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Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 667 records · Page 37Linked to original sources
PubMed1995

Surface microarchitectural design in biomedical applications: preparation of microporous polymer surfaces by an excimer laser ablation technique.

In this report we demonstrate a microprocessing method to prepare microporous polymer films by an excimer laser ablation technique, which may enable the fabrication of functional biomedical devices such as advanced artificial organs. The irradiation of a KrF excimer laser pulses (wave-length 248 nm; fluence 1 J/cm2 pulse) onto several polymer films was achieved by passing a laser pulse through an optical microscope, resulting in the formation of an etched pit on the irradiated surface due to ablative photodecomposition. The number of pulses and the micropositioning of the irradiation were precisely controlled by a computer-aided control unit. Minimal ablation was observed for polyethylene with very small absorption coefficient (alpha) at 248 nm. For polymers which absorbed the laser photons, the etch depth increased linearly with number of pulses. The etch depth per pulse decreased with an increase in alpha values. An excellent structural quality, with micron-order precision of an etched pit, was found for those polymers with larger alpha values, such as polyimide, segmented polyurethane, and polycarbonate.

Biocompatible Materials↗
PubMed1995

Involvement of thromboxane A2 in bronchial hyperresponsiveness of asthma. Kanazawa Asthma Research Group.

It has been considered that thromboxane A2 (TXA2) is involved in the development of bronchial hyperresponsiveness (BHR), a characteristic feature of asthma. To ensure the involvement of TXA2 in BHR of asthma, effects of a 1-week treatment with two orally active TXA2 antagonists, BAY u 3405 and S-1452, on BHR were examined in 10 and 13 patients with stable asthma, respectively, in two consecutive double-blinded, randomized, placebo-controlled, two-phase crossover studies. Provocative concentration of methacholine causing a 20% fall in FEV1 (PC20-FEV1) with BAY u 3405 (0.78 (GSEM, 1.50) mg/ml) was significantly greater than the value with placebo (0.65 (GSEM, 1.46) mg/ml) (ratio 1.23 times, 95% CI 1.01 to 1.46: P = 0.0401). PC20-FEV1 was also significantly increased with S-1452 (0.43 (GSEM, 1.39) mg/ml) compared with placebo (0.29 (GSEM, 1.27) mg/ml) (ratio 1.75 times, 95% CI 1.05 to 2.45: P = 0.0189). Baseline pulmonary function was not altered by these treatments. These results may ensure that TXA2 is significantly involved in the BHR of asthma while the degree of contribution may be small.

Adolescent↗
PubMed1995

Variant type of teratoma appearing as a primary solid dermoid tumor in the rectum: report of a case.

We report herein the rare case of a 39-year-old woman found to have a primary solid dermoid tumor in the rectum. The patient presented after noticing a small amount of anal bleeding, and physical examination revealed a walnut-sized hard tumor, palpable in the anterior rectum, located about 9 cm from the anal verge. Morphologic examinations revealed a polypoid lesion with some hair surrounded by rectal mucosa, and four biopsy specimens from the lesion showed normal squamous epithelium. The tumor, which measured 2.5 x 2.1 x 1.3 cm, was removed by endoscopic polypectomy. Microscopically, the tumor was diagnosed as a solid dermoid tumor without a cyst, a variant type of mature teratoma or dermoid cyst. Since 1914, only 12 such cases, including ours, have been reported in Japan. The clinical features and diagnostic and therapeutic methods applied thereto are discussed.

Adult↗
PubMed1995

Surgical technique of laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis.

We report herein a new method of performing laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis, using refined surgical techniques. The pyloric tumor was immobilized by grasping the first portion of the duodenum and the anterior wall of the stomach, and electrocoagulation was used prior to incising the pyloric tumor to minimize bleeding during the procedure. Although this technique has been applied in only two patients so far, we present the details herein. We believe that with technical and instrumental refinements, the speed and safety of laparoscopic pyloromyotomy will improve and it will become an alternative to open surgery in pediatric patients.

