Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Masahiko Yazawa is active.

Publication


Featured researches published by Masahiko Yazawa.


PLOS ONE | 2016

Early Mortality Was Highly and Strongly Associated with Functional Status in Incident Japanese Hemodialysis Patients: A Cohort Study of the Large National Dialysis Registry

Masahiko Yazawa; Ryo Kido; Seiji Ohira; Takeshi Hasegawa; Norio Hanafusa; Kunitoshi Iseki; Yoshiharu Tsubakihara; Yugo Shibagaki

Background Although dialysis is typically started in an effort to prolong survival, mortality is reportedly high in the first few months. However, it remains unclear whether this is true in Japanese patients who tend to have a better prognosis than other ethnicities, and if health conditions such as functional status (FS) at initiation of dialysis influence prognosis. Methods We investigated the epidemiology of early death and its association with FS using Japanese national registry data in 2007, which included 35,415 patients on incident dialysis and 7,664 with FS data. The main outcome was early death, defined as death within 3 months after initiation of hemodialysis (HD). The main predictor was FS at initiation of HD. Levels of functional disability were categorized as follows: severe (bedridden), moderate (overt difficulties in exerting basic activities of daily living), or mild/none (none or some functional disabilities). Results Early death remained relatively common, especially among elderly patients (overall: 7.1%; those aged ≥80 years: 15.8%). Severely and even only a moderately impaired FS were significantly associated with early death after starting dialysis (adjusted risk ratios: 3.93 and 2.38, respectively). The incidence of early death in those with impaired FS increased with age (36.5% in those with severely impaired FS and aged ≥80 years). Conclusions Early death after starting dialysis was relatively common, especially among the elderly, even in Japanese patients. Further, early death was significantly associated with impaired FS at initiation of HD.


Transplantation proceedings | 2016

Safety of Monitoring Viral and Liver Function Markers in Patients With Prior Resolved Hepatitis B Infection After Kidney Transplantation.

H. Maekawa; Masahiko Yazawa; K. Koitabashi; Naohiko Imai; Hiroo Kawarazaki; Ryuto Nakazawa; Hideo Sasaki; Tatsuya Chikaraishi; Yugo Shibagaki

BACKGROUND Hepatitis B virus (HBV) infection is a risk factor of mortality in kidney transplant recipients. However, information on the risk of HBV reactivation in kidney recipients with prior resolved HBV infection is limited. This study aimed to evaluate the safety of simply monitoring viral and liver markers in living donor kidney transplantation (LDKT) recipients with prior resolved HBV infection. METHODS We retrospectively examined the clinical records of LDKT recipients. Changes in the levels of alanine aminotransferase, aspartate aminotransferase, hepatitis B surface antigen (HBs Ag), surface antibody, core antibody, and HBV-DNA after transplantation were evaluated, and the occurrence of de novo HBV-related hepatitis and allograft function were monitored. RESULTS Of 61 consecutive LDKT patients, seven had prior resolved HBV infection. Four patients underwent ABO-compatible LDKT, whereas two underwent ABO-incompatible LDKT. The median age was 64 years (range, 61-69 years), and two patients were women. The causes of end-stage kidney disease were diabetic nephropathy, hypertensive nephrosclerosis, and chronic glomerulonephritis. Five patients were referred to hepatologists. The history of HBV vaccination was not confirmed in all patients. Prophylaxis with entecavir was administered to two patients with ABO-incompatible LDKT before transplantation. All patients tested negative for HBs Ag and HBV-DNA throughout observation, and none developed de novo HBV-related hepatitis or graft loss. CONCLUSIONS Patients with HBV infection without HBV DNA positivity are eligible for kidney transplants without antiviral therapy, even those on rituximab therapy. Monitoring viral and liver markers combined with hepatologist consultations may ensure safe follow-up in LDKT recipients with prior resolved HBV infection.


