Biomedical subjects

E Maes

Publications and source records attributed to E Maes.

At least 19 recordsLinked to original sources

PubMed2001

Sd(a)-antigen-like structures carried on core 3 are prominent features of glycans from the mucin of normal human descending colon.

This paper describes structural characterization by NMR, MS and degradative studies of mucin glycans from normal human descending colon obtained freshly at autopsy. The saccharides were mainly based on core 3 (GlcNAcbeta1-3GalNAc). Among the terminal saccharide determinants Sd(a)/Cad-antigen-like structures were prominent, and Lewis x, sialyl Lewis x and sulphated Lewis x were found as minor components, whereas blood group H and A antigenic determinants were absent. The saccharides were markedly different from those of mucins from colon cancers or colon cancer cell lines analysed so far, in which cores 1 and 2 are prominent features, and in which various other terminal determinants have been found, but not Sd(a)/Cad.

Autopsy↗

PubMed2001

The nematode Caenorhabditis elegans synthesizes unusual O-linked glycans: identification of glucose-substituted mucin-type O-glycans and short chondroitin-like oligosaccharides.

The free-living nematode Caenorhabditis elegans is a relevant model for studies on the role of glycoconjugates during development of multicellular organisms. Several genes coding for glycosyltransferases involved in the synthesis of N- and O-linked glycans have already been isolated, but, apart from repetitive dimers of glycosaminoglycans, no detailed structure of either type of component has been published so far. This study aimed to establish the structures of the major O-glycans synthesized by C. elegans to give an insight into the endogenous glycosyltransferase activities expressed in this organism. By the use of NMR and MS, we have resolved the sequence of seven of these components that present very unusual features. Most of them were characterized by the type-1 core substituted on Gal and/or GalNAc by (beta1-4)Glc and (beta1-6)Glc residues. Another compound exhibited the GalNAc(beta1-4)N-acetylglucosaminitol sequence in the terminal position, to which was attached a tetramer of beta-Gal substituted by both Fuc and 2-O-methyl-fucose residues. Our experimental procedure led also to the isolation of glycosaminoglycan-like components and oligomannosyl-type N-glycans. In particular, the data confirmed that C. elegans synthesizes the ubiquitous linker sequence GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl.

Animals↗

PubMed2000

O-glycan variability of egg-jelly mucins from Xenopus laevis: characterization of four phenotypes that differ by the terminal glycosylation of their mucins.

Eggs from Xenopus laevis are surrounded by several layers of jelly that are needed for proper fertilization. Jelly coat is composed of high-molecular-mass glycoconjugates to which are bound many globular proteins. O-glycans released from the jelly coat of X. laevis have been partially described in previous studies. In this study, we compared the glycosylation pattern of the egg jelly coat isolated from six specimens of X. laevis. The O-glycans were released from jelly coats by alkali/borohydride treatment. Structural characterization was performed through a combination of one- and two-dimensional (1)H-NMR and methylation analysis. This allowed the description of a new family of sulphated O-glycans present in jelly coats of all X. laevis. However, the jelly O-glycans showed a low extent of polymorphism between specimens. This intra-specific variability was restricted to the terminal substitution of O-linked oligosaccharides. The differential expression of two glycosyltransferase [an alpha-(1-->4) galactosyltransferase and an alpha-(1-->3) fucosyltransferase] activities resulted in the characterization of four phenotypes of X. laevis. Furthermore, electrophoretic analysis suggested that the high-molecular-mass fraction of jelly coat was mostly composed of mucin-type glycoproteins. Blot analysis with lectins confirmed that the glycan variability was borne by these mucin-type components. However, fertilization assays suggested that the glycan polymorphism had no repercussion on egg fertilizability.

Animals↗

PubMed2000

Recombinant human interleukins IL-1alpha, IL-1beta, IL-4, IL-6, and IL-7 show different and specific calcium-independent carbohydrate-binding properties.

A method was developed for the determination of putative lectin activities of cytokines. It involved the immunoblotting measurement of the quantity of these cytokines unbound to a series of different immobilized glycoconjugates and displacement of the bound cytokines with oligosaccharides of known structures. This method allows demonstrating that the following interleukins specifically recognize different oligosaccharide structures in a calcium-independent mechanism: interleukin-1alpha binds to the biantennary disialylated N-glycan completed with two Neu5Acalpha2-3 residues; interleukin-1beta to a GM4 sialylated glycolipid Neu5Acalpha2-3Galbeta1-Cer having very long and unusual long-chain bases; interleukin-4 to the 1,7 intramolecular lactone of N-acetyl-neuraminic acid; interleukin-6 to compounds having N-linked and O-linked HNK-1-like epitopes; and interleukin-7 to the sialyl-Tn antigen. Because the glycan ligands are rare structures in human circulating cells, it is suggested that such activities could be essential for providing specific signaling systems to cells having both the receptors and the oligosaccharide ligands of the interleukin at their cell surface.

