Category: Health & Medicine

The Dark Side of Laughter

laughter

(Credit: durantelallera/Shutterstock)

When you hear someone laugh behind you, you probably picture them on the phone or with a friend – smiling and experiencing a warm, fuzzy feeling inside. Chances are just the sound of the laughter could make you smile or even laugh along. But imagine that the person laughing is just walking around alone in the street, or sitting behind you at a funeral. Suddenly, it doesn’t seem so inviting.

The truth is that laughter isn’t always positive or healthy. According to science, it can be classified into different types, ranging from genuine and spontaneous to simulated (fake), stimulated (for example by tickling), induced (by drugs) or even pathological. But the actual neural basis of laughter is still not very well known – and what we do know about it largely comes from pathological clinical cases. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

Malaria During Pregnancy Could Bolster Babies’ Immunity

By Kim Smuga-Otto | June 5, 2017 3:27 pm
tanzanian-mother

A mother and baby from the village of Pomerini, Tanzania. It’s estimated that the disease kills 60,000 to 80,000 people there annually. (Credit: Franco Valpato/Shutterstock)

You have a bit of your mother in you, literally.

When scientists performed biopsies of young adults’ organs, they’ve found maternal cells embedded in hearts, kidneys, and liver. This phenomenon, called microchimerism, is caused by a small number of cells passing through the placenta during pregnancy. The transfer goes both ways, and scientists think it’s like a meet-and-greet between mom and fetus, preventing their immune systems from treating each other’s cells as dangerous invaders. But that doesn’t explain why these cells stick around long after birth. Read More

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How the Chemicals in Sunscreen Protect Our Skin

Don’t skimp on the SPF. Sabphoto via Shutterstock.com

Don’t skimp on the SPF. (Credit: Sabphoto/Shutterstock)

Kerry Hanson, University of California, Riverside

Not so long ago, people like my Aunt Muriel thought of sunburn as a necessary evil on the way to a “good base tan.” She used to slather on the baby oil while using a large reflector to bake away. Aunt Muriel’s mantra when the inevitable burn and peel appeared: Beauty has its price. The Conversation

Was she ever right about that price – but it was a lot higher than any of us at the time recognized. What sun addicts didn’t know then was that we were setting our skin up for damage to its structural proteins and DNA. Hello, wrinkles, liver spots and cancers. No matter where your complexion falls on the Fitzpatrick Skin Type scale, ultraviolet radiation (UV) from the sun or tanning beds will damage your skin.

Today, recognition of the risks posed by UV rays has motivated scientists, myself included, to study what’s going on in our cells when they’re in the sun – and devise modern ways to ward off that damage.

UV light that affects our skin has a shorter wavelength than the parts of the electromagnetic spectrum we can see. Inductiveload, NASA, CC BY-SA

UV light that affects our skin has a shorter wavelength than the parts of the electromagnetic spectrum we can see.
(Credit: Inductiveload/NASA/CC BY-SA)

What Happens When Sun Hits Skin

Sunlight is composed of packets of energy called photons. The visible colors we can see by eye are relatively harmless to our skin; it’s the sun’s ultraviolet (UV) light photons that can cause skin damage. UV light can be broken down into two categories: UVA (in the wavelength range 320-400 nanometers) and UVB (in the wavelength range 280–320 nm).

(Credit: The Conversation, CC-BY-ND)

(Credit: The Conversation, CC-BY-ND)

Our skin contains molecules that are perfectly structured to absorb the energy of UVA and UVB photons. This puts the molecule into an energetically excited state. And as the saying goes, what goes up must come down. In order to release their acquired energy, these molecules undergo chemical reactions – and in the skin that means there are biological consequences.

Interestingly, some of these effects used to be considered helpful adaptations – though we now recognize them as forms of damage. Tanning is due to the production of extra melanin pigment induced by UVA rays. Exposure to the sun also turns on the skin’s natural antioxidant network, which deactivates highly destructive reactive oxygen species (ROS) and free radicals; if left unchecked, these can cause cellular damage and oxidative stress within the skin.

We also know that UVA light penetrates deeper into the skin than UVB, destroying a structural protein called collagen. As collagen degrades, our skin loses its elasticity and smoothness, leading to wrinkles. UVA is responsible for many of the visible signs of aging, while UVB light is considered the primary source of sunburn. Think “A” for aging and “B” for burning.

DNA itself can absorb both UVA and UVB rays, causing mutations which, if unrepaired, can lead to non-melanoma (basal cell carcinoma, squamous cell carcinoma) or melanoma skin cancers. Other skin molecules pass absorbed UV energy on to those highly reactive ROS and free radicals. The resulting oxidative stress can overload the skin’s built-in antioxidant network and cause cellular damage. ROS can react with DNA, forming mutations, and with collagen, leading to wrinkles. They can also interrupt cell signaling pathways and gene expression.

