Ep Level Research Articles

The Politicisation of the European Union and the Role of the European Parliament: Opportunities, Risks and Limitations

Politicisation of the EU has become an important subject in debates about the future of the European governance. This paper addresses the distinguished and unprecedented politicisation-push that the EU has been experiencing through the emergence of sovereignty, identity and solidarity conflicts in the context of the poly-crises - from negative referenda outcomes to the global financial and economic crisis as well as against the backdrop of the migration crisis. Politicisation is heavily influencing and substantially re-shaping the EU institutions and the EU-level Civil Society. After theoretically outlining the concepts of constructive vs. destructive politicisation, the paper focusses on the political dynamics in the women’s rights committee of the European Parliament as a highly politicised arena. The chapter addresses in particular the gender specific cooperation and alliances between and within political groups and party federations by analysing the key factors which influence decision-making in the context of the EP, both at plenary and committee level: distribution of seats among political groups, intra-group cohesion and inter-group coalitions.

Novel Role of Glucagon as a Physiological Defender Against Catecholamine Surge Via Its Direct Action on Adrenomedullary Differentiation

The regulatory role of physiological glucagon (Gcg) in the cardiovascular system remains uncertain. Employing a mouse model harboring a functional deficiency of the preproglucagon gene (GCG-null), we found that lack of endogenous Gcg caused hypertension and systolic left ventricular (LV) dysfunction due to abnormal rise in circulating epinephrine (Ep) level, which was completely restored by the supplemental injection of Gcg (Sup-Gcg) or adrenergic β1-receptor blockers. More interestingly, GCG-null exhibited adrenal hypertrophy with the upregulation of phenylethanolamine N-methyltransferase (PNMT), a key enzyme that synthesizes Ep. Gcg directly facilitated mRNA decay via augmentation of enhancer of mRNA decapping protein 4 (EDC4) in a PKA-dependent fashion, thereby suppressing PNMT in adrenal chromaffin cells. Our data unveiled the novel action of Gcg like a circuit breaker against the Ep surge in the context of disease condition.

DECREASING OF ERYTHROCYTES MEMBRANES PLASMALOGENS LEVEL AT THE DIABETES MELLITUS

Introduction. Plasmalogens are important part of glycerophospholipids and plays a role in the tissue development and metabolism. Changing their level shown in coronary heart diseases, peroxysomes disorders, Diabetes Mellitus (DM).Aim. Study the role of plasmalogens in the development of diabetes complication, especially in diabetic nephropathy (DN) presented interest in our study.Material and methods. In 12 healthy subjects (HS) and in 49 patients with DM2 in age 39 – 65 with disease duration from 2 month to 25 years the level of fasting blood glucose (FBG) and HbA1c, plasma triglycerides (TG) content, plasmalogens in blood serum (SP) and erythrocytes membrane (EP) were observed. The stage of DN detected by urine protein excretion level, glomerular filtration rate (GFR), blood urine nitrogen (BUN) and creatinine level. Patients according to GFR and BUN level were selected into the main 3 groups: without proteinuria (BPU), with proteinuria and normal BUN (PU), with proteinuria and higher BUN (CKD).Results. FBG and HbA1c level were significantly higher in all DM patients than HS, by 2.1, p<0.01 and in 1.7, p<0.05 respectively and was comparable between DN groups. TG level were significantly higher by 1.7 times in DM group and shown relationship with severity of DN. SP and EP level were significantly lower in DM group and showed strong linkage between GFR and BUN level and suggest about involvement of plasmalogens into development of DN.Conclusion. In patients with DM SP and EP level significantly decreased, had a strong linkage with GFR, BUN and can reflect the severity of DN.

