Processing of snake venom l-amino acid oxidase during intracellular transport

The isoelectrofocusing patterns of l-amino acid oxidase (LAO) from venom gland homogenates and of the secreted venom of Vipera palaestinae have been compared. The LAO isozyme profile of actively synthesizing gland spans over a wider range of pIs (4.8–6.0) and includes more variants as compared with the profile of the secreted venom. A basic shift of the isoelectrofocusing pattern of LAO obtained by treatment of the gland homogenate or the venom with neuraminidase indicates that sialic acid residues are responsible for the changes in the electronegativity of the isozymes. Analyses of subcellular fractions show that the microsomal fraction of the venom gland homogenate exhibits the highest multiplicity of molecular forms of LAO, whereas the fraction including the secretory granules has an isozyme profile similar to the venom. Double labelling experiments show that the newly synthesized LAO include isozymes which span over a wide range of pIs, whereas later on labelling of the more acidic isozymes is prominent. The results obtained may suggest that the sialic acid residues which are attached to LAO during its transport serve as “markers” for secretion.     

Sequential degradation of a chondroitin sulphate trisaccharide by lysosomal enzymes from embryonic-chick epiphysial cartilage.

The disulphated trisaccharide D-N-acetylgalactosamine sulphate-beta-D-glucuronic acid-beta-D-N-acetylgalactosamine sulphate prepared from 35S- or 14C-labelled chondroitin sulphate was incubated with a preparation of lysosomal enzymes from embryonic-chick epiphysial cartilage. Degradation was demonstrated by analysis of the reaction products. By use of the appropriate intermediate products as substrates, in conjunction with specific enzyme inhibitors, it was shown that the degradation proceeded sequentially from the non-reducing end. It was initiated by sulphatase (preferentially hydrolysing sulphate ester groups at the 6-position), followed by beta-N-acetylgalactosaminidase and beta-glucuronidase, converting the substrate into monosaccharides and inorganic sulphate. The latter enzyme preferentially attacked disaccharides carrying their sulphate ester group at C-4 of the hexosamine residue. Generation of chondroitin sulphate oligosaccharides may occur by the action of an endoglycosidase, previously demonstrated in embryonic-chick cartilage. Endo- and exo-enzymes may thus form a functional unit in lysosomal degradation of chondroitin sulphate.     

Immobilization of enzymes based on hydrophobic interaction. III. Adsorbent substituent density and its impact on the immobilization of β-amylase

Hexyl-groups have been introduced into crosslinked Sepharose 6B, yielding gels with degrees of substitution which range from 0.02 to 0.70 mol hexyl-side chain per mole galactose residue. The gels were exposed to β-amylase in solution, and the resulting adsorbates indicated a monotonic increase in adsorption capacity with an increasing hexyl-content. Adsorbate activity, by contrast, displayed a maximum for a carrier gel with a hexyl–galactose ratio of 0.51. Adsorbates based on gels with different hexyl-content were used in column reactors for continuous maltose production from a soluble starch substrate.     

Mechanobiology of conjunctival epithelial cells exposed to wall shear stresses

Biomechanics and Modeling in Mechanobiology - The human conjunctival epithelial cells (HCEC) line the inner sides of the eyelids and the anterior part of the sclera. They include goblet cells that...     

Circulating plasma microRNAs in colorectal neoplasia: A pilot study in assessing response to therapy

IntroductionCurrent serological surveillance markers to monitor colorectal cancer (CRC) or colorectal advanced adenomas (CAA) are hampered by poor sensitivity and specificity. The aim of this study is to identify and validate a panel of plasma microRNAs which change in expression after resection of such lesions.MethodsA prospectively maintained colorectal surgery database was queried for patients in whom both pre- and post-procedural serum samples had been obtained. An initial screening analysis of CRC and CAA patients (5 each) was conducted using screening cards for 380 miRNAs. Four identified miRNAs were combined with a previously described panel of 7 miRNAs that were diagnostically predictive of CRC and CAA. Differential miRNA expression was assessed using quantitative real-time polymerase chain reaction(qRT-PCR).ResultsFifty patients were included (n = 27 CRC, n = 23 CAA). There was no difference in age, gender, or race profile of CRC patients compared to CAA patients. Six miRNA were significantly increased after CRC resection (miR-324, let7b, miR-454, miR-374a, miR-122, miR-19b, all p<0.05), while three miRNAs were significantly increased following CAA resection (miR-454, miR-374a, miR-122, all p<0.05). Three miRNA were increased in common for both (miR-454, miR-374a, miR-122).DiscussionThe expression of miRNAs associated with neoplasia (either CRC or CAA) was significantly increased following surgical resection or endoscopic removal of CRC or CAA. Future studies should focus on the evaluation of these miRNAs in CRC and CAA prognosis.