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At least 685 records · Page 38Linked to original sources
PubMed1999

Comparison of Optisol-GS and neomycin-polymyxin B-gramicidin ophthalmic solution for corneal storage in the dog.

The objective of the research was to compare the efficacy of Optisol-GS (OGS, Bausch & Lomb Surgical, Irvine, CA, USA) with triple antibiotic ophthalmic solution (neomycin-polymyxin B-gramicidin, NPG; Bausch & Lomb, Tampa, FL, USA) in preserving the viability of corneal endothelial cells. The study subjects were thirty young to middle-aged dogs with no gross corneal pathology that had been euthanized by pentobarbital overdose for reasons unrelated to this project. Corneal tissues were harvested, analyzed, and randomly assigned to treatment groups: one of two media (OGS or NPG), and one of five storage times (1, 7, 14, 21, or 35 days). Six corneas were stored in each medium for each time period. Corneal endothelial cell viability was evaluated pre- and poststorage by vital staining (trypan blue and alizarin red S), and endothelial cell morphology was evaluated with scanning electron microscopy. Storage in NPG caused significant loss (100%) of endothelial cells after all storage times. OGS storage maintained a high level of endothelial cell viability up to 21 days (98.9% +/- 1.3% viability). A significant decrease in percentage viability was also found for OGS-stored corneas between 21 and 35 days, when endothelial cell viability decreased to 61.4% +/- 45.9%. The conclusions are that NPG storage at -20 degrees C is a very poor choice of media for corneal tissue banking if graft clarity is the goal. Storage in Optisol-GS at 4 degrees C for up to 21 days resulted in significantly higher percentages of viable endothelial cells. Optisol-GS storage should facilitate corneal preservation for canine keratoplasty patients.

Journal Article↗
PubMed2003

The Tat antagonist neomycin B hexa-arginine conjugate inhibits gp-120-induced death of human neuroblastoma cells.

Several patients with acquired immunodeficiency syndrome (AIDS) develop neurological complications, which are referred to as human immunodeficiency virus (HIV)-associated dementia (HAD). The HIV-1 coat glycoprotein gp-120 has been proposed as the major etiologic agent for neuronal loss reported postmortem in the brain of AIDS patients. Chemokine receptors may play a role in gp-120-triggered neurotoxicity, both in vitro and in vivo, thus being an intriguing target for developing therapeutic strategies aimed to prevent or reduce neuronal damage occurring during HIV infection. We have previously shown that human CHP100 neuroblastoma cells express CXCR4 and CCR5 chemokine receptors and that interaction between gp-120 and these receptors contributes to cytotoxicity elicited by the protein. Here, we examined the neuroprotective potential of neomycin B hexa-arginine conjugate (NeoR), a recently synthesized compound with anti-HIV activity. We found that gp-120-triggered death is significantly reduced by NeoR, and this protective effect seems related to the ability of NeoR to interact with CXCR4 receptors. The ability of NeoR to cross the blood-brain barrier, as demonstrated in mice by systemic administration of the fluorescein conjugate drug, makes this compound a powerful and attractive therapeutic agent.

Animals↗
PubMed1979

Susceptibility to butirosin and neomycin B in Bacillus circulans, the butirosin-producing organism.

Butirosin, an aminoglycoside antibiotic, is produced by Bacillus circulans B-3312. Experiments using recombined ribosomal and supernatant fractions from this strain and from B. megaterium KM have shown that the ribosome of both are sensitive to butirosin. The aminoglycoside 3'-phosphotransferase present in B. circulans modifies butirosin and neomycin in vitro but confers resistance only to the former in vivo. The phosphotransferase does not modifya detectable amount of extracellular butirosin while mediating resistance to the antibiotic. In vitro, however, the enzyme appears to protect against inhibition by butirosin by inactivating the bulk of the antibiotic in the system. An extrachromosomal element of unknown function has been detected in B. circulans.

Anti-Bacterial Agents↗
PubMed1997

Cre/loxP-mediated excision of a neomycin resistance expression unit from an integrated retroviral vector increases long terminal repeat-driven transcription in human hematopoietic cells.

