Distribution Of Collagen Fibers Research Articles

Assembly of collagen fibers into contiguous dense and loose regions of subcutaneous fascia

ABSTRACT Objective This study aimed to investigate the collagen fiber structure of the subcutaneous fascia, a connective tissue layer between the skin and epimysium. Methods Fascia samples with varying extensibility were examined using biochemical and microscopic methods Results Loose fascia, the more extensibletype, displayed sparsely distributed collagen fibers, while dense fascia showed tightly packed collagen fiber bundles. Elastase treatment, after urea pretreatment, caused the loosening of collagen fiber bundles and increased collagen fiber generation as the treatment time increased. This suggests that elastic fibers contribute to collagen fiber bundle formation. Additionally, elastase treatment stretched the fascia, indicating the presence of twodimensional tensile stress generated by elastic fibers. Either enzymes capable of cleaving elastic fibers may be activated or the stretching of elastic fibers accompanying tissue deformationmay increase the enzyme sensitivity to elastic fibers, leading to the formation of localized collagen fibers in vivo. Tissue staining confirmed that loose and dense fascia corresponded to areas with sparse and dense collagen fibers, respectively. Some dense collagen fibers appeared to migrate and disperse into loose areas. Conclusion These findings provide insights into the structural organization and functional significance of collagen fibers within the subcutaneous fascia. They particularly highlight the role of elastic fibers in maintaining tissue integrity and facilitating dynamic remodeling.

АНАТОМО-ГИСТОЛОГИЧЕСКИЕ ОСОБЕННОСТИ РЕГИОНАРНЫХ ЛИМФАТИЧЕСКИХ УЗЛОВ ЖЕЛУДКА У СОБАК

The paper describes the local features of the regional lymph nodes of the stomach in dogs. Research was carried out at the Khakass State University named after N.F. Katanov (Republic of Khakassia) on autopsy and biopsy material obtained from 34 male and female healthy outbred dogs aged 2 to 6 years. In the course of the study, the methods of intratissue injection of the lymphatic bed with colored dyes, preparation, making stained total preparations from the capsule of the lymph nodes, histological sections, light and electron microscopy were used. The regional lymph nodes of the stomach in dogs are gastric, pancreaticoduodenal, splenic, and hepatic lymph nodes. Regional lymph nodes of the stomach in dogs have a typical structure for these organs. The contractility of the capsule of the lymph nodes is determined by the quantitative and spatial distribution of smooth myocytes of its middle layer, which have local features. In the zone of muscle strands, myocytes lay in strands in several layers and were oriented along the course of attachment of the trabeculae. In the rarefaction zone, myocytes lay singly or in bundles of 2–3 cells and oriented in different directions, intersecting with each other. The depositing ability of the capsule of the lymph nodes of the stomach in dogs also has local features and is determined by the quantitative and spatial distribution of collagen and elastic fibers, as well as the presence of "reserve" folds in them. The largest number of myocytes and connective tissue fibers were detected in the zone of muscle-connective tissue cords, fewer myocytes and connective tissue fibers were detected in the zone of capsule rarefaction. Most myocytes were found in the capsules of the pancreas-duodenal lymph nodes, and the capsules of the hepatic lymph nodes contained a smaller number of myocytes relative to all regional gastric lymph nodes in dogs.

Promising protective treatment potential of endophytic bacterium Rhizobium aegyptiacum for ulcerative colitis in rats

Abstract Ulcerative colitis (UC) is an inflammatory condition of the intestine, resulting from an increase in oxidative stress and pro-inflammatory mediators. In this study, the extract of endophytic bacterium Rhizobium aegyptiacum was prepared for the first time using liquid chromatography-mass spectrometry (LC-MS). In addition, also for the first time, the protective potential of R. aegyptiacum was revealed using an in vivo rat model of UC. The animals were grouped into four categories: normal control (group I), R. aegyptiacum (group II), acetic acid (AA)-induced UC (group III), and R. aegyptiacum-treated AA-induced UC (group IV). In group IV, R. aegyptiacum was administered at 0.2 mg/kg daily for one week before and two weeks after the induction of UC. After sacrificing the rats on the last day of the experiment, colon tissues were collected and subjected to histological, immunohistochemical, and biochemical investigations. There was a remarkable improvement in the histological findings of the colon tissues in group IV, as revealed by hematoxylin and eosin (H&E) staining, Masson’s trichrome staining, and periodic acid-Schiff (PAS) staining. Normal mucosal surfaces covered with a straight, intact, and thin brush border were revealed. Goblet cells appeared magenta in color, and there was a significant decrease in the distribution of collagen fibers in the mucosa and submucosal connective tissues. All these findings were comparable to the respective characteristics of the control group. Regarding cyclooxygenase-2 (COX-2) immunostaining, a weak immune reaction was shown in most cells. Moreover, the colon tissues were examined using a scanning electron microscope, which confirmed the results of histological assessment. A regular polygonal unit pattern was seen with crypt orifices of different sizes and numerous goblet cells. Furthermore, the levels of catalase (CAT), myeloperoxidase (MPO), nitric oxide (NO), interleukin-6 (IL-6), and interlukin-1β (IL-1β) were determined in the colonic tissues of the different groups using colorimetric assay and enzyme-linked immunosorbent assay (ELISA). In comparison with group III, group IV exhibited a significant rise (P<0.05) in the CAT level but a substantial decline (P<0.05) in the NO, MPO, and inflammatory cytokine (IL-6 and IL-1 β) levels. Based on reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the tumor necrosis factor-α (TNF-α) gene expression was upregulated in group III, which was significantly downregulated (P<0.05) by treatment with R. aegyptiacum in group IV. On the contrary, the heme oxygenase-1 (HO-1) gene was substantially upregulated in group IV. Our findings imply that the oral consumption of R. aegyptiacum ameliorates AA-induced UC in rats by restoring and reestablishing the mucosal integrity, in addition to its anti-oxidant and anti-inflammatory effects. Accordingly, R. aegyptiacum is potentially effective and beneficial in human UC therapy, which needs to be further investigated in future work.

