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A series of ligands derived from the bis‐2‐pyridinylmethylamine structure, which bear either additional hydroxyl or aromatic amino groups, were prepared and their ZnIIcomplexes were studied as catalysts for the cleavage of bis‐p‐nitrophenyl phosphate (BNP) and 2‐hydroxypropyl‐p‐nitrophenyl phosphate (HPNP) diesters. A comparative kinetic study indicated that the insertion of organic groups, capable of acting as nucleophiles or as hydrogen‐bond donors, substantially increases the hydrolytic activity of the metal complex. Dissection of the effects of the individual groups revealed that the increase in reactivity can reach up to three orders of magnitude. The improved efficiency of the systems studied, combined with the benefits resulting from the low pKavalue of the active nucleophile, result in an acceleration of the BNP cleavage at pH 7 of six orders of magnitude. The pH‐dependent reactivity profiles follow a bell‐shaped curve and the maximum reactivity is observed at pH 9. The mechanism of the reactions and the structure of the complexes were investigated in detail by means of kinetic analysis, NMR spectroscopy experiments, and theoretical calculations. The reactivity of the complexes that cleave HPNP closely resembles the reactivity observed for BNP, but the accelerations achieved are lower as a result of different reaction mechanisms.

Silica nanoparticles (about 15 nm diameters), which contain a derivative of 6‐methoxy‐8‐(p‐toluensulfonamido)‐quinoline (TSQ) as a ZnIIfluorescent probe covalently linked to the silica network, were prepared and studied as ZnIIfluorescent chemosensors. The systems selectively detect ZnIIions in water rich solutions with a submicromolar sensitivity: 0.13 μMconcentrations of ZnIIcan be measured with the only interference of CuIIand CdIIions. Compared with free TSQ, the nanoparticles based systems have the advantage that they can be employed in aqueous solutions without aggregation problems while at the same time, they maintain a similar ZnIIaffinity and sensing ability. Addition of a second, substrate insensitive, fluorophore to the particles leads to the realization of a ratiometric sensor.

We present here the study of the photophysical properties of new dye-doped silica nanoparticles (DDNs) bearing dansyl fluorescent derivatives covalently linked to the silica matrix. The described experimental evidences show how the different location of the chromophores induces great changes in their photophysical behavior, suggesting that fluorophores located near the surface of the nanoparticles have a very different behavior with respect to the internal molecules. These latter ones, in fact, are shielded from the solvent and have a strong blue emission, while those at the periphery interact with the solvent and show a weaker red-shifted emission. As a consequence, the fluorescence properties of these nanoparticles are an average between the characteristics of the two different families of dyes. The relative amount of fluorophores located in the two compartments can be controlled simply by changing the size since, from our results, the thickness of the solvent permeable layer is not relevantly affected by the diameter of the nanoparticles. It is noteworthy that the fluorophores located in the outer shell exhibit very peculiar features:  they are sensitive and interact with small molecules such as solvent molecules but, at the same time, they are not accessible to big receptor species such as -cyclodextrins. Such results indicate that most of the solvent-sensitive dansyl moieties are located within pores large enough to only accommodate solvent but not big molecules as cyclodextrins, giving precious insight on the morphology of the nanoparticles.

The postgenome era has provided resources to link disease phenotypes to the genomic sequence, i.e., creating a disease “phenome.” Our detailed characterization of the sequenced BN rat strain (BN/NHsdMcwi) provides the first concerted effort in creating a direct link between a sequenced genome and its resulting biology. For the BN sequence to be of broad value to investigators, these measures need to be put into the context of the spectrum of the laboratory rats, so that their physiology can be benchmarked against the sequenced BN. As a major step in generating a comprehensive cardiovascular and pulmonary disease phenome, we measured 281 traits related to diseases of the heart, lung, and blood (http://pga.mcw.edu) in the sequenced BN. We compared these data with those of the same traits measured across multiple genetic backgrounds, both genders, and differing environments. We show that no single strain, inbred or outbred, can be considered a physiological control strain; what is normal depends on what trait is being measured and the strains' genome backgrounds. We find vast differences between the genders, also dependent on genome background. By combining the values across all strains studied, we generated a “population” mean and normal range of values for each of these traits, which are more genetically representative than the measured values in any single inbred or outbred strain. These data provide a baseline for physiological comparison of traits related to cardiovascular, lung, blood, and renal function in the sequenced BN rats relative to the major strains of rats studied in biomedical research.

