Helicobacter pylori infection alters gastric microbiota structure and biological functions in patients with gastric ulcer or duodenal ulcer.

BACKGROUND: Helicobacter pylori (H. pylori) infection is closely associated with gastrointestinal diseases. Our preliminary studies have indicated that H. pylori infection had a significant impact on the mucosal microbiome structure in patients with gastric ulcer (GU) or duodenal ulcer (DU). AIM: To investigate the contributions of H. pylori infection and the mucosal microbiome to the pathogenesis and progression of ulcerative diseases. METHODS: Patients with H. pylori infection and either GU or DU, and healthy individuals without H. pylori infection were included. Gastric or duodenal mucosal samples was obtained and subjected to metagenomic sequencing. The compositions of the microbial communities and their metabolic functions in the mucosal tissues were analyzed. RESULTS: Compared with that in the healthy individuals, the gastric mucosal microbiota in the H. pylori-positive patients with GU was dominated by H. pylori, with significantly reduced biodiversity. The intergroup differential functions, which were enriched in the H. pylori-positive GU patients, were all derived from H. pylori, particularly those concerning transfer RNA queuosine-modification and the synthesis of demethylmenaquinones or menaquinones. A significant enrichment of the uibE gene was detected in the synthesis pathway. There was no significant difference in microbial diversity between the H. pylori-positive DU patients and healthy controls. CONCLUSION: H. pylori infection significantly alters the gastric microbiota structure, diversity, and biological functions, which may be important contributing factors for GU.

Gastric microbiota transplantation as a potential treatment for immune checkpoint inhibitor-associated gastritis.

Immune-related adverse events (irAEs) are complications of the use of immune checkpoint inhibitors (ICIs). ICI-associated gastritis is one of the main irAEs. The gastric microbiota is often related to the occurrence and development of many gastric diseases. Gastric microbiota adjustment may be used to treat gastric disorders in the future. Faecal microbiota transplantation can alter the gut microbiota of patients and has been used for treating ICI-associated colitis. Therefore, we propose gastric microbiota transplantation as a supplementary treatment for patients with ICI-associated gastritis who do not respond well to conventional therapy.

Impact of high-altitude hypoxia on Helicobacter pylori-induced gastritis pathological manifestations and inflammatory responses.

BACKGROUND: Chronic gastritis caused by Helicobacter pylori (Hp) infection is a common gastrointestinal disorder. Despite the high prevalence of Hp infection and chronic gastritis in the Tibetan Plateau, there is a lack of studies elucidating the influence of plateau hypoxia on Hp-induced gastritis. This study aimed to investigate the impact of high-altitude hypoxia on Hp-induced gastritis, particularly focusing on pathological manifestations and inflammatory responses. METHODS: This study was conducted from July 2023 to March 2024 at the Department of Gastroenterology, Affiliated Hospital of Qinghai University. Ninety patients diagnosed with chronic gastritis were enrolled in the study and divided into four groups based on their residential altitude and Hp infection status. Data on endoscopic and pathological characteristics were collected, along with serum oxidative stress and inflammatory markers. RESULTS: Patients with Hp gastritis exhibit distinctive features in the gastric mucosa, including diffuse erythema, enlarged folds, and white turbid mucus during endoscopy. Notably, individuals with Hp gastritis at high altitudes show a higher prevalence of diffuse erythema and enlarged folds. Pathological analysis reveals that these patients have elevated gastric mucosal inflammation scores and increased chronic and active inflammation. Furthermore, individuals with Hp gastritis at high altitudes demonstrate elevated levels of serum TNF-α, IL-1ß, IL-6, and MDA, as well as reduced serum SOD and GSH-Px activities. CONCLUSIONS: High-altitude hypoxia may exacerbate gastric mucosal damage by enhancing oxidative stress and inflammatory response induced by Hp infection.

Human gastric microbiota analysis of refractory H. pylori infection.

