Isotopic Shift of Atom-Dimer Efimov Resonances in K-Rb Mixtures: Critical Effect of Multichannel Feshbach Physics

Multichannel Efimov physics is investigated in ultracold heteronuclear admixtures of K and Rb atoms. We observe a shift in the scattering length where the first atom-dimer resonance appears in the ^{41}K-^{87}Rb system relative to the position of the previously observed atom-dimer resonance in the ^{40}K-^{87}Rb system. This shift is well explained by our calculations with a three-body model including van der Waals interactions, and, more importantly, multichannel spinor physics. With only minor differences in the atomic masses of the admixtures, the shift in the atom-dimer resonance positions can be cleanly ascribed to the isolated and overlapping Feshbach resonances in the ^{40}K-^{87}Rb and ^{41}K-^{87}Rb systems, respectively. Our study demonstrates the role of multichannel Feshbach physics in determining Efimov resonances in heteronuclear three-body systems.

Narrow-linewidth light source for a coherent Raman transfer of ultracold molecules

We describe a tunable two-color CW light source sufficient for realizing a coherent Raman transfer between two molecular states that are more than 0.5 eV (120 THz) apart. The simultaneous frequency stabilization of 901 nm and 655 nm light was achieved by locking diode lasers to a single ultralow expansion cavity with dual wavelengths coating. By utilizing offset-locking and optical phase-locked loop (OPLL), we ensured a large mode-hop free tuning range (> 2 GHz). The obtained short term linewidth (<10 Hz) and the linear drift of frequency (65 mHz/s) were both sufficient to eliminate the influence of laser linewidths on the efficiency of coherent Raman transition.

Identification of a functional luciferase gene in the non-luminous diurnal firefly, Lucidina biplagiata

We isolated a luciferase gene (LbLuc) from the non-luminous diurnal firefly, Lucidina biplagiata, with high similarity to that from the nocturnal firefly, Photinus pyralis. The recombinant LbLuc showed luminescence activity comparable to that of the luciferases from P. pyralis and Luciola cruciata. To understand the non-luminosity of L. biplagiata, we determined the amount of luciferase in the adult specimen using the luciferin-luciferase reaction and found that the content of luciferase in L. biplagiata was estimated to be only 0.1% of that in L. cruciata. As previously reported, the content of luciferin in L. biplagiata was less than 0.1% of that in L. cruciata. Thus, the non-luminosity of L. biplagiata might be explained by low levels of both luciferase and luciferin.

Coherent transfer of photoassociated molecules into the rovibrational ground state

We report on the direct conversion of laser-cooled 41K and 87Rb atoms into ultracold 41K87Rb molecules in the rovibrational ground state via photoassociation followed by stimulated Raman adiabatic passage. High-resolution spectroscopy based on the coherent transfer revealed the hyperfine structure of weakly bound molecules in an unexplored region. Our results show that a rovibrationally pure sample of ultracold ground-state molecules is achieved via the all-optical association of laser-cooled atoms, opening possibilities to coherently manipulate a wide variety of molecules.

Site-specific mutagenesis of the calcium-binding photoprotein aequorin

The luminescent protein aequorin from the jellyfish Aequoria victoria emits light by an intramolecular reaction in the presence of a trace amount of Ca(2+). In order to understand the mechanism of the reaction, a study of structure-function relationships was undertaken with respect to modifying certain of its amino acid residues. This was done by carrying out oligonucleotide-directed site-specific mutagenesis of apoaequorin cDNA and expressing the mutagenized cDNA in Escherichia coli. Amino acid substitutions were made at the three Ca(2+)-binding sites, the three cysteines, and a histidine in one of the hydrophobic regions. Subsequent assay of the modified aequorin showed that the Ca(2+)-binding sites, the cysteines, and probably the histidine all play a role in the bioluminescence reaction of aequorin.

