Reference genes for gene expression analysis in the fungal pathogen Neonectria ditissima and their use demonstrating expression up-regulation of candidate virulence genes.

European canker, caused by the necrotrophic fungal phytopathogen Neonectria ditissima, is one of the most damaging apple diseases worldwide. An understanding of the molecular basis of N. ditissima virulence is currently lacking. Identification of genes with an up-regulation of expression during infection, which are therefore probably involved in virulence, is a first step towards this understanding. Reverse transcription quantitative real-time PCR (RT-qPCR) can be used to identify these candidate virulence genes, but relies on the use of reference genes for relative gene expression data normalisation. However, no report that addresses selecting appropriate fungal reference genes for use in the N. ditissima-apple pathosystem has been published to date. In this study, eight N. ditissima genes were selected as candidate RT-qPCR reference genes for gene expression analysis. A subset of the primers (six) designed to amplify regions from these genes were specific for N. ditissima, failing to amplify PCR products with template from other fungal pathogens present in the apple orchard. The efficiency of amplification of these six primer sets was satisfactory, ranging from 81.8 to 107.53%. Analysis of expression stability when a highly pathogenic N. ditissima isolate was cultured under 10 regimes, using the statistical algorithms geNorm, NormFinder and BestKeeper, indicated that actin and myo-inositol-1-phosphate synthase (mips), or their combination, could be utilised as the most suitable reference genes for normalisation of N. ditissima gene expression. As a test case, these reference genes were used to study expression of three candidate virulence genes during a time course of infection. All three, which shared traits with fungal effector genes, had up-regulated expression in planta compared to in vitro with expression peaking between five and six weeks post inoculation (wpi). Thus, these three genes may well be involved in N. ditissima pathogenicity and are priority candidates for further functional characterization.

Design and demonstration of ultra-compact microcell concentrating photovoltaics for space.

Optical concentration can improve the efficiency and reduce the cost of photovoltaic power but has traditionally been too bulky, massive, and unreliable for use in space. Here, we explore a new ultra-compact and low-mass microcell concentrating photovoltaic (µCPV) paradigm for space based on the monolithic integration of transfer-printed microscale solar cells and molded microconcentrator optics. We derive basic bounds on the compactness as a function of geometric concentration ratio and angular acceptance, and show that a simple reflective parabolic concentrator provides the best combination of specific power, angular acceptance, and overall fabrication simplicity. This architecture is simulated in detail and validated experimentally with a µCPV prototype that is less than 1.7 mm thick and operates with six, 650 µm square triple-junction microcells at a geometric concentration ratio of 18.4×. In outdoor testing, the system achieves a terrestrial power conversion efficiency of 25.8 ± 0.2% over a ±9.5° angular range, resulting in a specific power of approximately 111 W/kg. These results lay the groundwork for future space µCPV systems and establish a realistic path to exceed 350 W/kg specific power at >33% power conversion efficiency by scaling down to even smaller microcells.

Solution processes for ultrabroadband and omnidirectional graded-index glass lenses with near-zero reflectivity in high concentration photovoltaics.

Concentrator photovoltaic (CPV) systems, where incident direct solar radiation is tightly concentrated onto high-efficiency multi-junction solar cells by geometric optical elements, exhibit the highest efficiencies in converting the sun's energy into electric power. Their energy conversion efficiencies are greatly limited, however, due to Fresnel reflection losses occurring at three air/optics interfaces in the most sophisticated dual-stage CPV platforms. This paper describes a facile one-step wet-etching process to create a nanoporous surface with a graded-index profile on both flat and curved glasses, with capabilities of achieving ~99% average transmission efficiency in a wide wavelength range from 380 nm to 1.3 µm and for a wide range of incident angles up to ±40° regardless of the polarization state of incident sunlight. The simplicity of the etching process remarkably increases their versatility in various optical elements that require unconventional form factors such as Fresnel lenses and microlens arrays, and/or demanding curvatures along with much reduced dimensions such as ball lenses. Etched glass surfaces on two-stage optical concentrating systems yield enhancements in total optical transmission efficiencies by 13.8% and in the photocurrent by 14.3%, as experimentally determined by measurements on microscale triple-junction solar cells. The presented strategy can be widely adapted in a variety of applications such as image sensors, display systems, and other optoelectronic devices.

Concentrator photovoltaic module architectures with capabilities for capture and conversion of full global solar radiation.

