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Journal of the Mechanical Behavior of... Jan 2024To evaluate the effect of firing temperature and heating rate on the volumetric shrinkage, translucency, flexural strength, hardness, and fracture toughness of a...
PURPOSE
To evaluate the effect of firing temperature and heating rate on the volumetric shrinkage, translucency, flexural strength, hardness, and fracture toughness of a zirconia veneering ceramic.
MATERIAL AND METHODS
Zirconia veneering ceramic specimens (N = 45) with varying final temperatures (730 °C, 750 °C, and 770 °C) and heating rates (70 °C/min, 55 °C/min, and 40 °C/min) were fabricated (n = 5). Each specimen's shrinkage, translucency, flexural strength, hardness, and fracture toughness were determined. Two-way analysis of variance, Scheffé test, and Pearson's correlation analysis were used to evaluate data (α = 0.05).
RESULTS
The shrinkage (44.9 ± 3.1-47.5 ± 1.6 vol%) and flexural strength (74.1 ± 17.4-107.0 ± 27.1 MPa) were not affected by tested parameters (P ≥ 0.288). The interaction between the main factors affected the translucency, hardness, and fracture toughness of the specimens (P ≤ 0.007). Specimens with 770 °C final temperature and 70 °C/min heating rate had the lowest (21.8 ± 3.2 %) translucency (P ≤ 0.039). The hardness ranged between 4.98 ± 0.51 GPa (730 °C; 70 °C/min) and 5.60 ± 0.37 GPa (770 °C; 70 °C/min). Fracture toughness ranged between 0.54 ± 0.04 MPa√m and 0.67 ± 0.08 MPa√m with the highest values for specimens fired at 730 °C with 70 °C/min (P ≤ 0.001). There was a positive correlation between translucency and hardness (r = 0.335, P = 0.012), and a negative correlation between fracture toughness and all parameters other than shrinkage (translucency: r = -0.693/P < 0.001, flexural strength: r = -0.258/P = 0.046, hardness: r = -0.457/P < 0.001).
CONCLUSIONS
Heating rate and final temperature should be considered while fabricating veneered zirconia restorations with tested ceramic as they affected the translucency, hardness, and fracture toughness.
Topics: Temperature; Materials Testing; Heating; Pliability; Surface Properties; Zirconium; Ceramics; Dental Porcelain
PubMed: 37976995
DOI: 10.1016/j.jmbbm.2023.106235 -
Biophysical Journal Dec 2023The linkers of the nucleoskeleton and cytoskeleton (LINC) complex comprises Sad-1 and UNC-84 (SUN) and Klarsicht, ANC-1, SYNE homology (KASH) domain proteins, whose...
The linkers of the nucleoskeleton and cytoskeleton (LINC) complex comprises Sad-1 and UNC-84 (SUN) and Klarsicht, ANC-1, SYNE homology (KASH) domain proteins, whose conserved interactions provide a physical coupling between the cytoskeleton and the nucleoskeleton, thereby mediating the transfer of physical forces across the nuclear envelope. The LINC complex can perform distinct cellular functions by pairing various KASH domain proteins with the same SUN domain protein. Recent studies have suggested a higher-order assembly of SUN and KASH instead of a more widely accepted linear trimer model for the LINC complex. In the present study, we use molecular dynamics simulations to investigate the mechanism of force transfer across the two proposed models of LINC complex assembly, namely the 3:3 linear trimer model and the 6:6 higher-order model. Employing steered molecular dynamics simulations with various structures using forces at different rates and directions, we examine the structural stability of the two models under various biologically relevant conditions. Our results suggest that both models can withstand and transfer significant levels of force while retaining their structural integrity. However, the force response of various SUN/KASH assemblies depend on the force direction and pulling rates. Slower pulling rates result in higher mean square fluctuations of the 3:3 assembly compared to the fast pulling. Interestingly, the 6:6 assembly tends to provide an additional range of motion flexibility and might be more advantageous to the structural rigidity and pliability of the nuclear envelope. These findings offer insights into how the SUN and KASH proteins maintain the structural integrity of the nuclear membrane.
