Heart failure among people with Type 2 diabetes mellitus: real-world data of 289 954 people from a diabetes database.

AIM: Comparing people with Type 2 diabetes mellitus with and without heart failure in terms of metabolic control, therapeutic regimen and comorbidities. METHODS: The Prospective Diabetes Registry (DPV) is a longitudinal documentation system for demographics, medical care and outcome in people with diabetes mellitus. It consists of follow-up data from people with diabetes mellitus who have agreed to be recorded in the registry. Clinical data are submitted by general practitioners, specialists and clinics throughout Germany and Austria. Some 289 954 people with Type 2 diabetes mellitus (years 2000 to 2015) were analysed using demographic statistics and adjustment for confounders based on linear and logistic regression analysis. RESULTS: People with Type 2 diabetes mellitus (ICD code: E11) and heart failure (ICD code: I50) (N = 14 723) were older, more often women and presented with longer diabetes duration compared with those without heart failure. After adjustment for age, gender and diabetes duration, people with heart failure showed lower HbA1c , higher BMI and more intense insulin therapy. Analysis revealed that people with heart failure were more often treated with insulin, and more frequently received anti-hypertensives and lipid-lowering medication. They presented with lower systolic and diastolic BP. People with heart failure more frequently showed a history of comorbidities. CONCLUSION: Heart failure is common in diabetes mellitus, but the prevalence in the DPV is lower frequent than expected. The reason for improved metabolic control in heart failure may be intensified therapy with insulin, lipid-lowering medication and anti-hypertensives in this cohort.

Hyperglycemia exacerbates colon cancer malignancy through hexosamine biosynthetic pathway.

Hyperglycemia is a common feature of diabetes mellitus, considered as a risk factor for cancer. However, its direct effects in cancer cell behavior are relatively unexplored. Herein we show that high glucose concentration induces aberrant glycosylation, increased cell proliferation, invasion and tumor progression of colon cancer. By modulating the activity of the rate-limiting enzyme, glutamine-fructose-6-phosphate amidotransferase (GFAT), we demonstrate that hexosamine biosynthetic pathway (HBP) is involved in those processes. Biopsies from patients with colon carcinoma show increased levels of GFAT and consequently aberrant glycans' expression suggesting an increase of HBP flow in human colon cancer. All together, our results open the possibility that HBP links hyperglycemia, aberrant glycosylation and tumor malignancy, and suggest this pathway as a potential therapeutic target for colorectal cancer.

Characterization of novel structures of mannosylinositolphosphorylceramides from the yeast forms of Sporothrix schenckii.

Novel structures of glycoinositolphosphorylceramide (GIPC) from the infective yeast form of Sporothrix schenckii were determined by methylation analysis, mass spectrometry and NMR spectroscopy. The lipid portion was characterized as a ceramide composed of C-18 phytosphingosine N-acylated by either 2-hydroxylignoceric acid (80%), lignoceric (15%) or 2,3-dihydroxylignoceric acids (5%). The ceramide was linked through a phosphodiester to myo-inositol (Ins) which is substituted on position O-6 by an oligomannose chain. GIPC-derived Ins oligomannosides were liberated by ammonolysis and characterized as: Manpalpha1-->6Ins; Manpalpha1-->3Manpalpha1-->6Ins; Manpalpha1-->6Manpalpha1-->3Manpalpha1-->3Manpalpha1-->6Ins; Manpalpha1-->2Manpalpha1-->6Manpalpha1-->3Manpalpha1-->3Manpalpha1-->6Ins. These structures comprise a novel family of fungal GIPC, as they contain the Manpalpha1-->6Ins substructure, which has not previously been characterized unambigously, and may be acylated with a 2,3 dihydroxylignoceric fatty acid, a feature hitherto undescribed in fungal lipids.

Structure of an acidic exopolysaccharide produced by the diazotrophic endophytic bacterium Burkholderia brasiliensis.

