BACKGROUND

Previous mapping algorithms estimating EQ-5D index scores from the SF-12 were based on preferences from a UK community sample. However, preferences based on the general US population are most appropriate for costeffectiveness analyses done from the societal perspective in the United States.

OBJECTIVE

To provide a mapping algorithm for estimating EQ-5D index scores from the SF-12 based on a nationally representative sample and using preferences based on the general US population:

METHODS

The Medical Expenditure Panel Survey (MEPS) 2002 and 2000 data were used as independent derivation and validation sets to estimate the relationship between SF-12 scores and EQ-5D index scores, controlling for sociodemographic characteristics and comorbidity burden. Prediction equations for end-users who only have access to SF-12 scores were derived and compared. The empirical performance of censored least absolute deviations (CLAD), Tobit, and ordinary least squares (OLS) analytic methods were compared by calculating the mean prediction error in the validation set.

RESULTS

The fully specified CLAD model resulted in the lowest mean prediction error, followed by OLS and Tobit. The CLAD prediction equation based only on SF-12 scores performed better than the fully specified OLS and Tobit models.

CONCLUSIONS

The current research provides an algorithm for mapping EQ-5D index scores from the SF-12. This algorithm may provide analysts with an avenue to obtain appropriate preference-based health-related quality-of-life scores for use in cost-effectiveness analyses when only SF-12 data are available.

In C6 glioma cells stably expressing a homogeneous population of the cloned rat mu opioid receptor, the binding affinities of opioid agonists and subsequent activation of G protein were examined. Opioid receptor number in membranes of these cells was high (10-30 pmol/mg protein [3H]diprenorphine binding sites). Opioids were found to bind to the receptor with high affinity [Tyr-D-Ala-Gly-(Me)Phe-Gly-ol (DAMGO) 0.23 nM; sufentanil 0.034 nM; morphine 0.16 nM]. Activation of G protein by opioid agonists was examined by measuring the stimulation of guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) binding. Sufentanil increased [35S]GTP gamma S binding by 326% with an EC50 value of 2.39 nM. Agonist stimulation of [35S]GTP gamma S binding was stereoselective, naltrexone-reversible, and pertussis toxin-sensitive. The "intrinsic activity" of opioids at the mu receptor was reflected by the magnitude of agonist-mediated activation of G protein. The rank order of the stimulation of [35S]GTP gamma S binding was etonitazene = sufentanil = DAMGO = PLO17 = fentanyl>> morphine>> profadol>> meperidine>> butorphanol = nalbuphine = pentazocine>> cyclazocine = nalorphine>> levallorphan>> naltrexone. High affinity binding of ligands to the mu opioid receptor was reduced by the addition of sodium and guanosine diphosphate at concentrations used in the [35S]GTP gamma S binding assay. Ligand affinity was reduced in a manner correlating with "intrinsic activity". DAMGO, 1229-fold, nalbuphine 35-fold, naltrexone, 3-fold. The results presented show that the stable expression of the rat mu opioid receptor in C6 cells provides an effective tool to examine opioid receptor signal transduction mechanisms and evaluate the activity of novel opioids at the mu receptor.

Agonists at μ-opioid receptors (MORs) represent the gold standard for the treatment of severe pain. A key element of opioid analgesia is the depression of nociceptive information at the first synaptic relay in spinal pain pathways. The underlying mechanisms are, however, largely unknown. In spinal cord slices with dorsal roots attached prepared from young rats, we determined the inhibitory effect of the selective MOR agonist [d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin (DAMGO) on monosynaptic Aδ- and C-fiber-evoked EPSCs in lamina I neurons. DAMGO depressed presynaptically Aδ- and C-fiber-mediated responses, indicating that MORs are expressed on central terminals of both fiber types. We next addressed the mechanisms of presynaptic inhibition. The effect of DAMGO at both Aδ- and C-fiber terminals was mainly mediated by an inhibition of N-type voltage-dependent Ca(2+) channels (VDCCs), and to a lesser extent of P/Q-type VDCCs. Inhibition by DAMGO was not reduced by K(+) channel blockers. The rate of miniature EPSCs was reduced by DAMGO in a dose-dependent manner. The opioid also reduced Ca(2+)-dependent, ionomycin-induced EPSCs downstream of VDCCs. DAMGO had no effect on the kinetics of vesicle exocytosis in C-fiber terminals, but decreased the rate of unloading of Aδ-fiber boutons moderately, as revealed by two-photon imaging of styryl dye destaining. Together, these results suggest that binding of opioids to MORs reduces nociceptive signal transmission at central Aδ- and C-fiber synapses mainly by inhibition of presynaptic N-type VDCCs. P/Q-type VDCCs and the transmitter release machinery are targets of opioid action as well.

