Lack of Amino Acid Spurs Deadly Sickle Cell Complication
A deficiency of the amino acid arginine may contribute to the development of
pulmonary hypertension — a potentially deadly complication — in people with
sickle cell anemia, a new study suggests.
A process called hemolysis, in which red blood cells rupture, is what causes
the arginine deficiency, researchers said.
“Within the red blood cell, there is a high concentration of an
arginine-consuming enzyme called arginase,” said the study’s lead author, Dr.
Claudia Morris, the director of research for the pediatric emergency fellowship
at Children’s Hospital and Research Center in Oakland, Calif.
When arginase is released during hemolysis, explained Morris, that “triggers
a cascade of events that lead to pulmonary hypertension.”
The study findings appear in the July 6 issue of the Journal of the
American Medical Association.
Sickle cell anemia is a disease that causes red blood cells to become
sickle-shaped. This abnormal shape makes blood clots more likely, and when a
blood clot blocks a blood vessel it can cause extreme pain, according to the
National Institutes of Health (NIH). These damaged blood cells are also more
likely to break down prematurely in a process known as hemolysis. Sickle cell
disease strikes African-Americans more frequently than other racial groups.
An estimated one person of every three with sickle cell disease will
eventually develop pulmonary hypertension — high blood pressure in the arteries
of the lungs, Morris said. According to the NIH, pulmonary hypertension causes
the heart to work harder and become enlarged. Eventually, it can lead to heart
failure and death,
“It’s a life-threatening condition, and it’s what many adult sickle cell
patients die from,” she said.
For this study, Morris and her colleagues compared 228 people with sickle
cell anemia — ages 18 to 74 — to 36 healthy individuals.
The researchers measured blood amino acid levels and arginase activity. They
also tested all of the participants with sickle cell disease for pulmonary
hypertension using Doppler echocardiography — ultrasound of the lungs.
The researchers found that activity of the enzyme arginase was significantly
higher in people with sickle cell anemia than in the healthy individuals, and
those participants with pulmonary hypertension had the highest arginase
Arginase consumes an important amino acid, arginine, the researchers
explained. They found that study participants with the lowest amounts of
arginine were also 3.6 times more likely to die than those with the highest
levels of bioavailable arginine.
Arginine is normally sourced through foods such as nuts and meats. It’s also
available as a nutritional supplement, Morris said.
However, she doesn’t recommend that people with sickle cell disease start
supplementing their diet with arginine because researchers don’t know if that
will simply fuel heightened production of arginase. Instead, Morris believes
strategies that block the activity of arginase could prove more helpful.
“That would be an interesting hypothesis to test,” said Dr. Jay Brooks,
chairman of hematology and oncology at Ochsner Clinic Foundation Hospital in
Baton Rouge, La. “But, whether or not it will lead to a clinical intervention
remains to be seen.”
The findings from this study may also be useful in predicting who will
develop more severe sickle cell disease, and may eventually lead to earlier
treatments, Morris said.
“This study suggests that we may be able to identify patients who are at
greater risk of death,” she said. “This gives us a new way of thinking about
possible treatments, like nutritional supplements or inhibiting hemolysis
She added that more studies need to be done, so individuals affected by
sickle cell anemia with complications should ask their doctor about what
clinical trials might be available.
To learn more about sickle cell anemia, visit the National Library of
SOURCES: Claudia Morris, M.D., pediatric emergency physician, and
director of research for pediatric emergency medicine fellowship, Children’s
Hospital and Research Center, Oakland, Calif.; Jay Brooks, M.D., chairman,
hematology and oncology, Ochsner Clinic Foundation Hospital, Baton Rouge, La.;
July 6, 2005, Journal of the American Medical Association
Last Updated: July 5, 2005
Copyright © 2005 ScoutNews LLC. All
Overactive Bladder Disease: Why Diabetics Need To Be Screened Now
While some people with type 2 diabetes may not think that the number of times that they have to use the bathroom each day is related to their blood sugar condition, a recent study conducted by researchers indicated that many type 2 diabetes patients experience overactive bladder problems. The study found that among a group of nearly 1,400 men and women with type 2 diabetes, more than one-fifth had an overactive bladder.
What is overactive bladder?
Overactive bladder is a condition where the urinary bladder is unable to perform its usual function of storage of urine efficiently. Consequently, the patient suffers from symptoms like increased urgency to pass urine and at an increased frequency. The patient may have to get up frequently at night to void the bladder. He or she may also experience episodes of incontinence, which could interfere with his or her social life. Patients with urinary incontinence are said to be suffering from overactive bladder “wet” and patients without urinary incontinence are said to be suffering from overactive bladder “dry.”
Overactive bladder becomes more common with increasing age.
It often occurs due to increased muscle activity of the bladder, which could be a consequence of partial bladder obstruction, as in the case of prostate enlargement. The inner lining of the bladder could also play a role in bladder over-activity through the release of certain substances like prostaglandins, which stimulate the nerves and result in urgency.
People with diabetes are at a risk of developing overactive bladder.
Diabetes affects nerves; thus if nerves supplying to the bladder are affected, there could be an error in signals going to the bladder, resulting in urgency and voiding at the wrong time. This is one of the mechanisms suggested for the occurrence of overactive bladder in diabetes.
A study was carried out to study the prevalence of overactive bladder in patients with type 2 diabetes. The patients were administered a questionnaire to find out if they suffered from symptoms of overactive bladder.
Out of the total 1359 included in the study, 22.5% reported to be suffering from overactive bladder; 11.7% of these with overactive bladder dry and 10.8% with overactive bladder wet. Overactive bladder and overactive bladder wet were 2.4 and 4.2 times more common in patients with diabetes of more than 10 years duration, and of age more than 50 years. Men and older aged individuals were more likely to suffer from overactive bladder, whereas older individuals and people with a broader waist were more likely to suffer from incontinence due to the overactive bladder.
The above study reiterates that overactive bladder is common in people suffering from diabetes especially over a long duration; hence diabetics should be routinely screened for the presence of overactive bladder to ensure early treatment and prevent complications.