Neuroscience and biochemistry enthusiast
Joined October 2025
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Brenda retweeted
A nerve guidance conduit (also known as an artificial nerve conduit or artificial nerve graft) is an artificial device that guides axonal regrowth to facilitate nerve regeneration and is one of several clinical treatments for nerve injuries.
#MedTwitter #MedX @IhabFathiSulima
A severed nerve doesn't have to mean permanent loss of function.
This patient accidentally cut their median nerve. To fix it, we performed a cable graft—essentially building a bridge for the nerve fibers to grow across and reconnect.
This is the reconstruction side of #PlasticSurgery restoring form AND function ⚡️🔌
#MedTwitter #Surgery #HandSurgery #Reconstruction #Nerve
Brenda retweeted
Psychiatric disorders are not explained by genetic vulnerability alone.
Stress, trauma, substance use, nutrition, infection, and medication can also shape gene expression.
That is where epigenetics becomes clinically relevant. 🧵👇
Brenda retweeted
🚨 The ovarian cyst was opened—and inside were hair and a tooth!
A 24-year-old woman presents with intermittent pelvic pain and abdominal fullness. Ultrasound reveals a complex right ovarian mass containing cystic and echogenic components. During surgery, the excised lesion reveals greasy yellow material, a tuft of hair, and a tooth-like structure.
❓ What is the most likely diagnosis, and which acute complication should be suspected if she develops sudden severe pelvic pain with vomiting?
🤖 Made with AI
Another question related to longevity
Does your metabolism (fast or slow) relate to how fast you would age?
Most exercise and aging studies can't answer a basic question: is muscle deterioration from aging itself, or just from decades of moving less? A new Nature Aging study solved this by recruiting older adults who moved as much as people in their twenties.
The researchers from Amsterdam UMC and Maastricht University recruited four distinct groups: young adults in their twenties, older adults whose daily step counts and high-intensity activity matched the young group, older adults who had trained consistently for years (three structured hour-long sessions per week for over a year), and older adults with early physical impairment.
They took muscle biopsies before and after a one-hour cycling session, then measured over 24,000 gene transcripts, 135 metabolites, and 1,383 lipid species.
By matching activity levels between young and older groups, any molecular differences couldn't be blamed on the older adults simply moving less. This isolated aging from inactivity for the first time at this molecular depth.
Key findings:
• The defining molecular signature of muscle aging is an energy crisis. Comparing young adults to activity-matched older adults, 1,106 genes were downregulated with age. These genes build the mitochondrial machinery that produces cellular energy: ATP synthase, cytochrome c oxidase, and NADH dehydrogenase subunits. Mitochondria are the power plants of cells, converting nutrients into ATP, the energy currency cells use to function. When these genes decline, cells lose their ability to generate energy efficiently.
• NAD+ levels declined and triglycerides accumulated inside aging muscle. NAD+ is a molecule required for energy production and cellular repair. Lower NAD+ means less capacity to convert fuel into usable energy. Triglycerides are stored fats, their accumulation inside muscle indicates unburned fuel piling up as the tissue loses its ability to process it.
• More than half the molecular signature of muscle aging was absent in trained older adults. Specifically, 57.1% of age-related gene downregulation and 55.9% of upregulation were missing in the trained group. Their muscle resembled young adults far more than their chronological age would predict.
• The changes training preserved were specifically the energy metabolism ones. Genes like NDUFS1 and COX5A, which were depleted in normally active and impaired older adults, sat at youthful levels in the trained group across all five mitochondrial respiratory complexes. The single most prominent feature of muscle aging turned out to be the single most preventable.
• Being generally active was not enough. Structured training was the difference. The normally active older adults walked as much as young adults, and their energy metabolism genes declined anyway. What preserved the youthful molecular profile was structured, sustained training. Filling a step counter and being genuinely trained are not equivalent at the molecular level.
• Roughly half of muscle aging persisted regardless of training. Changes in genes controlling synaptic transmission (how nerves communicate with muscle) and WNT signaling (a pathway regulating tissue maintenance and stem cell function) appeared in all older adults, trained or not. This unavoidable half is where drugs will have to work.
• The fittest muscle mounted the largest inflammatory response to exercise. All groups activated stress and immune genes after exercise, including IL6, IL1B, and TNF. But the magnitude scaled with fitness. Trained older adults most closely resembled young adults in their response, followed by normally active, with impaired older adults showing the most blunted response. The stress response to exercise appears to be the mechanism of adaptation, not damage to be minimized.
