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Concept: Defecation


The safe disposal of human excreta is of paramount importance for the health and welfare of populations living in low income countries as well as the prevention of pollution to the surrounding environment. On-site sanitation (OSS) systems are the most numerous means of treating excreta in low income countries, these facilities aim at treating human waste at source and can provide a hygienic and affordable method of waste disposal. However, current OSS systems need improvement and require further research and development. Development of OSS facilities that treat excreta at, or close to, its source require knowledge of the waste stream entering the system. Data regarding the generation rate and the chemical and physical composition of fresh feces and urine was collected from the medical literature as well as the treatability sector. The data were summarized and statistical analysis was used to quantify the major factors that were a significant cause of variability. The impact of this data on biological processes, thermal processes, physical separators, and chemical processes was then assessed. Results showed that the median fecal wet mass production was 128 g/cap/day, with a median dry mass of 29 g/cap/day. Fecal output in healthy individuals was 1.20 defecations per 24 hr period and the main factor affecting fecal mass was the fiber intake of the population. Fecal wet mass values were increased by a factor of 2 in low income countries (high fiber intakes) in comparison to values found in high income countries (low fiber intakes). Feces had a median pH of 6.64 and were composed of 74.6% water. Bacterial biomass is the major component (25-54% of dry solids) of the organic fraction of the feces. Undigested carbohydrate, fiber, protein, and fat comprise the remainder and the amounts depend on diet and diarrhea prevalence in the population. The inorganic component of the feces is primarily undigested dietary elements that also depend on dietary supply. Median urine generation rates were 1.42 L/cap/day with a dry solids content of 59 g/cap/day. Variation in the volume and composition of urine is caused by differences in physical exertion, environmental conditions, as well as water, salt, and high protein intakes. Urine has a pH 6.2 and contains the largest fractions of nitrogen, phosphorus, and potassium released from the body. The urinary excretion of nitrogen was significant (10.98 g/cap/day) with urea the most predominant constituent making up over 50% of total organic solids. The dietary intake of food and fluid is the major cause of variation in both the fecal and urine composition and these variables should always be considered if the generation rate, physical, and chemical composition of feces and urine is to be accurately predicted.

Concepts: Protein, Nutrition, Urine, Organic compound, Nitrogen, Constipation, Uric acid, Defecation


Constipation and symptoms of gastrointestinal discomfort such as bloating are common among otherwise healthy individuals, but with significant impact on quality of life. Despite the recognized contribution of the gut microbiome to this pathology, little is known about which group(s) of microorganism(s) are playing a role. A previous study performed in vitro suggests that EpiCor® fermentate has prebiotic-like properties, being able to favorably modulate the composition of the gut microbiome. Therefore, the aim of this study was to investigate the effects of EpiCor fermentate in a population with symptoms of gastrointestinal discomfort and reduced bowel movements and to evaluate its effect at the level of the gut microbiome.

Concepts: Effect, Digestive system, Symptoms, Constipation, Gastroenterology, Learning, Defecation


The appendix may modulate colon microbiota and bowel inflammation. We investigated whether appendectomy alters colorectal cancer risk.

Concepts: Cancer, Colorectal cancer, Ulcerative colitis, Crohn's disease, Colon, Constipation, Large intestine, Defecation


Animals discharge feces within a range of sizes and shapes. Such variation has long been used to track animals as well as to diagnose illnesses in both humans and animals. However, the physics by which feces are discharged remain poorly understood. In this combined experimental and theoretical study, we investigate the defecation of mammals from cats to elephants using the dimensions of large intestines and feces, videography at Zoo Atlanta, cone-on-plate rheological measurements of feces and mucus, and a mathematical model of defecation. The diameter of feces is comparable to that of the rectum, but the length is double that of the rectum, indicating that not only the rectum but also the colon is a storage facility for feces. Despite the length of rectum ranging from 4 to 40 cm, mammals from cats to elephants defecate within a nearly constant duration of 12 ± 7 seconds (N = 23). We rationalize this surprising trend by our mathematical model, which shows that feces slide along the large intestine by a layer of mucus, similar to a sled sliding down a chute. Larger animals have not only more feces but also thicker mucus layers, which facilitate their ejection. Our model accounts for the shorter and longer defecation times associated with diarrhea and constipation, respectively. This study may support clinicians use of non-invasive procedures such as defecation time in the diagnoses of ailments of the digestive system.

Concepts: Digestive system, Colon, Constipation, Large intestine, Intestine, Small intestine, Digestion, Defecation


Smooth muscle sphincters exhibit basal tone and control passage of contents through organs such as the gastrointestinal tract; loss of this tone leads to disorders such as faecal incontinence. However, the molecular mechanisms underlying this tone remain unknown. Here, we show that deletion of myosin light-chain kinases (MLCK) in the smooth muscle cells from internal anal sphincter (IAS-SMCs) abolishes basal tone, impairing defecation. Pharmacological regulation of ryanodine receptors (RyRs), L-type voltage-dependent Ca(2+) channels (VDCCs) or TMEM16A Ca(2+)-activated Cl(-) channels significantly changes global cytosolic Ca(2+) concentration ([Ca(2+)]i) and the tone. TMEM16A deletion in IAS-SMCs abolishes the effects of modulators for TMEM16A or VDCCs on a RyR-mediated rise in global [Ca(2+)]i and impairs the tone and defecation. Hence, MLCK activation in IAS-SMCs caused by a global rise in [Ca(2+)]i via a RyR-TMEM16A-VDCC signalling module sets the basal tone. Targeting this module may lead to new treatments for diseases like faecal incontinence.

