journal

Submitted by jiadam on Sun, 04/23/2017 - 16:16

Gliding assay

Gliding assay are used sometimes an in vitro method to study motor function on microtubules. To make one, you need a cover slip and purified kinesin motors are placed on the bottom of the over slip. Microtubules and kinesins are placed on assay and they essentially glide. For this to be effective, you need fluorescence microscope, fluorescently labeled microtubules,and purified kinesin motor. The microtubules will move and with fluorescence, you can observe the directionality of the microtubules, the rate of movement of the kinesin, and what’s needed for kinesin function. Scientist used this in an experiment with eg5 a kinesin motor and a protein TPX2.

Treating PDAC Metastasis

Submitted by jgirgis on Sun, 04/23/2017 - 14:49

Pancreatic Ductal Adenocarcinoma (PDAC) is the third of the leading cause of cancer-related death in the United States and only 8% of patients diagnosed with PDAC survive past 5 years from point of diagnosis (Indolfi, 2016). Though significant advances have been made in the treatment of other forms of cancer, patients diagnosed with PDAC generally have one of the lowest survival rates, not only because PDAC is a particularly aggressive cancer, but also because its asymptomatic nature in early stages means that it often goes undetected until the solid tumor has metastasized. Even when pancreatic cancer is detected in its early stages and has the potential to be resected via pancreaticoduodenectomy, most patients will go on to develop recurrent or metastatic disease. This is likely due to the development of undetected micrometastases that could not have been identified initially. Knowing this, it is important that research surrounding the treatment of PDAC properly accounts for the nuances associated with a metastatic cancer and how it may differ from common therapies associated with a solid tumor.

            This novel treatment will combine preventative measures to halt any future metastases in patients with Pancreatic Ductal Adenocarcinoma with therapies, which address the changes associated with metastases and already observed in the patient population. Metastasis occurs when the epithelial primary tumor cells break through the basement membrane due to a loss of cell-cell adhesion. As a result, epithelial cells transition to mesenchymal cells, which allows tumor cells to leave the pancreas and enter the bloodstream. At this point of extravasation, tumor cells have the freedom to nest in other areas of the body and become metastatic sites of the primary solid tumor.

Reward and Uncertainty in the Prefrontal Cortex

Submitted by jgirgis on Sun, 04/23/2017 - 13:59

In Daeyol Lee's lecture about reward and uncertaing in the prefrontal cortex in Morrill II, he discussed persistence versus perseveration and how they both depend on uncertainty. Neurons and cortical signals are involved in choice and reward history. In the brain, the medial area of the brain is the most active when it comes to reinforcement signals in the brain. Past, but not future, choice signals are amplified by reward. The main neurons involved in this amplification are SEF, DLPFC, LIP, and ACC. Reward signals are ubiquotilsy represented in the braing. Reward also moduluates other signals in the prefrontal cortex related to previous choices and outcomes, but largely only when they are important for learning.

One experiment Lee discussed was about reinforcement learning during matching pennies. The task involved using a monkey to fixate on a yellow square. Then the monkey had a decision to choose either a green circle on the left or the right of the screen. After the monkey chooses, the computers places a ring on one of the green circles. If the monkey chose the green circle that the computer placed a ring around, then the monkey received juice. If not, then the monkey did not receive juice. The computer is detecting the choices the monkey is making and then switches up which green circle gets a ring around it. Therefore, the monkey realized that there is no point in choosing the same green circle each time. Therefore, the way to maximize the monkey’s reward would be by choosing a green circle randomly, like when playing “rock, papers, scissors, shoot”. The conclusion was therefore monkeys utilized reinforcement to be successful.

As a follow up experiment, they marked single neurons on the monkey’s brain that was performing the task mentioned above to see which ones were most active while the monkey performed the task.

Opioids

Submitted by amprovost on Sat, 04/22/2017 - 12:02

Opioids are some of the most widely used medications to manage pain. These drugs are derived from poppy plants, which have been used recreationally across the world for hundreds of years. The exact mechanism of these drugs are not completely understood, but it is known that these drugs bind to 4 different receptors in the brain, interferring with the natural enzymatic activity on these receptors and also causing changes in the amounts of neurotransmitters released in the brain, namely dopamine and gaba. However, opioids cause a problem due to the fact that these receptors are located throughout the body, which explains the full body affects of opioids, such as opioid induced constipation. These drugs are also strong enough to cause neuroplastic changes in the brain, such as a reduced mass in gray matter. These drugs can also change brain chemistry, causing the brain to stop producing endorphins, as the opioids already fully stimulate the receptors designed for endorphins. This change in brain chemistry is a contributer to the strong addictiveness associated with opioids, as a lack of natural endorphins will leave a brain craving some sort of positive stimulation, which it knows can be derived from opioid use. This is a very relevant issue in today's world, as there is an epidemic of opioid abuse throughout the United States today. Understanding how these drugs work will help scientists to make developments into treating addiction and possibly creating alternate means of pain control.

