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At least 1,099 records · Page 61Linked to original sources
PubMed1997

Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature.

Bacteria↗
PubMed1963

SMALL-CELL SEGREGANTS FROM A POSSIBLY HOMOZYGOUS DIPLOID STRAIN OF ESCHERICHIA COLI.

Ogg, James E. (Colorado State University, Fort Collins) and Ronald D. Humphrey. Small-cell segregants from a possibly homozygous diploid strain of Escherichia coli. J. Bacteriol. 85:801-807. 1963.-Evidence was presented to show that a homozygous possibly diploid strain of Escherichia coli, when grown in a chemically defined medium under the conditions described in this report, will yield small-cell segregants that have haploid characteristics. The segregants have one-half as much deoxyribonucleic acid per cell as the diploid, give exponential survival curves when exposed to X rays, and have fermentative characteristics similar to the original haploid parent strain of the homozygous diploid strain. No detectable changes in surface antigens were associated with the segregation phenomenon. The haploidlike segregants can be converted to the diploid radiation-resistant state by growing them in the presence of camphor vapors.

Colorado↗
PubMed1976

Doping control in Japan. An automated extraction procedure for the doping test.

Horse racing in Japan consists of two systems, the National (10 racecourses) and the Regional public racing (32 racecourses) having about 2,500 racing meetings in total per year. Urine or saliva samples for dope testing are collected by the officials from thw winner, second and third, and transported to the laboratory in a frozen state. In 1975, 76, 117 samples were analyzed by this laboratory. The laboratory provides the following four methods of analysis, which are variously combined by request. (1) Method for detection of drugs extracted by chloroform from alkalinized sample. (2) Methods for detection of camphor and its derivatives. (3) Method for detection of barbiturates. (4) Method for detection of ethanol. These methods consist of screening, mainly by thin layer chromatography and confirmatory tests using ultra violet spectrophotometry, gas chromatography and mass spectrometry combined with gas chromatography. In the screening test of doping drugs, alkalinized samples are extracted with chloroform. In order to automate the extraction procedure, the authors contrived a new automatic extractor. They also devised a means of pH adjustment of horse urine by using buffer solution and an efficient mechanism of evaporation of organic solvent. Analytical data obtained by the automatic extractor are presented in this paper. In 1972, we started research work to automate the extraction procedure in method (1) above, and the Automatic Extractor has been in use in routine work since last July. One hundred and twnety samples per hour are extracted automatically by three automatic extractors. The analytical data using this apparatus is presented below.

Animals↗
PubMed1981

Sequential cold-sensitive mutations in Aspergillus fumigatus. II. Analysis by the parasexual cycle.

From Aspergillus fumigatus I-21 (ATCC 32722), which grows at temperatures from 12 to 50 degrees C, three multistep, independently derived, cold-sensitive mutants unable to grow at 37 degrees C or below (Cs-37) were obtained by sequential exposure to ethylmethane sulfonate (strain AT2) or N-methyl-N'-nitro-N-nitrosoguanidine (AT1 and AT3). These mutants and ON5, a five-step Cs-37 mutant, were marked by mutations affecting spore color and nutritional requirements and crossed in four combinations by classical parasexual means. The heterokaryons demonstrated partial complementation with respect to auxotrophic requirements (suboptimal growth on minimal medium) and cold sensitivity (growth at 37 degrees C but not at 25 degrees C). Most presumed diploids, formed by exposure of the heterokaryons to d-camphor vapors, showed complete complementation but were unstable, as demonstrated by variations in spore sizes and markedly different ratios of segregant classes derived from different clones. Analysis of the segregants of the diploids or aneuploids, induced by Benomyl, indicated that multiple genes were responsible for cold sensitivity in each Cs-37 mutant, since segregants with various levels of cold sensitivity were obtained. The higher than predicted frequency of reversion to temperatures two or more steps back in the sequence of cold sensitivity mutations suggested that these genes or their products interacted. No Cs-37 segregant yielding a consistently lower frequency of revertants than the original mutants was obtained.

Aspergillus fumigatus↗
PubMed1999

Enantioselectivity of odor perception in squirrel monkeys and humans.

