A trypanosome oligopeptidase as a target for the trypanocidal agents pentamidine, diminazene and suramin

African trypanosomes contain a cytosolic serine oligopeptidase, called OP-Tb, that is reversibly inhibited by the active principles of three of the five most commonly used trypanocidal drugs: pentamidine, diminazene and suramin. OP-Tb was inhibited by pentamidine in a competitive manner, and by suramin in a partial, non-competitive manner. The inhibition of OP-Tb by a variety of suramin analogues correlated with the trypanocidal efficacy of these analogues (P=0.03; by paired Student's t-test). Since intracellular (therapeutic) concentrations of pentamidine and suramin are reported to reach approximately 206Ki and 15Ki respectively, we suggest that these drugs may exert part of their trypanocidal activity through the inhibition of OP-Tb.

NF279: a novel potent and selective antagonist of P2X receptor-mediated responses

8,8'-(Carbonylbis(imino-4, 1 -phenylenecarbonylimino-4,1-phenylenecarbonylimino))bis(1,3, 5-naphthalenetrisulfonic acid) (NF279) antagonized P2X receptor-mediated contractions in rat vas deferens, evoked by alpha,beta-methylene ATP (10 microM; pIC50=5.71) without affecting responses mediated via alpha1A-adrenoceptors, adenosine A1 and A2B receptors, histamine H1, muscarinic M3 and nicotinic receptors. The low inhibitory potency of NF279 on P2Y receptors in guinea-pig taenia coli (pA2=4.10) and at ecto-nucleotidases in folliculated Xenopus laevis oocytes (IC50 > 100 microM) indicates that NF279 is a novel specific and selective P2X receptor antagonist.

Suramin analogues with a 2-phenylbenzimidazole moiety as partial structure; potential anti HIV- and angiostatic drugs, 2: Sulfanilic acid-, benzenedisulfonic acid-, and naphthalenetrisulfonic acid analogues

The synthesis of suramin analogues bearing a 2-phenyl-benzimidazole moiety is described. Aminoarene sulfonic acids 2a-e are acylated with 3,4-dinitrobenzoyl chloride 3 yielding the amides 4a-e which are hydrogenated to the corresponding diamines 5a-e. These are treated with 3-nitrobenzaldehyde, yielding the azomethines 7a-e and their isomers 8a-e and 9a-e. Key step in the synthesis of the target compounds 12a-e is the oxidation of the azomethines with oxygen to the benzimidazoles 10a-e. These are hydrogenated to the amines 11a-e reacting with phosgene to yield the symmetric ureas 12a-e. Results of the anti-HIV, cytostatic, and antiangiogenic screening are presented.

Antiangiogenic and antiproliferative activity of suramin analogues

The purpose of this study was to test the ability of 70 polyanionic analogues of suramin to inhibit angiogenesis. The ID50, the dose that produced 50% inhibition of angiogenesis, was determined for suramin and each of the analogues by measuring the ability of various amounts to inhibit angiogenesis in vivo in the chick egg chorioallantoic membrane (CAM) assay. Of the 70 analogues, 11 had antiangiogenic activities similar to suramin and an additional 7 were significantly more potent than suramin. All seven of these analogues were from the naphthalenetrisulfonic acid group and contained large urea groups. The benzene sulfonic and disulfonic acid analogues were less active inhibitors of angiogenesis than the naphthalenetrisulfonic acid analogues. Replacement of the naphthalenetrisulfonic acid groups by aliphatic carboxylic acids or benzoic acid gave analogues with very little antiangiogenic activity. In subsequent experiments, the antiproliferative activity of selected analogues on basic FGF (bFGF)-stimulated growth of immortalized human microvascular endothelial cells in vitro was determined. Analogues that inhibited angiogenesis to a greater extent than suramin in the CAM assay generally showed a greater antiproliferative effect on bFGF-induced growth of human microvascular endothelial cells. These results suggest that some of the polyanionic analogues may be potent therapeutic agents for cancers and angiogenesis-dependent diseases.

