T Yokoyama

Tokyo Medical University, Edo, Tōkyō, Japan

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Publications (13)18.46 Total impact

  • H Iwamoto · Y Nakamura · O Konno · K Hama · T Yokoyama · Y Kihara · S Kawachi · M Shimazu ·
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    ABSTRACT: Posttransplant anemia (PTA) influences kidney graft function and prognosis; however, there is no consensus regarding target hemoglobin (Hb) levels. We examined several cases of PTA to identify any correlation between Hb levels and graft function. We evaluated 84 kidney transplant recipients (50 men and 34 women; mean age, 46.7 years) who were treated at our department between February 2004 and March 2012 and were available for a 2-year post-transplant follow-up. Hb levels and serum creatinine levels before transplantation and at 1, 3, 6, 12, and 24 months after transplantation were compared. We examined the correlation between the degree of anemia and renal function among the patients. Data were analyzed using Spearman's rank correlation coefficient and Friedman tests. The mean pretransplantation Hb level was 10.4 g/dL, whereas Hb levels at 6, 12, and 24 months after transplantation were significantly increased to 11.6, 12.2, and 12.4 g/dL, respectively, suggesting an improvement in anemia after the transplantation. Correlation analysis between anemia and kidney graft dysfunction revealed significant correlations at 1, 3, 12, and 24 months after transplantation. Subjects were stratified for correlation analysis according to Hb level at 24 months after transplantation: <10, 10-10.9, 11.0-11.9, 12.0-12.9, and ≥13.0 g/dL. A significant improvement in kidney graft function was noted in patients with an Hb level ≥11 g/dL at 2 years after transplantation. Anemia improved significantly by 3 months after transplantation. A significant correlation between PTA and kidney graft function was apparent, and the prognosis for kidney graft function was poor in patients with Hb levels ≤11 g/dL.
    Transplantation Proceedings 03/2014; 46(2):496-8. DOI:10.1016/j.transproceed.2013.12.043 · 0.98 Impact Factor
  • T. Yokoyama · O. Konno · Y. Nakamura · Y. Kihara · H. Iwamoto · M. Shimazu ·
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    ABSTRACT: Background In this retrospective study, we analyzed histologic changes identified through protocol biopsy (PB) at 1 year after kidney transplantation (KT). We focused on the pathologic changes observed in patients with a history of treatment for graft rejection within 1 year of transplantation. Methods Between January 2008 and December 2011, 56 patients underwent KT at our center. We assessed the histologic findings observed at 1 year after renal transplantation using the Banff 2007 classification. At our center, PBs are performed immediately after or at 1 hour after transplantation, and at 1 year after KT. PBs were performed in 39 patients; PBs could not be performed in 17 patients because of various causes. Of the 39 patients, 29 stabilized without clinical rejection and without treatment (the NTx group); 10 patients showed pathologic changes or clinical rejection after steroid pulse therapy within 1 year (the Tx group). We compared these 2 groups with respect to baseline data, renal function, and pathologic scores. Results The interstitial fibrosis (“ci”) score, according to the Banff classification, was significantly greater in the NTx group (0.89) than in the Tx group (0.50) at 1 year after transplantation. Conclusions The currently applied early steroid withdrawal regimen may be not be ideal for preventing pathologic changes occurring after KT. In addition to the PB performed 1 year after KT, PB should be performed within 1 year of renal transplantation to identify early signs of rejection and to provide access to appropriate treatment regimes.
