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PubMed1992

[Protoplast fusion in Streptomyces fradiae strains producing neomycin and tylosin].

Interspecies fusion of protoplasts of the Streptomyces fradiae strains producing neomycin (an aminoglycoside antibiotic) and tylosin (a macrolide antibiotic) was performed with a view to isolate strains producing novel antibiotics. Fusion of the protoplasts of the neomycin- and tylosin-producing strains labelled by the resistance to monomycin and lincomycin, respectively, caused no formation of stable strains producing antibiotics differing in chromatographic mobility from the antibiotics produced by the initial strains. In fusion of the protoplasts of the unlabelled strains, heat-inactivated protoplasts of the active line of one strain (donor) and native protoplasts of the inactive line of the other strain (recipient) were used. When the neomycin-producing culture was used as a recipient the fusion led to formation of strain 195-34 producing antibiotics of the benzo(a)anthraquinone group. One of these antibiotics, i.e. antibiotic 34-I, proved to be a novel biologically active substance. After regeneration of the protoplasts of the initial strains, no stable strains producing antibiotics differing from neomycin and tylosin were isolated.

Drug Resistance, Microbial↗
PubMed1992

Bioactive polymers. 70. The kinetics of controlled release of neomycin in an alkaline medium.

Neomycin is coupled on xanthan--a polysaccharide of microbial biosynthesis produced by Xanthomona campestris--through ionic complexation. The kinetics of neomycin release, in vitro, at pH = 8.2 is studied. A release of neomycin, following a zero order kinetics, is observed, regardless of the eluent flow-rate. The neomycin-xanthan complex, protected by a cellulosic membrane, behaves like a monolithic-type device. Diffusion coefficients--increasing with increasing the eluent flow-rate--are also calculated.

Delayed-Action Preparations↗
PubMed1989

Development of neomycin-resistant WEHI-3B D+ murine cells as an in vivo model of acute nonlymphocytic leukemia.

pSV2 neomycin DNA was electroporated into exponentially growing WEHI-3B D+ cells, and clones containing integrated pSV2 neomycin DNA were selected by treatment with the antibiotic Geneticin. Southern analysis after Eco RI or Bam HI and Hind III digestion demonstrated that two clones, Y1 and Y2, stably incorporated a single copy of intact pSV2 neomycin DNA into different sites. Exposure of parental WEHI-3B D+ cells to retinoic acid, aclacinomycin A, or adriamycin resulted in their differentiation to mature granulocytic cells. Clone Y1 had growth kinetics and numbers of differentiated cells comparable to those of the parental line when exposed to these differentiation-inducing agents. Furthermore, this clone was leukemogenic in BALB/c mice. The disease presented as a moderate anemia, a peripheral blood granulocytosis, a shift in the differential to immature granulocytic forms, and a thrombocytopenia. Although there was no change in bone marrow cellularity, in situ hybridization to identify the presence of the neomycin resistance gene mRNA indicated infiltration of leukemia cells (up to 30%) into this tissue compartment. The observed hematological parameters were indicative of a late stage of disease resembling human acute nonlymphocytic leukemia. Clone Y1, therefore, would appear to be an in vivo model of acute nonlymphocytic leukemia that may be useful for the development of therapeutic strategies to more successfully treat these diseases. Because we have demonstrated that this line is capable of differentiation in vitro and can be stably carried in vivo, it would also be useful for the identification of therapeutic agents capable of initiating the differentiation of leukemia cells in situ.

Animals↗
PubMed1978

[Phosphate group donors for neomycin inactivation by resistant microorganism strains].

The substrate specificity of aminoglycoside phosphotransferases isolated from 3 strain of E. coli and purified was studied. All pure enzymes phosphorilated neomycin, paromomycin, lividomycin, neamine, ribostamycin, kanamycins A and B. Only ATP was the donor of the phosphate groups in these reactions, while in the non-purified extracts GTP but not UTP or CTP served as the donor of the phosphate group for inactivation of neomycin. The substrate specificity indicated that the above enzymes were aminoglycoside-3(1)-phosphotransferases. Inactivation of neomycin with the use of the phosphate group of phosphoenolpiruvate as the donor in the non-purified enzymatic preparations of the neomycin-resistant strains of E. coli and Pseudomonas was not observed.

