Folliculogenesis is a complex process which describes the maturation of the ovarian follicle, from the primordial stage all the way to the ovulation of the antral follicle, and its sequela, the formation of the corpus luteum (CL). Imitation switch (ISWI) proteins are a class of ATP-dependent chromatin remodelers which mobilize nucleosomes to regulate a number of cellular processes including transcription, replication, and DNA repair. The pattern of expression of the mammalian ISWI proteins SNF2H and SNF2L in the mouse ovary suggests a role in the coordination of the proliferation and differentiation of granulosa cells during folliculogenesis. Here, we report that SNF2H is associated with proliferating granulosa cells, while SNF2L expression is induced following the LH surge which triggers their terminal differentiation into luteal cells. Knockdown of Snf2l by siRNA is sufficient to downregulate the expression of StAR, an important steroidogenic enzyme, and marker of the CL. Furthermore, SNF2L is thought to directly regulate StAR expression by physically binding to its promoter as indicated by chromatin immunoprecipitation (ChIP). In order to identify additional targets regulated by SNF2L, an unbiased microarray screen was developed to look for genes induced by LH in a SNF2L-dependent manner. One of the candidates, Fgl2 is strongly induced at 8h post hCG only in granulosa cells with intact SNF2L activity. Furthermore overexpression of SNF2L is sufficient to induce FGL2, and SNF2L is present on its promoter in the SIGC rat granulosa cell line. Some of the SNF2L binding partners that may be important in this regulation are PR-A and FLI-I, which have been found to interact with SNF2L by IP. Finally we describe here the phenotype of a Snf2l KO mouse which includes multiple reproductive defects, including resistance to superovulation, low secondary follicle counts, and a high incidence of abnormal antral follicles. Taken together these data suggest an important role of ISWI proteins in folliculogenesis, particularly SNF2L, which may regulate multiple genes important for the terminal differentiation of granulosa cells into luteal cells following the LH surge.

Mindin (Spondin 2) is a highly conserved extracellular matrix protein of the Mindin-F-spondin family and a regulator of host innate immunity. Despite its expression in the heart, its role in cardiac stress response is unknown. The objective of this study was to determine the role of mindin following myocardial infarction (MI). C57/BL6 wild-type (mindin+/+) or mindin knockout (mindin-/-) mice were randomized to permanent left anterior descending (LAD) coronary artery ligation or sham operation. Mindin expression level increased maximally on day 7 post MI, but returned to baseline by day 28. Mindin-/- mice showed reduced mortality, rupture rate, cardiac MMP-9/-2 activities, NF-kB activation, cytokines and macrophage recruitment. We concluded that mindin is a significant contributor to mortality and acute adverse remodeling post MI, partly through its unique attributes of innate immune regulator and inhibitor of angiogenesis. Mindin may function as a potential biomarker or therapeutic target post MI.

Mindin (Spondin 2) is a highly conserved extracellular matrix protein of the Mindin-F-spondin family and a regulator of host innate immunity. Despite its expression in the heart, its role in cardiac stress response is unknown. The objective of this study was to determine the role of mindin following myocardial infarction (MI). C57/BL6 wild-type (mindin+/+) or mindin knockout (mindin-/-) mice were randomized to permanent left anterior descending (LAD) coronary artery ligation or sham operation. Mindin expression level increased maximally on day 7 post MI, but returned to baseline by day 28. Mindin-/- mice showed reduced mortality, rupture rate, cardiac MMP-9/-2 activities, NF-kB activation, cytokines and macrophage recruitment. We concluded that mindin is a significant contributor to mortality and acute adverse remodeling post MI, partly through its unique attributes of innate immune regulator and inhibitor of angiogenesis. Mindin may function as a potential biomarker or therapeutic target post MI.

Folliculogenesis is a complex process which describes the maturation of the ovarian follicle, from the primordial stage all the way to the ovulation of the antral follicle, and its sequela, the formation of the corpus luteum (CL). Imitation switch (ISWI) proteins are a class of ATP-dependent chromatin remodelers which mobilize nucleosomes to regulate a number of cellular processes including transcription, replication, and DNA repair. The pattern of expression of the mammalian ISWI proteins SNF2H and SNF2L in the mouse ovary suggests a role in the coordination of the proliferation and differentiation of granulosa cells during folliculogenesis. Here, we report that SNF2H is associated with proliferating granulosa cells, while SNF2L expression is induced following the LH surge which triggers their terminal differentiation into luteal cells. Knockdown of Snf2l by siRNA is sufficient to downregulate the expression of StAR, an important steroidogenic enzyme, and marker of the CL. Furthermore, SNF2L is thought to directly regulate StAR expression by physically binding to its promoter as indicated by chromatin immunoprecipitation (ChIP). In order to identify additional targets regulated by SNF2L, an unbiased microarray screen was developed to look for genes induced by LH in a SNF2L-dependent manner. One of the candidates, Fgl2 is strongly induced at 8h post hCG only in granulosa cells with intact SNF2L activity. Furthermore overexpression of SNF2L is sufficient to induce FGL2, and SNF2L is present on its promoter in the SIGC rat granulosa cell line. Some of the SNF2L binding partners that may be important in this regulation are PR-A and FLI-I, which have been found to interact with SNF2L by IP. Finally we describe here the phenotype of a Snf2l KO mouse which includes multiple reproductive defects, including resistance to superovulation, low secondary follicle counts, and a high incidence of abnormal antral follicles. Taken together these data suggest an important role of ISWI proteins in folliculogenesis, particularly SNF2L, which may regulate multiple genes important for the terminal differentiation of granulosa cells into luteal cells following the LH surge.

