Neomycin. Medical search

Antibiotic complex produced by Streptomyces fradiae. It is composed of neomycins A, B, and C. It acts by inhibiting translation during protein synthesis.

A component of NEOMYCIN that is produced by Streptomyces fradiae. On hydrolysis it yields neamine and neobiosamine B. (From Merck Index, 11th ed)

A class of enzymes that inactivate aminocyclitol-aminoglycoside antibiotics (AMINOGLYCOSIDES) by regiospecific PHOSPHORYLATION of the 3' and/or 5' hydroxyl.

A broad-spectrum antimicrobial isolated from Streptomyces ribosifidicus.

Antibiotic complex produced by Streptomyces kanamyceticus from Japanese soil. Comprises 3 components: kanamycin A, the major component, and kanamycins B and C, the minor components.

Glycosylated compounds in which there is an amino substituent on the glycoside. Some of them are clinically important ANTIBIOTICS.

Substances that reduce the growth or reproduction of BACTERIA.

An oligosaccharide antibiotic produced by various STREPTOMYCES.

An antibiotic produced by the soil actinomycete Streptomyces griseus. It acts by inhibiting the initiation and elongation processes during protein synthesis.

The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).

A complex of closely related aminoglycosides obtained from MICROMONOSPORA purpurea and related species. They are broad-spectrum antibiotics, but may cause ear and kidney damage. They act to inhibit PROTEIN BIOSYNTHESIS.

A TETRACYCLINE analog isolated from the actinomycete STREPTOMYCES rimosus and used in a wide variety of clinical conditions.

Nonsusceptibility of bacteria to the antibiotic KANAMYCIN, which can bind to their 70S ribosomes and cause misreading of messenger RNA.

A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5)

Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)

A malabsorption syndrome that is associated with a blind loop in the upper SMALL INTESTINE that is characterized by the lack of peristaltic movement, stasis of INTESTINAL CONTENTS, and the overgrowth of BACTERIA. Such bacterial overgrowth interferes with BILE SALTS action, FATTY ACIDS processing, MICROVILLI integrity, and the ABSORPTION of nutrients such as VITAMIN B12 and FOLIC ACID.

Any tests done on exhaled air.

A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.

A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.

Pathological processes of the LIVER.

A subspecialty of internal medicine concerned with the study of the physiology and diseases of the digestive system and related structures (esophagus, liver, gallbladder, and pancreas).

A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p887)

Liver disease in which the normal microcirculation, the gross vascular anatomy, and the hepatic architecture have been variably destroyed and altered with fibrous septa surrounding regenerated or regenerating parenchymal nodules.

Elevated level of AMMONIA in the blood. It is a sign of defective CATABOLISM of AMINO ACIDS or ammonia to UREA.

The interactions between physician and patient.

An agency of the PUBLIC HEALTH SERVICE concerned with the overall planning, promoting, and administering of programs pertaining to maintaining standards of quality of foods, drugs, therapeutic devices, etc.

Use of plants or herbs to treat diseases or to alleviate pain.

Chinese herbal or plant extracts which are used as drugs to treat diseases or promote general well-being. The concept does not include synthesized compounds manufactured in China.

Prudent standard preventive measures to be taken by professional and other health personnel in contact with persons afflicted with a communicable disease, to avoid contracting the disease by contagion or infection. Precautions are especially applicable in the diagnosis and care of AIDS patients.

A mixture of polymyxins B1 and B2, obtained from Bacillus polymyxa strains. They are basic polypeptides of about eight amino acids and have cationic detergent action on cell membranes. Polymyxin B is used for infections with gram-negative organisms, but may be neurotoxic and nephrotoxic.

Basic lipopeptide antibiotic group obtained from Bacillus polymyxa. They affect the cell membrane by detergent action and may cause neuromuscular and kidney damage. At least eleven different members of the polymyxin group have been identified, each designated by a letter.

Semisolid preparations used topically for protective emollient effects or as a vehicle for local administration of medications. Ointment bases are various mixtures of fats, waxes, animal and plant oils and solid and liquid hydrocarbons.

Common name for FISHES belonging to the order Perciformes and occurring in three different families.

The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.

A glucocorticoid derivative used topically in the treatment of various skin disorders. It is usually employed as a cream, gel, lotion, or ointment. It has also been used topically in the treatment of inflammatory eye, ear, and nose disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p732)

Inflammation in which both the anterior and posterior segments of the uvea are involved and a specific focus is not apparent. It is often severe and extensive and a serious threat to vision. Causes include systemic diseases such as tuberculosis, sarcoidosis, and syphilis, as well as malignancies. The intermediate segment of the eye is not involved.