This raises a concern about anti-inflammatory longevity strategies. If the inflammatory stress response is how exercise produces its benefits, chronically suppressing inflammation may blunt the adaptation that exercise depends on. It doesn't mean inflammation is beneficial in general, but the timing and context matter.
A separate discovery: the proteasome appears to regulate NAD+. The proteasome is the cellular machinery that breaks down damaged proteins. When researchers inhibited it, NAD+ levels rose in both muscle and liver cells to a degree comparable to NAD+ precursor supplements. This opens a new route to understanding NAD+ decline that operates through protein turnover rather than just supplying more raw material.
The study draws a clear line between what lifestyle can address and what will require therapeutics. The energy metabolism decline, mitochondrial deterioration, and NAD+ depletion that define muscle aging are largely preventable through structured training. The synaptic and signaling changes that persist in all older adults represent the unavoidable half where drugs will need to work.
The decisions made about structured training in midlife determine which molecular trajectory muscle follows in later decades. Half of muscle aging is optional. The other half isn't. Knowing which changes belong to each category is knowing where behavior ends and biology takes over.
How do you explain many smart people with ugly face
Las personas con mayor cociente intelectual tienden a tener mayor atractivo físico, mayores habilidades deportivas, mayor fuerza muscular y mayor felicidad.
Estas asociaciones pueden deberse al apareamiento asortativo cruzado: por ejemplo, los hombres más inteligentes, hábiles y fuertes tienden a alcanzar mayor estatus socioeconómico y, a su vez, tienden a preferir emparejarse con mujeres más atractivas físicamente. Al tratarse de rasgos altamente heredables, esta combinación se transmite a la siguiente generación, generando una correlación positiva entre estos rasgos en los hijos.
También puede explicarse por factores de fitness general o estabilidad del desarrollo: estos rasgos reflejarían la calidad genética subyacente y la estabilidad del desarrollo embrionario y postnatal (el llamado f-factor). Esta mayor calidad biológica influiría positivamente en varios rasgos a la vez.
A su vez, a nivel ambiental, los rasgos también podrían influirse unos a otros: por ejemplo, una mayor inteligencia favorece un mayor autocontrol y una mayor sabiduría, lo que ayuda a tomar mejores decisiones en los hábitos de vida, como entrenar o seguir una dieta más saludable, lo que favorecería, entre otros efectos, una mayor fuerza y una mayor felicidad. Sin embargo, muchas de estas correlaciones se observan ya en la infancia, lo que indica que en gran parte se deben a factores innatos.
Brenda retweeted
A large analysis of children's brain scans reveals that socioeconomic status is the primary factor shaping brain organization. The findings suggest that brain patterns previously linked to intelligence actually reflect environmental factors like stress… dlvr.it/TVYLP5
Brenda retweeted
Neanderthals were stronger, faster, with bigger brains, and more robust. Yet, Homo sapiens outcompeted them.
Neanderthal larger bodies and brain required more neural resources for vision and physical control.
Homo sapiens had more allocation to other functions, specifically social cognition and social intelligence.
One study estimated that this allowed Homo sapiens to maintain social networks of ~139 people compared to the ~115 for Neanderthals.
That might have given humans an advantage in cooperation, sharing ideas, maintaining larger networks for acquiring/exchanging resources, finding mates, etc.
Neanderthals had many advantages as individuals, but humans had the advantage as a collective.
Graph: PMID: 23486442
Brenda retweeted
The question of gay/straight twins is common, so if anyone was wondering:
These questions show a clear lack of knowledge and twin studies prove biological origin.
Attraction to males appears to be the developmental default for the human brain in many models of prenatal development. Without sufficient exposure to androgens like testosterone during key windows, the brain tends toward androphilia (attraction to males). Male heterosexuality, in this view, often involves active masculinisation by prenatal hormones interacting with genes. Brown skin works as a good analogy here: it is the typical human outcome, not that every baby is born exactly the same shade or that only brown skin is natural.
Your idea that we are wired exclusively heterosexual unless something goes awry does not hold up well. A male who is attracted to males is simply following one common variation of that default trajectory rather than the fully androgen-influenced path. Heterosexuality is the most common outcome, but it is not the only natural one.
