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Comment by Dr. Krishna Kumari Challa on Saturday

The research team then moved a step closer to humans and transplanted the organoids into a macaque monkey whose pituitary gland had been removed. To prevent rejection of the tissue because it came from a different species, they used immune-suppressing drugs already used in transplants of human insulin-producing cells for diabetes.

The transplanted tissue worked for six weeks and successfully elevated ACTH and cortisol levels in the blood. Additionally, significant weight loss caused by the hormone deficiency slowed during this period. Three months later, tissue samples still showed surviving transplanted cells, despite strong immune rejection common in cross-species transplants, which limited how well the transplant worked.

Stem cell treatments have a known risk of cells moving from the transplant site and growing uncontrollably elsewhere in the body. The researchers checked the lungs and liver for signs of stray organoid tissue and found none.

Functional analysis of adrenocorticotropic-hormone-producing pituitary cells derived from human pluripotent stem cells in murine and primate models of hypopituitarism, Stem Cell Research & Therapy (2026). DOI: 10.1186/s13287-026-05098-y

Part 2

Comment by Dr. Krishna Kumari Challa on Saturday

First successful primate transplant of human pituitary tissue boosts cortisol levels

Researchers in Japan have transplanted pituitary tissue grown from human stem cells into a primate whose pituitary gland had been surgically removed, successfully restoring critical hormone signals. Led by researchers from Nagoya University in Japan, the team showed that the same method worked in mice over a longer period.
This is the first time lab-grown human pituitary cells have been shown to work and survive after transplantation into a primate. The study, published in the journal Stem Cell Research & Therapy, may offer a new pathway for treating lifelong hormone disorders.

The pituitary gland controls hormones for stress, growth and metabolism. When it is damaged or removed, patients rely on daily hormone pills that do not accurately mimic the body's natural fluctuations. This study tested whether lab-grown pituitary tissue can be transplanted to produce hormones naturally instead.

The pituitary gland sits at the base of the brain and releases hormones into the bloodstream. One of them is ACTH, adrenocorticotropic hormone, which signals the adrenal glands to release cortisol. Cortisol helps the body manage stress, blood pressure and blood sugar. When the pituitary fails, patients lose this signal, leading to a condition called hypopituitarism.

Without enough ACTH, the body struggles to respond to stress, which can become dangerous. Daily hormone pills for life are the standard treatment, but these pills cannot fully match the changing needs of the body because demand for cortisol shifts with stress and time of day. As a result, patients face a higher risk of sudden death.
To find a better option, the researchers turned to stem cells. They grew small lab-made masses of tissue that can act as miniature organs, called organoids, from human stem cells. The organoids contained cells that produce ACTH. The team first tested the tissue in mice whose pituitary glands were removed.

The organoids were transplanted just under the skin, in fat or muscle tissue. They produced ACTH for more than six months and clearly extended the lifespans of these mice compared to those that did not receive the transplant. No unwanted tumours or unusual cell growth were observed.
Part 1

Comment by Dr. Krishna Kumari Challa on Saturday

Too little salt may hurt memory just as badly as too much

Salt can make or break a dish. A little too much or too little can throw everything off, leaving even the most luxurious ingredients tasting off. But get the balance right, and salt can bring out the flavour in even the simplest ingredients. The brain relies on a similar balancing act for healthy function and memory. While we are aware of the ill effects of having too much salt, what happens when we consume too little?
A recent study compared how long-term low-salt and high-salt diets affected memory, gut health and brain health in mice whose guts were colonized with human gut bacteria. The researchers focused on the gut–metabolite–brain axis, examining how dietary salt alters gut bacteria and their chemical products, and how those changes signal back to the brain.

Mice on either a low-salt or a high-salt diet struggled with memory. Compared with mice eating a normal amount of salt, they did worse on tests of short-term working memory and long-term recognition memory.

Inside the hippocampus, the brain's memory center, both diets lowered critical synaptic proteins like SYN1, PSD95 and BDNF and suppressed CREB activation. All of these are essential tools neurons use to build memories and adapt, so weakening them reduced the brain's ability to form memories.
Tests by researchers indicated that both eating too little salt and eating too much salt impair memory and brain function, but through two different biological pathways. With a low-salt diet, a drop in essential hippocampal synaptic proteins impaired long-term and short-term memory.

