PubMed Health⌕ Search

Biomedical subjects

Yasuko Tomizawa

Publications and source records attributed to Yasuko Tomizawa.

At least 19 recordsLinked to original sources
PubMed2007

A novel synthetic tissue-adhesive hydrogel using a crosslinkable polymeric micelle.

We prepared a novel tissue-adhesive hydrogel by using a polymeric micelle consisting of an aldehyde-terminated poly(ethylene glycol)-poly(D,L-lactide) (PEG-PLA) block polymer. A Schiff base is chemically formed between the amino groups in a polyallylamine and the aldehyde groups on the surface of polymeric micelles. The hydrogel was formed in approximately 2 s when the polymeric micelle solution and polyallylamine solution are mixed in vitro. The hydrogel was rapidly formed in vivo, and it adhered to a tissue surface. Our novel tissue-adhesive hydrogel creates no risk of infectious contaminations, because it consists of only synthetic materials. Further, PEG and PLA are known to be biocompatible and noncytotoxic. The results obtained in the present study show that a hydrogel prepared by the formation of a Schiff base between aldehyde and amine groups will potentially address the need for novel tissue-adhesive materials.

Cross-Linking Reagents↗
PubMed2007

Local injection of a sustained-release antiandrogen formulation into a target prostatic site: an experimental study.

OBJECTIVE: To evaluate the efficacy of one intraprostatic injection with sustained-release chlormadinone acetate (CMA-SR) in rats. MATERIALS AND METHODS: CMA, a steroidal antiandrogen, was enclosed in microcapsules for sustained-release (CMA-SR). Forty-eight rats were divided into group A (intraprostatic CMA-SR 8 mg/kg, one injection), group B (as A but with 25 mg/kg), group C (intraprostatic, vehicle only) and group D (subcutaneous, s.c., CMA 10 mg/kg once daily for 4 weeks). Prostate weight, body weight and plasma testosterone levels were measured for up to 4 weeks. RESULTS: After a s.c. injection with CMA-SR, residual CMA at the s.c. injection site decreased with time. The injected prostate lobe weighed significantly (P < 0.05) less than the contralateral lobe in groups A and B, and significantly (P < 0.05) less in groups A and B than in group C. Both prostate lobes in group D were significantly (P < 0.05) smaller than in group C (P < 0.05). Plasma testosterone levels were significantly lower in group D than in group C (P < 0.05). CONCLUSIONS: The sustained release of CMA after one intraprostatic injection persistently decreased the weight of the target prostate. This new concept of antiandrogen therapy might therefore be effective in man, with fewer systemic adverse reactions.

Androgen Antagonists↗
PubMed2006

Corrosion of stainless steel sternal wire after long-term implantation.

A variety of metallic components have been used in medical devices where lifelong durability and physical strength are demanded. To investigate the in vivo changes of implanted metallic medical devices in humans, stainless steel sternal wires removed from patients were evaluated. Stainless steel (316L) sternal wires removed from four patients after 10, 13, 22, and 30 years of implantation were evaluated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Macroscopically, the removed specimens maintained their metallic luster and color. Under SEM, small holes were observed sporadically at 10 years and they tended to connect in the drawing direction. The longer the implanted duration, the more numerous and deeper were the crevices observed. By EDS, sulfur, phosphorus, and calcium were identified in all areas at 10 years, in addition to the component elements of stainless steel, comprising iron, chromium, nickel, and manganese. Corrosion products observed at 30 years were identified as calcium phosphate. In conclusion, stainless steel sternal wires develop corroded pores that grow larger and deeper with time after implantation; however, the pores remain shallow even after decades of implantation and they may not be a cause of mechanical failure. An amount of metal ions equivalent to the corroded volume must have been released into the human body, but the effect of these metal ions on the body is not apparent.

Bone Wires↗
PubMed2005

Survival benefit of exclusive use of in situ arterial conduits over combined use of arterial and vein grafts for multiple coronary artery bypass grafting.

