| mecillinam (fl 1060), a 6beta-amidinopenicillanic acid derivative: in vitro evaluation. | mecillinam (formerly called fl 1060), a novel 6beta-amidinopenicillanic acid derivative, showed markedly higher activity than ampicillin against clinical isolates of enterobacteriaceae. the mode of action of mecillinam is different from that of ampicillin and consequently no intrinsic cross-resistance between the two antibiotics was observed. mecillinam is inactivated by beta-lactamases but is generally more stable than ampicillin; thus an apparent cross-resistance exists for strong beta-lactama ... | 1975 | 241287 |
| localization of the structural change induced in trna fmet (escherichia coli) by acidic ph. | we have compared the molecular mechanism of thermal unfolding for native trna fmet (escherichia coli) and the denatured species produced by annealing at ph 4.3. relaxation kinetic measurements reveal that the transitions assigned to melting of tphic, anticodon, and acceptor stem helices at neutral ph remain essentially unaltered at ph 4.3, but the transition corresponding to coupled melting of tertiary structure and dihydrouridine helix is greatly affected. the tm of this region is more than 20 ... | 1975 | 241372 |
| purification and properties of a ribosomal protein methylase from eschericha coli q13. | ribosomal protein methylase has been purified from escherichia coli strain q13 using methyl-deficient 50s subunits as substrates. the purified enzyme (or enzyme complex) which is devoid of rrna methylating activity is quite stable and has a ph optimum around 8.0. the km for s-adenosyl-l-methionine is 3.2 mum. the molecular weight of the enzyme is 3.1 x 10(4); minor methylating activity was also detected for protein peaks with molecular weights of 1.7 x 10(4) and 5.6 x 10(4). protein l11 is the m ... | 1975 | 241395 |
| the action of beta-galactosidase (escherichia coli) on allolactose. | the parameters involved in the action of beta-galactosidase (ec 3.2.1.23) (escherichia coli) on allolactose, the natural inducer of lac operon in e. coli, were studied. at low allolactose concentrations only galactose and glucose were formed, while at high allolactose concentrations transgalactolytic oligosaccharides were also produced. detectable amounts of lactose were not formed. the v and km values (49.6 u/mg and 0.00120 m, respectively) indicated that allolactose is as good if not a better ... | 1975 | 241475 |
| atp synthesis driven by protonmotive force imposed across escherichia coli cell membranes. | | 1975 | 241667 |
| glutamate dehydrogenase from escherichia coli: purification and properties. | glutamate dehydrogenase (l-glutamate:nadp+ oxidoreductase [deaminating], ec 1.4.1.4) has been purified from escherichia coli b/r. the purity of the enzyme preparation has been established by polyacrylamide gel electrophoresis, ultracentrifugation, and gel filtration. a molecular weight of 300,000 +/- 20,000 has been calculated for the enzyme from sedimentation equilibrium measurements. polyacrylamide gel electrophoresis in sodium dodecyl sulfate and sedimentation equilibrium measurements in guan ... | 1975 | 241744 |
| isolation and characterization of the newly evolved ebg beta-galactosidase of escherichia coli k-12. | the ebg beta-galactosidase of escherichia coli k-12 strain lc110 has been purified and characterized. strain lc110 is a lac+ revertant of a mutant with a deletion of the lacz beta-galactosidase gene. its new ebg beta-galactosidase activity was shown to be due to a discrete protein, immunologically unrelated to lacz beta-galactosidase. its kinetics of action conformed to those of a simple conventional enzyme. with o-nitrophenyl-beta-d-galactoside as substrate, the vmax was 11,200 nmol/min per mg ... | 1975 | 241745 |
| purification and properties of bacillus subtilis aspartate transcarbamylase. | aspartate transcarbamylase from bacillus subtilis has been purified to apparent homogeneity. a subunit molecular weight of 33,500 +/- 1,000 was obtained from electrophoresis in polyarcylamide gels containing sodium dodecyl sulfate and from sedimentation equilibrium analysis of the protein dissolved in 6 m guanidine hydrochloride. the molecular weight of the native enzyme was determined to be 102,000 +/- 2,000 by sedimentation velocity and sedimentation equilibrium analysis. aspartate transcarbam ... | 1975 | 241753 |
| escherichia coli enterotoxin. purification and partial characterization. | enterotoxin, a diarrheagenic protein elaborated by pathogenic escherichia coli strains has been isolated from the supernatant of fermenter cultures of e. coli strain p263, a porcine enteropathogen. purification steps involving bio-gel agarose a-5m, sephadex g-75 chromatography, and preparative isotachophoresis were used in the isolation. the resulting product appears to be pure according to immunoelectrophoretic, disc electrophoretic, ultracentrifugal, and immunologic criteria. the entertoxin ha ... | 1975 | 241754 |
| antibacterial activity of cationic proteins from human granulocytes. | human granulocytes contain several cationic proteins with a molecular weight of approximately 25,000, almost identical amino acid composition, and complete immunologic identity. these proteins possess a chymotrypsin-like protease activity at a neutral ph. the antibacterial activity of the cationic proteins has been studied. bactericidal activities are found against both gram-positive (streptococcus faecalis and staphylococcus aureus) and gram-negative (escherichia coli and pseudomonas aeruginosa ... | 1975 | 241758 |
| microbial kinetics of drug action against gram-positive and gram-negative organisms. ii: effect of clindamycin on staphylococcus aureus and escherichia coli. | clindamycin-affected staphylococcus aureus cultures show biphasic steady-state generation curves. an initial (phase i) generation of the clindamycin-affected staph. aureus is followed by an ultimate (phase ii) generation at the same dose level. the phase i apparent generation rate constant is greater than the phase ii apparent generation rate constant and suggests the development of resistant staph. aureus mutants to clindamycin action after a finite period of drug-bacteria contact at any subcom ... | 1975 | 241826 |
| gel entrapped l-asparaginase: kinetic behavior and antitumor activity. | l-asparaginase from escherichia coli was immobilized by entrapment in a gel based on poly(2-hydroxyethyl methacrylate) with an activity as high as 730 i.u./g of dry gel. the apparent michaelis constant for these gels was similar to that of the free enzyme. at 37 degrees c the immobilized enzyme had a half-life of more than 40 days, in vitro. the gel was freeze-dried, crushed and sieved to pass a 38 mum screen, giving a median particle size of 12 mum. c3h mice were injected intraperitoneally with ... | 1975 | 241845 |
| crystals of glutamine synthetase from escherichia coli. | | 1975 | 241853 |
| singlet energy transfer studies of the arrangement of proteins in the 30 s escherichia coli ribosome. | | 1975 | 241859 |
| the isolation and characterization of glutamine-requiring strains of escherichia coli k12. | mutants of escherichia coli k12 requiring glutamine as a nitrogen source were isolated, and characterized as lacking glutamine synthetase activity. temperature sensitive revertants of one of the mutants had a heat labile glutamine synthetase, while temperature insensitive revertants had a glutamine synthetase which was thermostable in vitro, indicating that the mutation was in the structural gene for the enzyme. all of the mutations mapped in the same region of the chromosome suggesting that the ... | 1975 | 241928 |
