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PubMed2004

Effect of monoterpenes on lipid oxidation in maize.

The monoterpenes 1,8-cineole, thymol, geraniol, menthol and camphor strongly inhibited the root growth of Zea mays L. seedlings. They induced an oxidative stress as measured by the production of malondialdehyde, conjugated dienes and peroxides. This oxidative stress depended on the length of the exposure and on the monoterpene applied. The total fatty acid content was measured and fatty acid composition was analyzed. Unsaturated fatty acids increased in the treated samples. The alcoholic and non-alcoholic monoterpenes appeared to have different modes of action.

Acyclic Monoterpenes↗
PubMed2005

The de novo design of median molecules within a property range of interest.

In this paper an application is presented of the median molecule workflow to the de novo design of novel molecular entities with a property profile of interest. Median molecules are structures that are optimised to be similar to a set of existing molecules of interest as an approach for lead exploration and hopping. An overview of this workflow is provided together with an example of an instance using the similarity to camphor and menthol as objectives. The methodology of the experiments is defined and the workflow is applied to designing novel molecules for two physical property datasets: mean molecular polarisability and aqueous solubility. This paper concludes with a discussion of the characteristics of this method.

Camphor↗
PubMed2005

Isolation and characterization of allelopathic volatiles from mugwort (Artemisia vulgaris).

Several volatile allelochemicals were identified and characterized from fresh leaf tissue of three distinct populations of the invasive perennial weed, mugwort (Artemisia vulgaris). A unique bioassay was used to demonstrate the release of volatile allelochemicals from leaf tissues. Leaf volatiles were trapped and analyzed via gas chromatography coupled with mass spectrometry. Some of the components identified were terpenes, including camphor, eucalyptol, alpha-pinene, and beta-pinene. Those commercially available were tested individually to determine their phytotoxicity. Concentrations of detectable volatiles differed in both absolute and relative proportions among the mugwort populations. The three mugwort populations consisted of a taller, highly branched population (ITH-1); a shorter, lesser-branched population (ITH-2) (both grown from rhizome fragments from managed landscapes); and a population grown from seed with lobed leaves (VT). Considerable interspecific variation existed in leaf morphology and leaf surface chemistry. Bioassays revealed that none of the individual monoterpenes could account for the observed phytotoxicity imparted by total leaf volatiles, suggesting a synergistic effect or activity of a component not tested. Despite inability to detect a single dominant phytotoxic compound, decreases in total terpene concentration with increase in leaf age correlated with decreases in phytotoxicity. The presence of bioactive terpenoids in leaf surface chemistry of younger mugwort tissue suggests a potential role for terpenoids in mugwort establishment and proliferation in introduced habitats.

Artemisia↗
PubMed1988

Properties of odour-binding glycoproteins from rat olfactory epithelium.

The specific membrane glycoproteins with high affinity for camphor and decanal were isolated from rat olfactory epithelium. Antibodies to these glycoproteins inhibited both the electroolfactogram and the binding of odorants. The enzyme immunoassay has shown these glycoproteins to be present in the olfactory epithelium of rat, mouse, guinea-pig and hamster but not in that of frog and carp. The molecular mass of the odour-binding glycoproteins from rat olfactory epithelium solubilized by Triton X-100 was approx. 140 kDa. They consisted of two subunits (88 and 55 kDa). The 88 kDa subunit was capable of binding odorants. The data obtained suggest that the glycoproteins isolated have some properties that make them plausible candidates for olfactory receptor molecules.

Aldehydes↗
PubMed1987

High-resolution crystal structure of cytochrome P450cam.

The crystal structure of Pseudomonas putida cytochrome P450cam with its substrate, camphor, bound has been refined to R = 0.19 at a normal resolution of 1.63 A. While the 1.63 A model confirms our initial analysis based on the 2.6 A model, the higher resolution structure has revealed important new details. These include a more precise assignment of sequence to secondary structure, the identification of three cis-proline residues, and a more detailed picture of substrate-protein interactions. In addition, 204 ordered solvent molecules have been found, one of which appears to be a cation. The cation stabilizes an unfavorable polypeptide conformation involved in forming part of the active site pocket, suggesting that the cation may be the metal ion binding site associated with the well-known ability of metal ions to enhance formation of the enzyme-substrate complex. Another unusual polypeptide conformation forms the proposed oxygen-binding pocket. A localized distortion and widening of the distal helix provides a pocket for molecular oxygen. An intricate system of side-chain to backbone hydrogen bonds aids in stabilizing the required local disruption in helical geometry. Sequence homologies strongly suggest a common oxygen-binding pocket in all P450 species. Further sequence comparisons between P450 species indicate common three-dimensional structures with changes focused in a region of the molecule postulated to be associated with the control of substrate specificity.

