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PubMedDate not supplied

Cellular uptake and photocytotoxicity of glycoconjugated porphyrins in HeLa cells.

Thirty-two glycoconjugated porphyrins were synthesized by a modification of Lindsey method in the presence of Zn(OAc)(2).2H(2)O as a template. The Zn(2+) ion template strategy improved the yield about three-fold in the case of meta-substituted tetraphenylporphyrins. In addition, free-base porphyrins were obtained almost quantitatively by demetalation with 4 M HCl. Sixteen deacetylated glycoconjugated porphyrins were tested as candidate photodynamic therapy (PDT) drugs using HeLa cells. Most of the deacetylated glycoconjugated porphyrins showed higher cellular uptake than tetraphenylporphyrin tetrasulfonic acid (TPPS), and 5,10,15,20-tetrakis[4-(beta-D-arabinopyranosyloxy)phenyl]porphyrin (p-5d) in particular showed 18.5-fold higher uptake than TPPS. The photocytotoxicity of 5,10,15,20-tetrakis[4-(beta-D-glucopyranosyloxy)phenyl]porphyrin (p-5a), p-5d and TPPS was examined with HeLa cells, using a light dose of 16 J/cm(2). These photosensitizers had no cytotoxicity in the dark, but their photocytotoxicity increased in the order of TPPS < p-5a < p-5d. These results suggest p-5d is a good candidate for a PDT drug.

Biological Transport↗
PubMed1980

Progesterone effect on the biosynthesis of glycoconjugates, specifically of sulfated glycoprotein, in the endometrium of rabbit uterus.

The endometrial scrapings obtained from the uteri of estrogen-progesterone-treated and estrogen-treated rabbits were incubated with N-acetyl-D-[1-3H]glucosamine and [35S]sulfate, and then the incubation medium (M-Fr) was separated from the tissue. The tissue was subsequently homogenized exhaustively in 0.25 M sucrose, and the insoluble residue (R-Fr) was separated. The supernatant at 8,5000 X g for 10 min of the homogenate was subjected to subcellular fractionation by discontinuous sucrose gradient ultracentrifugation, and a Golgi-rich fraction (G-Fr) was obtained. Crude glycoconjugates (glycosaminoglycans and glycoproteins) were then separated from M-Fr, R-Fr and G-Fr after pronase digestion. The amounts of the radioactivities incorporated into these glycoconjugates suggested that progesterone markedly suppressed the estrogen effect within 6 hr in R-Fr and G-Fr, whereas the suppression slightly delayed in M-Fr. The amounts of the radioactivities incorporated into acidic GC, which obtained by CPC-precipitation of the crude GC after digestion with crude heparinase, indicated that the biosynthesis of the CPC-precipitable sulfated glycoproteins was almost completely ceased by progesterone, although other glycoconjugates were still actively synthesized under the progesteronic condition.

Animals↗
PubMedDate not supplied

Glycoconjugates, cellular differentiation, and congenital glaucoma.

Studies of congenital glaucoma have described and debated the disease process in cellular and structural terms, yet the functional aspects of the disease remain poorly understood. This paper presents an attempt to look at the disease from a different perspective: the role of glycoconjugates and their influence on morphogenesis of the corneoscleral angle. Extracellular and cell-surface complex carbohydrates and trabecular meshwork development were observed in normal C-57 BL/6J mice with light and electron microscopy. Lectin-stained fixed tissues were evaluated by fluorescein light microscopy and with computer-controlled scanning microspectrophotometry. The appearance and type of specific glycoconjugates was related to morphogenesis and differentiation, with specific reference to the development of the trabecular meshwork. Our results suggest that glycoconjugates are: (1) important in the morphogenesis of the corneoscleral angle, and (2) provide some of the required signals for the differentiation of the cells of the trabecular meshwork. These findings emphasize the possibility that a complex series of morphological and biological events in the normal development of the trabecular meshwork ultimately leads to a functionally competent trabecular meshwork, that is, capacitation.

Animals↗
PubMed2002

Antigen presentation by CD1d contributes to the amplification of Th2 responses to Schistosoma mansoni glycoconjugates in mice.

