Fasting upregulates the monocarboxylate transporter MCT1 at the rat blood-brain barrier through PPAR δ activation

BACKGROUND

The blood-brain barrier (BBB) is pivotal for the maintenance of brain homeostasis and it strictly regulates the cerebral transport of a wide range of endogenous compounds and drugs. While fasting is increasingly recognized as a potential therapeutic intervention in neurology and psychiatry, its impact upon the BBB has not been studied. This study was designed to assess the global impact of fasting upon the repertoire of BBB transporters.

METHODS

We used a combination of in vivo and in vitro experiments to assess the response of the brain endothelium in male rats that were fed ad libitum or fasted for one to three days. Brain endothelial cells were acutely purified and transcriptionaly profiled using RNA-Seq. Isolated brain microvessels were used to assess the protein expression of selected BBB transporters through western blot. The molecular mechanisms involved in the adaptation to fasting were investigated in primary cultured rat brain endothelial cells. MCT1 activity was probed by in situ brain perfusion.

RESULTS

Fasting did not change the expression of the main drug efflux ATP-binding cassette transporters or P-glycoprotein activity at the BBB but modulated a restrictive set of solute carrier transporters. These included the ketone bodies transporter MCT1, which is pivotal for the brain adaptation to fasting. Our findings in vivo suggested that PPAR δ, a major lipid sensor, was selectively activated in brain endothelial cells in response to fasting. This was confirmed in vitro where pharmacological agonists and free fatty acids selectively activated PPAR δ, resulting in the upregulation of MCT1 expression. Moreover, dosing rats with a specific PPAR δ antagonist blocked the upregulation of MCT1 expression and activity induced by fasting.

CONCLUSIONS

Altogether, our study shows that fasting affects a selected set of BBB transporters which does not include the main drug efflux transporters. Moreover, we describe a previously unknown selective adaptive response of the brain vasculature to fasting which involves PPAR δ and is responsible for the up-regulation of MCT1 expression and activity. Our study opens new perspectives for the metabolic manipulation of the BBB in the healthy or diseased brain.

Urinary Free Cortisol Determination and Interferences Studies Using Liquid Chromatography Coupled to Tandem Mass Spectrometry after On-Line Solid Phase Extraction Based on TurboflowTM Chromatography

(1) A 24 h urinary free cortisol (UFF) is one of the first-line exams recommended for the diagnosis of Cushing's syndrome. In a hospital hormonology department, this activity can exceed several hundred dosages per week. The UFF is generally determined via an immunoassay with an automate using a chemiluminescence or electrochemiluminescence detection system. To increase the cortisol concentration in the analyzed sample, the automated analysis is preceded by urine extraction, which does not prevent there from being some interferences due to other steroids with close structures. (2) This paper describes the development of on-line solid phase extraction coupled to liquid chromatography and mass spectrometry for the analysis of urinary free cortisol. The on-line extraction was based on the TurboflowTM chromatography coupled to the analytical column by two valves, easily available for the laboratories. (3) The choice of the Accucore Polar Premium® analytical column made it possible to avoid analytical interferences with exogenous or endogenous molecules having the same SRM transition (363 → 121) as cortisol. (4) The method was fully validated in the range of clinically relevant concentrations from the lower limit of quantification (LLOQ) to 411.75 nmol·L-1.

Functional and targeted proteomics characterization of a human primary endothelial cell model of the blood-brain barrier (BBB) for drug permeability studies

The blood-brain barrier (BBB) protects the brain from toxins but hinders the penetration of neurotherapeutic drugs. Therefore, the blood-to-brain permeability of chemotherapeutics must be carefully evaluated. Here, we aimed to establish a workflow to generate primary cultures of human brain microvascular endothelial cells (BMVECs) to study drug brain permeability and bioavailability. Furthermore, we characterized and validated this BBB model in terms of quantitative expression of junction and drug-transport proteins, and drug permeability. We isolated brain microvessels (MVs) and cultured BMVECs from glioma patient biopsies. Then, we employed targeted LC-MS proteomics for absolute protein quantification and immunostaining to characterize protein localization and radiolabeled drugs to predict drug behavior at the Human BBB. The abundance levels of ABC transporters, junction proteins, and cell markers in the cultured BMVECs were similar to the MVs and correctly localized to the cell membrane. Permeability values (entrance and exit) and efflux ratios tested in vitro using the primary BMVECs were within the expected in vivo values. They correctly reflected the transport mechanism for 20 drugs (carbamazepine, diazepam, imipramine, ketoprofen, paracetamol, propranolol, sulfasalazine, terbutaline, warfarin, cimetidine, ciprofloxacin, digoxin, indinavir, methotrexate, ofloxacin, azidothymidine (AZT), indomethacin, verapamil, quinidine, and prazosin). We established a human primary in vitro model suitable for studying blood-to-brain drug permeability with a characterized quantitative abundance of transport and junction proteins, and drug permeability profiles, mimicking the human BBB. Our results indicate that this approach could be employed to generate patient-specific BMVEC cultures to evaluate BBB drug permeability and develop personalized therapeutic strategies.

