bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expiratory flow limitation in morbidly obese postoperative mechanically ventilated patients
Authors: Koutsoukou A. , Koulouris N. , Bekos B. , Sotiropoulou C. , Kosmas E. , Papadima K. , Roussos C. 
Published: September 2004

Although obesity promotes tidal expiratory flow limitation (EFL), with concurrent dynamic hyperinflation (DH), intrinsic PEEP (PEEPi) and risk of low lung volume injury, the prevalence and magnitude of EFL, DH and PEEPi have not yet been studied in mechanically ventilated morbidly obese subjects.In 15 postoperative mechanically ventilated morbidly obese subjects, we assessed the prevalence of EFL [using the negative expiratory pressure (NEP) technique], PEEPi, DH, respiratory mechanics, arterial oxygenation and PEEPi inequality index as well as the levels of PEEP required to abolish EFL.In supine position at zero PEEP, 10 patients exhibited EFL with a significantly higher PEEPi and DH and a significantly lower PEEPi inequality index than found in the five non‐EFL (NEFL) subjects. Impaired gas exchange was found in all cases without significant differences between the EFL and NEFL subjects. Application of 7.5 ± 2.5 cm H2O of PEEP (range: 4–16) abolished EFL with a reduction of PEEPi and DH and an increase in FRC and the PEEPi inequality index but no significant effect on gas exchange.The present study indicates that: (a) on zero PEEP, EFL is present in most postoperative mechanically ventilated morbidly obese subjects; (b) EFL (and concurrent risk of low lung volume injury) is abolished with appropriate levels of PEEP; and (c) impaired gas exchange is common in these patients, probably mainly due to atelectasis.
Thermostability of a Nuclear‐Targeted Luciferase Expressed in Mammalian Cells
Authors: Michels Annemieke A. , Nguyen Van Trung , Konings Antonius W. T. , Kampinga Harm H. , Bensaude Olivier 
Published: September 2004

Protein denaturation and aggregation are most likely the cause for the noxious effects of heat shock. There are some indications that the nucleus is one of the most sensitive cellular compartments. To test the possibility that the intranuclear microenvironment might be detrimental to the heat stability of proteins, we compared the in situ thermal stability of a reporter protein localized in the nucleus or in the cytoplasm. A recombinant firefly (Photynus pyralis) luciferase carrying a point mutation in the C‐terminal domain remains in the cytoplasm (cyt‐luciferase). A nuclear localization sequence was fused to the N‐terminal domain of cyt‐luciferase; the resulting nuc‐luciferase was efficiently targeted to the cell nucleus.In both cases, decreased luciferase activity and solubility were found in lysates from heat‐shocked cells. These characteristics were taken as an indication of thermal denaturation in situ. The heat‐inactivated luciferases were partially reactivated during recovery after stress, indicating the capacity of both the cytoplasmic and nuclear compartments to reassemble proteins from an aggregated state.Although both the nuc‐ and the cyt‐luciferases were heat inactivated at similar rates in vitro, nucluciferase was more susceptible to thermal denaturation in situ compared to cyt‐luciferase. This observation suggests that the microenvironment of an intracellular compartment may modulate the thermal stability of proteins. The local concentration might be one element of this microenvironment affecting the heat‐stability of proteins.In cells made thermotolerant by a priming shock, the thermal inactivation of the recombinant luciferases occurred at a slower rate during a second challenging stress. However, this decreased thermal sensitivity was less pronounced for the nuc‐luciferase (threefold) than for the cyt‐luciferase (sevenfold). The nuclear luciferase might become a useful tool to investigate the action of molecular chaperones in the nucleus.
The Handedness of the Subunit Arrangement of the Nicotinic Acetylcholine Receptor from Torpedo californica
Authors: Machold Jan , Weise Christoph , Utkin Yuri , Tsetlin Victor , Hucho Ferdinand 
Published: September 2004

