Monströses, maligne entartetes Neurofibrom am Unterschenkel bei Morbus Recklinghausen

HISTORY

A 65-year-old man had noted a tumor of the right lower leg that had progressively grown over the last twenty years. He had a dyspnoea on insignificant movement and was relatively immobile because of the extent of the tumor. The tumor had been diagnosed as a Klippel-Trenaunay syndrome.

INVESTIGATIONS

Laboratory investigations suggested a hypochromic and microcytic anaemia and an inflammatory constellation. The tumor had no av-fistulas on ultrasonography and angiography, but there were many pathological arteries and tumor nodes. The tumor nodes had been seen also on MRI-biopsy suggested a neurogenic sarcoma.

DIAGNOSIS AND TREATMENT

Amputation of the leg was necessary. The histological diagnosis was neurofibrosarcoma with extensive necrotic areas and Recklinghausen disease. Investigation did not reveal any metastasis. Postoperatively the anaemia regressed and the patient learned to walk with a prosthesis.

CONCLUSIONS

This history shows the problem of separating clearly the two hereditary diseases. Often there is a different clinical picture in everyday life. One must consider the definitely higher risk of malignant tumors of patients with neurofibromatosis. Ultrasonography is a non-invasive method that can provide morphological information on soft parts and pathology of the vessels. It facilitates the classification of such.

[Physiology and pathophysiology of the vascular endothelin system: clinical implications]

The endothelium-derived 21 amino acid peptide endothelin-1 is one of the most potent vasoconstrictors. Endothelin-1 exerts its effects upon a variety of vascular and non-vascular cells through a direct interaction with specific receptors. Beyond its vasoconstrictive action on vascular smooth muscle cells endothelin-1 has mitogenic and pro-inflammatory properties. The present review deals with current experimental and clinical evidence for the involvement of endothelin-1 in several cardiovascular disorders with inflammatory components. We further discuss the potential clinical relevance of the endothelin system and therapeutical perspectives of anti-endothelin strategies in the treatment of cardiovascular disease.

Acute intramural haematoma of the coeliac artery

The report describes a previously healthy 24-year-old women presenting with acute abdominal pain following a hyperextension manoeuvre. The key finding of a continuous bruit with systolic and diastolic components in the epigastric region subsequently led to the diagnosis of an intramural haematoma of the coeliac artery, that caused a subtotal occlusion of the artery. The diagnosis was achieved by both colour-coded duplex sonography and magnetic resonance angiography. The case shows that a conservative management rather than operative reconstruction is justified in an oligo-symptomatic situation with no signs of end-organ damage as in this patient.

Endothelial tissue factor stimulation by proteinase 3 and elastase

In ANCA-associated vasculitis the activation of primed leucocytes by autoantibodies with subsequent release of proteases such as myeloperoxidase (MPO), proteinase 3 (PR3) and elastase is thought to play an important pathogenetic role. Whether these proteases contribute to the vascular lesions by stimulating the procoagulant activity of these cells is unknown. Tissue factor (TF) expression and activity were investigated in human umbilical vein endothelial cells after stimulation with MPO, PR3 and elastase. TF activity was measured using a one-stage clotting assay. Polyclonal antibodies to TF were used to prove specificity. TF mRNA was detected by reverse transcriptase-polymerase chain reaction. PR3 and elastase led to a significant increase in TF mRNA expression and increased activity. The stimulation was not mediated by IL-1. The stimulatory effect of PR3 did not depend on its proteolytic activity (no inhibition by alpha-1-antitrypsin), whereas the effect of elastase was blocked by alpha-1-antitrypsin. MPO had no effect on TF activity. These results show that PR3 and elastase stimulate TF expression in human endothelial cells. In ANCA-associated vasculitis the increased release of proteases may contribute to the development of microthrombi and consecutive necrosis.

Role of increased production of superoxide anions by NAD(P)H oxidase and xanthine oxidase in prolonged endotoxemia