Adenosine Triphosphate↗
PubMed1987

Nitrogen in fecal bacterial, fiber, and soluble fractions of patients with cirrhosis: effects of lactulose and lactulose plus neomycin.

To determine how lactulose and lactulose plus neomycin might alter nitrogen metabolism in the colon we investigated the effect of these agents on the distribution of nitrogen in the bacterial, soluble, and fiber fractions of stool. The alterations in fecal nitrogen excretion were additionally correlated with changes in total body urea synthesis and degradation rates. Six patients with stable cirrhosis received a control diet alone followed by the administration of lactulose (56 +/- 6 gm/day), and eight similar patients received lactulose alone (63 +/- 5 gm/day) followed by the addition of neomycin (4 gm/day). Their feces were partitioned into individual fractions by physical separation. Lactulose administration increased nitrogen excreted in the bacterial fraction by 165% (from 0.52 +/- 0.14 gm/day to 1.38 +/- 0.21 gm/day) and by 135% in the soluble fraction (from 0.58 +/- 0.08 gm/day to 1.36 +/- 0.23 gm/day). When lactulose was supplemented with neomycin, the nitrogen content of the bacterial fraction decreased by 28%. Lactulose caused a 23% reduction in the urea production rate that was mainly accounted for by increase in fecal nitrogen excretion. The addition of neomycin caused a further reduction in urea production that was explained by an inhibition of urea degradation. These results demonstrate that a major effect of lactulose was to augment the incorporation of nitrogen into fecal bacteria although nitrogen in the soluble fraction also increased. The additional nitrogen excreted in the fecal bacterial and soluble fractions caused a reduction in urea synthesis.

Aged↗
PubMed1986

The effect of neomycin on plasma alpha tocopherol levels in type II hyperlipoproteinemia.

Use of oral neomycin as a hypocholesterolemic agent was found to decrease plasma alpha tocopherol levels during a 9-month, randomized, crossover placebo-controlled clinical trial with controlled diet. Pooled data from each treatment sequence showed a placebo alpha-tocopherol level of 1,896 +/- 643 micrograms/dl, and a neomycin alpha-tocopherol concentration of 1,449 +/- 451 micrograms/dl (p less than .01). When all subjects were on neomycin simultaneously, the level increased to 1,665 +/- 614 micrograms/dl (p less than .05 from placebo). Normal plasma alpha-tocopherol ranges from 400-1,000 micrograms/dl. Neomycin treatment reduces but does not normalize elevated levels of alpha-tocopherol found in Type II hyperlipoproteinemia.

Cholesterol, LDL↗
PubMed1985

A prospective, randomized, double-blind study of 10% mannitol mechanical bowel preparation combined with oral neomycin and short-term, perioperative, intravenous Flagyl as prophylaxis in elective colorectal resections.

The effect of 1-day mechanical bowel preparation with 10% mannitol combined with oral neomycin and short-term perioperative intravenous Flagyl (group I) was studied in a prospective, randomized, double-blind study and was compared with oral neomycin and an intravenous placebo (Group II). Thirty-one patients were evaluated in group I (Flagyl), and there was a 0% septic complication rate. Thirty-seven patients were in the neomycin placebo group (group II), which had a septic complication rate of 22%. The difference between the two groups was statistically significant. No complications were observed from either the 10% mannitol solution or the intravenous Flagyl at either clinical, hematologic, or biochemical assessment. The study indicates that 1-day mechanical bowel preparation with 10% mannitol combined with oral neomycin and short-term, perioperative, intravenous Flagyl is a safe, effective, and inexpensive method for significantly reducing the septic complications of elective colorectal surgical resections.

Adolescent↗
PubMed1968

Experimental cholelithiasis in the rabbit induced by cholestanol feeding: effect of neomycin treatment on bile composition and gallstone formation.

