Biomedical subjects

A Nagpurkar

Publications and source records attributed to A Nagpurkar.

At least 19 recordsLinked to original sources

PubMed2004

Cervical spine loading characteristics in a cadaveric C5 corpectomy model using a static and dynamic plate.

Anterior plates are used to increase the initial stability of anterior cervical spine fusions; however, plating has been suggested to cause graft stress shielding, leading to reduced fusion rates. The objectives of this study were to quantify the effects of graft size and plating (static versus dynamic) and the role of the posterior elements on load transmission in anterior cervical fusion. A C5 corpectomy was performed on six human cervical spines (C3-C7). An instrumented height-adjustable graft and dynamic cervical plate were used to measure axial load transmission. Each specimen underwent axial compressive testing with dynamic and static plate configurations, optimal and undersized graft heights, and posterior elements intact and removed. Dynamic plating allowed significantly more load transmission by the graft, particularly in the undersized graft configuration. The posterior elements play a significant role in load transmission.

Aged↗

PubMed1996

Characterization and purification of fucosyltransferases from the cytosol of rat colon.

The occurrence and baseline characteristics of fucosyltransferases (alpha-1,2, alpha-1,3 and alpha-1,4) in the cytosol (soluble) and pellet (membrane-bound) of rat colon have been studied since the fucosylation process is known to alter in colon pathology. All enzymes studied in the colon pellet had higher activity when compared to the cytosol. The colon pellet alpha-1,3 fucosyltransferase preferred desialylated alpha 1-acid glycoprotein as acceptor substrate. Both soluble and membrane-bound enzymes, alpha-1,2 and alpha-1,3 fucosyltransferases, required Mn2+, Mg2+ and Ca2+ for maximum activity but were inactivated by Cu2+ ions. Both soluble alpha-1,2 and alpha-1,3 fucosyltransferases showed optimal activity at pH 6.0, whereas the optimum for their membrane-bound activities were at pH 5.8 and 6.2, respectively. Furthermore, a soluble alpha-1,3 fucosyltransferase from rat colon was purified and during purification the co-presence of alpha-1,3/4 fucosyltransferase was detected. The acceptor of preference for the purified soluble alpha-1,3 fucosyltransferase was desialylated glycoprotein while low molecular weight substrates were poor acceptors. Both the purified fucosyltransferases were inhibited by N-ethylmaleimide. The M(r) values determined by SDS-PAGE electrophoresis of alpha-1,3/4 fucosyltransferase and of alpha-1,3 fucosyltransferase were 68,780 and 40,680 respectively. In conclusion, based on their properties, the purified soluble colon alpha-1,3 fucosyltransferase appeared to be of plasma-type (or FT-I) while the soluble alpha-1,3/4 fucosyltransferase corresponded to Lewis-type or FT-III.

Animals↗

PubMed1996

Specific stimulation of alpha 2-6 sialyltransferase activity by a novel cytosolic factor from rat colon.

A factor present in the 100,000 g supernatant from the homogenate of rat colon stimulated the activity of purified Gal beta 1-4GLcNAc alpha 2,6 sialyltransferase [alpha 2-6ST(N)] from rat liver and alpha 2-6ST(N) from either liver microsomes or Golgi membrane. The stimulation of alpha 2-6ST(N) activity by the colon factor using protein acceptors was about four-fold and highly reproducible when the reaction product of the alpha 2-6ST(N) was assayed by either precipitation or affinity chromatography. In contrast, the colon factor did not stimulate the Gal beta 1-4GlcNAc alpha 2,3 sialyltransferase [alpha 2-3ST (N)], from rat jejunum microsomes or purified Gal beta 1-3GalNAc alpha 2,4 sialyltransferase [alpha 2-3ST (O)] from porcine liver, of purified beta 1,4 galactosyltransferase (GT) from bovine milk. In addition to rat colon, the 100,00 g supernatant from the homogenates of rat brain and kidney also stimulated the alpha 2-6ST(N) activity. The stimulation of alpha 2-6ST(N) by the colon factor resulted in a decrease in the Km (by about two-fold) and an increase in Vmax (about 2- to 3-fold) for desialylated alpha 1 acid glycoprotein and CMP-[14C]N-acetylneuraminic acid. The stimulation of alpha 2-6ST(N) activity by the colon factor was temperature dependent, protease sensitive and was inhibited by CTP, but did not need the presence of either metal ions or detergent. The cytosolic factor was partially purified by ion-exchange chromatography with the retention of the activator activity in the peaks containing low molecular weight proteins, but the activity was lost on attempts to further purification. A specific marked stimulation of the alpha 2-6ST(N) activity by cytosolic factors in certain tissues might suggest a physiological role for these factors in the regulation of alpha 2-5ST(N) activity.

