Friday, 26 February 2016

Cystic Fibrosis

Cystic fibrosis is a genetic condition where the lungs and digestive system are clogged by mucus. It is the second most life-shortening inherited disorder in the United  States, proving its seriousness. The symptoms include persistent coughing, recurring lung infections and poor weight gain.


Cystic fibrosis can be identified by screening new-borns. By taking a small blood sample from the baby's heel, eight other conditions as well as cystic fibrosis can be identified. For adults, a pregnant woman can certify whether their developing foetus has the faulty gene by passing a fine needle into the womb. This action, known as antenatal testing, is carried out if the condition is common in the mother's ancestry. A piece of developing placenta is removed to examine its chromosomes.
New-born screening
The Chloride Channel
For a quicker diagnosis, by tasting the sweat of a baby, saltiness would indicate cystic fibrosis. This is due to a defect in the CFTR gene, which not only causes cystic fibrosis, but is used to synthesise the protein (cystic fibrosis transmembrane conductance regulator) involved in the movement of salt in cells. Defective CFTR triggers poorly synthesised genes, causing mucus to form and very salty sweat. This is due the chloride channel being altered in stability and structure, preventing transport of chloride ions and therefore water into and out of cells.  The build up of these ions causes the cells lining the lungs and other organs to form mucus.

The CFTR defect is recessive, therefore if both parents are carriers, there is a 25 per cent chance that the child will inherit the condition.

Diagram of CF inheritance
(National Institute of Health, 2017)
Recurring lung infections are also suffered by cystic fibrosis sufferers. Often due to the mucus build-up, as it provides ideal conditions for bacterial habitation. Treatment with antibiotics raises the issue of resistant bacteria developing and as a result contact between sufferers, since they are the most vulnerable, must be kept at a minimal.

As well as the mucus lining the lungs, it can also line the organs involved in the digestive system. If the pancreas ducts are blocked, pancreatic insufficiency can occur. This means that it cannot perform its endocrine functions, including the secretion of essential enzymes needed for digestion. Therefore, often sufferers are unable to absorb the nutrients and metabolize them properly, leading to malnutrition.

Unfortunately, there is no cure for the condition. Sufferers can be treated with antibiotics to fight lung infections, and increase immunity through flu jabs . To thin down the mucus, the enzyme Pulmozyme is issued, which breaks down the mucus so that it can then be coughed up. A strict diet consisting of high calorie foods, rich in fat and protein, must be followed as well to prevent malnutrition. Capsules containing essential enzymes are also taken to help digestion if the pancreas is inert due to mucus build up. Those with breathing problems may also use bronchodilators, a form of gaseous medication which helps keep the airways open by relaxing the muscles around the bronchial tubes.
References:
nhsuk(2016). wwwnhsukRetrieved 26 February, 2016, from http://www.nhs.uk/Conditions/cystic-fibrosis/Pages/Introduction.aspx

Webmdcom(2016)WebMDRetrieved 26 February, 2016, from http://www.webmd.com/lung/what-is-cystic-fibrosis

Cfmedicinecom(2016)CfmedicinecomRetrieved 26 February, 2016, from http://www.cfmedicine.com/htmldocs/CFText/basicproblem.htm

Saturday, 20 February 2016

Hydrocephalus

Hydrocephalus is a condition caused by an abnormal build up of fluid in the brain’s ventricles or cavities. Although in 2015, 400,000 newborns were born with this condition, treatment of hydrocephalus is still lacking, particularly in developing countries. In Uganda, neurosurgeons number 1:10,000,000 showing the urgency for more qualified staff. In the past, the fluid was thought to have been water, hence the term ‘hydro’. Now the fluid has been identified to be cerebrospinal fluid (CSF), a clear liquid that surrounds the brain and spinal cord.
Baby with hydrocephalus

The main purposes of CSF are to keep the brain tissue buoyant, act as a transport medium, and to compensate for the changes in intracranial blood volume (the amount of blood within the brain). Every day, the brain produces half a litre of CSF a day, with the old fluid being released from the brain to be absorbed by blood vessels. If this process were to be interrupted, the ventricles would be forced to enlarge in order to accumulate the large volumes of CSF, resulting in greater pressure on the brain.

There are two ways of developing hydrocephalus: congenitally or acquired. Congenital hydrocephalus is present at birth. It can occur due to abnormal foetal development or genetic abnormalities. Most often, these abnormalities are bleeding in the foetus during development or as a result of certain infections from the mother, such as syphilis.

