Measurement of Elastase and Cysteine Proteinases in Synovial Fluid of Patients with Rheumatoid Arthritis, Sero-Negative Spondylarthropathies, and Osteoarthritis

Synovial fluid samples were collected from 45 patients with rheumatoid arthritis, spondylarthropathy, or osteoarthritis, to study their content of elastase (EC 3.4.21.37) and of cysteine proteinases (EC 3.4.22.1, 3.4.22.15). We measured both elastase complexed with alpha 1-proteinase inhibitor and elastase activity toward the substrate L-pyroglutamyl-L-prolyl-L-valine-p-nitroanilide. Cysteine proteinase activities were measured with the substrates N-benzyloxycarbonyl-L-phenylalanyl-L-arginine-7-amido-4-methylcoumarin (Z-Phe-Arg-AMC) and Z-Arg-Arg-AMC and the inhibitor E-64 [L-trans-epoxysuccinyl-leucyl-amido-(4-guanidino)-butane]. In all these enzyme assays, higher median values were obtained in inflammatory arthropathies than in osteoarthritis. The concentration of the elastase-alpha 1-proteinase inhibitor complex and of elastase and cysteine proteinase activities were statistically higher in patients with rheumatoid arthritis than in patients with osteoarthritis. The difference in results between patients with spondylarthropathy and patients with osteoarthritis was statistically significant only for the elastase-alpha 1-proteinase inhibitor complex. The median values of the complex and of both enzyme activities were higher in patients with rheumatoid arthritis than in patients with spondylarthropathy; however, the difference was statistically significant only for the cysteine proteinase activity measured with Z-Arg-Arg-AMC substrate. These results suggest that both elastase and cysteine proteinases, which are increased in patients with inflammatory arthritis, are involved in cartilage degradation in these arthropathies.

[Breast pilomatrixoma manifested as microcalcifications on mammography: report of two cases]

Pilomatricoma is a benign tumor of hair follicule origin corresponding to a firm subcutaneous nodule requiring histology for diagnosis. Only few breast pilomatricomas have been reported, with imaging showing well defined nodules with microcalcifications. We report two cases of intra-mammary pilomatricomas presenting as ACR BI-RADS 4 and 5 microcalcifications, suspicious for malignant tumors. Percutaneous biopsy confirmed the histological diagnosis. Malignant pilomatricomas have been reported, suggesting that all pilomatricomas should be resected.

[Can US-guided vacuum-assisted biopsies be an alternative to diagnostic surgery in cases of non-diagnostic core needle biopsy?]

PURPOSE

To assess US-guided vacuum-assisted biopsies in the diagnosis of suspicious sonographic breast lesions after non-diagnostic core needle biopsies (CNB).

PATIENTS AND METHODS

Retrospective study of 42 females with suspicious breast lesions at US. CNB previously performed were non-diagnostic. Because of the larger sample size, vacuum-assisted biopsies were performed, instead of surgical biopsy.

RESULTS

Vacuum-assisted biopsies showed 32 benign lesions. Histologic examination of the CNB showed non-specific fibrous tissue in 43% of cases as opposed to 7.1% for vacuum-assisted biopsies. The latter provided a more specific diagnosis (mainly fibrocystic breast disease). From a total of 4 lesions that were suspicious at CNB, 3 were diagnosed as malignancies after vacuum-assisted biopsy and one case was a "borderline" lesion. Three additional malignant and three additional borderline lesions were diagnosed on vacuum-assisted biopsies. In 11 cases, surgical excision was performed, and all diagnoses from vacuum-assisted biopsies were confirmed at microscopy, except in one case where it was underestimated (ADH versus DCIS).

CONCLUSION

US-guided vacuum-assisted biopsy is a reliable technique. Because it provides more tissue than CNB, it can be an alternative to diagnostic surgery after non-diagnostic CNB. Indeed, it allows confirmation of the diagnosis and provides a more specific diagnosis of benign lesions. With regards to malignant and borderline lesions, it avoids the risk of false-negative CNB and overlooking carcinomas.

[Value of ultrasound detection of post-Mammotome scar for preoperative localization of breast microcalcifications]

PURPOSE

We attempted to find ultrasound scar subsequent to vacuum assisted breast biopsy (Mammotome system) previously performed, and to enhance its value for preoperative localization.

MATERIALS AND METHODS

Our study included 34 females requiring needle localization prior to surgery. They previously had Mammotome core biopsies for clustered microcalcifications. US examination was systematically performed before insertion of the metallic marker, in order to detect a scar. Identification of the scar allowed ultrasonographic guided localization. The accuracy was correlated with histologic findings.

RESULTS

Ultrasonography detected a scar in 21 of the 34 patients (63%). Among all these cases, a perfect correlation could be established between ultrasound target and histologic scar revealed by microscopic examination.

CONCLUSION

Ultrasound detection of scar allows ultrasonographic guidance and can therefore be the only alternative in cases of absence or displacement of the marker clip.

Involvement of glycosylation in the intracellular trafficking of glycoproteins in polarized epithelial cells

The surface of epithelial cells is composed of apical and basolateral domains with distinct structure and function. This polarity is maintained by specific sorting mechanisms occurring in the Trans-Golgi Network. Peptidic signals are responsible for the trafficking via clathrin-coated vesicles by means of an interaction with an adaptor complex (AP). The basolateral targeting is mediated by AP-1B, which is specifically expressed in epithelial cells. In contrast, the apical targeting is proposed to occur via apical raft carriers. It is thought that apically targeted glycoproteins contain glycan signals that would be responsible for their association with rafts and for apical targeting. However, the difficulty in terms of acting specifically on a single step of glycosylation did not allow one to identify such a specific signal. The complete inhibition of the processing of N-glycans by tunicamycin often results in an intracellular accumulation of unfolded proteins in the Golgi. Similarly, inhibition of O-glycosylation can be obtained by competitive substrates which gave a complex pattern of inhibition. Therefore, it is still unknown if glycosylation acts in an indirect manner, i.e. by modifying the folding of the protein, or in a specific manner, such as an association with specific lectins.

Endocan is a novel chondroitin sulfate/dermatan sulfate proteoglycan that promotes hepatocyte growth factor/scatter factor mitogenic activity

Proteoglycans that modulate the activities of growth factors, chemokines, and coagulation factors regulate in turn the vascular endothelium with respect to processes such as inflammation, hemostasis, and angiogenesis. Endothelial cell-specific molecule-1 is mainly expressed by endothelial cells and regulated by pro-inflammatory cytokines (Lassalle, P., Molet, S., Janin, A., Heyden, J. V., Tavernier, J., Fiers, W., Devos, R., and Tonnel, A. B. (1996) J. Biol. Chem. 271, 20458-20464). We demonstrate that this molecule is secreted as a soluble dermatan sulfate (DS) proteoglycan. This proteoglycan represents the major form either secreted by cell lines or circulating in the human bloodstream. Because this proteoglycan is specifically secreted by endothelial cells, we propose to name it endocan. The glycosaminoglycan component of endocan consists of a single DS chain covalently attached to serine 137. Endocan dose-dependently increased the hepatocyte growth factor/scatter factor (HGF/SF)-mediated proliferation of human embryonic kidney cells, whereas the nonglycanated form of endocan did not. Moreover, DS chains purified from endocan mimicked the endocan-mediated increase of cell proliferation in the presence of HGF/SF. Overall, our results demonstrate that endocan is a novel soluble dermatan sulfate proteoglycan produced by endothelial cells. Endocan regulates HGF/SF-mediated mitogenic activity and may support the function of HGF/SF not only in embryogenesis and tissue repair after injury but also in tumor progression.

