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Biomedical subjects

M Wolf

Publications and source records attributed to M Wolf.

At least 469 records · Page 26Linked to original sources
PubMed1985

The formation of [3H]inositol phosphates in human platelets by palmitoyl lysophosphatidic acid is blocked by indomethacin.

The intracellular Ca2+ thresholds for platelet shape change and aggregation by A23187 and palmitoyl lysophosphatidic acid were approximately 350 and 750 nM, respectively, as estimated using quin2. The similar thresholds for these two agonists imply they activate platelets through a similar mechanism. In the absence of cyclooxygenase inhibitors, both agents induce the formation of [3H]inositol phosphates, reflecting the activation of phospholipase C. This activation of phospholipase C is blocked by the cyclooxygenase inhibitor indomethacin. It is suggested that platelet activation by palmitoyl lysophosphatidic acid involves an initial mobilization of intracellular Ca2+ with subsequent activation of phospholipase A2; the arachidonic acid metabolites formed then stimulate phospholipase C.

Blood Platelets↗
PubMed1985

Mechanism of phorbol diester-induced regulation of surface transferrin receptor involves the action of activated protein kinase C and an intact cytoskeleton.

Phorbol diesters are tumor-promoting agents that cause differentiation of HL60 human leukemic cells and concomitantly regulate surface transferrin receptors. Regulation of transferrin receptors by phorbol diesters involves receptor internalization in association with increased receptor phosphorylation (hyperphosphorylation). The intracellular mechanism of action of phorbol diester involves binding to and activation of the Ca2+-phospholipid-dependent protein kinase (protein kinase C). Present studies comparing results obtained with whole cells and those from a cell-free system reconstituted from purified protein kinase C and transferrin receptor components have revealed that the transferrin receptor is phosphorylated by protein kinase C activated by phorbol esters. Following tryptic digestion and two-dimensional separation of phosphopeptides of phosphorylated transferrin receptors, two major and several minor phosphoserine-containing fragments are resolved. These fragments are identical whether transferrin receptor is phosphorylated in whole cells incubated with phorbol diesters or following phosphorylation of affinity immobilized transferrin receptor in the in vitro reconstitution system. Phosphoamino acid analysis of these fragments indicates that serine is the only amino acid phosphorylated in whole cells or in the cell-free system. In addition, colchicine is shown to inhibit in a dose-dependent manner phorbol diester-induced internalization but not hyperphosphorylation of the surface transferrin receptor in whole cells. This inhibition is specific for colchicine since inactive beta- and gamma-Lumicolchicine have no such effect, while taxol reverses the inhibition. These results indicate that the phorbol diester-mediated process of down-regulation of the surface transferrin receptor is associated with phosphorylation of the receptor by activated protein kinase C and requires an intact cytoskeleton to affect receptor internalization.

Cell Line↗
PubMed1985

On the significance of true trisomy 20 mosaicism in amniotic fluid culture.

Nine new cases of prenatally detected true mosaic trisomy 20 (T20) are reported. In three instances the fetuses were aborted. One fetus showed multiple malformations associated with a high percentage of T20 cells among amniotic fluid (AF) cells and fibroblasts of different fetal tissues. In two other fetuses only a slight facial dysmorphy was seen which was accompanied by a low percentage of T20 cells among AF cells. In five instances the pregnancies were carried to term, and normal somatic and psychomotor development of the children has been observed, in one case up to the age of 24 months. In one case the pregnancy is continuing. The T20 cells were not detected among cultured lymphocytes of these children. A review of the hitherto known cases of prenatally detected mosaic T20 indicates a relationship between the prenatal findings and the fetal development. This may serve as a provisory basis for genetic counselling: in the case of a percentage above 50% of T20 cells among AF cells there seems to be a risk of about 50% for the fetus to be affected by severe anomalies. However, in cases of a prenatally detected mosaic T20 with a percentage equal to or less than 50, fetal or congenital malformations have not been observed among 23 individuals so far examined.

Adult↗
PubMed1985

Inhibition of interleukin 2 production by prostaglandin E2 is not absolute but depends on the strength of the stimulating signal.

In view of the eminently important role of interleukin-2 (IL-2) in T-cell responses, and in view of reports about immune stimulatory effects of PGE2, we reinvestigated the question whether PGE2 inhibits IL-2 production. It was found that PGE2 does not inhibit IL-2 production in murine spleen cell cultures after optimal stimulation (5 micrograms/ml concanavalin A) but does inhibit at suboptimal stimulation conditions. The failure of PGE2 to inhibit IL-2 production at optimal concanavalin A concentration was demonstrated by two independent IL-2 assays namely by the co-stimulator assay and by the proliferation of IL-2-dependent T-cell clone W-2. Our observations indicated that the inhibitory effect of PGE2 depends on the strength of the stimulating signal. IL-2 production in cultures with 5 micrograms/ml concanavalin A was also not suppressed by PGE1, by prostaglandin D2, thromboxane B2 (T X B2), and prostaglandin F2.

