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Biomedical subjects

S Miyoshi

Publications and source records attributed to S Miyoshi.

At least 73 records · Page 4Linked to original sources
PubMed2000

Anisotropic conduction prolongs ventricular repolarization and increases its spatial gradient in the intact canine heart.

The effects of the activation sequence on ventricular repolarization and its spatial gradient were examined in anesthetized open-chest dogs. Unipolar and bipolar electrograms were recorded from 47 epicardial sites on the anterior left ventricular wall using a mapping electrode. The local QT interval (QT) and the activation time (AT) at each site were measured on the unipolar and bipolar electrograms, respectively. The QT index (QTI) was defined as the QT minus AT interval, and was used as a measure of local repolarization. QTI was longer at each site during propagation that was longitudinal (L) (219+/-21 ms) than during propagation transverse (T) (202+/-22 ms, p<0.001) to the epicardial fiber orientation or during atrial pacing (165+/-20 ms, p<0.001). During L-propagation, the QTI shortened as a function of the distance from the stimulus. The spatial gradient was steeper during T-propagation (p<0.05). Monophasic action potentials (MAP) were also recorded simultaneously at 4 epicardial sites. The MAP duration during ventricular pacing was longer than during atrial pacing at sites within 1.5 cm of the pacing site. This difference disappeared at more distant sites and was attenuated by a simultaneous stimulus from a site symmetrically aligned along the fiber. These findings indicate that anisotropic conduction prolongs ventricular repolarization and increases its spatial gradient in the intact heart. An electrotonic downstream effect appears to be the cause.

Animals↗
PubMed2000

Hydrolysis of beta-glucosyl ester linkage of p-hydroxybenzoyl beta-D-glucose, a chemically synthesized glucoside, by beta-glucosidases.

To investigate the hydrolysis of glucosyl esters by beta-glucosidase, p-hydroxybenzoyl beta-D-glucose (pHBG) was chemically synthesized. The hydrolytic activity of some beta-glucosidases for pHBG was compared to that for p-nitrophenyl beta-glucoside (pNPG). The Clavibacter michiganense and Flavobacterium johnsonae enzymes could hydrolyze pHBG and steviol glycosides which are natural glucosyl esters. The commercial beta-glucosidase originating from Caldocellum saccharolyticum also hydrolyzes pHBG despite having no activity for steviol glycosides. The beta-glucosidase from Aspergillus niger cleaved the glucosyl ester linkage much more weakly than the glucosidic linkage. The pH-activity profile for the hydrolysis of pHBG was similar to that of pNPG by the C. saccharolyticum beta-glucosidase. The similar profiles for these substrates suggested that the active site for the glucosyl ester chemically resembles that for glucoside with respect to catalysis. Kinetic analysis of the C. saccharolyticum beta-glucosidase for mixed substrates of pHBG and pNPG showed that the hydrolysis of pHBG competed with that of pNPG. This result indicated that there is only one active site for both the glucosyl ester and glucoside. Mass spectroscopic analysis of the hydrolysates of pHBG in H218O suggested that beta-glucosidase hydrolyzes glucosyl esters between the anomeric carbon of glucose and the carbonyl oxygen, not between the carbonyl carbon and the carbonyl oxygen.

Journal Article↗
PubMed2000

Intrapleural administration of a large amount of diluted fibrin glue for intractable pneumothorax.

OBJECTIVE: Pleurodesis using chemical agents has been applied to high-risk patients with pneumothorax. This treatment, however, is sometimes unsuccessful in patients with intractable pneumothorax or intrapleural dead space. We developed a technique for the intrapleural administration of diluted fibrin glue as a treatment for such patients. METHODS: Fibrin glue was diluted fourfold with saline solution and/or contrast medium. Pleurodesis with a large amount of the diluted fibrin glue was performed in 40 high-risk patients with intractable pneumothorax and in 13 postthoracotomy patients with persistent air leakage associated with an intrapleural dead space. RESULTS: The air leaks were stopped by administration of the glue in all patients of both groups. During the follow-up period, a recurrence rate of 12.5% was observed in the former group. These recurrent pneumothoraces also were successfully treated by glue administration with no further recurrence. In the 13 postthoracotomy patients, there was no recurrence after the initial treatment. Pyrexia (12.5%) and chest discomfort (4.1%) were observed as side effects, but there were no findings of severe chest pain or thoracic empyema. CONCLUSIONS: These results suggest that intrapleural administration of a large amount of diluted fibrin glue is a useful treatment for intractable pneumothoraces in high-risk or postthoracotomy patients who have an intrapleural dead space.

