Search PubMed⌕ Search

Biomedical subjects

S Motohashi

Publications and source records attributed to S Motohashi.

35 records · Page 2Linked to original sources
PubMed1996

[Protein binding of clarithromycin in patients with chronic renal failure].

Assessment was made on the serum protein binding of clarithromycin (CAM), a representative oral macrolide, using sera from healthy subjects (HS) and patients with chronic renal failure (CRF) applying equilibrium dialysis in vitro. The protein binding of CAM was 81.9 +/- 1.9%, 85.9 +/- 3.6%, 82.9 +/- 3.3% and 86.8 +/- 3.3% for sera from HS, from patients in conservative treatment (ND), from those receiving hemodialysis (HD) and from those with continuous ambulatory peritoneal dialysis (CAPD), respectively. There was no significant difference among these values. The protein binding of CAM was 82.9 +/- 3.3% and 68.8 +/- 3.5% for sera before and after HD, respectively. There was significant difference between these values. In the study of the protein binding in patients on HD at an albumin concentration of 0.5 mM, the protein binding of CAM for sera was found to be significantly decreased following HD as compared to that prior to HD. The addition of palmitic acid (PA), a common NEFA, to pooled sera from HS, the protein binding of CAM showed no change. These findings suggest that changes in the protein binding of CAM with HD have been possibly caused by an increase in a drug binding inhibiter other than NEFA (PA) or by an allosteric effect on the albumin binding capacity. At therapy using CAM, the possibility of enhanced pharmacological effects and increased adverse reactions of CAM due to decreased protein binding in patients on HD should be considered.

Anti-Bacterial Agents↗
PubMed1995

Regulation of inducible nitric oxide production by cytokines in human thyrocytes in culture.

We now report on the induction and modulation of NO production by cytokines in primary cultures of human thyrocytes and the effect of NO on iodine organification by human open thyroid follicles in the process of thyroid hormone biosynthesis. Although unstimulated thyrocytes produced little NO (measured as nitrite), interleukin-1 alpha or beta (IL-1 alpha/beta) substantially increased NO formation. Interferon-gamma (IFN-gamma) by itself failed to stimulate NO formation but markedly increased the IL-1-stimulated NO production. Tumor necrosis factor-alpha alone did not induce NO production but did so slightly in the presence of IFN-gamma. Induction of NO formation by thyrocytes upon stimulation with IL-1 alpha + IFN-gamma was accompanied by the synthesis of tetrahydrobiopterin (BH4), an obligatory cofactor of NOS. Coinduction of NO and BH4 synthesis in thyrocytes was preceded by coexpression of messenger RNAs for NOS and GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme for de novo synthesis of BH4. NO synthesis was prevented by an inhibitor of GTPCH, 2,4-diamino-6-hydroxypyrimidine, and this inhibition was completely reversed by administration of sepiapterin, a substrate for BH4 synthesis via pterin salvage pathway. In contrast to IFN-gamma, some cytokines such as interferon-alpha, IL-4, and transforming growth factor-beta 1 inhibited the IL-1-induced NO production. Finally, a possible role of NO on thyroid hormone synthesis was investigated. Iodine organification by human open thyroid follicles was inhibited by two kinds of NO donor but not by cell permeable cyclicGMP analog. Thus, cytokines such as IL-1, IL-1/IFN-gamma, and tumor necrosis factor-alpha/IFN-gamma stimulate human thyrocytes to produce NO; this process can be modulated by other cytokines and coregulated with a cofactor BH4 biosynthesis, and resulting NO may affect cell function including thyroid hormone synthesis.

Amino Acid Oxidoreductases↗
PubMed1993

[Protein binding of oral cephems in patients with chronic renal failure].

An assessment was made of the serum protein binding of representative oral cephems (cefdinir, cefixime and ceftibuten) for sera from healthy subjects (HS) and patients with chronic renal failure (CRF) using an application of equilibrium dialysis under a same set of conditions in vitro. The protein binding capacity of oral cephems in CRF patients being treated with continuous ambulatory peritoneal dialysis (CAPD) or hemodialysis (HD) was significantly less than that in HS, and a marked increase in free drug concentration was observed. While examining the protein binding of oral cephems with heparin in patients on HD, binding capacity decreased significantly immediately following the completion of dialysis compared to that prior to dialysis. On the other hand, the protein binding of oral cephems did not change when used nafamostat mesilate as an anticoagulant. The addition of palmitic acid (PA), a common non-esterified fatty acid (NEFA), to pooled sera from HS caused the binding capacity of oral cephems to decrease, accompanied by increase in PA concentration. It appears from these findings that changes in the binding capacity of oral cephems with HD have possibly been caused by increase in NEFA due to activation of lipase when heparin was used as an anticoagulant. In conclusion, changes in the protein binding capacity of oral cephems in CRF patients should be taken into consideration in attempts to avoid possible side effects.