Intermolecular Interactions in the Mechanism of Skeletal Muscle Sarcoplasmic Reticulum Ca2+-ATPase (SERCA1): Evidence for a Triprotomer

Native membrane sarcoplasmic reticulum (SR) Ca(2+)-ATPase isolated from skeletal muscle (SERCA1) exhibits oligomeric kinetic behavior [Mahaney, J. E., Thomas, D. D., and Froehlich, J. P. (2004) Biochemistry 43, 4400-4416]. In the present study we used quenched-flow mixing, electron paramagnetic resonance (EPR), and chemical cross-linking to probe for intermolecular interactions at physiological (0.1 M) and high (0.4 M) KCl. Exposure of SR membranes to water- and lipid-soluble cross-linking reagents revealed a mixture of SERCA1 oligomeric species consisting mainly of dimers and trimers. Titration of iodoacetamide spin-labeled SERCA1 with AMPPCP in the presence of 10 microM Ca(2+) and 0.1 M KCl revealed high- (K(D) = 45 microM) and low-affinity (K(D) = 315 microM) nucleotide binding sites in a 2:1 ratio, respectively. Raising the [KCl] to 0.4 M increased the fraction of weak binding sites and lowered the K(D) of the high-affinity component (20 microM). Phosphorylation by 10 microM ATP at 21 degrees C and 0.1 M KCl produced an early burst of P(i) production without a corresponding decline in the steady-state phosphoenzyme (EP) level. The steady-state EP level was twice as large as the P(i) burst and received equal contributions from E1P and E2P. Chasing the phosphoenzyme at 0.4 M KCl and 2 degrees C with ADP revealed a biphasic time course of E1P formation with a slow phase that matched the kinetics of the transient EPR signal from the spin-labeled Ca(2+)-ATPase. The absence of a fast component in the EPR signal excludes E1P as its source. Instead, it arises from a slow, KCl-dependent transformation at the start of the cycle which controls the formation of downstream intermediates with an increased mole fraction of rotationally restricted probes. We modeled this behavior with a SERCA1 trimer in which the formation of E1P/E2/E2P from E1ATP/E2P/E1P results from concerted transformations in the subunits coupling phosphorylation (E1ATP --> E1P + ADP) to dephosphorylation (E2P --> E2 + P(i)) and the conversion of E1P to E2P.

Party Groups and Policy Positions in the European Parliament

As the legislative body of the European Union, the European Parliament groups 732 elected representatives from over 170 national political parties from 25 member states. At the EP level, these members are affiliated with seven major party groups representing distinct policy positions. In this paper we provide precise estimates of these policy positions based on expert surveys in addition to characterizing the dimensionality of policy competition in the EP. Our results suggest not only that party groups have identifiable and differentiated positions on multiple issues of policy, but also that these positions group broadly into two orthogonal dimensions: one consisting of classic left-right social and economic issues, and the other related to the powers and scope of EU institutions.

Calcium dependence of Pi phosphorylation of sarcoplasmic reticulum Ca 2+-ATPase at low water content: water dependence of the E 2→E 1 conversion

Enzymes entrapped in reverse micelles can be studied in low-water environments that have the potential of restricting conformational mobility in specific steps of the reaction cycle. Sarcoplasmic reticulum Ca 2+-ATPase was incorporated into a reverse-micelle system (TPT) composed of toluene, phospholipids, Triton X-100 and varying amounts of water (0.5–7%, v/v). Phosphorylation of the Ca 2+-ATPase by ATP required the presence of both water and Ca 2+ in the micelles. No phosphoenzyme (EP) was detected in the presence of EGTA. Phosphorylation by Pi (inorganic phosphate) in the absence of Ca 2+ was observed at water content below that necessary for phosphorylation by ATP. In contrast to what is observed in a totally aqueous medium, EP formed by Pi was partially resistant to dephosphorylation by Ca 2+. However, the addition of non-radioactive Pi to the EP already formed caused a rapid decrease in radiolabelled enzymes, as expected for the isotopic dilution, indicating the existence of an equilibrium (E+Pi↔EP). Phosphorylation by Pi also occurred in TPT containing millimolar Ca 2+ concentrations in a range of water concentrations (2–5% v/v). The substrates p-nitrophenyl phosphate, acetyl phosphate, ATP and GTP increased the EP level under these conditions. These results suggest that: (1) the rate of conversion of the ATPase conformer E 2 into E 1 is greatly reduced at low water content, so that E 2→E 1 becomes the rate-limiting step of the catalytic cycle; and (2) in media of low water content, Pi can phosphorylate both E 1Ca and E 2. Thus, the effect of enzyme hydration is complex and involves changes in the phosphorylation reaction at the catalytic site, in the equilibrium between E 2 and E 1 conformers, and in their specificity for substrates.

