Metabolism of Maillard reaction products by the human gut microbiota - implications for health

The human colonic microbiota imparts metabolic versatility on the colon, interacts at many levels in healthy intestinal and systemic metabolism, and plays protective roles in chronic disease and acute infection. Colonic bacterial metabolism is largely dependant on dietary residues from the upper gut. Carbohydrates, resistant to digestion, drive colonic bacterial fermentation and the resulting end products are considered beneficial. Many colonic species ferment proteins but the end products are not always beneficial and include toxic compounds, such as amines and phenols. Most components of a typical Western diet are heat processed. The Maillard reaction, involving food protein and sugar, is a complex network of reactions occurring during thermal processing. The resultant modified protein resists digestion in the small intestine but is available for colonic bacterial fermentation. Little is known about the fate of the modified protein but some Maillard reaction products (MRP) are biologically active by, e.g. altering bacterial population levels within the colon or, upon absorption, interacting with human disease mechanisms by induction of inflammatory responses. This review presents current understanding of the interactions between MRP and intestinal bacteria. Recent scientific advances offering the possibility of elucidating the consequences of microbe-MRP interactions within the gut are discussed.

Upregulation of Oxidative Stress Markers in Human Microvascular Endothelial Cells by Complexes of Serum Albumin and Digestion Products of Glycated Casein

The extent of absorption of dietary advanced glycation end products (AGEs) is not fully known. The possible physiological impact of these absorbed components on inflammatory processes has been studied little and was the aim of this investigation. Aqueous solutions of bovine casein and glucose were heated at 95 degrees C for 5 h to give AGE-casein (AGE-Cas). Simulated stomach and small intestine digestion of AGE-Cas and dialysis (molecular mass cutoff of membrane = 1 kDa) resulted in a low molecular mass (LMM) fraction of digestion products, which was used to prepare bovine serum albumin (BSA)-LMM-AGE-Cas complexes. Stimulation of human microvascular endothelial cells with BSA-LMM-AGE-Cas complexes significantly increased mRNA expression of the receptor of AGE (RAGE), galectin-3 (AGE-113), tumor necrosis factor alpha, and a marker of the mitogen-activated protein kinase pathway (MAPK-1), as well as p65NF-kappa B activation. Cells treated with LMM digestion products of AGE-Cas significantly increased AGE-R3 mRNA expression. Intracellular reactive oxygen species production increased significantly in cells challenged with BSA-LMM-AGE-Cas and LMM-AGE-Cas. In conclusion, in an in vitro cell system, digested dietary AGEs complexed with serum albumin play a role in the regulation of RAGE and down-stream inflammatory pathways. AGE-R3 may protect against these effects.

Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea : Ancyrocephalidae)

Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron-dense (DED) secretory bodies with a homogenous electron-dense rind and a less electron-dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron-dense spherical bodies. Small, oval, electron-dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice-like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net-like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net-like structures. Based on this, it is postulated that the net-like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues.

Effective monitoring for ractopamine residues in samples of animal origin by SPR biosensor and mass spectrometry

Ractopamine (RCT) is a member of the beta-2-agonist (beta-agonist) family. It is licensed for use as an animal growth promoter in more than 20 countries worldwide, including the United States and Canada, but is either not licensed or prohibited by over 150 others, including those within the European Union. The issue of the use of RCT in livestock bound for human consumption has risen to prominence recently following the decision by The People's Republic of China to ban the import of pork from a number of processing plants after finding traces of RCT in shipments from the U.S.A.

Hyperglycaemia-induced pro-inflammatory responses by retinal Müller glia are regulated by the receptor for advanced glycation end-products (RAGE)

Aims/hypothesis: Up-regulation of the receptor for AGEs (RAGE) and its ligands in diabetes has been observed in various tissues. Here, we sought to determine levels of RAGE and one of its most important ligands, S100B, in diabetic retina, and to investigate the regulatory role of S100B and RAGE in Müller glia.

