There are plenty of great scientific research stories out this week. Here’s a look at just a few of them.
Pregnancy and Reproductive History May Influence Dementia Risk
Research presented at the Alzheimer’s Association International Conference (AAIC) 2018 in Chicago by researchers from Kaiser Permanente and UC Davis looked at the relationships between dementia and number of children, number of miscarriages, age at first menstrual period, menopause, and months of pregnancy and hormone therapy. Part of the reason for the study, which was the first-ever large-scale epidemiological study in the U.S., was to investigate why more women than men have Alzheimer’s and other dementias. The study looked at self-reported data from 14,595 women between the ages of 40 and 55 in 1964 through 1973.
For example, the researchers found that women with three or more children had a 12 percent lower risk of dementia compared to women with only one child. They were also determined to be at lower risk after adjusting for other mid- and late-life risk factors, like body mass index and history of stroke. Each extra report of a miscarriage was linked to a nine percent increased risk of dementia compared to women who did not report miscarriages. Women who indicated their first menstrual period at age 16 or older had a 31 percent greater risk of dementia than women who reported having their first period at 13. Women who had natural menopause after age 45 were at 28 percent greater dementia risk than women who experienced natural menopause at 45 or younger.
A second study conducted of 133 elderly women in Britain by Molly Fox, assistant professor, Departments of Anthropology and Psychiatry & Biobehavioral Sciences at the University of California, Los Angeles, linked the number of months of pregnancy, especially first-trimester months, is a significant predictor of Alzheimer’s risk. Women who spent 12.5 percent more months pregnant than otherwise identical women had about a 20 percent lower risk of Alzheimer’s disease. “We are intrigued by the possibility that pregnancy may reorganize the mother’s body in ways that could protect her against developing Alzheimer’s later in life,” Fox said in a statement. “These results also suggest that the story might not be so simple as being all about estrogen exposure, as previous researchers have suggested.”
A New Way to Defend Against HIV?
Researchers at Texas Biomedical Research Institute published research in the journal AIDSshowing that an antibody called Immunoglobulin M (IgM) was able to prevent HIV-1 infection after exposure to mucosal AIDS virus. “IgM is sort of the forgotten antibody,” said Ruth Ruprecht, scientist and director of Texas Biomed’s AIDS Research Program, in a statement. “Most scientists believed its protective effect was too short-lived to be leveraged as any kind of protective shield against an invading pathogen like HIV-1.”
The work was conducted in rhesus monkeys, who were first treated with a human-made version if IgM. Thirty minutes later the same animals were exposed to simian-human immunodeficiency virus (SHIV). Four of the six monkeys were fully protected from the virus.
Identifying How Obesity Causes Disease
Although widely associated with disease, the actual mechanisms of how obesity causes disease haven’t been completely identified. Researchers from the University of Virginia School of Medicine published research in the Proceedings of the National Academy of Sciences describing some of the mechanisms. The key finding is that free radicals in the body react with lipids in fat tissue that causes inflammation. “All these diseases have a common denominator,” said researcher Vlad Serbulea, in the university’s Department of Pharmacology, in a statement. “It may well be that we’ve identified what starts off the whole cascade of inflammation and metabolic changes.”
Serbulea continued, “Free radicals are so reactive that they want to hitch onto something. Lipids happen to be a very good sink for these radicals to combine with.”
Which leads to what is called lipid oxidation. Some of the oxidized lipids caused inflammation, which caused immune cells to be hyperactive, but other oxidized lipids were observed in healthy tissue. What they found was that the protective lipids were truncated or shorter, while the inflammatory ones were full length.
Diet and Liver Linked to Increased Alzheimer’s Risk
A class of lipids made in the liver called plasmalogens are vital to cell membranes in the brain. And lower levels of these lipids are linked to an increased risk of Alzheimer’s disease. This research was presented this week at the Alzheimer’s Association International Conference (AAIC) 2018 by Mitchel Kling, an associate professor of Psychiatry in the Perelman School of Medicine at the University of Pennsylvania and the Veterans Affairs Medical Center.
Kling and a multi-institutional Alzheimer’s Disease Metabolomics Consortium led by Rima Kaddurah-Daouk at Duke University School of Medicine created three indices for measuring the amount of these lipids as they relate to cognition as a way to identify if reduced levels in the blood are linked to an increased risk of Alzheimer’s, mild cognitive impairment (MCI), overall cognition, and other biomarkers of neurodegeneration in Alzheimer’s. The measurements were the ratios of plasmalogens to each other, the ratio of plasmalogens to their more conventional lipid counterparts, and a combination of the two.
“This research shows that an age-related deficiency of plasmalogens could lead to an increased risk of Alzheimer’s disease, because the liver cannot make enough of them,” said Kling in a statement. “This research has a variety of interesting implications. For example, it highlights a potential relationship between conditions such as obesity and diabetes and Alzheimer’s—as the liver has to work harder to break down fatty acids over time. This could lead to the eventual destruction of the peroxisomes that create plasmalogens which thus, increases the risk of Alzheimer’s.”
Shift Work Can Cause Insulin Resistance
Researchers from Maastricht University in the Netherlands published research in the Proceedings of the National Academy of Sciences (PNAS) that linked changes in circadian rhythm caused by shift was led to an increased risk of metabolic diseases like type 2 diabetes. The researchers stimulated short-term night shift work, which resulted in significant decrease in muscle insulin sensitivity related to a cut in skeletal muscle nonoxidative glucose disposal. They noted that fasting glucose and free fatty acid levels, as well as sleeping metabolic rate, were higher during the circadian misalignment.
The researchers noted, “During simulated short-term night shift work insulin sensitivity at the level of skeletal muscle is decreased in male volunteers, which could contribute to the development of type 2 diabetes in the long term. We also find that the muscle molecular clock does not align rapidly to the new behavioral cycle. Importantly, on the left of the transcriptome, circadian misalignment induced upregulation of fatty acid metabolism pathways, potentially resulting in substrate competition on the cellular level.”
Because Everybody Loves Koalas
Researchers with the Australian Museum Research Institute, Australian Museum in Sydney, Australia, sequenced the koala genome, creating a complete and contiguous marsupial reference genome. One of the findings of the research was that the ability of the koala to detoxify eucalyptus leaves may be related to expansions within a cytochrome P450 gene family. They also found that the cuddly bears’ ability to smell, taste and moderate ingestion of plant secondary metabolites might be because of expansions in the vomeronasal and taste receptors.
The researchers note that, in addition to being the only extant species of the marsupial family Phascolarctidae, and are classified as “vulnerable” because of habitat loss and widespread disease, koalas eat almost exclusively Eucalyptus. Eucalytpus not only has low calorie content, but is toxic or fatal to most other mammals. To date, how they manage to digest it has been “elusive, as there are no koala research colonies and access to milk and tissue samples is opportunistic.”
Current estimates of Australian koalas range from 144,000 to 605,000, with continuing decline expected. In addition to problems with habitat and a very limited diet, they are victims of koala retrovirus (KoRV) and Chlamydia.
Koalas have 16 chromosomes (humans have 46). The researchers sequenced the complete genome.
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