    Transplantation Proceedings 03/2014; 46(2):349–352. DOI:10.1016/j.transproceed.2013.12.010 · 0.98 Impact Factor

  • Transplantation 11/2012; 94(10S):601. DOI:10.1097/00007890-201211271-01161 · 3.83 Impact Factor
  • Y. Nakamura · O. Konno · T. Yokoyama · Y. Kihara · K. Hama · H. Iwamoto · M. Shimadu ·

    Transplantation 11/2012; 94(10S):598. DOI:10.1097/00007890-201211271-01154 · 3.83 Impact Factor
  • T Yokoyama · O Konno · Y Nakamura · Y Kihara · Y Jojima · K Hama · H Iwamoto · M Shimazu · M Otani ·
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    ABSTRACT: Advancements in immunosuppressive therapy have enabled control of early acute rejection and improved long-term kidney transplantation (KT) survival. Chronic histopathologic changes influence graft survival rate. We examined tubulointerstitial changes at 1 year after KT, focusing on the progression of interstitial fibrosis and/or tubular atrophy (IF/TA). Using the Banff' 07 classification, we assessed the histological findings obtained at 1 year after transplantation of 38 patients who underwent the procedure between January 2008, and March 2010. In 24 cases, we obtained scores for interstitial fibrosis (ci) >1 and/or tubular atrophy (ct) > 1. We classified the patients into two groups, namely, less than borderline changes (BCs) (t0, i0, or i1; group A) versus BCs and above (t > 1, i2, or i3; group B). We compared their baseline data, renal function, and pathological scores. The mean serum creatinine levels were 1.06 mg/dL for group A and 1.32 mg/dL for group B. The "ct" grading according to the Banff' 07 classification was 0.83 for group A and 1.50 for group B (both P < .05). No significant difference was observed with respect to the percentage of patients with IF/TA (Banff category 5). Patients more within 1 year after KT with BCs who show irreversible tubular atrophy by biopsy experience impaired renal function. The presence of BC at the first year may not be associated with IF/TA.
    Transplantation Proceedings 04/2012; 44(3):607-9. DOI:10.1016/j.transproceed.2011.11.044 · 0.98 Impact Factor
  • Y Nakamura · K Hama · H Iwamoto · T Yokoyama · Y Kihara · O Konno · Y Jojima · M Shimazu ·
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    ABSTRACT: The early results of liver transplantations (OLT) in patients with advanced hepatocellular carcinoma (HCC) were poor because of frequent tumor recurrence. However, OLT has significant, theoretical advantage that it removes both the tumor and the organ that is at a risk of malignancy. The Japanese law on organ transplantation limited the availability of cadaveric liver donors until its revision on July 17, 2011. ABO-incompatible OLT was formerly contraindicated because performed anti-A/B antibodies on recipient endothelial cells raised the risk of antibody-mediated humoral graft rejection. We have herein described four successful cases of steroid withdrawal among adult patients who underwent living donor OLT from ABO-incompatible donors. In addition, we transplanted a liver from a living donor into an ABO-incompatible recipient on August 9, 2004. The 55-year-old man with HCC due to hepatitis B virus (HBV) a cirrhosis had a Child-Pugh score of C, and Model for End-stage Liver Disease score of 22. Two tumors greater than 5 cm, exceeded the Milan criteria. His des-gamma-carboxy prothrombin level was 6 mAu/mL, and alpha-fetoprotein, 18.78 ng/mL. Antirejection therapy included multiple perioperative plasmaphereses and splenectomy; with an immunosuppressive regimen consisting of tacrolimus, methylprednisolone, and mycophenolate mofetil. The maintenance dose of immunosuppression did not differ from that of ABO-identical cases. After transplantation, we used intrahepatic arterial infusion therapy with prostaglandin E1 (PG E1). The patient had complications of portal vein thrombosis, hepatic artery thrombosis, and acute myocardial infarction, which were treated by interventional radiology in the posttransplantation period. We controlled the HBsAb titer by administering hepatitis B immunoglobulin and lamivudine (200 IU/L doses) for 1 year after OLT and 100 IU/L doses thereafter. As a result, the patient achieved long-term, disease-free graft survival without steroids. He currently has good liver function and leads a normal lifestyle. Our results suggested the feasibility of controlling antibody-mediated humoral rejection and other complications in living donor liver transplantations into ABO-incompatible adults via intrahepatic arterial PG E1 infusion splenectomy, and plasmapheresis with regular immunosuppression. Withdrawal of steroids, HBV vaccination, and lamivudine, an nucleoside analog reverse transcriptase inhibitor, have achieved long-term (7 years) survival without recurrent HBV infection or tumor.
