| the humoral immune response of mouse bone marrow lymphocytes in vitro. | mouse bone marrow (bm) small lymphocytes are shown to contain competent precursors for a primary haemolytic plaque forming cell (pfc) response to heterologous red blood cells and tnp in an in vitro culture system. their response is dependent on t co-operative factors, which can be provided by irradiated spleen cells activated by concanavalin a or the supernatant of an allogeneic culture, added at the beginning or after 24 h of culture. the frequency of pfc precursors for the response to srbc is ... | 1977 | 301118 |
| suppressor cells and loss of b-cell potential in mice infected with trypanosoma brucei. | the functional changes in splenic lymphoid populations from mice infected with t. brucei strain s42 were studied throughout the 3 weeks of infection. within a week of infection, proliferation of b and t cells profoundly increased as shown by 3h-labelled thymidine incorporation and fluorescent staining of surface ig; the spleen cells secreted high levels of both igm and igg immediately cells were put into culture; but with progressing infection this ig production declined. the early effect on t c ... | 1977 | 302169 |
| evidence that uv-inducible error-prone repair is absent in haemophilus influenzae rd, with a discussion of the relation to error-prone repair of alkylating-agent damage. | haemophilus influenzae rd and its derivatives are mutated either not at all or to only a very small extent by ultraviolet (uv) radiation, x-rays, methyl methanesulfonate, and nitrogen mustard, though they are readily mutated by such agents as n-methyl-n'-nitro-n-nitrosoguanidine, ethyl methanesulfonate, and nitrosocarbaryl. in these respects h. influenzae rd resembles the lexa mutants of escherichia coli that lack the sos or reclex uv-inducible error-prone repair system. this similarity is furth ... | 1977 | 302410 |
| attempts to induce mutations in haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine. | attempts were made to induce mutations in haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine. these attempts were unsuccessful. incorporation studies with brdurd showed, in agreement with earlier studies on escherichia coli, that brdurd was discriminated against when dthd was also present but was incorporated to essentially the same extent as dthd when only brdurd was present. in this latter case, strands fully substituted with brdurd was produced, but survival ... | 1977 | 302411 |
| l-asparagine requirements of human t-lymphocytes and b-lymphocytes in culture. | the characterization of two human t-lymphocyte lines revealed that they required exogenous l-asparagine for cell growth, whereas all four b-cell lines studied were l-asparagine independent. t-cells were 800-2,000 times more sensitive to escherichia coli l-asparaginase than were b-cells. the cytotoxic effects of a high concentration of l-asparaginase on b-cells were not related to the hydrolysis of l-asparagine but were due to heat-labile and heat-resistant substances in the enzyme. the findings ... | 1977 | 302863 |
| cellular events in tolerance. vi. neonatal vs adult b cell tolerance: differences in antigen-binding cell patterns and lipopolysaccharide stimulation. | the numbers and fate of antigen-binding cells (abc) in neonatal and adult mice rendered tolerant to fluorescein (fl)-labeled heterologous gamma-globulins were studied. similar numbers of fl-abc were observed 1 day after tolerogen in both adult and neonatal mouse spleens: by 7 days after tolerization, no fl-abc were observed in either case. reinjection with fl-tolerogen at 7 days led to the detection of normal numbers of abc in adult mice but significantly reduced numbers in neonates. this sugges ... | 1977 | 303254 |
| isolation and characterization of human fecal bacteria capable of 21-dehydroxylating corticoids. | it has been known for a decade that human intestinal flora include organisms capable of 21-dehydroxylating corticoids. yet the identity of the organisms synthesizing 21-dehydroxylase has remained unknown. using diluted human feces, we determined the prevalence of colonies of 21-dehydroxylating organisms on a variety of media. isolation from the medium of colonies with the highest prevalence yielded an obligate anaerobe capable of 21-dehydroxylating deoxycorticosterone and tetrahydrodeoxycorticos ... | 1977 | 303887 |
| ther persistent pha-responsive population in the mouse thymus. i. characterization of the population. | using an in vitro culture technique, mouse thymus graft cells were co-cultured with peripheral blood lymphocytes in the presence of phytohaemagglutinin (pha). the persistent pha-responsive thymus graft population (elliott, 1973) was shown to be able to response to other t-cell mitogens (con a, pokeweed mitogen, staphylococcal enterotoxin b), but not to e. coli lipopolysaccharide a known b-cell mitogen. the percentage of persistent pha-responsive cells did not alter during 5 days in culture and w ... | 1977 | 305408 |
| a dnase for apurinic/apyrimidinic sites associated with exonuclease iii of hemophilus influenzae. | an endonuclease purified from hemophilus influenzae made single strand breaks in dna containing apurinic or apyrimidinic sites but had no detectable endonuclease activity on untreated native dna. the new 5'-termini created at the cleavage sites were base-free deoxyribose 5-phosphate residues. the enzyme preparation also catalyzed the exonucleolytic release of 5'-mononucleotides from bihelical dna and the hydrolysis of dna 3'-terminal phosphomonoesters. the phosphatase-exonuclease activity was in ... | 1978 | 305919 |
| [immunological reactivity and the prognosis for allergic complications in the crew of the 2d saliut-4 expedition]. | immunological reactivity of p. i. klimuk and v. i. sevastyanov was studied before and after their 63-day flight aboard the orbital station salyut-4. the study used the methods to assay reactivity of t- and b-lymphocytes (pha-blast-transformation, nonspecific formation of rosettes with sheep red blood cells, immunofluorescence to identify cells carrying immunoglobulin receptors on their surface, serum level of immunoglobulins as a function of becells). sensitization of the human body to allergene ... | 1978 | 305975 |
| evidence against the reversion of mutation in the haemophilus influenzae phage hp1c1 by preinfection treatment of host cells or phage with mnng. | n-methyl-n'-nitrosoguanidine (mnng) causes reversion of a temperature-sensitive mutation in a bacteriophage of haemophilus influenzae if exposure to the mutagen takes place after infection but before lysis. however, neither pre-infection treatment of the phage dna, host cells, or both will cause reversion. the reasons for this are discussed in relation to the somewhat different results in the escherichia coli lambda phage system and in relation to error-prone repair and replication processes. | 1978 | 306062 |
| beta-lactamases and r-plasmids of haemophilus influenzae. | the emergence of resistance to ampicillin and other antibiotics in haemophilus influenzae has been a relatively recent event. in contrast, drug resistance has been rampant in the enterobacteriaceae for many years. ampicillin-resistance in h. influenzae is almost invariably attributable to possession of the tem (type iii a)beta-lactamase. as is common in other bacteria the gene specifying this enzyme is plasmid-borne in haemophilus. some ampicillin-resistant strains of h. influenzae can transfer ... | 1978 | 308259 |
