CFA-15 – a perfluorinated metal–organic framework with linear 1-D CuII-chains containing accessible unsaturated, reactive metal centres

The synthesis and crystal structure of the perfluorinated metal–organic framework CFA-15, CuII3(tfpc)₂(OH)₂·DMF, and the organic ligand H₂-tfpc, 3,5-bis(trifluoromethyl)-1H-pyrazole-4-carboxylic acid, are described.

Hairpins in the conformations of a confined polymer

If a semiflexible polymer confined to a narrow channel bends around by 180°, the polymer is said to exhibit a hairpin. The equilibrium extension statistics of the confined polymer are well understood when hairpins are vanishingly rare or when they are plentiful. Here, we analyze the extension statistics in the intermediate situation via experiments with DNA coated by the protein RecA, which enhances the stiffness of the DNA molecule by approximately one order of magnitude. We find that the extension distribution is highly non-Gaussian, in good agreement with Monte-Carlo simulations of confined discrete wormlike chains. We develop a simple model that qualitatively explains the form of the extension distribution. The model shows that the tail of the distribution at short extensions is determined by conformations with one hairpin.

CFA-14 – a perfluorinated metal–organic framework with linear 1-D CoII-chains showing temperature dependent spin-chain magnetic ordering

The synthesis and crystal structure of the perfluorinated MOF CFA-14 CoII2(tfpb)(OH)₂ (H₂-tfpb = 1,4-bis(3,5-bis(trifluoromethyl)-1H-pyrazole-4-yl)benzene) are described.

Melanoma cell adhesion can be blocked by heparin in vitro: Suggestion of VLA-4 as a novel target for antimetastatic approaches

The clinical benefit of heparin in cancer patients to prolong survival can be attributed to non-anticoagulant mechanisms. Since adhesion molecules are crucially involved in tumour cell metastasis, their inhibition offers an attractive approach for interfering with the metastatic cascade. Heparin is known to attenuate metastasis in a selectin-dependent manner and possessesa variety of additional effects that are thought to influence tumour cell dissemination, proliferation, and angiogenesis. We investigated the adhesion behaviour of B16F10 melanoma cells in vitro regarding selectin- and VLA-4/VCAM-1-mediated binding to get an insight into underlying mechanisms of melanoma cell metastasis. We show that B16F10 cells display binding ability to P- and L-selectin as well as to isolated platelets. In contrast, B16F10 cells did not adhere to immobilized P-selectin under flow. This contributes to recent findings that elucidate a major role of platelet P-selectin for microemboli formation and thus, facilitating metastasis. In contrast, B16F10 cells adhered to endothelial cells under flow, which could partly be inhibited by a function-blocking anti-VCAM-1 mAb. To emphasizeVCAM-1 function, we analyzed cell adhesion at immobilizedVCAM-1 and observed an integrin dependency. Inhibition experiments reveal that heparin influences VLA-4-mediated binding pathways. By a combination of different techniques we prove that the site of heparin action is ratherVLA-4 thanVCAM-1.To our knowledge, this is the first time that heparin is shown to interfere with theVLA-4/VCAM-1 interaction leading to the suggestion of a novel heparin target. Our results may contribute to the understanding of how heparin exerts its anti-metastatic activity.

CFA-13 - a bifunctional perfluorinated metal-organic framework featuring active Cu(i) and Cu(ii) sites

The synthesis and crystal structure of the mixed-valent perfluorinated metal-organic framework (Me₂NH₂)[CFA-13] (Coordination Framework Augsburg University-13), (Me₂NH₂)[CuCu(tfpc)₄] (H₂-tfpc = 3,5-bis(trifluoromethyl)-1H-pyrazole-4-carboxylic acid) is described. The copper-containing MOF crystallizes in the monoclinic crystal system within the space group P2₁/n (no. 14) and the unit cell parameters are as follows: a = 22.3887(19), b = 13.6888(8), c = 21.1804(13) Å, β = 90.495(3)°, V = 6491.0(8) ų. (Me₂NH₂)[CFA-13] features a porous 3-D structure constructed from two types of secondary building units (SBUs). Besides novel trinuclear [Cu(pz)₄]^- coordination units, the network also exhibits Cu(ii) paddle-wheel SBUs. (Me₂NH₂)[CFA-13] is fully characterized by single crystal X-ray diffraction, thermogravimetric analysis, variable temperature powder X-ray diffraction, IR spectroscopy, photoluminescence, gas sorption measurements and pulse chemisorption experiments. M[CFA-13] (M = K⁺, Cs⁺) frameworks were prepared by postsynthetic exchange of interchannel dimethylammonium cations. Moreover, it was shown that CO molecules can be selectively bound at Cu(i) sites of [Cu(pz)₄]^- units, whereas Cu(ii) paddle-wheel units bind selectively NH₃ molecules.

