bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interleukin‐1β contributes to the generation of experimental febrile seizures
Authors: Dubé Celine , Vezzani Annamaria , Behrens Marga , Bartfai Tamas , Baram Tallie Z. 
Published: December 2004

AbstractFever can provoke “febrile” seizures (FS). Because complex FS may promote development of temporal lobe epilepsy, understanding their mechanisms is clinically important. Using an immature rodent model and transgenic technology, we examined the role of interleukin‐1β, (IL‐1β), a pyrogenic, proinflammatory cytokine, in FS. IL‐1β receptor–deficient mice were resistant to experimental FS. This resistance appeared independent of genetic background and was attributed to lack of IL‐1β signaling, because exogenous cytokine reduced seizure threshold in wild‐type but not receptor‐deficient mice independent of strain. In addition, high IL‐1β doses induced seizures only in IL‐1β receptor–expressing mice. These data indicate that IL‐1β signaling contributes critically to fever‐induced hyperexcitability underlying FS, constituting a potential target for their prevention. Ann Neurol 2005;57:152–155An Erratum has been published for this article in Ann Neurol 57: 609, 2005.
Pick bodies in a family with presenilin‐1 Alzheimer's disease
Authors: Halliday Glenda M. , Song Yun Ju C. , Lepar Gila , Brooks William S. , Kwok John B. , Kersaitis Cindy , Gregory Gillian , Shepherd Claire E. , Rahimi Farid , Schofield Peter R. , Kril Jillian J. 
Published: December 2004

AbstractPresenilin‐1 (PS‐1) mutations can cause Pick's disease without evidence of Alzheimer's disease (AD). We describe a family with a PS‐1 M146L mutation and both Pick bodies and AD. Sarkosyl‐insoluble hyperphosphorylated tau showed three bands consistent with AD, although dephosphorylation showed primarily three‐repeat isoforms. M146L mutant PS‐1 may predispose to both Pick's disease and AD by affecting multiple intracellular pathways involving tau phosphorylation and amyloid metabolism. Ann Neurol 2005;57:139–143
Band centrifugation of macromolecules in self‐generating density gradients. II. Sedimentation and diffusion of macromolecules in bands
Authors: Vinograd Jerome , Bruner Robert 
Published: December 2004

AbstractThree approaches to the simultaneous sedimentation and diffusion of hands or zones of noninteracting homogeneous macromolecules are examined: (1) The authors' method of moments: (2) the transport me of Sehumaker and Rosenbloom; and (3) the stochastic solution of the Lamm equation due to Gehatia and Katehalski. All three methods indicate that the motion of the maximum of the hand may be used to evaluate the sedimentation coefficient. The moment, method provides relations which appear to be useful for measuring diffusion coefficients. Relations are given for the analysis of resolved components. The problem of measuring sedimentation coefficients of macromolecules with concentration‐dependent sedimentation coefficients is examined. Methods are described for evaluating the sedimentation coefficient in these systems and for obtaining the sedimentation coefficient at infinite dilution. Methods are described for determining the weight‐average sedimentation coefficient in Multi‐component systems, and the differential and integral distribution of sedimentation coefficients of macromolecules with low‐diffusion coefficients.
Charge density on native and ultraviolet‐irradiated myosin A
Authors: Westley Francis , Kaldor George , Cohen Irving 
Published: December 2004

AbstractThe axial ratios (a/b) of native and 60 min. ultraviolet‐irradiated myosin A molecules were calculated from previously reported sedimentation and diffusion data; values found were a/b = 74, a = 1880 A., and b = 26 A. for native myosin A; a/b = 104, a = 3280 A., and b = 32 A. for 60 min. ultraviolet‐irradiated myosin A. Electrophoretic mobilities gave identical values of 3.2 (±0.1) × 10−5 cm.2/v.‐sec. for both native and 60 min. ultraviolet‐irradiated myosin A. From the prior sedimentation and diffusion data, together with newly obtained electrophoretic data, the net charge Z and the charge density σ of native and ultraviolet‐irradiated myosin A molecules were calculated from Henry's equation. The following results were obtained: for native myosin A, Z = 160 negative charges per molecule and σ = 22 coulombs/cm.2; for ultraviolet‐irradiated myosin A, Z = 312 negative charges per molecule and σ = 20 coulombs/cm.2. The results of this study provide an experimental demonstration that, the electrophoretic mobility of charged solute particles is dependent upon the particle charge density and not on the absolute charge of the particle.
Differential thermographic features of some crystalline biopolymers
Authors: Morita Hirokazu 
Published: December 2004

