Biomedical subjects

M Yamauchi

Publications and source records attributed to M Yamauchi.

At least 91 records · Page 5Linked to original sources

PubMed1999

Left atrial endocardium and prostacyclin.

In patients with rheumatic mitral stenosis, intracardiac thrombi are found mostly, for reasons still unknown, in the left atrium. We compared the release of PGI2 from the endocardium of the left atrium with that of the right ventricle and from the endothelium of the pulmonary arteries. Endocardial endothelial cells (EECs) were isolated from right ventricles (RV) and left atrial appendages (LAA) of porcine hearts, and vascular endothelial cells (VECs) from pulmonary arteries (PA) were obtained from the same animals. Cultured EEC and PA-VEC monolayers were placed in a pressure loading apparatus and incubated for 30 min under various pressures. After incubation, the supernatants were sampled and the 6-keto-PGF1 alpha contents measured. PGI2 release from LAA-EEC was much less than from RV-EEC or from PA-VEC. Moreover, transmural pressure did not enhance PGI2 release from LAA-EEC, although it did from RV-EEC and PA-EEC in a pressure-dependent manner. These results may explain why the left atrium is a common site for intracardiac thrombus formation in patients with mitral valve disease.

6-Ketoprostaglandin F1 alpha↗

PubMed1999

Sequential distribution of keratan sulphate and chondroitin sulphate epitopes during ameloblast differentiation.

Proteoglycans are complex macromolecules containing one or more glycosaminoglycan chains and exhibiting a variety of biological functions in connective tissues. The aim of the present study was to immunolocalize the distribution of keratan sulphate and chondroitin sulphate epitopes during initial enamel formation in order to study temporo-spatial expression patterns of these macromolecules. Third molars of four-months-old pigs were used for immunolocalization of keratan sulphate and chondroitin sulphate epitopes in the developing enamel layer. Tooth organs were prepared for paraffin sections in order to perform indirect immunohistochemistry. The results demonstrated a mutually exclusive positioning between these two epitopes. Keratan sulphate epitopes were observed in pre-secretory pre-ameloblasts and adjacent stratum intermedium while chondroitin sulphate epitopes were demonstrated in secretory ameloblasts and adjacent stratum intermedium. Our findings suggest that proteoglycans containing glycosaminoglycan chains may play a regulatory role during enamel mineralization.

Ameloblasts↗

PubMed1999

Characterization of dermal type I collagen of C3H mouse at different stages of the hair cycle.

Hair follicles develop or regress in accordance with the hair cycle. In this study, we partially characterized fibrillar type I collagen, the predominant component in the dermis, at two stages of the hair cycle: anagen and telogen. Skin samples were obtained from the backs of two groups of 11-week-old C3H mice: one at anagen stage induced by shaving and the other at telogen stage. The amount of neutral salt-soluble (newly synthesized) collagen obtained from anagen skin was about twofold that from telogen skin, while the level of acid-soluble collagen was not significantly different between the two groups. The degree of lysine hydroxylation of pepsinized type I collagen obtained from anagen skin was significantly higher than that in telogen (5.0% higher in alpha1 chain, and 15.6% higher in alpha2 chain). Proline hydroxylation at the anagen stage was also slightly higher than in the telogen stage. Two major collagen cross-links were found in both groups of skin; dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymerodesmosine. The concentration of the latter, a complex tetravalent cross-link, was significantly lower in anagen skin when compared with telogen skin (mean +/- SD 0.64 +/- 0. 07 vs. 0.78 +/- 0.06 mol/mol collagen). The former showed no significant difference between the two groups. In addition, a significant amount of lysyl-aldehyde (a cross-link precursor) was found in anagen (0.16 +/- 0.02 mol/mol collagen), while it was 0.12 mol/mol collagen in telogen. These results indicate that the remodelling of collagen is more active in anagen skin than in telogen, and that characteristic post-translational modifications of dermal collagen seen in anagen may play a part in facilitating an environment around hair follicles for their migration and growth.

