| biological effects of escherichia coli lipopolysaccharide (lps) in vivo. i. selection in the mouse thymus of killer and helper cells. | in the present study we have investigated the biological effects on thymus lymphocytes resulting from escherichia coli lipopolysaccharide (lps) treatment in young adult mice. it has been established that lps induces the following effects: (a) a dose-dependent reduction of thymus weight contemporaneous with a rise in the anti-lps antibody response; (b) an increase of killer activity of thymus cells; (c) an enhancement of thymocytes helper activity; (d) a reduction of theta-positive cells in the t ... | 1976 | 8378 |
| formation of mutagenic n-nitroso compounds from the pesticides prometryne, dodine and carbaryl in the presence of nitrite at ph 1. | environmental chemicals including pesticides carrying secondary and tertiary amino groups are suggested to be a health hazard to man since potentially carcinogenic nitroso compounds may be formed in the presence of nitrite at low ph values resembling conditions in the human stomach. nitrosation of the isopropylamino-triazine prometryne, the n-dodecyl guanidine dodine and the n-methylcarbamate carbaryl was investigated in the presence of hcl and acetic acid at ph 1 and excess sodium nitrite for 4 ... | 1976 | 12468 |
| differential susceptibility of escherichia coli and proteus mirabilis to mouse urine and to urea. | the purpose of this investigation was to compare the antimicrobial properties of mouse urine and of urea against escherichia coli and proteus mirabilis. nornal urine was found to inhibit the growth of e. coli and p. mirabilis, whereas urine from diuresing animals permitted multiplication of these bacteria. addition of urea to urine from diuresing animals restored its bactericidal effect on p. mirabilis but not on e. coli. this bactericidal effect on p. mirabilis was dependent on the additive act ... | 1977 | 18546 |
| some effects of the administration of endotoxin in mice. specific cleavage of serum albumin by an acid protease and the generation of amyloid serum component. | endotoxin has been shown to induce amyloidosis in mice and to result in the appearance in serum of large amounts of amyloidrelated protein (saa). after injection of 300 mug lipopolysaccharide escherichia coli, saa behaves as an acute phase reactant with levels reaching a peak of >600 mug/ml at 18-22 h and returning to base line (<50 mug/ml) by 48 h in each of four strains tested; only the endotoxin-resistant c3h/hej strain showed a smaller response. lesser, though significant, elevations were al ... | 1979 | 34628 |
| production of heat-stable, methanol-soluble enterotoxin by yersinia enterocolitica. | seven isolates of yersinia enterocolitica serotype 0:8, recovered during an outbreak of gastrointestinal illness, were examined for enterotoxin production. all seven strains were enterotoxigenic in the suckling mouse model, and three of five isolates tested produced keratoconjunctivitis in the guinea pig eye model (sereny test). enterotoxin was detected in broth supernatant fluid after 12 h of incubation at 25 degrees c. the toxin was not inactivated by exposure to 121 degrees c for 30 min or by ... | 1979 | 39891 |
| [an oral enteritis-vaccine composed of twelve heat inactivated enterobacteriaceae. 1. communication: theoretical and epidemiological considerations (author's transl)]. | the infectious diseases of the human intestinal tract which are caused by bacteria must be distinguished into two groups on account of their different pathogenesis: the cyclic infections (typhoid fever, parathyphoid fever) and the local infections (cholera, dysentery, salmonella enteritis, dyspepsia coli infections). the local infections of the intestine do not cause a systemic but only a local immunity of the intestinal mucosa. it is necessary therefore to induce local immunity as active immuno ... | 1979 | 44783 |
| urinary-tract infection: localisation and virulence of escherichia coli. | virulence of 15 strains of escherichia coli from the human upper urinary tract was compared with that of 16 strains from the lower urinary tract, using an ascending infection in the mouse. no significant difference was found. there was no significant difference in frequency of k antigen and ability to ferment dulcitol between 32 lower strains and 31 upper strains. however, 22 strains containing k antigen, regardless of anatomical site of localisation, were more significantly likely to cause infe ... | 1975 | 46051 |
| inhibition of the lethality of bleomycin a5 in l-cells by hirudonine. | the lethality of several individual bleomycin derivatives, i.e., the spermidine derivative (a5), the dimethyl sulfonium aminopropyl derivative (a2), and the agmatine derivative (b2), was compared on mouse fibroblasts. the spermidine derivative, bleomycin a5, was the most toxic, producing more than a 2-log drop in clonability in 50 hr at 20 microng/ml. 6-azauridine, a relatively nonlethal inhibitor of rna synthesis and cell multiplication, produced a 60% decrease of adenine incorporation into nuc ... | 1977 | 66981 |
| enterotoxigenic escherichia coli and reovirus-like agent in rural bangladesh. | 48 patients admitted to a rural bangladesh hospital with dehydration secondary to diarrhea were examined for infection caused by (r.l.a.) reovirus-like agent or (e.t.e.c.) enterotoxigenic escherichia coli. the diagnosis of r.l.a. infection was established by electron microscopy of stool filtrates and by a 4-fold or greater rise in serum complement-fixing antibodies to the nebraska calf diarrhea virus. evidence of infection by heat-labile-toxin producing e.t.e.c. was sought by stool culture and ... | 1976 | 73638 |
| escherichia coli strains that cause diarrhoea but do not produce heat-labile or heat-stable enterotoxins and are non-invasive. | three enteropathogenic escherichia coli (e.p.e.c.) strains (o127:k63:h6, o128:k67:h2, and o142:k86:h6) isolated from outbreaks of infantile diarrhoea and one strain from the "normal" colonic flora (e. coli hs) of a healthy adult were fed in doses of 10(6), 10(8), and 10(10) organisms in nahco3 to adult volunteers. the strains, which had been stored for 7--9 years, gave negative results in sensitive tests for heat-labile (l.t.) enterotoxin (y-1 adrenal-cell test), heat-stable (s.t.) enterotoxin ( ... | 1978 | 77415 |
| detecting enteropathogenic strains of escherichia coli of porcine origin. 2. relationship between o and k antigens and the production of enterotoxin in strains isolated from the piglet after weaning. | the production of enterotoxin by biological tests (yl adrenal cells and the suckling mouse) has been examined in 96 strains of escherichia coli, isolated from sick piglets after weaning. there is a good correlation between the presence of the capsular antigen k88 and that of the thermolabile fraction (lt) of the enterotoxin (69.2 per cent of the enteropathogenic strains studied). however, the presence of the thermostable fraction (st) of the enterotoxin of strains which, according to their serol ... | 1978 | 86320 |