Superoxide anions (O2-) are supposedly involved in the pathogenesis of endothelial dysfunction. We investigated whether the enhanced formation of O2- is involved in the attenuation of endothelium-dependent relaxation induced by lipopolysaccharide (LPS). Rats were injected with LPS (10 mg/kg IP), the aorta was removed after 12 or 30 hours, and generation of O2-, H2O2, and ONOO- was measured using chemiluminescence assays. Protein tyrosine nitration and expression of xanthine oxidase (XO), NAD(P)H oxidase, and manganese superoxide dismutase were determined by Western or Northern blotting, and endothelium-dependent relaxation in aortic rings was studied. LPS treatment increased vascular O2- (from 35+/-2 cpm/ring at baseline to 166+/-21 cpm/ring at 12 hours and 225+/-16 cpm/ring at 30 hours) and H2O2 formation, which was partially sensitive to the NAD(P)H oxidase inhibitor diphenylene iodonium at both time points studied and to the XO inhibitor oxypurinol only 30 hours after LPS treatment. Expression of XO and NAD(P)H oxidase (p22phox, p67phox, and gp91phox) were increased by LPS in a time-dependent manner, as were protein tyrosine nitration and ONOO- formation. LPS also induced expression of the oxidative stress-sensitive protein manganese superoxide dismutase. Endothelium-dependent relaxation was impaired after LPS treatment and could not be restored by inhibition of inducible NO synthase. Inhibition of O2- with superoxide dismutase, oxypurinol, tiron, or the superoxide dismutase mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride did not restore but further deteriorated the relaxation of LPS-treated rings. In summary, treatment of rats with LPS enhances vascular expression of XO and NAD(P)H oxidase and increases formation of O2- and ONOO-. Because removal of O2- compromised rather than restored endothelium-dependent relaxation, a direct role of O2- in the induction of endothelial dysfunction is unlikely. Other mechanisms, such as prolonged protein tyrosine nitration by peroxynitrite (which is formed from NO and O2-) or downregulation of the NO effector pathway, are more likely to be involved.

Thrombin inactivates myosin light chain phosphatase via Rho and its target Rho kinase in human endothelial cells

The role of Rho GTPase and its downstream targets Rho kinase and myosin light chain phosphatase in thrombin-induced endothelial cell contraction was investigated. The specific Rho inactivator C3-transferase from Clostridium botulinum as well as microinjection of the isolated Rho-binding domain of Rho kinase or active myosin light chain phosphatase abolished thrombin-stimulated endothelial cell contraction. Conversely, microinjection of constitutively active V14Rho, constitutively active catalytic domain of Rho kinase, or treatment with the phosphatase inhibitor tautomycin caused contraction. These data are consistent with the notion that thrombin activates Rho/Rho kinase to inactivate myosin light chain phosphatase in endothelial cells. In fact, we demonstrate that thrombin transiently inactivated myosin light chain phosphatase, and this correlated with a peak in myosin light chain phosphorylation. C3-transferase abolished the decrease in myosin light chain phosphatase activity as well as the subsequent increase in myosin light chain phosphorylation and cell contraction. These data suggest that thrombin activates the Rho/Rho kinase pathway to inactivate myosin light chain phosphatase as part of a signaling network that controls myosin light chain phosphorylation/contraction in human endothelial cells.

Increased cellular triglyceride levels in human monocytic and rat smooth muscle cells after lovastatin

Beta-hydroxy-beta-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors reduce plasma LDL cholesterol by upregulating hepatic LDL receptors. However, their effects on lipid metabolism in extrahepatic cells may also contribute to their therapeutic benefit. We examined the effects of lovastatin (LOV) on cellular lipid levels in the human monocytic Mono Mac 6sr and cultured rat smooth muscle cells. In both cell types, LOV produced a dose-dependent increase in cellular triglycerides. This increase was observed in cells grown in the absence of exogenous lipids in the culture medium, but was more pronounced after additions of oleic acid (50 to 200 microM) and VLDL (50 to 200 microg ml-1). In Mono Mac 6sr cells grown in medium containing 10% delipidated FCS for the last 16 h, the LOV-induced rise in triglyceride levels was completely reversed by 2 mM mevalonic acid and was associated with a decrease in cellular cholesterol. However, when cells were maintained in lipoprotein-replete medium, the LOV-induced rise in triglycerides did not correlate with cellular cholesterol. LOV also reduced cellular cholesterol esterification and increased the synthesis of fatty acids and their incorporation into triglycerides and phospholipids. Increased triglyceride levels were also seen in Mono Mac 6sr cells treated with the lanosterol demethylase inhibitor RS-21607 and the acylcoenzyme A:cholesterol acyltransferase inhibitor SaH 58035. Our findings suggest that the LOV-induced triglyceride accumulation involves changes in intracellular cholesterol pools regulating cellular fatty acid concentrations. Although decreased cholesterol levels in cells participating in plaque formation are beneficial, the impact of the herein described shift in intracellular neutral lipid metabolism on other cellular functions warrants further investigation.

