Age differences in the behavioural economics of cannabis use: Do adolescents and adults differ on demand for cannabis and discounting of future reward?

BACKGROUND: Adolescence is a period of psychological and neural development in which harms associated with cannabis use may be heightened. We hypothesised that adolescent who use cannabis (adolescentsWUC) would have steeper delay discounting (preference for immediate over future rewards) and greater demand (relative valuation) for cannabis than adults who use cannabis (adultsWUC). METHODS: This cross-sectional study, part of the 'CannTeen' project, compared adultsWUC (n = 71, 26-29 years old) and adolescentsWUC (n = 76, 16-17 years old), and gender- and age-matched adolescent (n = 63) and adult (n = 64) controls. AdolescentsWUC and adultsWUC used cannabis 1-7 days/week and were matched on cannabis use frequency (4 days/week). The Monetary Choice Questionnaire assessed delay discounting. A modified Marijuana Purchase Task (MPT) assessed cannabis demand in adolescentsWUC and adultsWUC. The MPT yielded five indices: intensity (amount of cannabis used at zero cost), Omax (total peak expenditure), Pmax (price at peak expenditure), breakpoint (cost at which cannabis demand is suppressed to zero) and elasticity (degree to which cannabis use decreases with increasing price). Analyses were adjusted for covariates of gender, socioeconomic status, other illicit drug use. RESULTS: Both adolescentsWUC and adultsWUC had steeper delay discounting than controls (F, (1,254)= 9.13, p = 0.003, ηp2= 0.04), with no significant age effect or interaction. AdolescentsWUC showed higher intensity (F, (1,138)= 9.76, p = 0.002, ηp2= 0.07) and lower elasticity (F, (1,138)= 15.25, p < 0.001, ηp2= 0.10) than adultsWUC. There were no significant differences in Pmax, Omax or breakpoint. CONCLUSION: Individuals who use cannabis prefer immediate rewards more than controls. AdolescentsWUC, compared to adultsWUC, may be in a high-risk category with diminished sensitivity to cannabis price increases and a greater consumption of cannabis when it is free.

The CannTeen study: verbal episodic memory, spatial working memory, and response inhibition in adolescent and adult cannabis users and age-matched controls.

BACKGROUND: Preclinical and human studies suggest that adolescent cannabis use may be associated with worse cognitive outcomes than adult cannabis use. We investigated the associations between chronic cannabis use and cognitive function in adolescent and adult cannabis users and controls. We hypothesised user-status would be negatively associated with cognitive function and this relationship would be stronger in adolescents than adults. METHODS: As part of the 'CannTeen' project, this cross-sectional study assessed cognitive performance in adolescent cannabis users (n = 76; 16-17-year-olds), adolescent controls (n = 63), adult cannabis users (n = 71; 26-29-year-olds) and adult controls (n = 64). Users used cannabis 1-7 days/week. Adolescent and adult cannabis users were matched on cannabis use frequency (4 days/week) and time since last use (2.5 days). Verbal episodic memory (VEM) was assessed using the prose recall task, spatial working memory (SWM) was assessed using the spatial n-back task, and response inhibition was assessed with the stop-signal task. Primary outcome variables were: delayed recall, 3-back discriminability, and stop signal reaction time, respectively. RESULTS: Users had worse VEM than controls (F(1,268) = 7.423, p = 0.007). There were no significant differences between user-groups on SWM or response inhibition. Null differences were supported by Bayesian analyses. No significant interactions between age-group and user-group were found for VEM, SWM, or response inhibition. CONCLUSIONS: Consistent with previous research, there was an association between chronic cannabis use and poorer VEM, but chronic cannabis use was not associated with SWM or response inhibition. We did not find evidence for heightened adolescent vulnerability to cannabis-related cognitive impairment.

Assessing cross-resistance within the pyrethroids in terms of their interactions with key cytochrome P450 enzymes and resistance in vector populations.