    Transplantation Proceedings 03/2012; 44(2):565-9. DOI:10.1016/j.transproceed.2012.01.029 · 0.98 Impact Factor
  • H Iwamoto · K Hama · O Konno · T Yokoyama · Y Kihara · Y Jojima · Y Nakamura · H Takeuchi · M Shimazu ·
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    ABSTRACT: Beneficial effects of protocols using minimal steroid exposure have been recently reported. The purpose of this study was to evaluate the outcomes of kidney transplantation recipients who received immunosuppression protocols with early steroid withdrawal (ESW) at our center. We retrospectively studied 84 kidney transplant recipients who had received ESW immunosuppressive protocols at our center from March 2005 to December 2010. The immunosuppressive regimen was a combination of calcineurin inhibitors (tacrolimus/cyclosporine), methylprednisolone, which was tapered and discontinued within 2 months, mycophenolate mofetil, and basiliximab (postoperative days 0 and 4). We compared the outcomes of our ESW recipients with those of a historical control group (February 2003 to January 2005; n = 18). Clinical acute rejection episodes were observed in 15 (17.9%) and 5 (27.8%) cases in the ESW and control groups, respectively. Cytomegalovirus infection occurred in 12 (14.3%) and 5 (27.8%) cases in the ESW and control groups, respectively. The creatinine levels at 1 year after transplantation were 1.3 ± 0.4 mg/dL and 1.3 ± 0.5 mg/dL in the ESW and control groups, respectively. In the ESW group of 84 recipients, actuarial patient survival at 1 year was 94.0%. In the historical group of 18 recipients, the actuarial patient survival at 1 year was 100% (P = .76). In the ESW group the graft survival rate at 1 year was 95.2%. In the historical group, graft survival rate at 1 year was 100% (P = .65). There were no significant differences in the parameters between the groups. The outcomes from this study were considered to be acceptable; however, the possibility of improving the protocols exists.
    Transplantation Proceedings 01/2012; 44(1):179-81. DOI:10.1016/j.transproceed.2011.12.068 · 0.98 Impact Factor
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    ABSTRACT: Graceptor is a new modified-release once-daily formulation of tacrolimus with an efficacy and safety profile similar to twice-daily tacrolimus (Prograf), as identified by clinical trials, offering a more convenient dosing regimen to improve adherence. The aim of this study was to analyze the safety of a 1:1 dose conversion from twice-daily Prograf to once-daily Graceptor in stable kidney transplant recipients. We switched 33 Japanese patients who had undergone kidney transplantation ≥1 years before from twice-daily Prograf to once-daily Graceptor. The dose conversion ratio between Prograf and Graceptor was 1:1. We compared the following parameters: minimum tacrolimus concentration (C(min)); concentration dose per weight (CDW); serum creatinine (sCr); blood urea nitrogen (BUN); total cholesterol (TC); high-density lipoprotein cholesterol (HDL-C); uric acid (UA); fasting blood sugar (FBS). Time points for measurements were 1 month before study start and 1 and 2 months afterward. The mean age of the subjects in this study was 46.5 ± 13.1 years. Mean C(min) decreased from 4.55 ± 1.79 to 3.20 ± 1.22 ng/dL. The mean CDW also decreased, from 99.8 ± 69.5 to 75.0 ± 55.1 mg/dL/kg over the 2 months. There were no significant changes in sCR, BUN, UA, and FBS. Mean TC increased from 187.5 ± 51.4 to 194.3 ± 43.4 mg/dL, and mean HDL-C changed from 53.7 ± 12.0 to 56.1 ± 11 mg/dL. There were no episodes of rejection or infection. We conclude that switching from Prograf to Graceptor is safe and has the advantage of improving adherence. It could also have a beneficial effect in controlling glycemic levels and the adverse effects of tacrolimus. In many cases (25%-30%), the minimum concentration of tacrolimus decreased after changing tablets. With Graceptor, the ratio of area under trough level to area under the curve (AUC) is low compared with Prograf, resulting in low C(min) values of 1-2 ng/mL, and the AUC for Graceptor is very similar to that for Prograf.
