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Biomedical subjects

M Yamauchi

Publications and source records attributed to M Yamauchi.

At least 145 records · Page 8Linked to original sources
PubMed1997

Onset of vecuronium neuromuscular blockade at the hand with an arterio-venous shunt.

PURPOSE: To evaluate the onset of vecuronium neuromuscular blockade in the hand with an arterio-venous shunt for haemodialysis. METHODS: In 15 adult patients receiving haemodialysis for renal failure the onset of vecuronium-induced neuromuscular blockade after 0.08 mg-kg-1 vecuronium i.v. was measured. Using train-of-four mechanomyographic monitoring, the force of contraction of the adductor pollicis of both hands with and without arterio-venous shunt was measured simultaneously. RESULTS: The times from the injection to the first depression of twitch response (latent onset) and 95% twitch depression (onset) in the hand with and without arterio-venous shunt were 114.7 +/- 33.4 and 218.7 +/- 59.9 and 117.3 +/- 34.3 and 208.7 +/- 60.9 sec respectively. No difference in the onset of vecuronium neuromuscular blockade in the hand an arterio-venous shunt was demonstrated. CONCLUSION: The presence of an arteriovenous fistula does not modify the onset on neuromuscular blockade. Either arm can be used to monitor onset of neuromuscular blockade in chronic renal failure patients with an arterio-venous shunt in the hand for haemodialysis.

Adult↗
PubMed1997

The effects of transmural pressure on prostacyclin release from porcine endocardial endothelial cells--comparison with vascular endothelial cells.

We assessed the effect of pressure on the release of prostacyclin (PGI2) from cultured endocardial endothelial cells (EECs) and vascular endothelial cells (VECs). EECs were harvested from the right ventricle (RV) and left ventricle (LV) of porcine hearts, and VECs from pulmonary artery (PA), aorta (Ao) and coronary artery (CA). Confluent EECs and VECs were incubated for 30 min under various pressures (0, 50, 100, 150 mmHg) and PGI2 release from each cell was measured. Pressure-induced PGI2 release from LV-EECs was larger than that from RV-EECs. Pressure also increased PGI2 release from both PA- and Ao-VECs, but not from CA-VECs. These findings suggest that endocardium can produce PGI2 in response to pressure and PGI2 released into the coronary blood from the ventricle may play an important role in the prevention of myocardial ischemia.

Animals↗
PubMed1997

Analysis of sweat evaporation from clothing materials by the ventilated sweat capsule method.

The local influence of three clothing materials i.e. silk, cotton and nylon, in (1) full or (2) partial skin contact or (3) at 3 mm from the skin, on sweat evaporation from the chest skin surface of human subjects was studied. The hygrometer-ventilated capsule method was used and sweating was induced at ambient thermoneutrality by a central heat load following lower-leg immersion in water at 43 degrees C. The presence of clothing delayed the rise in capsule relative humidity (CRH) induced by heat loading. During the first 6 min of heating, CRH rose more steeply with clothing that was in full skin contact than with clothing that had partial or no contact. The rate of decrease in CRH from 1 min to 6 min after heating was not influenced by the presence of clothing or by the different degrees of skin contact. The subsequent return of CRH to the pre-heating level was delayed most by cotton, less by silk and least by nylon. For silk and nylon, partial contact with the skin prolonged the return to control conditions, as compared with full skin contact.

Adult↗
PubMed1997

Sweating economy by graded control in well-trained athletes.

Local sweat rates (Msw) at the chest and thigh and the frequency of sweat expulsions (Fsw) were determined in human subjects with (athletes) or without (non-athletes) long-term physical training during moderate bicycle exercise (80 W for 30 min) at ambient thermoneutrality (23 degrees C) and 60% relative humidity. There was a tendency for Msw to be lower in athletes. The rise of Msw with increasing Fsw was significantly less steep and Fsw was also controlled at a significantly lower rate in athletes than in non-athletes. The start of exercise was followed by a temporary decrease in mean skin temperature (Ts) which was less distinct in athletes. The rise in Ts at the end of exercise was significant in athletes (0.80 +/- 0.26 degree C) but not in non-athletes (0.26 +/- 0.33 degree C). The results indicate that long-term physical training leads to improved circulatory heat transfer to the skin and to a more graded nervous control of sweat expulsion and, further, tends to reduce the rate of sweating.

