Developmental exposure to the A6-pesticide causes changes in tyrosine hydroxylase gene expression, neurochemistry, and locomotors behavior in larval zebrafish

In recent years, the increase in the synthesis of biopesticides for alternative agricultural uses has necessitated the study of their impacts. Among these compounds, several of them are known to exert endocrine-disrupting effects causing deregulation of a variety of physiological functions affecting cell signaling pathways involved in neural cell differentiation leading to developmental neurotoxicity. In this current paper, we thus determined the impact of the biopesticide A6 on zebrafish larvae, which is structurally linked to estrogenic endocrine disruptors. The objective of this study was to define the toxicity of A6, the mechanisms responsible, and to evaluate its effects on the locomotors activity at nanomolar concentrations (0, 0.5, 5, and 50 nM). We show through its blue fluorescence properties that A6 accumulates in different parts of the body as intestine, adipose tissue, muscle, yolk sac and head. We display also that A6 disrupt the development and affects the function of the central nervous system, especially the expression of tyrosine hydroxylase (TH) in dopaminergic neurons. We studied whether A6 disturbs the target genes expression and recorded that it downregulated genes embroiled in TH expression, suggesting that A6's neurotoxic effect may be the result of its binding propinquity to the estrogen receptor.

Ethinylestradiol (EE2) residues from birth control pills impair nervous system development and swimming behavior of zebrafish larvae

The ubiquitous use of ethinylestradiol (EE2), an active constituent of birth control preparations, results in continuous release of this synthetic estrogen to surface waters. Many studies document the untoward effects of EE2 on the endocrine system of aquatic organisms. Effects of environmental EE2 on the nervous system are still poorly documented. We studied effects of pico- to nanomolar concentrations of EE2 on early nervous system development of zebrafish larvae. EE2 disrupted axonal nerve regeneration and hair cell regeneration up to 50%. Gene expression in larval brain tissues showed significantly upregulated expression of target genes, such as estrogen and progesterone receptors, and aromatase B. In contrast, downregulation of the tyrosine hydroxylase, involved in the synthesis of neurotransmitters, occurred concomitant with diminution of proliferating cells. Overall, the size of exposed fish larvae decreased by 25% and their swimming behavior was modified compared to non-treated larvae. EE2 interferes with nervous system development, both centrally and peripherally, with negative effects on regeneration and swimming behavior. Survival of fish and other aquatic species may be at risk in chronically EE2-contaminated environments.

Enhanced brain expression of genes related to cell proliferation and neural differentiation is associated with cortisol receptor expression in fishes

Stress enhances or inhibits neurogenesis in mammals and some fish species. The link between the two processes is still unclear. Most studies have been performed in very specific stressful or altered environments. Despite the known inter-individual divergence in coping abilities within populations, the relationship between the stress axis and neurogenesis has never been addressed in unstressed individuals. Here we correlate brain expression of the pcna (proliferating cell nuclear antigen) and neurod1 (neurogenic differentiation factor 1) genes, two markers of neurogenesis, with transcripts of cortisol receptors in three fish species living in very distinct environments. Within the three species, individuals with the highest expression of neurogenesis genes were also those that expressed the high levels of cortisol receptors. Based on these correlations and the hypothesis that mRNA levels are proxies of protein levels, we hypothesize that within unstressed animals, individuals sensitive to cortisol perceive a similar environment to be more stimulating, leading to increased neurogenesis. Although it is difficult to determine whether it is sensitivity to cortisol that affects neurogenesis capacities or the opposite, the proposed pathway is a potentially fruitful avenue that warrants further mechanistic experiments.

In mammalian foetal testes, SOX9 regulates expression of its target genes by binding to genomic regions with conserved signatures

In mammalian embryonic gonads, SOX9 is required for the determination of Sertoli cells that orchestrate testis morphogenesis. To identify genetic networks directly regulated by SOX9, we combined analysis of SOX9-bound chromatin regions from murine and bovine foetal testes with sequencing of RNA samples from mouse testes lacking Sox9. We found that SOX9 controls a conserved genetic programme that involves most of the sex-determining genes. In foetal testes, SOX9 modulates both transcription and directly or indirectly sex-specific differential splicing of its target genes through binding to genomic regions with sequence motifs that are conserved among mammals and that we called ‘Sertoli Cell Signature’ (SCS). The SCS is characterized by a precise organization of binding motifs for the Sertoli cell reprogramming factors SOX9, GATA4 and DMRT1. As SOX9 biological role in mammalian gonads is to determine Sertoli cells, we correlated this genomic signature with the presence of SOX9 on chromatin in foetal testes, therefore equating this signature to a genomic bar code of the fate of foetal Sertoli cells. Starting from the hypothesis that nuclear factors that bind to genomic regions with SCS could functionally interact with SOX9, we identified TRIM28 as a new SOX9 partner in foetal testes.

Neurotoxicity of a Biopesticide Analog on Zebrafish Larvae at Nanomolar Concentrations

Despite the ever-increasing role of pesticides in modern agriculture, their deleterious effects are still underexplored. Here we examine the effect of A6, a pesticide derived from the naturally-occurring α-terthienyl, and structurally related to the endocrine disrupting pesticides anilinopyrimidines, on living zebrafish larvae. We show that both A6 and an anilinopyrimidine, cyprodinyl, decrease larval survival and affect central neurons at micromolar concentrations. Focusing on a superficial and easily observable sensory system, the lateral line system, we found that defects in axonal and sensory cell regeneration can be observed at much lower doses, in the nanomolar range. We also show that A6 accumulates preferentially in lateral line neurons and hair cells. We examined whether A6 affects the expression of putative target genes, and found that genes involved in apoptosis/cell proliferation are down-regulated, as well as genes reflecting estrogen receptor activation, consistent with previous reports that anilinopyrimidines act as endocrine disruptors. On the other hand, canonical targets of endocrine signaling are not affected, suggesting that the neurotoxic effect of A6 may be due to the binding of this compound to a recently identified, neuron-specific estrogen receptor.