BACKGROUND: It is important to understand whether the potential impact of pyrethroid resistance on malaria control can be mitigated by switching between different pyrethroids or whether cross-resistance within this insecticide class precludes this approach. METHODS: Here we assess the relationships among pyrethroids in terms of their binding affinity to, and depletion by, key cytochrome P450 enzymes (hereafter P450s) that are known to confer metabolic pyrethroid resistance in Anopheles gambiae (s.l.) and An. funestus, in order to identify which pyrethroids may diverge from the others in their vulnerability to resistance. We then investigate whether these same pyrethroids also diverge from the others in terms of resistance in vector populations. RESULTS: We found that the type I and II pyrethroids permethrin and deltamethrin, respectively, are closely related in terms of binding affinity to key P450s, depletion by P450s and resistance within vector populations. Bifenthrin, which lacks the common structural moiety of most pyrethroids, diverged from the other pyrethroids tested in terms of both binding affinity to key P450s and depletion by P450s, but resistance to bifenthrin has rarely been tested in vector populations and was not analysed here. Etofenprox, which also lacks the common structural moiety of most pyrethroids, diverged from the more commonly deployed pyrethroids in terms of binding affinity to key P450s and resistance in vector populations, but did not diverge from these pyrethroids in terms of depletion by the P450s. The analysis of depletion by the P450s indicated that etofenprox may be more vulnerable to metabolic resistance mechanisms in vector populations. In addition, greater resistance to etofenprox was found across Aedes aegypti populations, but greater resistance to this compound was not found in any of the malaria vector species analysed. The results for pyrethroid depletion by anopheline P450s in the laboratory were largely not repeated in the findings for resistance in malaria vector populations. CONCLUSION: Importantly, the prevalence of resistance to the pyrethroids α-cypermethrin, cyfluthrin, deltamethrin, λ-cyhalothrin and permethrin was correlated across malaria vector populations, and switching between these compounds as a tool to mitigate against pyrethroid resistance is not advised without strong evidence supporting a true difference in resistance.

Development of Aedes albopictus (Diptera: Culicidae) Larvae Under Different Laboratory Conditions.

Critical to successful application of the sterile insect technique against Aedes albopictus (Skuse) is the development of an efficient and standardized rearing protocol to be employed in the mass production system. In this study, several life history traits of Ae. albopictus were analyzed to identify upper and lower thresholds of larval density and diet concentration. Survival to pupation, time to pupation, and sex ratio were evaluated under a range of larval densities (0.5-5 larvae/ml) and food levels (0.05-1.6 mg/larva/d) using two larval diets (one locally developed; one developed by the FAO/IAEA). The larvae reared at 28 °C, at a density of 2 larvae/ml and receiving a food dose equal to 0.6 mg/larva/d of a diet consisting of 50% tuna meal, 50% bovine liver powder (the FAO/IAEA diet), and, as an additive, 0.2 g of Vitamin Mix per 100 ml of diet solution, developed in 5 d and had 90% survival to the pupal stage. With this rearing regime male pupae production 24 h after the onset of pupation was the highest; these pupae were ∼94% male.

Occurrence of natural Anopheles arabiensis swarms in an urban area of Bobo-Dioulasso City, Burkina Faso, West Africa.

