Self-expanding frames for minimally invasive implants are typically made from nitinol wires and are heat treated to maintain the desired shapes. In the process of heat treatment, nitinol structures are placed in a high-temperature oven, while they are confined by a fixture. During this process, nitinol exerts a high amount of force. Accordingly, a fixture requires high mechanical strength and temperature resistance; this is why fixtures are typically made from metals. The use of metal fixture also increases the turnaround time and cost. However, accelerating this process is beneficial in many applications, such as rapid development of medical implants that are patient-specific. Inspired by the use of sacrificial layers in microfabrication technology, here we propose a novel method for shape setting nitinol wires using a sacrificial metal fixture. In this process, the nitinol wires are first aligned inside copper hypotubes. Next, the forming process is done using hand-held tools to shape complex geometrical structures, annealing the nitinol reinforced by copper, and then selectively etching copper hypotubes in ammonium persulfate solutions. In this process, other sacrificial cores, which are 3D printed or cast from low-cost polymers, are also used. This combination of polymeric cores and minimal use of metals enables reducing the cost and the turnaround time. As a proof of concept, we showed that this process was capable of fabricating springs with mm or sub-mm diameters. The result showed a change of less than 5% in the intended diameter of the nitinol spring with diameters ranging from ~ 0.7 to 1.9 mm, which confirms copper as a suitable sacrificial fixture to obtain the desired complex geometry for nitinol. A metric, based on the elastic strain stored in copper is suggested to predict the possible variation of the intended dimensions in this process. Finally, to demonstrate the potential of this method, as proof of concept, we fabricated NiTi wire frames designed for anchoring through the atrial septum. These frames demonstrated septal defect occluders that were designed based on a patient’s cardiac image available in the public domain. This low-cost rapid fabrication technique is highly beneficial for a variety of applications in engineering and medicine with specific applications in rapid prototyping of medical implants. In the process of shape setting, nitinol structures are traditionally placed in an oven at ~ 500 °C5, while they are confined by a fixture3. During this process, nitinol undergoes a high amount of stress, which requires a fixture with high mechanical strength at the specified high temperature. This is why fixtures are typically made from metals4. However, this need poses both a challenge and high cost for rapid prototyping and testing of nitinol structures due to the requirement for fabricating metal fixtures. Direct 3D printing or machining metal fixtures are expensive processes. Alternatively, the use of a reconfigurable fixture, made from pins and plates6, simplifies the process of fabricating fixtures, however, it has limited capability in forming complex geometries. More recently, ceramic8 and wooden9 fixtures with local Joule’s heating effect were introduced; however, they still have limitations on forming more complex geometries. Therefore, cost-effective annealing of nitinol are still under investigation11.Shape setting nitinol (NiTi) wires14 especially the lift-off process15, however, in this context the layers are used as a spacer rather than load-bearing structures. This process involves choosing a sacrificial layer on which the main material will be deposited. Subsequently, the sacrificial material and etchants/solvent16, are chosen such that the sacrificial material can be selectively etched/dissolved without damaging the main structure. Copper (Cu) as a sacrificial material, in the lift-off process, has been used for fabrication of nitinol microelectromechanical systems (MEMS)17, and micropatterned thin films19. The latter two reports19 investigated the use of Cu as a sacrificial layer for fabrication of thin and thick film patterned NiTi. Such patterned NiTi films were also suggested19 to be used as an additional layer in covering stents. Another example of this lift-off process is fabrication of thin film NiTi thermostat arrays deposited on sacrificial Cu and chromium (Cr) layers20. Despite these reports on the utility of Cu as sacrificial material in deposition of free standing NiTi films, the use of Cu as sacrificial fixtures for annealing NiTi has been less explored, in the literature, to our best knowledge. This use of Cu as a sacrificial layer in the lift-off process suggests the possibility of its use as a sacrificial fixture (load-bearing components) for the shape setting, which is the focus of this work.Use of sacrificial layers or structures is a concept that is widely used in microfabrication21, left atrial appendage occluders (WATCHMAN™)22, stone extractors (NCircle®)23, stent grafts24, and transcatheter aortic valves25. In addition, recently there has been an interest in methodologies for designing and fabricating patient-specific implants27, rather than conventional universal implants. A unique capability for this paradigm is the use of a patient’s medical imaging data for the design and fabrication of patient-specific implants. While this engineering approach is under investigations, the capability of this paradigm can be improved by development of processes that allow for rapid iterations of designing, fabricating, and testing an implant within a timeframe of few days. Although, several investigations have shown the feasibility of this paradigm for polymeric implants28, from an engineering perspective, limited success has been shown for nitinol implants. This need for exploring NiTi implants also motivates the current work to introduce a fabrication process to be employed for the rapid prototyping of transcatheter implants that leverage nitinol frames.The advantages of a reliable and cost-effective process for rapidly iterating nitinol frames  are significant for the research and development of minimally invasive implants and devices. Many implants or medical devices rely on self-expanding frames that are fabricated from various forms of wires, sheets, tubes, etc. Few examples include, implantable sensors (CardioMEMS™)16. We chose copper because (1) it enables large plastic deformation at room temperature29 (2) its melting temperature is well above nitinol’s annealing temperature, and (3) miniaturized hypotubes are commercially available. Although we were unable to find reports on the selective (NiTi) etch rate of nitinol in ammonium persulfate, it could be inferred from other work that nickel16 had insignificant etch rates in commercial solutions of ammonium persulfate (APS 100). In this work, we assess whether the nitinol structures with various shapes could be released completely. We also assess, if any detrimental surface chemistry or significant change in diameter is observed after releasing the structures.Here we propose adapting the concept from the lift-off process in microfabrication  for shape setting nitinol structures with a small form-factor. In this process, the ideal sacrificial fixture must be: (1) low cost, (2) easily deformable at room temperature, (3) able to tolerate stresses during the annealing process and, (4) could be etched selectively without damaging the annealed nitinol. In this work, we assess this possibility by shaping nitinol into typical shapes such as springs. We also assess the possibility to shape set nitinol with complex shapes with small and large form factors. We hypothesize that copper hypotubes, as the sacrificial layer, and ammonium persulfate as etchant, could be employed, given prior use of this chemical for selective etching of sacrificial copper31) are also envisioned. Implantable NiTi frames are typically processed starting with NiTi tubes , plates , and wires . A review on self-expanding NiTi stents made from wires, sheets and tubes can be found elsewhere2. Although the use of NiTi tubes is the more common form in fabricating self-expanding implants/frames, other forms such as wire  or rolled patterned sheets2 have been also employed in commercial implants or research on NiTi stents. However, in this study, we limit the focus of this work to wire/frames with a small form factor. The success of this method can introduce new routes for development of the implants that require nitinol wire frames. Few examples are crimped NiTi frames33 used in heart valves, nitinol wire/frames in septal defect occluders35 or NiTi wire/frames in graft stents36 that are formed by cylinder and pin fixtures. The direct application of this technique is in any processes that involved shape setting NiTi wires, that are commonly done using fixtures and/or pins, and crimping/welding them into self-expanding framse34.Here, this work demonstrates the novel technique of copper reinforcement for the heat treatment of nitinol. This effort focuses on the processes that have applications in the rapid prototyping of self-expanding nitinol frames. Such frames have applications in the fabrication of medical implants, however, other applications in the aerospace industry  is beyond the scope of this work. Nonetheless, we note that the usage of copper as a sacrificial fixture, in principle, could be integrated with any of the aforementioned annealing or surface treatments that can be studied in the future.While annealing NiTi in airTo assess whether NiTi is etched in ammonium persulfate solutions, we characterized a straight NiTi wire (0.003″ diameter) before and after the proposed processes using both an optical microscope and a micrometer. To estimate the lower bound of the elastic strain limits of the NiTi wires (0.003″ diameter), four wires were wrapped around cylinders and then released. At each step, we optically characterized whether they could recover their straight form after release. Gradually, the bending radius is reduced until the wire can no longer fully return to its initial form. Subsequently using beam theories, the corresponding elastic strain limit is estimated.37 and segmented out the atrial septum using the open-source Slicer 3D38  which is flexible but firmer than the silicone . To accomplish this, we first 3D printed an atrial septum, which served as the foundation for the septum fabrication  was performed on a NiTi wire (~ 0.003″) that was untreated and one . Additionally, by subjecting the 0.003" diameter NiTi wire to heat treatment and etching processes, we confirmed a full recovery of at least 2% strain through simple bending of the wires over cylinders.The tight variation of dimensions in the spring suggests the application of hypotubes for the fabrication of patient-specific self-expanding frames. To demonstrate this concept, the inter-atrial septum was segmented out from a de-identified individual’s CT images. Subsequently, silicone/PVA sacrificial cores with the shape of the septum are fabricated. Figure The proposed approach demonstrated its capability for fabricating frames (0.006″ diameter wires) with irregular shapes, such as triangles Fig. f or cyliEDS signals for NiTi wires (untreated and processed) are depicted in Fig. One can utilize sacrificial cores to facilitate the fabrication of complex topologies that are difficult to achieve using a traditional metal fixture. For example, a combination of sacrificial polymeric cores and metal pins/screws . Finally, we envision that Cu/NiTi can be integrated with other additive manufacturing techniques that process continuous fibers such as automated fiber placement54 or continuous fiber 