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By Vijay Kumar Malesu Feb 14 2024 Reviewed by Lily Ramsey, LLM

In a recent study published in Scientific Reports, a group of researchers evaluated how melanin content and distribution affect ultraviolet (UV)-induced deoxyribonucleic acid (DNA) damage in skin, using reconstructed human epidermis (RHE) models.

Study:  Significance of melanin distribution in the epidermis for the protective effect against UV light . Image Credit: rangizzz/Shutterstock.com Background 

While ultraviolet radiation (UVR) is crucial for vitamin D and endorphins, its overexposure increases the risk of skin cancer through DNA damage.

This damage occurs via UV-B absorption and UV-A-induced radicals, leading to specific DNA lesions. Thanks to melanin, skin pigmentation offers substantial photoprotection, notably reducing cancer rates in darker skin.

Melanin's effectiveness is attributed to its UV-blocking, antioxidant, and radical-neutralizing properties. Nonetheless, the role of melanin is complex, as it may also enhance cell sensitivity to UVR damage.

This contradiction prompts a need for further research to understand melanin's dual effects on photoprotection and photosensitization in skin cancer dynamics. About the study 

In the present study, RHE models developed from primary epidermal keratinocytes and melanocytes of Asian-Caucasian and Afro-American donors were categorized into tanned and light based on their melanin content, established through a newly validated method on ex vivo human skin.

This method involved melanin extraction and spectrometric analysis at 500 nm wavelength, correlating melanin levels with the Individual Typological Angle (ITA°), a measure of skin pigmentation.

Ex vivo human skin samples, sourced from healthy individuals of various ethnic backgrounds undergoing surgery, were used to calibrate the melanin quantification process. These samples allowed researchers to classify the RHE models according to melanin content, facilitating a comparison between light and tanned models. Related StoriesGenetics of estrogen production linked to endometrial cancer risk in postmenopausal womenPlant-based diet linked to less erectile dysfunction, urinary incontinence in prostate cancer patientsTiny device could help improve safety, effectiveness of cell therapy for spinal cord injury patients

The study assessed DNA damage in these models following UV irradiation, employing immunohistochemical staining to quantify damage.

Additionally, the effect of UV exposure on radical formation was examined using Electron Paramagnetic Resonance (EPR) spectroscopy, revealing insights into the oxidative stress induced by UV light in different melanin concentrations.

A critical aspect of the research was investigating melanin distribution within the epidermis, utilizing techniques like Fontana-Masson staining and Two-Photon Excited Fluorescence Lifetime Imaging Microscopy (TPE-FLIM).

These methods provided a detailed view of melanin's localization, contributing to understanding its protective versus potential photosensitizing effects. Study results 

After extracting melanin from human epidermis samples and RHE, researchers quantified the total melanin content spectrometrically by measuring absorbance at 500 nm.

In ex vivo skin samples, melanin content varied significantly, correlating strongly with the skin's ITA°, indicating a methodological validation. This approach was then applied to RHE, revealing distinct melanin levels between tanned and light models.

The correlation between melanin content and ITA° was used to categorize RHE models by skin color, confirming the method's applicability across different epidermal sources.

The study further evaluated DNA damage through immunohistochemical staining, quantifying the extent of damage by the presence of cyclobutane-pyrimidine dimers (CPD) in cells post-UVR exposure.

Results showed significant DNA damage across all RHE models immediately after exposure, with variances in damage levels based on the type of UVR and the model's pigmentation.

Notably, tanned RHE models exhibited more damage than light ones, especially after specific types of UV irradiation. This damage assessment highlighted potential photoprotection discrepancies tied to melanin content and distribution.

Additionally, the research investigated radical formation post-irradiation, finding that tanned RHE models produced more free radicals than light models under certain conditions, suggesting melanin's complex role in the skin's response to UV exposure.

Contrary to in vivo skin, where melanin typically encapsulates keratinocyte nuclei, providing a protective barrier, tanned RHE models displayed a non-homogeneous melanin distribution. This misallocation potentially undermines melanin's protective efficacy against UVR.

The examination extended to the melanin coverage within basal cells, revealing a stark contrast between in vivo conditions and tanned RHE models.

In vivo, melanin distribution was relatively uniform across different skin types, whereas tanned RHE showed minimal melanin presence, diverging significantly from expected patterns. This inconsistency underscores a fundamental difference in melanin's protective mechanism in vitro versus in vivo. Conclusions 

To summarize, melanin plays a dual role in the human body, acting as a skin pigment that protects against solar radiation while also exhibiting photosensitizing properties linked to skin pathologies like melanoma.

This complex molecule's protective and harmful effects on the skin are still not fully understood.

