Characterization of Jamaican agro-industrial wastes. Part II, fatty acid profiling using HPLC: precolumn derivatization with phenacyl bromide.

This paper describes the determination of fatty acid composition of coffee, citrus and rum distillery wastes using reversed-phase high-performance liquid chromatography (RP-HPLC). Lipid extracts of the waste samples are derivatized with phenacyl bromide and their phenacyl esters are separated on a C8 reversed-phase column by using continuous gradient elution with water and acetonitrile. The presence of saturated and unsaturated fatty acids in quantifiable amounts in the examined wastes, as well as the high percentage recoveries, are clear indications that these wastes have potential value as inexpensive sources of lipids. The HPLC procedures described here could be adopted for further analysis of materials of this nature.

Characterization of Jamaican agro-industrial wastes. Part I: characterization of amino acids using HPLC: pre-column derivatization with phenylisothiocyanate.

Jamaican agro-industries generate large quantities of wastes, which are either discarded or under-utilized. In order to evaluate the possible utilization of these wastes, it is necessary that the profiles of the major biochemical groups be developed. This paper describes the determination of the amino acid composition of coffee, citrus, and rum distillery wastes using a reversed-phase high-performance liquid chromatography method. Acid hydrolysates of the wastes are derivatized with phenylisothiocyanate. They are analyzed as their phenylthiocarbamyl derivatives and determined quantitatively using norleucine as the internal standard. The presence of all the 17 amino acids investigated, nine of which include those essential for animal nutrition, are observed in the samples investigated, suggesting a high quality of protein with implications in the formulation of animal feeds.

The mitogen-activated/extracellular signal-regulated kinase kinase 1/2 inhibitor U0126 induces glial fibrillary acidic protein expression and reduces the proliferation and migration of C6 glioma cells.

The extracellular signal-regulated kinase (ERK) signaling pathway has been implicated in diverse cellular functions. ERK and its activating kinase, mitogen-activated/extracellular signal-regulated kinase kinase (MEK), are downstream of cell surface receptors known to be up-regulated in many malignant gliomas. We sought to investigate the role of ERK in glioma cell migration, proliferation and differentiation using the rat-derived C6 glioma cell line and the MEK inhibitor, U0126. Treatment of C6 cells with U0126 caused a significant concentration-dependent reduction in cell proliferation and migration and also induced expression of glial fibrillary acidic protein, a marker of astrocytic differentiation. These results suggest that the ERK pathway regulates glioma cell proliferation, migration and differentiation.

Valproic acid induces caspase 3-mediated apoptosis in microglial cells.

Valproic acid is widely used for the treatment of epilepsy and mood disorders, but its mode of action is unclear. Treatment of neuronal cells with valproic acid promotes neurite sprouting, is neuroprotective and drives neurogenesis; however its effects on non-neuronal brain cells are less clear. We report that valproic acid induces apoptosis in the mouse microglial cell line, BV-2, at concentrations within the therapeutic range. When BV-2 cells were incubated for 24 h with 500-1000 microM valproic acid we observed a reduction in cell number, the appearance of apoptotic morphology and increased caspase 3 cleavage. Exposure of a macrophage cell line (RAW 264.7) to similar concentrations of valproic acid also led to reduced cell number but no caspase 3 cleavage, suggesting these cells responded to valproic acid with reduced proliferation rather than apoptosis. This was confirmed using bromodeoxyuridine incorporation studies. Similar concentrations of valproic acid added to Neuro-2a, SK-N-SH and C6 cell lines as well as human NTera-2 astrocytes did not evoke cell death. The caspase 3 inhibitor DEVD-CHO inhibited valproic acid-induced apoptosis in BV-2 cells whereas the MEK inhibitor U0126 potentiated valproic acid-mediated apoptosis. These results demonstrate that valproic acid selectively induces apoptosis in BV-2 cells by way of a caspase 3-mediated action. As activated microglia secrete neurotoxins in neurodegenerative diseases such as Alzheimer's, Parkinson's, and HIV dementia, valproic acid may alleviate these diseases by selectively killing microglia.

Activated c-Jun is present in neurofibrillary tangles in Alzheimer's disease brains.

Alzheimer's disease (AD) pathology is characterized by the presence of insoluble beta-amyoid deposits and neurofibrillary tangles containing hyperphosphorylated tau. Increased expression of the immediate early gene product c-Jun has also been reported in post-mortem AD brains, and the presence of upstream regulators of c-Jun has been described in tangle formations. Here, we report the presence of c-Jun specifically phosphorylated on ser-63, but not ser-73, in tangle-bearing neurons and in 'late-stage' extracellular tangles in AD brains. Western blot analysis confirmed the presence of c-Jun phosphorylated on ser-63 but not on ser-73 in AD brain tissue. The expression of differentially phosphorylated c-Jun in the AD brain may reflect the contradictory roles of these phosphorylation sites in neurons. Furthermore, the inappropriate sequestration of phosphorylated c-Jun in tangles in AD brains may contribute to AD pathology and neurodegeneration.

Activating transcription factor 2 expression in the adult human brain: association with both neurodegeneration and neurogenesis.

Activating transcription factor 2 (ATF2) is a member of the activator protein-1 family of transcription factors, which includes c-Jun and c-Fos. ATF2 is highly expressed in the mammalian brain although little is known about its function in nerve cells. Knockout mouse studies show that this transcription factor plays a role in neuronal migration during development but over-expression of ATF2 in neuronal-like cell culture promotes nerve cell death. Using immunohistochemical techniques we demonstrate ATF2 expression in the normal human brain is neuronal, is found throughout the cerebral cortex and is particularly high in the granule cells of the hippocampus, in the brain stem, in the pigmented cells of the substantia nigra and locus coeruleus, and in the granule and molecular cell layers of the cerebellum. In contrast to normal cases, ATF2 expression is down-regulated in the hippocampus, substantia nigra pars compacta and caudate nucleus of the neurological diseases Alzheimer's, Parkinson's and Huntington's, respectively. Paradoxically, an increase in ATF2 expression was found in the subependymal layer of Huntington's disease cases, compared with normal brains; a region reported to contain increased numbers of proliferating progenitor cells in Huntington's disease. We propose ATF2 plays a role in neuronal viability in the normal brain, which is compromised in susceptible regions of neurological diseases leading to its down-regulation. In contrast, the increased expression of ATF2 in the subependymal layer of Huntington's disease suggests a role for ATF2 in some aspect of neurogenesis in the diseased brain.