Lack of a relationship of elastin peptide level to emphysema assessed by CT scans.

Clinical reports suggest that peptide (EP) concentration may be used as a subclinical marker of pulmonary emphysema. This hypothesis was tested in a clinical study by comparing EP concentration in male emphysematous patients with the level in two control groups, and by exploring the relation of elastin peptide level to high-resolution computed tomography (HRCT) scan emphysema score among emphysematous patients. Serum EP level was determined among male emphysematous patients with at least 20% of emphysema (n = 27) and in two populations of male workers, drawn from epidemiologic studies (227 coal miners and 310 policemen). No difference in elastin peptide concentration was observed between emphysematous patients and control subjects (mean +/- SD = 2.39 +/- 1.18 micrograms/ml in patients versus 2.55 +/- 1.34 micrograms/ml in policemen and 2.59 +/- 1.20 micrograms/ml in coal miners). The correlation of elastin peptide concentration with percentage of pulmonary emphysema was negative and of borderline significance (r = -0.36; p = 0.06). These results cast doubts on the usefulness of elastin peptide level as a predictive marker of pulmonary emphysema.

Retinoic Acid Downmodulates Erythroid Differentiation and GATA1 Expression in Purified Adult-Progenitor Culture

Abstract All-trans retinoic acid (RA) is an important morphogen in vertebrate development, a normal constituent in human adult blood and is also involved in the control of cell growth and differentiation in acute promyelocytic leukemia. We have examined the effects of RA on normal hematopoiesis by using early hematopoietic progenitor cells (HPC) stringently purified from adult peripheral blood. In clonogenetic fetal calf serum-supplemented (FCS+) or -nonsupplemented (FCS-) culture treated with saturating levels of interleukin-3 (IL-3) granulocyte- macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Ep) (combined with c-kit ligand in FCS(-)-culture conditions), RA induces a dramatic dose-dependent shift from erythroid to granulomonocytic colony formation, the latter colonies being essentially represented by granulocytic clones. This shift is apparently not caused by a recruitment phenomenon, because in FCS+ culture, the total number of colonies is not significantly modified by RA addition. In FCS- liquid- suspension culture supplemented with saturating Ep level and low-dose IL-3/GM-CSF, adult HPC undergo unilineage erythropoietic differentiation: Here again, treatment with high-dose RA induces a shift from the erythroid to granulocytic differentiation pathway. Studies on RA time-response or pulse treatment in semisolid or liquid culture show that early RA addition is most effective, thus indicating that early but not late HPC are sensitive to its action. We then analyzed the expression of the master GATA1 gene, which encodes a finger transcription factor required for normal erythroid development; addition of RA to HPC stimulated into unilineage erythropoietic differentiation in liquid culture caused a virtually complete inhibition of GATA1 mRNA induction. These results indicate that RA directly inhibits the erythroid differentiation program at the level of early adult HPC, and may lead to a shift from the erythroid to granulocytic differentiation pathway. This phenomenon is correlated with inhibition of GATA1 induction in the early stages of erythropoietic differentiation.

Retinoic acid downmodulates erythroid differentiation and GATA1 expression in purified adult-progenitor culture