Acquired Hydrocephalus occurs at birth or after. This could be from physical injury such as a head trauma. It is then identified as Normal Pressure Hydrocephalus (NPH), occurring often in those over the age of 60.

The physical symptoms of hydrocephalus can be easily identified, as the condition causes a baby’s head to grow at an abnormal rate. Fibrous material between the five bone plates allow the head to grow after birth. However with hydrocephalus, these sutures become abnormally large and the frontanelles (the area where sutures meet) bulge due to pressure from the build-up of CSF.  


This pressure can cause significant brain damage, triggering mental problems. The classic triad for NPH consists of an abnormal gait, urinary incontinence, and dementia. This is due to NPH affecting the parts of the brain controlling the legs, bladder, and the "cognitive" mental processes like memory. Since this classic triad of symptoms are similar to those of Parkinson’s disease and Alzheimer’s, NPH is often misdiagnosed. Normal pressure hydrocephalus can be accurately identified through neurological examinations, commonly CT scans. The images produced can aid doctors and surgeons when performing shunt surgery, which has failure rates ranging from 40 to 50%.

Shunt surgery can only treat not cure NPH. During this procedure, a neurosurgeon would implant a long tube with a valve into the ventricle of the brain, to drain away excess CSF. Increase in pressure would cause the valve to open, releasing the fluid through the tube and allowing it to flow in one direction only. The tube leads into the peritoneal cavity, where CSF can be absorbed safely into the bloodstream, preventing any build up of CSF in the brain.

References:
nhsuk(2016). wwwnhsukRetrieved 10 February, 2016, from http://www.nhs.uk/conditions/Hydrocephalus/Pages/Introduction.aspx

Mediamaker(2016)HeadwayorgukRetrieved 10 February, 2016, from https://www.headway.org.uk/about-brain-injury/individuals/types-of-brain-injury/hydrocephalus/

Healthlinecom(2016)HealthlineRetrieved 10 February, 2016, from http://www.healthline.com/health/hydrocephalus

Hydroassocorg(2016)HydroassocorgRetrieved 10 February, 2016, from http://www.hydroassoc.org/about-us/newsroom/facts-and-stats-2/

Wednesday, 17 February 2016

Axolotls: The Secret to Regeneration

Regeneration is one of the ultimate abilities that humans lack, however the axolotl native to Lake Xochimilco in Mexico has cracked this long searched for secret. 

An axolotl
They have recently become infamous for their bizarre smile, but more importantly in the scientific world, their perfect display of regeneration and neoteny. This is where instead of developing until the peak of adult form, axolotls maintain their juvenile characteristics such as retaining external gills and lidless eyes. Therefore aging is of little concern and so is the fear of losing a limb or two as all complex anatomical structures can be grown in a period of months.
Example of neoteny in apes

Scientists have tested the axolotls’ miraculous regeneration by amputating their limbs and discovering that ‘’they can regenerate the same limb 50, 60, 100 times. And every time: perfect." 

Axolotl's regenerative abilities
The cells at the site of amputation become pluripotent, this is the ability to differentiate, similar to embryonic stem cells. A blastema forms on the wound as a clustered mass of the pluripotent cells which finally develop into a fully functional limb. Scientists at the University of Montreal have discovered that the levels of the protein TGF-β1 in particular increase during the formation of the blastema, and when inhibited, little regeneration development is displayed. Similarly, p53 showed to also be essential in the axolotls’ regenerative pathway. 

Fortunately, a connection has been made between humans and the axolotl, with both species sharing the compounds p53 and TGF-β1.

Currently, scientists are still distant from successfully transferring the relationship between the two proteins to humans in order to share the regenerative abilities of the axolotl. However, the salamander has introduced a hope in the scientific world that the possibility of becoming fully dependable on our own regenerative abilities will no longer be a secret.

References:
David manly(2011, )Regeneration: The axolotl story[Weblog]Retrieved 04 February, 2016, from https://blogs.scientificamerican.com/guest-blog/regeneration-the-axolotl-story/

Tanya lewis(2013)Missing Parts? Salamander Regeneration Secret RevealedRetrieved 04 February, 2016, from http://www.livescience.com/34513-how-salamanders-regenerate-lost-limbs.html

Ambystomaorg(2016)AmbystomaorgRetrieved 04 February, 2016, from http://www.ambystoma.org/education/80-how-long-does-it-take-for-a-salamander-to-regenerate-a-limb

Axolotlorg. (2016). Axolotlorg. Retrieved 04 February, 2016, from http://www.axolotl.org/