Association between malnutrition-inflammation score and risk of subsequent self-reported bone fractures in prevalent kidney transplant recipients.

Chronic inflammation and protein energy wasting (PEW) syndrome are common in kidney transplant recipients (KTR). The presence of inflammation and PEW syndrome can directly affect bone resorption and bone formation, leading to bone loss and fractures. We showed PEW is independently associated with new clinically detected bone fractures in prevalent KTR. INTRODUCTION: Kidney transplant recipients (KTR) have a 4-fold higher risk of fracture compared to the general population. Chronic inflammation and PEW syndrome are common in KTR and are associated with poor outcomes. We hypothesized that the Malnutrition-Inflammation Score (MIS), a validated measure of PEW, is associated with higher risk of bone fractures in KTR. METHODS: This prospective cohort study included 839 prevalent KTR from a Central European academic center. MIS, a semiquantitative instrument of PEW, was calculated at the study entry. Self-reported history of fractures was recorded during the 2-year follow-up period. The association between MIS and bone fractures was examined in logistic regression analyses with adjustment for age, gender, eGFR, smoking habits, history of pre-transplant bone fractures, and acute rejection. RESULTS: Mean age was 51 ± 13 years, and 56% of patients were males with median (interquartile range) transplant vintage 69 (38-112) months, estimated glomerular filtration rate 55 ± 21 ml/min/1.73 m2, and calculated MIS 3 (2-4) at enrollment. Fifty-five (7%) patients experienced self-reported bone fractures during the 2-year follow-up period. Higher MIS score showed linear association with increased risk of fracture. Each one-point higher MIS was associated with 23% higher risk of bone fractures (odds ratio (OR) and 95% CI 1.23, 1.12-1.34), which remained significant after multivariable adjustments (OR 1.17, 95% CI 1.06-1.29). CONCLUSION: The MIS is independently associated with new clinically detected bone fractures in prevalent KTR.

Pre-transplant predictors of one yr weight gain after kidney transplantation.

Clinically useful predictors of weight gain could be used to reduce the epidemic of post-kidney transplant obesity and resulting co-morbidities. The purpose of this study was to identify predictors of weight gain at 12 months following kidney transplant in a cohort of 96 recipients. Demographic, clinical, and environmental data were obtained at transplant and 12 months. Descriptive, correlational, and Bayesian network analysis were used to identify predictors. For the 52 (55.9%) recipients who gained weight, the average amount gained was 9.18 ± 6.59 kg. From the 15 baseline factors that met inclusion criteria, Bayesian network modeling identified four baseline predictors for weight gain: younger age, higher carbohydrate consumption, higher trunk fat percentage, and higher perception of mental health quality of life. Three are modifiable through either pre- or immediate post-transplant clinical intervention programs.

Going paperless: improved cataract surgery outcome data quality in a new fully electronic unit.

OBJECTIVES: To report outcome data on the first 5000 consecutive cataract cases at a new paperless eye unit and benchmark against the Royal College of Ophthalmologists' National Ophthalmology Database (RCOphth NOD). METHODS: Using the in-built audit tool of the electronic medical records system, data from all cataract operations performed between 1 April 2014 and 13 January 2017 were compiled. RESULTS: Five thousand and eight cases were recorded of which the overall intra-operative complication rate was 2.4%, the most common being posterior capsular rupture-1.14%. Follow-up data on post-operative complications were recorded in 98.6% of cases. Pre- and post-operative visual acuities was measured in 98.0% of cases. In all, 40.8% of eyes achieved a visual acuity of 6/6 or better and 90.7% achieved 6/12 or better. CONCLUSIONS: A data set of >5000 consecutive cataract operations was obtained in this eye department. The recording of pre- and post-operative visual acuity in 98% of cases compare very favourably to the RCOphth NOD Audit Report 2017 where pre- and post-operative visual acuities were recorded in only 57.1% of operations. Despite this difference, the outcome measures from this unit and RCOphth NOD were very similar, validating the results of the RCOphth NOD audit reports. Significantly, when applying the RCOphth NOD audit criteria for measuring post-operative visual acuity, approximately 15% of cases were excluded from the data set, reducing the completeness of the data set. Paperless ophthalmology units are feasible in today's NHS and can produce near complete cataract data sets; this can ultimately lead to more comprehensive and reliable aggregate cataract outcome data.

Proceedings of Consensus Conference on Simultaneous Liver Kidney Transplantation (SLK).