BACKGROUND: The purpose of this study was to evaluate mortality after coronary artery bypass grafting (CABG) comparing the use of only in situ arterial grafts with the use of arterial and venous conduits. METHODS AND RESULTS: From April 1985 to March 1999, 1159 patients with multivessel disease underwent elective, isolated, primary, multiple CABG with at least one in situ arterial conduit. Patients who were on chronic dialysis, had active malignant disease, or had free arterial conduits were excluded. The long-term results were compared between 532 patients who had CABG using only in situ arterial conduits (group A; mean follow-up, 7.8 years) and 627 patients who underwent CABG using in situ arterial conduits and saphenous vein grafts (group B; mean follow-up, 10.3 years). Actuarial survival and freedom from cardiac death were determined by the Kaplan-Meier method. Propensity score was included in the Cox multivariable regression model for adjustment of selection bias. Survival at 10 years after surgery was 81.4% in group A and 76.9% in group B (P=0.11). Freedom from cardiac death at 10 years was 93.4% in group A and 90.4% in group B. Hazard ratio for cardiac death was significantly lower in group A (0.61; 95% confidence interval, 0.38 to 1.00; P=0.05). CONCLUSIONS: Our data suggest that the exclusive use of in situ arterial grafts in CABG achieves significantly better long-term survival compared with combined use of arterial and vein grafts.

Aged↗
PubMed2005

Clinical benefits and risk analysis of topical hemostats: a review.

A variety of local hemostats including absorbable gelatin sponge, collagen hemostat, and oxidized cellulose are commercially available. Local hemostats are applied when cautery, ligature, or other conventional hemostatic method is impractical. Proper handling is essential to control bleeding and only the required amount should be used, even though the hemostat is expected to dissolve promptly. A dry local hemostat absorbs body fluid of several times its own weight and expands postoperatively. Therefore, when an absorbable hemostatic agent is retained on or near bony or neural spaces, the minimum amount should be left after hemostasis is achieved. Documentation is important with regard to the hemostat used, including the name of the agent, site, and amount. This information is used as a reference in the interpretation of postoperative diagnostic images, since retained hemostat may sometimes mimic an abscess or recurrent tumor. The antigenicity of collagen is known to be low because of homology. When the safety of collagen was evaluated, the incidence of positive reactions was reported as 3.0%, and collagen may cause allergic reactions. Minimum inflammation without strong foreign body reactions or blockade of healing is desirable after the use of local hemostats. Strong foreign body reactions, chronic inflammation, and infections can cause granuloma formation after local hemostat use. By using local hemostats, it is possible to improve the condition of the patient, reduce complications, and lower direct and indirect costs.

Cellulose, Oxidized↗
PubMed2005

Left ventricular true aneurysm with pseudoaneurysm detected five years and nine months following repair for oozing type free wall rupture.

A case of true aneurysm of the left ventricle associated with pseudoaneurysm was treated surgically. The condition was detected five years and nine months following repair of an oozing type left ventricular free wall rupture due to myocardial infarction. Over this period, chest radiographs showed gradual cardiomegaly with prominence of the left fourth arch.

Adult↗
PubMed2005

Effects of colloid resuscitation on peripheral microcirculation, hemodynamics, and colloidal osmotic pressure during acute severe hemorrhage in rabbits.

