bluuebunny/crossref_metadata_2025 huggingface dataset:
The effectiveness of the Peyton’s 4-step teaching approach on skill acquisition of procedures in health professions education: A systematic review and meta-analysis with integrated meta-regression
Authors: Giacomino Katia , Caliesch Rahel , Sattelmayer Karl Martin
Published: October 2020

Background

Acquisition of procedures is an important element in health professions education. Traditionally procedures are taught using a “see one - do one” approach. That is a teacher demonstrates and describes a procedure and afterwards the students practice the procedure. A more recent teaching approach for the acquisition of procedural skills was presented by Walker and Peyton. Peyton’s teaching approach is a stepwise teaching approach and consists of the following four steps: demonstration, deconstruction, comprehension and performance. The aims of this study were (i) to systematically evaluate the effectiveness of Peyton’s 4–step teaching approach on the acquisition of procedural skills in health professions education and (ii) to evaluate whether studies with fewer students per teacher showed a larger between group difference than studies with more students per teacher.

Methods

We searched in Medline, PsycInfo, Embase and ERIC for eligible studies. Records were screened by two independent reviewers. A random effects meta-analysis was performed to evaluate skill acquisition and time needed to perform the procedures at post-acquisition and retention tests. A meta-regression was used to explore the effect of the number of students per teacher on the estimated effect of the educational interventions.

Results

An effect size of 0.45 SMD (95% CI [0.15; 0.75]) at post-acquisition and 0.7 SMD (95% CI [−0.09; 1.49]) at retention testing were in favour of Peyton’s teaching approach for skill acquisition. The groups using Peyton’s teaching approach needed considerably less time to perform the procedure at post-acquisition (SMD: −0.8; 95% [CI −2.13 to 1.62]) and retention (SMD: −2.65; 95% CI [−7.77 to 2.47]) testing. The effectiveness of Peyton’s teaching approach was less clear in subgroup analyses using peer teachers. Meta-regression showed that the number of students per teacher was an important moderator variable.

Conclusion

Peyton’s teaching approach is an effective teaching approach for skill acquisition of procedural skills in health professions education. When peer students or student tutors are used as teachers the effectiveness of Peyton’s teaching approach is less clear. Peyton’s teaching approach is more effective when small groups with few students per teacher are used.
Synthesis, Characterisation and Antimicrobial Studies of Schiff Base and Its Metal Complexes
Authors: Abdulsayid Fatimah A. , Hasan Hamad M. Adress , Bouagila Roaa A.
Published: October 2020

Four metal complexes of Co(II), Pb(II),  Ni(II) and Fe(II) ions with a Schiff base derived from (3-methoxy-4-hydroxy-benzaldehyde with leucine) have been synthesized and characterized using several physical techniques, in particular; molar conductance measurements, colour, melting point,  infrared and electronic spectra. The molar conductance values reveal a non-electrolytic nature. The infrared spectral data display the coordination behaviour of the Schiff base toward Co(ll) ,pb(ll) ,Ni(ll) and Fe(ll) ions. The electronic absorption spectra of the Schiff base and its complexes show π→π* (phenyl ring) and, n→π* (HC=N) and the expected geometrical structure for the prepared complexes. The Schiff base and its complexes were tested for antimicrobial activity against gram-positive bacteria; Staphylococcus aurous; E. Coli and Klebsiella, in addition Rizopus as fungal. The effect of the Schiff base leucine complex on bacteria was recorded only against Staphylococcus aureus and Escherichia coli.
Production, Preservation and Shelf-Life Evaluation of Wine from Banana Fruit (Musa acuminata Colla)
Authors: Obiekezie O. P. , Efiuvwevwere B. J. O. , Eruteya O. C.
Published: October 2020

Aims: The investigation focused on production, preservation and shelf-life study of wine from banana fruit (Musa acuminata).

Study Design: This work is based on completely randomized design with two replications and the average values calculated for mean comparison.

Place and Duration of Study: Food and Industrial Microbiology laboratory, Department of Microbiology, University of Port Harcourt, Nigeria, September, 2018 to March, 2019.

Methodology: Analyses performed using standard methods were microbiological, physicochemical and sensory evaluations. Sodium benzoate concentrations of 5 and 25 ppm were used for shelf life studies. Banana ‘must’ was analyzed at 4 day intervals for 12 days while produced wine was analyzed at 5 day intervals for 25 days during storage.

Results: Changes in total heterotrophic counts (THCs), total coliform counts (TCCs) and fungal counts (FCs) occurred during fermentation, resulting in maximum THCs of 5.02, TCCs of 3.60 and FCs of 8.87 log10 cfu ml-1 on days 4, 4 and 8 respectively. Acetobacter and Saccharomyces were pronounced in wine without preservative (control) throughout storage. Mean pH of ‘must’ was 5.8±0.30 while alcohol content was 0.28±0.03% on day 0 but as fermentation progressed, mean pH was reduced while mean alcohol content increased. Mean pH of wine preserved with 5 ppm varied slightly throughout storage but mean pH of control and 25 ppm preserved wine decreased from 3.7±0.20 on day 0 to 3.2±0.23 on day 25. Sensory attributes (overall acceptability) on day 12 was most preferred while during shelf-life studies, significant difference in overall acceptability of the different wines at P=.05 occurred. Wine preserved with 5 ppm had the best organoleptic quality but 25 ppm preserved wine showed the most acceptable microbial quality.

