Collagen Fraction Research Articles

Sex differences in the substrate of atrial fibrillation and the outcome of thoracoscopic ablation

Abstract Background Women with atrial fibrillation (AF) suffer more from AF symptoms, a lower quality of life, and have an enhanced risk of stroke. The AF recurrence after ablation is higher in women than in men. We hypothesize that sex specific differences in the atrial fibrotic substrate underlie these differences in clinical outcome. Here, we sought to characterize atrial fibrosis and fibrosis formation in the left atrial appendage (LAA) of women and men undergoing thoracoscopic ablation of AF. Methods We used the excised LAA of 30 female and 30 male patients with persistent AF undergoing thoracoscopic AF ablation. Patients were matched for age. In addition propensity score matching was also conducted for adjusting intermediary variables such as AF duration, Age ≥ 75, Body mass index (BMI), and CHA2DS2-VASc score ≥ 4. LAAs were stained with picrosirius red to quantify collagen and with vimentin for fibroblasts. Images were analyzed automatically (Image J version 1.50i) using color deconvolution to identify the area fraction of collagen and fibroblast. Results Women had similar age as men (66.4±7.76 vs 66.1 ±7.57, P= 0.85) but had a trend toward more cardiovascular risk factors [CHA2DS2-VASc score ≥ 4, (23.3 vs 6.7)%, P=0.07]. The total percentage of fibroblasts was larger in women 14.98 (9.79-24.95) % than men 13 (5.85-17.46) %, P=.018. In addition, in women fibroblasts were located more in epicardially and endocardially than in the interstitium.[women 8.18 (5.06-13.36) % vs men 6.49 (2.73-9.92) % , P=0.005].There was not a remarkable differences in total amount of collagen between the groups [women 16.03 (9.67-26.98) % vs men 15.50 (9.50-20.90) %, P=0.57 ], but there was a trend towards more epicardial and endocardial collagen in women than men [11.81(5.75-22.11)% vs 10.24 (6.06-15.10) % , P=0.06]. Conclusion We demonstrate more epicardial and endocardial fibroblasts in the LAA of women compared to men with persistent AF. There was similarly a trend towards more epicardia and endocardial but not interstitial collagen deposition. These findings may –at least in part- underlie sex specific differences in AF pathophysiology and ablation outcome.

High-intensity interval training improves cardiomyocyte contractile function and myofilament sensitivity to intracellular Ca2+ in obese rats.

High-intensity interval training (HIIT) has shown significant results in addressing adiposity and risk factors associated with obesity. However, there are no studies that investigate the effects of HIIT on contractility and intracellular Ca2+ handling. The purpose of this study was to explore the impact of HIIT on cardiomyocyte contractile function and intracellular Ca2+ handling in rats in which obesity was induced by a saturated high-fat diet (HFD). Male Wistar rats were initially randomized into a standard diet and a HFD group. The experimental protocol spanned 23weeks, comprising the induction and maintenance of obesity (15weeks) followed by HIIT treatment (8weeks). Performance was assessed using the maximum oxygen consumption test ( ). Evaluation encompassed cardiac, adipose and skeletal muscle histology, as well as contractility and intracellular Ca2+ handling. HIIT resulted in a reduction in visceral area, an increase in , and an augmentation of gastrocnemius fibre diameter in obese subjects. Additionally, HIIT led to a decrease in collagen fraction, an increase in percentage shortening, and a reduction in systolic Ca2+/percentage shortening and systolic Ca2+/maximum shortening rates. HIIT induces physiological cardiac remodelling, enhancing the contractile function of cardiomyocytes and improving myofilament sensitivity to Ca2+ in the context of obesity. This approach not only enhances cardiorespiratory and physical performance but also reduces visceral area and prevents interstitial fibrosis.

Comparative analysis of the physical and chemical properties of dried products "KalmaKS" from the skin of the Commander and Pacific squid

The modern system of high-quality nutrition for the population includes the use of natural compounds from secondary products of animal origin. In the course of scientific substantiation of using secondary products from the processing of cephalopods, dried products from the skin of Pacific (Todarodes pacificus) and Commander squid (Berryteuthis magister) have been studied, their protein and amino acid composition and functional and technological characteristics have been analyzed. In samples from the skin of the Pacific squid, a high content of glutamic and aspartic acids (8–10 %) is noted; in samples from the skin of the Commander squid – glycine (20 %), proline (10 %) and arginine. High indicators of solubility, water-holding capacity and stability of foam structures are due to the significant content of type I destructured collagen (in a sample from the skin of Commander squid), and hydrophilic amino acids and type III collagen fragments (in a product made from Pacific squid skin). Infrared drying of products promotes denaturation and gelatinization of collagen in the skin of Commander squid, which is confirmed by the brighter color characteristics of the samples and high moisture-binding capacity when the temperature rises to 40 and 60 °C; this fact indicates an increase in the hydrophilic properties of the products of destruction of collagen fractions. Products made from skin, which is a secondary product of squid processing, have high potential for use in the food industry as water-retaining, fat-binding, and fat-emulsifying components.

