Specialized digestive mechanism for an insect-bacterium gut symbiosis

In Burkholderia-Riptortus symbiosis, the host bean bug Riptortus pedestris harbors Burkholderia symbionts in its symbiotic organ, M4 midgut, for use as a nutrient source. After occupying M4, excess Burkholderia symbionts are moved to the M4B region, wherein they are effectively digested and absorbed. Previous studies have shown that M4B has strong symbiont-specific antibacterial activity, which is not because of the expression of antimicrobial peptides but rather because of the expression of digestive enzymes, mainly cathepsin L protease. However, in this study, inhibition of cathepsin L activity did not reduce the bactericidal activity of M4B, indicating that there is an unknown digestive mechanism that renders specifically potent bactericidal activity against Burkholderia symbionts. Transmission electron microscopy revealed that the lumen of symbiotic M4B was filled with a fibrillar matter in contrast to the empty lumen of aposymbiotic M4B. Using chromatographic and electrophoretic analyses, we found that the bactericidal substances in M4B existed as high-molecular-weight (HMW) complexes that were resistant to protease degradation. The bactericidal HMW complexes were visualized on non-denaturing gels using protein- and polysaccharide-staining reagents, thereby indicating that the HMW complexes are composed of proteins and polysaccharides. Strongly stained M4B lumen with Periodic acid-Schiff (PAS) reagent in M4B paraffin sections confirmed HMW complexes with polysaccharide components. Furthermore, M4B smears stained with Periodic acid-Schiff revealed the presence of polysaccharide fibers. Therefore, we propose a key digestive mechanism of M4B: bacteriolytic fibers, polysaccharide fibers associated with digestive enzymes such as cathepsin L, specialized for Burkholderia symbionts in Riptortus gut symbiosis.

Danshen injection induces autophagy in podocytes to alleviate nephrotic syndrome via the PI3K/AKT/mTOR pathway

BACKGROUND

Danshen injection (DSI) is an agent extracted from the Salvia miltiorrhiza Bunge, a natural drug commonly used to alleviate kidney diseases. However, the material basis and therapeutic effects of DSI on nephrotic syndrome (NS) remain unclear.

PURPOSE

To investigate the material basis of DSI and the therapeutic effects and underlying mechanisms of NS.

METHODS

NS models were established using adriamycin-induced BALB/c mice and lipopolysaccharide-induced mouse podocytes (MPC-5). Following DSI and prednisone administration, kidney coefficients, 24 h urine protein, blood urea nitrogen, and serum creatinine levels were tested. Histomorphology was observed by periodic acid-Schiff staining and hematoxylin and eosin staining of the kidney sections. The glomerular basement membrane and autophagosomes of the kidneys were observed using transmission electron microscopy. Nephrin and desmin levels in the glomeruli were tested using immunohistochemistry. The viability of MPC-5 cells was tested using cell counting kit-8 after chloroquine and rapamycin administration in combination with DSI. The in vivo and in vitro protein levels of phosphatidylinositol 3-kinase (PI3K), AKT, phosphorylated AKT (Ser473), mammalian target of rapamycin (mTOR), microtubule-associated protein light chain 3 (LC3), beclin1, cleaved caspase-3, and caspase-3 were detected using western blotting.

RESULTS

Our results showed that DSI contained nine main components: caffeic acid, danshensu, lithospermic acid, rosmarinic acid, salvianolic acid A, salvianolic acid B, salvianolic acid C, salvianolic acid D, and 3, 4-Dihydroxybenzaldehyde. In in vivo studies, the NS mice showed renal function and pathological impairment. Podocytes were damaged, with decreased levels of autophagy and apoptosis, accompanied by inhibition of the PI3K/AKT/mTOR signaling. DSI administration resulted in improved renal function and pathology in NS mice, with the activation of autophagy and PI3K/AKT/mTOR signaling in the kidneys. Additionally, podocytes were less damaged and intracellular autophagosomes were markedly increased. In vitro studies have shown that DSI activated MPC-5 autophagy and reduced apoptosis via the PI3K/AKT/mTOR pathway.

CONCLUSION

Collectively, this study demonstrated that DSI activated podocyte autophagy and reduced apoptosis via the PI3K/AKT/mTOR signaling, ultimately attenuating NS. Our study clarified the main components of DSI and elucidated its therapeutic effects and potential mechanisms for NS, providing new targets and agents for the clinical treatment of NS.

Estrogen deficiency aggravates fluoride-induced small intestinal mucosa damage and junctional complexes proteins expression disorder in rats

To investigate the effect of estrogen deficiency on the small intestinal mucosal barrier induced by fluoride (F), F exposure models of ovariectomy (OVX) rats (surgically removed ovaries) and non-OVX rats (normal condition) were established by adding sodium fluoride (NaF) (0, 25, 50, and 100 mg/L, calculated by F ion) in drinking water for 90 days. The intestinal mucosal histomorphology, mucosal barrier function, and protein expression levels of tight junctions (TJs), adhesion junctions (AJs), and desmosomes were evaluated in the duodenum, jejunum, and ileum. Hematoxylin-eosin (HE) staining and 5-Bromo-2-deoxyUridine (BrdU) measurement showed that excessive F-induced damage to intestinal epithelial cells and inhibited the proliferation of intestinal epithelial cells, eventually decreasing the number of goblet cells and decreasing glycoprotein secretion, as indicated by Alcian blue and periodic acid-Schiff (AB-PAS) and periodic acid-Schiff (PAS) staining. Further immunofluorescence analysis demonstrated that excessive F decreased the protein expression levels of occludin, zonula occludens-1 (ZO-1), E-cadherin, and desmoplakin (P < 0.05, P < 0.01) and enhanced the expression of claudin-2 (P < 0.01), suggesting that cell-to-cell junctions were disrupted. Collectively, F exposure impaired the small intestinal mucosal barrier by inducing damage to intestinal epithelial cells and inhibiting intestinal epithelial cell proliferation. Disorders in the junctional complex protein expression blocked the synergy between intercellular communication and aggravated mucosal injury. In particular, estrogen deficiency exacerbated F-induced enterotoxicity, which provides new explanations for the development and severity of intestinal disease in postmenopausal women with high-F areas.

Oxysophocarpine inhibits airway inflammation and mucus hypersecretion through JNK/AP-1 pathway in vivo and in vitro

Asthma is a high-incidence disease in the world. Oxysophocarpine (OSC), a quinolizidine alkaloid displays various pharmacological functions including anti-inflammation, neuroprotective, anti-virus and antioxidant. Here, we established mice and cell asthmatic model to explore the effects of OSC for asthma treatment. Mice were sensitized and challenged with ovalbumin (OVA) and treated with OSC before challenge. Enzyme-linked immuno sorbent assay (ELISA), hematoxylin and eosin (H&E), periodic acid-schiff (PAS), tolonium chloride staining and immunohistochemical assay were performed. OSC treatment inhibited inflammatory cell infiltration and mucus secretion in the airway, reduced IgE level in mouse serum and decreased IL-4, IL-5 production in bronchoalveolar lavage fluid (BALF). OSC also reduced the spleen index to regulate immune function. Meanwhile, NCI-H292 cells were induced by lipopolysaccharide (LPS) to simulate airway epithelial injury. OSC pretreatment decreased the IL-6 and IL-8 cytokine levels, mucin 5 AC expression, and mucin 5 AC mRNA level in the cell model. Further, OSC suppressed the phosphorylation of c-Jun N-terminal kinase (JNK), and activator protein 1 (AP-1, Fos and Jun). These findings revealed that OSC alleviated bronchial asthma associated with JNK/AP-1 signaling pathway.

Structural characterization and evaluation the elicitors activity of polysaccharides from Chrysanthemum indicum

This research evaluates the elicitors activity and structure characterization of four Chrysanthemum indicum polysaccharides (CIPs) which were isolated from C. indicum, obtained CIP1, CIP2, CIP3, CIP4. Results demonstrated that there was a distinct difference in inducibility and CIP3 was significantly stronger than other CIPs through bioactivity-tests. Taking CIP3 with total carbohydrate content 91.93 % as a representative, its structure was elucidated as a relative molecular weight of 8. 741 × 10³ g/mol and mainly composed of xylose, galacturonic acid, galactose and glucuronic acid. Through GC, IR and NMR, CIP3 was determined to possess a backbone comprised of T-α-d-GalpA, 1,4-α-d-GlcpA, 1,2-α-d-Xylp, 1,3-α-l-Rhap, 1,2,4-α-l-Rhap and sidechains comprised of 1,3-β-d-Galp, 1,6-α-d-Galp, T-α-Glcp, 1,3-β-d-Glcp, 1,4-α-d-Glcp, 1,3,4-α-d-Manp, T-α-l-Fucp. Further results indicated that CIP3 with active sidechains could significantly increase the expression of defense genes in Atractylodes macrocephala Koidz (AM). It is believed that the sidechains of CIP3 were necessary to its elicitor activity via bioactivity tests.

