Antibody-based assay for N-deacetylase activity of heparan sulfate/heparin N-deacetylase/N-sulfotransferase (NDST): novel characteristics of NDST-1 and -2

A new assay was developed to measure the N-deacetylase activity of the glucosaminyl N-deacetylase/N-sulfotransferases (NDSTs), which are key enzymes in sulfation of heparan sulfate (HS)/heparin. The assay is based on the recognition of NDST-generated N-unsubstituted glucosamine units in Escherichia coli K5 capsular polysaccharide or in HSs by monoclonal antibody JM-403. Substrate specificity and potential product inhibition of the NDST isoforms 1 and 2 were analyzed by comparing lysates of human 293 kidney cells stably transfected with mouse NDST-1 or -2. We found HSs to be excellent substrates for both NDST enzymes. Both NDST-1 and -2 N-deacetylate heparan sulfate from human aorta ( approximately 0.6 sulfate groups/disaccharide) with comparable high efficiency, apparent Km values of 0.35 and 0.76 microM (calculation based on [HexA]) being lower (representing a higher affinity) than those for K5 polysaccharide (13.3 and 4.7 microM, respectively). Comparison of various HS preparations and the unsulfated K5 polysaccharide as substrates indicate that both NDST-1 and -2 can differentially N-sulfate polysaccharides already modified to some extent by various other enzymes involved in HS/heparin synthesis. Both enzymes were equally inhibited by N-sulfated sequences (>or=6 sugar residues) present in N-sulfated K5, N-deacetylated N-resulfated HS, and heparin. Our primary findings were confirmed in the conventional N-deacetylase assay measuring the release of 3H-acetate of radiolabeled K5 or HS as substrates. We furthermore showed that NDST N-deacetylase activity in crude cell/tissue lysates can be partially blocked by endogenous HS/heparin. We speculate that in HS biosynthesis, some NDST variants initiate HS modification/sulfation reactions, whereas other (or the same) NDST isoforms later on fill in or extend already modified HS sequences.

Somatic hypermutation and V(H) gene usage in mantle cell lymphoma

Mantle cell lymphoma (MCL) is considered to derive from naïve, pregerminal center (GC) CD5+ B-cells. However, the cell of origin has been questioned in recent studies that showed somatic hypermutations in the immunoglobulin (Ig) variable heavy chain (V(H)) genes in subsets of MCL. To clarify this issue, we analyzed the IgV(H) genes for the presence of somatic hypermutations in 51 MCL cases. Twenty percent of the MCL cases displayed somatically mutated V(H) genes (defined as >2% mutated), whereas 80% showed unmutated V(H) genes. This finding suggests that MCL is a genetically heterogeneous disease, with the majority of cases originating from unmutated pre-GC B-cells and a subset deriving from more mature B-cells which have been exposed to the GC environment and have undergone somatic hypermutation. A biased V(H) gene usage has been demonstrated in several B-cell malignancies; however, this has not yet been investigated in MCL, although V(H)4-34 overusage has been indicated by small studies. Interestingly, we found a restricted usage of three individual V(H) genes in our MCL material; V(H)4-34 (22%), V(H)3-21 (16%) and V(H)5-51 (12%). This novel finding of preferential V(H) gene usage in half of the MCL cases may suggest an antigen driven process occurring in B-cells expressing specific VH genes, thus implicating that Ig specificity could be involved in mantle cell lymphoma development.

Self-rated health. Comparisons between three different measures. Results from a population study

BACKGROUND

Self-rating of health is among the most frequently assessed health perceptions in epidemiological research. The aim of this study was to compare different measures of global self-rated health (SRH) with respect to differences in age and sex groups and relations to hypothesized determinants.

METHOD

Three single-question measures of SRH were included in a health questionnaire administered to 8200 randomly chosen men and women. Two SRH measures were non-comparative, one with seven (SRH-7) and one with five response options (SRH-5), while the third measure included a comparison with others of the same age (SRH-age). SRH-7 had specified response options only at the ends of the scale, while the other two measures gave specified statements for each option. Comparisons between the SRH assessments were studied with respect to response frequencies, frequency distributions, age and gender differences and differences in associations with hypothesized determinants.

