OBJECTIVE: The study aimed to determine if an ultrasonic Doppler-guided technique (UDGT) leads to improved placement efficacy (time, success) of feline dorsal pedal arterial catheters vs the traditional palpation-guided technique (TPT).
METHODS: A total of 26 adult, client-owned cats requiring sedation or general anesthesia for any reason, aged >12 months and weighing >3.0 kg, and with Doppler blood pressure measurements of at least 80 mmHg were enrolled. Each hindlimb was randomly assigned for dorsal pedal arterial catheterization using either the UDGT or TPT. With the UDGT, the location of the artery was identified by an audible sound using the Doppler. Successful catheter placement was confirmed by visualization of an arterial pressure waveform using a transducer and monitor system attached to the catheter. The Kaplan-Meier method and log-rank test were used to compare the two techniques.
RESULTS: The overall proportion of successful arterial catheterization was 17% (9/52): 19% (5/26) via UDGT and 15% (4/26) via TPT. Among successful arterial catheterizations (n = 9), the mean time to catheterization was 339 ± 198 s: 328 ± 237 s (n = 5) with UDGT and 353 ± 171 s (n = 4) with TPT. The log-rank test showed the two techniques were not significantly different in likelihood of successful arterial catheter placement or time to successful catheterization (P = 0.698). An arterial flash occurred in 62% (32/52) of the limbs, 58% (15/26) with the UDGT and 65% (17/26) with the TPT. Complications (self-limiting bruising, hematoma formation) were observed equally between UDGT (3/26 limbs) and TPT (3/26 limbs) in six cats.
CONCLUSIONS: The UDGT did not improve the efficacy of catheter placement compared with the TPT. Few complications were associated with arterial catheterization.

Sterile inflammation after injury is important for tissue restoration. In injured human and mouse tissues, macrophages were recently found to accumulate perivascularly. This study investigates if macrophages adopt a mural cell phenotype important for restoration after ischemic injury. Single-cell RNA sequencing of fate-mapped macrophages from ischemic mouse muscles demonstrates a macrophage-toward-mural cell switch of a subpopulation of macrophages with downregulated myeloid cell genes and upregulated mural cell genes, including PDGFRβ. This observation was further strengthened when including unspliced transcripts in the analysis. The macrophage switch was proven functionally relevant, as induction of macrophage-specific PDGFRβ deficiency prevented their perivascular macrophage phenotype, impaired vessel maturation and increased vessel leakiness, which ultimately reduced limb function. In conclusion, macrophages in adult ischemic tissue were demonstrated to undergo a cellular program to morphologically, transcriptomically and functionally resemble mural cells while weakening their macrophage identity. The macrophage-to-mural cell-like phenotypic switch is crucial for restoring tissue function and warrants further exploration as a potential target for immunotherapies to enhance healing.

BACKGROUND: Sepsis leads to multiple organ dysfunction and negatively impacts patient outcomes. Skeletal muscle disuse is a significant comorbidity in septic patients during their ICU stay due to prolonged immobilization.
OBJECTIVE: Combination of sepsis and muscle disuse will promote a unique proteomic signature in skeletal muscle in comparison to disuse and sepsis separately.
UNASSIGNED: Following cecal ligation and puncture (CLP) or Sham surgeries, mice were subjected to hindlimb suspension (HLS) or maintained normal ambulation (NA). Tibialis anterior muscles from 24 C57BL6/J male mice were harvested for proteomic analysis. Proteomic profiles were assessed using nano-liquid chromatography with tandem mass spectrometry, followed by data analysis including Partial Least Squares Discriminant Analysis (PLS-DA), to compare the differential protein expression across groups.
RESULTS: A total of 2876 differentially expressed proteins were identified, with marked differences between groups. In mice subjected to CLP and HLS combined, there was a distinctive proteomic signature characterized by a significant decrease in the expression of proteins involved in mitochondrial function and muscle metabolism, alongside a marked increase in proteins related to muscle degradation pathways. The PLS-DA demonstrated a clear separation among experimental groups, highlighting the unique profile of the CLP/HLS group. This suggests an important interaction between sepsis-induced inflammation and disuse atrophy mechanisms in sepsis-induced myopathy.
CONCLUSIONS: Our findings reveal a complex proteomic landscape in skeletal muscle exposed to sepsis and disuse, consistent with an exacerbation of muscle protein degradation under these combined stressors. The identified proteins and their roles in cellular stress responses and muscle pathology provide potential targets for intervention to mitigate muscle dysfunction in septic conditions, highlighting the importance of addressing both sepsis and disuse concurrently in clinical and experimental settings.

