快猫短视频

YOU wouldn鈥檛 want to bathe a baby鈥檚 bottom in acid, but gentler ways to keep
delicate skin mildly acidic could actually help prevent diaper rash.

It has been known for decades that the surface of our skin is acidic, but no
one understood how it gets that way. Now Peter Elias and his team at the
Veterans Affairs Medical Center in San Francisco think they鈥檝e found out. What鈥檚
more, they say, this acidity is vital to preserve the bonds that hold our skin
together.

鈥淭his is absolutely key to understanding skin, how disease affects it and
therapeutic strategies,鈥� says Steven Hoath, a paediatrician and skin specialist
at the University of Cincinnati in Ohio. As well as making tots more
comfortable, Elias鈥檚 study could lead to novel treatments for skin disorders
such as warts and calluses, and even improved ways of delivering drugs through
the skin.

The skin鈥檚 acidity hovers around pH 5. Possible explanations for
such a low pH have included the generation of acid by friendly bacteria
or secretions from glands. These theories have assumed that because the skin鈥檚
outer layers are dead they play no active part in the process.

In fact, says Elias, the skin鈥檚 surface does more than this. 鈥淏iochemically,
it is anything but dead,鈥� he says. Though cells no longer divide, they still
contain active enzymes, which break large fat molecules called phospholipids
into smaller fatty acids. These compounds form part of a greasy glue that helps
hold cells together.

Elias and his team decided to test how much this fatty acid formation
contributes to the overall acidity of the skin. When they treated skin patches
on mice with a chemical inhibitor that stops fatty acids being formed in this
way, the skin鈥檚 pH rose by 0.5 units鈥攁 clear decrease in
acidity.

The physiological effect was even more striking: the treated skin started
losing water four times as fast as normal, and cells detached themselves from
the surface nearly five times as fast. One reason for this fragility became
obvious when they looked at the treated skin under a microscope. Half the
desmosomes鈥攑rotein 鈥渞ivets鈥� that hold skin cells together鈥攈ad broken
down.

Hoath points out that diaper rash is known to be associated with a rise in
pH caused by urine-soaked nappies. Yet treatments for the condition do
little to control pH. Elias鈥檚 work suggests that adjusting pH
with fatty acids could protect delicate skin from such damage. 鈥淚t makes sense
that anything that touches the skin should be designed to maintain its normal
physiology,鈥� says Hoath.

But there are also times when disrupting the skin could have its uses, Elias
suggests. Creams that inhibit fatty acid production could provide a gentle way
to remove warts and calluses. Or they could make skin more permeable to drugs,
he says: 鈥淲e could use these chemicals to open the door and keep it open.鈥