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At least 595 records · Page 33Linked to original sources
PubMed1996

A novel plasmid from Staphylococcus epidermidis specifying resistance to kanamycin, neomycin and tetracycline.

The naturally occurring plasmid pSTS7 from Staphylococcus epidermidis mediated resistance to tetracycline via a tetL gene and to kanamycin and neomycin via an aadD gene. Plasmid pSTS7 showed partial restriction map and sequence homology to the previously described tetracycline resistance plasmid pNS1981 from Bacillus subtilis and to the kanamycin/neomycin/bleomycin resistance plasmid pUB110 from S. aureus. Sequence analysis of the regions flanking the two resistance genes in pSTS7 led to the identification of a novel site for interplasmid recombination which could explain the derivation of pSTS7 from the incompatible pNS1981- and pUB110-like parental plasmids under tetracycline-selective pressure.

Amino Acid Sequence↗
PubMed1991

Cytotoxicity of human natural killer (NK) cell subsets for Plasmodium falciparum erythrocytic schizonts: stimulation by cytokines and inhibition by neomycin.

Quantification of human peripheral blood NK subsets has been made in a group of Kenyan adults and children with acute P. falciparum malaria. Results were compared with data obtained from three age- and sex-matched control cohorts: parasitaemic but asymptomatic children; aparasitaemic children and adults; and adult Caucasians with no previous history of malaria. Separated NK subsets were tested in vitro for cytotoxicity to erythrocytic schizonts of P. falciparum in the presence and absence of cytokines. There was a statistically significant quantitative and qualitative depression of the CD3-CD56+ subset in patients with acute malaria and this was accompanied by an expansion of the 'non-functional' CD3-CD57+CD16-CD56- subset. Both CD3-CD16+ and CD3-CD56+ NK cells from all patients and donors lysed schizonts, and this cytotoxicity was enhanced by the addition of recombinant interferon-alpha and/or IL-2, notably with the CD3-CD56+ subset. Interestingly, asymptomatic donors had the highest levels of CD3-CD56+ NK cells, which also demonstrated an enhanced response to cytokine stimulation. Cytotoxicity to schizonts was accompanied by the release of soluble NK cell lytic factors. Neomycin suppressed cytotoxicity in a dose-dependent manner, indicating that the lysis of schizonts by NK cells involves phospholipase C-mediated phosphoinositide metabolism. Our findings define a role for NK cells in immunity to malaria through the lysis of infected erythrocytes as a first-line defence against the parasite.

Animals↗
PubMed1992

The decomposition of phenylmercuric nitrate caused by disodium edetate in neomycin eye drops during the process of heat sterilization.

High-performance liquid chromatographic (HPLC) assays have been developed for phenylmercuric nitrate and mercuric ions in the presence of disodium edetate. Application of these methods to neomycin eye drops of the Pharmaceutical Codex and Australian Pharmaceutical Formulary, which contain both phenylmercuric nitrate and disodium edetate, show that edetate promotes approximately 20% decomposition of the phenylmercuric nitrate in the drops of the Pharmaceutical Codex but little in the drops of the Australian Pharmaceutical Formulary during sterilization by the recommended method. The reason for the stability of the organomercurial in the Australian product was determined as being due to the presence of sodium chloride in the formulation.

Chromatography, High Pressure Liquid↗
PubMed1990

Herpes simplex virus type-1-induced stimulation of ribosomal protein S6 phosphorylation is inhibited in neomycin-treated human epidermoid carcinoma 2 cells and in ras-transformed cells.

Neomycin, an inhibitor of inositol phospholipid turnover, prevents Herpes-simplex-virus-type-1 (HSV-1)-induced stimulation of ribosomal protein S6 phosphorylation, but does not impair the S6 phosphorylation induced by serum. Long-term treatment with phorbol 12-myristate 13-acetate, which down-regulates protein kinase C activity, does not inhibit virus-induced S6 phosphorylation. In ras-transformed cells, S6 phosphorylation is not stimulated after HSV-1 infection. These results suggest that activation of the inositol phospholipid pathway is involved in the HSV-1-induced stimulation of S6 phosphorylation. However, protein kinase C activation does not appear to be necessary for HSV-1-induced S6 phosphorylation.

Animals↗
PubMed1997

Neomycin- and spectinomycin-resistance replacement vectors for Bacillus subtilis.

A plasmid is described for Bacillus subtilis that facilitates replacement of the widely used neomycin resistance gene (neo) with a spectinomycin resistance (spcE) gene. A second plasmid is described that facilitates replacement of spcS, associated with mini-Tn10 mutagenesis in B. subtilis, with neo. These plasmids can also function as integrative vectors for B. subtilis. They expand the scope of strain construction and gene analysis in B. subtilis.

Anti-Bacterial Agents↗
PubMed1999

Acid sensitivity of neomycin-resistant mutants of Oenococcus oeni: a relationship between reduction of ATPase activity and lack of malolactic activity.