CFA-4 – a fluorinated metal–organic framework with exchangeable interchannel cations

Fluorinated metal–organic framework M[CFA-4] contains exchangeable interchannel cations and shows interesting selective and sensitive fluorescence behaviour towards nitroaromatics.

Extension of nanoconfined DNA: Quantitative comparison between experiment and theory

The extension of DNA confined to nanochannels has been studied intensively and in detail. However, quantitative comparisons between experiments and model calculations are difficult because most theoretical predictions involve undetermined prefactors, and because the model parameters (contour length, Kuhn length, effective width) are difficult to compute reliably, leading to substantial uncertainties. Here we use a recent asymptotically exact theory for the DNA extension in the "extended de Gennes regime" that allows us to compare experimental results with theory. For this purpose, we performed experiments measuring the mean DNA extension and its standard deviation while varying the channel geometry, dye intercalation ratio, and ionic strength of the buffer. The experimental results agree very well with theory at high ionic strengths, indicating that the model parameters are reliable. At low ionic strengths, the agreement is less good. We discuss possible reasons. In principle, our approach allows us to measure the Kuhn length and the effective width of a single DNA molecule and more generally of semiflexible polymers in solution.

Fast size-determination of intact bacterial plasmids using nanofluidic channels

We demonstrate how nanofluidic channels can be used as a tool to rapidly determine the number and sizes of plasmids in bacterial isolates. Each step can be automated at low cost, opening up opportunities for general use in microbiology labs.

Visualizing the entire DNA from a chromosome in a single frame

The contiguity and phase of sequence information are intrinsic to obtain complete understanding of the genome and its relationship to phenotype. We report the fabrication and application of a novel nanochannel design that folds megabase lengths of genomic DNA into a systematic back-and-forth meandering path. Such meandering nanochannels enabled us to visualize the complete 5.7 Mbp (1 mm) stained DNA length of a Schizosaccharomyces pombe chromosome in a single frame of a CCD. We were able to hold the DNA in situ while implementing partial denaturation to obtain a barcode pattern that we could match to a reference map using the Poland-Scheraga model for DNA melting. The facility to compose such long linear lengths of genomic DNA in one field of view enabled us to directly visualize a repeat motif, count the repeat unit number, and chart its location in the genome by reference to unique barcode motifs found at measurable distances from the repeat. Meandering nanochannel dimensions can easily be tailored to human chromosome scales, which would enable the whole genome to be visualized in seconds.

Case report: High chromium and cobalt levels in a pregnant patient with bilateral metal-on-metal hip arthroplasties

BACKGROUND

Metal-on-metal bearings frequently are used in young patients leading to the concern that disseminated metals such as chromium (Cr) and cobalt (Co) as the main constituents could affect pregnancies.

CASE DESCRIPTION

We describe a 41-year-old patient with bilateral metal-on-metal hip arthroplasties, a recurrent pseudotumor, and extremely high blood levels (Cr 39 μg/L, Co 138 μg/L) at 12 gestational weeks. At different gestational weeks, maternal blood, aspirate of the pseudotumor, and amniotic fluid were analyzed for Cr and Co. Therapy with chelating agents was not recommended because the mother showed no symptoms of toxicity and the safety of chelating therapy during pregnancy is not established. At 38 weeks of gestation, a healthy male infant was delivered with elevated Cr and Co cord blood levels. At the age of 8 weeks, the infant's Cr was comparable to the cord blood level, whereas the Co decreased considerably without treatment. At the age of 14 weeks, the infant's development was seemingly uneventful and no signs of toxicity were obvious.

LITERATURE REVIEW

Carcinogenic, mutagenic, and teratogenic potentials of these metals have been suggested. However, we found no published clinical observations in context with pregnancies of women with hip arthroplasties using metal-on-metal implants. To our knowledge, this is the first report of such high levels of Cr and Co in a human pregnancy.

PURPOSES AND CLINICAL RELEVANCE

Although we cannot generalize from one case, the seemingly uneventful outcome of this pregnancy may reassure colleagues when counseling patients with high ion levels whether to carry a pregnancy to term.