3D printers55 for the fabrication of complex topologies of NiTi/Cu topologies. This technology, if integrated with automated crimping tools, can offer exciting opportunities for the rapid prototyping of complex NiTi structures.The introduced process offers improvements in rapid prototyping of NiTi structures that leverage additive manufacturing, and digital manufacturing. First, it enables the use of low-cost 3D-printed polymers as the cores or fixtures for shape setting nitinol. Although direct 3D printing NiTi58. Specifically, the effects of processes such as etching on the long-term durability and biocompatibility of the frames should be investigated. Further studies on the surface chemistry and biocompatibility of NiTi frames may also reveal the need for additional processes such as etching NiTi or the use of vacuum ovens or salt baths. Another important process parameter to study is the nitinol pre-strain, which is known to impact its fatigue life. Exploring the integration of the proposed technique into computerized wire bending machines or continuous fiber 3D printers could demonstrate novel methods for rapid prototyping of NiTi. Considering that many implants' frames are fabricated in the form of sheets and tubes, introducing composite NiTi sheets and tubes reinforced with copper may significantly expand the utility of the proposed technique in the future. Such reinforcement can be achieved by aligning NiTi sheets/tubes, that are patterned by laser cutters, between two Cu tubes/sheets. Subsequently the outer and inner Cu layers can be spot welded through perforated NiTi areas. This process can produce composite layers of Cu/NiTi/Cu, in the forms of sheets or tubes. Subsequently such structures can be formed by cold forging or cold bending processes. Future work is also envisioned to integrate rapid prototyping of NiTi with other hemocompatible materials (such as Dacron or ePTFE) to facilitate the fabrication of personalized implants.Future work is envisioned to explore the limits of the proposed fabrication method and its potential. Use of NiTi in medical implants requires significant preclinical studies that are envisioned to be addressed in the futureIn summary, we proposed a technique for fabrication of complex NiTi frames from nitinol wires reinforced by sacrificial tubes or hypotubes that were made from copper. In this fashion, upon the bending of nitinol wires, the sacrificial tube deforms (with plastic deformation) at room temperature and creates a permanent supporting fixture. We showed that the sacrificial cores could be removed and the copper hypotubes can serve as a fixture for the heat treatment of nitinol. We demonstrated that miniaturized springs can be fabricated using this method. It was demonstrated that this technique is capable of the rapid prototyping self-expanding frames with possible applications in medical technologies. For a demonstration of the concept, we fabricated NiTi frames with a topology for anchoring on a atrial septum. We further showed that those frames could be customized with the shape of the septum or irregularly shaped plugs. We propose a metric to estimate the control over the dimensions and show that this technique is ideal for the rapid prototyping of NiTi frames with smaller radii of curvature. The capability of this technique in producing complex topologies suggests that this technique have the potential to be integrated with computerized wire forming techniques. These results have significant applications in the rapid manufacturing of nitinol structures applicable in various areas, such as patient-specific or individualized implants.


Background:International Classification of Diseases, Tenth Edition (ICD-10) data help track outpatient antibiotic prescribing but lack validation in immunocompromised populations or subspecialty clinics for this purpose. Asymptomatic bacteriuria (ASB) and urinary tract infection (UTI) are important stewardship targets in renal transplant (RT) patients, but they may require alternative metrics to best monitor prescribing patterns. We describe ICD-10 utilization for RT clinic encounters in which antibiotics were prescribed. We developed a metric classifying “acute urinary antibiotics” (AUA) to track antibiotic use for ASB and UTI, and we validated systematic identification of AUA to enable practical implementation. Methods: We examined RT clinic visit and telemedicine encounters from 2018 to 2021 conducted 1 month after transplant. This project was deemed non–human-subjects research by the Stanford Panel on Human Subjects in Medical Research. Results: The analytic cohort included 420 antibacterial prescriptions from 408 encounters . Of 238 patients, 136 (57%) were male and 112 (47%) were Hispanic or Latino. The most common primary ICD-10 code was Z94.0 (kidney transplant status) ; 26 encounters (6%) were coded for UTI ; and 214 encounters (53%) had multiple ICD-10 codes. The R82.71 code (bacteriuria) was never used. However, 215 prescriptions (51%) were classified as AUA . The validation cohort included 130 prescriptions; 59 (45%) were classified as AUA and 51 (39%) had documented intent to treat ASB or UTI  (Table 1). For patients >1 month after transplant, the positive percent agreement was 95% and the negative percent agreement was 98%. Of 51 patients receiving AUA, 32 (63%) were asymptomatic despite frequently having a code for UTI . Conclusions: ICD-10 coding may not be helpful in monitoring antibiotic prescribing in RT patients. The AUA metric offers a practical alternative to track antibiotic prescribing for urinary syndromes and reliably correlates with physician intent. Monitoring AUA prescribing rates could help identify opportunities to optimize antibiotic use in this complex outpatient setting.Disclosures: None


Immunoglobin-G4 related disease (IgG4-RD) is an auto-immune inflammatory condition where patients present with a tumour-like mass that shows infiltration by plasma cell and subsequent fibrosis. It is a systemic condition that primarily involves the salivary glands, pancreas, kidneys, aorta, and retroperitoneum amongst other organs. Testicular involvement is a rare occurrence in this disease entity. A 55-year old male patient presented with the complaints of pain and swelling in the right scrotal region. Right-sided orchidectomy was carried out which on histopathology showed features suggestive of IgG4-RD which was later confirmed on immunohistochemistry. Whole body MRI revealed that no other organ was involved in the disease process in this patient. IgG4-RD has a variable clinical course and considerable overlap with its differentials. Imaging studies and serum IgG4 levels are neither confirmatory nor customarily diagnostic in every case. The only confirmatory diagnostic investigation is histopathological examination, which shows infiltration of IgG4+ plasma cells and fibrosis in the involved tissue. Whenever a mass-forming lesion with typical histomorphological features is encountered with involvement of multiple organs/anatomic sites, IgG4-related disease should be considered among the differentials, and clinicians of all disciplines should be familiar with this disease entity. IgG4-related disease (IgG4-RD) is a systemic, autoimmune, inflammatory condition, characterised by fibrosis of the affected organ and its infiltration by IgG4+ plasma cells, forming a tumour-like mass . It primA 55-year old diabetic male presented with complaints of pain and swelling in the right scrotal region along with fever for five days. Ultrasound of the scrotum revealed fine internal septae and free fluid in the right scrotal sac along with features of right-sided epididymitis and funiculitis. The testes on both sides were apparently normal on ultrasound . ConsequOn gross examination, the specimen measured 5x4x3 cm. It consisted of the pulp of testes and epididymis, which on cut section showed a central tan-coloured necrotic area and peripheral whitish/fibrotic area . MicroscThereafter a comprehensive whole body work-up including whole body MRI was performed to determine the involvement of other organs but no systemic involvement could be ascertained. Furthermore, his liver, kidney and thyroid function tests as well as lipid profile and serum amylase and lipase were found to be within the normal range. Hence, it was concluded that this was a case of IgG4-related disease where the solitary site of involvement was the right testicle. The patient is doing well on follow up.IgG4-RD can present with lesions in a variety of anatomic sites, either synchronously or metachronously, but is shown to have similar histomorphology which is characteristic of the disease ,5,6.The etiology of IgG4-RD is unclear. Non-HLA genes like cytotoxic T-lymphocyte antigen-4 (CTLA-4) and tumour necrosis factor-α have also been implicated. T-follicular helper cells along with T-follicular regulatory cells help in B cell differentiation and class switching, resulting in proliferation of IgG4-secreting plasmablasts and long-lived plasma cells. CD4-positive T cells are central to the disease. Their clonally expanded population is seen in both peripheral blood and fibrotic lesions and shows active involvement in development of fibrosis. The T helper type 2 (Th2) pathway, which is responsible for eosinophilic infiltration by IL-5 release, is no longer considered central to disease pathogenesis ,5,7.The two consistent clinical findings are tumefactive lesions and allergic manifestations like atopy, eczema, asthma and peripheral blood eosinophilia ,5–7. TheIntrascrotal involvement by IgG4-RD has been reportedly limited to para-testicular structures, mostly in the form of a pseudotumour. Most of these cases had systemic disease with more than one organ involvement . WennigeThe gold standard diagnostic modality for this entity is histopathological examination. Diagnosis requires elevated IgG4+ plasma cells in the tissue and two out of these three characteristic histo-morphological features : 1) densElevated serum IgG4 levels (>135 mg/dl) are not mandatory for diagnosis but have shown consistent association with disease activity and show suppression after steroid therapy. IgG4-related disease responder index (RI) is a recently devised measure to ascertain the disease activity and monitor relapses during therapy. The use of imaging studies like CT scan, MRI and FDG-PET scan (18F-fluorodeoxyglucose positron emission tomography) is common for disease evaluation and depends on the organ involved and availability. Treatment with glucocorticoids is considered the first-line of management in patients with active disease. Response is prompt and is noted within days to weeks while remission is usually achieved within few months. IgG4-RD has been shown to have a chronic relapsing course and monitoring of disease activity is hence of prime importance. Recently, rituximab was introduced for treatment of this disease entity and shows promise (In conclusion, IgG4-RD can present as a tumour-like mass in a number of organs/anatomic sites. It may stay indolent for years or develop organ damage in a short period of time. Imaging studies cannot reliably distinguish between this entity and malignancy. Serum IgG4 levels may not be elevated in every case but they still serve as a marker for disease activity. Since the span of this illness encompasses a number of medical specialities, familiarity with this entity is imperative and it should be considered in the differential of any mass-forming lesion that shows typical histomorphology of this disease.The authors declare no conflict of interest.The authors received no financial support for the research, authorship, and/or publication of this article.


