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Biomedical subjects

T Akizawa

Publications and source records attributed to T Akizawa.

At least 37 records · Page 2Linked to original sources
PubMed2000

Characterization of inducible nature of MRP3 in rat liver.

We found previously that expression of multidrug resistance-associated protein (MRP) 3 is induced in a mutant rat strain (Eisai hyperbilirubinemic rats) whose canalicular multispecific organic anion transporter (cMOAT/MRP2) function is hereditarily defective and in normal Sprague-Dawley (SD) rats after ligation of the common bile duct. In the present study, the inducible nature of MRP3 was examined, using Northern and Western blot analyses, in comparison with that of other secondary active [Na(+)-taurocholic acid cotransporting polypeptide (Ntcp), organic anion transporting polypeptide 1 (oatp1), and organic cation transporter (OCT1)] and primary active [P-glycoprotein (P-gp), cMOAT/MRP2, and MRP6] transporters. alpha-Naphthylisothiocyanate treatment and common bile duct ligation induced expression of P-gp and MRP3, whereas expression of Ntcp, oatp1, and OCT1 was reduced by the same treatment. Although expression of MRP3 was also induced by administration of phenobarbital, that of cMOAT/MRP2, MRP1, and MRP6 was not affected by any of these treatments. Moreover, the mRNA level of MRP3, but not that of P-gp, was increased in SD rats after administration of bilirubin and in Gunn rats whose hepatic bilirubin concentration is elevated because of a defect in the expression of UDP-glucuronosyl transferase. However, the MRP3 protein level was not affected by bilirubin administration. Although the increased MRP3 mRNA level was associated with the increased concentration of bilirubin and/or its glucuronides in mutant rats and in SD rats that had undergone common bile duct ligation or alpha-naphthylisothiocyanate treatment, we must assume that factor(s) other than these physiological substances are also involved in the increased protein level of MRP3.

1-Naphthylisothiocyanate↗
PubMed2000

Properties and human origin of two angiotensin-I-converting enzyme inhibitory peptides isolated from a tryptic hydrolysate of human serum albumin.

Two angiotensin-I-converting enzyme (ACE) inhibitory peptides were isolated from a tryptic hydrolysate of human serum albumin (HSA). The peptides were identified by sequencing and other analyses as Ala-Trp and the nonapeptide Ala-Phe-Lys-Ala-Trp-Ala-Val-Ala-Arg (human albutensin A), corresponding to f(213-214) and f(210--218) of HSA, respectively. Synthetic versions of both peptides had previously been shown to have ACE inhibitory activity. The present results are the first to show that these peptides have a potential natural origin in humans. Additional studies were done to define the inhibitory properties of these peptides, as they had not been previously reported. The dipeptide and nonapeptide showed dose-dependent inhibition of ACE, with IC50 values of 12 and 1.7 micromol/l, respectively. Lineweaver-Burk plots suggested that Ala-Trp is a competitive inhibitor, and that human albutensin A is a noncompetitive inhibitor.

Adrenal Cortex↗
PubMed1999

Plasma exchange for acquired hemophilia: a case report.

A patient with acquired hemophilia complicated with chronic renal failure and lung tuberculosis was successfully treated by consecutive plasma exchange (PE). A 71-year-old man with serious bleeding tendency showed low coagulation factor levels and a high titer of factor VIII (FVIII) inhibitor, and he was diagnosed with acquired hemophilia. Because of the complication of active lung tuberculosis, instead of immunosuppressive therapy, he undertook a series of PE with fresh frozen plasma replacement for 3 months. After the start of PE, his bleeding symptoms and activated partial thromboplastin time (APTT) improved gradually according to the decrease in FVIII inhibitor levels. These results suggest that PE is an effective therapeutic tool for refractory acquired hemophilia.

Aged↗
PubMed1999

Effect of plasma exchange on refractory hemophagocytic syndrome complicated with myelodysplastic syndrome.