Conclusion: Findings show that banana is a good substrate for wine production and 5 ppm sodium benzoate retained the qualities of the wine.
Particules ribonucleoproteiques 40 s des noyaux de foie de rat. Proprietes des proteines de ces particules
Authors: Sarasin Alain
Published: July 2002

Rat liver 40 S ribonucleoprotein particles, which are different from ribosomal subparticles, were isolated and the protein moiety studied. Disc electrophoresis at pH 4.5 and 8.8 suggests that these particles have a relatively simple protein structure, the proteins having isoelectric points which are near neutrality or slightly acidic. The amino acid composition shows an acidic residue/basic residue ratio of 1/1.39 and an as yet unidentified ninhydrin‐positive compound which is probably specific to these 40 S particles.
Purification of lactose synthetase a protein from human milk and demonstration of its interaction with α‐lactalbumin
Authors: Andrews P.
Published: July 2002

A fairly simple procedure for isolating lactose synthetase A protein from human milk in 36% yield is described. The A protein has a molecular weight of about 40,000. Its interaction with α‐lactalbumin in the presence of N‐acetylglucosamine has been demonstrated by affinity chromatography and gel filtration.
Monoclonal antibodies against human low density lipoprotein
Authors: Milne Ross W. , Marcel Yves L.
Published: July 2002

Because of its physical properties, apolioprotein B (apo B) has remained poorly characterized. In an attempt to elucidate apo B structure, the Fab fragments of 3 different monoclonal anti‐human apo B anti‐bodies were tested in a quantitative assay for their binding to human low density lipoprotein (LDL). In each case the assay gave a linear Scatchard plot with a maximum of 1 Fab fragment bound to a single LDL particle. This result favors an LDL model containing a single large M
r apo B protein, which is not composed of multiple, identical, small M
r subunits.
On the mechanism of biosynthesis of leukotrienes and related compounds
Authors: Panossian Alexander , Hamberg Mats , Samuelsson Bengt
Published: July 2002

[10D‐3H; 3‐14C]‐ and [10L‐3H; 3‐14C]arachidonic acids were incubated with human polymorphonuclear leukocytes and with human platelets. Leukotriene B4 and 5(S),12(S)‐dihydroxy‐6trans,8cis,10trans,14‐cis‐eicosatetraenoic acid (5,12‐DHETE) were isolated and the 3H/14C ratios determined. It could be concluded that the 10D (pro‐R)‐hydrogen is eliminated in the conversion of 5(S)‐hydroperoxy‐6trans,8cis,11cis,14cis‐eicosatetraenoic acid into leukotriene A4 whereas in the conversion of arachidonic acid into 5,12‐DHETE the 10L (pro‐S)‐hydrogen is lost. Incubation of the doubly labeled arachidonic acids with human platelets confirmed and extended previous data on the stereochemistry of the hydrogen removal from C‐10 during the conversion into 12(S)‐hydroperoxy‐5cis,8cis,10trans,14cis‐eicosatetraenoic acid, i.e., the 10L (pro‐S)‐hydrogen is eliminated and the 10D (pro‐R)‐hydrogen retained.
Carbodiimide‐induced protein—RNA crosslinking in mammalian ribosomal subunits
Authors: Buisson M. , Reboud A.M.
Published: July 2002

RNA—protein interactions in the 60 S subunits of rat liver ribosomes were studied using 1‐ethyl‐3‐dimethylaminopropyl carbodiimide (EDC) under conditions which neither changed the sedimentation coefficient of subunits nor the intactness of their rRNA. EDC induced RNA—protein and protein—protein crosslinkings. Proteins crosslinked to 28 S RNA were identified by two‐dimensional gel electrophoreses as L17, L19, L23a and L37a, shown to react with 28 S RNA when using a low dose of UV radiation. Attempts have also been made to use EDC for the studies of RNA—protein interactions in 40 S ribosomal subunits.
Monoclonal antibodies directed to human insulin‐like growth factor I (IGF I)
Authors: Laubli Urs K. , Baier Wolfgang , Binz Hans , Celio Marco R. , Humbel René E.
Published: July 2002

Mouse hybridomas secreting antibodies to human insulin‐like growth factor I (IGF I) were produced by fusion of spleen cells of hyperimmunised mice with FO mouse‐myeloma cells. Eight clones producing antibodies against human IGF I have been isolated, two of which have been characterised. One was used in a radioimmunoassay, the other for immunopurification of IGF.
Differential proteolysis and evidence for a residue exchange in tissue plasminogen activator suggest possible association between two types of protein microheterogeneity
Authors: Jörnvall Hans , Pohl Gunnar , Bergsdorf Nils , Wallén Per
Published: July 2002

The N‐terminal part of native one‐chain tissue plasminogen activator from melanoma cells is not homogeneous. The protein chain starts at two different postions, in all probability representing a processing difference in the N‐terminus. Both ‘long’ L‐chains and 3‐residue shorter S‐chains are present in the preparations. In addition, results compatible with a positional Ser/Gly microheterogeneity were obtained at a single position (positions L‐4 which is equal to S‐1). The N‐terminal tripeptide difference seems to be coupled to the possible microheterogeneity: L‐chains contain Ser in this position, while S‐chains appear to contain predominantly Gly.
Mechanism of proton translocation associated to oxidation of N,N,N′,N′‐tetramethyl‐p‐phenylenediamine in rat liver mitochondria
Authors: Papa S. , Guerrieri F. , Izzo G. , Boffoli D.
Published: July 2002

A kinetic analysis is presented of proton translocation, TMPD+ formation and oxidation of endogenous respiratory carriers during oxygen pulses of TMPD supplemented rat‐liver mitochondria. The results show that antimycin‐insensitive proton ejection observed under coupled conditions derives from oxidation of endogenous respiratory carriers and re‐reduction of TMPD+ by hydrogenated donors and not from proton pumping by cytochrome oxidase as claimed by other investigators. The observations presented provide an example of certain interpretative difficulties in the use of redox mediators and of the methodological approaches that can be used to avoid these.
Light‐driven DNA biosynthesis in isolated pea chloroplasts
Authors: Ronald Mills W. , Baumgartner Brian J.
Published: July 2002