All-trans retinoic acid (RA) is an important morphogen in vertebrate development, a normal constituent in human adult blood and is also involved in the control of cell growth and differentiation in acute promyelocytic leukemia. We have examined the effects of RA on normal hematopoiesis by using early hematopoietic progenitor cells (HPC) stringently purified from adult peripheral blood. In clonogenetic fetal calf serum-supplemented (FCS+) or -nonsupplemented (FCS-) culture treated with saturating levels of interleukin-3 (IL-3) granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Ep) (combined with c-kit ligand in FCS(-)-culture conditions), RA induces a dramatic dose-dependent shift from erythroid to granulomonocytic colony formation, the latter colonies being essentially represented by granulocytic clones. This shift is apparently not caused by a recruitment phenomenon, because in FCS+ culture, the total number of colonies is not significantly modified by RA addition. In FCS- liquid-suspension culture supplemented with saturating Ep level and low-dose IL-3/GM-CSF, adult HPC undergo unilineage erythropoietic differentiation: Here again, treatment with high-dose RA induces a shift from the erythroid to granulocytic differentiation pathway. Studies on RA time-response or pulse treatment in semisolid or liquid culture show that early RA addition is most effective, thus indicating that early but not late HPC are sensitive to its action. We then analyzed the expression of the master GATA1 gene, which encodes a finger transcription factor required for normal erythroid development; addition of RA to HPC stimulated into unilineage erythropoietic differentiation in liquid culture caused a virtually complete inhibition of GATA1 mRNA induction. These results indicate that RA directly inhibits the erythroid differentiation program at the level of early adult HPC, and may lead to a shift from the erythroid to granulocytic differentiation pathway. This phenomenon is correlated with inhibition of GATA1 induction in the early stages of erythropoietic differentiation.

Enalapril and anemia in patients undergoing hemodialysis.

We evaluated the incidence and progression of anemia in a retrospective study of 18 hemodialysis (HD) patients who were receiving enalapril maleate. Patients were divided into 2 groups based on hematocrit (Ht) changes. In Group A (n=6 patients), the Ht decreased more than 5%; in Group B (n=12 patients), there was no significant decrease in Ht. We measured hematological parameters, and concentrations of enalapril and erythropoietin (Ep). Hemolytic and/or iron deficiency anemia were ruled out by hematologic evaluation in Group A. The Ep level was lower during treatment than pre-treatment level in Group A, whereas, there was no significant difference in this parameter in Group B.We recommend that enalapril maleate should be used with caution in patients with a reduced Ht level associated with drug administration. We conclude that enalapril-induced anemia is provoked by the suppression of Ep production.

Water use, wetted soil volume, root distribution and yield of avocado under drip irrigation

The effect of three water use (WU) levels corresponding to 0.3, 0.6 and 0.9 Ep ( Ep=Evaporation “A” pan ) on wetted soil volume, root distribution and yield of avocado cv. Fuerte was investigated over a 5-year period at Chania, Greece. The average amounts of irrigation water applied annually (in addition to rain) for the three WU levels were 238, 553 and 868 mm, respectively. Soil volumes, with a volumetric soil water content percentage (θ) corresponding to a soil water potential ( Ψ s ) higher than −0.1 MPa, increased markedly from 0.3 to 0.6 Ep, and slightly from 0.6 to 0.9 Ep WU levels, being 26.3, 41.7 and 52%, respectively. Deep percolation did not occur at 0.3 Ep, was moderate but acceptable at 0.6 Ep, and high at 0.9 Ep. Root distribution was similar in all treatments. Some 72% of the root system was concentrated in the upper 0.5 m soil layer and within 2 m on either side of the drip line. Root density (RD) increased greatly from 0.3 to 0.6 Ep, and slightly from 0.6 to 0.9 Ep level. RD in relation to θ did not show any notable difference between WU levels. Root growth rate, estimated by the lateral to main root ratio ( r), was higher in a θ range of 20 to 30%, corresponding to a Ψ s , range of −0.05 to −0.3 MPa for the soil in the experiment. Yield at 0.3 Ep was lower than at 0.6 and 0.9 Ep WU levels among which no significant differences were seen. Size of individual fruits and oil content were not significantly different between treatments. When water saving, deep percolation, wetted soil volume, root development, and yield quantity and quality are taken into account, then a WU level of 0.6 Ep can be considered optimal under the conditions of this experiment.

Inhibition of sarcoplasmic reticulum Ca(2+)-ATPase by 2,5-di(tert-butyl)-1,4-benzohydroquinone.