Adult↗
PubMed2000

Exercise capacity of thoracotomy patients in the early postoperative period.

OBJECTIVE: We investigated the mechanism involved with the initial drop and subsequent recovery of exercise capacity in the early postoperative period of thoracotomy patients. METHODS: Sixteen patients (13 who had undergone lobectomy, 3 who had undergone pneumonectomy) underwent a routine pulmonary function test (PFT) and a cardiopulmonary exercise test preoperatively, within 14 postoperative days (POD; post-1; mean +/- SD, 9 +/- 2 POD), and after 14 POD (post-2; mean, 26 +/- 12 POD). RESULTS: After surgery on post-1, PFT results of FVC, FEV(1), and maximum ventilatory volume (MVV) significantly decreased. Oxygen uptake (VO(2)) at a venous blood lactate level of 2.2 mmol/L (La-2. 2), which was adopted as the empirical anaerobic threshold, and maximum V O(2) (VO(2)max) decreased significantly to 88.2 +/- 7.9% and 73.1 +/- 15.4% of the preoperative values, respectively. La-2.2 min ventilation (VE)/ MVV and maximum VEmax)/MVV increased significantly from 0.36 +/- 0.08 to 0. 66 +/- 0.20 and from 0.58 +/- 0.14 to 0.80 +/- 0.09, respectively. On post-2, though La-2.2 VO(2) did not change, VO(2)max improved significantly to 81.5 +/- 19.7% of the preoperative values, in association with significant increases in maximal tidal volume and VEmax, which were produced by significant increases in the PFT results. La-2.2 VE/MVV also decreased significantly to 0.49 +/- 0.13, which indicated a sufficient recovery of respiratory reserve at submaximal exercise. CONCLUSIONS: The initial drop of exercise capacity after lung resection seems to be derived from both circulatory and ventilatory limitations. Further, the subsequent recovery within 1 month seems to be produced by an improvement in ventilatory limitation, which was caused by the surgical injury to the chest wall.

Adaptation, Physiological↗
PubMed2000

Prediction of crude fat content of longissimus muscle of beef using the ratio of fat area calculated from computer image analysis: comparison of regression equations for prediction using different input devices at different stations.

Crude fat content of longissimus (ribeye) muscle of beef cattle was predicted from a ratio of fat area (RFA) to area of ribeye muscle calculated from computer image analysis (CIA). Cross sections of 64 ribeyes taken from the 6-7th rib from cattle at experiment station A and cross sections of 94 ribeyes taken from the 6-7th rib from cattle at Experiment Station B were used in this study. Slices (1 to 1.5 cm in thickness) of just the Longissimus dorsi were homogenized and sampled for chemical estimation of crude fat content using petroleum ether. Crude fat content as determined from chemical analysis was used as the true estimate of fat content. A CCD (charge-coupled device) camera was used as the input device at Experiment Station A, and a single-lens reflex camera was used at Experiment Station B to photograph ribeyes for CIA. The contour comparison method, which assigns a threshold value for each marbling particle, was used to obtain accurate binarization in this study. Minimum and maximum of chemical measurements of crude fat were 2.1 and 39.8%, and for CIA calculation of the RFA were 6.1 and 56.8%, respectively. This range covered almost the complete range of the beef marbling standard used in carcass grading in Japan. The equation for the regression of the crude fat content (Y) on RFA (X) calculated from CIA for all of the data was Y = .793X-3.04 with r2 = .96. Regression equations for prediction of crude fat percentage from RFA taking into consideration the effect of experiment station were Y = .741X-2.22 with r2 = .91 for Experiment Station A, and Y = .782X-2.54 with r2 = .91 for Experiment Station B. Analysis of covariance showed that the effects of experiment stations on intercepts and slopes were not significant (P > .10). The ranges of differences between actual and predicted crude fat content from the prediction equation that was calculated without consideration of the effect of station were -6.4 to 4.0%. CIA of cross sections of the ribeye muscle seems to have potential for prediction of crude fat content.

Adipose Tissue↗
PubMed2000

[Intrascrotal lipoma: a case report].

A 72-year-old male was admitted to our hospital with the complaint of right painless swelling of extratesticular scrotal content. Laboratory examinations were unremarkable. Under the diagnosis of an intrascrotal lipoma, the tumor was resected. The removed specimen weighed 115 g. Histopathological findings revealed lipoma. Other cases from the Japanese publications, together with our case, are reviewed.

