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Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 775 records · Page 43Linked to original sources
PubMed1994

An integrated approach to the design and engineering of hybrid arterial prostheses.

PURPOSE: A newly devised hybrid small-caliber graft was developed. The graft consisted of three components: a microporous polyurethane graft (inside diameter 3 mm; length 5 cm) with compliance close to that of a natural artery; an artificial basement membrane composed of a complex gel of type I collagen and dermatan sulfate, which showed enhanced adhesion and growth of endothelial cells (ECs) and reduced adhesion of platelets in vitro; and an autogenous EC monolayer with high degrees of cell-substrate and cell-cell interactions, which was performed before implantation. METHODS: Twenty EC-seeded grafts were implanted bilaterally into carotid arteries of dogs without anticoagulant. The implantation period was up to 26 weeks. RESULTS: The overall patency rate for seeded grafts was 75%. The percentage of endothelial coverage of seeded grafts was 98% as implanted, 92% at 2 weeks, and 100% after 12 weeks. The mean intimal thickness of grafts was around 80 microns at 12 weeks. Little additional increase was observed at 26 weeks. CONCLUSIONS: It appears that the complete endothelialization as implanted, high cell-to-substrate adhesive strength that resists hydrodynamic shear stress, and biomechanical compatibility of the polyurethane graft functioned cooperatively to provide a vascular graft with high antithrombogenicity and minimal hyperplasia. The integrated approach of combining biomechanical and cellular engineering designs leading to an important functional smaller-caliber graft is discussed.

Animals↗
PubMed1994

Vitamin C reduces ischemia-reperfusion injury in a rat epigastric island skin flap model.

Free radicals have been implicated in the cause of ischemia-reperfusion injury. Various agents have been used in an attempt to reduce ischemia-reperfusion injury pharmacologically, including free radical scavengers. Vitamin C (ascorbic acid), a well-known free radical scavenger, has not, to the best of our knowledge, been evaluated in this respect. Previous work at our institution has shown that vitamin C decreases capillary permeability, thus significantly reducing fluid resuscitation requirements in postburn cases. Because this is due in part to the scavenging effect of vitamin C on free radicals, we investigated the role, if any, of vitamin C on ischemia-reperfusion injury in a rat epigastric island skin flap model. Twenty-four adult Sprague-Dawley rats were divided into control and vitamin C groups. Superficial epigastric island skin flaps measuring 6.0 x 3.5 cm were raised. Pedicles were isolated and occluded with microvascular clamps for 6 hours. The flaps were then sutured back to their beds over Steri-Drape barriers. Fifteen minutes before reperfusion, the control group flaps were perfused via femoral artery cannulation with normal saline (2.5 ml/kg). The vitamin C-treated group was perfused in a similar fashion with 2.5 ml/kg of a vitamin C/normal saline solution (27 mg/ml). The animals were observed for 7 days, and the percentage of flap survival was determined using a paper template technique. The vitamin C-treated group demonstrated a significantly higher percentage of flap survival than did the control group (25.8% mean vs. 7.5% mean, p < 0.025). In this animal model, vitamin C reduced or limited reperfusion injury after 6 hours of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Study of the balance between coagulation and fibrinolysis in disseminated intravascular coagulation using molecular markers.

Plasma levels of thrombin-antithrombin III complex (TAT), plasmin-alpha 2-plasmin inhibitor complex (PIC) and active plasminogen activator inhibitor (PAI) were assayed in 66 cases of disseminated intravascular coagulation (DIC). Significant elevation of both TAT and PIC was observed in all cases of DIC. Most elevated levels of TAT were seen in DIC with acute promyelocytic leukaemia (APL) and sepsis. The highest levels of PIC were seen in DIC with APL but were much lower in sepsis. A significant elevation in active PAI was observed in DIC due to acute leukaemia (apart from APL), chronic myeloid leukaemia and sepsis, but not in APL, non-Hodgkin lymphoma and cancer. Active PAI was higher in patients with multiple organ failure (MOF) than in those without MOF while PIC was lower in patients with this complication. Thus, the balance of coagulation and fibrinolysis varied according to the underlying cause of DIC; APL had more dominant activation of fibrinolysis, while sepsis had greater activation of coagulation. It is suggested that the inhibition of secondary fibrinolytic activation plays an important role in the progression of MOF by the disturbance of the microcirculation.

