Molecular Target-Guided Tumor Therapy with Natural Products Derived from Traditional Chinese Medicine

A tremendous interest exists in the Western world in Traditional Chinese Medicine (TCM) with rapidly increasing export rates of TCM products from China to Europe and USA. This led to a national decision of the Chinese government to implement a "Plan for the Modernization of Chinese Medicine". Concerning the use of Chinese medicinal herbs, two major directions can be distinguished. One field is phytochemistry and pharmacognosy. Secondary metabolites isolated from Chinese plants can be easily subjected to pharmacological, molecular biological, and pharmacogenomic analyses using methods of modern cell and molecular biology as exemplified for camptothecin from Camptotheca acuminata in the present review. The second field of interest is phytomedicine. Standardized international quality guidelines help to improve quality, safety and efficacy of Chinese medicinal herbs. Sustainability of natural products from TCM can be reached by breeding high-yield varieties or by biotechnological approaches. In the long term, natural products from TCM can contribute to the development of molecular target-guided therapies and individualized treatment strategies.

Trainingsmethode für Regionalanästhesisten

INTRODUCTION

Optimized training facilities are the key to efficient teaching of regional anesthesia.

MATERIAL AND METHODS

A combination of Thiel's embalming method, flap dissection and pulse simulation was offered to participants in several workshops on regional anesthesia. Tutors, experienced anesthetists and anatomists, evaluated the workshop and compared Thiel's method to classic formaldehyde conservation. Additionally both embalming methods were assessed with regard to the mechanical properties according to the requirements of regional anesthesia.

RESULTS

The evaluation showed high acceptance of the method offered in the workshop. In a comparison of fixation methods Thiel's method was generally preferred as it presented more similar conditions to living patients and almost ideal conditions for regional anesthesia.

CONCLUSION

The presented method is an optimized, strongly accepted teaching and training tool for teaching regional anesthesia.

Improvement of the primary success rate of recanalization of chronic total coronary occlusions with the Safe-Cross system after failed conventional wire attempts

BACKGROUND

In view of the improved long-term patency with drug-eluting stents, the challenge with chronic total coronary occlusion (CTO) remains the low primary success rate. Improved guide wires have increased this rate, but alternative devices may be of additional value. The goal of the present study was to determine the additional benefit of a new penetration device in CTOs after an extensive conventional wire approach.

METHODS AND RESULTS

In 148 consecutive patients the recanalization of a CTO of >3 months was attempted. A conventional wire approach was used with recent dedicated recanalization wires, which was successful in 104 patients (70%). If after at least 20 min of fluoroscopic time no crossing of the wire was achieved, the Safe-Cross wire (SC) (Intralumina) was used which enables verification of the intraluminal wire position via optical reflectometry, and crossing of resistent occlusion caps by radiofrequency ablation. Due to severe dissections after the conventional approach, the SC was not used in 10 patients. In 34 patients the SC wire was applied, leading to successful lesion crossing in 14 patients (41%). Thus, the primary success rate was improved from 70.2% to 79.7%. No periprocedural major adverse events were observed with the SC wire. The successful attempts with the SC wire were predominantly in blunt occlusions. All patients with successful wire passage could be treated with one or more stents.

CONCLUSIONS

In a real world cohort of patients with CTO, the SC wire could increase the primary success rate after failed extensive conventional wire attempt. In these worst case patients the SC success rate was 41%. This new wire appears to have additional potential in failures of a conventional wire approach.

Model-free analysis of binding at lipid membranes employing micro-calorimetric measurements

Based on universal thermodynamic principles (Schwarz in Biophys Chem 86:119-129, 2000) it is shown how measured enthalpy changes can be utilized to determine the relevant binding isotherm as well as the variation of the molar enthalpy change. This is carried out in a novel way involving multiple titration experiments whose evaluation requires no beforehand assumptions or models whatever. An appropriate specific model mechanism may be discussed afterwards and developed in view of the given experimental results. The pertinent procedure is demonstrated using micro-calorimetric data obtained in the case of the local anesthetic dibucaine as it associates with POPC liposomes. Mutual interactions of the bound ligand molecules could be described in terms of repulsive enthalpic and entropic activity coefficients. Apparently these are induced by electrostatic forces and by the finite size of binding sites, respectively.