Cloning and characterization of the homologous genes of firefly luciferase in the mealworm beetle, Tenebrio molitor

Three homologous genes of firefly luciferase were cloned from the non-luminous beetle Tenebrio molitor. Three gene products for homologues, TmLL-1, TmLL-2 and TmLL-3, showed fatty acyl-coenzyme A (acyl-CoA) synthetic activity, but not luciferase activity with firefly luciferin. The transcripts were detected through the developmental stages in T. molitor. These results suggested that firefly luciferase was evolved from a fatty acyl-coenzyme A synthetase by gene duplications in the insect.

Retrons, msDNA, and the bacterial genome

Retrons are distinct DNA sequences that code for a reverse transcriptase (RT) similar to the RTs produced by retroviruses and other types of retroelements. Retron DNAs are commonly associated with prophage DNA and are found in the genomes of a wide variety of different bacteria. The retron RT is used to synthesize a strange satellite DNA known as msDNA. msDNA is actually a complex of DNA, RNA, and probably protein. It is composed of a small, single-stranded DNA, linked to a small, single-stranded RNA molecule. The 5' end of the DNA molecule is joined to an internal guanosine residue of the RNA molecule by a unique 2'-5' phosphodiester bond. msDNA is produced in many hundreds of copies per cell, but its function remains unknown. Although retrons are absent from the genome of most members of a population of related bacteria, retrons may not be entirely benign DNAs. Evidence is beginning to suggest that retron elements may produce small but potentially significant effects on the host cell. This includes the generation of repeated copies of the msDNA sequence in the genome, and increasing the frequency of spontaneous mutations. Because these events involve the retron RT, this may represent a source of reverse transcription in the bacterial cell. Thus, the process of reverse transcription, a force that has profoundly affected the content and structure of most eukaryotic genomes, may likewise be responsible for changes in some prokaryotic genomes.

Direct nondestructive imaging of magnetization in a spin-1 Bose-Einstein gas

Polarization-dependent phase-contrast imaging is used to resolve the spatial magnetization profile of an optically trapped ultracold gas. This probe is applied to Larmor precession of degenerate and nondegenerate spin-1 87Rb gases. Transverse magnetization of the Bose-Einstein condensate persists for the condensate lifetime, with a spatial response to magnetic field inhomogeneities consistent with a mean-field model of interactions. In comparison, the magnetization of the non-condensed gas decoheres rapidly. Rotational symmetry implies that the Larmor frequency of a spinor condensate be density independent, and thus suitable for precise magnetometry with high spatial resolution.

Observation of heteronuclear Feshbach resonances in a mixture of bosons and fermions

Three magnetic-field induced heteronuclear Feshbach resonances were identified in collisions between bosonic 87Rb and fermionic 40K atoms in their absolute ground states. Strong inelastic loss from an optically trapped mixture was observed at the resonance positions of 492, 512, and 543+/-2 G. The magnetic-field locations of these resonances place a tight constraint on the triplet and singlet cross-species scattering lengths, yielding (-281+/-15)a(0) and (-54+/-12)a(0), respectively. The width of the loss feature at 543 G is 3.7+/-1.5 G wide; this broad Feshbach resonance should enable experimental control of the interspecies interactions.

Sodium Bose-Einstein condensates in the F = 2 state in a large-volume optical trap

We have investigated the properties of Bose-Einstein condensates of sodium atoms in the upper hyperfine ground state. Condensates in the high-field seeking [F=2, m(F)=-2> state were created in a large volume optical trap from initially prepared [F=1, m(F)=-1> condensates using a microwave transition at 1.77 GHz. We found condensates in the stretched state [F=2, m(F)=-2> to be stable for several seconds at densities in the range of 10(14) atoms/cm(3). In addition, we studied the clock transition [F=1, m(F)=0> --> [F=2, m(F)=0> in a sodium Bose-Einstein condensate and determined a density-dependent frequency shift of (2.44+/-0.25+/-0.5) x 10(-12) Hz cm(3).