Gsalpha-selective G protein antagonists

Suramin acts as a G protein inhibitor because it inhibits the rate-limiting step in activation of the Galpha subunit, i.e., the exchange of GDP for GTP. Here, we have searched for analogues that are selective for Gsalpha. Two compounds have been identified: NF449 (4,4',4",4'"-[carbonyl-bis[imino-5,1,3-benzenetriyl bis-(carbonylimino)]]tetrakis-(benzene-1,3-disulfonate) and NF503 (4, 4'-[carbonylbis[imino-3,1-phenylene-(2, 5-benzimidazolylene)carbonylimino]]bis-benzenesulfonate). These compounds (i) suppress the association rate of guanosine 5'-[gamma-thio]triphosphate ([35S]GTP[gammaS]) binding to Gsalpha-s but not to Gialpha-1, (ii) inhibit stimulation of adenylyl cyclase activity in S49 cyc- membranes (deficient in endogenous Gsalpha) by exogenously added Gsalpha-s, and (iii) block the coupling of beta-adrenergic receptors to Gs with half-maximum effects in the low micromolar range. In contrast to suramin, which is not selective, NF503 and NF449 disrupt the interaction of the A1-adenosine receptor with its cognate G proteins (Gi/Go) at concentrations that are >30-fold higher than those required for uncoupling of beta-adrenergic receptor/Gs tandems; similarly, the angiotensin II type-1 receptor (a prototypical Gq-coupled receptor) is barely affected by the compounds. Thus, NF503 and NF449 fulfill essential criteria for Gsalpha-selective antagonists. The observations demonstrate the feasibility of subtype-selective G protein inhibition.

[Diagnosis of dermatomycoses with polymerase chain reaction]

A polymerase chain reaction (PCR) assay for the detection of dermatophytes was established. The primers "TR1" and "TR2" amplify a 581 bp fragment within the gene coding for the small ribosomal subunit (185 rRNA) of fungi. PCR allowed the detection of isolates of 7 common dermatophytes and in addition several yeasts and moulds. Hybridisation with specific oligonucleotides results in the identification of dermatophytes and Candida albicans. Restriction analysis of the PCR product allowed us to distinguish between dermatophytes and yeasts or moulds. The specificity of the PCR with respect to fungi was assessed by testing human DNA collected from 42 dermis and epidermis specimens as well as DNA from selected plants and animals. To evaluate the clinical relevance of the PCR assay, 69 routinely collected skin and nail specimens were examined by PCR and culture. PCR detected dermatophytes in 35 and culture in 28 of 38 specimens that were classified as positive. Sensitivity of PCR (92%) was higher than that of culture (73%). These results show that PCR has advantages over culture for the detection of dermatophytes.

Vasoconstrictor responses via P2X-receptors are selectively antagonized by NF023 in rabbit isolated aorta and saphenous artery

1. The effects of NF023, the symmetrical 3'-urea of 8-(benzamido)naphthalene-1,3,5-trisulphonic acid), and its parent compound suramin were investigated on vasoconstrictor responses to alpha, beta-methylene ATP in rabbit isolated saphenous artery and vasodilator responses to ATP in noradrenaline-precontracted rabbit isolated thoracic aorta. 2. In rabbit isolated saphenous artery, alpha, beta-methylene ATP-induced vasoconstrictor responses via P2X-receptors were concentration-dependently and competitively antagonised by NF023 (30-300 microM; pA2 = 5.69 +/- 0.04). Suramin (100-1000 microM) also competitively blocked vasoconstrictor responses to alpha, beta-methylene ATP, albeit with lower potency (pA2 = 4.79 +/- 0.05). In contrast, NF023 (100 microM) did not significantly affect contractile responses to noradrenaline or histamine in the saphenous artery. 3. In noradrenaline-precontracted rabbit isolated thoracic aorta preparations, ATP (3-3000 microM) concentration-dependently induced relaxations via endothelium-dependent or smooth muscle P2Y-receptor subtypes. NF023 (30-300 microM) failed to block relaxant responses to ATP at endothelium-dependent P2Y-receptors, whereas suramin (100-1000 microM) did antagonise endothelium-dependent vasodilator responses to ATP. Neither NF023 (100 microM) nor suramin (300 microM) influenced vasorelaxant responses to ATP via endothelium-independent P2Y-receptors. 4. In conclusion, this study outlines the selectivity of NF023 as an effective P2X-receptor antagonist in rabbit isolated blood vessels without affecting endothelium-dependent or endothelium-independent P2Y-receptor subtypes, adrenoceptors or histamine receptors.