Topics: Nuclear Proteins; Membrane Proteins; Cytoskeleton; Nuclear Matrix; Nuclear Envelope
PubMed: 37924205
DOI: 10.1016/j.bpj.2023.11.001 -
Clinical, Cosmetic and Investigational... 2023High levels of VEGF and excessive angiogenesis contribute significantly to hypertrophic scar (HS) formation. Our study aimed to preliminarily investigate the effect of...
OBJECTIVE
High levels of VEGF and excessive angiogenesis contribute significantly to hypertrophic scar (HS) formation. Our study aimed to preliminarily investigate the effect of axitinib, a selective VEGF receptor tyrosine kinase inhibitor, on angiogenesis of HS and to explore its possible mechanism in a rabbit ear model.
METHODS
Ten male New Zealand white rabbits were used to establish HS models and then randomised to the control and axitinib groups. The scar tissues in the two groups were injected with axitinib or normal saline, and they were evaluated after one month of treatment. Macroscopic scar thickness, vascularity and pliability, as well as histopathological analysis including HE staining and Masson staining and scar elevation index (SEI) between two groups were compared. Immunohistochemical staining of CD31 in two groups was conducted to assess the degree of angiogenesis in HS tissue. The protein expression of protein kinase B (AKT) and ribosomal protein S6 kinase (p70S6K) and their phosphorylation levels in both groups were examined by Western blot analysis.
RESULTS
The macroscopic and histological observation showed intralesional axitinib injection significantly reduced scar thickness, vascularity and pliability of HS in the rabbit ear model. The value of SEI in HE assessment was also significantly declined in the axitinib group. Furthermore, immunohistochemical analysis revealed that axitinib suppressed the expression of CD31 in HS tissue, and the mean IOD for blood vessels was significantly lower in the axitinib-treated group. Additionally, axitinib effectively attenuated the protein expression of p70S6K, p-AKT and p-p70S6K by Western blot analysis.
CONCLUSION
Our study suggests that intralesional injection of axitinib can effectively attenuate HS by reducing angiogenesis in the rabbit ear model, and this inhibitory effect may be mediated by suppression of AKT/p70S6K signaling pathway. It indicates that axitinib may be a promising option for the treatment of HS in the future.
PubMed: 37901151
DOI: 10.2147/CCID.S430852 -
BioRxiv : the Preprint Server For... Sep 2023Basement membranes (BMs) are specialized sheets of extracellular matrix that underlie epithelial and endothelial tissues. BMs regulate traffic of cells and molecules...
Basement membranes (BMs) are specialized sheets of extracellular matrix that underlie epithelial and endothelial tissues. BMs regulate traffic of cells and molecules between compartments, and participate in signaling, cell migration and organogenesis. The dynamics of mammalian BMs, however, are poorly understood, largely due to a lack of models in which core BM components are endogenously labelled. Here, we describe the mouse, in which we fluorescently tag collagen IV, the main component of BMs. Using an innovative Planar-Sagittal live imaging technique to visualize the BM of developing skin, we directly observe BM deformation during hair follicle budding and basal progenitor cell divisions. The BM's inherent pliability enables dividing cells to remain attached to and deform the BM, rather than lose adhesion as generally thought. Using FRAP, we show BM collagen IV is extremely stable, even during periods of rapid epidermal growth. These findings demonstrate the utility of the mouse to shed new light on mammalian BM developmental dynamics.
PubMed: 37808687
DOI: 10.1101/2023.09.27.559396 -
PloS One 2023The study aims to identify whether factors such as time to initiation of laser therapy following scar formation, type of laser used, laser treatment interval and...
