Effect of hydrocortisone on the desialylation of intestinal brush-border enzymes of the rat during postnatal development

Hydrocortisone acetate or hemisuccinate (75 mg/kg body mass) applied to rats i.m. and/or s.c. on the 9th and 10th postnatal days causes a precocious decrease of sialic acid content of the small intestinal brush-border membrane. On the 15th postnatal day the bound sialic acid of the whole membrane fraction drops to almost half of the values of control animals and to one third of the control values for the papain-solubilized membrane proteins. The hydrocortisone effect is manifested on isoelectric focusing zymograms by a faster increase of pI of the solubilized brush-border enzymes on the 12th and 15th postnatal days.

The carbohydrates of mouse hepatitis virus (MHV) A59: structures of the O-glycosidically linked oligosaccharides of glycoprotein E1

Two size classes of O-glycosidically linked oligosaccharides were liberated from glycoprotein E1 of mouse hepatitis virus (MHV) A59 by reductive beta-elimination and separated by h.p.l.c. The structures of the reduced oligosaccharides were determined by successive exoglycosidase digestions and by methylation analyses involving combined capillary gas chromatography-mass spectrometry and mass fragmentography after chemical ionization with ammonia. Oligosaccharide A (Neu5Ac alpha 2----3 Gal beta 1----3 GalNAc) comprised 35% of the total carbohydrate side chains, while the remaining 65% of the oligosaccharides of E1 had the branched structure B: Neu5Ac alpha 2----3 Gal beta 1----3 (Neu5Ac alpha 2----6) GalNAc. Both oligosaccharides were linked to the E1 polypeptide via N-acetylgalactosamine, and 20% of the sialic acids present in E1 glycopeptides were found to consist of N-acetyl-9-mono-O-acetylneuraminic acid. The reported structures of the O-linked glycans are discussed in the context of the amino acid sequence of E1, which exhibits a cluster of four hydroxyamino acids (Ser-Ser-Thr-Thr) as potential O-glycosylation sites at the amino terminus. Oligosaccharides with identical structures and an identical O-glycosylated tetrapeptide sequence are present in the blood group M-active glycophorin A of the human erythrocyte membrane.

Isoelectric forms of clusterin isolated from ram rete testis fluid and from secretions of primary cultures of ram and rat Sertoli-cell-enriched preparations

Clusterin, a cell aggregating factor isolated from ram rete testis fluid (RTF), is shown to contain 14.7% hexoses, 13.6% glucosamine, and 7.9% sialic acid. The isoelectric point (pI) of the predominant electrophoretic form of clusterin from ram RTF is 3.7. After treatment with neuraminidase, the pI values become more basic, with the majority of the material being eluted from a chromatofocusing column at pH values between 4.9 and 5.1. Intact clusterin binds quantitatively to wheat germ agglutinin - Sepharose 6 MB, but after treatment with neuraminidase only 49% specifically binds. Clusterin isolated from proteins secreted by primary cultures of ram Sertoli-cell-enriched preparations was shown to have properties similar to those of intact clusterin isolated from ram RTF. In contrast, clusterin isolated from proteins secreted by primary cultures of rat Sertoli- or granulosa-cell-enriched preparations has isoelectric forms which more closely resemble those of neuraminidase-treated ram clusterin.

Histochemical characterization of mucosubstances in synovial sarcoma

Six cases of synovial sarcoma were examined histochemically in order to clarify the components of mucosubstances in the tumor tissues. The tumors were classified into 1) monophasic type, 2) predominantly monophasic type with focal biphasic differentiation, and 3) biphasic type. The former two groups and sarcomatous areas in the biphasic tumors contained various amounts of hyaluronic acid, chondroitin sulfate, and, in some cases, heparitin sulfate. By contrast, the epithelioid regions in the biphasic-type tumors had periodic acid-Schiff-positive glycoproteins which contained various amounts of sialic acid, in addition to hyaluronic acid and chondroitin sulfate. The significance of the presence of glycoproteins in the mesenchymal tumors is emphasized. It seems likely that the synovial sarcomas contain various kinds of mucosubstances and that sensitivity to hyaluronidase treatment is not necessarily the diagnostic criterion of synovial sarcoma.

