A comparison of native vaginal and ligament surgery for cure of pelvic organ prolapse and overactive bladder.

The key messages from the Shkarupa et al. native cardinal/uterosacral ligament (CL/USL) study, was that, in premenopausal women, ligament repair alone is sufficient for cure of pelvic organ prolapse (POP) and urgency, achieving cure rates of 85.7% for POP and 81.6% for urgency at 12 months. However, in postmenopausal women, the cure rates were 20.5% for POP and 33.3% for urge at 12 months. The Lancet Prospect Trial recorded 21% for native vaginal repair at 12 months. The poor POP cure rate in the Prospect Trial, and the rapid deterioration in the post-menopausal CL/USL repair group, can be explained by known biomechanics. The vagina has little structural strength. Ligaments, with a much higher breaking strain, are the main structural support of pelvic organs. Yet, even native ligament repair reported very low cure rates at 12 months. The poor results in postmenopausal women with native ligament repair can be explained by collagen breakdown after the menopause, as collagen is the key structural component of ligaments. An important question posed in the ligament repair study was, "What happens to women cured by ligament repair after the menopause when the collagen leaches out of the ligaments?". One recommendation was that collagen creating tapes be routinely applied in prolapse surgery and OAB, at least in postmenopausal women. The recommendation for routine collagen-creating ligament repair methods, especially in older women, are supported by high 5-year surgical cure rates in 70-year-old Japanese women, 91.2% for POP, at 12 months, falling to 79.0 at 60 months, using collagen creating Tissue Fixation System (TFS) minislings.

Further developments of pubourethral ligament surgery for stress urinary incontinence.

Midurethral slings (MUS) have revolutionized the treatment of stress urinary incontinence (SUI). MUS operations work by creating a collagenous pubourethral ligament (PUL). Since 1996, more than 10 million operations have been performed worldwide. Early complications with the MUS included bowel perforations, massive retropubic hemorrhages, nerve injuries, even death. Though the invention of the transobturator tape (TOT) operation, and later, minislings, has eliminated many such complications, the most frequent complication, post-operative urinary retention, remains. MUS operations are unavailable in many countries because of expense. Low-cost surgical options discussed include the tension-free artisan minisling which uses a 10 cm × 1 cm tape inserted as a "U" below the urethra; 91% cure was achieved at 5.7 years in a study of 90 women, though it was accompanied by a 4.2% erosion rate. The more recent urethral ligament plication (ULP) is based on transperineal ultrasound studies which showed that the main cause of the SUI was elongation of weak PULs. This allowed the posterior pelvic muscles to open out the posterior urethral wall to cause SUI. Basic science collagen studies indicated that suturing PULs with No. 2 wide-bore polyester sutures would provide sufficient collagen to repair weakened PULs. Cure of SUI, when it occurred, was immediate. Reference to the original experimental animal studies indicated that collagen 1, the key structural support of PUL, had formed by 3 months. This is an optimistic sign for longer term cure, substantiated by very little deterioration after 3 months over a 12-month period in the first surgical trial (unpublished data). In conclusion, the ULP operation can be performed under local anesthesia/sedation. If it fulfils its promise for longer-term cure, SUI cure will be available for hundreds of millions of women in underdeveloped countries for a few dollars per case.

Structural, functional, and dysfunctional pelvic anatomy.

The structural basis of the Integral Theory is holistic. Four main pelvic muscles interact holistically with five main pelvic ligaments to maintain pelvic organ structure and function. The vagina is structurally weak. The support it provides to the bladder base is contingent on being stretched by opposite pelvic muscle forces, much like a trampoline. Its main role is to transmit muscle forces to facilitate continence, evacuation and control of urgency. Therefore, as an organ that cannot regenerate, the vagina should be conserved, and not excised. The ligaments provide the main structural support for the organs and are the most vulnerable part of the anatomical system to injury because their structural collagen is depolymerized prior to labour, and stretched during labour. Further ligament weakening occurs after menopause due to collagen breakdown. Hence, collagen loss is the main cause of organ prolapse and lower urinary tract symptoms (LUTS). The strengthening of damaged ligaments, whether surgically or non-surgically, can improve or cure symptoms and prolapse. Because collagen loss in ligaments is a principal cause of dysfunction in older women, collagen-creating techniques are advised: precisely inserted tapes to create neoligaments, or wide-bore No. 2 or No. 3 polyester ligament sutures instead of dissolvable sutures.