Amino Acids↗

PubMed1999

Coactivation of the flexor muscles as a synergist with the extensors during ballistic finger extension movement in trained kendo and karate athletes.

To analyse the effects of ballistic property training on ballistic finger extension movement, surface electromyographic pattern (EMGs) of the finger extensor and flexor muscles and the acceleration signal of the middle finger were recorded in trained kendo and karate athletes, and sedentary non-athletic men. Ballistic finger extension did not show the characteristic triphasic EMG pattern reported in single joint, but a coactivation of flexor and extensor muscles. Reaction time (RT) in kendo (143 +/- 12 msec) and karate (146 +/- 11 msec) athletes were significantly shorter than that in the control (176 +/- 12 msec). The shortenings of the RT were attributed to both the shortenings of premotor time and motor time. The delay of the flexor muscles discharge after those of the extensors in kendo (0.8 +/- 7.0 msec) and karate (-0.2 +/- 5.0 msec) athletes was significantly shorter than in control (12.7 +/-5.6 msec). These results suggest that the RT is shortened through motor learning in the kendo and karate athletes who trained for momentary movements; and that the flexor muscles may play an important role as a synergist in heightening the efficiency of ballistic finger extension in coordination with the extensor muscles.

Adolescent↗

PubMed1999

Serum ubiquitin levels in patients with alcoholic liver disease.

Serum concentrations of free ubiquitin and multiubiquitin chain as determined by immunoassays were compared between 10 healthy subjects, and 11 patients with alcoholic hepatic fibrosis, 10 with alcoholic cirrhosis, and 6 with viral liver cirrhosis. All measurements of multiubiquitin chains were expressed in terms of a standard multiubiquitin chain reference preparation 1. Serum concentrations (mean +/- SD) of free ubiquitin and multiubiquitin chains were significantly higher in patients with alcoholic cirrhosis (63.5 +/- 33.7 ng/ml and 7.5 +/- 4.6 ng/ml) than in the normal subjects (29.6 +/- 6.6 ng/ml, p < 0.05 and 4.1 +/- 1.7 ng/ml, p < 0.05), and those with alcoholic hepatic fibrosis (34.8 +/- 16.3 ng/ml, p < 0.05 and 3.0 +/- 0.7 ng/ml, p < 0.05) and viral liver cirrhosis (28.8 +/- 7.5 ng/ml, p < 0.05 and 4.2 +/- 1.3 ng/ml, p < 0.05). Serum levels of both forms of ubiquitin in six patients with alcoholic cirrhosis showed a tendency to decline after 3 months of abstinence. In a total of 14 patients with alcoholic liver damage, 11 with brain atrophy had significantly higher serum levels of both ubiquitin forms than did three patients without brain atrophy (p < 0.05). No correlation was seen between serum concentrations of either form of ubiquitin and liver function test results in the patients with alcoholic liver damage. However, serum levels of both forms of ubiquitin levels correlated significantly with cumulative alcohol intake (p < 0.05). A significant correlation (p < 0.05) also was observed between serum levels of multiubiquitin chains and mean corpuscular volume, a marker of alcohol consumption. These results suggest that the serum concentrations of ubiquitin, especially multiubiquitin chain is a good marker for the diagnosis of alcoholic cirrhosis.

Adult↗

PubMed1999

Bacterial cell wall polymers promote intestinal fibrosis by direct stimulation of myofibroblasts.

