Treatment of aged wound healing models with FGF2 and ABT-737 reduces the senescent cell population and increases wound closure rate.

Delayed tissue repair in the aged presents a major socio-economic and clinical problem. Age-associated delay in wound healing can be attributed to multiple factors, including an increased presence of senescent cells persisting in the wound. Although the transient presence of senescent cells is physiologic during the resolution phase of normal healing, increased senescent cell accumulation with age can negatively impact tissue repair. The objective of the study was to test interventional strategies that could mitigate the negative effect of senescent cell accumulation and possibly improve the age-associated delay in wound healing. We utilised a 3D in vitro senescent fibroblast populated collagen matrix (FPCM) to study cellular events associated with senescence and delayed healing. Senescent fibroblasts showed an increase in anti-apoptotic B-cell lymphoma 2 (BCL-2) family proteins. We hypothesized that reducing the senescent cell population and promoting non-senescent cell functionality would mitigate the negative effect of senescence and improve healing kinetics. BCL-2 inhibition and mitogen stimulation (FGF2) improved healing in the in vitro senescent models. These results were confirmed with an ex vivo human skin biopsy model. These data suggested that modulation of the senescent cell population with soluble factors improved the healing outcome in our in vitro and ex vivo healing models.

Preclinical Evaluation of a Humanized, Near-Infrared Fluorescent Antibody for Fluorescence-Guided Surgery of MUC16-Expressing Pancreatic Cancer.

Surgery remains the only potentially curative treatment option for pancreatic cancer, but resections are made more difficult by infiltrative disease, proximity of critical vasculature, peritumoral inflammation, and dense stroma. Surgeons are limited to tactile and visual cues to differentiate cancerous tissue from normal tissue. Furthermore, translating preoperative images to the intraoperative setting poses additional challenges for tumor detection, and can result in undetected and unresected lesions. Thus, pancreatic ductal adenocarcinoma (PDAC) has high rates of incomplete resections, and subsequently, disease recurrence. Fluorescence-guided surgery (FGS) has emerged as a method to improve intraoperative detection of cancer and ultimately improve surgical outcomes. Initial clinical trials have demonstrated feasibility of FGS for PDAC, but there are limited targeted probes under investigation for this disease, highlighting the need for development of additional novel biomarkers to reflect the PDAC heterogeneity. MUCIN16 (MUC16) is a glycoprotein that is overexpressed in 60-80% of PDAC. In our previous work, we developed a MUC16-targeted murine antibody near-infrared conjugate, termed AR9.6-IRDye800, that showed efficacy in detecting pancreatic cancer. To build on the translational potential of this imaging probe, a humanized variant of the AR9.6 fluorescent conjugate was developed and investigated herein. This conjugate, termed huAR9.6-IRDye800, showed equivalent binding properties to its murine counterpart. Using an optimized dye:protein ratio of 1:1, in vivo studies demonstrated high tumor to background ratios in MUC16-expressing tumor models, and delineation of tumors in a patient-derived xenograft model. Safety, biodistribution, and toxicity studies were conducted. These studies demonstrated that huAR9.6-IRDye800 was safe, did not yield evidence of histological toxicity, and was well tolerated in vivo. The results from this work suggest that AR9.6-IRDye800 is an efficacious and safe imaging agent for identifying pancreatic cancer intraoperatively through fluorescence-guided surgery.

Preperitoneal insufflation pressure of the abdominal wall in a porcine model.

