S1P receptor mediated activity of FTY720 phosphate mimics

Various carboxylic acids, phosphonic acids, sulfonic acids, tetrazoles as well as sulfonylhydantoins were prepared as phosphate mimics of the chiral aminophosphate 1-P to act as agonists on the S1P₁ receptor. It was found that amino phosphonates and amino carboxylates are potent S1P₁ binders. β-Amino acid 11 could be shown to reversibly reduce blood lymphocyte counts in rats after po administration.     

The effect of relaxed functional constraints on the photosynthetic gene rbcL in photosynthetic and nonphotosynthetic parasitic plants

The photosynthetic gene rbcL has been lost or dramatically altered in some lineages of nonphotosynthetic parasitic plants, but the dynamics of these events following loss of photosynthesis and whether rbcL has sustained functionally significant changes in photosynthetic parasitic plants are unknown. To assess the changes to rbcL associated with the loss of functional constraints for photosynthesis, nucleotide sequences from nonparasitic and parasitic plants of Scrophulariales were used for phylogeny reconstruction and character analysis. Plants in this group display a broad range of parasitic abilities, from photosynthetic ("hemiparasites") to nonphotosynthetic ("holoparasites"). With the exception of Conopholis (Orobanchaceae), the rbcL locus is present in all parasitic plants of Scrophulariales examined. Several holoparasitic genera included in this study, including Boschniakia, Epifagus, Orobanche, and Hyobanche, have rbcL pseudogenes. However, the holoparasites Alectra orobanchoides, Harveya capensis, Harveya purpurea, Lathraea clandestina, Orobanche corymbosa, O. fasciculata, and Striga gesnerioides have intact open reading frames (ORFs) for the rbcL gene. Phylogenetic hypotheses based on rbcL are largely in agreement with those based on sequences of the nonphotosynthetic genes rps2 and matK and show a single origin of parasitism, and loss of photosynthesis and pseudogene formation have been independently derived several times in Scrophulariales. The mutations in rbcL in nonparasitic and hemiparasitic plants would result in largely conservative amino acid substitutions, supporting the hypothesis that functional proteins can experience only a limited range of changes, even in minimally photosynthetic plants. In contrast, ORFs in some holoparasites had many previously unobserved missense substitutions at functionally important amino acid residues, suggesting that rbcL genes in these plants have evolved under relaxed or altered functional constraints.      

Alternative splicing and protein function

Background  

Alternative splicing is a major mechanism of generating protein diversity in higher eukaryotes. Although at least half, and probably more, of mammalian genes are alternatively spliced, it was not clear, whether the frequency of alternative splicing is the same in different functional categories. The problem is obscured by uneven coverage of genes by ESTs and a large number of artifacts in the EST data.     

Allogeneic dendritic cell vaccination against metastatic renal cell carcinoma with or without cyclophosphamide

In this phase I/II study, we evaluated the feasibility, safety and efficacy of allogeneic dendritic cells (DCs) with or without cyclophosphamide in the treatment of patients with metastatic renal cell carcinoma (RCC). Immunomagnetic beads were used to isolate CD14⁺ monocytes from healthy donor leukapheresis products, and CD83⁺ antigen-pulsed monocyte-derived DCs (moDCs) loaded with tumor lysate and keyhole limpet hemocyanin (KLH) were generated. Twelve patients were treated with allogeneic moDCs alone, while ten patients also received cyclophosphamide on days 4 and 3 prior to vaccination. Of the 22 patients enrolled, 20 received full treatment consisting of at least three vaccinations at monthly intervals. Two mixed responses with substantial tumor regression were observed. In 3 patients, disease stabilization occurred, in 13 patients disease progressed and 4 patients were lost to follow-up. Overall, immune responses against KLH and tumor lysate were weak or absent; however, the strongest increases in antigen-independent and KLH-specific responses were observed in the 2 patients with mixed responses. In addition, 1 of them showed a substantial increase in oncofetal antigen (OFA)-specific IFN- production. Importantly, the 2 mixed responders and 1 patient with stable disease belonged to the cyclophosphamide group. Median overall survival in the cyclophosphamide group was 23.2 and 20.3 months in the group that received allogeneic moDCs alone. Allogeneic immunotherapy with moDCs is feasible and well tolerated. However, the immunogenicity of allogeneic moDCs is clearly less pronounced than that of autologous moDC immunotherapy. Cyclophosphamide may have the capacity to augment DC-induced antitumor immunity.     

