Vaporized D-limonene selectively mitigates the acute anxiogenic effects of Δ9-tetrahydrocannabinol in healthy adults who intermittently use cannabis.

BACKGROUND: Cannabis contains hundreds of chemical constituents beyond delta-9-tetrahydrocannabinol (THC), which is believed to drive most of its acute pharmacodynamic effects. The entourage effect theory asserts that non-THC constituents can impact acute cannabis effects, but few empirical studies have systematically evaluated this theory in humans. This study assessed whether the cannabis terpenoid d-limonene mitigates the acute anxiogenic effects of THC. METHODS: Twenty healthy adults completed nine, double-blind outpatient sessions in which they inhaled vaporized THC alone (15mg or 30mg), d-limonene alone (1mg or 5mg), the same doses of THC and d-limonene together, or placebo; a subset of participants (n=12) completed a tenth session in which 30mg THC+15mg d-limonene was administered. Outcomes included subjective drug effects, cognitive/psychomotor performance, vital signs, and plasma THC and d-limonene concentrations. RESULTS: When d-limonene was administered alone, pharmacodynamic outcomes did not differ from placebo. Administration of 15mg and 30mg THC alone produced subjective, cognitive, and physiological effects typical of acute cannabis exposure. Ratings of anxiety-like subjective effects qualitatively decreased as d-limonene dose increased and concurrent administration of 30mg THC+15mg d-limonene significantly reduced ratings of "anxious/nervous" and "paranoid" compared with 30mg THC alone. Other pharmacodynamic effects were unchanged by d-limonene. D-limonene plasma concentrations were dose orderly, and concurrent administration of d-limonene did not alter THC pharmacokinetics. CONCLUSIONS: D-limonene selectively attenuated THC-induced anxiogenic effects, suggesting this terpenoid could increase the therapeutic index of THC. Future research should determine whether this effect extends to oral dose formulations and evaluate the interactions between other cannabis terpenoids or cannabinoids and THC.

Coupling of [Formula: see text] and [Formula: see text] kinetics: insights from multiple exercise transitions below the estimated lactate threshold.

During a step-change in exercise power output (PO), ventilation ([Formula: see text]) increases with a similar time course to the rate of carbon dioxide delivery to the lungs ([Formula: see text]). To test the strength of this coupling, we compared [Formula: see text] and [Formula: see text] kinetics from ten independent exercise transitions performed within the moderate-intensity domain. Thirteen males completed 3-5 repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100, and 120 W on a cycle ergometer. Preceding the ∆40 W step transitions from 60, 80, 100, and 120 W was a 6 min bout of 20 W cycling from which the transitions of variable ∆PO were examined. Gas exchange ([Formula: see text] and oxygen uptake, [Formula: see text]) and [Formula: see text] were measured by mass spectrometry and volume turbine. The kinetics of the responses were characterized by the time constant (τ) and amplitude (Δ[Formula: see text]/Δ[Formula: see text]). Overall, [Formula: see text] kinetics were consistently slower than [Formula: see text] kinetics (by ~ 45%) and τ[Formula: see text] rose progressively with increasing baseline PO and with heightened ∆PO from a common baseline. Compared to τ[Formula: see text], τ[Formula: see text] was on average slightly greater (by ~ 4 s). Repeated-measures analysis of variance revealed that there was no interaction between τ[Formula: see text] and τ[Formula: see text] in either the variable baseline (p = 0.49) and constant baseline (p = 0.56) conditions indicating that each changed in unison. Additionally, for Δ[Formula: see text]/Δ[Formula: see text], there was no effect of either variable baseline PO (p = 0.05) or increasing ΔPO (p = 0.16). These data provide further evidence that, within the moderate-intensity domain, both the temporal- and amplitude-based characteristics of V̇E kinetics are inextricably linked to those of [Formula: see text].

Carbonyl Compounds in Mainstream Smoke of Hemp Cigarettes.

Introduction: CBD is a major phytocannabinoid in hemp (Cannabis sativa containing less than 0.3% THC). Hemp cigarettes are a combustible form of hemp consisting of dried and smokable flowers, which represent 2% of the overall CBD market, and the market is expected to grow. Combustion and pyrolysis of organic material are associated with the production of carbonyl compounds, which are known toxicants and are associated with adverse health outcomes. Concentrations of carbonyl compounds in mainstream hemp cigarette smoke are unknown. Materials and Methods: We analyzed and compared carbonyl concentrations in the mainstream smoke produced by a hemp cigarette (Brand B), a premium hemp cigarette (Brand A), Marlboro Red tobacco cigarette, and a research reference tobacco cigarette using high-performance liquid chromatography. We measured carbonyl concentrations in µg per puff and mg per cigarette. Carbonyls investigated were formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, 2-butanone, and butyraldehyde. Significance was determined using Tukey's test. Results: We observed that Brand B had significantly higher butyraldehyde than any cigarette. No significant differences were observed in crotonaldehyde concentration in the cigarettes. For the remaining carbonyls, Brand A had consistently lower concentrations in mainstream smoke than tobacco cigarettes. Hemp cigarettes emit carbonyls in a lower concentration in µg/puff than tobacco cigarettes, but the magnitude of significance generally decreases when normalized to mg/cigarette. Conclusions: Smoke from hemp cigarettes contains carbonyls at biologically significant concentrations. Opportunities may exist to reduce carbonyl production in these products, and identified potential risks must be considered when balancing the harms and benefits of hemp cigarettes when used for therapeutic purposes.