| combined activitiy of clavulanic acid and ticarcillin against ticarcillin-resistant, gram-negative bacilli. | fifty-one clinical isolates of ticarcillin-resistant, gram-negative bacilli were tested for susceptibility to combinations of ticarcillin and clavulanic acid (brl 14151), a potent beta-lactamase inhibitor. minimal inhibitory concentrations (mics) were measured by a microdilution method, and minimal bactericidal concentrations for selected strains were measured by the broth dilution method. ticarcillin mics were >/=128 mug/ml for all and >/=512 mug/ml for 38 (75%) of the strains. thirty-nine stra ... | 1978 | 308792 |
| a chemical approach to the mechanism of b-lymphocyte activation. ii. the pure presentation of haptens does not inactivate b lymphocytes. | dinitrophenyl (dnp)-lysine-polymethylmethacrylate and dnp-cellulose conjugates do not irreversibly inactivate anti-dnp antigen-sensitive cells, regardless of the dose (up to 10 mg) or persistence of the stimulation (up to 2 weeks). since these conjugates constitute pure hapten presentations, it is concluded that the pure hapten presentation to b lymphocyte does not irreversibly inactivate them. when murine spleen cells are cultured with escherichia coli lipopolysaccharide (lps) and (non-immunoge ... | 1978 | 309627 |
| clavulanic acid, a novel inhibitor of beta-lactamases. | clavulanic acid, z-(2r,5r)-3-(beta-hydroxyethylidene)-7-oxo-4-oxa-1-azabicyclo-[3,2,0] heptane-2-carboxylic acid, has been shown to be an effective inhibitor of the beta-lactamases of the richmond types ii, iii, iv, and v. inhibition is a time-dependent reaction and is irreversible. clavulanic acid had poor antibacterial activity against staphylococcus aureus, enterobacteriaceae, and pseudomonas aeruginosa, with minimal inhibitory levels greater than 25 mug/ml. it did inhibit the majority of nei ... | 1978 | 310279 |
| sequence-specific dna uptake in haemophilus transformation. | haemophilus cells efficiently take up haemophilus dna from the medium during transformation but do not take up other dnas. to study the mechanism of this specificity we have cloned an 8.1-kilobase (kb) fragment of h. parainfluenzae dna in the escherichia coli--pbr322 host--vector system and reisolated the dna fragment for use as a defined probe. the 5'32p end-labeled 8.1-kb dna is efficiently absorbed by competent haemophilus cells whereas vector dna present in the mixture is not, implying that ... | 1979 | 311478 |
| comparative inhibition beta-lactamases by novel beta-lactam compounds. | the beta-lactamase-inhibiting activity of cp-45,899, 3,3-dimethyl-7-oxo-4-thia-1-azabicylo(3,2,0)heptane-2-carboxylic acid, 4,4-dioxide [2s-(2alpha,5alpha)], was investigated and compared with the beta-lactamase-inhibiting activity of clavulanic acid and dicloxacillin. cp-45,899 was an effective inhibitor of staphylococcus aureus beta-lactamase and of those beta-lactamases of gram-negative bacteria which are primarily active against penicillins or equally active against penicillins and cephalosp ... | 1979 | 311616 |
| plasmid-mediated ampicillin resistance in haemophilus ducreyi. | three of 19 strains of haemophilus ducreyi, isolated during a recent outbreak of chancroid, were found to produce beta-lactamase and to harbor a 6.0 x 10(6)-dalton plasmid. escherichia coli transformed with this plasmid acquired beta-lactamase-mediated resistance to ampicillin. the guanine-plus-cytosine content of the plasmid was found to be 41 mol%. restriction endonuclease digestion studies suggest that a relatively large portion of the tn1 translocon is carried by this plasmid. whereas this p ... | 1979 | 311618 |
| r plasmids in vibrionaceae - beta-lactamases in vibrio cholerae (nag-heiberg ii) and a. hydrophyla. | 290 natural isolates of aeromonas, plesiomonas and vibrio strains isolated from surface waters have been tested for antibiotic resistance, and 123 have been found resistant to various drugs, mostly beta-lactam antibiotics. 14 of them, with high-level of resistances, transfered antibiotic resistance using three recipient strains of enterobacteriaceae. one strain of vibrio nag (heiberg ii) transfered the resistance to ampicillin, carbenicillin and cephaloridin to both e. coli k12 3110 and s. typhi ... | 1978 | 311984 |
| humoral immunity before and after thymectomy in myasthenia gravis. | humoral immunity was studied in 10 patients with myasthenia gravis before thymectomy, in 15 different patients over 10 years after thymectomy, and in normal controls. antibody titers to acetylcholine receptor were significantly (p less than 0.01) lower in the post-thymectomy group. however, other antibody titers to common viruses, and to escherichia coli, and isohemagglutinins showed no significant change. levels of igm and ige (with atopic subjects excluded) decreased following thymectomy (p le ... | 1979 | 312471 |
| aging increases expression of lps-induced autoantibody-secreting b cells. | escherichia coli lipopolysaccharide (lps), a polyclonal b cell activator, has been employed to achieve in vitro stimulation of autoantibody-secreting b cells in young adult and aged mice of long-lived strains as assayed in a hemolytic plaque technique to syngeneic mouse erythrocytes. aged 21- to 24-month-old c57bl/6j and (c57bl/10sn x c3h/hedisn)f1 mice were found to express 3 to 4 times as many lps-induced plaque-forming cells (pfc) to autologous erythrocytes than did younger 6-month-old animal ... | 1979 | 312885 |
| predicted secondary structures of four penicillin beta-lactamases and a comparison with two lysozymes. | we have predicted the secondary structures of four beta-lactamases (bacillus cereus, bacillus licheniformis, staphylococcus aureus, and escherichia coli r-tem) by the statistical method of chou & fasman as well as by the information theory method of garnier et al. the secondary structures of all four beta-lactamases are of the alpha/beta type (levitt & chothia's nomenclature), with helices at n- and c-termini. there are about eight short regions each of alpha-helical (30--50%) and beta-strand (1 ... | 1979 | 313376 |
| in vitro activity and beta-lactamase stability of cefazaflur compared with those of beta-lactamase-stable cephalosporins. | the in vitro activity of cefazaflur, a parenteral cephalosporin, was determined against 590 clinical isolates. cefazaflur inhibited the majority of gram-positive cocci at concentrations below 1 mug/ml except for enterococci. the agent was as active as cefamandole or cefoxitin against most escherichia coli, klebsiella pneumoniae, and proteus mirabilis. although it inhibited a number of strains of enterobacter, indole-positive proteus, and serratia resistant to cephalothin, it was much less active ... | 1979 | 313753 |
| [ampicillin-resistant "haemophilus": their detection and occurrence in brussels area (author's transl)]. | three hundred and five strains of haemophilus (129 h. influenzae, 55 h. parainfluenzae, 97 h. parahaemolyticus, 5 h. haemolyticus, 10 h. paraphrophilus and 9 h. paraphrohaemolyticus) isolated from pathological material over the year 1976, were systematically tested for beta-lactamase production. only 2 strains of h. parainfluenzae produced this enzyme. both were able to transfer ampicillin resistance to escherichia coli k12. all strains but the two beta-lactamase producers were susceptible to pe ... | 1979 | 314252 |
| nitrous acid mutagenesis of duplex dna as a three-component system. | purified native hemophilus influenzae dna is relatively insusceptible to nitrous acid (na) mutagenesis in vitro, but is readily mutated following denaturation. na mutagenicity for duplex dna is significantly increased in the presence of various alcohols, glycols, phenols or primary amines. phenol-extracted dna contains dissociable contaminants of low molecular weight that enhance na mutagenesis. enhancement of na mutagenesis by phenol and by spermine is due to the formation of unstable molecular ... | 1979 | 314585 |