A major locus involved in the formation of the radial oxygen loss barrier in adventitious roots of teosinte Zea nicaraguensis is located on the short-arm of chromosome 3

A radial oxygen loss (ROL) barrier in roots of waterlogging-tolerant plants promotes oxygen movement via aerenchyma to the root tip, and impedes soil phytotoxin entry. The molecular mechanism and genetic regulation of ROL barrier formation are largely unknown. Zea nicaraguensis, a waterlogging-tolerant wild relative of maize (Zea mays ssp. mays), forms a tight ROL barrier in its roots when waterlogged. We used Z. nicaraguensis chromosome segment introgression lines (ILs) in maize (inbred line Mi29) to elucidate the chromosomal region involved in regulating root ROL barrier formation. A segment of the short-arm of chromosome 3 of Z. nicaraguensis conferred ROL barrier formation in the genetic background of maize. This chromosome segment also decreased apoplastic solute permeability across the hypodermis/exodermis. However, the IL and maize were similar for suberin staining in the hypodermis/exodermis at 40 mm and further behind the root tip. Z. nicaraguensis contained suberin in the hypodermis/exodermis at 20 mm and lignin at the epidermis. The IL with ROL barrier, however, did not contain lignin in the epidermis. Discovery of the Z. nicaraguensis chromosomal region responsible for root ROL barrier formation has improved knowledge of this trait and is an important step towards improvement of waterlogging tolerance in maize.

A major locus involved in the formation of the radial oxygen loss barrier in adventitious roots of teosinte Zea nicaraguensis is located on the short-arm of chromosome 3

A radial oxygen loss (ROL) barrier in roots of waterlogging-tolerant plants promotes oxygen movement via aerenchyma to the root tip, and impedes soil phytotoxin entry. The molecular mechanism and genetic regulation of ROL barrier formation are largely unknown. Zea nicaraguensis, a waterlogging-tolerant wild relative of maize (Zea mays ssp. mays), forms a tight ROL barrier in its roots when waterlogged. We used Z. nicaraguensis chromosome segment introgression lines (ILs) in maize (inbred line Mi29) to elucidate the chromosomal region involved in regulating root ROL barrier formation. A segment of the short-arm of chromosome 3 of Z. nicaraguensis conferred ROL barrier formation in the genetic background of maize. This chromosome segment also decreased apoplastic solute permeability across the hypodermis/exodermis. However, the IL and maize were similar for suberin staining in the hypodermis/exodermis at 40 mm and further behind the root tip. Z. nicaraguensis contained suberin in the hypodermis/exodermis at 20 mm and lignin at the epidermis. The IL with ROL barrier, however, did not contain lignin in the epidermis. Discovery of the Z. nicaraguensis chromosomal region responsible for root ROL barrier formation has improved knowledge of this trait and is an important step towards improvement of waterlogging tolerance in maize.

Periodic Acid-Schiff Staining with Diastase

Periodic Acid-Schiff (PAS) with diastase (PAS-D) refers to the use of the PAS stain in combination with diastase, which is an enzyme that digests the glycogen. The purpose of using the PAS-D procedure is to differentiate glycogen from other PAS-positive elements in tissue samples. The PAS-D method is also used for periportal liver staining of AAT polymer inclusions that are seen in alpha-1 antitrypsin deficiency disease. Here, we describe the procedure of PAS-D staining in formalin-fixed, paraffin-embedded human liver tissues.

Characterization of the N-glycans of female Angiostrongylus cantonensis worms

Glycoconjugates play a crucial role in the host-parasite relationships of helminthic infections, including angiostrongyliasis. It has previously been shown that the antigenicity of proteins from female Angiostrongylus cantonensis worms may depend on their associated glycan moieties. Here, an N-glycan profile of A. cantonensis is reported. A total soluble extract (TE) was prepared from female A. cantonensis worms and was tested by western blot before and after glycan oxidation or N- and O-glycosidase treatment. The importance of N-glycans for the immunogenicity of A. cantonensis was demonstrated when deglycosylation of the TE with PNGase F completely abrogated IgG recognition. The TE was also fractionated using various lectin columns [Ulex europaeus (UEA), concanavalin A (Con A), Arachis hypogaea (PNA), Triticum vulgaris (WGA) and Lycopersicon esculentum (LEA)], and then each fraction was digested with PNGase F. Released N-glycans were analyzed with matrix-assisted laser desorption ionization (MALDI)-time-of-flight (TOF)-mass spectrometry (MS) and MALDI-TOF/TOF-MS/MS. Complex-type, high mannose, and truncated glycan structures were identified in all five fractions. Sequential MALDI-TOF-TOF analysis of the major MS peaks identified complex-type structures, with a α1-6 fucosylated core and truncated antennas. Glycoproteins in the TE were labeled with BodipyAF558-SE dye for a lectin microarray analysis. Fluorescent images were analyzed with ProScanArray imaging software followed by statistical analysis. A total of 29 lectins showed positive binding to the TE. Of these, Bandeiraea simplicifolia (BS-I), PNA, and Wisteria floribunda (WFA), which recognize galactose (Gal) and N-acetylgalactosamine (GalNAc), exhibited high affinity binding. Taken together, our findings demonstrate that female A. cantonensis worms have characteristic helminth N-glycans.

Equine influenza serological methods

Serologic tests for equine influenza virus (EIV) antibodies are used for many purposes, including retrospective diagnosis, subtyping of virus isolates, antigenic comparison of different virus strains, and measurement of immune responses to EIV vaccines. The hemagglutination-inhibition (HI), single radial hemolysis (SRH), and serum micro-neutralization tests are the most widely used for these purposes and are described here. The presence of inhibitors of hemagglutination in equine serum complicates interpretation of HI assay results, and there are alternative protocols (receptor-destroying enzyme, periodate, trypsin-periodate) for their removal. With the EIV H3N8 strains in particular, equine antibody titers may be magnified by pretreating the HI test antigen with Tween-80 and ether. The SRH assay offers stronger correlations between serum antibody titers and protection from disease. Other tests are sometimes used for specialized purposes such as the neuraminidase-inhibition assay for subtyping, or ELISA for measuring different specific antibody isotypes, and are not described here.

The glycosylation pattern of common allergens: the recognition and uptake of Der p 1 by epithelial and dendritic cells is carbohydrate dependent

Allergens are initiators of both innate and adaptive immune responses. They are recognised at the site of entry by epithelial and dendritic cells (DCs), both of which activate innate inflammatory circuits that can collectively induce Th2 immune responses. In an attempt to have a better understanding of the role of carbohydrates in the recognition and uptake of allergens by the innate immune system, we defined common glycosylation patterns in major allergens. This was done using labelled lectins and showed that allergens like Der p 1 (Dermatophagoides pteronyssinus group 1), Fel d 1 (Felis domisticus), Ara h 1 (Arachis hypogaea), Der p 2 (Dermatophagoides pteronyssinus group 2), Bla g 2 (Blattella germanica) and Can f 1 (Canis familiaris) are glycosylated and that the main dominant sugars on these allergens are 1-2, 1-3 and 1-6 mannose. These observations are in line with recent reports implicating the mannose receptor (MR) in allergen recognition and uptake by DCs and suggesting a major link between glycosylation and allergen recognition. We then looked at TSLP (Thymic Stromal Lymphopoietin) cytokine secretion by lung epithelia upon encountering natural Der p 1 allergen. TSLP is suggested to drive DC maturation in support of allergic hypersensitivity reactions. Our data showed an increase in TSLP secretion by lung epithelia upon stimulation with natural Der p 1 which was carbohydrate dependent. The deglycosylated preparation of Der p 1 exhibited minimal uptake by DCs compared to the natural and hyperglycosylated recombinant counterparts, with the latter being taken up more readily than the other preparations. Collectively, our data indicate that carbohydrate moieties on allergens play a vital role in their recognition by innate immune cells, implicating them in downstream deleterious Th2 cell activation and IgE production.