A high-salt diet significantly increased pro-inflammatory signals circulating in the blood and shifted the gut microbiota toward a pro-inflammatory state by lowering faecal levels of propionate and butyrate. This led to increased oxidative stress markers in the intestine, which can often trigger higher anxiety-like behaviour.
The results demonstrate the importance of a balanced, normal salt intake for one's overall brain and gut health. Too little salt starves the brain of vital gut-derived chemical signals, while too much salt causes inflammatory damage.

Anji Chen et al, Long-term low-salt and high-salt diets differentially disrupt the gut–metabolite–brain axis and induce cognitive impairment, Food Research International (2026). DOI: 10.1016/j.foodres.2026.119719

Comment by Dr. Krishna Kumari Challa on Friday

Gut bacterial compound worsens brain injury after stroke, study suggests

How much damage a stroke causes in the brain depends strongly on how quickly blood flow can be restored. The patient's own immune response that follows the stroke also plays an important role.

Researchers have discovered how a metabolite produced by gut bacteria can influence brain damage after stroke. Their paper is published in the journal Cell.

They have now identified a specific bacterial signal that shapes this immune response and influences stroke outcome.
Gut bacterial indole worsened brain injury after stroke in mice through AHR signaling in dendritic cells. Disabling AHR in these cells promoted protective immune responses and reduced injury. In patients with ischemic stroke, higher bacterial TnaA abundance was associated with poorer functional outcomes.

The researchers found that in mice with severe stroke, gut bacteria capable of producing indole, a metabolite that is only produced in the gut, become more abundant. These bacteria carry the gene tnaA, which allows them to convert the amino acid tryptophan, found in food, into indole. In mice, the team showed that indole-producing bacteria worsened brain injury after stroke.

Indole acts on a receptor called AHR (aryl hydrocarbon receptor), found in dendritic cells—immune cells that patrol the intestinal lining and help coordinate immune responses. When the researchers switched off AHR specifically in dendritic cells, mice were better protected against brain injury.

Dendritic cells have long extensions, like arms, that allow them to sense changes in their environment, including metabolites produced by gut bacteria. When scientists switched off AHR, the behaviour of these cells changed completely: Dendritic cells were better able to migrate from the intestine to the meninges, the membranes surrounding the brain. These dendritic cells also promoted protective T cells and helped reduce the damage in the brain.
The researchers also found evidence that this pathway may be relevant in humans. In a cohort of human patients with ischemic stroke, the ISD team found that a higher abundance of bacterial TnaA was associated with poorer functional outcomes.
The findings raise an important question for future research: Could changing the gut microbiome or the metabolites it produces in healthy individuals help prepare the immune system to respond differently if a stroke occurs?

Rosa Delgado Jiménez et al, Gut microbiota primes stroke severity via the AHR in intestinal dendritic cells, Cell (2026). DOI: 10.1016/j.cell.2026.09.013

Comment by Dr. Krishna Kumari Challa on Friday

The biological clock regulates phases of wakefulness

The circadian clock is an internal biological system that regulates sleep-wake cycles, as well as many physiological functions such as body temperature and hormone production. In many animals, this clock relies on a network of neurons that generates rhythms of approximately 24 hours.
These neurons must then transmit this information to other regions of the brain, allowing activity and behaviour to be adapted to the time of day.
A circuit linking the biological clock to wakefulness
Imaging techniques that measure neuronal activity allowed researchers to show that this activity varies throughout the day. They identified a connection between the biological clock neurons and a population of neurons that produce dopamine, a molecule that enables neurons to communicate with one another.
Researchers observed that the clock neurons inhibit these dopaminergic neurons, which in turn stimulate neurons in the mushroom body. This brain region plays a role in learning, memory and the regulation of sleep, and its activity contributes to promoting wakefulness during the day
When the clock neurons inhibit the dopaminergic neurons, the wake-promoting signal decreases. Conversely, when this inhibition is released, the dopaminergic neurons can more strongly stimulate the mushroom body and promote wakefulness. Through its neurons, the biological clock can therefore transmit information about the time of day to a brain circuit involved in regulating sleep and wakefulness.

These findings shed light on how the biological clock influences sleep and wake states. In particular, they highlight the central role of dopamine in promoting wakefulness and show how information from the biological clock is relayed through different neural circuits throughout the day.

