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Biomedical subjects

M Gotoh

Publications and source records attributed to M Gotoh.

At least 91 records · Page 5Linked to original sources
PubMed2000

Gene expression of procollagen alpha 1 (I) and alpha 1 (III) in partial-thickness tears of the deep pectoral tendon in chickens.

The purpose of this study was to evaluate the healing process of partial-thickness tears of the deep pectoral tendon in chickens which is considered to be equivalent to the human rotator cuff. The superior side (bursal-side) and the inferior side (joint-side) layers of the deep pectoral tendon of 80 adult chickens were lacerated in the same manner. The mRNA expression levels of alpha 1 (I) and alpha 1 (III) procollagen was at a level 2 weeks after laceration. The mRNA expression level of procollagen alpha 1 (I) was significantly higher than that of procollagen alpha 1 (III) in all experimental periods (p<0.05). The expression levels of procollagen-mRNAs were constitutively higher in bursal-side tears than in joint-side tears throughout the experimental periods (p<0.05), even 52nd weeks after laceration. These observations indicate that the bursal-side layer possesses higher healing ability than the joint-side layer in the chicken's deep pectoral tendon where subacromial impingement is absent, and that the remodeling of partial-thickness tears in chicken models needs more than one year.

Animals↗
PubMed1999

Participation of the liver in generation of a vigorous anti-donor response after inoculation of donor spleen cells.

BACKGROUND: There is a general agreement that a preferential accumulation of alloantigens within the liver could induce hyporesponsiveness to the inoculated antigens. Entrapment of antigens in the liver may evoke an unique immune response in the organ and play a key role in determination of the fate of the transplanted grafts. To understand the immune response in the liver after inoculation of allogeneic donor antigens, we examined the immune response to systemically inoculated alloantigen in rats whose sensitized liver was replaced with that of naive rats or in naive rats whose liver was replaced with that of sensitized rats. METHODS: Using implantation of syngeneic liver (alloantigen-accumulated/naive) in rats (naive/alloantigen-sensitized), we compared the immune responses to alloantigen between rats with hepatic/extrahepatic alloantigen at 24 hr after alloantigen inoculation. This was called sensitized-liver-grafted (SLG)/sensitized-liver-removed (SLR) treatment. The immune response to donor alloantigen in this model was evaluated by survival of skin or heart grafts, complement-dependent cytotoxicity (CDC) titer and delayed-type hypersensitivity (DTH) response. RESULTS: Compared with the mean survival time (MST) in donor spleen cell inoculated (DSI) rats (skin and heart, MST: 8.2+/-1.1 and 10.7+/-2.3 days), SLG rats rejected allografts in an accelerated fashion (skin and heart, MST: 5.5+/-0.5 and 4.2+/-0.8 days), associated with higher CDC titer and DTH response. In contrast, allograft survival was moderately prolonged in SLR (skin and heart, MST: 16.5+/-2.6 and 29.5+/-3.7 days) associated with suppressed CDC titer and DTH response. The survival of third-party allograft after SLG or SLR treatment (skin, MST: 9.3+/-1.5 or 9.7+/-0.6 days) indicated that immunological hyper/hyporesponsiveness was donor-specific. CONCLUSIONS: A strong anti-donor immune response was induced by the transfer of donor antigen-baring liver to naive rats 24 hr after alloantigen inoculation, whereas removal of the liver suppressed alloimmune response. Our results indicate that vigorous anti-alloimmune response occurred in the liver after systemic inoculation of donor spleen cells.

Adoptive Transfer↗
PubMed1999

Pretreatment of crude pancreatic islets with mitomycin C prolongs graft survival time in xenogeneic rat-to-mouse model.