Mutants of Oenococcus oeni were isolated as spontaneous neomycin-resistant mutants. Three of these mutants harbored a significantly reduced ATPase activity that represented 50% of that of the wild-type strain. Their growth rates were also impaired at pH 5.3 (46-86% of the wild-type level). However, the profiles of sugar consumption appeared identical to those of the parental strain. At pH 3.2, all the mutant strains failed to grow and a drastic decrease in viability was observed after an acid shock. Surprisingly, all the isolated mutants were devoid of malolactic activity. These results suggest that the ATPase and malolactic activities of O. oeni are linked to each other and play a crucial role in the mechanism of resistance to an acid stress.

Adenosine Triphosphatases↗
PubMed1969

m-Hydroxyphenylacetic acid formation from L-dopa in man: suppression by neomycin.

The increased excretion of m-hydroxyphenylacetic acid in the urine of patients with parkinsonism being treated with L-dopa was reduced by gut sterilization with neomycin. The p-de-hydroxylation step is thus brought about solely by the action of gut flora; the pathway is unlikely to be involved in the events within the brain leading to the therapeutic benefit effected by L-dopa.

Dihydroxyphenylalanine↗
PubMed1973

Transmissible resistance to penicillin G, neomycin, and chloramphenicol in Rhizobium japonicum.

The genetic basis for resistance to a number of antibiotics was examined in Rhizobium japonicum. Resistance to penicillin G, neomycin, and chloramphenicol appears to be mediated by an extrachromosomal element similar to that found in the Enterobacteriaceae. Resistance to these antibiotics was eliminated from cells by treatment with acridine orange, and resistance to all three antibiotics could be transferred en bloc to Agrobacterium tumefaciens under conditions excluding transformation or transduction as possible genetic mechanisms.

Acridines↗
PubMed2006

Binding of neomycin-class aminoglycoside antibiotics to mutant ribosomes with alterations in the A site of 16S rRNA.

Aminoglycoside antibiotics that bind to the aminoacyl-tRNA site (A site) of the ribosome are composed of a common neamine core in which a glycopyranosyl ring is attached to position 4 of a 2-deoxystreptamine moiety. The core is further substituted by one (ribostamycin), two (neomycin and paromomycin), or three (lividomycin A) additional sugars attached to position 5 of the 2-deoxystreptamine. To study the role of rings III, IV, and V in aminoglycoside binding, we used isogenic Mycobacterium smegmatis DeltarrnB mutants carrying homogeneous populations of mutant ribosomes with alterations in the 16S rRNA A site. MICs were determined to investigate drug-ribosome interactions, and the results were compared with that of the previously published crystal structure of paromomycin bound to the ribosomal A site. Our analysis demonstrates that the stacking interaction between ring I and G1491 is largely sequence independent, that rings III and IV each increase the strength of drug binding to the ribosome, that ring IV of the 6'-NH3+ aminoglycosides compensates for loss of interactions between ring II and U1495 and between ring III and G1491, that the aminoglycosides rely on pseudo-base pairing between ring I and A1408 for binding independently of the number of sugar rings attached to the neamine core, that addition of ring V to the 6'-OH 4,5-aminoglycoside paromomycin does not alter the mode of binding, and that alteration of the U1406.U1495 wobble base pair to the Watson-Crick interaction pair 1406C-1495G yields ribosomal drug susceptibilities to 4,5-aminoglycosides comparable to those seen with the wild-type A site.

Anti-Bacterial Agents↗
PubMed1996

Neomycin resistance as a selectable marker in Methanococcus maripaludis.

We cloned the aminoglycoside phosphotransferase genes APH3'I and APH3'II between the Methanococcus voltae methyl reductase promoter and terminator in a plasmid containing a fragment of Methanococcus maripaludis chromosomal DNA. The resulting plasmids encoding neomycin resistance transformed M. maripaludis at frequencies similar to those observed for pKAS102 encoding puromycin resistance. The antibiotic geneticin was not inhibitory to M. maripaludis.

Anti-Bacterial Agents↗
PubMed1965

Increase in sensitivity for the assay of neomycin in milk.

A study was conducted to design a more sensitive and flexible technique for the assay of neomycin in milk. Sterile Antibiotic Assay medium (Difco; 15 ml) was poured into glass petri dishes with aluminum tops equipped with absorbent discs. Seed agar (4 ml; containing 1% sodium chloride) inoculated with standardized amounts of the test organism (Staphylococcus epidermidis ATCC 12228) was laid over the hardened base agar, and stainless-steel cylinders were placed equal distances apart in the agar. The plates were refrigerated for 30 min and the cups were removed in an atmosphere of minimal contamination. The resultant holes were sealed with melted agar. After preparation, the holes were used for assay procedures. Samples to be assayed were pipetted into the holes and the plates were refrigerated for 90 min at 4 C. Plates were incubated for 18 to 20 hr at 32 C. The zones of inhibition were recorded and compared with a standard curve. The approximate sensitivity of this method was 0.05 mug/ml.

