Alternating high-fat diet enhances atherosclerosis by neutrophil reprogramming.

Systemic immune responses caused by chronic hypercholesterolaemia contribute to atherosclerosis initiation, progression and complications1. However, individuals often change their dietary habits over time2, and the effects of an alternating high-fat diet (HFD) on atherosclerosis remain unclear. Here, to address this relevant issue, we developed a protocol using atherosclerosis-prone mice to compare an alternating versus continuous HFD while maintaining similar overall exposure periods. We found that an alternating HFD accelerated atherosclerosis in Ldlr-/- and Apoe-/- mice compared with a continuous HFD. This pro-atherogenic effect of the alternating HFD was also observed in Apoe-/-Rag2-/- mice lacking T, B and natural killer T cells, ruling out the role of the adaptive immune system in the observed phenotype. Discontinuing the HFD in the alternating HFD group downregulated RUNX13, promoting inflammatory signalling in bone marrow myeloid progenitors. After re-exposure to an HFD, these cells produced IL-1ß, leading to emergency myelopoiesis and increased neutrophil levels in blood. Neutrophils infiltrated plaques and released neutrophil extracellular traps, exacerbating atherosclerosis. Specific depletion of neutrophils or inhibition of IL-1ß pathways abolished emergency myelopoiesis and reversed the pro-atherogenic effects of the alternating HFD. This study highlights the role of IL-1ß-dependent neutrophil progenitor reprogramming in accelerated atherosclerosis induced by alternating HFD.

Further pharmacological and genetic evidence for the efficacy of PlGF inhibition in cancer and eye disease.

Our findings that PlGF is a cancer target and anti-PlGF is useful for anticancer treatment have been challenged by Bais et al. Here we take advantage of carcinogen-induced and transgenic tumor models as well as ocular neovascularization to report further evidence in support of our original findings of PlGF as a promising target for anticancer therapies. We present evidence for the efficacy of additional anti-PlGF antibodies and their ability to phenocopy genetic deficiency or silencing of PlGF in cancer and ocular disease but also show that not all anti-PlGF antibodies are effective. We also provide additional evidence for the specificity of our anti-PlGF antibody and experiments to suggest that anti-PlGF treatment will not be effective for all tumors and why. Further, we show that PlGF blockage inhibits vessel abnormalization rather than density in certain tumors while enhancing VEGF-targeted inhibition in ocular disease. Our findings warrant further testing of anti-PlGF therapies.

Robustness of DNA looping across multiple cell divisions in individual bacteria.

DNA looping has emerged as a central paradigm of transcriptional regulation, as it is shared across many living systems. One core property of DNA looping-based regulation is its ability to greatly enhance repression or activation of genes with only a few copies of transcriptional regulators. However, this property based on a small number of proteins raises the question of the robustness of such a mechanism with respect to the large intracellular perturbations taking place during growth and division of the cell. Here we address the issue of sensitivity to variations of intracellular parameters of gene regulation by DNA looping. We use the lac system as a prototype to experimentally identify the key features of the robustness of DNA looping in growing Escherichia coli cells. Surprisingly, we observe time intervals of tight repression spanning across division events, which can sometimes exceed 10 generations. Remarkably, the distribution of such long time intervals exhibits memoryless statistics that is mostly insensitive to repressor concentration, cell division events, and the number of distinct loops accessible to the system. By contrast, gene regulation becomes highly sensitive to these perturbations when DNA looping is absent. Using stochastic simulations, we propose that the observed robustness to division emerges from the competition between fast, multiple rebinding events of repressors and slow initiation rate of the RNA polymerase. We argue that fast rebinding events are a direct consequence of DNA looping that ensures robust gene repression across a range of intracellular perturbations.

All-or-none amyloid disassembly via chaperone-triggered fibril unzipping favors clearance of α-synuclein toxic species.

