Immobilization Times Research Articles

Length of Post-treatment Immobilization Following Medial Humeral Epicondyle Avulsion Fracture Predicts Return of Full Range of Motion

Medial epicondyle fractures of the distal humerus are common pediatric fractures, which are increasing in frequency among pediatric and adolescent athletes. Residual elbow stiffness is a feared complication of both surgical and non-operative treatment. The purpose of this study is to investigate the association of the relevant variables with the ability of patients to regain full elbow range of motion (FROM). Patients 8-18 years-old enrolled in the Medial Epicondyle Multicenter Outcomes (MEMO) prospective cohort with ≥3 mm of displacement and >1 year of follow-up data were included. Bilateral elbow range of motion (ROM), complications, length of immobilization following definitive treatment (surgical vs. non-operative), participation in formal physical or occupational therapy (PT/OT), and weeks from injury to treatment were recorded. The study cohort consisted of 202 patients (aged 12.7±2.3 years; 59% male). A greater proportion of surgically managed patients regained FROM compared to non-operatively managed patients (71% vs. 56%, P=0.05). Immobilization time was significantly shorter in surgical than non-operative patients (2.0 ±1.1 weeks vs. 3.0±1.2 weeks, P<0.001). In multivariable logistic regression analysis, only immobilization time was an independent predictor of regaining FROM (β=-0.353, P=0.02), which remained statistically significant while controlling for PT/OT (β=0.079, P=0.829) and treatment strategy (β=-0.375, P=0.35). While controlling for treatment strategy and whether a patient received PT/OT, each week of prolonged immobilization decreased the chance of regaining full ROM by 35%. This large multicenter cohort study found that of the variables studied, increased immobilization time was the only independent predictor of residual elbow stiffness following medial epicondyle fractures in children, independent of treatment strategy and receiving PT/OT. With surgical treatment often warranting shorter post-treatment immobilization times, surgery may provide an avenue for consistently regaining FROM when treating these fractures, even in the setting of concomitant dislocation. In cases of minimally displaced fractures, implementing protected early ROM in non-operative cases could be considered. However, when nonoperatively-treated patients in this study were analyzed separately, earlier mobilization was not associated with a protective effect against residual stiffness. Further prospective study into the nuances of surgical indications as well as nonoperative and postoperative immobilization and early motion strategies is therefore warranted.

Electric-field assisted silicon nanowire field effect transistor for the ultra-low concentration nucleic acid detection

Ultra-low concentration nucleic acid detection is crucial for disease diagnosis and prognosis. Silicon nanowire field-effect transistors (SiNW FETs) are promising due to their sensitivity, real-time capabilities, and compact design. A critical consideration for FETs is the reaction time required for nucleic acid diffusion to the detection surface, especially at low concentrations. This study utilizes polycrystalline silicon nanowire FETs (poly-SiNW FETs) as biosensors, employing a negative voltage on the liquid gate used for detection to create an electric field. This field accelerates nucleic acid diffusion towards the sensor surface to interact with immobilized probes. We adjusted the gate voltages and target solution injection flow rates to identify optimal parameters for nucleic acid detection and how the electrical field accelerates hybridization kinetics. We varied the probe immobilization times to show that higher ligand density accelerates the interaction with the immobilized probe. The study demonstrated stable diffusion of target DNA by combining FET with an electric field of −1 V and a slow injection flow rate, reducing the equilibrium time from 60 to 20 min. Additional improvement was achieved by enhancing probe immobilization density and applying an electric field, resulting in a faster probe-target hybridization reaction rate. These efforts significantly improved the signal to maintain superior performance and reduced the time required to reach equilibrium. This research pioneers using an external electric field to expedite detection time in field-effect transistors, demonstrating the potential for accelerated nucleic acid detection in nanowire FETs.

Novel immobilization method of Lactiplantibacillus plantarum in grains for dry food products.