Ischemia is a major limiting factor in Vascularized Composite Allotransplantation (VCA) as irreversible muscular injury can occur after as early as 4-6 h of static cold storage (SCS). Organ preservation technologies have led to the development of storage protocols extending rat liver ex vivo preservation up to 4 days. Development of such a protocol for VCAs has the added challenge of inherent ice nucleating factors of the graft, therefore, this study focused on developing a robust protocol for VCA supercooling. Rodent partial hindlimbs underwent subnormothermic machine perfusion (SNMP) with several loading solutions, followed by a storage solution with cryoprotective agents (CPA) developed for VCAs. Storage occurred in suspended animation for 24h and VCAs were recovered using SNMP with modified Steen. This study shows a robust VCA supercooling preservation protocol in a rodent model. Further optimization is expected to allow for its application in a transplantation model, which would be a breakthrough in the field of VCA preservation.

Hoof care providers are pivotal for implementing biomechanical optimizations of the musculoskeletal system in the horse. Regular visits allow for the collection of longitudinal, quantitative information (\"normal ranges\"). Changes in movement symmetry, e.g., after shoeing, are indicative of alterations in weight-bearing and push-off force production. Ten Warmblood show jumping horses (7-13 years; 7 geldings, 3 mares) underwent forelimb re-shoeing with rolled rocker shoes, one limb at a time (\"limb-by-limb\"). Movement symmetry was measured with inertial sensors attached to the head, withers, and pelvis during straight-line trot and lunging. Normalized differences pre/post re-shoeing were compared to published test-retest repeatability values. Mixed-model analysis with random factors horse and limb within horse and fixed factors surface and exercise direction evaluated movement symmetry changes (p < 0.05, Bonferroni correction). Withers movement indicated increased forelimb push-off with the re-shod limb on the inside of the circle and reduced weight-bearing with the re-shod limb and the ipsilateral hind limb on hard ground compared to soft ground. Movement symmetry measurements indicate that a rolled rocker shoe allows for increased push-off on soft ground in trot in a circle. Similar studies should study different types of shoes for improved practically relevant knowledge about shoeing mechanics, working towards evidence-based preventative shoeing.

MicroRNAs (miRs) regulate physiological and pathological processes, including ischemia-induced angiogenesis and neovascularization. They can be transferred between cells by extracellular vesicles (EVs). However, the specific miRs that are packaged in EVs released from skeletal muscles, and how this process is modulated by ischemia, remain to be determined. We used a mouse model of hindlimb ischemia and next generation sequencing (NGS) to perform a complete profiling of miR expression and determine the effect of ischemia in skeletal muscles, and in EVs of different sizes (microvesicles (MVs) and exosomes) released from these muscles. Ischemia significantly modulated miR expression in whole muscles and EVs, increasing the levels of several miRs that can have pro-angiogenic effects (angiomiRs). We found that specific angiomiRs are selectively enriched in MVs and/or exosomes in response to ischemia. In silico approaches indicate that these miRs modulate pathways that play key roles in angiogenesis and neovascularization, including HIF1/VEGF signaling, regulation of actin cytoskeleton and focal adhesion, NOTCH, PI3K/AKT, RAS/MAPK, JAK/STAT, TGFb/SMAD signaling and the NO/cGMP/PKG pathway. Thus, we show for the first time that angiomiRs are selectively enriched in MVs and exosomes released from ischemic muscles. These angiomiRs could be targeted in order to improve the angiogenic function of EVs for potential novel therapeutic applications in patients with severe ischemic vascular diseases.