Oligodendrocyte (OL) loss and axon demyelination occur after spinal cord injury (SCI). OLs may be replaced, however, by proliferating NG2+ progenitor cells. Indeed, new OLs have been noted in ventral white matter after SCI. Since tissue adjacent to lesion cavities is exposed to different mediators compared with outlying spared tissue, the authors used a rat SCI model to compare NG2 cell proliferation and OL genesis adjacent to lesion cavities with that in spared tissue closer to meninges. NG2 cells proliferated throughout the first week postinjury and accumulated along lesion borders, especially within gray matter. By 3 days postinjury (dpi), new OLs were detected throughout the cross-sections; between 4 and 7 dpi, however, oligogenesis was restricted to lesion borders. New OLs derived from cells proliferating during 1-7 dpi increased dramatically by 14 dpi; most were located along lesion borders and in spared gray matter. Oligogenesis continued along lesion borders during the second week postinjury. Overall OL numbers were reduced at 3 dpi in spared tissue, but rebounded to normal levels by 14 dpi. Surprisingly, lesion borders maintained normal OL numbers at 3 dpi, which then rose to exceed preinjury levels at 7 and 14 dpi. These results indicate that oligogenesis is protracted after SCI and leads to increased OL numbers. Most new OLs are formed in regions of greatest NG2 cell proliferation. Thus, the adult spinal cord spontaneously develops a dynamic gliogenic zone along lesion borders.

Statistical properties of the ordinary least-squares (OLS), generalized least-squares (GLS), and minimum-evolution (ME) methods of phylogenetic inference were studied by considering the case of four DNA sequences. Analytical study has shown that all three methods are statistically consistent in the sense that as the number of nucleotides examined (m) increases they tend to choose the true tree as long as the evolutionary distances used are unbiased. When evolutionary distances (dij's) are large and sequences under study are not very long, however, the OLS criterion is often biased and may choose an incorrect tree more often than expected under random choice. It is also shown that the variance-covariance matrix of dij's becomes singular as dij's approach zero and thus the GLS may not be applicable when dij's are small. The ME method suffers from neither of these problems, and the ME criterion is statistically unbiased. Computer simulation has shown that the ME method is more efficient in obtaining the true tree than the OLS and GLS methods and that the OLS is more efficient than the GLS when dij's are small, but otherwise the GLS is more efficient.

Approximately 10% of newborns are born prematurely. Of these children, more than 10% will sustain neurological injuries leading to significant learning disabilities, cerebral palsy, or mental retardation, with very low birth weight infants having an even higher incidence of brain injury. Whereas intraventricular hemorrhage was the most common form of serious neurological injury a decade ago, periventricular white matter injury (PWMI) is now the most common cause of brain injury in preterm infants. The spectrum of chronic PWMI includes focal cystic necrotic lesions (periventricular leukomalacia; PVL) and diffuse myelination disturbances. Recent neuroimaging studies support that the incidence of PVL is declining, whereas diffuse cerebral white matter injury is emerging as the predominant lesion. Factors that predispose to PVL include prematurity, hypoxia, ischemia, and inflammation. It is believed that injury to oligodendrocyte (OL) progenitors contributes to the pathogenesis of myelination disturbances in PWMI by disrupting the maturation of myelin-myelin-forming oligodendrocytes. Other potential mechanisms of injury include activation of microglia and axonal damage. Chemical mediators that may contribute to white matter injury include reactive oxygen (ROS) and nitrogen species (RNS), glutamate, cytokines, and adenosine. As our understanding of the pathogenesis of PWMI improves, it is anticipated that new strategies for directly preventing brain injury in premature infants will evolve.

