Akio Tanaka

Publications (7)13.78 Total impact

• Article: [The case to the patient with renal insufficiency].

  Akio Tanaka, Hideaki Shimizu, Seiichi Matsuo
  Nippon rinsho. Japanese journal of clinical medicine 08/2012; 70 Suppl 6:353-64.
• Article: Peritonitis is still an important factor for withdrawal from peritoneal dialysis therapy in the Tokai area of Japan.

  Masashi Mizuno, Yasuhiko Ito, Akio Tanaka, Yasuhiro Suzuki, Hideki Hiramatsu, Midoriko Watanabe, Yoshikazu Tsuruta, Teppei Matsuoka, Isao Ito, Hiroshi Tamai, [......], Hideaki Shimizu, Hisashi Kurata, Daijo Inaguma, Takeyuki Hiramatsu, Masanobu Horie, Tomohiko Naruse, Shoichi Maruyama, Enyu Imai, Yukio Yuzawa, Seiichi Matsuo
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  ABSTRACT: In Japan, the population of patients on peritoneal dialysis (PD) is <4% of the total number of patients with end-stage renal disease. Few systemic analyses have examined why the number of PD patients has not increased in Japan. We organized a registry to analyze PD patients and retrospectively investigated 561 PD patients (about 5% of all Japanese PD patients) from 13 hospitals in the Tokai area for 3 years from 2005. We investigated background, physical status, laboratory data, status of PD therapy, and the occurrence of PD-related complications, and analyzed reasons for withdrawal from PD. Nutrition did not change significantly during our observation. Urinary volume showed continued decreases after the introduction period. In contrast, PD fluid demand and ultrafiltration volume were significantly increased. For calcium metabolism, multiple phosphate binders were required after the second year of PD therapy. Early drop-out within 3 years after starting PD therapy comprised 50.9% of total withdrawals, with PD-related peritonitis as the most common reason, mainly caused by Gram-positive organisms. Incidence of peritonitis was 42.8 months/patient. Culture-negative results were obtained for 32% of peritonitis cultures. Diabetes affects the prognosis of PD therapy, but not the incidence of peritonitis. We examined clinical status over 3 years in the Tokai area. The results suggest that the incidence of peritonitis needs to be decreased to prevent early withdrawal of PD patients. Education systems to decrease the incidence of peritonitis and techniques to decrease culture-negative results might be important for improving the prognosis of peritonitis.
  Clinical and Experimental Nephrology 06/2011; 15(5):727-37. · 1.37 Impact Factor
• Article: Myoclonus after dextromethorphan administration in peritoneal dialysis.

  Akio Tanaka, Tadashi Nagamatsu, Makoto Yamaguchi, Atsushi Nomura, Fumiko Nagura, Kayaho Maeda, Tatsuhito Tomino, Tatsuhito Watanabe, Hideaki Shimizu, Yoshiro Fujita, Yasuhiko Ito
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  ABSTRACT: To report a case of myoclonus that developed after administration of dextromethorphan. A 64-year-old man was diagnosed with chronic renal failure due to diabetic nephropathy. The patient started on peritoneal dialysis 6 months before he was hospitalized. Two days before hospitalization, he developed cough and sputum and he visited an outpatient clinic, where dextromethorphan was prescribed. After taking a total of 30 mg of dextromethorphan, the patient developed myoclonus, tremor, agitation, slurred speech, and diaphoresis, which continued after he stopped taking the prescribed medicine. He visited an emergency department and was hospitalized for examination and treatment of myoclonus. As the patient's dialysis schedule was adequate, these symptoms were likely not due to uremia. The blood concentration of dextromethorphan (2.68 ng/mL) 60 hours after the 30-mg dose was higher than expected, and the blood concentration of dextrorphan, a metabolite, was lower than expected. We suspected that myoclonus was due to dextromethorphan-related symptoms induced by CYP2D6, which primarily metabolizes dextromethorphan. We analyzed the CYP2D6 gene for polymorphisms and identified CYP2D6 (*)1/(*)10. The patient had been taking metoprolol 40 mg/day for 2 years. The blood concentration of metoprolol 6 hours after administration was 13 ng/mL, which suggests that it was metabolized normally. Metoprolol has another metabolic pathway, via CYP2C19, and this may have led to its lack of accumulation. Moreover, metoprolol may have bound to active CYP2D6. Thus, affinity for CYP2D6, protein-binding rate, and lipid solubility may influence these drug interactions. Total scores for the Adverse Drug Reaction (ADR) probability scale and the Drug Interaction Probability Scale (DIPS) were 9 (highly probable) and 3 (possible), respectively. Myoclonus and other symptoms in this patient may have been caused by a prolonged high concentration of dextromethorphan due to CYP2D6 polymorphisms and drug interactions.
  Annals of Pharmacotherapy 01/2011; 45(1):e1. · 2.13 Impact Factor
• Article: Lymphatic vessels develop during tubulointerstitial fibrosis.