RESULTS

The differences between the SRH measures were in most cases marginal. Some diversities may, however, be worth considering: a high drop-out rate for the SRH-7 measure in the oldest age group; a trend that SRH-7 correlated most strongly with the independent variables; SRH-age showed improved health ratings with increasing age but a less skewed frequency distribution compared to the non-comparative measures.

CONCLUSIONS

The results imply that non-comparative measures are more appropriate in longitudinal studies and that measures without specified response options might be less suitable for an older study group. The overall impression is, however, that the different measures represents parallel assessments of subjective health.

Gastric cancer and human leukocyte antigen: distinct DQ and DR alleles are associated with development of gastric cancer and infection by Helicobacter pylori

DNA and sera from 130 cases of gastric cancer and 263 population-based controls were analyzed to study the association of HLA class II DR-DQ alleles with Helicobacter pylori (Hp) infection and the risk for gastric cancer. Presence of the DQA1*0102 allele was inversely and significantly associated with Hp seropositivity (P = 2 x 10(-5)), which is an independent replication of previous findings. However, this inverse relationship with Hp did not correspond with a reduced risk of gastric cancer. At the DRB1 locus, the *1601 allele was significantly associated with an increased gastric cancer risk with an odds ratio (95% confidence interval) of 8.7 (range, 2.7-28.0). The effect of *1601 was more pronounced among Hp-negative subjects, and the association was stronger with the diffuse, rather than with the intestinal, histological type of gastric cancer. Because none of the HLA alleles were associated with both Hp infection and gastric cancer, the HLA DR-DQ alleles are linked with gastric cancer risk through other mechanisms than an increased susceptibility to Hp infection.

Defective heparan sulfate biosynthesis and neonatal lethality in mice lacking N-deacetylase/N-sulfotransferase-1

Heparan sulfate is a sulfated polysaccharide present on most cell surfaces and in the extracellular matrix. In vivo functions of heparan sulfate can be studied in mouse strains lacking enzymes involved in the biosynthesis of heparan sulfate. Glucosaminyl N-deacetylase/N-sulfotransferase (NDST) catalyzes the first modifying step in the biosynthesis of the polysaccharide. This bifunctional enzyme occurs in several isoforms. We here report that targeted gene disruption of NDST-1 in the mouse results in a structural alteration of heparan sulfate in most basement membranes as revealed by immunohistochemical staining of fetal tissue sections using antibodies raised against heparan sulfate. Biochemical analysis of heparan sulfate purified from fibroblast cultures, lung, and liver of NDST-1-deficient embryos demonstrated a dramatic reduction in N-sulfate content. Most NDST-1-deficient embryos survive until birth; however, they turn out to be cyanotic and die neonatally in a condition resembling respiratory distress syndrome. In addition, a minor proportion of NDST-1-deficient embryos die during the embryonic period. The cause of the embryonic lethality is still obscure, but incompletely penetrant defects of the skull and the eyes have been observed.

Overexpression of different isoforms of glucosaminyl N-deacetylase/N-sulfotransferase results in distinct heparan sulfate N-sulfation patterns

Functional interactions of heparan sulfate (HS) with selected proteins depend on distinct saccharide sequences which are generated during biosynthesis of the polysaccharide. Glucosaminyl N-deacetylase/N-sulfotransferases (NDSTs) catalyze both the N-deacetylation and N-sulfation reactions that initiate the modification of the (GlcNAc-GlcA)(n) polysaccharide backbone. The N-acetyl/N-sulfate exchange is restricted to certain regions of the polysaccharide chains, and only these can be further modified by glucuronyl C5-epimerization and O-sulfation at various positions. To investigate whether NDST isoforms influenced differently the structure of HS, murine NDST-1 was overexpressed in human kidney 293 cells, and the structure of the HS produced was compared to HS from NDST-2 overexpressing cells [Cheung, W. F., Eriksson, I., Kusche-Gullberg M., Lindahl, U., and Kjellén, L. (1996) Biochemistry 35, 5250-5256]. The level of N-sulfation increased from 40% in control cells to 60% and 80%, respectively, in NDST-1 and NDST-2 transfected cells. Interestingly, the increase in N-sulfation was accompanied by an increased chain length, while no effect on IdoA content or O-sulfation was seen. The most extended N-sulfated domains were found in HS synthesized by NDST-2 transfected cells. Since both the N-deacetylase and the N-sulfotransferase activities were lower in these cells than in the NDST-1 overexpressing cells, we conclude that, in addition to the level of enzyme expression, the NDST isoform also is important in determining the N-sulfation pattern in HS.

