New glycosylated porphyrins for PDT applications.

A good sensitizer for photodynamic therapy (PDT) should be a very selective reagent, which should fastly eliminate from healthy tissues. Furthermore it should have a strong absorption in the red light and good energy transfer properties to molecular oxygen to produce singlet oxygen. All these specifications imply that many second generation photosensitizers (porphyrins, chlorins, bacteriochlorins...) have been modified in order to improve their properties, but however, few have received the approval by regulatory authorities. One way to increase the selectivity of a photosensitizer is coupling it to a vector. Carbohydrate-bound porphyrins were found to be of great interest because of the specific affinity of particular carbohydrates for some tumour cells, the increasing of plasmatic life time and solubility. In this study, we report the synthesis and the photophysical properties (absorption, fluorescence, singlet oxygen formation) of new glycosylated porphyrins. Then, in vitro photocytotoxic properties were evaluated on the human colon adenocarcinoma cell line HT29.

Coumarin-like fluorescent molecular rotors for bioactive polymers probing.

Polysaccharides are interesting and often essential macromolecules but are difficult to analyse due to their lack of convenient chromophores. We propose an efficient labelling procedure for polysaccharides such as functionalized dextrans with coumarin derivatives: the fluorescent tracers present inter alia properties of emission of fluorescence dependent on the molecular environment (polarity, viscosity, temperature, pH, etc.). Hence, with in mind the understanding of cell-polysaccharide interactions, the labelled polymers were studied by in vitro tests on a line of endothelial cells sensitive to the proliferative effect of these dextran polysaccharides. Using 3D fluorescence microscopy, the fixation and internalization of fluorescent functionalized dextrans were observed in endothelial cells.

Tissue-specific pattern of variant transcripts of the human gonadotropin-releasing hormone receptor gene.

The expression pattern of the GnRH receptor was investigated in a variety of normal and neoplastic human tissues by RT-PCR-Southern blotting. In addition to the full-length cDNA (sb1), we identified two other transcripts: the first (sb2) was characterized by a 128 bp deletion as previously described; the second was an unexpected finding composed of a shorter cDNA (sb3), the sequence of which revealed a 220 bp deletion corresponding in size to exon 2. These three transcripts were found in normal pituitary and pituitary adenomas, and in granulosa tumors, but not in testis, where sb2 was lacking. Only sb1 was expressed in normal, fibrocystic and malignant breast tissue. No transcript with a full-length region was found in endometrium, intestine or lymphocytes. This is the first report that shows that splicing of the gonadotropin-releasing hormone receptor gene is tissue dependent. We also determined the intron-exon nucleotide sequence of the gene and identified an MaeIII polymorphic site in exon 1 created by a silent C453T transition found in 10% of unrelated French whites.

Molecular rotors as fluorescent probes for biological studies.

Molecular rotors, which structure can be 4-(N,N-dimethylamino)-benzene, -benzylidene and -cinnamylidene derivatives and, also, coumarine-like compounds, have photophysical characteristics which strongly depend on the environmental parameters (polarity, viscosity, temperature, etc.). In this paper, a basic knowledge on molecular fluorescent rotors will be reminded and two fields of applications using molecular fluorescent rotors as optical sensors will be described: firstly, in polymer and, more particularly to detect the formation of hydrophobic microdomains, in the case of the aggregation of amphiphilic polymers (as models for globular proteins and/or enzymes) and, secondly, in cell biology, especially in liposomes (as models for biological membranes) to follow their thermotropic behavior and in endothelial cells under 3D fluorescence microscopy.

The GnRH receptor gene is preferentially expressed in functioning gonadotroph adenomas and displays a Mae III polymorphism site.

