Impact Response of Hammerhead Pier Fibrous Concrete Beams Designed with Topology Optimization

Reducing the weight of concrete beams is a primary (beyond strength and durability) concern of engineers. Therefore, this research was directed to investigate the impact response of hammerhead pier concrete beams designed with density-based method topology optimization. The finite element topology optimization was conducted using Autodesk fusion 360 considering three different mesh sizes of 7 mm, 10 mm, and adaptive meshing. Three optimized hammerhead beam configurations; HB1, HB2, and HB3, respectively, with volume reductions greater than 50 %. In the experimental part of this research, nine beams were cast with identical size and configuration to the optimized beams. Three beams, identical to the optimized beams, were tested under static bending for verification purposes. In comparison, six more beams, as in the preceding three beams but without and with hooked end steel fibers, were tested under repeated impact load. The test results revealed that the highest flexural capacity and impact resistance at crack initiation and failure were recorded for the adaptive mesh beams (HB3 and HB3SF). The failure impact energy and ductility ratio of the beam HB3SF was higher than the beams HB1SF and HB2SF by more than 270 %. The results showed that the inclusion of steel fiber duplicated the optimized beam’s impact strength and ductility several times. The failure impact resistance of fibrous beams was higher than their corresponding plain beams by approximately 2300 to4460 %, while their impact ductility ratios were higher by 6.0 to 18.1 times

Trends in utilization of deceased donor kidneys based on hepatitis C virus status and impact of public health service labeling on discard

BackgroundKidneys from deceased donors infected with hepatitis C virus (HCV) are underutilized. Most HCV virus‐infected donors are designated as Public Health Service increased donors (PHS‐IR). Impact of PHS and HCV designations on discard is not well studied.MethodsWe queried the UNOS data set for all deceased donor kidneys between January 2015 and December 2018. The final study cohort donors (n = 38 702) were stratified into three groups based on HCV antibody (Ab) and NAT status: (a) Ab−/NAT− (n = 35 861); (b) Ab+/NAT− (n = 973); and (c) Ab±/NAT+ (n = 1868). We analyzed utilization/discard rates of these organs, the impact of PHS‐IR and HCV designations on discard using multivariable two‐level hierarchical logistic regression models, forecasted number of HCV viremic donors/kidneys by 2023.ResultsDuring the study period, (a) the number of viremic donor kidneys increased 2 folds; (b) the multilevel mixed‐effects logistic regression models showed that, overall, the PHS labeling (OR 1.20, CI 95% CI 1.15‐1.29) and HCV designation (OR 2.29; 95% CI 2.15‐2.43) were independently associated with increased risk of discard; (c) contrary to the general perception, PHS‐IR kidneys across all HCV groups, compared to PHS‐IR kidneys were more likely to be discarded; (d) we forecasted that the number of kidneys from HCV viremic donor kidneys might increase from 1376 in 2019 to 2092 in 2023.ConclusionHepatitis C virus viremic kidneys might represent 10%‐15% of deceased donor organ pool soon with the current rate of the opioid epidemic. PHS labeling effect on discard requires further discussion of the utility of this classification.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154409/1/tid13204_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154409/2/tid13204.pd

The temporal and long‐term impact of donor body mass index on recipient outcomes after kidney transplantation – a retrospective study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153284/1/tri13505_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153284/2/tri13505.pd

Infectious Complications in Renal Transplant Recipients

Post-kidney transplant infection is the most common life-threatening complication of long-term immunosuppressive therapy. Optimal immunosuppression, in which a balance is maintained between prevention of rejection and avoidance of infection, is the most challenging aspect of posttransplantation care. The study of infectious complications in immunologically compromised recipients is changing rapidly, particularly in the fields of prophylactic and preemptive strategies, molecular diagnostic methods, and antimicrobial agents. In addition, emerging pathogens such as BK polyomavirus and West Nile flavivirus infections and the introduction of newer immunosuppressive agents that constantly change the risk profiles for opportunistic infections has added layers of complexity to this burgeoning field. Although remarkable progress has been made in these disciplines, comprehensive understanding of the clinical manifestations of infections remains limited, and the standardization of prophylaxis, diagnosis, and treatment of most infections is yet inadequately defined. The long-term goal for optimal care of transplant recipients, with respect to infection, is the prevention and/or early recognition and treatment of infections while avoiding drug-related toxicities. © 2006 National Kidney Foundation, Inc

Mortality risk factors in chronic haemodialysis patients with infective endocarditis

