Arteriovenous graft patency outcomes and prognostic factors.

OBJECTIVES: Arteriovenous graft for hemodialysis shows poorer outcomes than arteriovenous fistula, due to frequent stenosis and thrombosis. We investigated arteriovenous graft patency outcomes and prognostic factors for these outcomes. METHODS: We included a single-center cohort of patients receiving arteriovenous graft for hemodialysis access from 2010 to 2014. Demographics, laboratory data, comorbidities, and medications were collected from medical records. Surgical factors related to graft operation including the type and diameter of connected vessels, graft location, and type of operation (elective or emergency) were also recorded. Outcomes included primary and secondary patency. Survival analysis was conducted using the Kaplan-Meier method; univariate and multivariate analyses were used to evaluate the prognostic factors. RESULTS: Data from 225 grafts were analyzed. During the follow-up period (mean: 583 days, range: 1-1717 days), 138 (61%) grafts required intervention and 46 (20%) permanently failed. Primary patency at one, two, and three years was 42%, 20%, and 16%, respectively. Secondary patency at one, two, and three years was 85%, 72%, and 64%, respectively. Multivariate analysis showed that primary patency was negatively associated with increasing age and location of vessel anastomosis (reference-brachiobrachial anastomosis; brachiobasilic - HR, 0.569; 95% CI, 0.376-0.860; p = 0.007; brachioaxillary anastomosis - HR 0.407; 95% CI, 0.263-0.631; p < 0.0001); secondary patency was positively associated with diastolic blood pressure, serum albumin level, and hemoglobin over 10 g/dL. Adverse events other than stenosis or thrombosis, such as infection/inflammation or pseudoaneurysm were observed in approximately 20% of grafts. CONCLUSIONS: Factors associated with diminished primary arteriovenous graft patency included increased patient age and location of vessel anastomosis (brachiobrachial type compared to brachiobasilic or brachioaxillary type); diminished secondary patency was associated with low diastolic blood pressure, low serum albumin, and hemoglobin level under 10 g/dL. Among these factors, diastolic blood pressure, serum albumin, and hemoglobin level may be modifiable and could improve arteriovenous graft patency outcomes.

Ten-year observational follow-up of a randomized trial comparing cyclosporine and tacrolimus therapy combined with steroid withdrawal in living-donor renal transplantation.

Although various strategies for steroid withdrawal after transplantation have been attempted, there are few reports of the long-term results of steroid withdrawal regimens in kidney transplantation. Earlier, we reported on a 5-year prospective, randomized, single-center trial comparing the safety and efficacy of cyclosporine (CsA) plus mycophenolate mofetil (MMF) with that of tacrolimus (TAC) plus MMF, when steroids were withdrawn 6 months after kidney transplantation in low-risk patients. We now report the 10-year observational data on the study population. We collected data from the database of the Organ Transplantation Center, Samsung Medical Center for 5 years after completion of the original study (TAC group n = 62; CsA group n = 55). The 10-year patient survival, death-censored graft survival, and acute rejection-free survival did not differ between groups (98% vs 96%; P = 0.49, 78% vs 85%; P = 0.75 and 84% vs 76%; P = 0.14 in the TAC group vs CsA group, respectively). In low-risk patients, there was no difference in long-term patient and graft survival between TAC- and CsA-based late steroid withdrawal regimens that included MMF treatment. More long-term randomized clinical trials are needed to clarify the benefits of late steroid withdrawal in kidney transplantation.

Tissue expression of tubular injury markers is associated with renal function decline in diabetic nephropathy.