Amino Acid Sequence↗
PubMed1992

Acquisition of enhanced natural killer cell activity under anesthesia.

An increase in natural killer (NK) cell activity can be conditioned with a one trial learning paradigm to demonstrate the interaction between the central nervous system (CNS) and the immune system. In order to demonstrate learning possibilities during 'non-conscious' state, mice were anesthetized with a ketamin/rompun mixture and underwent one trial learning with odor cue as the conditioned stimulus (CS) preceding the unconditioned stimulus (US). The results indicated that mice that were exposed to camphor odor cue under the influence of anesthesia can associate the signal with the poly I:C unconditioned stimulus and were able to recall the conditioned response upon reexposure to the CS. Secondly, the conditioned association made in a conscious state can be recalled by exposure to the same olfactory odor cue in a 'non-conscious' state. The increase in the conditioned change in NK cell activity of both situations was significantly higher than the control group. The results demonstrate that learning can take place and the learned response can be recalled under the reduced awareness caused by anesthesia. The findings we report are unusual and novel in that they demonstrate that the CNS can learn new associations under conditions where the host is apparently unaware of the signals being linked. Anesthesia combined with the long interstimulus interval indicates that certain neuronal pathways in the CNS are receptive to second signals (elicited by the US) even when the second signal is separated by one day. This means the conditioned learning of a physiological response can take place unconsciously at a separate level and under situations where the host is totally unaware of the events which the brain is processing and linking as incoming information.

Anesthesia↗
PubMed1983

The antibacterial effects of calcium hydroxide apexification pastes on Streptococcus sanguis.

Four calcium hydroxide-based apexification pastes were tested for their antibacterial effects on Streptococcus sanguis. Their zones of growth inhibition on blood agar plates were measured at 2, 4, 6, and 8 days. Only the camphorated parachlorophenol and the metacresylacetate pastes showed zones of inhibition. Both of these zones of inhibition decreased with time; however, the zones of inhibition for the parachlorophenol paste decreased at a slower rate.

Calcium Hydroxide↗
PubMed1996

Lipopolysaccharide and IL-1 alpha activate CNS pathways as measured by NK cell activity.

The effect of lipopolysaccharide (LPS) on murine unstimulated and prestimulated natural killer (NK) cells and its ability to serve as an unconditioned stimulus was investigated. LPS injection induced a statistically significant increase in NK cell activity when compared with saline-treated control groups. To demonstrate the existence of communication between the peripheral immune system and the central nervous system (CNS), we used a single-trial conditioning paradigm in which camphor served as the conditioned stimulus (CS) and LPS as the unconditioned stimulus (US). Once a CS/US association is made, exposure of animals to the CS alone results in the conditioned response (i.e., increase in NK cell activity). Using 50 micrograms of LPS as the US produced a low but significant increase in NK cell activity when compared to control groups. However, 10 micrograms of LPS did not show a significant increase in NK cell activity. We also observed that interleukin-1 alpha (IL-1 alpha) injected intracisternally can serve as a US to condition a central neuroendocrine pathway. Because the dose of IL-1 alpha employed was too small to raise NK cell activity in the spleen, the NK cells themselves were formally not subjected to conditioning. These observations suggest that LPS and IL-1 alpha conditions the brain and that NK cell activity can be used as an indicator system to detect neuroendocrine signals arising from the activated pathway(s).

Animals↗
PubMed1990

Effect of reserpine on retention of the conditioned NK cell response.

The effect of reserpine and 6-hydroxydopamine on the learned conditioned natural killer (NK) cell response was investigated in mice. Reserpine given at 2.5 mg/kg, 24 hr prior to reexposure to camphor-conditioned stimulus on days 6 and 8 blocked the recall of conditioned NK cell response to a significant extent. In other words, the NK cell activity of conditioned mice, treated with reserpine and reexposed to the conditioned stimulus, was similar to the nonconditioned (NC) group. A conditioned increase in NK cell response was still evident in mice treated with 6-OHDA.

Animals↗
PubMed1995

Conditioning of the secondary cytotoxic T-lymphocyte response to YC8 tumor.

