Vitreous Humor Specimens Research Articles

Cell-Free DNA Extraction of Vitreous and Aqueous Humor Specimens for Diagnosis and Monitoring of Vitreoretinal Lymphoma.

Vitreoretinal lymphoma (VRL) represents an aggressive lymphoma, often categorized as primary central nervous system diffuse large B-cell lymphoma. To diagnose VRL, specimens such as vitreous humor and, more recently, aqueous humor are collected. Diagnostic testing for VRL on these specimens includes cytology, flow cytometry, and molecular testing. However, both cytopathology and flow cytometry, along with molecular testing using cellular DNA, necessitate intact whole cells. The challenge lies in the fact that vitreous and aqueous humor typically have low cellularity, and many cells get destroyed during collection, storage, and processing. Moreover, these specimens pose additional difficulties for molecular testing due to the high viscosity of vitreous humor and the low volume of both vitreous and aqueous humor. This study proposes a method for extracting cell-free DNA from vitreous and aqueous specimens. This approach complements the extraction of cellular DNA or allows the cellular component of these specimens to be utilized for other diagnostic methods, including cytology and flow cytometry.

The interest of using vitreous humor for γ-hydroxybutyrate (GHB) quantification in related fatalities: Stability evaluation, case report and literature review

Analysis and interpretation of the findings for γ-hydroxybutyrate (GHB) in related fatalities remains problematic. Indeed, GHB is a naturally occurring compound present in both the mammalian central nervous system and peripheral tissue. Moreover, a postmortem increase in endogenous GHB concentration has been observed, especially in blood. Facing this issue, the use of an alternative matrix such as vitreous humor (VH) can thus be particularly interesting for GHB testing and quantification. VH is considered to be less prone to postmortem redistribution, is easy to collect, and has relatively few interfering compounds for the analytical process. In this context, the authors report the case of a GHB-related fatality involving 22-year-old male. In this case, GHB femoral blood (FB) (790 mg/L) and vitreous (750 mg/L) concentrations appeared similar with a FB to VH (FB/VH) ratio of 1.05. In addition, other similar cases with both GHB blood and vitreous concentrations were reviewed. Five cases were identified. The blood to VH ratios ranging from 0.13 to 2.58. Finally, GHB stability was documented in postmortem blood and VH, in order to address the reliability of VH as an alternative matrix for GHB quantitation at postmortem. GHB appeared relatively stable in postmortem blood specimens (at 50 mg/L) over a period of 28 days when stored at +4 °C or −20 °C. The same results were observed in VH specimens.

Microbiological study on foreign body and vitreous samples of patients with intraocular foreign body

To evaluate the relationship between the microbiological results of the vitreous humor and those of foreign body specimens in patients with intraocular foreign body (IOFB). Seventy-one patients with an IOFB were included in this descriptive prospective case series. All patients underwent immediate IOFB removal. Vitreous sampling was performed during vitrectomy. Foreign bodies were placed directly into culture media for microbiological study. Thirteen (18.3%) patients developed endophthalmitis. The results of microbiological analysis of IOFB and vitreous humor specimens were negative in nine patients and positive in four. Fifty-eight (81.6%) patients with an IOFB had no evidence of endophthalmitis. Among them, seven patients showed positive microbiological results of foreign bodies with no manifestations of endophthalmitis. In five patients, a Staphylococcus epidermidis strain was observed in the culture of the IOFB specimen. Two patients had only positive smear test results of their vitreous humor specimen. A correlation appears to be present between the microbiological results of the vitreous humor and IOFB specimens in patients with clinical findings of endophthalmitis but not in patients with a pure IOFB without clinical features of endophthalmitis. This may justify early use of intravitreal and intravenous antibiotics before the development of endophthalmitis.

Validation of a New Salt-Assisted HS-GC-FID Method for the Determination of Ethanol in the Vitreous Humor.