Transplantation Proceedings | 2015

Urinary Tract Reconstruction Using Uretero-Ureteral End-To-Side Anastomosis in Kidney Transplant Recipients

Hideo Sasaki; Yuichi Sato; E. Matsuhashi; T. Nishi; S. Hachisuka; Yuichi Katsuoka; Hiroya Kudo; Kazuki Kitajima; M. Yoshioka; Ryuto Nakazawa; Satetsu Miyano; Masahiko Yazawa; Naohiko Imai; Hiroo Kawarazaki; Yugo Shibagaki; Kenjiro Kimura; Tatsuya Chikaraishi

BACKGROUND In kidney transplant recipients, the most widely used method for the reconstruction of the urinary pathway is ureteroneocystostomy, which may be difficult in cases with disused atrophic bladder. In this study, we evaluated kidney transplant recipients who underwent uretero-ureteral end-to-side anastomosis (UUA) in urinary reconstruction due to disused atrophic bladder. METHODS To clarify the effectiveness of this method, we retrospectively reviewed the clinical records of kidney transplant recipients in our hospital. RESULTS A total of 9 recipients with urinary reconstruction using UUA were evaluated. All of these patients had a history of long-term hemodialysis before transplantation, accompanied by complete anuria and small capacity of the bladder. In 4 patients, cranial native ureter was ligated, whereas it was not ligated in the remaining 5 patients. In 2 of 4 patients with cranial ligation, hydronephrosis developed in the native kidney with no further treatment being required. No patients experienced urinary tract complications including hydronephrosis in the graft, urine extravasation, or urinary tract infection in the follow-up period (757.6 ± 491.3 days). Allograft function was maintained well in all patients (serum creatinine level, 1.08 ± 0.23 mg/dL). CONCLUSIONS Although UUA is not a routine method of urinary reconstruction in kidney transplantation, it can be safely performed and should be a surgical option, especially for recipients with disused atrophic bladder. The ligation of cranial native ureter may lead to hydronephrosis of the native kidney, and it is tentatively concluded that UUA without native ureteral ligation is clinically feasible.


Transplantation Proceedings | 2014

Challenges for Preventing the Metabolic Syndrome in Kidney Transplant Recipients, Initial Report: Survey of the Current State of Affairs Before Acting

M. Nakanome; Hideo Sasaki; Masahiko Yazawa; Naohiko Imai; Hiroo Kawarazaki; Yugo Shibagaki; Kenjiro Kimura; Y. Saito; Y. Sakurai; Tatsuya Chikaraishi

OBJECTIVE To prevent the metabolic syndrome preventive in kidney transplant recipients, we measured changes in body composition parameters using bioelectrical impedance analysis (BIA), and measuring renal function, blood tests, quality of life, and consciousness of life improvement. The usefulness of BIA was investigated. SUBJECTS AND METHODS Out of all kidney transplant recipients being treated at an outpatient clinic, 20 (13 males and 7 females) gained ≥ 5 kg after transplantation. We investigated changes after 6 months of physical activity versus initiation. RESULTS After the initiation of body composition parameters using BIA, consciousness of life improvement changed, and measured body composition values and blood data did not worsen. Both systolic and diastolic blood pressures tended to decrease after initiation. CONCLUSIONS Detailed visualization of body composition in addition to the body weight and body mass index, as well as guidance based on the results promoted changes in consciousness, enhanced self-efficacy, and increased motivation for the prevention of the metabolic syndrome, suggesting that BIA is a useful tool in the management of weight gain after kidney transplantation.


Journal of Vascular Access | 2018

Association between post-dialysis hemoglobin level and the survival of vascular access

Hiroki Nishiwaki; Takeshi Hasegawa; Tatsuyoshi Ikenoue; Naoto Tominaga; Masahiko Yazawa; Hiroo Kawarazaki; Yugo Shibagaki; Yosuke Yamamoto; Shingo Fukuma; Shin Yamazaki; Shunichi Fukuhara

Introduction: Although a few dialysis facilities conduct a complete blood cell count for some patients at post-dialysis, including hemoglobin, clinical findings supporting the interpretation of results are scarce. The aim of this study was to investigate the association between post-dialysis hemoglobin level and vascular access failure with clinical data. Methods: Study design: Case crossover design. Setting: Japanese dialysis facilities, which routinely take post-dialysis blood samples, including complete blood cell counts at least once a month. Participants: Hemodialysis patients who experienced vascular access failure in January 2010 until December 2014. Exposure: Post-dialysis hemoglobin level. Main outcome: Vascular access failure treated with endovascular treatment or operation. Statistical analysis: Self-matched odds ratios and 95% confidence intervals were estimated by comparing post-dialysis hemoglobin just before events (“case”) with levels at 6 and 12 months before events (“control”) using conditional logistic regression, and presented with restricted cubic spline. Results: Two hundred and thirty hemodialysis patients with vascular access failure were identified. Mean post-dialysis hemoglobin level before the failure was 11.8 g/dL (standard deviation 1.7). The spline curve showed that higher post-dialysis hemoglobin levels above 11.8 g/dL had a greater odds ratio for vascular access failure. Post-dialysis hemoglobin levels and odds ratios (95% confidence interval) for vascular access failure relative to the reference value (Hb 11.8 g/dL) were Hb 12.0 g/dL, 1.1 (1.0-1.1); Hb 14.0 g/dL, 1.4 (1.0-2.0); and Hb 16.0 g/dL, 2.1 (1.1-4.3). Conclusions: A higher post-dialysis hemoglobin level was associated with vascular access failure. Higher post-dialysis Hb could be a factor that triggers vascular access failure.