A case of hemophagocytic syndrome (HPS) refractory to corticosteroid therapy was successfully treated by plasma exchange. The patient was a 56-year-old woman who had undergone regular hemodialysis for 10 years for complicated myelodysplastic syndrome (MDS) and then had had lung tuberculosis. After the onset of tuberculosis, she suffered from HPS and was treated by antituberculosis agents and high dose corticosteroid administration without any effect on the HPS. After adding a series of plasma exchanges, the HPS improved gradually, and her MDS began to respond to corticosteroid therapy. Plasma hypercytokinemia due to HPS was corrected by plasma exchange, and the correction of a high level of plasma inflammatory cytokine was considered to be one of the contributing factors for the improvement of HPS. These results suggest that therapeutic plasma exchange should be considered as a therapeutic tool for HPS refractory to conventional therapy.

Adolescent↗
PubMed1999

A case of factor VIII inhibitor-positive acquired hemophilia treated by plasmapheresis.

We report on a case of factor VIII inhibitor-positive acquired hemophilia in which combined therapy of plasma exchange (PE) and steroids was effective. The patient, a 68-year-old man, had undergone hemodialysis since April 1998, due to chronic renal failure caused by diabetic nephropathy. The hemostasis of blood access sites gradually became difficult after the initiation of dialysis and the prolongation of activated partial thromboplastin time (APTT) (74.5 s), and a decrease in factor VIII (0.02%) and an abnormally high concentration of factor VIII inhibitor (111 U/ml) were found. Under the diagnosis of factor VIII inhibitor-positive acquired hemophilia, 3 consecutive PE were performed, followed by a large dose administration of gamma globulin. However, the effect of this therapy disappeared within 20 days. Then the PE therapy was performed again accompanied by pulse methylprednisolone therapy. After that, factor VIII inhibitor was suppressed and the patient's hemostatic defect continued to improve even after the reduction of the steroid dose. These results suggest that PE is very effective in treating factor VIII inhibitor-positive acquired hemophilia.

Aged↗
PubMed1999

Modulation of parathyroid cell function by calcium ion in health and uremia.

Extracellular calcium ion concentration is the major determinant of parathyroid hormone (PTH) secretion from parathyroid cells. In dialysis patients with secondary hyperparathyroidism, higher calcium concentration is needed to suppress PTH secretion as demonstrated by the PTH-calcium curve. Such abnormal sensitivity to extracellular calcium ion has been recently explained by the decrease in number of calcium-sensing receptors, especially on cells in nodular hyperplasia, which is the advanced type of parathyroid hyperplasia in uremia. Modulation of the sensitivity of parathyroid cells to calcium has become partly possible through the use of newly developed calcimimetics.

Calcium↗
PubMed1998

Development of guanine analyzer to measure activity of guanylate cyclase.

A previous analyzer of adenine compounds by high-performance liquid chromatography was converted for the determination of guanine, its nucleoside and nucleotides by a post-column fluorescence derivatization with phenylglyoxal (PGO) in place of bromoacetoaldehyde. The gel filtration column (Asahipak GS-320H) was used for separation by a mobile phase consisting of 25 mM sodium citrate buffered (pH 4.0)-150 mM NaCl solution and CH3CN (85:15, v/v) containing 15 mM PGO. The separated analytes reacted with flow through PGO in a reaction coil at 90 degrees C into fluorescent derivatives. Those derivatives were detected fluorimetrically, highly selective and quantitatively. The activity of soluble guanylate cyclase (sGC) in the neuroblastoma N1E-115 cell was measured by tracing the peak height of cGMP synthesized from substrate GTP using this guanine analyzer. The sensitivity of the present method was lower than the radioisotope method. However, our modified method was simpler, safer and quicker than the radioisotope method. Furthermore, this method could trace other guanine compounds simultaneously, allowing measurement of guanine metabolizing enzymatic activity. Therefore, it will be useful for screening of effectors on sGC.

Chromatography, Gel↗