Headspace gas chromatography with a flame ionization detector (HS-GC-FID) is a well-established approach for determining blood alcohol concentration, including in cadaveric specimens. Although the integrity of blood specimens can be adequately guaranteed after the sampling, the quantification of ethanol in cadaveric blood can be affected by postmortem fermentative phenomena occurring between the time since death and the sampling of biofluids. The vitreous humor is less affected by putrefactive phenomena allowing compound determination and its use as an alternative biological matrix. The present work aimed to develop and validate a method using the salting-out effect and based on HS-GC-FID for the determination of ethanol in the vitreous humor. The reported analytical method is based on a simple vitreous humor pre-treatment consisting of a dilution (1:9) with a solution of 2.5 mol/L K2CO3 and 0.0012 mol/L tert-butanol (internal standard). After 1 min of incubation, part of the specimen evaporated in the headspace (2,000 µL) is injected into the chromatographic system and analyzed in isothermal mode (40°C), with a chromatographic time of 1.6 min. The method was validated in terms of selectivity, the lowest limit of detection, intraday and total imprecision, and trueness (bias). The determination of ethanol in the vitreous humor and blood was carried out in 75 cases. The correlation between the two matrices was confirmed in 61 cases. However, 14 vitreous humor specimens showed lower ethanol concentrations, and in the related blood specimens, it was possible to identify the signal of n-propanol, a typical product of postmortem microbial fermentation, that justifies the excess of ethanol in the blood specimens.

Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) RNA in the Human Eye

ABSTRACT Purpose To determine the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in postmortem ocular specimens of patients with severe COVID-19 disease. Patients and methods Postmortem conjunctival (28 samples), aqueous humor (30 samples) and vitreous humor (30 samples) specimens were obtained bilaterally from the eyes of 15 deceased COVID-19 patients within one hour of death. The presence of viral RNA was evaluated in samples using Real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Results Positive RT-PCR SARS-COV-2 results were found in one conjunctival and 2 vitreous humor samples. All aqueous humor samples tested negative for the presence of SARS-COV-2 RNA. Of note, three positive samples were obtained from three different patients. The overall prevalence of positive RT-PCR ocular samples was 3.4% among all samples and 20% at the patient level. Conclusion SARS-CoV-2 RNA is detectable in postmortem conjunctival and vitreous humor samples of patients with severe COVID-19.

Cytokine Levels in Human Vitreous in Proliferative Diabetic Retinopathy.

In this study, we compare the vitreous cytokine profile in patients with proliferative diabetic retinopathy (PDR) to that of patients without PDR. The identification of novel cytokines involved in the pathogenesis of PDR provides candidate therapeutic targets that may stand alone or work synergistically with current therapies in the management of diabetic retinopathy. Undiluted vitreous humor specimens were collected from 74 patients undergoing vitrectomy for various vitreoretinal disorders. Quantitative immunoassay was performed for a panel of 36 neuroinflammatory cytokines in each specimen and assessed to identify differences between PDR (n = 35) and non-PDR (n = 39) patients. Levels of interleukin-8 (IL-8), IL-15, IL-16, vascular endothelial growth factor (VEGF), VEGF-D, c-reactive protein (CRP), serum amyloid-A (SAA), and intracellular adhesion molecule-1 (ICAM1) were significantly increased in the vitreous of PDR patients compared to non-PDR patients (p < 0.05). We report novel increases in IL-15 and IL-16, in addition to the expected VEGF, in the human vitreous humor of patients with PDR. Additionally, we confirm the elevation of ICAM-1, VCAM-1, SAA, IL-8 and CRP in the vitreous of patients with PDR, which has previously been described.

