«Prior to delineating the organization of specific intraneuronal signaling pathways, it is important to consider, in general terms, their role in helping neurons interpret and respond to the barrage of afferent stimulation impinging on them...» Document abstract
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biology
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26/11/2007
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SummaryPrior to delineating the organization of specific intraneuronal signaling pathways, it is important to consider, in general terms, their role in helping neurons interpret and respond to the barrage of afferent stimulation impinging on them continuously. From an evolutionary perspective, second messenger systems predate neurotransmitters and neurotrophins, examples of first messengers detected by cell surface receptors. Before the advent of neurotransmitters, prokaryotic organisms relied on cyclic adenosine monophosphate (cAMP) and other intracellular signaling pathways to coordinate diverse responses located in disparate parts of these unicellular organisms to changes in ambient nutrients or conditions. Neurotransmitters and neurotrophins have evolved subsequently to take advantage of these internal signaling pathways that have undergone a parallel growth process.
Table of Contents
- Intraneuronal signaling pathways do more than merely enlarge the sphere of influence of afferent stimuli beyond the local environment of the cell surface receptor.
- Although the overwhelming majority of psychiatric drugs target extracellular receptors or uptake sites, the explosion of information on intraneuronal signaling pathways suggests that these may represent suitable drug targets.
- Psychiatrists have long been taught that a true understanding of normal and abnormal behavior requires an appreciation of the interplay of forces lurking beneath the surface.
- Neurotransmitter receptors may couple to adenylate cyclase via different classes of G proteins, referred to as Gs or Gi, depending on whether they stimulate or inhibit cyclic AMP formation.
- Cyclic GMP Besides cyclic AMP, another cyclic nucleotide, cyclic guanosine monophosphate (GMP) has been identified as a second messenger regulated by neurotransmitter receptor stimulation.
- Because the effects of cAMP are mediated to a large extent via activation of a kinase, it was generally assumed that each of these second messengers acted in a similar fashion.
- However, this view has been challenged recently in light of animal studies demonstrating that inositol levels in brain are unaffected by lithium concentrations within its therapeutic range.
- These alternate arrangements emphasize the notion that intracellular signaling cascades have evolved in ways that heighten their versatility, with each of the components having multiple signaling capacities.
- Another family of tyrosine kinases has been identified that differs from the receptor tyrosine kinases in that it contains only the cytoplasmic domain.
- Cross-Talk Among Signaling Pathways The organization of intraneuronal signaling pathways allows for a high degree of interaction or cross-talk among pathways
An Assessment of Historical and Contemporary Land Use at Hedgehog Mountain, Freeport, Maine, via Field Observation
«The purpose of this investigation was to collect information that allowed the formulation of a hypothesis as to the land-use history of the Hedgehog Mountain preserve, and to correlate empirical observations with a limited literature review in an...» Document abstract
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biology
case study
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SummaryThe purpose of this investigation was to collect information that allowed the formulation of a hypothesis as to the land-use history of the Hedgehog Mountain preserve, and to correlate empirical observations with a limited literature review in an attempt to validate the hypothesis presented.
The author hypothesizes that this land was used primarily for grazing livestock and timber extraction until the homestead was abandoned, after which timber harvesting may have continued for a number of decades. Except for motorized recreational vehicle use the land is presumed to have been free of major human disturbance for the past fifty years or more.
The author hypothesizes that this land was used primarily for grazing livestock and timber extraction until the homestead was abandoned, after which timber harvesting may have continued for a number of decades. Except for motorized recreational vehicle use the land is presumed to have been free of major human disturbance for the past fifty years or more.
Table of Contents
- INTRODUCTION:
- METHODS:
- RESULTS:
- Hydrology:
- Disturbance History:
- DISCUSSION:
«The term pit viper comes from the presence of paired, highly sensitive, thermoreceptor organs (pits) present on the forward portion of these snakes' heads. These structures, also known as foveal organs, serve the snake in locating prey, aiming...» Document abstract
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SummaryThe term pit viper comes from the presence of paired, highly sensitive, thermoreceptor organs (pits) present on the forward portion of these snakes' heads. These structures, also known as foveal organs, serve the snake in locating prey, aiming strikes, and adjusting venom dose. The foveal organs can detect temperature changes of as little as 0.003° C (0.0054° F). A neurologic feedback loop between the foveal organs and the venom delivery apparatus may allow the snake to adjust the volume of venom it injects into a potential meal or a perceived threat.