H. pylori infection is gaining increasing attention, but detailed investigations into its impact on gastric microbiota remain limited. We collected gastric mucosa samples from 47 individuals divided into three groups: 1. Group HP: patients with initial positive H. pylori infection (25 cases); 2. Group ck: H. pylori-negative patients (14 cases); 3. Group DiffHP: patients with refractory H. pylori infection (8 cases). The samples were analyzed using 16S rDNA sequencing and functional prediction with PICRUSt. Group HP showed differences in flora distribution and function compared to Group ck, while Group DiffHP overlapped with Group HP. The abundances of Aeromonas piscicola, Shewanella algae, Vibrio plantisponsor, Aeromonas caviae, Serratia marcescens, Vibrio parahaemolyticus, Microbacterium lacticum, and Prevotella nigrescens were significantly reduced in both Group DiffHP and Group HP compared to Group ck. Vibrio shilonii was reduced only in Group DiffHP compared to Group ck, while Clostridium perfringens and Paracoccus marinus were increased only in Group DiffHP. LEfSe analysis revealed that Clostridium perfringens and Paracoccus marinus were enriched, whereas Vibrio shilonii was reduced in Group DiffHP compared to Group ck at the species level. In individuals with refractory H. pylori infection, the gastric microbiota exhibited enrichment in various human diseases, organic systems, and metabolic pathways (amino acid metabolism, carbohydrate metabolism, transcription, replication and repair, cell cycle pathways, and apoptosis). Patients with multiple failed H. pylori eradication exhibited significant changes in the gastric microbiota. An increase in Clostridium perfringens and Paracoccus marinus and a decrease in Vibrio shilonii appears to be characteristic of refractory H. pylori infection.

Unveiling early stage autoimmune gastritis: novel endoscopic insights from two case reports.

The predominant characteristic of autoimmune gastritis (AIG) is corpus-dominant advanced atrophy, which is mostly observed in the middle to late stages. More reports are needed on the endoscopic features of the early stage. In this report, we present two cases of early-stage AIG in which endoscopic examinations showed no atrophy of the gastric mucosa but displayed a transition of collecting venules from a regular to an irregular arrangement. In addition, yellowish-white cobblestone-like elevations were observed in the fundic gland region. Histologically, the observed manifestations included pseudohypertrophy and protrusion of parietal cells into the lumen, possibly along with hyperplasia of G cells, lymphocytic infiltration and potentially pseudopyloric gland metaplasia. Serologically, the anti-parietal cell antibody returned positive results, whereas the anti-intrinsic factor antibody yielded negative results. In this study, we summarized some endoscopic features of two patients, aiming to provide clues for endoscopists to detect early-stage AIG.

Detection of Helicobacter pylori infection in children using rapid urease and histologic methods of diagnosis.

Objective: The study aimed to detect the presence of Helicobacter pylori infection in children using two investigative methods: the rapid urease test and histological methods. It also examined the relationship between socioeconomic status and Helicobacter pylori infection. Design: This was a cross-sectional study conducted in the paediatric theatre at Korle Bu Teaching Hospital in Accra, Ghana. Participants: Children who were scheduled for upper gastrointestinal endoscopy were recruited into the study. Main outcome measures: The presence of Helicobacter pylori in gastric biopsies was measured using a rapid urease test and histology. Results: Seventy-three children aged 2 years to 16 years were seen during the period. Both tests were positive at the same time in 36 (49.3%) out of the 73 children (p<0.0001). The positivity rates for the rapid urease test and histology were 57.5% and 53.4 %, respectively. Significant predictors of the histology presence of H. pylori were a large household size of at least 6 members (AOR: 4.03; p<0.013) and the presence of pets at home (AOR: 3.23; p<0.044). Conclusions: Substantial agreement was found between the rapid urease test and histology examination of gastric biopsies for the presence of H. pylori. Children from large households and those with pets at home appear to have increased odds of having H. pylori infection of the gastric mucosa. Funding: None declared.

Concomitant Effects of Metformin and Vitamin C on Indomethacin-Induced Gastric Ulcer in Rats: Biochemical and Histopathological Approach.

