Information Circular 26. Scientific Core Drilling in Parts of Koochiching, Itasca, and Beltrami Counties, North-Central Minnesota, 1987-1989: Summary of Lithological, Geochemical, and Geophysical Results

This report summarizes the results of scientific core drilling undertaken primarily to gain a better understanding of the bedrock geology in north-central Minnesota. The drilling and concomitant mapping were supported by the Minerals Diversification Program of the state legislature. The study area lies in southern Koochiching, northern Itasca and east-central Beltrami Counties. This region was selected because data are suggestive of mineral resource potential, but existing geologic maps were too generalized to guide private minerals exploration efforts. The thick cover of glacial deposits in this region requires bedrock geologic mapping to be based largely on the interpretation of geophysical maps. Core drilling and outcrop mapping identify the rock types responsible for the geophysical patterns. It is hoped that geologic mapping by this method will encourage private minerals exploration. In addition, this mapping is an acceleration of on-going efforts by the Minnesota Geological Survey to produce accurate geologic maps of the state to meet existing and future societal, academic and economic needs. The resulting bedrock geologic map at 1:250,000 scale has been released as Minnesota Geological Survey Open-File Report 89-1 which is being reviewed before formal publication. In the course of the drilling program much information was acquired regarding the thickness and lithology of Quaternary surficial deposits and the locally thick weathered bedrock materials (regolith). No formal plans exist at this time to publish an interpretation of these data, but the data are presented here on the geologic logs

Glycogen synthase kinase‐3 inhibition rescues sex‐dependent contextual fear memory deficit in human immunodeficiency virus‐1 transgenic mice

BACKGROUND AND PURPOSE: A significant number of HIV‐1 patients on antiretroviral therapy develop HIV‐associated neurocognitive disorders (HAND). Evidence indicate that biological sex may regulate HAND pathogenesis, but the mechanisms remain unknown. We investigated synaptic mechanisms associated with sex differences in HAND, using the HIV‐1‐transgenic 26 (Tg26) mouse model. EXPERIMENTAL APPROACH: Contextual‐ and cue‐dependent memories of male and female Tg26 mice and littermate wild type mice were assessed in a fear conditioning paradigm. Hippocampal electrophysiology, immunohistochemistry, western blot, qRT‐PCR and ELISA techniques were used to investigate cellular, synaptic and molecular impairments. KEY RESULTS: Cue‐dependent memory was unaltered in male and female Tg26 mice, when compared to wild type mice. Male, but not female, Tg26 mice showed deficits in contextual fear memory. Consistently, only male Tg26 mice showed depressed hippocampal basal synaptic transmission and impaired LTP induction in area CA1. These deficits in male Tg26 mice were independent of hippocampal neuronal loss and microglial activation but were associated with increased HIV‐1 long terminal repeat mRNA expression, reduced hippocampal synapsin‐1 protein, reduced BDNF mRNA and protein, reduced AMPA glutamate receptor (GluA1) phosphorylation levels and increased glycogen synthase kinase 3 (GSK3) activity. Importantly, selective GSK3 inhibition using 4‐benzyl‐2‐methyl‐1,2,4‐thiadiazolidine‐3,5‐dione increased levels of synapsin‐1, BDNF and phosphorylated‐GluA1 proteins, restored hippocampal basal synaptic transmission and LTP, and improved contextual fear memory in male Tg26 mice. CONCLUSION AND IMPLICATIONS: Sex‐dependent impairments in contextual fear memory and synaptic plasticity in Tg26 mice are associated with increased GSK3 activity. This implicates GSK3 inhibition as a potential therapeutic strategy to improve cognition in HIV‐1 patients