Latest Posts by theperpetualscholar - Page 6

Found on reddit (the thread has some more good ones)

Today on “rules of English language I didn’t realise were a thing until someone pointed it out”

States of Decay: Visiting the World's Largest Body Farm [Graphic Content]

[View on Google Maps] [View on YouTube]

In a field northwest of San Marcos, Texas, fifty human bodies lie exposed to the elements, each in a different stage of decomposition.

Some are fully mummified, their flesh dried out by the harsh Texas sun. Others have been picked over so voraciously by vultures that their bones are frayed. The most lurid are the fresh ones: week-old bodies that have ballooned to twice their normal size and crawl with thousands of maggots.

This is Freeman Ranch, part of the Forensic Anthropology Center at Texas State University—otherwise known as the world’s largest body farm. By observing bodily decay under varying conditions, researchers hope to help law enforcement better estimate time of death in criminal investigations.

[via: Vox]

A Few Helpful Videos

Step 1 and Done.

I don’t understand how some people can straight read First Aid and retain. Here are a few videos I found to be very helpful for understanding and memorizing concepts. With the plethora of YouTube videos out there, I feel like there should be a database of worthwhile ones somewhere (please tell me if there is already). Feel free to add any you’ve found particularly helpful. 

Anatomy

Brachial Plexus Speed Drawing

Brachial Plexus Explained

General Anatomy Overview Channel

Anatomy Figure Drawings - Helps visualize muscle actions

Biostats

Watch these a couple of days before your exam for a refresher. Many of his review questions are based directly off of UWorld questions.

Practice Questions

Cardio

General Cardio Overview  

JVP explained with relevant path correlations 

S3/S4 - the simplest of explanations (the accent does’t hurt) 

Antiarrhythmics - follow up with SketchyPharm 

Antiarrhythmics - Refractory Period Explained 

Embryology

This cardio video is amazing. He explains the cardio congenital defects in context of what causes each defect during development. This makes recall much easier as you’re learning the process and can work out each one even if you forget the small details. (make sure to watch both parts)

Heart Embryo Derivatives - mnemonic 

Intestine Development - Overview

GI Development - Foregut, Midgut, Hindgut Orientation

Embryonic Folding 

Pharyngeal Arch Mnemonic (die)  

Microbiology 

Algorithm/mnemonic for viruses. Pure gold.

YouTube Channels of Interest

Armando Hasudungan 

Anatomy Zone

Dr. Najeeb (my hero)

NCLEX Pharmacology Medical Suffixes

-amil = calcium channel blockers

-caine = local anesthetics

-dine = anti-ulcer agents (H2 histamine blockers)

-done = opioid analgesics

-ide = oral hypoglycemics

-lam = anti-anxiety agents

-oxacin = broad spectrum antibiotics

-micin = antibiotics

-mide = diuretics

-mycin = antibiotics

-nuim = neuromuscular blockers

-olol = beta blockers

-pam = anti-anxiety agents

-pine = calcium channel blockers

-pril = ace inhibitors

-sone = steroids

-statin =antihyperlipidemics

-vir = anti-virais

-zide = diuretics

There’s an app described as a “Shazam for plants” that lets you take a picture of any plant and then utilizes user data and Google reverse image searching to tell you what species you’re looking at. Source

Could this be the most powerful scientific tool?

Described as “the biggest biotech discovery of the century” by the scientific community, CRISPR-Cas has been all the rage in labs around the world for its exceptional ease and accuracy in editing the gene of almost any organism.

In 2012, UC Berkeley’s world-renowned RNA expert and biochemist Jennifer Doudna was part of a research team that discovered that you could use the CRISPR system as a programmable tool: scientists can precisely target a gene sequence, cutting and changing the DNA at that exact point. 

CRISPR, which stands for “clustered regularly interspaced short palindromic repeats” are repeated DNA sequences that are an essential component of a bacteria’s defense system against viruses.

And what started out as a study to understand the bacterial immune system unwittingly resulted in a powerful technology that has the potential to cure genetic diseases, create more sustainable crops, and even render animal organs fit for human transplants.

We’ve had gene-editing technology for decades, but now, “we’re basically able to have a molecular scalpel for genomes,” says Doudna.

“All the technologies in the past were sort of like sledgehammers.”