Isolated chloroplasts from Pisum sativum leaves catalyze [3H]thymidine incorporation into acid‐insoluble material using light as the sole energy source. Neither ribonucleotides, deoxyribonucleotides nor deoxyribonucleosides (other than [3H]thymidine) are required. However, it is necessary that the plastids be intact and photosynthetically competent, as little synthesis occurs in lysed preparations or in the presence of photophosphorylation inhibitors. Thymidine incorporation is markedly reduced by the DNA synthesis inhibitors rifampicin, nalidixic acid, ethidium bromide and N‐ethylmaleimide. Plant age is an important factor, since rates of synthesis are 3–10‐times higher in plastids isolated from young plants (6–8 days old) than in chloroplasts from older ones (9–14 days old). The maximum rates using plastids from young leaves of 60–70 pmd/mg chlorophyll/h are 30–60‐times greater than those previously reported [1].
Length of myosin rod and its proteolytic fragments determined by electron microscopy
Authors: Stewart Murray , Edwards Pat
Published: July 2002

The mean length of rabbit myosin chymotryptic rod in electron micrographs of unidirectionally shadowed preparations was 154 nm. Tryptic light meromyosin prepared from this rod had a mean length of 86 nm whereas long and short S2 measured 62 and 43 nm, respectively. The combined length of light meromyosin and long S2 appeared to be less than that of rod, which indicated that possibly some material was lost on digestion. Molecular lengths agreed with sedimentation equilibrium M
r values but were lower than those indicated by gel electrophoresis.
Oligomycin sensitivity‐conferring protein (OSCP) of beef heart mitochondria
Authors: Ovchinnikov Yu.A. , Modyanov N.N. , Grinkevich V.A. , Aldanova N.A. , Kostetsky P.V. , Trubetskaya O.E. , Hundal T. , Ernster L.
Published: July 2002

Structural analysis of oligomycin sensitivity‐conferring protein (OSCP) revealed repeating sequences (residues 1‐89, 105‐190) suggesting an evolution of the protein by gene duplication. In addition to the reported homology with the δ‐subunit of Escherichia coli F1ATPase, OSCP also shows a certain homology with the b‐subunit of E. coli F0 and the ADP/ATP carrier of mitochondria.
Light‐dependent trans to cis isomerization of the retinal in halorhodopsin
Authors: Lanyi Janos K.
Published: July 2002

Flash‐induced absorption changes in the near UV were determined for bacteriorhodopsin and halorhodopsin on a millisecond time scale. The difference spectrum obtained for bacteriorhodopsin was comparable to model difference spectra of tyrosine (aromatic OH deprotonated vs protonated), as found by others. The flash‐induced difference spectrum for halorhodopsin, in contrast, resembled a model spectrum opbtained for trans to 13‐cis isomerization of retinal in bacteriorhodopsin. A model for chloride translocation by halorhodopsin is presented, in which the retinal isomerization moves positive charges, which in turn modulate the affinity of a site to chloride.
Purification of Escherichia coli 50 S ribosomal proteins by high performance liquid chromatography
Authors: Kamp Roza Maria , Wittmann-Liebold Brigitte
Published: July 2002

The 50 S subunit proteins from the Escherichia coli ribosome were purified by size‐exclusion, ion‐exchange or reversed phase high performance liquid chromatography (HPLC) avoiding any precipitation or desalting procedures during isolation. Best resolution of this complex protein mixture was achieved by reversed phase chromatography on supports with short alkyl chains and C18 hydrocarbon‐bonded phases; 23 out of the 32 proteins from the 50 S subunit were purified as shown by two‐dimensional gel electrophoresis, amino acid analysis and direct micro‐sequencing. Protein recoveries varied between 25 and 84% as determined by amino acid analysis. Ribosomal proteins of other organims can be separated under similar conditions.
Functional reconstitution of the partially purified aspartate‐glutamate carrier from mitochondria
Authors: Krämer Reinhard
Published: July 2002

The aspartate/glutamate carrier from beef heart mitochondria has been solubilized with detergent. The transport protein was partially purified by chromatography on hydroxyapatite in the presence of dodecyl octaoxyethylene ether and high concentrations of ammonium acetate. During purification, the aspartate/ glutamate carrier was identified by functional reconstitution into egg yolk phospholipid liposomes. After hydroxyapatite chromatography the protein is 30 fold enriched in aspartate/glutamate transport activity but still contains ADP/ATP‐carrier and phosphate carrier. The reconstituted activity is specific for exchange of L‐aspartate and L‐glutamate and is similar to intact mitochondria with respect to substrate affinity and inhibitor sensitivity.
Human apolipoprotein B: partial amino acid sequence
Authors: LeBoeuf Renee C. , Miller Chad , Shively John E. , Schumaker Verne N. , Balla Maria A. , Lusis Aldons J.
Published: July 2002

A successful approach has been developed for the sequencing of apolipoprotein B based upon the procedure of Cleveland et al. [(1977) J. Biol. Chem. 252, 1102–1106] involving limited proteolysis in the presence of sodium dodecyl sulfate. Staphylococcus aureus protease was employed to produce large peptides which were isolated in relatively pure form by preparative gel electrophoresis. Two peptides were partially sequenced using spinning‐cup microsequencing techniques. The sequences are: Peptide R2‐5, ‐Ala ‐ Leu ‐ Val ‐ Gly ‐ Ile ‐ Asn ‐ Gly ‐ Glu ‐ Ala ‐ Asn ‐ Leu ‐ Asp ‐ Phe ‐ Leu ‐ Asn ‐ Ile ‐ Pro ‐ Leu ‐ Arg‐ Ile ‐ Pro‐ Pro‐Met‐Arg‐(Arg)‐; and Peptide R3‐1, ‐Leu‐Val‐Ala‐Lys‐Pro‐Ser‐Val‐Ser‐Val‐Glu‐Phe‐Val‐Thr ‐Asn‐Met‐Gly‐Ile‐Ile‐Ile‐Pro‐Lys‐Phe‐Ala‐Arg‐. Several stretches of residues suitable for the construction of oligonucleotide probes have been identified.
Action of cobra venom cardiotoxin on chick embryonal fibroblasts transformed with a temperature‐sensitive mutant of Rous sarcoma virus
Authors: Kaneda Norio , Hamaguchi Michinari , Kojima Kiyohide , Kaneshima Hideto , Hayashi Kyozo
Published: July 2002

