SAGA1 and SAGA2 promote starch formation around proto-pyrenoids in Arabidopsis chloroplasts.

The pyrenoid is a chloroplastic microcompartment in which most algae and some terrestrial plants condense the primary carboxylase, Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) as part of a CO2-concentrating mechanism that improves the efficiency of CO2 capture. Engineering a pyrenoid-based CO2-concentrating mechanism (pCCM) into C3 crop plants is a promising strategy to enhance yield capacities and resilience to the changing climate. Many pyrenoids are characterized by a sheath of starch plates that is proposed to act as a barrier to limit CO2 diffusion. Recently, we have reconstituted a phase-separated "proto-pyrenoid" Rubisco matrix in the model C3 plant Arabidopsis thaliana using proteins from the alga with the most well-studied pyrenoid, Chlamydomonas reinhardtii [N. Atkinson, Y. Mao, K. X. Chan, A. J. McCormick, Nat. Commun. 11, 6303 (2020)]. Here, we describe the impact of introducing the Chlamydomonas proteins StArch Granules Abnormal 1 (SAGA1) and SAGA2, which are associated with the regulation of pyrenoid starch biogenesis and morphology. We show that SAGA1 localizes to the proto-pyrenoid in engineered Arabidopsis plants, which results in the formation of atypical spherical starch granules enclosed within the proto-pyrenoid condensate and adjacent plate-like granules that partially cover the condensate, but without modifying the total amount of chloroplastic starch accrued. Additional expression of SAGA2 further increases the proportion of starch synthesized as adjacent plate-like granules that fully encircle the proto-pyrenoid. Our findings pave the way to assembling a diffusion barrier as part of a functional pCCM in vascular plants, while also advancing our understanding of the roles of SAGA1 and SAGA2 in starch sheath formation and broadening the avenues for engineering starch morphology.

Cement-a-TAN Temporary Proximal Femoral Replacement for Staged Joint Replacement - A Case Report.

INTRODUCTION: Infected non-unions of proximal femoral fractures are difficult to treat. If debridement and revision fixation is unsuccessful, staged revision arthroplasty may be required. Non-viable tissue must be resected; coupled with the introduction of an antibiotic-eluting temporary spacer before definitive reconstruction. Tissue microbiological diagnosis and targeted antibiotic therapy are required. In cases of significant proximal femoral bone loss, spacing options are limited. CASE REPORT: We present a case of a bisphosphonate-induced subtrochanteric fracture that progressed to infected non-union. Despite multiple washouts and two revision fixations, the infection remained active with an unfavorable antibiogram. The patient required staged revision arthroplasty including a proximal femoral resection. To improve function through maintaining leg length and offset, the Cement-a-TAN was fabricated. It is a custom-made antibiotic-eluting articulating temporary spacer. Using a trochanteric entry cephalocondylar nail as a scaffold, bone cement was molded around the nail to fashion an anatomical and patient-specific proximal femoral spacer. Following resolution of the infection, the Cement-a-TAN was removed and a proximal femoral arthroplasty was successfully performed. CONCLUSION: Cement-a-TAN is an excellent temporary spacing technique in staged proximal femoral replacement for infected non-union of the proximal femur where there has been significant bone loss. It preserves mobility and maintains leg length, offset, and periarticular soft-tissue tension, while offering good stability.

Investigation of the in vitro antimicrobial activity of triclosan-coated suture material on bacteria commonly isolated from wounds in dogs.

OBJECTIVE: To investigate in vitro effects of triclosan coating of suture materials on the growth of clinically relevant bacteria isolated from wounds in dogs. SAMPLE: 6 types of suture material and 10 isolates each of methicillin-susceptible Staphylococcus pseudintermedius, methicillin-resistant S pseudintermedius, Escherichia coli, and AmpC ß-lactamase and extended-spectrum ß-lactamase-producing E coli from clinical wound infections. PROCEDURES: Isolates were cultured on Mueller-Hinton agar with 3 types of triclosan-coated suture, uncoated counterparts of the same suture types, and positive and negative controls. Zones of inhibition (ZOIs) were measured after overnight incubation. Sustained antimicrobial activity assays were performed with susceptible isolates. The ZOI measurements and durations of sustained antimicrobial activity were compared among suture types and isolates by statistical methods. Suture surface characteristics and bacterial adherence were evaluated qualitatively with scanning electron microscopy. RESULTS: ZOIs were generated only by triclosan-coated materials; triclosan-coated suture had sustained antimicrobial activity (inhibition) for 3 to 29 days against all tested pathogens. The ZOIs around triclosan-coated suture were significantly greater for S pseudintermedius isolates than for E coli isolates. Bacterial adherence to uncoated polyglactin-910 was greatest, followed by triclosan-coated polyglactin-910, and then uncoated monofilament sutures, with least adherence to coated monofilament sutures. CONCLUSIONS AND CLINICAL RELEVANCE: Surface characteristics of suture materials may be as important or more important than triclosan coating for microbial inhibition; however, triclosan coating appeared to affect bacterial adherence for multifilament sutures. Triclosan-coated, particularly monofilament, sutures inhibited pathogens commonly isolated from wounds of dogs, including multidrug-resistant bacteria. Further studies are required to assess clinical efficacy of triclosan-coated suture materials in vivo.

