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Selected AbstractsSynthesis and calcium channel modulating effects of modified Hantzsch nitrooxyalkyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(pyridinyl or 2-trifluoromethylphenyl)-5-pyridinecarboxylatesDRUG DEVELOPMENT RESEARCH, Issue 4 2000Ramin Miri Abstract A group of racemic nitrooxyalkyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(pyridinyl or 2-trifluoromethylphenyl)-5-pyridinecarboxylates 8a,o were synthesized using modified Hantzsch reactions. In vitro calcium channel antagonist activities, determined using a guinea pig ileum longitudinal smooth muscle (GPILSM) assay, showed that compounds 8a,o exhibited weaker calcium antagonist activity (10,5 to 10,7 M range) than the reference drug nifedipine (IC50 = 1.43 × 10,8 M). Compounds 8 possessing a C-4 R1 = 2-pyridyl substituent were always more potent than the approximately equiactive analogs having an R1 = 3-pyridyl, 4-pyridyl or 2-CF3 -C6H4 -substituent, within each subgroup of nitrooxyalkyl compounds [R2 = , (CH2)nONO2 (n = 2, 3, 4) or ,CH(CH2ONO2)2]. Although the length of the R2 = ,(CH2)nONO2 substituent (n = 2,4) was not a determinant of smooth muscle calcium antagonist activity when the C-4 R1 -substituent was 2-pyridyl, when R1 was a 3-pyridyl, 4-pyridyl, or 2-CF3 -C6H4 -substituent, the relative potency order with respect to the R2 = ,(CH2)nONO2 substituent was n = 3 and 4 > n = 2. Replacement of the isopropyl substituent of the ester moiety of the calcium antagonist (±)-2-pyridyl 3a by a ,(CH2)nONO2 (n = 2,4) moiety increased calcium antagonist activity on GPILSM by 8-fold. In contrast, replacement of the isopropyl substituent of the ester moiety of the calcium agonists (±)-3-pyridyl 3b, (±)-4-pyridyl 3c or the methyl substituent of the ester moiety of Bay K8644 by a R2 nitrooxyalkyl substituent resulted in abolition of their calcium agonist effects on GPILSM that is replaced by a smooth muscle calcium antagonist effect. These calcium antagonist data support the concept that incorporation of a nitrooxyalkyl ester substituent constitutes a valuable drug design strategy to enhance Hantzsch 1,4-dihydropyridine calcium antagonist and/or abolish calcium agonist effects on smooth muscle. Replacement of the isopropyl (8b,c), or the methyl (8d) group by a ,CH2CH2ONO2 moiety resulted in retention of the cardiac positive inotropic effect where the relative potency order with respect to the C-4 substituent was 2-CF3 -C6H6 - (8d) > 3-pyridyl (8b) , 4-pyridyl (8c). Model hybrid (calcium channel modulation, ·NO release) compounds, that exhibit dual cardioselective agonist / smooth muscle selective antagonist activities, represent a novel type of 1,4-dihydropyridine CC modulator that offers a potential approach to drug discovery targeted toward the treatment of congestive heart failure and for use as probes to study the structure,function relationship of calcium channels. Drug Dev. Res. 51:225,232, 2000. © 2001 Wiley-Liss, Inc. [source] Hantzsch 1,4-dihydropyridines containing a nitrooxyalkyl ester moiety to study calcium channel antagonist structure,activity relationships and nitric oxide releaseDRUG DEVELOPMENT RESEARCH, Issue 4 2000Jeffrey-Tri Nguyen Abstract A group of 3-nitrooxyalkyl 5-alkyl 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates were prepared using a modified Hantzsch reaction that involved the condensation of a nitrooxyalkyl acetoacetate with an alkyl 3-aminocrotonate and a pyridinecarboxaldehyde. 1H NMR nuclear Overhauser enhancement (nOe) studies for 3-(3-nitrooxypropyl) 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-(2-pyridyl)-3,5-pyridinedicarboxylate (17) indicates a predominant rotamer exists in solution where the pyridyl nitrogen atom is orientated above the 1,4-DHP ring system, and the pyridyl nitrogen atom is antiperiplanar to the 1,4-DHP ring H-4 proton. Variable temperature 1H NMR studies (,30 to +60°C) showed the 1,4-DHP NH proton in 17 is H-bonded in CHCl3 solution. This interaction is believed to be due to intermolecular H-bonding between the pyridyl nitrogen free electron pair and the 1,4-DHP NH proton. In vitro calcium channel antagonist (CCA) activities were determined using a muscarinic-receptor-mediated Ca+2 -dependent contraction of guinea pig ileal longitudinal smooth muscle assay. This class of compounds exhibited lower CCA activity (IC50 = 5.3 × 10,6 to 3.5 × 10,8 M range) than the reference drug nifedipine (IC50 = 1.4 × 10,8 M). For compounds having C-3 ,CH2CH2ONO2 and C-4 pyridyl substituents, the C-5 alkyl was a determinant of CCA (i -Pr > the approximately equipotent i -Bu, t -Bu, and Et analogs). The point of attachment of the isomeric C-4 pyridyl substituent was a determinant of CCA when C-3 ,CH2CH2ONO2 and C-5 i -Pr substituents were present providing the potency profile 2-pyridyl , 3-pyridyl > 4-pyridyl. CCA with respect to the C-3 nitrooxyalkyl substituent was inversely dependent on the length of the alkyl spacer. The percent nitric oxide (·NO) released in vitro by this group of compounds (range of 0.03,0.43%/ONO2 group), quantified as nitrite by reaction with the Griess reagent, was lower than that for the reference drug glycerol trinitrate (3.81%/ONO2 group). Nitric oxide release studies showed that the %·NO released was dependent on the number of ONO2 groups/molecule. A QSAR study for this group of compounds showed a correlation between the specific polarizability descriptor (SpPol) and %·NO release. Drug Dev. Res. 51:233,243, 2000. © 2001 Wiley-Liss, Inc. [source] Electrochemical Evaluation of Nucleoside Analogue Lamivudine in Pharmaceutical Dosage Forms and Human SerumELECTROANALYSIS, Issue 20 2005Burcu Dogan Abstract Lamivudine (LAM) is a synthetic nucleoside analogue with activity against human immunodeficiency virus-type 1 (HIV-1) and Hepatitis B virus (HBV). The aim of this study was to determine LAM levels in serum and pharmaceutical formulations, by means of electrochemical methods using hanging mercury drop electrode (HMDE). On this electrode, LAM undergoes irreversible reduction at the peak potential near Ep,1.26,V (vs. Ag/AgCl/3,M KCl). Reduction LAM signals were measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square-wave voltammetry (OSW). DPV and OSW techniques for the determination of LAM in acetate buffer at pH,4.5, which allows quantitation over the 4×10,6 to 1×10,4,M range in supporting electrolyte for both methods, were proposed. The linear response was obtained in acetate buffer in the ranges of 2×10,6 to 2×10,4,M for spiked serum samples at pH,4.5 for both techniques. The repeatability and reproducibility of the methods for all media were determined. The standard addition method was used in serum. Precision and accuracy were also checked in all media. No electroactive interferences from the endogenous substances were found in serum. With respect to side effects of high doses and short half-life of LAM, a fast and simple detection method is described in this study. [source] Microscale characterization of the binding specificity and affinity of a monoclonal antisulfotyrosyl IgG antibodyELECTROPHORESIS, Issue 12 2008Klaus S. Lassen Dr. Abstract Sulfation is a potentially important post-translational modification of proteins and has been demonstrated in a number of polypeptides, notably in gastrointestinal hormones. In contrast to phosphorylation, however, the investigation of sulfation patterns in tissues and on purified proteins has been complicated by the absence of specific immunoreagents (antibodies) for this modification as well as the chemical lability of the sulfate group. Here, we investigate the properties of a novel mAb against sulfated tyrosyl groups (anti-Tyr(SO3H) antibody) using CE and a panel of sulfated and nonsulfated peptides and proteins. The data show that the anti-Tyr(SO3H) antibody is completely specific for compounds containing sulfated tyrosyls. Affinity electrophoresis experiments allowed us to estimate dissociation constants for sulfated hirudin fragment (56,65), gastrin-17, and cholecystokinin octapeptide (CCK8) in the 1,3,,M range. The affinity of the antibody toward complement 4 protein that contains three sulfotyrosines was analyzed by surface plasmon resonance technology and modeled according to a bivalent-binding model which yielded a Kd1 of 20.1,,M for the monovalent complex. The same binding was studied by CE and found to be in the micromolar scale albeit with some uncertainty due to complex separation patterns. The