(n.) One of a series of anhydrides of an amido type, analogous to the lactones, as oxindol.
Example Sentences:
(1) An antagonism is unlikely when ciprofloxacin is combined with one of the beta-lactams studied or with tobramycin.
(2) Their sensitivity to aminoglycoside antibiotics, beta-lactams, tetracyclines, chloramphenicol, colistin, and ofloxacin was tested.
(3) Cefuzoname seems to be among the middle ranks of beta-lactam agents as far as penetration rate is concerned; however, when its potent antibacterial activity and broad spectrum are taken into account, the concentrations in CSF in patients with meningitis seem worth examining.
(4) Key therapeutic questions are whether beta-lactams can safely replace aminoglycosides for the treatment of gram-negative pneumonia, and whether monotherapy or aminoglycoside and beta-lactam combination antibiotic treatment is superior.
(5) A novel screening procedure led to isolation of the structurally unique, bacterially produced, monocyclic beta-lactam antibiotics early in 1979.
(6) Unlike most other beta-lactam antibiotics, imipenem does not show cross-resistance in the presence of intrinsic resistance.
(7) Owing to its broad spectrum of action (covering both gram-positive and gram-negative microorganisms and anaerobes) and its consistently strong molar action, mezlocillin is well suited as a beta-lactam combination component for intensive care patients.
(8) The addition of chloramphenicol to amino acid-deprived cultures of relA+ strains of Escherichia coli which were treated with beta-lactam antibiotics, D-cycloserine, or moenomycin resulted in lysis.
(9) 7, 578--581 (1975)] and show some resemblance to the effects of beta-lactams on the biosynthesis of Escherichia coli peptidoglycan.
(10) The hypoprothrombinemia in vitamin K-deficient female rats was caused by beta-lactam antibiotics with N-methyltetrazolethiol, thiadiazolethiol and methyl-thiadiazolethiol as the 3'-position substituent of the cephem nucleus.
(11) As the combination of two beta-lactams is sometimes antagonist, we studied the action of amoxicillin, clavulanic acid alone and in combination on H. influenzae beta-lactamase producer by kinetic turbidimetry and time-kill curve.
(12) In addition, there was evidence of opening of the beta-lactam ring to form cephalosporoic acid when the methyl ester of cefazolin was studied in human plasma and in the presence of penicillinase.
(13) Both ester and beta-lactam degradations of alpha-esters of carbenicillin disodium, carbenicillin indanyl sodium, and carbenicillin phenyl sodium in aqueous solution at 35 degrees and at 0.5 ionic strength were investigated.
(14) Paradoxical response to bactericidal activity of beta-lactams was abolished by incubation of the inoculum with 2 x MIC before exposure to higher antibiotic concentrations.
(15) Results showed that resistance to imipenem may be related to loss or modifications in hydrophobicity of an outer membrane protein of about 46 Kdal; other modifications concerned hydrophobicity of the porin OMP F and, in one strain, the LPS complex appears to be responsible for resistance to other beta-lactam antibiotics together in combination with the production of beta-lactamases.
(16) The emergence of multi-beta-lactam resistance is a limiting factor in treating invasive Pseudomonas infections with newer cephalosporins.
(17) The resulting patterns of MICs of NFLX, beta-lactams, aminoglycosides, and chloramphenicol and the observed increased accumulation of NFLX were consistent with the occurrence of the nfxB type mutation in these clinical isolates.
(18) None of the resistant variants thereby selected showed cross resistance to other beta-lactam antibiotics or aminoglycosides.
(19) A new PBP fraction (PBP2') having a molecular weight of 78,000 and low binding affinities for various beta-lactam antibiotics was found in MRSA exclusively.
(20) Newer beta-lactam antibiotics with high levels of activity against gram-negative aerobic bacilli (including Pseudomonas aeruginosa) such as cefoperazone, ceftazidime, imipenem, and aztreonam may be suitable for monotherapy of gram-negative pneumonia.
Lactone
Definition:
(n.) One of a series of organic compounds, regarded as anhydrides of certain hydroxy acids. In general, they are colorless liquids, having a weak aromatic odor. They are so called because the typical lactone is derived from lactic acid.