Self‐assembling and self‐organizing methodologies are powerful tools for the “bottom‐up” approach for the realization of complex structure with functional properties. Recently, this concept has been extended to the design of fluorescent chemosensors providing new exciting potentialities for the development of innovative sensing systems. This Concept Article deals mainly with this new approach and discusses its evolution, applications, and limitations.

The broad goal of physiological genomics research is to link genes to their functions using appropriate experimental and computational techniques. Modern genomics experiments enable the generation of vast quantities of data, and interpretation of this data requires the integration of information derived from many diverse sources. Computational biology and bioinformatics offer the ability to manage and channel this information torrent. The Rat Genome Database (RGD; http://rgd.mcw.edu) has developed computational tools and strategies specifically supporting the goal of linking genes to their functional roles in rat and, using comparative genomics, to human and mouse. We present an overview of the database with a focus on these unique computational tools and describe strategies for the use of these resources in the area of physiological genomics.

There is great interest in the self-organization of the proper subunits as a new strategy for the realization of fluorescent chemosensors. In this article, it is shown that commercially available fluorescent dyes, functionalized with triethoxysilane moieties, can be converted into fluorescent chemosensors by simple inclusion into silica nanostructures. Dye-doped silica nanoparticles and thin films detect Cu(II) ions in the micromolar range by the quenching of fluorescence emission. The different response toward Zn(II), Ni(II), and Co(II) metal ions was also investigated and is reported. The self-organization of the silica structures leads, at the same time, to the formation of metal ion binding sites as well as to the linking of a fluorescent reporter in their proximity. Structural features of the materials, particularly particle size and network porosity, strongly affect their ability to act as fluorescent sensors.

The heterogeneous oxidation of various alcohols with oxygen catalysed by TPAP-doped ormosils in scCO2 at 75 °C and 22.0 4;MPa has been studied in detail. Sol-gel segregation of TPAP into the inner porosity of an organically modified silica (ormosil) xerogel along with the use of a reaction medium which does not dissolve the catalyst, prevents aggregation of oxidation-inactive ruthenium derivatives without the need of chemical tethering. Thus, at least 140 TONs may be obtained in the oxidation of primary alcohols with the formation of aldehydes as sole reaction products. Investigation of the oxidation mechanism shows that the catalytic process exhibits a first-order dependence on the amount of catalyst, a fractional order on the alcohol concentration and a negative order for oxygen pressures higher than 0.2 4;bar. Evidence is presented for an associative oxidation mechanism simultaneously involving TPAP, organic substrate and oxygen.

Supercritical carbon dioxide is ideally suited as reaction medium for catalytic oxidations of organic substrates, and it may be exploited as one of the most promising strategies to realize some fundamental chemical transformations under environmentally benign conditions. The use of supercritical carbon dioxide as solvent for unselective hydrocarbons auto-oxidations is extensively described in the literature. Conversely, only a limited number of reports deal with selective oxidations carried out by molecular oxygen or by other primary oxidants such as hydrogen peroxide, alkyl hydroperoxides, monopersulfate, etc. In this paper recent developments in selective catalytic oxidations are reviewed and particular attention is devoted to those processes in which a metal derivative, capable of selectively oxidizing various substrates, is formed by action of a terminal oxidant such as oxygen or an organic or inorganic peroxide.

