Acinetobacter comprises species with ecological significance and opportunistic pathogens and has a complicated taxonomy. Precise species identification is a foundation for understanding bacteria. In this study, we found and characterized two novel Acinetobacter species, namely, Acinetobacter tianfuensis sp. nov. and Acinetobacter rongchengensis sp. nov., based on phenotype examinations and genome analyses of the two strains WCHAc060012T and WCHAc060115T. The two strains had ≤89.69%  average nucleotide identity (ANI) and ≤36.4%  in silico DNA-DNA hybridization (isDDH) values compared with each other and all known Acinetobacter species. Both species can be differentiated from all hitherto known Acinetobacter species by a combination of phenotypic characteristics. We found that Acinetobacter pullorum B301T and Acinetobacter portensis AC 877T are actually the same species with 98.59% ANI and 90.4% isDDH values. We then applied the updated taxonomy to curate 3,956 Acinetobacter genomes in GenBank and found that 6% of Acinetobacter genomes (n = 234) are required to be corrected or updated. We identified 56 novel tentative Acinetobacter species, extending the number of Acinetobacter species to 144, including 68 with species names and 76 unnamed taxa. We also found that ANI and the average amino acid identity (AAI) values among type or reference strains of all Acinetobacter species and taxa are ≥76.97% and ≥66.5%, respectively, which are higher than the proposed cutoffs to define the genus boundary. This study highlights the complex taxonomy of Acinetobacter as a single genus and the paramount importance of precise species identification. The newly identified unnamed taxa warrant further studies.The genus IMPORTANCEAcinetobacter species are widely distributed in nature and are of important ecological significance and clinical relevance. In this study, first, we significantly update the taxonomy of Acinetobacter by reporting two novel Acinetobacter species, namely, Acinetobacter tianfuensis and Acinetobacter rongchengensis, and by identifying Acinetobacter portensis as a synonym of Acinetobacter pullorum. Second, we curated Acinetobacter genome sequences deposited in GenBank  using the updated taxonomy by correcting species assignations for 6% (n = 234) genomes and by assigning 94 (2.4%) to 56 previously unknown tentative species (taxa). Therefore, after curation, we further update the genus Acinetobacter to comprise 144 species, including 68 with species names and 76 unnamed taxa. Third, we addressed the question of whether such a large number of species should be divided in different genera and found that Acinetobacter is indeed a single genus. Our study significantly advanced the taxonomy of Acinetobacter, an important genus with science and health implications. Acinetobacter, first proposed by Brisou and Prévot . Validly published names refer to those published in the International Journal of Systematic and Evolutionary Microbiology, the official journal of the International Committee on Systematics of Prokaryotes, including its validation lists . Therefore, there is a need to update the taxonomy of Acinetobacter and to curate the species assignations of Acinetobacter genome sequences deposited in GenBank.The genus d Prévot , is a hind water  and possnd water , 4. Somefections –8. Preciections –, 10. Befed names  and 20 aon lists . New Aci in 2020 , 13–18. onyms 19–. In addionyms 19–, 24 , and we identified 56 previously unknown tentative species designations.Here, we report two novel Acinetobacter strains, namely, WCHAc060012T and WCHAc060115T, were recovered from hospital sewage using an Acinetobacter chromogenic agar plate in 2018. We obtained the nearly complete 16S rRNA gene sequences  of the two strains using PCR with the universal primers 27F and 1492R  and Acinetobacter chinensis WCHAc010005T , respectively. However, it is well known that analysis based on the 16S rRNA sequence is insufficient for accurate taxonomic assignment (rpoB sequences (861 bp) of the two strains with those of Acinetobacter type strains. The two strains were also distinct from all known Acinetobacter species and formed two evolutionary clades in the phylogenetic tree based on partial rpoB gene sequences , while WCHAc060115T had the highest identity with Acinetobacter piscicola KCTC 62134T (95.23%).Two nd 1492R  and Sangnd 1492R  for prelsignment . We then10.1128/mSystems.00237-21.1FIG S1T, WCHAc060115T, and type strains of Acinetobacter species with validly published names. The sequence of Moraxella lacunata ATCC 17967T (GenBank accession no. AF005160) was used as the outgroup. Bootstrap values (≥50%) after 1,000 resamplings are indicated at branch nodes. Shown in parentheses are the DDBJ/ENA/GenBank accession no. for 16S rRNA gene sequences or whole-genome sequences. Bar, 0.2 substitutions per nucleotide position. Download FIG S1, PDF file, 2.6 MB.Maximum likelihood phylogenetic tree based on 16S rRNA gene sequences  of WCHAc060012Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the 10.1128/mSystems.00237-21.2FIG S2rpoB (861 bp) gene sequences of WCHAc060012T, WCHAc060115T, and type strains of Acinetobacter species with validly published names. Evolutionary distances were computed using Kimura’s two-parameter model. Moraxella lacunata ATCC 17967T was used as the outgroup. Bootstrap values ≥ 50% based on 1,000 resamplings are shown. Shown in parentheses are the DDBJ/ENA/GenBank accession no. for rpoB gene sequences or whole-genome sequences. Bar, 0.2 substitutions per nucleotide position. Download FIG S2, PDF file, 2.3 MB.Maximum likelihood phylogenetic tree based on partial Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the T, 6,401,206 reads and 1.92 giga-bases (Gb) were generated with an actual 549.9× coverage, which were assembled into a 3.5-Mb draft genome sequence containing 116 contigs  with a G+C content of 42.3% . For strain WCHAc060115T, 5,479,547 reads and 1.64 Gb were generated with an actual 396.8 × coverage, which were assembled into a 4.1-Mb draft genome sequence containing 248 contigs  with a G+C content of 37.7%. We determined the average nucleotide identity (ANI) values between WCHAc060012T and WCHAc060115T and between the two strains and type strains of all Acinetobacter species. Compared with type strains of all Acinetobacter species, ANI values of WCHAc060012T ranged from 77.09% (Acinetobacter puyangensis ANC 4466T) to 82.70% (Acinetobacter cumulans WCHAc060092T), while those of WCHAc060115T ranged from 77.71% (A. puyangensis ANC 4466T) to 89.69% (Acinetobacterpiscicola LW15T) (T and WCHAc060115T was 79.46% (in silico DNA-DNA hybridization (isDDH) analyses for WCHAc060012T, WCHAc060115T, and type strains of all Acinetobacter species. The isDDH values of WCHAc060012T and type strains of all Acinetobacter species were 19.2% to 23.4%, while those of WCHAc060115T and type strains of all Acinetobacter species were 20.0% to 36.4%  . The ANIs 79.46% . These As 79.46% . We thento 36.4% , which ato 36.4% , 31. Theas 21.7% . Both ANre genes , WCHAc06T with the name Acinetobactertianfuensis sp. nov.  and WCHAc060115T with the name Acinetobacterrongchengensis sp. nov. . The type strain of Acinetobactertianfuensis and Acinetobacterrongchengensis is WCHAc060012T (=GDMCC 1.1623T =JCM 33510T) and WCHAc060115T (=GDMCC 1.1625T =JCM 33512T), respectively.After phenotypic characterizations (see below), we propose strain WCHAc060012Acinetobacter species, together with those for all known Acinetobacter species with validly published names, are summarized in T grows at 30°C in the presence of 0% to 3% (wt/vol) NaCl in tryptic soy broth (TSB), while WCHAc060115T grows in 0% to 4% (wt/vol) NaCl. Both strains were positive for the catalase test but negative for the oxidase activity. Cells of the two strains are Gram-negative coccobacilli; strictly aerobic; nonsporogenous; incapable of swimming motility; and capable of growing on media such as tryptic soy agar (TSA), Luria-Bertani (LB) agar, BHI agar, and Müller-Hinton agar . Colonies are light yellow, circular, opaque, smooth, convex, with entire margins, and approximately 1.0 to 2.0 mm in diameter after 24 h of incubation at 30°C on BHI agar plates.The phenotypic characteristics tested using the genus-targeted set of physiological and metabolic tests are presented in the standard way used in previous nomenclatural proposals , 33. The10.1128/mSystems.00237-21.6DATA SET S1A. tianfuensis sp. nov., A. rongchengensis sp. nov. and the Acinetobacter species with validly published names. Download Data Set S1, XLSX file, 0.03 MB.Phenotypic properties of Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the Acinetobacter species and each of the known species with validly published names are indicated in T from all known Acinetobacter species include growth on l-glutamate, d-malate, malonate, and phenylacetate but no growth on l-arabinose, l-arginine, azelate, and glutarate , and l-tartrate but not β-alanine and 4-aminobutyrate .We also identified antimicrobial resistance genes from genome sequences of the two strains  and that of A. portensis AC 877T (GenBank accession no. LWRV00000000) have a 90.4% isDDH value and a 98.59% ANI value. Both ANI and isDDH analyses clearly indicate that the two species are actually the same species. In the phylogenomic tree, A. pullorum B301T and A. portensis AC 877T indeed cluster together  . Before curation, we performed a quality-control check for all of the genomes. Among the 5,997 genomes, 2,041 were discarded due to low quality defined by >300 contigs for individual genomes (n = 444), a <50-kb N50 value (n = 458), <90% genome completeness (n = 20), genome contamination (n = 206), or genome heterogeneity (n = 913). We then used the remaining 3,956 genomes for precise species identification by both ANI and isDDH. Among the 3,956 Acinetobacter genomes, 3,777 were labeled with a known Acinetobacter species name (Acinetobacter sp. (n = 175), Acinetobacter genomosp. (n = 2), Acinetobacter calcoaceticus/Acinetobacter baumannii complex (n = 1), or uncultured Acinetobacter (n = 1)  or updated (n = 179) according to the findings in this study  . We thenies name . The rem (n = 1) , which w species , while tis study .10.1128/mSystems.00237-21.5TABLE S3Acinetobacter genome sequences with misidentified species in NCBI. Download Table S3, PDF file, 0.1 MB.The 55 Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the 10.1128/mSystems.00237-21.7DATA SET S2Acinetobacter genome sequences available in GenBank (accessed by 1 August 2020). Download Data Set S2, XLSX file, 0.4 MB.The 3,956 Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the Acinetobacter strains with genome sequences available, most  belonged to A. baumannii, followed by Acinetobacter pittii , Acinetobacter nosocomialis , and Acinetobacter indicus   values among type strains of all species and reference strains of all taxa of the genus Acinetobacter were also calculated, which are >66% (66.5% to 97.4%)  see . To furt.4%) see , 35. Bot10.1128/mSystems.00237-21.9DATA SET S4Acinetobacter species and reference strains of Acinetobacter taxa without species names. Download Data Set S4, XLSX file, 0.1 MB.Average nucleotide identity between type strains of Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the 10.1128/mSystems.00237-21.10DATA SET S5Acinetobacter species and reference strains of Acinetobacter taxa without species names. Download Data Set S5, XLSX file, 0.1 MB.Average amino acid identity between type strains of Copyright © 2021 Qin et al.2021Qin et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the Acinetobacter species. We also found that A. pullorum and A. portensis are synonyms and then updated the taxonomy of the genus Acinetobacter. We applied the updated taxonomic assignments to curate genome sequences deposited in GenBank with the label of Acinetobacter and found that 6% (n = 234) of the 3,956 genomes with good quality need to be corrected or updated for species identification. We also identified 56 previously unknown tentative species designations, which further update the genus Acinetobacter to comprise 144 species, including 68 with species names and 76 taxa without species names. Such a large number of species raises the question whether Acinetobacter should be divided into multiple genera. Although the boundary of bacterial genera based on genome sequences is less established than that of species and requires more studies , and l-tartrate but not β-alanine and 4-aminobutyrate. We also found that A. portensis is a later heterotypic synonym of A. pullorum. We demonstrated that some Acinetobacter genome sequences deposited in GenBank are required to be corrected and identified 56 novel tentative Acinetobacter taxa, which warrant further phenotype-based characterizations.In conclusion, we characterized and reported two novel Acinetobacter chromogenic agar plate . The plate was then incubated at 30°C overnight. All isolates recovered from the plate were subjected to preliminary species identification by partial sequencing of the RNA polymerase β subunit-encoding rpoB gene using PCR and Sanger sequencing as described previously  to type strains of all known Acinetobacter species may belong to novel species and were characterized as