The cytolytic action of cardiotoxin analogue III from the venom of the Formosan cobra on chick embryonal fibroblasts transformed with a temperature‐sensitive mutant of Rous sarcoma virus was investigated. The 50% effective dose of the toxin for the cells cultured at a non‐permissive temperature (41°C) or for noninfected normal cells was about 8 whereas the value was 2 for the cells cultured at a permissive temperature (36°C). This indicates that the transformed cells became more susceptible to the cytolytic action of the toxin than the non‐transformed cells.
Protective effect of the flavonoid silybin dihemisuccinate on the toxicity of phenylhydrazine on rat liver
Authors: Valenzuela Alfonso , Guerra Ricardo
Published: July 2002

Phenylhydrazine is a hemolytic agent whose mechanism of action is related with the formation of free radicals and the induction of lipid peroxidation. The flavonoid silybin dihemisuccinate is an antihepatotoxic principle used in the treatment of many liver diseases; its mechanism of action has been ascribed to its antioxidant properties. This work demonstrates, using a hemoglobin‐free perfusion system, the protective effect of the in vivo treatment of the rat with silybin dihemisuccinate on the hepatic glutathione depletion and lipid peroxidation induced by the infusion of phenylhydrazine into the perfusion buffer.
A somatic cell mutant with a kinetically altered 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase
Authors: Sinensky Michael , Logel Judy , Schnitzer-Polokoff Robin , Norcross Rae Ann
Published: July 2002

A somatic cell mutant has been isolated which is resistant to killing and growth inhibition by mevinolin, a competitive inhibitor of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase. The resistance phenotype is dominant with respect to the wild‐type cell and can largely be ascribed to a 6–7‐fold lowering of the K
M for HMG‐CoA. We thus conclude that mevinolin resistance can be utilized to obtain a genetic marker for the structural gene encoding HMH‐CoA reductase.
Phosphorylation of HMG‐CoA reductase induced by mevalonate accelerates its rate of degradation in isolated rat hepatocytes
Authors: Marrero Pedro F. , Haro Diego , Hegardt Fausto G.
Published: July 2002

Incubation of rat hepatocytes with 10 mM mevalonate produces a decrease in HMG‐CoA reductase activity and in the rate of synthesis of both monomeric and dimeric HMG‐CoA reductase, and an increase in the rate of degradation of the monomeric form without significant change in that of the dimeric form. Since mevalonate promotes a short‐term phosphorylation of the monomeric form without affecting the dimeric form, it is suggested that the mechanism of degradation of reductase is controlled by its phosphorylation state.
Evidence for ADP‐ribosylation in the mechanism of rapid thyroid hormone control of mitochondria
Authors: Thomas Wendy E. , Mowbray John
Published: July 2002

Triiodothyronine in vitro at concentrations between 10−13 and 1O−11M very rapidly activates oxidative phosphorylation in hypothyroid rat liver mitochondria. Comparing the concentrations of hormone with estimates of the amounts of respiratory chain components present suggests that this activation may involve an amplification mechanism. Here we present evidence that while no changes in phosphorylation were detected following hormone administration, nicotinamide, an inhibitor of mono ADP‐ribosylation reported to occur rapidly and reversibly in mitochondria, prevented activation by hormone. Moreover incubation with nicotinamide of euthyroid mitochondria and derived intact inner membrane vesicles revealed lowered ADP/O ratios under the same conditions as shown by hypothyroid preparations. While this lesion could be reversed simply by washing the intact mitochondria, the membrane vesicles required triiodothyronine addition.
Dithiols and monothiols are linked with GABA transport in membrane vesicles of rat brain synaptosomes
Authors: Robillard G.T. , Schaaf J.M. , Teelken A.W.
Published: July 2002

The properties of γ‐aminobutyric acid (GABA) transport into membrane vesicles derived from synaptosomes of rat brain have been studied using membrane‐permeable and ‐impermeable sulfhydryl reagents, dithiol‐specific reagents and oxidizing reagents. GABA transport is inhibited, reversibly, by very low concentrations of the membrane‐permeable trivalent arsenical, phenylarsine oxide. Preincubation with this reagent only partially protects GABA transport from inactivation by N‐ethylmaleimide (NEM). Thorin, a negatively charged trivalent arsenical, has no influence on GABA transport at concentrations 100‐fold higher than that of the inhibitory phenylarsine oxide. The impermeant oxidizing agent, potassium ferricyanide, did not inhibit transport whereas the permeant reagent, diamide, was inhibitory. These data indicate that the GABA transporter possesses an activity‐linked dithiol in a hydrophobic region of the carrier not accessible to charged, polar reagents. p‐Chloromercuribenzenesulfonate (PCMBS) also inhibits but does not protect against NEM inactivation, suggesting the occurrence of an activity‐linked monothiol in a polar region of the carrier.
2,3‐Bisphosphoglycerate inhibits ATP‐stimulated proteolysis
Authors: Roche E. , Aniento F. , Knecht E. , Grisolía S.
Published: July 2002

Intracellular protein breakdown could be regulated at the substrate level by changes in the environment. Under in vitro conditions, ATP increases the proteolytic susceptibility of several mitochondrial and cytosolic proteins, while 2,3‐bisphosphoglycerate not only has the opposite effect but also prevents the ATP‐stimulated proteolysis. ATP and 2,3‐bisphosphoglycerate, present at relatively high levels in many tissues, provide a good model of environmental components that may influence intracellular proteolysis.
Adenosine analogs with covalently attached lipids have enhanced potency at A1‐adenosine receptors
Authors: Jacobson Kenneth A. , Zimmet Jeffrey , Schulick Richard , Barone Suzanne , Daly John W. , Kirk Kenneth L.
Published: July 2002

