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Comment by Dr. Krishna Kumari Challa on July 13, 2021 at 10:01am

Researchers unlock behavior of rare cells that evade antibiotics by 'playing dead'

Researchers have developed a new microfluidic platform to track a very rare type of cell that can survive antibiotic treatments. The results have important implications for microbiologists learning about the cellular control of bacterial physiology and for scientists looking to combat the emerging threat of antibiotic resistance bacteria that can lead to untreatable infections.

"Persister cells" are a very small subpopulation of cells that survive antibiotic treatment by staying dormant and then resume growth after the antibiotic has been removed. These cells are transient and are therefore harder to study and have no genetic changes, meaning that they cannot be identified using sequencing.

Since these "persister cells" are both rare and transient, a platform is needed to image cells over time with sufficiently large throughput. Now researchers from the University of Cambridge, Harvard Medical School and Harvard University have developed a platform designed to track more than 100,000 individual bacterial cells over hundreds of generations as they experience rounds of feast-and-famine cycles. An array of hundreds of thousands of traps are used to keep individual cells immobilized and infused with the contents from a growing culture—E. coli (Escherichia coli), normally found in the intestine, and Bacillus subtilis, commonly found in soil. A high-resolution microscope rapidly scans over each cell and tracks their fate over time. The results are reported in the journal Nature Microbiology.

Somenath Bakshi et al, Tracking bacterial lineages in complex and dynamic environments with applications for growth control and persistence, Nature Microbiology (2021). DOI: 10.1038/s41564-021-00900-4

https://phys.org/news/2021-07-behavior-rare-cells-evade-antibiotics...

Comment by Dr. Krishna Kumari Challa on July 13, 2021 at 9:47am

Carbon Capture

Comment by Dr. Krishna Kumari Challa on July 13, 2021 at 9:37am

Restoring touch in nerves damaged by injury

Tel Aviv University's new and groundbreaking technology inspires hope among people who have lost their sense of touch in the nerves of a limb following amputation or injury. The technology involves a tiny sensor that is implanted in the nerve of the injured limb, for example in the finger, and is connected directly to a healthy nerve. Each time the limb touches an object, the sensor is activated and conducts an electric current to the functioning nerve, which recreates the feeling of touch. The researchers emphasize that this is a tested and safe technology that is suited to the human body and could be implanted anywhere inside of it once clinical trials will be done.

The researchers developed a sensor that can be implanted on a damaged nerve under the tip of the finger; the sensor connects to another nerve that functions properly and restores some of the tactile sensation to the finger. This unique development does not require an external power source such as electricity or batteries. The researchers explain that the sensor actually works on frictional force: whenever the device senses friction, it charges itself.

The device consists of two tiny plates less than half a centimeter by half a centimeter in size. When these plates come into contact with each other, they release an electric charge that is transmitted to the undamaged nerve. When the injured finger touches something, the touch releases tension corresponding to the pressure applied to the device—weak tension for a weak touch and strong tension for a strong touch—just like in a normal sense of touch.

The researchers explain that the device can be implanted anywhere in the body where tactile sensation needs to be restored, and that it actually bypasses the damaged sensory organs. Moreover, the device is made from biocompatible material that is safe for use in the human body, it does not require maintenance, the implantation is simple, and the device itself is not externally visible.

Iftach Shlomy et al, Restoring Tactile Sensation Using a Triboelectric Nanogenerator, ACS Nano (2021). DOI: 10.1021/acsnano.0c10141

https://phys.org/news/2021-07-nerves-injury.html?utm_source=nwlette...

Comment by Dr. Krishna Kumari Challa on July 13, 2021 at 9:27am

Just 25 mega-cities produce 52% of the world's urban greenhouse gas emissions

In 2015, 170 countries worldwide adopted the Paris Agreement, with the goal limiting the average global temperature increase to 1.5°C. Following the agreement, many countries and cities proposed targets for greenhouse gas mitigation. However, the UNEP Emissions Gap Report 2020 shows that, without drastic and strict actions to mitigate the climate crisis, we are still heading for a temperature increase of more than 3°C by the end of the 21st century.

A new study published in the journal Frontiers in Sustainable Cities presents the first global balance sheet of greenhouse gasses (GHGs) emitted by major cities around the world. The aim was to research and monitor the effectiveness of historical GHG reduction policies implemented by 167 globally distributed cities that are at different developmental stages.

While only covering 2% of the Earth's surface, cities are big contributors to the climate crisis. But current urban GHG mitigation targets are not sufficient to achieve global climate change targets by the end of this century. 