described below. Two Acinetobacter isolates, namely, WCHAc060012T and WCHAc060115T, were recovered from the plate and had ≤98% identity of the 861-bp partial rpoB sequence to type strains of all known Acinetobacter species.Hospital sewage (1 ml) was collected from the influx mainstream of the wastewater treatment plant at West China Hospital in June 2018, which was added in 10 ml nutrient broth  and was incubated overnight at 30°C with shaking. The culture suspension was diluted to 0.5 McFarland standard and was then further diluted to 1:100 with saline. A 100-μl aliquot was then streaked onto an T and WCHAc060115T were obtained using PCR with universal primers 27F and 1492R  were aligned using MAFFT v7.471  to query the ResFinder database 4.1 (https://cge.cbs.dtu.dk/services/ResFinder/).Genomic DNA from an overnight culture of each of the two strains was prepared using the QIAamp DNA minikit  and was then subjected to whole-genome sequencing using the HiSeq X10 sequencing platform  with an approximate 250× coverage. Reads were  v3.15.1 . PotentiM v1.1.3 . AntimicAcinetobacter species (T and WCHAc060115T were compared with those of type strains of Acinetobacter species using the average nucleotide identity based on BLAST (ANI) and in silico DNA-DNA hybridization (isDDH). ANI and isDDH values were calculated using the fastANI v1.32 .A core genome phylogenetic tree based on concatenated sequences of core genes was constructed as described previously . Prokka The metabolic and physiological properties were assessed using the standardized genus-targeted set of metabolic/physiological tests as described previously , 32, 53.Acinetobacter species in GenBank  were retrieved. The assemblies, completeness, contamination, and heterogeneity of the genomes were evaluated using QUAST v5.0.2 (N50 value, <90% genome completeness, genome contamination indicated by ≥2 in CheckM, or none-zero genome heterogeneity value for individual genomes. ANI and isDDH values between each of the genomes and type strains of Acinetobacter genomes were calculated, using the fastANI v1.32 (All genome sequences labeled as T v5.0.2  and ChecT v5.0.2 . Genome NI v1.32  and genoNI v1.32 , respectNI v1.32  or ≥70.0NI v1.32 , 47 was NI v1.32  with therpoB sequences, and the whole-genome shotgun projects of strains A. tianfuensis WCHAc060012T and A. rongchengensis WCHAc060115T have been deposited at DDBJ/ENA/GenBank under accession no. MK796537, MK796539, MK805088, MK805090, RAXV00000000, and RAXT00000000 (The nearly complete 16S rRNA gene sequences, partial 00000000 .


Multiple factors influence graft rejection after kidney transplantation. Pre-operative factors affecting graft function and survival include donor and recipient characteristics such as age, gender, race, and immunologic compatibility. In addition, several peri- and post-operative parameters affect graft function and rejection, such as cold and warm ischemia times, and post-operative immunosuppressive treatment. Exposure to non-self-human leucocyte antigens (HLAs) prior to transplantation up-regulates the recipient’s immune system. A higher rate of acute rejection is observed in transplant recipients with a history of pregnancies or significant exposure to blood products because these patients have higher panel reactive antibody (PRA) levels. Identifying these risk factors will help physicians to reduce the risk of allograft rejection, thereby promoting graft survival. In the current review, we summarize the existing literature on donor- and recipient-related risk factors of graft rejection and graft loss following kidney transplantation. Kidney transplantation (KTx) is the treatment of choice for end-stage renal diseases (ESRD) . KTx impMultiple factors influence graft rejection after KTx ,3. Pre-oIn the current review, we summarize the existing literature on donor- and recipient-related risk factors of graft rejection and graft loss following KTx.Using the large Collaborative Transplant Study database, Zeier et al. showed that death-censored graft survival and five-year graft survival were significantly lower in patients receiving grafts from female donors . The ratGender compatibility between donors and recipients may influence KTx outcomes, but there is no consensus on donor-recipient gender matching in KTx. Some studies have shown that transplanting from female donors into male recipients increases the risk of early rejection, and that transplanting from male donors into female recipients increases the risk of early graft loss compared with all other gender combinations, suggesting that gender matching may improve KTx outcome.Donor age is a better predictor of KTx outcome than donor gender. Allografts from older donors have a higher risk of post-transplant complications, delayed graft function, acute rejection, and graft failure . TransplOrgans procured from living donors provide several benefits by reducing warm and cold ischemia times and the immunological characteristics can be precisely evaluated before transplantation . Living 2), and have hypertension, diabetes, nephropathies, and kidney cysts [Extended donor criteria were defined by Port et al. in 2002. However, the marginal kidney donor criteria remain unclear, despite progressive expansion of transplant waiting lists . Physiciey cysts . Pre-traey cysts ,23.African American populations are at a higher risk of suboptimal renal transplantation . AccordiA younger age of recipients is associated with an elevated risk of suboptimal allograft outcomes. The absorption, delivery, and excretion of immunosuppressive drugs is different in pediatric and adult patients, and pediatric patients have a higher relative risk of acute rejection ,26. CurrAnother important issue, which is raised to evaluate the role of recipient age on outcomes of kidney transplantation, is the adherence of the patients to post-transplant therapies. Non-adherence has serious consequences for kidney transplant recipients, including higher healthcare costs, medical problems, allograft rejection and loss, and patient mortality. A recent systematic review of the literature reported discouraging outcomes in pediatric patients, concerning the adherence after organ transplantation. Non-adherent pediatric patients, after organ transplantation are at a twofold higher risk of biopsy-proven acute rejection and hospitalization, which lead to organ loss in 80% of these patients. Estimates of non-adherence among pediatric renal transplant recipients range from 30 to 70%. On the other hand, it has been demonstrated that each 10% decrement in adherence is associated with an 8% higher hazard of graft failure and mortality . DespiteConcomitant diseases, such as infectious disease, coagulopathies, and malignancies can affect post-KTx outcomes . The leaAcute rejection rates are high from 33% to 69%) among renal re-transplant patients , and the% to 69% The ABO blood typing system is based on a group of antigens located on the erythrocyte surface. These antigens induce antibody development upon exposure to a foreign host immune system. Incompatibility with the main blood group antigens  is clinically important because of naturally circulating immunoglobulin (Ig)M and IgG antibodies. Transplantation between individuals who are not blood-group-compatible results in hyperacute rejection, and this incompatibility has traditionally been considered a contraindication to transplantation. Because of the organ shortage, pre-transplant splenectomy, plasmapheresis, and immunosuppression have been performed to overcome compatibility issues . In 2017On the other hand, paired donor exchange is a novel program that seems to provide promising outcomes, concerning the primary outcomes, especially from US. In this program, kidneys are exchanged between two or more HLA-incompatible or ABO-incompatible living donor and recipients in order to achieve better compatibility of the organs. However, ethical considerations have restricted these approaches in some countries, such as Japan. Therefore, ABO-incompatible kidney transplantation (ABOi) has been implemented in Japan, and has shown acceptable outcomes for patients with ESKD. ABOi may increase the frequency of kidney transplants and may lead to the shortening of dialysis therapy or even its avoidance . Morath Exposure to non-self HLAs increases the risk of graft rejection and early graft failure. Pre-transplantation sensitivity to HLA antigens in the recipient stimulates clonal proliferation of lymphocytes and antibodies to donor tissue . Graft sHLA tissue typing and measurement of anti-donor HLA antibody serum levels in the recipients is carried out before transplantation. HLA tissue typing determines the allocation of deceased-donor organs. HLA class I molecules  are found on nearly all nucleated cells in the body, and lymphocytes from the lymph node, blood, or spleen can be used for tissue typing. HLA class II molecules (HLA-DR or -DQ) are present on lymphocytes , APCs, and endothelial microvascular cells . HLA typKidney transplant success and graft survival were not predictable until the late 1960’s because the effects of a positive crossmatch and high PRA incidence were not fully understood. Evaluating the kidney recipient serums against a sample of unknown donor lymphocytes, showed an 80% decrease in organ survival among patients with a successful crossmatch, indicating the pre-existing antibodies to donor lymphocytes in the recipient serum. The rate of immediate graft loss was significantly higher in female patients, particularly in those with a history of pregnancy. These findings formed the basis for a novel immunological risk evaluation and patient stratification as ‘high immunological risk’. Donor-specific antibodies are identified to predict the immunological risk of rejection after transplantation. Determining the PRA reactivity is an important pre-transplantation assessment because it assesses the presence of antibodies against class I and II HLA antigens in the serum of the recipient that could be responsible for hyperacute or acute rejection . In factCurrently, clinical application of biomarkers has been developed to obtain a better therapeutic regimen with immunosuppressive agents , since tIschemia/reperfusion injury is one of the most common complications after renal transplantation. It is influenced by the warm ischemia time (WIT) and CIT. Adenosine triphosphate production is decreased in tubular cells because of oxygen deficiency after prolonged periods of ischemia, which alters enzyme activity. After reperfusion, free-oxygen radical production induces local inflammation and stimulates the complement and coagulation cascade. While preservation solutions and cold temperature maintain electrolyte balance by diminishing the rate of metabolism in the tubular cells, prolonged ischemia increases anaerobic respiration . IschemiSeveral studies have shown that prolonged CIT and WIT increases graft alloreactivity and acute graft rejection . The CITThe frequency of delayed graft function varies from 4 to 10% in living donor transplants and from 5 to 50% in deceased-donor kidney transplants. Although the association between delayed graft function and rates of rejection has not been yet clearly described by the studies, it has been suggested that early detection of patients at risk of delayed graft function will allow early post-operative hemodynamic and immunosuppressive treatment to promote graft function . T-cell-New immunosuppressive regimens are accompanied with better monitoring and desensitization strategies have been utilized to extend the donor criteria ,69. CurrInduction treatment by multiple agents such as thymoglobulin, IL-2 receptor antibody, and other antibodies can decrease the risk of cellular rejection in recipients of kidney transplantation ,75. A meOn the other hand, immunosuppressive therapies based on calcineurin inhibitors reduce the rate of acute cellular rejection, but can induce nephrotoxicity, neurotoxicity, metabolic disorders, and electrolyte disturbances ,84. A laGraft rejection and graft loss after KTx depend on multiple factors. These risk factors can be categorized into donor-related, recipient-related, donor-recipient compatibility, and peri- and post-operative factors. Female gender, early and advanced ages, deceased donors, and concomitant diseases such as hypertension and diabetes mellitus are the main donor-related risk factors for graft rejection and graft loss. In addition, prolonged CIT might be associated with a higher risk of ischemia/perfusion injury that influences long-term graft function and survival. African American KTx recipients are vulnerable to acute rejection and graft loss. Furthermore, old age, obesity, underlying disease, prolonged dialysis, and re-transplantation are the main recipient-related risk factors that increase the probability of graft loss after KTx. Identifying these risk factors helps clinicians to avoid sub-optimal organ allocation and improves the short- and long-term outcomes of KTx. Development of new biomarkers, meticulous surgical techniques, and intensive post-transplant care, together with due attention to these risk factors, might help determine the risk of graft loss, optimize graft allocation, and improve KTx outcomes.