Rapid, highly sensitive gradient narrow-bore high-performance liquid chromatographic determination of suramin and its analogues

A high-performance liquid chromatography (HPLC) method for the determination of suramin, its precursors and analogues in aqueous solutions and in plasma samples with advantages compared to earlier methods is described. Due to the method's high sensitivity (detection limit of suramin in plasma samples: 7 ng/ml; in aqueous solutions: 5 ng/ml) and selectivity (suramin tR: 7.05 min, precursor amine 2 tR: 4.68 min), it is possible to analyze degradation products, impurities and possible metabolites of suramin besides suramin. Tetrabutylammonium hydrogensulfate (TBAHS) (5 mM) is used as ion-pairing reagent in a mixture of 36% methanol and 0.02 M phosphate buffer pH 6.5 is used as the mobile phase. After sample injection, a linear gradient from 36 to 62.9% methanol is run. A C8 stationary phase (100 x 2.1 mm I.D.) is used and ultraviolet (UV) detection at 238 nm is applied. Plasma extraction is performed with tetrabutylammonium bromide (pH 8.0) and acetonitrile. This procedure allows the determination of suramin and its precursor amine 2 in the range of 0.05-400 micrograms/ml with high precision [relative standard deviation of peak areas at 0.05 microgram/ml: 2.10% (n = 5)] and nearly complete recovery (> 96.5%). Because of the high flexibility of the chromatographic system and subsequently the universality of the method, the analysis of a broad range of suramin analogues is possible. The result of the purity check of two suramin analogues is given.

P2-purinoceptor antagonists: III. Blockade of P2-purinoceptor subtypes and ecto-nucleotidases by compounds related to suramin

Effects of suramin and five analogs or fragments of suramin were studied on contractions of the rat vas deferens elicited by alpha, beta-methylene ATP (alpha, beta-MeATP; mediated by P2X-purinoceptors), relaxations of the carbachol-precontracted guinea-pig taenia coli elicited by adenosine 5'-O-(2-thiodiphosphate) (ADP beta S; mediated by P2Y-purinoceptors), and the degradation of ATP by rat vas deferens tissue. One compound, NF023, differed from suramin by removal of two p-methylbenzamido groups, whereas another, BSt101, differed from NF023 by additional removal of the three sulphonate residues from one of the terminal naphthalene rings. The compounds all shifted the concentration-response curve of alpha, beta-MeATP in the rat vas deferens to the right and simultaneously increased the maximum of the curve. Where three concentrations were tested, the Arunlakshana-Schild regression was linear, and the slope did not differ from 1. The apparent Kd values were between 1 and 3672 microM. In the guinea-pig taenia coli, the compounds shifted the concentration-response curve of ADP beta S to the right in a parallel manner, but in the one case where three concentrations were tested, the slope of the Arunlakshana-Schild regression was lower than 1. Apparent Kd values were between 10 and 786 microM. The removal of ATP from the medium by vas deferens tissue was decreased only by suramin, NF023 and BSt101, with IC25% values between 170 and 590 microM.

Inhibition of sperm-zona binding by suramin, a potential 'lead' compound for design of new anti-fertility agents

Progress in developing new contraceptive agents, particularly for the male, is extremely slow. Here, we report on a novel property of the anti-trypanosomal drug suramin: the ability to act at the sperm-egg interface and prevent fertilization. Suramin is a polysulphonated compound that inhibits binding of capacitated mouse spermatozoa to the zona pellucida in vitro with an IC50 of 12.4 microM. The drug is only effective at the time of fertilization and is not inhibitory if gametes are pre-treated separately. Autoradiographic localization of suramin binding sites on mouse, boar and human spermatozoa shows that they are intracellular, principally in the head region. The sperm protein recognized by suramin has been identified as proacrosin which is known to interact with sulphate groups on zona glycoproteins. Zona pellucida glycoproteins do not bind suramin, suggesting that the drug blocks the ability of proacrosin/acrosin, exposed during the acrosome reaction, to mediate the secondary binding phase of spermatozoa to the zona during fertilization. Structure-based design studies have the potential to generate safe suramin mimetics that would form the basis for a new generation of non-steroidal contraceptive agents.