Neuroactive steroids (NASs) directly affect neuronal excitability. Despite their role in the nervous system is intimately linked to pain control, knowledge is currently limited. This study investigates the peripheral involvement of NASs in chronic ischemic pain by targeting the cytochrome P450 side-chain cleavage enzyme (P450scc). Using a rat model of hind limb thrombus-induced ischemic pain (TIIP), we observed an increase in P450scc expression in the ischemic hind paw skin. Inhibiting P450scc with intraplantar aminoglutethimide (AMG) administration from post-operative day 0 to 3 significantly reduced the development of mechanical allodynia. However, AMG administration from post-operative day 3 to 6 did not affect established mechanical allodynia. In addition, we explored the role of the peripheral sigma-1 receptor (Sig-1R) by co-administering PRE-084 (PRE), a Sig-1R agonist, with AMG. PRE reversed the analgesic effects of AMG during the induction phase. These findings indicate that inhibiting steroidogenesis with AMG alleviates peripheral ischemic pain during the induction phase via Sig-1Rs.

UNASSIGNED: To determine with mechanical nociceptive threshold (MNT) testing whether distal limb skin sensation is affected by intra-articular anesthesia of the tarsometatarsal joint (TMTJ).
UNASSIGNED: This was a prospective cohort study. Ten client-owned horses that had intra-articular TMTJ anesthesia were included in the study. The MNT was measured at 6 sites on the distal limb at 3 time points: before anesthesia (T0) and at 10 min (T10) and 30 min (T30) post-injection. Linear mixed-model analyses were done, with the significance level set at P < 0.05.
UNASSIGNED: There was an increase in MNT (P = 0.001) across combined testing points between T0 and T30, indicating loss of skin sensation in the distal limb 30 min after TMTJ anesthesia. Regarding individual MNT sites, there were increases at the lateral proximal sesamoid bone (P = 0.002) and dorsal coronary band (P = 0.037) at T30 compared to T0.
UNASSIGNED: Intra-articular anesthesia of the TMTJ significantly increased the combined MNT of the skin of the distal limb at 30 min, indicating decreased skin sensation.
UNASSIGNED: Diagnostic anesthesia of the distal hind limb should be performed before TMTJ block. However, if patient compliance prevents this, lameness evaluation 10 min after blocking may enhance the reliability of interpretation.
Effets de l’anesthésie intra-articulaire de l’articulation tarsométatarsienne sur la sensation cutanée du membre distal chez le cheval.
UNASSIGNED: Déterminer à l’aide d’un test de seuil nociceptif mécanique (MNT) si la sensation cutanée du membre distal est affectée par l’anesthésie intra-articulaire de l’articulation tarsométatarsienne (ATMT).
UNASSIGNED: Il s’agissait d’une étude de cohorte prospective. Dix chevaux appartenant à des clients et ayant subi une anesthésie intra-articulaire pour l’ATMT ont été inclus dans l’étude. Le MNT a été mesuré sur 6 sites du membre distal à 3 moments: avant l’anesthésie (T0) et à 10 min (T10) et 30 min (T30) après l’injection. Des analyses linéaires sur modèles mixtes ont été effectuées, avec le niveau de signification fixé à P < 0,05.
UNASSIGNED: Il y avait une augmentation du MNT (P = 0,001) sur tous les points de test combinés entre T0 et T30, indiquant une perte de sensation cutanée dans le membre distal 30 minutes après l’anesthésie du ATMT. En ce qui concerne les sites MNT individuels, il y avait des augmentations au niveau de l’os sésamoïde proximal latéral (P = 0,002) et de la bande coronaire dorsale (P = 0,037) à T30 par rapport à T0.
UNASSIGNED: L’anesthésie intra-articulaire du ATMT a augmenté de manière significative le MNT combiné de la peau du membre distal à 30 min, indiquant une diminution de la sensation cutanée.
UNASSIGNED: Une anesthésie diagnostique du membre postérieur distal doit être réalisée avant le bloc de l’ATMT. Cependant, si l’observance du patient l’empêche, l’évaluation de la boiterie 10 minutes après le blocage peut améliorer la fiabilité de l’interprétation.(Traduit par Dr Serge Messier).