Cross‐linking an α‐neurotoxin with a known three‐dimensional structure and with photoactivatable groups in known positions to native membrane‐bound acetylcholine receptor reveals its quaternary structure, including the handedness of its circular subunit arrangement. Photolabelling with α‐neurotoxin carrying the photoactivatable group at position Lys46 is inhibited by the competitive antagonist (+)‐tubocurarine in a biphasic manner, indicating that it reacts with both α‐subunits that were shown to have different affinities for this antagonist [Neubig, R. R. & Cohen, J. B. (1979) Biochemistry 18, 5464–5475]. Lys46 is located on loop III of the neurotoxin. The other information necessary for the elucidation of the handedness was provided by the recent finding that the central loop of the toxin (loop II) is orientated towards the central pore of the receptor, securing the overall orientation of the bound toxin [Machold, J., Utkin, Y. N., Kirsch, D., Kaufmann, R., Tsetlin, V. & Hucho, F. (1995b) Proc. Natl Acad. Sci. USA 92, 7282–7286].Looking at the receptor from the synaptic side of the postsynaptic membrane, it was concluded that the clockwise subunit arrangement is αH‐γ‐αL‐δ‐β (αH and αL, are the α‐subunits binding (+)‐tubocurarine with high and low affinity, respectively). Its mirror image αL‐γ‐αH‐β‐δ‐could thus be excluded.
Structure/Function Relationships in the Hemoglobin Components from Moray (Muraena Helena)
Authors: Pellegrini Mariagiuseppina , Giardina Bruno , Olianas Alessandra , Sanna Maria Teresa , Deiana Anna Maria , Salvadori Susanna , Di Prisco Guido , Tamburrini Maurizio , Corda Marcella 
Published: September 2004

Concerning the number and type of the hemoglobin components, the moray Muraena helena is characterized by three different phenotypes whose frequencies are nearly identical. Thus, the cathodal component is present in all individuals, whereas one or both of two anodal components may be present in the same phenotype. These components have been separated by chromatography.The oxygen binding properties of the purified hemoglobin components have been studied in the absence and presence of saturating concentrations of ATP or GTP and as a function of pH. The cathodal component shows an intrinsic O2 affinity four times higher than that of both anodal components, a very small Bohr effect and a significant decrease in O2 affinity upon addition of ATP and GTP (three and four times respectively with respect to stripped conditions), the latter being more effective than the former over the entire pH range examined. The anodal components do not appear functionally distinguishable and show the presence of an enhanced Bohr effect (Root effect) that is under the strict control of nucleotide triphosphates ATP, GTP, which, unlike in the cathodic component, exert the same effect on oxygen affinity. The complete sequence of the β chains of the cathodal and of one of the anodal components have been determined.The possible molecular basis of these different functional characteristics are discussed in the light of the globin sequence and of those amino acid residues which are known to be responsible of hemoglobin functional behaviour.
Inhibition of Human Glutathione Reductase by S‐nitrosoglutathione
Authors: Becker Katja , Gui Ming , Schirmer R. Heiner 
Published: September 2004

S‐Nitrosoglutathione (GSNO) represents a major transport form of nitric oxide (NO) in biological systems. Since NO and GSNO have been shown to modulate the function of various proteins, we studied the influence of GSNO and other NO donors on human glutathione reductase (GR). Catalyzing the reaction NADPH + GSSG + H+→ NADP++ 2 GSH, the dimeric flavoprotein GR is the central enzyme of the glutathione redox metabolism.GSNO was found to inhibit crystalline erythrocyte GR in two ways: (a) as a reversible inhibitor GSNO is competitive with glutathione disulfide (GSSG), the Ki being appr. 0.5 mM; (b) as an irreversible inhibitor; after 1 h (3 h) incubation with 1 mM GSNO, GR (2.5 U/ml, representing intraerythrocytic concentrations) was inhibited by 70% (90%). This inhibition depended on the presence of NADPH and could not be reversed by dilution nor by reducing agents. Absorption spectra indicate that the charge‐transfer interaction between Cys63 and the flavin is abolished by this modification. In a GR sample inhibited by 90% with GSNO, the Km values for the substrates GSSG and NADPH were not significantly changed nor did the modification induce oxidase activity of the enzyme.GSNO was found not to be a substrate in the forward reaction of GR. This implies that GSNO is not accounted for by methods which employ GR for determining total glutathione.Incubating isolated GR for 60 min with other NO donors, namely 1 mM sodium nitroprusside or 1 mM S‐nitroso‐N‐acetyl‐dl‐penicillamine (SNAP), resulted in only 25% and 10% inhibition, respectively. This attests to a specific affinity of GSNO to the enzyme.GSNO inhibition patterns comparable to purified authentic GR were obtained for purified recombinant GR, a GR mutant lacking the 15 N‐terminal amino acids including Cys2, and for the enzyme present in diluted fresh haemolysates (0.02 U/ml); in concentrated haemolysates the inhibition was less pronounced. GR of intact erythrocytes was not affected when exposed to GSNO in the medium.Our results suggest that the irreversible inhibition of GR by GSNO involves nitrosylation of Cys63 and/or Cys58 at the catalytic site of the enzyme. To further investigate the mechanism of inactivation we have crystallized GSNO‐modified GR for X‐ray diffraction analysis.
Basic Fibroblast Growth Factor Controls the Expression and Molecular Structure of Heparan Sulfate in Corneal Endothelial Cells
Authors: Schmidt Annette , Skaletz‐Rorowski Adriane , Buddecke Eckhart 
Published: September 2004

