PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “NEURAMINIDASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed1987

Surface glycoconjugates on rat photoreceptor cilium. Effect of neuraminidase digestion.

In retinal photoreceptors the connecting cilium constitutes a boundary between the inner and outer segments. In previous studies we demonstrated that, while opsin could be localized in abundance in the distal ciliary membrane, very little opsin was detected in the proximal ciliary plasma membrane. In the present study we extended our view of molecular specialization on the ciliary membrane with respect to glycoconjugates. Saccharide moieties of ciliary glycoconjugates were studied in immature and mature rat photoreceptors. Surface saccharides were detected and localized by means of ferritin-labeled lectins and electron microscopy. Dense labeling of the ciliary membrane surface with wheat germ agglutinin (WGA) was observed. In immature photoreceptors the labeling was restricted to the proximal ciliary membrane, in a region where opsin molecules could not be detected. Neuraminidase digestion abolished WGA binding to the proximal ciliary membrane surface, indicating that sialic acids mediate WGA binding to this domain. Peanut agglutinin (PNA) did not label the ciliary surface, nor did it bind to the surface of other photoreceptor domains. Neuraminidase digestion exposed numerous PNA binding sites on the ciliary membrane surface. In view of the carbohydrate specificity of PNA, we suggest that a terminal trisaccharide sequence, sialic acid-galactose-(beta 1----3)-N-acetyl galactosamine, is present in high density on the proximal ciliary membrane surface.

Animals↗
PubMedDate not supplied

[Measuring neuraminidase activity by the thiobarbiturate method].

A number of reducing agents used for removing the excess of periodate in the reaction of the neuraminidase (EC 3.2.1.18) activity measuring by the thiobarbituric acid technique were compared. The toxic reagent sodium arsenite may be replaced by a 20% solution of ascorbic acid. The modified technique of the neuraminidase activity determining can be used in case of both high-molecular weight substrate ovomucin and low-molecular weight substrate-glycomacropeptide from milk whey.

Indicators and Reagents↗
PubMed1985

Incubation with neuraminidase and affinity electrophoresis with wheat-germ lectin compared for separating and quantifying alkaline phosphatase isoenzymes in plasma.

Of 98 patients' specimens examined for alkaline phosphatase (EC 3.1.3.1) isoenzymes by electrophoresis on cellulose acetate membrane after incubation with neuraminidase, 50 showed only a single liver or bone isoenzyme staining band; in 15 of these, the tissue origin of the fraction could not be accurately identified from its electrophoretic location. In the remaining 48 specimens, both liver and bone fractions were identifiable, but in only 25 of these was the electrophoretic resolution sufficient to yield separate peaks on densitometry. In contrast, both liver and bone alkaline phosphatase isoenzymes were identified in 95 of the 98 specimens by affinity electrophoresis involving wheat-germ lectin, the detection of both fractions being in agreement with the results of sequential heat inactivation. The tissue origin of the enzyme bands was readily ascertainable from their consistent electrophoretic location in this medium, and in 89 of the specimens the isoenzyme fractions could be resolved into separate peaks on densitometry. We conclude that resolution of liver and bone alkaline phosphatase by incubation with neuraminidase followed by cellulose acetate electrophoresis is greatly inferior to that obtained by wheat-germ lectin affinity electrophoresis.

Alkaline Phosphatase↗
PubMed1986

Simple sugars with affinity for the macrophage asialoglycoprotein receptor are adjuvants for the humoral immune response to neuraminidase-treated sheep erythrocytes.

The influence of monosaccharides on the humoral immune response of mice to normal and neuraminidase-treated sheep red blood cells (SRBC) was investigated. In these studies, both the sugars and antigen were administered i.p. D-Galactose displayed adjuvant activity for neuraminidase-treated but not for normal SRBC. This activity was optimal at an antigen dose of 3 X 10(6) cells. Other monosaccharides with an axial hydroxyl group at position 4 and D-mannose-6-phosphate behaved like D-galactose, whereas structurally unrelated sugars did not. The adjuvant activity of the saccharides corresponded to the affinity of the substances for the asialo-glycoprotein receptor. The adjuvant effects were also expressed in cobra venom factor-treated and C5-deficient mice. This suggests that blockade of the asialo-receptor rather than complement is involved in this form of immunoadjuvant activity. The findings are also in support of our hypothesis that obstruction of nonimmune antigen elimination, in this case at the level of macrophages, would be one of the mechanisms underlying immunologic adjuvant activity.