Table of Contents
- Anatomy
- Pit Vipers.
- Coral Snakes.
- Venoms
- Pit viper venom has both offensive (i.e., food gathering) and defensive functions.
- A popular belief is that juvenile rattlesnakes are more dangerous than adult snakes because their venom is more toxic and they are unable to control the volume they release.
- Neurotoxicity has been clinically associated with severe myotoxicity in many cases.
- Mojave toxin is thought to inhibit acetylcholine release at the presynaptic terminal of the neuromuscular junction.
«The two venomous lizards of the world are impressive creatures about which much misinformation has been spread for centuries. They have been thought to possess supernatural features such as poisonous breath, a stinging tail and the ability to spit...» Document abstract
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biology
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SummaryThe two venomous lizards of the world are impressive creatures about which much misinformation has been spread for centuries. They have been thought to possess supernatural features such as poisonous breath, a stinging tail and the ability to spit their venom. The Gila monster (Heloderma suspectum) reaches a maximum length of approximately 50 cm, whereas the beaded lizard (Heloderma horridum) is larger, reaching almost a meter. They are both heavily built and possess massive muscles of mastication with powerful biting capacity. The venom delivery apparatus consists of a pair of anterior, multilobed, interior labial glands that open through a series of ducts into the labial mucosa. Their teeth are lancet shaped, grooved, and loosely attached to the jaws. When the reptile becomes agitated, it salivates heavily, producing a flow of venom into the labial mucosa. It bites with a powerful, chewing motion, instilling venom into the wounds by capillary action along the grooves of the teeth. Teeth may be left in the wounds, especially if the lizard must be forcefully removed from the victim. The tenacious creature may still be attached when help arrives. Effective envenomation occurs in only about 70% of bites.
Table of Contents
- Anatomy
- Venom
- Clinical Presentation
- Management
- Prehospital Care.
- Hospital Care.
- Morbidity and Mortality
«Genetic mutations are not uncommon. They can happen for a variety of reasons and have a variety of effects. Those with negative effects are weeded out by natural selection, and those with positive effects prevail and are accumulated due to natural...» Document abstract
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biology
school essay
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27/11/2007
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SummaryGenetic mutations are not uncommon. They can happen for a variety of reasons and have a variety of effects. Those with negative effects are weeded out by natural selection, and those with positive effects prevail and are accumulated due to natural selection. These mutations can be caused by a variety of reasons such as copying errors during cell division, exposure to ultraviolet rays and viruses, or can happen deliberately (Wikipedia). Most mutations have no effect on a species or its individuals because DNA repair is quite successful in fixing most mistakes before they become permanent. But there are very few mutations which have beneficial consequences. One such mutation that results in benefits for a species/individuals that make it up, is the CCR5-Delta32 mutation. During this mutation the Delta32 base pair is deleted in human CCR5 which results in immunity to HIV Type 1 (if homozygous) or increased resistance to AIDS (if heterozygous) (Wikipedia). The very controversial current argument on this subject asks several questions: if the absence of the CCR5-Delta32 is ultimately beneficial to humans, or if its negative side effects outweigh the benefits; as well as, where the origins of this mutation are.
Table of Contents
- The CCR5-Delta32 mutation is quite a recent discovery which is highly debated and still very circumstantial.
- There is also another possibility that this mutation is much older and has resulted due to smallpox outbreaks in Europe, which is the less popular theory.
- Along with protecting against HIV, the allele also protects against smallpox and the plague.
- Many aspects of CCR5-Delta32 are highly controversial. Its origins alone have split the scientific community.
- The basic question asks which is more beneficial: the absence of the CCR5 receptor or its existence?
«When Albert Hofmann created LSD 25 during experimentation in his laboratory, he had no idea what was to become of it, or what kind of an impact it would have. "Dr. Humphry Osmond invented the term 'psychodelic', which was later amended to...» Document abstract
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biology
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27/11/2007
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SummaryWhen Albert Hofmann created LSD 25 during experimentation in his laboratory, he had no idea what was to become of it, or what kind of an impact it would have. "Dr. Humphry Osmond invented the term 'psychodelic', which was later amended to 'psychedelic to get rid of the nuthouse connotation of 'psycho'." (Wolfe 39). This term encompasses a whole generation, a cultural revolution that took place during the 60's. Since its creation, LSD, among other psychedelics, has had a great impact on the American culture.