Antifibrinolytic Agents↗
PubMed1994

Aerosolized acetaldehyde, but not ethanol, induces histamine-mediated bronchoconstriction in guinea-pigs.

It was reported that ethanol-induced bronchoconstriction was associated with elevated serum levels of acetaldehyde and histamine in Japanese asthmatic patients, but there is no study to investigate the airway response to acetaldehyde. We performed this animal study to test the hypothesis that acetaldehyde has the bronchospastic action via histamine release. First, we investigated the airway response to ascending doses (31.3, 62.5, 125, and 250 mM) of inhaled ethanol or acetaldehyde in guinea-pigs. Secondly, guinea-pigs pretreated with intraperitoneal injection of saline or 20 mg/kg diphenhydramine inhaled acetaldehyde. Finally, guinea-pigs pretreated with intraperitoneal injection of saline or 0.5 mg/kg atropine sulfate inhaled acetaldehyde. Inhalation of acetaldehyde, but not ethanol, caused bronchoconstriction in a dose-dependent manner. The bronchoconstriction induced by inhaled acetaldehyde was completely prevented by pretreatment with diphenhydramine. Atropine had no preventing effect against the acetaldehyde-induced bronchoconstriction. In conclusion, acetaldehyde has the bronchospastic action via histamine release in guinea-pigs. It is suggested that histamine H1-antagonists may be available for preventing alcohol-induced asthma.

Acetaldehyde↗
PubMed1994

Induction of multinucleated giant cells from rheumatoid arthritis (RA) synovial adherent cells by anti-DR antibody.

To determine the effects of signalling through the DR molecule on synoviocytes from RA patients, the synovial adherent cells were incubated with anti-DR antibodies. After 24 h incubation, we found the formation of multinucleated giant cells in that culture. These multinucleated giant cells showed characteristics of monocyte-macrophage lineage cells and precursor of osteoclasts. Cyclohexamide inhibited the formation of multinucleated giant cells, but not the aggregation of synovial cells, suggesting that newly synthesized proteins are associated with the cell fusion. These results revealed a new mechanism in multinucleated giant cell formation.

Antibodies, Monoclonal↗
PubMed1994

Effects of aerosol administration of a thromboxane receptor antagonist (S-1452) on experimental asthma in guinea pigs.

The importance of thromboxane A2 (TXA2), one of the arachidonate metabolites, in the pathogenesis of bronchial asthma has been emphasized recently. Because aerosolized administration of antiasthmatic drugs is effective and safe, this study examined the effect of aerosolized TXA2 receptor antagonist (S-1452) on allergic bronchoconstriction in passively sensitized and mechanically ventilated guinea pigs. Under the cover of antihistamine, antigen-induced bronchoconstriction was markedly inhibited by pretreatment with aerosolized S-1452 inhalation in a dose-dependent manner. Although aerosolized S-1452 itself provoked weak bronchoconstriction for its partial agonist effect, bronchial responsiveness to inhaled histamine did not change 10 min after S-1452 inhalation. These results indicate that aerosolized S-1452 may be useful in treating bronchial asthma.

Aerosols↗
PubMed1994

The augmented rectal bladder for urinary diversion: experience with the original valved rectum and a valve-less modification.

Kock's augmented and valved rectum was created in 10 patients following total cystectomy. During an observation period of up to 46 months, 4 patients died (1 from a recurrence of cancer, 1 from multiple organ failure subsequent to diabetes mellitus, 1 from coronary insufficiency, and 1 from cerebral hemorrhage). Post-operative complications included valve failure in 1, hydronephrosis in 2, and mild nocturnal urinary incontinence in another. Hyperchloremic metabolic acidosis was particularly notable in the cases without an intussuceptive valve of the rectum. Their base excess ranged from -6.9 to -15.0 mM/l but the condition was satisfactorily controlled by oral administration of alkaline agents. Although the present method has a number of shortcomings, the absence of a stoma and elimination of the need for self-catheterization are outstanding benefits. For these reasons, we believe that it is an effective option for urinary diversion.

Aged↗
PubMed1994

Laparoscopic varicocelectomy: invasiveness and effectiveness compared with conventional open retroperitoneal high ligation.

