A study published in the journal Arthritis Research & Therapy reveals that there is a significant genetic component to the occurrence and severity of bone marrow lesions in the tibia and femur.
The study also shows that bone marrow lesions are more common in men and increase with age and weight.
Guangju Zhai, from St Thomas' Hospital, London, UK and colleagues from institutions in Australia studied 115 siblings from 48 families with a history of osteoarthritis. Zhai et al. used magnetic resonance imaging (MRI) to assess bone marrow lesions in the subjects. The authors then calculated the heritability estimates - or the extent to which they are hereditary - for bone marrow lesions in lateral and medial tibia and femur.
The results of Zhai et al.'s study show that the heritability estimate was 99% for the prevalence of bone marrow lesions in both lateral and medial compartments of the bones. The heritability estimates for the severity of bone marrow lesions are 53% for lateral bones and 65% for medial bones, after adjustment for age, sex, height, weight, muscle strength, knee pain and knee alignment.
The authors conclude that further studies to identify the gene(s) responsible for bone marrow lesions may help in the prevention and management of knee pain in osteoarthritis, the most common form of arthritis.
arthritis-research/
In a final study, CDC researchers passed a hybrid virus through a series of ferrets to see if the virus would accumulate genetic changes necessary to transmit more easily. The researchers found the process introduced only one genetic change in the virus but didn't enhance its transmissibility.
Although the findings apply only to the specific viruses used in the study, the research suggests that significant genetic changes in the H5N1 virus would likely be needed to create a strain that could cause a pandemic. Future CDC studies will examine whether combining genes from H3N2 strains with more recent H5N1 strains makes the new virus more easily transmissible.
"This study provides for the first time an assessment of the risk of an H5N1 pandemic strain emerging through reassortment with a human influenza virus. However, there is still much we do not know about the molecular changes the virus would need to cause a pandemic," said Dr. Jackie Katz, a branch chief in CDC's Influenza Division and one of the lead researchers on the paper. "Influenza viruses are constantly changing so we need to be vigilant and continue our work using this research method to better understand if there are other possible virus combinations or emerging changes in the H5N1 viruses that would increase the risk of a pandemic strain emerging."
Most influenza experts believe another pandemic will occur, but it is impossible to predict which strain will emerge as the next pandemic strain, when it will occur or how severe it will be. As of late July, H5N1 had caused more than 230 cases of disease in humans worldwide and is widespread in bird populations in Asia, Africa and Europe. However, the virus has only rarely passed between humans and does not currently transmit easily from human to human. H5N1 avian viruses have not been found in the United States in either birds or humans.
The research was done in collaboration with Centro Nacional de Biotecnologia, Madrid, Spain; National Institute of Hygiene and Epidemiology, Hanoi, Vietnam; and the Center for Biomedical and Pharmaceutical Research and Development, Ministry of Health, Jakarta, Indonesia, which provided reagents and viruses for the study. All laboratory work was conducted at CDC under stringent safety precautions.
cdc