The role of dispersion type metalπ interaction in the enantiotropic phase transition of two polymorphs of tris-(thienyl)bismuthine.

Two polymorphs of tris(thienyl)bismuthine Bi(2-C4H3S)3 (1) were isolated upon crystallization from n-hexane at different temperatures. The high temperature form 1-HT crystallized at 269 K in the trigonal space group R3[combining macron], whereas the low temperature form 1-LT crystallized at 245 K in the triclinic space group P1[combining macron]. An enantiotropic phase transition was observed at 250 K showing a transition energy of 1.4 kJ mol-1. Both polymorphs reveal the formation of centrosymmetric dimers that are based on London dispersion type bismuthπ heteroarene interactions. These primary building units show additional dispersion type interactions between neighbouring dimers and as a result 2D networks are formed. DFT calculations on the model systems BiX3π thiophene (X = Cl, Me) verify the hypothesis of a soft and shallow binding potential of the London dispersion type bismuthπ heteroarene interaction, providing an explanation for the reversibility of the phase transition.

Heteroaryl bismuthines: a novel synthetic concept and metalπ heteroarene interactions.

The alkoxide Bi[OCMe2(2-C4H3S)]3 (1) is formed by the reaction of three equiv. of the alcohol HOCMe2(2-C4H3S) with Bi(OtBu)3 and subsequent hydrolysis provides the bismuth oxido cluster [Bi4O2{OCMe2(2-C4H3S)}8] (2). In contrast, the reaction of Bi(OtBu)3 and Bi[N(SiMe3)2]3 with the silanols HOSiMe2(2-C4H3X) (X = O, S, Se, and NMe), HOSiMe2(2-C4H2S-5-SiMe3) and HOSiMe2(3-C4H3S) leads to the formation of tris(heteroaryl)bismuthines Bi(2-C4H2X-5-R)3 [where X = O, R = H (3); X = S, R = H (4); X = S, R = SiMe3 (5); X = NMe, R = H (6); X = Se, R = H (7)] and Bi(3-C4H3S)3 (8). For the silanols, bismuth-carbon bond formation is observed rather than silanol-alcoholate or silanol-amide exchange. The structures of compounds 1, 2, and 4-7a in the solid state were established by single crystal X-ray diffraction and all compounds except 5 show London dispersion type bismuthπ heteroarene interactions. For the bismuthine Bi(2-C4H3Se)3 (7), two polymorphs were isolated depending on the conditions of crystallization. At 8 °C, polymorph I (7a) crystallizes from an n-hexane solution in the triclinic space group P1[combining macron], whereas polymorph II (7b) crystallizes at 20 °C from a CH2Cl2/n-pentane solution in the monoclinic space group P21/c. The heteroaryl bismuthines 3 and 4 exhibit 2D network structures as a result of bismuthπ heteroarene interactions, whereas for the pyrrole derivative 6 the dispersion type interactions provide separated dimers.

[Allopurinol therapy in imported dogs with leishmaniasis treated outside the endemic area]. / Allopurinol-Therapie bei importierten Hunden mit Leishmaniose ausserhalb des Endemiegebietes.

Canine leishmaniosis (CL) has become one of the most frequently diagnosed travel associated infection in dogs in Switzerland and Germany. The aim of the study was to define recommendations for treatment with allopurinol and follow-up examinations of dogs with CL in a non endemic area. 31 dogs infected with Leishmania were treated with allopurinol (10 - 15 mg/kg twice daily, per os) and the effectiveness was examined. The diagnosis had been confirmed by the detection of specific anti-Leishmania antibodies and/or Leihmania-DNA. 22 dogs had clinical signs (skin lesions, lameness or lack of fitness) and 9 dogs were asymptomatic but showed abnormal laboratory parameters. Under treatment with allopurinol the symptoms disappeared within 1 - 5 months in 20 dogs.

La leishmaniose canine est l'une des maladies «de voyage¼ les plus souvent diagnostiquées actuellement en Suisse et en Allemagne. Le but de la présente étude était d'élaborer des recommandations pratiques relatives au traitement à l'allopurinol et au suivi dans une zone non-endémique. On a observé, sur la base de 31 chiens souffrant de leishmaniose, importés et accompagnant des voyageurs, l'effet de l'allopurinol (10 ­ 15 mg/kg, 2x/jour per os), tant du point de vue clinique que de celui des paramètres de laboratoire. Le diagnostic avait été posé par la mise en évidence de l'ADN et/ou des anticorps. 22 chiens présentaient des signes cliniques (lésions cutanées, boiteries et baisse de condition) et 9 chiens étaient asymptomatiques mais montraient des modifications à l'analyse de laboratoire. Sous allopurinol, les symptômes ont disparu en 1 à 5 mois chez 20 chiens.

Gold nanoparticles generated by thermolysis of "all-in-one" gold(I) carboxylate complexes.