Determination of Methadone and Tramadol in Vitreous Humor Specimens Using Dispersive LiquidLiquidMicroextractionandUltraHighPerformance Liquid Chromatography

Background: Drug abuse is spreading rapidly all over the world. Methadone and tramadol are among not only the most abused opioids but also important from the forensic point of view. Therefore, we need to devise a simple and sensitive method for the sample preparation and identification of abused drugs in postmortem specimens. Methods: A simple and rapid Dispersive Liquid-Liquid Microextraction (DLLME) technique coupled with Ultrahigh Performance Liquid Chromatography (UHPLC) was developed for the extraction and analysis of methadone and tramadol from postmortem vitreous humor samples. Different parameters affecting the extraction recovery, such as the type and volume of extraction and dispersion solvents, pH value, sensitivity, and specificity, were optimized and studied. Results: Under optimized conditions, the recovery ranges were 82.3%-89.6% and 85.4%-87.1% for methadone and tramadol, respectively. The linear range was 25-100 ng/mL for both methadone and tramadol with a correlation coefficient (R2) of more than 0.98. Limit of Detection (LoD) and Limit of Quantification (LoQ) were 3 and 8 ng/mL for methadone and 6 and 16 ng/mL for tramadol. The accuracy level of the methods for methadone and tramadol detection were 99.4%-100% and 99.7%-99.9%, respectively. The method was specific enough for the qualitative and quantitative determination of methadone and tramadol. Conclusion: The obtained results showed that DLLME combined with UHPLC is a fast and straightforward method for determining methadone and tramadol in postmortem vitreous humor specimens.

Detection of Drugs in Postmortem Specimens of Blood, Vitreous Humor and Bone Marrow Aspirate.

In case of basic biological materials (blood, urine, vitreous humor) being unavailable, bone marrow can be used for toxicological tests. The aim of the study was to assess the concentration of various xenobiotics in the bone marrow, as well as in the blood and the vitreous humor. The analysis was performed in the biological material originating from the autopsy (n=120), using the LC-MS method and with liquid/liquid extraction at pH=9. As many as 46 different xenobiotics were detected in the biological material, strong correlations between the concentration of a given xenobiotic in blood and bone marrow, as well as in the vitreous humor and bone marrow, were noted for most of them, with the exception of diazepam and 7-aminoclonazepam. The obtained results indicate the possibility of using bone marrow to determine the concentration of numerous xenobiotics in the situation of basic biological materials being unavailable, as well as using the results obtained in the future to better understand the pharmacokinetic processes and the effect of postmortem redistribution on medication and drug concentrations in the body of a deceased person.

Local and systemic production of 45 cytokines in complicated proliferative diabetic retinopaty

Diabetic retinopathy (DR) is multifactorial by its origin, involving many cytokines and growth factors. Studies of cytokine levels in biological fluids seem to be relevant for an in-depth understanding of the disease pathogenesis. The purpose of the work was a comparative analysis of 45 cytokines at systemic (blood serum (BS)) and local (vitreous humor (VH)) levels in the patients with complicated proliferative DR, showing various features of the clinical pattern. The content of cytokines was tested in 53 samples of BS and 32 samples of VH in 53 patients with type 1 and type 2 diabetes mellitus with severe proliferative DR. We used the multiplex analysis technique by means of xMAP platform and Luminex xPONENT 3.1 program using 45-plex sets (Procarta Plex «eBioscience», Austria). 25 cytokines were detected at significant amounts in BS test samples, and 27 cytokines were revealed in VH specimens. Sensitivity limits of the test system allowed to find significantly higher levels of 7 cytokines (IL-6, IL-8, IP-10, MCP-1, HGF, LIF and VEGF-A) in VH samples, than in the BS, thus indicating to their local intraocular production. Correlations between the contents of VEGF-A growth factor and amounts of cytokines, including those involved in inflammatory reactions, are shown in VH, thus presuming the interrelation of pathogenetic components, i.e., inflammation and neoangiogenesis. The features of intraocular cytokine content were determined for various manifestations of diabetic ocular changes. Hemophthalmus has been shown to be associated with increased IL-8 and IP-10; iris rubeosis, with increase in LIF; proliferative DR activity was associated with higher MCP-1 levels, and extremely severe changes were related to increase in IL-6 and EGF. Testing of cytokines in biological fluids is informative when studying the mechanisms of inflammation, neoangiogenesis, and protective responses in pathogenesis of diabetic retinopathy.

