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At least 865 records · Page 48Linked to original sources
PubMed1991

Kallmann's syndrome and chemosensory evoked potentials.

Kallmann's syndrome is generally assessed by history and subjective tests of olfactory function. In this study three patients suffering from Kallmann's syndrome were investigated with more objective techniques, including the recording of chemosensory evoked potentials (CSEPs). After testing olfactory function by means of a simple odor identification test, anosmia was confirmed in only one patient, since the other two patients were able to distinguish between several odorants. However, investigations in which CSEPs were employed indicated that all three patients had complete loss of their olfaction as well as hypersensitivity of the trigeminal nerve. These findings prove the usefulness of CSEPs in clinical investigations of the sense of smell.

Adolescent↗
PubMed1993

Discriminating parts from the whole: determinants of odor mixture perception in squirrel monkeys, Saimiri sciureus.

In a task designed to simulate olfactory-guided foraging, the ability of squirrel monkeys to discriminate an artificial 12-component odorant from 3-, 6-, 9- or 11-component submixtures was investigated. A combination of factors was found to contribute to the animals' performance: 1. Discriminability generally decreased as the number of components in the submixture increased. 2. Submixtures did not contribute equally to mixture perception, and one component in particular (cineole) disproportionately influenced stimulus discriminability. 3. Interactive effects between submixtures resulted in marked deviations from the general pattern of discriminability. 4. Changes in the relative concentration of submixtures could also influence discriminability. 5. Finally, individual differences in responsiveness to particular stimuli were apparent. These findings demonstrate that the interaction between components in odor mixtures can be complex and that seemingly small changes in composition can strongly affect perception and thus potential signal function. It is therefore suggested that in future investigations of squirrel monkey semiochemistry, the method of systematically varying submixtures may be particularly useful in defining the contribution of components to a signal.

Adult↗
PubMed1988

Effects of topical anesthetics on tympanic membrane structure.

Topical application of a local anesthetic agent can induce adequate insensibility to pain, and therefore can avoid the use of general anesthesia or invasive infiltration techniques for myringotomy or the insertion of a tympanostomy tube. A comparative study was conducted on a guinea pig animal model to determine the effects of three agents on the structure of the tympanic membrane: 5% tetracaine base dissolved in dimethylsulfoxide (DMSO), pure DMSO, and Bonain's solution. Survival times ranged from 1 day to 3 months. Following removal from the animals, membranes were embedded in Spurr and cut in semithin sections. Signs of mild or severe external otitis were frequent; to avoid non-specific results, infected specimens were not evaluated. Bonain's solution caused loss of the epidermis and mucosal epithelium within 1 day of treatment. The connective tissue layers of the drum were severely hyperplastic after a survival time of 1 month. Tetracaine base in DMSO caused a loss of epithelium and mucosal cells in 3 days. Regeneration started within 7 days and a restitution to integrity was seen after 3 months in drums treated with tetracaine base or DMSO alone.

Administration, Topical↗
PubMed1988

Spatial variation in response to odorants on the rat olfactory epithelium.

We have measured the electro-olfactogram produced by four odorants, nicotine, i-pentyl acetate, i-pentanoic acid and cineole from twelve positions on an in vitro preparation of rat olfactory tissue. Each odorant shows a different pattern of response over the twelve positions which can be explained by differences in olfactory receptor populations between regions of the rat olfactory epithelium. The result for nicotine is further evidence that there are olfactory receptors which are stimulated by nicotine when it is presented as a vapour.

Action Potentials↗
PubMed1991

Discharge pattern analysis suggests existence of a low-threshold calcium channel in cold receptors.

The regular periodic activity patterns of mammalian cold receptors have been quantitatively studied. Analysis of the timing of either single impulses or impulse groups demonstrated that the periodic receptor process is maintained independently of impulse generation and continues to operate under conditions when afferent impulses are not initiated. These results imply that the underlying conductances must be operational at threshold potentials related to impulse generation. In addition to temperature, the periodic process is considerably sensitive to calcium, which affects mainly the probability of impulse generation during each cycle. Reduction of external calcium and application of calcium entry blockers with relative selectivity for low-threshold calcium channels are similarly effective in modulating cold receptor activity. The data imply the existence of a low-threshold calcium conductance at the sensory terminal.

Afferent Pathways↗
PubMed2000

Terpinen-4-ol, the main component of the essential oil of Melaleuca alternifolia (tea tree oil), suppresses inflammatory mediator production by activated human monocytes.