work illustrates the amount of information on antibody,antigen interactions that may be obtained with microelectrophoretic methods consuming minute quantities of material. Furthermore the specificity of this antibody could be confirmed in one operation using an array of sulfated and nonsulfated compounds. [source] Synthesis of 2,4-diaminopyrido[2,3- d]pyrimidines and 2,4-diamino-quinazolines with bulky dibenz[b,f]azepine and dibenzo[a,d]-cycloheptene substituents at the 6-position as inhibitors of dihydrofolate reductases from pneumocystis carinii, toxoplasma gondii, and mycobacterium avium,JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2000Andre Rosowsky The synthesis of four previously undescribed 2,4-diaminopyrido[2,3- d]pyrimidines (3,4) and 2,4-diaminoquinazolines (5,6) with a bulky tricyclic aromatic group at the 6-position is described. Condensation of dibenz[b,f]azepine with 2,4-diamino-6-bromomethylpyrido[2,3- d]pyrimidine (8) and 2,4-diamino-6-bromomethylquinazoline (17) in the presence of sodium hydride afforded N -[(2,4-diaminopyrido[2,3- d]-pyrimidin-6-yl)methyl]dibenz[b,f]azepine (3) and N -[(2,4-diaminoquinazolin-6-yl)methyl]dibenz[b,f]-azepine (4), respectively. Condensation of 5-chlorodibenzo[a,d]cycloheptene (19) and 5-chloro-10,11-dihydrodibenzo[a,d]cycloheptene (20) with 2,4,6-triaminoquinazoline (13) afforded 5-[(2,4-diamino-quinazolin-6-yl)amino]-5H -dibenzo[a,d]cycloheptene (5) and the corresponding 10,11-dihydro derivative (6), respectively. The bromides 8 and 17, as hydrobromic acid salts, were obtained from the corresponding nitriles according to a standard three-step sequence consisting of treatment with Raney nickel in formic acid followed by reduction with sodium borohydride and bromination with dry hydrogen bromide in glacial acetic acid. Compounds 3,6 were evaluated in vitro for the ability to inhibit dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, Mycobacterium avium, and rat liver. Compounds 3 and 4 were potent inhibitors of all four enzymes, with IC50 values in the 0.03,0.1 ,M range, whereas 5 was less potent. However the selectivity of all four compounds for the parasite enzymes relative to the rat enzyme was<10-fold, whereas the recently reported lead compound in this series, N -[(2,4-diaminopteridin-6-yl)methyl]dibenz[b,f]azepine (1) has > 100-fold selectivity for the T. gondii and M. avium enzyme and 21-fold selectivity for the P carinii enzyme. [source] Secondary conformation of short lysine- and leucine-rich peptides assessed by optical spectroscopies: Effect of chain length, concentration, solvent, and timeBIOPOLYMERS, Issue 1 2006Belén Hernández Abstract Solution secondary structures of three synthetic cationic peptides, currently used in antisense oligonucleotide delivery into living cells, have been analyzed by means of circular dichroism (CD) and Raman scattering in different buffers as a function of concentration and time. All three peptides are of minimalist conception, i.e., formed by only two types of amino acids (leucine: L and lysine: K). Two of these peptides contain 15 aminoacids: Nter - KLLKLLLKLLLKLLK (L10K5), Nter -KLKLKLKLKLKLKLK (L7K8), and the third one has only 9 residues: Nter -KLKLKLKLK (L4K5). The conformational behavior of the 15-mers in pure water differs considerably one from another. Although both of them are initially disordered in the 50,350 ,M range, L10K5 gradually undergoes a disordered to , -helix transition for molecular concentrations above 100 ,M. In all other solvents used, L10K5 adopts a stable , -helical conformation. In methanol and methanol/Tris mixture, nonnative , -helices can be induced in both KL-alternating peptides, i.e., L7K8 and L4K5. However, in major cases and with a time delay depending on peptide concentration, , -like structures can be gradually formed in both solutions. In PBS and methanol/PBS mixture, the tendency for L7K8 and L4K5 is to form structures belonging to , -family. A discussion has been undertaken on the effect of counterions as well as their nature in the stabilization of ordered structures in both KL-alternating peptides. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 8,19, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Phenolic Oxime Oligomers Inhibit Alzheimer's Amyloid Fibril Formation and Disaggregate Fibrils In VitroCHEMBIOCHEM, Issue 8 2009Gunnar T. Dolphin Dr. Abstract See you later amyloid ,: A screen of a small library of oxime oligomers with an HTS fluorescence assay for amyloid fibril inhibition and subsequent investigation by atomic force microscopy revealed two new micromolar inhibitors of amyloid fibril formation. These new inhibitors have IC50 values in the 10 ,M range. [source] Searching for Disease Modifiers,PKC Activation and HDAC Inhibition,A Dual Drug Approach to Alzheimer's Disease that Decreases A, Production while Blocking Oxidative StressCHEMMEDCHEM, Issue 7 2009Abstract A series of benzolactam compounds were synthesized, some of which caused a concentration-dependent increase in sAPP, and decrease in A, production in the concentration range of 0.1,10,,M. Moreover, some compounds showed neuroprotective effects in the 10,20,,M range in the HCA cortical neuron model of oxidative stress and no toxicity in measurements of neuron viability by MTT assay, even at the highest concentrations tested (20,,M). Alzheimer's disease (AD) is a well-studied neurodegenerative process characterized by the presence of amyloid plaques and neurofibrillary tangles. In this study, a series of protein kinase,C (PKC) activators were investigated, some of which also exhibit histone deacetylase (HDAC) inhibitory activity, under the hypothesis that such compounds might provide a new path forward in the discovery of drugs for the treatment of AD. The PKC-activating properties of these drugs were expected to enhance the ,-secretase pathway in the processing of amyloid precursor protein (APP), while their HDAC inhibition was anticipated to confer neuroprotective activity. We found that benzolactams 9 and 11,14 caused a concentration-dependent increase in sAPP, and decrease in ,-amyloid (A,) production in the concentration range of 0.1,10,,M, consistent with a shift of APP metabolism toward the ,-secretase-processing pathway. Moreover, compounds 9,14 showed neuroprotective effects in the 10,20,,M range in the homocysteate (HCA) cortical neuron model of oxidative stress. In parallel, we found that the most neuroprotective compounds caused increased levels of histone acetylation (H4), thus indicating their likely ability to inhibit HDAC activity. As the majority of the compounds studied also show nanomolar binding affinities for PKC, we conclude that it is possible to design, de,novo, agents that combine both PKC-activating properties along with HDAC inhibitory properties. Such agents would be capable of modulating amyloid processing while showing neuroprotection. These findings may offer a new approach to therapies that exhibit disease-modifying effects, as opposed to symptomatic relief, in the treatment of AD. [source] Effect of AlN doping on the growth morphology of SiCCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009N. B. Singh Abstract AlN doped SiC films were deposited on on-axis Si-face 4H-SiC (0001) substrates by the physical vapor transport (PVT) method. Thick film in the range of 20 ,m range was grown and morphology was characterized. Films were grown by physical vapor deposition (PVD) in a vertical geometry in the nitrogen atmosphere. We observed that nucleation occurred in the form of discs and growth occurred in hexagonal geometry. The X-ray studies showed (001) orientation and full width of half maxima (FWHM) was less than 0.1° indicating good crystallinity. We also observed that film deposited on the carbon crucible had long needles with anisotropic growth very similar to that of pure AlN. Some of the needles grew up to sizes of 200 ,m in length and 40 to 50 ,m in width. It is clear that annealing of SiC-AlN powder or high temperature physical vapor deposition produces similar crystal structure for producing AlN-SiC solid solution. SEM studies indicated that facetted hexagons grew on the top of each other and coarsened and merged to form cm size grains on the substrate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Aegyptin displays high-affinity for the von Willebrand factor binding site (RGQOGVMGF) in collagen and inhibits carotid thrombus formation in vivoFEBS JOURNAL, Issue 2 2010Eric Calvo Aegyptin is a 30 