During murine schistosomiasis, there is a gradual switch from a predominant Th1 cytokine response to a Th2-dominated response after egg laying, an event that favors the formation of granuloma around viable eggs. Egg-derived glycoconjugates, including glycolipids, may play a crucial role in this phenomenon. In this study, we used a model of dendritic cell sensitization to study the role of egg glycoconjugates in the induction of specific immune response to soluble egg Ag (SEA) and to investigate the possibility that CD1d, a molecule implicated in glycolipid presentation, may be involved in such a phenomenon. We show that, when captured, processed, and presented to naive T lymphocytes by dendritic cells, egg, but not larval, Ag skew the immune response toward a Th2 response. Periodate treatment reversed this effect, indicating that the sugar moiety of SEA is important in this phenomenon. Using DC treated ex vivo with a neutralizing anti-CD1d Ab or isolated from CD1d knockout mice, we show that CD1d is crucial in the priming of SEA-specific Th2 lymphocytes. We then evaluated the contribution of CD1d on the development of the SEA-specific immune response and on the formation of the egg-induced liver granuloma during murine schistosomiasis. We find that CD1d knockout mice have a reduced Th2 response after egg laying and develop a less marked fibrotic pathology compared with wild-type mice. Altogether, our results suggest that Ag presentation of parasite glycoconjugates to CD1d-restricted T cells may be important in the early events leading to the induction of Th2 responses and to egg-induced pathology during murine schistosomiasis.

Animals↗
PubMed1986

Regional heterogeneity of glycoconjugate distribution in the glomerulus revealed by lectin-gold cytochemistry and SDS-PAGE.

The authors have used SDS-PAGE and lectin overlay analysis in parallel with lectin-gold cytochemistry to identify Helix pomatia lectin (HPL) binding glycoconjugates in rat kidney glomeruli. Previous work revealed HPL binding sites only beneath podocyte foot process bases, where they contact the glomerular basement membrane. It is shown here that after neuraminidase digestion of thin sections of glomeruli before incubation with HPL-gold complexes, the number of HPL binding sites is markedly increased. These new sites are mainly associated with the podocyte free surface (adjacent to the urinary space) and with capillary endothelial cells. By lectin overlays, this neuraminidase-dependent HPL binding was shown to be due to reaction of the lectin with desialylated podocalyxin. In contrast, HPL binding sites detected prior to neuraminidase digestion are associated with a novel glycoconjugate having a lower electrophoretic mobility than podocalyxin. Although any role for this glycoconjugate is at present speculative, it is strategically positioned at the site of interaction between foot process bases and the glomerular basement membrane. Its presence correlates with normal podocyte architecture, as shown by our previous studies on developmental and aminonucleoside nephrosis-associated changes in HPL binding to podocytes.

Animals↗
PubMed1989

Antistasin, an inhibitor of coagulation and metastasis, binds to sulfatide (Gal(3-SO4) beta 1-1Cer) and has a sequence homology with other proteins that bind sulfated glycoconjugates.

Antistasin, a 15-kDa salivary protein from the Mexican leech Haementeria officinalis, inhibits both blood coagulation and the metastasis of tumors (Tuszynski, G. P., Gasic, T. B., and Gasic, G. J. (1987) J. Biol. Chem. 262, 9718-9723). Antistasin binds to heparin-agarose, suggesting the protein interacts with sulfated glycoconjugates. The specificity of the interaction between antistasin and heparin was tested by measuring the binding of antistasin to various lipids and by comparing the ability of several charged glycoconjugates to inhibit binding. Of the lipids tested, antistasin binds with high affinity only to sulfatide (Gal(3-SO4)beta 1-1Cer) and does not bind to comparable levels of phospholipids, neutral glycosphingolipids, gangliosides, or cholesterol-3-SO4. The binding of antistasin to sulfatide is inhibited by dextran sulfate, fucoidan, and heparin, with I50 values of 1.5, 9.2, and 16 micrograms/ml, respectively. Comparable levels of chondroitin sulfates A, B, C, keratan sulfate, or hyaluronic acid do not inhibit binding. Comparisons of the amino acid sequences of antistasin and other sulfatide or heparin-binding proteins revealed a region of homology, based around the sequence Cys-Ser-Val-Thr-Cys-Gly-X-Gly-X-X-X-Arg-X-Arg, which may be a sulfated glycoconjugate binding domain. In addition, homologies were found with the alternate complement pathway protein properdin and coat proteins from malaria circumsporozoites and Herpes simplex I.

