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Biomedical subjects

M Kitamura

Publications and source records attributed to M Kitamura.

At least 163 records · Page 9Linked to original sources
PubMed1998

Effect of a balanced biventricular bypass system on left ventricular energies.

Left dominant biventricular failure is a common type of heart failure after cardiac surgery. We developed a biventricular bypass (BVB) system for treatment of postcardiotomy ventricular failure, and we previously reported that the clinical results of the BVB system were superior to those obtained with venoarterial bypass (VAB). The purpose of this study was to evaluate the effect of the BVB system on left ventricular (LV) performance in comparison to that of VAB by means of the LV pressure-volume relationship (PVR). Eight adult mongrel dogs (14-21 kg) underwent VAB with right atrial and aortic cannulation. Left atrial cannulation was added for BVB, and both atrial drainage tubes were joined with a Y-shaped connector. The bypass flow was maintained at half of the baseline cardiac output (0.7-1.0 L/min), and the hemodynamic parameters were monitored. A high fidelity microtip catheter and a conductance catheter were used to evaluate LV function. The slope of the LV end-systolic pressure-volume relation (Emax), the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the LV stroke work (SW), LV potential energy (PE), LV pressure-volume area (PVA), the slope of the SW end-diastolic volume relation (PRSW), and an index of the LV energizing charge (ratio of PE/PVA) were assessed during transient occlusion of the inferior vena cava. LV contractility (Emax) showed no significant change during each experiment. Standardized LV work (PRSW) was reduced by BVB in comparison to the baseline and in comparison to VAB. The rate of LV energy charge (PE/PVA) significantly increased only during BVB. These results suggested that the BVB system might be an effective circulatory support for reducing LV work and improving the LV energizing charge in patients with severe heart failure after cardiac operation.

Animals↗
PubMed1998

Mechanical circulatory support for severe heart failure after operation.

To evaluate the clinical results of circulatory support for severe heart failure after operation, we examined 62 patients (39 males and 23 females) who underwent circulatory support for postoperative heart failure from 1984 to 1996. Their ages ranged from 22 to 78 (mean 52) years. In 62 patients, 35 had valvular, 25 had ischemic, and 2 had congenital heart disease. Postoperation, 29 patients underwent venoarterial bypass (VAB), 20 had biventricular bypass (BVB), and 8 had left ventricular bypass (LVB). The remaining 5 patients received a pulsatile left ventricular assist device (LVAD). The weaning and discharge rates of the patients by type of support were 51.7% and 31.0% with VAB, 75.0% and 55.0% with BVB, 87.5% and 37.5% with LVB, and 60.0% and 40.0% with LVAD, respectively. The complete results of this series (64.5% weaning rate and 40.3% discharge rate) were acceptable.

Adult↗
PubMed1998

Minimally invasive cardiac surgery in the adult: surgical instruments, equipment, and techniques.

To clarify the special instruments and equipment used for minimally invasive cardiac surgery (MICS), we examined the initial experiences with MICS operations with ministernotomy or minithoracotomy at our institution. Fifty adult patients with congenital, valvular, and/or ischemic heart diseases underwent MICS operations, and all surgical procedures were completed without conversion to full sternotomy. The length of the skin incision was about 10 cm or less in all patients. Postoperative recovery was favorable, and the majority of the patients were discharged from the hospital around the end of the second postoperative week. In this series of patients, an oscillating bone saw, lifting type retractor, 2 blade spreader, cannula with a balloon, and right-angled aortic clamp among other items, were very useful for successfully performing various operations with MICS approaches and techniques. The associated results suggest that MICS with ministernotomy or minithoracotomy was feasible using special instruments and equipment and could be encouraged for adult patients with various cardiovascular diseases.

Adult↗
PubMed1998

Relationship between preoperative assessment of organ function and postoperative morbidity in patients with oesophageal cancer.