With use of a conditioning paradigm, the ability of six squirrel monkeys to distinguish between 10 pairs of enantiomers, i.e., odorants that are identical except for chirality, was investigated. As a group, the animals were only able to discriminate between the optical isomers of alpha-pinene, carvone, limonene, and fenchone, whereas they failed to distinguish between the (+) and (-) forms of beta-citronellol, menthol, rose oxide, 2-butanol, alpha-terpineol, and camphor. With use of a triple forced-choice procedure, 10 human subjects were tested for their ability to discriminate between the same enantiomeric odor pairs in parallel and, with the exception of fenchone, showed a very similar pattern of performance compared with the squirrel monkeys. These findings support the assumption that human and nonhuman primates may share common principles of odor quality perception. Furthermore, the results suggest that, in both species, enantioselective molecular odor receptors may only exist for some, but not all volatile enantiomers and thus that chiral recognition of odorants is not a general phenomenon, but may be restricted to some substances.

Adult↗
PubMed1989

Patterns of intracellular potentials in salamander mitral/tufted cells in response to odor stimulation.

1. Changes in membrane potential and temporal patterns of spikes were analyzed in 30 output cells in the salamander olfactory bulb in response to stimulation with 1-s pulses of the odorants isoamyl acetate, cineole, and camphor. The odor responses were more complex than responses to electrical stimulation of the olfactory nerve or olfactory tracts, with which they were compared. Most began with hyperpolarization and contained prolonged hyperpolarizing and depolarizing potentials that appeared to be compound postsynaptic potentials. These potentials were related to periods of spike inhibition and excitation. The temporal patterns of the responses resembled S-type (for suppression) and E-type (for excitation) patterns described previously in extracellular-unit studies. 2. In single cells, graded but nonmonotonic changes in the responses were observed with increases in the odor concentration from 10(-3) to 10(-1) vapor-phase saturation. Abrupt changes from one category of temporal response pattern to another were generally not observed in response to different concentrations of a single odorant but were frequently observed when the stimulus was changed from one odorant to another. 3. In S-type patterns, the first event was always membrane hyperpolarization and spike inhibition, regardless of the odor concentration. At all concentrations, simple S-type responses were observed in which a single period of hyperpolarization and inhibition lasted several seconds. At moderate to high concentrations, complex S-type responses were observed in which a period of excitation followed an initial period of hyperpolarization and inhibition. In these responses, spikes were often elicited near the termination of the odor pulse, occasionally as early as 300-400 ms after pulse onset. A prolonged period of inhibition followed the period of excitation. 4. In E-type patterns, the first event depended on the odor concentration. At all concentrations, complex responses were observed in which a period of excitation occurred with short latency, followed by a period of inhibition. At low to moderate concentrations, a brief initial period of hyperpolarization preceded the excitation. This initial period of hyperpolarization was always shorter than those in complex S-type responses to equivalent concentrations. However, the range of spike latencies overlapped that of S-type responses to high concentrations. With increasing odor concentration, spike latencies in the E-type responses decreased relative to the onset and peak of the initial hyperpolarization. At high concentrations. spikes were frequently elicited preceding a single period of hyperpolarization and inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1998

Photoallergic contact dermatitis due to combined UVB (4-methylbenzylidene camphor/octyl methoxycinnamate) and UVA (benzophenone-3/butyl methoxydibenzoylmethane) absorber sensitization.

In a 71-year-old male Caucasian patient with persistent eczema on light-exposed skin, photocontact allergy was demonstrated to the UV filter substances 4-methylbenzylidene camphor (UVB), octyl methoxycinnamate (UVB), benzophenone-3 (UVA) and butyl methoxydibenzoylmethane (UVA) present in sunscreen products used by the patient over several years. A significantly reduced UVB sensitivity of 25 mJ/cm2 in this patient (normal minimal erythema dose in our laboratory = 70-130 mJ/cm2) was considered an early indication of a persistent light reaction. Topical anti-inflammatory treatment over 2 weeks together with consequent application of a sunscreen containing Mexoryl SX/titanium dioxide led to complete remission. Taking into account the widespread use of the above UV filter substances not only in sun protection products, but also in cosmetics such as antiaging lotions and day care products, the possible risk of allergy to these chemicals has to be taken seriously. The substitution of known photocontact sensitizers in UV filters by photostable compounds and detailed product information are the basis of preventive strategies.

