Another well-known issue in lipidomics is that various sources of contamination can originate artifacts

It is particularly surprising that we see no effect on narcotics, considering most medical marijuana patients specifically use cannabis as a substitute for narcotics. An explanation for this can be that some medical marijuana users do not use for medical reasons many of the MMIC holders in this particular data base may only use for recreational purposes. To observe any further substitution effects, I used Equation 5.7 to regress alcohol induced crude rates, drug-induced crude rates, and all other crude rates on MMICs and unemployment still controlling for county and year fixed effects. Unlike the arrest rate data, no substitution effects were found. Referring to the regression output in Table 5.9 for alcohol-induced deaths, MMICs actually had a statistically significant positive effect on alcohol related deaths. The interpretation is that for every new medical marijuana user, the alcohol crude rate increases by 0.0068 deaths per 100,000. However, observing that zero is in the confidence interval and that the t-statistic is borderline significant, it is likely that there is no effect at all. While this is still a positive number, its suggested effect is so small, it becomes negligible. This can be determined by looking at the average crude rate for alcohol related deaths, which is 15.8. There would have to be an additional 147 MMICs per 100,000 to increase this crude rate by 1 death per 100,000. This is a highly unlikely scenario,plant grow table and could therefore be dismissed. By applying this same model to drug-related deaths, we again get a statistically significant positive effect on the crude rate, shown in Table 5.10.

While this would typically suggest that marijuana is a complement drug to other drugs, the effect is again, miniscule. With the average drug-induced crude rate of 13.4 deaths per 100,000, the number of medical marijuana cardholders would have to increase by 142 to cause 1 drug-related death. Similar to the effect on alcohol-induced mortality rates, this is a very unlikely event, and can be disregarded. While the drug and alcohol related deaths were affected slightly by medical marijuana, all other crude rates did not. There was no statistically significant effect when applying Equation 5.7 to all other crude rates. Fatty acid ethanolamides are a family of endogenous lipid mediators, whose chemical structures consist of a fatty acid moiety bound to ethanolamine by an amide linkage. These compounds are synthesized by cells throughout the body and control inflammation, appetite and food intake, learning and memory, and pain among other functions.1 Palmitoylethanolamide and oleoylethanolamide suppress inflammation by activating the ligand-operated transcription factor, peroxisome proliferator-activated receptor-a.Anandamide acts as a partial agonist at cannabinoid receptor type 1 and 2 receptors and, therefore, belongs to the diverse family of lipid signaling molecules called endocannabinoids .Due to their similar physicochemical properties, FAEs and other ECBs, such as 2-arachidonoyl-snglycerol , are usually coextracted from biological samples.The procedure for their analysis includes extraction with organic solvents followed by purification through solid-phase extraction and subsequent quantitation by liquid chromatography–mass spectrometry or gas chromatography–mass spectrometry .FAEs are present in blood serum or plasma in the pmol per mL scale and in biological tissues in concentration ranging from the pmol to nmol per gram scale. A review of the literature, however, reveals that data from different laboratories, reporting concentration of FAEs in human serum from healthy subjects, often do not corroborate one another. In particular, reported levels of PEA and OEA in serum or plasma of healthy human subjects differ by up to two orders of magnitude, from 5 to 30 pmol per mL6–17 up to 200 pmol per mL of serum or plasma.