This study aimed to assess the potential use of grains (amaranth, millet, and quinoa) as immobilizing matrices on the metabolic activity of Lactiplantibacillus plantarum and evaluate the viability of the probiotic immobilized in millet during simulated oro-gastrointestinal digestion (OGI) and storage. Firstly, different grains, sterilization and immobilization times were assessed. Secondly, Lp. plantarum was immobilized in millet and its viability and metabolic activity were assessed during non-refrigerated long-term storage and OGI. Metabolic activity was higher with 15 min. of grain sterilization and 72 h of immobilization. Lp. plantarum in millet showed the highest count. Millet grains were able to maintain the high population (>7 log CFU/g) and the metabolic activity of Lp. plantarum during up to 150 d of storage and conferred a protective effect on entrapped probiotic cells during OGI. Millet is a promising immobilizing matrix for the addition of probiotics in dry food products.

Biosensing of arsenic by whole-cell bacterial bioreporter immobilized on polycaprolactone (PCL) electrospun fiber

ABSTRACT In recent years, heavy metals derived from several anthropogenic sources have both direct and indirect detrimental effects on the health of the environment and living organisms. Whole-cell bioreporters (WCBs) that can be used to monitor the levels of heavy metals in drinking and natural spring waters are important. In this study, whole-cell arsenic bacterial bioreporters were immobilized using polycaprolactone (PCL) electrospun fibers as the support material. The aim is to determine the properties of this immobilized bioreporter system by evaluating its performance in arsenic detection. Within the scope of the study, different growth media and fiber immobilization times were tested to determine the parameters affecting the fluorescent signals emitted by the immobilized bioreporter system in the presence of two dominant forms of arsenic, namely arsenite (As(III)) and arsenate (As(V)). In addition, the sensitivity, selectivity, response time, and shelf-life of the developed bioreporter system were evaluated. As far as the literature is concerned, this is the first study to investigate the potential of using PCL-electrospun fiber-immobilized fluorescent bacterial bioreporter for arsenic detection. This study will open new avenues in environmental arsenic monitoring.

Evaluation of Anesthetic and Cardiorespiratory Effects after Intramuscular Administration of Three Different Doses of Telazol® in Common Marmosets (Callithrix jacchus).

Marmosets' small body size makes anesthesia challenging. Ideally, small volumes of drugs should be administered intramuscularly (i.m.). In addition, dose-dependent sedation and anesthesia are desirable properties for sedatives and anesthetics in marmosets. Telazol® (tiletamine and zolazepam) is highly concentrated, allowing the use of small injection volumes and dose-dependent sedation and anesthesia. A randomized, blinded study with crossover design in ten healthy adult common marmosets (Callithrix jacchus) was performed to evaluate the anesthetic and cardiorespiratory effects of three doses of i.m. Telazol® (respectively, 5, 10, and 15 mg/kg). Depth of anesthesia, cardiorespiratory effects, and induction, immobilization, and recovery times were determined. A significant difference was observed in immobilization time between 5 and 15 mg/kg of Telazol®. In addition, 15 mg/kg of Telazol® resulted in increased recovery times compared to 5 mg/kg. The cardiorespiratory effects during the first 45 min of immobilization were within clinically acceptable limits. The pedal withdrawal reflex was the best indicator of the anesthetic depth.

Immobilization and Hand Therapy After Carpometacarpal Arthroplasty: A Systematic Review

PurposeWe provide a systematic review of the current literature regarding best practices in postoperative care following carpometacarpal arthroplasty, and compare these findings to current practices via reported survey data.MethodsThe PubMed, Cochrane, Cumulative Index to Nursing and Allied Health Literature, Science Direct, and Google Scholar databases were searched for relevant studies. English-language articles were included that assessed any aspect of postoperative care, including the immobilization time or rehabilitation strategy. In addition, studies were included that surveyed surgeons and hand therapists on current practices regarding this topic. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020.ResultsThe initial search yielded 3,899 hits. Two systematic reviews were found, along with 5 studies that specifically tested the desired variables of the immobilization duration and type following carpometacarpal arthroplasty. Three relevant surveys were also found. Using the Oxford Centre for Evidence-Based Medicine Level of Evidence guidelines, we found moderate-quality evidence that (1) there is no additional benefit for extended cast immobilization (>6 weeks); and (2) a semirigid orthosis performs as well as a rigid orthosis. We found a lack of evidence regarding formal therapy versus no therapy, and a lack of evidence comparing therapy regimens. When analyzing the survey data, we found wide variation in practices among surgeons and therapists.ConclusionsLonger immobilization times (>6 weeks) and rigid orthotic devices provide no additional benefit over earlier immobilization and semirigid orthotic devices. There is a lack of evidence for the use of formal hand therapy or any specific rehabilitation protocol. Current practices in these areas vary widely among hand surgeons.Clinical relevancePractices following carpometacarpal arthroplasty are widely variable, and guidance has previously been lacking. This review compiles the most recent data, as well as identifies gaps in the literature for future studies.

