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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 163 records · Page 9Linked to original sources
PubMed1998

Guinea pig liver Mu-class glutathione S-transferase M1-2 cross-reacts with antibodies to both rat Mu- and theta-class glutathione S-transferases.

Two novel major heterodimeric Mu-class glutathione (GSH) S-transferases (GSTs), designated M1-2 and M1-3*, were isolated from guinea pig (gp) liver cytosol and purified to homogeneity together with a known major homodimeric Mu-class gpGSTM1-1 (reported as GST b by R. Oshino, K. Kamei, M. Nishioka, and M. Shin, 1990, J. Biochem. 107, 105-110). These three gpGSTs were quantitatively retained on an S-hexyl-GSH affinity column and separated as homogeneous proteins by chromatofocusing. Subunits of the heterodimers were inseparable on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but could be completely separated by reverse-phase partition high-performance liquid chromatography. A molecular cloning study demonstrated that the gpGST subunit M2 consisted of 217 amino acid residues with a calculated molecular mass of 25,562 and shared 84% identity in overall amino acid sequence with gpGSTM1-1. N-terminal amino acid sequences of peptides from the gpGST subunit M3* with a blocked N-terminus strongly suggested that it should belong to the Mu class. Western blot analysis using antisera raised against purified rat (r) GSTsA1-2 (Alpha), M1-1, P1-1 (Pi), and T2-2 (Theta) indicated that gpGSTsM1-1 and M1-3* cross-reacted only with anti-rGSTM1 antibody. However, gpGSTM1-2 cross-reacted intensely to almost the same extent with antibodies to both rGSTsM1-1 and T2-2. A homodimeric gpGSTM2-2, artificially constructed from native gpGSTM1-2 by treatment with guanidine hydrochloride followed by dialysis, intensely cross-reacted with antibodies to both the rat Mu- and Theta-class GSTs. Thus, the gpGST subunit M2 provided the first evidence for the double immuno-cross-reaction of a GST with polyclonal antibodies to two different classes of GSTs.

Amino Acid Sequence↗
PubMed1998

Characterization and interpretation of the quantum efficiencies of multilayer semiconductor detectors using a new theory.

On the basis of a new theory of semiconductor X-ray detector response, a new type of multilayer semiconductor detector was designed and developed for convenient energy analyses of intense incident X-ray flux in a cumulative-current mode. Another anticipated useful property of the developed detector is a drastic improvement in high-energy X-ray response ranging over several hundred eV. The formula for the quantum efficiency of multilayer semiconductor detectors and its physical interpretations are proposed and have been successfully verified by synchrotron radiation experiments at the Photon Factory. These detectors are useful for data analyses under strong radiation-field conditions, including fusion-plasma-emitting X-rays and energetic heavy-particle beams, without the use of high-bias applications.

Journal Article↗
PubMed1998

Risk factors for hyperamylasemia after hepatectomy using the Pringle maneuver: randomized analysis of surgical parameters.

OBJECTIVES: To determine whether the increased portal venous pressure caused by use of the Pringle maneuver contributes to inducing posthepatectomy hyperamylasemia and, subsequently, to evaluate risk factors for its development. DESIGN: Randomized study. SETTING: University hospital. PATIENTS: Forty patients who were going to undergo hepatectomy were assigned prospectively to either a superior mesenteric artery clamp (n=20) or a nonclamp (n=20) group by the random-block method. INTERVENTIONS: The Pringle maneuver was used during hepatectomy, and in the superior mesenteric artery clamp group the superior mesenteric arteries were clamped simultaneously. MAIN OUTCOME MEASURES: Amylase activity, isozyme, and creatinine levels in the blood and urine samples were measured before and after surgery, and the amylase creatinine clearance ratio was estimated. RESULTS: The serum amylase activity levels of the superior mesenteric artery clamp and nonclamp groups did not differ significantly during the 7 postoperative days. The serum amylase activity levels exceeded 250 U/L in 14 patients (group 1) and remained below this level in 26 (group 2). The salivary-type isozyme levels of group 1 increased significantly compared with those of group 2, and the levels of group 2 remained normal. The total amount of amylase excreted in the urine samples of group 1 patients also increased significantly, with the salivary-type isozyme predominating. All the mean amylase creatinine clearance ratios before and after surgery remained normal. The mode chi2 of the logistic model including the indocyanine green retention rate at 15 minutes and the ratio of the resected liver weight to the whole liver volume showed a significantly increased risk (P=.01). CONCLUSION: It is not the increased portal venous pressure caused by use of the Pringle maneuver but the liver function and the extent of liver resection that are considered risk factors for inducing posthepatectomy salivary-type hyperamylasemia.

