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At least 865 records · Page 48Linked to original sources
PubMed2001

Pectin: cell biology and prospects for functional analysis.

Pectin is a major component of primary cell walls of all land plants and encompasses a range of galacturonic acid-rich polysaccharides. Three major pectic polysaccharides (homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II) are thought to occur in all primary cell walls. This review surveys what is known about the structure and function of these pectin domains. The high degree of structural complexity and heterogeneity of the pectic matrix is produced both during biosynthesis in the endomembrane system and as a result of the action of an array of wall-based pectin-modifying enzymes. Recent developments in analytical techniques and in the generation of anti-pectin probes have begun to place the structural complexity of pectin in cell biological and developmental contexts. The in muro de-methyl-esterification of homogalacturonan by pectin methyl esterases is emerging as a key process for the local modulation of matrix properties. Rhamnogalacturonan-I comprises a highly diverse population of spatially and developmentally regulated polymers, whereas rhamnogalacturonan-II appears to be a highly conserved and stable pectic domain. Current knowledge of biosynthetic enzymes, plant and microbial pectinases and the interactions of pectin with other cell wall components and the impact of molecular genetic approaches are reviewed in terms of the functional analysis of pectic polysaccharides in plant growth and development.

Cell Wall↗
PubMed2000

Intraradicular space: what happens within roots of infected teeth?

The pulpo-dentine complex is normally protected from exogenous substances in the oral cavity by the overlying enamel or cementum. Dental caries, dental trauma, enamel/dentine cracks, and restorative procedures commonly breach the integrity of enamel or cementum and may allow infection of the pulpo-dentine complex to occur, possibly leading to pulp and periapical inflammatory disease. Infection of the intraradicular space is a complex and dynamic process involving interactions between host and microbial factors. An understanding of these factors has led to the development of endodontic techniques that offer predictable success.

Dental Caries↗
PubMed2004

[Usefulness of the E-test and its assay conditions in the study of the interaction of antifungal agents. A pilot study].

Preliminary data from a pilot study to assess the usefulness of the E-test in the study of antimycoctics are presented, evaluating assay and reproduction conditions. Results are compared with those obtained using the checkerboard method and mortality-time curves. Trials were carried out with a strain of Candida albicans (ATCC 90028). The E-test strips were combined in direct proportion, MIC-MIC, and in inverse proportion. The results showed that the method can be reproduced, is easy to carry out and may be suitable for the study of the in vitro interaction of antimycotics on yeast. The directly and inversely proportionate strip combination appeared to be the most suitable. At the prediffusion stage, the most highly water-soluble antimycotic should be used. The recommended time for prediffusion is one hour for water-soluble antimycotics, and two hours for non-water-soluble ones. The E-test showed good correlation with mortality-time curves. Nonetheless, in vivo correlation studies are required to determine the usefulness of the results in vitro and the most suitable method of measurement

Amphotericin B↗
PubMedDate not supplied

[Substrate specificity of collagenase of Streptomyces sp. 1349 and keratinase of Streptomyces sp. 1382].

The paper determines the action specificity concerning the bonding type of collagenases of Strepomyces sp. 1349 and keratinases of Streptomyces sp. 1382. Experimental data obtained evidence for the wide specificity of the obtained enzymatic drugs. It has been established that both collagenases and keratinases display high specificity in respect of the bonds made by the residues of hydrophobic amino acids. Collagenases of Streptomyces sp. 1349, as to their wide action specificity, differed from collagenase of Clostridium histolyticum described in literature, that was confirmed by the results of double immunodiffusion in agar by Ouchterloni. Preparations of streptomycete collagenase obtained by the authors did not interact with serum obtained for highly purified collagenase of C. histolyticum of the firm "Merck". Investigation of the feather keratin lysates by the fractions of keratinases 1 and 2 have shown the difference in the content of amino acids released after hydrolysis that may be determined by different specificity of the enzymes action. Cysteine in the amount of 3.8% was also found in keratin lysate of the enzymatic fraction 1, that may evidence for the capacity of the fraction 1 to break the disulphide bonds in keratin molecule.

Amino Acids↗
PubMedDate not supplied

Mannose-binding lectin enhances the attachment and phagocytosis of mycobacteria in vitro.

INTRODUCTION: Phagocytosis is the critical first step in the Mycobacterium (M.) tuberculosis-phagocyte interaction. The process involves microbial ligands and phagocyte surface receptors. It is known that serum mannose-binding lectin (MBL), an innate immune system component, may enhance the uptake of microbes by phagocytic cells and activate the complement system. Since phagocytes are the replicative environment for mycobacteria and, as we described earlier, tuberculosis patients differ from controls in serum MBL level, we asked whether MBL plays a role in promoting M. tuberculosis access to phagocytic cells. MATERIAL/METHODS: To estimate the influence of MBL on the phagocytic process, FITC-labeled Mycobacterium bovis BCG was used as a model bacterium. Neutrophils from healthy individuals were used as phagocytes. Phagocytosis was performed in the presence or absence of recombinant MBL (rMBL; 2 or 20 microg/ml). The activation of complement was determined by dot-blot immune assay with monoclonal antibodies against C5b-C9. RESULTS: We showed that phagocytosis of the bacteria was more intensive in the presence of human rMBL. Both attachment and ingestion of mycobacteria were enhanced when MBL and active complement components (fresh serum) were present in the medium. The dot-blot method showed that the bacteria slightly activated complement by themselves. This effect was enhanced in the phagocyte-bacteria co-cultures containing rMBL. CONCLUSIONS: It is possible that MBL may serve in vivo as one of the factors facilitating the entry of mycobacteria into phagocytes, pathogen spread, and the establishment of infection.