Arterial stiffness has been investigated as part of the physiopathology of arterial hypertension since the 1970s. Its role in increasing the “pulsatile load” imposed over the Left Ventricle (LV) has been intensely studied recently and has helped in understanding the mechanisms of Atrial Fibrillation (AF) in hypertensive patients. This paper aims to review the main evidence on this issue and establish possible mechanisms involved in the development of AF in patients with arterial stiffness. A PubMed search was performed, and selected articles were searched for references focusing on this topic. In the long term, lower blood pressure levels allow for arterial wall remodeling, leading to a lower stiffness index. To this day, however, there are no available treatments that directly promote the lowering of arterial wall stiffness. Most classes of anti-hypertensive drugs ‒ with stronger evidence for beta-blockers and diuretics ‒ could be effective in reducing arterial stiffness. There is strong evidence demonstrating an association between arterial stiffness and AF. New studies focusing on arterial stiffness and pre-fibrillatory stages would strengthen this causality relation. Atrial Fibrillation (AF) is the most frequent sustained arrhythmia in clinical practice. Although its prevalence varies regionally ,2, the eAmong developing countries, AF affects around 0.5% of the population, while its prevalence is estimated to be 3% in the USA, 1.6% in Asia, 4% in Australia and New Zealand, and in Europe, it has been reported to range between 1.9% and 3.3% of the population, depending on the country , 8. HypeThe role of arterial stiffness in the pathophysiology of hypertension became a focus for research and investigation in the 1970s in France The aim of this paper is to review the role of arterial stiffness in AF development as one independent factor. The present study's objective was to explore the effects of arterial stiffness in left atrium physiology, providing a basis for the understanding of atrial arrhythmias related to hypertension, especially AF.The authors performed a non-systematic comprehensive review of arterial stiffness in patients with AF. A literature search was conducted using the databases PubMed, applying the search terms “Arterial Stiffness and Atrial Arrhythmia” and “Arterial Stiffness and Atrial Fibrillation.” Additionally, reference lists from the available articles were further checked. The studies selected were, for the most part, clinical studies with an observational design. At the same time, articles that were not accessible or only available as an abstract or in a language other than German, English, French, or Spanish were excluded.Arterial stiffness is estimated from the aortic or Carotid-Femoral Pulse Wave Velocity (CFPWV), considered the gold-standard method. It is recognized as an independent predictor for future cardiovascular events and all-cause mortality ,17. A 1 As patients age , there is a loss of elasticity in the arteries, caused by the substitution of elastin fibers by collagen, which is less elastic, and these changes are associated with the reorganization of cell elements within the vascular wall. The result is a blood vessel less capable of expanding itself to transmit the wave created in the systole during the opening of the aortic valve PWV measurement is performed by the simultaneous positioning of two mechanographic sensors over the carotid and femoral arteries, located at a known distance. These sensors contain membranes that are successively deformed by the pulse wave shock, and this deformation is initially transformed into an electric signal which is then transmitted to a computer-based calculation program, as shown in Early vascular aging, that is, the increase of arterial stiffness at younger ages, is a strong predictor of cardiovascular outcomes.Collectively, most studies with ethnic analysis on arterial stiffness demonstrate that populations with African (and many times Hispanic) ancestry have higher arterial stiffness than Caucasian populations, and this has been seen in individuals as young as 6 and as old as 70 years old. Elevated blood pressure frequently accompanies arterial stiffness in Black populations ,21.Higher arterial stiffness in black individuals has also been seen in healthy, normotensive people, a phenomenon indicated in studies with normotensive children ,23,24 anIn spite of this, studies reveal only modest evidence of genetic influence over arterial stiffness, with no differences between ethnicities Studies have demonstrated the vast interference of cardiovascular risk factors on the pathophysiology of arterial stiffness. The mechanisms by which these risk factors lead to stiffening of the great arteries were progressively deciphered For instance, in patients with primary hypertension, arterial stiffness elevates as a result of the increase in vascular wall collagen, caused by high levels of blood pressure in repeated pulses, leading to biomechanical fatigue. Furthermore, activation of the renin-angiotensin-aldosterone system also influences this process by stimulating the proliferation of smooth muscle cells in the vessels, promoting low-grade inflammation, increasing collagen production, and favoring the formation of advanced glycation end products In individuals with type 2 diabetes, the damage to the walls of great arteries may derive from the main characteristics of the disease: hyperglycemia and insulin resistance In Chronic Kidney Disease (CKD), the process occurs essentially through vascular calcifications in with this process. DpucMGP is secreted in the circulation, making it an interesting biomarker reflecting the vascular disponibility of vitamin K The Matrix Gla Protein (MGP) signaling pathway, in particular, contributes to the process of calcification and arterial stiffness. MGP is a small secretory protein produced by chondrocytes and vascular smooth muscle cells An increase in dpucMGP circulation is independently associated with an increase in arterial stiffness in many populations, including the general population ,40 and aThis biological process does not affect every individual equally. Evidence in animal and human beings suggest that different segments of the aortic wall are affected heterogeneously ,46. FactIncreased arterial stiffness is frequently found in ethnic groups of lower socioeconomic status that have limited access to healthcare, inadequate diet, and unhealthy lifestyle Elevated arterial stiffness makes the transmitted pulse wave return from the terminal organs earlier, before the systole ends, increasing the pressure load over the left ventricle. Given the fact that different organs have different degrees of arterial pressure, consistent with the distance from the aorta and the anatomy of the vascular tree, registers of these waveforms vary according to the analyzed site A sub-analysis of the MESA Study demonstrated that Pulse Pressure (PP), but not median arterial pressure, was associated with a higher incidence of AF, even when adjusting for left atrium diameter and left ventricle mass index. An association between arterial stiffness and new AF episode has also been seen, even when adjusting for hypertension. Elevated “pulsatile load” ‒ that translates into elevated arterial stiffness ‒ would lead to left atrium distension and consequently neurohormonal activation leading to an inflammatory response, contributing to the development of AF Chen et al. showed that patients with isolated AF , had a higher CFPWV, suggesting that early structural and functional changes in the arteries could be implicated in the pathogenesis of AF in these individuals In a population of 4264 Japanese individuals, Cui et al. identified an association between arterial stiffness  and new episodes of AF Yoshida et al. demonstrated for the first time, in a cohort of 1156 individuals, that arterial stiffness has a negative impact on left atrium function, assessed through transthoracic echocardiogram strain. The identified associations were independent of left ventricle volume and function, as well as BNP levels In echocardiography, left atrium peak systolic strain has been studied mainly in AF, where it was shown to be a factor for prognosis ,58. ShaiAdditionally, a meta-analysis by Ma et al., with 686 total patients, showed that patients with recurrent AF after catheter ablation had higher values of left atrium peak systolic strain when compared to those that did not present recurrence. Finally, Parwani et al. demonstrated that reduced left atrium peak systolic strain (< 10%) was the most important factor associated with AF recurrence More recently, in a Korean cross-sectional study with 8048 individuals, Chung et al. found that an increased arterial stiffness (assessed by the Cardiothoracic Vascular Index ‒ CAVI) is significantly associated with a higher prevalence of AF among those classified as being at intermediate and high risk by the Framingham Score to lowering the blood pressure through pharmacological intervention could reduce the risk for AF. In the same study, interestingly, this last association was only significant for variants related to beta-blockers and calcium channel blockers target proteins Regarding hypertensive individuals in general, a recent study by Hyman et al. demonstrated, through Mendelian randomization, that genetic variants related to increased arterial pressure were associated with a higher risk of AF, consistent with a causal relationship. These data support the concept that The difference in effect size may also be due to the pleiotropic effects of these particular anti-hypertensive medications, as β-receptor signaling and calcium handling have both been implicated in AF initiation and arrhythmogenesis independent of