bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventricular volume in man computed from CAT scans
Authors: Penn Richard D. , Belanger Michael G. , Yasnoff William A. 
Published: December 2004

AbstractA new interactive computer system has been developed to measure ventricular volume from CAT scans. Testing this system on phantoms demonstrated an accuracy to within 16%. Then a series of scans of patients with obstructive hydrocephalus was analyzed using both traditional linear measures and the computer method. None of the traditional measures were directly proportional to the calculated volume. The area measure of ventricular volume correlated well with the computer‐generated values. Clinical studies which attempt to quantitate ventricular volume should use a computerized or planigraphic measure.
A disorder of biogenic amines in dihydropteridine reductase deficiency
Authors: Butler Ian J. , Koslow Stephen H. , Krumholz Allan , Holtzman Neil A. , Kaufman Seymour 
Published: December 2004

AbstractA severe deficiency of dihydropteridine reductase (DHPR) in liver, brain, and cultured skin fibroblasts was demonstrated in a child with hyperphenylalaninemia and an atypical form of phenylketonuria. DHPR is required for regeneration of the cofactor, tetrahydrobiopterin. The cofactor is essential in hydroxylation of aromatic amino acid precursors in the biosynthesis of neurotransmitters, serotonin, dopamine, and norepinephrine. In gray tissue at brain biopsy, dopamine was low at 3 ng per gram of tissue, serotonin was barely detected, and norepinephrine appeared high at 1600 ng per gram. In cerebrospinal fluid, homovanillic acid (HVA) was low normal at 33 ng/ml, 5‐hydroxyindoleacetic acid (5‐HIAA) was low at 4.2 ng/ml, and after a high dose of oral probenecid there was impaired accumulation of HVA to 128 ng/ml and 5‐HIAA to 22.4 ng/ml. When the patient was 22 months of age, treatment with hydroxylated aromatic amino acid precursors was initiated, and after three months HVA and 5‐HIAA levels were increased in CSF. The apparent restoration of biogenic amines in brain appears to have delayed the rate of neurological deterioration. DHPR activity in cultured skin fibroblasts of children with persistent hyperphenylalaninemia should permit early diagnosis and early treatment of this disorder.
The cherry‐red spot‐myoclonus syndrome
Authors: Rapin Isabelle , Goldfischer Sidney , Katzman Robert , Engel Jerome , O'Brien John S. 
Published: December 2004

AbstractThree young women, 2 of them sisters, were found to have cherry‐red spots at the macula when they were children. In 1 patient the spots faded before she was 20 years old. In all 3, incapacitating myoclonus and insidious visual loss developed in adolescence. Their intellect is normal and they have no gargoyle‐like features. A variety of lysosomal inclusions were noted in cortical neurons in a biopsy specimen taken from 1 patient in childhood. Liver biopsy fifteen years later revealed mucopolysaccharide‐like inclusions in Kupffer cells and hepatocytes. Lipofuscin bodies were abundant in neurons and hepatocytes. The patients excrete sialic acid‐containing oligosaccharides not present in normal urine, suggesting a defect in degradation of glycoproteins. The specific enzymatic defect in these patients appears to be a deficiency of lysosomal neuraminidase.
Predictors of mortality in presenile and senile dementia
Authors: Kaszniak Alfred W. , Fox Jacob , Gandell David L. , Garron David C. , Huckman Michael S. , Ramsey Ruth G. 
Published: December 2004

AbstractForty‐seven hospitalized patients with a diagnosis of presenile or senile dementia and without focal neurological disease or major systemic illness were given complete neurological, neuroradiological, and neuropsychological examinations. Mortality at one year after hospitalization was determined, 12 patients being lost to follow‐up. Of the remaining 35 patients, 19 were alive and 16 had died. These two groups did not differ in age, education, length of dementia history, sex, race, or degree of cerebral atrophy (by computerized tomography). Significant differences were found in degree of electroencephalographic abnormality and in 8 of 14 cognitive measures, the largest single difference being on a test of expressive language. Discriminant function analysis made with the cognitive measures as dependent variables yielded a correct prediction (classification analysis) of mortality in all but 1 case (97% accuracy). These results suggest that (1) degree of functional brain impairment rather than degree of cerebral atrophy may be the more important influence on mortality in dementia patients without focal lesions, (2) short‐term survival may be accurately predicted in such patients by tests of cognitive functioning, and (3) expressive language deficit in such patients may indicate a particularly poor prognosis for survival.
Perhexiline neuropathy: A clinicopathological study
Authors: Said Gérard 
Published: December 2004