    Transplantation Proceedings 01/2012; 44(1):124-7. DOI:10.1016/j.transproceed.2011.11.051 · 0.98 Impact Factor
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    ABSTRACT: This report presents a falsely abnormally elevated blood trough concentration (C(t)) of tacrolimus measured by antibody-conjugated magnetic immunoassay (ACMIA) methods in a renal transplant recipient. Because the C(t) of tacrolimus was 78.5 ng/mL at day 2 after a 52-year-old man underwent renal transplantation, we stopped the tacrolimus extended-release formulation. However, because the abnormally elevated blood C(t) continued in the range of 41.1-59.1 ng/mL, we then measured the tacrolimus concentration in a stored blood sample before renal transplantation, it was 43 ng/mL. Consequently, the day-7 blood sample was measured with both ACMIA and enzyme-linked immunoassay, showing C(t) values of 42.8 ng/mL and 0.89 ng/mL, respectively. Because the abnormally elevated C(t) was falsely measured by the ACMIA method, we restarted tacrolimus However, the calcineurin inhibitor was subsequently converted to cyclosporine at day 21 after renal transplantation. Although cyclosporine was also measured by ACMIA, there was not an abnormally elevated C(t). Subsequently, the tacrolimus concentration ratio in plasma and whole blood (P/B-tacrolimus concentration ratio) was measured by ACMIA in a posttacrolimus blood sample. The P/B-tacrolimus concentration ratio was 100%. In contrast, the P/B-tacrolimus concentration ratio was <30% in 2 control patients administered tacrolimus. It has been reported recently that there were cases showing falsely slightly elevated C(t) of tacrolimus within the therapeutic range of concentrations. Therefore, we must be careful not to reduce the tacrolimus dose falsely. We consider confirmatory methods for a falsely abnormally elevated C(t) of tacrolimus measured by ACMIA to (1) measure P/B-tacrolimus concentration ratio, (2) compare ACMIA with another measurement, and (3) evaluate a blood sample stored before tacrolimus administration.
    Transplantation Proceedings 01/2012; 44(1):134-6. DOI:10.1016/j.transproceed.2011.11.043 · 0.98 Impact Factor
  • H Iwamoto · K Hama · Y Nakamura · K Osamu · T Yokoyama · Y Kihara · T Ashizawa · T Niido · N Matsuno · T Nagao ·
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    ABSTRACT: The incidence of biliary complications after adult living donor liver transplantation (ALDLT) are still high even though various devices have been reported to overcome them. From October 2000 to April 2007, we performed 52 ALDLTs which included 15 ABO-incompatible grafts. Median follow-up was 565 days. In 49 procedures, we used duct-to-duct anastmosis with a stent inserted in the recipient duct and out through the common bile duct wall as an external stent, and in 3 procedures, we used duct-to-jejunostomy anastomosis. We investigated postoperative biliary complications and their management. Forty-four patients received right lobe grafts and 8 received left lobe grafts. Among patients in whom duct-to-duct anastomosis was used, nine (20.5%) developed biliary complications including bile leakage in five and biliary strictures in four. All bile leakage was treated with reoperation. Three biliary strictures were treated with stent placement, and one biliary stricture was treated with magnetic compression anastomosis. Among the three patients in whom duct-to-jejunostomy was used, two (66.7%) had bile leakage and stricture, respectively. Two of four ABO-incompatible patients (50%) had hepatic artery thrombosis with biliary complications, a high incidence. In our series of ABO-incompatible patients undergoing ALDLT, those who developed hepatic artery thrombosis exhibited a high incidence of biliary complications.
    Transplantation Proceedings 11/2008; 40(8):2539-41. DOI:10.1016/j.transproceed.2008.07.042 · 0.98 Impact Factor
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    ABSTRACT: In Japan, living donor renal transplantation has gained momentum due to an increased number of patients with end-stage renal disease. Living donation not only provides better outcomes, but also the recipients usually need less medications, thereby increasing the quality of life and reducing the potential side effects of immunosuppression. For the past 25 years, our center had performed 140 open donor nephrectomy (OPNx) renal transplantations. Since July 2003, we changed our procurement operation to living hand-assisted laparoscopic donor nephrectomy (HALNx) in 49 cases. Our operative technique consisted of two 12-mm ports placed in the midaxillary line at the superior and inferior levels of the umbilicus. Next, a 5-cm incision was made in the midline periumbilicus and the hand port system fitted through a midline abdominal incision. In 49 cases, HALNx was completed successfully; no patient required conversion to laparotomy. The estimated blood loss was 33.0 +/- 43.4 g and no patient required blood transfusion. In comparison, in OPNx the blood loss was 426.5 +/- 247.6 g (P < .001). The mean operative times were 167.4 +/- 39.7 minutes for HALNx and 228.4 +/- 35.7 minutes for OPNx (P < .001). The postoperative hospital stays were 9.1 +/- 3.8 days for HALNx and 13.0 +/- 1.9 days for OPNx (P < .001). For 3 years prior to introduction of HALNx, we had performed only 10 living donor renal transplantations. Since the introduction of HALNx in 2003, the number of living donors has tripled during the following 3 years. Herein we have reported that HALNx was superior in terms of less operative time and blood loss, postoperative pain and recovery, and shorter hospital stay. Overall donor patient satisfaction was also better in the HALNx group. HALNx is a safe procedure that makes kidney donation more appealing to potential live donors and has increased the living donor pool at our center.