blood pressure In another mendelian randomization study that assessed polymorphisms associated with increased arterial stiffness, it was shown that a genetic predisposition for a higher arterial stiffness index was unidirectionally associated with an increase in incidence risk and prevalence of AF. These results are consistent with a causality association between arterial stiffness and AF A similar study by Georgipoulos et al. presented the same causality relation between hypertension and atrial fibrillation, in which a 1 mm. Hg increase in systolic blood pressure increased the relative risk of AF development by 1.8%. For diastolic blood pressure and pulse pressure, this increase was 2.6% and 1.4%, respectively These data support the hypothesis of causality between arterial stiffness, hypertension, and atrial arrhythmias.At this moment, there are no available drugs that directly promote arterial stiffness lowering. Nonetheless, most classes of anti-hypertensive drugs ‒ with most evidence for beta-blockers and diuretics, may be effective in reducing arterial stiffness. Among many patients with hypertension, an immediate decline in arterial stiffness may occur with anti-hypertensive therapy due to the reduction of the circumferential stress in the vessel.In the long term, lower pressure levels allow for arterial wall remodeling, leading to lower stiffness. However, it cannot be assumed that anti-hypertensive therapy always improves arterial stiffness. The first randomized clinical trial to determine whether normalization of aortic stiffness improves cardiovascular outcomes, the SPARTE Trial, was recently published, showing no benefit in reducing cardiovascular events when guiding the treatment of hypertension by PWV when compared to the standard strategy by current guidelines, although there was a greater reduction in PWV in the group that guided the treatment by this parameter. It is important to emphasize that the work did not reach statistical power Many therapeutic strategies have been successful in animal models, including allopurinol and nitric oxide stimulants ‒ like nitrates, renin-angiotensin-aldosterone blockers ‒ such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone receptor blockers (spironolactone). Although commonly prescribed in clinical practice for the treatment of hypertension and HF, they are not approved specifically for the reduction of arterial stiffness ,66.Exercise has also been demonstrated to have a positive modulator effect over arterial stiffness. A cross-sectional study showed an inverse relationship between exercise and stiffness, even with low-intensity physical activity. On the other hand, a sedentary lifestyle was associated with higher systolic blood pressure and PWV Other proposed therapies include the use of Dipeptidyl-Peptidase 4 (DPP4) inhibitors ,67 and SA knowledge gap that is still to be clarified is whether a reduction in arterial stiffness leads to a decrease in the burden of atrial arrhythmias, from frequent atrial ectopies to AF. Another knowledge gap is whether there is an association between arterial stiffness and stages considered to be pre-fibrillatory that, once identified, would help in the understanding of this process.There is much evidence in the literature from different designs of observational studies indicating an association between arterial stiffness and atrial fibrillation. New studies exploring the association between arterial stiffness and pre-fibrillatory stages, and therefore, early stages of AF, would help corroborate the causality relationship between these two conditions.Although much has been discovered since the first studies that related arterial stiffness to the progression of cardiovascular disease, the ability to clinically interrupt or revert the stiffness demands a much deeper understanding of the molecular, cellular and matrix interactions involved in this process.Lage JGB - Conceptualization, - Data curation, - Formal analysis, Resources AND Writing - review & editing. Bortolotto LA - Conceptualization, - Data curation. Bortolotto AL - Data curation, Writing review and editing. Scanavacca MI - Supervision, - Validation, - Visualization Darrieux FCC - Supervision, - Validation, - Visualization Anyway.The authors declare no conflicts of interest.


Dr. Praveen Kerala Varmaemail: varmapk@gmail.com; praveenv21204@aims.amirta.eduDr. Rajesh Joseemail: rajeshj21304@aims.amirta.eduFollowing publication of the original article , the autThe author group has been updated above and the original article  has beenAuthors' contributionsJJ: developed the graft in Amrita, did lab-based work in Bristol, analyzed data and drafted the manuscript; VDB: assisted animal surgery in Bristol and undertook vascular doppler; NS: helped with lab-based work in Bristol and the bioreactor; AW: helped with graft engraftment lab-based work in Bristol; TJ: undertook the ex-vivo optical coherence tomography on explanted grafts in Bristol; HMB: undertook mechanical strength work at Amrita and prepared Fig. 2a, 4a, and graphical abstract; PKV: helped developing the graft in Amrita before studies in Bristol; RJ: helped developing the graft in Amrita before studies in Bristol; SK: helped developing the graft in Amrita and securing previous funding from the Indian Government; DM: helped with developing the graft in Amrita including supervising the Amrita-based bench testing and related interpretation, co-secured the funding for the Commonwealth Scholarship Commission for the Split-site scholarship, co-drafted the manuscript; SJG: supervised the lab-based histology work in Bristol related to graft characterization and interpretation, co-secured the funding for the Commonwealth Scholarship Commission for the Split-site scholarship, co-drafted the manuscript; RA: acted as senior author, conceived and led all the bioreactor and in-vivo work done in Bristol and related interpretation, secured all funding to support bioreactor and in-vivo work in Bristol, co-drafted the manuscript and was corresponding author. All the authors have read and approved the final manuscript.


RRM2B plays a crucial role in DNA replication, repair and oxidative stress. While germline RRM2B mutations have been implicated in mitochondrial disorders, its relevance to cancer has not been established. Here, using TCGA studies, we investigated RRM2B alterations in cancer. We found that RRM2B is highly amplified in multiple tumor types, particularly in MYC-amplified tumors, and is associated with increased RRM2B mRNA expression. We also observed that the chromosomal region 8q22.3–8q24, is amplified in multiple tumors, and includes RRM2B, MYC along with several other cancer-associated genes. An analysis of genes within this 8q-amplicon showed that cancers that have both RRM2B-amplified along with MYC have a distinct pattern of amplification compared to cancers that are unaltered or those that have amplifications in RRM2B or MYC only. Investigation of curated biological interactions revealed that gene products of the amplified 8q22.3–8q24 region have important roles in DNA repair, DNA damage response, oxygen sensing, and apoptosis pathways and interact functionally. Notably, RRM2B-amplified cancers are characterized by mutation signatures of defective DNA repair and oxidative stress, and at least RRM2B-amplified breast cancers are associated with poor clinical outcome. These data suggest alterations in RR2MB and possibly the interacting 8q-proteins could have a profound effect on regulatory pathways such as DNA repair and cellular survival, highlighting therapeutic opportunities in these cancers. RRM2B encodes a small subunit of p53-inducible ribonucleotide reductase (RNR). The RNR is a heterotetrametric enzyme responsible for the de novo conversion of ribonucleotide diphosphates into the corresponding deoxyribonucleotide diphosphates for DNA synthesis, thus playing an important role in maintaining deoxyribonucleotide pools , with distinct but variable clinical phenotype  (amplifications and deletions) have decreased overall survival (OS)  . Similark cancer , esophagk cancer  and lungk cancer . Anotherl cancer .RRM2B amplification may be driven by selection of RRM2B function, or RRM2B may be amplified as a passenger, concurrent with selection for a nearby gene with a driver activity in cancer. In breast cancer, multiple genes localized in the 8q12.1–8q24.23 interval were found to be amplified, including RRM2B , but also exhibit distinct mutation signatures. Analysis of the most common breast cancer subtype indicated that RRM2B amplifications may independently impact clinical outcomes in these cancers. Further, tumors bearing RRM2B amplifications showed that several genes in the 8q22–8q24 region  are highly amplified. Additionally, analysis of 8q-proteins suggests functional interaction within the same cell regulatory mechanisms of DNA damage response and repair, hypoxia and apoptosis. Based on these results, we hypothesize that while MYC may be the cancer driver, co-amplification of RRM2B and other 8q-genes may be relevant for cancer cell survival. These finding suggest opportunities for novel therapeutic targeting strategies (such as those targeting DNA damage response and repair) for tumors carrying RRM2B alterations.Here, using data from TCGA, we found that 2 . The truncating mutations in TCGA are frameshift deletions, frameshift insertions, nonsense, splice site. All mutations were analyzed for co-occurrence, including those that were homozygous or heterozygous.TCGA studies were accessed using the cBioPortal website2 . Data waRRM2B there was only a single case of deep deletion out of all , observed in BRCA, and was removed. For CCNE2, EI3FE, MTDH, MYC, RAD21, TP53INP1, and YWHAZ—there were no cases of deep deletion