Fed cholestanol is converted by the rabbit to 5alpha-bile acids which coprecipitate with the normally occurring 5beta-bile acids to form gallstones composed of calcium and sodium glycoallodeoxycholate and glycodeoxycholate. The present study shows that oral administration of large doses of neomycin prevents gallstone formation in the cholestanol-fed rabbit and reduces the elevated concentration of allodeoxycholic acid in bile, with a reciprocal increase in allocholic acid concentration. The reduction in the concentration of allodeoxycholic acid and in the incidence of gallstones is proportional to the dose of neomycin; at a concentration of allodeoxycholic acid below about 20% of total bile acids, gallstone formation does not occur. Neomycin probably exerts its action by modifying the anerobic intestinal flora which dehydroxylate allocholic acid to allodeoxycholic acid; if so, this suggests that both hepatic and bacterial transformations are essential steps in the pathogenesis of cholestanol-induced cholelithiasis. The bile of rabbits on a normal diet contains allodeoxycholic acid (5% of total bile acids). A similar decrease in allodeoxycholic acid concentration and reciprocal increase in allocholic acid concentration is observed when neomycin is administered to rabbits on a normal diet.

Animals↗
PubMed1982

Absorption of oral neomycin in premature infants with suspected necrotizing enterocolitis.

The oral absorption of neomycin was studied in 2 premature infants (32 weeks of gestation) with suspected necrotizing enterocolitis. 1 infant received 50 mg and the other 100 mg of neomycin sulfate/kg/day in 4 divided doses for approximately 7 days. Plasma neomycin levels were determined by a micro, sensitive and specific high-performance liquid chromatographic assay developed in our laboratory. Plasma levels as high as 2.9 and 4.5 micrograms/ml were observed in these 2 infants. A urinary recovery study for 1 infant revealed that at least 3.7% of the oral dose was absorbed. The significant and persistent plasma levels of neomycin in these patients suggest the need for extreme caution in using this potentially toxic antibiotic for prolonged treatment in neonates.

Chromatography, High Pressure Liquid↗
PubMed1980

Effects of neomycin on the waveform of auditory-evoked brain stem potentials in dogs.

Neomycin sulfate was administered intravenously to eight mixed-breed dogs at a dosage of 30 mg/kg/day for as long as 50 days. Auditory-evoked brain stem potentials (AEBP) were recorded from the dogs three times a week. The AEBP amplitudes and latencies from the eight treated and the eight control dogs were compared. All treated dogs eventually exhibited an isoelectric AEBP. The time required for the AEBP waveform loss to occur in the treated dogs varied between 22 and 50 days. The AEBP waveforms were still isoelectric when measured as long as 150 days after neomycin administration was stopped. The fact that AEBP did not return would tend to support the findings of others that the loss of the receptors in the inner ear, due to neomycin toxicity, is permanent. The results of this electrophysiologic study indicate that the organ of Corti (organum spirale) is the site of pathologic changes in the auditory system that result from neomycin treatment.

Animals↗
PubMed1994

Bioavailability of vitamin A in the rat following ingestion of neomycin sulfate or aluminium hydroxide.

The objective of the present paper was to study the interaction of Neomycin and aluminium hydroxide with vitamin A in terms of the effect of these drugs on the bioavailability of vitamin A in the rat. Bioavailability was determined on the basis of the effects of the drugs on growth and on the plasma and hepatic levels of the vitamin. Vitamin A deficient animals were used in assay 1 and normal animals in assay 2. In each assay the animals were divided into 3 groups: one received Neomycin sulfate (0.1% in the diet), the second received aluminium hydroxide (0.05% in the diet) and the third (control) received no drug. Each of these three groups was subdivided into two groups receiving two different concentrations of vitamin A palmitate. The bioavailability of vitamin A was estimated by the parallel line method from the concentration of vitamin A in the diet and in the liver of the animals. No significant differences in growth or plasma retinol levels were observed between the groups of animals studied in assays 1 and 2. Total vitamin A concentration in the liver of the animals which received Neomycin was lower (p < 0.05) than that observed in the controls. Neomycin reduced the bioavailability of vitamin A by 13.9% (maximum, 18.1% and minimum, 9.6%) in assay 1 and by 13.5% (maximum, 17.7% and minimum, 9.3%) in assay 2. Aluminium hydroxide at the level tested did not affect the bioavailability of vitamin A.

Aluminum Hydroxide↗
PubMed1993

Neomycin--a frequent contact allergen.

