The hippocampus and reward: Effects of hippocampal lesions on progressive-ratio responding.

Two experiments investigated the effects of ibotenic-acid lesions of the hippocampus on food-rewarded performance under a progressive-ratio 10 schedule of reinforcement. The results of Experiment 1 indicated that rats with hippocampal lesions showed profound increases in breakpoint and enhancements in the efficiency of responding. In a second experiment the same rats were challenged with prefeeding, increases in the height of the response lever, and the substitution of sucrose-based for grain-based reward pellets. Responding in both groups was similarly reduced by prefeeding and increases in the effortfulness of responding, but lesioned rats were significantly more responsive to the change to sucrose reward. Overall, the results indicated that hippocampal damage increased responding by enhancing the activational or hedonic properties of the delivered food pellets, while not affecting food-motivation or the motor capacity to respond. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Xylazine toxicity--literature review and report of two cases

Protoanemonin is a toxic metabolite which may be formed during the degradation of some chloroaromatic compounds, such as polychlorinated biphenyls, by natural microbial consortia. We show here that protoanemonin can be transformed by dienelactone hydrolase of Pseudomonas sp. strain B13 to cis-acetylacrylate. Although similar Km values were observed for cis-dienelactone and protoanemonin, the turnover rate of protoanemonin was only 1% that of cis-dienelactone. This indicates that at least this percentage of the enzyme is in the active state, even in the absence of activation. The trans-dienelactone hydrolase of Pseudomonas sp. strain RW10 did not detectably transform protoanemonin. Obviously, Pseudomonas sp. strain B13 possesses at least two mechanisms to avoid protoanemonin toxicity, namely a highly active chloromuconate cycloisomerase, which routes most of the 3-chloro-cis,cis-muconate to the cis-dienelactone, thereby largely preventing protoanemonin formation, and dienelactone hydrolase, which detoxifies any small amount of protoanemonin that might nevertheless be formed.     

Short-Range Ultra-Broadband Terahertz Communications: Concepts and Perspectives

We propose the concept of ultra-broadband terahertz communication, based on directed non-line-of-sight (NLOS) transmissions. Potential applications of such a system supporting multi-gigabit data rates are given, and put into the context of currently emerging WLANs/WPANs. The technology and propagation constraints serve as boundary conditions for the determination of the required antenna gain to support ultra-broadband communication. Resulting high-gain antenna requirements will necessitate highly directed transmissions. We propose the use of omni-directional dielectric mirrors to support directed NLOS paths. Their performance is investigated with ray-tracing simulations of a terahertz propagation channel in a dynamic office environment, which is calibrated with measured building-material and mirror parameters. We demonstrate that a directed NLOS path scheme will make a terahertz communication system robust to shadowing. Furthermore, we show that dielectric mirrors covering only parts of the walls will significantly enhance the signal coverage in a typical indoor scenario.     

Heterogeneity of the hippocampus: effects of subfield lesions on locomotion elicited by dopaminergic agonists

Oriented calcium oxalate crystals have been grown beneath phospholipid monolayers at the air-solution interface from supersaturated calcium oxalate solutions. Mature calcium oxalate crystals grown beneath zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayers exhibit the characteristic morphology of calcium oxalate monohydrate (COM) crystals with the elongated (101) crystal face preferentially oriented parallel to the plane of the monolayer. Calcium oxalate crystals grown beneath negatively-charged dimyristoylphosphatidylserine (DMPS) monolayers also show a preferential orientation with respect to the monolayer; they do not, however, exhibit the characteristic COM morphology. Raman spectroscopy strongly suggests that the crystals grown beneath either DPPC or DMPS monolayers are the monohydrate phase of calcium oxalate; therefore, differences in crystal morphology are not due to differences in the crystalline phase. Dimyristoylphosphatidylethanolamine (DMPE), dimyristoylphosphatidic acid (DMPA), eicosanoic acid (C20), and eicosanol (C20-OH) monolayers have also been studied to help elucidate the mechanisms of interaction between the lipid monolayers and the calcium oxalate crystals. We discuss the roles of lattice matching, hydrogen bonding, stereochemistry and electrostatics on crystal orientation and morphology.     

The ball-pivoting algorithm for surface reconstruction

The Ball-Pivoting Algorithm (BPA) computes a triangle mesh interpolating a given point cloud. Typically, the points are surface samples acquired with multiple range scans of an object. The principle of the BPA is very simple: Three points form a triangle if a ball of a user-specified radius p touches them without containing any other point. Starting with a seed triangle, the ball pivots around an edge (i.e., it revolves around the edge while keeping in contact with the edge's endpoints) until it touches another point, forming another triangle. The process continues until all reachable edges have been tried, and then starts from another seed triangle, until all points have been considered. The process can then be repeated with a ball of larger radius to handle uneven sampling densities. We applied the BPA to datasets of millions of points representing actual scans of complex 3D objects. The relatively small amount of memory required by the BPA, its time efficiency, and the quality of the results obtained compare favorably with existing techniques     