| comparative activity and beta-lactamase stability of cefoperazone, a piperazine cephalosporin. | the in vitro activity and beta-lactamase stability of 7-[d(-)-alpha-(4-ethyl-2,3-dioxopiperazino-carbonylamino) -p-hydroxyphenylacetamido]-3-[(1-methyl)-5-tetrazolylthiomethyl] -delta(3)-cephem-4-carboxylic acid (cefoperazone), a cephalosporin analog of piperacillin, were compared with the activities and stabilities of other cephalosporins and cephamycins. the compound was less active than cephalothin or cefamandole in inhibiting staphylococcus aureus; it was as active as cefamandole and cefoxit ... | 1979 | 314775 |
| immune activation by t-independent antigens: lack of effect of macrophage depletion on the immune response to tnp-lps, pvp and dextran. | carrageenan, a sulphated polysaccharide, and rabbit anti-mouse macrophage serum, were used to inhibit macrophage function in balb/c mice as well as to deplete macrophages from spleen cell cultures in an attempt to determine the requirement for macrophages in the immune response to several thymus-independent antigens. carrageenan inhibited macrophage function and was cytotoxic at low concentrations. the ability of t and b lymphocytes to undergo mitogen-induced proliferation in the presence of pha ... | 1979 | 315367 |
| antibacterial activity of ceftizoxime (fk 749), a new cephalosporin, against cephalosporin-resistant bacteria, and its stability to beta-lactamase. | antibacterial activity of fk 749 against ampicillin-resistant clinical isolates of escherichia coli was compared with those of other newly developed cephalosporins. fk 749 was the most active against strains possessing r-plasmids specifying ampicillin resistance and those whose resistance was chromosomally determined. the susceptibility of ampicillin-susceptible e. coli to fk 749 was not decreased by transduction of ampicillin resistance-specifying plasmids. however, most of the transconjugants ... | 1979 | 316684 |
| in vitro antibacterial activity of cefoperazone (t-1551), a new semisynthetic cephalosporin. | cefoperazone, a new semisynthetic cephalosporin, has a broad spectrum of antibacterial activity. it is as active as cefazolin and cefamandole against gram-positive bacteria and is more active than cefazolin and cefamandole against such gram-negative bacilli as escherichia coli, klebsiella pneumoniae, proteus species, pseudomonas aeruginosa, citrobacter freundii, enterobacter cloacae, and serratia marcescens. the superiority of cefoperazone over cefazolin and cefamandole with respect to activity ... | 1979 | 316988 |
| comparison of antibacterial activity of a new cephalosporin, ceftizoxime (fk 749) with other cephalosporin antibiotics. | fk 749 is a distinctive new parenteral cephalosporin antibiotic with a broad antibacterial spectrum which is more potently active against a wide variety of gram-negative bacilli, including the opportunistic pathogens such as citrobacter and enterobacter species and serratia marcescens, than sce 963, t 1551 and cefmetazole. the activity of fk 749 against escherichia coli, klebsiella pneumoniae, pyogenes was by far superior to that of the three other antibiotics. these test organisms were not resi ... | 1979 | 317284 |
| chemical composition and biological activities of a phenol-water extract from haemophilus influenzae type a. | ribonucleic acid was removed from a phenol-water extract of haemophilus influenzae type a by streptomycin sulfate. this preparation was called purified preparation or pp. it contained neutral sugars (glucose, galactose, mannose, pentose), glucosamine, amino acids, and fatty acids. heptose and 2-keto-3-deoxyoctonic acid were not present. the biological properties and immunogenicity were compared with the activities of lipopolysaccharide of escherichia coli or salmonella typhimurium. higher doses ... | 1979 | 317593 |
| synthesis of r-plasmid-coded beta-lactamase in minicells and in an in vitro system. | beta-lactamase encoded by a small, nontransferring r-plasmid, ntp1, conferring ampicillin resistance to its host bacteria, was purified. ntp1 plasmid-coded beta-lactamase was found to be periplasmically located in the host escherichia coli cell, to have a molecular weight of about 25,000, and to show a relatively low activity against oxacillin and methicillin compared with benzylpenicillin. these characteristics indicate that ntp1 plasmid-coded beta-lactamase is very similar or identical to the ... | 1977 | 318118 |
| cefoxitin therapy for surgical patients. | cefoxitin was administered to 25 patients on a general surgical service. in 16 of these patients, a bacteriologic diagnosis was made: four patients had peritonitis, one had ascending cholangitis, seven had cellulitis, and four had abscess. the dosage of cefoxitin varied from 4 to 8 g per day and was generally well tolerated, although there were three cases of phlebitis and one superinfection. there was no evidence of renal, liver, or bone marrow toxicity. all isolates of bacteroides (eight), esc ... | 1979 | 318221 |
| cefoxitin in treatment of obstetric and gynecologic infections. | cefoxitin was found to be an effective and safe agent for the treatment of infections of the female genital tract that were associated with a variety of aerobic and anaerobic bacteria, including streptococcus, escherichia coli, and bacteroides species. the overall clinical response was 91%. the major cause of failure was the presence of an abscess requiring surgical drainage. both the intravenous and the intramuscular routes of administration for cefoxitin were tolerated well or moderately well ... | 1979 | 318223 |
| isolation and characterization of escherichia coli k-12 f- mutants defective in conjugation with an i-type donor. | escherichia coli k-12 f- mutants defective in conjugation with an i-type donor (coni-) were isolated and characterized. these mutants are specific in that they are conjugation proficient with other types of donor strains. they have an altered susceptibility to phages and detergents. chemical analysis of the cell envelopes of mutant strains has shown that the lipopolysaccharide (lps) is altered and that one major outer-membrane protein is absent. conjugation experiments in which lps from wild-typ ... | 1977 | 318634 |
| effect of entry exclusion on mating aggregates and transconjugants. | mating aggregates during conjugation directed by an f-like r factor in escherichia coli were measured as the number of lac+-lac- sectored colonies present in a mating mixture. there is a high degree of correlation between the concentration of transconjugants produced in a mating mixture and the concentration of mating aggregates observed at several different concentrations of donor and recipient cells. the mating aggregates are sex pilus specific as demonstrated by the ability of donor-specific ... | 1977 | 318636 |
| phospholipid composition and phenotypic correction of an envc division mutant of escherichia coli. | the cytoplasmic and outer membranes of a nonconditional chain-forming mutant, escherichia coli pm61 envc, were separated by sucrose density gradient centrifugation. the phosphatidylglycerol/cardiolipin ratio in both membrane fractions was about one-third as high as in the parental strain p678. the increased level of cardiolipin in pm61 membranes is the result of an alteration of the polyglycerophosphatide cycle. it was found that the turnover rate of phosphatidylglycerol is more rapid in pm61 th ... | 1977 | 318637 |
