Drilling mud’s rheological characteristics, such as plastic viscosity and yield point, are adversely affected with an inappropriate mud formulation. Native starch is one of the most important components in water-based mud because it improves the rheological and filtration characteristics of the mud. The native starch stability under various temperature and exposure time regimes is an important concern for utilizing starch in oil and gas drilling operations. In this work, tapioca starch was modified using carboxymethylation for the first time in order to improve its performance in non-damaging water-based muds. The modified starch was characterized by Fourier-transform infrared spectroscopy and X-ray diffraction. The thermal stability was tested using thermal gravimetric analysis. Various mud blends were formulated based on the experimental design using response surface methodology (RSM) to investigate their performance at various temperature conditions. Thirty experimental runs were carried out based on the selected factors and responses considering the optimal (custom) design, and the results were analyzed through ANOVA. The Fourier-transform infrared spectroscopy and X-ray diffraction results confirmed the carboxymethylation of starch. The TGA analysis revealed strong thermal stability after modification. Additionally, the Power law model (PLM) described the obtained rheological data for the selected formulations, resulting in determination coefficients of more than 0.95. Furthermore, the examined samples showed a reduction in the flow behavior index from 0.30 to 0.21 and an increase in the consistency index from 5.6 to 15.1. Optimization and confirmation results revealed the adequacy of the generated empirical models for both plastic viscosity and yield point. The obtained consistency index values provided a direct relationship with the modified starch concentration, indicating an improvement in the cutting carrying capacity of mud. Based on the current literature survey, the studied formulation has not been reported in the literature. Water based muds have been used in the oil and gas drilling industry for decades. A multi-functional drilling mud is required to perform numerous important functions including transporting cuttings, suspending cuttings, controlling formation pressure, cooling, and lubricating the bit, minimizing corrosion, providing necessary hydraulic power to down-hole equipment, and reducing formation damage. These functions can be achieved with mud exhibiting significant rheological and filtration properties. Rheological properties are influenced by various factors including solid content, pH, and additives such as dispersants, surfactants, and polymers ,2,3,4.The selection of proper mud additives is very important for a successful drilling operation. Numerous mud additives including viscosifiers, inhibitors, pH and fluid loss control agents are the primary additives used in water-based muds. For drilling the payzone section, a drilling fluid consists of polymers and other functionalized additives that are used to avoid the excessive fluid losses into the formation. Generally acid soluble materials including starches, polymers, and calcium carbonates are used to enhance the rheological and filtration properties of the mud ,6. StarcThe inadequate functional characteristics of native starches in water-based muds limit their applications owing to certain limitations such as their poor thermal stability, solubility, and bacterial resistance ,9,10. ThIn recent years, various starches have been modified chemically which substituted the imported drilling fluid additives. The modified starches exhibited better rheological and filtration properties in bentonite suspensions ,14,15,162COOH). It is a process in which starch hydroxyl groups react with monochloroacetic acid (MCA) or Monochloroacetate in the presence of a strong alkali. Several commonly used starches have been modified through carboxymethylation for different food and industrial applications. Carboxymethyl potato and corn starches have been employed largely for rheology improvements, filtrate control in drilling muds, drill-in, completion, and workover fluids [Out of all the methods, carboxymethylation is one of the most-used starch modification techniques in which the starch molecule’s -OH groups are partially substituted by the ether group , polyanionic cellulose , and xanthan gum  were used for drilling mud formulations. All the materials were used as provided without further treatment.For carboxymethylation, monochloroacetic acid  and sodium hydroxide  were used. Methanol (99%), ethanol (HMBG: 95%), and acetone  were used as solvents for modification purposes. Other additives including calcium carbonate . For carboxymethylation, a previous method by Rachtanapun, et al.  was follw/v) sodium chloride solution and titrated with 1 M NaOH. The DS was evaluated using the following equations.DS is the degree of substitution; oM represents the molar mass of the AGU (g/mol); RM is the molar mass of carboxymethyl residue (g/mol); nNaOH is the amount of NaOH used (mol); pm is the weight of the polymer taken (g); cm is the corrected weight of the polymer (g); and F is the percentage of moisture.The number of functional groups introduced into the anhydro glucose unit (AGU) is defined by the degree of substitution. Since every AGU has four hydroxyl groups and the value of DS lies in the 0–3 range. Here, the degree of substitution was measured using the direct titration method, which is the most popular chemical assessment technique that can give an accurate assessment of the DS. For DS determination, accurately pre-weighed (5 g) carboxymethylated starch was dispersed in 150 mL acetone, and then 15 mL (5 M HCl) were mixed with the suspension and agitated for 30 min. In this step, the Na-CMS was converted into H-CMS (protonated CMS). The product was rinsed with 80% methanol multiple times until the pH became neutral. The mixture was filtered, immersed in acetone, and stirred for a further 15 min. Finally, the dispersion was filtered and dried for 24 h at 50 °C. A total of 2 g of CMS were dissolved in 1% , X-ray diffraction, and thermogravimetric analysis (TGA) were used.−1 to obtain the percentage of absorbance. The infrared spectroscopy detected the vibration characteristics of chemical functional groups in the samples. Likewise, the X-ray diffraction pattern of native tapioca starch and its carboxymethylated form were recorded with the XRD instrument . The XRD is a fast analytical method for identifying phases in crystalline materials. The operating conditions were maintained at 40 kV and 40 mA. Scanning was performed from 5 to 80° (2θ). The XRD analysis software (X’Pert HighScore Plus) was utilized to obtain the crystallinity of the NTS and CMTS. The thermal stability of the modified starch was quantified with a thermogravimetric analysis instrument  in the nitrogen atmosphere. It is a significant design parameter when selecting drilling mud additives. During testing, 5 mg of powdered starch sample was loaded in an alumina container followed by heating at a heating rate of 10 °C/min under N2 at 20 mL/min from 30 °C to 800 °C.To analyze the chemical structure of native and carboxymethylated starches, the dried specimens with certain amounts were mixed with KBr and pressed into a transparent disk. The FTIR analysis was carried out using the FTIR spectroscopy instrument . Samples were analyzed by scanning the wavelength between 4000 and 400 cmDesign Expert software v 13.0.1.0  was used in this work to create the experimental design and analyze the results using the response surface methodology (RSM). The RSM is a user-friendly statistical tool for designing, analyzing, optimizing, and validating experimental findings . An optiX1, X2, …, nX. The general relationship between response parameters and input process parameters is described by:f represents the real response function, and error describes the differentiation.The process performance was assessed by evaluating the responses based on the input factors β is the regression coefficient; i and j are the linear and quadratic coefficients, respectively; k represents the number of examined factors and optimized by the experiment, while e represents the random error.The quadratic equation model of the response Y derived as a function of the levels of independent variables expressed according to Equation (4) was used to predict optimal conditions. It is a second-order polynomial equation model for predicting the optimum point between factors and responses .(4)Y=βoBased on the selected design, thirty (30) experimental runs were performed for rheological analysis. Randomized experiments were carried out to eliminate errors caused by systematic patterns in the variables. Moreover, each experimental run was carried out three times, and an average of the results was reported.The mud samples were formulated considering the API recommended practices. The muds were prepared according to the experimental design described in the previous section. The mud additives were mixed using a high-speed Fann Multimixer to prevent the degree of lumps formation within the mud system. A mixer cup was filled with 350 mL of deionized water followed by adding 1.5 ppb of xanthan gum (XG). The product was mixed at 11,500 rpm for 20 min to ensure a homogenous mixture. The pH was maintained at the API recommended range (9.5–10) by adding sodium hydroxide. The modified starch and polyanionic cellulose (PAC) as a rheology enhancer as well as a fluid loss control agent were added and mixed again for 20 min. Finally, 115 ppb of calcium carbonate was added to the mixture to achieve the required mud weight. The mixture was mixed for a further 20 min. The additives used in the mud preparation are summarized in To examine the thermal stability of the formulated muds, the prepared samples were kept for 16 h in a hot roll oven (Fann roller oven) at selected temperature conditions . It provided an excellent approach of aging drilling mud samples at higher temperatures. The aging cells containing mud samples were pressurized to 1000 psi pressure and were subjected to the defined temperature while agitating on power driven rollers. After the hot rolling, the rheological properties were tested and recorded.R600 and R300 are the dial readings at 600 and 300 rpm, respectively. PV and YP are the plastic viscosity (cP) and yield point (lb/100 ft2), respectively.The drilling fluid’s rheological properties influence a variety of drilling parameters including cuttings carrying capacity, hole cleaning, and pressure drop control. These are the most important aspects monitored throughout the drilling process. Thus, extra attention should be paid while determining these parameters. The rheological properties of all the fluid samples were evaluated in compliance with the American Petroleum Institute (API) standards using the Fann V-G meter 35SA . Equatio−1, respectively. To obtain a homogeneous fluid, the samples were agitated for 5 min before performing each experimental run.Shear stresses and viscosities were computed at two rotational speeds of 600 and 300 rpm, which correspond to a shear rate of 1021.38 and 510.67 s2 values for all the developed models were used to analyze the quality of fit. The equations derived from a regression analysis of experimental results were applied to develop response surfaces and were reported. The model’s statistical summary is given in The rheology of a drilling fluid is dictated by the fluid’s shear stress and shear rate relationship. To analyze which model is most suitable for the drilling muds, the shear stress over a range of shear rates was measured using the Discovery Hybrid Rheometer (Model: DHR-1). The rheological properties of the mud samples were evaluated, and the obtained results were used to evaluate their fitness with the conventional models. In this study, Bingham plastic, Power law, and Herschel–Bulkley models were employed to study the shear thinning tendency of the formulated muds. In addition, regression