Day: January 21, 2021

Categories : New Compounds and TreatmentsTags :

Antifungal Compound Discovered in Ant Farms

On By ModernMedia

Researchers in Brazil have discovered an antifungal compound by bacteria living in ant farms, which may have medical applications.

In the fungal farms where attine ants tend as their food source, Pseudonocardia and Streptomyces bacteria produce metabolites which shield the crop against pathogens. Curiously, these metabolites vary across geographic locations.

Attine ants are a type of ant which grow and harvest fungus for food, and are only found in the Western Hemisphere. They first evolved from a common Amazonian ancestor some 50 million years ago, giving rise to some 200 species of ants spread across South and Central America, which share common farming practices. The bacteria at these farms have a symbiotic relationship where they defend against fungi such as Escovopsis in exchange for food.

These metabolites vary considerably, suggesting a fragmented history. Searching a number of ant nests spread across a large geographical area, the researchers discovered that two thirds of the Pseudonocardia strains were producing the same metabolite. They named this newly discovered metabolite attinimicin.The study was the first one where a common, specialised metabolite produced by ant-associated bacteria was found across geographic locations.

Attinimicin inhibited fungal parasites while not harming the fungal crop, but only in the presence of iron. It proved as effective in treating Candida albicans infections in mice as a clinically used azole-containing antifungal. This means that the metabolite could have clinical applications. Attinimicin was shown to have a similar structure to two other metabolites produced by Streptomyces, suggesting the responsible genes have a common evolutionary origin.

Source: News-Medical.Net

Journal information: Fukuda, T.T.H., et al. (2021) Specialized Metabolites Reveal Evolutionary History and Geographic Dispersion of a Multilateral Symbiosis. ACS Central Science. doi.org/10.1021/acscentsci.0c00978.

Categories : AntibioticsTags :

Prevalence of Antibiotic Resistance is Underestimated

On By ModernMedia

Antibiotic resistance to pathogenic bacteria in humans has spread farther than expected, as it has been discovered that bacteria can swap DNA far more readily than thought possible.

A growing threat, antibiotic resistance has emerged faster than thought possible. Some 33 000 deaths have occurred to antibiotic resistant infections in Europe alone, and finding new antibiotics or even alternatives are a top research priority. Totally different strains of bacteria can swap genetic information through the use of containers called plasmids. Plasmids are small containers of DNA which are kept outside of their chromosomes. When two bacteria come into contact, they can copy plasmids to one another in a process called conjugation (also known as “bacterial sex“). This is the most important means by which bacteria spread antibiotic resistance.

“In recent years, we’ve seen that resistance genes spread to human pathogens to a much greater degree than anyone expected,” said Jan Zrimec, a researcher in systems and synthetic biology at the Chalmers University of Technology. “Many of the genes appear to have originated in a wide array of bacterial species and environments, such as soil, water, and plant bacteria.

“This has been difficult to explain because although conjugation is very common, we’ve thought that there was a distinct limitation for which bacterial species can transfer plasmids to each other. Plasmids belong to different mobility groups or MOB groups, so they can’t transfer between just any bacterial species.”

Among his developments, he has written an algorithm that can sift through substantial amounts of plasmid DNA to pick out sections of DNA which are necessary for conjugation (known as oriT regions, where the enzyme relaxase can bind to and snip out DNA). This algorithm can then sort the plasmids into groups based on their oriT regions. His new method differs from the standard one because it analyses oriT regions by their physiochemical properties instead of searching DNA for the enzyme sequence for relaxase, or the point where it can bind to. This method is less time-consuming and resource intensive than the standard one.

Previously, it was thought that a plasmid had to have both the relaxase enzyme and the oriT sequence to bind to, but a bacterial cell can have an oriT region for conjugation to occur. With his new algorithm, he has been able to explore the DNA of 4600 plasmids from different bacteria found in nature.
– There may be eight times as many oriT regions than those discovered with standard methods.
– There may be twice as many mobile plasmids as previously known.
– There also may be twice as many bacterial species with mobile plasmids as previously known.
– More than half the plasmids have an oriT group matching to an enzyme for conjugation from a plasmid that already been classified in a different MOB group. This means that they could be transferred from a different plasmid in the same cell.

The last finding suggests that there may be far greater interchange between bacteria than had been previously been believed.

“This has been a major limitation of the research field up to now,” Zrimec said. “I hope that the methods will be able to benefit large parts of the research into antibiotic resistance, which is an extremely interdisciplinary and fragmented area. The methods can be used for studies aiming to develop more effective limitations to antibiotic use, instructions for how antibiotics are to be used, and new types of substances that can prevent the spread of resistance genes at the molecular level.”

Source: News-Medical.Net

Journal information: Zrimec, J. (2021) Multiple plasmid origin‐of‐transfer regions might aid the spread of antimicrobial resistance to human pathogens. MicrobiologyOpen.doi.org/10.1002/mbo3.1129.

Categories : Implants and ProsthesesTags :

New Type of Corneal Implant Fuses into the Eye

On By ModernMedia

A new type of artificial cornea has been successfully implanted into an elderly patient, who demonstrated recovered sight the day after his surgery.

When the cornea is damaged by disease or injury, blindness can result, necessitating a cornea transplant. Artificial corneas are a much sought-after technology, as the normal treatment for a damaged cornea is to seek a transplanted replacement. However, for every 70 corneas sought, there is only a single donor cornea. CorNeat Vision is set to offer the first commercially available synthetic cornea implant, the KPro.

