Sialidase activity in rimantadine-resistant and -sensitive influenza A viruses.

Rimantadine-resistant and -sensitive influenza A variants were assayed for their sialidase (neuraminidase, EC 3.2.1.

Proteins of Newcastle disease virus envelope: interaction between the outer hemagglutinin-neuraminidase glycoprotein and the inner non-glycosylated matrix protein.

Using linear sucrose-density ultracentrifugation analysis of Triton-solubilized Newcastle Disease Virus envelopes, we have evidenced, for the first time, the existence of interactions between the outer hemagglutinin-neuraminidase transmembrane glycoprotein and the inner non-glycosylated peripheral matrix protein. Such interactions seem to be electrostatic. These conclusions are based on the behavior of both proteins at different ionic strengths.

Comparison of biological and physical properties of human and animal A(H1N1) influenza viruses.

The study of biological properties of influenza virus strains belonging to the same subtype A(H1N1) and closely antigenically related, but isolated from different animal species (man, pig and duck), demonstrated that avian strains were more resistant than those isolated from mammals to high temperature and low pH, as shown by titration of residual infectivity in cell cultures (MDCK) and by sialidase assay. The difference in behaviour could be correlated to biological adaptation of the virus to its host. Avian body temperature is 40 degrees C and influenza virus, in ducks, is enterotropic and therefore capable of passing through the low pH values in the upper digestive tract of the animal.

Comparative studies of two acid beta-galactosidases from rabbit and bovine kidney.

Comparative studies of two acid beta-galactosidases from rabbit and bovine kidney have been made. The enzyme from rabbit (enzyme I) was purified 450-fold, and the activity of the bovine enzyme (enzyme II) was enriched 250-fold using conventional purification methods. Both purified enzymes were characterized and their properties were compared.

Kinetic studies on the sialidase of three influenza B and three influenza A virus strains.

Sialidase of influenza virus type A has been extensively studied through structural and kinetic approaches. However, sialidase of influenza virus type B has been less investigated. In this work, we have studied the activity and some properties (optimal pH, KM, Vmax, thermal stability) of sialidase in three influenza virus strains of type B (circulating in the period 1983-86) and also the activity and properties of sialidase from three virus strains of type A circulating at the same period of time.

Purification and characterization of a broad specificity beta-glucosidase from sheep liver.

1. A soluble beta-glucosidase from sheep liver has been isolated and purified 114-fold by conventional enzyme fractionation procedures. The specific activity of the purified enzyme was 5910 mU/mg of protein.

O-acetylated sialic acids in gangliosides from pig spleen lymphocytes.

The sialic acid content of gangliosides from pig spleen lymphocytes was studied by thin-layer chromatography. N-glycolylneuraminic acid and N-acetylneuraminic acid were detected for the first time in this material as the major sialic acids. In addition, two other sialic acids, tentatively designated O-acetylated sialic acids, according to their RF values on cellulose plates, were also found.

Changes in forebrain, cerebellum and brain stem phospholipid patterns from mothers and newborn rats after chronic pentazocine treatment during the gestation period.

Pregnant female Wistar rats were injected with pentazocine intramuscularly during the first nineteen days of the gestation period. The initial dose (1.8 mg/kg body weight) was increased daily by 1.

Purification and characterization of acid beta-D-galactosidase from rabbit spleen.

beta-D-Galactosidase has been purified to apparent homogeneity from rabbit spleen. The purification steps involved ammonium sulphate precipitation, DEAE-cellulose, concanavalin A-Sepharose, Sephadex G-200, and Sepharose 4B-(epsilon-aminocaproyl)-2-deoxy-beta-D-glucosylamine affinity chromatographies. In the DEAE-cellulose step, the beta-D-galactosidase was separated into two molecular forms, designated I and II, with similar pH optimum, Km, substrate specificity, and sensitivity to substrate analogues and other substances.

Externalization of aminophospholipids in platelet liposome bilayers by supplementation with sphingomyelin.

Negatively charged phospholipids are mainly located on the inner leaflet of platelet liposomes. Using a specific reagent for amino groups, trinitrobenzenesulfanilic acid, we have shown that in large artificial vesicles prepared with total lipids from sheep platelets supplemented with increased amounts of exogenous sphingomyelin, an alteration in the amino-phospholipid topology occurs, with a progressive appearance of these lipid species -in particular phosphatidylserine- in the outer membrane bilayer.