Clinical and Experimental Nephrology | 2018

Detection of copy number variations by pair analysis using next-generation sequencing data in inherited kidney diseases

China Nagano; Kandai Nozu; Naoya Morisada; Masahiko Yazawa; Daisuke Ichikawa; Keita Numasawa; Hiroyo Kourakata; Chieko Matsumura; Satoshi Tazoe; Ryojiro Tanaka; Tomohiko Yamamura; Shogo Minamikawa; Tomoko Horinouchi; Keita Nakanishi; Junya Fujimura; Nana Sakakibara; Yoshimi Nozu; Ming Juan Ye; Hiroshi Kaito; Kazumoto Iijima

BackgroundComprehensive genetic approaches for diagnosing inherited kidney diseases using next-generation sequencing (NGS) have recently been established. However, even with these approaches, we are still failing to detect gene defects in some patients who appear to suffer from genetic diseases. One of the reasons for this is the difficulty of detecting copy number variations (CNVs) using our current approaches. For such cases, we can apply methods of array-based comparative genomic hybridization (aCGH) or multiplex ligation and probe amplification (MLPA); however, these are expensive and laborious and also often fail to identify CNVs. Here, we report seven cases with CNVs in various inherited kidney diseases screened by NGS pair analysis.MethodsTargeted sequencing analysis for causative genes was conducted for cases with suspected inherited kidney diseases, for some of which a definitive genetic diagnosis had not been achieved. We conducted pair analysis using NGS data for those cases. When CNVs were detected by pair analysis, they were confirmed by aCGH and/or MLPA.ResultsIn seven cases, CNVs in various causative genes of inherited kidney diseases were detected by pair analysis. With aCGH and/or MLPA, pathogenic CNV variants were confirmed: COL4A5 or HNF1B in two cases each, and EYA1, CLCNKB, or PAX2 in one each.ConclusionWe presented seven cases with CNVs in various genes that were screened by pair analysis. The NGS-based CNV detection method is useful for comprehensive screening of CNVs, and our results revealed that, for a certain proportion of cases, CNV analysis is necessary for accurate genetic diagnosis.


Therapeutic Apheresis and Dialysis | 2017

Association Between Staphylococcus aureus Bacteremia and Hospital Mortality in Hemodialysis Patients With Bloodstream Infection: A Multicenter Cohort From Japanese Tertiary Care Centers

Takahiro Imaizumi; Takeshi Hasegawa; Atsushi Nomura; Sho Sasaki; Hiroki Nishiwaki; Takaya Ozeki; Hideaki Shimizu; Shun Minatoguchi; Taishi Yamakawa; Masahiko Yazawa; Daisuke Uchida; Hiroo Kawarazaki; Masahito Miyamoto; Tomo Suzuki; Kenichiro Koitabashi; Masahide Furusho; Yoshiro Fujita

Multiple studies have shown that Staphylococcus aureus bacteremia (SAB) has been a major cause of death in hemodialysis patients. We examined whether SAB is a risk for mortality among chronic hemodialysis patients in Japan where the standard vascular access is arteriovenous fistula (AVF). This was a multicenter, retrospective study of maintenance hemodialysis patients with bloodstream infection (BSI) from 2011 to 2013 at tertiary care centers in Japan. The endpoint was hospital mortality. Our cohort contained 32 SAB cases (14 MRSA and 18 MSSA) and 42 non‐SAB cases. Hospital mortality was higher among SAB cases than non‐SAB cases (46.9% vs. 23.8%, P = 0.038). In patients with BSI, SAB was significantly associated with hospital mortality after adjustment for potential confounders, including type of vascular access (OR 3.26). S. aureus was the leading cause of BSI and hospital mortality among this cohort. Therefore, initial empiric treatment should cover for S. aureus.