The end result of all of these photoreactions is photodamage that accumulates over the course of a lifetime from repeated exposure. And – this cannot be emphasized enough – this applies to all skin types, from Type I (like Nicole Kidman) to Type VI (like Jennifer Hudson). Regardless of how much melanin we have in our skin, we can develop UV-induced skin cancers and we will all eventually see the signs of photo-induced aging in the mirror.

Filtering Photons Before Damage Is Done

The good news, of course, is that the risk of skin cancer and the visible signs of aging can be minimized by preventing overexposure to UV radiation. When you can’t avoid the sun altogether, today’s sunscreens have got your back (and all the rest of your skin too).

Sunscreens employ UV filters: molecules specifically designed to help reduce the amount of UV rays that reach through the skin surface. A film of these molecules forms a protective barrier either absorbing (chemical filters) or reflecting (physical blockers) UV photons before they can be absorbed by our DNA and other reactive molecules deeper in the skin.

(Credit: The Conversation, CC-BY-ND)

(Credit: The Conversation, CC-BY-ND)

In the United States, the Food and Drug Administration regulates sunscreens as drugs. Because we were historically most concerned with protecting against sunburn, 14 molecules that block sunburn-inducing UVB rays are approved for use. That we have just two UVA-blocking molecules available in the United States – avobenzone, a chemical filter; and zinc oxide, a physical blocker – is a testament to our more recent understanding that UVA causes trouble, not just tans.

The FDA also has enacted strict labeling requirements – most obviously about SPF (sun protection factor). On labels since 1971, SPF represents the relative time it takes for an individual to get sunburned by UVB radiation. For example, if it takes 10 minutes typically to burn, then, if used correctly, an SPF 30 sunscreen should provide 30 times that – 300 minutes of protection before sunburn.

“Used correctly” is the key phrase. Research shows that it takes about one ounce, or basically a shot glass-sized amount of sunscreen, to cover the exposed areas of the average adult body, and a nickel-sized amount for the face and neck (more or less, depending on your body size). The majority of people apply between a quarter to a half of the recommended amounts, placing their skin at risk for sunburn and photodamage.

In addition, sunscreen efficacy decreases in the water or with sweating. To help consumers, FDA now requires sunscreens labeled “water-resistant” or “very water-resistant” to last up to 40 minutes or 80 minutes, respectively, in the water, and the American Academy of Dermatology and other medical professional groups recommend reapplication immediately after any water sports. The general rule of thumb is to reapply about every two hours and certainly after water sports or sweating

 In the U.S., the FDA regulates sunscreens available to consumers. Sheila Fitzgerald/Shutterstock.com

In the U.S., the FDA regulates sunscreens available to consumers. (Credit: Sheila Fitzgerald/Shutterstock)

What Makes A Good Sunscreen

To get high SPF values, multiple UVB UV filters are combined into a formulation based upon safety standards set by the FDA. However, the SPF doesn’t account for UVA protection. For a sunscreen to make a claim as having UVA and UVB protection and be labeled “Broad Spectrum,” it must pass FDA’s Broad Spectrum Test, where the sunscreen is hit with a large does of UVB and UVA light before its effectiveness is tested.

This pre-irradiation step was established in FDA’s 2012 sunscreen labeling rules and acknowledges something significant about UV-filters: some can be photolabile, meaning they can degrade under UV irradiation. The most famous example may be PABA. This UVB-absorbing molecule is rarely used in sunscreens today because it forms photoproducts that elicit an allergic reaction in some people.

But the Broad Spectrum Test really came into effect only once the UVA-absorbing molecule avobenzone came onto the market. Avobenzone can interact with octinoxate, a strong and widely used UVB absorber, in a way that makes avobenzone less effective against UVA photons. The UVB filter octocrylene, on the other hand, helps stabilize avobenzone so it lasts longer in its UVA-absorbing form. Additionally, you may notice on some sunscreen labels the molecule ethylhexyl methoxycrylene. It helps stabilize avobenzone even in the presence of octinoxate, and provides us with longer-lasting protection against UVA rays.

Next up in sunscreen innovation is the broadening of their mission. Because even the highest SPF sunscreens don’t block 100 percent of UV rays, the addition of antioxidants can supply a second line of protection when the skin’s natural antioxidant defenses are overloaded. Some antioxidant ingredients my colleagues and I have worked with include tocopheral acetate (Vitamin E), sodium ascorbyl phosophate (Vitamin C), and DESM. And sunscreen researchers are beginning to investigate if the absorption of other colors of light, like infrared, by skin molecules has a role to play in photodamage.

As research continues, one thing we know for certain is that protecting our DNA from UV damage, for people of every color, is synonymous with preventing skin cancers. The Skin Cancer Foundation, American Cancer Society and the American Academy of Dermatology all stress that research shows regular use of an SPF 15 or higher sunscreen prevents sunburn and reduces the risk of non-melanoma cancers by 40 percent and melanoma by 50 percent.

We can still enjoy being in the sun. Unlike my Aunt Muriel and us kids in the 1980s, we just need to use the resources available to us, from long sleeves to shade to sunscreens, in order to protect the molecules in our skin, especially our DNA, from UV damage.