Assay of deoxyhypusine hydroxylase activity

The eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains an unusual amino acid, hypusine [N (ε)-(4-amino-2-hydroxybutyl)-lysine]. eIF5A and its hypusine/deoxyhypusine modification are vital for eukaryotic cell proliferation. Hypusine is formed posttranslationally by two enzymatic steps catalyzed by deoxyhypusine synthase and deoxyhypusine hydroxylase. Deoxyhypusine hydroxylase catalyzes a stereo-specific hydroxylation of the deoxyhypusine residue in the eIF5A intermediate protein, eIF5A(Dhp). The enzyme is totally specific for this protein and does not act on short peptides (<50 amino acids). The assay measures the conversion of the radiolabeled deoxyhypusine residue to a hypusine residue in eIF5A. Optimum conditions for the reaction and two detection methods for the product, hypusine-containing eIF5A, are described in this chapter. The first, and most reliable, method is the measurement of the amount of [(3)H]hypusine in the protein hydrolysate after its separation from [(3)H]deoxyhypusine, by ion exchange chromatography. This method does require specialized equipment. The second method is based on counting the total TCA soluble radioactivity after sodium periodate oxidation of the reaction mixture, since the radiolabeled 4-amino-2-hydroxy butyl moiety of the hypusine residue is cleaved and is released from protein as radiolabeled β-propionaldehyde and formaldehyde by periodate oxidation.

Antibody isotype analysis of malaria-nematode co-infection: problems and solutions associated with cross-reactivity

BACKGROUND

Antibody isotype responses can be useful as indicators of immune bias during infection. In studies of parasite co-infection however, interpretation of immune bias is complicated by the occurrence of cross-reactive antibodies. To confidently attribute shifts in immune bias to the presence of a co-infecting parasite, we suggest practical approaches to account for antibody cross-reactivity. The potential for cross-reactive antibodies to influence disease outcome is also discussed.

RESULTS

Utilising two murine models of malaria-helminth co-infection we analysed antibody responses of mice singly- or co-infected with Plasmodium chabaudi chabaudi and Nippostrongylus brasiliensis or Litomosoides sigmodontis. We observed cross-reactive antibody responses that recognised antigens from both pathogens irrespective of whether crude parasite antigen preparations or purified recombinant proteins were used in ELISA. These responses were not apparent in control mice. The relative strength of cross-reactive versus antigen-specific responses was determined by calculating antibody titre. In addition, we analysed antibody binding to periodate-treated antigens, to distinguish responses targeted to protein versus carbohydrate moieties. Periodate treatment affected both antigen-specific and cross-reactive responses. For example, malaria-induced cross-reactive IgG1 responses were found to target the carbohydrate component of the helminth antigen, as they were not detected following periodate treatment. Interestingly, periodate treatment of recombinant malaria antigen Merozoite Surface Protein-119 (MSP-119) resulted in increased detection of antigen-specific IgG2a responses in malaria-infected mice. This suggests that glycosylation may have been masking protein epitopes and that periodate-treated MSP-119 may more closely reflect the natural non-glycosylated antigen seen during infection.

CONCLUSIONS

In order to utilize antibody isotypes as a measure of immune bias during co-infection studies, it is important to dissect antigen-specific from cross-reactive antibody responses. Calculating antibody titre, rather than using a single dilution of serum, as a measure of the relative strength of the response, largely accomplished this. Elimination of the carbohydrate moiety of an antigen that can often be the target of cross-reactive antibodies also proved useful.

Allergen-induced asthma in C57Bl/6 mice: hyper-responsiveness, inflammation and remodelling

The relationship among airway responsiveness, inflammation and remodelling in asthma is incompletely understood. To investigate potential mechanistic associations, allergen-induced asthma was studied in C57Bl/6 mice. Mice were sensitized and challenged with ovalbumin (OVA) using sub-acute (SA) or chronic (C) protocols. Responsiveness was assessed by measuring respiratory impedence which was partitioned into airway resistance (Raw) and distal lung components (Gti, Hti) during methacholine-induced constriction. Inflammation, airway mucus, airway smooth muscle, collagen, biglycan and decorin were quantified. The airways were sub-divided into central or peripheral. In SA and C OVA, Raw, Gti and Hti responsiveness were significantly increased; the peripheral response was significantly greater in SA vs C OVA. Airway inflammation and mucus were increased in both groups, but more significantly in peripheral airways in SA OVA. In the SA OVA model, inflammation and mucus appear to drive the mechanical response, especially in the lung periphery; airway remodelling seems to contribute to hyper-responsiveness to an equivalent degree, after both challenge protocols.

Susceptibility of staphylococcal biofilms to enzymatic treatments depends on their chemical composition

Bacterial infections are serious complications after orthopaedic implant surgery. Staphylococci, with Staphylococcus epidermidis as a leading species, are the prevalent and most important species involved in orthopaedic implant-related infections. The biofilm mode of growth of these bacteria on an implant surface protects the organisms from the host's immune system and from antibiotic therapy. Therapeutic agents that disintegrate the biofilm matrix would release planktonic cells into the environment and therefore allow antibiotics to eliminate the bacteria. An addition of a biofilm-degrading agent to a solution used for washing-draining procedures of infected orthopaedic implants would greatly improve the efficiency of the procedure and thus help to avoid the removal of the implant. We have previously shown that the extracellular staphylococcal matrix consists of a poly-N-acetylglucosamine (PNAG), extracellular teichoic acids (TAs) and protein components. In this study, we accessed the sensitivity of pre-formed biofilms of five clinical staphylococcal strains associated with orthopaedic prosthesis infections and with known compositions of the biofilm matrix to periodate, Pectinex Ultra SP, proteinase K, trypsin, pancreatin and dispersin B, an enzyme with a PNAG-hydrolysing activity. We also tested the effect of these agents on the purified carbohydrate components of staphylococcal biofilms, PNAG and TA. We found that the enzymatic detachment of staphylococcal biofilms depends on the nature of their constituents and varies between the clinical isolates. We suggest that a treatment with dispersin B followed by a protease (proteinase K or trypsin) could be capable to eradicate biofilms of a variety of staphylococcal strains on inert surfaces.

A simple and high sensitive spectrophotometric method for ultra trace determination of ruthenium with its catalytic effect on the oxidation of pyronin B by periodate

A new simple, selective, high sensitive and rapid method has been developed for spectrophotometric determination of ultra trace amounts of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate at lambdamax=555 nm. The described method is able to quantify ruthenium in the range of 0.1-100 ng ml-1 (r=0.9973), with a detection limit (S/N=3) of 0.036 ng ml-1. Under optimum conditions, this procedure has been successfully applied to determine the trace levels of ruthenium in the environmental and biological samples. The precision, expressed as relative standard deviation of three measurements, is better than 2.44%.

Kinetic characterization of the oxidation of esculetin by polyphenol oxidase and peroxidase

Esculetin has been described as an inhibitor of tyrosinase and polyphenol oxidase and, therefore, of melanogenesis. In this work, we demonstrate that esculetin is not an inhibitor but a substrate of mushroom polyphenol oxidase (PPO) and horseradish peroxidase (POD), enzymes which oxidize esculetin, generating its o-quinone. Since o-quinones are very unstable, the usual way of determining the enzymatic activity (slope of recordings) is difficult. For this reason, we developed a chronometric method to characterize the kinetics of this substrate, based on measurements of the lag period in the presence of micromolar concentrations of ascorbic acid. The catalytic constant determined was of the same order for both enzymes. However, polyphenol oxidase showed greater affinity (a lower Michaelis constant) than peroxidase for esculetin. The affinity of PPO and POD towards oxygen and hydrogen peroxide was very high, suggesting the possible catalysis of both enzymes in the presence of low physiological concentrations of these oxidizing substrates. Taking into consideration optimum pHs of 4.5 and 7 for POD and PPO respectively, and the acidic pHs of melanosomes, the studies were carried out at pH 4.5 and 7. The in vivo pH might be responsible for the stronger effect of these enzymes on L-tyrosine and L-3,4-dihydroxyphenylanaline (L-DOPA) (towards melanogenesis) and on cumarins such as esculetin towards an alternative oxidative pathway.