AIM
The study aims to identify whether factors such as time to initiation of laser therapy following scar formation, type of laser used, laser treatment interval and presence of complications influence burn scar outcomes in adults, by meta-analysis of previous studies.
METHODS
A literature search was conducted in May 2022 in seven databases to select studies on the effects of laser therapy in adult hypertrophic burn scars. The study protocol was registered with PROSPERO (CRD42022347836).
RESULTS
Eleven studies were included in the meta-analysis, with a total of 491 patients. Laser therapy significantly improved overall VSS/POSAS, vascularity, pliability, pigmentation and scar height of burn scars. Vascularity improvement was greater when laser therapy was performed >12 months (-1.50 [95%CI = -2.58;-0.42], p = 0.01) compared to <12 months after injury (-0.39 [95%CI = -0.68; -0.10], p = 0.01), the same was true for scar height ((-1.36 [95%CI = -2.07; -0.66], p<0.001) vs (-0.56 [95%CI = -0.70; -0.42], p<0.001)). Pulse dye laser (-4.35 [95%CI = -6.83; -1.86], p<0.001) gave a greater reduction in VSS/POSAS scores compared to non-ablative (-1.52 [95%CI = -2.24; -0.83], p<0.001) and ablative lasers (-0.95 [95%CI = -1.31; -0.59], p<0.001).
CONCLUSION
Efficacy of laser therapy is influenced by the time lapse after injury, the type of laser used and the interval between laser treatments. Significant heterogeneity was observed among studies, suggesting the need to explore other factors that may affect scar outcomes.
PubMed: 37756273
DOI: 10.1371/journal.pone.0292097 -
Cureus Aug 2023Background Cadaver dissection plays an important role in learning anatomy. A surgeon must have a thorough knowledge of anatomy of the operating region to perform safe...
Preparation of Soft Embalmed Cadavers by the Modified Thiel Embalming Technique for Surgical Skill Training and Development of a Universal Quantitative Scoring System to Assess the Suitability of Soft Embalmed Cadavers for Such Training Purposes.
Background Cadaver dissection plays an important role in learning anatomy. A surgeon must have a thorough knowledge of anatomy of the operating region to perform safe surgery. Skill laboratories give opportunities to surgeons to practice on cadavers before venturing onto real patients. The most common method of cadaver preservation is through formalin fixation. In the process of fixation, formalin destroys the tissue characteristics and also has issues such as smell, eye irritation, hardening of tissue, and risk of carcinogenesis. The Thiel embalming technique and its modifications were developed to address those issues. Our primary objective was to find the benefits of soft embalmed cadavers over formalin-fixed bodies and, secondly, to find out microbial flora in soft embalmed cadavers. Study design This is a basic study. Methods Four cadavers were prepared for the soft embalming purpose for our workshop for surgeons on spine fixation. Due to unavailability, we replaced 4-chloro-3-methylphenol 1% with phenol 1%. The bodies were preserved in refrigerators at 4C before being used for the workshop purpose. The delegates and faculties were given a questionnaire to assess their experience of the cadavers in terms of odor, irritation, tissue characteristics, joint mobility, and imaging characteristics. The results were calculated using statistical analysis. Swabs were taken from a few of the cadavers for culture to find the organisms. Results There were 14 questions in the questionnaire, and the data collected were divided into two groups, faculties, and delegates. JASP software was used to analyze the data. The questions addressed various aspects of cadavers such as color, odor, tissue pliability, joint flexibility, imaging characteristics, mucosal irritation, and earlier experience in working with cadavers. Cronbach α was used to find the correlation between the various characteristics analyzed. The authors intend to name the domains being measured: surgical suitability (scores of items 8 to 12), imaging suitability (scores of items 5 and 6), and smell score (scores of items 5 and 6). It can be a guide to constructing and refining a better quantitative scale to measure the "quality of soft-embalmed cadavers for surgical training." Conclusions Skill laboratories give opportunities to young surgeons and trainees to learn and improve their skills before applying them to real patients. This was our first attempt to develop soft embalmed cadavers at our center and our state. We used the parent solution with some variations as per the availability of chemicals at our place and found that the features of the preserved cadavers were good and well-suited to address our purpose. Therefore, with some variations in the parent formulations, centers situated in remote and less developed places can formulate their own solution to develop soft embalmed cadavers and establish cadaver skill laboratories. This will benefit the local surgeons and trainees. The authors tried to develop a few domains through statistical analysis, which can be used to assess and compare the quality of cadavers prepared at various centers.