Minimally invasive treatment of infection staghorn stones with shock wave lithotripsy and chemolysis

We report the results in 118 patients with infection staghorn stones treated with an anaesthesia-free minimally invasive method that combined repeated shock-wave lithotripsy (SWL) sessions (unmodified Dornier HM3 lithotripter) and percutaneous chemolysis with Renacidin. The stone-free rate was 60%. In 27 consecutive patients with infection staghorn stones representative of patients with this stone type in the population, a stone-free rate of 77% was recorded. The latter figure is comparable with results reported for open surgery, percutaneous surgery and sandwich therapy, and superior to that recorded with SWL alone. During the study period, no patient referred to us with an infection staghorn stone was treated with percutaneous, ureteroscopic or open surgery, and all treatments were carried out without regional or general anaesthesia. The described treatment concept had a very low complication rate, but required a fairly long hospital stay, with a mean of 32 days (range: 5-82). The long period necessary for completing the treatment in the most complicated cases might render the procedure less attractive as a standard method, but it is nevertheless an excellent option in high-risk patients and in all those patients in whom other procedures are impossible.

Abnormal mast cells in mice deficient in a heparin-synthesizing enzyme

Heparin is a sulphated polysaccharide, synthesized exclusively by connective-tissue-type mast cells and stored in the secretory granules in complex with histamine and various mast-cell proteases. Although heparin has long been used as an antithrombotic drug, endogenous heparin is not present in the blood, so it cannot have a physiological role in regulating blood coagulation. The biosynthesis of heparin involves a series of enzymatic reactions, including sulphation at various positions. The initial modification step, catalysed by the enzyme glucosaminyl N-deacetylase/N-sulphotransferase-2, NDST-2, is essential for the subsequent reactions. Here we report that mice carrying a targeted disruption of the gene encoding NDST-2 are unable to synthesize sulphated heparin. These NDST-2-deficient mice are viable and fertile but have fewer connective-tissue-type mast cells; these cells have an altered morphology and contain severely reduced amounts of histamine and mast-cell proteases. Our results indicate that one site of physiological action for heparin could be inside connective-tissue-type mast cells, where its absence results in severe defects in the secretory granules.

High resolution genetic typing of the class II HLA-DRB1 locus using group-specific amplification and SSO-hybridisation in microplates

The HLA-DRB1 locus is one of the most polymorphic HLA class II loci and rapid and accurate typing of this polymorphism is important both in bone-marrow transplantation, analysis of disease association and in forensic medicine. The allelic variation at DRB1 is characterized by combinations of a limited number of amino-acid motifs, reducing the resolution of a typing strategy based on a single PCR and subsequent analysis of polymorphic motifs. In the present paper we describe a strategy for typing of DRB1 based on eight allele-specific PCRs followed by sandwich hybridization to immobilized probes in a microplate format. The combined approach results in a rapid typing system with very high resolution. Using a rapid DNA extraction protocol, a complete HLA-DRB1 typing can be performed in less than a day.

An experimental head restraint concept for primary prevention of head and neck injuries in frontal collisions

The Experimental Head Restraint Concept (EHRC), a 'safety belt' for the head, is designed to reduce forces to the head and neck, in frontal car crashes. The EHRC was evaluated experimentally in frontal collision for a crash severity of 11 m/s, and numerically in frontal collision for a crash severity of 11 and 15 m/s. Experimental data obtained from a frontal barrier test (11 m/s) showed a 67% reduction of the HIC value from 411 (without EHRC) to 136 (with EHRC). The same level of reduction was also obtained for the higher speed in the numerical simulation. The moment in the neck was shown in experimental configuration to increase a few percent using the EHRC, but as presented in a numerical analysis, the moment was reduced by stiffening the EHRC. The EHRC clearly has a potential role in the search for primary prevention of neurotrauma injuries in frontal related car crashes. However, there is a strong need for more advanced injury criteria for the neck in order to optimize such complex safety systems.

