Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 62
Filtrar
1.
Trauma Case Rep ; 51: 100999, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38550962

RESUMO

We describe a trifocal femur injury with intracapsular femoral neck fracture, diaphyseal fracture with bone loss, and distal complete articular (AO/OTA C type) fracture, an injury rarely described in the literature. Surgical management utilized a not-yet-reported implant combination: screw-side plate device for the intracapsular femoral neck, retrograde nail for the diaphysis, and lag screws plus mini fragment buttress plating for the distal fracture. The patient had uneventful fracture union with no changes in alignment. Given the rarity and complexity of this injury, there is little consensus on surgical technique and implant choice. This case demonstrates a modernized approach that may be useful for surgeons who encounter similar fracture patterns in their practice.

2.
J Orthop Res ; 42(2): 249-258, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-37990953

RESUMO

Musculoskeletal trauma, specifically fractures, is a leading cause of patient morbidity and disability worldwide. In approximately 20% of cases with fracture and related traumatic muscle loss, bone healing is impaired leading to fracture nonunion. Over the past few years, several studies have demonstrated that bone and the surrounding muscle tissue interact not only anatomically and mechanically but also through biochemical pathways and mediators. Severe damage to the surrounding musculature at the fracture site causes an insufficiency in muscle-derived osteoprogenitor cells that are crucial for fracture healing. As an endocrine tissue, skeletal muscle produces many myokines that act on different bone cells, such as osteoblasts, osteoclasts, osteocytes, and mesenchymal stem cells. Investigating how muscle influences fracture healing at cellular, molecular, and hormonal levels provides translational therapeutic solutions to this clinical challenge. This review provides an overview about the contributions of surrounding muscle tissue in directing fracture healing. The focus of the review is on describing the interactions between bone and muscle in both healthy and fractured environments. We discuss current progress in identifying the bone-muscle molecular pathways and strategies to harness these pathways as cues for accelerating fracture healing. In addition, we review the existing challenges and research opportunities in the field.


Assuntos
Consolidação da Fratura , Fraturas Ósseas , Humanos , Consolidação da Fratura/fisiologia , Osso e Ossos , Músculo Esquelético/fisiologia , Osteoclastos
3.
Plant Physiol Biochem ; 202: 107959, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37619271

RESUMO

Antibacterial activity is a common and highly studied property of plant secondary metabolites. Despite the extensive literature focusing on identifying novel antibacterial metabolites, little work has been undertaken to examine variation in levels of antibacterial activity in any plant species. Here, we used large-scale sampling of leaves of the antibacterial plant, wild garlic (Allium ursinum L.), assembling a set of tissue extracts from 168 plants, with 504 leaves collected and analysed. We assayed extracts for antibacterial activity against Bacillus subtilis and used LC-MS to carry out a chemometric analysis examining variation in individual metabolites, comparing them with several ecological parameters. We found that allicin was the only metabolite which was positively related to antibacterial activity. Soil temperature was a key determinant of variability in the concentrations of many foliar metabolites, however, neither allicin concentrations nor antibacterial activity was related to any of our measured ecological parameters, other than roadside proximity. We suggest that the synthesis of allicin precursors may be largely independent of growing conditions. This may be to ensure that allicin is synthesised rapidly and in sufficiently high concentrations to effectively prevent herbivory and pest damage. This finding contrasts with flavonoids which were found to vary greatly between plants and across sites. Our findings suggest that key biologically active metabolites are constrained in their concentration range compared to other compounds in the metabolome. This has important implications for the development of wild garlic as a health supplement or animal feed additive.


Assuntos
Alho , Animais , Ração Animal , Antibacterianos/farmacologia , Bacillus subtilis
4.
Trauma Case Rep ; 45: 100836, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37200771

RESUMO

Case report: Traumatic hip dislocations require prompt diagnosis and reduction to preserve the native joint. The classic irreducible posterior hip fracture-dislocation has been described as an immobile, slightly flexed, and internally rotated hip on physical exam. Classically, this irreducible pattern is associated with an ipsilateral femoral head fracture. The purpose of our report is to present an irreducible posterior hip dislocation with preserved motion in the setting of an unstable pelvic ring injury without associated femoral head pathology. Despite lacking clinical features of an irreducible hip, closed reduction in the emergency and operating rooms was unsuccessful, even after frame application for pelvis stability. Persistent irreducibility necessitated open reduction, where the femoral head was found to be buttonholed through the posterior hip capsule and blocking reduction. Conclusion: A posteriorly dislocated hip with preserved motion in the setting of a concomitant unstable pelvic ring injury may belie the true locked nature of the femoroacetabular dislocation and high suspicion for femoral head incarceration is required. The description of this unique irreducible fracture pattern and the stepwise approach used for reduction may be useful for other surgeons who may encounter similar patterns of injury.