Electronic nicotine delivery system design and aerosol toxicants: A systematic review.

BACKGROUND: Electronic nicotine delivery systems (ENDS; e-cigarettes), consisting of a battery, heating element and e-liquid, have evolved significantly with wide variation in design, components, operating powers, and chemical constituents. Generated aerosols have been reported to contain potentially toxic substances. We conducted a systematic review to assess what is known about the presence of toxicants in ENDS aerosols in order to inform how system design could mitigate risk. METHODS: Articles reporting on or evaluating design characteristics of ENDS and aerosol constituents were included and summarized. RESULTS: The search identified 2,305 articles, of which 92 were included after full-text review. Findings were grouped into 6 major categories of potentially harmful chemicals: carbonyls, volatile organic chemicals, trace elements, reactive oxygen species and free radicals, polycyclic aromatic hydrocarbons, and tobacco-specific nitrosamines. In general, higher concentrations of aerosol toxicants are associated with increased power or voltage. Aerosol toxicants are also associated with e-liquid flavoring agents existing as primary ingredients or as products of thermal degradation. CONCLUSIONS: Improved ENDS design can reduce toxicant levels. Additional research is needed to develop a framework for optimizing system characteristics to minimize exposure, especially with respect to heating power and e-liquids. Both manufacturers and regulatory agencies have roles in reducing toxicants and potential health risks from ENDS.

Evolutionary Action Score of TP53 Coding Variants Is Predictive of Platinum Response in Head and Neck Cancer Patients.

TP53 is the most frequently altered gene in head and neck squamous cell carcinoma (HNSCC), with mutations occurring in over two thirds of cases; however, the predictive response of these mutations to cisplatin-based therapy remains elusive. In the current study, we evaluate the ability of the Evolutionary Action score of TP53-coding variants (EAp53) to predict the impact of TP53 mutations on response to chemotherapy. The EAp53 approach clearly identifies a subset of high-risk TP53 mutations associated with decreased sensitivity to cisplatin both in vitro and in vivo in preclinical models of HNSCC. Furthermore, EAp53 can predict response to treatment and, more importantly, a survival benefit for a subset of head and neck cancer patients treated with platinum-based therapy. Prospective evaluation of this novel scoring system should enable more precise treatment selection for patients with HNSCC.

Gain-of-function mutant p53 promotes cell growth and cancer cell metabolism via inhibition of AMPK activation.

Many mutant p53 proteins (mutp53s) exert oncogenic gain-of-function (GOF) properties, but the mechanisms mediating these functions remain poorly defined. We show here that GOF mutp53s inhibit AMP-activated protein kinase (AMPK) signaling in head and neck cancer cells. Conversely, downregulation of GOF mutp53s enhances AMPK activation under energy stress, decreasing the activity of the anabolic factors acetyl-CoA carboxylase and ribosomal protein S6 and inhibiting aerobic glycolytic potential and invasive cell growth. Under conditions of energy stress, GOF mutp53s, but not wild-type p53, preferentially bind to the AMPKα subunit and inhibit AMPK activation. Given the importance of AMPK as an energy sensor and tumor suppressor that inhibits anabolic metabolism, our findings reveal that direct inhibition of AMPK activation is an important mechanism through which mutp53s can gain oncogenic function.

Size at birth and autonomic function during psychological stress.

Small size at birth is associated with exaggerated blood pressure responses to psychological stressors, which increase the risk of developing sustained hypertension in adult life. Explanatory mechanisms for this association are not well characterized. We investigated the hypothesis that an adverse fetal environment, reflected by small size at birth, persistently alters autonomic nervous system and baroreflex control of cardiovascular function, resulting in exaggerated blood pressure and heart rate responses to stressors. Men and women from an Australian prospective cohort study underwent a series of 3 psychological stressors (Stroop, mirror-tracing, and speech) while their blood pressure was recorded continuously using a Portapres. Indices of autonomic function were derived using spectrum analysis (wavelet packet transform), and baroreflex function was estimated using an adaptive autoregressive model. We found that women who were small at birth demonstrated increased levels of low-frequency blood pressure variability at rest (r=-0.28; P<0.05) and during stress (r=-0.42; P<0.001), reduced levels of high-frequency heart period variability (r=0.22; P<0.05), and reduced baroreflex sensitivity (r=0.34; P<0.01). These findings were not present in the men. This study provides evidence that markers of impaired fetal growth are related to autonomic cardiovascular control involving modulation of both sympathetic and parasympathetic function but in a sex-specific manner. We also provide the first human evidence of a relationship between size at birth and baroreflex function.

Size at birth and cardiovascular responses to psychological stressors: evidence for prenatal programming in women.