Distribution and Maturity of Medial Collagen Fibers in Thoracoabdominal Post-Dissection Aortic Aneurysms: A Comparative Study of Marfan and Non-Marfan Patients.

Thoracoabdominal aortic aneurysms (TAAAs) are rare but serious conditions characterized by dilation of the aorta characterized by remodeling of the vessel wall, with changes in the elastin and collagen content. Individuals with Marfan syndrome have a genetic predisposition for elastic fiber fragmentation and elastin degradation and are prone to early aneurysm formation and progression. Our objective was to analyze the medial collagen characteristics through histological, polarized light microscopy, and electron microscopy methods across the thoracic and abdominal aorta in twenty-five patients undergoing open surgical repair, including nine with Marfan syndrome. While age at surgery differed significantly between the groups, maximum aortic diameter and aneurysm extent did not. Collagen content increased from thoracic to infrarenal segments in both cohorts, with non-Marfan patients exhibiting higher collagen percentages, notably in the infrarenal aorta (729.3 nm vs. 1068.3 nm, p = 0.02). Both groups predominantly displayed mature collagen fibers, with the suprarenal segment containing the highest proportion of less mature fibers. Electron microscopy revealed comparable collagen fibril diameters across segments irrespective of Marfan status. Our findings underscore non-uniform histological patterns in TAAAs and suggest that ECM remodeling involves mature collagen deposition, albeit with lower collagen content observed in the infrarenal aorta of Marfan patients.

Development and performance validation of an affordable and portable high-resolution darkfield polarization-sensitive multispectral imaging microscope for the assessment of radiation dermatitis and fibrosis.

Radiation therapy (RT) is widely used for cancer treatment but is found with side effects of radiation dermatitis and fibrosis thereby calling for timely assessment. Nevertheless, current clinical assessment methods are found to be subjective, prone to bias, and accompanied by variability. There is, therefore, an unmet clinical need to explore a new assessment technique, ideally portable and affordable, making it accessible to less developed regions too. We developed an affordable (16764 CNY) and portable high-resolution ((3.91 μm) darkfield polarization-sensitive multispectral imaging (PS-MSI) microscope. The implementation of the Monte Carlo simulation on the PS multi spectra allows the quantitative analysis of physiological parameters (i.e., blood volume fraction (BVF) and oxygen saturation of hemoglobin) at different skin layers for the dermatitis assessment. Further derivation of the degree of linear polarization (DOLP) reflects randomly distributed collagen fibers associated with fibrosis for the fibrosis assessment. PS-MSI microscope developed revealed a significant decrease (p < 0.001, analysis of variance, ANOVA) in the DOLP associated with fibrosis like scar tissue, and significant (p < 0.001, ANOVA) increases in BVF and oxygen saturation of hemoglobin accompanying artificially induced dermatitis. One-dimensional convolutional neural network implemented on the DOLP and multiple spectra achieved accuracies of 96% and 92.2%, respectively, for the classification of the artificially induced skin dermatitis and fibrosis like scar, demonstrating the potential of the affordable PS-MSI microscope developed for objective, unbiased and consistent assessment of radiation dermatitis and fibrosis in the clinics.