Structural dynamics and interfacial properties of filler-reinforced elastomers

The combined effect of filler networking and reduced chain mobility close to the filler interface is analyzed based on investigations of the relaxation dynamics of a solution of styrene butadiene rubber filled with different loadings and types of nanostructured carbon blacks. Dynamic-mechanical and dielectric spectra are studied in a wide frequency and temperature range. By referring to a tunneling process of charge carriers over nanoscopic gaps between adjacent carbon black particles the gap distance is evaluated from the dielectric spectra. This distance corresponds to the length of glassy-like polymer bridges forming flexible bonds between adjacent filler particles of the filler network. It is found that the gap distance decreases with increasing filler loading and specific surface area which correlates with an increase of the apparent activation energy of the filler network evaluated from dynamic-mechanical data. Due to the thermal activation of glassy-like polymer bridges the time-temperature superposition principle is not fulfilled for filled elastomers and the introduction of vertical shift factors is necessary to obtain viscoelastic master curves. The change in the low frequency viscoelastic properties by the incorporation of fillers is shown to be related to the superimposed dynamics of the filler network governed by the viscoelastic response of the glassy-like polymer bridges. This effect is distinguished from the reduced chain mobility close to the filler surface which results in a broadening of the glass transition on the high temperature or low frequency side. The microstructure-based interpretation of viscoelastic data is supported by an analysis of the relaxation time spectra.

Binding between heparin and the integrin VLA-4

Heparin possesses antimetastatic effects that were related to various molecular mechanisms beyond anticoagulant activities. The ability of heparin to interfere with the function of adhesion receptors in the metastatic course appears as a promising therapeutic approach. This refers to numerous findings that heparin attenuates metastasis in a selectin-dependent manner. We recently demonstrated that heparin interferes with the integrin VLA-4 on murine melanoma cells binding to VCAM-1. To confirm this activity and to obtain further insight into molecular recognition of heparin by VLA-4, we investigated the inhibition of VLA-4 mediated binding of human melanoma MV3 cells to immobilised VCAM-1 by different heparins. The size of heparin has an important impact on inhibition. Unfractionated heparin (UFH) and tinzaparin, a low-molecular-weight heparin (LMWH) representing a mean of about 18-20 monomers, displayed high inhibitory activity. Fractionating tinzaparin to 14-18 monomers reduced inhibition slightly, while the pentasaccharide fondaparinux was without effects. To confirm molecular recognition of tinzaparin by VLA-4, a surface acoustic wave-biosensor was applied. A VLA-4 containing membrane preparation of MV3 cells was immobilised at the sensors to allow for detection of kinetic binding constants of tinzaparin compared to VCAM-1. Tinzaparin binds to VLA-4 with affinity in the low micromolar range (4.61 x 10(-6) M), which clearly indicates specific molecular recognition. Furthermore, tinzaparin displays a nearly identical k(off) compared to VCAM-1 (5.13 x 10(-3) s(-1) versus 3.44 x 10(-3) s(-1)) which is evident for interference with the ligand binding. The data provide evidence for a direct confirmation of heparin binding to VLA-4 and thus, contribute to understand the antimetastatic activity of heparin.

Melanoma cell adhesion can be blocked by heparin in vitro: suggestion of VLA-4 as a novel target for antimetastatic approaches

The clinical benefit of heparin in cancer patients to prolong survival can be attributed to non-anticoagulant mechanisms. Since adhesion molecules are crucially involved in tumour cell metastasis, their inhibition offers an attractive approach for interfering with the metastatic cascade. Heparin is known to attenuate metastasis in a selectin-dependent manner and possesses a variety of additional effects that are thought to influence tumour cell dissemination, proliferation, and angiogenesis. We investigated the adhesion behaviour of B16F10 melanoma cells in vitro regarding selectin- and VLA-4/VCAM-1-mediated binding to get an insight into underlying mechanisms of melanoma cell metastasis. We show that B16F10 cells display binding ability to P- and L-selectin as well as to isolated platelets. In contrast, B16F10 cells did not adhere to immobilized P-selectin under flow. This contributes to recent findings that elucidate a major role of platelet P-selectin for microemboli formation and thus, facilitating metastasis. In contrast, B16F10 cells adhered to endothelial cells under flow, which could partly be inhibited by a function-blocking anti-VCAM-1 mAb. To emphasize VCAM-1 function, we analyzed cell adhesion at immobilized VCAM-1 and observed an integrin dependency. Inhibition experiments reveal that heparin influences VLA-4-mediated binding pathways. By a combination of different techniques we prove that the site of heparin action is rather VLA-4 than VCAM-1. To our knowledge, this is the first time that heparin is shown to interfere with the VLA-4/VCAM-1 interaction leading to the suggestion of a novel heparin target. Our results may contribute to the understanding of how heparin exerts its anti-metastatic activity.