Example Sentences:
(1) These compounds were tentatively identified as two epimers at C-23 of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestano-26,23-lactone, which were probably artifacts formed from the corresponding tetrahydroxycholestanoic acids during the procedures for extraction after hydrolysis.
(2) Second, both lovastatin and simvastatin are administered as prodrugs in their lactone forms.
(3) The method involves the selective joining of two synthetic fragments, namely residues 1-65 of the apopeptide with Met65 replaced by homoserine lactone and residues 66-104 of the protein in the presence of fragment 1-25 of the native heme-containing peptide.
(4) Two new isomeric delta-lactones 2 and 3 have been isolated from the marine fungus Helicascus kanaloanus (ATCC 18591).
(5) Our data do not support the possibility of hydrogen bonding between the 16 beta-hydroxyl of gitoxigenin and the lactone ring, previously suggested to account for the decreased activity of gitoxigenin vis à vis digitoxigenin, but, rather, suggest that the decreased activity may be due to an intramolecular hydrogen bond between the hydroxyls on C-14 and C-16 and an unusual D-ring conformation which combine to alter the carbonyl oxygen of the lactone ring away from the putative active position.
(6) Status epilepticus was provoked in 10 rats by embedding coriaria lactone particle into the left cerebral motor cortex.
(7) Preliminary results indicate that chloride is eliminated during subsequent lactonization of the 2,3-dichloro-cis,cis-muconate, followed by hydrolysis to form 5-chloromaleylacetic acid.
(8) This ester, on standing, gradually formed the corresponding lactone.
(9) Studies were made on the ultraviolet difference-spectra of glucoamylase from Rhizopus niveus [EC 3.2.1.3] specifically produced by the substrate maltose and the inhibitors, glucose, glucono-1: 5-lactone (gluconolactone), methyl beta-D-glucoside, cellubiose, and cyclohexa-, and cyclohepta-amyloses.
(10) Pharmacokinetics of digitoxin (DGT) and its derivative hydrogenated at the unsaturated lactone ring have been studied using the 3H-labelled compounds in cats.
(11) The enzyme hydrolyzes aldonate lactones, such as D-galactono-gamma-lactone and L-mannono-gamma-lactone, stereospecifically.
(12) Since furanoses in the envelope form are analogous (in some ways) to half-chair or sofa conformations and since lactones with six-membered rings probably have half-chair or sofa conformations, the results indicate that beta-galactosidase probably destabilizes its substrate into a planar conformation of some type and that the galactose in the transition state may, therefore, also be quite planar.
(13) An unusual change in absorbance from 300 to 310-320 nm, obtained only with the valienamine-derived inhibitors or when D-glucono-1,5-lactone and maltose are combined, is concluded to arise when subsite 2 is occupied in a transition-state-type of complex.
(14) These studies showed that neither the strained trans-fused alpha-methylene lactone 12 nor the hydroxy-alpha-methylene lactones 5 and 6 reacted with cysteine with rates comparable to elephantopin.
(15) Relative to that of glucagon, biological activity and affinity of [des-Asn-28,Thr-29](homoserine lactone-27)-glucagon, prepared by CNBr treatment of glucagon, were reduced equally by 40- to 50-fold.
(16) These data indicate that PGF2alpha, 1-15 lactone decreases menstrual cycle lengths in non-pregnant rhesus monkeys.
(17) The metabolic pathway from 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] to 1 alpha,25-dihydroxyvitamin D3-26,23-lactone includes the formation of 1 alpha,23,25-26-tetrahydroxyvitamin D3 [1 alpha,23,25,26-(OH)4D3].
(18) The macrocyclic lactone ring is necessary for antibiotic activity.
(19) The lactones were treated with benzyl mercaptide anion to form 4-(benzylthio)butyric acid, which, on treatment with trifluoroacetic acid, cyclized to yield thiololactones.
(20) Thapsigargin is a potent skin irritating sesquiterpene lactone isolated from the roots of Thapsia garganica L. (Apiaceae).