Consecutive synthesis methodologies for the preparation of the gold(I) carboxylates [(Ph(3)P)AuO(2)CCH(2)(OCH(2)CH(2))(n)OCH(3)] (n = 0-6) (6a-g) are reported, whereby selective mono-alkylation of diols HO(CH(2)CH(2)O)(n)H (n = 0-6), Williamson ether synthesis and metal carboxylate (Ag, Au) formation are the key steps. Single crystal X-ray diffraction studies of 6a (n = 0) and 6b (n = 1) were carried out showing that the P-Au-O unit is essentially linear. These compounds were applied in the formation of gold nanoparticles (NP) by a thermally induced decomposition process and hence the addition of any further stabilizing and reducing reagents, respectively, is not required. The ethylene glycol functionalities, providing multiple donating capabilities, are able to stabilise the encapsulated gold colloids. The dependency of concentration, generation time and ethylene glycol chain lengths on the NP size and size distribution is discussed. Characterisation of the gold colloids was performed by TEM, UV/Vis spectroscopy and electron diffraction studies revealing that Au NP are formed with a size of 3.3 (±0.6) to 6.5 (±0.9) nm in p-xylene with a sharp size distribution. Additionally, a decomposition mechanism determined by TG-MS coupling experiments of the gold(i) precursors is reported showing that 1(st) decarboxylation occurs followed by the cleavage of the Au-PPh(3) bond and finally release of ethylene glycol fragments to give Au-NP and the appropriate organics.

[Importance of PCR for the diagnostics of canine babesiosis]. / Bedeutung der PCR in der Diagnostik der caninen Babesiose.

Clinical standards to confirm babesiosis in dogs include the direct identification of the infectious agent in blood smears and serological assays for Babesia canis-specific antibodies. Here, we demonstrate in seven cases (with data on anamnesis, clinics, laboratory diagnostics, and therapeutic outcomes) that a new diagnostic procedure is required. This is the molecular-genetic identification of babesia by real time PCR allowing an unequivocal identification of the infectious agents. Indeed, all seven patients presenting severe clinical symptoms were PCR-positive, but only two of them had specific antibodies and showed babesia in their bloodstream. Six of the dogs appeared to have acquired babesiosis while travelling abroad, and one in the Swiss canton of Schaffhausen.

Bioavailability investigation of two different oral formulations of doxepin.

Two different oral doxepin (CAS 1668-195) formulations (Doxepin-ratiopharm 25 mg film-coated tablets as test preparation and 25 mg dragées of the reference preparation) were investigated in 30 healthy male and female volunteers in order to prove bioequivalence between these preparations. A single 75 mg oral dose (3 units of test or reference preparation) was given according to a randomised two-way cross-over design in the fasted state. Blood samples for determination of plasma concentration of doxepin and its metabolite N-desmethyldoxepin were collected at pre-defined time points up to 168 h following drug administration. A wash-out period of three weeks separated both treatment periods. Doxepin and N-desmethyldoxepin plasma concentrations were determined by means of a validated LC-MS/MS method. Values of 193,463 pgh/ml (test preparation) and 197,988 pg h/ml (reference preparation) for doxepin as well as values of 313,298 pg h/ml (test preparation) and 306,663 pgh/ml (reference preparation) for N-desmethyldoxepin for the parameter AUC0-infinity demonstrate a nearly identical extent of drug absorption. Maximum concentrations (Cmax) for doxepin/N-desmethyldoxepin of 15,960.06/6,883.69 pg/ml and 18,614.73/6,846.62 pg/ml were achieved for test and reference preparation. Time to reach doxepin maximum plasma concentration (tmax) was 1.98 h for both preparations and for N-desmethyldoxepin tmax was 4.52 h (test preparation) and 4.15 h (reference preparation). Cmax and AUC0-infinity values were tested for statistically significant differences by means of the Two One-Sided T-Tests procedure following ln-transformation of data. Bioequivalence was assumed if the 90% confidence intervals of the T/R-ratios were in the range of 80%-125% for ln-transformed AUC0-infinity and 70%-143% for ln-transformed Cmax. Based on the results obtained in this study, bioequivalence between the test and the reference preparation was demonstrated.

Detection and molecular typing of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and in different patient samples from southwest Germany.

The prevalence of different genospecies of Borrelia burgdorferi sensu lato in infected ticks could be a determinant for the risk of acquiring Lyme borreliosis (LB) and its clinical presentation. A total of 7373 ticks and 2761 samples from LB patients from the same area in southwest Germany were analyzed by PCR to assess the frequency of the occurrence of LB-associated genospecies. Fifteen percent of the tick samples and 19% of the human samples were found positive for the presence of B. burgdorferi sensu lato. Further identification of 1106 B. burgdorferi sensu lato positive tick samples by reverse line blotting and 125 positive patient samples by nested PCR using species-specific primers revealed the occurrence of B. afzelii, B. burgdorferi sensu stricto, B. garinii and B. valaisiana. Both single-species and mixed infections were noted and a similar distribution of the different genospecies was found in ticks compared with human samples. It was also the purpose of this study to obtain more information about a possible correlation between the distribution of Borrelia species and clinical syndromes of LB. Skin biopsies of 59 patients with acrodermatitis chronica atrophicans and cerebrospinal fluid samples from 78 patients with possible neuroborreliosis were analyzed. In conclusion, the distribution of the different genospecies in ticks is the decisive factor for the occurrence of the different Borrelia genospecies in samples from LB patients. Borrelia afzelii is the predominant genospecies in all kind of samples from the observed area and there seems to be no association of particular Borrelia genospecies with distinct clinical manifestations of LB.