Studies from our laboratory demonstrated that conditioned resistance to the syngeneic YC8 lymphoma was established by multiple conditioned stimulus (CS)/unconditioned stimulus (US) associations. The conditioned stimulus used was exposure to the odor of camphor for 1 h and the unconditioned stimulus was an injection of DBA/2 spleen cell alloantigen that shares minor histocompatibility determinants with the YC8 lymphoma. To demonstrate a cellular basis for immune resistance to the YC8 tumor, BALB/c mice primed with DBA/2 spleen cell alloantigen were conditioned using a single trial CS/US association paradigm. Conditioned animals showed a measurable conditioned elevation of the cytotoxic T-lymphocyte (CTL) response to the YC8 tumor. Control groups in which the CS and US were not given in the proper sequence were unable to mount a conditioned response. These studies show that a secondary CTL response can be upregulated by the central nervous system (CNS).

Animals↗
PubMed1991

Binding sites of pyridine in cytochrome P-450cam.

Careful titration of oxidized cytochrome P-450cam from Pseudomonas putida with pyridine revealed deviations of the Eadie plot from linearity in the substrate-bound as well as in the substrate-free protein. A binding model which assumes two binding sites for pyridine--the iron and the camphor binding site--is able to describe completely the nonlinear Eadie plot.

Binding Sites↗
PubMed1992

Molecular modeling of the 3-D structure of cytochrome P-450scc.

Sequence-alignment studies of the bovine mitochondrial cholesterol side-chain cleavage enzyme cytochrome P-450scc with the bacterial cytochrome P-450cam (camphor hydroxylating enzyme) have been undertaken. Our novel alignment of the sequences revealed 69 identical residues and many highly conserved regions. The results of the sequence alignment studies were used to model the 3-D structure of P-450scc based on the available crystal structure of P-450cam. The major insertions in the sequence are found mainly on four external-loop regions of the molecule, while the core structure of P-450cam is retained with subtle internal modifications. The most hydrophobic of these four external loops is proposed as a candidate for membrane attachment.

Amino Acid Sequence↗
PubMed1994

Significant contribution of arginine-112 and its positive charge of Pseudomonas putida cytochrome P-450cam in the electron transport from putidaredoxin.

Cytochrome P-450cam of Pseudomonas putida is a prototype of various eukaryotic cytochrome P-450 molecules. Arg-112 located on the surface of this protein is highly conserved among various other cytochromes P-450. In this study, we constructed mutant genes for P-450cam in which Arg-112 was replaced by Gln or Glu, expressed them in Escherichia coli and purified the mutant proteins. Their enzymic activities were analyzed in the reconstituted system to determine the function of Arg-112. Kd values for d-camphor of Arg112-Gln and Arg112-Glu were much the same as those of the wild-type enzyme, whereas Kd values for the oxidized form of putidaredoxin, which is an acidic protein and is the redox partner of P-450cam, were 240 and 530 microM, respectively. These values are 8 and 19 times larger than that of the wild-type enzyme (28 microM), thereby indicating lower affinities of the mutant enzymes for the oxidized putidaredoxin. Reaction rate constants for reduction by the reduced form of putidaredoxin, measured using the stopped flow method, were 45.5, 9.0 x 10(-3) and 9.0 x 10(-4) s-1 for the wild type, Arg112-Gln and Arg112-Glu, respectively. Thus, Arg-112 of P-450cam plays an important role in the interaction with putidaredoxin and in the high efficiency of the electron transfer; the positive charge of the residue seeming to contribute to the process. The yields in Escherichia coli, the heme contents in the purified fractions and heat stability of the mutant proteins were lower than those of the wild type enzyme, suggesting that Arg-112 of P-450cam is also important for stability of P-450cam.

Arginine↗
PubMed1989

Naltrexone blocks the expression of the conditioned elevation of natural killer cell activity in BALB/c mice.

An elevation of natural killer (NK) cell activity was conditioned by the association of a camphor odor conditioning stimulus (CS) with an injection of 20 micrograms polyinosinic:poly-cytidylic acid (poly I:C), the unconditioned stimulus (US). Poly I:C elicits the production and secretion of interferon (IFN), which induces an increase in NK cell activity. Reexposure to the CS occurred on Days 3 and 5 after the association trial on Day 0. Immediately following the CS exposure on Day 5, 1 microgram poly I:C was administered to all animals. This procedure resulted in an increased NK cell activity in the conditioned (CND), but not the nonconditioned (NC), mice. In this study we have shown that the expression of the conditioned response was blocked by an injection of naltrexone (NTX) at 10 mg/kg ip when given immediately prior to the two test CS odor exposures. Peripheral treatment (ip) with a quaternary form of naltrexone (QNTX), which is a less potent opiate antagonist, at the same dose and at the same time relative to the CS odor reexposure did not block the conditioned response. The formation of the conditioned association did not appear to be disrupted by NTX at the 10 mg/kg dose when given immediately prior to the trial odor exposure on Day 0. No modulation of NK cell activity was observed in any of the control groups treated with naltrexone or the quaternary analog. Because of the inability of the QNTX to block the conditioned response, we hypothesize that the opiate receptors involved in the conditioned response and blocked by NTX were within the central nervous system (CNS). Whether this response is peripherally or centrally mediated, we have shown that opiate receptors represent part of the mechanism which mediates the conditioned augmentation of NK cell activity.