AbstractCrystalline proteins, nucleic acids, nucleotides, and nucleosides have been examined by differential thermal analysis. Characteristic thermograms are illustrated for globular, serum, and blood plasma proteins, calf thymus DNA, sodium triticonucleate, sodium thymonucleate, sperm DNA, yeast RNA, adenosine‐3′‐phosphate, adenosine‐5′‐phosphate, disodium adenosine triphosphate, adenosine, and deoxyadenosine. A pronounced effect of moisture on the differential thermal properties of DNA has been observed. It is suggested that solid‐state denaturation is one of the prominent thermal effects recorded by the differential thermal analysis of proteins and nucleic acids.
Studies on nucleic acids. VIII. Changes in the stability of DNA secondary structure by interaction with divalent metal ions
Authors: Venner H. , Zimmer Ch. 
Published: December 2004

AbstractThe melting temperature of a natural DNA is decreased in the presence of increasing amounts of copper ions, whereas other divalent metal ions stabilize the DNA secondary structure at low ionic strength. At 1.28 × 10−4M, Cu2+ produces a decrease of Tm depending on base composition. At very low Cu2+ concentrations (0.5 Cu2+/2 DNA‐P) a stabilization of the DNA conformation appears due to an interaction between Cu2+ and phosphate groups of the DNA molecule. In this case the normal trend of GC dependence of Tm exists similar to that with Na+ and Mg2+ as counterions. If copper ions are in excess, the observed destabilization is stronger for DNAs rich in guanine plus cytosine than for those rich in adenine plus thymine. A sharp decrease of Tm occurs between 0.5–0.8 Cu2+/2 DNA‐P and 1.5 Cu2+/2 DNA‐P. The breadth of the transition decreases at high Cu2+ concentration with further addition of copper ions. Denaturation and renaturation experiments indicate that Cu2+ ions exceeding the phosphate equivalents interact with the bases and reduce the forces of the DNA helix conformation. Evidence is presented, that the destabilization effect produced by Cu2+ is possibly due to an interaction with guanine sites of the DNA molecule.
Interaction of polynuclear aromatic hydrocarbons, 4‐nitroquinoline 1‐oxides, and various dyes with DNA
Authors: Nagata Chikayoshi , Kodama Masahiko , Tagashira Yusaku , Imamura Akira 
Published: December 2004

AbstractBy using the flow dichroism method, in vitro interaction of the aromatic polynuclear hydrocarbons with calf thymus DNA was studied. A clear dichroism of the hydrocarbons which interacted with DNA was observed, showing a specific type of interaction. Hydrocarbons were classified into two groups, depending on whether the orientation is parallel or perpendicular to the direction of flow. 3,4‐Benzopyrene, pyrene, and phenanthrene belong to the first group, and the second group contains 20‐methylcholanthrene, tetracene, pentacene, and coronene. 4‐Nitroquinoline 1‐oxide (4‐NQO) and its derivatives have also been found to be oriented parallel to the planes of bases of DNA, and a distinct parallel was found between the amount of binding and carcinogenicity. Base specificity of binding of 4‐NQO with DNA‐was studied, and purines were suggested to be active sites of interaction. Actinomycin D, several acridine dyes, and methylene blue etc. were found to be oriented parallel to the planes of DNA bases, and in the cases of acridine dyes this finding does not contradict the intercalation mechanism proposed by Lerman.
Electric properties of macromolecules. IX. Dipole moment, polarizability, and optical anisotropy factor of collagen in solution from electric birefringence
Authors: Yoshioka Koshiro , O'konski Chester T. 
Published: December 2004

