A case of verrucous perforating collagenoma in a toddler

Verrucous perforating collagenoma is an extremely rare variant of acquired perforating dermatosis that has been seldom described in literature. We present the case of an 18‐month‐old boy who presented with an erythematous plaque with a central keratotic plug on the leg. Histopathology revealed transepidermal elimination of collagen, consistent with a diagnosis of verrucous perforating collagenoma.     

Neurological and humoral control of blood pressure

There is a relationship between arterial blood pressure, cardiac output and vascular resistance described mathematically, that helps us to understand short-term control of blood pressure in terms of a hydraulic system. Arterial baroreceptors are specialized sensors which mediate a rapid response to sudden changes in pressure through interaction with the autonomic nervous system. This in turn influences heart rate, inotropic state and vascular tone, altering distribution of blood between arterial and venous systems, thus compensating for acute changes in total blood volume. Total blood volume is controlled predominantly by the kidney, with the renin–angiotensin–aldosterone system acting as both the ‘sensor’ of blood pressure/volume (via renin release in the juxtaglomerular apparatus) and the ‘effector’ of blood pressure/volume (via aldosterone secretion by the adrenal cortex). Overall control is shared; the baroreceptors being responsible for mediating short-term changes, and renal mechanisms determining the long-term control of blood pressure. These systems have to be adaptable in order to deal with physiological variation in the delivery of blood to tissues from rest to exercise, and with the large shifts in blood volume seen in acute haemorrhage. Pathophysiological changes in these systems lead to maladaptive responses, with systemic hypertension the most commonly seen.     

Idiopathic toxic epidermal necrolysis in an adolescent

A 10‐year‐old girl, suspected 2 days prior to have streptococcal pharyngitis, presented with diffuse erythema, tense bullae, Nikolsky‐positive desquamation, as well as ulcerations of her oral and genital mucosa. She denied recent travel, sick contacts, or preceding and concurrent use of medications, including over‐the‐counter and herbal supplements. A comprehensive viral polymerase chain reaction (PCR) panel, Mycoplasma pneumoniae PCR and IgM, streptococcal molecular antigen test, urine culture, blood culture, and rheumatologic serologies were negative. Based on the patient's clinical presentation and biopsy results, she was diagnosed with idiopathic toxic epidermal necrolysis.     

Notch in memories: Points to remember

Memory is a temporally evolving molecular and structural process, which involves changes from local synapses to complex neural networks. There is increasing evidence for an involvement of developmental pathways in regulating synaptic communication in the adult nervous system. Notch signaling has been implicated in memory formation in a variety of species. Nevertheless, the mechanism of Notch underlying memory consolidation remains poorly understood. In this commentary, besides offering an overview of the advances in the field of Notch in memory, we highlight some of the weaknesses of the studies and attempt to cast light on the apparent discrepancies on the role of Notch in memory. We believe that future studies, employing high‐throughput technologies and targeted Notch loss and gain of function animal models, will reveal the mechanisms of Notch dependent plasticity and resolve whether this signaling pathway is implicated in the cognitive deficit associated with dementia. © 2015 Wiley Periodicals, Inc.