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Biomedical subjects

K Shirai

Publications and source records attributed to K Shirai.

At least 55 records · Page 3Linked to original sources
PubMed2000

Improvement of the material property of shark type I collagen by composing with pig type I collagen.

Fibril reconstruction process, that is, the nucleation and growth of mixed type I collagen fibril of shark and pig, progressed faster than that of the individual collagen species of shark or pig. The reconstructed mixed collagen fibril had a greater resistance to return to the solution or to melt into gelatin in comparison with the counterpart consisting solely of shark collagen. The denaturation temperature of the mixed collagen gel was about 10 degrees C higher than that of shark, and about 5 degrees C lower than that of pig. By scanning electron microscopy, the diameter of mixed collagen fibril showed an intermediate range between shark and pig collagen fibril. The breaking strength of the mixed collagen gel was tougher than that of pig, but weaker than that of shark. Other physicochemical properties of the mixed type I collagen gel were observed to be at intermediate positions between those of shark and pig type I collagen gels.

Animals↗
PubMed2000

Preparation and dynamic viscoelasticity characterization of alkali-solubilized collagen from shark skin.

Alkali-solubilized collagens, prepared by alkali-acid extraction and alkali direct extraction (abbreviated AASC and ALSC, respectively), were characterized by dynamic viscoelastic measurement of collagen solution (10 mg/mL). The optimum preparative conditions in terms of yield and polypeptide size are as follows: for the alkali-acid extraction, a pretreatment with 0.5 or 1 M NaOH containing 15% Na(2)SO(4) within 5 days at 20 degrees C followed by the subsequent acid extraction, and for the alkaline direct extraction, a treatment with 0.5 M NaOH containing 10% NaCl at 4 degrees C for 20-30 days. A major portion of the polypeptide sizes of AASC and ALSC is composed of alpha chains (alpha1 and alpha2). Dynamic viscoelasticity of collagen solution was measured as a function of temperature. AASC showed a greater contribution of elastic behavior rather than viscous behavior. On the contrary, ALSC exhibits a stronger viscous behavior than elastic behavior.

Animals↗
PubMed2000

The physicochemical property of shark type I collagen gel and membrane.

The physicochemical properties of shark type I collagen gel and membrane were not same as those of pig type I collagen. The denaturation temperature of shark collagen gel was about 15 degrees C lower. According to scanning electronic micrography, the diameter of shark collagen fibril was relatively thin and more homogeneous. The breaking strength of shark collagen gel was greater, and shark collagen membrane had a greater mechanical strength and a higher water vapor sorption.

Animals↗
PubMed2000

Physical properties of shark gelatin compared with pig gelatin.

Physical properties of shark gelatin were examined during gel formation and postgelation in comparison with pig gelatin. Samples with various concentrations and pH values were evaluated by breaking strength, dynamic viscoelasticity, and dynamic light scattering. Sol-gel and gel-sol transition temperatures for shark gelatin were remarkably lower than those for pig gelatin. Shark gelatin gel shows a narrower pH range to form a stable gel compared with pig gelatin. Melting enthalpy of shark gelatin gel was greater than that of pig gelatin gel, and G' of shark gelatin gel changed more extensively with rising temperature in comparison with pig gelatin gel. It is concluded that shark gelatin has different characteristics from pig gelatin not only for gel characteristics but also for the solution property.

Animals↗
PubMed2000

High cardiac angiotensin-II-forming activity in infarcted and non-infarcted human myocardium.

The aims of this study were to compare human cardiac angiotensin-II-forming activity (AIIFA) between the intact area of control autopsy hearts without cardiac disease (n = 10) and the infarcted or non-infarcted area of autopsy hearts with myocardial infarction (MI, n = 7) and to determine responsible angiotensin-II-forming enzymes. Cardiac total and chymase-dependent AIIFAs were significantly higher in the infarcted and non-infarcted myocardium than those in non-MI heart, while angiotensin-converting enzyme-dependent AIIFA increased only in the infarcted myocardium. The density of chymase antibody-positive mast cells in the non-infarcted area of MI heart correlated positively with total or chymase-dependent AIIFA. Augmented AIIFA was also detected in the left atrium of post-MI hearts. Our results indicated that cardiac angiotensin II formation could be activated in the infarcted as well as in non-infarcted myocardium of the post-MI human heart.

Adult↗
PubMed2000

Deep venous thrombosis and pulmonary thromboembolism associated with a huge uterine myoma--a case report.

