scholarly journals On the mechanism of stimulation of the Na/K pump of LK sheep erythrocytes by anti-L antibody.

1987 ◽  
Vol 90 (1) ◽  
pp. 3-25 ◽  
Author(s):  
P Dunham ◽  
C Anderson
Keyword(s):  
Maximum Velocity ◽  
Kinetic Studies ◽  
Cell Types ◽  
Kinetic Properties ◽  
Sheep Erythrocytes ◽  
Noncompetitive Inhibition ◽  
L Cells ◽  
Significant Stimulation ◽  
K Concentration ◽  
Stimulation Of

Studies were undertaken to explore the mechanism of stimulation of the Na/K pump in LK sheep erythrocytes by anti-L antibody. First, the numbers of functioning pump sites were determined by correlating [3H]ouabain binding with levels of inhibition of the pump. Untreated (control) cells had approximately 41 pumps per cell, and anti-L treatment caused an increase in the number of functioning pumps to approximately 85 per cell. Reducing the intracellular K concentration, [K]c, to near zero caused an increase in the number of pumps in control cells, but not in anti-L cells, such that the numbers of pumps per cell were about the same in the two cell types. These results led to the prediction that Kc is a noncompetitive inhibitor of the pump in control cells, and that anti-L stimulates the pump and increases number of functioning pumps by reducing noncompetitive inhibition by Kc. Kinetic studies were undertaken to test this prediction: activation of the pump by increasing [Na]c was measured at three fixed levels of [K]c. In control cells, the apparent maximum velocity of the pump (J'max) was reduced approximately threefold by raising [K]c from 0.2 to 9 mmol/liter cells, demonstrating noncompetitive inhibition by Kc. In anti-L cells, J'max did not vary with [K]c, which shows that, as predicted, anti-L abolishes the noncompetitive inhibition by Kc. The modification of the kinetic properties of the pumps by the antibody is highly specific in that affinities for Nac and Ko as substrates are unaffected. However, the effect of the antibody on noncompetitive inhibition by Kc does not explain the stimulation of the pump fully since there is significant stimulation at near-zero [K]c.

Interactions of external and internal K+ with K(+)-HCO3- cotransporter of rat medullary thick ascending limb

1996 ◽  
Vol 271 (1) ◽  
pp. C218-C225 ◽  
Author(s):  
A. Blanchard ◽  
F. leviel ◽  
M. Bichara ◽  
R. A. Podevin ◽  
M. Paillard
Keyword(s):  
Maximum Velocity ◽  
Hill Coefficient ◽  
Kinetic Properties ◽  
Thick Ascending Limb ◽  
Medullary Thick Ascending Limb ◽  
Sigmoidal Curve ◽  
K Concentration ◽  
Physiological Variations ◽  
Allosteric Activator

We studied [K+]i and [K+]o, where subscripts i and o refer to intracellular and extracellular, respectively, concentration dependency of the kinetic properties of the electroneutral K(+)-HCO3-cotransport, using suspensions of rat medullary thick ascending limb (mTAL). With the use of nigericin and monensin, [K+]i was clamped at various values, while maintaining [Na+]i = [Na+]o = 37 mM, [HCO3-]i = [HCO3-]o = 23 mM, and pHi = pHo = 7.4. As indicated by 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein HCO3(-)-dependent rates of change in pHi, at constant [K+]i, increasing the magnitude of the outward K+ gradient by varying [K+]o saturated HCO3-efflux with a Michaelis-Menten curve (apparent Michaelis constant for [K+]o = 2 mM, Hill coefficient = 1). On the other hand, increasing [K+]i from 30 to 140 mM, while either [K+]o or the magnitude of the K+ concentration gradient was fixed, saturated HCO3- efflux with a sigmoidal curve and yielded a Hill coefficient of 3.4 and 50% of maximum velocity at 70 mM [K+]i. These results indicate that [K+]i, independent of its role as a transportable substrate for the cotransport with HCO3-, has a role as an allosteric activator of the K(+)-HCO3- cotransporter. Such an allosteric modulation may contribute to the maintenance of net HCO3- absorption despite large in vivo physiological variations of K+ concentration in the medullary interstitium.