equations have been obtained by applying RSM for rheological properties, namely PV and YP. In order to explore the influence of selected variables and their interactions on responses, the obtained models were analyzed to test their adequacy by using ANOVA. Finally, the system was optimized and validated by further experiments to obtain the optimum rheological parameters values for a bentonite-free mud system. Rw/v). It was used in the process to initiate the reaction. w/v) with a maximum substitution degree of 0.77 and reaction efficiency of 71%. A higher concentration reaction with NaOH facilitates the swelling of starch granules and develops more starch-O-Na, culminating in a much greater risk of carboxymethylation in the starch molecules with the OH group. However, during carboxymethylation, it was observed that the reaction efficiency decreased above 15% of the NaOH concentration due to the dominant side reaction of NaOH with MCA. The degree of the substitution value was then lowered by raising the NaOH concentration above 15%. Similar findings were also reported for sago starch carboxymethylation by Yaacob, et al. [In this study, two parameters were examined including the sodium hydroxide concentration and MCA molar ratio. Starch carboxymethylation was conducted at varying aqueous sodium hydroxide concentrations ranging from 10 to 35% , the prominent absorption peaks for asymmetric and symmetric COO- vibrations were found in the carboxymethyl starch spectra at about 1648 and 1611 cm−1. This result is in agreement with the study of Liu, et al. [2COO- group was introduced into the starch molecule. This carbonyl double bond indicates the presence of a carboxyl group in the studied sample. These bands confirmed the carboxymethylation modification of the native tapioca starch.Starch carboxymethylation has resulted in the emergence of new bands and has affected the intensity of native starch characteristics. The measurements confirmed the desired modification performed on the starch. The FTIR spectra of native and modified starch (DS 0.64 and 0.77) are shown in , et al. . This boThe crystalline structure of the carboxymethylated tapioca starch (CMTS) was investigated with XRD measurements. X-ray diffractograms of native and modified tapioca starch samples are presented in The thermal stability of NTS and CMTS was determined by thermogravimetric analysis (TGA). TGA and DTG curves for NTS and CMTS are presented in In the current study, for NTS, the first weight loss (≈6%) commences around 30–70 °C and may be because of the residual solvents which are left after washing. The second weight loss starts at 70 °C and ends at 160 °C, corresponding to 4% which is because of the moisture content and the loss of water from starch. It is due to the dehydration reaction between the hydroxyl groups in NTS. The third and main degradation stage starts at a range of 250–320 °C. The DTG curves also showed the maximum weight loss at about 300 °C for native starch.The TGA and DTG curves for CMTS show two degradation stages; the first weight loss at around 30–130 °C is because of water, and the second weight loss at 250–365 °C corresponds to the degradation and decomposition of the starch structure. The first weight loss corresponds to a total of 20%, and the second weight loss is 60%. It is worth mentioning that the maximum weight loss for CMTS starch has shifted to a higher temperature (above 300 °C), which shows that the thermal stability of starch has increased after carboxymethylation. Similar observations have been found by other authors, Ren, et al. . In natiIt is vital to understand the correlation between shear stress and the shear rate in order to analyze the behavior of a drilling mud and its potential to suspend and carry drilled cuttings. The development of an appropriate rheological model is essential for a comprehensive description of the rheological properties of drilling muds. Drilling fluids are non-Newtonian in nature, showing a non-linear relationship between shear rate and shear stress. In this work, three mud blends including CMTS 0 (Control), CMTS 1, and CMTS 5 were selected for rheological modeling. In the first blend, no CMTS was added, while in CMTS 1 and CMTS 5, the concentrations of 1 ppb and 5 ppb were added. The rheometer readings in terms of shear stress and shear rate were plotted and are presented in 2 values of 0.99, 0.97, and 0.99 for CMTS 0, CMTS 1, and CMTS 5, respectively. The flow behavior indices for the samples were 0.30, 0.23, and 0.21, while the consistency indices were 5.6, 12.2, and 15.12 for CMTS 0, CMTS 1, and CMTS 5, respectively. From the obtained data, it was noticed that the value of the flow behavior index was reduced with an increase in the CMTS concentration. On the other hand, the introduction of starch enhanced the consistency index of the blends.The obtained modeling parameters of each model are given in 2 value to be less than 0.80 when fitted with the Bingham model. The n and k values for all the mud blends showed almost the same behavior of pseudoplasticity  were fitted with the experimentally obtained data to opt for the most appropriate regression equations. In X1 and X2 represent the CMTS concentration and temperature, respectively.The model selection has been made as suggested by the RSM tool. In terms of coded factors, the obtained final equations are given below:p-value  of <0.05, each independent factor’s effect was considered significant. The p-value represents each regression coefficient’s significance . The significance of the regression coefficient is inversely related to the p-value. The model adequacy was further evaluated through an analysis of variance. Here, the quadratic and cubic regression coefficients, as well as the correlation between the variables in the model, were calculated. At a 2”, can have high levels of multicollinearity which validates the regression models. In the current work, the standard deviation and coefficient of variation of the model were insignificant; thus, the models were considered adequate to predict the rheological properties of the formulated mud, with an acceptable adjusted R2 value. The R2 and adjusted R2 values are given in It is considered that the model with a higher coefficient of determination value, “R2 of 0.896 is in close agreement with the adjusted R2 of 0.922, suggesting that the difference is <0.2. Besides, the adequate precision which measures the signal to noise ratio for plastic viscosity was found to be 28.88, which is higher than 4, which is desirable. Hence the generated model can be applied to navigate the design space. Likewise, for the yield point, the predicted R2 of 0.947 is in reasonable agreement with the adjusted R2 of 0.983; i.e., the difference is <0.2. Moreover, the adequate precision for the yield point was reported to be 42.04. Thus, the generated model for YP can be considered appropriate for the design space. These findings were in close agreement with the results reported by Betiha, et al. [Here, for the plastic viscosity, the predicted R2 = 0.93). This showed that the generated regression models can efficiently describe the relationship between the factors and the responses in the studied range. Since the data points are uniformly spread close to or on a straight line, the error is thus negligible within the operational parameter boundaries.The adequacy of the generated models was also investigated using residuals. It is the difference between the observed and predicted responses. This analysis was accomplished using the normal probability plots as well as residual vs. predicted plots. Plastic viscosity and the yield point are believed to be the most essential rheological parameters of drilling muds. The CMTS concentration was observed to influence the performance of the drilling mud formulations significantly. 2, while at the same temperature, CMTS showed an improved YP of 19 lb/100 ft2. It is worth mentioning that the optimum YP values of the CMTS based mud blends remained in the range recommended by API standards.Similarly, the potential of the drilling mud to take the drilled cuttings from the annulus can be determined by the YP values, which should be fairly strong for the proper transport of the cuttings. It is an indicator of the drilling mud’s thixotropic characteristics at flow conditions, and its value can be regulated using different chemical additives. High YP values, however, produce additional pump pressure which should be prevented. Under flowing conditions, the yield strength is dependent on the electro-chemical charges in the drilling fluid. After evaluating the impact of each factor on the selected responses, numerical optimization was performed to generate a combination of factors using the software. The range of the factors (CMTS concentration and temperature) was set between lower and upper levels, which were coded to cover a broad range. All the factors were ranged, while a target for PV was set as 15 cP. id) that range from 0 (least) to 1 (most). The following equation was used for the desirability function.n is the number of responses.The desirability function (D) was applied to define an appropriate solution to establish the optimal conditions. The overall desirability (D) is the geometric (multiplicative) mean of all individual desirabilities  and monochloroacetic acid (MCA) concentrations have a significant effect on the modification of starch granules. FTIR analysis confirmed the modification by showing new bands of carboxymethyl group. The crystallinity of the samples was reduced after carboxymethylation when compared with the native starch. The thermal stability of starch was enhanced after modification, resulting in a better performance at higher temperatures with acceptable rheological properties. The mud formulated with modified starch showed shear thinning behavior, and shear stress was increased with the addition of the CMTS concentration into mud. The plastic viscosity and yield stress of mud blends showed a negative relationship with temperature which was due to the degradation of additives when exposed to high temperatures. The mud blends were tested for conventional rheological models which showed best fitting with the Power law model having the R


Background and Objectives: Dentin grafts have osteoinductive and osteoconductive properties and are considered as an alternative to autogenous graft. This study evaluates the efficacy of autogenous mineralized dentin graft (AMDG) alone or with xenograft and compares it with those of various graft materials used in the treatment of intraosseous bone defects. Materials and Methods: The third incisor teeth of six sheep (2–3 years old) were extracted and AMDG was obtained. Six defects were prepared on each tibia of these six sheep: empty defect (group E); autogenous graft (group A), dentin graft (group D), xenograft (group X), autogenous + xenograft (group A + X) and dentin + xenograft (group D + X). Three sheep in each group were sacrificed in the post-operative 3rd and 6th week and the histologic analyses were performed. Results: The D and D + X groups showed histological features similar to the other groups in the 3rd and 6th weeks. No statistically significant difference was found regarding the rates of new bone formation between the D and D + X groups (p = 1.0) and the other groups at both time intervals (p > 0.05). Conclusions: Similar results observed in this study between groups A, D, X, A + X and D + X demonstrate that AMDG can be successfully used in the treatment of intraosseous bone defects. Further experimental and clinical studies are needed to be able to evaluate the effectiveness of dentin grafts in different types of indications. Different types of graft materials are used in the treatment of alveolar bone defects, socket preservation techniques for maintaining the postextraction socket volume and bone augmentation techniques used before or after implant surgeries. Osteogenesis, osteoinduction and/or osteoconduction mechanisms are used to manipulate the regenerative potentials of bone grafts . OsteogeThis histologic and histomorphometric experimental study aims to evaluate the effectiveness of the use of autogenous mineralized dentin grafts alone or combined with xenografts on intraosseous bone defects to be compared with the use of autogenous graft, xenograft and combination of the two that have frequent use in clinical practice.This experimental study was conducted on six male sheep with an average age of 2–3 years and an average weight of 53.36 ± 2.89 kg. The study protocol was approved by the Animal Experimentation Ethics Committee of the ˙Mehmet Akif Ersoy Experimental Research Development and Education Center . We conducted all procedures according to the international ethical guidelines for the welfare and treatment of experimental animals. This manuscript was prepared according to the guidelines proposed by ARRIVE .d = 1.818, and the sample size was determined as n:6 for each group to obtain 80% power at the α = 0.05 level. For the study, a total number of 72 defects (36 defects for the 3rd week group and 36 for the 6th week group) were determined.In order to determine the sample size power analysis was performed using the G*Power (v3.1.9.2) program. For the new bone formation parameter, a minimum difference of 20% between the two groups was predicted to be clinically significant. The effect size was calculated as ®, Adeka, Istanbul, Turkey). Intraoral local anesthesia  was administered then right and left lower third incisor teeth were extracted (http://www.randomizer.org/ accessed on 9 December 2021). M ineralized dentin graft (Group D), xenograft , autogenous bone graft ), a mixture of 50% mineralized dentin graft and 50% xenograft (Group D + X) and a mixture of 50% autogenous bone graft and 50% xenograft (group A + X) were applied to the prepared defects. One defect was left unfilled as a control   collagen membrane was cut into two and all defects were covered and pinned  with a collagen membrane.  after graft application. Subcutaneous tissue and skin were closed primarily with number 0 resorbable sutures .The animals were fasted 24 h prior to the surgical operation. Following their admission to the operating room, they were intramuscularly administered a combination of atropine sulfate , xylazine  and ketamine hydrochloride . Vascular access was established to administer Ringer’s lactate i.v.  at a rate of 5 mL/kg/h after sedation achieved. The animals were transferred to the operating room table, intubated and further anesthetized by administration of 2% isoflurane (Isofluranextracted . The anixtracted . The typGroup E) . The 30 embrane. . The perThe enamel and cement layers of the extracted teeth were removed with a dental handpiece . The teeTibias were stabilized with Robert Jones bandage against the risk of fracture at the end of the surgeries. On the 4th day after the surgery, the Robert Jones bandage was removed and the hypochlorous acid  was applied topically to the wound area twice a day for 5 days.30 min before coming out of anesthesia and for 5 days after the operation, the sheep were administered an intramuscular injection of 0.5 mg/kg analgesic meloxicam . A dosage of 20 mg/kg ceftriaxone antibiotic  per day was injected into the animals for 5 days to prevent postoperative infection. During the recovery period, the experimental animals were kept in cages separately and their care and general health check were carried out routinely. The cleaning of the living space and the feed and water needs of the animals were provided by the service staff of Mehmet Akif Ersoy Experimental Research Development and Education Center.The animals were sacrificed randomly on the third and sixth week of the experiment, three of them at a time. A dosage of 50 mg/kg of 10% sodium pentothal solution was used to intravenously euthanize the animals after they were administered xylazine and ketamine to be anesthetized. Following the removal of the soft tissues with dissection, the remaining hard tissues were placed into 10% buffered formalin.Histologic and histomorphometric evaluations were conducted with single blinded histologist (M.S.T.). The defects were fixed in 10% buffered formalin for a week and then decalcified in a solution of one part of 50% formic acid and one part of 20% sodium citrate. Sagittal sections of defect areas from decalcified pieces were embedded into paraffin blocks. Sections of 5–7 μ were extracted, stained with hematoxylin-eosin (H&E) and examined under light microscope 10× and 20× magnification . Histomorphometric evaluations of new bone formation and residual graft materials were also performed. Images of the chosen areas of each defect were taken at 10× under the same microscope and then computerized. These operations were performed by a camera  connected to the microscope and a computer. The images were processed by the ‘Olympus Soft Imaging System Analysis Five’ (Olympus Corporation) software on the computer to measure the area occupied by bone regeneration and residual graft, and the measurements were compared with the total area. Necrosis and foreign body reaction were graded as 0:no sign, +: existing. Inflammation was scored as 0 (absent), 1 (mild), 2 (moderate) and 3 (severe).p < 0.05.NCSS  2007  software was used for statistical analyses. Descriptive statistical methods  were used to evaluate the results of the study. Shapiro–Wilk test and graphical examinations were used to measure the consistency of the means of quantitative data with normal distribution. Mann–Whitney U test was used for the comparison between two groups of quantitative variables with abnormal distribution and Kruskal–Wallis and Dunn–Bonferroni tests were used for comparisons between groups more than two. For qualitative data comparison, Pearson’s chi-squared and Fisher–Freeman–Halton exact tests were used. Statistical significance was considered to be No signs of infection, fracture, or wound site opening were observed in the experimental animals. Three experimental animals were sacrificed on the 3rd week and the other three on the 6th week. Histologic and histomorphometric examinations on a total of 72 defects were conducted.No signs of necrosis or foreign body reaction were observed in any groups on the 3rd and 6th weeks.p = 0.999 on the 3rd and 6th weeks).Inflammation was observed on the 3rd week in two defects in group D and one defect in each other; while it was present in one defect in each group on the 6th week. There was no difference between the groups in inflammation scores on the 3rd and 6th weeks .p = 0.030; p = 0.045; p = 0.024; p = 0.001; p = 0.001), respectively). Similarly, group A was measured to have statistically significantly lower rates than that of group A + X . There was no statistically significant difference between other groups (p > 0.05).Increased new bone formation areas from the edges to the midsection of defects were observed on the 6th week a–f. The The evaluation of the amount of residual graft in groups D, X, A + X and D + X .p < 0.001). There was no statistically significant difference between the other residual graft amounts on the 3rd week. There was a decrease in the amount of residual graft on the 6th week compared to the 3rd week. Group X was observed to have higher rates than those of groups D and X + A .The lowest amount of residual graft on the 3rd week was observed to be statistically significantly lower in group A + X (15.83 ± 1.23) than in group X (p < 0.005), whereas it was %77.18 ± 0.76 for the test group and %58.92 ± 0.32 for the control group on day 90, which is also statistically significant (p < 0.05). Similar results were achieved in our study. The new bone formation ratios of the dentin grafts in both time periods were found to be statistically significantly higher than the empty defect group. Mineralized dentin grafts are reported to be usable for socket protection techniques in oral implantology, intraosseous bone defect treatment and sinus lifting operations [This study evaluates the histological and histomorphometric efficacy of autogenous mineralized dentin graft alone or mixed with xenograft and compares it with those of various graft materials used for the treatment of intraosseous bone defects. The results were compared with those of the defects that were filled with autogenous graft, xenograft or both which are frequently used in clinical routine. No statistically significant difference was found between the groups where mineralized dentin graft was used alone (group D) or with xenografts (D + X) and the groups of autogenous graft (A), xenograft (X) and autogenous + xenograft (A + X) in the evaluations made on the 3rd and 6th weeks. The new bone formation ratio in the empty control group (E) was found to be statistically significantly lower than other groups in both time periods. To the best of our knowledge, this is the first study ever made in which mineralized dentin graft, autogenous graft, xenograft and their combinations were all compared in the same experimental model. Despite having high osteoinductive properties, the autogenous grafts are frequently used in combination with other grafts in large defects due to being clinically laborious to obtain, having limited obtainability and relatively short resorption time . It is rerations ,34,35. Perations  publisheerations , Chang a®) 2–4 weeks after tooth extraction. No statistically significant difference was found with regard to new bone formation between the two groups in the postop 6 months . The residual graft was found to be %8.95 ± 6.15 in AutoBt and %17.08 ± 16.57 in Bio-Oss (p = 2.45). In our study, we achieved similar values for the new bone formation ratios of xenograft and dentin graft, and for residual graft amounts as well.Dentin grafts can be prepared mineralized or demineralized. Demineralization reveals collagen matrix and growth factors get released, resulting in an increase in regenerative capacity ,37. HoweThis experimental study was planned to be performed on sheep to compare different types of graft materials on the same model. Because working on sheep has advantages, such as having bone tissue and remodeling similar to those of humans, being frequently used in bone healing studies because of the possibility to prepare numerous relatively large defects on the same animal and being suitable for working on large defects ,41. WhilThe age and gender of the experimental animal may affect bone metabolism. Therefore, young (2–3 years old) sheep were included in the study. In order to act in compliance with ethical rules and not to harm any experimental animals, the right and left lower third incisor teeth of the sheep were extracted. To prevent any fractures in animals’ tibias and because only two teeth were extracted, defects with 6 mm diameter were prepared to obtain dentin graft with enough volume. Our study reveals that defect diameters were appropriately determined because the least amount of new bone formation was observed in empty defects. Two time periods were determined in our study to be able to evaluate the early and late term healing. Due to shorter recovery period in sheep, sacrifices were performed on 3rd and 6th weeks. Studies with long-term follow-up that will evaluate the long-term change in graft volume will prove useful. In implantology, dental implant operations are performed in conjunction with or after the augmentation operations. This study aimed to evaluate the efficacy of mineralized dental graft, therefore, dental implants were not applied to graft areas. In future studies, it will be useful to apply different graft combinations to defects and following a proper healing period to apply dental implants to evaluate bone-implant contact.The results of this experimental study conducted on the sheep reveal that the success of autogenous mineralized dentin grafts in the treatment of intraosseous defects is similar to that of autogenous bone, xenograft, autogenous + xenograft and dentin + xenograft. Further experimental and clinical studies are needed to be able to evaluate the effectiveness of dentin grafts in different types of indications.


