The cecal appendix: one more immune component with a function disturbed by post-industrial culture

Therapeutic Potential of Essential Oils Against Ulcerative Colitis: A Review

Ulcerative colitis (UC) is a chronic non-sp ecific inflammatory disease of the colorectal mucosa. Researchers have associated UC onset with familial genetics, lifestyle behavior, inflammatory immune factors, intestinal microbiota, and the integrity of the intestinal mucosal barrier. The primary therapeutic interventions for UC consist of pharmacological management to control inflammation and promote mucosal healing and surgical interventions. The available drugs effectively control and decelerate the progression of UC in most patients; nonetheless, their long-term administration can exert adverse effects and influence the therapeutic effect. Plant essential oils (EOs) refer to a group of hydrophobic aromatic volatile substances. EOs have garnered considerable attention in both domestic and international research because of their anti-inflammatory, antibacterial, and antioxidant properties. They include peppermint, peppercorns, rosemary, and lavender, among others. Researchers have investigated the role of EOs in medicine and have elucidated their potential to mitigate the detrimental effects of UC through their anti-inflammatory, antioxidant, antidepressant, and anti-insomnia properties as well as their ability to regulate the intestinal flora. Furthermore, EOs exert minimal toxic adverse effects, further enhancing their appeal for therapeutic applications. However, these speculations are based on theoretical experiments, thereby warranting more clinical studies to confirm their effectiveness and safety. In this article, we aim to provide an overview of the advancements in utilizing natural medicine EOs for UC prevention and treatment. We will explore the potential pathogenesis of UC and examine the role of EOs therapy in basic research, quality stability, and management specification of inadequate EOs for UC treatment. We intend to offer novel insights into the use of EOs in UC prevention and management.

An International Consensus Survey among Pediatric Surgeons on the Role of Appendectomy in Malrotation

Introduction

Ladd's procedure, originally described in 1936 for the treatment of malrotation, does not traditionally include appendectomy as a standard step. We conducted a multinational survey to investigate the current consensus on the role of appendectomy in Ladd's procedure.

Methodology

An anonymous online survey was distributed to pediatric surgeons worldwide. The survey collected demographic data and explored surgical preferences related to the management of malrotation. Open-ended questions were used to assess the opinions regarding the necessity of appendectomy, decision-making factors, and complications associated with appendectomy during Ladd's procedure.

Results

A total of 343 responses were received from 46 countries. Of the respondents, 319 (93%) were consultants and 24 (7%) were residents/trainees. When asked about the choice between open and laparoscopic Ladd's procedure, 292 (85%) preferred open surgery. Overall, 184 (53%) respondents favored appendectomy in both open and laparoscopic Ladd's procedure. Furthermore, 172 (50%) surgeons advocated for appendectomy in all malrotation cases, citing concerns about potential future appendicitis. While differences existed between all comparisons, none of them reached statistical significance. The factors influencing the decision to preserve the appendix included the risk of postoperative complications and the potential future use of the appendix as a surgical conduit. The surgical complications following appendectomy included surgical site infections in 14 (33%) patients, adhesive obstruction in 13 (31%) patients, intrabdominal abscesses in 10 (24%) patients, and fecal fistulas in 5 (12%) patients.

Conclusion

The majority of surgeons aim to perform appendectomy in all malrotation cases, considering the potential risks and benefits of this approach. These findings offer valuable insights for clinical practice and may inform future guidelines and decision-making algorithms.

Colonoscopy in the diagnosis and management of appendiceal disease

In this editorial, we comment on the article published in the recent issue of the World Journal of Gastrointestinal Endoscopy. We focused on the understanding of appendiceal disease, and the various options for diagnosis and treatment via endoscopy. Some factors affecting the diagnosis and management of appendiceal diseases are also discussed. The existence of any organ has its natural rationality, and the appendix is such a magical organ. A growing number of experts and scholars have gradually come to a consensus that the appendix is not a useless evolutionary relic. There are many lymphocytes and lymph nodes in the appendix wall, which has a strong immune function, and this function is particularly important for children and adolescents. Many intestinal probiotics in the appendix are very helpful for maintaining the balance of the intestinal flora. With the continuous progress of endoscopic technology, endoscopic treatment involving preservation of the appendix has shown great advantages over surgery. In the diagnosis of appendiceal inflammation and neoplasms, colonoscopy, endoscopic retrograde appendicography and choledochoscopy help assess conditions of the appendix. Endoscopic retrograde appendicitis therapy, abscess drainage under colonoscopy, fenestration of abscess under colonoscopy, and endoscopic or natural orifice transluminal endoscopic surgery resection of appendiceal neoplasms are safe and effective endoscopic treatments for appendiceal disease. New breakthroughs in the application of endoscopy in the appendix are expected to occur in the near future.

Influenza A virus infection during pregnancy causes immunological changes in gut-associated lymphoid tissues of offspring mice

Maternal influenza A virus (IAV) infection during pregnancy can affect offspring immune programming and development. Offspring born from influenza-infected mothers are at increased risk of neurodevelopmental disorders and have impaired respiratory mucosal immunity against pathogens. The gut-associated lymphoid tissue (GALT) represents a large proportion of the immune system in the body and plays an important role in gastrointestinal (GI) homeostasis. This includes immune modulation to antigens derived from food or microbes, gut microbiota composition, and gut-brain axis signaling. Therefore, in this study, we investigated the effect of maternal IAV infection on mucosal immunity of the GI tract in the offspring. There were no major anatomical changes to the gastrointestinal tract of offspring born to influenza-infected dams. In contrast, maternal IAV did affect the mucosal immunity of offspring, showing regional differences in immune cell profiles within distinct GALT. Neutrophils, monocytes/macrophages, CD4+ and CD8+ T cells infiltration was increased in the cecal patch offspring from IAV-infected dams. In the Peyer's patches, only activated CD4+ T cells were increased in IAV offspring. IL-6 gene expression was also elevated in the cecal patch but not in the Peyer's patches of IAV offspring. These findings suggest that maternal IAV infection perturbs homeostatic mucosal immunity in the offspring gastrointestinal tract. This could have profound ramifications on the gut-brain axis and mucosal immunity in the lungs leading to increased susceptibility to respiratory infections and neurological disorders in the offspring later in life.NEW & NOTEWORTHY Influenza A virus (IAV) infection during pregnancy is associated with changes in gut-associated lymphoid tissue (GALT) in the offspring in a region-dependent manner. Neutrophils and monocytes/macrophages were elevated in the cecal patch of offspring from infected dams. This increase in innate immune cell infiltration was not observed in the Peyer's patches. T cells were also elevated in the cecal patch but not in the Peyer's patches.

Impaired cecal motility and secretion alongside expansion of gut-associated lymphoid tissue in the Nlgn3R451C mouse model of autism

Individuals with Autism Spectrum Disorder (ASD; autism) commonly present with gastrointestinal (GI) illness in addition to core diagnostic behavioural traits. The appendix, or cecum in mice, is important for GI homeostasis via its function as a key site for fermentation and a microbial reservoir. Even so, the role of the appendix and cecum in autism-associated GI symptoms remains uninvestigated. Here, we studied mice with an autism-associated missense mutation in the post-synaptic protein neuroligin-3 (Nlgn3R451C), which impacts brain and enteric neuronal activity. We assessed for changes in cecal motility using a tri-cannulation video-imaging approach in ex vivo preparations from wild-type and Nlgn3R451C mice. We investigated cecal permeability and neurally-evoked secretion in wild-type and Nlgn3R451C tissues using an Ussing chamber set-up. The number of cecal patches in fresh tissue samples were assessed and key immune populations including gut macrophages and dendritic cells were visualised using immunofluorescence. Nlgn3R451C mice displayed accelerated cecal motor complexes and reduced cecal weight in comparison to wildtype littermates. Nlgn3R451C mice also demonstrated reduced neurally-evoked cecal secretion in response to the nicotinic acetylcholine receptor agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP), but permeability was unchanged. We observed an increase in the number of cecal patches in Nlgn3R451C mice, however the cellular morphologies of key immune populations studied were not significantly altered. We show that the R451C nervous system mutation leads to cecal dysmotility, impaired secretion, and neuro-immune alterations. Together, these results suggest that the R451C mutation disrupts the gut-brain axis with GI dysfunction in autism.