Bacterial Adhesion↗
PubMed2005

Slime-producing Staphylococcus epidermidis and S. aureus in acute bacterial conjunctivitis in soft contact lens wearers.

In recent years, an increase in ocular pathologies related to soft contact lens has been observed. The most common infectious agents were Staphylococcus spp. Some strains produce an extracellular polysaccharidic slime that can cause severe infections. Polysaccharide synthesis is under genetic control and involves a specific intercellular adhesion (ica) locus, in particular, icaA and icaD genes. Conjunctival swabs from 97 patients with presumably bacterial bilateral conjunctivitis, wearers of soft contact lenses were examined. We determined the ability of staphylococci to produce slime, relating it to the presence of icaA and icaD genes. We also investigated the antibiotic susceptibility and Pulsed Field Gel Electrophoresis (PFGE) patterns of the clinical isolates. We found that 74.1% of the S. epidermidis strains and 61.1% of the S. aureus strains isolated were slime producers and showed icaA and icaD genes. Both S. epidermidis and S. aureus slime-producing strains exhibited more surface hydrophobicity than non-producing slime strains. The PFGE patterns overlapped in S. epidermidis strains with high hydrophobicity. The similar PFGE patterns were not related to biofilm production. We found scarce matching among the Staphylococcus spp. studied, slime production, surface hydrophobicity and antibiotic susceptibility.

Adolescent↗
PubMed1991

A comparative study of the activity of first and second generation cephalosporins and their combinations with beta-lactamase inhibitors against Bacteroides fragilis.

The sensitivity of 160 strains of Bacteroides fragilis, 74 beta-lactamase-positive and 86 negative, to two first generation and four second generation cephalosporins, alone and in combination with clavulanic acid and sulbactam, was investigated. For the susceptibility test the dilution method in agar was used. The detection of beta-lactamase production by this micro-organism was performed by means of the method using chromogenic cephalosporin of Nitrocefin. In both strains an important improvement in the activity of cephalothin, cephazolin, cefonicid and cefamandole was noted when they were combined with the two inhibitors. In combinations of cefoxitin and cefmetazole, no significant improvement was evident in the values of the parameters studied in the beta-lactamase-producing strains; and even in beta-lactamase-negative strains these values showed only a slight increase.

Bacteroides fragilis↗
PubMed1988

Subtilisin inhibitors in legume seeds.

Subtilisin inhibitors (SI) having an average molecular mass of 8 kDa purified from jack beans (Canavalia ensiformis) and broad beans (Vicia faba) to electrophoretical homogeneity are compared to those isolated from chick peas (Cicer arietinum) and black beans (Phaseolus vulgaris). The specificity spectrum of SI is restricted to microbial serine proteinases. Their interaction with subtilisin Carlsberg is variable, obtaining the highest value for black bean, followed by broad bean, chick pea and jack bean inhibitors. Proteinase K reacts with most SI twice as strongly as subtilisin. The reaction of SI with subtilisin apparently follows the "standard mechanism" proposed by Laskowski for the interaction of trypsin with its inhibitors. Accordingly, the reactive site of jack bean, broad bean and black bean SI is reversibly cleaved by subtilisin in acid and neutral solutions, whereas chick pea SI is hydrolysed only at neutral pH values. Judged by similarities in specificity, molecular mass, heat stability and reactive site cleavage, the SI from legume seeds could constitute a new "family" of proteinase inhibitors.

Binding Sites↗
PubMed1979

[Bactericidal activity "in vitro" of sulfamethoxazol-tri-methoprime (SMZ-TMP) alone and in combination with various antibiotics on bacterial strains isolated from urinary tract infections (author's transl)].

The authors study "in vitro" effects of sulfamethoxazol-trimethroprime (SMZ-TMP) on 1 078 bacterial strains isolated from urinary-tract infections during january 1974, the second trimester 1974 and january 1975. Study involves two parts : comparison between bacteriostatic activity of SMZ-TMP, ampicillin and nalidixic acid; evaluation of bactericidal activity of antibiotic associations including SMZ-TMP. MIC study included all strains. On Gram- negative bacilli the bacteriostatic activity of SMZ-TMP (74,6 percent of sensitive strains) was comparable with nalidixic acid (79,6 percent of sensitive strains) and better than ampicillin 31,4 percent of sensitive strains). On staphylococcus strains the bacteriostatic activity of SMZ-TMP (84,6 percent of sensitive strains) is better than ampicillin (36,4 percent of sensitive strains); on streptococcus strains the bacteriostatic activity of ampicillin (71 percent of sensitive strains) is better than SMZ-TMP (5l percent of sensitive strains). 473 associations including SMZ-TMP were studied upon 44 strains of Gram- negative bacilli by bactericidal test. ("Cross disposition" method, derive from "cellophane transfer method".