Analysis of sequential immunoglobulin E-binding epitope of Japanese cedar pollen allergen (Cry j 2) in humans, monkeys and mice

BACKGROUND

Japanese cedar (Cryptomeria japonica; CJ) pollinosis has been reported to occur naturally in Japanese monkeys (Macaca fuscata) as well as in humans. Most human patients and monkeys with pollinosis have specific IgE for Cry j 2, a major allergen of CJ pollen.

OBJECTIVE

The main purpose of this study was to identify IgE B cell epitopes of Cry j 2 using a synthetic peptide in humans, monkeys and mice.

METHODS

We synthesized 38 overlapping peptides that span the entire length of Cry j 2. We examined the B cell epitopes of Cry j 2 that are recognized by IgE in the sera of human patients and monkeys with pollinosis and immunized mice using synthetic peptides of Cry j 2. We also examined the reaction of Cry j 2-specific mouse monoclonal IgG antibodies to the peptides. Furthermore, we conducted a histamine release assay with leucocytes from a pollinosis patient using human serum albumin (HSA) conjugated with the peptides as a B cell epitope.

RESULTS

We found that 16 of the 20 pollinosis patients who had specific IgE to Cry j 2 also exhibited IgE reaction with some Cry j 2 peptides. Of these 16 patients, 10 exhibited IgE reaction with Cry j 2 peptide no. 13 (121GQCKWVNGREICNDRDRPTA140). Five of the seven monkeys with CJ pollinosis exhibited a reaction with peptide no. 13. Furthermore, IgE in mice immunized with Cry j 2 and two mouse monoclonal IgG antibodies reacted with peptide no. 13. Peptide no. 13-conjugated HSA showed the release of histamine from basophils. Furthermore, to determine the minimum epitope in peptide no. 13, we conducted an enzyme-linked immunosorbent assay inhibition test. The core of the epitope in humans, monkeys and mice was 124KWVNGREI131.

CONCLUSION

We found that 124KWVNGREI131 is an important B cell epitope recognized by IgE in humans, monkeys and mice.

Analysis of HLA in children with gelatin allergy

Systemic immediate reactions including anaphylaxis to gelatin in vaccines have been reported. However, the number of such reports is very small compared with the number of children exposed to gelatin. The present study was designed to investigate whether susceptibility or resistance to gelatin allergy is associated with human leukocyte antigen (HLA) class II gene. Blood samples were obtained from 49 patients with gelatin allergy and specific IgE to gelatin. DNA-based HLA class II typing was performed to determine the DRB1, DQB1 and DPB1 alleles. Genotype frequencies were compared with those found in 240 unrelated controls. The frequency of DQB1*0303 (55.1%) was significantly higher in the patients than in the control subjects (32.1%). The frequency of DPB1*0402 was also significantly higher in the patients (32.7%) than in the control subjects (15.4%). On the other hand, the frequency of subjects carrying DRB1*15 (DRB1*1501 and DRB1*1502) was significantly lower among the patients group (18.4%) than among the controls (40.8%). We found that DQB1*0303 and DPB1*0402 were positively associated with the IgE response for gelatin, while DRB1*15 was negatively associated with it.

Prolipoprotein signal peptidase of Escherichia coli requires a cysteine residue at the cleavage site

A signal peptidase specifically required for the secretion of the lipoprotein of the Escherichia coli outer membrane cleaves off the signal peptide at the bond between a glycine and a cysteine residue. This cysteine residue was altered to a glycine residue by guided site-specific mutagenesis using a synthetic oligonucleotide and a plasmid carrying an inducible lipoprotein gene. The induction of mutant lipoprotein production was lethal to the cells. A large amount of the prolipoprotein was accumulated in the outer membrane fraction. No protein of the size of the mature lipoprotein was detected. These results indicate that the prolipoprotein signal peptidase requires a glyceride modified cysteine residue at the cleavage site.