Self-reported health status is often measured using psychometric or utility indices that provide a score intended to summarize an individual's health. Measurements of health status can be subject to a ceiling effect. Frequently, researchers want to examine relationships between determinants of health and measures of health status. Regression methods that ignore the presence of a ceiling effect, or of censoring in the health status measurements can produce biased coefficient estimates. The Tobit regression model is a frequently used tool for modeling censored variables in econometrics research. The authors carried out a Monte-Carlo simulation study to contrast the performance of the Tobit model for censored data with that of ordinary least squares (OLS) regression. It was demonstrated that in the presence of a ceiling effect, if the conditional distribution of the measure of health status had uniform variance, then the coefficient estimates from the Tobit model have superior performance compared with estimates from OLS regression. However, if the conditional distribution had non-uniform variance, then the Tobit model performed at least as poorly as the OLS model.

Frontal cortical regions are activated by food-associated stimuli, and this activation appears to be dysregulated in individuals with eating disorders. Nevertheless, frontal control of basic unconditioned feeding responses remains poorly understood. Here we show that hyperphagia can be driven by μ-opioid receptor stimulation in restricted regions of ventral medial prefrontal cortex (vmPFC) and orbitofrontal cortex. In both ad libitum-fed and food-restricted male Sprague Dawley rats, bilateral infusions of the μ-opioid agonist [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) markedly increased intake of standard rat chow. When given a choice between palatable fat-enriched versus carbohydrate-enriched test diets, intra-vmPFC DAMGO infusions selectively increased carbohydrate intake, even in rats with a baseline fat preference. Rats also exhibited motor hyperactivity characterized by rapid switching between brief bouts of investigatory and ingestive behaviors. Intra-vmPFC DAMGO affected neither water intake nor nonspecific oral behavior. Similar DAMGO infusions into neighboring areas of lateral orbital or anterior motor cortex had minimal effects on feeding. Neither stimulation of vmPFC-localized δ-opioid, κ-opioid, dopaminergic, serotonergic, or noradrenergic receptors, nor antagonism of D1, 5HT1A, or α- or β-adrenoceptors, reproduced the profile of DAMGO effects. Muscimol-mediated inactivation of the vmPFC, and intra-vmPFC stimulation of κ-opioid receptors or blockade of 5-HT2A (5-hydroxytryptamine receptor 2A) receptors, suppressed motor activity and increased feeding bout duration-a profile opposite to that seen with DAMGO. Hence, μ-opioid-induced hyperphagia and carbohydrate intake can be elicited with remarkable pharmacological and behavioral specificity from discrete subterritories of the frontal cortex. These findings may have implications for understanding affect-driven feeding and loss of restraint in eating disorders.

Dysfunction of GABA(A) receptor-mediated inhibition is implicated in a number of neurological and psychiatric conditions including epilepsy and affective disorders. Some of these conditions have been associated with abnormal levels of certain endogenously occurring neurosteroids, which potently and selectively enhance the function of the brain's major inhibitory receptor, the GABA(A) receptor. Consistent with their ability to enhance neuronal inhibition, such steroids exhibit in animals and humans anxiolytic, anticonvulsant and anesthetic actions. Neurosteroids, exemplified by the potent progesterone metabolite, 5alpha-pregnan-3alpha-ol-20-one can be synthesized de novo in the CNS both in neurones and glia in levels sufficient to modulate GABA(A) receptor function. Neurosteroid levels are not static, but are subject to dynamic fluctuations, for example during stress, or the later stages of pregnancy. These observations suggest that these endogenous modulators may refine the function of the brain's major inhibitory receptor and thus, play an important physiological and pathophysiological role. However, given the ubiquitous expression of GABA(A) receptors throughout the mammalian CNS, changes in neurosteroid levels should be widely experienced, causing a generalized enhancement of neuronal inhibition. Such a non-specific action would seem incompatible with a physiological role. However, neurosteroid action is both brain region and neurone selective. This specificity results from a variety of molecular mechanisms including receptor subunit composition, local steroid metabolism and phosphorylation. This paper will evaluate the relative contribution these mechanisms play in defining the interaction of neurosteroids with synaptic and extra-synaptic GABA(A) receptors.