The swarming behaviour of natural populations of Anopheles arabiensis was investigated by conducting transect surveys on 10 consecutive days, around dusk, from March to April and from September to October 2012 in Dioulassoba, a district of Bobo-Dioulasso city in Burkina Faso (West Africa). Swarms were observed outside, around identified larval breeding sites on the banks of the Houet River, as well as in the open-air courtyards found at the centre of many homes in the region. Swarms were found to occur in open sunlit spaces, mostly located above physical or visual cues somehow visually distinct from the surrounding area. Overall 67 and 78 swarms were observed, respectively, during the dry season (March-April) and the rainy season (September-October) of 2012, between 1.5m and 4.5m above the ground at their centre. 964 mosquitoes were collected and analysed from dry season swarms, of which most were male, and all were An. arabiensis, as were the few resting mosquitoes collected indoors. Larvae collected from breeding sites found on the banks of the Houet River mostly consisted of An. arabiensis and only a minority of Anopheles coluzzii (formerly identified as An. gambiae M form). Of 1694 mosquitoes analysed from 78 swarms in the rainy season collections, a few An. gambiae (formerly known as An. gambiae S form) males were identified, and the remainders were An. arabiensis. The majority of larvae collected during the wet season from the same breeding sites were identified as An. arabiensis followed by An. coluzzii and An. gambiae. The same pattern of species composition was observed in resting mosquitoes, though the proportion of An. arabiensis was less overwhelming. These data support the conclusion that An. arabiensis is the most prevalent species in this area, though the difference in species composition when using different population sampling techniques is noteworthy. Further studies are required for more detailed investigations of male dispersal, feeding behaviour and mating patterns in this urban setting.

Swarming behaviour in natural populations of Anopheles gambiae and An. coluzzii: review of 4 years survey in rural areas of sympatry, Burkina Faso (West Africa).

The swarming behaviour of natural populations of Anopheles gambiae and An. coluzzii (formerly known as An. gambiae S and M forms, respectively) were investigated through longitudinal surveys conducted between July 2006 and October 2009 in two rural areas of south-western Burkina Faso where these forms are sympatric. In both sites, the majority of swarms were recorded above visual markers localised among houses. In Soumousso, a wooded area of savannah, 108 pairs caught in copula from 205 swarms were sampled; in VK7, a rice growing area, 491 couples from 250 swarms were sampled. If segregated swarms were the norm in both sites, many visual markers were shared by the two forms of An. gambiae. Furthermore, mixed swarms were collected annually in frequencies varying from one site to another, though no mixed inseminations were recorded, corroborating the low hybrid rate previously reported in the field. The occurrence of inter-specific mate-recognition mechanisms, which allow individuals to avoid hybridisation, is discussed.

Efficiency of three diets for larval development in mass rearing Aedes albopictus (Diptera: Culicidae).

A fundamental step in establishing a mass production system is the development of a larval diet that promotes high adult performance at a reasonable cost. To identify a suitable larval diet for Aedes albopictus (Skuse), three diets were compared: a standard laboratory diet used at the Centro Agricoltura Ambiente, Italy (CAA) and two diets developed specifically for mosquito mass rearing at the FAO/IAEA Laboratory, Austria. The two IAEA diets, without affecting survival to the pupal stage, resulted in a shorter time to pupation and to emergence when compared with the CAA diet. At 24 h from pupation onset, 50 and 90% of the male pupae produced on the CAA and IAEA diets, respectively, had formed and could be collected. The diet received during the larval stage affected the longevity of adult males with access to water only, with best results observed when using the CAA larval diet. However, similar longevity among diet treatments was observed when males were supplied with sucrose solution. No differences were observed in the effects of larval diet on adult male size or female fecundity and fertility. Considering these results, along with the relative costs of the three diets, the IAEA 2 diet is found to be the preferred choice for mass rearing of Aedes albopictus, particularly if a sugar meal can be given to adult males before release, to ensure their teneral reserves are sufficient for survival, dispersal, and mating in the field.

Terahertz and far-infrared synchrotron spectroscopy and global modeling of methyl mercaptan, CH3(32)SH.