| omega-aminoalkyl agaroses in the resolution of enzymes involved in regulation of glutamine metabolism. | systematic examination of a homologous series of omega-aminoalkyl agaroses showed that the pentyl derivative (seph-c5-nh2) was best suited for the retention and subsequent separation of several proteins involved in the regulation of glutamine metabolism in escherichia coli, including: glutamine synthetase [ec 6.3.1.2; l-glutamate:ammonia ligase (adp-forming)], atp:glutamine synthetase adenylyltransferase (ec 2.7.7.42), the pii regulatory protein which regulates the adenylylation and deadenylylat ... | 1975 | 242003 |
| 31p magnetic resonance of trna. | we have observed well-resolved 31p resonances at 65 kg (109 mhz) in solutions of escherichia coli trnaglu and yeast trnaphe. one resolved resonance, identified as the terminal phosphate, titrates with a pk = 6.35. upon melting the yeast trnaphe in 0.1 m nacl, without mg++, the resolved peaks broaden and disappear in the vicinity of 35 degrees while the central cluster narrows drastically, shifts slightly, and loses its structure. addition of mg++ shifts one resolved peak and changes the shape of ... | 1975 | 242005 |
| gene transfer to human cells: transducing phage lambda plac gene expression in gmi-gangliosidosis fibroblasts. | genetic information from the bacterium escherichia coli was transferred to human cells by means of the specialized transducing phage lambda plac carrying the bacterial z gene for the enzyme beta-galactosidase (geta-d-galactoside galactohydrolase, ec 3.2.1.23). as recipient cells, cultured skin fibroblasts from a patient with generalized gangliosidosis (gmi-gangliosidosis type i) characterized by a severe deficiency of beta-galactosidase activity were used. the deficient human cells were incubate ... | 1975 | 242006 |
| hematological findings in acute infections and septicemias. | this paper is a report on twelve cases of septicemia, the diagnosis made possible by medical technologists observing the degenerative morphological findings in the peripheral blood smears. this led to the finding of microorganisms, prior to the bacteriological confirmation, in an active emergency department. it also includes four case reports in which the organism was identified: a meningococcus, a pneumonococcus, an escherichia coli, and a clostridium perfringens (welchii). | 1975 | 242218 |
| adsorption and selection of rhizobia with ion-exchange papers. | ion exchange papers were used to study the adsorption of 32p-labelled rhizobia on defined surfaces. two strains of rhizobium japonicum and one each of r. leguminosarum and r. lupini were compared with escherichia coli and bacillus subtilis. the ratio of adsorption to strong and to weak acid papers/strong and weak basic papers was consistantly higher for all rhizobial strains compared to the other bacteria. the process of desorption by increasing the ion-concentration causes about 35% desorption ... | 1975 | 242293 |
| the human leukocyte photoreactivating enzyme. | a photoreactivating enzyme from human leukocytes has been isolated and characterized. the enzyme requires dna irradiated with ultraviolet light (220-300 nm) as substrate, and visible light (300-600 nm) for catalysis. in the reaction, the enzyme converts cyclobutyl pyrimidine dimers in the dna to monomer pyrimidines. the enzyme has an apparent monomer molecular weight of 40,000 and tends to form aggregates. the ph optimum of 7.2 and absence of a requirement for metal ions are similar to the requi ... | 1975 | 242311 |
| endonuclease iii: an endonuclease from escherichia coli that introduces single polynucleotide chain scissions in ultraviolet-irradiated dna. | an endonuclease that makes single polynucleotide chain scissions in uv-irradiated dna has been purified from escherichia coli. the activity has the following properties: (1) unirradiated dna is attacked very little if at all; (2) single-stranded dna is not attacked, whether irradiated or not; (3) there is no requirement for divalent cations, and the activity is not affected by addition of edta; (4) the ph optimum is approximately 7; (5) the activity is inhibited by 1 m nacl, single-stranded dna, ... | 1975 | 242312 |
| [diarrhea outbreak and bacterial resistance to ampicillin in newborns]. | twenty-eight healthy neonates from the san juan de dios hospital were studied to determine the pattern of antibiotic resistance of indigenous intestinal bacteria. sixty-eight per cent of infants had enterobacteriaceae resistant to several wide-spectrum antibiotics, including ampicillin; 28 per cent of the cultures had plasmid-mediated ampicillin resistance. in the course of the study, an outbreak of 10 acute cases of diarrhea occurred, not associated to any of the commonly known agents, includin ... | 1977 | 242927 |
| further evidence that elongation factor 1 remains bound to ribosomes during peptide chain elongation. | this paper describes three types of experiments which indicate that the binding sites for elongation factor 1 (ef-1) and elongation factor 2 (ef-2) on ascites cell ribosomes are not identical and perhaps not even overlapping. the experimental evidence presented includes direct competitive binding of labeled elongation factors to ribosomes as well as the influence of pokeweed antiviral protein and escherichia coli anti l7/l12 proteins on the binding and function of the two factors. it is further ... | 1977 | 242941 |
| introduction. membrane transport of peptides. | carrier-mediated membrane transport of small peptides is now realized to be a process of wide biological distribution, occurring not only in the small intestine and elsewhere in the animal body but also in bacteria, yeast, the mould neurospora crassa, and probably in higher plants during the germination of seeds. the important features of peptide transport are outlined, and possible relationships between peptide transport and hydrolysis are discussed. peptide transport is a stereochemically spec ... | 1977 | 244390 |
| [in vitro antibacterial activity of tobramycin used in combination with cephalothin or carbenicillin (author's transl)]. | combinations of tobramycin (tob) with cephalothin (cet) or carbenicillin (cbpc) were evaluated by in vitro test against 161 clinical isolates of klebsiella pneumoniae, escherichia coli, indole-positive proteus, enterobacter and serratia marcescens which were not inhibited by 6.25 microgram/ml of cet. the combinations were considered to show synergy when there was a 4-fold or greater reduction in mic values (fic index less than or equal to 0.5) of both antibiotics when combined. synergy of tob wi ... | 1978 | 246946 |
| [talampicillin hydrochloride: comparison with amoxicillin and ampicillin in the antibacterial activity and pharmacokinetics (author's transl)]. | the antibacterial activities, absorption and excretion of talampicillin hydrochloride were compared with those of amoxicillin and ampicillin. talampicillin hydrochloride showed a broad-spectrum antibacterial activity against gram-positive and gram-negative bacteria as seen in amoxicillin and ampicillin. the antibacterial activities of talampicillin hydrochloride, amoxicillin and ampicillin were quite similar. in experimental murine infection with staphylococcus aureus, protective effect of talam ... | 1978 | 246947 |