The incidence of allergic contact dermatitis from neomycin evaluated in relation to 1381 verified cases of allergic contact dermatitis showed a progressive increase (5.00, 7.69, 10.18%) over a three-year period (1990-1992). Sensitivity to neomycin was investigated with special reference to possible cross-reactions between neomycin and the allergens that are commonly used in the manufacture of cosmetic products. Contact sensitivity to neomycin was found to be present with the other diagnoses, such as atopic dermatitis, seborrhoeic dermatitis, hypostasic dermatitis and psoriasis vulgaris.

Adult↗
PubMed1993

[Treatment with neomycin and Na2EDTA for skin infections in rabbits caused by Staphylococcus aureus].

The rabbits were infected intradermally with a strain of S. aureus resistant to neomycin. They were treated with neomycin, Na2EDTA and by combination of these substances, which were applied as a cream with differing concentrations of these factors. Simultaneous application of neomycin and Na2EDTA for treatment of experimental staphylococcal infections caused in rabbits with a strain resistant to neomycin, resulted in acceleration of healing of pustular changes, when compared with results obtained in animals treated with these substances alone.

Administration, Topical↗
PubMed1995

An extended study: protective effects of nerve growth factor in neomycin-induced auditory neural degeneration.

Intracochlear survival of auditory neurons is thought to be a factor contributing to the success of cochlear implantations. Damage to the cochlear end-organ is frequently associated with loss of neurites in the osseous spiral lamina. The authors have previously reported a model for long-term intracochlear administration of pharmacologic agents using a technique and device analogous to a cochlear implant. These studies suggest that nerve growth factor (NGF) protects the auditory nerve from the immediate neurotoxic effects of neomycin. The intent of the present investigation is to determine whether NGF can protect auditory neural elements from neomycin-induced degeneration after several weeks have elapsed between the neomycin perfusion and the administration of NGF. Neomycin was infused over 24 hours through an indwelling, intracochlear cannula attached to a mini osmotic pump to unilaterally destroy the cochlear end-organ. The pump perfused the cochlea with artificial perilymph for 2 weeks. Then, the pump reservoirs were surgically replaced; the new reservoirs delivered either NGF or artificial perilymph for an additional 2 weeks. Spiral ganglion cell densities were measured along Rosenthal's canal in the basal, middle, and apical cochlear turns. This investigation revealed that NGF prevented auditory nerve degeneration over the 2-week period, when compared to controls, and that the protective effect was greatest in the neural elements closest to the source of NGF.

Animals↗
PubMed1976

[Absorption, distribution and the duration of retention of neomycin in the body of pregnant rabbits and their fetuses].

Neomycin was administered intramuscularly to rabbits in single doses of 50000 gamma/kg 24--25-day gravid rabbits were sacrificed 1.5-2-3-4-6-12-24 hours and 2-3-6 days after the drug administration. 3--4 rabbits were used in every experiment. The antibiotic concentration was determined with the agar-diffusion method. It was found that the drug was present in various bactericidal concentrations in all 55 organs, tissues and fluids of the rabbits and the fetus examined except the crystalline lens in the rabbits and the brain, liver and bile cyst of the fetus. In some material of the rabbits and their fetus, high levels of neomycin were detected during 6 days, i. e. up to the end of the experiment. The highest neomycin levels in the organs, tissues and fluids of the fetus were detected somewhat later than in those of the rabbits. However, their retention time was longer. It is necessary to forbear from using antibiotics, such as neomycin, monomycin and others, which retained for long periods of time in the organism.

Absorption↗
PubMed1999

Saccharide-RNA recognition in a complex formed between neomycin B and an RNA aptamer.

BACKGROUND: Aminoglycoside antibiotics can target RNA folds with micromolar affinity and inhibit biological processes ranging from protein biosynthesis to ribozyme action and viral replication. Specific features of aminoglycoside antibiotic-RNA recognition have been probed using chemical, biochemical, spectroscopic and computational approaches on both natural RNA targets and RNA aptamers identified through in vitro selection. Our previous studies on tobramycin-RNA aptamer complexes are extended to neomycin B bound to its selected RNA aptamer with 100 nM affinity. RESULTS: The neamine moiety (rings I and II) of neomycin B is sandwiched between the major groove floor of a 'zippered-up' G.U mismatch aligned segment and a looped-out purine base that flaps over the bound antibiotic. Specific intermolecular hydrogen bonds are observed between the charged amines of neomycin B and base mismatch edges and backbone phosphates. These interactions anchor 2-deoxystreptamine ring I and pyranose ring II within the RNA-binding pocket. CONCLUSIONS: The RNA aptamer complexes with tobramycin and neomycin B utilize common architectural principles to generate RNA-binding pockets for the bound aminoglycoside antibiotics. In each case, the 2-deoxystreptamine ring I and an attached pyranose ring are encapsulated within the major groove binding pocket, which is lined with mismatch pairs. The bound antibiotic within the pocket is capped over by a looped-out base and anchored in place through intermolecular hydrogen bonds involving charged amine groups of the antibiotic.