The new cornea has a clear centre section, surrounded by a white skirt consisting of electrospun nanofibres. Electrospun nanofibres have already found application in many medical applications, such as a new kind of translucent burn dressing. This skirt’s nanofibre material allows fibroblasts and collagen to infiltrate its structure, allowing full integration within a few weeks of surgery. This biomimetic technology results in faster healing times, the ability to use fully synthetic implants and is fully scalable as it does not rely on any harvested tissue.

The implantation procedure involves removing the epithelium covering the cornea, marking the location of where the artificial cornea implant should go, removing the cornea and then suturing its replacement into position.

Only a day after his surgery, the first recipient of this new artificial cornea was able to make out the faces of his relatives and read numbers off of a chart.

Source: Medical Xpress

Categories : COVID Expert OpinionTags :

UCT Expert Talks COVID and Warns of Third Wave

On By ModernMedia

If South Africa does not pursue a rapid vaccination programme to achieve herd immunity, it may face a third wave as a consequence, warned a leading local expert.

Professor Marc Mendelson of UCT’s Division of Infectious Diseases and HIV Medicine at Groote Schuur Hospital made these statements while speaking during a virtual Summer School lecture on Saturday, titled “COVID-19 Insights and Lessons”.

“Without rapid vaccination of at least two thirds of the population, we [South Africa] are not going to get to population immunity, and without that, we will see another wave,” Mendelson warned.

However, he emphasised that much had been accomplished in the battle against COVID. “It is associated with a scientific endeavour that we have never seen before. We’re definitely better off a year down the line, but there are a huge number of things that we need to answer. As a country we still face deep problems with severe issues around vaccine strategy, and we haven’t even talked about vaccine denial,” he said.

Criticism has been directed at the South African government because of its failure to start a vaccination programme, despite its huge case load and status as Africa’s most wealthy nation. A leaked phone call from a Pfizer executive has only added to this, as it was revealed that for months SA health officials had not been responding to requests for vaccine discussions.

Regarding COVID transmission, he said that the virus resided in the upper respiratory tract as well as the lungs, and that it could be expelled in aerosol droplets. The clinical and epidemiological evidence suggested that larger, heavier droplets carried the virus.

“The household infection rates were high. A very large number of cases, the vast majority [in fact], were within families in close proximity [to one another]. This, epidemiologically, suggests that large droplets play a role in transmission.

“If you want to reduce transmission from large droplets, then you need to increase the distance you are from someone. Also, because droplets drop onto surfaces … you will need to clean surfaces and wash your hands well. This is the science behind the use of masks, handwashing, social distancing and ventilation.”

However, he added that a number of studies had found the virus in remote corners of hospitals at a distance from patients, suggesting that it had been carried there by smaller, aerosolised particles.

“If you want to reduce aerosols, one way of doing that is to improve ventilation. The more the air is changed, the [quicker] it will dilute small droplets,” he said.

Source: University of Cape Town

Categories : Uncategorized

South African 510Y.V2 COVID Strain Resistant to Previous Antibodies

On By ModernMedia

Results from a National Institute of Communicable Diseases (NICD) study shows that immunity gained against the initial strains of SARS-CoV-2 is blunted against the new 501Y.V2 strain that originated in South Africa.

The new variants which are more transmissible have mutations to their spike proteins that give the coronavirus its distinctive shape—and to which immune antibodies bind. Scientists have been concerned that the new strains may also escape vaccine containment, especially the E484K mutation, which has been observed in new strains found in Brazil and South Africa.

In the study, which is awaiting peer review, researchers took plasma from patients who had recovered from the original COVIDs, and tested those samples against the 501Y.V2 virus variant to measure antibody reaction. The virus was more resistant to these antibodies, which had been built up from previous infections. “Here we show that the 501Y.V2 lineage, which contains nine spike mutations and rapidly emerged in South Africa during the second half of 2020, is largely resistant to neutralising antibodies elicited by infection with previously circulating lineages,” said the researchers.

“This suggests that, despite the many people who have already been infected with SARS-CoV-2 globally and are presumed to have accumulated some level of immunity, new variants such as 501Y.V2 pose a significant re-infection risk.”

The researchers noted that these findings may have implications for those treated with convalescent plasma (a donor programme for which  is run by the South African National Blood Service). Additionally, there were “implications” for those vaccines that were developed based around an immune response to the virus’ spike proteins.

Vaccines may therefore have to be adjusted to account for the new spike mutation in order to retain effectiveness against variants possessing that mutation. The developers of the Oxford/AstraZeneca vaccine are already preparing to proactively adjust their vaccines to account for the new strains emerging around the world.

Commenting to the Science Media Centre, Lames Naismith, Director of the Rosalind Franklin Institute said that it was “not good news but it’s not unexpected.

“He said that real-world immune responses are more complicated than those of the blood plasma neutralising antibodies. “The vaccines do stimulate very strong responses, immunity is a sliding scale, it’s not an on/off switch,” he explained.

In another study posted online, it was reported that antibodies from recovered patients did mostly protect against B.1.1.7, the variant that originated in the UK.

“Our results suggest that the majority of vaccine responses should be effective against the B.1.1.7 variant,” concluded researchers from one the UK/Netherlands studies.

A separate study showed that the Pfizer/BioNTech vaccine also appeared to confer protection against that variant as well, with the authors concluding that it was “unlikely” that the B.1.1.7 variant could escape vaccine protection.

Source: Medical Xpress