The self-organization of the proper subunits of a fluorescence chemosensor on the surface of silica nanoparticles allows the easy design and realization of new effective sensing systems. Commercially available silica particles 20 nm diameter were functionalized with triethoxysilane derivatives of selective Cuii ligands and fluorescent dyes. Grafting of the sensor components to the particle surface ensures the spatial proximity between the sensor components and, as a consequence, binding of Cuii ions by the ligand subunits leads to quenching of the fluorescent units emission. In 9 : 1 DMSO–water solution, the coated silica nanoparticles CSNs selectively detect copper ions down to nanomolar concentrations. The operative range of the sensors can be tuned either by switching the ligand units or by modification of the components ratio. Sensors with the desired photophysical properties can be easily prepared by using different fluorescent dyes. Moreover, the organization of the network of sensor components gives rise to cooperative and collective effects: on one hand, the ligand subunits bound to the particle surfaces cooperate to form multivalent binding sites with an increased affinity for the Cuii ions; on the other hand, binding of a single metal ion leads to the quenching of several fluorescent groups producing a remarkable signal amplification.

The development of synthetic agents able to hydrolytically cleave DNA with high efficiency and selectivity is a fascinating challenge that will show the way to obtaining artificial nucleases able to compete with the natural enzymes. This Feature Articlehighlights the progress reported toward the realization of synthetic nucleases with particular attention to the strategies that can be pursued to improve efficiency and sequence selectivity.

We describe the theoretical basis for a peptide identification method wherein peptides are represented as vectors based on their amino acid composition and grouped into clusters. Unknown peptides are identified by finding the database cluster and peptide entries with the shortest Euclidian distance. We demonstrate that the amino acid composition of peptides is virtually as informative as the sequence and allows rapid peptide identification more accurately than peptide mass alone. Keywords: proteomics • protein identification • bioinformatics • algorithm • proteins • peptides • mass spectrometry

The heterogeneous oxidation of cyclooctene with H2O2 catalyzed by Mnporphyrins embedded in polydimethylsiloxane (PDMS) and organically modified silicates (ORMOSILs), in the presence of hexafluoroacetone hydrate (HFAH) as cocatalyst, has been studied in supercritical carbon dioxide (scCO2) at 40°C and 20 MPa. Complete olefin conversion may be obtained with the formation of cyclooctene oxide as sole product, employing molar ratios of Mn-porphyrin/Substrate/H2O2 of 1:400:2000.

Two dimetallic ligands 2 and 3 for transition metal ions were obtained by connecting two all-cis-2,4,6-triamino-cyclohexane-1,3,5-triol (TACI, 1) subunits via 1,3- or 1,4-xylyl linkers. Their dimetallic Cu^II and Zn^II complexes were investigated as catalysts for the cleavage of the phosphate diesters 2,4-dinitrophenyl ethyl phosphate (DNPEP) and 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) and the triester 2,4-dinitrophenyl diethyl phosphate (DNPDEP). The results of a comparative kinetic study using the monometallic complexes of TACI as a reference indicate that the Cu^II complexes of 2 and 3 are virtually inert; this finding is ascribed to the formation of intra-complex μ-hydroxo bridges that prevent the required interactions with the substrate. On the other hand, the dimetallic Zn^II complexes produce remarkable accelerations, particularly in the case of the HPNP transesterification. The dimetallic systems are more efficient than the TACI·Zn^II complex in promoting the hydrolysis of HPNP at pH values close to neutrality (7.0−7.8). In this case, the effects of cooperativity between the two metal centers were highlighted in a detailed kinetic study; the catalytic efficiency seems to be related to the stronger binding of the substrate to the dimetallic Zn^II complexes. Additionally, in this case, although to a much lesser extent than in the case of the Cu^II counterparts, the formation of μ-hydroxo bridges apparently hampers the catalytic efficiency, as indicated also by the observation that the activity of the dimetallic complexes increases as the distance between the two metal centers increases, which, thus, thwarts the formation of intermetallic bridges. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Genetic linkage analyses in human populations have traditionally combined male and female progeny for determination of quantitative trait loci (QTL). In contrast, most rodent studies have focused primarily on males. This study represents an extensive female-specific linkage analysis in which 236 neuroendocrine, renal, and cardiovascular traits related to arterial pressure (BP) were determined in 99 female F2 rats derived from a cross of Dahl salt-sensitive SS/JrHsdMcwi (SS) and Brown Norway normotensive BN/SsNHsdMcwi (BN) rats. We identified 126 QTL for 96 traits on 19 of the 20 autosomal chromosomes of the female progeny. Four chromosomes (3, 6, 7, and 11) were identified as especially important in regulation of arterial pressure and renal function, since aggregates of 8–11 QTL mapped together on these chromosomes. BP QTL in this female population differed considerably from those previously found in male, other female, or mixed sex population linkage analysis studies using SS rats. Kidney weight divided by body weight was identified as an intermediate phenotype that mapped to the same region of the genome as resting diastolic blood pressure and was correlated with that same BP phenotype. Seven other phenotypes were considered as “potential intermediate phenotypes, ” which mapped to the same region of the genome as a BP QTL but were not correlated with BP. These included renal vascular responses to ANG II and ACh and indices of baroreceptor responsiveness. Secondary traits were also identified that were likely to be consequences of hypertension (correlated with BP but not mapped to a BP QTL). Seven such traits were found, notably heart rate, plasma cholesterol, and renal glomerular injury. The development of a female rat systems biology map of cardiovascular function represents the first attempt to prioritize those regions of the genome important for development of hypertension and end organ damage in female rats.

