Chem 13H Elements of Life Posters 2006

Since the beginning of America's weight-loss craze, there have been searches for the one miracle supplement that will help people shed those extra pounds with hardly any work on their part. One of the attempted supplements is chromium picolinate. The theory behind chromium picolinate is that it increases the effectiveness of insulin by stimulating insulin receptors. When insulin is more efficient, blood sugar is reduced and energy is taken from fat deposits, reducing weight. Research on the effectiveness of chromium picolinate on substantial weight loss is not conclusive (as with any new technology), but research is promising that when combined with a healthy weight loss program, chromium picolinate can be an effective agent in helping to lose weight. Research on drosophila melanogaster shows that when the flies are given chromium picolinate, some developed lethal genetic mutations and/or became sterile. The human implications of this study have yet to be determined.

Discovered in ancient times, lead is a soft and extremely toxic metal.  It once had many purposes in everyday life, including being used in paint, gasoline, and water pipes.  By the late 1970’s, lead was determined to have hazardous effects in humans, especially in children.  Even very minute amounts of lead in the bloodstream can cause high blood pressure, nerve disorders, and organ damage.  Children age 6 and younger are particularly vulnerable, as their bodies are at a time of rapid growth and development.  Lead can enter the body by eating, drinking, or inhaling anything containing it.  From there, it is toxic to many enzymes and tissues, including those in which it accumulates: bone marrow, nerve tissue, the brain, and the kidneys.  Lead poisoning often times shows no physical symptoms, making it undetectable before it is too late.  Recently, it was determined that the chemistry behind lead binding might hold the answer to why it is so dangerous.

Calcium plays an important role in many bodily functions. The skeleton and teeth contain a large percentage of calcium, and neurotransmission also depend on calcium to function properly. In order to obtain the calcium necessary for life, our bodies need to absorb it from the food we eat. However, calcium absorption is highly dependent on vitamin D—which can be obtained either through dietary sources or synthesized by the skin when exposed to sunlight. The activated form of vitamin D—1, 25 (OH)₂D₃—facilitates the active absorption of calcium in different sections of the small intestine, where 90% of calcium absorption takes place. To do this, vitamin D acts in three important ways—synthesizing epithelial calcium ion channels for calcium transfer, triggering the formation of intracellular calbindins for increased intracellular diffusion, and helping to regulate basolateral membrane calcium pumps to move calcium against electrochemical gradients. The effects of vitamin D in different sections of the small intestine are controversial and are currently being studied in rats and dogs. Additionally,several studies have investigated the link between overall bone health and vitamin D intake.

Magnesium has been proven to be an extremely important and versatile element in the human body. It is involved in over 300 physiological processes, notably muscle function. By examining the crucial role of magnesium in the ATP production cycle, it is possible to see how the chemical properties of this element affect the body and its motion. In addition, the importance of magnesium can be viewed through the symptoms of a diet low in magnesium. Fortunately, there are magnesium supplements which reduce the effect of these symptoms in more ways than one.

Manganese, like iron, calcium, and zinc is an important trace element in the human body. It aides in the production of certain enzymes, helps regulate blood sugar levels, supports the immune system, and assists in bone formation. It is also a component in manganese superoxide dismutase, an antioxidant found primarily in mitochondria. This compound, also known as MnSOD, seeks out toxic O₂^- free radicals created during mitochondrial respiration. Though O₂^- decomposes spontaneously into O₂ and H₂O₂, MnSOD catalyzes this reaction, causing superoxide to decompose almost as quickly as it is formed, preventing it from harming the cell. It is important, however, to maintain a certain level of manganese in the body as too much can cause neurodegeneration and too little will allow free radical O₂^- to run rampant.

Technetium’s best known isotope, Tc-99m, is administered in roughly 7 million medical procedures in the United States each year.¹ Tc-99m’s widespread use can be credited to its relatively short half-life of about six hours and its x-ray emission energy of about 140 KeV, which make it nearly ideal for nuclear imaging.² For these reasons, Tc-99m is used for a variety of medical imaging procedures. Myocardial perfusion imaging (MPI) is one widely used diagnostic imaging procedure that works on the basis of injecting a low dose of a radioactive tracer into the blood and then detecting the emitted gamma radiation with a large detector rotating about the patient’s chest. The resulting image shows the perfusion of the blood into the heart muscle. Technetium-99m methoxyisobutylisonitrile (MIBI) is a MPI tracer frequently used to diagnose patients with congestive heart failure (CHF) and quantify the extent of the heart failure.