In vivo characterization of progestins with reduced non-genomic activity in vitro

Postmenopausal women that still have an uterus and suffer from hot flushes are treated with combinations of estrogens and progestins. Whereas estrogens are indispensable for treating postmenopausal symptoms, progestins are added to counteract the proliferative activity of estrogens on uterine epithelial cells. However, in the mammary gland, progestins, given together with estrogens, stimulate the proliferation of mammary epithelial cells. Therefore, progestins with reduced proliferative activity in the mammary gland would be of advantage for hormone therapy of postmenopausal women. In order to identify progestins with better tissue-selectivity, we exploited the activation of different signal transduction pathways by the classical progesterone receptor. We demonstrated that progestins with reduced non-genomic versus genomic activity in vitro show a better dissociation of uterine versus mammary gland effects in vivo than medroxyprogesterone acetate (MPA), a synthetic progestin that is widely used in hormone therapy.

Rapid separation of four main taxoids inTaxus species by a combined LLP-SPE-HPLC (PAD) procedure

A method is described for the simultaneous determination of paclitaxel and three related taxoids, 10-deacetylbaccatin III (10-DAB III), baccatin III, and cephalomannine, in the extracts from the needles of three Chinese yew species, Taxus cuspidata, T. chinensis, and T. media. SPE was applied as the sample preparation technique and RP-HPLC with a photodiode array detector (PAD) was used for the analysis of extract samples. The crude extracts were treated with an improved SPE cartridge packed with a combination of 1-vinyl-pyrrolidin-2-one and divinyl-benzene. The eluent was 75% methanol. The following separation was achieved with a gradient program on an HIQ SIL C18W column in a system of ACN/water within 60 min. The samples were detected by PAD at wavelengths of 232.1 nm for 10-DAB III, 229.8 nm for baccatin III and paclitaxel, and 223.9 nm for cephalomannine. The content of 10-DAB III, baccatin III, cephalomannine, and paclitaxel varied from 0.0277 to 0.0875, 0.0254 to 0.0405, 0.0715 to 0.2486, and 0.0996 to 0.1301 mg/g in fresh needles of the above yew species, respectively. The assay achieved good resolution in the separation between the four compounds, and it can be used for quality control or purity determination for those in bulk and pharmceutical dosage forms.

The Crystal Structure of Cdc42 in Complex with Collybistin II, a Gephyrin-interacting Guanine Nucleotide Exchange Factor

The synaptic localization of ion channel receptors is essential for efficient synaptic transmission and the precise regulation of diverse neuronal functions. In the central nervous system, ion channel receptors reside in the postsynaptic membrane where they are juxtaposed to presynaptic terminals. For proper function, these ion channels have to be anchored to the cytoskeleton, and in the case of the inhibitory glycine and gamma-amino-butyric acid type A (GABA(A)) receptors this interaction is mediated by a gephyrin centered scaffold. Highlighting its central role in this receptor anchoring scaffold, gephyrin interacts with a number of proteins, including the neurospecific guanine nucleotide exchange factor collybistin. Collybistin belongs to the Dbl family of guanine nucleotide exchange factors, occurs in multiple splice variants, and is specific for Cdc42, a small GTPase belonging to the Rho family. The 2.3 Angstroms resolution crystal structure of the Cdc42-collybistin II complex reveals a novel conformation of the switch I region of Cdc42. It also provides the first direct observation of structural changes in the relative orientation of the Dbl-homology domain and the pleckstrin-homology domain in the same Dbl family protein. Biochemical data indicate that gephyrin negatively regulates collybistin activity.

Spectroscopic and kinetic studies of Arabidopsis thaliana sulfite oxidase: nature of the redox-active orbital and electronic structure contributions to catalysis

Plant sulfite oxidase from Arabidopsis thaliana has been characterized both spectroscopically and kinetically. The enzyme is unusual in lacking the heme domain that is present in the otherwise highly homologous enzyme from vertebrate sources. In steady-state assays, the enzyme exhibits a pH maximum of 8.5 and is also found to function as a selenite oxidase. Sulfite at the lowest experimentally feasible concentrations reduces the enzyme within the dead-time of a stopped-flow instrument at 5 degrees C, indicating that the A. thaliana enzyme has a limiting rate constant for reduction, k(red), at least 10 times greater than that of the chicken enzyme (190 s(-1)). The EPR parameters for the high- and low-pH forms of the A. thaliana enzyme have been determined, and the g-values are found to resemble those previously reported for the vertebrate enzymes. Finally, the A. thaliana enzyme has been probed by resonance Raman spectroscopy. A detailed analysis of the vibrational spectrum in the region where Mo=O stretching modes are anticipated to occur has been performed with the help of density functional theory calculations, evaluated in the context of the Raman data. Calculated frequencies obtained for two model systems have been compared to experimental resonance Raman spectra of oxidized A. thaliana sulfite oxidase catalytically cycled in both H2(16)O and H2(18)O. The vibrational frequency shifts observed upon (18)O-labeling of the enzyme are consistent with theoretical models in which either the equatorial oxygen or both equatorial and axial atoms of the dioxomolybdenum center are labeled. Importantly, the vibrational mode description is consistent with the active site possessing geometrically inequivalent oxo ligands and a Mo d(xy) redox-active molecular orbital oriented in the equatorial plane forming a pi-bonding interaction solely with the equatorial oxo, O(eq). Electron occupancy of this Mo=O(eq) pi* redox orbital upon interaction with substrates would effectively labilize the Mo=O(eq) bond, providing the dominant contribution to lowering the activation energy for oxygen atom transfer.