INTRODUCTION: Gastric ulcer is one of the most common and serious conditions in the gastrointestinal tract. One of the main causes of gastric ulcers is using of non-steroidal anti-inflammatory drugs (NSAIDs) which have limited their use in clinical practice. Several studies have revealed that metformin and Vitamin C (Vit C) exhibit protective effects against gastric mucosal damage in different animal models. However, no studies indicate their combination's effect on gastric ulcer models. Therefore, this study aims to investigate the protective effects of metformin and Vit C combination on indomethacin-induced gastric ulcers. MATERIAL AND METHODS: In total, thirty rats were divided into six groups, including the control group, rats received indomethacin (50 mg/kg, i.p.), rats received indomethacin and pretreated with ranitidine (100 mg/kg), metformin (100 mg/kg, i.p.), Vit C (100 mg/kg), or metformin combined with Vit C. Four hours after indomethacin administration, rats were euthanized, and gastric tissues were removed for macroscopic, histopathologic, and biochemical examinations. RESULTS: All therapeutics used in this study were found to alleviate gastric mucosal injury caused by indomethacin, as observed in histopathologic and macroscopic evaluations. Both Vit C and metformin were observed to significantly decrease lipid peroxidation and enhance the activity of anti-oxidative enzymes, SOD, GPx, and catalase. However, a more significant effectiveness was observed in catalase and GPx activities when Vit C was co-administered with metformin. CONCLUSIONS: In conclusion, the present study revealed that metformin and Vit C combination therapy could potentially treat gastric ulcers associated with indomethacin.

EXPERIMENTAL STUDY OF THE EFFECT OF MINERAL WATERS ON THE GASTRIC MUCOSA OF WISTAR RATS.

Acid-related diseases (ARD) are the most common among digestive diseases. The main goals of therapy of ARD are to reduce the influence of aggression factors (production of HCl, pepsin) and increase the protective properties of the mucous membrane of the upper digestive tract. Also currently in medicine, one of the therapeutic and preventive methods is the use of chloride-hydrocarbonate sodium boron mineral waters. In this study, we compared the efficacy of table mineral waters in the therapy of induced gastropathy in Wistar rats. The study of the effect of mineral waters on the gastric mucosa of Wistar rats has provided valuable information that can be applied in medical practice for the treatment and prevention of various diseases of the gastrointestinal tract in humans. Careful analysis of the data obtained has shown that certain types of mineral waters can significantly reduce inflammatory processes and promote regeneration of the gastric mucosa, which makes them a useful addition to traditional treatment methods such as pharmacotherapy.

Calorie restriction activates a gastric Notch-FOXO1 pathway to expand ghrelin cells.

Calorie restriction increases lifespan. Among the tissue-specific protective effects of calorie restriction, the impact on the gastrointestinal tract remains unclear. We report increased numbers of chromogranin A-positive (+), including orexigenic ghrelin+ cells, in the stomach of calorie-restricted mice. This effect was accompanied by increased Notch target Hes1 and Notch ligand Jag1 and was reversed by blocking Notch with DAPT, a gamma-secretase inhibitor. Primary cultures and genetically modified reporter mice show that increased endocrine cell abundance is due to altered Lgr5+ stem and Neurog3+ endocrine progenitor cell proliferation. Different from the intestine, calorie restriction decreased gastric Lgr5+ stem cells, while increasing a FOXO1/Neurog3+ subpopulation of endocrine progenitors in a Notch-dependent manner. Further, activation of FOXO1 was sufficient to promote endocrine cell differentiation independent of Notch. The Notch inhibitor PF-03084014 or ghrelin receptor antagonist GHRP-6 reversed the phenotypic effects of calorie restriction in mice. Tirzepatide additionally expanded ghrelin+ cells in mice. In summary, calorie restriction promotes Notch-dependent, FOXO1-regulated gastric endocrine cell differentiation.

[Preparation of Lactobacillus paracei TK1501 postbiotic and its inhibitory effect against Helicobacter pylori infection in mice].

OBJECTIVE: To prepare a postbiotic using soybean fermentation product of Lactobacillus paracasei TK1501 and evaluate its inhibitory effect against Helicobacter pylori (Hp) infection in mice. METHODS: L. paracasei TK1501 was cultured for 32 h at 37 ℃ in an anaerobic condition for solid substrate fermentation with a solid to water ratio of 1:1.5 in the substrate and an inoculation density of 5×107 CFU/mL. The postbiotic was isolated and purified using macroporous resin XAD-16N adsorption, cation exchange chromatography and HPLC, and its stability and antibacterial activity were assessed. The inhibitory effect of this postbiotic against Hp infection was evaluated in a mouse model with gastric mucosal Hp infection, which were treated with the postbiotic via gavage for 4 weeks at the dose of 0.02 or 0.1 mL. Serum levels of TNF-α and IL-1ß of the mice were analyzed after the treatments, and gastric tissues of the mice were collected for HE staining. RESULTS: L. paracasei TK1501 postbiotic could be easily degraded by protease and had good thermal stability and tolerance to exposures to acid, base, and organic solvents. In the in vitro experiment, the postbiotic showed strong inhibitory effects in bacterial cultures of Staphylococcus aureus, Hp and other common pathogenic bacteria without obviously affecting the resident bacteria in the digestive tract. In the mouse models, treatment with the postbiotic at the dose of 0.1 mL significantly alleviated Hp infection and lowered the serum levels of TNF-α and IL-1ß of the mice. CONCLUSION: L. paracasei TK1501 postbiotic has strong inhibitory effects on Hp and Staphylococcus aureus but not on normal intestinal flora in mice.