O70 INVOLVEMENT OF MICRORNAs-146a-5P, -155-5P, AND -29b-5P IN CARDIAC REMODELLING AND DYSFUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS

Background: MicroRNAs have been implicated in the pathogenesis of cardiovascular disease. However, the contribution of microRNAs remain poorly understood in the context of hypertensive cardiac pathology. Aim: We investigated the role of miR-146a-5p, -155-5p, and -29b-5p in the development of cardiac hypertrophy and dysfunction in male and female spontaneously hypertensive rats (SHR). Methods: Seven (7)-month-old SHR (n=7 male, n=10 female), and age- and sex-matched normotensive Wistar Kyoto rats (WKY, n=7 male, n=9 female) were used for the study. Cardiac geometry and function were determined from echocardiography. Plasma levels of inflammatory markers were measured by ELISA. Collagen fraction area was determined from histological sections of the left ventricle (LV). MicroRNA, and mRNA expression of target genes was determined in the LV by RT-qPCR. Group differences were ascertained from 2-way ANOVA. Associations were determined from pearson's correlation. Results: In SHR, normalised heart and LV masses, LVPWTd, RWT, E, A, E/e’, and collagen fraction area were significantly greater compared to WKY. MidFS, e’, and a’ were significantly lower in SHR versus WKY. Female rats exhibited significantly greater LV mRNA expression of Lox1, Col1a/Col3a ratio, and plasma levels of CRP, IL-6, and TNF-α compared to males. MiR-29b-5p showed similar expression levels across experimental groups. MiR-146a-5p was upregulated in SHR and exhibited positive associations with BP, normalised heart and LV masses, RWT, collagen fraction area, and E/e’ ratio, but negative associations with e’. Conversely, miR-155-5p was downregulated in females and only positively associated with absolute heart, LV, kidney masses, and stroke volume. Conclusion: Upregulation of miR-146a-5p was associated with indices of concentric LVH, diastolic dysfunction, reactive fibrosis, and may be involved in the hypertensive-induced LV remodelling; whereas, changes in expression of miR-155-5p may be involved with a cardiac phenotype related to sexual dimorphism.

Development and validation of a CT-based radiomics model to predict survival-graded fibrosis in pancreatic ductal adenocarcinoma.

Tumor fibrosis plays an important role in chemotherapy resistance in pancreatic ductal adenocarcinoma (PDAC), however there remains a contradiction in the prognostic value of fibrosis. We aimed to investigate the relationship between tumor fibrosis and survival in patients with PDAC, classify patients into high- and low-fibrosis groups, and develop and validate a CT-based radiomics model to non-invasively predict fibrosis before treatment. This retrospective, bicentric study included 295 patients with PDAC without any treatments before surgery. Tumor fibrosis was assessed using the collagen fraction (CF). Cox regression analysis was used to evaluate the associations of CF with overall survival (OS) and disease-free survival (DFS). Receiver operating characteristic (ROC) analyses were used to determine the rounded threshold of CF. An integrated model (IM) was developed by incorporating selected radiomic features and clinical-radiological characteristics. The predictive performance was validated in the test cohort (Center 2). The CFs were 38.22±6.89% and 38.44±8.66% in center 1 (131 patients, 83 males) and center 2 (164 patients, 100 males), respectively (P=0.814). Multivariable Cox regression revealed that CF was an independent risk factor in the OS and DFS analyses at both centers. ROCs revealed that 40% was the rounded cut-off value of CF. IM predicted CF with areas under the curves (AUCs) of 0.825 (95% confidence interval [CI], 0.749-0.886) and 0.745 (95% CI, 0.671-0.810) in the training and test cohorts, respectively. Decision curve analyses revealed that IM outperformed radiomics model and clinical-radiological model for CF prediction in both cohorts. Tumor fibrosis was an independent risk factor for survival of patients with PDAC, and a rounded cut-off value of 40% provided a good differentiation of patient prognosis. The model combining CT-based radiomics and clinical-radiological features can satisfactorily predict survival-grade fibrosis in patients with PDAC.