[Cellular mechanisms of endothelial endothelin synthesis]

Endothelin-1 is a vasoactive peptide produced by endothelial cells. Endothelin-1 exerts potent vasoconstrictory effects upon vascular smooth muscle cells, and it may play a role in the pathogenesis of several cardiovascular disorders such as atherosclerosis and ischemic conditions. Besides the investigation of its biological effects, knowledge about cellular mechanisms of the synthesis, signal transduction pathway(s) and receptor-mediated actions on target cells is mandatory for the development of pharmacological strategies in the treatment of cardiovascular disease. In this review cellular mechanisms of endothelial endothelin-1 synthesis and release are discussed.

[Physiology and pathophysiology of the endothelin system in cardiovascular diseases]

The endothelins are a family of potent vasoconstrictors and mitogenic agents. Since the isolation of ET-1 in 1988 the worldwide scientific research interest has mushroomed, resulting in considerable knowledge about molecular biology, biochemistry and pharmacological actions of these peptides. A body of evidence has parallelly emerged pointing to their role in some physiological phenomena as well as in the pathophysiology of cardiovascular disease. The future therapeutic use of anti-endothelin strategies may offer clinical benefit in many of these conditions.

Effects of low-dose epinephrine infusion on cardiovascular and renal responses to water immersion in humans

Elevated plasma epinephrine concentrations may impair blood pressure homeostasis and renal sodium and volume excretion in response to central hypervolemia. We studied the effects of a low-dose epinephrine infusion (12 ng/kg/min) on cardiovascular and renal responses to a thermoneutral head-out water immersion in eleven healthy men. Responses to water immersion without epinephrine were characterized by significant suppression of plasma renin activity (PRA), plasma aldosterone concentration, and renal norepinephrine excretion, and an augmentation of natriuresis and diuresis. Epinephrine infusion, which raised mean plasma epinephrine concentration 4.3-fold, slightly increased plasma norepinephrine and renal norepinephrine excretion, markedly stimulated PRA (+66.7%), but decreased plasma aldosterone (-11.7%), and augmented renal sodium and volume excretion. Despite the presence of the epinephrine infusion, water immersion continued both to suppress PRA and aldosterone, and to increase natriuresis and diuresis in a qualitatively similar pattern. During all conditions blood pressure and heart rate remained unchanged. It is concluded that physiologic responses to central hypervolemia are not impaired at stress levels of circulating epinephrine. During epinephrine infusion, despite a concomitant increase in plasma norepinephrine and a stimulation of PRA, blood pressure remained constant in response to water immersion due to an augmentation of natriuresis and diuresis.

Role of epinephrine-induced hypokalemia in the regulation of renin and aldosterone in humans

Circulating epinephrine induces both stimulation of plasma renin activity (PRA) and a decrease in serum potassium concentration. This study was designed to determine the dose-response effects of systemic epinephrine infusion on the relationship of PRA and plasma aldosterone concentration. Twenty-one men with normal blood pressure received either an intravenous infusion of epinephrine at 12.5, 25, and 50 ng/(kg x min) by stepwise increments for 1 hour each or isotonic saline solution. Infusion of epinephrine led to a dose-dependent increase in plasma epinephrine concentration, systolic blood pressure, and heart rate, whereas diastolic blood pressure was decreased. PRA was elevated in a dose-dependent manner, whereas the plasma aldosterone concentration was reduced. During infusion of epinephrine, the serum potassium concentration and renal potassium excretion were significantly decreased. We conclude that despite marked stimulation of PRA, the plasma aldosterone concentration was further decreased because of a dose-dependent decrease in serum potassium concentration induced by epinephrine. Thus hypokalemia appears to be the predominant regulator of plasma aldosterone during incremental epinephrine infusion.

Effects of sympathetic inhibition on blood pressure and renal responses to central hypervolaemia in normal humans

The purpose of this study was to evaluate the effects of short-term sympathetic inhibition with clonidine on blood pressure and renal responses to central hypervolaemia induced by thermoneutral head-out water immersion. Eleven healthy subjects were randomly studied on two occasions, during a 1 h pre-immersion period, 2 h of water immersion and a 1 h post-immersion period, after either placebo or clonidine treatment. Clonidine caused a significant suppression of plasma adrenaline, plasma noradrenaline, urinary noradrenaline excretion and mean arterial blood pressure. Blood pressure remained constant during water immersion after both placebo and clonidine, compared with the respective pre-immersion control values. The suppression pattern of plasma catecholamines and urinary noradrenaline in response to water immersion during placebo was similar after clonidine treatment. Renal volume excretion was not affected by clonidine. In contrast, clonidine caused a significant attenuation of the immersion-induced stimulation of natriuresis (maximum -33 +/- 12%, P < 0.01, compared with placebo). These data indicate that the renal capacity to excrete sodium is impaired during moderate blood pressure reduction by short-term sympathetic inhibition with clonidine, whereas the regulation of arterial blood pressure in response to central hypervolaemia is maintained.

