bluuebunny/crossref_metadata_2025_split huggingface dataset:
Otoplasty: a review of the surgical techniques
Authors: Richards S.D. , Jebreel A. , Capper R. 
Published: March 2005

Keypoints•  Otoplasty surgery carries a high satisfaction rate for participants (96%).•  Surgeons are more critical of the results of otoplasty than the participants or parents (92% satisfied).•  There is no statistical difference in qualitative results with different surgical techniques when comparing the published data.•  Data on otoplasty surgery is numerous, but quantitative assessment of surgical outcome is rare.•  The authors propose the measurement of cephaloauricular distance to allow comparison between studies.
How we do it: Blood contamination during management of epistaxis – awareness, utilization and availability of barrier protection
Authors: Ho E.C. , Patiar S. , Corbridge R. 
Published: March 2005

Keypoints•  There is a significant risk of blood contamination during the non‐surgical management of epistaxis. Contamination beyond gloves happens in 55% of cases1 and the contamination risk to eyes as high as 18%.2•  There is a lack of awareness and a majority of ENT doctors underestimate this risk.•  Protective barrier equipment and eye protection in particular are suboptimally available in all clinical areas where epistaxis is dealt with.•  Consequently, there is poor utilization of protective barrier equipment.
Kinetics of Enzyme Inactivation in Solution by Ionizing Radiation
Authors: Sanner T. , Pihl A. 
Published: March 2005

Equations are derived without the use of steady state assumptions for the inactivation of enzymes in dilute aqueous solution by ionizing radiation. It is shown that when the exposure times are shorter than the mean life‐time of the water radicals, as is frequently the case in experiments involving pulsed radiation, the main part of the enzyme inactivation occurs after the end of the exposure. The total inactivation under such conditions can be described by the same equation as that developed earlier for protracted irradiation. The recent claim that the absolute rate constant for the inactivation of the enzyme can be determined directly from studies of the initial part of the dose inactivation curve, is not supported by the present study.The validity of steady state approximations in the treatment of enzyme inactivation in dilute aqueous solution by ionizing radiation is examined. It is concluded that the requirements for the use of this approximation are satisfied when the exposure time exceeds greatly the life‐time of water radicals, as is the case in most enzyme experiments.
Physico‐chemical Properties of Native and Recombined Calf Thymus Nucleohistones
Authors: Fredericq E. , Houssier C. 
Published: March 2005

In the preparation of calf thymus deoxyribonucleohistone a soluble component is formed when the time of storage of the glands before extraction is too high, when high speeds of homogenization are used or when dilute solutions are too strongly stirred. Under special experimental conditions, a soluble component can be obtained which is slightly degraded in comparison with the native gel‐forming deoxyribonucleohistone, its protein content and its molecular weight being a little lower; electric birefringence and dichroism are however similar in both cases.The dissociation of deoxyribonucleohistone in concentrated salt solutions was followed by centrifugation at 100,000×g under various conditions. A progressive lowering of the protein content was found in the pellet, when the concentration varies from 0.4 to 3 M NaCl; a minimum value of 0.05 was found for the protein/DNA ratio after three centrifugations in 4 M LiCl. The analysis of the residual proteins which are undissociable from DNA shows a predominance of acidic over basic amino‐acids.Deoxyribonucleohistone dissociated in salt solutions and recombined is similar to native deoxyribonucleohistone, as regards the rigidity, the intrinsic viscosity, the melting temperature and the electro‐optical parameters. Combinations of histone and DNA display different properties.Deoxyribonucleohistone with various protein contents were prepared by centrifugation and their characteristics compared with those of native deoxyribonucleohistone. It is only for low protein/DNA ratios that most of the properties are significantly altered.The formation of gels requires a high histone content and the presence of specific proteins. The significance of gel appearance and the necessity for quantitative measurements of the modulus of rigidity have been outlined.
Ion Transport in Liver Mitochondria
Authors: Rossi C. , Azzone G. F. , Azzi A. 
Published: March 2005