Intestinal epithelial stem cells do not protect their genome by asymmetric chromosome segregation

The idea that stem cells of adult tissues with high turnover are protected from DNA replication-induced mutations by maintaining the same 'immortal' template DNA strands together through successive divisions has been tested in several tissues. In the epithelium of the small intestine, the provided evidence was based on the assumption that stem cells are located above Paneth cells. The results of genetic lineage-tracing experiments point instead to crypt base columnar cells intercalated between Paneth cells as bona fide stem cells. Here we show that these cells segregate most, if not all, of their chromosomes randomly, both in the intact and in the regenerating epithelium. Therefore, the 'immortal' template DNA strand hypothesis does not apply to intestinal epithelial stem cells, which must rely on other strategies to avoid accumulating mutations.

It has been proposed that stem cells use nonrandom chromosome segregation to avoid the accumulation of replication-induced mutations. Here, the authors examine intestinal epithelial stem-cell division and show, using label exclusion and retention assays, that the cells segregate their chromosomes randomly.

Bioavailability of diazepam after intramuscular injection of its water-soluble prodrug alone or with atropine-pralidoxime in healthy volunteers

BACKGROUND AND PURPOSE

The aim of this study was to assess the relative bioavailability of diazepam after administration of diazepam itself or as a water-soluble prodrug, avizafone, in humans.

EXPERIMENTAL APPROACH

The study was conducted in an open, randomized, single-dose, three-way, cross-over design. Each subject received intramuscular injections of avizafone (20 mg), diazepam (11.3 mg) or avizafone (20 mg) combined with atropine (2 mg) and pralidoxime (350 mg) using a bi-compartmental auto-injector (AIBC). Plasma concentrations of diazepam were quantified using a validated LC/MS-MS assay, and were analysed by both a non-compartmental approach and by compartmental modelling.

KEY RESULTS

The maximum concentration (C(max)) of diazepam after avizafone injection was higher than that obtained after injection of diazepam itself (231 vs. 148 ng.mL(-1)), while area under the curve (AUC) values were equal. Diazepam concentrations reached their maximal value faster after injection of avizafone. Injection of avizafone with atropine-pralidoxime (AIBC) had no effect on diazepam C(max) and AUC, but the time to C(max) was increased, relative to avizafone injected alone. According to the Akaike criterion, the pharmacokinetics of diazepam after injection as a prodrug was best described as a two-compartment with zero-order absorption model. When atropine and pralidoxime were injected with avizafone, the best pharmacokinetic model was a two-compartment with a first-order absorption model.

CONCLUSION AND IMPLICATIONS

Diazepam had a faster entry to the general circulation and achieved higher C(max) after injection of prodrug than after the parent drug. Administration of avizafone in combination with atropine and pralidoxime by AIBC had no significant effect on diazepam AUC and C(max).

A 20-amino acid module of protein kinase C{epsilon} involved in translocation and selective targeting at cell-cell contacts

In the pituitary gland, activated protein kinase C (PKC) isoforms accumulate either selectively at the cell-cell contact (alpha and epsilon) or at the entire plasma membrane (beta1 and delta). The molecular mechanisms underlying these various subcellular locations are not known. Here, we demonstrate the existence within PKCepsilon of a cell-cell contact targeting sequence (3CTS) that, upon stimulation, is capable of targeting PKCdelta, chimerin-alpha1, and the PKCepsilon C1 domain to the cell-cell contact. We show that this selective targeting of PKCepsilon is lost upon overexpression of 3CTS fused to a (R-Ahx-R)(4) (where Ahx is 6-aminohexanoic acid) vectorization peptide, reflecting a dominant-negative effect of the overexpressed 3CTS on targeting selectivity. 3CTS contains a putative amphipathic alpha-helix, a 14-3-3-binding site, and the Glu-374 amino acid, involved in targeting selectivity. We show that the integrity of the alpha-helix is important for translocation but that 14-3-3 is not involved in targeting selectivity. However, PKCepsilon translocation is increased when PKCepsilon/14-3-3 interaction is abolished, suggesting that phorbol 12-myristate 13-acetate activation may initiate two sets of PKCepsilon functions, those depending on 14-3-3 and those depending on translocation to cell-cell contacts. Thus, 3CTS is involved in the modulation of translocation via its 14-3-3-binding site, in cytoplasmic desequestration via the alpha-helix, and in selective PKCepsilon targeting at the cell-cell contact via Glu-374.

Delivery of steric block morpholino oligomers by (R-X-R)4 peptides: structure-activity studies

Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)₄ (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)₄–PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure–activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs.