Activation of neurons in the rostral ventral medulla, by electrical stimulation or microinjection of glutamate, produces antinociception. Microinjection of opioid compounds in this region also has an antinociceptive effect, indicating that opioids activate a medullary output neuron that exerts a net inhibitory effect on nociception. When given systemically in doses sufficient to produce antinociception, morphine produces distinct, opposing responses in two physiologically identifiable classes of rostral medullary neurons. "Off-cells" are activated, and have been proposed to inhibit nociceptive transmission. "On-cells" are invariably depressed, and may have a pro-nociceptive role. Although on-cell firing is also depressed by iontophoretically applied morphine, off-cells do not respond to morphine applied in this manner. The present study used local infusion of the mu-selective opioid peptide Tyr-D-Ala-Gly-MePhe-Gly-ol-enkephalin (DAMGO) within the rostral medulla to determine whether off-cells are activated by an opioid action within this region that is sufficient to produce a behaviorally measurable antinociception. Activity of on- and off-cells was recorded before and after local infusion of DAMGO noxious heat-evoked tail flick reflex was inhibited in 17 of 28 cases. On-cell firing was profoundly depressed, and this occurred irrespective of the antinociceptive effectiveness of the injection. Off-cells were activated following DAMGO microinjections, but only in experiments in which the tail flick reflex was inhibited. Both reflex inhibition and neuronal effects were reversed following systemic administration of naloxone. These observations thus confirm the role of the on-cell as the focus of direct opioid action within the rostral medulla, and strongly support the proposal that disinhibition of off-cells is central to the antinociception actions of opioids within this region.

OBJECTIVE

We estimate the effect size of hypoglycemia risk reduction on closed-loop control (CLC) versus open-loop (OL) sensor-augmented insulin pump therapy in supervised outpatient setting.

METHODS

Twenty patients with type 1 diabetes initiated the study at the Universities of Virginia, Padova, and Montpellier and Sansum Diabetes Research Institute; 18 completed the entire protocol. Each patient participated in two 40-h outpatient sessions, CLC versus OL, in randomized order. Sensor (Dexcom G4) and insulin pump (Tandem t:slim) were connected to Diabetes Assistant (DiAs)-a smartphone artificial pancreas platform. The patient operated the system through the DiAs user interface during both CLC and OL; study personnel supervised on site and monitored DiAs remotely. There were no dietary restrictions; 45-min walks in town and restaurant dinners were included in both CLC and OL; alcohol was permitted.

RESULTS

The primary outcome-reduction in risk for hypoglycemia as measured by the low blood glucose (BG) index (LGBI)-resulted in an effect size of 0.64, P = 0.003, with a twofold reduction of hypoglycemia requiring carbohydrate treatment: 1.2 vs. 2.4 episodes/session on CLC versus OL (P = 0.02). This was accompanied by a slight decrease in percentage of time in the target range of 3.9-10 mmol/L (66.1 vs. 70.7%) and increase in mean BG (8.9 vs. 8.4 mmol/L; P = 0.04) on CLC versus OL.

CONCLUSIONS

CLC running on a smartphone (DiAs) in outpatient conditions reduced hypoglycemia and hypoglycemia treatments when compared with sensor-augmented pump therapy. This was accompanied by marginal increase in average glycemia resulting from a possible overemphasis on hypoglycemia safety.

The analysis of oligodendrocyte (OL) lineage development has been facilitated by the immunocytochemical characterization of OL-specific antigens and definition of the phenotypes sequentially acquired by differentiating OLs. The purpose of the present study was to address an enduring discrepancy between several reported cases of S100B immunodetection in CNS myelin and myelinating OLs on the one hand, and the systematic use of the S100B protein as an alleged astrocytic marker in studies of the mammalian CNS on the other. To resolve this discrepancy, we have compared the developmental distribution of EGFP+ cells in the CNS of s100b-enhanced green fluorescent protein (EGFP) (Vives et al., 2003) and cnp-EGFP (Yuan et al., 2002) mice, and examined the degree of overlap between EGFP expression and that of stage-specific markers of OL differentiation during the embryonic and postnatal phases of development. We demonstrate that the S100B protein is expressed in postnatal and adult populations of NG2+ progenitors of mouse brain, as well as in immature and mature myelinating OLs present in the brain and spinal cord of embryonic and adult mice, respectively. Comparison between EGFP and endogenous S100B expression in the s100b-EGFP and cnp-EGFP mice indicates that S100B protein expression is upregulated in immature and mature OLs. These results argue against the current view that S100B expression is restricted to the astrocytic lineage in the CNS, and indicate that the use of S100B in combination with other molecular markers will help discriminate oligodendrocytes from astrocytes.