Emerging classes of concentrator photovoltaic (CPV) modules reach efficiencies that are far greater than those of even the highest performance flat-plate PV technologies, with architectures that have the potential to provide the lowest cost of energy in locations with high direct normal irradiance (DNI). A disadvantage is their inability to effectively use diffuse sunlight, thereby constraining widespread geographic deployment and limiting performance even under the most favorable DNI conditions. This study introduces a module design that integrates capabilities in flat-plate PV directly with the most sophisticated CPV technologies, for capture of both direct and diffuse sunlight, thereby achieving efficiency in PV conversion of the global solar radiation. Specific examples of this scheme exploit commodity silicon (Si) cells integrated with two different CPV module designs, where they capture light that is not efficiently directed by the concentrator optics onto large-scale arrays of miniature multijunction (MJ) solar cells that use advanced III-V semiconductor technologies. In this CPV+ scheme ("+" denotes the addition of diffuse collector), the Si and MJ cells operate independently on indirect and direct solar radiation, respectively. On-sun experimental studies of CPV+ modules at latitudes of 35.9886° N (Durham, NC), 40.1125° N (Bondville, IL), and 38.9072° N (Washington, DC) show improvements in absolute module efficiencies of between 1.02% and 8.45% over values obtained using otherwise similar CPV modules, depending on weather conditions. These concepts have the potential to expand the geographic reach and improve the cost-effectiveness of the highest efficiency forms of PV power generation.

Printing-based assembly of quadruple-junction four-terminal microscale solar cells and their use in high-efficiency modules.

Expenses associated with shipping, installation, land, regulatory compliance and on-going maintenance and operations of utility-scale photovoltaics can be significantly reduced by increasing the power conversion efficiency of solar modules through improved materials, device designs and strategies for light management. Single-junction cells have performance constraints defined by their Shockley-Queisser limits. Multi-junction cells can achieve higher efficiencies, but epitaxial and current matching requirements between the single junctions in the devices hinder progress. Mechanical stacking of independent multi-junction cells circumvents these disadvantages. Here we present a fabrication approach for the realization of mechanically assembled multi-junction cells using materials and techniques compatible with large-scale manufacturing. The strategy involves printing-based stacking of microscale solar cells, sol-gel processes for interlayers with advanced optical, electrical and thermal properties, together with unusual packaging techniques, electrical matching networks, and compact ultrahigh-concentration optics. We demonstrate quadruple-junction, four-terminal solar cells with measured efficiencies of 43.9% at concentrations exceeding 1,000 suns, and modules with efficiencies of 36.5%.

Supplemental bio-tenodesis improves tibialis anterior allograft yield load in extremely low density tibiae.

INTRODUCTION: Improved soft tissue tendon graft mechanical properties have led to their increased use for anterior cruciate ligament (ACL) reconstruction. Because they do not have an osseous component; however, there are greater concerns regarding tibial graft slippage during early postoperative rehabilitation and activities of daily living, particularly in patients with poor bone mineral density (BMD), such as older patients, women, smokers, and patients undergoing revision ACL reconstruction surgery. METHODS: This in vitro biomechanical study attempted to determine the effectiveness of supplemental ACL graft fixation in low BMD tibiae. Eight paired knees (16 specimens) were harvested from female cadavers (mean age = 76, range = 60-88 years). Tibiae were assigned to either a combination bioabsorbable interference screw, bio-tenodesis screw group (Group 1, n = 8, apparent BMD = 0.44 ± 0.13 g/cm(2)) or a bioabsorbable interference screw group (Group 2, n = 8, apparent BMD = 0.44 ± 0.14 g/cm(2)). Double-strand (single loop) tibialis anterior tendon allografts were fixed in matched diameter tibial tunnels. Using a custom 6° of freedom jig, potted constructs were mounted on to a servo hydraulic device with the axial loading force aligned directly with the tibial tunnel. Constructs underwent progressive cyclic tensile loading from 10 to 150 N with a 25 N load increase every 20 cycles. This was followed by yield load to failure testing (20 mm/min). RESULTS: Groups did not display displacement differences during progressive cyclic loading. Group 1 (312.7 ± 67.5 N) displayed 25% greater yield load at failure than Group 2 (235.0 ± 47.6 N), P = 0.045. Both groups displayed fixation levels well below the previously reported minimal safe threshold estimate for early unrestricted weight bearing, accelerated rehabilitation and activities of daily living. CONCLUSION: Supplemental bio-tenodesis fixation may improve early tibial-soft tissue tendon graft fixation in patients that have poor tibial BMD, but study results suggest that both methods may require weightbearing, rehabilitation, and activity of daily living restrictions during the early postoperative period to prevent graft slippage.