Normal luminal bacteria and bacterial cell wall polymers are implicated in the pathogenesis of chronic intestinal inflammation. To determine the direct involvement of bacteria and their products on intestinal fibrogenesis, the effects of purified bacterial cell wall polymers on collagen and cytokine synthesis were evaluated in intestinal myofibroblast cultures established from normal fetal and chronically inflamed cecal tissues. In this study, the intestines of Lewis rats were intramurally injected with peptidoglycan-polysaccharide polymers. Collagen and transforming growth factor (TGF)-beta1 mRNA levels were measured and correlated with mesenchymal cell accumulation by immunohistochemistry. The direct effects of cell wall polymers on fibrogenic cytokine and collagen alpha1 (type I) expression were evaluated in intestinal myofibroblast cultures. We found that intramural injections of bacterial cell wall polymers induced chronic granulomatous enterocolitis with markedly increased collagen synthesis and concomitant increased TGF-beta1 and interleukin (IL)-6 expression. Intestinal myofibroblast cultures were established, which both phenotypically and functionally resemble the mesenchymal cells that are involved in fibrosis in vivo. Bacterial cell wall polymers directly stimulated collagen alpha1 (I), TGF-beta1, IL-1beta, and IL-6 mRNA expression in the intestinal myofibroblasts derived from both normal and inflamed cecum. Neutralization of endogenous TGF-beta1 inhibited in vitro collagen gene expression. From our results, we conclude that increased exposure to luminal bacterial products can directly activate intestinal mesenchymal cells, which accumulate in areas of chronic intestinal inflammation, thus stimulating intestinal fibrosis in genetically susceptible hosts.

Animals↗

PubMed1999

Differential expression of human lysyl hydroxylase genes, lysine hydroxylation, and cross-linking of type I collagen during osteoblastic differentiation in vitro.

The pattern of lysyl hydroxylation in the nontriple helical domains of collagen is critical in determining the cross-linking pathways that are tissue specific. We hypothesized that the tissue specificity of type I collagen cross-linking is, in part, due to the differential expression of lysyl hydroxylase genes (Procollagen-lysine,2-oxyglutarate,5-dioxygenase 1, 2, and 3 [PLOD1, PLOD2, and PLOD3]). In this study, we have examined the expression patterns of these three genes during the course of in vitro differentiation of human osteoprogenitor cells (bone marrow stromal cells [BMSCs]) and normal skin fibroblasts (NSFs). In addition, using the medium and cell layer/matrix fractions in these cultures, lysine hydroxylation of type I collagen alpha chains and collagen cross-linking chemistries have been characterized. High levels of PLOD1 and PLOD3 genes were expressed in both BMSCs and NSFs, and the expression levels did not change in the course of differentiation. In contrast to the PLOD1 and PLOD3 genes, both cell types showed low PLOD2 gene expression in undifferentiated and early differentiated conditions. However, fully differentiated BMSCs, but not NSFs, exhibited a significantly elevated level (6-fold increase) of PLOD2 mRNA. This increase coincided with the onset of matrix mineralization and with the increase in lysyl hydroxylation in the nontriple helical domains of alpha chains of type I collagen molecule. Furthermore, the collagen cross-links that are derived from the nontriple helical hydroxylysine-aldehyde were found only in fully differentiated BMSC cultures. The data suggests that PLOD2 expression is associated with lysine hydroxylation in the nontriple helical domains of collagen and, thus, could be partially responsible for the tissue-specific collagen cross-linking pattern.

Adolescent↗

PubMed1999

Vascular and stromal changes in irradiated and recovering rat thymus.

To analyze the mechanisms responsible for thymocyte proliferation, maturation and migration in the thymus, the rat thymus just after, and recovering from irradiation was studied morphologically. The vascular structures of the rat thymus after a radiation dose of 6 Gy were found to be destroyed on day 3, but had recovered to almost normal by day 7, suggesting that the abrupt recovery of thymus structure after irradiation was due primarily to this change in vascular structure. Furthermore, the epithelial tissues in the thymic cortex appeared to contribute to this abrupt proliferation, and possibly to the abrupt maturation of thymocytes, while medullary epithelial tissues remained sparse and appeared inactive for a relatively long period. These findings are considered important for understanding the interrelationship between thymic epithelial cells and thymocytes with respect to thymocyte proliferation, maturation and migration.