A consensus conference sponsored by the American Society of Transplant Surgeons (ASTS), American Society of Transplantation (AST), United Network for Organ Sharing (UNOS) and American Society of Nephrology (ASN) convened to examine simultaneous liver-kidney transplantation (SLK). Directors from the 25 largest liver transplant programs along with speakers with recognized expertise attended. The purposes of this conference were to propose indications for SLK, to establish a prospective data registry and, most importantly, to recommend standard listing criteria for these patients. Scientific registry of transplant recipients data, and single center data regarding chronic kidney disease (CKD) and acute kidney injury (AKI) in conjunction with liver failure as a basis for SLK was presented and discussed. The consensus was that Regional Review Boards (RRB) should determine listing for SLK, as with other MELD exceptions, with automatic approval for: (i) End-stage renal disease with cirrhosis and symptomatic portal hypertension or hepatic vein wedge pressure gradient >/= 10 mm Hg (ii) Liver failure and CKD with GFR /= 2.0 mg/dL and dialysis >/= 8 weeks (iv) Liver failure and CKD and biopsy demonstrating > 30% glomerulosclerosis or 30% fibrosis. The RRB would evaluate all other requests to determine appropriateness.

Should liver transplantation be performed for patients with hepatitis B?

Because of the almost universal recurrence of hepatitis B surface antigenemia (HBsAg) after liver transplantation, some centers have questioned whether these patients are appropriate allograft candidates. Since January 1984, 51 patients with hepatitis B (HBV) underwent OLT at our center. No therapy was given to prevent reinfection. Three patients underwent retransplantation. The indications for transplant included fulminant HBV (13 patients), chronic HBV (33 patients), and hepatocellular carcinoma (HCCA) in addition to HBV (5 patients). Incidental HCCA was found in 2 of the 33 patients thought to have only chronic HBV. Actuarial survival for the entire group was 57% at 1 year and 54% at 3 years. Of the 23 patients who died, only 4 deaths were attributable to recurrent HBV liver disease. Four patients survived less than 4 days due to primary graft nonfunction. Ten patients died in the first 3 months from sepsis. Although all patients who died beyond 30 days had recurrent HBsAg, only 4 deaths were attributable to recurrent HBV. The remaining 5 deaths were caused by portal vein thrombosis, bile leak, lymphoma, pancreatitis, and sepsis occurring at 15 months. Excluding the 4 patients who died from primary graft nonfunction, actuarial survival was 63% at 1 year and 60% at 3 years. Of the 28 survivors, 24 are HBsAg positive; however, only 5 have recurrent HBV liver disease. Multiple factors were evaluated to determine their influence on survival; i.e., HBV serology, United Network for Organ Sharing status, fulminant versus chronic HBV, incidence of rejection, immunosuppression, transfusion requirements, and presence of HCCA. Of these, only the presence of HCCA adversely affected outcome. Of the 7 patients with HCCA and HBV, 6 patients died within the first 6 months and 1 patient has recurrent HBV liver disease at 25 months. Actuarial survival excluding those patients with HCCA was 64% at 1 year and 61% at 3 years. Based on our results, patients with HBV and associated HCCA have a poorer prognosis and should probably be excluded from transplantation. Although the survival for patients with HBV undergoing liver transplantation is inferior to that expected in patients with some other diagnoses, long-term survival can be achieved in a majority of these patients despite recurrence of HBsAg. We believe that appropriately selected patients with a diagnosis of HBV alone should continue to be candidates for liver allografts.

Biological effects and fate of a soluble, dimeric, 80-kDa tumor necrosis factor receptor in renal transplant recipients who receive OKT3 therapy.

