Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neomycin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1994

Neomycin: a novel potent blocker of communication between T-tubule and sarcoplasmic reticulum.

Ca2+ release from the sarcoplasmic reticulum (SR) was induced in isolated triads by direct stimulation of the SR moiety by polylysine, or stimulation via chemical depolarization of the transverse tubule (T-tubule) moiety. Polylysine-induced release was blocked by neomycin with an IC50 (the concentration for half-maximal inhibition) of 0.3 microM. However, the IC50 for neomycin block of depolarization-induced Ca2+ release sharply decreased in a voltage-dependent fashion, and it was 5.3 nM at a maximal extent of T-tubule depolarization. These results suggest that the high affinity binding of neomycin to the triad leads to the specific blocking of the signal transmission from T-tubule to SR.

Animals↗
PubMed1985

Levels of lipoprotein Lp(a) decline with neomycin and niacin treatment.

Total and low density lipoprotein cholesterol concentration reduction in patients with markedly increased levels of these substances, leads to a decline in the incidence of myocardial infarction and death. A unique cholesterol-rich lipoprotein, lipoprotein Lp(a), has been identified which not only can be confused with low density lipoproteins, but has also been associated with premature cardiovascular disease. Using the cholesterol-lowering drugs neomycin and niacin in 14 type II hyperlipoproteinemic subjects, we determined the effect of lipid-lowering therapy on lipoprotein Lp(a) concentrations. Neomycin (2g/day) reduced low density lipoprotein cholesterol and lipoprotein Lp(a) concentrations by 23% and 24%, respectively. Combination therapy with neomycin (2 g/day) and niacin (3 g/day) induced a 48% decline in low density lipoprotein cholesterol levels and a 45% reduction in the concentration of lipoprotein Lp(a). These changes in lipoprotein Lp(a) levels were associated with a striking decline in the intensity of the slow pre-beta-lipoprotein fraction determined Lp(a) by lipoprotein electrophoresis. This slow pre-beta-lipoprotein fraction contained Lp(a) determined by immunofixation. These observations indicate that lipoprotein Lp(a) concentrations can be altered pharmacologically and that the progression of cardiovascular disease may be altered through changes in lipoprotein (a) levels.

Adult↗
PubMed1986

Mouse mammary tumor virus mediated transfer and expression of neomycin resistance to infected cultured cells.

The mammary gland specific, glucocorticoid controlled expression of MMTV makes it an ideal candidate for the basis of a nonpromiscuous regulated retroviral vector system. We have previously constructed an MMTV proviral variant that gives rise to virus particles upon introduction into cultured cells. This was used to construct a defective MMTV provirus in which the MMTV env gene was replaced by the neomycin resistance gene under the control of the herpes simplex thymidine kinase promotor. The defective provirus was packaged after transfection into two distinct MMTV producing cell lines. Conditioned medium from these cells contains virus particles which are able to infect cells of fibroblast and epithelial origin and to confer neomycin resistance upon them. This indicates that the defective MMTV provirus contains the sequences required for packaging of the genomic viral RNA. Transfection of the same MMTV-neo recombinant provirus into the MoMLV packaging cell line, psi 2, did not result in any infectious virus particles. Thus the packaging signals for MMTV and MoMLV appear to be distinct. Analysis of the MMTV infected cells reveals the presence of the MMTV-neo recombinant provirus. Expression of both MMTV and neomycin is detectable and augmented when the infected cells are grown in the presence of glucocorticoid hormone.

Animals↗
PubMed1985

Phosphoinositides in mitogenesis: neomycin inhibits thrombin-stimulated phosphoinositide turnover and initiation of cell proliferation.

Thrombin stimulates 32Pi incorporation into phosphatidylinositol 4-phosphate (PIP), phosphatidylinositol 4,5-bis-phosphate (PIP2), and phosphatidylinositol (PI), and initiates DNA synthesis in hamster (NIL) fibroblasts at a half-maximal concentration of 125 ng/ml. Neomycin, which binds PIP2 and PIP, inhibits both thrombin-stimulated initiation of cell proliferation and 32P pI incorporation into at concentrations above 2 mM without affecting thrombin binding, thymidine uptake, or cellular protein synthesis. At lower concentrations, neomycin inhibits thrombin-stimulated release of inositol 1,4,5-trisphosphate (IP3), by selectively binding PIP2, but does not inhibit 32P incorporation into PI or initiation of DNA synthesis. Phosphoinositide recycling and diacylglycerol release therefore appear necessary for initiation of cell proliferation by thrombin. IP3-stimulated Ca++ mobilization may not be required for thrombin mitogenesis, however, since neomycin can block IP3 release without inhibiting initiation.