In this work, terahertz and Fourier transform far-infrared (FTFIR) synchrotron spectra of methyl mercaptan, CH(3)SH, have been investigated in order to provide new laboratory information for enhanced observations of this species in interstellar molecular clouds and star-forming regions. Like its methanol cousin, methyl mercaptan has particularly rich spectra associated with its large-amplitude internal rotation that extend throughout the THz and FIR regions. We have recorded new spectra for CH(3)SH from 1.1-1.5 and 1.790-1.808 THz at the University of Cologne as well as high-resolution FTFIR synchrotron spectra from 50-550 cm(-1) at 0.001 cm(-1) resolution on the far-IR beam-line at the Canadian Light Source. Assignments are reported for rotational quantum numbers up to J ≈ 40 and K ≈ 15, and torsional states up to v(t) = 2 for the THz measurements and v(t) = 3 for the FTFIR observations. The THz and FTFIR measurements together with literature results have been combined in a global analysis of a dataset comprising a total of 1725 microwave and THz frequencies together with ~18000 FTFIR transitions, ranging up to v(t) = 2 and J(max) = 30 for MW∕THz and 40 for FTFIR. The global fit employs 78 torsion-rotation parameters and has achieved a weighted standard deviation of ~1.1. A prediction list (v(t) ≤ 2, J ≤ 45 and K ≤ 20) has been generated from the model giving essentially complete coverage of observable CH(3)(32)SH transitions within the bandwidths of major new astronomical facilities such as HIFI (Heterodyne Instrument for the Far Infrared) on the Herschel Space Observatory, ALMA (Atacama Large Millimeter Array), SOFIA (Stratospheric Observatory For Infrared Astronomy) and APEX (Atacama Pathfinder Experiment) to close to spectroscopic accuracy.

Density-dependent effects in experimental larval populations of Anopheles arabiensis (Diptera: Culicidae) can be negative, neutral, or overcompensatory depending on density and diet levels.

Anopheles arabiensis Patton (Diptera: Culicidae) larvae were reared from hatching to the adult stage in the laboratory under a range of diet and larval concentrations using a factorial design. The range circumscribed most of the larval densities and diet concentrations that would allow larval growth and survival using the particular diet formulation and water volume we tested. We determined how these variables affected three outcomes, as follows: larval development rate, survival, and wing length. As has been reported previously, negative density dependence of survival as a function of increased larval density was the prevalent effect on all outcomes when diet was limiting. When diet was not limiting, density dependence was not observed, and three cases of overcompensatory survival were seen. We discuss these results in the context of diet and larval densities for mass rearing and the effect of larval competition on control strategies.

Multi-centre evaluation of pre-transfusional routine tests using 8-column format gel cards (DG Gel®).

BACKGROUND: Advances in immunohaematology laboratory practice to improve performance, cost-effectiveness and patient safety are desirable. OBJECTIVES: To perform a multi-centre evaluation of the 8-column Grifols DG Gel(®) cards and reagent system to assess its performance, suitability and adaptability to the daily blood transfusion laboratory routine in the United Kingdom. METHODS/MATERIALS: A total of 4281 immunohematological analyses {1825 ABO/D grouping, 1921 antibody screening, 75 Rh phenotyping and K antigen determination, 361 antibody identification and 99 neonates [ABO/D and DAT (direct anti-globulin test)]} were performed on 2255 specimens. All cases were run in parallel with the reference method of each laboratory (DiaMed-ID(®) cards or conventional tube technique in some cases). RESULTS: Concordant results between Grifols DG Gel(®) system and the reference method were obtained in 97·7% of tests. For ABO grouping by the Grifols DG Gel(®) system, sensitivity was 99·95%, specificity was 99·96%, predictive positive value (PPV) was 99·89% and predictive negative value (PNV) was 99·98%. For D grouping, sensitivity was 99·78%, specificity was 100%, PPV was 100% and PNV was 99·78%. For antibody screening, sensitivity was 90·63%, specificity was 99·94%, PPV was 99·32% and PNV was 99·15%. Of the Rh subgroups and K types, results were 100% concordant. For antibody specificity detection, accuracy was 96·95% for Grifols DG Gel(®) system and 95·29% for DiaMed-ID(®) system. For the newborn tests, concordant results were obtained in 100% of ABO/D grouping and in 89·9% of DAT. CONCLUSION: The Grifols DG Gel(®) 8-column system is reliable and safe for routine tests performed in the immunohaematology laboratory.

Internal rotation and spin conversion of CH3OH in solid para-hydrogen.