Kinetic Analysis of Heparin and Glucan Sulfates Binding to P-Selectin and Its Impact on the General Understanding of Selectin Inhibition

P-Selectin, expressed on activated endothelial cells and platelets, is a high kinetic adhesion receptor involved in leukocyte rolling of the inflammatory response, or in tumor cell binding in the course of metastasis. Thus, P-selectin inhibition is a promising therapeutic target. The anti-inflammatory and anti-metastatic activities of heparin have partly been related to the inhibition of P-selectin binding. Here we apply a quartz crystal microbalance (QCM) biosensor to determine the kinetic constants of heparin and other sulfated polysaccharides binding to immobilized P-selectin. Binding kinetics of the derivatives were correlated with their inhibitory capacity in a P-selectin cell rolling assay. Three commercial heparins differ in cell rolling inhibition and display slightly different affinities (KD 1.21 x 10(-6) M to 5.86 x 10(-7) M). Inhibitory capacity appears to be mainly driven by a slow off-rate from the receptor (2.27 x 10(-3) s-1 to 1.23 x 10(-3) s-1). To correlate the impact of binding kinetics on inhibitory capacity structurally, we analyzed six semisynthetic glucan sulfates. They display different degrees of sulfation (DS), which has a strong influence on inhibitory activity. Kinetic data illustrate that the inhibitory capacity correlates excellently with the off-rate of these polysaccharides (R = 0.99), while the association (on-rate) affects activity to a lesser extent. In general, the consideration of binding kinetics sheds new light on the mechanism of selectin inhibition. A much slower dissociation of the inhibitors from the receptor than the physiological ligands is key for inhibitory capacity. Structurally, highly charged compounds with a slow off-rate, such as heparin or glucan sulfates, appear as potent candidates for P-selectin inhibition.

The influence of various structural parameters of semisynthetic sulfated polysaccharides on the P-selectin inhibitory capacity

Selectin-mediated leukocyte rolling along the endothelium is of key importance for maintaining the cellular immune response. The anti-inflammatory activities of heparin have partly been related to inhibition of P-selectin binding. Heparin, however, suffers from its heterogeneous variable structure, the animal origin and multiple in vivo effects. As P-selectin is a promising target for anti-inflammatory approaches, we focused on P-selectin inhibition by other sulfated polysaccharides and compared them with six heparins. We examined 15 structurally defined semisynthetic sulfated glucans, non-animal-derived from the linear glucans phycarin, curdlan or pullulan. The derivatives gradually differ in their degree of sulfation, molecular weight, and glycosidic linkage. The inhibitory capacity was analysed in a parallel plate flow chamber, detecting the rolling of U937 cells on P-selectin layers. Unfractionated heparins displayed variabilities between different preparations. Considering fractionated heparins, exceeding of a minimal mass is essential for activity. Comparing the glucan sulfates, charge density is the most important parameter for P-selectin binding. Highly sulfated derivatives are excellent inhibitors, the reduced cell binding up to 16.2+/-6.4% strongly exceeded the heparin activities. Molecular weight is of minor effects, while glycosidic backbone linkage holds certain importance. To check the P-selectin inhibition in vivo, heparin and one phycarin sulfate were tested using intravital microscopy of microvasculature in mice. Both compounds significantly reduced the rolling fractions of activated platelets on endothelium as effective as a blocking P-selectin antibody. Our study indicates that semisynthetic glucan sulfates with optimal structures block P-selectin excellently and might become promising candidates for anti-inflammatory drugs to replace heparin for certain applications.

Local observation of reverse-domain superconductivity in a superconductor-ferromagnet hybrid

Nanoscale magnetic and superconducting properties of the superconductor-ferromagnet Nb/PbFe12O19 hybrid were studied as a function of applied magnetic fields. Low-temperature scanning laser microscopy (LTSLM) together with transport measurements were carried out in order to reveal local variations of superconductivity induced by the magnetic field template produced by the ferromagnetic substrate. Room temperature magnetic force microscopy (MFM) was performed and magnetization curves were taken at room and low temperature to investigate the magnetic properties of the hybrid. Comparative analysis of the LTSLM and the MFM images has convincingly demonstrated the presence of the reverse-domain superconductivity.