Female↗
PubMed1995

Long-term results of intertrochanteric varus osteotomy for arthrosis of the dysplastic hip (over 10 years' follow-up).

We performed a retrospective clinical and radiographic review of the long-term results of 64 hips in 53 patients who underwent intertrochanteric varus osteotomy for arthrosis of the hip at the pre- or early stage with acetabular dysplasia. Their average age at operation was 26 years. The average duration of follow-up was 18 years and 10 months. The mean Harris hip score was 77 +/- 9 points pre-operatively, and improved significantly to 84 +/- 13 points at the final follow-up. The acetabular coverage influenced the final outcome, and the postoperative prognosis was predictable from the acetabular head index (AHI) on a pre-operatively done hip maximum abduction radiograph (abd XP). We conclude that varus osteotomy for a dysplastic hip should be considered when the acetabular coverage is sufficient, and that a good prognosis can be expected when AHI on abd XP is greater than 60%.

Adolescent↗
PubMed1995

Experimental assessment of newly devised transcatheter stent-graft for aortic dissection.

Despite recent advances, surgical results for Stanford type B dissection are not yet satisfactory because the procedure is so highly invasive. The aim of this study was to devise a new intraaortic (IA) graft that would offer less invasive treatment for type B dissection. To close the entry of type B dissections using transcatheter placement, we devised an IA graft (inner diameter, 15-20 mm; length, 40 to 60 mm) in which a self-expandable stent was covered with a thin, open-cell-structured polyurethane jacket. In acute animal experiments in which type B aortic dissections were prepared in 4 mongrel dogs, IA grafts were implanted to close the entry using a transfemoral catheter sheath, and closure of all the entries was confirmed by aortography. In chronic experiments, five IA grafts for normal descending aortas and one IA graft for an experimentally dissected aorta were implanted to observe histologic biocompatibility for up to 8 months. Histopathologic examination conducted at the projected sacrifice periods revealed that endothelialization of the luminal surface of the IA graft had begun as early as 1 month after implantation and was completed within 4 months. The prototype device that we developed may be promising as an effective, minimally invasive therapeutic intervention for closure of the entry site of type B dissection.

Aortic Dissection↗
PubMed1995

Role of thromboxane A2 and platelet-activating factor in allergic bronchoconstriction in guinea pig airway in vivo.

Membrane-derived lipid mediators have been considered to play a major role in pathogenesis of bronchial asthma. However, the importance of and the interactions among each mediator are still unclear. We examined the role of thromboxane A2 (TXA2) and platelet-activating factor (PAF) in immediate asthmatic response (IAR) and interactions between these lipid mediators in guinea pig airway in vivo using a specific TXA2 antagonist S-1452 and a specific PAF antagonist Y-24180. We confirmed the activity of each antagonist, as S-1452 and Y-24180 significantly and dose-dependently inhibited bronchoconstriction induced by respective agonist inhalation. S-1452 inhibited IAR but Y-24180 did not, indicating that TXA2 plays a major role in IAR but PAF does not. S-1452 significantly inhibited PAF-induced bronchoconstriction but Y-24180 did not inhibit synthesized TXA2 (STA2)-induced bronchoconstriction, showing that the bronchoconstrictive effect of PAF is at least in part dependent on secondarily released TXA2, but TXA2 does not induce PAF production.

Administration, Inhalation↗
PubMed1995

Effect of a 5-lipoxygenase inhibitor, AL-3264, on propranolol-induced bronchoconstriction in guinea-pigs.

The administration of propranolol can provoke bronchoconstriction in asthmatic patients. We hypothesized that such bronchoconstriction may result from the inflammatory mediators released by an allergic reaction. We investigated the effect of AL-3264, a 5-lipoxygenase inhibitor, on propranolol-induced bronchoconstriction (PIB) after antigen inhalation in passively sensitized and artificially ventilated guinea-pigs. Our goal was to determine whether products of arachidonate 5-lipoxygenase are involved in such PIB. Bronchoconstriction occurred when 10 mg/ml of propranolol was inhaled 20 min after antigen challenge. Pretreatment with AL-3264 given in intravenous doses of 0.01 and 0.1 mg/kg 15 min after the antigen challenge significantly reduced PIB in a dose-dependent manner. Pretreatment with 0.1 mg/kg of AL-3264 10 min before antigen challenge significantly inhibited both the immediate allergic bronchoconstriction and PIB, although the effect was minimal. Results suggest that arachidonate 5-lipoxygenase products (such as leukotriene B4, C4, D4 or E4) are involved in the pathophysiology of PIB but their contribution may be small. Further studies using selective antagonists for each of these leukotrienes are needed to clarify their role.

