News from the latest research

LINK BETWEEN OSA AND OSTEOPOROSIS

Older individuals and women diagnosed with obstructive sleep apnea (OSA) may be at a higher risk for osteoporosis, according to a study recently published in the Journal of Clinical Endocrinology & Metabolism.

OSA is associated with metabolic, endocrine, and cardiovascular diseases because it causes ongoing sleep disruptions and periodically deprives the body of oxygen. fle researchers, led by Kai-Jen Tien, MD, of Chi Mei Medical Center in Tainan, Taiwan, noted that population-based studies show that 4% of men and 2% of women over 50 sufier from OSA.

Tien and team studied a retrospective cohort of 1,377 people who had been diagnosed with OSA from 2000 to 2008, using records from Taiwan’s single-payer National Health Insurance program. fley then compared the rate of osteoporosis diagnosis in this group to a matched cohort of 20,655 without OSA. “All patients were tracked until an osteoporosis diagnosis, death, or the end of 2011,” the authors wrote.

The scientists wrote that they wanted to investigate the “possible association between OSA and osteoporosis.” What they found was a clear link. During the six-year follow-up period, “the incidence rates of osteoporosis in the OSA cohort and comparison group were 2.52 and 1.00 per 1,000 person-years, respectively. Patients with OSA were found to be at 2.74 times the risk of osteoporosis than patients without OSA (95% CI = 1.69 – 4.44, p < 0.05) after adjustment for age, gender, diabetes, hypertension, coronary artery disease, obesity, stroke, hyperlipidemia, chronic kidney disease, gout, monthly income, and geographical location.” “As more and more people are diagnosed with obstructive sleep apnea worldwide, both patients and healthcare providers need to be aware of the heightened risk of developing other conditions,” Tien said. “We need to pay more attention to the relationship between sleep apnea and bone health, so we can identify strategies to prevent osteoporosis.”

VITAMIN D
MAY RAISE CANCER
SURVIVAL RATES

Cancer patients with higher circulating 25(OH)D (vitamin D) levels at or near the time of their diagnosis have been shown to have better survival rates and remain in remission longer than their vitamin D-deficient counterparts, a study recently published in the Journal of Clinical Endocrinology & Metabolism showed.

According to the researchers, led by Hui Wang, MD, PhD, of the Institute for Nutritional Sciences at the Shanghai Institutes for Biological Sciences of the Chinese Academy of Sciences, vitamin D insufficiency is “prevalent all over the world,” and epidemiologic studies “suggest that vitamin D deficiency leads to an increased risk of colorectal, breast, lung, pancreatic, bladder, kidney, ovarian, and thyroid cancers.”

The scientists performed a metaanalysis of 25 studies comprising 17,332 cases, measuring vitamin D levels in cancer patients at the time of diagnosis and tracking survival rates. fley found that “a 10 nmol/L increment in circulating 25(OH)D levels conferred an HR of 0.96 (95% CI = 0.95 – 0.97) for overall survival of the cancer patients,” with the strongest link between vitamin D levels and survival in breast cancer, lymphoma, and colorectal cancer.

“Our analysis demonstrated that vitamin D levels are linked to better outcomes in several types of cancer,” Wang said. “The results suggest vitamin D may influence the prognosis for people with breast cancer, colorectal cancer, and lymphoma, in particular. Considering that vitamin D deficiency is a widespread issue all over the world, it is important to ensure that everyone has sufficient levels of this important nutrient. Physicians need to pay close attention to vitamin D levels in people who have been diagnosed with cancer.”

MHO INDIVIDUALS AT HIGHER RISK OF HEART DISEASE

A lot has been made recently of the phenomenon of metabolically healthy obese (MHO) people, but according to research recently published in the Journal of the American College of Cardiology, MHO individuals have a higher prevalence of early plaque buildup in their arteries than their normal-weight counterparts.

Yoosoo Chang, MD, of Kangbuk Samsung Hospital Total Healthcare Center, Center for Cohort Studies in Seoul, Korea, and colleagues set out to compare coronary artery calcium (CAC) scores of MHO and metabolically healthy normal-weight participants. They used a cross-sectional study to look at 14,828 metabolically healthy Korean adults ages 23 to 77 with no known cardiovascular disease and who underwent a checkup exam that included an estimation of CAC scores. The authors wrote, “Being metabolic healthy was defined as not having any metabolic syndrome component and having a homeostasis model assessment of insulin resistance (HOMA-IR) <2.5.” The researchers also determined obesity or normal weight using a “standard Asian BMI index scale,” meaning obesity was defined as a BMI of 25. The CAC scores showed that MHO individuals had a higher prevalence of coronary calcification than those with normal weight. “In multivariable adjusted models,” the authors wrote, “the CAC score ratio comparing MHO to normal weight participants was 2.26 (95% CI = 1.48 – 3.43). In mediation analyses, further adjustment for metabolic risk factors markedly attenuated this association, which was no longer statistically significant (CAC score ratio 1.24, 95% CI = 0.79 – 1.96). These associations did not differ by clinically relevant subgroups.” The scientists went on to conclude that MHO “is not a harmless condition,” as the study showed that MHO participants had a higher prevalence of subclinical coronary atherosclerosis compared to normalweight participants. “Obese individuals who are considered ‘healthy’ because they don’t currently have heart disease risk factors, should not be assumed healthy by their doctors,” Chang said in a statement. “Our research shows that the presence of obesity is enough to increase a person’s risk of future heart disease and that the disease may already be starting to form in their body. It’s important that these people learn this while they still have time to change their diet and exercise habits to prevent a future cardiovascular event.”

HYPOTHALAMIC miRNAs AND METABOLIC DISTRESS

Researchers in Spain have identified several sets ofmicroRNAs (miRNAs) whose expressions are thought to have a direct impact on metabolic conditions, according to research recently published in Endocrinology.

Susana Sangiao-Alvarellos, PhD, of the University of A Coruna, and her team wrote that it is now clear that obesity is a “multifaceted condition in which genetic load, developmental programming, and environmental factors are major contributing factors,” rather than the old idea that obesity was triggered by “isolated metabolic insults” or simply eating too much.

The scientists went on to point out that miRNAs “have been recognized as key regulators in different biological processes, including insulin sensitivity and glucose metabolism.” However, the roles of miRNA pathways have been mostly relegated to “peripheral tissues” and “deregulation of miRNA expression in the hypothalamus in conditions of metabolic distress remains so far unexplored.”

The researchers set out to explore just that, using high-throughput screening to define to what extent the hypothalamic profiles ofmiRNA expression are perturbed in two extreme conditions of nutritional stress in male rats, namely chronic caloric restriction (CR) and HFD-induced obesity. The team found that their analyses “allowed the identification of sets ofmiRNAs, including let-7a, mir-9, mir-30e, mir-132, mir-145, mir-200a, and mir-218, whose expression patterns in the hypothalamus were jointly altered by CR and/or HFD.”

The authors concluded, “The predicted targets of these miRNAs include several elements of key infiammatory and metabolic pathways, including insulin and leptin.” They also determined that their study is the Thrst to disclose the impact of nutritional challenges on the hypothalamic miRNA expression proThles. “These data will help to characterize the molecular miRNA signature of the hypothalamus in extreme metabolic conditions,” they wrote, “and pave the way for targeted mechanistic analyses on the involvement of deregulated central miRNAs pathways in the pathogenesis of obesity and related disorders.”

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