Tag Archives: health

Mental Retardation and Dendritic Spines

spine

Dendrite is Greek for “tree-like” and to explain what they do in the simplest terms possible, they receive electrochemical signals from other neurons and then pass these signal down to the soma or neural cell body. Dendrites play a critical role in determining the frequency of the action potential, which drives the electrical signal down axons of the body of the neuron towards the axon terminals. Dendrites are so essential that their architecture is a great indicator of the complexity of our neural connections. In fact, our brain function depends on strong synaptic connections, connections which are cultivated during infancy and early childhood.

Unfortunately, as with all things complex, sometimes something goes wrong in the developing process. Mental retardation occurs when there is a disruption in this early refinement of dendrites that results in cognitive impairment severe enough to disrupt adaptive behaviour. There is a wide array of genetic disorders and poor environmental conditions that can result in mental retardation. For example, Down Syndrome and PKU (both genetic disorders), accidents during pregnancy and childbirth, maternal infections with rubella, Fetal Alcohol Syndrome and environmental impoverishment. Poor environmental conditions in young children such as poor nutrition, isolation and neglect can even result in brain damage severe enough to cause damage to these sensitive dendrites.

spine 2

Healthy dendrites have spines that look like small balloons that hang of the dendrite. In cases of mental retardation dendritic spines are very thin and long, resembling the dendritic spines of a fetus. This is clearly seen in the top most image, a) and c) are healthy dendrites. This clear difference reflects the failure of normal circuits in the brain’s development. Studies by Marin-Padilla and Purpura have discovered a correlation between extent of dendritic spine damage and degree of mental retardation.

Citations:

Bear, Mark F., Barry W. Connors, and Michael Paradiso. “Neurons and Glia.”Neuroscience: Exploring the Brain. Baltimore, MD: Lippincott Williams & Wilkins, 2006. 43. Print.

Images courtesy of google images.

 

Basic Nutrition: Essential Nutrients and Biosynthesis

Our bodies rely on food for energy but also for biosynthesis. Biosynthesis is the production of complex molecules within living organisms or cells; a process necessary for self-maintenance. For example, the synthesis of protein from neuropeptides. Two necessary precursors for biosynthesis are organic carbon (such as from sugar) and organic nitrogen (such as from amino acids). For a diet to be sufficient, therefore, it must supply chemical energy, organic molecules and finally essential nutrients.

For energy, animals ingest and digest nutrients such as carbohydrates, proteins and lipids to get enough ATP necessary for cellular respiration and energy storage. Essential nutrients are ingested as precursors to complex molecules and as minerals and vitamins. Unlike complex molecules, essential nutrients cannot be synthesised from raw materials. Thus, they must be ingested.

Amino Acids and Fatty Acids

Four types of essential nutrients exist: amino acids, fatty acids, vitamins and minerals. Approximately, half of the 20 amino acids are required for humans including: methionine, valine, threonine, phenylaline, leucine, isoleucine, tryptophan, lysine and histidine. Meat, fish, poultry, dairy products are considered complete proteins because they contain all essential amino acids. However, vegans and vegetarians or even meat-eaters can get all their essential amino acids by eating a full diet consisting of beans, legumes, nuts, seeds and vegetables. Insufficient amounts of amino acids causes protein deficiency, which can be severely detrimental to healthy development. Therefore, if you stop eating meat, it is important to make sure you are eating a diet that contains all your essential amino acids.

food1

Essential fatty acids are also required. Only two are known to be essential for human survival: alpha-linoleic acid and linoleic acid. Alpha-linoleic acid is a long-chain omega-3 fatty acid and is high in food such as salmon, tofu, shrimp, flax seeds and walnuts (fish, seeds, grains and vegetables). Linoleic acid is a long-chain omega-6 fatty acid and is found nuts, grains, cereals and poultry. Insufficient amounts of omega-3 and omega-6 contributes to impaired cellular functioning and heart disease.

Vitamins and Minerals 

The final two essential nutrients are vitamins and minerals. Vitamins come in two, organic forms: soluble and water-soluble. Fat-soluble vitamins are found in fatty foods such as animal products, vegetable oils, etc. They include vitamin A, D, E and K and are stored in our liver and fatty tissue. Deficiency in certain vitamins cause different issues (a future post will discuss this in more detail). Water-soluble vitamins, on the other hand, are not stored in the body and so need to be consumed more frequently. These means that when we urinate, these vitamins leave our body. Fortunately, that means it is hard to consume too many water-soluble vitamins. Too many fat-soluble vitamins can cause toxicity. Water-soluble vitamins include vitamin C, B and folic acid and can be found in foods such as fruit, vegetables (especially greens) and grains. As water-soluble vitamins are sensitive to heat and air, boiling can destroy the vitamins. Foods high in fat-soluble vitamins are far more durable.