OBJECTIVE AND DESIGN: To evaluate potential antiinflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia. MATERIAL AND METHODS: The ability of tea tree oil to reduce the production in vitro of tumour necrosis factor-alpha (TNFalpha), interleukin (IL)-1beta, IL-8, IL-10 and prostaglandin E2 (PGE2) by lipopolysaccharide (LPS)-activated human peripheral blood monocytes was examined. RESULTS: Tea tree oil emulsified by sonication in a glass tube into culture medium containing 10% fetal calf serum (FCS) was toxic for monocytes at a concentration of 0.016% v/v. However, the water soluble components of tea tree oil at concentrations equivalent to 0.125% significantly suppressed LPS-induced production of TNFalpha, IL-1beta and IL-10 (by approximately 50%) and PGE2 (by approximately 30%) after 40 h. Gas chromatography/mass spectrometry identified terpinen-4-ol (42 %), a-terpineol (3 %) and 1,8-cineole (2%, respectively, of tea tree oil) as the water soluble components of tea tree oil. When these components were examined individually, only terpinen-4-ol suppressed the production after 40 h of TNFalpha, IL-1beta, IL-8, IL-10 and PGE2 by LPS-activated monocytes. CONCLUSION: The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

The water-soluble components of the essential oil of Melaleuca alternifolia (tea tree oil) suppress the production of superoxide by human monocytes, but not neutrophils, activated in vitro.

OBJECTIVE: To evaluate the regulatory properties of the essential oil of Melaleuca alternifolia (tea tree oil) on the production of oxygen derived reactive species by human peripheral blood leukocytes activated in vitro. MATERIALS AND METHODS: The ability of tea tree oil to reduce superoxide production by neutrophils and monocytes stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP), lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) was examined. RESULTS: The water-soluble fraction of tea tree oil had no significant effect on agonist-stimulated superoxide production by neutrophils, but significantly and dose-dependently suppressed agonist-stimulated superoxide production by monocytes. This suppression was not due to cell death. Chemical analysis identified the water-soluble components to be terpinen-4-ol, alpha-terpineol and 1,8-cineole. When examined individually, terpinen-4-ol significantly suppressed fMLP- and LPS- but not PMA-stimulated superoxide production; alpha-terpineol significantly suppressed fMLP-, LPS- and PMA-stimulated superoxide production; 1,8-cineole was without effect. CONCLUSION: Tea tree oil components suppress the production of superoxide by monocytes, but not neutrophils, suggesting the potential for selective regulation of cell types by these components during inflammation.

Anti-Infective Agents, Local↗
PubMed2006

Repellency of MyggA Natural spray (para-menthane-3,8-diol) and RB86 (neem oil) against the tick Ixodes ricinus (Acari: Ixodidae) in the field in east-central Sweden.

In the field in south-central Sweden, we tested by randomised, standardised methodology the potential anti-tick repellent activity of two concentrations of MyggA Natural spray (containing PMD) (4.2 and 3.2 g/m2) and one of RB86 (with 70% neem oil containing azadirachtin) (3 g/m2) to host seeking nymphs of Ixodes ricinus. Each substance was applied separately to 1 m2 cotton flannel cloths. Nymphal ticks on the cloths, pulled over the vegetation, were recorded at 10-m stops. Nymphal numbers recorded differed significantly between treated cloths [4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB86/m2] and the untreated control (df = 3, chi2 = 112.74, P < 0.0001). Nymphal numbers also differed significantly among collectors (df = 3, chi2 = 15.80, P < 0.001). Repellency of treated cloths, i.e., 4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB 86/m2 declined from day 0 (i.e. the day of impregnation) to day 3 after impregnation from 77 to 24%, 58 to 16% and 47 to 0.5%, respectively. This study suggests that all three treatments have significant repellent activities against I. ricinus nymphs.

Animals↗
PubMed2005

Effects of mechanical wounding on essential oil composition and emission of volatiles from Minthostachys mollis.

Plant tissues may show chemical changes following damage. This possibility was analyzed for Minthostachys mollis, a Lamiaceae native to Central Argentina with medicinal and aromatic uses in the region. Effects of mechanical damage on its two dominant monoterpenes, pulegone and menthone, were analyzed by perforating M. mollis leaves and then assessing essential oil composition at 24, 48, and 120 hr; emission of volatiles was also measured 24 and 48 hr after wounding. Mechanical damage resulted in an increase of pulegone and menthone concentration in M. mollis essential oil during the first 24 hr. These changes did not occur in the adjacent undamaged leaves, suggesting a lack of systemic response. Postwounding changes in the volatiles released from M. mollis damaged leaves were also detected, most noticeably showing an increase in the emission of pulegone. Inducible chemical changes in aromatic plants might be common and widespread, affecting the specific compounds on which commercial exploitation is based.

Animals↗
PubMed2006

The mode of promoting activity of O-ethylmenthol as a transdermal absorption enhancer.