Research using reconstructed RHE of tanned and light skin types has sought to delve deeper into melanin's multifaceted roles, examining how melanin content and distribution influence UV-induced DNA damage and the generation of reactive oxygen species (ROS).

These studies have shown that despite higher melanin levels in tanned models suggesting greater protection, all models exhibited significant DNA damage following UV exposure, challenging the notion of melanin's protective efficacy.

The distribution of melanin, particularly its concentration in certain cells and absence in others, may contribute to its photosensitizing effects, leading to increased free radical production and DNA damage.  Journal reference:

Zamudio Díaz, D.F., Busch, L., Kröger, M. et al. (2024) Significance of melanin distribution in the epidermis for the protective effect against UV light. Sci Rep. doi: https://doi.org/10.1038/s41598-024-53941-0. https://www.nature.com/articles/s41598-024-53941-0 

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UK

VE Day: Veterans to join King for tea party as Keir Starmer praises ‘selfless dedication’

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VE Day: Veterans to join King for tea party as Keir Starmer praises 'selfless dedication'

Veterans are set to join the King for a VE Day tea party today as the prime minister has paid tribute to the “selfless dedication” of the war generation.

Among them will be a 99-year-old who took part in the D-Day landings and a 100-year-old woman who worked in the Special Operations Executive, known as Churchill’s Secret Army.

Director general of the Royal British Legion, Mark Atkinson, said the charity was “proud” to be taking a place “at the heart of these national celebrations and commemorations” on the 80th anniversary of the end of the Second World War.

He said it would be “one of our last opportunities as a nation to pay tribute to those veterans still with us today”.

Evacuees from World War Two and veterans who were still in active conflict after VE Day are among the other guests set to attend the tea party, which will take place in the presence of the King and other members of the Royal Family.

The Royal Family will watch a millitary procession and flypast on Monday. File pic: PA
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The Royal Family will watch a military procession and flypast on Monday. File pic: PA

At 12pm, the Royal Family will observe a military procession, followed by a flypast.

It will be the first major VE Day anniversary without any of the royals who stood on the balcony of Buckingham Palace on the day victory in Europe was declared, after the death of the late Queen Elizabeth II in 2022.

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‘Not just for Britain’

The celebrations come as Prime Minister Sir Keir Starmer praised veterans for their “selfless dedication” and thanked them for a “debt that can never fully be repaid” in an open letter ahead of VE Day.

He said the stories which will be heard this week from those who fought in the Second World War would be a reminder that the victory “was not just for Britain” but was also “a victory for good against the assembled forces of hatred, tyranny and evil”.

Sir Keir said the WW2 veterans “represent the best of who we are” and that without their service “the freedom, peace and joy that these celebrations embody, would not be possible”.

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VE Day veteran tells Sky News what the atmosphere was like when WWII was finally declared over in Europe

Personnel from NATO allies the US, France and Germany will be among those taking part in the procession in London.

The commemorations will begin with the words of Sir Winston Churchill‘s 1945 victory speech, spoken by actor Timothy Spall.

Thousands of people are expected to line the streets of the capital to witness the celebrations.

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Codebreaker’s ‘special’ encounter with Churchill

Read more:
What’s happening to mark the 80th anniversary of VE Day?
When and where to watch VE Day flypast
Augmented reality brings to life the stories of VE Day 80 years on

On the anniversary itself on Thursday, marking exactly 80 years since the Allies formally accepted Germany’s surrender, a service of commemoration will be held at Westminster Abbey, to include a national two minutes’ silence.

Pubs across England and Wales, which usually close at 11pm, will also stay open for an extra two hours to allow punters more time to celebrate.

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Sports

Logano gets 1st win this season in OT at Texas

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Logano gets 1st win this season in OT at Texas

FORT WORTH, Texas — Reigning NASCAR Cup champion Joey Logano overcame a lot to get his first victory this season.

It came a week after Team Penske teammate Austin Cindric‘s win at Talladega, where Logano had a fifth-place finish that became 39th after a postrace inspection found an issue with the spoiler on his No. 22 Ford. There was also Logano’s expletive-laden rant on the radio toward his teammate in the middle of that race that the two smoothed out during the week. Oh, and he started 27th at Texas after a bad qualifying effort on the 1½-mile track.

But Logano surged ahead on the restart in overtime Sunday to win in the 11th race this year. He led only seven of the 271 laps, four more than scheduled.

“After what happened last week, to be able to rebound and come right back, it’s a total ’22’ way of doing things. So proud of the team,” Logano said.

On the final restart after the 12th caution, Logano was on the inside of his other teammate, Ryan Blaney. But Logano pulled away on the backstretch and stayed easily in front for the final 1½ laps, while Ross Chastain then passed Blaney to finish second ahead of him.