Animals↗
PubMed1995

Effects of contact sensitizers neomycin sulfate, benzocaine and 2,4-dinitrobenzene 1-sulfonate, sodium salt on viability, membrane integrity and IL-1 alpha mRNA expression of cultured normal human keratinocytes.

The toxic effect of three potential contact sensitization chemicals [the aminoglycosidic antibiotic neomycin sulfate, the local anaesthetic benzocaine and the primary sensitizer 2,4-dinitrobenzene 1-sulfonate, sodium salt (DNBS)], on cultured human keratinocytes was examined. The three chemicals were compared with respect to their cytotoxic potential (determined by crystal violet staining assay), their membrane disruptive potential ([3H]arachidonic acid release assay), and their effects on interleukin 1 alpha (IL-1 alpha) mRNA expression [reverse transcription-polymerase chain reaction (RT-PCR)]. At the concentrations used, neomycin sulfate (0.004-0.32%) and benzocaine (0.0165-0.165%) did not show relevant cytotoxicity or membrane perturbation. On the other hand, DNBS (0.001-1%) caused a significant dose-dependent cytotoxic response at concentrations higher than 0.1%, while the [3H]arachidonic acid release assay indicated absence of membrane perturbation activity in all the range of DNBS concentrations examined. The effects of the three sensitizers on IL-1 alpha mRNA expression were varied; neomycin sulfate caused a dose-dependent induction of IL-1 alpha mRNA, benzocaine did not significantly affect its signal, and DNBS suppressed IL-1 alpha gene expression.

Arachidonic Acid↗
PubMed1985

Progressive ototoxicity of neomycin monitored using derived brainstem response audiometry.

Progressive hearing loss following the systemic administration of neomycin was investigated using derived brainstem response audiometry. Cats were given three to five times the maximum recommended clinical dose of neomycin over a period of 10 days. Their hearing was monitored prior to and during the administration of the drug, and periodically following its completion. The results of this study showed that the induced hearing loss generally proceeded from high to low frequencies as an advancing lesion, with regions apical to the lesion functioning normally. Although considerable variability in response to the drug existed among animals, the evoked responses from both ears of each animal showed close bilateral symmetry during the deafening process. Furthermore, the present results highlight the long-term ongoing ototoxicity associated with neomycin, and the importance of monitoring high frequencies for initial signs of an aminoglycoside induced hearing loss.

Animals↗
PubMed1989

Flow microcalorimetric assay of antibiotics--IV. Polymyxin B sulphate, neomycin sulphate, zinc bacitracin and their combinations with Escherichia coli suspended in buffer plus glucose medium.

Flow microcalorimetric assays for polymyxin B sulphate and neomycin sulphate have been developed using Escherichia coli as the test organism, suspended in a glucose plus buffer medium. These assays have a better reproducibility (relative standard deviations 3.2 and 2.0%, respectively), and require a shorter time (1 h including time required for preparation of the calorimeter) than do conventional microbiological assays, but are not as sensitive. It is suggested that a screening programme might produce a small group of more suitable (i.e. more sensitive) test organisms, which could be used to develop rapid and reproducible flow microcalorimetric assays for a wide range of antibiotics by the procedure described. The effect of combinations of polymyxin B sulphate, neomycin sulphate and zinc bacitracin (the antibiotic components of the commercial preparation Trisep, ICI, Macclesfield, UK) on the power output of cells suspended in glucose plus buffer medium is also reported. In defined combinations, the effects of neomycin sulphate appeared to be exerted before those of polymyxin B sulphate.

Bacitracin↗
PubMed2006

Analysis of neomycin using an improved liquid chromatographic method combined with pulsed electrochemical detection.

An isocratic liquid chromatographic method with pulsed electrochemical detection is described for the determination of neomycin in the presence of its impurities. The mobile phase is composed of an aqueous solution containing 35 g/l of sodium sulphate, 1 g/l of sodium 1-octanesulfonate, 14 ml/l of tetrahydrofuran (THF) and 50 ml/l of 0.2 M phosphate buffer pH 3.0. Sodium hydroxide was added post column to enhance the detection. An investigation of different reversed-phase columns indicated that the Discovery (C18 5 microm, 250 mm x 4.6 mm I.D.) column was the most suitable. The proposed method shows high efficiency, allowing the separation of the main component neomycin B from neomycin C and 15 other impurities. A central composite design was used to assess the robustness of the method. The method showed good selectivity, repeatability, linearity and sensitivity. This method was applied to analyse commercial samples.

Anti-Bacterial Agents↗
PubMed2004

Determination of neomycin by LC-tandem mass spectrometry using hydrophilic interaction chromatography.