Table of Contents
- Albert Hofmann was the chemist who created LSD 25 (lysergic acid diethylamide) in his laboratory in Sandoz Pharmaceutical Laboratories in Basil, Switzerland in 1938.
- Dr. Werner Stoll, the son of Sandoz president Arthur Stoll and a colleague of Albert Hofmann's, was the first person to investigate the psychological properties of LSD
- The government, especially the CIA, became deeply involve in research and testing of psychedelic drugs
- The CIA tested acid on unwitting American citizens, volunteers, and themselves. Results were inconsistent.
- Leary was given a 10 year jail sentence in 1970 for possession of less than a half ounce of marijuana (Brown "Mavericks...").
- Kesey's place in La Honda became a center for the emerging counterculture. People dropped in whenever they felt like it.
- LSD has been found by many to cause profound changes in the mental state.
- He compared the brain to a reducing valve something that closes the Doors of Perception and lets in only the information that is need.
- We must not forget visual art, for that was also very affected by the discovery of LSD.
- The whole psychedelic scene calmed down after the sixties, but never quite stopped.
«In this study the Brassica Rapa will be tested to see if salt water effects it's growth. Data will be
taken from four different types of groups: distilled water; 0.25% of sodium chloride; 1.00% of sodium
chloride; and 4.00% of sodium chloride....» Document abstract
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biology
school essay
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SummaryIn this study the Brassica Rapa will be tested to see if salt water effects it's growth. Data will be
taken from four different types of groups: distilled water; 0.25% of sodium chloride; 1.00% of sodium
chloride; and 4.00% of sodium chloride. Data will be collected in a twenty-two day span, every other
day, to document changes in growth and appearance.
The Brassica Rapa, well known as the tulip, cabbage, and spinach has an unknown origin but is
suggested to be from the Eastern Mediterranean to Pakistan and Eastern China (www.prota.org). In the
time of Alexander the Great (356 – 323 B.C.) the turnip was described throughly which implies that
around his time the Brassica Rapa spread from the Middle East and Persia down to south-eastern Asia
and Africa via trade routs (www.prota.org). Today, species of the Brassica Rapa are found world-wide,
with documents of coming to America in the 1500's (FloriData, Home Greenhouse Kits).
«Finding the effects of salt on germination and growth of plants took twenty-two days of
research. Each collection day the height, height of the leaf, color, height of the node, number of buds,
and the number of the flowers were taken into account....» Document abstract
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biology
school essay
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SummaryFinding the effects of salt on germination and growth of plants took twenty-two days of
research. Each collection day the height, height of the leaf, color, height of the node, number of buds,
and the number of the flowers were taken into account. Based on the original hypothesis stating that the 4.00 % of sodium chloride will not develop well and will most likely die was correct. Throughout the procedures the control group displayed the maximum of values each section should experience. Although the original experiment was destroyed after collection day six, data from other groups proved the hypothesis to be correct and carried on where the plants left off.
«This report examined the effects of road salt in relation to growth and germination in the
Brassica rapa, a common turnup flower. The initial questions considered if the salt would actually
affect the growth. There were four groups of plants which...» Document abstract
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biology
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SummaryThis report examined the effects of road salt in relation to growth and germination in the
Brassica rapa, a common turnup flower. The initial questions considered if the salt would actually
affect the growth. There were four groups of plants which were collected. The groups included a
control (0.00% sodium chloride), 0.25% sodium chloride, 1.00% sodium chloride, and 4.00% sodium
chloride. Data was collected from the length of the plant, color, length of nodes and number of flowers.
The experiment showed that sodium chloride (road salt) does in fact affect growth and germination in
plants.
«From the beginning of the ideas presented by Charles Darwin in The Origin of Species, and their gaining support from the scientific community, the theory of evolution was been met with opposition. A great deal of this opposition came from religious...» Document abstract
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biology
school essay
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SummaryFrom the beginning of the ideas presented by Charles Darwin in The Origin of Species, and their gaining support from the scientific community, the theory of evolution was been met with opposition. A great deal of this opposition came from religious groups who believed in a creation from a divine being. Perhaps the strongest defense for the possibility of divine creation came from the ideas of William Paley’s Argument from Design. Darwin, who came after Paley, proposed that it was not any sort of Intelligent Design from a creator that led to people and other organisms having various functions, but natural selection. Darwin went on to specifically refute some of Paley’s examples, such as the vertebrate eye. When looking at Darwin’s theories and explanations, it is nearly impossible to believe that his work did not refute the work of Paley.
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