Identification and expression in mouse of two heparan sulfate glucosaminyl N-deacetylase/N-sulfotransferase genes

The biosynthesis of heparan sulfate/heparin is a complex process that requires the coordinate action of a number of different enzymes. In close connection with polymerization of the polysaccharide chain, the modification reactions are initiated by N-deacetylation followed by N-sulfation of N-acetylglucosamine units. These two reactions are carried out by a single protein. Proteins with such dual activities were first purified and cloned from rat liver and mouse mastocytoma. The mouse mastocytoma enzyme is encoded by an approximately 4-kilobase (kb) mRNA, whereas the rat liver transcript contains approximately 8 kb. In the present study, the primary structure of the enzyme encoded by the mouse 8-kb transcript is described. It is demonstrated that both the 4-and 8-kb transcripts have a wide tissue distribution and that they are encoded by separate genes. Characterization of the gene encoding the 4-kb transcript demonstrates that it spans a region of about 8 kb and that it contains at least 14 exons. The similarity of this gene and the previously characterized human gene for the 8-kb transcript is discussed.

Mitochondrial sequence variants in patients with schizophrenia

To investigate whether mitochondrial mutations underly susceptibility to schizophrenia, we sequenced the mtDNAs of two unrelated Swedish patients with schizophrenia and low cytochrome oxidase activity and two maternally related Scottish patients from a family with suspected maternal inheritance of the disease. We found five substitutions in coding regions that have not previously been described as polymorphisms. These new substitutions were studied in 81 schizophrenic patients and five control groups from Sweden and Scotland and found to differ in frequency between populations, emphasizing the importance of using large and well-defined control materials for evaluating the association of mtDNA mutations with disease. The results do not lend strong support to the association of a particular mtDNA substitution with increased risk for schizophrenia. However, the trend towards a higher frequency of substitutions in the patients deserves further attention.

Detection of serum interferon-alpha by dissociation-enhanced lanthanide fluoroimmunoassay. Studies of patients with acute viral and bacterial infections

A sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) was evaluated for ability to detect interferon-alpha (IFN-alpha) in serum of patients with acute infectious disease of less than one week's duration and a fever of > 38 degrees C. None of 36 patients with confirmed or probable bacterial disease was IFN-alpha positive. In contrast, 13/26 patients with viral infections had detectable levels of IFN-alpha in serum, all clearly positive (> or = 10 U/ml). The IFN-alpha positive serum samples were obtained early after onset of clinical disease, after a mean of 2.4 days. The IFN-alpha positive samples were obtained from 10 of the 12 patients with influenza or flu-like infection, and 3 of the 5 patients with varicella or herpes zoster. The IFN-alpha negative patients with viral disease (n = 9) included five patients with mononucleosis. The DELFIA should be useful in further studies of the value of IFN-alpha determinations in the identification of acute viral infections.

Mouse mastocytoma cells synthesize undersulfated heparin and chondroitin sulfate in the presence of brefeldin A

In order to study the subcellular localization and organization of the enzymes involved in the glycosylation of the hybrid proteoglycan serglycin, mouse mastocytoma cells were metabolically labeled with [35S]sulfate or [3H]glucosamine in the absence or presence of brefeldin A. This drug is known to induce a disassembly of the proximal part of the Golgi complex, resulting in a redistribution of cis-, medial-, and trans-Golgi resident enzymes back to the endoplasmic reticulum, and to block the anterograde transport of proteins to the trans-Golgi network. Although the total incorporation of [3H]glucosamine into glycosaminoglycan chains was reduced to about 25% in brefeldin A-treated cells compared to control cells, both control cells and cells treated with brefeldin A synthesized heparin as well as chondroitin sulfate chains. Therefore, enzymes involved in the biosynthesis of both types of glycosaminoglycan chains seem to be present proximal to the trans-Golgi network in these cells. Chondroitin sulfate and heparin synthesized in cells exposed to brefeldin A were undersulfated, as demonstrated by ion-exchange chromatography, compositional analyses of disaccharides, as well as by a lower [35S]sulfate/[3H]glucosamine ratio compared to controls. In heparin biosynthesis, both N- and O-sulfation reactions were impaired, with a larger relative decrease in 2-O-sulfation than in 6-O-sulfation. Despite undersulfation, the heparin chains synthesized in the presence of brefeldin A were larger (30 kDa) than the heparin synthesized by control cells (20 kDa). The reduced [3H]glucosamine incorporation in brefeldin A-treated cells was partly due to decreased number of glycosaminoglycan chains synthesized, but also to the biosynthesis of chondroitin sulfate chains of smaller molecular size (8 versus 15 kDa in control cells). Brefeldin A had no effect on the glycosaminoglycan synthesis when used in a cell-free, microsomal fraction, indicating that brefeldin A does not interfere directly with the enzymes involved in the biosynthesis of glycosaminoglycans.