Heterozygous M3Mmalton alpha1-antitrypsin deficiency associated with end-stage liver disease: case report and review

Alpha1-antitrypsin (alpha1AT) deficiency is an autosomal recessive disorder that can cause pulmonary emphysema and liver disease. We report here the case of a 59-year-old woman who was admitted to hospital for evaluation of jaundice. She had no history of hepatitis or childhood liver disease. She had never received a blood transfusion, nor had she abused drugs or alcohol. Transjugular liver biopsy was then performed and revealed a micronodular cirrhosis. Ten months later, because of persistent liver cell failure and ascites, she underwent an orthotopic liver transplantation. Investigation of alpha1AT system in the proband revealed a substantial decrease in serum alpha1AT associated with a low elastase inhibitory capacity. The Pi phenotype revealed a PiM-like profile. Sequencing of exons 1-5 demonstrated the presence of the M3 allele. Moreover, a triple nucleotide deletion was detected in exon 2 of one allele. This caused an "in-phase" frameshift, coding for a protein deficient in a single Phe residue, which corresponded to the Mmalton variant. After liver biopsy, periodic acid-Schiff-positive acidophilic bodies resistant to diastase digestion were observed in the cytoplasm of hepatocytes. These results demonstrated that our patient had a heterozygous M3Mmalton alpha1AT genotype related to a deficiency phenotype. This observation is the first of a patient with heterozygous Mmalton genotype associated with an alpha1AT deficiency that induced severe liver disease requiring orthotopic liver transplantation.

Studies of acceptor site specificities for three members of UDP-GalNAc:N-acetylgalactosaminyltransferases by using a synthetic peptide mimicking the tandem repeat of MUC5AC

The acceptor specificity of three major isoforms of UDP-GalNAc:polypeptide N-acetylgalactosaminyltranferases (murine recombinant proteins GaNTase-T1, -T2 and -T3) was investigated using the synthetic peptide (GTTPSPVPTTSTTSAP) containing clusters of threonine residues mimicking the mucin tandem repeat unit of MUC5AC. The O-glycosylated products obtained after in vitro reactions were fractionated by capillary electrophoresis and the purified glycopeptides were characterized by MALDI mass spectrometry (number of O-GalNAc residues) and by Edman degradation (site location). A maximum of three GalNAc residues was transferred into the MUC5AC motif peptide and the preferential order of incorporation for each GaNTase isoform was determined. Our results suggest that clusters of threonine appear to be essential for site recognition of peptide backbone by the ubiquitous GaNTases and also support the notion that the different GaNTase isoforms with varying substrate specificities are involved in a hierarchical order of O-glycosylation processing of the mucin-type O-glycoproteins.

Glycopeptide N-acetylgalactosaminyltransferase specificities for O-glycosylated sites on MUC5AC mucin motif peptides

The recombinant proteins of the two novel UDP-N-acetylgalactosamine (GalNAc) glycopeptide:N-acetylgalactosaminyltransferases (designated gpGaNTase-T7 and gpGaNTase-T9) were assayed with O-glycosylated products obtained from the prior action of the ubiquitous transferases (GaNTase-T1 and GaNTase-T2) towards MUC5AC mucin motif peptides (GTTPSPVPTTSTTSAP and peptides with single amino acid substitutions, GTTPSAVPTTSTTSVP and GTTPSPVPTTSITSVP, that are a reflection of mucin molecule polymorphism). gpGaNTase-T9 is known to be expressed differentially and more abundantly than gpGaNTase-T7 in some tissues; the results of in vitro glycosylation also indicates a difference in acceptor substrate specificities between the gpGaNTase isoforms. With the use of capillary electrophoresis, MS and Edman degradation, our study suggests that, in the O-glycosylation of mucin-type proteins, approach and recognition signalling by gpGaNTase-T7 and gpGaNTase-T9 depend largely on the peptide's primary structure (for example the presence of multiple clusters of hydroxy amino acids and the number of GalNAc residues attached to the peptide backbone). O-glycosylation in terms of sites of attachment seems to be less random than previously described and, if sequential reactions are ordered throughout the Golgi stack, the complete O-glycosylation of the mucin molecules seems to be finely tuned to respond to specific damage to, or attack on, epithelia.

Cloning and characterization of a ninth member of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase family, ppGaNTase-T9

We have cloned, expressed and characterized the gene encoding a ninth member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family, termed ppGaNTase-T9. This type II membrane protein consists of a 9-amino acid N-terminal cytoplasmic region, a 20-amino acid hydrophobic/transmembrane region, a 94-amino acid stem region, and a 480-amino acid conserved region. Northern blot analysis revealed that the gene encoding this enzyme is expressed in a broadly distributed manner across many adult tissues. Significant levels of 5- and 4.2-kilobase transcripts were found in rat sublingual gland, testis, small intestine, colon, and ovary, with lesser amounts in heart, brain, spleen, lung, stomach, cervix, and uterus. In situ hybridization to mouse embryos (embryonic day 14.5) revealed significant hybridization in the developing mandible, maxilla, intestine, and mesencephalic ventricle. Constructs expressing this gene transiently in COS7 cells resulted in no detectable transferase activity in vitro against a panel of unmodified peptides, including MUC5AC (GTTPSPVPTTSTTSAP) and EA2 (PTTDSTTPAPTTK). However, when incubated with MUC5AC and EA2 glycopeptides (obtained by the prior action of ppGaNTase-T1), additional incorporation of GalNAc was achieved, resulting in new hydroxyamino acid modification. The activity of this glycopeptide transferase is distinguished from that of ppGaNTase-T7 in that it forms a tetra-glycopeptide species from the MUC5AC tri-glycopeptide substrate, whereas ppGaNTase-T7 forms a hexa-glycopeptide species. This isoform thus represents the second example of a glycopeptide transferase and is distinct from the previously identified form in enzymatic activity as well as expression in embryonic and adult tissues. These findings lend further support to the existence of a hierarchical network of differential enzymatic activity within the diversely regulated ppGaNTase family, which may play a role in the various processes governing development.

Mucin gene expression and cell differentiation in human normal, premalignant and malignant esophagus

Esophageal carcinoma includes squamous cell carcinoma and Barrett's adenocarcinoma. The latter usually develops from a premalignant lesion named Barrett's esophagus. MUC genes are known to be specifically expressed in the normal, premalignant and malignant epithelia of various tissues. The aim of this study was to establish the pattern of MUC gene expression in the esophageal mucosa under normal conditions, and under pathological conditions such as squamous cell carcinoma, Barrett's esophagus and adenocarcinoma. Samples of esophageal control mucosa, metaplastic and malignant tissues were obtained from 40 patients undergoing esophagectomy for squamous cell carcinoma (n = 17), or Barrett's esophagus with adenocarcinoma (n = 23). In situ hybridization and northern blot were used with probes specific for the MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7 genes to assess their expression in these samples. Submucosal glands of control esophageal mucosa expressed MUC5B, whereas MUC1 and MUC4 were found in both control epithelium and squamous cell carcinoma. MUC4 expression correlated with squamous cell differentiation. Barrett's adenocarcinoma exhibited various patterns of MUC gene expression, the strongest being in the well-differentiated mucinous adenocarcinomas. Barrett's metaplasia was also associated with a specific MUC gene expression pattern, since the gastric apomucin mRNAs, MUC5AC and MUC6, were expressed in gastric metaplasia, and the intestinal apomucin mRNAs, MUC3, MUC4 and mostly MUC2, in intestinal metaplasia. Residual expression of gastric apomucin mRNAs was found in intestinal metaplasia. From these results, we conclude that MUC genes can be considered reliable phenotypic markers of the esophageal cell differentiation, thus providing new insight into the development of Barrett's esophagus.