Adult↗
PubMed1997

Antithrombotic effects of endocardial endothelial cells-comparison with coronary artery endothelial cells.

The purpose of this study was to assess the anti-platelet properties of endocardial endothelial cells (EECs) by measuring platelet aggregation after a brief incubation with cultured EECs. EECs were isolated from the right ventricles of porcine hearts and coronary artery endothelial cells (C-ECs) were also isolated from the same animals. After brief incubations (2-min) of platelet suspensions with cultured EEC and CEC monolayers, platelet aggregation in response to thrombin and 6-keto-PGF1 alpha (a stable metabolite of PGI2) content of platelet suspensions were measured. Platelet aggregation was significantly inhibited by a brief incubation of platelet suspensions with EEC and C-ECs monolayers. Pretreatment of EECs and C-ECs with indomethacin (5 x 10(-5) M) restored platelet activity, but pretreatment with N omega-nitro-L-arginine methyl ester (L-NAME, 5 x 10(-5) M) or hemoglobin (1 x 10(-6) M) did not. Platelet/EEC interactions multiplicatively increased the 6-keto-PGF1 alpha content of platelet suspensions and the 6-keto-PGF1 alpha content of platelet suspensions after incubations with EECs correlated significantly with the inhibition of platelet aggregation. Both the anti-aggregation properties and 6-keto-PGF1 alpha production were significantly greater in EECs than in C-ECs. A brief incubation (2-min) with PDGF (10 ng/ml) or TGF-beta (1 and 10 ng/ml) stimulated 6-keto-PGF1 alpha production in EECs but not in C-ECs, although these growth factors stimulated 6-keto-PGF1 alpha production in C-ECs after a longer incubation time (30 or 60 min). In this study, after a brief incubation (2-min) with platelet suspensions, EECs inhibited platelet aggregation mainly through the release of PGI2 but not EDRF. As this anti-aggregation property was significantly greater in EECs than in C-ECs, it is suggested that endocardial endothelial PGI2 may inhibit both intracardiac and intracoronary artery thrombus formation, contributing to the prevention of myocardial ischemia.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Hydroxyl radical scavenging effect of nicaraven in myocardial and coronary endothelial preservation and reperfusion injury.

OBJECTIVE: We investigated the efficacy of nicaraven in reducing myocardial as well as coronary endothelial preservation-reperfusion (P/R) injury. METHODS: In experiment I, isolated rat hearts were mounted on a Langendorff (L) apparatus to estimate the baseline cardiac function. Group 1, 8- and 12-h storage in histidine-tryptophan-ketoglutarate (HTK) solution; group 2, 8- and 12-h storage in HTK solution with superoxide dismutase (2.5 x 10(5) U/I) and catalase (2 x 10(5) U/I); group 3, 8- and 12-h storage in HTK solution with nicaraven (10(-3) M). Following storage for 8 and 12 h at 4 degrees C, they were reperfused and post-preservative cardiac function was evaluated. The hearts were then switched back to L-mode and paced at 330 beats/min. Coronary flow (CF) following perfusion with KHB solution containing 5-hydroxytryptamine (5-HT) and nitroglycerin was also measured. In experiment 2, segments of pig coronary artery were suspended in organ chambers and exposed to hydroxyl radicals in the presence or absence of nicaraven. The sensitivity of relaxation response to bradykinin of the prior-exposed rings was measured. RESULTS: The recovery of CF and LV dp/dt following 8 h of storage in group 3 was higher than that in group 1, although there were no significant differences in the other parameters of cardiac functional recovery among the groups. The absolute values of cardiac function following 12 h of storage in groups 1-3 were as follows: 6.6 +/- 2.4, 9.1 +/- 0.8, 15.6 +/- 3.1 ml/min of cardiac output (CO); 1.9 +/- 0.9, 2.3 +/- 0.4, 6.0 +/- 2.3 ml/min of aortic flow (AF); 4.5 +/- 1.3, 6.0 +/- 0.5, 9.5 +/- 0.8 ml/min of CF, respectively. The recovery of CO, AF, CF, SP, MP, and left ventricular (LV) dp/dt were significantly improved in group 3, compared with those in group 1. CF and CO in group 3 were higher than those in group 2.5-HT caused vasoconstriction in all groups, but the vasoconstriction in group 3 was less than in group 1. Prior exposure to FeSO4/H2O2 produced significant endothelial damage as reflected by the right-ward shift of the dose-response curve of bradykinin-induced endothelium-dependent relaxation. In the presence on nicaraven, the dose-response curve recovered to the control level. CONCLUSIONS: Nicaraven may improve coronary endothelial and myocardial function following P/R by its hydroxyl radical scavenging activity.

