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Biomedical subjects

T Yamaguchi

Publications and source records attributed to T Yamaguchi.

At least 307 records · Page 17Linked to original sources
PubMed2000

Expression of parathyroid hormone-related protein in human and experimental atherosclerotic lesions: functional role in arterial intimal thickening.

We investigated the expression of parathyroid hormone-related protein (PTHrP) in atherosclerotic lesions and the role of PTHrP in the development of arterial neointima formation. Immunohistochemical staining of PTHrP in the neointima of rat aorta produced by balloon injury and of rat femoral artery produced by non-obstructive polyethylene cuff placement, and in the atherosclerotic lesion of human coronary artery was performed using anti-human PTHrP-(1-34) antibody. Anti-muscle actin antibody, HHF-35, and anti-macrophage antibody, HAM-56, were used to identify smooth muscle cells and macrophages, respectively. Immunoreactivity of PTHrP was detected in the thickened intima of rat and human lesions where the predominant cell types were smooth muscle cells or macrophages dependently on the lesion type. In the next series of experiments, we examined the effect of PTHrP on the development of cuff-induced intimal thickening of rat femoral artery. Either PTHrP-(1-34) or PTHrP-(7-34), a PTH/PTHrP receptor antagonist, suspended in pluronic F-127 gel was locally applied around the rat femoral artery. Intimal thickening induced by cuff placement was evaluated 2 weeks later. PTHrP-(1-34) dose-dependently inhibited intimal thickening determined as intima/media ratio and % stenosis whereas PTHrP-(7-34) dose-dependently enhanced that. These results suggest that PTHrP, which is expressed in atherosclerotic lesions, inhibits the development of neointimal formation.

Analysis of Variance↗
PubMed2000

Theoretical study of intracellular stress fiber orientation under cyclic deformation.

We studied stress fiber orientation under a wide range of uniaxial cyclic deformations. We devised and validated a hypothesis consisting of two parts, as follows: (1) a stress fiber aligns to avoid a mechanical stimulus in the fiber direction under cyclic deformation. This means that, among all allowable directions, a stress fiber aligns in the direction which minimizes the stimulus, i. e., the summation of the changes in length of the stress fiber over one stretch cycle; and (2) there is a limit in the sensitivity of the cellular response to the mechanical stimulus. Due to this sensing limit, the orientation angle in stress fibers is distributed around the angle corresponding to the minimum stimulus. To validate this hypothesis, we approximated an anisotropic deformation of the membrane on which cells were to be cultured. We then obtained the relationships between the stretch range and the fiber angle in the undeformed state which minimize the mechanical stimuli, assuming that the membrane on which stress fibers and cells adhered was homogeneous and incompressible. Numerical simulation results showed that the proposed hypothesis described our previous experimental results well and was consistent with the experimental results in the literature. The simulation results, taking account of the second part of the hypothesis with a small value for the limit in sensitivity to the mechanical stimulus, could explain why cell orientation is distributed so widely with cyclic stretch ranges of <10%. The proposed hypothesis can be applied to various types of deformation because the mechanical stimulus is always sensed and accumulates under cyclic deformation without the necessity of a reference state to measure the stimulus.

Animals↗
PubMed2000

Computational mechanical model studies on the spontaneous emergent morphogenesis of the cultured endothelial cells.

To address questions concerning why and how the morphology of endothelial cells (ECs) forms under shear stress loading, a computational fluid dynamics (CFD) three-dimensional (3D) model of ECs simulating cell shape was designed. A full 3D non-linear CFD simulation was conducted to estimate the wall shear stress (WSS) distribution. The model cell was capable of random rotation, deformation, migration, and proliferation. Flow was computed after each update of the cell shape with infinitesimal configuration changes. After a finite interval of the flow computation, only the infinitesimal configuration changes that reduced the WSS were allowed to accumulate. As a result of the very long free-run computation experiment, starting with a sub-confluent pattern of cells, the model cells became confluent and were elongated and aligned, with a shape index (SI) very close to that reported for cells in vivo. The average WSS converged to the lowest value at the same time.

Algorithms↗
PubMed2000

Acute promyelocytic leukemia with del(6)(p23).

