Ground Substance Research Articles

Tribal Identity, Pain Interference, and Substance Use Among American Indian and Alaska Native Adolescents

Substance use is high among American Indian/Alaska Native adolescents. Pain interference is a risk factor for substance use, and identifying potential protective factors, such as Tribal identity, is important to help inform culturally grounded substance use prevention strategies. To examine the protective potential of Tribal identity as a moderator in the association between pain interference and substance use in American Indian/Alaska Native adolescents. This cross-sectional study of 10th-grade students self-identifying as American Indian/Alaska Native was conducted among students enrolled at 20 high schools on or near the Cherokee Nation Reservation. Data for this study were collected from the baseline assessments of a cluster randomized trial to prevent substance use among adolescents living on or near the Cherokee Nation Reservation. Inclusion criteria for high schools' participation included being located within counties that partially or fully fall within the Cherokee Nation reservation, a town population of 3000 individuals or fewer, and class sizes between 30 and 100 students. Exclusion criteria included high schools within metropolitan and micropolitan cores (per the US Census Bureau's Rural-Urban Commuting Area codes) and the existence of an established community drug prevention coalition. Student surveys were conducted from September 2021 to May 2024. Pain interference in the 7 days prior to baseline assessment. The primary outcomes were past 30-day alcohol use, marijuana use, and prescription opioid misuse. Generalized estimating equations Poisson models were used, with an exchangeable correlation structure clustered on the school level using baseline data from a cluster randomized trial to prevent alcohol and substance use among adolescents. For each substance, a separate multivariable model was fit, which included pain interference, Tribal identity, an interaction term between pain interference and Tribal identity, age, gender, food insecurity, anxiety symptoms, and depressive symptoms. Among 514 self-identified American Indian/Alaska Native students at 20 high schools on or near the Cherokee Nation Reservation, mean (SD) participant age was 15.59 (0.62) years, and 252 participants (49.0%) self-identified as female. Pain interference was associated with alcohol use and prescription opioid misuse in American Indian/Alaska Native adolescents, controlling for age, gender, food insecurity, anxiety symptoms, and depressive symptoms. Tribal identity significantly moderated the association between pain interference and alcohol use (coefficient, -0.13; 95% CI, -0.23 to -0.02). When Tribal identity was high, the adverse association of pain interference with alcohol use was significantly attenuated. This demonstrates a protective role of Tribal identity on alcohol use, which can inform future substance use prevention efforts among American Indian/Alaska Native adolescents. ClinicalTrials.gov Identifier: NCT04839978.

Biomechanical and histological variables differ by site but not by lameness in equine digital cushion samples from forelimbs

The equine digital cushion (DC) has been a poorly understood structure regarding its mechanical properties and composition. The objective of this study was to develop a sampling technique and to compare the biomechanical and histologic properties of DC between lame and non-lame forelimbs. Both forefeet from horses with induced carpal lameness were radiographed prior to humane euthanasia. Radiographs were used to guide sample collection of two, post-mortem, midline DC samples, palmar and dorsal, via an 8mm biopsy punch. Samples were subjected to compressive testing to determine elastic modulus. Histological evaluation was used to quantify collagen, adipose, ground substance, elastic fibers, and blood vessels. Comparisons of variables between palmar and dorsal DC sites and lame and non-lame limbs were made using student's t-tests or Wilcoxon signed rank tests with P < 0.05. There were no differences in histologic or biomechanical properties in DCs of lame and non-lame forelimbs. The dorsal DC sampling site had a significantly higher median elastic modulus (median: 0.054 MPa, range: 0.001 – 2.110 MPa) and a larger median percentage of ground substance (median: 15 %, 95 % CI: 3 – 30 %) compared to the palmar DC site (elastic modulus: median: 0.023 MPa, range: 0 – 0.576 MPa; ground substance: median 5 %, 95 % CI: 3 – 25 %) (P = 0.03, <0.001; respectively). This study demonstrated that adequate samples could be collected from the DC for biomechanical and histological analysis. Differences in elastic modulus and ground substance between palmar and dorsal samples may reflect different roles of these sites within the DC.

Correlation between the Long Head of the Biceps Microscopic Degeneration and Extent of Apoptotic Process.

