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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 541 records · Page 30Linked to original sources
PubMedDate not supplied

Excessive portal flow causes graft nonfunction in small size liver transplantation: an experimental study in pigs.

We investigated the effects of portocaval shunt (PCS) on excessive portal flow in producing sinusoidal microcirculatory injury in small-for-size liver transplants in pigs. The posterior segment of a whole liver (25%) was transplanted orthotopically. The pigs were divided two groups: group A, graft with PCS (n = 11), and group B, graft without PCS (n = 11). The PCS was a side-to-side anastomosis of the portal vein and the inferior vena cava. In group A, eight pigs survived for more than 4 days; all pigs except for one died of graft nonfunction within 24 hours in group B. The portal flow after reperfusion decreased in group A, but increased about three times greater in group B than that before the operation (P < .01). In group B, destruction of the sinusoidal lining and bleeding in the periportal areas were observed after reperfusion, findings that were not recognized in group A. These results suggest that graft nonfunction after small-for-size liver transplantation may be attributable to excessive portal flow producing sinusoidal microcirculatory injury.

Animals↗
PubMedDate not supplied

Structural analysis of silk with 13C NMR chemical shift contour plots.

The polymorphic structures of silk fibroins in the solid state were examined on the basis of a quantitative relationship between the 13C chemical shift and local structure in proteins. To determine this relationship, 13C chemical shift contour plots for C alpha and C beta carbons of Ala and Ser residues, and the C alpha chemical shift plot for Gly residues were prepared using atomic co-ordinates from the Protein Data Bank and 13C NMR chemical shift data in aqueous solution reported for 40 proteins. The 13C CP/MAS NMR chemical shifts of Ala, Ser and Gly residues of Bombyx mori silk fibroin in silk I and silk II forms were used along with 13C CP/MAS NMR chemical shifts of Ala residues of Samia cynthia ricini silk fibroin in beta-sheet and alpha-helix forms for the structure analyses of silk fibroins. The allowed regions in the 13C chemical shift contour plots for C alpha and C beta carbons of Ala and Ser residues for the structures in silk fibroins, i.e. Silk II, Silk I and alpha-helix, were determined using their 13C isotropic NMR chemical shifts in the solid state. There are two area of the phi,psi map which satisfy the observed Silk I chemical shift data for both the C alpha and C beta carbons of Ala and Ser residues in the 13C chemical shift contour plots.

Alanine↗
PubMedDate not supplied

Fibroma of the vulva.

We describe a patient with fibroma of the vulva. The tumor had areas of marked hypointensity consistent with fibrosis on T1 and T2 weighted magnetic resonance (MR) images. The presence of abundant fibrous tissues on MR images enabled us to make a preoperative diagnosis of fibroma.

Adipose Tissue↗
PubMedDate not supplied

The use of an oxygen dissociation curve analyzer in transfusion therapy.

Two automatic apparatuses utilizing a dual wave-length spectrophotometric method were developed to perform oxygen dissociation curves on microsamples of blood. This method provides a complete printout of an oxygen dissociation curve in 15 to 20 minutes and the P50 values obtained agree closely with those obtained by classical methods. This technique was used as part of a routine clinical evaluation in assessing oxygen delivery in anemic patients. These apparatuses allowed identification of patients with well-compensated anemia, patients with no compensatory decrease in oxygen affinity, and several patients with a paradoxical increase in oxygen affinity. Knowledge of the oxygen-releasing capacity of the blood permits a more thorough evaluation of oxygen transport in anemic patients than the hemoglobin level and a more precise assessment of the need for transfusion therapy. The ready availability of an oxygen dissociation curve by this method is feasible for routine clinical evaluation and permits more judicious use of blood products.

Anemia↗
PubMedDate not supplied

Feline adult beta-globin polymorphism reflected in restriction fragment length patterns.

Adult domestic cats (Felis catus) appear to have the most polymorphic beta-globin system of any species. Reversed-phase high-performance liquid chromatography (RP-HPLC) revealed one alpha-chain and six different beta-globin chains. Each cat may have one to four different beta-globins, and a total of 17 different beta-globin patterns were identified. Based on family studies, a beta-globin gene region with two linked beta-globin gene loci and two to five alleles was proposed. In order to further define the molecular basis of this polymorphism we performed Southern blot analysis of the beta-globin gene region from 25 cats with 13 different HPLC patterns. Genomic DNA was digested with five restriction endonucleases (BamHI, BglII, EcoRI, HindIII, and PstI) and blots were hybridized with a human beta-globin probe. Restriction fragment length polymorphisms (RFLPs) with one to five fragments of 2.2-23 kb in size were found with BglII, EcoRI, HindIII, and PstI. Cats with specific HPLC beta-globin patterns had a unique DNA restriction pattern. The similarly sized BamHI and HindIII fragments of 4.6 kb suggest the presence of two closely linked genes. Furthermore, family studies suggest an autosomal codominant mode of inheritance of the beta-globin chains with seven haplotypes. Thus the RFLP data analyzed in the context of the HPLC haplotypes provide evidence at the DNA level for a feline beta-globin gene region with two closely linked gene loci and two to five alleles.

