bluuebunny/crossref_metadata_2025 huggingface dataset:
I Am More Committed to My Profession Than to My Organization
Authors: Buhari Mufitha Mohamed , Yong Chen Chen , Lee Su Teng
Published: April 2020

Given its knowledge centred nature, retaining key talents is essential for any IT organization. Inability to do so reflects a failure in employee-organization relationship. Since IT professionals possess unique workplace behaviours, it is presumed that they leave organizations as more committed to the profession. Thus, the study aimed to investigate the influence of professional commitment and perceived organizational support on IT professionals' turnover intention. Data was analysed using a structural equation model. A sample of 96 software engineers revealed that professional commitment negatively influences turnover intention while its effect is partially mediated by job satisfaction. Surprisingly, unlike for other employees, for IT professionals, perceived organizational support had no influence on turnover intention: instead stimulated job satisfaction. Similarly, professional commitment stimulates job satisfaction. Job satisfaction negatively influenced the turnover intention. Gender showed no moderating effect on the relationship between job satisfaction and turnover intention while career stage moderated the relationship. The comparison between the findings of professional commitment and perceived organizational support directs IT firms to re-visit presumptions about IT professionals and to re-assess what is meant by organizational support to IT professionals. Since gender had no effect on the job satisfaction-turnover intention relationship, both male and female IT professionals must be acknowledged for their equal professionalism in the industry. IT companies must take initiatives to retain talented early career staged IT professional who have proven to easily leave their organizations compared to others. Such efforts can be integrated to professional commitment and job satisfaction.
CURRENT PERSPECTIVES ON THE MICROBIOTA-GUT-BRAIN AXIS IN CHRONIC NEURODEGENERATIVE DISORDERS
Authors: Albani Diego , Giordano Carmen
Published: April 2020

Chronic neurodegenerative disorders are mostly due to population aging. These invalidating conditions include dementia (as Alzheimerâ€™s disease - AD) and movement disorders (as Parkinsonâ€™s disease - PD). In the past decades, we have been accumulating experimental evidence on the molecular triggers of AD/PD and few approved drugs are available, unfortunately with no real disease-modifying action. As AD/PD cases constantly rise in the world, new hypothesis on their pathogenesis are actively under investigation. One of this is based on the microbiota-gut-brain axis, that postulates a direct or indirect influence of the microbial host community of human gut on the nervous system and its functions. This bidirectional interaction may play a role also in neurodegenerative disorders, even though research in this field requires models and tools for growing to a clinical translational perspective. To this respect, innovative in vitro engineered disease models are gaining attention, particularly because they feature desirable characteristics as tridimensional (3D) growing conditions and interstitial fluids movement recapitulation thanks to microfluidics. Here we summarize current data on the impact of gut microbiota on AD/PD models and patients, with a focus on ongoing research projects on the topic that are trying to unravel clinical questions or elaborate technical solutions for research and industry applications in the field.
Esportes de aventura praticados na Barra da Tijuca e São Conrado, RJ: um levantamento das modalidades e formação do instrutor
Authors: Triani Felipe Da Silva , Sampaio Bruno Henrique Ribeiro , Castro Leonardo Mota de , Paixão Jairo Antônio Da
Published: April 2020

Buscou-se identificar e analisar quais são os esportes de aventuras mais praticados na Barra da Tijuca e São Conrado, bem como a formação dos instrutores responsáveis pela condução dessa vertente esportiva nos referidos espaços naturais do Rio de Janeiro. A partir de um estudo de campo, com um grupo amostral de 176 instrutores foi possível afirmar que os esportes de aventura mais praticados são voo livre (81%), kitesurf (7%), surf (5%), trilha (5%), rapel (2%) e escalada (1%). Quanto à formação profissional, a investigação permite sinalizar que apenas 14% do total de instrutores possuíam formação em Educação Física. Portanto, o estudou concluiu que os esportes de aventura mais praticados nas regiões são os de mar e montanha, além de desvelar a necessidade de formação em Educação Física, bem como cursos de capacitação de instrutores de esportes de aventura, bem como para formação daqueles que têm interesse por atuação nesse campo.
Cultura corporal de movimento em pauta: uma análise sobre o objeto de ensino da Educação Física como vetor dos processos de subjetivação com o corpo
Authors: Ghidetti Filipe Ferreira , Rodrigues Renata Marques
Published: April 2020

Trata de um aspecto importante para a prática pedagógica da EF: a relação possível entre o ofício de professor e o objeto de ensino, após as reformulações nas propostas progressistas. A ideia de “cultura corporal de movimento” não resolve a contradição de tomar as práticas corporais como substrato da conscientização sobre a condição humana ou engendrar as práticas corporais como forma de resistir à dominação. Busca o conceito de práticas corporais para tensionar a ideia de que há um intercâmbio direto de sentido entre corpo e cultura. Para isso, analisamos como praticantes de Futebol Freestyle se organizavam quando a prática se destacava como algo diferente do futebol através da análise de um fórum, evidenciando processos de subjetivação; e analisamos obras que tratam especificamente do tema. Entendemos que as práticas corporais apresentam imanência material, o que pode ser um caminho para as práticas pedagógicas da EF.
Prioritizing Medication Management Criteria of National Hospital Accreditation Standards Using FDANP Model
Authors: Izadpanah Fatemeh , Shiehmorteza Maryam , Rahimpour Amirissa , Moradi Mandana
Published: April 2020

Introduction: Accreditation is an evaluating tool of health care systems especially in hospitals: Iran’s Ministry of Health emphasizes its importance. We attempted this descriptive study to classify medication management criteria of hospital accreditation standards using a hybrid approach of fuzzy DEMATEL based on ANP (FDANP).

Methods: This study included all Iran’s hospitals. Nine medication management criteria and their sub-criteria were evaluated. AHP questionnaire was used for data collection.

