Oligothiophene isothiocyanates as a new class of fluorescent markers for biopolymers

The regioselective synthesis of fluorescent oligothiophene isothiocyanates is described. The isothiocyanates were reacted with bovine serum albumin (BSA) following standard procedures and the optical properties of the oligothiophene-BSA conjugates were analyzed as a function of oligomer concentration, time, and irradiation power. The oligothiophene-BSA conjugates were chemically very stable and their photoluminescence characteristics persisted unaltered for several months. Photoluminescence data relative to the conjugate of an oligothiophene-S,S-dioxide isothiocyanate with monoclonal anti-CD8 antibody are reported. No fluorescence quenching was observed following the binding of the isothiocyanate to the antibody and the conjugate displayed high chemical stability and photostability.

Different recognition by clostripain of myelin basic protein in the lipid-free and lipid-bound forms

Different proteolytic enzymes were tested for their ability to degrade the myelin basic protein of the central nervous system, purified in two different forms, the lipid-free form and the lipid-bound form. As shown by SDS gel electrophoresis only clostripain, a thiol protease, was able to distinguish between the two MBPs since it degraded MBP only in the lipid-free form. The failure to degrade lipid-bound MBP by clostripain could not be ascribed to the presence of lipids, since the other proteolytic enzymes tested degraded both MBPs independently from lipids giving fragments with different size. These results may be related to different conformations of MBPs possibly relevant for the study of myelin structure and antigenic properties of the protein.

[Mental and physical stress of auxiliary nurses: analysis of management]

Seeking a better understanding of job stress, auxiliary nurses were evaluated in General Hospitais Belo Horizonte. The emotional stress which accompanies auxiliary nurses caring for the sick and easing physical and mental suffering effects their own mental state and physical health. Elements that cause suffering and diseases can be attenuated or intensified depending on labor relations. However, organizations have not been concerned about working conditions. This paper suggests some protective safety and health measures that can improve labor relations and consequently reduce the suffering of working in hospitals.

Identification of water-soluble proteases in myelin preparations

Sodium chloride extracts obtained from purified bovine brain myelin were found to contain proteolytic activity capable of degrading isolated myelin basic protein as assessed by SDS gel electrophoresis. Using gels copolymerized with gelatin as substrate, two bands at about 54 and 117-125 KDa, respectively, were detected. Activity corresponding to the 54 KDa band was inhibited by zinc. Data presented in this article suggest that proteolytic activity can be released from the myelin sheath in water-soluble form and recognize MBP as substrate.

Purification of lipid-associated basic protein from guinea pig spinal-cord myelin

Myelin basic protein (MBP) was purified from guinea pig spinal-cord in a native-like form retaining the binding to all the myelin lipids. Since the guinea pig MBP was found to be much more labile than the corresponding MBP from bovine brain, the original procedure based on the use of hydroxyapatite and detergents was slightly modified as reported here. The product of this purification, lipid-bound MBP, may represent an alternative to lipid-free MBP for the induction, the study and the treatment of experimental allergic encephalomyelitis.

Zinc as an inhibitor of myelin basic protein proteolytic breakdown in the central nervous system

It is known that central nervous system myelin contains proteolytic enzymes which degrade the myelin basic protein (MBP). We have found that zinc acetate is able to inhibit MBP cleavage at concentrations of 1 mM or higher. Furthermore, the Zn-inhibitable MBP-degrading activity was found to be water-soluble and able to recognize MBP also if this protein was protected by its lipidic environment in the native-like, lipid-bound form. Data presented here suggest a Zn-dependent metallo-protease which recognize MBP as a substrate probably even in the myelin sheath, when the protein is not yet released from the membrane.

Synthesis and secretion of colonic glycoproteins: evidence for shedding in vivo of low molecular weight membrane components

In vivo glycoprotein synthesis and secretion was studied in rat colonic epithelial cells using precursor labelling with radiolabelled glucosamine. Sepharose 4B gel filtration of radiolabelled glycoproteins obtained from isolated colonic epithelial cells revealed two major fractions: (1) high molecular weight mucus in the excluded fraction and (2) lower molecular weight glycoproteins in the included volume. These glycoproteins were further fractionated by affinity chromatography on concanavalin A-Sepharose. The low molecular weight [3H]glucosamine-labelled glycoproteins contained a major subfraction which specifically adhered to concanavalin A, and could be eluted with 0.2 M alpha-methylmannoside. Fractionation of the concanavalin A-reactive glycoproteins on Sephadex G-100 revealed a major peak with a molecular weight of 15 000. In contrast, high molecular weight mucus glycoprotein did not adhere appreciably to concanavalin A-Sepharose. Perfusion experiments indicated that colonic secretions contained both mucus and concanavalin A-reactive glycoproteins. The major concanavalin A-reactive glycoprotein in the colonic perfusate was not derived from serum, but was released directly from the colonic membrane into the lumen.

Galactosyltransferase in fetal, neonatal, and adult colon: relationship to differentiation

Microsomal galactosyltransferase activity of fetal rat colon increased fourfold between 18 and 22 days of gestation and then more slowly during neonatal life reaching adult levels after 14 days. The Km for uridinediphosphate- (UDP) galactose, pH optimum, cation, and detergent requirements were identical in fetal and adult galactosyltransferase. Cytidine 5'-diphosphate-choline stimulated the adult but not fetal colonic galactosyltrasferase activity by inhibition of UDP-galactose pyrophosphatase. The increase in colonic galactosyltransferase in late fetal development is correlated with our previous observation that incorporation of [3H]galactose is markedly increased during differentiation of the fetal colon.

Stimulation of colonic glycoprotein synthesis by dibutyryl cyclic AMP and theophylline

The effects of dibutyryl cyclic AMP (B2cAMP) and theophylline on glyoprotein synthesis in rabbit colon were studied in mucosal organ cultures using [3H]glucosamine as a precursor. Addition of B2cAMP (1 mm) to culture medium caused a significant increase in glycoprotein synthesis after 12 and 24 hr compared with biopsies cultured in control medium. The increase in glycoprotein synthesis was observed only if the cyclic nucleotide was present continuously in the incubation medium for at least 12 hr. The stimulatory effect of B2cAMP on [3H]glucosamine incorporation was blocked by cycloheximide. B2cAMP also stimulated mucosal uptake of glucosamine into the intracellular pool and markedly enhanced specific activity of mucosa galactosyltransferase, an enzyme involved in glycoprotein synthesis. Addition of 5mM theophylline caused a greater than 2-fold increase in cAMP levels, which was also accompanied by an increase in glucosamine uptake and incorporation into mucosal glycoproteins. This study demonstrates that elevation of intracellular cAMP concentration in colon epithelium in vitro is associated with an increase in glycoprotein synthesis. These effects may be mediated in part by (1) increased uptake of glycoprotein precursors such as glucosamine, and (2) increased activity of glycoprotein synthetic enzymes.