We describe a case of sac enlargement that occurred 11 years after emergent open surgical repair of an infected abdominal aortic aneurysm. The diameter of the sac covering the Dacron graft had gradually expanded to 80 mm, and the flow of contrast medium into the sac was suspected. Elective surgery revealed a perigraft seroma and back-bleeding from the remnant wall. After attaining hemostasis, fibrin glue and oxidized cellulose were applied, and sac plication was performed. Thereafter, the sac has not expanded. Open diagnostic treatment should be a good option for cases of postoperative sac enlargement with an unknown origin. Sac dilation after open abdominal aortic aneurysm (AAA) repair has been reported and is mainly caused by perigraft seroma (PGS) or hygroma; additional causes include infection and bleeding.A). A rifampicin-soaked Dacron bifurcated graft  was placed in situ, and the aneurysmal wall excepting the posterior wall was removed. The graft was wrapped with the omentum and the posterior wall. No causative microorganisms were detected in the cultured specimens or pus. Although the patient’s chronic kidney disease worsened postoperatively, she was discharged uneventfully. One year later, hemodialysis was started. Five years after the index operation, follow-up computed tomography (CT) findings revealed the presence of a 40-mm sac, and a diagnosis of PGS was made (B). The radiodensity of the collected fluid did not exceed 30 Hounsfield units. For the next 4 years, the sac, including the graft, was stable. Nine years after the index operation, coronary artery bypass surgery was performed for angina, and anticoagulant therapy was started for atrial fibrillation. In the following 2 years, the sac grew by approximately 20 mm/year, ultimately reaching 80 mm in diameter.A 77-year-old woman with slight abdominal discomfort was admitted to our department for investigation and treatment of an 80-mm sac. She had undergone open AAA repair 11 years ago for impending rupture of an infected AAA , A. A riwas made , B. The 2). A mass in the lower abdomen was palpable but not pulsatile. Owing to arteriosclerosis, the pedal pulses were poor. The routine blood test results were unremarkable, and there were no clinical findings of inflammation or infection. The patient’s general condition was sufficient for open surgery. Contrast-enhanced CT scans showed that the sac was filled with low-density fluid, with the contrast medium flowing into the sac in the late phase (C). We suspected that the sac enlargement was caused by back-bleeding from the posterior wall, PGS, or infection. We opted to perform elective open surgery, considering the graft replacement, if necessary, because of the presence of abdominal discomfort, sac enlargement, bleeding, and risk of rupture. We did not select a percutaneous drainage, which could have led to the recurrence of PGS. Endovascular therapy is not considered appropriate in cases where the cause of the sac dilation is infection and where the main content of the sac is not blood; therefore, coagulation after embolization was not expected. Moreover, the patient had no proper access sites because of severe arteriosclerosis.On physical examination, the patient was 152 cm tall and weighed 45.4 kg . Puncturing of the sac released 200 mL of a slightly turbid, straw-colored fluid followed by hemorrhagic fluid, resulting in the collapse of the sac. We incised the sac without clamping the aorta. A gelatinous material on the surface of the graft and minor bleeding from the omentum and posterior wall surrounding the graft were observed (B). The graft was not dilated or attached to the omentum or posterior wall. There was no sign of bleeding at the anastomoses or extravasation through the graft. Our diagnosis was PGS accompanied by minor bleeding from the remnant sac, and graft replacement was considered unnecessary. After achieving hemostasis via cauterization and ligation, fibrin glue and oxidized cellulose were applied around the graft (C). The blood loss was 130 mL, and the operating time was 131 minutes.A midline laparotomy was performed, and the intra-abdominal adhesions were separated. The sac was soft but not pulsatile , A. Puncobserved , B. The he graft . Subsequhe graft C. The bD).Cytological examination indicated bleeding and inflammation. The cultures of the fluid sample were negative. Contrast-enhanced CT findings on postoperative day 4 confirmed the shrinkage of the sac and the absence of contrast medium entry into the sac. The patient was discharged on postoperative day 11 without the abdominal discomfort. There was no sac dilation found at 3 years after the laparotomy , D.,,11The causes of postoperative sac enlargement include PGS, infection, anastomotic aneurysms, transinterstitial bleeding through the graft, and minor bleeding from the sac.,,,,,,Seromas have been reported in patients with polytetrafluoroethylene (PTFE) and Dacron grafts; those after open AAA repair are mainly attributed to the PTFE grafts (approximately 20% of the expanded PTFE grafts) instead of the Dacron grafts 0%-3.8%)..8%.3 The4,,In our case, PGS was diagnosed before admission because the radiodensity of the fluid within the sac was low and the sac had been stable.It should be considered that sac enlargement after open AAA repair can involve not only PGS, but also minor bleeding from the sac. In this endovascular aortic repair era, follow-up examinations after open AAA repair should include contrast-enhanced CT or duplex ultrasound examination to rule out any endoleak-like events. Open surgery or endovascular therapy can be selected according to the symptoms, size of the sac, and mechanism of sac enlargement.


The reconstruction of deep nasal ala defects can be challenging. The often thick, sebaceous skin of the nose provides structural support helping maintain the ala shape and nasal patency; loss of this support may result in ala deformity and nasal vestibule collapse. Traditional full-thickness skin grafts of deep alar defects may result in depressed scars. We present a variation of the full-thickness skin graft to repair deeper alar defects, sculpting the graft into a boat-shaped or “navicular” form. This allows for sufficient volume restoration and good cosmesis while avoiding more extensive surgical repairs of the nasal ala. The navicular graft offers several advantages: the avoidance of more extensive procedures involving cartilage grafts and/or flaps, appropriate color/texture match, and volume restoration without pitting, notching, or retraction of nasal structures. In addition, no struts or bolsters are needed. Reconstruction of deep nasal ala defects can present a challenge. The often thick, sebaceous skin of the nose provides structural support helping maintain ala shape and nasal patency; loss of this support may result in ala deformity and nasal vestibule collapse. The granulation repair of deep alar defects may result in alar retraction and poor cosmesis, while local flaps may sometimes cross cosmetic subunits and result in trapdoor deformity or alar rim distortion . TraditiWhile traditional teaching endorses defatting FTSGs, several studies have demonstrated that the inclusion of subcutaneous fat may reliably restore contour without significantly affecting graft survival ,4. We inThree patients, aged 63 to 78 years, underwent Mohs micrographic surgery on the nasal ala with deep defects that required closure. FTSGs were harvested from the nasolabial fold in two patients and glabellar skin (from a concurrent repair) in one patient. The grafts were sculpted into a boat-like shape, which filled the depth of the defect and were slightly narrower than the defect diameter Figure . Rather Surgical defects measured 8-12 mm in diameter and 4-7 mm in depth  graft and post-harvest sculpting to maximize aesthetic outcomes while potentially avoiding more extensive procedures. Nasolabial or glabellar skin is ideally used due to its sebaceous nature and adequate thickness, allowing the sculpting necessary to match the defect depth. The navicular graft offers several advantages: the avoidance of more extensive procedures involving cartilage grafts and/or flaps, appropriate color/texture match, and volume restoration without pitting, notching, or retraction of nasal structures. In addition, no struts or bolsters are needed.


Among the morphological processes that characterize the early stages of Drosophila oogenesis, the dynamic of the centrioles deserves particular attention. We re-examined the architecture and the distribution of the centrioles within the germarium and early stages of the vitellarium. We found that most of the germ cell centrioles diverge from the canonical model and display notable variations in size. Moreover, duplication events were frequently observed within the germarium in the absence of DNA replication. Finally, we report the presence of an unusually long centriole that is first detected in the cystoblast and is always associated with the developing oocyte. This centriole is directly inherited after the asymmetric division of the germline stem cells and persists during the process of oocyte selection, thus already representing a marker for oocyte identification at the beginning of its formation and during the ensuing developmental stages. The Drosophila ovary consists of 16–18 ovarioles formed by a chain of egg chambers that mature progressively and move from the anterior to the distal region of the ovariole . OogenesThe differentiation of the oocyte through the germarium can be followed by the accumulation of specific oocyte factors, the dynamic of the synaptonemal complex, the organization of the microtubule (MT) cytoskeleton, and the behaviour of the centrioles. Oocyte-specific proteins firstly accumulate in the cytoplasm of the two pro-oocytes, but from late stage 2a they are concentrated in the differentiating oocyte . The synCentriole clustering in only one cell of the cyst represents an additional and peculiar aspect that characterizes the selected oocyte ,9,12. EaThe mechanism that translocates the centriole from the nurse cells to the oocyte is unclear. Although the MT cytoskeleton seems to be dispensable for centriole accumulation to the oocyte ,9, the jAll of the above markers allowed us to recognize the just-selected oocyte from stage 2a cysts, but they do not permit the identification of the oocyte at earlier stages. In contrast, during the asymmetric division of the GSCs, the cystoblast inherits one third of the spectrosome that gives origin to the fusome, a branched structure that expands during the following mitoses and links all the cells of the same cysts through the ring canals . The fusAlthough the complex dynamics of the centrioles within the germarium were beautifully illustrated several years ago by transmission electron microscopy analysis , some asThe Drosophila stock Oregon R was raised on a standard Drosophila medium in 200 mL plastic containers at 24 °C.Ovaries from adult flies were dissected in phosphate buffered saline (PBS) to isolate the anterior region of the ovarioles including the germarium and the early stages of the vitellarium. Next, the samples were fixed in 2.5% glutaraldehyde in PBS overnight at 4 °C. After rinsing for 20 min in PBS, the ovarioles were post-fixed in 1% osmium tetroxide in PBS for 1 h at 4 °C. The samples were then dehydrated through a graded series of ethanol infiltrated with a mixture of Epon–Araldite resin and polymerized at 60 °C for 48 h. Ultrathin sections were cut with a Reichert ultramicrotome, collected with formvar-coated copper grids, and stained with uranyl acetate and lead citrate. We used single slot grids with oval holes to make possible the observations of the serial sections. TEM preparations were observed with a Tecnai G2 Spirit EM (FEI) equipped with a Morada CCD camera (Olympus).Each Drosophila ovariole consists of an anterior germarium and a posterior vitellarium that contains progressive maturing egg chambers. The germarium can be subdivided morphologically