Anti-inflammatory procyanidins and triterpenes in 109 apple varieties

We evaluated the potential of apple to reduce inflammation. Phenolic compounds and triterpenes were analyzed in 109 apple cultivars. Total phenolics ranged from 29 to 7882 μg g(-1) of fresh weight (FW) in the flesh and from 733 to 4868 μg g(-1) FW in the skin, with flavanols including epicatechin and procyanidins as major components. Ursolic (44.7 to 3522 μg g(-1) FW) and oleanolic (47.2 to 838 μg g(-1) FW) acids dominated the skin triterpene profile. Five chemically contrasting cultivars were fractionated and their immune-modulating activity measured using two cell-based assays targeting key points in the inflammation process. Cultivars exhibiting high contents of procyanidins were the most potent at inhibiting NF-κB while triterpene-rich fractions reduced the promoter activity of the gene of TNFα. This study provides new insights into how apple genetic diversity could be used to alleviate inflammation.

M3 muscarinic receptors promote cell survival through activation of the extracellular regulated kinase (ERK1/2) pathway

Activation of certain subtypes of the muscarinic acetylcholine receptor can enhance cell survival. In SK-N-SH human neuroblastoma cells, muscarinic acetylcholine receptor activation induces phosphorylation of CREB and induction of EGR1, transcription factors associated with cell growth and survival. We identified the M3 muscarinic acetylcholine receptor subtype as being primarily responsible for these transcription factor responses after stimulation with carbachol, using subtype-preferring receptor antagonists and muscarinic snake toxins. In a cell survival/death model in SK-N-SH cells deprived of serum growth factors, carbachol increased cell viability, an effect blocked by the non-specific muscarinic antagonist atropine and the M3-preferring antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), suggesting that the M3 receptor is also driving the survival response in these cells. This cytoprotection is largely dependent on activation of the p44/42 extracellular regulated kinase (ERK1/2) pathway. Understanding such survival signalling pathways is important for both potential interventions in neurodegenerative disease and for targeting neuroblastoma and malignancies of the central nervous system.

Cellular composition of human glial cultures from adult biopsy brain tissue

Microglia and astrocytes play vital roles in normal human brain function and in neurological disorders. To study their physiological and pathological roles it is desirable to establish in vitro systems that are derived from the adult human brain. Although several groups have successfully cultured cells from the human brain, the composition of these cultures remains controversial. Using morphological criteria, immunocytochemical analysis and a BrdU incorporation assay we demonstrate the presence of poorly proliferative microglia and astrocytes in cultures derived from epilepsy biopsy tissue. In addition, we characterized a third cell type as fibronectin and prolyl 4-hydroxylase immunopositive fibroblast-like cells, which are highly proliferative and become the predominant cell type after successive sub-culturing. Therefore, although cultures from adult human brain tissue provide an excellent resource for studying human glial cells, careful consideration must be given to their cellular composition when performing studies using these methods.

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.

ATF3 enhances c-Jun-mediated neurite sprouting

The AP-1 transcription factor c-Jun is induced in axotomized neurons of the peripheral and central nervous systems, and in both cases upregulation of c-Jun expression has been correlated with axonal regeneration. More recently there has been interest in the c-Jun-related bZIP transcription factor, ATF3, and its function in neurons. ATF3 is also induced in nerve cells in response to axotomy and there is a correlation between increased ATF3 expression and upregulation of c-Jun in surviving neurons. Moreover, c-Jun is able to induce expression of ATF3. We investigated the effect of co-expressing c-Jun and ATF3 in two neuronal-like cell lines to model transcriptional events occurring in axotomized neurons undergoing regeneration. We show that expression of ATF3 with c-Jun significantly enhances c-Jun-mediated neurite sprouting, and that this phenotype is most likely mediated by a physical association of these two transcription factors. Our results suggest that a program of axonal regeneration is initiated when both c-Jun and ATF3 are upregulated in neurons in response to axotomy.