The quantum solid para-hydrogen (p-H2) has recently proven useful in matrix isolation spectroscopy. Spectral lines of compounds embedded in this host are unusually narrow, and several species have been reported to rotate in p-H2. We found that a p-H2 matrix inhibits rotation of isolated methanol (CH3OH) but still allows internal rotation about the C-O bond, with splittings of the E/A torsional doublet in internal rotation-coupled vibrational modes that are qualitatively consistent with those for CH3OH in the gaseous phase. This simplified high-resolution spectrum further revealed the slow conversion of nuclear spin symmetry from species E to species A in the host matrix, offering potential insight into nuclear spin conversion in astrophysical sources.

Laser diode photoacoustic detection in the infrared and near infrared spectral ranges.

A new technique for high resolution photoacoustic detection based on application of laser diodes has been developed. This method was tested and compared using identical photoacoustic instrumentation (cell and microphone) to study gas absorption in three different spectral regions, namely: the infrared range near 2100 cm(-1), CO and OCS fundamental band absorption; the ranges near 4200 and 4350 cm(-1), CH4, NH3 and N2O overtone and combination band absorption; the near infrared range near 6500 cm(-1), CO, CO2 and NH3 overtone absorption. Several types of diode laser operating at room temperature or at liquid nitrogen temperature were compared. The optimum gas pressures for the maximum sensitivity of the photoacoustic signals were found and the detection limits were estimated for all of the gases studied. The best sensitivity was achieved for NH3 at 100 ppbv. The sensitivity of the developed system was tested on detection of traces of NH3 and CO2 gases from car exhaust.

Differences in polymorphonucleocyte function and local inflammatory response between horses and ponies.

REASONS FOR PERFORMING STUDY: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response. HYPOTHESIS: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies. METHODS: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined. RESULTS: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies. CONCLUSIONS: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair. POTENTIAL RELEVANCE: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine.

Measurement of basal serum insulin concentration in the diagnosis of Cushing's disease in ponies.

A high basal plasma or serum insulin concentration is commonly accepted as an indicator of Cushing's disease in horses. The results of the combined dexamethasone suppression test and thyrotropin-releasing hormone stimulation test were compared with the basal insulin concentrations and insulin response tests of eight hyperinsulinaemic and insulin-resistant ponies with clinical histories of chronic or recurrent laminitis that were suspected of having Cushing's disease. Seven of the eight ponies had normal responses to the combined test indicating that basal insulin concentrations are not a specific indicator of the disease.

Tissue-specific segregation of TCRgamma delta+ NKT cells according to phenotype TCR repertoire and activation status: parallels with TCR alphabeta+NKT cells.

Whereas the majority of NKT cells in the mouse express an alpha beta TCR (NKTalpha beta cells), a small subset of NKT cells express a gamma delta TCR (NKTgamma delta). Here we have systematically analyzed the phenotype, TCR repertoire and activation status of NKTgamma delta cells in the thymus, liver, spleen and bone marrow of normal C57BL/6 mice. Our data indicate that NKTgamma delta cells segregate in a tissue-specific manner according to these parameters. While most NKTgamma delta cells in the thymus and liver have a recently activated CD62L(lo) phenotype and a TCR repertoire that is heavily biased to Vgamma1.1 and Vdelta6.3, the majority of NKTgamma delta cells in the spleen and bone marrow are CD62L(hi) and have a much less biased TCR repertoire. Moreover, expression of NK markers is high on NKTgamma delta cells in spleen and bone marrow but low in thymus and liver. Collectively our results reveal a tissue-specific segregation of NKTgamma delta cells that is strikingly similar to that recently described for CD1d-dependent and Cd1d-independent NKTalpha beta cells. We therefore propose that chronic TCR activation by tissue-specific endogenous ligands is a generic property of NKT cells of both the alpha beta and gamma delta lineages.

Effects of maternity on auditory event-related potentials to human sound.

