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Probiotics: Feeding mice harmless microbes prevents blood infection

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Feeding mice a probiotic of harmless bacteria helps prevent harmful microbes entering the blood where they could build up and potentially cause a condition called sepsis



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24 November 2021

Computer illustration of Bacillus subtilis bacteria

Science Photo Library / Alamy

Consuming a type of bacterium that is commonly found in soil helps mice avoid a blood infection that could potentially lead to sepsis, and the research might one day lead to treatments for people too.

Sepsis results from the activity of bacteria, including Enterococcus faecalis. These microbes can live in the human gut without causing disease, but in people who take antibiotics for prolonged periods, or treatments that weaken their immunity, E. faecalis can spread into the blood where it can cause body-wide infection. This is sepsis.

Now, for the first time, there is evidence from experiments in mice that consuming a probiotic can prevent blood infection. The probiotic was in the form of spores from another type of bacterium, Bacillus subtilis. These spores are dormant forms of the bacterium that don’t reproduce themselves and are highly resistant to environmental damage. On entering the gut, they activate and grow, influencing the growth of other bacteria in the intestine.

Michael Otto at the National Institute of Allergy and Infectious Diseases in Maryland and his colleagues first mimicked the treatment that people with blood cancer often receive, by giving mice the chemotherapeutic drug cyclophosphamide for a few days and then following this up with a cocktail of antibiotics.

The team then fed mice with two doses of either B. subtilis spores or a salt solution before a dose of E. faecalis the following day. The next day, the mice that had received the salt solution placebo treatment did have E. faecalis in their blood, where it could potentially cause sepsis, but those that had received the probiotic avoided blood infection.

Although neither group of mice had bacteria in the blood after three days, probably because the immune system cleared the microbes away, the team found E. faecalis in the liver and spleen of control mice at this stage, but not in the mice fed with the probiotic.

The team found that E. faecalis produces enzymes that made the gut leakier, helping them spread into the blood, and say the probiotic could be preventing this effect.

To test this idea, the group fed mice with a non-digestible fluorescent chemical, and then measured how much of this marker was present in the blood 4 hours later. The concentration of the marker was more than twice as high in mice that had received the placebo as it was in those that received probiotic. This suggests that the probiotic does counteract an increase in gut leakiness.

Consistent with this finding, the gut linings of mice treated with the placebo had hugely disorganised structures compared with mice treated with probiotic. The guts of placebo mice completely lacked villi, finger-like projections in the gut wall that absorb nutrients from food.

It is important to note that this work defines specific bacteria that can prevent sepsis caused by another particular species of bacterium, says Otto. This marks a distinction from the claims often made for other probiotics that suggest they have broad health benefits but without offering much detailed understanding of the process, says Otto.

“Addressing sepsis in a safe manner has large public health implications, particularly these days when microbial infections have never been so dramatically in the public eye,” says Glenn Gibson at the University of Reading, UK.

Journal reference: Science Translational Medicine, DOI: 10.1126/scitranslmed.abf4692

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Solar storms may cause up to 5500 heart-related deaths in a given year

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In an approximate 11-year cycle, the sun blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field, which may disrupt our body clock and ultimately affect our heart



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17 June 2022

A solar storm

Jurik Peter/Shutterstock

Solar storms that disrupt Earth’s magnetic field may cause up to 5500 heart-related deaths in the US in a given year.

The sun goes through cycles of high and low activity that repeat approximately every 11 years. During periods of high activity, it blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field.

These so-called solar storms can cause glitches in our power grids and bring down Earth-orbiting satellites. A handful of studies have also hinted that they increase the risk of …

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UK Covid infection rate rising, with more than a million cases in England | Coronavirus

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Coronavirus infections are rising in the UK, figures have revealed, with experts noting the increase is probably down to the more transmissible BA.4 and BA.5 Omicron variants.

The figures from the Office for National Statistics (ONS), based on swabs collected from randomly selected households, reveal that in the week ending 11 June an estimated one in 50 people in the community in England are thought to have had Covid – around 1.13 million people.