Deciphering the structural framework of glycine receptor anchoring by gephyrin

Glycine is the major inhibitory neurotransmitter in the spinal cord and brain stem. Gephyrin is required to achieve a high concentration of glycine receptors (GlyRs) in the postsynaptic membrane, which is crucial for efficient glycinergic signal transduction. The interaction between gephyrin and the GlyR involves the E-domain of gephyrin and a cytoplasmic loop located between transmembrane segments three and four of the GlyR beta subunit. Here, we present crystal structures of the gephyrin E-domain with and without the GlyR beta-loop at 2.4 and 2.7 A resolutions, respectively. The GlyR beta-loop is bound in a symmetric 'key and lock' fashion to each E-domain monomer in a pocket adjacent to the dimer interface. Structure-guided mutagenesis followed by in vitro binding and in vivo colocalization assays demonstrate that a hydrophobic interaction formed by Phe 330 of gephyrin and Phe 398 and Ile 400 of the GlyR beta-loop is crucial for binding.

Molybdenum cofactor biosynthesis and molybdenum enzymes

The molybdenum cofactor (Moco) forms the active site of all eukaryotic molybdenum (Mo) enzymes. Moco consists of molybdenum covalently bound to two sulfur atoms of a unique tricyclic pterin moiety referred to as molybdopterin. Moco is synthesized from GTP by an ancient and conserved biosynthetic pathway that can be divided into four steps involving the biosynthetic intermediates cyclic pyranopterin monophosphate, molybdopterin, and adenylated molybdopterin. In a fifth step, sulfuration or bond formation between Mo and a protein cysteine result in two different catalytic Mo centers. There are four Mo enzymes in plants: (1) nitrate reductase catalyzes the first and rate-limiting step in nitrate assimilation and is structurally similar to the recently identified, (2) peroxisomal sulfite oxidase that detoxifies excessive sulfite. (3) Aldehyde oxidase catalyzes the last step of abscisic acid biosynthesis, and (4) xanthine dehydrogenase is essential for purine degradation and stress response.

Molybdenum cofactor biosynthesis and deficiency

The molybdenum cofactor (Moco) forms the active site of all molybdenum (Mo) enzymes, except nitrogenase. Mo enzymes catalyze important redox reactions in global metabolic cycles. Moco consists of Mo covalently bound to one or two dithiolates attached to a unique tricyclic pterin moiety commonly referred to as molybdopterin (MPT). Moco is synthesized by an ancient and conserved biosynthetic pathway that can be divided into four steps, according to the biosynthetic intermediates precursor Z (cyclic pyranopterin monophosphate), MPT and adenylated MPT. In a fifth step modifications such as attachment of nucleotides, sulfuration or bond formation between Mo and the protein result in different catalytic Mo centers. A defect in any of the steps of Moco biosynthesis results in the pleiotropic loss of all Mo enzyme activities. Human Moco deficiency is a hereditary metabolic disorder characterized by severe neurodegeneration resulting in early childhood death. Recently, a first substitution therapy was established.

[Bile acid-independent effect of hymecromone on bile secretion and common bile duct motility]

BACKGROUND AND OBJECTIVE

Hymecromone (4-methyl-umbiliferone) has been used for more than 20 years for the treatment of functional and obstructive spasms of the biliary tract. Its mode of action however is still largely unknown. We investigated the effect of 4-methyl-umbiliferone p. o. and i. v. on gall bladder and common bile duct motility and studied potentially indirect effects via alterations in bile acid metabolism.

PATIENTS AND METHODS

Twenty healthy volunteers, aged 25 - 37, 10 males, 10 females, were included into a Placebo-controlled, randomised, cross-over double-blind study. Subjects were treated with 800 mg hymecromone p. o.; in addition a standardized meal (Biloptin, 40 gs) was given. Gall bladder volume and common bile duct diameter were determined by ultrasound. Conjugated and unconjugated bile acids were analysed by gas chromatography. Additionally, in a third open label phase hymecromone was given i. v.