AbstractThe electric birefringence of collagen solutions has been measured over a wide range of field strength with the pulse technique. The soluble collagen was from rat tail tendon. The solvent used was dilute acetic acid. Very pronounced saturation of the electric birefringence was observed, permitting calculation of the optical anisotropy factor. The Kerr constant was determined by extrapolation to zero field strength. From the dependence on field strength of the birefringence, the permanent dipole moment and the anisotropy of polarizability were separately determined. The contribution of the former to the Kerr constant was found to be twice as large as that of the latter. The same conclusion was obtained from the initial slope of the rise curves of the birefringence at low fields. The permanent dipole moment was 1.5 × 104 Debye, and the anisotropy of polarizability was about 3 × 10−15 cm.3. The magnitude of the latter indicates that the ion atmosphere polarization is important. Effects of added salt and thermal denaturation on the electric birefringence were explored.
Circular dichroism measurements of benzyl L‐aspartate–nitrobenzyl L‐aspartate copolymers and their use in detecting and characterizing preferred polymer conformations
Authors: Bradley Dan F. , Goodman Murray , Felix Arthur , Records Ruth 
Published: December 2004

AbstractWe have examined the nature of the circular dichroism band at 330 mμ for a series of copolymers of β‐p‐nitrobenzyl L‐aspartate with β‐benzyl L‐aspartate. The circular dichroism band arises from an electronic transition in the nitroaromatic group. In order to interpret the effect quantitatively, we employed a simplified statistical treatment and curve fitting for six copolymers. Both approaches gave consistent results, which indicates that the dichroism comes from pairwise interactions between two nitrobenzyl groups. We constructed a molecular model that meets the constraints and requirements of the analyses developed in this paper. In this model, it is proposed that the main chain forms a right‐handed α‐helix and that nitrobenzyl groups separated by four residues interact with each other.
The V amylose–water system: Enthalpy of hydration on the helix exterior
Authors: Nicolson P. C. , Yuen G. U. , Zaslow B. 
Published: December 2004

AbstractThe reaction, V amylose hydrate ⇄ H2O + V amylose dehydrate, where the amylose hydrate and dehydrate are pseudohexagonal, helical species with packing diameters of 13.7 and 13.0 A., respectively, has been studied. The V amyloses were exposed to water vapor pressures at various temperatures, with phase determination obtained by identifying solid reactant and product from their x‐ray patterns. Reversibility of reaction was found to occur over a 50–96°C. range. A Clausius‐Clapeyron plot yields a ΔH of reaction of 10.4 kcal./mole of water released, which value is close to analogous heats of reaction of many common hydrate systems.
Nature of Cu(II)‐poly(glutamic acid) complex in aqueous solution
Authors: Takesada Hiroko , Yamazaki Hideo , Wada Akiyoshi 
Published: December 2004

AbstractComplex formation of poly(glutumic acid) with cupric ions in aqueous solution was investigated by three different methods: optical spectroscopy, optical rotatory dispersion, and electron spin resonance. Formation of a characteristic complex was found to occur in a pH region suitable for the helix‐coil transition. An analysis of the ESH spectrum of the complex is given, and the results of calculation of bonding parameters suggest that the bond between copper and nitrogen atoms had an appreciably covalent character. The change in the secondary structure of the polymer as a result of complex formation is discussed.
Base composition of intact nucleic acid oligomers
Authors: Mandeles Stanley , Cantor Charles R. 
Published: December 2004

AbstractThe base composition of intact, purified, oligonucleotides has been determined by comparing the absorption spectrum of each oligomer with calculated curves. The spectral curve of each oligomer was measured in 7M urea at three pH values and digitized at 1‐mμ intervals. The calculated curves consisted of the sums of the absorption spectra of mononucleotides in 7M urea at the same pH's. A computer was used to make the comparisons and establish the best fit. Results are presented for nine of the ten possible dimer composition isomers; trimers from pancreatic and T1 ribonuclease hydrolyzates of TMV‐RNA; poly‐A, poly‐C, and poly‐U; and intact tobacco mosaic virus‐RNA.
Validity of the “two‐state” hypothesis for conformational transitions of proteins
Authors: Lumry Rufus , Biltonen Rodney , Brandts John F. 
Published: December 2004

AbstractThe theory, character, and properties of cooperative transitions are developed with special reference to the abrupt changes of state which occur in protein solutions. Comparisons of helix–coil processes and protein conformational reactions show that though cooperation dominates both of these processes, there are important differences. Tests of two types for the validity of the two‐state approximation are presented with specific applications to proteins. Available experimental evidence demonstrates that the thermally induced reversible transitions of ribonuclease, α‐chymotrypsin, and chymotrypsinogen A under conditions thus far examined are two‐state processes.
The helix–coil transformation for tropocollagen solutions and its relationship to transformations involving the crystalline form of the protein
Authors: Bianchi Estella , Conio Giuseppina , Ciferri Alberto 
Published: December 2004