Platelet rap1B phosphorylation is a sensitive marker for the action of cyclic AMP- and cyclic GMP-increasing platelet inhibitors and vasodilators

Rap1B, a ras-like protein expressed in high concentrations in human platelets, serves as a substrate for protein kinase A (PKA) and, eventually, protein kinase G (PKG). We measured rap1B phosphorylation by autoradiography of 32P-labeled proteins in platelets prelabeled with [32P]-orthophosphate. Platelets coincubated with histamine-stimulated human umbilical vein endothelial cells (EC) showed increased phosphorylation of the 50-Kd vasodilator-stimulated phosphoprotein (VASP) of 2.6 +/- 0.5-fold maximally and of rap1B of 17.5 +/- 7.1-fold maximally (mean +/- SE, n = 4). Incubation of platelets with prostacyclin (PGI2), the PGI2-analogue iloprost (ILO), the nitric oxide (NO) donors SIN-1 or sodium nitroprusside (SNP) showed greater concentration-dependent phosphorylation of rap1B than of VASP. Phosphorylation of rap1B had a slow time course and was irreversible in contrast to that of VASP, which was rapid and reversible. Phosphorylation of rap1B was dependent on an increase of platelet cyclic AMP and/or cyclic GMP. Very small concentrations of ILO (50 pM), PGI2 (1 nM), and SIN-1 (100 nM) increased rap1B phosphorylation. Rap1B phosphorylation could also be detected by Western blot after incubation of platelet-rich plasma (PRP) with ILO or SIN-1. Measurement of platelet rap1B phosphorylation is a novel tool that allows monitoring of the action of labile (PGI2, NO) and more stable (ILO, SIN-1, SNP) platelet inhibitors and vasodilators that increase intracellular cyclic AMP and cyclic GMP. Determination of rap1B phosphorylation by Western blot opens new possibilities of measuring platelet-EC interactions in clinical studies and of monitoring the action of systemically applied PGI2 analogues and nitrovasodilators in pharmacologic studies.

Thrombin receptor-activating peptide sensitizes the human endothelial thrombin receptor

Receptor-operated effects of alpha-thrombin and of the thrombin receptor-activating peptide TRAP14 on cytoplasmic Ca2+ concentration ([Ca2+]i) were examined in fura 2-loaded endothelial cells. Experiments with hirudin showed that alpha-thrombin-induced Ca2+ influx requires the continuous presence of active alpha-thrombin. YFLLRNP, known to antagonize alpha-thrombin- and TRAP7-induced [Ca2+]i transients in platelets, did not antagonize [Ca2+]i transients in response to alpha-thrombin and TRAP14 in human umbilical vein endothelial cells (HUVEC). Repetitive short-term stimulations with alpha-thrombin desensitized [Ca2+]i transients to subsequent stimulations with either alpha-thrombin or TRAP14. In contrast, repeated short-term stimulations with TRAP14 sensitized [Ca2+]i transients to subsequent stimulations with either agonist. Blockade of Ca2+ influx by SKF-96365 abolished the sensitizing effect of TRAP14. The results indicate distinct characteristics of platelet and endothelial thrombin receptors and suggest that alpha-thrombin and TRAP14 activate the receptor differently. It appears that receptor desensitization occurs independently of TRAP14 binding and, hence, tethered ligand binding to and activation of the receptor. Persistent receptor desensitization after alpha-thrombin seems to depend on both alpha-thrombin binding to the hirudin-like receptor domain and the irreversible proteolytic cleavage of the receptor. It does not involve the TRAP14/tethered ligand binding site of the receptor. TRAP14 primes the receptor by a mechanism mediated by Ca2+ influx.