We examined the effects of hydroxyethyl starch (HES) on the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of hemorrhagic shock. A total of 40 rabbits was anesthetized with pentobarbital and isoflurane, and they were mechanically ventilated. An ear chamber was prepared to examine blood vessels by intravital microscopy. Shock was induced by removing nearly half of the circulating blood volume. Twenty rabbits received 20 mL of HES by intravenous infusion immediately after blood letting. Additional HES was then administered intravenously to a total volume of 100 mL. The other 20 rabbits (control) were intravenously given 40 mL of lactated Ringer's solution (LR), followed by additional LR to a total volume of 200 mL, administered under the same conditions as HES. After blood letting, arteriolar diameter decreased similarly in the the HES and LR groups (HES, 40.5% +/- 14.8% of the baseline value versus LR, 43.3% +/- 13.1%). After the completion of infusion, arteriolar diameter significantly recovered to 90.8% +/- 10.2% of the baseline value in the HES group as compared with only 62.6% +/- 10.7% in the LR group (P < 0.005). Recovery of arterial blood flow velocity and blood flow rate was also significantly better in the HES group than in the LR group (P < 0.005). Mean arteriolar pressure, central venous pressure, and plasma colloid osmotic pressure after the completion of infusion were significantly greater in the HES group than in the LR group (P < 0.005). We conclude that intravenous infusion of HES effectively maintains the microcirculation, hemodynamics, and colloidal osmotic pressure in a rabbit model of acute severe hemorrhage.

Animals↗
PubMed2005

A single local application of recombinant human basic fibroblast growth factor accelerates initial angiogenesis during wound healing in rabbit ear chamber.

Local angiogenic therapy with recombinant human basic fibroblast growth factor (rhbFGF) has been used to promote wound healing. To obtain useful information for the development of optimal angiogenic therapy, we chronologically evaluated the effects of a single local application of rhbFGF on angiogenesis in a rabbit ear chamber model of wound healing by observing the subcutaneous vessel bed intravitally. New vessel formation during wound healing was macroscopically and microscopically evaluated for 5 wk. Each rabbit ear chamber received a single dose of 6 microg rhbFGF (treatment B1: n = 13), 18 microg rhbFGF (treatment B2: n = 16), or physiological saline as control (n = 13). At 1 wk the newly vascularized area was significantly larger in groups B1 and B2 than in control. At 2 wk, the vascularized areas in groups B1, B2, and control were similar. At 5 wk, the percentage of rabbits with complete vascularization was significantly larger in group B1 than in control. Capillary density at 5 wk was similar among the three groups. These results suggest that locally applied rhbFGF accelerated angiogenesis during early wound healing in rabbits; however, this effect was transient and no increase in capillary density occurred at the completion of vascularization.

Administration, Topical↗
PubMed2004

Deterioration of suture materials at prosthetic-host anastomoses.

We experienced a case of polypropylene suture rupture at anastomosis 5 years after fabric vascular graft implantation. Under a scanning electron microscope, the removed suture had a tapering-off breakage at the end and tortoiseshell-like deep cracks near the end. The tapered stump indicated that the suture had been stretched out gradually and had finally fractured.

Adult↗
PubMed2004

Transurethral ethanol injection therapy for prostatic hyperplasia: 3-year results.

PURPOSE: We assessed the medium-term (3-year) efficacy of transurethral ethanol injection therapy of the prostate (EIP) for benign prostatic hyperplasia. MATERIALS AND METHODS: A total of 34 patients were followed for a median of 4.3 years after EIP. Mean age was 68.1 years and mean baseline prostate volume was 49.3 ml. With the patient under combined sacral and urethral anesthesia, dehydrated ethanol was injected into the prostate with endoscopic guidance. A urethral catheter was inserted postoperatively. RESULTS: Mean total ethanol dose was 6.4 ml and a catheter was required for a mean of 7.6 days postoperatively. Mean International Prostate Symptom Score was 21.8 points before EIP (in 34 patients), and decreased to 13.1 points after 3 years (in 17, p <0.01). Mean quality of life index decreased from 5.0 points before EIP to 2.8 points after 3 years (p <0.001). Mean peak urine flow rate was 8.3 ml per second before EIP and increased to 12.7 ml per second after 3 years (p <0.01). Mean residual urine volume decreased from 93 ml before EIP to 28 ml after 3 years (p <0.01). Mean prostate volume decreased from 49.3 ml before EIP to 45.7 ml after 1 year (p <0.001), but increased to 51.4 ml after 3 years. No major complications were experienced. By 3 years after surgery 59.0% of patients had not required further treatment. CONCLUSIONS: Transurethral EIP caused minimal complications while maintaining improvement of the prostate symptom score and an increased peak urine flow after 3 years.