No description available.

No description available.

Muscular dystrophy is a disease characterized by skeletal muscle weakness and wasting, but little is known of alterations in the vascular system that occur with this disease. The culprit in many muscular dystrophies is a defective dystrophin-glycoprotein complex (DGC). The DGC is a group of transmembrane proteins that connects the cytoskeleton of muscle cells to the extracellular matrix; it plays a role in mechanotransduction and the maintenance of structural integrity of these cells, and includes the proteins dystrophin and sarcoglycan-delta. The absence of these proteins results in severe muscular dystrophies in humans, and thus knockout mice lacking the genes encoding for dystrophin (mdx mice) and sarcoglycan-delta (sgcd-/- mice) were studied to detect any vascular alterations that occur as a result of a defective DGC. Acute biaxial biomechanical data were obtained through pressure-diameter and axial force-length tests on common carotid arteries of mdx, sgcd-/-, and wild-type mice in the active and passive smooth muscle state. Functional response to the vasoreactive compounds phenylephrine, carbamylcholine chloride, and sodium nitroprusside was also tested. We found significant biomechanical differences between the knockout and wild-type mouse arteries: the mdx and sgcd-/- arteries had decreased distensibilities in pressure-diameter tests, with mdx arteries also having increased circumferential stresses, and the knockout arteries generated increased axial loads and stresses in the axial force-length tests. The mdx and sgcd-/- arteries also differed from the wild-type in that their ‘homeostatic’ axial stretch, at which the axial force remains constant upon pressurization, was significantly decreased. We conclude that the loss of DGC proteins does trigger changes in vascular smooth muscle cells or their interactions with the extracellular matrix, yet that the altered vascular system was able to adapt and function without the DGC. Knowledge of alterations to the vascular system (and adaptations to these changes) of patients with muscular dystrophy could help physicians customize their treatment to extend and enhance their lives, especially as medical advances extend the lifespan of these patients and they begin to suffer from diseases such as hypertension and atherosclerosis that affect the normal aging population.

Gram-negative bacteria decorate their outermost surface structure, lipopolysaccharide, with elaborate chemical moieties, which effectively disguises them from immune surveillance and protects them from the onslaught of host defenses. Many of these changes occur on the lipid A component of lipopolysaccharide, which is crucial for host recognition of Gram-negative infection. Despite its highly inflammatory nature, LPS is a molecule with remarkable therapeutic potential. Lipid A is a glycolipid that serves as the hydrophobic anchor of LPS and constitutes a potent ligand of the TLR4/MD2 receptor of the innate immune system. A less toxic mixture of mono-phosphorylated lipid A species (MPL) recently became the first new FDA-approved adjuvant in over 70 years. Whereas wild-type E. coli LPS provokes strong inflammatory MyD88-mediated TLR4 signaling, MPL preferentially induces less inflammatory TRIF-mediated responses. Here, we developed a system for combinatorial structural diversification of E. coli lipid A yielding a spectrum of bioactive variants that display distinct TLR4 agonist activities and cytokine induction. Mice immunized with engineered lipid A/antigen emulsions exhibited robust IgG titers indicating the efficacy of these molecules as adjuvants. Other types of modification to the lipid A domain, such as altering the length of the fatty acyl chains that anchor LPS to the cell membrane, were found to affect bacterial fitness but not drastically influence detection by the TLR4/MD2 receptor. Overall, this combinatorial approach demonstrates how engineering lipid A can be exploited to generate a spectrum of immunostimulatory molecules for vaccine and therapeutics development as well as for a deeper understanding of bacterial membrane biogenesis. / text

No description available.

Background: Obstructive sleep apnea (OSA) has been associated with atrial enlargement in response to high arterial and pulmonary pressures and increased sympathetic tone. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA; its impact on atrial electrical remodeling has not been investigated however. Signal-averaged p-wave (SAPW) is a non-invasive quantitative method to determine p-wave duration, an accepted marker for atrial electrical remodeling. The objective was to determine whether CPAP induces reverse atrial electrical remodeling in patients with severe OSA. Methods: Prospective study in consecutive patients attending the Sleep Clinic at Kingston General Hospital. All patients underwent full polysomnography. OSA-negative and severe OSA were defined as apnea-hypopnea index (AHI) < 5 events/hour and AHI ≥ 30 events/hour, respectively. In severe OSA patients, SAPW was determined pre- and post-intervention with CPAP for 4 - 6 weeks. In OSA-negative controls, SAPW was recorded at baseline and 4 - 6 weeks thereafter without any intervention. Results: A total of 19 severe OSA patients and 10 controls were included in the analysis. Mean AHI and minimum O2 saturation were 41.4 ± 10.1 events/hour and 80.5 ± 6.5% in severe OSA patients and 2.8 ± 1.2 events/hour and 91.4 ± 2.1% in controls. Baseline BMI was different between severe OSA patients and controls (34.3 ± 5.4 vs 26.6 ± 4.6 kg/m2; p < 0.001). At baseline, severe OSA patients had a greater SAPW duration than controls (131.9 ± 10.4 vs 122.8 ± 10.5 ms; p = 0.02). After CPAP intervention, there was a significant reduction of SAPW duration in severe OSA (131.9 ± 10.4 to 126.2 ± 8.8 ms; p < 0.001). In controls, SAPW duration did not change within 4 - 6 weeks. Conclusion: CPAP induced reverse atrial electrical remodeling in patients with severe OSA as represented by a significant reduction in SAPW duration. / Thesis (Master, Physiology) -- Queen's University, 2011-07-29 12:53:09.134