Mechanically transduced immunosorbent assay to measure protein-protein interactions.

Measuring protein-protein interaction (PPI) affinities is fundamental to biochemistry. Yet, conventional methods rely upon the law of mass action and cannot measure many PPIs due to a scarcity of reagents and limitations in the measurable affinity ranges. Here, we present a novel technique that leverages the fundamental concept of friction to produce a mechanical signal that correlates to binding potential. The mechanically transduced immunosorbent (METRIS) assay utilizes rolling magnetic probes to measure PPI interaction affinities. METRIS measures the translational displacement of protein-coated particles on a protein-functionalized substrate. The translational displacement scales with the effective friction induced by a PPI, thus producing a mechanical signal when a binding event occurs. The METRIS assay uses as little as 20 pmols of reagents to measure a wide range of affinities while exhibiting a high resolution and sensitivity. We use METRIS to measure several PPIs that were previously inaccessible using traditional methods, providing new insights into epigenetic recognition.

Failure modes of current total ankle replacement systems.

Methodology for evaluation of total ankle replacements is described. Fusion and its problems are discussed as are those of total ankle joint replacement. Fusion is an imperfect solution because it reduces ankle functionality and has significant complications. Early fixed-bearing total ankles were long-term failures and abandoned. Currently available fixed-bearing ankles have proved inferior to fusion or are equivalent to earlier devices. Only mobile-bearing devices have been shown reasonably safe and effective. One such device, the STAR, has been approved by the Food and Drug Administration after a rigorous controlled clinical trial and is available for use in the United States.

Epidemiology of acute renal failure in ICUs: a multi-center prospective study.

BACKGROUND AND AIM: Acute kidney injury (AKI) is a common complication in intensive care units (ICUs). However, its incidence and outcome vary in several studies depending on definitions used or even the geographic origin of the study. We aimed to evaluate the epidemiology of AKI in ICUs in Greece. METHOD: Prospective multicenter study of ICU patients presented with AKI during a 3-month period. RESULTS: One-hundred and seventy patients presented with AKI (16% of total admissions in 23 ICUs). The most common contributing factor to AKI was sepsis (45%). Half of the patients required renal replacement therapy, which was mainly managed by ICU clinicians. Nearly 65% of the AKI patients died, whereas 15% were discharged with renal impairment. Age (RR 1.01, p = 0.046), sepsis (RR 1.62, p = 0.015) and urine output (RR 0.99, p = 0.009) were independently associated with outcome. CONCLUSION: AKI involves a large number of patients in Greek ICUs and is associated with adverse outcomes.

Biomechanical comparison of callus over a locked intramedullary nail in various segmental bone defects in a sheep model.

BACKGROUND: Little has been written about the size of a bone defect that can be restored with one-stage lengthening over a reamed intramedullary nail. MATERIAL/METHODS: Sixteen adult female sheep were divided into four main groups: a simple osteotomy group (group I) and three segmental defect groups (1-, 2-, and 3-cm gaps, groups II-IV). One intact left tibia from each group was also used as the non-osteotomized intact control group (group V). In all cases, the osteotomy was fixed with an interlocked Universal Humeral Nail after reaming to 7 mm. Healing of the osteotomies was evaluated after 16 weeks by biomechanical testing. The examined parameters were torsional stiffness, shear stress, and angle of torsion at the time of fracture. RESULTS: The regenerate bone obvious in x-rays in the groups with 1- and 2-cm gaps had considerable mechanical properties. Torsional stiffness in these two groups was nearly equal and its value was about 60% of the stiffness of the simple osteotomy group. Gradually decreasing stiffness was observed as the osteotomy gap increased. No significant differences were found among the angles of torsion at fracture for the various osteotomies or the intact bone. These results showed that the group with 1-cm gap had 65% of the shear stress at failure of the simple osteotomy group. CONCLUSIONS: The authors believe that there is evidence indicating that intramedullary nailing could be a reasonable option when one-stage lengthening of a long bone by 1 or 2 cm is contemplated.