Stability of suramin in aqueous solution; possible implications for the search for suramin metabolites in patients

The stability of an aqueous solution of suramin has been determined. The only degradation product detectable by HPLC was the amine precursor 2. The decomposition kinetics of suramin at different temperatures are shown. Because of first order kinetics the Arrhenius equation could not be used to evaluate the decomposition data. A good correlation was obtained between the reaction constants and the temperature (r = 0.9898). After 42 days at 37 degrees C, 2 % of suramin are hydrolysed. Possible implications of our results for the search for suramin metabolites in patients are discussed.

Suramin analogues as subtype-selective G protein inhibitors

G protein alpha subunits expose specific binding sites that allow for the sequential, conformation-dependent binding of protein reaction partners, e.g., G protein beta gamma dimers, receptors, and effectors. These domains represent potential sites for binding of low-molecular-weight inhibitors. We tested the following suramin analogues as G protein antagonists: 8-(3-nitrobenzamido)-1,3,5-naphtalenetrisulfonic acid (NF007), 8-(3-(3-nitrobenzamido)benzamido)-1,3,5-naphtalenetrisulfonic++ + acid NF018), 8,8'-(carbonylbis(imino-3,1-phenylene))bis-(1,3,5-naphtalenetri sulfonic acid) (NF023), 8,8'-(carbonylbis(imino-3,1-phenylene)carbonylimino-(3,1-phe nylene))bis-(1,3, 5-naphtalenetrisulfonic acid) (NF037), and suramin. The compounds suppressed [35S]GTPgammaS binding to purified, recombinant G protein alpha subunits, an effect that is due to inhibition of GDP release. Suramin is selective for recombinant Gsalpha-s (EC50 values o f approximately 240 nM; rank order of potency, suramin > NF037 > NF023 > NF018 > NF007), whereas NF023 is selective for recombinant Gi alpha-1 and recombinant Go alpha (EC50 value of approximately 300 nM; rank order of potency, NF023 > / = NF037 > suramin >0 NF018 > NF007). Selectivity was also demonstrated on a cellular level. In rat sympathetic neurons, alpha-2-adrenergic and muscarinic receptor-dependent inhibition of the voltage-sensitive calcium current is mediated by Gi/Go, whereas inhibition by vasoactive intestinal peptide (VIP) is mediated by Gs. Calcium current inhibition by alpha2-adrenergic and muscarinic receptors was greatly reduced when 100 microM NF023 was applied intracellularly, whereas the response to VIP was unaffected; in contrast, the response to VIP was blunted only with 100 microM suramin in the recording pipette. The suramin analogues do not interfere with the interaction between alpha subunits and G protein beta gamma dimer but compete with binding of the effector. The addition of purified adenylyl cyclase reverses the inhibitory effect of suramin on the rate of [35S]GTPgammaS binding to recombinant Gsalpha-s, indicating direct competition for a common site; similarly, immunoprecipitation by an antibody directed against an epitope of the effector binding site is inhibited by suramin. Our results show that it is possible to design G protein inhibitors that target the effector binding site on the alpha subunits.

Inhibition of granulocyte-macrophage colony-stimulating factor (GM-CSF) activity by suramin and suramin analogues is correlated to interaction with the GM-CSF nucleotide-binding site

Suramin and suramin analogues strongly inhibit both nucleotide interaction with the nucleotide-binding site of granulocyte-macrophage colony-stimulating factor (GM-CSF) and bioactivity of the molecule as assessed by competition photoaffinity labeling and cell proliferation assay, respectively. The half-maximal inhibition of cell proliferation by suramin occurs at 68 +/- 2.5 microM; three suramin analogues achieved comparable activity. The degree of competitive inhibition of nucleotide-binding by these compounds and the inhibition of GM-CSF bioactivity are correlated such that the compounds show similar rank-order by both of these methods. The strong interaction of suramin and related compounds with the nucleotide-binding site may mimic nucleotide-mediated inhibition of GM-CSF bioactivity and may be an important mechanism by which suramin acts as a pharmacological anti-growth factor agent.