Postmortem Fluid Concentrations of Heroin Biomarkers and Their Metabolites.

Only limited data exist concerning the utility of complementary specimens in heroin-related deaths. As such, this report employed a validated LC-MS-MS method to quantify 6-monoacetylmorphine (6-MAM), 6-acetylcodeine (6-AC), and their metabolites morphine and codeine in blood with (BN) and without preservative (B) and the additional unpreserved specimens of vitreous humor, urine, stomach contents, and bile from 20 postmortem cases in which heroin was the primary cause of death. The median concentration of 6-MAM in BN was 0.011mg/L, B was 0.008mg/L, urine was 0.186mg/L, vitreous humor was 0.022mg/L, stomach contents was 0.147mg/L, and bile was 0.012mg/L. Only one case was found to be positive for 6-AC in B (case 6, 0.002mg/L), and the median concentration of 6-AC was 0.002mg/L in BN, 0.012mg/L in urine, 0.003mg/L in vitreous humor, 0.057mg/L in stomach contents, and 0.004mg/L in bile. These findings present new information on the distribution of these analytes in complementary matrices and support their inclusion for accurately determining the role of heroin in opioid-related deaths.

Effects of Vitrectomy and Lensectomy on Older Rhesus Macaques: Oxygen Distribution, Antioxidant Status, and Aqueous Humor Dynamics.

PurposeThe purpose of this study is to evaluate effects of vitrectomy (PPV) and lens extraction with intraocular lens implantation (PE/IOL) on molecular oxygen (pO2) distribution, aqueous humor antioxidant–oxidant balance, aqueous humor dynamics, and histopathologic changes in the trabecular meshwork (TM) in the older macaque monkey.MethodsSix rhesus monkeys underwent PPV followed by PE/IOL. pO2, outflow facility, and intraocular pressure (IOP) were measured. Aqueous and vitreous humor specimens were analyzed for antioxidant status and 8-hydroxy-2′-deoxyguanosine (8-OHdG), a marker of oxidative damage. TM specimens were obtained for immunohistochemical and quantitative PCR analysis.ResultspO2 at baseline revealed steep gradients in the anterior chamber and low levels in the posterior chamber (PC) and around the lens. Following PPV and PE/IOL, pO2 significantly increased in the PC, around the IOL, and angle. IOP increased following both surgical interventions, with no change in outflow facility. Histopathologic analysis did not show changes in TM cell quantification, but there was an increase in 8-OHdG. Quantitative PCR did not reveal significant differences in glaucoma-related gene expression. Aqueous and vitreous humor analysis revealed decreased ascorbate and total reactive antioxidant potential and increased 8-OHdG in the aqueous humor only in the surgical eyes.ConclusionsOxygen distribution in the older rhesus monkey is similar to humans at baseline and following surgical interventions. Our findings of histopathologic changes of TM oxidative damage and alterations in the oxidant-antioxidant balance suggest a potential correlation of increased oxygen exposure with oxidative stress/damage and the development of open angle glaucoma.

Identification of pathgenic bacteria in aqueous and vitreous of endophthalmitis by 16S rDNA sequencing technique