into four distinct regions ,17. RegiIn region 1, the cystoblast underwent four rounds of incomplete mitotic divisions which formed a cyst of 16 interconnected cystocytes in region 2a. The elongated centriole remained in one of the two sister cells after the first division of the cystoblast B,B’ and In region 2b, the two pro-oocytes maintained distinct synaptonemal complexes A and theDuring stage 2 C, when tEach cystocyte in region 2a usually held a pair of orthogonal centrioles consisting of a mother and a shorter daughter A,B. HoweOrthogonal centrioles were occasionally observed within the ring canals E. It is n = 11; n = 7; n = 4), stage 5 (n = 6), and stage 6 (n = 8), we noticed that the number of centrioles within the oocyte cytoplasm increased until stage 4, when we found 22–26 centrioles, and then decreased to 10–13 centrioles during stages 5 and 6.By stage 2, the 15 sibling nurse cells had started the endoreplication cycle to provide the developing oocyte with all the cytoplasmic components needed for its growth, which is completed during stage 14 at the distal end of the ovariole. Serial sections of germ cell cysts during stages 2 n = 11; C and 3 (n = 93) and 58% of the centrioles scored during stages 2–5  consisted of mixed MT triplets and doublets , a core centriolar component , and KlpWe noticed during our ultrastructural analysis that distinct procentrioles are not restricted to the dividing stem cells and cystocytes but are also present in regions 2a and 2b when the 16 germ cells stop dividing. These observations confirm and extend previous reports ,14 showiThe presence of odd centriole numbers within the same cells in region 2a, before the process of centriole migration, suggests that the duplication of the parent centrioles is an asynchronous process that overrides the usual cell-cycle controls. The possibility that centrioles replicate in region 2a and maintain their close association until stages 3 and 4 is hard to believe. This observation points to a later duplication process, presumably within the vitellarium. Accordingly, the variable length of the centrioles during these stages could be the result of replication events occurring at different times.No structural differences between the post-mitotic centrioles of the female germ cells have been reported until now. Most of the germ cell centrioles found within the germarium and the early stages of the vitellarium display a slight variation in length and an incomplete tubular wall, often consisting of mixed MT doublets and triplets. Therefore, these centrioles cannot reach maturity with a complete set of triplet MTs. They can duplicate, however, suggesting that, at least in the Drosophila germarium, centriole replication does not require triplets. Functionally active somatic and early embryonic centrioles consist of nine doublets . TherefoAlthough, the centrioles appear to be useless organelles during oogenesis, they must be eliminated because their retention is deleterious for embryonic development. Thus, the mature oocyte lacks centrosomes . Centrio


Adult-to-adult living donor liver transplantation with small partial liver grafts often requires intraoperative portal inflow modulation to prevent portal hyperperfusion and subsequent small-for-size syndrome (SFSS). However, there are concerns about the specific morbidity of these modulation techniques. This study aims to lower post-perfusion portal venous pressure and correct severe hypersplenism in a patient with end-stage liver cirrhosis by simultaneous subtotal splenectomy during auxiliary partial orthotopic liver transplantation (APOLT). A 29-year-old man was diagnosed with cryptogenic cirrhosis and severe portal hypertension suffered recurrent acute variceal bleeding, severe thrombocytopenia, and massive ascites before admission to our hospital. After the recipient's left liver was resected, we performed APOLT using his 51-year-old father's left lobe graft with a graft-to-recipient weight ratio of 0.55%. Intraoperatively, simultaneous subtotal splenectomy was performed to lower graft post-perfusion portal vein pressure below 15 mmHg and correct severe hypersplenism-related pancytopenia. The recipient's postoperative hospital course was uneventful with no occurrence of SFSS and procedure-related complications. Platelet and leukocyte counts remained in the normal ranges postoperatively. The living donor was discharged 6 days after the operation and recovered well-with no complications. After a follow-up period of 35.3 months, both the recipient and donor live with good liver function and overall condition. This is the first case report of simultaneous subtotal splenectomy during APOLT using small-for-size living-donated left liver lobes, which is demonstrated to be a viable procedure for modulating portal inflow and correcting severe hypersplenism in selected adult patients with end-stage liver cirrhosis. APOLT using a small-for-size liver graft may be a safe and feasible treatment option for selected adult patients with end-stage liver cirrhosis. Due to a critical shortage of donor organs, living donor liver transplantation (LDLT) has been increasingly used in adult recipients. In general, a graft ≥0.8% of the recipient's body weight or 30–40% of standard liver volume (SLV) is necessary to meet the recipient's functional demands, whereas procuring such a graft from a living donor may subject a healthy individual to a significantly high operative risk . To ensuAuxiliary partial orthotopic liver transplantation (APOLT), which is implanting a normal partial liver allograft while preserving part of the native liver, has emerged as an attractive alternative to liver transplantation (LT) for the treatment of selected patients , 4. The Post-transplant portal hyperperfusion is believed to be a primary contributor to the pathophysiology of SFSS. In this setting, intraoperative portal inflow modulation techniques, including splenectomy, splenic artery ligation, and portosystemic shunts, can be used to optimize the post-perfusion portal vein pressure (PVP) and thus prevent SFSS-related graft loss , 14. YosThe present case describes an adult patient diagnosed with cryptogenic cirrhosis and severe portal hypertension who underwent APOLT using a small volume living-donated left liver lobe. Simultaneous subtotal splenectomy was performed intraoperatively to lower graft PVP and correct severe hypersplenism-related pancytopenia.3 and white blood cell count 600/mm3). Serum biochemical examinations showed slightly elevated total bilirubin (2.0 mg/dl) and conjugated bilirubin (0.57 mg/dl), normal aspartate aminotransferase (26.6 IU/l) and alanine aminotransferase (6 IU/l), normal serum creatinine (67 μmol/l) and electrolytes  and low albumin level (2.91 g/dl). The blood ammonia level was 33 μmol/l, and the patient did not experience any episodes of hepatic encephalopathy previously. His international normalized ratio (INR) was slightly prolonged (1.49). Abdominal computed tomography (CT) showed atrophic liver, severely dilated gastroesophageal varices and short gastric veins, umbilical vein recanalization, splenomegaly, massive volume of free peritoneal fluid, and small volume of bilateral pleural effusion. The Child–Pugh classification was B (score 9), and the Model for End-Stage Liver Disease (MELD) score was 12. After a discussion between the patient and his parents and the multidisciplinary team, including radiologists, hepatologists, and liver transplant surgeons, the patient refused to undergo partial splenic embolization, surgical shunt or transjugular intrahepatic portosystemic shunt because the patient thought that abovementioned procedures were just temporary therapeutic options but not a cure, with the potential high risk of procedure-related complications including portal vein thrombosis, substantial infectious risk, and occurrence of hepatic encephalopathy, which may adversely influence his quality of life and the subsequent chance of LT. On the other hand, the indication for LT in this patient was relatively clear, namely decompensated liver cirrhosis, including portal hypertension, recurrent variceal hemorrhage, splenomegaly, hypersplenism, and moderate to severe ascites. In such a situation, considering the patient's own wish regarding the LT and the donor's safety being the priority during LDLT, as well as our transplant team's previous extensive experience with APOLT, and thus APOLT using a small-for-size living-donated left liver lobe was considered for this patient.A 29-year-old man was admitted to our hospital because of recurrent variceal bleeding. One year ago, he presented with sudden melena and was diagnosed with cryptogenic cirrhosis and severe portal hypertension at the local hospital. Since then, he had experienced seven episodes of acute variceal bleeding despite multiple endoscopic therapies  and regular administration of non-selective beta-blockers (carvedilol). Two months ago, he suffered from a hemorrhagic shock caused by gastrointestinal bleeding. On this admission, he had melena and his blood routine examination revealed moderate anemia (hemoglobin 75 g/l) and severe hypersplenism /SLV was 36.71%. Thus, APOLT using a left lobe liver graft was designed to decrease the morbidity of SFSS in the recipient. Given the presence of severe portal hypertension, hypersplenism, and massive splenomegaly, simultaneous subtotal splenectomy was planned, which served as a portal inflow modulation strategy and treatment for severe hypersplenism. The calculated volume of the whole spleen and the designed preserved upper pole of the spleen were 1,445 and 503 ml, respectively .The donor underwent a left hemihepatectomy with preservation of the middle hepatic vein, and the intraoperative course was uncomplicated. The actual graft weight was 405 g, GRWR was 0.55%, and GV/SLV was 31.23%. The recipient underwent APOLT with preservation of the native right lobe liver . Before Based on our and other centers' experience, vaccination against pneumococci and any other encapsulated bacteria was not performed before or after transplantation , 21. To Apart from massive ascites production, the postoperative hospital course was uneventful, and graft function recovered rapidly . It tookWith a critical shortage of donated organs and increased mortality for those on the waiting list, living donors have become an increasingly accepted potential alternative source of organs for adult patients with end-stage liver disease. Due to the assurance of donor's safety being the priority in LDLT, SFSGs have been used to minimize risks to donors in adult-to-adult LDLT. However, SFSGs are generally considered unsafe in terms of the risk of SFSS . NotablyNotably, the functional competition of the portal vein flow between the remnant native liver and the implanted graft is a significant concern of APOLT, leading to progressive growth of one-side conquering liver and chronic atrophy of the defeated liver , 25. In Previous studies have suggested that preoperative graft-to-spleen volume ratio (GSVR) at a ratio of <0.6 g/ml is a good predictor of the development of post-transplant portal hyperperfusion; therefore, it can be used to indicate whether splenectomy is required before reperfusion , 27. YaoMore recently, Zhou and Wei et al. performed simultaneous partial splenectomy during LT in patients with severe hypersplenism, which achieved a satisfactory long-term hematological response but avoided untoward complications of total splenectomy , 33. A rThis case suggests that simultaneous subtotal splenectomy during APOLT using small-for-size living-donated left liver lobes is not only an efficient intraoperative portal inflow modulation strategy but also a feasible treatment for severe hypersplenism in selected adult patients with end-stage liver cirrhosis. It could be a viable alternative to splenectomy, which preserves splenectomy's beneficial effects but avoids splenectomy-related lethal complications. Furthermore, APOLT using a small-for-size liver graft may be a safe and feasible therapeutic option for selected adult patients with end-stage liver cirrhosis, which can further expand the pool of donor grafts.