| tetrahydrofolate-dependent biosynthesis of ribothymidine in transfer ribonucleic acids of gram-positive bacteria. | trimethoprim, an inhibitor that prevents tetrahydrofolate-dependent transmethylation reactions inbacteria, was used in a comparative study to discriminate between two possible biosynthetic pathways, either the s-adenosylmethionine or the tetrahydrofolate-dependent formation of ribothymidine (rt) in transfer ribonucleic acids (trna's) of several strains of gram-positive and gram-negative microorganisms. rt-deficient trna's accumulate in trimethoprim-treated gram-positive streptococcus faecium, st ... | 1977 | 318638 |
| transport and utilization of d-methionine and other methionine sources in escherichia coli. | the transport and utilization of d-methionine was investigated in several strains of escherichia coli k-12. wild-type cells exhibit a single transport system with a km of 1.16 mum. this activity exhibits a specificity similar to that of the uptake of l-methionine. the activity toward the d-isomer and the high-affinity uptake of l-methionine are lost in strains mutant in metd, along with the ability to utilize d-methionine as methionine source. both activities respond identically to gene dosage o ... | 1977 | 318639 |
| role of a sugar-lipid intermediate in colanic acid synthesis by escherichia coli. | membrane fractions from a lon strain of escherichia coli but not a wild-type strain catalyze the incorporation of fucose from guanosine 5'-diphosphate-fucose into a lipid and into polymeric material. both incorporation reactions specifically require only uridine 5'-diphosphate (udp)-glucose. the sugar lipid was shown to be an intermediate in the synthesis of the polymer which was related to colanic acid. the sugar lipid had the structure (fucose3, glucose2)-glucose p-p-lipid. its behavior on col ... | 1977 | 318640 |
| relation of cell growth and colicin tolerance to vitamin b12 uptake in escherichia coli. | the uptake of vitamin b12 was measured in cells of escherichia coli whose growth had been inhibited by any of a variety of treatments. in all cases, the secondary, energy-dependent phase of b12 uptake was depressed in proportion to the decrease in growth rate, but uptake was constant in cells growing logarithmically at different rates. the depression of b12 uptake activity was independent of the site of cell metabolism affected by the inhibitor or by its effect on cell viability, and was both mo ... | 1977 | 318641 |
| thymidine-requiring mutants of salmonella typhimurium that are defective in deoxyuridine 5'-phosphate synthesis. | in a salmonella typhimurium strain made diploid for the thy region by introduction of the escherichia coli episome, f'15, mutants resistant to trimethoprim in the presence of thymidine were selected. one was shown to be defective in deoxyuridine 5'-phosphate (dump) synthesis; it requires deoxyuridine or thymidine for growth and is sensitive to trimethoprim in the presence of deoxyuridine. genetic studies showed that the mutant is mutated in two genes, dcd and dum, located at 70 and 18 min, respe ... | 1977 | 318643 |
| chemical measurement of steady-state levels of ten aminoacyl-transfer ribonucleic acid synthetases in escherichia coli. | polypeptide chains of 10 aminoacyl-transfer ribonucleic acid synthetases (those for arginine, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, phenylalanine, threonine, and valine) have been identified in lysates of escherichia coli resolved by the o'farrell two-dimensional gel system. by labeling cells uniformly with [14c]glucose and by measuring the total amounts of these polypeptides by their radioactivity, estimations of the steady-state, molecular amounts of these enzymes wer ... | 1977 | 318645 |
| initiation of protein synthesis without formylation in a mutant of escherichia coli that grows in the absence of tetrahydrofolate. | starting from a p-aminobenzoate-requiring strain of escherichia coli (e. coli k-12 ab3292), we have isolated mutants that can grow in the absence of p-aminobenzoate (and thus tetrahydrofolate). the following lines of evidence suggest that at least one of these mutants is capable of initiating protein synthesis without formylation of methionyl-transfer ribonucleic acid (methionyl-trna(fmet)). (i) trna isolated (and charged in vivo with [(35)s]methionine) from this mutant grown in a p-aminobenzoat ... | 1977 | 318648 |
| fine-structure mapping of the rts, rplk, rpll, and rpob genes of escherichia coli. | the specialized transducing phage lambdaci857s7drifd18 was used as a donor in a transductional mapping of four genes in the rif region of the escherichia coli genome. the gene order was rts-2.9-rpll-0.8-rpob, where the numbers indicate intermarker distances in kilobases. the possible orientation of these genes with respect to each other and to neighboring genes is discussed. | 1977 | 318652 |
| number of mutations required to evolve a new lactase function in escherichia coli. | the frequency of mutation of the ebgao allele to ebga+ was compared with the frequency of mutation of stra+ to stra-. the observation that both spontaneous and ethyl methane sulfonate-induced mutations to ebga+ occurred more frequently than mutations to stra- suggests that ebga+ mutants arise as the result of single-point mutations. | 1977 | 318653 |
| threonyl-transfer ribonucleic acid synthetase and the regulation of the threonine operon in escherichia coli. | two threonine-requiring mutants with derepressed expression of the threonine operon were isolated from an escherichia coli k-12 strain containing two copies of the thr operon. one of them carries a leaky mutation in ilva (the structural gene for threonine deaminase), which creates an isoleucine limitation and therefore derepression of the thr operon. in the second mutant, the enzymes of the thr operon were not repressed by threonine plus isoleucine; the threonyl-transfer ribonucleic acid(trna) s ... | 1977 | 318654 |
| nuclear-spin-labeled nucleic acids. 1 19f nuclear magnetic resonance of escherchia coli 5-fluorouracil-5s-rna. | | 1977 | 318664 |
| alteration of effectiveness of antibiotics by anaerobiosis. | in vitro antibiotic susceptibility tests of facultative organisms are routinely performed under aerobic conditions, despite the fact that many infections caused by these organisms occur in anaerobic areas, i.e., intra-abdominal absess. experiments were performed aerobically and anaerobically to determine the susceptibility of e. coli, p. mirabilis, and k. pneumoniae to gentamicin, tobramycin, cephalothin, cefazolin, and cefamandole. antibiotic sensitivities were determined by disc and agar dilut ... | 1977 | 318675 |
| outbreak of meningitis in a newborn intensive care unit caused by a single escherichia coli k1 serotype. | three cases of meningitis that occurred during a nine-day period in a newborn intensive care unit were caused by a single e. coli serotype 07:k1:h-. a single organism outbreak was suspected when the three spinal fluid isolates all possessed the same two unusual bacteriologic and biochemical characteristics: nonmotile and ornithine negative. culture surveillance identified eight infants colonized with the same strain of e. coli; three of these infants are described. clusters of cases of e. coli m ... | 1977 | 318683 |