[Identification of potential pathogenic genes of intestinal metaplasia based on transcriptomic sequencing and bioinformatics analysis].

OBJECTIVE: To explore the potential pathogenic genes of intestinal metaplasia. METHODS: Twenty-one patients with intestinal metaplasia admitted to the Department of Gastroenterology at the Second Affiliated Hospital of Anhui University of Chinese Medicine from January, 2022 to June, 2022, and 21 healthy subjects undergoing gastroscopic examination during the same period were enrolled in this study. All the participants underwent gastroscopy and pathological examination, and gastric tissue samples were collected for transcriptome sequencing to screen for differentially expressed genes (DEGs). The biological functions of the DEGs were analyzed using bioinformatics analysis, and qRT-PCR was used to validate the results. RESULTS: Transcriptomic sequencing identified a total of 1373 DEGs, including 827 upregulated and 546 downregulated ones. The top 6 upregulated genes (AGMAT, CCL25, FABP1, CDX1, SPINK4, and MUC2), ranked based on their significance and average expression level, were selected for validation, and qRT-PCR showed significant upregulation of their mRNAs in the gastric tissues of patients with intestinal metaplasia (P < 0.05). CONCLUSION: AGMAT, CCL25, FABP1, CDX1, SPINK4, and MUC2 participate in the occurrence and development of intestinal metaplasia, and may serve as potential biomarkers for diagnosing intestinal metaplasia.

Comparative Assessment of the Anti-Helicobacter pylori Activity and Gastroprotective Effects of Three Herbal Formulas for Functional Dyspepsia In Vitro.

Helicobacter pylori has been implicated in various gastrointestinal disorders, including functional dyspepsia. This study aimed to compare the anti-H. pylori activity and gastroprotective effects of three typical herbal formulas used for gastrointestinal disorders in Korea: Shihosogan-tang (ST), Yijung-tang (YT), and Pyeongwi-san (PS). Firstly, we assessed the total phenolic and flavonoid contents, as well as the antioxidative capacity. Additionally, we evaluated the antibacterial effect on H. pylori using an ammonia assay, minimum inhibitory concentration (MIC) test, and the disk agar diffusion method. Furthermore, we examined alterations in the gene expression of tight junction proteins, pro-inflammatory cytokines, and cellular vacuolation using an AGS cell model infected with H. pylori. While ST exhibited a higher total phenolic content, superior free radical scavenging, and inhibition of H. pylori compared to YT and PS, YT more evidently inhibited gastric cellular morphological changes such as vacuolation. All formulations significantly ameliorated changes in inflammatory and gastric inflammation-related genes and cellular morphological alterations induced by H. pylori infection. Overall, the present in vitro study suggests that all three herbal formulas possess potential for ameliorating gastrointestinal disorders, with ST relatively excelling in inhibiting H. pylori infection and inflammation, while YT potentially shows greater efficacy in directly protecting the gastric mucosa.

Trained Immunity and Trained Tolerance: The Case of Helicobacter pylori Infection.