RESULTS

Common bile duct diameter was significantly larger after a standard meal with hymecromone given p. o. or i. v. than with placebo (each p < 0.01). However, alterations in gall bladder volume after a standard meal were not different between placebo and hymecromone (p. o. or i. v.). Unconjugated and conjugated bile acids rose after standard meal in all three groups without significant differences between hymecromone and placebo.

CONCLUSIONS

Hymecromone was associated with significant dilation of the common bile duct. In contrast to previous reports an effect of hymecromone on gall bladder motility could not be observed. The unchanged values of bile acids in serum after hymecromone compared to placebo, together with the dilatation of the common bile duct after hymecromone, may indicate a bile acid-independent effect of hymecromone on bile secretion.

The pathogenesis of molybdenum cofactor deficiency, its delay by maternal clearance, and its expression pattern in microarray analysis

Molybdenum cofactor (Moco)-deficiency is a lethal autosomal recessive disease, for which until now no effective therapy is available. The biochemical hallmark of this disorder is the inactivity of the Moco-dependent sulfite oxidase, which results in elevated sulfite and diminished sulfate levels throughout the organism. In humans, Moco-deficiency results in neurological damage, which is apparent in untreatable seizures and various brain dysmorphisms. We have recently described a murine model for Moco-deficiency, which reflects all enzyme and metabolite changes observed in the patients, and an efficient therapy using a biosynthetic precursor of Moco has been established in this animal model. We now analyzed these mice in detail and excluded morphological brain damage, while expression analysis with microarrays indicates a massive cell death program. This neuronal damage appears to be triggered by elevated sulfite levels and is ameliorated in affected embryos by maternal clearance.

[GCP inspections of clinical trials]

The new regulations on clinical trials with medicinal products for human use include rules for Good Clinical Practice (GCP) inspections. These rules pertain to such inspections as part of the surveillance program of the relevant state authorities, in preparation for a decision on the authorization of clinical trials by the federal authorities, and pre and post approval GCP-inspections as one tool of Good Regulatory Practice (GRP). The overall aim of such inspections is to verify compliance with the provisions on GCP and, thus, to ensure the protection of trial subjects, the credibility and reliability of clinical trial results, and the pro-active protection of patients. Since inspection results have to be acknowledged by other member states, there is an increasing importance for quality assurance and harmonization of inspection procedures. As in most cases a considerable number of sites are involved in the conduct of clinical trials in different member states, there is a need for coordination of GCP inspections between these states.

Synthesis of adenylated molybdopterin: an essential step for molybdenum insertion

The molybdenum cofactor (Moco) is part of the active site of all molybdenum (Mo)-dependent enzymes, except nitrogenase. Moco consists of molybdopterin (MPT), a phosphorylated pyranopterin with an enedithiolate coordinating Mo and it is synthesized by an evolutionary old multistep pathway. The plant protein Cnx1 from Arabidopsis thaliana catalyzes with its two domains (E and G) the terminal step of Moco biosynthesis, the insertion of Mo into MPT. Recently, the high-resolution MPT-bound structure of the Cnx1 G domain (Cnx1G) has been determined (Kuper, J., Llamas, A., Hecht, H. J., Mendel, R. R., and Schwarz, G. (2004) Nature 430, 803-806). Besides defining the MPT-binding site a novel and unexpected modification of MPT has been identified, adenylated MPT. Here we demonstrate that it is Cnx1G that catalyzes the adenylation of MPT. In vitro synthesized MPT was quantitatively transferred from Escherichia coli MPT synthase to Cnx1G. The subsequent adenylation reaction by Cnx1G was Mg(2+)- and ATP-dependent. Whereas Mn(2+) could partially replace Mg(2+), ATP was the only nucleotide accepted by Cnx1G. Consequently the formation of pyrophosphate was demonstrated, which was dependent on the ability of Cnx1G to bind MPT. Pyrophosphate, either formed in the reaction or added externally, inhibited the Cnx1G-catalyzed MPT adenylation reaction. Catalytically inactive Cnx1G mutant variants showed impaired MPT adenylation confirming that MPT-AMP is the reaction product of Cnx1G. Therefore Cnx1G is a MPT adenylyltransferase catalyzing the activation of MPT, a universal reaction in the Moco synthetic pathway because Cnx1G is able to reconstitute also bacterial and mammalian Moco biosynthesis.