for any of the genes in the HNSC study, but there was one case each in EI3FE, RAD21 and YWHAZ with deep deletions in the BRCA study, and also one case each in EI3FE and MTDH as well as two cases in RAD21 for the OV study. V2 RSEM from cases with different copy number variants categories and statistical significance was tested in Graphpad Prism 8.0 using Mann-Whitney Non-Parametric T-test , BRCA (breast cancer study) and HNSC (head and neck cancer study) studies on 11/7/2018, and 3/19/2020. The RNA seq. data were only analyzed for tumors that were also profiled for copy number variants. Cases were segregated based on copy number variants type: deep deletion, shallow deletion, diploid, gain and amplification. For c T-test . Additioc T-test  and log c T-test  p-values3 on 11/5/2018. Next, IDs of subjects with different cancer types were downloaded from the cBioPortal website2, and subjects with amplification in RRM2B and MYC genes were selected. Presence or absence of these amplifications classified the subjects into four categories: (1) cases with amplification in both RRM2B and MYC, (2) cases with amplification in RRM2B, but not in MYC, (3) cases with amplification in MYC, but not in RRM2B, (4) and cases without amplification in both genes. For each specific cancer type, mutational spectra of each category were calculated by finding the average number of amplifications in each of the 96 mutation classes. To compare differences in these 96 mutation types, one-way ANOVA  cases with amplification in RRM2B, but not in MYC, (3) cases with amplification in MYC, but not in RRM2B, (4) and cases without amplification in both genes, and anova1, anova2 and Wilcoxon rank-sum functions in MATLAB R2018a were used to test for significance. Each signature type was determined to be significant only if its P-value was below 0.05 in the one-way ANOVA test. The two-way ANOVA was used to distinguish the impact of factors such as co-amplifications with MYC. Additionally, the Wilcoxon rank-sum test was also performed as a secondary method to test for significance.Tumor whole-exome sequence data in the TCGA Pan-Cancer Atlas studies , that includes spectra of individual tumors, was downloaded from the Synapse platformay ANOVA , two-wayay ANOVA , and Wilay ANOVA  were useay ANOVA  was applRRM2B or MYC, in both or neither. The clinical data from each group were used to generate OS and disease/progression-free survival (DFS) Kaplan-Meier curves  TCGA study. Patients were divided into different groups based on having amplifications in r curves  using Grr curves  and signlso used , and sigcbioportal.org. The genes used for analysis are located on chromosome 8 from the region 8q11.2–8q24.3 and have been associated with cancer according to the Cancer Index4. The amplification pattern of other 8q-genes in BC, OC, and HNSCC was compared to cases with co-amplifications of MYC and RRM2B, cases with single amplifications or cases that were unaltered. A univariate analysis was conducted to calculate the positive or negative linear trend for the frequency of gene amplification, assessed at 95% confidence interval. The Pearson correlation coefficient and p-values were computed by using PROC CORR in SAS 9.4. The significance level was set at p < 0.05.The tumors that were assessed for alteration frequency were also analyzed for amplifications in the 8q-genes. Tumor data was downloaded on 6/22/18 from p-values, and FDR thresholds at 0.01.Data for the RRM2B interaction network was downloaded from the BioGRID database  10/25/2. SeveralRRM2B is frequently amplified, with the highest percentage observed in ovarian, breast, bladder, and liver cancers (21.54–14.5%), and a lower rate of amplifications in multiple other cancers (14–0.6%) (RRM2B were only observed in Non-Hodgkin’s lymphoma (∼2%). In addition to amplifications, a low frequency of mutations (<2%) were observed in head and neck, lung, endometrial, esophagogastric, cervical, and pancreatic cancers  . Deletio cancers . Mapping/regions , unlike /regions . Only th/regions . This muMYC  did not have RRM2B amplifications  and head and neck squamous cell carcinoma (HNSCC), this was half of all cases with MYC amplifications, while in breast cancer (BC) this was ∼90% cases   .RRM2B and/or MYC were amplified as part of an amplicon with multiple other 8q-genes  and MYC (8q24.21). This amplicon contains 11 cancer relevant genes: BALC, ANGPT1, EIF3E, EBAG9, TRSP1, RAD21, EXT1, TNFRSF11B, NOV, HAS2, and RNF139 . The strongest correlations were observed for skin , pancreatic adenocarcinoma , ovarian cancer , liver hepatocellular carcinoma , and esophageal cancer  . Finally, we also observed that mRNA expression of multiple genes in the amplicon was also significantly increased  . All othncreased .RRM2B, MYC, and several other 8q-amplicon genes was increased, we next tested if the products of these genes within the 8q-amplicon interact with RRM2B. Since the expression of RRM2B amplifications are associated with specific tumor mutational signatures. For this analysis, we used the recent PanCancer Atlas data, reporting mutational spectra for 9493 individual tumors, including 926 BC, 384 OC, and 461 HNSCC and 524 LUAD . Additionally, RRM2B amplification cases tend to have worse DFS than MYC only cases (p = 0.0519).Based on the distinct tumor signatures observed in  cancers , we nextobserved , which iobserved . Howeverobserved . MYC ampRRM2B amplifications separately in each of the three major subtypes of breast cancer . We observed that patients with ER + PR + HER2 + BC bearing RRM2B amplifications had a significant decrease in OS  had significantly worse OS than ER- PR- HER2- patients (n = 26) (p = 0.0426). The previous studies that observed worse OS in BC, based on RRM2B amplification, did not consider subtype differences, and may have only included the major BC subtype (ER + PR + HER2 +). Additionally, p-values for all comparisons (log-rank test and Gehan-Breslow-Wilcoxon test) in all the above BCs are available in To further explore the conflicting findings in BC, we analyzed 2 + n = 8, ER + PRRRM2B, which is a major downstream target of p53, is highly amplified across multiple tumor types. Frequent RRM2B amplifications are a contrast to TP53 loss of function mutations or deletions that are typically found in tumors. We found that RRM2B, which is present on chromosome 8, is usually co-amplified with MYC oncogene . We also found, in multiple cancers, that tumors with co-amplified RRM2B and MYC exhibit significant amplification of the 8q22.3–8q24 region of chromosome 8. Intriguingly, we observed that several genes within the 8q-amplicon also interact with the RRM2B-functional network. Pathway enrichment analysis suggests the importance of 8q-region genes in response to oxygen levels, DNA replication, cell cycle, and DNA damage response.This study demonstrates that CDKN1A, GADD45, MDM2  a larger sample size of RRM2B-only amplified tumors and more balanced number of samples across each category, (b) analysis of outcomes in other cancers, and (c) other independent prognostic factors of overall survival. A previous study in breast cancer found frequent MYC co-amplifications with multiple genes in the 8q chromosomal region , and oxidative DNA damage. A previous study in mice found that overexpression of RRM genes combined with defective mismatch repair can lead to mutagenesis, and carcinogenesis (RRM2B overexpression on the levels of reactive oxygen species is not known. The observation of mutation signatures associated with increased reactive oxygen species suggests that RRM2B overexpression may impede the oxidative stress or oxygen sensing pathway. Finally, these observed mutation signatures suggest therapies that target defective DNA repair, such as PARP inhibitor therapy, may lead to clinical benefit in patients with RRM2B-amplified tumors (Mutation signature analysis revealed that ogenesis . While aogenesis , the impd tumors .in silico analysis of RRM2B alterations in cancer and their potential significance. Further studies in cellular models are warranted to delineate the role of RRM2B, and other 8q-chromosome genes in cancer cell maintenance, therapeutic targeting and clinical outcomes.Alterations in genes involved in DNA replication and/or repair, and DNA damage response pathways are known to increase genetic instability, and lead to cancer . RRM2B iRRM2B alterations in multiple tumor types, majorly reflected as RRM2B amplifications in conjunction with MYC, and other genes on chromosome 8. These cases exhibit a distinct 8q-amplification pattern as well as survival outcome differences and mutation signature differences, depending on cancer type and subtypes. Future genome-wide studies of other cancer datasets are warranted to confirm the results of the present study. Finally, studies in cellular models are required to delineate the role of RRM2B, and other 8q-chromosome genes in cancer cell maintenance, therapeutic targeting and clinical outcomes.Overall, this study provides an in-depth analysis of www.cbioportal.org.Publicly available datasets were analyzed in this study. This data can be found here: WI and ED: methodology, formal analysis, investigation, roles, writing—original draft, data curation, visualization, and validation. SS: formal analysis, investigation, roles, writing—original draft, and data curation. TV: software, formal analysis, and data curation, and visualization. GR: writing—review and editing, methodology, supervision, and funding acquisition. SA: conceptualization, methodology, writing—review and editing, supervision, project administration, resources, and funding acquisition. All authors contributed to the article and approved the submitted version.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.