α-synuclein aggregation is present in Parkinson's disease and other neuropathologies. Among the assemblies that populate the amyloid formation process, oligomers and short fibrils are the most cytotoxic. The human Hsc70-based disaggregase system can resolve α-synuclein fibrils, but its ability to target other toxic assemblies has not been studied. Here, we show that this chaperone system preferentially disaggregates toxic oligomers and short fibrils, while its activity against large, less toxic amyloids is severely impaired. Biochemical and kinetic characterization of the disassembly process reveals that this behavior is the result of an all-or-none abrupt solubilization of individual aggregates. High-speed atomic force microscopy explicitly shows that disassembly starts with the destabilization of the tips and rapidly progresses to completion through protofilament unzipping and depolymerization without accumulation of harmful oligomeric intermediates. Our data provide molecular insights into the selective processing of toxic amyloids, which is critical to identify potential therapeutic targets against increasingly prevalent neurodegenerative disorders.

Endothelial Cell Indoleamine 2, 3-Dioxygenase 1 Alters Cardiac Function After Myocardial Infarction Through Kynurenine.

BACKGROUND: Ischemic cardiovascular diseases, particularly acute myocardial infarction (MI), is one of the leading causes of mortality worldwide. Indoleamine 2, 3-dioxygenase 1 (IDO) catalyzes 1 rate-limiting step of L-tryptophan metabolism, and emerges as an important regulator of many pathological conditions. We hypothesized that IDO could play a key role to locally regulate cardiac homeostasis after MI. METHODS: Cardiac repair was analyzed in mice harboring specific endothelial or smooth muscle cells or cardiomyocyte or myeloid cell deficiency of IDO and challenged with acute myocardial infarction. RESULTS: We show that kynurenine generation through IDO is markedly induced after MI in mice. Total genetic deletion or pharmacological inhibition of IDO limits cardiac injury and cardiac dysfunction after MI. Distinct loss of function of IDO in smooth muscle cells, inflammatory cells, or cardiomyocytes does not affect cardiac function and remodeling in infarcted mice. In sharp contrast, mice harboring endothelial cell-specific deletion of IDO show an improvement of cardiac function as well as cardiomyocyte contractility and reduction in adverse ventricular remodeling. In vivo kynurenine supplementation in IDO-deficient mice abrogates the protective effects of IDO deletion. Kynurenine precipitates cardiomyocyte apoptosis through reactive oxygen species production in an aryl hydrocarbon receptor-dependent mechanism. CONCLUSIONS: These data suggest that IDO could constitute a new therapeutic target during acute MI.

Dynamics of Cardiac Neutrophil Diversity in Murine Myocardial Infarction.

RATIONALE: After myocardial infarction, neutrophils rapidly and massively infiltrate the heart, where they promote both tissue healing and damage. OBJECTIVE: To characterize the dynamics of circulating and cardiac neutrophil diversity after infarction. METHODS AND RESULTS: We employed single-cell transcriptomics combined with cell surface epitope detection by sequencing to investigate temporal neutrophil diversity in the blood and heart after murine myocardial infarction. At day 1, 3, and 5 after infarction, cardiac Ly6G+ (lymphocyte antigen 6G) neutrophils could be delineated into 6 distinct clusters with specific time-dependent patterning and proportions. At day 1, neutrophils were characterized by a gene expression profile proximal to bone marrow neutrophils (Cd177, Lcn2, Fpr1), and putative activity of transcriptional regulators involved in hypoxic response (Hif1a) and emergency granulopoiesis (Cebpb). At 3 and 5 days, 2 major subsets of Siglecfhi (enriched for eg, Icam1 and Tnf) and Siglecflow (Slpi, Ifitm1) neutrophils were found. Cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) analysis in blood and heart revealed that while circulating neutrophils undergo a process of aging characterized by loss of surface CD62L and upregulation of Cxcr4, heart infiltrating neutrophils acquired a unique SiglecFhi signature. SiglecFhi neutrophils were absent from the bone marrow and spleen, indicating local acquisition of the SiglecFhi signature. Reducing the influx of blood neutrophils by anti-Ly6G treatment increased proportions of cardiac SiglecFhi neutrophils, suggesting accumulation of locally aged neutrophils. Computational analysis of ligand/receptor interactions revealed putative pathways mediating neutrophil to macrophage communication in the myocardium. Finally, SiglecFhi neutrophils were also found in atherosclerotic vessels, revealing that they arise across distinct contexts of cardiovascular inflammation. CONCLUSIONS: Altogether, our data provide a time-resolved census of neutrophil diversity and gene expression dynamics in the mouse blood and ischemic heart at the single-cell level, and reveal a process of local tissue specification of neutrophils in the ischemic heart characterized by the acquisition of a SiglecFhi signature.