The anterolateral incision for pilon fracture surgery: an anatomic study of cutaneous blood supply.

The purpose of this study was to examine the blood supply to the adjacent skin and its vulnerability to anterolateral tibial plating performed with fibular plating through a single surgical incision. Ten lightly embalmed cadaver legs without a history of lower extremity trauma or surgery with a mean age of 71 years (range, 57 to 87 years) were used for this investigation. Each specimen was injected with a commercially available silicone compound through the popliteal artery. The left leg was plated through a modified extensile Böhler approach and the right leg served as the control. Each leg was anatomically dissected. All measurements were taken using a digital caliper by a single investigator. A mean of 93 (range, 4 to 17) perforating arteries were present and in the proximity of the fibula plate. Our findings suggest the potential for iatrogenic soft tissue breakdown along the posterior border of the anterolateral surgical incision in this procedure as a result of compromised blood supply to the skin.

Compartment syndrome of the forearm: a systematic review.

In this systematic review, we examined the available evidence regarding compartment syndrome of the forearm. Applying our inclusion criteria, we found 12 articles for a total of 84 cases using the MEDLINE (Ovid) database. All were retrospective studies (level IV evidence). In this study, papers were analyzed for causes, diagnosis, treatment, methods of wound closure, functional outcome, and complications. The most common cause of compartment syndrome of the forearm in children was a supracondylar fracture, while in adults the most common cause was a fracture of the distal radius. The diagnostic criterion used was clinical assessment alone in 48%, and in 52%, a combination of measurement of intracompartmental pressure and clinical assessment was used. The intracompartmental pressure was measured using various techniques including a wick catheter, slit catheter, the Whitesides technique, and the Stryker compartment pressure measuring device. Fasciotomy was the preferred method of treatment (73%). In cases reporting wound management, postfasciotomy skin grafting was needed in 61% of the cases, whereas secondary closure was performed in 39% of the cases. Neurological deficit was the most common complication (21%).

The management of nonunion and delayed union of patella fractures: a systematic review of the literature.

Nonunion and delayed union of patella fractures are rare conditions that are fraught with challenges. There exists limited evidence in the literature to guide the clinician in the management of these complications. Therefore, the purpose of this study was to perform a systematic review of the available evidence on the management of nonunion and delayed union of patella fractures. A total of five publications which met our criteria were identified and formed the basis of this study. The decision making in the treatment of this condition is based on the functional demands of the patient, the factors that led to the development of the nonunion, the potential impact of the biomechanical effects of a total patellectomy, and the presence of an intact extensor mechanism of the knee for a later reconstructive procedure. Patients with low functional demands may be managed with nonoperative methods; however, those who perform heavy physical work or participate in sports usually require open reduction and internal fixation. Tension band wiring is the treatment of choice for patients suitable for a reconstructive procedure. Partial or total patellectomy is also an option for small distal fragments or an inability to satisfactorily perform internal fixation.

Medial patellofemoral ligament reconstruction for recurrent patellar dislocation: a systematic review including rehabilitation and return-to-sports efficacy.

PURPOSE: We systematically reviewed the evaluated efficacy of medial patellofemoral ligament (MPFL) reconstruction, rehabilitation, and patient outcomes for safely returning patients to sports. METHODS: We performed a literature search using the Ovid Medline database from 1950 to present, as well as the SportDiscus and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases. Only English-language studies that described MPFL reconstruction or repair, rehabilitation, and patient outcome information were included. Search terms were combinations of "MPFL repair," "MPFL reconstruction," "patellofemoral ligament," "patellar dislocation," "patient outcome," and "rehabilitation." Coleman Methodology Scores were used to evaluate research quality. RESULTS: A total of 21 studies (11 prospective and 10 retrospective) met our inclusion criteria, with a total of 488 patients (184 male and 304 female patients) and 510 knees contributing to this review. Most patients were female (62.3%), and the mean age at surgery was 23.4 years (range, 6 to 52 years). Semitendinosus autografts were most commonly used (n = 145 [28.4%]). Of all reported complications at follow-up (n = 155), quadriceps dysfunction (n = 48 [31.0%]), positive apprehension (n = 32 [20.6%]), and decreased knee range of motion (n = 28 [18.1%]) were most common. Although inclusion criteria required rehabilitation information, the level of description was generally limited to acute care rehabilitation, with insufficient progressive exercise descriptions. Coleman Methodology Scores (58.76 ± 8.6) indicated generally poor study methodologies. CONCLUSIONS: MPFL reconstruction and rehabilitation are likely to improve a patient's ability to perform activities of daily living. Poor study methodology including outcome surveys that lack either sensitivity or validity to measure the influence of patellofemoral joint dysfunction on sports participation, as well as limited exercise rehabilitation information, make it difficult to determine efficacy. Recommendations for improved outcome measurements and more comprehensive functional rehabilitation are provided. LEVEL OF EVIDENCE: Level IV, systematic review.