Aged↗
PubMed2000

[Primary transitional cell carcinoma of prostate: a case report].

A 67-year-old male was admitted with a three-month history of voiding difficulty. Prostate specific antigen remained within the normal limit. Under the diagnosis of benign prostatic hypertrophy, transurethral resection of prostate was performed. Pathological examination of the resected specimens of the prostate revealed transitional cell carcinoma. Two courses of systemic M-VAC (methotrexate, vinblastine, doxorubicin, cisplatin) chemotherapy were performed, followed by cystoprostatourethrectomy, pelvic lymphadenectomy, and ileal conduit construction. Now one year has elapsed, with no clinical signs of recurrence.

Aged↗
PubMed2000

[Metastatic bladder tumor disseminated lymphogenously from gastric cancer: a case report].

A 59-year-old man was referred to our clinic with a complaint of frequent urination, voiding pain, and macroscopic hematuria. He had undergone total gastrectomy for mucinous adenocarcinoma, 21 months earlier. Pelvic computed tomography revealed a thick bladder wall all around. There were no other metastatic sites except for paraaortic lymph nodes. Transurethral resection of the bladder tumor was performed. The specimen showed signet ring cell carcinoma and revealed the same pathological findings as the primary gastric cancer. We diagnosed him with metastastic bladder tumor lymphogenously disseminated from gastric cancer. Such lymphogenous metastases from gastric cancer at the entire bladder wall without other apparent lesions have rarely been reported in the Japanese literature.

Adenocarcinoma, Mucinous↗
PubMed2000

[A patient with motor neuron syndrome clinically similar to amyotrophic lateral sclerosis, presenting spontaneous recovery].

We report a patient with motor neuron syndrome similar to amyotrophic lateral sclerosis (ALS) and with spontaneous recovery. At the age 40, the woman developed progressive muscular weakness, atrophy and fasciculation in extremities. She also noted a dyspnea, tongue atrophy and dysphagia. A neurological examination 6 months after onset revealed i) a tongue atrophy and fasciculation, ii) diffuse muscule weakness and atrophy in face, neck and extremities, and iii) marked hyperreflexia in the four limbs and bilateral Babinski reflex, but iv) neither sensory disturbance nor ophthalmoplegia. Electromyogram (EMG) detected such denervation potentials as fibrillation potentials, fasciculation potentials, positive sharp waves and polyphasic or giant MUPs diffusely in the limb muscles. Peripheral nerve conduction study detected neither conduction block nor delay. Thus, she was diagnosed as suffering from ALS. However, since approximate 1 year after onset, her muscle weakness has gradually been getting better. Simultaneously, the dyspnea and dysphagia gradually improved. Two years after onset, an EMG examination detected chronic denervation potentials in the left musculus sternocleidomastoideus and a few on-going denervation potentials in the left musculus extensor carpi radialis, but no denervation potentials in other limb muscles. Fasciculation potentials were found in tongue muscles. Thus, the present case was thought to have a reversible motor neuron syndrome clinically quite similar to ALS. A mild increase in IgE (346 U/ml) and a low-titer IgM-class anti-GM1 antibody were found in her serum though its pathological significance was uncertain. Any immunological aberrance may account for the pathogenesis. It should be noted that clinically diagnosed cases of ALS may rarely recover spontaneously.

Adult↗
PubMed1999

Muscarinic acetylcholine receptor (mAChR) inhibitor from snake venom: interaction with subtypes of human mAChR.

Snake venoms can contain a variety of well-studied neurotoxins, especially nicotinic acetylcholine receptor inhibitor, normally called postsynaptic neurotoxin. Karlsson first reported muscarinic acetylcholine receptor (mAChR) inhibitor from snake venom. In a previous study in our laboratory, we found a mAChR inhibitor from Naja naja sputatrix venom that bound to rat brain synaptosomes. Brain synaptosomes contain all subtypes of mAChRs, and thus the exact selectivity of the inhibitor could not be determined. mAChR inhibitor from N. naja sputatrix venom was purified and the binding to all human mAChR subtypes (M1, M2, M3, M4, and M5) was investigated and is reported in this communication. The inhibitor bound to all subtypes of the human mAChR, but showed considerably high selectivity for the M5 subtype. It was also found that the reduction of disulfide bonds in the inhibitor eliminated the binding to the mAChR. This suggests that a specific tertiary conformation maintained by disulfide bonds is essential for binding to the mAChR. An oligo peptide, QIHDNCYNE, comparable to a part of the inhibitor molecule, was synthesized and studied for its binding to the mAChR. The synthetic peptide did not show any binding activity, suggesting this portion of the inhibitor molecule is not involved in mAChR binding. The selective binding of the M5 mAChR subtype to antagonists has not yet been reported. Therefore, the purified inhibitor reported in this communication may be a useful tool to clarify the mechanism of muscarinic cholinergic transmission.