The results showed that both developed and developing countries have cities with high total GHG emissions, but that megacities in Asia (such as Shanghai in China and Tokyo in Japan) were especially important emitters. The inventory of per capita emissions showed that cities in Europe, the US, and Australia had significantly higher emissions than most cities in developing countries. China, classified here as a developing country, also had several cities where per capita emissions matched those of developed countries. It is important to note that many developed countries outsource high carbon production chains to China, which increases export-related emissions for the latter.

Stationary energy—which includes emissions from fuel combustion and electricity use in residential and institutional buildings, commercial buildings, and industrial buildings—contributed between 60 and 80% of total emissions in North American and European cities. In one third of the cities, more than 30% of total GHG emissions were from on-road transportation. Meanwhile, less than 15% of total emissions came from railways, waterways, and aviation.

Lastly, the findings show that the levels of emissions increase and decrease varied between the cities over the study period.

Ting Wei et al, Keeping Track of Greenhouse Gas Emission Reduction Progress and Targets in 167 Cities Worldwide, Frontiers in Sustainable Cities (2021). DOI: 10.3389/frsc.2021.696381

https://phys.org/news/2021-07-mega-cities-world-urban-greenhouse-ga...

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Comment by Dr. Krishna Kumari Challa on July 13, 2021 at 9:22am

Protein appears to prevent tumor cells from spreading via blood vessels

Researchers have identified a specialized protein that appears to help prevent tumor cells from entering the bloodstream and spreading to other parts of the body.

They have discovered that this protein, TRPM7, senses the pressure of fluid flowing in the circulation and stops the cells from spreading through the vascular system. they also found that metastatic tumour  cells have markedly reduced levels of this sensor protein, and that is why they efficiently enter into the circulation rather than turning away from fluid flow.

The findings, published in Science Advances, help shed light on a little-understood part of metastasis called intravasation, when cancer cells that have separated from a primary tumour enter the circulation in order to travel to other parts of the body and establish colonies.

The researchers further show that artificially increasing the expression of TRPM7 in tumor cells may help stop intravasation—and ultimately metastasis—in its tracks.

Christopher L. Yankaskas et al, The fluid shear stress sensor TRPM7 regulates tumor cell intravasation, Science Advances (2021). DOI: 10.1126/sciadv.abh3457

https://medicalxpress.com/news/2021-07-protein-tumor-cells-blood-ve...

Comment by Dr. Krishna Kumari Challa on July 12, 2021 at 10:45am

90-year-old woman infected with UK and South African COVID-19 variants at the same time

Researchers in Belgium report on the case of a 90-year-old woman who was simultaneously infected with two different variants of concern (VOCs) of COVID-19, in a Case Report being presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) held online this year.

On March 3 2021, the woman, whose medical history was unremarkable, was admitted to the OLV Hospital in the Belgian city of Aalst after a spate of falls. She tested positive for COVID-19 on the same day. She lived alone and received nursing care at home, and had not been vaccinated against COVID-19.

Initially, there were no signs of respiratory distress and the patient had good oxygen saturation. However, she developed rapidly worsening respiratory symptoms, and died five days later.

When the patient's respiratory sample was tested for VOCs with PCR, they discovered that she had been infected by two different strains of the virus—one which originated in the UK, known as B.1.1.7 (Alpha), and another that was first detected in South Africa (B.1.351; Beta).

The presence of both strains was confirmed by PCR on a second respiratory sample, by sequencing of the S-gene and by whole genome sequencing.

"This is one of the first documented cases of co-infection with two SARS-CoV-2 variants of concern.

Both these variants were circulating in Belgium at the time, so it is likely that the lady was co-infected with different viruses from two different people. 

In January 2021, scientists in Brazil reported that two people had been simultaneously infected with two different strains of the coronavirus—the Brazilian variant known as B.1.1.28 (E484K) and a novel variant VUI-NP13L, which had previously been discovered in Rio Grande do Sul. But the study has yet to be published in a scientific journal [1]. Previous research has reported people infected with different influenza strains [2].

Whether the co-infection of the two variants of concern played a role in the fast deterioration of the patient is difficult to say.

 [1] Pervasive transmission of E484K and emergence of VUI-NP13L with evidence of SARS-CoV-2 co-infection events by two different lineages in Rio Grande do Sul, Brazil | medRxiv www.medrxiv.org/content/10.110 … 021.01.21.21249764v1

[2] Natural co-infection of influenza A/H3N2 and A/H1N1pdm09 viruses resulting in a reassortant A/H3N2 virus - ScienceDirect www.sciencedirect.com/science/ … ii/S1386653215007404

ECCMID ABSTRACT 04978: Case report: a 90-year-old lady infected with two CoVID-19 VoCs: 20I/501Y.V1 and 20H/501Y.V2

https://medicalxpress.com/news/2021-07-year-old-woman-infected-uk-s...