Animals↗
PubMed1997

Obstructive ileus caused by a swallowed foreign body (a "press-through" package) and preexisting adhesions.

A "press-through" package (PTP), because it is large and square-shaped, tends to be caught in the esophagus when swallowed. A rare case of obstructive ileus induced by a PTP that was swallowed by 54-year-old man with a history of diabetes mellitus and acute appendectomy is reported. The PTP was 19 mm x 18 mm and was lodged in the cecum, which was stenosed because of preexisting intestinal adhesions; consequently, the PTP obstructed the ileus. The PTP was surgically removed.

Constriction, Pathologic↗
PubMed1997

Alteration of mineral crystallinity and collagen cross-linking of bones in osteopetrotic toothless (tl/tl) rats and their improvement after treatment with colony stimulating factor-1.

A common feature of various types of mammalian osteopetroses is a marked increase in bone mass accompanied by spontaneous bone fractures. The toothless (tl/tl) rat osteopetrotic mutation is characterized by drastically reduced bone resorption due to a profound deficiency of osteoclasts and their precursors. An altered bone morphology has also been observed. The mutants cannot be cured by bone marrow transplantation, but skeletal defects are greatly reduced after treatment with colony stimulating factor 1 (CSF-1). The objectives of this study were to characterize mineral and collagen matrices in cancellous and compact bone isolated from long bones of 6-week-old normal littermates, tl/tl osteopetrotic mutants and mutants (tl/tl) treated with CSF-1. There were no differences in bone mineral content, but a significant decrease in the crystallinity of mineral evaluated by the method based on electron paramagnetic resonance spectrometry was observed in all bones of tl/tl mutants as compared to that of controls. Within the collagen matrix, slight decreases in the labile cross-links, but significant increases in the content of the stable cross-links, pyridinoline, and deoxypyridinoline, were observed in both cancellous and compact bone of osteopetrotic mutants. In tl/tl mutants treated with human recombinant CSF-1, the normalization of the crystallinity of bone mineral as well as collagen cross-links was found. Our results indicate that remodeling of bone matrix in tl/tl mutants is highly suppressed, but that after treatment with CSF-1, this activity recovers significantly. Taken together, these data provide further support for the hypothesis that CSF-1 is an essential factor for normal osteoclast differentiation and bone remodelling.

Animals↗
PubMed1997

Mineral induction by immobilized phosphoproteins.

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

Acid Phosphatase↗
PubMed1997

A case of sarcoid reaction associated with papillary thyroid carcinoma.

Sarcoid reaction, a granulomatous lesion similar to those seen in sarcoidosis, has been reported to be associated with various disorders. Here we describe a 54-year-old woman, who was diagnosed with sarcoid reaction associated with papillary carcinoma of the thyroid. Her history included total thyroidectomy with radical neck dissection for a papillary carcinoma of the thyroid. She was found to have a right subclavian mass. Dissection of the mass was performed for the diagnosis of metastatic papillary carcinoma to the lymph node, but the pathological examination showed granuloma without caseation as well as metastasis to the lymph node. Polymerase chain reaction (PCR) of the specimen excluded a possibility of Mycobacterium infection. There was no supporting evidence for systemic sarcoidosis in this patient; the patient showed no skin, eye, or lung lesions, or bilateral hilar lymphadenopathy, and she did not show increase in serum gamma-globulin or in plasma angiotensin-converting enzyme (ACE) levels, or increased CD4/CD8 ratio of lymphocytes obtained from bronchoalveolar lavage. These findings suggest that the present case had sarcoid reaction associated with papillary carcinoma. Although sarcoid reaction has been reported to be associated with various malignancies, only five cases, to our knowledge, are reported in the literature, which were associated with papillary carcinoma.

Carcinoma, Papillary↗
PubMed1997

Double product response is accelerated above the blood lactate threshold.