Aged↗
PubMed1998

[A case report of aortic valve replacement following ruptured aneurysm of the sinus of Valsalva with bicuspid valve].

Only three cases of the combination of bicuspid aortic valve and ruptured aneurysm of the sinus of Valsalva, associated with previously repaired coarctation of aorta, have been reported. A twenty-year-old man with a sudden onset of CHF due to ruptured aneurysm of the sinus of Valsalva underwent intracardiac repair by direct closure of the sinus Valsalva in combination with patch closure of a subarterial VSD. Although, no AR was detected preoperatively, massive regurgitation occurred after the repair due to subsequent failure of aortic valve coaptation in the present of the bicuspid aortic valve, which was not diagnosed preoperatively. Aortic valve replacement with SJM 25 mm was successfully performed.

Adult↗
PubMed1998

Sodium at high concentrations increases glucose-induced insulin secretion in the perfused rat pancreas.

To study the effects of supraphysiologically high sodium concentrations on insulin secretion, the rat pancreas was perfused with normal Krebs-Ringer bicarbonate buffer (KRBB) solution and with KRBB solutions containing an additional 25 and 50 mmol/l NaCl. The first phase of insulin secretion in response to 18 mmol/l glucose was enhanced in a dose-dependent manner, from 20.8+/-4.0 pmol for 4 min in normal KRBB to 36.2+/-10.3 pmol (P<0.05) and 60.3+/-14.6 pmol (P<0.01) with addition of 25 and 50 mmol/l NaCl, respectively. The second phase secretion was significantly increased by the addition of 50 mmol/l NaCl (259.4+/-38.6 vs 170.9+/-47.4 pmol for 16 min P<0.05). The addition of 50 mmol/l isethionate Na to normal KRBB solution also increased the first and second phases of insulin secretion in response to glucose. The increase in osmolarity by the addition of mannitol to normal KRBB solution did not affect the glucose-induced insulin secretion. A high sodium concentration affected neither tolbutamide-induced nor arginine-induced insulin secretion. It is suggested that sodium concentrations have an important role in insulin secretion in response to glucose, but not to other secretagogues.

Animals↗
PubMed1998

Reconstruction of the hepatic and portal veins using a patch graft from the right ovarian vein.

We describe a patch-graft technique using the right ovarian vein for reconstruction of the right hepatic and portal veins after resection in hepatectomy and pancreatoduodenectomy in female patients. After partial resection of the right hepatic vein or portal vein for removing either hepatic or pancreatic tumors, the defects were covered by a patch graft from the right ovarian vein. The proximal part of the vein, 5 cm in length, was harvested, divided longitudinally, and then divided into two equal parts, which were sutured together to give a patch measuring 2.5 x 2.0 cm. This technique can be applied for reconstruction after partial resection of the hepatic or portal vein in hepatectomy and pancreatoduodenectomy.

Colonic Neoplasms↗
PubMed1998

Placental ecto-ATP diphosphohydrolase: its structural feature distinct from CD39, localization and inhibition on shear-induced platelet aggregation.