GIF source: Business Insider

Harvard University offers a completely free online course on the Fundamentals of Neuroscience that you can get a certificate for successfully completing and which requires nothing other than basic knowledge in Biology and Chemistry. This excites me! Here’s the website

Continuing from last week’s bread-making post, here’s a look at what’s behind the smell of fresh-baked bread! http://wp.me/p4aPLT-1Fe

Happy ‪#‎NationalWineDay‬! Here’s some red wine chemistry: http://wp.me/p4aPLT-hz

Today marks the birthday of Alfred Nier (1911-1994), a pioneer in the field of mass spectrometry. Here’s a brief mass spectrometry introduction! PDF here: http://wp.me/p4aPLT-1bw

How To Read A Stab Wound

Most emergency departments do not see much penetrating trauma. But it is helpful to be able to learn as much as possible from the appearance of these piercing injuries when you do see them. This post will describe the basics of reading stab wounds.

Important: This information will allow some basic interpretation of wounds. It will not qualify you as a forensics expert by any means. I do not recommend that you document any of this information in the medical record unless you have specific forensic training. You should only write things like “a wound was noted in the midepigastrium that is 2 cm in length.” Your note can and will be used in a court of law, and if you are wrong there can be significant consequences for the plaintiff or the defendant. This information is for your edification only.

1. What is the length of the wound? This does not necessarily correspond to the width of the blade. Skin stretches as it is cut, so the wound will usually retract to a length that is shorter than the full width of the blade.

2. Is the item sharp on one side or both? This can usually be determined by the appearance of the wound. A linear wound with two sharp ends is generally a two sided knife. A wound with one flat end and one sharp end is usually from a one-sided weapon. The picture below shows a knife wound with one sharp side.

3. Is there a hilt mark? This can usually be detected by looking for bruising around the wound. The picture below shows a knife wound with a hilt mark.

4. What is the angle? If both edges are symmetric, the knife went straight in. If one surface has a tangential appearance, then the knife was angled toward that side. You can approximate the direction of entry by looking at the tangential surface of the wound edge. In this example, the blade is angling upward toward the right.

5. How deep did it go? You have no way of knowing unless you have the blood stained blade in your possession. And yes, it is possible for the wound to go deeper than the length of the knife, since the abdominal wall or other soft tissues can be pushed inwards during the stab.

How does chemistry help make fingerprints at crime scenes visible? Here are four key methods! More info/high-res image: http://wp.me/p4aPLT-1Xb

Last year’s Halloween special looked at the chemistry of blood: http://wp.me/s4aPLT-blood

Nursing a New Year’s Day hangover? Here’s the chemistry behind it: http://wp.me/s4aPLT-hangover

Ever wondered about the chemistry behind the colours of bodily fluids? Well, urine luck! Larger image and more info: http://wp.me/p4aPLT-2j2

It’s #InternationalWomensDay! Here are twelve pioneering female chemists. Larger image & downloadable poster: http://wp.me/p4aPLT-2ra

How can isotopes help in the hunt for life, both on Earth, and on other planets? The first of our five ‪#‎RealTimeChem‬ week competition winners, Dr. Chelsea Sutcliffe, explains here: http://wp.me/p4aPLT-1tZ

New Evidence in Mice That Cocaine Makes Brain Cells Cannibalize Themselves

Working with mice, researchers at Johns Hopkins have contributed significant new evidence to support the idea that high doses of cocaine kill brain cells by triggering overactive autophagy, a process in which cells literally digest their own insides. Their results, moreover, bring with them a possible antidote, an experimental compound dubbed CGP3466B.

A summary of the study, which also found signs of autophagy in the brain cells of mice whose mothers received cocaine while pregnant, was published online the week of Jan. 18 in the Proceedings of the National Academy of Sciences.

(Image caption: A neural cell from a mouse brain shows much larger, more numerous vacuoles (orange) after 3 hours of treatment with cocaine than untreated cells. Credit: Prasun Guha, Maged Harraz, Solomon Snyder)

(Image caption: An untreated neural cell from a mouse brain shows no vacuoles. Credit: Prasun Guha, Maged Harraz, Solomon Snyder)

“We performed ‘autopsies’ to find out how cells die from high doses of cocaine,” says Solomon Snyder, M.D., professor of neuroscience at the Johns Hopkins University School of Medicine. “That information gave us immediate insight into how we might use a known compound to interfere with that process and prevent the damage.”

After discovering in 1990 that brain cells use the gas nitric oxide to communicate, Snyder and his research team have spent decades studying its impact. In 2013, the team found that nitric oxide is involved in cocaine-induced cell death through its interactions with GAPDH, an enzyme, but didn’t learn how precisely the cells were dying.

