Fibre and bowel transit times

Js, Gear; Aj, Brodribb; Ware, Adam L.; Ji, Mann

doi:10.1079/bjn19810078

Cited by 51 publications

(22 citation statements)

References 6 publications

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“…The lower bound is approximately 24 h, which is about as fast as the microbe can cycle through the intestinal track without colonization. [49][50][51] The upper bound is approximately 70 years, which is the longest period of colonization without cycling and corresponds favorably with the maximum life span of the host. 52 The optimum value for the cycle time, as determined by the optimum value for demand ͓from Figs.…”

Section: Life Cycle Provides the Context For Gene Controlmentioning

confidence: 99%

Design principles for elementary gene circuits: Elements, methods, and examples

Savageau

2001

Chaos: An Interdisciplinary Journal of Nonlinear Science

167

168

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The control of gene expression involves complex circuits that exhibit enormous variation in design. For years the most convenient explanation for these variations was historical accident. According to this view, evolution is a haphazard process in which many different designs are generated by chance; there are many ways to accomplish the same thing, and so no further meaning can be attached to such different but equivalent designs. In recent years a more satisfying explanation based on design principles has been found for at least certain aspects of gene circuitry. By design principle we mean a rule that characterizes some biological feature exhibited by a class of systems such that discovery of the rule allows one not only to understand known instances but also to predict new instances within the class. The central importance of gene regulation in modern molecular biology provides strong motivation to search for more of these underlying design principles. The search is in its infancy and there are undoubtedly many design principles that remain to be discovered. The focus of this three-part review will be the class of elementary gene circuits in bacteria. The first part reviews several elements of design that enter into the characterization of elementary gene circuits in prokaryotic organisms. Each of these elements exhibits a variety of realizations whose meaning is generally unclear. The second part reviews mathematical methods used to represent, analyze, and compare alternative designs. Emphasis is placed on particular methods that have been used successfully to identify design principles for elementary gene circuits. The third part reviews four design principles that make specific predictions regarding (1) two alternative modes of gene control, (2) three patterns of coupling gene expression in elementary circuits, (3) two types of switches in inducible gene circuits, and (4) the realizability of alternative gene circuits and their response to phased environmental cues. In each case, the predictions are supported by experimental evidence. These results are important for understanding the function, design, and evolution of elementary gene circuits. (c) 2001 American Institute of Physics.

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Section: Life Cycle Provides the Context For Gene Controlmentioning

confidence: 99%

Design principles for elementary gene circuits: Elements, methods, and examples

Savageau

2001

Chaos: An Interdisciplinary Journal of Nonlinear Science

167

168

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“…Stool frequency is impacted by an individual's health (see physical form section) as well as their fibre intake which is associated with more rapid transit times (Gear et al, 1981). Fibre intake has been positively correlated with stool frequency (r = 0.8, p < 0.001 wet weight; r = 0.5, p = 0.008 dry weight) (Southgate et al, 1976).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology

Rose

Parker

Jefferson

et al. 2015

Critical Reviews in Environmental Science and Technology

998

704

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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.

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“…53 Gear et al 54 also concluded that a high intake of dietary fibre is associated with more rapid transit times.…”

Section: Fibre and Constipationmentioning

confidence: 99%

LIFELAX – diet and LIFEstyle versus LAXatives in the management of chronic constipation in older people: randomised controlled trial

Speed

Heaven²,

Adamson³

et al. 2010

Health Technol Assess

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How to obtain copies of this and other HTA programme reports An electronic version of this title, in Adobe Acrobat format, is available for downloading free of charge for personal use from the HTA website (www.hta.ac.uk). A fully searchable DVD is also available (see below).Printed copies of HTA journal series issues cost £20 each (post and packing free in the UK) to both public and private sector purchasers from our despatch agents.Non-UK purchasers will have to pay a small fee for post and packing. For European countries the cost is £2 per issue and for the rest of the world £3 per issue. How to order:-fax (with credit card details) -post (with credit card details or cheque) -phone during office hours (credit card only).Additionally the HTA website allows you to either print out your order or download a blank order form. Contact details are as follows:Synergie UK (HTA Department) Digital House, The Loddon Centre Wade Road Basingstoke Hants RG24 8QW Email: orders@hta.ac.uk Tel: 0845 812 4000 -ask for 'HTA Payment Services' (out-of-hours answer-phone service) Fax: 0845 812 4001 -put 'HTA Order' on the fax header Payment methods Paying by chequeIf you pay by cheque, the cheque must be in pounds sterling, made payable to University of Southampton and drawn on a bank with a UK address. Paying by credit cardYou can order using your credit card by phone, fax or post. SubscriptionsNHS libraries can subscribe free of charge. Public libraries can subscribe at a reduced cost of £100 for each volume (normally comprising 40-50 titles). The commercial subscription rate is £400 per volume (addresses within the UK) and £600 per volume (addresses outside the UK). Please see our website for details. Subscriptions can be purchased only for the current or forthcoming volume. How do I get a copy of HTA on DVD?Please use the form on the HTA website (www.hta.ac.uk/htacd/index.shtml). HTA on DVD is currently free of charge worldwide.The website also provides information about the HTA programme and lists the membership of the various committees. HTA LIFELAX -diet and LIFEstyle versus Health Technology Assessment is indexed and abstracted in Index Medicus/MEDLINE, Excerpta Medica/EMBASE, Science Citation Index Expanded (SciSearch NIHR Health Technology Assessment programmeT he Health Technology Assessment (HTA) programme, part of the National Institute for Health Research (NIHR), was set up in 1993. It produces high-quality research information on the effectiveness, costs and broader impact of health technologies for those who use, manage and provide care in the NHS. 'Health technologies' are broadly defined as all interventions used to promote health, prevent and treat disease, and improve rehabilitation and long-term care. The research findings from the HTA programme directly influence decision-making bodies such as the National Institute for Health and Clinical Excellence (NICE) and the National Screening Committee (NSC). HTA findings also help to improve the quality of clinical practice in the NHS indirectly in that they form a ...

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Fibre and bowel transit times

Cited by 51 publications

References 6 publications

Design principles for elementary gene circuits: Elements, methods, and examples

Design principles for elementary gene circuits: Elements, methods, and examples

The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology

LIFELAX – diet and LIFEstyle versus LAXatives in the management of chronic constipation in older people: randomised controlled trial

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