Does Physical Contact with a Dog or Person Affect Performance of a Working Memory Task?

ABSTRACT

Working memory (WM) plays a critical role in the execution of a wide variety of cognitive tasks and predicts academic success. This study was designed to compare the impact of the presence of a dog or a person, and physical contact with them, on the performance of a WM task. It also exam- ined whether the impact differed for two dogs, and whether these factors im- pacted arousal during the WM task. College students (n=31, aged 18–23 years) performed a WM task in five counterbalanced conditions; dog-touch, dog-no-touch, person-touch, person-no-touch, and alone. Participants were randomly assigned to one of two dogs; Miniature Poodle (n=16) or Border Collie (n=15). The WM task involved replicating increasingly complicated se- quences of colored lights by touching them on an iPad^®. Linear mixed model analyses revealed there was a significant interaction between collaborator and touch (p=0.05); best WM scores occurred without touch with either the per- son or the dog present, and worst WM scores occurred when the participant was touching a dog. Analyzing WM test during the dog conditions, touch (p=0.027) and dog breed (p=0.042) contributed independently to it; task completion was worse when the poodle was present and better without touch. Physiological measures [heart rate (HR) and heart rate variability] during the ex- periment indicated that the WM task was physiologically arousing (p<0.001) compared with listening, and HR was higher when touching a person than a dog during the task (p<0.046). These results are consistent with facilitation of performance by the presence of an observer. If there is a beneficial effect on cognition from a dog, physical contact with the dog might not be a necessary component. Aspects of the dog (e.g., breed) are also likely factors in WM task performance. This study highlights the importance of situational characteristics in studies evaluating the impact of companion animals.     

Amphetamine Activates an Amine-gated Chloride Channel to Generate Behavioral Effects in Caenorhabditis elegans

Amphetamine is a highly addictive psychostimulant, which is thought to generate its effects by promoting release of dopamine through reverse activation of dopamine transporters. However, some amphetamine-mediated behaviors persist in dopamine transporter knock-out animals, suggesting the existence of alternative amphetamine targets. Here we demonstrate the identification of a novel amphetamine target by showing that in Caenorhabditis elegans, a large fraction of the behavioral effects of amphetamine is mediated through activation of the amine-gated chloride channel, LGC-55. These findings bring to light alternative pathways engaged by amphetamine, and urge rethinking of the molecular mechanisms underlying the effects of this highly-addictive psychostimulant.     

Unmasking Heavily O-Glycosylated Serum Proteins Using Perchloric Acid: Identification of Serum Proteoglycan 4 and Protease C1 Inhibitor as Molecular Indicators for Screening of Breast Cancer

Heavily glycosylated mucin glycopeptides such as CA 27.29 and CA 15–3 are currently being used as biomarkers for detection and monitoring of breast cancer. However, they are not well detected at the early stages of the cancer. In the present study, perchloric acid (PCA) was used to enhance detection of mucin-type O-glycosylated proteins in the serum in an attempt to identify new biomarkers for early stage breast cancer. Sensitivity and specificity of an earlier developed sandwich enzyme-linked lectin assay were significantly improved with the use of serum PCA isolates. When a pilot case-control study was performed using the serum PCA isolates of normal participants (n = 105) and patients with stage 0 (n = 31) and stage I (n = 48) breast cancer, higher levels of total O-glycosylated proteins in sera of both groups of early stage breast cancer patients compared to the normal control women were demonstrated. Further analysis by gel-based proteomics detected significant inverse altered abundance of proteoglycan 4 and plasma protease C1 inhibitor in both the early stages of breast cancer patients compared to the controls. Our data suggests that the ratio of serum proteoglycan 4 to protease C1 inhibitor may be used for screening of early breast cancer although this requires further validation in clinically representative populations.     