| cefuroxime, a beta-lactamase-resistant cephalosporin with a broad spectrum of gram-positive and -negative activity. | the in vitro activity of cefuroxime, a cephalosporin antibiotic, was investigated against 604 isolates and compared with the activity of other beta-lactam compounds. cefuroxime had activity comparable to that of other cephalosporins, including cefamandole and cefoxitin, against streptococcal and staphylococcal species; most streptococci were inhibited by 0.1 mug or less per ml, and staphylococci were inhibited by 1.6 mug or less per ml. enterococci were relatively resistant. cefuroxime inhibited ... | 1978 | 248268 |
| antibacterial activity of apalcillin (pc-904) against gram-negative bacilli, especially ampicillin-, carbenicillin-, and gentamicin-resistant clinical isolates. | apalcillin (pc-904) is active against carbenicillin- and ampicillin-resistant strains of gram-negative bacilli. among pseudomonas aeruginosa strains highly resistant to carbenicillin (>/=3,200 mug/ml), half of them were susceptible to pc-904 at a concentration of 50 to 1,600 mug/ml. the minimal inhibitory concentration of pc-904 against p. aeruginosa strains resistant to carbenicillin (400 to 1,600 mug/ml) ranged from 3.1 to 25 mug/ml. ampicillin- and carbenicillin-resistant enterobacteriaceae s ... | 1978 | 248269 |
| chemical modification as a probe of conformational changes in transfer ribonucleic acid on aminoacylation. | treatment of escherichia coli ca265 phenylalanyl-trna with 3m-nahso3, ph6.0, at 25 degrees c resulted in modification of four bases and in the deacylation of the charged trnaphe. the similarity of the rates of base modification and of the deacylation of the phenylalanyl-trna permitted the isolation of partially modified phenylalanyl-trnaphe and partially modified deacylated trnaphe. the sites and extents of base modification in these fractions were determined and found to be the same as those in ... | 1978 | 248282 |
| hr 756, a highly active cephalosporin: comparison with cefazolin and carbenicillin. | hr 756, a new parenteral cephalosporin, was compared with cefazolin and carbenicillin for activity against a total of 264 strains of pseudomonas aeruginosa, escherichia coli, klebsiella spp., proteus mirabilis, proteus spp. (indole positive), enterobacter spp., salmonella typhi, serratia marcescens, providencia stuartii, and staphylococcus aureus. in every comparison, except that with the last organism, hr 756 was clearly more active than cefazolin and carbenicillin. all three compounds had simi ... | 1978 | 253572 |
| continuous infusion tobramycin combined with carbenicillin for infections in cancer patients. | the cure rate of infections in cancer patients is adversely affected by neutropenia (less than 1,000/mm3). in particular, patients with severe neutropenia (less than 100/mm3) have shown a poor response to antibiotics. to overcome the adverse effects of neutropenia, tobramycin was given by continuous infusion and combined with intermittent carbenicillin. tobramycin was given to a total daily dose of 300 mg/m2 and carbenicillin was given at a dose of 5 gm every four hours. there were 125 infectiou ... | 1979 | 256433 |
| comparative activities of ampicillin, epicillin and amoxycillin in vitro and in vivo. | the antibacterial activities of three aminopenicillins ampicillin, epicillin and amoxycillin were compared in vitro and in vivo. the minimum inhibitory concentrations (mic) of the three penicillins were very similar and the compounds were active against non-beta-lactamase-producing strains of escherichia coli, salmonella and shigella species, proteus mirabilis, haemophilus influenzae and neisseria gonorrhoeae. streptococci including streptococcus faecalis, and non-beta-lactamase-producing staphy ... | 1979 | 256524 |
| specific induction of pulmonary indoleamine 2,3-dioxygenase by bacterial lipopolysaccharide. | indoleamine 2,3-dioxygenase (molecular weight about 42,000) has been purified from rabbit intestines and contains one mole of protohaem ix as the sole prosthetic group. it catalyses the oxidative cleavage of the pyrrole ring of various indoleamines with a much broader specificity of substrate than tryptophan 2,3-dioxygenase. the enzyme has an absolute requirement for superoxide anion for catalytic activity. the enzyme was induced specifically in the lungs of mice for 24 h after administration of ... | 1978 | 258162 |
| characterization of r-plasmids coding for ampicillin resistance from salmonella species. | a sudden increase in the incidence of ampicillin resistance was observed among salmonella species isolated within new zealand in 1973--4. this increase was due mainly to the apperance and proliferation of salmonella newington and salmonella anatum serotypes resistant to ampicillin. the plasmid complements of 14 ampicillin-resistant s. newington and s. anatum isolates obtained from widely separated geographical areas within new zealand between 1973 and 1974 were characterized by agarose gel elect ... | 1979 | 258658 |
| zymosan-induced resistance to endotoxin and hemorrhagic shock. | improved surgical techniques and judicial use of available antibiotics have reduced the number of postoperative complications over the past decade. however, septic and hemorrhagic shock occur all too frequently, and each carries with it an appreciable morbidity and mortality. endotoxins and hemorrhage are both known to suppress the phagocytic activity of the reticuloendothelial system (res). on the other hand, zymosan, a yeast (saccharomyces cerevisiae) cell wall preparation administered intrave ... | 1978 | 262077 |
| effect of reticuloendothelial blockade on the development of hypotension after trauma, sepsis, and intravascular coagulation. | numerous studies have demonstrated that reticuloendothelial system (res) depression induced by colloid blockade increases susceptibility to circulatory shock following trauma and sepsis. recent data have suggested that this may relate to the failure of the res to clear potentially embolic material derived from activation of the hemostatic system. the present study thus compared the hypotensive response precipitated by trauma or sepsis with that resulting from induction of intravascular coagulati ... | 1979 | 262805 |
| [evolution of the repartition of enteropathogenic enterobacteria serotypes isolated in algeria from 1974 to 1977]. | the authors survey the enteropathogenic enterobacteria studied from 1974 to 1977 and draw the following conclusions : s. typhi is still the predominant serotype. among salmonella, other than s. typhi and s. paratyphi, s. wien remains the most frequently reported serotype while progressively decreasing from 1974 to 1976 and is supplanted by s. infantis in 1977. among the 847 strains of shigella examined, a high frequency of shigella flexneri is noted with shigella sonnei following by a wide margi ... | 1978 | 262974 |
| transcriptional features of fractionated human breast tumor chromatin. | by means of controlled mechanical shearing it was possible to fractionate human breast tumor chromatin in "active" and "inactive" species, according to their in vitro template activity, using escherichia coli rna polymerase. the "active" molecules can be resolved in three well defined regions in an exponential sucrose gradient, showing approximately 300 times the efficiency for synthesizing ribonucleic acid, relative to the chromatin which migrated fastest. this technique could provide the initi ... | 1979 | 263221 |