Objectives: The purpose of this study was to determine the correlation between microscopic degeneration in the long head of the biceps tendon (LHBT) and the apoptotic process. Methods: This study included 26 consecutive patients who had undergone arthroscopic biceps tenodesis or tenotomy for symptomatic LHBT with or without concomitant rotator cuff tears (RCTs). Histological examination of the specimens under a light microscope was conducted after staining with hematoxylin, eosin, and the Alcian blue. Histopathological changes were assessed using the original Bonar score and the modified Bonar score and then correlated with the expression of the subsequent apoptosis markers: activated caspase-3 (casp3), tumor protein p53 (p53), and B-cell lymphoma 2 (BCL-2). Results: The mean original Bonar score was 8.65 (range 5-11), while the modified Bonar score was 7.61. There was no correlation between the original Bonar score and the age of the patients, but a positive correlation was found between the modified Bonar score and the age of the patients (p = 0.0022). There was no correlation between the age of patients and the expression indexes of BCL-2 and casp3. However, the expression of the p53 index showed a positive correlation with patient aging (p = 0.0441). Furthermore, there was no correlation observed between the expression of apoptotic indexes and both the original and modified Bonar scale. Conclusions: In LHB tendinopathy, the expression of apoptosis does not seem to directly correlate with the extent of degeneration, particularly in the late stages of tendinopathy. However, the transformations observed in collagen and ground substance were significantly associated with age, as well as tendinous tissue degeneration quantified according to modified Bonar score. The age of patients was also linked with the expression of the p53 index, as an increased apoptosis in the studied population.

Sensitivity analysis of fibrous thick-walled tubes with mechano-sensitive remodeling fibers in homeostasis

In this article, we apply the sensitivity analysis method to capture the influence of various parameters on the inflation pressure, axial force, and the deformation for an inflated and axially stretched cylinder. The material consists of an isotropic ground substance material reinforced with fibers that undergo a continuous and mechano-sensitive remodeling process. The input parameters of the mechanical system are assumed to be distributed according to the uniform probability distribution function. In the sensitivity analysis, we apply the Sobol method to determine how the variations of input parameters affect the inflation as well as the axial force in the cylinder. Special attention is given to the fiber remodeling process associated with a homeostatic balance between the constant fiber creation process and the strain-stabilized fiber dissolution. The results may help to understand the importance of the effect of material parameter changes, for example, due to remodeling processes in the context of diseases or recovering processes, on the overall tissue behavior.

Mechanisms, Efficacy, and Clinical Applications of Platelet-Rich Plasma in Tendinopathy: A Comprehensive Review.

Tendinopathy poses a significant clinical challenge characterized by chronic tendon pain, swelling, and impaired function, affecting athletes and the general population. Current treatments often provide limited success, necessitating exploration into regenerative therapies such as platelet-rich plasma (PRP). PRP harnesses the regenerative potential of autologous platelets and growth factors to promote tendon healing. This review aims to comprehensively examine the mechanisms, efficacy, and clinical applications of PRPin tendinopathy. We discuss the pathophysiology of tendinopathy, highlighting collagen disorganization, increased ground substance, and inflammatory changes. PRP's action mechanism involves releasing bioactive molecules that stimulate cellular proliferation, collagen synthesis, and tissue remodeling. Clinical studies and trials evaluating PRP in various tendinopathies, including Achilles, patellar, and rotator cuff tendinopathy, are reviewed to assess its efficacy and effectiveness compared to traditional therapies. Practical aspects, such as preparation methods, injection techniques, and safety considerations, are discussed to provide insights into optimal PRP administration. Challenges, including protocol variability and evidence gaps, are addressed, and future research and clinical practice directions are proposed. By synthesizing current knowledge, this review aims to guide clinicians in enhancing treatment strategies and advancing the field of tendon regenerative medicine.

Long-Term Follow-Up of Pediatric Excimer Laser-Assisted Penetrating Keratoplasty for Congenital Stromal Corneal Dystrophy.