5.
J Clin Med ; 11(22)2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36431255

RESUMO

In order to determine the impact of COVID-19 on the treatment and outcomes in patients with proximal femoral fracture's (PFF), we analyzed a national US sample. This is a retrospective review of American College of Surgery's (ACS) National Surgical Quality Improvement Program (NSQIP) for patients with proximal femoral fractures. A total of 26,830 and 26,300 patients sustaining PFF and undergoing surgical treatment were sampled during 2019 and 2020, respectively. On multivariable logistic regression, patients were less likely to have 'presence of non-healing wound' (p < 0.001), functional status 'independent' (p = 0.012), undergo surgical procedures of 'hemiarthroplasty'(p = 0.002) and 'ORIF IT, Peritroch, Subtroch with plates and screws' (p < 0.001) and to be 'alive at 30-days post-op' (p = 0.001) in 2020 as compared to 2019. Patients were more likely to have a case status 'emergent', 'loss of ≥10% body weight', discharge destination of 'home' (p < 0.001 for each) or 'leaving against medical advice' (p = 0.026), postoperative 'acute renal failure (ARF)' (p = 0.011), 'myocardial infarction (MI)' (p = 0.006), 'pulmonary embolism (PE)' (p = 0.047), and 'deep venous thrombosis (DVT)' (p = 0.049) in 2020 as compared to 2019. Patients sustaining PFF and undergoing surgical treatment during pandemic year 2020 differed significantly in preoperative characteristics and 30-day postoperative complications when compared to patients from the previous year.

6.
Plast Reconstr Surg Glob Open ; 10(10): e4584, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36284720

RESUMO

An essential component in ambulatory breast augmentation surgery is good analgesia. The demographic undergoing this operation is usually fit, low risk with few comorbidities. These patients do not require long-term hospitalization and do not want to spend excessive time in the hospital for financial reasons. Opiate analgesia can have significant side effects such as nausea, vomiting, and sedation. Reducing volumes of postoperative opiates allows faster ambulation and discharge from day surgery. We have developed two targeted nerve blocks that the operating surgeon can apply in minutes under direct vision, not requiring imaging. Anecdotally, we found that these targeted nerve blocks reduced opiate requirements and allowed accelerated discharge and faster return to normal activities. We conducted a prospective randomized, double-blind trial to test this theory. Methods: Twenty patients were randomized into saline (n = 10) or ropivacaine adrenaline solution (n = 10). The operating surgeons and anesthetists were blinded to the solution. All patients were closely followed up, and morphine equivalents were accurately recorded. Follow-up pain scores were recorded using the Overall Benefit of Analgesia pain questionnaire. Results: The ropivacaine nerve blocks significantly reduced opiate requirements postoperatively (P < 0.05). Pain scores were significantly decreased in the study group (P < 0.05). There were no side effects attributable to the nerve blocks. Conclusion: Intraoperative targeted nerve blocks significantly reduce postoperative opiate requirements in breast augmentation surgery resulting in faster recovery and higher patient satisfaction.

