Effectiveness of Quiz-Enhanced Videocasts for the Review of Foundational Sciences in the Podiatry Curriculum.

Background: Integrated medical curricula commonly require the review of foundational science concepts in the context of clinical applications. A detailed analysis of the Des Moines University second-year medical curricula revealed that such reviews, conducted as hours-long basic science lectures in second-year clinical systems courses, often create undesirable redundancy and can load the curriculum with excessively detailed content. We hypothesized that short, quiz-enhanced videocasts (QEVs) would allow a more focused and efficient review of foundational sciences than traditional lectures.

Spectrophotometric Methods for the Study of Eukaryotic Glycogen Metabolism.

Glycogen is synthesized as a storage form of glucose by a wide array of organisms, ranging from bacteria to animals. The molecule comprises linear chains of α1,4-linked glucose residues with branches introduced through the addition of α1,6-linkages. Understanding how the synthesis and degradation of glycogen are regulated and how glycogen attains its characteristic branched structure requires the study of the enzymes of glycogen storage.

GLYCOGEN ACCUMULATION IN TRICHOMONAS IS DRIVEN BY THE AVAILABILITY OF EXTRACELLULAR GLUCOSE.

The parasitic protist Trichomonas vaginalis is the causative agent of trichomoniasis, a highly prevalent sexually transmitted infection. The organism is known to accumulate substantial deposits of the polysaccharide glycogen, which is believed to serve as a store of carbon and energy that can be tapped during periods of nutrient limitation. Such nutrient limitation is likely to occur when T.

Cloning and characterization of glycogen branching and debranching enzymes from the parasitic protist Trichomonas vaginalis.

The protist Trichomonas vaginalis is an obligate parasite of humans and the causative agent of trichomoniasis, a common sexually transmitted infection. The organism has long been known to accumulate glycogen, a branched polymer of glucose, and to mobilize this reserve in response to carbohydrate limitation. However, the enzymes required for the synthesis and degradation of glycogen by T.

Glycogen synthase from the parabasalian parasite Trichomonas vaginalis: An unusual member of the starch/glycogen synthase family.

Trichomonas vaginalis, a parasitic protist, is the causative agent of the common sexually-transmitted infection trichomoniasis. The organism has long been known to synthesize substantial glycogen as a storage polysaccharide, presumably mobilizing this compound during periods of carbohydrate limitation, such as might be encountered during transmission between hosts. However, little is known regarding the enzymes of glycogen metabolism in T.

Purification and identification of amylases released by the human pathogen Trichomonas vaginalis that are active towards glycogen.

The parasitic protist Trichomonas vaginalis is the causative agent of the sexually transmitted infection trichomoniasis. In the laboratory, T. vaginalis is typically cultured in a serum-containing medium with maltose or glucose as the carbon source.

Digestion of glycogen by a glucosidase released by Trichomonas vaginalis.

Trichomonas vaginalis is a protozoan parasite that is the causative agent of trichomoniasis, a widespread sexually transmitted disease. In vitro culture of T. vaginalis typically employs a medium supplemented with either maltose or glucose and carbohydrates are considered essential for growth.

The antimicrobial effect of boric acid on Trichomonas vaginalis.

Background: The treatment options for trichomoniasis are largely limited to nitroimidazole compounds (metronidazole and tinidazole). Few alternatives exist in cases of recalcitrant infections or in cases of nitroimidazole hypersensitivity. Recently, the intravaginal administration of boric acid has been advocated as an alternative treatment of trichomoniasis.

Expression and characterization of a β-fructofuranosidase from the parasitic protist Trichomonas vaginalis.

Background: Trichomonas vaginalis, a flagellated protozoan, is the agent responsible for trichomoniasis, the most common nonviral sexually transmitted infection worldwide. A reported 200 million cases are documented each year with far more cases going unreported. However, T.

Glycogen accumulation and degradation by the trichomonads Trichomonas vaginalis and Trichomonas tenax.

Several species of trichomonad have been shown to accumulate significant quantities of glycogen during growth, suggesting an important role for this compound in cell physiology. We provide the first analysis of the changes in glycogen content and glycogen phosphorylase activity that occur during in vitro growth of two trichomonad species: Trichomonas vaginalis and Trichomonas tenax. Both species accumulated glycogen following inoculation into fresh medium and utilized this compound during logarithmic growth.

Glycogen storage and degradation during in vitro growth and differentiation of Giardia intestinalis.

Giardia intestinalis is the causative agent of human giardiasis, a common diarrheal illness worldwide. Despite its global distribution and prevalence, many questions regarding its basic biology and metabolism remain unanswered. In this study, we examine the accumulation and degradation of glycogen, an important source of stored carbon and energy, during the in vitro growth and differentiation of G.

Multiple glycogen-binding sites in eukaryotic glycogen synthase are required for high catalytic efficiency toward glycogen.

Glycogen synthase is a rate-limiting enzyme in the biosynthesis of glycogen and has an essential role in glucose homeostasis. The three-dimensional structures of yeast glycogen synthase (Gsy2p) complexed with maltooctaose identified four conserved maltodextrin-binding sites distributed across the surface of the enzyme. Site-1 is positioned on the N-terminal domain, site-2 and site-3 are present on the C-terminal domain, and site-4 is located in an interdomain cleft adjacent to the active site.

A prematriculation intervention to improve the adjustment of students to medical school.

