Comment

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 9:36am

Dentists are pulling 'healthy' and treatable teeth to profit from implants, experts warn

Dental implants have been used for more than half a century to surgically replace missing or damaged teeth with artificial duplicates, often with picture-perfect results. While implant dentistry was once the domain of a small group of highly trained dentists and specialists, tens of thousands of dental providers now offer the surgery and place millions of implants each year.

Amid this booming industry, some implant experts worry that many dentists are losing sight of dentistry's fundamental goal of preserving natural teeth and have become too willing to remove teeth to make room for expensive implants, according to a months-long investigation by KFF Health News and CBS News.

In interviews, 10 experts said they had each given second opinions to multiple patients who had been recommended for mouths full of implants that the experts ultimately determined were not necessary.

Separately, lawsuits filed have alleged that implant patients  have experienced painful complications that have required corrective surgery, while other lawsuits alleged dentists at some implant clinics have persuaded, pressured, or forced patients to remove teeth unnecessarily.

The experts warn that implants, for a single tooth or an entire mouth, expose patients to costs and surgery complications, plus a new risk of future dental problems with fewer treatment options because their natural teeth are forever gone.

There are many cases where teeth're perfectly fine, and they're being removed unnecessarily.

2024 KFF Health News. Distributed by Tribune Content Agency, LLC.

https://medicalxpress.com/news/2024-11-dentists-healthy-treatable-t...

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Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 9:27am

Biologists discover how plants evolved multiple ways to override genetic instructions

Biologists  have discovered the origin of a curious duplication that gives plants multiple ways to override instructions that are coded into their DNA. This research could help scientists exploit a plant's existing systems to favor traits that make it more resilient to environmental changes, like heat or drought stress.

This new research focuses on DNA methylation, a normal biological process in living cells wherein small chemical groups called methyl groups are added to DNA. This activity controls which genes are turned on and off, which in turn affects different traits—including how organisms respond to their environments.

Part of this job involves silencing, or turning off, certain snippets of DNA that move around within an organism's genome. These so-called jumping genes, or transposons, can cause damage if not controlled. The entire process is regulated by enzymes, but mammals and plants have developed different enzymes to add methyl groups.

Mammals only have two major enzymes that add methyl groups in one DNA context, but plants actually have multiple enzymes that do that in three DNA contexts.

The question is—why do plants need extra methylation enzymes?

Certain genes or combinations of genes are contributing to certain features or traits. If researchers find precisely how they are regulated, then they can find a way to innovate  technology for crop improvement.

Jianjun Jiang et al, Substrate specificity and protein stability drive the divergence of plant-specific DNA methyltransferases, Science Advances (2024). DOI: 10.1126/sciadv.adr2222. www.science.org/doi/10.1126/sciadv.adr2222

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Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 9:14am

Pathogens that cling to microplastics may survive wastewater treatment

Wastewater treatment fails to kill several human pathogens when they hide out on microplastics in the water, reports a study published November 6, 2024 in the open-access journal PLOS ONE.

Wastewater treatment plants are designed to remove contaminants from wastewater, but microplastics persist and can become colonized by a sticky microbial biofilm. Previous research has suggested that these microbial communities, called plastispheres, include potential pathogens, and thus might pose a risk to human health and the environment when treated wastewater and sludge are released.

In the new study, researchers identified food-borne pathogens in plastispheres living on three types of plastic in wastewater. They cultured the microorganisms and used genetic techniques to understand the diversity and members of the plastisphere communities.

The team found evidence of pathogenic bacteria and viruses, including Listeria monocytogenes, Escherichia coli, norovirus and adenovirus. They also successfully grew Klebsiella pneumoniae and Acinetobacter spp. from raw and treated wastewater, indicating that the plastisphere biofilms likely protect the pathogens from wastewater treatment.

These findings highlight the potential of plastispheres to harbor and spread pathogens, which poses a challenge to safely reusing wastewater. Without efficient wastewater treatment and plastic waste management, wastewater could act as a vehicle for transferring plastic-associated pathogens into the food chain.

The researchers emphasize that continued research and innovation are essential to remove microplastics—and their pathogens—from wastewater.

 Wastewater-associated plastispheres: A hidden habitat for microbial pathogens?, PLOS ONE (2024). DOI: 10.1371/journal.pone.0312157

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 9:07am

Waste Heat to Electricity

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 8:52am

Climate change is contributing to drought in the American West even without rainfall deficits, scientists find

Higher temperatures caused by anthropogenic climate change made an ordinary drought into an exceptional drought that parched the American West from 2020–2022. A study by UCLA and National Oceanic and Atmospheric Administration climate scientists has found that evaporation accounted for 61% of the drought's severity, while reduced precipitation only accounted for 39%. The research found that evaporative demand has played a bigger role than reduced precipitation in droughts since 2000, which suggests droughts will become more severe as the climate warms.

