Imaging of Neuromodulation and Surgical Interventions for Epilepsy.

About one-third of epilepsy cases are refractory to medical therapy. During the past decades, the availability of surgical epilepsy interventions has substantially increased as therapeutic options for this group of patients. A wide range of surgical interventions and electrophysiologic neuromodulation techniques are available, including lesional resection, lobar resection, thermoablation, disconnection, multiple subpial transections, vagus nerve stimulation, responsive neurostimulation, and deep brain stimulation. The indications and imaging features of potential complications of the newer surgical interventions may not be widely appreciated, particularly if practitioners are not associated with comprehensive epilepsy centers. In this article, we review a wide range of invasive epilepsy treatment modalities with a particular focus on their postoperative imaging findings and complications. A state-of-the-art treatment algorithm provides context for imaging findings by helping the reader understand how a particular invasive treatment decision is made.

Versatile multi-functionalization of protein nanofibrils for biosensor applications.

Protein nanofibrils offer advantages over other nanostructures due to the ease in their self-assembly and the versatility of surface chemistry available. Yet, an efficient and general methodology for their post-assembly functionalization remains a significant challenge. We introduce a generic approach, based on biotinylation and thiolation, for the multi-functionalization of protein nanofibrils self-assembled from whey proteins. Biochemical characterization shows the effects of the functionalization onto the nanofibrils' surface, giving insights into the changes in surface chemistry of the nanostructures. We show how these methods can be used to decorate whey protein nanofibrils with several components such as fluorescent quantum dots, enzymes, and metal nanoparticles. A multi-functionalization approach is used, as a proof of principle, for the development of a glucose biosensor platform, where the protein nanofibrils act as nanoscaffolds for glucose oxidase. Biotinylation is used for enzyme attachment and thiolation for nanoscaffold anchoring onto a gold electrode surface. Characterization via cyclic voltammetry shows an increase in glucose-oxidase mediated current response due to thiol-metal interactions with the gold electrode. The presented approach for protein nanofibril multi-functionalization is novel and has the potential of being applied to other protein nanostructures with similar surface chemistry.

Structural and dynamic requirements for optimal activity of the essential bacterial enzyme dihydrodipicolinate synthase.

Dihydrodipicolinate synthase (DHDPS) is an essential enzyme involved in the lysine biosynthesis pathway. DHDPS from E. coli is a homotetramer consisting of a 'dimer of dimers', with the catalytic residues found at the tight-dimer interface. Crystallographic and biophysical evidence suggest that the dimers associate to stabilise the active site configuration, and mutation of a central dimer-dimer interface residue destabilises the tetramer, thus increasing the flexibility and reducing catalytic efficiency and substrate specificity. This has led to the hypothesis that the tetramer evolved to optimise the dynamics within the tight-dimer. In order to gain insights into DHDPS flexibility and its relationship to quaternary structure and function, we performed comparative Molecular Dynamics simulation studies of native tetrameric and dimeric forms of DHDPS from E. coli and also the native dimeric form from methicillin-resistant Staphylococcus aureus (MRSA). These reveal a striking contrast between the dynamics of tetrameric and dimeric forms. Whereas the E. coli DHDPS tetramer is relatively rigid, both the E. coli and MRSA DHDPS dimers display high flexibility, resulting in monomer reorientation within the dimer and increased flexibility at the tight-dimer interface. The mutant E. coli DHDPS dimer exhibits disorder within its active site with deformation of critical catalytic residues and removal of key hydrogen bonds that render it inactive, whereas the similarly flexible MRSA DHDPS dimer maintains its catalytic geometry and is thus fully functional. Our data support the hypothesis that in both bacterial species optimal activity is achieved by fine tuning protein dynamics in different ways: E. coli DHDPS buttresses together two dimers, whereas MRSA dampens the motion using an extended tight-dimer interface.

Combination peroxisome proliferator-activated receptor gamma and alpha agonist treatment in Type 2 diabetes prevents the beneficial pioglitazone effect on liver fat content.

