Wikipost #1 (Genetics): Turner Syndrome

The Condition

A diagram showing the symptoms and common traits of someone with Turner syndrome.
A diagram showing the symptoms and common traits of someone with Turner syndrome.

Turner Syndrome is a chromosomal condition that affects 1 in 2,500 females and up to 10% of miscarriages. It is developed in zygotes when one of the two gender-determining X chromosomes is either incomplete or missing altogether. And in 75 to 80% of known cases the missing or incomplete chromosome comes from the father. In rare cases, the female has both X chromosomes in some cells, but only one chromosome in the rest of her somatic cells; this is known as mosiacism. Turner Syndrome was discovered in the 1930's by Dr. Henry Turner while he was the Assistant Professor of Medicine at the University College of Medicine.




The Cause
A diagram illustrating the process of nondisjunction and it's affect on resulting daughter cells.
A diagram illustrating the process of nondisjunction and it's affect on resulting daughter cells.

The most common cause of Turner Syndrome is nondisjunction during meiosis. Nondisjunction is defined as, “The failure of homologous chromosomes to segregate or to separate during and after meiosis;” this leads to an imbalance of chromosomes in the daughter sex cells. This is problematic because when the sperm and egg meet there will be too many chromosomes (this often leads to conditions like Down Syndrome) or not enough chromosomes. If the gender chromosome the father delivered was an incomplete Y chromosome, the resulting embryo would not develop past three or four divisions. But if the father delivers an incomplete X chromosome, the embryo will develop – albeit slowly and less-so than an embryo with a full chromatic set – and in the case that the father does not deliver an X chromosome at all, the mother's genetic information will perform somewhat of an override, and the resulting child will be female.
The DNA sequencing of a patient with Turner syndrome
The DNA sequencing of a patient with Turner syndrome



The syndrome is diagnosed in one of two ways. Tests can be done while the fetus is still in utero and once the child has been born. When the baby is still inside it's mother ultrasounds can be used to identify the characteristic stunted growth and other symptoms of the syndrome. Doctors can also use chorionic villus sampling, where a sample of the placenta is removed for testing, or amniocentesis, where a sample of the amniotic fluid surrounding the baby is sampled for testing. A diagnosis can also be reached after birth if the doctor catches the symptoms, or later in life – during puberty to be exact – if the girl fails to grow normally or undergo puberty at all.


The Symptoms
The most telling symptom of a girl with Turner syndrome is height. The average height reached by girls who possess the syndrome is 4'8'' if they choose not to use human growth hormone to increase their physical growth. Those who do take the hormone have been known to reach more average heights. Another symptom common among those with Turner syndrome is ovarian failure, which leads to the inability to produce eggs or female hormones. Estrogen is often supplemented to help patients achieve breast growth (1/3 do not need the hormone to help with this), “feminine” curves, menstruation and proper body development. Other symptoms that are not all-inclusive are: webbed neck, hands and feet, scoliosis, flat feet, frequent ear infections, heart murmurs, the tendency towards high blood pressure later in life, osteoporosis, kidney abnormalities, thyroid problems, and a heightened risk to develop celiac disease.


Treatment
The structure of Estrogen, the hormone most comely used to treat those with Turner syndrome.
The structure of Estrogen, the hormone most comely used to treat those with Turner syndrome.

There is no finite cause for Turner syndrome, but there are steps and treatments that can be taken to minimize the symptoms. Hormone treatments are the most common treatment; human growth hormone can supplement growth and estrogen can help the body progress through puberty. Most girls with Turner syndrome will undergo some form of hormone therapy at some point in their life, mainly during adolescence. And specialized doctors are a necessity as well. Cardiologists can assist with heart problems, orthopaedic paediatricians deal with bone issues like scoliosis and lack of bone buildup, and kidney specialists can assist with abnormalities in their field.




Further Reading
Article about mother wanting to raise awareness of Turner syndrome:
http://www.valleynewslive.com/story/24648259/while-its-rare-local-mom-wants-you-to-be-aware-of-turner-syndrome


Article about 20 year old with Turner syndrome who wants to raise awareness:
http://www.wdio.com/article/stories/s3301046.shtml


A girl's blog detailing her life with Turner syndrome:
http://colleenmjoyce.blogspot.ca


Article about parents fundraiser to honour their daughter with Turner syndrome: http://www.statesboroherald.com/section/1/article/56968/