Sevelamer hydrochloride versus aluminum hydroxide: effect on serum phosphorus and lipids in CAPD patients.

BACKGROUND: Dietary phosphorus restriction, oral administration of phosphorus binders, and dialysis are the main strategies to control hyperphosphatemia in patients with stage 5 chronic kidney disease. Aluminum hydroxide (AH) and calcium carbonate, the most commonly used phosphorus binders, have serious disadvantages, such as aluminum toxicity and hypercalcemia. Sevelamer hydrochloride (SH) is a relatively new nonabsorbed calcium- and aluminum-free phosphorus binder. The present study was designed to evaluate the efficacy of SH in the control of hyperphosphatemia and its effect, compared to AH, on serum lipid parameters in patients on continuous ambulatory peritoneal dialysis (CAPD). METHODS: 30 stable patients on CAPD were included in an open-label, randomized crossover study. After a 2-week phosphorus binder washout period, 15 patients (group I) were administered SH for 8 weeks and in the remaining patients (group II), AH was introduced (phase A). After a new 2-week washout period, patients crossed over to the alternate agent for another 8 weeks (phase B). RESULTS: There were similar reductions in serum phosphorus levels over the course of the study with both agents: by 1.18 +/- 0.07 mg/dL (0.38 +/- 0.03 mmol/L) with SH and by 1.25 +/- 0.15 mg/dL (0.40 +/- 0.05 mmol/L) with AH in phase A (p = NS), and by 1.35 +/- 0.25 mg/dL (0.43 +/- 0.08 mmol/L) with AH and by 1.23 +/- 0.80 mg/dL (0.39 +/- 0.25 mmol/L) with SH in phase B (p = NS). Moreover, SH administration was associated with a 10.5% +/- 9.4% and a 20.1% +/- 6.8% fall in total cholesterol (p < 0.05) and low-density Lipoprotein cholesterol (p < 0.001) in phase A, and 11.9% +/- 7.2% (p < 0.05) and 21.5% +/- 2.4% (p < 0.001), respectively, in phase B. In both phases of the study, AH administration was not followed by a significant change in serum lipid parameters. CONCLUSION: Sevelamer hydrochloride is a well-tolerated alternative to calcium- or aluminum-containing phosphorus binder in the control of serum phosphorus in CAPD patients. Furthermore, SH improves the lipid profile in these patients.

Two- to 12-year evaluation of cementless Buechel-Pappas total hip arthroplasty.

A unique, straight-stemmed, proximally porous-coated, modular hip arthroplasty system, coated with thin-film (5- to 9-microm), titanium-nitride ceramic, was used clinically in 130 hip arthroplasties in 117 patients who were followed over a 2- to 12-year interval (mean, 6.45 years). Harris Hip Scores demonstrated 82.3% excellent, 15.4% good, 2.3% fair, and 0% poor results. Thigh pain that limited activities of daily living was seen in 0.8% (1 of 130) hips. Kaplan-Meier survival estimates using an endpoint of revision of any component for any reason demonstrated an overall survival of 95.5% during the 12-year interval. Cementless fixation survivorship of the acetabular and femoral components was 98.5% during the 12-year interval.

Twenty-year evaluation of cementless mobile-bearing total ankle replacements.

Two consecutive series of patients who had cementless, porous-coated, congruent-contact, mobile-bearing total ankle replacements were evaluated during a 20-year interval using the New Jersey Orthopaedic Hospital ankle scoring scale to determine clinical outcome and overall implant survivorship with revision as an end point. The initial series of 38 patients (40 ankle replacements) using a shallow-sulcus design had diagnoses of: osteoarthritis, seven (17.5%); rheumatoid arthritis, nine (22.5%); posttraumatic arthritis, 21 (52.5%); and failed fusion, three (7.5%). Clinical results after 2-20 years, (mean, 12 years) were 28 (70%) good to excellent, two (5%) fair, and 10 (25%) poor. Postoperative ankle motion ranged from 10 degrees-47 degrees total arc (mean, 25 degrees total arc). The 20-year overall survivorship for the shallow-sulcus design was 74.2%. A second series of 74 patients (75 ankle replacements) using a deep-sulcus design had diagnoses of: osteoarthritis, eight (11%); rheumatoid arthritis, nine (12%); osteonecrosis, three (4%); and posttraumatic arthritis, 55 (73%). Clinical results after 2-12 years, (mean 5 years) were 66 (88%) good to excellent, four (5%) fair, and five (7%) poor. Postoperative ankle motion ranged from 10 degrees-50 degrees total arc (mean, 29 degrees total arc). The 12-year overall survivorship for the deep-sulcus design was 92%.