Concepts: Cardiac muscle, Actin, Stomach, Muscle contraction, Skeletal muscle, Muscular system, Defecation, Sphincter


: The purpose of this study was to identify patient, clinical, and surgical factors that may predispose patients to anastomotic leak (AL) after large bowel surgery.

Concepts: Colon, Defecation


OBJECTIVE.: Fecal incontinence reduces the quality of life of many women but has no long-term cure. Research on mesenchymal stem cell (MSC)-based therapies has shown promising results. The primary aim of this study was to evaluate functional recovery after treatment with MSCs in two animal models of anal sphincter injury. METHODS.: Seventy virgin female rats received a sphincterotomy (SP) to model episiotomy, a pudendal nerve crush (PNC) to model the nerve injuries of childbirth, a sham SP, or a sham PNC. Anal sphincter pressures and electromyography (EMG) were recorded after injury but before treatment and 10days after injury. Twenty-four hours after injury, each animal received either 0.2ml saline or 2million MSCs labelled with green fluorescing protein (GFP) suspended in 0.2ml saline, either intravenously (IV) into the tail vein or intramuscularly (IM) into the anal sphincter. RESULTS.: MSCs delivered IV after SP resulted in a significant increase in resting anal sphincter pressure and peak pressure, as well as anal sphincter EMG amplitude and frequency 10days after injury. MSCs delivered IM after SP resulted in a significant increase in resting anal sphincter pressure and anal sphincter EMG frequency but not amplitude. There was no improvement in anal sphincter pressure or EMG with in animals receiving MSCs after PNC. GFP-labelled cells were not found near the external anal sphincter in MSC-treated animals after SP. CONCLUSION.: MSC treatment resulted in significant improvement in anal pressures after SP but not after PNC, suggesting that MSCs could be utilized to facilitate recovery after anal sphincter injury.

Concepts: Stem cell, Mesenchymal stem cell, Bone marrow, Stem cells, Adipocyte, Mesenchyme, Defecation, Sphincter


BACKGROUND: The aim of our study was to evaluate gas retention, abdominal symptoms and changes in girth circumference in females with bloating using an active or sham abdominal wall mechanical stimulation. METHODS: In 14 female patients, complaining of bloating (11 with irritable bowel syndrome and 3 with functional bloating according to the Rome III criteria) a gas mixture was continuously infused into the colon for 1 h (accommodation period). Abdominal perception and girth were measured. At the beginning of the 30-min period of free rectal gas evacuation (clearance period), an electromechanical device was positioned on the abdominal wall of all patients. The patients were randomly assigned to an active or a sham stimulation protocol group. Gas retention, perception and abdominal distension were measured at the end of the clearance period. RESULTS: All patients tolerated the volume (1,440 ml) of gas infused into the colon. Abdominal perception and girth measurements was similar in both groups during the accommodation period. At the end of the clearance, the perception score and the girth changes in the active and sham stimulation groups were similar (2.8 ± 2.0 vs. 1.4 ± 1.2, p = 0.2 and 4.9 ± 4.5 vs. 2.8 ± 2.3 mm, p = 0.3 active vs. sham, respectively). Furthermore, the mechanical stimulation of the abdominal wall did not significantly reduce gas retention (495 ± 101 ml vs. 566 ± 55, active vs. sham, p = 0.1). CONCLUSIONS: An external mechanical massage of the abdominal wall did not improve intestinal gas transit, abdominal perception and abdominal distension in our female patients complaining of functional bloating.

Concepts: Abdominal pain, Constipation, Intestine, Gastroenterology, Irritable bowel syndrome, Flatulence, Defecation, Abdominal distension


Limited literature exists on whether slow colonic transit adversely influences the results of outlet obstruction surgery. We compared the functional results of laparoscopic ventral rectopexy (LVR) for obstructed defecation secondary to high grade internal rectal prolapse in patients with normal and slow colonic transit.

Concepts: Surgery, Colon, High school, Rectum, Defecation, Prolapse, Rectal prolapse, Anus


BACKGROUND/AIMS: Chronic constipation is frequently seen in women who have undergone hysterectomy or delivery. However, reports regarding anorectal physiologic features in those patients are rare. We analyzed the constipated patients associated with either radical hysterectomy or vaginal delivery in order to clarify the anorectal physiologic features and the effectiveness of biofeedback therapy. METHODS: Of the constipated patients, we included a hysterectomy group (n=40), delivery group (n=41), and a control group (n=89), who had no history of either surgery or delivery before developing functional constipation. We investigated their anorectal physiological tests and the effectiveness of biofeedback therapy. RESULTS: The volume of desire to defecate was greater in the hysterectomy group than in the control group (86.5±55.0 mL vs. 62.9±33.7 mL; P=0.03), and more than 240 ml of maximal volume of toleration was more frequently noted in the hysterectomy group (32.5%) than in the delivery group (14.6%) and control group (13.5%) (P=0.02).The failure of balloon expulsion was more frequently noted in delivery group (44.0%) than in the hysterectomy group (15.0%) and control group (25.0%) (P=0.01). The defecation satisfaction score was significantly increased after biofeedback therapy in the hysterectomy group (2.0 ± 2.7 vs. 7.8 ± 1.5, P<0.001), the delivery group (1.6 ± 2.1 vs. 6.7 ± 2.0, P<0.001) and the control group (2.5 ± 2.7 vs. 6.9 ± 2.1, P<0.001). CONCLUSIONS: Rectal hyposensitivity could have been the characteristic mechanism in the hysterectomy group, whereas dyssynergic defecation could have been the cause in the delivery group. Biofeedback therapy was effective for both groups.

Concepts: Childbirth, Physiology, Colon, Constipation, Dietary fiber, Rectum, Defecation, Anismus