Animals↗

PubMed1994

Rat C-reactive protein causes a charge modification of LDL and stimulates its degradation by macrophages.

We have previously shown the binding of low-density lipoprotein (LDL) to immobilized rat C-reactive protein (CRP) and the formation of a fluid-phase complex between these two proteins. In this report we used immunoelectrophoresis and agarose gel electrophoresis to show increased anodic migration of the LDL particle as a result of the modification of LDL by rat CRP. The degradation of the modified 125I-LDL by rat peritoneal macrophages was increased more than twofold in the presence of rat CRP. The increase in rat CRP-mediated 125I-LDL degradation by macrophages was dependent on the concentrations of 125I-LDL and rat CRP. This increased 125I-LDL degradation was inhibited by phosphorylcholine. In contrast, the degradation of 125I-acetyl-LDL by macrophages was not affected by rat CRP, although acetylated LDL inhibited the rat CRP-stimulated degradation of 125I-LDL. Increasing concentrations of LDL did not affect the degradation of rat 125I-CRP by the macrophages, which suggested that the rat CRP and the modified LDL did not enter the cell as a complex. Our results suggested that the increased degradation of 125I-LDL was caused by the charge modification of 125I-LDL by rat CRP, due to a fluid-phase complex formation between 125I-LDL and rat CRP, and that the degradation involved the scavenger receptor present on the macrophages.

Animals↗

PubMed1993

Degradation of rat C-reactive protein by macrophages.

Rat C-reactive protein (CRP) is a serum glycoprotein belonging to the 'pentraxin' family of proteins. In this study we have shown the specific binding of 125I-CRP to rat peritoneal macrophages at 4 degrees C. This binding was dependent upon incubation time, CRP and cell concentrations, and was not inhibited by either phosphorylcholine or human IgG. At 37 degrees C, the surface-bound 125I-CRP was internalized and degraded. The degradation of 125I-CRP was measured by the formation of 125I-labelled trichloroacetic-acid-soluble CRP peptides by either precipitation assays or by h.p.l.c. of the incubation medium using a gel-filtration column. Since chloroquine and leupeptin inhibited CRP degradation, it was concluded that degradation of CRP occurred in the lysosomal compartment of the macrophage. There was an absolute requirement for the presence of bivalent cations (Ca2+ and Mg2+) in the incubation medium for the binding and degradation of CRP, which could be inhibited by EDTA but not by phosphorylcholine or human IgG. H.p.l.c. analysis of the medium obtained from incubation of macrophages with 125I-CRP revealed the presence of 125I-labelled low-M(r) peptides, the formation of which was dependent upon incubation time.

Animals↗

PubMed1993

Studies on the carbohydrate moiety and on the biosynthesis of rat C-reactive protein.

Rat C-reactive protein (CRP) is a pentameric glycoprotein composed of five apparently identical monomers, two of which form a disulfide-linked dimer (Rasosouli, M., Sambasivam, H., Azadi, P., Dell, A., Morris, H. R., Nagpurkar, A., Mookerjea, S., and Murray, R. K. (1992) J. Biol. Chem. 267, 2947-2954). In this study, the nature of the oligosaccharide chain of rat CRP was investigated by fast atom bombardment-mass spectrometry (FAB-MS), and general features of its biosynthetic pathway were also analyzed. FAB-MS, electrospray-mass spectrometry, and linkage analysis demonstrated that each monomer of rat CRP contained one oligosaccharide chain, predominantly a disialylated biantennary structure, attached to Asn-128. The biosynthesis of rat CRP was studied by immunoprecipitation of CRP synthesized in vitro and by cultured hepatocytes. The results revealed that each monomer of rat CRP was synthesized individually as a single-chain precursor with a cleavable signal sequence. The translocated species was sensitive to digestion by endoglycosidase H (endo H), indicating that it possessed a high mannose oligosaccharide. Rat CRP acquired the ability to bind to phosphorylcholine-Sepharose and to form the dimeric and oligomeric species prior to acquiring resistance to endo H. Studies using tunicamycin revealed that the N-linked oligosaccharide present in rat CRP was not required for formation of its dimeric component, oligomerization, ability to bind to phosphorylcholine, or secretion. The non-glycosylated rat CRP, however, was still able to bind to phosphorylcholine-Sepharose and to be secreted by hepatocytes.