Appendicitis is associated with an increased risk of systemic lupus erythematosus: a nationwide, population-based, case-control study

OBJECTIVE

To examine the association between appendicitis and the risk of systemic lupus erythematosus (SLE).

METHODS

Using claims data from the 2003-2013 Taiwanese National Health Insurance Research Database, we selected 6054 patients with newly diagnosed SLE from 2007 to 2012 and 36,324 age-, sex- and year of SLE diagnosis date-matched (1:6) non-SLE controls. After controlling for potential confounders, a multivariable conditional logistic regression model was used to calculate the adjusted odds ratio (aOR) with 95% confidence interval (CI) for the association of appendicitis history with SLE. Sensitivity analyses were conducted using various definitions of appendicitis. Subgroup analyses were conducted to examine possible modification effects by age, gender, level of urbanization, income and Charlson Comorbidity Index (CCI).

RESULTS

The average age of patients was 38 years old in both groups. The proportion of females was 86.5%. 75 (1.2%) of SLE cases and 205 (0.6%) of non-SLE controls had appendicitis history before the index date. After adjusting for potential confounding factors, appendicitis was associated with a higher risk of SLE (aOR, 1.84; 95% CI, 1.34-2.52), and such association remained robust after variation of appendicitis definition. No significant modification effects were found for the association between appendicitis and SLE by age, gender, urbanization level, income and CCI.

CONCLUSION

This nationwide, population-based case-control study demonstrates an association between appendicitis and incident SLE. Lack of individual smoking status is a major limitation. Key Points • Appendicitis was significantly associated with an increased risk of SLE. • Such association remained robust using various definitions of appendicitis.

Microbiome Structure and Mucosal Morphology of Jejunum Appendix and Colon of Rats in Health and Dysbiosis

Gut microbiota contributes to human health. Plenty of studies demonstrate that antibiotics can disrupt gut ecosystem leading to dysbiosis. Little is known about the microbial variation of appendix and its up/downstream intestine after antibiotic treatment. This study aimed to investigate the microbiome and mucosal morphology of jejunum, appendix, and colon of rats in health and dysbiosis. A rodent model of antibiotic-induced dysbiosis was employed. Microscopy was used to observe mucosal morphological changes. 16S rRNA sequencing was performed for identifying bacterial taxa and microbiome structure. The appendices of dysbiosis were found enlarged and inflated with loose contents. Microscopy revealed the impairment of intestinal epithelial cells. High-throughput sequencing showed the Operational Taxonomic Units changed from 361 ± 33, 634 ± 18, 639 ± 19 in the normal jejunum, appendix, colon to 748 ± 98, 230 ± 11, 253 ± 16 in the disordered segments, respectively. In dysbiosis, Bacteroidetes translocated inversely from the colon and appendix (0.26%, 0.23%) to the jejunum (13.87% ± 0.11%); the relative abundance of all intestinal Enterococcaceae increased, while Lactobacillaceae decreased. Several bacterial clusters were found correlated to the normal appendix, whereas nonspecific clusters correlated to the disordered appendix. In conclusion, species richness and evenness reduced in the disordered appendix and colon; similar microbiome patterns were shared between the appendix and colon regardless of dysbiosis; site-specific bacteria were missing in the disordered appendix. Appendix is likely a transit region involving in upper and lower intestinal microflora modulation. The limitation of this study is all the data were derived from rats. We must be cautious about translating the microbiome results from rats to humans.

Issues for patchy tissues: defining roles for gut-associated lymphoid tissue in neurodevelopment and disease

Individuals diagnosed with neurodevelopmental conditions such as autism spectrum disorder (ASD; autism) often experience tissue inflammation as well as gastrointestinal dysfunction, yet their underlying causes remain poorly characterised. Notably, the largest components of the body's immune system, including gut-associated lymphoid tissue (GALT), lie within the gastrointestinal tract. A major constituent of GALT in humans comprises secretory lymphoid aggregates known as Peyer's patches that sense and combat constant exposure to pathogens and infectious agents. Essential to the functions of Peyer's patches is its communication with the enteric nervous system (ENS), an intrinsic neural network that regulates gastrointestinal function. Crosstalk between these tissues contribute to the microbiota-gut-brain axis that altogether influences mood and behaviour. Increasing evidence further points to a critical role for this signalling axis in neurodevelopmental homeostasis and disease. Notably, while the neuroimmunomodulatory functions for Peyer's patches are increasingly better understood, functions for tissues of analogous function, such as caecal patches, remain less well characterised. Here, we compare the structure, function and development of Peyer's patches, as well as caecal and appendix patches in humans and model organisms including mice to highlight the roles for these essential tissues in health and disease. We propose that perturbations to GALT function may underlie inflammatory disorders and gastrointestinal dysfunction in neurodevelopmental conditions such as autism.

Appendix and Ulcerative Colitis: a Key to Explaining the Pathogenesis and Directing Novel Therapies?

The vermiform appendix is generally considered a redundant organ, but recent evidence suggests that the appendix could contribute to the pathogenesis of inflammatory bowel diseases, in particular ulcerative colitis (UC), and may even have a therapeutic role; however, mechanisms of the appendix involvement remain unclear. Here, we highlight current evidence on the link between the appendix and UC and consider plausible therapeutic implications. A literature search was conducted using PubMed and PubMed Central from inception to Nov 2021 using the terms "Appendix", "UC", "Appendix & UC," "Appendectomy", and "Peri-appendicular patch," including only articles published in English. Reference lists from the selected studies were manually searched and reviewed to gather additional related reports. Inflammation around the appendix ("peri-appendicular patch") has been frequently observed in UC patients without other cecal involvement, and this inflammation can even precede the onset of UC. Epidemiologic studies propose that appendectomy reduces the risk of developing UC or even the risk of flare after UC is diagnosed, although this remains controversial. We reviewed studies showing altered host-microbe interactions in the appendix in UC, which suggest that the appendix could act as a priming site for disease via alterations in the immune response and changes in microbiota carried distally to the colon. In summary, recent literature suggests a possible role for microbes and immune cells within the appendix; however, the role of the appendix in the pathogenesis of UC remains unclear. Further research could clarify the therapeutic potential related to this organ.

