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Amyloidosis

Alternative Names: Amyloid – primary

Definition:
In medicine, amyloidosis refers to a variety of conditions in which amyloid proteins are abnormally deposited in organs and/or tissues. A protein is described as being amyloid if, due to an alteration in its secondary structure, it takes on a particular aggregated insoluble form similar to the beta-pleated sheet.  Symptoms vary widely depending upon the site of amyloid deposition. Amyloidosis may be inherited or acquired.

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The collection of these abnormal proteins interferes with the normal functioning of the organ affected.

Since there are more than 20 different proteins that may form amyloid, there are also many different types of amyloidosis.

Classification of amyloid:
The modern classification of amyloid disease tends to use an abbreviation of the protein that makes the majority of deposits, prefixed with the letter A. For example amyloidosis caused by transthyretin is termed “ATTR.” Deposition patterns vary between patients but are almost always composed of just one amyloidogenic protein. Deposition can be systemic (affecting many different organ systems) or organ-specific. Many amyloidoses are inherited, due to mutations in the precursor protein. Other forms are due to different diseases causing overabundant or abnormal protein production – such as with over production of immunoglobulin light chains in multiple myeloma (termed AL amyloid), or with continuous overproduction of acute phase proteins in chronic inflammation (which can lead to AA amyloid).

Out of the approximately 60 amyloid proteins that have been identified so far,  at least 36 have been associated in some way with a human disease.

Amyloidosis is rare, being diagnosed in between one and five in every 100,000 people every year. It’s more common in older people and is also slightly more common in men than in women.

Causes:
The cause of primary amyloidosis is unknown, but the condition is related to abnormal production of antibodies by a type of immune cell called plasma cells.

The symptoms depend on the organs affected by the deposits. These organs can include the tongue, intestines, skeletal and smooth muscles, nerves, skin, ligaments, heart, liver, spleen, and kidneys.

Primary amyloidosis can result in conditions that include:

•Carpal tunnel syndrome
•Gastrointestinal reflux (GERD)
•Heart muscle damage (cardiomyopathy)
•Kidney failure
•Malabsorption
The deposits build up in the affected organs, causing them to become stiff, which decreases their ability to function.

Risk factors have not been identified. Primary amyloidosis is rare. It is similar to multiple myeloma, and is treated the same way.

Symptoms:

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•Enlarged tongue
•Fatigue
•Irregular heart rhythm
•Numbness of hands and feet
•Shortness of breath
•Skin changes
•Swallowing difficulties
•Swelling in the arms and legs
•Weak hand grip
•Weight loss

Additional symptoms that may be associated with this disease:
•Clay-colored stools
•Decreased urine output
•Diarrhea
•Hoarseness or changing voice
•Joint pain
•Other tongue problems
•Weakness

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Diagnosis:
Exams and Tests
Your doctor may discover that you have an enlarged liver or spleen.

If specific organ damage is suspected, your doctor may order tests to confirm amyloidosis of that organ. For example:

•Abdominal ultrasound may reveal a swollen liver or spleen.
•An abdominal fat pad biopsy, rectal mucosa biopsy, or a bone marrow biopsy can help confirm the diagnosis.
•A heart evaluation, including an ECG,may reveal arrhythmias, abnormal heart sounds, or signs of congestive heart failure. An echocardiogram shows poor motion of the heart wall, due to a stiff heart muscle.
•A carpal tunnel syndrome evaluation may show that hand grips are weak.Nerve conduction velocity shows abnormalities.
•Kidney function tests may show signs of kidney failure or too much protein in the urine ( nephrotic syndrome).
?BUN level is increased.
?Serum creatinine is increased.
?Urinalysis shows protein, casts, or fat bodies.

This disease may also alter the results of the following tests:
•Bence-Jones protein (quantitative)
•Carpal tunnel biopsy
•Gum biopsy
•Immunoelectrophoresis – serum
•Myocardial biopsy
•Nerve biopsy
•Quantitative immunoglobulins
•Tongue biopsy
•Urine protein

Treatment:
It isn’t always easy to treat amyloidosis, and there is no treatment yet that specifically targets the amyloid depositing in the tissues. In cases where it’s secondary to another problem (AA amyloidosis), such as rheumatoid arthritis, treating that original problem may stop the progress of amyloidosis or may even reverse it.

In cases of primary amyloidosis (AL amyloidosis), chemotherapy drugs may be given to suppress production of new amyloid and cause regression of existing amyloid deposits.

In secondary amyloidosis, aggressive treatment of the underlying disease can improve symptoms and/or slow progression of disease. Complications such as heart failure, kidney failure, and other problems can sometimes be treated as necessary.

Occasionally, transplantation of a damaged organ is necessary. However, even after this has been carried out the new organ may become affected by amyloidosis.

