Biomedical subjects

T Kawata

Publications and source records attributed to T Kawata.

At least 19 recordsLinked to original sources

PubMed1995

Secretion and processing mechanisms of procathepsin L in bone resorption.

Secretion of procathepsin L into the culture medium from a bone cell mixture was markedly enhanced by addition of parathyroid hormone (PTH), 1 alpha,25-(OH)2D3 or tumor necrosis factor alpha (TNF alpha). These stimulators of secretion of procathepsin L enhanced bone pit formation, which was inhibited by E-64, but not by CA-074, a specific inhibitor of cathepsin B. Procathepsin L may thus participate in the process of bone collagenolysis during bone resorption. Procathepsin L partially purified from rat long bones under cold conditions was rapidly converted to the mature form under acidic conditions at room temperature. This conversion was inhibited by E-64, suggesting that the procathepsin L secreted into lacunae is catalytically converted to the mature enzyme by cysteine proteinase(s).

Animals↗

PubMed1995

Extracellular calcium causes the release of calcium from intracellular stores in chick osteocytes.

We have recently demonstrated that a rise in the extracellular divalent cation concentration induces a rapid elevation of cytosolic calcium in chick osteocytes. Here, we demonstrate that cytosolic calcium elevation that occurs in osteocytes on exposure to elevated extracellular calcium is independent of membrane voltage and is insensitive to modulation by organic calcium channel modulators, namely, BAY K 8644, nicardipine, and nifedipine. However, the calcium elevation was sensitive to modulation by an intracellular calcium antagonist, TMB-8, suggesting that the cytosolic calcium elevation was due to mobilization of this cation from an intracellular store.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1995

Usefulness of interlocking detachable coil for embolization of the major aorto-pulmonary collateral artery: a case report.

A 5-yr-old male had undergone a right-modified Blalock-Taussig shunt operation at the age of 1 mo for stenotic patient ductus arteriosus and pulmonary atresia with ventricular septal defect. Before a corrective operation, the angiogram revealed one large major aorto-pulmonary collateral artery from the descending aorta to the right upper lung. Embolization of the major aorto-pulmonary collateral artery was successfully performed using interlocking detachable coils. This is the first reported case of embolization of the major aorto-pulmonary collateral artery using this device.

Angiography↗

PubMed1995

Left atrial plication combined with mitral valve surgery in patients with a giant left atrium.

The benefits of performing left atrial plication during mitral valve surgery for patients with a giant left atrium were evaluated by analyzing the short- and long-term surgical results and changes in the left atrial dimension (LAD) and respiratory function of 30 patients. Of the 30 patients, 2 (7%) died of multiple organ failure on postoperative days 26 and 117, but no other deaths occurred during the mean follow-up of 5.9 +/- 2.1 years. Valve thrombosis was observed in one patient and cerebral complications with no residual deficit were observed in two patients, with a 9-year event-free rate of 87 +/- 7%. The LAD decreased significantly from 69.0 +/- 8.5 mm to 53.7 +/- 9.1 mm (P < 0.01) shortly after surgery, and this decreased was maintained even 5 years after surgery (53.3 +/- 11.4 mm). The cardiothoracic ratio decreased from 74.8 +/- 8.3% to 62.8 +/- 9.0% (P < 0.01) and the vital capacity of the lungs increased from 71.1 +/- 18.0% to 82.9 +/- 22.2% (P < 0.01). Thus, we conclude that performing left atrial plication during mitral valve surgery is safe and effective for patients with giant left atrium.

Adult↗

PubMed1995

Systolic and diastolic function after patch reconstruction of left ventricular aneurysms.

Left ventricular function after patch reconstruction for postinfarction left ventricular aneurysms is largely unknown. In this study, 16 patients with an anteroseptal-lateral left ventricular aneurysm were treated by reconstruction of the left ventricle using a Dacron patch. Coronary artery bypass grafting was performed concomitantly in 9 patients. The size of the patch used was 57% +/- 19% of the resected myocardial scar area, including the sewing cuff area to be sutured. In these patients, the ejection fraction increased significantly from 0.28 +/- 0.12 to 0.39 +/- 0.12 (p = 0.007) at rest and from 0.32 +/- 0.14 to 0.41 +/- 0.10 (p = 0.008) during exercise. The left ventricular end-diastolic pressure and left ventricular end-diastolic volume index were reduced significantly from 14 +/- 7.0 to 8 +/- 3.2 mm Hg (p = 0.032), and from 178 +/- 116 to 92 +/- 21 mL/m2 (p = 0.016). The peak filling rate was improved significantly from 1.2 +/- 0.47 to 1.8 +/- 0.6/s (p = 0.048) postoperatively. The ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase, at the level of the mitral valve, improved (p = 0.016) after operation and remained improved up to 16 to 24 months after operation. Patch reconstruction of the left ventricle resulted in the recovery of systolic and diastolic function soon after operation, which has persisted into the late postoperative period.