Animals↗

PubMed2000

Massive in vitro synthesis of tagged oligosaccharides in 1-benzyl-2-acetamido-2-deoxy-alpha-D-galactopyranoside treated HT-29 cells.

Permanent exposure of differentiated HT-29 cells to the sugar analogue, 1-benzyl-2-acetamido-2-deoxy-alpha-D-galactopyranoside (GalNAcalpha- O -bn) leads to marked effects upon the phenotypic properties of mucin-secreting or enterocyte-like HT-29 cells: an inhibition in the secretion of mucins, a blockade in the apical targeting of membrane brush border glycoproteins and a swelling of cells with intracellular accumulation of numerous vesicles. Folch extraction and partition of treated enterocyte-like HT-29 cells revealed a very important accumulation of orcinol and/or resorcinol reactive material in the upper phase (usually containing gangliosides), as compared with untreated HT-29 cells and with treated and untreated Caco-2 cells. Structural analysis indicated the accumulation of a series of GalNAcalpha- O -bn derived oligosaccharides, most of them with the common core Galbeta1-3GalNAcalpha- O -bn. These oligosaccharides contained residues of GlcNAc, Gal, Neu5Ac, or Fuc. In particular, the tagged sialyl-Lewis(x)was identified, as well as more complex sialylated derivatives, including the sialyl-Lewis(x)substituted by an additional Neu5Ac residue. The benzylated oligosaccharides were not significantly detected in the culture medium except for Galbeta1-3GalNAcalpha- O -bn. Upon reversion of the treatment, these derivatives dis-appeared from the cells within few days, however were not recovered as such in the culture medium. Intracellular degradation occurred with desialylation and defucosylation as the first steps. The spectacular accumulation of benzylated oligosaccharides in HT-29 cell, permanently exposed to GalNAcalpha- O -bn very likely plays an important role in the alterations of cellular processes previously described in this cell line. The HT-29 cell culture system also appears to be an efficient source of several tagged oligosaccharides.

Cell Differentiation↗

PubMed1999

Epidemiology, etiology, and impact of traveler's diarrhea in Jamaica.

CONTEXT: Traveler's diarrhea (TD) can incapacitate travelers. Characteristics of TD could be helpful in identifying individuals who might benefit from a vaccine against TD. OBJECTIVE: To determine epidemiology, etiology, and impact of TD in Jamaica. Design Two-armed, cross-sectional survey conducted between March 1996 and May 1997. SETTING: Sangster International Airport and 10 hotels in Montego Bay area, Jamaica. SUBJECTS: To investigate epidemiology and impact, 30369 short-term visitors completed a questionnaire just before boarding their homebound aircrafts. To investigate etiology, 322 patients (hotel guests) with TD provided stool samples. MAIN OUTCOME MEASURES: Attack and incidence rates of reported diarrhea and of classically defined TD (> or =3 unformed stool samples in 24 hours and > or =1 accompanying symptom), incapacity, risk factors, and etiology. RESULTS: The attack rate for diarrhea was 23.6% overall, with 11.7% having classically defined TD. For a mean duration of stay of 4 to 7 days, the incidence rate was 20.9% (all TD) and 10.0% (classic TD). Among airport respondents, the incapacity lasted a mean of 11.6 hours. Less than 3% of all travelers avoided potentially high-risk food and beverages. The most frequently detected pathogens were enterotoxigenic Escherichia coli, Rotavirus, and Salmonella species. CONCLUSIONS: A realistic plan for reducing TD is needed. Preventive measures such as the improvement of hygienic conditions at the destination, and/or the development of vaccines against the most frequent pathogens associated with TD may contribute toward achieving this goal.

Adolescent↗

PubMed1999

Quantitative cleavage of the N-glycosidic bond under the normal conditions of methanolysis used for the analysis of glycoprotein monosaccharides.