A review of the function and evolution of the cecal appendix

Since its initial discovery in the 1500s, the cecal appendix has been an anatomical structure of great intrigue, notorious for its inconvenient tendency to become inflamed and often require surgical intervention. Appendicitis is one of the most common indications for emergency abdominal surgery, costing healthcare systems billions of dollars globally and causing tens of thousands of deaths annually. Yet, recent studies have indicated that the appendix may serve important protective functions in fortifying the body's immune response against invading pathogens and re-inoculating the gut with commensal bacteria after periods of gastrointestinal illness. While the cecal appendix was once believed to be a synapomorphy of hominoids (humans and other great apes), recent studies suggested that it is a recurrent trait found in several other species of primates, rodents, lagomorphs, marsupials, and monotremes. Mapping appendiceal and other gastrointestinal traits across a mammalian consensus phylogeny revealed that the cecal appendix has evolved independently numerous times throughout mammalian evolution, significantly more than would be expected due to chance alone, suggesting that the appendix is adaptively advantageous. However, attempts to identify an overarching ecological, behavioral, dietary, or environmental factor driving some species to evolve an appendix have been largely unsuccessful, indicating that the cecal appendix has a complex and diverse evolutionary history. This review discusses the current understanding of the pathophysiology, evolution, and possible functions of the appendix, both within humans and broadly across the class Mammalia.

A concise pathophysiological model of acute appendicitis against the background of the COVID-19 pandemic

One of the most common clinical pictures has become the focus of attention during the COVID-19 pandemic: acute appendicitis with the associated diagnostics and therapy. The aim of the work is to show inconsistencies with regard to epidemiology, pathophysiology and therapy against the background of the pandemic with special attention to the conditions for children and to explain the pathophysiological processes that are likely to underlie the disease based on scientifically plausible models.

The cecal appendix is correlated with greater maximal longevity in mammals

The cecal appendix had been considered as a useless vestige since Darwin's work, but recent research questioned this idea demonstrating that the cecal appendix appeared among the mammals at least 80 million years ago and has made multiple and independent appearances without any obvious correlation with diet, social life, ecology, or size of the cecum. However, functions and probable selective advantage conferred by this anatomical structure still remain enigmatic. We found, through analyses of data on 258 mammalian species, that cecal appendix presence is correlated with increased maximal observed longevity. This is the first demonstration of a correlation between cecal appendix presence and life history. Interestingly, the classical evolutionary theory of aging that predicts an increased longevity when the extrinsic mortality is reduced has been questioned several times, but recent comparative studies asserted its validity in the taxa, which experience age-dependent and density-dependent mortality, as in mammals. Thus, the cecal appendix may contribute to the increase in longevity through a reduction of extrinsic mortality. A lower risk of fatal infectious diarrhea is one of the most plausible hypotheses that could explain it. However, several hypotheses coexist about the possible functions of the cecal appendix, and our results provide new insights about this much-disputed question. In addition, we show that the cecal appendix arose at least 16 times and was lost only once during the evolutionary history of the considered mammals, an asymmetry that supports the existence of a positive selective of this structure.

The Urologist and the Appendix: A Review of Appendiceal Use in Genitourinary Reconstructive Surgery

Recently, genitourinary reconstruction has experienced a renaissance. Over the past several years, there has been an expansion of the literature regarding the use of buccal mucosa for the repair of complex ureteral strictures and other pathologies. The appendix has been an available graft utilized for the repair of ureteral stricture disease and has been infrequently reported since the early 1900s. This review serves to highlight the use of the appendix for reconstruction in urology, particularly focusing on the anatomy and physiology of the appendix, historical use, and current applications, particularly in robotic upper tract reconstruction.

Appendectomy Is Associated With Alteration of Human Gut Bacterial and Fungal Communities

Recent research has revealed the importance of the appendix in regulating the intestinal microbiota and mucosal immunity. However, the changes that occur in human gut microbial communities after appendectomy have never been analyzed. We assessed the alterations in gut bacterial and fungal populations associated with a history of appendectomy. In this cross-sectional study, we investigated the association between appendectomy and the gut microbiome using 16S and ITS2 sequencing on fecal samples from 30 healthy individuals with prior appendectomy (HwA) and 30 healthy individuals without appendectomy (HwoA). Analysis showed that the gut bacterial composition of samples from HwA was less diverse than that of samples from HwoA and had a lower abundance of Roseburia, Barnesiella, Butyricicoccus, Odoribacter, and Butyricimonas species, most of which were short-chain fatty acids-producing microbes. The HwA subgroup analysis indicated a trend toward restoration of the HwoA bacterial microbiome over time after appendectomy. HwA had higher gut fungi composition and diversity than HwoA, even 5 years after appendectomy. Compared with those in samples from HwoA, the abundance correlation networks in samples from HwA displayed more complex fungal–fungal and fungal–bacterial community interactions. This study revealed a marked impact of appendectomy on gut bacteria and fungi, which was particularly durable for fungi.

Antibiotics and fecal transfaunation differentially affect microbiota recovery, associations, and antibiotic resistance in lemur guts

BACKGROUND

Antibiotics alter the diversity, structure, and dynamics of host-associated microbial consortia, including via development of antibiotic resistance; however, patterns of recovery from microbial imbalances and methods to mitigate associated negative effects remain poorly understood, particularly outside of human-clinical and model-rodent studies that focus on outcome over process. To improve conceptual understanding of host-microbe symbiosis in more naturalistic contexts, we applied an ecological framework to a non-traditional, strepsirrhine primate model via long-term, multi-faceted study of microbial community structure before, during, and following two experimental manipulations. Specifically, we administered a broad-spectrum antibiotic, either alone or with subsequent fecal transfaunation, to healthy, male ring-tailed lemurs (Lemur catta), then used 16S rRNA and shotgun metagenomic sequencing to longitudinally track the diversity, composition, associations, and resistomes of their gut microbiota both within and across baseline, treatment, and recovery phases.

RESULTS

Antibiotic treatment resulted in a drastic decline in microbial diversity and a dramatic alteration in community composition. Whereas microbial diversity recovered rapidly regardless of experimental group, patterns of microbial community composition reflected long-term instability following treatment with antibiotics alone, a pattern that was attenuated by fecal transfaunation. Covariation analysis revealed that certain taxa dominated bacterial associations, representing potential keystone species in lemur gut microbiota. Antibiotic resistance genes, which were universally present, including in lemurs that had never been administered antibiotics, varied across individuals and treatment groups.

CONCLUSIONS

Long-term, integrated study post antibiotic-induced microbial imbalance revealed differential, metric-dependent evidence of recovery, with beneficial effects of fecal transfaunation on recovering community composition, and potentially negative consequences to lemur resistomes. Beyond providing new perspectives on the dynamics that govern host-associated communities, particularly in the Anthropocene era, our holistic study in an endangered species is a first step in addressing the recent, interdisciplinary calls for greater integration of microbiome science into animal care and conservation.

Appendectomy and Non-Typhoidal Salmonella Infection: A Population-Based Matched Cohort Study

The potential association between appendectomy and non-typhoidal Salmonella (NTS) infection has not been elucidated. We hypothesized that appendectomy may be associated with gut vulnerability to NTS. The data were retrospectively collected from the Taiwan National Health Insurance Research Database to describe the incidence rates of NTS infection requiring hospital admission among patients with and without an appendectomy. A total of 208,585 individuals aged ≥18 years with an appendectomy were enrolled from January 2000 to December 2012, and compared with a control group of 208,585 individuals who had never received an appendectomy matched by propensity score (1:1) by index year, age, sex, occupation, and comorbidities. An appendectomy was defined by the International Classification of Diseases, Ninth Revision, Clinical Modification Procedure Codes. The main outcome was patients who were hospitalized for NTS. Cox proportional hazards models were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). Two sensitivity analyses were conducted for cross-validation. Of the 417,170 participants (215,221 (51.6%) male), 208,585 individuals (50.0%) had an appendectomy, and 112 individuals developed NTS infection requiring hospitalization. In the fully adjusted multivariable Cox proportional hazards regression model, the appendectomy group had an increased risk of NTS infection (adjusted HR (aHR), 1.61; 95% CI, 1.20-2.17). Females and individuals aged 18 to 30 years with a history of appendectomy had a statistically higher risk of NTS than the control group (aHR, 1.92; 95% CI, 1.26-2.93 and aHR, 2.67; 95% CI, 1.41-5.07). In this study, appendectomy was positively associated with subsequent hospitalization for NTS. The mechanism behind this association remains uncertain and needs further studies to clarify the interactions between appendectomy and NTS.