AIMS: Peroxisome proliferator-activated receptor (PPAR)-gamma and PPAR-alpha agonists individually reduce intra-organ triglyceride content and improve insulin sensitivity. However, the precise effects of combined PPAR-gamma and PPAR-alpha therapy on intra-organ triglyceride content and insulin sensitivity in subjects with Type 2 diabetes have not yet been determined. METHODS: Diet-controlled Type 2 subjects (n = 9) were studied before and after 16 weeks of combined PPAR-gamma [pioglitazone (PIO), 45 mg daily] and PPAR-alpha [bezafibrate (BEZA), modified release 400 mg daily] agonist therapy. Glucose metabolism and endogenous glucose production were measured following a standard liquid test meal. Liver and muscle triglyceride levels were measured by (1)H magnetic resonance spectroscopy. RESULTS: Combined PIO and BEZA therapy reduced mean fasting (7.5 +/- 0.5 vs. 6.5 +/- 0.2 mmol/l, P = 0.04) and peak postprandial plasma glucose (15.3 +/- 1.1 vs. 11.7 +/- 0.6 mmol/l, P = 0.007). No significant change in hepatic or muscle triglyceride content was observed. Postprandial suppression of endogenous glucose production remained similar on both study days. Both subcutaneous and visceral fat content increased following therapy. CONCLUSIONS: Combined PIO and BEZA therapy in Type 2 diabetes does not decrease intrahepatic triglyceride content or postprandial endogenous glucose production. This study demonstrates an unexpected adverse interaction of PPAR-alpha with PPAR-gamma agonist therapy.

Is it ethical for a general practitioner to claim a conscientious objection when asked to refer for abortion?

Abortion is one of the most divisive topics in healthcare. Proponents and opponents hold strong views. Some health workers who oppose abortion assert a right of conscientious objection to it, a position itself that others find unethical. Even if allowance for objection should be made, it is not clear how far it should extend. Can conscientious objection be given as a reason not to refer when a woman requests her doctor to do so? This paper explores the idea of the general practitioner (GP) who declines to make a direct referral for abortion, asking the woman to see another GP instead. The purpose is to defend the claim that an appeal to conscientious objection in this way can be reasonable and ethical.

Characterisation of dihydrodipicolinate synthase (DHDPS) from Bacillus anthracis.

Bacillus anthracis is a Gram-positive spore-forming bacterium that is the causative agent of anthrax disease. The use of anthrax as a bioweapon has increased pressure for the development of an effective treatment. Dihydrodipicolinate synthase (DHDPS) catalyses the first committed step in the biosynthetic pathway yielding two essential bacterial metabolites, meso-diaminopimelate (DAP) and (S)-lysine. DHDPS is therefore a potential antibiotic target, as microbes require either lysine or DAP as a component of the cell wall. This paper is the first biochemical description of DHDPS from B. anthracis. Enzyme kinetic analyses, isothermal titration calorimetry (ITC), mass spectrometry and differential scanning fluorimetry (DSF) were used to characterise B. anthracis DHDPS and compare it with the well characterised Escherichia coli enzyme. B. anthracis DHDPS exhibited different kinetic behaviour compared with E. coli DHDPS, in particular, substrate inhibition by (S)-aspartate semi-aldehyde was observed for the B. anthracis enzyme (K(si(ASA))=5.4+/-0.5 mM), but not for the E. coli enzyme. As predicted from a comparison of the X-ray crystal structures, the B. anthracis enzyme was not inhibited by lysine. The B. anthracis enzyme was thermally stabilised by the first substrate, pyruvate, to a greater extent than its E. coli counterpart, but has a weaker affinity for pyruvate based on enzyme kinetics and ITC studies. This characterisation will provide useful information for the design of inhibitors as new antibiotics targeting B. anthracis.

Inhibiting protein-protein interactions as an emerging paradigm for drug discovery.

Association of proteins into homo- and hetero-oligomers plays an important role in a plethora of biological phenomena. Inhibition of these interactions is increasingly recognized as a valuable new direction in drug design. In this mini-review we consider inhibition of protein misfolding and aggregation, molecules that disrupt enzyme quaternary structure, and signaling inhibitors, as emerging drugs.