Osteoporosis results when either bone formation by osteoblasts is reduced or bone resorption by osteoclasts is accelerated. Current drugs to treat osteoporosis fall into two categories: anabolic drugs, which stimulate bone formation, and antiresorptive drugs, which inhibit bone resorption. A new drug, strontium ranelate, combines both effects by stimulating bone formation while at the same time inhibiting bone resorption. This results in increased bone mass without affecting bone mineralization, and therefore fewer bone fractures in patients with osteoporosis. While the exact mechanisms through which strontium works are unknown, different methods have been postulated and are currently being researched.

Overall, zinc is known to be a cofactor in over 300 enzymes. This presentation will refer to a reaction requiring zinc in the immune system. Zinc promotes the immune system’s early warning defense system by complexing with glycoproteins and protein tyrosine kinases specifically involved with communication between B-lymphocytes, or macrophages, and helper T-lymphocytes. This allows the helper T-cells to learn about possible threats with respect to their type and prevalence. As a consequence, macrophages can start producing antibodies with this information quickly. The zinc complexing depends on zinc being prevalent for the reaction, and is thus concentration dependent. Lowering zinc concentrations inhibits the complexing and lowers the amount of communication between the T-cells and the macrophages.

Sodium in Membrane Transport and Signal Transduction

Andrew Shevchuk
Sodium

One of sodium’s most important roles in the body is to create an action potential in neurons. This is an electrical signal that travels along the membrane of a cell sending messages between tissues. An action potential behaves like the current in a circuit and thus requires a voltage to propagate. The movement of sodium ions across the cell membrane creates this voltage in the span of milliseconds by a process called depolarization. The sodium ions travel across the membrane through either ligand-gated or voltage-gated ion channels. Ion channels only allow a specific ion through. In the case of sodium, the ligand-gated channels allow ions to move into the cytoplasm when activated by acetylcholine while the voltage-gated channels simply require a large enough electric potential to allow ions through. This method of creating and stimulating action potentials is the primary way signals travel through the body. The presentation will detail these topics.

The sodium-potassium pump is one of the most important biological pumps in the human body. This active transport mechanism regulates the voltage potential of cell membranes, which allows for the action potential of a nerve impulse to occur. Three sodium ions from inside the cell bind to a protein embedded in the cell membrane. This action causes the enzyme to transform its shape, release the Na₊₁ ions into the surrounding environment and admit two K₊₁ ions into the cell. The importance of the relative ion concentrations and use of energy will be discussed. The entire process of nerve impulse will also be summarized and presented in a clear manner in order to enhance the topic of discussion. If time permits, I will also touch upon disorders that arise when this pump malfunctions. I will be working in conjunction with Andrew, who has the element sodium.

Lithium has been used as a medication to treat bipolar disorder, and although biologists are not completely certain as to why this occurs, they have attributed it to the effect that the element has on neurotransmitters. It is thought to restore the balance among signaling pathways and react with signal transduction mechanisms, which triggers long-term changes in neuron-signaling patterns. Lithium also leads to neuroplastic changes and, in turn, mood stabilization, which aids in the treatment of bipolar disorder.

As a naturally occurring transition metal, Cobalt has an artificial isotope that is widely used in the field of medicine. As one of the medical applications, the radioactive cobalt has been used in radiotherapy with its high emission of gamma rays. In 1951, the isotope, Cobalt-60, was used to create the “cobalt bomb” machine in Canada, and since then, has been revolutionized to aid in the medical therapy for cancer treatment. In all, cobaltic radiotherapy has been a great improvement to the world of scientific medicine.

Urea is a waste product found in many organisms, including all mammals, and therefore humans. Humans, for example, excrete approximately 10 kg of urea per year, human urine being comprised of approximately 0.4 to 0.5 M urea. Urease is an enzyme, or biological catalyst, found mainly in bacteria, but also in fungi and a few invertebrates. The purpose of urease is to catalyze the hydrolysis of urea to yield ammonia and carbamate, which spontaneously decomposes to form carbonic acid and a second molecule of ammonia.¹ The bacteria use this reaction primarily as a producer of a source of nitrogen and therefore growth. Although not affecting humans directly, urease is a potential cause of harm in humans in other ways, arising from interactions with bacteria. An example of this is infection-induced urinary stones. This arises from microbial urease-induced alkalinization of urine due to the presence of excess NH₃, which leads to supersaturation of polyvalent anions. This results in their precipitation as urinary stones. 15 to 20% of all urinary stones are accounted for by this. Other sources of damage to the human body include Urease-induced increases in toxicity leading to tissue damage, including damage to the liver, and inflammation.²

Copper: can’t live with it, can’t live without it!