Animals↗
PubMed1985

"Shear induced platelet activation"--a critical reappraisal.

Platelets were found to be stimulated by high shear exposure for 5 minutes. Using a new technique, shear stresses up to 255 N/m2, acting for pathophysiological relevant intervals of milliseconds did not elicit active release of beta-TG, beyond the amount explained by LDH-monitored passive lysis. Neither the plasma level of ionized calcium (citrate vs heparin anticoagulation), nor a potent platelet inhibiting agent like PgI2 (20 nM) did significantly alter platelet responses to short acting high shear stress. Ultrastructural signs of activation could largely be suppressed by adding ADP-scavengers. Direct "shear induced platelet activation" appears rather unlikely and mostly reducible to secondary biochemical activation by mediators, probably adenine nucleotides, from a small percentage of passively shear-destroyed platelets. The extent of this secondary activation is largely a matter of experimental conditions.

Adenosine Diphosphate↗
PubMed1985

The clinical significance of alpha 1-antitrypsin-elastase (alpha 1AT-ELP) and alpha 2-antiplasmin-plasmin (alpha 2AP-PL) complexes for the differentiation of coagulation protein turnover: indications for plasma protein substitution in patients with septicaemia.

In inflammation, particularly in septicaemia, complex coagulation disorders may lead to a dangerous haemorrhagic diathesis. The conventional concept for this syndrome called DIC implicates the occurrence of active thrombin in the circulation, which may be followed by hyperfibrinolysis due to plasmin formation. In this study data are presented suggesting an important role for a third proteolytic system, granulocytic elastase. The complexes of plasmin and elastase with their specific inhibitors, alpha 2-antiplasmin-plasmin (alpha 2AP-PI) and alpha 1-antitrypsin-elastase (alpha 1AT-ELP) were determined immunologically. The alpha 1AT-ELP appears mainly in gram-negative septicaemia, particularly in meningococcal disease. The estimation of alpha 2AP-PI and alpha 1AT-ELP, together with a method for the detection of the antithrombin III--thrombin complex which remains to be established, is a suitable tool for for the differential diagnosis of the consumption of coagulation proteins. The assumption that at least three proteolytic systems participate in the development of the haemorrhagic diathesis during inflammation leads to the concept of a broad, comprehensive substitution therapy with e.g. concentrates of AT III, PPSB, or fresh frozen plasma. The aim of this treatment is to replace not only the consumed procoagulatory factors, but also the lacking inhibitors in order to control this "abnormal proteolysis syndrome".

Adult↗
PubMed1985

Antithrombin Milano: a new variant with monomeric and dimeric inactive antithrombin III.

A qualitative defect of antithrombin III (AT III) has been demonstrated over three generations in eight members of an Italian family by the discrepancy between a normal amount of antigen and decreased antithrombin and anti-Xa activity in the presence or in the absence of heparin. By two-dimensional immunoelectrophoresis in the absence of heparin, two peaks of AT III were present in all patients' plasma. AT III was purified from normal and propositus plasma by sulfate dextran precipitation followed by heparin affinity chromatography. The elution profile of the patient's AT III was abnormal and allowed the separation of two populations of AT III, normal and abnormal. The first fraction (normal AT III) contained AT III activity, migrated as a single peak by two-dimensional immunoelectrophoresis and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), demonstrated a single band with a molecular weight (mol wt) identical to that of normal AT III (60,000). Conversely, the last fraction, devoid of AT III activity, migrated as a single abnormal peak by two-dimensional immunoelectrophoresis in the absence of heparin. By SDS-PAGE, two bands were observed: one with a mol wt of 60,000 and a second one with a mol wt of 120,000. Western blots clearly demonstrated cross-reactivity of the 120,000 and 60,000 mol wt bands with monospecific antisera to human AT III. Reduction of the 120,000 mol wt band converted it to a single 60,000 mol wt band, suggesting the presence of an abnormal dimeric form of AT III. The name AT III Milano is proposed for this new variant.

Adult↗
PubMed1984

A new method for the estimation of protein C by ELISA.