Decreased steroidogenic enzyme activity in benign adrenocortical tumors is more pronounced in bilateral lesions as determined by steroid profiling in LC-MS/MS during ACTH stimulation test

OBJECTIVE

Large response of steroid precursors, including 17-hydroxyprogesterone, to adrenocorticotropic hormone (ACTH) has been described in adrenocortical tumors, suggesting the existence of intra-tumoral enzymatic deficiencies. This study aimed to compare steroidogenesis enzymes activity in unilateral and bilateral benign tumors using serum steroid profiling in liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in the basal state and after ACTH 1-24 stimulation.

DESIGN AND METHODS

A serum profile of seven consecutive adrenal steroids was determined in LC-MS/MS in the basal state (T0) and after ACTH 1-24 stimulation (T60) in 35 patients with bilateral adrenocortical tumors (BL), 38 patients with unilateral tumors (UL) and 37 control subjects (CT). Response amplitude of each individual steroid was evaluated by T60/T0 ratio, whereas enzymatic activity was assessed by the downstream/upstream steroid ratio. Adrenal volume was quantified by a semi-automatic segmentation method.

RESULTS

For the seven steroids assayed, the amplitude of response to ACTH was higher in BL than in UL and in CT. The difference between BL and UL persisted even after matching patients on adrenal volume. On glucocorticoids pathway, enzymatic activity of CYP11B1 was significantly decreased in BL (78.3 (43.1-199.4)) in comparison to both UL (122.7 (13.8-228.4), P = 0.0002) and CT (186.8 (42.1-1236.3), P < 0.0001). On mineralocorticoids and androgens pathways, the enzymatic activity of CYP11B2 and CYP17A1-17,20 lyase was also lower in BL than UL and CT.

CONCLUSIONS

Decreased activity of distal steroidogenesis enzymes CYP11B1, CYP11B2 and CYP17A1-17,20 lyase, responsible for an explosive response to ACTH of upstream precursors in bilateral tumors, limits the synthesis of bioactive steroids, in particular cortisol, despite the increase in adrenal mass.

SIGNIFICANCE STATEMENT

Activity of distal steroidogenesis enzymes (CYP11B1, CYP11B2 and CYP17A1 on glucocorticoids, mineralocorticoids and androgens pathways, respectively) is decreased in adrenocortical benign tumors. This decrease is more pronounced in bilateral lesions and seems to depend more on the nature of the lesion than on the increase in adrenal volume. It is responsible for the explosive response to ACTH of steroid precursors located upstream of these enzymes. It probably allows bioactive steroids, particularly cortisol, to stay in the normal range for a long time despite the increase in adrenal mass.

Exposure of human cerebral microvascular endothelial cells hCMEC/D3 to laminar shear stress induces vascular protective responses

Endothelial cells (ECs) are constantly submitted in vivo to hemodynamical forces derived from the blood circulation, including shear stress (SS). ECs are able to detect SS and consequently adapt their phenotype, thus affecting many endothelial functions. If a plethora of shear stress-regulated molecular networks have been described in peripheral ECs, less is known about the molecular responses of microvascular brain ECs which constitute the blood-brain barrier (BBB). In this work, we investigated the response of human cerebral microvascular ECs to laminar physiological shear stress using the well characterized hCMEC/D3 cell line. Interestingly, we showed that hCMEC/D3 cells responded to shear stress by aligning perpendicularly to the flow direction, contrary to peripheral endothelial cells which aligned in the flow direction. Whole proteomic profiles were compared between hCMEC/D3 cells cultured either in static condition or under 5 or 10 dyn.cm-2 SS for 3 days. 3592 proteins were identified and expression levels were significantly affected for 3% of them upon both SS conditions. Pathway analyses were performed which revealed that most proteins overexpressed by SS refer to the antioxidant defense, probably mediated by activation of the NRF2 transcriptional factor. Regarding down-regulated proteins, most of them participate to the pro-inflammatory response, cell motility and proliferation. These findings confirm the induction of EC quiescence by laminar physiological SS and reveal a strong protective effect of SS on hCMEC/D3 cells, suggesting a similar effect on the BBB. Our results also showed that SS did not significantly increase expression levels nor did it affect the localization of junctional proteins and did not afect either the functional activity of several ABC transporters (P-glycoprotein and MRPs). This work provides new insights on the response of microvascular brain ECs to SS and on the importance of SS for optimizing in vitro BBB models.