“Just slowly, methodically,” Logano said of his progression to the front. “Just kept grinding, a couple here and a couple there and eventually get a win here.”

Logano got his 37th career victory, getting the lead for the first time on Lap 264. He went low to complete a pass of Michael McDowell.

“I mean, there’s always a story next week, right?” Logano said. “So I told my wife last week before we left, I said, ‘Watch me go win this one.’ It’s just how we do stuff.”

On a caution with 47 laps left, McDowell took only two tires and moved up 15 spots to second. He ended up leading 19 laps, but got loose a few laps after getting passed by Logano and crashed to bring out the caution that sent the race to overtime. He finished 26th.

“We were giving it everything we had there to try to keep track position,” McDowell said. “Joey got a run there, and I tried to block it. I went as far as I think you could probably go. When Blaney slid in front of me, it just took the air off of it and I just lost the back of it. I still had the fight in me, but I probably should have conceded at that point.”

Odds and Ends

William Byron, Kyle Larson, Denny Hamlin and Chase Elliott remained the top four in season points. … Elliott left Texas last spring with his first victory after 42 races and 18 months without one. He hasn’t won since, and now has another long winless drought — this one 38 races and nearly 13 months after finishing 16th. … A crew member for Christopher Bell crawled in through the passenger side of the No. 20 Joe Gibbs Racing Toyota and was fully in the car to reconnect an air hose to the driver’s helmet during a caution in the second stage. It took two stops during that caution, and twice climbing into the car, to resolve the issue.

Fiery end to Hamlin streak

Hamlin had finished on the lead lap in 21 consecutive races, but a fiery finish on Lap 75 ended that streak that had matched the eighth longest in NASCAR history. He was the first car out of the race.

After the No. 11 Joe Gibbs Racing Toyota lost power, something blew up when Hamlin recycled the engine. Flames were coming from under the car and it was engulfed in smoke when it rolled to a stop on the inside of the track, and Hamlin climbed out unharmed.

Youngest pole sitter

Carson Hocevar, the 22-year-old driver who is McDowell’s teammate with Spire Motorsports, was the youngest pole sitter in Texas. He led only the first 22 laps of the race, losing it while pitting during the first caution. He finished 24th after a late accident.

Stage cautions

Both in-race stages finished under caution. Cindric won Stage 1 after Hamlin’s issues, and Kyle Larson took the second after a yellow flag came out because of debris on the track after the right rear tire on Chris Buescher‘s car came apart.

Larson got his 68th overall stage win and his sixth at Texas, with both marks being records. He has won a stage in each of the past five Cup races at Texas, starting in his 2021 win there.

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US

Trump calls for reopening of Alcatraz to house ‘most ruthless and violent offenders’

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Trump calls for reopening of Alcatraz to house 'most ruthless and violent offenders'

US President Donald Trump has called for the reopening of notorious prison Alcatraz.

In a post on his social media site Truth Social, Mr Trump said America had been “plagued by vicious, violent, and repeat criminal offenders”.

He added that when the United States was “a more serious nation” it “did not hesitate to lock up the most dangerous criminals”.

“That is why, today, I am directing the Bureau of Prisons, together with the Department of Justice, FBI, and Homeland Security, to reopen a substantially enlarged and rebuilt Alcatraz, to house America’s most ruthless and violent offenders,” he wrote.

Mr Trump said the reopening of the San Francisco prison would “serve as a symbol of law, order, and justice”.

The US president’s latest policy announcement comes after he fired national security adviser Mike Waltz last week in the first major change to his administration.

US President Donald Trump. Pic: AP
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US President Donald Trump speaking to reporters on Sunday. Pic: AP

Alcatraz was infamously inescapable and in the 29 years it was open, 36 men attempted 14 separate escapes, according to the FBI.

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Nearly all of them were caught or did not survive the attempt at escaping.

The prison housed some of America’s most notorious criminals, including Al Capone and George Kelly.

It has also been the subject of a number of films, including The Rock, starring Sean Connery and Nicolas Cage.

Alcatraz Island. File pic: AP
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Alcatraz Island. File pic: AP

Alcatraz Island, which is surrounded by strong ocean currents and cold Pacific waters, is now a major tourist site, operated by the National Park Service.

The prison’s closure in 1963 was attributed to crumbling infrastructure and high repair costs.

A spokesperson for the Bureau of Prisons said it would “comply with all presidential orders”.

The Bureau of Prisons currently has 16 high-security prisons, including its maximum-security facility in Florence, Colorado, and a facility in Terre Haute, Indiana, which is home to the federal death chamber.

The United States’ federal law enforcement agency has been the subject of increased scrutiny in recent years after Jeffrey Epstein‘s suicide at a federal jail in New York City in 2019.

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