Methods: Streptozotocin-diabetes was induced in Sprague-Dawley rats. RAGE, S100B and glial fibrillary acidic protein (GFAP) were detected in retinal cryosections. In parallel, the human retinal Müller cell line, MIO-M1, was maintained in normal glucose (5.5 mmol/l) or high glucose (25 mmol/l). RAGE knockdown was achieved using small interfering RNA (siRNA), while soluble RAGE was used as a competitive inhibitor of RAGE ligand binding. RAGE, S100B and cytokines were detected using quantitative RT-PCR, western blotting, cytokine protein arrays or ELISA. Activation of mitogen-activated protein kinase (MAPK) by RAGE was determined by western blotting.

Results: Compared with non-diabetic controls, RAGE and S100B were significantly elevated in the diabetic retina with apparent localisation in the Müller glia, occurring concomitantly with upregulation of GFAP. Exposure of MIO-M1 cells to high glucose induced increased production of RAGE and S100B. RAGE signalling via MAPK pathway was linked to cytokine production. Blockade of RAGE prevented cytokine responses induced by high glucose and S100B in Müller glia.

Conclusions/interpretation: Hyperglycaemia in vivo and in vitro exposure to high glucose induce upregulation of RAGE and its ligands, leading to RAGE signalling, which links to pro-inflammatory responses by retinal Müller glia. These data shed light on the potential clinical application of RAGE blockade to inhibit the progression of diabetic retinopathy.

Profiling excretory/secretory proteins of Trichinella spiralis muscle larvae by two-dimensional gel electrophoresis and mass spectrometry

Infection of mammalian skeletal muscle with the intracellular parasite Trichinella spiralis results in profound alterations in the host cell and a realignment of host cell gene expression. The role of parasite excretory/secretory (E/S) products in mediating these effects is unknown, largely due to the difficulty in identifying and assigning function to individual proteins. In this study, we have used two-dimensional electrophoresis to analyse the profile of muscle larva excreted/secreted proteins and have coupled this to protein identification using MALDI-TOF mass spectrometry. Interpretation of the peptide mass fingerprint data has relied primarily on the interrogation of a custom-made Trichinella EST database and the NemaGene cluster database for T. spiralis. Our results suggest that this proteomic approach is a useful tool to study protein expression in Trichinella spp. and will contribute to the identification of excreted/secreted proteins.

Patterns of use of natural health products by Ontario seniors

A random dialing telephone survey of 1,071 60+ year-olds in 4 Ontario communities identified 553 (52%) users of natural health products. Mean age was 72 yrs (min-max:60-95); 76% were female. The most frequently reported natural health products were: echinacea (27%), glucosamine (26%), garlic (20%), ginkgo biloba (10%), St. John's wort (5%), ginseng (5%), flax seed oil (3%), evening primrose oil (2%), devil's claw (2%), saw palmetto (2%). Natural source vitamin use was reported by 24% of users, and 6% reporting using herbal teas. 51% of users used 2 or more herbal products and 8% used 5 or more products. 19% of herbal users also used a conventional prescription drug to manage the same health problem as the herbal product. The reported range of monthly expenditures for these products varied from a few cents (grew their own) to $288 (CAN). Thirty-five percent of users did not know the price of at least one of their natural products. Of the 75% of respondents willing to disclose their annual household income ($CAN), 20 had an income of $46,000. The widespread use and potential for significant expenditure of limited resources would suggest that more study is required into the efficacy, safety and value of these products.

The use of natural health products (NHP) by Ontario seniors

A random dialing telephone survey in 4 Ontario communities obtained data on the use of natural health products (NHP) from 1,071 persons 60 years and older. 553 (52%) respondents were users of NHP. Prevalence of use was similar for females (53%) and males (48%). In this population modal users were of European descent, high school graduates and employed at least part-time. Half the users received recommendations about NHP from friends or relatives; another 22% learned about NHP through self-experimentation. Most users (81 %) decided by themselves whether they would buy an NHP rather than rely on input from another source (herbalist, physician, store owner/employee). 38% of NHP users had not informed their physician that they were using an NHP. When users had discussed NHP with their physician, less than 5% of physicians responded negatively. Some users felt natural health products were safer (15%) and less expensive (4%) than prescription drugs. 30% used NHP as a last resort for the treatment of a chronic disease. Nearly half (49%) of the users believed that if the government pays for prescription drugs, it should also pay for herbal remedies; 36% said the consumer should pay. In light of the extensive use of NHP by seniors, there is a need for clinical pharmacology studies of these products.