BACKGROUND: Most complications and adverse events during laparoscopic surgery occur during initial entry into the peritoneal cavity. Among them, preperitoneal insufflation occurs when the insufflation needle is incorrectly placed, and the abdominal wall is insufflated. The objective of this study was to find a range for static pressure which is low enough to allow placement of a Veress needle into the peritoneal space without causing preperitoneal insufflation, yet high enough to separate abdominal viscera from the parietal peritoneum. METHODS: A pressure test was performed on twelve fresh porcine carcasses to determine the minimum preperitoneal insufflation pressure and the minimum initial peritoneal cavity insufflation pressure. Each porcine model had five needle placement categories. One category tested the initial peritoneal cavity insufflation pressure beneath the umbilicus. The four remaining categories tested the preperitoneal insufflation pressure at four different anatomical locations on the abdomen that can be used for initial entry. The minimum initial insufflation pressures from each carcass were then compared to the preperitoneal insufflation pressures to obtain an optimal range for initial insufflation. RESULTS: Increasing the insufflation pressure increased the probability of preperitoneal insufflation. Also, there was a statistically significant difference (p < 0.05) between the initial peritoneal cavity insufflation pressures (8.83 ± 4.19 mmHg) and the lowest preperitoneal pressures (32.54 ± 7.84 mmHg) (mean ± SD). CONCLUSION: Pressures greater than 10 mmHg resulted in initial cavity insufflation and pressures greater than 20 mmHg resulted in preperitoneal insufflation in porcine models. By knowing the minimum pressure required to separate the layers of the abdominal wall, the risk of preperitoneal insufflation can be mitigated while obtaining safe and efficient entry into the peritoneal cavity. The findings in this research are not a guideline for trocar or Veress needle placement, but instead reveal preliminary data which may lead to more studies, technology, etc.

Ultra-absorptive Nanofiber Swabs for Improved Collection and Test Sensitivity of SARS-CoV-2 and other Biological Specimens.

Following the COVID-19 outbreak, swabs for biological specimen collection were thrust to the forefront of healthcare materials. Swab sample collection and recovery are vital for reducing false negative diagnostic tests, early detection of pathogens, and harvesting DNA from limited biological samples. In this study, we report a new class of nanofiber swabs tipped with hierarchical 3D nanofiber objects produced by expanding electrospun membranes with a solids-of-revolution-inspired gas foaming technique. Nanofiber swabs significantly improve absorption and release of proteins, cells, bacteria, DNA, and viruses from solutions and surfaces. Implementation of nanofiber swabs in SARS-CoV-2 detection reduces the false negative rates at two viral concentrations and identifies SARS-CoV-2 at a 10× lower viral concentration compared to flocked and cotton swabs. The nanofiber swabs show great promise in improving test sensitivity, potentially leading to timely and accurate diagnosis of many diseases.

Caregiver burden, treatment complexity, and the veterinarian-client relationship in owners of dog with skin disease.

BACKGROUND: Increasing complexity of treatment plans is associated with higher levels of caregiver burden in owners of dogs with skin disease. It is possible that elevated caregiver burden resulting from treatment complexity could, in turn, affect the veterinarian-client relationship. HYPOTHESES/OBJECTIVES: We expected that treatment complexity, caregiver burden, and the client's perception of the veterinarian-client relationship would be related to each other. We also expected an indirect effect of caregiver burden on the cross-sectional association between treatment complexity and the veterinarian-client relationship, and that this effect would be robust to adjustment for the dog's skin disease course and severity. PARTICIPANTS: Participants were 349 owners of dogs with skin disease recruited through online consumer panels. MATERIALS AND METHODS: Cross-sectional online assessments were completed for caregiver burden, treatment plan complexity, veterinarian-client relationship, and skin disease course and severity. Demographic information also was collected. RESULTS: The indirect effect of caregiver burden on the relationship between treatment complexity and veterinarian-client relationship was statistically significant, accounting for 42.76% of the variance in the model. After controlling for disease severity and course, that effect remained statistically significant, accounting for 37.76% of the variance. CONCLUSIONS AND CLINICAL IMPORTANCE: Findings support the notion that greater treatment complexity is related to the owner's perception of the veterinarian-client relationship via caregiver burden. Efforts to reduce caregiver burden by using the simplest effective treatment may benefit the veterinarian-client relationship.