Impact of Appendectomy on Gut Microbiota

Background: Considered vestigial from the classic point of view, the vermiform appendix has long been the subject of intensive studies. The recent understanding of appendix function in the context of unique architecture and bacterial complexity and density allows considering it as a safehouse for intestinal biodiversity. Methods: This review analyzes and assesses the current state of scientific knowledge regarding the role of the vermiform appendix in normal gut microbiota maintenance as a crucial factor of host homeostasis. It also highlights the difference in microbial composition between the large bowel and the appendix, as well as the association between the surgical excision, appendectomy, and dysbiosis-induced diseases. In addition, the review discusses the results of epidemiologic studies on appendectomy as a risk factor for the initiation of gastrointestinal carcinogenesis. It also highlights the association between appendectomy and a series of chronic inflammatory and neurologic disorders, including inflammatory bowel disease.

Use of gene expression profiling to identify candidate genes for pretherapeutic patient classification in acute appendicitis

Background

Phlegmonous and gangrenous appendicitis represent independent pathophysiological entities with different clinical courses ranging from spontaneous resolution to septic disease. However, reliable predictive methods for these clinical phenotypes have not yet been established. In an attempt to provide pathophysiological insights into the matter, a genomewide gene expression analysis was undertaken in patients with acute appendicitis.

Methods

Peripheral blood mononuclear cells were isolated and, after histological confirmation of PA or GA, analysed for genomewide gene expression profiling using RNA microarray technology and subsequent pathway analysis.

Results

Samples from 29 patients aged 7–17 years were included. Genomewide gene expression analysis was performed on 13 samples of phlegmonous and 16 of gangrenous appendicitis. From a total of 56 666 genes, 3594 were significantly differently expressed. Distinct interaction between T and B cells in the phlegmonous appendicitis group was suggested by overexpression of T cell receptor α and β subunits, CD2, CD3, MHC II, CD40L, and the B cell markers CD72 and CD79, indicating an antiviral mechanism. In the gangrenous appendicitis group, expression of genes delineating antibacterial mechanisms was found.

Conclusion

These results provide evidence for different and independent gene expression in phlegmonous and gangrenous appendicitis in general, but also suggest distinct immunological patterns for the respective entities. In particular, the findings are compatible with previous evidence of spontaneous resolution in phlegmonous and progressive disease in gangrenous appendicitis.

Appendiceal Interposition for Ureteral Stricture Disease: Technique and Surgical Outcomes

OBJECTIVE

To report our initial experience with ureteral appendiceal interposition (UAI) in a series of adult patients undergoing ureteral reconstruction for ureteral stricture.

METHODS

We retrospectively collected data of patients who underwent UAI for ureteral stricture disease from December 2015 to March of 2020. Success of surgery was defined as one that required no subsequent procedural intervention for recurrent ureteral stricture disease, or loss of kidney function.

RESULTS

Eleven patients underwent UAI for ureteral stricture. Etiologies for stricture disease included radiation exposure, nephrolithiasis, and iatrogenic injury. Median follow-up was 363 days. Three patients had Clavien-Dindo class III complications during their hospitalization. No patient required repeat intervention due to recurrent ureteral stricture disease. On imaging, 9 patients had no obstruction on Lasix renal scan postoperatively, or improvement in hydronephrosis on CT scan. Two patients with poor renal function preop continued to show poor function after surgery.

CONCLUSION

The use of the appendix is a safe and feasible option for ureteral reconstruction in appropriately selected adult patients when primary ureteral repair is not possible.

Appendectomy as a Potential Predisposing Factor for the Development of Recurrent and Fulminant Clostridium Difficile

This literature review assesses how the vermiform appendix has been considered a vestigial organ by many, but over the years, new research has allowed us to reconsider its potential purpose. Studies have indicated that the appendix plays an evident role in immune response and harbors a biofilm that may remain unaffected by gastrointestinal infections, such as infection with Clostridium difficile. Our research analyzes the prominent gut-associated lymphoid tissue (GALT) as a mechanism of defence in infection, as well as the robust biofilm that could aid in the reinoculation of beneficial bacteria within the colon. Furthermore, we wanted to determine if patients who have undergone a prior appendectomy, leading to decreased GALT and a lack of a bacterial reservoir, were predisposed to the development of Clostridium difficile, with particular emphasis in the recurrence and development of fulminant Clostridium difficile infections. Although research continues to be conflicting, there appears to be some connection between these variables, but prospective studies are needed in order to say for certain that there is a link.

Autism-associated synaptic mutations impact the gut-brain axis in mice

Interactions between the gut microbiome and the brain affect mood and behaviour in health and disease. Using preclinical animal models, recent discoveries begin to explain how bacteria in the gut influence our mood as well as highlighting new findings relevant to autism. Autism-associated gene mutations known to alter synapse function in the CNS also affect inflammatory response and modify the enteric nervous system resulting in abnormal gastrointestinal motility and structure. Strikingly, these mutations additionally affect the gut microbiome in mice. This review describes the changes in gut physiology and microbiota in mouse models of autism with modified synapse function. The rationale for different regions of the gastrointestinal tract having variable susceptibility to dysfunction is also discussed. To dissect underlying biological mechanisms involving gut-brain axis dysfunction in preclinical models, a range of multidisciplinary approaches are required. This research will provide insights into the role of the gut-brain axis in health and neurodevelopmental disorders including autism.

Spatial Compartmentalization of the Microbiome between the Lumen and Crypts Is Lost in the Murine Cecum following the Process of Surgery, Including Overnight Fasting and Exposure to Antibiotics

The cecum is a unique region in the mammalian intestinal tract in which the microbiome is localized to two compartments, the lumen and the crypts. The microbiome within crypts is particularly important as it is in direct contact with lining epithelial cells including stem cells. Here, we analyzed the microbiome in cecum of mice using multiple techniques including metagenomics. The lumen microbiome comprised Firmicutes and Bacteroidetes whereas the crypts were dominated by Proteobacteria and Deferribacteres, and the mucus comprised a mixture of these 4 phyla. The lumen microbial functional potential comprised mainly carbon metabolism, while the crypt microbiome was enriched for genes encoding stress resistance. In order to determine how this structure, assembly, and function are altered under provocative conditions, we exposed mice to overnight starvation (S), antibiotics (A), and a major surgical injury (partial hepatectomy [H]), as occurs with major surgery in humans. We have previously demonstrated that the combined effect of this "SAH" treatment leads to a major disturbance of the cecal microbiota at the bottom of crypts in a manner that disrupts crypt cell homeostasis. Here, we applied the SAH conditions and observed a loss of compartmentalization in both composition and function of the cecal microbiome associated with major shifts in local physicochemical cues including decrease of hypoxia, increase of pH, and loss of butyrate production. Taken together, these studies demonstrated a defined order, structure, and function of the cecal microbiome that can be disrupted under provocative conditions such as major surgery and its attendant exposures.IMPORTANCE The proximal colon and cecum are two intestinal regions in which the microbiome localizes to two spatially distinct compartments, the lumen and crypts. The differences in composition and function of luminal and crypt microbiome in the cecum and the effect of physiological stress on their compartmentalization remain poorly characterized. Here, we characterized the composition and function of the lumen-, mucus-, and crypt-associated microbiome in the cecum of mice. We observed a highly ordered microbial architecture within the cecum whose assembly and function become markedly disrupted when provoked by physiological stress such as surgery and its attendant preoperative treatments (i.e., overnight fasting and antibiotics). Major shifts in local physicochemical cues including a decrease in hypoxia levels, an increase in pH, and a loss of butyrate production were associated with the loss of compositional and functional compartmentalization of the cecal microbiome.