A preliminary clinical study of renal allograft recipients revealed that a dimeric form of the human 80 kDa soluble receptor (sTNFR:Fc) for tumor necrosis factor (TNF) is well tolerated and attenuates the OKT3-induced acute clinical syndrome. The current study determined the in vivo biological effects and fate of sTNFR:Fc in these patients. Serial assessment of both antigenic and biological activities of circulating TNF and sTNFR:Fc have led to the following observations. (1) Although control patients typically responded to the first OKT3 injection with a rapid increase of biologically active TNFalpha, patients on sTNFR:Fc therapy had markedly higher serum TNFalpha antigenic levels, but no detectable bioactivity. Thus, sTNFR:Fc functioned as a potent antagonist, despite its cytokine-carrier effect. (2) Peak sTNFR:Fc levels averaging 800 and 2500 ng/ml were routinely achieved in vivo, using the low-dose (0.05 mg/kg) and high-dose (0.15 mg/kg) protocols. (3) The half-life of circulating sTNFR:Fc was estimated to be approximately 4.4 days, and levels of p80 receptors in treated patients remained significantly above those in control patients for at least 20 days. (4) In vitro blocking studies demonstrated that circulating sTNFR:Fc remained biologically active for 2 weeks. These results demonstrate that under current protocols, significant serum levels of sTNFR:Fc, capable of effectively neutralizing TNF activity over prolonged periods, can be achieved. The persistent OKT3 side effects observed, despite sTNFR:Fc therapy, are therefore likely to be caused by factors other than TNF.

Transjugular portosystemic shunts in pediatric patients awaiting liver transplantation.

Three pediatric patients from 6 to 11 years of age awaiting liver transplantation for end stage liver disease underwent transjugular intrahepatic portosystemic shunt (TIPS) placement for control of variceal bleeding. Two of the three procedures were performed emergently after endoscopic sclerotherapy failed to stop active bleeding. One procedure was performed electively after multiple prior bleeding episodes. The shunts were created from the middle or left hepatic vein to the left portal vein, and none of the subsequent transplant surgeries was complicated by the presence of the stents. No major or minor complications were related to TIPS placement. Two patients underwent concomitant variceal embolization. Bleeding was successfully controlled in each patient. We conclude that TIPS placement in children is technically feasible, does not complicate subsequent surgery, and is useful treating acute variceal hemorrhage in pediatric patients awaiting liver transplantation.

Evaluation of recombinant human soluble dimeric tumor necrosis factor receptor for prevention of OKT3-associated acute clinical syndrome.

Tumor necrosis factor alpha (TNFa) has been shown to be the primary cytokine responsible for the OKT3-induced acute clinical syndrome (OKT3-ACS). Recombinant human soluble tumor necrosis factor receptor (TNFR:Fc) is a dimer of the p80 TNF receptor, which binds both TNFa and lymphotoxin (LT). Renal allograft recipients undergoing OKT3 therapy for steroid-resistant rejection were randomized to receive OKT3 alone or in combination with TNFR:Fc to determine its safety and efficacy in decreasing the severity of OKT3-ACS and in restoring renal function. Six of 12 patients were given TNFR:Fc prior to each of the first two injections of OKT3. All patients were monitored for manifestations of OKT3-ACS and changes in renal function. In addition, serial serum samples were assayed for TNFa and TNFR:Fc levels (ELISA) and TNFa bioactivity (L929). No adverse side effects were identified in patients receiving TNFR:Fc. Patients treated with TNFR:Fc had significantly fewer symptoms by day 2 of OKT3, and had a lower overall incidence of chills and arthralgias. Renal dysfunction reversed within 24 hr in the TNFR:Fc-treated group in contrast to the 48-72-hr delay in the control group. Antigenic TNFa levels increased in the control group from < 10 pg/ml pre OKT3 to a mean peak level of 30 +/- 13 pg/ml on day 1 and decreased to pretreatment levels by day 2. TNFR:Fc-treated patients had a mean peak TNFa level of 235 +/- 135 pg/ml, suggesting a carrier effect of TNFR:Fc. In contrast, bioactivity was barely detectable (mean 20 +/- 14 pg/ml) in the day 1 samples from TNFR:Fc-treated patients, whereas significant bioactivity (peak mean 60 +/- 35 pg/ml) was detected in sera from control patients. TNF receptor levels reached 600 ng/ml in treated patients and remained elevated for up to 18 days confirming the long half-life of TNFR:Fc. This phase 1 trial demonstrates that TNFR:Fc is well tolerated and may limit the severity of OKT3-ACS. The most significant observation was a more rapid improvement in renal function in the TNFR:Fc-treated patients. The absence of TNFa bioactivity indicates that TNFR:Fc functions as a TNF antagonist. Further evaluation of higher doses of TNFR:Fc in OKT3-treated patients is currently in progress.

Mixed allogeneic chimerism and renal allograft tolerance in cynomolgus monkeys.