kDa mosquito salivary gland protein that binds to collagen and inhibits platelet aggregation. We have studied the biophysical properties of aegyptin and its mechanism of action. Light-scattering plot showed that aegyptin has an elongated monomeric form, which explains the apparent molecular mass of 110 kDa estimated by gel-filtration chromatography. Surface plasmon resonance identified the sequence RGQOGVMGF (where O is hydroxyproline) that mediates collagen interaction with von Willebrand factor (vWF) as a high-affinity binding site for aegyptin, with a KD of approximately 5 nm. Additionally, aegyptin interacts with the linear peptide RGQPGVMGF and heat-denatured collagen, indicating that the triple helix and hydroxyproline are not a prerequisite for binding. However, aegyptin does not interact with scrambled RGQPGVMGF peptide. Aegyptin also recognizes the peptides (GPO)10 and GFOGER with low affinity (,m range), which respectively represent glycoprotein VI and integrin ,2,1 binding sites in collagen. Truncated forms of aegyptin were engineered, and the C-terminus fragment was shown to interact with collagen and to attenuate platelet aggregation. In addition, aegyptin prevents laser-induced carotid thrombus formation in the presence of Rose Bengal in vivo, without significant bleeding in rats. In conclusion, aegyptin interacts with distinct binding sites in collagen, and is useful tool to inhibit platelet,collagen interaction in vitro and in vivo. Structured digital abstract ,,MINT-7299280, MINT-7299290: Collagen (uniprotkb:P02461) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by enzyme linked immunosorbent assay (MI:0411) ,,MINT-7298991, MINT-7299153, MINT-7299208: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by surface plasmon resonance (MI:0107) ,,MINT-7299266: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by fluorescence microscopy (MI:0416) ,,MINT-7299256: Collagen (uniprotkb:P02452) binds (MI:0407) to Aegyptin (uniprotkb:O01949) by solid phase assay (MI:0892) [source] Analysis and comparison of morphological reconstructions of hippocampal field CA1 pyramidal cellsHIPPOCAMPUS, Issue 3 2005José Ambros-Ingerson Abstract Morphological reconstructions have become a routine and valuable tool for neuroscientists. The accuracy of reconstructions is a matter of considerable interest given that they are widely used in computational studies of neural function. Despite their wide usage, comparisons of reconstructions obtained using various methodologies are lacking. We reviewed reconstructions of hippocampal CA1 pyramidal cells from five published studies and found marked differences in some of the most basic measurements. For four of the five studies means of total cell length clustered in the 11,479,13,417-,m range. The remaining study had a significantly larger value for this index at 16,992 ± 5,788 ,m. Surface area means varied more than 4-fold from 16,074 to 67,102 ,m2. Volume means varied more than 8-fold from 3,828 to 30,384 ,m3. Simulated passive input resistance means varied from 38.0 to 172.1 M,, reflecting the variability in cell dimensions. Estimates of the electrotonic length varied from 1.26 to 1.56. In two reconstructions used in previously published studies, simulated somatic excitatory postsynaptic potentials (EPSPs) varied 2,4-fold in amplitude, time to peak and half-width, for synaptic inputs at similar locations. Substantial jitter on the z -axis was identified as one likely source of the discrepancy in total cell length, while substantial differences in diameter measurements across studies, and sometimes within the same study, accounted for the variability in surface area and volume. While some part of the observed variability is surely due to the diversity of CA1 pyramidal cells, our analysis suggests that a substantial portion stemmed from methodological inconsistencies and from technological limitations. Suggestions are made for improving the quality and usefulness of morphological reconstructions. We conclude that reconstructions across studies have substantial variability in measures that are very relevant to neuronal function. Consequently, modelers are advised to use more than just one reconstructed cell in their simulations of neural function. © 