Identification of Adipose Tissue as a Reservoir of Macrophages after Acute Myocardial Infarction.

Medullary and extra-medullary hematopoiesis has been shown to govern inflammatory cell infiltration and subsequently cardiac remodeling and function after acute myocardial infarction (MI). Emerging evidence positions adipose tissue (AT) as an alternative source of immune cell production. We, therefore, hypothesized that AT could act as a reservoir of inflammatory cells that participate in cardiac homeostasis after MI. To reveal the distinct role of inflammatory cells derived from AT or bone marrow (BM), chimeric mice were generated using standard repopulation assays. We showed that AMI increased the number of AT-derived macrophages in the cardiac tissue. These macrophages exhibit pro-inflammatory characteristics and their specific depletion improved cardiac function as well as decreased infarct size and interstitial fibrosis. We then reasoned that the alteration of AT-immune compartment in type 2 diabetes could, thus, contribute to defects in cardiac remodeling. However, in these conditions, myeloid cells recruited in the infarcted heart mainly originate from the BM, and AT was no longer used as a myeloid cell reservoir. Altogether, we showed here that a subpopulation of cardiac inflammatory macrophages emerges from myeloid cells of AT origin and plays a detrimental role in cardiac remodeling and function after MI. Diabetes abrogates the ability of AT-derived myeloid cells to populate the infarcted heart.

Iron Regulator Hepcidin Impairs Macrophage-Dependent Cardiac Repair After Injury.

BACKGROUND: Defective systemic and local iron metabolism correlates with cardiac disorders. Hepcidin, a master iron sensor, actively tunes iron trafficking. We hypothesized that hepcidin could play a key role to locally regulate cardiac homeostasis after acute myocardial infarction. METHODS: Cardiac repair was analyzed in mice harboring specific cardiomyocyte or myeloid cell deficiency of hepcidin and challenged with acute myocardial infarction. RESULTS: We found that the expression of hepcidin was elevated after acute myocardial infarction and the specific deletion of hepcidin in cardiomyocytes failed to improve cardiac repair and function. However, transplantation of bone marrow-derived cells from hepcidin-deficient mice ( Hamp-/-) or from mice with specific deletion of hepcidin in myeloid cells (LysMCRE/+/ Hampf/f) improved cardiac function. This effect was associated with a robust reduction in the infarct size and tissue fibrosis in addition to favoring cardiomyocyte renewal. Macrophages lacking hepcidin promoted cardiomyocyte proliferation in a prototypic model of apical resection-induced cardiac regeneration in neonatal mice. Interleukin (IL)-6 increased hepcidin levels in inflammatory macrophages. Hepcidin deficiency enhanced the number of CD45+/CD11b+/F4/80+/CD64+/MHCIILow/chemokine (C-C motif) receptor 2 (CCR2)+ inflammatory macrophages and fostered signal transducer and activator of transcription factor-3 (STAT3) phosphorylation, an instrumental step in the release of IL-4 and IL-13. The combined genetic suppression of hepcidin and IL-4/IL-13 in macrophages failed to improve cardiac function in both adult and neonatal injured hearts. CONCLUSIONS: Hepcidin refrains macrophage-induced cardiac repair and regeneration through modulation of IL-4/IL-13 pathways.

Genetic Depletion or Hyperresponsiveness of Natural Killer Cells Do Not Affect Atherosclerosis Development.