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by the Ethical Committee of Beijing Friendship Hospital, Capital Medical University (No. 2018-P2-127-01). The patients/participants provided their written informed consent to participate in this study and for the publication of this case report.Z-JZ and LW: conception and design of the research, analysis and interpretation of the data, and preformation of the operations. G-PZ: acquisition of data, statistical analysis, and writing of the initial draft of manuscript. WQ, Z-GZ, YL, and L-YS: clinical management and follow-up of the patient. All authors involved in the critical revision of the manuscript for important intellectual content and approved the final version of the manuscript.The present work was supported by the Capital's Funds for Health Improvement and Research (Grant/Award Number: 2020-1-2024) and Beijing Municipal Science and Technology Commission (No. Z211100002921026). The funding body had no role in the design of the study and collection, analysis, and interpretation of data, and in writing the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Determining the geometric characteristics of even complex cross-sections of steel beams is not a major challenge nowadays. The problem arises when openings of various shapes and sizes appear at more or less regular intervals along the length of the beam. Such alternations cause the beam to have different stiffnesses along its length. It has different bending and shear stiffnesses at the opening point and in the full section. In this paper, we present a very convenient and easy-to-implement method of determining the equivalent stiffness of a beam with any cross-section (open or closed) and with any system of holes along its length. The presented method uses the principles of the finite element method (FEM), but does not require any formal analysis, i.e., solving the system of equations. All that is needed is a global stiffness matrix of the representative volumetric element (RVE) of the 3D representation of a beam modeled with shell finite elements. The proposed shell-to-beam homogenization procedure is based on the strain energy equivalence, and allows for precise and quick determination of all equivalent stiffnesses of a beam . The results of the numerical homogenization procedure were compared with the existing analytical solution and experimental results of various sections. It has been shown that the results obtained are comparable with the reference results. Load-bearing members of structures often require regular perforations/holes or uniquely placed openings. This requirement may arise from various causes. One reason is for carrying out installations, such as with electrical wiring or fire sprinkler systems . Going tComputing the properties of the structural member for a constant cross-section is a typical structural/mechanical engineering problem that is easy to solve. However, if a structure member with regular holes or uniquely placed openings is used, the common approach is not sufficient. For the constant cross-section, even with complicated, multi-material assembly, the problem may be solved analytically if an elastic range is considered. The problem is complicated if non-elastic behavior is considered, because in such cases the cross-section properties are not enough to determine the behavior of the structure. In such cases, the General Nonlinear Constitutive Law (GNCL) can be used, as for instance in these works ,7,8,9. OHowever, for detailed geometries, the classical finite element method is not cost effective. As an alternative, the extended approach with simple homogenization technique can offer the benefits of the numerical approach in an engineering practice. Classical FEM is not effective, because the member with regular holes or unique openings would require modelling it via solid or at least shell elements ,2,10. SuHomogenization techniques are used to solve complex mechanical problems in structures for many years. Various approaches have been used, for instance in , for latAmong other scientists who have recently made their contribution to the development of homogenization techniques, one should mention ,16,17,18When applying homogenization techniques, one eliminates the analytical and classical FEM drawbacks, i.e., nonexisting solutions, overcomplex problems or costly solutions. Homogenization techniques enable the modelling of very detailed geometries, for instance with regular holes along the member ,21. It sThe paper’s main objective is to present a novel shell-to-beam numerical homogenization method based on deformation energy equivalence. The derivation and application of a numerical homogenization technique are demonstrated in thin-walled beams with periodic openings. The Materials and Methods chapter consists of two sections. In the first section, the numerical models used are described, while in the second the mathematical details of the homogenization method are explained. The Results chapter contains mainly a comparison with the analytical approach and nominal numerical examples of the homogenization technique. In the first section of this chapter, Z and C profiles without any holes were considered, while in the second section, more elaborate cases were used, i.e., one with the holes in the web and rounding in the corners. In the Discussion chapter, the results obtained are comment upon in detail, and the references to the experimental results from the literature were also investigated. Good agreement of the results with the reference data was obtained in all examples presented.The thin-walled cold-formed profiles of Z, C and square tube are the numerical examples considered in this paper. Thin-walled cold-formed profiles are cost-effective modern building members used in light structures. Apart from economics, their main advantage is quick and effective forming of wall and roof purlins in such facilities as industrial buildings, warehouses, commercial buildings, livestock structures and production halls. However, these kinds of members are vulnerable to initial imperfections and local instability ,31. As aThe numerical examples of the Z, C and square tube profiles considered here may be divided into three categories: (i) no corner-rounding and no holes, (ii) corner-rounding and no holes, and (iii) both corner-rounding and periodic holes. The examples from the (iii) category are presented in In order to build the full stiffness matrix, was used .In entation ). In allIn this work, for computing the reference results used in the verification section see , the typHomogenization is often used for a significant simplification of the computational model, which in turn saves computational time for the given problem. This is especially important in the case of 3D models that contain inclusions, cavities, pores or dispersed reinforcement. Modeling of such structures requires the use of advanced meshing techniques as well as careful and laborious partitioning techniques in order to properly assign the appropriate mechanical features to different parts of the model.x and y axis) and the cross-sectional area as well as material data are sufficient  and the model reduced to a structural element see .In order to compare both models , the first step is to condense the stiffness of the full model to the nodes, in which the kinematic boundary conditions are applied. For this purpose, the global stiffness matrix is subject to static condensation  the strain energy can be expressed by the following formula:z axis, x and y axis), By introducing the strain-displacement transformation matrix, The heart of the method is the transformation matrix Thus, the complete shell-to-beam homogenization procedure consists of the following steps:Build a full stiffness matrix Static condensation of the stiffness matrix to the outer nodes  and an analytical approach for profiles from the (i) category example. The calculations were made for the C and Z profile without holes and no corner-rounding, depending on the elongation depth and mesh seed size. The change in stiffness due to mesh seed for the Z profile belonging to the (i) category example with constant elongation depth of 100 mm is presented in In addition, the normalized stiffness for this case are presented in In the next step, the numerical homogenization was used to compute profiles from examples of the (ii) and (iii) categories i.e., Z profile, C profile and square tube with rounding, were considered. The comparison of stiffnesses obtained from those profiles with hole and without hole is presented in The conducted analyses allowed to obtain information what is the influence of the RVE depth and mesh size on the stiffness of a thin-walled beam for the cross-sections considered. Additionally, the influence of holes on the stiffness was studied. Based on results presented in The analyzes presented in the The homogenization method presented was also verified with the experimental results from the literature, namely, with the study of Nawar et al. . In the The authors are aware of a few limitations of the work. Namely, nonlinear material properties cannot be taken into account, and therefore only the elastic response of the beam can be determined . Moreover, a discretization of the FE model used is crucial to receive trustworthy results of the numerical homogenization technique proposed. In addition, the periodicity of the beam enforces the RVE depth in beam axial direction, which may not allow finding the optimal FE mesh for reliable results.The homogenization method derived can be also used in the different engineering disciplines for example to find optimal cross-sections for particular load-bearing elements. This technique may be used e.g., in computer aided design of optimal purlins or trusses in structural engineering, road crush barriers in civil engineering or light mounting rails in environmental engineering, etc. Using homogenization technique proposed can greatly reduce the computational time which is always crucial in such optimization problems. In academia, the method has the potential to be still developed by adding more peculiar conditions, such as periodic boundary conditions, or including nonlinear effects  and many others. According to the best knowledge of the authors, the homogenization method used  iIn the paper, the shell-to-beam homogenization technique was developed and presented. The homogenization technique proposed has been adapted from the already existing technique based on elastic deformation energy equivalence. The proposed extension of the homogenization method allows to compute effective stiffnesses of the 3D thin-walled beam with periodic openings along its length, which drastically simplifies computations. The main idea utilizes constructing a deformation-displacement relationship which represents an elastic strain energy equivalence of the full 3D model (homogenized) by the simplified model .The effectiveness of the technique proposed was confirmed by three numerical examples of thin-wall cold-formed Z and C profiles, as well as square tube by the comparison of the numerical outcomes of the homogenization with their analytical counterparts. One of the main advantage of the homogenization technique proposed is evidenced in perforated beam sections, which are costly to be modelled via traditional finite element models or too complex to get a solution analytically. In the paper, it was proved by the numerical examples that the technique is adequate to be used in perforated beams with local or regular holes/openings in the thin-wall profiles, but is not limited to such. The technique may be extended to be used in other types of structural members, such as hot rolled sections, wooden elements or encased sections. Future work would be devoted to including imperfections in the homogenization technique with fuzzy probability.