Protein cross-linking in food.

The aims of this paper are (1) to probe the relationship between molecular structure and protein cross-linking ability for a range of small molecules; (2) to establish whether this relationship holds within a food matrix; and (3) to test the impact of Maillard cross-linking on food functionality, particularly texture, in wheat- and soy-based food systems. A variety of molecules were obtained, either commercially or via organic synthesis. Cross-linking ability was tested using our standard model system, employing ribonuclease A and analyzing the results by SDS-PAGE. Molecules of varying reactivity were tested in wheat- and soy-based products, and the changes in functionality were correlated with changes in protein cross-linking. No simple relationship was found between molecular structure and ability to cross-link ribonuclease. Only the most reactive reagents were able to cross-link within the food matrix. Nevertheless, a low degree of cross-linking was shown to have significant consequences on the properties of wheat- and soy-based foods, suggesting that the Maillard reaction may represent a means to control food texture.

Stability of the insecticide cypermethrin during tomato processing and implications for endocrine activity.

The thermal and pH stabilities of cypermethrin during food processing were investigated using tomato as a model food system and high-performance liquid chromatography as the analytical method. Cypermethrin was thermally unstable in aqueous conditions, where the hydrolysis of the pesticide was accelerated by heat. The mean proportion remaining after heating cypermethrin in water for 10 min was 66%, falling to 27% after 1 h. Similarly, thermal processing of canned tomatoes caused cypermethrin to degrade, with remaining levels in the final product ranging from 30 to 60% of the original. Cypermethrin was unstable at extreme pHs, with acid hydrolysis occurring faster than alkaline hydrolysis in phosphate buffers. The acidity of tomato paste (pH 4.3) caused cypermethrin levels to decrease by 30% within 12 days at 5 degrees C. The studies indicate that cypermethrin residues are likely to degrade by hydrolysis during food processing, thus reducing the exposure of consumers to cypermethrin. 3-Phenoxybenzaldehyde, a hydrolysis breakdown product of cypermethrin, was detected in the tomato paste and from the heating of cypermethrin in water at 100 degrees C. There is concern that the risk of breakdown products in terms of endocrine activity is unknown since in vitro studies reported that cypermethrin breakdown products display endocrine activity.

The effect of Saccharomyces cerevisiae on the stability of the herbicide glyphosate during bread leavening.

AIMS: To investigate the ability of baker's yeast (Saccharomyces cerevisiae) to degrade the herbicide glyphosate during the fermentation cycle of the breadmaking process. METHODS AND RESULTS: Aqueous glyphosate was added to bread ingredients and kneaded by commercially available breadmaking equipment into dough cultures. Cultures were incubated in the breadmaker throughout the fermentation cycle. The recovery of glyphosate levels following fermentation was determined, thus allowing an estimation of glyphosate degradation by yeast. CONCLUSIONS: It was shown, for the first time, that S. cerevisiae plays a role in metabolizing glyphosate during the fermentation stages of breadmaking. Approximately 21% was degraded within 1 h. SIGNIFICANCE AND IMPACT OF THE STUDY: As a result of projected increases in the glyphosate use on wheat and the role of bread as a dietary staple, this may contribute to more informed decisions being made relating to the use of glyphosate on glyphosate-resistant wheat, from a public health/regulatory perspective.

Recurrent bacteremia and multifocal lower limb cellulitis due to Helicobacter-like organisms in a patient with X-linked hypogammaglobulinemia.

We describe a 27-year-old man with X-linked (Bruton's) hypogammaglobulinemia who presented during a 10-month period with recurrent fevers and multifocal lower-limb cellulitis associated with bacteremia due to Helicobacter-like organisms ("Flexispira rappini" and Helicobacter canis). Susceptible individuals may acquire infection of this type as a result of exposure to young dogs.

Novel approaches to the analysis of the Maillard reaction of proteins.