An Interspecies Molecular and Functional Study of Organic Cation Transporters at the Blood-Brain Barrier: From Rodents to Humans

Organic cation transporters (OCTs) participate in the handling of compounds in kidneys and at the synaptic cleft. Their role at the blood-brain barrier (BBB) in brain drug delivery is still unclear. The presence of OCT1,2,3 (SLC22A1-3) in mouse, rat and human isolated brain microvessels was investigated by either qRT-PCR, quantitative proteomics and/or functional studies. BBB transport of the prototypical substrate [³H]-1-methyl-4-phenylpyridinium ([³H]-MPP⁺) was measured by in situ brain perfusion in six mouse strains and in Sprague Dawley rats, in primary human brain microvascular endothelial cells seeded on inserts, in the presence or absence of OCTs and a MATE1 (SLC49A1) inhibitor. The results show negligible OCT1 (SLC22A1) and OCT2 (SLC22A2) expression in either mice, rat or human brain microvessels, while OCT3 expression was identified in rat microvessels by qRT-PCR. The in vitro human cellular uptake of [³H]-MPP⁺ was not modified by OCTs/MATE-inhibitor. Brain transport of [³H]-MPP⁺ remains unchanged between 2- and 6-month old mice, and no alteration was observed in mice and rats with inhibitors. In conclusion, the evidenced lack of expression and/or functional OCTs and MATE at the BBB allows the maintenance of the brain homeostasis and function as it prevents an easy access of their neurotoxicant substrates to the brain parenchyma.

ABC Transporters at the Blood-Brain Interfaces, Their Study Models, and Drug Delivery Implications in Gliomas

Drug delivery into the brain is regulated by the blood-brain interfaces. The blood-brain barrier (BBB), the blood-cerebrospinal fluid barrier (BCSFB), and the blood-arachnoid barrier (BAB) regulate the exchange of substances between the blood and brain parenchyma. These selective barriers present a high impermeability to most substances, with the selective transport of nutrients and transporters preventing the entry and accumulation of possibly toxic molecules, comprising many therapeutic drugs. Transporters of the ATP-binding cassette (ABC) superfamily have an important role in drug delivery, because they extrude a broad molecular diversity of xenobiotics, including several anticancer drugs, preventing their entry into the brain. Gliomas are the most common primary tumors diagnosed in adults, which are often characterized by a poor prognosis, notably in the case of high-grade gliomas. Therapeutic treatments frequently fail due to the difficulty of delivering drugs through the brain barriers, adding to diverse mechanisms developed by the cancer, including the overexpression or expression de novo of ABC transporters in tumoral cells and/or in the endothelial cells forming the blood-brain tumor barrier (BBTB). Many models have been developed to study the phenotype, molecular characteristics, and function of the blood-brain interfaces as well as to evaluate drug permeability into the brain. These include in vitro, in vivo, and in silico models, which together can help us to better understand their implication in drug resistance and to develop new therapeutics or delivery strategies to improve the treatment of pathologies of the central nervous system (CNS). In this review, we present the principal characteristics of the blood-brain interfaces; then, we focus on the ABC transporters present on them and their implication in drug delivery; next, we present some of the most important models used for the study of drug transport; finally, we summarize the implication of ABC transporters in glioma and the BBTB in drug resistance and the strategies to improve the delivery of CNS anticancer drugs.

Assessment of brain delivery of a model ABCB1/ABCG2 substrate in patients with non-contrast-enhancing brain tumors with positron emission tomography

BACKGROUND

P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) are two efflux transporters expressed at the blood-brain barrier which effectively restrict the brain distribution of the majority of currently known anticancer drugs. High-grade brain tumors often possess a disrupted blood-brain tumor barrier (BBTB) leading to enhanced accumulation of magnetic resonance imaging contrast agents, and possibly anticancer drugs, as compared to normal brain. In contrast to high-grade brain tumors, considerably less information is available with respect to BBTB integrity in lower grade brain tumors.

MATERIALS AND METHODS

We performed positron emission tomography imaging with the radiolabeled ABCB1 inhibitor [¹¹C]tariquidar, a prototypical ABCB1/ABCG2 substrate, in seven patients with non-contrast -enhancing brain tumors (WHO grades I-III). In addition, ABCB1 and ABCG2 levels were determined in surgically resected tumor tissue of four patients using quantitative targeted absolute proteomics.

RESULTS

Brain distribution of [¹¹C]tariquidar was found to be very low across the whole brain and not significantly different between tumor and tumor-free brain tissue. Only one patient showed a small area of enhanced [¹¹C]tariquidar uptake within the brain tumor. ABCG2/ABCB1 ratios in surgically resected tumor tissue (1.4 ± 0.2) were comparable to previously reported ABCG2/ABCB1 ratios in isolated human micro-vessels (1.3), which suggested that no overexpression of ABCB1 or ABCG2 occurred in the investigated tumors.

CONCLUSIONS

Our data suggest that the investigated brain tumors had an intact BBTB, which is impermeable to anticancer drugs, which are dual ABCB1/ABCG2 substrates. Therefore, effective drugs for antitumor treatment should have high passive permeability and lack ABCB1/ABCG2 substrate affinity.

TRIAL REGISTRATION

European Union Drug Regulating Authorities Clinical Trials Database (EUDRACT), 2011-004189-13. Registered on 23 February 2012, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2011-004189-13.

