Research of spectral and luminescent properties of humic acids of various genesis

The spectral-luminescent properties isolated by means of aqueous-alkaline extraction humic acids of various origin have been studied. A comparative analysis of humic acids obtained from brown coal with "Fluka" humic acids standard sample was carried out. It is shown that the obtained samples of humic acids have their own unique properties and differences due to the complexity of their structure

Structure of human cyclophilin A in complex with the novel immunosuppressant sanglifehrin A at 1.6 A resolution.

Sanglifehrin A (SFA) is a novel immunosuppressant isolated from Streptomyces sp. that binds strongly to the human immunophilin cyclophilin A (CypA). SFA exerts its immunosuppressive activity through a mode of action different from that of all other known immunophilin-binding substances, namely cyclosporine A (CsA), FK506, and rapamycin. We have determined the crystal structure of human CypA in complex with SFA at 1.6 A resolution. The high resolution of the structure revealed the absolute configuration at all 17 chiral centers of SFA as well as the details of the CypA/SFA interactions. In particular, it was shown that the 22-membered macrocycle of SFA is deeply embedded in the same binding site as CsA and forms six direct hydrogen bonds with CypA. The effector domain of SFA, on the other hand, has a chemical and three-dimensional structure very different from CsA, already strongly suggesting different immunosuppressive mechanisms. Furthermore, two CypA.SFA complexes form a dimer in the crystal as well as in solution as shown by light scattering and size exclusion chromatography experiments. This observation raises the possibility that the dimer of CypA.SFA complexes is the molecular species mediating the immunosuppressive effect

<span style="font-size:12.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-ansi-language: EN-IN;mso-fareast-language:EN-IN;mso-bidi-language:AR-SA" lang="EN-IN">Synthetic modifications of ascomycin : Part III¹ - A concise transformation of <i>iso-</i>ascomycin to 19, 20-<i style="mso-bidi-font-style:normal">seco</i>-derivatives</span>

831-834<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">A short transformation of 22(R)-dihydro-iso-ascomycin to novel 19, 20-seco-iso-ascomycin derivatives is described. The biological activity of the new compounds is compared with that of standards in assays relevant for ascomycin/FK 506 type compounds <span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">(macrophilin-12 binding assay, IL-2 reporter gene assay). The results indicate that the 19, 20-seco-derivative 3 might develop into a key intermediate for the synthesis of new derivatives with interesting biological activities.</span

Indolyl-naphthyl-maleimides as potent and selective Inhibitors of Protein Kinase C-alpha/beta

The indolyl-naphthyl maleimide 7 is a potent inhibitor of the classical PKC isotypes PKC-alpha/beta and shows excellent selectivity over the novel PKC isotypes delta, epsilon, eta and theta and other kinases belonging to the AGC family. The SAR around 7 as well as the physico-chemical characteristics of selected derivatives and their activity in T and B cell activation and proliferation assays are discussed

Fingerprints of CD8+ T cells on human pre-plasma and memory B cells.

Differentiation of B cells is a stringently controlled multi-step process, which is still incompletely understood. Here we identify and characterize a rare population of human B cells, which surprisingly carry CD8AB on their surface. Existence of such cells was demonstrated both in tonsils and in human apheresis material. Gene expression profiling and real time PCR detected however no CD8A or CD8B message in these cells. Instead, we found that surface CD8 was hijacked from activated CD8+ T cells by a transfer process that required direct cell-to-cell contact. A focused transcriptome analysis at single cell level allowed the dissection of the CD8 positive B cell population. We found that the affected cells are characteristically of the CD27+CD200- phenotype, and consist of two discrete late-stage subpopulations that carry signatures of activated memory B like cells, and early plasmablasts. Thus, there is only a restricted time window in the differentiation process during which B cells can intimately interact with CD8+ T cells. The findings point to a novel link between the T and B arms of the adaptive immune system, and suggest that CD8+ T cells have the capability to directly shape the global antibody repertoire

Highly reduced binding to high and low affinity mouse Fc gamma receptors by L234A/L235A and N297A Fc mutations engineered into mouse IgG2a