An extremely variable eczematous skin disease that is presumed to be a response to prolonged vigorous scratching, rubbing, or pinching to relieve intense pruritus. It varies in intensity, severity, course, and morphologic expression in different individuals. Neurodermatitis is believed by some to be psychogenic. The circumscribed or localized form is often referred to as lichen simplex chronicus.

Inflammation of the choroid as well as the retina and vitreous body. Some form of visual disturbance is usually present. The most important characteristics of posterior uveitis are vitreous opacities, choroiditis, and chorioretinitis.

Small containers or pellets of a solid drug implanted in the body to achieve sustained release of the drug.

A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.

Prodigious substrate specificity of AAC(6')-APH(2"), an aminoglycoside antibiotic resistance determinant in enterococci and staphylococci. (1/850)

BACKGROUND: High-level gentamicin resistance in enterococci and staphylococci is conferred by AAC(6')-APH(2"), an enzyme with 6'-N-acetyltransferase and 2"-O-phosphotransferase activities. The presence of this enzyme in pathogenic gram-positive bacteria prevents the successful use of gentamicin C and most other aminoglycosides as therapeutic agents. RESULTS: In an effort to understand the mechanism of aminoglycoside modification, we expressed AAC(6')-APH(2") in Bacillus subtilis. The purified enzyme is monomeric with a molecular mass of 57 kDa and displays both the expected aminoglycoside N-acetyltransferase and O-phosphotransferase activities. Structure-function analysis with various aminoglycosides substrates reveals an enzyme with broad specificity in both enzymatic activities, accounting for AAC(6')-APH(2")'s dramatic negative impact on clinical aminoglycoside therapy. Both lividomycin A and paromomycin, aminoglycosides lacking a 6'-amino group, were acetylated by AAC(6')-APH(2"). The infrared spectrum of the product of paromomycin acetylation yielded a signal consistent with O-acetylation. Mass spectral and nuclear magnetic resonance analysis of the products of neomycin phosphorylation indicated that phosphoryl transfer occurred primarily at the 3'-OH of the 6-aminohexose ring A, and that some diphosphorylated material was also present with phosphates at the 3'-OH and the 3"'-OH of ring D, both unprecedented observations for this enzyme. Furthermore, the phosphorylation site of lividomycin A was determined to be the 5"-OH of the pentose ring C. CONCLUSIONS: The bifunctional AAC(6')-APH(2") has the capacity to inactivate virtually all clinically important aminoglycosides through N- and O-acetylation and phosphorylation of hydroxyl groups. The extremely broad substrate specificity of this enzyme will impact on future development of aminoglycosides and presents a significant challenge for antibiotic design. (+info)

Position-dependent inhibition of class-switch recombination by PGK-neor cassettes inserted into the immunoglobulin heavy chain constant region locus. (2/850)

The Ig heavy chain (IgH) constant region (CH) genes are organized from 5' to 3' in the order Cmicro, Cdelta, Cgamma3, Cgamma1, Cgamma2b, Cgamma2a, Cepsilon, and Calpha. Expression of CH genes downstream of Cdelta involves class-switch recombination (CSR), a process that is targeted by germ-line transcription (GT) of the corresponding CH gene. Previously, we demonstrated that insertion of a PGK-neor cassette at two sites downstream of Calpha inhibits, in cultured B cells, GT of and CSR to a subset of CH genes (including Cgamma3, Cgamma2a, Cgamma2b, and Cepsilon) that lie as far as 120 kb upstream. Here we show that insertion of the PGK-neor cassette in place of sequences in the Igamma2b locus inhibits GT of and CSR to the upstream Cgamma3 gene, but has no major effect on the downstream Cgamma2a and Cepsilon genes. Moreover, replacement of the Cepsilon exons with a PGK-neor cassette in the opposite transcriptional orientation also inhibits, in culture, GT of and CSR to the upstream Cgamma3, Cgamma2b, and Cgamma2a genes. As with the PGK-neor insertions 3' of Calpha studied previously, the Cgamma1 and Calpha genes were less affected by these mutations both in culture and in mice, whereas the Cgamma2b gene appeared less affected in vivo. Our findings support the existence of a long-range 3' IgH regulatory region required for GT of and CSR to multiple CH genes and suggest that PGK-neor cassette insertion into the locus short circuits the ability of this region to facilitate GT of dependent CH genes upstream of the insertion. (+info)