During the validation process of a new method for LC/MS analysis of FAEs and ECBs in human serum extracts, we observed unexpectedly high levels of PEA, as compared with data previously obtained in our laboratory.We suspected that these abnormal levels could be due to a recurrent contamination. We found that 5”Pasteur pipettes of most, if not all, commercial brands, contain multiple contaminants detectable by LC/MS, including readily detectable quantities of a compound indistinguishable from PEA.A contaminant that is undistinguishable from PEA is present in glass Pasteur pipettes in amounts that are sufficient to interfere with analysis of biological samples. The contaminant was identified based on its LC retention time, accurate mass, and MS/MS fragmentation pattern, which were identical to those of authentic PEA. By contrast, only a negligible PEA contamination was found in 9” Pasteur pipettes. Furthermore, we isolated the PEA contamination to the polyurethane foam used to package the pipettes, which is transferred to glass pipettes by contact. In line with this finding, Oddi et al.22 recently reported that FAEs can be absorbed by plastic materials during laboratory assays. It is therefore conceivable that FAEs incidentally absorbed by plastics during industrial processes can be released later in organic solvents. Lastly, no other commonly analyzed FAEs or monoacylglycerols were found to be present in the pipettes. We published GC/MS23 and LC/MS5 analytical methods for the quantitation of ECBs and other related FAEs and monoacylglycerols in biological samples, including human serum.Prompted by the need for a novel quantitative LC/MS method to analyze ECBs in blood, we reviewed the literature and noticed discrepancies in the reported concentrations of FAEs and ECBs in human blood serum and plasma . The EC50 for anandamide and 2AG vary depending upon assay and tissue; however, it is important to note that levels reported in Table 1 for both compounds in plasma/serum are below the apparent biologically active concentrations required to activate CB receptors . Regarding relative levels of PEA and OEA, a number of studies reported very similar concentrations for both compounds,whereas others reported PEA approximately twice higher than OEA.Regarding absolute values, two separate laboratories reported levels of PEA and OEA in plasma that were excessively high,which reached or exceeded the concentrations needed by these ligands to engage PPAR-a as agonists. PEA and OEA are, in fact, considered high-potency ligands of PPAR-a; in heterologous expression systems, these FAEs engage the receptor with median effective concentration values of 0.12 lM for OEA and 3 lM for PEA.In the abovementioned reports,although PEA levels did not exceed the EC50, levels of PEA were high relative to other reports.The steady-state concentrations of FAEs in plasma/serum of healthy individuals possibly reflect an equilibrium of ECBs released by peripheral tissues and their enzymatic degradation in the blood stream. In animal tissues , levels of PEA and OEA are present in the same order of magnitude; therefore, it was predictable to find a similar pattern in human serum or plasma, as also shown by the literature reports in Table 1. Surprisingly, in our preliminary experiments, the measured level of OEA was in agreement with most literature reports, whereas PEA was one order of magnitude higher than expected . This finding prompted us to carefully screen all possible sources of contamination, including solvents, reagents, and glassware used for lipid extraction and quantitative analysis. In this study, we identify glass Pasteur pipettes used to transfer solvents and lipid extracts as the source of PEA contamination. The contaminant was identified as PEA by its exact mass and RT in three similar but different chromatographic systems, as well as by its MS2 fragmentation pattern, which were identical to those of standard PEA. Furthermore, we show that PEA is present in the polyurethane foam that manufacturers use to wrap the pipettes before packing, from which it leaks onto the glass pipettes. Moreover, accurate exact mass measurements with ppm deviation lower than five unambiguously confirmed the identity of the contaminant as PEA. Quantitative assessment showed that the content of PEA is 33.4 – 4.02 pmol per pipette. Unfortunately, none of the various manufacturers, whose pipettes were tested, provides 5”3 4 glass Pasteur pipette that are contaminant free . Only 9” pipettes from one vendor were free of PEA traces , allowing the use of these consumables in the overall procedure. The field of lipidomics is rapidly developing; however, reproducible standard procedures across laboratories are not established. Therefore, it is not uncommon for lipidomics data to differ among from independent laboratories.It is generally thought that these discrepancies are a result of the use of different instruments for lipid analysis, as well as differing extraction and separation protocols. In this study, however, all results were confirmed by two independent laboratories using different LC systems and QQQ mass spectrometers . Furthermore, accurate mass data were acquired on a third Shimadzu IT-TOF High-Resolution Mass Spectrometer for definitive confirmation that the contaminant was indeed PEA.Lipids, especially fatty acids, are common contaminants in detergents, mineral oils, greases, and plasticizers; hence, they are often present in laboratory equipment, including glassware and solvents. As shown in this study, assessment of FAEs, a group of lipids with diverse signaling properties, is not sheltered from this pitfall. We have shown that glass Pasteur pipettes,hydroponic table commonly used in lipidomic laboratories to transfer lipid extracts and organic solvents, can contain PEA as contaminant. This contamination gives rise to artifacts in the measurement of PEA in biological samples, especially when the procedure for sample preparation includes fractionation of the lipid extract, which concentrates the contaminant. The scope of this study is an alert to the ECB and FAE scientific community about possible PEA analytical artifacts and thus, great care is needed to exclude the possibility of contaminants when analyzing endogenous PEA levels in biological tissues.Heavy and problematic alcohol use is highly prevalent among HIV-infected individuals, with estimates of use documented as high as 63 % among HIV clinic patients. Indeed, the rate of alcohol use disorders among HIV infected individuals is markedly higher than that observed in the general population.Importantly, both HIV and problematic alcohol use have significant implications for memory functioning, which is vital to successful adherence to complicated medication regimens and effectiveness of cognitive and behavioral interventions for HIV. Although previous research has shown that heavy alcohol use is associated with a host of negative HIV health outcomes, including poor medication adherence, increased immune suppression, reduced effectiveness of therapeutic regimens, faster HIV disease progression, lower survival rates, and worse health-related quality of life, less is known about its impact on self-reported memory functioning and HIV symptom severity. Further, greater HIV symptom burden is associated with reduced health-related quality of life, an outcome that has gained increased significance as treatments for HIV infection have improved. Thus, in order to provide a richer clinical conceptualization to inform intervention and treatment efforts, it is important to determine how problematic alcohol use impacts these domains in this already vulnerable population. HIV disease progression poses significant risk for compromised cognitive efficiency and memory functioning, and although antiretroviral therapy can reduce neurocognitive impairment, mild forms still persist in a large proportion of individuals with HIV. Of note, cognitive impairment, and memory dysfunction more specifically, is associated with worse treatment outcomes among HIV-infected individuals and is known to reduce the effectiveness of interventions aimed at optimizing adherence and reducing risk behavior. Memory dysfunction has also been observed among individuals with heavy drinking and alcohol use disorders and these changes can persist even following an extended period of abstinence. The effects of alcohol on memory varies substantially across social drinkers and chronic alcoholics, and mild neurocognitive deficits are more notable at heavier drinking levels . These independent bodies of research suggest that the combination of problematic alcohol use and HIV may exert a negative additive or synergistic effect on neuropsychological indices of memory functioning. However, the literature speaking to these associations is mixed. Compared to healthy controls and participants with a single diagnosis, individuals with co-occurring HIV and alcohol dependence or abuse have been shown to perform worse on measures of immediate and delayed memory [WMS-R;], and on selective memory processes . In contrast, Rothlind et al. did not observe differences on measures of verbal and visual learning and memory in a comparison of light/non-drinking and heavy drinking HIV-infected individuals. Similarly, no differences in verbal or non-verbal memory emerged in a comparison of HIV-infected and HIV-uninfected African Americans with no drinking and light, moderate and heavy drinking. Finally, no differences in learning and memory were observed in a comparison of HIV positive and HIV negative males with and without a history of alcohol abuse.

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