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Biomedical subjects

S Kitamura

Publications and source records attributed to S Kitamura.

At least 235 records · Page 13Linked to original sources
PubMed1998

Cationic uncouplers of oxidative phosphorylation are inducers of mitochondrial permeability transition.

To determine whether cationic uncouplers of oxidative phosphorylation induce permeability transition in mitochondria, the effects of the divalent cationic sulfhydryl cross-linker copper-o-phenanthroline (Cu(OP)2) and the cyanine dye tri-S-C4(5) on rat liver mitochondria were examined. Like Ca2+, they accelerated mitochondrial respiration with succinate and induced mitochondrial swelling when inorganic phosphate (Pi) was present in the incubation medium. The acceleration of respiration and swelling were inhibited by the SH-reagent N-ethylmaleimide, and by the specific permeability transition inhibitor cyclosporin A (CsA). In addition, these cations, like Ca2+, induced release of ADP entrapped in the mitochondrial matrix space, and the morphological change of mitochondria induced by these cations was essentially the same as that induced by Ca2+. It is concluded that the uncoupling actions of Cu(OP)2 and tri-S-C4(5) are due to induction of permeability transition in the inner mitochondrial membrane.

Adenosine Diphosphate↗
PubMed1998

Stereoselective determination of R,S-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid and its taurine conjugates in dog urine by high-performance liquid chromatography.

Two high-performance liquid chromatographic methods for the stereoselective determination of R,S-2-[4-(3-methyl-2-thienyl)-phenyl]propionic acid (R,S-MTPPA), a new anti-inflammatory agent, and its taurine conjugates (R,S-MTPPA-TAU) in dog urine have been developed and validated. The urine samples were subjected to solid extraction or TLC preparation, then R,S-MTPPA and R,S-MTPPA-TAU were separated on Chiralcel OD and Chiral AGP columns, respectively, with ultraviolet absorbance detection at 272 nm. The dose-response relationships for enantiomers of R,S-MTPPA and R,S-MTPPA-TAU were linear in the concentration ranges of 0.5-50 (r>0.9993) and 5-200 microg/ml (r>0.9982), respectively. Recoveries of all tested enantiomers from dog urine were roughly 90% within the above concentration ranges. Intra- and inter-day reproducibilities were sufficient for metabolic studies. These methods were applied to stereoselective determination of the enantiomers in dog urine after administration of either S- or R-MTPPA.

Animals↗
PubMed1998

Central pressor effect of parathyroid hormone-related protein in conscious rats.

Although the parathyroid hormone-related protein gene is widely expressed in the central nervous system, the role of this protein in blood pressure is unknown. This article examines whether parathyroid hormone-related protein is involved in the central regulation of blood pressure. An intraventricularly injected solution of parathyroid hormone-related protein elicited a dose-dependent increase of mean arterial pressure accompanied by a decrease of heart rate in conscious Sprague-Dawley rats. An anti-parathyroid hormone-related protein monoclonal antibody, given in an intraventricularly injected solution, blocked the pressor effect of parathyroid hormone-related protein. Furthermore, this pressor effect of parathyroid hormone-related protein was also abolished after pretreatment by intravenous administration of either hexamethonium bromide or doxazosin mesylate. These results suggest that central parathyroid hormone-related protein is implicated in the regulation of blood pressure, and that this effect may be mediated through sympathetic activation.

Analysis of Variance↗
PubMed1998

cDNA cloning of bovine thrombospondin 1 and its expression in odontoblasts and predentin.

The extracellular matrix protein thrombospondin 1 (TSP1) was cloned from odontoblasts of bovine mandibular teeth which participate in dentinogenesis. The 5289 bp cDNA contains a complete open reading frame of 1170 amino acids. Bovine TSP1 has high homologies to its human and mouse counterparts. In immunohistochemical analyses of bovine anterior teeth with anti-TSP1 monoclonal antibody, TSP1 was only detectable at the position of predentin, located between dentin and unmineralized dental pulp. Northern blot analysis showed high levels of two sizes of TSP1 mRNAs in odontoblasts but not dental pulp and gingiva. Previously we found that osteotropic factors such as calcitriol and TGF-beta induce TSP1 at the transcriptional level in clonal rat dental pulp cells. These results suggest a role of TSP1 in dentinogenesis and/or maintenance of dentin and dental pulp.