Kinetic characterization of the oxidation of chlorogenic acid by polyphenol oxidase and peroxidase. Characteristics of the o-quinone

Chlorogenic acid is the major diphenol of many fruits, where it is oxidized enzymatically by polyphenol oxidase (PPO) or peroxidase (POD) to its o-quinone. In spectrophotometric studies of chlorogenic acid oxidation with a periodate ratio of [CGA]0/[IO4-]0 < 1 and [CGA]0/[IO4-]0 > 1, the o-quinone was characterized as follows: lambda(max) at 400 nm and epsilon = 2000 and 2200 M-1 cm-1 at pH 4.5 and 7.0, respectively. In studies of o-quinone generated by the oxidation of chlorogenic acid using a periodate at ratio of [CGA]0/[IO4-]0 > 1, a reaction with the remaining substrate was detected, showing rate constants of k = 2.73 +/- 0.17 M-1 s-1 and k' = 0.05 +/- 0.01 M-1 s-1 at the above pH values. A chronometric spectrophotometric method is proposed to kinetically characterize the action of the PPO or POD on the basis of measuring the time it takes for a given amount of ascorbic acid to be consumed in the reaction with the o-quinone. The kinetic constants of mushroom PPO and horseradish POD are determined.

Extracellular ATP has stimulatory effects on the expression and release of IL-6 via purinergic receptors in normal human epidermal keratinocytes

Extracellular ATP regulates proliferation and differentiation, functioning as an important messenger via purinergic (P2) receptors in keratinocytes. In this study, we investigated the effects of ATP on cytokine production in cultured normal human epidermal keratinocytes (NHEKs). Adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), adenosine 5'-O-2-(thio)diphosphate (ADPbetaS), ADP, ATP, and 2', 3'-O-(4-benzoyl-benzoyl) ATP (BzATP) significantly increased the release of IL-6. The P2 antagonists, suramin-, reactive blue 2-, and periodate-oxidized ATP, inhibited ATP-induced IL-6 release, whereas pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid, adenosine 3'-phosphate 5'-phosphate, 1-[N,O-bis(1,5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine, and pertussis toxin did not. SQ22563, an adenylate cyclase inhibitor, inhibited ATP-induced IL-6 release. ATPgammaS, ADPbetaS, ATP, and BzATP significantly increased the intracellular cAMP content. Reverse transcription-PCR showed expression of P2Y1, P2Y2, P2Y4, P2Y11, P2Y12, P2Y13, P2X1, P2X4, P2X5, P2X6, and P2X7 receptor subtypes. Additionally, UVB radiation evoked the release of ATP from NHEKs. The release of IL-6 and the expression of IL-6 mRNA were increased after UVB radiation, and these increases were also inhibited by P2 receptor antagonists. These results suggest that cAMP-generating P2Y receptors are likely functional in ATP-induced IL-6 production in NHEKs. Furthermore, in UVB-radiated cells, we note the possibility that P2 receptor antagonists may reduce skin inflammation.

Isolation, purification and structural investigation of a water-soluble polysaccharide from Solanum lyratum Thunb

Polysaccharides, extracted from the herbs of Chinese natural Solanum lyratum Thunb (SLT), which is a traditional Chinese medicine with hot water and 0.04 M sodium hydroxide successively, were fractionated and purified by ion-exchange and gel-filtration chromatography. According to methylation, periodate oxidation, NMR spectroscopy, partial and graded acid and enzymic hydrolysis analysis, the results indicated the D-glucan to be linear and to contain both (1-->3)- and (1-->4)-linkages. The anomeric NMR and IR spectra measurements confirmed that the sugar residues were beta-glycosidically linked.

Use of monoclonal antibodies to quantify the dynamics of alpha-galactosidase and endo-1,4-beta-glucanase production by Trichoderma hamatum during saprotrophic growth and sporulation in peat

Trichoderma species are ubiquitous soil and peat-borne saprotrophs that have received enormous scientific interest as biocontrol agents of plant diseases caused by destructive root pathogens. Mechanisms of biocontrol such as antibiosis and hyperparasitism are well documented and the biochemistry and molecular genetics of these processes defined. An aspect of biocontrol that has received little attention is the ability of Trichoderma species to compete for nutrients in their natural environments. Trichoderma species are efficient producers of polysaccharide-degrading enzymes that enable them to colonize organic matter thereby preventing the saprotrophic spread of plant pathogens. This study details the use of monoclonal antibodies (mAbs) to quantify the production of two enzymes implicated in the saprotrophic growth of Trichoderma species in peat. Using mAbs specific to the hemicellulase enzyme alpha-galactosidase (AGL) and the cellulase enzyme endo-1,4-beta-glucanase (EG), the relationship between the saprotrophic growth dynamics of a biocontrol strain of Trichoderma hamatum and the concomitant production of these enzymes in peat-based microcosms was studied. Enzyme activity assays and enzyme protein concentrations derived by enzyme-linked immunosorbent assay (ELISA) established the precision and sensitivity of mAb-based assays in quantifying enzyme production during active growth of the fungus. Trends in enzyme activities and protein concentrations were similar for both enzymes, during a 21-day sampling period in which active growth and sporulation of the fungus in peat was quantified using an independent mAb-based assay. There was a sharp increase in active biomass of T. hamatum 3 days after inoculation of microcosms with phialoconidia. After 3 days there was a rapid decline in active biomass which coincided with sporulation of the fungus. A similar trend was witnessed with EG activities and concentrations. This showed that EG production related directly to active growth of the fungus. The trend was not found, however, with AGL. There was a rapid increase in enzyme activities and protein concentrations on day 3, after which they remained static. The reason for the maintenance of elevated AGL probably resulted from secretion of the enzyme from conidia and chlamydospores. ELISA, immunofluoresence and immunogold electron microscopy studies of these cells showed that the enzyme is localized within the cytoplasm and is secreted extracellularly into the surrounding environment. It is postulated that release of oligosaccharides from polymeric hemicellulose by the constitutive spore-bound enzyme leads to AGL induction and could act as an environmental cue for spore germination.

Vitamin C degradation in plant cells via enzymatic hydrolysis of 4-O-oxalyl-l-threonate

Increasing the L-ascorbate (vitamin C) content of crops could in principle involve promoting its biosynthesis or inhibiting its degradation. Recent progress has revealed biosynthetic pathways for ascorbate, but the degradative pathways remain unclear. The elucidation of such pathways could promote an understanding of the roles of ascorbate in plants, and especially of the intriguing positive correlation between growth rate and ascorbate oxidase (or its products). In some plants (Vitaceae), ascorbate is degraded via L-idonate to L-threarate (L-tartrate), with the latter arising from carbons 1-4 of ascorbate. In most plants, however (including Vitaceae), ascorbate degradation can occur via dehydroascorbate, yielding oxalate plus L-threonate, with the latter from carbons 3-6 of ascorbate. The metabolic steps between ascorbate and oxalate/L-threonate, and their subcellular location, were unknown. Here we show that this pathway operates extracellularly in cultured Rosa cells, proceeds via several novel intermediates including 4-O-oxalyl-L-threonate, and involves at least one new enzyme activity. The pathway can also operate non-enzymatically, potentially accounting for vitamin losses during cooking. Several steps in the pathway may generate peroxide; this may contribute to the role of ascorbate as a pro-oxidant that is potentially capable of loosening the plant cell wall and/or triggering an oxidative burst.

Adherence of Brucella to human epithelial cells and macrophages is mediated by sialic acid residues

The basis for the interaction of Brucella species with the surface of epithelial cells before migration in the host within polymorphonuclear leucocytes is largely unknown. Here, we studied the ability of Brucella abortus and Brucella melitensis to adhere to cultured epithelial (HeLa and HEp-2) cells and THP-1-derived macrophages, and to bind extracellular matrix proteins (ECM). The brucellae adhered to epithelial cells forming localized bacterial microcolonies on the cell surface, and this process was inhibited significantly by pretreatment of epithelial cells with neuraminidase and sodium periodate and by preincubation of the bacteria with heparan sulphate and N-acetylneuraminic acid. Trypsinization of epithelial cells yielded increased adherence, suggesting unmasking of target sites on host cells. Notably, the brucellae also adhered to cultured THP-1 cells, and this event was greatly reduced upon removal of sialic acid residues from these cells with neuraminidase. B. abortus bound in a dose-dependent manner to immobilized fibronectin and vitronectin and, to a lesser extent, to chondroitin sulphate, collagen and laminin. In sum, our data strongly suggest that the adherence mechanism of brucellae to epithelial cells and macrophages is mediated by cellular receptors containing sialic acid and sulphated residues. The recognition of ECM (fibronectin and vitronectin) by the brucellae may represent a mechanism for spread within the host tissues. These are novel findings that offer new insights into understanding the interplay between Brucella and host cells.