The photooxidation of various olefins in homogeneous solution under an oxygen atmosphere, by use of visible light, a dye sensitizer, and an oxygen-transfer catalyst, has been investigated. The oxygen transfer from molecular oxygen to olefin involves the following steps: i) photoinduced singlet-oxygen formation, ii) alkyl hydroperoxide formation through the ene reaction, iii) the intermediacy of a reactive molybdenum peroxide, and iv) olefin epoxidation of the remaining substrate or of a second olefin. Among the various sensitizers and catalysts tested, the electron-deficient free base porphyrin 5,10,15,20-tetrakis(2',6'-dichlorophenyl)-β-octabromoporphyrin and hexacarbonylmolybdenum showed the best performances in terms of robustness and activity. Under suitable conditions, complete olefin conversion may be obtained by adoption of molar ratios of sensitizer/catalyst/substrate of 1:50:2000, with the formation of the corresponding epoxide in up to 38% yield, which corresponds to 77% of the theoretical maximum. Quite interestingly, olefins reluctant to undergo ene reactions may be epoxidized in the presence of a second sacrificial olefin, yielding the corresponding epoxides with up to 80% total selectivity. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Three copies of peptide sequences from the peptaibol family, known to affect the permeability of the lipid bilayer of membranes, were connected to tris(2-aminoethyl)amine (TREN), a tripodal metal ion ligand, to prepare functional peptides capable of modifying the permeability of liposomal membranes. Some of the resulting tripodal polypeptide derivatives are very effective in promoting carboxyfluorescein (CF) leakage from CF-loaded unilamellar vesicles composed of a 70:30 phosphatidylcholine/cholesterol blend. The activity of these novel compounds was shown to be tunable upon metal ion coordination of the TREN subunit; the tripodal apopeptide was far more effective than its Zn^II complex. Leakage experiments showed that a minimum number of five amino acids per peptide chain is required to form active systems. A mechanism is proposed in which the Zn^II ion changes the conformation of the template from extended to globular and thus acts as an allosteric regulator of the activity of the systems. Molecular modeling studies indicate that when the three peptide chains are connected to the template in the extended conformation, the resulting tripodal polypeptide is able to span across the membrane, thus allowing the formation of permeable channels made of a cluster of molecules. The same change of conformation induces, to some extent, fusion of the membranes of different liposomes. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2111/2002/f3765_s.pdf or from the author.

