Helen Poulsen

Bio: Helen Poulsen is an academic researcher. The author has contributed to research in topics: Analyte & Colloidal gold. The author has an hindex of 2, co-authored 2 publications receiving 63 citations.

The results of an experimental indoor hydroponic Cannabis growing study, using the 'Screen of Green' (ScrOG) method-Yield, tetrahydrocannabinol (THC) and DNA analysis.

Abstract: The results of an indoor hydroponic Cannabis growth study are presented. It is intended that this work will be of assistance to those with an interest in determining an estimation of yield and value of Cannabis crops. Three cycles of six plants were grown over a period of 1 year in order to ascertain the potential yield of female flowering head material from such an operation. The cultivation methods used were selected to replicate typical indoor hydroponic Cannabis growing operations, such as are commonly encountered by the New Zealand Police. The plants were also tested to ascertain the percentage of the psychoactive chemical Δ-9 tetrahydrocannabinol (THC) present in the flowering head material, and were genetically profiled by STR analysis. Phenotypic observations are related to the data collected. The inexperience of the growers was evidenced by different problems encountered in each of the three cycles, each of which would be expected to negatively impact the yield and THC data obtained. These data are therefore considered to be conservative. The most successful cycle yielded an average of 881g (31.1oz) of dry, groomed female flowering head per plant, and over the whole study the 18 plants yielded a total of 12,360g (436.0oz), or an average of 687g (24.2oz) of dry head per plant. THC data shows significant intra-plant variation and also demonstrates inter-varietal variation. THC values for individual plants ranged from 4.3 to 25.2%. The findings of this study and a separate ESR research project illustrate that the potency of Cannabis grown in New Zealand has dramatically increased in recent years. DNA analysis distinguished distinct groups in general agreement with the phenotypic variation observed. One plant however, exhibiting a unique triallelic pattern at two of the five loci tested, while remaining phenotypically indistinguishable from three other plants within the same grow.

The incidence of alcohol and other drugs in drivers killed in New Zealand road crashes 2004–2009

Abstract: Alcohol is a drug known to impair the ability to drive safely and is acknowledged as a major factor in New Zealand road crashes [1] . However, the use of other impairing drugs by New Zealand drivers is largely unknown. This paper reports the prevalence of drug use by drivers killed on New Zealand roads. As this is a biased population sample the results can only indicate possible drug use in the wider driving population. Blood samples taken from 1046 deceased drivers were analysed for the presence of alcohol and a range of both illicit drugs and psychoactive medicinal drugs. Five hundred and forty-six (52%) of these drivers had not used alcohol or other potentially impairing drugs. Five hundred (48%) had alcohol and/or other drugs in their blood that may have impaired their ability to drive safely. Of these 500 drivers, 135 had used alcohol alone, 96 had used cannabis alone and 142 had used a combination of alcohol and cannabis, but no other drug. Alcohol concentrations in 351 drivers who had drunk alcohol ranged from 5 to 354 mg per 100 mL (mean 152 mg/100 mL). Levels of tetrahydrocannabinol (THC) in the blood of the 314 drivers who had used cannabis ranged from approximately 0.1 ng/mL to 44 ng/mL (mean 5.6 ng/mL). There were 127 drivers who had used some other combination of drugs, many still including alcohol and/or cannabis. Only 29 of the 500 drivers who had used a drug, had not used either cannabis or alcohol and 240 (48%) of the 500 drivers had used more than one potentially impairing drug.

Accounting for Interaction Kinetics between Gold Nanoparticles and Aptamers Enables High-Performance Colorimetric Sensors.

Abstract: DNA aptamers have emerged as promising probes for challenging analytes that cannot be easily detected by conventional probes, including small-molecule targets. Among the different signal transduction approaches, gold nanoparticle (AuNP) aggregation assays have been widely used to generate a colorimetric response from aptamer-target interactions. This sensor design relies on the competition between the aptamer adsorbing to the AuNP surface versus interacting with the target, whereby target binding reduces the number of adsorbed aptamers that destabilizes AuNPs toward salt-induced aggregation, thereby inducing a color change. However, this thermodynamic framework overlooks the potential influence of interaction kinetics of different aptamer conformations with AuNP surfaces and with targets in solution or near surfaces. Here, we show that aptamers become more strongly adsorbed on AuNPs over time, and these trapped aptamers are less responsive toward the target analyte. By varying the sequence of addition in sensing assays, we demonstrate that these interaction kinetics have a significant effect on the sensor response and thereby produce an effective sensor for methamphetamine (meth) at biologically relevant levels in oral fluids. Along with underpinning new tools for assay development, this new knowledge also highlights the need for aptamer selection strategies that evolve aptamer sequences based on the functionality that they need to exhibit in an actual sensor.

