Air pollution can worsen bone health

Some of the effects of air pollution on health are well documented – lung cancer, stroke, respiratory diseases – but for others there is less scientific evidence. Such is the case of bone health: there are only a few studies and results are inconclusive. Now, a study in India led by the Barcelona Institute for Global Health (ISGlobal), an institution supported by "la Caixa," has found an association between exposure to air pollution and poor bone health. The new study performed by the CHAI Project, led by ISGlobal and published in Jama Network Open, analyzed the association between air pollution and bone health in more than 3,700 people from 28 villages outside the city of Hyberabad, in southern India. The authors used a locally developed model to estimate outdoor exposure at residence to air pollution by fine particulate matter and black carbon. The participants also filled a questionnaire on the type of fuel used for cooking. The authors linked this information with bone health assessed using a special type of radiography that measures bone density, called dual-energy X-ray absorptiometry, and measured bone mass at the lumbar spine and the left hip. The results showed that exposure to ambient air pollution, particularly to fine particles, was associated with lower levels of bone mass. No correlation was found with use of biomass fuel for cooking. "This study contributes to the limited and inconclusive literature on air pollution and bone health," explained Otavio Ranzani, ISGlobal researcher and first author of the study. Regarding the possible mechanisms underlying this association, he says "inhalation of polluting particles could lead to bone mass loss through the oxidative stress and inflammation caused by air pollution." The article is titled “Association of Ambient and Household Air Pollution With Bone Mineral Content Among Adults in Peri-urban South India.”

Spine surgery is safe in patients of advanced age

Spine surgeons from seven institutions in Sapporo, Hokkaido, Japan, conducted a multicenter, prospective study of spine surgeries performed in patients 80 years of age and older. Although the overall perioperative complication rate was high – 20%, there were no major systemic complications and no deaths in the patients. The surgeons concluded that spine surgery is safe in this age group. Detailed findings of this study can be found in a new article, "Perioperative complications of spine surgery in patients 80 years of age or older: a multicenter prospective cohort study," by Takamasa Watanabe, and colleagues, published in the Journal of Neurosurgery: Spine. The authors of this study conducted a prospective multicenter study with two goals: 1) determine what perioperative complications of spine surgery are associated with patients in this advanced-age group and 2) investigate the risk factors for perioperative systemic complications. The patient group consisted of 270 patients, 80 years or older, who underwent elective spine surgery in 2017. The total perioperative complication rate in the study was 20% (67 complications in 54 patients). Complications at the surgical site occurred in 22 patients (8.1%), and minor systemic complications (anemia, delirium, or urinary tract infection) occurred in 40 patients (14.8%). No patient experienced a major systemic complication (one that could be potentially life-threatening or lead to prolonged hospitalization), and no patient died. The rate of repeated operations was 4.1%. Both the univariate and multivariate analyses identified spine surgery involving instrumentation (for example, inclusion of plates and screws), operations lasting more than 180 minutes, and the ECOG-PS (limited activities of daily living) as significant risk factors for minor systemic perioperative complications. The authors suggest that spine surgeons be aware of these risk factors when preparing for surgery in this advanced-age patient group. Older age itself, the presence of comorbidities, and being at nutritional risk were not found to be risk factors in this study.

Learning from the bears

Grizzly bears spend many months in hibernation, but their muscles do not suffer from the lack of movement. In the journal Scientific Reports, a team led by Michael Gotthardt reports on how they manage to do this. The grizzly bears' strategy could help prevent muscle atrophy in humans as well. The team investigated how the bear's muscles manage to survive hibernation virtually unharmed. The scientists from Berlin, Greifswald and the U.S. were particularly interested in the question of which genes in the bear's muscle cells are transcribed and converted into proteins, and what effect this has on the cells. To understand the bears' tricks, the team examined muscle samples from grizzly bears both during and between the times of hibernation, which they had received from Washington State University. They found proteins in their experiments that strongly influence a bear's amino acid metabolism during hibernation. As a result, its muscle cells contain higher amounts of certain non-essential amino acids (NEAAs). "In experiments with isolated muscle cells of humans and mice that exhibit muscle atrophy, cell growth could also be stimulated by NEAAs," said Gotthardt, adding that "it is known, however, from earlier clinical studies that the administration of amino acids in the form of pills or powders is not enough to prevent muscle atrophy in elderly or bedridden people." A therapeutic starting point, he says, could be the attempt to induce the human muscle to produce NEAAs itself by activating corresponding metabolic pathways with suitable agents during longer rest periods. In order to find out which signaling pathways need to be activated in the muscle, Gotthardt and his team compared the activity of genes in grizzly bears, humans and mice. With the help of these experiments, the team found a handful of genes whose influence they hope to further investigate in future experiments with mice. These include the genes Pdk4 and Serpinf1, which are involved in glucose and amino acid metabolism, and the gene Rora, which contributes to the development of circadian rhythms. "We will now examine the effects of deactivating these genes," said Gotthardt. "After all, they are only suitable as therapeutic targets if there are either limited side effects or none at all." The article is titled “Proteomic and Transcriptomic Changes in Hibernating Grizzly Bears Reveal Metabolic and Signaling Pathways that Protect against Muscle Atrophy.”

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