Aged↗
PubMed2003

Bilateral versus unilateral internal mammary revascularization in patients with diabetes.

BACKGROUND: This historical cohort study evaluated the benefit of bilateral internal mammary artery (BIMA) grafts in coronary bypass grafting (CABG) for patients with diabetes. METHODS AND RESULTS: We performed elective, isolated, primary, multiple CABG using skeletonized internal mammary artery (IMA) grafts for multivessel disease in 1131 patients, 467 (41.3%) of whom had type 2 diabetes mellitus. The early and long-term results were compared between 277 patients with diabetes using single IMA (SIMA) grafts and 190 using BIMA grafts (median follow-up, 8.1 years). Hospital mortality was similar in both groups. Early patency rate of all grafts was significantly higher using BIMA than using SIMA (97.7% versus 93.8%, P=0.0012). Survival rates were not significantly different between SIMA and BIMA groups. Late cardiac mortality was significantly higher in patients with low ejection fraction (0.4 or lower) compared with preserved ejection fraction (higher than 0.4) (P=0.0001). In patients with preserved ejection fraction, 10-year survival rate was significantly higher using BIMA than using SIMA (87.8+/-3.5% versus 75.2+/-3.4%, P=0.04), and 10-year all death-free or repeat CABG or recurrent myocardial infarction-free rate was significantly higher using BIMA than using SIMA (86.6+/-3.6% versus 69.0+/-3.7%, P=0.0086). The hazard ratio for all death or repeated CABG or recurrent myocardial infarction in patients with preserved ejection fraction was markedly lower in the BIMA group (0.53; 95% CI, 0.31 to 0.9; P=0.019). CONCLUSIONS: Skeletonized BIMA grafts are beneficial in coronary revascularization for diabetic patients with preserved ejection fraction but have limited survival benefit for those with reduced ejection fraction attributable to high cardiac mortality.

Cohort Studies↗
PubMed2003

Left ventricular mass index reduction early after an isolated aortic valve replacement with St. Jude Medical 19A-HP.

OBJECTIVES: It has been reported that the left ventricular mass index (LVMI) for the hypertrophic myocardium is reduced at an early stage following surgery. In this study, those factors affecting the changes in early postoperative LVMI were investigated in cases in which a St. Jude Medical 19A-HP (19HP) mechanical heart valve was used. METHODS: We studied 16 consecutive patients with pure aortic stenosis undergoing isolated aortic valve replacement using a 19HP between January 1994 and July 2001. The patients were all female, aged 64 +/- 6 years, with a body surface area of 1.44 +/- 0.10 m2 and preoperative New York Heart Association (NYHA) classification of 2.2 +/- 0.5. All patients underwent transthoracic echocardiography at 4.2 +/- 3.3 days before and 16.3 +/- 10.2 days after operation, and cardiac catheterization within a mean period of one month before operation. The correlations between the decrease of LVMI at 16.3 +/- 10.2 days after operation and perioperative parameters were determined. RESULTS: There was significant LVMI regression postoperatively (15 +/- 12%, p = 0.01), and only a significant negative correlation between the decrease of LVMI and preoperative left ventricular pressure (LVp) [r = -0.74, p < 0.01]. There was no effective LVMI reduction in the high preoperative LVp group (> or = 210 mmHg). CONCLUSION: It is expected that in the high LVp group, huge wall stress was being applied to the left ventricular muscle immediately before surgery and in the early period after surgery. Preoperative LVp is an important index for determining the surgical timing and safe perioperative management. We recommend early surgical treatment before LVp becomes more than 210 mmHg.

Aged↗
PubMed2003

Angiographic findings and surgical treatments of coronary artery involvement in Takayasu arteritis.