7.
J Biol Inorg Chem ; 27(4-5): 485-495, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35796835

RESUMO

Most pathogenic bacteria require ferrous iron (Fe2+) in order to sustain infection within hosts. The ferrous iron transport (Feo) system is the most highly conserved prokaryotic transporter of Fe2+, but its mechanism remains to be fully characterized. Most Feo systems are composed of two proteins: FeoA, a soluble SH3-like accessory protein, and FeoB, a membrane protein that translocates Fe2+ across a lipid bilayer. Some bacterial feo operons encode FeoC, a third soluble, winged-helix protein that remains enigmatic in function. We previously demonstrated that selected FeoC proteins bind O2-sensitive [4Fe-4S] clusters via Cys residues, leading to the proposal that some FeoCs could sense O2 to regulate Fe2+ transport. However, not all FeoCs conserve these Cys residues, and FeoC from the causative agent of cholera (Vibrio cholerae) notably lacks any Cys residues, precluding cluster binding. In this work, we determined the NMR structure of VcFeoC, which is monomeric and conserves the helix-turn-helix domain seen in other FeoCs. In contrast, however, the structure of VcFeoC reveals a truncated winged ß-sheet in which the cluster-binding domain is notably absent. Using homology modeling, we predicted the structure of VcNFeoB and used docking to identify an interaction site with VcFeoC, which is confirmed by NMR spectroscopy. These findings provide the first atomic-level structure of VcFeoC and contribute to a better understanding of its role vis-à-vis FeoB.


Assuntos
Vibrio cholerae , Proteínas de Bactérias/química , Regulação Bacteriana da Expressão Gênica , Sequências Hélice-Volta-Hélice , Ferro/metabolismo , Óperon , Vibrio cholerae/genética , Vibrio cholerae/metabolismo
8.
Tissue Eng Part C Methods ; 28(6): 239-249, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35438548

RESUMO

Mesenchymal stromal cells (MSCs) from older donors have limited potential for bone tissue formation compared with cells from younger donors, and cellular senescence has been postulated as an underlying cause. There is a critical need for methods to induce premature senescence to study this phenomenon efficiently and reproducibly. However, the field lacks consensus on the appropriate method to induce and characterize senescence. Moreover, we have a limited understanding of the effects of commonly used induction methods on senescent phenotype. To address this significant challenge, we assessed the effect of replicative, hydrogen peroxide, etoposide, and irradiation-induced senescence on human MSCs using a battery of senescent cell characteristics. All methods arrested proliferation and resulted in increased cell spreading compared with low passage controls. Etoposide and irradiation increased expression of senescence-related genes in MSCs at early time points, proinflammatory cytokine secretion, DNA damage, and production of senescence-associated ß-galactosidase. We then evaluated the effect of fisetin, a flavonoid and candidate senolytic agent, to clear senescent cells and promote osteogenic differentiation of MSCs entrapped in gelatin methacryloyl (GelMA) hydrogels in vitro. When studying a mixture of nonsenescent and senescent MSCs, we did not observe decreases in senescent markers or increases in osteogenesis with fisetin treatment. However, the application of the same treatment toward a heterogeneous population of human bone marrow-derived cells entrapped in GelMA decreased senescent markers and increased osteogenesis after 14 days in culture. These results identify best practices for inducing prematurely senescent MSCs and motivate the need for further study of fisetin as a senolytic agent. Impact Statement The accumulation of senescent cells within the body has detrimental effects on tissue homeostasis. To study the role of senescent cells on tissue repair and regeneration, there is a need for effective means to induce premature cell senescence. Herein, we characterized the influence of common stressors to induce premature senescence in human mesenchymal stromal cells (MSCs). Irradiation of MSCs resulted in a phenotype most similar to quiescent, high-passage cells. These studies establish key biomarkers for evaluation when studying senescent cells in vitro.


Assuntos
Células-Tronco Mesenquimais , Osteogênese , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Senescência Celular/genética , Etoposídeo/metabolismo , Etoposídeo/farmacologia , Gelatina , Metacrilatos , Senoterapia
9.
Animals (Basel) ; 11(12)2021 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-34944360

RESUMO

Assessing the palatability of forage from locally adapted trees could improve the sustainability of livestock production systems. However, grasses continue to dominate livestock feed across the Amazon. We established a silvopastoral cattle farming system in Peru, comparing three different forage tree species with grass monocultures using a randomised block design. Trees were arranged in alleys of 0.5 × 7.5 m, planted alongside grass, and were directly browsed by cattle. Browse removal was estimated by three methods: destructive sampling, canopy measurements and leaf counts. We found that all three tree species were palatable to cattle. Plots containing trees and grass produced more available forage (mean > 2.2 Mg ha-1) for cattle than the grass monocultures (mean = 1.5 Mg ha-1). Destructive sampling below 1.6 m demonstrated that cattle consumed 99% of the available Erythrina berteroana forage, 75% of the available Inga edulis forage and 80% of the available Leucaena leucocephala forage in 8 days. This research demonstrates methodologies to estimate the intake of locally adapted browse species by cattle and highlights the potential benefits of silvopastoral systems in the Amazon. Planting trees could also benefit animal health and provide ecosystem services such as soil regeneration, enhanced nutrient cycling and carbon capture.