Trained immunity is a concept in immunology in which innate immune cells, such as monocytes and macrophages, exhibit enhanced responsiveness and memory-like characteristics following initial contact with a pathogenic stimulus that may promote a more effective immune defense following subsequent contact with the same pathogen. Helicobacter pylori, a bacterium that colonizes the stomach lining, is etiologically associated with various gastrointestinal diseases, including gastritis, peptic ulcer, gastric adenocarcinoma, MALT lymphoma, and extra gastric disorders. It has been demonstrated that repeated exposure to H. pylori can induce trained immunity in the innate immune cells of the gastric mucosa, which become more responsive and better able to respond to subsequent H. pylori infections. However, interactions between H. pylori and trained immunity are intricate and produce both beneficial and detrimental effects. H. pylori infection is characterized histologically as the presence of both an acute and chronic inflammatory response called acute-on-chronic inflammation, or gastritis. The clinical outcomes of ongoing inflammation include intestinal metaplasia, gastric atrophy, and dysplasia. These same mechanisms may also reduce immunotolerance and trigger autoimmune pathologies in the host. This review focuses on the relationship between trained immunity and H. pylori and underscores the dynamic interplay between the immune system and the pathogen in the context of gastric colonization and inflammation.

Aggregation structure induced by heat treatments mediated the gastric digestion behavior of soybean protein.

The common belief that heat treatment enhances the gastric digestion of proteins is largely based on findings from animal proteins and may not apply to all proteins, particularly plant proteins. Here, we compared the digestion characteristics of soybean protein isolates (SPI) in an in vitro semi-dynamic digestion model and found distinct effects of heat treatment on the digestion properties of plant proteins. The results revealed that heat-treated SPIs formed clots during the early stages of digestion, although the clots gradually became smaller and looser as digestion progressed, the systems remained turbid at the end of gastric digestion, indicating the lag in their emptying. Furthermore, heat treatment altered the rheological properties of SPI, resulting in increased viscosity and slower gastric emptying. These effects became more pronounced with increasing heat treatment temperatures. The fluorescence spectrum analysis indicated that heat treatment altered its conformation. This led to protein unfolding and exposure of hydrophobic groups, facilitating the formation of larger aggregates during digestion. Additionally, heat treatment exposed more cleavage sites for gastric proteases, increasing the extent of hydrolysis. Elevated levels of free amino acids and a smaller molecular weight distribution further corroborated these findings. These findings contribute to a deeper understanding of the gastric digestion characteristics of plant proteins and the relationship between protein aggregation structure and the digestion process.

Research on drug treatment and the novel signaling pathway of chronic atrophic gastritis.

BACKGROUND: Chronic atrophic gastritis (CAG) is a global digestive system disease and one of the important causes of gastric cancer. The incidence of CAG has been increasing yearly worldwide. PURPOSE: This article reviews the latest research on the common causes and future therapeutic targets of CAG as well as the pharmacological effects of corresponding clinical drugs. We provide a detailed theoretical basis for further research on possible methods for the treatment of CAG and reversal of the CAG process. RESULTS: CAG often develops from chronic gastritis, and its main pathological manifestation is atrophy of the gastric mucosa, which can develop into gastric cancer. The drug treatment of CAG can be divided into agents that regulate gastric acid secretion, eradicate Helicobacter. pylori (H. pylori), protect gastric mucous membrane, or inhibit inflammatory factors according to their mechanism of action. Although there are limited specific drugs for the treatment of CAG, progress is being made in defining the pathogenesis and therapeutic targets of the disease. Growing evidence shows that NF-κB, PI3K/AKT, Wnt/ ß-catenin, MAPK, Toll-like receptors (TLRs), Hedgehog, and VEGF signaling pathways play an important role in the development of CAG.

[Clinical characteristics and literature review of ectopic gastric mucosa in the small intestine].

The study aims to summarize the clinical characteristics of patients with ectopic gastric mucosa in the small intestine, comparing clinical presentation differences between domestic and foreign patients through literature review. The clinical characteristics of cases diagnosed with ectopic gastric mucosa in the small intestine at Peking Union Medical College Hospital from January 2000 to January 2024 were retrospectively analyzed. By searching databanks, such as PubMed, EMBASE, the Cochrane Library, Wanfang, VIP, CNKI, and etc (the inclusion period was from the establishment of the database to January 1, 2024). The literature review was conducted on ectopic gastric mucosa in the small intestine. A total of 10 cases were included, all male, age [M (Q1, Q3)] was 27 (13-69) years old. Gastrointestinal bleeding was the first manifestation in most cases, with severe cases leading to hemorrhagic shock. Abdominal CT indicated local intestinal wall thickening and luminal narrowing in 3 cases. Four cases lesions were located at the beginning of the jejunum and 6 lesions were located in the end segment of ileum. All cases underwent local lesion resection, with postoperative pathology confirming ectopic gastric mucosa. Symptoms disappeared postoperatively, with a follow-up period of 0.5-3.0 years. Literature review indicates that the main clinical manifestation of gastric mucosa ectopia in the small intestine in China is gastrointestinal bleeding, while foreign patients are often complicated with intestinal duplication and intussusception, with abdominal pain and vomiting as the primary and main symptoms. The occurrence rate of intestinal obstruction in female patients, both domestically and abroad, is higher than that in male patients. The occurrence rate of ileal lesions with intestinal obstruction and small intestinal duplication is higher than that of duodenal lesions in both domestic and foreign patients. Local small intestine resection is an effective treatment method with generally good prognosis. Ectopic small intestinal mucosa is relatively rare, with symptoms of gastrointestinal bleeding and intestinal obstruction being common presentations, which can serve as one of the differential diagnoses for unexplained gastrointestinal bleeding.

