Rapid reduction of severe asymptomatic hypertension. A prospective, controlled trial

Rapid reduction of severe asymptomatic hypertension with orally administered antihypertensive medication has become a common emergency department practice. To determine if antihypertensive loading prior to initiation of maintenance therapy improved or hastened blood pressure control, 64 asymptomatic patients with severe hypertension were randomized to treatment with (1) hourly doses of clonidine hydrochloride followed by maintenance therapy (group 1); (2) an initial dose of clonidine followed by hourly placebo and subsequent maintenance therapy (group 2); or (3) maintenance therapy without prior loading (group 3). There was no difference between groups 1 and 2 in the time required to achieve acceptable blood pressure control during loading therapy, nor was there a difference at 24 hours in pressure reduction between groups 1,2, or 3. Further follow-up in 44 of these patients at 1 week demonstrated adequate control of systemic blood pressure in all groups, but no difference between groups. In view of the small but reported risk of antihypertensive loading and the burden and expense of prolonged emergency department therapy, these results suggest that the common practice of acute oral antihypertensive loading to treat severe, asymptomatic hypertension should be reconsidered.     

Use of preformed hydroxylapatite blocks for grafting in genioplasty procedures

Dense hydroxylapatite is a synthetic, biocompatible, immunologically inert material that can establish a chemical union with bone when placed in intimate contact in histologic studies. The following is a preliminary report of the use of preformed dense, non-resorbable hydroxylapatite blocks as a grafting material for use in advancement and vertical lengthening of the bony chin associated with orthognathic surgical procedures. In rare instances where an autogenous bone graft would be required for vertical lengthening without any advancement of bony pogonion, the need is obviated by utilization of the hydroxylapatite solid block.     

Drug design: nitrosoureas

Attempts to develop more effective and less toxic antineoplastic nitrosoureas are summarized. Previous research resulted in the synthesis and extensive preclinical testing of new, short-chain, water-soluble, but lipophilic compounds--1-(2-chloroethyl)-1-nitroso-3-(2-hydroxyethyl)urea (HECNU) and 1-(2-chloroethyl)-1-nitroso-3-(methylene carboxamido)urea. Molecular mechanisms of reactions with biomolecules are discussed with regard to DNA alkylation and cross-linking, carbamoylation of glutathione and glutathione reductase inhibition. Results of a clinical phase-II study show that HECNU, as predicted from preclinical tests, exhibits outstanding activity in brain tumours. Future development concentrates on the use of carrier molecules for nitrosoureas. Results of an extensive structure-activity study with oestradiol-linked analogues show that an oestradiol-17 ester derivative is much more active than other analogues.     

Color‐coded duplex ultrasound for diagnosis of renal artery stenosis and as follow‐up examination after revascularization

Currently, angiography is still considered to be the gold standard for the diagnosis of a renal artery stenosis (RAS). However, angiography is invasive and carries the potential risk of haematoma, pseudoaneurysm, contrast agent induced nephropathy, and athermanous embolization. Color‐coded duplex ultrasound is a noninvasive frequently repeatable bed‐side examination and is currently the only diagnostic method to reliably differentiate between a hemodynamically relevant or irrelevant stenosis using the side‐to‐side difference of the intrarenal resistance index (RI). There is a highly specific correlation between a side difference of the RI of >0.05 and an at least 70% angiographic diameter stenosis. All other duplex parameters like a peak systolic flow velocity >200 cm/sec or a renal aortic flow velocity ratio >3.5 are correlated to a 50 or 60% angiographic diameter stenosis and offer therefore indeed a high sensitivity in terms of detecting a RAS; however, the specificity detecting a hemodynamically relevant RAS is low. Provided that duplex ultrasound is performed by an experienced physician with an adequate machine it should be the preferred imaging method. The present article gives an overview about the literature related to duplex based diagnosis of RAS and as a follow‐up diagnostic procedure following RAS revascularization. © 2008 Wiley‐Liss, Inc.     

Vasodilator agents and supracollicular transection fail to inhibit cortical spreading depression in the cat

It remains an open question as to whether cortical spreading depression (CSD) is the pathophysiological correlate of the neurological symptoms in migraine with aura. In the experimental animal, CSD is an electrophysiological phenomenon mainly mediated via NMDA receptors. However, according to case reports in humans, visual aura in migraine can be alleviated by vasodilator substances, such as amyl nitrite and isoprenaline. There is also circumstantial evidence that brainstem nuclei (dorsal raphe nucleus and locus coeruleus) may play a pivotal role in the initiation of aura. In this study, CSD was elicited in alpha-chloralose anesthetized cats by cortical needle stab injury and monitored by means of laser Doppler flowmetry. Topical application of isoprenaline (0.1-1%) and amyl nitrite (0.05%) onto the exposed cortex had no effect on the elicitation or propagation of CSD. Also, after supracollicular transection, subsequent CSDs showed no differences in the speed of propagation and associated flow changes. We conclude from these data that--given CSD probably exists in humans during migraine--spreading neurological deficits during migraine aura are independent of brainstem influence and have a primarily neuronal rather than vascular mechanism of generation.     

New vectors of Rift Valley fever in West Africa.

After an outbreak of Rift Valley fever in Southern Mauritania in 1987, entomologic studies were conducted in a bordering region in Sénégal from 1991 to 1996 to identify the sylvatic vectors of Rift Valley fever virus. The virus was isolated from the floodwater mosquitoes Aedes vexans and Ae. ochraceus. In 1974 and 1983, the virus had been isolated from Ae. dalzieli. Although these vectors differ from the main vectors in East and South Africa, they use the same type of breeding sites and also feed on cattle and sheep. Although enzootic vectors have now been identified in West Africa, the factors causing outbreaks remain unclear.     

Ankle: surface coil MR imaging at 1.5 T

High-field surface coil magnetic resonance (MR) images were obtained of 12 ankles: two from healthy volunteers, seven from patients, and three from fresh cadavers. The cadaver ankles were sectioned in the coronal, sagittal, and axial planes for direct comparison with the MR images. Plain film confirmation of pathologic conditions was obtained in all patients, and five underwent arthroscopy or surgery, or both. MR imaging provided excellent delineation of ligaments and cartilaginous structures in all cases.