Animals↗
PubMedDate not supplied

Pharmacokinetic profile of the anti-sickling hydroxyurea in wild-type and transgenic sickle cell mice.

The pharmacokinetic profile of hydroxyurea (HU) was investigated by measuring the rate of drug disappearance from the plasma in wild-type and transgenic (Tg) sickle cell mice. The absorption and elimination processes of HU exhibited first-order kinetics after intraperitoneal administration of HU at 10, 50, 100 or 200 mg/kg body weight (BW). The dosage had a marked effect on the pharmacokinetics of HU in the Tg sickle cell mice. Although the area under the plasma concentration curve (AUC) increased in direct proportion with the HU dose in the wild-type mice, the AUC increased to a much greater extent at higher doses in the Tg sickle cell mice. In the Tg sickle cell mice, there was a considerable increase in the mean residence time (MRT) and a significant reduction in the apparent clearance (CL/F) at HU dose > or =100 mg/kg BW, when compared to the lower doses. At an HU dose of 200 mg/kg BW, the CL/F in the Tg sickle cell mice was reduced by about 50% of the value obtained at a dose of 10 mg/kg BW. This phenomenon was not noticeable in the wild-type mice. The MRT value in the wild-type mice at all doses was relatively constant. The steady-state distribution volume of HU in both the wild-type and Tg sickle cell mice was relatively constant at all doses of the drug. The AUC, CL/F, MRT, and terminal half-life values at any given HU dose showed significant differences between the wild-type and Tg sickle cell mice. Following intraperitoneal administration of HU at a dose of 10, 50, 100, or 200 mg/kg BW, the mean percentage of HU excreted in the urine of the wild-type and Tg sickle cell mice over 120 min was 84 +/- 6.4% and 50 +/- 8.2%, respectively, indicating a significant difference in the amount of HU excreted in urine in the two kinds of mice. The results obtained in this study may be useful in establishing an optimal dose of HU in the treatment and management of patients with sickle cell disease and other hemoglobinopathies.

Anemia, Sickle Cell↗
PubMedDate not supplied

Primary hepatic carcinoid tumor: a case report.

A case of primary hepatic carcinoid tumor is reported. A 57-year-old woman had no endocrine symptoms. Light microscopic findings revealed tumor cells forming trabecular or insular structures and demonstrating diffuse positive staining by the Grimelius method. Mucin stained with Periodic acid-Schiff (PAS) and alcian-blue was partially present in the tumor cells. Immunohistochemically, most tumor cells stained positive with chromogranin A and cytokeratin stains. Intensive and careful investigation before and after the operation revealed no other origin of the tumor. We present this rare case, describe the clinical features of hepatic carcinoid, and discuss its diagnosis.

Biomarkers, Tumor↗
PubMedDate not supplied

MR imaging of various oxidation states of intracellular and extracellular hemoglobin.

The in vitro behavior of various states of hemoglobin was examined over a wide range of concentrations. Solutions of increasing concentrations of oxyhemoglobin displayed significant increases in T1 and T2 relaxation rates that were insensitive to pH values between 6.0 and 6.9. Bovine serum albumin, which displayed a relaxation behavior nearly identical to that of oxyhemoglobin, was used to normalize for the protein concentration of the deoxyhemoglobin and methemoglobin samples. Concentrated protein solutions with increasing proportions of deoxyhemoglobin yielded little change in the T1 relaxation rate. In these samples, however, the T2 relaxation rate displayed a parabolic dependence on the concentration of intracellular deoxyhemoglobin paralleling the inhomogeneity of the sample; this was not observed with extracellular deoxyhemoglobin. Similar T2 relaxation behavior was observed for intracellular methemoglobin, except that the magnitude of the T2 shortening was smaller than that for deoxyhemoglobin. The magnitude of the T2 shortening was pH dependent, roughly paralleling the change in the equilibrium between the high-spin acid form of methemoglobin and the low-spin basic form of methemoglobin. Marked increase in the T1 relaxation rate is observed with increasing concentrations of methemoglobin, again with greater relaxation enhancement at lower pH. The results of our study emphasize the importance of normalizing for protein concentration when assessing the effects of paramagnetic forms of hemoglobin.

Extracellular Space↗