Amino Acid Sequence↗
PubMed1998

Scintigraphic evaluation of transtrochanteric rotational osteotomy for osteonecrosis of the femoral head. Comparison between scintigraphy, radiography and outcome in 34 patients.

Scintigrams and radiographs of 36 femoral heads in 34 patients before and after Sugioka's transtrochanteric rotational osteotomy for osteonecrosis of the femoral head were investigated prospectively. Patients were followed for more than 3 years after the operation. The patterns of early scintigrams made within 3 months of the operation were classified into four categories. All 4 patients with a large cold area evidenced collapse within 1 year despite good recovery of the weight-bearing surfaces immediately after operation on conventional radiograms. Twenty-two hips with no cold area in the femoral head did not demonstrate collapse. Femoral head collapse after rotational osteotomy can be predicted by early postoperative bone scintigraphy.

Adolescent↗
PubMed1998

Ultrastructural evaluation following catheterization of the fallopian tube with a hysteroscopic catheter.

PURPOSE: Our purpose was to assess the morphology and ultrastructural changes in the tubal epithelium following catheterization of the fallopian tube. METHODS: Fallopian tubes were obtained from 20 women who had undergone hysterectomies. Catheterization was performed in 20 tubes using a catheter developed for hysteroscopic tubal embryo transfer. The catheter has a 3-French diameter, tapering to 2 French (0.66 mm) at the tip portion. The 20 contralateral tubes served as controls and were not catheterized. Ultrastructural changes were examined by scanning electron microscopy and transmission electron microscopy. RESULTS: Scanning electron microscopy showed no transformation or defects of the tubal epithelium surface in catheterized or control tubes. Transmission electron microscopy showed no significant differences in the percentage of abnormal desmosomes and the percentage of basement membrane in ciliated and nonciliated cells between catheterized and noncatheterized tubes. No transformation or defects were observed in catheterized or noncatheterized tubes. CONCLUSIONS: These findings suggest that catheterization of the tube using a hysteroscopic catheter caused no acute damage to the tubal epithelium.

Basement Membrane↗
PubMed1998

Long-term benefits of internal thoracic artery-coronary artery bypass in Japanese patients.

OBJECTIVES: This study sought to determine the effects of grafting the internal thoracic artery (ITA) to the left anterior descending coronary artery (LAD) on long-term (10-year) survival, the cardiac death-free rate, and on the cardiac event-free rate in Japanese patients. BACKGROUND: The use of ITA grafts has been reported to enhance postoperative survival and to decrease the occurrence of cardiac events in the Western literature. However, the survival benefits in Japanese patients, who may have different prognoses with coronary artery disease and a different fate of a saphenous vein graft, have not yet been determined. SUBJECTS AND METHODS: A total of 954 consecutive patients who underwent coronary artery bypass graft operations (CABG) during the last 12 years at the Nara Medical University were followed and evaluated. Of these, 713 patients underwent ITA-CABG to at least the LAD (ITA group), and 241 patients received a saphenous vein graft (SVG) to the LAD (SVG group). At the time of operation, no significant difference was found between these two groups in age, sex ratio left ventricular ejection fraction, left ventricular end-diastolic pressure, cardiac index, incidence of unstable angina, or in the necessity for an emergency operation. However, those patients who received ITA-CABG had significantly higher incidences of diabetes mellitus, hyperlipidemia, and left main coronary artery disease. RESULTS: The 10-year cumulative graft patency rate for the LAD was 23% higher in the ITA group (90.3%) compared to the SVG group (67.0%), (p < .0001). Despite increased preoperative risk factors, patients in the ITA group showed significant improvements in their 5- and 10-year cumulative survival rates as well as in their cardiac death-free and event-free rates. Furthermore, this study demonstrated that ITA grafts improved the prognoses of patients with diabetes mellitus or left ventricular dysfunction and lowered both the long-term postoperative cardiac-death rate and the cardiac-event rate. CONCLUSIONS: The use of ITA grafts was effective in improving both the postoperative survival and cardiac event-free rates, and should be recommended in patients with diabetes mellitus or left ventricular dysfunction. ITA grafting to the LAD should be a routine operation in almost all categories of such patients.