Disruptions of the circadian clock are associated with various sleep disorders and alterations in brain function. A better understanding of these fundamental mechanisms could ultimately help explain how disturbances in biological rhythms affect the brain.

Blanca Lago Solis et al, Circadian control of dopaminergic signaling to the mushroom body regulates sleep through rhythmic Pka-C1 transcription in Drosophila, Current Biology (2026). DOI: 10.1016/j.cub.2026.09.014

Comment by Dr. Krishna Kumari Challa on October 1, 2026 at 11:50am

Skipping sweets during antibiotic treatment may help protect the gut microbiome

A new study by researchers suggests eating less sugar could protect the microbiome during antibiotic treatment. The study followed patients with blood cancer undergoing an intensive treatment called allogeneic hematopoietic cell transplant, a population at particularly high risk for severe gut microbiome disruption and associated side effects.

In stem cell transplant patients taking broad-spectrum antibiotics, each additional 100 g of sweets was associated with 24% lower gut bacterial diversity. High-sucrose diets promoted Enterococcus overgrowth in antibiotic-treated mice.
Published in Nature, the findings connect to the idea of "food as medicine" during cancer care and the ways diet can help us prevent and recover from illness. The research could lead to new treatment strategies for cancer patients and potentially others taking antibiotics.

Antibiotics disrupt the diversity of our gut bacteria, or microbiomes, which play an essential role in supporting our immune systems and overall health.
This new research supports emerging evidence that avoiding sugary foods during antibiotic treatment may protect the microbiome. Preserving microbiome diversity has previously been linked with improved clinical outcomes for patients with cancer.
Antibiotics are used to treat infections, but they also broadly destroy good bacteria in the gut, allowing harmful microbes to overgrow.

The five-year study, one of the largest of its kind, followed patients who were hospitalized for several weeks to receive intensive chemotherapy, sometimes with radiation, to wipe out their immune systems before undergoing a stem cell transplant.

To prevent and treat infections, each patient took at least one antibiotic during their hospital stay. Some 80% took one or more broad-spectrum antibiotics, which have the strongest effect on the microbiome because they target many types of bacteria.

The research team tracked 9,419 meals eaten by 173 hospitalized patients and profiled microbiome diversity in stool samples from 158 patients. Microbiome diversity is a key indicator of a healthy microbiome.

Using a variety of advanced statistical models, the researchers searched the data for patterns linked to injury to the gut microbiome.

What they found surprised them.
The patients who consumed more sweets while taking antibiotics were more likely to experience a loss of microbiome diversity as aggressive microbes crowded out other strains of bacteria.

One organism stood out: Enterococcus. When it takes over the microbiome, patients undergoing transplant face a higher risk of bloodstream infections, graft-versus-host disease and other life-threatening complications.

The combination of high-sugar foods and broad-spectrum antibiotics appeared to multiply injury to the microbiome, leading to a 24% drop in bacterial diversity for every 100-gram (3.5-ounce) increase in sweets (equivalent in sugar content to a large milkshake).
The researchers also tested their hypothesis that sugar exacerbates microbiome injury by giving broad-spectrum antibiotics to healthy mice and feeding them a variety of diets. Mice that ate a high-sucrose diet quickly developed an overgrowth of Enterococcus in their guts. Mice that ate the high-sugar diet without antibiotics, however, maintained normal bacterial diversity.

Jonathan Peled, Sugar-rich foods exacerbate antibiotic-induced microbiome disruption, Nature (2026). DOI: 10.1038/s41586-026-11077-3. www.nature.com/articles/s41586-026-11077-3

Comment by Dr. Krishna Kumari Challa on September 30, 2026 at 1:14pm

Research shows poor mental health among politicians may impair decision-making

Longitudinal data from UK and international MPs link psychological distress with lower confidence in political decision-making and differences in how MPs assess choices and risks. The findings support better mental health support for representatives and safeguards for major decisions, but do not establish causation.

James Weinberg et al, The inner cabinet: how mental health impacts political decision-making, Parliamentary Affairs (2026). DOI: 10.1093/pa/gsag038

Comment by Dr. Krishna Kumari Challa on September 30, 2026 at 12:55pm

We don't actually know how many species there are on Earth. Estimates range from 8 million to 20 million. Scientists have identified only 1.5 million to 1.7 million, with around 16,000 new ones added to the list every year.