Quick two-step RNA ligation employing periodate oxidation

The introduction of modified or labeled nucleotides into RNA is a powerful RNA engineering tool as it enables us to investigate how native RNA modifications affect RNA function and structure. It also helps in the structural analysis of RNA. A modified nucleotide can be introduced into a specific position of RNA by the method of two-step enzymatic ligation of RNA fragments. However, this method requires a complicated purification step between the two ligation steps that results in low yields of the ligation product. Here we have developed a new ligation technique employing periodate oxide that eliminates this purification step. This increases the total yield of the ligation product and makes it a faster procedure.

The influence of surface carbohydrates during in vitro infection of mammalian cells by the dermatophyte Trichophyton rubrum

In order to better understand the role played by surface glycoconjugates during host cell adhesion and endocytosis of Trichophyton rubrum, we looked for the presence of carbohydrate-binding adhesins on the microconidia surface and their role on cellular interaction with epithelial and macrophages cells. The interaction of T. rubrum with chinese hamster ovary epithelial cells and their glycosylation-deficient mutants demonstrated a higher adhesion index in Lec1 and Lec2 mutants, that express mannose and galactose, respectively. Endocytosed fungi were shown preferentially in Lec2 cells. Addition of the carbohydrates to the interaction medium, pretreatment with lectins and with sodium periodate decreased the adhesion and endocytic index for all mutants. The ability of the fungus to penetrate into mammalian cells was confirmed in experiments using macrophages treated with cytochalasin D. Flow cytometric analysis showed that this fungus recognizes mannose and galactose. The binding was inhibited by the addition of methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside, and showed higher fluorescence intensity at 37 than at 28 degrees C. Trypsin treatment and heating of the cells reduced the binding, suggesting a (glyco) protein nature for the microconidia adhesins. The presence of lectin-like molecules in fungus cell could be observed by scanning electron microscopy of the fungus incubated with colloidal-gold labeled neoglycoproteins. Our results suggest that T. rubrum has the ability to invade mammalian cells and expresses carbohydrate-specific adhesins on microconidia surface that recognize mannose and galactose. These adhesins may play an important role on the adhesion and invasion of the fungus during the infectious process of dermatophytosis.

Echinococcus granulosus coproantigens: chromatographic fractionation and characterization

Dogs infected with adult tapeworms of Echinococcus granulosus release antigens (coproantigens) in faeces which can be detected by a capture ELISA. Supernatants prepared from E. granulosus-infected dog faecal samples were fractionated by size-exclusion fast protein liquid chromatography (FPLC) on a Superose-6 column. Coproantigen ELISA and Western blotting were used to demonstrate the immunoreactivity of eluted fractions. Two main FPLC peaks of antigenic activity were detected and designated as fraction F1 and fraction F2 with approximate relative molecular weights > 670 kDa, and in the range of 146 to 440 kDa respectively. These two antigenic fractions (F1 and F2) fractionated from infected dog faeces were heat stable and largely protease-insensitive, but were highly sensitive to sodium periodate treatment, which strongly suggested the involvement of carbohydrates. Capture IgG antibodies against E. granulosus proglottis somatic extracts, detected a molecule with an approximate molecular weight of 155 kDa in fraction F2 after immunoblotting. The 155 kDa antigen could be completely ablated by sodium periodate treatment, but not after protease or lipase treatment. A surface tegument preparation of adult E. granulosus tapeworms contained large amounts of antigen that corresponded in size range and antigenicity to that observed in the FPLC fraction F2. There was also a peak of antigenic activity at > 670 kDa corresponding to fraction F1 from a culture derived excretory-secretory (E-S) adult tapeworm preparation. The involvement of carbohydrate moieties in coproantigen activity present in the FPLC fractions F1 and F2 from faecal supernatants of E. granulosus-infected dogs was confirmed by lectin-binding assays and exoglycosidase treatment, which showed that alpha-D-mannose and/or alpha-D-glucose, beta-galactose and N-acetyl-beta-glucosamine residues were the most important carbohydrate components in putative coproantigens present in both fractions. N-acetyl-beta-glucosamine and sialic acid residues were also contained in coproantigen molecules present in fraction F2. These results suggested that coproantigens detected in faeces of E. granulosus-infected dogs are large molecular weight molecules that may be derived from the carbohydrate-rich surface glycocalyx of adult worms, and are shed, released or secreted during the life-span of the tapeworm.

A New Glycoprotein Allergen/Antigen with the Protease Activity from Aspergillus fumigatus

BACKGROUND

Aspergillus fumigatus is an opportunistic fungus causing allergic and invasive aspergillosis in humans and animals. It secretes an array of complex biologically active glycoprotein antigens and allergens. It is important to identify and characterize probable potential virulent factors playing a major role in the pathogenesis of aspergillosis.

METHODS

Using protein purification techniques (lectin affinity chromatography, gel filtration, electroelution and high-pressure liquid chromatography), a major antigen/allergen with a molecular weight of 56 kD (gp56) from A. fumigatus was purified to homogeneity. The protein was characterized by immunoblot, ELISA and protease assays. The N-terminal amino acid sequencing was performed.

RESULTS

The gp56 protein showed a single band on silver staining and isoelectric focussing. The protein to carbohydrate ratio was 1.5:1 and gp56 gave a protein band at a molecular weight of 34 kD on enzymatic deglycosylation. It also exhibited IgG and IgE immunobinding with antibodies present in sera of allergic bronchopulmonary aspergillosis patients. The gp56 exhibited protease activity and N-terminal seven-amino acid sequence showed homology with fungal serine proteases.

CONCLUSIONS

The gp56 protein by virtue of its proteolytic activity could be one of the virulent factors of A. fumigatus involved in establishing infection in the host along with other factors.

Association of Flavobacterium psychrophilum with rainbow trout (Oncorhynchus mykiss) kidney phagocytes in vitro

The capacity of virulent and non-virulent strains of Flavobacterium psychrophilum of different serotypes to associate with isolated rainbow trout (Oncorhynchus mykiss, 300-500 g) kidney phagocytes was evaluated in vitro. The results showed that F. psychrophilum was associated with the phagocytes but large differences in association were observed between the different bacterial strains examined. These differences in association with the phagocytes was not clearly related to the serotype or virulence of the bacteria, although all strains tested of the non-virulent serotype FpT showed strong association with the isolated phagocytes. A competitive association assay with treatment of the phagocytes with seven different carbohydrates, suggested a role for N-acetylneuraminic acid (sialic acid) in the binding of F. psychrophilum to phagocytes. A significant dose dependent inhibition of the association was observed with sialic acid. Treatment of F. psychrophilum with sodium-metaperiodate showed that carbohydrate components play a role in the adhesion of the bacteria to the phagocytes. The results indicate that the binding of F. psychrophilum to rainbow trout kidney phagocytes can be mediated by opsonin independent cell-receptor adhesion. All tested strains seemed to be non-cytotoxic for rainbow trout kidney phagocytes in vitro suggesting that a phagocyte toxin is not necessary for the virulence of F. psychrophilum

The kinetics of periodate oxidation of carbohydrates 2. Polymeric substrates

A study of the kinetics of periodate oxidation on a series of dextran oligomers and polymers is carried out by isothermal microcalorimetry. In addition to these substrates, some dimeric carbohydrates and hyaluronan were studied. Rate constants were calculated from the calorimetric decay curves, which, properly corrected for calorimetric response, are proportional to the rate of periodate conversion. The dependence of the kinetic rates on the molecular weight of dextran samples and on the substrate concentration, is described in terms of the much higher rates of terminal reducing units. The presence of two sites with comparable reaction rates makes the analysis of the calorimetric curves difficult, even in the simple overall pseudo-first-order condition. The suitability of a phenomenological treatment of kinetic data is explored.