Combining antibiotic-loaded bone cement-based free vastus lateralis muscle-sparing flap with split-thickness skin grafts: A reliable strategy for reconstructing diabetic foot ulcers at non-weight-bearing areas.

Diabetic foot ulcers (DFUs) present significant challenges due to their associated amputation rates, mortality, treatment complexity and excessive costs. Our earlier work introduced a wound surgical integrated treatment (WSIT) for DFUs, yielding promising outcomes. This study focuses on a specific WSIT protocol employing antibiotic-loaded bone cement (ALBC) in the first Stage, and free vastus lateralis muscle-sparing (VLMS) flaps and split-thickness skin grafts (STSGs) in the second stage to repair non-weight-bearing DFUs. From July 2021 to July 2023, seven DFU patients (aged 47-71 years) underwent this treatment. Demographic data, hospital stay and repair surgery times were collected. Histological and immunohistochemical analyses assessed angiogenesis, collagen deposition and inflammation. SF-36 questionnaire measured pre- and postoperative quality of life. Preoperative ultrasound Doppler showed that the peak blood flow velocity of the recipient area artery was significantly >30 cm/s (38.6 ± 6.8 cm/s) in all patients. Muscle flap sizes varied from 8 × 3.5 × 1 to 18 × 6 × 2 cm. The operation time of the repair surgery was 156.9 ± 15.08 minutes, and the hospital stay was 18.9 ± 3.3 days. Histological analysis proved that covering DFUs with ALBC induced membrane formation and increased collagen, neovascularization and M2 macrophages fraction while reducing M1 macrophages one. All grafts survived without amputation during a 7- to 24-month follow-up, during which SF-36 scores significantly improved. A combination of ALBC with free VLMS flaps and STSGs proved to be safe and effective for reconstructing non-weight-bearing DFUs. It rapidly controlled infection, enhanced life quality and foot function, and reduced hospitalization time. We advocate integrating this strategy into DFU treatment plans.

Targeting Interactions between Fibroblasts and Macrophages to Treat Cardiac Fibrosis.

Excessive extracellular matrix (ECM) deposition is a defining feature of cardiac fibrosis. Most notably, it is characterized by a significant change in the concentration and volume fraction of collagen I, a disproportionate deposition of collagen subtypes, and a disturbed ECM network arrangement, which directly affect the systolic and diastolic functions of the heart. Immune cells that reside within or infiltrate the myocardium, including macrophages, play important roles in fibroblast activation and consequent ECM remodeling. Through both direct and indirect connections to fibroblasts, monocyte-derived macrophages and resident cardiac macrophages play complex, bidirectional, regulatory roles in cardiac fibrosis. In this review, we discuss emerging interactions between fibroblasts and macrophages in physiology and pathologic conditions, providing insights for future research aimed at targeting macrophages to combat cardiac fibrosis.

Abstract 5571: Collagen stabilization directs immune suppression in the head and neck squamous cell carcinoma hypoxic subtype

Abstract Head & neck squamous cell carcinoma (HNSCC) show limited clinical benefit to immune checkpoint inhibitors (ICI). Interactions between extracellular matrix (ECM), tumor, and immune cells underly the mechanisms leading to immunosuppression and resistance to ICIs. Collagen matrix remodeling within tumor stroma can influence accessibility and function of immune cells. Specifically, telopeptidyl lysine residues in fibrillar collagen can be hydroxylated by Lysyl hydroxylase 2 (LH2) prior to cross-linking which leads to stiffened, stable collagen. We previously showed that this LH2-modified tumor microenvironment (TME) drives HNSCC invasion and metastasis. Here, we elucidate the interplay between LH2-modified collagen and the immune landscape within TME of hypoxic and immunosuppressive HNSCC. Bioinformatics analyses of RNAseq datasets were performed to assess pathways regulating collagen deposition and stabilization. Tissue microarray having 81 primary, 28 recurrent primary, and 3 lymph node metastases tumor cores was analyzed. Cores were classified according to our published Hypoxia-Immune signature (Chaudhary R. et al. 2023, Can Res Comm). We performed Second Harmonic Generation imaging of H&E stained TMA section to analyze the orientation and length of collagen fibrils. Picrosirius red (PSR) staining allowed quantification of total collagen and collagen maturation was assessed by polarized light imaging of birefringence. Further, we performed multiplex immunofluorescence staining for CD3+ (T-cell); CD14+ (Monocyte & Macrophage); CD11c+ (Dendritic); Pax5+ (B-cell); Pan-Cytokeratin+ (tumor), and LH2. Low (0-1) LH2 expression was seen in 29.5% of analyzed cores whereas 70.5% of cores scored high (2-3) for LH2 expression. Cores classified under the hypoxia subtype exhibit high LH2 and enrichment of collagen stability signature. Late-stage tumors have highly oriented collagen fibers compared to normal tissue or early-stage tumors which have randomly distributed fibers. CT-Fire-based measurements revealed that LH2hi cores have significantly increased fiber length and lower coefficient of variance for fiber angles. The area of collagen measured by PSR staining had no correlation with tumor stage or subtype indicating that collagen deposition is similarly high in HNSCCs. However, birefringence measurements showed that a higher fraction of mature fibrillar collagen is associated with late-stage LH2hi tumors. Interestingly, LH2 expression positively correlated with increased CD3+ T cells in stroma suggesting that anti-tumor T cells are physically obstructed by the presence of LH2-stabilized and stiffened collagen fibers. LH2 expression influences the quality of collagen but not the quantity. Understanding the effect of LH2-mediated collagen modifications on the TIME may have implications for therapeutic strategies to enhance anti-tumor immune response in HNSCC. Citation Format: Sonal Srivastava, John Powers, Ritu Chaudhary, Sadegh Marzban, Robbert J. Slebos, Jeffrey West, Xiaofei Song, Jose A. Guevara-Patino, Christine H. Chung, Antonio L. Amelio. Collagen stabilization directs immune suppression in the head and neck squamous cell carcinoma hypoxic subtype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5571.

