Comment

Comment by Dr. Krishna Kumari Challa on Wednesday

If, as has been historically the case, men are used as a standard model for various disorders, researchers may miss out on critical insight.

While the AI tools could report differences in brain-cell organization, they could not reveal which sex was more likely to have which features.

According to the researchers, the team next plans to explore the development of sex-related brain structure differences over time to better understand environmental, hormonal, and social factors that could play a role in these  changes.

Deep Learning with Diffusion MRI as in vivo Microscope Reveals Sex-related Differences in Human White Matter Microstructure, Scientific Reports (2024).

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Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

Artificial intelligence tool detects sex-related differences in brain structure

Artificial intelligence (AI) computer programs that process MRI results show differences in how the brains of men and women are organized at a cellular level, a new study shows. These variations were spotted in white matter, tissue primarily located in the human brain's innermost layer, which fosters communication between regions.

The work appears in Scientific Reports.

Men and women are known to experience multiple sclerosis, autism spectrum disorder, migraines, and other brain issues at different rates and with varying symptoms. A detailed understanding of how biological sex impacts the brain is therefore viewed as a way to improve diagnostic tools and treatments. However, while brain size, shape, and weight have been explored, researchers have only a partial picture of the brain's layout at the cellular level.

The new study used an AI technique called machine learning to analyze thousands of MRI brain scans from 471 men and 560 women. Results revealed that the computer programs could accurately distinguish between biological male and female brains by spotting patterns in structure and complexity that were invisible to the human eye.

The findings were validated by three different AI models designed to identify biological sex using their relative strengths in either zeroing in on small portions of white matter or analyzing relationships across larger regions of the brain.

These findings provide a clearer picture of how a living, human brain is structured, which may in turn offer new insight into how many psychiatric and neurological disorders develop and why they can present differently in men and women.

For the research,  researchers started by feeding AI programs existing data examples of brain scans from healthy men and women and also telling the machine programs the biological sex of each brain scan. Since these models were designed to use complex statistical and mathematical methods to get "smarter" over time as they accumulated more data, they eventually "learned" to distinguish biological sex on their own. Importantly, the programs were restricted from using overall brain size and shape to make their determinations.

According to the results, all of the models correctly identified the sex of subject scans between 92% and 98% of the time. Several features in particular helped the machines make their determinations, including how easily and in what direction water could move through brain tissue.

These results highlight the importance of diversity when studying diseases that arise in the human brain.

Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

To determine how each of the viral serotypes affects the risk of severe disease, the researchers analyzed viral genetic data. The team also studied cases of patients hospitalized for dengue to determine which viral subtype caused their infections. Researchers gathered data from 21 years of dengue surveillance, ranging from 1994 to 2014, in a children's hospital in Bangkok, encompassing 15,281 individual cases. This allowed them to find repeat cases and each viral subtype in all infections.

Based on the pediatric patients' hospital records, researchers discovered a link between hospitalization and the order in which patients became infected with different dengue-virus serotypes. They were also able to determine which combinations of viral subtypes pointed to mild or severe forms of dengue. For instance, people who became infected with serotypes that were very similar, such as DENV-3 and DENV-4, or very different serotypes as in the case of DENV-1 and DENV-4, tended to have a lower risk of severe disease during the second infection.

Patients who were infected with serotypes that were only moderately different had a higher risk of severe symptoms in subsequent infections. The highest risk group in this category involved patients who had an initial infection with DENV-2 followed by a subsequent infection triggered by DENV-1.

The new research adds clarity to a disease risk that may seem paradoxical to the lay public. For example, most people infected with dengue virus for the first time develop extremely mild signs of the disease or none at all. But for those who do get sick, soaring fever, headache, body aches, nausea and rash are the primary symptoms, and they intensify in severe manifestations of the infection.

For more than a century a severe bout with dengue has been known as breakbone fever because of the intensity of the pain and accompanying muscle spasms.

The virus is carried in the tropics and subtropics by Aedes aegypti and Aedes albopictus mosquitoes, which are endemic in the dengue belt. But while the belt, which runs through latitudes 35-degrees North and 35-degrees South, has traditionally been home to dengue-carrying mosquitoes, the arthropods have been extending their range northward as global climate change intensifies, scientists say.