Mackenzie Brady
Cu

Copper is a trace mineral that affects a vast array of body systems. Because of its redox reactivity with oxygen gas, Cu’s effects are far reaching and include the catalyzation of hemoglobin to transport oxygen, spurring energy release by oxidizing glucose as well as improving neurotransmitters like norepinephrine, dopamine and epinephrine levels.   However, copper cannot escape its toxic metal status; thus, when Cu homeostasis is disrupted as seen in Menke’s Disease patients, critical damage results. Menke’s disease is caused by the over expression of ATP7A, the protein that regulates Cu transport across a membrane. This gene mutation inhibits the transportation of Cu from its intestinal storage and therefore restricts oxygen flow, which results in “kinky” hair, convulsions, mental retardation and ultimately death. Possible treatments range from Cu injections to gene manipulation.

Complex protein structures play an essential role in determining amino acid functions.  An important structural component for many proteins are disulfide bridges, which connect two cysteines to form what is called a cystine.  This occurs because of the oxidation states of the disulfide bond. They are the main mechanism for covalent amino acid bonding along side chains. While these bonds occur in our own bodies, they also occur in poisonous venoms found in snakes and other reptiles.  Most snake venoms have around sixty to seventy amino acids, with four to five disulfide bridges.  Slight variations in these venom structures affect the human body in significantly different ways.

Selenium has gained major interest in the past decade in the scientific world. It is essential to the maintenance of the human body. Selenium is found in the form of selenoproteins, which serve numerous functions throughout the body. Recently, groundbreaking evidence has been found concerning the correlation between the amount of selenium in a human’s body and the prevention of cancer, and reduction of mortality rates in cancer patients. It has been found that an increased intake of selenium reduces the risk of many cancers, especially prostate cancer and for patients who are already diagnosed with cancer evidence has shown that the mortality rate of these patients decreased with an increased intake of selenium. Selenium has been found to be so helpful because it is a potent antioxidant. In addition it helps protect cells from damage, and aids cells in repairing themselves. Research is being continued in efforts to help discover the important link between cancer and selenium.

Silicon is the 2nd most common element, but is rarely used in its elemental form in scientific instances. The polymer form of silicone is much more common in science and has been used for medical implants. The use of silicone for breast implants has since been phased out due to medical reactions to leaking implants.

The term dioxin usually refers to the molecule 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), although it also generally describes any of the polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). These are organic compounds with chlorine atoms bonded to various points on the carbon rings. Although industrial regulations have induced a decline in the amount of dioxins in the environment, they degrade slowly and accumulate in the body as a result of their lipophilic properties. For these reasons, it is believed that all humans have some amount of dioxin in their bodies. TCDD is known to cause a variety of ailments in humans, including chloracne, liver damage, damage to the immune, reproductive, and nervous systems, and certain types of cancer. Much evidence suggests that the aryl hydrocarbon receptor (AhR)/AhR Nuclear Translocator (ARNT) signaling pathway mediates TCDD’s toxicity, but it not yet certain how exactly this occurs.

Despite the abundance of fluorine on earth, fluoride concentrations in surface water are low and fluorinated metabolites are extremely rare. Dissolved fluorine is largely excluded from biochemistry due to its highly electronegativity and its high redox potential that precludes a haloperoxidase-type mechanism in biochemistry. 5’-FDAS is the only enzyme that can convert fluoride to organic fluorine that has been described. 5’-FDAS is found in Streptomyces cattleya. S. cattleya can form carbon-fluorine bonds and must therefore have evolved and enzyme able to overcome the chemical challenges of using aqueous fluoride. By using mutiwavelength anomalous diffraction, the sequence and the three-dimensional structure of 5’-FDAS is revealed.

Titanium Dioxide, Stretching Hydrogen to Save Lives

Elizabeth Morin
Titanium

Chemists study the interaction of various forms of matter, and engineers seek to utilize the interactions of matter to create structures. Here, at Penn State, materials engineers (Dickey) and electrical engineers (Grimes) have employed their understanding of titanium dioxide in creating a sensor for molecular hydrogen. In a process called chemisorption, a layer of hydrogen accumulates on the exposed surfaces of titanium dioxide nanotubes, and the sharing of electrons that led to this accumulation changes the conductivity and hence, resistance, of the titanium dioxide. The titanium dioxides are incorporated into circuit nodes whose job is to periodically transmit resistance values to a computer. Employing this resistance data, the computer determines the initial hydrogen concentration of the sample. An elevated hydrogen concentration level in the human breath- on the order of tens of ppm- serves as a good indication of neonatal necrotizing entercolitis (NEC), a pathogen that generates molecular hydrogen bubbles in the human stomach and often attacks preterm infants. This cross-discipline approach has lead to a sensor that will save lives.