The most common method used for the liberation of monosaccharides from glycoprotein N-glycans involves anhydrous methanolysis because it liberates almost quantitatively monosaccharides as O-methylglycosides, which are resistant to further degradation. However, it is generally assumed that this method does not cleave quantitatively the N-glycosidic bonds. This paper demonstrates that classical methanolysis conditions quantitatively cleave the N-glycosidic bond (96%), liberating glucosamine (and not its O-methylglycosides) and other minor reaction products which were identified. Because other N-acetyl-d-glucosamine (GlcNAc) residues are quantitatively liberated as the O-methylglycosides of glucosamine, the GlcNAc residue involved in the N-glycosidic bond is separated from the others using gas chromatography of heptafluorobutyrate derivatives.

Chromatography, Gas↗

PubMed1999

Structural analysis of 20 oligosaccharide-alditols released from the jelly coat of Rana palustris eggs by reductive beta-elimination characterization of the polymerized sequence [Gal(beta1, 3)GalNAc(alpha1-4)]n.

The eggs of amphibians are surrounded by three to eight layers of jelly coats. This extracellular matrix is mainly composed of hydrated mucin-type glycoproteins. These highly glycosylated molecules are synthesized by oviduct and play an important role in the fertilization process. Recent structural analyses have shown the strict species-specificity of the O-linked oligosaccharides which constitute 60-70% of these oviducal mucins. Consequently, these carbohydrate chains represent new phenotypic markers, and from a biological point of view, can influence parasite tropism or can be involved in species-specific interaction of gametes. The primary structure of 20 oligosaccharide-alditols, released by alkali/borohydride treatment from the mucin of Rana palustris egg jelly coats, was established by 1H and 13C-NMR analysis. Thirteen of these components possess new structures and the polymerization of the sequence Gal(beta1-3)GalNAc(alpha1-4) characterizes the species-specificity of R. palustris.

Animals↗

PubMed1999

Structural analysis of 13 neutral oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Rana temporaria.

Amphibian eggs are always surrounded by an extracellular matrix, named the jelly coat. This is mainly composed of a highly O-glycosylated, mucin-type glycoprotein. This work has consisted of isolating O-linked neutral oligosaccharides from oviducal mucin of Rana temporaria, with a view to determining their primary structure. Hence, these carbohydrate chains have been released by alkaline borohydride treatment leading to stable glycans. The oligosaccharide-alditols have been purified by ion-exchange chromatography and separated by HPLC. The primary structure of 13 of these carbohydrate chains have been obtained by 1D/2D 1H-NMR spectroscopy and methylation analyses, in combination with MALDI-TOF mass spectroscopy. The results confirm what has been observed for six other amphibians about the species-specificity of the carbohydrate moieties and their likely involvement in the species-specific gamete recognition.

Animals↗

PubMed1999

Acquisition of species-specific O-linked carbohydrate chains from oviducal mucins in Rana arvalis. A case study.

The extracellular matrix surrounding amphibian eggs is composed of mucin-type glycoproteins, highly O-glycosylated and plays an important role in the fertilization process. Oligosaccharide-alditols were released from the oviducal mucins of the anuran Rana arvalis by alkali-borohydride treatment in reduced conditions. Neutral and acidic oligosaccharides were fractionated by ion-exchange chromatographies and purified by HPLC. Each compound was identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) spectrometry, NMR spectroscopy, electrospray ionization-tandem mass spectroscopy (ESI-MS/MS) and permethylation analyses. This paper reports on the structures of 19 oligosaccharide-alditols, 12 of which have novel structures. These structures range in size from disaccharide to octasaccharide. Some of them are acidic, containing either a glucuronic acid or, more frequently, a sulfate group, located either at the 6 position of GlcNAc or the 3 or 4 positions of Gal. This latter sulfation is novel and has only been characterized in the species R. arvalis. This structural analysis led to the establishment of several novel carbohydrate structures, demonstrating the structural diversity and species-specificity of amphibian glycoconjugates.

Animals↗

PubMed1999

Immunization performance measurement in a changing immunization environment.