Neutrophil extracellular traps, deoxyribonuclease and fibrosis in thoracic aortic aneurysm

Abstract Introduction Thoracic aortic aneurysm (TAA) is a rare but severe cardiovascular disease. The condition often goes undiagnosed, increasing the risk of acute aortic events. It is characterized by medial degeneration, caused by neutrophils infiltrating aortic tissue. Neutrophils can form proinflammatory and prothrombotic neutrophil extracellular traps (NETs), promoting disease progression. Purpose Recently, NETs and abdominal aortic aneurysm (AAA) were linked, while their effects on TAA development and progression remain unclear. We aimed to characterize NETs and NET-specific markers in tissue and plasma samples of TAA patients. Methods We included 171 patients with either ascending TAA (n=153) or Type A dissection (n=18). Healthy subjects were recruited as controls (n=135). Sample fiber composition was analyzed using trichrome; NET burden was quantified using immunofluorescence. Plasma NET surrogate markers including double-stranded (ds)DNA, myeloperoxidase (MPO), DNase activity and matrixmetalloproteinases (MMP) were measured using a fluorescence-based assay and ELISA, respectively. mRNA expression was assessed using qPCR. Results Median patient age was 65 years, and most were male (68.4%). Cardiovascular risk factors were common, including hypertension (77.8%), hyperlipidemia (57.9%), coronary artery disease (26.3%), and diabetes (18.7%). TAA patients were older with high BMI and impaired kidney function. Trichrome staining revealed abundant fibrotic material (median 47.99%), while collagen and elastic fiber distributions were 27.67% and 20.17%, respectively. TAA patients had increased amounts of aortic fibrotic material (47.99% vs 38.94%, p=0.001). Using immunofluorescence, we found higher NET expression in diseased tissue (0.87 [0.3, 1.85] vs 0.15 [0.03, 0.22]%, p=0.0017). This increase was primarily driven by the dissection patients (1.76 [0.89, 2.83]%, p=0.0037). Plasma MPO levels were increased in TAA compared to controls (36.93 [23.46, 57.55] vs 26.8 [19.7, 36.2]ng/mL, p&amp;lt;0.001), while DNase activity was decreased in patients (4.16 [2.66, 6.24] vs 6.06 [4.25, 8.11]mU/mL, p&amp;lt;0.001). Moreover, circulating plasma levels of MMP2 were elevated in TAA (250.36 [190.24, 351.32] vs 218.85 [171.32, 263.87]ng/mL, p=0.004). qPCR analysis of mRNA expressions in TAA cryospecimens revealed upregulations of TNFα (p=0.033) and CD45 (p=0.003), when compared to aortic disease-free controls. Conclusion Aortic fibrosis at the aneurysm site may be caused by inflammatory mechanisms involving TNFα and leucocytes (CD45+). High local NET-burden is indicative of activated neutrophils in the aortic media. TAA patients have suppressed DNase activity and higher MPO levels in venous blood, leading to dsDNA accumulation and increased neutrophil turnover. Elevated MMP2 suggests its involvement in TAA formation. Our findings could enable further research targeting NETs and inflammation in TAA, possibly finding novel therapies capable of mitigating aneurysm development.

Regulatory Role of Collagen XI in the Establishment of Mechanical Properties of Tendons and Ligaments in Mice Is Tissue Dependent.

Collagen XI is ubiquitous in tissues such as joint cartilage, cancellous bone, muscles, and tendons and is an important contributor during a crucial part in fibrillogenesis. The COL11A1 gene encodes one of three alpha chains of collagen XI. The present study elucidates the role of collagen XI in the establishment of mechanical properties of tendons and ligaments. We investigated the mechanical response of three tendons and one ligament tissues from wild type and a targeted mouse model null for collagen XI: Achilles tendon (ACH), the flexor digitorum longus tendon (FDL), the supraspinatus tendon (SST), and the anterior cruciate ligament (ACL). Area was substantially lower in Col11a1ΔTen/ΔTen ACH, FDL, and SST. Maximum load and maximum stress were significantly lower in Col11a1ΔTen/ΔTen ACH and FDL. Stiffness was lower in Col11a1ΔTen/ΔTen ACH, FDL, and SST. Modulus was reduced in Col11a1ΔTen/ΔTen FDL and SST (both insertion site and midsubstance). Collagen fiber distributions were more aligned under load in both wild type group and Col11a1ΔTen/ΔTen groups. Results also revealed that the effect of collagen XI knockout on collagen fiber realignment is tendon-dependent and location-dependent (insertion versus midsubstance). In summary, this study clearly shows that the regulatory role of collagen XI on tendon and ligament is tissue specific and that joint hypermobility in type II Stickler's Syndrome may in part be due to suboptimal mechanical response of the soft tissues surrounding joints.

Effect of macrophage-to-myofibroblast transition on silicosis.