Aged↗
PubMed1998

Which type of diffuse emphysema is adequately contracted by the Nd:YAG laser. An ex-vivo experiment.

Diffusely emphysematous lungs are not always effectively contracted by laser therapy; however, which type of diffuse emphysema that responds to laser therapy remains unclear. We macroscopically and histopathologically examined human lung tissue, which was resected from patients with carcinoma, after irradiation with an Nd:YAG laser. Forty-six lung lobes were irradiated with a non-contact mode Nd:YAG laser at a power setting 15 watts. Macroscopically, twenty samples of normal lungs revealed moderate contraction, fourteen samples of predominantly centrilobular diffuse emphysema showed significant contraction, and eight samples of predominantly panlobular diffuse emphysema with a slight elastic network showed slight contraction. Histopathologically, the normal lungs showed amorphous change of the collagen and severely contracted elastic fibers (amorphous degeneration) at the pleura and some parenchymal coagulation; the predominantly centrilobular diffuse emphysema showed contraction of elastic fibers and collagen (coagulative degeneration) in the pleura and adequate contraction of the elastic fibers in the parenchyma and the predominantly panlobular diffuse emphysema showed only slight coagulation of the visceral pleura and very little coagulation of the parenchyma. On ex-vivo lung, panlobular emphysema was inadequately contracted by laser therapy, due to elastic recoil. Centrilobular emphysema responded to laser treatment, due to the severe contraction of the elastic fibers.

Elastic Tissue↗
PubMed1998

Chronic pulmonary thromboendarterectomy complicated by antithrombin III deficiency and antiphospholipid syndrome.

Pulmonary thromboendarterectomy was performed on two patients with chronic pulmonary thromboembolism showing thrombotic tendency. Patient 1 was a 25-year-old male with the disease complicated by congenital antithrombin III deficiency. Patient 2 was a 21-year-old male with the disease complicated by antiphospholipid syndrome. Both patients were admitted to the center upon showing dyspnea. Lung perfusion scintigraphy revealed multiple defects in the right and left lungs. Pulmonary arteriography showed occlusion and stenosis from lobar to segmental arteries. Cardiac catheterization showed marked pulmonary hypertension. Pulmonary angioscopy confirmed the presence of organized thrombi while an intravascular ultrasound revealed a thickening of the pulmonary arterial walls in both lungs. After the insertion of an inferior vena cava filter in each patient, surgery was performed. Following a median sternotomy, a cardiopulmonary bypass was utilized to induce deep hypothermia at a pharyngeal temperature of 16 degrees C, after which a thromboendarterectomy of the bilateral pulmonary arteries was performed under intermittent circulatory arrest. A large amount of organized thrombi was extracted from these arteries. After surgery, both patients showed good postoperative outcome with improved blood flow in both lungs, reduced pulmonary arterial pressure and increased cardiac output.

Adult↗
PubMed1998

[Surgical treatment for mitral regurgitation associated with secundum atrial septal defect].

