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Blood and Cerebrospinal Fluid Circulations in the Brain and Spinal Cord: An Internet-Based Learning Module

Mon, 18 Feb 2013 05:00:00 GMT

Title: Blood and Cerebrospinal Fluid Circulations in the Brain and Spinal Cord: An Internet-Based Learning Module Authors: Elkheir, Shiraz Abstract: The amount of knowledge and skills that an average university student should learn in any given course is increasing each year. On the other hand, the time dedicated for formal teaching is decreasing for various reasons. New and emerging topics need more time to cover. Newer approaches to learning place more emphasis on self-directed and interactive learning as opposed to didactic methods. Online learning is becoming a very popular method of delivering course materials, with institutions and students alike, that could very well restore the balance between time and content to be learnt. For institutions, it can free up time slots of busy lecture halls and seminar rooms, and valuable faculty time that could be utilized in research. For the learners, it means convenience in terms of when and where to study and at what pace. The topic of "Blood and Cerebrospinal fluid Circulations in the Brain and Spinal Cord" is a good example of anatomical content that can be presented as an online learning module. The idea stemmed from the movement of the medical school at Queen's University to revamp its curriculum with an expected reduction of the hours dedicated to Anatomy. Another initiative came from the clinical residents at the Kingston General Hospital, who expressed the interest of having learning materials made available online for quick reference and refreshment of knowledge. To address those needs and requests of the clinical residents, and to serve students in the Life Sciences, Medicine, and MSc Anatomy programs, an online learning module on the blood and cerebrospinal fluid circulations in the brain and spinal cord was created. Unique to the design of this online module is a virtual dialogue that covers the content of the topic and its appeal to a wide readership. For some it represents most of what they need to know, while for the others it would be an introduction or a quick refresher. It is designed in a way to mimic the interaction between the student and a professor with questions that stimulate and engage the learner. Finally, the basic knowledge presented was fortified with clinical scenarios that describe their application and utility in a clinical setting.

Higher brain neurons succumb to acute stroke-like insult while lower brain neurons strongly resist

Thu, 04 Oct 2012 04:00:00 GMT

Title: Higher brain neurons succumb to acute stroke-like insult while lower brain neurons strongly resist Authors: Brisson, DEVIN Abstract: Pyramidal neurons (PyNs) in ‘higher’ brain are highly susceptible to acute stroke injury yet ‘lower’ brain regions better survive global ischemia, presumably because of better residual blood flow. Here we show that projection neurons in ‘lower’ brain regions of hypothalamus and brainstem intrinsically resist acute stroke-like injury independent of blood flow in the brain slice. In contrast `higher` projection neurons in neocortex, hippocampus, striatum and thalamus are highly susceptible. In live brain slices from rat deprived of oxygen and glucose (OGD), we imaged anoxic depolarization (AD) as it propagates through these regions. AD, the initial electrophysiological event of stroke, is a depolarizing front that drains residual energy in compromised gray matter. The extent of AD reliably determines ensuing damage in higher brain, but using whole-cell recordings we found that all CNS neurons do not generate a robust AD. Higher neurons generate strong AD and show no functional recovery in contrast to neurons in hypothalamus and brainstem that generate a weak and gradual AD. Most dramatically, lower neurons recover their membrane potential, input resistance and spike amplitude when oxygen and glucose is restored, while higher neurons do not. Following OGD, new recordings could be acquired in all lower (but not higher) brain regions, with some neurons even withstanding multiple OGD exposure. Two-photon laser scanning microscopy confirmed neuroprotection in lower, but not higher gray matter. Specifically pyramidal neurons swell and lose their dendritic spines post-OGD, whereas neurons in hypothalamus and brainstem display no such injury. Exposure to the Na+/K+ ATPase inhibitor ouabain (100 μM), induces depolarization similar to OGD in all cell types tested. Moreover, elevated [K+]o evokes spreading depression (SD), a milder version of AD, in higher brain but not hypothalamus or brainstem so weak AD correlates with the inability to generate SD. In summary, overriding the Na+/K+ pump using OGD, ouabain or elevated [K+]o evokes steep and robust depolarization of higher gray matter. We show that this important regional difference can be largely accounted for by the intrinsic properties of the resident neurons and that Na+/K+ ATPase pump efficiency is a major determining factor generating strong or weak spreading depolarizations. Description: Thesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2012-10-02 17:59:20.589

DEVELOPMENTAL ORIGINS OF CARDIOVASCULAR DISEASE: ATRIAL NATRIURETIC PEPTIDE GENE DISRUPTED MICE AS A MODEL OF GESTATIONAL HYPERTENSION

