Rat brain glucose transporter-2, insulin receptor and glial expression are acute targets of intracerebroventricular streptozotocin: risk factors for sporadic Alzheimer's disease?

Accumulated evidence suggests that the insulin-resistant brain state and cerebral glucose hypometabolism might be the cause, rather than the consequence, of the neurodegeneration found in a sporadic Alzheimer's disease (sAD). We have explored whether the insulin receptor (IR) and the glucose transporter-2 (GLUT2), used here as their markers, are the early targets of intracerebroventricularly (icv) administered streptozotocin (STZ) in an STZ-icv rat model of sAD, and whether their changes are associated with the STZ-induced neuroinflammation. The expression of IR, GLUT2 and glial fibrillary acidic protein (GFAP) was measured by immunofluorescence and western blot analysis in the parietal (PC) and the temporal (TC) cortex, in the hippocampus (HPC) and the hypothalamus. One hour after the STZ-icv administration (1.5 mg/kg), the GFAP immunoreactivity was significantly increased in all four regions, thus indicating the wide spread neuroinflammation, pronounced in the PC and the HPC. Changes in the GLUT2 (increment) and the IR (decrement) expression were mild in the areas close to the site of the STZ injection/release but pronounced in the ependymal lining cells of the third ventricle, thus indicating the possible metabolic implications. These results, together with the finding of the GLUT2-IR co-expression, and also the neuronal IR expression in PC, TC and HPC, indicate that the cerebral GLUT2 and IR should be further explored as the possible sAD etiopathogenic factors. It should be further clarified whether their alterations are the effect of a direct STZ-icv toxicity or they are triggered in a response to STZ-icv induced neuroinflammation.

Bond strengths of two dental bonding systems.

A new bonding system named Kevloc has been introduced. It is based on acrylization of the metal surface with the goal of preventing the occurrence of a marginal gap between the metal and the resin. The purpose of this investigation was to determine the values of the shear bond strength achieved using the Kevloc technique on Ag-Pd (Auropal SE) and Co-Cr (Basil S) alloys and to compare them with those obtained with the OVS technique. The shear bond strengths were measured with the Smitz-Schulmayer shear test in a universal testing machine for polymer materials. A microscope image analyzer was used to measure the thickness of bonding layers and to reveal the possible occurrence of the marginal gap with both techniques. No marginal gap was detected with either technique. Kevloc provided better results than OVS only in a group of specimens tested after polymerization. Immersion in water and thermocycling reduced the initially high bond strength values of Kevloc specimens, whereas the bond strength values of OVS specimens remained unchanged regardless of which aging treatment was used. Microscopic examination did not reveal the existence of the marginal gap for either bonding system. According to the results obtained, it can be concluded that the Kevloc bonding system does not provide better shearing bond strength than the OVS bonding system.