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Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 1:05pm

Rising pollen levels linked to increased mortality in older adults

As climate change intensifies pollen seasons across some regions, new research  reveals a connection between pollen exposure and death rates among older adults with breathing problems.

The study, published in BMC Public Health, shows that high pollen days aren't just an inconvenience for allergy sufferers—they could pose serious health risks for vulnerable populations. With pollen seasons growing longer and more intense, understanding these risks has become increasingly urgent for public health officials and health care providers.

The study found that high levels of certain pollen, particularly from deciduous trees and ragweed, were linked to increased risk of death from breathing problems. The effects could last up to two weeks after exposure.

The findings suggest that exposure to certain types of pollen can increase the risk of death from breathing-related problems, particularly for people with chronic conditions. This is especially concerning given expectations that climate change will exacerbate the severity of pollen seasons in coming years.

The researchers looked at four types of pollen: deciduous tree pollen from trees that lose their leaves, evergreen tree pollen, grass pollen and ragweed pollen.

While not everyone is equally sensitive to pollen, the findings highlight the importance of tracking pollen levels and taking precautions during high pollen days, especially for older adults with breathing problems, the researchers say. And, they add, with predicted climate change, preparing for the risks will be increasingly important for public health.

 Peter S. Larson et al, Chronic and infectious respiratory mortality and short-term exposures to four types of pollen taxa in older adults in Michigan, 2006-2017, BMC Public Health (2025). DOI: 10.1186/s12889-025-21386-3

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 1:01pm

Method to measure blood-brain barrier permeability accurately developed

For decades, scientists across the globe have investigated methods to accurately measure drug permeability across the blood-brain barrier, a compact layer of cells that protect the brain from potentially dangerous substances and microbes. They struggled with a number of parameters, such as blood flow and binding to plasma proteins, which were shown to impact permeability in different ways.

In research published in the December 2024 issue of Fluids and Barriers of the CNS ("Brain endothelial permeability, transport and flow assessed over 10 orders of magnitude using the in situ brain perfusion technique"), researchers  sought to reconcile discrepancies in the field and provide accurate methods for measuring permeability over a very broad range spanning from poorly crossing polar compounds (compounds with a positive or negative charge) to rapidly crossing approved central nervous system (CNS) clinical drugs.

The project team evaluated 120 compounds, revealing that many current CNS drugs permeate the barrier and equilibrate in the brain in less than 10 minutes. The findings challenged previous literature and demonstrated that the equilibration rate for a significant number of CNS drugs is much greater than previously realized.

The researchers showed that many of the drugs that are used and approved for CNS uptake go into the brain quite well. A good number of agents in the benzodiazepine, antidepressant, antipsychotic, stimulant and antiepileptic drugs go in as quickly as the blood flow can deliver them. It's amazingly rapid. For such agents, we had to have extremely accurate measurement of cerebral blood flow.

The project also highlighted the role of plasma proteins which, for many lipophilic agents can serve an additional brain delivery role beyond that of free drug in plasma. In effect, plasma-bound drugs can dissociate to maintain the intervascular free drug concentration, which otherwise would show rapid depletion under conditions of higher extraction (50–99%). 

 Quentin R. Smith et al, Brain endothelial permeability, transport, and flow assessed over 10 orders of magnitude using the in situ brain perfusion technique, Fluids and Barriers of the CNS (2024). DOI: 10.1186/s12987-024-00584-y

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:55pm

Climate change may be delaying births, suggests study

New  research has found exposure to outdoor air pollution and extreme temperatures during pregnancy may increase the risk of prolonged pregnancy, offering new insights into the impact of climate change on maternal health.

Published in Urban Climate, the study is titled "Maternal climate-related exposures and prolonged pregnancy: Findings from a statewide population-based cohort study in Western Australia."

The study analyzed data from nearly 400,000 births in Western Australia and found that higher exposure to fine particulate air pollution (PM_2.5) and biothermal stress (a measure that combines air temperature, radiant temperature, relative humidity, wind speed, and human physiology) was associated with pregnancies lasting beyond 41 weeks.

While climate exposure has long been linked to preterm births, this is the first study to examine its impact on prolonged pregnancies.

These  findings show that exposure to air pollution and biothermal stress during pregnancy increases the likelihood of prolonged pregnancies, particularly among mothers over 35 years old, first-time mothers, those living in urban areas, and those with complicated pregnancies.

"Environmental stressors, including climate-related exposures during pregnancy, have been associated with maternal stress response and subsequent disruptions in endocrine and inflammatory activities, which increase towards the end of pregnancy. This can either shorten gestation, leading to preterm birth, or lengthen gestation, resulting in prolonged pregnancy in some cases."