| the presence of intervening sequences in the alpha-fetoprotein gene of the mouse. | | 1979 | 88451 |
| induced synthesis of immunoglobulin messenger rna accompanies induction of immunoglobulin production in cultured mouse spleen cells. | immunoglobulin kappa type light chain mrna (lkappa mrna) accumulated in parallel with secretion of immunoglobulin m in cultured mouse spleen cells activated by lipopolysaccharide. actinomycin d suppressed the accumulation of kappa chain mrna completely without affecting the degradation rate of kappa chain mrna. the half life of kappa chain mrna was about 9 h. available evidence indicates that lipopolysaccharide stimulates de novo synthesis of kappa chain mrna. the accumulation of kappa chain mrn ... | 1978 | 103878 |
| mitogen-stimulated glutaraldehyde-fixed spleen cells: ability to stimulate in the mixed lymphocyte reaction and generate effector cells in cell-mediated lympholysis. | mouse spleen cells treated with glutaralde lose their stimulating ability in the mlr. if the spleen cells are first converted to a blastogenic state by lipopolysaccharide and subsequently fixed with glutaraldehyde, their stimulating capacity is maintained. | 1976 | 135809 |
| feasibility of enterochelin as an iron-chelating drug: studies with human serum and a mouse model system. | | 1978 | 149036 |
| 2'-o-methylated oligonucleotides in ribosomal 18s and 28s rna of a mouse hepatoma, mh 134. | simple two-dimensional thin-layer chromatography was found to be useful for the separation of sugar methylated dinucleotides in rna. of the 16 possible sequences of the type nm-np, 15 were separated and all the sequences were determined. in a mouse hepatoma, mh 134, the levels of the sugar methylation in the 18s and 28s rna molecules were 17-18 and 11-12 per 1000 nucleotides, respectively. thus, 18s rna contained approximately 35 2'-o-methylated dinucleotides and 28s rna approximately 60 2'-o-me ... | 1975 | 164900 |
| mapping of the sv40 specific sequences transcribed in vitro from chromatin of sv40 transformed cells. | chromatin was isolated from sv40 transformed mouse cells (sv3t3) and transcribed with escherichia coli rna polymerase. the sv40 specific transcripts were analyzed by annealing the rna to the minus strands of purified fragments of sv40 dna produced by cleavage of the dna with a restriction enzyme isolated from hemophilus aegyptius. quantitation of the frequency of transcription from the region (fragments a and d) was transcribed five to ten times more frequently than the remaining regions. these ... | 1975 | 167804 |
| temperature dependence of strand separation of the dna molecules containing integrated sv40 dna in transformed cells. | it has previously been demonstrated that the dna molecules containing a genetic marker from one region of a bacterial genome undergo complete strand separation at temperatures usually different from the molecules containing a genetic marker from another region of the genome. the experiments also showed that if a group of molecules undergo complete strand separation over a narrow temperature range, of the order of one to three degrees, it is highly likely that they all come from one region of the ... | 1975 | 170596 |
| orientation of the complementary strands of polyoma virus dna with respect to the dna physical map. | the chemical polarities of the two strands of polyoma virus dna with respect to the dna physical map have been determined by hybridization of restriction endonuclease fragments specifically labeled with [125i]dcmp at their 3' termini to asymmetric polyoma complementary rna (the product of in vitro transcription of viral dna by escherichia coli rna polymerase). the orientations of the polyoma-specific stable rna transcripts present in the cytoplasm of productively linfected mouse cells have been ... | 1975 | 173885 |
| interferon-producing capacity of germfree mice. | the general capacity of germfree mouse spleen cells to produce interferon in vitro in response to various stimuli was investigated. the interferon response of germfree mouse spleen cells in vitro, when compared with that of the conventionals, appears to be lower to some inducers. interferon production in vitro stimulated by hemagglutinating virus of japan (hvj) or bhk-hvj cells (bhk cells persistently infected with hvj) was apparently suppressed in germfree mouse spleen cells as compared with th ... | 1976 | 177363 |
| synthesis and biological studies of 3-(beta-d-ribofuranosyl)-2,3,-dihydro-6h-1,3-oxazine-2,6-dione, a new pyrimidine nucleoside analog related to uridine. | reaction of the trimethylsilyl derivative of 2,3-dihydro-6h-1,3-oxazine-2,6-dione (2, "uracil anhydride") with protected 1-o-acetylribofuranoses in the presence of stannic chloride gave the corresponding block nucleosides. 3-(2,3-5-tri-o-2',2',2'-trichloroethoxycarbonyl-beta-d-ribofuranosyl)-2,3-dihydro-6h-1,3-oxazine-2,6-dione (4c) thus prepared from the protected sugar 3c, 1-o-acetyl-2,3,5-tri-o-(2,2,2-trichloroethoxycarbonyl)ribofuranose, gave, on removal of the protecting groups with zinc du ... | 1976 | 178870 |
| isolation of a lipid a bound polypeptide responsible for "lps-initiated" mitogenesis of c3h/hej spleen cells. | the experiments by sultzer and nilsson (1), and later by watson and riblet (2), established that spleen cells from the c3h/hej strain of mouse were refractory to the mitogenic effects of bacterial lipopolysaccharides (lps). more recently, however, experiments from our laboratory (3) demonstrated that spleen cells from c3h/hej mice were in fact responsive to some preparations of lps but not to others, and that the method of extraction played a critical role in determining activity. in particular, ... | 1976 | 182900 |
| transfer of trnas to somatic cells mediated by sendai-virus-induced fusion. | trnas from yeast (trnaphe and 4s rna) and escherichia coli (suiii+ trnaityr) have been transferred to mouse cells by means of a two-step transfer procedure [loyter, zakai, and kulka (1975) j. cell biol. 66, 292-304; schlegel and rechsteiner (1975) cell 5, 371-379]. in the first stage of the transfer trnas were incorporated into rabbit red blood cells (rbcs). thereafter, the loaded erythrocytes were fused with recipient mouse cells by means of sendai virus. at least 0.3-0.4% of the total input of ... | 1976 | 183211 |
| characterization of surface glycoproteins of mouse lymphoid cells. | we have labeled exposed surface glycoproteins of mouse lymphoid cells by the galactose oxidase-tritated sodium borohydride technique. the labeled glyco-proteins were separated by polyacrylamide slab gel electrophoresis and visualized by autoradiography (fluorography). the major thymocyte surface proteins have molecular weights of 170,000 and 125,000. thymocytes from tl antigen-positive mouse strains showed an additional band with a molecular weight of 27,000. highly purified t lymphocytes contai ... | 1976 | 192730 |