OBJECTIVE: Given the central role of the GnRH receptor (GnRHR) in the regulation of the gonadotrophin secretion, it might be implicated directly or indirectly in the pathogenesis of gonadotroph tumours. DESIGN: We determined if GnRHR mRNA was expressed in gonadotroph tumours using RT-PCR and analysed the GnRHR gene for the presence of mutations in its coding region, using direct sequencing of PCR products. Results were analysed according to the pattern of expression of alpha, beta-FSH and beta-LH subunit (SU) genes. SUBJECTS: RNA was extracted from 20 gonadotroph tumours identified by immunohistochemistry (> 10% of stained cells): 9 adenomas were functioning (high serum gonadotrophin levels), 3 were associated with high alpha-SU levels and 8 were nonfunctioning. Genomic DNA was extracted from 64 normal subjects. RESULTS: We found GnRHR mRNA in 12 tumours (60%): 8/9 functioning (88%), 1/3 alpha-secreting (33%) and 3/8 nonfunctioning (37.5%) gonadotroph adenomas. There was a significant association between GnRHR expression and immunostaining for beta-FSH (P = 0.014). The nucleotide sequence of the amplified products was identical to that of human pituitary except for the presence, in 3 functioning adenomas, of a silent C to T transition at nucleotide 453 encoding for the serine residue situated in the second intracellular loop at position 151. Heterozygosity provided evidence that both alleles were transcribed in these tumours. This substitution creates a Mae III restriction site. Genomic DNA from normal subjects were then tested for the presence of this new polymorphism. The frequency of the heterozygosity (18.7%) was not significantly different from that found in gonadotroph tumours (25%) and this new Mae III polymorphism site cannot be used as a tumoural marker. CONCLUSION: The GnRHR gene is preferentially expressed in functioning rather than in nonfunctioning gonadotroph adenomas, but no mutations altering the coding region of the gene were found to further substantiate its role in the pathogenesis of gonadotroph tumours.

Fetal expression of GnRH and GnRH receptor genes in rat testis and ovary.

The identification of gonadal gonadotropin-releasing hormone receptors (GnRH-R) and evidence of direct inhibitory effects of GnRH agonists upon steroidogenesis in adult rat gonads, lend credence to a putative intragonadal role of a locally secreted GnRH or GnRH-like peptide. Using reverse transcription-polymerase chain reaction followed by Southern blot hybridization and sequencing, we identified, both in the ovary and in the testis of fetal and adult rats, a fully processed GnRH messenger RNA (mRNA), the sequence of which, in adult testis, was identical to that found in the hypothalamus. We also detected in the testis, but not in the ovary, a transcript containing the first intron. The ontogeny of GnRH and GnRH-R gene expression was studied in rat gonads from 14.5 to 21.5 days post-coitum (dpc), using dot blot hybridization of total RNA. During this period, the levels of cyclophilin mRNA normalized to total RNA remained unchanged. Thus, we used cyclophilin as an internal standard. GnRH mRNA was detected in the ovary at 18.5 dpc, four days later than in the testis, and similar levels were found in both sexes at birth. GnRH-R mRNA was present at 14.5 dpc in the testis and at 15.5 dpc in the ovary, with the levels at 21.5 dpc being 2.4 times higher in the testis than in the ovary. GnRH and GnRH-R mRNA levels increased in both sexes in late fetal development, but this increase appeared two days sooner in the ovary compared with the testis, thus supporting the hypothesis that expression of the GnRH and GnRH-R genes is regulated in a sex-dependent manner during fetal development. In all cases, expression of GnRH and GnRH-R preceded gonadotropin receptors in the gonads and initiation of gonadotropin secretion by the pituitary.

The genes for gonadotropin-releasing hormone and its receptor are expressed in human breast with fibrocystic disease and cancer.

While gonadotropin-releasing hormone (GnRH) or GnRH receptor (GnRHR) have been reported to exist in tissues other than brain and pituitary, there is no report concerning co-expression of GnRH and GnRHR in human breast tissues. To address this question, we have examined whether mRNA for GnRH as well as GnRHR was present in different human breast samples, by employing the reverse transcription-polymerase chain reaction (RT-PCR) protocol followed by Southern blotting of the PCR products. Coexpression of GnRH and GnRHR genes was further confirmed by dot blot hybridization using appropriate [32P]-labeled probes. We thus tested fibrocystic breast (4 cases), invasive ductal carcinomas (6 cases) and 1 adjacent non-neoplastic tissue. GnRHR and GnRH mRNAs were found in all actin-positive samples including malignant as well as nonmalignant tissues. Quantitative determinations of mRNA did not reveal significant differences between malignant and non-malignant breast samples for either GnRH or GnRHR gene expression. Our data show that neither gene was overexpressed in the breast cancer samples compared with normal breast tissue. Since GnRH agonists inhibit breast epithelial cell growth, the presence of GnRHR mRNA suggests that GnRH may specifically affect breast cell growth. Our data thus raise the possibility of an autocrine/paracrine role for GnRH in human mammary gland.