Rotator cuff tear (RCT) is a common shoulder condition frequently treated with arthroscopic rotator cuff repair (ARCR) after conservative interventions have failed. Postoperative shoulder stiffness (POSS) is a common complication after ARCR. The purpose of this study is to determine the incidence of POSS after ARCR in total and based on tear extent prior to ARCR. A systematic review was performed using PubMed, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Medical Literature Analysis and Retrieval System Online (MEDLINE), and ScienceDirect databases. The search terms were “rotator cuff repair” AND “arthrofibrosis” OR “postoperative shoulder stiffness.” Articles were selected based on ARCR and the presence of POSS documentation. Twenty-five articles out of 284 articles met the final selection criteria after reviewing for patients who received ARCR. Out of all patients , 597 had POSS (6.4%). Out of the 2,424 patients with a specified tear pattern, 96 out of 1,862 (5.2%) patients with full-thickness tears and 58 out of 562 (10.3%) patients with partial-thickness tears had POSS after ARCR. Partial-thickness tears are associated with higher rates of POSS after ARCR as compared to full-thickness tears (p<0.001). Overall, POSS is a common complication after ARCR with an incidence of 6.4%, regardless of tear type. POSS is more common in patients who receive ARCR for partial-thickness RCT (10.3%) as compared to patients who receive ARCR for full-thickness RCT (5.2%). More research is needed to determine other factors impacting the incidence of POSS after ARCR. Arthroscopic rotator cuff repair (ARCR) is a common surgical intervention viewed as the gold standard to address a rotator cuff tear (RCT) for which nonoperative treatment has failed -3. ARCR POSS after ARCR is a relevant concern as the development of POSS after ARCR has been reported to increase patient dissatisfaction and may decrease functional outcomes ,8. FurthMethodsThe current study is a systematic review of all relevant and full-text articles regarding POSS after ARCR found on the PubMed, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Medical Literature Analysis and Retrieval System Online (MEDLINE), and ScienceDirect databases without time restrictions. The current study included articles published up until the time of October 21, 2022, which was when the databases were searched with the full search terms. The full search terms used to retrieve articles in the four databases were “rotator cuff repair” AND “arthrofibrosis” OR “postoperative shoulder stiffness.” Multiple authors helped with article selection as well as data extraction. The article types included in the review were randomized controlled trials, retrospective cohort studies, and prospective cohort studies. Articles were initially screened by title and abstract. Articles were included if any number of cases of POSS, including zero cases, were specifically reported. For the current study, POSS was defined as any type of POSS, including postoperative arthrofibrosis and postoperative adhesive capsulitis. Studies were excluded from the final review if they did not report POSS incidence in the study population, did not report postoperative complications, or did not perform ARCR for rotator cuff repair. Furthermore, systematic reviews, meta-analyses, case series, and case reports were excluded from the study. Articles were selected based on full text and relevance based on ARCR and the occurrence of POSS of any type or severity. Articles were also grouped into categories by the type of RCT surgically corrected by ARCR. Groups were created by the information listed in the individual articles and included “partial” for partial-thickness tears, “full thickness” for full-thickness tears, and “all tears” if the tear type was not specified or used in the subgroup analysis. The chi-square test was used for statistical analysis to compare the incidence of ARCR for partial-thickness tears to the incidence of ARCR for full-thickness tears.ResultsA total of 284 articles were retrieved from PubMed, CINAHL, MEDLINE, and ScienceDirect with 25 articles meeting the final selection criteria for inclusion in the systematic review -29. FiguOf the 25 articles selected for the study, two studies were Level I evidence, three studies were Level II evidence, five studies were Level III evidence, and 15 studies were Level IV evidence. Table DiscussionThe current systematic review provides an updated incidence of POSS after ARCR based on tear type with one of the largest number of articles and patients to date on the topic of POSS. Knowledge concerning POSS after ARCR is crucial as POSS has been associated with decreased patient satisfaction after surgery, increased cost, and decreased outcomes ,4-6. TheIn the literature, the previously reported incidence levels of POSS after ARCR have been highly variable with rates reported as high as 35% three months after ARCR . The curThe current study found a significantly larger incidence of POSS after ARCR for partial-thickness tears at 10.3% as compared to an incidence of 5.2% of POSS after ARCR for full-thickness tears. This finding of increased incidence of POSS in patients after ARCR for partial-thickness tears has been reported elsewhere in the literature . InteresOne limitation of the current study is that the severity of POSS and the subsequent management, whether operative or nonoperative, is not known. Another limitation of this study is that the incidence of POSS after ARCR based on patient age or different time points after surgery is unknown. More research is needed to determine the incidence of POSS with a larger sample size that requires conservative versus surgical intervention and factors in patient age and follow-up time.Another limitation that complicates the discussion of POSS after ARCR is the lack of consistency in the definition of POSS. Many articles included in the current study did not provide definitions of POSS. Others provided various definitions of POSS after ARCR, which is consistent with the literature that indicates a wide variability in POSS definition . UnderstPOSS is a common complication after ARCR with an overall incidence of 6.4%, regardless of tear type. POSS was more common in patients who underwent ARCR for partial RCTs as compared to patients who underwent ARCR for full-thickness RCTs. The incidence of POSS after ARCR for partial-thickness tears was 10.3%, while the incidence of POSS after ARCR for full-thickness tears was 5.2%. Further research is needed to determine more factors contributing to POSS after ARCR, the severity of POSS, and the management of POSS after ARCR dependent on tear type.