| hereditary deficiency of the third component of complement in a child with fever, skin rash, and arthralgias: response to transfusion of whole blood. | a previously well 34-month-old male presenting with fever, skin rash, and arthralgias was found to lack c3 by immunochemical (undetectable) and hemolytic (1% normal) assays. no infectious agent could be demonstrated. protein levels of clq. c4, c5, properdin, and c3b-ina and hemolytic activities of complement components c1 to c9 except c3 were normal or elevated; total hemolytic complement activity was 13% of normal and was reconstituted by purified c3. properdin factor b was 702 (normal 175 to 2 ... | 1977 | 318684 |
| nucleotide sequences from the rabbit beta globin gene inserted into escherichia coli plasmids. | a 169-nucleotide region from the rabbit beta globin gene has been sequenced by analysis of complementary dna's cloned in bacterial plasmids. comparison of these sequences with those established for this gene by other techniques provides evidence of a high degree of fidelity and allows the unambiguous establishment that these plasmids do not contain harmful sequences. | 1977 | 318762 |
| quality control of small-volume sterile products. | a method for bacterial surveillance of small-volume sterile products in hospitals was developed and tested. the criteria for the method of quality control were to: (1) assure detection of contamination associated with touch, which could occur during the filling process; (2) be economically feasible; (3) be simple and easy to implement; and (4) be versatile in adapting to small-volume sterile packages with and without needles. ten percent of each lot of prepackaged unit dose syringes is tested by ... | 1977 | 318798 |
| antimicrobial spectrum, pharmacology and therapeutic use of antibiotics. part 2: penicillins. | the mechanism of action, resistance, antibacterial spectrum, clinical pharmacology, adverse effects, and therapeutic and prophylactic use of penicillins are reviewed. the choice of a penicillin is discussed. the only indication for the penicillinase-resistant penicillins is the suspected or demonstrated presence of staphylococcus aureus. there are no important differences in therapeutic effect among oxacillin, cloxacillin, dicloxacillin or flucloxacillin by the oral route, or among oxacillin, di ... | 1977 | 318800 |
| histamine and sympathetic blockade in septic shock. | the relative roles of endogenously released histamine and the sympathetic nervous system in septic shock were indirectly studied by blocking each one separately. antihistamines in doses of 3-10 mg/kg prevented severe blood pressure drops and improved urinary output in groups treated before and after shock. release of histamine seems to be important at least in the pathogenesis of early septic shock, although analysis of blood pressure pattern and survival implicates additional factors in late sh ... | 1977 | 318812 |
| transcription of yeast dna by homologous rna polymerases i and ii: selective transcription of ribosomal genes by rna polymerase i. | purified yeast dna was transcribed by homologous rna polymerases i and ii and escherichia coli rna polymerase. transcripts synthesized in vitro were analyzed by molecular hybridization with complementary dna (cdna) synthesized from yeast poly(a)-containing mrna with viral reverse transcriptase and ribosomal dna labeled in vitro by nick translation with e. coli dna polymerase i. rna synthesized by polymerase i and ii in the presence of mn2+ contained sequences complementary to cdna and rdna at a ... | 1977 | 318852 |
| influence of cationic triphenylmethane dyes upon dna polymerization and product hydrolysis by escherichia coli polymerase i. | the cationic triphenylmethane dyes crystal violet, methyl green, and malachite green inhibited dna synthesis catalyzed by escherichia coli b polymerase i (polymerase i). lower concentrations of the dyes inhibited dna replication as a direct function of the proportion of at to gc in the dna of clostridium perfringens, escherichia coli, and micrococcus lysodeikticus. when the intercalant proflavin was employed, the gc-rich micrococcal dna was most severely inhibited. in addition, both the tripheny ... | 1977 | 318853 |
| evidence for involvement of the electron transport system at a late step of anaerobic microbial heme synthesis. | the penultimate step in heme biosynthesis, the oxidation of protoporphyrinogen to protoporphyrin, can be anaerobically coupled to the reduction of fumarate in extracts of anaerobically-grown escherichia coli. this coupling is approximately 90% inhibied by 2-heptyl-4-hydroxy quinoline-n-oxide (hqno), a known inhibitor of the electron transport chain. this observation suggests that the mechanism of the anaerobic oxidation of protoporphyrinogen in e. coli involves a coupling into the anaerobic elec ... | 1977 | 318855 |
| the effects of n-ethylmaleimide on active amino acid transport in escherichia coli. | n-ethylmaleimide (malnet) binds covalently and without specificity to accessible sulfhydryl residues in proteins. in some cases specificity has been imposed on this reaction by manipulating reaction conditions, yielding information concerning both enzyme mechanism and the identity of specific proteins (for example c.f. fox and e.p. kennedy (1965) proc. natl. acad. sci. u.s. 54, 891-899) and r.e. mccarty and j. fagan (1973) biochemistry 12, 1503-1507). we have examined the effects of malnet on th ... | 1977 | 318857 |
| induction of lesions in deoxyribonucleic acid by low molecular weight substances from normal and colicin e2-treated cells of escherichia coli. | a fraction containing a variety of low molecular weight substances was extracted into 80% aqueous acetone from both a colicin e2-treated cell culture of escherichia coli and an untreated one. the extract was divided into five fractions by sephadex g15 chromatography. one of them, fraction b, was separated into three subfractions by sephadex g10 chromatography. two subfractions, fraction bi and fraction bii, were further fractionated by several chromatographic systems. dna was incubated with an a ... | 1977 | 318858 |
| synthesis of guanosine 5'-diphosphate, 3'-diphosphate in spot mutants of escherichia coli. | the synthesis of ppgpp in spot- mutants of escherichia coli has been invesitgated. in these mutants the first-order rate constant for ppgpp breakdown is low, and pppgpp is barely detectable. it is shown that the rate of pppgpp, and hence ppgpp, synthesis is strongly reduced compared with that observed in spot+ strains. the low rate of magic spot synthesis satisfactorily explains the low levels of pppgpp in spot- mutants. the pentaphosphate very probably is the precursor of ppgpp as it is in wild ... | 1977 | 318860 |
| triton x-100 activates nucleoside triphosphate-dependent, recbc-dependent dna synthesis in toluene-treated escherichia coli. | escherichia coli cells whose chromosome replication has been terminated in vivo, either by growth into stationary phase or by incubation of a mutant carrying a temperature-sensitive initiation mutation under restrictive conditions, are inactive in in vitro dna synthesis as measured in toluene-treated cells. addition of the non-ionic detergent triton x-100 to such inactive systems results in a marked stimulation of atp-dependent in vitro dna synthesis. this triton-stimulated dna synthesis appears ... | 1977 | 318867 |
| the 30 s subunit of the escherichia coli ribosome. topographical model of its component proteins. | this topographical model of the proteins of the 30 s subunit of the escherichia coli ribosome was built to be consistent with the 37 published spectroscopic and chemical experiments that indicate proximity and with the two neutron diffraction experiments that indicate s3 and s7 as well as s2 and s5 to be separated by 110 a. the model is quite consistent with the protein arrangement suggested by assembly pathways, the various rna binding sites, and the streptomycin-associated proteins, this consi ... | 1977 | 318869 |
