Suppressive effect of cyclosporin A on the development of Leishmania tropica-induced lesions in genetically susceptible BALB/c mice

The effect of cyclosporin A (CyA) application on the development of cutaneous lesions was analyzed in genetically susceptible BALB/c mice infected s.c. with Leishmania tropica promastigotes. Daily i.p. injections of CyA, beginning 2 days before or at the day of the infection, dose dependently inhibited the development of parasite-induced lesions; no effect on the lesions was observed, however, if CyA application was started 14 days after the infection. Cessation of CyA administration after having successfully suppressed the cutaneous lesions for a period of 42 days, resulted in the development of lesions within 3 days. CyA had no inhibitory effect on lesions developing in L. tropica infected hypothymic BALB/c nu/nu mice. CyA or CyA-containing mouse serum did not directly affect the viability and the growth rate of L. tropica promastigotes, suggesting that the effect of the agent was imposed on the cells participating in the formation of the cutaneous lesions. Quantitative analysis of the cell distribution in the spleens of infected mice revealed that CyA markedly suppressed the infection-associated numerical increase of splenocytes. Within the Thy-1+ lymphocyte compartment, CyA had its most pronounced effect on the Lyt-1+ T lymphocyte subset. Early in the disease, the frequency of splenic cells proliferating in response to L. tropica antigen in vitro was clearly inhibited by CyA; in the later stages of the infection, however, this effect could not be observed, indicating the presence of L. tropica-inducible T cells being relatively resistant to CyA. Taken together, our findings indicate that CyA reversibly inhibits or delays the parasite-induced expansion of Lyt-1+ splenic T lymphocytes, and thus suppresses the biological function of those T cells that are instrumental for the formation of cutaneous lesions in L. tropica-infected BALB/c mice.     

Yeast regulatory gene PPR1. II. Chromosomal localization, meiotic map, suppressibility, dominance/recessivity and dosage effect

The Saccharomyces cerevisiae gene PPR1 encodes a positive regulator of the expression of the two unlinked structural genes URA1 and URA3. The gene has been mapped to a position 6.5 cM from the centromere of chromosome XII. Uninducible alleles have been selected and used to establish a meiotic map. Suppressible alleles have been identified. The sequencing of a suppressible allele confirms the nonsense nature of the mutation as well as the reading frame deduced from the nucleotide sequence. No evidence of intracistronic complementation was found, and enzymatic analysis of leaky mutants did not reveal any mutations dissociating regulation of URA1 from that of URA3. Three in vitro-constructed deletions of PPR1 have been integrated at the chromosomal locus, giving strains with a completely negative phenotype. These deletion mutants display the wild-type basal level of URA1 and URA3 expression and show a semi-dominant phenotype in heteroallelic ppr1+/ppr1-delta diploids. Amplifying PPR1 by introduction into yeast on a multicopy vector increases the induction factor of URA1 and URA3 expression. These results show that the extent of regulation of the two structural genes is dependent on the concentration of the active PPR1 protein.     

Promoters of Escherichia coli: a hierarchy of in vivo strength indicates alternate structures.

The strength in vivo of 14 promoters was determined in a system which permits the quantitation of RNA synthesis with high accuracy. Up to 75-fold differences in promoter strength were measured and the most efficient signals are promoters from coliphages T7 and T5. Their activity approaches the strength of fully induced promoters of the rRNA operons which may be close to the functional optimum of a single sequence. By contrast, a synthetic 'consensus promoter' belongs to the less efficient signals. Our data show that optimal promoter function can be achieved by alternate structures and strongly suggest that information outside of the 'classical' promoter region contributes to promoter activity.     

Selection and biochemical studies of pyrimidine-requiring mutants of Lactobacillus plantarum

Mutagenesis and mutant enrichment in Lactobacillus plantarum, a lactic acid bacterium used in silage, sauerkraut and sausage fabrication, were studied. In optimal conditions, auxotrophic mutants were obtained that permitted investigation of the de novo pyrimidine biosynthesis. Uracil-requiring mutants were characterized for their enzymatic defect, in aspartate transcarbamylase (ATCase), dihydro-orotase (DHOase), dihydro-orotate dehydrogenase (DHOdehase), orotidine monophosphate pyrophosphorylase (OMPppase) or in orotidine monophosphate decarboxylase (OMPdecase). The five enzymatic activities are totally repressed by uracil in the growth medium.     

The biotransformation of α-(2, 4, 6-trimethylphenyl) ethylamine by rabbit liver preparations

Microsomal incubation of the parent amine, α-(2, 4, 6-trimethylphenyl) ethylamine, VI, produced imine, II, alcohol, IV, oxime, V, and several unknowns. The isolation of imine, II, produces evidence that imines may be involved in the microsomal deamination of primary amines. Separate incubations of the imine, II, produced oxime, V, and several unknowns, one of which is tentatively identified as the nitro derivative. Incubation of the oxime, V, gave the alcohol, IV, the “nitro” metabolite as above and 2 unknowns. Incubation of the hydroxylamine, VII, gave oxime, V, alcohol, IV, 2 unknowns and the “nitro” metabolite.     

Vererbung erzwungener Farbveränderungen

Ohne Zusammenfassung     

Synthesis and Evaluation of Biphenyl Compounds as Kinesin Spindle Protein Inhibitors

Kinesin spindle protein (KSP), an ATP‐dependent motor protein, plays an essential role in bipolar spindle formation during the mitotic phase (M phase) of the normal cell cycle. KSP has emerged as a novel target for antimitotic anticancer drug development. In this work, we synthesized a range of new biphenyl compounds and investigated their properties in vitro as potential antimitotic agents targeting KSP expression. Antiproliferation (MTT (=3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide)) assays, combined with fluorescence‐assisted cell sorting (FACS) and Western blot studies analyzing cell‐cycle arrest confirmed the mechanism and potency of these biphenyl compounds in a range of human cancer cell lines. Structural variants revealed that functionalization of biphenyl compounds with bulky aliphatic or aromatic groups led to a loss of activity. However, replacement of the urea group with a thiourea led to an increase in antiproliferative activity in selected cell lines. Further studies using confocal fluorescence microscopy confirmed that the most potent biphenyl derivative identified thus far, compound 7 , exerts its pharmacologic effect specifically in the M phase and induces monoaster formation. These studies confirm that chemical scope remains for improving the potency and treatment efficacy of antimitotic KSP inhibition in this class of biphenyl compounds.