Despite current therapies, lung cancer remains a global issue and requires the creation of novel treatment methods. Recent research has shown that biguanides such as metformin (MET) and silibinin (SIL) have a potential anticancer effect. As a consequence, the effectiveness of MET and SIL in combination against lung cancer cells was investigated in this study to develop an effective and novel treatment method.Niosomal nanoparticles were synthesized via the thin-film hydration method, and field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), atomic force microscopy (AFM), and dynamic light scattering (DLS) techniques were used to evaluate their physico-chemical characteristics. The cytotoxic effects of free and drug-loaded nanoparticles (NPs), as well as their combination, on A549 cells were assessed using the MTT assay. An apoptosis test was used while under the influence of medication to identify the molecular mechanisms behind programmed cell death. With the use of a cell cycle test, it was determined whether pharmaceutical effects caused the cell cycle to stop progressing. Additionally, the qRT-PCR technique was used to evaluate the levels of hTERT, BAX, and BCL-2 gene expression after 48-h medication treatment.In the cytotoxicity assay, the growth of A549 lung cancer cells was inhibited by both MET and SIL. Compared to the individual therapies, the combination of MET and SIL dramatically and synergistically decreased the IC50 values of MET and SIL in lung cancer cells. Furthermore, the combination of MET and SIL produced lower IC50 values and a better anti-proliferative effect on A549 lung cancer cells. Real-time PCR results showed that the expression levels of hTERT and BCL-2 were significantly reduced in lung cancer cell lines treated with MET and SIL compared to single treatments (p< 0.001).It is anticipated that the use of nano-niosomal-formed MET and SIL would improve lung cancer treatment outcomes and improve the therapeutic efficiency of lung cancer cells. It has anticancer effects in certain cancer forms, like breast, prostate, kidney, skin, pancreas, bladder, lung, and colon cancers. It also has hepato-protective, immune-stimulatory, cell cycle arrest, and antioxidant effects  were acquired from the Institut Pasteur Cell Bank, Iran (Cat. No C203), and maintained according to recommendations. Metformin , silibinin, dimethyl sulfoxide, 3--2,5-diphenyltetrazolium bromide (MTT), PEG , dimethyl sulfoxide (DMSO), polyvinyl alcohol (PVA) and cholesterol, non-ionic surfactants (Span-60), methanol, and chloroform were purchased from Sigma Aldrich . Fetal bovine serum (FBS), penicillin–streptomycin, and RPMI-1640 were taken from Gibco BRL . The first strand of complementary DNA (cDNA) synthesized with the kit purchased from Fermentas  and Syber Green PCR Master Mix kit was provided from Roche .2.2First, PEG (3 mg), cholesterol (6 mg), and Span-60 (36 mg) were dissolved in 10 ml of an ethanol/chloroform mixture. The solvent was evaporated using a rotary evaporator at 120 rpm and 60°C under reduced pressure. After the evaporation of the organic solvent, a thin film was formed at the bottom of the round-bottom flask. Then, the formed layer was hydrated with phosphate-buffered saline (PBS) containing MET (1.6 mg) and evaporated by a rotary evaporator at 90 rpm and 60°C. The obtained solvent was collected and sonicated using a sonicator for 30 min to get a uniform, smaller, and more homogenized niosome. To provide SIL-loaded PEGylated niosome, SIL (4.8 mg) was dissolved in a mixture of chloroform–ethanol with niosome. The samples were prepared and kept at 4°C for later analyses.2.3Dynamic light scattering (DLS) technique  was applied to evaluate the average size and surface charge of the prepared niosome. In summary, the niosome samples were properly diluted (1:10) with deionized water, and the sample size and zeta potential were measured according to the DLS method using Zetasizer Nano ZS  with a helium–neon laser at 630 nm in room temperature.2.4A field emission scanning electron microscopy (FE-SEM) model AIS 2100  was used to examine the surface morphology and microstructure of synthesized PEGylated niosome. A small number of samples were used for this, which were rinsed twice with pure water, freeze-dried, and scanned using an electron microscope.2.5Spectrophotometry was applied to evaluate the entrapment efficacy (EE). Initially, various doses of MET and SIL in methanol were used to adjust the calibration curve. After that, Amicon MPS  was used to load a niosome solution and centrifuged . The entrapped niosome remained at the top of the tube membrane, while the supernatant was detached from the bottom filter cup. The concentration of free MET and free SIL in the supernatant was recorded using absorbance measurements at 234 and 287 nm, respectively. The percentage of entrapment efficiency was calculated by the following formula:2.6−1.In order to distinguish between the loaded and unloaded drug in the niosome, Fourier transform infrared spectroscopy (FTIR) was used. After lyophilized into a dry powder, the samples were combined with potassium bromide. The specimens were then put into a hydraulic press to create pellets. The samples were scanned in the wavelength range of 400–4,000 cm2.72.A549 and HEK 293 cell lines were purchased from the Institut Pasteur cell culture collection . The cells were grown in RPMI-1640 medium complemented with FBS (10%), 0.05 mg/ml of penicillin G, and 0.08 mg/ml of streptomycin. Cells were placed in a sterile flask and incubated at 37°C in a humidified atmosphere containing 5% CO2.8in vitro release of MET and SIL from the niosome was assessed. A specified volume of MET-NP and SIL-NP was dispersed in PBS with pH values of 4.4 and 7.4, respectively. The release of both drugs was estimated in PBS while continuously agitating the MET and SIL niosome samples in the dialysis tubes. After that, the sample was periodically removed from the incubation medium and quickly replaced with an equivalent amount of fresh PBS. A UV–Vis spectrometer was applied to measure the release of MET and SIL at 234 and 287 nm, respectively.With the use of a dialysis bag (MW = 12 kDa), the 2.94 A549 lung cancer cells per well and incubated for 24 h at 37°C in a humidified atmosphere containing 5% CO2 to encourage cell adhesion. Furthermore, we applied human embryonic kidney 293 (HEK 293) as a normal cell line and evaluated the cytotoxicity of niosomal metformin and silibinin on this cell line. Then, the cells were exposed to various doses of the free and loaded forms of MET and SIL and their combinations listed in With the use of MTT assay, the cytotoxic properties of drugs were evaluated in their free, loaded, and combination forms. In summary, a 96-well plate was seeded with 2 × 102.106 A549 cells were seeded in six-well plates and incubated at 37°C with 5% CO2. After 24 h, cells were exposed separately to free-MET (F-MET), free-SIL (F-SIL), nano-MET (N-MET), nano-SIL (N-SIL), and a combination of F-MET-SIL and N-MET-SIL at their IC50 concentration. After 48-h treatment of free and drug-loaded NPs, total mRNA was extracted by TRIzol  reagent based on the instrument. Then, using measurements of the OD260/280 ratio, the quantity and quality of the total extracted mRNA were determined. Then, employing a first-strand cDNA synthesis kit , cDNA was synthesized from mRNA extracted from each sample in accordance with the manufacturer’s instruction. According to the manufacturer’s recommendations, hTERT, BAX, and BCL-2 gene expression levels were then assessed using the qPCR method employing the Hot Taq EvaGreen qPCR. The primer-blast on the National Center for Biotechnology Information (NCBI) website was used to blast the exact primers that were utilized for real-time PCR  and washed three times with PBS solution. Then, a certain amount of fixed solution was used to fix the cells. Annexin, V-FITC, and propidium iodide (PI) were then used to stain the cells, and they were incubated for 20 min. A flow cytometer was used to measure the cell mortality rate.Apoptosis induction was investigated by F-MET, F-SIL, N-MET, N-SIL, and their combination on the A549 cell line using a flow cytometer and Annexin V staining method. In summary, six-well plates containing 5 × 102.125 A549 cells were seeded per well of six-well plates and incubated for 24 h. Then, cells were treated with F-MET, F-SIL, N-MET, N-SIL, and their combinations. Following 48 h of drug exposure, the cells were collected and washed three times with PBS before being fixed with 70% ethanol and stored at −20°C for 48 h. The cells were taken, re-suspended in PBS, and stained with a solution that contains RNase A and PI; then, the cells were incubated for 30 min at 37°C. The fluorescence was read using the flow cytometer.A total of 5 × 102.13post-hoc test using GraphPad Prism (version 8). Results with p ≤ 0.05 were regarded as statistically significant and were represented as the mean ± standard deviation (SD). All experimental trials were conducted three times and reported as mean ± SD.Statistical significance and multi-group comparison of data were performed using a two-way analysis of variance (ANOVA) followed by Tukey’s 33.1in vivo to find their target sites before being digested by macrophages  analysis findings Figure 3−1 assigned to O–H and N–H bands, respectively, of polymer and drug. The peak at 2,362 cm−1 was related to MET C═N of imines stretching vibration. The peak at 2,362 cm−1 was related to MET C═N of imines stretching vibration. An intense peak at 1,759 cm−1 was the characteristic esoteric (O–C═O) bands of PEGylated niosome section. The peaks at 1,508–1,669 cm−1 are characteristic bands of NH primary bending, NH secondary bending, and C–N stretching vibrations of MET. Other characteristic peaks of –MET, which indicated C–C, C–O, and C–O–C, appeared at 1,059–1,187 cm−1. The FTIR spectrum of F-SIL showed a peak at 2,885 cm−1 attributed to C–H stretch of CH, and 3,010 and 2,955 cm−1 are due to C–H stretch of CH. A sharp peak at 1,630 cm−1 is attributed to C–O stretch. Absorption at 1,186–1,089.6 cm−1 is assigned to C–O stretch. The results display that MET and SIL have been