Minerals on the other hand are inorganic and include calcium, iron, phosphorus, magnesium, sulphur, sodium, potassium and chloride. Minerals also come in two forms: macro or major minerals and trace elements. Macrominerals include electrolytes and the body stores about 5 grams of each one on hand. In order to stay healthy, a person to consume about 100mg a day to maintain the 5 gram store and equalise the loss. Trace elements are found in much smaller quantities, hence their name and include iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium and molybdenum. Minerals are essential because they serve as reinforcers for bone growth, strong teeth, maintaining homeostasis and synthesising energy from food. A great source of minerals is from plants such as fruits, vegetables and nuts as they get minerals directly from the soil they grow in. Grains, meats, cereals, dairy, etc. also contain minerals but in a diluted amount due to processing or because they have already been used by the animal itself.

All in all, a proper diet needs to incorporate all essential nutrients for proper health and functioning.

Bibliography

Campbell, N. A., & Reece, J. B. (2008). Animal Nutrition . Biology (8th ed., ). San Francisco: Pearson, Benjamin Cummings.

Rinzler, C. A. (2006). Nutrition for Dummies (4th ed.). Indianapolis, IN: Wiley Pub.

Vitamins and minerals . (2012, November 26). . Retrieved June 24, 2014, from http://www.nhs.uk/conditions/vitamins-minerals/Pages/vitamins-minerals.aspx

The Ebola Virus: What is it actually?

The Ebola Virus has been getting a lot of news coverage recently with a massive outbreak in West Africa. As of March this year the death toll is the highest of any Ebola outbreak ever recorded. The exact number is still increasing, but over one thousand individuals have been exposed with causalities now around 800 (Sender, 2014). Obviously this virus is deadly and scary, but what exactly is it? My family and I were discussing these outbreaks over dinner, and I thought that a great way to learn about it is to do some research.

ebola

History 

Firstly, the Ebola virus causes Ebola virus disease (EVD) or Ebola haemorrhagic fever (EHF) in humans. It is part of Genus Ebolavirus and the Filoviridae family. The Genus Ebolavirus consists of five distinct species:

  1. Zaire ebolavirus (EBOV)
  2. Bundibugyo ebolavirus (BDBV)
  3. Reston ebolavirus (RESTV)
  4. Taï Forest ebolavirus (TAFV)
  5. Sudan ebolavirus (SUDV)

Not all of these species are dangerous to humans. However, BDBV, EBOV and SUDV are all associated with mass outbreaks of EVD in Africa. Out of these three, EBOV is the most deadly. According to the World Health Organisation (World Health Organization, 2014) the RESTV species can infect humans, but they do not cause severe illness or death as is the case with the other three. Since 1994, EBOV and the TAFV species has infected chimpanzees and gorillas (WHO, 2014). Outbreaks of severe EVD have also been found in macaque monkeys in the Philippines in 1989, 1990 and 1996. Not only do outbreaks in non-human primates cause concern for them, but it also creates concern that one day EVD in humans can be brought on by the TAFV species.

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Map of outbreaks of the Ebola virus in Africa by strain and confirmed contractions. Distribution of Ebola Virus Outbreaks 1979-2008, South Africa Created by: Zach Orecchio University of South Florida Geography Dep. Data Source: http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebola/ebolamap.htm

EVD in humans first appear in 1976 in Western Africa. The virus occurred in two simultaneous outbreaks in two different villages, in Nzara, Sudan and Yambuku, Democratic Republic of Congo. The outbreak in the DRC fell along the Ebola River, hence the name.

Aetiology

As mentioned above, the Ebola virus is a virological taxon part of Genus Ebolavirus. The Ebola virus, as an a cellular virus, replicates through a host cell. The virus attaches itself to the host cell’s receptors through glycoproteins. Then it fuses its own viral membrane with the cell’s membrane. This fusion process allows the virus to release its nucleocapsid (which contains the virus’ genetic material) into the cytoplasm of the host cell. Using the cellular machinery of its host, the virus creates viral proteins and then as the protein levels rise, new nucleocapsids are also created (Noda et al. 2006). As the new genetic material rises in number, budding occurs. Budding is where the virus, creates an “envelope” using the host’s cell membrane. Essentially, creating a new virus from the host itself (ibid). Eventually, as more and more viruses are created from the host, the host will be destroyed.

Ultimately, the number of viruses in the body begins to wreak havoc. In humans and other primates, the virus eventually causes extreme hemorrhagic fever and in most cases, death.