  Izumi Sakamoto, Yasuhiko Ito, Masashi Mizuno, Yasuhiro Suzuki, Akiho Sawai, Akio Tanaka, Shoichi Maruyama, Yoshifumi Takei, Yukio Yuzawa, Seiichi Matsuo
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  ABSTRACT: Recent progress with specific markers of lymphatic vessel endothelium allowed recognition of lymphangiogenic events in various disease states; however, there is little information concerning this process in human chronic renal diseases. To determine this we measured expression of the lymphatic marker D2-40 and vascular endothelial growth factor-C (VEGF-C), a major growth factor in lymphangiogenesis, in 124 human renal biopsy specimens. In the kidneys of control subjects and in uninjured areas of pathologic specimens, lymphatic vessels were detected only around the arcuate and interlobular arteries. An increase in the number of lymphatic vessels was found at the site of tubulointerstitial lesions correlating with the degree of tissue damage and more strongly correlating with areas of fibrosis than inflammation. On serial sections, lymphatic vessel proliferation was found in the tubulointerstitial area at the site of tuft adhesions to Bowman's capsule. Lymphatic growth was associated with VEGF-C expression in inflammatory mononuclear cells and tubular epithelial cells, mainly of proximal tubules. Lymphangiogenesis and VEGF-C expression was elevated in diabetic nephropathy in comparison to other renal diseases. Our results indicate that lymphangiogenesis is a common feature in the progression of the tubulointerstitial fibrosis.
  Kidney International 02/2009; 75(8):828-38. · 6.61 Impact Factor
• Article: Mineralocorticoid receptor blockade ameliorates peritoneal fibrosis in new rat peritonitis model.

  Hayato Nishimura, Yasuhiko Ito, Masashi Mizuno, Akio Tanaka, Yoshiki Morita, Shoichi Maruyama, Yukio Yuzawa, Seiichi Matsuo
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  ABSTRACT: Peritoneal fibrosis (PF) is an important complication of long-term peritoneal dialysis. Although mineralocorticoid and mineralocorticoid receptor (MR) have attracted increasing attention in the field of vascular injury, including the heart, kidney, and vessels, little is known about the role of mineralocorticoid in PF. This work was designed to explore the effects of MR blockade on PF. We developed a new model of PF in rats based on mechanical scraping of the peritoneum. This model is characterized by acute-phase inflammation (neutrophil and macrophage infiltration on days 0-3) and late-phase PF (alpha-smooth muscle actin-positive fibroblast infiltration, type III collagen accumulation, and neoangiogenesis on days 7-14). Peritoneal thickening peaked on day 14. MR was expressed in rat peritoneum and a rat fibroblast cell line. Expression of its effector kinase [serum- and glucocorticoid-induced kinase-1 (Sgk1)], transforming growth factor-beta (TGF-beta), plasminogen activator inhibitor-1 (PAI-1), and CD31-positive vessels increased during the course of PF. Rats were treated with spironolactone, angiotensin receptor blockade (ARB), or angiotensin-converting enzyme inhibitor (ACEI)-ARB-spironolactone starting at 6 h after peritoneal scraping. All parameters, including peritoneal thickening, number of macrophages and CD31-positive vessels, and expression of monocyte chemoattractant protein-1, TGF-beta, PAI-1, and Sgk1, were significantly suppressed by spironolactone (10 mg x kg(-1) x day(-1)). The effects of spironolactone (10 and 20 mg x kg(-1) x day(-1)) were very similar to those of triple blockade. ARB, but not ACEI, significantly reduced peritoneal thickening. Furthermore, peritoneal function assessed by peritoneal equilibration test was significantly improved by spironolactone. Our results suggest that MR is a potential target to prevent inflammation-induced PF in patients on peritoneal dialysis.
  American journal of physiology. Renal physiology 06/2008; 294(5):F1084-93. · 3.68 Impact Factor
• Article: [Safe drug prescribing for patients with renal failure].

  Akio Tanaka, Hideaki Shimizu, Seiichi Matsuo
  Nippon rinsho. Japanese journal of clinical medicine 11/2007; 65 Suppl 8:58-66.
• Article: [Drug-induced nephropathy].

  Hideaki Shimizu, Akio Tanaka, Seiichi Matsuo
  Nippon rinsho. Japanese journal of clinical medicine 11/2007; 65 Suppl 8:549-53.