Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| cloning of mouse beta-casein gene sequences. | casein messenger rnas (mrnacsn) were purified from lactating mammary glands of balb/c mice and used as a starting material for cloning of casein gene sequences. double-stranded casein cdna (ds-cdnacsn) was prepared and blunt-end ligated to hindiii-specific dna linker molecules. after digestion with hindiii, the dsdnacsn was inserted into the hindiii site of plasmid pbr322, using t4 dna ligase. escherichia coli strain rh202 was transformed with the hybrid plasmids, and transformants were selected ... | 1981 | 7297856 |
| intranuclear incorporation of thymic low molecular weight rna by murine bone marrow immunoblasts and inhibition of plasma cell formation by a derivative of rifampicin. | an in vitro culture system for the proliferation of igg-forming plasma cells from mouse bone marrow cultures has previously been described. the present study attempts to elucidate the mode of action of thymic rna in these cultures. autoradiography after using radiolabeled thymic rna showed that radioactive material was mainly incorporated into the nuclei of igg-forming plasma cells. no radiolabeled thymic rna was incorporated into the cells except immunoblasts. the incorporated thymic rna was ac ... | 1982 | 6178004 |
| mechanism of interferon action. kinetics of induction of the antiviral state and protein phosphorylation in mouse fibroblasts treated with natural and cloned interferons. | the induction of phosphorylation of both protein p1 and protein synthesis initiation factor eif-2 alpha and the inhibition of virus replication were examined in mouse l929 fibroblasts treated with either natural mouse or individual cloned human interferons (ifn). natural mouse ifn synthesized in newcastle disease virus-induced l929 cells and two cloned human leukocyte ifn subspecies synthesized in escherichia coli, ifn-alpha d and ifn-alpha a/d, possessed antiviral activity in l929 cells as meas ... | 1982 | 6181059 |
| mouse interferons enhance the accumulation of a human hla rna and protein in transfected mouse and hamster cells. | a recombinant clone (pjy150r1.1) encoding the human major histocompatibility antigen (hla-b7) was introduced into mouse cells and hamster cells by cotransformation with selectable genes. the exposure to mouse interferon of the cells transformed to hla-b7+ resulted in a severalfold increase in the level of hla antigen and rna. the hla-b7 clone used for the transfection includes a 670-base pair dna sequence upstream from the coding segment. it remains to be established if the 670-base pair segment ... | 1982 | 6183260 |
| biosynthesis of preprorenin. studies using whole tissue, a cell-free system, and e. coli containing cdna inserted at the psti site of plasmid pbr322. | the biosynthesis of renin as a higher molecular weight 'prorenin' was demonstrated by in vitro incorporation of [35s] methionine into nascent polypeptides of submandibular gland tissue from adult male mice. immunoprecipitation with anti-renin and electrophoresis identified a mr 44,500, pi 6.4 prorenin which normally represented 5% of renin-immunoreactive protein in tissue extracts and which was rapidly converted during in vitro labeling into a mr 40,000, pi 6.2 species. the latter was subsequent ... | 1982 | 6184188 |
| computer analysis of the sequence relationships among 4.5s rna molecular species from various sources. | nucleotide sequence homology among 4.5s rnas from various organisms was examined by computer analysis to evaluate their sequence relationships. chloroplast 4.5s rrnas of wheat and tobacco were not significantly related to escherichia coli 4.5s rna, but were closely related to the 3'-terminus of bacterial 23s rrna. significant sequence homology was found between rat novikoff hepatoma 4.5s rnai and mouse and hamster 4.5s rnas, suggesting that these rnas are products of a family of genes with diver ... | 1982 | 6184365 |
| characterization of the free radical of mammalian ribonucleotide reductase. | mouse fibroblast 3t6 cells, selected for resistance to hydroxyurea, were shown to overproduce protein m2, one of the two nonidentical subunits of mammalian ribonucleotide reductase. packed resistant cells gave an epr signal at 77 k very much resembling the signal given by the tyrosine-free radical of the b2 subunit of escherichia coli ribonucleotide reductase. also, the m2-specific free radical was shown to be located at a tyrosine residue. of the known tyrosine-free radicals of ribonucleotide r ... | 1982 | 6279610 |
| efficient expression of escherichia coli galactokinase gene in mammalian cells. | the escherichia coli galactokinase gene (galk) was inserted into a modified early region transcription unit of simian virus 40 (sv40) contained on a bacterial plasmid. introduction of this psvk vector into monkey, mouse, and hamster cell lines by transfection resulted in efficient expression of the bacterial galk gene. this expression was shown to be dependent upon fusion of the galk gene to the early promoter of sv40 and did not appear to require sv40 splice signals. moreover, expression in the ... | 1982 | 6281760 |
| specific molecular activities of recombinant and hybrid leukocyte interferons. | hybrid interferon dna recombinants were constructed from the iflra and iflrd leukocyte interferon-coding sequences. each of the hybrid interferons was purified with the use of a monoclonal antibody to human leukocyte interferon. three amino acid residues were identified, one or all of which function to potentiate antiviral activity on feline cells and reduce activity on human cells. because at sufficiently high concentrations human interferons can interact with mouse and rat receptors, it is app ... | 1982 | 6288687 |
| effect of murine beta-interferon preparation on phagocytosis and cyclic amp levels in mouse peritoneal macrophages. | mouse peritoneal macrophages (mpm) cultivated with a mouse beta-interferon preparation (muifn-beta) or "mock" ifn were tested for phagocytic ability and intracellular levels of adenosine 3',5'-cyclic monophosphate (camp). suspensions of nonopsonized escherichia coli (e. coli) were used for phagocytosis experiments. treatment of mpm with 10(1)-10(3) u per ml of muifn-beta stimulated the phagocytic activity and raised the levels of camp in mpm. the effect of muifn-beta on camp levels were dose and ... | 1982 | 6288813 |
| a comparison of nucleoside (beta-s)triphosphates and nucleoside (gamma-s)triphosphates as suitable substrates for measuring transcription initiation in preparations of cell nuclei. | rna chains initiated with nucleoside (beta-s)triphosphates and (gamma-s)triphosphates retain the thiol groups and can be separated from thiol-free rna by chromatography on mercury-sepharose. thiol-containing mouse mammary tumor virus (mmtv) rna synthesized by preparations of nuclei from virus-infected cells was quantitated by nucleic acid filter hybridization. with atp beta s and gtp beta s, region-specific initiation of mmtv rna chains was detected in the cell free system. however, with atp gam ... | 1982 | 6298716 |
| chemical and biological properties of lipopolysaccharide from a marine bacterium, photobacterium phosphoreum pj-1. | the chemical and biological properties of the lipopolysaccharide (lps) isolated from a marine bacterium, photobacterium phosphoreum pj-1, were studied. this lps consists of 40.6% carbohydrate, 27.3% fatty acid, 0.2% 2-keto-3-deoxyoctonate (kdo) and other components. one characteristic of this lps is its small amount of kdo, the basic component of the usual lps. electrophoresis in sodium dodecylsulfate polyacrylamide gel revealed at least two staining bands for carbohydrates. these bands were con ... | 1982 | 6752664 |