Background: It is well documented that infective endocarditis (IE) is strongly associated with morbidity and mortality in haemodialysis (HD) patients. Less clear are the mortality risk factors for IE, particularly in an urban African-American dialysis population. Methods: IE patients were identified from the medical records for the period from January 1999 to February 2004 and confirmed by Duke criteria. The patients were classified as \u27survivors\u27 and \u27non-survivors\u27 depending on in-hospital mortality, and risk factors for IE mortality were determined by comparing the two cohorts. Survivors were followed as out-patients with death as the endpoint. Results: A total of 52 patients with 54 episodes of IE were identified. A catheter was the HD access in 40 patients (74%). Mitral valve (50%) was the commonest valve involved, and Gram-positive infections accounted for 87% of IE. In-hospital mortality was high (37%) and valve replacement was required for 13 IE episodes (24%). On logistic regression analyses, mitral valve disease [ P = 0.002; odds ratio (OR) = 15.04; 95% confidence interval (CI) = 2.70-83.61] and septic embolism (P = 0.0099; OR = 9.56; 95% CI = 1.72-53.21) were significantly associated with in-hospital mortality. Using the Cox proportional hazards model, mitral valve involvement (P = 0.0008; hazard ratio 4.05; 95% CI = 1.78-9.21) and IE related to drug-resistant organisms such as methicillin-resistant Staphyloccus aureus and vancomycin-resistant Enterococcus sp. (P = 0.016; hazard ratio 2.43; 95% CI = 1.18-5.00) were associated with poor outcome after hospital discharge. Conclusions: IE was associated with high mortality in our predominantly African-American dialysis population, when the mitral valve was involved, or septic emboli occurred and if MRSA or VRE were the causal organisms. © 2006 Oxford University Press

Renal Function and NODM in De Novo Renal Transplant Recipients Treated with Standard and Reduced Levels of Tacrolimus in Combination with EC-MPS

Information is lacking concerning concomitant administration of enteric-coated mycophenolate sodium with tacrolimus (EC-MPS+Tac) in renal transplant recipients (RTxR). In this 6-month, prospective, open-label, multicenter study, de novo RTxR were randomized (1 : 1) to low-dose (LD) or standard-dose (SD) Tac with basiliximab, EC-MPS 720 mg bid, and steroids. Primary objective was to compare renal function at 6-month posttransplantation. Secondary objectives were to compare the incidences of biopsy-proven acute rejection (BPAR), graft loss and death, and new-onset diabetes mellitus (NODM). 292 patients (LD n=151, SD n=141) were included. Mean Tac levels were at the low end of the target range in standard-exposure patients (SD, n=141) and exceeded target range in low-exposure patients (LD = 151) throughout the study. There was no significant difference in mean glomerular filtration rate (GFR) between treatments (ITT-population: 63.6 versus 61.0 mL/min). Incidence of BPAR was similar (10.6% versus 9.9%). NODM was significantly less frequent in LD Tac (17% versus 31%; P=0.02); other adverse effects (AEs) were comparable. EC-MPS+Tac (LD/SD) was efficacious and well tolerated with well-preserved renal function. No renal function benefits were demonstrated, possibly related to poor adherence to reduced Tac exposure

Outcome of low-dose ganciclovir for cytomegalovirus disease prophylaxis in renal-transplant recipients

To assess the outcome of low-dose-ganciclovir prophylaxis (500 mg twice a day for 3 months) in renal-transplant recipients, a retrospective analysis of 185 patients transplanted between 1998 and 2001 was performed. There were 29 (15.6%) patients who belonged to the highest risk group, donor cytomegalovirus (CMV) positive, recipient negative (D + R-), and 37 (20%) patients in the lowest risk group, D-R-. Induction immunosuppression consisted of polyclonal antibody or OKT3 (n = 62, 33.5%), interleukin-2 receptor antibody (n = 61, 33%), and no induction (n = 62, 33.5%). CMV disease occurred in 13 (7%) patients. Highest incidence was in D + R- group (17.2%), with no cases in D-R- group (P = 0.03). Tissue-invasive CMV occurred in 4 of these 13 patients. In patients developing CMV disease, there was no evidence of ganciclovir resistance and no mortality over a mean follow-up of 42 months. Low-dose ganciclovir was found to be as effective in decreasing the incidence of clinical CMV disease as high-dose ganciclovir (1 gm three times a day for 3-6 months) in previous studies

Primary Nonfunction of Renal Allograft Secondary to Acute Oxalate Nephropathy

Primary nonfunction (PNF) accounts for 0.6 to 8% of renal allograft failure, and the focus on causes of PNF has changed from rejection to other causes. Calcium oxalate (CaOx) deposition is common in early allograft biopsies, and it contributes in moderate intensity to higher incidence of acute tubular necrosis and poor graft survival. A-49-year old male with ESRD secondary to polycystic kidney disease underwent extended criteria donor kidney transplantation. Posttransplant, patient developed delayed graft function (DGF), and the biopsy showed moderately intense CaOx deposition that persisted on subsequent biopsies for 16 weeks, eventually resulting in PNF. The serum oxalate level was 3 times more than normal at 85 μmol/L (normal <27 μmol/L). Allograft nephrectomy showed massive aggregates of CaOx crystal deposition in renal collecting system. In conclusion, acute oxalate nephropathy should be considered in the differential diagnosis of DGF since optimal management could change the outcome of the allograft