RATIONALE: Chronic inflammation is central in the development of atherosclerosis. Both innate and adaptive immunities are involved. Although several studies have evaluated the functions of natural killer (NK) cells in experimental animal models of atherosclerosis, it is not yet clear whether NK cells behave as protective or proatherogenic effectors. One of the main caveats of previous studies was the lack of specificity in targeting loss or gain of function of NK cells. OBJECTIVES: We used 2 selective genetic approaches to investigate the role of NK cells in atherosclerosis: (1) Ncr1iCre/+R26lsl-DTA/+ mice in which NK cells were depleted and (2) Noé mice in which NK cells are hyperresponsive. METHODS AND RESULTS: No difference in atherosclerotic lesion size was found in Ldlr-/- (low-density lipoprotein receptor null) mice transplanted with bone marrow (BM) cells from Ncr1iCreR26Rlsl-DTA , Noé, or wild-type mice. Also, no difference was observed in plaque composition in terms of collagen content, macrophage infiltration, or the immune profile, although Noé chimera had more IFN (interferon)-γ-producing NK cells, compared with wild-type mice. Then, we investigated the NK-cell selectivity of anti-asialoganglioside M1 antiserum, which was previously used to conclude the proatherogenicity of NK cells. Anti-asialoganglioside M1 treatment decreased atherosclerosis in both Ldlr-/- mice transplanted with Ncr1iCreR26Rlsl-DTA or wild-type bone marrow, indicating that its antiatherogenic effects are unrelated to NK-cell depletion, but to CD8+ T and NKT cells. Finally, to determine whether NK cells could contribute to the disease in conditions of pathological NK-cell overactivation, we treated irradiated Ldlr-/- mice reconstituted with either wild-type or Ncr1iCreR26Rlsl-DTA bone marrow with the viral mimic polyinosinic:polycytidylic acid and found a significant reduction of plaque size in NK-cell-deficient chimeric mice. CONCLUSIONS: Our findings, using state-of-the-art mouse models, demonstrate that NK cells have no direct effect on the natural development of hypercholesterolemia-induced atherosclerosis, but may play a role when an additional systemic NK-cell overactivation occurs.

Intra-Cardiac Release of Extracellular Vesicles Shapes Inflammation Following Myocardial Infarction.

RATIONALE: A rapid and massive influx of inflammatory cells occurs into ischemic area after myocardial infarction (MI), resulting in local release of cytokines and growth factors. Yet, the mechanisms regulating their production are not fully explored. The release of extracellular vesicles (EVs) in the interstitial space curbs important biological functions, including inflammation, and influences the development of cardiovascular diseases. To date, there is no evidence for in situ release of cardiac EVs after MI. OBJECTIVE: The present study tested the hypothesis that local EV generation in the infarcted heart coordinates cardiac inflammation after MI. METHODS AND RESULTS: Coronary artery ligation in mice transiently increases EV levels in the left ventricle when compared with sham animals. EVs from infarcted hearts were characterized as large vesicles (252±18 nm) expressing cardiomyocyte and endothelial markers and small EVs (118±4 nm) harboring exosomal markers, such as CD (cluster of differentiation) 63 and CD9. Cardiac large EVs generated after MI, but not small EVs or sham EVs, increased the release of IL (interleukin)-6, CCL (chemokine ligand) 2, and CCL7 from fluorescence-activated cell-sorted Ly6C+ cardiac monocytes. EVs of similar diameter were also isolated from fragments of interventricular septum obtained from patients undergoing aortic valve replacement, thus supporting the clinical relevance of our findings in mice. CONCLUSIONS: The present study demonstrates that acute MI transiently increases the generation of cardiac EVs characterized as both exosomes and microvesicles, originating mainly from cardiomyocytes and endothelial cells. EVs accumulating in the ischemic myocardium are rapidly taken up by infiltrating monocytes and regulate local inflammatory responses.

Differences in the clinical management of women and men after detection of a solitary pulmonary nodule in clinical practice.