The invasiveness of laparoscopic varicocelectomy and open retroperitoneal high ligation of the internal spermatic veins were compared and the surgical effects on fertility of these two procedures determined. 48 of 97 men diagnosed with varicocele testis underwent laparoscopic varicocelectomy, while the remaining 49 underwent open retroperitoneal high ligation of the internal spermatic vessels. Operating time, number of post-operative days to walking, length of hospital stay and analgesic use were measured as peri-operative indicators of invasiveness. In addition, seminal parameters were determined in order to evaluate the effects of these procedures on fertility. The operating time required for laparoscopic surgery was significantly longer than that for open surgery (96.6 vs 78.1 min., p = 0.0078). The patients in the laparoscopic surgery group began walking earlier post-operatively than did those who underwent open high ligation (0.97 vs 1.42 days, p = 0.00037). Length of hospital stay for the laparoscopic patients was shorter than for the open surgery group (7.05 vs 9.55 days, p = 0.00001). There were no statistical differences between the groups in terms of semen quality or improvement in the post-operative rate of pregnancy of partners. These findings indicate that laparoscopic varicocelectomy is associated with a shorter period of convalescence than open high ligation of the internal spermatic vessels.

Adolescent↗
PubMed1994

Endothelium-derived relaxing factor released by 5-HT: distinct from nitric oxide in basilar arteries of normotensive and hypertensive rats.

1. The role of the endothelium in cerebrovascular responses to 5-hydroxytryptamine (5-HT) was investigated in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) in vitro. 2. Cumulative addition of 5-HT caused concentration-dependent contractions in ring preparations of SHR basilar arteries; the contractile response was smaller in WKY basilar arteries. 3. Removal of the endothelium enhanced markedly the contractile responses to 5-HT in WKY arteries but had only a slight effect in SHR arteries. The responsiveness to 5-HT in WKY arteries after removal of endothelium was comparable to that in SHR arteries. 4. The endothelium-dependent relaxation induced by acetylcholine in WKY basilar arteries was almost abolished by treatment with 10 microM methylene blue or 10 microM NG-nitro-L-arginine (L-NOARG). However, the response to 5-HT was not affected by treatment with methylene blue, L-NOARG or indomethacin. 5. Application of 10-20 mM K+ or 3.2 mM tetraethylammonium (TEA) did not change significantly, or only increased slightly, the resting tension, but markedly enhanced the contractile response to 5-HT in WKY arteries with endothelium. In contrast, the submaximal response to 5-HT in SHR arteries with endothelium was significantly enhanced by 0.3 mM TEA. 6. In the presence of 1 mM TEA, the application of 10 microM L-NOARG further enhanced the responses of 5-HT in WKY arteries with endothelium. In SHR arteries with endothelium, 10 microM L-NOARG per se enhanced slightly but significantly the responses to 5-HT. 7. These results indicate that 5-HT-induced contraction in basilar arteries is substantially attenuated by an endothelium-dependent mechanism in WKY, but to a much lesser extent in SHR. The major relaxing factor released by 5-HT from endothelium in WKY is distinct from NO and may exert its effect by activating K+ channels.

Animals↗
PubMed1994

Potentiating effect of inhaled acetaldehyde on bronchial responsiveness to methacholine in asthmatic subjects.

BACKGROUND: It has recently been reported that acetaldehyde induces bronchoconstriction indirectly via histamine release. However, no study has been performed to assess whether acetaldehyde worsens bronchial responsiveness in asthmatic subjects so this hypothesis was tested. METHODS: Methacholine provocation was performed on three occasions: (1) after pretreatment with oral placebo and inhaled saline (P-S day), (2) after placebo and inhaled acetaldehyde (P-A day), and (3) after a potent histamine H1 receptor antagonist terfenadine and acetaldehyde (T-A day) in a double blind, randomised, crossover fashion. Nine asthmatic subjects inhaled 0.8 mg/ml acetaldehyde or saline for four minutes. After each inhalation a methacholine provocation test was performed. RESULTS: Methacholine concentrations producing a 20% fall in FEV1 (PC20-MCh) on the P-A day (0.48 mg/ml, 95% CI 0.21 to 1.08) and T-A day (0.41 mg/ml, 95% CI 0.22 to 0.77) were lower than those on the P-S day (0.85 mg/ml, 95% CI 0.47 to 1.54). There was no change in the PC20-MCh between the P-A and T-A days. A correlation was observed between the logarithmic values of PC20-MCh (log PC20-MCh) on the P-S day and the potentiating effect of acetaldehyde on the methacholine responsiveness [(log PC20-MCh on P-A day)-(log PC20-MCh on P-S day)] (rho = 0.82). CONCLUSIONS: Acetaldehyde induces bronchial hyperresponsiveness in patients with asthma by mechanisms other than histamine release.