Cultured bovine corneal endothelial cells express 5–8 ng basic fibroblast growth factor (bFGF)/mg cell protein and distribute it between the intracellular and pericellular compartment. Confluent cultures retain approximately 80% of the total bFGF intracellularly, whereas 20% is present in the pericellular (trypsin‐releasable) compartment. No bFGF can be detected in the culture medium.The presence of 1–2 ng/ml medium of endogenous or exogenous (human recombinant) bFGF is sufficient to support cell growth. Simultaneously, cells incorporate [35S]sulfate and [3H]glucosamine into the sulfated proteoglycans associated with the cell layer at a rate that is three times higher than in the absence of bFGF.The enhanced proteoglycan synthesis is accompanied by a shift in proteoglycan distribution. In control cells, cell‐associated heparan sulfate accounts for about 30% of the total glycosaminoglycans, whereas under the influence of bFGF the amount of heparan sulfate increases to approximately 60%. At the same time, the molecular structure of the heparan sulfate molecule undergoes bFGF‐specific changes as indicated by the [35S]oligosaccharide pattern generated by heparitinase I degradation. The proportion of [35S]oligosaccharides with greater than six monosaccharides decreases on account of disaccharides and tetrasaccharides under the influence of bFGF. Pretreatment of bFGF with neutralizing antibodies against bFGF abolishes its biological activity.The results suggest a bFGF‐dependent change in the rate of synthesis and structural features of the membrane‐associated heparan sulfate in corneal endothelial cells. The modification of the heparan sulfate structure could influence its bFGF‐binding and antiproliferative activity.
Muscarinic Toxins from the Black Mamba Dendroaspis polylepis
Authors: Jolkkonen Mikael , Van Giersbergen Paul L. M. , Hellman Ulf , Wernstedt Christer , Oras Aldo , Satyapan Nisamanee , Adem Abdu , Karlsson Evert 
Published: September 2004

Three new toxins acting on muscarinic receptors were isolated from the venom of the black mamba Dendroaspis polylepis. They were called muscarinic toxins α, β, and γ (MTα, MTβ, and MTγ), All of the toxins have four disulphide bonds and 65 or 66 amino acids. The sequences of MTα and MTβ were determined. The muscarinic toxins, of which about 12 have been isolated from venoms of green and black mambas, have 60–98% sequence identity with each other, and are similar to many (about 180) other snake venom components, such as α‐neurotoxins, cardiotoxins, and fasciculins. In contrast to the α‐neurotoxins, muscarinic toxins do not bind to nicotinic acetylcholine receptors.The binding constants of MTα and MTβ were determined for human muscarinic receptors of subtypes m1–m5 stably expressed in Chinese hamster ovary cells. The toxins are less selective than the earlier discovered muscarinic toxins from the green mamba Dendroaspis angusticeps.MTα and the muscarinic toxin MT4 from D. angusticeps differ only in a region of three amino acids (residues 31–33), which are Leu‐Asn‐His in MTα and Ile‐Val‐Pro in MT4. This difference causes a pronounced shift in subtype selectivity. MTα has high affinity to all subtypes, with Ki(inhibition constant) values of 23 nM (m1; pKi= 7.64±0.10), 44 nM (m2; pKi= 7.36±0.06), 3 nM (m3: pKi= 8.46±0.14), 5 nM (m4; pKi= 8.32±0.07), and 8 nM (m5; pKi= 8.09±0.07). MT4 has high affinity only to m1 (Ki= 62 nM) and m4 (87 nM) receptors, and low (Ki>1 μM) affinity to m2, m3, and m5. The region at positions 31–33 evidently plays an important role in the toxin‐receptor interaction.MTβ has low affinity for ml and m2 receptors Ki>1 μM) and intermediate affinity for m3 (140 nM; pKi= 6.85±0.03), m4 (120 nM; pKi= 6.90±0.06), and m5 (350 nM; pKi= 6.46±0.01). The low affinity of MTβ may reflect a tendency for spontaneous inactivation.
Characterization of Apolipoproteins B‐100, AI and C from Plasma Lipoprotein in the Goose, Anser anser
Authors: Hermier Dominique , Sellier Nadine , Rousselot‐Pailley Daniel , Forgez Patricia 
Published: September 2004

