Tag: Ageing

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Ant-y-insulin

Long live queens! But why?
Ovaries might change growth cues
to extend lifespan!

By Dr Nathan Woodling

A queen takes the throne.
Insulin surges, eggs grow.
A switch extends life.

By Dr Andrew Holmes

Reproduction is linked to reduced lifespan in many animals, yet ant queens have a far greater longevity compared to workers in their colony – black garden ant queens can live up to 30 times longer than the 1-year lifespan of their workers. Ant queens have the same genome as their workers, and in some species of ant they aren’t reared differently but switch caste following the death of the current queen.

The Indian jumping ant (Harpegnathos saltator) exhibits this switching behaviour. When a queen dies, workers duel each other, with the winners transitioning into pseudo-queens known as gamergates. These gamergates begin laying fertile eggs and their lifespan is substantially increased – from 7 months to 4 years. Gamergates can even transition back into the worker caste if replaced by another queen, their lifespan reverting back to 7 months.

How is ant lifespan so mutable?

New research by Yan et al. (2022) points to an insulin-suppressing protein as a possible answer.

The researchers compared gene expression during caste switching and found that ants that switch from worker to gamergate produce more insulin. The increased insulin results in a change in the balance of activity between the two main insulin signalling pathways, MAPK (which controls metabolism and egg formation) and AKT (which controls ageing).

On transitioning to a gamergate, the MAPK insulin signalling pathway’s activity increases, inducing ovary development and the production of eggs. But this also results in the production of an insulin-suppressing protein (Imp-L2) which blocks the AKT insulin signalling pathway, increasing longevity.

IMP-L2 essentially acts as a switch between a worker being short-lived and sterile compared to a queen being long-lived and fertile.

Original research:

http://dx.doi.org/10.1126/science.abm8767

A note about the sciku:

Nathan and Andrew independently wrote their sciku about this research and discovered the coincidence when Nathen posted his poem on Twitter. The two different approaches to writing about the same subject demonstrate why sciku are such a consistently interesting medium for exploring and sharing research.

Author bios:

Dr Nathan Woodling is a lecturer in molecular biosciences at the University of Glasgow. You can follow him on Twitter here: @NathanWoodling.

Dr Andrew Holmes is a former researcher in animal welfare and the founder and editor of The Sciku Project. You can follow him on Twitter here: @AndrewMHolmes.

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Optimism

Elixir of life
lies within our own outlook.
Old age will be great!

Meher Baba was on to something with when he came up with his adage “Don’t Worry, Be Happy”. The Indian spiritual master’s famous saying received global recognition in Bobby McFerrin’s chart-topping a cappella hit in 1988 (and later at the turn of the century thanks to ‘Big Mouth Billy Bass’).

Yet new research suggests that Meher Baba was on to something when he coined is famous phrase. Koga et al. (2022) tracked the longevity of more than 150,000 women over the course of 26 years and examined factors influencing morbidity and mortality including ethnicity, lifestyle and psychological outlook.

The researchers found that higher optimism was associated with longer lifespans, overall and across racial and ethnic groups. Whilst optimism is partly heritable, research shows that “optimism is modifiable with accessible methods that target optimism such as writing exercises and cognitive-behavioural strategies”.

All too often we focus on factors that negatively impact longevity. We should take a leaf out of Meher Baba’s book, be happy and remember the importance of thinking that the glass is half-full.

Intriguingly, whilst this research in the USA suggests the link between optimism and longevity, a study released earlier in 2022 by Okuzono et al. suggests that contrary to the latest research from Western populations, optimism is unrelated to longevity among Japanese older adults.

Original research:

Koga et al. (2022) https://doi.org/10.1111/jgs.17897

Okuzono et al. (2022) https://doi.org/10.1007/s10902-022-00511-8

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Yearning by Dr Kate Baker

In mid-2021 The Sciku Project teamed up with the Literature and Science Hub at the University of Liverpool to run the ‘Research in Verse Poetry Competition’, open to staff and postgraduate research students across the university to submit poems about their research subject. The competition saw poems addressing all sorts of topics, ranging from gravity to slavery to life in the lab.

Dr Kate Baker’s nostalgic haiku on the perils of academic career progression was a notable entry:

Yearning

Test tubes and pipettes?
A life spent on email
yearning for the bench

Background

It’s not so much my research as the transition from postdoc to principal investigator that inspired my poem.

