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Biomedical subjects

T Yamaguchi

Publications and source records attributed to T Yamaguchi.

At least 361 records · Page 20Linked to original sources
PubMed2000

Regional differences of metabolism in human masseter muscle by two-dimensional 31P-chemical shift imaging.

Many reports have demonstrated significant region-dependent differences in the fiber-type composition of the human masseter muscle. Therefore, it is considered that there is intramuscular heterogeneity of metabolic activity in the muscle. The present study was carried out, with two-dimensional Chemical Shift Imaging, to detect differences between the deep and superficial parts of the human masseter muscle at rest. Masseter muscle from 11 volunteers, from 20 to 27 years old, was examined, and characteristic spectra of the inorganic phosphate (Pi), phosphocreatine (PCr), and alpha-, beta-, and gamma-adenosine triphosphate (ATP) from each part of the muscles were obtained. In this study, the deep and superficial parts of the masseter muscle were distinguished by the existence of aponeurosis. The Pi/PCr, PCr/beta-ATP, and Pi/beta-ATP ratios as well as the pH in the deep and superficial parts were calculated from the peak spectra. Compared with the deep part, the Pi/PCr of the superficial part was lower (p < 0.05) and the PCr/beta-ATP was higher (p < 0.01). The Pi/beta-ATP and pH showed no significant differences between the two parts. The results indicate that the superficial part of the masseter muscle contains more PCr than the deep part, and this may be related to functional differences between these two parts. In future examinations of the metabolic activity of the human masseter muscle, the deep and superficial parts must be measured separately.

Adenosine Triphosphate↗
PubMed2000

Mechanical circulatory assist for pulmonary embolism.

Optimal management of acute pulmonary embolism remains controversial, despite advances in thrombolytic therapy. Haemodynamic instability and, in particular, right ventricular dysfunction is associated with poor outcomes. Urgent surgical embolectomy has been the treatment of choice in this category of patients. We present two cases in which percutaneous cardiopulmonary support (PCPS) was used as an adjunct to thrombolytic therapy for progressive circulatory collapse secondary to massive acute pulmonary embolism. This experience suggests that PCPS may offer an attractive option for a condition which continues to carry significant morbidity and mortality.

Adult↗
PubMed2000

Extracellular calcium-sensing receptor expression and its potential role in regulating parathyroid hormone-related peptide secretion in human breast cancer cell lines.

Metastasis of breast cancer to bone occurs with advanced disease and produces substantial morbidity. Secretion of PTH-related peptide (PTHrP) from breast cancer cells is thought to play a key role in osteolytic metastases and is increased by transforming growth factor-beta (TGFbeta), which is released from resorbed bone. Elevated extracellular calcium (Ca2+(o)) also stimulates PTHrP secretion from various normal and malignant cells, an action that could potentially be mediated by the Ca2+(o)-sensing receptor (CaR) originally cloned from the parathyroid gland. Indeed, we previously showed that both normal breast ductal epithelial cells and primary breast cancers express the CaR. In this study we investigated whether the MCF-7 and MDA-MB-231 human breast cancer cell lines express the CaR and whether CaR agonists modulate PTHrP secretion. Northern blot analysis and RT-PCR revealed bona fide CaR transcripts, and immunocytochemistry and Western analysis with a specific anti-CaR antiserum demonstrated CaR protein expression in both breast cancer cell lines. Furthermore, elevated Ca2+(o) and the polycationic CaR agonists, neomycin and spermine, stimulated PTHrP secretion dose dependently, with maximal, 2.1- to 2.3-fold stimulation. In addition, pretreatment of MDA-MB-231 cells overnight with TGFbeta1 (0.2, 1, or 5 ng/ml) augmented both basal and high Ca2+-stimulated PTHrP secretion. Thus, in PTHrP-secreting breast cancers metastatic to bone, the CaR could potentially participate in a vicious cycle in which PTHrP-induced bone resorption raises the levels of Ca2+(o) and TGFbeta within the bony microenvironment, which then act in concert to evoke further PTHrP release and worsening osteolysis.