The purpose of this study was to highlight characteristic clinical and microscopic findings and report the long-term follow-up of pediatric excimer laser-assisted penetrating keratoplasty (excimer-PKP) for congenital stromal corneal dystrophy (CSCD). A 2-year-old Greek child presented with CSCD at our department. Clinical examination showed bilateral flake-like whitish corneal opacities affecting the entire corneal stroma up to the limbus. Genetic testing identified a mutation of the decorin gene (c.962delA). The variant was not present in the parents and represented a de novo mutation. The uncorrected visual acuity was 20/100 in both eyes. Excimer-PKP (8.0/8.1 mm) was performed on the right eye at the age of 2.5 years and on the left eye at the age of 3 years. Postoperatively, alternating occlusion treatment was performed. The light microscopic examination demonstrated a disorganized extracellular matrix of the corneal stroma characterized by a prominent irregular arrangement of stromal collagen lamellae with large interlamellar clefts containing ground substance, highlighted by periodic acid-Schiff- and Alcian blue-positive reaction detecting acid mucopolysaccharides. Electron microscopy showed disorganization and caliber variation of collagen lamellae and thin filaments within an electron-lucent ground substance. The postoperative course was unremarkable. Both grafts remained completely clear 14 years postoperatively. Corneal tomography showed moderate regular astigmatism with normal corneal thickness. The corrected distance visual acuity was 20/25 in both eyes. Excimer-PKP for CSCD might be associated with excellent long-term results and a good prognosis, particularly when the primary surgery is performed at a very young age. However, this requires close postoperative follow-up examinations by an experienced pediatric ophthalmologist to avoid severe amblyopia.

The effect of L-Arginine therapy on achilles tendon healing: A histological and biomechanical investigation in an animal model

PurposeSeveral clinical and experimental studies have revealed that L-Arginine, which has antioxidant properties, accelerates tissue healing. This study examined the in vivo effects of oral L - Arginine supplementation on tendon regeneration in Wistar rats. MethodFor each weighting of an average of 250–300 g, 24 Wistar rats were separated into three equal groups. Each rat's right hind leg Achilles tendons were tenotomized and then repaired. The first group (Control) was followed up with a regimen of standard food and water. In the second group (L-Arg Low Dose), 300 mg/kg, and in the third group (L-Arg High Dose), 600 mg/kg L-Arginine was administered in water daily with a regimen of standard food and water ad libitum. After eight weeks, the rats were sacrificed, and the tendons were histologically and biomechanically analyzed. ResultsTendon peak strength values of the L-Arg Low Dose and L-Arg High Dose groups were similar but significantly higher than the control group. A statistically significant difference was observed between the groups in terms of ground substance, fiber arrangement, cellularity, hyalinization, and GAG properties ( p = 0.05, p = 0.002, p = 0.016, p = 0.027, p = 0.05). There was no statistically significant difference between the groups according to the histological examination of collagen properties, fiber structure, tenocyte properties, rounding of the nuclei, and collagen stainability. (p = 0.999, p = 0.061, p = 0.195, p = 0.195, p = 0.130). No mortality, wound complications, or re-ruptures were observed. ConclusionCompared with the control group, histologically and biomechanically distinct therapeutic effects of L-Arginine supplementation on tendon healing were determined. Level of clinical evidence5

A Myxofibroma of the Soft Tissue of Face: A Rare Case Report

Myxoma is a locally invasive neoplasm usually involving the jaw bones, typically occurs between the second and fourth decades. This tumor may comprise 3%-6% of odontogenic tumors. Myxomas of the soft tissue of the face are very rare. We present an unusual case of myxofibroma occurring in a 13-year-old man involving the soft tissue of the face. It congenitally occurred and was a 1 cm sized, ovoid in shape, swelling located on the glabella without any symptoms. An excisional biopsy was performed. A well encapsulated ovoid mass was attached to the corrugator supercilli muscle below the frontalis muscle. It was measured 1.1 x 1 x 0.8 cm and completely excised. Histological examination revealed myxofibroma showing stellate and spinde-shaped cells throughout myxoid ground substance. The unusual features of this case are the site of the tumor, which was localized to the non-tooth bearing area of the mandible and its congenital occurrence history.

Correction of age-related changes in the skin at the dermal and subdermal level using radiofrequency macroneedling therapy.

The negative effects of skin aging are primarily related to the destruction of dermal architectural structure. More specifically, this includes changes in the spatial arrangement of collagen, elastin fibers, mucopolysaccharides, proteoglycans, and ground substances. The purpose of this study is to investigate the histologic effects of dermal and subdermal tissue after a controlled single treatment with radiofrequency (RF) macroneedling. This therapy provides a controlled, localized, thermal effect on the dermis whereby triggering the body's own healing processes of extracellular matrix remodeling. Clinically benefits include skin tightening. Biopsies were obtained for histologic evaluation from four patients (n = 4), 4 weeks after completing a single RF macroneedling facial treatment. Age-related changes of the dermal and subdermal architecture were observed at baseline. After treatment, all biopsies demonstrated an increase in epidermal cells, collagen, elastin, fibroblasts, vasculature, and a decrease in inflammatory cells. The results of this histologic study confirm a significant "subsurfacing" thermal effect from the noncoagulative ascendant thermal injury. The obtained results characterize RF macroneedling therapy as an effective method for correcting age-related changes in facial skin.