Recombinant retroviruses are currently the most attractive vehicles for gene transfer into hematopoietic cells. Retroviral vectors often contain an easily selectable marker gene in addition to the gene of interest. However, the presence and selection for expression of the selectable gene often result in a significant reduction of the expression of the gene of interest in the transduced cells. In order to circumvent this problem, we have developed a Cre/loxP recombination system for specific excision of the selectable expression unit from integrated retroviruses. A retroviral vector, containing both a neomycin resistance expression unit flanked by loxP sites and granulocyte-macrophage colony-stimulating factor cDNA, was used to transduce the human hematopoietic K-562 cell line. Four transduced cell clones were then superinfected with a retrovirus containing a Cre recombinase expression unit. Molecular analyses of 30 doubly transduced subclones showed a strict correlation between cre expression and loxP-flanked selectable cassette excision, thus implying that Cre recombinase activity is very efficient in a retroviral context. Moreover, the excision of the selectable cassette results in a significant increase of granulocyte-macrophage colony-stimulating factor transcription driven by the retroviral promoter.

Animals↗
PubMed1990

A rapid immunoprecipitation assay for neomycin phosphotransferase II expression in transformed bacteria and plant tissues.

Anti-kanamycin antibodies produced in rabbits, following coupling of the antibiotic to bovine serum albumin, were used to immunoprecipitate radioactively labelled phosphorylated kanamycin from transformed bacterial or plant extracts in a novel assay system, for the detection of neomycin phosphotransferase II (NPTII) activity. Radioactive counts in the immunoprecipitated pellet give a semiquantitative measure of the kanamycin phosphorylation and hence the amount of NPTII activity. This assay is sensitive, uses very small amounts of radioactivity, and is very rapid, allowing many samples to be processed within a few hours. Immunoprecipitated counts from reactions with bacteria carrying a kanamycin resistance gene or from tobacco and Brassica napus plants transformed with NPTII gene-containing vectors were consistently higher than counts from nontransformed controls. Results obtained with this assay correlate well with those from the previously described gel overlay and dot-blot assays, but can be obtained in an appreciably shorter time frame.

Animals↗
PubMed1986

Deafness after treatment with ear drops containing neomycin, gramicidin and dexamethasone. A case report.

We describe a patient with a polyethylene tube to the middle ear who developed severe deafness and vertigo after treatment with ear drops where neomycin B was considered to be the most likely offending agent. High concentration of this antibiotic in the ear drops and access of the solution to the round window membrane in the absence of inflammatory edema and secretion may have been significant factors contributing to this serious side effect. Less ototoxic preparations should be used in patients with perforated tympanic membranes or grommets.

Deafness↗
PubMed1990

MYCIN and NEOMYCIN: two approaches to generating explanations in rule-based expert systems.

The prototypical rule-based expert system is MYCIN, a computer program developed in the 1970's to diagnose and recommend therapy for serious infections. MYCIN is able to explain its reasoning at any point in a consultation by listing the rules it has under consideration at that moment. However, when MYCIN's rules were used as the subject matter for a computerized infectious disease tutoring system, it became apparent that these rules contained implicit knowledge about how to perform diagnostic tasks and that this knowledge was inaccessible to the explanation system and, therefore, to students. This paper briefly describes NEOMYCIN, an expert system that makes this implicit knowledge explicit, and shows the effect that this reconfiguration of knowledge has on generating explanations.

Diagnosis, Computer-Assisted↗
PubMed1977

Antimicrobial agents--Part II. The aminoglycosides: streptomycin, kanamycin, gentamicin, tobramycin, amikacin, neomycin.

Aminoglycoside antibiotics are poorly absorbed from the gastrointestinal tract, do not penetrate well into the cerebrospinal fluid, are minimally bound to plasma proteins, and are rapidly excreted by the normal kidney. Neomycin is limited by its toxicity to irrigating and topical preparations or to oral medication for surgical bowel preparations or hepatic coma. Streptomycin has only a few specific indications, because newer agents are available that have broader spectrums of activity. Kanamycin is indicated in serious gram-negative infections in which Pseudomonas aeruginosa is not a likely causative agent. Gentamicin, tobramycin, and amikacin are effective against a broad spectrum of gram-negative organisms including P. aeruginosa. In general, both gentamicin and tobramycin are more active in vitro than amikacin on a weight basis; however, higher serum levels are achievable with amikacin than with the two others. Amikacin is probably the aminoglycoside of first choice when gentamicin resistance is strongly suspected.

Amikacin↗