Adjuvants, Immunologic↗
PubMed1979

Purified viral neuraminidase vaccine to control influenza.

The control of influenza by immunoprophylaxis is difficult because of the antigenic mutability of the influenza virus and the unpredictability of its epidemiologic behaviour. The inactivated whole-virus vaccine currently used is not ideal. Vaccination with pure neuraminidase is suggested. The induced antineuraminidase antibody will restrict viral invasion. Mild illness may or may not occur. On subsequent exposure to influenza virus the individual will produce antihemagglutinin and antineuraminidase antibodies and will be resistant to both infection and illness. Since antigenic changes are less frequent in the viral neuraminidase than in the viral hemagglutinin, the vaccine would be usable for longer periods than the presently used inactivated whole-virus vaccine.

Animals↗
PubMed1985

Neuraminidase increases DNA synthesis of spleen cells induced by native and asialylated erythropoietin.

The uptake of 3H-thymidine by a suspension of spleen cells, obtained from mice made anemic by phenylhydrazine injections, is increased above the values obtained with native human or mouse erythropoietin (Ep) if the hormone is enzymatically asialylated. Preparations of human Ep asialylated by mild acid hydrolysis stimulated DNA synthesis to a lesser extent than the native hormone; however, when neuraminidase was added to the culture medium, the stimulation exhibited by the asialylated Ep was not significantly different from the stimulation shown by the native hormone. The DNA synthesis of these cells is increased even more if neuraminidase and the asialylated hormone are added to the cell suspension. The asialylated Eps are not biologically active in vivo. The sialic acid moieties of Ep and of the cells responding to Ep are involved in the in vitro response of spleen cells to the hormone, possibly by making Ep receptors available to interact with the hormone.

Animals↗
PubMed1985

[Use of neuraminidase for improving the properties of the erythrocytic ganglioside diagnosticum].

In this work the possibility of using neuraminidase for increasing the content of ganglioside GM1 in the mixture of gangliosides used for the sensitization of erythrocytes has been studied. The study has revealed that the treatment of gangliosides with neuraminidase is sufficient for obtaining active hemosensitin; there is no need for the purification of the preparation by gel filtration.

Animals↗
PubMedDate not supplied

[Role of carbohydrates in the manifestation of the hemagglutinating and neuraminidase activities of the influenza virus].

Suspensions of influenza virions (MRC-11, X-7, and A/PR8/34 strains) were treated with a mixture of glycosidases including alpha-D-mannosidase, alpha-L-fucosidase, beta-D-galactosidase, and beta-D-N--acetylglucosaminidase for the study of the influence of carbohydrate part of influenza virus surface glycoproteins on the hemagglutinating and neuraminidase activity. The availability of oligosaccharide chains for the effect of glycosidases was found to change in relation to the functional status of the glycoprotein molecule. When carbohydrate residues were cleaved from neuraminidase in virus particle, its enzymatic activity did not change, whereas the hemagglutinating activity of virions after treatment with glycosidases decreased more than 50-fold.

Carbohydrates↗
PubMed1979

Effect of Clostridium perfringens neuraminidase on viability and antigenicity of human leukemic myeloblasts.

The effect of increasing concentrations of Cl. Perfringens neuraminidase and of pH on the dye exclusion ability and lymphocyte stimulating capacity of leukemic myeloblasts was studied. The higher the neuraminidase concentration, or the lower the pH was, the more myeloblasts died and the less the myeloblasts stimulated lymphocytes. Myeloblasts treated at a neutral pH and at low enzyme concentrations retained, but did not increase their antigenicity.

Cell Survival↗
PubMed1969

Immunological relationships between the neuraminidases of human and animal influenza viruses.