A specific, and automated method was developed to quantitate neomycin in human serum. Samples were prepared with an automated solid phase extraction (SPE). The hydrophilic interaction chromatography (HILIC) was used for additional sample cleanup and baseline separation. The analyte neomycin was detected with electrospray ionisation tandem mass spectrometry (ESI-MS-MS). Using a volume of 500 microl biological sample the lower limit of quantification was 100 ng/ml. The described HILIC-MS-MS method is suitable for clinical and pharmcokinetical investigations of neomycin.

Chromatography, Liquid↗
PubMed2004

Development of a liquid chromatographic method for ear drops containing neomycin sulphate, polymyxin B sulphate and dexamethasone sodium phosphate.

Two liquid chromatographic methods were developed to analyse ear drops containing neomycin sulphate, polymyxin B sulphate and dexamethasone sodium phosphate. This formulation will be described in the Belgian National Formulary. Since neomycin, an aminoglycoside antibiotic, has no UV chromophore and pre or post column derivatization is complicated, pulsed electrochemical detection on a gold electrode was chosen to determine neomycin. Polymyxin B sulphate and dexamethasone sodium phosphate do have a UV chromophore. So, a single LC method with UV detection was developed for the determination of polymyxin B sulphate and dexamethasone sodium phosphate. The sample pretreatment is simply done by diluting the formulation with water. For each method, the influence of the different chromatographic parameters on the separation, the interference of other active compounds and excipients, the repeatability and the linearity were investigated. Finally, the content of the actives in the formulation was studied at 0, 2, 4, 6, and 8 weeks.

Chemistry, Pharmaceutical↗
PubMed1980

Neomycin absorption following Clagett procedure for postpneumonectomy empyema.

Following a Clagett stage II procedure, significant amounts of neomycin are absorbed when concentrations of 0.25% neomycin (8.9 micrograms milliliter) are used. If higher concentrations are employed, the neomycin can achieve toxic levels (40 micrograms per milliliter), with associated renal toxicity and respiratory suppression. The peel of the empyema cavity does not prevent absorption of drugs. Therefore, when drugs are inserted into an empyema cavity, due care must be exerted to prevent drug toxicity.

Absorption↗
PubMed1985

The quantitative determination of neomycin sulphate by a diffusion technique on agar plates by the method of the European Pharmacopoeia, 2nd edition--evaluation of precision and reproducibility of the method.

The medium recommended by the European Pharmacopoeia (EP), 2nd edition, for the microbiological determination of neomycin by the agar diffusion method was tested and compared with the medium recommended by the EP, 1st edition. The tests were carried out in different laboratories. The medium recommended by the EP, 2nd edition, gave greater precision and reproducibility than the previous medium. The possibility of using a reference standard of almost pure neomycin B for both the determination of framycetin and neomycin was evaluated. The results demonstrated that the medium recommended by the EP, 2nd edition, gave better precision and reproducibility. Difficulty in achieving valid assays was practically the same with both media.

Bacillus subtilis↗
PubMed1996

The antibiotic neomycin abolishes directional selectivity in rabbit retinal ganglion cells.

1. Extracellular recordings from ON/OFF directionally selective ganglion cells in superfused rabbit retinas were made to study the effect of the aminoglycoside antibiotic, neomycin, on the responses of these cells to a moving light stimulus. 2. Neomycin, at 480-800 microM, reversibly abolished the directional selectivity in these ganglion cells by bringing out a response to movement in one ("null") direction that was similar in magnitude to the response to movement in the reverse ("preferred") direction. 3. Gentamicin, streptomycin, and tobramycin were also able to abolish directional selectivity in these ganglion cells but only at concentrations greater than 1000 microM. 4. It is proposed that neomycin abolishes directional selectivity in rabbit retinal ganglion cells by blocking omega-conotoxin MVIIC-sensitive Ca2+ channels in the retina.

Animals↗
PubMed2003

Ion-association method for the colorimetric determination of neomycin sulphate in pure and dosage forms.

A simple, fairly rapid, sensitive and accurate method is described for the colorimetric determination of neomycin sulphate (NMS), based on the measurement of the absorbance of the extracted organic soluble ion-association complex formed between neomycin dictation and a bulky counter anion. Different chromotropic acid azo dyes were examined as counter ions. The effect of pH, the counter ion concentration, sequence of addition and solvents for extraction were also illustrated. The most suitable system is based on reagent VIII (pH 7.5) with chloroform as the extraction solvent. The use of other counter ions, in conjunction with their respective solvents, was found to be less sensitive. The neomycin-reagent VIII system exhibits negligible or no interference when used for the determination of up to 58 microgml(-1) of NMS in the presence of several drug excipiences. The method has been used for the determination of up to 58 microgml(-1) with a good recovery (99.8+/-1.5%), and the precision is supported by the low relative standard deviation </=1.35%. The sensitivity is discussed and the results are compared with the official method. The proposed method was applied successfully to the determination of NMS in pure and dosage forms, with a good precision and accuracy compared to the official one.