Rapid development of advanced gastrointestinal endoscopic techniques contributed to the appearance of new biomedical materials including polymers, which are used for the production of different types of endoprostheses. Endotherapy (ET) of postinflammatory pancreatic and peripancreatic fluid collections (PPFCs) with the use of lumen-apposing metal stent (LAMS) is an effective method of treatment. This paper describes the high efficacy of ET and its potential complications, which are mostly related to the design of the LAMS used. The high efficacy of LAMS in the transmural drainage of PPFCs is associated with lower safety of treatment. Complications of ET presented in the manuscript are mainly related to endoprosthesis' construction. This paper presents possible directions of development in the field of transmural LAMSs, which in the future may contribute to the invention of an innovative type of LAMS based on new biomedical technologies. Possibly, subsequent novel endoprosthesis projects, based on the above results, will be able to meet the current needs and requirements associated with endoscopic transmural drainage procedures in cases of postinflammatory PPFCs. The ultimate goal is to improve safety of minimally invasive techniques for treatment of the local consequences of pancreatitis. Acute pancreatitis (AP) of moderate and severe clinical course is associated with high risk of local complications and organ failure leading to increased mortality –4. PancrEndoscopic transmural drainage consists in creating a fistula between the lumen of the PPFC and gastrointestinal tract to allow for outflow of the content from the PPFC into the gastrointestinal tract , 15, 16.Development of advanced endoscopic techniques has led to rapid advancements in biomedical materials, including polymers for manufacturing endotherapeutic devices. Currently, there is a wide variety of transmural endoprostheses of different sizes, shapes, and designs for endoscopic treatment of postinflammatory PPFCs . These eHowever, the role of LAMSs in transmural drainage remains unclear , 17–23. In addition, the authors present an endoscopist's input regarding an ideal transmural endoprosthesis to improve the outcomes of endotherapy in postinflammatory PPFCs.Prospective analysis of treatment outcomes in patients with postinflammatory PPFCs in late phase (>4 weeks) of pancreatitis, who received endoscopic treatment at the Department of General, Gastroenterological, and Oncological Surgery, Ludwik Rydygier Collegium Medicum, in Bydgoszcz, Nicolaus Copernicus University, in Toruń from 2018 to 2021.The study was approved by the Ethics Committee at the Collegium Medicum of the Nicolaus Copernicus University and was conducted in accordance with the Declaration of Helsinki. All patients provided informed consent for endoscopic procedures.The diagnosis of pancreatitis, the criteria of clinical and morphological categorization, and all the definitions of local and systemic complications were based on the 2012 revised Atlanta classification . The staAll patients with clinical symptoms of PPFCs due to acute or chronic pancreatitis were enrolled. The patients underwent endoscopic drainage procedures. Qualification for endoscopic treatment was based on the clinical picture and imaging results, primarily abdominal contrast-enhanced computed tomography (CECT). The start of endoscopic treatment was postponed until the collection became encysted at the latest. If it was necrotic, the necrotic material collected within the cavity became liquified and a WOPN was formed, which occurred four weeks from the onset of the disease and was determined on the basis of imaging examinations of the abdominal cavity.Patients with PPFCs that were not a consequence of pancreatic inflammatory disease were excluded from the study. The study also excluded patients with postinflammatory PPFCs without clinical symptoms and those who had undergone surgery in the pancreatic region. Patients who had undergone interventional treatment in the early phase (<4 weeks) of AP were also excluded.In patients with symptomatic PPFCs in the late phase of pancreatitis, transmural drainage using the single transluminal gateway technique (SGT) was performed if endoscopic ultrasound revealed that the distance between the wall of the collection and the gastrointestinal wall did not exceed 30 mm. In patients with sterile pancreatic pseudocysts, the method of choice was passive transmural drainage. In patients with infected pancreatic pseudocysts or WOPN (both sterile and infected), the method of intervention was active transmural drainage.In the event that drainage with the single transluminal gateway technique (SGT) was ineffective and the fluid collection spreads beyond the lesser sac, multiple transluminal gateway technique (MTGT) was used. This technique has also been used in cases of multilocular postinflammatory PPFCs. If the necrotic areas were infected or transmural drainage was unsuccessful for WOPN patients, direct endoscopic necrosectomy was performed.If endoscopic techniques with transmural access were ineffective, additional access to the collection cavity was created using percutaneous drainage  or transpapillary drainage . Endoscopic retrograde pancreatography (ERP) revealed communication between the main pancreatic duct (MPD) and the PPFC cavity.Endoscopic procedures were performed under general anesthesia with tracheal intubation. All patients provided informed consent for this procedure. All were performed by a single endoscopist, and the procedure entailed carbon dioxide insufflation and use of a linear echoendoscope , duodenoscope , and gastroscope . Before the procedure, all patients received prophylactic antibiotic treatment (ciprofloxacin or ceftriaxone). Samples of the material contained in the PPFC were collected for microbiological, cytological, and laboratory analyses.Placement of the pancreaticogastric or pancreaticoduodenal anastomosis in the form of transmural cystostomy was performed under EUS guidance. The anastomosis between the gastrointestinal lumen and the collection cavity was created with a 10 Fr cystotome  and then dilated with a high-pressure balloon with a diameter of up to 15 mm (Cook Endoscopy or Boston Scientific). Through the stomy, a transmural metal endoprosthesis (LAMS) was inserted, measuring 16 mm in diameter and 20 mm, 30 mm, or 40 mm in length  Figures  and 8. FIn patients with additional transmural stomy created between the collection and lumen of the gastrointestinal tract, the placement of the anastomosis was also decided under EUS guidance. The transmural cystostomy was created with a 10 Fr cystostome  and expanded with a high-pressure balloon with a diameter of up to 15 mm . Next, a metal endoprosthesis (LAMS) with a diameter of 16 mm and length of 30 mm or 40 mm  was inserted transmurally. Depending on the type of drainage, a 7 Fr or 8.5 Fr nasal (Wilson-Cook) and/or 7 Fr or 8 Fr double-pigtail stent (Wilson Cook) drain was inserted through the endoprosthesis and into the collection lumen.Direct endoscopic necrosectomy procedures, which mechanically remove necrotic tissue, were performed in WOPN patients with no clinical improvement despite the drainage treatment or even if the necrotic collections became infected. The first stage of DEN involved removing the nasal drain. Through the transmural stomy with the LAMS inside, a gastroscope was introduced into the necrotic area. The necrotic collection cavity was subsequently flushed multiple times with saline solution, and the washings were removed by suction. A 15–20 mm extraction balloon (Cook Endoscopy) and Dormia basket (Cook Endoscopy or Olympus) were used to remove necrotic tissue under direct endoscopic image guidance. This procedure was repeated several times. Upon completion, the nasal drain and/or double pigtail plastic stents were reinserted transmurally.When active transmural drainage was used, the PPFC was flushed with saline (60–200 mL) through the nasal drain every 2 hours during the first 48 hours of the postoperative period and every 4 to 6 hours on the following days. If the patient's clinical symptoms suggested PPFC infection, the antibiotic therapy was prolonged or the contents of the collection were cultured again with antibiotic susceptibility testing.During active transmural drainage, the size of the fluid collection was measured every seven days via abdominal ultrasound. Abdominal CECT was used to confirm complete regression of the fluid collection or in cases where the patient's clinical condition deteriorated despite ongoing treatment. Active drainage was discontinued once clinical success could be established, while the patients were still on passive transmural drainage. After four weeks, an endoscopic procedure was performed during subsequent hospitalization and the passive transmural drainage was either continued  or discontinued . The decision to continue passive transmural drainage was made depending on the fluid collection size and the presence of any disruption in the MPD, as revealed during ERP. If the PPFC persisted in residual form (–30–40 mm) or recurred (>40 mm), passive endoscopic drainage was continued and the transmural endoprostheses were replaced for another four weeks. In cases of complete PPFC regression, an endoscopic procedure was performed to remove the transmural endoprostheses and passive endoscopic drainage was completed.Technical success was defined as successful placement under endoscopic and radiologic image guidance of the transmural stent with its distal and proximal ends located in the PPFC cavity and lumen of the gastrointestinal tract (stomach or duodenum), respectively. A procedure was confirmed to be technically successful if the contrast agent administered was flowing freely from the PPFC through the transmural stent without leaking out of the gastrointestinal tract or the stent.Clinical success was defined as resolution of complaints associated with the presence of the PPFC and complete regression of the collection or its diameter decreasing to <40 mm in imaging tests.Long-term success was defined as the absence of complaints and complete PPFC regression or its size decreasing to <40 mm during follow-up after the end of the endoscopic drainage.Recurrence of fluid collection was understood as a collection size of >40 mm or reappearance of symptoms during follow-up.Transmural stent dislocation was defined as the spontaneous migration of the transmural stent away from the anastomosis between the gastrointestinal lumen and PPFC cavity.Early dislocation of the transmural stent was established if dislocation occurred within the first seven days following the procedure of endoscopic transmural drainage.Late dislocation of the transmural stent was established if dislocation occurred more than seven days after the procedure.Proximal stent dislocation was defined as migration of the transmural endoprosthesis from the anastomosis into PPFC lumen, where both flanges of the stent were inside the collection cavity and away from the gastrointestinal wall.Distal stent dislocation was defined as migration of the transmural endoprosthesis from the anastomosis into the lumen of the gastrointestinal tract, where both flanges of the stent were inside the gastrointestinal lumen.http://statistica.io). Quantitative variables are characterized using arithmetic means, standard deviation, median, and minimum and maximum values (range). Qualitative variables are presented as numbers and percentages.All statistical calculations were conducted using the statistical software TIBCO Software Inc. (2017). Statistica software , version 13, was also used  years) were diagnosed with WOPN and 69  years) with pancreatic pseudocysts. The mean time from the onset of pancreatitis to the start of endotherapy (ET) was 76 (29–411) days. Chronic pancreatitis was diagnosed in 72 patients (28.02%). Detailed patient characteristics are presented in Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Staphylococcus epidermidis. The remaining indications for endoscopic treatment are shown in An infection diagnosed on the basis of a positive culture of the PPFC contents was present in 115 patients with WOPN and in 42 patients with pancreatic pseudocysts. In both groups, the most common bacterial pathogens isolated from the fluid sample were All 257 patients underwent endoscopic transmural drainage of postinflammatory PPFCs . Twenty-seven patients with sterile pancreatic pseudocysts underwent passive transmural drainage initially. Active transmural drainage was performed in 230 patients (188 patients with WOPN and 42 patients with infected pancreatic pseudocysts). Additional active transpapillary drainage was performed in 11 patients  and an aSingle transluminal gateway techniques Figures  were appActive endoscopic drainage took an average of 13.34 (5–82) days. The average duration of passive transmural drainage was 84 (25–281) days. The mean number of endoscopic procedures was 8.61 (2–28). During the endoscopic treatment of the 257 patients with PPFCs, 942 LAMS were used.Complications during endoscopic transmural drainage were observed in 34 patients (13.23%). Of these, a vast majority were stent-related complications, constituting 32 of the complicated cases. Among the 34 patients who experienced endotherapy complications, 8 required surgical treatment. Detailed information on the complications is presented in The most common complication of endoscopic treatment was bleeding into the upper gastrointestinal tract, which was observed in 20 patients. For all cases, the cause was bleeding from the PPFC through transmural cystostomy into the gastrointestinal lumen .Hemospray, Cook Endoscopy) sprayed into the collection cavity was effective for managing bleeding in 5 patients. Another 5 patients required endovascular treatment with embolization of the perforated vessel (4 cases) or insertion of a stent graft to bypass the site of vascular rupture (1 case)  drainage was used to treat the pancreatic fluid