Search PubMed⌕ Search

Biomedical subjects

H Yamaguchi

Publications and source records attributed to H Yamaguchi.

At least 415 records · Page 23Linked to original sources

Alteration of intracellular Na+ during ischemia in diabetic rat hearts: the role of reduced activity in Na+/H+ exchange against stunning.

To elucidate the contribution of reduced activity of Na+/H+ exchange in streptozotocin-induced diabetic hearts against stunning, intracellular Na+ concentration ([Na+]i) was measured in isolated rat hearts using 23Na-MRS. The recovery of left ventricular developed pressure in hearts reperfused after 15 min global ischaemia at 37 degreesC was significantly better in diabetic ones (102.9+/-2.0% of pre-ischemic level, mean+/-s.e., n=6; P<0.05), and non-diabetic ones pre-treated with potent Na+/H+ exchange inhibitor, EIPA (1 mu mol/l; 93.8+/-2.3%, n=5; *P<0.05) than non-treated, non-diabetic hearts (75.1+/-2.5%, n=8). When diabetic hearts were pre-treated with EIPA, the recovery (101.2+/-2.6%, n=5) was identical to that of non-treated, diabetic hearts. [Na+]i in non-diabetic hearts increased to 329.1+/-8.1% of pre-ischemic level during 15 min ischemia, whereas the increase in [Na+]i in diabetic hearts significantly suppressed to 199.8+/-10.3% (P<0.001). EIPA attenuated the increase of [Na+]i during ischemia to 189.1+/-9.0% in non-diabetic hearts ( P<0.001) and to 155.3+/-4.6% in diabetic hearts (P<0.05). Thus, the EIPA-dependent Na+ accumulation during ischemia, i.e. Na+ influx probably mostly via Na+/H+ exchange was smaller in diabetic hearts by 69.7% compared with that in non-diabetic hearts. These results indicate that the cardiac protection against stunning in streptozotocin-induced diabetic hearts is mediated by the attenuation of Na+ accumulation during ischemia, which is caused by the reduced activity in Na+/H+ exchanger.

Adenosine Triphosphate↗

Difference in the mechanisms for compensating ischemic acidosis in diabetic rat hearts.

To elucidate the difference in the mechanisms for alkalization during ischemic acidosis between diabetic and non-diabetic hearts, intracellular pH (pHi) was measured by phosphorus-31 magnetic resonance spectroscopy. Diabetes was induced by the injection of streptozotocin. The accumulation of proton ion (DeltaH+) during 15 min global ischemia at 37 degreesC was calculated from pH i. There were no significant differences in DeltaH+ between diabetic (DM: 0. 54+/-0.03 micromol/l,n=6; mean+/-s.e.m.) and non-DM hearts (0.57+/-0.04, n=6), when perfused with bicarbonate buffer. However, perfusion with HEPES buffer revealed a significant increase of DeltaH+ in DM (0.85+/-0.07, n=5) compared with non-DM (0.61+/-0.06, n=5P<0.05). On the contrary, the addition of a Na+/H+ exchange inhibitor (EIPA; 1 micromol/l) to bicarbonate buffer significantly increased DeltaH+ in non-DM (1.09+/-0.10, n=4) compared with DM (0.71+/-0.03, n=5P<0.01). Perfusion with HEPES buffer and EIPA equally increased DeltaH+ in both groups (DM 1.13+/-0.13, n=4; non-DM 1.15+/-0.14, n=4). Thus, the activity of Na+/H+ exchanger during ischemic acidosis, assessed as the increase of DeltaH+ induced by addition of EIPA to bicarbonate buffer, was higher in non-DM (0.52) than DM (0.17). In contrast, the contribution of bicarbonate-dependent systems evaluated by the deference of DeltaH+ between the bicarbonate buffer and the HEPES buffer was markedly bigger in DM (0.31) than non-DM (0.04). These results indicate that Na+/H+ exchange is a major mechanism to compensate ischemic acidosis in non-DM hearts, whereas bicarbonate-dependent systems compensate the depressed activity of Na+/H+ exchange in DM.

Acidosis↗

High-Resolution Infrared Diode Laser Spectroscopy of Ne-N2O, Kr-N2O, and Xe-N2O.