Animals↗

PubMed1999

A case of ectopic thyroid in lateral neck associated with Graves' disease.

Thyroid follicles in the lateral position of the neck are usually thought to represent the metastasis of thyroid carcinoma. Here we present a case of a 28-year-old woman with accessory ectopic thyroid associated with Graves' disease. Despite a history of Graves' disease poorly controlled with large dose propylthiouracil she was found to be pregnant and artificial abortion was planned. Thyroid scintigraphy was carried out, which indicated an uptake into the region above the left lobe as well as into both lobes of the thyroid gland. In order to control hyperthyroidism and to exclude the possibility of metastasis, total thyroidectomy with tumor resection was performed before the artificial abortion. Pathological examinations of the thyroid gland indicated findings compatible with Graves' disease. The lateral neck mass was revealed to be composed of nonneoplastic thyroid tissue, showing similar histological findings to those of the goiter, which were consistent with Graves' disease. Taken together with several previous reports, it appears that there are some cases with lateral ectopic thyroid tissue, whose pathogenetic mechanism remains to be elucidated.

Abortion, Induced↗

PubMed1999

Identification and immunolocalization of chondroitin sulfate proteoglycans in tooth cementum.

Proteoglycans (PGs) display a great diversity in their core proteins as well as carbohydrate structures and are thought to be involved in many biological functions. Recently we have identified and immunolocalized two keratan sulfate PGs, fibromodulin and lumican, in bovine tooth cementum (Cheng et al., Connect. Tissue Res. 34: 87-96, 1996). The objectives of this study were to identify and characterize chondroitin sulfate (CS) PGs in cementum. In order to explore their potential association with mineral, bovine cementum matrix molecules were fractionated into mineral-unbound and -bound matrices by sequential extraction. Both fractions were subjected to DEAE anion exchange column chromatography and the eluate collected was assayed for C4S and C6S isomers by dot blot immunoassay with specific monoclonal antibodies, 2-B-6 and 3-B-3, respectively. Two families of CSPGs were identified mainly in the mineral-unbound fraction. One contained only C4S glycosaminoglycan and the other both C6S and C4S. By biochemical and immunochemical analyses, decorin and biglycan were identified in the former and versican in the latter. The ratio of C6S to C4S isomers of cementum versican was approximately 7:1. Furthermore, these PGs were immunolocalized in and around tooth cementum using antibodies generated against the respective core proteins. Intensive immunostaining for versican was found almost exclusively in the lacunae housing cementocytes in cementum and osteocytes in alveolar bone, respectively. Immunostaining for decorin was mainly associated with collagen fibers in the periodontal ligament and slightly in cementum matrix, while the one for biglycan was mainly in cementoblasts/precementum. These differential tissue distributions of the CSPGs suggest that they may play distinct roles in cementogenesis.

Animals↗

PubMed1999

Abdominal aortic aneurysm rupture in systemic lupus erythematosus.

Many cardiovascular complications have been described in systemic lupus erythematosus (SLE), however, aortic involvement is very rare. We are reporting abdominal aortic aneurysm rupture in a 47-year old woman with SLE. The patient was admitted to our hospital with severe abdominal pain. Emergency computed tomography of the abdomen demonstrated ruptured abdominal aortic aneurysm. The restoration of aortic flow with vascular prosthesis was performed in emergency. Postoperative course was uneventful.

Aneurysm, Ruptured↗

PubMed1999

[Dynamic mutation and its molecular cytogenetics].

Dynamic mutation, the mechanism of allelic expansion of the heritable unstable triplet repeat DNA sequences, has been the subject of intense investigation since its discovery in 1991 as the molecular basis for fragile X syndrome. The fundamental distinction between dynamic and other forms of mutation is that dynamic mutation is a process rather than a single event. The process involves a relationship between the copy number of perfect repeat DNA sequence and its instability which accounts for the anticipation seen in families carrying a dynamic mutation disease. Recently, dynamic mutation due to allelic expansion of minisatellite repeats has also been demonstrated as either the fragile sites and a genetic disease. In this minireview, dynamic mutations associated with chromosomal fragile sites and their cytogenetics are overviewed.