Field-Effect Capacitors Decorated with Ligand-Stabilized Gold Nanoparticles: Modeling and Experiments

Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (C–V) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the C–V curves and the ConCap signals was also studied experimentally on Al–p-Si–SiO2 EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles.

MEDETOMIDINE-KETAMINE-MIDAZOLAM VERSUS MEDETOMIDINE-KETAMINE-BUTORPHANOL FOR IMMOBILIZATION OF RED KANGAROOS (OSPHRANTER RUFUS).

The objectives of this clinical study were to compare the effectiveness and safety of medetomidine-ketamine-midazolam (MKM) versus medetomidine-ketamine-butorphanol (MKB) for immobilization of captive red kangaroos (Osphranter rufus). Twenty red kangaroos were randomly immobilized for routine treatments using intramuscular injection of MKM (0.065 ± 0.004, 2.2 ± 0.3, and 0.12 ± 0.04 mg/kg, respectively) or MKB (0.070 ± 0.015, 2.3 ± 0.5, and 0.23 ± 0.05 mg/kg, respectively) (n = 10/group). Induction, immobilization, and recovery times were recorded; vital signs monitored; and quality of induction, immobilization, and recovery scored using a single-blinded design. Oxygen was not supplemented. For reversal, atipamezole at five times the medetomidine dosage was administered intramuscularly (both groups), and flumazenil (0.020 ± 0.003 mg/kg; MKM) or naltrexone (0.23 ± 0.05 mg/kg; MKB) were administered intravenously. Induction time was significantly shorter in the MKB group versus the MKM group (7:26 ± 04:22 and 11:54 ± 04:50 minutes, respectively). Induction quality in both groups was rated "excellent" and immobilization quality was "excellent" in MKM and "very good" in MKB. Heart rate was significantly lower and hemoglobin oxygen saturation (SpO2) was significantly higher in the MKM versus the MKB group. However, SpO2 < 90% occurred with both protocols. Following antagonists administration, recovery time and quality were 17:40 ± 08:33 minutes and "very good" in the MKM group, and 14:28 ± 05:27 minutes and "excellent" in the MKB group, respectively. Both protocols provided smooth induction, good immobilization, and generally quick recovery. MKB is recommended for shorter induction time. Oxygen supplementation should be available with both protocols.

Helicopter‐Based Chemical Immobilization of Mountain Goats in Coastal Alaska

ABSTRACTThe development, evaluation, and refinement of effective and humane capture methods for wildlife studies is important for increasing our capacity to understand and effectively manageand conserve wildlife populations. Carfentanil has been the primary agent used to chemically immobilize mountain goats (Oreamnos americanus) during the past 40 years. However, carfentanil is no longer commercially available for wildlife captures in North America. To investigate viable alternatives for mountain goat capture, we conducted field trials using thiafentanil to immobilize free‐ranging mountain goats via aerial darting methods; thiafentanil responses were then compared to a standard and widely used carfentanil dose. During June–October, 2005–2020, we immobilized mountain goats with either 2.4–3.0 mg carfentanil (n = 444) or 6.0–7.0 mg thiafentanil (n = 68) across a range of different field conditions at 6 different study sites in coastal Alaska. Induction and recovery times were more rapid (and subsequent immobilization times reduced) using thiafentanil compared to carfentanil. In most other respects, however, immobilization characteristics (i.e., body temperature, pulse rate, relative oxygen saturation) were virtually indistinguishable between individuals immobilized with carfentanil or thiafentanil. During typical immobilizations, mean rectal temperature increased 1.8° C, but increased as much as 3.0° C in some extreme cases. Administration of supplemental oxygen resulted in substantial, potentially clinically significant increases in peripheral capillary oxygen saturation, arterial oxygen, and pH in immobilized mountain goats. Our findings indicate that thiafentanil is an effective alternative to carfentanil for chemical immobilization of mountain goats and may offer some important advantages, particularly when immobilizing mountain goats and other species in difficult and potentially dangerous capture environments. © 2021 The Wildlife Society.