Contexte - La complexité croissante des plans de traitement est associée à des niveaux plus élevés de fardeau pour les soignants propriétaires de chiens atteints de maladies de peau. Il est possible que le fardeau élevé des soignants résultant de la complexité du traitement pourrait, à son tour, affecter la relation vétérinaire-client. Hypothèses/Objectifs - Nous nous attendions à ce que la complexité du traitement, le fardeau des soignants et la perception du client de la relation vétérinaire-client seraient liés les uns aux autres. Nous nous attendions également à un effet indirect de le fardeau du soignant sur l'association transversale entre la complexité du traitement et le vétérinaire-client relation, et que cet effet serait robuste à l'ajustement de l'évolution et de la gravité de la maladie de peau du chien. Participants - Les participants étaient 349 propriétaires de chiens atteints de maladies de la peau recrutés par le biais de consommateurs en ligne panneaux. Matériels et méthodes - Des évaluations transversales en ligne ont été réalisées pour le fardeau des soignants, le traitement la complexité du plan, la relation vétérinaire-client et l'évolution et la gravité des maladies de la peau. Informations démographiques a également été collecté. Résultats - L'effet indirect du fardeau des soignants sur la relation entre la complexité du traitement et le vétérinaire-la relation client était statistiquement significative, représentant 42,76 % de la variance du modèle. Après contrôle pour la gravité et l'évolution de la maladie, cet effet est resté statistiquement significatif, représentant 37,76 % des la variance. Conclusions et importance clinique - Les résultats appuient l'idée qu'une plus grande complexité du traitement est liée à la perception du propriétaire de la relation vétérinaire-client via le fardeau des soignants. Efforts pour réduire le soignant fardeau en utilisant le traitement efficace le plus simple peut être bénéfique pour la relation vétérinaire-client.

Contexto - O aumento da complexidade dos planos de tratamento está associado a altos níveis de sobrecarga do cuidador de cães com doenças de pele. É possível que a sobrecarga do cuidador elevada resultante da complexidade da terapia possa, desta forma, afetar a relação veterinário-cliente. Hipótese/Objetivos - Nós imaginamos que a complexidade do tratamento, a sobrecarga do cuidador, e a percepção do cliente da relação veterinário-cliente estariam relacionadas. Nós também imaginamos que poderia uma mediação da sobrecarga do cuidador na associação transversal entre a complexidade do tratamento e a relação veterinário-cliente, e que este efeito seria robusto para ajustar o curso e a gravidade da doença de pele do cão. Participantes - Os participantes foram 349 tutores de cães com doença de pele recrutados através de formulários online. Materiais e métodos - Avaliações transversais online foram preenchidas para sobrecarga do cuidador, complexidade do plano de tratamento, relação veterinário-cliente, e curso da doença de pele e gravidade. Dados demográficos também foram coletados. Resultados - O efeito indireto da sobrecarga do cuidador na relação entre a complexidade do tratamento e a relação veterinário-cliente foi significativamente significativa, sendo responsável por 42,76% da variância no modelo. Após controlar para gravidade da doença e curso, esse efeito permaneceu estatisticamente significativo, respondendo por 37,76% da variância. Conclusões e importância clínica - Os achados corroboram com a ideia de que a complexidade do tratamento está relacionada à percepção do tutor sobre a relação veterinário-cliente pela sobrecarga do cuidador. Esforços para reduzir a sobrecarga do cuidador utilizando planos terapêuticos mais simples podem beneficiar a relação veterinário-cliente.

Introducción- el aumento de la complejidad de los planes de tratamiento se asocia a mayores niveles de responsabilidad de los propietarios de perros con enfermedades de la piel. Es posible que esta mayor carga para el propietario resultante de la complejidad del tratamiento pueda, a su vez, afectar a la relación veterinario-cliente. Hipótesis/Objetivos- esperábamos que la complejidad del tratamiento, la mayor responsabilidad para cuidadores y la percepción de los propietarios de la relación veterinario-cliente estuvieran relacionadas entre sí. También esperábamos un efecto de mediación de la mayor carga del cuidador en la asociación transversal entre la complejidad del tratamiento y la relación veterinario-cliente, y que este efecto sería sólido para el ajuste del curso y la gravedad de la enfermedad de la piel del perro. Participantes- los participantes fueron 349 propietarios de perros con enfermedades de la piel reclutados a través de paneles de consumidores vía telemática. Materiales y métodos- se completaron evaluaciones transversales en línea sobre la carga del cuidador, la complejidad del plan de tratamiento, la relación veterinario-cliente y el curso y la gravedad de la enfermedad de la piel. También se recopiló información demográfica. Resultados - El efecto indirecto de la carga del cuidador sobre la relación entre la complejidad del tratamiento y la relación veterinario-cliente fue estadísticamente significativo, explicando el 42,76% de la varianza del modelo. Después de controlar la gravedad y el curso de la enfermedad, ese efecto siguió siendo estadísticamente significativo y representó el 37,76 % de la varianza. Conclusiones e importancia clínica- los hallazgos respaldan la noción de que una mayor complejidad del tratamiento está relacionada con la percepción del propietario de la relación veterinario-cliente mediante una mayor carga del cuidador. Esfuerzos para reducir la carga del cuidador mediante el uso de tratamientos efectivos más simples pueden beneficiar a la relación veterinario-cliente.