AbstractFive patients developed a mild to severe polyneuropathy while under treatment with perhexiline maleate, a drug used in long‐term treatment for angina pectoris. Recovery took place within a few months after drug withdrawal.We performed qualitative and quantitative light and electron microscopical studies, including teased fiber preparations, in different patients; 16 to 90% of the fibers showed segmental demyelination, an unusual feature in drug‐induced neuropathies, and 3 to 20% were undergoing wallerian degeneration. Severe loss of myelinated axons was noted in all 5 patients. In these patients clinical symptoms occurred only when a great number of fibers had already been lost and most of the surviving fibers showed demylination.
Changing patterns of childhood aphasia
Authors: Woods Bryan T. , Teuber Hans‐Lukas 
Published: December 2004

AbstractAcquired aphasia in children has been generally characterized as nonfluent, transient, and frequently due to right hemisphere lesions. We studied 65 children with unilateral hemispheric brain lesions occurring after speech acquisition any time from the second through the fourteenth year. Of 34 patients with a left hemisphere lesion, 25 had an initial aphasic speech disturbance, while of 31 patients with a right hemisphere lesion, only 4 (including 2 lefthanders) showed any initial aphasia. All those who became aphasic before the age of 8 years eventually regained speech, but recovery time required ranged from less than a month to more than two years. One 5‐year‐old boy who recovered had initial jargon aphasia. Our review of the literature indicated that the conflict between our results and the traditional claim of frequent aphasia with right hemisphere lesions was only apparent; the great majority of crossed aphasias are concentrated in reports written before antibiotics were used, and many cases were associated with systemic bacterial infections.
Monoligated Palladium Species as Catalysts in Cross‐Coupling Reactions
Authors: Christmann Ute , Vilar Ramón 
Published: December 2004

AbstractPalladium‐mediated cross‐coupling reactions are attractive organometallic transformations for the generation of CC, CN, CO, and CS bonds. Despite being widely employed in small‐scale syntheses, cross‐coupling reactions have not found important industrial applications because until recently, only reactive aryl bromides and iodides could be used as substrates. These substrates are generally more expensive and less widely available than their chloride counterparts. Over the past few years, new catalytic systems with the ability to activate unreactive and sterically hindered aryl chlorides have been developed. The new catalysts are based on palladium complexes that contain electron‐rich and bulky phosphine or carbene ligands. The enhanced reactivity observed with these new systems has been attributed to the formation of unsaturated and reactive [PdL] species which can readily undergo oxidative addition reactions with ArX to yield [Pd(Ar)X(L)].
An analysis of optical rotatory dispersion curves of synthetic polypeptides
Authors: Yamaoka K. K. 
Published: December 2004

AbstractA two‐term Drude equation was proposed to he substituted for the Moffitt‐Yang equation as an empirical expression in order to analyze and regenerate observed optical rotatory dispersion (ORD) curves of synthetic polypeptides and proteins. A convenient graphical method was introduced to evaluate four parameters involved in the present expression. The method was demonstrated in detail with an observed ORD curve of sodium poly‐α, L‐glutamate (NaPLG) at pH 4.35. A number of ORD curves of poly‐γ‐benzyl‐L‐glutamate (PBLG) in both helix and random‐coil were analyzed. For all ORD curves examined, the critical wavelengths, λ0 and λ1, were found to be 193 and 226 mμ. Aromatic solvents wore found to constitute a group distinct from other helix‐forming solvents. A far ultraviolet ORD curve of NaPLG was also analyzed with use of Natanson's equation which contains two damping factors. It was concluded that for an exact description of the ORD curve of helical polypeptides a third term, probably negative, should be taken under consideration. An illustrative application of the present method to the data of the helix‐coil transition of NaPLG shed much light on the relation between the four parameters and its molecular conformation as a function of pH.
Electrophoresis of DNA. III. The effect of several univalent electrolytes on the mobility of DNA
Authors: Ross Philip D. , Scruggs Robert L. 
Published: December 2004