| mitogenic response of mouse spleen cells and gelation of limulus lysate by lipopolysaccharide of yersinia pestis and evidence for neutralization of lipopolysaccharide by polymyxin b. | lipopolysaccharide (lps) extracted with phenol and water from yersinia pestis was compared with lps of escherichia coli for stimulation of deoxyribonucleic acid synthesis in mouse spleen cells (lymphocyte mitogenesis), gelation of limulus lysate, pyrogenicity in the rabbit, and susceptibility to inhibition of these activities by polymyxin b sulfate (pbs). lps of y. pestis stimulated deoxyribonucleic acid synthesis in mouse spleen cell cultures over the same quantitative range as lps of e. coli. ... | 1977 | 200563 |
| [induction of antibodies to native dna by components of bordetella pertussis]. | administration of bordetella pertussis and some of their components to mice induced an increase of dna-binding activity of the sera revealed under ionic strength conditions of physiological saline, mostly on the 14th day. it was shown by the inhibition method that interaction between mouse sera and native dna was specific. maximum increase in the quantity of mouse sera proteins reacting with dna under low ionic strength condition of physiological saline (0.05 m nacl) is revealed on the 7th day. ... | 1978 | 210865 |
| glycoproteins of natural origin with an affinity for hepatitis b surface antigen. | sera from certain animal species contain a substance(s) which binds hepatitis b surface antigen. the hepatitis b binding substance found in animals is not antibody, but appears to be a glycoprotein which reacted with antigen-coated beads and produced a "false positive" test for antibody. this glycoprotein could be selectively and quantitatively removed by reaction with purified hepatitis b surface antigen and centrifugation. pili fractions isolated from neisseria gonorrhoeae and escherichia coli ... | 1978 | 213390 |
| molecular cloning of polyoma virus dna in escherichia coli: plasmid vector system. | a series of recombinant plasmids containing polyoma virus (py) dna were constructed, and their biological activity was evaluated in mice and in cultured mouse cells. while all of the recombinants studied contain the complete, potentially infectious viral dna, in no case was the intact recombinant py-plasmid dna, or live escherichia coli containing the recombinant plasmids, capable of inducing py infection of mice, either by feeding or by parenteral injection. | 1979 | 217087 |
| molecular cloning of polyoma virus dna in escherichia coli: oncogenicity testing in hamsters. | inoculation of suckling hamsters with 2 x 10(8) live cells of escherichia coli k12 strain chi1776, carrying the complete genome of polyoma virus in a recombinant plasmid, failed to induce tumors in any of 32 recipients. also, lambda phage dna and particles with a monomeric insert of polyoma dna did not induce tumors. purified recombinant plasmid dna, as well as phage particles and dna containing a head-to-tail dimer of polyoma dna, showed a low degree of oncogenicity, comparable to that of polyo ... | 1979 | 224458 |
| cloning of the active thymidine kinase gene of herpes simplex virus type 1 in escherichia coli k-12. | a herpes simplex virus dna fragment that is produced by digestion with bamhi endonuclease and carries the thymidine kinase (tk; atp:thymidine 5'-phosphotransferase, ec 2.7.1.21) gene has been cloned in escherichia coli. a recombinat plasmid, pfg5, has been analyzed extensively and a detailed restriction map is presented. pfg5 dna efficiently transforms tk- mouse l cells. the tk coding sequence in the cloned fragment has been localized and a smaller recombinant plasmid, pag0, also carrying an act ... | 1979 | 226978 |
| protection of mice against infection with wild-type mengo virus and an interferon sensitive mutant (is-1) by polynucleotides and interferons. | single-stranded polynucleotide preparations [trna, poly(ri) plus poly(ho5c)-copolymer] which protect mice against picornavirus infections without inducing interferon, protected mice equally against infection with an interferon-sensitive mutant (is-1) of mengo virus and with wild-type virus (is+). poly(ri) . poly(rc), and mouse macrophage interferon [i.e. serum from mice treated with poly(ri) . poly(rc)] protected mice equally against infections with the two viruses, but fibroblast interferon pro ... | 1979 | 227997 |
| assay, characterization, and localization of an enterotoxin produced by salmonella. | an enterotoxic factor isolated from cultures of salmonella yielded reproducible results in the suckling mouse model in contrast to other animal models. the enterotoxin appears to possess properties similar to both the heat-stable and heat-labile enterotoxins of escherichia coli. preliminary results indicate that the toxin is a protein, is located in the cell wall or outer-membrane fraction, and is difficult to separate from other cell wall constituents. | 1975 | 234910 |
| 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 |
| 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 |
| in vitro transcription of moloney leukemia virus genes in infected cell nuclei and chromatin: elongation of chromatin associated ribonucleic acid by escherichia coli ribonucleic acid polymerase. | the in vitro transcription of viral specific dna sequences in nuclei and chromatin isolated from mouse cells chronically infected with moloney murine leukemia virus (mo-mulv) has been studied. the in vitro rna synthesized by escherichia coli rna polymerase has been isolated by sulfhydryl affinity column following reaction in the presence of 5-mercuriuridine triphosphate. by comparison of the crt curves of the in vitro rna with that of 70s viral rna, the content of viral sequences is found to be ... | 1977 | 322707 |
| bacterial lipopolysaccharide induction of a mouse spleen factor stimulating ribonucleic acid polymerase ii. | when bacterial lipopolysaccharide, a b-cell mitogen, was injected intraperitoneally into mice, the rate of deoxyribonucleic acid synthesis and the number of antibody-secreting cells in the spleen increased simultaneously, reaching a maximum in 3 days. the rate of ribonucleic acid synthesis also increased during this period, and this was found to be due to activation of alpha-amanitin-sensitive transcription in lymphoid cells of the spleen. the factors stimulating ribonucleic acid polymerase ii i ... | 1977 | 324912 |
| the sequence specificity of a mammalian dna methylase. | the sequence specificity of an extensively purified dna methylase preparation from krebs ii mouse ascites cells has been examined. the enzyme appears to be highly sequence dependent. moreover the sequence distribution of cytosine residues that are methylated, bears a very close resemblance to the sequence distribution of 5'-methyl cytosine found in vivo in a wide range of vertebrate cells and is consistent with methylation of cytosines in the sequence r-yn-c-r. | 1977 | 325523 |
| enhanced lysosomal enzyme activity in mouse cells treated with bacterial endotoxin in vitro. | | 1977 | 327485 |