 Prolonged pregnancy can have serious health implications for both mother and baby, including the need for medical interventions such as labor induction or cesarean sections, increased risk of stillbirth, birth complications, child mortality, early childhood behavioral and emotional problems, and emotional impacts on families.

This study highlights the need for targeted policies and preventative measures to reduce climate-related health risks, including better air quality regulations and public health initiatives aimed at protecting expectant mothers and children from extreme climatic conditions.

Sylvester Dodzi Nyadanu et al, Maternal climate-related exposures and prolonged pregnancy: Findings from a statewide population-based cohort study in Western Australia, Urban Climate (2025). DOI: 10.1016/j.uclim.2025.102316

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:37pm

The secret behind sharp vision: New research reveals the benefits of tiny eye movements

Even when we think we are holding our gaze perfectly still, our eyes make tiny, involuntary movements. While these "fixational eye movements" might seem like they would blur our vision, new research reveals they actually help us see fine details more clearly.

In a study combining theoretical modeling and human experiments,  researchers and their collaborators  have uncovered how these microscopic eye movements enhance rather than impair our visual acuity.

Using advanced eye-tracking technology and computational models, the team demonstrated that these movements help our retinas process visual information more effectively. Their paper is published in the Proceedings of the National Academy of Sciences.

It is a fascinating paradox, say the researchers. These constant, tiny movements of our eyes might appear to make our vision less precise, but they actually optimize the way our retinas encode visual information. We found that humans naturally maintain these movements within a nearly perfect range for enhanced visual acuity.

The researchers found that these movements help by 'refreshing' the content of our visual receptors while maintaining an optimal balance between motion and stability. They also found that in the experiment, the movements adapt to the size of the object shown.

The study was conducted using a sophisticated adaptive optics scanning laser ophthalmoscope, allowing researchers to track these minute eye movements with unprecedented precision while participants performed visual tasks. The researchers then combined theoretical modeling with empirical data to link eye movements to retinal neural coding and human behaviour.

Trang-Anh E. Nghiem et al, Fixational eye movements as active sensation for high visual acuity, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2416266122

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:22pm

Unlike female sexual traits, the loss of male sexual traits is generally thought to take an extremely long time. In many other species, even rare males often retain their reproductive capabilities. However, these findings suggest that R. mikado has relied solely on parthenogenesis for such an extended period that even neutral mutations have accumulated, leading to the complete loss of male reproductive traits.
This study demonstrates that parthenogenesis in R. mikado has become irreversible. Although asexual reproduction is often considered evolutionarily short-lived due to the lack of genetic recombination, previous research estimated that this species has persisted for hundreds of thousands of years. How has R. mikado managed to survive for such a long time? This remains an intriguing mystery for future research.

Tomonari Nozaki et al, Lack of successful sexual reproduction suggests the irreversible parthenogenesis in a stick insect, Ecology (2025). DOI: 10.1002/ecy.4522

Part 2

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 12:21pm

Study shows male stick insects have lost their reproductive function

While most animals reproduce sexually, some species rely solely on females for parthenogenetic reproduction. Even in these species, rare males occasionally appear. Whether these males retain reproductive functions is a key question in understanding the evolution of reproductive strategies.

A new study published in Ecology by a research team provides insight into this question. The researchers focused on the rare males of Ramulus mikado, a stick insect species in Japan, where parthenogenesis is predominant. Their analysis of male reproductive behavior reveals new findings.

Males engage in mating but do not contribute genetically. The rare males actively mated with females, just like typical males. However, genetic analysis confirmed that no male-derived genes were passed on to their offspring. The study further revealed that these males do not produce functional sperm, rendering them incapable of restoring sexual reproduction in the species.

Their findings showed that the males exhibited the typical morphological traits of stick insects and engaged in mating behaviors with conspecific females. However, despite their reproductive attempts, they were completely sterile. At the same time, the female reproductive organs associated with sexual reproduction showed signs of degeneration.

The rare males of this stick insect have completely lost their reproductive function.

Part 1

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:36am

Why babies recover, but adults scar, after heart damage

Newborns with heart complications can rely on their newly developed immune systems to regenerate cardiac tissues, but adults aren't so lucky. After a heart attack, most adults struggle to regenerate healthy heart tissue, leading to scar-tissue buildup and, often, heart failure.

A new  study in experimental animals reveals a critical difference in how macrophages—a part of the immune system—help repair the heart in newborns versus adults after a heart attack. The study highlights a fundamental difference in how the immune system drives healing based on age.