How Saliva Interferes with Colorimetric Gold Nanoparticle Aptasensors: Understanding and Mitigating Surface Interactions.

Abstract: Colorimetric gold-nanoparticle-based biosensors are an attractive platform for the detection of small-molecule analytes. Taking advantage of the adsorption of DNA aptamer probes on AuNPs, these sensors can be simple, rapid, sensitive, selective, and cost-effective. These properties are important for rapid detection of drugs like methamphetamine in biological matrices. Saliva is a highly desirable matrix for development of diagnostic tests because saliva sampling is minimally invasive and drug levels relate to recent use rather than accumulation from historical use. However, saliva is a complex fluid that presents a multitude of challenges when applying colorimetric aggregation assays. Here, we show that the contents of saliva interfere with the sensor in two main ways: (i) suppressing color change signals due to proteins nonspecifically adsorbing to nanoparticles and (ii) blocking aggregation and generating false signals due to specific electrolytes that induce aggregation. With this knowledge, we examine strategies to mitigate these effects, including sample collection and pretreatment procedures. These measures ultimately result in a sensor that can detect methamphetamine spiked into saliva samples and suggest immense promise for the feasibility of these platforms for on-site diagnostic applications.

Analysis of cannabis seizures in NSW, Australia: cannabis potency and cannabinoid profile.

Abstract: Recent analysis of the cannabinoid content of cannabis plants suggests a shift towards use of high potency plant material with high levels of Δ9-tetrahydrocannabinol (THC) and low levels of other phytocannabinoids, particularly cannabidiol (CBD). Use of this type of cannabis is thought by some to predispose to greater adverse outcomes on mental health and fewer therapeutic benefits. Australia has one of the highest per capita rates of cannabis use in the world yet there has been no previous systematic analysis of the cannabis being used. In the present study we examined the cannabinoid content of 206 cannabis samples that had been confiscated by police from recreational users holding 15 g of cannabis or less, under the New South Wales “Cannabis Cautioning” scheme. A further 26 “Known Provenance” samples were analysed that had been seized by police from larger indoor or outdoor cultivation sites rather than from street level users. An HPLC method was used to determine the content of 9 cannabinoids: THC, CBD, cannabigerol (CBG), and their plant-based carboxylic acid precursors THC-A, CBD-A and CBG-A, as well as cannabichromene (CBC), cannabinol (CBN) and tetrahydrocannabivarin (THC-V). The “Cannabis Cautioning” samples showed high mean THC content (THC+THC-A = 14.88%) and low mean CBD content (CBD+CBD-A = 0.14%). A modest level of CBG was detected (CBG+CBG-A = 1.18%) and very low levels of CBC, CBN and THC-V (<0.1%). “Known Provenance” samples showed no significant differences in THC content between those seized from indoor versus outdoor cultivation sites. The present analysis echoes trends reported in other countries towards the use of high potency cannabis with very low CBD content. The implications for public health outcomes and harm reduction strategies are discussed.

Quantifying cannabis use with the Timeline Followback approach: A psychometric evaluation

Abstract: Background In the absence of a standardized cannabis unit, self-report instruments are inadequate for accurate quantification of cannabis use. The study extends the feasibility of using a cannabis substitute to reliably and validly measure quantity of cannabis use. Method Ninety-eight adult Australian cannabis users ( M age = 27.98, SD = 11.10; 65.31% male) completed a 90-day Timeline Followback interview regarding their cannabis use, utilizing the cannabis substitute Marijuanilla to report on quantity of use. Ninety-two of these individuals completed the interview at two time-points, and 56 of these participants had collaterals corroborate their cannabis use reports. Results Inter-rater reliability was excellent, while test–retest reliability was good to excellent. Intra-class correlation coefficients between participant and collateral reports, while similar to previous research, were unacceptable. Quantity of cannabis use statistically significantly added to frequency of use in predicting cannabis problems and dependence severity. Concurrent and discriminant validity were established with single-item and positive impression management measures, respectively. In addition, Marijuanilla appeared similar to one specimen of street seized cannabis, but not to two others. Importantly, participants’ cravings to use cannabis did not increase as a result of using the cannabis substitute to report on their cannabis use. Conclusions These data suggest that utilizing Marijuanilla to facilitate the reporting of grams of cannabis use may be reliable and valid; however, such comprehensive assessment may only be necessary for clinical trials and epidemiological studies, which rely on precise estimates of cannabis use.