| restriction endonuclease cleavage maps of rat and mouse mitochondrial dnas. | mitochondrial dna from an old world mouse, mus musculus, and from an old world rat, rattus norvegicus, contain 19 and 22 distinct sites, respectively, for the 8 restriction endonucleases, bamhi, ecori, haeii, hhai, hincii, hindiii, hpai and psti. the relative positions of the sites have been mapped by the study of partial and double enzyme digests. some sites may been conserverd between the mouse and rat mitochondrial genomes. | 1977 | 331254 |
| microheterogeneity detected in circular dimer mitochondrial dna. | exhaustive ecori digests of circular dimer mitochondrial dna (mtdna) from mouse cell lines ld and ldtk- yield two major fragments whose average lengths are slightly smaller than the corresponding fragments of circular monomer mtdna from mouse la9 and lmtk- cells. a third fragment approximately 400 nucleotide pairs in length is frequently produced in less than molar yield. exhaustive ecori digests of circular dimer mtdna from human acute myelogenous leukemic leucocytes yield three major fragments ... | 1977 | 331255 |
| cyclacillin-induced potentiation of escherichia coli immunogenicity in vivo and in vitro. | the efficacy of cyclacillin as an antimicrobial agent against escherichia coli was assessed in vivo in mice infected with low numbers of bacteria and compared to the relative effectiveness of the antibiotic against the same organisms in vitro. treatment of mice with cyclacillin resulted in a rapid clearance of e. coli from the blood and their greater killing in the spleen and liver. furthermore, a significantly higher antibody plaque response against e. coli developed in cyclacillin-treated mic ... | 1977 | 332464 |
| escherichia coli heat-labile enterotoxin: comparison of antitoxin assays and serum antitoxin levels. | the mouse adrenal tumor cells (y-1 strain) and the chinese hamster ovary cells, two routinely used tissue culture assays for escherichia coli heat-labile enterotoxin (lt), were used to detect serum antitoxin responses in culture-positive patients from several well-defined sources. there was no correlation between a significant antitoxin response and isolation of lt-producing e. coli in two "domestic" diarrheal outbreaks. serum samples from a third group of individuals in a rural cholera-endemic ... | 1977 | 336543 |
| role of t and adherent cells in in vitro response of nude mouse spleen cells to bacterial lipopolysaccharide. | thy 1.2-positive cells and adherent cells were depleted from nude mouse spleen cell suspensions by treatment with anti-thy 1.2 antisera plus complement and by passage through sephadex g-10 column, respectively. the results of 3h-tdr uptake and appearance of igm containing cells induced in vitro by lipopolysaccharide (lps) were similar in both untreated and depleted spleen cells. our findings confirm t and adherent cell independence of lps response in nude mice. | 1977 | 338502 |
| questioning of reported evidence for guanosine tetraphosphate synthesis in a ribosome system from mouse embryos. | in 1974, irr, kaulenas and unsworth reported that ppgpp is synthesized by cytosolic ribosomes from mouse embryos and proposed a role for ppgpp in the process of differentiation. this proposal is being challenged because ribosomes of mouse embryos from various stages of development and of mouse embryoid bodies were completely inactive in ppgpp formation. | 1977 | 340046 |
| antibody formation in mouse bone marrow. vi. the regulating influence of the spleen on the bone marrow plaque-forming cell response to escherichia coli lipopolysaccharide. | | 1977 | 344201 |
| differential effects of polyadenylic: polyuridylic acid and lipopolysaccharide on the generation of cytotoxic t lymphocytes. | in a mixed leukocyte culture (mlc) reaction of allogenic mouse spleen cells differing for h-2k or h-2d, only a weak cytotoxic response is generated. this cytotoxic response is augmented significantly if bacterial lipopolysaccharide (lps), 5 microgram/ml, or polyadenylic acid (poly a):polyuridylic acid (poly u), 20 microgram/ml, is present in the culture. the cytotoxic cells generated in the presence of these two agents are specific for sensitizing h-2k or h-2d antigen. two lines of evidence sugg ... | 1978 | 349110 |
| escherichia coli infection in mice and impaired fetal development. | investigations were undertaken, using the mouse as an animal model, to study the effect of escherichia coli on fetal development. the i.v. injection of 7.5 x 10(6) bacteria, originally obtained from a suspected case of human pyelonephritis, caused only a mild and transient disturbance of maternal health but caused severe fetal wastage. groups of mice were examined 4, 7 and 11 days after infection and the numbers of organisms were determined in the spleen, liver, kidneys, placentas and resorption ... | 1978 | 354680 |
| [dynamics of biologically active enterotoxin release by e. coli]. | accumulation of e. coli enterotoxin in the finkelshtein's culture medium in growing the cells in a 30-litre reactor was studied. accumulation of active highly molecular enterotoxin occurred in the course of a 6-hour cultivation of e. coli, strain p-99 (o141: k85ab; k88ab: h4) in the fluid medium under aeration. oxygen utilization, synthesis and release into the nutrient medium of pyruvic acid, and protein accumulation were observed. the preparation obtained was stable to the lyophylic drying, co ... | 1978 | 358698 |
| phenotypic expression in e. coli of a dna sequence coding for mouse dihydrofolate reductase. | the construction and analysis of bacterial plasmids that contain and phenotypically express a mammalian genetic sequence are described. such plasmids specify a protein that has enzymatic properties, immunological reactivity and molecular size characteristic of the mouse dihydrofolate reductase, and render host cells resistant to the antimetabolic drug trimethoprim. | 1978 | 360074 |
| enterotoxigenicity of enteropathogenic serotypes of escherichia coli isolated from infants with epidemic diarrhea. | enteropathogenic serotypes of escherichia coli which have been incriminated by epidemiological evidence as responsible for epidemics of acute diarrhea in infants are often found to be nontoxigenic when tested by conventional systems such as y1-adrenal, chinese hamster ovary, and suckling mouse assays. twelve such strains, representing four different enteropathogenic serotypes, were examined for their capacity to elaborate toxic materials which alter water transport. ultrafiltration fractions pre ... | 1978 | 361562 |
| the effect of colonization of the mouse mammary gland by staphylococcus epidermidis on subsequent infection with staphylococcus aureus or escherichia coli. | | 1978 | 361766 |
| specific interaction between mouse liver non-histone chromosomal proteins and mouse dna demonstrated by a sequential dna-protein binding procedure. | the binding of mouse liver chromosomal proteins to dna has been investigated using the nitrocellulose filter binding technique. careful purification of the dna involving nuclease s1 digestion and prefiltration through a nitrocellulose filter is used to reduce background binding in the absence of protein to less than 1%. procedures involving direct binding of protein to labeled dna, competition of binding of labeled dna by unlabeled dna, and dissociation of dna . protein complexes with time do no ... | 1978 | 363155 |