Chromosome Fragile Sites↗

PubMed1999

[Molecular cytogenetics of fragile X syndrome].

Fragile X syndrome is the most common heritable form of mental retardation, and affects 1 in 1500(male)-2500(female), with minor dysmorphic manifestations such as long face with large protruding ears and macro-orchidism in mentally retarded male patients. The syndrome is caused by dynamic mutation(trinucleotide repeat expansion) at FRAXA located on the long arm of X chromosome. Molecular diagnosis enables carrier identification as well as prenatal diagnosis, in which the cytogenetic method was not feasible. Premutation in phenotypically normal carriers and full mutation in mentally retarded patients explain the characteristic inheritance of the disease called anticipation. This article describes the recent advancements in molecular cytogenetics of fragile X syndrome.

Anticipation, Genetic↗

PubMed1999

[Cardiovascular responses during laryngeal mask airway insertion in normotensive, hypertensive and chronic renal failure patients].

The hemodynamic response to the insertion of the laryngeal mask airway (LM) following induction with propofol 2 mg.kg-1 was assessed and compared in normotensive (Normal), hypertensive (HT) and chronic renal failure (CRF) patients (n = 23 in each group). Before induction, in HT and CRF groups blood pressure and rate pressure products (RPP) were higher than in Normal group (P < 0.05). Although blood pressure and RPP were decreased in every patient by induction with propofol, no patients needed vasopressor drugs. The decreases of blood pressure and RPP were larger in HT and CRF groups than in Normal group (P < 0.05). There were no differences between groups in heart rate and rate of successful LM insertion. We concluded that LM insertion with propofol 2 mg.kg-1 was an effective induction method preventing the adverse circulatory responses in normotensive, hypertensive and chronic renal failure patients.

Adult↗

PubMed1999

[Predictive evaluation and efficient management of medical examinations using Mahalanobis Taguchi System Method].

UNLABELLED: The Mahalanobis-Taguchi System (MTS), an evaluative technique used in quality engineering, was utilized in a system analysis of medical examinations to determine practicability, to differentiate cost reduction benefits of specific components for increasing efficiency, and to determine possibility of utility on forecasting of future health condition of individuals. METHODS: 1. Medical examination date over a two year period were utilized to differentiate subject into two groups: Group A--Healthy or normal; and Group C--Patient group requiring treatment or currently undergoing treatment. The Mahalanobis distance for Group C from the Mahalanobis space of Group A was calculated for each subject to determine differentiability. 2. Utilizing the MTS method specific components of the examination system were selected and analyzed for effectiveness in diagnosis and screening to enhance efficiency of the examination. 3. Group A subjects (determined from the two year data), were analyzed using the data at the end of 1 year to develop the Mahalanobis space and the Mahalanobis distance at the 2nd year point was calculated and analyzed. RESULTS: 1. Subjects who were classified as group A at both 1st and 2nd year points numbered 159. With a cutoff point of 2.0 for Mahalanobis distance 98.1% of the healthy subjects (Group A) were classified as belonging to the healthy group, and 91.9% of C group as belonging to the patient group. 2. Blood pressure, GOT, GPT, gamma-GTP, T Chol, TG, UA, Cr, BS, HbA1c, Hb, and MCH were found to be effective components in the examination. Based on this result the items included in the examination can be reduced by approximately 60%. 3. With cutoff value of 1.5, the results of 90% of subjects 1 year later could be predicted. The prediction that 15% of Group C subjects would improve to join Group A could be made. Overall, the results 1 year later could be predicted at a level of 90% accuracy. CONCLUSION: These results suggest that the Mahalanobis-Taguchi System technique can accurately assess medical examination quality and can also be used, with reasonable accuracy, to predict the condition of individuals one year later. Therefore, the MTS can be used to help determine which patients should be receiving the examination 1 year later. In addition, components of the examination can be assessed using the MTS for benefits and costs to determine levels of essentiality of components. As a result, it can be used an effective tool for development and improvements in the examination system. With further development in the technique, it may become possible for use as a tool in disease diagnosis and treatment.