Acrylamides↗
PubMed1995

Additive effect of continuous low-dose ofloxacin on erythromycin therapy for sinobronchial syndrome.

It has been established that long-term low-dose erythromycin therapy (EM therapy) is very effective for sinobronchial syndrome, a common condition in Japan characterized by chronic upper and lower airway inflammation. The effect does not result from its bacteriocidal activity and the detailed mechanisms are not known. It takes 3-6 months for EM therapy to improve the symptoms. This study was designed to evaluate the additive effect of continuous low dosage or intermittent usual dosage of ofloxacin (OFLX) on EM therapy in patients with sinobronchial syndrome. Patients with sinobronchial syndrome were randomly allocated to receive one of the following four regimens. Patients in Group A received both low-dose OFLX and EM therapy daily for 6 months. Patients in Group B received EM therapy and intermittent treatment of OFLX for 6 months. Patients in Group C underwent EM therapy for 6 months. Patients in Group D received neither OFLX nor EM therapy. All patients were given carbocystein for more than 2 months before starting each treatment and during the study period. In patients receiving OFLX and/or EM therapy, these antimicrobial agents were well-tolerated during the treatment period. Amount of sputum in the morning was significantly less in Group C than in Group D after 3-6 months, and decreased significantly in Group A as compared with Group B after 2 weeks, Group C after 2 weeks to 2 months, and Group D after 2 weeks to 6 months. Other symptoms such as number of expectorations, difficulty of expectoration and severity of cough also improved rapidly in Group A. These findings suggest that it is useful to add low-dose OFLX to EM therapy for sinobronchial syndrome, especially within 1-2 months from starting treatment, and it may be cost-effective as this combination therapy can shorten the treatment period of EM therapy.

Adult↗
PubMed1995

New phospholipase A2 inhibitor: synthesis and inhibition mechanism of oxazolidinone phospholipid analog.

(R)-3-Dodecanoyl-4-phosphatidylcholino-hydroxymethyl-2-oxazolidino ne (7), which is a new glycerophospholipid analog, was synthesized starting from (S)-glycidol through a 4-alkylsilyoxymethyl derivative and N-acyl-4-hydroxymethyl derivative. The cyclic amide analog 7 showed strong inhibitory activity toward both Group I and II PLA25, but the inhibitory potency of 7 was slightly weaker than that of the linear amide analog (R)-1, which had been developed by de Haas et al. (Biochem. Biophys. Acta 1990, 1043, 67). The interactions of 7 with human secretory PLA2 was investigated by computer modeling in comparison with those of the linear amide analog 1. The results of the computer modeling were very compatible with those of the inhibitory activities toward PLA2S, and the both results showed that the binding mode of the oxazolidinone analog 7 was very similar to that of the genuine substrate and was different from that of the linear amide analog 1.

Computer Simulation↗
PubMed1995

A hybrid vascular model biomimicking the hierarchic structure of arterial wall: neointimal stability and neoarterial regeneration process under arterial circulation.