Amino Acid Sequence↗
PubMed1999

Nitric oxide production by bronchoalveolar cells during allograft rejection in the rat.

BACKGROUND: We reported the increased nitric oxide (NO) level in exhaled air of rat lung transplant recipients during acute rejection (AR). The aim of this study was to determine the site and level of NO production in the rejected graft. METHODS: Rat lung transplantation was performed in isografts and allografts. RESULTS: In isografts, no AR and no significant increase in NO production was identified. In allografts, grades I-II of AR was seen on postoperative day (POD) 3 and grade III on POD 5. NO produced by BAL cells increased on both POD 3 (11.8+/-2.0 parts per billion [ppb]) and POD 5 (115.3+/-66.9 ppb). There was a highly significant correlation between the level of NO and the severity of AR (p=0.862, P<0.005). BAL cells from allografts expressed iNOS mRNA. Among them, macrophages, lymphocytes and neutrophils were immunostained for iNOS. CONCLUSION: NO produced by BAL cells was detected in the early stages of rejection. Therefore, it may serve as a sensitive indicator of AR in lung transplantation.

Animals↗
PubMed1999

The ability of Vibrio vulnificus to use a synthetic hydrophilic heme compound, Fe-TPPS, as a single iron source.

Vibrio vulnificus, an opportunistic human pathogen, can obtain iron from a variety of heme proteins. This process involves the digestion of heme proteins by an exoprotease to liberate protoheme (iron-protoporphyrin IX). In the present study, we tested whether this pathogen also uses a synthetic heme compound, Fe-alpha,beta,gamma,delta-tetraphenylporphine tetrasulfonic acid (Fe-TPPS), as an iron source. When inoculated into a medium containing Fe-TPPS, V. vulnificus L-180 multiplication was seen to be dependent on the concentration of the synthetic heme compound; a mutant lacking the ability to utilize protoheme did not multiply. Cells of the strain grown under the iron-restricted condition showed time-dependent uptake of Fe-TPPS. The ability to use either protoheme or Fe-TPPS was significantly reduced by the addition of an excess amount of free TPPS or Cu-TPPS. The data suggest that, V. vulnificus may assimilate Fe-TPPS, at least partially, through the same system as that for protoheme.

Blood↗
PubMed1999

Simple method to isolate the intact duct system of the rat submandibular gland.

The excurrent duct system of the rat submandibular gland consists of a number of distinct segments. Using the direction of salivary flow as a reference point, these segments are, in order, intercalated duct, granular convoluted tubule, striated duct, excretory duct, main excretory duct (MED), and salivary bladder (which is an expanded portion of the MED). Because these ducts (with the exception of the MED and the salivary bladder) are encased in secretory endpieces, they are difficult to locate and to observe by scanning electron microscopy. A simple method has been devised to rid the gland of these obscuring endpieces so that the detailed architecture of the duct system can be examined. Rat submandibular glands were fixed initially by vascular perfusion with half-strength Karnovsky's fixative. The connective tissue capsule was removed from extirpated glands and the glands remained in fixative for varying lengths of time. For our purposes, a 30-minute immersion in the aldehyde mixture was optimum. After the sublingual gland was removed, the submandibular gland was softly struck with forceps having rounded tips, then shaken in fixative or buffer. The tissue that remained was postfixed in osmium tetroxide. This method results in the complete divestment of nonductular parenchyma from the rat submandibular gland, leaving the duct system clean and ready for microscopic examination.

Animals↗
PubMed1999

Modification of expression of stem cell factor by various cytokines.