The structure of an exopolysaccharide (EPS) produced by Burkholderia brasiliensis, a diazotrophic endophytic organism originally isolated from rice roots, has been determined. The bacterium was grown in a synthetic medium, containing mannitol and glutamate, which favours the expression of two anionic EPSs, which were separated by anion-exchange chromatography. The structure of the repeat unit of EPS A, eluted at higher ionic strength, was determined by a combination of methylation analysis, partial hydrolysis, chemical degradations, and NMR spectroscopic studies, and shown to be the linear O-acetylated pentasaccharide: -->4)-alpha-D-Glcp-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GlcpA-(1-->3)-beta-L-Rhap[2OAc]-(1-->4)-beta-D-Glcp-(1-->.

Ether--lipid (alkyl-phospholipid) metabolism and the mechanism of action of ether--lipid analogues in Leishmania.

Ether-lipid (alkyl-phospholipid) analogues such as Miltefosine possess potent in vitro and in vivo anti-leishmanial activity and these compounds are currently undergoing clinical trials in humans. These analogues are also effective against Trypanosoma cruzi and Trypanosoma brucei subspecies but their mode of action is not known. Leishmania have high levels of ether-lipids and these are mainly found in the glycosylphosphatidylinositol-anchored glycolipids and glycoproteins present on the surface of the parasites. In Leishmania mexicana promastigotes we have studied both the initiating steps for the biosynthesis of ether-lipids, and key remodelling steps. The effect of Miltefosine and Edelfosine, on key enzymes involved in the metabolism of ether-lipids has been studied. The enzymes include dihydroxyacetonephosphate acyltransferase, sn-l-acyl-2-lyso-glycero-3-phosphocholine and sn-l-alkyl-2-lyso-glycero-3-phosphocholine acyltransferases. We confirm that the initiating steps in ether-lipid metabolism in Leishmania are present in glycosomes, and that Miltefosine or Edelfosine did not perturb these enzymes. The metabolism of the latter phosphatidylcholine base intermediates, which may be involved in the remodelling of acyl- and alkyl-glycerophospholipids, was also seemingly associated with glycosomes. Both Miltefosine and Edelfosine inhibited this microbody (glycosomal) located alkyl-specific-acyl-CoA acyltransferase in a dose-dependent manner with an inhibitory concentration of 50 microM. It is suggested therefore that a perturbation of ether-lipid remodelling could be responsible for the anti-leishmanial action of these drugs.

Localisation of a 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the mitochondrial matrix of Trypanosoma brucei procyclics.

Contrary to Leishmania spp. and Trypanosoma cruzi, Trypanosoma brucei bloodstream forms do not synthesise their own sterols but take these compounds in the form of cholesterol directly from the mammalian host. However, procyclic insect stages synthesise ergosterol rather than cholesterol. Here the sub-cellular localisation of the first committed enzyme of this pathway of isoprenoid synthesis 3-hydroxy-3-methylglutaryl-coenzyme A reductase in T. brucei procyclics (0.9 nmol x min(-1) x mg(-1) protein) was carried out using both cell-fractionation by isopycnic centrifugation and digitonin-titration experiments. The majority of the NADP+-linked 3-hydroxy-3-methylglutaryl-coenzyme A reductase is a soluble enzyme present in the mitochondrial matrix with some additional membrane-associated activity in glycosomes and possibly in the endoplasmic reticulum. It is suggested that the active metabolism of threonine and/or leucine as preferred 2-carbon source for the incorporation of acetyl units into lipids and/or sterols in the mitochondrion of T. brucei procyclics is the explanation for a high 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in these protozoan organelles.

Incidence of intimal proliferation and apoptosis following balloon angioplasty in an atherosclerotic rabbit model.