Screening of the antibacterial effects of a variety of essential oils on respiratory tract pathogens, using a modified dilution assay method

The purpose of this study was to examine the antibacterial effects of a wide variety of essential oils on major respiratory tract pathogens. The antibacterial activity of 14 essential oils and their major components was evaluated by agar-plate dilution assay under sealed conditions, with agar used as a stabilizer for homogeneous dispersion. Of the selected strains of four major bacteria causing respiratory tract infection, Haemophilus influenzae was most susceptible to the essential oils, followed by Streptococcus pneumoniae and Streptococcus pyogenes. Staphylococcus aureus was less susceptible. No cross-resistance was observed between penicillin-sensitive and penicillin-resistant S. pneumoniae. Escherichia coli, used as a control bacterium, showed the lowest susceptibility. Essential oils containing aldehyde or phenol as a major component showed the highest antibacterial activity, followed by the essential oils containing terpene alcohols. Other essential oils, containing terpene ketone, or ether, had much weaker activity, and an oil containing terpene hydrocarbon was inactive. Based on these findings, thyme (wild, red, and geraniol types), cinnamon bark, lemongrass, perilla, and peppermint oils were selected for further evaluation of their effects on respiratory tract infection.

Isolation and properties of the luciferase stored in the ovary of the scyphozoan medusa Periphylla periphylla

Bioluminescence of the medusa Periphylla is based on the oxidation of coelenterazine catalyzed by luciferase. Periphylla has two types of luciferase: the soluble form luciferase L, which causes the exumbrellar bioluminescence display of the medusa, and the insoluble aggregated form, which is stored as particulate material in the ovary, in an amount over 100 times that of luciferase L. The eggs are especially rich in the insoluble luciferase, which drastically decreases upon fertilization. The insoluble form could be solubilized by 2-mercaptoethanol, yielding a mixture of luciferase oligomers with molecular masses in multiples of approximately 20 kDa. Those having the molecular masses of 20 kDa, 40 kDa, and 80 kDa were isolated and designated, respectively, as luciferase A, luciferase B, and luciferase C. The luminescence activities of Periphylla luciferases A, B, and C were 1.2 approximately 4.1 x 10(16) photon/mg. s, significantly higher than any coelenterazine luciferase known, and the quantum yields of coelenterazine catalyzed by these luciferases (about 0.30 at 24 degrees C) are comparable to that catalyzed by Oplophorus luciferase (0.34 at 22 degrees C), which has been considered the most efficient coelenterazine luciferase until now. Luciferase L (32 kDa) could also be split by 2-mercaptoethanol into luciferase A and an accessory protein (approx. 12 kDa), as yet uncharacterized. Luciferases A, B, and C are highly resistant to inactivation: their luminescence activities are only slightly diminished at pH 1 and pH 11 and are enhanced in the presence of 1 approximately 2 M guanidine hydrochloride; but they are less stable to heating than luciferase L, which is practically unaffected by boiling.

Anaphylaxis to gelatin-containing rectal suppositories

BACKGROUND

Some children--though the number is few-have been sensitized with gelatin.

OBJECTIVE

To investigate the relationship between the presence of antigelatin IgE and anaphylaxis to gelatin-containing rectal suppository, we measured antigelatin IgE in the sera of the children with anaphylaxis.

METHODS

Ten children showed systemic allergic reactions, including anaphylaxis, to a chloral hydrate rectal suppository containing gelatin (231 mg/dose) that had been used as a sedative. These children's clinical histories and serum samples were submitted from physicians to the National Institute of Infectious Diseases during a 2-year period from 1996 to 1997.

RESULTS

Of the 10 children, 5 showed apparent anaphylaxis, including hypotension and/or cyanosis, along with urticaria or wheezing; 2 showed both urticaria and wheezing without hypotension or cyanosis; the other 3 showed only urticaria. All of the children had antigelatin IgE (mean value +/- SD, 7.9 +/- 8.4 Ua/mL). As a control, samples from 250 randomly selected children had no antigelatin IgE. These findings suggest that the 10 children's systemic allergic reactions to this suppository were caused by the gelatin component.