The local production of stem cell factor (SCF) may be an important mechanism for regulating proliferation, differentiation, and migration of various cells bearing c-kit receptors, and might be susceptible to the cytokines that serve in inflammation and tissue repair. We have demonstrated that in three murine cell lines, Balb/3T3A31, MC3T3-E1, and C3H-2K, which constitutively produced SCF with different quantity, the SCF mRNA expression was greatly enhanced in response to basic fibroblast growth factor (bFGF) or transforming growth factor beta1 (TGF-beta1). The study was carried out by in situ hybridization utilizing nonradioactive oligonucleotide probes and quantitative image analysis. Leukemia inhibitory factor (LIF) or interleukin-4 (IL-4) moderately increased SCF mRNA in all cell lines, but IL-3 did not. The dot-blot enzyme-linked immunosorbent assay (ELISA) further confirmed that SCF protein production in these cell lines and bone marrow stromal cells was markedly enhanced by TGF-beta1, although TGF-beta1 suppressed the proliferation of all these cells. bFGF also enhanced the SCF production in these cell lines, but did not in bone marrow stromal cells, suggesting a difference in their susceptibility to the cytokine. Our results suggest that TGF-beta1 and bFGF potentially modulate the biological function of cells bearing c-kit receptors through the modulation of SCF production in fibroblasts.

3T3 Cells↗
PubMed1999

Leukemia inhibitory factor, a potent cardiac hypertrophic cytokine, enhances L-type Ca2+ current and [Ca2+]i transient in cardiomyocytes.

This study investigates whether leukemia inhibitory factor (LIF), a potent cardiac hypertrophic cytokine, affects the L-type Ca2+ current (I(Ca,L)) and intracellular Ca2+ concentrations ([Ca2+]i) in cardiomyocytes. I(Ca,L) was recorded using a whole cell patch clamp configuration in guinea pig cardiomyocytes, and the [Ca2+]i transient was detected by use of Fluo-3 in rat cardiomyocytes. Cells were preincubated with LIF (1000 U/ml) for 15 min before whole cell recording. LIF increased I(Ca,L) by 41.8%. LIF synergistically increased I(Ca,L) with isoproterenol. Preincubation with H89 did not inhibit the LIF-induced increase in I(Ca,L), indicating that this phenomenon is PKA-independent. PD98059 completely inhibited the increase in I(Ca,L), and this effect was dose-dependent (IC50=3.6 micromol/l). Other signal transduction inhibitors including AG490, SB203580, chelerythrine, genistein, and KN62 did not affect the LIF-induced increase in I(Ca,L). Perforated patch clamp recording revealed that LIF maximally increased the I(Ca,L) by 25% at 15 min. LIF also increased the peak [Ca2+]i transient level by 63% at 15 min. PD98059 fully inhibited the increase in the [Ca2+]i transient. In conclusion, LIF increased I(Ca,L) and the [Ca2+]i transient in cardiomyocytes, and the Raf-1/MEK/ERK pathway might be involved in the modulation of this activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Chest size matching in single and double lung transplantation.

We applied predicted vital capacity to chest size matching between donor and recipient in lung transplantation to 15 single-lung transplant recipients with pulmonary fibrosis and to 20 double-lung transplant recipients with emphysema or non-emphysema. The predicted vital capacity of the donor was significantly correlated with the predicted vital capacity of the recipient both in double-lung transplantation (r = 0.79, p = 0.001) and single-lung transplantation (r = 0.71, p = 0.003). In double-lung transplantation, the post-transplant vital capacity was correlated with the predicted vital capacity of the recipient (r = 0.74, p = 0.002). Emphysema patients and non-emphysema patients contributed equally to this correlation. In left single lung transplantation, there was a weak correlation between the post-transplant vital capacity and the predicted vital capacity of the donor in the allograft (r = 0.57, p = 0.1095). In right single lung transplantation, the post-transplant vital capacity of the allograft tended to be correlated with the predicted vital capacity of recipient (r = 0.77, p = 0.0735). We concluded that donors were actually selected based on the comparison of predicted vital capacity between donor and recipient. In double-lung transplantation, the post-transplant vital capacity was limited by the recipient's normal thoracic volume and was not influenced by underlying pulmonary disease. In single-lung transplantation with pulmonary fibrosis, the allograft transplanted in the left chest could expand to its own size, and the allograft transplanted in the right chest could expand to the recipient's normal thoracic volume as in double-lung transplantation.

Humans↗
PubMed1999

Surgical rescue for life-threatening hypoxemia caused by a mediastinal tumor.

We recently encountered a patient with a large anterior mediastinal tumor who developed severe hypoxemia during general anesthesia. This life-threatening hypoxemia was treated by extracorporeal membrane oxygenation using emergent percutaneous cardiopulmonary support followed by extirpation of the tumor. We found that total arteriovenous shunt resulting from compression by the mediastinal tumor caused this severe hypoxemia (total obstruction of left main bronchus and of the right pulmonary artery).

Adult↗