Aged↗
PubMedDate not supplied

Conditioning of body temperature and natural killer cell activity with arecoline, a muscarinic cholinergic agonist.

Arecoline, a muscarinic cholinergic agonist, was found to depress body temperature and elevate the activity of preactivated natural killer (NK) cells. To demonstrate that the unconditioned responses produced by arecoline were mediated through central nervous system pathways, we used the drug as an unconditioned stimulus. By pairing camphor odor (conditioned stimulus) with arecoline (unconditioned stimulus), it was possible to simultaneously condition both a decrease in body temperature and augmentation of NK cell activity. The observations suggest that although both the modulation of body temperature and NK cell activities are integrated at the level of the hypothalamus, these pathways of regulation can be differentiated.

Animals↗
PubMed2006

Comparison of essential oils from three plants for enhancement of antimicrobial activity of nitrofurantoin against enterobacteria.

BACKGROUND: Piperitone from plant essential oils enhancesbactericidal activities of nitrofurantoin and furazolidone against bacteria from the family Enterobacteriaceae. In this study, the essential oils of spearmint (Mentha spicata L.), dill (Anethum graveolens L.) and peppermint (Mentha piperita L.)were screened for augmentation of nitrofurantoin activity and the most active components were determined. METHOD: The effects of essential oils and their components on the bactericidal activity of nitrofurantoin against Enterobacter cloacae were studied using disk-diffusion and agar-dilution methods. The composition of essential oils was studied using gas chromatography-mass spectrometry. RESULTS: M. spicata and A. graveolens oils exhibited the highest effects. Gas chromatography-mass spectrometry analysis showed that the oils of these two plants contained 40.12 and 20.32% carvone, respectively. Pure carvone and piperitone equally increased the bactericidal activity of nitrofurantoin. Other ingredients of essential oils, including camphor, limonene and menthone, were less effective.

Anethum graveolens↗
PubMedDate not supplied

Transplants of olfactory mucosa in the anterior chamber of the eye: morphology, electrophysiology and biochemistry.

The olfactory mucosa from neonatal rats was transplanted into the anterior chamber of the eye. By 6-8 weeks after transplantation, morphological analysis showed the presence of olfactory sensory neurons in the grafts. The summated receptor potentials evoked by n-amyl acetate and camphor had the peak amplitude of about three times less and the duration of response of about 8-10 times more than those from normal olfactory epithelium. 6 h after beta-[3H]-alanine administration into the anterior chamber, more than 70% of the radioactivity was present in the carnosine fraction. This indicates that carnosine synthetase is present in the grafts. The presented data suggest that the grafts contain mature olfactory sensory neurons.

Animals↗
PubMed1997

Current management of the neonatal abstinence syndrome: a critical analysis of the evidence.

OBJECTIVE: To systematically and critically analyse and summarise the published evidence for the rational choice of pharmacologic treatment of the neonatal abstinence syndrome (NAS), a frequently observed condition in neonates born to mothers who are dependent on physically addicting drugs. DESIGN: Studies comparing different pharmacological agents for the treatment of NAS were identified utilising MEDLINE and additionally the references cited in pertinent articles. The identified studies were critically analysed regarding their study designs and outcome measures. The reported data for the comparative efficacy of the drugs were summarised and evaluated. RESULTS: Fourteen studies were identified, most of them comparing treatment of NAS with phenobarbital, paregoric or diazepam. However, none of these studies was conducted in a double-blind fashion. Frequently, treatment allocations were not properly randomised. Prenatal drug exposure varied and was often not sufficiently verified. Outcome measures and their evaluations differed widely. Due to the different study objectives and flaws in study design, a combined analysis of the published data in the form of a meta-analysis was not deemed possible. When attempting to compare efficacy, diazepam appears to be less efficacious in treating NAS than phenobarbital or paregoric. The relative efficacy of paregoric and phenobarbital appears to depend upon the antenatal exposure of the neonate and on the outcome measure of the study. Only two studies evaluate the efficacy of pure opioids, none of them in direct comparison to paregoric. It remains questionable whether paregoric, which contains the central stimulant camphor and a large amount of alcohol, should be the opioid of choice for the treatment of NAS. CONCLUSION: Most published studies were conducted prior to the development of clinical epidemiology and modern study design and thus yielded only very limited comparative data on the benefits of different treatment protocols. There is very little evidence regarding the efficacy of different pharmacological therapy regimens to treat NAS. More studies are required to produce the evidence needed to allow a rational choice between treatment modalities of NAS and thus to ensure optimal care of the neonates suffering from this condition.