The aim was to explore the effect of macrophage polarization and macrophage-to-myofibroblast transition (MMT) in silicosis. Male Wistar rats were divided into a control group and a silicosis group developed using a HOPE MED 8050 dynamic automatic dusting system. Murine macrophage MH-S cells were randomly divided into a control group and an SiO2 group. The pathological changes in lung tissue were observed using hematoxylin and eosin (HE) and Van Gieson (VG) staining. The distribution and location of macrophage marker (F4/80), M1 macrophage marker (iNOS), M2 macrophage marker (CD206), and myofibroblast marker (α-smooth muscle actin [α-SMA]) were detected using immunohistochemical and immunofluorescent staining. The expression changes in iNOS, Arg, α-SMA, vimentin, and type I collagen (Col I) were measured using Western blot. The results of HE and VG staining showed obvious silicon nodule formation and the distribution of thick collagen fibers in the lung tissue of the silicosis group. Macrophage marker F4/80 increased gradually from 8 to 32 weeks after exposure to silica. Immunohistochemical and immunofluorescent staining results revealed that there were more iNOS-positive cells and some CD206-positive cells in the lung tissue of the silicosis group at 8 weeks. More CD206-positive cells were found in the silicon nodules of the lung tissues in the silicosis group at 32 weeks. Western blot analysis showed that the expressions of Inducible nitric oxide synthase and Arg protein in the lung tissues of the silicosis group were upregulated compared with those of the control group. The results of immunofluorescence staining showed the co-expression of F4/80, α-SMA, and Col I, and CD206 and α-SMA were co-expressed in the lung tissue of the silicosis group. The extracted rat alveolar lavage fluid revealed F4/80+α-SMA+, CD206+α-SMA+, and F4/80+α-SMA+Col I+ cells using immunofluorescence staining. Similar results were also found in MH-S cells induced by SiO2. The development of silicosis is accompanied by macrophage polarization and MMT.

Second harmonic generation microscopy, biaxial mechanical tests and fiber dispersion models in human skin biomechanics

Advanced numerical simulations of the mechanical behavior of human skin require thorough calibration of the material’s constitutive models based on experimental ex vivo mechanical tests along with images of tissue microstructure for a variety of biomedical applications. In this work, a total of 14 human healthy skin samples and 4 additional scarred skin samples were experimentally analyzed to gain deep insights into the biomechanics of human skin. In particular, second harmonic generation (SHG) microscopy was used to extract detailed images of the distribution of collagen fibers, which were subsequently processed using a three-dimensional Fourier transform-based method recently proposed by the authors to quantify the distribution of fiber orientations. Mechanical tests under both biaxial and uniaxial loading were performed to calibrate the relevant mechanical parameters of two widely used constitutive models of soft fiber-reinforced biological tissues that account for non-symmetrical fiber dispersion. The calibration of the models allowed us to identify correlations between the mechanical parameters of the constitutive models considered. Statement of significanceConstitutive models for soft collagenous tissues can accurately reproduce the complex nonlinear and anisotropic mechanical behavior of skin. However, a comprehensive analysis of both microstructural and mechanical parameters is still missing for human skin. In this study, these parameters are determined by combining biaxial mechanical tests and SHG stacks of collagen fibers on ex vivo healthy human skin samples. The constitutive parameters are provided for two widely used hyperelastic models and enable accurate characterization of skin mechanical behavior for advanced numerical simulations.

Establishing Standardization Guidelines For Finite-Element Optomechanical Simulations of Refractive Laser Surgeries: An Application to Photorefractive Keratectomy.

Computational models can help clinicians plan surgeries by accounting for factors such as mechanical imbalances or testing different surgical techniques beforehand. Different levels of modeling complexity are found in the literature, and it is still not clear what aspects should be included to obtain accurate results in finite-element (FE) corneal models. This work presents a methodology to narrow down minimal requirements of modeling features to report clinical data for a refractive intervention such as PRK. A pipeline to create FE models of a refractive surgery is presented: It tests different geometries, boundary conditions, loading, and mesh size on the optomechanical simulation output. The mechanical model for the corneal tissue accounts for the collagen fiber distribution in human corneas. Both mechanical and optical outcome are analyzed for the different models. Finally, the methodology is applied to five patient-specific models to ensure accuracy. To simulate the postsurgical corneal optomechanics, our results suggest that the most precise outcome is obtained with patient-specific models with a 100 µm mesh size, sliding boundary condition at the limbus, and intraocular pressure enforced as a distributed load. A methodology for laser surgery simulation has been developed that is able to reproduce the optical target of the laser intervention while also analyzing the mechanical outcome. The lack of standardization in modeling refractive interventions leads to different simulation strategies, making difficult to compare them against other publications. This work establishes the standardization guidelines to be followed when performing optomechanical simulations of refractive interventions.

Elasticity of the Cervix in Relation to Uterus Position.