The H+/Ca++ ratio during the aerobic uptake of Ca++ by rat liver mitochondria, oxidizing endogenous substrates or succinate, increased with the increase of the Ca++/protein ratio. At high protein concentrations an apparent “reuptake” of the H+ ejected was observed. Mitochondrial aging also resulted in a decrease of the H+/Ca++ ratio.Succinate caused a decrease of the H+ ejection. The effect of succinate was dependent on the pH and on the concentration of Ca++. A binding of succinate to the mitochondria was observed parallel to the decrease of the H+/Ca++ ratio from 2 to 1.Addition of Ca++ caused a release of K+ which was slow in fresh mitochondria and rapid in valinomycin treated mitochondria. The K+/Ca++ ratio was 2 in both cases.A H+/Ca++ ratio of about 2 was usually observed when the aerobic uptake of Ca++ was started either by the addition of mitochondria to a Ca++ containing medium or by the addition of succinate to Ca++‐and rotenone‐treated mitochondria.
Levels of Glycolytic Intermediates in the Musculature of the Chick during Embryonic and Post‐Embryonic Development
Authors: Arese P. , Rinaudo M. T. , Bosia A. 
Published: March 2005

Levels of glycogen and of glycolytic intermediates were assayed in quickly frozen embryonic mesodermic tissue (decapitated and eviscerated chick embryos) at the 5th and 7th developmental day and in the hind limb musculature in subsequent pre‐ and post‐natal stages. Serial determination of dry weight values during embryonic development allows conversion of the levels which are reported on a wet weight basis.While glycogen gradually increases from the 9th day onwards reaching about 1/3 of the adult amount on hatching, no substantial differences between early embryonic and adult levels were noted in the case of other intermediates, such as glucose, dihydroxyacetone‐phosphate, glyceradehyde‐3‐phosphate, 3‐ and 2‐phosphoglycerate, phosphoenolpyruvate, pyruvate and lactate. Glucose‐1‐phosphate, fructose‐6‐phosphate, glucose‐6‐phosphate and fructose‐1,6‐diphosphate were low during most of the embryonic development, attaining levels close to the adult ones only on hatching.In order to study the flow rates, the equilibrium situation at each single step and the possible control points along the glycolytic pathway, the tissue was stressed by brief periods of ischaemia or by electrical stimulation at different stages of development.Glycolytic flow rates showed a progressive increase up to hatching, where a lactate accumulation of 1.5 μmolc/min/g wet weight was measured. The maximum rate of 12.9 μmoles/min/g wet weight found in electrically stimulated muscle of hatching chicks, is well below the adult value of 52.7 μmoles/min/g wet weight.The approximate stoichiometric correspondence between glucose + glycogen breakdown and lactate formation, found to exist in the early and late embryonic stages, is absent on the 7th and incomplete on the 11th day, where the sharply reduced gluco‐ and glycogenolysis cannot account for the measured glycolytic rate. The existence of a vicarious anomalous glycolysis, supplying pyruvate and lactate by transamination or by other unknown mechanisms, is possible at these two stages.The constancy of mass‐action ratios under altered glycolytic fluxes and the comparison between the ratios in vivo and the thermodynamic equilibria show that phosphoglucomutase, phosphoglucose isomerase, aldolase, triosephosphate isomerase, phosphoglycerate mutase and enolase were maintained either at equilibrium or fairly close to equilibrium. Owing to the probable compartmentation of ATP and ADP in muscle, no calculation of kinase‐catalyzed reactions was attempted.Activation of glycolysis could not be observed on electrical stimulation of embryonic muscle at the 14th day, as the constancy of such indicator metabolites as glucose‐6‐phosphate, fructose‐1,6‐diphosphate and lactate demonstrates. An activation at the phosphorylase and phosphofructokinase steps has been indirectly shown on hatching.
Synthesis, Characterization and Enzymatic Properties of Poly‐l‐Lysyl Ribonuclease
Authors: Frensdorff A. , Sela M. 
Published: March 2005

