RESEARCH ETHICS By Kristie Sullivan, M.P.H., and Nancy Beck, Ph.D.
End of the Lethal Dose 50?
An international pharmaceutical organization has announced that its new standard will not require the Lethal Dose 50, or LD50, a crude test that measures the dose of a chemical that kills half the animals tested. The International Conference on Harmonization (ICH), the body charged with setting international pharmaceutical testing requirements, recommends that this information be obtained through other studies, which will save hundreds of animals a year from this painful test.
The landmark change is expected to go into effect in mid-2009. The ICH announcement comes after a consortium of pharmaceutical companies called for an end to the LD50 because its results were not used by regulatory authorities.
Researchers Use In Vitro Methods to Assess Nanomaterials
Nanotechnology—the branch of technology dealing with materials with very small dimensions—is creating more materials than can be assessed by commonly used animal toxicology tests, which are time-consuming and expensive. Meanwhile, new cell and tissue tests allow the assessment of hundreds or even thousands of chemicals in one day.
In the past year, two research teams have brought these two fields together by using batteries of in vitro tests to measure the potential toxicities of many different nanomaterials at one time. A Harvard University team used four tests with different cell types to assess 50 different nanomaterials, such as tiny particles of iron oxide, and used the results to categorize the nanomaterials by potential toxicity. This approach can also determine how different characteristics of new nanomaterials, such as coating material or surface area, might affect toxicity. Another team, based in the United Kingdom and China, used four different tests to predict the lung toxicity of 12 different nanomaterials.
Lu S, Duffin R, Poland C, et al. Efficacy of simple short-term in vitro assays for predicting the potential of metal oxide nanoparticles to cause pulmonary inflammation. Env Health Perspectives. 2009;117:241-247.
Shaw SY, Westly EC, Pittet MJ, et al. Perturbational profiling of nanomaterial biologic activity. PNAS. 2008;105:7387-7392.
Caption: Nanomaterials include the colloidal crystal solid above, which is used to create exceptionally durable and uniform ceramics. Nanoparticles are readily absorbed by the human body.
Draize Skin Test May Soon Be Outlawed in European Union
In February, the European Union accepted three nonanimal methods that may completely replace the Draize skin test, a test on rabbits used to measure skin irritation or corrosion by chemicals and other products. In cases where a nonanimal test is deemed at least equivalent to an animal test, EU law prohibits conducting the animal test.
The new methods use human skin cells—left over from cosmetic or other surgeries—reconstructed into three-dimensional tissues that look and act like human skin. They are available from MatTek Corporation in Ashland, Mass., or Skinethic in France.
This breakthrough is the result of collaborative research, funding, and advocacy efforts by animal protection groups, cosmetics and personal care companies, and independent laboratories.
Caption: Epiderm® from MatTek Corp.
NUTRITION By Susan Levin, M.S., R.D., and Kathryn Strong, M.S., R.D.
Diabetes Drugs Increase Women’s Fracture Risk
Avandia and Actos, two diabetes drugs, double the risk of bone fractures in women with type 2 diabetes, according to a new report by researchers at Wake Forest University and Britain’s University of East Anglia.
The researchers analyzed 10 studies of more than 14,000 diabetes patients and found that both drugs doubled women’s risk of bone fractures, but had no effect on men’s risk of bone fractures. The cause of the gender-specific effect on fractures was unclear, but researchers suggested the drugs may cause the problem by replacing bone marrow with fat cells.
The medications pose other concerns, particularly weight gain and increased risk of heart failure. Treatment costs around $110 per month. This new study highlights the need to promote lifestyle modifications in managing type 2 diabetes. PCRM’s recent study, published in the Journal of the American Dietetic Association, showed the benefits of a low-fat vegan diet for type 2 diabetes, without harmful side effects.
Singh S, Loke YK. The safety of rosiglitazone in the treatment of type 2 diabetes. Pharma Sci. 2008;7:579-585.
Turner-McGrievy GM, Barnard ND, Cohen J, Jenkins DJA, Gloede L, Green AA. Changes in nutrient intake and dietary quality among participants with type 2 diabetes following a low-fat vegan diet or a conventional diabetes diet for 22 weeks. J Am Diet Assoc. 2008;108:1636-1645.
Egg Consumption Raises Diabetes Risk
Daily consumption of eggs increases the likelihood of developing type 2 diabetes, according to a new study published in Diabetes Care. In this study of about 57,000 men and women from two large randomized trials, researchers found that daily egg intake was associated with a 77 percent and 58 percent increased risk for women and men, respectively.
Djoussé L, Gaziano JM, Buring JE, Lee I. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care. 2009;32:295-300.
High-Fat Diets Associated with Cardiovascular Disease
Another large study has found that people who consume the most fruits and vegetables have fewer heart attacks, while those who consume more meat, fried foods, and salty snacks have more heart attacks. This comparison of dietary patterns, published in Circulation, looked at heart attacks among more than 16,000 participants from 52 countries. Unhealthful diets accounted for about 30 percent of heart attacks worldwide.
Iqbal R, Anand S, Ounpuu S, et al. Dietary patterns and the risk of acute myocardial infarction in 52 countries: Results of the INTERHEART Study. Circulation. 2008;118:1929-1937.
Low-Carb Diet Impairs Memory
Dieters who eliminated carbohydrates scored lower on memory-based tests in a new study from Tufts University. Nineteen women consumed either a low-carbohydrate diet or a balanced, calorie-restricted diet and performed a series of cognitive tests. Over the three-week study, low-carbohydrate dieters showed a gradual decline in cognition, which returned to normal after carbohydrates were reintroduced.
D’Anci KE, Watts KL, Kanarek RB, Taylor HA. Low-carbohydrate weight loss diets. Effects on cognition and mood. Appetite. 2009;52:96-103.