Dilutant flow characteristics model of coarse particle suspensions with uniform size distribution

Ookawara, Shinichi,Ogawa, Kohei The Korean Society of Rheology 2003 Korea-Australia rheology journal Vol.15 No.1

It is expected that particle size distribution of any portion obtained through screening, is of more uniform than that of the original mixture, typically following such as log-normal, Rosin-Rammler distributions and so on. In this study, therefore, a new relation between parameters of the uniform distribution and flow characteristics of the coarse particle suspensions is derived based on the continuous polydisperse model (Ookawara and Ogawa, 2002b), which is derived from the discrete polydisperse model (Ookawara and Ogawa,2002a). The derived model equation predicts a linear increase of viscosity with shear rate, viz., dilutant flow characteristics. Further, the increase of viscosity is expected to be proportional to the square of volume fraction of particles, and to show the linear dependency on density and average diameter of particles. It is also shown that the uniform distribution model includes additional term that expresses the effect of distribution width. For verification of the model, the experimental results of Clarke (1967) are cited as well as in our previous work for the monodisperse model (Ookawara and Ogawa,2000) since most parameters were varied independently in his work. It is suggested that the newly introduced term expands the applicable range compared with the monodisperse model.

Dilatant flow characteristics model of coarse particle suspensions with uniform size distribution

Shinichi Ookawara 한국유변학회 2003 Korea-Australia rheology journal Vol.15 No.1

Changes in urinary potassium excretion in patients with chronic kidney disease

( Yuichiro Ueda ),( Susumu Ookawara ),( Kiyonori Ito ),( Haruhisa Miyazawa ),( Yoshio Kaku ),( Taro Hoshino ),( Kaoru Tabei ),( Yoshiyuki Morishita ) 대한신장학회 2016 Kidney Research and Clinical Practice Vol.35 No.2

Background: Hyperkalemia is one of the more serious complications of chronic kidney disease (CKD), and the cause of potassium retention is a reduction in urinary potassium excretion. However, few studies have examined the extent of the decrease of urinary potassium excretion in detail with respect to decreased renal function. Methods: Nine hundred eighty-nine patients with CKD (CKD stages G1 and G2 combined: 135; G3a: 107; G3b: 170; G4: 289; and G5: 288) were evaluated retrospectively. Values for urinary potassium excretion were compared between CKD stages, and the associations between urinary potassium excretion and clinical parameters, including diabetes mellitus status and use of renineangiotensinealdosterone system inhibitors, were analyzed using a multivariable linear regression analysis. Results: Urinary potassium excretion gradually decreased with worsening of CKD (G5: 24.8 ± 0.8 mEq/d, P < 0.001 vs. earlier CKD stages). In contrast, the value of fractional excretion of potassium at CKD G5 was significantly higher than that at the other stages (30.63 ± 0.93%, P < 0.001). Multivariable linear regression analysis revealed that urinary potassium excretion was independently associated with urinary sodium excretion (standardized coefficient, 0.499), the estimated glomerular filtration rate (0.281), and serum chloride concentration (e0.086). Conclusion: This study demonstrated that urinary potassium excretion decreased with reductions in renal function. Furthermore, urinary potassium excretion was mainly affected by urinary sodium excretion and estimated glomerular filtration rate in patients with CKD, whereas the presence of diabetes mellitus and use of renineangiotensinealdosterone system inhibitors were not associated with urinary potassium excretion in this study.

Efficacy and safety of adding mizoribine to standard treatment in patients with immunoglobulin A nephropathy: A randomized controlled trial

( Keiji Hirai ),( Susumu Ookawara ),( Taisuke Kitano ),( Haruhisa Miyazawa ),( Kiyonori Ito ),( Yuichirou Ueda ),( Yoshio Kaku ),( Taro Hoshino ),( Honami Mori ),( Izumi Yoshida ),( Kenji Kubota ),( Y 대한신장학회 2017 Kidney Research and Clinical Practice Vol.36 No.2

Background: Mizoribine (MZR) is an immunosuppressive drug used in Japan for treating patients with lupus nephritis and nephrotic syndrome and has been also reportedly effective in patients with immunoglobulin A (IgA) nephropathy. However, to date, few randomized control studies of MZR are performed in patients with IgA nephropathy. Therefore, this prospective, open-label, randomized, controlled trial aimed to investigate the efficacy and safety of adding MZR to standard treatment in these patients, and was conducted between April 1, 2009, and March 31, 2016, as a multicenter study. Methods: Patients were randomly assigned (1:1) to receiving standard treatment plus MZR (MZR group) or standard treatment (control group). MZR was administered orally at a dose of 150 mg once daily for 12 months. Results: Primary outcomes were the percentage reduction in urinary protein excretion from baseline and the rate of patients with hematuria disappearance 36 months after study initiation. Secondary outcomes were the rate of patients with proteinuria disappearance, clinical remission rate, absolute changes in estimated glomerular filtration rate from baseline, and the change in daily dose of prednisolone. Forty-two patients were randomly assigned to MZR (n = 21) and control groups (n = 21). Nine patients in MZR group and 15 patients in the control group completed the study. No significant differences were observed between the two groups with respect to primary and secondary outcomes. Conclusion: The addition of MZR to standard treatment has no beneficial effect on reducing urinary protein excretion and hematuria when treating patients with IgA nephropathy.

Relationship between serum total carbon dioxide concentration and bicarbonate concentration in patients undergoing hemodialysis

( Keiji Hirai ),( Susumu Ookawara ),( Junki Morino ),( Saori Minato ),( Shohei Kaneko ),( Katsunori Yanai ),( Hiroki Ishii ),( Momoko Matsuyama ),( Taisuke Kitano ),( Mitsutoshi Shindo ),( Haruhisa Mi 대한신장학회 2020 Kidney Research and Clinical Practice Vol.39 No.4

Background: Few studies have investigated the relationship between serum total carbon dioxide (CO₂) concentration and bicarbonate ion (HCO₃ ^-) concentration in patients undergoing hemodialysis. We determined the agreement and discrepancy between serum total CO₂ and HCO₃ ^- concentrations and the diagnostic accuracy of serum total CO₂ for the prediction of low (HCO₃ ^- < 24 mEq/L) and high (HCO₃ ^- ≥ 24 mEq/L) bicarbonate concentrations in hemodialysis patients. Methods: One hundred forty-nine arteriovenous blood samples from 84 hemodialysis patients were studied. Multiple linear regression analysis was used to determine factors correlated with HCO₃ ^- concentration. Diagnostic accuracy of serum total CO₂ was evaluated using receiver operating characteristic curve analysis and a 2 × 2 table. Agreement between serum total CO₂ and HCO₃ ^- concentrations was assessed using Bland-Altman analysis. Results: Serum total CO₂ concentration was closely correlated with HCO₃ ^- concentration (β = 0.858, P < 0.001). Area under the curve of serum total CO₂ for the identification of low and high bicarbonate concentrations was 0.989. Use of serum total CO₂ to predict low and high bicarbonate concentrations had a sensitivity of 100%, specificity of 50.0%, positive predictive value of 96.5%, negative predictive value of 100%, and accuracy of 96.6%. Bland-Altman analysis showed moderate agreement between serum total CO₂ and HCO₃ ^- concentrations. Discrepancies between HCO₃ ^- and serum total CO₂ concentrations (serum total CO₂ - HCO₃ ^- ≤ -1) were observed in 89 samples. Conclusion: Serum total CO₂ concentration is closely correlated with HCO₃ ^- concentration in hemodialysis patients. However, there is a non-negligible discrepancy between serum total CO₂ and HCO₃ ^- concentrations.