Animals↗

PubMed1992

Evidence for phosphatidylcholine hydrolysis by phospholipase C in rat platelets.

Production of [3H]1,2-dipalmitoylglycerol ([3H]DAG) from 1-palmitoyl-2-[9,10-3H]palmitoyl-sn-glycero-3-phosphocholine and [3H]phosphorylcholine from 1,2-dipalmitoyl-sn-glycero-3-[Me-3H]phosphocholine was studied using sonicated rat platelets. The formation of [3H]DAG and [3H]phosphorylcholine occurred at a comparable rate. [3H]Phosphorylcholine formation was dependent on the concentration of the substrate, platelet sonicates and calcium in the incubation medium. The [3H]phosphorylcholine formation increased in presence of 0.01% deoxycholate and 0.01% Triton X-100. The phosphatidylcholine-phospholipase C (PC-PLC) in the platelet sonicates was recovered in both the supernatant and particulate fractions obtained after ultracentrifugation at 105,000 x g for 1 h. The PC-PLC activity in both fractions was inhibited by 2 mM EDTA. In the presence of 0.01% deoxycholate and 0.01% Triton X-100 the activity in the particulate fraction increased compared to the activity in the supernatant, which was inhibited by 0.01% Triton X-100. The pH optima for PC-PLC in both fractions was between pH 7.2 and 7.6. PC-PLC activity was also found in rabbit and human platelet sonicates, but the activity was significantly lower than in rat platelet sonicates. There was no evidence to suggest presence of phosphatidylcholine-specific phospholipase D activity in rat sonicated platelets. This data, therefore, provides direct evidence for the presence of PC-PLC activity in rat platelets.

Animals↗

PubMed1992

Derivation of the amino acid sequence of rat C-reactive protein from cDNA cloning with additional studies on the nature of its dimeric component.

Rat C-reactive protein (CRP) is unique among mammalian CRPs in being a glycoprotein and in containing a covalently linked dimer in its pentameric structure. To investigate these features, cDNA clones encoding rat CRP were isolated from an expression library, and the primary structure of the protein was derived. Taken along with the results of Northern blotting, we conclude that a single mRNA of approximately 2,500 nucleotides codes for a precursor of rat CRP with a signal sequence of 19 amino acids and a polypeptide of 211 amino acids, the latter sharing extensive homology with human, rabbit, and mouse CRPs. The deduced sequence agreed with results obtained from partial microsequencing and mapping by fast atom bombardment-mass spectrometry. Two potential sites for N-glycosylation (Asn-128 and Asn-147) and a C-terminal heptapeptide (Leu-205 to Ser-211, containing two cysteines at positions 208 and 209) were unique to rat CRP. The protein was also shown to be composed of five apparently identical monomers, two of which form a dimer linked by two interchain disulfide bonds involving Cys-208 and Cys-209. These same cysteines form an intrachain disulfide bond in the other three monomers. The primary structure of rat CRP and the basis of dimer formation have, therefore, been elucidated.

Amino Acid Sequence↗

PubMed1992

Clearance of rat C-reactive protein in vivo and by perfused liver.

The clearance in vivo of rat C-reactive protein (CRP) was studied: (i) in the whole animal and (ii) by using a rat liver perfusion system. Rat CRP is a glycosylated serum protein containing a complex-type biantennary carbohydrate structure on each of its five subunits. The half-life of rat asialo CRP was approximately 5 min. More than 75% of the radioactivity associated with rat asialo CRP and asialo alpha 1-acid glycoprotein (AGP) was recovered in the liver. A small amount of radioactivity (0.8%) associated with rat CRP and rat asialo CRP was found in the lungs. Competitive inhibition of the clearance of 125I-labelled rat asialo CRP from the circulation by asialo AGP was dose dependent, and resulted in a corresponding decrease in the recovery of radioactivity associated with rat asialo CRP in the liver. This indicated that asialo AGP and rat asialo CRP were cleared by the hepatic asialoglycoprotein receptor. This observation was confirmed when the clearance of rat asialo CRP was studied using a rat liver perfusion system. Using this system, the clearance of rat asialo CRP and asialo AGP from the perfusate was inhibited by N-acetylgalactosamine, but not by phosphorylcholine, a ligand through which most of the CRP reactions are mediated. This study provides an example of a circulating serum glycoprotein containing a biantennary carbohydrate structure that is cleared by the asialoglycoprotein receptor.