We reviewed 25 patients who underwent a mitral valvuloplasty, from 1984 to 1996, for mitral regurgitation (MR) associated with atrial septal defect (ASD). Mean grade of MR was 2.3 +/- 0.7. The locations of mitral valve lesion were as follows; Postero-medial side of the anterior leaflet (AML) (11 patients: 44%), posteromedial side to center of the AML (7 patients: 28%), whole of the AML (5 patients: 20%), center of the AML (1 patient: 4%), posteromedial side of the posterior leaflet (PML) (1 patient: 4%). In summary, the mitral valve lesion was located in the AML in 96% patients and were seen in the postero-medial side of 96% patients. Mitral valve repair was performed as follows; chordae shortening only (3 patients: 12%), chordae shortening + Kay's annuloplasty (9 patients: 36%), Kay's anuloplasty (10 patients: 40%), using artificial chordae only (1 patient: 4%), using artificial chordae + Kay's annuloplasty (1 patient: 4%), using artificial chordae + ring annuloplasty (1 patient: 4%). In 24 patients, the grade of MR was less than 2/4 in the early postoperative period. In one patient, the grade of 3/4 MR was still remained. Reoperation were required in 2 patients, because of gradual increase of MR, 9 years and 10 years after the initial operation, respectively. In another patient, the grade 3/4 MR recurrently occurred at 6 months after the operation. He has been well maintained medically. In all 4 patients who had more than the grade 3/4 MR postoperatively, the annuloplasty was performed with Kay's method and the cause of MR was poor coaptation around the center of the AML. The mitral valve lesion associated with ASD seemed to be the dislocation of the AML which cause the discrepancy of the coaptation zone between both leaflets, without any prominent prolapse and chordae elongation. We put a particular emphasis on that the mitral valve repair should be performed with the recognition of the etiology of the mitral valve lesion. Especially, if the lesion extends around the center of the AML, sufficient coaptation area of both leaflets at the center of the AML should be obtained by anuloplasty.

Adult↗
PubMed1998

Two differing salmon GnRH precursor mRNAs are co-expressed in the brain of sockeye salmon.

The localization of two salmon-type gonadotropin-releasing hormone (sGnRH) precursors, pro-sGnRH-I (short type) and pro-sGnRH-II (long type), was investigated by using in situ hybridization techniques in the brain of the landlocked sockeye salmon, Oncorhynchus nerka. We used 30-mer oligonucleotide probes complementary to pro-sGnRH-I and pro-sGnRH-II cDNA. No significant differences were observed in the localization of sGnRH neurons expressing pro-sGnRH-I and pro-sGnRH-II mRNAs; both were expressed in the olfactory nerve, the olfactory bulbs, the regions between the olfactory bulb and telencephalon, the ventral telencephalon, the preoptic area, and the hypothalamus. Almost all sGnRH neurons examined co-expressed both precursors. The expression of two sGnRH precursors in the same neuron and the wide distribution of such neurons in the brain suggest that there are no functional differences between the two precursors.

Animals↗
PubMed1998

Ontogenic development of salmon GnRH and chicken GnRH-II systems in the brain of masu salmon (Oncorhynchus masou).

Ontogenic development of salmon gonadotropin-releasing hormone (GnRH) and chicken GnRH-II systems in masu salmon (Oncorhynchus masou) was examined. Salmon GnRH was first detected by radioimmunoassay in the embryo on day 36 after fertilization. Salmon GnRH-immunoreactive fibers were detected initially by immunocytochemistry in the vicinity of the olfactory placode of the embryo (day 36) and were distributed widely in the brain as well as in the pituitary gland of fish just after hatching (day 80). Salmon GnRH-immunoreactive neuronal somata were first detected about 6 months after fertilization in the rostroventral brain area, ranging from the olfactory nerve to the preoptic area. Salmon GnRH neuronal somata were detected earlier by in situ hybridization than by immunocytochemistry. Neuronal somata expressing salmon GnRH mRNA were first detected in the vicinity of the olfactory epithelium on day 40 and then were seen to be migrating from the olfactory epithelium, along the olfactory nerve, on day 60 and in the transitional area between olfactory nerve and olfactory bulb on day 80. In the brain, these neurons were first detected in the ventral olfactory bulb on day 80, and thereafter they were also detected in the caudal brain regions. The chicken GnRH-II system was detected later than the salmon GnRH system; chicken GnRH-II was first detected by radioimmunoassay on day 57, and chicken GnRH-II-immunoreactive fibers were first detected on day 67. Chicken GnRH-II-immunoreactive neuronal somata were not detected during the observation period. These results suggest that salmon GnRH neurons derive from the olfactory placode and then migrate into the brain and that salmon GnRH is synthesized before chicken GnRH-II.

