Different effect of acute and chronic oral metformin administration on glucose and insulin response to bread and to pasta in non-insulin dependent diabetic patients.

The aim of the study was to evaluate whether acute and chronic metformin administration may influence differently the glycaemic and insulin response to foods with high and low glycaemic index (bread and pasta) in twelve non-insulin dependent diabetic (NIDDM) patients. Thirty minutes after a random oral administration of either a placebo or a single 850 mg metformin dose, glycaemic and insulin responses to 90 g white bread or 68 g pasta (corresponding to 50 g carbohydrates) were evaluated within 4 h. All the patients were subsequently treated with metformin (850 mg twice a day) for a month and then glycaemic and insulin responses were evaluated again. The acute administration of metformin lowered glycaemic response to bread at 60 and 90 min (P < 0.02 and P < 0.05, respectively) but not to pasta, without affecting insulin response. Chronic metformin treatment significantly lowered glycaemic and insulin response to both bread and pasta. In conclusion, an acute antihyperglycaemic effect of metformin was demonstrable only when a food with high glycaemic index, such as bread, was eaten. On the contrary, the effect of chronic treatment was always present, independent from the glycaemic index of foods, together with a reduction in insulin response, indicating an enhanced sensitivity to endogenous insulin.

Primary hyperoxaluria in a pediatric dental patient: case report.

A case is presented in which primary hyperoxaluria and oxalosis in a 14-year-old Caucasian female were diagnosed. Generalized root resorption resulted in a remarkable mobility of her maxillary central and lateral incisors, although no bone loss was noted. The management of the patient's dental concerns in this rare heritable metabolic disorder consisted of removing the maxillary incisor teeth and placing two sequential prostheses, which the patient tolerated well. A history of trauma to the maxillary incisors was ruled out, so this case adds previously unreported information to our knowledge about the effect of oxaluria on teeth and oral tissues.

Dipole localization of human induced focal afterdischarge seizure in simultaneous magnetoencephalography and electrocorticography.

Localizations were compared for the same human seizure between simultaneously measured MEG and iEEG, which were both co-registered to MRI. The whole-cortex neuromagnetometer localized a dipole in a sphere phantom, co-registered to the MEG sensor array, with an error of 1.4 mm. A focal afterdischarge seizure was induced in a patient with partial epilepsy, by stimulation at a subdural electrocorticography (ECoG) electrode with a known location, which was co-registered to the MRI and to the MEG sensor array. The simultaneous MEG and ECoG during the 30-second seizure was measured and analyzed using the single, moving dipole model, which is the localization model used clinically. The dipole localizations from simultaneous whole cortex 68-channel MEG and 64-channel ECoG were then compared for the repetitive spiking at six different times during the seizure. There were two main regions of MEG and ECoG activity. The locations of these regions were confirmed by determining the location clusters of 8,000 dipoles on ECoG at consecutive time points during the seizure. The mean distances between the stimulated electrode location versus the dipole location of the MEG and versus the dipole location of the ECoG were each about one (1) centimeter. The mean distance between the dipole locations of the MEG versus the dipole locations of the ECoG was about 2 cm. These errors were compared to errors of MEG and ECoG reported previously for phantoms and for somatosensory evoked responses (SER) in patients. Comparing the findings from the present study to those from prior studies, there appeared to be the expected stepwise increase in mean localization error progressing from the phantom, to the SER, to the seizure.

Conductivities of three-layer live human skull.

Electrical conductivities of compact, spongiosum, and bulk layers of the live human skull were determined at varying frequencies and electric fields at room temperature using the four-electrode method. Current, at higher densities that occur in human cranium, was applied and withdrawn over the top and bottom surfaces of each sample and potential drop across different layers was measured. We used a model that considers variations in skull thicknesses to determine the conductivity of the tri-layer skull and its individual anatomical structures. The results indicate that the conductivities of the spongiform (16.2-41.1 milliS/m), the top compact (5.4-7.2 milliS/m) and lower compact (2.8-10.2 milliS/m) layers of the skull have significantly different and inhomogeneous conductivities. The conductivities of the skull layers are frequency dependent in the 10-90 Hz region and are non-ohmic in the 0.45-2.07 A/m2 region. These current densities are much higher than those occurring in human brain.

A model for frequency dependence of conductivities of the live human skull.

A mathematical model (sigma(omega) approximately equal to A omega alpha, where, sigma is identical with conductivity, omega = 2 pi f is identical with applied frequency (Hz), A (amplitude) and alpha (unit less) is identical with search parameters) was used to fit the frequency dependence of electrical conductivities of compact, spongiosum, and bulk layers of the live and, subsequently, dead human skull samples. The results indicate that the fit of this model to the experimental data is excellent. The ranges of values of A and alpha were, spongiform (12.0-36.5, 0.0083-0.0549), the top compact (5.02-7.76, -0.137-0.0144), the lower compact (2.31-10.6, 0.0267-0.0452), and the bulk (7.46-10.6, 0.0133-0.0239). The respective values A and alpha for the respective layers of the dead skull samples were (40.1-89.7, -0.0017-0.0287), (5.53-14.5, -0.0296 - -0.0061), (4.58-15.9, -0.0226-0.0268), and (12.7-25.3, -0.0158-0.0132).