AbstractThe electrophoretic mobility of DNA in the presence of tetramethylammonium and alkali metal ion chlorides has been studied as a function of ionic strength. Each cation exhibits a characteristic behavior in accord with the idea that the order of inter‐action with DNA is Li+ > Na+ > K+ > TMA+. The application of theories of the electrophoresis of polyelectrolytes is discussed, leading to an attempt to calculate the fractional charge per DNA phosphorus from the mobility data. Over the range 0.05–0.4M a constant and unique value of the DNA charge is obtained in the presence of each cation. Values of the zeta potential and of the friction factor per monomer unit are also calculated.
The exclusion of large solutes by cartilage proteinpolysaccharide
Authors: Gerber Bernard R. , Schubert Maxwell 
Published: December 2004

AbstractThe dialysis technique of Ogston and Phelps, using a Millipore filter as a membrane to measure the effect of a nondialyzable macromolecule on the distribution of dialyzable macromolecules, has been used to measure the effect of a compound of protein and polysaccharide (PP‐L), isolated from cartilage, on the distribution of some dialyzable macromolecules. PP‐L (1%) in buffer acts as if part of its solution volume were unavailable as follows: 55% for serum albumin, 64% for chondroitin sulfate made by alkaline degradation of PP‐L, and 98% for chondroitin sulfate made by trypsin degradation of PP‐L. The use of different buffers, variation of pH from 5 to 10, variation of temperature from 5 to 42°C., variation of salt concentration from 0.15 to 2N, and variation in ethanol concentration from 0 to 30% had no effect on the distribution of albumin, which was always excluded to about the same extent from the PP‐L solution. This effect could account for the virtual absence of serum proteins and of free chondroitin sulfate from cartilage. At low salt concentration (0.10–0.02N) and at 5°C, the distribution was reversed and albumin behaved as if strongly bound by PP‐L. At low‐levels of albumin this binding of PP‐L increased linearly with albumin concentration. This binding was partly reversed by raising the temperature or by adding urea, and completely reversed by the addition of salt. Polystyrene sulfonate, a nondiffusible polyanion, had an effect similar to that of PP‐L in excluding chondroitin sulfate from its solutions. It showed a very strong binding effect for albumin which persisted even in the presence of salt as high as 2N. A quantitative comparison has been made between the excluded volume effect of the soluble macromolecules PP‐L and hyaluronate and the effect of insoluble Sephadex particles to exclude large molecules from their interiors. The technique of Ogston and Phelps is thus valuable‐ not only for measuring the exclusion of diffusible macromolecules from part of the solution volume of nondiffusible macromolecules, but also for measuring the existence and extent of binding of diffusible macromolecules to nondiffusible macromolecules.
The conversion of two‐stranded poly (A + U) to, three‐strand poly (A + 2U) and poly A by heat
Authors: Stevens Charles L. , Felsenfeld Gary 
Published: December 2004

AbstractIt is shown that the formation of the three‐strand poly (A + 2U) complex is accompanied by a decrease in optical absorbance at 280 mμ, while the format ion of poly (A + U) is not. This difference makes it possible to demonstrate that in dilute solutions (∼10−4 monomolar), a 1 : 1 mixture of poly A and poly U always forms poly (A + U) at room temperature. At higher temperatures in solutions containing more than about 0.2M sodium ion, poly (A + U) is converted to poly (A + 2U) and free poly A. These results are consistent with the observations reported by Miles and Frazier, using infrared absorption spectra, at much higher polymer concentrations. It is concluded that most of the physicochemical studies of 1 : 1 mixtures of poly A and poly U in dilute aqueous solution refer to the two‐stranded species.A simple thermodynamic analysis is developed to explain the two‐ to three‐strand conversion, and with the use of a “phase diagram” showing conditions of stability of the various poly A–poly U structures as a function of salt and temperature, it is possible to estimate the value of the enthalpy of formation of poly (A + 2U).
A physical study of the degradation of periodate–oxidized amylose
Authors: Erlander Stig R. , Griffin H. L. , Senti F. R. 
Published: December 2004