10.
Biochemistry ; 60(44): 3277-3291, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34670078

RESUMO

Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the export of this element require dedicated pathways that are dependent on oxidation state. Due to its solubility and kinetic lability, reduced ferrous iron (Fe2+) is useful to bacteria for import, chaperoning, and efflux. Once imported, ferrous iron may be loaded into apo and nascent enzymes and even sequestered into storage proteins under certain conditions. However, excess labile ferrous iron can impart toxicity as it may spuriously catalyze Fenton chemistry, thereby generating reactive oxygen species and leading to cellular damage. In response, it is becoming increasingly evident that bacteria have evolved Fe2+ efflux pumps to deal with conditions of ferrous iron excess and to prevent intracellular oxidative stress. In this work, we highlight recent structural and mechanistic advancements in our understanding of prokaryotic ferrous iron import and export systems, with a focus on the connection of these essential transport systems to pathogenesis. Given the connection of these pathways to the virulence of many increasingly antibiotic resistant bacterial strains, a greater understanding of the mechanistic details of ferrous iron cycling in pathogens could illuminate new pathways for future therapeutic developments.


Assuntos
Bactérias/metabolismo , Ferro/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Antibacterianos/metabolismo , Transporte Biológico , Catálise , Homeostase , Transporte de Íons , Cinética , Proteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras/fisiologia , Oxirredução , Estresse Oxidativo , Células Procarióticas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Solubilidade , Virulência
11.
Oecologia ; 195(1): 213-223, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33458802

RESUMO

Plant and animal community composition changes at higher elevations on mountains. Plant and animal species richness generally declines with elevation, but the shape of the relationship differs between taxa. There are several proposed mechanisms, including the productivity hypotheses; that declines in available plant biomass confers fewer resources to consumers, thus supporting fewer species. We investigated resource availability as we ascended three aspects of Helvellyn mountain, UK, measuring several plant nutritive metrics, plant species richness and biomass. We observed a linear decline in plant species richness as we ascended the mountain but there was a unimodal relationship between plant biomass and elevation. Generally, the highest biomass values at mid-elevations were associated with the lowest nutritive values, except mineral contents which declined with elevation. Intra-specific and inter-specific increases in nutritive values nearer the top and bottom of the mountain indicated that physiological, phenological and compositional mechanisms may have played a role. The shape of the relationship between resource availability and elevation was different depending on the metric. Many consumers actively select or avoid plants based on their nutritive values and the abundances of consumer taxa vary in their relationships with elevation. Consideration of multiple nutritive metrics and of the nutritional requirements of the consumer may provide a greater understanding of changes to plant and animal communities at higher elevations. We propose a novel hypothesis for explaining elevational diversity gradients, which warrants further study; the 'nutritional complexity hypothesis', where consumer species coexist due to greater variation in the nutritional chemistry of plants.


Assuntos
Biodiversidade , Ecossistema , Altitude , Animais , Benchmarking , Biomassa
12.
J Orthop Trauma ; 35(8): e293-e297, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-33252444

RESUMO

OBJECTIVES: To compare piriformis fossa to greater trochanteric entry cephalomedullary implants in an evaluation of femoral neck load to failure when the device is used for femoral shaft fractures with prophylaxis of an associated femoral neck fracture. METHODS: Thirty fourth-generation synthetic femur models were separated into 5 groups: intact femora, entry sites alone at the piriformis fossa or greater trochanter, and piriformis fossa and greater trochanteric entry sites after the insertion of a cephalomedullary nail. Each model was mechanically loaded with a flat plate against the superior femoral head along the mechanical axis and load to failure was recorded. RESULTS: Mean load to failure was 5487 ± 376 N in the intact femur, 3126 ± 387 N in the piriformis fossa entry site group, 3772 ± 558 N in the piriformis entry nail, 5332 ± 292 N for the greater trochanteric entry site, and 5406 ± 801 N for the greater trochanteric nail group. Both piriformis groups were significantly lower compared with the intact group. Both greater trochanteric groups were similar to the intact group and were statistically higher than the piriformis groups. CONCLUSIONS: A piriformis fossa entry site with or without an intramedullary implant weakens the femoral neck in load to failure testing. A greater trochanteric entry yields a load to failure equivalent to that of an intact femoral neck. Instrumentation with a greater trochanteric cephalomedullary nail is significantly stronger than a piriformis fossa cephalomedullary nail during axial loading in a composite femur model.