Catecholamine concentrations are known to increase sharply in the blood at work rates above the blood lactate threshold (LT); thus, we hypothesized that the double product (DP, heart rate-systolic blood pressure product) may also abruptly increase at work rates above the LT. Ninety healthy students performed a stepwise incremental test on a cycle ergometer. The slopes of the two regression lines below and above the LT for the heart rate (HR), the indirectly measured systolic blood pressure (SBP), and the DP, respectively, were compared using VO2 as an independent variable. For all three parameters the slope of the regression line above the LT was significantly higher than that below the LT. Although either the same or a lower slope was found in the HR (N = 23) or SBP (N = 22) responses in some subjects above the LT as compared with that below the LT, a steeper DP slope above the LT was evident in all 90 subjects. The same results were also obtained during 4-min constant work rate exercise sessions at a variety of submaximal intensities performed in a random order in seven subjects. In addition, we established the DP break point (DPBP) determining protocol with a fairly good test-retest reliability (r = 0.951) and a correlation coefficient between the DPBP and the LT (r = 0.900). These results suggest that the DP increases more steeply above the LT, and, as a result, the DPBP is considered to be a valid and useful parameter as a marker of the LT.

Adult↗
PubMed1997

Effects of recombinant interleukin-1 beta on decorin gene expression in human periodontal ligament fibroblast and its possible transcriptional regulation.

Interleukin-1 beta (IL-1 beta) is a potent regulator of osteoprogenitor cells and fibroblasts, and is believed to be responsible for the bone loss and connective tissue breakdown that occurs in periodontitis. Decorin, a major small proteoglycan in the periodontium, has been shown as an important mediator of the organization of the pericellular and extracellular matrix. Since the HPLF play a significant role in the regulation of extracellular matrix metabolism, it was important to clarify the causal relationship between cytokines, HPLF and proteoglycans. We investigated the effect of IL-1 beta on decorin gene expression and its functional regulation to elucidate the intracellular mechanism mediating the action of IL-1 beta. Quiescently confluent HPLF cultures were incubated for different treatment periods with various concentrations of IL-1 beta and/or 10(-4) M cycloheximide (Cx) in culture medium supplemented with 1% charcoal-stripped serum for different treatment periods. Northern hybridization analyses, using decorin cDNA probe, showed that IL-1 beta increased the abundance of decorin mRNA in both a dose- and time-dependent manner. Most of the stimulation was blocked by Cx, indicating that the regulation of decorin gene expression by IL-1 beta may be via an indirect pathway, requiring new protein synthesis which regulates the promoter. Gel mobility shift analyses detected the specific DNA binding activity of a nuclear extract of AP-1, but not NF-kappa B, that could bind to the recognition site of decorin gene promoter fragments with the increased abundance in IL-1 beta treatment groups. These results suggest that the increased transcription of decorin gene by HPLF in the presence of IL-1 beta is mediated at least in part through the interaction of AP-1 with the decorin gene promoter.

Alveolar Bone Loss↗
PubMed1997

Identification, partial characterization, and distribution of versican and link protein in bovine dental pulp.

The dynamics of changes in the cellularity and extracellular matrix composition of dental pulp varies considerably during tooth development and maturation. In this paper, we studied matrix proteoglycans where we hypothesized that they played important roles in structural, spatial, and transport aspects of pulpal development and maintenance. The pulpal tissue was collected from partially erupted bovine incisors, pulverized, and then extracted with 6 M guanidine-HCl. The extract was subjected to anion column chromatography (DEAE-8HR), and the fractions collected were screened by dot-blot immunoassay by means of monoclonal antibodies generated against 4- and 6-sulfated chondroitin sulfate isomers, and keratan sulfate, 2-B-6, 3-B-3, and 5-D-4, respectively. The chondroitin-6-sulfate was the major glycosaminoglycan species and occurred as a large-molecular-weight proteoglycan (> 500 kDa). After further purification, it was subjected to agarose/acrylamide composite gel electrophoresis, and it migrated as a single band stained with Stains-All. The band was immunopositive against antibody 3-B-3 by Western blot analysis. The partial amino acid sequence analyses of the core protein clearly indicated this molecule to be versican. The presence of link protein was also confirmed by Western blot analysis with an anti-link protein monoclonal antibody, 8-A-4. Furthermore, immunohistochemical study indicated that the distributions of versican and link protein coincide in the dental pulp and are enriched in the peripheral area of the tissue just beneath the odontoblast layer. Since the dental pulp contains hyaluronan, versican may bind to hyaluronan via its hyaluronan-binding domain, where this association is stabilized by link protein. This complex, then, could form large hydrated proteoglycan aggregates that fill the extracellular space, support odontoblasts, and/or facilitate the transport function of metabolites and nutrients within the tissue.