We characterized the interaction of 2,5-di(tert-butyl)-1,4-benzohydroquinone (tBuBHQ) with the sarcoplasmic reticulum (SR) Ca(2+)-ATPase from rabbit fast-twitch skeletal and canine cardiac muscles by examining the effect of this agent on the ATPase reaction. tBuBHQ at less than 10 microM inhibited ATP hydrolysis by both isoforms of Ca(2+)-ATPase by up to 80 and 90%, respectively. The half maximal inhibition of these enzymes was observed at about 1.5 microM tBuBHQ. Thus, this agent potently inhibits the fast-twitch skeletal and slow-twitch skeletal/cardiac isoforms of SR Ca(2+)-ATPase. tBuBHQ at 5-10 microM inhibited the rate of decomposition of the phosphoenzyme intermediate (EP), measured as a ratio between ATPase activity and the EP level in the steady state, by 35-40%. It also inhibited formation of EP by decreasing the rate of Ca2+ binding to the Ca(2+)-deficient, nonphosphorylated enzyme to about 1/8 of the control value. These results indicate that tBuBHQ has at least two sites of action in the reaction sequence for the SR Ca(2+)-ATPase.

Adoptive Immunotherapy With High-Dose Interleukin-2: Kinetics of Circulating Progenitors Correlate With Interleukin-6, Granulocyte Colony-Stimulating Factor Level

Immunotherapy with interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells results in significant tumor regression in patients with advanced cancer. We have investigated the kinetics of circulating erythroid (BFU-E) and granulocytic-macrophage (CFU-GM) progenitors after IL-2 therapy in 11 cancer patients, mainly affected by metastatic melanoma and renal cell carcinoma. Administration of IL-2 from day 1 through day 5 constantly induced a dramatic decrease of the number of circulating BFU-E and CFU-GM, which then showed a striking rebound (up to values fourfold and sevenfold higher, respectively, than the pretherapy levels) on discontinuation of IL-2, ie, from day 5 through day 10. A similar kinetic pattern was observed during and after the second cycle of IL-2 administration. 3[H]-thymidine killing experiments showed that the cycling activity of the progenitors was virtually unmodified in the rebound phases. To explore the mechanism(s) underlying this kinetic pattern, we have analyzed the plasma concentration of several hematopoietic growth factors, including IL-1 beta, IL-3, IL-4, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF, and erythropoietin (Ep). No modifications in the levels of IL-3, GM-CSF, or IL-1 beta were observed, whereas a pronounced increase of IL-6 and G-CSF concentration was monitored, starting at day 3 and peaking at day 5 of treatment (a parallel, but modest, increase of Ep level was also observed). The elevation of IL-6 and G-CSF concentration is directly correlated with and may, at least in part, underlie the subsequent rebound of circulating hematopoietic progenitors. Furthermore, the increase in IL-4 level observed at day 10 of therapy may mediate the eosinophilia gradually starting at this stage of treatment.

Adoptive immunotherapy with high-dose interleukin-2: kinetics of circulating progenitors correlate with interleukin-6, granulocyte colony-stimulating factor level

Immunotherapy with interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells results in significant tumor regression in patients with advanced cancer. We have investigated the kinetics of circulating erythroid (BFU-E) and granulocytic-macrophage (CFU-GM) progenitors after IL-2 therapy in 11 cancer patients, mainly affected by metastatic melanoma and renal cell carcinoma. Administration of IL-2 from day 1 through day 5 constantly induced a dramatic decrease of the number of circulating BFU-E and CFU-GM, which then showed a striking rebound (up to values fourfold and sevenfold higher, respectively, than the pretherapy levels) on discontinuation of IL-2, ie, from day 5 through day 10. A similar kinetic pattern was observed during and after the second cycle of IL-2 administration. 3[H]-thymidine killing experiments showed that the cycling activity of the progenitors was virtually unmodified in the rebound phases. To explore the mechanism(s) underlying this kinetic pattern, we have analyzed the plasma concentration of several hematopoietic growth factors, including IL-1 beta, IL-3, IL-4, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF, and erythropoietin (Ep). No modifications in the levels of IL-3, GM-CSF, or IL-1 beta were observed, whereas a pronounced increase of IL-6 and G-CSF concentration was monitored, starting at day 3 and peaking at day 5 of treatment (a parallel, but modest, increase of Ep level was also observed). The elevation of IL-6 and G-CSF concentration is directly correlated with and may, at least in part, underlie the subsequent rebound of circulating hematopoietic progenitors. Furthermore, the increase in IL-4 level observed at day 10 of therapy may mediate the eosinophilia gradually starting at this stage of treatment.

