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Biomedical subjects

H Blobel

Publications and source records attributed to H Blobel.

At least 37 records · Page 2Linked to original sources
PubMed1989

Detection and interspecies-transformation of a beta-lactamase-encoding plasmid from Pasteurella haemolytica.

Pasteurella haemolytica-cultures, isolated from cattle with respiratory diseases, were investigated for their biotype, serotype, antimicrobial resistance and plasmid content. A plasmid encoding a beta-lactamase could be demonstrated in 9 of 19 Pasteurella haemolytica-cultures. These 9 cultures, all belonging to biotype A and serotype 1, were resistant to ampicillin, carbenicillin, penicillin G and ticarcillin. The plasmid of the respective cultures proved to be identical upon Southern blot hybridization. It could be transformed into Escherichia coli 490 A where it expressed again a beta-lactamase-activity.

Ampicillin Resistance↗
PubMed1989

Isolation and characterization of hyaluronidase from Streptococcus uberis.

All tested cultures of Streptococcus uberis produced free hyaluronidase. Hyaluronidase could be isolated by ammonium sulfate precipitation and was further purified by chromatography on DEAE-cellulose, gelfiltration on ultragel ACA44 and isoelectric focusing. The purification factor was estimated to be 1689. The purified hyaluronidase had an isoelectric point at pH 4.9 and a molecular weight of approximately 54000 D. It showed maximal enzyme activity at pH 6.0 and 45 degrees C. The Michaelis constant was estimated to be 7.0 X 10(-2) mg/ml. Hyaluronidase activity was stimulated by Ca++, Mg++, Mn++, Co++, Li+, and K+ and inhibited by Zn++ and Cd++ at final concentrations of 10 mmol/l, respectively.

Cations↗
PubMed1989

Plasmid-mediated chloramphenicol resistance in Staphylococcus hyicus.

A small plasmid of 3.95 kb, encoding resistance to chloramphenicol (Cm) was detected in three of 33 Staphylococcus hyicus strains. The plasmid in each of the three strains was indistinguishable by Southern-blot hybridization and restriction enzyme analysis. It was shown by curing and by transformation to specify resistance to Cm. A preliminary restriction map of the plasmid, designated pSC2, is presented. Chloramphenicol acetyltransferase was demonstrated by enzyme assay and by SDS-PAGE of cell-free lysates of pSC2 transformants.

Animals↗
PubMed1989

Plasmids and resistance to antimicrobial agents and heavy metals in Staphylococcus hyicus from pigs and cattle.

Staphylococcus hyicus-cultures, isolated from piglets and cattle with skin lesions were investigated for their plasmid content and their resistance to antimicrobial agents and heavy metals. Several plasmids of different sizes could be detected in most of the 32 "porcine" S. hyicus-isolates, whereas none of the 20 "bovine" S. hyicus-cultures possessed any plasmid. The "porcine" S. hyicus-isolates were much more resistant to antimicrobial substances than the "bovine" S. hyicus-cultures. However, the "porcine" and "bovine" S. hyicus-cultures did not differ in their resistance to heavy metals.

Animals↗
PubMed1988

Comparative studies on Actinomyces pyogenes and Arcanobacterium haemolyticum.

Actinomyces pyogenes and Arcanobacterium haemolyticum were further characterized. A. haemolyticum, in contrast to A. pyogenes, gave synergistic hemolytic reactions with streptococci of serological group B and inhibited staphylococcal beta-hemolysis. A. pyogenes and A. haemolyticum had a number of common, as well as distinctly different enzymatic properties, useful for their characterization. Extracts from A. pyogenes reacted with antiserum against streptococci of serological group G in contrast to those from A. haemolyticum.

Actinomyces↗
PubMed1988

Cytotoxic effects of a leukocidin from Fusobacterium necrophorum on bovine hepatic cells.

Cytotoxic effects of a leukocidin from Fusobacterium necrophorum were demonstrated on bovine hepatic cells. The cytotoxic response was dose-dependent and could be inhibited by homologous antiserum. Scanning electron microscopy revealed damaged hepatic cell surface. These findings indicated a pathogenic role of the leukocidin in F. necrophorum infections.

Animals↗
PubMed1988

Interactions of streptococci with human colostral immunoglobulin A.

Streptococci of serological groups A, B, C, G and L were examined for interactions with human colostral IgA. Of 28 A-streptococcal cultures, 12 bound IgA with a mean of 38.7%. The other streptococci had little or no IgA-binding activities. Of the 12 IgA-binding A-streptococcal cultures, 8 contained the M-protein M 4 and 2 the M-protein M 60. The specific binding sites for IgA were heat-sensitive (60 min, 80 degrees C) and susceptible to trypsin and pronase.

Animals↗
PubMed1988

Effects of leukocidin from Fusobacterium necrophorum on bovine peripheral leukocytes in vitro.