Factors associated with surgeon recommendation for additional cast immobilization of a CT-verified nondisplaced scaphoid waist fracture

IntroductionData from clinical trials suggest that CT-confirmed nondisplaced scaphoid waist fractures heal with less than the conventional 8–12 weeks of immobilization. Barriers to adopting shorter immobilization times in clinical practice may include a strong influence of fracture tenderness and radiographic appearance on decision-making. This study aimed to investigate (1) the degree to which surgeons use fracture tenderness and radiographic appearance of union, among other factors, to decide whether or not to recommend additional cast immobilization after 8 or 12 weeks of immobilization; (2) identify surgeon factors associated with the decision to continue cast immobilization after 8 or 12 weeks.Materials and methodsIn a survey-based study, 218 surgeons reviewed 16 patient scenarios of CT-confirmed nondisplaced waist fractures treated with cast immobilization for 8 or 12 weeks and recommended for or against additional cast immobilization. Clinical variables included patient sex, age, a description of radiographic fracture consolidation, fracture tenderness and duration of cast immobilization completed (8 versus 12 weeks). To assess the impact of clinical factors on recommendation to continue immobilization we calculated posterior probabilities and determined variable importance using a random forest algorithm. Multilevel logistic mixed regression analysis was used to identify surgeon characteristics associated with recommendation for additional cast immobilization.ResultsUnclear fracture healing on radiographs, fracture tenderness and 8 (versus 12) weeks of completed cast immobilization were the most important factors influencing surgeons’ decision to recommend continued cast immobilization. Women surgeons (OR 2.96; 95% CI 1.28–6.81, p = 0.011), surgeons not specialized in orthopedic trauma, hand and wrist or shoulder and elbow surgery (categorized as ‘other’) (OR 2.64; 95% CI 1.31–5.33, p = 0.007) and surgeons practicing in the United States (OR 6.53, 95% CI 2.18–19.52, p = 0.01 versus Europe) were more likely to recommend continued immobilization.ConclusionAdoption of shorter immobilization times for CT-confirmed nondisplaced scaphoid waist fractures may be hindered by surgeon attention to fracture tenderness and radiographic appearance.

Prospective Cohort Study to Investigate Factors Associated With Continued Immobilization of a Nondisplaced Scaphoid Waist Fracture

The decision to continue immobilization of a nondisplaced scaphoid waist fracture is often based on radiographic appearance (despite evidence that radiographs are unreliable and inaccurate for diagnosing scaphoid union 6-12 weeks after fracture) and fracture tenderness (even though it is influenced by cognitive biases on pain). This may result in unhelpful additional immobilization. We studied nondisplaced scaphoid waist fractures to determine the factors associated with (1) the surgeon's decision to continue cast or splint immobilization at the first visit when cast removal was being considered; (2) greater pain on examination; and (3) the surgeon's concern about radiographic consolidation. We prospectively included 46 patients with a nondisplaced scaphoid waist fracture treated nonoperatively. At the first visit when cast removal was considered - after an average of 6 weeks of immobilization - patients rated pain during 4 examination maneuvers. The treating surgeon assessed union on radiographs and decided whether to continue or discontinue immobilization. Patients completed measures of the following: (1) the degree to which pain limits activities (Patient-Reported Outcome Measure Interactive System [PROMIS] Pain Interference Computer Adaptive Test [CAT], Pain Self-Efficacy Questionnaire-2); (2) symptoms of depression (PROMIS Depression CAT); and (3) upper extremity function (PROMIS Upper Extremity Function CAT). We used multivariable regression analysis to investigate the factors associated with each outcome. Perceived inadequate radiographic healing and greater symptoms of depression were independently associated with continued immobilization. Pain during the examination was not associated with continued immobilization. Patient age was associated with pain on examination. Shorter immobilization duration was the only factor associated with the surgeon's perception of inadequate radiographic consolidation. Inadequate radiographic healing and greater symptoms of depression are associated with a surgeon's decision to continue cast or splint immobilization of a nondisplaced scaphoid waist fracture. Overreliance on radiographs and inadequate accounting for psychological distress may hinder the adoption of shorter immobilization times for nondisplaced waist fractures.