Induction and experience-dependent consolidation of stable long-term potentiation lasting months in the hippocampus

Long-term potentiation (LTP) is widely regarded as a memory mechanism, but it is not known whether it can last long enough to underlie very long-term memory. We report that high-frequency stimulation (HFS) paradigms applied to the rat dentate gyrus can elicit stable LTP lasting months and up to at least 1 year. The induction of stable LTP was sensitive to stimulation variables on the day of HFS and was associated with phosphorylation of cAMP response element-binding protein. The maintenance of stable LTP was also experience-dependent, because it was reversed when animals were exposed repeatedly to an enriched environment beginning 14 d post-HFS. However, stable LTP eventually consolidated over time and became resistant to reversal, because exposure to enriched environments 90 d post-HFS failed to influence stable LTP maintenance. Thus, LTP can be shown to meet one of the principal criteria for a very long-term memory storage mechanism. However, under naturalistic environmental conditions, LTP may normally be retained in the hippocampus for only short periods of time.

Muscarinic receptor-mediated phosphorylation of cyclic AMP response element binding protein in human neuroblastoma cells

This study describes the effect of signalling through muscarinic acetylcholine receptors on two transcription factors implicated in long-term synaptic plasticity and memory formation, EGR1 and the cyclic AMP response element binding protein (CREB). In SK-N-SH neuroblastoma cells, treatment with the cholinergic agonist carbachol led to maximal induction of EGR1 1 h after stimulation. This was preceded by the phosphorylation of CREB, which peaked as early as 5 minutes after carbachol treatment. The levels of both EGR1 and phosphorylated CREB (pCREB) slowly decayed over 4-8 h. CREB phosphorylation and EGR1 induction showed similar sensitivity to carbachol concentration, with EC(50) values in the range of 1-10 microM, and the changes in both transcription factors were blocked by the muscarinic antagonist atropine. As has been described elsewhere, EGR1 induction was dependent on activation of p42/44 MAP kinase, as it was blocked by the MEK inhibitor U0126. However, CREB phosphorylation by carbachol was largely unaffected by MAP kinase blockade. As both CREB phosphorylation and EGR1 induction have been linked to long-term potentiation and some forms of memory consolidation, these results may implicate CREB and EGR1 in independent or partially independent cholinergic signalling pathways involved in memory processes.

The pTugA and pTugAS vectors for high-level expression of cloned genes in Escherichia coli

Plasmids pTugA and pTugAS, designed for expression of cloned genes in Escherichia coli, possess the features of high-level inducible transcription, enhanced RNA translation, portability, high copy number, stability and versatility. In addition, pTugAS can be used to produce fusion proteins comprising a target protein and a cellulose-binding domain. Such fusion proteins can be purified in a single step by affinity chromatography on cellulose. Expression of two model gene fusions using the pTug plasmids resulted in yields of 500 mg of intracellular and 250 mg of extracellular recombinant protein per liter.

Purification of human interleukin-2 using the cellulose-binding domain of a prokaryotic cellulase

Engineering gene fusions which introduce an affinity tag linked to the target polypeptide by a specific protease cleavage site is widely used to facilitate recombinant protein purification. A fusion protein CBDAPT-IL-2, comprised of the cellulose-binding domain (CBD) and Pro-Thr (PT) rich linker of the Cellulomonas fimi endo-beta-1,4-glucanase A (CenA) and a factor Xa cleavage sequence (IleGluGlyArg) fused to the N terminus of human interleukin-2, was produced in Escherichia coli, Streptomyces lividans and mammalian COS cells. CBDAPT-IL-2, secreted from S. lividans or COS cells or recovered from the insoluble fraction of E. coli, could be purified by adsorption on cellulose. The intact fusion protein adsorbed to cellulose was hydrolyzed in situ with factor Xa to release active interleukin-2.