CONCLUSION

Gelatin-containing suppositories must be used with the same caution as gelatin-containing vaccines and other medications.

Heat-shock-induced proteins from Myxococcus xanthus

Optimal conditions for two-dimensional gel electrophoresis of total cellular proteins from Myxococcus xanthus were established. Using these conditions, we analyzed protein patterns of heat-shocked M. xanthus cells. Eighteen major spots and 15 minor spots were found to be induced by heat shock. From N-terminal sequences of 15 major spots, DnaK, GroEL, GroES, alkyl hydroperoxide reductase, aldehyde dehydrogenase, succinyl coenzyme A (CoA) synthetase, 30S ribosomal protein S6, and ATP synthase alpha subunit were identified. Three of the 18 major spots had an identical N-terminal sequence, indicating that they may be different forms of the same protein. Although a DnaK homologue, SglK, has been identified in M. xanthus (R. M. Weimer, C. Creghton, A. Stassinopoulos, P. Youderian, and P. L. Hartzell, J. Bacteriol. 180:5357-5368, 1998; Z. Yang, Y. Geng, and W. Shi, J. Bacteriol. 180:218-224, 1998), SglK was not induced by heat shock. In addition, there were seven substitutions within the N-terminal 30-residue sequence of the newly identified DnaK. This is the first report to demonstrate that succinyl CoA synthetase, 30S ribosomal protein S6, and ATP synthase alpha subunit are heat shock inducible.

Use of antiserum-coated latex particles for serotyping Streptococcus pneumoniae

The Quellung reaction provides a standard means for serotyping Streptococcus pneumoniae, but it requires microscopic examination with skillful technique. We have developed an improved agglutination method with anti-rabbit IgG-coated latex particles, which are sensitized with pooled antisera for serotyping/serogrouping S. pneumoniae. Our method is as specific and sensitive as the Quellung test, and much easier to perform.

Realization of Bose-Einstein condensates in lower dimensions

Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps in which the energy-level spacing in one or two dimensions exceeds the interaction energy between atoms, realizing condensates of lower dimensionality. The crossover into two-dimensional and one-dimensional condensates was observed by a change in aspect ratio and by the release energy converging to a nonzero value when the number of trapped atoms was reduced.

Effect of sealing and Tween 80 on the antifungal susceptibility testing of essential oils

Concentrations of essential oils showing high volatility decreased substantially in broth and agar media when incubated under open conditions. The decrease in the half life was from 0.7 to 38 hr in broth medium at 27 C. When evaporation was prevented by sealing, MIC values against Aspergillus fumigatus, Candida albicans and Trichophyton mentagrophytes by broth or agar dilution assay were lowered two to eight-fold, as compared with those obtained under open conditions. Addition of Tween 80 caused a rise of the MICs against A. fumigatus by two to four-fold in broth dilution assay, but little affected the MICs in agar dilution assay.

The msDNAs of bacteria

msDNAs are small, structurally unique satellite DNAs found in a number of Gram-negative bacteria. Composed of hundreds of copies of single-stranded DNA--hence the name multicopy single-stranded DNA--msDNA is actually a complex of DNA, RNA, and probably protein. These peculiar molecules are synthesized by a reverse transcription mechanism catalyzed by a reverse transcriptase (RT) that is evolutionarily related to the polymerase found in the HIV virus. The genes, including the RT gene, responsible for the synthesis of msDNA are encoded in a retron, a genetic element that is carried on the bacterial chromosome. The retron is, in fact, the first such retroelement to be discovered in prokaryotic cells. This report is a comprehensive review of the many interesting questions raised by this unique DNA and the fascinating answers it has revealed. We have learned a great deal about the structure of msDNA: how it is synthesized, the structure and functions of the RT protein required to make it, its effects on the host cell, the retron element that encodes it, its possible origins and evolution, and even its potential usefulness as a practical genetic tool. Despite the impressive gains in our understanding of the msDNAs, however, the simple, fundamental question of its natural function remains an enduring mystery. Thus, we have much more to learn about the msDNAs of bacteria.