2004 Wiley-Liss, Inc. [source] Karakorum,Hindukush,western Himalaya: assessing high-altitude water resourcesHYDROLOGICAL PROCESSES, Issue 12 2005M. Winiger Abstract The high mountains of Central and South Asia provide irrigation water for their adjacent lowlands. The Indus Irrigation Scheme depends on approximately 50% of its runoff originating from snowmelt and glacier melt from the eastern Hindukush, Karakorum and western Himalaya. The Atlas of Pakistan indicates that these mountains gain a total annual rainfall of between 200 and 500 mm, amounts that are generally derived from valley-based stations and not representative for elevated zones. High-altitude snowfall seems to be neglected and is obviously still rather unknown. Estimates derived from accumulation pits runoff above 4000 m range from 1000 mm to more than 3000 mm, depending on the site and time of investigation, as well as on the method applied. To assess the vertical spatio-temporal distribution of total annual precipitation, a combined approach is presented. This approach links in situ measurements of snow depth and water equivalent (10-year time series derived from automatic weather stations at elevations between 1500 and 4700 m a.s.l.), the spatial distribution and period of snow coverage (remotely sensed data and digital elevation models), and the runoff characteristics of streams originating from snow or snow/ice-covered watersheds (modified snowmelt runoff model, including intermediate snowfall and glacier runoff). Based on conservative assumptions, the vertically changing seasonal ratio between liquid and solid precipitation is calculated. Using a combined snow cover and ablation model, total annual amounts of precipitation are derived for different altitudinal zones. Amounts of modelled and measured runoff complement the investigation. Horizontal gradients along the Indus,Gilgit,Hunza transect indicate the varying dominance of seasonal precipitation regimes (monsoonal, Mediterranean and continental disturbances) south of Nanga Parbat, between Nanga Parbat and Batura Wall (=West Karakorum rainfall regime: 1500,1800 mm year,1 at 5000 m) and areas north of Batura (=Central Asian rainfall regime: ,600 mm year,1 at 5000 m). Copyright © 2005 John Wiley & Sons, Ltd. [source] Smooth Continuous Films of Stoichiometric Silicon Carbide from Poly(methylsilyne),ADVANCED MATERIALS, Issue 8 2004W. Pitcher A new synthesis of the silicon-network-backbone polymer poly(methylsilyne) gives a material that is easily converted by pyrolysis to smooth continous films of stoichiometric silicon carbide (see Figure). The films are adherent to the silicon or alumina substrates, and show root mean square roughness of 169,Ĺ over a 500,,m range. Applications in electronics are envisaged. [source] Monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Andreas Greiderer Abstract Monolithic poly(1,2-bis(p -vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p -vinylphenyl)ethane in the presence of inert diluents (porogens) and ,,,,-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 ,m ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5,400 nm and flow-channels in the ,m range. N2 -adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (,20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p -vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for ,-HPLC towards a huge range of analytes of different chemistries and molecular sizes. [source] Effect of Diet Processing Method and Ingredient Substitution on Feed Characteristics and Survival of Larval Walleye, Sander vitreusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2006Frederic T. Barrows Two methods were developed for the production of larval fish diets. The first method, microextrusion marumerization (MEM), has been tested in laboratory feeding trials for many years and produces particles that are palatable and water stable. The second method, particle-assisted rotational agglomeration (PARA), produced diets that have lower density than diets produced by MEM. Each method was used to produce diets in the 250- to 400- and 400- to 700-,m range and compared with a reference diet (Fry Feed Kyowa, [FFK]) for feeding larval walleye in two experiments. The effect of substituting 