The role of the pseudo-disaccharide neamine as an intermediate in the biosynthesis of neomycin. (3/850)

By using wild-type and deoxystreptamine-negative mutants of Streptomyces fradiae grown in media containing [6(-3)H]glucose or [U-14C]glucose, and by subsequent hydrolysis of the labelled neomycin produced, neamines labelled with 3H in both rings I and II, but with 14C in ring I only, were prepared. A mixture of these two forms of neamine was converted by deoxystreptamine-negative Streptomyces rimosus forma paromomycinus into neomycin (not paromomycin) with a 30% yield. The3H: 14C ratio in this neomycin was the same as the measured in neamine produced by hydrolysis of the neomycin, and in unused neamine reisolated from the incubation medium. The 3H:14C ratio in the neomycin was not affected by the presence of unlabelled deoxystreptamine during the incubation. The radioactivity in the neomycin was associated with rings I and II only. It is concluded that the added neamine is incorporated into antibiotic intact, without initial hydrolysis, and that the probable first step in the subunit assembly of neomycin is the formation of neamine. (+info)

A conserved sequence block in the murine and human TCR J alpha region: assessment of regulatory function in vivo. (4/850)

Temporal control of rearrangement at the TCR alpha/delta locus is crucial for development of the gamma delta and alpha beta T cell lineages. Because the TCR delta locus is embedded within the alpha locus, rearrangement of any V alpha-J alpha excises the delta locus, precluding expression of a functional gamma delta TCR. Approximately 100 kb spanning the C delta-C alpha region has been sequenced from both human and mouse, and comparison has revealed an unexpectedly high degree of conservation between the two. Of interest in terms of regulation, several highly conserved sequence blocks (> 90% over > 50 bp) were identified that did not correspond to known regulatory elements such as the TCR alpha and delta enhancers or to coding regions. One of these blocks lying between J alpha 4 and J alpha 3, which appears to be conserved in other vertebrates, has been shown to augment TCR alpha enhancer function in vitro and differentially bind factors from nuclear extracts. To further assess a plausible regulatory role for this element, we have created mice in which this conserved sequence block is either deleted or replaced with a neomycin resistance gene driven by the phosphoglycerate kinase promoter (pgk-neor). Deletion of this conserved sequence block in vivo did have a local effect on J alpha usage, echoing the in vitro data. However, its replacement with pgk-neor had a much more dramatic, long range effect, perhaps underscoring the importance of maintaining overall structure at this locus. (+info)

Integrin-regulated secretion of interleukin 4: A novel pathway of mechanotransduction in human articular chondrocytes. (5/850)

Chondrocyte function is regulated partly by mechanical stimulation. Optimal mechanical stimulation maintains articular cartilage integrity, whereas abnormal mechanical stimulation results in development and progression of osteoarthritis (OA). The responses of signal transduction pathways in human articular chondrocytes (HAC) to mechanical stimuli remain unclear. Previous work has shown the involvement of integrins and integrin-associated signaling pathways in activation of plasma membrane apamin-sensitive Ca2+-activated K+ channels that results in membrane hyperpolarization of HAC after 0. 33 Hz cyclical mechanical stimulation. To further investigate mechanotransduction pathways in HAC and show that the hyperpolarization response to mechanical stimulation is a result of an integrin-dependent release of a transferable secreted factor, we used this response. Neutralizing antibodies to interleukin 4 (IL-4) and IL-4 receptor alpha inhibit mechanically induced membrane hyperpolarization and anti-IL-4 antibodies neutralize the hyperpolarizing activity of medium from mechanically stimulated cells. Antibodies to interleukin 1beta (IL-1beta) and cytokine receptors, interleukin 1 receptor type I and the common gamma chain/CD132 (gamma) have no effect on me- chanically induced membrane hyperpolarization. Chondrocytes from IL-4 knockout mice fail to show a membrane hyperpolarization response to cyclical mechanical stimulation. Mechanically induced release of the chondroprotective cytokine IL-4 from HAC with subsequent autocrine/paracrine activity is likely to be an important regulatory pathway in the maintenance of articular cartilage structure and function. Finally, dysfunction of this pathway may be implicated in OA. (+info)

Improved reporter strain for monitoring Cre recombinase-mediated DNA excisions in mice. (6/850)

