Search PubMed⌕ Search

Biomedical subjects

D Mirelman

Publications and source records attributed to D Mirelman.

At least 127 records · Page 7Linked to original sources
PubMed1980

Improved filtration technique for concentrating and harvesting bacteria.

An improved technique is described for the filtrative concentration and harvesting of bacterial cultures. A pleated tangential flow filtration unit containing 1,000 cm of 0.2-mum-pore-size microporous membrane was used to rapidly (30 to 50 min) reduce the volume of 5 liters of bacterial culture of approximately 10 cells per ml to 0.2 to 0.5 liters of concentrated bacterial suspension. The effects of cell concentration, filtration pressure, and tangential flow rate were examined with respect to the rate of concentration and cell viability. Recovery efficiencies were between 60 and 75%, with no apparent impairment of organism viability. Cell concentration exerted the predominant effect on the filtration rate.

Journal Article↗
PubMed1980

Lectin activity in Entamoeba histolytica trophozoites.

A lectin (carbohydrate-binding protein) has been found in extracts of a number of axenically grown trophozoites of Entamoeba histolytica strains. The strains grown in TYI-S-33 medium (Diamond et al., Trans. R. Soc. Trop. Med. Hyg. 72: 431-432, 1978) were HK-9, 200:NIH, and HM-1:IMSS. Strain HU-1:MUSC (HSC) was grown monoxenically in the same medium. The amoebic lectin agglutinated glutaraldehyde-fixed erythrocytes. This activity was pH dependent and heat and oxidation sensitive, and was destroyed by proteolysis upon autoincubation. The relative agglutinating potency of the different strains of amoebae was investigated. Strain HSC had the highest specific activity (210 U/mg of protein), and strain HM-1 had the lowest (14 U/mg). One unit of hemagglutinating activity is defined as the amount of lectin present in 1 ml of extract which will agglutinate 1 ml of 4% erythrocytes. Upon subcellular fractionation of the lectin present in extracts of strain HK-9, two-thirds of the activity was detected in the soluble, nonsedimentable (100,000 x g, 60 min) fraction. Partial hydrolysate of chitin was found to inhibit the hemagglutinating activity. Among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors. The lectin was purified approximately 300-fold by a one-step affinity chromatography on a chitin column. The loading and elution from the column were based on the pH dependence of the lectin activity.

Agglutinins↗
PubMed1980

Mannose-binding activity of Escherichia coli: a determinant of attachment and ingestion of the bacteria by macrophages.

Recently, it was suggested that a mannose-specific lectin on the bacterial cell surface is responsible for the recognition by phagocytic cells of certain nonopsonized Escherichia coli strains. In this study we assessed the interaction of two strains of E. coli at different phases of growth with a monolayer of mouse peritoneal macrophages and developed a direct method with [(14)C]mannan to quantitate the bacterial mannose-binding activity. Normal-sized bacteria were obtained from logarithmic and stationary phases of growth. Nonseptated filamentous cells were formed by growing the organisms in the presence of cephalexin or at a restrictive temperature. Attachment to macrophages of all bacterial forms was inhibited by methyl alpha-d-mannoside and mannan but not by other sugars tested. The attachment of stationary phase and filamentous bacteria to macrophages, as well as their mannose-binding activity, was similar, whereas in the exponential-phase bacteria they were markedly reduced. The results show a linear relation between the two parameters (R = 0.98, P < 0.001). The internalization of the filamentous cells attached to macrophages during 45 min of incubation was much less efficient (20%) compared to that of exponential-phase, stationary-phase, or antibody-coated filamentous bacteria (90%). The results indicate that the mannose-binding activity of E. coli determines the recognition of the organisms by phagocytes. They further suggest that administration of beta-lactam antibiotics may impair elimination of certain pathogenic bacteria by inducing the formation of filaments which are inefficiently internalized by the host's phagocytic cells.

Animals↗
PubMed1980

Screening of bacterial isolates for mannose-specific lectin activity by agglutination of yeasts.

A total of 393 clinical bacterial isolates were tested for their ability to agglutinate yeast cells of either Saccharomyces cerevisiae or Candida albicans. A positive agglutination of yeasts that could be prevented by methyl alpha-D-mannoside was taken as an indication for the possible presence of a mannose-specific lectin (carbohydrate-binding protein) on the surface of the tested bacteria. Agglutination tests on glass slides showed that 38% of all the isolates tested were positive in their capacity to agglutinate yeasts. Among the various strains tested, all isolates of Serratia marcescens, Proteus morganii, and Citrobacter diversus, as well as 94% of Klebsiella pneumoniae, were positive. On the other hand, only 46% of the Escherichia coli, 48% of the salmonellae, 44% of the Citrobacter freundii, and 71% of the Aeromonas hydrophila isolates were positive. A quantitative determination of the lectin activity done by observing the agglutination of yeasts in microtiter plates showed that S. marcescens isolates were the most avid binders to the yeast, whereas Klebsiella and Citrobacter isolates were the weakest.

Agglutination↗
PubMed1980

A lectin activity in Entamoeba histolytica trophozoites.