To find out, the research team examined nerve cells from mouse brains for clues. Snyder says cells, like whole animals, can die from extreme temperatures, toxins and physical trauma, but can also commit “suicide” in three ways that are chemically programmed and controlled by different proteins.

One such way is autophagy, a normal and much-needed cellular “cleanup process” that rids cells of debris that accumulates in membrane-enclosed vacuoles, or “bags” within the cell. These bags fuse with other bags, enzyme-rich lysosomes, which are filled with acids that degrade the contents of the vacuoles. Only when this process accelerates and spins out of control does it cause cell death, Snyder explains.

By measuring changes in the levels of proteins that control each cell death program and by observing the cells’ physical changes, the team saw clearly that cocaine causes neuronal cell death through out-of-control autophagy. That confirmed previous results from two other groups that found cocaine-induced autophagy in astrocytes and microglia, which are neuron support cells.

“A cell is like a household that is constantly generating trash,” says Prasun Guha, Ph.D., postdoctoral fellow at Johns Hopkins and lead author of the paper. “Autophagy is the housekeeper that takes out the trash — it’s usually a good thing. But cocaine makes the housekeeper throw away really important things, like mitochondria, which produce energy for the cell.”

Because the team already knew that nitric oxide and GAPDH were involved in the process, they tested the ability of the compound CGP3466B, known to disrupt nitric oxide/GAPDH interactions, to halt cocaine-induced autophagy. They also tested other chemicals known to prevent the other two forms of cellular suicide, but only CGP3466B protected mouse nerve cells in the brain from death by cocaine.

According to previous research from the same team, CGP3466B was also able to rescue the brain cells of live mice from the deadly effects of cocaine, but they had not connected the phenomenon to autophagy. When the scientists recently gave mice a single dose of cocaine and looked for signs of autophagy in their brain cells, they detected autophagy-associated proteins and changes in vacuoles in adults and in mouse pups whose mothers had received cocaine while pregnant.

“Since cocaine works exclusively to modulate autophagy versus other cell death programs, there’s a better chance that we can develop new targeted therapeutics to suppress its toxicity,” says Maged M. Harraz, Ph.D., a research associate at Johns Hopkins and lead co-author of the paper.

Snyder says the team hopes its work will eventually lead to treatments that protect adults and infants from the devastating effects of cocaine on the brain. Since CGP3466B has already been tested in phase II clinical trials to (unsuccessfully) treat Parkinson’s disease and ALS, it is known to be safe for humans, but the researchers caution that many more years of studies are needed to definitively show whether it is effective for preventing cocaine damage, first in mice, then in humans. They also want to create and test derivatives of CGP3466B to learn more about cocaine-induced autophagy and see if cocaine is killing any cells outside the brain.

What is the evolutionary benefit or purpose of having periods? Why can’t women just get pregnant without the menstrual cycle?

Suzanne Sadedin, Ph.D. in evolutionary biology from Monash University

I’m so glad you asked. Seriously. The answer to this question is one of the most illuminating and disturbing stories in human evolutionary biology, and almost nobody knows about it. And so, O my friends, gather close, and hear the extraordinary tale of:

HOW THE WOMAN GOT HER PERIOD

Contrary to popular belief, most mammals do not menstruate. In fact, it’s a feature exclusive to the higher primates and certain bats*. What’s more, modern women menstruate vastly more than any other animal. And it’s bloody stupid (sorry). A shameful waste of nutrients, disabling, and a dead giveaway to any nearby predators. To understand why we do it, you must first understand that you have been lied to, throughout your life, about the most intimate relationship you will ever experience: the mother-fetus bond.

Isn’t pregnancy beautiful? Look at any book about it. There’s the future mother, one hand resting gently on her belly. Her eyes misty with love and wonder. You sense she will do anything to nurture and protect this baby. And when you flip open the book, you read about more about this glorious symbiosis, the absolute altruism of female physiology designing a perfect environment for the growth of her child.

If you’ve actually been pregnant, you might know that the real story has some wrinkles. Those moments of sheer unadulterated altruism exist, but they’re interspersed with weeks or months of overwhelming nausea, exhaustion, crippling backache, incontinence, blood pressure issues and anxiety that you’ll be among the 15% of women who experience life-threatening complications.