Magnesium homeostasis in patients undergoing continuous ambulatory peritoneal dialysis: role of the dialysate magnesium concentration.

We carried out this retrospective study to examine the magnesium status of our chronic ambulatory peritoneal dialysis (CAPD) patients dialyzed with 0.75 mmol/L (group I) or 0.50 mmol/L (group II) magnesium peritoneal dialysis solution. A total of 34 anuric patients on CAPD (age:31-72 years; duration of CAPD:7-74 months) were studied. None of them received magnesium-containing phosphate binders or vitamin D. Biochemical parameters including magnesium, calcium, phosphate, parathormone, and albumin were measured in all patients. The corrected for hypoalbuminemia serum magnesium concentration in group I was significantly higher compared to that found in group II. However, there were no significant differences in the other measured parameters between the two groups of CAPD patients, though iPTH levels were somewhat increased in group II patients. Serum magnesium levels were weakly correlated with serum prealbumin levels in both groups of CAPD patients (r=0.16, P=0.08 and r=0.17, P=0.07). The incidence of hypermagnesemia was significantly higher in group I patients versus those in group II (13/19 68.4%] vs. 2/15 13.3%], P<0.01). On the other hand, no patient developed hypomagnesemia (corrected total magnesium <0.65 mmol/L), despite the trend toward decreased magnesium levels in group II patients. Our results point out that serum iPTH levels and nutritional parameters, such as prealbumin levels, should be taken into account in the choice of the magnesium concentration of the peritoneal dialysis fluid.

Ten-year evaluation of cementless Buechel-Pappas meniscal bearing total ankle replacement.

A porous-coated, cementless, congruent-contact, three-piece, meniscal-bearing total ankle replacement was developed and used clinically over a 2- to 10-year period for patients with disabling ankle arthritis. Polished titanium-nitride ceramic-coated Ti6Al4V tibial and talar components with a deep-sulcus trochlear groove and two lateral fixation fins for the talar onlay component were used. The ultra-high-molecular-weight polyethylene (UHMWPe) meniscal bearing congruently conformed to the flat upper tibial component surface and the deep sulcus and cylindrical geometry of the lower talar component surface. Fifty deep-sulcus (Buechel-Pappas) total ankle replacements were implanted in 49 patients. Diagnoses were 8 osteoarthritis (16%), 7 rheumatoid arthritis (14%), 2 avascular necrosis (4%), and 33 post-traumatic arthritis (66%). Ages ranged from 26 to 71 years (mean 49 years). Clinical results using a strict ankle scoring system demonstrated good/excellent results in 88% of cases. Postoperative ankle motion ranged from 12 degrees to 46 degrees total arc (mean 28 degrees), which was similar to the preoperative motion. Revision for malalignment was necessary in two cases (4%). Mechanical complications included one case of meniscal bearing wear (2%) in a patient with post-traumatic arthritis with component malalignment and one case of talar component subsidence (2%) in a patient with avascular necrosis of the talus. No tibial component loosening was seen. Cumulative survivorship using an end point of revision of any component for any reason was 93.5% at 10 years (confidence interval 61-100%).

Twenty-year evaluation of the New Jersey LCS Rotating Platform Knee Replacement.