Peptide-based delivery of nucleic acids: design, mechanism of uptake and applications to splice-correcting oligonucleotides

CPPs (cell-penetrating peptides) have given rise to much interest for the delivery of biomolecules such as peptides, proteins or ONs (oligonucleotides). CPPs and their conjugates were initially thought to translocate through the cell membrane by a non-endocytotic mechanism which has recently been re-evaluated. Basic-amino-acid-rich CPPs first interact with cell-surface proteoglycans before being internalized by endocytosis. Sequestration and degradation in endocytotic vesicles severely limits the cytoplasmic and nuclear delivery of the conjugated biomolecules. Accordingly, splicing correction by CPP-conjugated steric-block ON analogues is inefficient in the absence of endosomolytic agents. New arginine-rich CPPs allowing efficient splicing correction by conjugated PNAs (peptide nucleic acids) or PMO (phosphorodiamidate morpholino oligomer) steric blockers in the absence of endosomolytic agents have recently been defined in our group and are currently being characterized. They offer promising leads for the development of efficient cellular delivery vectors for therapeutic steric-block ON analogues.

Efficient splicing correction by PNA conjugation to an R6-Penetratin delivery peptide

Sequence-specific interference with the nuclear pre-mRNA splicing machinery has received increased attention as an analytical tool and for development of therapeutics. It requires sequence-specific and high affinity binding of RNaseH-incompetent DNA mimics to pre-mRNA. Peptide nucleic acids (PNA) or phosphoramidate morpholino oligonucleotides (PMO) are particularly suited as steric block oligonucleotides in this respect. However, splicing correction by PNA or PMO conjugated to cell penetrating peptides (CPP), such as Tat or Penetratin, has required high concentrations (5-10 microM) of such conjugates, unless an endosomolytic agent was added to increase escape from endocytic vesicles. We have focused on the modification of existing CPPs to search for peptides able to deliver more efficiently splice correcting PNA or PMO to the nucleus in the absence of endosomolytic agents. We describe here R6-Penetratin (in which arginine-residues were added to the N-terminus of Penetratin) as the most active of all CPPs tested so far in a splicing correction assay in which masking of a cryptic splice site allows expression of a luciferase reporter gene. Efficient and sequence-specific correction occurs at 1 muM concentration of the R6Pen-PNA705 conjugate as monitored by luciferase luminescence and by RT-PCR. Some aspects of the R6Pen-PNA705 structure-function relationship have also been evaluated.

Chemical modifications to improve the cellular uptake of oligonucleotides

Specific control of gene expression by synthetic oligonucleotides (ON) is now widely used for target validation but clinical applications are limited by ON bioavailability. Moreover, most currently used strategies for physical and chemical delivery cannot be easily implemented in vivo. This article reviews new strategies which appear promising for ON delivery. The first part deals with ON chemical modifications aiming at improving cellular uptake as for instance the grafting of cationic groups on the ON backbone. The second part concerns ON conjugation to cell penetrating peptides.

Lipoplex and peptide-based strategies for the delivery of steric-block oligonucleotides

Synthetic oligonucleotides offer interesting prospects for the control of gene expression but clinical applications have been severely limited by their poor bioavailability. Cationic lipids have been widely used for the delivery of charged oligonucleotide (ON) analogues but most of the commercial formulations are toxic and poorly stable in the presence of serum proteins. We have developed a DOGS/DOPE liposome formulation named DLS (for delivery liposomal system), that allows for the efficient nuclear delivery of negatively charged antisense ON analogues as monitored by fluorescence microscopy and by their ability to correct deficient pre-mRNA splicing, even in serum-supplemented cell culture. Uncharged DNA mimics such as peptide nucleic acids (PNA), or phosphorodiamidate morpholino (PMO) ON are particularly interesting for their high metabolic stability and affinity for complementary RNA targets but they cannot be delivered with cationic lipids. Cell penetrating peptides (CPP), such as Tat or penetratin, have been used widely as conjugates for the delivery of various biomolecules and might be appropriate for neutral ON analogues. However, entrapment within endocytic vesicles severely limits the efficiency of PNA delivery by CPPs in the absence of endosomolytic drugs, such as chloroquine. The conjugation of new arginine-rich CPPs to PNA allows efficient nuclear delivery in the absence of chloroquine as monitored in a splicing correction assay. Both strategies have their advantages but DLS-mediated delivery remains more efficient than CPP delivery for the nuclear targeting of splice correcting ON analogues in vitro.

Vectorization of morpholino oligomers by the (R-Ahx-R)4 peptide allows efficient splicing correction in the absence of endosomolytic agents

The efficient and non-toxic nuclear delivery of steric-block oligonucleotides (ON) is a prerequisite for therapeutic strategies involving splice correction or exon skipping. Cationic cell penetrating peptides (CPPs) have given rise to much interest for the intracellular delivery of biomolecules, but their efficiency in promoting cytoplasmic or nuclear delivery of oligonucleotides has been hampered by endocytic sequestration and subsequent degradation of most internalized material in endocytic compartments. In the present study, we compared the splice correction activity of three different CPPs conjugated to PMO(705), a steric-block ON targeted against the mutated splicing site of human beta-globin pre-mRNA in the HeLa pLuc705 splice correction model. In contrast to Tat48-60 (Tat) and oligoarginine (R(9)F(2)) PMO(705) conjugates, the 6-aminohexanoic-spaced oligoarginine (R-Ahx-R)(4)-PMO(705) conjugate was able to promote an efficient splice correction in the absence of endosomolytic agents. Our mechanistic investigations about its uptake mechanisms lead to the conclusion that these three vectors are internalized using the same endocytic route involving proteoglycans, but that the (R-Ahx-R)(4)-PMO(705) conjugate has the unique ability to escape from lysosomial fate and to access to the nuclear compartment. This vector, which has displays an extremely low cytotoxicity, the ability to function without chloroquine adjunction and in the presence of serum proteins. It thus offers a promising lead for the development of vectors able to enhance the delivery of therapeutic steric-block ON in clinically relevant models.