Treatment complexity and caregiver burden are linked in owners of dogs with allergic/atopic dermatitis.

BACKGROUND: Skin disease severity and treatment plan complexity are both related to owner experience of caregiver burden; however, to date they have not been examined simultaneously in owners of dogs with atopic or other chronic allergic dermatitis. HYPOTHESES/OBJECTIVES: We expected to replicate and extend previous work by showing that caregiver burden is linked to treatment complexity and disease severity in this population. Moreover, we hypothesized that a relationship between burden and treatment complexity would be present in both subjective (owner report of experience) and objective (number of weekly treatments) measures, and that these relationships would exist independent of skin disease severity. PARTICIPANTS: Eighty-six owners of dogs with atopic or other chronic allergic dermatitis recruited through social media dog allergy groups. METHODS AND MATERIALS: Cross-sectional online assessments were completed for caregiver burden, treatment plan complexity and skin disease severity. RESULTS: Caregiver burden was correlated with skin disease severity (r = 0.40) and both subjective (r = 0.37) and objective (r =0.30) measures of treatment complexity (P < 0.01 for all). Relationships between caregiver burden and treatment complexity remained significant after accounting for skin disease severity. CONCLUSIONS AND CLINICAL IMPORTANCE: Greater treatment plan complexity is associated with higher caregiver burden in owners of dogs with atopic or other chronic allergic dermatitis. The independence of this relationship highlights the importance of simplicity in effective treatment planning.

Collateral Development and Arteriogenesis in Hindlimbs of Swine After Ligation of Arterial Inflow.

BACKGROUND: Development of collateral vasculature is key in compensating for arterial occlusions in patients with peripheral artery disease (PAD). We aimed to examine the development of collateral pathways after ligation of native vessels in a porcine model of PAD. METHODS: Right hindlimb ischemia was induced in domestic swine (n = 11) using two versions of arterial ligation. Version 1 (n = 6) consisted of ligation with division of the right external iliac, profunda femoral, and superficial femoral arteries. Version 2 (n = 5) consisted of the ligation of version 1 with additional ligation with division of the right internal iliac artery. Development of collateral pathways was evaluated with standard angiography before arterial ligation and at termination (30 days later). Relative luminal diameter of the arteries supplying the ischemic right hind limb were determined by two-dimensional angiography. RESULTS: The dominant collateral pathway that developed after version 1 ligation connected the right internal iliac artery to the right profunda femoral and then to the right superficial femoral and popliteal artery. Mean luminal diameter of the right internal iliac artery at termination increased by 38% compared with baseline. Two codominant collateral pathways developed in version 2 ligation: (i) from the left profunda femoral artery to the reconstituted right profunda femoral artery and (ii) from the common internal iliac trunk and the left internal iliac artery to the reconstituted right internal iliac artery, which then supplied the right profunda femoral and then the right superficial femoral and popliteal artery. The mean diameter of the left profunda and the left internal iliac artery increased at termination by 26% and 21%, respectively (P < 0.05). CONCLUSIONS: Two versions of hindlimb ischemia induction (right ilio-femoral artery ligation with and without right internal iliac artery ligation) in swine produced differing collateral pathways, along with changes to the diameter of the inflow vessels (i.e., arteriogenesis).

Three-Dimensional Objects Consisting of Hierarchically Assembled Nanofibers with Controlled Alignments for Regenerative Medicine.