OBJECTIVES: To explore differences in the clinical management of men and women in the 5 years after detecting a solitary pulmonary nodule (SPN) by chest radiograph or CT in routine clinical practice. METHODS: We followed up 545 men and 347 women with an SPN detected by chest radiograph or CT in a retrospective cohort of 25,422 individuals undergoing routine thoracic imaging in 2010-2011. We compared the frequency of each management strategy (no further test, immediate intervention or follow up) according to sex by means of chi-squared. We estimated the relative risk of women versus men of having been followed up instead of an immediate intervention using multivariate logistic regression. We compared by sex the time between detection of the nodule and lung cancer diagnosis, the time between diagnosis and death by means of Mann-Whitney U test and the cumulative effective dose of radiation in each management strategy by means of t test. RESULTS: Women were more likely than men to have follow-up rather than immediate intervention (aRR = 1.8, CI 1.3-2.7, p = 0.002), particularly in those who underwent CT (aRR = 4.2, CI 1.9-9.3, p < 0.001). The median time between SPN detection and lung cancer diagnosis was higher in women (4.2 months, interquartile range (IQR) 5.1) than in men (1.5 months, IQR 16.2). The mean cumulative effective dose was 21.3 mSv, 19.4 mSv in men and 23.9mv in women (p = 0.023). CONCLUSIONS: Our results could reflect decisions based on a greater suspicion of lung cancer in men. The incidental detection of SPNs is increasing, and it is necessary to establish clear strategies aimed to reduce variability in their management according to patient's sex. KEY POINTS: • After incidental finding of SPN, women were less likely to receive an immediate intervention. • Accumulative radiation was higher in women than in men. • Our results could reflect decisions based on a greater suspicion of lung cancer in men.

The ECHO model proved to be a useful tool to increase clinicians' self-effectiveness for care of patients with Hepatitis C in Argentina.

The ECHO model was developed to expand access to medical care for populations with HCV infection in underserved areas. We aimed to compare HCV treatment outcomes in community-based clinics with the Austral University Hospital (AUH) and to assess improvement in physician knowledge and skills. In October 2015, we established an HCV ECHO clinic at the AUH in Buenos Aires. To evaluate the impact of this programme, we conducted a prospective cohort study comparing treatment for HCV infection at the AUH with healthcare providers from different Argentinean provinces. A survey evaluating skills and competence in HCV care was administered, and results were compared. The primary endpoint was sustained virologic response (SVR) and under direct-acting antivirals. Since the implementation of ECHO clinics, a total of 25 physicians participated in at least one session (median 10.0; IQR 3.0-18.0). SVR rates (n = 437 patients) were 94.2% (95% CI 90.4-96.8) in patients treated at AUH clinic (n = 227/242) and 96.4% (95% CI 92.7-98.5) in those treated at ECHO sites (n = 188/195), with a nonsignificant difference between sites, 2.2% SVR difference (95% CI -0.24-0.06; P = 0.4). We also found a significant improvement in all the evaluated skills and abilities. Replicating the ECHO model helped to improve participants' skills in the management of HCV achieving similar SVR rates. ECHO model was demonstrated to be an effective intervention able to multiply and expand HCV treatment, a critical barrier to access to care that needs to be solved if we are committed with WHO goals to eliminate HCV by 2030.

Selective EGFR (Epidermal Growth Factor Receptor) Deletion in Myeloid Cells Limits Atherosclerosis-Brief Report.

OBJECTIVE: To determine the consequences of specific inhibition of EGFR (epidermal growth factor receptor) in myeloid cells in atherosclerosis development. APPROACH AND RESULTS: Atherosclerotic lesion size was significantly reduced in irradiated Ldlr-/- mice reconstituted with LysMCre+Egfrlox/lox bone marrow, compared with chimeric Ldlr-/- mice reconstituted with LysMCre-Egfrlox/lox bone marrow, after 4 (-43%; P<0.05), 7 (-34%; P<0.05), and 12 weeks (-54%; P<0.001) of high-fat diet. Reduction of lesion size was associated with marked reduction in macrophage accumulation and necrotic core size. Specific deletion of Egfr in myeloid cells reduced TNF-α (tumor necrosis factor-α) and IL (interleukin)-6 production by stimulated macrophages but had no effect on IL-10 and IL-12p70 secretion. Finally, we found that myeloid deletion of Egfr limited cytoskeletal rearrangements and also lipid uptake by macrophages through a downregulation of the scavenger receptor CD36 (cluster of differentiation 36). CONCLUSIONS: Gene deletion of Egfr in myeloid cells limits IL-6 and TNF-α production, lipid uptake, and consecutively reduces atherosclerosis development.

Pedobarography: a novel approach to test the efficacy of treatments for lameness; an experience with mavacoxib in dogs with elbow osteoarthritis.