OBJECTIVE: The aim of this study was to determine the occurrence of apoptosis in relation to the proliferative response in the intimal layer after experimental balloon angioplasty of a pre-existing plaque. METHODS: After induction of an intimal plaque in the right carotid artery by electrical stimulation, 26 rabbits underwent balloon angioplasty. Twelve animals served as a control group without performance of angioplasty after plaque induction. To study the time course of intimal apoptosis and cell proliferation the vessels were excised on day 7, 14 and 28 after balloon angioplasty. For in situ detection of apoptosis, the TUNEL-technique (TdT-mediated d-UTP fluorescein nick end labeling) was used. In addition, bromodeoxyuridine labeling in all animals allowed the determination of the percentage of cells undergoing DNA synthesis in the neointimal area. Additionally, smooth muscle cells were detected by immunostaining of alpha-actin and macrophages by a specific antibody (RAM 11). RESULTS: Within 28 days of balloon angioplasty, the number of cells undergoing apoptosis remained at a very low level and was not significantly different to the control group without interventional treatment (controls: 0.1 +/- 0.15%; 7 days: 0.44 +/- 0.68%; 14 days: 0.13 +/- 0.11%; 28 days: 0.1 +/- 0.1%). In contrast, the number of cells undergoing DNA synthesis was significantly increased at day 7 after angioplasty (3.72 +/- 2.0% vs. 0.51 +/- 0.29% in controls), resulting in an increase of the total intimal area from 0.088 +/- 0.037 mm2 in the control animals up to 0.256 +/- 0.172 mm2 at day 28 following balloon dilatation. CONCLUSIONS: Our data showed that significant changes in the occurrence of apoptosis are not involved in the regulation of cellular turnover during the examined time period after vessel wall injury. The lacking up-regulation of apoptosis in comparison to the increased cell proliferation in order to maintain the tissue balance is perhaps an important regulatory mechanism leading to intimal hyperplasia after vascular injury in this animal model. Overall, we suggest that there may be a delicate balance between cell proliferation and apoptosis in smooth muscle cells of the vessel wall, and only small shifts in this balance could account for both cellular accumulation in restenotic lesions as well as cell death in mature atheroma.

Purification, localisation and characterisation of glucose-6-phosphate dehydrogenase of Trypanosoma brucei.

Cell-fractionation and digitonin titration of procyclic trypomastigotes of Trypanosoma brucei, revealed that almost half of the total NADP+ -dependent glucose-6-phosphate dehydrogenase (G6PDH) activity, the first enzyme of the pentose phosphate pathway (PPP), is associated with glycosomes. The specific activity of G6PDH in the purified organelles was increased 4-fold relative to a total cell extract and showed latency. Moreover, in the absence of detergents this activity was totally resistant to the action of trypsin. The cytosolic counterpart was neither latent, nor was it resistant to trypsin. Both cytosolic and glycosomal G6PDH activities behaved identically on phenyl-, CM-, heparin-, and Affigel-blue-Sepharose columns. Both isoenzymes had a subunit Mr of 62 000 and an isoelectric point of 6.85, while kinetic studies carried out on the partially purified G6PDH from both cell compartments did not reveal any differences. The purified enzyme had an apparent Km of 138 and 5.3 microM for glucose 6-phosphate (G6P), and for NADP+, respectively, and had a specific activity of 14 micromol. (min mg of protein)(-1). We conclude that while in procyclic stages of T. brucei G6PDH activity is present in two different cell compartments, i.e. the cytosol and the glycosomes, these two activities most likely represent one and the same isoenzyme.

Lipid altering or antioxidant vitamins for patients with coronary disease and very low HDL cholesterol? The HDL-Atherosclerosis Treatment Study Design.

Evidence supports the idea that substantial benefits may derive from treatments that increase high density lipoprotein (HDL) cholesterol (HDL-C), apolipoprotein (apo) A-I, HDL2 (or 2b) or the size of HDL particles with, or without, apo A-II. HDL3 appears to be neutral in terms of coronary artery disease risk, and apo A-II appears to be adverse. Because HDL particles serve as antioxidants in vitro, the hypothesis that low HDL-C reflects an antioxidant deficiency state appears tenable. Based on these observations, a three-year angiographic study was proposed and received funding. Enrollment began in January 1995 and was completed in January 1997.

Effect of the antioxidant Nicanartine on the proliferative and inflammatory response after experimental balloon angioplasty.