In this study we have characterized four of the principle goose apolipoproteins and compared their physicochemical properties with human and avian counterparts. Goose ApoB‐100 and ApoAI amino acid compositions were very similar to their chicken and human homologous proteins. The partial N‐terminal sequence from goose ApoAI was 91% and 82% similar to the corresponding duck and chicken proteins, respectively. Most of the observed amino acid changes detected between the ApoAI sequences were amino acid replacements having the same characteristics and could be the result of a single base mutation.The N‐terminal portion of two ApoC‐like apolipoproteins were also studied. Goose ApoCa had an electrophoretic mobility of 0.31 and exhibited a nine‐residue motif that was well conserved between ApoCIII sequences from different species. We therefore suggest that ApoCa is the equivalent of mammalian ApoCIII. The N‐terminal portion of goose ApoCb, the second major ApoC in high‐density apolipoprotein, showed no similarity to proteins previously described in the literature. This protein displayed two isomorphs in alkaline urea gel electrophoresis called ApoCb1 and ApoCb2 with Rf values of 0.36 and 0.39, respectively. A genetic polymorphism was detected in the population whereby 25% of the animals carried only one isomorph and 50% exhibited both ApoCb isomorphs. These frequencies were similar in females and males. The transmission mode of these ApoCb isomorphs was consistent with two segregating alleles from a single codominantly expressed gene.
Synthesis of a Divalent Sialyl Lewis x O‐glycan, a Potent Inhibitor of Lymphocyte‐Endothelium Adhesion
Authors: Maaheimo Hannu , Renkonen Risto , Turunen Juha Pekka , Penttilä Leena , Renkonen Ossi 
Published: September 2004

The recognition of cell‐surface l‐selectin by its carbohydrate ligands causes lymphocytes to roll on capillary endothelium at sites of inflammation. As this primary contact is a prerequisite for extravasation of the leukocytes to the tissue, its inhibition by free oligosaccharides capable of competing with the natural l‐selectin ligands is an attractive therapeutic possibility.The exact structures of the biological ligands of l‐selectin are not yet known, but the principal carbohydrate epitopes share some structural features: they are O‐glycosidically linked mucin‐type oligosaccharides with N‐acetyllactosamine backbone, which is 3′‐sialylated or 3′‐sulfated, 3‐fucosylated and sometimes 6‐ or 6′‐sulfated at the distal N‐acetyllactosamine termini. Multivalency of the ligand, which is believed to enhance the binding, is achieved by a branched polylactosamine backbone or by a clustered array of O‐glycans.We report here enzymic synthesis of a large oligosaccharide fulfilling several of the features characteristic to the l‐selectin ligands: it is a dodecameric O‐glycosidic core‐2‐type oligosaccharide alditol with a branched polylactosamine backbone carrying two distal α‐2,3′‐sialylated and α‐1,3‐fucosylated N‐acetyllactosamine groups (sialyl Lewis x, sialyl Lex). The structure of each saccharide on the synthesis route from disaccharide Galβ1–3GalNAc to the dodecasaccharide alditol was established by several methods including one‐ and two‐dimensional 1H‐NMR spectroscopy. The last step of the synthesis, the α‐1,3‐fucosylation of the 6‐linked arm proceeded sluggishly, and was associated with a noticeable shift in H1 resonance of the GlcNAc residue of the branch‐bearing N‐acetyllactosamine unit.The final synthesis product and its analogs lacking one or both of the fucose residues were tested as inhibitors of l‐selectin‐mediated lymphocyte‐endothelium interaction in vitro in rejecting rat kidney transplant. While the non‐fucosylated O‐glycosidic oligosaccharide alditol did not possess any inhibitory activity, the mono‐fucosylated one (i.e. monovalent sialyl Lex) prevented the binding significantly and the difucosylated dodecasaccharide alditol (i.e. divalent sialyl Lex) was a very potent inhibitor (IC50, inhibitory concentration preventing 50% of binding = 0.15 μM). Besides the multivalency, also the Galβ1–3GalNAc‐ol sequence of the O‐glycosidic core appeared to increase the affinity of the glycan to l‐selectin. This was indicated by parallel inhibition experiments, where a disialylated and difucosylated branched polylactosamine decasaccharide, similar to the divalent dodecasaccharide alditol, but lacking the reduced O‐glycosidic core, was a less effective inhibitor (IC50= 0.5 μM) than the O‐glycosidic dodecasaccharide alditol.
Effects of Climatic Factors Prevailing Prior to Flowering or Subsequent to Boll Setting on Flower and Boll Production and Retention of Cotton in Egypt
Authors: Sawan Z. M. , Hanna L. I. , McCuistion W. L. 
Published: September 2004