Chemically functionalized congeners of N6‐phenyladenosine and 1,3‐dipropyl‐8‐phenylxanthine have been covalently coupled to fatty acids, diglycerides, and a phospholipid. The lipid‐drug conjugates inhibit R‐[3H]‐phenylisopropyladenosine binding to A1‐adenosine receptors in rat cerebral cortex membranes. A xanthine‐phosphatidylethanolamine conjugate bound with a K
i value of 19 nM. Various xanthine esters of low potency are potential prodrugs. Amides of an adenosine amine congener (ADAC) with 18‐carbon fatty acids exhibited K
i values at A1‐adenosine receptors of 70 pM, representing a 130‐fold enhancement over the affinity of the corresponding acetyl amide. The very high affinity of adenosine‐lipid conjugates may be due to stabilization of these adducts in the phospholipid microenvironment of the receptor protein.
Protein dynamics and distance determination by NOE measurements
Authors: LeMaster David M. , Kay Lewis E. , Brünger Axel T. , Prestegard J.H.
Published: July 2002

Present analysis procedures for NMR structure determination of macromolecules presuppose fixed internuclear distances. Improvement of the precision of the requisite NOE information has stimulated the use of more quantitative distance constraints thus necessitating examination as to whether the assumption of a rigid model systematically biases the distance estimates. Analysis using the simple <r
−6> dependence of NOE buildup rates seriously underestimates the correct distance for spatially proximal proton pairs having fluctuations comparable to those observed in X‐ray temperature factor analysis. However, by calculating the proper generalized order parameter it is shown that for nuclei undergoing rapid isotropic uncorrelated fluctuations the effective distance is identical to the distance between the mean positions of the nuclei. Similar analysis of molecular dynamics simulation data from bovine pancreatic trypsin inhibitor indicates that the distance obtained from the generalized order parameter predicts the distance between the mean positions to within a few percent regardless of the degree of correlation of the pairwise motion for virtually all main chain and dynamically constrained side chain protons.
Identification of a cysteine residue as the binding site for the dipyrromethane cofactor at the active site of Escherichia coli porphobilinogen deaminase
Authors: Jordan Peter M. , Warren Martin J. , Williams Howard J. , Stolowich Neal J. , Roessner Charles A. , Grant Stephen K. , Scott A.Ian
Published: July 2002

The dipyrromethane cofactor of Escherichia coli porphobilinogen deaminase was specifically labelled with 13C by growth of the bacteria in the presence of 5‐amino[5‐13C]levulinic acid. Using 13C‐NMR spectroscopy, the structure of the cofactor was confirmed as a dipyrromethane made up of two linked pyrrole rings each derived from porphobilinogen. The chemical shift data indicate that one of the pyrrole rings of the cofactor is covalently linked to the deaminase enzyme through a cysteine residue. Evidence from protein chemistry studies suggest that cysteine‐242 is the covalent binding site for the cofactor.
Type IX collagen: A possible function in articular cartilage
Authors: Wotton S.F. , Duance V.C. , Fryer P.R.
Published: July 2002

The effect of type IX on in vitro fibrillogenesis of type II collagen indicated that, while not preventing fibrillogenesis, the presence of type IX collagen reduced the size of the type II fibre aggregates. This observation is consistent with the in vivo localisation studies of type IX collagen. Using the immunogold labelling technique, type IX collagen was shown to be located evenly on small fibrils which occur at higher concentration closer to the cell. Therefore type IX collagen may function as a regulator of fibre diameter in articular cartilage.
A quenched‐flow study of a receptor‐triggered second messenger response: Cyclic AMP burst elicited by isoproterenol in C6 glioma cell membranes
Authors: Valeins Henri , Volker Tobias , Viratelle Odile , Labouesse Julie
Published: July 2002

Fast kinetic studies of cAMP accumulation in C6 cell membranes show a burst of cAMP after β‐adrenergic receptor stimulation by isoproterenol. This burst is no longer observed when the ATP present in membrane preparations is hydrolyzed, but can be restored by their preincubation in the presence of ATP‐Mg. The size of the burst is much larger than the number of β‐adrenergic receptors and is of the same order of magnitude as the value reported for G proteins. Further characterization of the burst will allow studies of the functional interaction of receptor‐adenylate cyclase components in C6 membranes.
Isolation and reconstitution of the high‐affinity choline carrier
Authors: Knipper M. , Boekhoff I. , Breer H.
Published: July 2002

Monoclonal antibodies, which block the high‐affinity uptake of choline in synaptosomal ghosts, have been used to purify a membrane polypeptide (80 kDa) from insect synaptosomal membranes. This isolated protein was found to catalyse the sodium‐dependent, hemicholinium‐sensitive accumulation of choline after reconstitution into liposomes, thus, apparently represents the high‐affinity choline transporter.
Circular dichroism and fluorescence studies on five mutant forms of protein synthesis initiation factor eIF‐4E, from the yeast Saccharomyces cerevisiae
Authors: McCubbin William D. , Edery Isaac , Altmann Michael , Sonenberg Nahum , Kay Cyril M.
Published: July 2002