PubMed: 37746418
DOI: 10.7759/cureus.43991 -
Indian Journal of Plastic Surgery :... Aug 2023Any injury involving the dermis will lead to scarring. Scar tissue can cause functional limitations, cosmetic impairments, pain, and itch. Adipose-derived stem cells...
Any injury involving the dermis will lead to scarring. Scar tissue can cause functional limitations, cosmetic impairments, pain, and itch. Adipose-derived stem cells have also been shown to play a role in scar modulation. This study evaluates changes in lipofilled scar over the period of time and compares it with non-lipofilled scar tissue. A prospective case-control study with intraindividual follow-up was performed on 30 adult patients with post-burn scars from November 2016 to May 2019. Clinical, histopathological, and immunohistochemical parameters were assessed among the case and control regions of the scar. Mean age of the study population was 30.6 years. The duration of the scar included in this study ranged from 1 to 28 years, with a mean duration of 5.91 years. There was a significant reduction in pain, itch, stiffness, and an increase in the pliability of the scar, and a substantial improvement in the modified Vancouver Scar Score in the lipofilled group. In histopathological analysis, the case group showed organized parallel collagen fibers, a significant reduction in melanocytes, improvement in vascularity, and a significantly increased amount of collagen fibers at the reticular dermis. Immunohistochemical analysis indicated new cell synthesis in the scar tissue and reduced melanocytes. The remodeling effect of adipocyte-derived stem cells is long-lasting, and there is a gradual improvement in most of the parameters. Lipofilling has regenerative capacity, which leads to the improved overall appearance of scar and improvement at the cellular level.
PubMed: 37705812
DOI: 10.1055/s-0043-1771515 -
Cureus Aug 2023Background Prolonged acne inflammation causes scar formation, one of which is post-acne keloids. Sebum, total cholesterol, and low-density lipoprotein (LDL) level can...
Background Prolonged acne inflammation causes scar formation, one of which is post-acne keloids. Sebum, total cholesterol, and low-density lipoprotein (LDL) level can influence post-acne keloids. This study aims to determine the association between sebum, total cholesterol, and LDL levels with post-acne keloids to better define the predisposing factors for this condition. Methods This study used primary data involving sociodemographics, clinical features, keloid classification, sebum levels, total cholesterol levels, and LDL levels in post-acne keloid patients at the Dermatology, Venereology, and Aesthetics Outpatient Clinics of Dr. Mohammad Hoesin General Hospital Palembang, Indonesia. Study samples were patients who fulfilled the inclusion and exclusion criteria by consecutive sampling. The data then underwent univariate and bivariate analyses to show the association between variables. Result A total of 22 patients with post-acne keloids participated. The subjects presented mostly with major keloids based on the classification (59.1%). The patients were predominantly 21-30 years old (50%) and male (90.9%). The keloids had onsets >six months to one year (45.5%), durations of one to five years (77.3%), and multiple presentations (68.2%). Vancouver Scar Scale (VSS) assessment showed mainly red vascularity (40.9%), mixed pigmentation (68.2%), >5 mm keloid height (59.1%), and firm pliability (40.9%). Most patients presented with pruritus (86.4%) but without pain (54.5%). Most had low levels of sebum (50%), normal total cholesterol (90.9%), and near-optimal LDL level (40.9%). There were no significant association between sebum (p = 1.000), total cholesterol (p = 1.000), and LDL (p = 0.376) levels with post-acne keloids. However, LDL levels above normal were most found in this study (68.2%). Conclusions There is no association between sebum, total cholesterol, and LDL levels with post-acne keloids. Despite the fact that LDL level was not statistically significant, there has been a rise in LDL level in the research subjects. Further research with a larger number of subjects and consideration of multicenter study through retrospective/prospective methods and complete lipid profile examinations is still required to provide a more representative study.
