A comparative study of a theoretical neural net model with MEG data from epileptic patients and normal individuals

OBJECTIVE: The aim of this study was to compare a theoretical neural net model with MEG data from epileptic patients and normal individuals. METHODS: Our experimental study population included 10 epilepsy sufferers and 10 healthy subjects. The recordings were obtained with a one-channel biomagnetometer SQUID in a magnetically shielded room. RESULTS: Using the method of x(2)-fitting it was found that the MEG amplitudes in epileptic patients and normal subjects had Poisson and Gauss distributions respectively. The Poisson connectivity derived from the theoretical neural model represents the state of epilepsy, whereas the Gauss connectivity represents normal behavior. The MEG data obtained from epileptic areas had higher amplitudes than the MEG from normal regions and were comparable with the theoretical magnetic fields from Poisson and Gauss distributions. Furthermore, the magnetic field derived from the theoretical model had amplitudes in the same order as the recorded MEG from the 20 participants. CONCLUSION: The approximation of the theoretical neural net model with real MEG data provides information about the structure of the brain function in epileptic and normal states encouraging further studies to be conducted

Adenoma Formation following Limited Ablation of p120-Catenin in the Mouse Intestine

p120 loss destabilizes E-cadherin and could therefore result in tumor and/or metastasis-promoting activities similar to those caused by E-cadherin downregulation. Previously, we reported that p120 is essential in the intestine for barrier function, epithelial homeostasis and survival. Conditional p120 ablation in the mouse intestine induced severe inflammatory bowel disease, but long-term cancer-related studies were impossible because none of the animals survived longer than 21 days. Here, we used a tamoxifen-inducible mouse model (Vil-Cre-ERT2;p120fl/fl) to limit the extent of p120 ablation and thereby enable long-term studies. Reducing p120 KO to ∼10% of the intestinal epithelium produced long-lived animals outwardly indistinguishable from controls. Effects of prolonged p120 absence were then evaluated at intervals spanning 2 to 18 months. At all time points, immunostaining revealed microdomains of p120-null epithelium interspersed with normal epithelium. Thus, stochastic p120 ablation is compatible with crypt progenitor cell function and permitted lifelong renewal of the p120-null cells. Consistent with previous observations, a barrier defect and frequent infiltration of neutrophils was observed, suggesting that focal p120 loss generates a microenvironment disposed to chronic inflammation. We report that 45% of these animals developed tumors within 18 months of tamoxifen induction. Interestingly, β-catenin was upregulated in the majority, but none of the tumors were p120 null. Although further work is required to directly establish mechanism, we conclude that limited p120 ablation can promote tumorigenesis by an indirect non-cell autonomous mechanism. Given that byproducts of inflammation are known to be highly mutagenic, we suggest that tumorigenesis in this model is ultimately driven by the lifelong inability to heal chronic wounds and the substantially increased rates of stochastic gene mutation in tissue microenvironments subjected to chronic inflammation. Indeed, although technical issues precluded direct identification of mutations, β-catenin upregulation in human colon cancer almost invariably reflects mutations in APC and/or β-catenin

Alfven: magnetosphere-ionosphere connection explorers

The aurorae are dynamic, luminous displays that grace the night skies of Earth’s high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth’s atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The “ideal magnetohydrodynamics” description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfvén concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planet

Thermodynamic effects on internal relaxation in diblock copolymers

The dynamics of order parameter fluctuations has been investigated near the maximum of the static structure factor for semidilute solutions in a neutral good solvent of a very high molecular weight diblock copolymer. The effect of the proximity to the disorder-to-order transition (ODT) was evident both in the static light scattering intensity and in the internal relaxation by increasing the copolymer concentration up to phi(ODT). All extra relaxation was also observed which can be attributed to curvilinear Rouse motion of the blocks between entanglements inside their tubes

Resistance to activated protein C and FV Leiden mutation in patients with a history of acute myocardial infarction or primary hypertension

This study was designed to investigate both resistance to activated protein C (APC-R) and the factor FV Q506 mutation incidence in patients with a history of acute myocardial infarction (AMI) and patients with primary hypertension (PH), a highrisk group for arterial thrombosis. Eighty patients with a history of AMI (group A), 160 patients with a history of PH (group B), and 124 age-matched controls without arterial disease (group C) were studied. APC-R was determined using the Coatest APC Resistance Kit of Chromagenix, Sweden. The prevalence of the FV Q506 mutation was estimated by DNA analysis (Bertina method). The prevalence of the FV Q506 mutation was 20%, 13.75%, and 8% in groups A, B, and C, respectively (A v C P = .0466). The prevalence of APC-R was 47.5% in group A v 13% in group C (P < .0001) and 36.25% in group B v13% in group C (P < .0001). The response to activated protein C expressed as mean value +/- SD was 2.05 +/- 0.33 in group A v 2.56 +/- 0.46 in group C (P < .05) and 2 +/- 0.22 in group B v 2.56 +/- 0.46 in group C (P < .05). These findings suggest that patients with a history of AMI or PH have a significantly increased incidence of both APC-R and FV Q506 mutation compared with the control group. These findings support the hypothesis that these anticoagulant defects may be risk factors for arterial thrombosis. (C) 2000 American Journal of Hypertension, Ltd

Elevated plasma immunoreactive leptin levels preexist in healthy offspring of patients with essential hypertension

Background Plasma leptin levels and plasma insulin levels have been found to be elevated in patients with essential hypertension (EH) and have been suggested to be components of the metabolic syndrome. Increased heart rate (HR) may predict the development of EH in normal or borderline-hypertensive individuals. The aim of our study was to test the hypothesis that elevated plasma leptin and insulin levels as well as systolic blood pressure (SBP) and diastolic blood pressure (DBP) and increased resting HR preexist in the healthy offspring of patients with EH. Methods and Results Twenty-six (12 male, 14 female) healthy offspring of hypertensive patients, mean age 16 +/- 2.5 years and body mass index (BMI) of 21.5 +/- 2.8 kg/m(2) (group A), and 30 (14 mole, 16 female) healthy offspring of normotensive patients, mean age 17 +/- 2.3 years and BMI of 21.9 +/- 2.4 kg/m(2) (group B), were studied. (The two groups were matched for sex, age, and BMI). Mean SEP, DBP, resting HR, plasma leptin, and plasma insulin levels (radioimmunoassay method) were determined in the whole study population. Mean SEP, DBP, and resting HR were significantly higher in group A than in group B (120 +/- 12 vs 112 +/- 9.5 mm Hg, 77 +/- 9 vs 72 +/- 7 mm Hg, 79 +/- 8 vs 75 +/- 5 beats/min, P < .01, P < .05, and P < .05, respectively). Plasma leptin and insulin levels were significantly higher in group A than in group B (9 +/- 5.06 vs 5.6 +/- 2.5 ng/ml and 20.11 +/- 11.3 vs 14.8 +/- 5.2 mu IU/ml, P < .01 and P < .05, respectively). Conclusions Our findings support the hypothesis that hyperleptinemia, hyperinsulinemia, and elevated blood pressure and resting HR preexist in the healthy offspring of patients with EH

Chain trapping in diblock copolymers near the ordering transition

The mean-square displacement, <Delta r(2)>, of very high molecular weight diblock copolymers in solutions near the disorder-to-order transition is investigated by pulsed-field-gradient NMR. The thermodynamic potential influencing the motion leads to a time-independent <Delta r(2)> at short times followed by free-diffusional behavior. The plateau is attributed to a trapping of the copolymer chains at the “quasi-interfaces” formed by slow composition fluctuations