A 51-year-old woman with a large uterine myoma suffered from acute pulmonary thromboembolism. Venography revealed thrombosis in the right common iliac vein and almost complete obstruction of the left common iliac vein. The ascending lumbar vein showed collateral drainage. Treatment was initiated with continuous intravenous heparin sodium, and a Greenfield filter was inserted to prevent the extension of the pulmonary embolism during and after hysterectomy. After a total hysterectomy, venography revealed restoration of patency in the bilateral common iliac veins, and no flow was seen in the ascending lumbar vein. Thorough clinical examinations failed to identify any other prothrombotic conditions. These results suggest that a large uterine myoma compressed veins in the pelvis, and the resulting impaired blood flow caused deep venous thrombosis and pulmonary thromboembolism.

Female↗
PubMed2000

Affinity of placental decorin for collagen.

Decorin was isolated from 7 M urea extract of bovine placental cotyledons by ion-exchange and hydrophobic chromatography. Decorin and its core protein showed a broad band at about 115 kDa and a single band at 47 kDa, respectively by SDS-PAGE. Anti-decorin core protein antiserum from pig skin was reacted with placental decorin and its core protein in western blotting. The NH2-terminal amino acid sequence of core protein from placental cotyledons was not different from that of core protein from skin and bone. Glycosaminoglycan of decorin was identified as dermatan sulfate by electrophoresis on a cellulose-acetate membrane and chondroitinase digestivity. Decorin bound to collagen in the order for type III, I, and V.

Amino Acid Sequence↗
PubMed2000

A case of hyperreninemic hypertension after extracorporeal shock-wave lithotripsy.

A 53-year-old male was found to have hypertension caused by the significant secretion of renin from an atrophic left kidney. He had undergone extracorporeal shock-wave lithotripsy (ESWL) for left renal lithiasis 11 years previously. A renal dynamic study with 99mTc-diethylenetriaminepentaacetic acid (DTPA) indicated that the rate of renal excretion and uptake was decreased in the left kidney and normal in the right kidney. Renal angiography demonstrated a normal right renal artery and a small but nonstenotic left renal artery. The ratio of PRA in the left renal vein to that in the right renal vein was 1.7. Blood pressure could be lowered to the range of 140-150/80-90 mmHg with imidapril, an ACE inhibitor. ESWL may cause hypertension via the well-known Page kidney effect. In this case, the kidney, atrophic probably due to ESWL, released a significant amount of renin.

Angiography, Digital Subtraction↗
PubMed1999

Hyperinsulinemic hypoalphalipoproteinemia as a new indicator for coronary heart disease.

OBJECTIVES: The purpose of this study was to investigate the association among insulin resistance, high density lipoprotein cholesterol (HDL-C) and coronary heart disease (CHD), and to test the hypothesis that HDL-C may ameliorate the adverse effects of insulin. BACKGROUND: Serum low HDL-C (hypoalphalipoproteinemia) and hyperinsulinemia are independent predictors for CHD, but a strong negative correlation exists between them, as in patients with syndrome X. METHODS: Fifty-four pairs of cases (M/F: 49/5), defined as patients with angiographically proved CHD, and control subjects (M/F: 49/5) matched with cases with regard to gender and age were included. Insulin resistance was assessed by the homeostasis model assessment (HOMA). RESULTS: Cases had increased HOMA insulin resistance and lower serum levels of HDL-C than controls. A receiver operating characteristic (ROC) curve analysis indicated that HDL-C and insulin resistance were significant discriminators of CHD (area under ROC curve: 0.72 and 0.69, respectively). The interaction between HDL-C and the association of insulin resistance with CHD was significant: subjects with hyperinsulinemia and high HDL-C had no increased risk of CHD. Multivariate conditional logistic regression analysis showed that hyperinsulinemic hypoalphalipoproteinemia was a stronger indicator for CHD than either HDL-C or insulin resistance alone (-2 log likelihood: 19.0 vs. 12.6 or 15.7). CONCLUSIONS: Hyperinsulinemic hypoalphalipoproteinemia was a more potent indicator for CHD than either insulin resistance or low serum HDL-C levels alone, and the adverse effects of hyperinsulinemia seem to be ameliorated by high HDL-C levels.

Aged↗
PubMed1999

A convenient method for synthesis of enantiomerically enriched methylphenidate from N-methoxycarbonylpiperidine.

[formula: see text] This report describes a new method to prepare optically active methylphenidate starting from piperidine. The method consists of a transformation of N-methoxycarbonylpiperidine to the corresponding alpha-methoxylated carbamate I by utilizing electrochemical oxidation followed by the coupling reaction with optically active Evans imides II to produce optically active methylphenidate derivatives III with high stereoselectivities, threo-(2R,2'R)-Methylphenidate (IV; Ar = Ph; Ritalin) was easily prepared from III in three steps.