Blotting, Northern↗
PubMed2000

Prediction of bone mass change after parathyroidectomy in patients with 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 NIH has proposed guidelines for the indication of surgery. In the present study, changes in bone mineral density (BMD) after PTX were compared between pHPT patients who did and did not meet the NIH criteria, and we further tried to predict the BMD change after PTX from preoperative parameters. The subjects were 44 pHPT patients (30 women and 14 men) who had had successful PTX. Lumbar and radial BMD were measured before and 1 yr after PTX by dual energy x-ray absorptiometry and single photon absorptiometry, respectively. Average annual percent increases in lumbar and radial BMD after PTX were 12.2 +/- 1.4% and 11.6 +/- 1.6% (mean +/- SEM), respectively, and those net increases were 0.0803 +/- 0.0008 and 0.0484 +/- 0.0006 g/cm2, respectively. There were no significant differences in percent or net changes in either radial or lumbar BMD after PTX between the groups divided according to each of the NIH criteria, such as age (> or =50 and <50 yr), serum calcium level (> or =12 and <12 mg/dL) or the existence of urinary stones (presence and absence). On the other hand, when the subjects were divided on the basis of radial BMD (above and below a z-score of -2), the annual percent and net increases in lumbar BMD and percent increase in radial BMD after PTX were significantly higher in the group with the lower z-score. Next, patients were divided into two groups with and without the indication of PTX based on NIH guidelines. Twenty-nine patients had the surgical indication by meeting one or more of these criteria and 15 patients had no indication without meeting any of the criteria. There were no significant differences between the two groups in annual percent or net changes in radial or lumbar BMD after PTX. A stepwise multiple regression analysis revealed that serum alkaline phosphatase level and the severity of cortical bone mass reduction were the best predictors of both percentage and net changes in lumbar BMD, with high determination coefficients (r2 > 0.7). In conclusion, a considerable increase in BMD could be obtained after PTX even in patients without surgical indication from the NIH. Alkaline phosphatase 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.

Alkaline Phosphatase↗
PubMed2000

Stimulatory effect of procaine on the growth of several microalgae and cyanobacteria.

Procaine has been used to stimulate plant growth and it has been noted that it also promotes growth of microorganisms. The effect of procaine hydrochloride concentration on the growth rates of several species of microalgae and cyanobacteria was studied under both photoautotropic and heterotrophic growth conditions. Procaine hydrochloride was added to cultures at concentrations over the range 0.01-1000 mg L(-1). A stimulating effect of procaine hydrochloride on photoautotrophic growth was observed for the cyanobacteria Anabaena cylindrica and Anabaena variabilis, and for the salt-tolerant green algae Dunaliella primolecta and Dunaliella parva. During active growth in batch culture an increase in growth rate (compared with control culture without procaine hydrochloride) of about 25% was observed at 0.1 mgL(-1) of procaine hydrochloride for A. cylindrica. However, procaine hydrochloride was toxic at concentrations of > 10 mgL(-1). Simultaneous administration of hydrolysis products of procaine, p-aminobenzoic acid and diethyl aminoethanol, in lieu of procaine hydrochloride, was as effective as procaine in stimulating growth of A. cylindrica. Heterotrophic growth of Chlorella ellipsoidea and Prototheca zopfii was not stimulated by procaine hydrochloride over the concentration range studied (0.1-10 mg L(-1)). The combined effects of procaine hydrochloride concentration and four other environmental factors (temperature, light intensity, CO2 concentration in the flushing gas and NaCl concentration) on growth rate of D. primolecta was modelled using both a neural network approach and a response surface method. These results indicate that procaine hydrochloride exerts different effects on the growth of microalgal and cyanobacterial cells as functions of dosage, species and culture conditions.

Anesthetics, Local↗
PubMed2000

Effect of iron(III) chitosan intake on the reduction of serum phosphorus in rats.