Insulin stimulation of protein synthesis in cultured skeletal and cardiac muscle cells

1982 ◽  
Vol 243 (1) ◽  
pp. C81-C86 ◽  
Author(s):  
J. Airhart ◽  
J. A. Arnold ◽  
W. S. Stirewalt ◽  
R. B. Low
Keyword(s):  
Protein Synthesis ◽  
Specific Activity ◽  
Muscle Cells ◽  
Cell Types ◽  
Cardiac Cells ◽  
Cardiac Muscle Cells ◽  
Significant Stimulation ◽  
Chick Heart ◽  
Embryonic Chick Heart ◽  
Stimulation Of

The effects of acute exposure to insulin on protein synthesis were examined in primary, differentiated cultures of embryonic chick heart and skeletal muscle cells. Synthetic rates were calculated using the specific activity of tRNA-bound leucine as precursor, a specific activity that was significantly less than that of extracellular leucine but greater than that of free, intracellular leucine at 0.2 mM external leucine. Insulin did not alter these relationships. Doses of insulin in the physiological range produced significant stimulation of protein synthesis in both cell types. Maximal responses, involving approximately 30% increases in both absolute and fractional rates, were observed at higher insulin concentrations. Significant stimulation by insulin was seen in cardiac cells after only 1 h of insulin treatment, and the effects of the hormone were observed both in the presence and absence of serum in the culture medium.

scholarly journals Kinetic properties and tissular distribution of mammalian phosphomannomutase isozymes

1999 ◽  
Vol 339 (1) ◽  
pp. 201-207 ◽  
Author(s):  
Michel PIRARD ◽  
Younes ACHOURI ◽  
Jean-François COLLET ◽  
Els SCHOLLEN ◽  
Gert MATTHIJS ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
Time Dependent ◽  
Chemical Characteristics ◽  
Kinetic Properties ◽  
Rat Tissues ◽  
Northern Blots ◽  
Carbohydrate Deficient Glycoprotein Syndrome ◽  
Fructose 1,6 Bisphosphate ◽  
Acyl Phosphate ◽  
Stimulation Of

Human tissues contain two types of phosphomannomutase, PMM1 and PMM2. Mutations in the PMM2 gene are responsible for the most common form of carbohydrate-deficient glycoprotein syndrome [Matthijs, Schollen, Pardon, Veiga-da-Cunha, Jaeken, Cassiman and Van Schaftingen (1997) Nat. Genet.19, 88–92]. The protein encoded by this gene has now been produced in Escherichia coli and purified to homogeneity, and its properties have been compared with those of recombinant human PMM1. PMM2 converts mannose 1-phosphate into mannose 6-phosphate about 20 times more rapidly than glucose 1-phosphate to glucose 6-phosphate, whereas PMM1 displays identical Vmax values with both substrates. The Ka values for both mannose 1,6-bisphosphate and glucose 1,6-bisphosphate are significantly lower in the case of PMM2 than in the case of PMM1. Like PMM1, PMM2 forms a phosphoenzyme with the chemical characteristics of an acyl-phosphate. PMM1 and PMM2 hydrolyse different hexose bisphosphates (glucose 1,6-bisphosphate, mannose 1,6-bisphosphate, fructose 1,6-bisphosphate) at maximal rates of ≈ 3.5 and 0.3% of their PMM activity, respectively. Fructose 1,6-bisphosphate does not activate PMM2 but causes a time-dependent stimulation of PMM1 due to the progressive formation of mannose 1,6-bisphosphate from fructose 1,6-bisphosphate and mannose 1-phosphate. Experiments with specific antibodies, kinetic studies and Northern blots indicated that PMM2 is the only detectable isozyme in most rat tissues except brain and lung, where PMM1 accounts for about 66 and 13% of the total activities, respectively.