| microbial mutation studies with tetrachlorvinphos (gardona)). | the mutagenic activity of tetrachlorvinphos was investigated in agar-layer cultures of escherichia coli wp2 and wp2 uvra, salmonella typhimurium ta1535, ta1538, ta98 and ta100. assays were carried out both in the presence and in the absence of s9 fractions of liver homogenates from rats and mice, both from untreated animals, and from animals pre-treated with aroclor 1254. the induction of mitotic gene conversion by tetrachlorvinphos was studied in stationary phase cultures of the yeast saccharom ... | 1982 | 6752704 |
| renin synthesis and gene cloning. | 1. the present study describes the biosynthesis and gene cloning of mouse submandibular gland renin. 2. after translation of mrna coding for renin a mr 46 000 protein is produced (preprorenin). however, rapid removal of the 'pre' segment from the nascent chain would account for the fact that in pulse-chase and continuous labelling experiments the largest renin-immunoreactive protein seen was of mr 44 500, pi 6.4 (determined by 2-dimensional gel electrophoresis). this 'prorenin' was rapidly conve ... | 1982 | 6754188 |
| failure to detect conventional enterotoxins in classical enteropathogenic (serotyped) escherichia coli strains of proven pathogenicity. | ammonium sulfate-precipitated supernatants of classical enteropathogenic escherichia coli strains were negative when investigated for enterotoxin production in rabbit ligated ileal loops, rabbit skin vascular permeability factor tests, suckling mice, and y-1 adrenal cells. they also failed to stimulate guanylate cyclase activity in homogenates of rabbit, rat, and infant mouse intestines. furthermore, dna from enteropathogenic e. coli lacked sequences that encode heat-labile and heat-stable enter ... | 1982 | 6754624 |
| inhibition of calf thymus dna polymerase alpha and of normal and cancer cell growth by butylanilinouracil and butylphenylguanine. | 6-(p-n-butylanilino)uracil and n2-(p-butylphenyl)guanine inhibited the activity of dna polymerase alpha from calf thymus but had no effect on other eukaryotic polymerases (dna polymerases beta and gamma) or escherichia coli dna polymerase i. inhibition was competitive with deoxyguanosine 5'-triphosphate and did not occur in the reaction of dna polymerase alpha with a template that did not contain cytosine residues. the results support a mechanism which involves hydrogen bonding of inhibitors wit ... | 1982 | 6756479 |
| relative colonizing abilities of human fecal and k 12 strains of escherichia coli in the large intestines of streptomycin-treated mice. | male cd-1 mice, fed streptomycin in their drinking water, were used to study colonization of the mouse intestine by both fecal escherichia coli strains isolated from healthy humans and escherichia coli k12 strains which are routinely used as hosts for recombinant dna. prior to use in mice, all the strains were made resistant to streptomycin. several facts emerged from these studies: (a) strains isolated from different healthy humans colonized the mouse intestine with equal ability (approximately ... | 1982 | 6756909 |
| failure of bacterial lipopolysaccharide to elicit a cytostatic effect on plasmodium vinckei petteri in c3h/hej mice. | malarial parasites, plasmodium vinckei petteri, taken from lipopolysaccharide (lps) high-responder (c3h/hejgifwehi) mice which had been injected 7 to 8 h previously with either escherichia coli lps b or lps w incorporated the purine nucleotide precursor hypoxanthine more slowly in an in vitro assay than parasites taken from saline-injected controls. in contrast, malarial parasites taken from lps low-responder c3h/hej mice after injection of either lps b or lps w did not show reduced levels of hy ... | 1982 | 7033142 |
| identification of enterotoxigenic escherichia coli by colony hybridization using three enterotoxin gene probes. | the applicability of examining clinical specimens with a dna hybridization technique for genes encoding enterotoxins was examined using enterotoxigenic escherichia coli (etec) that produced both heat-labile toxin (lt) and heat-stable toxin (st) (24 isolates), etec that produced lt only (17 isolates), and etec that produced st only (22 isolates) from thailand. etec was identified with y-l adrenal cell and suckling mouse assays. all were homologous with radiolabeled fragments of dna encoding lt or ... | 1982 | 7045250 |
| de novo dna synthesis by a novel mouse dna polymerase associated with primase activity. | 1982 | 7045691 | |
| release of endotoxic lipopolysaccharide by sensitive strains of escherichia coli submitted to the bactericidal action of human serum. | free endotoxin was assayed in filtered samples of e. coli suspensions submitted to the bactericidal and bacteriolytic action of 10% human serum. the limulus amoebocyte lysate test, a passive hemolysis inhibition assay based on o antigenic specificity and the determination of 3-oh-myristic acid by mass spectrometry were used as assay methods differing from one another with regard to the part of the endotoxin macromolecule involved in the reaction. the biological activity of endotoxin was assessed ... | 1982 | 7048047 |
| chemical modifications of escherichia coli l-asparaginase and their effect on plasma clearance rate and other properties. | escherichia coli asparaginase (l-asparagine amidohydrolase, ec 3.5.1.1) has been modified by succinylation, acetylation and the attachment of n,n-dimethyl-1,3-propanediamine and glucuronic acid. the effect of these modifications on plasma clearance rates in mice and on other properties is compared to the effects of modification with lactose and n-acetylneuraminyl lactose studied previously. the t 1/2 values for the acylated enzyme samples (lower pi) were reduced, succinylated asparaginase sharpl ... | 1982 | 7049249 |
| morphologic and functional effects of clostridium difficile enterotoxin in tissue culture. | the effects of the clostridium difficile toxin were examined in hela and mouse adrenal tumor (mat) cells. cytotoxicity was evaluated by vital dye exclusion and 51cr release. in both hela and mat cells, c. difficile toxin caused rounding of virtually 100% of cells. this rounding was distinguishable from rounding produced by the escherichia coli heat-labile enterotoxin (lt): (1) lt was inactive in hela cells; (2) in mat cells, c. difficile toxin produced uniformly rounded cells, while lt-rounded c ... | 1982 | 7066760 |
| methods for the detection of single-strand breaks in dna under neutral conditions and their application in a study on the mechanism of repair of n-methylated purines in mouse cells. | considering enzymatic activities found in bacteria and in animal cells, there are two possible mechanisms for repair of n-methylated purines produced by methylating agents such as the mutagen and carcinogen n-methyl-n'-nitro-n-nitrosoguanidine. both mechanisms involve first an enzymatic removal of the methylated bases by glycosylases. the resulting apurinic sites could then be repaired by (a) direct insertion of the correct bases purine insertases or (b) opening of the polynucleotide chain by ap ... | 1982 | 7106118 |
| antibodies to ornithine decarboxylase. immunochemical cross-reactivity. | l-ornithine decarboxylase was purified to apparent homogeneity from the kidneys of testosterone-treated mice. antibodies to ornithine decarboxylase were raised in a rabbit using the purified enzyme. ouchterlony double diffusion technique revealed a single precipitin line between the antiserum and purified mouse kidney ornithine decarboxylase. the antibodies inhibited ornithine decarboxylase from various tissues of mice and rats to the same extent, indicating a close immunological relationship. s ... | 1982 | 7164704 |
