ATPase; however, marinosin (1) was as less effective inhibitor than 2, 11 alpha-hydroxyhellebrigenin. We have identified compound 2 in toad venom, but not in the skin.

Animals↗

PubMed1997

[Diversity of joro spider toxins].

In a study to solve a mystery of venom toxicity of the joro spider, Nephila clavata, we purified and identified novel spider toxins such as clavamine, spidamine and joramine. Chemical analyses, bioassays and physical analyses were specifically elaborated in these procedures. The structure-activity relationship of the spider toxins was discussed biologically and chemically in comparison with the other spider toxins. We considered that the diversity of the joro spider toxins by reserving 2,4-dihydroxyphenylacetyl-L-asparaginylcadaverine as a common moiety gave rise to an important insight into not only the toxic reaction, but also the ontology.

Animals↗

PubMed1997

[Effect of proteases from Porphyromonas gingivalis on adhesion molecules of human periodontal ligament fibroblast cells].

Porphyromonas gingivalis (P. gingivalis) has been implicated as an important pathogen in periodontal diseases, and its protease (Arg-gingipain) is one of the most important disease-causing factors. We have examined the effect of Arg-gingipain on the cell adhesion molecules of human periodontal ligament fibroblasts (HPLF). The Arg-gingipain was purified from the culture supernatant of P. gingivalis. Confluent monolayer cultures of HPLF were incubated for up to 24 hr with Arg-gingipain. As for the morphological changes, HPLF detached from the dish at 16 hr. The growth rate as evaluated by the MTT assay increased at 12 hr, and then the rate decreased. The cell adhesion molecules (ICAM-1, intercellular adhesion molecule-1; CD54, VCAM-1, vascular cell adhesion molecule-1; CD106, and VLA-4, very late antigen-4; CD49d/cd29) were constitutively expressed on HPLF by flow cytometric analysis. The amounts of fibronectin were increased at 12 hr and then, its production was decreased. The levels of ICAM-1, VCAM-1 and VLA-4 expressions were increased; however, after 16 hr, the levels of expression of all cell adhesion molecules were decreased. Our experiments showed that adhesion decreases as a result of destruction of the extracellular matrix when bacterial protease brings about rapid cell destruction. This may suggest that the increase of expression of cell adhesion molecules is due to a mechanism that compensates for the decreased cellular-extracellular matrix. Alternatively, it may suggest that after the expression is activated, cell adhesion molecules help to increase bacterial adhesion to cells.

Adhesins, Bacterial↗

PubMed1997

A novel locus, Mody4, distal to D7Mit189 on chromosome 7 determines early-onset NIDDM in nonobese C57BL/6 (Akita) mutant mice.

In this article, we report on a nonobese C57BL/6 (B6) mouse model of NIDDM named Akita mouse, characterized by early age onset and autosomal dominant mode of inheritance. At 7 weeks of age, the mean morning blood glucose levels (mmol/l) under ad libitum feeding conditions were significantly higher (P < 0.01, analysis of variance [ANOVA]) in diabetic mice than in unaffected mice: 27.3 +/- 5.3 for diabetic males (n = 50) and 9.3 +/- 1.2 for unaffected males (n = 50); 13.6 +/- 3.8 for diabetic females (n = 50) and 8.7 +/- 1.1 for unaffected females (n = 50), while corresponding immunoreactive insulin levels in plasma were significantly lower in diabetic mice than in unaffected mice. In vitro insulin secretion was also impaired, even at 4 weeks of age. The 50% survival time for male diabetic mice (305 days) was significantly shorter than that of unaffected counterpart mice but not for diabetic females. Obesity did not occur in diabetic mice. Histological examinations of the pancreas in diabetic mice, from 4 to 35 weeks of age, revealed decreases in the numbers of active beta-cells without insulitis. Morphometry demonstrated specific decreases in immunologically detectable insulin density in islets in diabetic mice, even at 4 weeks of age, without changes of relative islet areas. By linkage analysis, a single locus was identified on the basis of 178 N2 mice [(B6 x C3H/He)F1 x B6 and (B6 x C3H/He)F1 x C3H/He]. This locus, which we named Mody4, was mapped to chromosome 7 in a region 2-8 cM distal to D7Mit189 (logarithm of odds [LOD] score = 15.6 and 10.3).

