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PubMed1987

Decrease in oligodendrocyte carbonic anhydrase activity preceding myelin degeneration in cuprizone induced demyelination.

Both immunohistochemical and biochemical evidence is presented to show for the first time that carbonic anhydrase II (CA II) activity falls in the brain of mice in cuprizone (bis(cyclohexanone)oxalyldihydrazone) induced demyelination well before demyelination develops. This fall began during the first week, whereas the first signs of myelin degeneration induced by cuprizone did not appear until 3 weeks and demyelination in the superior cerebellar peduncle in the mouse took 6-8 weeks to develop. The findings suggest that oligodendrocyte CA II activity is essential either for the survival of oligodendrocytes or for the maintenance of central myelin.

Animals↗
PubMed1990

Hyperthermic and anorectic effects of oxazolidines derived from L-ephedrine in rats.

Oxazolidines synthesized from (-) ephedrine have been proposed as potential pro-drugs, but no pharmacological data on these compounds has been yet reported. In this study, four such compounds are tested in rats for ephedrine-like activity using the hyperthermia and anorexia models. The compounds were synthesized by reaction of (-) ephedrine with salicylaldehyde, acetone, cyclohexanone, and benzaldehyde, respectively. The results showed that all of the compounds decreased food intake significantly, but only the acetone and the salicylaldehyde derivatives caused a significant elevation of body temperature. All of the compounds were less effective than (-) ephedrine in the anorexia model. The acetone and salicylaldehyde derivatives showed similar potency to (-) ephedrine in the hyperthermia model.

Animals↗
PubMed1982

Effect of odor quality and intensity on conditioned odor aversion learning in the rat.

Odor quality and intensity were varied to test the ability of rats to associate odor with an induced illness. Rats were allowed 10 minutes access to water on each of nine days; deodorized air was directed towards each rat's nose while drinking at familiarization and recovery sessions (days 1-5 and 7-8, respectively) and odorized air at treatment and test sessions (days 6 and 9, respectively). Each rat was injected with LiCl following its drinking period on day 6. The difference between the amount of water consumed on day 6 and day 9 gave a measure of the conditioned aversion. Only mild or no aversion occurred with odors of n-butyric acid, benzylamine, cyclohexanone, and n-butanol. Strong conditioned aversions were obtained to odors of triethylamine, 1,4-cineole, and isoamyl acetate, and the degree of aversion increased linearly with the log of odor concentration. The effect of odor quality, intensity and presentation method, and the role of the different chemoreceptor systems in the acquisition of odor aversions are discussed.

Animals↗
PubMed1990

Rat fetuses respond to chemical stimuli in gas phase.

Fetuses exhibit behavioral responses to intraoral infusions of chemical solutions presented in liquid phase, including an increase in overall activity and the production of a species-typical action pattern, facial wiping. A series of experiments were conducted in which chemical compounds with strong olfactory characteristics--citral and cyclohexanone--were presented in gas phase to rat fetuses on day 20 of gestation. Fetuses exhibited similar behavioral responses to stimuli presented in liquid and gas phases, suggesting a common basis for the processing of prenatal chemosensory information. Chemosensory stimuli in gas phase are sufficient to elicit both behavioral activation and a stereotypic action pattern of the rat fetus, patterns that anticipate postnatal olfactory-directed behavior. These results suggest that prenatal chemosensory experience, which normally occurs in an aqueous medium, may be relevant to the development of postnatal behavior that is directed by airborne olfactory cues.

Animals↗
PubMed1983

Concentration-dependent behavioral changes in mice following short-term inhalation exposure to various industrial solvents.

Mice were exposed during a 4-hr period to various concentrations of 13 aliphatic or aromatic solvents which affect primarily the central nervous system (CNS). The test compounds were benzyl chloride, butyl alcohol, chlorobenzene, cyclohexanone, 1,2-dichloroethylene, diisobutyl ketone, isopropyl acetate, methyl ethyl ketone, styrene, tetrachloroethylene, 1,1,1-trichloroethane, toluene, and ortho-xylene. After exposure, measurements were made to see whether these neurotoxicants would decrease the immobility developed in a "behavioral despair" swimming test. Each chemical was shown to reduce the total duration of immobility measured over a 3-min period in a concentration-related manner. The systematic determination of the atmospheric concentrations responsible for a 50% decrease in immobility (ID50) permitted classification of the solvents in terms of their relative potencies. The possibility of using such experimental data as tentative guidelines for setting safe levels of work exposure to the neurotoxicants was suggested, considering the existence of quantitative relationships between the ID50 values and the current occupational standards.

Animals↗
PubMed1987

Prediction of ocular irritation by corneal pachymetry.