Tourniquet use and sickle cell hemoglobinopathy: how should we proceed?

The use of tourniquets for upper and lower extremity operative procedures is controversial in patients with sickle cell hemoglobinopathies. The authors used Ovid and MEDLINE®, PubMed, and CINAHL® to detect English-language reports of any surgical procedure where a tourniquet was used on a patient with sickle cell disease or trait. Four papers met the search criteria and were reviewed. These studies included 96 patients with hemoglobin SS, SC, and sickle cell trait (AS). The investigations differed in tourniquet type, perioperative care, operative procedure, and patient genotype distribution. Twelve of 96 sickle cell patients (12.5%) experienced postoperative complications (8 SS/SC and 4 AS) detailed in two of the four studies. Nonetheless, the available limited evidence suggests that with proper perioperative management and necessary precautions, tourniquets can be used with relative safety in most patients with sickle cell disease.

Osseous deficits after anterior cruciate ligament injury and reconstruction: a systematic literature review with suggestions to improve osseous homeostasis.

PURPOSE: This systematic review was performed to improve our understanding of the current evidence regarding the influence of anterior cruciate ligament (ACL) injury and reconstruction on involved lower extremity apparent bone mineral density, bone content, or bone area mass (bone integrity). METHODS: Two independent reviewers performed a Medline search from 1966 to January 2010 using the terms "anterior cruciate ligament" or "ACL" combined with "wound" or "injury" and "bone density" or "osteoporosis." Study inclusion criteria were English-language human studies. Reference sections of selected studies were also reviewed. RESULTS: Ten studies were identified that met our inclusion criteria. Eight studies performed ACL reconstruction with bone-patellar tendon-bone autografts and interference screw fixation. One study performed ACL reconstruction by use of Achilles tendon allografts with interference screw and staple fixation. Two ACL injury studies either did not involve ACL reconstruction or attempted primary repair with sutures. All studies reported varying levels of decreased bone mineral density, bone content, or bone area mass (bone integrity) at the involved lower extremity after ACL injury that did not return to premorbid levels even with ACL reconstruction and rehabilitation. Sites of reduced bone integrity included the proximal and distal femur, proximal tibia, patella, and calcaneus. Bone loss was increased with limited weight bearing and prolonged disuse or immobilization; however, significant improvements were not observed with accelerated rehabilitation. Some studies reported relations between Lysholm, Tegner, International Knee Documentation Committee survey, or function scores and bone integrity, whereas others reported no or poor relations. CONCLUSIONS: Involved lower extremity bone integrity is decreased after ACL injury. Current evidence suggests that premorbid bone integrity is not re-established after ACL reconstruction even when accelerated rehabilitation is performed. Recommendations to improve osseous homeostasis and bone health after ACL injury and reconstruction are provided.

Challenge to the charging model of semiconductor-nanocrystal fluorescence intermittency from off-state quantum yields and multiexciton blinking.

Semiconductor nanocrystals emit light intermittently; i.e., they "blink," under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core(shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10:1. These results directly contradict the predictions of the charging model.

The citizen physician: governance principles make the difference.

Until recently, medicine was one of the few areas in which an individual could practice a profession as a citizen member of the organization. However, in the last 15 years as dramatic reductions have occurred in outpatient reimbursement, physicians have moved from self-governing organizations with the rights of citizen participation to autocratic, centrally controlled organizations with little offered to physicians other than to provide high-quality manual labor. The principles of prosperity and choice espoused in The Federalist Papers are governance principles that can reestablish citizenship in medical groups no matter who owns them.

Update on rehabilitation following ACL reconstruction.

