Free Analogues Research Articles

QSAR of distribution coefficients for Pu(NO3)62- complexes using molecular mechanics

Computer-aided modeling has been very successful in the design of chelating ligands for the formation of selective metal complexes. We report herein preliminary efforts to extend the principles developed for ion-specific chelating ligands to the weaker, more diffuse electrostatic interactions between complex anions and dicationic sites of anion-exchange resins. We present formal- and partial-charge methodologies for determining calculated electrostatic affinity between plutonium(IV) hexanitrato dianions and free analogues of dicationic anion-exchange sites. Both approaches correlate well with empirically-determined distribution coefficients for our bifunctional pyridinium-based resins (0.65<r 2<0.98). This quantitative structure activity relationship (QSAR) will be useful in the determination of which structural modifications within a select series of bifunctional resins are most likely to be advantageous. Ultimately, we hope to refine this methodology to allow the a priori determination of ion-exchange behavior for a broad class of materials.

Le Groupe Quantique Compact Libre U(n)

The free analogues of U(n) in Woronowicz' theory [Wo2] are the compact matrix quantum groups introduced by Wang and Van Daele. We classify here their irreducible representations. Their fusion rules turn to be related to the combinatorics of Voiculescu's circular variable. If we find an embedding , where A o (F) is the deformation of SU(2) studied in [B2]. We use the representation theory and Powers' method for showing that the reduced algebras A u (F) red are simple, with at most one trace.

Free quasi-free states

To a real Hilbert space and a one-parameter group of orthogonal transformations we associate a C∗-algebra which admits a free quasi-free state. This construction is a freeprobability analog of the construction of quasi-free states on the CAR and CCR algebras. We show that under certain conditions, our C∗-algebras are simple, and the free quasi-free states are unique. The corresponding von Neumann algebras obtained via the GNS construction are free analogs of the Araki-Woods factors. Such von Neumann algebras can be decomposed into free products of other von Neumann algebras. For non-trivial one-parameter groups, these von Neumann algebras are type III factors. In the case the one-parameter group is nontrivial and almost-periodic, we show that Connes’ Sd invariant completely classifies these algebras.

Unesterified long chain fatty acids inhibit the binding of single chain urokinase to the urokinase receptor.

The interaction of single chain urokinase with its receptor accelerates plasminogen activator activity on cell surfaces and induces intracellular signalling in several cell types. To date, no physiologic inhibitor of this binding has been identified. We report that the binding of scuPA to its cellular receptor is inhibited by long chain fatty acids such as oleic acid (C18, delta 9) at physiological plasma concentrations. Inhibition of single chain urokinase binding to human trophoblastic cells by long chain fatty acids was dose-dependent and saturable. Fifty percent of the binding was inhibited at an oleic acid concentration of 27 microM, while inhibition was maximal (75%) at 150 microM oleic acid. The inhibitory potency of oleic acid was unaffected by fatty acid free albumin or human plasma. Inhibition of single chain urokinase binding by free fatty acid analogues was critically dependent on chain length (> C14 required for inhibition) and was proportional to the extent of unsaturation. Only the fraction of specific scuPA binding to trophoblasts that was dependent on uPAR was susceptible to inhibition by oleic acid, while binding of scuPA to vitronectin, thombospondin, and the alpha 2-macroglobulin receptor/low-density lipoprotein-related receptor was not. [3H]Oleic acid bound specifically to recombinant soluble uPAR in a 1:1 molar ratio in the presence or absence of plasma and totally blocked its specific binding to a cell line expressing glycosyl phosphatidylinositol-linked single chain urokinase. These results indicate that oleic acid and other unsaturated long chain free fatty acids may serve as physiologic regulators of proteolytic events and intracellular signalling that depend upon the interaction of urokinase with its receptor.