The cytokinin receptor AHK3 of Arabidopsis thaliana plays a predominant role in shoot development. A study of the hormone-binding characteristics of AHK3 compared with the mainly root-confined receptor CRE1/AHK4 has been accomplished using a live-cell binding assay on transgenic bacteria expressing individual receptor proteins. Both receptors bound trans-zeatin (tZ) with high affinity. Scatchard analysis showed a linear function corresponding to an apparent K(D) of 1-2 nM for the AHK3 receptor-hormone complex, which is close to the K(D) (2-4 nM) for the CRE1/AHK4 receptor-hormone complex. The specific binding of tZ to both receptors was pH dependent, AHK3 being more sensitive to pH changes than CRE1/AHK4. Hormone binding was reversible, at least for the bulk of (3)H-zeatin, and influenced by monovalent cations, while divalent cations (Ca(2+), Mg(2+), Mn(2+)) at physiological concentrations had no significant effect. AHK3 differed significantly from CRE1/AHK4 in relative affinity to some cytokinins. AHK3 had an approximately 10-fold lower affinity to isopentenyladenine (iP) and its riboside, but a higher affinity to dihydrozeatin than CRE1/AHK4. For AHK3, cytokinin ribosides (tZR, iPR) and cis-zeatin had true binding activity, although lower than that of tZ. The phenylurea-derived cytokinin thidiazuron was a strong competitor and bound to the same site as did adenine-derived cytokinins. The inhibitor of cytokinin action butan-1-ol had little effect on cytokinin-receptor complex formation. The revealed properties of AHK3 suggest its specific function in root-to-shoot communication.

A growing body of evidence suggests that childhood leukemia may be initiated in utero when lymphoid and myeloid cells are not fully differentiated and are particularly susceptible to malignant transformation. A fixed effects meta-analysis examining the association between birth weight and childhood leukemia was conducted including 32 studies and 16,501 cases of all types of leukemia (OL), 10,974 cases of acute lymphoblastic leukemia (ALL), and 1,832 cases of acute myeloid leukemia (AML). The odd ratios (OR) for the association of high birth weight with OL, ALL and AML were 1.35 (95% CI: 1.24, 1.48), 1.23 (95% CI: 1.15, 1.32), and 1.40 (95% CI: 1.11, 1.76), respectively, compared with normal birth weight. Low birth weight was not associated with overall and ALL leukemia, but with AML (OR = 1.50; 95% CI: 1.05, 2.13). Per 1000 g increase in birth weight, the OR for OL was 1.18 (95% CI: 1.13, 1.23) and ALL 1.18 (95% CI: 1.12, 1.23). The combined available evidence from observational studies suggests that high birth weight is associated with an increased risk of overall leukemia and ALL. For AML the risk may be elevated at both high and low extremes of birth weight, suggesting a U-shaped association.

Proanthocyanidins, also known as condensed tannins, are oligomers or polymers of flavan-3-ol units. In spite of important breakthroughs in our understanding of the biosynthesis of the major building blocks of proanthocyanidins, (+)-catechin and (-)-epicatechin, important questions still remain to be answered as to the exact nature of the molecular species that undergo polymerization, and the mechanisms of assembly. We review the structures of proanthocyanidins reported over the past 12 years in the context of biosynthesis, and summarize the outstanding questions concerning synthesis of proanthocyanidins from the chemical, biochemical and molecular genetic perspectives.

OBJECTIVE

To investigate the in vitro antifungal activity of the components of Melaleuca alternifolia (tea tree) oil.

RESULTS

Activity was investigated by broth microdilution and macrodilution, and time kill methods. Components showing the most activity, with minimum inhibitory concentrations and minimum fungicidal concentrations of < or =0.25%, were terpinen-4-ol, alpha-terpineol, linalool, alpha-pinene and beta-pinene, followed by 1,8-cineole. The remaining components showed slightly less activity and had values ranging from 0.5 to 2%, with the exception of beta-myrcene which showed no detectable activity. Susceptibility data generated for several of the least water-soluble components were two or more dilutions lower by macrodilution, compared with microdilution.

CONCLUSIONS

All tea tree oil components, except beta-myrcene, had antifungal activity. The lack of activity reported for some components by microdilution may be due to these components becoming absorbed into the polystyrene of the microtitre tray. This indicates that plastics are unsuitable as assay vessels for tests with these or similar components.

CONCLUSIONS

This study has identified that most components of tea tree oil have activity against a range of fungi. However, the measurement of antifungal activity may be significantly influenced by the test method.