AbstractThis study was conducted to investigate the nature of the effects of climatic factors prevailing prior to flowering or subsequent to boll setting on flower and boll production and retention in Egyptian cotton (Gossypium barbadense L.). Two uniform field trials, using the cotton cv. Giza 75, were carried out in 1992 and 1993 at the Agricultural Research Centre, Giza, Egypt. Randomly chosen plants were used to record daily numbers of flowers and bolls during the production stage (68 days in the first season and 62 days in the second season). The daily records of the climatic factors (air temperature, temperature magnitude, evaporation, surface soil temperature, sunshine duration and humidity) were recorded during the entire period of production and the 15 days preceding or succeeding flower opening. The effects of climatic factors on flower and boll production were quantified in non‐limiting management techniques. Relationships in the form of simple and multiple correlations were computed between climatic factors and flower and boll production and retention. The data indicate that evaporation, minimum humidity and sunshine duration were the most effective climatic factors during preceding and succeeding periods on fruit production and retention. The relationship between climatic factors preceding flowering and cotton production generally exceeded the relationship between the factors during the entire and latter periods of production stage. The result was a negative correlation between either evaporation or sunshine duration with flower and boll formation. In addition, a positive correlation was evident between minimum humidity and flower and boll production. The data indicate that low evaporation rate, reduced sunshine duration and high humidity would enhance flower and boll formation. Accordingly, the deleterious effects of climatic factors on cotton production could be minimized through applying appropriate production practices, which would control and adjust the impact of these factors, and this could lead to an important improvement in cotton yield in Egypt.
Nitrogen Fertilization on Rye Pasture: Effect on Forage Chemical Composition, Voluntary Intake, Digestibility and Rumen Degradation
Authors: Ferri C. M. , Stritzler N. P. , Pagella J. H. 
Published: September 2004

AbstractThe effects of nitrogen (N) fertilization of a rye pasture (Secale cereale L.) on the chemical composition of forage and its utilization in vivo and in situ were investigated in winter (W) and early spring (S). Half of the paddock to be assayed was spread with 93 kg urea–N ha−1 (treatment F), and the other half was not fertilized (treatment NF). Each experiment lasted for 17 days; apparent dry matter digestibility in vivo, voluntary dry matter intake (DMI) and digestible DMI were measured on nine rams per treatment. Two rumen cannulated animals per treatment were under the same feeding regime, and used to collect samples of rumen contents. The concentrations of ammonia (NH3) and short‐chain fatty acids and pH were measured in these samples. The offered forage was also incubated in the rumen of three Holstein–Friesian steers to estimate its degradation parameters in situ. Fertilization with N increased total N and decreased dry matter (DM) and non‐structural carbohydrate concentrations in both periods. DMI was reduced by fertilization. The rumen concentrations of NH3 were higher in F than in NF in both periods. In both periods, the effective DM degradability of forage was higher in F than in NF. N fertilization affects chemical composition, voluntary intake and rumen digestion of forage from rye pasture.
Effect of Timing and Nitrogen Fertilizer Application on Winter Oilseed Rape (Brassica napus L.). I. Growth Dynamics and Seed Yield
Authors: Barłóg P. , Grzebisz W. 
Published: September 2004

AbstractThe field experiments conducted on the grey‐brown podzolic soil in the four growing seasons (1998–2001) at Krzeslice Farm, central‐western Poland comprised seven fertilization variants: 80NF + 80CAN; 80CAN + 80CAN; 80AN + 80AN; 80NF + 50CAN + 30CN; 80CAN + 50CAN +30CN; 80AN + 50AN + 30CN (where NF – nitrofos NPK; CAN – calcium‐ammonium nitrate; AN – ammonium nitrate; CN – calcium nitrate) and control (without N) applied in split rates at the beginning of spring regrowth (80 kg N ha−1), stem elongation (80 or 50) and flower buds visible stages (30). The yielding effect of tested fertilization variants was significant in comparison with the control (2.24 t ha−1). The highest mean seed yield (3.64 t ha−1) was collected from 80AN + 80AN and 80CAN + 80CAN variants. Mean values of 4 years indicate that the second N rate division (80 + 50 + 30) decreased yield, although not significantly in comparison with these two N treatments. Plants grown on these treatments have developed different patterns of growth to yield the seeds. These patterns were characterized by very high crop growth rate during flowering (above 21 g m−2 day−1) and negative at maturation (down to −2.5 g m−2 day−1). Plants fertilized with ammonium nitrate (80AN + 80AN) reached maximum growth rate earlier (65 days), which lasted longer (20 days) than plants fertilized with calcium‐ammonium nitrate (71  days lasting 17.5 days). Plants grown on the control treatment reached the highest crop growth rate within 79 days (14.8 g m−2 day−1), which lasted 15 days.