Assuntos
Fraturas do Fêmur , Fraturas do Colo Femoral , Fixação Intramedular de Fraturas , Pinos Ortopédicos , Fêmur , Humanos , Unhas
13.
OTA Int ; 4(2 Suppl)2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37608854

RESUMO

Fracture healing is a complex cascade of cellular and molecular processes. These processes require the appropriate cellular and molecular environment to ensure the restoration of skeletal stability and resolution of inflammation. In order for fracture healing to occur, the necessary building blocks for bone metabolism and synthesis must be supplied through proper nutrition. Pharmacologic therapies aimed at modulating the inflammatory response to fractures have the potential to interfere with the synthesis of molecules needed for the production of bone. Infection can interfere with, and even prevent normal fracture healing from occurring. Cellular and genetic treatment strategies are actively being developed to target deficiencies, and bridge gaps that can influence how fractures heal. Evolving technologies, including nutritional supplementation, pharmacotherapies, antibiotics, surgical techniques, as well as genetic and cellular therapies, have the potential to enhance, optimize, and even revolutionize the process of fracture healing.

14.
15.
Clin Cancer Res ; 26(18): 4767-4776, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32611648

RESUMO

PURPOSE: Preclinical studies show that adavosertib, a WEE1 kinase inhibitor, sensitizes TP53-mutant cells to chemotherapy. We hypothesized that adavosertib, plus chemotherapy, would enhance efficacy versus placebo in TP53-mutated ovarian cancer. PATIENTS AND METHODS: Following safety run-in, this double-blind phase II trial (NCT01357161) randomized women with TP53-mutated, platinum-sensitive ovarian cancer to oral adavosertib (225 mg twice daily for 2.5 days/21-day cycle) or placebo, plus carboplatin (AUC5) and paclitaxel (175 mg/m2), until disease progression or for six cycles. The primary endpoints were progression-free survival (PFS) by enhanced RECIST v1.1 [ePFS (volumetric)] and safety. Secondary/exploratory objectives included PFS by RECIST v1.1 (single dimension), objective response rate, overall survival, and analysis of tumor gene profile versus sensitivity to adavosertib. RESULTS: A total of 121 patients were randomized to adavosertib (A+C; n = 59) and placebo (P+C; n = 62) plus chemotherapy. Adding adavosertib to chemotherapy improved ePFS [median, 7.9 (95% confidence interval (CI), 6.9-9.9) vs. 7.3 months (5.6-8.2); HR 0.63 (95% CI, 0.38-1.06); two-sided P = 0.080], meeting the predefined significance threshold (P < 0.2). Clinical benefit was observed following A+C for patients with different TP53 mutation subtypes, identifying possible response biomarkers. An increase in adverse events was seen with A+C versus P+C: greatest for diarrhea (adavosertib 75%; placebo 37%), vomiting (63%; 27%), anemia (53%; 32%), and all grade ≥3 adverse events (78%; 65%). CONCLUSIONS: Establishing an optimal strategy for managing tolerability and identifying specific patient populations most likely to benefit from treatment may increase clinical benefit. Future studies should consider additional adavosertib doses within the chemotherapy treatment cycle and the potential for maintenance therapy.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Biomarcadores Tumorais/genética , Neoplasias Ovarianas/tratamento farmacológico , Proteína Supressora de Tumor p53/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Carboplatina/administração & dosagem , Carboplatina/efeitos adversos , Método Duplo-Cego , Feminino , Humanos , Pessoa de Meia-Idade , Mutação , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/mortalidade , Paclitaxel/administração & dosagem , Paclitaxel/efeitos adversos , Intervalo Livre de Progressão , Pirazóis/administração & dosagem , Pirazóis/efeitos adversos , Pirimidinonas/administração & dosagem , Pirimidinonas/efeitos adversos , Critérios de Avaliação de Resposta em Tumores Sólidos
16.
Bone ; 125: 151-159, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31102712