Wide-bore polyester sutures may create sufficient collagen for cure of prolapse/incontinence: a work in progress.

The main thrust of the Integral Theory Paradigm (ITP) is that inadequate ligament collagen causes pelvic organ prolapses (POP) and pelvic symptoms, a concept validated by multiple publications which cured POP and bladder/bowel/pain dysfunctions by collagen-creating slings. Sling surgery for surgical cure of these conditions was eliminated in the United States, Europe and other regulatory jurisdictions by banning all mesh products (including tapes) in about 2017. The aim of this work was to inform of the progress of a highly promising alternative method for collage creation for ligament repair: wide-bore polyester sutures accurately applied to weak ligaments. The scientific rationale for the wide-bore polyester plication method was a revisit and analysis of prior Instron testing data from a rejected polyester aortic graft from a doctoral thesis. The analysis indicated that the collagen produced by No. 2 polyester sutures would be sufficient to repair weakened pelvic ligaments. The surgical methodology consisted of application of wide-bore No. 2 or No. 3 polyester sutures to existing vaginal surgical techniques such as cardinal/uterosacral ligament (CL/USL) repair in the Fothergill operation, deep transversus perinei (DTP) ligamentous supports of the perineal body (PB) and uniquely, pubourethral ligament (PUL) repair for stress urinary incontinence (SUI). No vaginal tissue was excised. These operations are now being performed in several centres around the world. Because of this, the results detailed below are indicative only, and necessarily incomplete, as they are only from these units. Twelve month data (n=35) for SUI cure (83%) following PUL repair by the urethral ligament plication (ULP) operation has been submitted for publication; POP quantification (POPQ) points Ba, C, Bp, D were significantly improved at 6 weeks postoperative review following repair of CLs (cystocele) and USLs (uterine/apical prolapse) (n=56): deep transverse perinei ligament repair (descending perineal syndrome "DPS") (n=4) were cured at 6-12 months review. Though numbers are few, in the context of DPS being considered incurable, these numbers are significant. Except for the ULP operation, the techniques for cystocele, uterine prolapse, perineocele were essentially evolved versions of the Fothergill and standard PB repairs without any vaginal or ligament excisions. Though promising, more extensive and longer-term results are clearly required before this wide-bore polyester ligament repair method can become mainstream.

Tension-free artisan tape: a low-cost option for cure of pelvic organ prolapse and stress incontinence.

The Lancet PROSPECT Trial has shown that vaginal repair has dismal cure rates of some 20% at 12 months. Meanwhile 10-year data from collagen creating ligament repair methods (implanted mini-sling tapes), with no vaginal excision, report very high, long-term cure rates. The reason for conserving the vagina, is that the vagina's main function is to transmit the muscle forces for external urethral closure or opening. Ligaments provide the main structural support for the organs, much like a suspension bridge. Collagen is the key structural component of the ligaments which structurally support the organs. However, collagen breaks down after the menopause and is excreted as hydroxyproline. If sufficient collagen breaks down, the ligaments weaken, and this explains the 80% failure rates for native ligament in the Lancet PROSPECT Trial. Whereas satisfactory results for pelvic organ prolapse (POP) and symptoms have been obtained with native ligament repair in premenopausal women, it has been shown that collagen-creating ligament repair method, for example, precisely inserted tapes, is required in older women. Tension-free" artisan tapes work in the same way as commercial tape kits which have been used to cure stress urinary incontinence (SUI) and POP. The "tension-free" artisan tape results for POP at three years were encouraging, but were applied only in a small number of cases. Very recently, long-term (5.7 years) tension-free artisan tape data has become available from artisan SUI surgery. Results from 93 women using an artisan transobturator tape (TOT) achieved a cure rate of 91.3% at a mean of 5.7 years postoperatively. The only significant complication was a 4.3% erosion rate. The implications are that tension-free artisan tape for POP is also likely to be long-lasting. Another implication is the cost, which, for each tape, is a few Euros. The low cost allows the artisan method to be applied even in the poorest nations.