Risk of irritable bowel syndrome in patients who underwent appendectomy: A nationwide population-based cohort study

BACKGROUND

Appendectomy is one of the most common surgical procedures; however, the possible long-term consequences have not been fully explored. The appendix has been associated with microflora of the gut and immune functions. However, literature examining the relationship between prior appendectomy and the risk of irritable bowel syndrome (IBS) is lacking. The aim of this study was to evaluate the risk of irritable bowel syndrome for patients who underwent appendectomy by using a nationwide longitudinal population-based cohort.

METHODS

Data from this study was collected from Taiwan's National Health Insurance Research Database (NHIRD), a population-based database. We identified 12,760 patients who underwent appendectomy between January 1, 2000 and December 31, 2012. A total of 9236 patients who had appendectomy (case group) were randomly matched with 9236 patients who had not undergone appendectomy (control group) in a ratio of 1:1 by means of propensity scores. The hazard ratio (HR) of IBS was calculated by multiple Cox regression. Furthermore, sensitivity test and stratified analysis were performed.

FINDINGS

The incidence rate of IBS was 51.30 per 10,000 person-years in patients having appendectomy, more than the 35.28 per 10,000 person-years in patients not having appendectomy. Patients who underwent appendectomy had 1.46-fold risk of IBS compared to patients not having appendectomy (HR, 1.46; 95% CI, 1.24-1.72). Stratified analysis revealed that the higher HR of 1.55 (95% CI, 1.18-2.04) in patients <40 years old, and particularly within the first 5 years follow-up period of undergoing appendectomy. In addition, patients diagnosed with fibromyalgia had a greater risk of suffering IBS after appendectomy (HR, 1.41; 95% CI, 1.04-1.92).

INTERPRETATION

Patients with appendectomy have a higher incidental risk of IBS than the control population. The risk is higher for patients under 40 years old and those who received appendectomy within 5 years. Physicians could take this into consideration for treatment plans of patients who have underwent this surgery. Further research on the pathogenesis of this association is required.

FUNDING

This work was supported by grants from the Ministry of Health and Welfare, Taiwan (MOHW108-TDU-B-212-133004), China Medical University Hospital, Academia Sinica Stroke Biosignature Project (BM10701010021), MOST Clinical Trial Consortium for Stroke (MOST 108-2321-B-039-003-), Tseng-Lien Lin Foundation, Taichung, Taiwan, and Katsuzo and Kiyo Aoshima Memorial Funds, Japan.

The gallbladder and vermiform appendix influence the assemblage of intestinal microorganisms

Surgical procedures for the symptomatic removal of the gallbladder and the vermiform appendix have been posited to adversely shift the assemblage of the intestinal microbiome increasing the risk of disease. The associated mechanisms have been linked with dysbiosis of the gut microbiota. Cholecystectomy causes changes of bile acid compositions and bile secretion patterns as bile acids interact with the intestinal microbiota in a bidirectional capacity. An appendectomy precludes the further recolonization of the proximal colon with a commensal biofilm that could maintain a stable intestinal microbiome. Epidemiological studies indicate that there is an increased risk of disease rather than causality following a cholecystectomy and appendectomy. This narrative review summarizes studies that report on the role that bile salts and the appendix, contribute to the assemblage of the intestinal microbiome in health and disease.

Increased risk of gallstones after appendectomy: A longitudinal follow-up study using a national sample cohort

To evaluate the association between appendectomy and the occurrence of gallstones using a national sample cohort from Korea.The Korean National Health Insurance Service-National Sample Cohort was collected from 2002 to 2013. We extracted data for patients who had undergone appendectomy (n = 14,955) and a 1:4 matched control group (n = 59,820) and then analyzed the occurrence of gallstones. The patients were matched according to age, sex, income, region of residence, hypertension, diabetes mellitus, and history of dyslipidemia. Appendectomies were identified using operation codes (Q2860-Q2863) for appendicitis alone (International Classification of Disease-10: K35). Gallstones were diagnosed if the corresponding International Classification of Disease-10 code (K80) was reported ≥2 times. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using stratified Cox proportional hazard models, and 95% confidence intervals were calculated. Subgroup analyses were performed based on age, sex, and time period after appendectomy.The adjusted HR for gallstones was 1.78 (95% confidence interval = 1.51-2.09, P < .001) in the appendectomy group. Consistent HRs were found in the analyses of all the subgroups determined using age and sex, with the exception of men ≥60 years of age. The risk of gallstones was increased during the first year after appendectomy.The occurrence of gallstones was increased in the patients who had undergone appendectomy.

A prospective study of discrepancy between clinical and pathological diagnosis of appendiceal mucinous neoplasm

Purpose

Appendiceal tumoral lesions can occur as benign, malignant, or borderline disease. Determination of the extent of surgery through accurate diagnosis is important in these tumoral lesions. In this study, we assessed the accuracy of preoperative CT and identified the factors affecting diagnosis.

Methods

Patients diagnosed or strongly suspected from July 2016 to June 2019 with appendiceal mucocele or mucinous neoplasm using abdominal CT were included in the study. All the patients underwent single-incision laparoscopic cecectomy with the margin of cecum secured at least 2 cm from the appendiceal base. To compare blood test results and CT findings, the patients were divided into a mucinous and a nonmucinous group according to pathology.

Results

The total number of patients included in this study was 54 and biopsy confirmed appendiceal mucinous neoplasms in 39 of them. With CT, the accuracy of diagnosis was 89.7%. The mean age of the mucinous group was greater than that of the nonmucinous group (P = 0.035). CT showed that the maximum diameter of appendiceal tumor in the mucinous group was greater than that in the nonmucinous group (P < 0.001). Calcification was found only in the appendix of patients in the mucinous group (P = 0.012). Multivariate analysis revealed that lager tumor diameter was a factor of diagnosis for appendiceal mucinous neoplasm.

Conclusion

The accuracy of preoperative diagnosis of appendiceal mucinous neoplasms in this study was 89.7%. Blood test results did not provide differential diagnosis, and the larger the diameter of appendiceal tumor on CT, the more accurate the diagnosis.

Appendectomy and rheumatoid arthritis: A longitudinal follow-up study using a national sample cohort

The present study evaluated the association between appendectomy and rheumatoid arthritis (RA) using a national sample cohort of the Korean population. In this cohort study, the Korean National Health Insurance Service-National Sample Cohort of individuals ≥20 years old was collected from 2002 to 2013. A total of 14,995 appendectomy participants were 1:4 matched with 59,980 control subjects for age, group, sex, income group, region of residence, hypertension, diabetes, and dyslipidemia. We analyzed the occurrence of RA in both the appendectomy and control groups. Appendectomies were identified using operation codes for appendicitis only. RA was defined by International Classification of Disease-10 codes (M05 or M06) and medication histories. Crude and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. Subgroup analyses were performed on groups stratified by age and sex. The adjusted HR for RA was 1.02 (95% confidence interval = 0.76-1.38) in the appendectomy group (P = .883). In all of the subgroup analyses according to age and sex, the adjusted HRs for RA were not higher in the appendectomy group than those in the control group. We could not identify any significant relationship between appendectomy and RA.