Heterosexuality is not strictly required for the species to survive, either. Homosexuality does not equal infertility, and most gay and lesbian people have heterosexual relatives who reproduce. The biological requirement is simply that sperm and egg meet somewhere in the population. Recreational or pair-bonding sex is separate from that reproductive necessity.
Your point about identical twins also needs updating. Twin studies actually support the biological view. Concordance for homosexuality is higher in identical twins (around 30–65% across studies) than in fraternal twins (around 20–30%), yet it is never 100%. This shows both genetic influences and non-shared factors at work, especially differences in prenatal hormone exposure even in the same womb. Identical twins do not always share identical uterine environments, placental blood flow, or hormone timing, so their neural circuitry can develop differently. These studies point to innate, biologically driven origins which doesn’t align with your view, so it doesn’t make sense to pretend that they do.
The current scientific consensus is that sexual orientation arises from a mix of genetic factors, prenatal hormones, and other aspects of the early prenatal developmental environment. Life experiences do not change the core orientation itself, though they can affect how openly or comfortably someone expresses it.
Fields like neurology, genetics, endocrinology, and developmental biology find no solid evidence that non-biological choice or social factors create the orientation. It is a natural part of human variation, much like left-handedness.
You are trying to create equivalence where there is none. The norm is man/woman attraction - without which the species ends. It is both the default and of clear value to the species. It's the way we are wired, unless something goes awry - natural or otherwise.
I think you over-state the polygenic influence, while ignoring environmental factors. Scientists believe sexual orientation is the result of a complex interplay of genetics, hormonal environments in the womb, and life experiences. If it was simple genetics and womb environment, why do identical twins not always have the same sexuality? It suggests non-biological factors do play a role.
It seems that I finally remember it. It's about making a dead person come back to life using a chemical.
Brenda retweeted
I’m a Chinese college student. I hope to make real foreign friends.Especially English, I use English and Chinee
I’m troubled by bots and improper links to adult all the time
Feel free to message me if you’d like to chat about culture, food, politics or military. Let’s be friends
does lesion in ferrets hypothalamus changes its amygdala structure? Hypothalamus is hardly what triggers sexual orientation. There's only male typical and female typical hypothalamus. But bisexual orientation exists. human sexual orientation is diverse.
Brenda retweeted
“머리가 멍한 진짜 이유… ‘목’에 있습니다”
15년차 한의사입니다. 머리가 멍하고 안개가 낀 듯한 느낌, 의학적으로는 ‘브레인 포그’ 상태라고 합니다.
그런데 이 현상은 목 근육이 경직되어 있을수록, 그리고 거북목처럼 목의 정렬이 틀어져 있을수록 더 심해질 수 있다는 사실, 알고 계셨나요?
목에서 뇌로 가는 혈류가 원활하지 않으면 이러한 증상이 더욱 악화될 수 있습니다.
그리고 더 중요한 점이 있습니다.
뇌에는 ‘글림파틱 시스템’이라는 일종의 야간 청소 시스템이 있어, 뇌 속 노폐물인 베타 아밀로이드를 제거하는 역할을 합니다. 그런데 목 근육이 경직되어 뇌로 가는 혈류가 감소하면, 이 시스템이 제대로 작동하기 어려워질 수 있습니다. 즉, 뇌 속 노폐물이 충분히 배출되지 못하고 쌓일 가능성이 높아진다는 의미입니다.
따라서 거북목은 단순한 자세 문제가 아니라, 장기적인 뇌 건강 관리 측면에서도 중요하게 볼 필요가 있습니다.
스스로 케어할 수 있는 방법을 안내드리겠습니다.
턱을 목 쪽으로 살짝 당겨 ‘이중턱’을 만들어 주십시오.
그 상태에서 정수리 위로 끈이 연결되어 있다고 상상하시고, 위로 길게 당겨 올린다는 느낌을 가져보십시오.
이때 뒷목이 길어지는 느낌이 드는 것이 중요합니다.
He did a plastic surgery.
Brenda retweeted
This is Algebrica. A mathematical knowledge base I’ve been building for 2.5 years.
215+ entries, carefully written and structured.
400k+ views over this time. Not much in absolute terms, but meaningful to me.
No ads.
No courses to sell.
No gamification.
No distractions.
Just essential pages, aiming to explain mathematics as clearly as possible, for a university-level audience.