Analgesics, Opioid↗
PubMed2003

Nano-octopus: a new form of branching carbon nanofiber.

A new multibranched octopus-type structure of carbon nanofibers is synthesized from a natural precursor, camphor, by a thermal chemical vapor deposition technique. An alloy of Cu:Ni catalyst is prepared by electrochemically coating nickel on a copper sheet, with nickel sulfate as an electrolyte, and heating that nickel-coated copper sheet to a higher temperature. Deposition of carbon on these substrates leads to the formation of a branched nanostructure in the temperature range of 923 K to 1023 K. The fiber diameter increases from 30 nm to 250 nm with increasing pyrolysis temperature. Detailed morphology and the internal structure of these fibers are studied by scanning and transmission electron microscopy.

Copper↗
PubMed2005

Application of carbon nanomaterial as a microwave absorber.

Microwave absorption (8 GHz to 12 GHz) studies have been made with carbon nanomaterials for the first time. Carbon nanomaterials are synthesized by the pyrolysis of camphor. It is observed that film of carbon prepared under certain synthetic condition, can absorb microwave of either some specific wavelengths e.g., 9.5 GHz and 11.5 GHz or full range from 8-12 GHz to the extent of 20 dB depending upon their preparation condition. Carbon nanobeads seems to absorb the microwave in the range of 8-12 GHz.

Carbon↗
PubMed2005

Y-junction multibranched carbon nanofibers.

Multibranched carbon nanofiber (CNF) is produced by a thermal chemical vapor deposition method using camphor as precursor. Nickel and cobalt catalyst was deposited on silicon substrate by e-beam evaporation and used as substrate for the growth of carbon nanomaterials. Branched carbon nanofibers were grown on the nickel thin film at 900 degrees C, whereas spherical carbon beads formed on the cobalt thin film. These fibers followed base growth mechanism devoid of any catalyst particle at the tip of fibers.

Crystallization↗
PubMedDate not supplied

Selection of test chemicals for the ECVAM international validation study on in vitro embryotoxicity tests. European Centre for the Validation of Alternative Methods.

The European Centre for the Validation of Alternative Methods (ECVAM) has sponsored a large international prevalidation and validation study of three embryotoxicity tests, involving embryonic stem cells, limb bud micromass cultures, and post-implantation whole-embryo cultures. The main objective of the study was to assess the performance of these in vitro tests in discriminating between non-embryotoxic, weakly embryotoxic and strongly embryotoxic compounds. An initial part of the study was to select 20 test substances for the formal validation trial, conducted under blind conditions. A database of in vivo and in vitro developmental toxicity test results was complied on 310 chemicals that had been used in previous validation studies, or suggested for such use, or that had good quality "segment II"-type in vivo data, or for which there were human data. From this database, a shortlist of about 30 candidates was constructed. Because the ECVAM study would not include metabolic activation, chemicals known to require activation for their developmental effects were excluded as candidates, although some known stable metabolites were included. Attempts were made: to include substances of diverse mechanism; to avoid overemphasis on pharmaceuticals; to avoid biologically inert substances as non-embryotoxicants; and to make the list different from those used previously. The candidates were of three categories: Class 3, strongly embryotoxic, was defined as developmentally toxic in all species tested, inducing multiple developmental effects, and with a high A/D ratio. Class 1, non-embryotoxic, was defined as not developmentally toxic at maternally toxic exposures, but which may show some minor embryo/fetal toxicity, which cannot be separated from maternal toxicity. Class 2, weakly embryotoxic, were chemicals of intermediate activity. From this candidate list, chemicals of known receptor (androgen, oestrogen, glucocorticoid, aryl hydrocarbon) mechanisms were excluded, on the basis that simple tests for such activity are already available. In addition, chemicals not freely available were excluded, and an emphasis on human data was applied. The final list of 20 chemicals was: Class 3--6-aminonicotinamide, 5-bromo- 2'-deoxyuridine, hydroxyurea, methylmercury chloride, methotrexate, all-trans-retinoic acid; Class 2--boric acid, dimethadione, lithium chloride, methoxyacetic acid, valproic acid (VPA), 2-propyl-4-pentynoic acid (4-yn-VPA), salicylic acid sodium salt; and Class 1--acrylamide, D-(+)-camphor, dimethyl phthalate, diphenhydramine hydrochloride, 2-ethyl-4- methylpentanoic acid (isobutyl-ethyl-VPA), Penicillin G sodium salt, saccharin sodium hydrate.