Background Endophthalmitis is a serious complication of intraocular surgery.Conventional identification methods for bacteria are becterial culture and smear method, but these laboratory tests spend a long time and have low positive rates.16S rDNA is the bacterial chromosome encoding ribosomal RNA sequences, and it is determined that 16S rDNA sequencing has a high specificity for the identification of bacteria. Objective This study was to identify the infectious bacteria from aqueous humor or vitreous body in the eyes with endophthalmitis by 16S rDNA sequencing technique, and to investigate the diagnosis efficency of 16S rDNA sequencing technique on bacterial endophthalmitis. Methods Anterior chamber fluid (0.1-0.2 ml) or vitreous humor (0.5-1.0 ml) specimens were collected from 5 eyes of 5 patients with endophthalmitis in Qingdao Eye Hospital from June to December 2015 and used for high throughput sequencing, bacterial culture and smear, respectively.Bacteria DNA was extracted from the specimen with D3096-01 trace DNA kit for the amplification of V3-V4 region of 16S rRNA gene and sequencing of hypervariable region of all microbes in the samples by MiSeq Illumina Sequencing Platform.Then the bioinformatic analysis including analysis of taxonomy, abundance and alpha diversity were performed.Nuclease-free water of 50 μl in the centrifuge tube was used as control. Results Five aqueous humor or vitreous body samples were collected, and the positive results were exhibited by smear examination, with the Gram positive bacilli in the trumatic endophthalmitis eye and Gram negative bacilli in the filtering bleb infectious endophthalmitis eye, and all culture results were negative.16S rDNA squencing showed the positive outcomes in all the 5 samples.The high abundent nacteral genuses were Staphylococcus (65.28%), Streptococcus (18.90%) and Pseudomonas (12.76%) in the trumatic endophthalmitis eye; the major components of sample were Pseudomonas (53.68%), Acinetobacter (8.62%) and Limnobacter (5.96%) in the eye with acute endophthalmitis occurring at 2 days following cataract surgery; the major components in the filtering bleb infectious endophthalmitis eye were Moraxella (88.89%) and Pseudomonas (9.52%); the Pseudomonas was major components in the later-onset endophthalmitis eye (84.63%) and the eye with acute endophthalmitis occurring at 1 day after cataract surgery (97.89%). Conclusions A distinct advantage is found in 16S rDNA sequencing technique for the indentification of the pathogenic bacteria in endophthalmitis eyes due to its high positive rate in comparison with bacterial culture and smear method. Key words: Endophthalmitis/microbiology; Aqueous humor/microbiology; Vitreous body/microbiology; DNA, bacterial/analysis; Sequence analysis, DNA; 16S rDNA

Real-time near-body drug screening during autopsy I: use of the Randox biochip drugs of abuse DOA I and DOA II immunoassays

Screening for drugs of abuse is widely employed as part of forensic toxicology investigations. The nature of specimens collected at autopsy varies depending on local customs, the case circumstances, and the condition of the cadaver. It is generally accepted that wherever possible specimens of peripheral blood, liver, stomach contents, vitreous humor, and muscle can be useful for toxicological analysis. In some countries, legislation or religious custom may mitigate against the removal of postmortem tissue unless shown to be necessary. The availability of a sensitive and broad ranging near-body screening test may provide a useful tool to assist pathologists in making decisions regarding the retention of tissues for toxicology analysis. We describe the performance of the Randox drugs-of-abuse (DOA) arrays, DOA I and DOA II, for near-body screening using whole blood, urine, vitreous humor, liver, and psoas major muscle. Samples were obtained from 106 autopsies and screened for the presence of amphetamine, barbiturates, benzodiazepines, benzoylecgonine, buprenorphine, cannabinoids, fentanyl, ketamine, lysergic acid diethylamide, methadone, methamphetamine, methaqualone, methylenedioxymethylamphetamine (Ecstasy), opiates, oxycodone, phencyclidine, and propoxyphene in the mortuary whilst the postmortem was being performed. Blood from each case underwent confirmatory analysis using either gas chromatography-mass spectrometry, liquid chromatography with tandem mass spectrometry or diode array detection. Excellent agreement between the near-body screening tests on a variety of tissues and confirmatory analyses in blood was obtained.

Modeling Approach To Characterize Intraocular Doripenem Pharmacokinetics after Intravenous Administration to Rabbits, with Tentative Extrapolation to Humans

The aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min (n = 5), 1 h (n = 5), 2 h (n = 5), and 3 h (n = 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans.