Adrenergic Agents↗
PubMed1999

Structure and expression properties of the endo-beta-1,4-glucanase A gene from the filamentous fungus Aspergillus nidulans.

Endo-beta-1,4-glucanase A (EG A) of Aspergillus nidulans was purified to homogeneity, and its genomic gene (eglA) was cloned based on partial amino acid sequences of the purified enzyme and sequenced. The eglA gene comprised 1228 bp with four putative introns and encoded a polypeptide of 326 amino acids bearing high homology to the family A cellulases. The eglA promoter activity in A. nidulans was examined using the A. oryzae Taka-amylase A gene as a reporter. Expression of the reporter gene was induced by carboxymethylcellulose and cellobiose, and repressed by glucose, galactose, mannose, xylose, sorbitol, glycerol and succinate. Lactose neither induced nor repressed the expression.

Amino Acid Sequence↗
PubMed1999

Preheparin serum lipoprotein lipase mass level: the effects of age, gender, and types of hyperlipidemias.

To clarify the factors regulating preheparin serum lipoprotein lipase mass (preheparin LPL mass), the correlations between preheparin LPL mass and age, gender and types of hyperlipidemias were investigated in 377 persons who underwent annual health examinations. Preheparin LPL mass level did not significantly differ in individuals from 19 to 70 years old, for both men and women. Preheparin LPL mass level correlated negatively with triglyceride (TG), positively with high density lipoprotein-cholesterol (HDL-C), and not at all with total cholesterol (TC) or low density lipoprotein-cholesterol (LDL-C). Preheparin LPL mass levels were apparently higher in women than in men, but when serum lipid levels were adjusted, preheparin LPL mass levels were identical. In type IV and IIb hyperlipidemia, preheparin LPL mass levels were lower than in type IIa patients and in normals. Remnant positive individuals had lower levels of preheparin LPL mass than the negative individuals. In conclusion, preheparin LPL mass levels were not affected by aging and gender, but were lower in the conditions in which TG catabolism was disturbed, indicating that preheparin LPL mass might reflect somewhat the amount of LPL working in the body.

Adult↗
PubMed1999

Vascular smooth muscle cell outgrowth, proliferation, and apoptosis in young and old rats.

We attempted to identify the effects of aging on the response of vascular smooth muscle cells (VSMCs) to injury. Rat aortas were injured by ballooning, and cell outgrowth of the aortic explants, as well as cell proliferation and apoptosis induced by 7-ketocholesterol in the culture system were compared in young (6-7 weeks) and old (40-50 weeks) rats. Explant outgrowth in uninjured rats did not differ between young and old rats. However, 14 days after balloon injury, the number of explants with outgrowth increased by a factor of four (P<0.01) in young rats, while that of the old rats did not change. Cell proliferation in cultured VSMCs also did not differ between young and old uninjured rats, but, in the injured group, proliferation doubled in young rats (P<0.01), but did not change in the older group. The rate of unadhered cells in the presence of 7-ketocholesterol (30 microM) did not differ between young and old uninjured rats. In the injured rats, however, that of young rats was lower (P<0.01) while that of older rats was higher (P<0.01). The extent of DNA fragmentation (%) after the addition of 7-ketocholesterol (30 microM) did not differ between young and old uninjured rats. In the injured groups, DNA fragmentation was lower in the young rats (P<0.01), and higher in the old ones (P<0.01), when compared to their respective controls. These results indicate that the VSMC injury responses of cell outgrowth and proliferation were more pronounced in the young, and that 7-ketocholesterol-induced apoptosis was more extensive in old rats.

Aging↗
PubMed1999

The effect of insulin sensitizer, troglitazone, on lipoprotein lipase mass in preheparin serum.

Lipoprotein lipase mass exists in preheparin serum, even though the activity is scarcely found. The implication of this is unclear. We studied the effect of an insulin sensitizer, troglitazone, on this preheparin serum lipoprotein lipase mass (preheparin LPL mass) in non-insulin-dependent diabetes mellitus (NIDDM) patients as well as on serum lipid levels and low density lipoproteins (LDL) particle size. Thirty-one NIDDM patients with poor control were administered troglitazone 400 mg/day. Hemoglobin A1c had significantly decreased (13%, P < 0.001) 2 months later. Preheparin LPL mass had gradually increased and a 69% increase (P<0.01) was observed 4 months later. Triglyceride significantly decreased (23%, P < 0.01) and high density lipoprotein-cholesterol increased (10%, P < 0.01), whereas total cholesterol and LDL levels did not change 4 months later. The size of LDL increased significantly (P < 0.01). These results were consistent with the idea that preheparin LPL mass might be relating to the insulin sensitivity enhanced by troglitazone, as well as LDL particle size.