Central venous brachial catheter (P.A.S. Port TM) and catheter scanning system (Cath-Finder TM).

To assess the effectiveness and safety of an implanted portal with a central venous brachial implanted catheter, P.A.S. Port TM(P-P), and the accuracy of its Cath Finder TM tracking system (C-F), (Pharmacia Deltec) vs. radiology, a phase II multicentric study was designed. The catheter was implanted in 53 oncologic patients treated with chemotherapy and the performance of the catheter was evaluated for 3 months. No problems arose during the implantation in 77% of the cases and in all cases radiologic location of the catheter tip coincided with the C-F. We can conclude that P-P is easy to implant and to maintain in the arm and that it is well tolerated by the patients. C-F is an accurate and reliable system for locating the catheter tip. The use of both systems is an attractive alternative to the standard ones.

Fiber-optic fluorescing sensors for nitrate and nitrite detection.

Fiber-optic sensors allow remote analyses of chemical substances and they now find many applications in chemistry and biology [1,2]. The purpose of this short report is to give our first results in the development of optical-fiber chemical sensors. Among the numerous known spectrometric methods, we chose the fluorometric one, generally described as a suitable method for determining substances at the parts per million or parts per billion level, with the objective of analyzing nitrate and nitrite anions, using modifications of the fluorescence emission of suitable dyes. The detection of nitrates is based on the irreversible nitration of fluorescein, which leads to a subsequent inhibition of fluorescence emission [3]; determination of nitrites corresponds to their addition on 2,3-diaminonaphthalene, which on the contrary, improves the fluorescence emission [4]. To set up simple instrumentation, we are developing fiber-optic sensors. This consists of (i) realizing an extrinsic active optical fiber by chemical linkage of suitable fluorescent dyes on silica fiber involving silanization reaction (APTES) and chemical methods and (ii) designing an optical device which is appropriate for measurements with optical fibers. The threshold of detection, coating efficiency, and stability with time are presented.

Interaction of a phosphatidylcholine derivative of 1,6-diphenyl-1,3,5-hexatriene (DPH) with intact living cells: Steady-state fluorescence polarization and phase fluorometry studies.

The potential interest of DPH-PC was checked with a macrophagic cell line (P388D1). The uptake of DPH-PC was associated with a rapid increase in both fluorescence intensity and a slow decrease in anisotropy values. A flow cytometry comparative study with DPH revealed in both cases the existence of two cell subpopulations with different labeling levels. The analysis of fluorescence decay of DPH-PC showed two components. The fractional intensity of the main component (9.7 ns) is higher than 92%. The Lorentzian distribution of the main lifetime presents an important homogeneity. The observation that an increase in temperature induced a decrease in steady state anisotropy values but did not affect the lifetime suggests that the anisotropy variations effectively reflect modifications in the cohesion of probe micro-surroundings. A transmembrane diffusional phenomenon of a fraction of fluorescent phospholipids (205) was suggested by a study with a nonpermeant membrane quencher. The transmembrane diffusion was confirmed by extraction of the phospholipid analog with fatty acid free BSA. The use of inhibitors of endogenous phospholipase A2 showed a progressive hydrolysis of the fluorescent phospholipid. Nevertheless, the hydrolysis can be neglected in the case of short term interactions with cells (<30 min). Therefore, it can be assumed that DPH-PC can be used as a membrane probe.

Novel inhibitors and substrates of bilirubin: UDP-glucuronosyltransferase. Arylalkylcarboxylic acids.

