Day: February 25, 2022

Categories : Diseases, Syndromes and ConditionsTags :

Study Reveals the Intricacy of C. Diff’s Armour

On By ModernMedia
The spectacular structure of the protective armour of superbug C. difficile has been revealed for the first time showing the close-knit yet flexible outer layer – like chain mail. This assembly prevents molecules getting in and provides a new target for future treatments, according to the scientists at Newcastle, Sheffield and Glasgow Universities who have uncovered it. Credit: Newcastle University, UK

The spectacular structure of the protective armour of C. difficile has been revealed for the first time showing the close-knit yet flexible outer layer – like a mediaeval knight’s chain mail.

This tight arrangement keeps molecules from getting in and provides a new target for future treatments, according to the scientists who have uncovered it.

Published in Nature Communications, the team of scientists outlined the structure of the main protein, SlpA, that forms the links of the chain mail and how they link up to form a pattern and create this flexible armour.
One of the many ways that Clostridioides difficile has to protect itself from antibiotics is a special layer that covers the cell of the whole bacteria – the surface layer or S-layer. This flexible armour protects against the entry of drugs or molecules released by our immune system to fight bacteria.

Using a combination of X-ray and electron crystallography, the team determined the structure of the proteins and their arrangement.

Corresponding author and lead researcher Dr Paula Salgado said: “I started working on this structure more than 10 years ago, it’s been a long, hard journey but we got some really exciting results! Surprisingly, we found that the protein forming the outer layer, SlpA, packs very tightly, with very narrow openings that allow very few molecules to enter the cells. S-layer from other bacteria studied so far tend to have wider gaps, allowing bigger molecules to penetrate. This may explain the success of C.diff at defending itself against the antibiotics and immune system molecules sent to attack it.

“Excitingly, it also opens the possibility of developing drugs that target the interactions that make up the chain mail. If we break these, we can create holes that allow drugs and immune system molecules to enter the cell and kill it.”

Antimicrobial resistance (AMR), a growing problem, was declared by WHO as one of the top 10 global public health threats facing humanity.
One of the many bacteria that have evolved resistance to antibiotics, C. diff infects the human gut and is resistant to all but three current drugs. Antibiotics only compound the problem, as the good bacteria in the gut are killed alongside those causing an infection and, as C. diff is resistant, it can grow and cause diseases ranging from diarrhoea to death due to massive lesions in the gut. Since the only way to treat C.diff is to take antibiotics, it creates a vicious cycle of recurrent infections.

This knowledge could lead to the development of C. diff specific drugs that break the protective layer, creating holes to allow drug molecules to penetrate and kill the cell.

Dr Rob Fagan, who helped carry out the electron crystallography work, said: “We’re now looking at how our findings could be used to find new ways to treat C. diff infections such as using bacteriophages to attach to and kill C. diff cells – a promising potential alternative to traditional antibiotic drugs.”

Source: EurekAlert!

Categories : Cardiovascular Disease NeurologyTags :

Antiepileptics in Comatose Cardiac Arrest Survivors are Ineffective, Study Shows

On By ModernMedia
Image by Falkurian Design on Unsplash

A large scale study of comatose intensive care (ICU) patients admitted after cardiac arrest and resuscitation has shown that antiepileptics to treat epilepsy-like brain activity has no effect, and may even prolong ICU stay.

Following a cardiac arrest and resuscitation, patients may need an ICU stay, and are in a coma. By that stage, the cardiac arrest may have damaged the brain to such an extent that half of the patients will not recover from coma. The other half will also have permanent damage, for example of memory functions. It is extremely difficult to predict if a patient will awaken and what their prognosis is, so clinicians make use of EEG (electroencephalography).

In 10–20% of the patients admitted to the ICU after cardiac arrest and resuscitation, there are signs of brain activity that appear similar to epilepsy: unlike an attack this activity is continuous. For a long time, it was unclear if anti-epileptic medication could help better recovery. As a result, some patients received this medication and some did not.

Now, a large-scale study done between 2014 and 2021 on 172 patients has proven that this medication is ineffective: it does not help recovery, even necessitating a longer ICU stay. The researchers, led by Professor Jeannette Hofmeijer of the University of Twente and Rijnstate Hospital in Arnhem, published their findings in the New England Journal of Medicine.

The conclusion from this study is that anti-epileptic medication does not lead to an improved recovery. The findings show that patients may need to stay longer at the ICU: for the patient an undesired situation, and it puts extra pressure on the health care system. 

Aside from patients who show continuous epileptic signals, a small group of patients show signs of a typical epileptic seizure: a short and heavy attack. In these situations, anti-epileptics could help, but this still needs further research.

“Although the outcome of the trial may be disappointing in terms of chances of recovery, it also takes away uncertainties from the family. The signals point at serious brain damage that would lead to a much longer stay at the ICU,” said Prof Hofmeijer.

Source: University of Twente

Categories : Cardiovascular DiseaseTags :

High CAC and Lipoprotein(a) Scores Greatly Worsen CVD Risk

On By ModernMedia
Healthy red blood cells. Source: NIH

Having both a high lipoprotein(a) and high coronary artery calcium score (CAC) results in a 22% risk of heart attack or stroke over the following 10 years, nearly double the risk of having either condition alone. These are the findings are from a study published in the Journal of the American College of Cardiology (JACC).

Two decades ago, it was recognised that lipoprotein(a) (Lp(a)) concentrations were elevated in patients with cardiovascular disease (CVD). However Lp(a) was not yet proven to be important due to a lack of both Lp(a)-lowering therapy and evidence that reducing Lp(a) levels improves CVD risk. Recent research has added to the evidence 

“We are hopeful that by making the connection between Lp(a) and CAC as dual risk drivers, we can raise awareness in the medical community and improve earlier heart attack prevention for these patients,” said cardiologist Parag Joshi, MD, Associate Professor of Internal Medicine at UT Southwestern. “Our data may also expedite the development of treatments designed specifically for this high-risk population.”

About one sixth of people in the U.S. have high Lp(a), driven largely by genetics. Coronary artery calcium (CAC) is a marker of plaque deposits around the heart. 

Cardiology researchers confirmed the Lp(a) and CAC connection by comparing data from two landmark cardiovascular trials, the Dallas Heart Study, an ongoing comprehensive study of 6000 diverse and heart-healthy patients conducted from 2000 to present, and the Multi-Ethnic Study of Atherosclerosis (MESA) 6000-participant study investigating early-stage atherosclerosis.

The researchers found that participants with combined high Lp(a) and high CAC had a 22% 10-year risk of heart attack or stroke, compared with a 10-15% 10-year risk in patients who had either risk factor alone.

The team identified three distinct risk-related trends:

  • High Lp(a), high CAC: These individuals face the highest 10-year risk of heart attack or stroke.
  • High Lp(a), zero CAC: 10-year heart attack and stroke risk is low when there is no CAC, even if Lp(a) is high.
  • Low Lp(a), high CAC: 10-year heart attack or stroke risk is higher than average but lower than with high LP(a) and high CAC combined.

“Establishing the connection between Lp(a) and CAC means we can move to the important next phase of research, which will be defining and personalizing early screening protocols to identify patients at high risk of heart attack,” said Dr Joshi. “With further research, this could mean selectively scanning patients with high Lp(a) for their CAC score, and studying therapies specifically designed to reduce Lp(a) among patients with high CAC.”

Source: UT Southwestern Medical Center