Histochemical identification of side chain substituted O-acylated sialic acids: the PAT-KOH-Bh-PAS and the PAPT-KOH-Bh-PAS procedures

Two new methods, based on the original periodic acid-Thionin Schiff-saponification-periodic acid-Basic Fuchsin Schiff (PAT-KOH-PAS) technique of Culling et al. (1976), have been devised for the histochemical identification of side-chain O-acylated sialic acids. In the first of these, the periodic acid-Thionin Schiff-saponification-borohydride reduction-periodic acid-Basic Fuchsin Schiff (PAT-KOH-Bh-PAS) procedure, the specificity of the original PAT-KOH-PAS technique was improved by: (a) extending, when necessary, the initial period of periodate oxidation, (b) increasing the period of exposure to Thionin Schiff reagent from 30 min to 4 h, (c) using a Thionin Schiff reagent prepared by a different method, (d) interposing a borohydride reduction step between the saponification and PAS steps and, (e) extending the period of oxidation in the final PAS step from 10 to 30 min. In the second procedure, the periodic acid-phenylhydrazine-Thionin Schiff-borohydride reduction-periodic acid-Basic Fuchsin Schiff (PAPT-KOH-Bh-PAS), based on the periodic acid-phenylhydrazine-Schiff (PAPS) technique of Spicer (1961), blue Thionin Schiff staining was confined to sialic acid residues with oxidizable side chain vicinal diols by interposing a treatment with 0.5% (w/v) aqueous phenylhydrazine hydrochloride for 2 h at room temperature between the initial periodic acid oxidation and the Thionin Schiff steps of the PAT-KOH-Bh-PAS procedure. These procedures are discussed within the general framework of the methods available for the histochemical identification of side-chain O-acylated sialic acids.

Distribution of carbohydrate residues in normal skin

Sections of biopsies of normal skin obtained from 11 individuals were incubated with 8 lectins using an avidin-biotin complex (ABC). All sections when incubated with the appropriate lectin showed the presence of the following carbohydrate residues: L-fucose, beta-(1-4)-D-GlcNAc)2 (N-acetylglucosamine), acetylneuraminic acid, Gal-beta-(1-3)-GalNAc (N-acetyl-galactosamine), beta-D-galactose, alpha-D-glucose, and alpha-D-mannose. In addition, sections of individuals with blood group A showed alpha-D-GalNAc and sections of individuals with blood group B showed alpha-D-galactose. In the stratum (str.) basale, carbohydrates were present in small quantities, but as the cells matured and moved upward, the incorporation of carbohydrates into the cell membranes increased considerably. In the str. granulosum, lectin reactivity was absent in many sections, probably due to masking by phospholipids. The dark cells in the eccrine glands showed reactivity with all lectins except in the one nonsecretor with blood group A1, whose dark cells showed no L-fucose and alpha-D-GalNAc. The endothelial cells of the blood vessels showed lectin reactivity except when incubated with concanavalin A. The sebaceous glands showed both cytoplasmic and membrane staining when incubated with various lectins.

Cellular myeloperoxidase activity in human monocytes stimulated by hyposialylated immunoglobulins and rheumatoid factors

When hyposialylated , immunoglobulins become immunogenic and tend to form aggregates. In pursuit of the possibility that hyposialylated immunoglobulins (hs-Ig) can trigger human mononuclear phagocytic cells, we have investigated the effects of such hs-Ig on the myeloperoxidase (MPO) activity of these cells. The incubation of human monocytes with aggregated hs-Ig leads to the decrease of intracellular MPO activity. This decrease is dependent on the incubation time, on the amount of hs-Ig added, and on the degree of aggregation. Incubation with unaggregated hs-Ig has a similar effect, thus providing evidence that the loss of sialic acid residues per se is enough to render these molecules capable of decreasing the MPO content of phagocytic cells. Furthermore, human rheumatoid factors, isolated from the sera of rheumatoid arthritis patients, and previously characterized as hyposailylated Ig, interact in the same way with monocytes in triggering the MPO decrease. These observations imply that hs-Ig may be considered as active stimuli in the induction of inflammatory processes, through the initiation of oxidative reactions.