| the role of interleukin 1 in acute phase serum amyloid a (saa) and serum amyloid p (sap) biosynthesis. | the acute phase saa and sap profiles have been compared for localized and endotoxin induced inflammation in lps responder and nonresponder strains of mice. the sap profile can reflect a delay with respect to the start of the increase. its maximum is on the order of ten times the nonacute phase concentration and elevated concentrations are sustained 24 to 48 hours after saa concentration is rapidly decreasing to normal. the role of interleukin 1, known to have an essential role in saa production, ... | 1982 | 6807177 |
| synthesis by the dna primase of drosophila melanogaster of a primer with a unique chain length. | the primase associated with the dna polymerase alpha from embryos of drosophila melanogaster catalyzes the synthesis of ribo-oligonucleotide primers on single-stranded m13 dna or polydeoxythymidylate templates, which can be elongated by dna polymerase action [conaway, r. c. & lehman, i. r. (1982) proc, natl. acad. sci, usa 79, 2523--2527]. the primers synthesized in a coupled primase-dna polymerase alpha reaction with an m13 dna template are of a unique size (15 residues); those synthesized with ... | 1982 | 6812052 |
| lipopolysaccharide-induced activation of suppressor cells: reversal by an agent which alters cyclic nucleotide metabolism. | the effects of bacterial lipopolysaccharides (lps) on the suppressor activity of mouse spleen cells were examined. pretreatment with lps was shown to induce suppressor activity in vivo and in vitro. concurrent treatment of spleen cells with lps and imidazole, an agent which increases the activity of cyclic nucleotide phosphodiesterases and hastens the degradation of cyclic amp, reversed the suppressor-inducing effects of lps. in vitro treatment of spleen cells with aminophylline, an agent which ... | 1982 | 6459992 |
| virulence of escherichia coli in ascending urinary-tract infection in mice. | the virulence of escherichia coli strains in ascending urinary-tract infection was studied in mice drinking a 5% glucose solution; factors determining the virulence were examined. of 33 strains, 8 (group i) infected the bladder and kidney, 10 (group ii) infected only the bladder, while the remaining 15 strains (group iii) did not cause infection. the adherence of group-i and group-ii strains to bladder epithelial cells in vitro was inhibited by d-mannose. in group iii, 13 strains barely adhered ... | 1982 | 6126593 |
| genotoxicity of nitrosated ranitidine. | the in vitro reaction of nitrite with the histamine h2-receptor antagonist ranitidine, in acidified solutions or in human gastric juice, resulted in the formation of genotoxic derivatives, mainly eliciting base-pair substitutions in his-salmonella typhimurium and trp- escherichia coli and inducing an increased lethality in dna repair-deficient bacteria. the mutagenic response was better expressed in the presence of rodent (rat, mouse) and even more of human liver preparations. the patterns of th ... | 1983 | 6131752 |
| monoclonal antibodies against colonization factor antigen i pili from enterotoxigenic escherichia coli. | hybridomas secreting monoclonal antibodies directed against intact colonization factor antigen i pili have been produced by the fusion of spleen cells from immunized balb/c mice with ns1/sp2 myeloma cells. the four monoclones with the highest antibody titer, as detected by enzyme-linked immunosorbant assay (elisa), were chosen for antibody amplification by production of mouse ascitic fluid. these four were examined for antibody specificity by elisa and immunoblot assays, using six different pilu ... | 1983 | 6136463 |
| urinary tract infectivity or r strains of escherichia coli carrying various virulence factors. | the virulence factors of escherichia coli supposed to act in urinary tract infections were studied on r strains in a suckling mouse model. the production of alpha-(diffusible-) haemolysin or the possession of antigen k1 enhanced the virulence significantly, while the type 1 (common) fimbriae failed to do so. an isogenic motile and non-motile pair of e. coli did not show any difference in infectivity in the model. the adhesins, the diffusible haemolysin, and the acidic polysaccharide k antigens ( ... | 1983 | 6140809 |
| novel fluorinated antifolates. enzyme inhibition and cytotoxicity studies on 2'- and 3'-fluoroaminopterin. | two novel analogues of aminopterin with a single fluorine substitution in the 2' (compound 8) or in the 3' (compound 9) position of the p-aminobenzoyl group were synthesized and evaluated as inhibitors of dihydrofolate reductase from two bacterial species and from human hela cells. the 2'-fluoro compound was bound essentially the same as aminopterin itself, while the 3'-fluoro derivative bound two- to threefold more tightly in all cases. uv spectral shifts indicated normal binding of the pteridi ... | 1983 | 6410066 |
| cloned mouse interferon-gamma inhibits the growth of rickettsia prowazekii in cultured mouse fibroblasts. | the effect of treating cultured mouse fibroblasts (l929 cells) with cloned mouse interferon-gamma on the growth of rickettsia prowazekii within the fibroblasts was studied. within 48 h after infection, rickettsiae were cleared from a substantial proportion of the initially infected cells and rickettsial growth was inhibited in those cells that remained infected, when l929 cells were treated with cloned mouse interferon-gamma both before and after infection. when l929 cells were treated with clon ... | 1983 | 6417262 |
| isolation and characterization of monoclonal antibodies directed against the dna repair enzyme uracil dna glycosylase from human placenta. | a series of monoclonal antibodies has been prepared against the base excision repair enzyme uracil dna glycosylase isolated from human placenta. spleen cells from balb/c mice immunized with purified human placental uracil dna glycosylase were fused with either p3x63 ag8.653 or sp2/0 myeloma cells. hybridomas producing antibodies directed against the placental glycosylase were identified in an enzyme-linked immunosorbent assay. each positive hybridoma was cloned twice by limit dilution and tested ... | 1983 | 6577457 |
| induction of histidine decarboxylase in mouse tissues by mitogens in vivo. | various types of mitogenic substances, such as a escherichia coli lipopolysaccharide (lps), concanavalin a (con a), pokeweed mitogen, polyi:polyc (a synthetic double-stranded rna) and 12-o-tetradecanoylphorbol-13-acetate (a component of croton oil), induced histidine decarboxylase (hdc) in the liver, spleen and lung of mice at 4.5 hr after injection. other inflammatory agents without mitogenic activity, such as zymosan, carrageenan, glycogen, d-galactosamine and n-acetyl-muramyl-l-alanyl-d-isogl ... | 1983 | 6661256 |
| toxin a of clostridium difficile: production, purification and effect in mouse intestine. | clostridium difficile produces one diarrhoeogenic toxin designed a, and one cytopathogenic toxin designed b. toxin a was purified in a four-step-fractionation procedure. in the last purification step the toxin was separated by elution with galactose from an agarose gel. the purified toxin a induced a clear and watery hypersecretion in intestinal loops of mouse, while mixtures of toxin a and b induced a haemorrhagic secretion. at an ed50 value for the purified toxin a of 0.5 microgram there was a ... | 1983 | 6673499 |