Strain elastography allows the evaluation of tissue elasticity. Background/Objectives: Tissue elasticity depends on the content and distribution of collagen fibers and is shaped by the applied tensile forces that may differ in uteri with a different angle of flexion of the corpus on the cervix. The objective was to investigate whether the angle of uterine flexion is related to cervical tissue elasticity. Methods: The anterior angle between the longitudinal axis of the uterus corpus and that of the cervix was measured in 275 non-pregnant young women by transvaginal ultrasonography and considered both as an absolute value or categorized as ≤150°, between >150° and ≤210°, and >210°. Strain elastography was used to assess tissue elasticity by placing the probe in the anterior vaginal fornix. Tissue elasticity was evaluated in the middle of the anterior cervical compartment (ACC), in the middle of the posterior cervical compartment (PCC), in the middle portion of the cervical canal (MCC), and at the internal cervical os (ICO). In a sagittal plane MCC was evaluated across the cervical canal, and ACC and PCC at a distance equal between the cervical canal and the outer anterior or posterior part of the cervix. MCC, ACC and PCC were evaluated at equal distance between the ICO and the external cervical os. Elasticity was expressed as a color score ranging from 0.1 (low elasticity) to 3 (high elasticity). Results: The angle of uterine flexion show a negative linear relation with the elasticity of the ACC (p = 0.001) and MCC (p = 0.002) and a positive relation with the elasticity of the PCC (p = 0.054). In comparison to uteri with an angle of flexion of <150°, those with an angle of flexion of >210° had lower elasticity of the ACC (p = 0.001) and MCC (p = 0.001) and higher elasticity of the PCC (p = 0.004). The ACC/PCC and PCC/MCC elasticity ratios were also significantly different (p = 0.001). Conclusions: The angle of uterine flexion is associated with changes in cervix elasticity. Retroflexion is associated with stiffer ACC and MCC and a more elastic PCC. Differences in tissue elasticity suggest structural changes of the cervix that may have implication in variate obstetric and gynecological conditions.

Effect of orlistat versus lipo-6 black on the testis of adult obese albino rats: histological and histomorphometric study

Background Obesity is a health problem with increasing incidence. Excess fat is the most common factor that contributes to its pathogenesis. Aim To evaluate the effect of obesity on the testis of male rats and compare the possible ameliorative effect of orlistat versus lipo-6. Materials and methods Fifty-six adult male rats were used. The control group ‘eight rats’ received a standard diet (SD) with no treatment for 90 days. The experimental group ‘48 rats’ received high-fat diet (HFD) for 60 days for obesity induction. Obese rats were subdivided into three groups (each group a and b). IIa received SD and IIb received HFD. IIIa received SD+orlistat and IIIb received HFD+orlistat. IVa received SD+lipo-6. IVb received HFD+lipo 6. The drugs were used for 30 days. Testicular specimens were subjected to histological, histomorphometrical, and immunohistochemical examinations. Data on obesity index, testis weight, abdominal circumference sperm percentage, and histomorphometry were analyzed statistically. Results Subgroups IIIa and IVa showed restoration of the structural integrity of the seminiferous tubules with the normal distribution of collagen fibers. Sections of subgroup IIIa showed negative caspase-3 immunostaining near the control group. Lee obesity index and percentage of abnormal sperm were close to control. Conclusion Orlistat and lipo-6 with diet adjustment reduced the severity of testicular damage induced by obesity.

Abstract 4281: BMP signaling impaired telocytes-Foxl1+disrupt the extracellular matrix network enabling the development of colitis-associated cancer

Abstract The relationship between colon stem cells (SCs), its surrounding niche microenvironment like the extracellular matrix (ECM) and the mesenchymal niche cells is complex and dynamic. ECM proteins are not only a scaffolding system for SCs, but their biophysical properties also contribute to localizing signals and creating gradients leading to the SCs homeostasis. Foxl1+-Telocytes (TCFoxL1+) are mesenchymal niche cells implicated in cell-cell communication and the production of BMP ligands. Upon chronic inflammation, mice lacking BMP signaling in TCFoxL1+ (BmpR1aΔFoxL1+), developed colonic tumors with microenvironment exhibiting abnormal TCFoxL1+ structure, increased BMP expression and myofibroblastic-like cancer-associated fibroblasts (myCAF) subpopulation. Yet, how the TCFoxL1+ influences SCs niche ECM proteins during tumorigenesis is less understood. We aimed to investigate how the loss of BMP signaling in TCFoxL1+ affects ECM network impacting the niche microenvironment promoting the development of CAC. DSS-based chronic inflammatory challenge in mutant and control mice, quantitative-MS-based strategy was performed to determine the proteome of the transformed regions solely in epithelial-mesenchymal tissue following colon deconstruction. Expression of the proteins of interest were validated by Western Blots or immunostainings. Quantitative analysis of collagen network was assessed using phyton pipeline U-net in Sirius red-stained colon analyzed under polarized light. Differential significant expression of 798 proteins, with 342 upregulated and 456 downregulated, were found in the tumors of mutant mice compared to controls. Mfap5 involved in CAF activation was the highest upregulated protein. We found upregulated, laminin subunits α4 and β2, decorin, lumican as well as transgelin (myCAF marker), which are proteins known for contributing to the stiffening of the ECM during colorectal cancer. Adamdec1 which prevents aberrant ECM accumulation and thrombospodin-1, an ECM glycoprotein whose low levels have been related to tumor growth, were both found to be downregulated. Data extracted from Python's U-Net pipeline demonstrated that tumors, in mutant mice, exhibited higher frequencies of straighter collagen fibers compared to wavier fibers in controls. Collagen fiber distribution was shown to present an even angle distribution in controls whereas BmpR1aΔFoxL1+ mice presented a preferential orientation. These results suggest that defective TCFoxL1+ commits the surrounding niche microenvironment, especially its ECM, toward the development and progression of CAC. Citation Format: Vilcy Reyes Nicolas, Alain B. Alfonso, Jennifer Raisch, François M. Boisvert, Marc-Antoine Lauzon, Nathalie Perreault. BMP signaling impaired telocytes-Foxl1+disrupt the extracellular matrix network enabling the development of colitis-associated cancer [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 4281.