Anti-Bacterial Agents↗
PubMed1984

Binding to and antibacterial effect of ampicillin, neomycin and polymyxin B on human faeces.

Neomycin and polymyxin B, used during selective decontamination of the gastrointestinal tract, were studied for their effect on the human faecal flora in vitro. The selective effect was found to be associated with a relative insusceptibility of the obligate anaerobic flora as compared with the facultatively anaerobic Gram-negative rods (Escherichia coli). Both neomycin and polymyxin B were bound by human faeces, in contrast to ampicillin. The results may explain the selective effect of neomycin and polymyxin B on the human flora in vivo.

Ampicillin↗
PubMed2000

Patch testing with neomycin sulfate.

The recommended patch test concentration of neomycin sulfate is 20% in petrolatum applied occluded for 48 h (2 days [D]). In the current study, the efficiency of such a test is compared to results with other techniques using lower allergen dose than obtained by approximately 20 microl of the 20% substance. Efficiency of petrolatum and demineralized water as vehicles are compared. 16 neomycin-sulfate positive subjects were retested with serial doses ranging from 0.4 to 0.0085 mg/cm2 neomycin sulfate in cellulose printed on polyester squares and applied by both tapes and plastic foils. Additionally, tests were performed with the 20% petrolatum substance in Finn Chambers. Tests containing the 20% substance in petrolatum and in water were applied directly with transparent foils. Readings ranged from 3 to 264 h (11D) following applications. Results show that foil applications of a polyester square dose, that is 7% of the dose obtained with the 20% substance, distinguished between perfusion of subjects who were visually positive and not with any test in the study. With the same test technique and visual assessments, 2 subjects were false-negative but developed doubtful test responses with the Finn Chambers.

Dermatitis, Allergic Contact↗
PubMed2005

The neomycin biosynthetic gene cluster of Streptomyces fradiae NCIMB 8233: characterisation of an aminotransferase involved in the formation of 2-deoxystreptamine.

The biosynthetic gene cluster of the 2-deoxystreptamine (DOS)-containing aminoglycoside antibiotic neomycin has been cloned for the first time by screening of a cosmid library of Streptomyces fradiae NCIMB 8233. Sequence analysis has identified 21 putative open reading frames (ORFs) in the neomycin gene cluster (neo) with significant protein sequence similarity to gene products involved in the biosynthesis of other DOS-containing aminoglycosides, namely butirosin (btr), gentamycin (gnt), tobramycin (tbm) and kanamycin (kan). Located at the 5'-end of the neo gene cluster is the previously-characterised neomycin phosphotransferase gene (apH). Three genes unique to the neo and btr clusters have been revealed by comparison of the neo cluster to btr, gnt, tbm and kan clusters. This suggests that these three genes may be involved in the transfer of a ribose moiety to the DOS ring during the antibiotic biosynthesis. The product of the neo-6 gene is characterised here as the L-glutamine : 2-deoxy-scyllo-inosose aminotransferase responsible for the first transamination in DOS biosynthesis, which supports the assignment of the gene cluster.

Amination↗
PubMed1989

Kinetics of cell-free activation of neutrophil NADPH oxidase. Effects of neomycin and guanine nucleotides.

The effects of neomycin, fluoride and the non-hydrolysable guanine nucleotide analogue GTP gamma S on the kinetics of cell-free activation of NADPH oxidase in membranes of resting human neutrophils were investigated. Arachidonate-mediated activation of the oxidase followed a first-order reaction course (kobs. = 0.39 min-1 at 26 degrees C). In the presence of NaF during the activation process, activity was enhanced while the activation rate was slightly reduced (kobs. = 0.25 min-1 at 26 degrees C). Neomycin blocked activation (half-maximal effect at 25 microM) without affecting rates of superoxide release by preactivated enzyme in vitro or in vivo. In spite of reduced specific activity neither the first-order rate constant of the activation nor the Km of the oxidase were altered by neomycin. Oxidase activated in the presence of GTP gamma S exhibited increased specific activity and unchanged Km; the course of the reaction deviated from first-order kinetics. Kinetic evidence is presented for two separate activation reactions: a GTP gamma S-independent, basal, first-order process and a GTP gamma S-dependent sigmoid activation process. The results are compatible with the existence in neutrophil membranes of two separate pools of dormant oxidase. An alternative scheme of the formation of two active forms of NADPH oxidase is also presented.

Enzyme Activation↗