These findings suggest that immune imprinting helps determine dengue disease risk and provides a pathway to monitor the changing risk profile of populations and to quantifying risk profiles of candidate vaccines.

Lin Wang et al, Antigenic distance between primary and secondary dengue infections correlates with disease risk, Science Translational Medicine (2024). DOI: 10.1126/scitranslmed.adk3259

Part 3

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Comment by Dr. Krishna Kumari Challa on Wednesday

The team also underscored how dengue, a pernicious tropical malady, can be understood within the context of other common viral diseases that circle the globe.

The ability of viruses, such as SARS-CoV- 2 and influenza, to continuously change their genetic structure in response to the selective pressure of population immunity complicates control efforts.

In the case of dengue virus, an arbovirus that infects more than 100 million people each year, the situation is even more complex. Individuals with high dengue virus antibody titers are protected from infection and developing severe disease.

However, individuals with sub-neutralizing antibody titers have been shown to have the highest risk of severe disease, through multiple hypothesized mechanisms including antibody-dependent enhancement.

A dengue infection can be tricky. Some patients who have weathered an infection but get infected in a subsequent outbreak can have more severe symptoms the second time around. Yet, most research on repeat dengue infections has regarded each of the serotypes as no different from the other. An assessment of each serotype's genetic differences was needed to provide a clearer picture of potential risks.

To develop that clearer picture, researchers studied each serotype in more than 15,000 patients' infections as a way to peel away much of the mystery surrounding why first-time dengue illnesses are traditionally milder than subsequent ones.

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

 Why subsequent bouts of dengue are worse than a first-time infection

A massive upsurge in dengue cases marked by multiple outbreaks is occurring worldwide and raising new questions about who is at elevated risk of severe forms of the mosquito-transmitted disease.

Incidence of the infection has increased by orders of magnitude throughout the so-called dengue belt, which encompasses Central and South America, Sub-Saharan Africa, Southeast Asia and swaths of the South Pacific, home to densely populated islands. Dengue, without question, is the most widespread and rapidly increasing vector-borne disease in the world, according to the World Health Organization.

The story is similar in other dengue-affected areas of the world where lapses in vector control have conspired with global climate change to create an explosion of bloodthirsty mosquitoes, swarms of them moving into regions once considered dengue-free. Only female mosquitoes feed on blood, they're in constant need of the nutrients in it to nurture their eggs.

Now, more than two decades of dengue surveillance  is answering a slew of questions at a time when the world needs guidance most.

Findings from the research have revealed how various subgroups—what virologists call subtypes—of the dengue virus influence future risk of severe infection. It has been known for years that those who become infected in subsequent outbreaks, after a usually mild bout with a first-time infection, are at significant risk of severe disease in later dengue exposures. New research finally has analyzed more than 15,000 cases to discern why that is so.

Writing in Science Translational Medicine, a global team of scientists has explained how the four dengue viral subtypes—DENV-1, 2, 3, and 4—influence the risk of repeated severe infections. The findings provide a new framework for disease monitoring and lay the foundation for vaccination strategies as the new dengue immunizations emerge.

Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

Researchers approached this problem in many different ways.

In the context of this study, the researchers effectively provided two lines of evidence. The first one is theoretical in essence. Specifically, we rely on so-called Markov Decision Processes (MDPs) to demonstrate that confidence-based control policies are quasi-optimal for a broad class of decisions."

After having identified the non-trivial quantitative properties of confidence-based control policies, the researchers set out to determine whether these properties can be found in empirical data gathered in experiments where humans completed decision-making tasks. The properties they specifically sought for included three-way interactions between the values of different options, decision times and the reported confidence in a decision.

In brief, they identified a minimal cognitive architecture for quasi-optimal decision control (in terms of how much effort is invested). Importantly, this architecture may generalize over most, if not all, kinds of decision types. This implies that a single brain system may operate decision control, irrespective of the type of decision.