OBJECTIVE: To find out if strict assessment of organ function preoperatively predicted morbidity and mortality in patients being operated on for oesophageal carcinoma. DESIGN: Retrospective study. SETTING: Teaching hospital, Japan. SUBJECTS: 178 patients operated on for oesophageal cancer 1989-1993. INTERVENTIONS: Oesophagectomy and reconstruction (using either stomach or colon) in one stage by a right thoracoabdominal approach in 173, and transhiatal resection in 5 with either poor pulmonary reserve or early lesions. MAIN OUTCOME MEASURES: Correlation between preoperative assessment of organ function and postoperative development of complications. RESULT: 79 patients (44%) developed complications and 6 died (3%). Pulmonary dysfunction preoperatively was significantly associated with the development of all complications (p=0.001) and of postoperative pulmonary complications (p=0.04). No other preoperative assessment correlated significantly with the development of postoperative complications. CONCLUSION: Accurate preoperative assessment of pulmonary function is a valuable indicator of postoperative morbidity.

Aged↗
PubMed1998

Well differentiated adult-type fibrosarcoma arising from the occipital subcutaneous tissue in a 17-year-old man: case report with immunohistochemical study.

We report a case of a 17-year-old man with a spindle cell tumor in the occipital subcutaneous tissue. The enucleated tumor, measuring 2.5 x 2.0 x 1.0 cm, had a broad-bean shape and well circumscribed border and was localized to the subcutis without dermal involvement. Microscopically, the tumor was composed of uniform spindle cells showing interlacing bundle formation and a herringbone pattern. The neoplastic cells were separated by collagen fibers in parallel fashion, the amount of which varied with different areas in the tumor. Mitotic figures were eight mitoses per 50 high-power fields in number. The neoplastic cells were positive for vimentin, Factor-XIIIa, alpha-smooth muscle actin and CD34, but negative for desmin, calponin, high molecular weight caldesmon, smooth muscle myosin heavy chain, collagen type IV, laminin and S-100 protein. These immunohistochemical results indicated that the neoplastic cells showed differentiation toward fibroblasts/myofibroblasts/dendritic interstitial cells. Although more than 50% of the neoplastic cells were positive for CD34, the present tumor should be diagnosed as well differentiated fibrosarcoma, adult type, rather than extrapleural solitary fibrous tumor and fibrosarcomatous areas of dermatofibrosarcoma protuberans, on the basis of routine microscopic findings mentioned above.

Adolescent↗
PubMed1998

Cloning and expression of the gene encoding flavodoxin from Desulfovibrio vulgaris (Miyazaki F).

The gene encoding a flavodoxin of Desulfovibrio vulgaris (Miyazaki F) was cloned, and overexpressed in Escherichia coli. A 1.6-kbp DNA fragment, isolated from D. vulgaris (Miyazaki F) by double digestion with SalI and EcoRI, contained the flavodoxin gene and its regulatory region. An expression system for the flavodoxin gene under control of the T7 promoter was constructed in E. coli. The purified protein was soluble and exhibited a characteristic visible absorption spectrum. HPLC analysis of the recombinant flavodoxin revealed the presence of an identical FMN to that found in the native D. vulgaris flavodoxin, and its dissociation constant with FMN was determined to be 0.38 nM. In vitro H2 reduction analysis indicated that the recombinant flavodoxin is active, and its redox potential was determined to be E1 = -434 and E2 = -151 mV using methyl viologen and 2-hydroxy-1,4-naphthoquinone, respectively. Its redox behavior was also examined with the recombinant flavodoxin adsorbed onto a graphite electrode. The mutant, A16E, was also produced, which revealed the feature of a conserved Glu residue at the surface of the molecule.

Base Sequence↗
PubMed1998

Expression of selenoprotein-P messenger ribonucleic acid in the rat testis.

It has been suggested that a plasma protein, selenoprotein P, functions as an antioxidant and that its mRNA is expressed ubiquitously, including in the testis. To determine its physiological function, we have investigated the expression of selenoprotein-P mRNA in the rat testis. Northern blot analysis showed that selenoprotein P was exclusively expressed in the Leydig cell fraction. In situ hybridization experiments further supported this observation. Testes of rats administered ethylene dimethane sulfonate (EDS) were also examined by Northern blot analysis. Selective degeneration of Leydig cells by EDS treatment resulted in disappearance of selenoprotein-P mRNA from the testis. Furthermore, upon recovery, in association with regenerative differentiation of Leydig cells, reappearance of the selenoprotein-P mRNA was observed. These results indicated that selenoprotein-P mRNA was predominantly expressed in the interstitial Leydig cells.