The interaction of lipoic acid with β-cyclodextrin (β-CD) has been studied by capillary electrophoresis in aqueous phosphate buffer (20 mM, pH = 9.0) at 20 °C. The results allowed us to detect the formation of an inclusion complex with a 1:1 lipoic acid/β-CD stoichiometry and an association constant of 1645 M⁻¹. The geometry of the inclusion complex in D2O was investigated by means of 2D-ROESY (Rotating-frame Overhauser Enhancement Spectroscopy) NMR experiments, which showed the occurrence of a bimodal complexation of lipoic acid inside the β-CD cavity. Semi-empirical calculations using the PM3 method show that the orientations of the included lipoic acid are very close in energy, thus confirming the experimental observations. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

The fluorescence chemosensor ATMCA has been realised by appending an anthrylmethyl group to an amino nitrogen of TMCA (2,4,6-triamino-1,3,5-trimethoxycyclohexane), a tripodal ligand selective for divalent first-row transition metal ions in water. The ATMCA ligand can act as a versatile sensor for Zn^II and Cu^II ions. Its sensing ability can be switched by simply tuning the operating conditions. At pH 5, ATMCA detects copper(II) ions in aqueous solutions by the complexation-induced quenching of the anthracene emission. Metal ion concentrations <1 μM can be readily detected and very little interference is exerted by other metal ions. At pH 7, ATMCA signals the presence of Zn^II ions at concentrations <1 μM by a complexation-induced enhancement of the fluorescence. Again the sensor is selective for Zn^II over several divalent metal ions, with the exception of Cu^II, Co^II and Hg^II. Most interestingly, the [Zn^II(atmca)]²⁺ complex can act as a fluorescence sensor for specific organic species, notably selected dicarboxylic acids and nucleotides, by the formation of ternary ligand/zinc/substrate complexes. The oxalate anion is detected in concentrations <0.1 mM; however, no effects on the system's fluorescence is observed in the presence of monocarboxylic acids and long-chain dicarboxylic acids. Among the nucleotides, those containing an imide or amide function are readily detected and an unprecedented high sensitivity for guanine derivatives allows the determination of this nucleotide for 0.05–0.5 mM solutions. Moreover, [Zn^II(atmca)]²⁺ is a very effective and selective sensor in the case of vitamin B13 (orotic acid) in sub-micromolar concentrations. The operative features of the systems investigated are also clearly suitable for intracellular analyses. The factors at the source of organic substrate recognition, here briefly discussed, are of paramount importance for further developments in the applicability of these sensing systems. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2111/2002/f3321_s.pdf or from the author.

The heterogeneous oxidation of cyclooctene with hydrogen peroxide catalyzed by manganese 5,10,15,20-tetrakis(2',6'-dichlorophenyl)porphyrinate, in the presence of hexafluoroacetone hydrate as co-catalyst, has been studied in supercritical carbon dioxide, at 40 °C and 20 MPa. Under proper conditions, a complete olefin conversion may be obtained with the formation of cyclooctene oxide as the sole product. Fixation by hexafluoroacetone into its perhydrate derivatives provides a useful system to solubilize hydrogen peroxide in supercritical carbon dioxide, and to hamper catalyst bleaching and oxidant decomposition. Moreover, in the presence of both manganese-porphyrin and hexafluoroacetone, the reaction rates are enhanced. Among the factors that may increase yields and rate of conversion, the use of a Teflon-coated steel reactor rather than an uncoated one proved to be quite relevant, thus indicating the occurrence of a parasite radical decomposition of hydrogen peroxide promoted by steel reactor walls.