We report a unique case of de novo acute promyelocytic leukemia (APL) with cryptic 15;17 rearrangements. Cytogenetically, structural rearrangements of the 6p23 region has been reported mainly in secondary leukemia. This patient had a karyotype of 46, XY, del(6)(p23) and no additional chromosomal abnormalities. Molecular analyses revealed the presence of PML-RAR alpha fusion genes. Deletion of the 6p23 region is extremely rare in APL.

Aged↗
PubMed2000

Characterization of tynorphin, a potent endogenous inhibitor of dipeptidyl peptidaseIII.

To find a more effective inhibitor than spinorphin (LVVYPWT), an endogenous factor derived from bovine spinal cord, we synthesized spinorphin analogues and assayed their inhibitory activity toward DPPIII among enkephalin-degrading enzymes. Tynorphin (VVYPW), an N-terminal and C-terminal truncated form of spinorphin, exhibited more potent inhibitory activity and an IC50 value of 0.086 +/- 0.05 microg/ml (n = 4), whereas structures smaller than four amino acid residues exhibited almost no or less activity, suggesting that a five amino acid structure containing a Tyr-Pro residue is essential for the inhibition. The inhibition of DPPIII by tynorphin was predominantly competitive and the Ki value was found to be 7. 50 +/- 1.19 x 10(-8) M on Lineweaver-Burk plotting. The inhibitory activity of tynorphin toward other enkephalin-degrading enzymes such as neutral endopeptidase, aminopeptidase, and angiotensin-converting enzyme was not as high as that toward DPPIII, suggesting that tynorphin is a specific inhibitor of DPPIII. In HPLC analysis, human serum cleaved tynorphin rapidly (38% of control at 2 h and background level at 4 h), but in the presence of leuhisitin, an aminopeptidase inhibitor, tynorphin was maintained at the original level for 24 h. These results indicated that tynorphin had a more effective structure for expression of inhibitory activity toward DPPIII.

Animals↗
PubMed2000

Effect of probucol in a murine model of slowly progressive polycystic kidney disease.

Epithelial proliferation, extracellular matrix remodeling, and interstitial inflammation are central elements in the pathogenesis of slowly progressive polycystic kidney disorders. Probucol, an antioxidant that lowers plasma cholesterol, has been shown to decrease smooth muscle cell proliferation and macrophage accumulation in blood vessels and to prevent restenosis after coronary angioplasty. We determined in 30-day-old male BDF1-pcy hybrid mice (derived from mating DBA/2FG-pcy and C57BL/6FG-pcy) the effect of probucol administered in the diet (1%) for 200 days on kidney weight relative to body weight (KW/BW), cyst expansion, renal interstitial fibrosis, and serum urea nitrogen (SUN) concentration. Animals were fed a moderately high-protein diet (HPD, 36%) to accentuate the development of renal cysts and to promote interstitial fibrosis. Probucol decreased serum cholesterol from 68 to 16 mg/dL but had no effect on food intake or body weight. Probucol decreased relative kidney size from 4.16% +/- 0.55% to 2.64% +/- 0.12% KW/BW (P < 0.01), SUN from 30.5 +/- 1.8 to 25.9 +/- 1.0 mg/dL (P < 0.05), cystic index from 2.45 +/- 0.11 to 1.36 +/- 0.10 (P < 0.01), and fibrosis index from 2.40 +/- 0.11 to 1.82 +/- 0.08 (P < 0.01). We conclude that probucol ameliorates the progressive deterioration in renal function and structure in pcy mice ingesting a relatively high level of dietary protein.

Animals↗
PubMed2000

Dominant expansion of human T cells in non-obese diabetic/severe combined immunodeficiency mice implanted with human bone fragments.