Results: The following were demonstrated to be effective: The standards of safe storage of drugs and medical equipment, and providing practical procedure for reporting and controlling medication errors. The other factors were affected by them: Continuous monitoring of drugs and medical equipment utilization was the most affected and not independent factors/standards.

Conclusion: Focus should be made on effective standards and their related measures, not on standards affected by other factors/standards.
Release of leukotriene C4 from human polymorphonuclear leucocytes as determined by radioimmunoassay
Authors: Aehringhaus U. , Wölbling R.H. , König W. , Patrono C. , Peskar B.M. , Peskar B.A.
Published: July 2002

Rabbits were immunized with a conjugate of leukotriene (LT) C4 and bovine serum albumin prepared by coupling the single free amino group of the hapten to the protein using gluteraldehyde. Binding of [3H]LTC4 to the antibodies obtained is inhibited by 50% with 1.5 ng LTC4. The relative cross‐reaction of LTD4 is 16% and of LTC4‐methyl ester 3.6%. The validity of the radioimmunoassay was demonstrated by comparison with bioassay using the isolated guinea pig ileum. Using the radioimmunoassay it could be shown that endogenous LTC4 is released in a dose‐dependent manner by human polymorphonuclear leucocytes stimulated with the divalent cation ionophore A23187.
Identification of multiple components in the intermediary electron carrier complex of photosystem I
Authors: Bonnerjea J. , Evans M.C.W.
Published: July 2002

Illumination at 230 K of dithionite‐reduced particles results in the appearance of an EPR detectable radical 13 G wide with g = 2.0033. This radical is formed in a ratio of 2.28 (±0.5)/P700. Investigation of the time course of formation shows two components are present. One (A
1) has g = 2.0051 and the other (A
o
g= 2.0024. Reduction of A
1 results in an increase in reaction centre triplet formation, subsequent reduction of A
o results in a decrease of triplet formation to the base level. We propose that these components function sequentially in the transfer of electrons from P700 to the iron—sulphur acceptors.
Mechanisms for the emergence of catecholamine‐sensitive adenylate cyclase and β‐adrenergic receptors in cultured hepatocytes
Authors: Refsnes M. , Sandnes D. , Melien Ø. , Sand T.E. , Jacobsen S. , Christoffersen T.
Published: July 2002

Adult male rat hepatocytes, which normally respond poorly to β‐adrenergic agents, acquire such responsiveness during primary monolayer culture. We here show that the rise in catecholamine‐sensitive adenylate cyclase activity in hepatocytes in vitro is closely paralleled by an increase in the ability to bind the β‐adrenoceptor ligand [125I]cyanopindolol. The emergence of β‐adrenergic responsiveness did not require cell attachment or serum. Addition of dexamethasone, insulin, thyroxine or dihydortestosterone to the cultures, singly or in combination, did not prevent the augmented β‐adrenergic responsiveness. The increase in catecholamine‐sensitive adenylate cyclase activity and [125I]cyanopindolol binding could be blocked by cycloheximide or actinomycin D. Exposure of the cultures to isoproterenol at 3‐hourly intervals led to a dose‐dependent suppression of the rise in isoproterenol‐responsive adenylate cyclase and prevented the increase in β‐adrenoceptor binding.
Cytochrome b6 from isolated cytochrome b6f complexes
Authors: Hurt Eduard C. , Hauska Günter
Published: July 2002

Cytochrome b
6 from spinach chloroplasts (either within the purified cytochrome b
6
f complex, or in its isolated form) exhibits two spectral species, which correspond to two midpoint potentials. This can be demonstrated by low temperature difference spectroscopy at fixed redox potentials. The high potential form of cytochrome b
6 has a split α‐peak at 557.5 and 561.5 nm, the low potential form has a symmetrical α‐peak at 560.5 nm. Similar results were obtained with cytochrome b
6 in the isolated cytochrome b
6
f complex from the cyanobacterium Anabaena variabilis.
Decrease in apparent Km for oxygen after stimulation of respiration of rat polymorphonuclear leukocytes
Authors: Edwards Steven W. , Hallett Maurice B. , Lloyd David , Campbell Anthony K.
Published: July 2002

The respiratory burst of polymorphonuclear leukocytes, induced by the addition of chemotactic peptide (N‐formyl‐methionyl—leucyl—phenylalamine) and cytochalasin B was found to consist of two phases. The first phase of very rapid oxygen uptake lasted 1–3 min. and was followed by a second more prolonged phase of lower magnitude. The apparent K
m for oxygen of unstimulated cells was 9.6 ± 0.67 μM, while that of the second phase of stimulation was 3.7 ± 1.6 μM oxygen. The possibility that lowered oxygen concentrations may regulate polymorphonuclear leukocyte activity in some pathological conditions is discussed.
Phosphorylation of chloroplast thylakoid membrane proteins does not increase the absorption cross‐section of photosystem 1
Authors: Haworth Philip , Melis Anastasios
Published: July 2002

Direct measurements on the effective absorption cross‐section of photosystem (PS) 1 were obtained with control (light — ATP) and phosphorylated (light + ATP) chloroplast thylakoids from spinach. The rate of light absorption by PS1 was invariant in control and phosphorylated thylakoids, suggesting a constant functional antenna size for this photosystem. We conclude that phosphorylated chlorophylla‐blight‐harvesting complex from PS2 is not functionally connected with the antenna pigment of PS1.
Polarized absorption picosecond kinetics as a probe of energy transfer in phycobilisomes ofSynechococcus6301
Authors: Gillbro Tomas , Sandström Åke , Sundström Villy , Holzwarth Alfred R.
Published: July 2002