Recommendations for Modernizing a Culturally Grounded Substance Use Prevention Program for American Indian and Alaska Native Youth.

American Indian and Alaska Native (AI/AN) youth use alcohol and drugs at a higher rate with earlier onset than the overall youth population in the United States. Youth interventions are needed to support the prevention and reduction of substance misuse-related issues. Connecting AI/AN children to their heritage through culturally grounded prevention programs has been shown to be more effective than programs designed for the general population. The objective of this formative evaluation was to provide community-informed updates for an existing culturally grounded substance use prevention program, The Beauty Way. This study was conducted in partnership with an AI/AN-serving community organization using key informant interviews and talking circles with community members and parents. Participants revealed the challenges and obstacles AI/AN youth face, the impact of cultural values, and activities which engage youth to prevent problematic substance use. Recommendations include the importance of 1) incorporating current challenges to behavioral health such as social media and vaping, 2) including cultural values and activities including land-based learning, and 3) creating a robust facilitator guide and hiring culturally sensitive program staff. These results generated recommendations to strengthen the cultural focus and application of The Beauty Way for AI/AN youth.

Age-dependent changes in collagen crosslinks reduce the mechanical toughness of human meniscus.

The mechanical resilience of the knee meniscus is provided by a group of structural proteins in the extracellular matrix. Aging can alter the quantity and molecular structure of these proteins making the meniscus more susceptible to debilitating tears. In this study, we determined the effect of aging on the quantity of structural proteins and collagen crosslinks in human lateral meniscus, and examined whether the quantity of these molecules was predictive of tensile toughness (area under the stress-strain curve). Two age groups were tested: a young group under 40 and an older group over 65 years old. Using mass spectrometry, we quantified the abundance of proteins and collagen crosslinks in meniscal tissue that was adjacent tothe dumbbell-shaped specimens used to measure uniaxial tensile toughness parallel or perpendicular to the circumferential fiber orientation. We found that the enzymatic collagen crosslink deoxypyridinoline had a significant positive correlation with toughness, and reductions in the quantity of this crosslink with aging were associated with a loss of toughness in the ground substance and fibers. The non-enzymatic collagen crosslink carboxymethyl-lysine increased in quantity with aging, and these increases corresponded to reductions in ground substance toughness. For the collagenous (Types I, II, IV, VI, VIII) and non-collagenous structural proteins (elastin, decorin, biglycan, prolargin) analyzed in this study, only the quantity of collagen VIII was predictive of toughness. This study provides valuable insights on the structure-function relationships of the human meniscus, and how aging causes structural adaptations that weaken the tissue's mechanical integrity.

Impact of cryopreservation on elastomuscular artery mechanics

Low temperatures slow or halt undesired biological and chemical processes, protecting cells, tissues, and organs during storage. Cryopreservation techniques, including controlled media exchange and regulated freezing conditions, aim to mitigate the physical consequences of freezing. Dimethyl sulfoxide (DMSO), for example, is a penetrating cryoprotecting agent (CPA) that minimizes ice crystal growth by replacing intracellular water, while polyvinyl alcohol (PVA) is a nonpenetrating CPA that prevents recrystallization during thawing. Since proteins and ground substance dominate the passive properties of soft biological tissues, we studied how different freezing rates, storage temperatures, storage durations, and the presence of cryoprotecting agents (5% [v/v] DMSO + 1 mg/mL PVA) impact the histomechanical properties of the internal thoracic artery (ITA), a clinically relevant blood vessel with both elastic and muscular characteristics. Remarkably, biaxial mechanical analyses failed to reveal significant differences among the ten groups tested, suggesting that mechanical properties are virtually independent of the cryopreservation technique. Scanning electron microscopy revealed minor CPA-independent delamination in rapidly frozen samples, while cryoprotected ITAs had better post-thaw viability than their unprotected counterparts using methyl thiazole-tetrazolium (MTT) metabolic assays, especially when frozen at a controlled rate. These results can be used to inform ongoing and future studies in vascular engineering, physiology, and mechanics.