Carrier Proteins↗
PubMed1992

[Protein binding of cephems in the elderly].

The serum protein-binding of 12 representative cephems (CET, CEZ, CZX, CPZ, CZON, CPM, CDZM, CFX, CMZ, CTT, LMOX, FMOX) was assessed, using sera from young healthy subjects (mean age, 28.6 years old) and elderly healthy subjects (mean age, 69.7 years old), applying equilibrium dialysis under the same conditions in vitro. The protein-binding capacity of 12 cephems in elderly subjects was significantly less than that in young subjects, and marked increase in free drug concentration was observed in elderly subjects. This decrease in the protein binding capacity of cephems in elderly subjects was possibly caused by decreased serum albumin and change in non-esterified fatty acid constitution related to aging. As free-drug concentration participates in the appearance of effects and adverse reactions, the possibility of an enhanced pharmacological effects and increased adverse reactions of cephems due to decrease of protein binding in elderly subjects should be considered.

Adult↗
PubMed1991

[A case of anti-myeloperoxidase antibodies-associated idiopathic crescentic glomerulonephritis with pulmonary hemorrhage].

We report a case of idiopathic crescentic glomerulonephritis with pulmonary hemorrhage associated with anti-myeloperoxidase antibodies (anti-MPO ab). A 74 year-old female was admitted to our hospital because of rapidly progressive glomerulonephritic syndrome and dyspnea with bloody sputum. On admission anti-MPO ab, one of anti-neutrophil cytoplasmic antibodies, were detected but anti-GBM antibodies and immune complexes were not detected. Renal biopsy showed crescentic glomerulonephritis and lung biopsy showed massive alveolar hemorrhage. Both tissue had pauci-immune deposit by immunofluorescence microscopy. Hemodialysis and steroid administration were started. Pulmonary hemorrhage was improved remarkably, but renal failure progressed rapidly to end stage kidney, then hemodialysis was continued. Although subsequent 3 years uneventful maintenance hemodialysis had been performed, she admitted to our hospital again because of progressive dyspnea with hemoptysis after upper respiratory tract infection. On admission anti-MPO ab were detected again and steroid administration was started. Pulmonary hemorrhage was improved with decreased anti-MPO ab titer. While tapering the dosis of steroid, anti-MPO ab again increased and pulmonary hemorrhage recurred. Although pulse methylprednisolone therapy and plasma exchange were performed, respiratory failure progressed rapidly and she died of sepsis. Postmortem examination showed no evidence of systemic vasculitis. In this case, titer of anti-MPO ab was associated with not only idiopathic crescentic glomerulonephritis but also with pulmonary hemorrhage. We tried to detect enzymatically active MPO in serum. Titer of serum MPO was also associated with disease activity and anti-MPO ab. It is suggested that both anti-MPO ab and serum MPO are closely related to the pathogenesis of idiopathic crescentic glomerulonephritis and pulmonary hemorrhage.

Aged↗
PubMedDate not supplied

The role of alpha-galactosylceramide-activated Valpha14 natural killer T cells in the regulation of Th2 cell differentiation.

Valpha14 natural killer T (NKT) cells produce large amounts of both IL-4 and IFN-gamma upon stimulation with a ligand, alpha-galactosylceramide (alpha-GalCer), and play a crucial role in various immune responses, including allergic diseases. Interestingly, Valpha14 NKT cells are not essential for the induction of IgE responses but rather induce suppression of specific IgE production upon activation. The suppression in the IgE production is not detected either in Valpha14 NKT cell-deficient mice or in IFN-gamma-deficient mice. Thus, activated Valpha14 NKT cells are likely to exert a potent suppressive activity on Th2 cell differentiation and subsequent IgE production by producing a large amount of IFN-gamma. In marked contrast, little regulatory effect of IL-4 produced by Valpha14 NKT cells on Th2 cell differentiation is suggested.

Animals↗