BACKGROUND: Antioxidant treatment seems to reduce the development of restenosis after percutaneous transluminal angioplasty. In this study, the effect of Nicanartine, a new antioxidant drug with both antiproliferative and lipid-lowering properties, on the proliferative and inflammatory response after balloon angioplasty was investigated in a rabbit model of restenosis. METHODS: To induce pre-interventional plaques in the common carotid artery of 48 New Zealand White rabbits, electrostimulation was carried out for 28 days. After a break of 7 days, balloon angioplasty was performed in 36 animals, of which 18 received Nicanartine at a dose of 120 mg/kg body weight; the other 18 served as a control group. The vessels were excised by day 7 and 28 after balloon angioplasty and examined for intimal plaque size, macrophage content and proliferative activity. Bromodeoxyuridine labeling was used to determine proliferating cells in the dilated segment; macrophages were detected using the RAM-11 antibody. RESULTS: In the Nicanartine-treated group, immunohistological quantification 7 days after intervention showed a statistically significant (P< 0.05) reduction of both cells undergoing DNA synthesis (1.6+/-1.4% versus 3.7+/-2.2%) and intimal macrophages (0.7+/-1.2% versus 1.3+/-0.6%). Twenty-eight days after balloon angioplasty, proliferative activity in both groups was decreased to a level comparable to the non-dilated control groups. A clear trend towards smaller plaques could be seen in the Nicanartine group (0.146+/-0.077 mm2 versus 0.255+/-0.174 mm2). Total cholesterol levels did not differ significantly between the groups. CONCLUSION: Under treatment with Nicanartine a clear reduction in the proliferative and inflammatory response after balloon angioplasty was observed. Antioxidant treatment, especially with compounds having antiproliferative and lipid-lowering properties, appears to be an effective secondary preventive strategy after interventional treatment in patients with coronary artery disease.

The dihydroxyacetonephosphate pathway for biosynthesis of ether lipids in Leishmania mexicana promastigotes.

Biosynthetic studies using both [14C]- and [32P]-labelled substrates and a cell-free system to synthesise 1-O-alkyl moieties in glycerolipids, have shown that the three initial steps in ether-lipid biosynthesis in Leishmania mexicana promastigotes resemble those described for mammals and are associated with glycosomes. Purified glycosomes were able to sequentially synthesise the first intermediates of the ether-lipid biosynthetic pathway [acyl-dihydroxyacetonephosphate (DHAP), alkyl-DHAP and acyl/alkyl-glycerol-3-phosphate (G3P)] when incubated in the presence of radiolabelled DHAP, palmitoyl-CoA, hexadecanol and NADPH. However, when glycosomes were incubated under the same conditions in the presence of radiolabelled G3P, a rapid synthesis of acyl-G3P and phosphatidic acid was observed without any formation of alkyl-G3P, suggesting that the enzyme alkyl-synthase recognises only acyl-DHAP as substrate. Both the DHAP acyltransferase (DHAP-AT) and alkyl-DHAP synthase activities were located inside glycosomes whereas the alkyl/acyl-DHAP oxidoreductase activity was associated with the cytoplasmic face of the glycosomal membrane. The G3P acyltransferase (G3P-AT) and lyso-phosphatidic acid acyltransferase activities were not found inside glycosomes. The results suggest that the DHAP-AT and G3P-AT activities are catalysed by two distinct enzymes associated with different sub-cellular compartments.

Identification of complete precursors for the glycosylphosphatidylinositol protein anchors of Trypanosoma cruzi.