LC–UV and LC–MS evaluation of stress degradation behaviour of avizafone

It has been known for many years that benzodiazepine compounds effectively antagonize seizures induced by organophosphorous nerve agents. In the event of poisoning, a combination of three drugs is commonly used: an anticholinergic drug (e.g. atropine), an oxime used as cholinesterase reactivator (e.g. pralidoxime or HI-6) and an anticonvulsant (i.e. benzodiazepine). Most of anticholinergics and oximes are freely soluble in water, whereas many benzodiazepines are not. However, a water-soluble prodrug form of diazepam, avizafone, has been adopted by French armed forces for the immediate treatment of nerve agent seizure. The degradation behaviour of this new drug was investigated under different stress degradation conditions (hydrolytic, oxidative, photolytic and thermal) as recommended by International Conference on Harmonization. Successful separation of the active pharmaceutical ingredient from decomposition products formed under stress conditions was achieved using liquid chromatography. The method was validated with respect to specificity, linearity, precision and accuracy.

[In vitro studies of factors possibly influencing the performance of latex condoms]

Male condoms are undoubtedly the best protection against sexually transmitted diseases. The French Military Health Service buys condoms from civilian manufacturers using a public purchasing process. This process includes strict technical analysis that allows selection of the best supplier. In addition each batch of condoms delivered to French armed forces undergoes quality testing in the laboratory of the Armed Services Central Pharmacy before being distributed to troops. Despite these strict control measures, several isss remain unclear. One issue involves the shelf life of condoms stored in warm humid tropical conditions. Another issue involves the effect of lubricants on condom quality. The purpose of this report is to describe a study designed to gain insight into these two issues. This study was conducted by the Armed Services Central Pharmacy in colaboration with the Procuremnt and Central Establishment Directorate. Findings showed that stage conditions have no negative effects on the intrinsic physico-chemial properties of condoms supplied by two different manufacturers. Conversely use of inadequate lubricants (alimentary or cosmetic compounds) appeared to have extremely deleterious effects on condom quality. Laboratory tests showed that lubricants composed mainly of fatty acids dramatically decreased the effectiveness of condoms.

Chiral separation of atropine by high-performance liquid chromatography

The separation and quantitation of the enantiomers and also the determination of the enantiomeric purity are now current and indispensable tasks for the pharmaceutical analysis. Among the various techniques, liquid chromatography remains the best modality owing to several advantages. High speed, sensitivity, and reproducible results make LC the method of choice in almost all laboratories. Phases that contain alpha1-acid glycoprotein as chiral selector are suitable for separation of charged and uncharged enantiomers with widely different structure. Atropine is widely used as parasympatolytic, anticholinergic and antiemetic drugs. It is one of the preferred antidote for immediate management of toxicity associated with nerve agents. Stereoselective separation was achieved with a prepacked alpha1-acid glycoprotein column without any derivatization procedure. The liquid chromatography system is coupled to mass spectrometry with an atmospheric pressure chemical ionization interface in the positive-ion mode. The chromatographed analytes are detected in selective ion monitoring after optimisation using factorial experimental design. Small amount of enantiomeric composition can be evaluated either by MS or by UV spectrometry (less than 5%).

Improved Brain Uptake and Pharmacological Activity Profile of Morphine-6-Glucuronide Using a Peptide Vector-Mediated Strategy

Morphine-6-glucuronide (M6G), an active metabolite of morphine, has been shown to have significantly attenuated brain penetration relative to that of morphine. Recently, we have demonstrated that conjugation of various drugs to peptide vectors significantly enhances their brain uptake. In this study, we have conjugated morphine-6-glucuronide to a peptide vector SynB3 to enhance its brain uptake and its analgesic potency after systemic administration. We show by in situ brain perfusion that vectorization of M6G (Syn1001) markedly enhances the brain uptake of M6G. This enhancement results in a significant improvement in the pharmacological activity of M6G in several models of nociception. Syn1001 was about 4 times more potent than free M6G (ED(50) of 1.87 versus 8.74 micromol/kg). Syn1001 showed also a prolonged duration of action compared with free M6G (300 and 120 min, respectively). Furthermore, the conjugation of M6G results in a lowered respiratory depression, as measured in a rat model. Taken together, these data strongly support the utility of peptide-mediated strategies for improving the efficacy of drugs such as M6G for the treatment of pain.

Peptide-vector strategy bypasses P-glycoprotein efflux, and enhances brain transport and solubility of paclitaxel

We present the results obtained with paclitaxel coupled to a peptide-vector SynB3 (PAX-OSUC-SynB3), showing that this peptide-vector enhances the solubility of paclitaxel and its brain uptake in mice using the in situ brain perfusion model. We also show by the in situ brain perfusion in P-glycoprotein (P-gp)-deficient and wild-type mice that vectorized paclitaxel bypasses the P-gp present at the luminal side of the blood-brain barrier. The effect of the vectorized paclitaxel on various cancer cells was not significantly different from that of free paclitaxel. These results indicate that vectorization of paclitaxel may have significant potential for the treatment of brain tumors.