Effect of intestinal ischemia on pulmonary surfactant. An experimental study.

The infective factor seems to be very important in the physiopathology of intestinal ischaemia syndrome, as we suggested in previous research works, and is probably responsible for the disturbances observed in pulmonary surfactant. In the present research project, 48 mongrel dogs were studied under different situations of experimental intestinal ischaemia (arterial, venous and revascularization) after laparotomy and the pulmonary surfactant was determined in all cases. We conclude that the observed changes in phospholipids (phosphatidylglycerol and phosphatidylinositol particularly) can be directly related to the infective factor and important enough to induce physicochemical alterations of the surfactant and subsequently pulmonary function.

N-acetyl-beta-D-hexosaminidase A from rat urine: partial purification and characterization.

N-Acetyl-beta-D-hexosaminidase A was purified from rat urine by ion-exchange chromatography on DEAE-cellulose, followed by concanavalin A chromatography, and finally by chromatography on 2-acetamido-N-(epsilon-aminocaproyl)-2-deoxy-beta-glucosylamine-Se pharose 4B. The enzyme was purified 482-fold with a yield of about 7%. The optimal pH was 4.

Rearrangement of aminophospholipids in bilayers from sheep platelet plasma membranes and platelet liposomes by increasing their cholesterol levels.

Phospholipid orientation in platelet plasma membranes and other blood cells, such as erythrocytes, appears to be rather similar. The negatively charged phospholipids are almost exclusively located on the inner leaflet of the bilayer. No phosphatidylserine is present on the outer membrane bilayer.

Separation and characterization of four forms of beta-N-acetylhexosaminidase from chicken brain.

Chicken brain beta-N-acetylhexosaminidases from embryos (16 and 21 days old), newborns (1 and 4 days old), and adults (3 1/2 months and 2 years old) were separated into four different forms by ion exchange chromatography on diethylaminoethyl-cellulose. Three of these forms were "acid" hexosaminidases (I, IIA, and IIB), and the fourth was a "neutral" form. Throughout development of the chicken, forms IIA and III maintained the same activity ratio, whereas that for form I decreased and that for form IIB showed an increase.

Ganglioside alterations in various brain areas, liver and kidney from chronic alcoholic rats.

Ethanol was administered to Wistar male rats for 4 or 10 months and to female rats for 21 2 months (including gestation), using a 20% ethanol-water solution as the only fluid. Gangliosides (expressed as NeuAc) from forebrain, cerebellum, brain stem, liver and kidney of the alcoholic rats and their newborns were determined by densitometry. Forebrain and liver from males showed a statistically significant increase in their ganglioside-NeuAc content after 4 months of alcohol ingestion.

Isolation, characterization and phospholipid composition of lamellar bodies and subcellular fractions from dog lung.

1. Lamellar body fractions from dog lung can be separated by a procedure based on differential centrifugation before ultracentrifugation onto a discontinuous sucrose gradient. This fraction yields about 1% of total protein from the homogenate.

Kinetic studies of four enzyme forms of beta-N-acetylhexosaminidase from embryonic chicken brain.

The separation of four different hexosaminidase forms from embryonic chicken brain (16-day-old) has been performed by ion-exchange chromatography. Two different DEAE-cellulose columns have been used: a first one at pH 7.2 and a second one at pH 6.

Ganglioside composition of liver and kidney from rat after pentazocine treatment.

1. Female non-pregnant rats were intramuscularly injected with pentazocine for 3 months. Liver showed a statistically significant (P less than 0.

Heterogeneity of acid beta-galactosidase from rabbit kidney.

1. Rabbit kidney acid beta-galactosidase can be resolved into three peaks (named A3, A2 and A1) by gel-filtration chromatography. Their estimated molecular weights were: more than 250,000, 150,000 and 17,000 respectively.

Properties and kinetics of a neutral beta-galactosidase from rabbit kidney.

A neutral beta-galactosidase has been purified by concanavalin A-Sepharose affinity chromatography, DEAE-cellulose chromatography, Sephadex G-200 gel filtration and hydroxylapatite chromatography. The enzyme was purified 126-fold with a yield of about 21%. This form has a neutral optimal pH (7.