In many insect species, odorant-binding proteins (OBPs) are thought to be responsible for the transport of pheromones and other semiochemicals across the sensillum lymph to the olfactory receptors (ORs) within the antennal sensilla. In the silkworm Bombyx mori, the OBPs are subdivided into three main subfamilies; pheromone-binding proteins (PBPs), general odorant-binding proteins (GOBPs) and antennal-binding proteins (ABPs). We used the MotifSearch algorithm to search for genes encoding putative OBPs in B. mori and found 13, many fewer than are found in the genomes of fruit flies and mosquitoes. The 13 genes include seven new ABP-like OBPs as well as the previously identified PBPs (three), GOBPs (two) and ABPx. Quantitative examination of transcript levels showed that BmorPBP1, BmorGOBP1, BmorGOBP2 and BmorABPx are expressed at very high levels in the antennae and so could be involved in olfaction. A new two-phase binding assay, along with other established assays, showed that BmorPBP1, BmorPBP2, BmorGOBP2 and BmorABPx all bind to the B. mori sex pheromone component (10E,12Z)-hexadecadien-1-ol (bombykol). BmorPBP1, BmorPBP2 and BmorABPx also bind the pheromone component (10E,12Z)-hexadecadienal (bombykal) equally well, whereas BmorGOBP2 can discriminate between bombykol and bombykal. X-ray structures show that when bombykol is bound to BmorGOBP2 it adopts a different conformation from that found when it binds to BmorPBP1. Binding to BmorGOBP2 involves hydrogen bonding to Arg110 rather than to Ser56 as found for BmorPBP1.

Proanthocyanidins (PAs) and their monomeric building blocks, the (epi)-flavan-3-ols, are plant antioxidants that confer multiple human health benefits. The presence of PAs in forage crops is an important agronomic trait, preventing pasture bloat in ruminant animals. However, many consumed plant materials lack PAs, and there has been little success to date in introducing monomeric or polymeric flavan-3-ols de novo into plant tissues for disease prevention by dietary means or development of 'bloat-safe' forages. We report the introduction of PAs into plants by combined expression of a MYB family transcription factor and anthocyanidin reductase for conversion of anthocyanidin into (epi)-flavan-3-ol. Tobacco leaves expressing both transgenes accumulated epicatechin and gallocatechin monomers, and a series of dimers and oligomers consisting primarily of epicatechin units. The levels of PAs reached values that would confer bloat reduction in forage species. Expression of anthocyanidin reductase in anthocyanin-containing leaves of the forage legume Medicago truncatula resulted in production of a specific subset of PA oligomers.

Multiple sclerosis (MS) is considered to be an autoimmune disease that is directed either at myelin or at its cell of origin, the oligodendrocytes (OL). The inflammatory lesions in the central nervous system contain multiple myelin Ag-restricted and nonrestricted cell populations with the potential to mediate tissue injury. Previous studies indicate that it is possible to generate MHC class I-restricted myelin peptide-specific cytotoxic CD8 T cells, and that human adult OLs express MHC class I molecules in vitro. The purpose of this study was to demonstrate that myelin basic protein peptide-specific CD8 T cells could induce OL injury. We generated CD8 T cell lines from six healthy donors and five MS patients, and all cell lines were HLA-A2 positive. The obtained CD8 cell lines induced lysis of HLA-A2- but not HLA-A3-transfected HMy2.C1R cells in the presence of myelin basic protein peptide 110-118. In the absence of exogenous peptide, the CD8 T cell lines were cytotoxic to HLA-A2 but not to non-HLA-A2 OLs. Cytotoxicity was blocked with anti-MHC class I-blocking Ab. These results support the postulate that autoreactive CD8 cytotoxic T cells can contribute to the tissue injury in MS.

OBJECTIVE

To evaluate potential antiinflammatory properties of tea tree oil, the essential oil steam distilled from the Australian native plant, Melaleuca alternifolia.

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.

CONCLUSIONS

The water-soluble components of tea tree oil can suppress pro-inflammatory mediator production by activated human monocytes.