Computer simulation of the motoneuron pool–muscle complex. I. Input system and motoneuron pool

 The aim of the present study was to simulate the input system and the motoneuron (MN) pool of the MN pool–muscle complex (MNPMC). Input fibers, which can originate from command centers in the central nervous system or from sensory organs, activate the MN pool. They generate sequences of action potentials, the frequency of which is proportional to a time-dependent activation factor (which is an input to the model). Different connection patterns between the input fibers and motor units (MUs) are allowed. For simplicity and since no precise experimental data are available, 70 input fibers and 4 boutons per fiber and MN are simulated (this corresponds approximately to the monosynaptic group-Ia input of the cat medial gastrocnemius muscle). Each bouton generates the same conductance change in the postsynaptic membrane. The MNs are modeled with a single compartment and a homogenous membrane. According to experimental data, the membrane leakage conductance and capacitance are MU dependent. Since the precise relation is unknown: (a) the computed relation between MU contraction force and the MN leakage conductance was taken from a steady-state MNPMC model, and (b) the capacitance was assumed to be proportional to the leakage conductance. The MN membrane includes time- and voltage-dependent ionic channels (fast and slow K⁺ and low- and high-threshold Ca²⁺ channels). The density and time constant of the slow K⁺ channels and the density of the Ca²⁺ channels were fitted to approximate afterhyperpolarization characteristics and frequency-injected current relations of type-identified cat MNs. If the membrane reaches a voltage threshold the MNs generate action potentials, which were simulated by voltage pulses. The activation of the MN pool of the human first dorsal interosseus muscle was simulated with injected and synaptic currents in order to illustrate the size principle, synaptic noise, and other features of muscle activation. It is concluded that the present model reproduces the main properties of the input–output relations of different MN types within a muscle. Together with the simulation of the muscle force and the surface EMG, which will be published in subsequent papers, it will be a powerful tool for reproducing experiments on the motor system and investigating functional mechanisms of motor control. Received: 17 April 2001 / Accepted in revised form: 6 November 2001     

Inhibitors of vitamin D hydroxylases: structure-activity relationships

Aiming at new drugs to efficiently treat diseases, in which either increased or decreased levels of active vitamin D are desirable, we have designed some 400 structurally different azole-type inhibitors and examined their capacity to selectively block vitamin D metabolism by CYP24 or synthesis by CYP27B, in human keratinocytes. Based on resulting data, we built pharmacophore models of the active sites using commercial software. The overlay of potent selective compounds indicated similar docking modes in the two-substrate pockets and allowed for identification of bioactive conformations. Superimposing these bioactive conformations with low energy conformers of 25(OH)D(3) suggested that the substrate-mimicked by strong inhibitors in size, shape and lipophilic character-binds to both enzymes in 6s-trans configuration. Pharmacophoric models implied a similar geometry of the substrate sites, nevertheless specific features of CYP24 and CYP27B could be defined. Bulky substituents in alpha-position to the azole caused selectivity for CYP24, whereas bulky substituents in beta-position could result in selectivity for CYP27B. Moreover, studies with small sterically restricted inhibitors revealed a probable location of the 3-OH-group of 25(OH)D(3) in CYP27B. In the absence of crystal structures, our inhibitors are valuable tools to model and understand the active sites of vitamin D hydroxylases, resulting in the design of powerful, selective therapeutics.     