Observation of vortex phase singularities in Bose-Einstein condensates

We have observed phase singularities due to vortex excitation in Bose-Einstein condensates. Vortices were created by moving a laser beam through a condensate. They were observed as dislocations in the interference fringes formed by the stirred condensate and a second unperturbed condensate. The velocity dependence for vortex excitation and the time scale for re-establishing a uniform phase across the condensate were determined.

The role of nitric oxide in the gastric acid secretion induced by ischemia-reperfusion in the pylorus-ligated rat

In a rat model of the ischemia-reperfusion with pylorus ligation, gastric ulcer was formed, although gastric acid secretion was reduced. When the polymorphonuclear leukocytes were inactivated in advance, gastric ulcer was not formed, but acid secretion was increased, indicating that gastric acid is not a cause of the ulcer formation in this model. The mechanism of gastric acid suppression accompanied by ischemia-reperfusion was examined in relation to the role of oxygen-free radicals in this rat model. Prior administration of superoxide dismutase did not modulate acid secretion, but N-nitro-L-arginine methyl ester (L-NAME) increased acid secretion. The action of L-NAME was antagonized specifically by L-arginine, but not by D-arginine. S-nitroso-N-acetylpenicillamine did not inhibit basal acid secretion but antagonized the action of L-NAME. Aminoguanidine increased significantly the gastric acid output that was suppressed by ischemia-reperfusion. When polymorphonuclear leukocytes were inactivated by treatment with their antibody, the gastric acid output recovered to the level in the pylorus-ligated rat without ischemia-reperfusion. These results suggested that nitric oxide (NO) produced by the infiltrated polymorphonuclear leukocytes plays an important role in the suppression of acid secretion induced by ischemia-reperfusion.

Preclinical evaluation of an immunotherapeutic peptide comprising 7 T-cell determinants of Cry j 1 and Cry j 2, the major Japanese cedar pollen allergens

BACKGROUND

Peptide immunotherapy is a new approach to treating allergic diseases, but a therapeutic peptide for Japanese cedar pollinosis has not yet been developed.

OBJECTIVE

The aim of this study is to prepare and preclinically evaluate a hybrid peptide comprising 7 T-cell determinants of Cry j 1 and Cry j 2, the major Japanese cedar pollen allergens.

METHODS

The recombinant hybrid peptide was prepared after immunodominance of 7 T-cell determinants was confirmed by means of PBMC proliferation assay in 113 volunteers with pollinosis. The hybrid peptide was compared with a mixture of the 7 T-cell determinants in a dose-dependent PBMC proliferation assay in 6 volunteers with pollinosis. PBMC proliferation and binding activity of serum IgE antibody against the hybrid peptide, Cry j 1, and Cry j 2 were investigated in 48 volunteers with pollinosis.

RESULTS

The hybrid peptide induced T-cell proliferation with an average 100-fold lower concentration than a mixture of the 7 peptides. PBMCs from 44 (92%) of 48 volunteers proliferated against the hybrid peptide, with significant correlation (r = 0.87) in T-cell proliferation against Cry j 1 and Cry j 2. No serum IgE antibodies specific to Cry j 1 or Cry j 2 bound to the hybrid peptide.

CONCLUSION

A hybrid peptide comprising 7 T-cell determinants has the potential for inducing T-cell proliferative responses that is superior to the potential of a mixture of the T-cell determinants and comparable with that of Cry j 1 and Cry j 2. The hybrid peptide will be of use in specific immunotherapy against Japanese cedar pollinosis.

Specific IgE and IgG to gelatin in children with systemic cutaneous reactions to Japanese encephalitis vaccines

BACKGROUND

Systemic allergic reactions to Japanese encephalitis (JE) vaccine that include urticaria, angioedema, and rash have been reported. In Japan, children who suffered from allergic immediate-type reactions to JE vaccine had antigelatin IgE in their sera. However, the immunologic mechanism of allergic nonimmediate-type reactions that consist of cutaneous signs appearing several hours or more after JE vaccination has not been defined.