The self-assembling of the proper subunits of fluorescence chemosensors within surfactant aggregates in water allows the easy design, realization, and testing of new effective sensing systems. It was shown that a proper ligand and a fluorescent dye, once transferred from bulk water into an inert surfactant aggregate, are kept in such a close proximity that communication between the binding site and the signaling unit effectively occurs, thus avoiding the need for a covalent connection between the sensor's two units. To further simplify the sensing system and get rid of the inert surfactant which somehow implies the dilution of the sensor's active components in the aggregate, we have synthesized a series of lipophilic ligands for Cu(II) based on dipeptides GlyLys and GlyGlu functionalized with n-alkyl chains of different lengths at the N-terminus. These ligands are soluble in water and can form homoaggregates in the absence and in the presence of Cu(II) ions. Lipophilic fluorophores, like 8-anilino-naphthalensulfonic acid or Rhodamine 6G, are effectively bound into the aggregate pseudophase, and the binding of Cu(II) ions to the dipeptide units causes a strong fluorescence quenching. The sensor system is very sensitive to Cu(II) (concentrations in the submicromolar range are detected), is promptly reversible, and no interference is observed due to the presence of many metal ions. The sensitivity of the systems improves by decreasing the ligand concentration and (up to a point) the ligand's cmc.

Animal models have been used primarily as surrogates for humans, having similar disease-based phenotypes. Genomic organization also tends to be conserved between species, leading to the generation of comparative genome maps. The emergence of radiation hybrid (RH) maps, coupled with the large numbers of available Expressed Sequence Tags (ESTs), has revolutionized the way comparative maps can be built. We used publicly available rat, mouse, and human data to identify genes and ESTs with interspecies sequence identity (homology), identified their UniGene relationships, and incorporated their RH map positions to build integrated comparative maps with >2100 homologous UniGenes mapped in more than one species (approximately 6% of all mammalian genes). The generation of these maps is iterative and labor intensive; therefore, we developed a series of computer tools (not described here) based on our algorithm that identifies anchors between species and produces printable and on-line clickable comparative maps that link to a wide variety of useful tools and databases. The maps were constructed using sequence-based comparisons, thus creating "hooks" for further sequence-based annotation of human, mouse, and rat sequences. Currently, this map enables investigators to link the physiology of the rat with the genetics of the mouse and the clinical significance of the human.

The hydrolytic reactivity of ligands featuring a 6-alkylaminomethylpyridine, 1, or an N-alkylethylenediamine, 2, as chelating subunits, in the presence of Cu(II), has been investigated in AOT/H2O/isooctane reversed micelles. The substrates of choice were the p-nitrophenyl esters of picolinic acid (PNPP), of acetic acid (PNPA), and of diphenylphosphoric acid (DPPNPP). In the presence of Cu(II) complexes of hydroxy-functionalized ligands, such as 1a or 1b, the cleavage of PNPP is a million-fold faster than in the absence of Cu(II) and any ligand, the most effective stoichiometry being 1:1. By converse, the rate effects are rather modest using ligands 1c and 2, devoid of the hydroxy function. The cleavage of PNPA and DPPNPP is only slightly accelerated using all kind of ligands investigated. The high reactivity observed using 1a and 1b and PNPP accords with the mode of action established in aqueous micelles. This involves formation of a ternary complex (ligand/Cu(II)/substrate), pseudointramolecular attack of the (deprotonated) hydroxyl on the ester carbonyl to give a transesterification intermediate, and metal ion promoted hydrolysis of such intermediate. The kinetic response of the reversed micelles is in many ways quite different from that of analogous aqueous aggregates previously investigated. Peculiar features include the apparent insensitivity to relevant variables, such as the pH of added water, the w0 (the H2O/AOT ratio) value, and the lipophilic or hydrophilic character of the ligand. Clean burst kinetics using 1a·Cu(II) and excess PNPP were obtained but indicate a disappointingly low turnover rate. These and other aspects are discussed, also with reference to the behavior of aqueous micelles, and an attempt is made to describe the rather puzzling nature of interface and core of the reversed aggregates.