Evaluation of glycosylated hemoglobin and glycolsylated albumin levels in forensic autopsies

There may be difficulties in determining causes of sudden, unexpected deaths in medico-legal practice. It is known that sudden, unexpected deaths may result from diabetes mellitus and its complications. However, there is an ongoing debate on whether many parameters recommended to diagnose post-mortem diabetes mellitus are reliable. The aim of this study was to determine whether glycosylated haemoglobin (HbA1c) and glyscosylated albumin (fructosamine) measures could be used to diagnose post-mortem diabetes mellitus in forensic autopsies and to contribute to limited data on the issue reported in the literature. Method: We obtained blood and vitreous humor specimens from 146 decedents aged over 18 years and exposed to forensic autopsies. Results: The mean age of the cases was 46 ± 16.39 years (min 19yrs, max 85yrs) and 87.7% of the cases were male. HbA1c and fructosamine levels were higher than the standard values in 51 and 9 cases respectively. Of six cases with a history of diabetes mellitus, one had high fructosamine levels and five had high HbA1c levels. Fructosamine and HbA1c levels were high in three and 20 deaths from natural causes respectively and 12 of these deaths were caused by cardiovascular disorders. There was no significant relation between causes of deaths and HbA1c and fructosamine levels. Conclusion: The results of this study will contribute to the limited data on diabetes mellitus in sudden, unexpected deaths. It can be suggested that measurements of HbA1c and fructosamine levels should be included in routine autopsy protocols.

Measurement of ethyl glucuronide in vitreous humor with liquid chromatography–mass spectrometry

Background It is important to detect alcohol intake in postmortem investigations. However it can be difficult to interpret the results of alcohol analysis in putrefied corpses. To avoid this difficulty, there have been studies on detection of ethyl glucuronide (EtG), a non-oxidative metabolite of ethyl alcohol. The aim of this study was investigate EtG levels in vitreous humor (VH), a valuable material in postmortem investigations, and to compare VH EtG levels with blood and urine EtG levels. Methods Blood, urine and VH specimens were collected from 110 cases. Twenty-four cases in which ethyl alcohol was detected were included in the study. Although ethanol could not be detected, one case was added after having positive results of EtG levels in urine and VH as if he was claimed that he was an alcoholic and he had taken alcohol when he died but it could not be detected after 6 days of hospitalization. Liquid chromatography–mass spectrometry was used to investigate EtG in blood, urine and VH specimens from 25 cases. Results and conclusion VH EtG was in measurable amounts in 19 cases ( n: 25). In fact, VH EtG levels ranged from 0.05 to 1.90 mg/L and were below the limit of detection (LOD is 0.03 mg/L) in six cases ( n: 25). Blood EtG was in measurable amounts in 21 cases ( n: 25). Blood EtG levels ranged from 0.64 to 5.82 mg/L and were below the limit of detection (LOD is 0.083 mg/L) in four cases. EtG was detected in urine in 17 cases ( n: 19). Urine EtG levels ranged from 0.25 to 623 mg/L and were below the limit of detection (LOD is 0.12 mg/L) in one case. There was a significant relation between VH EtG levels and blood and urine EtG levels. The results of the study showed that postmortem VH EtG can be measured to reveal alcohol intake.

Application of the Cozart DDS system to postmortem screening of drugs of abuse in vitreous humor

The analysis of drugs of abuse in human specimens is essential in forensic medicine. This study evaluated the use of Cozart DDS for postmortem screening of some drugs of abuse in vitreous humor (VH) prior to forensic autopsies. The Cozart DDS is an on-site drug detection system that has been validated for oral fluid. Seventy-one VH specimens were obtained from cadavers. Causes of death included injury, drug poisoning, natural disorders, and traffic accidents. The samples were tested for cannabis, cocaine, opiate, amphetamine, and methamphetamine. Thirty-three of 71 samples were positive for drugs of abuse (42% for cocaine, 28% for cannabis, 26% for opiates, and 3% for methamphetamine). The positive specimens for opiates and methamphetamine were reexamined by gas chromatography-mass spectrometry (GC-MS); benzoylecgonine (cocaine product) was detected by liquid chromatography-tandem mass spectrometry (LC-MS-MS). All positive results for cocaine or its products and opiates by the Cozart test were confirmed by MS analysis, whereas one positive result for methamphetamine was negative by MS. The Cozart DDS system is generally a useful screening test for VH specimens prior to autopsies, because of its simplicity and rapidness.