Antiproliferative and angiostatic activity of suramin analogues

Suramin, a polyanionic naphthylurea, represents a novel class of antineoplastic drugs with a variety of activities against tumor cell proliferation. However, its clinical use is hampered by serious toxicity. To gain more insight into structure-activity relationships of suramin, we investigated the antiproliferative action of suramin and 19 suramin analogues in vitro using 5 different human cell lines (HT29, MCF7, SW13, PC3, and T47D). In addition, for seven analogues the angiostatic potential with and without hydrocortisone was assessed using a modified chorioallantois membrane assay. Only the symmetric compounds exhibited antiproliferative action in vitro; several analogues were more active than suramin (e.g., NF031, NF037, NF326). Suramin analogues with six sulfonic acid groups showed a wide range of activity in HT29 cells (IC50 = 43-390 microM), indicating that besides the polyanionic feature, other structural elements are important (e.g., stiffness of the bridge between the two terminal naphthyl rings). Some of the smaller ureas with only four sulfonic acid groups retained significant antiproliferative activity. Compounds active in cell lines also inhibited angiogenesis in the chorioallantois membrane assay, suggesting a similar mode of action. Hydrocortisone increased the angiostatic effect of most but not all of the screened suramin analogues. These findings may guide the use of suramin analogues for improved antitumor therapy in vivo.

Detection of Epstein-Barr virus DNA in anal scrapings from HIV-positive homosexual men

Epstein-Barr virus (EBV) can infect epithelial cells as well as B lymphocytes. Infection of the male and female genital tracts has recently been demonstrated, and it has been suggested that the virus may be sexually transmissible. In our study we investigated whether EBV can be found in the anal region of sexually active homosexual men. Anal scrapings from HIV-positive homosexual men and a heterosexual control population were investigated using the polymerase chain reaction (PCR) to screen for EBV DNA. EBV DNA was detected in 8 of 27 anal samples (29.6%) from the homosexual men and 3 of 34 samples (8.8%) from the heterosexual men. Our study shows that, like the genital tract, the anal region can harbour EBV subclinically. This finding suggests that the anal region may be a reservoir for EBV and that sexual transmission of this virus may be possible.

Suramin analogs, divalent cations and ATP gamma S as inhibitors of ecto-ATPase

Ecto-nucleotidases are plasma membrane-bound enzymes that sequentially dephosphorylate extracellular nucleotides such as ATP. This breakdown of ATP and other nucleotides obscures the characterization and classification of P2 (nucleotide) receptors. We therefore studied suramin and several of its analogs, divalent cations and ATP gamma S for their ability to inhibit ecto-ATPase in human blood cells. Suramin itself and Ni2+ were the more potent, non-competitive inhibitors with micromolar affinity. ATP gamma S also displayed micromolar affinity and inhibited ecto-ATPase competitively. The data obtained with the divalent cations demonstrate that coordination of the phosphate chain but not the N7 of the adenine ring is required for the breakdown of ATP by ecto-ATPase. Divalent cations that coordinate both the phosphate chain and N7 inhibit ecto-ATPase in a non-competitive manner.

Suramin blocks the binding of interleukin-1 to its receptor and neutralizes IL-1 biological activities