CD studies have shown that five tryptophan to phenylalanine (W→F) mutants of eukaryotic initiation factor‐4E (eIF‐4E) contain low amounts of α‐helix, the main elements of secondary structure being β‐sheets/turns and aperiodic regions. Interactions with the cap analog m7GpppG are accompanied by changes in overall secondary structure which include reductions, and in one case an increase in α‐helix content, as well as increases in total β‐structure (3 mutant forms) and decreases in total β‐structure (2 mutant forms). These changes may also involve more significant perturbations of localized regions containing phenylalanine residues either involved in nucleotide binding, or close to the nucleotide‐binding site. Measurements of intrinsic Trp fluorescence have shown different quantum yields and reduced m7GpppG‐induced quenching (with one exception). Acrylamide quenching studies yielded similar parameters for 4 of the mutants but 1 form displayed significantly reduced values. Melting experiments showed that the Trp fluorescence of 4 of the mutants decreased as the temperature was increased, this effect being reduced in 3 cases in the presence of m7GpppG. W 58 F showed an increase in fluorescence as the temperature was raised and this effect was accentuated in the presence of nucleotide. A preliminary attempt has been made to correlate the spectroscopic data with the known biological importance of the individual Trp residues.
Purification and characterization of the Ner repressor of bacteriophage Mu
Authors: Kukolj George , Tolias Peter P. , DuBow Michael S.
Published: July 2002

The Ner protein of bacteriophage Mu acts as a λ cro‐like negative regulator of the phage's early (transposase) operon. Using the band retardation assay to monitor ner‐operator‐specific DNA‐binding activity, the 8 kDa Ner protein was purified to homogeneity. DNase I footprinting revealed that the purified protein bound and protected a specific DNA operator that contains two 12 bp sites with the consensus sequence 5′‐ANPyTAPuCTAAGT‐3′, separated by a 6 bp spacer region. Moreover, regions corresponding to a turn of the DNA helix flanking these 12 bp repeats are also protected by Ner. Unlike the functionally similar λ cro protein, gel filtration experiments show the native molecular mass of Mu Ner to be approx. 8 kDa. These results, plus the pattern of DNase I protection, suggest that the protein may bind as a monomer to each of its specific DNA substrates.
Two components of type III protein kinase C with different substrate specificities and a phospholipid‐dependent but Ca2+‐inhibited protein kinase in rat brain
Authors: Buday Lázló , Mészáros György , Farkas Gyöngyi , Seprődi János , Antoni Ferenc , Faragó Anna
Published: July 2002

The activities of rat brain protein kinase C isoenzymic fractions separated by hydroxyapatite chromatography were measured with histone H1 or the oligopeptide Ala‐Ala‐Ala‐Ser‐Phe‐Lys‐Ala‐Lys‐Lys‐amide as substrates. The oligopeptide was a better substrate than histone H1 for nearly all of the protein kinase C fractions. Two subtractions of type III isoenzyme were resolved (IIIa and IIIb); type IIIb was characterized by a very low histone kinase activity compared to its peptide kinase activity. In some brain extracts a phospholipid‐dependent but Ca2+‐inhibited protein kinase was also observed which was eluted from the hydroxyapatite column between type II and III isoenzymes of protein kinase C.
Ammonium‐dependent transports of amino acids and glucose in a facultatively anaerobic alkalophile
Authors: Koyama Noriyuki
Published: July 2002

It was found that the growth of a facultatively anaerobic alkalophile depends on the presence of NH+
4. The poor growth in the absence of NH+
4 did not seem to be ascribed to a lack of nitrogen sources. The bacterium was suggested to require specifically NH+
4 for the acceleration of transports of amino acids and glucose, which is likely to contribute to the optimum growth.
Retinoic acid controls expression of epidermal transglutaminase at the pre‐translational level
Authors: Michel Serge , Reichert Uwe , Isnard Jean Luc , Shroot Braham , Schmidt Rainer
Published: July 2002

Human epidermal keratinocytes were cultured until sub‐confluence in low Ca2+ (0.15 mM) serum‐free synthetic MCDB 153 medium. Raising the Ca2+ concentration to 1.15 mM caused an increase in envelope competence as well as plasma membrane associated transglutaminase (TGm) activity. This increase was not observed when the high Ca2+ medium contained retinoic acid. Immunofluorescence studies as well as immunoblotting with the TGm‐specific monoclonal antibody B.C1 revealed that retinoic acid inhibits expression of TGm. Isolation and in vitro translation of mRNA with subsequent immunoprecipitation showed that retinoic acid inhibits TGm expression at the pretranslational level.
EPR characterization of soluble fragments of succinate dehydrogenase from mutant strains of Bacillus subtilis
Authors: Maguire John J. , Hederstedt Lars
Published: July 2002

Succinate dehydrogenase; Iron‐sulfur cluster; Flavo‐enzyme; Metallo‐enzyme assembly
Undifferentiated HL60 cells respond to extracellular ATP and UTP by stimulating phospholipase C activation and exocytosis
Authors: Stutchfield Jane , Cockcroft Shamshad
Published: July 2002

We have recently characterised the presence of a Ca2+‐mobilising receptor for ATP which stimulates exocytosis in differentiated HL60 cells. Here we demonstrate that the Undifferentiated HL60 cells also respond to extracellular ATP by stimulating an increase in inositol phosphates and exocytosis. Of the nucleotides (ATP, UTP, ITP, ATPyS, AppNHp, XTP, CTP, GTP, 8‐Br‐ATP and GTPγS) that were active in stimulating inositol phosphate formation, only UTP, ATP, ITP, ATPγS and AppNHp were active in stimulating secretion. On differentiation, the extent of secretion due to the purinergic agonists ATP, ITP, ATPγS and AppNHp remained unchanged whilst secretion due to UTP, a pyrimidine, was substantially increased. These results indicate that the effect of ATP and UTP may be mediated via separate purinergic and pyrimidinergic receptors, respectively.
Microtubule translocation caused by three subspecies of inner‐arm dynein from Chlamydomonas flagella
Authors: Kagami Osamu , Takada Saeko , Kamiya Ritsu
Published: July 2002