Anti-Bacterial Agents↗
PubMed2002

Displacement of Mn2+ from RNA by K+, Mg2+, neomycin B, and an arginine-rich peptide: indirect detection of nucleic acid/ligand interactions using phosphorus relaxation enhancement.

We have developed a novel method to study the interactions of nucleic acids with cationic species. The method, called phosphorus relaxation enhancement (PhoRE), uses (1)H-detected (31)P NMR of exogenous probe ions to monitor changes in the equilibrium between free Mn(2+) and Mn(2+) bound to the RNA. To demonstrate the technique, we describe the interactions of four RNA molecules with metal ions (K(+) and Mg(2+)), a small molecule drug (neomycin b), and a cationic peptide (RSG1.2). In each case, cationic ligand binding caused Mn(2+) to be displaced from the RNA. Free Mn(2+) was determined from its effect on the T(2) NMR relaxation rate of either phosphite (HPO(3)(2-)) or methyl phosphite (MeOPH, CH(3)OP(H)O(2-)). Using this method, the effects of [RNA] as low as 1 microM could be measured in 20 min of accumulation using a low field (200 MHz) instrument without pulsed field gradients. Cation association behavior was sequence and [RNA] dependent. At low [K(+)], Mn(2+) association with each of the RNAs decreased with increasing [K(+)] until approximately 40 mM, where saturation was reached. While saturating K(+) displaced all the bound Mn(2+) from a 31-nucleotide poly-uridine (U(31)), Mn(2+) remained bound to each of three hairpin-forming sequences (A-site, RRE1, and RRE2), even at 150 mM K(+). Bound Mn(2+) was displaced from each of the hairpins by Mg(2+), allowing determination of Mg(2+) dissociation constants (K(d,Mg)) ranging from 50 to 500 microM, depending on the RNA sequence and [K(+)]. Both neomycin b and RSG1.2 displaced Mn(2+) upon binding the hairpins. At [RNA] approximately 3 microM, RRE1 bound a single equivalent of RSG1.2, whereas neither RRE2 nor A-site bound the peptide. These behaviors were confirmed by fluorescence polarization using TAMRA-labeled peptide. At 2.7 microM RNA, the A-site hairpin bound a single neomycin b molecule. The selectivity of RSG1.2 binding was greatly diminished at higher [RNA]. Similarly, each hairpin bound multiple equivalents of neomycin at the higher [RNA]. These results demonstrate the utility of the PhoRE method for characterizing metal binding behaviors of nucleic acids and for studying RNA/ligand interactions.

Amino Acid Sequence↗
PubMed2001

Aminoglycoside binding displaces a divalent metal ion in a tRNA-neomycin B complex.

Aminoglycosides bind to RNA and interfere with its function, and it has been suggested that aminoglycoside binding to RNA displaces essential divalent metal ions. Here we demonstrate that addition of various aminoglycosides inhibited Pb2+-induced cleavage of yeast tRNA(Phe). Cocrystallization of yeast tRNA(Phe) and an aminoglycoside, neomycin B, resulted in crystals that diffracted to 2.6 A and the structure of the complex was solved by molecular replacement. The structure shows that the neomycin B binding site overlaps with known divalent metal ion binding sites in yeast tRNA(Phe), providing direct evidence for the hypothesis that aminoglycosides displace metal ions. Additionally, the neomycin B binding site overlaps with major determinants for Escherichia coli phenylalanyl-tRNA-synthetase. Here we present data demonstrating that addition of neomycin B inhibited aminoacylation of E. coli tRNA(Phe) in the mid microM range. Given that aminoglycoside and metal ion binding sites overlap, we discuss that aminoglycosides can be considered as 'metal mimics'.

Acylation↗