successfully combined with PEGylated-niosome NPs. Our data were in agreement with the findings of Soumaye Amirsaadat et al.  values for pharmaceutical formulation against A549 cells after 48 h of incubation are shown in Dose effect evaluation of F-MET, F-SIL, N-MET, N-SIL, and their combination indicated that drugs in combination form have a greater effect than a single form. Moreover, our results showed that the combination of MET and SIL in the niosome has a higher effect on the A549 cell line as shown in 3.4To examine the anticancer effects of MET and SIL in free and encapsulation forms and their combination in the A549 cell line, the transcription levels of hTERT, BAX, and BCL-2 genes were measured by RT-PCR.BAX (pro-apoptotic) and BCL-2 (anti-apoptotic) belong to the BCL-2 family, which regulates the apoptosis process through the mitochondrial pathway . A recenAbnormal expression of telomerase is found in many cancers that have an essential role in the proliferation and immortality of tumor cells, which is a hallmark of cancer cells. This feature of telomerase becomes a potential target in cancer treatment and drug delivery . It is bIn our research, it is found that MET and SIL in free and nano-capsulated forms inhibited the expression of hTERT and BCL-2 while inducing the expression of BAX Figure 9Also, our results have discovered that F-MET/SIL and N-MET/SIL downregulate hTERT and BCL-2 and upregulate BAX more than individual forms. This proves that drug combination may enhance anticancer effects and have a synergistic inhibitory impact on tumor cells. This approach could be helpful to increase the therapeutic benefit of individual treatment, particularly in the elimination of obstacles such as tumor resistance and low drug efficiency. Our data are in agreement with those of a recent study that has shown that MET and SIL alone and in combination could inhibit hTERT gene expression .3.5To evaluate the anticancer effect of drugs, an apoptosis assay can be performed . ApoptosIn line with our results, Cheng-Chia Tsai et al. have shown that combined treatment of MET and SIL induces apoptosis in colorectal cancer, whereas there was no evidence of apoptosis in colorectal cancer cells when MET and SIL were used alone .3.6The cell cycle is highly regulated by a group of enzymes, proteins, cytokines, and specific cell cycle signaling pathways, which have a critical role in cellular proliferation and repair processes . Continu4In this study, we aimed to synthesize an effective delivery system of PEGylated niosome for metformin and silibinin and evaluated their anticancer effect against A549 lung cancer cells.in vivo experiments.The anticancer effect of the metformin and silibinin was increased when they were loaded in PEGylated niosomal NPs compared to the free form. This study exhibited that PEGylated niosomal NPs are an appropriate approach for the effective delivery of drugs for lung cancer cells. Metformin and silibinin in free and encapsulated forms induced apoptosis and cell cycle arrest in cancer cell lines. This evidence suggested that applying a combination of drugs in PEGylated niosomal NPs had a greater effect on inducing apoptosis cell cycle arrest. According to the result of qRT-PCR, the expression of hTERT and BCL-2 genes decreased significantly, while the expression of BAX increased in the treated A549 lung cancer cells. In particular, the downregulation of hTERT and BCL-2 and upregulation of BAX gene expression were enhanced when cells treated with the combination of metformin and silibinin were loaded into PEGylated niosomal NPs. Finally, it can be determined that a combination of metformin and silibinin in PEGylated niosomal NPs is an effective strategy for treating lung cancer, and future studies need to investigate the effects of these drugs in The data that support the findings of this study are available on request from the corresponding author.Writing—original draft preparation: ES-J. Editing: DJ-G and EB. Conceptualization and supervision: NZ. All authors contributed to the article and approved the submitted version.


Background and Objectives: Overprescribing of antibiotics is one of the important contributors of antimicrobial resistance globally. A high proportion of antibiotics prescribed in community settings are unnecessary or inappropriate. This study assesses the prescribing practices and factors related to antibiotic prescribing in community pharmacies in United Arab Emirates (UAE). Materials and Methods: A cross-sectional study utilizing a quantitative approach was carried out in the community pharmacies of Ras Al Khaimah (RAK), UAE. Six hundred and thirty prescription encounters from 21 randomly selected community pharmacies were investigated using World Health Organization (WHO) core prescribing indicators. Factors related to antibiotic prescribing were identified using logistic regression analyses. Results: In 630 prescription encounters, a total of 1814 drugs were prescribed. Out of these, the most commonly prescribed drug class was antibiotics (43.8% prescriptions) and the antibiotic was amoxicillin/clavulanic-acid (22.4%). The average number of drugs per prescription was 2.88, which was higher than the WHO recommended value of 1.6–1.8. In addition, more than half of the prescriptions (58.6%) had drugs by generic names and the majority of the drugs prescribed (83.8%) were from the essential drug list, which were lower than the optimal values of 100%. The majority of the antibiotics prescribed in the study were from the WHO’s Access group antibiotics. Multivariable logistic regression analysis identified patient age , prescriber qualification as general practitioner , and number of drugs per prescription  as independent factors associated with antibiotic prescribing. Conclusions: This study reveals considerable variations from the WHO recommendations for the different prescribing indicators in the community pharmacies of RAK, UAE. In addition, the study reports overprescribing of antibiotics in the community setting, indicating the need for interventions to promote rational use of antibiotics in a community setting. Community pharmacies play a vital role in the provision of pharmaceutical care services to patients in the community. These pharmacies are accessible and convenient for patients, which makes them an indispensable part of the healthcare system ,2. PatieRational use of medicines is essential as it ensures patient safety, optimizes therapeutic outcomes, prevents the development of drug-related problems, and reduces the overall cost of healthcare . The WorOverprescribing of antibiotics in primary care is one of the important contributors of antimicrobial resistance (AMR) globally . PreviouMany studies have assessed general and antibiotic specific prescribing practices employing WHO core indicators in different settings, community pharmacies ,19,20,21This descriptive cross-sectional study was carried out in the community pharmacies of RAK, which is one of the seven emirates of UAE and is situated in the northernmost part of the country with an estimated population of 345,000 . The stuThe UAE has a rapidly developing and high-quality healthcare system, with a mix of public and private healthcare providers serving a diverse multiethnic population. Ministry of Health and Prevention (MOHAP) is responsible for regulating healthcare services in the country and has implemented several initiatives aimed at improving healthcare quality and patient safety. According to UAE regulations, antibiotics are prescription-only medications and require a valid prescription from a registered medical practitioner. The MOHAP has launched several campaigns and initiatives aimed at promoting appropriate antibiotic use and preventing the emergence of antibiotic resistance .We stratified the community pharmacies located in RAK into five main geographical areas and randomly selected a sample of four or more pharmacies from each of these areas, taking into consideration the number of pharmacies present and the willingness of the community pharmacists to take part in the study. Following this stratified random sampling, 21 pharmacies were included in the study. According to the WHO, the minimum number of encounters required for prescription analysis is 600. Therefore, in the present study, 630 prescriptions were analyzed, with 30 prescriptions being selected randomly from each pharmacy. Prescriptions written by diverse medical professionals, including general practitioners and specialists, were collected and analyzed. Specialists were medical practitioners, such as physicians, pediatricians, gynecologists, cardiologists, dermatologists, ear, nose, and throat specialists, ophthalmologists, internal medicine specialists, and general surgeons.Study investigators collected data related to prescribing indicators in accordance with the WHO guidelines and methods. Data related to prescribing indicators included ‘average number of drugs per encounter, percentage of drugs prescribed by generic name, percentage of encounters with an antibiotic prescribed, percentage of encounters with an injection prescribed, percentage of drugs prescribed from essential drugs list or formulary’. In addition, data related to patient age and gender, prescriber qualification, pharmacist-related information, such as age, gender, qualification, work experience, position in pharmacy, type of pharmacy, and location of pharmacy, were collected.