A layered-structure hybrid vascular graft, mimicking the hierarchic structure of the intima and media of a natural artery, is expected to exhibit antithrombogenicity and to accelerate neoarterial tissue formation. Two models of hybrid vascular grafts were prepared on knitted Dacron fabric grafts (inner diameter 4 mm, length 6 cm). Model I grafts consisted of an endothelial cell monolayer formed on collagenous matrix, and model II grafts consisted of an endothelial cell monolayer that formed on hybrid collagenous medial tissue in which smooth muscle cells were incorporated. Both models (n = 17 for each model) were implanted bilaterally in carotid arteries and left in place for up to 26 weeks. Although all of the implanted grafts were patent, the two models significantly differed in the degree of maturity of the regenerated neoarterial wall especially at earlier implantation periods. At 2 weeks, model II grafts showed a much higher degree of neointimal integrity than model I grafts: a smooth and organized neointimal layer was formed, which was free from leukocyte adhesion. On further increase of implantation time, the formation of neomedia (subendothelial smooth muscle cell layers) and circumferential orientation of both smooth muscle cells and collagenous extracellular matrix were much more advanced in model II grafts than in model I grafts. At 26 weeks after implantation, layered elastic laminae regenerated along circumferentially oriented smooth muscle cells in neomedia were observed only in model II grafts. Irrespective of model, little excessive smooth muscle cell proliferation occurred. A hierarchically structured hybrid graft eventually provided a more integrated neointimal layer and accelerated neoarterial tissue formation much more than model I grafts. The significance of the incorporation of smooth muscle cells into hybrid grafts is discussed.

Animals↗
PubMed1995

Intracellular ascorbic acid inhibits the Na(+)-Ca2+ exchanger in cultured rat astrocytes.

The effect of ascorbic acid on Ca2+ uptake in cultured rat astrocytes was examined in the presence of ouabain and monensin, which are considered to drive the Na(+)-Ca2+ exchanger in the reverse mode. Ascorbic acid at 0.1-1 mM inhibited Na(+)-dependent Ca2+ uptake significantly but not Na(+)-dependent glutamate uptake in the cells, although the inhibition required pretreatment for more than 30 min. The effect of ascorbic acid on the Ca2+ uptake was blocked by simultaneous addition of ascorbate oxidase (10 U/ml). Na(+)-dependent Ca2+ uptake was also inhibited by isoascorbate at 1 mM but not by ascorbate 2-sulfate, dehydroascorbate, and sulfhydryl-reducing reagents such as glutathione and 2-mercaptoethanol. The inhibitory effect of ascorbic acid was observed even in the presence of an inhibitor of lipid peroxidation, o-phenanthroline, or a radical scavenger, mannitol, and the degrading enzymes such as catalase and superoxide dismutase. On the other hand, the inhibitory effect was not observed under the Na(+)-free conditions that inhibited the uptake of ascorbic acid in astrocytes. When astrocytes were cultured for 2 weeks in a medium containing ascorbic acid, the content of ascorbic acid in the cells was increased and conversely Na(+)-dependent Ca2+ uptake was decreased. These results suggest that an increase in intracellular ascorbic acid results in a decrease of Na(+)-Ca2+ exchange activity in cultured astrocytes and the mechanism is not related to lipid peroxidation.

Animals↗
PubMed1995

Nitroprusside and cyclic GMP stimulate Na(+)-Ca2+ exchange activity in neuronal preparations and cultured rat astrocytes.

The effects of nitric oxide (NO)-generating agents on 45Ca2+ uptake in rat brain slices and cultured rat astrocytes were studied in the presence of monensin, which is considered to drive the Na(+)-Ca2+ exchanger in the reverse mode. Sodium nitroprusside (SNP) at > 10 microM increased monensin-stimulated Ca2+ uptake in the slices, although it did not affect high K(-)-stimulated Ca2+ uptake. Another NO donor, 3-morpholinosydnonimine, was effective. The effect of SNP was antagonized by hemoglobin (50 microM), a NO scavenger, and mimicked by 8-bromo-cyclic GMP (100 microM). In rat brain synaptosomes, SNP increased monensin-stimulated Ca2+ uptake, but it did not affect high K(+)-stimulated Ca2+ uptake. 8-Bromocyclic GMP, but not SNP, increased Na(+)-dependent Ca2+ uptake significantly in synaptic membrane vesicles in the absence of monensin. In cultured rat astrocytes, SNP and 8-bromo-cyclic GMP increased Ca2+ uptake in the presence of ouabain and monensin, which were required for the Ca2+ uptake in the cells. These findings suggest that NO stimulates the Na(+)-Ca2+ exchanger in neuronal preparations and astrocytes in a cyclic GMP-dependent mechanism.