BACKGROUND: Rejection of pancreatic islet grafts is still a serious problem. We evaluated the effect of mitomycin C (MMC) on the survival of crude islets grafts after xenogeneic islet transplantation. METHODS: WS (RT1k) rat islets pretreated with various concentrations of MMC (0, 1, 3.2, 10, 32, 50, 100, 320, and 1,000 microg/ml) were transplanted into C57BL/6 mice with streptozotocin-induced diabetes. In vivo graft function was assessed by a daily measurement of nonfasting blood glucose concentration in each animal. We also examined the separate effect of MMC on purified islets and contaminants present in the crude islet preparation. RESULTS: MMC at doses of 10, 32, 50, and 100 microg/ml resulted in a significant prolongation of the mean graft survival time from a control of 12.4+/-2.5 days to 23+/-7.4, 17.5+/-5.4, 25.5+/-14.7, and 26.7+/-8.9 days, respectively. Deterioration of glucose metabolism was noted when the dose exceeded 32 microg/ml, whereas at 320 microg/ ml, MMC failed to restore normoglycemia. Prolongation of survival time of crude islets was the result of its effect on islets and contaminant components of the crude islet preparation. In vitro study showed that MMC treatment at a higher concentration than 10 microg/ml reduces the stimulatory as well as proliferative capacity of lymph node cells. CONCLUSIONS: Pretreatment of pancreatic islets with MMC at 10 microg/ml prolongs xenograft survival without deterioration of in vivo graft function. This novel treatment modality represents a new strategy for the modulation of immunity of islets and contaminants in crude islet preparations.

Animals↗
PubMed1999

Injection of mitomycin-C-treated spleen cells induces donor-specific unresponsiveness to cardiac allografts in rats.

BACKGROUND: In this study, preoperative mitomycin-C- (MMC) treated donor-specific transfusion (DST) was examined for its ability to induce unresponsiveness to cardiac allografts in rats. METHODS: DA (RT1a) rats were used as donors, BUF (RT1b) or WS (RT1k) rats as recipients, and Lew (RT1l) rats as third party donors. BUF or WS rats were given i.v. injection of DA spleen cells (SPCs) suspension (5x10(7)/l ml) with or without MMC treatment 10 days before cardiac transplantation. Delayed-type hypersensitivity and complement-dependent cytotoxicity assays were carried out in these animals separately to examine in vivo immunosuppressive effect. Suppressor assay was also examined to determine in vitro immunosuppressive effects in allogeneic mixed leukocyte culture. RESULTS: In the full allogeneic DA-to-BUF rat strain combination, preoperative i.v. administration of MMC-treated donor SPCs led to a significant prolongation of graft survival over the control (110+/-66 versus 7.2+/-0.8 days: P<0.01), although administration of nontreated donor SPCs did not (9.3+/-1.0 days). This beneficial effect of MMC treatment was also seen in the DA-to-WS rat combination (31+/-16 days versus donor-specific transfusion alone; 11+/-1.5 days or untreated control; 12+/-1.5 days; P<0.05). However, injection of third party DA SPCs in the Lew-to-BUF combination induced no significant prolongation of cardiac allograft survival compared with the untreated control (11+/-0.6 versus 11+/-2.0 days; NS), indicating that this prolongation effect was induced in an antigen-specific manner. The immunosuppressive effect was also secured for both delayed-type hypersensitivity response and anti-donor cytotoxic antibody production. Moreover, addition of MMC-treated SPCs to mixed lymphocyte culture led to antigen-specific suppression. CONCLUSIONS: Preoperative i.v. injection of MMC-treated donor SPCs is promising for inducing unresponsiveness in rat cardiac allograft model.

Adoptive Transfer↗
PubMed1999

Synthesis of novel 2-benzothiopyran and 3-benzothiepin derivatives and their stimulatory effect on bone formation.

In a search for therapeutic agents for the treatment of osteoporosis and bone fracture, we found that 2-benzothiopyran-1-carboxamide derivatives 1, derived from ipriflavone as a lead compound, increase cellular alkaline phosphatase activity in cultures of rat bone marrow stromal cells. Further modification of 1 has led to the discovery of more potent 3-benzothiepin-2-carboxamide derivatives 2. Of these, 3-benzothiepin derivatives bearing a 4-(dialkoxyphosphorylmethyl)phenyl group on the 2-carboxamide moiety such as 2h and 2q exhibited significant improvement of activity compared to ipriflavone. Asymmetric synthesis of 2h and 2q revealed that the (-)-isomers possessed activities superior to those of the (+)-isomers. Further evaluation of these compounds using the mouse osteoblastic cell line MC3T3-E1 revealed that (-)-2q enhanced the effect of bone morphogenetic protein. In addition, application of a sustained-release agent containing 2q increased the area of newly formed bone in a rat skull defect model. Based on these findings, (-)-2q was selected for further investigation as a new drug stimulating bone formation. Synthesis and structure-activity relationships for this novel series of 2-benzothiopyran and 3-benzothiepin derivatives are detailed.