Animals↗

PubMed1991

Heparin-binding serum protein(s) is required for the protection of sialyltransferase released during the incubation of rat jejunal slices.

Incubation of rat jejunal slices in Krebs-Ringer bicarbonate buffer (KRB) required the presence of heat-inactivated horse serum (HHS) in order to show time-dependent release of sialyltransferase into the medium. Sialyltransferase activity could not be detected in the medium when KRB alone or KRB supplemented with either albumin or glycerol was used in the incubations. The viability of the jejunal slices for up to 4 h of incubation was determined by studying the incorporation of glucosamine and leucine into acid-insoluble proteins. Supplementation of KRB with HHS had no beneficial effect on the rate of incorporation of leucine and glucosamine into proteins. KRB medium obtained after different periods of incubation contained higher trypsin-like activity than KRB medium containing HHS. Various antiproteases present as supplements to KRB resulted in the release of sialyltransferase activity from the jejunal slices. Among these antiproteases, alpha 1-proteinase inhibitor (alpha 1-PI) was the most effective. Also, HHS added to KRB immediately following incubation resulted in partial restoration of sialyltransferase activity in the medium, suggesting the presence of anti-proteolytic factors in HHS. The addition of increasing concentrations of heparin to incubations containing HHS caused a decrease in the medium sialyltransferase activity. The heparin-binding fraction (HBF) from HHS, when added to incubations, was able to protect the sialyltransferase released into medium. However, HHS depleted of its heparin-binding fraction by heparin-agarose affinity chromatography was unable to protect the sialyltransferase. HBF was separated into high- and low-molecular-mass fractions (fractions A and B respectively) by gel-filtration chromatography. The capacity to protect the released sialyltransferase was contained in fraction B. Fraction A contained multiple bands on SDS/PAGE and did not protect the enzyme. Fraction B contained a major protein band on the gel which corresponded to the migration of a similar band in human alpha 1-PI. HBF as well as fraction B isolated from HHS showed anti-trypsin-like activity. The results presented indicate that HHS contains a heparin-binding protein(s) similar to human alpha 1-PI which plays a role in the protection of sialyltransferase released from jejunal slices.

Animals↗

PubMed1991

Isolation of a phosphoryl choline-binding protein from the hemolymph of the snail, Achatina fulica.

A phosphorylcholine-binding protein from the hemolymph of the snail Achatina fulica was purified to near homogeneity using a Sepharose phenylphosphorylcholine affinity column. The protein bound to the affinity column was eluted with 5 mM phosphorylcholine as a single symmetrical peak. The purified protein (400 Kda) contained 35-40% carbohydrate. On SDS-PAGE the protein separated into two bands of 20 and 24 Kda, and had a pI of 5.9. On immunodiffusion, antiserum to the snail phosphorylcholine binding protein did not cross-react against other phosphorylcholine binding proteins, like rat serum phosphorylcholine-binding protein (PCBP), limulus C-reactive protein (CRP), or human CRP. On pretreatment of the snail hemolymph with this antiserum, the hemagglutination titer of the hemolymph was markedly decreased. The purified snail phosphorylcholine binding protein agglutinated rabbit erythrocytes in the absence of divalent cation (Ca+2) but trace amount of Ca+2 increased its binding. The strongest inhibitor of the agglutination reaction was lactose, followed by melibiose and 2-deoxygalactose. The relationships of the snail phosphorylcholine binding protein to other hemolymph agglutinins and to CRPs are discussed in light of common phylogeny.

Animals↗

PubMed1990

Binding of rat serum phosphorylcholine binding protein to platelets.