Because of the widespread use of aluminium- and calcium-containing phosphate binders for the control of hyperphosphataemia in patients with end-stage renal failure, an iron(III) chitosan complex was synthesised and fed to rats to measure its effect on serum phosphorus and calcium, intestinal phosphate binding and phosphate absorption. Thirty-six Wistar rats were randomly selected and distributed into a baseline group (n = 6), a control group (n = 8 (days 0-15), n = 8 (days 16-30)) and a treatment group (n = 8 (days 0-15), n = 8 (days 16-30)). The control groups ingested AIN-76 diet mix with a 1% w/w fibre content; however, the treatment groups had the fibre content completely substituted with iron(III) chitosan. The mean weights of the treated rats were slightly lower from 15 days (not significant); but overall, rat growth was not stunted in the treatment groups. The serum phosphorus levels of the treated group (n = 8) were significantly reduced after 15 days (P = 0.004; control: 5.7+/-0.9 mg dL(-1); treatment: 4.4+/-0.5 mg dL(-1); 95% CI of difference: 0.5-2.2) and 30 days (P = 0.002; control: 5.5+/-0.9 mg dL(-1); treatment = 4.1+/-06 mg dL(-1); 95% CI of difference: 0.6-2.3) as compared with the respective control group. The serum calcium-phosphorus product was 62.0+/-12.1 mg2 dL(-2) for the control and 45.1+/-6.6 mg2 dL(-2) for the treatment group after 30 days (P = 0.004). The serum iron concentration of the treatment group did not differ from the baseline value after 15 and 30 days, but the treatment group was significantly higher than the control group (P<0.05) after 30 days. The faeces phosphorus levels (mg day(-1)) were higher (P<0.01) and its iron content was much higher (P<0.01) for the treated group. The urine phosphorus (mg kg(-1)) was not significantly reduced for the treated group, but the mean was consistently less. The kidney and liver weights of both groups were similar, but the phosphorus content of the kidney (mg (g kidney)(-1)) was higher for the treated group after 30 days (P = 0.041; control, 4.2+/-1.2 mg g(-1) vs treatment, 5.6+/-1.4 mg g(-1). Because iron(III) chitosan had a high phosphorus-binding capacity of 308 (mg P) per gram of Fe3+ for both the in-vitro (pH 7.5) and in-vivo studies, which is greater than nearly all commonly used phosphate binders, and a small net phosphorus absorption difference of 3.7 mg day(-1), it is an efficient phosphate binder for lowering serum phosphate levels without increasing serum calcium levels.

Animals↗
PubMed2000

Phorbor myristate acetate induces NADPH oxidase activity of cytochalasin B-primed neutrophils through the protein kinase C-independent pathway.

We examined the effect of cytochalasin B (CB) or granulocyte colony stimulating factor (GCSF) on superoxide radical (O2-) production of neutrophils by phorbor myristate acetate (PMA)-stimulation. It was observed that O2- generation of intact and GCSF-treated neutrophils by PMA-stimulation showed a lag during the early stage, and was largely inhibited by 1-(5-isoquinoline-sulfonyl)-3-methyl-piperazine (200 microm) or GF109203X (GFX) (0.2 microM), but not by ethanol (1%) and wortmannin (100 nM). In contrast, O2- generation of CB-pretreated neutrophils by PMA-stimulation did not show a lag, but was less than that of intact cells, and was only minimally depressed by the above inhibitors, but was markedly depressed by the simultaneous addition of GFX and ethanol or GFX and wortmannin. Although translocation of p47phox and p67phox to the membrane fraction by PMA-stimulation of intact and GCSF-treated neutrophils occurred in parallel with O2- production, that of CB-treated neutrophils by PMA-stimulation was not always proportional to O2- production. These findings suggest that pretreatment of neutrophils with CB dramatically alters the PMA response of the cells; that is, the protein kinase C-dependent pathway is largely depressed, and a phospholipase D-dependent one for NADPH oxidase activation appears in CB-treated cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2000

Nucleotide sequence specificity in DNA cleavage caused by dihydropyrazines, a new type of DNA strand-cleaving agent.