Animal Testing Alternatives↗
PubMedDate not supplied

Topical nonsteroidal antiinflammatory drugs for acute soft tissue injuries.

The empirical evidence supporting the use of topical NSAIDs in acute soft tissue injuries is weak. However, patient ratings of improvement consistently favor NSAID treatment over placebo. Although it is very difficult to differentiate the placebo effect from the natural course of improvement in these patients, the overall impression given by these studies is that of superior efficacy of topical NSAIDs over placebo. The study by Akermark and Forsskahl suggests that indomethacin applied topically is as effective as therapeutic doses of oral indomethacin. Further studies need to be conducted to generalize this conclusion to other NSAIDs. Studies comparing the relative efficacy of topical NSAIDs with counterirritants available over-the-counter (e.g., menthol, camphor, methylsalicylate) also would be useful.

Administration, Oral↗
PubMed2006

In vitro antibacterial activity of some plant essential oils.

BACKGROUND: To evaluate the antibacterial activity of 21 plant essential oils against six bacterial species. METHODS: The selected essential oils were screened against four gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris) and two gram-positive bacteria Bacillus subtilis and Staphylococcus aureus at four different concentrations (1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The MIC of the active essential oils were tested using two fold agar dilution method at concentrations ranging from 0.2 to 25.6 mg/ml. RESULTS: Out of 21 essential oils tested, 19 oils showed antibacterial activity against one or more strains. Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. CONCLUSION: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents.

Anti-Bacterial Agents↗
PubMed2005

Licorice: a possible anti-inflammatory and anti-ulcer drug.

The purpose of this investigation was to study the anti-inflammatory activities of both glycerrhitinic acid (GA) and the aqueous licorice extract (ALE) in comparison with diclofenac sodium (DS) (10 mg/kg), using the carrageenan-induced paw edema model in male albino rats. In addition, the anti-ulcer activities of ALE, famotidine (FT), and a combination of ALE and FT using indomethacin-induced ulceration technique in rat stomach were investigated. Conventional DS tablets containing GA, as well as DS chewable tablets containing either GA or ALE with different tastes were prepared. Also, rapidly disintegrating FT tablets were prepared using direct compression and camphor sublimation methods. ALE or GA produced significant anti-inflammatory activity similar to DS, and when taken concomitantly, there is no possible antagonism. The anti-ulcer activity of licorice was found to be similar to that of FT in indomethacin-induced ulceration technique in rat stomach. Combination therapy of both FT and licorice showed higher anti-ulcer activity than either of them alone. Generally, tablets containing the crosslinked sodium carboxymethyl cellulose (AcDisol) showed more rapidly disintegrating effect than those including Sodium starch glycolate (Primojel). The oral disintegration was very rapid for all the tested formulations. Also, the amount of FT absorbed from the oral cavity was nearly 9 from 10 mg theoretically present in each formula. It could be concluded that both GA and ALE have anti-inflammatory activity comparable with DS. It may be recommended to add ALE to either FT or diclofinac for more effective anti-inflammatory or anti-ulcer formulations, respectively.

Animals↗