METHODS

Serum samples were taken from 28 children who showed allergic nonimmediate-type cutaneous reactions to JE vaccine. Furthermore, serum samples were taken from 10 children who showed allergic immediate-type reactions with cutaneous signs and/or respiratory symptoms to JE vaccine. We have defined an immediate-type reaction as one occurring within 1 h after vaccination.

RESULTS

Of 10 children who showed immediate-type reactions, all had antigelatin IgE and IgG. Of 28 children who showed systemic nonimmediate-type reactions, one had antigelatin IgE and nine (32%) had antigelatin IgG. The child who had antigelatin IgE showed urticaria 2 h after JE vaccination.

CONCLUSION

These results suggest that some children who showed allergic nonimmediate-type reactions to JE vaccine were sensitized to gelatin.

Does matter wave amplification work for fermions?

We discuss the relationship between bosonic stimulation, density fluctuations, and matter wave gratings. It is shown that enhanced stimulated scattering, matter wave amplification, and atomic four-wave mixing do not require macroscopic occupation of a single quantum state. These processes are in principle possible for fermionic or nondegenerate samples, if they are prepared in a cooperative state. In practice, there are limitations due to short coherence times.

Antibacterial activity of essential oils and their major constituents against respiratory tract pathogens by gaseous contact

The antibacterial activity of 14 essential oils and their major constituents in the gaseous state was evaluated against Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus. For most essential oils examined, H. influenzae was most susceptible, followed by S. pneumoniae and S. pyogenes, and then S. aureus. Penicillin-susceptible and -resistant S. pneumoniae were comparable in susceptibility. Escherichia coli, which was used as a control, showed least susceptibility. A minimal inhibitory dose (MID) was introduced as a measure of the vapour activity. Among 14 essential oils, cinnamon bark, lemon-grass and thyme oils showed the lowest MID, followed by essential oils containing terpene alcohols as major constituents. The essential oils containing terpene ketone, ether and, in particular, hydrocarbon had high MIDS. The vapour activity on short exposure was comparable to that following overnight exposure, and rapid evaporation was more effective than slow evaporation of essential oils. The vapour concentration and absorption into agar of essential oils reached a maximum 1 or 2 h after rapid evaporation. These results indicate that the antibacterial action of essential oils was most effective when at high vapour concentration for a short time.

In-vitro and in-vivo anti-Trichophyton activity of essential oils by vapour contact

The minimum inhibitory doses (MIDs) of essential oils by vapour contact to inhibit the growth of Trichophyton mentagrophytes and Trichophyton rubrum on agar medium were determined using airtight boxes. Among seven essential oils examined, cinnamon bark oil showed the least MID, followed by lemongrass, thyme and perilla oils. Lavender and tea tree oils showed moderate MID, and citron oil showed the highest MID, being 320 times higher than that of cinnamon bark oil. The MID values were less than the minimum inhibitory concentration (MIC) values determined by agar dilution assay. Furthermore, the minimum agar concentration (MAC) of essential oils absorbed from vapour was determined at the time of MID determination as the second antifungal measure. The MAC value by vapour contact was 1.4 to 4.7 times less than the MAC remaining in the agar at the time of MIC determination by agar dilution assay. Using selected essential oils, the anti-Trichophyton activity by vapour contact was examined in more detail. Lemongrass, thyme and perilla oils killed the conidia, inhibited germination and hyphal elongation at 1-4 micrograms ml-1 air, whereas lavender oil was effective at 40-160 micrograms ml-1 air. The in-vivo efficacy of thyme and perilla oils by vapour contact was shown against an experimental tinea pedis in guinea pigs infected with T. mentagrophytes. These results indicated potent anti-Trichophyton action of essential oils by vapour contact.