Treatment may also be aimed at supporting the function of damaged tissues and treating complications such as heart or kidney failure.

Overall, many types of amyloidosis follow a steadily progressive course and may prove fatal within a year or two.

Prognosis :
The severity of the disease depends upon the organs affected. Heart and kidney involvement may lead to organ failure and death. Systemic involvement is associated with death within 1 to 3 years.

Possible Complications:
•Congestive heart failure
•Death
•Endocrine failure (hormonal disorder)
•Kidney failure
•Respiratory failure

Prevention : There is no known prevention.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.bbc.co.uk/health/physical_health/conditions/amyloidosis1.shtml
http://www.nlm.nih.gov/medlineplus/ency/article/000533.htm
http://en.wikipedia.org/wiki/Amyloidosis

http://health.allrefer.com/pictures-images/amyloidosis-on-the-face.html

http://health.allrefer.com/health/cardiac-amyloidosis-dilated-cardiomyopathy.html

http://morningreporttgh.blogspot.com/2010/04/amyloidosis.html

http://gsm.utmck.edu/research/HICP/overview.cfm

http://www.pathologyatlas.ro/amyloidosis-kidney-pathology.php

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Dengue Virus Growth Protein Identified

A TEM micrograph showing Dengue virus virions ...
Image via Wikipedia

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By silencing genes one by one, scientists have identified dozens of proteins that help the dengue fever virus to grow and spread among  mosquitoes and humans. The research paves the way to potentially prevent or treat the disease, which infects millions worldwide every year.

Dengue is a mosquito-borne illness that can cause debilitating sickness and death. “Dengue is a nasty disease, and right now, there is no treatment for it and no way to prevent it,” said Mariano Garcia-Blanco, professor of molecular genetics and microbiology at Duke University Medical Centre (DUMC) and study co-author.

“But if we can find a weakness in the virus, we can design a strategy to fight it. This study has helped us identify some gaps in dengue’s armour,” he said.

Almost half the people in the world are vulnerable to the dengue virus, says the World Health Organisation. Public health officials are worried because dengue appears to be popping up in places where it has rarely appeared before. It may be fuelled by global warming.

Garcia-Blanco, used RNA interference (RNAi) to unlock dengue’s secrets. RNA interference is a normal biological process cells use to turn gene expression on or off depending upon which gene products, or proteins, are needed at any given moment.

“That very same system proved to be the perfect investigative tool for our study,” said Garcia-Blanco.

Garcia-Blanco and colleagues in Duke’s RNAi facility were able to knock down gene function in fruit fly cells infected with a strain of the dengue virus known as DENV-2.

Silencing one gene at a time allowed researchers to pinpoint which genes, or host factors, were essential to viral growth and which ones were not.

They used fruit flies as a model because the genetic tools needed for the same work in mosquitoes have not been developed as yet. The process yielded 116 host factors that appeared to be important for successful dengue infection in fruit flies.

In testing several of these host factors in mosquitoes at Johns Hopkins University, researchers subsequently discovered that at least one – and possibly a second – was necessary for dengue infection to occur in the insects, said a DUMC release.

Sources: The Times Of India

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The Promise and Power of RNA

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People whose bodies make an unusually active form of a certain protein tend to have dangerously high levels of cholesterol. Those with an inactive form of the protein have low cholesterol and a low risk of heart attacks.

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Needless to say, pharmaceutical companies would love to find a drug that can attach itself to the protein and block its activity. That might be difficult for this protein, which is called PCSK9. But a powerful new approach, called RNA interference, may surmount that obstacle. Instead of mopping up a protein after it has been produced, as a conventional drug would do, RNA interference turns off the faucet, halting production of a protein by silencing the gene that contains its recipe.

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In monkeys, a single injection of a drug to induce RNA interference against PCSK9 lowered levels of bad cholesterol by about 60%, an effect that lasted up to three weeks. Alnylam Pharmaceuticals, the biotechnology company that developed the drug, hopes to begin testing it in people next year.

The drug is a practical application of scientific discoveries that are showing that RNA, once considered a mere messenger boy for DNA, actually helps to run the show. The classic, protein-making genes are still there on the double helix, but RNA seems to play a powerful role in how genes function.

“This is potentially the biggest change in our understanding of biology since the discovery of the double helix,” said John Mattick, a professor of molecular biology at the University of Queensland in Australia. And the practical impact may be enormous.

RNA interference, or RNAi, discovered only about 10 years ago, is attracting huge interest for its seeming ability to knock out disease-causing genes. There are already at least six RNAi drugs being tested in people, for illnesses including cancer and an eye disease. And while there are still huge challenges to surmount, that number could easily double in the coming year.

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Sources: The Times Of India

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