[The hereditary vessel disease CADASIL].

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is a hereditary small vessel disease of the brain characterized by progressive white matter lesions, subcortical infarcts, and cognitive decline. This autosomal dominant disorder is caused by mutations in the NOTCH3 gene located on chromosome 19, resulting in the accumulation of granular osmiophilic material within the walls of small arteries and arterioles. Clinically, CADASIL typically manifests in mid-adulthood with recurrent ischemic events, migraine with aura, mood disturbances, and cognitive impairment. Neuroimaging plays a crucial role in the diagnosis of CADASIL, with characteristic findings including white matter hyperintensities particularly in the anterior temporal lobe and external capsule.

[A 50 year old man with progressive weakness in lower limbs].

Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare neurological disorder caused by autoimmune antibodies attacking the presynaptic neuromuscular junction, in some cases caused by underlying cancer. The main clinical finding is fluctuating weakness of the extremities and a triad of symtoms can help physicians suspect the disease. A key to the diagnosis are the electrophysiological abnormalities seen in this group of diseases. Treatment with symtomatic and/or immunosuppressive therapy is important as well as a workup for possible malignancy. This article identifies the clinical features, diagnosis and treatment of this uncommon disease.

[Dawn of a new Day - A brief History of Stroke Treatment in Iceland].

Here we will briefly review the main influential factors and milestones in the history of stroke care in Iceland. Over the last few decades the treatment of ischemic stroke has revolutionized in many ways and so has the general mindset of those providing it. This review article is partly based upon interviews with Icelandic doctors that partook in the development. Looking back at this history it is clear that, in many ways, the medical care in Iceland was at the forefront in implementing those emerging new treatments in stroke care. This is mainly on account of ambitious and hard working individuals that were not easily dissuaded but firmly believed in the possibility of better outcomes for their stroke patients.

[Sudden loss of consciousness due to artery of Percheron infarction].

Acute cerebral infarction due to occlusion of the artery of Percheron (AOP) is rare and poses a diagnostic challenge due to unspecific clinical symptoms. A prompt diagnosis and treatment is vital due to a potentially very serious outcome. Here we represent a healthy young woman who developed sudden headache and loss of consciousness. At admission she was unconscious with GCS of 4, pupils were unevenly dilated and poorly reactive and the plantar reflex was upward bilaterally. She had seizure like movements in all limbs. CT of brain and CT angiography were normal but acute MRI showed bilateral paramedian thalamic diffusion restriction. The patient was treated with i.v. thrombolysis (tPA) 70 minutes after hospital arrival and recovered fully.

eNOS activation mediated by AMPK after stimulation of endothelial cells with histamine or thrombin is dependent on LKB1.

Reports on the role of AMP-activated protein kinase (AMPK) in thrombin-mediated activation of endothelial nitric-oxide synthase (eNOS) in endothelial cells have been conflicting. Previously, we have shown that under culture conditions that allow reduction of ATP-levels after stimulation, activation of AMPK contributes to eNOS phosphorylation and activation in endothelial cells after treatment with thrombin. In this paper we examined the signaling pathways mediating phosphorylation and activation of eNOS after stimulation of cultured human umbilical vein endothelial cells (HUVEC) with histamine and the role of LKB1-AMPK in the signaling. In Morgan's medium 199 intracellular ATP was lowered by treatment with histamine or the ionophore A23187 while in medium RMPI 1640 ATP was unchanged after identical treatment. In medium 199 inhibition of Ca(+2)/CaM kinase kinase (CaMKK) by STO-609 only partially inhibited AMPK phosphorylation but after gene silencing of LKB1 with siRNA there was a total inhibition of AMPK phosphorylation by STO-609 after treatment with either histamine or thrombin, demonstrating phosphorylation of AMPK by both upstream kinases, LKB1 and CaMKK. Downregulation of AMPK with siRNA partially inhibited eNOS phosphorylation caused by histamine in cells maintained in medium 199. Downregulation of LKB1 by siRNA inhibited both phosphorylation and activity of eNOS and addition of the AMPK inhibitor Compound C had no further effect on eNOS phosphorylation. When experiments were carried out in medium 1640, STO-609 totally prevented the phosphorylation of AMPK without affecting eNOS phosphorylation. AMPKα2 downregulation resulted in a loss of the integrity of the endothelial monolayer and increased expression of GRP78, indicative of endoplasmic reticular (ER) stress. Downregulation of AMPKα1 had no such effect. The results show that culture conditions affect endothelial signal transduction pathways after histamine stimulation. Under conditions where intracellular ATP is lowered by histamine, AMPK is activated by both LKB1 and CaMKK and, in turn, mediates eNOS phosphorylation in an LKB1 dependent manner. Both AMPKα1 and -α2 are involved in the signaling. Under conditions where intracellular ATP is unchanged after histamine treatment, CaMKK alone activates AMPK and eNOS is phosphorylated and activated independent of AMPK.

Mechanism of thrombin mediated eNOS phosphorylation in endothelial cells is dependent on ATP levels after stimulation.