Dr Kate Baker is a Senior Lecturer and leader of The Bakery – an applied microbial genomics laboratory at the University of Liverpool. You can connect with her on Twitter here: @ksbakes.

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Whale shark

Sir Fish of the Stars.
Legacy of violence
reveals your true age.

The whale shark is the largest known fish species on the planet, with the longest specimen recorded at 18.8 meters. These gentle giants swim slowly through tropical waters, filter feeding on plankton and small fishes. No one is clear on how long-lived they are – like all sharks they lack the bony structures (otoliths) that are normally used to assess age in other fish species. Yet researchers now think they have the answer, and it lies in the legacy of the cold war.

Whale shark vertebrate have growth bands that increase as they age, rather like tree rings. The trouble is that without knowing how rapidly these bands form it is hard to use them to work out the age of a whale shark. Yet researchers have worked out a useful method of providing a scale for the growth bands by using the effects of nuclear weapons testing.

In the 1950s and 1960s nuclear bomb tests were carried out by countries on both sides of the Cold War, including in the atmosphere. The result of these tests is that the levels of the naturally occurring radioactive element carbon-14 temporarily increased, entering the food web – including whale shark vertebrate.

Ong et al. (2020) used radiocarbon assays of the growth bands of vertebrate from 20 whale sharks caught by the Taiwanese fishery before it was closed in 2007. They found the sampled whale sharks ranged in age from 15 to 50, and that growth bands appear to form annually. The importance of this is key to conservation efforts as understanding population structure is fundamental to understanding threats to the populations.

A note about ‘Whale shark’: Their size and nature mean that whale sharks are widely respected around the world, even featuring on the 100-peso note in the Philippines. Whale sharks are called ‘marokintana’ in Madagascar, meaning ‘many stars’ in reference to the white markings on their dark backs, whilst in Vietnam they are known as ‘ca ong’ – literally translated as ‘sir fish’.

Original research: http://dx.doi.org/10.3389/fmars.2020.00188

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Aid pride

Got hearing aid shame?
No sense in letting age-pride
steal away your brain.

For many people the idea of needing a hearing aid is embarrassing, a sign of ageing that they don’t want to be reminded of or seen to need. Yet this shame may actually be harmful – a new study by Sarant et al. (2020) suggests that the use of a hearing aid may stave off cognitive decline.

The researchers assessed 99 adults aged between 60 and 84 before and after hearing aid use. After 18 months they found cognitive executive function (the higher level mental abilities used organise information, plan, and initiate and complete tasks) improved across the whole sample, especially in women.

Whilst sample sizes were small, the researchers also found that speech perception in quiet environments improved, as did participants’ self-reported quality of life and listening disability. This is an exciting development and, whilst further and larger studies are needed, it suggests that hearing aids may help to delay cognitive decline.

Further reading: http://dx.doi.org/10.3390/jcm9010254

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Drug-Induced Hip Fractures

psychoactive drugs
flood and fog brains soon before
falls and hip fractures

by Dr Michael J. Leach

There is an inherent poetry to pharmacy whereby medicines can help people through intended beneficial effects and harm people through unintended adverse events, including side effects and drug-drug interactions. It is crucial for prescribers to carefully weigh up the risks and benefits of treatment whenever a new medicine is considered for any given patient. As the modern world has an aging population, there have been rises in frailty, multiple morbidities (i.e. multimorbidity), and multiple medicine use. Multiple medicine use can be defined in terms of polypharmacy, which denotes the concurrent use of five or more drugs, and hyper-polypharmacy, which denotes the concurrent use of ten or more drugs. The increasing prevalence of polypharmacy and hyper-polypharmacy means that, in modern society, there is high potential for harmful side effects and drug-drug interactions.

Psychoactive medicines are examples of drugs that have unfavourable side effects and that can interact with one another to cause harm. Psychoactive medicines act on the central nervous system in different ways to elicit therapeutic and adverse effects. The main types of psychoactive medicines are antidepressants, antipsychotics, benzodiazepines, benzodiazepine-related drugs, opioid analgesics, anticholinesterases, antiepileptics, and anti-Parkinson medicines. A common side effect across all these psychoactive medicines is sedation. While treatment with benzodiazepines, benzodiazepine-related drugs, and antipsychotics may be aimed at helping people to relax or sleep at night, the sedative effect can still be harmful when there is unwanted daytime sedation or oversedation. The sedative effects of psychoactive medicines likely explain why these drugs increase the risk of falls and fractures, especially in older, frailer individuals. Furthermore, when any one psychoactive medicine is taken with another psychoactive medicine, there is an increased sedative burden on the patient. This increased sedative burden can place people at an even greater risk of falls and fractures.