Suture tape augmentation improves laxity of MCL repair in the ACL reconstructed knee.

Medial collateral ligament (MCL) injury is very common and surgical repair is sometimes necessary. Especially in the setting of simultaneous anterior cruciate ligament reconstruction (ACLR) as the ACL is the secondary restraint against valgus stress. The goal of this study was to evaluate knee biomechanics after suture repair of the MCL augmented with suture tape, as compared to MCL repair alone, in the setting of concomitant ACL reconstruction (ACLR). Fifteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under four loadings: (a) an 89.0N anterior tibial load, (b) a 5.0Nm internal and external rotation torque, (c) a 10.0Nm valgus load, (d) a 7.0Nm valgus load combined with 5.0Nm internal rotation torque as a static simulated pivot-shift. The tested conditions were ACLR with the following states: (1) MCL intact, (2) MCL deficient, (3) MCL Repair, and (4) MCL repair augmented with suture tape (MCL Repair + ST). Under the different knee loadings, the tibial displacement, and the force in either the intact MCL, suture repaired MCL or repaired MCL-suture tape complex was measured. While neither the MCL Repair nor the MCL Repair + ST restored valgus rotation to the MCL intact state, displacement was significantly smaller after MCL Repair + ST (p < 0.05). The knee rotation under external rotation torque in MCL Repair + ST did not differ MCL intact (n.s.), while with MCL Repair the rotation was significantly greater (p < 0.05). MCL Repair + ST did not cause an over-constraint of the knee in any of the tested loading conditions. In a combined ACL-reconstruction-MCL-repair model, MCL Repair augmented with suture tape improved valgus and external rotation laxity when compared to MCL suture repair alone. Suture tape augmentation may provide this additional means of stabilization and can be added at the time of surgical repair of the MCL. Clinically this may result in lower failure rates and less residual laxity after MCL repair, as well as shorter immobilization times and faster return to play.

Most surgeons still prefer to reduce overriding distal radius fractures in children

Background and purpose — Traditionally, overriding distal radius fractures in children have been reduced and immobilized with a cast or treated with percutaneous pin fixation. There is recent evidence that these fractures heal well if immobilized in the bayonet position without reduction. We evaluated the present treatment of these fractures. Methods — A questionnaire including AP and lateral radiographs of overriding distal radius fractures in 3 pre-pubertal children was answered by 213 surgeons from 28 countries. The surgeons were asked to choose their preferred method of treatment (no reduction, reduction, reduction and osteosynthesis), type and length of cast immobilization, and the number of clinical and radiographic follow-ups. Results — Of the 213 participating surgeons, 176 (83%) would have reduced all 3 presented fractures, whereas 4 (2%) would have treated all 3 children with cast immobilization without reduction. Most reductions (77%) would have been done under general anesthesia. Over half (54%) of the surgeons who preferred anesthesia would have fixed (pins 99%, plate 1%) the fractures. An above-elbow splint or circular cast was chosen in 84% of responses, and the most popular (44%) length of immobilization was 4 weeks. Surgeons from the Nordic countries were more eager to fix the fractures (54% vs. 31%, p < 0.001) and preferred shorter immobilization and follow-up times and less frequent clinical and radiological follow-ups compared with their colleagues from the USA. Interpretation — Most of the participating surgeons prefer to reduce overriding distal radius fractures in children under anesthesia. There is substantial lack of agreement on the indications for osteosynthesis, type of cast, length of immobilization, and follow-up protocol.

Field Chemical Immobilization of Free-Ranging Crested Porcupines with Zoletil®: A Reviewed Dosage.