Principles of surgery according to the Integral Theory Paradigm (ITP).

A core concept of the Integral Theory System is that "ligaments are for structure; vagina is for function". The vagina and uterus should be conserved. Because the vagina is an organ, its collagen and elastin, which are so necessary for its function, cannot regenerate once they are removed. Removing the uterus involves severing the descending uterine artery, which is the principal blood supply of the proximal part of the uterosacral ligaments (USLs), and so may cause atrophy, which can cause future incontinence problems because of collagen loss after menopause. The diagnostic algorithm guides which of the five pelvic ligaments need repair. Native ligament plication can be adequate for prolapse/symptom cure, but only in premenopausal women. Postmenopausal women are usually collagen deficient and require collagen-creating tapes or wide-bore polyester sutures to restore structural collagen in the ligaments. Of extreme importance, vaginal tissue excision should be avoided, as consequent scarring may cause "tethered vagina syndrome" (TVS). TVS can cause massive uncontrolled urine loss because the scar tissue in the bladder neck area of the vagina can link the more powerful posterior muscles to the anterior, so the posterior urethra wall is forcibly pulled open, when given the signal to close. Instead of vaginal excision, a "concertina" suture technique re-assigns and shrinks excess vaginal tissue to normal anatomy by 6 weeks. In conclusion, the five key surgical principles of the Integral Theory System are: ligaments are for structure, vagina is for function; structure (prolapse) and function (symptoms) are related; repair the structure and you will restore the function; avoid vaginal excision and hysterectomy; create new collagen to reinforce the damaged ligaments.

Biomechanical functions analysis of the Mallard webbed foot: A study of macroscopic and microscopic material assembly and tendon morphology.

The mallard webbed foot represents an exemplary model of biomechanical efficiency in avian locomotion. This study delves into the intricate material assembly and tendon morphology of the mallard webbed foot, employing both macroscopic and microscopic analyses. Through histological slices and scanning electron microscopy (SEM), we scrutinized the coupling assembly of rigid and flexible materials such as skin, tendon, and bone, while elucidating the biomechanical functions of tendons across various segments of the tarsometatarsophalangeal joint (TMTPJ). The histological examination unveiled a complex structural hierarchy extending from the external integument to the skeletal framework. Notably, the bone architecture, characterized by compact bone and honeycombed trabeculae, showcases a harmonious blend of strength and lightweight design. Tendons, traversing the phalangeal periphery, surrounded by elastic fibers, collagen fibers, and fat tissue. Fat chambers beneath the phalanx, filled with adipocytes, provide effective buffering, enabling the phalanx to withstand gravity, provide support, and facilitate locomotion. Furthermore, SEM analysis provided insights into the intricate morphology and arrangement of collagen fiber bundles within tendons. Flexor tendons in proximal and middle TMTPJ segments adopt a wavy-type, facilitating energy storage and release during weight-bearing activities. In contrast, distal TMTPJ flexor tendons assume a linear-type, emphasizing force transmission across phalangeal interfaces. Similarly, extensor tendons demonstrate segment-specific arrangements tailored to their respective biomechanical roles, with wavy-type in proximal and distal segments for energy modulation and linear-type in middle segments for enhanced force transmission and tear resistance. Overall, our findings offer a comprehensive understanding of the mallard webbed foot's biomechanical prowess, underscoring the symbiotic relationship between material composition, tendon morphology, and locomotor functionality. This study not only enriches our knowledge of avian biomechanics but also provides valuable insights for biomimetic design and tissue engineering endeavors.

Sensitivity of magnetic resonance elastography to extracellular matrix and cell motility in human prostate cancer cell line-derived xenograft models.