We have developed a nonmyeloablative preparative regimen that can produce mixed chimerism and renal allograft tolerance between MHC-disparate nonhuman primates. The basic regimen includes ATG, nonmyeloablative total-body irradiation (TBI, 300 rads), thymic irradiation (TI, 700 rads), and donor bone marrow infusion. Kidney allografts from MHC-mismatched donors were transplanted with various manipulations of the preparative regimen. Monkeys treated with the basic regimen alone (n = 2) rejected allografts by day 15. With the addition of cyclosporine (CsA) for one month (n = 3), one monkey developed multilineage mixed chimerism and renal allograft tolerance thereafter (> 430 days). To reduce the toxicity of the preparative regimen, TBI was fractionated to 150 rads on two successive days in subsequent studies. All monkeys receiving this modified regimen (n = 4) developed multilineage chimerism with fewer side effects and accepted renal allografts long-term with no further immunosuppression (196 days, 198 days, > 150 days, and > 40 days). In long-term survivors, donor-specific nonreactivity was confirmed by MLR and skin transplantation. Three monkeys treated with the basic regimen plus CsA but with only 150 rads of TBI (n = 1) or no TBI (n = 2) did not develop multilineage chimerism and grafts were rejected (day 40-50) soon after the CsA discontinuation. Monkeys treated with the same regimen, but without DBM (n = 2), rejected kidney allografts by day 52. Therefore, at least transient engraftment of DBM appears to be essential for induction of donor specific tolerance in this monkey model.

Inhibition of the effects of TNF in renal allograft recipients using recombinant human dimeric tumor necrosis factor receptors.

Tumor necrosis factor alpha (TNFa) and lymphotoxin (LT) or TNF beta are closely linked cytokines produced by macrophages and activated T lymphocytes, which play important regulatory roles in the immune response to allografts. They have also been implicated as mediators of the adverse reactions observed during OKT3 therapy. Therefore, anti-TNF agents could be useful both for immunosuppression and for limiting the systemic response observed in patients receiving OKT3. Recombinant TNFR:Fc is a fusion protein that binds TNFa and LT, thereby neutralizing their effects in vitro. The present study investigates the potential clinical application of TNFR:Fc in a nonhuman primate renal allograft model. Cynomolgus renal allograft recipients were treated with TNFR:Fc induction therapy alone or in combination with subtherapeutic doses of cyclosporine. Control animals received no immunosuppression or subtherapeutic cyclosporine. TNFR:Fc, administered as the only immunosuppressive agent, successfully prolonged renal allograft survival in the majority of treated animals. The prolongation of allograft survival was even more impressive when TNFR:Fc was combined with subtherapeutic doses of cyclosporine. Onset of rejection was significantly delayed as well in the TNFR:Fc treated groups. No adverse side effects were observed in any of the TNFR:Fc treated animals. Precursor cytotoxic T cells were detected in peripheral blood samples of treated recipients but the level of effector CTLs in vivo was below the threshold of detection. These results demonstrate that TNFR:Fc can be safely administered and is effective in prolonging renal allograft survival and in delaying the onset of rejection when administered alone or in combination with cyclosporine.

Sexually dimorphic expression of myosin heavy chains in the adult mouse masseter.

Little is known regarding the role of androgenic hormones in the maintenance of myosin heavy chain (MHC) composition of rodent masticatory muscles. Because the masseter is the principal jaw closer in rodents, we felt it was important to characterize the influence of androgenic hormones on the MHC composition of the masseter. To determine the extent of sexual dimorphism in the phenotype of masseter muscle fibers of adult (10-mo-old) C57 mice, we stained tissue sections with antibodies specific to type IIa and IIb MHC isoforms. Females contain twice as many fibers containing the IIa MHC as males, and males contain twice as many fibers containing the IIb MHC as females. There is a modest amount of regionalization of MHC phenotypes in the mouse masseter. The rostral portions of the masseter are composed mostly of type IIa fibers, whereas the midsuperficial and caudal regions contain mostly type IIb fibers. Using immunoblots, we showed that castration results in an increase in the expression of type IIa MHC fibers in males. Ovariectomy has no effect on the fiber type composition in females. We conclude that testosterone plays a role in the maintenance of MHC expression in the adult male mouse masseter.

Skeletal muscle grids for assessing current distributions from defibrillation shocks.

