Israel Medical Association Journal

For centuries skin pigmentation has played a major societal role. Genetic disorders of skin pigmentation have therefore always evoked the curiosity of both laypersons and physicians. Normal skin pigmentation is a complex process that begins with the synthesis of melanin within the melanocytes, followed by its transfer to neighboring keratinocytes where it is translocated to the upper pole of the nucleus and degraded as the keratinocyte undergoes terminal differentiation. Mutations in various genes involved in melanocyte migration during embryogenesis, melanin synthesis and melanosomal function and transfer have been shown to cause pigmentation disorders. In the present review, we discuss normal skin pigmentation and the genetic underpinning of selected disorders of hypo- and hyperpigmentation.

Sepsis is an infection-induced inflammatory syndrome that results in a complex network of adaptive and maladaptive alterations in homeostatic mechanisms. Severe sepsis, defined as sepsis associated with acute organ failure, is a serious disease with a mortality rate of 30–50%. The coagulation system, through complex interactions, has an important role in the final outcome of the sepsis-induced inflammatory cascade. A fine and delicate balance that normally exists between anticoagulant mechanisms and the procoagulant response is altered in sepsis. Activated protein C, an endogenous vitamin K-dependent anticoagulant, plays a major role in the down-regulation of the procoagulant arm. It also possesses anti-inflammatory properties. Endothelial damage during sepsis impairs the endothelium-dependent activation of protein C, thus shifting the balance towards thrombosis. This shift may contribute to the development of sepsis-related multi-organ failure. Evidence suggesting that activation of the coagulation system may contribute to sepsis-related morbidity and mortality has led to extensive research attempting to correct the hemostatic defects seen in septic patients. Indeed, a recent randomized controlled trial demonstrated a reduction in overall mortality in patients with severe sepsis treated with APC[1]. In this review we discuss the pathogenesis of the coagulopathy of sepsis, as well as the new therapeutic approaches aimed at correcting the defects in the coagulation system.

Knowledge on the pathophysiology of irritable bowel syndrome has evolved, beginning with disturbances in motility to visceral hypersensitivity, and ultimately to alterations in brain-gut bi­directional communication, where neurotransmitters such as serotonin play a key role. Recently, a multicomponent disease model that integrates all these alterations was proposed. This model is divided into physiological, cognitive, emotional and behavioral components that explain the gastrointestinal as well as the constitutional symptoms. In recent years there has been an explosion of research together with new developments in pharmacological treatments for lBS that support each compo­nent of this model. This review presents recent data in favor of these alterations in IBS.