| treatment of osteomyelitis and septic arthritis with cefazolin. | sixteen cases of severe osteomyelitis and septic arthritis caused by staphylococci, streptococci, gonococci, and a variety of gram-negative bacilli were treated with 4 to 8 g of parenteral cefazolin per day; nine received subsequent therapy with oral cephalexin or ampicillin. of 16 infections, 15 were apparently cured. cefazolin concentrations in those patients were: serum (peak), 25 to 216 micrograms/ml; synovial fluid, 24 to 46 micrograms/ml; and bone, 3.2 to 10.6 micrograms/g. bacterial patho ... | 1978 | 263883 |
| initiation of genetic exchanges in lambda phage--prophage crosses. | when escherichia coli k-12 (lambda) lysogens were infected with lambda phages, genetic exchanges between phage and prophage occurred at low frequencies (less than 0.1% between the markers p3 and p80), but at frequencies above 1% if the infecting phages were first treated with the photosensitizing agent 4,5',8-trimethylpsoralen and 360 nm light. exchanges were induced by psoralen damage at about the same frequency in wild-type lysogens and in those carrying recb(-), recc(-), recf(-), or lexa(-), ... | 1977 | 264683 |
| selective and accurate transcription of the xenopus laevis 5s rna genes in isolated chromatin by purified rna polymerase iii. | chromatin isolated from immature oocytes was found to contain an endogenous rna polymerase activity (rna nucleotidyltransferase; nucleoside triphosphate:rna nucleotidyltransferase, ec 2.7.7.6) that synthesizes predominately 5s rna. however, the levels of total rna synthesis and 5s rna synthesis in chromatin were each stimulated 10- to 50-fold by an exogenous rna polymerase iii purified from x. laevis oocytes. the 5s genes in chromatin were transcribed by the exogenous enzyme in a highly selectiv ... | 1977 | 264693 |
| a nucleotide sequence from a ribonuclease iii processing site in bacteriophage t7 rna. | transcription of that portion of the bacteriophage t7 genome encoding early functions yields rna molecules about 7500 nucleotides long representing this entire early region. these long transcripts can be cleaved in vitro by highly purified escherichia coli ribonuclease iii (endoribonuclease iii; ec 3.1.4.24), yielding five messenger rnas identical to those produced in vivo. during this reaction, a small rna fragment called f5 rna is released, which is specified by the region of the t7 genome bet ... | 1977 | 265576 |
| specific gonadotropin binding to pseudomonas maltophilia. | binding of 125i-labeled human chorionic gonadotropin to pseudomonas maltophilia is dependent on time, temperature, and ph and the binding to this procaryotic species is hormone-specific and saturable. the equilibrium dissociation constant is 2.3 x 10(-9) m. there are no cooperative interactions between binding sites (hill coefficient, 1.05). the number of sites is estimaated as 240 fmol/100 mug of protein. nacl and kcl, at concentrations from 1 to 10 mm, have no effect on binding. divalent catio ... | 1977 | 265583 |
| role of dna gyrase in phix replicative-form replication in vitro. | preparations containing dna gyrase activity gellert, m., mizuchi, k., o'dea, m.h. & nash, h.a. (1976) proc. natl. acad. sci. usa 73, 3872-3876] have been extensively purified from escherichia coli. such fractions, in the presence of atp and mg2+, catalyze supertwisting of relaxed circular double-stranded dna replicative forms of a number of dnas that results in the formation of superhelical replicative forms. relaxed phix174 replicative form (phix rfiv) is not attacked by the a protein endonucle ... | 1977 | 266716 |
| susceptibility of various microorganisms to chlorhexidine. | the susceptibility to chlorhexidine of bacteria in aerobic, facultatively anaerobic and anaerobic isolates from clinical specimens of wounds, urine, saliva, and dental plaque was studied. agar diffusion tests using 50 microng chlorhexidine discs and agar dilution tests were performed and the mic values correlated with inhibition zone diameters. anaerobic plaque strains were isolated and tested by the agar dilution method in an anaerobic glove box. regression lines obtained for five agar media de ... | 1977 | 266752 |
| studies on nucleic acid reassociation kinetics: retarded rate of hybridization of rna with excess dna. | the rate of reaction of excess double-stranded bacteriophage phix174 and plasmid rsf2124 dna drivers with enzymatically synthesized asymmetric rna tracers was measured. other reactions were carried out with excess escherichia coli dna and e. coli rna labeled in vivo. rna and dna fragment lengths were held approximately equal. for each case it was shown that in dna excess the rate constant for rna-dna hybridization is 3- to 4.5-fold lower than that of the renaturation rate constant for the driver ... | 1977 | 267925 |
| a dna fragment containing the origin of replication of the escherichia coli chromosome. | a 38 kilobase pair region of the escherichia coli k12 chromosome containing the replication origin has been physically mapped with restriction endonucleases ecori and hindiii. replication starts within or very near a 1.3 kilobase pair hindiii fragment in the middle of this region and proceeds outward in both directions with apparently equal speed. this pattern was observed in both dnaa and dnac temperature-sensitive (ts) initiation mutants at the start of the synchronous round of replication whi ... | 1977 | 268621 |
| discontinuous replication of replicative form dna from bacteriophage phix174. | bacteriophage phix174 dna has been labeled with short pulses of [3h]thymidine during synthesis of replicative form molecules in infected escherichia coli hf4704 cells. the replicating phix174 dna was isolated and analyzed by sedimentation in an alkaline sucrose gradient. during a brief pulse (5 sec at 30 degrees), the radioactivity incorporated into the complementary strand was found in chains much shorter than one genome length. of the radioactivity incorporated into the viral strand, two-third ... | 1977 | 268627 |
| dna or rna priming of bacteriophage g4 dna synthesis by escherichia coli dnag protein. | escherichia coli dnag protein is involved in the initiation of dna synthesis dependent on g4 or st-1 single-stranded phage dnas [bouche, j.-p., zechel, k & kornberg, a. (1975) j. biol. chem. 250, 5995-6001]. the reaction occurs by the following mechanism: dnag protein binds to specific sites on the dna in a reaction requiring e. coli dna binding protein. an oligonucleotide is synthesized in a reaction involving dnag protein, dna binding protein, and dna. with g4 dna this reaction requires adp, d ... | 1977 | 268632 |
| identification and cloning of the chloroplast gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase from chlamydomonas reinhardi. | mrna coding for the large subunit (ls) of ribulose-1,5-bisphosphate carboxylase [3-phospho-d-glycerate carboxy-lyase (dimerizing), ec 4.1.1.39] from chlamydomonas reinhardi has been isolated from small polyribosomes immunoadsorbed to column-bound anti-ls antibody. 32p-labeled ls mrna was used as a hybridization probe to detect ls genes. the probe hybridized to c. reinhardi chloroplast dna and at hybridization saturation revealed that there are approximately 75 ls genes per chloroplast. when chlo ... | 1977 | 269382 |