One health education for future physicians in the pan-epidemic "Age of Humans".

We propose the term "pan-epidemic Anthropocene" to refer to multifocal infectious disease epidemics related to human-caused (anthropogenic) forces such as urbanization, globalization, industrialization and the growing populations of humans and animals. The integrated framework of One Health (human, animal, and environmental health) helps both to understand why epidemics occur when and where they do, and also how to respond, mitigate, and sometimes prevent them. We suggest a collaborative mechanism for increasing One Health in medical education to create a synergy of strengths between the growing number of contributing One Health organizations in the US and internationally.

Retrograde femoral nailing of periprosthetic fractures around total knee replacements.

INTRODUCTION: The incidence of primary total knee replacement (TKR) is increasing with a resultant rise in those patients sustaining distal femoral periprosthetic fractures around TKRs. The management of these fractures pose a significant challenge. The compatibility of retrograde femoral intramedullary (IM) nails with femoral TKR components needs to be considered preoperatively when this complex pathology is addressed. The aim of this study was to update the literature and assess the compatibility of the most commonly used primary TKR prostheses and retrograde femoral IM nails using a Sawbone anatomical model. METHODS AND MATERIALS: Eight of the most commonly used primary TKR prostheses and four of the most commonly used retrograde femoral IM nails were identified. The femoral components of the TKRs were implanted onto left sided femoral Sawbones using the manufacturer's guides and cutting blocks and positioned appropriately. The retrograde IM nails were inserted using the conventional entry point and a nail was deemed compatible if this was possible through the femoral prosthesis. Details of whether a posterior entry point was required to allow insertion, whether the femoral nail was scratched by the femoral TKR prosthesis on insertion and whether excess force was required to insert the retrograde femoral IM nail were recorded. RESULTS: The Biomet AGC Cruciate Retaining (CR) and Posterior Stabilised (PS) TKR were the only prostheses that were compatible with all the nails used. The other TKR prostheses were not compatible because of the force required to gain entry, scratching of the retrograde femoral IM nail or because a posterior entry point was required to gain entry through the intercondylar notch. CONCLUSION: The majority of standard sized retrograde femoral nails are technically feasible for insertion through most femoral TKR components but this study has found that they are not compatible due to excessive force required for insertion, damage to the nail during insertion or the risk of anterior cortex perforation. Further studies are required to update the compatibility table and cadaveric studies would confirm the findings and allow further mechanical testing.

Forest fuel reduction alters fire severity and long-term carbon storage in three Pacific Northwest ecosystems.

Two forest management objectives being debated in the context of federally managed landscapes in the U.S. Pacific Northwest involve a perceived trade-off between fire restoration and carbon sequestration. The former strategy would reduce fuel (and therefore C) that has accumulated through a century of fire suppression and exclusion which has led to extreme fire risk in some areas. The latter strategy would manage forests for enhanced C sequestration as a method of reducing atmospheric CO2 and associated threats from global climate change. We explored the trade-off between these two strategies by employing a forest ecosystem simulation model, STANDCARB, to examine the effects of fuel reduction on fire severity and the resulting long-term C dynamics among three Pacific Northwest ecosystems: the east Cascades ponderosa pine forests, the west Cascades western hemlock-Douglas-fir forests, and the Coast Range western hemlock-Sitka spruce forests. Our simulations indicate that fuel reduction treatments in these ecosystems consistently reduced fire severity. However, reducing the fraction by which C is lost in a wildfire requires the removal of a much greater amount of C, since most of the C stored in forest biomass (stem wood, branches, coarse woody debris) remains unconsumed even by high-severity wildfires. For this reason, all of the fuel reduction treatments simulated for the west Cascades and Coast Range ecosystems as well as most of the treatments simulated for the east Cascades resulted in a reduced mean stand C storage. One suggested method of compensating for such losses in C storage is to utilize C harvested in fuel reduction treatments as biofuels. Our analysis indicates that this will not be an effective strategy in the west Cascades and Coast Range over the next 100 years. We suggest that forest management plans aimed solely at ameliorating increases in atmospheric CO2 should forgo fuel reduction treatments in these ecosystems, with the possible exception of some east Cascades ponderosa pine stands with uncharacteristic levels of understory fuel accumulation. Balancing a demand for maximal landscape C storage with the demand for reduced wildfire severity will likely require treatments to be applied strategically throughout the landscape rather than indiscriminately treating all stands.