The effects of the Fc silencing mutations such as Leucine (L) to Alanine (A) substitution at the position 234 and 235 (LALA) and the Alanine (A) to Asparagine (N) substitution at position 297 (N297A) are well investigated for human IgG. However, the effects of the same two silencing Fc mutations in a mouse IgG backbone are not yet well investigated in respect to binding to mouse Fc gamma receptors (FcgR) and complement and subsequent effector functions. By using a mouse IgG2a tool antibody directed against mouse OX40L, we demonstrate a highly reduced binding to high and low affinity recombinant and cell expressed mouse FcgRs, when compared to the mouse IgG2a with the wild type backbone. Reduced FcgR binding by the two investigated Fc mutants could further be confirmed on primary mouse macrophages expressing their native FcgRs, where the high affinity mouse FcgRI was identified as major Fc interaction partner. In addition, we reveal that the LALA and N297A mutations in the mIgG2 also reduced binding to C1q of human origin. Thus, here we provide experimental evidence that the two investigated Fc mutations in the mouse IgG backbone lead to similar “silencing” properties as previously demonstrated for the human IgG and thus represent a useful method to alter effector functions in tool antibodies to be used in mouse model

Strongly reduced alloreactivity and long-term survival times of cardiac allografts in Vav1- and Vav1/Vav2-knockout mice.

Vav proteins mediate T- and B-cell activation by functioning as GTP/GDP exchange factors for small GTPases. We have studied the role of Vav1 and Vav2 in allogeneic T-cell activation, antibody responses and allograft rejection. Alloantigen-induced proliferation of T cells from Vav1- and Vav1/Vav2-knockout (ko) mice was decreased by >90% in a mixed lymphocyte reaction. In whole-blood cultures, Vav deficiency led to markedly impaired T- and B-cell activation. Expansion of Vav1- or Vav1/Vav2-ko T cells (C57BL/6) was reduced after transfer into severe combined immune deficiency/beige recipient mice (BALB/c). After priming with 2,4-dinitrophenyl (DNP)-keyhole limpet hemocyanin, T-cell-dependent anti-DNP IgM and IgG antibody levels were normal in Vav1-ko mice but undetectable in Vav1/Vav2-ko mice. The median survival time of BALB/c cardiac allografts transplanted into C57BL/6 Vav1-ko mice (n = 13) or Vav1/Vav2-ko mice (n = 5) was >100 and >77 days, compared with 8-9 days in the corresponding wild-type mice. Vav1/Vav2-ko mice with <100 days graft survival developed bacterial skin infections and were prematurely killed with beating cardiac allograft. Long-term surviving transplants of single and double ko mice showed mild cellular interstitial rejection and mild to severe vascular remodeling. In conclusion, our studies show for the first time that the absence of Vav1 and Vav1/Vav2 in ko mice strongly reduces alloreactivity and results in long-term allograft survival, whereas antibody responses were only affected in Vav1/Vav2 ko mice

Pimecrolimus: absorption, distribution, metabolism, and excretion in healthy volunteers after a single oral dose and supplementary investigations in vitro.

The absorption and disposition of pimecrolimus, a calcineurin inhibitor developed for the treatment of inflammatory skin diseases, was investigated in four healthy volunteers after a single oral dose of 15 mg of [(3)H]pimecrolimus. Supplementary information was obtained from in vitro experiments. Pimecrolimus was rapidly absorbed. After t(max) (1-3 h), its blood concentrations fell quickly to 3% of C(max) at 24 h, followed by a slow terminal elimination phase (average t(1/2) 62 h). Radioactivity in blood decreased more slowly (8% of C(max) at 24 h). The tissue and blood cell distribution of pimecrolimus was high. The metabolism of pimecrolimus in vivo, which could be well reproduced in vitro (human liver microsomes), was highly complex and involved multiple oxidative O-demethylations and hydroxylations. In blood, pimecrolimus was the major radiolabeled component up to 24 h (49% of radioactivity area under the concentration-time curve(0-24) h), accompanied by a large number of minor metabolites. The average fecal excretion of radioactivity between 0 and 240 h amounted to 78% of dose and represented predominantly a complex mixture of metabolites. In urine, 0 to 240 h, only about 2.5% of the dose and no parent drug was excreted. Hence, pimecrolimus was eliminated almost exclusively by oxidative metabolism. The biotransformation of pimecrolimus was largely catalyzed by CYP3A4/5. Metabolite pools generated in vitro showed low activity in a calcineurin-dependent T-cell activation assay. Hence, metabolites do not seem to contribute significantly to the pharmacological activity of pimecrolimus