Perfect Paragraph - Urushiol 1

Submitted by kcapri on Fri, 04/21/2017 - 15:11

Poison ivy is a member of the Anacardiaceae family. Its members include cashews, sumac, and mangos, all of which contain urushiol as well (Aguilar-Ortigoza, 2003). Poison ivy’s history in North America dates back to the early 17th century, and possibly even before that. The first published records of poison ivy in North America date to 1609 in Captain John Smith’s writings about the New World after his voyage from England (Armstrong and Epstein, 2011).  Despite this fact, urushiol was first isolated quite recently in the 1920’s by a Japanese chemist named Rikou Majima (Boyd and Rucker, 2013). He named urushiol after the term urushi, the Japanese name for lacquer tree, due to its coloring. Urushiol is colorless until the allergen is exposed to oxygen in the air, and then turns a dark brown or black color - which gives it the same coloring as lacquer that is used for finishing wood (Boyd and Rucker, 2013).  

Plant Physiology - Discussion of Urushiol 3

Submitted by kcapri on Fri, 04/21/2017 - 15:09

Plants are impeccable chemists and it is critical to understand the chemical traits of urushiol before discussing synthesis. This toxin is a mixture of alkyl catechols that is comprised of a 1,2 dihydroxybenzene ring (Flank, 1986). It is a phenolic compound, which means it consists of a benzene ring with a long hydrophobic side chain consisting of a large number of carbons on the carbon-3 position of the benzene ring, as shown in Figure 2. Depending of the specific plant containing urushiol, the amount of carbons in the side chain differs. While poison ivy and sumac have 15 carbons on its chain, poison oak has 17 carbons.

Urushiol is synthesized in the secretory cells of the resin ducts by the shikimic acid pathway. Resin components are derived from carbohydrates that are produced from photosynthesis.  As shown from Figure 3, Protocatechuic acid is a product of the shikimic acid pathway and then used to produce urushiol (Caspi et al., 2013).

When discussing the amount or concentration of urushiol in plants, it does depend on the growth conditions and the particular season. A study performed by Japanese researchers indicated the percentage compositions of urushiol depending on its unsaturated bonds in Japanese, Korean, and Chinese Rhus vernicifera (lacquer trees). Researchers found that the most abundant urushiol was the triene urushiol at 71%, while the next most abundant was mono-urushiol at 14-16%, and diene urushiol at 5-8% concentration (Tetsuo et al., 2002).

Journal - Discussion of Urushiol 2

Submitted by kcapri on Fri, 04/21/2017 - 15:08

Urushiol is stored all throughout the poison ivy plant in the phloem tissue. It is present in the roots, stems, leaves, and fruits, but not in the pollen. The berries and flowers of the poison ivy plants have the highest concentration of urushiol (Bullock, 2011). This allergen specifically resides in resin ducts, which are specialized structures that are located in the secondary phloem. The resin ducts are lined with  secretory cells, where the urushiol is stored until damage is done to the plant and the resin ducts are ruptured. The function of theses ducts is to secrete a resin, or dilute solution of poison within a liquid medium, that will clog up the site of damage (McNair, 1918). The resin ducts leak out the contents in response to tissue damage of the plant, but the toxin is not a deterrent. It is a liquid bandage, similar to p-protein, that prevents water from leaking out (McNair, 1918). As shown from Figure 1, the epithelial cells form the inner wall of the resin duct, also known as the schizogenous cavity. When the cell walls of the plant split, the internal contents dissolve and the resin leaks into the cavity. To transport urushiol for release, the endoplasmic reticulum within the secretory cells transport the resin components into the intercellular storage space by passage through a porous cell wall into the resin duct (Vassilyev, 2000).