Assembling electrospun nanofibers with controlled alignment into three-dimensional (3D), complex, and predesigned shapes has proven to be a difficult task for regenerative medicine. Herein, we report a novel approach inspired by solids of revolution that transforms two-dimensional (2D) nanofiber mats of a controlled thickness into once-inaccessible 3D objects with predesigned shapes. The 3D objects are highly porous, consisting of layers of aligned nanofibers separated by gaps ranging from several micrometers to several millimeters. Upon compression, the objects are able to recover their original shapes. The porous objects can serve as scaffolds, guiding the organization of cells and producing highly ordered 3D tissue constructs. Additionally, subcutaneous implantation in rats demonstrates that the 3D objects enable rapid cell penetration, new blood vessel formation, and collagen matrix deposition. This new class of 3D hierarchical nanofiber architectures offers promising advancements in both in vitro engineering of complex 3D tissue constructs/models or organs and in vivo tissue repair and regeneration.

Nanofiber Dressings Topically Delivering Molecularly Engineered Human Cathelicidin Peptides for the Treatment of Biofilms in Chronic Wounds.

Biofilms of multidrug-resistant bacteria in chronic wounds pose a great challenge in wound care. Herein, we report the topical delivery of molecularly engineered antimicrobial peptides using electrospun nanofiber dressings as a carrier for the treatment of biofilms of multidrug-resistant bacteria in diabetic wounds. Molecularly engineered human cathelicidin peptide 17BIPHE2 was successfully encapsulated in the core of pluronic F127/17BIPHE2-PCL core-shell nanofibers. The in vitro release profiles of 17BIPHE2 showed an in initial burst followed by a sustained release over 4 weeks. The peptide nanofiber formulations effectively killed methicillin-resistant Staphylococcus aureus (MRSA) USA300. Similarly, the 17BIPHE2 peptide containing nanofibers could also effectively kill other bacteria including Klebsiella pneumoniae (104 to 106 CFU) and Acinetobacter baumannii (104 to 107 CFU) clinical strains in vitro without showing evident cytotoxicity to skin cells and monocytes. Importantly, 17BIPHE2-containing nanofiber dressings without debridement caused five-magnitude decreases of the MRSA USA300 CFU in a biofilm-containing chronic wound model based on type II diabetic mice. In combination with debridement, 17BIPHE2-containing nanofiber dressings could completely eliminate the biofilms, providing one possible solution to chronic wound treatment. Taken together, the biodegradable nanofiber-based wound dressings developed in this study can be utilized to effectively deliver molecularly engineered peptides to treat biofilm-containing chronic wounds.

Caregiver burden in the veterinary dermatology client: comparison to healthy controls and relationship to quality of life.

BACKGROUND: Skin disease in companion animals often requires long-term management which may contribute to caregiver burden in the dermatology client. HYPOTHESES/OBJECTIVES: We expected greater caregiver burden in dermatology clients relative to healthy control veterinary clients and that no difference would be present between healthy controls and dermatology clients reporting good skin disease control. Within the dermatology sample, we hypothesized that greater caregiver burden would correlate with client perception of the animal's severity of disease (ASD), animal skin disease quality of life (ASD-QoL), and client general quality of life (CG-QoL) and skin disease-related quality of life (CSD-QoL). PARTICIPANTS: Participants were 358 dog owners, including veterinary dermatology clients (n = 152) and healthy general veterinary control clients (n = 206). METHODS AND MATERIALS: Cross-sectional online assessments were completed for client caregiver burden (both samples) and CG-QoL, CSD-QoL, ASD-QoL and ASD (dermatology sample only). RESULTS: Caregiver burden was greater in dermatology clients overall relative to healthy controls (P < 0.001); it was comparable for those reporting good skin disease control (P > 0.05). Within the dermatology group, correlations between caregiver burden and CSD-QoL were high (r = 0.58; P < 0.001). CG-QoL was predicted by caregiver burden (P < 0.001) but not significantly by CSD-QoL (P > 0.05). CONCLUSIONS AND CLINICAL IMPORTANCE: In the presence of good skin disease control, caregiver burden in dermatology clients is as low as general veterinary clients with a healthy dog. Understanding client experiences of companion animal skin disease may be optimized by assessing caregiver burden.

Subclinical Atrial Fibrillation in Older Patients.