3T3 Cells↗
PubMed1999

Somatostatin induces hyperpolarization in pancreatic islet alpha cells by activating a G protein-gated K+ channel.

Somatostatin inhibits glucagon-secretion from pancreatic alpha cells but its underlying mechanism is unknown. In mouse alpha cells, we found that somatostatin induced prominent hyperpolarization by activating a K+ channel, which was unaffected by tolbutamide but prevented by pre-treating the cells with pertussis toxin. The K+ channel was activated by intracellular GTP (with somatostatin), GTPgammaS or Gbetagamma subunits. It was thus identified as a G protein-gated K+ (K(G)) channel. RT-PCR and immunohistochemical analyses suggested the K(G) channel to be composed of Kir3.2c and Kir3.4. This study identified a novel ionic mechanism involved in somatostatin-inhibition of glucagon-secretion from pancreatic alpha cells.

Acetylcholine↗
PubMed1999

Mechanism of acceleration of functional reentry in the ventricle: effects of ATP-sensitive potassium channel opener.

BACKGROUND: The effect of effective refractory period (ERP) shortening on the vulnerability and characteristics of induced functional reentry in the ventricle remain poorly defined. We hypothesized that ERP shortening increases ventricular vulnerability to reentry and accelerates its rate, as is the case in the atrium. METHODS AND RESULTS: The epicardial surfaces of 19 isolated and superfused canine right ventricular slices (4x4 cm and <2 mm thick) were mapped with 480 bipolar electrodes 1.6 mm apart. Vulnerability was tested during pacing at a cycle length (CL) of 600 ms and with a single premature stimulus of 5-ms duration at increasing current strength of 1 to 100 mA. Cromakalim (10 micromol/L), an ATP-sensitive potassium channel opener, caused a significant (P<0. 001) shortening of the ERP but had no effect on conduction velocity. Cromakalim increased (P<0.01) the vulnerability (product of current and the stimulus coupling interval) for reentry induction. Reentry had a significantly shorter CL and lasted for a longer duration (P<0. 001). The central core around which the wave front rotated became smaller, which caused shortening of the CL of reentry. A significant (P<0.001) linear correlation was found between core size and reentry CL. These effects of cromakalim were reversible. Two-dimensional simulation studies using the modified Luo-Rudy I model of cardiac action potential, in which the refractory period was variably shortened by a progressive increase of the time-independent potassium conductance, reproduced the experimental findings. CONCLUSIONS: ERP shortening by an ATP-sensitive potassium channel opener increases ventricular vulnerability to reentry and accelerates its rate by decreasing the core size around which the wave front rotates.

Action Potentials↗
PubMed1999

Microchimerism in thymus is associated with up-regulated T helper type 1 cytokine transcription during cardiac allograft rejection in rats.

BACKGROUND: Intrathymic microchimerism (MC) is thought to be responsible for inducing allograft tolerance. However, the role of MC in the thymus gland after transplantation, particularly in the rejection response, is unknown. We investigated serial changes in intrathymic cytokine production associated with MC and allograft rejection. METHODS: Donor-specific cell injection (DSI) and heterotopic heart transplantation (HTx) were performed in the fully allogeneic combination using DA rats (RT1a) as donors and WS rats (RT1k)as recipients. MC was checked by polymerase chain reaction (PCR) using a donor RT1.Bbeta domain 1 region sequence-specific primers. Reverse transcription (RT)-PCR analysis of cytokine (interleukin [IL]-2, interferon-gamma, IL-4, and IL-10) profiles of the thymus was performed in animals given DSI, HTx, or DSI/HTx. RESULTS: DSI alone resulted in an immediate development of MC, detected by PCR, in various organs including the thymus, spleen, liver, and blood, of most rats, lasting for over 2 months. However, DSI-induced MC selectively disappeared in the thymus on day 7 after grafting, several days before the rejection of cardiac allograft. RT-PCR analysis of cytokine profiles showed that the levels of Th1 (IL-2 and interferon-gamma) cytokines transcribed in the thymus were higher than in the spleen. MC reappeared in the thymus on day 21 after grafting, but was not associated with elevation of Th1 cytokine transcription when allograft was replaced by fibrosis. CONCLUSIONS: Intrathymic MC does not always confer unresponsiveness to alloantigen, but can be eliminated after anti-donor response.