Interferometric imaging with terahertz pulses

We demonstrate a new reflection imaging technique using single-cycle pulses, in which the sample to be imaged is placed at the focus of a lens in one arm of a Michelson interferometer. The detected signal is the superposition of the pulses from the two arms of the interferometer, one with a sample and one with a reference mirror. Because of the Gouy phase shift from the lens in the sample arm, these two pulses are nearly π out of phase, and can destructively interfere. This leads to a strong cancellation of the measured waveform and a nearly background-free imaging method. We demonstrate the technique using terahertz time-domain spectroscopy and show that the destructive interference provides enhanced sensitivity to features in the sample that are much thinner than the coherence length of the radiation. This technique could be valuable in any low-coherence tomographic measurement in which the reflected electric field can be measured directly     

Triggering of acute myocardial infarction onset by episodes of anger. Determinants of Myocardial Infarction Onset Study Investigators

PURPOSE: We performed this study to identify prognostic factors in a subgroup of patients with carcinoma of unknown primary site treated with cisplatin combination chemotherapy. PATIENTS AND METHODS: Seventy-nine patients with poorly differentiated adenocarcinoma or undifferentiated carcinoma of unknown primary site were treated on two consecutive phase II chemotherapy protocols. The first protocol consisted of treatment with 3-week courses of cisplatin, etoposide, and bleomycin (BEP). In the second protocol, cisplatin was administered weekly combined with oral administration of etoposide (DDP/VP). To identify prognostic factors, univariate and multivariate analyses were conducted. RESULTS: In the univariate analysis, performance status, histology, liver or bone metastases, and serum levels of alkaline phosphatase and AST were significant variables to predict survival. In the multivariate analysis, performance status and alkaline phosphatase were the most important prognostic factors. CONCLUSION: Good-prognosis patients had a performance score of 0 (World Health Organization [WHO]) and an alkaline phosphatase serum level less than 1.25 times the upper limit of normal (N). These patients had a median survival duration greater than 4 years. Intermediate-prognosis patients were characterized by either a WHO performance status < or = 1 or an alkaline phosphatase level > or = 1.25 N. These patients had a median survival duration of 10 months and a 4-year survival rate of only 15%. The poor-prognosis group had both a WHO performance status > or = 1 and an alkaline phosphatase level > or = 1.25 N. These patients had a median survival duration of only 4 months and none survived beyond 14 months. Treatment strategies for these three groups are discussed. It is suggested that this prognostic model be validated in other patients series.     

The propensity for nonregulatory ingestive behavior is related to differences in dopamine systems: Behavioral and biochemical evidence.

Investigated the relation between properties of dopaminergic neural systems and the predisposition to exhibit nonregulatory ingestive behavior in 54 male Long-Evans rats. It was found that Ss that ate and drank during electrical stimulation of the lateral hypothalamus (ESLH) showed greater behavioral sensitization to a series of amphetamine injections (3 mg/kg) than those that did not exhibit ingestive behavior during ESLH. In addition, footshock stress produced a greater increase in forebrain dopamine utilization in Ss that engaged in nonregulatory ingestive behavior. This evidence is consistent with the hypothesis that there are individual differences in the responsiveness of forebrain dopamine systems that are related to the behavioral predisposition to exhibit nonregulatory ingestive behavior. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The recent decline in mortality from coronary heart disease, 1980-1990. The effect of secular trends in risk factors and treatment

OBJECTIVE: To examine whether secular trends in risk factor levels and improvements in treatment can account for the observed decline in coronary heart disease mortality in the United States from 1980 to 1990 and to analyze the proportional contribution of these changes. DATA SOURCES: Literature review, US statistics, health surveys, and ongoing clinical trials. STUDY SELECTION: Data representative of the US situation nationwide reported in adequate detail. DATA EXTRACTION: A computer-simulation state-transition model of the US population between the ages of 35 and 84 years was developed to forecast coronary mortality. The input variables were estimated such that the combination of values led to an adequate agreement with reported coronary mortality figures. Subsequently, secular trends were modeled. DATA SYNTHESIS: Actual coronary mortality in 1990 was 34% (127,000 deaths) lower than would be predicted if risk factor levels, case-fatality rates, and event rates in those with and without coronary disease remained the same as in 1980. When secular changes in these factors were included in the model, predicted coronary mortality in 1990 was within 3% (10,000 deaths) of the observed mortality and explained 92% of the decline; only 25% of the decline was explained by primary prevention, while 29% was explained by secondary reduction in risk factors in patients with coronary disease and 43% by other improvements in treatment in patients with coronary disease. CONCLUSIONS: These results suggest that primary and secondary risk factor reductions explain about 50% of the striking decline in coronary mortality in the United States between 1980 and 1990 but that more than 70% of the overall decline in mortality has occurred among patients with coronary disease.