Animals↗
PubMed1998

Gene transfer into the donor heart during cold preservation for heart transplantation.

BACKGROUND: Ex vivo gene transfer to heart grafts may hold promise as a means of changing alloreactivity or xenoreactivity after transplantation. However, it remains to be determined how effectively gene transfer can be accomplished within a short time in cold-stored grafts that are ready to be transplanted. METHODS: We performed an experimental study using a replication-defective adenovirus (Adex1CALacZ) encoding the Escherichia coli beta-galactosidase (beta-gal) gene to perform gene transfer to heart grafts awaiting transplantation. Thirty hearts of Wistar rats were removed and their coronary arteries were perfused with University of Wisconsin solution containing 1 x 10(9), 1 x 10(10), or 1 x 10(11) plaque-forming units of the recombinant adenovirus at 4 degrees C for 60 minutes. As a control, other hearts were perfused with University of Wisconsin solution with an adenoviral vector that did not contain the beta-gal gene (Adex1w1) for the same period. After perfusion, the grafts were implanted in the necks of syngeneic adult rats. The grafts were removed each week after transplantation and their expression of beta-gal was assessed by 5-bromo-4-chloro-3-indoyl-beta-D-galactoside staining. RESULTS: Successful gene transfer and expression of the beta-gal gene were demonstrated in adenovirus-perfused hearts. Gene transfer occurred preferentially in the cardiomyocytes over the endothelial cells and smooth muscle cells of the coronary vessels. In hearts perfused with 1 x 10(9) plaque-forming units of the adenovirus, gene expression persisted for 4 weeks after transfer, but it diminished gradually and was minimal by day 28. Histologic analyses revealed slight inflammatory reactions in the myocardium. In hearts perfused with 1 x 10(10) and 1 x 10(11) plaque-forming units of the adenovirus, beta-gal diminished 3 weeks after transplantation and a prominent infiltration of leukocytes was recognized in the myocardium. CONCLUSIONS: This study demonstrated that the cardiomyocytes of heart grafts express an exogenous gene product after adenovirus-mediated gene transfer under hypothermic preservation conditions. However, immune or inflammatory reactions to recombinant adenoviruses must be taken into account when a large number of adenoviruses are injected into the coronary arteries.

Adenoviridae↗
PubMed1998

Tracheal replacement with cryopreserved tracheal allograft: experiment in dogs.

BACKGROUND: It has been difficult to perform tracheal allotransplantation without immunosuppression. To determine whether cryopreserved trachea can be used in tracheal replacement, we evaluated the viability of cryopreserved tracheal allografts in a canine model of immunosuppressant-free transplantation. METHODS: Cryopreserved tracheal allografts, which had been frozen to -80 degrees C in a programmed freezer and then stored in liquid nitrogen (-196 degrees C) (group 1, n = 6), fresh tracheal autografts (group 2, n = 5), and fresh tracheal allografts (group 3, n = 4) were transplanted into the thoracic segment of the trachea using an omental flap without immunosuppressive agents. RESULTS: All dogs in groups 1 and 2 survived, but in group 3, all 4 died of airway obstruction between 1 month and 2 months after operation. Histologically, the cryopreserved allografts displayed normal epithelium and cartilage, but the fresh allografts showed chronic inflammatory changes, no epithelium, and no cartilage. CONCLUSIONS: Cryopreserved tracheal allografts maintain their structural integrity after transplantation. The cryopreservation process seems to reduce the allogenic response of the trachea in canine models. Therefore, we believe the cryopreserved tracheal allograft is an excellent choice for tracheal replacement.

Airway Obstruction↗
PubMed1998

Elephant trunk procedure for surgical treatment of aortic dissection.