Regulation of Internal Ca 2+ by Chilled Bull and Boar Spermatozoa

Intracellular Ca 2+ in ejaculated spermatozoa from five bulls and five boars was determined with indo-1,AM in Ca 2+ -free medium. Aliquots of each ejaculate were then wrapped and held either on ice or at 25°C for 20 min. At this time all samples were returned to 25°C, either Ca 2+ -free medium or medium containing 1 m M Ca 2+ was added, and intracellular Ca 2+ was determined for an additional 120 min. Before and immediately after chilling, internal Ca 2+ in bull spermatozoa did not differ. However, exogenous Ca 2+ caused both control and chilled bovine spermatozoa to accumulate Ca 2+ over the subsequent 120 min ( P < 0.01) with the control spermatozoal rate of Ca 2+ intake being faster than that of the chilled (slopes, 29.531 vs 8.374 relative Ca 2+ units/min; least squares means (lsmean) × 104 ± 1.901 (pooled SE); P < 0.01). Viability of all spermatozoa was reduced after Ca 2+ exposure, and the acrosomal morphology of chilled cells was adversely affected by Ca 2+. For boar spermatozoa, chilling caused an immediate increase in internal Ca 2+, confirming the greater sensitivity of boar spermatozoa to low temperatures. The presence of exogenous Ca 2+ caused greater Ca 2+ uptake by both control and chilled porcine cells relative to their Ca 2+ -free analogues (0.939 vs 0.764 and 1.015 vs 0.836 Ca 2+ units; lsmean ± 0.166 (pooled SE); P < 0.01 for control and chilled boar spermatozoa with and without Ca 2+ at 150 min). Control spermatozoa, however, accumulated Ca 2+ ( P < 0.01) at a much greater rate (slope, 20.964 ± 2.73 relative Ca 2+ units × 10 4/min; P ⩽ 0.001) than chilled cells, which only tended ( P = 0.08) to accumulate Ca 2+ (slope, 4.782 ± 2.73 relative Ca 2+ units × 10 4/min). This study suggests that chilling causes a species-specific effect on Ca 2+ regulatory capabilities of spermatozoa that differs from cold shock and that spermatozoa may be able to compensate, at least partially, for such injuries.

Nucleosides LIII Syntheses and Reactions of 6,7-Dipyridyllumazine and 2' -Deoxylumazine N-1 Nucleosides

Summary The chemical syntheses of 6,7-(α-pyridyl)-1-(2,3,5-tri-O-benzoy-β-D-ribofuranosyl)-lumazine (6) and the corresponding free nucleoside 7 are described. Thiation of 6 with P4S10 gave a salt type adduct derivative of 4-thiolumazine 8 which afforded the free nucleoside 9 on deblocking. Treatment of 8 with methanolic NH3 gave the isopterin-N-1 nucleoside 10. 2,2' -Anhydro compound 13 was obtained by the diphenyl carbonate technique and characterised as the diacetate 14. Acid hydrolysis of 14 gave the arabino-nucleoside 15. which was isolated also from hydrolysis of 14 with hydroxide ion. Reaction of 7 with acetyl bromide gave the 2'-bromo-2'-deoxy derivative 11 as minor product together with triacetate 12 as the main analogue. Reduction of the bromo function in 11 into the expected 2'-deoxy analogue during the treatment with tri-n-butyltin hydride has failed and the 2.2' -anhydro compound 15 was the only product isolated. Alternatively. the 6,7-bis-(α-pyridyl)-1-(2-deoxy-3.5-di-O-toloulyl-α and β-D-ribofuranosyl)-Iumazine (17) and (19) were synthesized from direct condensation of sugar 16 and the silylated base 4. Debolcking of 17 and 19 with sodium methoxide gave the free analogues 18 and 20 respectively.

Biodistribution and tumor uptake of [ 67Ga]chlorogallium-tetraoctadecyloxy phthalocyanine and its sulfonation products in tumor bearing C3H mice