Mucin gene expression and cell differentiation in human normal, premalignant and malignant esophagus

Esophageal carcinoma includes squamous cell carcinoma and Barrett's adenocarcinoma. The latter usually develops from a premalignant lesion named Barrett's esophagus. MUC genes are known to be specifically expressed in the normal, premalignant and malignant epithelia of various tissues. The aim of this study was to establish the pattern of MUC gene expression in the esophageal mucosa under normal conditions, and under pathological conditions such as squamous cell carcinoma, Barrett's esophagus and adenocarcinoma. Samples of esophageal control mucosa, metaplastic and malignant tissues were obtained from 40 patients undergoing esophagectomy for squamous cell carcinoma (n = 17), or Barrett's esophagus with adenocarcinoma (n = 23). In situ hybridization and northern blot were used with probes specific for the MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7 genes to assess their expression in these samples. Submucosal glands of control esophageal mucosa expressed MUC5B, whereas MUC1 and MUC4 were found in both control epithelium and squamous cell carcinoma. MUC4 expression correlated with squamous cell differentiation. Barrett's adenocarcinoma exhibited various patterns of MUC gene expression, the strongest being in the well-differentiated mucinous adenocarcinomas. Barrett's metaplasia was also associated with a specific MUC gene expression pattern, since the gastric apomucin mRNAs, MUC5AC and MUC6, were expressed in gastric metaplasia, and the intestinal apomucin mRNAs, MUC3, MUC4 and mostly MUC2, in intestinal metaplasia. Residual expression of gastric apomucin mRNAs was found in intestinal metaplasia. From these results, we conclude that MUC genes can be considered reliable phenotypic markers of the esophageal cell differentiation, thus providing new insight into the development of Barrett's esophagus.

Developmental mucin gene expression in the gastroduodenal tract and accessory digestive glands. II. Duodenum and liver, gallbladder, and pancreas

Studies were undertaken to provide information regarding cell-specific expression of mucin genes and their relation to developmental and neoplastic patterns of epithelial cytodifferentiation. In situ hybridization was used to study mRNA expression of mucin genes in duodenum and accessory digestive glands (liver, gallbladder, pancreas) of 13 human embryos and fetuses (6. 5-27 weeks' gestation), comparing these with normal and neoplastic adult tissues. These investigations demonstrated that the pattern of mucin gene expression in fetal duodenum reiterated the patterns we observed during gastric and intestinal ontogenesis, with MUC2 and MUC3 expression in the surface epithelium and MUC6 expression associated with the development of Brünner's glands. In embryonic liver, MUC3 was already expressed at 6.5 weeks of gestation in hepatoblasts. As in adults, MUC1, MUC2, MUC3, MUC5AC, MUC5B, and MUC6 were expressed in fetal gallbladder, whereas MUC4 was not. In contrast, MUC4 was strongly expressed in gallbladder adenocarcinomas. MUC5B and MUC6 were expressed in fetal pancreas, from 12 weeks and 26 weeks of gestation, respectively. Surprisingly, MUC3 which is strongly expressed in adult pancreas, was not detected in developmental pancreas. Taken together, these data show complex spatio-temporal regulation of the mucin genes and suggest a possible regulatory role for mucin gene products in gastroduodenal epithelial cell differentiation.

[MUC genes: a superfamily of genes? Towards a functional classification of human apomucins]

The MUC genes encode epithelial mucins. Eight different human genes have been well characterized, and two others identified more recently. Among them, a family of four genes, expressed in the respiratory and digestive tracts, is clustered to chromosome 11p15.5; and these genes encode gel-forming mucins which are structurally related to the superfamily of cystine-knot growth factors. A second group is composed of three independent genes encoding various isoforms of mucins including membrane-bound mucins associated to carcinomas. In this second group, MUC3 and MUC4 encode large apomucins containing EGF-like domains.

Acute inflammatory intestinal vascular lesions and in situ abnormalities of the plasminogen activation system in Crohn's disease

OBJECTIVES

The distribution of the intestinal vascular lesions and their relation with the fibrinolysis process are poorly known in Crohn's disease (CD). The mediators of the plasminogen activator system, namely urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1), are a key complex involved in fibrinolysis. The aims of this study were: (1) to further define vascular lesions and their distribution in the intestine; and (2) to study concomitantly the qualitative in situ expression and the levels of u-PA, t-PA and PAI-1 in the ileum of patients with CD.

PATIENTS AND METHODS

Histological, immunohistochemical and ultrastructural studies of vascular lesions in the resected ileum of 27 patients with CD were performed and compared with 36 control patients. Levels of u-PA, t-PA and PAI-1 measured by ELISA methods were compared in healthy and inflamed ileal tissues of 17 patients with CD.

RESULTS

Acute vascular lesions involving mainly serosal venules and capillaries were present in 63% of patients with CD vs 3/36 controls and were associated with PAI-1 expression. They were prominent on the mesenteric border beneath macroscopically normal mucosa. In contrast, chronic vascular lesions were present in all layers beneath mucosal ulcerations, where a significant increase of PAI-1 levels was found.

CONCLUSIONS

These results suggest that vascular involvement associated with abnormalities of PAI-1 expression is an early and widespread event in CD. Their prominence on the mesenteric border might explain the characteristic location of CD ulceration along the mesenteric margin.

Characterization of a UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase that displays glycopeptide N-acetylgalactosaminyltransferase activity

We report the cloning, expression, and characterization of a novel member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family that transfers GalNAc to a GalNAc-containing glycopeptide. Northern blot analysis revealed that the gene encoding this enzyme, termed ppGaNTase-T6, is expressed in a highly tissue-specific manner. Significant levels of transcript were found in rat and mouse sublingual gland, stomach, small intestine, and colon; trace amounts were seen in the ovary, cervix, and uterus. Recombinant constructs were expressed transiently in COS7 cells but demonstrated no transferase activity in vitro against a panel of unmodified peptides, including GTTPSPVPTTSTTSAP (MUC5AC). However, when incubated with the total glycosylated products obtained by action of ppGaNTase-T1 on MUC5AC (mainly GTT(GalNAc)PSPVPTTSTT(GalNAc)SAP), additional incorporation of GalNAc was achieved, resulting in new hydroxyamino acids being modified. The MUC5AC glycopeptide failed to serve as a substrate for ppGaNTase-T6 after modification of the GalNAc residues by periodate oxidation and sodium borohydride reduction, indicating a requirement for the presence of intact GalNAc. This suggests that O-glycosylation of multisite substrates may proceed in a specific hierarchical manner and underscores the potential complexity of the processes that regulate O-glycosylation.

Capillary zone electrophoresis and MALDI-mass spectrometry for the monitoring of in vitro O-glycosylation of a threonine/serine-rich MUC5AC hexadecapeptide

The in vitro N-acetylgalactosaminylation by human gastric UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases was assessed using the peptide motif GTTPSPVPTTSTTSAP, which is found naturally in the tandem repeat domains of the apomucin encoded by the gene MUC5AC. This peptide appeared to be an excellent tool for obtaining an insight into the extensive O-glycosylation processes of apomucins. Up to six N-acetylgalactosamines were added and the given glycopeptide species were well separated by capillary zone electrophoresis. Moreover, the degree of glycosylation (number of monosaccharide O-linked attachments) could be determined by MALDI-mass spectrometry without prior separation. Using different incubation times, we evidenced the accumulation of various glycopeptides, suggesting that the total glycosylation of an apomucin-peptide requires orderly N-acetylgalactosaminylation processing. This information was completed by experimental data showing that N-acetylgalactosaminylated octapeptides (the peptide backbones of which are part of GTTPSPVPTTSTTSAP) were able to selectively inhibit some N-acetylgalactosaminyltransferases. Our results suggest that this inhibition may influence the quality of the intermediate products appearing during the in vitro O-glycosylation process.

