Patterns of cognitive change over time and relationship to age following successful treatment of Cushing's disease.

Chronically elevated levels of cortisol have been associated with changes in cognitive functioning and brain morphology. Using Cushing's disease as a model to assess the effects of high levels of cortisol on cognitive functioning, 27 patients with Cushing's disease were examined at baseline and three successive follow-up periods up to 18 months after successful surgical treatment. At all follow-up periods, patients were administered cognitive tests as well as measures of plasma and urinary free cortisol. Structural MRIs and a depression measure were taken at baseline and one-year follow-up. Results showed that there is a specific pattern of significant cognitive and morphological improvement following successful treatment. Verbal fluency and recall showed recovery, although brief attention did not. Age of participants was a significant factor as to when recovery of function occurred; younger patients regained and sustained their improvement in cognitive functioning more quickly than older participants. Improvement in verbal recall also was associated with a decrease in cortisol levels as well as an increase in hippocampal formation volume one year after treatment. Overall, these findings suggest that at least some of the deleterious effects of prolonged hypercortisolemia on cognitive functioning are potentially reversible, up to at least 18 months post treatment.     

Phonological features of child African American English.

The production of phonological features of African American English (AAE) was examined for 64 typically developing African American children in the 2nd through the 5th grade. Students read aloud passages written in Standard American English. Sixty of the students read the passages using AAE, and 8 different phonological features were represented in their readings. Phonological features were more frequent than morphosyntactic features. The findings as a whole support use of the taxonomy developed for this investigation in characterizing the phonological features of child AAE.     

Intraocular pressure and aqueous humor flow during a euglycemic-hyperinsulinemic clamp in patients with type 1 diabetes and microvascular complications

Background  

Microvascular complications, including retinopathy and nephropathy are seen with type 1 diabetes. It is unknown whether functional changes in aqueous humor flow or intraocular pressure (IOP) develop in parallel with these complications. This study was designed to test the hypothesis that clinical markers of microvascular complications coexist with the alteration in aqueous humor flow and IOP.     

Involvement of the 12-lipoxygenase pathway of arachidonic acid metabolism in homosynaptic long-term depression of the rat hippocampus

Low-frequency stimulation is associated with long-term depression (LTD) of synaptic efficacy in various brain structures. Like long-term potentiation (LTP), homosynaptic LTD in area CA1 of the hippocampus appears to require NMDA receptor activation, changes in postsynaptic calcium concentration and phospholipase A₂ (PLA₂) activation. Arachidonic acid (AA) is released after the activation of calcium-dependent phospholipases and free AA is rapidly metabolized to a family of bioactive products (the eicosanoids) which are thought to be both intracellular and extracellular messengers. In the present study, we investigated the involvement of the cyclooxygenase and lipoxygenase pathways of AA metabolism in the formation of homosynaptic LTD in the rat hippocampus. Stimulation at 1 Hz for 15 min was used to produce homosynaptic depression in area CA1 of hippocampal slices. LTD induction was partially blocked by bromophenacyl bromide (50–100 μM), a selective PLA₂ inhibitor, and by the a nonselective lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 100 μM). In contrast, the specific cyclooxygenase blocker indomethacin (100 μM) did not significantly reduce hippocampal LTD. Since NDGA interferes with LTD formation, we examined whether specific inhibitors of 5- and 12-lipoxygenases were capable of blocking LTD expression. The 12-lipoxygenase inhibitor baicalein at a concentration of 50 μM reduced LTP formation when given in the bath, an effect that was less pronounced with the 5-lipoxygenase inhibitor AA-861. These data suggest that the activation of endogenous PLA₂ and the formation of 12-lipoxygenase metabolites of AA may be important factors controlling the expression of hippocampal LTD.     

Development and Initial Testing of a Permanently Implantable Centrifugal Pump

Abstract: To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 Limin against 150 mm Hg at 2,500 rpm. The normalized index of hemo-lysis (NIH) value of this pump was 0.0028 g/100 L at 5 Limin against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device.