The effect of caponization on tibia bone histomorphometric properties of crossbred roosters

The negative effect of caponization on the structural, geometric and mechanical parameters of femur and tibia has been shown in a few studies. Nevertheless, its influence on tibia bone microarchitecture is still largely unknown. Therefore, this study aimed to assess the effect of castration on the microstructural parameters of the trabecular and compact bone of tibia bone in crossbred chickens. The experiment involved 96 roosters derived from crossing Yellowleg Partridge hens (Z˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{\ ext{Z}}}$$\\end{document}-33) and Rhode Island Red cockerels (R-11) fattened until the 16th, 20th and 24th week of life. Animals were randomly divided into 2 groups of 48 each. Group I (control) consisted of intact roosters and group II (experimental) consisted of birds subjected to caponization at the 8th week of age. The castration surgery had no influence on some properties within compact bone such as osteon diameter On.Dm, osteon perimeter On.Pm, osteon area On.Ar, osteocyte lacunar number Ot.Lc.N, osteon bone area On.B.Ar, osteon wall thickness On.W.Th as well as thick-mature collagen content in all analyzed age groups of animals. Nevertheless, our results demonstrate that castration caused a decrease of Haversian canal area Hc.Ar, osteocyte lacunar area Ot.Lc.Ar and osteocyte lacunar porosity Ot.Lc.Po among the 16-week-old birds, decrease of Haversian canal perimeter Hc.Pm and increase of fraction of bone area On.B.Ar/On.Ar among 16- and 24-week-old individuals and also an increase of osteocyte lacunar density Ot.Lc.Dn in the osteons of the oldest roosters. Additionally, some microstructural parameters of trabecular bone show the negative effect of caponization. The youngest 16-week-old capons were characterized by thinnin the trabecular in the epiphysis part of tibia. Moreover, in the case of 24-week-old, there is an increase in the trabecular separation Tb.Sp with simultaneous decrease of trabecular number Tb.N compared to roosters, which may suggest the increase of the bone resorption among the oldest individuals. The increased bone turnover in the epiphysis part of the tibia bone also indicates changes in the collagen fibers distribution, where among 20-week-old animals there is a decrease in the content of immature thin collagen fibers with simultaneous increase in the content of mature thick collagen fibers. Furthermore, among the oldest 24-week-old individuals we can observe the increased thick-to-thin collagen ratio, which may be a sign of slowing down in bone formation.

It's more than the amount that counts: implications of collagen organization on passive muscle tissue properties revealed with micromechanical models and experiments.

Collagen accumulation is often used to characterize skeletal muscle fibrosis, but the role of collagen in passive muscle mechanics remains debated. Here we combined finite-element models and experiments to examine how collagen organization contributes to macroscopic muscle tissue properties. Tissue microstructure and mechanical properties were measured from in vitro biaxial experiments and imaging in dystrophin knockout (mdx) and wild-type (WT) diaphragm muscle. Micromechanical models of intramuscular and epimuscular extracellular matrix (ECM) regions were developed to account for complex microstructure and predict bulk properties, and directly calibrated and validated with the experiments. The models predicted that intramuscular collagen fibres align primarily in the cross-muscle fibre direction, with greater cross-muscle fibre alignment in mdx models compared with WT. Higher cross-muscle fibre stiffness was predicted in mdx models compared with WT models and differences between ECM and muscle properties were seen during cross-muscle fibre loading. Analysis of the models revealed that variation in collagen fibre distribution had a much more substantial impact on tissue stiffness than ECM area fraction. Taken together, we conclude that collagen organization explains anisotropic tissue properties observed in the diaphragm muscle and provides an explanation for the lack of correlation between collagen amount and tissue stiffness across experimental studies.