Prostate cancer (PCa) is a significant health problem in the male population of the Western world. Magnetic resonance elastography (MRE), an emerging medical imaging technique sensitive to mechanical properties of biological tissues, detects PCa based on abnormally high stiffness and viscosity values. Yet, the origin of these changes in tissue properties and how they correlate with histopathological markers and tumor aggressiveness are largely unknown, hindering the use of tumor biomechanical properties for establishing a noninvasive PCa staging system. To infer the contributions of extracellular matrix (ECM) components and cell motility, we investigated fresh tissue specimens from two PCa xenograft mouse models, PC3 and LNCaP, using magnetic resonance elastography (MRE), diffusion-weighted imaging (DWI), quantitative histology, and nuclear shape analysis. Increased tumor stiffness and impaired water diffusion were observed to be associated with collagen and elastin accumulation and decreased cell motility. Overall, LNCaP, while more representative of clinical PCa than PC3, accumulated fewer ECM components, induced less restriction of water diffusion, and exhibited increased cell motility, resulting in overall softer and less viscous properties. Taken together, our results suggest that prostate tumor stiffness increases with ECM accumulation and cell adhesion - characteristics that influence critical biological processes of cancer development. MRE paired with DWI provides a powerful set of imaging markers that can potentially predict prostate tumor development from benign masses to aggressive malignancies in patients. STATEMENT OF SIGNIFICANCE: Xenograft models of human prostate tumor cell lines, allowing correlation of microstructure-sensitive biophysical imaging parameters with quantitative histological methods, can be investigated to identify hallmarks of cancer.

Collagen degradation assessment with an in vitro rotator cuff tendinopathy model using multiparametric ultrashort-TE magnetization transfer (UTE-MT) imaging.

PURPOSE: This study aims to assess ultrashort-TE magnetization transfer (UTE-MT) imaging of collagen degradation using an in vitro model of rotator cuff tendinopathy. METHODS: Thirty-six supraspinatus tendon specimens were divided into three groups and treated with 600 U collagenase (Group 1), 150 U collagenase (Group 2), and phosphate buffer saline (Group 3). UTE-MT imaging was performed to assess changes in macromolecular fraction (MMF), macromolecule transverse relaxation time (T2m), water longitudinal relaxation rate constant (R1m), the magnetization exchange rate from the macromolecular to water pool (Rm0 w) and from water to the macromolecular pool (Rm0 m), and magnetization transfer ratio (MTR) at baseline and following digestion and their differences between groups. Biochemical and histological studies were conducted to determine the extent of collagen degradation. Correlation analyses were performed with MMF, T2m, R1m, Rm0 w, Rm0 m, and MTR, respectively. Univariate and multivariate linear regression analyses were performed to evaluate combinations of UTE-MT parameters to predict collagen degradation. RESULTS: MMF, T2m, R1m, Rm0 m, and MTR decreased after digestion. MMF (r = -0.842, p < 0.001), MTR (r = -0.78, p < 0.001), and Rm0 m (r = -0.662, p < 0.001) were strongly negatively correlated with collagen degradation. The linear regression model of differences in MMF and Rm0 m before and after digestion explained 68.9% of collagen degradation variation in the tendon. The model of postdigestion in MMF and T2m and the model of MTR explained 54.2% and 52.3% of collagen degradation variation, respectively. CONCLUSION: This study highlighted the potential of UTE-MT parameters for evaluation of supraspinatus tendinopathy.

Exposure to atrazine and endosulfan alters oviductal adenogenesis in the broad-snouted caiman (Caiman latirostris).

The molecular pathways involved in oviductal adenogenesis are highly conserved among vertebrates. In this work, we study the histomorphological changes and molecular pathways involved in Caiman latirostris oviductal adenogenesis and the effects of in ovo exposure to environmentally relevant doses of endosulfan (END) and atrazine (ATZ) on these processes. To this end, the histomorphological changes at epithelial and subepithelial compartments, the protein expressions of ß-catenin and Wnt-7a, and the gene expression of metalloproteinases (MMPs) and its inhibitors (TIMPs) were evaluated as biomarkers of oviductal adenogenesis in prepubertal juvenile C. latirostris. Exposure to END altered adenogenesis-related epithelium characteristics and mRNA expression of MMP2, MMP9, and TIMP1. Exposure to ATZ increased the width of the subepithelial stroma with loosely arranged collagen fibers and increased ß-catenin expression in buds (invaginated structures that precede glands). The results demonstrate that in ovo exposure to ATZ and END alters oviductal adenogenesis at tissue, cellular, and molecular levels. An altered oviductal adenogenesis could impair fertility, raising concern on the effects of pesticide pollution in wildlife and domestic animals.