The energy transfer between C‐phycocyanin chromophores in intact phycobilisomes ofSynechococcus6301 is shown to lead to an anisotropy relaxation with a lifetime of 10 ± 2 ps. However, due to the molecular order within the hexameric units of C‐phycocyanin the anisotropy does not decay to zero. The Förster dipole‐dipole mechanism of energy transfer can qualitatively explain these data provided that there is no back transfer of excitation energy and that the chromophore distribution is non‐random. The rate of energy transfer in phycobilisomes between C‐phycocyanin and allophycocyanin can best be described by a double exponential with lifetimes of 12 ± 3 and 84 ± 8 ps.
1H NMR of intact muscle at 11 T
Authors: Arús Carlos , Bárány Michael , Westler William M. , Markley John L.
Published: July 2002

1H NMR spectra of intact frog, and chicken skeletal muscles, were recorded at 470 MHz with the Plateau and Guéron pulse sequence for the suppression of water [(1982) J. Am. Chem. Soc. 104, 7310]. Only a few transients were required to resolve the resonances from the protons of muscle metabolites. The previously unobserved exchangeable protons of muscles were also recorded and thereby phosphocreatine and creatine could be measured simultaneously. During aging of dissected frog muscle, changes in levels of phosphocreatine, creatine and lactic acid, and the decrease in the intracellular pH were followed by 1H NMR.
UV‐spectral characterization in Tris‐washed chloroplasts of the redox component D1which functionally connects the reaction center with the water‐oxidizing enzyme system Y in photosynthesis
Authors: Weiss W. , Renger G.
Published: July 2002

Amplitude and relaxation kinetics of UV‐absorption changes induced in Tris‐washed chloroplasts by the second flash of repetitive double flash groups were found to be dependent on the time between the flashes of each group. An analysis of these data leads to the conclusion that after oxidation by P680+the donor component, Dox1, becomes mainly reduced by the primary (Q−A) and secondary (Q−B) plastoquinone in non‐B‐type and B‐type system II centers, respectively. Dox1reduction with Q−Aoccurs witht1/= 60–100 ms, and Dox1reduction with Q−Bis biphasic with half‐times of 0.1–0.5 and 5–10 s. The difference spectrum of the oxidizedvsreduced form of D1is presented in the range 250–370 nm. It is characterized by positive bands peaking at 265–270 and 300–305 nm with a smaller band around 350 nm; negative bands are not observed.
Prediction structure type for human leukocyte Interferon subtype A from circular dichroism
Authors: Manavalan P. , Johnson W.Curtis , Johnston Paul D.
Published: July 2002

Vacuum UV circular dichroism studies were carried out on human leukocyte interferon subtype A. The secondary structure analysis for the CD spectrum shows 59% α‐helix, 16% antiparallel β‐sheet, no parallel β‐sheet, 18% β‐turns and 13% other structures. The analysis of the CD features for the prediction of tertiary structural class reveals that it is an all‐α type protein.
High resolution proton NMR studies of perfused rat hearts
Authors: Ugurbil Kamil , Petein Marc , Maidan Rubin , Michurski Steve , Cohn Jay N. , From Arthur H.
Published: July 2002

High resolution 1H NMR spectra of perfused rat hearts have been obtained under normoxic, ischemic and hypoxic conditions. Several myocardial metabolites including taurine, carnitine, lactate and tissue glycerides are detected in the 1H NMR spectra. Changes in oxygen availability induce perturbations in the levels of some metabolites, in particular, lactate. Experiments with fasted rats and with substrate‐free perfusion suggest that the glycerides detected in 1H spectra are metabolically mobilizable but have a slow rate of turnover. These results demonstrate that utility of 1H NMR in monitoring myocardial metabolism.
Pyrimidine metabolism in Trichomonas vaginalis
Authors: Heyworth Paul G. , Gutteridge Winston E. , Ginger Colin D.
Published: July 2002

Pyrimidine metabolism in Trichomonas vaginalis was investigated using washed cell suspensions of the organism with radiolabelled pyrimidine ring precursors and preformed pyrimidines. The precursors [14C]orotate, [14C]bicarbonate and [14C]aspartate were not incorporated into the pyrimidine bases of trichomonal nucleic acids, indicating that the protozoan is unable to synthesise the pyrimidine ring and is dependent on the salvage of exogenous pyrimidines. [3H]uracil, [3H]uridine, [3H]cytidine, deoxy[3H]cytidine and [3H]thymidine were all efficiently salvaged, and interconversion between cytosine and uracil nucleotides was detected. Thymidylate synthase activity was not detected, suggesting that T. vaginalis is dependent upon an exogenous supply of thymidine for TMP synthesis.
Echinocandin inhibition of 1,3‐β‐D‐glucan synthase from Candida albicans
Authors: Sawistowska-Schröder E.T. , Kerridge D. , Perry H.
Published: July 2002

The cyclic peptide antibiotic echinocandin was found to inhibit 1,3‐β‐D‐glucan synthase activity present in a mixed membrane fraction from Candida albicans. Addition of antibiotic reduced the V
max of the enzyme, but the K
m was unaffected. GTP stimulated enzyme activity ~ 4‐fold, but did not affect the percentage inhibition of the enzyme by echinocandin. Treatment of the reaction products with α‐amylase and β‐glucanase confirmed that the polymer synthesised was 1,3‐β‐D‐glucan, not glycogen.
Formation of metal complexes of tumor‐localizing porphyrins
Authors: Sommer S. , Rimington C. , Moan J.
Published: July 2002