From the perspective of most mammals, this is just crazy. Most mammals sail through pregnancy quite cheerfully, dodging predators and catching prey, even if they’re delivering litters of 12. So what makes us so special? The answer lies in our bizarre placenta. In most mammals, the placenta, which is part of the fetus, just interfaces with the surface of the mother’s blood vessels, allowing nutrients to cross to the little darling. Marsupials don’t even let their fetuses get to the blood: they merely secrete a sort of milk through the uterine wall. Only a few mammalian groups, including primates and mice, have evolved what is known as a “hemochorial” placenta, and ours is possibly the nastiest of all.

Inside the uterus we have a thick layer of endometrial tissue, which contains only tiny blood vessels. The endometrium seals off our main blood supply from the newly implanted embryo. The growing placenta literally burrows through this layer, rips into arterial walls and re-wires them to channel blood straight to the hungry embryo. It delves deep into the surrounding tissues, razes them and pumps the arteries full of hormones so they expand into the space created. It paralyzes these arteries so the mother cannot even constrict them.

What this means is that the growing fetus now has direct, unrestricted access to its mother’s blood supply. It can manufacture hormones and use them to manipulate her. It can, for instance, increase her blood sugar, dilate her arteries, and inflate her blood pressure to provide itself with more nutrients. And it does. Some fetal cells find their way through the placenta and into the mother’s bloodstream. They will grow in her blood and organs, and even in her brain, for the rest of her life, making her a genetic chimera**.

This might seem rather disrespectful. In fact, it’s sibling rivalry at its evolutionary best. You see, mother and fetus have quite distinct evolutionary interests. The mother ‘wants’ to dedicate approximately equal resources to all her surviving children, including possible future children, and none to those who will die. The fetus ‘wants’ to survive, and take as much as it can get. (The quotes are to indicate that this isn’t about what they consciously want, but about what evolution tends to optimize.)

There’s also a third player here – the father, whose interests align still less with the mother’s because her other offspring may not be his. Through a process called genomic imprinting, certain fetal genes inherited from the father can activate in the placenta. These genes ruthlessly promote the welfare of the offspring at the mother’s expense.

How did we come to acquire this ravenous hemochorial placenta which gives our fetuses and their fathers such unusual power? Whilst we can see some trend toward increasingly invasive placentae within primates, the full answer is lost in the mists of time. Uteri do not fossilize well.

The consequences, however, are clear. Normal mammalian pregnancy is a well-ordered affair because the mother is a despot. Her offspring live or die at her will; she controls their nutrient supply, and she can expel or reabsorb them any time. Human pregnancy, on the other hand, is run by committee – and not just any committee, but one whose members often have very different, competing interests and share only partial information. It’s a tug-of-war that not infrequently deteriorates to a tussle and, occasionally, to outright warfare. Many potentially lethal disorders, such as ectopic pregnancy, gestational diabetes, and pre-eclampsia can be traced to mis-steps in this intimate game.

What does all this have to do with menstruation? We’re getting there.

From a female perspective, pregnancy is always a huge investment. Even more so if her species has a hemochorial placenta. Once that placenta is in place, she not only loses full control of her own hormones, she also risks hemorrhage when it comes out. So it makes sense that females want to screen embryos very, very carefully. Going through pregnancy with a weak, inviable or even sub-par fetus isn’t worth it.

That’s where the endometrium comes in. You’ve probably read about how the endometrium is this snuggly, welcoming environment just waiting to enfold the delicate young embryo in its nurturing embrace. In fact, it’s quite the reverse. Researchers, bless their curious little hearts, have tried to implant embryos all over the bodies of mice. The single most difficult place for them to grow was – the endometrium.

Far from offering a nurturing embrace, the endometrium is a lethal testing-ground which only the toughest embryos survive. The longer the female can delay that placenta reaching her bloodstream, the longer she has to decide if she wants to dispose of this embryo without significant cost. The embryo, in contrast, wants to implant its placenta as quickly as possible, both to obtain access to its mother’s rich blood, and to increase her stake in its survival. For this reason, the endometrium got thicker and tougher – and the fetal placenta got correspondingly more aggressive.

But this development posed a further problem: what to do when the embryo died or was stuck half-alive in the uterus? The blood supply to the endometrial surface must be restricted, or the embryo would simply attach the placenta there. But restricting the blood supply makes the tissue weakly responsive to hormonal signals from the mother – and potentially more responsive to signals from nearby embryos, who naturally would like to persuade the endometrium to be more friendly. In addition, this makes it vulnerable to infection, especially when it already contains dead and dying tissues.