BACKGROUND: Long-term continuous electrocardiographic monitoring shows a substantial prevalence of asymptomatic, subclinical atrial fibrillation (SCAF) in patients with pacemakers and patients with cryptogenic stroke. Whether SCAF is also common in other patients without these conditions is unknown. METHODS: We implanted subcutaneous electrocardiographic monitors (St. Jude CONFIRM-AF) in patients ≥65 years of age attending cardiovascular or neurology outpatient clinics if they had no history of atrial fibrillation but had any of the following: CHA2DS2-VASc score of ≥2, sleep apnea, or body mass index >30 kg/m2. Eligibility also required either left atrial enlargement (≥4.4 cm or volume ≥58 mL) or increased (≥290 pg/mL) serum NT-proBNP (N-terminal pro-B-type natriuretic peptide). Patients were monitored for SCAF lasting ≥5 minutes. RESULTS: Two hundred fifty-six patients were followed up for 16.3±3.8 months. Baseline age was 74±6 years; mean CHA2DS2-VASc score was 4.1±1.4; left atrial diameter averaged 4.7±0.8 cm; and 48% had a prior stroke, transient ischemic attack, or systemic embolism. SCAF ≥5 minutes was detected in 90 patients (detection rate, 34.4%/y; 95% confidence interval [CI], 27.7-42.3). Baseline predictors of SCAF were increased age (hazard ratio [HR] per decade, 1.55; 95% CI, 1.11-2.15), left atrial dimension (HR per centimeter diameter, 1.43; 95% CI, 1.09-1.86), and blood pressure (HR per 10 mm Hg, 0.87; 95% CI, 0.78-0.98), but not prior stroke. The rate of occurrence of SCAF in those with a history of stroke, systemic embolism, or transient ischemic attack was 39.4%/y versus 30.3%/y without (P=0.32). The cumulative SCAF detection rate was higher (51.9%/y) in those with left atrial volume above the median value of 73.5 mL. CONCLUSIONS: SCAF is frequently detected by continuous electrocardiographic monitoring in older patients without a history of atrial fibrillation who are attending outpatient cardiology and neurology clinics. Its clinical significance is unclear. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01694394.

Twisting electrospun nanofiber fine strips into functional sutures for sustained co-delivery of gentamicin and silver.

Surgical site infections (SSIs) represent the most common nosocomial infection among surgical patients. In order to prevent SSIs in a sustained manner and lessen side effects, we developed a twisting method for generation of nanofiber-based sutures capable of simultaneous delivery of silver and gentamicin. The prepared sutures are composed of core-sheath nanofibers with gentamicin/pluronic F127 in the core and silver/PCL in the sheath produced by co-axial electrospinning. The diameters of obtained sutures range from ~80 µm to ~1.2 mm. The in vitro release profiles of silver and gentamicin exhibit an initial burst followed by a sustained release over 5 weeks. The co-encapsulated sutures were able to kill bacteria much more effectively than gentamicin or silver alone loaded nanofiber sutures, without showing obvious impact on proliferation and migration of dermal fibroblasts and keratinocytes. The gentamicin and silver co-loaded PCL nanofiber sutures may hold great potential for prevention of SSIs.

Temporal relationship between subclinical atrial fibrillation and embolic events.

BACKGROUND: Among patients with implantable pacemakers and defibrillators, subclinical atrial fibrillation (SCAF) is associated with an increased risk of stroke; however, there is limited understanding of their temporal relationship. METHODS AND RESULTS: The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial (ASSERT) enrolled 2580 pacemaker and defibrillator patients aged ≥65 years with a history of hypertension but without a history of atrial fibrillation. Pacemakers and implantable cardioverter-defibrillators precisely logged the time and duration of all episodes of SCAF and recorded electrograms that were adjudicated by experts. We examined the temporal relationship between SCAF >6 minutes in duration and stroke or systemic embolism. Of 51 patients who experienced stroke or systemic embolism during follow-up, 26 (51%) had SCAF. In 18 patients (35%), SCAF was detected before stroke or systemic embolism. However, only 4 patients (8%) had SCAF detected within 30 days before stroke or systemic embolism, and only 1 of these 4 patients was experiencing SCAF at the time of the stroke. In the 14 patients with SCAF detected >30 days before stroke or systemic embolism, the most recent episode occurred at a median interval of 339 days (25th to 75th percentile, 211-619) earlier. Eight patients (16%) had SCAF detected only after their stroke, despite continuous monitoring for a median duration of 228 days (25th to 75th percentile, 202-719) before their event. CONCLUSIONS: Although SCAF is associated with an increased risk of stroke and embolism, very few patients had SCAF in the month before their event. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00256152.