AIMS: The pathogenesis of diabetic kidney disease (DKD) is complex and multifactorial; increasing evidence suggests that tubular injury and inflammatory process are involved in disease progression. We investigated the potential association of renal expression of tubular injury markers, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and inflammatory markers, tumor necrosis factor receptor (TNFR) 1 and 2 with renal progression in pathologically proven diabetic nephropathy (DN). METHODS: We identified 122 patients with confirmed DN. After excluding patients with other coexisting renal disease or estimated glomerular filtration rate (eGFR) <30mL/min/1.73m2, 35 patients were included. Annual decline of (GFR decline slope) was calculated using linear regression analysis. Tissue tubular and glomerular expressions of NGAL, KIM-1, TNFR1, and TNFR2 were assessed using immunohistochemistry. RESULTS: Median baseline urinary protein to creatinine ratio (uPCR) was 6.76 (2.18-7.61) mg/mg Cr, median baseline eGFR was 50 (43-66) mL/min per 1.73m2, and median GFR decline slope was 15.6 (4.4-35.1) mL/min per 1.73m2 per year. Positive correlations were observed between tubular expressions of NGAL and KIM-1, and GFR decline slopes (r=0.601, p<0.001; r=0.516, p=0.001, respectively), and between tubular expressions of KIM-1 and uPCR (r=0.596, p<0.001), and between NGAL and interstitial fibrosis and tubular atrophy (IFTA) score (r=0.391, p=0.024). No correlations were found between glomerular or tubular expressions of TNFRs, and clinical parameters including GFR decline slopes. On multivariate analysis, the association between tubular expressions of KIM-1 and GFR decline slopes was dependent on uPCR. Tubular expressions of NGAL were independently associated with GFR decline slopes, with an adjusted coefficient factor of 0.290 (95% confidence interval, 0.009-0.202, p=0.038). CONCLUSIONS: These findings suggest that tubular injury plays a key role in the pathogenesis of DKD in high-risk patients. Further studies are warranted to determine whether tubular injury could be a therapeutic target in DKD.

Effect of prolonged racing on muscle activity and spatiotemporal variables: double-poling technique.

[Purpose] The purpose of this study was to examine the effect of a 40-minute race on muscle activity and spatiotemporal cycle variables at four-time points during a 12-km roller skiing test using the double-poling technique. [Subjects and Methods] Five elite cross-country (XC) skiers on the Korean National reserve team participated in the study. Part of a biathlon course that consisted of both flat land and slopes was selected, and three measurements were recorded after every 4-km lap. Spatiotemporal variables, mean frequency and mean amplitude of 6 muscles were the chosen computational parameters. [Results] Significant differences were observed in cycle time and rate. The mean frequency of the upper-body muscles exhibited declining trends, with statistically significant differences for the triceps brachii. In addition, there were significant differences in the mean amplitude of the tibialis anterior and gastrocnemius. The activity of the triceps brachii, tibialis anterior, and gastrocnemius showed some degree of dependence on the technique. [Conclusion] Training and race strategies that improve the function of elbow extensors and ankle dorsiflexors are important in XC skiing; the application of roller-ski training research to actual XC skiing competitions is needed.

Effect of ski simulator training on kinematic and muscle activation of the lower extremities.

[Purpose] This study aimed to verify the effectiveness of an augmented reality-based ski simulator through analyzing the changes in movement patterns as well as the engagement of major muscles of the lower body. [Subjects] Seven subjects participated in the study. All were national team-level athletes studying at "K" Sports University in Korea who exhibited comparable performance levels and had no record of injuries in the preceding 6 months (Age 23.4 ± 3.8 years; Height 172.6 ± 12.1 cm; Weight 72.3 ± 16.2 kg; Experience 12.3 ± 4.8 years). [Methods] A reality-based ski simulator developed by a Korean manufacturer was used for the study. Three digital video cameras and a wireless electromyography system were used to perform 3-dimensional motion analysis and measure muscle activation level. [Results] Left hip angulation was found to increase as the frequency of the turns increased. Electromyography data revealed that the activation level of the quadriceps group's extension muscles and the biceps femoris group's flexing muscles had a crossing pattern. [Conclusion] Sustained training using an augmented reality-based ski simulator resulted in movements that extended the lower body joints, which is thought to contribute to increasing muscle fatigue.