Adipokines are active molecules with pleiotropic effects produced by adipose tissue and involved in obesity-related metabolic and cardiovascular diseases. Arterial stiffness, which is a consequence of arteriosclerosis, has been shown to be an independent predictor of cardiovascular morbidity and mortality. The pathogenesis of arterial stiffness is complex but incompletely understood. Adipokines dysregulation may induce, by various mechanisms, vascular inflammation, endothelial dysfunction, and vascular remodeling, leading to increased arterial stiffness. This article summarizes literature data regarding adipokine-related pathogenetic mechanisms involved in the development of arterial stiffness, particularly in obesity, as well as the results of clinical and epidemiological studies which investigated the relationship between adipokines and arterial stiffness. All these diseases play an essential role in the vascular aging process and contribute to an increase in cardiovascular morbidity and mortality. Obesity, characterized by an increased body mass index (BMI) ≥30 kg/m factors . In addiAdipose tissue is currently classified into three main types: white adipose tissue, which stores energy in the form of triglycerols; brown adipose tissue, involved in thermogenesis; and beige or bright adipose tissue, which contains inducible brown cells and has important thermogenetic roles. White adipose tissue is found in gluteofemoral, subcutaneous and visceral adipose tissue which surrounds various internal organs including the heart.Over the last two decades, a lot of experimental and clinical studies have highlighted the important endocrine, autocrine and paracrine functions of the adipose tissue, particularly white adipose tissue, which produces physiologically active substances called adipokines. Adipose tissue-derived adipokines are involved in various metabolic and immune processes and contribute to maintaining body homeostasis . ObesityWhile visceral and subcutaneous fat produces systemic effects by the release of adipokines and other active molecules, perivascular fat, which is in direct contact with blood vessels, was found to have strong paracrine effects influencing the cardiovascular system independently of general obesity .Arterial stiffness is the result of several important morphological modifications of the arterial wall, including increased collagen deposition, reduction in and fragmentation of elastin fibers, irreversible cross-links between advanced glycation end products and collagen, vascular smooth muscle cells (VSMCs) hypertrophy, and matrix calcification . Aging iMany epidemiological and clinical studies evaluating arterial distensibility in obese subjects have shown that obesity, particularly in its abdominal form, is associated with increased arterial stiffness ,11,12,13The pathogenesis of arterial stiffness in obesity is not completely elucidated. Insulin resistance, systemic inflammation, oxidative stress, renin–angiotensin–aldosterone system (RAAS) activation and increased vascular tone due to the activation of the sympathetic nervous system are some important mechanisms linking obesity to vascular disease. Data from experimental and human studies support the involvement of adipokines in the complex mechanisms that induce obesity-related arterial stiffness ,16.Adipokines are cytokines produced by various types of cells, including adipocytes, macrophages and lymphocytes, particularly in white adipose tissue. According to their relationship with systemic inflammatory response, adipokines have anti-inflammatory or pro-inflammatory effects. The great majority of adipokines are pro-inflammatory, including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), adipocyte fatty acid-binding protein (A-FABP), plasminogen activator inhibitor-1 (PAI-1), resistin, leptin, and monocyte chemoattractant protein-1 (MCP-1). They are related to obesity metabolic and vascular complications. A small number are anti-inflammatory, protective adipokines, such as adiponectin omentin, C1q/TNF-related protein-9 (CTRP9) and apelin. In obesity, the increase in white adipose tissue from visceral deposits shifts the balance in favor of pro-inflammatory molecules , activatThis review summarizes the literature data regarding the adipokine-related pathogenetic mechanisms involved in the development of arterial stiffness, particularly in obesity, as well as the results of clinical and epidemiological studies investigating the relationship between adipokines and arterial stiffness.Adiponectin is mainly expressed in adipose tissue . It is sAt the level of the vascular wall, adiponectin inhibits endothelial nuclear transcription factor NF-kB signaling, suppressing inflammatory cytokine production , reducesThe relationship between adiponectin and arterial stiffness has been evaluated in clinical and epidemiological studies. The correlation with various markers of obesity and with fat mass distribution has also been investigated.2), carotid distensibility decreased and intima–media thickness (IMT) increased when compared to a control group with a BMI of 18.5 to 30.0 kg/m2. Obese subjects had suppressed adiponectin and an increased leptin-associated inflammatory profile expressed by higher C-reactive protein (CRP) and low interleukin 10. Adiponectin positively correlated with carotid distensibility. This association was independent of classical cardiovascular risk factors  and inflammation markers, suggesting that adiponectin may be a valid marker of carotid stiffness in these subjects [In extremely obese subjects , from the Hoorn study. Higher adiponectin was associated with reduced peripheral arterial stiffness at all three arterial sites, particularly in patients without cardiovascular disease and diabetes mellitus. There were no correlations with central arterial stiffness. Trunk fat associated with lower adiponectin levels while leg fat correlated with higher levels, which suggested that these fat depots differ in their adiponectin secretion rate. Nevertheless, the authors found that adiponectin only explained a small part of these associations and suggested that other factors such as insulin, glucose levels, inflammatory markers or other adipokines may influence the association between fat mass distribution and arterial stiffness . MoreoveIn patients with prior cardiovascular disease ,40,41 a High molecular weight (HMV) adiponectin, the most active form of adiponectin, has also been studied in relation to arterial stiffness. In a community-dwelling persons study, age-adjusted heart brachial and heart ankle PWV progressively decreased with increased serum HMW adiponectin. Decreased serum HMW adiponectin levels were significantly and independently associated with increased mean PWV, suggesting a protective vascular effect of HMW adiponectin .In prospective studies, low adiponectin levels at baseline correlated with increased arterial stiffness at follow-up. In 142 healthy non-diabetic postmenopausal women, between 40 and 70 years of age, with carotid IMT more than 1 mm at least in one of the three measured segments , low adiponectin was associated with 3-fold increased risk of carotid IMT progression and a 1.7-fold increased risk of arterial stiffness progression after 1-year follow-up. This association was not influenced by traditional cardiovascular risk factors. Adiponectin correlated with CRP but not with intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), suggesting that adiponectin vascular effects may not be explained by adhesion molecules . AnotherThe results of these studies suggested that low adiponectin levels may be not only a marker of vascular disease but also a mediator. However, adiponectin may have different effects depending on the studied population.Omentin-1 is mainly secreted by stromal vascular cells of human visceral fat. Obesity is accompanied by low levels of omentin . It has In a study which included type 2 diabetic patients, omentin-1 was decreased compared to normal glycemic patients and correlated with brachial ankle PWV and carotid plaques after multiple adjustments for cardiovascular risk factors and for medication history . A prospThe CTRP family comprises 15 members which are considered adiponectin paralogs as they share structural similarities with adiponectin. Among all of these, CTRP9 presents the greatest amino acid structural similarities with adiponectin . ExperimIn human studies, CTRP9 has been associated with good glycemic control and an absence of metabolic syndrome . Its valApelin is produced in many tissues, including fat tissue, brain, heart, lungs and kidneys. It has favorable metabolic effects reducing insulin resistance with possible anti-obesity and anti-diabetic properties . Apelin Leptin is mainly produced by the differentiated adipocytes of the white subcutaneous adipose tissue. Leptin has an important role in regulating food intake and energy expenditure in the central nervous system. It reduces appetite and increases energy expenditure. Nevertheless, in obesity, increased fat mass is accompanied by hyperleptimenia, suggesting a state of leptin resistance .The vascular effects of leptin are mediated via specific vascular receptors located in endothelial cells and in VSMCs . The dirHowever, leptin may have opposing vascular and metabolic actions. Experimental studies have shown that leptin favors endothelium-dependent NO-mediated vasorelaxation, corrects impaired antioxidant defense in ob/ob mice and protects macrophages from cholesterol overload. Leptin has been shown to have anti-insulin-resistant properties ,69. In cObesity-induced hyperleptinemia is involved in vascular inflammation. It stimulates the expression of inflammatory cytokines, such as TNF-α, interleukine-2, and IL-6 by monocytes  and lympLeptin has been studied in relation to arterial stiffness, alone or concomitantly with other adipokines in clinical and epidemiological studies.In 294 healthy adolescents, leptin positively correlated with carotid–femoral PWV, independently of body fat mass, blood pressure and CRP. It has been suggested that the vascular effects of leptin may begin early in life, even in non-obese but slightly overweight young subjects, and subsequently, the prolonged action of leptin on the vasculature may increase the risk of adult cardiovascular disease onset . This stA cross-sectional analysis from the Baltimore Longitudinal Study of Aging which included 749 patients (mean age 67 years) investigated adiponectin, leptin and resistin in relation with carotid–femoral PWV and abdominal obesity. This study indicated that increased leptin and resistin and low adiponectin independently correlated with increased arterial stiffness, however, the relationship between each adipokine and stiffness measure was not influenced by the magnitude of abdominal adiposity, suggesting that factors other than obesity may influence the relationship between adipokines and arterial stiffness. Among the three studied adipokines, only leptin explained, in part, the relationship between abdominal obesity and arterial stiffness, because the inclusion of leptin in the statistical model attenuated the relationship between obesity and vascular stiffness .In healthy elderly men, leptin correlated with arterial stiffness and the association of increased leptin with low adiponectin levels had a synergistic effect on the development of subclinical vascular damage indicated by increased carotid–femoral PWV (>10 m/s) . The proIn a large population from the SardiNIA Study, the correlation between metabolic syndrome, aortic stiffness, and carotid IMT and a panel of adipokines including adiponectin, leptin, IL-6, and MCP-1 was investigated. Higher leptin levels were positively associated with increased aortic PWV, while low adiponectin was correlated with increased carotid intima–media thickness, after adjusting for age, sex and other classical cardiovascular risk factors. The association of increased inflammatory cytokines with metabolic syndrome showed to have a synergistic effect on arterial stiffness and thickness . This stIncreased leptin positively correlated with systolic blood pressure and pulse pressure and negatively with arterial compliance in obese/overweight hypertensive, compared to obese/overweight normotensive