4% of the fish meal with freeze-dried artemia fines was also investigated. In the first experiment, 30-d survival was greater (P < 0.05) for fish fed a diet produced by PARA without Artemia (49.1.0%) than for fish fed the same diet produced by MEM (27.6%). The addition of Artemia to a diet produced by MEM did not increase survival of larval walleye. Fish fed the reference diet had 24.4% survival. In the second experiment, there was an effect of both processing method and Artemia supplementation, and an interaction of these effects, on survival. Fish fed a diet produced by PARA without Artemia supplementation had 48.4% survival, and fish fed the same diet produced by MEM had only 19.6% survival. Inclusion of 4% freeze-dried Artemia improved (P < 0.04) survival of fish fed MEM particles but not those fed PARA particles. Fish fed FFK had greater weight gain than fish fed other diets in both experiments. Data indicate that the PARA method of diet processing produces smaller, lower density particles than the MEM process and that diets produced by the PARA process support higher survival of larval walleye with low capital and operating costs. [source] Seed Dispersal Distances and Plant Migration Potential in Tropical East AsiaBIOTROPICA, Issue 5 2009Article first published online: 9 MAR 200, Richard T. Corlett ABSTRACT Most predictions of vegetation responses to anthropogenic climate change over the next 100 yr are based on plant physiological tolerances and do not account for the ability of plant species to migrate over the distances required in the time available, or the impact of habitat fragmentation on this ability. This review assesses the maximum routine dispersal distances achievable in tropical East Asia and their vulnerability to human impacts. Estimates for various plant,vector combinations range from < 10 m, for species dispersed by ants or mechanical means, to > 10 km for some species dispersed by wind (tiny seeds), water, fruit pigeons, large fruit bats (tiny seeds), elephants, rhinoceroses, and people. Most plant species probably have maximum dispersal distances in the 100,1000 m range, but the widespread, canopy-dominant Dipterocarpaceae and Fagaceae are normally dispersed < 100 m. Large fruit bats and fruit pigeons are particularly important for long-distance dispersal in fragmented landscapes and should be protected from hunting. The maximum seed dispersal distances estimated in this study are potentially sufficient for many plant species to track temperature changes in steep topography, but are far too small for a significant role in mitigating climate change impacts in the lowlands, where temperature and rainfall gradients are much more shallow. [source] Histomorphometric analysis of the osseointegration of four different implant surfaces in the femoral epiphyses of rabbitsCLINICAL ORAL IMPLANTS RESEARCH, Issue 11 2008Laurent Le Guehennec Abstract Objectives: The surface properties of titanium dental implants are key parameters for rapid and intimate bone,implant contact. The osseointegration of four implant surfaces was studied in the femoral epiphyses of rabbits. Material and methods: Titanium implants were either grit-blasted with alumina or biphasic calcium phosphate (BCP) ceramic particles, coated with a thin octacalcium phosphate (OCP) layer, or prepared by large-grit sand blasting and acid-etched (SLA). After 2 and 8 weeks of implantation, the bone-implant contact and bone growth inside the chambers were compared. Scanning electron microscopy (SEM) and profilometry showed distinct microtopographies. Results: The alumina-Ti, BCP-Ti and OCP-Ti groups had similar average surface roughness in the 1,2 ,m range whereas the SLA surface was significantly higher with a roughness averaging 4.5 ,m. Concerning the osseointegration, the study demonstrated a significantly greater bone-to-implant contact for both the SLA and OCP-Ti surfaces as compared with the grit-blasted surfaces, alumina- and BCP-Ti at both 2 and 8 weeks of healing. Conclusion: In this animal model, a biomimetic calcium phosphate coating gave similar osseointegration to the SLA surface. This biomimetic coating method may enhance the apposition of bone onto titanium dental implants. [source] | ||||||||||||||||