Different distribution of mucosal-associated invariant T cells within the human cecum and colon

Introduction

Mucosal-associated invariant T (MAIT) cells are innate-like T cells that are involved in anti-bacterial immunity. MAIT cells are found in the intestines, but their role and distribution within the large intestine have not been fully elucidated. Therefore, we investigated the distribution of MAIT cells within the cecum and colon.

Material and methods

Surgically resected tissues of the cecum and colon were obtained from 4 patients with cecal appendix cancer and 8 patients with colorectal cancer, respectively. Lymphocytes were isolated from the intestinal epithelium (intraepithelial lymphocytes – IELs) and the underlying lamina propria (lamina propria lymphocytes – LPLs), and then, MAIT cells were analyzed by flow cytometry.

Results

Compared with the colon, the cecum showed a significantly increased frequency of MAIT cells among IELs (p < 0.01). CD69 expression on MAIT cells was significantly increased in the cecum and colon compared with that in the blood, and the frequency of natural killer group 2, member A⁺ cells among MAIT cells was significantly increased in the cecum.

Conclusions

These results suggest that the distribution of MAIT cells was different between the cecum and colon and that MAIT cells were more likely to be activated, especially in the intestinal epithelium of the cecum than in the colon and blood.

The vermiform appendix: an immunological organ sustaining a microbiome inoculum

The hominoid vermiform appendix has been characterized as a diverticulum of the caecum and describes an entity at the juxtaposition of the colon in the confluence of tanias. The independent development of the lymphoid follicle centres of the appendix is progressed at birth in the presence of the intestinal commensal microbiome, an obligatory prompt for the diversification of intestinal and extra-intestinal mucosal immunological tissue. In the vermiform appendix, this activity is centred on further developing the inventory of primary antibodies and the maturation of T- and B-lymphocyte cells in the follicles within the lymphoid tissue. Furthermore, the columnar epithelia, enterocytes and goblet cells comprise the complement of cells that occupy the lamina propria and muscularis mucosae of the vermiform appendix's mucosa, while macrophages and an abundance of immunoglobulin A and immunoglobulin G generating plasma cells seed the lamina propria Intraepithelial immune cells consisting predominantly of specific CD8⁺ T regulatory lymphocytes occupy sites in the appendix analogous to those present in the intestinal epithelia of the caecal colon. The complement of bacterial genera concealed in the vermiform appendix is posited extant as a biofilm inoculum of the intestinal commensal microbiome. This facilitates re-inoculation of the proximal colon and to a lesser degree the terminal ilium post an intestinal perturbation such as occurs with daily lifestyle stressors, dietary choices and the short-term administration of antibiotics rather than an infectious fulminant colitis. A plausible appreciation results of the importance of multiple immunological aspects of a healthy vermiform appendix and the provision of a commensal biofilm to the gut that repairs a dysbiotic microbiome contributing to balancing intestinal pro- and anti-inflammatory activity for maintaining homeostasis in the gut. Since the composition of the gut microbiome can vary over the short-term and long-term, it is plausible that the appendix inoculum may be instrumental in maintaining the intestinal microbiome.

Impact of age at appendectomy on development of type 2 diabetes: A population-based cohort study

Aim

Diabetes is a complex metabolic disease characterized by chronic low-grade inflammation in which genetic and environmental factors are involved. Growing evidence implicates that alterations of the gut microbiota potentially contribute to the emergence of metabolic diseases. The human appendix has more recently been recognized as a microbial reservoir for repopulating the gastrointestinal tract and an important part of the immune system. Thus, appendectomy may influence microbial ecology and immune function. This study investigated the association between appendectomy and type 2 diabetes risk.

Methods

We analyzed a cohort of 10954 patients who underwent appendectomy between 1998 and 2013 based on the Taiwan National Health Insurance Program database. A comparison cohort of 43815 persons without appendectomy was selected randomly and matched by sex, age, comorbidities, and index year. To ensure reliability of the results, a sensitivity analysis using a propensity score–matched study was performed. We observed the subsequent development of type 2 diabetes in both cohorts.

Results

Although the overall incidence of type 2 diabetes in the appendectomy patients was 7.9% higher than that in the non-appendectomy patients, it was not statistically significant (95% confidence interval [CI], 0.997–1.168) after the adjustment of confounding factors. Multivariate regression analysis revealed that the adjusted hazard ratio (HR) of type 2 diabetes was 1.347 for appendectomy patients < 30 years of age (95% CI, 1.009–1.798) compared to non-appendectomy patients. The incidence of type 2 diabetes was higher within 3 years of post-appendectomy follow-up than for non-appendectomy patients (HR, 2.017; 95% CI, 1.07–3.802). Age impacted the association between appendectomy and type 2 diabetes risk (P_interaction = 0.002); in contrast, sex did not affect the association between appendectomy and type 2 diabetes risk (P_interaction = 0.88).

Conclusions

Our study results suggest that appendectomy increases type 2 diabetes risk, particularly when performed prior to middle age.

Women who had appendectomy have increased risk of systemic lupus erythematosus: a nationwide cohort study

The appendix is involved in immune function, and an appendectomy may alter the immune system. Studies evaluating the relationship between previous appendectomy and the risk of systemic lupus erythematosus (SLE) are lacking. This nationwide cohort study investigated the incidence and risk of SLE in patients who underwent appendectomy. Patients aged > 20 years who received appendectomy from 2000 to 2011 were identified from the National Health Insurance Research Database and assigned to the appendectomy cohort. Patients without appendectomy were randomly selected from the NHIRD and assigned to the control cohort; they were frequency matched to each study patient at a 4:1 ratio by sex, age, and index year. All patients were followed until SLE diagnosis, withdrawal from the National Health Insurance program, or the end of 2011. We used Cox models to estimate the hazard ratio (HR) and 95% confidence interval (CI) to compare the risk of SLE between the appendectomy and control cohorts. From 23.74 million people in the cohort, 80,582 patients undergoing appendectomy and 323,850 patients without appendectomy were followed for 723,438 and 2,931,737 person-years, respectively. The appendectomy cohort had a 2.04-fold higher risk of SLE than the control cohort (adjusted HR = 2.04, 95% CI = 1.52-2.76). Women aged ≤ 49 years who underwent appendectomy had a 2.27-fold higher risk of SLE than the corresponding controls (adjusted HR = 2.27, 95% CI = 1.62-3.19). Women aged ≤ 49 years who underwent appendectomy have a significantly higher risk of SLE.

Appendectomy as a Risk Factor for Bacteremic Biliary Tract Infection Caused by Antibiotic-Resistant Pathogens

Background/Aims

Recent evidence has suggested that appendix plays a pivotal role in the development and preservation of intestinal immune system. The aim of this study is to examine whether prior appendectomy is associated with an increased risk for the development of antibiotic-resistant bacteria in bacteremia from biliary tract infection (BTI).

Methods

Charts from 174 consecutive cases of bacteremia derived from BTI were retrospectively reviewed. Using multivariate analysis, independent risk factors for development of antibiotic-resistant bacteria were identified among the clinical parameters, including a history of appendectomy.