Acetaldehyde↗
PubMed1994

Is 300 msec too long for cardiac MR imaging? Feasibility study demonstrating changes in left ventricular cross-sectional area with use of single-shot turboFLASH imaging.

PURPOSE: To assess the feasibility of demonstrating cardiac motion with 313.6-msec single-shot turbo-fast low-angle shot magnetic resonance imaging. MATERIALS AND METHODS: Effects of motion on single-shot images were evaluated with a phantom moving at known velocity. Single-shot images were obtained in eight healthy volunteers and four cardiac patients and compared with conventional cine images. RESULTS: The moving phantom was visualized at the location where zero phase-encoded data were sampled. When the velocity was within the physiologic range of left ventricular wall motion (< 11 cm/sec), the full width at half maximum of the object on a 64 x 64-matrix image with a 4.9-msec repetition time was comparable with that of a stationary phantom. The left ventricular cross-sectional area determined with single-shot imaging showed good correlation with results of conventional cine imaging (r = .96) in healthy volunteers. CONCLUSION: Single-shot imaging can be used for simple and quick assessment of cardiac function.

Feasibility Studies↗
PubMed1994

Laparoscopic ureterolysis for idiopathic retroperitoneal fibrosis.

Ureterolysis and subsequent intraperitonealization were performed laparoscopically in 2 patients with unilateral idiopathic retroperitoneal fibrosis. The operative procedure was easily accomplished, and the outcome was excellent in the patient who had a ureteral stricture of 2 cm in length, whereas the operation was technically more complicated with a prolonged operation time in the other patient who had a stricture more than 5 cm in length. The convalescence period after the operation was short in both cases. Laparoscopic ureterolysis is a less invasive alternative to conventional open surgery, particularly in patients with involvement of a unilateral ureter of short length.

Constriction, Pathologic↗
PubMed1994

Microsurgical epididymovasostomy for obstructive azoospermia: factors affecting postoperative fertility.

Azoospermia due to epididymal obstruction can be treated by microsurgical epididymovasostomy with high patency rates. Twenty-four azoospermic patients with epididymal obstruction due to a variety of causes underwent 26 microsurgical epididymovasostomies. The overall patency rate following surgery was 80.8% and impregnation was achieved by 10 patients (41.7%). Factors affecting the postoperative impregnation rate were etiology and duration of obstruction. Patients with an obstruction for < or = 15 years, caused by epididymitis or post-vasectomy epididymal blow-out, achieved a higher impregnation rate than the others (8 of 9 vs. 2 of 11, p = 0.0019). The motility of epididymal sperm or the presence of serum antisperm antibodies had no apparent effect on postoperative fertility. Microsurgical epididymovasostomy is particularly effective in patients with epididymitis or vasectomy patients with a short-term obstruction.

Adult↗
PubMed1994

Involvement of thromboxane A2 in propranolol-induced bronchoconstriction after allergic bronchoconstriction in guinea pigs.

Although it is well recognized that beta-blockers can induce bronchoconstriction only in patients with asthma, mechanisms of the bronchoconstriction are not well known. We hypothesize that bronchoconstriction induced by beta-blockers may result from inflammatory mediators released by allergic reactions. In this study, we developed a guinea pig model for propranolol-induced bronchoconstriction (PIB) after antigen inhalation and investigated the effect of specific thromboxane (TXA2) receptor antagonists, S-1452 and ONO NT-126, on PIB in passively sensitized and artificially ventilated guinea pigs to determine whether TXA2 is involved in PIB. Propranolol caused bronchoconstriction with 10 mg/ml of propranolol was inhaled 20 min after antigen challenge. On the other hand, propranolol did not produce bronchoconstriction after antigen provocation in nonsensitized guinea pigs or after saline provocation in sensitized animals. Pretreatment of the animals with S-1452 in doses of 0.01 and 0.1 mg/kg and ONO NT-126 in doses of 1.0 and 10 micrograms/kg injected intravenously 15 min after antigen challenge as well as before antigen challenge reduced PIB in a dose-dependent manner. Bronchoconstriction caused by methacholine did not induce PIB. These results suggest that TXA2 has an important role in the pathophysiology of the PIB that develops after the allergic bronchoconstriction.

Administration, Inhalation↗