Meat qualities of crossbred young pigs

Relevance. Interbreeding and hybridization are important factors in increasing pig productivity. As a result of the heterosis effect, the multiplicity of sows increases, the safety of offspring increases, the growth rate of young animals improves, the quality of meat improves and, as a result, the profitability of the pig industry increases.The paper presents an assessment of the meat qualities of local young pigs obtained as a result of industrial three-breed crossing.Methods. To implement the scientific and economic experience, three groups of sows of pairs of analogues of a large white breed from the Hypor company (KB Hypor) were formed. Sows of the 1st group were crossed with boars of the Landrace breed from the PIC company (Landrace Pic), the 2nd — with boars of the Landrace breed from the Genesus Genetics company (Landrace Genesus), the 3rd — with boars of the Landrace breed from the Hypor company (Landrace Hypor). As a result, two-breed crossbreeds (F1) were obtained. Next, crossbred sows (F1) of the 1st, 2nd and 3rd experimental groups were crossed with boars of the Duroc breed from Genesus Genetics, as a result, commercial young (F2) were obtained.Results. According to the research results, it was found that the highest pre-slaughter live weight was obtained from animals of the 1st group (125.12 kg), which is more than in the 2nd and 3rd experimental groups, respectively, by 5.8% and 4.0%. Studies of the chemical composition of the longest back muscle of young pigs showed that the protein content in all meat samples was in the range of 23–24% with a minimum value (23.31%) in the muscle tissue of animals of the 3rd experimental group, and the maximum (23.7%) in the 1st experimental group (the difference was 0.39%). The amount of intramuscular fat in the meat of animals of the 1st (5.57%) and 2nd (6.30%) groups was significantly higher by 1.23% and 1.96%, respectively, compared with analogues of the 3rd group. The minimum pH level of meat was noted in the 1st experimental group (5.51 pH units), the maximum — in the 2nd experimental group (5.56 pH units), the difference was 0.05 pH units. The largest mass fraction of collagen (1.11%) was obtained in the 3rd group, the smallest — in the 1st experimental group (0.66%), the difference was 0.45%.

The role of preoperative MRI in endoscopic transnasal transsphenoidal hypophysectomy of pituitary adenoma.

The trans-sphenoidal approach, commonly used for removing pituitary adenomas, has become a widely accepted and successful method. In recent years, the endoscopic trans-sphenoidal technique has emerged as a minimally invasive surgical approach for pituitary adenoma removal. The majority of pituitary adenomas exhibit a soft consistency and can be successfully extracted with aspiration and curettage using the trans-sphenoidal approach. However, a subset of around 5-15% of these adenomas possess a solid and fibrous texture. The occurrence of firm and fibrous adenomas is relatively common; unfortunately, there are no reliable predictors to identify them preoperatively. The ability to forecast the reliability of magnetic resonance imaging (MRI) holds promise for improving prior preparation and impacts the extent of resection. A cross-sectional analysis of the investigation of magnetic resonance imaging (MRI) in relation to cancer histology was performed on 68 patients who had endoscopic trans-nasal excision for nonfunctional adenomas. The determination of an intensity ratio was performed by employing quantitative estimates of MRI signal intensity obtained from both the adenoma and pons. During the surgical procedure, a series of sequential-graded procedures were used for the removal of tumours with varying consistencies. Softer tumours were addressed using the Suction technique (R1), while tumours of intermediate consistency were treated using curettes (R2). In order to evaluate the fibrotic content of firmer tumours, the utilization of Cavitron Ultrasound Surgical Aspirator(CUSA), and/or other micro-instruments (R3) was employed, with the histologic collagen fraction being quantified. In order to investigate and analyse the data, a statistical analysis was conducted. A predictive relationship between resection category and both intensity ratio, and collagen percentage was noted. The primary objective of this study was to determine the appropriate cutoff criteria for clinical utilization, as well as to investigate the association between intensity ratios and collagen percentage. Tumors with ratios ≤ 1.6 on the T2-weighted image and collagen content > 5.3% required more meticulous and sharp dissection for resection. The utilization of MRI analysis may offer some assistance, but not conclusive, in the prediction of tumour consistency.