Effective use of conditional Cre recombinase-loxP gene modification requires Cre-expressing mouse strains with defined patterns of expression. To assess the in vivo functionality of Cre-expressing mice, we have engineered an improved reporter strain for monitoring Cre-mediated excisions. The beta-galactosidase-neomycin phosphotransferase fusion gene (betageo)-trapped ROSA26 locus was modified by gene targeting such that betageo is expressed only after Cre-mediated excision of loxP-flanked DNA sequences. betageo from the excised ROSA26 allele is expressed ubiquitously in embryos and adult mice. By mating the reporter strain with Cre-expressing transgenic mice, we have shown that the loxP-flanked ROSA26 allele is accessible to Cre during early embryogenesis, as well as in a specific hematopoietic lineage (T lymphocytes). This improved reporter strain should facilitate monitoring in vivo Cre-mediated excision events in a variety of experimental contexts. (+info)

Aluminum is a weak agonist for the calcium-sensing receptor. (7/850)

BACKGROUND: Aluminum (Al3+) has diverse biological effects mediated through activation of a putative extracellular cation-sensing receptor. A recently identified calcium-sensing receptor (CaSR), which has been identified in target tissues for Al3+, may transduce some of the biological effects of Al3+. METHODS: To test this possibility, we transfected human embryonic kidney 293 (HEK 293) cells with a cDNA encoding the rat CaSR and evaluated CaSR expression by Western blot analysis and function by measurement of intracellular calcium ([Ca2+]i) levels and inositol monophosphate (IP1) generation following stimulation with Al3+ and a panel of CaSR agonists. RESULTS: The CaSR protein was detected by immunoblot analysis in cells transfected with the CaSR cDNA but not in nontransfected HEK 293 cells. In addition, [Ca2+]i levels and IP1 generation were enhanced in a dose-dependent fashion by additions of the CaSR agonists calcium (Ca2+), magnesium (Mg2+), gadolinium (Gd3+), and neomycin only in cells transfected with CaSR. To determine if Al3+ activated CaSR, we stimulated cells transfected with rat CaSR with 10 microM to 1 mM concentrations of Al3+. Concentrations of Al3+ in the range of 10 microM to 100 microM had no effect on [Ca2+]i levels or IP1 generation. In contrast, 1 mM Al3+ induced small but significant increases in both parameters. Whereas Gd3+ antagonized calcium-mediated activation of CaSR, pretreatment with Al3+ failed to block subsequent activation of rat CaSR by Ca2+, suggesting a distinct mechanism of Al3+ action. CONCLUSION: Al3+ is not a potent agonist for CaSR. Because Al3+ affects a variety of target tissues at micromolar concentrations, it seems unlikely that CaSR mediates these cellular actions of Al3+. (+info)

The supporting-cell antigen: a receptor-like protein tyrosine phosphatase expressed in the sensory epithelia of the avian inner ear. (8/850)

After noise- or drug-induced hair-cell loss, the sensory epithelia of the avian inner ear can regenerate new hair cells. Few molecular markers are available for the supporting-cell precursors of the hair cells that regenerate, and little is known about the signaling mechanisms underlying this regenerative response. Hybridoma methodology was used to obtain a monoclonal antibody (mAb) that stains the apical surface of supporting cells in the sensory epithelia of the inner ear. The mAb recognizes the supporting-cell antigen (SCA), a protein that is also found on the apical surfaces of retinal Muller cells, renal tubule cells, and intestinal brush border cells. Expression screening and molecular cloning reveal that the SCA is a novel receptor-like protein tyrosine phosphatase (RPTP), sharing similarity with human density-enhanced phosphatase, an RPTP thought to have a role in the density-dependent arrest of cell growth. In response to hair-cell damage induced by noise in vivo or hair-cell loss caused by ototoxic drug treatment in vitro, some supporting cells show a dramatic decrease in SCA expression levels on their apical surface. This decrease occurs before supporting cells are known to first enter S-phase after trauma, indicating that it may be a primary rather than a secondary response to injury. These results indicate that the SCA is a signaling molecule that may influence the potential of nonsensory supporting cells to either proliferate or differentiate into hair cells. (+info)

2010). Neomycin Is Named Contact Allergen of the Year Archived 2015-04-22 at archive.today Sasseville, D (2010). "Neomycin". ... Neomycin (antibiotic) 2009 - Mixed dialkyl thiourea - Neoprene rubber is a common source. 2008 - Nickel 2007 - Fragrance 2006 ...

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