The neuraminidases of 3 human A2 virus strains-A2/Singapore/1/57, A2/England/76/66 and A2/Hong Kong/1/68-were compared immunologically with those of a number of influenza A virus strains of animal origin (14 avian, 2 equine and 1 porcine). The methods used were enzyme-inhibition tests and immuno-double-diffusion. In enzyme-inhibition tests, the neuraminidases of the A2/57 and A2/66 viruses cross-reacted with those of Turkey/Wisconsin/66, Turkey/Massachusetts/65 and Duck/Italy/574/66 viruses. The enzyme of the Hong Kong variant had a wider spectrum of cross-reactions than did those of the A2/57 and A2/66 viruses. No cross-reaction was detected with Turkey/Massachusetts/65 but the A2/Hong Kong enzyme showed major antigenic similarities with the enzymes of Turkey/Wisconsin/66 and Duck/Italy/574/66 and Duck/Germany/1998/68 viruses. Minor cross-reactions were also detected between the A2/Hong Kong enzyme and those of fowl plague virus, virus "N", Duck/England/56 and Swine/Cambridge/39.The cross-reactions between the enzymes of A2/Hong Kong and Turkey/Wisconsin/66 were confirmed by immunoprecipitin tests. Those between A2/Hong Kong and fowl plague virus, virus "N", Duck/England/56 and Swine/Cambridge/39 could not be confirmed by immunoprecipitation.The finding of antigenic similarities between the enzymes of human and avian influenza A viruses may be of importance in considering the origin of the new antigenic variants of influenza A virus which appear in man.

Animals↗
PubMed1977

[Optimal temperature of enzyme activity and heat resistance of neuraminidases as attenuation markers for influenza viruses].

Neuraminidase activity of virulent and vaccinal strains A/England/42/72, A/Scotland/840/74 and A/Victoria/3/75 assessed at different temperatures did not show significant differences in the temperature optima of enzyme activity. Vaccinal strains were attenuated by APR-8 recombination and selection of mutants resistant to serum inhibitors (Alice, RIT 4025, RIT 4050 strains). On the contrary, differences were found in the thermal inactivation of the neuraminidase between wild and vaccinal strains, the latter being more thermolabile. Increasing from 0.5 to 5.0 mM/1 the Ca++ concentration, an enhancement of the heat stability was observed, more marked for the attenuated strains. The amount of NANA released by 1 hemagglutinating unit varied widely between strains. To be pointed out, however, that within each antigenic variant the vaccinal strain showed a lower enzymatic activity than the corresponding wild strain.

Antigens, Viral↗
PubMedDate not supplied

Rapid enzymologic anti-neuraminidase antibody microtest.

A micro-neuraminidase-inhibition-technique (the Essen NIT) using a glycoprotein as substrate and employing the method of Aminoff for the determination of free N-acetyl neuraminic acid has been developed by our group. The main difference between the micro NI-test and the WHO-method is the mathematical evaluation of AB titer (TI 50) from the investigation of a single dilution only. This procedure is possible, because it could be proved that this reaction follows enzyme-antienzyme kinetics of the Michaelis-Menten type. On the basis of the microliter system and the Michaelis-Menten reaction, the Essen-NI-test has the following economical and technical advantages over the WHO-method: (a) use of only 1/25th volume of the expensive substrate (glycoprotein) per serum in comparison to the WHO-test, (b) investigation of up to 90 sera per technician and day instead of a few sera per technecian and 2 days and (c) testing of nasal washings without further dilution. Regression analysis of test results of antibody determination evaluated with both methods showed a linear correlation with a regression coefficient of about 1. Titers with the WHO-method were 5-10 times higher than with micro NI test, most possibly due to the shorter reaction times. Nevertheless, positive sera were found positive with either test. Strain specificity of neuraminidase could be equally well evaluated with the WHO-method and the Essen-NIT when 5 influenza virus A isolates from Berlin of 1968-1975 were tested against influenza virus X/15 HK immune serum.

Antibodies, Viral↗
PubMed1981

Colony formation by bone marrow cells after incubation with neuraminidase. III. Cell surface repair, homing and growth characteristics of colony forming cells in vivo.