African women independently of obesity, insulin resistance, and age . These rPositive correlations between leptin and increased carotid–femoral PWV have also been reported in patients with hypertension , coronarHowever, in patients with non-alcoholic fatty liver disease, the leptin/adiponectin ratio did not correlate with brachial–ankle PWV, suggesting that other factors may contribute to vascular alterations in these patients . MoreoveThe name “resistin” was established based on its action of increasing insulin resistance. In animal models, increased levels of resistin induced hyperglycemia associated with elevated hepatic glucose production while the reduction in resistin prevents obesity-related hyperglycemia due to increased insulin sensitivity . In humaIn human adipose tissue, resistin is mainly produced by mononuclear cells  and is iPositive correlations between resistin and arterial stiffness have been reported. In a population study which included 683 randomly selected subjects of African ancestry from Soweto, South Africa, who had never taken antihypertensive therapy, resistin positively correlated with aortic PWV independently of age, blood pressure, and systemic inflammation . Higher All RAAS components can be produced by the adipose tissue, particularly by visceral and perivascular adipose tissue. Angiotensinogen is the precursor of RAAS. Renin cleaves angiotensinogen to produce angiotensin I which, subsequently, is transformed by angiotensin converting enzyme into angiotensin II. Chronic exposure to increased aldosterone, caused by adipocyte production in obesity, induces vascular remodeling and fibrosis as well as endothelial dysfunction. In addition, vascular mineralocorticoid receptor activation in obesity contributes to impaired vascular relaxation and oxidative stress . IncreasWeight loss, one month after bariatric surgery, in patients with severe obesity, significantly improved arterial stiffness. Changes in some components of RAAS were independent correlates for the final values of vascular parameters, suggesting the involvement of this system in obesity-associated arterial stiffness .Favorable effects of the RAAS blockade on arterial stiffness have been reported in obese hypertensive patients. Blocking RAAS with angiotensin converting enzyme inhibitors or angiotensin receptor blockers showed to be effective in reducing arterial stiffness and vascular remodeling in hypertensive patients .PAI-1 is an essential inhibitor of tissue plasminogen activator. Increased PAI-1 activity is associated with reduced fibrinolytic activity and thus with increased cardiovascular risk. Adipose tissue, particularly visceral fat, is an important source of PAI-1. In addition to its role in controlling fibrinolysis, PAI-1 is also involved in vascular remodeling. PAI-1 may modulate neointima formation, VSMCs proliferation and migration, and TGF-β1 activation . Both PAIn human studies, PAI-1 was associated with insulin resistance, metabolic syndrome, and atherosclerosis ,117. In Visfatin (as its name suggests) is an adipokine mainly secreted by the visceral adipose fat. It has also been found in great quantities in the perivascular adipose tissue. Visfatin is also known as pre-B cell colony enhancing factor because it acts as a growth factor for early state B cells. In humans, the principal source of visfatin is represented by macrophages from the adipose tissue, which are stimulated by inflammatory signals . VisfatiIn humans, visfatin, expressed by periaortic and pericoronary adipose tissue, is strongly correlated with atherosclerosis  and withRBP-4 is an adipokine mainly produced by the liver and visceral fat . It incrSeveral mechanisms can explain the RBP-4 involvement in vascular pathology. RBP-4 may increase oxidative stress and stimulate vascular endothelium inflammation leading to endothelial dysfunction. Moreover, RBP-4 induces the macrophage secretion of inflammatory cytokines, including TNF-α, IL-6, IL-2, and MCP-1. It has been associated with a non-favorable lipid profile  which maRBP-4 has been positively correlated with arterial stiffness measured as carotid–femoral PWV in healthy postmenopausal women  and in aA-FABP is mainly produced by the adipose tissue and macrophages from the subcutaneous fat. It is involved in inflammatory and metabolic processes. Increased levels of A-FABP have been correlated with insulin resistance, vascular inflammation, endothelial dysfunction, and the development of atherosclerosis .In clinical studies, A-FABP has been positively associated with obesity and metabolic syndrome . ArteriaChemerin, an adipokine secreted by the white adipose tissue, is significantly higher in obese individuals . Weight In clinical studies, a direct correlation between chemerin and various markers of arterial stiffness has been reported. In 120 healthy subjects, chemerin correlated with brachial–ankle PWV independently of classical cardiovascular risk factor, homeostasis model of insulin resistance, and high-sensitivity CRP . An indeLocal perivascular and epicardial chemerin expression may play a role in vascular pathology. Increased secretion of chemerin in perivascular and epicardial tissue has been associated with aortic and coronary atherosclerosis. Moreover, hypertensive subjects had increased chemerin secretion in periaortic adipose tissue and aortic VSMCs compared to normotensives, suggesting a possible role of the perivascular fat secretion of chemerin in blood pressure control ,155.Nevertheless, in patients with chronic kidney disease, chemerin was associated with low coronary calcium score despite positive correlation with renal function, cardiometabolic risk factors and inflammation. Chemerin was also correlated with two calcification inhibitors, fetuin-A and matrix Gla protein. In murine VSMCs, chemerin increased matrix Gla protein and reduced calcification. In contrast with previously mentioned studies, chemerin did not correlate with the augmentation index, a marker of arterial stiffness, which depends on vascular calcification as well as on vascular fibrosis and endothelial function . All theTNF-α and IL-6 are two cytokines involved in systemic inflammatory syndrome.TNF-α is mainly secreted by macrophages which infiltrate adipose tissue, while its adipocyte synthesis is reduced . In obesIL-6 is produced by adipocytes, endothelial cells, VSMCs, and macrophages ,158. In The vascular effects of IL-6 are mediated by multiple mechanisms. Depending on the signaling pathway activated—classic or trans-signaling—Il-6 can produce different effects. IL-6 exerts its action by binding to its surface receptors, IL-6R. Soluble forms of IL-6R combined to IL-6 can induce glycoprotein 130 (gp130) dimerization in cells that do not express IL-6R, rendering them responsive to IL-6 through a process called trans-signaling . In endoObesity and metabolic syndrome are accompanied by persistently increased IL-6 and TNF-α levels which may contribute to insulin resistance and deleterious vascular effects ,162. TNFIn patients with acute ischemic stroke and metabolic syndrome, measures of arterial stiffness  and inflammatory cytokines (TNF-α and IL-6), along with CRP, were increased compared to patients with acute ischemic stroke without metabolic syndrome. TNF-α, IL-6, and CPR more strongly correlated with arterial stiffness parameters in patients with ischemic stroke and metabolic syndrome compared to those with acute ischemic stroke but without metabolic syndrome . IncreasSoluble TNF-α receptors—sTNFR1 and sTNFR2—were positively associated with brachial–ankle PWV in patients with coronary artery disease undergoing invasive coronary angiography, independently of blood pressure and aging . A positThe implication of TNF-α in vascular stiffness is also supported by the fact that anti-TNF-α agents used to treat inflammatory arthritis patients with increased arterial stiffness had favorable effects on stiffness parameters .IL-6 correlated with carotid distensibility in uncomplicated type 2 diabetes mellitus, mediating the relation between abdominal fat and carotid distensibility . IL-6 coIn healthy women, the soluble receptor of IL-6 but not IL-6, inversely correlated with flow-mediated dilation. Like TNF-α receptors, soluble IL-6 receptors seem to be better indicators of early vascular changes than the interleukin itself . MoreoveThe IL-6–174-G/C promoter polymorphism, previously associated with inflammation, has been investigated in relation to arterial stiffness in a large population-based sample from the Rotterdam study. The results indicated a significant correlation between the C-allele of the polymorphism and increased carotid–femoral PWV. A tendency, even though statistically insignificant, of association between IL-6 and increased PWV, was also reported, but the number of IL-6 samples was small .SAA is an acute phase protein produced by the liver, but it can also be synthesized by other cells including macrophages and adipocytes . Its hepSAA is increased in obesity and metabolic syndrome  and it cSAA has also been studied in relation to preclinical vascular disease. Increased SAA levels were positively correlated with CAVI in Japanese adults, which were non-medicated and free of cardiovascular disease , as wellMCP-1 is a chemokine produced by various cells, particularly monocytes/macrophages and endothelial cells, and has an important role in local inflammation. MCP-1 binds on its receptor chemokine (C-C motif) ligand 2 (CCL2), expressed in monocytes, and attracts them to the site of inflammation. Once recruited, monocytes enhance inflammation through the secretion of inflammatory cytokines such as IL-6 and TNF-α in endothelial cells ,191. MCPMCP-1 expression is mainly localized to the thickened intima and it promotes VSMCs proliferation and migration, contributing to vascular remodeling . MCP-1 iAll these mechanisms indicate that MCP-1 is involved in vascular inflammation and remodeling which may induce arterial stiffness. However, the results of clinical studies are conflicting. In a large sample of young healthy subjects, from the African-PREDICT Study, MCP-1 did not correlate with arterial stiffness. Its values were higher in young black Africans compared to white subjects, and positively associated with carotid IMT in black women, suggesting that MCP-1 may contribute to early development of vascular alteration in this population, which is known to be at increased cardiovascular risk . In chilPerivascular adipose tissue is the adipose fat which surrounds large arteries (aorta), medium-size (mesenteric arteries) and small arteries (resistance arteries). Epicardial fat plays the role of the perivascular adipose tissue for coronary arteries. In lean subjects, perivascular adipose tissue is a source of adipokines with favorable effects. Among them, the most important is adiponectin which has vasodilatory effects on small arteries, stimulates local endothelial NO synthesis, reduces inflammation-suppressing adipocytes’ secretion of CRP, IL-6, and TNF-α, inhibits VSMC proliferation, and prevents monocyte adhesion to aortic endothelial cells . In obesAdipokines are active molecules synthetized by the adipose tissue, with various metabolic and vascular functions. Obesity, characterized by persistent low-grade inflammation, is accompanied by a disturbed balance of secretion of proinflammatory/inflammatory adipokines secretion. Increased proinflammatory adipokines are important mediators of obesity-associated pathologies, including cardiovascular diseases. Various mechanisms can explain the implication of adipokines in arterial stiffness through the activation of vascular inflammation and oxidative stress, the stimulation of vascular fibrosis and calcification, and the precise roles of adipokines are not yet clarified. From a clinical viewpoint, the use of different measures of arterial stiffness and the various pathologies associated in obese patients, make difficult the comparison between studies.In addition to circulating adipokines, recent research has highlighted the role of perivascular adipose tissue adipokines, in the development of arterial stiffness in obesity. Nevertheless, the confirmation of a cause–effect relationship between adipokines and vascular stiffness needs futures prospective large studies.