Cannabidiol Increases Proliferation, Migration, Tubulogenesis, and Integrity of Human Brain Endothelial Cells through TRPV2 Activation

The effect of cannabidiol (CBD), a high-affinity agonist of the transient receptor potential vanilloid-2 (TRPV2) channel, has been poorly investigated in human brain microvessel endothelial cells (BMEC) forming the blood-brain barrier (BBB). TRPV2 expression and its role on Ca²⁺ cellular dynamics, trans-endothelial electrical resistance (TEER), cell viability and growth, migration, and tubulogenesis were evaluated in human primary cultures of BMEC (hPBMEC) or in the human cerebral microvessel endothelial hCMEC/D3 cell line. Abundant TRPV2 expression was measured in hCMEC/D3 and hPBMEC by qRT-PCR, Western blotting, nontargeted proteomics, and cellular immunofluorescence studies. Intracellular Ca²⁺ levels were increased by heat and CBD and blocked by the nonspecific TRP antagonist ruthenium red (RR) and the selective TRPV2 inhibitor tranilast (TNL) or by silencing cells with TRPV2 siRNA. CBD dose-dependently induced the hCMEC/D3 cell number (EC₅₀ 0.3 ± 0.1 μM), and this effect was fully abolished by TNL or TRPV2 siRNA. A wound healing assay showed that CBD induced cell migration, which was also inhibited by TNL or TRPV2 siRNA. Tubulogenesis of hCMEC/D3 cells in 3D matrigel cultures was significantly increased by 41 and 73% after a 7 or 24 h CBD treatment, respectively, and abolished by TNL. CBD also increased the TEER of hPBMEC monolayers cultured in transwell, and this was blocked by TNL. Our results show that CBD, at extracellular concentrations close to those observed in plasma of patients treated by CBD, induces proliferation, migration, tubulogenesis, and TEER increase in human brain endothelial cells, suggesting CBD might be a potent target for modulating the human BBB.

Humanization of the Blood-Brain Barrier Transporter ABCB1 in Mice Disrupts Genomic Locus - Lessons from Three Unsuccessful Approaches

ATP-binding cassette (ABC) transporters are of major importance for the restricted access of toxins and drugs to the human body. At the body's barrier tissues like the blood-brain barrier, these transporters are highly represented. Especially, ABCB1 (P-glycoprotein) has been a priority target of pharmaceutical research, for instance, to aid chemotherapy of cancers, therapy resistant epilepsy, and lately even neurodegenerative diseases. To improve translational research, the humanization of mouse genes has become a popular tool although, like recently seen for Abcb1, not all approaches were successful. Here, we report the characterization of another unsuccessful commercially available ABCB1 humanized mouse strain. In vivo assessment of transporter activity using positron emission tomography imaging revealed a severe reduction of ABCB1 function in the brain of these mice. Analyses of brain mRNA and protein expression showed that the murine Abcb1a gene is still expressed in homozygous humanized animals while expression of the human gene is minimal. Promoter region analyses underpinned that the introduced human gene might dysregulate normal expression and provided insights into the regulation of both transcription and translation of Abcb1a. We conclude that insertion of the human coding DNA sequence (CDS) into exon 3 instead of exon 2 most probably represents a more promising strategy for Abcb1a humanization.

rFSH in medically assisted procreation: Evidence for ovarian follicular hyperplasia and interest of mass spectrometry to measure 17-hydroxyprogesterone and Δ4-androstenedione in serum

Ovarian monitoring requires the determination of serum estradiol and progesterone levels. We investigated whole follicular steroidogenesis under rFSH in medically assisted procreation (MAP: 26 IVF, 24 ICSI) compared to 11 controls (IUI). Estrone, estradiol, Δ4-androstenedione, testosterone, progesterone and 17-hydroxyprogesterone were measured by immunoassay and mass spectrometry except for estrogens. At the start of a spontaneous or induced cycle, steroids levels fluctuated within normal ranges: estradiol (314-585 pmol/L), estrone (165-379 pmol/L) testosterone (1.3-1.6 nmol/L), Δ4-androstenedione (4.5-5.6 nmol/L), 17-hydroxyprogesterone (2.1-2.2 nmol/L) and progesterone (1.8-1.9 nmol/L). 17-hydroxyprogesterone, Δ 4-androstenedione and estradiol predominated. Then estradiol and oestrone levels rise, but less markedly for oestrone in IUI. In MAP, rFSH injections induce a sharp increase in estrogens associated with a rise in 17-hydroxyprogesterone and Δ4-androstenedione levels, disrupting oestrogen/androgen ratios. rFSH stimulation induces an ovarian hyperplasia and Δ4pathway which could become abnormal. Determining 17-hydroxyprogesterone and Δ4-androstenedione levels with LC-MS/MS may therefore be useful in managing recurrent MAP failures.

Distribution of trans-resveratrol and its metabolites after acute or sustained administration in mouse heart, brain, and liver

SCOPE

Trans-resveratrol is widely studied for its potentially beneficial effects on numerous disorders. It is rapidly metabolized and its metabolites can exhibit biological activity. The present study aimed to investigate whether acute or sustained trans-resveratrol administration impacted on the distribution of trans-resveratrol and its metabolites in brain, heart, and liver.