Bioavailability investigation of two different oral formulations of Tetrazepam.

Two different oral tetrazepam (CAS 10379-14-3) formulations (Tetrazepam-ratiopharm film-coated tablets as test preparation and tablets of a reference preparation marketed in France) were investigated in 20 healthy volunteers in order to prove bioequivalence between these preparations. A single 50 mg oral dose was given according to a randomised two-way crossover design in the fasted state. Blood samples for determination of tetrazepam plasma concentrations were collected at pre-defined time points up to 96 h following drug administration. A washout period of 14 days separated both treatment periods. Tetrazepam plasma concentrations were determined by means of a validated LC-MS/MS method. Values of 3873.08 ngh/ml (test preparation) and 3930.69 ngh/ml (reference preparation) for the parameter AUC0-infinity demonstrate an nearly identical extent of drug absorption. Maximum concentrations (Cmax) of 482.08 ng/ml and 465.14 ng/ml were achieved for test and reference preparation. Time to reach maximum plasma concentration (tmax) was 1.39 hours for both preparations. Cmax and AUC0-infinity-values were tested parametrically by an analysis of variance (ANOVA). Bioequivalence was concluded if the 90% confidence intervals of the T/R-ratios were in the range of 80%-125% for AUC0-infinity and 70%-143% for Cmax. Based on the results obtained in this study, bioequivalence between the test and the reference preparation was demonstrated.

Bioavailability investigation of two different oral formulations of methylprednisolone.

Two different oral methylprednisolone (CAS 83-43-2) formulations (Methylprednisolon-ratiopharm 8 mg tables as test preparation (T) and tablets of a reference preparation (R)) were investigated in 16 healthy volunteers in order to prove bioequivalence between these preparations. A single 8 mg oral dose was given according to a randomised two-way crossover design in the fasted state. Blood samples for determination of methylprednisolone plasma concentrations were collected at pre-defined time points up to 16 h following drug administration. A washout period of 3 days separated both treatment periods. Methylprednisolone plasma concentrations were determined by means of a validated HPLC method. Values of 342.53 ng.h/ml (test preparation) and 336.61 ng.h/ml (reference preparation) for the parameter AUC0-infinity demonstrate an nearly identical extent of drug absorption. Maximum concentrations (Cmax) of 66.58 ng/ml and 70.51 ng/ml were achieved for test and reference preparation. Time to reach maximum plasma concentration (tmax) was 2.2 h for both preparations. Cmax and AUC0-infinity-values were tested parametrically by the two one-sided t-test procedure. Bioequivalence was concluded if the 90% confidence intervals of the T/R-ratios were in the range of 80-125% for AUC0-infinity and 70-143% for Cmax. Based on the results obtained in this study, bioequivalence between Methylprednisolone ratiopharm and the reference preparation was demonstrated.

Inactivation of calcineurin by hydrogen peroxide and phenylarsine oxide. Evidence for a dithiol-disulfide equilibrium and implications for redox regulation.

Calcineurin (CaN) is a Ca2+-and calmodulin (CaM)-dependent serine/threonine phosphatase containing a dinuclear Fe-Zn center in the active site. Recent studies have indicated that CaN is a possible candidate for redox regulation. The inactivation of bovine brain CaN and of the catalytic CaN A-subunit from Dictyostelium by the vicinal dithiol reagents phenylarsine oxide (PAO) and melarsen oxide (MEL) and by H2O2 was investigated. PAO and MEL inhibited CaN with an IC50 of 3-8 microM and the inactivation was reversed by 2, 3-dimercapto-1-propane sulfonic acid. The treatment of isolated CaN with hydrogen peroxide resulted in a concentration-dependent inactivation. Analysis of the free thiol content performed on the H2O2 inactivated enzyme demonstrated that only two or three of the 14 Cys residues in CaN are modified. The inactivation of CaN by H2O2 could be reversed with 1,4-dithiothreitol and with the dithiol oxidoreductase thioredoxin. We propose that a bridging of two closely spaced Cys residues in the catalytic CaN A-subunit by PAO/MEL or the oxidative formation of a disulfide bridge by H2O2 involving the same Cys residues causes the inactivation. Our data implicate a possible involvement of thioredoxin in the redox control of CaN activity under physiological conditions. The low temperature EPR spectrum of the native enzyme was consistent with a Fe3+-Zn2+ dinuclear centre. Upon H2O2-mediated inactivation of the enzyme no significant changes in the EPR spectrum were observed ruling out that Fe2+ is present in the active enzyme and that the dinuclear metal centre is the target for the oxidative inactivation of CaN.