collection. Among the 5 patients who underwent surgical treatment for early transmural stent dislocation, 3 required a laparotomy Figures  and 2 unPPFC perforation with fluid leakage from the collection cavity into the retroperitoneal space was found in 2 patients. One of these patients required surgical treatment; laparotomy was performed with drainage and rinsing of the retroperitoneum. The other patient underwent successful percutaneous drainage of the retroperitoneal space without the need to resort to surgical treatment.Five of the 34 complicated cases developed late dislocation of the transmural stent. Two of these patients were diagnosed with distal dislocation of the stent into the gastrointestinal lumen. The remaining three patients had proximal dislocation of the transmural stent into the collection cavity. The average time from the procedure to the diagnosis of late dislocation was 17 (10–27) days. In all dislocation cases, an endoscopic procedure was performed wherein the dislodged stent was grasped with rat tooth forceps and pulled outside Figures .Technical success of the transmural drainage procedure was achieved in 255 patients (99.22%). Clinical success was achieved in 242 patients (94.16%).Mortality during ET was observed in 8 patients (3.11%) and was not associated with ongoing endoscopic treatment. All fatal cases reported were caused by multiple organ failure during the course of severe acute necrotizing pancreatitis.During the follow-up period, which lasted an average of 213 (32–1034) days, long-term success of PPFC ET was achieved in 221 patients (85.99%). PPFC recurrence was reported in 17 patients during follow-up. Of these, 15 patients underwent successful endoscopic treatment for recurrent fluid collection. In two patients, the recurrent PPFC necessitated surgical treatment.The choice of drainage technique in patients with postinflammatory PPFCs should rely primarily on experience of the treating medical center , 26–33. Traditionally, endoscopic transmural drainage of postinflammatory PPFCs has been performed using plastic (teflon or polyethylene) double-pigtail stents , 15–18. As a result of advancements in biomedical materials, SEMSs were introduced to the market , 34–41. With this, only the fully covered type can find application in transmural drainage of postinflammatory PPFCs, where the SEMS must be removed upon treatment completion , 19–23. The two most common and most serious groups of complications associated with the endoscopic treatment of PPFCs are gastrointestinal bleeding  and perfWith regard to gastrointestinal bleeding during transmural drainage of postinflammatory PPFCs, great progress in reducing the incidence of complications has been achieved with the advent of EUS techniques , 17. EUSThe application of new polymers in manufacturing transmural stents in the form of additional layers of coating to the distal flange of the LAMS will most certainly limit the risk of PPFC cavity bleeding during transmural drainage procedures. This will make it less likely for the distal flange of the LAMS to injure the back wall of the PPFC, and it will no longer be necessary to insert a plastic double-pigtail stent through the lumen of the LAMS. The thick polymer coating of the most protruding part of the distal flange will then take over the function hitherto performed by the additional plastic stent, which can lower the costs of endoscopic treatment of PPFCs.Another major complication of transmural drainage with LAMS is gastrointestinal tract perforation due to transmural stent dislocation that migrates outside of the transmural anastomosis –45. GastTreating transmural stent dislocation should primarily depend on the patient's clinical condition. In stable patients with an early transmural stent dislocation and air leaking out of the gastrointestinal lumen, as revealed by imaging, endoscopic treatment can be attempted to adjust the position of the dislodged stent or add another stent using the stent-in-stent technique. If this strategy is successful, it is also necessary to remove air from the peritoneal cavity through a percutaneous incision. Endoscopic treatment of early dislocations of LAMS, despite favorable short-term outcomes, usually prove ineffective on long-term follow-up, thus leaving surgical treatment as the method of choice. This paper describes an effective method of surgical treatment for early dislocation of the LAMS, consisting of suturing the perforated site  within the upper gastrointestinal tract and removing the dislodged transmural stent through laparotomy or, preferably, through laparoscopic access. The surgery also involves percutaneous drainage  of the PPFC. Subsequently, in the postoperative period, while the external drainage is still ongoing, an endoscopic procedure is performed, whereby internal drainage  of the PPFC is provided. Upon internal drainage completion, the external drainage was removed. This is how external drainage is replaced with the PPFC internal drainage.In cases of late transmural stent dislocation occurring more than a week after the procedure, endotherapy is generally an effective method of treatment. Proximal stent migration occurs when the transmural stent migrates into the PPFC lumen. Endoscopic treatment of late proximal dislocation of the transmural stent involves inserting another transmural stent through the transmural cystostomy or creating another cystostomy between the gastrointestinal lumen and the PPFC cavity. Through the transmural endoprosthesis, an endoscope is inserted into the PPFC under the guidance of endoscopic imaging. Different types of endoscopic tools are used to capture and remove the dislodged stent. In cases of late distal dislocation of the transmural LAMS where the stent migrates into the gastrointestinal lumen and if the dislodged stent is located within the upper gastrointestinal tract, it can still be removed with the use of endoscopic techniques. However, if the dislodged stent has migrated further down the gastrointestinal tract and beyond the duodenojejunal flexure (ligament of Treitz), the patient is usually monitored until the stent is spontaneously passed along the entire gastrointestinal tract without any complications. If these strategies fail, surgical treatment remains the method of choice.As one follows the continuous dynamic development of biomedical technologies, it can be presumed that as the design of transmural stents evolves towards a larger diameter and size of both flanges and their improved shape, it will become possible to limit the risk of early and late dislocations of transmural LAMS in terms of both distal and proximal migrations. Moreover, a sufficiently larger lumen diameter of the LAMS prevents it from being obstructed by necrotic tissues.According to the guidelines for endotherapy of postinflammatory PPFCs, transmural LAMS should be either replaced or removed after 8–12 weeks , 36–41. This paper addresses the challenges and issues faced by endoscopists performing transmural drainage using LAMS. From the endoscopist's perspective, a major challenge in transmural drainage of PPFCs is often the right placement of the stent. This is a crucial stage in determining the technical success of the procedure. Once the transmural cystostomy is performed and the guidewire is inserted into the PPFC, the transmural stent is introduced. Considering the challenging anatomical conditions and rigid nature of the stent delivery system used to introduce the unexpanded LAMS, this stage requires particular caution while expanding the stent. Failure of any kind has the potential to cause early dislocation of the stent during the endoscopic procedure, which can lead to gastrointestinal perforation. At this point, this depends on the experience and skill of the endoscopist. While the construction and technical features of the stent delivery system can be expected to improve, the difficult anatomical environment will not. In particular, PPFCs are located away from the gastrointestinal wall, which do not form a discernible bulge on the gastric or duodenal wall and are situated within the distal part of the pancreatic body or within the tail, where transmural access can usually be obtained from the subcardiac region of the stomach, often with endoscopic inversion. A major convenience with regard to improving the quality and safety of endoscopic transmural drainage with LAMS is the controlled release system used in certain types of SEMS, which allows for accurate and controlled placement of the transmural stent in the desired location. This solution limits the risk of transmural stent dislocation and consequently reduces the potential for gastrointestinal perforations and leaks within the pancreaticogastric or pancreaticoduodenal anastomosis. Despite these benefits, controlled release systems have not yet been featured in LAMS for transmural drainage.This paper discussed the high efficacy of ET and its potential complications, which are mostly related to the design of the LAMS used. The high efficacy of LAMS in the transmural drainage of PPFCs is associated with lower treatment safety. Most ET complications respond to conservative or minimally invasive treatments, including endoscopic techniques. Surgical treatment of this type of complication remains the method of choice if other treatment options fail.This paper discusses possible directions of development in the field of transmural LAMSs. It may also be helpful in addressing the possible expectations of the interventional endoscopist towards stent designers and manufacturers. High hopes for improving the quality of endoscopic equipment are placed in the development of new technologies from biomedical materials, including polymers, equipment for the production of equipment. Possibly, subsequent novel endoprosthesis projects, based on the above results, will be able to meet the current needs and requirements associated with endoscopic endoscopic transmural drainage procedures in cases of postinflammatory PPFCs. The ultimate goal is to improve the safety of minimally invasive techniques for the treatment of the local consequences of pancreatitis. Hopefully, our findings will contribute to development of novel and original transmural LAMS designs.


The desire for foods with lower glycemic indices has led to the exploration of functional ingredients and novel food processing techniques. The glycemic index (GI) is a well-recognized tool to assess the capacity of foods to raise blood glucose levels. Among cereal crops, oats have shown the greatest promise for mitigating glycemic response. This review evaluated decades of research on the effects of oat components on the GI level of oat-based foods with specific emphasis on oat starch, β-glucans, proteins, and phenolics. The effects of commonly used processing techniques in oats on GI level, including heating, cooling, and germination were also discussed. In addition, the GI of oat-based foods in various physical formats such as whole grain, flakes, and flour was systematically summarized. The aim of this review was to synthesize knowledge of the field and to provide a deeper understanding of how the chemical composition and processing of oats affect GI, thereby further benefiting the development of low-GI oat foods. Avena sativa), whereas varieties cultivated in China are mainly without hulls (Avena nuda), which is often called naked oat . Pr. Pr65]. One purpose of heat treatment of oats is to inactivate endogenous enzymes, especially lipase, to prevent rancidity and extend shelf life. Another reason for such treatment is to produce products that consumers find more convenient, such as those that are easy to prepare ,69. UndeKiln drying is a typical step in oat processing. It inhibits lipase activity and prevents rancidity and corresponding off-flavor by imposing a certain temperature and moisture on raw oats. Such treatment can also produce a pleasant caramel aroma. The consistency of flavor and nutritional quality of the final oat products is largely dependent on the proper control of temperature, moisture content, and treatment period. Kiln drying is done typically at about 100 °C for up to about 2 h . In addiAnother treatment commonly applied in oats is extrusion. Extrusion cooking with high heat, pressure, and shear effects enhances starch gelatinization and structural changes, and this technique is used to make ready-to-eat oat products. Extrusion at 18% moisture content, 155 °C barrel temperature, and 150 rpm screw rotating speed gave the gelatinization degree of 96.92% in oat flour and led to a much easier release of glucose . HoweverDuring thermal processing, the GI of oat products is tightly associated with the degree of starch gelatinization that in turn affects the level of glucose releasing. Of these heat treatments that are commonly applied in oats, dry-heat treatment such as kiln drying may cause a more moderate impact on GI than hydrothermal treatment, including boiling and steaming, since the higher moisture facilitates the starch gelatinization and consequent digestion rate. Microwave heating is more likely to produce a lower GI than convectional heating because the structural change of starch seems different under microwave heating, but more studies are required on how this technique affects GI. Extrusion treatment produces a higher GI under the action of heat, shear, and pressure, due to the high gelatinization of starch and the depolymerization of β-glucans. Overall, reducing the starch gelatinization and corresponding digestibility by controlling the heat temperature, moisture, and time is an effective way to produce low-GI foods, which is beneficial to the management or the prevention of Type 2 diabetes.The cooling process is conducted generally after heating. In food processing, this step removes the thermal source by either naturally cooling or using a cooling apparatus. For oat products, cooling is commonly used for highly gelatinized foods with medium or high moisture content, whereas it is