A new solid phase enzyme-linked immunosorbent assay (ELISA) was developed for the quantitation of human protein C antigen. Anti-protein C F(ab')2 fragments were adsorbed to polystyrene plates. The binding of serial dilutions of control or test plasma, containing protein C, was detected by incubation with peroxidase-labeled anti-protein. C-IgG followed by the addition of hydrogen peroxyde and 0-phenylenediamine. This ELISA is specific, sensitive (detection limit: 0.02%) and accurate (variation coefficient: 3 to 10%). When results are compared to those obtained by the Laurell technique (electroimmunodiffusion, EID), the correlation coefficient is 0.95 in all tested plasmas. Protein C antigen was measured by ELISA and EID in plasma from 40 controls, 14 patients with congenital protein C deficiency, 15 patients with liver cirrhosis and 40 dicoumarol-treated cases. In normal plasma, protein C ranged from 70 to 126%. In congenital deficiency, protein C was between 35 and 58% in 13 cases and 9% in one of them. In patients with liver cirrhosis and dicoumarol-treated cases, levels of protein C antigen were compared to those of other vitamin K dependent factors, i.e. Factors II and IX measured by EID and Factor X assayed by EID and ELISA. In liver cirrhosis, the amount of protein C was significantly lower than that of Factors II, IX and X. In short-term and long-term dicoumarol-treated patients, the highest correlation (r = 0.72) was observed between protein C and Factor X levels. In the plasma of patients undergoing oral anticoagulant therapy, protein C decreased more rapidly than Factors X or II and migrated in presence of calcium as a double peak, one with a normal mobility and one more anodal corresponding to the non carboxylated form of protein C.

Antigens↗
PubMed1984

The inhibition of drug metabolism by cimetidine in patients with liver cirrhosis.

The effect of cimetidine treatment, 1 g daily over 6 days, on the disposition of theophylline was studied in nine patients with liver cirrhosis and in nine patients without liver disease. Plasma elimination half-life tended to increase from 14.6 +/- 8.2 h to 24.3 +/- 14.1 h in the cirrhotic patients (P greater than 0.05) and from 8.3 +/- 4.2 h to 10.3 +/- 4.1 h in the control patients (P less than 0.05). Total plasma clearance decreased from 0.50 +/- 0.23 ml/kg/min to 0.41 +/- 0.21 ml/kg/min (P less than 0.05) in the cirrhotics and from 0.77 +/- 0.34 ml/kg/min to 0.58 +/- 0.18 ml/kg/min (P less than 0.05) in the controls. Pretreatment clearance values were also significantly reduced in the cirrhosis group. No change was observed in the volume of distribution of theophylline. The degree of inhibition of theophylline metabolism did not depend on whether the patients were smokers, or whether they had low pretreatment clearance values. In liver cirrhosis, inhibition of drug metabolism by cimetidine varies widely and is unpredictable in the individual patient.

Adult↗
PubMed1984

Protein kinase C: rapid enzyme purification and substrate-dependence of the diacylglycerol effect.

Protein kinase C has been purified by a rapid method resulting in a high-yield, stable enzyme preparation. The catalytic and regulatory properties of this enzyme preparation were characterized employing histone H1 and HMG8, a proteolytic fragment of H1. The enzyme had a lower Km for HMG8, and was stimulated more effectively by diacylglycerol and phorbol esters in the presence of this substrate. Furthermore, these activators markedly increased the Km for HMG8 but not for H1. Protein kinase C and cyclic AMP-dependent protein kinase phosphorylate serine residues which are located in different, single tryptic peptides from HMG8.

Animals↗
PubMed1984

Multiple congenital anomalies/mental retardation (MCA/MR) syndrome due to interstitial deletion 1q.

A severely retarded male infant was found to have a previously undescribed multiple congenital anomalies/mental retardation (MCA/MR) syndrome including microdolichocephaly, prominence of metopic suture, coarse scalp hair, epicanthus, anteverted nostrils, micrognathia, posteriorly angulated malformed auricles, preaxial hexadactyly, clinodactyly, camptodactyly, hypospadias, cryptorchidism, inguinal hernias, agenesis of left kidney, and pyloric stenosis. This syndrome was due to an interstitial del(1)(q25.2q31.2) associated with a paracentric inv(1)(q31.2q44).

Abnormalities, Multiple↗
PubMed1984

Image quality of an image-intensifier fluorographic system.

For an image-intensifier fluorographic system, all essential image-quality parameters (such as MTF, noise Wiener spectrum, sensitivity, and characteristic curve) were determined. The results are in good agreement with theoretical considerations and allow a specification of the influence of the system's components on image quality. Film noise especially, because of the small image format, is of much more importance than had been assumed. A formula for the adjustment of system sensitivity (optimum input dose) has also been derived.

Fluoroscopy↗