Complete sequence of the human mucin MUC4: a putative cell membrane-associated mucin

The MUC4 gene, which encodes a human epithelial mucin, is expressed in various epithelial tissues, just as well in adult as in poorly differentiated cells in the embryo and fetus. Its N-terminus and central sequences have previously been reported as comprising a 27-residue peptide signal, followed by a large domain varying in length from 3285 to 7285 amino acid residues. The present study establishes the whole coding sequence of MUC4 in which the C-terminus is 1156 amino acid residues long and shares a high degree of similarity with the rat sialomucin complex (SMC). SMC is a heterodimeric glycoprotein complex composed of mucin (ascites sialoglycoprotein 1, ASGP-1) and transmembrane (ASGP-2) subunits. The same organization is found in MUC4, where the presence of a GlyAspProHis proteolytic site may cleave the large precursor into two subunits, MUC4alpha and MUC4beta. Like ASGP-2, which binds the receptor tyrosine kinase p185(neu), MUC4beta possesses two epidermal growth factor-like domains, a transmembrane sequence and a potential phosphorylated site. MUC4, the human homologue of rat SMC, may be a heterodimeric bifunctional cell-surface glycoprotein of 2.12 micrometers. These results confer a new biological role for MUC4 as a ligand for ErbB2 in cell signalling.

Abnormalities in mucin gene expression in Crohn's disease

Alterations in the structure and/or quantity of mucins could alter the barrier function of mucus and play a role in initiating and maintaining mucosal inflammation in Crohn's disease. To investigate the hypothesis of a mucin gene defect in Crohn's disease, we analyzed the expression of the different mucin genes in the ileal mucosa of patients with Crohn's disease and controls. mRNA expression levels were assessed by a quantitative dot blot analysis and compared (i) between healthy and involved ileal mucosa of patients with Crohn's disease and (ii) between healthy mucosa of patients with Crohn's disease and controls. Expression of the different mucin genes was heterogeneous among controls and patients with Crohn's disease, except for MUC6 in controls. Nevertheless, MUC1 mRNA expression was significantly decreased in the involved ileal mucosa of patients with Crohn's disease when compared to the healthy mucosa (p = 0.02). Moreover, the expression levels of MUC3, MUC4, and MUC5B were significantly lower in both healthy and involved ileal mucosa of patients with Crohn's disease compared to controls (p < or = 0.05). The decrease of expression levels of some mucin genes (more particularly MUC3, MUC4, and MUC5B) in both healthy and involved ileal mucosa suggests a primary or very early mucosal defect of these genes in CD.

Abnormalities in mucin gene expression in Crohn's disease

Alterations in the structure and/or quantity of mucins could alter the barrier function of mucus and play a role in initiating and maintaining mucosal inflammation in Crohn's disease. To investigate the hypothesis of a mucin gene defect in Crohn's disease, we analyzed the expression of the different mucin genes in the ileal mucosa of patients with Crohn's disease and controls. mRNA expression levels were assessed by a quantitative dot blot analysis and compared (i) between healthy and involved ileal mucosa of patients with Crohn's disease and (ii) between healthy mucosa of patients with Crohn's disease and controls. Expression of the different mucin genes was heterogeneous among controls and patients with Crohn's disease, except for MUC6 in controls. Nevertheless, MUC1 mRNA expression was significantly decreased in the involved ileal mucosa of patients with Crohn's disease when compared to the healthy mucosa (p = 0.02). Moreover, the expression levels of MUC3, MUC4, and MUC5B were significantly lower in both healthy and involved ileal mucosa of patients with Crohn's disease compared to controls (p < or = 0.05). The decrease of expression levels of some mucin genes (more particularly MUC3, MUC4, and MUC5B) in both healthy and involved ileal mucosa suggests a primary or very early mucosal defect of these genes in CD.

Relevance of sialoglycoconjugates in murine thymocytes during maturation and selection in the thymus

Differentiation of most T lymphocytes is characterized not only by the variable expression of CD4/CD8 coreceptor molecules and increased surface density of the T cell antigen receptor, but also by changes in the glycosylation pattern of cell surface glycolipids or glycoproteins. In this work we evaluated the changes in the sialylation pattern in thymus sections from normal and dexamethasone treated mice. We used sialic acid specific lectins, such as Sambucus nigra agglutinin (SNA, NeuAcalpha2,6-Gal specific) and Maackia amurensis agglutinin (MAA, NeuAcalpha2,3-Gal specific). Our results indicate that the sialylation pattern was modified during the maturation process of thymic cells. The immature CD4-CD8- and CD4+CD8+ cortical thymocytes were recognized by SNA, whereas the mature single positive (CD4+ or CD8+) medullary cells, preferentially bound MAA lectin. However, in the corticomedullary region we found not only SNA+ cells, but also MAA+ cells. In the thymus of dexamethasone treated mice, the clusters of thymocytes undergoing apoptosis in the cortex were characteristically stained by SNA. These results suggest that in the initial stages of the differentiation pathway, a great number of thymocytes express an alpha2,6 linked sialic acid on their surface and as they progress to more mature stages there is a change in the sialylation pattern to alpha2,3 linked sialic acids probably due to a regulated expression of different sialyltransferases, which could be modulated by the thymic microenvironment.

Permanent exposure of mucin-secreting HT-29 cells to benzyl-N-acetyl-alpha-D-galactosaminide induces abnormal O-glycosylation of mucins and inhibits constitutive and stimulated MUC5AC secretion

Previous work has shown that treatment of HT-29 methotrexate (MTX) cells with benzyl-N-acetyl-alpha-D-galactosaminide results in profound changes in mucin oligosaccharide chains. To analyse in depth the effect of this drug, we first determined the structure of mucin oligosaccharide chains synthesized by HT-29 MTX cells and the changes induced by permanent drug exposure. Mucins from untreated cells contained nine monosialylated structures (core types 1, 2, 3 and 4) and four disialylated structures (types 1, 2 and 4). Core 1 structures predominated, in particular NeuAcalpha2-3Galbeta1-3GalNAc-ol. Exposure of HT-29 MTX cells to benzyl-N-acetyl-alpha-D-galactosaminide from days 2-21 resulted in a decrease in intracellular mucins and both their sialic acid and galactose content, and an increased T (Galbeta1-3GalNAcalpha-O-Ser/Thr) and Tn (GalNAcalpha-O-Ser/Thr) antigenicity. A 3-fold increase in both Galbeta1-3GalNAc alpha2, 3-sialyltransferase activity and mRNA expression was detected. At the ultrastructural level, T-antigen was not detectable in mucin droplets in control cells, but was strongly expressed in intracytoplasmic vesicles in treated cells. In these cells, MUC1 and MUC3 transcripts were up-regulated, whereas MUC2, MUC5B and MUC5AC were down-regulated. Furthermore, constitutive and secretagogue-induced MUC5AC secretion was reduced and no mucus layer was detected. In conclusion, benzyl-N-acetyl-alpha-D-galactosaminide induces abnormal O-glycosylation and altered regulation of MUC5AC secretion.