6-[2-(adamantylidene)-hydroxybenzoxazole]-O-sulfamate, a steroid sulfatase inhibitor for the treatment of androgen- and estrogen-dependent diseases

Steroid sulfatase (STS) offers a new target for the treatment of steroid hormone-dependent diseases, such as breast and prostate cancer and androgen-dependent skin diseases. We here characterize a novel non-estrogenic inhibitor of the enzyme, namely 6-[2-(adamantylidene)-hydroxybenzoxazole]-O-sulfamate (AHBS), with special attention to its potential use in the treatment of acne. The compound blocks STS activity in homogenates of human skin with IC(50)=16 nM. Following a single oral dose (5 mg/kg) in rats, the compound blocks STS in the skin by 95% at 8 h, followed by recovery of activity over 5 days. Following topical application to the skin, both in vitro and in vivo, AHBS passes through the stratum corneum leading to inhibition of STS activity in the dermal compartment with rapid onset and long duration. Topical application of AHBS to G?ttingen minipigs for a period of 2 weeks does not induce symptoms of ichthyosis as seen in STS-deficient human subjects, but leads to a reduction of sebum secretion to the skin surface. Based on these data, clinical studies with AHBS in acne patients are warranted, in order to verify the hypothesis on the importance of the sulfatase pathway in androgen-dependent skin diseases.     

Comparison of tetrachromic VOF stain to other histochemical staining techniques for characterizing stromal soft and hard tissue components

The components of hard tissues including dentin, enamel, cementum, bone and other calcified deposits, and mature and immature collagen pose problems for identification in routine hematoxylin and eosin (H & E) stained sections. Use of combinations of stains can demonstrate the components of hard tissues and soft tissues distinctly. We assessed the efficacy of the Verde Luz-orange G-acid fuchsin (VOF) stain for differentiating hard and soft connective tissues and compared results with other histochemical staining techniques. Eighty tissue sections comprising developing tooth (30), ossifying fibroma (30) and miscellaneous pathologies (20) expected to contain varying types of calcified tissues were stained with H & E, VOF, and Masson's trichrome (MT). In developing tooth, VOF demonstrated better differentiation of hard tissues, while it was comparable to MT for ossifying fibroma and miscellaneous pathologies. The intensity of staining was greater with VOF than with the other stains studied. VOF stains hard tissue components distinctly and gives good contrast with the surrounding connective tissue. VOF is comparable to MT, but has added advantages including single step staining, rapid and easy procedures, and it distinguishes the maturity of the tissues.     

Interactions of neural glycosaminoglycans and proteoglycans with protein ligands: assessment of selectivity, heterogeneity and the participation of core proteins in binding

The method of affinity coelectrophoresis was used to study the binding of nine representative glycosaminoglycan (GAG)-binding proteins, all thought to play roles in nervous system development, to GAGs and proteoglycans isolated from developing rat brain. Binding to heparin and non-neural heparan and chondroitin sulfates was also measured. All nine proteins-laminin-1, fibronectin, thrombospondin-1, NCAM, L1, protease nexin-1, urokinase plasminogen activator, thrombin, and fibroblast growth factor-2-bound brain heparan sulfate less strongly than heparin, but the degree of difference in affinity varied considerably. Protease nexin-1 bound brain heparan sulfate only 1.8- fold less tightly than heparin (Kdvalues of 35 vs. 20 nM, respectively), whereas NCAM and L1 bound heparin well (Kd approximately 140 nM) but failed to bind detectably to brain heparan sulfate (Kd>3 microM). Four proteins bound brain chondroitin sulfate, with affinities equal to or a few fold stronger than the same proteins displayed toward cartilage chondroitin sulfate. Overall, the highest affinities were observed with intact heparan sulfate proteoglycans: laminin-1's affinities for the proteoglycans cerebroglycan (glypican-2), glypican-1 and syndecan-3 were 300- to 1800-fold stronger than its affinity for brain heparan sulfate. In contrast, the affinities of fibroblast growth factor-2 for cerebroglycan and for brain heparan sulfate were similar. Interestingly, partial proteolysis of cerebroglycan resulted in a >400- fold loss of laminin affinity. These data support the views that (1) GAG-binding proteins can be differentially sensitive to variations in GAG structure, and (2) core proteins can have dramatic, ligand-specific influences on protein-proteoglycan interactions.