Amino Acid Sequence↗
PubMed1987

Application of backscattered electron imaging and lectin-gold cytochemistry to visualize the distribution of glycoconjugates in a basal lamina.

Basement membranes generally appear in transmission electron microscopy as thin, cross-sectioned profiles. Face-views are difficult to obtain particularly when their contours are curved or undulated. Such preparations are suited for the study of the distribution of basement membrane constituents through thickness but are limited for examining their spatial distribution. Scanning electron microscopy offers the potential of visualizing surface views. We have applied this approach to examining the three-dimensional distribution of glycoconjugates in a basement membrane. Large, face-views of the basal lamina related to maturation ameloblasts in the region where enamel of the rat incisor is EDTA soluble were exposed. Glycoconjugates were then revealed by incubating the segments in lectin-gold complexes and binding sites were visualized by backscattered electron imaging. This basal lamina was found to contain fucose, mannose and to be extremely rich in N-acetyl-D-galactosamine. The abundance of glycoconjugates containing the latter sugar residue may impart on this basal lamina selective properties which could regulate the movement of material into, and out of, the enamel layer.

Ameloblasts↗
PubMed1987

Light and electron microscopy investigation of glycoconjugates of rat hippocampus by lectin-gold technique.

The distribution of glycoconjugates in rat hippocampus was investigated by light and electron microscopy using gold-labelled lectins with different sugar specificities: ConA, WGA, PNA and LTA. A morphological correlation with cytochemical data was performed, and revealed the presence of intensely-stained (dark), unstained (light) and weakly-stained (intermediate) neurons both in Ammon's horn and in the dentate gyrus. The glycoconjugates are located in the nucleus, the perikaryal cytoplasm and the cytoskeleton of axons and dendrites: they are probably involved in the mechanisms of transport towards the synaptic membrane. The presence or absence of glycoconjugates corresponds to the particular ultrastructural aspect of the cell. This suggests the existence of different functional states of the neurons, probably correlated with the synthesis of neurotransmitter precursors or receptors.

Animals↗
PubMed1986

Differences in lectin reactivities of cellular glycoconjugates between primary human colorectal carcinomas and their metastases.

Recent studies have demonstrated that colonic carcinomas consist of heterogeneous populations of cells endowed with different abilities to metastasize. Increasing evidence suggests that cell surface carbohydrates may play an important role in cancer invasion and metastasis. Therefore the binding of five fluorescein isothiocyanate-conjugated lectins to cellular glycoconjugates was analyzed immunohistochemically in paraffin-embedded tissue sections obtained from 16 colorectal carcinomas and their 25 metastases. In positive cases peanut agglutinin (galactose beta 1----3N-acetylgalactosamine), Ulex europeus' agglutinin 1 (alpha-L-fucose), Griffonia simplicifolia agglutinin 1 (galactose), Vicia villosa agglutinin (N-acetylgalactosamine), and G. simplicifolia agglutinin 2 (N-acetylglucosamine) stained apical cell membranes in carcinomatous glands and intraluminal secretions. Nine of 16 primary colorectal carcinomas showed intratumoral heterogeneous cell populations with regard to the lectin binding which resulted in areas of fluorescence-positive and fluorescence-negative carcinomatous glands. Only one liver metastasis showed this intralesional heterogeneity in lectin binding. Nineteen of 25 metastatic tumors produced cellular glycoconjugates which differed in their lectin binding profiles from those made by the majority of the cells in the respective primary colorectal carcinomas. The findings of the present work suggest that many primary colorectal carcinomas consist of phenotypically distinct subpopulations of carcinomatous cells. Most metastatic tumors appeared to result from a selective emergence of carcinoma cells producing glycoconjugates which differed in their lectin-binding profiles from those in their respective primary colorectal carcinomas.