Research has already shown that warmer temperatures contribute to drought, but this is the first study that actually shows that moisture loss due to demand is greater than the moisture loss due to lack of rainfall," say the authors of a study published in Science Advances.

For generations, drought has been associated with drier-than-normal weather. This study further confirms we've entered a new paradigm where rising temperatures are leading to intense droughts, with precipitation as a secondary factor.

A warmer atmosphere holds more water vapour before the air mass becomes saturated, allowing water to condense and precipitation to form. In order to rain, water molecules in the atmosphere need to come together. Heat keeps water molecules moving and bouncing off each other, preventing them from condensing. This creates a cycle in which the warmer the planet gets, the more water will evaporate into the atmosphere—but the smaller fraction will return as rain. Therefore, droughts will last longer, cover wider areas and be even drier with every little bit that the planet warms.

 Yizhou Zhuang et al, Anthropogenic warming has ushered in an era of temperature-dominated droughts in the western United States, Science Advances (2024). DOI: 10.1126/sciadv.adn9389

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 8:43am

Researchers show astrocytes in the brain play a role in memory retrieval

A study published in Nature by researchers  changes the way we understand memory. Until now, memories have been explained by the activity of brain cells called neurons that respond to learning events and control memory recall.

The present work  expanded this theory by showing that non-neuronal cell types in the brain called astrocytes—star-shaped cells—also store memories and work in concert with groups of neurons called engrams to regulate storage and retrieval of memories.

The researchers show that during learning events, such as fear conditioning, a subset of astrocytes in the brain expresses the c-Fos gene. Astrocytes expressing c-Fos subsequently regulate circuit function in that brain region.

The c-Fos-expressing astrocytes are physically close with engram neurons.

Furthermore, the researchers found that engram neurons and the physically associated astrocyte ensemble are also functionally connected. Activating the astrocyte ensemble specifically stimulates synaptic activity or communication in the corresponding neuron engram. This astrocyte-neuron communication flows both ways; astrocytes and neurons depend on each other.

The team also found that astrocytes activated by learning events have elevated levels of the NFIA protein, and preventing NFIA production in these astrocytes suppresses memory recall. Importantly, this suppression is memory specific.

These findings speak to the nature of the role of astrocytes in memory.

Benjamin Deneen, Learning-associated astrocyte ensembles regulate memory recall, Nature (2024). DOI: 10.1038/s41586-024-08170-w. www.nature.com/articles/s41586-024-08170-w

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 8:26am

Those featured circles, ecDNAs, are small and often contain a few genes on their circular DNA. Frequently, these genes are cancer-associated genes called oncogenes. When a cancer cell contains multiple oncogene-encoding ecDNAs, they can supercharge the cell's growth and allow it to evade internal checkpoints meant to regulate cell division.

The ecDNAs also sometimes encode genes for proteins that can tamp down the immune system's response to a developing cancer—further advantaging tumor growth.
Until recently, it was thought that only about 2% of tumors contained meaningful amounts of ecDNA. But in 2017, research showed that the small circles were widespread and likely to play a critical role in human cancers.

In 2023, researchers further showed that their presence jumpstarts a cancerous transformation in precancerous cells.

In the first of the three papers researchers built on 2017 finding by analyzing the prevalence of ecDNA in nearly 15,000 cancer patients and 39 tumor types.

They found that 17.1% of tumors contained ecDNA, that ecDNA was more prevalent after targeted therapy or cytotoxic treatments like chemotherapy, and that the presence of ecDNA was associated with metastasis and poorer overall survival.

The researchers also showed that the circles can contain not just cancer-driving oncogenes and genes that modulate the immune response, but also that others can contain only DNA sequences called enhancers that drive the expression of genes on other circles by linking two or more ecDNAs together.
The ecDNAs with enhancer elements don't confer any benefit to the cell on their own; they have to work with other ecDNAs to spur cancer cell growth. If looked at through a conventional lens, the presence of ecDNAs that solely encode enhancers wouldn't seem to be a problem. But the teamwork and physical connection between different types of circles is actually very important in cancer development."
Through these studies researchers learned critical lessons about which cancer patients are affected and what genes or DNA sequences are found in ecDNAs. They identified the genetic backgrounds and mutational signatures that give them clues as to how cancers originate and thrive.