The tongue of the red-eared slider (Trachemys scripta elegans): morphological characterization through gross, light, scanning electron, and immunofluorescence microscopic examination

The red-eared slider (Trachemys scripta elegans) is renowned for its remarkable adaptations, yet much of its complex biology remains unknown. In this pioneering study, we utilized a combination of gross anatomy, scanning electron microscopy (SEM), light microscopy, and immunofluorescence techniques to examine the tongue’s omnivorous adaptation in this species. This research bridges a critical knowledge gap, enhancing our understanding of this intriguing reptile. Gross examination revealed a unique arrowhead-shaped tongue with a median lingual fissure and puzzle-piece-shaped tongue papillae. SEM unveiled rectangular filiform, conical, and fungiform papillae, with taste pores predominantly on the dorsal surface and mucous cells on the lateral surface of the papillae. Histologically, the tongue’s apex featured short rectangular filiform and fungiform papillae, while the body exhibited varying filiform shapes and multiple taste buds on fungiform papillae. The tongue’s root contained lymphatic tissue with numerous lymphocytes surrounding the central crypt, alongside lingual skeletal musculature, blood and lymph vessels, and Raffin corpuscles in the submucosa. The lingual striated muscle bundles had different orientations, and the lingual hyaline cartilage displayed a bluish coloration of the ground substance, along with a characteristic isogenous group of chondrocytes. Our research represents the first comprehensive application of immunofluorescence techniques to investigate the cellular intricacies of the red-eared slider’s tongue by employing seven distinct antibodies, revealing a wide array of compelling and significant findings. Vimentin revealed the presence of taste bud cells, while synaptophysin provided insights into taste bud and nerve bundle characteristics. CD34 and PDGFRα illuminated lingual stromal cells, and SOX9 and PDGFRα shed light on chondrocytes within the tongue’s cartilage. CD20 mapped B-cell lymphocyte distribution in the lingual tonsil, while alpha smooth actin (α-SMA) exposed the intricate myofibroblast and smooth muscle network surrounding the lingual blood vessels and salivary glands. In conclusion, our comprehensive study advances our knowledge of the red-eared slider’s tongue anatomy and physiology, addressing a significant research gap. These findings not only contribute to the field of turtle biology but also deepen our appreciation for the species’ remarkable adaptations in their specific ecological niches.

Tranexamic Acid Can Reduce Early Tendon Adhesions After Rotator Cuff Repair and Is Not Detrimental to Tendon-Bone Healing: A Comparative Animal Model Study

PurposeTo determine the effects of topical tranexamic acid (TXA) administration on tendon adhesions, shoulder range of motion (ROM), and tendon healing in an acute rotator cuff (RC) repair rat model. MethodsA total of 20 Sprague–Dawley rats were used. Tendon adhesion, ROM, and biomechanical and histological analysis of tendon-bone healing were conducted at three and six weeks after surgery. The rats underwent rotator cuff repair surgery on both shoulders and were administered TXA via subacromial injections. The tendon adhesion was evaluated macroscopically and histologically. Biomechanical tendon healing was measured using a universal testing machine, and histological analysis was quantified by Hematoxylin & Eosin, Masson’s trichrome, and picrosirius red staining. ResultsAt three weeks after surgery, the adhesion score was significantly lower in the TXA group (2.10 ± 0.32) than in the control group (2.70 ± 0.48, P = .005), but there was no significant difference between the two groups at six weeks. Regarding the ROM, the TXA group showed a significantly higher external rotation (TXA; 36.35° ± 4.52°, Control; 28.42° ± 4.66°, p= .000) and internal rotation (TXA; 45.35° ± 9.36°, Control; 38.94° ± 5.23°, P = .013) than the control group three weeks after surgery. However, at six weeks, there were no significant differences in external and internal rotation between the two groups. In the biomechanical analysis, no significant differences in gross examination (3 weeks; P = .175, 6 weeks: P = .295), load-to-failure (3 weeks; P = .117, 6 weeks; P = .295), and ultimate stress (3 weeks; P = .602, 6 weeks; P = .917) were noted between the two groups three and six weeks after surgery. In the histological analysis of tendon healing, no significant differences in the total score (3 weeks; P = .323, 6 weeks; P = .572) were found between the two groups three and six weeks after surgery. ConclusionThe topical TXA administration showed a beneficial effect in reducing tendon adhesions and improving ROM at three weeks postoperatively and had no effect at six weeks. This suggests that additional intervention with TXA may be useful to achieve long-term improvement in shoulder stiffness. Additionally, TXA may increase tissue ground substance accumulation in the late postoperative period but does not adversely affect tendon-bone interface healing. Clinical RelevanceThe use of TXA after RC repair has no effect on tendon-bone interface healing in clinical practice and can improve shoulder stiffness in the early postoperative period. Additional research is needed on the long-term effects.

