The Cutaneous Microcirculation

The cutaneous microcirculation is organized as two horizontal plexuses. One is situated 1–1.5 mm below the skin surface and the other is at the dermal–subcutaneous junction. Ascending arterioles and descending venules are paired as they connect the two plexuses. From the upper layer, arterial capillaries rise to form the dermal papillary loops that represent the nutritive component of the skin circulation. There are sphincter-like smooth muscle cells at the point where the ascending arterioles divide to form the arteriolar component of the upper horizontal plexus. At the dermal–subcutaneous junction, there are collecting veins with two cusped valves that are oriented to prevent the retrograde flow of blood. Laser Doppler flowmetry has demonstrated vasomotion of red cell flux localized to the sites of ascending arterioles. The simultaneous recording by laser Doppler flowmetry of red cell flux and the concentration of moving red blood cells from individual sites allows one to construct topographic maps of these two values. These two maps, based on initial studies using correlative skin biopsies, can define 1 mm3 volumes of skin that are predominantly arteriolar in composition, venular in composition, or essentially devoid of all microvascular elements. The electron and light microscopic features that define the microvascular segments, when coupled with that ability of laser Doppler flowmetry to define the predominant microvascular segments under the probe, allow one to study both the mechanisms of normal physiologic states and the pathogenetic mechanisms underlying pathologic skin disorders in which the microvasculature plays a predominant role

The Response of Psoriatic Epidermis and Microvessels to Treatment with Topical Steroids and Oral Methotrexate

In a previous paper we showed that the microvessels in a psoriatic plaque as studied by electron microscopy returned to normal before the labeling index of the basal cells did during successful therapy with PUVA or the Goeckerman treatment. In this paper we studied the same parameters in 4 additional psoriatic patients: 2 received oral methotrexate and 2 were treated with a topical steroid under plastic wrap occlusion. The labeling index of the basal cells returned to normal in 3 and near normal in 1. The histologic features of the psoriatic epidermis became normal except for mild to moderate acanthosis, but the capillary loops in the dermal papillae retained their venous capillary ultrastructure and showed no signs of reversion to a normal arterial capillary configuration. The lack of response of the dermal capillaries to the topical steroid and oral methotrexate during the initial clinical improvement raises the possibility that the clinical relapses in psoriasis which may promptly follow discontinuation of topical steroid therapy and oral methotrexate may be related to an inability of these drugs to restore the microvasculature to normal in such situations

Nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis, initially called nephrogenic fibrosing dermopathy, has been strongly linked to exposure to gadolinium-based contrast media used in magnetic resonance imaging in patients with renal insufficiency. This review discusses recent advances in our understanding of the pathophysiology and clinical approach to patients with chronic kidney disease who require diagnostic imaging with gadolinium-based contrast media

Small vessel disease in primary familial brain calcification with novel truncating PDGFB variants

Introduction. Primary familial brain calcification (PFBC) is a neurodegenerative disease characterised by bilateral calcification in the brain, especially in the basal ganglia, leading to neurological and neuropsychiatric manifestations. White matter hyperintensities (WMH) have been described in patients with PFBC and pathogenic variants in the gene for platelet-derived growth factor beta polypeptide (PDGFB), suggesting a manifest cerebrovascular process. We present below the cases of two PFBC families with PDGFB variants and stroke or transient ischaemic attack (TIA) episodes. We examine the possible correlation between PFBC and vascular events as stroke/TIA, and evaluate whether signs for vascular disease in this condition are systemic or limited to the cerebral vessels. Material and methods. Two Swedish families with novel truncating PDGFB variants, p.Gln140* and p.Arg191*, are described clinically and radiologically. Subcutaneous capillary vessels in affected and unaffected family members were examined by light and electron microscopy. Results. All mutation carriers showed WMH and bilateral brain calcifications. The clinical presentations differed, with movement disorder symptoms dominating in family A, and psychiatric symptoms in family B. However, affected members of both families had stroke, TIA, and/or asymptomatic intracerebral ischaemic lesions. Only one of the patients had classical vascular risk factors. Skin microvasculature was normal. Conclusions. Patients with these PDGFB variants develop microvascular changes in the brain, but not the skin. PDGFB-related small vessel disease can manifest radiologically as cerebral haemorrhage or ischaemia, and may explain TIA or stroke in patients without other vascular risk factors

Barriers to asymptomatic screening and other STD services for adolescents and young adults: focus group discussions

BACKGROUND: Sexually transmitted diseases (STDs) are a major public health problem among young people and can lead to the spread of HIV. Previous studies have primarily addressed barriers to STD care for symptomatic patients. The purpose of our study was to identify perceptions about existing barriers to and ideal services for STDs, especially asymptomatic screening, among young people in a southeastern community. METHODS: Eight focus group discussions including 53 White, African American, and Latino youth (age 14–24) were conducted. RESULTS: Perceived barriers to care included lack of knowledge of STDs and available services, cost, shame associated with seeking services, long clinic waiting times, discrimination, and urethral specimen collection methods. Perceived features of ideal STD services included locations close to familiar places, extended hours, and urine-based screening. Television was perceived as the most effective route of disseminating STD information. CONCLUSIONS: Further research is warranted to evaluate improving convenience, efficiency, and privacy of existing services; adding urine-based screening and new services closer to neighborhoods; and using mass media to disseminate STD information as strategies to increase STD screening

Magnetic Charge Lattices, Moduli Spaces and Fusion Rules

We analyze the set of magnetic charges carried by smooth BPS monopoles in Yang-Mills-Higgs theory with arbitrary gauge group G spontaneously broken to a subgroup H. The charges are restricted by a generalized Dirac quantization condition and by an inequality due to Murray. Geometrically, the set of allowed charges is a solid cone in the coroot lattice of G, which we call the Murray cone. We argue that magnetic charge sectors correspond to points in the Murray cone divided by the Weyl group of H; hence magnetic charge sectors are labelled by dominant integral weights of the dual group H*. We define generators of the Murray cone modulo Weyl group, and interpret the monopoles in the associated magnetic charge sectors as basic; monopoles in sectors with decomposable charges are interpreted as composite configurations. This interpretation is supported by the dimensionality of the moduli spaces associated to the magnetic charges and by classical fusion properties for smooth monopoles in particular cases. Throughout the paper we compare our findings with corresponding results for singular monopoles recently obtained by Kapustin and Witten.Comment: 53 pages, 6 figure

Urticaria (Book) Robert P.WarioRobert H.ChampionVolume I in the Series, Major Problems in Dermatology, Arthur Rook, M.D., F.R.C.P., Consulting Editor1974W. B. Saunders CompanyPhiladelphia173$13.50

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