Comparison of Histological Skin Changes After Massive Weight Loss in Post-bariatric and Non-bariatric Patients.

Changes in the skin structure, including the collagen and elastin content, have been reported with massive weight loss (MWL) following bariatric metabolic surgery (BMS) and have been correlated to a higher risk of complications after body-contouring surgery (BCS). This study aimed at comparing the histological characteristics of the skin of patients having surgical MWL (SMWL) post-BMS to those with non-surgical massive weight loss (NSMWL). This prospective study compared the epidermal thickness, and collagen and elastin fibers content in 80 skin biopsies obtained from BCS procedures performed to patients who experienced MWL defined more than 50% of excess weight loss (%EWL) either SMWL (40 biopsies) or NSMWL (40 biopsies). Twenty biopsies in each group were obtained from abdominoplasties and 20 from breast reductions. Epidermal thickness was measured in H&E-stained sections, collagen fibers were assessed using Masson trichrome-stained sections, and elastin fibers were assessed using Modified Verhoeff's stained sections. Image analysis software was used to calculate the fractions of collagen and elastin fibers. This study included 77 patients, 38 SMWL patients, and 39 NSMWL patients. The SMWL group had a significantly higher age (p < 0.001), a longer time interval from intervention (p < 0.001), higher initial weight (p < 0.001), higher initial BMI (p < 0.001), lower current weight (p = 0.005), lower current BMI (p < 0.001), and significantly higher %EWL than NSMWL group (p < 0.001). No significant differences were detected between the two groups regarding complications after abdominoplasty (p = 1.000). The elastic fibers content in the dermis was significantly higher in the abdominal region of the NSMWL group than SMWL (p = 0.029). All other parameters showed non-significant differences between NSMWL and SMWL in the skin of abdomen and breast. The SMWL group had a significant reduction in elastic fiber content in the skin of the abdomen compared to the NSMWL group. The collagen content was equally reduced in both groups with non-significant differences in both breast and abdomen regions in both groups.

Green Extraction and Preliminary Biological Activity of Hydrolyzed Collagen Peptides (HCPs) Obtained from Whole Undersized Unwanted Catches (Mugil cephalus L.).

Considering the global increase in fish consumption, the growing side-streams coming from the fish supply chain (e.g., skin, fins, tail, heads…), also including undersized or "unwanted catches", have been recently proposed as source of high-value bioactive compounds (e.g., peptides and fatty acids). In this case study, hydrolyzed collagen peptides (HCPs) were extracted from different parts of Mugil cephalus L. using environmentally friendly techniques such as ultrasounds and enzymatic treatments. Both a mixed biomass derived from the skin, fins, and tail, and a whole fish, were considered as starting biomass, simulating the unsorted processing side-streams and an undersized/unwanted catch, respectively. The extracted HCPs were purified in fractions (<3 KDa and >3 KDa) whose yields (about 5% and 0.04-0.3%, respectively) demonstrated the efficiency of the hydrolysis process. The extraction protocol proposed allowed us to also isolate the intermediate products, namely the lipids (about 8-10%) and the non-collagenous proteins (NCs, 16-23%), whose exploitation could be considered. Each sample was characterized using Sircol, UltraViolet-Spectra, and hydroxyproline assay, and the viability of their collagen fractions was tested on human endothelial cells. Significant effects were obtained at a fraction of <3 KDa, in particular at a concentration of 0.13 µg/mL. The T-scratch test was also performed, with positive results in all fractions tested.