| potential toxicity of materials used for home insulation. | the two aqueous solutions used for production of residential home insulation by the so-called urea-formaldehyde process were tested for their ability to react with cellular macromolecules. one of the components (the catalyst-surfactant) changed the apparent molecular weight of isolated dna and increased its rate of attachment to bacterial and animal cells. the other component (the formaldehyde-urea resin) showed both these activities, especially following its exposure to mouse or rat liver extra ... | 1978 | 365512 |
| dna release as a direct measure of microbial killing by phagocytes. | a new assay for the precise measurement of microbial killing by leukocytes is presented. the method assumes that release of radioactively labeled dna from the microbe is direct evidence of cell death. human peripheral blood leukocytes incubated with [14c]thymidine-labeled salmonella typhimurium released 32 to 59% of the radioactivity after 4 h and 63 to 75% after 18 h. inactivated leukocytes released less than 5% of the radioactivity. none of the released radioactivity is retained within the leu ... | 1978 | 365741 |
| characterization of a congenitally lps-resistant, athymic mouse strain. | c57bl/10scn (nu/nu) mice have b cells and macrophages unresponsive to a phenol-water extracted preparation of escherichia coli k 235 lps. this unresponsiveness was demonstrated in vitro by the inability of spleen cells to incorporate 3h-thymidine after a 48 hr incubation with lps (ph) and by the inability of lps (ph) to inhibit macrophage phagocytosis of 51 cr-labeled, opsonized sheep erythrocytes. furthermore, macrophage cultures stimulated with lps (ph) produced low levels of laf and pge2 when ... | 1979 | 368244 |
| a comparison of the effects of endotoxin upon fibroblast proliferation and macromolecular syntheses. | the effects of escherichia coli endotoxin upon mouse l929 cell proliferation, dna synthesis, protein synthesis, and proline incorporation were determined. it was found that a level of endotoxin which inhibited cell proliferation prompted a similar inhibition of dna synthesis and overall cell protein synthesis. in contrast, endotoxin was shown to inhibit incorporation of proline into cell protein to a significantly greater extent. | 1979 | 376570 |
| the binding of lps to the lymphocyte surface. | bacterial lipopolysaccharide (lps) from escherichia coli labelled with tritium has been used to follow the binding of lps to lymphocytes. binding to cells rose to a maximum 2-7 min after addition of [3h]-lps, followed by loss of [3h]-lps from cells, reducing to about 10% of the peak level at 20-30 min. peripheral blood lymphocytes, mesenteric lymph node and thymus cells of the pig and cba, c3h/he and c3h/hej mouse spleen cells all bound [3h]-lps transiently at similar levels. it is concluded tha ... | 1979 | 391698 |
| some biological characteristics of escherichia coli strains isolated from acute diarrhoeal diseases of infants. | the aim of this study was to evaluate the methods of biological characterization of escherichia coli strains, in order to use them as screening tests in clinical microbiological laboratories. in two thirds of the 45 e. coli, isolated from acute intestinal infection of infants, different factors of virulence were found. the strains showed prevalently an enterotoxigenic character (66,6%), which was in correlation with the increased permeability (62,2%). adhesive properties were present in 20% of e ... | 1979 | 396738 |
| excision of uracil from bromodeoxyuridine-substituted and u.v.-irradiated dna in cultured mouse lymphoma cells. | a uracil-dna glycosylase activity was detected in cell-free extracts from cultured mouse lymphoma l5178 cells. we investigated whether or not this enzyme plays a role in the removal of uracil from chromosomal dna. u.v. light (254nm) irradiation of the cells with budr-substituted dna produced not only single-strand breaks but also 'internal' uracil residues that were recognized as substrate sites by uracil-dna glycosylase. these 'internal' uracil residues were lost from the dna upon reincubation ... | 1979 | 397940 |
| protein expression in e. coli minicells by recombinant plasmids. | the polypeptides synthesized in e. coli minicells from recombinant plasmids containing dna fragments from cauliflower mosaic virus, drosophila melanogaster, and mouse mitochondria were examined. molecularly cloned fragments of cauliflower mosaic virus dna directed the synthesis of high levels of three polypeptides, which were synthesized entirely from within the cloned virus dna fragments independent of their insertion into the plasmid vehicles. several fragments of d. melanogaster dna were capa ... | 1977 | 403011 |
| assay of escherichia coli heat-labile enterotoxin with vero cells. | the continuous cell line of african green monkey kidney, vero, showed characteristic morphological changes in response to culture filtrates from toxigenic strains of escherichia coli. the response compared favorably with that of y-1 (mouse adrenal) and cho (chinese hamster ovary) cells. vero cells were the simplest and most economical to maintain in the laboratory. | 1977 | 405326 |
| the identification of six mouse lymphocyte subpopulations by their natural binding of bacteria. | | 1978 | 415087 |
| mutagenic evaluation of clonazepam using in vitro and in vivo bacterial tests. | the mutagenicity of an anti-epileptic drug, clonazepam, and its metabolites was studied by three repair (rec, pol and uvr) assays and reversion (ames') tests. no detectable induction of mutation could be found in any tests by them per se or via metabolism in rat and mouse. | 1978 | 417244 |
| production of enterotoxin by yersinia enterocolitica. | forty-three strains of yersinia enterocolitica isolated from children with gastroenteritis and 18 laboratory strains were examined for enterotoxin production by using the infant mouse, y1 adrenal cell, and rabbit ileal loop assay systems. all clinical isolates and seven laboratory strains were found enterotoxigenic in the infant mouse model, but none of the strains produced toxin in the y1 adrenal cell system. one enterotoxin-producing strain was also tested by the rabbit ileal loop assay, confi ... | 1978 | 640737 |
| characterization of the acidic phosphorprotein of eukaryotic ribosomes using a new system of two-dimensional gel-electrophoresis. | 1. a modified method of two-dimensional gel electrophoresis has been developed for detecting acidic eukaryotic ribosomal proteins. 2. using this method it has been demonstrated that the major phosphoprotein (lgamma) of mouse ascites and hamster fibroblast 60-s ribosomal subunits is an acidic protein, apparently analagous to l7/12 of escherichia coli, and not a neutral protein as previously thought. electrophoretic resolution of phosphorylated and non-phosphorylated forms of lgamma has enabled th ... | 1978 | 667063 |