Idiotype-specific T lymphocytes in monoclonal gammopathies: evidence for the presence of CD4+ and CD8+ subsets

Tumour-specific CD4+ T helper (Th) and CD8+ T cytotoxic (Tc) cells may participate in the control and eradication of tumour cells. In the present study, idiotype-specific stimulation of CD4+ and CD8+ blood T cells from patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma stage I was examined. Activation was measured in the CD4+ and CD8+ subsets enriched by magnetic microbeads as the incorporation of 3H-thymidine and the secretion of interferon (IFN)-gamma, interleukin (IL)-2 and IL-4 by single cells using the enzyme-linked immunospot assay. Idiotype-specific T cells were found in four of seven patients. Stimulation was mainly confined to the CD4+ subset in three of the four responding patients. This type of response was major histocompatibility complex (MHC) class II restricted as it could be inhibited by monoclonal antibodies against MHC class II (HLA-DR), but not against class I (HLA-ABC) molecules. Idiotype-specific CD8+ T cells were also demonstrated in these patients although at a lower frequency. One patient showed a strong and dominating activation of CD8+ T cells which could be blocked by antibodies against HLA-ABC but not against HLA-DR. Idiotype-specific CD4+ or CD8+ T cells were mainly of the type-1 subsets as judged by their secretion of IFN-gamma and IL-2. Thus, this study provides evidence for the presence of idiotype-specific and MHC-restricted CD4+ and CD8+ T cells of the type-1 subsets in patients with monoclonal gammopathies. Such T cells with the potential to control the growth of tumour B cells may be a suitable target for immunotherapeutic interventions in patients.

Human brain contains high levels of heteroplasmy in the noncoding regions of mitochondrial DNA

We have analyzed the level of intraindividual sequence variability (heteroplasmy) of mtDNA in human brain by denaturing gradient gel electrophoresis and sequencing. Single base substitutions, as well as insertions or deletions of single bases, were numerous in the noncoding control region (D-loop), and 35-45% of the molecules from a single tissue showed sequence differences. By contrast, heteroplasmy in coding regions was not detected. The lower level of heteroplasmy in the coding regions is indicative of selection against deleterious mutations. Similar levels of heteroplasmy were found in two brain regions from the same individual, while no heteroplasmy was detected in blood. Thus, heteroplasmy seems to be more frequent in nonmitotic tissues. We observed a 7.7-fold increase in the frequency of deletions/insertions and a 2.2-fold increase in the overall frequency of heteroplasmic mutations in two individuals aged 96 and 99, relative to an individual aged 28. Our results show that intraindividual sequence variability occurs at a high frequency in the noncoding regions of normal human brain and indicate that small insertions and deletions might accumulate with age at a lower rate than large rearrangements.

Composite polytetrafluroethylene/vein bypass grafts: conventional distal vein segment or vein cuff?

OBJECTIVES

To determine the current status of PTFE vein composite grafts, we reviewed our experience with 205 composite reconstructions and compared the results of conventional distal vein segment to that of distal vein cuff.

DESIGN

Retrospective review.

SETTING

Department of Surgery, University Hospital.

PATIENTS AND METHODS

The series included 85 women and 102 men with a median age of 70. The indications for surgery were claudication in 30, rest pain in 71 and ulcer/gangrene in 103. The site of the distal anastomosis was the popliteal artery in 111 and crural artery in 94. The graft consisted of a proximal PTFE graft anastomosed to a distal segment of reversed saphenous vein in 169 or to a modified distal Miller cuff in 36 operations after 1992.