Clinical, Pathological and Endoscopic Features of Neoplastic or Non-neoplastic Reddish Depressed Lesions after Helicobacter pylori Eradication.

BACKGROUND AND AIMS: Early gastric cancers (EGCs) after Helicobacter pylori (H. pylori) eradication often appear as reddish depressed lesions (RDLs); the same features are also appeared in benign stomachs after eradication. We compared clinic-pathological and endoscopic features of benign and neoplastic RDLs after H. pylori eradication. METHODS: 228 neoplastic RDLs after H. pylori eradication were studied. All lesions were divided into neoplastic RDLs (differentiated carcinoma or adenoma, n=114) and benign RDLs (n=114) according to the histology. Clinical and pathological characteristics were compared in neoplastic and benign groups. Endoscopic diagnostic yields using the white light (WL) endoscopy, chromoendoscopy (CE) using indigo carmine dye and the magnifying endoscopy with narrow-band imaging (ME-NBI) were also evaluated in relation to the pathological diagnosis. RESULTS: Size of neoplastic RDLs was larger than that of benign RDLs (p<0.01). Sensitivity, specificity and accuracy for predicting pathological types of RDLs was 70.1%, 52.6% and 61.4% for the WL, 65.8%, 63.1% and 65.4% for the CE, while the ME-NBI scored better with the 88.6%, 88.6%, 99.1% and 93.9% of sensitivity, specificity and accuracy. The accuracy of the ME-NBI was 99.9% (113/114) in the benign RDLs and 89.4% (101/114) for the neoplastic RDLs. Undiagnosed neoplastic RDLs using the ME-NBI were associated with more differentiated tumors such as adenoma and well-differentiated adenocarcinoma (tub1) and the presence of an unclear demarcation line. CONCLUSIONS: ME-NBI is useful to diagnose RDLs after H. pylori eradiation, while some of neoplastic lesions are difficult to diagnose using the ME-NBI.

Mucoadhesive Microspheres: A Promising Delivery System for Helicobacter Pylori (H. pylori) Treatment.

A major worldwide health problem, Helicobacter Pylori (H. pylori) infection is associated with a number of gastrointestinal disorders, such as gastric cancer and peptic ulcers. The shortcomings of traditional treatment plans often include adverse effects, low patient compliance, and the emergence of antibiotic resistance. Investigating different delivery methods is thus necessary to improve the effectiveness of treatment. Mucoadhesive microspheres show promise as a method for delivering anti H. pylori drugs in a targeted and sustained manner. With their ability to stick to the stomach mucosa, these microspheres increase the local concentration of the medication and guarantee a more thorough removal of the pathogen. The potential of Mucoadhesive microspheres in the management of H. pylori infection is examined in this review. We explore the properties and benefits of Mucoadhesive polymers, the production techniques for microspheres, and the variables affecting their functionality. To provide a thorough grasp of this delivery system, a variety of drug-loading strategies, release mechanisms, and in vitro and in vivo assessment methodologies are covered. The potential of Mucoadhesive microspheres to overcome the drawbacks of traditional therapy is shown by highlighting recent developments in their formulation and their therapeutic consequences. Mucoadhesive microspheres constitute an important advancement in the treatment of Helicobacter pylori because they guarantee a regulated release of antibiotics and improve medication absorption at the site of infection. In order to fully appreciate the advantages of this novel delivery method, further study is necessary. Future research paths and the difficulties in the clinical translation of this technology are also discussed.