Rat serum phosphorylcholine binding protein (PCBP), a normal component of rat serum, inhibits in vitro aggregation of rat, rabbit and human platelets by interacting with platelets. In the present study, we have demonstrated the calcium-dependent, specific and saturable binding of 125I-PCBP to rat, rabbit and human platelets. Scatchard analysis of the binding data reveal a class of specific high-affinity binding sites with Kd values of 45.2 +/- 14.9, 26.1 +/- 8.3 and 32.2 +/- 9.9 nM on rat, rabbit and human platelets, respectively. These platelets also expressed a high capacity for binding to 125I-PCBP. The binding of 125I-PCBP to platelets was calcium- and time-dependent, and could be inhibited by phosphorylcholine (IC50 = 5.6 microM). Occupation of these binding sites by PCBP may be responsible for inhibition of platelet aggregation.

Animals↗

PubMed1990

Interaction between rat serum phosphorylcholine binding protein and platelet activating factor.

The binding of rat serum phosphorylcholine binding protein (PCBP) to platelet activating factor (PAF) has been demonstrated using a HPLC-gel filtration technique. The bulk of the bound [3H]-PAF eluted with a higher molecular weight species of PCBP, possibly an aggregated form of PCBP. A smaller amount of [3H]-PAF co-eluted with the major monomeric species of PCBP. Formation of the PCBP-PAF complex was calcium dependent and could be inhibited by phosphorylcholine, suggesting the involvement of the phosphorylcholine binding site on PCBP. Binding of albumin and alpha 1-acid glycoprotein to PAF was not affected by phosphorylcholine or calcium. The specificity of this binding may explain the inhibitory effect of PCBP and related phosphorylcholine binding proteins on PAF induced aggregation of platelets.

Animals↗

PubMed1990

Removal of apoprotein-B-containing lipoproteins by plasmapheresis using immobilized phosphorylcholine-binding protein affinity adsorbent.

Rat serum phosphorylcholine binding protein was earlier shown to bind lipoproteins containing apoproteins B and E from human very low and low density lipoproteins. The present studies were undertaken to show the effectiveness of rat serum phosphorylcholine-binding protein immobilized on Sepharose affinity column to remove apoprotein-B-containing lipoproteins from normal and hypercholesterolemic rabbit plasma, when used in a plasmapheresis system. The maximum in vitro binding of very low and low density lipoproteins from hypercholesterolemic rabbit plasma to the affinity adsorbent was Ca2+ dependent, and the cholesterol bound to the column at the optimum calcium concentration (2.5 mM) was 21% of the total plasma cholesterol applied. The in vivo binding of total cholesterol from normal and hypercholesterolemic rabbit plasma during plasmapheresis ranged from 0.22 to 7.7%. Total mass of cholesterol bound ranged from 3.86 and 27.52 mg at plasma cholesterol concentrations 13.8 and 282 mg/dL, respectively. Most (greater than 95%) of the bound cholesterol was associated with very low and low density lipoproteins. These studies show the ability of immobilized rat serum phosphorylcholine-binding protein to lower the atherogenic apoprotein-B-containing lipoproteins from plasma of hypercholesterolemic rabbits.

Adsorption↗

PubMed1990

Regulation of sialyltransferase activity in intestinal segments of rats.

A differential distribution of sialyltransferase (ST) in different regions of intestine has been shown. Jejunum and ileum homogenates from rats showed almost exclusive presence of alpha-2-3 ST (to Gal in Gal beta-1-4GlcNAc and/or to Gal in Gal beta-1-3GalNAc). In contrast, colon homogenates showed the presence of both alpha-2-3 ST (as above) and alpha-2-6 ST. Incubation of intestinal slices in presence of heat-inactivated horse serum (HHS) showed a time- and temperature-dependent secretion of soluble ST into the medium. Both jejunum and ileum slices showed high rates of secretion of alpha-2-3 ST. Colon slices, though rich in alpha-2-6 ST, secreted only alpha-2-3 ST. Colchicine, an anti-mitotic drug, injected into rats caused about 10-fold increase of the serum ST level. Jejunum slices from colchicine-treated rats showed an increased secretion of alpha-2-6 ST, suggesting that intestine undergoes a change in the expression of normal secretion of alpha-2-3 ST to a secretion of alpha-2-6 ST. The secretion of ST from incubated intestinal slices was inhibited by heparin. Certain protein factors (anti-proteases) in HHS bind to heparin-sepharose column and these protein factors are responsible for causing the secretion of ST into the medium. It has also been found that a supernatant fraction of the colon homogenate activated ST. Gel chromatography on HPLC produced 3-4 protein fractions from the colon cytosol and one of this fraction bearing high molecular weight proteins produced the maximum activation of ST.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effect of rat phosphorylcholine-binding protein on platelet aggregation.