Transmission 

Ebola is transmitted to humans through contact with infected bodily fluids (ie. blood, secretions). Contact can be direct through broken skin or mucous membranes or indirectly with environments contaminated with the fluids.The incubation period (2 to 21 days) means that people can get infected by a person that does not even know they are ill. It is natural that family and friends want to mourn their recently deceased loved ones; however, the mourning process can become a high risk activity. Often, the burial ceremonies involve direct contact with the deceased person before the virus has died. In other words, healthy individuals are being infected by their infected, deceased loved one (WHO, 2014). Other common ways Ebola is transmitted is through recovered individuals and working in the healthcare field. Any one that has sex with a man recovered from Ebola can become infected from their semen. The semen carries the Ebola virus up to seven weeks after recovery, hence the man will feel healthy, engage in sexual activity and unknowingly, infect others (WHO, 2014). Healthcare professions are at high risk when the proper sanitary precautions are not enforced or possible. Lastly, people that work with infected primates or pigs can also become infected with the disease; however, the likelihood lesser than contact with a diseased human. As stated above, not all viruses that have infected animals are capable of causing EVD in humans.

Currently there is debate that fruit bats, in particular genera Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata are natural hosts for Ebola. This hypothesis is based on an overlap between the EVD outbreaks and the geographic distribution of fruit bats in Africa.

Symptoms and Diagnostics

A major concern when treating Ebola is that it carries symptoms similar to many other diseases. According to the World Health Organization (2014) “malaria, typhoid fever, shigellosis, cholera, leptospirosis, plague, rickettsiosis, relapsing fever, meningitis, hepatitis and other viral hemorrhagic fevers” all need to be ruled out. Of course with equipment available in the Western world, this process is quite simple. Ebola can be precisely diagnosed by running a variety of diagnostic tests including but not limited to electron microscopy, antigen detection tests and virus isolation by cell culture (WHO, 2014). These diagnostic tools can rule out other disorders by checking for low white blood cell and platelet counts plus elevated liver enzymes (WHO, 2014).

In Africa, however, these diagnostic tools are not always available. Therefore, it is important that the symptoms are clearly laid out and understood. EVD causes “severe acute viral illness” with symptoms including headache, muscle pain, weakness, fever and sore throat. These initial symptoms then progress into vomiting, rash, diarrhea, reduced kidney and liver function and sometimes internal and/or external bleeding.

Treatment and Prevention 

Currently there is no vaccine for EVD despite many being tested. Those infected with EVD are being treated with various drug therapies, which are always being improved and remedied. Until a vaccine or a truly efficient treatment has been discovered, patients with EVD are being treated in intensive care where they are holistically cared for, keeping them hydrated through IV with an electrolyte solution.

As the mortality rate for Ebola is so high (as high as 90%) the best way to treat Ebola is to prevent it from happening in the first place (BMC, 2014). In other words, the best way to handle Ebola is to prevent it. For the general public this means educating them on how the disease is transmitted, teaching them proper sanitation procedures and providing them with ways to keep clean and safe such as making condoms and cleaning products readily available.

For more information do your own research or check out some of the websites in my bibliography.

Thank you for reading!

Emma

Bibliography 

Assembly and Budding of Ebolavirus. (n.d.). Retrieved August 6, 2014, from

Ebola virus. (2014, May 8). Retrieved August 6, 2014, from http://en.wikipedia.org/wiki/Ebola_virus

Ebola Virus. (2014, August 4). Retrieved August 6, 2014, from http://www.cdc.gov/vhf/ebola/

Ebola Virus. (2014, June 17). Retrieved August 6, 2014, from https://www.bcm.edu/departments/molecular-virology-and-microbiology/ebola

Ebola virus disease. (2014, April 8). Retrieved August 6, 2014, from http://en.wikipedia.org/wiki/Ebola_virus_disease

Ebola virus disease. (2014, April 1). Retrieved August 1, 2014, from http://www.who.int/mediacentre/factsheets/fs103/en

Ebola virus disease. (2014, January 1). Retrieved August 6, 2014, from http://www.who.int/mediacentre/factsheets/fs103/en/

Noda, T., Ebihara, H., Muramoto, Y., Fujii, K., Takada, A., Sagara, H., … Kawaoka, Y. (2006, September 29). Assembly and Budding of Ebolavirus. Retrieved August 6, 2014, from Noda, T., Ebihara, H., Muramoto, Y., Fujii, K., Takada, A., Sagara, H., … Kawaoka, Y. (n.d.). Assembly and Budding of Ebolavirus. Retrieved August 6, 2014.

Sender, H. (2014, July 31). Where Is The Ebola Virus? Outbreak Map Shows Virus Deaths In West Africa. Retrieved August 6, 2014, from http://www.ibtimes.com/where-ebola-virus-outbreak-map-shows-virus-deaths-west-africa-1645012