Auditory event-related brain potentials (ERPs) were recorded in response to an emotional (a baby's cry) and a neutral (a word) stimulus in a group of mothers 2-5 days after childbirth (n = 20) and in control women (n = 18) who were not in the state of early motherhood. For each mother, her own infant's cry was recorded and used as the cry stimulus, whereas a strange baby's cry was used for control women. The word stimulus was identical for both groups. Stimuli were presented in intermittent trains in order to study the arousal responses to the first stimuli of the trains, and refractoriness of ERPs during stimulus repetition. The N100 responses were significantly larger in amplitude in mothers than in control women, not only to the emotional cry stimuli but also to the neutral word stimuli. The finding suggests a general increase in alertness and arousal in mothers, which may be necessary in enabling the mother to be continuously alert to her infant's needs. This allows good care of the infant and may be essential in building an emotional tie between the mother and her child.

Reversible and irreversible non-internalized LDL and methyl LDL accumulation by human fibroblasts.

In previous in vivo animal studies, we showed that low density lipoprotein (LDL) accumulated irreversibly at the edges of healing arterial lesions rather than being internalized and degraded. To see if similar LDL accumulation occurs in vitro, fibroblasts from normal and homozygous familial hypercholesterolemic (FH) subjects were incubated at 37 degrees C with 125I-LDL and 125I-methyl LDL; the latter is not recognized by any known LDL receptor. Normal fibroblast accumulation of LDL and methyl LDL (5 microg/ml) plateaued within 1 h at 200 and 100 ng/mg, respectively. With FH cells, both LDL and methyl LDL accumulation plateaued at 100 ng/mg. Lipoprotein accumulation by both cell types rose steeply at concentrations up to 15-25 microg/ml, and less so at higher concentrations. Except for degradation of LDL by normal cells, degradation was minimal, which indicated that much of the lipoprotein accumulation was unaccompanied by internalization. The accumulation of both lipoproteins by both cell types was greater at 37 degrees C than at 4 degrees C, and was inhibited between 43 and 75% by homologous unlabeled lipoprotein. To see if any accumulation was irreversible, cells were incubated with radiolabeled lipoproteins for 3 h (pulse), then with homologous unlabeled lipoproteins for up to 20 h (chase). About 50% of intact radiolabeled lipoprotein rapidly dissociated from cells into the medium in the first 4 h of the chase period. In contrast, between 4 and 20 h, most of the remaining intact LDL and methyl LDL appeared to be irreversibly bound, because it was released at a rate of only 0-1%/h. Thus, we conclude that, under the conditions studied, both reversible and irreversible non-internalized LDL binding play a major role in LDL accumulation by cultured cells.

The QUinapril Ischemic Event Trial (QUIET): evaluation of chronic ACE inhibitor therapy in patients with ischemic heart disease and preserved left ventricular function.

Angiotensin-converting enzyme inhibitors improve endothelial function, inhibit experimental atherogenesis, and decrease ischemic events. The Quinapril Ischemic Event Trial was designed to test the hypothesis that quinapril 20 mg/day would reduce ischemic events (the occurrence of cardiac death, resuscitated cardiac arrest, nonfatal myocardial infarction, coronary artery bypass grafting, coronary angioplasty, or hospitalization for angina pectoris) and the angiographic progression of coronary artery disease in patients without systolic left ventricular dysfunction. A total of 1,750 patients were randomized to quinapril 20 mg/day or placebo and followed a mean of 27 +/- 0.3 months. The 38% incidence of ischemic events was similar for both groups (RR 1.04; 95% confidence interval 0.89 to 1.22; p = 0.6). There was also no significant difference in the incidence of patients having angiographic progression of coronary disease (p = 0.71). The rate of development of new coronary lesions was also similar in both groups (p = 0.35). However, there was a difference in the incidence of angioplasty for new (previously unintervened) vessels (p = 0.018). Quinapril was well tolerated in patients after angioplasty with normal left ventricular function. Quinapril 20 mg did not significantly affect the overall frequency of clinical outcomes or the progression of coronary atherosclerosis. However, the absence of the demonstrable effect of quinapril may be due to several limitations in study design.