Animals↗
PubMed1968

Inactivation of kanamycin, neomycin, and streptomycin by enzymes obtained in cells of Pseudomonas aeruginoa.

Ten strains of Pseudomonas aeruginosa were disrupted and centrifuged. The supernatant fluids from centrifugation at 105,000 x g contained enzymes inactivating kanamycin, neomycin, and streptomycin in the presence of adenosine triphosphate. Kanamycin-inactivating enzyme was precipitated with ammonium sulfate at 66% of saturated concentration, and the inactivated kanamycin was shown to be kanamycin-3'-phosphate in which the C-3 hydroxyl group of 6-amino-6-deoxy-d-glucose moiety was phosphorylated. This is identical with kanamycin inactivated by Escherichia coli carrying R factor. Streptomycin-inactivating enzyme was precipitated with ammonium sulfate at 33% of saturated concentration.

Adenosine Triphosphate↗
PubMed1999

Comparison of selective broth medium plus neomycin-nalidixic acid agar and selective broth medium plus Columbia colistin-nalidixic acid agar for detection of group B streptococcal colonization in women.

The combination of neomycin-nalidixic acid (NNA) agar and a selective broth medium (SBM) has recently been shown to improve the sensitivity of screening cultures for group B streptococcal (GBS) carriage in women. Because of the relatively high cost of NNA agar, a study was initiated to determine whether Columbia colistin-nalidixic acid (CNA) agar would be an equally sensitive, more economical alternative. A total of 580 cervical-vaginal and/or rectal specimens submitted for detection of GBS were included in the study. Each was plated onto NNA and CNA agar and then inoculated into SBM. GBS were recovered from 95 of 580 (16.4%) specimens, including 61 isolates from CNA, 74 from NNA, 73 from the CNA-SMB combination, and 86 from the NNA-SMB tandem. Of those, 22 isolates were recovered on NNA but not CNA, 9 were cultured on CNA but not NNA, 52 were isolated on both media, and 12 were recovered from subcultures of SBM only. The overall sensitivity of CNA alone (64. 2%) was statistically significantly less than that of NNA agar (77. 9%), as was the sensitivity of combination of CNA plus SBM (76.8%) compared to that of NNA plus SBM (90.5%). Based on these findings, CNA should not be considered an acceptable alternative to NNA for the detection of GBS colonization in women despite potential cost savings.

Agar↗
PubMed1983

An upstream regulatory domain of avian tumor virus long terminal repeat is required for the expression of a procaryotic neomycin gene in eucaryotic cells.

The regulatory elements present in the long terminal repeat (LTR) of avian sarcoma virus DNA were analyzed by recombinant DNA techniques coupled with DNA-mediated gene transfer in avian as well as mammalian cells. For this purpose, the neomycin resistance gene from transposon Tn5 was inserted downstream from the avian sarcoma virus LTR, and the recombinant plasmid DNA was introduced into cells by the calcium phosphate technique. Cells resistant to the drug G-418 were selected. Analysis of the RNA transcripts made in vivo in these transformants indicated that initiation and termination of the transcripts occurred in the LTR sequences. Deletions were then introduced into the LTR, and their effect on transcription was also studied. These results allowed us to identify a strong regulatory sequence between nucleotides -299 and -114 in the LTR of avian sarcoma virus.

Animals↗
PubMed1985

Neomycin resistance as a dominant selectable marker for selection and isolation of vaccinia virus recombinants.

The antibiotic G418 was shown to be an effective inhibitor of vaccinia virus replication when an appropriate concentration of it was added to cell monolayers 48 h before infection. Genetic engineering techniques were used in concert with DNA transfection protocols to construct vaccinia virus recombinants containing the neomycin resistance gene (neo) from transposon Tn5. These recombinants contained the neo gene linked in either the correct or incorrect orientation relative to the vaccinia virus 7.5-kilodalton gene promoter which is expressed constitutively throughout the course of infection. The vaccinia virus recombinant containing the chimeric neo gene in the proper orientation was able to grow and form plaques in the presence of G418, whereas both the wild-type and the recombinant virus with the neo gene in the opposite polarity were inhibited by more than 98%. The effect of G418 on virus growth may be mediated at least in part by selective inhibition of the synthesis of a subset of late viral proteins. These results are discussed with reference to using this system, the conferral of resistance to G418 with neo as a positive selectable marker, to facilitate constructing vaccinia virus recombinants which contain foreign genes of interest.

Animals↗
PubMed1971

An ultrastructural study of the effect of neomycin on the colon in the human subject and in the conventional and the germ-free mouse.

An electron microscopic study of the colon of normal mice and human subjects and those treated with neomycin is reported; there is a close resemblance between the mouse and human colons. After rapid disinfection of the colon, there is epithelial cell damage due to a toxic effect of the drug, a reduction in epithelial turnover accompanying the change in flora, and an important reduction in the cellularity of the lamina propria mainly due to a reduction in inflammatory cells. The changes in the lamina propria probably represent changes in the antipathogenetic defences of the host.

Animals↗