Poly‐l‐lysyl RNase was prepared by the reaction of RNase with ɛ, N‐trifluoroacetyl‐α, N‐carboxy‐l‐lysine anhydride, either in dioxane‐aqueous phosphate buffer or in dimethylformamide in the absence of phosphate. The trifluoroacetyl group was subsequently removed from poly‐trifluoroacetyllysy RNase by 1.0 M aqueous piperidine. Derivatives prepared in aqueous media and enriched with up to 70 lysine residues, and derivatives prepared in dimethylformamide enriched with up to 270 lysine residues, were soluble and retained some activity. This activity could be completely recovered in all preparations after reduction of the disulfide bonds, followed by reoxidation. Approximately four phenolic hydroxyl groups were found, by spectrophoto‐metric titration, to ionise normally in polylysyl RNase, as opposed to three in the native enzyme.The enzymic activity of polytrifluoroacetyllysyl RNase, both on RNA and on cytidine 2′,3′‐cyclic phosphate, under various conditions, was essentially identical to that of polyalanyl RNase. Polylysyl RNase, in which the amino groups of the attached lysine peptides are unblocked and protonated, is active on RNA as well as on cytidine 2′,3′‐cyclic phosphate, but optimal activity is obtained under conditions different from those of the native enzyme. Thus polylysyl RNase displays maximal activity on RNA at ionic strength 0.6–0.7. The optimum pH for activity depends on ionic strength and is shifted at low ionic strength in the same direction as that of the isoelectric point of the modified enzyme for both RNA and cytidine cyclic phosphate. The base specificity of the modified enzyme was not significantly modified.The changes in ionic strength and pH dependence of activity are related directly to the lysine peptides attached to the enzyme and can be reversed by either reblocking the free amino groups or by removing the peptides with trypsin. Kinetic analyses suggest that the changes in activity are a result of modified substrate binding.
Regulation of the Enzymes of the β‐Ketoadipate Pathway in Moraxella calcoacetica
Authors: Cánovas J. L. , Stanier R. Y. 
Published: March 2005

The inducible enzymes responsible for the dissimilation of aromatic compounds through the β‐ketoadipate pathway by Moraxella calcoacetica are subject to a high degree of coordinate control. The five enzymes which catalyze the conversion of protocatechuate to β‐ketoadipyl‐CoA are coordinately synthesized, the probable inducer being protocatechuate. In the conversion of catechol to β‐ketoadipyl‐CoA, there are two separate inductive events, though both are mediated by one metabolite‐inducer, cis,cis‐muconate. One is the induction of catechol oxygenase; the other is the coordinate induction of the four enzymes that catalyze conversion of cic,cis‐muconate to β‐ketoadipyl‐CoA.Although the catechol and protocatechuate branches of the β‐ketoadipate pathway converge metabolically with the formation of β‐ketoadipate enol‐lactone, the two step‐reactions required for the conversion of this intermediate to β‐ketoadipyl‐CoA are mediated by two isofunctional sets of inducible enzymes, one controlled coordinately with enzymes mediating steps specific to the catechol branch, the other coordinately with enzymes mediating steps specific to the protocatechuate branch.The differing control mechanisms which govern synthesis of the enzymes of the β‐ketoadipate pathway in Moraxella calcoacetica and in Pseudomonas putida are compared and discussed.
Radical Transfer Reactions and Chemical Protection in the Dry State. Electron Spin Resonance Studies on Irradiated Mixtures of Ribonuclease and Glycyl‐Glycine
Authors: Copeland E. S. , Sanner T. , Pihl A. 
Published: March 2005

Molecular mixtures containing different proportions of ribonuclease and glycyl‐glycine were irradiated with X‐rays at 77° K and the electron spin resonance spectra were observed at this temperature and after heat‐treatment for 10 minutes at 60°.In mixtures freeze‐dried from pH 8 the number of unpaired spins observed at 77° K corresponded to the weighted average of the yields for the components. In contrast, in mixtures freeze‐dried from solutions at pH 4.4 the number of unpaired spins was much higher than expected. The qualitative spectra indicated that these “excess radicals” were located on glycyl‐glycine.The results obtained after heat‐treatment indicated that in the samples freeze‐dried from pH 8 a considerable transfer of spins occurred from RNase to glycyl‐glycine during the heat‐treatments, whereas in the samples freeze‐dried from pH 4.4 little or no additional transfer seemed to occur.The results indicate that the number of “excess radicals” at 77°K, as well as the extent of interaction in the mixtures which occurred upon heat‐treatment, depended on the state of the dissociable groups of the constituents. The finding of “excess radicals” at 77° K is tentatively attributed to the action of H atoms ejected from RNase. These H˙ atoms are assumed to interact with glycyl‐glycine to form stable radicals, while in the absence of glycyl‐glycine they are assumed to disappear primarily in combination reactions.
An Evaluation of the Mitchell Hypothesis of Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation
Authors: Slater E. C. 
Published: March 2005