Carcinoma↗
PubMed1987

Comparison of the urinary glycoconjugates excreted by patients with type I and type II fucosidosis.

Glycoconjugates were isolated, by repeated chromatography on Biogel P-4, from urine of two patients with different phenotypes of fucosidosis, type I (acute) and type II (chronic). Studies of the isolated compounds with thin-layer chromatography, chromatography on Biogel P-4, gas-liquid chromatography, and 1H- and 13C-nuclear magnetic resonance spectroscopy showed differences in the excretion patterns of fucosyl glycoconjugates in the urine of these patients. The amount of the diglycosylasparagine, fuc alpha 1-6glcNAc-Asn, excreted was significantly lower for the type I than for the type II patient. On the other hand, the reducing hexasaccharide gal beta 1-4(fuc alpha 1-3)glcNAc beta 1-2man alpha 1-3/6man beta 1-4glcNAc was present in much greater quantities in urine from the type I patient. The differences in the excretion patterns of these glycoconjugates may be attributed to different substrate specificities for the residual alpha-L-fucosidases in the two forms of the disease. I propose that such differences may be exploited for the early laboratory diagnosis of the type II form of the disease, particularly by thin-layer chromatography.

Acetylglucosamine↗
PubMed1984

The role of the glycoconjugates in the migration of anuran amphibian germ cells.

The presence of a large amount of glycoconjugates on the anuran amphibian germ cells was demonstrated using fluorescein isothiocyanate lectins binding specifically to D-galactose and at a lower level, by other lectins binding specifically to N-acetyl-galactosamine. Glycoconjugates including D-galactose were found near the pseudopodial expansions and in the extracellular space, between germ cells and follicular cells. They were also disseminated in the cytoplasm. The injection of PNA lectin (from Arachis hypogea) into the endoderm inhibited the migration of 90% of the germ cells. This inhibition was lectin-concentration dependent. Ultrastructural study of germ cells, the migration of which was inhibited, showed that they were degenerating. These results suggest that glycoconjugates are related to the migratory activity of germ cells.

Acetylgalactosamine↗
PubMed1984

Modulation by retinoic acid of cellular, surface-exposed, and secreted glycoconjugates in cultured human sarcoma cells.

The effect of beta-all-trans-retinoic acid (RA) on the synthesis of cellular, cell surface, and secreted glycoconjugates by human Hs705 chondrosarcoma and Hs791 osteosarcoma cells was investigated in vitro. Untreated and RA-treated cells were labeled either metabolically with radioactive precursors or by oxidation of externally exposed cell membrane glycoprotein(s) (GP) by treatment with NalO4 or neuraminidase and galactose oxidase followed by reduction with NaB[3H]4. The cells were solubilized and analyzed by polyacrylamide gel electrophoresis followed by fluorography. RA enhanced the labeling of sialic acid and galactose residues on the GP of relative molecular weight(s) (Mr) in the range 95,000-300,000 on the surfaces of both cell types. [3H]glycosamine incorporation into GP with Mr of 100,000, 150,000, and 190,000 in both cell lines was also stimulated. In the Hs705 cells there was also an increase in the labeling of a 290,000-Mr GP. In contrast, [3H]glucosamine incorporation into glycoconjugates greater than 400,000 Mr in both the cells and the conditioned medium of Hs705 cells decreased. The latter glycoconjugates were susceptible to hyaluronidase and chondroitinases. [3H]glucosamine incorporation into a secreted 230,000-Mr GP, identified as fibronectin, was also reduced. Analyses of conditioned media of cells labeled with [35S]methionine or [14C]proline demonstrated that RA decreased the secretion of procollagen chains and fibronectin. Immunofluorescence revealed that RA alters the distribution of cell-associated fibronectin. These results demonstrated that RA increases the glycosylation of specific cellular and cell surface GP and decreases the production of secreted GP and glycosaminoglycans by the sarcoma cells.

Cell Line↗
PubMed1980

Increased biosynthesis of specific glycoconjugates in rat corneal epithelium following treatment with vitamin A.