Zirconium oxide restorations with the DCS precident system

The DCS Precident system is suitable for the dental practice and enables the processing of different materials and dental structures. The surface is acquired precisely and without contact by means of a semiconductor laser. Easy-to-use software is employed for the three-dimensional design of the restorations. An almost fully automatic milling machine efficiently mills the framework. A clinical case is documented.

[Clinical results following revision of covered goniotrepanation (Elliot-Fronimopoulos)]

Among 128 patients with glaucoma, 19 underwent a revision of a goniotrepanation with scleral flap. Adequate regulation of IOP was achieved in this way, in some cases with additional medication. This revision of the filtering bleb can be recommended as the operation of choice for all forms of glaucoma in which goniotrepanation with scleral flap was performed and in which pressure could not be regulated with additional medication.

Early detection of aortic dilatation in ankylosing spondylitis using echocardiography

Aortic root abnormalities including cusp thickening, subvalvular stenosis, and mild aortic root dilatation are the most common cardiac complications in patients with long standing ankylosing spondylitis (AS). Twenty-three patients with definite idiopathic AS (New York Criteria 1966) and twenty-two matched controls were studied with M-mode echocardiography. Only one of the AS patients had clinical aortic incompetence. Six of the AS patients had mildly dilated aortic roots (normal less than 3.7 cm) with a mean diameter of 3.9 cm (range 3.8 to 4.00 cm). None of the twenty-two controls matched for age, sex and blood pressure had dilated aortic roots, with a mean diameter of 3.3 cm (range 2.9 to 3.6 cm). No correlation existed between aortic dilatation and severity of disease estimated by acute phase proteins--caerulo plasmin, alpha 1-antitrypsin, alpha 1 acid glycoprotein, ferritin and C Reactive protein. Contrary to a previous report, mild aortic root dilatation occurs in long standing cases of AS. Although it is a non-specific finding, it does not appear to be related to age or blood pressure and may therefore be the forerunner of aortic incompetence.

Comparison of iopamidol, ioxaglate, and diatrizoate during coronary arteriography in dogs

Iopamidol and ioxaglate are two new contrast media which have an osmolality approximately half that of diatrizoate for the same iodine concentration. These three contrast media were compared with each other and with Hartmann's solution during coronary arteriography in dogs using hemodynamic and electrocardiographic parameters in addition to coronary venous sinus sampling to measure changes in osmolality, electrolyte, and contrast media concentration. Iopamidol and ioxaglate had similar, but less toxic, effects in comparison with diatrizoate. These new contrast media may offer a reduction in the morbidity and mortality of coronary arteriography.

Effects of phospholipase A2 and albumin on the calcium-dependent ATPase and the lipid composition of sarcoplasmic membranes

1. The calcium-dependent ATPase activity of phospholipase-A2-digested sarcoplasmic vesicles decreases concomitantly with the contents of residual lysophospholipids and fatty acids when increasing albumin concentrations are applied. 2. Delipidated albumin preferentially removes unsaturated fatty acids and lysophosphatidylcholine. A complete removal of the phospholipids by albumin does not occur. 3. The membrane-bound lysophospholipids were analysed with respect to type of phospholipid, plasmalogen content and fatty acid chains by means of thin-layer chromatography and gas chromatography. 4. While the fatty acid composition of the lysophospholipids is independent of the degree of delipidation, the composition of the residual free fatty acids is found to change with the albumin concentration. 5. Reactivation of the Ca2+-ATPase by oleate leads to reasonable activities at room temperature as long as a minimum of about 30 lysophospholipid molec-les per ATPase is left. The course of the residual Ca2+-ATPase activity with the degree of delipidation is related to the presence of unsaturated fatty acids. 6. No specific role of either sphingomyelin or the plasmalogens has been found.

Effect of 1,25-dihydroxycholecalciferol on impaired calcium transport by the sarcoplasmic reticulum in experimental uremia

In the fragmented sarcoplasmic reticulum from skeletal muscle of rabbits with experimental uremia, defective calcium ion transport is found. An impairment of all parameters is observed (initial rate of uptake, storing capacity with and without oxalate, and concentrating ability). In vivo administration of 1,25-dihydroxycholecalciferol (1,25-(OH)2-vitamin D3)(2 X 27 ng X kg of body wt-1 X day-1 and 6 X 27 ng X kg-1 X day-1, respectively) improved the kinetic parameters. The low dose improved storing capacity, and the higher dose, in addition to the storing capacity, also corrected concentrating ability and the initial rate of uptake. It is concluded that active calcium transport in the sarcoplasmic reticulum is impaired by uremia and that this defect is responsive to the administration of 1,25-(OH)2-vitamin D3.