Effect of modification of sialic acid on enzymic hydrolysis of gangliosides GM1 and GM2

In order to understand the mechanism of action of the activator proteins for the enzymic hydrolysis of GM1 (GM1-activator; Li, S.-C. and Li, Y.-T. (1976) J. Biol. Chem. 251, 1159-1163; for ganglioside designations, see Svennerholm, L. (1963) J. Neurochem. 10, 613) and GM2 (GM2-activator; Li, S.-C., Hirabayashi, Y., and Li, Y.-T. (1981) J. Biol. Chem. 256, 6234-6240), we have studied the effect of chemical modifications of GM1 and GM2 on their susceptibility to the activator-assisted enzymic hydrolysis. Chemically modified GM1 and GM2 were prepared by methyl esterification (Me-GM1 or Me-GM2) and reduction (HO-GM1 or HO-GM2) of the -COO- group of the sialic acid. Me-GM1 and HO-GM1 could be hydrolyzed by human hepatic beta-galactosidase in the presence of GM1-activator at rates comparable to that of the native GM1. However, in contrast to native GM2, Me-GM2 and HO-GM2 were resistant to the hydrolysis by human hepatic beta-hexosaminidase A in the presence of GM2-activator. When GM2-activator was replaced by sodium taurodeoxycholate, the native GM2 and both modified GM2 could be hydrolyzed by beta-hexosaminidase A. These results suggest that the carboxyl function of sialic acid in GM1 is not vital for beta-galactosidase or GM1-activator to carry out the cleavage of the terminal Gal. In the case of GM2 hydrolysis, the carboxyl function of sialic acid is involved in the interaction with GM2-activator. Our results also indicate that the mode of action of GM1-activator is different from that of GM2-activator and that the action of GM2-activator is different from that of sodium taurodeoxycholate.

Shedding of gangliosides from tumor cells depends on cell density

The ganglioside composition of mouse ascites hepatoma ( MAH ) cells, the ascites fluid and cell-conditioned media were determined and found to be qualitatively identical, but quantitatively different. The ganglioside content of the ascites fluid and the medium conditioned by MAH -cells at the native cell concentration (10(8) cells/ml) comprised respectively 74.9% and 23% of the cell-associated gangliosides. When incubated at lower cell-density (10(6) cells/ml) the cells were found to be release about three-times higher amounts of ganglioside per cell than during incubation at the native concentration. Centrifugation of the dense-cell-conditioned medium revealed the major part of the released gangliosides to be associated with a 150000 X g pellet that probably contains shed plasma membrane fragments. In the 150000 X g pellet of the extracellular fluids the relative content of the most polar cell ganglioside corresponding chromatographically to GT1b was about ten-times higher than in the cells. The possibility is raised that the more intense shedding of gangliosides from less crowded MAH cells may play a role in the self protection of the tumor from host immune rejection during initial stages of growth.

Molecular weight and charge heterogeneity of Thy-1 glycoprotein in different populations of T-cells

Molecular weight and charge microheterogeneity of Thy-1 glycoprotein expressed on different T-cell populations were compared by two-dimensional gel electrophoresis and endoglycosidase treatment. Thy-1 was immunoprecipitated from detergent lysates of radioiodinated T-cells of spleens, lymph nodes, Peyer's patches, peripheral blood, IL-2-cultured thymocytes and peanut agglutinin (PNA) separated thymocytes. In general, thymocytes and IL-2-cultured thymocytes expressed the highest levels of Thy-1 with a large Mr and charge variation. The Thy-1 of these cells was basic and contained low levels of sialic acid. On the other hand, peripheral T-lymphocytes exhibited a restricted Mr and more limited charge heterogeneity with higher amounts of sialic acid. The Thy-1 glycoprotein of mature, low Thy-1 PNA- thymocytes had Mr and charge heterogeneity identical to peripheral T-lymphocytes. The Mr and charge variation of immature PNA+ thymocytes was essentially identical to that of whole thymocytes. The molecular source of Mr heterogeneity in thymocyte Thy-1 and restricted Mr in lymph node Thy-1 was studied by analysis with endoglycosidase-H (Endo-H) and Endo-D. The results of Endo-H digestion showed that most of the Thy-1 polypeptides from both thymocyte and lymph node contained one high-mannose type oligosaccharide which was relatively small and not heterogeneous with respect to Mr. The complex-type oligosaccharides (Endo-D-sensitive) were larger and were responsible for the broad Mr-heterogeneity found in thymocyte Thy-1. Both thymocyte and lymph node Thy-1 generally appear to contain three N-linked oligosaccharides (one high-mannose and two complex) and sequential hydrolysis with Endo-H and Endo-D resulted in an unglycosylated polypeptide with an Mr of approx. 12,500.