| chemical and immunological properties of escherichia coli heat-stable enterotoxin. | five heat-stable enterotoxins (sts) produced by enterotoxigenic e. coli (etec) strains of porcine, bovine and human origin have been purified to apparent homogeneity. the sts with biological activity in suckling mice and piglets (sta) contained 18 amino acid residues, 10 or 11 different amino acids with a high proportion of acidic amino acids and 6 half-cystines. all 5 purified preparations were heat-stable, not denatured by organic solvents and detergents, resisted protease digestion and treatm ... | 1983 | 6686335 |
| escherichia coli heat-stable enterotoxin: biochemical and physiological effects on the intestine. | e. coli which elaborate suckling mouse active small mw heat-stable enterotoxin (sta), are important causes of diarrhea in animals and man. these sta's share the property of causing intestinal secretion and diarrhea by virtue of inhibiting the absorption of sodium and chloride and possibly stimulating the secretion of chloride. sta's seem to act in the colon as well as the small intestine and the alterations in intestinal ion and water transport are probably mediated by the guanylate cyclase-cycl ... | 1983 | 6686336 |
| isolation of recombinant bacteriophage containing male-specific mouse dna. | the mammalian y chromosome is an isolated piece of genetic material that directs sexual determination and gametogenesis. very little is understood about the mechanism whereby the y chromosome carries out these functions. also, there is a severe lack of genetic markers on this chromosome. in order to understand the structure and function of the y chromosome at the level of its dna sequences and to provide genetic markers, we are isolating clones of dna whose sequences are found primarily in dna f ... | 1983 | 6222247 |
| infant mouse model of e. coli diarrhoea: clinical protection induced by vaccination of the mothers. | protection of infant mice against experimental e. coli b41 diarrhoea by immunization of the mothers with homologous e. coli strain was studied. the influence of the number, dose, route and moment of vaccination(s) on protection, measured by the reduced mortality rate of infant mice during the 15 days following oral challenge, was tested. the highest dose of vaccine, namely 10(8) formalin-killed e. coli by parenteral routes or 3 x 10(9) live e. coli by peroral (p.o.) route resulted in the best ef ... | 1983 | 6362544 |
| [therapeutic effects of micronomicin on experimental infections in mice by intravenous administration]. | protective effects of intravenous administration of micronomicin (mcr) on mouse experimental infections were investigated. mice were better protected by intravenous administration in s. marcescens t-55 experimental infection than subcutaneous administration. no remarkable differences were found between the two administrations in cases of p. aeruginosa bmh no. 1 and e. coli gn 2411-5 infections. intravenous administrations of mcr, gentamicin (gm), dibekacin (dkb), amikacin (amk) and sisomicin (si ... | 1983 | 6371292 |
| [effect of orally administered bovine lactoferrin and bovine igg on the establishment of escherichia coli in the digestive tract of gnotobiotic mice and human newborn infants]. | the bacteriostatic effect of the association bovine lactoferrin (lf) and bovine igg (igg) was studied in vitro and in vivo against two escherichia coli strains, s17 and emo1, isolated from the faecal flora of mouse and man, respectively. these two strains were sensitive in vitro to the bacteriostatic effect of lf + igg. a kinetic study of the in vivo establishment of e. coli s17 was followed in axenic mice associated with that strain. seven hours after inoculation, no difference was observed in ... | 1983 | 6372577 |
| recovery of a hybrid vector, derived from bovine papilloma virus dna, pbr322 and the hsv tk gene, by bacterial transformation with extrachromosomal dna from transfected rodent cells. | a bovine papilloma virus (bpv)-pbr322-derived recombinant plasmid carrying a 2-kb fragment of herpes simplex virus dna containing the thymidine kinase (tk) gene is capable of transforming tk- cells of mouse l and syrian hamster bhk21 lines to tk+. in transformed cells a small proportion of the plasmid dna is present as extrachromosomal elements while the remainder appears to be integrated into the genome. it was possible to recover plasmids indistinguishable from the input dna by transformation ... | 1983 | 6303907 |
| isolation and characterization of genomic mouse dna clones containing sequences homologous to trnas and 5s rrna. | we have cloned and characterized three fragments of balb/c mouse dna which hybridize to mouse cell trnas. fractionation of the trnas which hybridize to these clones reveals that two of the clones, lambda mt-4a and lambda mt-6a hybridize to only one or two trnas, while one clone, lambda mt-4b, hybridizes to at least seven trnas. two of the trnas were identified as trnaproccg and trnaglygga, and others have been identified as trnas which are selectively encapsidated into virions of murine leukemia ... | 1983 | 6308561 |
| detection and mapping of homologous, repeated and amplified dna sequences by dna renaturation in agarose gels. | a new molecular hybridization approach to the analysis of complex genomes has been developed. tracer and driver dnas were digested with the same restriction enzyme(s), and tracer dna was labeled with 32p using t4 dna polymerase. tracer dna was mixed with an excess amount of driver, and the mixture was electrophoresed in an agarose gel. following electrophoresis, dna was alkali-denatured in situ and allowed to reanneal in the gel, so that tracer dna fragments could hybridize to the driver only wh ... | 1983 | 6310499 |
| intra-abdominal abscess formation in mice: quantitative studies on bacteria and abscess-potentiating agents. | a model of intra-abdominal (ia) abscess formation has been developed in mice. intraperitoneal (i.p.) injection of a mixture of a potentiating agent (autoclaved colonic and caecal contents (acc), 0.2 mg dry wt/mouse or sterile bran, 1 mg dry wt/mouse), escherichia coli (1 x 10(6) colony forming units (cfu)/mouse) and bacteroides fragilis (5 x 10(8) cfu/mouse) induced abscesses in 98% of mice inoculated. the abscesses persisted for at least 4 weeks in 60% of inoculated animals, and for 10 weeks in ... | 1983 | 6311236 |
| properties of synthetically produced escherichia coli heat-stable enterotoxin. | the properties of a synthetically produced peptide composed of the same primary structure of 18 amino acids described for human escherichia coli heat-stable enterotoxin were compared with those of purified heat-stable toxin obtained by bacterial growth. the dosage required to evoke fluid secretion in the suckling mouse and rat ligated ileal loop assays was the same for both toxins. the antigenicity of the two toxins was similar when assayed by enzyme-linked immunosorbent assay with hyperimmune a ... | 1983 | 6337093 |
| experimental and mathematical models of escherichia coli plasmid transfer in vitro and in vivo. | little is known about the factors that govern plasmid transfers in natural ecosystems such as the gut. the consistent finding by earlier workers that plasmid transfer in the normal gut can be detected only at very low rates, if at all, has given rise to numerous speculations concerning the presence in vivo of various inhibitors of plasmid transfer. plasmids r1, r1drd-19, and pbr322 were studied in escherichia coli k-12 and wild-type e. coli hosts in two experimental systems: (i) gnotobiotic mice ... | 1983 | 6337105 |