Some animals are tiny, live in hard-to-reach places or closely resemble known species.
Roughly half of known beetle species are so rare that they have been identified from a single specimen—the only one ever found. Identify it, and it's probably the last time you'll see it.
Given how quickly species are going extinct, the search has become a race against time.

"The assumption is we're losing ones we don't know about yet".
Why is it important to formally identify new species?

New discoveries, such as the recent revelation of Leopardus tilcayo, as "a wonderful reminder of how much remains unknown."
We cannot protect or fully appreciate what we have not yet recognized or understood.
Moreover, a population may look healthy only because scientists have lumped it together with its relatives.

"That's the real importance of recognizing a species from a subspecies".

Jonas Lescroart et al, Phylogenomics and museomics reveal five distinct species of tiger cats in South America, Current Biology (2026). DOI: 10.1016/j.cub.2026.08.059

Part 2

Comment by Dr. Krishna Kumari Challa on September 30, 2026 at 12:51pm

How do scientists determine what counts as a separate species?
Sometimes one glance is all it takes.

You see a zebra and a giraffe, and they look completely different.
But this method doesn't always work with cats.

They say all cats look the same in the dark, and the tilcayo and its close cousins are no different. Even in broad daylight, they all resemble "a bunch of little leopard-spotted cats". Felines as a whole share a surprising number of physical traits.
Once nature reaches perfection, it only tweaks a little.
When animals look alike, scientists need a different way to determine where variation within one species ends and another begins. One way is by looking at reproduction. Can the animals breed, and can their descendants do the same?

In recent decades, scientists have increasingly turned to genetic analysis when asking whether a population forms its own recognizable branch on the evolutionary tree.

Even within the same species, DNA varies a bit. As populations adapt to different environments, however, traits that give them an advantage take root. They make the genetic differences between groups more pronounced over time.

Scientists compare these differences and use statistical methods to decide when a genetic signature becomes a sign of a separate species.

How are new species discovered?
Decades ago, scientists collected specimens in the field and compared them to known animals.
While expeditions still happen, DNA technology has given scientists a new way to spot differences that aren't visible to the eye.

That said, there's a difference between a species being scientifically identified and a species being known.
For example, local communities were aware of the tilcayo for generations.

It's also important to remember that nature doesn't pause to file paperwork when one species becomes two. Instead, it's an ongoing process. Scientists use the concept of subspecies to mark groups in transition.
New species also form when animals from different groups interbreed, producing descendants that follow a separate evolutionary path.

That's exactly what's going on in the case of tiger cats.
in southern Brazil, two of five existing species—Geoffroy's cats and Atlantic Forest cats—are interbreeding as they adapt to human-altered landscapes. This is allowing scientists to watch a sixth species emerge in real time.

"We're seeing evolution in action" .

Part 1

Comment by Dr. Krishna Kumari Challa on September 30, 2026 at 12:10pm

Now, Shyamsundar is investigating how nanoparticles can be used to improve cancer treatments. Traditional chemotherapy attacks cancerous and healthy cells, often causing severe side effects. By designing nanoparticles that can better exploit the acidic tumour microenvironment for drug release, she hopes to improve the delivery of chemotherapy drugs to cancer cells while reducing damage to healthy tissue.

To do this, she uses the nanoparticle core as an anchor for molecules—known as a ligand shell—that can regulate what is released and when. The shell resembles a pom-pom, with strings that can both protect the drug and treat cancer depending on the environment they enter. By changing the chemistry of these anchored molecules, she can more precisely tune drug release.
She also investigated factors affecting the formation of lipid nanoparticles for vaccine delivery. She wants to combine her expertise from academia and industry to develop a broader understanding of nanoparticle drug delivery systems.
For her efforts, Shyamsundar earned the Lois Jean Durham Scholarship, which recognizes excellence in chemistry and biochemistry.

The shell hides the drug when the nanoparticle is in the chemical environment of healthy cells, but when it reaches the acidic environment near cancer cells, the particles spring into action.

Changing ligand shell behaviour has the potential to make a big impact on how the drug releases.

I am impressed!

Kaveen Tennakoon et al, Isolating Ligand Steric Effects on Metal Ion Reduction and Gold Nanoparticle Formation Pathways Using Au(I)–Phosphine Complexes, Langmuir (2026). DOI: 10.1021/acs.langmuir.6c02684

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