A lectin (carbohydrate binding protein) has been found in extracts of a number of axenically grown trophozoites of Entamoeba histolytica strains. The strains grown in Diamond's TYI-S-33 media were HK-9, 200:NIH and HM-1: IMSS. Strain HU-1: MUSC (HSC) was grown monoxenically in the same medium. The amoeba lectin agglutinates glutaraldehyde-fixed red blood cells. This activity is pH dependent, heat and oxidation sensitive and is destroyed by proteolysis upon auto-incubation. The relative agglutinating potency of the different strains was investigated. Strain HSC had the highest specific activity (210 units/mg protein) and strain HM-1 the lowest (14 units/mg). One unit of haemagglutinating activity is defined as the amount of leetin present in 1 ml of extract which will agglutinate 1 ml of 4 per cent red blood cells. Upon subcellular fractionation of the lectin present in extracts of strain HK-9, two thirds of the activity were detected in the soluble, non-sedimentable (100,000 x g, 60 min) fraction. Partial hydrolysate of chitin was found to inhibit the haemagglutinating activity. Among the oligosaccharides of N-acetylglucosamine, the trimer and tetramer were the most potent inhibitors. The lectin was purified approximately 300 fold by a one step affinity chromatography on a chitin column. The loading and elution from the column were based on the pH dependence of the lectin activity.

Entamoeba histolytica↗
PubMed1979

Oxidative deamination of epsilon-aminolysine residues and formation of Schiff base cross-linkages in cell envelopes of Escherichia coli.

Oxidative deamination of the epsilon-amino group of lysyl residues to form allysine is the initial reaction in the cross-linking of collagen and elastin in vertebrates. The allysyl residues, generated by lysyl oxidase in this reaction, condense with either other allysyl residues or epsilon-amino groups of lysyl or hydroxylysyl to form aldol or Schiff base cross-links. This paper presents evidence that similar allysyl residues and Schiff base cross-links are synthesized in cell envelopes of Escherichia coli. Acid hydrolysis followed by amino acid analysis of envelopes either reduced with NaB[3H]4 or labeled with [14C]lysine and reduced with NaBH4 yielded allysine and two labeled fragments with elution profiles and molecular weights (250 and 330) consistent with Schiff base products derived at least in part from allysine. When [6-3H]lysine-labeled cell envelopes were incubated at 37 degrees C, gradual release of tritiated water occurred. This suggests that an enzymatic reaction catalyzes the deamination of lysine in E. coli membranes and that the higher molecular weight proteins detected in stationary phase or in log phase cell envelopes after NaBH4 reduction occur as a result of formation of Schiff base cross-links.

Amines↗
PubMed1979

Prevention of colonization of the urinary tract of mice with Escherichia coli by blocking of bacterial adherence with methyl alpha-D-mannopyranoside.

Methyl alpha-D-mannopyranoside (alpha MM), a competitor inhibitor of the binding of mannose by Escherichia coli, was tested for its ability to prevent infection of the urinary tract of mice with infective strains of the organisms. Injection of the bacteria in the presence of the drug resulted in a considerable reduction in the number of bacteriuric mice. In this system alpha MM was inactive against Proteus mirabilis in accordance with its inability to inhibit the adherence of this organism to epithelial cells in vitro, and methyl alpha-D-glucopyranoside proved inactive against both E. coli and P. mirabilis.

Adhesiveness↗
PubMed1979

Biosynthesis of peptidoglycan in Pseudomonas aeruginosa. 1. The incorporation of peptidoglycan into the cell wall.

Ether-treated cells of Pseudomonas aeruginosa catalyze the formation of crosslinked peptidoglycan from the two nucleotide precursors uridinediphospho-N-acetylglucosamine and uridinediphospho-N-acetylmuramyl-L-alanyl-D-gamma-glutamyl-meso-diaminopimelyl-D-alanyl-D-alanine. The main enzymatic reactions of biosynthesis were similar to those found in Escherichia coli. Part of the reaction products were soluble in 4% sodium dodecylsulfate whereas the other part was covalently bound to the preexisting cell wall peptidoglycan sacculus. The incorporation into cell wall is carried out by a transpeptidation reaction in which the nascent peptidoglycan functions mainly as the donor and the preexisting one as acceptor. The detergent-soluble peptidoglycan is composed of partially crosslinked peptidoglycan strands as well as low-molecular-weight peptidoglycan fragments. Pulse-chase biosynthesis experiments show that the detergent-soluble peptidoglycan is an intermediate that eventually becomes covalently bound to the wall. The DD-carboxypeptidase activity of P. aeruginosa is membrane-bound and does not hydrolyse C-terminal D-alanine residues from the L-lysine-containing nucleotide-precursor analogue. An LD-carboxypeptidase was also detected in P. aeruginosa.

Cell Wall↗
PubMed1979

Biosynthesis of peptidoglycan in Pseudomonas aeruginosa. 2. Mode of action of beta-lactam antibiotics.