Human mucin gene MUC4: organization of its 5'-region and polymorphism of its central tandem repeat array

In a previous study we isolated a partial cDNA with a tandem repeat of 48 bp, which allowed us to map a novel human mucin gene named MUC4 to chromosome 3q29. Here we report the organization and sequence of the 5'-region and its junction with the tandem repeat array of MUC4. Analysis of three overlapping genomic clones allowed us to obtain a partial restriction map of MUC4 and to locate the complete 48 bp tandem repeat domain on a PstI/EcoRI genomic fragment that exhibits a very large variation in number of tandem repeats (7-19 kb). cDNA clonal extension allowed us to obtain the entire 5' coding region of MUC4. Exon 1 consists of a 5' untranslated region and an 82 bp fragment encoding the signal peptide. This latter shows a high degree of similarity to the signal peptide of another apomucin, ASGP-1. Exon 2 is extremely large and contains a unique sequence that is followed by the whole tandem repeat domain. It encodes only one cysteine residue, making MUC4 different from mucin genes belonging to the 11p15.5 family. Moreover, an intron downstream from the tandem repeat array consists mainly of a 15 bp tandem repeat that exhibits a polymorphism in having a variable number of tandem repeats.

Genomic organization of the 3'-region of the human MUC5AC mucin gene: additional evidence for a common ancestral gene for the 11p15.5 mucin gene family

The human mucin gene MUC5AC is mapped clustered with MUC2, MUC5B and MUC6 on chromosome 11p15.5. We report here the isolation and characterization of a genomic cosmid clone, designated ELO9, spanning the 3'-region of MUC5AC and the 5'-region of MUC5B, allowing us to conclude that MUC5AC and MUC5B have the same transcriptional orientation. We determined the genomic organization and the entire sequence of the 3'-region of MUC5AC. The comparative molecular analysis of MUC5AC and MUC5B points to a remarkable similarity in the size and the distribution of exons, and in the type of splice sites, supporting the notion that MUC5AC and MUC5B have evolved from a single common ancestral gene. The derivation of the four genes of the 11p15.5 mucin gene family from a single ancestral gene is discussed.

Metabolic studies in a patient with severe carnitine palmitoyltransferase type II deficiency

Here we report on a patient with severe ("non-classic") carnitine palmitoyltransferase type II (CPT II) deficiency. Hypoglycemia prompted by an infectious episode and associated with non-ketotic dicarboxylic aciduria orientated diagnosis towards beta-oxidation deficiency disorders. Blood carnitine levels revealed a secondary carnitine deficiency that was responsive to oral L-carnitine supplementation. Blood acylcarnitine profiles were abnormal and included acetyl (C2:0), butyryl/isobutyryl (C4:0), isovaleryl/2-methylbutyryl (C5:0), hexanoyl (C6:0), myristoyl (C14:0), palmitoyl (C16:0), hexadecenoyl (C16:1), oleyl (C18:1) and stearoyl (C18:0) carnitine. In urine, excess excretion of dicarboxylylcarnitines, mainly dodecanedioylcarnitine, was noticed. Upon carnitine supplementation, C8 to C12 fatty acylcarnitines, with decanoylcarnitine as well as C10 to C14 dicarboxylylcarnitines being prominent, were observed in urine. Biochemical measurements disclosed a severe reduction of mitochondrial CPT II activity (7% of normal values). Correlations of metabolic findings in the patient and physiological roles of CPT II are briefly discussed.

Dipeptidyl aminotransferase activity and in vitro O-glycosylation of MUC5AC mucin motif peptides by human gastric microsomal preparations

The in vitro O-glycosylation reaction of the MUC5AC mucin motif peptide, TTSAPTTS (in one-letter code), was achieved with human gastric microsomal homogenates. The analyses using capillary electrophoresis online coupled with electrospray mass spectrometry and further Edman degradation of the purified products (obtained by capillary electrophoresis at preparative scale) allowed us to distinguish two components at close masses: the addition of a mass of 202 corresponded to an N-terminal elongation of the peptide TTSAPTTS with the dipeptide (TT) and the addition of a mass of 203 corresponded to an N-acetylgalactosamine O-linkage. Using different peptidase inhibitors, a dipeptidyl peptidase/transferase activity was further characterized. A thiol dependence and an inhibition by H-Gly-PheCHN2 (specific to cathepsin C activity) were found. Moreover, besides TTSAPTTS, other MUC5AC motif peptides (GTTPSPVP, TSAPTTS) were also dipeptide donors (GT and TS, respectively) and our results suggested the involvement of a single dipeptidyl peptidase/transferase activity. Finally, this latter activity modified the in vitro GalNAc incorporation rates when using our selected MUC5AC motif peptides. Our study therefore shows that caution must be taken to prevent peptidic substrate elongation while performing in vitro O-glycosylation with microsomal preparations as the enzyme source. In fact, the results of the N-acetylgalactosamine incorporation rates and thus the microsomal N-acetylgalactosamine transferase affinity can be misinterpreted if dipeptidyl peptidase/transferase activity is not inhibited by the thiol inhibitor E-64 or the cathepsin C inhibitor H-Gly-PheCHN2.

Improved capillary electrophoretic separation of glycosylated oligopeptides through addition of poly(vinyl alcohol), and analysis by electrospray mass spectrometry

A method for the analysis of O-glycosylation of peptides has been developed, combining capillary electrophoretic (CE) separation and electrospray ionization mass spectrometry. Synthetic peptides with apomucin 'tandem repeat' sequences which present potential O-glycosylation sites on threonine and serine residues were used as model system. In vitro O-glycosylated peptide samples were obtained by incubation of the peptides with human gastric microsomal homogenates containing N-acetylgalactosamine transferase activity in the presence of uridyl diphosphate N-acetylgalactosamine (UDP-GalNAc). CE was carried out in the presence of the linear polymer poly(vinyl alcohol) in the electrophoresis solvent, resulting in a greatly improved separation of the up to five different glycoforms of peptides with lengths of 8, 16 or 23 amino acids, and the unglycosylated peptides. After separation and peak collection, the number of modifications with N-acetyl galactosamine (GalNAc) could be determined by electrospray ionization mass spectrometry. The glycosylation pattern was shown to depend on the amino acid sequence of the peptides.

Influence of the amino acid sequence on the MUC5AC motif peptide O-glycosylation by human gastric UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase(s)

The present work was carried out to study the role of the peptide moiety in the addition of O-linked N-acetylgalactosamineto human apomucin using human crude microsomal homogenates from gastric mucosa (as enzyme source) and a series of peptide acceptors representative of tandem repeat domains deduced from the MUC5AC mucin gene (expressed in the gastric mucosa). Being rich in threonine and serine placed in clusters, these peptides provided several potential sites for O-glycosylation. The glycosylated products were analysed by a combination of electrospray mass spectrometry and capillary electrophoresis in order to isolate the glycopeptides and to determine their sequence by Edman degradation. The O-glycosylation of our MUC5AC motif peptides gave information on the specificity and activity of the gastric microsomal UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferase(s). The proline residues and the induced-conformations are of great importance for the recognition of MUC5AC peptides but they are not the only factors for the choice of the O-glycosylation sites. Moreover, for the di-glycosylated peptides, the flanking regions of the proline residues strongly influence the site of the second O-glycosylation.

Evolutionary history of the 11p15 human mucin gene family

The four human mucin genes MUC6, MUC2, MUC5AC, and MUC5B are located at chromosome 11p15.5. It has been demonstrated that the three mucins MUC2, MUC5AC, and MUC5B contain several Cys-subdomains of 108 amino acid residues. In contrast, little information is available concerning MUC6. These Cys-subdomains contain 10 cysteine residues that have a highly conserved position. We present here a coherent probable evolutionary history of this human gene family after comparison of the nucleotide sequences of these Cys-subdomains. The three MUC loci MUC2, MUC5AC, and MUC5B may have evolved from a common ancestral gene by two successive duplications. Moreover, we can postulate that MUC5AC and MUC5B have evolved in a concerted manner, while MUC2 has evolved separately.