Animals↗
PubMedDate not supplied

Characterization of Escherichia coli mutants with altered ploidy.

We describe the isolation and characterization of new mutants in the cell cycle of Escherichia coli. The mutants were selected as gain of function mutants that are able to maintain more than the normal number of chromosomes. Our increased ploidy mutants were isolated as resistant to camphor vapours, which selects for cells with more chromosomes than normal. The mutants (called mbr for moth-ball-resistant) map to four chromosomal locations: mbrA at 68 min; mbrB at 88.5 min; mbrC at 89.5 min; and mbrD at 90 min. To investigate the nature of these cell cycle mutants, we have coupled them with defects in recA, to test for induction of the SOS response, and dam, to determine if methylation is required for mbr function. Based on the results of these and other tests, we have made a preliminary placement of the mbr mutants within the context of the cell cycle. mbrA mutations appear to be defective in the coupling of the DNA replication cycle to the cell division cycle, and as such, may define a new link between the two processes. mbrB does not seem to be able to coordinate the cell cycle and the growth rate of the cell. mbrC appears to be defective in partitioning of chromosomes. mbrD, which may be allelic to rpoB (a subunit of RNA polymerase), appears to be defective in either chromosomal partitioning or the later stages of DNA replication.

Camphor↗
PubMed2004

Substrate modulates compound I formation in peroxide shunt pathway of Pseudomonas putida cytochrome P450(cam).

The active oxygenating intermediate, a ferryl-oxo-(II) porphyrin cation radical (compound I), in substrate-bound cytochrome P450(cam) (P450(cam)) has eluded detection and kinetic analysis for several decades. Upon rapid mixing of peroxides-H(2)O(2) and m-CPBA with substrate-bound forms of P450(cam), we observed an intermediate with spectral features characteristic of compound I. Unlike in H(2)O(2), kinetic investigation on the reaction of m-CPBA with various substrate (camphor, adamantone, and norcamphor)-bound P450(cam) and its Y96A mutant shows a preferential binding of the aromatic end group of m-CPBA to the active-site of the enzyme and modulation of compound I formation by the local environment of heme active-site. The results presented in this paper describe the importance of heme environment in modulating formation of compound I, and form the first kinetic analysis of this intermediate in the peroxide shunt pathway of substrate-bound P450(cam).

Camphor 5-Monooxygenase↗
PubMed2004

Functional diversity of cytochrome P450s of the white-rot fungus Phanerochaete chrysosporium.

The functional diversity of cytochrome P450s (P450s) of the white-rot basidiomycete, Phanerochaete chrysosporium, was studied. A series of compounds known to be P450 substrates of other organisms were utilized for metabolic studies of P. chrysosporium. Metabolic conversions of benzoic acid, camphor, 1,8-cineol, cinnamic acid, p-coumaric acid, coumarin, cumene, 1,12-dodecanediol, 1-dodecanol, 4-ethoxybenzoic acid, and 7-ethoxycoumarin were observed with P. chrysosporium for the first time. 1-Dodecanol was hydroxylated at seven different positions to form 1,12-, 1,11-, 1,10-, 1,9-, 1,8-, 1,7-, and 1,6-dodecandiols. The effect of piperonyl butoxide, a P450 inhibitor, on the fungal conversion of 1-dodecanol was also investigated, indicating that hydroxylation reactions of 1-dodecanol were inhibited by piperonyl butoxide in a concentration-dependent manner. With 11 substrates, 23 hydroxylation reactions and 2 deethylation reactions were determined and 6 products were new with the position of hydroxyl group incorporated. In conclusion, fungal P450s were shown to have diverse and unique functions.

Alkanes↗
PubMed2006

Effect of a topical antimicrobial paste on healing after extraction of molars in HIV positive patients: randomised controlled clinical trial.

AIM: To assess the efficacy of a medicated dressing in the socket on the healing after dental extractions in HIV positive patients. PATIENTS AND METHODS: Forty HIV positive patients with CD4 counts below 200 cells/mm(3) who were to have molar teeth extracted were randomly allocated to have the socket dressed with a medicated paste (Rifocort) with camphorated parachlorophenol and iodoform) and sutured (treated group), or merely sutured (control group). RESULTS: The sockets in the treated group healed more quickly than in the control group.

Administration, Topical↗