High ambient temperature has multiple potential effects on the organism such as hyperthermia, endotoxemia, and/or systemic inflammation. However, it is often difficult to discriminate between cause and consequence of phenotypic effects, such as the indirect influence of heat stress via reduced food intake. Lactating dairy cows are a particularly sensitive model to examine the effects of heat stress due to their intensive metabolic heat production and small surface:volume ratio. Results from this model show heat stress directly induced a so-far unknown infiltration of yet uncategorized cells into the mucosa and submucosa of the jejunum. Due to a pair-feeding design, we can exclude this effect being a consequence of the concurrent heat-induced reduction in feed intake. Isolation and characterization of the infiltrating cells using laser capture microdissection and RNA sequencing indicated a myeloic origin and macrophage-like phenotype. Furthermore, targeted transcriptome analyses provided evidence of activated immune- and phagocytosis-related pathways with LPS and cytokines as upstream regulators directly associated with heat stress. Finally, we obtained indication that heat stress may directly alter jejunal tight junction proteins suggesting an impaired intestinal barrier. The penetration of toxic and bacterial compounds during heat stress may have triggered a modulated immune repertoire and induced an antioxidative defense mechanism to maintain homeostasis between commensal bacteria and the jejunal immune system. Our bovine model indicates direct effects of heat stress on the jejunum of mammals already at moderately elevated ambient temperature. These results need to be considered when developing concepts to combat the negative consequences of heat stress.

P301L mutant tau transgenic mice develop neurofibrillary tangles, a histopathologic hallmark of Alzheimer's disease and frontotemporal dementia (FTDP-17). To identify differentially expressed genes and to gain insight into pathogenic mechanisms, we performed a stringent analysis of the microarray dataset obtained with RNA from whole brains of P301L mutant mice and identified a single up-regulated gene, glyoxalase I. This enzyme plays a critical role in the detoxification of dicarbonyl compounds and thereby reduces the formation of advanced glycation end products. In situ hybridization analysis revealed expression of glyoxalase I in all brain areas analyzed, both in transgenic and control mice. However, levels of glyoxalase I protein were significantly elevated in P301L brains, as shown by Western blot analysis and immunohistochemistry. Moreover, a glyoxalase I-specific antiserum revealed many intensely stained flame-shaped neurons in Alzheimer's disease brain compared with brains from nondemented controls. In addition, we examined a single nucleotide polymorphism predicting a nonconservative amino acid substitution at position 111 (E111A) in ethnically independent populations. We identified significant and consistent deviations from HardyWeinberg equilibrium, which points to the presence of selection forces. The E111A single nucleotide polymorphism was not associated with the risk for Alzheimer's disease in the overall population. Together, our data demonstrate the potential of transcriptomics applied to animal models of human diseases. They suggest a previously unidentified role for glyoxalase I in neurodegenerative disease. A lzheimer's disease (AD) and frontotemporal dementia are common forms of age-related dementing diseases. They are characterized by proteinaceous aggregates, which are resistant to proteolysis due to conformational changes and posttranslational modifications such as hyperphosphorylation and glycation (1-4). In AD, these aggregates are ␤-amyloid plaques and neurofibrillary tangles (NFT). NFT formation, in the absence of overt amyloid plaques, is found in a group of neurodegenerative diseases, including frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) (5, 6). In affected cells, the microtubule-associated protein tau is abnormally phosphorylated and relocalized from axonal to somatodendritic compartments, where it accumulates in aggregates that eventually assemble into NFT (7). The identification of mutations in the tau gene in FTDP-17 established that dysfunction of tau in itself can lead to dementia (6).NFT formation has been reproduced in transgenic mice by expression of FTDP-17 mutant tau, both in neurons (8-12) and in glial cells (13)(14)(15). Moreover, intracerebral injection of ␤-amyloid fibrils caused significant increases of NFT in the amygdala of P301L (FTDP-17) mutant mice (16). A similar increase was achieved by crossing ␤-amyloid-producing amyloid precursor protein mutant mice with P301L mice (17).The pathologic similarities between the P301L transgenic ...

In this immunohistochemical study, the age- and stage-dependent accumulation of advanced glycation end-products (AGEs) in Alzheimer's disease (AD) and their relation to the formation of neurofibrillary tangles and neuronal cell death was investigated. For this purpose, the distribution of AGEs in neurons and glia was analyzed in the auditory association area of superior temporal gyrus (Brodmann area 22) of young and old non-demented controls and compared with early- and late-stage AD. A possible co-localization of AGEs with typical hallmarks of AD, such as hyperphosphorylated tau (as a marker for disturbed kinase/phosphatase activity), nNOS (as a marker for nitroxidative stress) and caspase-3 (as a marker of apoptotic cell death), was also investigated. Our results show that the percentage of AGE-positive neurons (and astroglia) increase both with age and, in AD patients, with the progression of the disease (Braak stages). Interestingly, nearly all if those neurons which show diffuse cytosolic AGE immunoreactivity also contain hyperphosphoryated tau, suggesting a link between AGE accumulation and the formation of early neurofibrillary tangles. Many, but not all, neurons show a co-localization of AGEs with other markers of neurodegeneration, such as nNOS and caspase-3.