Whereas the tumor localizer and photosensitizer hematoporphyrin derivative (Hpd) has its fluorescence emission maximum at 610–630 nm, several authors have reported that in aqueous solutions of hematoporphyrin (Hp) and Hpd, or in tumors after an injection of Hpd, a compound is formed which has its fluorescence emission maximum at 570–590 nm. This work (HPLC and fluorescence analysis) indicates that this peak is due to the formation of Zn‐porphyrins either in vitro or in vivo. Cu‐ and, Co‐porphyrins may be formed as well, from traces of these metallic ions. In contrast to free porphyrins and Zn‐porphyrins the latter complexes are non‐fluorescent and do not act as photosensitizers.
The question of the intermediate state P+Chl‐in bacterial photosynthesis
Authors: Kirmaier Christine , Holten Dewey , Parson William W.
Published: July 2002

In bacterial photosynthesis it has been proposed that an electron is transferred from the excited singlet state (P∗) of theprimary electron donor first to a bacteriochlorophyll (BChl) molecule, generating a P+Chl charge‐transfer state, and that BChl‐subsequently (4–7 ps) transfers an electron to a bacteriopheophytin molecule. Here we review the evidence for and against the intermediacy of P+BChl‐and present picosecond transient absorption and kinetic data that bear on this point. We conclude that there is no convincing evidence that P+BChl is a kinetically or spectrally resolved intermediary state in the charge separation process.
Affinity of protein HU for different nucleic acids
Authors: Holck Askild , Kleppe Kjell
Published: July 2002

The binding of protein HU from Escherichia coli to nucleic acids was investigated by affinity chromatography under various conditions, by a nitrocellulose retention assay and by isopycnic centrifugations in metrizamide gradients. The results indicate that HU has a preference for binding to RNA and single‐stranded DNA over double‐stranded DNA. The affinity of HU for supercoiled DNA was also less than that of the corresponding relaxed DNA.
Purification of liver and hepatoma membrane proteins by high‐performance liquid chromatography
Authors: Josić Dj. , Schuett W. , Neumeier R. , Reutter W.
Published: July 2002

This paper documents the recovery of selected proteins from hepatic plasma membranes. Initial purification, achieved by a series of stepwise extractions, facilitates the subsequent purification by HPLC. Examples are provided to illustrate the recovery of specific proteins from two Morris hepatoma lines and the liver.
Distribution of intrinsic and extrinsic subunits of the PS II protein complex between appressed and non‐appressed regions of the thylakoid membrane: an immunocytochemical study
Authors: Vallon O. , Wollman F.A. , Olive J.
Published: July 2002

The distribution of photosystem (PS) II centers between appressed and non‐appressed domains of the thylakoid membranes has been investigated, using immunogold labeling, inC. reinhardtiiand in spinach. We have used antibodies directed against the two main intrinsic subunits of the PS II center and against two extrinsic subunits of the O2‐evolving site. 90% of the two intrinsic PS II antigens are located in the appressed membranes, in a density 3–3.5‐fold higher than in the non‐appressed regions. The same distribution is observed for the two extrinsic antigens. This result suggests that the O2‐evolving system is associated with the PS II center, both in appressed and in non‐appressed regions of the thylakoid membrane.
Isolation and characterisation of a photosystem II reaction centre lipoprotein complex
Authors: Gounaris Kleoniki , Barber James
Published: July 2002

A photochemically active reaction centre complex has been isolated from photosystem II preparations of spinach chloroplasts by Triton X‐100 solubilisation and sucrose gradient fractionation. Electrophoresis of the complex revealed 5 bands indicating polypeptides of apparent molecular masses of 47, 43, 33, 30 and 10 kDa. Lipid analyses showed that polar, as well as neutral, lipids are associated with the complex. For approx. 40 chlorophyllamolecules there were 3.4 plastoquinone‐9, 3.3 pheophytina, 2.9 β‐carotene, 29.3 monogalactosyldiacylglycerol and 12.4 sulphoquinovosyldiacylglycerol molecules. These results suggest that this photosystem II reaction centre complex, which most likely represents a minimum photochemically active unit, is a lipoprotein complex. A striking feature of the associated polar lipids is their very low degree of unsaturation.
Simple and discrete isolation of an O2‐evolving PS II reaction center complex retaining Mn and the extrinsic 33 kDa protein
Authors: Ikeuchi Masahiko , Yuasa Mitsuyoshi , Inoue Yorinao
Published: July 2002

Oxygen evolutionPS IIReaction center33 kDa proteinOctylglucopyranosidePhotosynthesis
Proteolysis of mitochondria in reticulocytes during maturation is ubiquitin‐dependent and is accompanied by a high rate of ATP hydrolysis
Authors: Rapoport S. , Dubiel W. , Müller M.
Published: July 2002

The ATP‐dependent breakdown of mitochondria‐containing stroma proceeds via the ubiquitin‐requiring pathway. The proteolysis is linked to a large ATP‐cleaved consumption amounting to 1 ATP per peptide bond or more. Proteins of mitochondria‐containing stroma are much better substrates of ATP‐ubiquitindependent proteolysis than heat‐denatured ones. Hemin suppresses both proteolysis and ATP hydrolysis.
Rapid electron transfer reactions associated with oxygen evolution in photosystem II preparations from spinach andPhormidium laminosum
Authors: Brettel K. , Ford R.C. , Schlodder E. , Atkinson Y.E. , Witt H.T. , Evans M.C.W.
Published: July 2002

We have measured the nanosecond kinetics of Chl‐a+IIreduction in oxygen‐evolving detergent preparations of PS II from the cyanobacteriumPhormidium laminosumand from higher plants (spinach) at 824 and 680 nm. Compared to earlier studies at 680 nm with higher plant material, we obtained an improved signal: noise ratio for measurements on a ns to ms time scale. The kinetics of Chl‐a+IIreduction in the ns range are consistent in the two preparations and are comparable to other studies of higher plant and cyanobacterial material. The ns kinetics are tightly connected to the ability for O2evolution. Analysis of the μs kinetics indicates three phases: (a) the slow phase (t½~ 150 μs in spinach and ~ 500 μs inPhormidium) reflects the back reaction between Chl‐a+IIand Q−; (b) the phase witht½5–10 μs is probably due to a donor which is not connected to an intact water oxidation system; (c) the intermediate μs component (t½30–40 μs) may be related to water oxidation.
Light‐induced conformational change in rhodopsin detected by modification of G‐protein binding, GTPγS binding and cGMP phosphodiesterase activation
Authors: Pellicone C. , Cook N.J. , Nullans G. , Virmaux N.
Published: July 2002

