The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.
[ HUMOR] Filosofia y Testing
The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).
The goal of this paper is to discuss common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor, considering their properties, advantages and limitations in drug testing. In addition, some of the recent studies based on the application of these matrices in the analysis of classic drugs and novel psychoactive substances (NPS) will be reviewed. Other less frequently reported biological specimens are also briefly discussed.
Hair analysis is of great interest in forensic, clinical and analytical sciences and the most common applications in routine analysis include workplace drug testing, drug-facilitated crime, child custody, in utero drug exposure, monitoring abstinence to drugs and/or ethanol and others [71, 73]. Therefore, hair is an alternative biological sample of large importance in forensic toxicology that allows an evaluation of historic drug use/exposure, depending on the hair length.
Vitreous humor (VH) is an alternative matrix commonly used in postmortem toxicological analyses and its application in forensic analysis started in the 1960s [149]. Since then, many analyses in VH have been conducted, including ethanol, illicit drugs and endogenous compounds [150]. One of the interests of using VH in toxicological analysis is especially when traditional matrices, such as blood or urine, are unavailable or under inappropriate conditions for analysis [151]. Casework involving embalmed, burned or highly decomposed bodies are such examples [152].
The application of VH in forensic analyses is based on several advantages of this matrix. In comparison to other postmortem fluids, the composition of VH makes it a cleaner matrix, with less interferents [2, 153], being an aqueous matrix with minimal protein contents [151]. VH also has a low number of cells and lacks of blood vessels [153], avoiding potential infections from the blood [155]. Another advantage of VH is its prolonged stability in comparison to other matrices [2, 156]. The location of VH is also an advantage, as it is located in a body compartment protected against contamination and microbial activity [149, 151], especially being remotely located from gastrointestinal tract [150]. In comparison, postmortem blood is more likely than VH to suffer microbial activity and degradation [157] and autolytic processes are delayed in VH in relation to blood [158]. After death, bacteria present in the gut, lung, oral cavity and other microbiomes, and also environmental bacteria may infect other surrounding tissues and fluids, whereas in VH this process occur to a lesser extent, reducing the contamination and increasing the stability of this specimen [149]. For example, in a study by Harper [157], postmortem blood and VH were collected from 51 decedents and microbiological analyses revealed no significant amounts of bacteria or fungi in VH and high diversity of microorganisms in 32 postmortem blood specimens. This is particularly interesting for ethanol testing, since the postmortem formation of ethanol is unlikely in VH [159]. In VH, there is no esterase activity [160], which also contributes to an increased stability of compounds in this specimen. Although the use of VH has several analytical benefits, drug testing in VH has a few limitations. The volume available for sampling is limited and the blood-retinal barrier may restricts the incorporation of drugs into VH [156, 159]. In addition, in violent death cases a rupture of the eyeball may occur, with loss of VH.
Over the years, VH has been successfully used in forensic casework, for illicit drugs and NPS testing. Several classic drugs of abuse have been detected in authentic VH specimens such as the following examples: ethanol [159, 181, 190], cocaine and its metabolites [155, 164, 166, 172, 176, 181, 190,191,192], opioids and/or their metabolites [155, 167, 168, 173, 176, 177, 182, 185, 190], amphetamine and/or methamphetamine [164, 173, 190], MDA derivatives [169], ketamine [172], phencyclidine [154, 170], LSD and its metabolites [175], γ-hydroxybutyric acid [193], benzodiazepines [171, 173, 184, 190], antidepressants [173, 180, 194, 195] and barbiturates [196]. On the other hand, VH does not seem to be a good biological matrix for investigating cannabinoids [151]. In a study by Saenz et al. [197], THC and THC-OH were detected only in blood and/or urine but not in VH in two cases [197]. In these same two cases, THC-COOH was detected in blood, urine and VH in one case whereas in the other case THC-COOH was detected in blood and urine only [197]. Similarly, in another study by Peres et al. [164], THC and THC-COOH were detected in three cases in whole blood specimens but not in VH. Other studies in the literature reported findings regarding THC and its metabolite distribution into VH in agreement with these observations [170, 198]. This can be rationalized due to strong affinity for plasma proteins and lipophilicity exhibited by THC, which reduces the incorporation of THC into aqueous specimens, such as VH [164, 199]. In addition, Lin and Lin [198] observed low vitreous concentrations of THC-COOH, a hydrophobic character compound. In regard to NPS, VH has also been implemented in toxicological analysis for a different classes including fentanyl and non-fentanyl opioids [200,201,202,203,204,205,206,207], synthetic cathinones [208,209,210,211,212], designer benzodiazepines [190], 5-(2-aminopropyl)indole [213] and phenethylamines [214,215,216].
The selection of specimens in toxicological analyses is a critical step. Understanding the properties of both target analyte and matrix is very important, to select the most appropriate biological fluid/tissue for the case under investigation. Alternative biological matrices are biological fluids/tissues that can provide additional information and advantages in comparison to blood and urine testing, in several aspects such as sample collection, detection window and complexity of sample preparation/analysis. In addition, these matrices can be collected and analyzed when blood and urine are not available. However, each one of these alternative matrices has its own characteristics, advantages and limitations, which need to be considered. The perspective in forensic toxicology is that alternative matrices will be more frequently explored in the future. For example, the Organization of Scientific Area Committees for Forensic Science (OSAC) recommend research on alternative matrices for the improvement of forensic toxicology [225]. Therefore, further research is still needed to provide analytical methods and better understanding on the behavior of drugs in these matrices, especially for emerging NPS.
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OBJECTIVOS: investigar la relación entre quejas psicológicas y prevalencia de consumo de drogas entre universitarios atendidos en núcleo de asistencia psicológica. METODOLOGÍA: se realizó un levantamiento en una universidad paulista, sobre las quejas que motivaron la búsqueda por el servicio de Psicología y el patrón de consumo de drogas informado por la clientela. RESULTADOS: entre 165 estudiantes evaluados, el 76,4% son del sexo femenino. Las principales quejas fueron relacionadas con el humor depresivo y las dificultades en la esfera de las relaciones afectivas, sociales y familiares. El porcentaje de los que informaron consumir marihuana fue mayor, entre participantes con quejas de humor depresivo, dificultades en relaciones interpersonales y conductas del espectro suicida, en comparación con estudiantes sin esas quejas. CONCLUSIÓN: los programas de carácter preventivo y / o terapéutico podrían promover mejoras en la calidad de vida de esa población. 2ff7e9595c
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