This report demonstrates the ability of the anti-cancer drug suramin to interfere with the binding of interleukin (IL)-1 to its receptor and to inhibit IL-1-induced biological activities. In a radioreceptor cell based assay, suramin inhibits the binding of IL-1 alpha to several murine cell lines expressing predominantly type I and type II IL-1 receptors. Affinity cross-linking experiments using IL-1 alpha and EL-4.6.1 cells confirms that suramin inhibits the binding of the ligand to the 80 kDa IL-1 type I receptor. In contrast, suramin fails to displace significantly prebound IL-1. In a cell-free system, suramin prevents the binding of IL-1 alpha and IL-1 beta to murine and human recombinant soluble type I IL-1 receptors. For example, the IC50 for suramin inhibiting IL-1 alpha and IL-1 beta binding to soluble human IL-1 receptor were 204 microM and 186 microM, respectively. The suramin analogues, NF-058 and NF-103 (which bear the same number of sulfate groups as suramin), are between three- and ten-fold less active than suramin in inhibiting IL-1 binding to EL-4.6.1 cells, and to recombinant soluble IL-1 receptor. Furthermore, in a dose-dependent manner suramin prevents several IL-1 mediated biological responses, including thymocyte proliferation, PGE-2 synthesis and IL-6 production. The inhibitory effect of the drug can be significantly reversed by the addition of excess cytokine. Taken together, the results indicate that suramin is a competitive IL-1 receptor antagonist. Because IL-1 participates in a broad range of immunological and inflammatory functions, the data suggest that suramin administration may influence important activities beyond those associated strictly with tumor inhibition.

Suramin inhibits binding of the V3 region of HIV-1 envelope glycoprotein gp120 to galactosylceramide, the receptor for HIV-1 gp120 on human colon epithelial cells

The infection of human colonic epithelial cells HT-29 by human immunodeficiency virus type 1 (HIV-1) occurs independently of CD4, the main HIV-1 receptor expressed on lymphocytes and macrophages. Recent studies from our group have shown that HT-29 cells express the glycosphingolipid galactosylceramide (GalCer), a potential alternative receptor for the HIV-1 envelope glycoprotein gp120. The binding of recombinant gp120 to GalCer was blocked by monoclonal antibodies directed against the third variable region (V3) of gp120, suggesting that the V3 domain was implicated in GalCer recognition. In the present report, we show that suramin, a polysulfonyl naphtylurea known to inhibit retroviral reverse transcriptases in vitro, blocks HIV-1 infection in HT-29 cells. The effect is dose dependent, with a half-maximal inhibition (IC50) achieved for a suramin concentration of 54 micrograms/ml. Since [3H]suramin was not significantly internalized into HT-29 cells during our infection assay (i.e. 2 h), we have considered the possibility that the drug could act at an extracellular step of the HIV-1 cycle. Using a high performance thin layer chromatography binding assay, we show that suramin inhibits binding of HIV-1 gp120 to purified GalCer with an IC50 of 25 micrograms/ml. Suramin does not bind to GalCer, since preincubation of GalCer with suramin did not prevent the subsequent attachment of gp120. Using a solid-phase assay, we show that [3H]suramin specifically binds to recombinant gp120 and that this binding could be blocked by a monoclonal antibody specific for the conserved GPGRAF motif of the V3 domain of gp120. We also demonstrate that [3H]suramin binds to multibranched synthetic GPGRAF peptides that block HIV-1 infection in HT-29 cells. Binding of [3H]suramin to V3 peptides is specific and inhibited by unlabeled suramin (IC50 of 28 micrograms/ml). In contrast, the suramin derivative NF036, that is unable to block HIV-1 infection in HT-29 cells, does not inhibit the binding of [3H]suramin to V3 peptides. Taken together, these results suggest that suramin blocks HIV-1 infection in HT-29 cells because it binds to the V3 domain of gp120 and hence prevents the interaction between gp120 and the GalCer receptor.

Novel competitive antagonists for P2 purinoceptors

Binding of the radioligand [35S]adenosine 5'-O-(2-thiodiphosphate) (ADP beta 35S) to P2 gamma purinoceptors on turkey erythrocyte membranes was used to determine the affinity of suramin and various suramin congeners belonging to different structure classes (large urea, small urea, dibenzamides and benzamides) for these receptors. Suramin was shown to be a competitive antagonist with a Ki value of 7.3 +/- 2.2 microM. The simple benzamide compound XAMR0721 (8-(3,5-dinitrophenylene carbonylimino)-1,3,5-naphthalene trisulfonate, trisodium salt) displays a high affinity for the P2 gamma purinoceptor (Ki value of 19 +/- 6 microM). Similar to suramin, compound XAMR0721 is a competitive antagonist at P2 gamma purinoceptors. In contrast to suramin, which is a potent inhibitor of the ecto-nucleotidase activity in human blood cells (44 +/- 2% residual activity at 100 microM), compound XAMR0721 is hardly active in this assay (93 +/- 1% residual activity at 100 microM). So XAMR0721, the first competitive antagonist for P2 purinoceptors that is able to discriminate between P2 purinoceptor affinity and ecto-nucleotidase activity, is an interesting pharmacological tool for the characterization of P2 purinoceptor mediated effects.

