Role of estrogen receptor/Sp1 complexes in estrogen-induced heat shock protein 27 gene expression

Treatment of MCF-7 human breast cancer cells with 10 nM 17 beta-estradiol (E2) resulted in a 2-fold induction of heat shock protein (Hsp) 27 mRNA levels, and this response persisted for up to 24 h. The 5'-promoter region of the gene was further investigated to identify genomic sequences associated with E2 responsiveness. An Sp1 and half-palindromic estrogen response element (ERE) separated by 10 nucleotides, GGGCGGG(N)10GGTCA, were identified at -105 to -84, and formation of the Sp1/estrogen receptor (ER) complex was investigated by in vitro assays using synthetic Hsp 27-[32P]Sp1/ERE oligonucleotides in a gel mobility shift assay and transient transfection studies using short (-108/-84) and long (-108/+23) 5'-promoter sequences linked to a thymidine kinase promoter and the bacterial chloramphenicol acetyl transferase (CAT) reporter gene (Hsp-CATs and Hsp-CATl, respectively). Incubation of nuclear extracts from MCF-7 cells with an Hsp 27-[32P]Sp1/ERE oligonucleotide results in formation of an Sp1/ER complex. The formation of this complex was inhibited by coincubation with unlabeled Sp1/ERE, ERE, and Sp1 oligonucleotides and by preincubation with ER or Sp1 antibodies (immunodepletion). In addition, the complex was supershifted by coincubation with ER antibodies. Mutation of either Sp1 or ERE sites also decreases formation of the retarded band. E2 induced CAT activity in MCF-7 cells transiently transfected with either Hsp-CATs or Hsp-CATl plasmids. It was also demonstrated that E2 did not significantly induce CAT activity in MCF-7 cells transiently transfected with Hsp-CATl-containing mutations in both the Sp1 and ERE sites. The results of this study demonstrate that an Sp1/ER complex is involved in E2-induced Hsp 27 gene expression.

[Changes of brain potentials related to visual attention during simulated weightlessness]

To study the possible effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) during a simple visual selective response task were compared between head down tilt (HDT) and head up tilt (HUT) in 9 normal subjects. The results were: both the target (T) and non-target (NT) flash signals induced significant slow positive potentials which were supposed to be related to the attention activity; the amplitude of the positive potentials in the frontal regions decreased significantly especially for NT-ERPs during HDT as compared with that during HUT. The data provide new evidence indicating that the ability of brain response declined during simulated weightlessness and more attention should be paid to the study of brain function during space flight.

The effect of head-down tilt on brain potentials related to visual attention

To study the possible effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) in a simple visual selective response task were compared between HDT and HUT in 9 normal subjects. The results were: The Target(T) and non-Target(NT) flash signals both induced significant slow positive potentials which were supposed to related to the attention state; the amplitude of the positive potentials in frontal regions decreased significantly especially for NT-ERPs during HDT compared with that during HUT. The data reported provide new evidence indicating that more attention should be paid on the brain function study during space flight.

Secretion of pancreatic lipase and colipase from rat pancreas

Rat pancreatic juice was collected from female, anesthetized Sprague-Dawley rats (200-250 g) during basal secretion and after 45-min intravenous infusion for secretin or secretin with cholecystokinin (CCK). The volume of secretion was measured as well as activity of lipase and colipase. It was shown that the basal secretion of pancreatic juice gave a colipase/lipase (C/L) ratio of about 0.5. Stimulation with secretin or addition of CCK to secretin gave a C/L ratio between 0.4 and 0.6. This was not significantly different from the ratio found in basal secretion. The secretion of lipase and colipase from isolated pancreatic acini was also found to parallel a C/L ratio equal to 0.6 in the basal release and to a ratio between 0.5 and 0.6 after stimulation with CCK, secretin, or carbachol. The total activity ratio of C/L in the pancreas was equal to 0.97. It is concluded that lipase and colipase are secreted in parallel both in vivo and in vitro. The reason for a lower ratio of C/L in the secreted juice compared to the C/L ratio of pancreatic gland is not known.