The Mitchell hypothesis of chemiosmotic coupling in oxidative phosphorylation is examined in the light of experimental data on oxidative phosphorylation at present available. The following objections are brought against the theory:

Data on the magnitude of the phosphate potential against which ATP can be synthesized by the respiratory chain require, on the basis of chemiosmotic coupling, very effective proton and/or cation extrusion and/or anion uptake by the mitochondria. Experimental evidence for this is lacking. Indeed it has been shown by Chance and Mela that mitochondria in the controlled state do not extrude protons.
Although reversible ATP‐driven proton (chloroplasts) or cation (mitochondria, erythrocytes) pumps have been demonstrated, this is insufficient evidence for the postulate that the establishment of a proton gradient is the primary energy‐conserving event of the chloroplast or mitochondrial respiratory chain. Indeed, it is general experience that cations are required for the extrusion of protons by mitochondria.
The stoicheiometry of proton extrusion by mitochondria and of proton uptake by chloroplasts, and the kinetics of the latter process are also difficult to reconcile with the chemiosmotic hypothesis.
Further experimental evidence is presented confirming that, under the conditions of the oxygen‐pulse experiments of Mitchell and Moyle, the extrusion of H+ is not associated with the oxidation of mitochondrial NADH.
The respiratory chain included in the chemiosmotic hypothesis is difficult to reconcile with our present knowledge of the chain.

It is concluded that the chemiosmotic theory, in its present form, is untenable.
Differences between the Chemical Structures of Duck and Hen Egg‐white Lysozymes
Authors: Jollès J. , Hermann J. , Niemann B. , Jollès P. 
Published: March 2005

Histidine‐free duck egg‐white lysozyme III and hen egg‐white lysozyme have similar but not identical structures. some structural differences are reported.The N‐ and C‐terminal sequences are different.The unique histidine and two phenylalanine residues of hen lysozyme are replaced by a leucine and two tyrosine residues, respectively.The more basic character of duck lysozyme III is due to additional arginine residues.Duck egg‐white lysozymes II and III have not entirely identical chemical structures.
Sequenzanalyse von Oligonucleotiden mit Hilfe von Micrococcus‐Nuclease
Authors: Feldmann H. 
Published: March 2005

Micrococcal nuclease has been used in determination of oligonucleotide sequences. In order to study the mode of splitting of this enzyme in more detail, seven oligonucleotides of known sequences were digested under varying conditions.The splitting patterns obtained from the tetranucleotides CpCpCpG, ApApApG and ApΨpUpI, the pentanucleotides UpCpCpUpG, CpUpUpUpG, and UH2pUH2pApApG, and the heptanucleotide CpApApCpUpUpG were determined by analysis of the degradation products. The digestions were carried out with a crystalline sample of the enzyme. The results agree with and extend earlier observations with non‐crystalline fractions of micrococcal nuclease.A comparison of the splitting patterns leads to some generalizations: from all oligonucleotides investigated so far, the 3′‐terminal dinucleoside phosphate and the 5′‐terminal dinucleoside diphosphate were released under appropriate conditions. Tetranucleotides were split preferentially in the middle, pentanucleotides as to give mainly the dinucleotides and the middle mononucleotides. The digestion of longer oligonucleotides gave more complicated splitting patterns. The information obtained from the analyses was sufficient to reconstruct the nucleotide sequences in all cases.Micrococcal nuclease digestion as described here should be a generally applicable method for the sequence determination of oligonucleotides.
La maltodextrine phosphorylase d' Escherichia coli
Authors: Schwartz M. , Hofnung M. 
Published: March 2005

