An electrophysiological investigation of the relationship between conceptual fluency and familiarity

Brain potentials associated with the manipulation of conceptual fluency in a recognition memory paradigm were recorded. Enhanced fluency was associated with attenuation of the N400 and an increased rate of subjects' endorsing both studied and non-studied items as having been studied ("old" responses) in the recognition test. Differences were also found in latencies previously associated with post-retrieval processing, such that in the setting of enhanced fluency (1) non-studied items were associated with a positive wave from 800 to 1600 ms and (2) items endorsed as "new" were more positive than those endorsed as "old" from 1200 to 1600 ms. The effects on the N400 may be related to the impact of fluency on familiarity, whereas later processing may be involved in the attribution of fluency to prior experience.     

Temperature stabilizing effect of tocopherol on rhodopsin in the pressure of fatty acids studied by differential scanning calorimetry

Institute of Cytology, Academy of Sciences of the USSR. I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Institute of Physiology, Bulgarian Academy of Sciences, Sofia. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. A. Vladimirov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 8, pp. 160–171, August, 1989.     

Origins of the projections of the superior colliculus to the dorsal lateral geniculate nucleus and the pulvinar in the rabbit

The origins of the projections of the superior colliculus to the dorsal lateral geniculate nucleus and to the pulvinar in Dutch-belted rabbits were investigated using horseradish peroxidase (HRP) methods. Following injections of HRP in the dorsal lateral geniculate nucleus, retrogradely labeled neurons were found in the upper two-thirds of the stratum griseum superficiale of the ipsilateral superior colliculus. Most of the labeled somata were spindle-shaped, and their major axes tended to be perpendicular to the surface of the superior colliculus. In contrast, following injections of the pulvinar, labeled neurons were found in the lower third of the ipsilateral stratum griseum superficiale. In these cases, the labeled somata were larger than those labeled following dorsal lateral geniculate injections and were multipolar in shape.     

Fibrolamellar Carcinoma of Liver: A Primary Malignant Oncocytic Carcinoid?

Immunohistochemical and ultrastructural findings in two cases of fibrolamellar carcinoma of the liver and two cases of hepatocellular carcinoma of the common histologic type are described. Ultrastructural examination of both cases of fibrolamellar carcinoma revealed the presence of neurosecretory (NS) granules which were sparse in some cells and abundant in others. Many of the tumor cells had a distinct oncocytic appearance with abundant mitochondria. A portion of the glutaraldehyde-fixed neoplasm was processed for the uranaffin reaction (an ultrastructural cytochemical stain specific for the NS granules of neuroendocrine tissue). Abundant uranaffin-positive granules were found in the neoplastic cells of both cases of fibrolamellar carcinoma, whereas no uranaffin-positive granules were found in hepatocellular carcinoma of the common histologic type. There was no statistical difference in the mean diameter of the uranaffin-positive granules measured from both cases. Immunohisto-chemistry revealed the presence of neuron-specific enolase (NSE) and serotonin in one of the two cases of fibrolamellar carcinoma and no NSE staining in two cases of hepatocellular carcinoma of the common histologic type. These findings suggest that some liver tumors presenting histologically as fibrolamellar carcinoma may be neuroendocrine in nature.     

Pathophysiologic effect of interleukin-1b in the rabbit retina.

Interleukin-1 is a potent immunomodulator and has been shown to initiate many aspects of the inflammatory response. To determine the effects of IL-1b in the central nervous system (CNS), the rabbit retina was used, adjacent to which factors can be injected with minimal trauma and both pathologic and physiologic effects can be monitored. Intravitreal injection of 300 units of IL-1b induced an alteration in the visual evoked potentials (VEP) that was associated with marked intravascular red blood cell accumulations, hemorrhage, and cellular inflammation of the epiretinal vessels. Analysis of these events showed slowing and occasional hyper-excitability of the compound action potential of the optic tract and of the cortical VEP that correlate with the maximum inflammatory response. Histologic studies show the following: no apparent response occurs within the first 1.5 hours after intraocular challenge; and between 3 and 6 hours after injection an extensive intravascular red blood cell accumulation and progressive hemorrhage is accompanied by an increase in the number of mononuclear (MN) cells and the appearance of polymorphonuclear (PMN) cells. Polymorphonuclear cells continue to increase with time to give a single wave of inflammation that peaks 24 hours after injection, while the number of MN cells steadily increases. These events are associated with changes in the permeability of the blood-brain barrier and correlate with the electrophysiologic dysfunctions. Forty-one hours after injection, MN inflammation, reactive gliosis, and residual PMN inflammation are evident. Neutralization with specific antibody inhibited the responses through 6 hours after injection. It is concluded that the rabbit retina provides a valuable model for the in vivo analysis of CNS inflammation.     