Polypeptide:N-acetylgalactosaminyltransferase activities towards the mucin MUC5AC peptide motif using microsomal preparations of normal and tumoral digestive mucosa

The selected-acceptor substrate peptide (TTSAPTTS), deduced from the human mucin gene MUC5AC (expressed essentially in the human gastric and tracheobronchial mucosa), was used to assay polypeptide:N-acetylgalactosaminyltransferases (GalNAc transferases) of different microsomal preparations, obtained from gastric and colonic mucosa in normal and tumoral situations. The O-glycosylated products, analyzed by capillary electrophoresis and electrospray mass spectrometry, showed a variable number of GalNAc O-linked to the different hydroxy amino acids of TTSAPTTS, depending on the tissue studied. Our observations were consistent with the existence of more than one form of GalNAc transferases which were expressed differentially in the gastrointestinal tract (stomach and/or colon). The levels of enzyme activities showed a tissue-specific pattern as they were high in normal colonic tissue and low in colon cancer. On the other hand, in the tumoral gastric tissue (displaying intestinal metaplasia) a high level of GalNAc transferase activities was obtained, similar to that found in the normal colon. Moreover, slight discrepancies (activities and number of O-linked GalNAc) were only detected between normal gastric and tumoral colonic preparations. Thus, the data indicated that the dedifferentiation of the gastric cancer tissue may induce GalNAc transferase activities similar to those in the normal colonic, tissue and that colonic and gastric tissues may contain families of glycosyltransferases involved specifically in reaction towards particular peptide or protein substrates. In addition, the analysis by capillary electrophoresis and electrospray mass spectrometry revealed, in tumoral gastric as well as in normal colonic tissues, a high dipeptidylaminotransferase activity inducing an elongation of TTSAPTTS by dithreonine. This activity was low in normal gastric and tumoral colonic tissues.

Mucin gene expression in biliary epithelial cells

BACKGROUND/AIMS

In recent years considerable advances have been made in our knowledge of human mucin genes. Although analysis of their genomic organization is still in progress, the pattern of their expression in different human mucosae is now fairly well established. However, little is known about their expression in the biliary tree. In this study we determined the pattern of expression of the different human mucin genes in gallbladder biliary epithelial cells, intrahepatic bile ducts and liver.

METHODS

Two complementary methods were used: Northern-blot and in situ hybridization analyses. The experiments were performed with eight probes corresponding to MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7.

RESULTS

Our results revealed a strong mRNA expression of MUC3, MUC6 and MUC5B, a weak expression of MUC1, MUC5AC and MUC2, and no expression of MUC4 and MUC7. Surprisingly, MUC3, which was the gene which was most expressed in the biliary tree, was also found in hepatocytes, suggesting another function for the MUC3 protein than that of a secreted mucin.

CONCLUSIONS

We conclude that MUC3, MUC6 and MUC5B were the main mucin genes expressed in biliary epithelial cells.

O-Glycosylation and cellular differentiation in a subpopulation of mucin-secreting HT-29 cell line

Malignant transformation of epithelial cells is associated with abnormal glycosylation of mucins. The aim of this work was to evaluate the changes in the O-glycosylation processes during differentiation of tumor cells by performing in vitro reactions using crude microsomal preparations obtained from a subpopulation of HT-29 cells capable of differentiating into mucin-secreting cells (HT-29 MTX cells). The reactions of O-glycosylation were carried out at different times of culture: before confluence (Day 5), when cells are still undifferentiated, and after confluence (Day 21), when cells display a mucin-secreting phenotype. As acceptor for the UDP-N-acetylgalactosamine:polypeptide Nacetylgalactosaminyltransferase (GalNAc transferase), the peptide motif TTSAPTTS (tandem repeat deduced from MUC5AC human gastric gene, expressed in HT-29 MTX cells) was used. A higher rate of enzyme activity was observed in preconfluent cells, and analysis by capillary electrophoresis and electrospray mass spectrometry showed a different pattern of galactosaminylation in pre- and postconfluent cells. Core 1 UDP-galactose:N-acetyl-alpha-galactosaminyl-R 3-beta-galactosyltransferase (3-beta-galactosyltransferase) activityalso decreased with the differentiation, whereas CMP-neuraminic acid:galactose-beta-1, 3-N-acetyl-alpha-galac- tosaminyl-R 3-alpha-sialyltransferase activity increased. In comparison, the evolving process of mucin biosynthesis was tested by the analysis of purified mucins of HT-29 MTX cells, in amino acid and carbohydrate composition, and immunoreactivity assays using several antibodies and lectins. The results suggested that (i) no mucins were detected at Day 5, while the GalNAc transferase and 3-beta-galactosyltransferase activities were already at high rates; (ii) the mucins purified from postconfluent cells showed a high content of sialic acid in an alpha-2,3-linkage to galactose residues; and (iii) cellular differentiation seemed to be accompanied by more regulated processes of glycosylation. This study of the O-glycosylation in HT-29 MTX cells is thus an interesting approach to analyzing the regulation of mucin biosynthesis during cellular differentiation.

Human mucin genes assigned to 11p15.5: identification and organization of a cluster of genes

Four distinct genes that encode mucins have previously been mapped to chromosome 11p15.5. Three of these genes (MUC2, MUC5AC, and MUC6) show a high level of genetically determined polymorphism and were analyzed in the CEPH families. Linkage analysis placed all three genes on the genetic map in a cluster between HRAS and INS, and more detailed analysis of recombinant breakpoints revealed that MUC6 is telomeric to MUC2. Using these recombinants D11S150 was mapped close to MUC2. Ten of the 11 recombinant chromosomes studied in detail were paternal, and the recombinant events were distributed throughout the 11p15 region, suggesting that the high level of recombination observed in 11p15.5 is not due to a particular recombinational hot spot. Pulsed-field gel electrophoresis was used to make a detailed physical map of the MUC cluster and to integrate the physical and genetical maps. The gene order was determined to be HRAS-MUC6-MUC2-MUC5AC-MUC5B-IGF2. The MUC genes span a region of some 400 kb and the map extends 770 kb and contains 15 putative CpG islands. The order of the MUC genes on the map corresponds to the relative order of their expression along the anterior-posterior axis of the body, suggesting a possible functional significance to the gene order.

Metabolic studies in twin brothers with 2-methylacetoacetyl-CoA thiolase deficiency

We report clinical and biological investigations in two patients (twin brothers) with 2-methylacetoacetyl-CoA thiolase deficiency. Main clinical features included important staturo-ponderal delay, frequent infectious rhinopharyngitis episodes and an acute metabolic acidosis at the age of 4 years, this metabolic decompensation being adequately halted by bicarbonate supplementation. Since that age, patients developed rather favorably, however, with persistence of the staturo-ponderal delay. Organicaciduria typical of 2-methylacetoacetyl-CoA thiolase deficiency was recorded consisting of excessive excretion of tiglylglycine, 2-methyl-3-hydroxybutyrate, 3-hydroxyisovalerate, 2-methylglutaconate, adipate and 2-methylacetoacetate. Blood carnitine levels were altered in patients with increased total and esterified carnitine concentrations and enhanced acyl/free carnitine ratios. Determination of acylcarnitine profiles showed that patients excreted excessive amounts of several acylcarnitines in urine including propionyl, butyryl, isobutyryl, isovaleryl, 2-methylbutyryl and tiglyl-carnitine, the latter acylcarnitine being prominent with, in one of the patients, occurrence of a previously undescribed isomer of this carnitine ester, possibly 2-ethylacrylyl-carnitine. Excretion of these acylcarnitines in urine was increased in response to L-carnitine although, as a whole, this therapy resulted in a less important stimulation of esterified carnitine removal in urine from patients than in the case of supplemented controls. Biochemical investigations on cultured skin fibroblasts confirmed 2-methylacetoacetyl-CoA thiolase deficiency. Through the present report on this rare disease in two siblings, we would like to underline that acylcarnitines can be used in the diagnosis of 2-methylacetoacetyl-CoA thiolase deficiency, a view supported by acylcarnitine profiles further determined in another patient with proven oxothiolase deficiency, adding this pathology to the list of beta-oxidation disorders that may be screened successfully through determination of acylcarnitine profiles in body fluids.