RESUMO

Local muscle loss associated with open fractures remains an obstacle to functional recovery and bone healing. Muscle cells secrete bioactive myokines that elicit autocrine and paracrine effects and initiate signaling pathways for regenerating damaged muscle and bone. Mesenchymal stem/stromal cells (MSCs) are under investigation for the regeneration of both muscle and bone through their potent secretome. Compared to monodisperse cells, MSC spheroids exhibit a more complex secretome with heightened therapeutic potential. We hypothesized that the osteogenic potential of myokines would be enhanced when myoblasts were exposed to the MSC spheroid secretome. Conditioned media from MSC spheroids increased osteogenic response of MC3T3 pre-osteoblasts compared to myokines from L6 myoblasts alone. This effect was synergistically enhanced when conditioned media of MSC spheroids was serially delivered to myoblasts and then osteoprogenitor cells in vitro. We then delivered myoblast-stimulated conditioned media in the presence or absence of syngeneic rat bone marrow stromal cells (rBMSCs) from alginate hydrogels to a rat critical-sized segmental defect. We observed increased bone formation in defects treated with conditioned media compared to rBMSCs alone, while bone formation was greatest in defects treated with both conditioned media and rBMSCs over 12 weeks. This foundational study demonstrates a novel approach for capitalizing on the paracrine signaling of muscle cells to promote bone repair and provides additional evidence of the synergistic interaction between muscle and bone.


Assuntos
Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Mioblastos/efeitos dos fármacos , Mioblastos/metabolismo , Animais , Densidade Óssea/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Meios de Cultivo Condicionados/farmacologia , Humanos , Hidrogéis/química , Camundongos , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Osteogênese/efeitos dos fármacos , Ratos , Esferoides Celulares/efeitos dos fármacos , Esferoides Celulares/metabolismo
17.
J Orthop Trauma ; 33 Suppl 6: S12-S19, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31083143

RESUMO

Tissue engineering in orthopaedic trauma is needed. Progress has been made in all areas including regenerating bone, cartilage, soft tissue, and making up for bone defects with scaffolds. Bone regeneration and managing bone defects with scaffolds continue to be successful in the basic science realm with promising results, but currently, these successes are mostly limited to small animal models. Cartilage defects have more clinically available treatment options, but the benefits of "off-the-shelf" allograft options, and scaffolds, have little clinical evidence in the acute fracture setting. Most of the true chondrocyte replacement therapies such as matrix-induced autologous chondrocyte implantation and osteochondral allografts require delayed treatment while cell growth or graft matching occurs. Soft-tissue defects can be managed with tissue engineering for the skin with success, but muscle and nerve defects are still limited to the basic science arena. Although significant gains have been made in all areas for tissue engineering in basic science, and is very promising, this success currently comes with limited translation into clinical availability for the orthopaedic trauma patient.


Assuntos
Regeneração Óssea , Ortopedia/métodos , Engenharia Tecidual/métodos , Ferimentos e Lesões/terapia , Animais , Humanos , Tecidos Suporte
18.
Injury ; 50(3): 703-707, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30384972

RESUMO

OBJECTIVES: Prophylactic femoral neck fixation may be performed in the setting of geriatric diaphyseal femur fracture, pathologic or impending atypical femur fractures. Fixation constructs often utilize cephalomedullary implants with one or two proximal interlocking screws into the femoral head/neck. Variations in proximal femoral anatomy and implant design can interfere with the placement of two screws in the femoral head and neck. Our objective was to assess the strength of piriformis entry reconstruction implants with one versus two proximal interlock screws for prophylactic femoral neck fixation. METHODS: Thirty fourth generation synthetic femur models were separated into 5 groups. The control group was an intact femur, and the second group was an intact femur with an entry hole in the piriformis fossa. The remaining groups had an intramedullary nail placed with either 0, 1, or 2 screws placed into the femoral head and neck. Each femur was mechanically loaded along the mechanical axis through the femoral head. Load to failure and failure displacement were recorded. RESULTS: Mean load to failure was 5583 ± 543 N in the intact femur. Constructs with 2 screws had a significantly higher mean load to failure (3223 ± 474 N) compared to one screw constructs (2368 ± 280 N). All of the experimental groups remained significantly lower than the intact femur model (p < 0.05). CONCLUSION: Our results demonstrate that piriformis entry reconstruction implants have a significantly lower load to failure compared to an intact femur irrespective of screw construct. Further studies are needed to investigate this potential iatrogenic weakening.