This paper utilizes a structured and an unstructured grid representation of a torso with an anisotropic skeletal muscle to assess current distributions from defibrillation shocks. The results show that a finite-element solution on an unstructured grid of 400,000 elements (60,000 nodes) achieves comparable current distributions with a finite-difference solution on a structured grid that uses approximately the same number of nodes. Moreover, a finite-element solution on a 65,000-element (10,500 nodes) unstructured grid yielded fractional percent current results within 5% of the finer grids. The structured and unstructured grid models are used to investigate recent interpretations of experimental data that concluded that more than 80% of the total defibrillation current is shunted by the anisotropic skeletal muscle thoracic cage. It is concluded that these interpretations, which were based on a one-dimensional resistive network representation of the three-dimensional defibrillation situation, overestimate by 25% the current shunted by the anisotropic thoracic cage.

Pupil size and reactivity following hydroxypropyl methylcellulose and sodium hyaluronate.

AIMS: A prospective randomised clinical trial was set up to compare the effect of hydroxypropyl methylcellulose (Ocucoat) and sodium hyaluronate (Healonid) on pupil size and reactivity following their use in cataract surgery. METHODS: Pupil measurements were recorded before and 6 weeks after surgery. RESULTS: There was no significant difference between the two groups with respect to pupil size (p = 0.69, Mann-Whitney U test) nor with respect to reactivity (p = 0.99, Fischer's exact test). Ninety six per cent of the surgery was performed using phacoemulsification. CONCLUSION: This trial suggests that both viscoelastic materials have similar effects on the pupil after their use in cataract surgery.

Aminophylline toxicity--how many hospital asthma deaths does it cause?

Aminophylline administration was compared in 43 patients who died from asthma and 43 matched controls who were admitted, suffering from acute asthma, to hospitals in the North East Thames Region. A computer program, which used information about individual characteristics, medical history and drug intake, was employed to calculate the serum theophylline levels which were likely to have resulted from the hospital treatment each patient received. Toxic theophylline levels were estimated to have occurred in 21% (9/43) of fatal cases and 7% (3/43) controls. Details of four patients who died when their serum theophylline levels were likely to have been very high are presented. Six fatal cases suffered gastro-intestinal bleeds during their final illness: four of these had theophylline levels which were calculated to have been toxic at the time of bleeding.

A simulation study evaluating the performance of high-density electrode arrays on myocardial tissue.

Multielectrode arrays used to detect cellular activation have become so dense (electrodes per square millimeter) as to jeopardize the basic assumptions of activation mapping; namely, that electrodes are points adequately separated as to not interfere with the tissue or each other. This paper directly tests these assumptions for high-density electrode arrays. Using a finite element model with modified Fitzhugh-Nagumo kinetics, we represent electrodes as isopotential surfaces of varying widths and spacing ratio (SR) (center-to-center spacing divided by electrode width). We examine the signal strength and ability of a single electrode to detect activation due to a passing wavefront. We find that high-density arrays do not cause significant wavefront curvature or alter activation timing in the underlying tissue. Relationships between signal strength, cross talk, and array design are explained by the interaction of the propagating wavefront and induced sources on the isopotential electrodes. Sensitivity analysis shows that these results may be generalized to a wide range of physiologically relevant designs and applications. We conclude that electrode array designs in which electrode spacing greatly exceeds electrode diameter are overly conservative and that arrays with a SR of less than 2.0 may perform successfully in electrophysiological studies.

Membrane polarization induced in the myocardium by defibrillation fields: an idealized 3-D finite element bidomain/monodomain torso model.

This study develops a three-dimensional finite element torso model with bidomain myocardium to simulate the transmembrane potential (TMP) of the heart induced by defibrillation fields. The inhomogeneities of the torso are modeled as eccentric spherical volumes with both the curvature and the rotation features of cardiac fibers incorporated in the myocardial region. The numerical computation of the finite element bidomain myocardial model is validated by a semianalytic solution. The simulations show that rotation of fiber orientation through the depth of the myocardial wall changes the pattern of polarization and decreases the amount of cardiac tissue polarized compared to the idealized analytic model with no fiber rotation incorporated. The TMP induced by transthoracic and transvenous defibrillation fields are calculated and visualized. The TMP is quantified by a continuous measure of the percentage of myocardial mass above a potential gradient threshold. Using this measure, the root mean square differences in TMP distribution produced by reversing the electrode polarity for anterior-posterior and transvenous electrode configurations are 13.6 and 28.6%, respectively. These results support the claim that a bidomain model of the heart predicts a change of defibrillation threshold with reversed electrode polarity.

Case report: acute cellulitis and lymphadenitis caused by mucoid Streptococcus pyogenes.