Instabilities of an inflated and extended doubly fiber-reinforced cylindrical membrane under damage processes and different natural configurations of its constituents with application to abnormal artery dilation

This article studies extended and inflated tubes made of doubly fiber-reinforced hyperelastic material in which the constituents undergo damage processes at large deformations. Damage processes are initiated by a combination of external loads and material characteristics including volume changes in the ground substance matrix and constituents with different natural configurations. The inflation of such a cylinder is stable at relatively small deformations. Under higher inflation pressures the cylinder is likely to develop various types of instabilities that are shown to be related to loading, geometry, and (current) mechanical properties of the solid. Analyses focus on the role of material volume changes, fiber pre-stretch, and damage processes in the initiation of bulging and inflation-jump instabilities.

On the inflation, bulging/necking bifurcation and post-bifurcation of a cylindrical membrane under limited extensibility of its constituents

We consider the bifurcation and post-bifurcation of an extended and inflated circular cylindrical membrane under limited extensibility of its constituents. First, for illustration of the limited extensibility effect, a membrane made of the (isotropic) Gent model is briefly analyzed. Second, the membrane is considered to be made of an isotropic ground substance reinforced with fibers symmetrically arranged in two helically distributed families which are mechanically equivalent. The mechanical behavior of the fibers in a similar way to the (isotropic) Gent model is taken to reflect fiber limited extensibility. In particular, the materials under consideration are NH models augmented with two functions called reinforcing models, each one accounting for unidirectional reinforcement. For a specific material, since both families are mechanically equivalent, the reinforcing models are equal. The nature of the anisotropy considered, i.e., the reinforcing model, can depend only on the stretch in the fiber direction or can depend on the fiber stretch and also can have an influence on the shear response of the material (i.e., it also captures shearing in the fiber direction). The limitation associated with the material anisotropic deformability as well as the arrangement of the material constituents is discussed with respect to the initiation of bulging and necking for the membrane. The subsequent consequences for configurations in equilibrium during post-bifurcation are also studied in detail and a variety of results are given in terms of the limited extensibility (deformability) of the fibers as well as their mechanical response and arrangement (fiber winding angle).

Recruitment and retention of American Indian youth and caregivers in a culturally adapted prevention program.

This article seeks to understand to what extent cultural engagement and substance use risk factors influence families' decisions to participate, and ultimately complete, a culturally grounded substance use prevention program. Using data from a 14-week culturally oriented family-based substance use prevention program, we examine predictors of successful recruitment and retention of American Indian youth and their caregivers. Guided by the theoretical model for developing culturally specific preventions, the community-based approach to recruitment resulted in 85.6% of eligible families from two American Indian communities agreeing to participate in the randomized controlled trial. After completion of baseline surveys, 57.3% of the intervention selected families initiated participation in the program sessions and 67.8% of these families completed participation in the program. We used logistic regression to analyze two different models: one that predicted whether invited families chose to participate and whether participating families attended eight or more sessions. Important predictors of participation in the intervention program included single-caregiver households, youth Indigenous language and cultural identity, youth early substance use initiation, and household substance use exposure. Overall, results from this study highlight the importance of fully engaged community research partnerships for multi-session family-based interventions, while identifying potential challenges to program recruitment and participation.

Histopathological and histomorphometric investigation of the effects of different irrigation solutions on Achilles tendon healing in rats.