Delayed afterdepolarisations and triggered activity in canine Purkinje fibres treated with neuraminidase

We investigated the electrophysiological alterations induced by the removal of sialic acid from the sarcolemma in canine Purkinje fibres. About 70% of total sialic acid content of Purkinje fibres was removed by 120 min of exposure to neuraminidase (1 U X ml-1). The treatment with neuraminidase did not change any of the action potential characteristics at normal Ca2+ concentration (2.7 mmol X litre-1). However, action potential duration and maximum upstroke velocity of phase zero of the action potential were reduced to a greater degree in neuraminidase-treated Purkinje fibres than in non-treated controls at high Ca2+ concentration (8.1 mmol X litre-1). At high Ca2+ concentration, delayed afterdepolarisations were induced in five out of nine neuraminidase-treated Purkinje fibres and triggered activity was observed in two, when driven in trains of 20 stimuli of different cycle length (1000 to 180 ms). No discernible delayed afterdepolarisations were observed in nine non-treated control Purkinje fibres. In addition, the amplitude of delayed afterdepolarisations induced by ouabain (0.2 mumol X litre-1) in neuraminidase-treated Purkinje fibres was larger than non-treated controls. These findings suggest that sialic acid residues of glycocalyx function as a kind of barrier to Ca2+ influx.

The lubricating activity of human synovial fluids

The lubricating abilities of human synovial fluids were measured using a rotating cartilage-on-glass apparatus. A total of 247 human fluids were lubrication-tested. Of these, 20 of the 180 knee fluids from patients with degenerative/traumatic joint disease lubricated less well than normal bovine synovial fluid. The remainder of the fluids from the knee and other joints were equivalent to normal bovine synovial fluid in their lubricating properties. The concentrations of hyaluronic acid, protein, and sialic acid and the relative viscosity of 117 human fluid samples were determined, but no relationships between the gross composition and the lubricating abilities were apparent.

[Structure of lymphoma gangliosides in EL-4 mice]

The structure of the major gangliosides from murine lymphoma EL-4 was established by acid hydrolysis, methanolysis, methylation analysis, neuraminidase treatment and chromium trioxide oxidation. Two of these gangliosides were identified as the N-acetyl and N-glycoloyl forms of the GM2 ganglioside. The third ganglioside making up to 40% of the total ganglioside pool contained two sialic acid residues and was identified as a GD2 ganglioside which up to now had not been reported in extraneural tissues.

Studies of the degraded carrageenan-induced colitis of rabbits. I. Changes in the epithelial glycoprotein O-acylated sialic acids associated with ulceration

Ulceration of the large intestine, induced in New Zealand white rabbits by the administration of 1% w/v degraded carrageenan for periods of up to nine weeks, was studied by a combination of histochemical and chemical procedures for the identification of O-acylated sialic acid. The onset of the disease was rapid, visible faecal blood being observed within five days. Caecal ulceration was diffuse throughout the mucosa being more prominent and frequent on the transverse folds. In some cases large, discrete ulcers were observed in the rectal portion of the lower colon, while in a small number of cases there were ulcers at the caecal end of the upper colon. The ulceration was characterized by oedema, congestion, haemorrhage, inflammation and mucosal ulceration. The inflammatory exudate consisted of macrophages, lymphocytes, a few plasma cells and, in animals treated for a long period, aggregates of eosinophils. The ulceration was associated with a marked reduction in the proportion of the caecal epithelial glycoprotein sialic acids which were neuraminidase-resistant and/or substituted in the side chain. Histochemical studies indicated that changes in side chain substitution were more marked at the margins of the ulcers and could be observed in sections of colon that showed no evidence of ulceration.