Use of monoclonal antibodies specific for the a determinant of K88 pili for detection of enterotoxigenic Escherichia coli in pigs

Monoclonal antibodies directed against the a determinant of K88 pili from porcine enterotoxigenic Escherichia coli which react with all three K88 variants have been produced. These antibodies have been used for diagnosis of porcine enterotoxigenic E. coli in a direct enzyme-linked immunosorbent assay with sensitivity to 50 ng of pilus protein per ml.

Cellulose-binding domains: potential for purification of complex proteins

The endoglucanase CenA and the exoglucanase Cex from Cellulomonas fimi each contain a discrete cellulose-binding domain (CBD), at the amino-terminus or carboxyl-terminus respectively. The gene fragment encoding the CBD can be fused to the gene of a protein of interest. Using this approach hybrid proteins can be engineered which bind reversibly to cellulose and exhibit the biological activity of the protein partner. Alkaline phosphatase (PhoA) from Escherichia coli, and a beta-glucosidase (Abg) from an Agrobacterium sp. are dimeric proteins. The fusion polypeptides CenA-PhoA and Abg-CBC(Cex) are sensitive to proteolysis at the junctions between the fusion partners. Proteolysis results in a mixture of homo- and heterodimers; these bind to cellulose if one or both of the monomers carry a CBD, e.g. CenA-PhoA/CenA-PhoA and CenA-PhoA/PhoA. CBD fusion polypeptides could be used in this way to purify polypeptides which associate with the fusion partner.

Effects of atrial natriuretic factor in conscious rhesus monkeys with acute volume expansion

The renal and hemodynamic responses to intravenous anaritide, a human atrial natriuretic factor [102-126] at 0.3 to 20 micrograms/kg in conscious rhesus monkeys with and without acute extracellular hypervolemia were analyzed and compared. Acute isotonic saline loading (intravenous bolus at 10 mL/kg plus continuous infusion at 0.25 mL/kg/min 30 min prior to and maintained throughout experiment) significantly augmented urine output (UV) and urinary Na+ excretion rate (UNaV) by 31% and 91%, respectively. Radial mean arterial pressure (MAP) and heart rate (HR) were not affected by volume expansion. Anaritide at doses higher than 0.3 micrograms/kg reduced MAP in a dose-dependent fashion in euvolemic monkeys. In contrast, reduction in MAP was observed only at the highest dose (20 micrograms/kg) of anaritide in hypervolemic monkeys. The hypotensive responses to anaritide at 20 micrograms/kg in euvolemic and hypervolemic animals were similar (-26 +/- 5 v -24 +/- 5 mm Hg, respective maximum changes in MAP). UV and UNaV were increased by anaritide at 3 to 20 micrograms/kg in both euvolemic and hypervolemic monkeys; however, the increases at each effective dose of anaritide were greater or tended to be greater in hypervolemic rhesus monkeys compared with euvolemic rhesus monkeys. Compared to vehicle responses, HR was not affected by anaritide in either group of animals. In conclusion, acute extracellular hypervolemia potentiates the renal but suppresses the hypotensive responses to anaritide in conscious rhesus monkeys.

Fusion to an endoglucanase allows alkaline phosphatase to bind to cellulose

Endoglucanase CenA of Cellulomonas fimi comprises an N-terminal cellulose-binding domain and a C-terminal catalytic domain joined together by a sequence of 23 proline and threonine residues (the Pro-Thr box). The domains function independently when separated by proteolysis. TnphoA has been used to generate cenA'-'phoA fusions. CenA'-'PhoA fusion polypeptides which contain the entire cellulose-binding domain of CenA bind to cellulose, allowing their purification from periplasmic extracts in a single, facile step. This result has implications for purification or immobilisation of chimeric proteins on a cheap cellulose matrix.

Predominance of the ac variant in K88-positive Escherichia coli isolates from swine

Monoclonal antibodies to K88ac and K88ab were used in enzyme-linked immunosorbent assays on Escherichia coli cultures known to produce K88 pili. A total of 415 K88-positive E. coli isolates from nine states were all found to be the K88ac variant. The cultures tested were isolated during the years 1976 to 1985.