| spectral studies of the interactions of escherichia coli alkaline phosphatase with 4-(4-aminophenylazo)-phenylarsonic acid. | escherichia coli alkaline phosphatase (ec 3.1.3.1) is reversibly inhibited by a variety of phenylarsonic acids, including some n-haloacetylated derivatives. the inhibition is of the competitive type, and ki values are reported. the action on the enzyme of one of the arsonate inhibitors, the azo dye, 4-(4-aminophenylazo)-phenylarsonic acid was studied in detail, using spectrophotometric and kinetic methods. the azo dye binds more strongly to e. coli alkaline phosphatase than do the other arsonate ... | 1977 | 318870 |
| effect of fosfomycin on the fecal microflora of man. | use of broad-spectrum antibiotics is known to cause changes in the intestinal microflora of man. the present study was initiated to determine the effect of oral fosfomycin calcium on several groups of microorganisms indigenous to the gut. data from this double-blind study indicate that 2 g of fosfomycin given daily in four divided doses for 28 days increased the incidence of soft stools. no significant changes in numbers of staphylococci or candida were observed during treatment. although there ... | 1977 | 318971 |
| genetic localization of the resistance to fosfomycin. | the possible existence of a transferable resistance to fosfomycin was studied in 50 strains of enterobacteria that were isolated in our hospital and which showed a resistance to fosfomycin of more than 256 mug/ml. e. coli k12 e711 was used as a receptor strain in the conjugation -- the times of conjugation were 20 min and 18 h. we found a transferable resistance in 28% of the strains. in all but one of the cases, only the resistance to fosfomycin was transferred. the recombinant which received t ... | 1977 | 318972 |
| fosfomycin and plasmidic resistance. | 60 fosfomycin-resistant strains of gram-negative bacilli are submitted to conjugation experiments using as recipient cell e. coli k12 which is nalidixic acid resistant. after mating, the number of fosfomycin-resistant e. coli k2 colonies growing on selection plates containing nalidixic acid and fosfomycin never surpassed the normal rate of mutation for fosfomycin-resistance of the recipient strain. in 65% of the experiments, plasmidic resistance to other antimicrobials was transferred to e. coli ... | 1977 | 318973 |
| enteropathogenic e. coli gastroenterocolitis in neonates treated with fosfomycin. | the effect of calcium salt of fosfomycin in the treatment of 43 neonates suffering from acute gastroenterocolitis produced by enteropathogenic e. coli is evaluated. the minimal inhibitory concentration of these e. coli was, generally, lower than 128 mug/ml. dosages of 150-200 mg/kg body weight/day were administered orally every 8 h. this treatment lasted for 4 days only. clinical evolution was favorable in 38 (88%) babies and bacteriological evolution in 30 (70%). in eight cases a different flor ... | 1977 | 318975 |
| neurosurgical infection treated with fosfomycin and 6-methylprednisolone. | a left parietal parasagittal meningioma was removed in a 67-year-old female patient. in the postoperative period she had a neurosurgical cerebral suppurating infection: subdural, epidural and epicranial, connected to the exterior by several fistulas. in the operative revision and after a culture, the germ causing the infection, e. coli, was isolated. treatment was begun with 16 g of intravenous fosfomycin and 120 mg daily of 6-methylprednisolone intramuscularly, and this treatment cured the pati ... | 1977 | 318976 |
| combined action of fosfomycin with beta-lactam and aminoglycoside antibiotics. | the combined action of fosfomycin with penicillin g, ampicillin and streptomycin was investigated. a total of 11 s. aureus and 10 e. coli were included in these studies. it has been shown that a combination of fosfomycin with penicillin g and streptomycin resulted in a synergistic effect. when s. aureus strains were tested, the combination of fosfomycin with penicillin g was more frequently effective than the combination of fosfomycin with streptomycin. the combinations of fosfomycin with ampici ... | 1977 | 318979 |
| interactions of yeast trnaphe with ribosomes from yeast and escherichia coli. a fluorescence spectroscopic study. | the interaction of ethidium-labeled trnaphe from yeast with ribosomes from yeast and escherichia coli was studied by stead-state measurements of fluorescence intensity and polarization. the ethidium label was covalently inserted into either the anticodon or the dihydrouridine loop of the trna. the codon-independent formation of a trna-ribosome complex led to only a moderate increase of the observed fluorescence polarization indicating a considerable internal mobility of the labeled parts of the ... | 1977 | 318996 |
| the stereochemical basis of template function. | the behavior of nucelotides with thioketo-substituted pyrimidine bases (4-thiouracil, 2-thiouracil and 2-thiocytosine) or amino-analogue purine bases (2-aminopurine and 2,6-diaminopurine) in transcription and translation was investigated. the experimental results obtained led to the following conclusions. 1. the stereochemical basis of substrate selection in transcription is the geometry of watson-crick base pairs a-u (or a-t) and g-c between substrate and template bases. 2. the topology of the ... | 1977 | 319000 |
| the effect of initiation factor if-1 on the dissociation of 70-s ribosomes of escherichia coli. | by means of exchange studies, in which 3h-labelled 50-s subunits and unlabelled 70-s ribosomes from escherichia coli mre 600 were used, it has been demonstrated that the 30-s subunit is the only target for if-3 in the dissociation of 70-s ribosomes. the interference of if-3 with the dynamic equilibrium of 70-s in equilibrium 50-s + 30-s occurs by binding of the factor to the 30-s subunit. the 30-s-if-3 complex in impaired in the association reaction, which implies that if-3 is acting as an anti- ... | 1977 | 319002 |
| isolation of a spermatozoal immobilization factor from escherichia coli filtrates. | a low-molecular weight spermatozoal immobilization factor (sif) has been isolated from escherichia coli cultures. this factor is stable to heating, freezing, and lyophilization, and immobilizes but does not kill spermatozoa. the concentration of spermatozoa influenced the effectiveness of the sif in immobilizing spermatozoa, indicating that bacterial infections could have a greater influence on the oligospermic ejaculate than on a normal specimen. sif is a stable factor and binds to spermatozoa ... | 1977 | 319021 |
| induction of escherichia coli and vibrio cholerae enterotoxins by an inhibitor of protein synthesis. | enterotoxigenic escherichia coli or vibrio cholerae 569b (inaba) grown in the presence of the antibiotic lincomycin, an inhibitor of protein synthesis, produced elevated levels of heat-labile enterotoxin or choleragen, respectively, as assayed by both vascular permeability factor and capacity to elicit fluid accumulation in rabbit ileal loops. this induction of enterotoxin did not reflect either a coupling of lincomycin resistance with increased enterotoxigenicity or an effect of lincomycin on c ... | 1977 | 319055 |