® SPSS® Statistics Software version 27.0 was used for data analysis. Before analyzing the data, the skewness and kurtosis were assessed. Data normality was confirmed by the Shapiro–Wilk test. Categorical variables were represented as frequency and percentage with 95% confidence intervals (CI). Continuous variables were represented as median and interquartile range with 95% CI. Chi square test or Fisher’s exact test was used for comparing categorical variables, while the two-sample median test was used for continuous variables. Factors related to antibiotic prescribing were identified using logistic regression analyses. The results were presented as odds ratios (OR) along with 95% CI. Significance level (α) was 0.05 for all statistical tests.IBMThe Ministry of Health and Prevention Research and Ethics Committee/RAK Subcommittee  and Ras Al Khaimah Medical and Health Sciences University Research and Ethics Committee  approved the study protocol.n = 342) were female and 45.7% (n = 288) were male with a median age of 29 years . Regarding the pharmacists in the community pharmacies, the majority were male  with a median experience of 5.0 years (IQR: 4.0–7.0), had a bachelor’s degree in pharmacy , had a designation as a pharmacist , received less than 100 prescriptions per day , and worked in independent type of pharmacies . The majority of the study prescriptions were written by general practitioners , followed by gynecologists  and pediatricians . Six hundred and thirty prescriptions were evaluated, belonging to 630 patients, of which 54.3% , had at least one drug prescribed by generic name , had no antibiotic encounter , had no encounter with injection , and had drugs from the essential drug list . In 630 prescription encounters, a total of 1814 drugs were prescribed. Out of these, the most commonly prescribed drug class was antibiotics (43.8% prescriptions), followed by antipyretics (30.6% prescriptions), non-steroidal anti-inflammatory drugs (27.1% prescriptions), and antihistamines (20.3% prescriptions). Among antibiotics, the commonly prescribed antibiotics were amoxicillin/clavulanic-acid (22.4%), azithromycin (4.4%), and cefixime (4.1%) . The majThe average number of drugs per prescription was 2.88, with antibiotics prescribed in 43.8% of the prescriptions, which were higher than the optimal values of 1.6–1.8 and 20.0–26.8%, respectively. More than half of the prescriptions (58.6%) had drugs by generic names and the majority of the drugs prescribed (83.8%) were from the essential drug list, which were lower than the optimal values of 100%. Furthermore, only three prescriptions had injections, accounting for 0.5% of all the encounters. Prescribed antibiotics were categorized into three groups, Access, Watch, and Reserve, as per the WHO’s AWaRe classification . The majp < 0.001; OR: 5.3, 95% CI: 1.4–18.95, p = 0.010, respectively) compared to older patients. In addition, general practitioners were more likely to prescribe antibiotics  compared to specialists. Moreover, prescriptions with a greater number of drugs were more likely to have antibiotics . Multivariable logistic regression analysis identified patient age  as the independent predictors of antibiotic prescribing in our study population. Furthermore, prescriber qualification as general practitioner  and number of drugs per prescription  were independently associated with antibiotic prescribing  and number of drugs per prescription were converted into categorical variables before putting them into the model. The analysis revealed that children and adolescent patients were more likely to be prescribed antibiotics  was significantly higher than the WHO recommendation of 20–26.2%  pointingThe WHO AWaRe classification system was developed to promote responsible prescribing behavior by increasing the use of antibiotics in the Access group and decreasing the use of antibiotics in the Watch and Reserve groups . AccordiPrevious studies have reported different factors associated with antibiotic prescribing, such as type of infection, antibiotic sensitivity tests, antibiotic availability in health facilities, prescriber’s qualification, knowledge, training, and experience, source of payment to prescribers, socio-economic status of patients, age of patients, etc. ,39,40. PIn this study, prescriber qualification was significantly associated with antibiotic prescribing, with general practitioners being more likely to prescribe antibiotics compared to specialists. This finding is in line with previous studies conducted in the United States  and GermThis study has some limitations. The study has limited generalizability, as it was conducted in a specific community pharmacy setting. The sample of community pharmacies and pharmacists included in the study may not be representative of all community pharmacies or pharmacists in the UAE. The cross-sectional design of the study limits causal conclusions, as it only captured a snapshot of prescribing practices and factors related to antibiotic prescribing at a single point in time. The unavailability of indication data for the prescribed antibiotics in the community pharmacies restricted the assessment of appropriateness of the antibiotics. The study did not take self-medication into consideration, which might have underestimated the antibiotic use in the study population. The study recorded only the number of co-prescribed medications with antibiotics and did not analyze specifically the individual co-prescribed drugs.This study reveals considerable variations from the WHO recommendations for the different prescribing indicators in community pharmacies. In addition, the study reports overprescribing of antibiotics in the community setting. However, the majority of the antibiotic prescriptions were from the WHO’s Access group antibiotics. Patient age and prescriber qualification were found to be the independent factors associated with antibiotic prescribing. The results of this study indicate the need for interventions to promote appropriate use of antibiotics, to educate healthcare providers and patients about the risks of overuse, and most importantly, to develop and implement antimicrobial stewardship programs that specifically focus on community and primary care settings.


Background: Total knee replacement (TKA) is becoming a routine procedure in orthopedic surgery. One of the possible complications of this surgery is periprosthetic joint infection (PJI). The purpose of this study is to identify, through a literature review, which antibiotic is used as prophylaxis for septic one-stage revision TKA and what is the rationale for its use. Methods: We searched: MEDLINE, Embase, PsycINFO on Ovid, the Cochrane Library, and the Google Scholar Database. The searches were limited by date (January 2005 to September 2022) and to the English language. All types of original research were considered, including prospective or retrospective longitudinal studies, cross-sectional studies, and randomized trials. The specific search terms were ((antibiotic [MeSH]) AND (prophylaxis)) and  adj2 (replace* OR arthroplasty* OR prosthe*))). Results: Despite our research efforts, we found no article capable of answering the question of which antibiotic to use as surgical prophylaxis for a septic revision one-stage TKA. Conclusions: Although the research results are inconclusive, we would recommend using the same antibiotic prophylaxis as for primary joint replacement, i.e., cefazolin, as it was recommended for its low side effect rate and relative effectiveness. Total knee arthroplasty (TKA) has become the option of choice both in terms of cost and success in the treatment of knee osteoarthritis (OA) ,2, one oIn 2011, the Musculoskeletal Infection Society (MSIS) and the International Society for Infectious Diseases (ISID) developed criteria to standardize the definition of PJI ,9. In 20Nowadays, many studies are still in progress to try to expand our knowledge on the diagnostics of this issue  ,10.The management of PJI is complex and reflects the multifactorial nature of the problem. Unfortunately, antibiotic therapy alone does not lead to satisfactory results or the complete recovery of the patient. Therefore, revision surgery through one or two stages might be performed. However, in the elderly, PJI surgery may result in a higher incidence of mortality ,11,12.One-stage revision for septic prosthesis has been studied and reported in a few centers ,17,18,19Prophylactic antibiotics reduce the risk of developing PJI ,22,23,24Looking at our experience in the revision of septic TKAs, we looked at the best management of patients undergoing one-stage surgery at the level of antibiotic prophylaxis and how this antibiotic management could act at the level of clinical outcome. The purpose of this article is to find, through a scoping review of the literature, which class or type of antibiotic used as prophylaxis for one-stage septic revision TKA might be recommended to lower the risk of reinfection, and what rationale, if any, or body of evidence supports the use of specific antibiotics for the prophylaxis of surgery in one-stage revision.The initial search identified 746 studies. After removing duplicates and studies not meeting the inclusion criteria, the review of titles and abstracts yielded 74 potential studies. All the selected studies were excluded during the full-text review for not describing antibiotic selection and administration, not reporting on PJI, or not including a control group  ,48.Enterobacteriaceae and Cutibacterium acnes ) AND (prophylaxis)) and  adj2 (replace* OR arthroplast* OR prosthe*))).Two independent reviewers (C.C. and B.B.) screened all the identified titles and abstracts. All randomized controlled trials (RCTs) as well as prospective cohort, retrospective cohort, and case-control studies pertaining to one-stage total knee revision arthroplasty, antibiotic prophylaxis for total revision knee arthroplasty, and antibiotic prophylaxis for total joint revision replacement were included.Potentially eligible studies were identified, and the full-text articles of these studies were retrieved for review. The reference lists of the full text articles and related citations were searched for relevant articles that were not identified in the original search. Our research strategy identified 74 studies .PJI is one of the most devastating complications of TKAs. The solution to this complication is almost always based on surgery. Based on the available data, it is not possible to make recommendations on antibiotic prophylaxis regimens for septic one-stage revision TKA. Our results demonstrate the need for further level I studies with adequate power to evaluate which class or type of antibiotic used as prophylaxis for septic TKA single-stage revision could be recommended to reduce the risk of reinfection. At present, we would suggest using the same antibiotic prophylaxis as for primary joint replacement.