Background And Purpose: The transition from a baccalaureate program to a medical curriculum can be a difficult period for some students. Our study asked whether providing students with review materials and a means of assessing their degree of preparedness prior to matriculation influenced actual and perceived performance in 1st-year basic science courses.

Methods: Didactic review materials in basic science subjects encountered in the 1st year were made available to prematriculants online.

The subcellular localization of yeast glycogen synthase is dependent upon glycogen content.

The budding yeast, Saccharomyces cerevisiae, accumulates the storage polysaccharide glycogen in response to nutrient limitation. Glycogen synthase, the major form of which is encoded by the GSY2 gene, catalyzes the key regulated step in glycogen storage. Here, we utilized Gsy2p fusions to green fluorescent protein (GFP) to determine where glycogen synthase was located within cells.

Regulation of glycogen metabolism in yeast and bacteria.

Microorganisms have the capacity to utilize a variety of nutrients and adapt to continuously changing environmental conditions. Many microorganisms, including yeast and bacteria, accumulate carbon and energy reserves to cope with the starvation conditions temporarily present in the environment. Glycogen biosynthesis is a main strategy for such metabolic storage, and a variety of sensing and signaling mechanisms have evolved in evolutionarily distant species to ensure the production of this homopolysaccharide.

Control of mammalian glycogen synthase by PAS kinase.

The regulation of glycogen metabolism is critical for the maintenance of glucose and energy homeostasis in mammals. Glycogen synthase, the enzyme responsible for glycogen production, is regulated by multisite phosphorylation in yeast and mammals. We have previously identified PAS kinase as a physiological regulator of glycogen synthase in Saccharomyces cerevisiae.

Biochemical characterization of Neurospora crassa glycogenin (GNN), the self-glucosylating initiator of glycogen synthesis.

Glycogenin acts in the initiation step of glycogen biosynthesis by catalyzing a self-glucosylation reaction. In a previous work [de Paula et al., Arch.

Regulation of yeast glycogen phosphorylase by the cyclin-dependent protein kinase Pho85p.

Yeast accumulate glycogen in response to nutrient limitation. The key enzymes of glycogen synthesis and degradation, glycogen synthase, and phosphorylase, are regulated by reversible phosphorylation. Phosphorylation inactivates glycogen synthase but activates phosphorylase.

GNN is a self-glucosylating protein involved in the initiation step of glycogen biosynthesis in Neurospora crassa.

The initiation of glycogen synthesis requires the protein glycogenin, which incorporates glucose residues through a self-glucosylation reaction, and then acts as substrate for chain elongation by glycogen synthase and branching enzyme. Numerous sequences of glycogenin-like proteins are available in the databases but the enzymes from mammalian skeletal muscle and from Saccharomyces cerevisiae are the best characterized. We report the isolation of a cDNA from the fungus Neurospora crassa, which encodes a protein, GNN, which has properties characteristic of glycogenin.

Increased glycogen storage in yeast results in less branched glycogen.

Glycogen is a branched polymer of glucose, synthesized as a reserve of both energy and carbon. The branched nature of glycogen is important for its function and polyglucosan bodies, particles that contain a glycogen-like polymer with reduced branching, are a feature of several disease states. The degree of glycogen branching is thought to be governed by the balance between glycogen synthesis and branching activities.

Glycogen synthase sensitivity to glucose-6-P is important for controlling glycogen accumulation in Saccharomyces cerevisiae.

Glycogen is a storage form of glucose utilized as an energy reserve by many organisms. Glycogen synthase, which is essential for synthesizing this glucose polymer, is regulated by both covalent phosphorylation and the concentration of glucose-6-P. With the yeast glycogen synthase Gsy2p, we recently identified two mutants, R579A/R580A/R582A [corrected] and R586A/R588A/R591A, in which multiple arginine residues were mutated to alanine that were completely insensitive to activation by glucose-6-P in vitro (Pederson, B.

Nutrient-regulated protein kinases in budding yeast.

The ability of cells to react appropriately to nutritional cues is of fundamental importance, and in budding yeast, a small number of intracellular protein kinases, PKA, Snf1p/AMP-activated kinase, TOR, Gcn2p, and the cyclin-dependent kinase Pho85p have key roles. A recently characterized enzyme, PAS kinase, may be a new member of this group of nutritional transducers.

Systematic identification of the genes affecting glycogen storage in the yeast Saccharomyces cerevisiae: implication of the vacuole as a determinant of glycogen level.

At the onset of nutrient limitation, the yeast Saccharomyces cerevisiae synthesizes glycogen to serve as a carbon and energy reserve. We undertook a systematic survey for the genes that affect glycogen accumulation by taking advantage of the strain deletion set generated by the Saccharomyces Genome Deletion Project. The strain collection analyzed contained some 4600 diploid homozygous null deletants, representing approximately 88% of all viable haploid disruptants.

Analysis of respiratory mutants reveals new aspects of the control of glycogen accumulation by the cyclin-dependent protein kinase Pho85p.

The PHO85 gene of Saccharomyces cerevisiae encodes a cyclin-dependent protein kinase that can interact with 10 different cyclins (Pcls). In conjunction with Pcl8p and Pcl10p, Pho85p phosphorylates and regulates glycogen synthase. Respiratory-deficient strains, such as coq3 mutants, have reduced glycogen stores and contain hyperphosphorylated and inactive glycogen synthase.