Respiratory syncytial virus and human metapneumovirus in children with acute respiratory infections in Yemen

A survey of 604 Yemeni children younger than 2 years with acute respiratory infections identified respiratory syncytial virus (RSV) in 244 (40%), human metapneumovirus (HMPV) in 41 (7%) and RSV/HMPV coinfection in 25 (4%) children. RSV infections occurred in younger children and were associated with more severe hypoxia than observed with HMPV. Both viruses are important causes of severe acute respiratory infection in Yemen.     

Mechanisms of classical crystal growth theory explain quartz and silicate dissolution behavior

The central control of mineral weathering rates on biogeochemical systems has motivated studies of dissolution for more than 50 years. A complete physical picture that explains widely observed variations in dissolution behavior is lacking, and some data show apparent serious inconsistencies that cannot be explained by the largely empirical kinetic "laws." Here, we show that mineral dissolution can, in fact, be understood through the same mechanistic theory of nucleation developed for mineral growth. In principle, this theory should describe dissolution but has never been tested. By generalizing nucleation rate equations to include dissolution, we arrive at a model that predicts how quartz dissolution processes change with undersaturation from step retreat, to defect-driven and homogeneous etch pit formation. This finding reveals that the "salt effect," recognized almost 100 years ago, arises from a crossover in dominant nucleation mechanism to greatly increase step density. The theory also explains the dissolution kinetics of major weathering aluminosilicates, kaolinite and K-feldspar. In doing so, it provides a sensible origin of discrepancies reported for the dependence of kaolinite dissolution and growth rates on saturation state by invoking a temperature-activated transition in the nucleation process. Although dissolution by nucleation processes was previously unknown for oxides or silicates, our mechanism-based findings are consistent with recent observations of dissolution (i.e., demineralization) in biological minerals. Nucleation theory may be the missing link to unifying mineral growth and dissolution into a mechanistic and quantitative framework across the continuum of driving force.     

Hypertension: pathophysiology and treatment

Arterial hypertension is a major cause of morbidity and mortalitybecause of its association with coronary heart disease, cerebrovasculardisease and renal disease. The extent of target organ involvement(i.e. heart, brain and kidneys) determines outcome. North Americanstudies have shown that hypertension is a major contributorto 500 000 strokes (250 000 deaths) and 1 000 000 myocardialinfarctions (500 000 deaths) per annum.     

The surgical hypertensive patient

We reviewed the pathophysiology and treatment of hypertensionin a recent edition of this journal (see key references). Inthis article, we discuss the management of the hypertensivepatient presenting for surgery and anaesthesia.     

Striatal contributions to working memory: a functional magnetic resonance imaging study in humans

Although the role of the frontal cortex in executive performance has been widely accepted, issues regarding the contribution of subcortical structures to these functions remain unresolved. In this study, the neural circuitry underlying selective subcomponents of working memory was investigated using event-related functional magnetic resonance imaging (fMRI). Ten healthy volunteers performed a verbal memory task, which allowed different aspects of working memory function such as maintenance, retrieval and manipulation to be tested within the same general paradigm. During performance of this task as a whole, fMRI revealed increases in signal intensity throughout the frontostriatal network. However, when signal intensity during the manipulation of information within working memory was compared to that during periods requiring only simple maintenance and retrieval, significant changes were observed only in the caudate nuclei, bilaterally. These results suggest an essential and specific role for the caudate nucleus in executive function, which may underlie the cognitive disturbances observed in frontostriatal neurodegenerative disorders such as Parkinson's disease.     

Effectiveness of a dynamic breast examination training model to improve clinical breast examination (CBE) skills

Despite the potential utility of clinical breast examination (CBE), doctors' palpation skills are often inadequate and difficult to train. CBE sensitivity ranges from 39-59%, in part because current training does not effectively teach tactile skills. To address CBE training limitations, we developed a breast examination training model with 15 dynamically controlled lumps, set to desired hardness within underlying rib and muscle structures, in a silicone breast. In an experiment of 48 medical students, training with the dynamic model increased lump detection by 1.35 lumps compared to 0.60 lumps for a traditional breast model (P=0.008), reduced false positives by -0.70 lumps compared to +0.42 lumps (P=0.0277), and demonstrated skill transfer with a 1.17 lump detection improvement on the traditional device compared to only a 0.17 lump detection improvement by traditional device trainees on the dynamic device (P<0.001). Findings demonstrate the advantage of the dynamic model over conventional models in training CBE tactile skills.     

Public perceptions of child abuse and neglect in a midwestern urban community

This study found that the majority of urban adults did not believe that any of the characteristics of children posed to them predisposed a child to abuse. In contrast, 40% of respondents claimed child abuse could not occur in a family like the one in which they grew up. The majority perceived only one characteristic, alcohol abuse, as a characteristic of child abusers. Few respondents (10%) believed that child abusers could not be helped, and 25% were not sure. Adults' perceptions of child abuse and abusers varied by sex, age, socioeconomic status, and whether the respondents had children. The data indicate that there are significant deficits in the respondents' knowledge of child abuse and neglect.