Incubation of bone marrow cells (BMC) with neuraminidase (NA) reduced their ability to form colonies in the spleen of lethally irradiated mice to 25% of control-incubated BMC. Covering of the recipient's receptors for galactosyl residues by infusion of desialated erythrocyte membrane fragments (NA-Efr) fully prevented the reduction of NA-BMC colony formation. Upon retransplantation the desialated CFUS in the spleen of irradiated first recipients could be significantly rescued within 6 h posttransplantation by NA-Efr treatment of secondary recipients. Transplantation experiments, including NA-Efr infused and normal primary and secondary recipients, indicated that repair of the desialated CFUS cell surface probable occurred within 48 h. Establishment of growth curves indicated that desialation of CFUS did not alter their proliferative capacity but probable retarded the cells to proliferate in normal irradiated recipients for about 24 h. This might be the cause of the decreased CFUS content observed in the first recipients' spleen colonies. This delay in the onset of proliferation was not observed in mice with covered galactosyl receptors. The present experiments further indicate that (a) injected desialated CFUS are rapidly sequestrated in the recipient's body; (b) more desialated CFUS initially seed into the spleen than actually form colonies; (c) the spleen probably contains D-Galactose-specific receptors; (d) CFUS may largely restore their surface properties within 24 h following desialation, and (e) the organ distribution of normal CFUS is changed upon injection in NA-Efr infused recipients. Experiments with 51Cr-tagged BMC suggested that the organ distribution of BMC was similarly affected by neuraminidase treatment as that of CFUS.

Animals↗
PubMedDate not supplied

[Determination of the neuraminidase specificity of influenza A and B viruses using a modified lectin test].

A highly purified lectin was obtained from peanuts. The lectin test was modified for determination of the neuraminidase activity of influenza viruses. The test was found to be useful for the determination of the antigenic specificity of neuraminidase. It was found to be 10-50 times as sensitive as the Aminoff test and more economic. The potentials of lectin test are discussed.

Animals↗
PubMed1980

[1H-NMR-spectroscopic evidence for the release of N-acetyl-alpha-D-neuraminic acid as the first product of neuraminidase action (author's transl)].

The 1H-NMR spectroscopy was used to study the anomeric configuration of N-acetyl-D-neuraminic acid released by the action of neuraminidase. The hydrolysis of NeuAcalpha 2 leads to 3 Gal-beta 1 leads to 4Glc (20mM) by the enzymes of Clostridium perfringens and Arthrobacter ureafaciens (50 mU, 150 mU and 800 mU, respectively) in 50mM Na/K-phosphate buffer pD 5.4 was observed by recording the spectra. On the basis of the characteristic signals of the protons at C-3 (alphaNeuAc: delta[H(3e)] = 2.72, delta[H(3a)] = 1.64; betaNeuAc: delta[H(3e)] = 2.25, delta[H(3a)] = 1.84) the product of the enzymatic cleavage was identified to be the N-acetylneuraminic acid in the alpha-anomeric form. Two hypotheses are discussed to explain how the enzymatic hydrolysis may occur and how N-acetyl-alpha-D-neuraminic acid leaves the catalytic site of the neuraminidases with retention of the C-2 configuration.

Arthrobacter↗
PubMed1984

[Enterotoxigenicity and neuraminidase activity of bacteria of the genus Citrobacter].

The data obtained in the study of Citrobacter strains isolated from patients with diarrheal diseases and from healthy persons are presented: enterotoxigenicity was studied in 68 strains, while neuraminidase activity in 41 strains. Among the strains of these groups 9 strains with active enterotoxin and 2 strains producing active neuraminidase were detected. The criteria for subdividing Citrobacter strains according to the activity of their thermolabile enterotoxin are proposed.

Animals↗
PubMed1978

Human renal neuraminidase.

An assay technique for determination of renal neuraminidase (sialidase) activity is described. Consistent and reproducible results were obtained in studies of rat renal tissue. Neuraminidase activity was detected in all human renal specimens studied; however the degree of activity was not related to the presence of renal calculi or infection.

Animals↗