The intrinsic effect of various beta-lactam antibiotics on the biosynthesis of peptidoglycan of Pseudomonas aeruginosa X-48 was investigated. Most of the cephalosporins and penicillins tested already at 0.5 microgram/ml strongly inhibited (a) the incorporation of nascent peptidoglycan into the detergent-insoluble fraction (greater than 75%), (b) the formation of peptide crosslinkages (greater than 60%) and (c) the activity of the DD-carboxypeptidase and partially that of the transpeptidase (approximately 90% and approximately 40% respectively). Another group of beta-lactum drugs did not inhibit incorporation into the material insoluble in sodium dodecylsulfate, the formation of peptide crosslinkages nor transpeptidase activity. They only partially inhibited the activity of the DD-carboxypeptidase--endopeptidase system (40--50% at 0.5 microgram/ml). The results obtained differ from those of Presslitz and Ray [Antimicrob, Agents Chemother. 7, 578--581 (1975)] and show some resemblance to the effects of beta-lactams on the biosynthesis of Escherichia coli peptidoglycan.

Acetylglucosamine↗
PubMed1978

Studies on growth inhibition by lectins of Penicillia and Aspergilli.

It has previously been shown in our laboratory that wheat germ agglutinin (WGA) binds to Trichoderma viride and inhibits growth of this fungus. Here we report on the effect of WGA, soybean agglutinin (SBA) and peanut agglutinin (PNA) on Penicillia and Aspergilli. Binding of the lectins to the fungi was examined with the aid of their fluorescein isothiocyanate (FITC) conjugated derivatives. FITC-WGA bound to young hyphal walls of all species, in particular to the hyphal tips and septa, in agreement with the chitinous composition of the cell walls of the two genera. Hyphae of all species examined were labelled, though in different patterns, by FITC-SBA and FITC-PNA, suggesting the presence of galactose residues on their surfaces. Young conidiophores, metulae (of the Penicillia), vesicles (of the Aspergilli), sterigmata and young spores, were also labelled. The three lectins inhibited incorporation of [3H]acetate, N-acetyl-D-[3h]glucosamine and D-[14C]galactose into young hyphae of Aspergillus ochraceus, indicating interference with fungal growth. Inhibition of spore germination by the three lectins was also observed. Preincubation of the lectins with their specific saccharide inhibitors prevented binding and the inhibitory effects. We conclude that lectins are useful tools for the study of fungal cell surfaces, and may also serve as an important aid in fungal classification. The present findings also support the suggestion that one role of lectins in plants is protection against fungal pathogens.

Aspergillus↗
PubMed1978

Colostomies--indications and contraindications: Lahey Clinic experience, 1963--1974.

Over a 12-year period, 276 temporary colostomies were performed on 271 patients. During this interval 118 colostomies were closed. The morbidity rate of colostomy construction was 21 per cent, and for closure it was 49.1 per cent. No definite factor could be indentified as contributing to this high rate of complications for colostomy construction. With respect to colostomy closure, predisposing factors that seemed to increase morbidity were shorter interval between creation and closure of the stoma and resection of colostomy (as opposed to closure without resection). Intra-abdominal drains were associated with a prohibitively high rate of wound infection, although subcutaneous drainage was not successful in reducing the incidence of infection significantly.

Adolescent↗
PubMed1978

Defect in biosynthesis of the linkage unit between peptidoglycan and teichoic acid in a bacteriophage-resistant mutant of Staphylococcus aureus.

The biosynthesis of the linkage region between peptidoglycan and the ribitol teichoic acid was investigated in the bacteriophage-resistant, teichoic acid-less mutant Staphylococcus aureus 52A5 (Chatterjee et al., J. Bacteriol. 100:846--853, 1969). Membrane preparations of this strain were found to be incapable of forming the first intermediate of the biosynthetic pathway, namely, the transfer of N-acetyl-D-glucosamine (GlcNAc) from UDP-GlcNAc to the acceptor molecule, which presumbably is undecaprenol phosphate (R. Bracha and L. Glaser, Biochem. Biophys. Res. Commun. 72:1091--1098, 1976). The addition of heat-inactivated membrane preparations of S. aureus 52A2 (which normally has ribitol teichoic acid) that had been preincubated with UDP-GlcNAc to membranes of strain 52A5 enabled the synthesis of teichoic acid. These data suggest that the mutational defect in the teichoic acid-less organism is in the synthesis of the first compound of the linkage unit, and this is apparently the reason for its absence in the cell walls.

Cell Wall↗
PubMed1978

Murein biosynthesis during a synchromous cell cycle of Escherichia coli B.

The last stages of murein biosynthesis were studied in relation to the division cycle of Escherichia coli in cells synchronized by amino acid starvation (Ron et al., J. Bacteriol. 123:374--376, 1975). Murein synthesis and the activities of the D-alanine carboxypeptidase and transpeptidase were found to vary significantly during the cell cycle. Maximal synthesis and transpeptidation were observed immediately after cell division, whereas maximal D-alanine carboxypeptidase activity was detected before cell division. These results are in agreement with our earlier findings that before cell division there is a stage of increased hydrolysis of the C-terminal D-alanine moiety of newly synthesized murein strands.

Carboxypeptidases↗