| antibody formation in mouse bone marrow. v. the response to the thymus-independent antigen ecsherichia coli lipopolysaccharide. | the occurrence of plaque-forming cells (pfc) in mouse bone marrow was studied during primary and secondary responses to the thymus-independent antigen escherichia coli lipopolysaccharide (lps). anti-lps responses were induced by various doses of lps. during the primary response, doses of 1 and 10 mug lps intravenously (i.v.) were found to evoke a distinct pfc response in both spleen and bone marrow. the spleen contained the majority of pfc until about 5 days after immunization. during the course ... | 1976 | 765265 |
| investigation of the effect of k antigen in escherichia coli urinary tract infections by use of a mouse model. | urinary infection could be produced in mice by the inoculation of escherichia coli into the bladder, provided that sutures had first been inserted into the bladder wall to act as foreign bodies. while the bladder was almost always infected, thekidneys were involved less often. the frequency of kidney infection was directly proportional to the k antigen of the infecting strain of e. coli. the significance of k antigens in relation to host defence mechanisms and tissue invasion is discussed. | 1975 | 769819 |
| salmonellosis in mice: immunization experiments with salmonella-escherichia coli hybrids. | mice vaccinated with escherichia coli hybrids experesing salmonella o antigens were protected against lethal challenge doses of salmonella strains. counts of challenge bacteria in mouse organs revealed that a live hybrid vaccine was slightly more efficient than an acetone-killed vaccine. | 1976 | 773838 |
| mouse spleen lymphocyte bactericidal and peroxidase activities: enhancement by whole body x-irradiation. | a 20,000 g pellet obtained from the homogenate of cd1 mouse spleen cells has measurable peroxidase and bactericidal activities. whole body x-irradiation stimulates the in vitro peroxidative and bactericidal activities of the spleen cells. these cells do not phagocytize. however, addition of polystyrene latex particles to spleen cells from non- or x-irradiated mice, increases glucose oxidation. the extent of this stimulation (three- to fourfold) is less than that of pmn (six- to tenfold). interac ... | 1976 | 778856 |
| influence of certain indigenous gastrointestinal microorganisms on duodenal alkaline phosphatase in mice. | alkaline phosphatase activity was assayed in duodenal homogenates or extracts from adult specific pathogen-free (spf) and germfree mice and gnotobiotic mice monoassociated with a lactobacillus sp., a bacteroides sp., or a coliform strain indigenous to spf mice. activity levels of the enzyme were much higher in the preparations from germfree mice than in those from the spf controls. in the gnotobiotes monoassociated either with a freshly isolated lactobacillus sp. or a bacteroides sp., the levels ... | 1976 | 779647 |
| activity of stringent protein in ribosomes of escherichia coli during the growth cycle. | to investigate whether the stringent protein in escherichia coli was lost from ribosomes at certain phase of growth as in other organisms (bacillus subtilis, mouse embryo), cells growing at various phases of the growth cycle were harvested and ribosomes tested for activity. the results showed that in e. coli, stringent protein was associated with the ribosomes throughout the growth cycle. the peak activity for the synthesis of guanosine tetra- and pentaphosphates appeared around midlogarithmic p ... | 1976 | 779841 |
| bacterial endotoxin and impaired fetal development. | small doses of e. coli endotoxin given to pregnant mice on the 13th day of pregnancy caused only a mild maternal illness but induced resorption of approximately half the number of fetuses in each mouse. the remaining live fetuses developed normally and showed no evidence of retarded growth or malformations. the weights of their placentas and maternal spleens increased significantly. endotoxin given on the 6th day of pregnancy caused a small reduction in fetal weights. | 1976 | 780127 |
| the structures and fidelity of replication of mouse mitochondrial dna-psc 101 ecori recombinant plasmids grown in e. coli k12. | recombinant dnas containing the e. coli plasmid psc101 and mouse cell (la9) mitochondrial dna (mtdna) were formed in vitro via ligation of dna fragments from limit ecori endonuclease digests and were used to transform e. coli k12. four structurally different recombinant plasmid dnas from transformed clones were characterized. two of these were analyzed extensively and the mtdna portions compared with mtdna from la9 cells. no differences were detected in the physical or chemical properties examin ... | 1976 | 782720 |
| antigenicity testing of inactivated oral enteric bacterial vaccines for human use. | this study deals with the laboratory testing of the antigenicity of inactivated oral enteric bacterial vaccines for human use, viz. typhoid, dysentery, escherichia coli and cholera vaccines. for the assays the following methods are applied : 1) various types of active mouse protection tests 2) serum and coproantibody determinations in immunized persons and experimental animals, 3) protective ability of the immune sera in mice and embryonated eggs, 4) hemolytic and bacteriolytic plaque assays. it ... | 1976 | 782974 |
| biological effects of escherichia coli lipopolysaccharide (lps) in vivo. ii. selection in the mouse thymus of pha- and con a-responsive cells. | the effect of lps injection on mouse thymocytes was examined by in vitro stimulation with pha and con a. thymocytes from lps treated mice were found more responsive than normal thymocytes to pha and con a. the increase of responsiveness was different for pha and con a, and dependent on the dose of lps injected. this dose dependency suggests that lps in vivo modifies the thymocyte population by progressively eliminating t1 cells and selecting t2 cells. these effects seem to be mediated by cortico ... | 1976 | 783042 |
| an in vitro immuno-enzymatic assay of tumor antigens in the mouse with beta-galactosidase. | a method for detection of the primary binding of soluble tumor-associated antigens by antibodies has been developed by using an enzyme immunoassay (eia). a heteroantiserum was produced by injecting tumor cells from a chemically induced murine sarcoma into rabbits, and antibodies reacting with most normal tissue components were removed by exhaustive in vivo absorption. a soluble preparation of tumor cells, obtained by 3 m kcl extraction, was conjugated to beta-galactosidase from escherichia coli. ... | 1976 | 784874 |
| etiologic diagnosis of diarrheal disease of calves: frequency and methods for detecting enterotoxin and k99 antigen production by escherichia cola. | escherichia coli isolated from calves in minnesota and montana were tested for enterotoxigenicity via bio-assay of cell-free broth culture fluid and for k99 antigen via a serum agglutination test. infant mice were used to assay for heat-stable enterotoxin (st), and adrenal cells in culture were used to assay for heat-labile enterotoxin (lt). forty-six of the 345 e coli isolates produced st enterotoxin, but none produced lt enterotoxin. thirty-five of the 46 enterotoxigenic isolates had k99 antig ... | 1976 | 786085 |