RESULTS

Cumulative life table primary patency rates for the whole series at 12, 24 and 36 months were 39%, 32% and 25% respectively. Limbs with good run-off demonstrated significantly better patency rates compared to limbs with poor run-off (55% and 17% at 12 months, 35% and 11% at 36 months, p = 0.04). The patency rate of femorocrural grafts with poor run-off was only 4% at 12 months. The overall limb salvage rates at 12 and 36 months were 63% and 55%, respectively. Similar results were obtained in limbs with distal reversed vein segment and distal vein cuff.

CONCLUSION

The results of this study suggest that for infrainguinal bypass grafting where the saphenous vein is unavailable, a composite PTFE-vein graft might be an acceptable alternative in limbs with good run-off. Although not a randomised study, the results using a distal reversed vein segment of a cuff were similar.

Effects of terbuthylazine on soil fauna and decomposition processes

Acute lethal and sublethal effects of terbuthylazine and the commercial herbicide preparation Gardoprim [terbuthylazine is the active ingredient (a.i.)] on soil organisms (microbes, oppioid mites, two gamasid mite species, enchytraeids, and nematodes) were studied. In the humus soil terbuthylazine had no toxic effects on soil animals tested. However, the herbicide preparation had acute toxic effects on enchytraeids [no-observed-effect level (NOEL) 1.0 g a.i. /m2] and both gamasid mites (NOEL 2.4 and 5.0 g a.i./m2). According to filter paper test, the LC50 value for oppioid mites was 14.5 g a. i./m2. In the humus soil the commercial preparation caused no dose-related mortality in Oppioidea. The preparation was more toxic to gamasid mites when the herbicide was applied on the soil surface compared to the treatment in which the chemical was mixed into the humus. Application method of the chemical did not affect the mortality of enchytraeids. In the multispecies experiment, the number of nematodes was higher in the highest concentration of the commercial preparation (50 g a.i./m2) compared to the lowest concentration (1 g a.i./m2) and the clean soil. The amount of NH+4-N in the humus tended to increase with increasing herbicide concentration. The herbicide did not affect soil respiration, microbial biomass, or water content of the humus. These results indicated that herbicides can have direct effects on soil fauna. Due to species-specific foraging strategies or different exposure routes and rates to animals, effects of herbicides on soil animals varied considerably. Single-species toxicity tests performed in humus soil were more sensitive to the effects of herbicide than ecologically relatively short-term multispecies test.

Expression of the mouse mastocytoma glucosaminyl N-deacetylase/ N-sulfotransferase in human kidney 293 cells results in increased N-sulfation of heparan sulfate

The biosynthesis of heparin and heparan sulfate involves a series of polymer-modification reactions that is initiated by N-deacetylation and subsequent N-sulfation of N-acetylglucosamine residues. These reactions are catalysed by a combined N-deacetylase/N-sulfotransferase. Proteins expressing both activities have previously been purified from mouse mastocytoma, which generates heparin, and from rat liver, which produces heparan sulfate. In the present study, the mouse mastocytoma enzyme has been expressed in the human kidney cell line, 293, to investigate whether it could promote modification of the endogenous heparan sulfate precursor polysaccharide into a heparan-like molecule. The N-deacetylase activity of the stably transfected cell clones as approximately 8-fold higher, on a cell-protein basis, than that of control cells, while the N-sulfotransferase activity was increased approximately 2.5 fold. The amounts of glycosaminoglycans synthesized were the same in control and transfected cells, measured as incorporation of [3H]-glucosamine, whereas 35S-labeled glycosaminoglycans were approximately 50% increased in transfected cells, with an increased relative content of heparin sulfate. Structural analysis demonstrated the the glucosamine units of the "heparan sulfate" from transfected cells were almost exclusively N-sulfated, as expected for heparin, whereas more than half of the glucosamine units of the control polysaccharide remained N-acetylated. Notably, the increased N-sulfation was not accompanied by increased O-sulfation, not by C-5 epimerization of D-glucuronic to L-iduronic acid units. The implications of these findings are discussed with regard to the regulation of the biosynthetic process.