| mechanism of steroid action in ocular inflammation: inhibition of prostaglandin production. | prostaglandin e (pge) concentration the aqueous humor of an intact rabbit eye was less than 0.1 ng. per milliliter and increased to 19 +/- 3 ng. per milliliter 60 minutes following paracentesis. the rise in pge level was associated with clinical signs of ocular inflammation. pretreatment with triamcinolone reduced both the accumulation of pge in the aqueous humor and the inflammatory response following paracentesis. intravitreal injection of e. coli endotoxin into rabbit eyes increases pge leve ... | 1977 | 319076 |
| significant bacteriuria among the mentally retarded. identification and antibiotic sensitivity of isolates. | a study was carried out to determine the prevalence of significant bacteriuria in a mentally retarded population. with 100,000 or more bacteria per ml. of urine used as a criterion for significant bacteriuria, 24 of 665 persons studied were considered to have significant bacteriuria for an overall prevalence rate of 3.6%. seventeen of the 24 positive urine cultures were either from clean catch or catheter specimens. all patients undergoing catheterization were found to have significant bacteriur ... | 1977 | 319080 |
| effect of oral inoculation of escherichia coli on colostral antibody production in cattle. | oral inoculation of approximately 1.2 x 10(9) viable escherichia coli to pregnant cows resulted in increased blood serum and colostral whey titers to the "o" antigen. the antibody titers were more pronounced in colostral whey and were correlated with the inoculum strain of escherichia coli. there was no correlation between antibody titers of the colostrum ingested and the resulting serum antibody titers of the calves. the incidence of diarrhea in calves did not correlate with the antibody titer ... | 1977 | 319088 |
| on the role of atp in phosphodiester bond hydrolysis catalyzed by the recbc deoxyribonuclease of escherichia coli. | the deoxyribonuclease specified by the recb and recc genes of escherichia coli (recbc dnase; exonuclease v) has been purified to near homogeneity by a new procedure. although hydrolysis of even a single nucleotide from a duplex dna molecule by the pure enzyme is absolutely dependent upon atp, the extent of phosphodiester hydrolysis is strongly inhibited by atp concentrations of 0.2 mm or greater, and the initial rate is unaffected. under these conditions, the extent of dna hydrolysis is proporti ... | 1977 | 319095 |
| antagonistic action between spermidine and putrescine on association and dissociation of purified, run-off ribosomes from escherichia coli. | the effects of polyamines on the equilibrium between prokaryotic ribosomal subunits and 70 s ribosomes have been studied as a function of concentration of mg2+ from 2.5 to 7.5 mm. run-off ribosomes were obtained from escherichia coli and were washed with buffered 1 m nh4c1. spermidine at 1 mm favors association of subunits at all concentrations of mg2+. putrescine, at concentrations above 8 mm, favors net dissociation at concentrations of mg2+ below 4.5 mm. streptomycin behaves like spermidine, ... | 1977 | 319096 |
| ultrastructure of a periodic protein layer in the outer membrane of escherichia coli. | matrix protein (36,500 daltons), one of the major polypeptides of the escherichia coli cell envelope, is arranged in a periodic monolayer which covers the outer surface of the peptidoglycan. although its association with the peptidoglycan layer is probably tight, the periodic structure of the peptidoglycan. although its association with the peptidoglycan later is probably tight, the periodic structure is maintained in the absence of peptidoglycan, and is therefore based on strong protein-protein ... | 1977 | 319099 |
| inhibition of immune hemolysis: serological assay for the heat-labile enterotoxin of excherichia coli. | sheep erythrocytes sensitized by incubation with the heat-labile enterotoxin (lt) of escherichia coli are hemolyzed in the presence of anti-lt antiserum and complement. the microtiter (cooke laboratory products) technique was used to titrate anti-lt antibody in serum by this immune hemolysis reaction. immune hemolysis was inhibited by preexposure of the anti-lt antiserum to soluble lt before addition of the lt-sensitized sheep cells. e. coli mini-extract preparations were obtained by the polymyx ... | 1977 | 319105 |
| development of a lysis-filtration blood culture technique. | a lysed-blood culture system that quickly lyses patients' blood near neutrality and is relatively noninjurious to more delicate pathogens such as haemophilus influenzae and bacteroides fragilis is reported. the lysing solution includes culture medium, 0.004 m sodium carbonate and bicarbonate, 0.04% triton x-100,and 0.6% rhozyme (a mixture of proteases). most of the pathogens tested multiplied in the lysing solution. the lysed blood normally is immediately filtered. the membrane is transferred to ... | 1977 | 319108 |
| harmful effects of near-ultraviolet radiation used for polymerization of a sealant and a composite resin. | an electronic device used to polymerize a sealant and a composite resin has been found to emit 365-nanometer radiation at levels sufficient to kill the bacterium escherichia coli rapidly (greater than 14,000 ergs per square millimeter per second). because of the absence of shielding on the probe, significant amounts of energy (up to 45% of that at the probe tip) were measured at the sides of the probe. these findings--supported by the well-documented findings of biological damage caused by near- ... | 1977 | 319134 |
| bacteriostasis of escherichia coli by milk. i. colonization of breast-fed infants by milk resistant organisms. | human milk has a bacteriostatic effect on escherichia coli in vitro. the milks of 40 mothers were tested for this effect against e. coli isolated from their stools, from those of their own babies, and from those of babies not breast-fed. the milks had a direct bacteriostatic effect, not dependent on complement, on some but not all the strains of e. coli. breast-fed babies receiving supplementary bottle feeds were colonized with milk-resistant strains, whereas bottle-fed babies and, surprisingly, ... | 1977 | 319169 |
| escherichia coli serotypes in the faeces of healthy adults over a period of several months. | the faeces of nine subjects eating mainly at home were collected at regular intervals over periods ranging from 2--5 months. although a large number of serotypes of e. coli were isolated, the variety per subject was lower than is usually found. in most subjects only a limited number of serotypes persisted over most of the periods of study while many serotypes were only isolated on single occasions. | 1977 | 319170 |
| the nature of the proteins in 'chloramphenicol particles' from escherichia coli a19 (hfr rel met rns). | the unusual particles which accumulate in cell-free extracts from escherichia coli a19 during chloramphenicol inhibition ('chloramphenicol particles') have been isolated by large-scale rate-zonal density gradient ultracentrifugation. the proteins and rna species composing these particles have been examined. the rrna species present are precursor and mature forms of 16s and 23s rrna which accumulate during inhibition. the proteins prepared directly from the particles give strong multiple immunopr ... | 1977 | 319193 |
| excystment of axenically prepared cysts of hartmanella culbertsoni. | axenically prepared cysts of hartmannella culbertsoni readily excysted in the presence of heat stable factors prepared from escherichia coli, klebsiella aerogenes, staphylococcus aureus, sarcina lutea, bacillus subtilis, bacillus megaterium and several fungi. peptone, proteose peptone, tryptone or amino acids also promoted excystment. crowding of the cysts and dilution of bacterial extracts adversely affected the excystment. continual presence of the factors in the medium was essential for excys ... | 1977 | 319194 |