AbstractChanges in the viscosity of amylose that had been oxidized In an aqueous medium at pH 3.0 by sodium metaperiodate were followed as a function of time. Levels of 20, 40, 60, 80, and 100% periodate oxidation were attained. The rate of hydroxyl ion cleavage of the periodate oxidized amylose [(d1/[η]2)/dt = k] is proportional to the square of the degree of oxidation. That is, the hydroxyl ion hydrolysis of periodate oxyamylose occurs predominately at the site where two or more oxidized units exist side by side. A reaction mechanism is postulated to account for this slow breakdown of an isolated oxidized unit and for the fast degradation of two adjacent oxidized glucose; units. When two or more oxidized units exist side by side, the free aldehyde at carbon atom 3 is believed to be in equilibrium with a hydrate instead of a hemiacetal structure as in the case of a single, isolated, oxyglucose unit in amylose. The greater reversibility of the hydrate to the free aldehyde structure results in a greater possibility of β‐alkoxycarbonyl elimination at sites where two or more oxidized glucose units exist side by side.
A polynucleotide helix containing polinosinic acid and protoated polycytidylic acid
Authors: Giannoni Giovanni , Rich Alexander 
Published: December 2004

AbstractTitration studies of the 1 : 1 helical polynucleotide complex of polyinosinic acid and polycytidylic acid reveal that these two polymers form a complex when the polycytidylic acid is protonated near pH 3. Sedimentation studies show that the protonated complex also has a 1 : 1 stoichiometry. However, the protonated complex is more stable than the unprotonated neutral complex as judged by its thermal stability. The molecular structure of the protonated complex is not the same as the neutral form. Study of the kinetics of the reaction of the protonated complex with formaldehyde suggests that the amino group of cytosine is involved in hydrogen bonds which hold the polynucleotide strands together.
The dynamics of the helix‐coil transition in poly‐α, L‐glutamic acid
Authors: Lumry R. , Legare R. , Miller W. G. 
Published: December 2004

AbstractTemperature jump measurements employing optical rotation to follow transients show an upper limit of 10μsec. on the half time of the helix‐random coil relaxation in poly‐α, L‐glutamic acid. No relaxations are observed under conditions where the polymer exists in completely helical or completely random coil form. Assuming that the helix‐coil transition can be described kinetically as a pure growth process, expressions for the relaxation time are derived for three special cases. A comparison is made between the rate of the helix‐coil transition and the rate of imide proton exchange.
Statistical mechanics of noncovalent bonds in polyamino acids. IX. The two‐state theory of protein denaturation
Authors: Poland Douglas C. , Scheraga Harold A. 
Published: December 2004

AbstractThe two‐state theory of protein denaturation, in which it is assumed that a protein exists as two species, native and denatured, is examined by three approaches in this paper. First, the point is made that denaturation of an isolated molecule involves a continuous shift in the probabilities of occurrence of many states generated by the partition function for the protein. It is argued that the maximum term approximation does not lead to a two‐state mechanism of denaturation, and that the extent of cooperation implied by the two‐state theory should give very much sharper transitions than are actually found in proteins. Second, the two‐state theory is applied to the various model systems treated in this series of papers, and is found to be inadequate. Since the detailed behaviour of the models is known, it is possible to deduce the effect of the incorrect application of the two‐state theory to a system that “denatures” by gradual unwinding. This exercise is useful when, thirdly, we examine experimental data that seem to depart radically from a two‐state interpretation. We conclude that a mechanism of gradual unwinding is the most generally valid assumption, and that the two‐state theory has no theoretical or experimental support.
Interaction between proteins and salt solutions. I. Thermodynamic parameters of dilution for gelatin and collagen
Authors: Rajagh L. V. , Puett D. , Ciferri A. 
Published: December 2004