The rotationally resolved spectra of the van der Waals complexes Ne-N2O, Kr-N2O, and Xe-N2O have been investigated in the region of the nu3 N2O monomer vibrational band using a diode laser absorption spectrometer that is incorporated with a multipass cell and a pulsed jet. The spectra of these three complexes are completely analyzed using a normal asymmetric rotor Hamiltonian, and the effective molecular constants are accurately determined for both the ground and the excited vibrational states. These results show that, like Ar-N2O, the complexes have a T-shaped configuration in which the rare gas atom prefers to lie near to the oxygen side of N2O. The band origins of Rg-N2O (Rg = Ne, Ar, Kr, and Xe) are observed to shift by 0.36125, 0.15038, -0.10131, and -0.49066 cm-1 from that of the monomer, respectively. These band origin shifts are well explained by a simple model for the intermolecular potential. Copyright 1998 Academic Press.

Journal Article↗

Ventricular pressure-volume area (PVA) accounts for cardiac energy consumption of work production and absorption.

We briefly review that ventricular systolic pressure-volume area (PVA) can predict changes in myocardial O2 consumption (VO2) associated with cardiac work production (positive work) and absorption (negative work). PVA represents the total mechanical energy of cardiac contraction as it is an integral of mechanical energy generated during systole in the cardiac chamber. We have shown that PVA linearly correlates with VO2 under varied pre- and afterload conditions in the left ventricle of the excised cross-circulated canine heart preparation as well as other heart preparations of different species. PVA is the sum of external mechanical work (EW) and mechanical potential energy (PE) which is almost fully convertible to mechanical work without affecting VO2. To compare the energetic effects of cardiac work production and absorption, we varied the timing of the servo pump motion relative to left ventricular (LV) contraction. When the pump fills the LV during diastole and sucks (allows ejection) during systole, cardiac work is produced by the heart, and hence EW > 0. When the pump fills the LV during systole and sucks during diastole, work is absorbed by the heart, and hence EW < 0. The pressure-volume loop rotates counterclockwise when EW > 0. It rotates clockwise when EW < 0. As the result, PVA (= PE + EW) > PE when EW > 0; PVA < PE when EW < 0. We found that VO2 always linearly correlated with PVA regardless of the polarity of EW. Therefore, PVA is the unique determinant of VO2 in a cardiac chamber in a stable contractility.

Animals↗

Enhanced anti-Candida activity of neutrophils and azole antifungal agents in the presence of lactoferrin-related compounds.

We investigated the effects of lactoferrin (Lf)-related compounds on growth inhibition of Candida albicans by neutrophils or antifungal agents in vitro. Human neutrophils partially inhibited the growth of C.albicans. The growth inhibition caused by human neutrophils was augmented by the addition of human Lf at concentrations which did not show any inhibitory effect in the absence of neutrophils. Similar observations were obtained also with the following combinations: human neutrophils + bovine Lf, murine neutrophils + bovine Lf, and murine neutrophils + iron saturated bovine Lf, but not in the case of murine neutrophils + human transferrin. The minimum inhibitory concentration (MIC) of azole antifungal agents, clotrimazole, ketoconazole, fluconazole, and itraconazole was reduced by 1/4 to 1/16 in the presence of a sub-MIC level of each of bovine Lf, bovine Lf pepsin hydrolysate, and the antimicrobial peptide "lactoferricin B" (Lfcin B). Other types of antifungal agents, amphotericin B, nystatin, and flucytosine did not show such combined effects with these Lf-related compounds. The anti-Candida activity of bovine Lf or Lfcin B in combination with clotrimazole was shown to be synergistic by checkerboard analysis. Clinically isolated azole-resistant C. albicans strains were more susceptible to bovine Lf or Lfcin B than azole-susceptible strains. Trailing growth of an azole-resistant strain in the presence of fluconazole was reduced by the addition of sub-MIC levels of bovine Lf or Lfcin B. These results suggest that Lf-related compounds even at relatively low concentrations may function as an antifungal effector in combination with neutrophils thereby modulating azole antifungal efficacies in vivo.

Animals↗

Glucose tolerance and myocardial F-18 fluorodeoxyglucose uptake in normal regions in coronary heart disease patients.