Corneal pachymetry performed 3 days after application of a variety of test materials to the rabbit eye was found to be predictive of the eye irritation classification determined by observing the ocular response for 21 days. The test materials included NaOH, methanol, isopropanol, acetone, cyclohexanone, hexane and a shampoo. A 0.1-ml sample of the test material was placed in the conjunctival sac in the left eye of each rabbit. Both the left and the right eye of each rabbit were evaluated for irritation and corneal thickness for up to 21 days using a slit-lamp biomicroscope with a pachymeter attachment. On day 3 of observation the mean corneal thickness ratios (treated/control eye) were predictive of the duration of corneal cloudiness (correlation coefficient = 0.86). In addition, these ratios were predictive of the eye irritation classification as determined by a 21-day test (correlation coefficient = 0.98). Corneal pachymetry for determining eye irritation classification is presented as an alternative to the current 21-day test. It is more objective and requires a shorter observation period. Therefore, this method should lessen the cost of eye irritation testing and decrease the duration of discomfort that may occur among the test animals. The greater objectivity may also reduce the intra- and interlaboratory variation and the number of rabbits required for each testing.

Animals↗
PubMed1983

Toxic activity of seventeen industrial solvents and halogenated compounds on human lymphocytes cultured in vitro.

Seventeen chemicals (solvents, insecticides and intermediates in the production of textiles and resins) were tested in a short-term in vitro system with human lymphocytes to determine their toxic action. The parameters studied were the tritiated thymidine uptake and cell viability in cultures grown with or without a rat liver metabolizing system (S-9 mix). Data obtained showed that 1,3-dichlorobenzene, 1,2-dichlorobenzene, hexane, 1,2-diiodoethane, 1,4-dichlorobenzene, tetrachloroethylene, 2,3-dibromopropanol, chloromethyl methyl ether, 1,2- and 1,3-dibromopropane, in order, exerted the more toxic effects; ethyl acetate, cyclohexane, cyclohexanone and benzene showed lower toxic activity. The chemicals lost their toxic power in the presence of the metabolizing system with the exception of 1,2- and 1,3-dichlorobenzene which maintained in some degree their toxicity even in the presence of the S-9 mix. Only chloromethyl methyl ether elicited unscheduled DNA synthesis acting as DNA damaging agent.

Adult↗
PubMed1995

Discovery of a novel tetrahydroacridine acetylcholinesterase inhibitor through an indexed combinatorial library.

BACKGROUND: Methods for the rapid and efficient preparation of drug candidates through combinatorial chemistry are of increasing interest. We have previously reported an indexed combinatorial library method that allows both the preparation and testing of compounds in solution. We set out to apply this method to develop more effective analogs of the known, marketed drug tacrine, an acetylcholinesterase inhibitor. RESULTS: A one-step condensation of cyclohexanones with cyanoanilines to generate tetrahydroacridine pools was developed. The resulting library of (formally) 72 tetrahydroacridines was screened against acetylcholinesterase, and a compound 10-fold more potent than tacrine, 7-nitrotacrine, was discovered. Its increased potency could be readily explained by examining the known structure of the complex of acetylcholinesterase with tetrahydroacridine. CONCLUSIONS: In this work, we have provided a relatively rare example of carbon-carbon bond formation in a pool synthesis and have discovered a potentially useful acetylcholinesterase inhibitor.

Acridines↗
PubMed1999

Atypical glial cells in demyelinated and hypomyelinated mouse brains.

Bis-cyclohexanone oxalyldihydrazone (cuprizone) was administered to young adult mice in order to investigate the hypothesis that the differentiation of oligodendrocyte progenitors or precursors, or of immature oligodendrocytes, might be interrupted during cuprizone intoxication. Vibratome sections were prepared from brains from control mice, mice that were fed cuprizone for 27 days and mice that were fed cuprizone for 25 days, followed by normal diet for 2 days, and the sections were immunostained with monoclonal antibodies: MAbO4, which is directed against galactocerebroside sulfate (sulfatide); and RMAb, which is directed against galactocerebroside (GC). Process-bearing RMAb+/O4- cells were abundant in the brains of mice that had consumed cuprizone for 27 days, and the numbers of O4-positive cells were subnormal. Two days after refeeding the normal diet the RMAb+/O4- structures were less abundant and O4-positive cells more numerous. Moreover, the numbers of O4-positive cells were only approximately 20% of normal in the brains of hypomyelinating jimpy mutant mice, while the numbers of RMAb-positive cells were approximately 80% of normal, and the processes of the latter were associated with axons. It is suggested that RMAb+/O4- cells in the affected brains may be process-bearing oligodendrocyte precursors containing unsulfated GC or a toxic galactolipid.

Animals↗
PubMed2000

Evidence for covalent binding between copper ions and cyclodextrin cavity: a vibrational circular dichroism study.

