Evaluation of canine epidermis and keratinocytoids (keratinocytic organoids) by transmission electron microscopy

Abstract Background Skin disease is a common complaint in veterinary medicine. Current models often use live animals. Epidermal organoids (keratinocytoids) are 3D miniature organs created in culture from single epidermal keratinocytes. These keratinocytoids can be used as an alternative to live animal studies to investigate epidermal structures and skin diseases. Hypothesis/Objective This study's objective was to compare ultrastructural morphological features of canine keratinocytoids to those features of normal epidermis. Results Skin and organoids had morphologically similar components, including tight junctions, desmosomes, lamellar bodies and keratin filaments. These structures were similar in both morphology and distribution. Keratinocytes in the organoids had larger and more distinct keratohyalin granules than epidermal keratinocytes and contained small amounts of glycogen. Keratinocytes from the skin showed no glycogen accumulation. Conclusions and Clinical Relevance Canine keratinocytoids are a useful model to study canine epidermal disease from a light microscopy and ultrastructural standpoint.

Clinical findings and prognostic factors for immediate survival in 33 dogs undergoing surgery for biliary peritonitis

Abstract Objective To report demographics, clinical signs, physical examination, diagnostic test results, surgical findings, and prognostic factors for in‐hospital postoperative mortality following biliary peritonitis surgery in dogs. Study design Retrospective, multi‐institutional cohort study. Animals Thirty‐three client‐owned dogs. Methods The medical records of dogs that underwent surgery for biliary peritonitis between 2015 and 2021 were reviewed. Dogs were included if they had a definitive diagnosis of biliary peritonitis and a surgery report. Information on demographics, clinical signs and duration, physical examination findings, laboratory and diagnostic imaging results, surgery, perioperative medical treatment, and complications for each patient was obtained. Statistical analyses were performed to identify risk factors that affected survival. Results Cholecystectomy was the procedure most frequently performed (31/33, 94%). The overall mortality rate was 36% (12/33). Survival was affected negatively by hyperbilirubinemia ( p  = .049), administration of vasopressors ( p  = .002), renal dysfunction ( p  = .008), and number of postoperative complications ( p  = .005). A mortality rate of 50% was observed in dogs with a total bilirubin level greater than 60.5 μmol/L. There was no difference in mortality rate between septic and nonseptic biliary effusions. Conclusion New prognostic factors associated with in‐hospital postoperative mortality in dogs treated surgically for biliary peritonitis were identified, while others that had been reported previously were confirmed. A preoperative bilirubin threshold value associated with a 50% mortality was identified. Clinical significance Additional information that could help to predict survival in dogs with biliary peritonitis has been provided. However, further research is warranted.

Gender disparity in the impact of COVID‐19 on childcare responsibilities and professional standing among specialty small animal surgeons

Abstract Objective The aim of this study was to report the effects of the COVID‐19 pandemic on childcare responsibilities, mental health, and professional relationships of small animal surgeons. Study design Voluntary, non‐incentivized, anonymized 40‐question internet survey deployed November 2021–February 2022. Sample population A total of 333 completed surveys from veterinary surgeons and residents in the USA. Methods Respondents provided information regarding demographics, family composition, effects of the COVID‐19 pandemic on childcare, impact of work‐life balance changes on mental health, and interpersonal work relationships. The influence of variables such as age and gender on these data was analyzed. Associations between demographics and responses were analyzed ( p  < .05). Results Families were most commonly categorized as “children and a partner” (139/312, 44.6%), followed by “partner and no children” (100/312, 32%). A total of 46.5% (67/145) of respondents reported disruptions in school schedules affected their work schedule. Female respondents were most likely affected (OR = 2.2, p  = .047). Respondents experiencing stress due to disruptions in work‐life balance reported three or more feelings of mental distress and were more likely to be female ( p  < .001). Female gender was associated with a delay in promotion, adverse effects on relationships with colleagues, and negative effects on relationships with administration ( p  = .016, p  < .001, p  = .01). Conclusion The COVID‐19 pandemic affected childcare responsibilities, professional standing, and the mental health of veterinary surgeons. Female gender was the most common variable associated with dysregulation of work‐life balance. Clinical impact Identifying variables assists in creating strategies that improve job satisfaction and serve as a foundation for enhancing the profession's preparedness for future disruptions.

Recurrence of cervical intervertebral disc extrusion in 55 dogs after surgical decompression with or without prophylactic fenestration

Abstract Objective To determine whether prophylactic fenestration (PF) of adjacent intervertebral discs decreases the recurrence rate (RR) of cervical intervertebral disc extrusion (C‐IVDE) in small dogs undergoing ventral slot (VS) decompression, and whether PF increases perioperative complication risk. Study design Retrospective, multi‐institutional cohort study. Sample population A total of 55 dogs. Methods Medical records of a mixed population of small dogs (<20 kg) treated with VS for C‐IVDE with a minimum one‐year follow‐up were reviewed. During surgery, dogs underwent either single‐site PF, multiple‐site PF, or no PF. Perioperative complication rate and RR were compared between PF and non‐PF groups using generalized linear models. Surgical time and neurologic grade (presurgery, post‐surgery, at first recheck) were compared with Mann–Whitney test and chi‐squared tests. Results A total of 55 dogs were included (PF: n  = 18; non‐PF: n  = 37). Neurologic grades were similar at all timepoints. Median time to first recheck was 14 days (range: 5–56). Median follow‐up time was 1380 days (range: 365–2777). Recurrence occurred in 25% of dogs (14/55), all in the non‐PF group. Prophylactic fenestration was associated with a lower RR ( p  < .001). Surgery duration was longer in the PF group (158.0 ± 13.5 min) versus non‐PF (118.0 ± 6.8 min, p  = .017), but complication rates were similar (18.2%, p  = .838) between groups. Conclusion Recurrence of C‐IVDE is more likely to occur at non‐PF group than PF‐group in a heterogenous population of small breed dogs. Prophylactic fenestration was not linked to increased complication risk. Clinical significance Prophylactic fenestration might be safely considered to prevent C‐IVDE recurrence.