| phix174 cistron a protein is a multifunctional enzyme in dna replication. | the cistron a protein induced by phage varphix174 nicks (produces a single-strand break in) the viral strand of the superhelical varphix duplex dna, thereby forming a complex with the dna. the protein, seen bound to the dna in the electron microscope, was located in the restriction endonuclease fragment between nucleotides 4290 and 4330 on the varphix map [sanger, f., air, g. m., barrel, b. g., brown, n. l., coulson, a. r., fiddes, j. c., hutchison, c. a., iii, slocomb, p. m. y. & smith, m. (197 ... | 1977 | 269383 |
| role of ribothymidine in mammalian trnaphe. | we have previously reported that mammalian trnasphe from variation tissues contain different amounts of ribothymidine and that a uridine methylase from escherichia coli can quantitatively convert these trnas to species that contain their full complement ofribothymidine at position 23 from the 3' terminus. the role of ribothymidine in mammalian trnas has now been investigated by studying the ability of several highly purified mammalian trnasphe, differing only in their ribothymidine content, to s ... | 1977 | 269424 |
| antibacterial activity of extracts from some african chewing sticks. | the antibacterial activity of aqueous, isobutanol, and benzene extracts of five popular african chewing sticks was studied by the agar ditch plate method. the isobutanol extract produced the greatest antimicrobial activity, and the benzene extract the least. streptococci were the most sensitive to the extracts, while escherichia coli was the most resistant. it would appear that the active principles of the various chewing-stick extracts are not the same and that the extract from a given chewing ... | 1977 | 270068 |
| synthesis of phix174 viral dna in vitro depends on phix replicative form dna. | a cell-free system that catalyzes phix174 replicative form i (supercoiled circular duplex, rfi)-dependent phix174 dna synthesis has been isolated from escherichia coli infected with phix174 phage. the products formed with such preparations are viral strands as judged by hybridization to poly(u,g) followed by equilibrium centrifugation in cscl. this phix174 dna-synthesizing involves formation of dna-protein complexes that sediment in neutral sucrose with s values of 50, 60-70, and higher. the 50s ... | 1977 | 270663 |
| computer analysis of nucleic acid regulatory sequences. | we describe a computer program designed to facilitate the analysis of nucleic acid sequences. the program can search several nucleic acid sequences for oligonucleotides common to all of them. it can examine a dna or rna sequence for two kinds of homologous regions--repetitions and dyad symmetries. the homologies need not be perfect: mismatches and "looping out" of nucleotides are allowed. the program also finds (a+t)- and (g+c)-rich regions, locates restriction enzyme recognition sites, determin ... | 1977 | 270683 |
| sequence of an oligonucleotide derived from the 3' end of each of the four brome mosaic viral rnas. | a 3'-terminal oligonucleotide fragment, 161 bases long, can be obtained from each of the four brome mosaic virus rnas by means of nuclease digestion. like the four intact brome mosaic virus rnas, each fragment accepts tyrosine in a reaction catalyzed by wheat germ aminoacyl-trna synthetase. the complete nucleotide sequence of the rna 4 fragment has been determined by use of standard radiochemical methods. comparative data for the fragments from rnas 1, 2, and 3 show that they have nearly the sam ... | 1977 | 270723 |
| rna polymerase binding sites in lambdaplac5 dna. | the in vitro binding of the escherichia coli rna polymerase (nucleosidetriphosphate:rna nucleotidyltransferase; ec 2.7.7.6) to fragments of lambdaplac5 dna generated by restriction endonucleases hindii and hindiii has been studied by a filter binding technique. the results are consistent with rna polymerase binding at p(r)', the int promoter (p(i)), several sites in the b2 region, the mis promoter, the oop promoter (or p(o)), and p(rm). binding was also observed on some fragments that are not kn ... | 1977 | 270725 |
| phage t4-modified rna polymerase transcribes t4 late genes in vitro. | initiation of t4 late rna synthesis has been achieved in an in vitro system prepared from escherichia coli cells infected with wild-type or maturation-defective mutant t4 phage. the system uses a cellophane membrane as a mechanical support for concentrated cell lysates and for added streptolydigin-resistant rna polymerases. transcriptional activity and selectivity of added rna polymerases are tested while endogenous rna polymerase activity is inhibited by streptolydigin. t4-modified rna polymera ... | 1977 | 271954 |
| structure of nascent replicative form dna of coliphage m13. | nascent replicative form type ii (rfii) dna of coliphage m13 synthesized in an escherichia coli mutant deficient in the 5' leads to 3' exonuclease associated uith dna polymerase i contains ribonucleotides that are retained in the covalently closed rfi dna sealed in vitro by the joint action of t5 phage dna polymerase and t4 phage dna ligase. these rfi molecules are labile to alkali and rnase h, unlike the rfi produced either in vivo or from rfii with e. coli dna polymerase i and e. coli dna liga ... | 1978 | 272630 |
| l-asparaginase in treatment of acute leukemia in children. | l-asparaginase from escherichia coli--crasnitin was used in 14 children with acute leukemia unresponsive to conventional treatment: 11 acute lymphoblastic leukemias, 1 acute myeloblastic leukemia, 2 other forms of leukemia. the remission induction was obtained in 70% of applications. median of remission duration was 90 days. serious side effects were observed. the validity of l-asparaginase in therapy of advanced childhood all is stressed. | 1978 | 273152 |
| discrete length classes of dna depend on mode of dehydration. | the length of double-stranded coliphage lambda dna, as determined by electron microscopy using the benzyldimethylalkyl ammonium chloride technique, depends on the mode of dehydration. the freeze-dried dna form is the longest (16.5 micron), whereas dehydration in methanol (15.9 micron) or in ethanol (three forms: 15.2 micron, 13.9 micron, and 12.4 micron) results in progressively shorter molecules. these measured lengths of the freeze-dried, methanol-dehydrated, and shortest ethanol-dehydrated fo ... | 1978 | 273234 |
| construction and characterization of an escherichia coli plasmid bearing a functional gene g of bacteriophage phix174. | in order to study the mutagenic effects of site-specific, covalent modifications of biologically active dna, we need host cells that are permissive for any type of mutation that might be produced in vivo from the modified dna. specifically, we require a general, in vivo complementation system for the bacteriophage phix174 gene g, an essential gene that we have chosen for our initial studies of chemical mutagenesis. toward this end, we have constructed a plasmid (pphixg) that carries a functional ... | 1978 | 273240 |