Most patients with acute cellulitis due to Streptococcus pyogenes have a striking onset of high fever and systemic toxicity. Even if hospitalization is deemed necessary for initial treatment, most patients respond promptly to appropriate antibiotic therapy and can be managed as outpatients for most of the treatment regimen. Described is a 48-year-old, previously healthy woman with acute cellulitis and lymphadenitis who did not initially respond to treatment despite proved in vitro activity against the patient's S. pyogenes isolate. The strain grew as a mucoid colony phenotype on blood agar plates. The mucoid characteristic of the strain may have accounted for the patient's lack of response to initial therapy, and previously published clinical and laboratory data support this impression.

Investigation of sexual dimorphism in the rabbit masseter muscle showing different effects of androgen deprivation in adult and young adult animals.

To evaluate the role played by androgens in the development and maintenance of sex differences in the proportion of muscle fibres of different phenotypes, the effects of castration in adult (>6 months old) and in young adult (2-3 months old) male rabbits was examined. Immunohistochemical methods were used to evaluate the proportion of muscle fibres containing different myosin heavy-chain isoforms in 10 different neuromuscular compartments of the masseter. In young adult animals of both sexes, the proportion of fibres of different phenotypes in different compartments was not significantly different from that of normal adult females. In animals castrated as young adults, the development of adult male phenotype proportions was completely blocked in most compartments. In animals castrated as adults, proportions were not significantly different from those of the intact males. For most masseter compartments, androgens produced permanent changes in muscle fibre phenotype during a critical period of postnatal development. However, in the posterior deep compartment, androgen deprivation in young adults had no effect on phenotype proportions, but castration of adults resulted in a striking increase in the proportion of fibres containing the IIa myosin heavy-chain isoform.

Detrimental effects of short-term glucocorticoid use on the rat diaphragm.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the effect of short-term, high doses of glucocorticoids on both body and diaphragm weights as well as contractile characteristics of the rat diaphragm. SUBJECTS: Adult, female Sprague-Dawley rats were divided into 2 groups: a control group (n=16) and a prednisolone group (n=16). METHODS: The prednisolone group received prednisolone at a dosage of 5 mg/kg, and the control group received sham saline injections for 5 days. Animals were weighed prior to and after completion of the drug injection period. At the completion of the drug injection period, the animals were sacrificed, and the diaphragm, soleus, and extensor digitorum longus muscles were removed and weighed. A small strip of the costal diaphragm was connected to a force transducer, and the following contractile characteristics were measured: maximal specific isometric tetanic tension, peak isometric twitch specific tension, one-half relaxation time, and time to peak tension. RESULTS: Both body and diaphragm weights decreased by 15% in the prednisolone group as compared with the control group. Maximal specific isometric tetanic tension was reduced 13% in the prednisolone group as compared with the control group. There was no difference in any twitch contractile characteristics between the 2 groups. CONCLUSION AND DISCUSSION: These data support the hypothesis that glucocorticoid treatment over a 5-day period results in a decrease in specific tension as well as diaphragm and body weight. These results may have implications for the treatment of patients receiving high doses of glucocorticoids for acute medical conditions.

The Effects of Prophylactic Brace Construction Materials on the Reactive Responses of the MCL During Repetitive Impacts.

OBJECTIVE: The purpose of the present study was to investigate the effect of different construction materials on the ability of a prophylactic brace to reduce the stresses sustained by a surrogate medial collateral ligament (MCL) under low-energy repetitive impact conditions. DESIGN AND SETTING: A surrogate leg was fixed at both the hip and foot with the knee in full extension. A prophylactic brace was attached to the surrogate leg and the system struck by an impactor weighing either 6.68 kg or 16.9 kg. SUBJECTS: A single brace design (Am Pro Knee Guard) was used. Three different materials (nylon, aluminum, graphite) were used in constructing the brace uprights. MEASUREMENTS: Tension in the MCL was measured under all conditions of brace material and impactor weight. In addition, the impact impulse response of the system was evaluated. RESULTS: The graphite and aluminum uprights showed significant reductions in both MCL peak tension magnitude (from 12 to 21% improvement) and in the impulse response of the MCL (from 36 to 47% improvement) when compared to the no-brace condition. CONCLUSIONS: The present study indicates that the choice of brace upright material does have a significant effect on the transmission and absorption of low-level repetitive impact forces at the MCL and should be an important consideration in the design of better knee braces.