Effects of SGLT2 inhibition on cardiac remodeling and heart failure development in rats with aortic stenosis

Abstract Introduction Aortic stenosis prevalence has been increasing as population ages. Currently, no medical therapies influence the natural history of aortic stenosis. Sodium glucose co-transporter 2 inhibitors (SGLT2i) have reduced heart failure hospitalization and cardiovascular mortality in heart failure patients with both reduced and preserved ejection fraction. The aim of this study was to evaluate the effects of SGLT2 inhibitor empagliflozin (EMPA) on cardiac remodeling and heart failure development in aortic stenosis rats. Methods Eighteen weeks after supra-aortic banding surgery, male Wistar rats were divided in four groups: Sham (n=15); sham + EMPA (Sham-EMPA, n=16); aortic stenosis (AS, n=27); and aortic stenosis + EMPA (AS-EMPA, n=27). Empagliflozin (10 mg/kg/day) was added to rat chow for 8 weeks. Echocardiogram was performed to evaluate cardiac structure and function. Myocardial collagen content was quantified by histology; activity of antioxidant enzymes and enzymes involved in energy metabolism was assessed by spectrophotometry. Protein expression was quantified by Western blot, and matrix metalloproteinase (MMP) activity by zymography. Statistical analysis: ANOVA and Bonferroni or Kruskal-Wallis and Dunn (p&amp;lt;0.05). Results AS-EMPA group had a lower frequency of anatomopathological heart failure features, a lower left ventricular (LV) dilatation (LV diastolic diameter: Sham 8.39±0.57; Sham-EMPA 8.25±0.38; AS 9.80±0.53; AS-EMPA 9.08±0.87 mm; LV systolic diameter: Sham 4.24±0.68; Sham-EMPA 4.19±0.57; AS 5.72±0.74; AS-EMPA 5.09±1.08 mm) and LV mass (Sham 0.85±0.11; Sham-EMPA 0.82±0.07; AS 2.19±0.27; AS-EMPA 1.76±0.34 g), and better diastolic function (isovolumetric relaxation time: Sham 28.6±2.28; Sham-EMPA 29.8±3.04; AS 18.9±2.59; AS-EMPA 22.9±5.02 ms) than AS. Systolic function was impaired in both AS and AS-EMPA compared to their respective controls and did not differ between AS-EMPA and AS. AS and AS-EMPA had larger myocyte diameter, higher interleukin-6 protein expression and lower catalase activity than Sham and Sham-EMPA, respectively. AS and AS-EMPA groups had lower enzyme activity from energy metabolism than their respective controls. AS presented higher lipid hydroperoxide concentration, collagen III and p65 NF-kB protein expression, and lower glutathione peroxidase activity than Sham. AS-EMPA had higher collagen I expression and inactive MMP-2 than Sham-EMPA. AS-EMPA presented higher glutathione peroxidase and intermediary active MMP-2, and lower interstitial collagen fraction (Sham 2.68±0.59; Sham-EMPA 3.16±0.33; AS 5.68±0.97; AS-EMPA 3.55±0.70 %) than AS. Conclusion Empagliflozin improves cardiac remodeling, diastolic function and myocardial oxidative stress, and reduces heart failure feature frequency and interstitial collagen fraction in aortic stenosis rats.

Delamination Strength and Elastin Interlaminar Fibers Decrease with the Development of Aortic Dissection in Model Rats.

Aortic dissection (AD) is a life-threatening tear of the vascular tissue with creation of a false lumen. To explore the mechanism underlying this tissue tear, this study investigated the delamination strength of AD model rats and the histological composition of the aorta at various stages of AD development. SD rats were administrated beta-amino propionitrile for 0 (Control), 3 (Pre-dissection), and 6 (Dissection) weeks. The thoracic aorta was harvested at 10-11 weeks of age. The Dissection group exclusively showed AD at the ascending aorta. The delamination strength, a force that separates the aorta in the radial direction, of the descending aorta decreased significantly in the order of the Control, Pre-dissection, and Dissection groups. A quantitative histological analysis of the aortic tissue demonstrated that, compared with the Control group, the area fraction of collagen was significantly higher in the Pre-dissection and Dissection groups and that of elastin was significantly lower in the Dissection group. The area fraction of the elastin fibers between the elastic laminas (interlaminar fibers) was significantly decreased in the order of the Control, Pre-dissection, and Dissection groups. Histological changes of the aortic tissue, perhaps a reduction in interlaminar fibers mainly aligned in the radial direction, decreased delamination strength, thereby causing AD.

Quercetin and its derivatives for wound healing in rats/mice: Evidence from animal studies and insight into molecular mechanisms.