It is important to note urushiol storage in different seasons, as well as in different stages in the plant's life cycle - when death is upon it. Urushiol is stored in poison ivy all year round. It is less abundant in plants in the winter, but still present during this season. It is mostly stored and most potent in the spring and early summer (Reeves, 2000). Urushiol is unique in the sense that it is still stored in dead and dried plants from anywhere from one to five years (Reeves, 2000) . A study was conducted by Bedford Shelmire to test if poison ivy still contained urushiol after the plant was “killed” and damaged in different ways. He took pieces of these plants with urushiol and dried some pieces, crushed some, just washed some, and drowned some, and then tested if urushiol was still present and stored. He found that urushiol was still stored and potent after a year and a half in most cases (Shelmire, 1941).

Journal - Discussion of Urushiol 1

Submitted by kcapri on Fri, 04/21/2017 - 15:07

    Throughout our semester of studying plant physiology, most of the class covered processes of normal plant functions that involved anything from development, growth, and reproduction. These processes are complex and directly involve numerous elements and compounds from the environment that are modified and used in intrinsic metabolic systems. These compounds are called primary metabolites. These metabolites can be anything from sucrose to ethanol to lactic acid to cellulose, and can serve vital purposes in the world -- such as in agriculture by providing the populations with fuel, food, and fiber.

In addition to primary metabolites, secondary metabolites are also present in our world. They function differently than primary metabolites in the way that they are produced through modification of primary metabolite synthases and are not required for the functioning of a plant ("Primary and Secondary Metabolites,” 2015). Yet, they can also serve important roles in plant ecosystems, such as attracting pollinators, giving a plant its color, or even defense against predators. Secondary metabolites,  such as opioids, antibiotics, growth factors, and pigments, can aid in human uses, or they can serve as nasty reminders - such as urushiol, the allergenic component of poison ivy. Urushiol is a secondary metabolite of great interest due to its storage, synthesis, and release, as well as its human and environmental impacts.

Poison ivy is a member of the Anacardiaceae family. Its members include cashews, sumac, and mangos, all of which contain urushiol as well (Aguilar-Ortigoza, 2003). Poison ivy’s history in North America dates back to the early 17th century, and possibly even before that. The first published records of poison ivy in North America date to 1609 in Captain John Smith’s writings about the New World after his voyage from England (Armstrong and Epstein, 2011).  Despite this fact, urushiol was first isolated quite recently in the 1920’s by a Japanese chemist named Rikou Majima (Boyd and Rucker, 2013). He named urushiol after the term urushi, the Japanese name for lacquer tree, due to its coloring. Urushiol is colorless until the allergen is exposed to oxygen in the air, and then turns a dark brown or black color - which gives it the same coloring as lacquer that is used for finishing wood (Boyd and Rucker, 2013).  

Ketogenesis

Submitted by amprovost on Fri, 04/21/2017 - 14:50

Ketogenesis is the biochemical proccess where the liver breaks down fatty acids into ketone bodies in the liver. Ketone bodies are molecules used by the body as fuel, but are not generally not the primary source of dietary fuel in the human body. The primary fuel source is derived from carbohydrates, but in periods of prolonged absence of carbohydrates ketones are utilized to be a fuel source. The proccess where ketones are produced in absence of carbohydrates is referred to as hypoglycemia. This proccess has to be carefully regulated by the body, as ketone bodies produce acidic byproducts in the body. If too many ketone bodies are produced, acidic byproducts can accumulate in the body and lower the pH of the bloodstream, a condition known as ketoacidosis. Ketogenesis is constantly occuring in the bodies of healthy individuals, but it occurs at a very low level. This proccess occurs more frequently in individuals based on a protein and fats centered diet, and in individuals with low insulin, such as type one diabetics.

Microbiome

Submitted by scestero on Fri, 04/21/2017 - 13:43

In a recent study of the microbiome, researchers looked at the effects of distinct birthing methods on the microbiomes of infants. The microbiome is the composition of bacteria that is located in the human intestinal tract. In order to study the microbiome, one has to look at the fecal matter of the subject. The study involved comparing the microbiomes of 98 mothers to their infants. The primary varying factor was whether the infant was born vaginally or via C-section. Out of the 98 infants only 12 infants were born via C-section. As the experiment proceeded, researchers found that vaginally born infants had a microbiome that was 75% similar to that of their mothers. But the infants who were born through a C-section only had a 40% similarity to the mother's microbiome. This drastic change was caused by the bacteria that the child comes into contact with in its first moments of life. An infant's microbiome is shaped by its environment and if it is born vaginally, the infant will have a similar microbiome to the mother. An infant that is born through C-section will obtain a microbiome of whatever is in the air at the moment.

 

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