Regulation of cathepsin D dependent on the phenotype of colon carcinoma cells

We have studied the intracellular trafficking of cathepsin D in different colon carcinoma cell populations: the HT-29 cell line, composed of >95% undifferentiated cells; 2 subpopulations derived from this cell line, containing cells committed to differentiation into mucin-secreting cells (HT-29 MTX) or enterocyte-like cells (HT-29 G-) after confluence; and the Caco-2 cell line, which spontaneously differentiates into enterocyte-like cells after confluence. Post-confluent undifferentiated HT-29 cells and differentiated enterocyte-like HT-29 G- and Caco-2 cells secrete significant levels of cathepsin D in culture medium, in contrast to post-confluent differentiated mucin-secreting HT-29 MTX cells, which secrete this enzyme at a very low level. The intracellular content and the mRNA level of cathepsin D increase after confluence in the different cell types, particularly in Caco-2 cells, which intensify the secretion of cathepsin D along with the differentiation process post-confluence. Membrane-associated mature cathepsin D was detected in HT-29 cells but not in Caco-2 cells. In the different types of cell, pro-cathepsin D associates with the membrane concomitantly to its binding to an Mr 72,000 protein. Membrane association persists after dissociation of the complex in HT-29 cells but not in Caco-2 cells. In the mucin-secreting HT-29 MTX cells, cathepsin D was immunolocalised to the membrane of mucin vacuoles localised under the brush border. Our results show that cathepsin D can be regulated differently in colon carcinoma cells, and this finding might have specific functional implications for each cell type.

Benzyl-N-acetyl-alpha-D-galactosaminide inhibits the sialylation and the secretion of mucins by a mucin secreting HT-29 cell subpopulation

We have analysed the mucins synthesized by the HT-29 MTX cell subpopulation, derived from the HT-29 human colon carcinoma cells through a selective pressure with methotrexate (Lesuffleur et al., 1990, Cancer Res 50: 6334-43), in the presence of benzyl-N-acetyl-alpha-galactosaminide (GalNAc alpha-O-benzyl), which is a potential competitive inhibitor of the beta 1,3-galactosyltransferase that synthesizes the T-antigen. The main observation was a 13-fold decrease in the sialic acid content of mucins after 24 h of exposure to 5 mM GalNAc alpha-O-benzyl. This effect was accompanied by an increased reactivity of these mucins to peanut lectin, testifying to the higher amount of T-antigen. The second observation was a decrease in the secretion of the mucins by GalNAc alpha-O-benzyl treated cells. The decrease in mucin sialylation was achieved through the in situ beta-galactosylation of GalNAc alpha-O-benzyl into Gal beta 1-3GalNAc alpha-O-benzyl, which acts as a competitive substrate of Gal beta 1-3GalNAc alpha 2,3-sialyltransferase, as shown by the intracellular accumulation of NeuAc alpha 2-3Gal beta 1-3GalNAc alpha-O-benzyl in treated cells.

Acylcarnitine removal in a patient with acyl-CoA beta-oxidation deficiency disorder: effect of L-carnitine therapy and starvation

Carnitine levels and acylcarnitine profiles in a patient with mild multiple acyl-CoA dehydrogenase deficient beta-oxidation were compared with control results. Whereas blood and urine total carnitine levels were moderately decreased, blood esterified carnitine levels in the patient were about 2-fold higher than in controls. Urinary acylcarnitine profiles presented with a larger variety of carnitine esters than in controls and included propionylcarnitine, butyrylcarnitine, 2-methylbutyrylcarnitine, hexanoylcarnitine and octanolycarnitine. Total carnitine levels in body fluids were similarly affected by chronic oral L-carnitine administration in patient and controls. By contrast, esterified carnitine level increase was 2-fold more important in controls than in patient. Whereas no qualitative changes in urinary acylcarnitine profiles were induced by L-carnitine therapy in controls, several alterations of these profiles were observed in the patient. The effect of starvation on metabolites was also studied, especially beta-oxidation rates assessed by free fatty acids to 3-hydroxybutyric acid ratios in blood from the patient in the untreated and L-carnitine treated states. In the L-carnitine-supplemented patient, the effect of starvation on the time course of carnitine levels and acylcarnitine profiles could also be documented. The ability of chronic oral L-carnitine administration to remove relatively less important amounts of acylcarnitines in the patient than in controls is further discussed, as well as qualitative alterations of acylcarnitine profiles induced by this therapy in the pathological condition.

[Glycoforms of alpha-1 antichymotrypsin in infectious process. Diagnostic value and follow-up]

OBJECTIVES

Three alpha 1-antichymotrypsin (alpha 1-ACT) glycans have been identified. We followed their levels during the septic processes in 24 patients in order to determine their diagnostic value in correlation with C-reactive peptide in patients with infection.

METHODS

Sera were collected for assay on days 0, 3 and 6 after starting antibiotics. Erythrocyte sedimentation rate, alpha 1-ACT and C-reactive protein were determined.

RESULTS

Erythrocyte sedimentation rate changed little while C-reactive protein fell sharply as in other inflammatory processes. Crossed immunoaffinoelectrophoresis showed a decreased formation of the Con-A non reactive fraction which disappeared rapidly after initiating antibiotics. Glycan microheterogeneity returned to normal at 6 days while C-reactive protein and alpha 1-ACT were still elevated.

CONCLUSION

Synthesis and glycosylation of alpha 1-ACT are independent. Study of alpha 1-ACT glycan microheterogeneity may provide a useful test in the diagnosis of inflammatory processes of unknown origin and may be helpful in following-up patients with sepsis.

Aberrant expression of a human mucin gene (MUC5AC) in rectosigmoid villous adenoma

BACKGROUND & AIMS

Rectosigmoid villous adenomas (RVAs) account for approximately 10% of all colorectal tumors. They have distinct pathological features, including abundant mucus secretion, possible malignant transformation, and multiple recurrences after conservative treatment. The aim of this study was to determine the nature of any changes in mucin gene expression in RVAs.

METHODS

In situ hybridization was used to examine mucin messenger RNA expression in a series of 22 patients with an RVA. Five normal rectal and colonic mucosae and five rectal adenocarcinomas were used as controls.

RESULTS

In the 22 RVAs, we found an overexpression of MUC2 and an aberrant expression of MUC5AC. This MUC5AC expression was more intense in RVAs with low-grade dysplasia than in those cases with high-grade dysplasia. Moreover, in 4 cases, it was detected at a distance from the tumor in areas previously considered as normal by endoscopic and histological examination.

CONCLUSIONS

MUC5AC seems to be a specific marker for RVAs and thus may be useful for the early detection of RVA recurrences after endoscopic laser treatment.

Identification of hyaluronic acid and chondroitin sulfates in human follicular fluid and their effects on human sperm motility and the outcome of in vitro fertilization

This study measured glycosaminoglycans (GAGs) in human follicular fluid (hFF) obtained from patients undergoing hormonal stimulation with combined GnRH agonist followed by gonadotropin hormone (hMG or FSH) for in vitro fertilization (IVF). The GAGs were partially characterized through the use of various mucopolysaccharidases and then their effects tested on human sperm motility. In hFF, the GAG and protein concentrations were 4.4 +/- 1.3 mg/L and 32.6 +/- 3.2 g/L respectively. Chondroitins (CS) and hyaluronic acid (HA) significantly stimulate sperm motion in comparison to the control. The oocytes inseminated with GAGs-pretreated spermatozoa showed a significantly higher rate of cleavage and pregnancy or delivered number. The present results suggest that hFF is a rich source of sulfated glycosaminoglycan (CS), and non-sulfated glycosaminoglycan (HA). The stimulatory effects of hFF on human sperm motility may well depend on CS and HA. GAGs pretreated sperm may enhance the fertilizing ability of spermatozoa and thus the IVF outcome.

