TechTweets


hook This hook starts with a "have you ever wondered" question, but then makes it more concrete by situating it in a personal narrative. The personal narrative also tells us why the author is writing about this now. The second tweet includes a poll, which tests how much people already know about the subject.		Tony Breu @tony_breu · Jul 11 1/ "Why do my fingers get all wrinkly when I take a bath?” This was the question my 3-year-old daughter asked me recently after bath time. I thought for a minute, then realized I didn't have a clue. The explanation is so much cooler than I had expected... https://t.co/mFyeKm8Edc
	Tony Breu @tony_breu · Jul 11 2/ Let me throw a version of my daughter's question out to you: Which of the following contributes to “water immersion wrinkling"?
mechanism narrative This short narrative presents what happens when you put your hand in water from the perspective of the water. Using water as a kind of character (it drives the action) helps the author set up a conceptual contradiction resolved in the subsequent discovery narrative.		Tony Breu @tony_breu · Jul 11 3/ For 40 years, I have observed, like my daughter, that my fingers look like prunes after being in water. I’ve assumed that they lost water (became dehydrated), just like prunes! But, that can’t be. When I submerge my hand in water, I’m placing it into a hypotonic solution.
	Tony Breu @tony_breu · Jul 11 4/ Reminder: Plasma osmolality: ~285 mOsm/kg Water osmolality: ~0 mOsm/kg If anything, water should flow IN and make my fingertips MORE swollen.
	Tony Breu @tony_breu · Jul 11 5/ It's true that water enters fingers after immersion. The portals of entry are likely sweat glands (which are highly concentrated in the hands). But, fingers appear to shrink, not swell. And it’s not uniform. Something else must be going on. https://t.co/VZy5eYjbJe https://t.co/v6Pu1uACP3
discovery narrative Now the author walks us through the story of how scientists discovered why our fingertips wrinkle. To heighten the drama, we get several clues before understanding the entire process.		Tony Breu @tony_breu · Jul 11 6/ A major clue came in 1936 when Lewis and Pickering published their observation that skin innervated by a palsied median nerve failed to wrinkle. This suggested the phenomenon wasn’t simply about water flow, but that it also involved the nervous system. https://t.co/fWZ85C43VA https://t.co/JjOYHEceZY
	Tony Breu @tony_breu · Jul 11 7/ It appears that nerve activation is essential to water immersion wrinkling. But what does increase nerve firing lead to? Sympathetic mediated vasoconstriction! https://t.co/16WSpF9myW
	Tony Breu @tony_breu · Jul 11 8/ The same group that suggested vasoconstriction as a contributor to wrinkling also offered a reason for why we experience it more on the glabrous skin (i.e., smooth/hairless) of the fingertips and toes.
	Tony Breu @tony_breu · Jul 11 9/ Two keys regarding fingertip anatomy: anchoring of the epidermis to the dermis results in varying skin tautness (max where skin is anchored) distal digital pulp has a high concentration of blood vessels and lots of glomus bodies (AV shunts surrounded by connective tissue)
	Tony Breu @tony_breu · Jul 11 10/ When glomus bodies lose volume through vasoconstriction, a negative pulp pressure is generated. The result is a downward pull on the overlying skin. Because dermal anchoring is not uniform in the fingertips, there is variable pull. Result: WRINKLING!
	Tony Breu @tony_breu · Jul 11 11/ In 2004 a more complete mechanism was proposed: water enters via sweat glands ➡️ electrolyte abnormalities ➡️ decreased membrane stability ➡️ increased nerve firing ➡️ vasoconstriction, particularly within dermal pulp ➡️ pull-down of overlying skin ➡️ wrinkles
use case narrative Here the author goes through how someone might use this information in a clinical setting.		Tony Breu @tony_breu · Jul 11 12/ Is there a way we can make use of this information clinically, or is it just cocktail party fodder? Well, if a functioning peripheral nerve is required for water immersion wrinkling, maybe its presence/absence can be used to test for neuropathy…
	Tony Breu @tony_breu · Jul 11 13/ Since the 1970s, numerous groups have studies exactly this. It’s been used in diseases causing neuropathies as diverse as diabetes (PMID 6734390) and leprosy (PMID 3006371). https://t.co/wbjWBdMDv2 https://t.co/0S046esGk1 https://t.co/bH821fa6Yk
	Tony Breu @tony_breu · Jul 11 14/ Have you ever used fingertip wrinkling to evaluate nerve function?
payoff The author gives us the same poll as last time, to check if more people get the correct answer. In the final tweet, the author returns us to the situation in the hook, the three year old asking a question during bath time, and gives us a one-sentence summary that answers the question.		Tony Breu @tony_breu · Jul 11 15/ Before closing, let’s return to the original question: Which of the following contributes to “water immersion wrinkling"?
	Tony Breu @tony_breu · Jul 11 16/ Next time my daughter takes a bath, I'll explain that her fingers look like raisins because she has intact sympathetic vasoconstriction with resulting retraction of fingertip pulp and that the density of eccrine sweat glands in her hands contributes. She’s come to expect it.

hook
This hook starts with a "have you ever wondered" question, but then makes it more concrete by situating it in a personal narrative. The personal narrative also tells us why the author is writing about this now. The second tweet includes a poll, which tests how much people already know about the subject.

Tony Breu @tony_breu · Jul 11

1/ "Why do my fingers get all wrinkly when I take a bath?” This was the question my 3-year-old daughter asked me recently after bath time. I thought for a minute, then realized I didn't have a clue. The explanation is so much cooler than I had expected... https://t.co/mFyeKm8Edc

[Tweet image. If not displayed, your browser may be blocking content from Twitter. Try turning off content blocking to view images on this page; on Firefox this can be done by clicking on the shield just to the left of the URL and turning off Enhanced Tracking Protection for this site only.]