Clinical results of the initial cemented and cementless series of 233 New Jersey Low Contact Stress Rotating Platform Knee Replacements in 184 patients surviving at least 10 years were analyzed using a strict knee scoring scale. The study showed excellent (46.7%) and good (53.3%) results in primary cemented rotating platform knee replacements, and excellent (68.1%), good (29.8%), and fair (2.1%) results in primary cementless rotating platform knee replacements. Radiographic evaluation at a minimum 10-year follow-up showed stable fixation of all components, no gross migration but significant osteolysis requiring bearing exchange, and bone grafting in three cementless rotating platform knee replacements (1.8%) in three patients who underwent previous surgeries at an average 10.2 years from the index surgery. Survivorship of the patients who underwent primary cemented rotating platform knee replacements with end points of revision for any mechanical reason or a poor clinical knee score was 97.7% at 10 and 20 years. Survivorship of the patients who underwent cementless rotating platform knee replacements with end points of revision for any mechanical reason or a poor clinical knee score was 98.3% at 10 and 18 years.

Pharmacokinetics of teicoplanin in patients undergoing chronic haemodialysis.

In order to define a dose regimen of teicoplanin for patients undergoing chronic haemodialysis so that they achieved trough drug serum levels above 10 mg/l, two single doses of 5 and 10 mg/kg were administered intravenously in seven anuric patients immediately after the end of haemodialysis. Concentrations of teicoplanin were determined by a microbiological assay in samples collected from peripheral veins via the arterial and the venous lines of the fistulae and from the dialysate during haemodialysis. The administration of a 5 and 10 mg/kg dose gave mean C(max) of 62.80 and 122.43 mg/l, mean AUC of 526.43 and 1103.98 mg h/l, mean half life (t(1/2)) of 109.09 and 107.06 h, mean clearance rates of 12.85 and 12.44 ml/min, mean apparent volumes of distribution of 1.68 and 1.68 l/kg and mean volumes of distribution at steady state of 0.31 and 0.28 l/kg, respectively. Trough serum levels above 10 mg/l were found for 24 h after the administration of the 5 mg/kg dose and for 48 h after the administration of the 10 mg/kg dose. Teicoplanin was not detected in the dialysate. Its concentrations in both the arterial and the venous lines of the fistulae were similar. Based on the time period after the administration of teicoplanin where the desired trough serum levels were found and on the observed t(1/2), it is proposed that teicoplanin should be administered at a dose of 10 mg/kg at 48-72 h intervals, in patients undergoing chronic haemodialysis for the therapy of infections caused by Gram-positive cocci.

La prueba dot-ELISA para la detección de campo de la leishmaniasis visceral en Honduras / Field use of the dot-ELISA test for visceral leishmaniasis in Honduras

En una zona endémica de la República de Honduras, se llevó a cabo un ensayo sobre el terreno de la prueba de inmunoabsorbencia ligada a la enzima efectuada en disco de nitrocelulosa (dot-ELISA), como microtécnica rápida y susceptible de interpretarse a simple vista, para el diagnóstico serológico de la leishmaniasis visceral en el hombre. De los 305 sujetos investigados usando una dilución del suero de 1:32, se observaron reacciones positivas en ocho de los nueve casos de leishmaniasis visceral diagnosticada mediante estudio parasitológico que habían recibido tratamiento, en 13 de los 45 familiares de pacientes (grupo expuesto a un gran riesgo) y en ocho de los 244 niños seleccionados al azar en la zona endémica. Se observaron reacciones cruzadas en uno de los tres niños con leishmaniasis cutánea confirmada por estudio parasitológico y en tres de los cuatro adultos con resultados serológicos positivos para enfermedad de Chagas. La determinación de los títulos de punto final de los sueros de los pacientes con leishmaniasis visceral produjo títulos recíprocos que fluctuaron entre 512 y 8 192, inferiores a los que por lo general se encuentran en casos activos no tratados. Esta prueba no requiere instalaciones eléctricas y todos los materiales pueden transportarse fácilmente a pie. Es un procedimiento rápido, sencillo, poco costoso y, no obstante, sensible y relativamente específico en las condiciones propias del terreno. Podría resultar un instrumento valioso para los servicios de atención primaria de salud y para las encuestas epidemiológicas en las numerosas zonas endémicas donde actualmente no es posible efectuar pruebas serológicas