To elucidate the relation between glucose tolerance and myocardial uptake of F-18 fluorodeoxyglucose (FDG), FDG-PET with 75 g oral glucose loading was performed on 43 coronary artery disease patients (twice in 2 patients). The patients were divided into 4 groups based on the blood glucose level (BS) and the insulinogenic index (II): group 1, normal (n = 9); group 2, impaired glucose tolerance (IGT, n = 12); group 3, mild diabetes mellitus (DM) (II > 0.4, n = 12); and group 4, severe DM (II < or = 0.4, n = 12). Percent (%) dose uptake of FDG in the normal regions of the myocardium was not significantly different in groups 1, 2, and 3, but it was much lower in group 4 than in groups 1 and 2. In groups 2, 3, and 4, % dose uptake showed a definite negative correlation with BS 60 min after glucose loading (r = -0.450, p < 0.05), and a close positive correlation with II (r = 0.363, p < 0.05). These findings indicate that myocardial FDG uptake in normal regions is not greatly impaired in patients with IGT or mild DM. Myocardial viability can be assessed by oral glucose loading in patients with IGT and mild DM as well as in patients with normal glucose tolerance.

Aged↗

Results of the Bosworth method for unstable fractures of the distal clavicle.

Eleven consecutive Neer's type II unstable fractures of the distal third of the clavicle were treated by open reduction and internal fixation, using a temporary Bosworth-type screw. In all cases, fracture healing occurred within 10 weeks. Shoulder function was restored to the pre-injury level. A Bosworth-type screw fixation is a relatively easy and safe technique of open reduction and internal fixation of type II fractures of the distal third of the clavicle.

Accidental Falls↗

Diffuse plaques associated with astroglial amyloid beta protein, possibly showing a disappearing stage of senile plaques.

To clarify whether senile plaques disappear, we examined amyloid beta protein (A beta) deposits in non-demented subjects, and found novel diffuse plaques associated with astroglial A beta. Formalin-fixed paraffin-embedded sections from cortical areas were immunolabeled with a panel of A beta antibodies, and astroglial and microglial markers. Cerebral A beta deposition was primarily found as diffuse plaques (DP) in these subjects. A subset of DP was associated with clusters of intensely A beta-positive small granules. The clusters, which were located just adjacent to astroglial nucleus, had the characteristics of lipofuscin granules and, therefore, were quite different from "small stellate deposits". Substantial amounts of A beta-positive granules were found inside astrocytes by dual labeling of A beta and glial fibrillary acid protein, and the majority of astroglial A beta immunoreactivity was located on lipofuscin granules. A beta-positive granules lacked immunoreactivity with antisera for the N-terminal region of A beta. These peculiar DP showed a much weaker staining than ordinary DP. The DP associated with astroglial A beta were found in about one third of the subjects, although the density varied widely among individuals. From these findings, we propose that DP, which are associated with the N-terminal truncated A beta in astrocytes, represent the disappearing stage of senile plaques.

Aged↗

Identification of a novel splicing mutation and 1-bp deletion in the 17alpha-hydroxylase gene of Japanese patients with 17alpha-hydroxylase deficiency.

We report studies of two unrelated Japanese patients with 17alpha-hydroxylase deficiency caused by mutations of the 17alpha-hydroxylase (CYP17) gene. We amplified all eight exons of the CYP17 gene, including the exon-intron boundaries, by the polymerase chain reaction and determined their nucleotide sequences. Patient 1 had novel, compound heterozygous mutations of the CYP17 gene. One mutant allele had a guanine to thymine transversion at position +5 in the splice donor site of intron 2. This splice-site mutation caused exon 2 skipping, as shown by in vitro minigene expression analysis of an allelic construct, resulting in a frameshift and introducing a premature stop codon (TAG) 60 bp downstream from the exon 1-3 boundary. The other allele had a missense mutation of His (CAC) to Leu (CTC) at codon 373 in exon 6. These two mutations abolished the 17alpha-hydroxylase and 17,20-lyase activities. Restriction fragment length polymorphism (RFLP) analysis with a mismatch oligonucleotide showed that the patient's mother and brother carried the splice-site mutation, but not the missense mutation. Patient 2 was homozygous for a novel 1-bp deletion (cytosine) at codon 131 in exon 2. This 1-bp deletion produces a frameshift in translation and introduces a premature stop codon (TAG) proximal to the highly conserved heme iron-binding cysteine at codon 442 in microsomal cytochrome P450 steroid 17alpha-hydroxylase (P450c17). RFLP analysis showed that the mother was heterozygous for the mutation.