| separation of transfer ribonucleic acids on polystyrene anion exchangers. | the transfer rna separation by chromatography on strong-base polystyrene exchange materials is examined and compared with the widely used reversed-phase chromatography. results indicate important differences in some transfer rna (trna) elution patterns by the anion-exchange chromatography, as compared with the reversed-phase chromatography. transfer rnas containing hydrophobic groups are adsorbed more strongly. the anion exchanger has twice the number of theoretical plates. single peaks of trna2 ... | 1976 | 791362 |
| dual pathway of b lymphocyte differentiation in vitro. | direct visualization of the events resulting from lps stimulation of mouse spleen cells in vitro was achieved by characterizing the cells during four days of culture for morphology, ig and theta surface markers and autoradiography after [3h] thymidine uptake. the changes observed were related to biochemical parameters such as incorporation of [3h] thymidine into dna, ig biosynthesis and secretion. two pathways of b lymphocyte differentiation were observed: a) the generation of a large number of ... | 1976 | 791655 |
| genetic control of b cell activation by bacterial lipopolysaccharide is mediated by multiple distinct genes or alleles. | eleven closely related c3h mouse strains were examined for differences in their dna synthetic response to a highly discriminatory endotoxin, lps escherichia coli k-235. strains of the c3h line were found to be either high, intermediate, or low responders to endotoxin. three stains, c3h/st, c3h/bi, and c3h/cr were high responders. six strains, c3h/he, c3hfb/he, c3h/hen, c3heb/fej, c3h/disn, and c3h/avy were intermediate responders, suggesting that a mutation producing decreased lps responsiveness ... | 1976 | 792337 |
| characterization of the rna transcribed in vitro from native mammalian dna by escherichia coli rna polymerase. | high-molecular-weight native mouse dna was transcribed with escherichia coli rna polymerase under low salt conditions, and the nature of the dna sequences transcribed determined by molecular hybridization. the results indicated that e. coli rna polymerase does not transcribe the sequences in native mouse dna randomly under these conditions. first, hybridization with a large excess of mouse dna showed that no more than 5% of the rna synthesized had been transcribed from repeated sequences in the ... | 1976 | 793629 |
| excision-repair of 4-nitroquinolin-1-oxide damage responsible for killing, mutation, and cancer. | excision-repair of dna base damage produced by 4-nitroquinoline-1-oxide (4nqo) was compared in escherichia coli, human cells, and mouse cells. paper chromotography of acid hydrolysates of dna extracted from cells treated with 3h-labeled 4nqo revealed four peaks; two kinds of 4nqo-guanine adduct, one kind of 4nqo-adenine adduct, and free 4-aminoquinoline-1-oxide (4aqo). about 80% of the initially formed 4nqo-purine adducts were excised from dna in e. coli uvra+ cells during 60 min postincubation, ... | 1975 | 811213 |
| immune responses of specific pathogen-free and gnotobiotic mice to antigens of indigenous and nonindigenous microorganisms. | strains of indigenous escherichia coli, bacteroides, and lactobacillus were isolated from the gastrointestinal tracts of specific pathogen-free (spf) mice. nonvaccinated spf mice exhibited in their spleens low numbers of plaque-forming cells (pfc) and rosette-forming cells reacting with antigens of these andigenous bacteria. pfc reacting with these bacterial antigens were not detected in infant spf mice until 7 days after birth. compared with nonvaccinated controls, spf mice vaccinated parentera ... | 1975 | 1089600 |
| receptor sites for antigen-antibody complexes on cells derived from solid tumors: detection by means of antibody sensitized sheep erythrocytes labeled with technetium-99m. | surface receptor sites for the fc portion of antigen-antibody complexes were demonstrated on cells derived from three methylcholanthrene-induced fibrosarcomas, one of strain c3h and two of strain balb/c origin, two spontaneously occurring malignant melanomas (b16 in strain c57bl/6 and harding-passey in strain balb/c mice), a moloney sarcoma virus-induced tumor of strain balb/c origin and the walker 256 carcinosarcoma of holtzman rats. primary cell cultures derived from these tumors adsorbed tech ... | 1975 | 1089728 |
| effect of exposure to hyperoxic, hypobaric, and hyperbaric environments on concentrations of selected and aerobic and anaerobic fecal flora of mice. | alterations in selected aerobic and anaerobic fecal microflora of the mouse were determined during exposure to hyperoxic and normoxic hypo- and hyperbaric environments. examination of fecal cultures obtained during exposure for 6 weeks to either 60 or 77% oxygen concentration 1 atmosphere absolute revealed little alteration in the aerobic or anaerobic flora. there appeared to be only a retardation in the reduction of the klebsiella-enterobacter flora which normally occurs after weaning. during e ... | 1975 | 1090255 |
| comparative mitogenic responses of t-cells and b-cells in spleens of mice of varying age. | mouse spleen cell mitogenic responses to phytohemagglutinin (pha), conconavalin a (con a), staphylococcal enterotoxin b (seb) and lipopolysaccharide (lps) were studied as a function of age. in cd-1 mice, spleen cell dna synthesis in response to stimulation by pha, con a and seb varied from 18% - 33% of adult values for the first 3 weeks of life. by 6 weeks, the pha response was 63% of the adult response and achieved adult values by 8 weeks of life. in contrast to these t-cell responses, dna sple ... | 1975 | 1090516 |
| effects of concanavalin a on the in vitro responses of mouse spleen cells to t-dependent and t-independent antigens. | ?the stimulatory and inhibitory effects of concanavalin a (con a) on the in vitro primary immune responses to a t-dependent antigen, sheep erythrocytes (srbc) and a t-independent antigen, tnp-lipopolysaccharide (tnp-lps) have been studied. inhibition of the response to both antigens was optimal when 2 mug con a were added at the initiation of the culture period. the response to srbc was considerably enhanced by the addition of con a 24 hr later. in contrast, this late addition did not stimulate ... | 1975 | 1090654 |
| effect of acinetobacter glutaminase-asparaginase treatment on free amino acids in mouse tissues. | acinetobacter glutaminase-asparaginase (aga) and escherichia coli asparaginase were compared for their effects on plasma and tissue levels of amino acids, ammonia, and glutamyl transferase activity in the mouse. free asparagine was depleted similarly in plasma and tissues by both enzymes. aga treatment produced partial depletion of glutamine concentrations in muscle, spleen, small intestine, and liver. brain and kidney glutamine concentrations actually rose with treatment. despite over 100-fold ... | 1975 | 1091350 |