Animals↗
PubMed1999

Increased interleukin-1beta production in the synovium of glenohumeral joints with anterior instability.

Macroscopic synovitis of the glenohumeral joint is frequently seen during arthroscopy in patients with anterior instability. Interleukin-1beta is known to be expressed in inflamed tissue, to correlate with the magnitude of inflammation, and to affect articular cartilage in the joint. We hypothesized that chronic synovitis may occur in the glenohumeral joint in patients with anterior instability. The purpose of this study was to examine the expression of interleukin-1beta in the synovium of the glenohumeral joint with anterior instability and to discuss its clinicopathologic significance. Specimens of synovial tissue around the greater tuberosity in the subacromial synovium (as controls) and around the rotator interval in the glenohumeral synovium were obtained from 10 patients who had anterior instability without signs of subacromial impingement. Semiquantitative reverse transcriptase-polymerase chain reaction was used to compare the levels of interleukin-1beta mRNA expression in the glenohumeral joint with those in the subacromial bursa. We also employed immunohistochemistry and in situ reverse transcriptase-polymerase chain reaction to detect the cells producing interleukin-1beta protein and mRNA. The levels of interleukin-1beta mRNA expression were significantly higher in the glenohumeral joint than in the subacromial bursa (p < 0.01). Histology showed nonspecific inflammation in all 10 samples of glenohumeral synovium, whereas no inflammation was seen in seven of 10 samples of subacromial synovium. Immunohistochemistry identified interleukin-1beta protein in the vessels and inflammatory and synovial cells (from lining to sublining layers) in synovium of the glenohumeral joint, whereas immunoreactivity was negative in seven subacromial bursa. The remaining three synovial specimens of subacromial bursa, however, showed positive immunoreactivity that was unremarkable and confined around the vessels. In situ reverse transcriptase-polymerase chain reaction was exclusively performed in the synovial specimens of the glenohumeral joint, which exhibited a positive reaction (in the same kinds of cells as seen with immunohistochemistry) in the lining and sublining layers and to a lesser extent in the stroma. Thus, our data confirmed the increased production of interleukin-1beta in the synovium of the glenohumeral joint in patients with anterior instability, suggesting the presence of chronic inflammation at the site. We conclude that this chronic synovitis may be partly associated with the development of dislocation arthropathy in the long term.

Acromion↗
PubMed1999

Positive bladder cooling reflex in patients with bladder outlet obstruction due to benign prostatic hyperplasia.

The bladder cooling reflex was evaluated in patients with bladder outlet obstruction to study the effect of obstruction on the afferent neural function of the bladder, especially on the C-afferents. The bladder cooling test was performed by infusion of 0 degree C saline into the bladder with simultaneous detrusor pressure measurement in 104 patients with bladder outlet obstruction due to benign prostatic hyperplasia. In 49 patients (47%) a positive cooling reflex was observed. This was defined as a rise in the detrusor pressure following cold saline instillation exceeding 15 cmH2O (range 15-130 cmH2O, mean 60.6 cmH2O; positive group). In the remainder of cases the pressure rise ranged from 0 to 12 cmH2O (mean 6.1 cmH2O; negative group). Bladder outlet obstruction may cause some alteration in the afferent neural function of the bladder, in particular of the C-afferent fibers.

Aged↗
PubMed1999

Prognostic value of pressure-flow study in surgical treatment of benign prostatic obstruction.