Partially purified leukocidin from Fusobacterium necrophorum damaged bovine peripheral leukocytes as demonstrated by trypan blue staining. Granulocytes were most and T-lymphocytes least sensitive to the leukocidin. Heating for 30 min at 60 degrees C completely inactivated the leukocidin. The cytotoxicity of the leukocidin could be neutralized by homologous anti-leukocidin. Scanning electron microscopy of the exposed cells revealed an apparent destruction of the cell membranes, loss of the microvilli and smoothing of the cell surfaces.

Animals↗
PubMed1988

Binding activity of Streptococcus canis for albumin and other plasma proteins.

All 24 cultures of Streptococcus canis examined bound 125I-labelled human albumin, IgG and fibrinogen; but neither IgA nor haptoglobin. Binding of human albumin was time-dependent, saturable and reversible by the addition of unlabelled albumin. The binding of 125I-labelled human albumin could be inhibited completely by unlabelled albumin preparations from humans, mice and dogs, and partly by bovine albumin. In contrast, binding of 125I-labelled human albumin was not inhibited by unlabelled rabbit albumin, human IgG or human fibrinogen. Data from competition experiments of two S. canis cultures with high 125I-labelled albumin-binding activities yielded KD values of 10 and 15 nmol l-1, respectively. The estimated number of binding sites per bacterial cell ranged from 30,000 to 57,000. The binding factor for albumin could be isolated from S. canis by boiling the bacteria at pH 2, and it was purified by affinity chromatography on human albumin-Sepharose. The isolated albumin-binding proteins had a molecular mass of approximately 51 kDa and inhibited binding of 125I-labelled albumin to S. canis. They formed complexes with human albumin that altered its electrophoretic mobility.

Albumins↗
PubMed1988

Mediation of adherence of streptococci to human endothelial cells by complement S protein (vitronectin).

The role of S protein in the adherence of group A and G streptococci to human umbilical vein endothelial cells cultivated in 96-well microdilution plates was studied by utilizing fluorescein-labeled streptococci. The assay proved suitable for quantitative determination of bacterial adherence to cultured endothelial cells for all tested strains of streptococci. Only bacterial strains with significant S protein binding but weak fibronectin binding were included in these studies. Fibronectin-mediated adherence to endothelial cells of these streptococci was less than 25% of total and could be blocked by antifibronectin immunoglobulin G. Further treatment of endothelial cell monolayers with anti-S protein immunoglobulin G at concentrations up to 1 mg per well led to an almost complete inhibition of adherence for all tested streptococcal cultures, indicating significant contribution of S protein in the streptococcus-endothelial cell interaction. Blocking of S-protein-binding sites on streptococci by preincubation with exogeneous S protein at a concentration of 10 micrograms per 4 x 10(7) streptococci led to about 75% reduction of S-protein-mediated adherence to endothelial cells. Trypsin pretreatment of group G streptococci and pronase pretreatment of group A and G streptococci, modifications known to destroy the bacterial binding sites of S protein, also inhibited the capacity of the streptococci for S-protein-mediated adherence to endothelial cells by 75 to 80%. These results indicate that S protein plays a mediatory role in adherence of streptococci to endothelial cells and that S-protein-specific binding sites on streptococci are involved in this interaction.

Bacterial Adhesion↗
PubMed1988

Bindings of plasma proteins to streptococci of serological group L with special reference to their immunoglobulin G Fc-receptor activity.

Of 33 streptococcal cultures belonging to serological group L, all bound human immunoglobulin (Ig) G, fibrinogen, and fibronectin; 32 bound bovine IgG; 31 bound alpha 2-macroglobulin; 5 bound albumin; and none bound either haptoglobin or IgA. The binding sites for IgG could be isolated from the L streptococci by trypsinization and purified by affinity chromatography on human IgG-Sepharose. The purified Fc receptors reacted with IgG subclasses 1, 2, 3, 4 of humans, 1 and 2 of bovines, ovines, and caprines as well as a, b, c, and T of equines. They had a molecular mass of approximately 49,000 Da. Thus, the Fc receptors from L streptococci corresponded to type III Fc receptors of Streptococcus dysgalactiae.

Animals↗
PubMed1988

Adherence of streptococcal isolates from cattle and horses to their respective host epithelial cells.

Adherence of Streptococcus dysgalactiae isolates from cattle and S equi isolates from horses to their respective host epithelial cells was compared with the adherence of S pyogenes to human epithelial cells. The adherence was quantitatively determined by use of fluorescein-labeled streptococci. All 3 streptococcal species adhered selectively to their respective host cells. The mechanism of adherence was evaluated by binding studies with adhesive plasma protein, fibronectin. Although all 3 streptococcal species bound fibronectin, S dysgalactiae and S equi interacted preferentially with a 210-kilodalton (kD) C-terminal fragment of fibronectin, whereas S pyogenes bound only a 29-kD N-terminal fragment. A synthetic peptide Gly-Arg-Gly-Asp-Ser, representing the host cell attachment site of fibronectin, partially inhibited the binding of fibronectin and of its 210 kD fragment to S dysgalactiae, but not to S equi. The binding of fibronectin and its 29-kD fragment to S pyogenes was not inhibited by Gly-Arg-Gly-Asp-Ser. These differences in binding activities corresponded to the ability of fibronectin to mediate the adherence of the streptococci to the epithelial cells: fibronectin strongly inhibited the adherence of S pyogenes and S equi to the epithelial cells, but only weakly inhibited that of S dysgalactiae.