2-Pyrrolinodoxorubicin and its peptide-vectorized form bypass multidrug resistance

A well-known mechanism leading to the emergence of multidrug-resistant tumor cells is the overexpression of P-glycoprotein, which is capable of lowering intracellular drug concentrations. In the present study, we tested the capability of 2-pyrrolinodoxorubicin (p-DOX), a highly potent derivative of DOX, to bypass multidrug resistance. The accumulation, intracellular distribution and cytotoxicity of p-DOX were tested in two cell lines (K562 and A2780) and their DOX-resistant counterparts (K562/ADR and A2780/ADR). Cellular accumulation and cytotoxicity were dramatically lowered for DOX in resistant cell lines, in comparison with non-resistant cells. In contrast, cellular accumulation, intracellular distribution and cytotoxicity of p-DOX were independent of the nature of the cell lines. The p-DOX showed potent dose-dependent inhibition of cell growth against resistant cells as compared with DOX. After treatment of resistant cells with verapamil, the intracellular levels of DOX were markedly increased and consequent cytotoxicity improved. In contrast, treatment of resistant cells with verapamil did not cause any further enhancement of cell uptake or an increase in the cytotoxic effect of the derivative p-DOX, indicating that the compound bypasses the P-glycoprotein. Finally, we show that vectorization of p-DOX by a peptide vector (SynB3) which has been shown to enhance the brain uptake of DOX and to decrease its heart accumulation does not affect this property. These results indicate that p-DOX and its vectorized form are potent and effective in overcoming multidrug resistance.

Improved brain uptake and pharmacological activity of dalargin using a peptide-vector-mediated strategy

The blood-brain barrier restricts the passage of substances into the brain. Neuropeptides, such as enkephalins, cannot be delivered into the brain when given systemically because of this barrier. Therefore, there is a need to develop efficient transport systems to deliver these drugs to the brain. Recently, we have demonstrated that conjugation of doxorubicin or penicillin to peptide vectors significantly enhances their brain uptake. In this study, we have conjugated the enkephalin analog dalargin with two different peptide vectors, SynB1 and SynB3, to improve its brain delivery and its pharmacological effect. We show by in situ brain perfusion that vectorization markedly enhances the brain uptake of dalargin. We also show using the hot-plate model that this enhancement in brain uptake results in a significant improvement in the observed antinociceptive effect of dalargin. These results support the usefulness of peptide-mediated strategies for improving the availability and efficacy of central nervous system drugs.

Induction of antigen-specific CTL responses using antigens conjugated to short peptide vectors

Linear peptides (SynB vectors) with specific sequence motifs have been identified that are capable of enhancing the transport of a wide range of molecules into cells. These peptide vectors have been used to deliver exogenous peptides and protein Ags across the cell membrane and into the cytoplasm of cells. Specifically, in vitro analysis indicated that these SynB peptides enhanced the uptake of two 9-mer peptide Ags, NP(147-155) and Mtb(250-258) (T cell epitopes of influenza nucleoprotein and Mycobacterium tuberculosis, respectively) and the M. tuberculosis Ag Mtb8.4 protein, into K562 cells when covalently linked to the respective Ags. Furthermore, selected SynB vectors, when conjugated to these same Ags and used as immunogens, resulted in considerably enhanced Ag-specific CTL responses. Several SynB vectors were tested and resulted in varying levels of cellular uptake. The efficiency of uptake correlated with the ability of the SynB construct to deliver each epitope in vivo and induce specific CTL responses in mice. These data suggest that peptide vectors, such as SynB that transport target Ags across the cell membrane in a highly efficient manner, have significant potential for vaccine delivery.

Improved brain delivery of benzylpenicillin with a peptide-vector-mediated strategy

Previous studies from our laboratory have demonstrated that the coupling of doxorubicin with SynB1 vector dramatically increases its brain uptake. In the present study, we have evaluated the broad application of this approach using another molecule: benzylpenicillin (B-Pc). We, therefore, have coupled the beta-lactam antibiotic B-Pc with SynB1 and assessed its ability to cross the blood-brain barrier (BBB) using the in situ rat brain perfusion method. We first confirmed the very low brain uptake of free radiolabeled B-Pc. When B-Pc was coupled to SynB1, its uptake in brain was increased by a factor of 7, without compromising the BBB integrity. The vectorised B-Pc was distributed in all the gray areas assessed (frontal, parietal, and occipital cortex, thalamus, hippocampus, and striatum). Moreover, using a wash-out procedure and a capillary depletion method, we have shown that the radiolabeled B-Pc was associated mainly with brain parenchyma. In summary, this study demonstrates the successful application of the use of SynB1 vector for the transport of B-Pc across the BBB.

Dual-mode gradient HPLC procedure for the simultaneous determination of chloroquine and proguanil

In order to assay the antipaludic capsule of the Service de Santé des Armées (SSA), that contains two antimalarial drugs, i.e. chloroquine sulfate (CQS, cp1) and proguanil hydrochloride (PGH, cp5), a HPLC procedure was developed. A reversed-phase ion-pair high-performance liquid chromatography (HPLC) method with an ultraviolet detection at 254 nm was set up and validated. Elution system includes programming of both organic concentration and flow-rate known as 'dual-mode gradient'. This method allows the simultaneous determination of both active compounds and separation of four process related substances. The method is simple, rapid, selective and accurate, and the precision is good with an inter- and intra-assay of <2%. The sensitivity is particularly suitable for pharmaceutical quality control.