AbstractIntrinsic viscosity–temperature studies for isoelectric gelatin in KCl and KSCN aqueous solutions and equilibrium degree of swelling, ν−1, measurements for amorphous crosslinked rat tail tendons in the same solutions were carried out. On increasing salt concentration Cs, both [η] and ν−1 increase, go through a maximum, and then decrease at high Cs, KCl being more effective than KSCN in bringing about this decrease. The trend observed is similar to the variation of solubility of polypeptides and soluble proteins with Cs. By regarding a water–salt solution of a given Cs as a single diluent interacting with the protein modified by solvation and binding of ions, usual polymer solution theories were applied to the experimental results. Thus, quantities related to the entropy and enthalpy components of the excess chemical potential of the diluents were obtained. The data indicate that the initial increase of [η] and ν−1 with Cs results from the balance of an enthalpy component which, on increasing Cs, becomes less favorable to dilution and an entropy component which, conversely, becomes more favorable. The subsequent decrease of [η] and ν−1 with Cs is due to the prevailing of the enthalpy component. The maximum is reached at higher Cs for KSCN than for KCl, primarily because of the large increase in the entropy component operated by the former salt. The increase of the entropy parameter with Cs is associated to a breaking down of the coordinated water structure and to an alteration of the conformation of the macro molecules due to ion–dipole interaction and to ion absorption. The decrease in exothermicity of dilution with Cs indicates a reduced thermodynamic affinity of the diluent toward the polymer which probably results from alteration of the nature of both polymer and diluent.
Influence of counterion radius on the polyelectrolyte behavior of synthetic polypeptide solutions
Authors: Botré C. , Solinas M. , Ascoli F. 
Published: December 2004

AbstractThe influence of counterion radius on the polyelectrolyte behavior of poly‐L‐cysteate in aqueous solution under different conditions was investigated. A linear relationship was found between a critical concentration in solution of the synthetic charged poly‐peptide and the crystallographic radius of different counterions, indicating that the stability of this macromolecule is inversely proportional to the size of the cations.
Rendement quantique, temps de vie de fluorescence et heterogeneité des sites de fixation de la proflavine sur le DNA
Authors: Weill G. 
Published: December 2004

AbstractThe binding of Acridine Orange (AO) to DNA at a phosphorus:dye molar ratio higher than 60 results in an increase of the quantum yield of fluorescence of the bound dye with respect to the free dye. The binding of proflavine (Pro) under the same conditions results, on the contrary, in a large decrease of quantum yield. This difference is surprising in view of the common increase of quantum yield of Acridine Orange and proflavine on going from aqueous to glycerol solution, the latter being a solvent with higher viscosity and lower dielectric constant. A comparative study of the spectra, lifetime of fluorescence τ, and quantum yield of fluorescence ϕ of the free and bound dye can shed light on this specific interaction and discriminate between a uniform exaltation or quenching of the dye molecules and a heterogeneity in the binding sites. For AO, the ratio τ/ϕτ0, where τ0 is the “natural” lifetime calculated from absorption spectra, remains constant for free and bound dye, a test for uniform exaltation. For proflavine, τ remains constant (4.4 ± 0.4 × 10−9 sec.), while ϕ drops from 0.7 to 0.23. This result shows that two molecules out of three are bound on a site producing almost complete quenching while the third exhibits “normal” fluorescence, comparable to that of the free dye. It is suggested that intercalation between two adenine thymine base pairs could account for the quenching. Fluorescence techniques would be valuable to study the equilibrium between the binding sites as a function of ionic strength and DNA base composition. By taking advantage of the accuracy of the lifetime determination by a photon‐sampling technique, comparison of τ for direct and sensitized excitation of fluorescence of the bound dye has been performed. No difference has been observed, which indicates a transfer time faster than 0.1 × 10−9 sec., a result in agreement with singlet singlet transfer and with the very low quantum yield of fluorescence of DNA alone at room temperature.
Effect of temperature on the spin‐lattice relaxation times of aqueous solutions of ribonuclease and human serum albumin
Authors: Blears D. J. , Danyluk S. S. 
Published: December 2004

AbstractAqueous solutions of ribonuclease and human serum albumin were subjected to periods of controlled heating and the nuclear magnetic spin‐lattice relaxation times, T1, of the water protons measured. The heat treatment causes an initial increase in the relaxation times of the water protons. These T1 variations indicate that a configurational change, compatible with a disordering of the protein structure occurs, which involves an increase in various modes of internal mobility. The T1 measurements also indicate a close, ordered association of the water molecules and the protein.