Rat serum phosphorylcholine-binding protein (PCBP), also referred to as rat C-reactive protein, is present in serum under normal physiological conditions. In the present study, PCBP is shown to inhibit, in a dose-dependent manner, ADP- and platelet-activating factor (PAF)-induced platelet aggregation, using either washed rat platelets or platelet-rich plasma from rats or humans. Rat platelets, as expected, were refractory to aggregation by PAF. However, when rabbit antiserum against PCBP was added to rat platelet-rich plasma, it resulted in aggregation of platelets by PAF. PCBP also inhibited the PAF-induced aggregation of human platelets in a dose-dependent manner. The inhibition of ADP-induced platelet aggregation by PCBP was reversed by adding phosphorylcholine. Our results suggest that PCBP present in rat serum could be the cause of the refractory response of rat plasma to PAF. It is possible that PCBP inhibits platelet aggregation by binding to the platelet surface phospholipids.

Adenosine Diphosphate↗

PubMed1987

A study on the selective binding of apoprotein B- and E-containing human plasma lipoproteins to immobilized rat serum phosphorylcholine-binding protein.

Rat serum phosphorylcholine-binding protein (PCBP), a member of the pentraxin family of proteins, was previously shown to bind multilamellar liposomes prepared with egg phosphatidylcholine and lysophosphatidylcholine. The results suggested that the phosphorylcholine groups on the surface of liposomes play an important role in the binding process (Nagpurkar, A., Saxena, U., and Mookerjea, S. (1983) J. Biol Chem. 258, 10518-10523). A study on the binding of human plasma lipoproteins to PCBP immobilized on Sepharose has now been initiated. Very low density lipoproteins were partially bound to a Sepharose-PCBP column, and the bound fraction contained higher concentrations of apoprotein B and E. All the low density lipoproteins applied were bound to the column. In the case of high density lipoproteins, only a small fraction was retained on the column (based on protein analysis), and that bound fraction contained all the apoprotein E and Lp(a) lipoprotein. The binding of very low, low, and high density lipoproteins to Sepharose-PCBP was Ca2+-dependent, and the bound lipoproteins were quantitatively eluted by a phosphorylcholine gradient. Apoprotein B and E were also bound when whole human plasma was applied to Sepharose-PCBP. The effect of selective modification of lysine residues by acetoacetylation and of arginine residues by cyclohexanedione on the binding of low density lipoproteins to Sepharose-PCBP was examined. Modification of arginyl residues resulted in marked reduction of binding, whereas modification of lysine had no effect. Removal of sialic acid from PCBP also had no effect on the binding of low density lipoproteins to immobilized-desialylated PCBP column. The preferential binding of apoprotein B- and E-containing lipoproteins to Sepharose-PCBP indicates a possible physiological role of PCBP and other similar circulating phosphorylcholine-binding proteins of the pentraxin family in lipoprotein metabolism.

Animals↗

PubMed1987

Characterization of serum, liver, and intestinal sialyltransferases from rats treated with colchicine.

A modified high pressure liquid chromatographic method using lactose (Gal beta 1----4Glc) as an exogenous acceptor has been used to characterize the sialyltransferases known to increase in the serum of colchicine-treated rats. The results show a 10-fold increase of Gal beta 1----4GlcNAc alpha 2----6 sialyltransferase (alpha 2----6 ST), whereas the Gal beta 1----3GlcNAc alpha 2----3 sialyltransferase showed only 1.6-fold increase in the serum after 17 h of colchicine treatment. The sialyltransferase activity in serum using exogenous desialylated, alpha 1-acid glycoprotein as acceptor also showed an eightfold increase. In liver homogenate and Golgi membrane, the sialyltransferase activity when assayed with desialylated alpha 1-acid glycoprotein as acceptor showed a slight decrease after 4 h, but returned to normal level after 17 h. A similar trend was seen when the two transferases were assayed with lactose as acceptor. The antiserum to rat alpha 2----6 ST inhibited the sialyltransferase activity in serum, liver, and jejunal incubation medium. Jejunal sections from rats treated with colchicine for 4 h in presence of heated serum showed a decrease of sialyltransferase, with consequent increase of the alpha 2----6 ST enzyme activity in the medium. This result suggests that intestinal tissue could be a source of increased serum enzyme activity in colchicine treatment.

Animals↗