Collagen-Mesenchymal Stem Cell Microspheres Embedded in Hyaluronic Acid Solutions as Biphasic Stem Niche Delivery Systems for Pulmonary Differentiation.

Cell therapy has the potential to become a feasible solution for several diseases, such as those related to the lungs and airways, considering the more beneficial intratracheal administration route. However, in lung diseases, an impaired pulmonary extracellular matrix (ECM) precludes injury resolution with a faulty engraftment of mesenchymal stem cells (MSCs) at the lung level. Furthermore, a shielding strategy to avoid cell damage as well as cell loss due to backflow through the injection path is required. Here, an approach to deliver cells encapsulated in a biomimetic stem niche is used, in which the interplay between cells and physiological lung ECM constituents, such as collagen and hyaluronic acid (HA), can occur. To this aim, a biphasic delivery system based on MSCs encapsulated in collagen microspheres (mCOLLs) without chemical modification and embedded in an injectable HA solution has been developed. Such biphasic delivery systems can both increase the mucoadhesive properties at the site of interest and improve cell viability and pulmonary differentiation. Rheological results showed a similar viscosity at high shear rates compared to the MSC suspension used in intratracheal administration. The size of the mCOLLs can be controlled, resulting in a lower value of 200 µm, suitable for delivery in alveolar sacs. Biological results showed that mCOLLs maintained good cell viability, and when they were suspended in lung medium implemented with low molecular weight HA, the differentiation ability of the MSCs was further enhanced compared to their differentiation ability in only lung medium. Overall, the results showed that this strategy has the potential to improve the delivery and viability of MSCs, along with their differentiation ability, in the pulmonary lineage.

Galunisertib downregulates mutant type I collagen expression and promotes MSCs osteogenesis in pediatric osteogenesis imperfecta.

Qualitative alterations in type I collagen due to pathogenic variants in the COL1A1 or COL1A2 genes, result in moderate and severe Osteogenesis Imperfecta (OI), a rare disease characterized by bone fragility. The TGF-ß signaling pathway is overactive in OI patients and certain OI mouse models, and inhibition of TGF-ß through anti-TGF-ß monoclonal antibody therapy in phase I clinical trials in OI adults is rendering encouraging results. However, the impact of TGF-ß inhibition on osteogenic differentiation of mesenchymal stem cells from OI patients (OI-MSCs) is unknown. The following study demonstrates that pediatric skeletal OI-MSCs have imbalanced osteogenesis favoring the osteogenic commitment. Galunisertib, a small molecule inhibitor (SMI) that targets the TGF-ß receptor I (TßRI), favored the final osteogenic maturation of OI-MSCs. Mechanistically, galunisertib downregulated type I collagen expression in OI-MSCs, with greater impact on mutant type I collagen, and concomitantly, modulated the expression of unfolded protein response (UPR) and autophagy markers. In vivo, galunisertib improved trabecular bone parameters only in female oim/oim mice. These results further suggest that type I collagen is a tunable target within the bone ECM that deserves investigation and that the SMI, galunisertib, is a promising new candidate for the anti-TGF-ß targeting for the treatment of OI.

Targeting the HSP47-collagen axis inhibits brain metastasis by reversing M2 microglial polarization and restoring anti-tumor immunity.