BACKGROUND: Takayasu arteritis is associated with a low incidence of coronary artery involvement, such as stenosis, obstruction, aneurysm, and coronary steal syndrome, but coronary ischemia can be fatal. METHODS: Between 1972 and April 2001, 81 of 130 patients given a diagnosis of Takayasu arteritis underwent selective coronary angiography, and among them, 31 patients (4 male and 27 female patients; mean age, 41.1 +/- 13.2 years) had abnormal coronary angiographic findings and were recruited for this study. RESULTS: Abnormal coronary findings consisted of 24 coronary artery stenoses of greater than 75%, 3 coronary artery-bronchial artery anastomoses, 3 aneurysmal coronary ectasias, and 1 combined coronary ectasia and anastomosis. Among 24 patients with coronary stenosis, the ostium was most frequently involved (87.5%). Twenty-three of 24 patients with coronary artery stenoses were treated surgically. The mean follow-up duration was 9.65 +/- 6.9 years, with a 100% follow-up rate. Four fistulas and 4 aneurysms in 7 patients were not treated surgically. Coronary steal phenomenon was always associated with occluded pulmonary arteries and pulmonary hypertension. Aneurysmal coronary ectasia was related to severe aortic hypertension with or without aortic regurgitation and atypical coarctation. There were 2 (8.7%) in-hospital deaths and 3 (13%) late deaths. The actuarial survival rate, including in-hospital deaths, was 86.5% +/- 7.3% at 5 years and 81.4% +/- 8.4% at 10 years. CONCLUSION: The incidence of coronary abnormalities is relatively low in patients with Takayasu arteritis; however, surgical treatment is recommended for patients with coronary ostial stenoses because coronary ischemia can be one of the major causes of death.

Actuarial Analysis↗
PubMed2003

Urinary trypsin inhibitor improves peripheral microcirculation and bronchospasm associated with systemic anaphylaxis in rabbits in vivo.

Using intravital microscopy of the rabbit ear for quantitative studies of microvascular dynamics, we examined the impact of urinary trypsin inhibitor (UTI), a proteolytic enzyme inhibitor, on microvascular changes during immune complex-mediated anaphylaxis. A total of 50 rabbits, previously sensitized with horse serum, were anesthetized and mechanically ventilated with pentobarbital and isoflurane for the intravital microscopy. Rabbits were then challenged with intravenous injection of horse serum to induce systemic anaphylaxis. One minute after the challenge, each rabbit was randomly assigned to receive saline (group C), 50,000 units x kg(-1) of UTI (group U1), or 150,000 units x kg(-1) (group U2). There were no statistical differences between hemodynamic variables, including heart rate (HR), mean arterial pressure (MAP), and central venous pressure (CVP), among the survivors in each treatment group. Peak inspiratory pressure rose in all three groups but at a much higher rate in group C (P < 0.05). In contrast with the moderate effects of UTI on the above parameters, microscopic evaluation revealed a substantial difference among treatment groups: upon the initiation of anaphylaxis, the arteriole started to reduce in diameter, but UTI prevented vasoconstriction in the arteriole in a dose-dependent manner. Similar results were observed with blood flow velocity. Because flow rate was calculated as the product of blood flow velocity and vascular cross-sectional area proportional to the square of the vessel diameter, these results indicate that UTI preserves microvascular flow rate during anaphylaxis. Rabbit ear microcirculation is highly preserved in the UTI-treated groups during systemic anaphylactic shock.

Anaphylaxis↗
PubMed2002

Acute occlusion of coronary artery bypass graft with nonionic contrast medium.

The use of nonionic contrast media should be beneficial in patients with cardiac disease because such media are less chemotoxic. Using iopamidol under heparinization, we treated 4 cases of acute thromboembolic occurrence including occlusion of coronary artery bypass grafts and associated native coronary arteries. While the majority of patients do not experience this complication, care must be taken to avoid major adverse effects.

Aged↗