Processing and Characterization of Recombinant von Willebrand Factor Expressed in Different Cell Types Using a Vaccinia Virus Vector

1992 ◽  
Vol 67 (01) ◽  
pp. 154-160 ◽  
Author(s):  
P Meulien ◽  
M Nishino ◽  
C Mazurier ◽  
K Dott ◽  
G Piétu ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Von Willebrand Factor ◽  
Human Fibroblasts ◽  
Active Form ◽  
Cell Types ◽  
Biologically Active ◽  
L Cells ◽  
Von Willebrand ◽  
Different Cell Types ◽  
Willebrand Factor

SummaryThe cloning of the cDNA encoding von Willebrand factor (vWF) has revealed that it is synthesized as a large precursor (pre-pro-vWF) molecule and it is now clear that the prosequence or vWAgll is responsible for the intracellular multimerization of vWF. We have cloned the complete vWF cDNA and expressed it using a recombinant vaccinia virus as vector. We have characterized the structure and function of the recombinant vWF (rvWF) secreted from five different cell types: baby hamster kidney (BHK), Chinese hamster ovary (CHO), human fibroblasts (143B), mouse fibroblasts (L) and primary embryonic chicken cells. Forty-eight hours after infection, the quantity of vWF antigen found in the cell supernatant varied from 3 to 12 U/dl depending on the cell type. By SDS-agarose gel electrophoresis, the percentage of high molecular weight forms of vWF varied from 39 to 49% relative to normal plasma for BHK, CHO, 143B and chicken cells but was less than 10% for L cells. In all cell types, the two anodic subbands of each multimer were missing. The two cathodic subbands were easily detected only in BHK and L cells. By SDS-PAGE of reduced samples, pro-vWF was present in similar quantity to the fully processed vWF subunit in L cells, present in moderate amounts in BHK and CHO and in very low amounts in 143B and chicken cells. rvWF from all cells bound to collagen and to platelets in the presence of ristocetin, the latter showing a high correlation between binding efficiency and degree of multimerization. rvWF from all cells was also shown to bind to purified FVIII and in this case binding appeared to be independent of the degree of multimerization. We conclude that whereas vWF is naturally synthesized only by endothelial cells and megakaryocytes, it can be expressed in a biologically active form from various other cell types.

The paracaspase MALT1 in psoriasis

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Stephan Hailfinger ◽  
Klaus Schulze-Osthoff
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Transcription Factors ◽  
Skin Disease ◽  
Cell Types ◽  
Cytokine Receptors ◽  
Molecular Scaffold ◽  
Therapeutic Implications ◽  
Stimulation Of

Abstract Psoriasis is a frequent autoimmune-related skin disease, which involves various cell types such as T cells, keratinocytes and dendritic cells. Genetic variations, such as mutations of CARD14, can promote the development of the disease. CARD14 mutations as well as the stimulation of immune and cytokine receptors activate the paracaspase MALT1, a potent activator of the transcription factors NF-κB and AP-1. The disease-promoting role of MALT1 for psoriasis is mediated by both its protease activity as well as its molecular scaffold function. Here, we review the importance of MALT1-mediated signaling and its therapeutic implications in psoriasis.

scholarly journals Effects of Gut Metabolites and Microbiota in Healthy and Marginal Livers Submitted to Surgery

2020 ◽  
Vol 22 (1) ◽  
pp. 44
Author(s):  
Marc Micó-Carnero ◽  
Carlos Rojano-Alfonso ◽  
Ana Isabel Álvarez-Mercado ◽  
Jordi Gracia-Sancho ◽  
Araní Casillas-Ramírez ◽  
...  
Keyword(s):  
Immune Responses ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Cell Types ◽  
Microbial Populations ◽  
Operative Outcomes ◽  
Bidirectional Relationship ◽  
Preclinical And Clinical Studies ◽  
Different Cell Types ◽  
Stimulation Of