Barium is not naturally involved in any biological processes, and it is not very common in nature. Most of the barium in the environment is a byproduct of industry; barium is used in tiles, paints, drilling mud and a variety of other non-biological products and procedures, but this has nothing to do with my poster. The only legitimate medical use of barium is to make the esophagus, stomach, intestines, or rectum visible to x-rays. This is accomplished either through oral ingestion or through enema. My poster presentation will have to focus on the gross intricacies and interesting implications of the use of barium for X-rays, particularly on a new drug called VoLumen that greatly enhances the effectiveness of Barium Sulfate as a contrast agent for Computer Tomography scans of the gastrointestinal tract.

The human body, on average, contains 14 milligrams of iodine. Iodine is used principally by the human endocrine system as a component of certain hormones. Triodothyronine (T-3), which contains three iodine molecules, is one such hormone. The formation of triodothyronine is accomplished by the coupling of two iodotyrosine molecules, and is complicated by the positions of the bulky iodine atoms on the tyrosine rings. Additionally, both the metabolic activity and binding ability to thyroxine-binding globulin of triodothyronine depend on the arrangement of one of the iodine atoms within the molecule. My presentation will focus on these two structural aspects of the iodine-containing hormone triodothyronine.

The coordination compound of platinum, cis-dichlorodiammineplatinum(II) or cisplatin, is a common component in present chemotherapy drugs. It has been shown that doses of cisplatin are effective in combating certain types of cancer. The chemistry behind cisplatin’s anti-tumor action is not completely understood, but it is believed that the compound attaches itself to nucleobases in DNA preventing replication. Unfortunately, it is likely that the same characteristics that account for cisplatin’s effectiveness in destroying tumors are also the cause of its high toxicity and destruction of bodily organs, particularly the liver. A better understanding of cisplatin’s anti-cancer mechanisms will improve the effectiveness chemotherapy and reduce devastating side-effects on cancer patients.

Boron, a metalloid, plays an important role in the development of certain plants. An excess of boron, considered to be a concentration higher than 80 ppm in the leaves, in any plant will be toxic. However, for vegetables and orchard fruits, especially cauliflower, celery, radishes, and apples, a moderate amount of boron (20-60 ppm) is crucial for carbohydrate metabolism and structural support. Recently, scientists discovered that the extent of boron’s linking to a complex carbohydrate called RG-II in plant cell walls determines the size of the plant. The cross-linking involves covalent bonds between borate and cis-diols. Borate forms diester bonds with cis-diol compounds like those on RG-II and creates a net-like skeleton for the cell.

Mercury is well-known for being a toxin. The most toxic form of mercury is the organic mercury compound, methylmercury, or CH₃Hg. This compound induces neurological damage Mercury in the environment, both from natural sources as well as manmade sources such as contaminants released from the burning of fossil fuels, is converted into methylmercury by aquatic bacteria. Sulfur reducing bacteria (SRBs) are the primary creators of methylmercury. It is believed that they methylate mercury as a side reaction of the metabolism of sulfur in the form of HgS. The primary method of methylation is believed to be linked to the acetyl-CoA pathway; that CoDH catalyzes the binding of Hg to a methyl group. Factors that influence the methylation of mercury include pH (increase in pH corresponds to an increase in methylation), and, most importantly, sulfide concentration. The buildup of dissolved sulfide and a high sulfate concentration in the environment inhibit mercury methylation. The most common form of methylmercury in fish is CH₃HgCl(aq). This form is particularly toxic, because its hydrophobic properties allow it to cross cell membranes relatively easily. The methylmercury that the bacteria produce moves up the food chain when the bacteria are consumed or when they release methylmercury into the water to accumulate in plankton. The plankton, in turn, are consumed, and the methylmercury in them accumulates within their predators. Although methylmercury is easily absorbed, it is very difficult to eliminate. This results in a high accumulation of methylmercury in organisms at or near the top of the food chain, including fish and humans. Some bacteria produce the enzyme organomercurial lyase. This enzyme is capable of breaking the very stable mercury-carbon bond. Mercuric reductase detoxifies Hg²⁺ to produce volatile Hg.