Clinical Trials September-October 2006

Article Highlights:
by Quest Staff on September 1, 2006 - 3:11pm

QUEST Vol. 13, No. 5

Valproic acid improves strength in SMA study

The drug valproate (valproic acid), currently used for seizures, bipolar disorder and migraine headaches, increased ob-jective and subjective strength assessments in six adults with type 3 or 4 spinal muscular atrophy (SMA).

Laboratory experiments have suggested that valproate can increase the level of full-length SMN protein molecules, needed but deficient in SMA, in cells from people with the disease.

Conrad Weihl and colleagues, with MDA clinic director Alan Pestronk at Barnes-Jewish Hospital in St. Louis, gave valproate to seven people, ages 17 to 45, with SMA, for an average of eight months. One participant withdrew from the study after one month because of concerns about weight gain.

The average strength gain during the study was 48 percent.

One person, a wine maker, was able to return to picking grapes; and a high school student was able to return to marching in the band. Others noted improvements in their ability to rise from a chair, dress themselves or breathe deeply.

In another study, in the June issue of Annals of Neurology, researchers in Germany say they’ve found evidence that valproic acid can increase full-length SMN levels in SMA carriers and patients.

Lars Brichta at the University of Cologne, and colleagues, who studied 20 people with SMA and 10 SMA carriers taking valproic acid, caution that they measured blood cell SMN levels, which may not correlate with SMN levels in nerve cells or with muscle strength. However, they call the finding “a major step toward the development of a treatment for SMA.”


Aerobic exercise beneficial in McArdle’s

Moderate exercise on a stationary bicycle markedly improved the exercise capacity of eight people with McArdle’s disease, researchers at the University of Texas Southwestern Medical Center in Dallas and the University of Copenhagen (Denmark) have found.

MDA grantee Ronald Haller, at UT Southwestern, and colleagues, reported in the June [2006] issue of Annals of Neurology that regular aerobic exercise is safe and beneficial in this condition.

Keith Stout exercising
When subjects with McArdle's disease exercised with a heart rate of 60 percent to 70 percent of maximum, they were able to perform for 30 to 40 minutes, four times a week.

Aerobic exercise relies on “oxidative” energy production, which takes place inside the muscle cells’ mitochondria (metabolic centers). People with McArdle’s disease, also known as muscle phosphorylase deficiency, can’t use glycogen, the stored form of sugar, for energy, so they have to rely on alternative fuels from the bloodstream, such as the sugar glucose.

Dietary interventions to improve exercise capacity in McArdle’s, except for a high-sugar meal 40 minutes before exercise, have been ineffective, the investigators say. (A high-sugar meal increases blood glucose levels, but the effect is relatively short-lived and may cause unwanted weight gain.)

A concern about exercise in McArdle’s disease is that pushing exercise beyond one’s fuel supply limits can cause potentially severe muscle damage and even kidney damage from a protein (myoglobin) that leaks out of disintegrating muscle cells.

Keith Stout exercising

The Texas and Copenhagen investigators found, however, that when their subjects exercised with a heart rate of 60 percent to 70 percent of maximum for their ages, they were able to perform 30 to 40 minutes of exercise, four times a week, without evidence of muscle damage.

Study participants were monitored for 14 weeks, during which they were asked to pedal a stationary bicycle at an intensity that brought their heart rate to between 95 and 130 beats per minute, depending on age.

“Since maximal heart rate declines with age and can be estimated as 220 beats per minute minus age in years, we recommend a target heart rate range of 120 to 140 for patients 20 years old, 110 to 130 for those 40 years old, and so on,” Haller said. “Ideally, training should be discussed with and monitored by a physician familiar with McArdle’s disease.”


Life satisfaction study yields some surprises

A recently completed questionnaire that reached 228 adults with neuromuscular or neurological disorders produced some results consistent with previous research and commonly held beliefs, and some surprising answers.

The study, conducted by Roy Chen, a graduate student in the rehabilitation counseling program at Michigan State University in East Lansing, found that participants with relatively high levels of physical functioning reported more satisfaction with their lives than did other participants. It also found that having hope for amelioration of the disability correlated with a high acceptance of the disability; and that married people reported a higher level of life satisfaction than did never married or divorced subjects.

More surprisingly, results didn’t show employment status as a significant contributor to life satisfaction. And the study found that people with strong religious convictions were less accepting of their own disabilities than those without strong beliefs.

People with long-standing disabilities reported being more satisfied than people with disabilities of more recent onset. And the women in the study were in general more satisfied with their lives than the men.

Chen notes that the study involved a relatively small number of participants, and didn’t try to determine personality or attitudinal differences between those who responded to the survey completely, partially or not at all.


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