Animals↗
PubMed1998

A prospective comparative trial of a gonadotropin-releasing hormone analogue with clomiphene citrate for the treatment of oligoasthenozoospermia.

BACKGROUND: We undertook a prospective trial to compare the efficacy and adverse effects of a gonadotropin releasing-hormone analogue (GnRHa) and clomiphene therapy for idiopathic normogonadotropic oligoasthenozoospermia (INOA). METHODS: Between January and December 1995, 44 newly-diagnosed INOA patients were randomly allocated to treatment with GnRHa or clomiphene citrate. Efficacy was assessed by measuring changes in semen parameters prior to and after 3 months of treatment. Twenty-three INOA patients underwent GnRHa therapy with 15 microg of diluted buserelin acetate given once a day intranasally, and 21 INOA patients were treated with 50 mg of clomiphene citrate daily by oral administration. RESULTS: The mean sperm density in the GnRHa group increased from 16.1 x 10(6)/mL to 26.9 x 10(6)/mL (P < 0.05), while the mean sperm density did not change significantly in the group treated with clomiphene. Similarly, the mean sperm motility increased from 35.9% to 43.9% in the GnRHa group (P < 0.05), but did not significantly change in the clomiphene group. No adverse effects were observed in either group. CONCLUSION: This GnRHa treatment protocol can be administered as an outpatient and is hoped to benefit INOA patients.

Administration, Intranasal↗
PubMed1998

Regulation of invasive potential of human prostate cancer cell lines by hepatocyte growth factor.

BACKGROUND: The growth and progression of prostate cancer depends on the stromal-epithelial interaction which is under paracrine control. Hepatocyte growth factor (HGF), produced by mesenchymal cells, is a multifunctional growth factor stimulating the movement and growth of epithelial cells including cancer cells. We therefore assessed the relationship between the invasive potential of prostate cancer and HGF in vitro. METHODS: Three human prostate cancer cell lines were used including PC-3 and DU145 (androgen-independent), and LNCaP (androgen-dependent). We studied the expression of the HGF receptor c-met proto-oncogene (c-met) by Western blot analysis, and also determined the effects of HGF on cell scattering, and the mechanisms of invasion and proliferation, by microscopic observation, the matrigel invasion chamber assay, and the MTT assay. RESULTS: c-met was detected in PC-3 and DU145 cells, but not in the LNCaP cells. There was increased cell motility in the scatter assay and an increased cell invasive potential in the matrigel invasion chamber assay by stimulation with HGF only with DU145 cells. CONCLUSION: HGF plays an important role in the invasion and metastasis of the DU145 cell line through a paracrine mechanism mediated by the c-metreceptor. In the PC-3 cell line, the lack of downstream signal transduction after the c-met receptor is suggested.

Biocompatible Materials↗
PubMed1998

Establishment and characterization of a human Epstein-Barr virus-associated gastric carcinoma in SCID mice.

A transplantable human Epstein-Barr virus-associated gastric carcinoma (EBVaGC), designated KT, was propagated in severe combined immunodeficiency (SCID) mice for 12 passages. Mucin and cytokeratin expression and the Alu sequence in tumor DNA confirmed that the KT tumor was derived from human epithelial tissue. The identity of clonal EBV in the original and KT tumors was demonstrated by terminal repeat analysis of EBV DNA. The pattern of latency gene expression of EBV was the same in both tumors. EBER1 was presented similarly in tumor cell nuclei by in situ hybridization. Reverse transcription-PCR analysis also demonstrated Q-promoter-driven EBNA1 expression but not BZLF1, EBNA2, or LMP1 expression. Thus, the transplantable human EBVaGC KT retains the original EBV with the same latency gene expression and can serve as a model for this unique type of gastric carcinoma.

Adenocarcinoma↗
PubMed1998

Wnt-1 induces growth, cytosolic beta-catenin, and Tcf/Lef transcriptional activation in Rat-1 fibroblasts.