Subclinical atrial fibrillation and the risk of stroke.

BACKGROUND: One quarter of strokes are of unknown cause, and subclinical atrial fibrillation may be a common etiologic factor. Pacemakers can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented atrial fibrillation. We evaluated whether subclinical episodes of rapid atrial rate detected by implanted devices were associated with an increased risk of ischemic stroke in patients who did not have other evidence of atrial fibrillation. METHODS: We enrolled 2580 patients, 65 years of age or older, with hypertension and no history of atrial fibrillation, in whom a pacemaker or defibrillator had recently been implanted. We monitored the patients for 3 months to detect subclinical atrial tachyarrhythmias (episodes of atrial rate >190 beats per minute for more than 6 minutes) and followed them for a mean of 2.5 years for the primary outcome of ischemic stroke or systemic embolism. Patients with pacemakers were randomly assigned to receive or not to receive continuous atrial overdrive pacing. RESULTS: By 3 months, subclinical atrial tachyarrhythmias detected by implanted devices had occurred in 261 patients (10.1%). Subclinical atrial tachyarrhythmias were associated with an increased risk of clinical atrial fibrillation (hazard ratio, 5.56; 95% confidence interval [CI], 3.78 to 8.17; P<0.001) and of ischemic stroke or systemic embolism (hazard ratio, 2.49; 95% CI, 1.28 to 4.85; P=0.007). Of 51 patients who had a primary outcome event, 11 had had subclinical atrial tachyarrhythmias detected by 3 months, and none had had clinical atrial fibrillation by 3 months. The population attributable risk of stroke or systemic embolism associated with subclinical atrial tachyarrhythmias was 13%. Subclinical atrial tachyarrhythmias remained predictive of the primary outcome after adjustment for predictors of stroke (hazard ratio, 2.50; 95% CI, 1.28 to 4.89; P=0.008). Continuous atrial overdrive pacing did not prevent atrial fibrillation. CONCLUSIONS: Subclinical atrial tachyarrhythmias, without clinical atrial fibrillation, occurred frequently in patients with pacemakers and were associated with a significantly increased risk of ischemic stroke or systemic embolism. (Funded by St. Jude Medical; ASSERT ClinicalTrials.gov number, NCT00256152.).

A totally recombinant human fibrin sealant.

BACKGROUND: Applications of plasma-derived human fibrin sealants (pdhFS) have been limited because of cost, limited supply of pathogen-screened plasma, the need for bioengineering improvements, and regulatory issues associated with federal approval. We describe a totally recombinant human fibrin sealant (rhFS), which may engender an abundant, safe, and cost-effective supply of efficacious fibrin sealant. MATERIALS AND METHODS: A first-generation rhFS made from recombinant human fibrinogen (rhFI; produced in the milk of transgenic cows), activated recombinant human factor XIII (rhFXIIIa; produced in yeast), and recombinant human thrombin (rhFIIa; purchased, made in animal cell culture) was formulated using thromboelastography (TEG). The hemostatic efficacy of rhFS versus commercial pdhFS was compared in a nonlethal porcine hepatic wedge excision model. RESULTS: The maximal clot strength of rhFS measured in vitro by TEG was not statistically different than that of pdhFS. TEG analysis also showed that the rhFS gained strength more quickly as reflected by a steeper α angle; however, the rhFS achieved this clot strength with a 5-fold lower factor I content than the pdhFS. When these fibrin sealants were studied in a porcine hepatic wedge excision model, the hemostatic scores of the rhFS were equivalent or better than that of the pdhFS. CONCLUSIONS: The bioengineered rhFS had equivalent or better hemostatic efficacy than the pdhFS in a nonlethal hemorrhage model, despite the factor I concentration in the rhFS being about one-fifth that in the pdhFS. Because the rhFS is amenable to large-scale production, the rhFS has the potential to be more economical and abundant than the pdhFS, while having a decreased risk of blood-borne pathogen transmission.

The importance of both fibroblasts and keratinocytes in a bilayered living cellular construct used in wound healing.