Brain metastases (BrMs) are the leading cause of death in patients with solid cancers. BrMs exhibit a highly immunosuppressive milieu and poor response to immunotherapies; however, the underlying mechanism remains largely unclear. Here, we show that upregulation of HSP47 in tumor cells drives metastatic colonization and outgrowth in the brain by creating an immunosuppressive microenvironment. HSP47-mediated collagen deposition in the metastatic niche promotes microglial polarization to the M2 phenotype via the α2ß1 integrin/nuclear factor κB pathway, which upregulates the anti-inflammatory cytokines and represses CD8+ T cell anti-tumor responses. Depletion of microglia reverses HSP47-induced inactivation of CD8+ T cells and abolishes BrM. Col003, an inhibitor disrupting HSP47-collagen association restores an anti-tumor immunity and enhances the efficacy of anti-PD-L1 immunotherapy in BrM-bearing mice. Our study supports that HSP47 is a critical determinant of M2 microglial polarization and immunosuppression and that blocking the HSP47-collagen axis represents a promising therapeutic strategy against brain metastatic tumors.

Anaesthesia management of a patient with Bethlem Myopathy for elective tonsillectomy: a case report.

BACKGROUND: Bethlem Myopathy is a collagen VI-related myopathy presenting as a rare hereditary muscular disorder with progressive muscular weakness and joint contractures. Despite its milder clinical course relative to other myopathies, anaesthetic management can be challenging. High arched palates and fixed flexion deformities may contribute to a difficult airway. A progressive decline in pulmonary function can present later into adulthood. This respiratory decline can carry secondary cardiovascular consequences due to the progressive nature of restrictive lung disease, including right sided heart disease and pulmonary hypertension. We describe a case of a male patient with Bethlem Myopathy undergoing anaesthesia, to contribute to the limited body of literature on this condition and enhance awareness and guidance amongst anaesthesiologists on approaching patients with this condition. This is the first case report within the literature of its kind. CASE PRESENTATION: This case details a 33-year-old male with Bethlem Myopathy undergoing tonsillectomy. Diagnosed in childhood following developmental delays, the patient had no prior anaesthetic exposure and no family history of anaesthetic complications. Anaesthetic induction was achieved without complications, avoiding depolarizing muscle relaxants and careful airway management. Extreme care was taken in patient positioning to prevent complications. The surgery proceeded without incident and muscle paralysis was reversed with Suggammadex, resulting in no adverse post-operative respiratory complications. The patient was discharged on the first post-operative day without any respiratory or cardiovascular compromise. CONCLUSIONS: Bethlem Myopathy, while often exhibiting a mild clinical course, can present anaesthetic challenges. Awareness of potential complications including a difficult airway, cardiovascular and respiratory implications as well as the need for specialised monitoring and positioning is crucial to ensure a safe peri-operative course.

The Cryoprotective Effect of an Antifreeze Collagen Peptide Complex Obtained by Enzymatic Glycosylation on Tilapia.

Antifreeze peptides have become effective antifreeze agents for frozen products, but their low quantity of active ingredients and high cost limit large-scale application. This study used the glycosylation of fish collagen peptides with glucosamine hydrochloride catalyzed by transglutaminase to obtain a transglutaminase-catalyzed glycosylation product (TGP) and investigate its antifreeze effect on tilapia. Compared with the blank group, the freshness (pH value of 6.31, TVB-N value of 21.7 mg/100 g, whiteness of 46.28), textural properties (especially hardness and elasticity), and rheological properties of the TGP groups were significantly improved. In addition, the protein structures of the samples were investigated using UV absorption and fluorescence spectroscopy. The results showed that the tertiary structure of the TGP groups changed to form a dense polymer. Therefore, this approach can reduce the denaturation and decomposition of muscle fibers and proteins in fish meat more effectively and has a better protective effect on muscle structure and protein aggregation, improving the stability of fish meat. This study reveals an innovative method for generating antifreeze peptides by enzymatic glycosylation, and glycosylated fish collagen peptide products can be used as new and effective green antifreeze agents in frozen foods.

"Molecular mechanisms of mechanosensing and plasticity of tendons and ligaments".