The anti-ulcerogenic activity of the unripe plantain banana (Musa species)

Various preparations of dried unripe plantain banana were found to be anti-ulcerogenic against aspirin-induced ulceration in the rat and were effective both as a prophylactic treatment and in healing ulcers already induced by aspirin. Ripe fruit bananas were inactive. The active factor(s) were water soluble and were concentrated by extraction to approximately three hundred times that in the dried banana powder. The anti-ulcerogenic action of banana preparations appears to be due to their ability to stimulate the growth of gastric mucosa. Aluminium hydroxide, cimetidine, prostaglandin E2, N6, O2-dibutyryl adenosine 3',5' cyclic monophosphate but not 5-hydroxytryptamine were also anti-ulcerogenic when used prophylactically in rats but were ineffective in healing ulcers already formed by aspirin. These substances did not stimulate the growth of gastric mucosa.

Synthesis and conformational studies of 2-beta-chloro, 1-alpha-fluoro, and 2-beta-fluoro derivatives of 2-deoxy-N-acetyl-neuraminic acid

5-Acetamido-4,7,8,9-tetra-O-acetyl-2,3,5-trideoxy-2-fluoro-D-glycero-alp ha- and -beta-D- galacto -2- nonulosonic acid methyl esters and the beta-chloro analog were synthesized from N-acetylneuraminic acid. Their 1H- and 13C-n.m.r.spectra were completely assigned by using single-frequency decoupling, off-resonance decoupling, and spin-simulation programs. Bond angles estimated from the 1H coupling-constants indicate that all of the compounds adopt the 2C5 (L) conformation with minor conformational differences in the C3 side chain. 5-Acetamido-2,3,5,-tri-deoxy-2-fluoro-D-glycero-alpha- and -beta-D- galacto -2- nonulosonic acid and their methyl esters were also prepared.

Identification and characterization of podocalyxin--the major sialoprotein of the renal glomerular epithelial cell

The glomerular epithelial polyanion is a specialized cell surface component found on renal glomerular epithelial cells (podocytes) that is rich in sialoprotein(s), as detected by staining with cationic dyes (colloidal iron, alcian blue) and wheat germ agglutinin (WGA). We have isolated rat glomeruli and analyzed their protein composition by SDS PAGE in 5-10% gradient gels. When the gels were stained with alcian blue or "Stains All," a single band with an apparent Mr of 140,000 was detected that also stained very prominently with silver, but not with Coomassie Blue. This band predominated in fluorograms of gels of isolated glomeruli that had been labeled in their sialic acid residues by periodate-[3H]borohydride. In lectin overlays, the 140-kilodalton (kd) band was virtually the only one that bound [125I]wheat germ agglutinin, and this binding could be prevented by predigestion with neuraminidase. [125I]Peanut lectin bound exclusively to the 140-kd band after neuraminidase treatment. An antibody was prepared that specifically recognizes only the 140-kd band by immunoprecipitation and immuneoverlay. By immunoperoxidase and immunogold techniques, it was localized to the surface coat of the glomerular epithelium and, less extensively, to that of endothelial cells. When analyzed (after electroelution from preparative SDS gels), the 140-kd band was found to contain approximately 20% hexose and approximately 4.5% sialic acid. These findings indicate that the 140-kd protein is the major sialoprotein of the glomerulus, and it is the only component of glomerular lysates with an affinity for cationic dyes and lectins identical to that defined histochemically for the epithelial polyanion in situ. Since this molecule is a major component of the cell coat or glycocalyx of the podocytes, we have called it "podocalyxin."