not suitable for slightly gelatinized products such as oat flakes. For instance, cooling is often used in the production of extruded oat noodles for the Chinese market to improve the texture and mouthfeel of the final product. Due to the lack of glutens, extruded oat noodles are formed by using the network structure generated from starch gelatinization. The starch retrogradation achieved by cooling makes the noodle structure more compact. During this process, the structure of gelatinized starch in food is rearranged to form a more structured matrix. This retrogradation of starch not only changes the texture but also affects digestibility and glycemic response. Cooling is a crucial determinant of starch retrogradation. At lower temperatures, the gelatinized starch is more easily to rearrange under the action of water molecules to form a relatively ordered structure. The degree of starch recrystallization increases with storage time. At a certain temperature, the retrogradation of amylose occurs mainly within a short storage period, while that of amylopectin happened in long-term storage. Therefore, the reduced digestibility is mainly the result of short storage. The retrogradation rate is also dominated by water content. Retrogradation is reduced by both low water content due to the restricted movement of starch molecules and high water content due to a dilution effect. Cooling is a potential strategy for producing low-GI foods, because this treatment allows the formation of starch retrogradation and consequently less digestibility. The retrograded starch is often less digestible, since a more ordered starch structure has decreased susceptibility to digestive enzymes. The most common cooling temperatures are 4 °C, 25 °C, and 30 °C; of these, 4 °C can produce a faster retrogradation rate of amylopectin . This prBioprocessing, including germination and fermentation, can effectively enhance the nutritional value and functional characteristics of oats. This kind of processing uses bioactive substances such as endogenous enzymes and microorganisms to change the nutritional composition and create a variety of functions .L. plantarum LP09 increased polyphenol availability and the antioxidant activity and decreased the hydrolysis index, showing a potential for reduced GI [Fermentation is a metabolic process that brings about a desirable change to a foodstuff under the activity of microorganisms. Yeast and lactic acid bacteria are commonly used to fermented oat products. There are few reports on the effect of fermentation on glycemic response in oats. The fermentation of oat flakes with duced GI . The orgduced GI . The pheduced GI . Germination is the process of growth from a plant seed to seeding. This process breaks down grain components into smaller substances through the action of endogenous grain enzymes when water, oxygen, and favorable temperatures are present. Germination alters nutrient availability, for example through the degradation of polysaccharides, and it decreases antinutrients . These fIn addition to natural biological processes, the direct addition of external enzymes is frequently used in the processing of oat products. This process is more commonly used for oat milk production. External enzymes such as α-amylase can help generate sweet flavors by catalyzing the partial hydrolysis of starch. Treatment with α-amylase improved the content of extractable phenolic compounds and the corresponding antioxidant capacity of oat flour . CarbohyThese bioprocessing techniques are drawing more and more interest to oat products, since they can change the quality and quantity of nutritional constituents. With regard to their effects on GI, current evidence mainly attributes them to oat phenolics. These bioactive components can reduce the absorption of glucose by inhibiting digestive enzymes, which is a potential therapeutic way to manage Type 2 diabetes . HoweverIn the United States, oats emerged as a food for the table in the 19th century. By virtue of its low cost and good flavor, oat-based breakfast cereals have gradually become a favorite food. With improved public awareness of the health benefits of eating oats, the oat processing industry has thrived. Not only does the traditional oatmeal and oat beverage market continue to expand, but new oat products, such as oat bars and oat rice, are also emerging. Based on the format of the ingredients, oat-based foods can be mainly classified as grains, flakes, flours, and other types such as oat bran. The production of these different ingredient formats mainly involves physical mechanical processing, such as pearling, rolling, and milling. A variety of oat products can be derived from these processed ingredients, and the corresponding size and thickness of the ingredient units determine to a large extent the GI level of the final product. The structural shape is closely associated with particle size in food matrices, and a more fragmentized structure increases the surface area and exposure of starch granules to amylolytic enzymes during digestion, leading to higher GI values. In this section, we discuss the GI of various oat-based foods by considering how it relates to the food format.After harvesting, dehulling, and cleaning, oat grains are ready either for consumption or further processing. As the least processed type, the intact grain structure maintains its original shape and retains the nutrients to the greatest extent. However, whole oat grains have a thick aleurone layer that slows water absorption and starch gelatinization during cooking. Whole grains also have a relatively hard texture and poor mouthfeel, and thus, the intact grain has not become a mainstream consumer product. Despite these challenges, a few whole grain-based oat products have emerged and captured certain markets by employing appropriate technology. For instance, pearled or “oat rice’’ has gained growing popularity in China with an annual consumption of 200,000 tons, since this product is compatible with the eating habits of Chinese consumers. Pearled oats is a whole-grain product processed by cleaning, dehulling, polishing, and inactivation of enzymes. Polishing is the most critical process as it removes the fluff (plant trichomes) and a specific amount of bran from the surface of oat grains, enabling the grain to absorb water and cook more quickly. This kind of product can be cooked with rice to produce a food with a special oat flavor and reduced GI value . Pearled(1)The grain structure is compact and intact, and the food can only be chewed and ground through the mouth. This minimal process ensures an intact cell wall and maintains a barrier to starch, thus reducing the accessibility to digestive enzymes and producing a lower GI value , (2)The outer aleurone layer of oat grains acts as a barrier to water absorption and starch gelatinization, thus retarding the starch hydrolysis and the release of glucose, and(3)The β-glucans and polyphenols-rich bran layer can delay gastric emptying and inhibit the activity of digestive enzymes .In general, intact oat grain products have relatively lower GI values ranging from 43.4 to 64.6 . Zhu et Oat flakes, also called rolled oats, are the most common oat product and are widely accepted by consumers worldwide. Oat flakes are made from whole oat grains (larger size) or steel-cut oats  by being rolled into flat flakes with thicknesses ranging from 0.4 mm to 1 mm . Steel-cCompared with oat grains, flake-shaped products undergo higher levels of processing and bear greater loss of nutritional properties. Heat treatments such as kilning or steaming can degrade some measures of nutritional quality. For example, flakes tend to exhibit higher GI values versus whole oat grains with a wide range from 44.7 to 114 , largelyWhole oat flours are produced with stone or hammer milling followed by mesh screening. The ground flours can serve as ingredients for other more processed products. This kind of ingredient is popular in Asian countries, including India and China. In India, whole grain oat flours are used to produce oat bread know as ‘jarobra’. In China, oat flours are commonly used to produce traditional foods, such as oat noodles and “oat wowo”, which is a steamed thin sheet of oat dough. Oat wowo and oat noodles are mainly consumed as staple foods in northern China, especially Inner Mongolia. Flour-based foods account for 70% of total oat foods with an annual production of 0.22 million tons in the Chinese market . Oat floCurrently, the GI values for only a few oat flour products are known, which are probably due to the small consumer base for such products. From the limited data generated in both in vitro and human trials, GI values range from 53.6 to 92. Oat mueslis or muffins show lower GI values, which is likely due partially to their supplementation with other ingredients such as raisins and dried fruits. Although the Dynamic In vitro Rat Stomach–Duodenum (DIVRSD) model gave relatively lower values of 54.4 and 61.8 . MoreoveOat bran is produced from grinding oat grain and separating the outermost bran layer from the rest of the grain. It can also be made from rolled oats. The corrugated rolls are reduced to the particle size of the steel-cut groats, and the coarse fraction, consisting of the oat bran, can then be separated . Oat braIn human clinical trials, the GI values of oat bran ranged from 34 to 66.3, which is lower than most other oat food matrices. In a clinical GI test using 12 hyperlipidemic patients, the value of oat bran was 59. Consuming commercial oat bran containing 22% β-glucans before meals in amounts of 4.5, 13.6, or 27.3 g remarkably reduced glycemia. When converted to β-glucans content in bran, each gram of β-glucan reduced the blood glucose iAUC by 4.35% ,102. In In summary, the components of oats contribute to the GI of a final food product to varying degrees. These components can interfere with starch hydrolysis and the corresponding absorbance of released glucose and increase product viscosity, causing a reduced gastric emptying rate. We evaluated the literature on several typical oat components and their impact on GI. As a critical substance for raising blood glucose, oat starch has a smaller granule size, making it more susceptible to digestive enzymes. Multi-faced factors including crystal characteristics, amylose content, and degree of branching collectively determine the overall GI level. The presence of RS2 and RS5 in raw oats may also contribute to the reduced GI to some extent. Among non-starch components, β-glucans are the most promising substance and have been successfully incorporated into a series of foods to produce low GI products. The β-glucan dose and molecular weight are crucial determinants affecting the viscosity and gastric emptying rate. The higher content of protein in oats is also an important factor that deserves attention. Although there is a lack of sufficient evidence to directly show the effect of oat proteins on glycemic response, it is thought that they can promote the secretion of insulin and increase the viscosity of food to slow gastric emptying. Oat phenolics are also important, and their inhibitory effects on digestive enzymes is possibly the mechanism through which these compounds reduce GI level.From the standpoint of a manufacturer, processing techniques that range from thermal to biotechnological affect starch digestibility and the activity of functional ingredients, thus modulating the glycemic response. Heat processing facilitates starch gelatinization and increases the GI to varied degrees, depending on the thermal conditions. Harsh conditions such as extrusion can cause the decomposition of other active compounds, such as β-glucans, thus increasing GI values. Cooling is commonly employed in highly gelatinized oat products. This step promotes starch retrogradation and can generate a certain amount of RS3, which reduces the GI level. Bioprocessing, including germination and fermentation, can facilitate the release of phenolics through enzymatic catalysis and thus exaggerate the inhibitory effect of phenolics on digestive enzymes.From field to table, oats are processed into various foods for consumption, and these foods exhibit high variability of GI values. The various physical formats of oat products are from the result of different degrees of physical and mechanical alteration. Grain, flake, and flour are typical ingredient forms for oat products. Minimum mechanical processing (grain) maintains the intact cell wall and larger particle size that reduce the accessibility to enzymes and thereby tend to enable lower GI values. In contrast, ultra-processing makes the starch more easily hydrated and increases the surface area available to enzymes. Another typical product, oat bran, affects GI behavior through the enrichment of dietary fibers. The systematic summary of GI of oat products with different physical formats presented in this review helps to synthesize knowledge of the field and provides practical guidance useful for management of diabetes with diet.The prevalence of diabetes has driven efforts to develop functional foods with the potential to lower glycemic response. For decades, oats have been used in efforts to reduce the GI of popular foods. Attempts to unravel the GI of oat-based foods have considered both the components of oats and the processing techniques used to generate food products. Tremendous research effort has been placed on β-glucans. The starch parameters and other bioingredients are also core factors affecting glycemic modulation, and their individual contributions are gradually becoming clearer. The lack of extensive knowledge of the interaction and co-contributions of the multiple components in oats are a challenge to our complete understanding of the GI effects of this important food ingredient. Future work should assess the multiple contributions of the various functional ingredients within oats and account for their synergistic or antagonistic effects on the GI of final products.