Mon, 01 Oct 2012 04:00:00 GMT

Title: DEVELOPMENTAL ORIGINS OF CARDIOVASCULAR DISEASE: ATRIAL NATRIURETIC PEPTIDE GENE DISRUPTED MICE AS A MODEL OF GESTATIONAL HYPERTENSION Authors: ARMSTRONG, DAVID Abstract: Introduction: Developmental origins of disease refers to the theory that adverse maternal environments influence fetal development and the risk of cardiovascular disease (CVD) in adulthood. To test the hypothesis that gestational hypertension influences the development of CVD in offspring, a novel experimental paradigm was developed using atrial natriuretic peptide gene disrupted mice (ANP-/-). The objective of this thesis was to determine the effect of gestational hypertension on cardio-renal function in offspring. Methods: ANP+/+ females were crossed with ANP-/- males (yielding ANP+/-WT offspring) and ANP-/- females with ANP+/+ males (yielding ANP+/-KO offspring). Previous work has established that ANP-/- dams are hypertensive during pregnancy. Offspring gene expression was measured using qPCR. Offspring arterial blood pressure (BP) was measured with a non-invasive tail cuff system. Offspring left ventricular (LV) function was examined using echocardiography (ECHO). Offspring were treated with normal salt (NS) or high salt (HS) chow for five weeks to assess salt-sensitivity. Daily injections of isoproterenol (ISO) were used to induce cardiac stress in offspring. Collagen deposition was assessed using Masson’s trichrome and picrosirius red staining. Results: Absence of maternal ANP had no effect on either litter size or offspring growth, but caused significant LV hypertrophy in offspring, with no change in LV function. Treatment with ISO resulted in myocardial fibrosis and significant LV diastolic dysfunction with a restrictive filling pattern (increased E/A ratio and E/e’) only in ANP+/-KO offspring. Furthermore, absence of maternal ANP was associated with salt-resistant BP in offspring. Conclusions: Gestational hypertension using the ANP-/- mouse model results in a salt-resistant phenotype in offspring, as well as significant cardiac hypertrophy and an adverse response to activation of the sympathetic nervous system in adult offspring. These data suggest that adverse maternal environments may increase the risk of cardiovascular disease in offspring later in life. Description: Thesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2012-09-18 16:12:01.147

THE EFFECT OF HYPOXIA INDUCIBLE FACTOR-1 ON THE EXPRESSION OF THE COINHIBITORY LIGANDS B7-H3 AND B7-H1 IN CANCER: RELEVANCE TO CANCER IMMUNE ESCAPE

Wed, 15 Aug 2012 04:00:00 GMT

Title: THE EFFECT OF HYPOXIA INDUCIBLE FACTOR-1 ON THE EXPRESSION OF THE COINHIBITORY LIGANDS B7-H3 AND B7-H1 IN CANCER: RELEVANCE TO CANCER IMMUNE ESCAPE Authors: Smallwood, Chelsea Abstract: The interactions between tumour cells and cells of the immune system are important in the natural evolution of cancer, and the acquired immune system plays an integral role in cancer immune escape. B7-H3 and B7-H1 ligands provide coinhibitory signals to T cells resulting in T cell anergy or apoptosis and their expression has been shown to increase in cancer cells. Tumour hypoxia (oxygen concentration below physiological level) is a major contributor to the spread of cancer and resistance to radiation and chemotherapy. We proposed that hypoxia results in the upregulation of the B7 molecules B7-H3 and B7-H1. Furthermore, studies in our laboratory have shown that acquisition of malignant properties in tumour cells exposed to hypoxia can be inhibited by low concentrations of nitric oxide mimetic agents such as glyceryl trinitrate (GTN). Using cultured breast and prostate cancer cells, we investigated whether the hypoxia-inducible factor HIF-1α, would mediate an upregulation of these ligands. Using a mouse model, we investigated the effect of GTN on tumour growth in vivo. For the in vitro studies, we exposed MDA-MB-231 and MCF-7 breast cancer cells and DU-145 prostate cancer cells to standard culture conditions, hypoxic conditions, or 100 μM CoCl2 (stabilizes HIF-1α) for 24 hours. Our findings indicate that B7-H3 mRNA was upregulated in hypoxia (P = 0.0101). Contrary to our hypothesis, B7-H3 protein was not upregulated in hypoxia. Interestingly, increased B7-H1 protein expression correlated with increased HIF-1α expression (r2=0.48, P<0.0001), and HIF-1α bound to the hypoxia response element (HRE) of B7-H1. These results indicate a role for HIF-1α in the upregulation of B7-H1 levels in MDA-MB-231 cells. While in vitro studies indicated no effect of GTN, a study using female BALB/c mice injected with 4T1 mammary carcinoma cells resulted in a decrease in tumour volume in the GTN treated mice. Together, these results indicate a novel role for HIF-1α in the up-regulation of B7-H1 on cancer cells, thus potentially contributing to immune escape of cancer cells and additionally, a role for GTN as a possible breast cancer therapy. Description: Thesis (Master, Anatomy & Cell Biology) -- Queen's University, 2012-08-15 11:10:06.237