METHODS AND RESULTS

We used ultra-HPLC quadrupole-TOF (UHPLC-Q-TOF) in a full-scan mode to identify and assess large numbers of resveratrol metabolites. For acute intake, mice were overfed with a single dose of trans-resveratrol (150 mg/kg) and organs were collected after 30 and 60 min. For sustained intake, trans-resveratrol was given in the chow (0.04% w/w corresponding to 40 mg/kg/day), and plasma and the organs were collected after 3 months of this resveratrol diet. We found that trans-resveratrol-3-O-glucuronide and resveratrol-3-sulfate were the main metabolites found after acute intake, and free trans-resveratrol (in the brain and heart) and dihydroresveratrol derivatives were found after sustained administration CONCLUSIONS: Our results show notable differences between acute and sustained administration of trans-resveratrol and distribution of trans-resveratrol and its metabolites in mouse heart, brain, and liver. The results suggest a strategy for development of galenic forms of resveratrol.

Generation and Characterization of a Breast Cancer Resistance Protein Humanized Mouse Model

Breast cancer resistance protein (BCRP) is expressed in various tissues, such as the gut, liver, kidney and blood brain barrier (BBB), where it mediates the unidirectional transport of substrates to the apical/luminal side of polarized cells. Thereby BCRP acts as an efflux pump, mediating the elimination or restricting the entry of endogenous compounds or xenobiotics into tissues and it plays important roles in drug disposition, efficacy and safety. Bcrp knockout mice (Bcrp(-/-)) have been used widely to study the role of this transporter in limiting intestinal absorption and brain penetration of substrate compounds. Here we describe the first generation and characterization of a mouse line humanized for BCRP (hBCRP), in which the mouse coding sequence from the start to stop codon was replaced with the corresponding human genomic region, such that the human transporter is expressed under control of the murineBcrppromoter. We demonstrate robust human and loss of mouse BCRP/Bcrp mRNA and protein expression in the hBCRP mice and the absence of major compensatory changes in the expression of other genes involved in drug metabolism and disposition. Pharmacokinetic and brain distribution studies with several BCRP probe substrates confirmed the functional activity of the human transporter in these mice. Furthermore, we provide practical examples for the use of hBCRP mice to study drug-drug interactions (DDIs). The hBCRP mouse is a promising model to study the in vivo role of human BCRP in limiting absorption and BBB penetration of substrate compounds and to investigate clinically relevant DDIs involving BCRP.

Effect of Subchronic Intravenous Morphine Infusion and Naloxone-Precipitated Morphine Withdrawal on P-gp and Bcrp at the Rat Blood-Brain Barrier

Chronic morphine regimen increases P-glycoprotein (P-gp) and breast cancer-resistance protein (Bcrp) expressions at the rat blood–brain barrier (BBB) but what drives this effect is poorly understood. The objective of this study is to assess subchronic continuous morphine infusion and naloxone-precipitated morphine withdrawal effects on P-gp/Bcrp contents and activities at the rat BBB. Rats were treated either with (i) a continuous i.v. morphine for 120 h, (ii) escalating morphine dosing (10-40 mg/kg, i.p., 5 days), (iii) a chronic morphine regimen (10 mg/kg s.c., 5 days) followed by a withdrawal period (2 days) and treatment for 3 additional days. Animal behavior was assessed after naloxone-precipitated withdrawal (1 mg/kg, s.c.). P-gp/Bcrp expressions and activities were determined in brain microvessels by qRT-PCR, Western blot, UHPLC–MS/MS, and in situ brain perfusion of P-gp or Bcrp substrates. Results show continuous i.v. morphine did not change P-gp/Bcrp protein levels in rat brain microvessels, whereas naloxone-precipitated withdrawal after escalating or chronic morphine dose regimen increased Mdr1a and Bcrp mRNA levels by 1.4-fold and 2.4-fold, respectively. Conversely, P-gp/Bcrp protein expressions remained unchanged after naloxone administration, and brain uptake of [3H]-verapamil (P-gp) and [3H]-mitoxantrone (Bcrp) was not altered. The study concludes subchronic morphine infusion and naloxone-precipitated morphine withdrawal have poor effect on P-gp/Bcrp levels at the rat BBB.

Resveratrol Improved Flow-Mediated Outward Arterial Remodeling in Ovariectomized Rats with Hypertrophic Effect at High Dose

Objectives

Chronic increases in blood flow in resistance arteries induce outward remodeling associated with increased wall thickness and endothelium-mediated dilatation. This remodeling is essential for collateral arteries growth following occlusion of a large artery. As estrogens have a major role in this remodeling, we hypothesized that resveratrol, described as possessing phytoestrogen properties, could improve remodeling in ovariectomized rats.

Methods

Blood flow was increased in vivo in mesenteric arteries after ligation of adjacent arteries in 3-month old ovariectomized rats treated with resveratrol (5 or 37.5 mg/kg per day: RESV5 or RESV37.5) or vehicle. After 2 weeks arterial structure and function were measured in vitro in high flow (HF) and normal flow (NF) arteries isolated from each rat.