The prognostic value of pressure-flow study (P-FS) in the surgical treatment of bladder outlet obstruction (BOO) was retrospectively studied in patients with benign prostatic hyperplasia. In 74 patients who underwent surgical treatment for BOO, P-FS and free uroflowmetry were performed pre- and postoperatively. On P-FS, obstruction and detrusor contractility were analyzed according to the Schäfer nomogram. The patients were classified into the following 3 groups according to their preoperative P-FS: group A consisted of 39 patients with normal detrusors and obstruction (obstruction grade 3-6); group B consisted of 13 patients with weak detrusors and obstruction; and group C included 22 patients with weak or very weak detrusors combined with minimal obstruction, if any (obstruction grade 0-2). Postoperatively, the detrusor pressure at maximal flow rate and obstruction grades on P-FS improved significantly in groups A and B but not in group C. The rate of improvement was most prominent in group A, followed by groups B and C. On free uroflowmetry, however, a significant improvement occurred in all three groups with respect to maximal flow rate, average flow rate, and postvoid residue. Moreover, the rate did not differ among the three groups except for the maximal flow rate as determined between groups A and C. Although good detrusor contractility and evident obstruction on analysis of P-FS will guarantee the best surgical outcome, subjects with weak detrusors and minimal obstruction will also have a good outcome by the relief of BOO. In the weak detrusor, P-FS may be limited in diagnosing obstruction and have a low prognostic value, and such patients should not necessarily be excluded from surgical indications.

Aged↗
PubMed1999

Measurement of hepatocyte growth factor in serum and plasma.

To investigate whether serum or plasma should be used for the measurement of blood hepatocyte growth factor, the levels were compared in 28 normal subjects and 30 patients who had undergone surgery. The serum level was significantly higher than the plasma level. The serum and plasma hepatocyte growth factor levels differed markedly depending on the subjects, although overall there was a significant correlation between levels (r=0.862, P=0.0001). In serum obtained by the clotting of platelet- or leukocyte-containing plasma with thrombin, hepatocyte growth factor increased in proportion to the number of leukocytes. The difference between serum and plasma hepatocyte growth factor levels also correlated with the number of leukocytes in the patients (r=0.642, P=0.0004). Such a correlation was not observed for platelets. These findings suggest that the serum hepatocyte growth factor level does not strictly reflect the in vivo blood level, due to the release from leukocytes during sample preparation (i.e., blood clotting ) and that plasma is more suitable for assay of blood hepatocyte growth factor.

Blood Cell Count↗
PubMed1999

Evaluation of preoperative and intraoperative arterial stimulation and venous sampling for diagnosis and surgical resection of insulinoma.

BACKGROUND: The precise intraoperative localization of insulinoma is essential for successful surgical treatment. In addition to various imaging modalities developed recently, arterial stimulation and venous sampling (ASVS) has also been used for tumor localization. METHODS: Preoperative and intraoperative ASVS procedures were performed in 6 patients with insulinoma. Intraoperative ASVS was performed before and after tumor resection. Immunoreactive insulin (IRI) concentrations and the IRI ratio (IRI concentration at each time interval after calcium injection/baseline IRI concentration) were determined by the conventional or a quick IRI method. RESULTS: The site of the tumor was identified preoperatively in all patients. The peak of the IRI ratio varied widely, but setting the cutoff value at 3.0 clearly differentiated peak IRA ratios in feeding arteries from those of nonfeeding arteries. Intraoperative ASVS showed a similar elevation of IRI levels, but the elevation disappeared after tumor resection in all but 1 patient. In 2 patients, resection of the tumor was confirmed during surgery by measuring IRI levels by the quick IRI method. CONCLUSIONS: A combination of ASVS and conventional imaging modalities is useful for precise localization of insulinoma. Resection of the tumor can be confirmed intraoperatively by comparing IRI levels associated with preoperative and postresective ASVS.

Adult↗
PubMed1999

Evaluation of regional liver function by gadolinium-EOB-DTPA-enhanced MR imaging.

We evaluated the role of magnetic resonance (MR) imaging with gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA), in estimating regional liver function in a rat ischemia-reperfusion model. Ischemic liver damage was induced in the right lobe by vascular clamping for 0 (sham), 30 (I-30), 60 (I-60), and 90 min (I-90 group). The ischemic lobes in the I-60 and I-90 groups was clearly visualized as a high intensity area in the T1 images at late phase of Gd-EOB-DTPA enhancement, Moreover, the T1/2 of signal intensity in ischemic lobes significantly correlated with the duration of vascular clamping. We also observed significant correlation between T1/2 and ATP concentration in the liver tissue (r = -0.719, P = 0.04). Our results indicate that MR imaging with Gd-EOB-DTPA is useful for evaluation of regional liver function in rats.

