Viet Van Dang/ Mister Astrocyte

Mission: Use Magic to filter, Nonsense!🧹 It's magic!✨Electric Engineer| Astrocyte Fan| Chess| Science History Collector| Unicycle| Autodidact | Altruist
#SPD

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

“Science taps the power of human understanding to look at the world and figure out how it works. It can't fail without humanity itself failing. Your magic could turn off, and you would hate that, but you would still be you. You would still be alive to regret it.

[Dr. Gennadi Glinsky, MD, Ph.D. @gglinskii]

A Hormone Cell Atlas maps the human endocrine system at cellular resolution | Science https://t.co/s3X9l37Rs6

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

https://t.co/e4oQn2p27i
https://t.co/h7Nkewsw1w

[Niko McCarty. @NikoMcCarty]

There is a new paper in Science proposing a mechanism for how homing pigeons navigate on cloudy days. (Hint: It's magnetic fields.)

As with many magnetobiology papers, though, I'm skeptical of their proposed mechanism.

These researchers, from Germany, found that pigeons have macrophages in their liver that accumulate lots of iron. They confirmed this with staining and other analyses. These macrophages also tend to cluster near nerve fibers in the liver (this is important for later).

Then they did a really interesting experiment:
- Train 34 pigeons to fly a particular 19-kilometer route. Ensure they all do this well.
- Split the pigeons into two groups: treatment and control.
- Inject the treatment group pigeons with liposomes loaded with clodronate. The macrophages eat these liposomes, and then clodronate kills the cells and scatters the iron.
- Release the pigeons, from both groups, on an overcast day (it's thought that pigeons use magnetic fields to navigate when there is no sun).
- All of the control pigeons reached their destination within 70 minutes, but the treated pigeons scattered in random directions.
- (Important control experiment: The treated pigeons, released on a sunny day, flew like normal and reached their destination.)
- This is taken as evidence that ??? macrophages --> iron --> navigation ??? via magnetic fields. But the mechanism is fuzzy.

This experiment is super interesting, and it's clear that the treated pigeons really are unable to home to their destination using a magnetic field. But I'm not entirely convinced by the mechanism these authors propose.

The main claim is that these iron-loaded macrophages "align" in a magnetic field, and that they shift according to the bird's orientation so that it can fix its direction. These macrophages (somehow) send signals to the nerve fibers in the liver, which then pass the messages to the brain, which allows the bird to navigate.

The news coverage for this story suggests how this might happen: "One idea is that as the bird shifts its position relative to Earth’s magnetic field lines, the ferritin changes orientation and tugs on the web of fibers within a macrophage, possibly triggering the release of signaling molecules." (All you need to do is read the 2016 Meister paper, from the images below, to understand why such a mechanism is physically dubious.)

The problem, though, is that the authors show (in their own study) that the iron in these pigeons' livers only act as a stable magnet at super low temperatures, below about 12 degrees Kelvin (or -260 degrees Celsius). At normal, physiological temperatures, the iron would be scrambled by the thermal motions of the tissue. Every measurement in the paper is taken at cryogenic temperatures, but a bird's body temperature is much higher, which means heat would likely destroy any magnetic alignment.

The authors claim that MILLIONS of iron particles in the liver are all acting together to escape this effect, but they don't demonstrate the mechanism convincingly at all. If this claim is true, why not take homing pigeons (control vs. macrophage-depleted) and then rotate a magnetic field around them? You could record their neurons to see if there is some kind of signal coming from the liver.

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

@furan https://t.co/HkwhuqpaTu
This was all vibecoded.

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

@furan Hey men! You should really vibecode with the newest Claude Opus 4.8, a small game.

I attempted to run the 8bitworkshop locally on the screen via SDL on Ubuntu Linux 22.04 and i find this experience so great!

[John Lukens @LukensJohnR]

Microglial mitochondria transfer to astrocytes via GPNMB-enriched extracellular vesicles alleviates cognitive deficits in tauopathy mice
@NatureNeuro

[Orchid Advocacy @OrchidAdvocacy]

Astrocyte Sodium Levels Vary to Match Local Synaptic Needs - https://t.co/vNxE3177PB via @neurosciencenew

[Nature Metabolism @NatMetabolism]

#Throwback

REVIEW | JP Bolaños & PJ Magistretti

The neuron–astrocyte metabolic unit as a cornerstone of brain energy metabolism in health and disease

https://t.co/faUCTEeCzL

[María A. Moro @MariAngelesMoro]

The metabolic engine of cognition: microglia–neuron interactions in health, ageing and disease | Nature Metabolism https://t.co/GX98AdKWtZ

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

@Ayussheth sure

[Zdenek Vrozina @ZdenekVrozina]

Sanhueza at al., De novo COVID-19-associated insulin resistance drives dysregulated neutrophil extracellular trap formation (NETosis) four months after infection. https://t.co/0kbuOMZRAA

[Dr. Tana Sue Pottorf (Nitcher) @PottorfTana]

Excited to share our new paper in @SfNJournals exploring how microglial TREM2 influences BOTH degeneration and regeneration after peripheral nerve injury.

We found that microglia respond very differently depending on the state of the injured motoneuron.

https://t.co/3NFXFPLbRl

[Andrew Octavian Sasmita @AOSasmita]

Astrocytes reduce microglial activation and enhance adult hippocampal neurogenesis in acute inflammation

https://t.co/0L9aAX8POn

[Ryuta Koyama @ryuta_koyama]

Astrocyte glucocorticoid receptor signalling restricts neuronal plasticity

https://t.co/Pdtbrb5DgX

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

@EricTopol @ScienceTM The only Research, that prevents us from depleting our groundwaters with the current usage/Training of AI Models "by just calculating 3x5".

Glial Cell Research is the future about ourselves, our neurological diseases and our thirst for more wisdom.
Claude Shannon had Alzheimer.

[allen institute @AllenInstitute]

Neurons don't connect randomly.

In this video by our #ElectronMicroscopy team, a blue neuron's axon forms a connection to a far neuron. Along the way, it links to some neighbors while skipping thousands. Connectomics seeks to understand what makes those connections special.

[Ruth Ann Crystal, MD @CatchTheBaby]

MIT found Alzheimer's-like amyloid plaques in the brains of people who died of COVID. https://t.co/QbSJWJQhGW

Spike proteins were clustering with amyloid.

This was not in older adults with pre-existing disease.

It was caused by COVID.

[Ruslan Rust @rust_ruslan]

Cool study!

Spatial proteomic analysis in human Alzheimer’s disease brains enables identification of microenvironment-dependent microglial cell states @NatureNeuro

https://t.co/1dGUwBXFz8

[Ruslan Rust @rust_ruslan]

Pericyte Loss Reprogrammes Capillary Endothelium and Drives White Matter Injury in Small Vessel Disease. Great preprint by @MontagneLab 👏

https://t.co/vO4Kpp67U6

[Viet Van Dang/ Mister Astrocyte @BrainWizard2]

https://t.co/iqPfOXlSvt