OBJECTIVE: The measurement of performance in the delivery of recommended vaccinations for children is used frequently as a marker for quality of care and as an outcome for studies of interventions to improve immunization coverage levels. The critical element of immunization performance measurement is the determination of immunization status. This methodologic review 1) discusses immunization status as a measure of quality of primary care for children, 2) describes immunization status measures used in immunization intervention studies, and 3) examines selected technical issues of immunization status measurement. METHODS AND TOPICS: 1) Description of the characteristics of immunization status measurements obtained by a systematic review of studies published between 1980 and 1997 on interventions to raise immunization coverage, and 2) illustration of technical considerations for immunization status measurement using one local database and one national database of immunization histories. Technical issues for immunization status measurement include 1) the need to use documented immunization histories rather than parental recall to determine immunization status, 2) the need to link records across providers to obtain complete records, 3) the sensitivity of immunization status to missing immunization data, and 4) the potential of measures incorporating combinations of immunizations to underestimate the degree of vaccination in a population. CONCLUSIONS: Immunization performance measurement has many characteristics of a robust quality of care measure, including high acceptance by primary care providers of routine vaccination, association of immunization status with the conduct of other clinical preventive services, agreed-on technical and programmatic standards of care, and legislative requirements for medical record documentation. However, it is not without challenges. Careful attention to technical issues has potential to improve immunization delivery health services research.

Child↗

PubMed1998

Measles outbreaks in Micronesia, 1991 to 1994.

BACKGROUND: Several islands in Micronesia experienced large measles outbreaks, during 1991 through 1994. Except for Guam, none of the islands had reported measles outbreaks during the previous 20 years. METHODS: To characterize the outbreaks, measles surveillance data, hospital records and death certificates were reviewed. Preoutbreak vaccination coverage rates were assessed by reviewing public health vaccination records. Viral isolates were genetically sequenced to determine the source of transmission. Linear regression analysis was performed to assess the effectiveness of outbreak control measures. RESULTS: Between 1991 and 1994 more than 1300 measles cases and 16 measles-related deaths were reported in Micronesia. Preoutbreak vaccination coverage rates among 2-year-old children were 55 to 94%. Genetic sequencing of the viral isolates and epidemiologic investigations suggested transmission between islands and new importations from outside of Micronesia. The highest attack rates were among children ages < 5 years (20/1000) and 10 to 19 years (38/1000). Compared with attack rates among children ages < 1 and 10 to 19 years, attack rates were lower among those ages 5 to 9 years, in whom 2-dose vaccination coverage rates were highest (P < 0.001). Early and rapid implementation of mass vaccination campaigns was significantly associated with shorter duration of outbreaks (P = 0.049). CONCLUSION: The measles outbreaks in Micronesia show that island populations may be highly susceptible to measles. High two-dose vaccination coverage levels must be maintained to prevent such outbreaks. Early and rapidly implemented mass measles vaccination campaigns were effective in control of island outbreaks. Strengthening public health infrastructure and surveillance is necessary for early identification of outbreaks and rapid implementation of mass campaigns.

Adolescent↗

PubMed1997

Primary structure of seven sulfated oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Rana temporaria. Characterization of the sequence HSO3 (3) GlcA (beta1--3)Gal.

The mucins isolated from Rana temporaria egg jelly coats were found to be composed of Gal, Fuc, GlcNac, GalNAc and GlcA acid. The primary structure of seven sulfated oligosaccharide-alditols was obtained by 1D/2D NMR analyses (1H-13C). The results show the presence of the sulfate monosaccharides. HSO3(3)Gal, HSO(6)GlcNAc and HSO3(3)GlcA. The sequence HSO3(3)GlcA (beta1-3)Gal, which constitutes the major determinant of the HNK-1 oncofoetal epitope, was characterized.

Animals↗

PubMed1997

Impact of measurement and feedback on vaccination coverage in public clinics, 1988-1994.

OBJECTIVE: To investigate whether a reported rise in vaccination coverage in Georgia public clinics during the period 1988 through 1994 was artifactual or real and, if real, to determine the extent to which the rise could be associated with a program of measurement and feedback. DESIGN: Examination of data from Georgia public clinics, doses-administered records, and National Health Interview Surveys. SETTING/PARTICIPANTS: Children attending Georgia public clinics. INTERVENTION: Measurement of vaccination coverage and feedback to providers. MAIN OUTCOME MEASURE: Vaccination coverage rates. RESULTS: For the period 1988 through 1994, 136 004 Georgia public clinic vaccination records for children 21 to 23 months of age were reviewed. Median series-completion rates at public clinics rose from 53% to 89%, while indexes of under-vaccination fell: missed opportunities for simultaneous vaccination (6% to 0%), lost contact for more than 12 months (14% to 1%), and first vaccination more than 1 month late (19% to 8%). According to the independent doses-administered database, the proportion of children starting the primary series very late (> or =12 months old) fell from 14% to 6%, and the series-completion index rose from 64% to 83%, suggesting that improvements could not be wholly ascribed to better clinic record keeping. In 1988, vaccination coverage of children 24 months of age in the National Health Interview Survey (NHIS) was 53%, identical to median public clinic coverage in Georgia; in 1993, NHIS coverage was 60%, while median public clinic coverage in Georgia was 90%, suggesting that the rise in coverage in Georgia public clinics exceeded national trends. Patterns within the coverage changes suggest an association with the process of measurement and feedback. CONCLUSIONS: A marked increase in vaccination coverage occurred in Georgia public clinics associated with a program of annual measurement and feedback.