Formation of biologically active autacoids is regulated by calcium influx in endothelial cells

The blocker of receptor-mediated calcium entry SK&F 96365 was used to evaluate the contribution of calcium influx to the formation of biologically active endothelial prostanoids and endothelium-derived relaxing factor (EDRF). SK&F 96365 inhibited histamine-stimulated calcium entry into human umbilical vein endothelial cells but not its discharge from intracellular stores as determined spectrofluorometrically by changes of intracellular calcium concentration in fura-2-loaded cells. Concordantly, SK&F 96365 inhibited histamine-induced endothelial synthesis of 6-keto-prostaglandin F1 alpha and thromboxane B2 in a dose-dependent manner. To assess the functional significance of endothelial formation of prostacyclin and EDRF to platelets, the cAMP- and cGMP-dependent phosphorylation of two platelet proteins, rap1B and a 50-kD vasodilator-stimulated phosphoprotein (VASP), was analyzed in coincubation experiments of endothelial cells with platelets. Autacoids released by histamine-stimulated endothelial cells caused the phosphorylation of rap1B and VASP in platelets, which was only partly inhibited by either indomethacin or NG-monomethyl-L-arginine but was almost completely suppressed by SK&F 96365. The concomitant endothelial release of thromboxane A2 had no effect on protein kinase C- and calcium-dependent phosphorylation of platelet proteins. The results demonstrate that blockade of receptor-mediated calcium entry by SK&F 96365 markedly reduced the release of biologically active prostacyclin and EDRF from endothelial cells. Thus, calcium influx but not calcium release from intracellular stores plays a critical role in the receptor-stimulated formation and liberation of prostacyclin and EDRF in endothelial cells.

Dissociation of renin and aldosterone during low-dose epinephrine infusion

Besides its dose-dependent alpha- and beta-adrenoceptor-mediated vascular action, hormonal effects of epinephrine also involve the activation of renin secretion by direct stimulation of renal beta 1-adrenoceptors. To determine the interrelation between increased plasma renin activity in response to epinephrine and plasma aldosterone concentration and renal excretion of potassium and sodium, 26 normal subjects were subjected to 4 h of an intravenous infusion of low-dose epinephrine (12 ng/kg/min). Epinephrine infusion raised mean plasma epinephrine concentration 2.8-fold above control (P < .001). Plasma renin activity (PRA) increased by 56% (P < .01) during epinephrine infusion, whereas plasma aldosterone concentration remained constant. Infusion of epinephrine also resulted in markedly suppressed urinary potassium excretion (-32%; P < .025), while urinary sodium excretion was not altered. Serum potassium was decreased by 4.1% during epinephrine (P < .025). Systolic blood pressure and heart rate did not change, and diastolic blood pressure was slightly reduced by 5 mm Hg (P < .025). In summary, during low-dose epinephrine infusion PRA is markedly increased while plasma aldosterone remains unchanged. The fall in urinary potassium excretion in the presence of reduced serum potassium concentration is most likely mediated via the beta-adrenoceptor-mediated shift of potassium into cells. This in turn may prevent a concomitant rise of plasma aldosterone, which subsequently contributes to the blunted kaliuresis and unchanged natriuresis found during the epinephrine-induced rise of PRA. In conclusion, the epinephrine-induced fall in serum potassium appears to be the predominant regulator of plasma aldosterone concentration even in the presence of a stimulated PRA.

Thrombin-induced Ca2+ influx and protein tyrosine phosphorylation in endothelial cells is inhibited by herbimycin A

During endothelial cell activation, alpha-thrombin elicits both Ca2+ release from internal stores and influx of external Ca2+ across the plasma membrane. The mechanisms of alpha-thrombin-induced Ca2+ entry into endothelial cells are unclear. Therefore, effects of the specific tyrosine kinase inhibitor herbimycin A on protein tyrosine phosphorylation and on intracellular Ca2+ transients were studied in alpha-thrombin-stimulated human umbilical vein endothelial cells. alpha-Thrombin caused significant tyrosine phosphorylation of mainly two proteins and evoked typical biphasic changes of free cytosolic Ca2+ concentration. We show that 24 h pretreatment with herbimycin A inhibited alpha-thrombin-induced endothelial protein tyrosine phosphorylation. Moreover, herbimycin A significantly attenuated alpha-thrombin-induced Ca2+ influx but not release from internal stores. The data suggest that protein tyrosine phosphorylation by alpha-thrombin is involved in the regulation of alpha-thrombin-induced Ca2+ influx into endothelial cells.