Howard Chang, Coordinated inheritance of extrachromosomal DNAs in cancer cells, Nature (2024). DOI: 10.1038/s41586-024-07861-8. www.nature.com/articles/s41586-024-07861-8

Paul Mischel, Enhancing transcription–replication conflict targets ecDNA-positive cancers, Nature (2024). DOI: 10.1038/s41586-024-07802-5. www.nature.com/articles/s41586-024-07802-5

Charles Swanton, Origins and impact of extrachromosomal DNA, Nature (2024). DOI: 10.1038/s41586-024-08107-3. www.nature.com/articles/s41586-024-08107-3

Part2

Comment by Dr. Krishna Kumari Challa on November 7, 2024 at 8:19am

Cracking the code of DNA circles in cancer: Scientists uncover potential therapy

A trio of research papers from Stanford Medicine researchers and their international collaborators transforms scientists' understanding of how small DNA circles—until recently dismissed as inconsequential—are major drivers of many types of human cancers.

The papers, published simultaneously in Nature on Nov. 6, detail the prevalence and prognostic impact of the circles, called ecDNA for extrachromosomal DNA, in nearly 15,000 human cancers; highlight a novel mode of inheritance that overthrows a fundamental law of genetics; and describe an anti-cancer therapy targeting the circles that is already in clinical trials.

The team, jointly known as eDyNAmiC, are a group of international experts led by professor of pathology Paul Mischel, MD. In 2022, Mischel and the eDyNAmiC team were awarded a grant to learn more about the circles.

Cancer Grand Challenges, a research initiative co-founded by Cancer Research UK and the National Cancer Institute in the United States, supports a global community of interdisciplinary, world-class research teams to take on cancer's toughest challenges.

We're in the midst of a completely new understanding of a common and aggressive mechanism that drives cancer, say these scientists. 

Each paper alone is noteworthy, and taken together they represent a major inflection point in how we view cancer initiation and evolution.

Part 1

Comment by Dr. Krishna Kumari Challa on November 6, 2024 at 11:23am

Researchers suspected that hearing played a role in this behaviour, so they investigated the insect's auditory neurons. These lie at the base of the antennae in a structure called the Johnston's organ.

The antennae are magnificent multi-sensory apparatuses, chock-full of olfactory, mechanosensory and even thermal infrared sensilla, scientists recently discovered. In the current study, the team focused on a particular sensory channel called TRPVa—and the corresponding gene, trpVa—which is the mosquito analog of a channel required for hearing in fruit flies.
The team used CRISPR-Cas9 to knock out the gene that codes for TRPVa in Aedes aegypti mosquitoes. The resulting animals showed no reaction to sound. In fact, they found that sound elicited no electrical activity from neurons in the Johnston's organ. The insects were truly deaf.

And when the reearchers placed deaf males in chambers with females … nothing happened. If they can't hear the female wingbeat, they're not interested. Their hearing counterparts, on the other hand, wasted no time in getting busy: mating many times in the course of a few minutes.
Hearing is not only necessary for males to mate, it seems to be sufficient to rouse their desires. When the authors played the sound of female wingbeats to normal males, the males typically responded with abdominal thrusts. They were primed and ready for action. Deaf males barely twitched.
Females, however, were a different story. Deaf females still had some desire to mate left in them. The impact on the female is minimal, but the impact on the male is absolute.
In most organisms, mating behaviour is dependent on a combination of several sensory cues. In mosquitoes it depends on only one! A mosquito's physiology reveals just how important hearing is to these insects.

 Yijin Wang et al, Deafness due to loss of a TRPV channel eliminates mating behavior in Aedes aegypti males, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2404324121

Part 2

Comment by Dr. Krishna Kumari Challa on November 6, 2024 at 11:18am

Deaf male mosquitoes don't mate, researchers discover

Romance is a complex affair in humans. There's personality, appearance, seduction, all manner of physical and social cues. Mosquitoes are much more blunt. Mating occurs for a few seconds in midair. And all it takes to woo a male is the sound of a female's wingbeats. Imagine researchers' surprise when a single change completely killed the mosquitoes' libidos.

Now a study  reveals that this is really all there is to it. Researchers created deaf mosquitoes and found that the males had absolutely no interest in mating. You could leave them together with the females for days, and they will not mate.

The dramatic change was simple to produce. The absence of a single gene, trpVa, produced this profound effect on mosquito mating behaviour.

The results, published in the Proceedings of the National Academy of Sciences could have major implications for how we manage disease transmission by better controlling the populations of mosquito vectors, such as Aedes aegypti, that infect hundreds of millions of people every year with viruses that cause diseases.

Courtship for Aedes aegypti usually progresses like this: Females flap their wings at around 500 Hz. When males hear this, they take off, buzzing at about 800 Hz. The males also rapidly modulate this frequency when the ladies are around. Then there's a quick midair rendezvous, and the paramours go their separate ways. Males are always scouting out new potential partners, but a female that's successfully mated generally won't do so again.

Part 1

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