CNBr treatment of rod outer segments was performed in dark and in light conditions. With the subsequent modified rhodopsin and opsin the cGMP phosphodiesterase activation system was reconstituted. The recombination systems exhibited greatly reduced G‐protein binding, GTPγS binding and cGMP phosphodiesterase activation. The reduction in activity of these three steps of the PDE activation cascade is most significant with modified opsin and is shown to be due to its inability to bind the Gα subunit. The correlation between the localization of CNBr cleavage in dark and light conditions and these results is strongly indicative that a light‐induced conformational change occurs in two extradiscal regions of rhodopsin.
Protein kinase C phosphorylates a component of NADPH oxidase of neutrophils
Authors: Papini Emanuele , Grzeskowiak Miroslawa , Bellavite Paolo , Rossi Filippo
Published: July 2002

NADPH oxidase
Cytochrome b−245

Phosphorylation
Protein kinase
Neutrophil activation
Respiratory burst
Changes in the composition of membrane phospholipids during the cell cycle of Escherichia coli
Authors: Mozharov A.D. , Shchipakin V.N. , Fishov I.L. , Evtodienko Yu.V.
Published: July 2002

Phospholipid concentrations have been estimated throughout the successive cell cycle in synchronously growing culture of E. coli B/r. Total phospholipid phosphorus was shown to be doubled in the period of time between two cell divisions, whereas during the division itself it did not change. Phosphatidylethanol‐amine (PE) and phosphatidylglycerol (PG) exhibit a stepwise increase during the cell cycle. It should be noted that the phase of accumulation of these lipids could shift depending on the duration of the cell cycle. The fall in level of PE was followed by a short‐term increase (5–10 min). At the same time the level of cardiolipin was observed to be significantly increased.
The photochemical cycle of bacteriorhodopsin has no refractory period
Authors: Dancshazy Z. , Groma G.I. , Oesterhelt D. , Tittor J.
Published: July 2002

Double‐pulse experiments were used to probe the existence of a refractory period in the photochemical cycle of bacteriorhodopsin. We demonstrate using three different approaches that no refractory period exists in purple membranes, cell vesicles or intact cells. First, we showed by applying different time delays between two flashes that every molecule which regained the initial optical state could immediately recycle again. Second, we found no difference in the effectiveness of the first and second flash when the intensity was varied. Third, different steady‐state levels of the intermediates were produced with different intensities of continuous background illumination. No difference in effectivity of the first and second flash could be detected.
Lysis of chromaffin granules by phospholipase A2‐treated plasma membranes
Authors: Izumi Futoshi , Yanagihara Nobuyuki , Wada Akihiko , Toyohira Yumiko , Kobayashi Hideyuki
Published: July 2002

The possible involvement of phospholipase A2 (PLA2) in the release of catecholamines was examined in a cell‐free model system, using isolated chromaffin granules and plasma membranes of adrenal medulla cells. Plasma membranes treated with PLA2 in the presence of Ca2+ caused lysis of chromaffin granules which was also dependent on Ca2+. This finding suggests that Ca2+ acts in two steps of exocytosis, namely in the transformation of plasma membranes into a lytic form by PLA2+ and in the interaction of chromaffin granules with plasma membranes. These findings show good agreement with recently reported findings in leaky adrenal medulla cells, and suggest the involvement of PLA2+ in the release of catecholamines.
Amino acid sequence of human plasma apolipoprotein C‐III from normalipidemic subjects
Authors: Hospattankar Ashok V. , Bryan Brewer H. , Ronan Rosemary , Fairwell Thomas
Published: July 2002

The complete amino acid sequence of human plasma apolipoprotein C‐III (apoC‐III) isolated from normal subjects is described. ApoC‐III is a linear polypeptide chain of 79 amino acids. Tryptic digestion of intact apoC‐III produced 5 major peptides, while tryptic digestion of the citraconylated protein yielded two peptides. The complete amino acid sequence of apoC‐III was determined by the automated Edman degradation of the intact protein as well as the various tryptic peptides. Phenylthiohydantoin amino acids were identified by high‐performance liquid chromatography and chemical ionization mass spectrometry. The amino acid sequence of apoC‐III isolated from normalipidemic subjects is identical to the apoC‐III sequence derived from the cDNA sequence and differs at 4 positions from the previously reported sequence of apoC‐III derived from a patient with type V hyperlipoproteinemia.
A general model for regulation of photosynthetic unit function by protein phosphorylation
Authors: Allen John F. , Holmes Nigel G.
Published: July 2002

We propose that regulatory effects of membrane protein phosphorylation in photosynthetic systems result in all cases from simultaneous phosphorylation by a single kinase of the polypeptides of two intrinsic pigment‐protein complexes, with phosphorylation leading to their mutual electrostatic repulsion in a direction parallel to the membrane plane and therefore to decreased excitation energy transfer between them. One complex is a peripheral light‐harvesting complex and the other is bound to the reaction centre and functions as a link in excitation energy transfer. Immediate effects of phosphorylation are therefore decreased absorption cross‐section together with decreased cooperativity of photosynthetic units. This general model applies equally to photosystem II of green plants, algae and cyanobacteria, as well as to the single photosystem of purple bacteria. Special cases of this general model permit increased excitation energy transfer to one type of reaction centre at the expense of another, and this may occur even in laterally homogeneous membranes that are uniformly unappressed.
UV optical difference spectrum associated with the reduction of electron acceptor A1in photosystem I of higher plants
Authors: Mansfield R.W. , Evans M.C.W.
Published: July 2002