Positive and negative ion fast atom bombardment mass spectrometry of glycosphingolipids. Discrimination of the positional isomers of gangliosides with sialic acids

High molecular weight gangliosides (GD1a, GD1b, GT1a, and GT1b) and neutral glycosphingolipids (Forssman antigen, globoside, and CTH) containing various fatty acids were analyzed by positive and negative ion fast atom bombardment mass spectrometry (POS-FAB-MS and NEG-FAB-MS) without any derivatization. NEG-FAB-MS of the molecules gave intense peaks of the molecular ion species, (M-H)-, and many fragment ions useful for the elucidation of carbohydrate structure were also detected with significant intensity. The fragment ions were assessed to be cleaved at the glycosidic linkages sequentially from the non-reducing end with or without the ceramide portion and it was possible to distinguish structural isomers having different binding positions of sialic acid. All molecular ion species of neutral glycosphingolipids with various fatty acids were detected at intensities that were in accordance with the relative abundance of the fatty acids.

Structural studies on the major oligosaccharides in a variant surface glycoprotein of Trypanosoma congolense

The carbohydrate moieties in the four isotypes of a variant surface glycoprotein from Trypanosoma congolense were analyzed. All variant surface glycoprotein isotypes were found to contain up to 15% by weight of D-galactose, D-mannose, and N-acetyl-D-glucosamine in molar ratios approaching 1:3.2:3.9 (isotypes I-III) or 1:2.4:2.4 (isotype IV); in addition, the presence of sialic acid could be demonstrated. After metabolic labelling with D-[6-3H]glucosamine, the four isoglycoproteins were successively digested with pronase and with endo-beta-N-acetylglucosaminidase H. Up to two thirds of the oligosaccharides were thus liberated and were separated by gel filtration, and by high performance liquid chromatography. Using methylation, gas chromatography, mass spectrometry and digestion with alpha-mannosidase, they were shown to be mainly typical oligomannosidic oligosaccharides of size classes Man5GlcNAc to Man9GlcNAc. The residual glycans were liberated by hydrazinolysis, and were fractionated by serotonin affinity chromatography. After separation by gel filtration, the neutral oligosaccharides from isotype I were subjected to methylation analysis and successive exoglycosidase digestions. They were found to be biantennary oligosaccharides of the N-acetyllactosaminic type: (GalGlcNAc)2Man3GlcNAc1-2. Only about 30% of the sialylated glycans were susceptible to neuraminidases. The T. congolense variant surface glycoprotein studied here contains mainly high mannose and biantennary 'complex' oligosaccharides as found in many other eukaryotic glycoproteins, except that they seem to carry unusually substituted/linked sialic acid residues.

Sialidase assay by luminescence in the low picomole-range of sialic acid. Its application to the measurement of this activity in influenza virus

A new procedure for a sialidase assay, by bioluminescence, has been developed. The substrate, N- acetylneuraminyllactose (sialyllactose), hydrolysed by the sialidase activity, releases lactose. This lactose is hydrolysed with beta-galactosidase. The released galactose is oxidized with galactose dehydrogenase and NAD. The NADH produced in the last step is measured by a luminescence system, coupling two enzymes, NAD(P)H dehydrogenase (FMN) and luciferase. This microassay, which is specific, rapid, simple and ultra-sensitive, is a measure for amounts as little as (at least) 5 pmol of N-acetylneuraminic acid (corresponding to 0.15 ng of the released sialic acid). It uses commercialized reagents (non-radioisotopic) and avoids interferences common in other procedures. This method has been used for measuring sialidase activity directly on intact virus, avoiding inconvenient modifications produced in the extraction of the enzyme. The specific activity of sialidase of influenza virus X31 (H3N2), determined by this procedure, is 0.65 U/mg of total virus protein.