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The accumulation of advanced glycation end products (AGEs) in brains with Alzheimer's disease (AD) has been implicated in the formation of insoluble deposits such as amyloid plaques and neurofibrillary tangles. AGEs are also known to activate glia, resulting in inflammation and neuronal dysfunction. As reactive intermediates of AGE formation, neurotoxic reactive dicarbonyl compounds such as glyoxal and methylglyoxal have been identified. One of the most effective detoxification systems for methylglyoxal and glyoxal is the glutathione-dependent glyoxalase system, consisting of glyoxalase I and glyoxalase II. In this study, we have determined the methylglyoxal and glyoxal levels in the cerebrospinal fluid of AD patients compared to healthy controls. Methylglyoxal levels in AD patients were twofold higher than in controls, but this difference was not significant due to the large intergroup variations and the small sample size. However, the concentrations of both compounds were five to seven times higher in CSF than in plasma. We also investigated the glyoxalase I level in AD and healthy control brains. The number of glyoxalase I- positive neurons were increased in AD brains compared to controls. Our findings suggest that glyoxalase I is upregulated in AD in a compensatory manner to maintain physiological methylglyoxal and glyoxal levels.

Ruminant production systems are important contributors to anthropogenic methane (CH) emissions, but there are large uncertainties in national and global livestock CH inventories. Sources of uncertainty in enteric CH emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH emission factors. There is also significant uncertainty associated with enteric CH measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.

High ambient temperatures have severe adverse effects on biological functions of high-yielding dairy cows. The metabolic adaption to heat stress was examined in 14 German Holsteins transition cows assigned to two groups, one heat-stressed (HS) and one pair-fed (PF) at the level of HS. After 6 days of thermoneutrality and ad libitum feeding (P1), cows were challenged for 6 days (P2) by heat stress (temperature humidity index (THI) = 76) or thermoneutral pair-feeding in climatic chambers 3 weeks ante partum and again 3 weeks post-partum. On the sixth day of each period P1 or P2, oxidative metabolism was analyzed for 24 hours in open circuit respiration chambers. Water and feed intake, vital parameters and milk yield were recorded. Daily blood samples were analyzed for glucose, β-hydroxybutyric acid, non-esterified fatty acids, urea, creatinine, methyl histidine, adrenaline and noradrenaline. In general, heat stress caused marked effects on water homeorhesis with impairments of renal function and a strong adrenergic response accompanied with a prevalence of carbohydrate oxidation over fat catabolism. Heat-stressed cows extensively degraded tissue protein as reflected by the increase of plasma urea, creatinine and methyl histidine concentrations. However, the acute metabolic heat stress response in dry cows differed from early-lactating cows as the prepartal adipose tissue was not refractory to lipolytic, adrenergic stimuli, and the rate of amino acid oxidation was lower than in the postpartal stage. Together with the lower endogenous metabolic heat load, metabolic adaption in dry cows is indicative for a higher heat tolerance and the prioritization of the nutritional requirements of the fast-growing near-term fetus. These findings indicate that the development of future nutritional strategies for attenuating impairments of health and performance due to ambient heat requires the consideration of the physiological stage of dairy cows.

The onset of milk production lets mammals experience an enormous energy and nutrient demand. To meet these requirements, high-yielding dairy cows mobilize body fat resulting in an augmented hepatic oxidative metabolism, which has been suggested to signal for depressing hunger after calving. To examine how the extent of fat mobilization influences hepatic oxidative metabolism and thus potentially feed intake, blood and liver samples of 19 Holstein cows were taken throughout the periparturient period. Retrospectively grouped according to high (H) and low (L) liver fat content, H cows showed higher fatty acid but lower amino acid plasma concentrations and lower feed intake than L cows. The hepatic phospho-AMPK/total AMP ratio was not different between groups but decreased after parturition. A 2-DE coupled MALDI-TOF-TOF analysis and qRT-PCR studies revealed H cows having lower expressions of major enzymes involved in mitochondrial β-oxidation, urea cycling, and the pentose phosphate pathway but higher expressions of enzymes participating in peroxisomal and endoplasmic fatty acid degradation, pyruvate and TCA cycling, amino acid catabolism, oxidative phosphorylation, and oxidative stress defense. These data indicate that increasing lipolysis leads to augmenting nutrient catabolism for anaplerosis and mitochondrial respiration, providing a molecular link between hepatic oxidative processes and feed intake.