Results

In total, 221 bacteria strains were identified from 174 BTI events. Of those, 42 antibiotic-resistant bacteria were identified in 34 patients. Multivariate analysis revealed that prior appendectomy (Odds ratio (OR), 3.02; 95% confidence interval (CI), 1.15–7.87; p = 0.026), antibiotic use within the preceding three months (OR, 3.06; 95% CI, 1.26–7.64; p = 0.013), and bilioenteric anastomosis or sphincterotomy (OR, 3.77; 95% CI, 1.51–9.66; p = 0.0046) were independent risk factors for antibiotic-resistant bacteria.

Conclusions

Prior appendectomy was an independent risk factor for the development of antibiotic-resistant bacteria in bacteremia from BTI.

Appendectomy, tonsillectomy, and risk for sarcoidosis - A hospital-based case-control study in Japan

BACKGROUND

The role of surgery in the onset of sarcoidosis is unclear. We investigated whether surgery is an internal environmental factor for sarcoidosis onset within the Japanese population.

METHODS

We enrolled 222 patients diagnosed with sarcoidosis (78 men, 144 women) who were admitted to our department between 1984 and 2012. We also enrolled 529 control subjects (251 men, 278 women), who were matched for sex, age at admission, and year of admission. Surgical history, family history, and smoking status were evaluated.

RESULTS

Multivariate analysis correlated history of appendectomy (OR, 1.55; 95% CI, 1.05-2.29) and tonsillectomy (OR, 2.79; 95% CI, 0.91-8.56) with the occurrence of sarcoidosis; other surgical procedures had no correlation. In women, appendectomy had a stronger association with sarcoidosis (OR, 1.69; 95% CI, 1.05-2.73), as opposed to that in men (OR, 1.39; 95% CI, 0.68-2.85). This association was greater in women aged ≥45 years than in those aged <45 years. There was a stronger correlation between tonsillectomy and sarcoidosis in women (OR, 3.30; 95% CI, 0.88-12.39), than in men (OR, 1.26; 95% CI, 0.10-16.52). ORs for sarcoidosis were 5.55 (95% CI, 2.02-15.27) and 0.97 (95% CI, 0.52-1.84) in women aged ≥45 years with a history of appendectomy at <20 years and ≥20 years, respectively, with the former being statistically significant.

CONCLUSIONS

Appendix and tonsil removal was associated with sarcoidosis onset, suggesting their potential protective role against sarcoidosis development. Further studies are needed to minimize possible confounding factors.

Asthma and Risk of Appendicitis in Children: A Population-Based Case-Control Study

OBJECTIVE

To assess whether asthma is associated with risk of appendicitis in children.

METHODS

We used a population-based case-control study design using a comprehensive medical record review and predetermined criteria for appendicitis and asthma. All children (age younger than 18 years of age) who resided in Olmsted County, Minnesota, and developed appendicitis between 2006 and 2012 were matched to controls (1:1) with regard to birthday, gender, registration date, and index date. Asthma status was ascertained using predetermined criteria. Active (current) asthma was defined as the presence of asthma symptoms or asthma-related events (eg, medication use, clinic visits, emergency department, or hospitalization) within 1 year before the index date. Inactive asthma was defined as subjects without these events. A conditional logistic regression model was used.

RESULTS

Among the 309 appendicitis cases identified, when stratified according to asthma status, active asthma was associated with significantly increased risk of appendicitis compared with inactive asthma (odds ratio [OR] = 2.48; 95% confidence interval [CI], 1.22-5.03) and to no asthma (OR = 1.88; 95% CI, 1.07-3.27; overall P = .035). When controlling for potential confounders such as gender, age, and smoking status, active asthma was associated with a higher odds of developing appendicitis compared with nonasthmatic patients (adjusted OR = 1.75; 95% CI, 0.99-3.11) whereas inactive asthma was not (overall P = .049). Tobacco smoke exposure within 3 months was associated with an increased risk of appendicitis (adjusted OR = 1.66; 95% CI, 1.02-2.69). Among asthma medications, leukotriene receptor antagonists reduced the risk of appendicitis (OR = 0.18; 95% CI, 0.04-0.74).

CONCLUSIONS

Active asthma might be an unrecognized risk factor for appendicitis in children whereas a history of inactive asthma does not pose such risk. Further investigation exploring the underlying mechanisms is warranted.

The appendix: a spectrum of benign and malignant disease

This article discusses the radiological appearances and subsequent management of a diverse spectrum of benign and malignant appendiceal pathologies, including those masquerading as acute appendicitis.

The immunology of the vermiform appendix: a review of the literature

This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of the appendiceal biofilm in particular has proved to have a beneficial effect for the entire gut. In assessing the influence of acute appendicitis and the importance of a normally functioning gut flora, however, multiple immunological aspects point towards the appendix as a priming site for ulcerative colitis. Describing the immunological and microbiotical changes in the appendix during acute and chronic inflammation of the appendix, this review suggests that this association becomes increasingly plausible. Sustained by the distinct composition of cells, molecules and microbiota, as well as by the ever more likely negative correlation between the appendix and ulcerative colitis, the idea of the appendix being a vestigial organ should therefore be discarded.

Appendectomy correlates with increased risk of pyogenic liver abscess: A population-based cohort study in Taiwan

Little is known on the association between appendectomy and pyogenic liver abscess. The objective of this study was to investigate the association between appendectomy and the risk of pyogenic liver abscess in Taiwan.This population-based retrospective cohort study was conducted using the hospitalization dataset of the Taiwan National Health Insurance Program. There were 212,530 subjects age 20 to 84 years with newly diagnosed appendectomy as the appendectomy group since 1998 to 2010, and 850,099 randomly selected subjects without appendectomy as the nonappendectomy group. Both appendectomy and nonappendectomy groups were matched with sex, age, comorbidities, and index year of diagnosing appendectomy. The incidence of pyogenic liver abscess at the end of 2011 was estimated in both groups. The multivariable Cox proportional hazards regression model was applied to investigate the hazard ratio (HR) and 95% confidence interval (CI) for risk of pyogenic liver abscess associated with appendectomy and other comorbidities including alcoholism, biliary stone, chronic kidney disease, chronic liver diseases, and diabetes mellitus.The overall incidence of pyogenic liver abscess was 1.73-fold greater in the appendectomy group than that in the nonappendectomy group (3.85 vs 2.22 per 10,000 person-years, 95% CI 1.71, 1.76). The multivariable regression analysis disclosed that the adjusted HR of pyogenic liver abscess was 1.77 for the appendectomy group (95% CI 1.59, 1.97), when compared with the nonappendectomy group.Appendectomy is associated with increased hazard of pyogenic liver abscess. Further studies remain necessary to confirm our findings.

The Link between the Appendix and Ulcerative Colitis: Clinical Relevance and Potential Immunological Mechanisms

The human appendix has long been considered as a vestigial organ, an organ that has lost its function during evolution. In recent years, however, reports have emerged that link the appendix to numerous immunological functions in humans. Evidence has been presented for an important role of the appendix in maintaining intestinal health. This theory suggests that the appendix may be a reservoir or 'safe house' from which the commensal gut flora can rapidly be reestablished if it is eradicated from the colon. However, the appendix may also have a role in the development of inflammatory bowel disease (IBD). Several large epidemiological cohort studies have demonstrated the preventive effect of appendectomy on the development of ulcerative colitis, a finding that has been confirmed in murine colitis models. In addition, current studies are examining the possible therapeutic effect of an appendectomy to modulate disease course in patients with ulcerative colitis. This literature review assesses the current knowledge about the clinical and immunological aspects of the vermiform appendix in IBD and suggests that the idea of the appendix as a vestigial remnant should be discarded.