Factors determining yield and quality of illicit indoor cannabis (Cannabis spp.) production

Abstract: Judiciary currently faces difficulties in adequately estimating the yield of illicit indoor cannabis plantations. The latter data is required in penalization which is based on the profits gained. A full factorial experiment in which two overhead light intensities, two plant densities and four varieties were combined in the indoor cultivation of cannabis (Cannabis spp.) was used to reveal cannabis drug yield and quality under each of the factor combinations. Highest yield was found for the Super Skunk and Big Bud varieties which also exhibited the highest concentrations of Δ(9)-tetrahydrocannabinol (THC). Results show that plant density and light intensity are additive factors whereas the variety factor significantly interacts with both plant density and light intensity factors. Adequate estimations of yield of illicit, indoor cannabis plantations can only be made if upon seizure all factors considered in this study are accounted for.

The effect of electrical lighting power and irradiance on indoor-grown cannabis potency and yield.

Abstract: The floral development and potencies [Δ(9) -tetrahydrocannabinol (THC) contents] of cannabis plants were compared when grown indoors under high-pressure sodium lamps consuming electrical power at three densities (270, 400, and 600 W/m(2) ). After a 3-week vegetative phase, plants were grown for 8 weeks, with lamps maintaining an artificial day length of 12 h. Foliar and floral yields were measured. Gas chromatography was used to measure the content of the psychoactive cannabinoid THC. Mean yields per unit of electrical power in each lighting regime ranged from 0.9 to 1.6 g/W, the highest being achieved in the lowest irradiance regime. The individual potencies of the separated leaf and flower materials were not affected by increasing irradiance. However, there was a corresponding increase in the overall potency of the aerial plant tissue. This was because of the plants in brighter conditions producing a higher proportion of floral material. Language: en

The culpability of drivers killed in New Zealand road crashes and their use of alcohol and other drugs

Abstract: Over a period of five years, blood samples were taken from 1046 drivers killed as a result of a motor vehicle crash on New Zealand roads. These were analysed for the presence of alcohol and a range of both illicit drugs and psychoactive medicinal drugs. Driver culpability was determined for all crashes. The control group of drug- and alcohol-free drivers comprised 52.2% of the study population. Drivers positive for psychoactive drugs were more likely to be culpable (odds ratio (OR) 3.5, confidence interval (CI) 95% 2.4–5.2) than the control group. Driver culpability exhibited the expected positive association with alcohol use (OR 13.7, 95% CI 4.3–44) and with combined alcohol and cannabis use (OR 6.9, 95% CI 3.0–16). There was only a weak positive association between cannabis use (with no other drug) and culpability (OR 1.3, CI 95% 0.8–2.3). Furthermore, the OR for drivers with blood tetrahydrocannabinol (THC) concentrations greater than 5 ng/mL was lower (OR 1.0, CI 95% 0.4–2.4) than drivers with blood THC concentrations less than 2 ng/mL (OR 3.1, CI 95% 0.9–10). This is inconsistent with results reported by other studies where a significant increase in crash risk was found with blood THC levels greater than 5 ng/mL. In this study, there were very few drivers who had used a single drug, other than cannabis or alcohol. Therefore, from this study, it is not possible to comment on any relationship between opioid, stimulant or sedative drug use and an increased risk of being killed in a crash for the drivers using these drugs. The results from a multivariate analysis indicate that driver gender, age group and licence status, (P = 0.022, P = 0.016, P = 0.026, respectively), the type of vehicle being driven (P = 0.013), the number of vehicles in the crash (P < 0.001), the blood alcohol concentration of the driver (P < 0.001) and the use of any drug other than alcohol and cannabis (P = 0.044), are all independently associated with culpability.