Physico-chemical requirements for cellular uptake of pAntp peptide. Role of lipid-binding affinity

The pAntp peptide, corresponding to the third helix of the Antennapedia homeodomain, is internalized by a receptor-independent process into eucaryotic cells. The precise mechanism of entry remains unclear but the interaction between the phospholipids of plasma membrane and pAntp is probably involved in the translocation process. In order to define the role of peptide-lipid interaction in this mechanism and the physico-chemical properties that are necessary for an efficient cellular uptake, we have carried out an Ala-Scan mapping. The peptides were labeled with a fluorescent group (7-nitrobenz-2-oxo-1,3-diazol-4-yl-; NBD) and their cell association was measured by flow cytometry. Furthermore, we determined the fraction of internalized peptide by using a dithionite treatment. Comparison between cell association and cell uptake suggests that the affinity of pAntp for the plasma membrane is required for the import process. To further investigate which are the physico-chemical requirements for phospholipid-binding of pAntp, we have determined the surface partition coefficient of peptides by titrating them with phospholipid vesicles having different compositions. In addition, we estimated by circular dichroism the conformation adopted by these peptides in a membrane-mimetic environment. We show that the phospholipid binding of pAntp depends on its helical amphipathicity, especially when the negative surface charge density of phospholipid vesicles is low. The cell uptake of pAntp, related to lipid-binding affinity, requires a minimal hydrophobicity and net charge. As pAntp does not seem to translocate through an artificial phospholipid bilayer, this might indicate that it could interact with other cell surface components or enters into cells by a nonelucidated biological mechanism.

Doxorubicin-peptide conjugates overcome multidrug resistance

A well-known mechanism leading to the emergence of multidrug-resistant tumor cells is the overexpression of P-glycoprotein (P-gp), which is capable of lowering intracellular drug concentrations. To overcome this problem, we tested the capability of two peptide vectors that are able to cross cellular membranes to deliver doxorubicin in P-gp-expressing cells. The antitumor effect of peptide-conjugated doxorubicin was tested in human erythroleukemic (K562/ ADR) resistant cells. The conjugate showed potent dose-dependent inhibition of cell growth against K562/ADR cells as compared with doxorubicin alone. Doxorubicin exhibited IC50 concentrations of 65 microM in the resistant cells, whereas vectorized doxorubicin was more effective with IC50 concentrations of 3 microM. After treatment of the resistant cells with verapamil, the intracellular levels of doxorubicin were markedly increased and consequent cytotoxicity was improved. In contrast, treatment of resistant cells with verapamil did not cause any further enhancement in the cell uptake nor in the cytotoxic effect of the conjugated doxorubicin, indicating that the conjugate bypasses the P-gp. Finally, we show by the in situ brain perfusion method in P-gp-deficient and competent mice that vectorized doxorubicin bypasses the P-gp present at the luminal site of the blood-brain barrier. These results indicate that vectorization of doxorubicin with peptide vectors is effective in overcoming multidrug resistance.

Enhanced delivery of doxorubicin into the brain via a peptide-vector-mediated strategy: saturation kinetics and specificity

Doxorubicin delivery to the brain is often restricted because of the poor transport of this therapeutic molecule through the blood-brain barrier (BBB). To overcome this problem, we have recently developed a technology, Pep:trans, based on short natural-derived peptides that are able to cross efficiently the BBB without compromising its integrity. In this study, we have used the in situ mouse brain perfusion method to evaluate the brain uptake of free and vectorized doxorubicin. Doxorubicin was coupled covalently to small peptide vectors: L-SynB1 (18 amino acids), L-SynB3 (10 amino acids), and its enantio form D-SynB3. We first confirmed the very low brain uptake of free radiolabeled doxorubicin, which is most likely due to the efflux activity of the P-glycoprotein at the level of the BBB. Vectorization with either L-SynB1, L-SynB3, or D-SynB3 significantly increased the brain uptake of doxorubicin (about 30-fold). We also investigated the mechanism of transport of vectorized doxorubicin. We show that vectorized doxorubicin uses a saturable transport mechanism to cross the BBB. The effect of poly(L-lysine) and protamine, endocytosis inhibitors, on the transport across the brain was also investigated. Both inhibitors reduced the brain uptake of vectorized doxorubicin in a dose-dependent manner. These studies indicate that the transport of vectorized doxorubicin appears to occur via an adsorptive-mediated endocytosis.

New advances in the transport of doxorubicin through the blood-brain barrier by a peptide vector-mediated strategy

Many therapeutic drugs are excluded from entering the brain, due to their lack of transport through the blood-brain barrier (BBB). To overcome this problem, we have developed a novel method in which short, naturally derived peptides (16-18 amino acids) cross the cellular membranes of the BBB with high efficiency and without compromising its integrity. The antineoplastic agent doxorubicin (dox) was coupled covalently to two peptides, D-penetratin and SynB1. The ability of dox to cross the BBB was studied using an in situ rat brain perfusion technique and also by i.v. injection in mice. In the brain perfusion studies, we first confirmed the very low brain uptake of free radiolabeled dox because of the efflux activity of P-glycoprotein at the BBB. By contrast, we have demonstrated that when dox is coupled to either the D-penetratin or SynB1 vectors, its uptake was increased by a factor of 6, suggesting that the vectorized dox bypasses P-glycoprotein. Moreover, using a capillary depletion method, we have shown that vectorization of dox led to a 20-fold increase in the amount of dox transported into brain parenchyma. Intravenous administration of vectorized dox at a dose of 2.5 mg/kg in mice led to a significant increase in brain dox concentrations during the first 30 min of postadministration, compared with free dox. Additionally, vectorization led to a significant decrease of dox concentrations in the heart. In summary, our results establish that the two peptide vectors used in this study enhance the delivery of dox across the BBB.