Syndecan-1/CD138 expression in normal myeloid, acute lymphoblastic and myeloblastic leukemia cells

Stabilization of cell surface antigens and preservation of ultrastructural integrity are important aspects of immunoelectron microscopical studies. In the present study, 4 anti-syndecan-1/CD138 (B-B2, B-B4, MI15, 1D4) monoclonal antibodies (mAbs) were applied in combination with periodatelysine-paraformaldehyde (PLP) fixation and indirect pre-embedding peroxidase electron microscopical immunocytochemistry to analyse the localization and function of these molecules in normal myeloid cells, acute lymphoblastic leukemia (ALL) cells and acute myeloblastic leukemia (AML) cells. One case of normal human bone marrow, 3 cases of untreated AML and 2 cases of untreated ALL were studied. Samples were immediately fixed for 4 h in freshly-prepared PLP fixative in 0.037 mol/L phosphate buffer, pH 7.4, containing 10 mmol/L sodium metaperiodate, 75 mmol/L lysine, and 2% paraformaldehyde. Expression of syndecan-1 was found at the plasma membrane of all cell types. Staining intensity at the membrane of AML cells was stronger than that on the membrane of normal myeloid and ALL cells. We conclude that anti-syndecan-1/CD138 mAbs in combination with the method described here are a suitable tool for detection of cell surface syndecan molecules in cells originating from progenitor cells that can differentiate in both myeloid and lymphoid cells.

Immunohistochemical artifact for nitrotyrosine in eosinophils or eosinophil containing tissue

Immunohistochemical artifacts for nitrotyrosine were investigated in eosinophils with regard to fixatives. Immunoreactivity for nitrotyrosine was revealed in separated eosinophils and in gastric mucosa fixed with periodate, lysine-paraformaldehyde (PLP). The increase in immunoreactivity by PLP was due to periodate itself, a component of PLP. Nitrotyrosine formed by peroxidase using NO2- and H2O2 or by peroxynitrite was not completely inhibited by 100 mM dithionite but the immunoreactivity for nitrotyrosine antibodies by PLP was completely inhibited by 5.7 mM dithionite. Although untreated eosinophils or ovalbumin (OVA) did not show protein tyrosine nitration in a standard Western blot, the treatment of the blotted membrane with PLP increased the reactivities of proteins from eosinophils with anti-nitrotyrosine antibodies. The increase in immunoreactivity of OVA with anti-nitrotyrosine antibodies by PLP did not change with pre-treatment with dithionite but was abolished by treatment with dithionite after PLP fixation. In HPLC assays, periodate did not generate nitrotyrosine from L-tyrosine and aminotyrosine. These results suggest that the treatment of eosinophils or eosinophil-containing tissues with PLP fixative augments the immunoreactivity of nitrotyrosine antibodies with eosinophils due to the formation of epitopes similar to nitrotyrosine by an oxidation reaction of periodate, which evokes an artifact in nitrotyrosine immunohistochemistry.

Quality control of polyvalent pneumococcal polysaccharide-protein conjugate vaccine by nephelometry

A nephelometric method was used for quantitative analysis of individual polysaccharides (PSs) in a polyvalent pneumococcal conjugate vaccine using CRM(197) as carrier protein. Using this method, the individual types 4, 6B, 9V, 14, 18C, 19F and 23F PSs were found to range between 82.3 to 119% of the manufacturer's indicated values. During conjugation using reductive amination, pneumococcal PS was first oxidized to introduce aldehyde groups. Higher or lower levels of antigen-antibody reaction were observed in periodate activated and then reduced PS of some serotypes compared to non-treated PS. Use of oxidized and reduced PS may provide an early indication of change in conjugation process. Furthermore, since the final monovalent and polyvalent conjugate vaccines gradually change during the storage period, the nephelometry provides an useful analytical method for stability study of these vaccines.

Titrimetric micro-determination of therapeutically active phenothiazines using periodate

Two new simple, accurate and precise titrimetric micro-procedures are described for the analysis of phenothiazines in pure sample, tablets, injections and syrup using periodate as the oxidant. The first method is based on the oxidation of phenothiazines with periodate in acid medium and the iodate formed in the reaction is determined by reacting it with iodide and titrating the liberated iodine with thiosulfate after masking the excess of periodate with molybdate. In the second procedure, the unreacted (excess) periodate is determined iodometrically under basic conditions. The reaction conditions have been optimised and the stoichiometry of the reaction has been evaluated. A linear relationship exists between the amount of the drug and the titration end-point as shown by the values of correlation coefficient, r (0.9991-0.9999). The slope of the linear relationship has been calculated and found to be in the range, 0.1457-0.3120. The methods were applied to the analysis of dosage forms with results comparable to those given by the official methods. Both the methods are indirect visual titration methods, and are simpler than, and superior to, many existing methods for the assay of phenothiazines.

The structure of a polysaccharide from infectious strains of Burkholderia cepacia

The structure of an acidic exopolysaccharide (EPS) from eight strains of Burkholderia cepacia has been investigated by methylation and sugar analysis, periodate oxidation-Smith degradation, and partial acid-hydrolysis. An enzyme preparation obtained from the same organisms producing the EPS was also used to depolymerize the polysaccharide. Detailed NMR studies of the chemical and enzymatic degradation products showed that this EPS consists of a highly branched heptasaccharide-repeating unit with the following structure: [abstract: see text]. About three O-acetyl groups per repeating unit are present at undetermined positions.

Gravitational effects on mammalian cells

In this paper we present first the results of our most recent investigations on gravitational effects on the activation of human lymphocytes: by immunoenzymatic staining and by using concanavalin A (Con A) coated to red blood cells (RBC) we demonstrate that the increase of activation measured at 10xg is due to a simultaneous activation of T- and B-lymphocytes whereas at 1xg only T-cells are stimulated. Conversely, activation of T-cells by chemical modification of the membrane with sodium periodate is depressed at 10xg. Secondly, experiments performed in the centrifuge as well as in the clinostat with Friend, K-562, and hybridoma cells show that each cell line develops its own adaptation reaction to gravitational stress.

Seromucous cells in human sublingual glands: examination by immunocytochemistry of lysozyme

This study examined the occurrence and morphological features of serous-type cells in human sublingual gland, using immunocytochemistry for lysozyme. Lysozyme-positive cells usually formed demilunes and occasionally their own acini. They were also found among cells of an intercalated duct and in its immature acinus consisting of a small number of secretory cells. All these serous cells could be classified as seromucous cells because they simultaneously revealed reactivity for mucus, i.e., a periodic acid-Schiff (PAS) and a periodic acid-thiocarbohydrazide-silver proteinate (PA-TCHSP) reaction under the light- and electron-microscope, respectively. Immunogold labeling of lysozyme in the seromucous cells was distributed on variously sized secretory granules. These usually possessed a single electron-dense spherule in an electron-lucent matrix, while granules of a homogenous structure were also present. Lysozyme-positive cells filled with large, lucent secretory granules could hardly be morphologically distinguished from the lysozyme-negative mucous cells; they corresponded to "intermediate" cells designated under the light microscope. All "immature" secretory cells with only a few secretory granules were also lysozyme-positive seromucous cells. The present study demonstrated that the seromucous cells in the human sublingual glands conform closely with those in the human labial glands (MIYAZAKI et. al., 1998).

Synthesis and properties of oligonucleotides containing 5-formyl-2'-deoxycytidine: in vitro DNA polymerase reactions on DNA templates containing 5-formyl-2'-deoxycytidine

Oligodeoxynucleotides (ODNs) containing 5-formyl-2'-deoxycytidine (fC) were synthesized by the phosphoramidite method and subsequent oxidation with sodium periodate. The stabilities of duplexes containing A, G, C or T opposite fC were studied by thermal denaturation. It was found that fC:A, fC:C or fC:T base pairs significantly reduce the thermal stabilities of duplexes. Next, single nucleotide insertion reactions were performed using ODNs containing fC as templates and the Klenow fragment of Escherichia coli DNA polymerase I. It was found that: (i) insertion of dGMP opposite fC appears to be less efficient relative to insertion opposite 5-methyl-2'-deoxycytidine (mC); (ii) dAMP is misincorporated more frequently opposite fC than mC, although the frequency of misincorporation seems to be dependent on the sequence; (iii) TMP is misincorporated more frequently opposite fC than mC. These results suggest that fC may induce the transition mutation C.G-->T.A and the transversion mutation C.G-->A.T during DNA synthesis.