The tiletamine-zolazepam mixture is a widely used anesthetic for chemical immobilization of wild mammals due to its short induction time, good muscle relaxation, smooth recovery with low convulsions occurrence, and minimal effect on respiration. An injection dose of 7–8 mg/kg of tiletamine-zolazepam has been proven to be an effective and safe immobilizing mixture for crested porcupines under field conditions. However, the occurrence of long immobilization and recovery times, with high excitement and convulsion during awakening, were recorded. In order to reduce such side effects after recovery, the effectiveness of a lower dosage (4–6 mg/kg) of tiletamine-zolazepam (Zoletil®) was tested. The results obtained confirm that the use of tiletamine-zolazepam in crested porcupine immobilization provides a quick induction, wide safety margin, and predictable awakening under field conditions. A smaller injection dosage of 5 mg/kg has been proven to be sufficient to ensure a short induction time (average: 7.1 min), with good muscle relaxation and little excitement of the animals during awakening. The lower dosage of tiletamine-zolazepam, while providing a shorter recovery time (average: 53.6 min), proves to be adequate for standard handling procedures. Furthermore, the smaller amount of tiletamine-zolazepam also ensures safe immobilization for pregnant individuals and porcupettes.

Current practices in the management of anterior glenohumeral instability in rugby union players

BackgroundRugby has the highest incidence of traumatic injuries of any sport, and glenohumeral injuries result in the lengthy delay in return to play. The purpose of this study is to survey surgeons from the American Shoulder and Elbow Surgeons (ASES), and the British Elbow and Shoulder Society (BESS) to evaluate the current state of management of anterior glenohumeral instability, and compare the differences in practices. MethodsA survey of surgeons from ASES and BESS was conducted. Treatment options were proposed in a variety of clinical scenarios of glenohumeral instability. The time of immobilization post-operatively, return to play, and attitudes on current contact regulations. Results were compared using the chi-square test or t-test. ResultsNinety-seven surgeons responded to the survey. There was a significant difference in treatment between ASES and BESS surgeons in the setting of primary dislocation (p < 0.05), but not recurrent dislocation (p > 0.05). The period of immobilization following injury and surgery was different between both treating groups. There was a significant difference in return to play between ASES and BESS surgeons with arthroscopic stabilization and open Bankart repair (p < 0.05), but not following conservative treatment or the Latarjet procedure (p > 0.05). ConclusionsThere remains wide variance on the management of glenohumeral instability in rugby union players among surgeons. While immobilization times post-operatively were similar, the BESS surgeons were more confident in allowing earlier return to play. There is also a significant concern that contact levels should be regulated to protect player safety. Level of evidenceLevel 4 (case series).

Experimental assessment of trophic ecology in a generalist spider predator: Implications for biocontrol in Uruguayan crops

AbstractConservative biological control promotes the use of native natural enemies to limit the size and growth of pest populations. Although spiders constitute one of the most important groups of native predators in several crops, their trophic ecology remains largely unknown, especially for several generalist taxa. In laboratory, we assessed the predatory behaviour of a wandering spider (the wolf spider Lycosa thorelli (Keyserling, 1877) against several arthropods varying in size and trophic positions, all found in South American soybean and rice crops. As prey we used the bug Piezodorus guildinii (Westwood, 1837) as well as larvae and adults of the moth Spodoptera frugiperda (Smith, 1797), both being considered important pests in Uruguayan crops. We also used several non‐pest arthropods as prey, sarcophagid flies, carabid beetles and wolf spiders. All prey were attacked in more or less high, although not statistically differing, proportions. However, carabids were not consumed, and bugs were consumed in significantly lower proportions than flies. A negative correlation was found between prey size and acceptance rate. Immobilization times were longer against larvae when compared to moths and flies, while predatory sequences were longer for bugs when compared to flies, moths and spiders. In addition, we found a positive effect of prey size on predatory sequence length and complexity. Our results confirm the ability of spiders to attack and feed upon prey with different morphologies, included well‐defended arthropods, and their potential use as natural enemies of several pests in South American crops.