The solution, for higher primates, was to slough off the whole superficial endometrium – dying embryos and all – after every ovulation that didn’t result in a healthy pregnancy. It’s not exactly brilliant, but it works, and most importantly, it’s easily achieved by making some alterations to a chemical pathway normally used by the fetus during pregnancy. In other words, it’s just the kind of effect natural selection is renowned for: odd, hackish solutions that work to solve proximate problems. It’s not quite as bad as it seems, because in nature, women would experience periods quite rarely – probably no more than a few tens of times in their lives between lactational amenorrhea and pregnancies***.

We don’t really know how our hyper-aggressive placenta is linked to the other traits that combine to make humanity unique. But these traits did emerge together somehow, and that means in some sense the ancients were perhaps right. When we metaphorically ‘ate the fruit of knowledge’ – when we began our journey toward science and technology that would separate us from innocent animals and also lead to our peculiar sense of sexual morality – perhaps that was the same time the unique suffering of menstruation, pregnancy and childbirth was inflicted on women. All thanks to the evolution of the hemochorial placenta.

https://www.quora.com/what-is-the-evolutionary-benefit-or-purpose-of-having-periods

Egyptological PSA

Please learn the difference between:

Hieroglyphs (Noun): “The text is written using hieroglyphs”

Hieroglyphics (Adjective): “This is a hieroglyphic text”

The Egyptological community thanks you for your time and cooperation.

Did Megalodons Brush Their Teeth In The Morning? 

Almost everyone has heard about the Megaladon aka Carcharodon Megalodon - the terryfying, hair-raising sea creature that used to reign the waters about 10 million years ago. It’s a really huge scary shark basically.

And it is no secret that the species never suffered from tooth decay or plaques. Mostly this has been thought to be due to the regular changing of teeth. However, recently scientists have discovered that the sharks actually used toothpaste!

Well, not exactly. As it turns out, Megaladons had an interesting teeth mineral composition. Their teeth were packed were with fluoride, which is what we use in toothpaste nowadays. Fluoride made their teeth extremely strong and resistant to bacteria. And it wasn’t only Megaladons - most of the predator dinosaurs and several other species of sharks had a similar tooth meniralisation.

However, nowadays predators and other mammals do not boast a full set of shiny, fluoride-filled teeth. Humans themselves walk around with agonising pain in their teeth meanwhile the dentists are rolling in money. Why would evolution do such a thing? Having fluoride in your teeth seems like an awesome advantage, right?

Scientists aren’t really sure why the presence of fluoride was eliminated during the hostile course of evolution. The best guess is that the concentration of fluoride in water has decreased over the years and it wasn’t enough to support the teeth-changing cycles or organisms.

It may also be due to the fact that fluoride can be harmful. If fluoride encounters sour fruits or meat that isn’t fresh, hydrofluoric acid is formed. The acid is very corrosive, it can even dissolve glass. Who would want to have this in their mouths?

Source: http://www.paleonews.ru/index.php/new/588-fluoridtooth

This GIF shows how the toucan releases heat using its beak to cool itself off.

The toucan beak isn’t just beautiful, it’s also an adjustable thermal radiator that the bird uses to warm and cool itself. When the bird is hot, the blood vessels in their beak open up to allow more circulation to enable heat to escape. Birds can’t sweat so evolution has come up with some life hacks to get the job done. [video]

The eyestalk tentacles of snails are “muscular hydrostats” - the same type of structure as human tongues and elephant trunks.

Mimosa pudica is an herb of the pea family and is known for its compound leaves that fold inward and droop when touched or shaken. This defense mechanism protects the leaf from harm and allows for reopening a few minutes later. 

Chain Reaction.

Everyone knows that a line of standing dominos creates a fun chain reaction when you knock the first one over; but did you know you can use increasingly larger dominos and get the same result? 

The setup.

Professor Stephen Morris knocks over a 1-meter tall domino that weighs over 100 pounds by starting with a 5mm high by 1mm thick domino.He uses a size ratio of 1.5, meaning each domino is one and a half times larger than the last one. This is the generally accepted maximum ratio that dominos can have to successfully knock each other over.

Hans Van Leeuwen of Leiden University in the Netherlands, published a paper online showing that, theoretically, you could have a size ratio of up to two. But that’s in an ideal (and probably unrealistic) situation.

Fun fact.

There are 13 dominoes in this sequence. If Professor Morris used 29 dominoes in total, with the next one always being 1.5x larger, the last domino would be the height of the Empire State Building.

Source: Physics Buzz.