PURPOSE: The mode of action of O-ethylmenthol (MET), a promising compound to enhance transdermal drug delivery, was elucidated. Morphology of the skin treated with MET was investigated employing a laser scanning confocal microscopy. METHODS: Confocal scanning laser microscope and laser scanning microscope were employed for the morphological evaluation of the stratum corneum. To evaluate the fluidity of intercellular lipids by treatment with MET, liposomes composed of the stratum corneum lipids were prepared. RESULTS: Distribution amounts of the fluorescent probes greatly increased in the intercellular regions of the stratum corneum treated with 40% ethanol containing MET. Based on the skin surface observations, the difference in relative height between keratinocytes and intercellular regions was defined as DeltaH = DeltaH(keratinocytes) - DeltaH(intercellular space), where DeltaH is the difference in relative height, DeltaH(keratinocytes) is the height of center region in the keratinocytes, and DeltaH(intercellular space) is the height of the intercellular space. DeltaH values became negative in the skin surface treated with 40% ethanol containing MET because of the swelling in the intercellular regions. DeltaH values changed from positive to negative 15-30 min after the administration of MET. A very short period of application of MET was sufficient to induce its promoting activity. CONCLUSIONS: MET was able to change the structure of the intercellular lipids, thereby enhancing both the partitioning and diffusion of drugs through the skin.

Administration, Cutaneous↗
PubMed1986

Metabolism of monoterpenes: demonstration that (+)-cis-isopulegone, not piperitenone, is the key intermediate in the conversion of (-)-isopiperitenone to (+)-pulegone in peppermint (Mentha piperita).

Piperitenone is commonly considered to be the key intermediate in the conversion of (-)-isopiperitenone to (+)-pulegone in peppermint; however, [3H]piperitenone gave rise only to the inert metabolite (+)-piperitone when incubated with peppermint leaf discs. Under identical conditions, (-)-[3H]isopiperitenone was efficiently incorporated into (+)-pulegone, (-)-menthone, and (+)-isomenthone in leaf discs, and yielded an additional metabolite identified as (+)-cis-isopulegone; piperitenone was poorly labeled. Moreover, (+)-cis-[3H]isopulegone was rapidly converted to (+)-pulegone, (-)-menthone, and (+)-isomenthone in leaf discs, and the reduction of (+)-[3H]pulegone to (-)-menthone and (+)-isomenthone was similarly documented. Each step of the pathway was demonstrated in a crude soluble preparation from peppermint leaf epidermis and each of the relevant enzymes was partially purified in order to compare relative rates of catalysis. The results of these studies indicate that the endocyclic double bond of (-)-isopiperitenone is reduced to yield (+)-cis-isopulegone, which is isomerized to (+)-pulegone as the immediate precursor of (-)-menthone and (+)-isomenthone, and they rule out piperitenone as an intermediate of the pathway.

Biotransformation↗
PubMed1987

Ion transport across the frog olfactory mucosa: the basal and odorant-stimulated states.

The Ussing method was adapted to study the basal electrolyte transfer as well as the events that occur upon odorant stimulation in frog olfactory mucosa. The unstimulated short-circuit current was due mainly to a furosemide-sensitive ion transport system on the apical side of the olfactory mucosa. This current was not amiloride sensitive. The current-voltage relationship of the unstimulated state was linear. That of the odorant-evoked current was non-linear and amiloride-sensitive. Ouabain caused collapse of both the unstimulated and odorant-stimulated short-circuit current. In this case, voltage-clamping the tissue to non-zero values restored the odorant-evoked current with polarity depending on that of the clamping voltage. This suggested that the direction of the current is determined by that of the sodium electrochemical potential difference. Our results indicate that the unstimulated short-circuit current occurs through an apical sodium cotransport system, while the odorant-evoked current is due to odorant-activated, passive sodium channels that are amiloride sensitive.

Amiloride↗
PubMed1996

Membrane fluidity response to odorants as seen by 2H-NMR and infrared spectroscopy.

Fourier transform infrared spectroscopy (FTIR) and deuterium nuclear magnetic resonance spectroscopy (2H-NMR) have been used to study the location of two odorants, beta-ionone and menthone, in a model membrane of dimyristoylphosphatidylcholine, as well as the effect of the odorants on the structure and dynamics of the phospholipids. The interaction has been investigated for two lipid-to-odorant molar ratios, 10:1 and 1:1. The two odorants were found to affect the fluidity of the membrane. More specifically, the 2H-NMR results indicate that at a lipid-to-odorant molar ratio of 10:1, both beta-ionone and menthone increase the order of the deuterons in the interfacial and headgroup regions of the lipid while the incorporation of the odorants at a lipid-to-odorant molar ratio of 1:1 decreases the order of both the lipid headgroup and acyl chains. On the other hand, the infrared results show that the incorporation of beta-ionone and menthone decreases the phase transition temperature and cooperativity of the lipid acyl chains. The results suggest that the site of incorporation of beta-ionone and menthone is very similar in DMPC membranes.

Dimyristoylphosphatidylcholine↗