We report the establishment of a hybridization-based marker system for the rat genome based on the PCR amplification of interspersed repetitive sequences (IRS). Overall, 351 IRS markers were mapped within the rat genome. The IRS marker panel consists of 210 nonpolymorphic and 141 polymorphic markers that were screened for presence/absence polymorphism patterns in 38 different rat strains and substrains that are commonly used in biomedical research. The IRS marker panel was demonstrated to be useful for rapid genome screening in experimental rat crosses and high-throughput characterization of large-insert genomic library clones. Information on corresponding YAC clones is made available for this IRS marker set distributed over the whole rat genome. The two existing rat radiation hybrid maps were integrated by placing the IRS markers in both maps. The genetic and physical mapping data presented provide substantial information for ongoing positional cloning projects in the rat.

AbstractThe hydrolytic activity of the 1,3,5-triaminocycloxexane derivatives TACH, TACI and TMCA complexed to Zn(II) and Cu(II) towards a model phosphoric ester and plasmid DNA has been evaluated by means of spectroscopic and gel-electrophoresis techniques. At conditions close to physiological, a prominent cleavage effect mediated by the nature of the ligand and metal ion was generally observed. TACI complexes are the most active in relaxing supercoiled DNA, the effect being explained by the affinity of the hydroxylated ligand for the nucleic acid. As indicated by the dependence of cleavage efficiency upon pH, Zn(II)-complexes act by a purely hydrolytic mechanism. In the case of Cu(II)-complexes, although hydrolysis should be prominent, involvement of an oxidative pathway cannot be completely ruled out.

Cowley, A. W., Jr., Monika Stoll, Andrew S. Greene, Mary L. Kaldunski, Richard J. Roman, Peter J. Tonellato, Nicholas J. Schork, Pierre Dumas, and Howard J. Jacob.Genetically defined risk of salt sensitivity in an intercross of Brown Norway and Dahl S rats. Physiol Genomics2: 107–115, 2000.—A genetic segregation analysis was performed to identify genes that cosegregate with arterial blood pressure traits reflective of salt sensitivity. A population of 113 F2 male rats was derived from an intercross of inbred SS/JrHsd/Mcw (Dahl salt-sensitive) and BN/SsN/Mcw (Brown Norway) rats. Rats were maintained on an 8% salt diet from the age of 9 to 13 wk, and arterial pressure was measured for 3 h daily during the 4th wk of high salt intake in unanesthetized rats using implanted arterial catheters. At the end of the 3rd day of high-salt pressure recordings, the arterial pressure response to salt depletion was determined 1.5 days following treatment with Lasix and a low-sodium (0.4%) diet. A genome-wide scan using 265 polymorphic simple sequence length polymorphism (SSLP) markers found that seven arterial pressure phenotypes determined at different times and circumstances, and representing two distinct indexes of salt sensitivity, mapped to the same region of rat chromosome 18. The trait of salt sensitivity was strongly influenced by the presence of SS alleles in this region of chromosome 18, and those rats which were homozygote SS/SS exhibited a significantly greater reduction of mean arterial pressure following sodium depletion (29 ± 2 mmHg) than homozygote BN/BN (17 ± 3 mmHg) or heterozygotic (22 ± 2 mmHg) rats. This region of rat chromosome 18 corresponds to the long arm of human chromosome 5 and a region of human chromosome 18 that has been linked to hypertension in humans. Given the unlikely chance of these different blood pressure traits mapping to the same region, we believe these data provide evidence that this region of rat chromosome 18 plays an important role in salt-induced hypertension.

A kinetic study of the reactivity in the cleavage of p-nitrophenyl acetate of a series of 2-pyridineoximes, 1-4, and their complexes with Ni^II, Zn^II and Cu^II is reported. Complexation of the oximic ligands leads to a remarkable increase in the acidity of the oximic group, following the order Cu^II > Ni^II > Zn^II. The oximates of free ligands and their metal complexes, being α-nucleophiles, are quite effective in promoting the cleavage of PNPA. However, the reactivity, as defined by the second-order rate constants, is not predictably related to the acidity of the oximic function. The corresponding Brønsted plot shows a linear behaviour up to a pKa value of ca. 8, above which the reactivity of the uncomplexed oximic functions levels off to a limiting value. In the case of the metal ion complexes, a large effect of the ligand structure on the reactivity was observed. As a consequence, complexes of appropriate ligands and metal ions show a reactivity that exceeds the apparent limiting one of the oximates. The origin of such effects and their possible implications in the development of new reactivators of phosphorylated acetylcholinesterase are discussed.