OBJECTIVE: To establish an in vivo animal model in which human T cells develop and function normally, a step toward developing new vaccines or chemical compounds that modulate immune functions and toward understanding T-cell immunity in humans. MATERIALS AND METHODS: Human bone fragments were implanted into non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice. The presence of human blood cells in the peripheral blood of these mice was monitored periodically by immunostaining and fluorescence-activated cell sorting. RESULTS: After implantation of bone fragments, dominant expansion of human T lymphocytes, rather than myeloid and B cells, was observed over a 3-month period. In some cases, the proportion of human T cells rose to 40% of the peripheral blood mononuclear cells. These T cells showed CD4/CD8 ratios similar to those observed in human peripheral blood lymphocytes and had a broad repertoire of rearranged T-cell receptor genes. Graft-versus-host reaction was not noted in any organ analyzed. To assess the suitability of NOD/SCID mice implanted with human bone fragments (hu-bone-NOD/SCID mice) as an in vivo model for HIV infection, the mice were infected with a T-lymphotropic strain of HIV-1 (NL4-3) at 7 weeks posttransplant. Serum p24 gag was detected at 2 weeks after inoculation, after which total CD4-positive cell numbers declined, as seen clinically in patients infected with HIV. CONCLUSION: Although the precise mechanism is yet to be determined by which predominant expansion of human T cells occurs in hu-bone-NOD/SCID mice, such mice appear likely to serve as a useful and versatile model for studies involving human T-cell immunity.

Animals↗
PubMed2000

Evaluation of posterior cerebral artery flow velocity by transcranial color-coded real-time sonography.

Using transcranial color-coded real-time sonography (TCCS), we measured peak-systolic flow velocities (PSVs) in segment P2 of 102 posterior cerebral arteries (PCAs) in 61 patients, with angiography. We divided 102 PCAs into four groups: control group (n = 70) with no significant stenotic lesions; PCS group (n = 7) with stenosis >/= 50% of P2 segment; Col (+) group (n = 13) and Col (-) group (n = 12) had occlusive lesions in the carotid system with or without collateral flow from PCA to the middle cerebral artery through the leptomeningeal anastomosis. In the PCS group, PSV (255.7 +/- 67.2 cm/s) was higher than in the other three groups (p < 0.0001). PSV was higher in the Col (+) group (127.6 +/- 31.2) than in the Col (-) (86.6 +/- 20.1) and control (83.8 +/- 24.8) groups (p < 0.001). The measurement of PSV in the P2 segment of PCA using TCCS may help to identify a significant stenosis in PCA.

Blood Flow Velocity↗
PubMed2000

Maxillary sinus development and sinusitis in patients with cleft lip and palate.

OBJECTIVE: Sinusitis is frequently associated with cleft lip and palate. The present study was performed in an attempt to investigate maxillary sinus development in relation to the occurrence of sinusitis in cleft patients. METHODS: Forty-seven consecutive patients with cleft lip and alveolus with or without cleft palate underwent computed tomographic scans of the maxilla. The cross-sectional area of the maxillary sinus at the level of the zygomatic arch was measured, and the soft tissue density shadow of the sinus was scored on a 4-point scale. RESULTS: The cross-sectional area of the sinus was significantly smaller in the child group (10 years or less) than in the adolescent group (11-20 years, P<0.001) and the adult group (over 20 years, P<0.02). The cross-sectional area significantly increased with age in the child group (r=0.552, P<0.001). The growth rate became slower in the adolescent group. The cross-sectional area then gradually decreased with age in the adult group (r=-0.64, P<0.05). Sinusitis was observed in 15 patients (32%) and in 20 sinuses (21%). Severe sinusitis was more common in the child group than in the patients over 10 years of age (P<0.05). CONCLUSION: These results indicate that maxillary sinusitis associated with cleft lip and palate occurs preferably in the developing sinuses of children.

Adolescent↗
PubMed2000

Coronary flow velocity immediately after primary coronary stenting as a predictor of ventricular wall motion recovery in acute myocardial infarction.