| cellular uptake and inhibition of dna synthesis by dihydroxyanthraquinone and two analogues. | three analogues of aminoalkylamino-substituted anthraquinone derivatives, namely, 1,4-dihydroxy-5,8-bis(((2-[(2-hydroxyethyl)amino]ethyl)amino))-9,10-anthracenedione (dhaq), 1-hydroxy-5,8-bis(((2-[(2-hydroxyethyl)amino]ethyl)amino))-9,10-anthracenedione (haq), and 1,4-bis(((2-[(2-hydroxyethyl)amino]ethyl)amino))-9,10-anthracenedione (aq), were chosen with respect to the number of hydroxyl groups on the aromatic ring. dhaq showed about 100 times more potent antiproliferative activity on cultured ... | 1983 | 6339045 |
| continuous-flow cultures as in vitro models of the ecology of large intestinal flora. | an anaerobic continuous-flow (cf) culture method has been developed which reproduces a number of bacterial interactions that occur in the large intestine of mice. these were determined in the following ways. (i) bacterial counts in smears stained with 37 specific fluorescent antisera showed that the numeric balance between 37 strict anaerobes isolated from conventional mice was maintained in cf culture of conventional mouse flora in the same manner as in conventional mice. (ii) mixed populations ... | 1983 | 6339387 |
| ascending, unobstructed urinary tract infection in mice caused by pyelonephritogenic escherichia coli of human origin. | a model for ascending unobstructed urinary tract infection was developed in mice to study the pathogenesis of urinary tract infection induced by escherichia coli associated with urinary tract infection in humans. specifically, the model was designed to monitor the initial stages of the infectious process, e.g., bacterial adhesion. mice were selected since the specificity and intensity of bacterial attachment of pyelonephritogenic e. coli strains to human and mouse uroepithelial cells were simila ... | 1983 | 6339403 |
| synthesis and biological activities of the z isomers of carbapenem antibiotics. | naturally occurring carbapenem antibiotics having a double bond in the side chain, when refluxed in chloroform containing quarternary alkylammonium halides, were converted into z isomers in high yields. the mechanism of this new equilibration involves intramolecular proton transfer from the carboxylic acid to the carbon alpha to the sulfur atom in the side chain as shown by deuterium-labeling experiments. some z isomers showed stronger protective effects in mice infected by escherichia coli o-11 ... | 1983 | 6341590 |
| differential expression of cloned mouse metallothionein sequences in escherichia coli. | a cdna for mouse hepatic metallothionein i has been cloned into pbr322 (mbikay et al., 1981). although this recombinant plasmid (m135) possesses the metallothionein sequence in the same reading frame as that of beta-lactamase, it fails to direct the synthesis of a fused beta-lactamase-metallothionein protein in escherichia coli. another plasmid (m244) was derived from m135 by deleting an internal 390-bp segment made of the 5' noncoding region of metallothionein, the dg-dc tail, and some beta-lac ... | 1983 | 6343048 |
| induction of indoleamine 2,3-dioxygenase in alveolar interstitial cells of mouse lung by bacterial lipopolysaccharide. | the cellular localization of indoleamine 2,3-dioxygenase was studied in the mouse lung after induction by lipopolysaccharide treatment. no significant indoleamine 2,3-dioxygenase activity was detected in alveolar macrophages and type ii epithelial cells, which were recovered by alveolar lavages and trypsin-treatment, respectively. to determine this enzyme activity in other types of lung cells, we prepared monodispersed lung cells (6.5 x 10(7) cells/lung) by incubation with 0.1% collagenase and 0 ... | 1983 | 6343379 |
| r plasmid dihydrofolate reductase with a dimeric subunit structure. | dihydrofolate reductase specified by plasmid r483 from a trimethoprim-resistant strain of escherichia coli has been purified 2,000-fold to homogeneity using dye-ligand chromatography, gel filtration, and polyacrylamide gel electrophoresis. the protein migrated as a single band on nondenaturing polyacrylamide gel electrophoresis and had a specific activity of 250 mumol/mg min(-1). the molecular weight was estimated to be 32,000 by gel filtration and 39,000 by ferguson analysis of polyacrylamide g ... | 1983 | 6350298 |
| [effect of a new drug on the immune system and its relation to induced infection in the mouse]. | 1983 | 6351183 | |
| a lipopolysaccharide and concanavalin a induce variations of serotonin levels in mouse tissues. | the administration of an escherichia coli lipopolysaccharide (lps), or an endotoxin into mice produced a variation in tissue serotonin (5ht) levels within 4.5 h. 5ht levels in the kidney and lung were decreased by the higher doses of lps, but those in the liver and spleen were increased even by lower doses of the agent. the increase in liver 5ht was most marked. such variations in 5ht levels were also produced by the administration of concanavalin a. in vitro experiments using extracts from live ... | 1983 | 6352285 |
| protection of calves against fatal enteric colibacillosis by orally administered escherichia coli k99-specific monoclonal antibody. | a monoclonal antibody (mca) to enterotoxigenic escherichia coli k99 antigen agglutinated k99+ enterotoxigenic e. coli strains b44 (o9:k30;k99;f41:h-) and b41 (o101:k99;f41:h-) grown at 37 degrees c but not at 18 degrees c. the mca, which was characterized as immunoglobulin g1, reacted specifically with k99 antigen in an enzyme-linked immunosorbent assay and precipitated radiolabeled k99 antigen. a total of 45 colostrum-fed and colostrum-deprived calves were used in three separate trials to deter ... | 1983 | 6358029 |
| selective expression of cloned middle-repetitive sequences in nuclear rna of mouse organs. | mouse middle-repetitive sequences have been cloned in the bacterial plasmid pbr322. the dna sequences, expressed only in nuclei, were screened by filter hybridization using nuclear rna as probes. several clones were expressed predominantly in the nuclear rna in certain types of organs. the copy numbers of typical middle-repetitive sequence clones in genomic dna were analyzed quantitatively and results showed that 10(3)-10(4) copies exist per haploid dna, indicating that they belong to a relative ... | 1983 | 6186489 |
| liposome-mediated insertion of intact dna into isolated nuclei. potential for a new in vitro transcription system. | dna molecules sequestered within negatively charged liposomes became nuclei-associated following interaction between isolated mouse plasmacytoma nuclei and liposomes. few if any liposomes appeared to adhere to washed nuclei following their interaction with liposomes, suggesting that dna was internalized. liposome-delivered, radioactive pbr322 dna re-extracted from nuclei appeared intact, whereas dna from nuclei incubated with naked dna was degraded. up to 2 x 10(10) d of dna were inserted into e ... | 1983 | 6196213 |
| receptors for human alpha and beta interferon but not for gamma interferon are specified by human chromosome 21. | we examined the proposed role of human chromosome 21 in determining the cellular sensitivity to human alpha, beta, and gamma interferons (huifn-alpha, -beta, and -gamma) and the expression of the receptors for the huifns with the use of mouse-human hybrid cells containing human chromosome 21. hybrid cells (wa17) containing three copies of human chromosome 21 showed specific displaceable binding of 125i-labeled huifn-alpha 2 (125i-huifn-alpha 2), which was not observed with mouse parent (a9) cell ... | 1984 | 6206498 |