The survival of Trypanosoma cruzi, the causative agent of Chagas' disease, depends vitally on proteins and glycoconjugates that mediate the parasite/host interaction. Since most of these molecules are attached to the membrane by glycosylphosphatidylinositol (GPI), alternative means of chemotherapeutic intervention might emerge from GPI biosynthesis studies. The structure of the major 1G7 antigen GPI has been fully characterized by us (Güther, M. L. S., Cardoso de Almeida, M. L., Yoshida, N., and Ferguson, M. A. J.(1992) J. Biol. Chem. 267, 6820-6828; Heise, N., Cardoso de Almeida, M. L., and Ferguson, M. A. J.(1995) Mol. Biochem. Parasitol. 70, 71-84), and based on its properties we now report the complete precursor glycolipids predicted to be transferred to the nascent protein. Migrating closely to Trypanosoma brucei glycolipid A on TLC, such species, named glycolipids A-like 1 and A-like 2, were labeled with tritiated palmitic acid, myo-inositol, glucosamine, and mannose, but surprisingly only the less polar glycolipid A-like 1 incorporated ethanolamine. The predicted products following nitrous acid deamination and digestion with phospholipases A2, C, and D confirmed their GPI nature. Evidence that they may represent the anchor transferred to the 1G7 antigen came from the following analyses: (i) alpha-mannosidase treatments indicated that only one mannose was amenable to removal; (ii) their lipid moiety was identified as sn-1-alkyl-2-acylglycerol due to their sensitivity to phospholipase A2 (PLA2), mild base and by direct high performance TLC analysis of the corresponding benzoylated diradylglycerol components; and (iii) both glycolipids incorporated 3H-fatty acid only in the sn-2- and not in the sn-1-alkyl position as previously found in the GPI of the mature 1G7 antigen. Based on the differential [3H]ethanolamine incorporation pattern and the recent report that an aminoethylphosphonic acid (AEP) replaces ethanolamine phosphate (EtNH2-PO4) in the GPI in epimastigote sialoglycoproteins (Previato, J. O., Jones, C., Xavier, M. T., Wait, R., Travassos, L. R., Parodi, A. J., and Mendonça-Previato, L.(1995) J. Biol. Chem. 270, 7241-7250) it is proposed that glycolipid A-like 2 contains AEP and A-like 1 EtNH2-PO4. In the in vitro cell-free system both glycolipids were synthesized simultaneously and do not seem to bear a precursor/product relationship. Among the various components synthesized in vitro a glycolipid C-like corresponding to a form of glycolipid A-like 1 acylated on the inositol was also characterized. Phenylmethylsulfonyl fluoride, an inhibitor known to block the addition of ethanolamine phosphate in T. brucei but not in mammalian cells, also inhibits the synthesis of glycolipids A-like and C-like in T. cruzi, indicating that the putative trypanosome EtNH2-PO4/AEP transferase(s) might represent a potential target for chemotherapy.

Paracoccidioides brasiliensis expresses both glycosylphosphatidylinositol-anchored proteins and a potent phospholipase C.

This study reports, for the first time, the detection of glycosylphosphatidylinositol (GPI) membrane anchors in proteins of a pathogenic fungus, Paracoccidioides brasiliensis. Taking into account that fungal antigens are found in the sera of paracoccidioidiomycosis patients and that cleavage of this glycolipid by phospholipases is a means of selective protein release, the presence of an enzyme with this property has also been investigated. Using a methodological approach in which the proteins were immobilized on nitrocellulose, treated with phospholipase C of Trypanosoma brucei and then probed with antibodies which recognize the 1,2-cyclic-phosphate inositol moiety formed as a reaction product in proteins bearing the glycolipid anchor, it was possible to detect a major glycoprotein in the 80- to 90-kDa range, as well as two other minor species of 66 and 43 kDa. All of them bind to Concanavalin-A and are also substrates of a very potent fungal phospholipase C which is inhibited by p-chloromercuri-phenylsulfonic acid and is insensitive to EDTA. The integrity of glycosylphosphatidylinositol anchors in proteins of P. brasiliensis is impaired by 0.1 M NaOH, a finding indicative of a diacyl glycerolipid moiety which is quite surprising since it is, with the exception of African trypanosomes surface proteins and Torpedo acetylcholinesterase, an uncommon feature among GPIs in general. The present findings may have implications in the pathology of paracoccidiodomycosis.

Characterization of the lipid moiety of the glycosylphosphatidylinositol anchor of Trypanosoma cruzi 1G7-antigen.

The 90-kDa stage-specific 1G7-antigen has been implicated in the invasion of host cells by the metacyclic forms of Trypanosoma cruzi. The antigen is attached to the plasma membrane via glycosylphosphatidylinositol, the partial structure of which was the first to be determined for a protein of this parasite. In this study, the complete structure of the lipid component of the anchor was determined by electrospray mass spectrometry, gas chromatography mass spectrometry, phospholipase sensitivity and high-performance thin-layer chromatography of the diaradylglycerol components after benzoylation. These analyses showed that the lipid moiety of 1G7-antigen is composed essentially of 1-O-hexadecyl-2-O-hexadecanoyl-phosphatidylinositol and 1-O-hexadecyl-2-O-octadecanoyl-phosphatidylinositol. The high sensitivity of the electrospray mass spectrometric analysis unexpectedly revealed the presence of a small proportion of putative inositol-phosphoceramide structures, and confirmed the absence of inositol-acylated species. An interesting finding was that the biosynthetic incorporation of [3H]palmitate labelled solely the acyl position, and not the 1-O-alkyl chain in the 1G7-antigen anchor.

Rabbit knee-joint meniscal proteoglycans.