The specificity of the nucleotide sequence of DNA strand cleavage sites produced by dihydropyrazines, a new type of DNA strand-cleaving agent, was studied. Biotin-5'-end-labeled PCR-amplified DNA restriction fragments of different defined nucleotide sequences were prepared from plasmid pBR322, and reacted with dihydropyrazines in the presence of Cu2+. After being heated with aqueous piperidine, the DNA products were analyzed on polyacrylamide gels. The most preferentially cleaved sites induced by dihydropyrazines were at purine/pyrimidine-guanine (5' --> 3') sequences. The purine/pyrimidine-adenine, pyrimidine-pyrimidine and purine-pyrimidine (5' --> 3') sequences were more resistant to attack by these dihydropyrazines. The side chains of the dihydropyrazine skeleton greatly affected the DNA strand-cleaving activity, and also, to some extent, the nucleotide sequence-specificity in the DNA strand-cleavage.

Base Sequence↗
PubMed2000

[1-11C]Octanoate as a PET tracer for studying ischemic stroke: evaluation in a canine model of thromboembolic stroke with positron emission tomography.

Octanoate is taken up by the brain and converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. Consequently, [1-11C]octanoate might serve as a useful positron emission tomography (PET) probe for studying cerebral oxidative metabolism and/or astroglial functions. The present study attempted to evaluate the utility of using [1-11C]octanoate as a PET tracer for imaging and evaluating the pathophysiology of ischemic stroke. We used a canine model of thromboembolic stroke. Five male beagle dogs were implanted with an indwelling catheter in the left internal carotid artery. A single autologous blood clot was injected into the left internal carotid artery through the catheter. The brain distribution of [1-11C]octanoate and cerebral blood flow (CBF) were determined 24 h after insult using a high resolution PET scanner. Post mortem brain regions unstained with 2,3,5-triphenyltetrazolium chloride (TTC) were defined as infarcts. In the region of an infarct, accumulation of [1-11C]octanoate decreased concurrently with CBF reduction. In contrast, normal accumulation of [1-11C]octanoate was observed in ischemic but vital regions, suggesting that an increased accumulation of [1-11C]octanoate relative to CBF takes place in these regions. In conclusion, [1-11C]octanoate accumulated in ischemic but vital regions, indicating that [1-11C]octanoate is a potentially useful PET tracer for imaging and evaluating the pathophysiology of ischemic stroke.

Animals↗
PubMed2000

Synthesis, conformation, and chemical properties of new mini parallel double-stranded peptides conjugated with -Phe-Phe- and -Phe-Phe-X-sequences.

To investigate the chemical conformations and functions of the -Phe-Phe-Val- or -Phe-Phe- sequences contained in the Alzheimer's disease related beta-amyloid peptide, a series of mini parallel double-stranded peptides conjugated with two peptide residues to one spacer were designed and prepared. The structure of the compounds was elucidated by circular dichroism (CD) spectrum and NMR two dimensional (2D) nuclear Overhauser enhancement and exchange spectroscopy (NOESY) measurments. The structure of 1,2-ethano-bis(L-Phe-L-Phe-L-Leu), 1,12-dodecano-bis(L-Phe-L-Phe-L-Leu), 1,12-dodecano-bis(L-Phe-L-Phe-L-Val), and 1,12-dodecano (D-Phe-D-Phe-D-Leu) conjugated with L-Leu and L-Val residues show a beta-turn-like nucleation. The dihedral angles (theta = +75 degrees, omega = +180 degrees, phi = +90 degrees, phi = -87 degrees, psi = +180 degrees) obtained from experimental coupling constant (J) data, etc. support that 1,12-dodecano-bis(L-Phe-L-Phe) adopts beta-turn mimic nucleation. The 1,12-dodecano- bis(L-Leu-L-Leu-L-Phe), 1,12-dodecano-bis(L-lle-L-Phe-L-Leu), and 1,12-dodecano-bis(L-Phe-L-Val-L-Leu), etc. adopt most probably a random structure by CD studies. It was found by titration spectrum that an inclusion complex of 1:1 ratio (association constant; azobenzene (guest, Ka=1.0 x 10(4)M-1) is formed between 1,12-dodecano-bis(L.-Phe-L-Phe-L-Leu) and [L0]=1.758 x 10(-5)M-1). Moreover, the stability of the complexes was increased in order of 1,12-dodecano-bis(L-Phe-L-Phe-L-Leu) x azobenzene> 1,12-dodecano-bis(L-Phe-L-Phe-L-Val) x azobenzene> 1,12-dodecano-bis(L-Phe-L-Val-L-Leu) azobenzene. The data show that X-Phe-L-Phe-L-spacer(S)-L-Phe-L-Phe-X (X=amino acids; S = 1,2-ethano- and 1,12-dodecano-) plays an important role as a binding site of the artificial receptor. The hydrophobic interaction of the four Phes in the two strands is a very interesting issue in the physiological action of proteins as well as the conformation of the backbone of X-L-Phe-L-Phe-spacer(S)-iL-Phe-l.-Phe-X.