Phencyclidine and cannabinoids in vitreous humor

Vitreous humor (VH) is routinely collected at autopsy for the testing of electrolytes and ethanol. In recent years drugs of abuse have been detected in this specimen. In this study the authors assayed 30 VH samples for phencyclidine (PCP) and 50 specimens for cannabinoids. Specimens were screened by immunoassay and then assayed for PCP by GC-FID and cannabinoids by GC/MS. Eighteen (60%) specimens screened positive for PCP using a cutoff of 25 ng/mL. Quantitative analysis showed PCP concentrations in VH that screened positive ranged 30–290 ng/mL. Corresponding blood concentrations were 50–600 ng/mL. VH PCP concentrations in the 12 cases which screened negative were 40–470 ng/mL. False negative results were probably due to matrix effects. All VH specimens screened for cannabinoids were negative. Ten negative screening specimens assayed by GC/MS yielded 1 11-nor-9-carboxy-delta-9-tetrahydrocannabinol positive result at 2 ng/mL. These data indicated that VH maybe a useful specimen for the detection of PCP but not for cannabinoids.

Distribution of Phencyclidine into Vitreous Humor

Vitreous humor is a fluid contained in the eye that is largely composed of water. The advantages of vitreous humor as a specimen for postmortem drug analysis include its relatively low susceptibility to contamination and the ability to analyze vitreous humor with little or no pretreatment. The postmortem analysis of ethanol in vitreous humor has been well established. However, studies of drug disposition into vitreous humor are limited. Heart blood, subclavian blood, and vitreous humor specimens from 26 phencyclidine-positive postmortem cases were analyzed to evaluate the distribution of phencyclidine into vitreous humor. Phencyclidine intoxication was not the cause of death in any of the cases analyzed. Specimens were analyzed by solid-phase extraction followed by gas chromatography-mass spectrometry. All positive blood specimens were associated with a positive vitreous humor specimen. On average, the blood phencyclidine concentrations were greater than the vitreous humor phencyclidine concentrations, with average blood/vitreous ratios of 2.85 for heart blood and 2.51 for subclavian blood. However, there was considerable variability between cases, which indicates that although vitreous humor is an appropriate specimen for the detection of phencyclidine in postmortem cases, its interpretative value is limited.

Distribution of 11-Nor-9-Carboxy-Δ9-tetrahydrocannabinol in Traffic Fatality Cases

11-nor-9-carboxy-Delta9-tetrahydrocannabinol (THC-COOH) distributions in postmortem specimens are rarely reported. Fifty New Jersey State Medical Examiner's cases in which automobile accident deaths suspected of involving marijuana intake were studied for the distributions of THC-COOH in postmortem urine, blood, vitreous humor, and bile specimens. Cases were selected based on immunoassay (TDx) urine test results. If the preliminary urine test indicated the presence of THC-COOH (apparent THC-COOH concentration > or = 20 ng/mL), urine, heart blood, vitreous humor, and bile specimens from the case were analyzed for THC-COOH concentrations by gas chromatography-mass spectrometry. The mean, standard deviation, and range of THC-COOH in heart blood, urine, and bile found in these 50 cases were 0.081, 0.082, and 0.016-0.33 microg/mL; 0.314, 0.415, and 0.044-2.33 microg/mL; and 12.9, 11.4, and 1.03-43.7 microg/mL, respectively. THC-COOH was absent (detection limit, 1 ng/mL) or at low concentration (< 10 ng/mL) in vitreous humor specimens. The mean, standard deviation, and range of the bile-to-blood and urine-to-blood ratios were 242, 196, and 17.2-888 and 4.70, 4.05, and 1.14-19.2, respectively. The highest concentrations of THC-COOH were found in bile and the lowest in vitreous humor. These findings are consistent with the high hydrophobicity nature of THC-COOH and further suggest that bile is the specimen of choice for detecting low level of THC-COOH in postmortem cases.