Photosystem I particles containing I P700 per 32 chlorophyll molecules were illuminated at cryogenic temperatures in the presence of sodium dithionite. Under conditions which specifically led to reduction of acceptor a1(as shown by its characteristic EPR spectrum) optical absorbance changes were detected between 240 and 325 nm. The appearance of these changes correlated closely with the increase in amplitude of the ai EPR signal. The possibility that a quinone‐like species is associated with, or directly involved in intermediary PS I electron flow is discussed.
Photosystem II particles largely depleted in the two intrinsic polypeptides in the 30 kDa region from Synechococcus sp.
Authors: Satoh Kazuhiko
Published: July 2002

Treatment of oxygen‐evolving photosystem II particles isolated from the thermophilic cyanobacterium, Synechococcus sp. with β‐octylglucoside specifically solubilized two intrinsic polypeptides of 31 and 28 kDa from the particles. The removal of the two polypeptides had no significant effect on photoreduction of the bound quinone acceptor QA. The results indicate that the 31 and 28 kDa polypeptides are not essential for the primary charge separation and subsequent reduction of QA and hence support the view that the reaction center and QA are located on the chlorophyll‐carrying 47 kDa subunit.
Sub‐picosecond measurements of primary electron transfer inRhodopseudomonas viridisreaction centers using near‐infrared excitation
Authors: Wasielewski Michael R. , Tiede David M.
Published: July 2002

Rate constants for the primary photoinduced electron transfer reactions within the reaction center protein of the photosynthetic bacteriumRhodopseudomonas viridishave been measured using transient optical absorption spectroscopy following excitation of the primary donor P960 directly with 950 nm laser flashes. The time resolution of the experiments was 0.45 ps. The reduction of BPheobas indicated by absorption changes at 543 nm exhibits monophasic kinetics with a 1.7 × 1011s1̄rate constant following direct excitation of P960. Spectral changes at 805 and 835 nm due to perturbations of the intermediary BChlboccur synchronously with those at 543 nm. There is no evidence for formation of BChlb−as a distinct chemical intermediate preceding the reduction of BPheob.
Serological relationship between reverse transcriptases from human T‐cell lymphotropic viruses denned by monoclonal antibodies
Authors: Chandra A. , Gerber T. , Kaul S. , Wolf C. , Demirhan I. , Chandra P.
Published: July 2002

The immunological relationship between reverse transcriptases purified from human T‐cell lymphotropic viruses (HTLV‐I, HTLV‐II, HTLV‐III) was defined using monoclonal antibodies specific for HTLV‐III reverse transcriptase, secreted by a mouse/mouse hybridoma clone (4F8) developed in our laboratory. The viral proteins from HTLV‐I and HTLV‐II do not bear any cross‐reactive epitope to antibodies secreted by this clone. These antibodies specifically cross‐react with HTLV‐III reverse transcriptase. The antibodies failed to neutralize the catalytic activity of reverse transcriptase; however, after immunoprecipitation with a magnetic conjugate of goat anti‐mouse IgG, the residual activity was completely inhibited. This shows that the antibodies are not directed towards the catalytic active center of the enzyme. Using an immunoblotting technique (Western blotting), we have found two cross‐reactive proteins with HTLV‐III lysate with molecular masses of 53 and 66 kDa. This suggests that HTLV‐III possesses two reverse transcriptase activities with a common determinant recognized by the same epitope.
Are microtubules cold‐stable in the Atlantic cod, Gadus morhua?
Authors: Strömberg E. , Jönsson A.-C. , Wallin M.
Published: July 2002

The amount of axonally transported proteins in the nervus splanchnicus of cod (Gadus morhua) was found to be temperature‐dependent in vitro, with an optimum at 8°C. The transport was markedly reduced at 2°C, probably caused by decreased protein synthesis rather than disassembly of microtubules. Microtubules were isolated from cod brain by cycles of assembly‐disassembly. These microtubules were cold‐labile, had a low amount of microtubule‐associated proteins and a high critical concentration for assembly. The possibilities exist that a cold‐stabilizing factor or cold‐stable microtubules are lost during the preparation, or that cold‐stable microtubules are components of the peripheral axons only.
Effect of insulin on aminoisobutyric acid uptake by human non‐rheumatoid and rheumatoid synovial cells
Authors: Aussel Christian , Desmoulins Dominique , Agneray Jean , Ekindjian Ovhanesse G.
Published: July 2002

The biological sensitivity of cultured non‐rheumatoid human synovial cells (NRSCs and rheumatoid synovial cells (RSCs) was examined in terms of the ability of insulin to stimulate the uptake of α‐aminoisobutyrate (AIB). NRSCs, like numerous fibroblastic lines, were sensitive to physiological concentrations of the hormone: half‐maximal stimulation was obtained with (4 × 10−10 M) insulin, while maximum transport was found with a 60–90 min association time. On the contrary, although the basal transport was similar in RSCs, insulin was totally unable to accelerate AIB transport in these cells. Inflammatory processes lead to an insulin resistance which most likely involves a post‐receptor step at the cellular level.
Myosin light chain phosphorylation in intact human muscle
Authors: Houston M.E. , Lingley M.D. , Stuart D.S. , Grange R.W.
Published: July 2002