| strand-specific break near the origin of bacteriophage p2 dna replication. | membrane-associated p2 dna isolated early after infection under conditions that block replication (amb in phage and rep in escherichia coli c) was analyzed by electron microscopy. most dna was in the form of relaxed circles (40%) and circles with short single-stranded tails (60%). when this dna was hybridized with separate strands of linear p2 hy dis dna (which provides suitable reference points along the heteroduplex molecules), an interruption was located near the previously mapped origin of p ... | 1978 | 273899 |
| synthesis of phage m13 coat protein and its assembly into membranes in vitro. | the coat protein (gene 8 product) of coliphage m1o is an integral protein of the host cell membrane at all stages of virus infection. this protein, when made in a cell-free reaction, has been shown by others to have an additional nh2-terminal peptide region and is referred to as "procoat." it is initially not membrane-bound but, upon exposure to escherichia coli membrane vesicles or to liposomes prepared from e. coli lipids, it assembles into the bilayer in an integral fashion. much of this prot ... | 1978 | 273906 |
| dna polymerase activities in differentiating mouse neuroblastoma n-18 cells. | the activities of two dna polymerases (dna nucleotidyltransferases) were characterized in mouse neuroblastoma clone n-18 on the basis of their apparent molecular weights (determined by sucrose density gradient centrifugation: polymerase-alpha, 7.5-8 s; polymerase-beta, 3-4 s) and relative inhibition by sulfhydryl-blocking agents. n-ethylmaleimide (10 mm) and iodoacetamide (1.5 mm) inhibited dna polymerase-alpha activity completely, whereas only 35-40% inhibition was observed for dna polymerase-b ... | 1978 | 274718 |
| chromosomal integration of phage lambda by means of a dna insertion element. | phage lambdacam112, which contains the chloramphenicol resistance transposon tn9 and has a deletion of attp and the int gene, will lysogenize escherichia coli k-12. prophage integration occurs at different chromosomal sites, including lacy and malb, but not at attb. all lambdacam112 prophages are excised from the chromosome after induction but with various efficiencies for different locations. heteroduplex analysis of lambdaplacz transducing phages isolated from a lacy::lambdacam112 prophage rev ... | 1978 | 274736 |
| autoclaving of lubricated dental instruments. | test organisms forced mechanically into lubricated, rotating dental instruments (handpieces) were all killed during autoclaving at 134 degrees c for 8 min, even when protected by serum and oil. the test organisms were: escherichia coli, staphylococcus aureus, pseudomonas aeruginosa, candida albicans, and spores of bacillus stearothermophilus. also when testing the sterility of autoclaved simulated instrument surfaces (brass cylinders and pieces of a cotton fabric) which had been inoculated with ... | 1978 | 274800 |
| mutations of bacteriophage t7 that affect initiation of synthesis of the gene 0.3 protein. | two different mutations that greatly diminish the rate of synthesis of the gene 0.3 protein of bacteriophage t7 have been characterized. one is in the initiator triplet for the 0.3 protein, changing it from aug to acg. this mutation was found to have little effect on binding of ribosomes to the 0.3 mrna in vitro, although 0.3 protein synthesis was greatly depressed in vitro as well as in vivo. a suppressor mutation that partially restores the wild-type rate of synthesis was found to lie within t ... | 1978 | 275843 |
| micrococcus luteus dna gyrase: active components and a model for its supercoiling of dna. | two active components alpha and beta of micrococcus luteus dna gyrase, of peptide weights of 115,000 and 97,000, respectively, have been purified. each individual component exhibits little dna gyrase activity; the atp-dependent negative supercoiling of a covalently closed circular dna duplex is catalyzed by a combination of the two. covalent closure by escherichia coli ligase of a circular dna containing single-chain scissions, when carried out in the presence of a combination of the dna gyrase ... | 1978 | 276855 |
| construction of a novel plasmid-phage hybrid: use of the hybrid to demonstrate cole1 dna replication in vivo in the absence of a cole1-specified protein. | a hybrid bacteriophage, p420, was constructed in vitro; it contains part of bacteriophage p4 and a 3.6-kilobase derivative of plasmid cole1. in escherichia coli, the plasmid-phage hybrid can exist as a stable plasmid or can be packaged into infective bacteriophage particles. replication of p420, directed by the cole1 replicon, was found to occur after p420 phage infection of e. coli cells that had been incubated in the presence of chloramphenicol. replication began without a lag period and resul ... | 1978 | 276860 |
| identification of the n gene protein of bacteriophage lambda. | the n gene protein, pn, of bacteriophage lambda stimulates early gene transcription by allowing mrna chain elongation to proceed into genes distal to transcription termination sites normally recognized by the escherichia coli transcription termination protein rho. pn has previously eluded detection on sodium dodecyl sulfate/polyacrylamide gels because of its small size, its instability, and the difficulty of distinguishing pn itself both from host proteins and from other early lambda proteins wh ... | 1978 | 276863 |
| genetic recombination and complementation between bacteriophage t7 and cloned fragments of t7 dna. | frafments of phage t7 dna have been cloned in escherichia coli by using the plasmid pmb9. such cloned fragments are able to recombine with infecting phages, thus providing a means to integrate the physical and genetic maps of t7 dna. approximately 65% of the t7 dna molecule has been found in clones so far, and analysis of these clones has mapped genes 12-17 with an accuracy of about 1% the total length of t7 dna. at least some cloned segments can supply t7 functions to infecting phages. | 1978 | 276868 |
| site-specific initiation of a dna fragment: nucleotide sequence of the bacteriophage g4 negative-strand initiation site. | the synthesis of the bacteriophage g4 negative strand is an example of the de novo initiation of a polynucleotide chain. this initiation is performed by the escherichia coli replication protein dna g which selects a unique site on 5400-base positive-strand template. in this paper we present the nucleotide sequence of the g4 negative-strand initiation site. this is the template element recognized by the dna g priming protein. in conjunction with the sequence of the nascent negative strand, obtain ... | 1978 | 277911 |
| transposition of plasmid dna segments specifying hydrocarbon degradation and their expression in various microorganisms. | the conjugative tol plasmid (75 mdal), specifying biodegradation of xylenes, toluene, and trimethylbenzene derivatives, undergoes dissociation in pseudomonas aeruginosa pao to a nonconjugative tol(*) plasmid (28 mdal) and a transfer plasmid termed toldelta (48 mdal). the tol(*) plasmid is rendered transmissible through introduction of a number of conjugative plasmids such as factor k, cam, and toldelta but not by the fp2 derivative pr0271. transfer of tol(*) via factor k or toldelta is mediated ... | 1978 | 277912 |