OBJECTIVES: The purpose of this study was to examine the relationship between the pattern of coronary blood flow velocity immediately after successful primary stenting and the recovery of left ventricular (LV) wall motion in patients with acute myocardial infarction (AMI). BACKGROUND: It is difficult to predict the recovery of LV wall motion immediately after direct angioplasty in AMI. Recent reports indicate that dysfunctional coronary microcirculation is an important determinant of prognosis for AMI patients after successful reperfusion. METHODS: We measured left anterior descending coronary flow velocity variables using a Doppler guide wire immediately after successful primary stenting in 31 patients with their first anterior AMI. The patients were divided into two groups: those with and those without early systolic reverse flow (ESRF). Changes in LV regional wall motion (RWM) and ejection fraction (EF) at admission and at discharge were compared between the two groups. Coronary flow velocity variables immediately after primary stenting were compared with changes in left ventriculographic indexes. RESULTS: The change in RWM was significantly greater in the non-ESRF group than it was in the ESRF group (0.9 +/- 0.7 vs. -0.1 +/- 0.3 standard deviation/chord, respectively, p < 0.001). The change in EF was also significantly greater in the non-ESRF group than it was in the ESRF group (10 +/- 10 vs. 1 +/- 6%, respectively, p < 0.05). In the non-ESRF group (diastolic to systolic velocity ratio [DSVR] <3.0), the DSVR correlated positively with the change in RWM (r = 0.60, p < 0.005, n = 24) and the change in EF (r = 0.52, p < 0.01). CONCLUSIONS: The coronary flow velocity pattern measured immediately after successful primary stenting is predictive of the recovery of regional and global LV function in patients with AMI.

Aged↗
PubMed2000

Treatment of osteopenia secondary to primary hyperparathyroidism.

A major challenge in the management of primary hyperparathyroidism (pHPT) is the decision regarding which patients should undergo parathyroidectomy (PTX). although the Consensus Development Conference of the National Institutes of Health (NIH) has proposed guidelines for the indication of surgery. We found that PTX brings about increases in radial and lumbar BMD values as high as 10% in virtually all pHPT patients including postmenopausal women and those without an indication for surgery based on NIH criteria. Serum alkaline phosphatase (ALP) level and the severity of cortical bone mass reduction are clinically useful for predicting the changes in lumbar BMD after PTX. The present findings provide a useful clue for the indication of surgery in pHPT, and seem to warrant a more extended indication than that of the NIH. We also described the recent progress in studies on calcium-sensing receptor (CaR), and discussed the possibility of bone mass recovery by medical treatment of pHPT with a newly introduced CaR agonist ('calcimimetics').

Absorptiometry, Photon↗
PubMed2000

Detection of plasmalogen from plasma low density lipoprotein and high density lipoprotein in carp, Cyprinus carpio, and rainbow trout, Oncorhynchus mykiss.

The study revealed the presence of plasmalogens in the low density lipoprotein (LDL) and high density lipoprotein (HDL) of the fish. The composition of the plasmalogen in the carp plasma LDL phospholipids was 0.94 and 0.23% in the HDL; the LDL phospholipids in the rainbow trout were 0.44% and the HDL was 0.18%. Aldehydes from the plasmalogen were derivatized with dansylhydrazides and separated by high performance liquid chromatography (HPLC). Their presence was detected using a fluorescence detector. Hexadecanal (C16: 0), octadecanal (C18: 0) and octadecenal (C18: 1) were determined to be the major components in the carp and rainbow trout.

Animals↗
PubMed2000

Bilateral transcapholunate dislocation.

An uncommon case has been reported of bilateral transscaphoid-perilunate dislocation fracture following trauma. A 35-year-old male with bilateral transscapholunate dislocation was treated by closed reduction and internal fixation. The case was examined in detail, and compared to the findings in the literature; observations regarding fracture prognosis were also made. Two years post-surgery, the patient remained asymptomatic.

Accidental Falls↗
PubMed2000

Extracellular calcium-sensing-receptor (CaR)-mediated opening of an outward K(+) channel in murine MC3T3-E1 osteoblastic cells: evidence for expression of a functional CaR.