Impermeability of the ovine placenta to 35S-recombinant erythropoietin.

Controversy exists regarding the placental permeability of erythropoietin (Ep), a glycoprotein hormone that regulates red blood cell production in the fetus, newborn, and adult after tissue hypoxia. The purpose of the current study was to determine the placental permeability of biologically active 35S-labeled human recombinant erythropoietin given by bolus injection into the circulation of the fetal lamb. Specific radioactivity in fetal plasma trichloroacetic acid protein precipitate fractions increased 13-fold from preinfusion levels at 6 h (47 +/- 1.3 to 679 +/- 237 cpm/mL) and thereafter fell progressively until the study was terminated at 45 h. In contrast, maternal trichloroacetic acid protein precipitate fractions demonstrated no detectable increase in radioactivity at any time. Based on the counting precision, a rise in maternal plasma radioactivity of more than 3 cpm/mL would have been detected (i.e. 0.5% of the 582 cpm/mL rise in the fetal protein precipitate counts at six h). Similar data were obtained with simultaneously administered unlabeled human urinary Ep. We conclude that physiologically significant amounts of Ep do not cross from fetus to mother; hence, maternal Ep level functions as a separate indicator of the adequacy of tissue oxygenation in the maternal compartment.

Relation of serum erythropoietin levels to renal excretory function: evidence for lowered set point for erythropoietin production in chronic renal failure.

The relationship of serum erythropoietin (Ep) levels to hematocrit and glomerular (GFR) filtration rate was evaluated in patients with chronic renal disease. The Ep level was measured by radioimmunoassay in 119 blood samples from 48 patients obtained over a period of up to 5 years. Hematocrit values correlated significantly with the GFR, but serum Ep levels did not change with a decline in the GFR. Significant anemia was noted only when the GFR fell below 20 ml/min/1.73 m2. Episodes of spontaneous acute hypoxic stress were observed in six patients with chronic renal failure. Serum Ep levels obtained during these episodes (mean +/- SEM: 273 +/- 76 mU/ml) were tenfold higher than Ep levels during stable steady-state chronic renal failure (26 +/- 6 mU/ml), even though Ep levels were inappropriately low for the degree of anemia in the stable state. Our findings suggest that the tissue oxygenation-Ep-hematocrit feedback mechanism operates at a lower set point in patients with chronic renal failure in comparison with normal subjects.

Two different phosphorylation-dephosphorylation cycles of Na,K-ATPase proteoliposomes accompanying Na+ transport in the absence of K+.

The phosphorylated intermediate (EP) of the Na,K-ATPase proteoliposomes (PL) prepared from the electric eel enzyme is composed of an ADP-sensitive K+-insensitive form (E1P), an ADP- and K+-sensitive form (E*P), and a K+-sensitive ADP-insensitive form (E2P). The composition of the intermediate varied with the cholesterol content of the lipid bilayer. The PL containing less than 30 mol % cholesterol (LCPL) formed E2P-rich EP in the presence of 10 mM Na+ on both sides at 15 degrees C, while the PL containing more than 35 mol % cholesterol (HCPL) formed E*P-rich EP under the same condition. In the presence of ionophore (monensin, nigericin, A23187), the HCPL formed E2P-rich EP as reported in the preceding paper. The turnover rate of Na-ATPase activity (the ratio of Na-ATPase to the EP level) in the LCPL was lower than that in the HCPL, and the addition of 20 microM monensin or A23187 to the HCPL reduced the Na-ATPase activity. The coupling ratio of Na+ influx (cellular efflux):Na+ efflux (cellular influx):ATP hydrolysis was 2.8:1.8:1 in the LCPL, although 1.6:0.6:1 in the HCPL. The coupling ratio of Na+ influx:ATP hydrolysis in the HCPL increased to 2.8:1 in the presence of A23187. Moreover, the increase of ATP concentration enhanced not only the Na-ATPase activity in the LCPL and HCPL with monensin but also the Na+ influx in the LCPL. This ATP enhancement was not found, however, in the HCPL without ionophores. The ADP enhancement of the Na+ influx was not observed in either the HCPL or the LCPL. We conclude from these observations that there are at least two different phosphorylation-dephosphorylation cycles (an E2P cycle and an E*P cycle) in the PL in the absence of K+. The E2P cycle transports three Na+ from the extravesicular (cytoplasmic) to the intravesicular (extracellular) side and two Na+ in the opposite direction per cycle and is similar to the ATP-dependent Na+-Na+ exchange system already reported (Blostein, R. (1983) J. Biol. Chem. 258, 7948-7953; Cornelius, F., and Skou, J. C. (1985) Biochim. Biophys. Acta 818, 211-221). However, the E*P cycle transports one Na+ from the extravesicular to the intravesicular side/cycle and has not yet been previously reported.