BACKGROUND: Epidemiological studies have repeatedly shown inverse associations between size at birth and blood pressure in later life. There is some evidence to suggest that exaggerated blood pressure responses to psychological stressors are a forerunner of sustained hypertension. OBJECTIVE: To determine whether individuals who were smaller at birth have greater blood pressure and heart rate responses to psychological stressors. DESIGN: Prospective cohort study. METHODS: A total of 104 men and 79 women (mean age 26.3 years) were recruited from the Adelaide Family Heart Study cohort. Blood pressure was monitored continuously throughout the study using a Portapres and participants undertook a series of three stress tests: Stroop, mirror drawing and public speech. The stress response was defined as the increment from baseline to the mean blood pressure during the three tasks. RESULTS: In women, a 1 kg increase in birthweight was associated with an 8.7 mmHg (95% confidence interval: 3.6-13.8, P = 0.001) reduction in the systolic and a 4.1 mmHg (1.6-6.6, P = 0.002) reduction in the diastolic response to stress. The heart rate response to stress was also inversely related to birthweight. These results remained significant after correction for gestational age and other potential confounding factors. Similar results were found for birth length and head circumference. There were no such relationships in men. CONCLUSIONS: This study provides the first human evidence that cardiovascular responses to psychological stressors may be programmed antenatally and suggests a potential mechanism linking reduced fetal growth with raised blood pressure and cardiovascular disease in later life.

Central hypothalamic-pituitary-adrenal activity and the metabolic syndrome: Studies using the corticotrophin-releasing hormone test.

A number of studies have suggested that the metabolic syndrome (principally, the combination of hypertension, glucose intolerance, and dyslipidemia) is associated with subtle dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis leading to raised circulating cortisol concentrations. The mechanisms underlying these observations are not known. We assessed the salivary cortisol response to awakening and pituitary-adrenal responses during a 100-microg human corticotrophin-releasing hormone (CRH) test and a dexamethasone-suppressed CRH test in a well-characterized group of 65-year-old men (n = 122). In the cohort from which this subgroup was drawn, there were associations between the components of the metabolic syndrome and 9 am cortisol concentration in line with previous studies. However, there were no significant associations between blood pressure, glucose tolerance, and lipid concentrations and the dynamic tests of HPA activity. We therefore found no evidence to suggest that exaggerated pituitary responsiveness or increased central drive to the pituitary, as determined by CRH testing, plays a part in the development of the metabolic syndrome.

Fetal programming of the hypothalamic-pituitary-adrenal (HPA) axis: low birth weight and central HPA regulation.

Fetal programming of the hypothalamic-pituitary-adrenal (HPA) axis has been proposed as an intermediary in the association between reduced fetal growth and adult cardiovascular and metabolic diseases. Previous studies have shown that small size at birth is associated with increased fasting plasma cortisol and adrenal responsiveness to ACTH stimulation. We have extended these studies by evaluating the salivary cortisol response to awakening and plasma ACTH and cortisol responses to CRH stimulation and a dexamethasone-suppressed CRH (DEX/CRH) test in a group of low birth weight [LBW; <3.18 kg (7 lb), n = 58] and high birth weight [>3.86 kg (8.5 lb), n = 65] men aged 60-69 yr. Despite no difference in basal pituitary-adrenal activity or in their ACTH and cortisol responses to CRH, LBW men had significantly lower pituitary-adrenal responses in the DEX/CRH test. Although these findings do not explain the HPA abnormalities associated with LBW in previous studies, they provide further evidence of dysregulation of the HPA axis in people who were small at birth.

Cortisol and the metabolic syndrome in South Asians.

OBJECTIVE: The cardiovascular risk factors which comprise the metabolic syndrome are associated with increased hypothalamic-pituitary-adrenal axis (HPAA) activity in some Caucasian populations. South Asians have high rates of cardiovascular disease and its risk factors. We have investigated the relationships between HPAA activity, adiposity and the metabolic syndrome in a South Asian population. DESIGN: Cross-sectional cohort study. PARTICIPANTS: A total of 509 men and women born at the Holdsworth Memorial Hospital, Mysore, South India between 1934 and 1954 and still living in the area. MEASUREMENTS: Fasting 09.00 h cortisol and corticosteroid-binding globulin. The cohort had previously been investigated for features of the metabolic syndrome. RESULTS: At 09.00 h, cortisol concentration was strongly associated with systolic and diastolic blood pressure (r = 0.25 and r = 0.24, respectively; P < 0.001), fasting glucose concentration (r = 0.26; P < 0.001), insulin resistance (r = 0.20; P < 0.001) and fasting triglyceride concentration (r = 0.17; P < 0.001). In general, higher cortisol concentrations added to the effect of adiposity in increasing cardiovascular risk factors, but there was evidence of an interaction between cortisol and adiposity in determining fasting glucose concentration (P = 0.045) and insulin resistance (P = 0.006). CONCLUSIONS: Associations between 09.00 h cortisol concentration and cardiovascular risk factors in this South Asian cohort were stronger than those previously shown in Caucasian populations, despite similar mean cortisol concentrations, and were amplified by adiposity. This suggests that increased glucocorticoid action may contribute to ethnic differences in the prevalence of the metabolic syndrome, particularly among men and women with a higher body mass index.