The biosynthesis of corneal epithelial proteins and glycoconjugates and their response to vitamin A were measured in vitamin A-deficient and normal rats. The synthesis of specific high-molecular-weight epithelial glycoconjugates was directly related to the levels of vitamin A administered. Protein synthesis, however, remained unaltered. Since vitamin A is known to reverse the keratinization process, the vitamin A-regulated high-molecular-weight glycoconjugates may play a role in modulating the expression of the keratinizing phenotype.

Animals↗
PubMed1991

Usefulness of serum glycoconjugates in precancerous and cancerous diseases of the oral cavity.

Sera from 47 healthy controls, 18 normal individuals with the habit of tobacco chewing, 43 patients with oral precancerous (PC) conditions, and 40 patients with oral cancer (OC) were studied for the levels of total sialic acid (TSA), lipid-bound sialic acid (LSA), mucoid proteins, and protein-bound hexoses (PBH) (galactose and mannose). The changes in the glycoconjugate levels were insignificant between the controls and the normal tobacco chewers. All four parameters were significantly elevated in oral PC patients compared with controls. The levels of PBH and LSA showed significant increase in the oral PC patients compared with the normal tobacco chewers. A significant increase was observed in the levels of TSA, LSA, mucoid proteins, and PBH in OC patients compared with controls, normal tobacco chewers, and patients with oral PC. Increasing levels of all the biomarkers were found with progression of the malignant disease. Elevations in the levels of TSA and LSA were statistically significant in Stage IV patients compared with Stage III patients. The patients with metastases had higher levels of the biomarkers than the patients with primary OC. However, elevations only in LSA levels were statistically significant. These results suggest that evaluations of the serum glycoconjugate levels may be useful in diagnosis of the patients with oral PC or OC. In addition to their value in early detection, they can also help in staging of the disease.

Biomarkers↗
PubMedDate not supplied

Topographical and planar distribution of Helix pomatia lectin-binding glycoconjugates in secretory granules and plasma membrane of pancreatic exocrine acinar cells of the rat: demonstration of membrane heterogeneity.

The lectin-gold technique was used to detect Helix pomatia lectin (HPL) binding sites directly on thin sections of rat pancreas embedded in Lowicryl K4M and on freeze-fractured preparations of rat pancreas submitted to fracture label. On thin sections of acinar cells, whereas the content of zymogen granules was negative or weakly labeled, the limiting membrane displayed a high degree of labeling. In the Golgi complex, labeling by HPL was localized on the trans saccules and the limiting membrane of the condensing vacuoles. The latter appeared to be more intensely labeled than the membrane of the zymogen granules. Intense labeling by HPL was also observed along the microvilli and the plasma membrane. In contrast to the weak labeling of the zymogen-granule content, labeling of the acinar lumen was intense. Fracture-label preparations revealed preferential partition of HPL-binding sites to the exoplasmic half of the zymogen-granule and plasma membranes. The population of zymogen granules was, however, heterogeneous with respect to labeling intensity; the exoplasmic fracture-face of the plasma membrane was intensely and uniformly labeled, while the protoplasmic membrane halves were only weakly labeled. These observations were further confirmed and extended by the thin-section fracture-label approach. In addition, favorable profiles of thin sections of freeze-fractured zymogen granules showed that the labeling was not associated with the external surface of the limiting membrane, but rather localized over the exoplasmic fracture-face. We conclude that 1) zymogen granules contain little HPL-binding glycoconjugates, 2) HPL-binding sites are preferentially associated with the exoplasmic half of the zymogen-granule and plasma membranes, and 3) the limiting membrane of the immature condensing vacuoles carries a greater number of HPL-binding sites than that of the mature zymogen granules. These last, in turn, constitute a heterogenous population with respect to labeling density. These results support the current view that glycoconjugates are directed toward the lumen in secretory granules but become external to the cell surface after fusion of the secretory-granule membrane with the plasma membrane. Also, the results reflect membrane modifications during the maturation process of secretory granules in the exocrine pancreas in which glycoproteins are removed from the limiting membrane of the granule to become soluble and secreted with the content.

Animals↗
PubMed1989

Glycoconjugates in normal wound tissue matrices during the initiation phase of limb regeneration in adult Ambystoma.