Relationship between a mild alpha 1 proteinase inhibitor deficiency and respiratory symptoms in a family

A 34-year-old man with pulmonary emphysema was found to have a mild alpha 1 proteinase inhibitor (alpha 1 PI) deficiency. alpha 1 PI status was investigated in this patient and in 35 members of his family. The alpha 1 PI investigations included alpha 1 PI concentration and phenotype and serum inhibitory capacity for trypsin and pancreatic elastase. Fifteen members of the family had alpha 1 PI concentration and inhibitory capacities below the lower normal limit. Five of these members were characterized by the heterozygous MP phenotype and the 10 others by an apparently homozygous M phenotype, in which the M allele may be associated with another unidentified deficiency allele. Two members of the family had alpha 1 PI concentration and elastase inhibitory capacity below the lower normal limits and trypsin inhibitory capacity within the normal range. They were both characterized by the MP phenotype. Six of these 17 members (three of PI type M and three of PI type MP) showed chronic pulmonary symptoms, whereas among the 19 alpha 1 PI non deficient members, no member had a history of significant pulmonary symptoms.

Characterization of mucins and proteoglycans synthesized by a mucin-secreting HT-29 cell subpopulation

HT-29 cells selected by adaptation to 10(−5) M methotrexate (HT-29 MTX) are a homogeneous cell population producing high amounts of mucin. Intracellular mucins and proteoglycans were isolated from these cells by ultracentrifugation of cell lysates on a cesium bromide gradient and further separated by anion-exchange high performance liquid chromatography. The major mucin fraction isolated was characterized by a high hydroxy amino acid content (40%), a Thr/Ser ratio of 1.52, a high sialic acid content, and a low sulfate content. When the same procedure was applied to undifferentiated HT-29 cells, a minor mucin fraction was isolated which appeared less sialylated and more sulfated. The major proteoglycan species identified in HT-29 MTX cells showed less acidic behavior than the proteoglycan isolated from HT-29 cells. The effect of brefeldin A and the sugar analog GalNAc-alpha-O-benzyl on the synthesis and biochemical properties of mucins synthesized by HT-29 MTX cells was examined. Brefeldin A induced the synthesis of more-sulfated mucins. GalNAc-alpha-O-benzyl treatment resulted in mucins with an increased content of T antigen and a 13-fold lower sialic acid content. We show that GalNAc-alpha-O-benzyl was metabolized by the cells to Gal beta 1–3GalNAc-alpha-O-benzyl, which, in turn, was a potent competitive inhibitor of the O-glycan alpha-2,3-sialyltransferase. These results illustrate the suitability of HT-29 MTX cells as a model to analyse mucin synthesis and sialylation.

Characterization of the human mucin gene MUC5AC: a consensus cysteine-rich domain for 11p15 mucin genes?

To date five human mucin cDNAs (MUC2, 5A, 5B, 5C and 6) mapped to 11p15.3-15.5, so it appears that this chromosome region might contain several distinct gene loci for mucins. Three of these cDNAs, MUC5A, B and C, were cloned in our laboratory and previously published. A common number, 5, was recommended by the Human Gene Mapping Nomenclature Committee to designate them because of their common provenance from human tracheobronchial mucosa. In order to define whether they are products of the same gene locus or distinct loci, we describe in this paper physical mapping of these cDNAs using the strategy of analysis of CpG islands by pulse-field gel electrophoresis. The data suggest that MUC5A and MUC5C are part of the same gene (called MUC5AC) which is distinct from MUC5B. In the second part of this work, complete sequences of the inserts corresponding to previously described (JER47, JER58) and novel (JER62, JUL32, MAR2, MAR10 and MAR11) cDNAs of the so-called MUC5AC gene are presented and analysed. The data show that in this mucin gene, the tandem repeat domain is interrupted several times with a subdomain encoding a 130 amino acid cysteine-rich peptide in which the TR3A and TR3B peptides previously isolated by Rose et al. [Rose, Kaufman and Martin (1989) J. Biol. Chem., 264, 8193-8199] from airway mucins are found. A consensus peptide sequence for these subdomains involving invariant positions of most of the cysteines is proposed. The consensus nucleotide sequence of this subdomain is also found in the MUC2 gene and in the MUC5B gene, two other mucin genes mapped to 11p15. The functional significance for secreted mucins of these cysteine-rich subdomains and the modular organization of mucin peptides are discussed.

Analysis by electrospray mass spectrometry of glycopeptides from the in vitro O-glycosylation reaction using human mucin motif peptide

A mucin-motif peptide in the one-letter code T T T P S P P M T T P I T P P A, representative of the human intestinal mucin tandem repeat sequence (MUC2), containing several threonine residues in clusters, was used as an acceptor substrate to investigate the effect of peptide structure on the activity of crude preparation of human gastric UDP-GalNAc:polypeptide N-acetyl galactosaminyltransferases. High-performance liquid chromatography was performed to separate the different products of the in vitro O-glycosylated reaction. The electrospray mass spectrometry was used to identify the different masses (m/z) of these products. Although the m/z of glycopeptide(s) could be higher than the detection limits of the spectrometer, an accurate study of the doubly charged ions allowed us to demonstrate the linkage of more than two sugars. Hence, the peptide MUC2 will accept at least four carbohydrate residues but the exact substituted positions should be confirmed by further sequence determination.

Combination of high-performance anion-exchange chromatography and electrospray mass spectrometry for analysis of the in vitro O-glycosylated mucin motif peptide

Reversed-phase high-performance liquid chromatography (HPLC) and high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection were developed for the study of products obtained from the in vitro O-glycosylation of a mucin motif peptide, TTSAPTTS, the most representative sequence encoded by the human gene MUC5C. After incubation of the peptide, which is rich in clustered hydroxyamino acids, by both human colonic and gastric microsomal homogenates, the glycosylated products were separated by HPLC and HPAEC and analysed by electrospray mass spectrometry (ES-MS). The combination of HPAEC and ES-MS was the approach used for evaluating the differences between the polypeptide N-acetylgalactosaminyltransferase activity in different digestive tissues.

Vitamin A and E blood levels in erythrodermic and pustular psoriasis associated with chronic alcoholism

Vitamin A and E blood levels were determined, using a high-performance liquid chromatographic method, in 7 patients with erythrodermic psoriasis or psoriatic acral pustulosis associated or not associated with chronic alcoholism, during and after the acute episode. These vitamins were also studied in 5 patients with psoriasis vulgaris involving more than 80% of the surface body area and associated with chronic alcohol intake and in 17 patients with psoriasis vulgaris involving more than 50% of the skin but without chronic alcoholism. Vitamin A blood levels were reduced in all the patients in the group "erythrodermic psoriasis/psoriatic acral pustulosis", while vitamin E blood levels were below the normal range during the acute psoriatic episode only in the 5 patients having a history of chronic alcohol intake in this group. In the other groups--psoriasis vulgaris with chronic alcoholism and psoriasis vulgaris without heavy alcohol consumption--vitamin A and E blood levels were not reduced. The implication of vitamin E in psoriasis, probably by its antioxidant activity, and its relationship with selenium are discussed. We suggest that attention should be paid to the vitamin A deficiency in erythrodermic or pustular psoriasis and to the vitamin E deficiency when these inflammatory diseases are associated with chronic alcoholism.