Binding patterns of 51 monoclonal antibodies to peptide and carbohydrate epitopes of the epithelial mucin (MUC1) on tissue sections of adenolymphomas of the parotid (Warthin's tumours): role of epitope masking by glycans

Warthin's tumours provide a unique opportunity to distinguish and compare monoclonal antibodies (mAbs) to the epithelial mucin, MUC1. In this study, we have applied the range of anti-MUC1 antibodies submitted to the ISOBM TD-4 Workshop for this purpose. mAbs and lectins against MUC1-associated carbohydrate epitopes were also included. Among 39 mAbs to peptide epitopes of MUC1, eight distinct types of staining patterns towards the two epithelial cell layers of Warthin's tumours could be observed. A majority of 27 mAbs reacted preferentially (17) or exclusively (10) with columnar cells, whereas 10 mAbs favoured basal cells (1 of them almost exclusively). The observed staining patterns revealed no correlation with the epitopes. However, after carbohydrate-specific periodate oxidation, 33 of the mAbs stained columnar and basal cells equally well, indicating that epitope masking by glycan side chains was in most cases responsible for the different staining patterns. The results demonstrate the profound impact of glycosylation on immunohistochemistry. Among carbohydrate epitopes, sialyl-TF, sialyl-Le(x), sialyl-dimeric Le(x) and Tn were expressed on both columnar and basal cells (the s-TF3 isomer on columnar cells only). The carcinoma-associated Thomsen-Friedenreich epitope was absent.

26-Hydroxylation of 1α,25-Dihydroxyvitamin D3 Does Not Occur under Physiological Conditions

The 26-hydroxylation of 1alpha,25-dihydroxyvitamin D3 in rats in vitro and in vivo was studied under physiological conditions. Incubation of 1alpha,25-dihydroxy-[26,27-3H]vitamin D3 with rat kidney or rat liver homogenate showed formation of a metabolite that was identified as 1alpha,25(S),26-trihydroxy-[26,27-3H]vitamin D3 by comigration on three different HPLC systems and a periodate cleavage reaction. This metabolite was not generated by hydroxylation of 1alpha,25-dihydroxy-[26,27-3H]vitamin D3 itself but by an enzymatic conversion of a precursor that was formed nonenzymatically in substantial amounts upon storage of 1alpha,25-dihydroxy-[26,27-3H]vitamin D3 in ethanol at -20 degrees C under argon for more than three weeks. An in vivo metabolism study in rats dosed with a physiological dose of 1alpha,25-dihydroxy-[26,27-3H]vitamin D3 confirmed the absence of 26-hydroxylation of the hormone. As expected at 6 h postinjection of purified 1alpha,25-dihydroxy-[26,27-3H]vitamin D3, 1alpha,24(R),25-trihydroxy-[26,27-3H]vitamin D3, as well as traces of (23S,25R)-1alpha,25-dihydroxy-[3H]vitamin D3-lactone were detected and identified on straight phase and reverse phase HPLC in serum, kidney, and liver.

Hypersulfated low molecular weight heparin with reduced affinity for antithrombin acts as an anticoagulant by inhibiting intrinsic tenase and prothrombinase

In buffer systems, heparin and low molecular weight heparin (LMWH) directly inhibit the intrinsic factor X-activating complex (intrinsic tenase) but have no effect on the prothrombin-activating complex (prothrombinase). Although chemical modification of LMWH, to lower its affinity for antithrombin (LA-LMWH) has no effect on its ability to inhibit intrinsic tenase, N-desulfation of LMWH reduces its activity 12-fold. To further explore the role of sulfation, hypersulfated LA-LMWH was synthesized (sLA-LMWH). sLA-LMWH is not only a 32-fold more potent inhibitor of intrinsic tenase than LA-LMWH; it also acquires prothrombinase inhibitory activity. A direct correlation between the extent of sulfation of LA-LMWH and its inhibitory activity against intrinsic tenase and prothrombinase is observed. In plasma-based assays of tenase and prothrombinase, sLA-LMWH produces similar prolongation of clotting times in plasma depleted of antithrombin and/or heparin cofactor II as it does in control plasma. In contrast, heparin has no effect in antithrombin-depleted plasma. When the effect of sLA-LMWH on various components of tenase and prothrombinase was examined, its inhibitory activity was found to be cofactor-dependent (factors Va and VIIIa) and phospholipid-independent. These studies reveal that sLA-LMWH acts as a potent antithrombin-independent inhibitor of coagulation by attenuating intrinsic tenase and prothrombinase.

Glycoinositolphosphosphingolipids (basidiolipids) of higher mushrooms

The basidiolipids of six mushroom species, i.e. the basidiomycetes Amanita virosa (engl., death cup), Calvatia exipuliformis (engl., puffball), Cantharellus cibarius (engl., chanterelle), Leccinum scabrum (engl., red birch boletus), Lentinus edodes (jap., Shiitake), and Pleurotus ostreatus (engl., oystermushroom), were isolated, and their chemical structures investigated. All glycolipids are structurally related to those of the Agaricales (engl., field mushroom). They are glycoinositolphosphosphingolipids, their ceramide moiety consisting of t18:0-trihydroxysphinganine and an alpha-hydroxy long-chain fatty acid. In contrast to a previous study [Jennemann, R., Bauer, B.L., Bertalanffy, H., Geyer, R., Gschwind, R.M., Selmer, T. & Wiegandt, H. (1999) Eur. J. Biochem. 259, 331--338], the glycoside anomery of the hexose (mannose) connected to the inositol of all investigated basidiomycete glycolipids, including the basidiolipids of Agaricus bisporus, was determined unequivocally to be alpha. Therefore, the root structure of all basidiolipids consists of alpha-DManp-2Ins1-[PO(4)]-Cer. In addition, for some mushroom species, the occurrence of an inositol substitution position variant, alpha-Manp-4Ins1-[PO(40]-Cer, is shown. The carbohydrate of chanterelle basidiolipids consists solely of mannose, i.e. Cc1, Man alpha-3 or -6Man alpha; Cc2, Man alpha-3(Man alpha-6)Man alpha-. All other species investigated show extension of the alpha-mannoside in the 6-position by beta-galactoside, which, in some instances, is alpha-fucosylated in 2-position (Fuc alpha-2)Gal beta-6Man alpha-. Further sugar chain elongation at the beta-galactoside may be in 3- and/or 6-position by alpha-galactoside, e.g. Ce4, Po2, Gal alpha-3-(Gal alpha-6)(Fuc alpha-2)Gal beta-6Man alpha-, whereas A. virosa, Av-3, has a more complex, highly alpha-fucosylated terminus, Gal alpha-3 (Fuc alpha-2)(Fuc alpha-6)Gal alpha-2(Gal alpha-3)Gal beta-6Man alpha-. L. edodes basidiolipids show further elongation by alpha-mannoside, e.g. Le3, Man alpha-2Man alpha-6Gal alpha-3(Fuc alpha-2)Gal beta-6Man alpha-, C. exipuliformis glycolipid by alpha-glucoside, i.e. Ce3, Glc alpha-6Gal beta-6Man alpha-. Basidiolipid Ls1 from L. scabrum, notably, has a 3-alpha-mannosylated alpha-fucose, i.e. Gal alpha-6(Man alpha-3Fuc alpha-2)Gal alpha-6Gal beta-6Man alpha-. In conclusion, basidiolipids, though identical in their ceramide constitution, display wide and systematic mushroom species dependent variabilities of their chemical structures.

Isolation and partial characterization of Fes p 4 allergen

More than 75% of grass pollen-allergic patients produce specific IgE antibodies against group-4 allergens. Purification and characterization of different grass group-4 allergens should help to further understand their allergenicity. In this study, an attempt was made to isolate and characterize Fes p 4 allergen by several biochemical and immunochemical methods. Fes p 4 was purified by a combination of chromatographic techniques (gel permeation and ion exchange chromatography). Isolated protein revealed four main spots at a molecular weight of 60 kDa and a pI ranging from 8.7 to 9.1. Eight sera were selected from patients with positive result of skin prick test to the mixture of grass pollen extracts. ELISA inhibition technique was used to study Fes p 4-specific IgE in the patients' sera. ELISA to Festuca pratensis was inhibited up to 80% by F. pratensis pollen extract and up to 48% by Fes p 4. 2D-PAGE-immunoblot was used to identify allergenic and antigenic components of Fes p 4 with patients' IgE and monoclonal antibodies (MABs). Three components of purified protein expressed IgE binding ability. Two MABs which recognized unrelated regions on Phl p 4, bound three components of Fes p 4. The role of the carbohydrate moiety in allergenicity was examined with individual patient sera by using periodate-treated Fes p 4. Six out of eight patients reduced IgE binding to periodate-treated allergen. Isolated Fes R 4 glycoprotein consisted of four components, three of which were allergenic, and share common epitopes specific for grass group-4 homologs. The results of periodate oxidation of Fes p 4 suggest that the carbohydrate moiety is involved in IgE binding.