The existence in osteoblasts of the G-protein-coupled extracellular calcium (Ca(o)(2+))-sensing receptor (CaR) that was originally cloned from parathyroid and kidney remains controversial. In our recent studies, we utilized multiple detection methods to demonstrate the expression of CaR transcripts and protein in several osteoblastic cell lines, including murine MC3T3-E1 cells. Although we and others have shown that high Ca(o)(2+) and other polycationic CaR agonists modulate the function of MC3T3-E1 cells, none of these actions has been unequivocally shown to be mediated by the CaR. Previous investigations using neurons and lens epithelial cells have shown that activation of the CaR stimulates Ca(2+)-activated K(+) channels. Because osteoblastic cells express a similar type of channel, we have examined the effects of specific "calcimimetic" CaR activators on the activity of a Ca(2+)-activated K(+) channel in MC3T3-E1 cells as a way of showing that the CaR is not only expressed in those cells but is functionally active. Patch-clamp analysis in the cell-attached mode showed that raising Ca(o)(2+) from 0.75 to 2.75 mmol/L elicited about a fourfold increase in the open state probability (P(o)) of an outward K(+) channel with a conductance of approximately 92 pS. The selective calcimimetic CaR activator, NPS R-467 (0.5 micromol/L), evoked a similar activation of the channel, while its less active stereoisomer, NPSS-467 (0.5 micromol/L), did not. Thus, the CaR is not only expressed in MC3T3-E1 cells, but is also functionally coupled to the activity of a Ca(2+)-activated K(+) channel. This receptor, therefore, could transduce local or systemic changes in Ca(o)(2+) into changes in the activity of this ion channel and related physiological processes in these and perhaps other osteoblastic cells.

Animals↗
PubMed2000

Administration of bacterial lipopolysaccharide to rats induces heme oxygenase-1 and formation of antioxidant bilirubin in the intestinal mucosa.

Heme oxygenase (HO)-1, the rate-limiting enzyme in heme degradation, is induced by oxidative stress and its major end product, bilirubin, is a potent physiological antioxidant. We studied the induction of HO-1 and bilirubin production in intestinal mucosa using a rat model of sepsis. E. coli lipopolysaccharide was administered intraperitonealy to male Wistar rats and intestinal mucosa was harvested. Intestinal lipid peroxides increased significantly at 1 hr and peaked at 170% of the control value at 5 hr. GSH significantly decreased at 3 hr, reaching the nadir of 50% of the control value at 5 hr. HO-1 mRNA was maximally induced fivefold at 3 hr and HO-1 protein maximally increased to 10 times the control value at 7.5 hr. Both bilirubin and bilirubin oxidative metabolites were maximally increased at 10 hr, to 4.3 and 3.7 times the control value, respectively. These data suggest that oxidative stress in sepsis quickly induces HO-1 in intestinal mucosa and that subsequent production of bilirubin works as an antioxidant. The small intestinal mucosa is an active participant in the general response to sepsis.

Animals↗
PubMed2000

Association of Clara cell 10-kDa protein, spontaneous regression and sarcoidosis.

Sarcoidosis is a systemic granulomatous disorder with a high rate of spontaneous regression. Clara cell 10-kDa protein (CC10), the predominant product of nonciliated bronchiolar epithelial cells, is a potent immunoregulatory and anti-inflammatory agent. CC10 levels were measured in sera and bronchoalveolar lavage (BAL) fluids from 31 sarcoidosis patients (nine progressive disease and 22 regressive disease) and their relevance to spontaneous regression investigated. The inhibitory effects of recombinant CC10 on interferon gamma (IFN-gamma) production were examined using lipopolysaccharide (LPS)-stimulated sarcoid BAL fluid cells, and the blocking effects of monoclonal antibody TY-5, directed against CC10, on CC10 function were also tested. Serum and BAL fluid CC10 levels in the regressive disease group were significantly higher than those in the progressive disease group (serum, p<0.05; BAL fluid, p<0.005) and healthy subjects (serum, p<0.0001; BAL fluid, p<0.005). CC10 inhibited, in part, IFN-gamma production from LPS-stimulated sarcoid BAL fluid cells (CC10 inhibition: 1,000 ng x mL(-1), 30%; 100 ng x mL(-1), 14%). TY-5 restored IFN-gamma production by blocking CC10 function. Sarcoidosis patients with regressive disease showed increased Clara cell 10-kDa protein levels in their sera and bronchoalveolar lavage fluids. Clara cell 10-kDa protein may be a regulator of the inflammatory process in sarcoidosis.

Adult↗