Three young patients with unusual causes of stroke

Protein C Deficiency as a Risk Factor for Stroke in Young Adults: A Review

Protein C (PC) is a 62-kD vitamin K dependent glycoprotein produced by the liver as a zymogen and is activated by binding to the thrombin-thrombomodulin complex, with protein S (PS) acting as a cofactor. Among its various functions, PC acts as a naturally occurring anticoagulant and its deficiency, either homozygous or heterozygous, predisposes the individual to a state of thrombosis, particularly venous thromboembolism, and mainfests as myocardial infarction (MI), deep venous thrombosis, pulmonary embolism, or stroke. This review discusses the pathophysiology of the anticoagulatory effect of PC, mode of inheritance of its deficiency, the arterial and venous involvement in patients with stroke, and its risk factors. A detailed analysis of published case reports on PC deficiency as a causative agent of stroke in young adults has also been included along with the management of such patients.

The comparative biochemistry of viruses and humans: an evolutionary path towards autoimmunity

Analyses of the peptide sharing between five common human viruses (Borna disease virus, influenza A virus, measles virus, mumps virus and rubella virus) and the human proteome highlight a massive viral vs. human peptide overlap that is mathematically unexpected. Evolutionarily, the data underscore a strict relationship between viruses and the origin of eukaryotic cells. Indeed, according to the viral eukaryogenesis hypothesis and in light of the endosymbiotic theory, the first eukaryotic cell (our lineage) originated as a consortium consisting of an archaeal ancestor of the eukaryotic cytoplasm, a bacterial ancestor of the mitochondria and a viral ancestor of the nucleus. From a pathologic point of view, the peptide sequence similarity between viruses and humans may provide a molecular platform for autoimmune crossreactions during immune responses following viral infections/immunizations.

Cerebral Ischemic Infarction in Paroxysmal Nocturnal Hemoglobinuria

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder, leading to a deficient biosynthesis of surface proteins in hematopoetic cells. Clinical symptoms consist of various combinations of intravascular hemolysis, bone marrow failure and mainly venous thrombotic events. Arterial thrombosis has been described only in a few cases.

METHODS

We report two patients with fatal ischemic strokes in PNH caused by arterial occlusion. In addition we also reviewed 7 previously reported cases in the literature and obtained follow-up information on 4 of the 5 survivors.

RESULTS

Both patients from our clinic had experienced hemoglobinuria and cytopenia prior to the vascular events but in one case diagnosis of PNH was only established after stroke onset. The causal role of PNH was supported by the absence of other vascular risk factors and by simultaneous symptoms of hemolysis and cytopenia. The diagnosis of PNH was confirmed by a positive result in flow cytometry. Despite extended therapeutic interventions, including antithrombotic treatment (with heparin or tirofiban) and decompressive hemicraniectomy both patients developed further thrombotic complications. The two patients died during their hospital stay from vascular or infectious complications. A review of all 9 published cases revealed that four patients died within a few weeks after the initial thrombotic event. No difference in treatment between patients with good or bad outcome was seen.

CONCLUSIONS

PNH is a rare cause of arterial stroke but it should be considered in young stroke patients with abnormal blood findings. As yet, there is no effective antithrombotic treatment.