A major proteoglycan (PG) in rabbit meniscal fibrocartilage was extracted with 4 M guanidine-HCl. It represented 63% of the total uronic acid originally present in the tissue. The non-extractable PG could be released by treating the guanidine HCl-extracted tissue with trypsin followed by alkaline hydrolysis. The glycosaminoglycan (GAG) chains from the non-extractable PGs are shown to be of a different type than the extractable forms since the relative amounts of chondroitin sulphate isomers differ from each other.

Characterization of a phospholipase C-resistant inositol containing glycolipid from Trypanosoma cruzi.

Since glycosylphosphatidylinositol is the most common form of attachment of proteins to membranes in T. cruzi, and that this parasite depends on surface-mediated interactions for survival within the vector and mammalian host, it is probable that a drug which interfers with the metabolism of glycosylphosphatidylinositol (GPI) could be successfully employed in chemotherapy. Over the last few years several groups have been characterizing this mode of attachment in T. cruzi and more recently we have been concentrating our efforts on the identification of candidate precursors for protein anchors in metacyclic trypomastigotes. Previously detected GPI heterogeneity regarding solubilization of a major stage-specific antigen (1G7-Ag) by phospholipase C led us to investigate whether biosynthetic precursors with similar properties could also be identified. Two glycolipid species whose migration properties resemble glycolipids A and C of T. brucei were amenable to biosynthetic radiolabelling with palmitic acid, inositol, ethanolamine, glucosamine and mannose. Following purification, these species were submitted to classical GPI diagnostic treatments. In both cases digestion with GPI-specific phospholipase D (GPIPLD) produced phospatidic acid and treatment with either mild base or phospholipase A2 (PLA2) produced free fatty acid, indicating an acylation at least at position 2 of the glycerol. The glycolipid A-like species proved to be susceptible to solubilization by PIPLC of B. thuringiensis and by GPIPLC of T. brucei and the glycolipid C-like material proved to be fully resistant to both lipases.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of a phospholipase C-resistant inositol containing glycolipid from Trypanosoma cruzi

Since glycosylphosphatidylinositol is the most common form of attachment of proteins to membranes in T. cruzi, and that this parasite depends on surface-mediated interactions for survival within the vector and mammalian host, it is probable that a drug which interfers with the metabolism of glycosylphosphatidylinositol (GPI) could be successfully employed in chemotherapy. Over the last few years several groups have been characterizing this mode of attachment in T. cruzi and more recently we have been concentrating our efforts on the identification of candidate precursors for protein anchors in metacyclic trypomastigotes. Previously detected GPI heterogeneity regarding solubilization of a major stage-specific antigen (1G7-Ag) by phospholipase C led us to investigate whether biosynthetic precursors with similar properties could also be identified. Two glycolipid species whose migration properties resemble glycolipids A and C of T. brucei were amenable to biosynthetic radiolabelling with palmitic acid, inositol, ethanolamine, glucosamine and mannose. Following purification, these species were submitted to classical GPI diagnostic treatments. In both cases digestion with GPI-specific phospholipase D (GPIPLD) produced phosphatidic acid and treatment with either mild base or phospholipase A2 (PLA2) produced free fatty acid, indicating an acylation at least at position 2 of the glycerol. The glycolipid A-like species proved to be susceptible to solubilization by PIPLC of B. thuriengiensis and by GPIPLC of T. brucei and the glycolipid C-like material proved to be fully resistant to both lipases. Although the glycolipid A-like species indeed presents these and other properties compatible with a precursor for the chemically characterized 1G7-Ag anchor, the PLC-resistant species which is completely insensitive to nitrous acid deamination might be an exception to the general finding of a non-acetylated glucosamine in the GPI moieties so far described

Mucin-like glycoproteins linked to the membrane by glycosylphosphatidylinositol anchor are the major acceptors of sialic acid in a reaction catalyzed by trans-sialidase in metacyclic forms of Trypanosoma cruzi.