Aimed to clarify the effect of quercetin and its derivatives on wound healing in animal experiments. PubMed, Embase, Science Direct, Web of Science, SinoMed, Vip Journal Integration Platform, China National Knowledge Infrastructure and WanFang databases were searched for animal experiments investigating the effect of quercetin and its derivatives on wound healing to April 2023. The Review Manager 5.4 software was used to conduct meta-analysis. Eighteen studies were enrolled in this article. According to the SYRCLE's RoB tool assessment, these studies exposed relatively low methodological quality. It was shown that animals with cutaneous wound receiving quercetin had faster wound healing in wound closure (%) than the control group. Moreover, the difference in efficacy gradually emerged after third day (WMD = 7.13 [5.52, 8.74]), with a peak reached on the tenth day after wounding (WMD = 19.78 [17.82, 21.74]). Subgroup analysis revealed that quercetin for wound closure (%) was independent of the types of rats and mice, wound area and with or without diabetes. Clear conclusion was also shown regarding the external application of quercetin for wound healing (WMD = 17.77 [11.11, 24.43]). A significant reduction in the distribution of inflammatory cells occurred in the quercetin group. Quercetin could increase blood vessel density (WMD = 1.85 [0.68, -3.02]), fibroblast distribution and collagen fraction. Biochemical indicators, including IL-1β, IL-10, TNF-α, TGF-β, vascular endothelial growth factor (VEGF), hydroxyproline and alpha-smooth muscle actin (α-SMA), had the consistent results. Quercetin and its derivatives could promote the recovery of cutaneous wound in animals, through inhibiting inflammatory response and accelerating angiogenesis, proliferation of fibroblast and collagen deposition.

Generation of Connective Tissue-Free Microvascular Fragment Isolates from Subcutaneous Fat Tissue of Obese Mice

BACKGROUND:Microvascular fragment (MVF) isolates are generated by short-term enzymatic digestion of adipose tissue and contain numerous vessel segments for the vascularization of tissue defects. Recent findings indicate that the functionality of these isolates is determined by the quality of the fat source. Therefore, we compared MVF isolates from subcutaneous adipose tissue of obese and lean mice.METHODS:MVF isolates were generated from subcutaneous adipose tissue of donor mice, which received a high fat or control diet for 12 weeks. The isolates were analyzed in vitro and in vivo.RESULTS:Feeding of mice with a high fat diet induced obesity with adipocyte hypertrophy, resulting in a significantly lower collagen fraction and microvessel density within the subcutaneous fat depots when compared to lean controls. Accordingly, MVF isolates from obese mice also contained a reduced number of MVF per mL adipose tissue. However, these MVF tended to be longer and, in contrast to MVF from lean mice, were not contaminated with collagen fibers. Hence, they could be freely seeded onto collagen-glycosaminoglycan scaffolds, whereas MVF from lean controls were trapped in between large amounts of collagen fibers that clogged the pores of the scaffolds. In line with these results, scaffolds seeded with MVF isolates from obese mice exhibited a significantly improved in vivo vascularization after implantation into full-thickness skin defects.CONCLUSION:Subcutaneous adipose tissue from obese mice facilitates the generation of connective tissue-free MVF isolates. Translated to clinical conditions, these findings suggest that particularly obese patients may benefit from MVF-based vascularization strategies.

Versatile fiber-reinforced hydrogels to mimic the microstructure and mechanics of human vocal-fold upper layers

Human vocal folds are remarkable soft laryngeal structures that enable phonation due to their unique vibro-mechanical performances. These properties are tied to their specific fibrous architecture, especially in the upper layers, which comprise a gel-like composite called lamina propria. The lamina propria can withstand large and reversible deformations under various multiaxial loadings. Despite their importance, the relationships between the microstructure of vocal folds and their resulting macroscopic properties remain poorly understood. There is a need for versatile models that encompass their structural complexity while mimicking their mechanical features. In this study, we present a candidate model inspired by histological measurements of the upper layers of human vocal folds. Bi-photonic observations were used to quantify the distribution, orientation, width, and volume fraction of collagen and elastin fibers between histological layers. Using established biomaterials, polymer fiber-reinforced hydrogels were developed to replicate the fibrillar network and ground substance of native vocal fold tissue. To achieve this, jet-sprayed poly(ε-caprolactone) fibrillar mats were successfully impregnated with poly(L-lysine) dendrimers/polyethylene glycol hydrogels. The resulting composites exhibited versatile structural, physical and mechanical properties that could be customized through variations in the chemical formulation of their hydrogel matrix, the microstructural architecture of their fibrous networks (i.e., fiber diameter, orientation and volume fraction) and their assembly process. By mimicking the collagen network of the lamina propria with polymer fibers and the elastin/ground substance with the hydrogel composition, we successfully replicated the non-linear, anisotropic, and viscoelastic mechanical behavior of the vocal-fold upper layers, accounting for inter/intra-individual variations. The development of this mimetic model offers promising avenues for a better understanding of the complex mechanisms involved in voice production. Statement of significanceHuman vocal folds are outstanding vibrating soft living tissues allowing phonation. Simple physical models that take into account the histological structure of the vocal fold and recapitulate its mechanical features are scarce. As a result, the relations between tissue components, organisation and vibro-mechanical performances still remain an open question. We describe here the development and the characterization of fiber-reinforced hydrogels inspired from the vocal-fold microstructure. These systems are able to reproduce the mechanics of vocal-fold tissues upon realistic cyclic and large strains under various multi-axial loadings, thus providing a mimetic model to further understand the impact of the fibrous network microstructure in phonation.