Pharmacoepidemiology is the population-level study of medicine use. In original research conducted as part of my PhD in Pharmacoepidemiology, I used a number of study designs and statistical methods to quantify the risk of hip fracture following psychoactive medicine use in older people. I focused on particular types of psychoactive medicines (e.g. antipsychotic drugs and selective serotonin reuptake inhibitor [SSRI] antidepressants) used individually and in combination with one another. The risk of hip fracture was increased for a range of psychoactive medicines, most notably when they were used concurrently. This research is relevant to real world medical practice because the risk factors identified are potentially modifiable. If prescribers better understand the risks associated with psychoactive medicine use, then they can make more informed prescribing decisions and de-prescribe psychoactive medicines where appropriate. Older patients, their carers, and their family members, as well as nursing home staff, would also benefit from better understanding the significant risk posed by the use of psychoactive medicines.

The pharmacoepidemiological studies that make up my PhD thesis have been published in peer-reviewed journals and are available online:

Leach MJ, Pratt NL, Roughead EE. The risk of hip fracture due to mirtazapine exposure when switching antidepressants or using other antidepressants as add-on therapy. Drugs – Real World Outcomes. 2017; 4(4): 247-255. http://dx.doi.org/10.1007/s40801-017-0120-y

Leach MJ, Pratt NL, Roughead EE. The risk of hip fracture in older people using selective serotonin reuptake inhibitors and other psychoactive medicines concurrently: a matched case-control study in Australia. Drugs – Real World Outcomes. 2017; 4(2): 87-96. http://dx.doi.org/10.1007/s40801-017-0107-8

Leach MJ, Pratt NL, Roughead EE. Psychoactive medicine use and the risk of hip fracture in older people: a case-crossover study. Pharmacoepidemiology and Drug Safety. 2015; 24(6): 576-582. https://doi.org/10.1002/pds.3785

Leach MJ, Pratt NL, Roughead EE, Hayward K, Jenkins N. Medicine use among the elderly before and after hip fracture. Australian Journal of Pharmacy. 2014; 95(1125): 72-74. [A secondary publication arranged by the original publisher]. Available here.

Leach MJ, Pratt NL, Roughead EE. Medicine use among older Australians before and after hip fracture. Journal of Pharmacy Practice and Research. 2013; 43(4):265-268. https://doi.org/10.1002/j.2055-2335.2013.tb00271.x

Michael Leach (@m_jleach) is an Australian health researcher, biostatistician, and poet with a PhD in Pharmacoepidemiology and a passion for health humanities. Examples of his science poems are online here: https://imagesofhealth.wordpress.com/.

If you enjoyed this sciku, check out Michael’s other sciku ‘Quality of Life at Seven Years Post-Stroke‘ and ‘The Psychopharmacological Revolution‘, ‘The Core Correlate of Covid-19 Vaccine Acceptance’, ‘The Early Impacts of COVID-19 on Australian General Practice‘, ‘The Burden of Bushfire Smoke‘, and ‘Australian Science Poetry‘ with science communicator Rachel Rayner.

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Egg quality

Low egg quality –

the impact of age. Blocking

proteins slows decline.

 

As women age their reproductive ability decreases due to declining egg quality. However, research by Templeman et al (2018) suggests that blocking a particular group of proteins may help to slow this decline, potentially extending the reproductive period.

The proteins, known as cathepsin B proteases, are more common in age-degraded oocytes (unfertilised eggs) and appear to be part of the problem of decreasing quality. By blocking the proteins in C. elegans worms oocyte quality was maintained for much longer, regardless of whether the drug was administered at the beginning or part way through the worms’ reproductive period. Whilst it’s not ready for testing with humans, it points the way towards an interesting new approach.

Original research: http://dx.doi.org/10.1016/j.cub.2018.01.052

 

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Lurking inside intestines

The fountain of youth

lurking inside intestines:

Microbiota.

 

Gut microbes are important for digestion, nutrition and immunity, and gut microflora may impact on life expectancy. Young African turquoise killifish have diverse microbial communities but this diversity decreases over time. By feeding middle-aged killifish the microbes from younger fish, Smith et al (2017) found that the older fish lived longer and were more active in later life. Manipulating gut microbe composition may therefore be a way of delaying diseases related to ageing.