Innate immunity underlies symbiotic relationships

Here, the modern data regarding interactions between normal microbiota and barrier tissues in plants, humans and animals are reviewed. The main homeostatic mechanisms responsible for interactions between epithelium and innate immune cells with symbiotic bacteria are described. A key step in this process is recognition of soluble microbial products by ligation to pattern-recognition receptors expressed on the host cells. As a result, epithelial cells secrete mucus, antibacterial peptides and immunoregulatory molecules. The main outcomes from immunological reactions towards symbiotic bacteria involve development of conditions for formation and maintenance of microbial biocenosis as well as providing safety for the host. Also, it is considered important to preserve and transfer beneficial bacteria to progeny.

Medical models and metaphors for depression

BACKGROUND

The aetiology of depression is not fully understood, which allows many different perspectives on aetiology to be adopted. Researchers and clinicians may be attracted to concepts of aetiology that parallel other diagnoses with which they are familiar. Such parallels may assume the role of informal models or metaphors for depressive disorders. They may even function as informal scientific theories of aetiology, energising research activities by guiding hypothesis generation and organising new knowledge. Parallels between different types of disease may ultimately prove valuable as frameworks supporting the emergence and maturation of new knowledge. However, such models may be counterproductive if their basis, which is likely to lay at least partially in analogy, is unacknowledged or overlooked. This could cause such models to appear more compelling than they really are. Listing examples of situations in which models of depression may arise from, or be strengthened by, parallels to other familiar conditions may increase the accessibility of such models either to criticism or support. However, such a list has not yet appeared in the literature. The present paper was written with the modest goal of stating several examples of models or metaphors for depression.

METHOD

This paper adopted narrative review methods. The intention was not to produce a comprehensive list of such ideas, but rather to identify prominent examples of ways of thinking about depression that may have been invigorated as a result parallels with other types of disease.

RESULTS

Eight possible models are identified: depressive disorders as chemical imbalances (e.g., a presumed or theoretical imbalance of normally balanced neurotransmission in the brain), degenerative conditions (e.g., a brain disease characterised by atrophy of specified brain structures), toxicological syndromes (a result of exposure to a noxious psychological environment), injuries (e.g., externally induced brain damage related to stress), deficiency states (e.g., a serotonin deficiency), an obsolete category (e.g., similar to obsolete terms such as 'consumption' or 'dropsy'), medical mysteries (e.g., a condition poised for a paradigm-shifting breakthrough) or evolutionary vestiges (residual components of once adaptive mechanisms have become maladaptive in modern environments).

CONCLUSIONS

Conceptualisation of depressive disorders may be partially shaped by familiar disease concepts. Analogies of this sort may ultimately be productive (e.g., through generating hypotheses by analogy) or destructive (e.g., by structuring knowledge in incorrect, but intellectually seductive, ways).

Risk of new-onset type II diabetes after appendicectomy

BACKGROUND

Altered immune function after appendicectomy has been associated with autoimmune disease, even though the mechanisms are not clearly elucidated. This study aimed to investigate whether the frequency of new-onset type II diabetes was increased after appendicectomy in a case-control study.

METHODS

This was a retrospective cohort study from the Taiwan Longitudinal Health Insurance Database 2000. The relative risk was compared with that in the general population using population-based data. Each patient was tracked for a 3-year interval to identify those who developed type II diabetes. Cox proportional hazard regression analysis was used to assess the risk of type II diabetes during follow-up.

RESULTS

A total of 31,512 patients were included in the study, of whom 5252 had an appendicectomy (study cohort) and 26,260 were matched for comparison. Some 714 patients (2.3 per cent) developed type II diabetes during the 3-year follow-up, 161 in the study cohort (3.1 per cent) and 553 in the comparison cohort (2.1 per cent). The adjusted hazard ratio (HR) for type II diabetes in the study cohort was 1.45 (95 per cent c.i. 1.22 to 1.74). This increased risk was most pronounced in men (adjusted HR 1.47, 1.16 to 1.88) and in those with a perforated appendix (adjusted HR 2.28, 1.71 to 3.03), and applied only to patients younger than 65 years of age.

CONCLUSION

An increased risk of new-onset type II diabetes within 3 years after appendicectomy was found in patients aged less than 65 years. The risk was highest in men and in those with complicated appendicitis.

An appendectomy increases the risk of rheumatoid arthritis: a five-year follow-up study

Many studies have reported a possible association of an appendectomy with rheumatoid arthritis (RA). However, findings of the relationship between an appendectomy and RA remain inconsistent. Furthermore, all such studies were conducted in Western societies, and relevant studies on the relationship between an appendectomy and RA in Asian countries are still lacking. In this study, we investigated the relationship between an appendectomy and the subsequent risk of RA using a population-based dataset. We retrieved data for this retrospective cohort study from the Taiwan "Longitudinal Health Insurance Database 2005". We included 4,294 subjects who underwent an appendectomy in the study cohort and 12,882 matched subjects in the comparison cohort. We individually tracked each subject for a 5-year period from their index date to identify those who developed RA. A stratified Cox proportional hazard regression was performed to calculate the hazard ratio (HR) and its corresponding 95% confidence interval (CI) for the subsequent development of RA during the 5-year follow-up period between subjects who underwent an appendectomy and comparison subjects. Of the sampled subjects, 93 (0.54%) received a diagnosis of RA during the 5-year follow-up period: 33 from the study cohort (0.77% of subjects who underwent an appendectomy) and 60 from the comparison cohort (0.47% of comparison subjects) (p<0.001). After censoring individuals who died during the follow-up period and adjusting for subjects' monthly income and geographic region, the HR of RA during the 5-year follow-up period was 1.61 (95% CI = 1.05~2.48) for subjects who underwent an appendectomy compared to comparison subjects. We found that among females, the adjusted HR of RA was 1.76 (95% CI = 1.04~2.96) for subjects who underwent an appendectomy compared to comparison subjects. However, there was no increased hazard of RA for males who underwent an appendectomy compared to comparison subjects. We concluded that female subjects who undergo an appendectomy have a higher risk of RA than comparison female subjects.

Appendicitis as an early manifestation of subsequent malignancy: an asian population study

BACKGROUND & AIMS

Cancer risk after appendectomy in patients with appendicitis remains unclear. This study examined the role of appendicitis as an early manifestation harbingering the distant malignancy.

METHODS

From the insurance claims data of Taiwan, we identified a cohort of 130,374 patients newly received appendectomy from 2000-2009, without cancer diagnosis. A comparison cohort of 260,746 persons without appendectomy and cancer was selected from the same database, frequency matched by age, sex, comorbidity and index year. We monitored subsequent cancers with a12-month follow-up.

RESULTS

Over all, 1406 and 616 cancer cases were identified in the appendectomy cohort and comparisons, respectively, with all cancers incidence rate 4.64-fold higher in the appendectomy cohort (9.06 vs. 1.96 per 1000 person-months). Digestive and female genital organs harbored 80.9% of cancer cases in the appendectomy cohort. The Cox model measured site-specific hazard ratio (HR) was the highest for female genital cancers (23.3), followed by cancers of colorectum (14.7), small intestine (10.1), pancreas (7.40), lymphoma (5.89) and urinary system (4.50), all significant at 0.001 level. The HR of all cancers decreased from 13.7 within 3 months after appendectomy to 1.37 in 7-12 months after the surgery. In general, relative to the comparison cohort, younger appendectomy patients tended to have a higher HR than older patients.

CONCLUSIONS

The high incident cancers identified soon after appendectomy suggest the acute appendicitis is the early sign of distant metastatic malignancy. The risk of colorectal cancer, female genital cancer and haemopoietic malignancy deserve attention.