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T Kajiyama

Publications and source records attributed to T Kajiyama.

35 records · Page 2Linked to original sources

[Clinical evaluation of endoscopic variceal ligation (EVL)].

From August 1992 through February 1993, we treated 21 patients with endoscopic variceal ligation (EVL). Two patients had a history of the esophageal variceal bleeding, but 19 patients did not have bleeding episodes. To evaluate preventive effect of bleeding, we selected the patients who had grade F2 or red color sign positive varices. We repeated EVL until varices improved into grade F0 or F1 and red color sign negative. The therapeutic goal was sometimes changed according to patient's general condition. No additional therapy was performed to eradicate varices, such as endoscopic injection sclerotherapy. As a result of our therapy, eradication rate was 73.7% and period of hospitalization were 25 +/- 11 days. No major complications were found during and after EVL. EVL affected neither liver function test nor size of gastric varices. Recurrent varices with red color sign were found in 4 patients, but easily controlled by retreatment with EVL. EVL seems to be convenient and effective therapy in our short-term study, and useful for preventive therapy of the esophageal variceal bleeding.

Aged↗

Effect of polyurethane surface chemistry on its lipid sorption behavior.

The relationships among surface, bulk properties and lipid sorption behaviors of segmented polyurethanes (SPUs) with various polyol soft segments were investigated. The polyols used in this study were poly(ethylene oxide) (PEO), poly(tetramethylene oxide) (PTMO), and poly(dimethylsiloxane) (PDMS). The hard segment of these segmented polyurethanes was composed of 4,4'-diphenylmethane diisocyanate and 1,4-butanediol, present at 50 wt%. X-ray photoelectron spectroscopic (XPS) and dynamic contact angle measurements were carried out in order to analyze the surface chemical structure in the air- and water-equilibrated states. XPS revealed that in the air-equilibrated state, lower surface free energy components were enriched at the air-solid interface, whereas in the water-equilibrated state, higher surface free energy components were enriched at the water-solid interface. The change in environment from air to water induced the surface reorganization in order to minimize interfacial free energy. Lipid sorption behaviors of SPUs were investigated by means of infrared spectroscopy. Even after extensive rinsing of the surface, the amount of lipid present on the SPU surface was more than that calculated on the assumption that a monolayer covers the SPU surface. Therefore, the lipid was not only adsorbed on the surface of SPU but absorbed into SPU. The SPU with hydrophilic PEO sorbed larger amount of phospholipid compared with that with hydrophobic polyol such as PTMO and PDMS. Also, the competitive sorption behaviors of phospholipid and cholesterol from their mixed liposome solution were studied. The ratio of sorbed cholesterol to phospholipid increased with an increase in surface hydrophobicity owing to the hydrophobic nature of cholesterol.

Absorption↗

[Endosonographic diagnosis of metastatic tumors in the recto-uterine or recto-vesical space by transrectal scan].

A 6-year experience of transrectal ultrasonography (TRUS) in 75 patients with advanced gastrointestinal cancers was reviewed regarding the diagnostic yield of metastatic extrarectal tumors. A diagnostic capability of TRUS (a sensitivity of 82.9%, a specificity of 97.5% and an accuracy of 90.7%) was statistically superior to that of digital rectal examination (a sensitivity of 62.9%, a specificity of 75% and an accuracy of 69.3%). However, TRUS could hardly correctly diagnose a miliary type of extrarectal tumors in contrast to nodular and thickened types. TRUS also had an advantage over conventional ultrasonography in detecting a small amount of ascites with a sensitivity of 75%, a specificity of 93% and an accuracy of 86.6%. Patients with positive signs of extrarectal tumors or ascites on TRUS survived significantly shorter than those with negative signs. TRUS renders a convenient means in the objective diagnosis of peritoneal carcinomatosis, and predicts patient's prognosis.

Adult↗

Surface properties and platelet reactivity of segmented poly(etherurethanes) and poly(etherurethaneureas).

Segmented poly(etherurethanes) (SPUs) and segmented poly(etherurethaneureas) (SPUUs) with various hard and soft segment components were prepared. The surface characterization of SPUs and SPUUs in the air-equilibrated state and in the hydrated-state was carried out by means of X-ray photoelectron spectroscopic (XPS) and dynamic contact angle measurements. XPS revealed that in the air-equilibrated state, lower surface free energy components were enriched at the air-solid interface, whereas in the hydrated-state higher surface free energy components were enriched at the water-solid interface. The change in environment from air to water induced the surface reorganization in order to minimize interfacial free energy. The large contact angle hysteresis was observed for SPUs and SPUUs. This hysteresis can be mainly ascribed to the surface reorganization process. Platelet adhesion tests on SPU and SPUU surfaces indicated that the existence of surface microphase separated structure played an important role in the attainment of blood compatibility.

Adsorption↗

Surface molecular mobility and platelet reactivity of segmented poly(etherurethaneureas) with hydrophilic and hydrophobic soft segment components.

Segmented poly(etherurethaneureas) (SPUUs) with hydrophilic and hydrophobic polyether components were prepared. The surface chemical composition of SPUUs in various environments was investigated by means of X-ray photoelectron spectroscopic and dynamic contact angle measurements. These measurements revealed that in a hydrated state, the higher surface free energy component is enriched on the surface of the SPUU in order to minimize the interfacial free energy between water and the solid surface. The surface molecular mobility showed a strong correlation with bulk molecular motion. Platelet adhesion tests and dynamic contact angle measurements after adsorption of bovine serum albumin revealed that the surface of SPUUs with hydrophilic soft segments has a non-adhesive nature. The platelet reactivity of hydrophobic SPUUs is influenced by microphase separation at the surface.

Biocompatible Materials↗

Effect of aggregation state of hard segment in segmented poly(urethaneureas) on their fatigue behavior after interaction with blood components.

Characterization of microphase separated structure, interaction with blood components, such as lipids, and fatigue behavior after immersion in blood components were carried out for segmented poly(urethaneureas). The materials studied were Biomer and segmented poly(urethaneurea) (TU-Mn) composed of hard segment with 4,4'-diphenylmethane diisocyanate (MDI)-ethylenediamine (EDA) or 4,4'-diaminodiphenylmethane (DAM) and soft segment with MDI-polytetramethylene glycol (PTMG) [Mn of 856, 1350, and 2000]. Small-angle x-ray scattering, wide-angle x-ray diffraction, and dynamic viscoelastic measurements revealed that these materials showed the state of microphase separation. TU-Mn with PtMG of Mn = 856 shows the partial phase mixing between hard and soft segments, and phase separation was improved with an increase of Mn of PTMG. Biomer has the characteristics of stronger aggregation of hard segment than that of TU-Mn. All the specimen showed lipid absorption, but the amount of absorption decreased remarkably after precoating on the specimen surface with serum albumin. Lipid absorption of the specimen was confirmed by dynamic viscoelastic and IR measurements. In the case of segmented poly(urethaneurea) which did not immersed in lipids solution, their fatigue strength are sufficient for application to artificial heart systems. However, fatigue strength of the TU-Mn series was decreased drastically after absorption of lipids. On the other hand, Biomer did not show a decrease of fatigue strength after lipid absorption. The reduction of fatigue strength in the TU-Mn series after lipid absorption will be attributed to the weak aggregation of hard segment domain. This reduction of fatigue strength in the TU-Mn series is characterized by formation of microcrack and mirror zone in fatigue fractured specimen. As the precoating of the specimen surface with serum albumin inhibits the absorption of lipids, the reduction of fatigue strength was not observed for the specimen precoated with serum albumin even after immersing the TU-Mn series in lipids solution for 96 days.

Absorption↗