Ligands featuring a 6-alkylaminomethyl-2-pyridinealdoxime moiety (alkyl = CH3, 2a, or n-C12H25, 2b) have been synthesized, and the reactivity of their Ni(II) and Zn(II) complexes in the cleavage of p-nitrophenyl acetate (PNPA) and hexanoate (PNPH) has been investigated in the absence (2a) or in the presence (2b) of CTABr micelles. The micellar complexes are effective in promoting the cleavage of the substrate with accelerations strongly dependent on the pH, being larger in moderately acidic than in neutral solutions. At pH 5 the Ni(II)/2b/CTABr micelles increase the rate of the cleavage of PNPH by 3 orders of magnitude as compared to CTABr only and by 2 orders of magnitude as compared to the nonmicellar complex of 2a. Moreover the system is truly catalytic with a turnover rate approaching that of the cleavage. Analysis of the second-order rate constants allows the conclusions that the increased reactivity of the micellar system is due to concentration and local-pH effects and not to the activation of the nucleophile. A comparison of the reactivity of the systems made of complexes of 2 with that of the analogues of the 2-pyridineketoxime ligands (1) previously investigated indicates that the insertion of the new chelating atom in the binding subsite, on one hand, increases the formation constant of the metal ion complexes and, on the other hand, decreases the nucleophilicity of the complexed oximate ion. The balance of these two effects, in the operative conditions, favors ligands 2 over ligands 1 due to the higher fraction of complexed oximes.

Simply by mixing in water, a liphophilic dipeptide (L), a surfactant (S), and a fluorophore (F) self-assemble to give a sensor able to detect Cu^II ions (see scheme). Despite the ease of construction, the sensor displays high selectivity and a low detection limit for the target ion. This new modular approach to sensing devices allows easy variations of the components, making optimization of the system very simple and fast.

A series of 2-pyridineketoximes with paraffinic chains of different lengths (CH3, 1a; C8H17, 1b; C13H27, 1c) has been synthesized, and their complexes with Cu(II), Co(II), Zn(II), and Ni(II) have been investigated in the cleavage of p-nitrophenyl esters of carboxylic and phosphoric acids in water (1a) or in comicelles with CTABr (1b,c). While the Co(II) and Cu(II) complexes are ineffective in promoting the cleavage of acetate (PNPA) and hexanoate (PNPH) esters, the Zn(II) and especially the Ni(II) complexes strongly accelerate the cleavage of such substrates. With the latter metal ion, the effective species is a complex with a 2:1 ligand/metal ion stoichiometry and a pKa of the oximic hydroxyl of approximately 5 and 3.7 in the absence and in the presence of CTABr, respectively. Strong evidence has been obtained concerning the mode of action which involves nucleophilic attack of the oximate function on the carbonyl carbon of the ester to give, as transient intermediate, the acylated oxime; its Ni(II)-mediated hydrolysis by water has also been investigated to better define the whole catalytic cycle. The system displays its highest efficiency at low pH values and in comicelles of CTABr:  in the presence of 1b/Ni(II)/CTABr at pH 4 the observed rate enhancements are of over 5 orders of magnitude in the cleavage of PNPH and the system is truly catalytic with a sizable turnover rate. In comparison with the high reactivity toward carboxylic esters, the metal ion complexes of the ketoximes investigated are surprisingly ineffective in promoting the cleavage of p-nitrophenyl esters of diphenylphosphoric acid (PNPDPP).