Alanine Transaminase↗

PubMed1997

[Pathogenesis of HIV-1-associated-neurologic diseases].

The neurologic disease most frequently seen during acquired immunodeficiency syndrome (AIDS) is AIDS dementia complex (ADC) or HIV encephalopathy, which is a direct consequence of HIV-1 infection of the central nervous system (CNS). A limited expression of HIV-1 in CNS and peripheral nervous system (PNS) tissue of AIDS patients in contrast to widespread functional and pathologic abnormalities suggests indirect or immunopathogenetic mechanisms of ADC and HIV-1-associated predominantly sensory neuropathy. Proposed mechanisms include injury of oligodendrocytes by tumor necrosis factor-alpha (TNF-alpha) released from macrophages, calcium dependent excitoneurotoxicity induced by gp120 HIV-1 envelope protein, N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity by quinolinic acid, cell injury by HIV-1-specific cytotoxic T cells, and apoptosis of oligodendrocytes or neurons. The amplification of cellular activation by cytokine network and cell-to-cell contact between activated macrophages and neural cells by upregulation of adhesion molecules dramatically enhance toxic effect of macrophage products.

AIDS Dementia Complex↗

PubMed1997

Cyclophosphamide increases 5-hydroxytryptamine release from the isolated ileum of the rat.

We recently reported that chronic administration of cyclophosphamide significantly increased urinary 5-hydroxyindole acetic acid (5-HIAA) excretion in rats indicative of a release of 5-hydroxytryptamine (5-HT) from intestinal enterochromaffin (EC) cells. Cyclophosphamide is considered to be an inactive prodrug and require conversion to active emetic metabolities (e.g. phosphoramide mustard) by hepatic metabolism. However the presence of cytochrome P450 in the intestine raises the possibility of cyclophosphamide metabolism in the wall of the intestine, a site which would have considerable significance for 5-HT release and the emetic effects of cyclophosphamide. The aim of this study was to investigate whether cyclophosphamide could induce the release of 5-HT from the isolated ileum and to examine its mechanism of action. Cyclophosphamide (10(-6)M and 10(-7)M) induced a concentration dependent increase of 5-HT from rat isolated ileum. This cyclophosphamide-induced 5-HT release was significantly reduced by granisetron (10(-6)M and 10(-7)M) or atropine (10(-7)M and 10(-6)M). Tetrodotoxin (10(-6)M completely inhibited the increased 5-HT release induced by cyclophosphamide. These results suggest that cyclophosphamide has the capacity to induce 5-HT release via activation of enteric cholinergic neurons. In addition the in vitro study demonstrate for the first time that cyclophosphamide may be activated to emetic metabolites at extra-hepatic sites (e.g. intestine) and that conversion at these sites could contribute to the mechanism of cyclophosphamide induced emesis.

Animals↗

PubMed1996

A tumor preventive effect of dietary restriction is antagonized by a high housing temperature through deprivation of torpor.

Energy restriction (ER) has proven to be the only effective means of retarding aging in mice. The mechanisms of multiplicity of effects of ER on aging remain, however, fragmentary. ER induces daily torpor, the induction of which is reduced by increasing the ambient temperature to 30 degrees C. The effects of preventing hypothermia in ER animals were studied in terms of the expected consequences of ER on survival, disease pattern and a number of physiological parameters in autoimmune prone MRL/lpr mice and lymphoma prone C57BL, 6 mice. The results demonstrate that torpor plays a crucial role in the prevention of lymphoma development but does not have an affect on other aspects of ER, such as prevention of autoimmune diseases.

Aging↗

PubMed1996

Effect of conditioned fear stress on dopamine release in the rat prefrontal cortex.

The effects of conditioned fear stress (CFS) on dopamine release in the medial prefrontal cortex were studied by in vivo microdialysis in the rat. CFS (exposure to an environment in which foot-shock had been delivered previously) induced a marked suppression of motility, i.e., freezing behavior. Extracellular concentrations of dopamine in the medial prefrontal cortex were increased by CFS. The increase of dopamine returned to the pretreatment levels when rats were returned to the home cages. Diazepam (0.5 mg/kg, i.p.) suppressed both the CFS-induced freezing behavior and extracellular dopamine levels in the medial prefrontal cortex. These findings suggest that anxiety and dopamine release in the prefrontal cortex might be related.

Animals↗