Solubilization and separation of Ca 2+-ATPase from the Ca 2+-ryanodine receptor complex

Heavy sarcoplasmic reticulum (SR) preparations of rabbit skeletal muscle, which are enriched in Ca2+-release vesicles from the terminal cisternae (TC) and [3H]ryanodine receptor density, exhibit 60% of the Ca2+-ATPase activity, 58% of the EP level, and 30% of the steady state Ca2+ loading compared to membrane vesicles from the longitudinal SR. The Ca2+-ATPase of TC SR is solubilized and separated from the Ca2+-ryanodine receptor complex in the insoluble fraction on treatment with the detergent C12E9. However, a 50% decrease in receptor density is observed upon removal of the Ca2+-ATPase, suggesting a significant contribution of this protein to maintaining optimal receptor complex density.

Reduced erythropoitein levels as a cause of anaemia in patients with lung cancer

Measurements of erythropoietin (Ep) levels in patients with the anaemia of chronic disorders due to malignant disease have given variable results. This variation may be due to the wide range of malignancies studied and the assay method (whole animal) used. In this study Ep levels were measured, using the foetal mouse liver assay, in 39 patients with lung cancer and 19 controls. Twelve patients had reduced haemoglobin levels (Hb less than 11.5 g/dl for males and 11 g/dl for females) and the features of the anaemia of chronic disorders. Their mean Ep level was 0.21 iu/ml. This was significantly lower than for the normal controls, whose mean value was 0.31 iu/ml (P < 0.02). This data supports the concept that lack of an appropriate Ep response to anaemia is one factor in the genesis of anaemia in malignancy.

Temporal response of immunoreactive erythropoietin to acute hypoxemia in fetal sheep.

Acute hypoxemia was produced in chronically catheterized sheep fetuses to determine the response time necessary to increase plasma immunoreactive erythropoietin (Ep) concentration. Sodium nitrite (0.2 mM) was infused via a fetal vein to induce fetal hypoxemia. The resultant fetal methemoglobinemia was associated with a predictable, incremental decrease in arterial oxygen content. Twelve nitrite infusions were performed in eight fetal sheep preparations (gestational ages 115-146 days). Mean methemoglobin level increased to 33% of total Hb after 1-2 h of NaNO2 infusion. These results were compared to those obtained in nine control studies in eight fetuses in which no change was observed for plasma Ep, arterial oxygen content, PaO2, pHa, or whole blood lactate. In the nitrite infused group, however, a significant and progressive increase in mean plasma Ep level over baseline levels was observed during the 4th and 5th h of hypoxemia (p less than 0.01). This change in Ep was significantly greater compared to the control group. These results, however, were confounded by the concomitant development of a lactic acidemia secondary to the fetal hypoxemia. To examine the theoretic possibility that lactic acidemia may primarily affect fetal Ep levels, an additional group of five fetuses was infused with L-lactic acid for the same time period. Although the decrements in pHa and whole blood lactate levels achieved in these fetuses were in excess of those observed during the nitrite infusions, this possibility was ruled out since no change in fetal plasma Ep levels occurred. We conclude that during the 4th h of acute fetal hypoxemia a predictable, progressive increase in plasma Ep level is observed.(ABSTRACT TRUNCATED AT 250 WORDS)