BACKGROUND: Pedobarographic analyses detect pressure redistribution among limbs and within limbs in humans, equids and dogs. The main objective of this study was to assess the usefulness of a set of pedobarographic parameters for the detection of lameness, as well as for its suitability for assessing the effects of therapies against osteoarthritis in dogs. With this purpose, eleven large-breed lame dogs with unilateral osteoarthritis due to elbow dysplasia were evaluated using a pressure platform prior to (D0) and after 3 months (D90) of treatment with mavacoxib, a COX-2 selective NSAID. The obtained parameters were: pressure distribution between lame and sound limbs, as well as paw area, mean pressure, and peak pressure of both lame and sound limbs. RESULTS: The results showed statistical differences in all these parameters between lame and sound limbs at D0; however, at D90, differences were significantly decreased as result of the treatment, indicating a substantial functional recovery under the study design conditions. CONCLUSIONS: The provided data prove the suitability of this novel technique in canine models for the quantitative and objective assessment of lameness, but also for the evaluation of treatments for lameness caused by articular pain.

Center of pressure limb path differences for the detection of lameness in dogs: a preliminary study.

BACKGROUND: The limb center of pressure (COP) path measures and quantifies the load distribution within a limb in a still or moving subject. Under this premise, the aim of this study was to test whether data derived from this parameter could detect the differences between sound and lame limbs in unilaterally lame dogs with elbow dysplasia. To accomplish this purpose, ten unilaterally lame dogs of similar conformation were walked over a pressure platform. Next, the COP path, in relation to the position of sound and lame limbs, was measured in a coordinate system over a standard paw template obtained by pedobarography during the whole support phase. To compare variables, force platform data (peak vertical force and vertical impulse) from the same animals were obtained. Sound and lame limb statokinesiograms were also obtained while the animals stood still. RESULTS: The statistical analysis clearly showed that COP in lame limbs start cranially and were shorter than sound limbs. In addition, the value of the COP excursion index was lower in lame limbs. Finally, the area of statokinesiograms was greater in lame limbs. CONCLUSION: This methodology based in limb COP characteristics serves to discriminate between sound and lame limbs in dogs with elbow dysplasia.

Assessment of the Efficacy of Platelet-Rich Plasma in the Treatment of Traumatic Canine Fractures.

The role of platelet-rich plasma (PRP) in promoting the healing of bone fractures has not yet been clearly stated. The aim of this prospective clinical study was to evaluate the effectiveness of plasma rich in growth factors (PRGF, a PRP derivate) in the treatment of naturally-occurring bone fractures in dogs. With this objective, sixty-five dogs with radius/ulna or tibia/fibula bone fractures were randomly divided into two groups (PRGF and saline solution (SS) groups) and checked at days 0, 7, 14, 21, 28, 35, 42, 49, 56, 60, 63, 70, 120, and 180. All the fractures were treated with an external skeletal fixation, and pain was controlled with Carprofen. Healing was evaluated by physical examination, limb function, radiography, and by a Likert-type owner satisfaction questionnaire. A faster fracture healing was observed in the PRGF group, with statistically significant differences with respect to the SS group. Swelling at the fracture site was significantly greater at day 14 and 28 in animals injected with PRGF, and more pain on palpation was found in the area at day 28. The injection of PRGF in acute bone fractures accelerates bone healing.

Peripheral post-ischemic vascular repair is impaired in a murine model of Alzheimer's disease.

