We construct and analyze a model network of the pyloric rhythm of the crustacean stomatogastric ganglion consisting of an oscillator neuron that inhibits two reciprocally inhibitory follower neurons. We derive analytic expressions that determine the phase of firing of the follower neurons with respect to the oscillator. An important aspect of the model is the inclusion of synapses that exhibit shortterm synaptic depression. We show that these type of synapses allow there to be a complicated relationship between the intrinsic properties of the neurons and the synapses between them in determining phase relationships. Our analysis reveals the circumstances and ranges of cycle periods under which these properties work in concert with or independently from one another. In particular, we show that phase maintenance over a range of oscillator periods can be enhanced through the interplay of the two follower neurons if the synapses between these neurons are depressing. Since our model represents the core of the oscillatory pyloric network, the results of our analysis can be compared to experimental data and used to make predictions about the biological network.

The process by which hematopoietic stem cells (HSCs) residing in the bone marrow differentiate into blood cells is known as hematopoiesis. In the event of hemorrhagic shock, it is crucial for the HSC to rapidly differentiate into new committed erythroid progenitor cells that will give rise to erythrocytes. Growth factors and cytokines enhance the self-renewing process of HSC and are therefore crucial to restoring normal levels of blood cells in the body. Hematopoietic inducing agents (HIAs) such as the cytokine erythropoietin and granulocyte-colony-stimulating factor play a vital role in hematopoiesis because they are capable of inducing the proliferation of stem cells. The aim of the current study is to mathematically model the effect of HIA on the proliferation rate of hematopoietic stem cells at varying levels of oxygenation. The role of HIA was analyzed by constructing a set of coupled ordinary differential equations upon which mathematical analysis was performed. The model makes predictions of hematopoietic activity during low oxygen levels (ranging from 3% to 15%) similar to conditions ranging from acute blood loss to normal conditions.

Background:Considering how many people obtain information about their health online, the aim of this study was to describe the content of the currently most widely viewed YouTube videos related to concussions and to test the hypothesis that consumer videos would be anecdotal, while other sources would be more informational.Methods:The term “concussion” was used to search for videos with 100,000 or more views on YouTube that were posted in English or Spanish. Descriptive information about each video was recorded, as was information on whether certain content was conveyed during the video. The main outcome measures are sources of upload and content of videos.Results:Consumer videos accounted for 48% of the videos, television based accounted for 50% of the videos, and internet based accounted for only 2% of the videos. None of the videos viewed fell into the professional category. Television based videos were viewed significantly more than consumer or internet based videos. Consumer and television based videos were equally anecdotal. Many of the videos focused on adolescents and were related to sports injuries. The majority of the videos (70.4%) addressed concussion causes, with 48% stating sports. Few videos discussed symptoms of concussion and prevention.Conclusions:The potential for widespread misinformation necessitates caution when obtaining information on concussion on a freely accessible and editable medium, such as YouTube.

For the first time in 50 years, traffic fatalities have increased in the United States (US). With the emergence of technology, comes the possibility, that distracted driving has contributed to a decrease in safe driving practices. The purpose of this study was to describe the content on the popular video sharing site, YouTube to ascertain the type of content conveyed in videos that are widely viewed. The 100 most widely viewed English language videos were included in this sample, with a collective number of views of over 35 million. The majority of videos were television-based and Internet-based. Pairwise comparisons indicated that there were statistically significant differences between the number of views of consumer generated videos and television-based videos (p = 0.001) and between television-based videos and Internet-based videos (p < 0.001). Compared with consumer generated videos, television-based videos were 13 times more likely to discuss cell phone use as a distractor while driving, while Internet-based videos were 6.6 times more likely to discuss cell phone use as a distractor while driving. In addition, compared with consumer generated videos, television-based videos were 3.67 times more likely to discuss texting as a distractor while driving, whereas Internet-based videos were 8.5 times more likely to discuss texting as a distractor while driving. The findings of this study indicate that the videos on YouTube related to distracted driving are popular and that this medium could prove to be a successful venue to communicate information about this emergent public health issue.

BackgroundHematopoiesis is a complex process that encompasses both pro-mitotic and anti-mitotic stimuli. Pharmacological agents used in chemotherapy have a prominent anti-mitotic effect. The approach of inhibiting cell proliferation is rational with respect to the rapidly dividing malignant cells. However, it poses a serious problem with respect to cell proliferation of cell types required for the ‘house-keeping’ operations of the human body. One such affected system is hematopoiesis. Chemotherapy induced anemia is an undesired side effect of chemotherapy that can lead to serious complications. Patients exhibiting anemia or leukopenia during chemotherapy are frequently administered a hematopoietic inducing agent that enhances hematopoiesis.MethodsIn previous work, we derived a mathematical model consisting of a set of delay differential equations that was dependent on the effect of a hematopoietic inducing agent. The aim of the current work was to formulate a mathematical model that captures both the effect of a chemotherapeutic agent in combination with a hematopoietic inducing agent. Steady state solutions and stability analysis of the system of equations is performed and numerical simulations of the stem cell population are provided.ResultsNumerical simulations confirm that our mathematical model captures the desired result which is that the use of hematopoietic agents in conjunction with chemotherapeutic agents can decrease the negative secondary effects often experienced by patients.ConclusionsThe proposed model indicates that the introduction of hematopoietic inducing agents have clinical potential to offset the deleterious effects of chemotherapy treatment. Furthermore, the proposed model is relevant in that it enhances the understanding of stem cell dynamics and provides insight on the stem cell kinetics.