The study is published in the journal Immunity.

In newborns, macrophages perform a process called efferocytosis, which recognizes and eats dying cells. This process triggers the production of a bioactive lipid called thromboxane, signaling nearby heart muscle cells to divide, and allowing the heart to regenerate damaged heart muscle, the study found. In adults, macrophages produce much less thromboxane, leading to a weaker repair signal.

"By mimicking the effects of thromboxane, we might one day improve tissue repair after a heart attack in adults," the researchers say.

Early Age Efferocytosis Directs Macrophage Arachidonic Acid Metabolism for Tissue Regeneration, Immunity (2025).

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:21am

As expected, the engineered bacteria localized specifically in the olfactory epithelium and released their payloads into adjacent brain regions. Mice fed a high-fat diet and treated with hormone-secreting bacteria exhibited reduced body weight gain, lower food consumption, improved glucose tolerance and diminished adipose tissue deposition compared with control groups.

Findings further indicated that leptin secreted by the bacteria persisted in the olfactory epithelium longer than recombinant leptin delivered intranasally.

Results support the method's potential as a noninvasive vector for brain-targeted therapies. While the study used an appetite-regulating hormone, this delivery system could be adapted for neurological conditions such as Parkinson's disease, Alzheimer's, and brain cancers, where drug penetration into the brain remains a major hurdle.

Haosheng Shen et al, Engineered commensals for targeted nose-to-brain drug delivery, Cell (2025). DOI: 10.1016/j.cell.2025.01.017

Part 2

Comment by Dr. Krishna Kumari Challa on February 12, 2025 at 8:20am

Crossing the blood–brain barrier with a payload via engineered bacteria

Researchers  have reported crossing the blood–brain barrier with help from a modified Lactobacillus plantarum. By delivering an appetite-regulating hormone directly to the olfactory epithelium, the hormone was able to reach its target.

Only the secreted hormone molecules crossed into the brain. Engineered Lactobacillus plantarum remained in the nasal passage, where it released its therapeutic payload, which then diffused along the olfactory pathway into the brain.

Current approaches to treating neurological conditions suffer from the highly protective nature of the blood–brain barrier. Intranasal therapies often encounter rapid clearance without a sustained therapeutic delivery.

In the study "Engineered Commensals for Targeted Nose-to-Brain Drug Delivery," published in Cell, researchers address these challenges by exploiting L. plantarum's natural affinity for the olfactory epithelium.
L. plantarum was chosen as a delivery vector as it naturally localizes to the olfactory epithelium binding sites. Initial investigations involved engineering L. plantarum to express and secrete hormones such as leptin, alpha-melanocyte-stimulating hormone and brain-derived neurotrophic factor (BDNF).

Experiments incorporated in vitro models using nasal cell monolayers and in vivo studies with male mice aged 6 to 8 weeks. Intranasal administration of fluorescent-labeled bacteria allowed visualization of bacterial localization.

Part 1

Comment by Dr. Krishna Kumari Challa on February 11, 2025 at 12:03pm

Mitochondria's role in diabetes

Mitochondria are essential for generating energy that fuels cells and helps them function.

Mitochondrial defects, however, are associated with the development of diseases such as type 2 diabetes. Patients who suffer from this disorder are unable to produce enough insulin or use the insulin produced by their pancreas to keep their blood sugar at normal levels.

Several studies have shown that insulin-producing pancreatic β-cells of patients with diabetes have abnormal mitochondria and are unable to generate energy. Yet, these studies were unable to explain why the cells behaved this way.

In a study published in Science, researchers used mice to show that dysfunctional mitochondria trigger a response that affects the maturation and function of β-cells.

The researchers also confirmed their findings in human pancreatic islet cells.

Mitochondrial dysfunction affects several types of cells

Their results prompted the team to expand their search into other cells that are affected during diabetes.

Reversing mitochondrial damage could help cure diabetes

Regardless of the cell type, the researchers found that damage to the mitochondria did not cause cell death.

This observation brought up the possibility that if they could reverse the damage, the cells would function normally.

To do so, they used a drug called ISRIB that blocked the stress response. They found that after four weeks, the β-cells regained their ability to control glucose levels in mice.

Losing your β-cells is the most direct path to getting type 2 diabetes. Through this study we now have an explanation for what might be happening and how we can intervene and fix the root cause.

Emily M. Walker et al, Retrograde mitochondrial signaling governs the identity and maturity of metabolic tissues, Science (2025). DOI: 10.1126/science.adf2034

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