Purification of the polysaccharide phosphorylase which is induced by maltose in Escherichia coli is described. A forty five‐fold purification is achieved by heating, two ammonium sulfate precipitations and chromatography on DEAE‐cellulose. Purified preparations are essentially homogenous on DEAE‐cellulose, by electrophoresis on polyacrylamide gels and by sedimentation in the ultracentrifuge.The sedimentation coefficient s25,w of the enzyme is equal to 8 Svedberg units by sucrose gradient centrifugation and by ultracentrifugation at various protein concentations. The diffusion constant D25,w determined by the synthetic boundary technique, is 5,5 × 10−7 cm2× sec−1. The molecular weight which is derived from s25,w and D25,w (130,000) is in good agreement with that obtained by sedimentation equilibrium (140,000).The absorption spectrum of the purified enzyme has a shoulder around 330 mμ, which suggests the presence of bound pyridoxal phosphate as has also been found in polysaccharide phosphorylases obtained from various sources.The coenzyme is further identified in the present study by its high reactivity towards phenylhydrazine in perchloric acid supernatants of the enzyme. Based on the assumption that the specific molecular extinction of bound PLP is similar in all polysaccharide phosphorylases, a PLP/protein ratio of 1 mole/147,000 g can be derived from the absorbance of phosphorylase solutions at 333 mμ. The direct estimation of the quantity of PLP released in perchloric acid supernatants gives 1 mole/142,000 g.These results indicate the presence of 1 mole of PLP per mole of protein and suggest that maltodextrin phosphorylase is a monomeric enzyme.Enzyme stability, pH optimum and affinity for inorganic phosphate have been studied. Short, linear, α(1 → 4) linked oligoglucosides are very active substrates, whereas polyglucosides of high molecular weight (glycogen, starch) are much less active. The shortest maltodextrin which can readily be phosphorolysed is maltopentaose.The maltodextrin phosphorylase of Escherichia coli appears to be similar to animal and plant polysaccharide phosphorylases in several of its enzymatic properties. Furthermore, a point of striking similarity is the presence of bound PLP.The bacterial enzyme has two distinctive properties: one is its specificity for small oligoglucosides and the other is its monomeric structure.
Mechanism of the Action of Chelating Agents on Proline Hydroxylation and its Incorporation into Collagenous and non‐Collagenous Proteins
Authors: Chvapil M. , Hurych J. , Ehrlichová E. , Tich M. 
Published: March 2005

The effect of concentration of some chelating agents on proline hydroxylation and the synthesis of collagenous and non‐collagenous proteins was studied in skin slices of chick embryo. In a group of eight chelating agents a good correlation was found between the degree of inhibition of hydroxylation and the stability constant of ferrous chelates. No correlation with the stability of cupric complexes was found. The failure of 2,9‐dimethyl‐1,10‐phenanthroline to inhibit hydroxylation also suggests participation of Fe2+. The study of the influence of different times of preincubation of the tissue with chelating agents showed that 2,2′‐dipyridyl and 1,10‐phenanthroline inhibit the hydroxylation of proline already within 10 minutes. In addition 2,2′‐dipyridyl and in 1 mM concentration also inhibits after 2 hours of action the incoporation of [14C]proline into collagenous proteins and does not change during a 4 hour incubation the synthesis of non‐collagenous proteins. Phenanthroline, in the same concentration, inhibits already during the first 60 minutes of incubation both the synthesis of collagen as well as of non‐collagenous proteins. Chelating agents which do not penetrate cell membrane are without effect on the reactions studied.The blockade of hydroxylation is a specific result of the chelation of bivalent iron. Chelating agents influence more easily the incorporation of amino acids into collagenous proteins than synthesis of globular proteins. This effect is considered specific because it is related to the chelating properties of the substances investigated. All other investigated substances without chelating properties inhibit, according to the concentration used, synthesis of both types of protein equally, so that the decrease in hydroxyproline formation is secondary to the inhibition of proline incorporation. Close correlation between the inhibition of protein synthesis and general toxicity of these substances has been found.