Animals↗
PubMed1999

Imaging of hydroperoxides in a rat glomerulus stimulated by puromycin aminonucleoside.

BACKGROUND: To determine the locus of the increased oxidation induced by puromycin aminonucleoside (PAN), we imaged hydroperoxides in glomeruli stimulated by PAN in vivo and in vitro. METHODS: Dichlorofluorescein diacetate (DCFH-DA) in cells makes dichlorofluorescein, a substance that fluoresces when reacted with hydroperoxides. Fluorescence was detected using a photon detection video camera connected to a microscope. Two kinds of isolated glomeruli of Wistar rats were examined. One was the glomerulus obtained from rats on the seventh day following the injection of PAN. In this case, glomeruli were incubated in a buffer containing 5 mM DCFH-DA. Another was the glomerulus collected at 30 minutes after a large amount of DCFH-DA was intravenously injected. These glomeruli were incubated with either PAN or phorbol myristate acetate (PMA) in Krebs-Henseleite bicarbonate buffer. RESULTS: The images from the glomeruli treated by PAN in vivo resemble pictures of a galaxy by telescope. When the glomeruli were treated by PAN in vitro, two localized points appeared in each glomerulus after 15 minutes of incubation with PAN, and after 75 minutes of incubation, the fluorescence spread throughout the glomerulus. When glomeruli were incubated with PMA, two points that gave a very strong fluorescence were observed in each glomerulus, but they did not spread throughout the glomeruli. In both experiments, glomeruli without stimulants did not fluoresce. CONCLUSION: Increases in hydroperoxides were observed in the glomeruli from rats made nephrotic by exposure to PAN, and were also observed in glomeruli following 15 minutes of incubation with PAN in vitro.

Animals↗
PubMed1999

Prothiofos metabolites in human poisoning.

CASE REPORT: A 63-year-old woman was admitted to a local hospital after the ingestion of 40% prothiofos preparation (Tokuthion) 370 mL. Gastric lavage was performed and cathartics, active charcoal, diuretics, atropine sulfate, and pralidoxime were administered. Serum cholinesterase activity was 1.3 IU/L (normal 200-460 IU/L). The patient's consciousness was gradually restored after 4 hours of charcoal hemoperfusion and she was discharged 5 days after admission with no sequelae. METHOD: Plasma and urine prothiofos and metabolites were detected by gas chromatography-flame photometry and gas chromatography-mass spectrometry. Two despropyl metabolites were synthesized for identification and estimation. RESULTS: The main metabolites were identified with authentic prothiofos and methyl esters of synthesized des-S-propyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phosphate), despropyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phospholothiolate), and des-S-propyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorothioate). Despropyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorodithioate) was also identified in plasma. Large amounts of the hydrolyzed product, 2,4-dichlorophenol and its conjugate were also found. The metabolic pattern of prothiofos in humans appears to be different from that in rats.

Charcoal↗
PubMed1999

Radiofrequency catheter ablation for sinoatrial node reentrant tachycardia: electrophysiologic features of ablation sites.

The aim of this study was to investigate catheter ablation of sino-atrial reentrant tachycardia (SART) and the electrophysiologic characteristics of the ablation sites. From January 1990 to October 1997, 651 patients with supraventricular tachycardia were referred and 11 patients were found to have SART. Ablation was successful in all cases with a mean number of 3.3 radiofrequency (RF) current pulses. SART terminated during 22 of 36 RF pulses. In spite of prompt termination, tachycardia could be re-induced in 3 of 11 patients with its earliest activation site shifted. At effective ablation sites, the electrograms during tachycardia were characterized as fractionated (75+/-17 ms), and 38+/-16 ms prior to surface P wave, and 42+/-18 ms prior to the high right atrium. Unipolar electrograms revealed a sharp negative unipolar deflection, so called QS pattern, in 15 of 20 sites during SART and 15 of 15 sites during sinus rhythm. During effective applications, atrial premature beats (APB) with activation sequences identical to sinus rhythm appeared in 14 of 22 cases. Effective ablation sites of SART showed fractionated electrograms during tachycardia and sinus rhythm. Unipolar electrogram with a QS pattern and APB during energy application could be an indicator of the optimal ablation sites.

Adenosine Triphosphate↗