Effects of exogenous insulin, glucagon, and somatostatin on islet hormone secretion in the perfused chicken pancreas

The effects of exogenous insulin were examined in the isolated perfused chicken pancreas with the duodenum excluded. At low background glucose (50 mg/dl), exogenous insulin infused at a concentration of 20,000 microU/ml elicited clear stimulation of somatostatin secretion while simultaneously inhibiting glucagon release. When the background glucose concentration was elevated to 750 mg/dl, exogenous insulin, had no effect on either somatostatin or glucagon release. When graded doses of exogenous insulin were infused into the chicken pancreas at low background glucose, low concentrations (200 microU/ml) had little effect on somatostatin or glucagon release, but higher concentrations (2000 and 20,000 microU/ml) had clear effects on both somatostatin and glucagon secretion. Glucagon infused at 100 ng/ml stimulated both insulin and somatostatin release. When somatostatin was infused at 25 ng/ml, clear inhibition of glucagon was seen with insulin inhibited to a lesser extent. This study supports the notion of a negative feedback relation between B and D-cells of the pancreatic islets and suggests a paracrine mediation.     

Multidisciplinary validation study of the da Vinci Skills Simulator: educational tool and assessment device

Despite the increased dexterity and precision of robotic surgery, like any new surgical technology it is still associated with a learning curve that can impact patient outcomes. The use of surgical simulators outside of the operating room, in a low-stakes environment, has been shown to shorten such learning curves. We present a multidisciplinary validation study of a robotic surgery simulator, the da Vinci^® Skills Simulator (dVSS). Trainees and attending faculty from the University of Toronto, Departments of Surgery and Obstetrics and Gynecology (ObGyn), were recruited to participate in this validation study. All participants completed seven different exercises on the dVSS (Camera Targeting 1, Peg Board 1, Peg Board 2, Ring Walk 2, Match Board 1, Thread the Rings, Suture Sponge 1) and, using the da Vinci S Robot (dVR), completed two standardized skill tasks (Ring Transfer, Needle Passing). Participants were categorized as novice robotic surgeon (NRS) and experienced robotic surgeon (ERS) based on the number of robotic cases performed. Statistical analysis was conducted using independent T test and non-parametric Spearman’s correlation. A total of 53 participants were included in the study: 27 urology, 13 ObGyn, and 13 thoracic surgery (Table 1). Most participants (89 %) either had no prior console experience or had performed <10 robotic cases, while one (2 %) had performed 10–20 cases and five (9 %) had performed ≥20 robotic surgeries. The dVSS demonstrated excellent face and content validity and 97 and 86 % of participants agreed that it was useful for residency training and post-graduate training, respectively. The dVSS also demonstrated construct validity, with NRS performing significantly worse than ERS on most exercises with respect to overall score, time to completion, economy of motion, and errors (Table 2). Excellent concurrent validity was also demonstrated as dVSS scores for most exercises correlated with performance of the two standardized skill tasks using the dVR (Table 3). This multidisciplinary validation study of the dVSS provides excellent face, content, construct, and concurrent validity evidence, which supports its integrated use in a comprehensive robotic surgery training program, both as an educational tool and potentially as an assessment device.

How Do People Perceive and Adapt to Any Consequences of Electro Convulsive Therapy on Their Daily Lives?

Great controversy surrounds the use of electroconvulsive therapy or ECT. However, it continues to be used internationally. While research on short term effects of ECT abound, there is limited knowledge about long term impacts of ECT on individuals, especially from the lived experience perspective. The aim of this qualitative study was to gain an in-depth understanding of longer-term lived experiences of ECT and how people navigate any impacts on their daily lives. Twenty-three people participated in semi-structured interviews. Data collection and analysis involved an iterative process. Data were coded into four categories: (1) My ECT experience included physical mechanics, decision making, clinic experiences, post ECT support and attitudes and support of others); (2) Direct impacts of ECT on me encompassed both cognitive and emotional impacts; (3) Impacts on my life comprised daily activities, relationships, ongoing health care; and My strategies incorporated fixing or working around the problem, reframing, using support networks, protecting myself and taking control. Insights gleaned through lived experiences have important implications for other service users, direct service providers and those striving for system reforms that embrace more recovery orientated and trauma informed practices.

     

Characterization of noise sources for two generations of computed radiography systems using powder and crystalline photostimulable phosphors

The performances of two generations of computed radiography (CR) were tested and compared in terms of resolution and noise characteristics. The main aim was to characterize and quantify the noise sources in the images. The systems tested were (1) Agfa CR 25.0, a flying spot reader with powder phosphor image plates (MD 40.0); and (2) the Agfa DX-S, a line-scanning CR reader with needle crystal phosphor image plates (HD 5.0). For both systems, the standard metrics of presampled modulation transfer function (MTF), normalized noise power spectra (NNPS) and detective quantum efficiency (DQE) were measured using standard radiation quality RQA5 as defined by the International Electrotechnical Commission. The various noise sources contributing to the NNPS were separated by using knowledge of their relationship with air kerma, MTF, absorption efficiency and antialiasing filters. The DX-S MTF was superior compared with the CR 25.0. The maximum difference in MTF between the DX-S scan and CR 25.0 subscan directions was 0.13 at 1.3 mm(-1). For a nominal detector air kerma of 4 microGy, the peak DQE of the DX-S was 43 (+/-3)%, which was over double that of the CR 25.0 of 18 (+/-2)%. The additive electronic noise was negligible on the CR 25.0 but calculated to be constant 3.4 x 10(-7) (+/-0.4 x 10(-7)) mm2 at 3.9 microGy on the DX-S. The DX-S has improved image quality compared with a traditional flying spot reader. The separation of the noise sources indicates that the improvements in DQE of the DX-S are due not only to the higher quantum, efficiency and MTF, but also the lower structure, secondary quantum, and excess noise.     

Role of the medial prefrontal cortex in acquired distinctiveness and equivalence of cues

In the present study, the authors examined the role of the medial prefrontal cortex in acquired equivalence and distinctiveness of cues. Rats were placed in 4 experimental contexts (A, B, C, and D) where they received presentations of 2 auditory stimuli (X and Y). In Contexts A and B, X was paired with food and Y was not, whereas in Contexts C and D, Y was paired with food and X was not. Rats that received sham lesions and those with lesions of the medial prefrontal cortex acquired this configural discrimination equally readily. Rats then received many pellets in A but not in C. After this training, sham-lesion rats exhibited more magazine activity in B than in D (an acquired distinctiveness/acquired equivalence effect), whereas those with medial prefrontal cortex lesions did not. These results indicate that the medial prefrontal cortex is involved in the process by which experience with stimuli influences the degree of generalization between them.