Microbiota is defined as the collection of microorganisms within the gastrointestinal ecosystem. These microbes are strongly implicated in the stimulation of immune responses. An unbalanced microbiota, termed dysbiosis, is related to the development of several liver diseases. The bidirectional relationship between the gut, its microbiota and the liver is referred to as the gut–liver axis. The translocation of bacterial products from the intestine to the liver induces inflammation in different cell types such as Kupffer cells, and a fibrotic response in hepatic stellate cells, resulting in deleterious effects on hepatocytes. Moreover, ischemia-reperfusion injury, a consequence of liver surgery, alters the microbiota profile, affecting inflammation, the immune response and even liver regeneration. Microbiota also seems to play an important role in post-operative outcomes (i.e., liver transplantation or liver resection). Nonetheless, studies to determine changes in the gut microbial populations produced during and after surgery, and affecting liver function and regeneration are scarce. In the present review we analyze and discuss the preclinical and clinical studies reported in the literature focused on the evaluation of alterations in microbiota and its products as well as their effects on post-operative outcomes in hepatic surgery.

scholarly journals Amino acid transport in normal and glutathione-deficient sheep erythrocytes

1976 ◽  
Vol 154 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J D Young ◽  
J C Ellory ◽  
E M Tucker
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Cell Types ◽  
The Other ◽  
Acid Transport ◽  
Sheep Erythrocytes ◽  
Uptake Rates

1. Uptake rates for 23 amino acids were measured for both normal (high-GSH) and GSH-deficient (low-GSH) erythrocytes from Finnish Landrace sheep. 2. Compared with high-GSH cells, low-GSH cells had a markedly diminished permeability to D-alanine, L-alanine, α-amino-n-butyrate, valine, cysteine, serine, threonine, asparagine, lysine and ornithine. Smaller differences were observed for glycine and proline, whereas uptake of the other amino acids was not significantly different in the two cell types.

A novel H+ permeability dominating intracellular pH in the early mouse embryo

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1353-1361
Author(s):  
J.M. Baltz ◽  
J.D. Biggers ◽  
C. Lechene
Keyword(s):  
Plasma Membrane ◽  
Intracellular Ph ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Types ◽  
Preimplantation Embryos ◽  
Developmentally Regulated ◽  
Cell Stage ◽  
K Concentration ◽  
Early Mouse

Most cell types are relatively impermeant to H+ and are able to regulate their intracellular pH by means of plasma membrane proteins, which transport H+ or bicarbonate across the membrane in response to perturbations of intracellular pH. Mouse preimplantation embryos at the 2-cell stage, however, do not appear to possess specific pH-regulatory mechanisms for relieving acidosis. They are, instead, highly permeable to H+, so that the intracellular pH in the acid and neutral range is determined by the electrochemical equilibrium of H+ across the plasma membrane. When intracellular pH is perturbed, the rate of the ensuing H+ flux across the plasma membrane is determined by the H+ electrochemical gradient: its dependence on external K+ concentration indicates probable dependence on membrane potential and the rate depends on the H+ concentration gradient across the membrane. The large permeability at the 2-cell stage is absent or greatly diminished in the trophectoderm of blastocysts, but still present in the inner cell mass. Thus, the permeability to H+ appears to be developmentally regulated.

The promotion of flowering in large field-grown Sitka spruce by girdling and stem injections of gibberellin A4/7

1985 ◽  
Vol 15 (1) ◽  
pp. 166-170 ◽  
Author(s):  
J. J. Philipson
Keyword(s):  
Environmental Conditions ◽  
Sitka Spruce ◽  
Large Field ◽  
Significant Stimulation ◽  
Stimulation Of

Mature 14-year-old grafted Piceasitchensis (Bong.) Carr. which were field grown and 6 m tall were given stem injections of gibberellin A4/7 (GA4/7) alone and in combination with girdling. The GA4/7 was applied twice, at 100 or 250 mg per application. GA4/7 alone produced a large and significant stimulation of the numbers of both pollen and seed cones, with means of about 200 pollen and 90 seed cones per tree, and 90% of the clones flowering; both levels of GA4/7 application stimulated flowering to approximately the same extent. The girdling treatment enhanced flowering when environmental conditions facilitated light flowering of the controls, and also increased the response to 100 mg GA4/7. The stimulation of flowering was carried over into the 2nd year after treatment, but only when both girdling and GA4/7 had been applied together.

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