The Maillard reaction comprises a complex network of reactions which has proven to be of great importance in both food science and medicine. The majority of methods developed for studying the Maillard reaction in food have focused on model systems containing amino acids and monosaccharides. In this study, a number of electrophoretic techniques, including two-dimensional gel electrophoresis and capillary electrophoresis, are presented. These have been developed specifically for the analysis of the Maillard reaction of food proteins, and are giving important insights into this complex process.

Fibroblasts require protein kinase C activation to respond to hyaluronan with increased locomotion.

Hyaluronan (HA) stimulates the motility of some but not all cell types. Here, we show that HA-promoted random motility of ras-transformed 10T1/2 (C3) fibroblasts requires activation of protein kinase C and is associated with rapid uptake of HA in a CD44 and RHAMM-dependent manner. The addition of HA to parental 10T1/2 fibroblasts (parental cells) does not stimulate random motility, but these cells can be 'primed' to respond to HA by treatment with the phorbol ester, PMA, for 4-6 h. This effect of PMA requires protein synthesis, PKC activity and is associated with enhanced uptake of HA. These results suggest that the ability of cells to respond to HA is regulated by a protein kinase C-dependent process that may promote uptake of HA.

Independence of firing correlates of anatomically proximate hippocampal pyramidal cells.

In neocortex, neighboring neurons frequently exhibit correlated encoding properties. There is conflicting evidence whether a similar phenomenon occurs in hippocampus. To assess this quantitatively, a comparison was made of the spatial and temporal firing correlations within and between local groups of hippocampal cells, spaced 350-1400 microm apart. No evidence of clustering was found in a sample of >3000 neurons. Moreover, cells active in two environments were uniformly interspersed at a scale of <100 microm, as assessed by the activity-induced gene Arc. Independence of encoding characteristics implies uncorrelated inputs, which could enhance the capacity of the hippocampus to store arbitrary associations.

Reactivation of hippocampal ensemble activity patterns in the aging rat.

In young rats, the pattern of neuronal ensemble activity correlations expressed among hippocampal pyramidal cells during behavior persists during subsequent quiet wakefulness and slow-wave sleep, a process that may facilitate the consolidation of episodic memories. The present study explored the hypothesis that age-related changes in this process might contribute to memory impairments observed during normal aging. Neuronal activity was recorded from CA1 pyramidal cells, and in both young and old rats, there was a strong similarity between the resting epoch activity patterns and those from the preceding behavior epoch. This similarity was strongest during sharp-wave events. There were no detectable differences in the reactivation process or the decay rate between the young and old age groups. Thus, age differences in spatial memory do not appear to be explainable by differences in the spontaneous reactivation of familiar patterns within the hippocampus during the immediate postbehavior period.

Effect of age on burst firing characteristics of rat hippocampal pyramidal cells.

During behavior, hippocampal pyramidal cells emit high frequency bursts, modulated by the animal's location and the 7 Hz theta rhythm. During rest, CA1 EEG exhibits large irregular activity (LIA), containing sharp-wave/ripple complexes, during which pyramidal cells exhibit burst discharge. Aging results in altered intracellular calcium homeostasis, increased electrical coupling and reduced cholinergic modulation within CA1, all of which might affect burst discharge characteristics. During LIA, old rats exhibited more short (3-7 ms) inter-spike intervals, with no change in mean firing rate. During behavior induced theta rhythm, however, interval distributions were not affected by age. Thus, different mechanisms must underlie burst discharge in theta and LIA states. Moreover, age related changes in the cholinergic system appear not to play a major role in shaping the temporal discharge characteristics of CA1 pyramidal cells. The mechanism and significance of the higher frequency bursting in old rats during LIA remains to be determined.

Kinetic characterisation of ene-diol-based inhibitors of alpha-amylase.

A kinetic analysis of the inhibition of malt alpha-amylase by compounds based on ascorbic acid has shown the mode of inhibition to be competitive for the parent compound, but more complex for its derivatives. We have further simplified the ascorbic acid ene-diol pharmacophore by demonstrating that dihydroxyfumaric acid is also a good inhibitor of malt alpha-amylase.