Prognostic Value of Lactate and Central Venous Oxygen Saturation after Early Resuscitation in Sepsis Patients

The objective of this study was to evaluate the prognostic value of static and dynamic variables of central venous oxygen saturation (ScvO₂) and lactate in patients with severe sepsis or septic shock who underwent early quantitative resuscitation. We also investigated whether ScvO₂ measured after initial resuscitation could provide additive prognostic value to that of lactate. We analyzed the sepsis registry for patients presenting to the emergency department and included patients with simultaneous measurements of lactate and ScvO₂ at the time of presentation (H0) and 6 hours (H6) after resuscitation. The primary outcome was 28-day mortality and multivariable logistic analysis was used to adjust for confounders. A total of 363 patients were included, and the overall 28-day mortality was 18%. The area under the receiver operator characteristic curve for predicting 28-day mortality was as follows: lactate (H6), 0.81; lactate (H0), 0.73; relative lactate change, 0.67; ScvO₂ (H6), 0.65; relative ScvO₂ change 0.59; ScvO₂ (H0), 0.58. Patients with lactate normalization showed significantly lower 28-day mortality compared to patients without lactate normalization (3% vs. 28%, P<0.01). However, in those who achieved ScvO₂ (H6) ≥70%, there was a significant difference in 28-mortality only in patients without lactate normalization (21% vs. 39%, P<0.01) but no difference in those with lactate normalization (4% vs. 3%, P = 0.71). In multivariable analysis, lactate normalization was significantly associated with 28-day mortality (adjusted odds ratio [OR] for 28-day mortality, 0.20; 95% confidence interval [CI], 0.07–0.54; P <0.01), but ScvO₂ (H6) ≥70% showed only a marginal association (the adjusted OR for 28-day mortality, 0.51; 95% CI, 0.26–1.01; P = 0.05). ScvO₂ (H6) ≥70% was associated with 28-day mortality only in cases without lactate normalization in subgroup analysis (adjusted OR 0.37, 95% CI, 0.18–0.79; P = 0.01). Six-hour lactate was the strongest predictor of 28-day mortality in patients with severe sepsis or septic shock. Six-hour ScvO₂ provided additional prognostic value only in cases where lactate values were not normalized after resuscitation.     

Global patterns in fine root decomposition: climate,chemistry, mycorrhizal association and woodiness

Fine root decomposition constitutes a critical yet poorly understood flux of carbon and nutrients in terrestrial ecosystems. Here, we present the first large‐scale synthesis of species trait effects on the early stages of fine root decomposition at both global and local scales. Based on decomposition rates for 279 plant species across 105 studies and 176 sites, we found that mycorrhizal association and woodiness are the best categorical traits for predicting rates of fine root decomposition. Consistent positive effects of nitrogen and phosphorus concentrations and negative effects of lignin concentration emerged on decomposition rates within sites. Similar relationships were present across sites, along with positive effects of temperature and moisture. Calcium was not consistently related to decomposition rate at either scale. While the chemical drivers of fine root decomposition parallel those of leaf decomposition, our results indicate that the best plant functional groups for predicting fine root decomposition differ from those predicting leaf decomposition.     

Molecular characterization of pig muscle phosphoglucose isomerase

As a corollary to X-ray crystallographic work performed by H. Muirhead, detailed studies on crystalline pig muscle phosphoglucose isomerase have been conducted to establish its basic physical and chemical properties. The enzyme species being investigated by X-ray diffraction has been determined to be isoenzyme III. Its molecular weight in the native state was found to be 132,000, its s⁰₂₀,w value to be 7·25 S. The enzyme is composed of two subunits of equal molecular weight (66,000). Its amino acid composition is largely similar to that of rabbit muscle phosphoglucose isomerase, with the significant exception that the pig muscle isomerase contains only three sulfhydryl groups per polypeptide chain (two of them accessible to titration with p-mercuribenzoate) as compared with twice that number for the rabbit muscle enzyme. This low number of sulfhydryl groups is interpreted as being responsible for the ease with which heavy-atom, isomorphous derivatives could be prepared for the pig muscle enzyme by Shaw & Muirhead (1977).