Plant cell walls: impact on nutrient bioaccessibility and digestibility

Cell walls are important structural components of plants, affecting both the bioaccessibility and subsequent digestibility of the nutrients that plant-based foods contain. These supramolecular structures are composed of complex heterogeneous networks primarily consisting of cellulose, and hemicellulosic and pectic polysaccharides. The composition and organization of these different polysaccharides vary depending on the type of plant tissue, imparting them with specific physicochemical properties. These properties dictate how the cell walls behave in the human gastrointestinal tract, and how amenable they are to digestion, thereby modulating nutrient release from the plant tissue. This short narrative review presents an overview of our current knowledge on cell walls and how they impact nutrient bioaccessibility and digestibility. Some of the most relevant methods currently used to characterize the food matrix and the cell walls are also described

TAIR: A transonic airfoil analysis computer code

The operation of the TAIR (Transonic AIRfoil) computer code, which uses a fast, fully implicit algorithm to solve the conservative full-potential equation for transonic flow fields about arbitrary airfoils, is described on two levels of sophistication: simplified operation and detailed operation. The program organization and theory are elaborated to simplify modification of TAIR for new applications. Examples with input and output are given for a wide range of cases, including incompressible, subcritical compressible, and transonic calculations

Identification of a quorum sensing-dependent communication pathway mediating bacteria-gut-brain cross talk

Despite recently established contributions of the intestinal microbiome to human health and disease, our understanding of bacteria-host communication pathways with regard to the gut-brain axis remains limited. Here we provide evidence that intestinal neurons are able to “sense” bacteria independently of the host immune system. Using supernatants from cultures of the opportunistic pathogen Staphylococcus aureus (S. aureus) we demonstrate the release of mediators with neuromodulatory properties at high population density. These mediators induced a biphasic response in extrinsic sensory afferent nerves, increased membrane permeability in cultured sensory neurons, and altered intestinal motility and secretion. Genetic manipulation of S. aureus revealed two key quorum sensing-regulated classes of pore forming toxins that mediate excitation and inhibition of extrinsic sensory nerves, respectively. As such, bacterial mediators have the potential to directly modulate gut-brain communication to influence intestinal symptoms and reflex function in vivo, contributing to homeostatic, behavioral, and sensory consequences of infection

Liver Transplantation to Provide Low-Density-Lipoprotein Receptors and Lower Plasma Cholesterol in a Child with Homozygous Familial Hypercholesterolemia

A six-year-old girl with severe hypercholesterolemia and atherosclerosis had two defective genes at the low-density-lipoprotein (LDL) receptor locus, as determined by biochemical studies of cultured fibroblasts. One gene, inherited from the mother, produced no LDL receptors; the other gene, inherited from the father, produced a receptor precursor that was not transported to the cell surface and was unable to bind LDL. The patient degraded intravenously administered 125I-LDL at an extremely low rate, indicating that her high plasma LDL-cholesterol level was caused by defective receptor-mediated removal of LDL from plasma. After transplantation of a liver and a heart from a normal donor, the patient's plasma LDL-cholesterol level declined by 81 per cent, from 988 to 184 mg per deciliter. The fractional catabolic rate for intravenously administered 125I-LDL, a measure of functional LDL receptors in vivo, increased by 2.5-fold. Thus, the transplanted liver, with its normal complement of LDL receptors, was able to remove LDL cholesterol from plasma at a nearly normal rate. We conclude that a genetically determined deficiency of LDL receptors can be largely reversed by liver transplantation. These data underscore the importance of hepatic LDL receptors in controlling the plasma level of LDL cholesterol in human beings. (N Engl J Med 1984; 311: 1658–64.). © 1984, Massachusetts Medical Society. All rights reserved

Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia

BACKGROUND: There are no standard criteria for when to discontinue intravenous antimicrobial therapy (IVAMT) in children with febrile neutropenia (FN), but it is now common to discontinue IVAMT and discharge patients with an absolute neutrophil count (ANC) ≤ 500 /mm(3). The purpose of this study was to evaluate the outcome of a large cohort of children with FN who had IVAMT discontinued with an ANC ≤ 500 /mm(3) METHODS: A retrospective chart review was completed of patients in the Northern Alberta Children's Cancer Program with FN and no apparent clinical source of fever from June 1, 1997 to July 1, 2002. RESULTS: Out of a total of 275 patients, 127 (46%) had at least one episode of FN, with FN occurring in patients with sarcomas more commonly than in those with leukemia/ lymphoma and least in those with other solid tumors. In 59 of 276 episodes of FN (21%) patients had a microbiologically defined infection at admission. Of the 217 remaining episodes, 112 of 199 patients (56%) with known neutrophil counts had IVAMT discontinued before their absolute neutrophil count (ANC) reached 500 /mm(3 )at the discretion of the clinician. Fever recurred in only two of these patients after discharge, and there were no bacterial infections diagnosed after parenteral antibiotics were discontinued. CONCLUSION: Even without use of standard criteria for early discharge, clinicians appear to be skilled at selecting children with FN who can safely have IVAMT discontinued with an ANC ≤ 500 /mm(3)

The Indian Ocean tsunami: socio-economic impacts in Thailand

On the morning of 26 December 2004 large areas of coastal southern Thailand were transformed when a tsunami, generated by a powerful submarine earthquake in the Indian Ocean, swept ashore. Officially, there were 5395 confirmed deaths in Thailand with another 2932 people listed as missing. In February 2005 a team led by Dr Ben Horton of the University of Pennsylvania was awarded an SGER grant by the National Science Foundation to undertake exploratory research on the tsunami in Malaysia and Thailand. This report summarizes the preliminary conclusions of the social science element of the Thai fieldwork. The team undertook fieldwork in three main sites during July 2005: Koh Lanta, Koh Phi Phi and Khao Lak. We chose Koh Phi Phi as a small, tourist (backpacker)-oriented island economy with high levels of damage and casualties; Koh Lanta as a site with a significant population of fisherfolk with a long presence in the area; and Khao Lak as a mainland site with the highest number of casualties in Thailand and with a mixed tourism-fishing economy

The Albedo, Size, and Density of Binary Kuiper Belt Object (47171) 1999 TC36

We measured the system-integrated thermal emission of the binary Kuiper Belt Object 1999 TC36 at wavelengths near 24 and 70 microns using the Spitzer space telescope. We fit these data and the visual magnitude using both the Standard Thermal Model and thermophysical models. We find that the effective diameter of the binary is 405 km, with a range of 350 -- 470 km, and the effective visible geometric albedo for the system is 0.079 with a range of 0.055 -- 0.11. The binary orbit, magnitude contrast between the components, and system mass have been determined from HST data (Margot et al., 2004; 2005a; 2005b). Our effective diameter, combined with that system mass, indicate an average density for the objects of 0.5 g/cm3, with a range 0.3 -- 0.8 g/cm3. This density is low compared to that of materials expected to be abundant in solid bodies in the trans-Neptunian region, requiring 50 -- 75% of the interior of 1999 TC36 be taken up by void space. This conclusion is not greatly affected if 1999 TC36 is ``differentiated'' (in the sense of having either a rocky or just a non-porous core). If the primary is itself a binary, the average density of that (hypothetical) triple system would be in the range 0.4 -- 1.1 g/cm3, with a porosity in the range 15 -- 70%.Comment: ApJ, in press (May, 2006