The phosphate content of the fast (LC2F) and two slow (LC2S and LC2S1) phosphorylatable light chains (P‐light chains) in myosin isolated from biopsy samples of rested human vastus lateralis muscle averaged 0.21, 0.28 and 0.25 mol of phosphate per mol of P‐light chain, respectively. Following a 10 s maximal contraction, phosphate content was increased by almost 2‐fold in the fast and two slow P‐light chains. After prolonged, moderate cycling activity phosphate content was only slightly increased in the three P‐light chains. These data suggest that, unlike animal skeletal muscle, myosin light chain kinase and phosphatase activities are similar in human fast and slow muscle fibres.
Direct observation of the immediate electron donor to chlorophyll‐a+II(P‐680+) in oxygen‐evolving photosystem II complexes Resolution of nanosecond kinetics in the UV
Authors: Gerken S. , Brettel K. , Schlodder E. , Witt H.T.
Published: July 2002

Flash‐induced absorption changes in the UV have been monitored with nanosecond time resolution in oxygen‐evolving photosystem II complexes fromSynechococcussp. At 260 nm, the oxidation of the immediate donor to Chl‐a+II(P‐680+) in the 10–500 ns range could be observed directly. The difference extinction coefficient for its oxidation is estimated to be 6000–8000 M−1·cm−1at 260 nm. The observed kinetics for the oxidation of the donor is identical with the reduction kinetics of Chl‐a+IIas monitored at 824 nm. At 320 nm, the reduction of QAwas found to be faster than 1 ns.
Triton X‐100 reacts with chlorophyll in the presence of chlorophyllase
Authors: Michalski T.J. , Bradshaw C. , Hunt J.E. , Norris J.R. , Katz J.J.
Published: July 2002

Chlorophyllase (chlorophyll chlorophyllidohydrolase, EC 3.1.1.14) catalyses the transesterification of chlorophylls with the surfactant Triton X‐100, which is widely used in the preparation and study of this enzyme. The preparation and some properties of water‐soluble tritonyl chlorophyllide esters are described. A mechanism for the role of Triton X‐100 as an inhibitor in chlorophyllase‐catalyzed hydrolysis and transesterification of chlorophylls is proposed. Bacteriochlorophylaalso has been employed as a substrate for green plant chlorophyllase.
Association of calpains 1 and 2 with protein kinase C activities
Authors: Savart Michel , Belamri Mohammed , Pallet Véronique , Ducastaing André
Published: July 2002

Calpains 1 and 2 co‐eluted with protein kinase C activities after hydrophobic (phenyl‐Sepharose) and anion‐exchange (Mono Q) chromatographies of a 100 000 × g supernatant which was defined as cytosol. After centrifugation of the cytosol at 200 000 × g for 16 h, the major part of calpain 1 and of its associated protein kinase C activity was recovered in the pellet, when the major part of calpain 2, also associated to a protein kinase C activity, was present in the resulting supernatant. Polyacrylamide gel electrophoresis of the fractions eluted from the Mono Q column, which contained calpains 1 or 2 and their associated protein kinase C activities, revealed two main bands with a molecular mass of 80 and 28 kDa.
The photobiocatalytic system: Inorganic semiconductors coupled to bacterial cells
Authors: Krasnovsky A.A. , Nikandrov V.V.
Published: July 2002

Considering the evolutionary pathways of solar energy conversion, we suggested that some mineral components of the earth's crust might have been capable of electron phototransfer coupled to the metabolic chains of primary heterotrophic cells. We observed a peculiar type of this process when light‐exposed particles of titanium dioxide or some other minerals initiated an electron transfer from organic electron donors toClostridium butyricumbacterial cells, with hydrogen being evolved as a result of intra‐ and extracellular activity of hydrogenase. The coupling of mineral photocatalysts to bacterial cells may be regarded as a way to create a new type of photobiocatalytic system.
Bile salt‐stimulated lipase in human milk: Evidence for its synthesis in the lactating mammary gland
Authors: Bläckberg Lars , Ängquist Karl-Axel , Hemell Olle
Published: July 2002

Human milk contains many enzymes and other biologically active proteins. One of the enzymes, the bile salt‐stimulated lipase, constitutes as much as 1% of the milk proteins. Its importance for efficient utilization of milk lipids by the breast‐fed infant is now well established. However, whether the lipase protein is a product of protein synthesis within the mammary gland has up till now been an unanswered question. Using biopsy material from lactating human mammary gland we have now demonstrated that the enzyme is synthesized within the gland. This was done by immunoprecipitation of [35S]methionine‐labelled protein from tissue pieces. By activity determination we could also determine the amount of enzyme stored in the gland. It was concluded that bile salt‐stimulated lipase accounted for 1.3 μg/mg tissue protein. Finally, from this figure it could be calculated that about 10–15% of the total protein present in the tissue was milk protein.
N‐terminal sequence analysis of the 8 kDa protein inChlamydomonas reinhardiiLocalization of the phosphothreonine
Authors: Dedner Norbert , Meyer Helmut E. , Ashton Chris , Wildner Günter F.
Published: July 2002

A phosphorylated 8 kDa protein ofChlamydomonas reinhardiithylakoids has been isolated and its N‐terminal amino acid sequence determined by gas‐phase sequencing. The sequence analysis of the 48 amino acid residues revealed that this protein is about 50% homologous to the psb H gene products of higher plants. In contrast to them, it contains an insert of seven amino acid residues (Ser‐5 to Lys‐11). The first threonine residue was phosphorylated as determined by32P detection during sequencing and also by analysis of the modified degradation products in the chemical reaction of the Edman degradation process. This latter method allows the identification of phosphorylated threonine residues without radiolabelling the protein.
Role of N‐linked oligosaccharides attached to human renin expressed in COS cells
Authors: Hori Hitoshi , Yoshino Teruhiko , Ishizuka Yasuyuki , Yamauchi Takeshi , Murakami Kazuo
Published: July 2002

