Functional outcome assessment of adults with right hemisphere brain damage

This article addresses functional outcome assessment of adults with cognitive-communicative disorders due to relatively focal right hemisphere brain damage (RBD). Our discussion observes the World Health Organization's orientation on the multidimensional consequences of health conditions. The WHO framework distinguishes specific deficits (impairments) from their functional consequences: disabilities, or restrictions in daily life activities and handicaps, or broader changes in life role participation. Although there is little evidence about the functional aftermath of RBD, especially in relation to cognitive-communicative disorders, we summarize the data and observations that are available and hypothesize about relationships among outcomes at different levels. We also describe some tools and procedures that may be useful for measuring functional outcomes after RBD, along with relevant caveats, and end with a discussion of research needs and future directions, emphasizing gaps that span the range from basic investigation to treatment research to instrument and procedure development.     

Wavelet image extension for analysis and classification of infarcted myocardial tissue

Some computer applications for tissue characterization in medicine and biology, such as analysis of the myocardium or cancer recognition, operate with tissue samples taken from very small areas of interest. In order to perform texture characterization in such an application, only a few texture operators can be employed: the operators should be insensitive to noise and image distortion and yet be reliable in order to estimate texture quality from the small number of image points available. In order to describe the quality of infarcted myocardial tissue, we propose a new wavelet-based approach for analysis and classification of texture samples with small dimensions. The main idea of this method is to decompose the given image with a filter bank derived from an orthonormal wavelet basis and to form an image approximation with higher resolution. Texture energy measures calculated at each output of the filter bank as well as energies of synthesized images are used as texture features in a classification procedure. We propose an unsupervised classification technique based on a modified statistical t-test. The method is tested with clinical data, and the classification results obtained are very promising. The performance of the new method is compared with the performance of several other transform-based methods. The new algorithm has advantages in classification of small and noisy input samples, and it represents a step toward structural analysis of weak textures.     

Cytochrome P450-mediated metabolism of the HIV-1 protease inhibitor ritonavir (ABT-538) in human liver microsomes

The HIV-1 protease inhibitor ritonavir (ABT-538) undergoes cytochrome P450-mediated biotransformation in human liver microsomes to three major metabolites, Ml, M2 and M11, with wide interindividual variation in the rates of metabolite formation. The structures of these metabolites were determined with the use of electrospray ionization mass spectrometry. Chemical inhibition, metabolic correlation, immunoinhibition and metabolism by microsomes derived from specific CYP cDNA-transfected B-lymphoblastoid cell lines indicated that the CYP3A subfamily of enzymes was the major contributor to the formation of M1 and M11, whereas both CYP3A and CYP2D6 contributed to the formation of M2. None of the typical CYP3A substrates/inhibitors (e.g., ketoconazole, troleandomycin) were able to completely inhibit ritonavir metabolism, even at high concentrations. Ritonavir was found to be a potent inhibitor of CYP3A-mediated biotransformations (nifedipine oxidation, IC50) = 0.07 microM; 17alpha-ethynylestradiol 2-hydroxylation, IC50 = 2 microM; terfenadine hydroxylation, IC50 = 0.14 microM). Ritonavir was also found to be an inhibitor of the reactions mediated by CYP2D6 (IC50 = 2.5 microM) and CYP2C9/10 (IC50 = 8.0 microM). The results of this study indicate the potential for in vivo inhibition of the metabolism by ritonavir of drugs that are CYP3A, CYP2D6 and, to a lesser extent, CYP2C9/10 substrates.     

New multimeric magnetic resonance imaging agents

RATIONALE AND OBJECTIVES: The authors investigated the effect of multimerization on the relaxivity of macrocyclic gadolinium (Gd) chelates. The objective was to develop more sensitive magnetic resonance imaging (MRI) contrast agents to study biochemical processes. METHODS: Covalently linked nonionic, macrocyclic, multimeric lanthanide chelates that belong to the classes of dimers, trimers, tetramers, hexamer, and octamer, in the molecular weight range approximately 1 to 5 KDa, were synthesized. The chemical linkage was based on either the amide bond or the 2-hydroxypropylidene bond. Relaxivity values, 20r1, on Gd3+ chelates and hydration numbers, Q, on Tb3+ chelates were determined. RESULTS: Relaxivity values increased with molecular weight and Q values were not affected, the increase in r1 in attributable to the expected increase in the overall rotational correlation time, tau r with an increase in molecular weight. The rigidity of the linkers, which is expected to affect the intrachelate rotational correlation time tau r* that makes a contribution to the overall correlation time, tau r, exerted a noticeable effect. The hydroxyl-based chelates generally had lower r1 values than the amide-based chelates. This is rationalized as arising from the longer and thereby rate-limiting effect of the tau m value for the hydroxyl chelates compared with that reported of the amide-based chelates. This rate limiting effect of tau m becomes a dominant factor controlling attainable enhanced relaxivity when multimers based on traditional chelate designs are used for MRI applications. CONCLUSIONS: Approaches aimed at enhancing relaxivity by modulating the water relaxation time, tau m, will be important for the future development of functional MRI contrast agents for the imaging of biochemical processes.     