Cross talk between fibroblasts and keratinocytes, which maintains skin homeostasis, is disrupted in chronic wounds. For venous leg ulcers and diabetic foot ulcers, a bilayered living cellular construct (BLCC), containing both fibroblasts and keratinocytes that participate in cross talk, is a safe and effective product in healing chronic wounds. To show the importance of both cell types in BLCC, constructs were generated containing only fibroblasts or only keratinocytes and compared directly to BLCC via histology, mechanical testing, gene/protein analysis, and angiogenesis assays. BLCC contained a fully differentiated epithelium and showed greater tensile strength compared with one-cell-type constructs, most likely due to formation of intact basement membrane and well-established stratum corneum in BLCC. Furthermore, expression of important wound healing genes, cytokines, and growth factors was modulated by the cells in BLCC compared with constructs containing only one cell type. Finally, conditioned medium from BLCC promoted greater endothelial network formation compared with media from one-cell-type constructs. Overall, this study characterized a commercially available wound healing product and showed that the presence of both fibroblasts and keratinocytes in BLCC contributed to epithelial stratification, greater tensile strength, modulation of cytokine and growth factor expression, and increased angiogenic properties compared with constructs containing fibroblasts or keratinocytes alone.

Expression of green fluorescent protein in human foreskin fibroblasts for use in 2D and 3D culture models.

The availability of fibroblasts that express green fluorescent protein (GFP) would be of interest for the monitoring of cell growth, migration, contraction, and other processes within the fibroblast-populated collagen matrix and other culture systems. A plasmid lentiviral vector-GFP (pLV-GFP) was utilized for gene delivery to produce primary human foreskin fibroblasts (HFFs) that stably express GFP. Cell morphology, cell migration, and collagen contraction were compared between nontransduced HFFs and transduced GFP-HFFs; no differences were observed. Immunocytochemical staining showed no differences in cell morphology between nontransduced and GFP-HFFs in both two-dimensional and three-dimensional culture systems. Furthermore, there was no significant difference in cellular population growth within the collagen matrix populated with nontransduced vs. GFP-HFFs. Within the limits of our assays, we conclude that transduction of GFP into HFFs did not alter the observed properties of HFFs compared with nontransduced fibroblasts. The GFP-HFFs may represent a new tool for the convenient monitoring of living primary fibroblast processes in two-dimensional or three-dimensional culture.

The rat as an animal model in chronic wound research: An update.

The increasing global prevalence of chronic wounds underscores the growing importance of developing effective animal models for their study. This review offers a critical evaluation of the strengths and limitations of rat models frequently employed in chronic wound research and proposes potential improvements. It explores these models in the context of key comorbidities, including diabetes, venous and arterial insufficiency, pressure-induced blood flow obstruction, and infections. Additionally, the review examines important wound factors including age, sex, smoking, and the impact of anesthetic and analgesic drugs, acknowledging their substantial effects on research outcomes. A thorough understanding of these variables is crucial for refining animal models and can provide valuable insights for future research endeavors.

Injectable and rapidly expandable thrombin-decorated cryogels achieve rapid hemostasis and high survival rates in a swine model of lethal junctional hemorrhage.

Effective therapies are urgently needed to stabilize patients with marginally compressible junctional hemorrhage long enough to get them to the hospital alive. Herein, we report injectable and rapidly expandable cryogels consisting of polyacrylamide and thrombin (AT cryogels) created by cryo-polymerization for the efficient management of lethal junctional hemorrhage in swine. The produced cryogels have small pore sizes and highly interconnected porous architecture with robust mechanical strength. The cryogels exhibit rapid shape memory properties and prove to be resilient against fatigue. These cryogels also show high water/blood absorption capacity, fast blood clotting effect, and enhanced adhesion of red blood cells and platelets in vitro. Further, in vivo, hemostatic efficacy tests in a lethal swine junctional hemorrhage model suggest that treatment with AT cryogels, especially AT-2 cryogels, achieves the least blood loss and the highest survival rate (100 %) compared to currently employed products such as XStat® and combat gauze. The high hemostatic performance of the cryogels may be attributed to highly interconnected porous architecture with small pore size and the use of thrombin as a pro-coagulant agent. Collectively, injectable and rapidly expandable thrombin-decorated polyacrylamide-based cryogels show significant promise as hemostatic material, offering effective management of marginally compressible junctional hemorrhages in prehospital settings.