Assuntos
Órgãos Artificiais , Fraturas do Colo Femoral/cirurgia , Colo do Fêmur , Fixação Intramedular de Fraturas/instrumentação , Fenômenos Biomecânicos , Parafusos Ósseos , Força Compressiva , Desenho de Equipamento , Colo do Fêmur/cirurgia , Humanos , Teste de Materiais , Modelos Biológicos , Suporte de Carga
19.
Stem Cells ; 36(9): 1393-1403, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29968952

RESUMO

Cell-based approaches for musculoskeletal tissue repair are limited by poor cell survival and engraftment. Short-term hypoxic preconditioning of mesenchymal stem cells (MSCs) can prolong cell viability in vivo, while the aggregation of MSCs into spheroids increases cell survival, trophic factor secretion, and tissue formation in vivo. We hypothesized that preconditioning MSCs in hypoxic culture before spheroid formation would increase cell viability, proangiogenic potential, and resultant bone repair compared with that of individual MSCs. Human MSCs were preconditioned in 1% O2 in monolayer culture for 3 days (PC3) or kept in ambient air (PC0), formed into spheroids of increasing cell density, and then entrapped in alginate hydrogels. Hypoxia-preconditioned MSC spheroids were more resistant to apoptosis than ambient air controls and this response correlated with duration of hypoxia exposure. Spheroids of the highest cell density exhibited the greatest osteogenic potential in vitro and vascular endothelial growth factor (VEGF) secretion was greatest in PC3 spheroids. PC3 spheroids were then transplanted into rat critical-sized femoral segmental defects to evaluate their potential for bone healing. Spheroid-containing gels induced significantly more bone healing compared with gels containing preconditioned individual MSCs or acellular gels. These data demonstrate that hypoxic preconditioning represents a simple approach for enhancing the therapeutic potential of MSC spheroids when used for bone healing. Stem Cells 2018;36:1393-1403.


Assuntos
Hipóxia Celular/fisiologia , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Esferoides Celulares/citologia , Esferoides Celulares/metabolismo , Animais , Osso e Ossos/citologia , Osso e Ossos/metabolismo , Técnicas de Cultura de Células , Humanos , Masculino , Ratos
20.
J Plant Res ; 131(4): 641-654, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29550895

RESUMO

Forage plants are valuable because they maintain wild and domesticated herbivores, and sustain the delivery of meat, milk and other commodities. Forage plants contain different quantities of fibre, lignin, minerals and protein, and vary in the proportion of their tissue that can be digested by herbivores. These nutritive components are important determinants of consumer growth rates, reproductive success and behaviour. A dataset was compiled to quantify variation in forage plant nutritive values within- and between-plant species, and to assess variation between plant functional groups and bioclimatic zones. 1255 geo-located records containing 3774 measurements of nutritive values for 136 forage plant species grown in 30 countries were obtained from published articles. Spatial variability in forage nutritive values indicated that climate modified plant nutritive values. Forage plants grown in arid and equatorial regions generally contained less digestible material than those grown in temperate and tundra regions; containing more fibre and lignin, and less protein. These patterns may reveal why herbivore body sizes, digestion and migration strategies are different in warmer and drier regions. This dataset also revealed the capacity for variation in the nutrition provided by forage plants, which may drive consumer species coexistence. The proportion of the plant tissue that was digestible ranged between species from 2 to 91%. The amount of fibre contained within plant material ranged by 23-90%, protein by 2-36%, lignin by 1-21% and minerals by 2-22%. On average, grasses and tree foliage contained the most fibre, whilst herbaceous legumes contained the most protein and tree foliage contained the most lignin. However, there were individual species within each functional group that were highly nutritious. This dataset may be used to identify forage plant species or mixtures of species from different functional groups with useful nutritional traits which can be cultivated to enhance livestock productivity and inform wild herbivore conservation strategies.


Assuntos
Ração Animal , Meio Ambiente , Valor Nutritivo , Animais , Clima , Geografia , Herbivoria , Gado/metabolismo , Proteínas de Plantas/metabolismo , Poaceae
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...