 

This article was originally published on The Conversation. Read the original article.

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: personal health

Why Quality Sleep Grows More Elusive with Age

By Mark Barna | May 1, 2017 10:12 am
insomnia

(Olga Kuevda/Shutterstock)

Middle-agers and seniors on average sleep less than younger people, about 6 to 7 hours a night compared to 8 to 9 hours.

But why is this so? And are older people therefore sleep deprived, which can give rise to chronic maladies and speed up aging? Read More

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MORE ABOUT: personal health

Novel Antibiotic Recipes Could Be Hidden in Medieval Medical Texts

By Erin Connelly, University of Pennsylvania | April 25, 2017 10:20 am
shutterstock_8875816

(Credit: Filip Fuxa/Shutterstock)

For a long time, medieval medicine has been dismissed as irrelevant. This time period is popularly referred to as the “Dark Ages,” which erroneously suggests that it was unenlightened by science or reason. However, some medievalists and scientists are now looking back to history for clues to inform the search for new antibiotics.

The evolution of antibiotic-resistant microbes means that it is always necessary to find new drugs to battle microbes that are no longer treatable with current antibiotics. But progress in finding new antibiotics is slow. The drug discovery pipeline is currently stalled. An estimated 700,000 people around the world die annually from drug-resistant infections. If the situation does not change, it is estimated that such infections will kill 10 million people per year by 2050. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: vaccines & drugs

Revisited: The Regenerative Power of Pig Guts

By Adam Piore | March 27, 2017 3:09 pm
pig-guts

(Credit: AVA Bitter/Shutterstock)

Bioengineers have made great strides harnessing the body’s ability to start over, whether regenerating heart tissue and bones, or using stem cells to regrow fingertips. Still, much of regenerative medicine’s promise remains inside the laboratory—or at least that was what I thought when I began reporting for The Body Builders: Inside the Science of the Engineered Human.

Some clinicians, like Dr. Eugenio Rodriguez, aren’t waiting for trials to be completed to help patients. Instead, they are already adding regenerative technologies to their medical toolboxes, and using them to save human limbs. Years ago down in Delray Beach, Florida, Rodriguez, a trauma surgeon, caused a bit of a sensation after exploring the regenerative powers of pig guts. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: biotechnology

Soaking in a Hot Bath Yields Benefits Similar to Exercise

By Steve Faulkner, Loughborough University | March 21, 2017 11:17 am

shutterstock_357044915

Many cultures swear by the benefits of a hot bath. But only recently has science began to understand how passive heating (as opposed to getting hot and sweaty from exercise) improves health. The Conversation

At Loughborough University we investigated the effect of a hot bath on blood sugar control (an important measure of metabolic fitness) and on energy expended (number of calories burned). We recruited 14 men to take part in the study. They were assigned to an hour-long soak in a hot bath (40˚C) or an hour of cycling. The activities were designed to cause a 1˚C rise in core body temperature over the course of one hour. Read More

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MORE ABOUT: personal health

VX Nerve Agent: The Deadly Weapon Engineered in Secret

By Carl Engelking | February 24, 2017 4:30 pm
gas-mask

A World War II-era contamination suit. (Credit: Shutterstock)

In January 1958, two medical officers at Porton Down, Britain’s military science facility, exposed their forearms to 50-microgram droplets of a substance called VX, which was a new, fast-acting nerve agent that could kill by seeping through the skin.

VX, short for “venomous agent X,” is tasteless, odorless and causes uncontrollable muscle contractions that eventually stop a person’s breathing within minutes. That experiment in 1958, according to University of Kent historian Ulf Schmidt, was perhaps the first human test of VX in the Western world. Read More

Metagenomic Sleuthing Treats Illness Like a Crime Scene

By Kim Smuga-Otto | February 16, 2017 1:09 pm

Charles Chiu in the lab with colleague Steve Miller. (Credit: Elisabeth Fall/UCSF)

Pathogens move fast.

You wake up one morning feeling ready to take on the world. On your way to work, you notice your throat’s a bit scratchy, your forehead a bit warm. By lunch you’ve got a pounding headache and it hurts to breathe. Co-workers agree, you’ve got whatever’s been going around. You end the day early, using the last of your strength to drag yourself to bed. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: genes and health

You Might Be in a Medical Experiment and Not Even Know It

By Alice Dreger | January 31, 2017 12:34 pm

shutterstock_387017350

In the long view, modern history is the story of increasing rights of control over your body – for instance, in matters of reproduction, sex, where you live and whom you marry. Medical experimentation is supposed to be following the same historical trend – increasing rights of autonomy for those whose bodies are used for research.

Indeed, the Nuremberg Code, the founding document of modern medical research ethics developed after the Second World War in response to Nazi medical experiments, stated unequivocally that the voluntary, informed consent of the human subject is essential. Every research ethics code since then has incorporated this most fundamental principle. Exceptions to this rule are supposed to be truly exceptional. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts
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