References

http://www.medicinenet.com/turner_syndrome/page2.htm
http://www.genome.gov/19519119
http://www.turnersyndrome.ca/turnerssyndrome.html
http://learn.genetics.utah.edu/content/disorders/chromosomal/turner/
http://www.turnersyndrome.org/learn-about-ts/fact-sheet
http://www.biology-online.org/dictionary/Nondisjunction
http://www.babycenter.ca/a328/chorionic-villus-sampling-cvs
http://www.babycenter.ca/a327/amniocentesis




Wikipost #2 (Evolution): The Evolution of the Yorkshire Terrier

A typical Yorkie with a puppy coat
A typical Yorkie with a puppy coat
An Introduction

Yorkshire terriers are often considered "snooty" dogs. They weigh in under 7 pounds, are generally shorter than 9 inches, and are globally considereda toy breed. Yorkies are well-known for their characteristic long coat (although may pet owners prefer to keep ashorter "puppy coat" to make things easier), which extends to the floor, and their coloration of dark black with present tan patches. With a lifespan of 12-15 years, they are given plenty of time to develop the confident, aloof air which is desirable in breeders.Yorkiesare generally acknowledged as intelligent toy types, despite the show stereotype of snootiness. But Yorkies are popular family dogs as well, registered as the third most popular breed owned by dog owners with the American Kennel Club. ButYorkies did not start out as lap dogs. Their origin story is much less glamorous, and a lot dirtier.

Breed Background

A hybrid of the now extinct Clydesdale Terrier and the ever-present Scottish terrier, the dog first appeared in Yorkshire, a county in Northern England. The small breed (larger than today's, however) was attractive to working class citizens for two reasons. Firstly, Yorkshire terriers were easily portable in case of moving, which was convenient when people moved around to find work. And secondly, more importantly, Yorkies were the perfect size to catch rats. They were useful in large cities, where rodent infestation was a huge problem. Yorkies, with their surprising speed, could easily chase rats through alleys, and some were small enough to follow the rats home, effectively killing them. Yorkies also made great companionship for the working class. They often travelled to work with their owners, whether that was in a mine or in a shop. They soon became valued for their loyal behaviour, and gained a reputation as good workers and good pets.
A Victorian lady and her Yorkie
A Victorian lady and her Yorkie

Yorkshire Terriers in America and Dog Shows

Yorkshire Terriers were introduced to American in 1872, with the breed beginning to slowly spread in popularity. The American Kennel Club noted the first Yorkie's registration was in 1885, and the breed's notoriety grew exponentially. As America began to put on dog shows, Yorkies became popular contestants, a far cry from their ratting roots. However, the breed was not suited for dog shows. They could not compete against the sheer size of the working category, and the judges much preferred other toy breeds. The first Yorkie to ever win a major dog show was Ozmillion Mystification (a questionable dog name) at Cruft's in 1997. While Yorkies rarely win competitions, they remain a highlight of the show for many lovers of the breed.


external image 66155-300x199-Yorkie_show_dog_1.jpg


Diseases in Yorkies

Like many small breeds, Yorkies have a predisposition to many diseases. This is largely the fault of the pure breeding and show breeding communities. Yorkies have been bred to be smaller and smaller, with weights of under four pounds become desirable. The most prevalent diseases in Yorkshire terriers are bronchitis (inflammation of the bronchial tubes), portosystemic shunt (liver problems), cataracts (eye problems), keretis sicca (eye dryness) and lymphangiectasia (intestinal problems).Yorkies are also likely to experience dental problems, such as tartar buildup and gingivitis. Genetic disorders are common in Yorkshire terriers, such as: distichiae, where eyelashes grow from other spots than the eyelid, Legg-Calve-Perthes syndrome, which causes femur degeneration, luxating patellas, also known as slipping kneecaps, and tracheal collapse, where the trachea will collapse, often killing the dog. Many disorders can be treated so the dog can be saved, although some pet owners would prefer not to see their dog suffer.


An example of poor Yorkie dental health
An example of poor Yorkie dental health









A video depicting one of the smallest Yorkshire Terriers alive.