Results

Arterial diameter was greater in HF than in NF arteries in ovariectomized rats treated with RESV5 or RESV37.5, not in vehicle-treated rats. In mice lacking estrogen receptor alpha diameter was equivalent in HF and NF arteries whereas in mice treated with RESV5 diameter was greater in HF than in NF vessels. A compensatory increase in wall thickness and a greater phenylephrine-mediated contraction were observed in HF arteries. This was more pronounced in HF arteries from RESV37.5-treated rats. ERK1/2 phosphorylation, involved in hypertrophy and contraction, were higher in RESV37.5-treated rats than in RESV5- and vehicle-treated rats. Endothelium-dependent relaxation was greater in HF than in NF arteries in RESV5-treated rats only. In HF arteries from RESV37.5-treated rats relaxation was increased by superoxide reduction and markers of oxidative stress (p67phox, GP91phox) were higher than in the 2 other groups.

Conclusion

Resveratrol improved flow-mediated outward remodeling in ovariectomized rats thus providing a potential therapeutic tool in menopause-associated ischemic disorders. This effect seems independent of the estrogen receptor alpha. Nevertheless, caution should be taken with high doses inducing excessive contractility and hypertrophy in association with oxidative stress in HF arteries.

Incidence of the melting-degradation process of vitamin C on the determination of the phase diagram with acetaminophen enhanced by high performance liquid chromatography tools

The exact solid–liquid equilibrium between ascorbic acid and acetaminophen was established combining high performance liquid chromatography and differential scanning calorimetry.

Resveratrol metabolism in a non-human primate, the grey mouse lemur (Microcebus murinus), using ultra-high-performance liquid chromatography-quadrupole time of flight

The grey mouse lemur (Microcebus murinus) is a non-human primate used to study the ageing process. Resveratrol is a polyphenol that may increase lifespan by delaying age-associated pathologies. However, no information about resveratrol absorption and metabolism is available for this primate. Resveratrol and its metabolites were qualitatively and quantitatively analyzed in male mouse-lemur plasma (after 200 mg.kg⁻¹ of oral resveratrol) by ultra-high performance liquid chromatography (UHPLC), coupled to a quadrupole-time-of-flight (Q-TOF) mass spectrometer used in full-scan mode. Data analyses showed, in MS^E mode, an ion common to resveratrol and all its metabolites: m/z 227.072, and an ion common to dihydro-resveratrol metabolites: m/z 229.08. A semi-targeted study enabled us to identify six hydrophilic resveratrol metabolites (one diglucurono-conjugated, two monoglucurono-conjugated, one monosulfo-conjugated and two both sulfo- and glucurono-conjugated derivatives) and three hydrophilic metabolites of dihydro-resveratrol (one monoglucurono-conjugated, one monosulfo-conjugated, and one both sulfo- and glucurono-conjugated derivatives). The presence of such metabolites has been already detected in the mouse, rat, pig, and humans. Free resveratrol was measurable for several hours in mouse-lemur plasma, and its two main metabolites were trans-resveratrol-3-O-glucuronide and trans-resveratrol-3-sulfate. Free dihydro-resveratrol was not measurable whatever the time of plasma collection, while its hydrophilic metabolites were present at 24 h after intake. These data will help us interpret the effect of resveratrol in mouse lemurs and provide further information on the inter-species characteristics of resveratrol metabolism.

Ultra high performance liquid chromatography-quadrupole-time of flight analysis for the identification and the determination of resveratrol and its metabolites in mouse plasma

Resveratrol is a polyphenol that has numerous interesting biological properties, but, per os, it is quickly metabolized. Some of its metabolites are more concentrated than resveratrol, may have greater biological activities, and may act as a kind of store for resveratrol. Thus, to understand the biological impact of resveratrol on a physiological system, it is crucial to simultaneously analyze resveratrol and its metabolites in plasma. This study presents an analytical method based on UHPLC-Q-TOF mass spectrometry for the quantification of resveratrol and of its most common hydrophilic metabolites. The use of (13)C- and D-labeled standards specific to each molecule led to a linear calibration curve on a larger concentration range than described previously. The use of high resolution mass spectrometry in the full scan mode enabled simultaneous identification and quantification of some hydrophilic metabolites not previously described in mice. In addition, UHPLC separation, allowing run times lower than 10 min, can be used in studies that requiring analysis of many samples.

Population pharmacokinetics of 3,4-methylenedioxymethamphetamine and main metabolites in rats

The pharmacokinetics of the recreational drug 3,4-methylenedioxymethamphetamine (MDMA) and its mains metabolites have never been modeled together. We therefore designed a model with which to analyze the pharmacokinetics of MDMA, 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) and to test the effect of covariates like gender and body weight on the pharmacokinetics. Rats (18 males and 18 females) were given 1 mg/kg MDMA iv, and the concentrations of MDMA, MDA, and HMMA were measured by high-performance liquid chromatography-mass spectrometry. Another 30 rats (15 males) were given 1 mg/kg MDA, and MDA and HMA were measured. A population pharmacokinetic model was developed to describe the changes in MDMA, HMMA, MDA, and HMA concentrations over time and to estimate interanimal variability. The influence of gender was tested using a likelihood ratio test. Estimated exposures of males and females to MDMA and its metabolites were compared using the Wilcoxon nonparametric test. An integrated six-compartment model adequately described the data. MDMA (two compartments) was transformed irreversible to HMMA (one compartment) and MDA (two compartments), which then produced HMA (one compartment). All rate constants were first order. Females given MDMA had significantly smaller MDMA distribution volumes than males, and they converted less MDMA to MDA than did males. Our MDMA, MDA, HMA, and HMMA model is suitable for examining the relationship between drug concentrations and its pharmacological/toxicological effects. Male rats were exposed to significantly more MDA and HMA than were females, which could explain why males are more sensitive to MDMA toxic effects than females.

