Relationship between angiotensin II receptor expression and cardiovascular risk factors in Mexican patients with coronary occlusive disease

The density of Angiotensin II (Ang) receptors on tissue surfaces is regulated by multiple hormones, cytokines and metabolic factors and is profoundly affected by various pathological conditions, such as age, diet and environmental conditions. The participation of several cardiovascular risk factors in the regulation of Angiotensin II receptor expression has been incompletely studied. We performed an ex-vivo study with human aortic postsurgical specimens to test the hypothesis that Ang AT1 and AT2 receptor expression in human aortic arteries is associated with the presence of cardiovascular risk factors. We included 31 Mexican patients with coronary artery disease. We evaluated Angiotensin II receptor expression by immunostaining and angiotensin converting enzyme insertion/deletion (ACE I/D) polymorphisms by polymerase chain reaction. AT1 and AT2 receptor expression was increased in the aortic segments from the cardiovascular patients compared with control arteries and in patients with the DD genotype. There was a correlation between increased AT1 receptor expression and the number of cardiovascular risk factors present in the patient. Furthermore, reduction of AT1 expression correlated with the number of drug combinations used in the patients. These correlations were not present with respect to AT2 receptor expression. We suggest that increased AT1 receptor expression is associated with the DD genotype. Thus the presence of several cardiovascular risk factors as well as DD genotype, induce AT1 expression increasing the probability to develop coronary occlusive disease.     

Neural and computational mechanisms of postponed decisions

We consider the mechanisms that enable decisions to be postponed for a period after the evidence has been provided. Using an information theoretic approach, we show that information about the forthcoming action becomes available from the activity of neurons in the medial premotor cortex in a sequential decision-making task after the second stimulus is applied, providing the information for a decision about whether the first or second stimulus is higher in vibrotactile frequency. The information then decays in a 3-s delay period in which the neuronal activity declines before the behavioral response can be made. The information then increases again when the behavioral response is required. We model this neuronal activity using an attractor decision-making network in which information reflecting the decision is maintained at a low level during the delay period, and is then selectively restored by a nonspecific input when the response is required. One mechanism for the short-term memory is synaptic facilitation, which can implement a mechanism for postponed decisions that can be correct even when there is little neuronal firing during the delay period before the postponed decision. Another mechanism is graded firing rates by different neurons in the delay period, with restoration by the nonspecific input of the low-rate activity from the higher-rate neurons still firing in the delay period. These mechanisms can account for the decision making and for the memory of the decision before a response can be made, which are evident in the activity of neurons in the medial premotor cortex.     

Perceptions of Educational Climate in a Canadian Medical Radiation Science Programme

Background

The medical radiation science (MEDRADSC) collaborative program at Mohawk-McMaster (MoMac) Institute for Applied Health Sciences in Hamilton, Ontario, Canada, has used 360° feedback about the program since its inception in 2004, which is still ongoing.

Aim

To measure students’ perception of the educational environment in MEDRADSC using the Dundee Ready Education Environment Measure (DREEM), and investigate perception of the educational environment overall, by specialization, and by gender.

Method

The DREEM instrument was distributed electronically in June 2009 to 105 third-year students from three medical radiation specializations: ultrasound, therapy, and radiography.

Results

With an 83% response rate, students rated their educational climate overall as positive. No significant difference was found between gender or specialization at MoMac.

Conclusion

The DREEM inventory can be used effectively within the medical radiation sciences to measure students' perceptions of educational environment and verify very specific issues relating to each of the five subscales.     

Carbachol “push-pull” perfusion in the reticular formation: Effect on the contiguous multiple-unit activity and other sleep-waking parameters in cats

The effects of carbachol perfusion in the pontine (PRF) and mesencephalic (MRF) reticular formation on contiguous multiple-unit activity (MUA) and other sleep-waking parameters of cats were determined. Perfusion of carbachol into the PRF significantly increased the number of contiguous MUA neuronal spikes. There was a linear relationship between the number of minutes of perfusion and MUA neuronal spikes from the 1st to the 8th minute (estimated 1 to 8 μg), followed by a plateau of maximal MUA activation from the 8th to the 10th minute (estimated 8 to 10 μg), and a subsequent decrease in number of MUA cellular spikes from the 10th to the 11th minute (estimated 10 to 11μg) when the perfusion was discontinued. Concomitantly, the perfusion significantly decreased electromyographic MUA (hypotonia) but it did not systematically modify the mesencephalic reticular formation and other electrophysiologic and behavioral sleep-waking parameters. Perfusion of carbachol into the MRF significantly increased the number of contiguous MUA neuronal spikes. There was a linear relationship between the number of minutes of perfusion and the number of MUA neuronal spikes from the 1st to the 11th minute (estimated 1 to 11 μg) when the perfusion was discontinued. Concomitantly, the perfusion significantly increased electromyographic MUA (hypertonia) and produced a systematic electrophysiologic and behavioral arousal response.