PubMed: 37692568
DOI: 10.7759/cureus.43096 -
Stress Biology Dec 2022In nature, organisms face multiple abiotic stress concurrently. Our previous study has indicated how threshold level of lethality depends on the type and combination of...
In nature, organisms face multiple abiotic stress concurrently. Our previous study has indicated how threshold level of lethality depends on the type and combination of stressors. Many mechanisms exist by which organisms respond to stressors and maintain homeostasis. We examined the homeostatic pliability in an extremophilic oriental midge Chironomus ramosus larvae under various combinatorial stress conditions of desiccation (DS), heat (HS) and starvation (SS). Exposure to these stressors led to activation of a common response pathway of oxidative stress. Abundance of antioxidant enzymes like superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase along with selective as well as stressor specific increase in total antioxidant capacity were reflected from the corresponding level of reactive oxygen and nitrogen species (RONS) in larvae exposed to various combinatorial stress. Additionally, we found stressor specific increment in lipid peroxidation level, protein carbonyl content and advanced oxidative protein products during the stress regime. Further investigation revealed a sharp decline in the activity of mitochondrial aconitase enzyme activity in response to abiotic stress induced oxidative stress. The combinatorial stressor specific comparative study based on biochemical and fluorescence based redox-endpoint assays confirmed that the generation of oxidative stress is the consequential convergent pathway of DS, HS and SS, but the quantum of RONS decides the redox potential of homeostatic response and survival rate.
PubMed: 37676561
DOI: 10.1007/s44154-022-00077-8 -
Advances in Clinical and Experimental... Apr 2024Available statistical data from 2015 show that 28% of pregnancies in developed countries end in cesarean section (CC). Discomfort associated with the scar after surgery...
BACKGROUND
Available statistical data from 2015 show that 28% of pregnancies in developed countries end in cesarean section (CC). Discomfort associated with the scar after surgery is a common complication.
OBJECTIVES
This study aimed to evaluate the changes in the structure of the cesarean scar after the application of a scheme of manual therapy.
MATERIAL AND METHODS
The study included 15 women in the treatment group (TG) and 15 in the control group (CG). The scars were evaluated twice at 5-week intervals with the use of quantitative scales: the Vancouver Scar Scale (VSS), the Manchester Scar Scale (MSS) and the Patient and Observer Scar Assessment Scale (POSAS). During each examination, the scar was compared, using the specified criteria, to the physiological skin, i.e., the tissues directly bordering the incision. During therapy, 8 manual techniques were used during a 4-week program consisting of 30-minute sessions 3 times per week.
RESULTS
Patients in the TG showed a statistically significant improvement in all of the analyzed characteristics of the scar. A statistically significant difference was also observed between the results obtained during the 2nd examination (after the therapy) in the TG and the CG.
CONCLUSIONS
As a result of the therapy, the condition of the scar in the TG significantly improved. Onerous scar-related symptoms were alleviated. The vascularity, hyperpigmentation and distortion of the scar were reduced. The elasticity and pliability of the scar increased, and the height of the scar decreased. The texture, finish and contour of the scar improved. Obtained results suggest that manual therapy of the scar after CC should be a part of the treatment in women during the postpartum period.
Topics: Humans; Female; Cesarean Section; Cicatrix; Adult; Musculoskeletal Manipulations; Pregnancy; Treatment Outcome
PubMed: 37665082
DOI: 10.17219/acem/169236