Adult↗
PubMed1999

Development of intraepithelial T lymphocytes in the intestine of irradiated SCID mice by adult liver hematopoietic stem cells from normal mice.

BACKGROUND/AIMS: We recently reported the adult mouse liver to contain c-kit+ stem cells that can give rise to multilineage leukocytes. This study was designed to determine whether or not adult mouse liver stem cells can generate intraepithelial T cells in the intestine as well as to examine the possibility that adult liver c-kit+ stem cells originate from the fetal liver. METHODS: Adult liver mononuclear cells, bone marrow (BM) cells, liver c-kit+ cells or bone BM c-kit+ cells of BALB/c mice were i.v. transferred into 4 Gy irradiated CB17/-SCID mice. In other experiments, fetal liver cells from Ly5.1 C57BL/6 mice and T cell depleted adult BM cells from Ly5.2 C57BL/6 mice were simultaneously transferred into irradiated C57BL/6 SCID mice (Ly5.2). At 1 to 8 weeks after cell transfer, the SCID mice were examined. RESULTS: Not only BM cells and BM c-kit+ cells but also liver mononuclear cells and liver c-kit+ cells reconstituted gamma delta T cells, CD4+ CD8+ double-positive T cells and CD8 alpha+beta- T cells of intestinal intraepithelial lymphocytes of SCID mice. Injection of a mixture of fetal liver cells from Ly5.1 C57BL/6 mice and adult BM cells from Ly5.2 C57BL/6 mice into Ly5.2 C57BL/6 SCID mice induced both Ly5.1 and Ly5.2 T cells, while also generating c-kit+ cells of both Ly5.1 and Ly5.2 origins in the liver. CONCLUSIONS: Adult mouse liver stem cells were able to generate intestinal intraepithelial T cells of the SCID mice, and it is thus suggested that some adult liver stem cells may indeed be derived from the fetal liver.

Animals↗
PubMed1999

Angiotensin I converting enzyme gene polymorphism and insulin resistance in patients with angina pectoris.

The association between insertion/deletion polymorphism of the angiotensin I converting enzyme (ACE) gene and insulin resistance (IR) was investigated in 64 consecutive patients (F/M: 11/53) with angina pectoris without clinically manifest diabetes mellitus who underwent diagnostic coronary angiography. The observed frequency distribution of ACE genotypes did not deviate from that predicted from the Hardy-Weinberg equilibrium in this group. Patients with the ACE-ID genotype had significantly lower IR, as assessed by an oral glucose tolerance test (OGTT) and by homeostatic model assessment (HOMA), compared to those with the ACE-II genotype, as assessed by a multiple comparison analysis. Patients were divided into two groups with low and high HOMA-IR, and the I allele was seen more frequently in the high HOMA-IR group than in the low HOMA-IR group (0.62 v 0.47, respectively, by chi2 test, P < .05). Logistic regression analysis showed that the odds ratio for insulin resistance in patients with the II genotype, compared to those with the ID and DD-genotypes (assuming that the I allele has a recessive effect), was 4.0 (95% confidence interval, 1.2 to 16.5; P = .037), after adjusting for the presence of significant coronary atherosclerosis. In conclusion, the D allele was not associated with higher insulin resistance in patients with angina pectoris; that is, patients with the ID and DD genotypes were associated with a significantly lower risk of insulin resistance, compared to those with the II genotype.

Aged↗
PubMed1999

Effect of filler content and size to properties of composite resins on microwave curing.

The effect of filler content and size to property of composite resin using high purity spherical silica particles on microwave curing was examined by mechanical means and electron microscope observation to develop microwave-curing composite resin inlay. Increasing filler content in three kinds of filler particles (0.45, 0.96 and 1.46 microm) resulted in increasing compressive strength, diametral tensile strength and knoop hardness and indicated the highest values at the operative mixing limit. The effect of particle size was that the mechanical property of the 0.96 microm filled resin was highest, followed by 1.46 microm and 0.45 microm on the same filler content. The 0.96 microm filled resin had about the same knoop hardness on both surfaces of the cured sample, which means that uniform polymerization occurred in the cured sample. With electron microscope observation, the bubbles of about 1.0 microm and the cracks between the fillers and the matrix were observed in each cured resin. This is caused by the excessive absorption of microwave energy in fillers and surface treatment materials of fillers. Therefore, improvement of the composition of filler and surface treatment material of filler are needed, which makes it harder to absorb the microwave energy.

Journal Article↗