Experimental comparison of direct and indirect aptamer-based biochemical functionalization of electrolyte-gated graphene field-effect transistors for biosensing applications.

Aptamer-based electrolyte-gated graphene field-effect transistor (EGFET) biosensors have gained considerable attention because of their rapidity and accuracy in terms of quantification of a wide range of biomarkers. Functionalization of the graphene channel of EGFETs with aptamer biorecognition elements (BREs) is a crucial step in fabrication of EGFET aptasensors. This paper presents a comprehensive comparison of commonly used biochemical functionalization approaches applied for preparation of sensing films in EGFET aptasensors, namely indirect and direct immobilization of BREs. This study is the first of its kind to experimentally compare the two BREs immobilization approaches in terms of their effects on the carrier mobility of the monolayer graphene channel and their suitability for sensing applications. Both approaches can preserve and even improve the carrier mobility of bare graphene channel and hence the sensitivity of the EGFET; however, the direct BREs immobilization method was selected to develop an aptameric EGFET biosensor as this method enables simpler and more efficient preparation of the graphene-based aptameric sensing film. The utility of the prepared EGFET aptasensor is demonstrated through detection of tumor necrosis factor-α (TNF-α), an important inflammatory biomarker. The direct BREs immobilization approach is applied to develop an EGFET aptasensor to measure TNF-α in a detection range from 10 pg/ml to 10 ng/ml, representative of its physiological level in human sweat, as a non-invasively accessible biofluid. The outstanding sensing performance of the developed TNF-α EGFET aptasensor based on direct BREs immobilization can pave the way for development of graphene biosensors.

Prevalence and Diversity of Antibiotic Resistant Escherichia coli From Anthropogenic-Impacted Larut River.

Aquatic environments, under frequent anthropogenic pressure, could serve as reservoirs that provide an ideal condition for the acquisition and dissemination of antibiotic resistance genetic determinants. We investigated the prevalence and diversity of antibiotic-resistant Escherichia coli by focusing on their genetic diversity, virulence, and resistance genes in anthropogenic-impacted Larut River. The abundance of E. coli ranged from (estimated count) Est 1 to 4.7 × 105 (colony-forming units per 100 ml) CFU 100 ml-1 to Est 1 to 4.1 × 105 CFU 100 ml-1 with phylogenetic group B1 (46.72%), and A (34.39%) being the most predominant. The prevalence of multiple antibiotic resistance phenotypes of E. coli, with the presence of tet and sul resistance genes, was higher in wastewater effluents than in the river waters. These findings suggested that E. coli could be an important carrier of the resistance genes in freshwater river environments. The phylogenetic composition of E. coli and resistance genes was associated with physicochemical properties and antibiotic residues. These findings indicated that the anthropogenic inputs exerted an effect on the E. coli phylogroup composition, diversification of multiple antibiotic resistance phenotypes, and the distribution of resistance genes in the Larut River.

A predictable all-digital workflow to retrofit a crown to an existing removable prosthesis.

The task of fabricating a new crown under an existing removable partial denture presents challenges for the dentist, technician, and patient. The main concern is accurately communicating the configuration of the rest, retentive clasps, and reciprocal elements to the laboratory technician without temporarily depriving the patient of the prosthesis. A variety of solutions involving stone cast alterations and elastomeric or resin indexes have been used for this task. However, these methods require significant additional time and technique-sensitive work by the operator and technician. More recent approaches using digital technologies require many of these traditional steps, each of which introduces potential inaccuracy and labor cost. This updated approach eliminates the inaccuracies associated with manual manipulation by the technician by leveraging contemporary intraoral scanning technology and a completely digital workflow to predictably and accurately fabricate a crown under an existing prosthesis.

Defining the critical-sized defect in a rat segmental mandibulectomy model.