| legionella pneumophila-induced blastogenesis of murine lymphoid cells in vitro. | legionella pneumophilia antigen preparations, either killed whole cell vaccine, a soluble sonic extract, or a purified large-molecular-weight somatic antigen, stimulated blastogenic responses by splenocytes from both normal and legionella-sensitized mice. graded amounts of the bacterial preparations, when added to cultures of normal spleen cells, resulted in increased uptake of thymidine into cellular dna, indicating that the preparations were mitogenic for normal mouse splenocytes. spleen cells ... | 1984 | 6360903 |
| correction of complex heteroduplexes made of mouse h-2 gene sequences in escherichia coli k-12. | we have prepared heteroduplexes between two plasmids that carry, in the same orientation, two h-2 cdna inserts, 1.15 and 1.0 kilobase long, respectively. their sequences encode two distinct class i transplantation antigens of the mouse and differ by 8% of their nucleotides. molecules with a rearranged array of restriction sites were found after transformation and cloning in an escherichia coli reca- host. nucleotide sequences showed that the rearranged molecules derived their nucleotides from th ... | 1984 | 6320192 |
| plasmidial maintenance in rodent fibroblasts of a bpv1-pbr322 shuttle vector without immediately apparent oncogenic transformation of the recipient cells. | a recombinant plasmid was constructed (pv69) which comprises a subgenomic fragment of bovine papilloma virus type 1 (bpv1) dna, part of plasmid pbr322 dna and a drug resistance gene expressed in both mammalian fibroblasts and escherichia coli. this gene (vv2) is a modified form of the bacterial neomycin resistance gene (neo) linked to the herpes simplex virus thymidine kinase (tk) promoter (plasmid pag60), to which the original bacterial neo promoter from transposon tn5 was added back, upstream ... | 1984 | 6325168 |
| [demonstration of thermostable e. coli enterotoxin using the suckling mouse test]. | 1984 | 6374842 | |
| dna polymerase i and dna primase complex in yeast. | chromatographic analysis of poly(dt) replication activity in fresh yeast extracts showed that the activities required co-fractionate with the yeast dna polymerase i. since poly(dt) replication requires both a primase and a dna polymerase, the results of the fractionation studies suggest that these two enzymes might exist as a complex in the yeast extract. sucrose gradient analysis of concentrated purified yeast dna polymerase i preparations demonstrates that the yeast dna polymerase i does sedim ... | 1984 | 6376490 |
| endotoxin-induced antitumor activity in the mouse is highly potentiated by muramyl dipeptide. | the ability of aqueous solutions of various endotoxin preparations, muramyl dipeptide (mdp) and combinations of endotoxin and mdp, to induce necrosis and regression of subcutaneous meth a transplants in mice and their toxicity were studied. while intravenously injected toxic endotoxins, in contrast to a detoxified preparation and to mdp, induced considerable necrosis and regression of their own, addition of mdp potentiated the antitumor potential of both toxic and detoxified endotoxins to the sa ... | 1984 | 6378362 |
| differential expression of macrophage effector functions: bactericidal versus tumoricidal activities. | macrophage populations may be induced to express tumoricidal or bactericidal activities following exposure to certain stimuli. an understanding of the differences in the stimulatory mechanisms and in the characteristics of the macrophages they affect will be facilitated by comparing functional activities of various macrophage populations. the experiments described here were conducted to determine whether injection of a single stimulus necessarily drives cells to express both tumoricidal and bact ... | 1984 | 6384403 |
| [characterization of enterotoxigenic escherichia coli of bovine origin by dna-dna colony hybridization]. | dna-dna colony hybridizations with a st1a probe were done on bovine enterotoxigenic escherichia coli strains and compared with the suckling mouse test. the results show that one fourth (7/24) of the strains positive in the baby mouse test do not hybridize the st1a probe and suggest the existence of another or other toxins among the bovine enterotoxigenic e. coli strains. | 1984 | 6385806 |
| chemical synthesis of an octadecapeptide with the biological and immunological properties of human heat-stable escherichia coli enterotoxin. | an eighteen-amino-acid peptide having the linear amino acid sequence of human heat-stable enterotoxin (st) has been synthesized by solid phase peptide synthesis. the purified peptide could be obtained in yields approaching 25% after purification by size, charge, and high-performance ligand chromatography. this material was pure and identical to native st by analytical high-performance ligand chromatography, amino acid analysis, paper electrophoresis and thin-layer chromatography. the formation o ... | 1984 | 6386477 |
| virulence factors of escherichia coli isolated from cows with acute mastitis. | a total of 184 escherichia coli isolates recovered from cows with acute mastitis were examined for recognized pathogenic mechanisms and virulence factors commonly found in pathogenic groups of e coli. a modification of the eng procedure (for detecting complement deficiencies in serum) was used to test for resistance to different animal sera. the sereny test (for invasiveness), infant mouse test (for heat-stable enterotoxin), and y-1 adrenal tumor cell assay (for heat-labile enterotoxin) were use ... | 1984 | 6388441 |
| does enteropathogenic escherichia coli produce heat-labile enterotoxin, heat-stable enterotoxins a or b, or cholera toxin a subunits? | although most enteropathogenic escherichia coli strains do not produce recognized enterotoxins, we wished to examine whether they produce any factors like heat-stable enterotoxin b or cholera toxin active subunits that might be missed by conventional assay methods. e. coli strains e851 (o142) and e2348 (o127) that had caused diarrhea in volunteers were negative for heat-labile enterotoxin and heat-stable enterotoxin a in chinese hamster ovary cell and suckling mouse assays, failed to cause secre ... | 1984 | 6389354 |
| sequential study of bacterial clearance in experimental cystitis. | clearance of escherichia coli in experimental cystitis was studied in the diuresing mouse model. urine was collected daily; sediment was isolated by cytocentrifugation and either stained or treated with fluorescent antibodies directed against mouse immunoglobulins. during the initial phase of the infection the bacteria were either free and dispersed or adhering to epithelial cells but not generally to polymorphonuclear cells (pmns). subsequently, the bacteria adhered to each other, to epithelial ... | 1984 | 6389872 |
| high-affinity microtubule protein-higher organism dna complexes. many-fold enrichment in repetitive mouse dna sequences comprised of satellite dnas. | we have examined aspects of the interaction of cycled microtubule protein preparations with 35s-labeled mouse dna tracer in a competition system with unlabelled competitor e. coli or mouse dna. the nitrocellulose filter binding assay was used to measure interaction by scintillation counting. dna molecular weight affected the levels of filter retained 35s-labelled mouse tracer dna. filter retention levels increased if 35s-labelled mouse dna tracer size was increased, and the filter binding level ... | 1984 | 6391551 |