Amino Acid Sequence↗
PubMed1997

Morphological and flow cytofluorometrical analyses of regenerated rat thymus after irradiation.

Reconstituted rat thymuses were studied by immunohistochemistry, transmission electron microscopy (TEM) and flow cytofluorometry on days 0, 1, 2, 3, 5, and 7 after whole-body sublethal irradiation (6 Gy). One day after irradiation, numerous apoptotic cells were seen in the cortical thymus; the percentage of the sub-G1 peak representing apoptotic cells was 8.9% in the DNA content histogram of cytofluorometry. On day 3, the thymic structure had been destroyed and no distinction was drawn between the cortex and medulla. In this stage, few thymocytes but many macrophages were present, and the percentage of the sub-G1 peak reached a peak at 13.0%. Bromodeoxyuridine (BrdU) incorporated cells gradually increased after irradiation, and immunohistochemically numerous apoptotic cells were found primarily in the cortex on day 7. These thymocytes showed some levels of electron density of the nucleus as revealed by TEM. The percentage of S phase cells did not change markedly (20-30%) based on one-color DNA content histograms, but the percentage of early S and S phase cells was extremely high on day 7 (70%). These data indicate that a part of DNA synthetic cells may result in apoptosis. The combination of immunohistochemistry, TEM and flow cytofluorometry to analyze DNA content and BrdU incorporation proved a useful tool for investigating the reconstituted thymus.

Animals↗
PubMed1997

[A curative report of multiple organ dysfunction syndrome and disseminated intravascular coagulation due to methicillin-resistant Staphylococcus aureus caused mediastinitis after cardiac surgery].

We experienced a curative case, who was a fifty nine-year old man suffered from multiple organ dysfunction syndrome (MODS) and disseminated intravascular coagulation (DIC) due to Methicillin-resistant Staphylococcus aureus (MRSA) caused-mediastinitis following cardiac surgery against atrial septal defect (ASD) and tricuspid regurgitation. We successfully treated him with mediastinal irrigations by a large quantities of physiological saline containing 1% Povidone iodine (PI) and MRSA sensitive antibiotics as well as artificial supports such as plasma pheresis and hemodialysis against failure organs. It may be due to the prompt treatment with mediastinal irrigation and well timed dosage of sensitive antibiotics against the origin of sepsis that such a serious patient like this case could be recovered from MODS and DIC. In addition, it may be very effective to irrigate with 1% PI against MRSA-caused-mediastinitis.

Cardiac Surgical Procedures↗
PubMed1997

[Re-rupture of intracranial aneurysm caused by insertion of an intraventricular drainage tube].

A 42-year-old man was admitted to our hospital with subarachnoid hemorrhage, requiring the clipping of an intracranial aneurysm and removal of intracranial hematoma. Anesthesia was induced with thiamylal and maintained with oxygen-nitrous oxide-isoflurane. Trimethaphan was administered continuously and his systolic blood pressure was stably maintained between 100-110 mmHg. Seven minutes after insertion of an intraventricular drainage tube through the dura, his blood pressure increased to 146/76 mmHg. By transdural echogram, re-rupture of the aneurysm was confirmed, and after 6 minutes, a fresh intracranial hematoma was observed. The decrease of intracranial pressure following insertion of the intraventricular drainage tube or the stimulation by several intraventricular punctures seems to have caused re-rupture of the aneurysm. When hemodynamic change is observed without obvious cause in a patient with subarachnoid hemorrhage, it is important to speculate that a re-rupture of the aneurysm has occurred, and to treat the problem accordingly.

Adult↗
PubMed1997

[Tricuspid valve replacement for infectious endocarditis associated with ventricular septal defect--report of three cases].

We reported two male and one female patient (17, 36 and 47 years old, respectively) who presented infectious endocarditis (IE) in association with ventricular septal defect (VSD). In all cases, surgical treatment was performed in the acute stage of IE for persistent sepsis, pulmonary embolisms, and for giant vegetations. Because the tricuspid valve apparatus was severely damaged, valve replacement with the Carpentier-Edwards pericardial bioprosthesis was done and small VSD was directly closed in all cases. In one case, a complete heart block occurred, which necessitated postoperative implantation of a permanent pacemaker. All patients recovered and resumed their original social activities without the relapse of endocarditis.

Adolescent↗