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Retention marker excretion suggests incomplete digesta mixing across the order primates

Matsuda I, Espinosa-Gómez FC, Ortmann S, Sha JCM, Osman I, Nijboer J, et al.

Physiol Behav, 2019 09 01;208:112558.
PMID: 31125579 DOI: 10.1016/j.physbeh.2019.112558

The digestive tract of animals, and the patterns how passage markers are excreted from them, have been fruitfully compared to chemical reactor models from engineering science. An important characteristic of idealized reactor models is the smoothness of the curves plotting marker concentrations in outflow (i.e., faeces) over time, which is the result of the assumed complete mixing of the marker with the reactor contents. Published excretion patterns from passage experiments in non-primate mammals appear to indicate a high degree of digesta mixing. In order to assess whether marker excretion graphs from primates differ from ideal outflow graphs, we performed passage experiments in eight individuals of three foregut-fermenting species (Pygathrix nemaeus, Trachypithecus auratus and Semnopithecus vetulus), and added them to available marker excretion curves from the literature. In the resulting collection, 23 out of a total of 25 patterns in foregut fermenters (21 individuals of 10 species from 7 studies), and 13 out of 15 in hindgut fermenters (9 individuals of 2 species from 2 studies), showed an irregular, 'spiky' pattern. We consider this proportion to be too high to be explained by experimental errors, and suggest that this may indicate a taxon-wide characteristic of particularly incomplete digesta mixing, acknowledging that further data from less related primate species are required for corroboration. Our hypothesis is in accordance with previous findings of a comparatively low degree of 'digesta washing' (differential retention of particulate and fluid digesta) in primates. Together with literature findings that suggest a low chewing efficiency in primates compared to other mammals, these observations indicate that in contrast to other herbivores, the success of the primate order is not derived from particularly elaborate adaptations of their ingestive and digestive physiology.

Matched MeSH terms: Gastrointestinal Transit/physiology
'Rapid transit' constipation in children: a possible genesis for irritable bowel syndrome

Hutson JM, Hynes MC, Kearsey I, Yik YI, Veysey DM, Tudball CF, et al.

Pediatr Surg Int, 2020 Jan;36(1):11-19.
PMID: 31673760 DOI: 10.1007/s00383-019-04587-x

Children with chronic idiopathic constipation (CIC) often end up at the surgeon when medical treatments have failed. This opinion piece discusses a recently described pattern of CIC called 'Rapid transit constipation (RTC)' first identified in 2011 as part of surgical workup. RTC was identified using a nuclear medicine gastrointestinal transit study (NMGIT or nuclear transit study) to determine the site of slowing within the bowel and to inform surgical treatment. Unexpectedly, we found that RTC occured in 29% of 1000 transit studies in a retrospective audit. Irritable bowel syndrome (IBS) occurs in 7-21% of the population, with a higher prevalence in young children and with constipation type dominating in the young. While 60% improve with time, 40% continue with symptoms. First-line therapy for IBS in adults is a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols which reduces symptoms in > 70% of patients. In children with functional gastrointestinal disorders, fructose intolerance occurs in 35-55%. Reducing fructose produced significant improvement in 77-82% of intolerant patients. In children with RTC and a positive breath test upon fructose challenge, we found that exclusion of fructose significantly improved constipation, abdominal pain, stool consistency and decreased laxative use. We hypothesise that positive breath tests and improvement of pain and bowel frequency with sugar exclusion diets in RTC suggest these children have IBS-C. These observations raise the possibility that many children with CIC could be treated by reducing fructose early in their diet and this might prevent the development of IBS in later life.

Matched MeSH terms: Gastrointestinal Transit/physiology*
Gamma-scintigraphic study of the gastrointestinal transit and in vivo dissolution of a controlled release diclofenac sodium formulation in xanthan gum matrices

Billa N, Yuen KH, Khader MA, Omar A

Int J Pharm, 2000 May 15;201(1):109-20.
PMID: 10867269

A xanthan gum matrix controlled release tablet formulation containing diclofenac sodium was evaluated in vitro and was found to release the drug at a uniform rate. The gastrointestinal transit behaviour of the formulation as determined by gamma scintigraphy, using healthy male volunteers under fasted and fed conditions, indicated that gastric emptying was delayed with food intake. In contrast, the small intestinal transit remained practically unchanged under both food statuses. Therefore, the delay in caecal arrival observed in the fed state can be attributed to the delay in gastric emptying. Rate of diclofenac sodium absorption was generally higher in the fed state compared to the fasted state, however the total amount absorbed under both food statuses remained practically the same. The rate of in vivo dissolution of the drug in the fed state was faster compared to that in the fasted state. Thus, at the time of caecal arrival, in vivo dissolution was complete in the fed state, unlike in the fasted state, where almost 60% of the drug was delivered to the colon.

Matched MeSH terms: Gastrointestinal Transit/physiology*
Home-Based Transabdominal Interferential Electrical Stimulation for Six Months Improves Paediatric Slow Transit Constipation (STC)

Yik YI, Hutson J, Southwell B

Neuromodulation, 2018 Oct;21(7):676-681.
PMID: 29164818 DOI: 10.1111/ner.12734

BACKGROUND: Transcutaneous electrical stimulation (TES) for one to two months has produced some improvement in treatment-resistant slow-transit constipation (STC) in children. Optimal parameters for treatment are not known. It is possible that more improvement would occur with stimulation for longer. This study examined the effectiveness of stimulation for six months.
METHODS: Children with STC confirmed by nuclear transit study (NTS) were enrolled prospectively. All had chronic constipation for greater than two years and had failed medical treatment. TES was performed for one hour/day for six months using the INF 4160 (Fuji Dynamics) portable stimulator and 4 cm × 4 cm electrodes near the belly button and on the back. Families kept bowel diaries and completed PEDSQLCore QOL (4.0) questionnaires before and at end of treatment.
RESULTS: Sixty-two children (34 females; seven years, 2-16 year) with STC were studied. Defecation frequency increased in 57/62 (91%, mean ± SEM pre- 1.49 ± 0.20 vs. post- 3.25 ± 0.25 defecation/week, p transit index and gastric emptying on NTS improved (p

Matched MeSH terms: Gastrointestinal Transit/physiology