    Transplantation Proceedings 10/2008; 40(7):2104-7. DOI:10.1016/j.transproceed.2008.07.081 · 0.98 Impact Factor
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    ABSTRACT: Although living donor liver transplantation (LDLT) was established as a treatment for end-stage liver disease in Japan, the indication for LDLT across an ABO-incompatible barrier remains controversial. The purpose of this study was to elucidate the role of plasmapheresis in incompatible LDLT. Eleven adult patients (seven men and four women) who underwent incompatible LDLT were enrolled in this study. Of these three patients had hepatocellular carcinoma, three chronic hepatitis C, one Wilson's disease, one autoimmune hepatitis, one chronic hepatitis B, one hemochromatosis, and one fulminant hepatic failure. The immunosuppressive regimen consisted of tacrolimus, prednisolone, mycophenolate mofetil (or cyclophosphamide), and prostaglandin E1 in all patients. Multiple plasmapheresis was performed perioperatively to reduce the recipient's antibody titers against the donor's blood type. Plasmapheresis was useful for the reduction of the recipient's antibody titers to x 16 or lower before and after transplantation. There was no difference in transplant outcome between the 11 patients with incompatible blood group and 30 patients with identical or compatible blood groups. Major postoperative complications such as intrahepatic biliary complications and hepatic necrosis may occur in incompatible transplantation. Several investigators suggested that anti-immunoglobulin (Ig) M and anti-IgG antibody titers sustained these complications. The antibody titers must be decreased sufficiently with plasmapheresis. An elevation of anti-ABO titers after transplantation may be a predictive risk factor for increased mortality and morbidity. In order to perform LDLT in a safer manner, plasmapheresis is an indispensable treatment to improve the outcome of ABO-incompatible cases.
    Transplantation Proceedings 01/2007; 38(10):3629-32. DOI:10.1016/j.transproceed.2006.10.122 · 0.98 Impact Factor
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    ABSTRACT: In Japan ABO-incompatible liver transplantation has been done on >100 occasions up to 2003. However, <30% are cases involving adults. The difficultly of ABO-incompatible liver transplantation is associated with the high frequency of humoral rejection and local disseminated intravascular coagulation (DIC), leading to many postoperative complications. We report a successful case of adult ABO-incompatible liver transplantation with the use of an intrahepatic artery infusion. A 36-year-old man with Wilson disease, underwent living donor liver transplantation from an ABO-incompatible donor. The immunosuppressive therapy included multiple perioperative plasmaphereses, splenectomy, and treatment with tacrolimus, methylprednisolone, and cyclophosphamide. The dose and blood level of tacrolimus were the same as in ABO-compatible cases. In addition to these therapies, we administered an intrahepatic arterial infusion with prostaglandin (PG) E1 alone. After perioperative plasmapheresis and cyclophosphamide, antidonor blood group antibody titers remained undiluted and without vascular complications throughout the postoperative course, but there was a tendency for bleeding that continued for 10 days after transplantation. On postoperative day 10, a reexploration was performed for intraabdominal bleeding. During another operation on postoperative day 59 a biloma was found and drained. The patient has now survived for 120 days after transplantation with normal liver function. Beneficial effect of intrahepatic artery infusion with PGE1 seems to be useful in adult ABO-incompatible liver transplantation.
    Transplantation Proceedings 10/2004; 36(8):2269-73. DOI:10.1016/j.transproceed.2004.08.094 · 0.98 Impact Factor