Animals↗
PubMed1995

Molecular analysis of mutations induced by 2-chloroacetaldehyde, the ultimate carcinogenic form of vinyl chloride, in human cells using shuttle vectors.

Vinyl chloride (VC) is a carcinogen associated with human and animal cancers. The ultimate carcinogenic form of VC, 2-chloroacetaldehyde (CAA), has been suspected to be mutagenic and we confirmed the mutagenicity of CAA using a modified shuttle vector plasmid. Base sequence analyses of 109 mutant plasmids with mutations in the supF gene, which were treated with CAA and propagated in the cultured human cells, revealed that more than half of the single base substitutions were G:C to A:T transitions with eight hotspots. The majority of the mutations involving G:C base pairs were in 5'-AAGG-3' or 5'-CCTT-3' sequences suggesting that these sequences are the main targets of mutagenesis caused by CAA.

Acetaldehyde↗
PubMed1995

Regional taste sensitivity to NaCl: relationship to subject age, tongue locus and area of stimulation.

Using a signal detection procedure and a microprocessor-controlled gustometer, sensitivity to three concentrations of NaCl (0.01, 0.1 and 1.0 M) was measured on the tongue tip, and on a region 3.0 cm posterior to the tongue tip in 12 young (20-29 years of age) and 12 elderly (70-79 years of age) subjects. Stimulus duration was 2 s; the sizes of the tongue areas stimulated were 12.5, 25 and 50 mm2. On average, the young subjects were more sensitive to NaCl on the tongue tip than on the more posterior stimulation site and exhibited, at both tongue loci, an increase in detection performance as stimulus concentration increased. The elderly subjects, on the other hand, performed at chance level at both tongue loci for all three stimulus sizes and concentrations tested. No sex differences were observed. In the young subjects, the mean R-index increased monotonically as a function of stimulus size for the two highest NaCl concentrations at both tongue loci. A hyperbolic function provided the best fit to these data at the tongue tip, and an exponential function at the more posterior tongue region, implying a different pattern of spatial summation at these two sites. Overall, this study demonstrates that marked age-related changes in regional taste sensitivity to NaCl are present in elderly persons.

Adult↗
PubMed1995

Binding mode of phospholipase A2 with a new type of phospholipid analog having an oxazolidinone ring.

Inhibition of phospholipases A2 (PLA2s) by a new type of monodispersed phospholipid analog, 3-dodecanoyl-4-phosphatidylcholinohydroxymethyl-2-oxazolidinone (oxazolidinone-PC), was investigated by the pH stat assay method using monodispersed 1,2-dihexanoyl-sn-glycero-3-phosphorylcholine (diC6PC) as the substrate. The PLA2s used were those from bovine pancreas and cobra (Naja naja atra) venom (Group I) and from Japanese mamushi (Agkistrodon halys blomhoffii) venom (Group II). This new-type substrate analog was shown to inhibit competitively both types of venom and bovine pancreatic enzymes by binding to the active site in a similar manner to the carboxamide-type analog 2-dodecanoyl-amino-1-hexanol-phosphocholine (amide-PC). The binding of a stereoisomer, (R)-amide-PC, to N. naja atra (Group I) and A. halys blomhoffii (Group II) PLA2s was facilitated by the binding of Ca2+ to the enzymes. On the other hand, the binding of (R)-oxazolidinone-PC to the N. naja atra (Group I) enzyme was found to be independent of Ca2+ binding, while its binding to the A. halys blomhoffii (Group II) enzyme was markedly facilitated by the binding of Ca2+ to the enzyme. The binding of (R)-amide-PC to N. naja atra PLA2 (Group I) was markedly influenced by the ionization state of the catalytic residue His 48, whereas the binding of (R)-oxazolidinone-PC was found to be practically independent of the ionization state of this residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