Adolescent↗

Physiologic stress responses to laparoscopic cholecystectomy. A comparison of the gasless and pneumoperitoneal procedures.

BACKGROUND: Differences in the physiological stress response to pneumoperitoneal (PP) and gasless abdominal wall-lifting (AWL) procedures used for laparoscopic cholecystectomy have not been properly evaluated. METHODS: We compared leukocyte count, interleukin-6 (IL-6) levels, arterial blood gases, creatinine clearance, plasma renin activity, cardiothoracic ratio, and clinical outcome in 27 patients without systemic complications who underwent laparoscopic cholecystectomy, including 11 by AWL and 16 by PP. RESULTS: Transient leukocytosis and high IL-6 levels were observed at POD 1 (postoperative day) in both groups, but both values returned to baseline by POD 2. IL-6 levels correlated significantly with operation time (p < 0.01). Changes in blood gases, creatinine clearance, plasma renin activity, and cardiothoracic ratio were not different for the two groups. The clinical outcome was similar for both groups. CONCLUSIONS: Our results indicate that both PP and AWL are appropriate for patients without serious complications.

Adult↗

Chromosome instability evaluated by fluorescence in situ hybridization in hereditary non-polyposis colorectal cancer.

Numerical aberrations of chromosome 17 and nuclear DNA content were compared in patients with hereditary non-polyposis colorectal cancer (HNPCC) and those with sporadic colorectal cancer (SCRC). During a period of 22 years, 30 cases (3.2%) from 28 families satisfied the Japanese clinical criteria of HNPCC. Using freshly frozen tissue samples, we investigated chromosomal aberration with fluorescence in situ hybridization with alpha satellite DNA probe for chromosome 17. Flow cytometric quantification of nuclear DNA content showed DNA aneuploidy in 9 of 15 patients (60.0%) with HNPCC and in 160 of 234 patients (68.4%) with SCRC, there was no significant difference between HNPCC and SCRC. The mean proportion of nuclei with aneusomy 17 (numerical chromosome aberration index: NCAI) in 14 patients with HNPCC was significantly higher than that in 42 patients with SCRC (46.8 +/- 5.0% vs 39.0 +/- 10.3%, P < 0.01). NCAI increased in proportion with the progression of the disease in SCRC (26.1% in stage I, 33.3% in stage II, 38.8% in stage IIIa, 42.7% in stage IIIb, and 46.2% in stage IV, P < 0.01), whereas NCAI in HNPCC was high in all stages (43.5%-49.2%). The proportion of patients with multiple numerical aberration of chromosome 17 was significantly higher in HNPCC (9/14) than among SCRC (11/42). Our data suggest that chromosome 17 is present in an unstable condition in HNPCC.

Adenocarcinoma↗

Importance of cytogenetic markers for multiple primary carcinomas in colorectal cancer: chromosome 17 and p53 locus translocation.

The incidence of non-familial multiple primary cancer in colorectal cancer patients has increased in recent years in Japan. To clarify the characteristic genetic aberrations in such multiple cancers, we examined structural chromosomal aberrations by fluorescence in situ hybridization, using chromosome 17-specific and p53 cosmid DNA probes. We established short-term cultures of 78 surgical specimens and were able to obtain observable metaphase spreads in 23 single colorectal cancer specimens and in 6 colorectal cancer specimens from patients with double primary cancers. The frequency of chromosome 17 and/or p53 locus translocation was significantly greater in tumors with double cancer than in single colorectal cancers (P < 0.05 and P < 0.01, respectively). These aberrations in double cancers frequently appeared even at an early Dukes' stage (A and B) of colorectal carcinoma. Our results suggest that translocation of chromosome 17 and the p53 locus may be specific genetic events probably associated with carcinogenesis of multiple primary cancers in colorectal cancer.

Biomarkers, Tumor↗

Endothelial sodding of the Permaflow prosthetic coronary artery bypass conduit.