Role of L-type calcium channels on stimulated calcium influx and on proliferative activity of human coronary smooth muscle cells

Dihydropyridine (DHP) calcium channel blockers are widely used in treatment of coronary artery disease. To evaluate the specific role of L-type calcium channels in the antianginal and possibly antiatherosclerotic properties of DHP inhibitors, we examined the effects of a 1,4-DHP agonist and antagonist on angiotensin II (ANG II)- and serum-stimulated calcium influx and proliferation of human coronary smooth muscle cells (cSMC). Fluorometry of fura-2 was used to measure changes in free cytosolic Ca2+ concentration ([Ca2+]i) in cSMC after short- and long-term pretreatment with the calcium agonist Bay K 8644 or the antagonist nitrendipine, respectively. Proliferative activity was quantified during exponential growth in serum-supplemented medium with or without both DHPs. Short- and long-term pretreatment with Bay K 8644 increased basal [Ca2+]i significantly in resting cells and augmented ANG II- and serum-induced sustained [Ca2+]i responses. Concordantly, proliferation rate was increased. In contrast, nitrendipine had no significant effect on basal or stimulated [Ca2+]i after short-term treatment, but decreased [Ca2+]i after 24-h incubation, attenuated the plateau phase of ANG II- and serum-evoked [Ca2+]i transients, and reduced proliferative activity of these cells. The results indicate that 1,4-DHPs modulate ANG II- and serum-induced Ca2+ influx in cSMC. Thus, L-type calcium channels may contribute to [Ca2+]i transients evoked by ANG II and serum. Moreover, the modulating effects of both DHPs on proliferative activity suggest involvement of DHP-sensitive calcium channels. Calcium influx through L-type channels may be one of the mechanisms that determine responsiveness to vasoconstrictors and proliferative activity of human cSMC.

Platelet activating factor enhances receptor-operated Ca(++)-influx and subsequent prostacyclin synthesis in human endothelial cells

Platelet activating factor (PAF) primes vascular actions of mediators such as histamine and stimulates human umbilical vein endothelial cells (HUVECs) to produce prostacyclin (PGI2), which is important for the regulation of vascular tone, perfusion and hemostasis. We demonstrate that pretreatment of HUVECs with PAF enhances thrombin- or histamine-induced rises of cytosolic free Ca(++)-concentration and subsequent Ca(++)-dependent PGI2-synthesis. Inhibition of Ca(++)-influx and PGI2-formation by SKF96365 (blocker of receptor-operated Ca(++)-channels) in PAF-treated cells indicates that the enhancement of PGI2-synthesis by PAF is due to sensitization of Ca(++)-entry. This suggests cooperative effects of PAF on activation processes induced by thrombin or histamine in HUVECs.

Potentiation of clobazam's anticonvulsant activity by etifoxine, a non-benzodiazepine tranquilizer, in mice. Comparison studies with sodium valproate

The interaction of two tranquilizers, the 1,5-benzodiazepine clobazam (CBZ, Frisium) and the non-benzodiazepine etifoxin (Hoe-36,801) hydrochloride (EFX, 6-chloro-2-ethylamino-4-methyl-4-phenyl-4H-3,1-benzoxazine HCl) was investigated for anticonvulsant activity in mice. Corresponding experiments were performed with the antiepileptic drug sodium valproate (VPA). Tonic-clonic (maximal) seizures were induced by maximal electroshock (MES; 12 mA, 200 ms) and clonic (threshold) seizures by pentetrazol (PTZ; 85 mg/kg s.c.). The addition of an anticonvulsant threshold dose of EFX (50 mg/kg p.o.) led to an increase of CBZ's potency against both MES- and PTZ-seizures by 410 or 450%, respectively. Under the same conditions, EFX enhanced the potency of VPA only by 20 or 80% and a threshold dose of VPA (100 mg/kg p.o.) enhanced the potency of CBZ by 110 or 0%, respectively. It is concluded that this potentiation of CBZ's anticonvulsant activity by EFX may be beneficially used in epileptic patients either to increase CBZ's antiepileptic effects or to reduce CBZ's therapeutic doses in order to prevent or delay the development of resistance.

[Immunochemical investigations on the protein of the "pregnancy zone". XI. Serum concentration of the pregnancy-associated alpha2-glycoprotein (Pregnancy Zone protein) in normal pregnancy (author's transl)]

A quantitative study of the pregnancy zone proteins was made in the sera of 383 healthy pregnant women by means of radial immunodiffusion according to Mancini and co-workers. The serum levels related to a pregnancy serum standard were measured from the 6th to 44th week of pregnancy. The serum concentration of the protein showed a considerable individual variation. The mean concentration began to rise in gestational weeks 8 to 24. Until the week 32 a rather stable average level was reached. Before delivery a slight decrease was observed. Women with over term pregnancies showed particular high mean concentrations. The differences of serum levels were statistically significant until the gestational week 14.