Further Reading
Article about Coyote Snatching Yorkie in front of Family
Article About Genetic Disorders in Small Dogs- including Yorkies
Story of Smoky, a WWII Yorkie
Canadian Kennel Club Breed Standards

References


http://susanbailey.articlealley.com/the-evolution-of-the-yorkshire-terrier-461160.html
http://www.vhfulop.com/Estandard.htm
http://www.breedia.com/dogs/yorkshire-terrier
http://www.caranealyorkshireterriers.com/our-breed/yorkshire-terriers-breed-history.html
Wikipost #3 (Human Systems): Neurological Diseases

a human brain
a human brain
Introduction


The brain is the control centre of the human body, this much is completely clear. Through using it's hundreds of billions of neurons, it sends impulses all throughout the human body to control daily processes. The organ controls blood pressure, body temperature and other internal balances; the brain processes all sensory information to respond to external and internal stimuli in a timely, appropriate manner. The brain is responsible for humans being able to survive another day. And the specification of various brain parts means that many have individual control over individual body parts. But what happens when the brain falls victims to disease? What happens when various parts lose connection or stop working altogether?




The Structure of the Brain
The brain as a whole, in study, is classified into three parts. First there is the forebrain, often interpreted to be the whole brain, which houses the cerebrum, cerebellum and the limbic system. The cerebrum is
A diagram depicting the four lobes
A diagram depicting the four lobes

broken into four lobes: the frontal (reasoning, planning, speech), the parietal (movement, orientation, recognition and perception), occipital (visual processing), and temporal (perception, recognition of
auditory stimuli, memory and parts of speech). The cerebrum is very wrinkled, and the folds allow for more connections to form between neurons, so the brain can function at a higher capacity. The cerebellum, referred to as the little brain, covered by the cerebrum, coordinates movement and balance. The third part of the forebrain is the limbic system, known as the emotional brain, houses various endocrine glands and controls emotional responses to outer stimuli. Moving to the midbrain we find the tectum and tegmentum; these parts control vision, hearing, movement of the eyes, and the movement of the body. Finally the hindbrain is made of the pons and medulla. The pons, which is linked to the cerebellum, affects movement, posture, consciousness, motor control and analysis of sensory stimuli. The medulla, part of the brain stem, performs the important task of regulating the heart and breathing rates of the human body. The brain is a complex organ, and an understanding of this complexity gives us the foundation to understand how devastating brain diseases can be.

Epilepsy and the Brain

One of the most well-known neurological conditions is epilepsy. The fourth most-common brain disorder, epilepsy is characterized by it's symptom of seizures in those who possess it. It is a chronic disorder, and while 50-60% of those affected have no definite cause, it is assumed by scientists that there are reasons to agitate the likelihood of epileptic behaviour: brain tumours, strokes, head trauma, injury and infection of a mother while in utero, an blunt trauma as an infant, aftermath of an infection, and alcoholism. The electrical impulses that trigger an epileptic seizure are known to happen in variant parts of the brain, so it is hard to pin down a specific structure that is the most affected. The most common treatment for those who suffer from epilepsy is long-term drug therapy and phsyical therapy.


The difference in blood flow between a non-affected brain and an affected brain
The difference in blood flow between a non-affected brain and an affected brain



Alzheimer's and the Brain

Alzheimer's disease is a degenerative, fatal disease that is the most common form of dementia (60-80% of cases) in modern times. While many forms of dementai can be treated or held off, Alzheimer's has no known cure and is always fatal, making it both saddening and scary at the same time. The disease begins it's tirade by clumping in the parts of the brain responsible for memory and learning, and forms tangles between the neurons to prevent information and signals from being passed along. These and almyloid plaques prevent information from circulating through the brain as it normally would. These also inhibit brain function and aid in the spreading of the disease throughout the nervous system's control centre. The tangles are the likely suspect of the high rates of brain cell death, a key to Alzheimer's. As the disease progresses, more and more cells die off and the number of neurotransmitters drastically decrease. Alzheimer's often presents itself in the symptoms of memory loss, confusion, constant mood swings, depression, loss of balance, and loss of fine and gross motor skills.


The difference between a healthy brain and Alzheimer's ravaged brain
The difference between a healthy brain and Alzheimer's ravaged brain





A Ted-Ed Video Detailing Alzheimer's

Further Reading

Article About Failure to Medicate Epileptic Teens Causing Depression Rates to Increase

A Personal Account on Living with Epilepsy

Details on Study of Aging Brains and How to Protect Against Alzheimers'

Information about Likelihood of Alzheimer's Study

References

http://www.epilepsy.ca/en-CA/Facts/Epilepsy-Facts.html

http://www.epilepsy.com/learn/epilepsy-101/what-epilepsy

http://www.epilepsy.com/learn/epilepsy-101/what-epilepsy

http://science.howstuffworks.com/life/inside-the-mind/human-brain/brain.htm

http://www.webmd.com/brain/picture-of-the-brain

http://health.howstuffworks.com/mental-health/neurological-conditions/alzheimers3.htm