To evaluate the biodistribution and tumor uptake of chlorogallium tetraoctadecyloxy phthalocyanine, a potential new drug for the photodynamic therapy of cancer, we prepared the radioactive 67Ga-labeled complex and its water soluble sulfonated derivative. The non-sulfonated dye was obtained by condensation of octadecyloxyphthalonitrile in the presence of a mixture of 67Ga and 69Ga chloride. The sulfonated derivative was obtained by treatment of the condensation product with oleum. As singlet molecular oxygen has been implicated in the photodynamic action of phthalocyanines (Pcs), the quantum yield of singlet oxygen ( φ Δ ) was evaluated for chlorogallium tetraoctadecyloxy Pc, and also its zinc, aluminum and metal free analogues. After intraperitoneal administration of the non-sulfonated dye into RIF tumor bearing C3H mice, a very high 67Ga-uptake was observed in the spleen, while tumor radioactivity remained low during the 3 day study. The in vivo stability of the 67Ga-phthalocyanine complex was confirmed by comparing the distribution pattern with that of 67Ga-citrate, which proved to be significantly different. Intravenous injection of the sulfonated dye resulted in an overall lowering of 67Ga-uptake by most tissues, particularly in the spleen, while tumor radioactivities were slightly higher. These data suggest that amphiphilic photosensitizers, containing both polar sulfonate groups and long aliphatic substituents, exhibit the best distribution pattern for both imaging and photodynamic therapy of tumors.

A new example of ‘independence’ and ‘white noise’

We examine the notion of ‘free independence’ according to Voiculescu. This form of independence is used for defining ‘free white noise’ or ‘process with stationary and freely independent increments’. We prove a general limit theorem giving the combinatorics of infinitely freely divisible states and thus of free white noises with the help of ‘admissible’ partitions. We realize the free analogues of the Wiener process and of the Poisson process as processes on the full Fock space ofL 2 (—).

Oxidation of methane to formaldehyde over supported molybdena catalysts at ambient pressure: isolation of the selective oxidation product.

Two series of molybdena catalysts supported on a copper treated fumed silica were prepared and their properties for the selective oxidation of methane to formaldehyde were compared with the copper free analogs. The catalysts were tested at ambient pressure in a fixed bed microreactor using a 5:1 CH4:N2O mixture in the temperature range 500–600C. In a second series of tests the propensity of silica and alumina supports to catalyse the decomposition of formaldehyde was assessed. The copper free catalysts lost their selectivity to formaldehyde when the MoO3 loading exceeded 5wt% but loadings up to 15wt% were possible with two copper treated supports without loss of selectivity. Yield of formaldehyde was superior over the copper treated catalysts also. This improved performance was associated with the ability of metallic copper to act as a co-catalyst and increasing the lability of the lattice oxygen in the supported molybdena phase. On all catalysts combustion of formaldehyde in the catalytic reactor occurred and the second series of tests showed that this combustion could occur also on the support material.

Anti-5-hydroxytryptamine antibodies: studies on their cross-reactivity in vitro and their immunohistochemical specificity.

Antibodies to 5-hydroxytryptamine (5-HT) were obtained from 4 rabbits after injections of 5-HT coupled to bovine serum albumin by means of paraformaldehyde (PF). Two methods were used to monitor the development of antibodies (AB): the one based on the "in vitro" competitive binding properties of the antibodies with 3(H)5-HT, the other, on their "in situ" binding properties to endogenous 5-HT, using the peroxidase-anti-peroxidase immunohistochemical technique, applied to paraffin embedded sections of cat brainstem. No pharmacological processing, detergents or proteolytic enzymes were used. The specificity of the antiserum was tested by competitive procedures with 20 analogs using the "in vitro" and "in situ" techniques. "In vitro" studies were performed with 5-HT free analogs and with analogs previously coupled with PF to lysine. Radioimmunological tests showed that the antibodies recognize mainly the ethylamine (CH2-CH2-NH2)-chain of the free analogs and that the best specificity was obtained with the 5-HT conjugate (5-HT-lysine-PF). The results suggest that the hapten is coupled through the phenolic positions C4 or C5. The "in situ" immunohistochemical extinction assays also revealed a distinct specificity for 5-HT. Possible optical and ultrastructural applications are illustrated in the raphé nuclei of the cat. These results confirm the reliability of radioimmunological tests for studying the specificity of AB directed against haptens, provided that haptens and analogs tested were first chemically transformed to resemble the immunogen (herewith lysine-PF coupling) with regard to its antigenic structure.

Photochemical deoxygenation of an α-ketol: the dihydroflavonol–flavanone conversion

Irradiation of optically pure 2,3-trans-3-hydroxyflavanones in anhydrous ethyl acetate leads directly to free phenolic flavanone analogues with complete retention of configuration at C(2). Similarly their methyl ethers give the corresponding flavanones and flavones. The reaction represents the photochemical equivalent of a reduction under Clemmensen conditions.