Clock gene Per2 modulates epidermal tissue repair in vivo.

Wound healing can be influenced by genes that control the circadian cycle, including Per2and BMAL1, which coordinate the functions of several organs, including the skin. The aim of the study was to evaluate the role of PER2 during experimental skin wound healing. Two groups (control and Per2-KO), consisting of 14 male mice each, were anesthetized by inhalation, and two 6 mm wounds were created on their dorsal skin using a punch biopsy. A silicone ring was sutured around the wound perimeter to restrict contraction. The wound healing process was clinically measured daily (closure index) until complete wound repair. On Day 6, histomorphometric analysis was performed using the length and thickness of the epithelial migration tongue, in addition to counting vessels underlying the lesion by immunofluorescence assay and maturation of collagen fibers through picrosirius staining. Bromodeoxyuridine(BrdU) incorporation and quantification were performed using the subcutaneous injection technique 2 h before euthanasia and through immunohistochemical analysis of the proliferative index. In addition, the qualitative analysis of myofibroblasts and periostin distribution in connective tissue was performed by immunofluorescence. Statistically significant differences were observed in the healing time between the experimental groups (means: 15.5 days for control mice and 13.5 days for Per2-KO; p = 0.001). The accelerated healing observed in the Per2-KO group (p < 0.05) was accompanied by statistical differences in wound diameter and length of the migrating epithelial tongue (p = 0.01) compared to the control group. Regarding BrdU immunoreactivity, higher expression was observed in the intact epithelium of Per2-KO animals (p = 0.01), and this difference compared to control was also present, to a lesser extent, at the wound site (p = 0.03). Immunofluorescence in the connective tissue underlying the wound showed a higher angiogenic potential in the Per2-KO group in the intact tissue area and the wound region (p < 0.01), where increased expression of myofibroblasts was also observed. Qualitative analysis revealed the distribution of periostin protein and collagen fibers in the connective tissue underlying the wound, with greater organization and maturation during the analyzed period. Our research showed that the absence of the Per2 gene positively impacts the healing time of the skin in vivo.This acceleration depends on the increase of epithelial proliferative and angiogenic capacity of cells carrying the Per2 deletion.

Special Staining and Protein Expression of VEGF/EGFR and P53/NF-κB in Cryptorchid Tissue of Erhualian Pigs.

Erhualian pigs exhibit one of the highest reproductive rates globally, and cryptorchidism is a crucial factor affecting reproductive abilities of boars. This investigation focused on cryptorchid tissues from Erhualian pigs, where the histological structure of cryptorchidism was observed using specialized staining. In addition, protein expression of P53/NF-κB in cryptorchid tissues was assessed using Western blot and immunohistochemistry. In comparison to normal Erhualian testes, Masson's trichrome staining indicated a reduction in collagen fibers in the connective tissue and around the basal membrane of the seminiferous tubules in cryptorchid testes. Moreover, collagen fiber distribution was observed to be disordered. Verhoeff Van Gieson (EVG) and argyrophilic staining demonstrated brownish-black granular nucleoli organized regions in mesenchymal cells and germ cells. When compared to normal testicles, the convoluted seminiferous tubules of cryptorchids exhibited a significantly reduced number and diameter (p < 0.01). Notably, VEGF/EGFR and P53/NF-κB expression in cryptorchidism significantly differed from that in normal testes. In particular, the expression of VEGF and P53 in cryptorchid tissues was significantly higher than that in normal testes tissues, whereas the expression of EGFR in cryptorchid tissues was significantly lower than that in normal testes tissues (all p < 0.01). NF-κB expressed no difference in both conditions. The expressions of VEGF and NF-κB were observed in the cytoplasm of testicular Leydig cells and spermatogenic cells, but they were weak in the nucleus. EGFR and P53 were more positively expressed in the cytoplasm of these cells, with no positive expression in the nucleus. Conclusion: There were changes in the tissue morphology and structure of the cryptorchid testis, coupled with abnormally high expression of VEGF and P53 proteins in Erhualian pigs. We speculate that this may be an important limiting factor to fecundity during cryptorchidism.

Molecular mechanism of triptolide in myocardial fibrosis through the Wnt/β-catenin signaling pathway