Serine protease of hepatitis C virus expressed in insect cells as the NS3/4A complex

Hepatitis C virus (HCV) protease NS3 and its protein activator NS4A participate in the processing of the viral polyprotein into its constituent nonstructural proteins. The NS3/4A complex is thus an attractive target for antiviral therapy against HCV. We expressed the full-length NS3 and NS4A in insect cells as a soluble fusion protein with an N-terminal polyhistidine tag and purified the two proteins to homogeneity. Cleavage at the junction between HisNS3 and NS4A occurs during expression, producing a noncovalent complex between HisNS3 and NS4A with a subnanomolar dissociation constant. We purified the HisNS3/4A complex by detergent extraction of cell lysate and by metal chelate chromatography. We removed the His tag by thrombin cleavage and then further purified the complex by gel filtration. The purified NS3/4A complex is active in a protease assay using a synthetic peptide substrate derived from the NS5A-NS5B junction, with kcat/K(m) of 3700 (+/- 600) M-1 s-1, an order of magnitude above those previously reported for NS3 expressed by other strategies. This high protease activity implies that the full-length sequences of NS3 and NS4A are required for optimal activity of the NS3 protease domain. We examined the dependence of the NS3/4A protease activity on buffer conditions, temperature, and the presence of detergents. We find that, under most conditions, NS3 protease activity is dependent on the aggregation state of the NS3/4A complex. The monodisperse, soluble form of the NS3/4A complex is associated with the highest protease activity.     

Effects of dopaminergic drugs on locomotor activity in teleost fish of the genus Oreochromis (Cichlidae): involvement of the telencephalon

Airpuffs are often used as blink reflex eliciting stimuli, but the airpuff makes an abrupt noise when it leaves the tube. The present study investigated the effects of the tactile and acoustic components of airpuffs on the blink reflex in 18 human subjects. Subjects received airpuffs to the temple at 10.3, 20.7 and 31.0 kPa in a within-subjects design. The airpuff-associated noise was attenuated (Airpuff + Attenuated noise) or airpuffs were presented without noise-attenuation (Airpuff+ Unattenuated noise) in two conditions. In the third condition, the airpuff was directed away from the temple to eliminate the tactile component of the airpuff (Noise alone). Reflexes were larger, more probable and faster to the Airpuff+ Unattenuated noise compared to the Airpuff+ Attenuated noise. This indicates that there is an excitatory influence from the acoustic component of the airpuff. The findings suggest that researchers should reduce the acoustic component of airpuffs in studies that use airpuffs as reflex eliciting stimuli.     

Agonist-induced endocytosis and recycling of the gonadotropin-releasing hormone receptor: effect of beta-arrestin on internalization kinetics

This study examined the dynamics of endocytotic and recycling events associated with the GnRH receptor, a unique G protein-coupled receptor (GPCR) without the intracellular carboxyl-terminal tail, after agonist stimulation, and investigated the role of beta-arrestin in this process. Subcellular location of fluorescently labeled epitope-tagged GnRH receptors stably expressed in HEK 293 cells was monitored by confocal microscopy, and the receptor/ligand internalization process was quantified using radioligand binding and ELISA. Agonist stimulation resulted in reversible receptor redistribution from the plasma membrane into the cytoplasmic compartment, and colocalization of internalized GnRH receptors with transferrin receptors was observed. Internalization experiments for the GnRH receptor and another GPCR possessing a carboxy-terminal tail, the TRH receptor, showed that the rate of internalization for the GnRH receptor was much slower than for the TRH receptor when expressed in both HEK 293 and COS-7 cells. TRH receptor internalization could be substantially increased by coexpression with beta-arrestin in COS-7 cells, while GnRH receptor internalization was not affected by coexpression with beta-arrestin in either cell type. Coexpression of the GnRH receptor with the dominant negative beta-arrestin (319-418) mutant did not affect its ability to internalize, and activated GnRH receptors did not induce time-dependent redistribution of beta-arrestin/green fluorescent protein to the plasma membrane. However, the beta-arrestin mutant impaired the internalization of the TRH receptor, and activated TRH receptors induced the beta-arrestin/green fluorescent protein translocation. This study demonstrates that, despite having no intracellular carboxy-terminal tail, the GnRH receptor undergoes agonist-stimulated internalization displaying distinctive characteristics described for other GPCRs that internalize via a clathrin-dependent mechanism and recycle through an acidified endosomal compartment. However, our data indicate that the GnRH receptor may utilize a beta-arrestin-independent endocytotic pathway.     

Pediatric penetrating thoracic trauma: a five-year experience

Penetrating thoracic trauma is managed nonoperatively in 85% of adult patients. We hypothesized that similar trauma in children would lead to proportionately more vital tissue damage and a higher rate of operative intervention. The pediatric penetrating thoracic trauma experience of a level one trauma center was analyzed over a five-year period. Data reviewed included circumstances of injury, Pediatric Trauma Score (PTS), interventions performed, and outcome. Of 61 children with thoracic trauma, 13 had penetrating injuries. Of these 13, seven were unintentional (five from firearms); the rest were caused by assaults. Seven patients (54%) underwent thoracotomy or laparotomy. All five patients with a PTS < 8 underwent surgical intervention, whereas only two of the eight patients with a PTS > or = 8 needed surgery (P < 0.05). There was one death. We reached the following conclusions: 1) Children with penetrating thoracic trauma are more likely to require surgical intervention than adults. 2) Penetrating thoracic trauma in children should elicit a thorough search for operative lesions. 3) About half these injuries are unintentional, and thus potentially preventable.     

A UHF Probe Reflectometer

A brief survey is presented on existing methods of measuring UHF circuit parameters. The structure is given for a new probe reflectometer, which has a simple design and good characteristics. The latter have been improved by altering the distance between the probes and using probes of different types. The working bandwidth is not less than two octaves.