COMPARING BIOAPATITE AND COLLAGEN RADIOCARBON DATES FROM A 16TH CENTURY CEMETERY CONTEXT—EL JAPÓN, XOCHIMILCO, MEXICO CITY

ABSTRACT El Japón is a 16th century hamlet site in the marshlands of the southern Basin of Mexico in central Mesoamerica. Radiocarbon (14C) dating and OxCal modeling of human bone collagen (n = 11) identifies a range of burials at El Japón cemetery from 1550–1650 cal. CE. The refined chronology identifies use of this rural settlement well after the onset of colonial government-sponsored relocation of Indigenous people to larger settlements (congregaciones). Historically documented information in this work supports chronological modeling beyond stand-alone calibration. Stable isotopic study of bone samples demonstrates similar sources of dietary protein and carbohydrates. The similarity of carbon sources for bone apatite (bioapatite) and collagen offers security that both bone fractions are viable 14C dating opportunities. Recent extension of this work examines bioapatite 14C dates (n = 5) from the same bone samples when quality parameters are met—atomic carbon-nitrogen ratios of 3.2–3.3 and collagen yield of 10–20%. No significant difference is found between collagen and bioapatite dates of the same individuals (p = 0.17, Mann-Whitney U test). 14C dates from human bone samples in this primarily terrestrial dietary context can be successfully acquired from either collagen or bioapatite fractions.

Interrelation of radiocarbon ages from bone fractions in the Brazilian Intertropical Region

AbstractThere is a consensus in the literature that radiocarbon dating performed on bioapatite often produces ages younger than dating performed on collagen. We propose a general regression that could be used to convert the bioapatite radiocarbon ages to the simulated ages on collagen in fossil samples worldwide. This general regression presents several good indices of quality, high correlation (R2 = 0.98), lower values of percent predicted error (%PE = 0.01), and standard error of the estimate (%SEE = 21.83), showing that it is a good tool, as the predicted values are similar to those observed. Using this regression, we converted the radiocarbon ages of bioapatite to the expected age from the collagen fraction made for several taxa from the Brazilian Intertropical Region (BIR) and suggest that these dates could be 1–7 cal ka BP older than previously thought.

Effects of Creatine Supplementation on the Myostatin Pathway and Myosin Heavy Chain Isoforms in Different Skeletal Muscles of Resistance-Trained Rats

Creatine has been used to maximize resistance training effects on skeletal muscles, including muscle hypertrophy and fiber type changes. This study aimed to evaluate the impact of creatine supplementation on the myostatin pathway and myosin heavy chain (MyHC) isoforms in the slow- and fast-twitch muscles of resistance-trained rats. Twenty-eight male Wistar rats were divided into four groups: a sedentary control (Cc), sedentary creatine supplementation (Cr), resistance training (Tc), and resistance training combined with creatine supplementation (Tcr). Cc and Tc received standard commercial chow; Cr and Tcr received a 2% creatine-supplemented diet. Tc and Tcr performed a resistance training protocol on a ladder for 12 weeks. Morphology, MyHC isoforms, myostatin, follistatin, and ActRIIB protein expressions were analyzed in soleus and white gastrocnemius portion samples. The results were analyzed using two-way ANOVA and Tukey’s test. Tc and Tcr exhibited higher performance than their control counterparts. Resistance training increased the ratio between muscle and body weight, the cross-sectional area, as well as the interstitial collagen fraction. Resistance training alone increased MyHC IIx and follistatin while reducing myostatin (p &lt; 0.001) and ActRIIB (p = 0.040) expressions in the gastrocnemius. Resistance training induced skeletal muscle hypertrophy and interstitial remodeling, which are more evident in the gastrocnemius muscle. The effects were not impacted by creatine supplementation.