The glycoprotein content of meconium

The clinical relevance of fetal MRI in the diagnosis of Type IV cystic sacrococcygeal teratoma--a review

The introduction of fetal magnetic resonance imaging (MRI) has improved the prenatal evaluation of uterine, placental and fetal anatomy. However, its utilization has mostly been restricted to fetal central nervous system anomalies. We review how adjunct fetal MRI was performed and diagnosis of cystic type IV sacrococcygeal teratoma was made. We also discuss the clinical relevance of fetal MRI in differentiating this lesion from other selected abdominal/pelvic cystic malformations and lesions.

Carcinoembryonic antigen in amniotic fluid

Carcinoembryonic antigen (CEA), a substance which is known to occur in high amounts in the fetal gut and also in certain tumors of the gastrointestinal tract, has been demonstrated in amniotic fluids from different stages of pregnancy. Radioimmunoassays of CEA in amniotic fluids of 91 normal pregnancies showed a decrease from a mean of 53 ng/ml at 19 weeks to 25 ng/ml at the end of gestation. The CEA activity in amniotic fluid was eluted in the same volume as a standard 125I-CEA on a Sephadex G200 column. Amniotic fluid therefore contains CEA similar in molecular weight to the CEA purified from liver metastases of colonic cancer. Among 17 cases of abnormal pregnancies, CEA elevations were observed in five with anomalous fetuses.

Glycan microheterogeneity of alpha 1-antitrypsin in serum and meconium from normal and cystic fibrosis patients by crossed immunoaffinoelectrophoresis with different lectins (Con A, LCA, WGA)

In order to test whether abnormalities of glycosylation occur in cystic fibrosis (CF), the glycan microheterogeneity of alpha 1-antitrypsin (alpha 1-AT) was studied in serum and meconium from normal individuals and patients with cystic fibrosis, by crossed immunoaffinoelectrophoresis (CIAE) using free Concanavalin A (Con A), Lens culinaris lectin (LCA) and wheat germ agglutinin (WGA). Three main results emerged from this study: (1) modification of glycosylation in serum alpha 1-AT from patients with cystic fibrosis were only significant with free Con A and WGA; this probably results from a reduced synthesis of the bi-antennary side-chains or by their increased catabolism. (2) Differences in isoforms found in alpha 1-AT from normal individuals and patients with CF using free Con A, LCA, were more pronounced in the meconium than in the serum; this may provide a useful test in diagnosis of cystic fibrosis. (3) There was parallelism between the behaviour of alpha 1-AT in serum and meconium from patients with CF using LCA, Con A; this may be explained by different types or levels of disfunction affecting a glycosylation mechanism.

Concanavalin A binding sites in fetal, adult, transitional, and malignant rectosigmoid mucosa

We studied mucin histochemistry in 25 rectosigmoid adenocarcinomas and in the transitional mucosa adjacent to these tumors using standard techniques for the detection of neutral and acid sialomucins and sulfomucins and the paradoxical concanavalin A (Con A) stain. This histochemical procedure selectively detects residues of mannose in glycoproteins exposed to brief steps of oxidation and reduction. Those techniques were also used to study histologically normal mucosa of specimens with carcinoma, normal rectosigmoid mucosa of patients without inflammatory or neoplastic bowel disease, hyperplastic rectal polyps, and rectosigmoid mucosa of human fetuses. Normal mucosa and hyperplastic polyps mainly contained sulfomucins and did not display Con A binding activity with any of the variants of the stain. In contrast, fetal, transitional, and malignant mucosa predominantly showed sialomucins and although not reactive with the standard Con A sequence, displayed binding activity for the lectin after short oxidative-reductive steps. These results provide further evidence that transitional and malignant mucosa produce markedly abnormal mucins whose histochemical patterns represent a re-emergence of the fetal type found during development. The principles of the paradoxic Con A reaction may be applied to unmask lectin binding activity in apparently unreactive sites.

Studies of the limited degradation of mucus glycoproteins. The effect of dilute hydrogen peroxide

1. The action of dilute H2O2 on a series of ovarian-cyst glycoproteins and glycopolypeptides was investigated. 2. Both native glycoproteins and the glycopolypeptides were carbohydrate-rich, of relatively low molecular weight and of simple structure. 3. At pH 5.6 and 37 degrees C, exposure to H2O2 for a limited time brought about a partial degradation, the molecular weight being decreased by 2-4-fold. 4. Carbohydrate analysis showed very little change in the oligosaccharide moiety, apart from a small decrease in sialic acid in some samples. 5. Amino acid analysis showed minor changes in serine, threonine and proline contents, but almost total loss of histidine. Concomitantly, there was a small gain in aspartic acid. 6. Myosin, examined at both pH 5.7 and 6.7, exhibited generally similar behaviour, there being losses of other amino acid residues as well as histidine: the viscosity was decreased to a low value, and a range of peptides of widely varying size was produced. 7. It is suggested that attack on the histidine residue, with partial conversion into aspartic acid, is accompanied by scission of the histidyl peptide bond.

Carbohydrate patterns of endoscopic mucosal biopsies in cancer of the stomach and chronic gastritis

The monosaccharide composition of the soluble glycoproteins of endoscopic gastric biopsies was studied with gas-liquid chromatography in patients with carcinoma of the stomach and in patients with chronic gastritis (controls). The analyses showed (1) that monosaccharide patterns were similar in the antrum and corpus of patients with chronic gastritis, (2) that the mannose content relative to the galactose content was increased in the tumor as compared with the antrum of the same stomach (p less than 0.05) and with the antrum (p less than 0.05) and corpus (p less than 0.02) of the control stomachs, and (3) that the N-acetylgalactosamine and N-acetylglucosamine content tended to be decreased in the tumor area as compared with the antrum and corpus of control stomachs. The changes in the histologically tumor-free part of the corpus of the cancer stomachs tended to be similar in direction to those in the tumor itself.

Structures of fifteen oligosaccharides isolated from new-born meconium

New born meconium contains at least a hundred oligosaccharides. In this study the isolation and characterization of the major constituents is described. The structure elucidation of 15 neutral and acidic oligosaccharides was carried out by methylation analysis, mass spectrometry and 360-MHz 1H-NMR spectroscopy. The results show that the oligosaccharides accumulating in human meconium are probably products of the catabolism of the O- and N-linked carbohydrate chains of glycoproteins. It is proposed that endo-N-acetyl-alpha-D-galactosaminidase, endo-beta-D-galactosidase and endo-N-acetyl-beta-D-glucosaminidase are involved in the production of these compounds.

Carbohydrate content of endoscopic gastric biopsies in carcinoma of the stomach

An investigation of the glycoproteins of gastric mucus from biopsies of patients with gastric cancer has shown a change in certain carbohydrate components. There is a significant increase (P less than 0-001) in mannose and a significant decrease in N-acetylgalactosamine in both secretors and non-secretors from cancer-free and cancer-bearing regions of the stomach as compared with normal stomachs. The possible reasons for this change and its relation to two possible glycoprotein fractions are discussed.