EARLY TREATMENT OF COMPLETE ORNITHINE TRANSCARBAMYLASE DEFICIENCY WITH KETO ANALOGUES OF ESSENTIAL AMINO ACIDS

Complete deficiency of the urea cycle enzyme, ornithine trans-carbamylase (OTC), causes hyperammonemia and death in the neonatal period. Past therapeutic attempts have been singularly unrewarding. We now report treatment of such a male infant (hepatic OTC activity 0.1% of control) from the second day of life with a dietary regimen in which a mixture of essential amino acids and their nitrogen free analogues supplements a protein-restricted milk-based formula. Milk protein (1 g/kg/d) is supplied by standard infant formula and caloric needs (130 Cal/kg/d) and trace elements by a synthetic, protein-free product. To this formula is added a mix consisting of threonine, histidine, lysine, tryptophan, and arginine, plus the keto analogues of valine, leucine, isoleucine and the hydroxy analogues of methionine and phenylalanine, each in a quantity exceeding the infant's daily requirements. On this regimen the child has grown normally to the present time (age 9 wks) and his blood ammonia concentrations are persistently within normal limits (<150 μg/dl). Balance studies have shown normal nitrogen retention for age and intake. Plasma amino acid concentrations are near normal with the exception of reduced values for the branched chain amino acids and arginine which necessitated dietary adjustment at age 6 wks. To our knowledge this child now has lived longer than any previously reported infant with OTC deficiency of this severity.

THE MECHANISM OF HYPERAMMONEMIA IN CITRULLINEMIA

The hyperammonemia which occurs in patients with enzyme deficiencies of the urea cycle, apart from carbamyl phosphate synthetase (CPS) deficiency, is unexplained. In CPS deficiency, ammonium (NH4 +) is a substrate for the reaction and thus it accumulates. In argininosuccinic acid synthetase deficiency accumulation of citrulline (cit) is readily explained but accumulation of NH4 + is not because although the ornithine transcarbamylase reaction is reversible the CPS reaction is irreversible and not product inhibited. The relationship between plasma levels of NH4+ and other urea precursors was explored in a case of neonatal onset citrullinemia during 2-1/2 months of management with protein restriction and dietary supplements of nitrogen free analogues of essential amino acids. When plasma cit was 2 mM or less, hyperammonemia was not observed. At higher cit levels, NH4+ rose with cit (r=.65, p<.01). Significant positive correlations were also seen between plasma NH4+ and glutamine (gln) (r=.71, p<.01), NH4+ and glutamate (r=.58, p<.01), and NH4+ and alanine (r=.37, p<.01). The two amino adds giving the best prediction of NH4+ concentration were gln and cit: [NH4]=-20+(.327±.52) [gln]+ (.012±.001) [cit]; (r=.71, F=85.47, d.f.=71). Orotic aciduria occurred only when hyperammonemia was present. These findings suggest that hyperammonemia is a consequence of accumulation of cit, leading in turn to accumulation of carbamyl phosphate which constantly decomposes, releasing ammonium.

Properties of 4-ethenyl and 4-ethynyl analogs of pyridoxal phosphate and their reactions with the apo form of asparatate aminotransferase.

The binding to apoaspartate aminotransferase of analogs of pyridoxal phosphate bearing vinyl, cis- and trans-methylvinyl, and ethynyl groups in place of the fomyl group of the coenzyme has been studied. Details of synthesis of the ethynyl compound are given. The absorption spectra of all of the compounds have been analyzed and pKa values have been determined. The positions of the absorption bands can be related to those of pyridoxine but with bathochromic shifts induced by the ethenyl and ethynyl groups. However, this shift is almost completely lacking for the cis-methylvinyl compound suggesting nonplanarity of the molecule. Binding of the analogs to the apoenzyme is accompanied by a strong bathochromic shift which, from a study of solvent effects on the free analogs, appears to indicate a hydrophobic environment on the enzyme. Nevertheless, the analogs are bound as dipolar ions exclusively. Binding is accompanied by a distinct perturbation of the protein spectrum in the aromatic region. An effect on the spectrum of 1 or more tryptophan residues is indicated. Bands of the bound analogs exhibit positive circular dichroism except for that of the 4-vinyl analog. The 4-ethynyl analog reacts in a more complex way, giving at least two successive products in addition to the initial complex. The final product is reducible by sodium borohydride, is released from the enzyme by boiling, and appears to have the properties of a Schiff base. We postulate that the addition of an amino group of the enzyme to the ethynyl group is followed by tautomeric rearrangement to a Schiff base in which the ring is in a p-quinonoid structure.