Vibrational absorption and circular dichroism (VCD) spectra were obtained for parent cyclodextrins, hydroxyl deuterated alpha-cyclodextrin, cyclodextrin-copper complexes, and for the cyclodextrin inclusion complexes with Methyl Orange, methyloxirane, 1-propanol, and substituted cyclohexanones, in the solution phase. Changes in the VCD spectra, reflecting perturbations of cyclodextrin cavity, were found in the case of an inclusion complex with Methyl Orange, but for the remaining inclusion complexes measurable changes in VCD were not found. Significant changes observed in the VCD spectra of cyclodextrin-copper complexes suggest that the covalent binding of copper ions to the hydroxyl groups of cyclodextrin is involved.

1-Propanol↗
PubMed1975

Specific detection of volatile metabolites in urines of normal subjects and patients with diabetes mellitus using computerized mass fragmentography.

Volatile urinary components are analyzed by a combination of gas chromatography, mass spectrometry and a data-acquisition system. Mass fragmentograms using the mass spectrometric data on magnetic tape are recorded for the primary aliphatic alcohols ethanol, n-propanol, isobutanol and isopentanol and the ketones 4-hepatonone and cyclohexanone. The mass fragmentograms are used as selective profiles to facilitate recognition of abnormalities in the urinary components in cases of diabetes mellitus.

1-Propanol↗
PubMed1982

[Affinity chromatography of NAD(P)+ dehydrogenases dependent on the concentration of NAD(P)+ bound to ketones or aldehydes].

The use of general ligands such as NAD(P)+ for affinity chromatography of dehydrogenase requires elution with pulses of oxidized or reduced cofactor at suitable concentrations. This method of elution can involve considerable effort before ideal eluent conditions are evolved. We report on a new method of immobilized NAD(P)+ modifications which increases the selectivity of the phase and may be of rather wide application. The immobilized NAD(P)+ is modified by addition of a ketone or an aldehyde substrate of the dehydrogenase which must be purified and becomes a very specific ligand of that dehydrogenase. The adduct of immobilized NAD+ and sodium pyruvate absorbs specifically the lactate dehydrogenase, whereas the adduct of immobilized NAD+ and cyclohexanone adsorbs specifically the horse liver alcohol dehydrogenase. Absorbed dehydrogenases are eluted with NaCl gradients.

Aldehydes↗
PubMed2000

Orbital cortex neuronal responses during an odor-based conditioned associative task in rats.

Neuronal activity in the rat orbital cortex during discrimination of various odors [five volatile organic compounds (acetophenone, isoamyl acetate, cyclohexanone, p-cymene and 1,8-cineole), and food- and cosmetic-related odorants (black pepper, cheese, rose and perfume)] and other conditioned sensory stimuli (tones, light and air puff) was recorded and compared with behavioral responses to the same odors (black pepper, cheese, rose and perfume). In a neurophysiological study, the rats were trained to lick a spout that protruded close to its mouth to obtain sucrose or intracranial self-stimulation reward after presentation of conditioned stimuli. Of 150 orbital cortex neurons recorded during the task, 65 responded to one or more types of sensory stimuli. Of these, 73.8% (48/65) responded during presentation of an odor. Although the mean breadth of responsiveness (entropy) of the olfactory neurons based on the responses to five volatile organic compounds and air (control) was rather high (0.795), these stimuli were well discriminated in an odor space resulting from multidimensional scaling using Pearson's correlation coefficients between the stimuli. In a behavioral study, a rat was housed in an equilateral octagonal cage, with free access to food and choice among eight levers, four of which elicited only water (no odor, controls), and four of which elicited both water and one of four odors (black pepper, cheese, rose or perfume). Lever presses for each odor and control were counted. Distributions of these five stimuli (four odors and air) in an odor space derived from the multidimensional scaling using Pearson's correlation coefficients based on behavioral responses were very similar to those based on neuronal responses to the same five stimuli. Furthermore, Pearson's correlation coefficients between the same five stimuli based on the neuronal responses and those based on behavioral responses were significantly correlated. The results demonstrated a pivotal role of the rat orbital cortex in olfactory sensory processing and suggest that the orbital cortex is important in the manifestation of various motivated behaviors of the animals, including odor-guided motivational behaviors (odor preference).

Animal Feed↗
PubMed1999

On the use of liquid chromatography with radio- and ultraviolet absorbance detection coupled to mass spectrometry for improved sensitivity and selectivity in determination of specific radioactivity of radiopharmaceuticals.