Substrates modified by advanced glycation end-products cause dysfunction and death in retinal pericytes by reducing survival signals mediated by platelet-derived growth factor

AIMS/HYPOTHESIS: Premature death of retinal pericytes is a pathophysiological hallmark of diabetic retinopathy. Among the mechanisms proposed for pericyte death is exposure to AGE, which accumulate during diabetes. The current study used an in vitro model, whereby retinal pericytes were exposed to AGE-modified substrate and the mechanisms underlying pericyte death explored. METHODS: Pericytes were isolated from bovine retinal capillaries and propagated on AGE-modified basement membrane (BM) extract or non-modified native BM. The extent of AGE modification was analysed. Proliferative responses of retinal pericytes propagated on AGE-modified BM were investigated using a 5-bromo-2-deoxy-uridine-based assay. The effect of extrinsically added platelet-derived growth factor (PDGF) isoforms on these proliferative responses was also analysed alongside mRNA expression of the PDGF receptors. Apoptotic death of retinal pericytes grown on AGE-modified BM was investigated using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling labelling, mitochondrial membrane depolarisation and by morphological assessment. We also measured both the ability of PDGF to reverse Akt dephosphorylation that was mediated by AGE-modified BM, and increased pericyte apoptosis. RESULTS: Retinal pericytes exposed to AGE-modified BM showed reduced proliferative responses in comparison to controls (p

PESSTO: Survey description and products from the first data release by the Public ESO Spectroscopic Survey of Transient Objects

Context. The Public European Southern Observatory Spectroscopic Survey of Transient Objects (PESSTO) began as a public spectroscopic survey in April 2012. PESSTO classifies transients from publicly available sources and wide-field surveys, and selects science targets for detailed spectroscopic and photometric follow-up. PESSTO runs for nine months of the year, January - April and August - December inclusive, and typically has allocations of 10 nights per month. 

Aims. We describe the data reduction strategy and data products that are publicly available through the ESO archive as the Spectroscopic Survey data release 1 (SSDR1). 

Methods. PESSTO uses the New Technology Telescope with the instruments EFOSC2 and SOFI to provide optical and NIR spectroscopy and imaging. We target supernovae and optical transients brighter than 20.5^m for classification. Science targets are selected for follow-up based on the PESSTO science goal of extending knowledge of the extremes of the supernova population. We use standard EFOSC2 set-ups providing spectra with resolutions of 13-18 Å between 3345-9995 Å. A subset of the brighter science targets are selected for SOFI spectroscopy with the blue and red grisms (0.935-2.53 μm and resolutions 23-33 Å) and imaging with broadband JHK<inf>s</inf> filters. 

Results. This first data release (SSDR1) contains flux calibrated spectra from the first year (April 2012-2013). A total of 221 confirmed supernovae were classified, and we released calibrated optical spectra and classifications publicly within 24 h of the data being taken (via WISeREP). The data in SSDR1 replace those released spectra. They have more reliable and quantifiable flux calibrations, correction for telluric absorption, and are made available in standard ESO Phase 3 formats. We estimate the absolute accuracy of the flux calibrations for EFOSC2 across the whole survey in SSDR1 to be typically ∼15%, although a number of spectra will have less reliable absolute flux calibration because of weather and slit losses. Acquisition images for each spectrum are available which, in principle, can allow the user to refine the absolute flux calibration. The standard NIR reduction process does not produce high accuracy absolute spectrophotometry but synthetic photometry with accompanying JHK<inf>s</inf> imaging can improve this. Whenever possible, reduced SOFI images are provided to allow this. 

Conclusions. Future data releases will focus on improving the automated flux calibration of the data products. The rapid turnaround between discovery and classification and access to reliable pipeline processed data products has allowed early science papers in the first few months of the survey.