Comparison of dermal and eschar fibroblasts in full skin equivalents

Abstract Full‐thickness burn wounds pose significant problems, demanding specialised therapies to avoid complications and promote recovery. Eschar tissue, which forms in response to severe burns, contains viable fibroblasts, which migrate from the surrounding tissue in response to burn injury and exhibit a myofibroblast phenotype. The goal of this study was to characterise eschar‐derived fibroblasts and examine their use for engineered in vitro full skin equivalents in comparison to normal dermal fibroblasts, which were harvested from non‐injured skin. Microarray analysis indicated that eschar fibroblasts differ from dermal fibroblasts in various biological processes including inflammation, extracellular matrix formation, cell migration and differentiation. Skin equivalents with eschar fibroblasts showed similarities to those generated using normal dermal fibroblasts in terms of epidermis and dermis formation. However, in contrast to dermal fibroblast‐based full skin equivalents, eschar fibroblast‐based equivalents exhibited macroscopic contractile behaviour. In addition, eschar fibroblasts‐based equivalents demonstrated higher alpha‐smooth muscle actin expression on mRNA and protein levels. In conclusion, our findings suggest that eschar fibroblasts‐based full skin equivalents hold promise as a platform to study burn wound environments as eschar fibroblasts are clinically more relevant fibroblasts and able to mimic certain aspects of the challenging wound environment in vitro.

cAMP reduces action potential amplitude and conduction velocity over long axonal distance

Cathodal weak direct current decreases epileptic excitability with reduced neuronal activity and enhanced delta oscillations

Abstract Seizures are manifestations of hyperexcitability in the brain. Non‐invasive weak current stimulation, delivered through cathodal transcranial direct current stimulation (ctDCS), has emerged to treat refractory epilepsy and seizures, although the cellular‐to‐populational electrophysiological mechanisms remain unclear. Using the ctDCS in vivo model, we investigate how neural excitability is modulated through weak direct currents by analysing the local field potential (LFP) and extracellular unit spike recordings before, during and after ctDCS versus sham stimulation. In rats with kainic acid (KA)‐induced acute hippocampal seizures, ctDCS reduced seizure excitability by decreasing the number and amplitude of epileptic spikes in LFP and enhancing delta (δ) power. We identified unit spikes of putative excitatory neurons in CA1 stratum pyramidale based on waveform sorting and validated via optogenetic inhibitions which increased aberrantly in seizure animals. Notably, cathodal stimulation significantly reduced these unit spikes, whereas anodal stimulation exhibited the opposite effect, showing polarity‐specific and current strength‐dependent responses. The reduced unit spikes after ctDCS coupled to δ oscillations with an increased coupling strength. These effects occurred during stimulation and lasted 90 min post‐stimulation, accompanied by inhibitory short‐term synaptic plasticity changes shown in paired‐pulse stimulation after ctDCS. Consistently, neuronal activations measured by c‐Fos significantly decreased after ctDCS, particularly in CaMKII + ‐excitatory neurons while increased in GAD + ‐inhibitory neurons. In conclusion, epileptic excitability was alleviated with cathodal weak direct current stimulation by diminishing excitatory neuronal activity and enhancing endogenous δ oscillations through strengthened coupling between unit spikes and δ waves, along with inhibitory plasticity changes, highlighting the potential implications to treat brain disorders characterized by hyperexcitability.Key points Electric fields generated by transcranial weak electric current stimulation were measured at CA1, showing polarity‐specific and current strength‐dependent modulation of unit spike activity. Polyspike epileptiform discharges were observed in rats with kainic acid (KA)‐induced hippocampal seizures. Cathodal transcranial direct current stimulation (ctDCS) reduced the number and amplitude of the epileptic spikes in local field potentials (LFPs) while increased δ oscillations. Neuronal unit spikes aberrantly increased in seizures and coupled with epileptiform discharges. ctDCS reduced excitatory neuronal firings at CA1 and strengthened the coupling between unit spikes and δ waves. Neuronal activations, measured by c‐Fos, decreased in CaMKII + ‐excitatory neurons while increased in GAD + ‐inhibitory neurons after ctDCS. These effects on LFP and unit spikes lasted up to 90 min post‐stimulation. Inhibitory short‐term plasticity changes detected through paired‐pulse stimulation underpin the enduring effects of ctDCS on seizures.

Adjuster Absorber Rods Return To Service At Plngs

Optofluidic lab-on-chip for absorbance and fluorescence analysis in protein aggregation studies

Infrasound uncertainty propagation: Ensuring traceability from the laboratory to the field