Built simply for the pleasure of sharing knowledge.
Content licensed under Creative Commons (BY-NC).
Best experienced on desktop.
If it helps even a few people understand something better, it’s worth it.
Brenda retweeted
China cracks down on pretty boys in media
Recently Chinese costume drama Pursuit of Jade 逐玉 gained high ratings and viewership. This attracted the attention of censors.
National Radio and Television Administration called a meeting w various TV stations, criticizing TV trends focusing on looks, demands stop idol/looks worshipping, establishing healthy aesthetic etc.
IMO the issue is disconnect between people who watch TV Dramas and people who criticize TV Dramas. TV Drama audience is primarily women. TV shows usually cater to their viewers' tastes. People who criticize the prevalence of pretty boys in TV shows are usually men but they don't watch those TV dramas anyway.
Of course the boomers in the censorship department always err in the direction of maximum control.
Brenda retweeted
Your smartphone may be performing 2.6 million calculations per second while you scroll, but your brain can only hold 7 pieces of information in working memory at once.
That mathematical mismatch explains why every creative professional you know complains about having “no time to think” despite consuming more information than any generation in human history.
Dr. Sophie Leroy at the University of Washington discovered something she calls “attention residue.” When you switch from consuming content to creating something, fragments of what you just consumed continue processing in the background of your mind. Her team showed this happening. The prefrontal cortex lights up with activity that has nothing to do with the creative task at hand.
You think you’re writing an original email after checking Twitter, but your brain is still running calculations on twelve different conversations you scrolled past. You think you’re solving a design problem after watching YouTube, but part of your mental processing power is still trying to complete thoughts that belonged to strangers.
The implications of this research demolish the entire way we think about inspiration and creative input.
Every writer, designer, and entrepreneur believes they need to “stay informed” to stay creative. They follow industry blogs, consume case studies, track competitor moves, and absorb thought leadership content because they’ve been told that creativity comes from combining existing ideas in new ways.
The attention residue findings suggest the opposite is true. The more frequently you interrupt your mental workspace with external input, the less processing power you have available for original combinations.
Your brain doesn’t combine ideas. It gets trapped trying to finish processing ideas that were never yours to begin with.
Real creativity happens in the cognitive space between problems, when your mind has nothing to react to and starts making connections that don’t exist in any external source. But that space has to be protected like a crime scene. One notification, one article, one podcast episode can contaminate it for hours.
Watch what happens to your thinking patterns when you eliminate information input completely for 72 hours. Most people can’t do it. The withdrawal is physical. Your brain has learned to outsource its entertainment to external feeds, and when those feeds disappear, the silence feels unbearable.
But around hour 48, something remarkable occurs. Your internal monologue stops being commentary on things you’ve read and becomes a conversation with ideas that have no clear source. You start building mental models instead of consuming them. You start asking questions that don’t have obvious answers instead of seeking answers to questions other people already asked.
I read somewhere that Maya Angelou kept a hotel room with nothing in it but a bed and a notepad because she discovered her best writing happened when her mind had nowhere to go but inward. Tesla could design entire machines in his head and run them mentally for weeks to test for flaws because his cognitive workspace wasn’t cluttered with input from other inventors.
Consumption and creation compete less for time and more for same neural pathways.
Every piece of content you absorb trains your brain to expect external stimulation instead of generating internal signal.
Your best work isn’t waiting for better information.
It’s waiting for less information to get in its way.
Brenda retweeted
我向父母正式地出櫃為男同志，是在出版自己的BL漫畫《老師，男友還給我》的前幾週。不過在那之前，不善藏隱匿的我從小就露出不少馬腳。
小時候在客廳用電腦，逛猛男網站沒有發現後方有媽媽經過。或是大掃除的時候，把喜歡的人的名字寫在窗戶上畫一顆愛心框住。還有在分享IG短片的時候，忘記刪掉網址後綴，導致基弟台Gaydio的帳號被發現。
一直一來，都是「我知道你知道，你也知道我知道你知道」的狀態。告訴父母我有男朋友還有漫畫的事情後，很幸運地得到家人們的接納，也稱讚我的漫畫畫得很好，他們都有看到。（不過由於一直以來露出馬腳，反而造成了溫水煮青蛙的效果，讓我在正式出櫃時沒有帶給家人太大的衝擊...）