| enzymatic breakage of the cohesive end site of phage lambda dna: terminase (ter) reaction. | an in vitro system is described for measuring the endonucleolytic conversion of the phage lambda cohesive end sites in concatemeric dna to the cohesive chromosomal ends of the mature molecule. this enzymic process, known as the ter reaction, is catalyzed by purified lambda a gene protein. the reaction is markedly stimulated by atp, mg2+, spermidine, and one or more uncharacterized factors present in extracts of uninfected escherichia coli cells. in vitro, the ter reaction proceeds in the absence ... | 1978 | 279909 |
| efficient correction of a mutation by use of chemically synthesized dna. | the mutated base in the am3 lysis-defective mutant of the bacteriophage phix174 has been corrected by a combined in vitro enzymatic dna synthesis and in vivo replication of the heteroduplex product. chemically synthesized oligodeoxyribonucleotides carrying the wild-type sequence have been used to prime dna synthesis with am3 phix174 dna serving as a template. the resultant semisynthetic heteroduplex composed of an am3(+) strand and a wild-type (-) strand, with one mismatched base pair at positio ... | 1978 | 279913 |
| methods for the clinical evaluation of antibiotics in urinary tract infections. | antibiotic treatment of urinary tract infections is less than completely successful. factors involved in the outcome are complex and include host, bacterial and drug factors. eradication of the bacterial strain from the urine after the discontinuation of drug administration is a critical index in the clinical evaluation. categorical reports of in vitro bacterial susceptibility correlate poorly with clinical results. achievement of a bacterial inhibitory concentration of drug in the urine is esse ... | 1978 | 279983 |
| repair of o6-methylguanine in adapted escherichia coli. | cells exposed to sublethal concentrations of simple alkylating agents develop resistance to their mutagenic effects. this results from the induction of a system that we have called the adaptive response. during exposure to n-methyl-n'-nitro-n-nitrosoguanidine (mnng), escherichia coli cells induced for the adaptive response accumulate substantially less o6-methylguanine in their dna than control cells. if o6-methylguanine does form, adapted cells possess a repair system for removing it from their ... | 1978 | 282622 |
| a single base-pair change creates a chi recombinational hotspot in bacteriophage lambda. | x4+ mutations, responsible for the chi phenotype in phage lambda, locally increase the rate of recombination promoted by the escherichia coli recombination system (rec). x+ mutations in the cii gene, one of a few sites in lambda at which such mutations arise, were located genetically and physically with overlapping deletions. dna sequence analysis of the deletion segment containing the x+ c mutations showed that two independent x+ c mutations arose by the same a-t to t-a transversion. presumably ... | 1978 | 282634 |
| binding of hla antigen-containing liposomes to bacteria. | highly purified, detergent-solubilized hla-a and -b antigens and hla-d antigens were separately incorporated into liposomes. detergent-solubilized transplantation antigens, but not papain-solubilized antigens lacking the membrane-integrated portions of the molecules, were bound to the liposomes. a considerable portion of the liposome-bound antigens displayed accessible antigenic sites, suggesting that they were oriented in the right-side-out direction. liposomes containing the hla-a and -b antig ... | 1978 | 282637 |
| phosphate (oxygen)-water exchange reaction catalyzed by human prostatic acid phosphatase. | conclusive evidence is presented that an acid phosphatase catalyzes phosphate (oxygen)-water exchange. studies conducted with human prostatic acid phosphatase by two independent methods have established that, despite earlier reports to the contrary, the enzyme catalyzes an exchange reaction between oxygen atoms of phosphate ion and of water. kinetic data were obtained both by chemical conversion to trimethyl phosphate followed by mass spectroscopy and by a totally independent method involving 31 ... | 1978 | 283392 |
| mechanism of phage mu-1 integration: nalidixic acid treatment causes clustering of mu-1-induced mutations near replication origin. | frequencies of mu-1-induced mutants of escherichia coli have been compared under two different experimental conditions: cells in exponential growth and the same cells treated with nalidixic acid. the average of values obtained from the nalidixic acid-treated culture is 3 times higher than that obtained from the control. individual ratios of the frequency of mutants in the two cultures yield decreasing values from 6 to 1, starting from the point of origin of dna replication to the termini of dna ... | 1978 | 283404 |
| does 3'-terminal poly(a) stabilize human fibroblast interferon mrna in oocytes of xenopus laevis? | polynucleotide phosphorylase (polyribonucleotide:orthophosphate nucleotidyltransferase, ec 2.7.7.8) purified from escherichia coli was used enzymatically to deadenylate polyadenylated human fibroblast interferon mrna preparations obtained from human diploid fibroblasts (fs-4 strain) induced by poly(i)-poly(c) (20 microgram/ml) in the presence of cycloheximide (50 microgram/ml, 4 hr). both the polyadenylated and the deadenylated interferon mrna preparations were translated into biologically activ ... | 1978 | 283411 |
| subcellular localization of acyl carrier protein in leaf protoplasts of spinacia oleracea. | this communication demonstrates that all de novo fatty acid biosynthesis in spinach leaf cells requires acyl carrier protein (acp) and occurs specifically in the chloroplasts. antibodies raised to purified spinach acp inhibited at least 98% of malonyl coa-dependent fatty acid synthesis by spinach leaf homogenates. therefore, the presence of acp in a compartment of the spinach leaf cell would serve as a marker for de novo fatty acid biosynthesis. a radioimmunoassay capable of detecting 10(15) mol ... | 1979 | 286305 |
| regulation of the threonine operon: tandem threonine and isoleucine codons in the control region and translational control of transcription termination. | the dna sequence of 178 base pairs preceding the first structural gene of the threonine operon of escherichia coli has been determined. a region of perfect 2-fold rotational symmetry, involving 28 base pairs, precedes the first structural gene. the structural similarity of this sequence to known rna polymerase termination sites suggests that this region is the termination site of the threonine operon leader rna. moreover a mutation (thr 79-20), which confers a depressed, constitutive phenotype, ... | 1979 | 287010 |
| in vitro regulation of dna-dependent synthesis of escherichia coli ribosomal protein l12. | the dna of the transducing phage lambdarifd18 contains, among others, the genes for the ribosomal proteins l11, l1, l10, and l12 and the beta and beta' subunits of rna polymerase (nucleosidetriphosphate:rna nucleotidyltransferase, ec 2.7.7.6). in a coupled in vitro protein-synthesis system, lambdarifd18 dna directs the synthesis of about four to five molecules of l12 per molecule of l10. this is consistent with the finding that there are four copies of l12 per ribosome. the ratio of l12/l10 was ... | 1979 | 287012 |