Blood Pressure↗

PubMed1995

Subcutaneous tissue reaction to synthetic auditory ossicle (Apaceram) in rats.

A study was carried out in order to obtain further information about the soft tissue response to thin Apaceram discs of dense hydroxyapatite (HA) implanted in rats for various periods of time between one day and 10 months. The Apaceram discs were implanted subcutaneously into the interscapular region of 33 rats. A sham operation was performed on eight rats used as controls. Decalcified histological sections stained with haematoxylin and eosin and Mallory's azan were examined and the different cell types found around the implants were counted. It was found that an acute inflammatory reaction occurred after one day and disappeared at about two weeks after implantation. In the test groups, macrophages and lymphocytes disappeared about one week later, and no inflammatory reaction was observed from one to three months. However, a tissue reaction occurred at six months with the appearance of macrophages and lymphocytes, and decreased gradually at 10 months. Meanwhile, a few foreign body giant cells at the Apaceram-tissue interface and a thick layer of fibrous connective tissue around the Apaceram disc were observed at 10 months. No osteogenesis was observed in any specimen. The results obtained so far suggest that Apaceram is still a useful material for reconstructive surgery, despite the possible appearance of a slight macrophage reaction at six months.

Animals↗

PubMed1995

Remodeling mechanisms of transseptal fibers during and after tooth movement.

The remodeling mechanisms of transseptal fibers during and after tooth movement were investigated histologically. An autoradiographic study was conducted to assess the synthetic response. One hundred fifty male Wistar strain growing rats were divided into three groups--one control and two experimental groups. Animals in the experimental groups were subjected to tooth movement with 25 g and 150 g of force. Maxillary first and second molars were separated and retained mechanically. Transseptal fibers were stretched in proportion to the amount of force applied for up to 2 days. Dynamic remodeling with proliferation of fibroblasts during tooth movement and slow rearrangement during retention periods occurred in both experimental groups. Collagen phagocytosis within the fibroblasts was observed ultrastructurally during the experimental periods. The number of silver grains in fibroblasts in the collagen fibers increased 160% the first day and 206% during the first 3 days. Proliferating fibroblasts remodeled the transseptal fibers through the synthesization and degradation of collagen fibers.

Alveolar Process↗

PubMed1995

Size-reduced cryopreserved pulmonary valve allograft for an RV-PA conduit: technical modification and functional evaluation.

Cryopreserved pulmonary allografts harvested from adults at the time of kidney donation were size reduced and used in two children with pulmonary atresia and ventricular septal defect. A technical modification for the creation of size-reduced pulmonary allograft conduits is described. Postoperative ultrasonic and cineangiographic assessments revealed excellent function of the pulmonary bicuspid valved conduit with a minimal pressure gradient and essentially no regurgitation. Although the long-term fate of cryopreserved bicuspid pulmonary valve and conduit is unknown, this conduit provides excellent handling characteristics that render allograft conduits preferable to synthetic conduits. In addition, the remodeled bicuspid pulmonary allograft conduits have exhibited excellent hemodynamic characteristics and are a reasonable alternative to other types of conduits when an appropriate size allograft is not available.

Adult↗

PubMed1995

Agonistic and antagonistic activities of bacterially derived Rhodobacter sphaeroides lipid A: comparison with activities of synthetic material of the proposed structure and analogs.

Lipid A from the photosynthetic bacterium Rhodobacter sphaeroides (RSLA) has been previously shown to antagonize many of the effects of endotoxins from more pathogenic gram-negative bacteria. We have reported on the synthesis of the proposed structure of RSLA and determined that bacterially derived RSLA is not identical to its proposed structure (W.J. Christ, P. D. McGuinness, O. Asano, Y. Wang, M. A. Mullarkey, M. Perez, L. D. Hawkins, T. A. Blythe, G. R. Dubuc, and A. L. Robidoux, J. Am. Chem. Soc. 116:3637-3638, 1994). Here we report results of analyzing the antagonistic and agonistic activities of bacterially derived RSLA in comparison with the activities of chemically synthesized material of the proposed structure of RSLA and analogs. Results indicated that all compounds were approximately equally potent at inhibiting endotoxin-induced release of tumor necrosis factor alpha from human monocytes and human whole blood as well as endotoxin-induced generation of nitric oxide in murine macrophages. In addition, all compounds were of equivalent potencies at inhibiting the binding of 125I-labelled lipopolysaccharide derivatized with 2-(p-azido-salicylamido) ethyl-1-3'-dithiopropionate to murine macrophages. Higher concentrations of bacterially derived RSLA (10 to 100 microM) were agonistic in human and murine assays. In gamma interferon-treated murine macrophages, agonism was exhibited at concentrations as low as 100 nM. In contrast, all synthetic materials were either dramatically less agonistic or devoid of agonistic activity when tested at concentrations as high as 100 microM. It is possible either that bacterially derived RSLA contains a small amount of a highly agonistic impurity or that the agonistic activity of RSLA is intrinsic to its molecular structure. In either case, these biological results support our previous report concluding that biologically derived RSLA is not identical to synthetic material of its proposed structure.