| microbial metabolism of amino alcohols. control of formation and stability of partially purified ethanolamine ammonia-lyase in escherichia coli. | induction of ethanolamine ammonia-lyase formation in escherichia coli required both the ethanolamine and vitamin b12, and was gratuitous during growth on glycerol. ethanolamine analogues inhibited enzyme activity and inhibited growth with ethanolamine as the the nitrogen source, but did not act as inducers. enzyme formation was more rapid when ethanolamine was added to cultures containing vitamin b12 rather than the reverse. enzyme formation was subject to catabolic repression, glucose and aceta ... | 1977 | 319195 |
| the nature of the proteins present in the 'relaxed particles' from methionine-starved escherichia coli a19 (hfr rel met rns). | the 'relaxed particles' formed during methionine starvation of escherichia coli a19 (hfr rel met rns) have been isolated by large-scale rate-zonal density gradient ultracentrifugation. the proteins and rrna species associated with these particles have been examined. the rrna species present are precursor and mature forms of 16s and 23s rrna. the bulk of the rrna which accumulates during starvation is found within the particles. the proteins prepared directly from the particles give strong multip ... | 1977 | 319197 |
| fluctuations in buoyant density during the cell cycle of escherichia coli k12: significance for the preparation of synchronous cultures by age selection. | the buoyant densities of escherichia coli k12 were investigated by isopycnic centrifugation in gradients of colloidal silica (ludox) and polyvinylpyrrolidone. bacteria from an exponential culture in a defined medium supplemented with hydrolysed casein banded at densities between 1-060 and 1-115 g ml-1; the mean density was 1-081 g ml-1. at the higher densities, two populations of cells were present: smaller cells were approximately twice as numerous as, and half the modal volume of, the populati ... | 1977 | 319198 |
| aerobic and anaerobic bacterial respiration monitored by electrodes. | a technique is described by which both oxygen and nitrate (or nitrate or chlorate) levels were continuously monitored during bacterial respiration. paracoccus (micrococcus) denitrificans and escherichia coli oxidizing succinate rapidly ceased to reduce nitrate when oxygen was available, and equally rapidly commenced nitrate reduction when all the oxygen had been consumed. by contrast, membrane vesicles isolated from p. denitrificans reduced oxygen and nitrate simultaneously. the respiratory nitr ... | 1977 | 319200 |
| introduction of bacteriophage mu into pseudomonas solanacearum and rhizobium meliloti using the r factor rp4. | phage mu-1 and a thermoinducible derivative, mu-1 cts 62 were inserted into the broad host range r factor rp4. these hybrid plasmids were transferred by conjugation to a phytopathogenic bacterium pseudomonas solanacearum gmi 1000 and a legume-root nodule bacterium rhizobium meliloti 2011. the mu genome is transcribed and tranlated in these new hosts: p. solanacearum (rp4:mu cts) cultures have a spontaneous production of about 5 x 10(5) plaque-forming units ml-1 which is similar to the frequency ... | 1977 | 319201 |
| antibacterial structure-activity relationships obtained with resistant microorganisms i: inhibition of r-factor resistant escherichia coli by tetracyclines. | aparent partition coefficients and inhibitory activities against sensitive and resistant escherichia coli were determined for 14 tetracyclines. the difference in the kinetics of inhibition of the two organisms is discussed in terms of their permeabilities. the partition coefficients were determined in an octanol-buffer system. values for eight compounds were in general agreement with the literature; values for the remaining six compounds had not been reported previously. growth of the organisms ... | 1977 | 319218 |
| semisynthetic cephalosporins. synthesis and structure-activity relationships of analogues with 7-acyl groups derived from 2-(cyanomethylthio)acetic acid or 2-[(2,2,2-trifluoroethyl)thio]acetic acid and their sulfoxides and sulfones. | the synthesis and in vitro and in vivo activities of a series of cephalosporins having side chains derived from 2-[(2,2,2-trifluoroethyl)thio]acetic acid or 2-(cyanomethylthio)acetic acid and with acetoxymethyl or 3-heterocyclic thiomethyl substituents at the 3 position are described. in both series, increasing the oxidation state of the side-chain sulfur atom from sulfide to sulfoxide/sulfone decreased the in vitro gram-positive activity, but the effect on gram-negative activity was variable an ... | 1977 | 319233 |
| quantitative structure-activity relationships of antimalarial and dihydrofolate reductase inhibition by quinazolines and 5-substituted benzyl-2,4-diaminopyrimidines. | a quantitative structure-activity relationship (qsar) for the inhibition of dihydrofolate reductase from s. faecium by quinazolines has been formulated. this is compared with a qsar for inhibition of e. coli dihydrofolate reductase by 2,4-diamino-5-benzylpyrimidines. the qsar for inhibition of bacterial enzyme is compared with qsar for mammalian enzyme inhibition. a qsar has been formulated for the antimalarial action of quinazolines against p. berghei in mice. the antimalarial qsar is consisten ... | 1977 | 319234 |
| p-aminobenzoic acid derivatives as inhibitors of the cell-free h2-pteroate synthesizing system of escherichia coli. | a heterogeneous series of compounds, derived from p-aminobenzoic acid (paba), has been investigated for their paba-antagonistic potency in a cell-free h2-pteroate synthesizing system of e. coli. a prerequisite of compounds, other than sulfones or sulfonamides, to compete with paba for the enzyme h2-pteroate synthetase appeared to be the presence of a p-aminobenzoyl moiety. substitution of the carboxyl group of paba by an ester, an amide, or a ketone function, however, strongly reduces the abilit ... | 1977 | 319235 |
| conformation and molecular organization in fibers of the capsular polysaccharide from escherichia coli m41 mutant. | | 1977 | 319241 |
| streptomycin-resistant escherichia coli mutant temperature sensitive for the production of qbeta-infective particles. | a streptomycin-resistant escherichia coli mutant has been isolated that is temperature sensitive for qbeta phage, but not for the group i rna phages f2, ms2, and r17. the growth of qbeta in the mutant at the nonpermissive temperature (42 degrees c) results in the release of a near-normal burst of noninfectious particles that cosediment with qbeta in a sucrose gradient. it is assumed that the mutant is defective at elevated temperatures in the suppression of nonsense codons, thereby producing qbe ... | 1977 | 319250 |
| effect of spermidine on the rna-a protein complex isolated from the rna bacteriophage ms2. | the polyamine spermidine has recently been reported to be a substantial component of the rna phage particle. its effect on the isolated rna-a protein complex of the phage ms2 is investigated here. this complex infects intact escherichia coli cells via f-pili, as does the whole phage. it is shown that the infectivity of the complex on intact e. coli cells was enhanced by incubation with spermidine. optimal stimulation (20-fold) of the complex infectivity was achieved by incubation with 3 x 10(-4) ... | 1977 | 319252 |