We have previously shown that 35- and 50-kDa glycoconjugates of cultured metacyclic trypomastigotes participate in the attachment of parasites to mammalian cells. Here we show that when metacyclic trypomastigotes are incubated with [3H]sialyllactose, most of the sialic acid is transferred to these 35/50-kDa molecules in a reaction catalyzed by a parasite transsialidase. The sialic acid is incorporated in oligosaccharides of about 10 glucose units in size that are released from the glycoconjugate by mild alkaline hydrolysis. Compositional analysis reveals that the 35/50-kDa molecules are highly glycosylated proteins rich in threonine, galactose, N-acetyl-glucosamine and sialic acid. These glycoproteins can be labeled in vivo with [3H]palmitate, and the labeled fatty acid is released by glycosylphosphatidylinositol specific phospholipases C. This result, associated with the fact that they contain mannose, ethanolamine, myo-inositol, and lipid, indicate that these glycoproteins are anchored to the membrane by glycosylphosphatidylinositol. During cell invasion, these molecules appear to be capped and locally released by the parasite.

Age-related changes in glycosaminoglycan distribution in different anatomical sites on the surface of knee-joint articular cartilage in young rabbits.

In spite of the fact that the various anatomical regions of a given articular cartilage surface are subjected to different degrees of stress, the present observations strongly suggest that there exists a topographical homogeneity in the distribution of glycosaminoglycans in the same articular cartilage. In contrast to this age-related changes in the proportion of the different types of glycosaminoglycan species in articular cartilage are remarkable. Non-sulphated chondroitin could only be detected in very young articular cartilage. Dermatan sulphate, which has already been detected in young adult rabbits, was followed by the appearance of keratan sulphate in older rabbits. Chondroitin 4-6-sulphates were detected in all articular cartilages studied, the proportion of the 6-sulphated variably increasing with age. The present report suggests that the distribution of glycosaminoglycans in articular cartilage varies with species and age, and the data can further vary, depending on the methods used. It is therefore concluded that generalizations against the results reported in the literature should be considered skeptically.

Proteins anchored via glycosylphosphatidylinositol and solubilizing phospholipases in Trypanosoma cruzi.

The presence of GPI anchors and phospholipases capable of solubilizing them in Trypanosoma cruzi has been investigated in epimastigotes, metacyclic trypomastigotes from axenic cultures and tissue culture trypomastigotes. The GPI anchored proteins in epimastigote forms are scarce when compared to their abundance in the parasite forms which can infect mammals, and GPI-solubilizing phospholipases C have been found in all life cycles stages. In epimastigote and metacyclic forms, the activity is found in the soluble fraction upon cell lysis, whereas in tissue cultured trypomastigotes it is membrane bound and, being mostly sensitive to p-chloromercuriphenylsulfonate, resembles closely the GPI specific phospholipase of Trypanosoma brucei. Sequential immunoprecipitations with monoclonal antibodies and anti-CRD indicated the presence of several sub-populations among the surface proteins of metacyclic trypomastigotes, five of these belonging to the GPI-anchored 90 kD family. Among this family, the epitopes recognized by MAb-1G7 are present in three members, one of them also expressing the 3F6 epitope. There are 2 members recognized only by MAb-3F6 but not by MAb-1G7, one of them being probably galactosylated on the GPI since it can be immunoprecipitated by anti-CRD. Very strangely, the epitope recognized by the MAb-WIC29.26 was always present on the gp72, as originally described, but under certain circumstances appeared cryptic on one of the 90 kD species. During epimastigote transformation into metacyclic trypomastigotes in vitro, the ability of the GPI of the 1G7-antigen to be solubilized by phospholipase C and D varies depending on the age of the culture and presence or absence of fetal calf serum. Different patterns of solubilization were also obtained for 1G7-Ag, depending on whether the test is performed with parasite lysates or with antigen affinity purified from them. Our data indicate that the phospholipase C resistance observed does not arise from acylation on the inositol, as previously described for acetylcholinesterase from human erythrocytes, being rather due to factors which either modify the GPI or affect the action of the phospholipases. Previously unreported resistance to glycosylphosphatidylinositol-specific phospholipase D has been observed both to glycosylphosphatidylinositol-specific phospholipase D has been observed both to 1G7-Ag and 10D8-Ag, the GPI-anchored mucynlike protein which is acceptor of sialic acid in metacyclic forms. Our findings are discussed in the light of the presently known structures of GPI in this parasite, and imaginative speculation on biological roles for the GPI phospholipase system in T. cruzi is also provided.