BACKGROUND: In surgical intervention for aortic dissection, a highly radical operation can be performed by distal anastomosis with a true lumen resulting in thrombotic closure of the dissecting lumen. In this anastomosis, the elephant trunk procedure, in which a graft is inserted into the distal true lumen, prevents blood flow leakage into the dissecting lumen at the anastomosis site and also strengthens this area. METHODS: We performed this procedure in 15 patients (8 men and 7 women). Acute aortic dissection was observed in 9 patients and chronic dissection in 6. Stanford type A dissection was diagnosed in 10 patients and type B in 5. RESULTS: Graft replacement of the ascending aorta and total aortic arch was performed in 10 patients and descending aortic replacement in 5. A graft with a diameter of 16 to 24 mm was inserted into the true lumen of the descending aorta, and the false lumen was closed. Subsequently, distal anastomosis was performed on the true lumen. There were two hospital deaths. Postoperative digital subtraction angiography showed good results in living patients, and computed tomographic scanning showed thrombotic closure in the dissecting lumen of the descending aorta. CONCLUSIONS: The elephant trunk procedure is useful for closing the false lumen of the distal aorta.

Acute Disease↗
PubMed1998

Difference in acetylcholine-induced nitric oxide release of arterial and venous grafts in patients after coronary bypass operations.

OBJECTIVES: In vivo investigation of nitric oxide release in coronary bypass grafts has not been reported. We studied acetylcholine-induced nitric oxide release in vivo of coronary bypass grafts and vasomotor responses to acetylcholine of grafted coronary arteries in patients after coronary bypass grafting. METHODS: We examined 24 internal thoracic artery grafts and 16 saphenous vein grafts in 39 patients. The mean ages of the patients were 65 years for the arterial grafts and 68 years for the venous grafts. Nitric oxide was measured as the plasma nitrite level by the Griess reaction. Before and after intragraft acetylcholine infusion (5 microg), blood was sampled from the distal end of the graft, and angiograms were taken and analyzed by cine-densitometry. RESULTS: The plasma nitrite concentration after stimulation with acetylcholine compared with the control value was 134%+/-52% at 4 minutes (p=0.05) and 184%+/-107% at 6 minutes (p=0.01) in the arterial grafts; in the venous grafts these values were 101%+/-24% at 4 minutes (p=0.96) and 108%+/-36% at 6 minutes (p=0.69). Low-dose acetylcholine dilated the coronary arteries supplied by arterial grafts by 6.3%+/-16.6% whereas coronary arteries supplied by venous grafts were reduced by 9.8%+/-11.8% in diameter and the vasoactive responses were different (p=0.01). CONCLUSIONS: In vivo internal thoracic artery grafts had more endothelium-derived nitric oxide release in response to acetylcholine than did saphenous vein grafts after coronary bypass grafting.

Acetylcholine↗
PubMed1998

Epithelial regeneration and preservation of tracheal cartilage after tracheal replacement with cryopreserved allograft in the rat.

OBJECTIVE: We investigated the origin of the epithelium in transplanted cryopreserved tracheal allografts in rats and tried to clarify the mechanism by which immunogenicity is reduced in this procedure. METHODS: Tracheal transplantation was performed with PVG rats (allele at the RT1 locus: c) used as donors and ACI rats (allele at the RT1 locus: a) as recipients. After resection of a 5-ring segment of the cervical trachea of an ACI rat, the trachea was reconstructed with the cryopreserved tracheal segment of a PVG rat (n = 6). No immunosuppressive agents or steroids were given. Histologic changes were determined and immunohistochemical staining was performed to investigate major histocompatibility complex class I antigens of the transplanted tracheal segment. RESULTS: Two months after tracheal transplantation, 6 surviving ACI rats were killed. Histologically, the epithelium and tracheal cartilage of the transplanted cryopreserved segment displayed normal structure. Immunohistochemical staining showed that the major histocompatibility complex class I antigen of the ACI rat was expressed in the epithelium of the transplanted segment and that the class I antigen of the PVG rat was expressed in the cartilage of the transplanted segment. CONCLUSIONS: After transplantation of the cryopreserved trachea, the epithelium of the transplanted cryopreserved segment originated from the recipient epithelium whereas the cartilage retained the structure of the donor trachea. We hypothesize that transplantation of a cryopreserved trachea leads to the growth of the recipient's epithelium over the donor trachea, thereby reducing the antigenicity of the transplant.

Animals↗