Sprague-Dawley rats display sex-linked differences in the pharmacokinetics of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA)

The use of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has increased in recent years; it can lead to life-threatening hyperthermia and serotonin syndrome. Human and rodent males appear to be more sensitive to acute toxicity than are females. MDMA is metabolized to five main metabolites by the enzymes CYP1A2, CYP2D and COMT. Little is presently known about sex-dependent differences in the pharmacokinetics of MDMA and its metabolites. We therefore analyzed MDMA disposition in male and female rats by measuring the plasma and urine concentrations of MDMA and its metabolites using a validated LC-MS method. MDA AUC(last) and C(max) were 1.6- to 1.7-fold higher in males than in females given MDMA (5 mg/kg sc), while HMMA C(max) and AUC(last) were 3.2- and 3.5-fold higher, respectively. MDMA renal clearance was 1.26-fold higher in males, and that of MDA was 2.2-fold higher. MDMA AUC(last) and t(1/2) were 50% higher in females given MDMA (1 mg/kg iv). MDA C(max) and AUC(last) were 75-82% higher in males, with a 2.8-fold higher metabolic index. Finally, the AUC(last) of MDA was 0.73-fold lower in males given 1 mg/kg iv MDA. The volumes of distribution of MDMA and MDA at steady-state were similar in the two sexes. These data strongly suggest that differences in the N-demethylation of MDMA to MDA are major influences on the MDMA and MDA pharmacokinetics in male and female rats. Hence, males are exposed to significantly more toxic MDA, which could explain previously reported sexual dysmorphism in the acute effects and toxicity of MDMA in rats.

Identification of New Flavone-8-Acetic Acid Metabolites Using Mouse Microsomes and Comparison with Human Microsomes

Flavone-8-acetic acid (FAA) is a potent anticancer agent in mouse but has not shown activity in humans. Because FAA metabolism could play a role in this interspecies difference, our aim was to identify the metabolites formed in vitro using mouse microsomes compared with those in human microsomes. Mouse microsomes produced six metabolites as detected by reversed-phase high-performance liquid chromatography-mass spectrometry (MS). Three metabolites were identified as the 3'-, 4'-, or 6-hydroxy-FAA, by comparison with retention times and UV and MS spectra of standards. Two metabolites presented a molecular weight of 296 (FAA = 280) indicating the presence of one oxygen but did not correspond to any monohydroxylated FAA derivative. These two metabolites were identified as epoxides because they were sensitive to epoxide hydrolase. The position of the oxygen was determined by the formation of the corresponding phenols under soft acidic conditions: one epoxide yielded the 3'- and 4'-hydroxy-FAA, thus corresponding to the 3',4'-epoxy-FAA, whereas the other epoxide yielded 5- and 6-hydroxy-FAA, thus identifying the 5,6-epoxy-FAA. The last metabolite was assigned to the 3',4'-dihydrodiol-FAA because of its molecular weight (314) and sulfuric acid dehydration that indicated that the 3'- and 4'-positions were involved. Compared with mouse microsomes, human microsomes (2 pools and 15 individual microsomes) were unable to metabolize FAA to a significant extent. In conclusion, we have identified six new FAA metabolites formed by mouse microsomes, whereas human microsomes could not metabolize this flavonoid to a significant extent. The biological importance of the new metabolites identified herein remains to be evaluated.

Characterization of monohydroxylated derivatives of the anticancer agent flavone-8-acetic acid by liquid chromatography with on-line UV and mass spectrometry

The experimental anticancer agent flavone-8-acetic acid (FAA) is metabolized into several monohydroxylated derivatives using mouse microsomes. Because these metabolites could be involved in the biological effects of FAA, the aim of this study was to characterize all its possible monohydroxylated derivatives. To do so, we have developed a methodology using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with ultraviolet (UV) detection and mass spectrometry (MS) to analyze and identify FAA derivatives hydroxylated at the 2', 3', 4', 3, 5, 6, or 7 position. In RP-HPLC, 4'-, 3'-, 2'-, 6-, and 7-OH-FAA eluted before FAA, whereas 3- and 5-OH-FAA eluted after FAA. UV spectra showed a bathochromic shift of band I for all derivatives and of band II for 5- and 6-OH-FAA. In addition, the position of the OH group could be determined by the presence of certain product ions in MS. Ions at m/z 133 and 151 were specific for 2'-, 3'-, 4'-, and 3-OH-FAA, whereas the ion at m/z 177 was specific for 3-OH-FAA only. The ions m/z 133, 151 and 167 were specific for 2'-OH-FAA. Ions at m/z 149 were specific for the presence of the OH group on cycle A only (i.e., 5-, 6- or 7-OH-FAA). The presence of both product ions m/z 149 and 179 were specific for 7-OH-FAA. Finally, ions at m/z 149 and several product ions of even m/z values were specific for 5-OH-FAA. In conclusion, the methodology described can be used to identify all possible monohydroxylated FAA derivatives.