One or both of two putative N‐glycosylation sites (at asparagine‐5 and ‐75) of human renin was eliminated by amino acid replacement of the asparagine residue with an alanine residue using site‐directed mutagenesis. The three glycosylation‐deficient renins (Asn‐5, Asn‐75, Asn‐S and ‐75 mutants) were expressed in COS cells and secreted into the conditioned media. The secreted amounts of the three mutants were different from one another, although the mutant and wildtype renins had practically the same specific activity. An Asn‐5 and ‐75 mutant which did not contain any glycosylation sites was unstable in the medium, suggesting that the N‐linked oligosaccharides play an important role in stabilization of human renin.
Biosynthesis of psoralens Psoralen 5‐monooxygenase activity from elicitor‐treated Ammi majus cells
Authors: Hamerski Daria , Matern Ulrich
Published: July 2002

Microsomes prepared from cultured Ammi majus cells that had been challenged for 14 h with an elicitor derived from the cell walls of Phytophthora megasperma f.sp. glycinea (Pmg) converted psoralen to bergaptol (5‐hydroxypsoralen) in the presence of NADPH and oxygen. The enzymatic activity was characterized as an inducible cytochrome‐P‐450‐dependent monooxygenase associated with the endoplasmic reticulum. All of the steps involved in bergapten (5‐methoxypsoralen) biosynthesis in Ammi majus have now been demonstrated in vitro. The results suggest that bergaptol and not hydroxymarmesin in the precursor of bergapten.
Light scattering changes and protein distortion in the bacteriorhodopsin during the photocycle
Authors: Czégé József
Published: July 2002

A change in light scattering was detected during the photocycle of the purple membrane. A systematic study of the pH, viscosity and photoselection dependence of scattering kinetics is given. From the experimental data it follows that purple membranes are bent, depending on the pH, and that the extent of bending changes during the photocycle is due to the functional protein. A theoretical treatment is also given. The model explains all the experimental data and, as an important consequence, calls attention to the fact that exact kinetic measurements cannot be performed without immobilizing the purple membranes.
Differential regulation of μ‐opiate receptors in heroin‐ and morphine‐dependent rats
Authors: Bolger G.T. , Skolnick P. , Rice K.C. , Weissman B.A.
Published: July 2002

Rats made dependent on heroin and morphine exhibit both qualitative and quantitative differences in the characteristics of radioligand binding to μ‐opioid receptors in the central nervous system. In brain membranes prepared from control animals, [3H]dihydromorphine (DHM) binding was best described by a two‐site model, while in morphine‐dependent rats, [3H]DHM binding was best described by a single‐site model. In contrast, [3H]DHM binding to membranes from heroin‐dependent animals was best described by a two‐site model, with an increased density of the high‐affinity, and no change in the low‐affinity population compared to controls. Furthermore, both the number of binding sites for [3H]DAGO (a ligand that selectively labels a population of high‐affinity μ‐opiate receptors) and the sensitivity of [3H]DHM to sodium ions was increased in heroin; but not in morphine‐dependent rats. These studies demonstrate that opiate receptors are differentially regulated in heroin‐ and morphine‐dependent animals. Such neurochemical changes in μ‐opiate receptors may underlie differences in the behavioral and pharmacological profiles of heroin and morphine reported in man.
80% of muscarinic receptors expressed by the NB‐OK 1 human neuroblastoma cell line show high affinity for pirenzepine and are comparable to rat hippocampus M1 receptors
Authors: Waelbroeck Magali , Camus Jean , Tastenoy Michèle , Christophe Jean
Published: July 2002

The NB‐OK 1 human neuroblastoma cell line expressed muscarinic cholinergic receptors that could be labeled with N‐[3H]methylscopolamine (a nonselective antagonist). 80% of these receptors showed high affinity for pirenzepine, i.e. belonged to the M1 subtype found in neuronal tissues. Their binding properties were identical to those of rat hippocampus M1 receptors, and differed from those of rat pancreas and heart muscarinic receptors. The remaining (20%) muscarinic receptors showed low affinity for pirenzepine and AF‐DX 116, being therefore of an M2β (or B) subtype, and were similar to rat pancreatic receptors.
Leukotriene C4 inhibits ATP‐dependent transport of glutathione S‐conjugate across rat heart sarcolemma Implication for leukotriene C4 translocation mediated by glutathione S‐conjugate carrier
Authors: Ishikawa Toshihisa
Published: July 2002

Sarcolemmal vesicles prepared from rat heart exhibited ATP‐dependent uptake of S‐(2,4‐dinitrophenyl)glutathione (DNP‐SG), which obeyed Michaelis‐Menten kinetics with an apparent K
m of 21 μM for DNP‐SG and a V
max of 0.27 nmol · 10 min−1 · mg protein−1. Several model glutathione S‐conjugates inhibited DNP‐SG uptake, but leukotriene C4 inhibited uptake much more significantly even at lower concentrations (competitive inhibition, K
i = 1.5 μM). However, leukotrienes D4 and E4, which lack the γ‐glutamyl moiety, were less effective. The results suggest that the ATP‐dependent transport system has a high affinity for leukotriene C4, and may be responsible for the translocation of this compound.
Mutation in phenol‐type herbicide resistance maps within thepsbA gene inSynechocystis6714
Authors: Ajlani G. , Meyer I. , Vernotte C. , Astier C.
Published: July 2002

ASynechocystis6714 mutant resistant to the phenol‐type herbicide ioxynil was isolated and characterized. Sensitivity to DCMU and atrazine was measured in whole cells and isolated thylakoids. The mutant presents the same sensitivity to atrazine as the wild type and a slightly increased sensitivity to DCMU. A point mutation has been found at codon 266 in thepsbAI coding locus (AAC to ACC) resulting in an amino acid change from asparagine to threonine in the D1protein.