BACKGROUND: Experiments were designed to determine the feasibility of sodding an endothelial monolayer within the lumen of a prosthetic conduit applied to the canine coronary circulation. METHODS: Autologous endothelial cells were sodded onto the luminal surface of the Permaflow conduit and immediately implanted to bypass the left circumflex coronary artery in adult mongrel dogs (n = 9). Unsodded Permaflow conduits were implanted as controls (n = 8). At 3 weeks, grafts were explanted and examined by scanning electron microscopy and immunostained for canine von Willebrand factor. RESULTS: Sodded grafts contained a confluent endothelial cell layer devoid of adherent thrombus or platelets and stained positively for canine von Willebrand factor. Unsodded grafts contained no endothelium and retained adherent platelets, collagen, and fibrin. Effluent from sodded grafts stimulated with calcium ionophore A23187 caused a significantly greater relaxation of its bioassay ring than effluent from unsodded grafts (60%+/-21% versus 12%+/-5%; n = 8, p < 0.03). CONCLUSIONS: Sodding of endothelial cells onto a Permaflow coronary artery bypass graft results in a confluent, viable, nonthrombogenic, endothelial monolayer and releases vasodilator substances in response to calcium ionophore A23187. Endothelial sodding may optimize prosthetic grafts.

Animals↗

Activation of tau protein kinase I/glycogen synthase kinase-3beta by amyloid beta peptide (25-35) enhances phosphorylation of tau in hippocampal neurons.

According to the amyloid hypothesis for the pathogenesis of Alzheimer's disease (AD), amyloid beta peptide (Abeta) directly affects neurons, leading to neurodegeneration and tau phosphorylation, followed by the production of paired helical filaments (PHF) in neurofibrillary tangles (NFT). To analyze the relationship between the phosphorylation sites of tau and the activation of kinases in response to Abeta, we treated cultured rat hippocampal neurons with a peptide fragment of Abeta, Abeta(25-35). Abeta(25-35) treatment activated tau protein kinase I/glycogen synthase kinase-3beta (TPKI/GSK-3beta) but not glycogen synthase kinase-3alpha (GSK-3alpha) or mitogen activated protein kinase (MAP kinase) in primary culture of hippocampal neurons. Using antibodies that recognize phosphorylated sites of tau, we showed that tau phosphorylation was enhanced in at least five sites (Ser199, Ser202, Ser396, Ser404, and Ser413 numbered according to the human tau isoform containing 441 amino acid residues), to an extent that depended on the level of TPK I/GSK-3beta. Treatment with TPK I/GSK-3beta antisense oligonucleotide inhibited the enhancement of tau phosphorylation induced by Abeta(25-35) exposure. Thus, TPK I/GSK-3beta activation by Abeta(25-35) may lead to extensive tau phosphorylation.

Amyloid beta-Peptides↗

Altered cholinergic mechanisms and blood pressure regulation in the rostral ventrolateral medulla of DOCA-salt hypertensive rats.

We examined whether cholinergic transmission in the rostral ventrolateral medulla (RVLM) of deoxycorticosterone acetate-salt hypertensive rats (DHR) is enhanced and the enhancement is involved in the maintenance of hypertension in DHR, and whether cholineacetyltransferase (ChAT) activities and ChAT mRNA expression are enhanced in neurons intrinsic to the RVLM of DHR. Rats were anesthetized, paralyzed, and artificially ventilated. Unilateral microinjection of cholinergic agents into the RVLM produced a pressor response. The pressor response to physostigmine was greater in DHR than in control rats, whereas the response to carbachol was the same in both sets of rats. Bilateral microinjection of scopolamine into the RVLM produced a decrease in blood pressure. The depressor response was greater in DHR than in control rats. The number of ChAT-activity-detected neurons in the RVLM was greater in DHR than in control rats. The number of ChAT mRNA-expressing neurons in the RVLM was also clearly greater in DHR than in control rats. These results demonstrate that cholinergic transmission in the RVLM is enhanced in DHR, and this enhancement may play a role in the maintenance of hypertension in DHR. It is probable that enhanced activity of cholinergic neurons intrinsic to the RVLM is at least in part, responsible for the enhanced cholinergic transmission in the RVLM of DHR.

Animals↗

High transepidermal water loss induces fatty acid synthesis and cutaneous fatty acid-binding protein expression in rat skin.