IMPORTANCE: Advances in tissue engineering offer potential alternatives to current mandibular reconstructive techniques; however, before clinical translation of this technology, a relevant animal model must be used to validate possible interventions. OBJECTIVE: To establish the critical-sized segmental mandibular defect that does not heal spontaneously in the rat mandible. DESIGN AND SETTING: Prospective study of mandibular defect healing in 29 Sprague-Dawley rats in an animal laboratory. INTERVENTIONS: The rats underwent creation of 1 of 4 segmental mandibular defects measuring 0, 1, 3, and 5 mm. All mandibular wounds were internally fixated with 1-mm microplates and screws and allowed to heal for 12 weeks, after which the animals were killed humanely. MAIN OUTCOMES AND MEASURES: Analysis with micro-computed tomography of bony union and formation graded on semiquantitative scales. RESULTS: Seven animals were included in each experimental group. No 5-mm segmental defects successfully developed bony union, whereas all 0- and 1-mm defects had continuous bony growth across the original defect on micro-computed tomography. Three of the 3-mm defects had bony continuity, and 3 had no healing of the bony wound. Bone union scores were significantly lower for the 5-mm defects compared with the 0-, 1-, and 3-mm defects (P < .01). CONCLUSIONS AND RELEVANCE: The rat segmental mandible model cannot heal a 5-mm segmental mandibular defect. Successful healing of 0-, 1-, and 3-mm defects confirms adequate stabilization of bony wounds with internal fixation with 1-mm microplates. The rat segmental mandibular critical-sized defect provides a clinically relevant testing ground for translatable mandibular tissue engineering efforts.

Bone morphogenetic protein-2-impregnated biomimetic scaffolds successfully induce bone healing in a marginal mandibular defect.

OBJECTIVES/HYPOTHESIS: To test the osteoregenerative potential and dosing of bone morphogenetic protein-2 (BMP-2)-impregnated biomimetic scaffolds in a rat model of a mandibular defect. STUDY DESIGN: Prospective study using an animal model. METHODS: Varied doses of BMP-2 (0.5, 1, 0.5, 0.5 in microspheres, 5, and 15 µg) were absorbed onto a biomimetic scaffold. Scaffolds were then implanted into marginal mandibular defects in rats. Blank scaffolds and unfilled defects were used as negative controls. Two months postoperatively, bone healing was analyzed with microcomputerized tomography (microCT). RESULTS: MicroCT analysis demonstrated that all doses of BMP-2 induced successful healing of marginal mandibular defects in a rat mandible. Increasing doses of BMP-2 on the scaffolds produced increased tissue healing, with 15 µg demonstrating significantly more healing than all other dosing (P < .01). CONCLUSIONS: BMP-2-impregnated biomimetic scaffolds successfully induce bone healing in a marginal mandibular defect in the rat. Percentage healing of defect, percentage of bone within healed tissue, and total bone volume are all a function of BMP-2 dosing. There appears to be an optimal dose of 5 µg beyond which there is no increase in bone volume. LEVEL OF EVIDENCE: NA.

Jones fractures in the elite football player.

The Jones fracture, defined as a proximal junctional metaphyseal/diaphyseal fracture of the fifth metatarsal, presents a challenge to the orthopaedic surgeon, especially in the competitive athlete. The purpose of this study is to characterize the Jones fracture in the elite athletic community and review the variety of treatments for these fractures in the National Football League (NFL). Between 1988 and 2002, 4758 elite collegiate football players participated in the NFL Combine. All athletes were evaluated clinically and radiographically. There were 86 Jones fractures identified in 83 athletes (incidence of 1.8%). Fifty-three percent (46 of 86) of the fractures were treated surgically. Eighty-nine percent (41 of 46) healed without complications and 7% (3 of 46) developed a nonunion. Twenty percent (8 of 40) of the fractures treated nonoperatively developed a nonunion while 80% (32 of 40) healed. The NFL injury surveillance system was also studied and revealed 17 Jones fractures occurred during the seasons 1996--2001. All of these fractures were treated with intramedullary screw fixation. The union rate was 94% (16 of 17 fractures). A questionnaire was also sent to all NFL team physicians regarding their experience with these fractures. The concensus was that this is not a common injury, but when it occurs, surgical treatment is recommended (77%) over nonsurgical treatment (23%). After reviewing the data, it was found that intramedullary screw fixation of Jones fractures is the treatment of choice for most physicians who treat elite collegiate and professional football athletes.