Reduced visuospatial performance in children with the D2 dopamine receptor A1 allele

Previous studies suggest a reduced dopaminergic function in subjects with the A1 (minor) allele of the D2 dopamine receptor (DRD2) gene. To explore influences on visuospatial ability as a function of the DRD2 gene, 182 alcohol- and other drug-naive sons (age 10–14) of active alcoholic, recovered alcoholic, and nonalcoholic fathers were administered a visuospatial task (Benton's Judgment of Line Orientation Test) which makes minimal motoric/verbal demands. Visuospatial scores were lower for boys with the A1 allele and for sons of active alcoholics. A1-allele boys made more errors than A2 boys on all 11 of the template lines, with the effect being largest for the rightmost presentations. In contrast, the effect of family history for alcoholism was strongest on both right and left midquadrant presentations. Moreover, separate analyses of the two types of errors produced allele but not family history of alcoholism effects when the two lines were misjudged as farther apart than they actually were and family history but not allele effects where the two lines were misjudged as closer together. These results suggest that polymorphism of the DRD2 gene and family history of alcoholism are dissociable determinants of visuospatial ability and that visuospatial defects previously observed in alcoholics may, in part, be antecedent to their drinking behavior.     

MCP-1-dependent signaling in CCR2(-/-) aortic smooth muscle cells

Monocyte chemoattractant protein-1 (MCP-1, CCL2) is a mediator of inflammation that has been implicated in the pathogenesis of a wide variety of human diseases. CCR2, a heterotrimeric G-coupled receptor, is the only known receptor that functions at physiologic concentrations of MCP-1. Despite the importance of CCR2 in mediating MCP-1 responses, several recent studies have suggested that there may be another functional MCP-1 receptor. Using arterial smooth muscle cells (SMC) from CCR2(-/-) mice, we demonstrate that MCP-1 induces tissue-factor activity at physiologic concentrations. The induction of tissue factor by MCP-1 is blocked by pertussis toxin and 1,2-bis(O-aminophenyl-ethane-ethan)-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, suggesting that signal transduction through the alternative receptor is G(alphai)-coupled and dependent on mobilization of intracellular Ca(2+). MCP-1 induces a time- and concentration-dependent phosphorylation of the mitogen-activated protein kinases p42/44. The induction of tissue factor activity by MCP-1 is blocked by PD98059, an inhibitor of p42/44 activation, but not by SB203580, a selective p38 inhibitor. These data establish that SMC possess an alternative MCP-1 receptor that signals at concentrations of MCP-1 that are similar to those that activate CCR2. This alternative receptor may be important in mediating some of the effects of MCP-1 in atherosclerotic arteries and in other inflammatory processes.     

Effects of digoxin in infants with congested circulatory state due to a ventricular septal defect

Digoxin alone was used to treat a congested circulatory state in 21 infants (mean age, 2.7 months; mean weight, 3.8 kg) with a ventricular septal defect. The dose was adjusted on the basis of pharmacokinetics to achieve a mean steady-state concentration of 1.6 +/- 0.3 ng of digoxin per milliliter of serum. The mean red-cell level of sodium-potassium ATPase fell from 23.1 +/- 7.0 to 12.6 +/- 5.2 nmol per milligram per minute with treatment. Only 6 of the 21 patients had an inotropic response, as reflected by echocardiographic measurements, but the drug was of clinical benefit to 12 infants (including these 6). These results show that not all infants with a congested circulatory state due to a ventricular septal defect benefit from digoxin therapy. Furthermore, in some subjects clinical improvement occurs in the absence of a measurable inotropic response.