AbstractCollagen molecules can exist, in the aggregate crystalline state (C) and in solutions, as tropocollagen helices (H) or random coils (RC). We have compared the role of temperature, salt type, and salt concentration, C8, on the transformations: C → RC (I), H → RC (II), and H → C (III) under near‐isoelectric conditions. Processes I and II occur in the direction from ordered to disordered form on increasing temperature, while process III occurs in the direction crystal → dissolved helices on lowering temperature. The order of both anions and cations for increasing the stability of the dissolved random coiled form is similar for processes I and II, but the order of the anions for increasing the stability of the dissolved helices, according to process III, is reversed with respect to the Hofmeister series. TI and TII are greatly and continuously depressed by some salts on increasing C8 while, for other salts, they are at first slightly depressed and then raised. TIII, instead, is at first raised and then lowered on increasing C8. For a given salt the field of stability of each form is determined, on a pseudo‐phase diagram, by the relative positions of the TI versus C8, the TII versus C8, and the TIII versus C8, curves. The similarity of the effect of temperature, salt type, and concentration on processes I and II supports the contention that both processes are controlled by the interaction of the random coiled form with the salt solution. The phenomenon of crystallization by increasing temperature is complicated by large time effects and, often by lack of reversibility. Assuming, nevertheless, that there is an underlying equilibrium process, two possible interpretations are proposed. The peculiar trend of the TIII versus C8 curve is justified on the basis that it reflects the usual change from salting in to salting out on increasing C8, allowing for the fact that the dissolved phase is stable in the low‐temperature range. The reversal of the order of anions for process III can be most simply justified in terms of the slight cat ionic character of the tropocollagen units. Accordingly, the dissolved helices will be more; stable of the crystalline form depending upon the occurrence of a net charge different from zero on the protein, as well as upon low ionic strength and low temperature. Minute alterations of KCl concentrations are able to cause isothermal precipitation of fibers and probably constitute a controlling factor for the fibrogenesis in vivo.
Structure and optical activity of the DNA–aminoacridine complex
Authors: Gardner B. J. , Mason S. F. 
Published: December 2004

AbstractThe electronic absorption and circular dichroism spectra of the DNA‐acridine orange complex have been measured over a range of ionic strength, pH, and DNA phosphate to dye (P/D) ratios. Three circular dichroism bands associated with the long wavelength absorption band of acridine orange are induced on complex formation with DNA. Two of the dichroism bands, due mainly to dimeric dye molecules, are favored by low ionic strength, low pH (3.2), and a low P/D ratio (∼3), while the third, deriving primarily from monomeric dye, is optimum at high ionic strength, neutral pH, and a larger P/D ratio (9). The data suggest that monomeric acridine orange binds to DNA in the form of a left‐handed helical array with four dye molecules per turn, while the bound dimer has a skewed sandwich conformation which is itself dissymmetric. The stereochemical relations between the bound monomer dye and the DNA are consistent with a modified intercalation model for the DNA‐acridine complex.
Interaction of spermine and DNA
Authors: Hirschman Shalom Z. , Leng Marc , Felsenfeld Gary 
Published: December 2004

AbstractThe effect of spermine upon the denaturation temperature (Tm) of DNA's of various base compositions has been found to depend upon both the base composition of the DNA and the pH of the solution. Measurement of the hydrogen ion titration curve of spermine as a function of temperature reveals that the net charge of the spermine molecule is undergoing a rapid change with temperature in the range of temperatures at which DNA denatures. Since the value of Tm depends upon base composition, the correlation of the effect of spermine upon Tm with the base composition of the DNA used may be explainable in terms of the changing degree of ionization of spermine. The binding of spermine to native DNA has also been studied by dialysis equilibrium. There is no significant variation either in the number of strongly binding sites or strength of binding with base composition. It is concluded that there is no evidence of correlation between the binding of spermine and the base composition of DNA.
Extrinsic cotton effects of proflavine bound to polynucleotides
Authors: Blake A. , Peacocke A. R. 
Published: December 2004