Pneumatically assisted electrospray mass spectrometry was evaluated as a complementary detection technique to UV absorbance, for determination of specific radioactivity of tracer molecules to be used in positron emission tomography. Tracers labelled with radionuclides having short half-lives can be synthesised with high specific radioactivity. The UV absorbance detection that is commonly used for the determination does not always have the sensitivity required for those analyses. In comparison, mass spectrometry gave improved detection limits in all but one (nicotine) of the 12 compounds studied. The magnitude of this improvement was more than 100-fold for the compounds ketamine (2-methylamino-2-(2-chloro-phenyl)cyclohexanone), SCH-23390 ((R)-(+)-7-chloro-8-hydroxy-1-methyl-1-phenyl-2,3,4,5-tetra-hydro-1H-3-b enzazepine) and N-methyl-piperidylbenzilate. These improved detection limits, specificity, plus the added certainty of product identity provided by mass spectral data demonstrated the value of the mass spectrometer as a complementary detector in the determination of specific radioactivity.

Chromatography, Liquid↗
PubMed2000

Structure elucidation of methylidene malonate 2.1.2 cyclic trimers with mass spectrometry, liquid chromatography and nuclear magnetic resonance investigations.

The anionic polymerization of methylidene malonate 2.1.2. is able to yield four different molecule types. The major product obtained at pH 5.5 corresponds to a trisubstituted cyclohexanone formed by a back-biting reaction. A mixture of four diastereoisomer couples due to the presence of three asymmetric carbon atoms was produced in the same proportion. These results were deduced from mass spectrometry (MS), liquid chromatography MS (LC-MS) and 1H nuclear magnetic resonance (NMR) investigations.

Chromatography, High Pressure Liquid↗
PubMed1998

Free radical formation during ketamine anesthesia in rats: a cautionary note.

Ketamine is a useful anesthetic agent with good analgesic properties; however, when ketamine was used to anesthetize rats for spin trapping studies of alcohol-induced free radicals, liver extracts contained a strong electron paramagnetic resonance (EPR) signal of a novel radical. The same EPR signal was observed in liver extracts when rats which had not received alcohol were anesthetized with ketamine. When ketamine was added to liver microsomes and NADPH, a nitroxide radical derived from ketamine could be detected in organic extracts. When the spin trapping agent POBN was also added, microsomes produced both a ketamine nitroxide radical and a spin adduct. Similar results were obtained during ketamine oxidation by hydrogen peroxide in a tungstate-catalyzed reaction, or in a Fenton reaction system. The data suggest that the secondary amine group of ketamine can be oxidized to a stable nitroxide which produces an EPR spectrum in the absence of a spin trapping agent. The POBN spin adduct detected may be from a carbon-centered radical in the cyclohexanone ring of ketamine. Because several types of radicals can be formed from ketamine, this agent may not be appropriate as an anesthetic for many types of in vivo spin trapping experiments.

Anesthesia, General↗
PubMed1999

N-terminal 4-imidazolidinone prodrugs of Leu-enkephalin: synthesis, chemical and enzymatic stability studies.

Four N-terminal 4-imidazolidinone prodrugs of Leu-enkephalin are prepared and characterized. Their enzymatic and chemical stability are assessed using high-performance liquid chromatography. The prodrug derivatives are shown to degrade stoichiometrically to Leu-enkephalin in phosphate buffer [t1/2 (0.05 M phosphate buffer without KCl): acetone prodrug (II) 930 min; cyclopentanone prodrug (III): 216 min; cyclohexanone prodrug (IV): 432 min; 4-methylcyclohexanone prodrug (V): 792 min]. Furthermore, the prodrugs are shown to afford global stabilization of the Leu-enkephalin molecule towards the enzymes, aminopeptidase N and angiotensin converting enzyme, primarily responsible for degradation of Leu-enkephalin at the blood-brain barrier and in plasma. Therefore, the 4-imidazolidinones, being metabolic stable and bioreversible, may be suitable prodrug candidates for delivery of Leu-enkephalin to important target areas such as the brain, if given intravenously.

Blood-Brain Barrier↗
PubMed1997

The synthesis of (R)-(+)-lipoic acid using a monooxygenase-catalysed biotransformation as the key step.

2-(2-Acetoxyethyl)cyclohexanone (4) was converted into the lactone (-)-(5) regio- and enantioselectively using 2-oxo-delta 3-4,5,5-trimethylcyclopentenyl acetyl-CoA monooxygenase, an NADPH-dependent Baeyer-Villiger monooxygenase from camphor grown Pseudomonas putida NCIMB 10007. The lactone (-)-(5) was converted into (R)-(+)-lipoic acid in six steps. In contrast cyclopentanone monooxygenase, an NADPH-dependent Baeyer-Villiger monooxygenase from cyclopentanol-grown Pseudomonas sp. NCIMB 9872 selectively oxidized the (S)-enantiomer of the ketone (4) giving better access to optically enriched, naturally occurring lipoic acid.

Biotransformation↗