The precision of pharmacokinetic parameter estimates from several least squares parameter estimation methods are compared. The methods can be thought of as differing with respect to the way they weight data. Three standard methods, Ordinary Least Squares (OLS-equal weighting), Weighted Least Squares with reciprocal squared observation weighting [WLS(y-2)], and log transform OLS (OLS(ln))--the log of the pharmacokinetic model is fit to the log of the observations--are compared along with two newer methods, Iteratively Reweighted Least Squares with reciprocal squared prediction weighting (IRLS,(f-2)), and Extended Least Squares with power function "weighting" (ELS(f-xi)--here xi is regarded as an unknown parameter). The values of the weights are more influenced by the data with the ELS(f-xi) method than they are with the other methods. The methods are compared using simulated data from several pharmacokinetic models (monoexponential, Bateman, Michaelis-Menten) and several models for the observation error magnitude. For all methods, the true structural model form is assumed known. Each of the standard methods performs best when the actual observation error magnitude conforms to the assumption of the method, but OLS is generally least perturbed by wrong error models. In contrast, WLS(y-2) is the worst of all methods for all error models violating its assumption (and even for the one that does not, it is out performed by OLS(ln)). Regarding the newer methods, IRLS(f-2) improves on OLS(ln), but is still often inferior to OLS. ELS(f-xi), however, is nearly as good as OLS (OLS is only 1-2% better) when the OLS assumption obtains, and in all other cases ELS(f-xi) does better than OLS. Thus, ELS(f-xi) provides a flexible and robust method for estimating pharmacokinetic parameters.

Many studies of pain and nociception use short-lasting acute stimuli which may have limited relevance to prolonged or chronic pain states. Using extracellular single-unit recording in the dorsal horn of the rat lumbar spinal cord the present study examines the response of neurones to a long-lasting nociceptive stimulus, i.e., 50 microliter 5% formalin injected into the corresponding receptive field in the ipsilateral hind paw, and modulation of this response by an opioid. Formalin produced a distinct biphasic excitatory response in all convergent neurones tested; an immediate acute or phasic peak of neuronal firing (mean maximum 22 spikes/sec) 0-10 min post injection, and a second more prolonged tonic excitatory response (mean maximum 12 spikes/sec) over a period 20-65 min after formalin. Cells only activated by innocuous stimuli were not excited by formalin indicating the involvement of C fibre afferents in the excitatory response of convergent neurones to formalin. Both the biphasic nature and the time course of the neuronal response are similar to those observed in behavioural studies. Intrathecal DAGO (Tyr-D-AlaGlyMePheGly-ol), a potent and selective mu opioid receptor agonist, applied 20 min prior to formalin completely inhibited both peaks of excitation. Co-administration of intrathecal naloxone with the agonist restored the biphasic response. By contrast, when the administration of naloxone was delayed to 2 min post formalin so that inhibition of the first peak by DAGO pretreatment occurred, there was no subsequent second peak of activity although antagonism of the opioid would have occurred. When DAGO was applied 2 min post formalin so the initial acute response occurred, the inhibitory effect of the agonist on the second peak was far less. Thus the relative ability of DAGO to modulate the biphasic excitatory response of cells to formalin depends on whether the agonist is administered prior to or after the formalin and the appearance of the second peak may depend on the presence of the first. These results are discussed in light of the role of these neurones in nociception, opioid effects and changes in neural systems following peripheral stimuli.

The present study was undertaken to evaluate the implication of delta-opioid receptor function in neurogenesis and neuroprotection. We found that the stimulation of delta-opioid receptors by the selective delta-opioid receptor agonist SNC80 [(+)-4-[(alphaR)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide] (10 nm) promoted neural differentiation from multipotent neural stem cells obtained from embryonic C3H mouse forebrains. In contrast, either a selective micro-opioid receptor agonist, [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO), or a specific kappa-opioid receptor agonist, (-)-trans-(1S,2S)-U-50488 hydrochloride (U50,488H), had no such effect. In addition to neural differentiation, the increase in cleaved caspase 3-like immunoreactivity induced by H2O2 (3 microm) was suppressed by treatment with SNC80 in cortical neuron/glia co-cultures. These effects of SNC80 were abolished by a Trk-dependent tyrosine kinase inhibitor: (8R*,9S*,11S*)-(-)-9-hydroxy-9-methoxycarbonyl-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b,11a-triazadibenzo(a,g)cycloocta(cde)trinden-1-one (K-252a). The SNC80-induced neural differentiation was also inhibited by treatment with the protein kinase C (PKC) inhibitor, phosphatidylinositol 3-kinase (PI3K) inhibitor, mitogen-activated protein kinase kinase (MEK) inhibitor or Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor. These findings raise the possibility that delta-opioid receptors play a crucial role in neurogenesis and neuroprotection, mainly through the activation of Trk-dependent tyrosine kinase, which could be linked to PI3K, PKC, CaMKII and MEK.