| the primary structure of the major cytoplasmic valine trna of mouse myeloma cells. | this paper describes the derivation of the primary structure of the major valine trna in the cytoplasm of mouse myeloma cells. approximately 75% of the nucleotide sequence of this trna is also shared by the trna1-val of yeast, this homology serving as a further indication of the extreme conservation of the structures of the trnas of different eukaryotic organisms. a novel feature of mouse myeloma trna1-val is its loop iv sequence: -u-psi-c-g-m1a-a-a-. this particular loop iv sequence has not pre ... | 1975 | 1091487 |
| functional heterogeneity among the t-derived lymphocytes of the mouse. iii. helper and suppressor t-cells activated by concanavalin a. | | 1975 | 1095214 |
| inhibition of thymidylate synthetase and dihydrofolate reductase by naturally occurring oligoglutamate derivatives of folic acid. | naturally occurring oligoglutamate derivatives of folic acid in extracts of escherichia coli have been isolated on the basis of their inhibitory actions toward thymidylate synthetase and dihydrofolate reductase. the inhibitor of thymidylate synthetase has been identified as n-5-formyl-h4pteroyloligoglutamate (approximately 5 amino acid residues). it is 150-fold more inhibitory than the monoglutamate. synthetic n-5-formyl derivatives containing 3 to 6 glutamyl residues were prepared and found to ... | 1975 | 1095583 |
| isolation and partial characterisation of the relaxation protein from nuclei of cultured mouse and human cells. | a protein, called relaxation protein because of its ability to remove superhelical turns in closed-circular dna, has been isolated and partially characterized from the nuclei of la9 mouse and hela cells. the purification was facilitated by an assay method, with pm2 dna, which used the fluorescence enhancement of the intercalating dye ethidium bromide upon binding to the closed-circular dna. the amount of dye bound depends upon the degree of the superhelix density of the dna. the relaxation produ ... | 1975 | 1100383 |
| studies of mouse mitochondrial dna in escherichia coli: structure and function of the eucaryotic-procaryotic chimeric plasmids. | the mouse mitochondrial dna genome has been cloned in escherichia coli by linking it to the psc101 plasmid replicon at cohesive-ended cleavage sites generated by eco rl restriction endonuclease. the four possible configurations of chimeric molecules that contain the nucleotide sequences of mitochondrial dna in their native relationship were distinguished by hind iii restriction endonuclease digestion and electron microscopic heteroduplex analysis. chimeric molecules utilize the psc101 replicatio ... | 1975 | 1102112 |
| inflammatory mediators in culture filtrates of escherichia coli. | escherichia coli, when cultured on a simple medium containing only glucose and inorganic compounds, release soluble factors which have a variety of biologic effects on cells in vitro. these low molecular weight (less than 12,000) substances are capable of: a) reversibly inhibiting the migration of macrophages, b) causing chemotactic attraction of neutrophils, c) inducing blast transformation of lymphocytes, and d) producing cytotoxic effects on mouse fibroblasts in culture. although these activi ... | 1975 | 1103632 |
| experimental amyloidosis: the inducer is a polyclonal b-cell activator to which susceptibility is under genetic control. | experimental amyloidosis in mice can be induced by repeated injections of casein. it has now been demonstrated that casein induces strong polyclonal antibody synthesis in mouse b spleen lymphocytes. this effect is much more pronounced in spleen cells from anyloid-susceptible mice (cba/j) than amyloid-resistant mice (a/j). it is suggested that amyloidosis can be due in some instances to a constant exposure for molecules which induce polyclonal b-cell activation. | 1975 | 1104749 |
| blastogenesis of human lymphocytes by endotoxin. | lipopolysaccharides of s. typhimurium, s. enteritidis and e. coli at wide range of concentrations were used to induce blastogenesis in human and mouse (nude) lymphocytes. human lymphocytes from peripheral blood showed positive response to at least one source of lps (stimulation index of 2-9). the optimum concentration resulting in maximum stimulation varied with different individual, sources and concentrations of lps used. lymphocytes from cord blood failed to respond to lps, but had positive re ... | 1975 | 1107213 |
| modification of resistance of mice to naegleria fowleri infections. | naegleria fowleri, which produces a fatal meningoencephalitis in humans, is also able to produce a progressive and fatal disease in mice. the course of the disease in dub/icr mice is dependent upon the infecting dose of organisms, whether administered intraperitoneally (i.p.) or intravenously (i.v.). all of the mice receiving 10(7) trophozoites/mouse i.v. or 4.85 x 10(7) trophozoites/mouse i.p. were killed within 10 days. escherichia coli o26:b6 lipopolysaccharide, administered at a dose of 1 mg ... | 1976 | 1270145 |
| t and b cell epitope mapping of sm23, an integral membrane protein of schistosoma mansoni. | sm23 is an integral membrane protein of the blood-vessel dwelling parasitic worm schistosoma mansoni. this protein has been detected with antibodies in all stages of the parasite found in the human host, notably the lung stage, and therefore is of interest as a vaccine candidate. in addition sm23 has been shown to be a member of a proposed new superfamily of membrane proteins whose structures do not conform to the previously known classifications. to date there are 13 members including me491 (cd ... | 1992 | 1281197 |
| cloning of the vaccinia virus ribonucleotide reductase small subunit gene. characterization of the gene product expressed in escherichia coli. | during its infectious cycle, vaccinia virus expresses a virus-encoded ribonucleotide reductase which is distinct from the host cellular enzyme (slabaugh, m.b., and mathews, c.k. (1984) j. virol. 52, 501-506; slabaugh, m.b., johnson, t.l., and mathews, c.k. (1984) j. virol. 52, 507-514). we have cloned the gene for the small subunit of vaccinia virus ribonucleotide reductase (designated vvr2) into escherichia coli and expressed the protein using a t7 rna polymerase plasmid expression system. afte ... | 1992 | 1309792 |
| regulation of the escherichia coli lac operon expressed in human cells. | we have investigated the use of various epstein-barr virus (ebv)-based vectors bearing the two components of the escherichia coli lac operator-repressor (laco, laci) complex. our aim was to develop a model system of gene expression by looking at the transcription of the bacterial beta-galactosidase coding gene (lacz) in 293 human embryonic kidney cells. several vectors have been built carrying different promoters upstream of the laci and lacz genes and in which natural or synthetic operator sequ ... | 1992 | 1311956 |