Genetic evidence suggests that regulation of beta-catenin and regulation of Tcf/Lef family transcription factors are downstream events of the Wnt signal transduction pathway. However, a direct link between Wnt activity and Tcf/Lef transcriptional activation has yet to be established. In this study, we show that Wnt-1 induces a growth response in a cultured mammalian cell line, Rat-1 fibroblasts. Wnt-1 induces serum-independent cellular proliferation of Rat-1 fibroblasts and changes in morphology. Rat-1 cells stably expressing Wnt-1 (Rat-1/Wnt-1) show a constitutive up-regulation of cytosolic beta-catenin, while membrane-associated beta-catenin remains unaffected. Induction of cytosolic beta-catenin in Rat-1/Wnt-1 cells is correlated with activation of a Tcf-responsive transcriptional element. We thus provide evidence that Wnt-1 induces Tcf/Lef transcriptional activation in a mammalian system. Expression of a mutant beta-catenin (beta-CatS37A) in Rat-1 cells does not result in a proliferative response or a detectable change in the cytosolic beta-catenin protein level. However, beta-CatS37A expression in Rat-1 cells results in strong Tcf/Lef transcriptional activation, comparable to that seen in Wnt-1-expressing cells. These results suggest that Wnt-1 induction of cytosolic beta-catenin may have functions in addition to Tcf/Lef transcriptional activation.

Animals↗
PubMed1998

The requirement of intercellular adhesion molecule-1 for neutrophil respiratory burst in the pulmonary circulation of rats infused with endotoxin.

Recently, we demonstrated direct evidence of respiratory burst of the neutrophil in the pulmonary circulation of the endotoxin-infused rat (Am. J. Respir. Crit. Care Med. 1995;152:348-354). To determine the role of intercellular adhesion molecule-1 (ICAM-1) in this model, we neutralized ICAM-1 using antirat ICAM-1 monoclonal antibody (mAb) 1A29. We observed and measured the number of sticking leukocytes and the amount of hydrogen peroxide (H2O2) in the pulmonary circulation of the endotoxin-infused rat by means of a fluoro-imaging technique. The rats received 4.5 mg/kg/h of endotoxin for 2 h. Ten rats received 2 mg/kg of mAb 1A29 20 min before the intravenous infusion of endotoxin. Although the pretreatment with mAb 1A29 did not reduce the number of leukocytes sticking to the pulmonary capillaries, it almost completely inhibited the H2O2 production of leukocytes in the rat lung infused with endotoxin. We confirmed that the leukocytes that produced H2O2 were neutrophil by an electron microscopic cerium technique. We conclude that, although ICAM-1 is not necessary for neutrophil to stick to the capillary in the rat pulmonary circulation infused with endotoxin, ICAM-1 is required for neutrophil H2O2 production in this model.

Animals↗
PubMed1998

Platelet-activating factor mediates intercellular adhesion molecule-1-dependent radical production in the nonhypoxic ischemia rat lung.

It has been reported that reperfusion is the most important factor in ischemia-reperfusion (I/R) injury. However, causes of I/R injury in the lung are controversial, because oxygen is always supplied if ventilation continues. Therefore, we hypothesized that nonhypoxic ischemia without reperfusion is sufficient for lung injury. To test our hypothesis, we measured both hydrogen peroxide (H2O2) production in the pulmonary circulation, by digital imaging fluorescent dichlorofluorescein, and microvascular permeability (MVP), by the Evans blue extravasation technique in the nonhypoxic ischemia rat lung. We made a nonhypoxic ischemia rat lung by clamping the left pulmonary artery. Both H2O2 production and MVP increased in the nonhypoxic ischemia rat lung. We also determined the effect of oxygen removal by clamping the bronchus in advance of pulmonary artery occlusion, intercellular adhesion molecule-1 (ICAM-1) neutralization with monoclonal antibody 1A29, and platelet-activating factor (PAF) receptor antagonist CV6209 on H2O2 production and MVP. These treatments inhibited both H2O2 production and MVP increase. At high-power viewing of the fluorescent dichlorofluorescein image, H2O2 was detected in the leukocytes within pulmonary capillaries. These data indicate that the nonhypoxic ischemia without reperfusion alone causes radical production and increases MVP. Furthermore, PAF and ICAM-1 contribute to these reactions.

Animals↗
PubMed1998

[Direct effects of Chinese herbal medicine "hochuekkito" on sperm movement].