Characterization ofN-succinyl metabolites of adenine and aminoimidazole carboxamide by mass spectrometry

N6-(2-succinyl)adenosine 5′-phosphate and N-(5-amino-1-ribosyl-4-imidazole carbonyl)-L-aspartic acid ′-phosphate were prepared enzymatically using adenylosuccinate lyase (EC 4.3.2.2) isolated from human erythrocytes. N6-(2-succinyl)adenosine 5′-phosphate, N-(5-amino-1-ribosyl-4-imidazole carbonyl)-L-aspartic acid 5′-phosphate and N-(5-amino-1-ribosyl-4-imidazole carboxamide) 5′-phosphate and the nucleoside and free base analogs of these nucleotides were converted to the trimethylsilyl derivatives and characterized by mass spectrometry. The extent of the trimethylsilylation was greater for adenine substituted compounds compared with those related to aminoimidazole carboxamide. Major mass spectral fragment ions correspond to the intact base plus portions of the sugar skeleton and to electron impact-induced decomposition products of the sugar moiety. Succinyl substitution at N6 of the adenine derivatives leads to characteristic loss of CO2 SiMe3 from the molecular ion. A combination of liquid chromatographic procedures and gas chromatography mass spectrometry gave rapid and unequivocal identification of succinyladenine from human urine.

Incorporation of proline analogues into collagen polypeptides Effects on the production of extracellular procollagen and on the stability of the triple-helical structure of the molecule

The effects of several proline analogues on collagen biosynthesis were examined in freshly isolated cells from embryonic tendon. Four analogues which were previously shown to be incorporated into collagen were found to decrease the amount of newly synthesized 14C-labeled procollagen recovered in the medium after incubation of the cells for 2–3 h. The decreased production of extracellular procollagen was not explained by inhibition of protein synthesis, failure of the procollagen to form interchain disulfide bonds, or any effects of the free analogues on hydroxylation of 14C-labeled protocollagen or secretion of 14C-labeled procollagen which did not contain the analogues. The specific effects of the four proline analogues on collagen could be explained by the hypothesis that the presence of the analogues in the polypeptide chains prevents them from assuming the normal triple-helical conformation of collagen and as a result the polypeptides are degraded. This hypothesis was supported by the observation that the concentration of the effective analogues which blocked the production of extracellular 14C-labeled procollagen also decreased the amount of intracellular 14C-labeled procollagen which was in a helical conformation as judged by its resistance to proteolytic digestion. With the same concentrations of analogues there was an increase in the amount of small 14C-labeled peptides in the medium and an increase in the rate of degradation of collagen 14C-labeled polypeptides. The protein containing the proline analogues did not become helical on cooling to 15 C under conditions in which protocollagen became helical. Therefore the decreased tendency of the polypeptides to become triple-helical could not be explained simply by their apparently low content of trans-hydroxyproline and the

Derivative free analogues of the Levenberg-Marquardt and Gauss algorithms for nonlinear least squares approximation

In this paper we give two derivative-free computational algorithms for nonlinear least squares approximation. The algorithms are finite difference analogues of the Levenberg-Marquardt and Gauss methods. Local convergence theorems for the algorithms are proven. In the special case when the residuals are zero at the minimum, we show that certain computationally simple choices of the parameters lead to quadratic convergence. Numerical examples are included.

Structural analysis of C 19-Steroids by means of chromatography

The behaviour of the acetates, formates, dinitrophenylhydrazones, bromides and some oxidation products of C 19-steroids has been studied by means of paper and thin-layer chromatography. The mobility of the derivatives has been compared with that of their free analogues. Δ R Mr values obtained on the conversion of certain functional groups are presented.