Primary craniosynostosis: imaging features

In 1851, Virchow introduced the term craniosynostosis to describe a variety of abnormalities in calvarial growth. These skull deformities are usually apparent in infancy. When an abnormal calvarial configuration is detected, a radiologic evaluation is necessary to characterize the deformity and to guide the corrective surgical procedure. Affected children are believed to have an improved outcome when diagnosis and surgical intervention occur at an early age. CT with three-dimensional reconstruction optimally evaluates the presence and degree of sutural involvement and assesses associated facial and intracranial abnormalities. This pictorial essay illustrates the imaging findings, nomenclature, and associated abnormalities of the various types of primary craniosynostosis.     

Accuracy of color doppler velocity in the flow field proximal to a regurgitant orifice: implications for color doppler quantitation of valvular incompetence

Color Doppler is routinely used in estimates of valvular regurgitation. Velocity and subsequently flow measurements are made at about 7-10 cm from the ultrasonic transducer. Error in velocity measurement may occur due to spatial broadening of the color Doppler beam in the axial, azimuthal and lateral directions. Error in velocity may also occur due to wall filters since the filtering process is not uniform throughout the velocity range indicated by the color bar. An attempt to estimate this error was made using an in vitro orifice model, a numerical finite element model (FEM), and information from the manufacturer. We found that the acoustic beam spatial expansion, wall filter sensitivity and Nyquist limit (NYL) have to be considered simultaneously to account for errors. The combined spatial expansion and wall filter effect on velocity was estimated as a weighted average over the sample volume. The error distributions are not universal but depend on orifice size and flow. For a 3-mm orifice and 100 cm s NYL the overall effect was overestimation of low velocities and significant underestimation of high velocities due to the high velocity gradients inside the sample volume. For the 5- and the 10-mm orifice the effect was less accentuated. Based on this overall error distribution, a correction was incorporated on color Doppler obtained data. The incorporated correction yielded better agreement with numerical velocity data. This correction is important in the application of the proximal isovelocity surface area (PISA) technique and the evaluation of regurgitant flowrates.     

Dermatology and the Internet--uses for the clinic and research

Improvement brought to iodinated molecules aims to obtain an optimal enhancement effect together with a lower toxicity. However, benign adverse events remain a common risk, and anaphylactoid reactions from the intravascular administration of iodinated contrast media may occur at random and are unpredictable. Although most contrast reactions are mild and self-limited, severe and even life-threatening reactions can occur at any time and for any kind of agent. Physicians must be aware of possible complications related to administration of this kind of agents and must be able to identify patients at risk, to care for prevention and prescribe an appropriate premedication regimen.     

Domestic violence. A clinician''s strategy

Pasteurella haemolytica was isolated from three of 18 grass samples and four of 18 water samples collected from two grazing fields occupied by sheep. This microorganism was also isolated from three of nine straw bedding samples collected from a pen housing ewes affected by mastitis caused by P. haemolytica. The same ewes developed scabbed papilloma-like lesions on the teat and udder skin. These lesions were colonized by P. haemolytica of various serotypes. Colder, wetter weather seems to prolong the survival of P. haemolytica in the environment of sheep. Survival of virulent strains of P. haemolytica in the environment could accumulatively increase the bacterial count, contributing to their transmission from animal to animal. The preference of P. haemolytica for colder, wetter conditions was confirmed in the laboratory where this microorganism survived longer in distilled water, phosphate-buffered saline, Todd-Hewitt broth, and ewe's milk kept at 4 degrees C.     

Isolated leptomeningeal Castleman's disease with viral particles in the follicular dendritic cells

To our knowledge, five cases of Castleman's disease involving only the central nervous system have been reported previously. We report a sixth case, which occurred in a 47-year-old woman with a 3-month history of headaches and a large superior frontal lobe mass on neuroimaging. Excisional biopsy revealed confluent lymphoid nodular areas with multiple well-developed germinal centers surrounded by concentrically layered proliferations of small B lymphocytes typical of Castleman's disease. Ultrastructural study found 100-nm virallike particles within follicular dendritic cells as well as intercellular spaces. These particles were suggestive of a D-type retrovirus. The patient underwent postoperative radiotherapy and was neurologically normal 3 months after surgery.     

A chromosome 4 satellite I DNA isolated from SV40-transformed human cells

Anticancer inhibitors of topoisomerase I (TOP1, EC 5.99.1.2) cause the reversible stabilization of the TOP1-DNA covalent complex (cleavable complex). The cleavable complex can be converted into a double-strand break, the presumed cytotoxic lesion, by active replication forks. Cytotoxicity independent of DNA replication has also been demonstrated, and suggested to have possible clinical significance. To assess the importance of the replication-independent mechanism of camptothecin (CPT) cytotoxicity we have analyzed replication-dependent and replication-independent cytotoxicity following a brief CPT treatment (40 min) of seven human colon tumor cell lines. The cell lines were exposed to CPT in the presence or absence of aphidicolin, an inhibitor of DNA polymerases alpha, delta or epsilon. The seven cell lines responded similarly to CPT: treatments of less than 0.5 microM caused cytotoxicity only when DNA replication was ongoing, as evidenced by a plateau in the cytotoxicity curve corresponding to the S-phase fraction and the prevention of this cytotoxicity by aphidicolin cotreatment; at higher CPT doses, the cytotoxicity exceeded the S-phase fraction and was not prevented by aphidicolin. The CPT sensitivity among the cell lines, measured as the concentration required to inhibit cell growth by 25%, was between 0.17 and 0.43 microM without aphidicolin and 2-10 microM with aphidicolin cotreatment; with aphidicolin in cotreatment, 20-fold greater CPT concentrations were required, on average among the cell lines, to achieve cytotoxicity equivalent to CPT treatment alone. The potential of the lower dose and longer duration treatments of camptothecins used in the clinical setting to produce cytotoxicity independent of DNA replication is discussed.