The figure is even higher, at one in 45, in both Wales and Northern Ireland, while it was highest in Scotland where, in the week ending 10 June, one in 30 people are thought to have been infected.

While the figures remain below the peak levels of infection seen earlier this year, when around one in 13 people in England had Covid, the findings are a rise on the previous week where one in 70 people in England were thought to be infected. Furthermore, the data reveals increases in all regions of England, except the north-east, and across all age groups.

Experts say that a key factor in the increase is probably the rise of the Covid variants of concern BA.4 and BA.5.

“Infections have increased across all four UK nations, driven by rising numbers of people infected with the BA.4 and BA.5 Omicron variants,” said Kara Steel, senior statistician for the Covid-19 Infection Survey.

While Steel said it remained too early to say if this was the start of another wave, others have warned it may already have begun, with increased mixing and travelling among other factors fuelling a rise in cases.

Among concerns scientists have raised are that BA.4, BA.5 and another variant on the rise, BA.2.12.1, replicate more efficiently in human lung cells than BA.2.

Prof Azra Ghani, an epidemiologist at Imperial College London, said the latest figures were not surprising, and might rise further.

“This increase in infection prevalence is likely due to the growth of the BA.4 and BA.5 Omicron subvariants, which as we have seen elsewhere in Europe, appear to be able to escape immunity generated from previous Omicron subvariants,” she said.

“It is therefore possible that we will continue to see some growth in infection prevalence in the coming weeks and consequently an increase in hospitalisations, although these subvariants do not currently appear to result in any significantly changed severity profile. This does however serve as a reminder that the Covid-19 pandemic is not over.”

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NHS to offer women in England drug that cuts recurrence of breast cancer | Breast cancer

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Thousands of women in England with breast cancer are to benefit from a new pill on the NHS which reduces the risk of the disease coming back.

The National Institute for Health and Care Excellence (Nice) has given the green light to abemaciclib, which cuts the chance of breast cancer returning after a patient has had surgery to remove a tumour.

Trials showed that patients who had the drug with hormone therapy had a more than 30% improved chance of their cancer not coming back after surgery, compared with hormone therapy alone.

“It’s fantastic thousands of women with this type of primary breast cancer will now have an additional treatment option available on the NHS to help further reduce the risk of the disease coming back,” said Delyth Morgan, the chief executive of charity Breast Cancer Now.

“The fear of breast cancer returning or spreading to other parts of their body and becoming incurable can cause considerable anxiety for so many women and their loved ones.

“New effective treatments such as abemaciclib, which can offer more women the chance to further reduce the risk of the disease recurring, are therefore extremely welcome and this is an important step change in the drug options available for this group of patients.”

The twice-a-day pill is suitable for women with hormone receptor-positive, HER2-negative, node-positive early breast cancer at high risk of recurrence who have had surgery. About 4,000 women will benefit initially, Nice said.

Helen Knight, the interim director of medicines evaluation at Nice, said the draft recommendation came less than a month after abemaciclib received its licence.

“The fact that we have been able to produce draft recommendations so quickly is testament to the success of our ambition to support patient access to clinically and cost effective treatments as early as possible,” said Knight. “Until now there have been no targeted treatments for people with this type of breast cancer.

“Abemaciclib with hormone therapy represents a significant improvement in how it is treated because being able to have a targeted treatment earlier after surgery will increase the chance of curing the disease and reduce the likelihood of developing incurable advanced disease.”

Abemaciclib works by targeting and inhibiting proteins in cancer cells which allow the cancer to divide and grow. It normally costs £2,950 for a packet of 56 150mg-tablets, but the manufacturer, Eli Lilly, has agreed an undisclosed discounted price for NHS England.

“Thanks in part to this latest deal struck by NHS England, NHS patients will be able to access another new targeted drug for a common and aggressive form of breast cancer,” said Prof Peter Johnson, the cancer director of NHS England.

“Abemaciclib, when used alongside a hormone therapy, offers a new, doubly targeted, treatment option, helping to increase the chances of beating the cancer for good, as well as meeting the NHS’s commitment to delivering improved cancer care under our long-term plan.”

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