As anterior cruciate ligament (ACL) reconstruction has evolved to less invasive, more anatomical approaches, rehabilitation of the injured athlete has likewise become more progressive and innovative, with a sound understanding of graft and fixation strength and biologic healing-remodeling constraints. This review discusses these innovations including specific considerations before surgery, when planning rehabilitation timetables, and the importance of reestablishing nonimpaired active and passive knee range of motion and biarticular musculotendinous extensibility in positions of function. Concepts of self-efficacy or confidence and reestablishing the "athlete role" are also addressed. Since ACL injury and reinjury are largely related to the influence of structure-form-function on dynamic knee joint stability, the interrelationships between sensorimotor, neuromuscular, and conventional resistance training are also discussed. Although pivot shift "giving way" relates to function loss following ACL injury, anterior translational laxity often does not. Although there is growing evidence that progressive eccentric training may benefit the patient following ACL reconstruction, there is less evidence supporting the use of functional ACL knee braces. Of considerable importance is selecting and achieving a criteria-based progression to sports-specific training, reestablishing osseous homeostasis and improved bone density, blending open and closed kinetic chain exercises at the appropriate time period, and appreciating the influence of the trunk, upper extremities, and sports equipment use on knee loads. We believe that knee dysfunction and functional recovery should be considered from a local, regional, and global perspective. These concepts are consolidated into our approach to prepare patients for return to play including field testing and maintenance training.

Quantum dot-based multiplexed fluorescence resonance energy transfer.

We demonstrate the use of luminescent quantum dots (QDs) conjugated to dye-labeled protein acceptors for nonradiative energy transfer in a multiplexed format. Two configurations were explored: (1) a single color QD interacting with multiple distinct acceptors and (2) multiple donor populations interacting with one type of acceptor. In both cases, we showed that simultaneous energy transfer between donors and proximal acceptors can be measured. However, data analysis was simpler for the configuration where multiple QD donors are used in conjunction with one acceptor. Steady-state fluorescence results were corroborated by time-resolved measurements where selective shortening of QD lifetime was measured only for populations that were selectively engaged in nonradiative energy transfer.

Neurochemical investigations of dopamine neuronal systems in iron-regulatory protein 2 (IRP-2) knockout mice.

Abnormal iron accumulations are frequently observed in the brains of patients with Parkinson's disease and in normal aging. Iron metabolism is regulated in the CNS by iron regulatory proteins (IRP-1 and IRP-2). Mice engineered to lack IRP-2 develop abnormal motoric behaviors including tremors at rest, abnormal gait, and bradykinesia at middle to late age (18 to 24 months). To further characterize the dopamine (DA) systems of IRP-2 -/- mice, we harvested CNS tissue from age-matched wild type and IRP-2 -/- (16-19 months) and analyzed the protein levels of tyrosine hydroxylase (TH), dopamine transporter (DAT), vesicular monoamine transporter (VMAT2), and DA levels in dorsal striatum, ventral striatum (including the core and shell of nucleus accumbens), and midbrain. We further analyzed the phosphorylation of TH in striatum at serine 40, serine 31, and serine 19. In both dorsal and ventral striatum of IRP-2 knockout mice, there was a 20-25% loss of TH protein and accompanied by a approximately 50% increase in serine 40 phosphorylation above wild-type levels. No change in serine 31 phosphorylation was observed. In the ventral striatum, there was also a significant loss (approximately 40%) of DAT and VMAT2. Levels of DA were decreased (approximately 20%) in dorsal striatum, but turnover of DA was also elevated ( approximately 30%) in dorsal striatum of IRP-2 -/- mice. We conclude that iron misregulation associated with the loss of IRP-2 protein affects DA regulation in the striatum. However, the modest loss of DA and DA-regulating proteins does not reflect the pathology of PD or animal models of PD. Instead, these observations support that the IRP-2 -/- genotype may enable neurobiological events associated with aging.

Room-temperature ordered photon emission from multiexciton states in single CdSe core-shell nanocrystals.

We report room-temperature ordered multiphoton emission from multiexciton states of single CdSe(CdZnS) core(-shell) colloidal nanocrystals (NCs) that are synthesized by wet chemical methods. Spectrally and temporally resolved measurements of biexciton and triexciton emission from single NCs are also presented. A simple four level system models the results accurately and provides estimates for biexciton and triexciton radiative lifetimes and quantum yields.

Can luminescent quantum dots be efficient energy acceptors with organic dye donors?

We assessed the ability of luminescent quantum dots (QDs) to function as energy acceptors in fluorescence resonance energy transfer (FRET) assays, with organic dyes serving as donors. Either AlexaFluor 488 or Cy3 dye was attached to maltose binding protein (MBP) and used with various QD acceptors. Steady-state and time-resolved fluorescence measurements showed no apparent FRET from dye to QD. We attribute these observations to the dominance of a fast radiative decay rate of the donor excitation relative to a slow FRET decay rate. This is due to the long exciton lifetime of the acceptor compared to that of the dye, combined with substantial QD direct excitation.