Structural features of an arabinan fragment isolated from the water-soluble fraction of dehulled rapeseed

A water-soluble polysaccharide fraction was prepared from dehulled rapeseed meal (winter rapeseed variety Casino). Further purification yielded two major fractions having a high content of arabinose and galactose residues, with Ara/Gal ratios of 5.4 (G1) and 1.8 (G2). The Ara/Gal ratio of the high molecular weight fraction G1 was stable over the whole gel filtration peak, indicating that the arabinose and galactose residues are part of the same polysaccharide. The high molecular weight fraction G1 was studied further by methylation analysis and several NMR techniques. Structural studies showed G1 to consist mainly of arabian fragments, which have terminal alpha-L-arabinofuranosyl groups with anomeric carbons bound (1-->5) (A) or (1-->2) (B), and 2,5-substituted arabinosyl residues with anomeric carbons bound (1-->5) (D) or (1-->2) (C) to adjacent arabinosyl residues. The A:B:C:D ratios were 2:1:1:1 according to results from NMR and methylation analysis.

Heparin proteoglycans synthesized by mouse mastocytoma contain chondroitin sulphate

Proteoglycans (PGs), biosynthetically labelled with [35S]sulphate, were isolated from mouse mastocytoma tissue. Chromatography on antithrombin (AT)-Sepharose resulted in the separation of the 35S-labelled PGs into three fractions: PGs with no affinity for the gel (NA-PGs), PGs with low affinity (LA-PGs), and PGs with high affinity (HA-PGs) for antithrombin. Whereas NA-PGs contained almost exclusively chondroitin sulphate (CS), the AT-binding PGs contained 80-85% heparin and 15-20% CS. [35S]CS-containing macromolecules obtained from the HA-PG fraction after removal of the heparin polysaccharide chains were rechromatographed on AT-Sepharose. A majority of these 35S-labelled macromolecules no longer showed affinity for AT. These experiments indicate that the [35S]CS recovered in the AT-binding PGs is present in hybrid PGs. Polysaccharide chain-length determination demonstrated that the heparin chains were somewhat larger (M(r) approximately 30,000) than the CS chains in the NA-PGs (M(r) approximately 25,000). CS chains in the hybrid PGs were slightly smaller (M(r) approximately 20,000). Characterization of the sulphated CS disaccharides from NA- and HA-PGs showed that they contained similar amounts (20%) of disulphated disaccharides of [GlcA-GalNAc(4,6-di-OSO3)] type. The monosulphated CS-disaccharides were O-sulphated at C-4 of the galactosamine units. Analysis by gel chromatography of the [35S]CS components isolated from HA-PGs after heparinase treatment showed that a major portion of these contained one CS chain only. Calculations of the number of CS and heparin chains in AT-binding PGs, based on polysaccharide composition and polysaccharide chain length, indicate that all heparin-containing PGs are hybrids.

Decreased cytochrome-c oxidase activity and lack of age-related accumulation of mitochondrial DNA deletions in the brains of schizophrenics

Defects in mitochondrial energy production have been implicated in several neurodegenerative disorders, such as Parkinson disease and amyotrophic lateral sclerosis. To study the contribution of mitochondrial defects to Alzheimer disease and schizophrenia, cytochrome-c oxidase (COX) activity and levels of the mtDNA4977 deletion in postmortem brain tissue specimens of patients were compared with those of asymptomatic age-matched controls. No difference in COX activity was observed between Alzheimer patients and controls in any of five brain regions investigated. In contrast, schizophrenic patients had a 63% reduction of the COX activity in the nucleus caudatus (P < 0.0001) and a 43% reduction in the cortex gyrus frontalis (P < 0.05) as compared to controls. The average levels of the mtDNA4977 deletion did not differ significantly between Alzheimer patients and controls, and the deletion followed similar modes of accumulation with age in the two groups. In contrast, no age-related accumulation of mtDNA deletions was found in schizophrenic patients. The reduction in COX activity in schizophrenic patients did not correlate with changes in the total amount of mtDNA or levels of the mtDNA4977 deletion. The lack of age-related accumulation of the mtDNA4977 deletion and reduction in COX activity suggest that a mitochondrial dysfunction may be involved in the pathogenesis of schizophrenia.