The in vitro inhibitory potency of 20 structurally related alkanoic and arylalkanoic acids has been investigated on rat liver UDP-glucuronosyltransferase. These compounds were tested on the microsomal and purified enzyme, and a cloned cDNA expressed in COS 7 cell cultures. Among all the acids tested, 7,7,7-triphenylheptanoic acid was the most powerful inhibitor of bilirubin:UDP-glucuronosyltransferase with a lower effect on 1-naphtol, androsterone and testosterone glucuronidation. The inhibition was competitive towards the microsomal and purified bilirubin:UDP-glucuronosyltransferases with Kiapp values of 12.0 microM and 1.6 microM, respectively. Twenty analogues were examined, and the results showed that their inhibitory potency on bilirubin:UDP-glucuronosyltransferase activity was a function of at least three structural features (a) the presence of a hydrophobic triphenyl moiety; (b) the length of the aliphatic chain and (c) the presence of a carboxylic group. These inhibitors were also tested as possible substrates of UDP-glucuronosyltransferases. The strongest inhibitors were poor substrates of rat liver microsomal UDP-glucuronosyltransferases. However, 7,7,7-triphenylheptanoic acid was actively glucuronidated by purified bilirubin:UDP-glucuronosyltransferase, in contrast to its analogues with decreasing alkyl chain length. In addition, glucuronidation of this molecule was enhanced by clofibrate treatment but could not be detected in Gunn rats, which are deficient in bilirubin:UDP-glucuronosyltransferase, further indicating that the glucuronidation of this compound was catalysed by bilirubin:UDP-glucuronosyltransferase. The results suggest that 7,7,7-triphenylheptanoic acid may be a useful structural probe to investigate the molecular basis of glucuronidation of bilirubin and carboxylic acids.

Farnesylacetone, a sesquiterpenic hormone of Crustacea, inhibits electron transport in isolated rat liver mitochondria.

Farnesylacetone (C18 H30 0) is a male hormone extracted from the androgenic gland of crab, Carcinus maenas. Appropriate enzymatic assays, as well as spectrophotometric studies, indicate that micromolar concentrations of farnesylacetone interact with the electron transport pathway of rat liver mitochondria. By the use of artificial electron donors and electron acceptors, it is shown that farnesylacetone immediately inhibits the electron transfer within complex I (NADH ubiquinone reductase activity) and complex II (succinate ubiquinone reductase activity). It is proposed that farneylacetone could interact with these two complexes of the respiratory chain at the level of the iron-sulfur centers implicated in the dehydrogenase activities. These observations are compared with the results obtained with terpenic molecules which interact with mitochondrial respiration.

Inhibition of bilirubin UDPglucuronosyltransferase activity by triphenylacetic acid and related compounds.

Bilirubin UDPglucuronosyltransferase of rat or human liver microsomes was inhibited, in vitro, by triphenylacetic acid and by structurally related arylcarboxylic acids. This inhibition appeared to be competitive towards bilirubin, and mixed-type towards UDPglucuronic acid. A decrease in the number of phenyl rings or the absence of the carboxyl group in the molecule gave structures which did not affect enzyme activity, showing that both the triphenyl moiety and the carboxyl group were necessary for the inhibition. On the other hand, successive additions of methylene groups in the aliphatic chain progressively increased inhibitory potency. Kappi,bilirubin for triphenylacetic acid was 96 microM compared with 5 microM for 7,7,7-triphenylheptanoic acid. The inhibition of bilirubin UDPglucuronosyltransferase was not due to displacement of bilirubin from albumin. On the basis of these results an attempt was made to delineate the molecular events leading to glucuronidation of bilirubin.

[Brachial plexus block in children. Approach through the brachial canal]. / Bloc du plexus brachial chez l'enfant. Abord par le canal brachial.

This study included 35 children (average age: 8 years) undergoing surgery of the upper limb under brachial plexus block. The brachial plexus was approached by the brachial canal route, which is a simple, rapid and efficient way (34 were successful). The main advantage of this technique was the avoidance, in most children, of general anaesthesia as a complement. In addition, postoperative analgesia was satisfactory in all cases. In spite of large doses and volumes of lidocaine and bupivacaine used with this technique, no complication was observed.

Synthesis of a novel series of (aryloxy)propanolamines: new selective beta 2-blocking agents.

A new family of beta-blocking drugs is described. The originality of the new molecules lies in their functionalized hydrophobic folded structure, the basic part of which contains a benzocyclobutene ring. Excellent beta 2-blocker selectivity has been obtained with some of these compounds. Interestingly, this selectivity was not modified toward beta 1-blocker activity by introduction of the usual beta 1 inducer groups.