Gender-specific effects of a phytogenic feed additive on performance, intestinal physiology and morphology in broiler chickens.

To date, most studies published were carried out on broilers of the same sex, and possible gender-specific effects of phytogenic substances have not been investigated so far. A 3 × 2 factorial study was performed to examine gender-specific effects of a PFA at two dietary levels (150, 1500 ppm) on growth performance, carcass traits and gastrointestinal attributes in broiler chickens versus an untreated control group. The addition of 150 ppm of the PFA led to a downregulation of trypsinogen mRNA in pancreas compared with the control group (p < 0.05). The number of goblet cells decreased in jejunum compared with the unsupplemented group, whereby this effect was more pronounced in male birds (p < 0.05). Furthermore, higher methylamine contents compared with the control group were measured (p < 0.01). In proximal ileum, female birds, supplemented with 150 ppm PFA, had lower crypt depths than their litters in the 1500 ppm treatment (p < 0.05). In distal ileum, villus height:crypt depth ratio was higher in birds fed the PFA at 150 ppm than in the control group (p < 0.05). The 1500 ppm dosage of the PFA increased jejunal histamine concentration compared with the negative control group (p < 0.05). Jejunal histamine concentration was also affected by the interaction PFA × sex (p < 0.05). Regardless of inclusion level, total amount of biogenic amines and other microbial metabolites in digesta samples was not affected by the PFA. These results demonstrate variable, partially gender-specific effects of the tested PFA. Although the supplementation of 150 ppm showed little effect on mRNA expression level of selected marker genes for nutrient digestion, beneficial effects on gut morphology were observed. The 10-fold higher dosage of the PFA did not adversely affect growth performance as well as most investigated parameters compared with the control group.

Preparation of fluorescently-labeled amyloid-beta peptide assemblies: the effect of fluorophore conjugation on structure and function.

Recent research has focused on soluble oligomeric assemblies of the 42 amino acid isoform of the amyloid-beta peptide (A beta 42) as the proximal cause of neuronal injury, synaptic loss, and the eventual dementia associated with Alzheimer's disease (AD). While neurotoxicity, neuroinflammation, and deficits in behavior and memory have all been attributed to oligomeric A beta 42, the specific roles for this assembly in the cellular neuropathology of AD remain poorly understood. In particular, lack of reliable and well-characterized forms of easily detectable A beta 42 oligomers has hindered study of the cellular trafficking of exogenous A beta 42 by neurons in vitro and in vivo. Therefore, the objective of this study is to fluorescently label soluble oligomeric A beta 42 without altering the structure or function of this assembly. Previous studies have demonstrated the advantages of using tapping mode atomic force microscopy (AFM) to characterize the structural assemblies formed by synthetic A beta 42 under specific solution conditions (e.g., oligomers, protofibrils, and fibrils). Here, we extend these methods to establish a strategy for fluorescent labeling of oligomeric A beta 42 assemblies that are structurally comparable to unlabeled oligomeric A beta 42. To compare function, we demonstrate that the uptake of labeled and unlabeled oligomeric A beta 42 by neurons in vitro is similar. AFM-characterized fluorophore-A beta 42 oligomers are an exciting new reagent for use in a variety of studies designed to elucidate critical cellular and molecular mechanisms underlying the functions of this A beta 42 assembly form in AD.

Disruption of fast axonal transport is a pathogenic mechanism for intraneuronal amyloid beta.

The pathological mechanism by which Abeta causes neuronal dysfunction and death remains largely unknown. Deficiencies in fast axonal transport (FAT) were suggested to play a crucial role in neuronal dysfunction and loss for a diverse set of dying back neuropathologies including Alzheimer's disease (AD), but the molecular basis for pathological changes in FAT were undetermined. Recent findings indicate that soluble intracellular oligomeric Abeta (oAbeta) species may play a critical role in AD pathology. Real-time analysis of vesicle mobility in isolated axoplasms perfused with oAbeta showed bidirectional axonal transport inhibition as a consequence of endogenous casein kinase 2 (CK2) activation. Conversely, neither unaggregated amyloid beta nor fibrillar amyloid beta affected FAT. Inhibition of FAT by oAbeta was prevented by two specific pharmacological inhibitors of CK2, as well as by competition with a CK2 substrate peptide. Furthermore, perfusion of axoplasms with active CK2 mimics the inhibitory effects of oAbeta on FAT. Both oAbeta and CK2 treatment of axoplasm led to increased phosphorylation of kinesin-1 light chains and subsequent release of kinesin from its cargoes. Therefore pharmacological modulation of CK2 activity may represent a promising target for therapeutic intervention in AD.