BACKGROUND AND PURPOSE: Chinese herbal medicine, "Hochuekkito" is widely used for male infertility in Japan. There have been many reports concerning its clinical usefulness but very few reports of in vitro experiments studying the mechanism of its effects. In addition to stimulating germ cells, we analyzed its direct effects on sperm using computer assisted semen analyzer (CASA). MATERIALS AND METHODS: Motile sperm were prepared using swim up technique from semen collected from ten healthy volunteers. Sperm movements (motility, velocity, linearity) were analyzed by CASA after adding either serum containing anti-sperm antibody (ASA) or normal serum with or without Hochuekkito. RESULTS: Two hours after adding serum with ASA, the decrease of sperm motility was significantly reduced from 25.1% (92.8%-->67.7%) to 12.5% (92.9%-->80.6%) by adding Hochuekkito. No significant difference in velocity and linearity was observed between two groups. By adding normal serum, any of three parameters differed significantly with or without Hochuekkito. CONCLUSION: Protective effects of Hochuekkito on sperm was suggested. Although normal sperm with ASA was used in this report, since the sperm of infertile patients are said to be more fragile, this results imply that direct protective effect is one of the mechanism of Hochuekkito for male infertility.

Adult↗
PubMed1998

[Is medical linac suitable for high-precision stereotactic irradiation?: investigations in geometrical accuracies of gantry and couch].

Linac-based radiosurgery has many advantages over the gamma knife, including low initial cost and no need of source replacement. On the other hand, most of the medical linacs currently in use were not originally designed to be applied for radiosurgery, and, therefore, careful quality assurance programs are required. In the gantry-head of a linac, a small CCD video camera is mounted in a position optically identical to that of the x-ray source. The video signal from the camera was digitalized to be evaluated for geometrical errors. A metal ball fixed to the stereotactic base frame via XYZ-sliding rods was used as a simulated target. Displacements of the target from the isocenter were measured during rotation of the gantry. Displacements in the gantry-rotation plane were satisfactorily small, while those perpendicular to it were maximal at gantry position angles of 0 degree and 180 degrees. This error night be caused by gravitational vending of the heavy gantry head. Although other major errors of the linac were within one millimeter, the center of coach rotation around the isocenter did not coincide with the center of gantry rotation, probably owing to gravitational vending. Special care should be taken when very small collimators are employed.

Quality Control↗
PubMed1998

[Surgical results and long-term outcome after mitral and/or tricuspid valve re-replacement].

Based on the STS/AATS guidelines of 1996, we compared the long-term results after mitral (Re-MVR) and/or tricuspid valve re-replacement (Re-TVR) in a total 324 patients (Re-MVT 299.Re-MVT+TVR 19, and Re-TVR 6 patients) with those after initial valve replacement in 763 patients (MVR 741, MVR+TVR 6 and TVR 16 patients). The actuarial survival (AS), reoperation-free (RF), thromboembolism-free (TF), and freedom from all valve-related events (EF) rates at the 15th postoperative year were 69.3%, 82.4% 86.6%, and 48.9% after Re-MVR and 87.2%, 92.2%, 83.9%, and 61.4% after initial MVR, respectively. The only significant difference between the two MVR groups occurred in the RF proportion. Similarly, the incidence of valve-related events after Re-MVR+TVR or Re-TVR was the same as that after the initial operation for the respective valve lesions. These long-term results suggest that valve re-replacement for mitral and/or tricuspid valve lesions should be encouraged to the same extent as the initial operation.

Adolescent↗
PubMed1998

[Necrosis of the hepatocellular carcinoma nodule can aggravate metastasis].

Since the stroma of hepatocellular carcinoma is composed of sinusoid-like structures, cancer cells are readily released from the primary tumor with possible injurious consequences. A 63-year-old woman with hepatocellular carcinoma underwent percutaneous ethanol injection therapy. During this treatment, tumor thrombus developed in the right hepatic vein. Partial hepatic resection was performed. Six months later, multiple nodules appeared in the lung fields. Partial necrosis may have allowed the release of cancer cells from the primary tumor. Perioperative therapy should have an effect on intrahepatic micrometastases, because removal of the main tumor can be done surgically.

Carcinoma, Hepatocellular↗