Effects of nitrogen dioxide on red blood cells of rats: alterations of cell membrane components and populational changes of red blood cells during in vivo exposure to NO2

Male Wistar rats were exposed to 4 ppm NO2 for 10 days in order to examine the relationship between the changes in components of red cell membranes and alterations of erythrocyte population. Na+, K+-ATPase activity of red blood cell membranes of exposed animals showed a significantly higher value than that of the control at the first and fourth days of exposure and then decreased to under the control value at the seventh day. In order to examine changes in erythrocyte population, red blood cells were fractionated into four fractions according to their density using Dextran density centrifugation. The alteration of the percentage of lowest-density cells (fraction IV) of exposed animals was completely consistent with that of Na+,K+-ATPase activity in addition to that of the sialic acid content as described in a previous report (K. Kaya, T. Miura, and K. Kubota (1980). Environ. Res. 23, 397-409.). The percentage of fraction IV was 1.43- (P less than 0.05) and 1.68-fold (P less than 0.01) those of the control at the first and fourth days of exposure, respectively, and then decreased to under the control value at the seventh day. This decrease accompanied increases in the percentages of higher-density cells (fractions I and II). Examination of subfractions of red blood cells showed that Na+,K+-ATPase activity and the sialic acid content of three fractions with lower densities have higher values in exposed animals than in the control 1 day after exposure to NO2. Based on these results, it is concluded that increases in Na+,K+-ATPase activity and the sialic acid content occurring 1 day after exposure to 4 ppm NO2 were caused by elevated levels of these components in three fractions with lower densities as well as by an increase in the percentage of lowest-density cells in the erythrocyte population. It was also suggested that NO2 inhalation accelerated aging of erythrocytes with respect to density. The change in Ca2+,Mg2+-ATPase activity, in addition to that in the hexose content as described in a previous report (Kaya et al., 1980), was different from those in the sialic acid content and Na+,K+-ATPase activity. Ca2+,Mg2+-ATPase activity and the hexose content of exposed animals showed slightly reduced values 1 day after exposure to NO2. In all subfractions of red blood cells these values were slightly lower in exposed animals than in the controls. Therefore, reduction in Ca2+,Mg2+-ATPase activity and the hexose content is not due to changes in erythrocyte population.

[Neuraminidase activity of staphylococci]

141 S. aureus and S. epidermidis strains, isolated from the personnel of obstetric wards by taking smears from the anterior sections of the nose, have been tested for their capacity for neuraminidase production. The test has been carried out by the thiobarbiturate method in a medium with ovomucin added. Neuraminidase activity has been found to be characteristic mostly of S. aureus strains isolated from constant carriers.

Use of prokaryotic-derived probes to identify poly(sialic acid) in neonatal neuronal membranes

Three prokaryotic-derived probes to identify and study the temporal expression of polysialosyl units in neuronal tissue have been developed. A polyclonal antibody, a bacteriophage-derived endo-neuraminidase, and an Escherichia coli K1 sialyltransferase are all specific for either recognizing or synthesizing poly(sialic acid) containing alpha-2,8-ketosidic linkages. Polysialosyl immunoreactivity with apparent Mr values of 180,000-240,000 was specific for developing neuronal tissue; it was not detected in neonatal liver or kidney or in adult brain tissue. The developmentally regulated disappearance in poly(sialic acid) is consistent with the probes described here recognizing the polysialosyl carbohydrate units of a neuronal cell adhesion molecule (N-CAM). Treatment of brain extracts with a bacteriophage-derived endo-neuraminidase specific for alpha-2,8-linked polysialosyl units abolished the immunoreactivity. The material solubilized by endo-neuraminidase was isolated, reduced with borotritide, and shown to contain oligomers of sialic acid with three to six sialyl units. Treatment of the 3H-labeled oligosialic acid with exo-neuraminidase quantitatively converted the radioactivity to sialitol, establishing that the brain-derived oligomers were composed solely of sialic acid. A membranous sialytransferase from E. coli K1 that can transfer sialic acid to exogenous acceptors of oligo- or poly(sialic acid) also recognized rat brain membranes, further substantiating the presence of poly(sialic acid) in rat brain. This conclusion was confirmed by using a mutant of E. coli K1 that was defective in the synthesis of poly(sialic acid) and could only transfer sialic acid to exogenous acceptors of oligo- or poly(sialic acid). Sialyl polymer synthesis was restored in the mutant when brain membranes were added as exogenous acceptor.