Amyloid beta-Peptides↗
PubMed2000

Atrial double potentials associated with the elimination of the electrical connection between the coronary sinus (CS) and the left atrium in two cases of Wolff-Parkinson-White syndrome with a CS-connected accessory pathway.

A curious retrograde conduction in connection with the coronary sinus (CS) musculature was observed in 2 patients. After the failed ablation procedure, the atrial electrogram during ventricular pacing presented double potentials, the first component of which was sharp and with an activation sequence that was the same before ablation (CS distal to proximal). The second component of the double potentials was dull and had a decremental property; its activation sequence was in reverse (proximal to distal). In both cases, the first component disappeared after successful ablation. These findings suggest that the first component was the CS electrogram conducted over the accessory pathway and the second component was the left atrial electrogram conducted through the inter-atrial septum. The separation of each electrogram is probably the result of a block between the accessory pathway connected to the CS musculature and the left atrium. These are unusual cases of an accessory pathway connected to the CS musculature, which separates the left atrial myocardium at the distal portion from the ostium.

Adult↗
PubMed2000

Regulation by organic acids of polysaccharide-mediated microbe-plant interactions.

A polysaccharide flocculant of Klebsiella pneumoniae H12 has been suggested to mediate microbe-plant interactions with the aid of Ca2+ [K. Nakata et al., Biosci. Biotechnol. Biochem., 64, 459-465, 2000]. Here, two-way regulation of polysaccharide-mediated interactions between K. pneumoniae and Raphanus sativus was studied using organic acids. Namely, 10 mM equivalents of organic acids promoted production of the polysaccharide by the bacterium, but inhibited flocculation of bacterial cells by the polysaccharide. These phenomena were counterbalanced by equi-molar equivalents of Ca2+, suggesting competition for Ca2+ between the carboxylic residues of the polysaccharide and those of the aliphatic acids. By electron microscopy observations, bacterial cell aggregates were sparsely distributed over the main roots and root hairs, had various sizes, and seemed to tightly adhere to root tissues. Their shapes seemed to be distorted and abundant in cavities. In brief, these microscopical observations may be explained by a two-way regulation system of bacterial adhesion to a plant by organic acids.

Acids↗
PubMed2000

Tyrosine-kinase dependent TGF-beta and extracellular matrix expression by mechanical stretch in vascular smooth muscle cells.