AbstractThe magnitude of the Cotton effect of proflavine which is bound to RNA or to denatured DNA depends on the ratio of bound proflavine to nucleic acid base. A statistical treatment which explains this behavior has been fitted to the experimental curves and indicates that optical activity arises through interaction between two or more bound proflavine molecules. The corresponding requirement with double helical DNA is for interaction between 3–4 proflavine molecules. Although proflavine binds to denatured DNA at pH 2.8, as shown by the shift of the proflavine spectrum, the strong binding process is absent, and to this is attributed the absence of the Cotton effect at low pH. Studies on the Cotton effects of proflavine bound to poly A and poly U at neutral pH, to poly A at acid pH and to poly (A + U) allow the generalization that a relatively rigid configuration of the binding macromolecule is required for the induction of these extrinsic Cotton effects.
Interaction between proteins and salt solutions. IV. Enrichment of salts in collagen during denaturation
Authors: Ciferri A. , Garmon R. , Puett D. 
Published: December 2004

AbstractUsing 14C‐labeled KSCN and 36Cl‐labeled KC1, we have determined the selective removal of ions and water by fibrous, crosslinked collagen both below and above the denaturation temperatures at several molarities under or near isoelectric conditions. The results for KSCN show there is an increase in ion binding at the denaturation temperature. These data, in conjunction with date from the literature, have been used to evaluate binding constants and mole fractions of available binding sites, as well as the free energy of binding various salts to collagen and gelatin. The values so obtained correlate satisfactorily with similar quantities obtained from the experimental dependence of the shrinkage temperature of collagen on salt concentration using a simple theory for the melting point depression which includes the effect of binding in the denatured state. Salting‐out agents show negligible binding to the protein, and this confirms the earlier finding that the interaction between these agents and the protein can be approximately described by conventional polymer–diluent theories which do not consider ion binding. Also, an analysis of the role of unequal anion and cation binding is presented.
On the two kinds of nucleation in the helix–coil transition theory of polypeptide chains
Authors: Bixon M. , Lifson S. 
Published: December 2004

AbstractThe nucleation of a helical sequence from a random chain of the polypeptide molecule as well as the nucleation of a random‐coil sequence from the helical conformation of the molecule are considered simultaneously in evaluating the partition function of the system. This partition function is then used for a comparative analysis of the theories of Zimm and Bragg, Gibbs and DiMarzio, and Lifson and Roig. It is shown that while all three account properly for the essential nature of the nucleation phenomenon the first considers in detail the random‐coil nucleation, the second emphasizes the details of the helix nucleation, while the third neglects the fine details of both in a symmetric way.
Chemical synthesis of a dextran model, poly‐α‐(1 → 6)‐anhydro‐D‐glucopyranose
Authors: Ruckel Erwin R. , Schuerch Conrad 
Published: December 2004

AbstractPoly‐α‐(1 → 6)‐anhydro‐D‐glucopyranose has been synthesized by the phosphorus pentafluoride‐catalyzed polymerization of l,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose and subsequent debenzylation. Physical characterization establishes its high polymeric character and stereoregularity.
Structure and stability of complexes formed by nucleic acids. I. Binding of acridine to DNA
Authors: Bleaks D. J. , Danyluk S. S. 
Published: December 2004

AbstractNuclear magnetic resonance spectra of acridine have been measured in aqueous methanol solutions over a wide concentration range in the presence and absence of dissolved DNA. In solutions containing DNA the acridine spectra show a marked line broadening and intensity decrease at temperatures lower than 50°C. These line‐shape changes can be associated with two types of binding interactions: (1) a tight, irrotational binding of the acridine at low acridine:phosphate ratios and (2) a weaker, rotationally less restrictive binding at high acridine concentrations. At temperatures above 50°C. a marked line narrowing is noted for the acridine spectrum and is attributed to an increase in mobility of the bound acridine as the DNA complex undergoes a helix–coil transition. A loose association of acridine molecules with the purine and pyrimidine bases in heat‐denatured DNA is indicated by chemical shift changes in the acridine spectrum. The NMR measurements also show that the presence of acridine in denatured DNA solutions greatly reduces renaturation of the DNA.