Animals↗

PubMed1995

[Morphology of the mandibular condyle in osteopetrotic (op/op) mouse].

Osteopetrosis is an inherited metabolic disease which produces an excessive accumulation of bone caused by deficiency of osteoclasts. It is characterized by systemic bone sclerosis, cranial deformation and failure of tooth eruption due to defective bone resorption. In this study, morphological change of the mandible was observed in growing osteopetrotic (op/op) mutant mice. Deformation of the condylar process, non-ossification of the condyle head and underdevelopment of the lateral pterygoid muscle were observed in the mutant mice. Although these phenomena were brought about by failure of the bone remodeling, it was simultaneously suggested that the ossification of the condyle head concerned with the mastication.

Animals↗

PubMed1995

[Konno's operation for residual aortic stenosis following Nick's operation--a case report].

A 43-year-old woman successfully underwent the Konno's operation as a reoperative procedure for residual aortic stenosis following the Nicks' operation. The patient had had congenital valvular and subvalvular aortic stenosis and a patent ductus arteriosus previously divided. At age 33, she had undergone the Nicks' operation (posterior ring enlargement) and aortic valve replacement with a 19 mm Bicer valve prosthesis 9 years 6 months prior to the reoperation. The preoperative left ventricular-aortic pressure gradient was 120 mmHg which decreased but remained about 60 mmHg after the Nicks' procedure. The patient again developed heart failure and frequent episodes of atrial fibrillation which required repeated hospital admissions. Approximately 10 years following the original procedure, the Konno's operation (anterior ring enlargement) was performed using a 23 mm St. Judes Medical aortic prosthesis to manage residual aortic stenosis. The postoperative course was uneventful and the left ventricular-aortic pressure gradient reduced to 16 mmHg. We conclude that the Konno's operation can be safely performed for residual aortic stenosis following the Nicks' operation.

Adult↗

PubMed1995

[Rest and exercise performance of allografts, Bicer valves and St. Jude Medical valves in the aortic position].

Cardiac catheterization was performed to measure pressure gradients and hemodynamic parameters at rest and during supine bicycle exercise in 37 patients with aortic valve replacements, using allograft valves. Bicer prosthetic valves and SJM prosthetic valves of 19 to 27 mm diameter. Fourteen patients had an allograft valve replacement, 17 a Bicer valve, and 6 a St. Jude Medical valve. Patients were comparable for age, valve size, body surface area and left ventricular systolic function. There were no statistical differences among three groups for body surface area, left ventricular end-systolic and end-diastolic volume indices, exercise cardiac index, exercise heart rate, or workload achieved. In all 37 patients left ventricular and ascending aortic pressures were measured simultaneously according to the Brockenbrough method. In a 21 mm valve size, the mean pressure gradient was higher for Bicer and St. Jude Medical prosthetic valves than for allograft valves, both at rest (8.0 +/- 3.5 mmHg for Bicer, 5.0 +/- 1.4 mmHg for St. Jude Medical versus 0 +/- 0 mmHg for allograft; p < 0.05) and during exercise (11.0 +/- 4.9 mmHg, 10.0 +/- 2.8 mmHg versus 0 +/- 0 mmHg, respectively: p < 0.05). In a 23 mm size, there were no significant differences among three groups for resting mean pressure gradient, but during exercise the mean pressure gradient was higher for Bicer and St. Jude Medical prosthetic valves than for allograft valves (8.4 +/- 9.3 mmHg, 5.5 +/- 4.4 mmHg versus 0 +/- 0 mmHg; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

[Surgical repair of bilateral atrioventricular valves in corrected transposition of the great arteries].

The patient was a 50-year-old man who had an SLL-type corrected transposition of the great arteries (C-TGA) accompanied by significant regurgitation of the bilateral atrioventricular valves, atrial septal defect (ASD), persistent left superior vena cava, atrial fibrillation, and ventricular extrasystoles. The systemic tricuspid valve was repaired with a 28 mm Carpentier-Edwards ring (C-E ring) for the mitral valve, while the systemic mitral valve was repaired with a 32 mm C-E ring for the tricuspid valve. Simultaneously, the associated ASD was closed. Although mild tricuspid valve regurgitation persisted postoperatively, his general condition greatly improved. The report of valve repair for both atrioventricular valves in C-TGA is rare, and only 6 such cases have been reported in the Japanese literature.