Bridges are among the most vulnerable structures to earthquake damage. Most bridges are seismically inadequate due to outdated bridge design codes and poor construction methods in developing countries. Although expensive, experimental studies are useful in evaluating bridge piers. As an alternative, numerical tools are used to evaluate bridge piers, and many numerical techniques can be applied in this context. This study employs Abaqus/Explicit, a finite element program, to model bridge piers nonlinearly and validate the proposed computational method using experimental data. In the finite element program, a single bridge pier having a circular geometry that is being subjected to a monotonic lateral load is simulated. In order to depict damages, Concrete Damage Plasticity (CDP), a damage model based on plasticity, is adopted. Concrete crushing and tensile cracking are the primary failure mechanisms as per CDP. The CDP parameters are determined by employing modified Kent and Park model for concrete compressive behavior and an exponential relation for tension stiffening. The performance of the bridge pier is investigated using an existing evaluation criterion. The influence of the stress–strain relation, the compressive strength of concrete, and geometric configuration are taken into consideration during the parametric analysis. It has been observed that the stress–strain relation, concrete strength, and configuration all have a significant impact on the column response. The Chi-Chi earthquake in 1999, which had a magnitude of 7.3, damaged or caused the collapse of about 200 bridges2. Similarly, in the 2008 Wenchuan earthquake, 6140 bridges either collapsed or suffered damages, and the transportation system suffered a loss of 67 billion RMB3. Significant changes were made in the seismic design of bridges in the Chinese code after the 2008 Wenchuan earthquake. In the 2005 Kashmir earthquake, many bridges suffered damages, with some experiencing damages beyond repair. A survey of the existing bridge stock of Pakistan was conducted in the wake of the 2005 earthquake4. It was ascertained that, out of the 6000 bridges surveyed, almost 67% of bridges on the major highways were constructed in the mid-80s. In addition, the official bridge design code of Pakistan, West Pakistan Code of Highways Practice, is adopted from the 1965 version of AASHTO, which was developed before the recent advances in the seismic design of bridges. All these factors collectively contributed to the poor performance of the bridges in the 2005 earthquake. Furthermore, it is also evident that given the aforementioned factors, the existing bridge stock of Pakistan is seismically vulnerable.A bridge is an integral component of the transportation network. Unlike other highway structures, its failure for any reason can have serious economic and life consequences. Among the different natural disasters, earthquakes pose more danger to bridges due to their unpredictable nature. More than 40 deaths and $1.8 billion loss occurred in the Loma Prieta earthquake due to bridge damages5. However, two test techniques, dynamic shake table testing and quasi-static reverse cyclic testing, are often used to evaluate the dynamic behavior of bridge piers. Experimental studies are significant in the seismic assessment of bridge piers, but the experimental tests cannot always be performed with the full-scale models due to the limitation imposed by space, time and equipment requirements6. Ali7 and Iqbal8 performed quasi-static cyclic testing on scaled-down models to study the behavior of low-strength concrete bridge piers. Deng et al.9 and Prakash et al.10 studied the effect of combined axial share, bending, and torsion on the bridge piers. Schoettler et al.11 and Sakai and Unjoh12 analyzed the effect of dynamic excitation on the behavior of bridge piers. Hose and Seible13 developed a damage assessment and performance evaluation criteria for post-earthquake evaluation of bridge piers. A 5-level qualitative performance evaluation criteria was presented and verified by a series of experimental tests on multiple bridge piers with different geometries.An experimental test for the lateral response of the structure can be carried out with four distinct methods15. Generally, nonlinear behavior of bridge piers can be assessed using numerical simulations. The three main numerical techniques employed in this regard are lumped plasticity, distributed plasticity (fiber-section approach) and finite element-based model approach (FEM). The FEM-based approach has been found to predict the non-linear behavior of concrete structures more realistically. In addition to this FEM based approach also can predict a detailed behavior incorporating a more exact failure mechanism of structure16. Deng et al.9 used Abaqus to analyze rebar stains under the influence of axial, bending shear, and torsion. Modeling concrete was achieved using the integrated concrete damaged plasticity model (CDP). Kishi et al.17 investigated the effect of the softening branch of concrete compressive behaviour on bridge pier damages. Using Abaqus CDP, Dawood et al.18 investigated the behaviour of segmentally post-tensioned concrete bridge piers. The performance of Abaqus CDP under reverse cyclic analysis of bridge piers was investigated by19. CDP with viscous regularizing was compared to the SDP  was observed during the on-field testing, with average strength up to 17.2 MPa (2494 psi). In light of the above, an experimental test was carried out to assess the seismic behavior of low-strength concrete bridge piers.After the 2005 earthquake, an extensive survey was carried out in the affected areas of PakistanThe geometry of the bridge pier is shown in Fig. The cross-sectional details are shown in Fig. 7. The 4 × 4 feet slabs for the dead load were reinforced with 3 number of 0.5 in. diameter bars in both directions. The single 8 × 8 foot slab was reinforced with 0.5 in. rebars having a spacing of 5 in. The top pedestal was reinforced with 0.5 in. grade 60 rebars at 4.5 in. center to center spacing.Table The equipment’s used for the testing included a hydraulic actuator having 50-ton capacity. Another hydraulic actuator having a 25-ton capacity was also utilized to perfrom the test in a cyclic quasi static manner. Both of the actuator had a speed of 0.256in./sec. Load cells were attached to the actuator to measure the applied forces. The hydraulic jacks were mounted on structural framing having adjustable girders. In addition to this the displacement at the load application point was measured with the help of linear variable deferential transformer (LVDT) and string potentiometer. A data acquisition system (UCAM-70) was used for the quasi-static testing data having 30 channels. The anchoring of the column base was achieved through four, 44-in.-long anchor having diameter of 1.75 in. Similarly, to anchor the slabs with the top of the column the four, 27-in.-long anchor having diameter of 1 in. were used.The column was subjected to quasi-static reverse cyclic loading. The loading protocol adopted for the column consisted of three cycles per drift level. A total of 37 cycles were applied, with a maximum of 4% drift in the final cycle. These loads were applied through a 50-ton Hydraulic actuator. The total time taken by the test was 3600 s.22. It offers both implicit and explicit analysis options for non-linear modeling. Modeling in the Abaqus is usually carried out using the sequence: geometry, material, assembly, contacts, loads and boundary condition, analysis, and post-processing. Some of the limitations of Abaqus modeling include that it needs high computational power for three dimensional simulations. Rebar rupture and concrete cracking cannot be explicitly modeled as well. A higher mesh size could overestimate the damage region while using CDP. Additionally, the CDP concrete model does not shows any convincing results in reverse cyclic condition19. Some of the potential sources of errors are inaccurate material data input for the CDP model, inaccurate constraints between the different concrete components and highly distorted mesh elements. Abaqus offers two main material constitutive models for concrete Structures: concrete damaged plasticity (CDP), which is available both in Abaqus/Standard and Abaqus/explicit and smeared cracking model used only in Abaqus/Standard. CDP was employed for the nonlinear modeling of concrete. The concrete elements were meshed using the C3D8 elements, which has 2 × 2 × 2 integration scheme. Rebars were model using the two-node linear truss T3D2 element due to their result accuracy and minimum computational effort21. The embedded constraint was employed for the interaction between rebars and concrete, while the interaction between the concrete surfaces was modeled through tie constraints. To avoid the relative movement of the base, the Encastre boundary condition was applied on the base of the footing. Rebars material was modeled using the simple bilinear elastoplastic law.Abaqus was used for the bridge pier's numerical modeling. Abaqus is a general-purpose finite element method (FEM) program that can evaluate static and dynamic problems in concrete structures22. Additionally, implicit analysis was employed initially, however, the computational time could not be determined because of the convergence errors which lead to simulation stoppage. Generally, with regard to the computational efficiency, the analysis time in Abaqus/explicit is proportional to the number of elements which in our case is 9094 elements. While, the analysis time in implicit solver is roughly proportional to the square of number of degrees of freedom . Hence, for the analysis, Abaqus explicit solver was employed with double precision. The model developed in Abaqus is shown in Fig. Material degradation and failure leads to severe convergence difficulties in implicit analysis which involves inversion of stiffens matrix. An example of material degradation is concrete cracking which leads to the formation of negative stiffness matrix23 and further modified by Lee and Fenves24, is based on the model of Continuum Plasticity damaged. The model considers cracking in tension and crushing in compression as the main failure mechanism of concrete. Similar to all plasticity based models, CDP requires a yield function, flow rule and hardening rule. The yield function in the deviatoric plane is shown in Fig. To model damages observed during the experiment, Abaqus CDP was employed for modeling concrete. The damage plasticity model for concrete, CDP, first given by Lubliner et al.The effective part of hydrostatic stress entclass1pt{minima as Eqs. , respectThe other parameters of the function are Eqs. –6)4\doc4\doc6)4\23. Typical experimental values of the ratio CDP's plastic potential function is a non-associated Drucker-Prager hyperbolic function defined by Eq. .7\docume25. Values for the rest of the parameters are adopted from the Abaqus manual, which are commonly employed and also recommended by25. Table 26.The eccentricity ϵ and dilation angle  and the value of 2796 ksi  was used for the numerical modeling and a value of 0.2 was used for the Poisson ratio.27 model shown in Fig. In compression, the concrete behaves elastically up to a certain limit, mostly in the range of 40–50%. After the initial elastic response, the inelastic region is characterized by an initial stress hardening region up to the peak stress, followed by strain softening in the post-peak branch. The modified Kent and Park28. In the later model, a crack opening displacement and stress relation is used to simulate the concrete's tensile behavior. The crack opening displacement and stress relation can be represented with a linear, bilinear, or exponential relation using the fracture energy criterion, as illustrated in Fig. 22 and therefore are avoided in modeling the post-peak tensile behavior of the concrete. The exponential relation given in29 is employed for the tension stiffening behavior. The equations  also contributes to the oscillations. The Butterworth