Stratum corneum lipids (SCLs) are responsible for the water barrier function (WBF) of the skin in mammals. Recent studies have indicated that epidermal lipid synthesis might be regulated by WBF of stratum corneum and that cutaneous fatty acid-binding protein (C-FABP) plays an important role in fatty acid metabolism in epidermis. To clarify the regulatory mechanism of lipid synthesis, we assessed the effects of barrier disruption induced by either acetone treatment or linoleic acid deficiency on epidermal lipid synthesis in rat. Transepidermal water loss (TEWL) was measured with an evaporimeter before and after treatment. The time course of re-establishing SCLs was examined biochemically and histochemically and the expression of C-FABP in the epidermis was immunohistochemically examined. When the rat skin was covered with a vapor-impermeable membrane after the acetone treatment removing SCLs and inducing WBF disruption, the usual recovery of SCLs was blocked and TEWL was kept high by 24 h. In the uncovered area, rapid redeposition of SCLs within 24 h was found and associated with normal compositions of epidermal lipids including sphingolipids, free fatty acids and sterol and, immunohistochemically, C-FABP was very weakly expressed in epidermis at 0.5 and 2 h, and then strongly in the whole layers at 4 h, and returned to a normal pattern by 8 h. The epidermis of the covered rat skin was kept weak in C-FABP expression by 24 h. In the linoleic acid-deficient rats, TEWL did not increase and the expression pattern of C-FABP showed no notable change until 28 weeks after initiation of the diets, indicating that C-FABP expression may not be affected by altered essential fatty acid metabolism. These results suggest that increase of TEWL itself stimulates C-FABP expression, leading to activation of fatty acid metabolism.

Acetone↗

Effect of probucol on smooth muscle cell proliferation and dedifferentiation after vascular injury in rabbits: possible role of PDGF.

We previously reported a clinical study in which probucol reduced the restenosis rate. The mechanism of this effect is unclear. Restenosis is characterized by neointimal hyperplasia caused by proliferation of smooth muscle cells (SMCs), which increases the expression of Platelet-derived growth factor (PDGF)-A and SMemb. SMemb, a non-muscle-type myosin heavy chain most predominantly expressed in embryonic smooth muscle, can be used as a good molecular marker for dedifferentiated SMC. The aim of this study was to analyze the effect of probucol on neointimal proliferation and the level of expression of PDGF-A and SMemb after balloon injury in rabbits. Probucol was given orally 1.3 g/d from 2 weeks prior to carotid balloon injury to the time of killing (2 or 4 weeks after balloon injury). Intimal area was determined histologically using a computerized morphometry program. For quantification of SMC proliferation, alpha-actin-positive cells and proliferating cell nuclear antigen (PCNA)-labeled cells were counted. The expression of PDGF-A and SMemb mRNA was analyzed by the RNase protection assay. SMemb expression was also examined by immunohistochemistry. Probucol remarkably decreased intimal area by 70% and the number of SMC and PCNA-labeled cells in the intima. The expression of PDGF-A mRNA was significantly increased after balloon injury in untreated rabbits, whereas it was markedly suppressed with probucol treatment. The expression of SMemb was significantly increased in injured arteries at mRNA and protein levels. However, probucol did not suppress SMemb expression. Probucol is effective in preventing SMC proliferation, which is possibly due to a decrease in the expression of PDGF.

Angioplasty, Balloon↗

Significance of angiogenic factors in liver metastatic tumors originating from colorectal cancers.

We examined the expression of vascular endothelial growth factor (VEGF) and microvessel counts expressed by CD34 staining in 39 patients with primary and 44 patients with metastatic liver tumors of metastatic colorectal carcinoma, and 29 patients with nonmetastatic colorectal carcinoma as control in order to determine their value in the evaluation of prognosis and recurrence after hepatectomy. Microvessel counts in primary colorectal carcinomas of the metastatic group were significantly higher than those in control (P<0.05). Neither factor correlated with any clinicopathological feature of primary or metastatic liver carcinomas. Higher microvessel counts in metastatic liver tumors tended to be associated with a shorter disease-free interval to second recurrence in the remaining liver (P = 0.069) and were significantly associated with poor prognosis after hepatectomy (P<0.05). We conclude that microvessel count is an important marker of liver metastasis and prognosis in patients with colorectal carcinoma treated with hepatectomy.

Adult↗