Community Health Centers↗

PubMed1997

Structural analysis of the oligosaccharide-alditols released by reductive beta-elimination from oviducal mucins of Rana temporaria.

The carbohydrate chains of the mucins which constitute the jelly coat surrounding the eggs of Rana temporaria were released by alkaline borohydride treatment. Neutral and acidic oligosaccharide-alditols were purified by ion-exchange chromatography and HPLC. From the structural analysis, based upon 1H and 13C-NMR spectroscopy in combination with MALDI-TOF, the following glycan units are proposed.

Animals↗

PubMed1996

Isolation and structures of glycoprotein-derived free oligosaccharides from the unfertilized eggs of Scyliorhinus caniculus. Characterization of the sequences galactose(alpha 1-4)galactose(beta 1-3)-N-acetylglucosamine and N-acetylneuraminic acid(alpha 2-6)galactose(beta 1-3)-N-acetylglucosamine.

As previously reported [Ishii, K., Iwasaki, M., Inoue, S., Kenny, P. T. M., Komura, H. & Inoue, Y. (1989) J. Biol. Chem. 264, 1623-1630; Inoue, S., Iwasaki, M., Ishii, K., Kitajima, K. & Inoue, Y. (1989) J. Biol. Chem. 264, 18520-185261, the unfertilized eggs of two different species of fresh-water fish, Plecoglossus altivelis and Tribodolon hakonensis, contain relatively large amounts of free sialooligosaccharides. These oligosaccharides were found to derive from glycophosphoproteins, owing to the activity of a peptide - N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase [Iwasaki, M., Seko, A., Kitajima, K., Inoue, Y. & Inoue, S. (1992) J. Biol. Chem. 267, 24287-24296; Seko, A., Kitajima, K., Inoue, Y. & Inoue, S. (1991) J. Biol. Chem. 266, 22110-22114]. Here we describe a new type of free oligosaccharides, isolated from unfertilized eggs of Scyliorhinus caniculus. From the structural analysis, based upon 1H-NMR spectroscopy, the following glycan units are proposed.[Formula: see text]

Animals↗

PubMed1996

Assessment and related immunization issues in the Special Supplemental Nutrition Program for Women, Infants and Children: a status report.

This article reports the results of a survey undertaken to determine the current level of collaboration between Women, Infants and Children (WIC) programs and immunization services. While the results of this study are encouraging, WIC needs to continue to place emphasis on using written or computerized immunization records for client screening, utilize available computer hardware and software to assist assessments, and expand the use of food voucher incentives as a strategy to improve coverage.

Health Services Accessibility↗

PubMed1996

Measles vaccination levels of children enrolled in WIC during the 1991 measles epidemic in New York City.

OBJECTIVES: This study assessed measles vaccination rates and risk factors for lack of vaccination among preschool children enrolled in the Special Supplemental Food Program for Women, Infants, and Children (WIC) during the 1991 measles epidemic in New York City. METHODS: Children aged 12 to 59 months presenting for WIC certification between April 1 and September 30, 1991, at six volunteer WIC sites in New York City were surveyed. RESULTS: Of the 6181 children enrolled in the study, measles immunization status was ascertained for 6074 (98%). Overall measles coverage was 86% (95% confidence interval [CI] = +/- 1%) and at least 90% by 21 months of age (95% CI = +/- 1%). Young age of the child, use of a private provider, and Medicaid as a source of health care payment were risk factors for lack of vaccination (P < .001). CONCLUSIONS: During the peak of a measles epidemic, measles immunization rates were more than 80% by 24 months of age in a sample of WIC children. The ease of ascertaining immunization status and the size of the total WIC population underscore the importance of WIC immunization initiatives.

Child, Preschool↗