Cost-Benefit Analysis↗

PubMed1998

Evidence for mRNA expression of vascular endothelial growth factor by X-ray irradiation in a lung squamous carcinoma cell line.

Vascular endothelial growth factor (VEGF) is a multipotent cytokine which plays an important role in various angiogenic conditions as well as in some tumor behaviors. Here we examined the induction of VEGF mRNA by X-ray irradiation in a lung squamous cell carcinoma cell line (RERF-LC-AI). Irradiating the cells with 15 Gy X-rays significantly increased the mRNA expression up to 2.5-fold of control at a post-irradiation time of 16-24 h. The induction of VEGF mRNA by X-ray irradiation was completely blocked by treating cells with either genistein (Src tyrosine kinase inhibitor) or H7 (protein kinase C inhibitor). This suggests that the mechanism of induction might be concerned with the pathway which triggers Src tyrosine kinase of the cell surface and the protein kinase C pathway.

Antineoplastic Agents↗

PubMed1998

Collagen abnormalities in the spinal cord from patients with amyotrophic lateral sclerosis.

During the last 10 years, we have demonstrated morphological and biochemical abnormalities of skin extracellular matrices in amyotrophic lateral sclerosis (ALS). However, currently little is known concerning collagen of the spinal cord in ALS. We measured the amount of collagen and characterized collagen at light and electron microscopic levels in posterior funiculus, posterior half of lateral funiculus and anterior horn of cervical enlargement of the spinal cord obtained from ten patients with ALS, 11 patients with other neurologic diseases (control group A), and ten patients without neurologic ones (control group B). In posterior half of lateral funiculus and anterior horn, (1) by light microscopy, there was no significant difference in vessel wall area between ALS patients and control groups A and B; (2) ultrastructurally, collagen bundles were more fragmented and widely separated, and the fibrils were randomly oriented in the perivascular space of capillaries in ALS patients, which were not observed in any areas of control groups or in posterior funiculus of ALS patients; and (3) the collagen contents in ALS were significantly lower (P<0.001 and P<0.001, respectively) than those in control groups A and B. Fragmented and widely separated collagen bundles in the interstitial tissue surrounding capillaries and markedly decreased amount of collagen in posterior half of lateral funiculus and in anterior horn of ALS could be related to the degeneration of the upper and lower motor neurons in the spinal cord in ALS, that is, selective neuronal vulnerability in ALS.

Adult↗

PubMed1998

An ATP-ADP switch in MuB controls progression of the Mu transposition pathway.

MuB protein, an ATP-dependent DNA-binding protein, collaborates with Mu transposase to promote efficient transposition. MuB binds target DNA, delivers this target DNA segment to transposase and activates transposase's catalytic functions. Using ATP-bound, ADP-bound and ATPase-defective MuB proteins we investigated how nucleotide binding and hydrolysis control the activities of MuB protein, important for transposition. We found that both MuB-ADP and MuB-ATP stimulate transposase, whereas only MuB-ATP binds with high affinity to DNA. Four different ATPase-defective MuB mutants fail to activate the normal transposition pathway, further indicating that ATP plays critical regulatory roles during transposition. These mutant proteins fall into two classes: class I mutants are defective in target DNA binding, whereas class II mutants bind target DNA, deliver it to transposase, but fail to promote recombination with this DNA. Based on these studies, we propose that the switch from the ATP- to ADP-bound form allows MuB to release the target DNA while maintaining its stimulatory interaction with transposase. Thus, ATP-hydrolysis by MuB appears to function as a molecular switch controlling how target DNA is delivered to the core transposition machinery.

Adenosine Diphosphate↗