Analysis of theaflavins and thearubigins from black tea extract by MALDI-TOF mass spectrometry

Black tea contains two major groups of pigments, theaflavins (TFs) and thearubigins (TRs). TFs contain a bis-flavan substituted 1,2-dihydroxy-3,4-benzotropolone moiety. Unlike the TFs, TRs have not yet been characterized. The chemical structure of the TRs remains a mystery. The present paper reports our effort to study the structure of TFs and TRs using delayed pulsed ion extraction of ions generated via the matrix-assisted laser desorption ionization (MALDI) technique, on line with a Linear time-of-flight (TOF) mass spectrometer. Spectra of standard TFs show not only pseudomolecular ions but also ions resulting from fragmentation. The analysis of MALDI-TOF spectra of black tea fractions shows the structure of some TRs, which are similar to those of TFs because the same loss of mass is observed.

[Methods of use and behavior of cocaine addicts consulting medical-legal emergency units in Paris. Clinical aspects and urinary toxicology profile]

OBJECTIVE

Establish the epidemiological characteristics and urinary toxicological profiles of a population of cocaine addicts under police custody.

METHOD

A series of 60 cocaine addicts consulting the medico-legal emergency unit of the Hôtel-Dieu hospital in Paris was studied prospectively on the following elements: clinical characteristics, method of cocaine administration and association with other licit or illicit substances. Urinary toxicological analysis, using immuno-chemistry and chromatography linked to a mass spectrometer was systematically proposed to each patient.

RESULTS

Half of the 17 to 26 year-old patients declared having consumed cocaine for the past 2 to 5 years. Inhalation of the vapours and the intravenous route were used more than the cigarette or nasal route. The majority of 26 to 35 year-olds were multi-drug addicted, generally associating cocaine, heroine and tobacco. Analysis of the urine provided an objective assessment of the cocaine consumption of these persons under police custody in Paris.

CONCLUSION

Screening for urinary toxicity gives better knowledge on the consumption of addictive products by the person in whom urine was sampled. This study was conducted in cocaine addicts under police custody, and for the majority were social misfits. In this population, the consumption of crack by inhalation predominated.

Residual glutaraldehyde levels in fiberoptic endoscopes: measurement and implications for patient toxicity

Most gastroenterology societies recommend glutaraldehyde for fiberoptic endoscope disinfection. However, glutaraldehyde toxicity has been suspected in patients examined with endoscopes disinfected with this compound. The aim of our study was to determine the residual levels of glutaraldehyde in fiberoptic endoscopes after either manual or automatic disinfection and to evaluate the extent of toxicity. Furthermore, the procedures for disinfection currently performed by the department were compared with the new French guidelines. We used both manual and automatic disinfection procedures and flushed sterile distilled water through the lumens of endoscopes before use. Residual glutaraldehyde levels were determined using liquid chromatography coupled to spectrophotometric detection. In a total of 92 measurements it was found that residual glutaraldehyde levels were higher and more variable after manual disinfection (< 0.2-159.5 mg/L) than after automatic disinfection (< 0.2-6.3 mg/L). We conclude that local procedures for disinfection need to be improved to conform to the new French guidelines. Since thresholds for the toxic dose of glutaraldehyde and international norms for levels of residual glutaraldehyde in equipment have not been defined, additional studies combining accurate measurements in fiberoptic endoscopes and clinical observations of endoscopy patients will be required to draw more definitive conclusions.

Fast specific separation and sensitive quantification of bactericidal and sporicidal aldehydes by high-performance liquid chromatography: example of glutaraldehyde determination

This article describes the design and the validation of the HPLC determination of glutaraldehyde at g/l and mg/l concentrations, after derivatization by 2,4-dinitrophenylhydrazine and using the external standard method. At low concentrations, the reaction mixture needs to be heated and a weight ratio of 500 for the 2,4-dinitrophenylhydrazine reagent and the glutaraldehyde ensures a linear calibration curve. In contrast, high concentrations do not require heating of the reaction mixture and a weight ratio of 32 proved to be sufficient. The optimized HPLC method has been validated for both ranges of concentrations. Between 1.25 and 10 mg/l, the content can be determined by the external standard method, with a repeatability of 0.5%. The detection limit is 0.2 mg/l. Between 0.31 and 2.5 g/l, the content can also be determined by the external standard method, with a repeatability of 0.4%. Finally, statistical analysis has demonstrated that aqueous solutions of glutaraldehyde are stable for at least three days at 4 degrees C within the mg to g range.