Heart Valve Prosthesis↗

PubMed1995

Efficacy and limitation of a left ventricular assist system in a patient with dilated cardiomyopathy accompanying multi-organ dysfunction.

A left ventricular assist system (LVAS, Toyobo CO., LTD., Japan) was used to provide life support for 190 days in a 44-year-old male patient with end-stage dilated cardiomyopathy. Before LVAS implantation, heart failure and cardiogenic shock with multi-organ dysfunction progressed despite the use of intra-aortic balloon pumping (18 days), mechanical ventilatory support (15 days), continuous veno-venous hemofiltration (two days) and intravenous administration of catecholamines. Before LVAS implantation, the patient had marked hepatic and renal dysfunction (total bilirubin 6.1, BUN 73 and serum creatinine 3.1 mg/dl). Those functions returned to normal (total bilirubin 1.2, BUN 11 and serum creatinine 0.6 mg/dl) one month after implantation. He was complicated by multiple cerebral embolisms occurring on the 9th, 57th and 175th postoperative days and died 190 days after surgery. Autopsy showed thrombi attaching to the diaphragm of the blood pump and multiple embolisms in the kidney and the spleen. By scanning electron microscopic examination, initial thrombi with attached erythrocytes were seen on the diaphragm surface without intimal lining formation. In conclusion, LVAS support can be useful for patients with end-stage heart disease complicated by multi-organ dysfunction. However, the LVAS may cause thromboembolic complications over the prolonged use.

Adult↗

PubMed1995

Anti-endotoxin activity of a novel synthetic lipid A analog.

Lipid As from non-toxic bacteria such as Rhodobacter capsulatus and Rhodobacter sphaeroides have been shown to antagonize the immunostimulatory effects of lipid A and LPS from pathogenic bacteria. We have biologically characterized a series of synthetic LPS antagonists including the proposed structures of the lipid A and R. sphaeroides containing fatty acid side chains ester-linked to the disaccharide backbone, as well as an analog of R. capsulatus lipid A containing ether-linked alkyloxy side chains (E5531). In vitro assays utilizing LPS-stimulated human monocytes or whole blood demonstrated that low nanomolar concentrations of E5531 inhibited cellular activation as indicated by decreased release of the cytokines TNF-a, and interleukins-1, 6, and 8. E5531 also inhibited LPS-induced release of cytokines and nitric oxide from murine macrophages. Synthetic antagonists at up to 100 microM were devoid of agonistic activity in murine and human in vitro systems. In vivo, E5531 blocked induction of TNF-a by LPS and reduced LPS-induced lethality in mice. These in vitro and in vivo results indicate that E5531 may have clinical therapeutic utility as an antagonist of endotoxin-mediated morbidity and mortality.

Animals↗

PubMed1994

Effect of retinoic acid on contraction of collagen gel induced by fibroblasts.

Retinoic acid inhibited the contraction of collagen gel containing fibroblasts. Moreover, in its presence fibroblasts extensions were shorter, fewer collagen fibers were recognized, cell adhesiveness was inhibited concentration-dependently, and microfilaments appeared to be disrupted, resulting in morphological changes including loss of multipolar cell processes due to changes in cytoskeletal linkages.

Cell Adhesion↗

PubMed1994

Divalent cations elevate cytosolic calcium of chick osteocytes.

Though it is proposed that osteocytes have several functions in bone metabolism, only limited definite information including results of calcium regulation has been forthcoming. We demonstrate here for the first time that the concentration of divalent cations, such as calcium, nickel and cadmium, directly regulates the cytosolic calcium concentration in osteocytes.

Animals↗

PubMed1994

The mechanisms and regulation of procathepsin L secretion from osteoclasts in bone resorption.

The secretion mechanisms of cathepsin L from osteoclasts in the process of bone resorption were investigated. The increases in bone pit numbers formed take place by PTH addition in parallel with the increases of cathepsin L and/or L-like proteinase activities in the culture medium of bone cells, and these were suppressed by the addition of calcitonin. The Z-Phe-Arg-MCA hydrolysing activity increased in the medium through the effect of PTH is considered to be a kind of procathepsin L by Western blotting analysis, and was suppressed by calcitonin addition. Furthermore, monensin inhibited not only the PTH-induced pit formation, but also cysteine proteinase activity in osteoclasts. Therefore, the procathepsin L excreted might be transferred from endothelial reticulum via Golgi and/or via lysosomes.

Animals↗