| mercury-resistant plasmids in bacteria from a mercury and antimony deposit area. | most bacterial cells (pseudomonas, acinetobacter) obtained from the soil at the khaidarkan mercury and antimony mine (kirghiz ussr) contain r plasmids with mercury (hgcl2) resistance determinants. the plasmids have a large molecular mass (about 100 md, though smaller ones also occur), and at least some of them are transmissive. many of the hgr bacteria also display an elevated antimony (sbcl3) resistance, though this trait was not shown to be plasmid-dependent. there are practically no hgr plasm ... | 1984 | 6394954 |
| relationship between pathogenicity in footpad lesion test and invasiveness in escherichia coli. | using a previously described virulence test, we established a correlation between escherichia coli invasiveness and its ability to cause lesions in mouse footpads. the footpad lesion test thus represents a simple-to-use tool for screening pathogenic and invasive strains of e. coli. | 1984 | 6398010 |
| quantification of large c3 fragments as an index of complement activation in mice. ii. in vivo studies. | a method which enables to evaluate the mouse c3 activation has been used to study the activation of the complement system in c57bl/6 mice injected with cobra venom factor, with escherichia coli, and with bacterial lipopolysaccharide. it was found that this method was able to detect the complement activation early, at a time when total levels of c3-reacting molecules had not yet decreased. | 1984 | 6399880 |
| androgen induction of ornithine decarboxylase mrna in mouse kidney as studied by complementary dna. | to investigate the mechanisms by which androgens regulate ornithine decarboxylase (orndcase; l-ornithine carboxy-lyase, ec 4.1.1.17) in mouse kidney, a cdna clone encoding orndcase mrna was prepared. purification of orndcase mrna from kidneys of androgen-treated mice was accomplished by immunoadsorption of renal polysomes to a protein a-sepharose column and enrichment for poly(a)-containing rna by oligo(dt)-cellulose. double-stranded cdna synthesized from this mrna was inserted into the pst i si ... | 1984 | 6366788 |
| possible ideal lac operator: escherichia coli lac operator-like sequences from eukaryotic genomes lack the central g x c pair. | five dna fragments have been cloned from yeast, chicken, and mouse dna that titrate lac repressor in an escherichia coli lac+ i+z+ wild-type strain when on a multi-copy plasmid. the five repressor-binding sequences have been identified by dna sequence determinations and dnase cleavage-inhibition patterns. they share the 14-base-pair symmetrical consensus sequence 5' t-g-t-g-a-g-c:g-c-t-c-a-c-a 3' (the colon represents the center of symmetry), which is an inverted repeat of 7 base pairs of the le ... | 1984 | 6369330 |
| identification of a cdna clone encoding a mature blood stage antigen of plasmodium falciparum by immunization of mice with bacterial lysates. | a cdna library was constructed in pbr322 using mrna from blood stages of a papua new guinean isolate of plasmodium falciparum. expression of parasite antigens was not directly detectable by conventional immunological assays. to circumvent this, mice were immunized with lysates of cdna clones, and the antisera raised were assayed for anti-parasite reactivity. one cdna clone was identified which reliably elicited antibodies to p. falciparum. the mouse antisera were used to characterize the native ... | 1984 | 6370681 |
| phagocytosis and killing of escherichia coli x43 by individual resident mouse peritoneal macrophages assessed by an autoradiographic technique. | an autoradiographic technique for the determination of viable bacteria in individual cells is described, based on the incorporation of [3h]thymidine into the dna of viable escherichia coli x43, following phagocytosis by resident mouse peritoneal macrophages. the results of the autoradiographic technique were in overall agreement with viable colony counts. investigation of the killing of e. coli x43 with the autoradiographic technique showed that the percentage viable bacteria tended to be the sa ... | 1984 | 6371139 |
| promotion by burn stress of the translocation of bacteria from the gastrointestinal tracts of mice. | a mouse burn model was established to test the effect of nonlethal thermal injury on the translocation of indigenous bacteria from the gastrointestinal (gi) tract to other organs. specific pathogen-free (spf) mice were given 15% or 30% total body surface area burns, and the mesenteric lymph nodes (mlns), spleens, livers, blood, and peritoneal cavities were cultured for translocated bacteria at various time intervals. no viable aerobic, facultatively anaerobic, or strictly anaerobic bacteria of t ... | 1984 | 6230067 |
| effects of interferon-alpha/beta and interferon-gamma preparations on phagocytosis by mouse peritoneal macrophages. | the influence of murine alpha/beta-interferon (mu ifn-alpha/beta) and murine gamma-interferon (mu ifn-gamma) preparations on the attachment and ingestion phase of phagocytosis by mouse peritoneal macrophages (mpm) was studied. a non-opsonized strain of escherichia coli, igg-opsonized e. coli, and sheep erythrocytes opsonized with igg (e-igg) and igm plus complement factor c3b (e-igmc) were used as test particles. pretreatment of mpm with 10(2)-10(3) u/ml of mu ifn-alpha/beta for 24 h enhanced bo ... | 1984 | 6236548 |
| structure and distribution of alu family sequences or their analogs within heterogeneous nuclear rna of hela, kb, and l cells. | we studied the distribution of repetitive sequence elements capable of forming double-stranded regions in nuclear rna of hela, kb, and l cells. in human rna populations, we called these regions duplex alu family rna (dafrna) because they represent transcripts of the highly reiterated family of dna regions known as "alu family dna" (rubin et al., nature (london) 284:372-374, 1980). although the dafrna populations of both human cell lines (hela and kb) have low sequence complexity, they represent ... | 1984 | 6700593 |
| motility as a factor in bowel colonization by roseburia cecicola, an obligately anaerobic bacterium from the mouse caecum. | roseburia cecicola strain gm is a motile obligate anaerobe that was isolated from mouse caecal mucosa. twenty-five strains of motility mutants were obtained from populations of strain gm (wild-type) that had been exposed to uv light. unlike gm cells, mutant bacteria were either non-motile and non-flagellated (fla-) or migrated slowly or atypically in semi-solid medium. strain gm and two mutant strains, sls (fla-) and wes (atypically motile), were used in mouse colonization experiments. in separa ... | 1984 | 6707607 |
| isolation of short interspersed repetitive dna sequences present in the regions of initiation of mammalian dna replication. | nascent dna chains containing the putative replication origins were isolated from cells of human embryonic lung fibroblasts, hela, ehrlich ascites tumour and guerin ascites tumour as described earlier [ russev , g., and vassilev , l. (1982) j. mol. biol. 161, 77-87]. it was demonstrated that the synthesis of these nascent chains correlated with the ability of cells to initiate semiconservative dna replication. reassociation and electrophoretic analysis showed that the nascent chains from all fou ... | 1984 | 6723654 |
| effect of asparaginase on cell membranes of sensitive and resistant mouse lymphoma cells. | high concentrations of escherichia coli asparaginase (80 u/ml) altered the binding of concanavalin a (con a) to l 5178y murine lymphoma cells that are sensitive to the cytotoxic action of this enzyme. incubation of the asparaginase sensitive line in asparagine-free media or media containing acinetobacter glutaminase-asparaginase did not alter the con a binding of these cells. escherichia coli asparaginase had no effect on con a binding of two asparaginase resistant l5178y cell lines that were is ... | 1984 | 6724617 |