Nephrology | 2014

Asymptomatic post-transplant lymphoproliferative disorder diagnosed at one year protocol renal allograft biopsy.

Kazuki Kitajima; Hideo Sasaki; Junki Koike; Ryuto Nakazawa; Yuichi Sato; Masahiko Yazawa; Kayo Tsuruoka; Hiroo Kawarazaki; Naohiko Imai; Sayuri Shirai; Yugo Shibagaki; Tatsuya Chikaraishi

Post‐transplant lymphoproliferative disorder (PTLD) is a neoplastic complication with a potentially fatal outcome that develops as a consequence of immunosuppression, and is mainly associated with Epstein‐Barr virus (EBV) infection. A 70‐year‐old woman underwent a live unrelated, ABO‐incompatible renal transplant for end‐stage renal disease. One year after transplantation, protocol biopsy revealed pathological changes indicative of the histological subtype of ‘early lesions of PTLD’ according to the World Health Organization classification, while the patient showed no clinical signs or symptoms. The patient was finally diagnosed with EBV‐positive PTLD by in situ hybridization for EBER (EBV‐encoded RNA), and was successfully treated based on the reduction of immunosuppression. Protocol biopsy within the first post‐transplant year is the only diagnostic measure to detect asymptomatic early PTLD, which allows for early intervention and leads to better outcomes.


Journal of Artificial Organs | 2010

Brachial-brachial autogenous arteriovenous fistula in a dialysis patient with Staphylococcus aureus bacteremia.

Yuichi Sato; Masahito Miyamoto; Masahiko Yazawa; Ryuto Nakazawa; Hideo Sasaki; Satetsu Miyano; Hisashi Tsutsumi; Kenjiro Kimura; Tatsuya Chikaraishi

As the number of patients on hemodialysis increases, there will also be an increase in the number of patients with inadequate superficial veins for the creation of an autogenous arteriovenous fistula (AVF). In those patients, medical devices such as vascular prostheses or tunneled-cuffed catheters are necessary to maintain dialysis access. However, these devices are frequently associated with bacterial infection. We recently encountered a dialysis patient who underwent tunneled-cuffed catheter insertion because of the lack of usable superficial veins for autogenous access, and this patient subsequently developed catheter-related Staphylococcus aureus bacteremia with multiple metastatic infections. Despite immediate removal of the catheter, the infection persisted over an extended period, which was a condition precluding the further use of catheters or other prosthetic materials. To handle this situation, we utilized the deep brachial vein to construct an autogenous AVF. After ligating numerous branches, the vein was anastomosed to the brachial artery and then transposed to the subcutaneous space. The newly constructed autogenous AVF, which successfully kept the patient free from foreign materials, greatly contributed to the relief of persistent infection. Although the brachial vein is rarely used for AVF creation, we suggest that it can serve as an option to create an alternative AVF in a patient with inadequate superficial veins.


Internal Medicine | 2019

Tubulointerstitial Nephritis Associated with Enteritis and Sacroiliitis

Shu Ushimaru; Daisuke Ichikawa; Masahiko Yazawa; Tomo Suzuki; Eri Okada; Junki Koike; Yugo Shibagaki

The association between sacroiliitis and tubulointerstitial nephritis has not been reported. A 28-year-old man with a history of clinically diagnosed ulcerative colitis (4 years earlier) and sacroiliitis (6 months earlier) developed renal dysfunction 9 months ago, which progressed thereafter. We diagnosed him with tubulointerstitial nephritis by a renal biopsy, for which we started steroid therapy. Subsequently, his renal dysfunction, sacroiliitis, and enteritis partially improved. A pathological analysis of the kidney and intestine revealed lymphocyte infiltration and non-caseating granuloma in both organs. The similarities in the pathological findings and treatment response suggested a pathogenetic association between tubulointerstitial nephritis, enteritis, and sacroiliitis.

Collaboration


Dive into the Masahiko Yazawa's collaboration.

Top Co-Authors

Avatar

Yugo Shibagaki

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Hideo Sasaki

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Tatsuya Chikaraishi

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Ryuto Nakazawa

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Kenjiro Kimura

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Naohiko Imai

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Hiroya Kudo

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Kazuki Kitajima

St. Marianna University School of Medicine

View shared research outputs
Top Co-Authors

Avatar

Daisuke Ichikawa

St. Marianna University School of Medicine

View shared research outputs
Researchain Logo
Decentralizing Knowledge