To help understand the function of inner‐arm dynein in nagellar motility, dynein samples from an outer arm‐missing mutant of Chlamydomonas (odal) were examined for the ability to translocate microtubules in vitro. High‐salt extract ofaxonemes containing inner‐arm dynein was separated by ion‐exchange chromatography into 7 peak fractions with ATPase activities. Of these, three fractions containing different sets of dynein heavy chains translocated microtubules. The maximal velocities were all between 3 and 5 , which were comparable to the microtubule sliding rate in disintegrating oda axonemes.
Identification of 17–18 kDa zona pellucida binding proteins from boar spermatozoa
Authors: Moos J. , Pěknicová J. , Sumeva-Nakova Ts.N. , Pavlík M.
Published: July 2002

Zona pellucida (ZP) binding proteins from boar spermatozoa were compared with antigens recognized by ACR.2 and ACR.3 monoclonal antibodies. The ZP binding proteins of 55, 53,45 and 38 kDa are identical with various forms of boar acrosin immunologically detected by ACR.2 antibody. The ZP binding proteins of 17 and 18 kDa are recognized by ACR.3 antibody. The N‐tenninal amino acid sequence of the 17 kDa protein revealed that it is not derived from an acrosin molecule.
Amino acid sequence elucidation of human acrosin‐trypsin inhibitor (HUSI‐II) reveals that Kazal‐type proteinase inhibitors are structurally related to β‐subunits of glycoprotein hormones
Authors: Fink Edwin , Hehlein-Fink Christa , Eulitz Manfred
Published: July 2002

The amino acid sequence of the acrosin‐trypsin inhibitor HUSI‐II from human seminal plasma is presented which unequivocally identifies HUSI‐II as being of Kazal‐type. In addition, the HUSI‐II sequence shows a striking similarity to the middle part of glycoprotein hormone β‐subunits thus revealing a hitherto unknown structural and evolutionary relationship between Kazal‐type inhibitors and glycoprotein hormones.
Tris reversibly inhibits secretion of albumin and α‐1‐antitrypsin at different sites
Authors: Quinn Paul , Judah Jacob D.
Published: July 2002

We have investigated the effect of the weak base Tris on the processing and secretion of albumin and α‐1 antitrypsin by hepatocytes in culture. We show that the secretion of both proteins is 90% inhibited by 30 mM Tris. The post‐synthetic processing of both proteins is inhibited to the same extent. These effects are completely reversible. Cell fractionation indicates that albumin accumulates in the Golgi, whereas α‐1 antitrypsin fails to leave the endoplasmic reticulum.
Coenzyme B12‐dependent 2‐methyleneglutarate mutase from Clostridium barkeri Protection by the substrate from inactivation by light
Authors: Michel C. , Buckel W.
Published: July 2002

Partially purified 2‐methyleneglutarate mutase from Clostridium barkeri was separated from 3‐methylitaconate Δ‐isomerase by treatment with 3‐[(3‐cholamidopropyl)dimethylammonio]‐1‐propanesulfonate (CHAPS) followed by FPLC on the anion exchange column Mono Q in the presence of the detergent. When purified in the dark, the active mutase contained a corrinoid, most probably coenzyme B12. The enzyme was inactivated by light at the same wavelength (λ < 620 nm) and rate as free coenzyme B12. The rate was not influenced by oxygen or by temperature (O=37°C). Reactivation of up to 50% of the original activity was achieved by incubation with coenzyme B12 and diathiothreitol. The substrates 2‐methyleneglutarate (up to 40mM) or (R)‐3‐methylitaconate specifically protected the enzyme from inactivation by visible light. This effect as enhanced 3‐fold by raising the temperature from 0°C to 37°C. The data indicate that during catalysis, the Co–C bond of the coenzyme is cleaved and cannot be affected any more by light.
Characterization of neutrophil b‐type cytochrome in situ by electron paramagnetic resonance spectroscopy
Authors: Ueno Ikuko , Fujii Satoshi , Ohya-Nishiguchi Hiroaki , Iizuka Tetsutaro , Kanegasaki Shiro
Published: July 2002

Electron paramagnetic resonance spectroscopy at 4.2 K was successfully used to characterize neutrophil b‐type cytochrome in situ. The spectra or resting neutrophils taken under aerobic conditions gave a set of characteristic signals in a high magnetic field (g=2.85, 2.21 and 1.67) beside signals for myeloperoxidase and others. From the g values, shapes and the results of other experiments, these signals were attributed to those of cytochrome b
558. The results indicate that cytochrome b
558 in resting neutrophils is a hexa‐coordinated ferric hemoprotein in a low‐spin state. The obtained g??? and g??? values for the hemichrome were consistent with that of bis(imiduzole)‐coordinated hemoprotein.
Evolutionary origin of thyroglobulin by duplication of esterase gene
Authors: Takagi Yasumitsu , Omura Tsuneo , Gö Mitiko
Published: July 2002

Rat liver microsomal carboxyesterase E1 was found to have homology with five esterases and with the COOH‐terminal parts of two thyroglobulins. A phylogenetic tree constructed for these proteins shows that this new superfamily has evolved from a common ancestral gene that encoded a carboxyesterase. The tree also shows that the ancestral gene already existed before the divergence of vertebrates and invertebrates and later its duplicated genes gained various kinds of esterase activity. According to the tree, one of the duplicated genes evolved into the COOH‐terminal half of thyroglobulin by a gene fusion with a DNA sequence whose evolutionary origin is unknown.
Peptidyl‐prolyl cis‐trans isomerase activity as studied by dynamic proton NMR spectroscopy
Authors: Hübner Dorothee , Drakenberg Torbjörn , Forsén Sture , Fischer Gunter
Published: July 2002