Stability study of a new antidote drug combination (Atropine-HI-6-Prodiazepam) for treatment of organophosphate poisoning

The main purpose of this study was to investigate the chemical stability of a new antidote combination for the treatment of organophosphate poisoning. The antidote combination was packed (enclosed) in two plastic compartments separated by a barrier film. One of them contained a powder oxime cholinesterase reactivator (HI-6-monohydrate 1-[[[4-(aminocarbonyl)pyridinio]methoxy]methyl]-2-[(hydro xyimino)meth yl]-pyridinium dichloride). The other contained an anticholinergic (Atropine) and an anticonvulsant (Prodiazepam or Avizafone (L-lysyl-N-(2-benzoyl-4-chlorophenyl)-N-methyl-glycinamide dihydrochloride) drug in a liquid mixture. The plastic compartments were mounted in an autoinjector device to study the dissolution of HI-6 by ejection of the solution. Drug analysis was performed by high-performance liquid chromatography. The results obtained after 6 months show that this new antidote combination is stable. The amount of each antidote is unchanged during the study. Some known degradation products can be detected in small amounts. The autoinjector mechanism used, gives a complete dissolution of HI-6 powder in the liquid mixture throughout the study.

The molecular biology of the flavin-containing monooxygenases of man

cDNA clones encoding five distinct members of the FMO family of man (FMOs 1, 2, 3, 4 and 5) were isolated by a combination of library screening and reverse transcription-polymerase chain reaction techniques. The deduced amino acid sequences of the human FMOs have 82-87% identity with their known orthologues in other mammal but only 51-57% similarity to each other. The hydropathy profiles of the proteins are very similar. From the calculated rate of evolution of FMOs (a 1% change in sequence per 6 million years) it would appear that individual members of the FMO gene family arose by duplication of a common ancestral gene some 250-300 million years ago. Each of the FMO genes was mapped by the polymerase chain reaction to the long arm of human chromosome 1. The localization of the FMO1 gene was further refined to 1q23-q25 by in situ hybridization of human metaphase chromosomes. RNase protection assays demonstrated that in man each FMO gene displays a distinct developmental and tissue-specific pattern of expression. In the adult, FMO1 is expressed in kidney but not in liver, whereas in the foetus its mRNA is abundant in both organs. FMO3 expression is essentially restricted to the liver in the adult and the mRNA is either absent, or present in low amounts, in foetal tissues. FMO4 is expressed more constitutively. Human FMO1 and FMO3 cDNAs were functionally expressed in prokaryotic and eukaryotic cells. FMO1 and FMO3, expressed in either system, displayed product stereoselectivity in their catalysis of the N-oxidation of the pro-chiral tertiary amines, N-ethyl-N-methylaniline (EMA) and pargyline. Both enzymes were stereoselective with respect to the production of the (-)-S-enantiomer of EMA N-oxide. But in the case of pargyline, the enzymes displayed opposite stereoselectivity, FMO1 producing solely the (+)-enantiomer and FMO3 predominantly the (-)-enantiomer of the N-oxide.

Omeprazole and lansoprazole are mixed inducers of CYP1A and CYP3A in human hepatocytes in primary culture

The ability of several gastric antiulcer drugs including lansoprazole, cimetidine and ranitidine to affect the expression of human liver microsomal cytochromes P450 comparatively to omeprazole, reported previously to be a CYP1A inducer, was evaluated in primary cultures of human hepatocytes. Poly (A)+ RNA and microsomes extracted from the cells were analyzed in Northern and Western blots with specific cDNA probes and antibodies, and assayed for form-specific monoxygenase activities. Lansoprazole induced both CYP1A1 and CYP1A2 as omeprazole and did not apparently bind to the aryl hydrocarbon receptor with high affinity. Omeprazole sulfone was not an inducer of CYP1A. Omeprazole, omeprazole sulfone and lansoprazole induced CYP3A in approximately 50% of tested cultures, whereas 100% of tested cultures responded to omeprazole and to rifampicin in terms of CYP1A and CYP3A induction, respectively. Finally, cimetidine and ranitidine were not inducers. We conclude that omeprazole and lansoprazole constitute a new class of mixed inducers of CYP1A and CYP3A in human hepatocytes in primary culture and that the induction of CYP3A in response to these molecules could be polymorphic in humans.

