Aminothiol multidentate chelators against Chagas disease

Three compounds of an aminothiol family of iron chelators were examined for activity against trypomastigote (human) and epimastigote (vector) forms of Trypanosoma cruzi: tetraethyl and tetramethyl derivatives of ethane-1,2-bis (N-1-amino-3-ethyl butyl-3-thiol) (BAT-TE and BAT-TM) and N',N',N'-tris-(2-methyl-2-mercaptopriopyl)- 1,4,7-triazacyclonane (TAT). BAT-TE at 270 microM completely arrested the growth of trypomastigote forms in mouse blood stored at 4 degrees C for 24 h (IC(50) 67.7+/-7 microM), while BAT-TM arrested growth at 630 microM (IC(50) 158+/-17 microM) and TAT at concentrations >800 microM (IC(50) 415+/-55 microM). In T. cruzi-infected mice, BAT-TE and BAT-TM had no anti-trypanosomal activity in doses up to 200 mg/kg, whether the route of administration was intraperitoneal or oral, and TAT was not tested due to insufficient quantity. TAT had an IC(50) of 52+/-7 microM against the epimastigote forms while BAT-TM and BAT-TE were inhibitory only at concentrations >250 microM. The trypanocidal activity of BAT derivatives in blood stored at 4 degrees C makes these compounds potential candidates for the purpose of clearing donated blood of trypomastigotes.     

State of the art of the production of the antimalarial compound artemisinin in plants

For more than three centuries we have relied on the extracts of the bark of Cinchona species to treat malaria. Now, it seems we may be changing to the leaves of a Chinese weed, Artemisia annua, and its active compound artemisinin. Artemisinin-derived drugs have been proved particularly effective treatments for severe malaria, even for multi-drug-resistant malaria. However, this promising antimalarial compound remains expensive and is hardly available on a global scale. Therefore, many research groups have directed their investigations toward the enhancement of artemisinin production in A. annua cell cultures or whole plants in order to overproduce artemisinin or one of its precursors. This article provides a brief review of the state of art of the different aspects in A. annua research.     

Agrobacterium tumefaciens-mediated transformation of Artemisia annua L. and regeneration of transgenic plants

Summary A transformation system was developed for Artemisia annua L. plants. Leaf explants from in vitro grown plants developed callus and shoots on medium with 0.05 mg/L naphthaleneacetic acid and 0.5 mg/L N⁶-benzyladenine after transformation with the C58C1 Rif^R (pGV2260) (pTJK136) Agrobacterium tumefaciens strain. A concentration of 20 mg/L kanamycin was added in order to select transformed tissue. Kanamycin resistant shoots were rooted on naphthaleneacetic acid 0.1 mg/L. Polymerase chain reactions and DNA sequencing of the amplification products revealed that 75% of the regenerants contained the foreign genes. 94% of the transgenic plants showed a -glucuronidase-positive response.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - BA N⁶-benzyladenine - GM germination medium - GMVIT germination medium with vitamins - GUS -glucuronidase - Kin kinetin (N⁶-furfurylaminopurine) - NAA -naphthaleneacetic acid - NPT II neomycin phosphotransferase II - PCR Polymerase Chain Reaction - T-DNA transfer-DNA - X-glucuronide 5-bromo-4-chloro-3-indolyl -D-glucuronide     

Whole-exome sequencing identifies mutations in GPR179 leading to autosomal-recessive complete congenital stationary night blindness

Congenital stationary night blindness (CSNB) is a heterogeneous retinal disorder characterized by visual impairment under low light conditions. This disorder is due to a signal transmission defect from rod photoreceptors to adjacent bipolar cells in the retina. Two forms can be distinguished clinically, complete CSNB (cCSNB) or incomplete CSNB; the two forms are distinguished on the basis of the affected signaling pathway. Mutations in NYX, GRM6, and TRPM1, expressed in the outer plexiform layer (OPL) lead to disruption of the ON-bipolar cell response and have been seen in patients with cCSNB. Whole-exome sequencing in cCSNB patients lacking mutations in the known genes led to the identification of a homozygous missense mutation (c.1807C>T [p.His603Tyr]) in one consanguineous autosomal-recessive cCSNB family and a homozygous frameshift mutation in GPR179 (c.278delC [p.Pro93Glnfs^∗57]) in a simplex male cCSNB patient. Additional screening with Sanger sequencing of 40 patients identified three other cCSNB patients harboring additional allelic mutations in GPR179. Although, immunhistological studies revealed Gpr179 in the OPL in wild-type mouse retina, Gpr179 did not colocalize with specific ON-bipolar markers. Interestingly, Gpr179 was highly concentrated in horizontal cells and Müller cell endfeet. The involvement of these cells in cCSNB and the specific function of GPR179 remain to be elucidated.     

TRPM1 Is Mutated in Patients with Autosomal-Recessive Complete Congenital Stationary Night Blindness

Night vision requires signaling from rod photoreceptors to adjacent bipolar cells in the retina. Mutations in the genes NYX and GRM6, expressed in ON bipolar cells, lead to a disruption of the ON bipolar cell response. This dysfunction is present in patients with complete X-linked and autosomal-recessive congenital stationary night blindness (CSNB) and can be assessed by standard full-field electroretinography (ERG), showing severely reduced rod b-wave amplitude and slightly altered cone responses. Although many cases of complete CSNB (cCSNB) are caused by mutations in NYX and GRM6, in ∼60% of the patients the gene defect remains unknown. Animal models of human diseases are a good source for candidate genes, and we noted that a cCSNB phenotype present in homozygous Appaloosa horses is associated with downregulation of TRPM1. TRPM1, belonging to the family of transient receptor potential channels, is expressed in ON bipolar cells and therefore qualifies as an excellent candidate. Indeed, mutation analysis of 38 patients with CSNB identified ten unrelated cCSNB patients with 14 different mutations in this gene. The mutation spectrum comprises missense, splice-site, deletion, and nonsense mutations. We propose that the cCSNB phenotype in these patients is due to the absence of functional TRPM1 in retinal ON bipolar cells.