| induction of immune and adjuvant immunoglobulin g responses in mice by brucella lipopolysaccharide. | the immunogenic and adjuvant properties of brucella abortus and escherichia coli lipopolysaccharides (lpss) were studied in endotoxin-responsive, athymic, and euthymic balb/c mice and in responsive c3h/heau mice and congenic nonresponsive c3h/hej mice. consistent with previous reports, e. coli lps did not stimulate significant primary or secondary antibody responses in c3h/hej mice and induced the production of immunoglobulin m (igm) and low levels of igg in c3h/heau mice. in contrast, b. abortu ... | 1984 | 6434430 |
| pharmacokinetic and experimental data on beta-lactam antibiotics in the treatment of patients. | the in vitro and animal model studies on optimal dosage of the newer beta-lactams are summarized and put into historical perspective. they provide a rationale for dosage schedules that continuously maintain inhibitory serum and tissue concentrations throughout the dosage interval. in vitro studies on the post-antibiotic effect (pae) with beta-lactams revealed only short time periods of post-antibiotic growth suppression with gram-positive cocci and no post-antibiotic effect with gram-negative ba ... | 1984 | 6441711 |
| therapeutic efficacy of a new cephamycin, mt-141, in compromised mice. | the antibacterial activity of mt-141 against escherichia coli and proteus morganii in compromised mice was investigated and compared with that of latamoxef, cefmetazole and cefoxitin. the bactericidal activity of mt-141 in short-term contact with e. coli and p. morganii was markedly enhanced when combined with mouse serum, and the activity of mt-141 was greater than the activities of the three reference drugs. the antibacterial activities of mt-141 in the liver, spleen and kidney of neutropenic ... | 1984 | 6441793 |
| development of a competitive enzyme-linked immunosorbent assay (elisa) for escherichia coli heat-stable enterotoxin (sta). | a sensitive competitive enzyme-linked immunosorbent assay (elisa) was developed to detect the low molecular weight heat-stable enterotoxin (sta) in culture supernatant fluids of enterotoxigenic escherichia coli (etec). competitive inhibition was observed between sta in solution and a glutaraldehyde-coupled sta-human serum albumin (hsa) conjugate bound to microtiter wells when antiserum raised against a glutaraldehyde-coupled sta-bovine serum albumin (bsa) conjugate was used as detecting antibody ... | 1984 | 6520401 |
| molecular cloning of dna sequences complementary to mouse thymidylate synthase messenger rna. | we describe the isolation of recombinant cdna clones containing sequences corresponding to mouse thymidylate synthase mrna. double-stranded cdna was made from poly(a+) rna isolated from the 5-fluoro-2'-deoxyuridine-resistant mouse cell line lu3 -7 that overproduces thymidylate synthase 50- to 100-fold as compared to the parental mouse 3t6 fibroblasts. the cdna was inserted into pbr322 using the poly(dc)-poly(dg) tailing procedure and transformed into escherichia coli hb101. a library of 30,000 c ... | 1984 | 6144683 |
| a virulence plasmid in escherichia coli enterotoxigenic for humans: intergenetic transfer and expression. | we studied the colonization-factor antigen i (cfa/i) fimbriae- and heat-stable enterotoxin (st)-coding plasmid of enterotoxigenic escherichia coli (strain h10407, serotype o78:h11) pathogenic for humans. with use of conjugal-transfer system of e. coli h10407 and transposon-labeling techniques, the virulence plasmid was shown to be transferable to many species of the family enterobacteriaceae, including the enteropathogens, shigella and salmonella species, and the opportunistic pathogens, klebsie ... | 1984 | 6149247 |
| ten years-long survey on pathogen status of mouse and rat breeding colonies. | eleven pathogens including p. aeruginosa, salmonella spp., e. coli o115a, c: k(b), p. pneumotropica, b. bronchiseptica, c. kutscheri, tyzzer's organism, m. pulmonis, sendai virus, mhv and syphacia spp. were surveyed in 217 mouse and rat breeding colonies during 1972-1981. in conventional animals, p. pneumotropica and/or syphacia spp. were detected in nearly 90% of 89 mouse and 64 rat colonies. sendai virus, m. pulmonis, p. aeruginosa and mhv were positive in 51.7 to 23.6% of the colonies, and ty ... | 1984 | 6088258 |
| human renin gene: structure and sequence analysis. | the complete protein precursor of human kidney renin has been determined from the sequence of cloned genomic dna. the gene spans 12 kilobases of dna and is interrupted by eight intervening sequences. the nine regions (exons) encoding the protein were mapped with a mouse renin cdna probe, synthetic oligonucleotide probes, and by hybridization of genomic restriction fragments to a 1600-nucleotide human kidney mrna. the predicted 403-amino acid preprorenin consists of mature renin and a 66-residue ... | 1984 | 6089171 |
| promoter dependence of enhancer activity. | the interaction of enhancers with different promoters was studied by measuring the influence of two enhancers (from simian virus 40 and from harvey sarcoma virus) on the activity of expression vectors that are identical except for their promoter region. the promoters examined were from the simian virus 40 early region, with or without its own 72-base-pair repeat, and the mouse beta major-globin gene. it is clear that the promoter acted upon strongly influences the level of activity of an enhance ... | 1984 | 6092930 |
| general recombination mechanisms in extracts of meiotic cells. | reca-like proteins have been purified from somatic and meiotic cells of mouse and lily. the rec proteins have been designated "s-rec" and "m-rec" to indicate their respective tissues of origin. the two proteins differ in molecular weight and in their response to temperature, the latter being consistent with the optimal temperature for physiological function of their tissues of origin. there is a major increase in m-rec protein with the entry of cells into meiosis, the peak of activity being earl ... | 1985 | 2935376 |
| selective transfer of individual human chromosomes to recipient cells. | two hypoxanthine phosphoribosyltransferase-deficient human cell lines, d98/ah-2 and ht1080-6tg, were stably transfected with psv2 gpt, a plasmid containing the selectable marker escherichia coli xanthine-guanine phosphoribosyl transferase (eco gpt). hypoxanthine-aminopterin-thymidine-resistant transformants arose with a frequency of ca. 10(-6) and contained mostly single, but occasionally multiple, copies of the plasmid sequences. these transformants actively express the eco gpt marker. single c ... | 1985 | 3982414 |
| the influence of murine macrophage-conditioned medium on cloning efficiency, antibody synthesis, and growth rate of hybridomas. | murine b-cell hybridomas made with the p3x63-ag8.653 myeloma showed increases in cloning efficiency and efficiency of growth in hypoxanthine-aminopterin-thymidine (hat) medium of 50-100-fold in the presence of medium conditioned by primary mouse peritoneal macrophages (mcm). similar effects were elicited by mcm from 3 continuous macrophage lines. the j774a.1 line conditioned the medium as efficiently as primary macrophages without induction. conditioning by the p388d1 line was several-fold less ... | 1985 | 3998479 |