Tendons and ligaments, crucial components of the musculoskeletal system, connect muscles to bones. In the realm of sports, tendons and ligaments are vulnerable tissues with injuries such as Achilles tendon rupture and anterior cruciate ligament tears directly impacting an athlete's career. Furthermore, repetitive trauma and tissue degeneration can lead to conditions like secondary osteoarthritis, ultimately affecting the overall quality of life. Recent research highlights the pivotal role of mechanical stress in maintaining homeostasis within tendons and ligaments. This review delves into the latest insights on the structure of tendons and ligaments and the plasticity of tendon tissue in response to mechanical loads.

Multi-acrylamides improve bond stability through collagen reinforcement under physiological conditions.

OBJECTIVES: Acrylamides were shown to significantly improve bonding stability in adhesive restorations, but the reinforcement mechanism has not been fully elucidated. We tested the hypothesis that hydrogen bonding reinforcement of the collagen network (with secondary or tertiary acrylamides), as well as degree of crosslinking of the polymer network (with di- or tri-functional acrylamides), can be two of the factors at play. METHODS: Two-step total etch adhesives comprising UDMA (60 wt%) and 40 wt% of: TAAEA, TMAAEA (secondary, tertiary tri-acrylamides), BAAP, DEBAAP (secondary, tertiary di-acrylamides) or HEMA (mono-methacrylate - control) were formulated. Simulated composite restorations (n = 5) were tested after cyclic mechanical and biological (S. mutans biofilm) challenges. Gap formation before and after aging was assessed with SEM imaging. Micro-tensile bond strength (µTBS, n = 6) was assessed after seven-day incubation in water or S. mutans-containing culture medium. Collagen reinforcement was assessed with hydroxyproline assay (n = 10) and rheology (n = 3). Data were analyzed with one-way/two-way ANOVA/Tukey's test (alpha=5%). RESULTS: Gap formation increased and bond strength decreased for all monomers after biofilm incubation (p < 0.001). Except for DEBAAP, secondary and tertiary di/tri-acrylamides showed lower occlusal gap width values, but no significant differences overall gap length compared to HEMA. µTBS increased for tri-acrylamides compared with HEMA. Samples treated with multi-acrylamides had lower concentration of hydroxyproline (by-product of collagen degradation) (p < 0.001), except for DEBAAP, which showed values close to HEMA (p > 0.05). Dentin shear modulus increased for all acrylamides after 72 h, especially TMAAEA. SIGNIFICANCE: In general, multi-acrylamides promote collagen reinforcement, leading to reduced gap formation, and stabilize the bond strength under physiological conditions.

OPN, BSP, and Bone Quality-Structural, Biochemical, and Biomechanical Assessment in OPN-/-, BSP-/-, and DKO Mice.

Osteopontin (OPN) and Bone Sialoprotein (BSP), abundantly expressed by osteoblasts and osteoclasts, appear to have important, partly overlapping functions in bone. In gene-knockout (KO, -/-) models of either protein and their double (D)KO in the same CD1/129sv genetic background, we analyzed the morphology, matrix characteristics, and biomechanical properties of femur bone in 2 and 4 month old, male and female mice. OPN-/- mice display inconsistent, perhaps localized hypermineralization, while the BSP-/- are hypomineralized throughout ages and sexes, and the low mineralization of young DKO mice recovers with age. The higher contribution of primary bone remnants in OPN-/- shafts suggests a slow turnover, while their lower percentage in BSP-/- indicates rapid remodeling, despite FTIR-based evidence in this genotype of a high maturity of the mineralized matrix. In 3-point bending assays, OPN-/- bones consistently display higher Maximal Load, Work to Max. Load and in young mice Ultimate Stress, an intrinsic characteristic of the matrix. Young male and old female BSP-/- also display high Work to Max. Load along with low Ultimate Stress. Principal Component Analysis confirms the major role of morphological traits in mechanical competence, and evidences a grouping of the WT phenotype with the OPN-/- and of BSP-/- with DKO, driven by both structural and matrix parameters, suggesting that the presence or absence of BSP has the most profound effects on skeletal properties. Single or double gene KO of OPN and BSP thus have multiple distinct effects on skeletal phenotypes, confirming their importance in bone biology and their interplay in its regulation.