Recently the identity of the peptidyl‐prolyl cis‐trans isomerase (PPIase), which accelerates the cis/trans isomerization of prolyl peptide bonds and cyclophilin, the binding protein for the immunosuppressive drug Cyclosporin A (CsA), was discovered. The PPIase catalysis toward the substrate Suc‐Ala‐Phe‐Pro‐Phe‐pNA has been studied by 1H NMR spectroscopy. Using the bandshape analysis technique the rate of interconversion between the cis and trans isomers of the substrate could be measured in the presence of PPIase and under equilibrium conditions. The acceleration is inhibited by equimolar amounts of CsA. The results provide evidence that the PPIase catalysis is more complex than a simple exchange between two states.
Functional expression of a human C5a receptor clone in Xenopus oocytes requires additional RNA
Authors: Kroll Beate , Emde Monica , Jeromin Andreas , Penner Lothar , Rechkemmer Gerhard , Kretzschmar Titus , Klos Andreas , Köhl Jörg , Bautsch Wilfried
Published: July 2002

cRNA from a PCR‐generated C5aR clone was prepared by in vitro transcription and microinjected into Xenopus laevis oocytes. Ligand‐induced whole cell current could be detected after co‐injection of cRNA for the C5aR with total RNA of the unstimulated U937 cell line, but not with either of the components injected alone. These data clearly demonstrate an absolute requirement of the C5aR for an additional human factor to become functionally expressed in Xenopus oocytes.
Structure and RNA content of the prosomes
Authors: Coux Olivier , Nothwang Hans G. , Scherrer Klaus , Bergsma-Schutter Wilma , Arnberg Annika C. , Timmins Peter A. , Langowski Jörg , Cohen-Addad Claudine
Published: July 2002

Duck erythroblast, prosomes were analysed by small angle neutron scattering (SANS), dynamic light scattering and (cryo‐)electron microscopy. A molecular weight of ≈ 720,000 ± 50,000, a radius of gyration of 64 ± 2 Å and a hydrodynamic radius of ≈ 86 Å were obtained. Electron micrographs show a hollow cylinder‐like particle with a diameter of 120 Å, n height of 170 Å and a diameter of 40 Å for the cavity, built of four discs, the two outer ones being more pronounced than those in the center. Results from SANS indicate less then 5% of RNA in the purified prosomes, but nuclease protection assays confirm its presence.
Imidazole‐SDS‐Zn reverse staining of proteins in gels containing or not SDS and microsequence of individual unmodified electroblotted proteins
Authors: Ortiz Maria Luisa , Calero Miguel , Patron Carlos Fernandez , Castellanos Lila , Mendez Enrique
Published: July 2002

A reverse staining procedure is described for the detection of proteins in acrylamide and agarose gels with and without SDS. Protein detection occurs a few minutes after electrophoresis. The sensitivity on acrylamide gels is higher than that of Coomassie blue staining either on acrylamide gels or on electrotransferred membranes. Sequencing of protein bands only detected by reverse staining on the gel and not by Coomassie blue is demonstrated.
The receptor for the plasminogen activator of urokinase type is up‐regulated in transformed rat thyroid cells
Authors: Ragno Pia , Cassano Silvana , Degen Jay , Kessler Cherie , Blasi Francesco , Rossi Guido
Published: July 2002

Five rat thyroid cell lines were tested for the expression of the cell surface receptor for urokinase type plasminogen activator (uPA). All tested lines were found to bind uPA, but transformed 1–5G and Ki‐Mol cells, which are also high uPA producers, bound at least ten times more uPA, as compared to non‐producers, ‘normal’ TL5 cells. Moreover, it was possible to remove membrane‐bound uPA by treating the cells with phosphatidylinositol‐specific phopholipase C, suggesting that rat uPAR, like its human counterpart, is linked to the membrane by a glucosyl‐phosphatidylinositol anchor. The specificity of the binding was tested by competition with three different synthetic peptides corresponding to amino acids 14–37 of human, rat and mouse uPA. The results indicate also that the receptor binding region of rat uPA is located within the growth factor domain of the molecule and that its expression may be dependent on the transformed state of the cells.
Isolation, sequencing and expression in E. coli of the urocanase gene from white clover (Trifolium repens)
Authors: Koberstaedt Andreas , Lenz Martin , Retey János
Published: July 2002

The urocanase gene was detected in a clone obtained from a genomic library of white clover. The entire gene has been sequenced and expressed in the pT7‐7/E. coli BL 21 (DE 3) system. The deduced sequence of the plant urocanase is 72% homologous with that of the well‐characterized urocanase from Pseudomonas putida. The purification procedure, as well as kinetic and electrophoretic behaviour, of the new enzyme are described.
Glucose decreases respiratory control ratio in EL‐4 tumor cells
Authors: Gabai Vladimir L.
Published: July 2002

EL‐4 ascites thymoma cells are shown to have high aerobic glycolysis and decreased Pasteur effect. At the same time, glucose produces a much smaller inhibitory effect on cell respiration (Crabtree effect) than in Ehrlich ascites carcinoma (EAC) cells. In intact EL‐4 cells, the respiratory control ratio (RCR) was found to be 6.2 with endogenous substrates and 8.0 with glutamine. Glucose decreased the RCR to 3.2, by stimulating, the state 4 respiration. In rat thymocytes and EAC cells, such an effect of glucose was absent (RCR of 7.0 and 7.2, respectively). It is suggested that in EL‐4 tumor cells, the high aerobic glycolysis and small Crabtree effect may be due to glucose‐induced ‘uncoupling’ of oxidation and phosphorylation.
Recombinant GABAA receptor function and ethanol
Authors: Sigel Erwin , Baur Roland , Malherbe Pari
Published: July 2002

Different combinations of cloned subunits of the rat brain GABAA receptor were expressed in Xenopus oocytes. Possible effects of ethanol on the expressed GABA‐induced chloride current were determined. The consequence of replacing the γ2s subunit by the alternatively spliced variant γ2L was specifically tested on the responsiveness to ethanol. A significant stimulation of the GABA response was only observed at very high concentrations (> 60 mM) of ethanol. No differential response was observed between subunit combinations containing different γ2 subunit splice variants.