filter in Abaqus is employed in the post processing phase of the modeling to remove the unwanted oscillations. The cutoff frequency of 0.1 Hz was selected due to similar output sampling frequency. Figure Meshing can significantly affect the computational time and results of a numerical study. For computational efficiency, it is necessary to conduct sensitivity analysis so that an optimum size and configuration of mesh is selected without compromising the numerical results. Load response behavior and damage patterns were the parameters used for the validation of optimum mesh size and configurations selection.32. Therefore, the model was initially tested with a localized mesh configuration in which the column and the footing nearby the columns were discretized with the same mesh size which was used for the initial validation. To further investigate the effect of mesh two more configurations were used: a complete instance mesh, where the entire model was meshed at once and a mesh ratio of 1.5 between the footing and column mesh. A mesh size of 2-in. was used for all these configurations. The load response curves of all these mesh configurations are shown in Fig. The interaction between the various surfaces is influenced by the meshThe load response behavior of the instance mesh shows a significant deviation from the actual load response behavior. The peak load observed in the instance mesh configuration is close to 6207 lbs. which is more (8% greater) the actual test. The 1.5 mesh ratio configuration does not depict any convincing behavior. The peak load observed is 3728 lb. which is 35% less than the actual load. The trend of the load-response in the case of 1.5 mesh ratio almost follows a flat plateau after peak load and does not gives any convincing result. In contrast to these, the localized mesh shows a convincing behavior and follows the experimental curve very closely and the peak load is 5340 lbs. (8% difference). The peak load difference is same for the instance mesh and localized mesh, however the later shows a more overall close behavior.In addition to this, mesh size effects were also investigated. 1-in. 2-in. and 3-in. mesh sizes were used using the localized configuration scheme. Comparisons of computational time and load response behavior of the mesh size effects are given in the Fig. Abaqus CDP uses two hardening variables, these are the It can be seen from the experimental backbone curve that there is a significant loss of load carrying capacity after the peak load. The same behavior is also observed in the numerical model with the experimental stress-strain relation. Damage comparison of all the three constitutive relation are also given in Fig. 13 developed a five-level performance and damage assessment criteria for the evaluation of bridge piers after an earthquake. The damages criteria is based on their socio- economic impact. These damage levels are then connected with the performance level through qualitative descriptions of damages for detail see13. Same performance evaluation criteria13 have been used for the assessment as given in Table 7, only performance level 3 comes in good agreement with the test column. Performance level 1, 2 and 4 have significant difference in terms of drift ratio as well as load. This difference in the performance levels is attributed to the difference in the concrete analytical and real behavior as well as the strain hardening effect of rebar. The initial stiffness of the experimental stress–strain relation as shown in Fig. Hose and Seible33 employed a value of 13. Tong et al.19 Employed 20 to represent the cyclic behavior of a concrete column. The non-linear behavior of a three-dimensional beam was studied by34 using dilation angles ranging from 20 to 50. Wosatko et al.26 studied the impacts of dilatancy on punching shear demand using dilation angles ranging from 5 to 55. In order to investigate the effect of the dilation angle on the behavior of the model, a dilation angle of 40 was first employed in this study. Subsequent analysis was then done on angles ranging from 1 to 40. The analysis' findings are presented in Fig. The change in the material's volume as a result of failure is referred to as dilation. It is one of the variables that contribute to the plastic potential function of the CDP. Regarding the values of the dilation angle, there is no agreement in the literature; different researchers have chosen different values for different structures. For the analysis of a reinforced concrete frame, Alfarah et al.4 revealed that existing bridge piers had concrete with a strength as low as 1800 psi, hence, 1800 psi strength concrete was selected as one of the target concrete strength for the parametric analysis. The study also investigates 4000 psi strength concrete, which is frequently utilized in reinforced concrete piers. The ACI  equation was used to estimate the concrete's modulus of elasticity. Similar CDP parameters to those of the 2400 psi concrete were utilized to simulate concrete behavior under compression using the confined Kent and Park model.Employing the computational method used previously in the sections above, bridge pier with concrete strengths of 1800 and 4000 psi were simulated to determine the effect of concrete strength on the performance. A survey byThe columns' performance levels were compared to the numerically tested circular column with a concrete strength of 2400 psi, illustrated in Figs. The influence on level of performance due to the variation in geometric shape of the column was explored using the given numerical scheme. Based on their equal cross sectional areas, the geometries of a single square and two rectangular columns were chosen at random. Initially, a 266 mm square column was modeled. A length to breadth ratio of 1.5 and 2 was used in the modeling of the rectangular columns. We will also use the terms 1.5R and 2R to refer to the rectangular columns having length to width ratio of 1.5 and 2, respectively. A 2400 psi concrete strength was chosen, and the initial model's longitudinal and transverse reinforcement was maintained. Instead of spirals, rectangular stirrups with spacing corresponding to the spiral's pitch in the initial circular column were modeled. Figure Figure 35 investigation also confirms the formation of four plastic hinges in the lateral directions, even though the investigation of35 was based on circular columns with different material properties and dimensions.To investigate the behavior of multiple column bridge piers under lateral loads, twin column configuration in addition to the single column configuration is also modeled. The twin column configuration uses the same column dimensions and reinforcement details as the single circular column as seen in Fig. In contrast to macro scale models, the scheme suggested in this study allows for a complete non-linear analysis and explicitly provides us with the peak load, rebar yielding, and pattern of damage.The slope of the falling branch of the compression stress–strain curve controls post-peak behavior. Actual stress–strain data for concrete from an experimental test produces results that are comparably more consistent than those from an analytical stress–strain relation. As shown, the falling branch of the load response curve form the actual stress–strain relation is more close to the actual load-response than the rest of the concrete models. The difference between the final failure load is almost 25% between the actual test and models with analytical relation, while this difference is negligible in case of the model with the experimental stress–strain relation.Mesh size and configurations should be thoroughly investigated. As shown in this study, these factors have significant influence on the overall damages profile as well as load response behavior.It was shown that when utilizing an explicit approach, the dilation angle had no noticeable effect on the genearl behavior of model, however, an angle of 40 gives a curve that follows the actual one more closely.The suggested computational method does not produce a plausible overall behavior in terms of the damages or the overall performance for geometries other than circular forms and the parameters developed for the circular geometry should be modified based on sensitivity analysis for other geometries.Peak loads and performance levels are significantly influenced by the strength of the concrete. Peak loads for concrete with a 4000 psi strength increased by about 27% while those for concrete with an 1800 psi strength decreased by 15%.The twin column arrangement exhibits high levels of performance and peak load that is almost five times higher  than that of a single column because of the production of multiple plastic hinges. However, due to similar geometric and material characteristics used for both the twin column and single circular column, higher ductility cannot be achieved.Concrete's behavior is substantially impacted by the stress–strain law; therefore, experimental stress–strain data should be employed, if available. It is possible to prevent difference in the load-deformation curve by using strain hardening relations for rebar. In order to assess performance level 5, the present explicit scheme used truss elements to imitate rebars; however, beam elements should be taken into account in place of truss elements to evaluate performance level 5. While using the current computational scheme, sufficient sensitivity analysis should be done for geometries other than circular shapes.In this paper, a computational method was suggested utilizing the Abaqus explicit solver, for the nonlinear behavior of bridge piers. The main parameters evaluated in this study are the load-response behavior and damages in RC bridge piers. The created model comprises a single circular column that is 146 in. long and 12 in. in diameter. In the model, concrete with a 2400 psi strength was employed. Using force-response relation, the model was calibrated against an experimental test. Then, parametric analyses were performed on the calibrated model in order to determine the impact of the stress–strain law, compressive strength, geometry, and configuration on the behavior of bridge pier. Following conclusions were made in this study.


Outpatient antibiotic prescribing decreased during the COVID-19 pandemic. Understanding how antibiotic prescribing habits changed differentially based on physician and practice characteristics presents an opportunity to inform antibiotic stewardship. Our objective was to evaluate inter-physician variability and predictors of changes in antibiotic prescribing before (2019) and during (2020/2021) the COVID-19 pandemic.We conducted a retrospective cohort analysis of physicians in Ontario, Canada prescribing oral antibiotics in the outpatient setting between 1 January 2019 and 31 December 2021 using the IQVIA Xponent dataset. The primary outcome was the change in the number of antibiotic prescriptions between the pre-pandemic and pandemic period. Secondary outcomes were changes in the selection of broad-spectrum agents and long-duration ( >7 days) antibiotic use. We used multivariable linear regression models to evaluate physician- and practice-level predictors of change.There were 17,288 physicians included in the study with substantial inter-physician variability in changes in antibiotic prescribing . In the multivariable model, later career stage , family medicine , male patient sex , low patient comorbidity , and high prescribing to new patients  were associated with decreases in antibiotic initiation. Family medicine and high prescribing to new patients were associated with significant decreases in selection of broad-spectrum agents and prolonged antibiotic use.Antibiotic prescribing changed throughout the COVID-19 pandemic with overall decreases in antibiotic initiation, broad-spectrum agents, and prolonged antibiotic courses with inter-physician variability. These findings present opportunities for targeted community antibiotic stewardship interventions.All Authors: No reported disclosures