[Histological investigation of the micromorphological effects of the application of a laser needle--results of an animal experiment]

In an experimental animal study (Sus scrofa domesticus) we investigated the effects of the new technique of laser needle stimulation (wavelength: 685 nm; energy density: 4.6 kJ/cm2 per point; application duration: 20 min). The results revealed changes in microcirculatory parameters of the skin resulting in an increase in blood flow. However, the quality and intensity of the laser light did not induce micromorphological alterations in the skin.

Development and validation of a PCR-based marker assay for negative selection of the HMW glutenin allele Glu-B1-1d (Bx-6) in wheat

Polymorphisms between the coding sequences of high-molecular-weight (HMW) glutenin x-type genes at the Glu-1 locus were used to amplify Glu-1B x-type-specific PCR fragments. PCR analysis in a wheat cultivar subset carrying different Glu-1B x-type alleles resulted in PCR fragments that differed in size for Glu-B1-1d (B-x6) and non -Glu-B1-1d (B-x6) genotypes. Subsequent sequencing analysis revealed a 15-bp in-frame insertion in the coding regions of all Glu-B1-1d (B-x6) genotypes which allowed the development of a B-x6-specific PCR assay for high-throughput allele sizing by ion-pair reversed-phase high-performance liquid chromatography. The assay was validated in a set of 86 German wheat cultivars, and genotyping data unequivocally verified the presence of HMW glutenin subunits GLU-B1-1D (Bx-6) + GLU-B1-2A (By-8) by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis. These results demonstrate that the PCR assay can be applied for the detection and negative selection of the 'poor breadmaking quality' Glu-B1-1d (B-x6) alleles in wheat breeding programs.

Structure of the molybdopterin-bound Cnx1G domain links molybdenum and copper metabolism

The molybdenum cofactor is part of the active site of all molybdenum-dependent enzymes, except nitrogenase. The molybdenum cofactor consists of molybdopterin, a phosphorylated pyranopterin, with an ene-dithiolate coordinating molybdenum. The same pyranopterin-based cofactor is involved in metal coordination of the homologous tungsten-containing enzymes found in archea. The molybdenum cofactor is synthesized by a highly conserved biosynthetic pathway. In plants, the multidomain protein Cnx1 catalyses the insertion of molybdenum into molybdopterin. The Cnx1 G domain (Cnx1G), whose crystal structure has been determined in its apo form, binds molybdopterin with high affinity and participates in the catalysis of molybdenum insertion. Here we present two high-resolution crystal structures of Cnx1G in complex with molybdopterin and with adenylated molybdopterin (molybdopterin-AMP), a mechanistically important intermediate. Molybdopterin-AMP is the reaction product of Cnx1G and is subsequently processed in a magnesium-dependent reaction by the amino-terminal E domain of Cnx1 to yield active molybdenum cofactor. The unexpected identification of copper bound to the molybdopterin dithiolate sulphurs in both structures, coupled with the observed copper inhibition of Cnx1G activity, provides a molecular link between molybdenum and copper metabolism.

Linking the synapse to the cytoskeleton: a breath-taking role for microfilaments

Cytoskeletal elements, in particular microtubules and microfilaments, are essential players in a large variety of phenomena requiring cellular and intracellular motility. To name but a few, they are intimately involved in determining cell shape and adhesion, establishment and maintenance of polarity, locomotion and organelle transport in all eukaryotic cells, including neurons. Here, we would like to focus on the synapse in the vertebrate central nervous system, proposing a model for a specific dialogue between neuronal microfilaments and other protein components in neurotransmission and synaptic plasticity.

The crystal structure of plant sulfite oxidase provides insights into sulfite oxidation in plants and animals

The molybdenum cofactor (Moco) containing sulfite oxidase (SO) from Arabidopsis thaliana has recently been identified and biochemically characterized. The enzyme is found in peroxisomes and believed to detoxify excess sulfite that is produced during sulfur assimilation, or due to air pollution. Plant SO (PSO) is homodimeric and homologous to animal SO, but contains only a single Moco domain without an additional redox center. Here, we present the first crystal structure of a plant Moco enzyme, the apo-state of Arabidopsis SO at 2.6 A resolution. The overall fold and coordination of the Moco are similar to chicken SO (CSO). Comparisons of conserved surface residues and the charge distribution in PSO and CSO reveal major differences near the entrance to both active sites reflecting different electron acceptors. Arg374 has been identified as an important substrate binding residue due to its conformational change when compared to the sulfate bound structure of CSO.