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Abstract: Several lines of evidence suggest that hormonal changes after menopause may play an important role in the incidence of cognitive dysfunction, and also in the development of Alzheimer’s disease. In this study, we investigated the effect of estrogen on cognitive function in rats under different stress environment. Female rats were divided into four groups: two groups were ovariectomized (OVX) and two were sham-operated. One group each of OVX and sham rats was kept in a normal environment, and the other groups were assigned to a daily restraint stress (6 h/day) for 21 days from 2 months after the operation. Following the stress period, subjects were tested for performance in novel object recognition test and then used for morphological and neurochemical analyses. The OVX plus stress (OVX/stress) group showed a significant impairment of recognition of novel objects, compared with the other groups. The OVX/stress group also showed a marked decrease in the number of pyramidal cells of the CA3 region and levels of brain-derived neurotrophic factor mRNA in the hippocampus. We further examined the effect of estrogen against cognitive dysfunction and hippocampal changes of OVX/stress rats. Vehicle or 17β-estradiol (E2) at 20 μg/day was s.c. administered to OVX/stress rats from 2 days before the stress period to the end of behavioral analysis through an implantable osmotic pump. Chronic E2 treatment decreased stress response and improved the cognitive and morphological impairments relative to vehicle group. These data have important implications for cognition enhancing effect of estrogen treatment in postmenopausal women. [Copyright &y& Elsevier]

Abstract: We have recently found that the combination of ovariectomy (OVX) and chronic restraint stress (CS) causes hippocampal pyramidal cell loss and cognitive dysfunction in female rats and that estrogen replacement prevents the OVX/CS-induced morphological and behavioral changes. In this study, to clarify the mechanisms underlying the OVX/CS-mediated memory impairment further, we examined the roles of cholinergic systems in the OVX/CS-induced memory impairment in mice. Female Slc:ICR strain mice were randomly divided into two groups: OVX and sham-operated groups. Two weeks after the operation, the mice of each group were further assigned to CS (6 h/day) or non-stress group. Following the 3-week-stress period, all mice were subjected to contextual fear conditioning, and context- and tone-dependent memory tests were conducted 1 or 24 h after the conditioning. Overburden with 3 weeks of CS from 2 weeks after OVX impaired context- and tone-dependent freezing and the OVX/CS caused significant Nissl-stained neuron-like cell loss in the hippocampal CA3 region, although OVX and CS alone did not cause such behavioral and histological changes. Replacement of 17β-estradiol for 5 weeks after OVX suppressed OVX/CS-induced memory impairment and hippocampal Nissl-positive cell loss. Furthermore, the OVX/CS mice exhibited a significant decrease in choline acetyltransferase in the hippocampus compared with other groups. The cholinesterase inhibitors donepezil and galantamine ameliorated OVX/CS-induced memory impairment. These data suggest that cholinergic dysfunction may be involved in the OVX/CS-induced conditioned fear memory impairment. Overall, our findings suggest that the OVX/CS mouse model is useful to study the mechanisms underlying estrogen loss-induced memory deficits. [Copyright &y& Elsevier]

Abstract: The oxidative dehydrogenation of propane on Pd2+-incorporated magnesium ortho-vanadate (Pd-ortho-MgVO) was examined, despite the long-held belief that magnesium ortho-vanadate (Mg3V2O8) demonstrates scant catalytic activity in oxidative dehydrogenation. At 0.75 h on-stream, a higher activity than that on magnesium pyro-vanadate (monoclinic Mg2V2O7), which is believed to be one of the more active catalysts for oxidative dehydrogenation, was observed using 5% Pd-ortho-MgVO. Unfortunately, the higher catalytic activity decreased with time on stream due to the rapid abstraction of lattice oxygen from 5% Pd-ortho-MgVO. Although the abstracted lattice oxygen was not regenerated during oxidative dehydrogenation in the presence of excess gaseous oxygen, it was easily regenerated during reoxidation in the absence of propane in the feedstream. Redox cycles of palladium and vanadium species during the catalytic reaction and reoxidation were confirmed using extended X-ray absorption fine structure around the Pd K-edge and 51V magic-angle spinning nuclear magnetic resonance, respectively. The results of the present study suggest that the higher catalytic activity observed using 5% Pd-ortho-MgVO at 0.75 h on-stream can be maintained by using an unsteady-state operation in combination with the catalytic reaction and catalyst reoxidation. [Copyright &y& Elsevier]

Abstract: We have recently found that a combination of ovariectomy (OVX) and chronic restraint stress causes cognitive dysfunction and reduces hippocampal CA3 neurons in female rats and that estrogen replacement suppresses the OVX/stress-induced behavioral and morphological changes. In this study, we examined the effect of Ginkgo biloba extract (EGb 761), a popular herbal supplement, on the cognitive dysfunction and neuromorphological change in OVX/stress-subjected rats. Female Fisher 344 rats were randomly divided into three groups: vehicle-treated OVX, EGb 761 (50 mg/kg) -treated OVX and vehicle-treated sham-operated control groups. Two months after ovariectomy, all animals received restraint stress for 21 days (6 h/day), and were then subjected to a novel object recognition test followed by morphological examination by Nissl staining. EGb 761 was orally administered once daily until the behavioral analysis was done. Treatment with EGb 761 improved memory impairment and neuronal loss of hippocampus in the OVX/stress-subjected group in the same ways as 17β-estradiol. On the other hand, EGb 761 did not affect the loss of bone mineral density and increase in body weight after OVX, although 17β-estradiol attenuated them. These results have important implications for neuroprotective and cognition enhancing effects of EGb 761 in postmenopausal women and suggest that the effects are mediated by a different mechanism from estrogen. [Copyright &y& Elsevier]

The article describes the case of a 64-year-old woman admitted with abdominal distension and epigastric pain and was diagnosed with jejunal cancer arising from heterotopic pancreas using small-bowel radiography and double balloon endoscopy.