Vascular hypertrophy, which is characterized by proliferation of vascular smooth muscle cells (VSMC) and accumulation of extracellular matrix (ECM), is a major pathological change in blood vessels after chronic exposure to hypertension. Blood pressure is transmitted to the arterial walls and counterbalanced by mechanical stress, leading to stretching of circumferentially oriented VSMC, which may play some role in the pathogenesis of vascular hypertrophy. The present study was designed, therefore, to investigate the effect of mechanical stretch on the expression of ECM components and transforming growth factor-beta (TGF-beta), a potent stimulator for ECM production, and to examine the signal transduction mechanisms of the induction of TGF-beta in cultured rat VSMC. VSMC were subjected to cyclic stretch to provide a maximal elongation of 20% at a rate of 60 cycles per minute for up to 24 h. Mechanical stretch stimulated TGF-beta1 mRNA expression in a time- and elongation-dependent manner. Indeed, the secretion of TGF-beta proteins into the culture media was increased after stretch. Stretch also stimulated mRNA expression of the ECM components, type I and type IV collagen, and fibronectin, which was largely inhibited by addition of neutralizing antibody against TGF-beta. The tyrosine kinase inhibitors genistein and herbimycin A blocked the induction of TGF-beta1 and type I collagen by stretch, while protein kinase C inhibitors, the calcium channel blockers nitrendipine and gadolinium, or Ca removal from the media had no effect. These results suggest that stretch-induced, tyrosine kinase-mediated autocrine/paracrine production of TGF-8 may play a critical role in the progression of vascular remodeling associated with high blood pressure.

Animals↗
PubMed2000

Comparative analysis of the putative amino acid sequences of chlamydial heat shock protein 60 and Escherichia coli GroEL.

The nucleotide sequences of the gene encoding chlamydial heat shock protein 60 (cHSP60) of 7 Chlamydia psittaci strains were determined. Comparison of sequences of the cHSP60 gene among chlamydiae showed high identities of the nucleotide sequences by 81.0% or greater and of the deduced amino acid sequences by 92.2% or greater. Comparison of the amino acid sequences between chlamydia and the other bacterial HSP60s resulted in the finding of three highly conserved regions, suggesting that these regions play a role in some function. In addition, 26- or 27-functional residues in the Escherichia coli GroEL out of the 28-residues are conserved in the amino acid sequences of the cHSP60. The data suggest that the function of the cHSP60 may be the same as that of the E. coli GroEL.

Amino Acid Sequence↗
PubMed2000

Evaluation of changes in bone density and biochemical parameters after parathyroidectomy in primary hyperparathyroidism.

We examined the relationships between serum levels of intact parathyroid hormone (PTH) and alkaline phosphatase (ALP) versus bone mineral density (BMD) at the lumbar spine and radius in terms of their preoperative values and of their annual percentage and net changes after parathyroidectomy (PTX) in 44 Japanese patients (14 men and 30 women) with primary hyperparathyroidism (pHPT). Lumbar and radial BMD values were measured by dual energy X-ray absorptiometry and single photon absorptiometry and were used for evaluating the cancellous and cortical bone mass, respectively. Age- and sex-adjusted value (Z-score) of the radial BMD was significantly lower than that of the lumbar BMD before and after PTX (P < 0.05). In preoperative patients, serum levels of both intact PTH and ALP were significantly and negatively correlated with Z-score of the radial BMD (P < 0.05 and P < 0.001, respectively), but not with that of the lumbar BMD. After PTX, serum levels of calcium, phosphorus, ALP, and PTH became normal, and both lumbar and radial BMD values markedly increased over 1 year, with percentage changes of 12.2+/-1.4% and 11.6+/-1.6%, respectively, which were larger than those in any other Caucasian study previously documented. Even in patients without osteopenia (Z-score of BMD 20), lumbar and radial BMD values increased considerably after the operation (9.6+/-1.9% and 6.7+/-1.4%, respectively). Annual percentage and net changes in lumbar BMD were significantly and negatively correlated with those in ALP with high correlation coefficients, but those in radial BMD were correlated only with the annual net change in ALP but not with the percentage change. No significant correlations were observed between annual changes in either lumbar or radial BMD and those in intact PTH. Taken together, this study shows that PTX causes dramatic improvements in both the cancellous and cortical bone mass in Japanese pHPT patients regardless of the severity of their osteopenia, and suggests that the cancellous and cortical bones react differently to a preoperative endogenous PTH excess and a high bone turnover rate as well as to the postoperative normalization of a bone turnover rate in the patients.

Alkaline Phosphatase↗