 Juliette Bénon et al, The online metacognitive control of decisions, Communications Psychology (2024). DOI: 10.1038/s44271-024-00071-y.

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

A minimal cognitive architecture reproduces control of human decision-making processes

Neuroscientists and psychologists have been trying to pinpoint the processes behind human decision-making for decades. While their efforts led to numerous interesting insights, the intricacies of complex decision-making remain poorly understood.

Researchers at the Paris Brain Institute carried out a study aimed at better understanding how the human brain allocates its resources when making decisions. Their paper, published in Communications Psychology, introduces an architecture that operates the online metacognitive control of decisions (oMCD), a theoretical construct describing why and how the brain choses to stop of continue deliberating.

Past studies have found that humans do not always invest their maximum mental efforts when making decisions. This can lead to various widely documented errors and cognitive biases (i.e., recurring deviations from rational thinking).

So when making a decision, what determines the amount of mental effort we invest in decisions?

Previous behavioral research suggested that, for certain kinds of decisions (so-called 'evidence-based' decisions), this may be done by balancing decision confidence (which tends to increase with mental effort) with the cost of mental effort. This then triggered the question: can this work for all kinds of decisions?

To address this question, researchers should first demonstrate that a confidence-based control policy eventually yields mental effort investments resembling those of optimal control policies that are specific to different kinds of decisions. This was one of the primary objectives of this work.

Part 1

Comment by Dr. Krishna Kumari Challa on Tuesday

This New Plastic Disappears When You Don't Need It Anymore

The plastic that eats itself

Our reliance on plastic has become a huge problem, which is why researchers are excited about a new type of material – one that comes with built-in biodegrading capabilities, due to the bacterial spores living inside it. The new self-digesting plastic combines thermoplastic polyurethane (TPU) and Bacillus subtilis bacteria, which had to be engineered to survive the high temperatures involved in plastic production. By repeatedly exposing the spores to increasing levels of heat, the team of researchers behind this new work found that the bacteria could eventually cope with the temperatures of 135 degrees Celsius (275 degrees Fahrenheit) required to mix the bacterial spores and TPU together. Past efforts to find ways to degrade plastics, fast, have often sourced bacterial enzymes and fungi from soils and compost heaps where those microbes are naturally abundant. But this new material needs only the bacterial spores inside it, reawakened with some nutrients and moisture, to start breaking down.

https://www.nature.com/articles/s41467-024-47132-8

Comment by Dr. Krishna Kumari Challa on Tuesday

Greenhouse gas emissions from using basic stoves and deforestation from collecting wood also contribute hugely to global warming.

Switching to clean cooking methods, such as LPG or electric cooking, would save 1.5 billion tonnes of CO₂ a year by 2030—roughly the amount emitted by ships and planes last year, according to the IEA.

IEA also recommends strong national leadership as well as grassroots efforts to change social norms.

Source: AFP and other news agencies

Comment by Dr. Krishna Kumari Challa on Tuesday

Bid to end deadly cooking methods which stoke global warming

Fifty countries are meeting in France  today to discuss the lack of access to clean cooking methods worldwide which causes millions of deaths every year and fuels global warming.

Some 2.3 billion people across 128 countries breathe in harmful smoke when they cook on basic stoves or over open fires, according to an International Energy Agency (IEA)-African Development Bank (ADB) report that sounded the alarm last year.

It said 3.7 million people a year die prematurely from harmful cooking practices, with children and women most at risk.

The IEA said the "unprecedented" Paris gathering aims to be "a moment of changing the direction". The problem "touches on gender, it touches on forestry, it touches on climate change, it touches on energy, it touches on health.

A third of the world cooks with fuels which produce harmful fumes when burned, including wood, charcoal, coal, animal dung and agricultural waste.

They pollute indoor and outdoor air with fine particles that penetrate the lungs and cause multiple respiratory and cardiovascular problems, including cancer and strokes.

These cooking practices are the third highest cause of premature deaths in the world and the second highest in Africa. In young children , they are a major cause of pneumonia, experts say.

They also prevent women and children from accessing education or earning a wage, as they spend hours looking for fuel.

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