Animals↗
PubMed1987

Isolation and properties of a novel IgG-binding protein from streptococci of serological group U.

A nonimmune binding of immunoglobulin (Ig) G has been detected in streptococci of group U. The group U Fc-binding site differed from the five previously known types of staphylococcal and streptococcal Fc-binding sites by its strong affinity for murine IgG, with dissociation constants in nanomolar range for rat and mouse IgG, as well as for mouse IgG subclasses 1, 2a, 2b and 3. It also differed from other binding sites by the high sensitivity towards trypsin. The Fc-binding protein could be solubilized from the streptococci of group U with papain and purified by gel filtration on sephacryl S-200 and by subsequent affinity chromatography on human IgG-Sepharose. The purified binding protein was homogeneous on SDS-polyacrylamide gel electrophoresis and had a molecular weight of approximately 58,000 daltons. It retained its binding activities for murine IgG subclasses as revealed by western blotting. Coupled to CNBr-activated sepharose, the purified Fc-binding protein could be effectively used for the isolation of murine IgG subclasses by affinity chromatography.

Animals↗
PubMed1987

Properties of L-streptococci in comparison with those of A-streptococci.

Despite some similarities, L-streptococci could be clearly differentiated from A-streptococci. Formamide, autoclaved and nitrous acid extracts of all L-streptococcal cultures studied reacted only with their specific antisera and did not cross-react with any other group specific streptococcal antigens. All 33 L-streptococcal cultures, in contrast to A-streptococci, produced beta-D-glucuronidase and beta-D-galactosidase, hydrolyzed Na-hippurate, grew on 10% and 40% bile blood agar and were agglutinated by the lectin of Arachis hypogaea. Some differences between A- and L-streptococci were also observed in their sensitivity patterns to bacitracin and sulfamethoxazole-trimethoprim.

Agglutination↗
PubMed1987

Heterogeneity of fibronectin reactivity among streptococci as revealed by binding of fibronectin fragments.

Streptococci belonging to serological groups A, B, C, G, L and U were studied for their interaction with 125I-labelled fibronectin and its fragments. Fibronectin purified from humans plasma by affinity chromatography on gelatin-agarose and heparin-agarose was cleaved by thrombin into a 29,000 Dalton and a 210,000 Dalton fragments. Terminal analysis of purified fragments indicated that 29,000 fragment was from amino-terminal and 210,000 fragment from carboxyl-terminal domain of fibronectin. Binding of fibronectin was observed in all streptococci except those of group B. Streptococci of groups A, G, L, U and S. equisimilis reacted only with 29,000 Dalton fragment whereas S. dysgalactiae, S. zooepidermicus and S. equi reacted only with 210,000 Dalton fragment. The streptococcal binding sites for these two fragments were distinct from each other. Fibrinogen blocked the binding of 210,000 Dalton fragment but not of 29,000 Dalton fragment. Trypsinization of streptococci did not affect their binding sites for 210,000 Dalton fragment but destroyed those for 29,000 Dalton fragment. The results indicate that the streptococci of group A and G as well as S. equisimilis which are mainly pathogenic in humans bind amino-terminal fragment of fibronectin. This may facilitate the adherence of these pathogens. On the other hand, the streptococci isolated from animal infections had different binding sites recognized only by carboxyl-terminal part of fibronectin.

Binding Sites↗
PubMed1987

Isolation and characterization of a staphylococcal enzyme bacteriolytic on streptococci.

Staphylococcus hyicus, strain CCM 2368, produced a bacteriolytic enzyme, highly effective on streptococci, some staphylococci and micrococci. Production of the enzyme increased significantly following addition of NaCl (at 1.5%) to the growth medium. The bacteriolytic enzyme could be precipitated from the cell-free staphylococcal culture supernatant with ammonium sulfate at 60% saturation and partially purified by DEAE chromatography. Subsequent isoelectric focusing resulted in complete removal of proteolytic activity and revealed 2 bacteriolytic fractions. One of these (LE IIIa) had an isoelectric point near pH 9.8, the other (LE IIIb) near pH 10.3. LE IIIa lyzed more effectively streptococcal and LE IIIb micrococcal test cells. HPLC gel permeation chromatography also yielded 2 bacteriolytic fractions. The isolated staphylococcal enzyme appeared to be suitable for lysis of streptococci and solubilization of their cell wall structures.

Bacteriolysis↗