The kinetics of periodate oxidation of carbohydrates: a calorimetric approach

A calorimetric approach is described for analysing the kinetics of periodate oxidation on a series of monosaccharidic substrates. Rate constants at several temperatures were calculated from the calorimetric decay curves that are proportional to the rate of conversion. Arrhenius plots provided the activation parameters for the various carbohydrates and a linear correlation was found between the values of enthalpy and entropy of activation. The dependence of the values of kinetic rates on stereochemistry is interpreted in terms of conformational probability of the reactive state. The suitability of the calorimetric method to track the kinetic process of slow reactions is emphasised, in particular its ability to monitor, directly and continuously, the course of the reaction.

Oxidation chemistry of 1,2-dehydro-N-acetyldopamines: direct evidence for the formation of 1,2-dehydro-N-acetyldopamine quinone

Two-electron oxidation of catecholamines either by phenol oxidase or by chemical oxidants such as sodium periodate produces their corresponding o-quinones as observable products. But, in the case of 1,2-dehydro-N-acetyldopamine, an important insect cuticular sclerotizing precursor, phenol oxidase catalyzed oxidation has been reported to generate a quinone methide analog as a transient, but first observable product. ¿Sugumaran, M., Semensi, V., Kalyanaraman, B., Bruce, J. M., and Land, E. J. (1992) J. Biol. Chem. 267, 10355-10361. The corresponding quinone has escaped detection until now. However, in this paper, for the first time, we present direct evidence for the formation of dehydro-N-acetyldopamine quinone and show that it can readily be produced from the tautomeric quinone methide imine amide during the chemical oxidation of dehydro-N-acetyldopamine under acidic conditions. This situation is in sharp contrast to other known alkyl-substituted catechol oxidations, where quinone is the first observable product and quinone methide is the subsequently generated product. Dehydro-N-acetyldopamine quinone thus formed is also highly unstable. Semiempirical molecular orbital calculation also indicates that quinone methide imine amide is more stable than the quinone. Chemical considerations indicate that the quinone methide tautomer, and not the dehydro-N-acetyldopamine quinone, is responsible for crosslinking the structural proteins and chitin polymer in the insect cuticle. Therefore, the quinone methide tautomer, and not the quinone, is the key reactive intermediate aiding the hardening of insect cuticle.

Schistosoma mansoni: immunodiagnosis is improved by sodium metaperiodate which reduces cross-reactivity due to glycosylated epitopes of soluble egg antigen

ELISA with soluble egg antigen (SEA) from Schistosoma mansoni is widely used in the diagnosis of schistosomiasis, but cross-reactivity with other intestinal helminths, overestimating the true prevalence, represents a great limitation. The role of glycoproteins of SEA in cross-reactions was investigated. SEA was oxidized with sodium metaperiodate (SMP) in ELISA and immunoblot. One hundred schistosomiasis-negative individuals sera were submitted to SMP-ELISA improving the specificity from 73% without SMP treatment to 97% with SMP. On the other hand, 94 S. mansoni-positive sera were evaluated showing that 99% were positive in ELISA either with or without SMP treatment, indicating the maintenance of high sensitivity under SMP treatment. By immunoblot, 24 sera from persons with schistosomiasis and 10 sera from schistosomiasis-free persons were assayed under reducing and nonreducing conditions with or without SMP, looking for specific infection markers and cross-reactivity markers. Reactivity from positive sera showed that specific molecules were mainly low-molecular-mass antigens and seem to have predominant proteic epitopes. The unspecific molecules reacting with some schistosomiasis-negative individuals harboring other intestinal parasites (false-positive sera) were mostly larger than 60 kDa and seemed to be basically glycosylated. Glycosylated epitopes have an important role in cross-reaction and SMP can successfully be used to reduce the false reactivity of SEA with no decrease in sensitivity, especially in ELISA as an immunodiagnostic screening surveillance method, which is useful in areas of low schistosomiasis transmission.

Protein A immobilization and HIgG adsorption onto porous/nonporous and swellable HEMA-incorporated polyEGDMA microspheres

Both non swellable and swellable poly(EGDMA/HEMA) microbeads were produced by suspension copolymerization. These microbeads were modified by immobilization of a spacer-arm (hexamethylene diamine (HMDA)) and protein A. The optimal values for modifications were as follows: sodium periodate concentration, 1.0 mgml(-1); HMDA concentration, 4 mgml(-1); and glutaraldehyde concentration, 0.070 microgml(-1). Adsorption of protein A onto the plain and periodate oxidized poly(EGDMA/HEMA) microbeads were very close to each other, and were 0.01-0.02 mg protein A on the 1-g Microbeads I and II, respectively. Protein A immobilization on poly(EGDMA/HEMA) microbeads were studied at different temperatures, times, and pHs using single protein solution containing different amounts of proteins. The optimal values for immobilization were as follows: the initial protein A concentration, 0.1 mgml(-1); temperature, 25 degrees C; pH, 9.5; and immobilization time, 120 min. Incorporation of protein A resulted in 1.420 and 1.825 mg protein A on the 1-g Microbeads I and II, respectively. HIgG adsorption capacity on the protein A-incorporated poly(EGDMA/HEMA) microbeads is 27 and 35 mg HIgGg(-1) polymer for Microbeads I and II, respectively.

Characterization of the cryptogein binding sites on plant plasma membranes

Cryptogein is a 98-amino acid proteinaceous elicitor of tobacco defense reactions. Specific binding of cryptogein to high affinity binding sites on tobacco plasma membranes has been previously reported (K(d) = 2 nM; number of binding sites: 220 fmol/mg of protein). In this study, biochemical characterization of cryptogein binding sites reveals that they correspond to a plasma membrane glycoprotein(s) with an N-linked carbohydrate moiety, which is involved in cryptogein binding. Radiation inactivation experiments performed on tobacco plasma membrane preparations indicated that cryptogein bound specifically to a plasma membrane component with an apparent functional molecular mass of 193 kDa. Moreover, using the homobifunctional cross-linking reagent disuccinimidyl suberate and tobacco plasma membranes incubated with (125)I-cryptogein, we identified, after SDS-polyacrylamide gel electrophoresis and autoradiography, two (125)I-cryptogein linked N-glycoproteins of about 162 and 50 kDa. Similar results were obtained using Arabidopsis thaliana and Acer pseudoplatanus plasma membrane preparations, whereas cryptogein did not induce any effects on the corresponding cell suspensions. These results suggest that either cryptogein binds to nonfunctional binding sites, homologues to those present in tobacco plasma membranes, or that a protein involved in signal transduction after cryptogein recognition is absent or inactive in both A. pseudoplatanus and A. thaliana.

Expression and functional characterization of bluetongue virus VP2 protein: role in cell entry

Segment 2 of bluetongue virus (BTV) serotype 10, which encodes the outer capsid protein VP2, was tagged with the S-peptide fragment of RNase A and expressed by a recombinant baculovirus. The recombinant protein was subsequently purified to homogeneity by virtue of the S tag, and the oligomeric nature of the purified protein was determined. The data obtained indicated that the majority of the protein forms a dimer and, to a lesser extent, some trimer. The recombinant protein was used to determine various biological functions of VP2. The purified VP2 was shown to have virus hemagglutinin activity and was antigenically indistinguishable from the VP2 of the virion. Whether VP2 is responsible for BTV entry into permissive cells was subsequently assessed by cell surface attachment and internalization studies with an immunofluorescence assay system. The results demonstrated that VP2 alone is responsible for virus entry into mammalian cells. By competition assay, it appeared that both VP2 and the BTV virion attached to the same cell surface molecule(s). The purified VP2 also had a strong affinity for binding to glycophorin A, a sialoglycoprotein component of erythrocytes, indicating that VP2 may be responsible for BTV transmission by the Culicoides vector to vertebrate hosts during blood feeding. Further, by various enzymatic treatments of BTV-permissive L929 cells, preliminary data have been obtained which indicated that the BTV receptor molecule(s) is likely to be a glycoprotein and that either the protein moiety of the glycoprotein or a second protein molecule could also serve as a coreceptor for BTV infection.