Polyethylene glycol-mediated blocking and monolayer morphology of an electrochemical aptasensor for malaria biomarker detection in human serum

Better approaches are critically needed for in situ point-of-care diagnostic biosensors that enable primary care physicians, or even individual patients, to directly analyze biological fluids without complicated sample pretreatments. Additional purification steps consume time, consume reagents, often require other equipment, and can introduce false-negative results. Biosensors have been modified with blocking molecules to reduce biofouling; however, the effectiveness relies on their chemical composition and morphology. Here, we used a polyethylene glycol film to suppress unspecific binding from human serum on an electrochemical malaria aptasensor. A detailed study of the variation of the chemical and morphological composition of the aptamer/polyethylene glycol mixed monolayer as a function of incubation time was conducted. Higher resistance to matrix biofouling was found for polyethylene glycol than for hydrophobic alkanethiol films. The best sensor performance was observed for intermediate polyethylene glycol immobilization times. With prolonged incubation, phase separation of aptamer, and polyethylene glycol molecules locally increased the aptamer density and thereby diminished the analyte binding capability. Remarkably, polyethylene glycols do not affect the aptasensor sensitivity but enhance the complex matrix tolerance, the dynamic range, and the limit of detection. Careful tuning of the blocking molecule immobilization is crucial to achieving high aptasensor performance and biofouling resistance.

Glyoxyl-Activated Agarose as Support for Covalently Link Novo-Pro D: Biocatalysts Performance in the Hydrolysis of Casein

This study aimed to evaluate the performance of a commercial protease (Novo-Pro D (NPD)), both in soluble and immobilized forms, in the hydrolysis of proteins (using casein as model protein). Immobilization of the protease NPD on 6% agarose activated with glyoxyl groups for 24 h at 20 °C and pH 10.0 allowed preparing immobilized biocatalyst with around 90% immobilization yield, 92% recovered activity versus small substrate, and a thermal stability 5.3-fold higher than the dialyzed soluble enzyme at 50 °C and pH 8.0. Immobilization times longer than 24 h lead to a decrease in the recovered activity and did not improve the biocatalyst stability. At 50 °C and pH 6.5, the immobilized NPD was around 20-fold more stable than the dialyzed soluble protease. Versus casein, the immobilized NDP presented a 10% level of activity, but it allowed hydrolyzing casein (26 g/L) at 50 °C and pH 6.5 up to a 40% degree of hydrolysis (DH) after 2 h reaction, while under the same conditions, only a 34% DH was achieved with soluble NPD. In addition, the immobilized NPD showed good reusability, maintaining the DH of casein for at least ten 2h-reaction batches.

Comparison of two protocols for field immobilization of white-eared opossums (Didelphis albiventris)

Fil: Waxman Dova, Samanta. Universidad de Buenos Aires. Facultad de Cs.veterinarias. Catedra de Anestesiologia y Algiologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Predatory Versatility in Females of the Scorpion Bothriurus bonariensis (Scorpiones: Bothriuridae): Overcoming Prey with Different Defensive Mechanisms

Scorpions are dominant predators in some environments. Nevertheless, most studies of predatory behavior in scorpions have focused on diet composition whereas some other relevant aspects, such as predatory strategy, have been poorly explored. Herein we evaluate the prey acceptance and predatory strategy of the scorpion Bothriurus bonariensis against sympatric prey with different defenses. As prey, we selected earwigs (Forficula cf. auricularia) which use pincer-like defensive appendages, hard-bodied isopods (Armadillium vulgare) known for their conglobation defensive strategy, soft bodied isopods (Porcellio cf. scaber), which secrete noxious substances as defense mechanisms, cockroaches with limited defensive mechanisms (Blatta cf. orientalis.) and spiders (Lycosa cf. poliostoma) which possess venomous fangs. Prey were offered to 21 adults of B. bonariensis in random order until all prey had been offered to all scorpions. Prey consumption and the number of attempts needed for capture were recorded. We also evaluated the effect of sting use on immobilization time as well as the prey capture strategies on the most consumed prey. We found that despite using a similar number of attempts for capturing all prey, spiders and armadillid isopods were less consumed than other prey. Immobilization times were longer for earwigs than for armadillid isopods and cockroaches. Scorpions used alternative predatory strategies against these aforementioned prey, although the stinger was used against all of them. These results show that scorpions are able to use different predatory strategies which might allow them to include prey with diverse defensive strategies in their diet.