| a chemotactic inhibitor produced by blast cells and present in the serum of a patient with acute lymphoblastic leukemia. | a chemotactic factor inhibitor (cfi) was found in the serum of a patient with acute lymphoblastic leukemia. the factor was characterized as heat-labile, with activity against complement-dependent chemotactic factors and against the chemotactic factor produced by escherichia coli. normal sera and sera from other patients with acute leukemia also demonstrate heat-labile inhibitory activity against complement-dependent chemotactic factors but not against the e. coli-derived chemotactic factor. supe ... | 1979 | 287518 |
| cloning of the t7 genome in escherichia coli: use of recombination between cloned sequences and bacteriophage t7 to identify genes involved in recombination and a clone containing the origin of t7 dna replication. | | 1979 | 289457 |
| human granulocyte function during dextran infusion. | the granulocyte function was determined in healthy persons before and immediately after the infusion of 500 ml of dextran for 4 hours. the nitroblue tetrazolium (nbt) reduction reflecting the metabolic activity of these cells was measured both in cells at rest and after stimulation with e. coli, as well as with and without the addition of plasma. in 13 persons, the nbt-reduction was slightly but significantly increased in all four types of experiments after the dextran infusion. when dextran was ... | 1979 | 291264 |
| electron microscopic analysis of partially replicated bacteriophage t7 dna. | partially replicated bacteriophage t7 dna was isolated from escherichia coli infected with uv-irradiated t7 bacteriophage and was analyzed by electron microscopy. the analysis determined the distribution of eye forms and forks in the partially replicated molecules. eye forms and forks in unit length molecules were aligned with respect to the left end of the t7 genome, and segments were scored for replication in each molecule. the resulting histogram showed that only the left 25 to 30% of the mol ... | 1979 | 291738 |
| structure of genes for human growth hormone and chorionic somatomammotropin. | a 2.6-kilobase (kb) ecori restriction endonuclease fragment containing human growth hormone (hgh; somatotropin) gene sequences and a 2.8-kb ecori fragment containing human chorionic somatomammotropin (hcs; choriomammotropin) gene sequences have been identified by hybridization to cloned cdna. human dna was cleaved with ecori and fractionated by preparative agarose gel electrophoresis; dna in the size range 2--3 kb was ligated to lambda gt wes.lambda b dna and viable recombinant bacteriophage wer ... | 1979 | 291965 |
| construction and cloning of rat albumin structural gene sequences. | a recombinant plasmid containing a dna segment complementary to rat liver albumin mrna has been constructed, cloned, and used to examine the organization of albumin gene. the 18s fraction of total liver poly(a)-containing rna was copied into a double-stranded cdna by avian myeloblastosis virus reverse transcriptase and escherichia coli dna polymerase i. the cdna was inserted into the hindiii site of the plasmid pbr322 via the addition of specific oligonucleotide linkers. recombinant plasmids wer ... | 1979 | 291970 |
| effect of intestinal bacteria on incidence of liver tumors in gnotobiotic c3h/he male mice. | the effect of intestinal microflora on liver tumorigenesis was studied in gnotobiotic c3h/he male mice monoassociated, diassociated, or polyassociated with the following strains of intestinal bacteria: escherichia coli, streptococcus faecalis, bifidobacterium adolescentis, bifidobacterium infantis, clostridium indolis, c. paraputrificum, c. perfringens, c. innocuum, c. nexile, c. ramosum, c. clostridiiforme, bacteroides multiacidus, bacteroides fragilis, veillonella alcalescens, v. parvula, and ... | 1979 | 292809 |
| origins of phage t4 dna replication as revealed by hybridization to cloned genes. | [3h]thymidine-labeled progeny dna was isolated after infection of escherichia coli with two different bacteriophage t4 mutants. these strands were isolated shortly after the initiation of dna replication and hybridized to 15 different (ecori) t4 restriction fragments cloned in plasmid vectors. uniformly labeled t4 [32p]dna extracted from phage particles was cohybridized as a normalizing reference. the results obtained lead to the conclusions that, among the loci tested, initiation occurs predomi ... | 1979 | 293710 |
| characterization of self-reactive b cells by polyclonal b-cell activators. | the existence of autoreactive b cells was predicted by theoretical considerations and, recently, confirmed by direct experiments. the aim of the present work was to investigate if the capacity of self-reactive b cells to be activated with different polyclonal b-cell activators (pba) reflects the heterogeneity of the response as seen in all the ig-positive cells. we injected mice with dextran sulfate, lipopolysaccharide from escherichia coli 055:b5, and purified protein derivate of turbercle bact ... | 1977 | 299768 |
| immunoprotective activity of ribosomes from haemophilus influenzae. | immunization with ribosomal preparations from haemophilus influenzae type b elicited protective immunity in mice. ribosomes from disrupted cells where isolated by differential centrifugation using sodium dodecyl sulfate. the washed ribosomes contained 25% protein and 75% ribonucleic acid and sedimented as a single peak on sucrose density gradient analysis with a sedimentation coefficient of 67s, using escherichia coli ribosomes as a 70s marker. immunodiffusion tests with antipolyribose phosphate ... | 1977 | 300360 |
| interaction of rna polymerase with promoters from bacteriophage fd. | replicative form dna of bacteriophage fd, which had been fragmented with the restriction endonuclease ii from hemophilus parainfluenzae (endo r- hpaii), was reacted with escherichia coli rna polymerase; the resulting stable preinitiation complexes were analysed using the filter binding assay followed by gel electrophoresis. at 120mm kcl the first-order rate constants for complex decay were determined to be 10(-2)-10(-6)s-1. the second-order rate constants for complex formation were found to be a ... | 1977 | 300680 |
| comparison of in vitro activity of cephalexin, cephradine, and cefaclor. | inhibitory activity of cephalexin, cephradine, and cefaclor was compared by the who-ics agar dilution technique. cefaclor was substantially more active against staphylococci, streptococci, gonococci, meningococci, haemophilus, escherichia coli, klebsiella pneumoniae, citrobacter diversus, proteus mirabilis, salmonellae, and shigellae than was cephalexin, which in turn was more active than cephradine. cefaclor appeared to be less resistant to staphylococcal penicillinase than did the other two ag ... | 1977 | 301005 |
| bactericidal factor produced by haemophilus influenzae b: partial purification of the factor and transfer of its genetic determinant. | when aerobically grown on complex media, haemophilus influenzae b and unencapsulated variants, rb strains, produced a bactericidal factor that was active against other haemophilus species and certain genera of the enterobacteriaceae. a total of 341 clinical isolates of haemophilus were tested for susceptibility to the factor. ninety-three percent of h. influenzae (nontypable), 75% of h. haemolyticus, 71% of h. parainfluenzae, and 22% of h. parahaemolyticus were susceptible. h. influenaze b strai ... | 1977 | 301008 |