Polymerase chain reaction-based detection of dermatophyte DNA with a fungus-specific primer system

There is significant clinical interest in primers which are specific for fungi and do not hybridize to DNA of other eukaryotes or prokaryotes. Such primers would allow specific amplification of fungal DNA from human tissue samples containing fungi. Fungal identification to the species level could follow by direct sequencing or restriction analysis. Several previously described primer systems cross-react with DNA of plants and animals. We have designed a primer system that amplifies a fragment of the gene coding for the small ribosomal subunit 18S rRNA. Database searches and sequence analyses were performed using the HUSAR (Heidelberg Unix Sequence Analysis Resources) computer system at the German Cancer Research Centre, Heidelberg, Germany. Primers TR1 (5'-GTTTCTAGGACCGCCGTA) and TR2 (5'-CTCAAACTTCCATCGACTTG) bind to sequences which are homologous within the fungi, but differ from corresponding DNA fragments of plants and animals. The amplified fragment is 581 base pairs in length and contains variable, and therefore species-specific, regions. The DNA of Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton verrucosum, Trichophyton terrestre, Microsporum canis, Microsporum gypseum and Epidermophyton floccosum and of several yeast species was amplified by the primers, but not the DNA from 42 normal human skin samples. Furthermore, other DNA preparations from plants and animals, including those from radish, cabbage, wheat and mouse, did not show amplification reactions.

Chemical modifications of aminonaphthalenesulfonic acid derivatives increase effectivity and specificity of reverse transcriptase inhibition and change mode of action of reverse transcriptase and DNA polymerase alpha inhibition

The reverse transcriptase (RT) inhibition and the specificity of 15 aminonaphthalenesulfonic acid derivatives were examined with RT of a simian immunodeficiency virus derived from an African green monkey (SIVagmTYO-7). The two compounds with the strongest RT inhibition (NF415) or the highest specificity (NF345), together with suramin, were evaluated against polymerase alpha-primase complex from calf thymus. We have also compared the kinetics of inhibition of the viral and the cellular polymerase by these three compounds. While RT inhibition followed a mixed competitive and non-competitive mechanism, inhibition of the DNA polymerase alpha was competitive for suramin and non-competitive for NF415 and NF345. Certain structural characteristics appeared to be common for specific RT inhibitors.

Hepatobiliary elimination of temafloxacin

The biliary excretion of temafloxacin and temafloxacin glucuronide was characterised in this study after administration of a single oral temafloxacin 600mg dose to 8 patients with T-tube drainage of the common bile duct inserted after cholecystectomy or choledochotomy. High performance liquid chromatographic analyses of plasma, urine and bile samples collected during the 72h after temafloxacin administration showed that biliary concentrations of unchanged temafloxacin followed a time-course parallel to plasma concentrations but were 5- to 10-fold higher. Biliary temafloxacin peak concentrations ranged from 18.74 to 64.35 mg/L and time to peak concentrations from 0.71 to 10.23h. Mean hepatobiliary clearance of temafloxacin was 3.10 ml/min (0.19 L/h) when calculated for the unchanged drug and 1.43 ml/min (0.09 L/h) when calculated for its biliary excretion as glucuronic acid conjugates. Patients with higher bile production had markedly higher clearance of both temafloxacin and temafloxacin glucuronide. The elimination time-course of the conjugate in bile generally paralleled those of temafloxacin in bile and plasma, although there was a lag in the rate of appearance of the conjugate in bile. Biliary excretion of unchanged temafloxacin and temafloxacin glucuronide accounted for approximately 2.2 and 1% of the administered dose, respectively. Thus, it appears that hepatobiliary elimination of temafloxacin and its glucuronide acid accounts for only a small fraction of total temafloxacin clearance. Nonetheless, concentrations attained in the bile are far above the minimum inhibitory concentration values of pathogens relevant in biliary tract infections.