BACKGROUND: Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide pivotal in migraine pathophysiology and is considered a promising new migraine drug target. Although intravenous PACAP triggers migraine attacks and a recent phase II trial with a PACAP-inhibiting antibody showed efficacy in migraine prevention, targeting the PACAP receptor PAC1 alone has been unsuccessful. The present study investigated the role of three PACAP receptors (PAC1, VPAC1 and VPAC2) in inducing migraine-relevant hypersensitivity in mice.
METHODS: Hindpaw hypersensitivity was induced by repeated PACAP38 injections. Tactile sensitivity responses were quantified using von Frey filaments in three knockout (KO) mouse strains, each lacking one of the PACAP-receptors (Ntotal = 160). Additionally, ex vivo wire myography was used to assess vasoactivity of the carotid artery, and gene expression of PACAP receptors was examined by qPCR.
RESULTS: PACAP38 induced hypersensitivity in WT controls (p < 0.01) that was diminished in VPAC1 and VPAC2 KO mice (p < 0.05). In contrast, PAC1 KO mice showed similar responses to WT controls (p > 0.05). Myograph experiments supported these findings showing diminished vasoactivity in VPAC1 and VPAC2 KO mice. We found no upregulation of the non-modified PACAP receptors in KO mice.
CONCLUSIONS: This study assessed all three PACAP receptors in a migraine mouse model and suggests a significant role of VPAC receptors in migraine pathophysiology. The lack of hypersensitivity reduction in PAC1 KO mice suggests the involvement of other PACAP receptors or compensatory mechanisms. The results indicate that targeting only individual PACAP receptors may not be an effective migraine treatment.

BACKGROUND: This study explores the potential role of Thioredoxin-interacting protein (TXNIP) silencing in endothelial colony-forming cells (ECFCs) within the scope of age-related comorbidities and impaired vascular repair. We aim to elucidate the effects of TXNIP silencing on vasculogenic properties, paracrine secretion, and neutrophil recruitment under conditions of metabolic stress.
METHODS: ECFCs, isolated from human blood cord, were transfected with TXNIP siRNA and exposed to a high glucose and β-hydroxybutyrate (BHB) medium to simulate metabolic stress. We evaluated the effects of TXNIP silencing on ECFCs\' functional and secretory responses under these conditions. Assessments included analyses of gene and protein expression profiles, vasculogenic properties, cytokine secretion and neutrophil recruitment both in vitro and in vivo. The in vivo effects were examined using a murine model of hindlimb ischemia to observe the physiological relevance of TXNIP modulation under metabolic disorders.
RESULTS: TXNIP silencing did not mitigate the adverse effects on cell recruitment, vasculogenic properties, or senescence induced by metabolic stress in ECFCs. However, it significantly reduced IL-8 secretion and consequent neutrophil recruitment under these conditions. In a mouse model of hindlimb ischemia, endothelial deletion of TXNIP reduced MIP-2 secretion and prevented increased neutrophil recruitment induced by age-related comorbidities.
CONCLUSIONS: Our findings suggest that targeting TXNIP in ECFCs may alleviate ischemic complications exacerbated by metabolic stress, offering potential clinical benefits for patients suffering from age-related comorbidities.