The pathophysiology of sporadic Alzheimer's disease (AD) remains uncertain. Along with brain amyloid-ß (Aß) deposits and neurofibrillary tangles, cerebrovascular dysfunction is increasingly recognized as fundamental to the pathogenesis of AD. Using an experimental model of limb ischemia in transgenic APPPS1 mice, a model of AD (AD mice), we showed that microvascular impairment also extends to the peripheral vasculature in AD. At D70 following femoral ligation, we evidenced a significant decrease in cutaneous blood flow (- 29%, P < 0.001), collateral recruitment (- 24%, P < 0.001), capillary density (- 22%; P < 0.01) and arteriole density (- 28%; P < 0.05) in hind limbs of AD mice compared to control WT littermates. The reactivity of large arteries was not affected in AD mice, as confirmed by unaltered size, and vasoactive responses to pharmacological stimuli of the femoral artery. We identified blood as the only source of Aß in the hind limb; thus, circulating Aß is likely responsible for the impairment of peripheral vasculature repair mechanisms. The levels of the majority of pro-angiogenic mediators were not significantly modified in AD mice compared to WT mice, except for TGF-ß1 and PlGF-2, both of which are involved in vessel stabilization and decreased in AD mice (P = 0.025 and 0.019, respectively). Importantly, endothelin-1 levels were significantly increased, while those of nitric oxide were decreased in the hind limb of AD mice (P < 0.05). Our results suggest that vascular dysfunction is a systemic disorder in AD mice. Assessment of peripheral vascular function may therefore provide additional tools for early diagnosis and management of AD.

Clearly Detectable, Kinetically Restricted Solid-Solid Phase Transition in cis-Ceramide Monolayers.

Sphingosine [(2 S,3 R,4 E)-2-amino-4-octadecene-1,3-diol] is the most common sphingoid base in mammals. Ceramides are N-acyl sphingosines. Numerous small variations on this canonical structure are known, including the 1-deoxy, the 4,5-dihydro, and many others. However, whenever there is a Δ4 double bond, it adopts the trans (or E) configuration. We synthesized a ceramide containing 4 Z-sphingosine and palmitic acid ( cis-pCer) and studied its behavior in the form of monolayers extended on an air-water interface. cis-pCer acted very differently from the trans isomer in that, upon lateral compression of the monolayer, a solid-solid transition was clearly observed at a mean molecular area ≤44 Å2·molecule-1, whose characteristics depended on the rate of compression. The solid-solid transition, as well as states of domain coexistence, could be imaged by atomic force microscopy and by Brewster-angle microscopy. Atomistic molecular dynamics simulations provided results compatible with the experimentally observed differences between the cis and trans isomers. The data can help in the exploration of other solid-solid transitions in lipids, both in vitro and in vivo, that have gone up to now undetected because of their less obvious change in surface properties along the transition, as compared to cis-pCer.

Posturography and dynamic pedobarography in lame dogs with elbow dysplasia and cranial cruciate ligament rupture.

BACKGROUND: The usefulness of studying posture and its modifications due to locomotor deficiencies of multiple origins has been widely proven in humans. To assess its suitability in the canine species, static posturography and dynamic pedobarography were performed on lame dogs affected with unilateral elbow dysplasia and cranial cruciate ligament rupture by using a pressure platform. With this objective, statokinesiograms and stabilograms, the percentage of pressure distribution between limbs, paw area, mean pressure, and peak pressure, were obtained from lame and sound dogs. These data were compared with Peak Vertical Force values originated from a force platform in the same recording sessions. RESULTS: Significant differences were found in the parameters mentioned above between sound and lame dogs and limbs. CONCLUSIONS: Posturography and pedobarography are useful and reliable for the monitoring of fore and hindlimb lameness in dogs, providing a new set of parameters for lameness detection.

Assessment of static posturography and pedobarography for the detection of unilateral forelimb lameness in ponies.

BACKGROUND: Static posturography and pedobarography are based on the detection of postural imbalance and, consequently, the pressure redistribution between limbs in lame subjects. These techniques have proven to be useful for the detection of lameness in humans and dogs. The main objective of this study was to test the suitability of static posturography and pedobarography in diagnosing lameness in ponies. A pressure platform was used to obtain postural data (statokinesiograms, mean X and Y, length, LFS ratio, and mean velocity) from 10 sound ponies and 7 ponies with unilateral forelimb lameness. Static pedobarographic data (pressure distribution, mean pressure, and peak pressure) were also collected and compared with force plate data (peak vertical force and vertical impulse) obtained from the same animals at the walk. RESULTS: Significant differences were seen between lame and sound ponies for almost all evaluated parameters. With this sample size, differences between lame and sound limbs/groups were detected with a statistical power of 90%, except for mean X and Y. CONCLUSIONS: Static posturography and pedobarography provide a complementary approach for lameness detection in equids.