Tony Breu @tony_breu · Jul 11

2/ Let me throw a version of my daughter's question out to you: Which of the following contributes to “water immersion wrinkling"?

mechanism narrative
This short narrative presents what happens when you put your hand in water from the perspective of the water. Using water as a kind of character (it drives the action) helps the author set up a conceptual contradiction resolved in the subsequent discovery narrative.

Tony Breu @tony_breu · Jul 11

3/ For 40 years, I have observed, like my daughter, that my fingers look like prunes after being in water. I’ve assumed that they lost water (became dehydrated), just like prunes! But, that can’t be. When I submerge my hand in water, I’m placing it into a hypotonic solution.

Tony Breu @tony_breu · Jul 11

4/ Reminder: Plasma osmolality: ~285 mOsm/kg Water osmolality: ~0 mOsm/kg If anything, water should flow IN and make my fingertips MORE swollen.

Tony Breu @tony_breu · Jul 11

5/ It's true that water enters fingers after immersion. The portals of entry are likely sweat glands (which are highly concentrated in the hands). But, fingers appear to shrink, not swell. And it’s not uniform. Something else must be going on. https://t.co/VZy5eYjbJe https://t.co/v6Pu1uACP3

[Tweet image. If not displayed, your browser may be blocking content from Twitter. Try turning off content blocking to view images on this page; on Firefox this can be done by clicking on the shield just to the left of the URL and turning off Enhanced Tracking Protection for this site only.]

discovery narrative
Now the author walks us through the story of how scientists discovered why our fingertips wrinkle. To heighten the drama, we get several clues before understanding the entire process.

Tony Breu @tony_breu · Jul 11

6/ A major clue came in 1936 when Lewis and Pickering published their observation that skin innervated by a palsied median nerve failed to wrinkle. This suggested the phenomenon wasn’t simply about water flow, but that it also involved the nervous system. https://t.co/fWZ85C43VA https://t.co/JjOYHEceZY

[Tweet image. If not displayed, your browser may be blocking content from Twitter. Try turning off content blocking to view images on this page; on Firefox this can be done by clicking on the shield just to the left of the URL and turning off Enhanced Tracking Protection for this site only.]

Tony Breu @tony_breu · Jul 11

7/ It appears that nerve activation is essential to water immersion wrinkling. But what does increase nerve firing lead to? Sympathetic mediated vasoconstriction! https://t.co/16WSpF9myW

Tony Breu @tony_breu · Jul 11

8/
The same group that suggested vasoconstriction as a contributor to wrinkling also offered a reason for why we experience it more on the glabrous skin (i.e., smooth/hairless) of the fingertips and toes.

Tony Breu @tony_breu · Jul 11

9/
Two keys regarding fingertip anatomy:

*anchoring of the epidermis to the dermis results in varying skin tautness (max where skin is anchored)
*distal digital pulp has a high concentration of blood vessels and lots of glomus bodies (AV shunts surrounded by connective tissue)

Tony Breu @tony_breu · Jul 11

10/
When glomus bodies lose volume through vasoconstriction, a negative pulp pressure is generated. The result is a downward pull on the overlying skin.

Because dermal anchoring is not uniform in the fingertips, there is variable pull.

Result: WRINKLING!

Tony Breu @tony_breu · Jul 11

11/ In 2004 a more complete mechanism was proposed: water enters via sweat glands ➡️ electrolyte abnormalities ➡️ decreased membrane stability ➡️ increased nerve firing ➡️ vasoconstriction, particularly within dermal pulp ➡️ pull-down of overlying skin ➡️ wrinkles

use case narrative
Here the author goes through how someone might use this information in a clinical setting.

Tony Breu @tony_breu · Jul 11

12/
Is there a way we can make use of this information clinically, or is it just cocktail party fodder?

Well, if a functioning peripheral nerve is required for water immersion wrinkling, maybe its presence/absence can be used to test for neuropathy…

Tony Breu @tony_breu · Jul 11

13/
Since the 1970s, numerous groups have studies exactly this.

It’s been used in diseases causing neuropathies as diverse as diabetes (PMID 6734390) and leprosy (PMID 3006371).

https://t.co/wbjWBdMDv2
https://t.co/0S046esGk1 https://t.co/bH821fa6Yk

[Tweet image. If not displayed, your browser may be blocking content from Twitter. Try turning off content blocking to view images on this page; on Firefox this can be done by clicking on the shield just to the left of the URL and turning off Enhanced Tracking Protection for this site only.] [Tweet image. If not displayed, your browser may be blocking content from Twitter. Try turning off content blocking to view images on this page; on Firefox this can be done by clicking on the shield just to the left of the URL and turning off Enhanced Tracking Protection for this site only.]

Tony Breu @tony_breu · Jul 11

14/
Have you ever used fingertip wrinkling to evaluate nerve function?

payoff
The author gives us the same poll as last time, to check if more people get the correct answer. In the final tweet, the author returns us to the situation in the hook, the three year old asking a question during bath time, and gives us a one-sentence summary that answers the question.

Tony Breu @tony_breu · Jul 11

15/ Before closing, let’s return to the original question: Which of the following contributes to “water immersion wrinkling"?

Tony Breu @tony_breu · Jul 11

16/ Next time my daughter takes a bath, I'll explain that her fingers look like raisins because she has intact sympathetic vasoconstriction with resulting retraction of fingertip pulp and that the density of eccrine sweat glands in her hands contributes. She’s come to expect it.