The present study identifies, localizes, and reports the relative composition of specific glycosaminoglycans within tissue matrices during the initiation phase of limb regeneration. The regenerate tissues were harvested and assayed morphologically, histochemically, and chemically. We observed 1) a population of cells interspersed among the cells of the dermis, epimysium, perimysium, perichondrium, and periosteum. 2) This population was distinguishable by a unique pattern of glycoconjugate staining, i.e., intracellular and pericellular heparan sulfate and glycoproteins and extracellularly associated hyaluronate and glycoproteins. 3) Cells with these staining characteristics aggregated to a position directly beneath the apical epidermal cap. 4) Extracellular hyaluronate and glycoproteins colocalized with undifferentiated tissues. And 5) extracellular chondroitin sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans colocalized with differentiated tissues. The correlations of distinct glycoconjugate compositions with specific regeneration morphologies suggest the possibility that these components may be related to the phenotypic expression of tissues during regeneration.

Ambystoma↗
PubMed1995

Expression of blood group-related glycoconjugates in the junctional and other oral epithelia of rodents.

BACKGROUND: The junctional epithelium (JE) attaches the gingiva to the non-vital tooth surface and has other unusual properties which protect the underlying periodontal tissues. The JE differs from other gingival and oral epithelia in its unusual expression of cytokeratins typical of both stratifying and of simple epithelia, a phenotypic pattern possibly related to its specialized functions. METHODS: The patterns of differentiation of rodent gingival and other epithelia were examined using monoclonal antibodies against various glycoconjugates which are expressed on epithelial cell surfaces and provide an alternative marker system for regionally-differing patterns of cell maturation. RESULTS: Markers that are typical of basal cells in other stratifying epithelia were expressed by all cell strata of JE. JE lacked differentiation markers typical of other stratifying oral epithelial but showed suprabasal expression of markers typically expressed by simple epithelia and specialized epithelia, such as taste buds. CONCLUSIONS: The phenotype of rodent JE differs from that of other oral epithelia and the pattern of differentiation assessed by its expression of glycoconjugates parallels that for other phenotypic markers, such as cytokeratins. Differentiation of rodent JE is similar to that of human JE. The functional significance of these patterns of expression is not yet clear but the markers characterizing this unusual epithelium in rodents may be associated with its behavior in periodontal disease and of value to experimental studies of its development.

ABO Blood-Group System↗
PubMed1995

Glycoconjugate expression in the chick embryonic chorioallantoic membrane: comparisons of the chorionic ectoderm and allantoic endoderm.

BACKGROUND: The chorioallantoic membrane (CAM) of the chick embryo expands during embryogenesis to meet the increased oxygen demands during growth and differentiation. Temporal and spatial glycosylation patterns of CAM ectodermal and endodermal proteins likely contribute to differentiation of the functional attributes of the CAM. METHODS: Using lectins for light and electron microscopic observations, we studied the patterns of glycoconjugate expression on the ectoderm and endoderm of the chorioallantoic membrane (CAM) of the chick at days 4.5, 5.0, 5.5, 6.0, and 10 of morphogenesis. For light microscopy, samples of unfixed CAM were incubated with the following FITC lectins: Con A, DBA, GSA-I, GSA-II, PNA, SBA, UEA-I, and WGA. RESULTS: All lectins, except GSA-I and -II, gave positive results. The positive lectins, labeled with HRP, served to ultrastructurally localize PNA, SBA, and WGA, but not DBA binding to the luminal surface of the endoderm. UEA-I and Con A bound similarly except on day 10 when UEA-I no longer bound. On the ectodermal surface, only WGA bound at all times studied. PNA and SBA binding were present from days 5.0 to 6.0 but absent at days 4.5 and 10. DBA binding occurred through day 5.0 but was absent thereafter. UEA-I bound to the ectoderm at days 4.5, 5.0, and 10 but not days 5.5 and 6.0. Con A bound only on days 5.0 and 10. CONCLUSION: That the ultrastructurally similar ectoderm and endoderm of the CAM display functional differences conforms to the hypothesis that differential expression of glycoconjugate microdomains likely contributes to such functional specialization.

Allantois↗