Human placental ecto-ATP diphosphohydrolase (ATPDase), an 82 kDa single-chain glycoprotein, was purified to high specific activity using a specific murine monoclonal antibody MK33 (IgG1-kappa). Structurally, protein-based analysis showed this enzyme to be almost identical to that of CD39 lymphoid cell activation antigen deduced by cDNA sequencing (Maliszewski CR, et al, J Immunol 1994; 153:3574); but differing in the NH2-terminal amino acid sequence, suggesting that placental ecto-ATPDase is most likely an isoform of CD39 generated by alternative splicing of the pre-mRNA. Functionally, placental ecto-ATPDase totally inhibits the secondary platelet aggregation induced by agonists at a final concentration (f.c.) of 1 microgram/ml. The purified enzyme (1 microgram/ml, final), pre-incubated with washed platelets prior to alpha-thrombin stimulation, completely inhibits the activation of platelet glycoprotein (GP) IIb/IIIa, thereby blocking the binding of fibrinogen or von Willebrand factor to platelets. Further, under different shear stresses, the enzyme modulates platelet aggregation differently. Low shear stress-induced platelet aggregation is blocked by this enzyme in a dose-dependent manner and is totally blocked at f.c. 0.5 microgram/ml. Under high shear stress, however, this protein at a f.c. of 0.5 microgram/ml mediates almost complete disaggregation of platelets without affecting the initial aggregation. Using immunohistochemical analysis, this enzyme was observed to be localized at the syncytiotrophoblasts of placental microvilli and the endothelial cells (ECs) of the umbilical vein obtained at full-term normal delivery, but scarcely at the ECs of the umbilical artery.

Adenosine Triphosphatases↗
PubMed1998

Ay-4166 increases the sensitivity of insulin secretion to glucose in isolated perfused rat pancreas.

To study the effect of a therapeutic dose (3 microM) of AY-4166 on the glucose-stimulated insulin secretion, the rat pancreas was perfused with 5 to 15 mM glucose. AY-4166 did not affect the basal insulin secretion at 5 mM glucose, and increased the first and second phases of insulin secretion stimulated by 7.5 to 15 mM glucose. The dose-response curve of the insulin secretion to glucose was shifted to the left side by AY-4166. These results suggest that AY-4166 ist not a stimulator releasing insulin independently of glucose concentrations, but a potentiator of insulin secretion.

Animals↗
PubMed1998

A case of congenital mumps infection complicated with persistent pulmonary hypertension.

A low-birth-weight female baby was admitted with respiratory distress after birth. Her mother had been diagnosed with mumps 4 weeks and 5 days prior to delivery. Mumps IgM antibody was elevated in the neonate and mumps virus ribonucleic acid was detected in the umbilical cord blood by reverse transcription-polymerase chain reaction. The perinatal virus infection was complicated with persistent pulmonary hypertension of the newborn and pulmonary hemorrhage. Successful treatment included the use of high frequency oscillation ventilation together with the administration of artificial surfactant.

Antibodies, Viral↗
PubMed1998

Effects of intra-abdominal hypertension on hepatic energy metabolism in a rabbit model.

BACKGROUND: Intra-abdominal hypertension is known to decrease hepatic blood flow, but its effect on hepatic energy level has not described. METHODS: Fifty-three rabbits were mechanically ventilated and divided into five groups. Intra-abdominal hypertension was induced by saline infusion and maintained for 30 minutes. Hepatic sinusoidal functional blood flow was evaluated by means of indocyanine green disappearance rate (ICG-K), hepatic mitochondrial redox status was evaluated by arterial ketone body ratio, and tissue energy level was evaluated by energy charge (EC). RESULTS: At an intra-abdominal pressure of 20 mm Hg, ICG-K was significantly decreased, with no decrease in EC. At 30 mm Hg, hypoxemia developed and the ICG-K decreased further, with significant decreases observed in arterial ketone body ratio and EC. The latter were not increased by administration of oxygen. CONCLUSION: At an intra-abdominal pressure of 20 mm Hg, a slight decrease in sinusoidal flow did not affect hepatic energy level. At 30 mm Hg, a reduced hepatic mitochondrial redox status and a decreased energy level were attributed to a decrease in sinusoidal flow in this animal model.

Abdomen↗