Induction, regulation and messenger half-life of cytochromes P450 IA1, IA2 and IIIA6 in primary cultures of rabbit hepatocytes. CYP 1A1, 1A2 and 3A6 chromosome location in the rabbit and evidence that post-transcriptional control of gene IA2 does not involve mRNA stabilization

A study on the regulation and induction of expression of cytochromes P450-IA1, IA2 and IIIA6 genes has been undertaken using primary cultures of adult rabbit hepatocytes grown in a serum-free chemically and hormonally defined medium. In 72-h-old cultures, 50 microM beta-naphthoflavone induced both IA1 and IA2 mRNA, the maximal level being reached after 4 h and 12 h, respectively. This was shown to result from an increase in the rate of transcription of gene IA1. In contrast, gene IA2 was constitutively transcribed in untreated cells, but mRNA only accumulated in the presence of beta-naphthoflavone which, however, did not affect the rate of transcription. Actinomycin D fully blocked induction of both IA1 and IA2 mRNA in response to their inducer. In untreated cells the presence of cycloheximide allowed a 'constitutive' expression of gene IA1, while in beta-naphthoflavone-treated cells, it produced a super-induction of IA1 but no modification of IA2 gene expression. Rifampicin (50 microM) strongly increased the IA1 mRNA level and rate of transcription only in cycloheximide-treated cells. Rifampicin and dexamethasone, two prototypical inducers of P450-IIIAs, induced both large and small IIIA6 mRNAs in a time-dependent fashion, the maximum level being reached after 24 h. This was related to a large increase in the rate of transcription of the gene. Cycloheximide significantly decreased the accumulation of both IIIA6 mRNAs in response to rifampicin, while actinomycin D fully blocked induction. The half-lives of IA1, IA2 and IIIA6 mRNAs were determined by two different methods, namely actinomycin D and [3H]uridine-chase experiments. In untreated cells, the half-lives for IA1, IA2 and IIIA6 mRNAs were 14 h, 16 h and 19 h, respectively when determined by the uridine chase and 18 h, 25 h and 22 h when determined by the actinomycin-D chase. These values were not modified significantly in cells treated with beta-naphthoflavone or rifampicin, indicating that neither of these inducers affected the stability of IA1 and IA2 or IIIA6 messages, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Complete sequence of cytochrome P450 3c cDNA and presence of two mRNA species with 3' untranslated regions of different lengths

Two cDNAs (pLM3c 4.1 and pLM3c 6.1) coding for rabbit cytochrome P450 3c were sequenced. cDNA 4.1 (1768 bp) exhibits an open reading frame from nucleotides 74 to 1576 encoding the 501 amino acid residues of the entire protein. cDNA 6.1 (189 bp) appears to encode the last 24 amino acids. Comparative amino acid sequence analysis indicated that P450 PCN1, PCN2, and HLp from rat and man, were 70, 67, and 73% homologous, respectively, to P450 3c. According to the cytochrome P450 nomenclature, the P450 3c gene is termed P450IIIA4. Comparison of the nucleotide sequences indicated that cDNA 6.1 was 100% homologous to cDNA 4.1. However, whereas a poly(A) tract started 23 nucleotides after the AATAAA consensus sequence in cDNA 6.1, cDNA 4.1 had a 3' untranslated region extending 101 bp beyond the polyadenylation signal, which lacked poly(A). This observation is consistent with the previous finding that both cDNA 4.1 and 6.1 hybridized with two distinct species of poly(A)RNA (1700 and 1850 bases) from rabbit liver. The extreme 3'-end 79-bp fragment of cDNA 4.1 therefore was isolated by subcloning in pUC12 (clone p18-Rsa I) and used to probe Northern blots of poly(A)RNA from control and rifampicin-treated rabbit liver. In contrast to cDNA 4.1 and 6.1, p18-Rsa I cDNA hybridized only with the largest (1850 bases) mRNA species. We conclude that rabbit liver contains two P450 3c mRNA species differing in the length of their 3' untranslated region.

Daily variations of plasma sex hormone-binding globulin binding capacity, testosterone and luteinizing hormone concentrations in healthy rested adult males

In this study the daily variations of plasma sex hormone-binding globulin (SHBG) binding capacity were measured together with plasma testosterone and luteinizing hormone (LH) concentrations in 7 healthy rested adult males. Plasma SHBG-binding capacity demonstrated a significant circadian rhythm (acrophase = 2.06 p.m.; mesor = 0.35 +/- 0.6 ng testosterone bound/100 ml; amplitude = 17% of the mesor). Plasma testosterone also showed a circadian rhythm (acrophase = 7.02 a.m.; mesor = 4.38 +/- 0.67 ng/ml; amplitude = 18% of the mesor). The free testosterone index (or the ratio between plasma testosterone and SHBG-binding capacity) was not correlated with plasma LH levels. In our hands this last parameter did not vary according to a circadian pattern. These data are discussed in terms of a feedback mechanism controlling the pituitary-testis axis regulation.

Androgen metabolism in vitro by human leukocytes, variations with sex and age

The present study was undertaken in order to examine the metabolism of androgens by isolated human leukocytes. After incubation, steroids were extracted and purified by high performance liquid chromatography (HPLC); identification and quantification of the steroid products was achieved by gas-liquid-chromatography (GLC), radio-GLC and combined gas chromatography-mass spectrometry (GC-MS) of the trimethylsilyl derivatives (TMS). Incubation in the presence of testosterone led to the formation of 4-ene-androstenedione and 5 alpha-dihydrotestosterone (5 alpha-DHT) while in the presence of 5 alpha-DHT, the products were 5 alpha-androstane-3 alpha, 17 beta-diol (5-Ad) and 5 alpha-androstane-3 beta, 17 beta-diol. The formation of these metabolites was compared in healthy males and females of two age groups. Production of 5 alpha-DHT and 5-Ad was significantly higher in males than in females. In subjects aged 75 years or more, formation of these steroids was decreased by more than half in both sexes, but the sex differences remained. This study confirms the presence in human leukocytes of 17 beta-hydroxysteroid oxydoreductase, 5 alpha-reductase and 3 alpha- and 3 beta-hydroxysteroid oxydoreductase activities.