Objective. Myocardial fibrosis (MF) is a common manifestation of end-stage cardiovascular diseases. Triptolide (TP) provides protection against cardiovascular diseases. This study was to explore the functional mechanism of TP in MF rats via the Wnt/β-catenin pathway. Methods. The MF rat model was established via subcutaneous injection of isoproterenol (ISO) and treated with low/medium/high doses of TP (L-TP/M-TP/H-TP) or Wnt agonist BML-284. Cardiac function was examined by echocardiography. Pathological changes of myocardial tissues were observed by HE and Masson staining. Col-I/Col-III/Vimentin/α-SMA levels were detected by immunohistochemistry, RT-qPCR, and Western blot. Collagen volume fraction content was measured. Expression levels of the Wnt/β-catenin pathway-related proteins (β-catenin/c-myc/Cyclin D1) were detected by Western blot. Rat cardiac fibroblasts were utilized for in vitro validation experiments. Results. MF rats had enlarged left ventricle, decreased systolic and diastolic function and cardiac dysfunction, elevated collagen fiber distribution, collagen volume fraction and hydroxyproline content. Levels of Col-I/Col-III/Vimentin/α-SMA, and protein levels of β-catenin/c-myc/Cyclin D1 were increased in MF rats. The Wnt/β-catenin pathway was activated in the myocardial tissues of MF rats. TP treatment alleviated impairments of cardiac function and myocardial tissuepathological injury, decreased collagen fibers, collagen volume fraction, Col-I, Col-III, α-SMA and Vimentin levels, HYP content, inhibited Wnt/β-catenin pathway, with H-TP showing the most significant effects. Wnt agonist BML-284 antagonized the inhibitive effect of TP on MF. TP inhibited the Wnt/β-catenin pathway to repress the proliferation and differentiation of mouse cardiac fibroblasts in vitro. Conclusions. TP was found to ameliorate ISO-induced MF in rats by inhibiting the Wnt/β-catenin pathway.

Anti-Alzheimer potential of Solanum lycopersicum seeds: in vitro, in vivo, metabolomic, and computational investigations

Abstract Background Solanum lycopersicum Linn. (Tomato, Family Solanaceae) is one of the fruits that are most consumed worldwide. The current research intends to emphasise the possibility of positive and therapeutic effects of S. lycopersicum seed extract (SLSE) on Alzheimer's disease's neurodegeneration effects being reversed in a study utilising rats exposed to aluminium chloride. Investigations were done on the cholinesterase and antioxidant in vitro activity of SLSE. Rats with Alzheimer's disease were given SLSE, and donepezil (500, and 10 mg/kg.b.wt., daily for six weeks, respectively) to test SLSE biological activity. Beam-balance and T-maze tests, as well as serum levels of AChE, norepinephrine, dopamine, serotonin, IL-6, glycated end product, BDNF, MDA, TAC, and GSH were assessed, accompanied with histological investigation. To impact the effectiveness of this extract, bioinformatics study was validated. Results Crude SLSE showed in vitro DPPH scavenging and AChE inhibition activities, indicating the extract might have anti-Alzheimer potential, which was validated using an aluminium-intoxicated rat model, in vivo. In Alzheimer's rats, in vivo studies showed considerable improvements, as seen by improved beam balance, and T-maze tests and decreased serum levels of AChE, norepinephrine, dopamine, serotonin, IL-6, glycated end product, BDNF, and MDA, with increasing in TAC, and GSH levels. Brain tissue histological tests revealed a largely typical pattern of collagen fibre distribution. LC–HRESIMS metabolomic profiling of crude SLSE identified 33 compounds. Furthermore, the bioinformatics study discovered 378 targets related to the major identified compounds, of which only 133 were related to Alzheimer's and memory disorders, with APP, AChE, and PSEN2 targets which were marked as the top genes. Gene enrichment analysis identified the arachidonic acid metabolism and PPAR signalling pathway as the biological pathways enriched by all the gene sets under investigation. Conclusion As a result, the study findings are expected to pave the way for the creation of dietary supplements for Alzheimer's disease management. Graphic abstract

Effect of Long-Term Treatment with Alendronate on Bone Repair and Mineralization Around Implants in Rats

Abstract The aim of this study was to evaluate the effects of long-term alendronate administration on bone repair and mineralization around osseointegrated implants in rats. A total of 160 female Wistar rats were randomly assigned to two groups: the control group (CTL) and the alendronate group (ALD). The ALD group received a subcutaneous injection of sodium alendronate (1 mg/kg/week), while the CTL group received weekly injections of saline solution. After 120 days of treatment, a bilateral implant was placed in the tibia of each rat. Ten rats from each group were euthanized at 5, 10, 15, 20, 25, 30, 45, or 60 days post-surgery. Picro-sirius red staining was utilized to assess the distribution and arrangement of collagen fibers near the implant threads. Bone mineralization mapping of the native bone adjacent to the implant was performed using images obtained through scanning electron microscopy (SEM) across all follow-up periods. SEM-based mineralization mapping revealed an increase in both the degree and homogeneity of bone mineralization in the ALD group compared to the CTL group. Alendronate administration affected collagen arrangement and distribution, leading to a connective tissue with reduced organization and thinner collagen fiber bundles. In conclusion, the findings demonstrated that alendronate administration resulted in a higher degree and homogeneity of bone mineralization, accompanied by reduced collagen content and organization, suggesting an impairment in bone remodeling around dental implants.