Comment by Dr. Krishna Kumari Challa on July 12, 2021 at 10:35am

Resistance to last-resort antibiotic may be passing between pet dogs and their owners

The dangerous mcr-1 gene, which provides resistance to the last-resort antibiotic colistin, has been found in four healthy humans and two pet dogs. In two cases, both dog and owner were harbouring the gene, according to new research being presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) held online this year.

Since first being reported in China in 2015, the mcr-1 gene has been found in various people and animals around the world. It confers resistance to colistin, an antibiotic of last resort used to treat infections from some bacteria resistant to all other antibiotics. The nightmare scenario that could emerge is mcr-1 combining with already drug-resistant bacteria to create a truly untreatable infection.

The study showed that eight dogs out of the 102 pets (7.8%) and four humans out of 126 (3.2%) harboured bacteria with the mcr-1 gene. Three of the dogs were healthy, four had SSTIs and one had a UTI. None of the cats were carrying the gene.

Further analysis showed that the bacteria isolated from all 12 samples that were mcr-1 positive were resistant to multiple antibiotics.

In two households with dogs with SSTIs, the mcr-1 gene was found in both dog and owner. Genetic analysis of the samples suggested that in one of these two cases, the gene had been transmitted between pet and owner.While transmission in both directions is possible, it is thought that in this case the gene passed from dog to human, say the researchers.

The owners did not have infections and so did not need treatment. The sick dogs were successfully treated.

The researchers say their results show that the mcr-1 gene can be transmitted between dogs and their owners. This raises concerns that pets can act as reservoirs of the gene and so aid the spread of resistance to precious last-line antibiotics.

The study was presented at the ongoing European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) taking place online between July 9 and 12.

Source: EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

https://medicalxpress.com/news/2021-07-resistance-last-resort-antib...

Comment by Dr. Krishna Kumari Challa on July 12, 2021 at 9:23am

Heritable Epigenetics: The right combination of parents can turn a gene off indefinitely

Evidence suggests that what happens in one generation—diet, toxin exposure, trauma, fear—can have lasting effects on future generations. Scientists think these effects result from epigenetic changes that occur in response to the environment and turn genes on or off without altering the genome or DNA sequence.

But how these changes are passed down through generations has not been understood, in part, because scientists have not had a simple way to study the phenomenon. A new study by researchers at the University of Maryland provides a potential tool for unraveling the mystery of how experiences can cause inheritable changes to an animal's biology. By mating nematode worms, they produced permanent epigenetic changes that lasted for more than 300 generations. The research was published on July 9, 2021, in the journal Nature Communications.

With their new findings, the researchers now think  some genes could be more vulnerable to permanent epigenetic change while other genes recover within a few generations. Although studies in worms are not the same as in humans, the research provides a window into biological processes that are likely shared, at least in part, by all animals.

"Mating can initiate stable RNA silencing that overcomes epigenetic recovery," Nature Communications (2021). DOI: 10.1038/s41467-021-24053-4

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The research team found while breeding nematode worms that some matings led to epigenetic changes in offspring that continued to be passed down through as many generations as the scientists continued to breed them. This discovery will enable scientists to explore how epigenetic changes are passed to future generations and what characteristics make genes susceptible to permanent epigenetic changes.

They found that there are these RNA-based signals controlling gene expression. Some of these signals silence the gene and some of them are protective signals that prevent silencing. These signals are duking it out as the offspring develop. When the gene comes from the mother, the protective signal always wins, but when the gene comes from the father, the silencing signal almost always wins.

When the silencing signal wins, the gene is silenced for good, or for at least 300 generations, which is how long these researchers followed their laboratory-bred worms. Previous examples of epigenetic changes were more complex or they did not last more than a couple of generations. The researchers don't yet know why the silencing signal only wins some of the time, but this new finding puts them in a much better position to explore the details of epigenetic inheritance than ever before.

While they've found a set of genes that can be silenced almost permanently, most other genes are not affected the same way.

https://phys.org/news/2021-07-combination-parents-gene-indefinitely...

Comment by Dr. Krishna Kumari Challa on July 12, 2021 at 8:27am

Comment by Dr. Krishna Kumari Challa on July 12, 2021 at 8:25am

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