Ampicillin↗
PubMed1984

[Microbiological aspects of the elaboration of effective antibiotic therapy of bacterial lesions of the biliary tract].

Sensitivity of staphylococci of different origin to desoxycholic, cholic and choleic bile acids was studied. On this basis a system for differentiation of the staphylococcal bilicultures from the staphylococcal cultures of the other origin was developed. It was shown that the bile and bile acids potentiated the activity of some antibiotics and inhibited the action of the others. Such a strictly individual property of synergism or antagonism of the cholates and antibiotics depended on the properties of the causative agent and the type of the antibiotics and bile acids. The results of the study provided the development of a method for determination of the biliculture antibiotic sensitivity on a medium containing the patient's bile. The antibiotic which induced the maximum inhibition of the bacterial growth in the presence of the patient's bile should be recommended for the treatment of this patient.

Anti-Bacterial Agents↗
PubMed1982

Gastrointestinal mucins. Structures and antigenicities of their carbohydrate chains in health and disease.

The carbohydrate chains of gastrointestinal mucins are of wide interest because the same structures occur on glycoproteins and glycolipids of cell membranes and they express a variety of antigens recognized by polyclonal and monoclonal antibodies. In this article we summarize the information available on the structures found in three domains ('peripheral', 'backbone' and 'core' regions) of the carbohydrate chains of mucins. We discuss the various antigens expressed on these domains and the changes in their expression in benign and malignant diseases of the gastrointestinal tract. These antigens include the major blood group antigens A, B, H, Lea and Leb, the Ii antigens and some hybridoma-defined antigens termed SSEA-1, VEP8/9 and FC 10.2, all of which are now regarded as differentiation antigens with changing expression during embryogenesis and stages of cell differentiation. The functions of these diverse carbohydrate chains have eluded us thus far; they deserve systematic investigation as possible receptors involved in cellular interactions and reactions with microbial agents.

Antigens, Neoplasm↗
PubMed1980

In vitro investigations on the action fosfomycin alone and in combination with other antibiotics on Pseudomonas aeruginosa and Serratia marcescens.

86.4% of the Pseudomonas aeruginosa and 91% of the Serratia marcescens strains were sensitive to fosfomycin. In combination with mezlocillin, cefoxitin, gentamicin and nalidixic acid a synergistic action was detected against these bacterial strains. It was most marked in the combination fosfomycin/nalidixic acid against Serratia marcescens. An acceleration of the fosfomycin action on the bacterial cells and the speed of bacteriolysis was observed in weakly acid medium (pH 6.0), in the presence of 10% active human serum and with increasing glucose-6-phosphate concentrations in the test medium. There is no parallel resistance between gentamicin and fosfomycin against Pseudomonas aeruginosa.

Anti-Bacterial Agents↗
PubMed1975

[Bacteriological studies on the therapy of bacillus pyocyaneus infections].

The effect of combined antibiotics was studied in 25 strains of Pseudomonas aeruginosa by serial diluting tests. A synergistic effect was stated in 15 strains with oxacillin plus ampicillin, and in 7 strains with carbenicillin plus ampicillin. In these examinations, the quantities of antibiotics needed each time were within the highest admissible level of therapuetic concentrations. A constant rate of the optimum single concentrations could not be observed. On principle, the inhibitory tobramycin concentrations (0.06 - 1 gamma/ml) were lower than the corresponding concentrations of gentamycin (0.25 - 2gamma/ml); tobramycin was more effective than gentamycin also in 6 strains resistant to carbenicillin, tobramycin only had a synergistic effect - in five of these six strains - when very high ampicillin concentrations (i.e. 250-500 gamma/ml) were used.

Ampicillin↗
PubMed1993

Osteopontin: a protein with diverse functions.

In this review most of the various known, suspected, or postulated functions of osteopontin, a secreted highly acidic phosphoprotein, are discussed in terms of what we currently know about the protein. These include 1) binding of OPN both to cells via a GRGDS cell adhesion sequence that recognizes the alpha v beta 3 integrin and to extracellular matrix components via poorly characterized motifs, 2) regulation of the formation and remodeling of mineralized tissue, 3) recruiting and stimulating macrophages and lymphocytes as part of a nonspecific response to microbial infections, 4) multiple interactions with Ca2+ that likely influence OPN protein conformation and may be important in Ca(2+)-mediated or Ca(2+)-dependent processes, 5) inhibiting the growth of calcium oxalate crystals by disruption of the growing crystal lattice, 6) effects on gene expression, Ca2+ regulation, and nitric oxide production, and 7) involvement in cell migration. OPN production is frequently augmented when cell signaling pathways are activated by any of a variety of stimuli, for example in cancer cells.

Amino Acid Sequence↗