Regulation of the metabolism of linoleic acid to arachidonic acid in rat hepatocytes

When 5×10⁶ hepatocytes were incubated for 40 min with from 0.15 to 0.60 mM [1-¹⁴C]linoleic acid, [1-¹⁴C]6,9,12-octadecatrienoic acid, or [1-¹⁴C]8,11,14-eicosatrienoic acid, there was a concentration-dependent acylation of radioactive metabolites into both triglycerides and phospholipids. When the concentration of either [1-¹⁴C]linoleic acid or [1-¹⁴C]8,11,14-eicosatrienoic acid exceeded 0.3 mM, there was no further increase in the metabolism of either fatty acid to other (n−6) metabolites. When the concentration of [1-¹⁴C]6,9,12-octadecatrienoic acid exceeded 0.15 mM, there was an apparent substrate-induced inhibition in its metabolism to 8,11,14-eicosatrienoic acid. With all three substrates (0.3 mM), there was time-dependent metabolism to other (n−6) acids. Cells then were incubated simultaneously with 0.3 mM [1-¹⁴C]linoleic acid along with 0.15 to 0.45 mM 6,9,12-octadecatrienoic acid or 8,11,14-eicosatrienoic acid. These exogenous nonradioactive (n−6) acids suppressed but did not abolish the conversion of [1-¹⁴C]linoleate to radioactive arachidonate. These findings suggest that some linoleate is converted to arachidonate without intracellular mixing of 6,8,12-octadecatrienoic or 8,11,14-eicosatrienoic acids. This hypothesis is supported by the finding that exogenous linoleate did not markedly affect the metabolism of [1-¹⁴C]6,9,12-octadecatrienoic or [1-¹⁴C]8,11,14-eicosatrienoic acid by microsomal chain elongating or desaturating enzymes.     

Process components of the Implicit Association Test: A diffusion-model analysis.

The authors present a diffusion-model analysis of the Implicit Association Test (IAT). In Study 1, the IAT effect was decomposed into 3 dissociable components: Relative to the compatible phase, (a) ease and speed of information accumulation are lowered in the incompatible phase, (b) more cautious speed-accuracy settings are adopted, and (c) nondecision components of processing require more time. Studies 2 and 3 assessed the nature of interindividual differences in these components. Construct-specific variance in the IAT relating to the construct to be measured (such as implicit attitudes) was concentrated in the compatibility effect on information accumulation (Studies 2 and 3), whereas systematic method variance in the IAT was mapped on differential speed-accuracy settings (Study 3). Implications of these dissociations for process theories of the IAT and for applications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal Stability of Nitride-Based Diffusion Barriers for Ohmic Contacts to <Emphasis Type="Italic">n</Emphasis>-GaN

The use of TaN, TiN, and ZrN diffusion barriers for Ti/Al-based contacts on n-GaN (n ∼ 3 × 10¹⁷ cm⁻³) is reported. The annealing temperature (600–1,000°C) dependence of the Ohmic contact characteristics using a Ti/Al/X/Ti/Au metallization scheme, where X is TaN, TiN, or ZrN, deposited by sputtering was investigated by contact resistance measurements and Auger electron spectroscopy (AES). The as-deposited contacts were rectifying and transitioned to Ohmic behavior for annealing at ≥600°C. A minimum specific contact resistivity of ∼6 × 10⁻⁵ Ω-cm⁻² was obtained after annealing over a broad range of temperatures (600–900°C for 60 s), comparable to that achieved using a conventional Ti/Al/Pt/Au scheme on the same samples. The contact morphology became considerably rougher at the high end of the annealing range. The long-term reliability of the contacts at 350°C was examined; each contact structure showed an increase in contact resistance by a factor of three to four over 24 days at 350°C in air. AES profiling showed that the aging had little effect on the contact structure of the nitride stacks.     

The aftermath of 9/11: Effect of intensity and recency of trauma on outcome.

Does trauma exposure have a long-term impact on the brain and behavior of healthy individuals? The authors used functional magnetic resonance imaging to assess the impact of proximity to the disaster of September 11, 2001, on amygdala function in 22 healthy adults. More than three years after the terrorist attacks, bilateral amygdala activity in response to viewing fearful faces compared to calm ones was higher in people who were within 1.5 miles of the World Trade Center on 9/11, relative to those who were living more than 200 miles away (all were living in the New York metropolitan area at time of scan). This activity mediated the relationship between group status and current symptoms of posttraumatic stress disorder. In turn, the effect of group status on both amygdala activation (fearful vs. calm faces) and current symptoms was statistically explained by time since worst trauma in lifetime and intensity of worst trauma, as indicated by reported symptoms at time of the trauma. These data are consistent with a model of heightened amygdala reactivity following high-intensity trauma exposure, with relatively slow recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

FITC-poly-D-lysine conjugates as fluorescent probes to quantify hapten-specific macrophage receptor binding and uptake kinetics

PURPOSE: Radiographic tumor response and survival were evaluated in the pediatric and young adult population with germ cell tumor, primary CNS lymphoma, or primitive neuroectodermal tumor receiving intra-arterial carboplatin- or methotrexate-based chemotherapy with osmotic blood-brain barrier disruption (BBBD). PATIENTS AND METHODS: Thirty-four patients with histologically confirmed germ cell tumor (n = 9), primary CNS lymphoma (n = 9), or primitive neuroectodermal tumor (n = 16) were treated at the Oregon Health Sciences University from August 1981 through April 1995. Ages ranged from 1 to 30 years (mean, 18 years). Prior treatments included cranial radiation (n = 10) and chemotherapy (n = 18). All patients underwent extensive baseline neuropsychological evaluation and follow-up evaluation upon completion of the protocol, except for two patients who declined follow-up assessment. RESULTS: Six hundred and forty-five BBBD procedures were performed with no mortality. Significant complications included one episode of tonsillar herniation with no neurologic sequelae, 4% incidence of seizures, and 3% incidence of sepsis or granulocytopenic fever. Ototoxicity was seen in 61% of patients who received carboplatin chemotherapy. Eighty-two percent of the patients had an objective response to treatment, including 62% with complete response and 20% with partial response. For most patients, cognitive functioning was maintained or improved at follow-up; this pattern was statistically significant. Three of the test scores for the seven patients who did not receive radiation therapy showed a cognitive decline of at least one standard deviation. Among the nine patients who received radiation therapy before or after BBBD chemotherapy, 11 test scores showed a decline in cognitive function at one standard deviation or more. DISCUSSION: Durable responses were seen in patients with germ cell tumor and primary CNS lymphoma when treated with BBBD. Primitive neuroectodermal tumor requires post-chemotherapy radiotherapy for a durable response to be attained. Ototoxicity was a major form of toxicity in the patients who received carboplatin, but with the recent introduction of sodium thiosulfate, this problem has been markedly alleviated. Favorable cognitive outcomes appeared more likely for patients treated solely with BBBD chemotherapy and not with radiotherapy. Trends in the results for this sample are similar to those of previous research showing that radiotherapy is associated with cognitive decline. Current alternatives to enhanced drug delivery after BBBD include bone marrow transplantation; however, the increment in drug delivery is less, the number of courses is limited, and the morbidity and mortality are greater for bone marrow transplant than for BBBD. The current results suggest that in future trials, irradiation may not be needed in lymphoma and may not be necessary in some CNS germ cell tumors and that more focal radiotherapy should be further assessed in localized primitive neuroectodermal tumors.