Conflicting results have been reported concerning the role of AMP-activated protein kinase (AMPK) in mediating thrombin stimulation of endothelial NO-synthase (eNOS). We examined the involvement of two upstream kinases in AMPK activation in cultured human umbilical endothelial cells, LKB1 stimulated by a rise in intracellular AMP/ATP ratio, and Ca(+2)/CaM kinase kinase (CaMKK) responding to elevation of intracellular Ca(+2). We also studied the effects of AMPK activation on the downstream target eNOS. In culture medium 1640 the level of intracellular ATP was unchanged after thrombin stimulation and the CaMKK inhibitor STO-609 totally inhibited phosphorylation of AMPK and acetyl coenzyme A carboxylase (ACC) but not eNOS. In Morgan's medium 199 thrombin caused a significant lowering of intracellular ATP and STO-609 only partially inhibited the phosphorylation of AMPK, ACC and eNOS. Inhibition of AMPK by Compound C or AMPK downregulation using siRNA partially inhibited the phosphorylation of eNOS in medium 199 but not in 1640, underscoring a clear difference in the pathways mediating thrombin-stimulated eNOS phosphorylation in different culture media. Thus, conditions subjecting endothelial cells to a fall in ATP after thrombin stimulation facilitate activation of pathways partly dependent on AMPK causing downstream phosphorylation of eNOS. In contrast, under culture conditions that do not facilitate a fall in ATP after stimulation, AMPK activation is exclusively mediated by CaMKK and does not contribute to the phosphorylation of eNOS.

Thrombin or Ca(++)-ionophore-mediated fall in endothelial ATP levels independent of poly(ADP-Ribose) polymerase activity and NAD levels--comparison with the effects of hydrogen peroxide.

To test the hypothesis that a fall in cellular ATP following stimulation of endothelial cells with thrombin is secondary to a decrease in NAD levels caused by poly(ADP-Ribose)polymerase (PARP), we measured the levels of NAD and ATP in endothelial cells after treatment with thrombin, the Ca(++)-ionophore A23187, or hydrogen peroxide (H2O2), and compared the effects of inhibitors of PARP, NAD synthesis, and ADP-ribose breakdown on these responses. Neither thrombin nor A23187 caused a reduction in endothelial NAD levels and A23187 affected ATP levels independently of NAD levels or PARP activity. H2O2 induced lowering of NAD caused modest lowering of ATP but marked additional ATP-lowering, independent of PARP and NAD, was also demonstrated. We conclude that in endothelial cells ATP levels are largely independent of NAD and PARP, which do not play a role in thrombin or Ca(++)-ionophore-mediated lowering of ATP. H2O2 caused ATP lowering through a similar mechanism as thrombin and A23187 but, additionally, caused a further ATP lowering through its intense stimulation of PARP and marked lowering of NAD.

Thrombin and histamine stimulate endothelial nitric-oxide synthase phosphorylation at Ser1177 via an AMPK mediated pathway independent of PI3K-Akt.

Histamine and thrombin cause phosphorylation and activation of endothelial NO-synthase (eNOS) on Ser1177. We tested the role of various protein kinases in mediating this effect in human umbilical vein endothelial cells. Inhibition of the Ca2+/calmodulin-dependent protein kinase II or phosphoinositide 3-kinase (PI3K) had no effect. H89, an inhibitor of both protein kinase A (PKA) and 5'-AMP-activated protein kinase (AMPK), strongly inhibited phosphorylation and activity of eNOS. Conversely, the PKA inhibitor Rp-adenosine 3 '5'-cyclic monophosphate (cAMPS) had no effect and eNOS was not phosphorylated by treatments that affect cAMP levels. Thrombin and histamine caused phosphorylation of AMPK on Thr172 as well as on its downstream target acetyl-CoA carboxylase. Activation of AMPK using AICAR or CCCP also resulted in eNOS phosphorylation. We conclude that histamine and thrombin cause eNOS phosphorylation in an AMPK mediated manner, independent of P13K-Akt.

Inhibition of Akt phosphorylation by thrombin, histamine and lysophosphatidylcholine in endothelial cells. Differential role of protein kinase C.

The protein kinase Akt is involved in embryonic vascular development and neoangiogenesis as well as in several endothelial cell functions, including activation of endothelial NO-synthase (eNOS) and promotion of endothelial cell survival. We have examined the effects of G-protein activators thrombin and histamine as well as lysophosphatidylcholine (LPC) on Akt phosphorylation in cultured human umbilical vein endothelial cells (HUVEC). Akt phosphorylation was analyzed with the phosphospecific Akt (Ser473) antibody by Western blotting. While epidermal growth factor (EGF) was a potent stimulator of Akt phosphorylation histamine, thrombin and LPC blocked its activation when used in cotreatment with EGF. Following inhibition or downregulation of protein kinase C (PKC), the inhibitory effect of both histamine and thrombin on the endothelial response to EGF was prevented. Furthermore, stimulation of PKC, using short-term 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment, markedly inhibited the stimulatory effects of EGF on Akt phosphorylation. Rottlerin, an inhibitor of the PKCdelta, but not Gö6976, which is an inhibitor of alpha, beta, gamma and isoforms, reversed the inhibitory effects of histamine. Conversely, inhibition or downregulation of PKC did not prevent the inhibitory effect of LPC. Akt phosphorylation was also increased by sphingosine 1-phosphate (S1P) treatment and this activity was influenced by the various cotreatments in the same way as the activation by EGF. Overall, this study demonstrated that the G-protein activators thrombin and histamine inhibited both EGF- and S1P-mediated Akt phosphorylation in HUVEC by activation of PKCdelta, while the inhibitory effects of LPC were independent of PKCdelta.