Nicotine Increases Impulsivity and Decreases Willingness to Exert Cognitive Effort despite Improving Attention in “Slacker” Rats: Insights into Cholinergic Regulation of Cost/Benefit Decision Making

Successful decision making in our daily lives requires weighing an option’s costs against its associated benefits. The neuromodulator acetylcholine underlies both the etiology and treatment of a number of illnesses in which decision making is perturbed, including Alzheimer’s disease, attention-deficit/hyperactivity disorder, and schizophrenia. Nicotine acts on the cholinergic system and has been touted as a cognitive enhancer by both smokers and some researchers for its attention-boosting effects; however, it is unclear whether treatments that have a beneficial effect on attention would also have a beneficial effect on decision making. Here we utilize the rodent Cognitive Effort Task (rCET), wherein animals can choose to allocate greater visuospatial attention for a greater reward, to examine cholinergic contributions to both attentional performance and choice based on attentional demand. Following the establishment of baseline behavior, four drug challenges were administered: nicotine, mecamylamine, scopolamine, and oxotremorine (saline plus three doses for each). As per previous rCET studies, animals were divided by their baseline preferences, with “worker” rats choosing high-effort/high-reward options more than their “slacker” counterparts. Nicotine caused slackers to choose even fewer high-effort trials than at baseline, but had no effect on workers’ choice. Despite slackers’ decreased willingness to expend effort, nicotine improved their attentional performance on the task. Nicotine also increased measures of motor impulsivity in all animals. In contrast, scopolamine decreased animals’ choice of high-effort trials, especially for workers, while oxotremorine decreased motor impulsivity for all animals. In sum, the cholinergic system appears to contribute to decision making, and in part these contributions can be understood as a function of individual differences. While nicotine has been considered as a cognitive enhancer, these data suggest that its modest benefits to attention may be coupled with impulsiveness and decreased willingness to work hard, especially in individuals who are particularly sensitive to effort costs (i.e. slackers).     

Understanding the basic biology underlying the flavor world of children

Health organizations worldwide recommend that adults and children minimize intakes of excess energy and salty, sweet, and fatty foods (all of which are highly preferred tastes) and eat diets richer in whole grains, low- and non- fat dairy products, legumes, fish, lean meat, fruits, and vegetables (many of which taste bitter). Despite such recommendations and the well-established benefits of these foods to human health, adults are not complying, nor are their children. A primary reason for this difficulty is...     

Characterization of a spirochaete isolated from a case of bovine digital dermatitis

AIMS: The aim of the study was to characterize a spirochaete isolated from the lesions of a cow with digital dermatitis (DD). METHODS AND RESULTS: The characterization was on the basis of its light and electron microscopic appearance, enzymic profile and DNA sequence analysis of its flagellin and 16S rRNA genes. The spirochaete was 6-8-microm long and 0.2-0.3 microm in diameter, and possessed seven to eight periplasmic flagella, with three to five helical turns. The enzymic profile of the bacterium resembles, but is not identical to that of Treponema brennaborense. Its flagellin gene sequence was identical to that of Treponema phagedenis but distinct from that of an ovine spirochaete. Analysis of a 1477-bp region of the 16S rRNA genes indicated that this is a Treponema species and that it is indistinguishable from some isolates made from cases of bovine DD in the United States. Finally, electron microscopy revealed the presence of myovirus-like bacteriophage particles in all cultures of the treponeme examined. CONCLUSIONS: The spirochaete isolate was identified as a Treponema species closely related to some isolates from the United States (by 16S rDNA) and to T. phagedenis (by flagellin gene sequence) and is associated with bacteriophage particles. SIGNIFICANCE AND IMPACT OF THE STUDY: The fact that the isolates with the same or very similar 16S rDNA sequences have been obtained from cases of bovine DD in cattle in different countries at different times, lends further support to the hypothesis that treponemes play a role in the pathogenesis of this disease.     

Biological characterization of an English granulovirus from the summer fruit tortrix moth, Adoxophyes orana

Adoxophyes orana granulovirus (AdorGV) was isolated from overwintering larvae in an orchard in Kent, in the UK. The developmental time of each A. orana instar was determined by measuring the size of the head capsule. The susceptibility of the larvae to the English isolate of AdorGV was evaluated in laboratory bioassays using inoculation by microdroplet feeding and applied dose assays. A series of bioassays were performed to determine LD(50) and ST(50) values for first, fourth and fifth instar larvae. The median lethal doses ranged from 30 occlusion bodies in first instar to 1.36 x 10(6) in fifth instar. The median survival time decreased the later the larvae were infected and ranged from 37 days in first instar to 24 days in fifth instar. Approximately half of the infected larvae released a discharge rich in occlusion bodies from their posterior end prior to death. Approximately 85% of larvae attempted pupation and died as larva-pupa intermediates.     

The flagellin gene as a stable marker for detection of Pseudomonas fluorescens SBW25

Flagellin gene central regions from 111 isolates of Pseudomonas fluorescens SBW25 obtained from soil during a field release experiment were analysed using a combined PCR/RFLP technique to look for variation. In addition, a 858 bp flagellin gene sequence from the original strain and the last isolate obtained from the release site were compared. There was no variation in flagellin gene sequences indicating that the gene was stable over the period of the release, and that the flagellin gene is a suitable marker for use in the detection of bacteria in release experiments. A comparison of Pseudomonas fluorescens SBW25 flagellin with other sequenced flagellins revealed closest homology to the flagellin of Ps. putida PRS2000.     

ABO blood group,secretor state,and susceptibility to recurrent urinary tract infection in women.

ABO blood group and secretor state was determined in 319 women with recurrent urinary tract infection and compared with those of a control group of 334 women of similar age ranges. Women of blood groups B and AB who are non-secretors of blood group substances showed a significant relative risk of recurrent urinary tract infection of 3.12 (95% confidence limits, 1.49 and 6.52) in comparison with other types. This appears to be a genuine example of synergy in which absence of anti-B isohaemagglutinin and secretor substances combines to give an increased risk of recurrent urinary tract infection. Determination of blood group and secretor state may provide additional information in identifying those at risk.