This study aimed to examine the effect of irrigation fluids containing povidone-iodine (PVP-I), rifampicin (RF), and chlorhexidine gluconate (CHG) used during surgery on healing on a rat Achilles tendon model. Twenty-eight male Sprague-Dawley rats (range, 300 to 400 g) were used in the experiment carried out between November 2022 and December 2022. The rats were divided into PVP-I, RF, CHG, and control groups, with seven rats in each group. Following the tenotomy and repair of the right Achilles tendon, the surgical site was irrigated using PVP-I, RF, CHG, or normal saline (the control group) for 2 min. All rats were sacrificed on the 21st postoperative day. The samples were evaluated histomorphometrically using the scoring system modified by Svensson, Soslowsky, and Cook and histopathologically using the Bonar and Movin classifications. The RF group gave better results in all three scoring systems compared to the control, PVP-I, and CHG groups (p=0.008, p=0.002, and p=0.006, respectively). Cellularity, rounding, and tenocyte morphology showed a significant difference in favor of the RF group (p=0.004). While the distribution of ground substance glycosaminoglycans showed a significant difference in favor of the RF group, there was no significant difference among the other groups (p=0.22). Irrigation solutions containing PVP-I, RF, or CHG show no negative effect on Achilles tendon healing. Moreover, the findings suggest that RF irrigation can accelerate the healing process.

IDG-SW3 Cell Culture in a Three-Dimensional Extracellular Matrix.

Osteocytes are considered to be nonproliferative cells that are terminally differentiated from osteoblasts. Osteoblasts embedded in the bone extracellular matrix (osteoid) express the Pdpn gene to form cellular dendrites and transform into preosteocytes. Later, preosteocytes express the Dmp1 gene to promote matrix mineralization and thereby transform into mature osteocytes.This process is called osteocytogenesis. IDG-SW3 is a well-known cell line for in vitro studies of osteocytogenesis. Many previous methods have used collagen I as the main or the only component of the culturing matrix. However, in addition to collagen I, the osteoid also contains a ground substance, which is an important component in promoting cellular growth, adhesion, and migration. In addition, the matrix substance is transparent, which increases the transparency of the collagen I-formed gel and, thus, aids the exploration of dendrite formation through imaging techniques. Thus, this paper details a protocol to establish a 3D gel using an extracellular matrix along with collagen I for IDG-SW3 survival. In this work, dendrite formation and gene expression were analyzed during osteocytogenesis. After 7 days of osteogenic culture, an extensive dendrite network was clearly observed under a fluorescence confocal microscope. Real-time PCR showed that the mRNA levels of Pdpn and Dmp1 continually increased for 3 weeks. At week 4, the stereomicroscope revealed an opaque gel filled with mineral particles, consistent with the X-ray fluorescence (XRF) assay. These results indicate that this culture matrix successfully facilitates the transition from osteoblasts to mature osteocytes.

Cardiac extracellular matrix at microvascular obstruction area after reperfused myocardial infarction: a morphometric study

Abstract Background Extracellular matrix (ECM), a structural and biomechanical support to cardiomyocytes, suffers substantial alterations after myocardial infarction (MI). Despite a complete reopening at epicardial level, hypoperfusion within the infarcted myocardium, known as microvascular obstruction (MVO), occurs. Extensive clinical studies and meta-analysis reported the association between the magnitude of MVO and the appearance of adverse remodeling; thus, scrutinizing ECM composition within the infarcted areas with impaired tissue-level reperfusion could provide fundamental insight regarding MVO pathophysiology. Purpose To histologically compare ECM composition within the infarct zone regarding the presence or absence of MVO using an experimental swine model of reperfused MI. Methods MI was induced in swine (n=10) by transitory 90-min coronary occlusion followed by 7 days of reperfusion. Prior to euthanasia, intracoronary thioflavin-S was infused. Within the infarcted myocardium, regions displaying MVO (thioflavin-S-) or no MVO (thioflavin-S+) were isolated and stained to morphometrically compare ECM composition. Results Regarding cellularity, areas with MVO displayed an enlarged presence of neutrophils and lymphocytes, whilst no differences in the amount of macrophages and myofibroblasts were detected in comparison to no MVO-myocardium. Those regions with macroscopic MVO showed lower capillary density than those without MVO. According to the fibers and ground substance, a significant reduction in the extension of type I collagen, laminin, and fibronectin together with an augmentation of glycosaminoglycan were noted in areas showing MVO compared to those without microvascular injury. No changes in the amount of type III collagen was observed. Conclusion The ECM composition in infarcted regions with MVO displays a higher presence of inflammatory infiltrate and glycosaminoglycans as well as a reduced amount of microvessels and fibers compared to those areas without microvascular hypoperfusion. These characteristics might underlie the development of adverse ventricular remodeling in MI patients with extensive MVO.