Säteilyn käyttö ja muu säteilylle altistava toiminta : Vuosiraportti 2018

Vuoden 2018 lopussa ionisoivan säteilyn käyttöä varten oli voimassa 3052 turvallisuuslupaa. Säteilyn käyttöä valvottiin käyttöpaikkoihin tehdyillä säännöllisillä tarkastuksilla, hammasröntgentoimipaikkoihin postitse lähetetyillä testipaketeilla ja annosrekisterin ylläpidolla. Vuonna 2018 Säteilyturvakeskus (STUK) teki 592 turvallisuusluvan alaisen toiminnan tarkastusta. Korjausmääräyksiä annettiin tarkastuksissa 393 kappaletta. Lisäksi julkaistiin säteilyturvallisuusohjeita ja tehtiin valvontaa tukevaa tutkimusta. Annostarkkailussa oli vuonna 2018 yhteensä 12 002 säteilytyötä tekevää työntekijää. Annoskirjauksia tehtiin STUKin ylläpitämään rekisteriin 75 852 kappaletta. Vuonna 2018 ionisoimattoman säteilyn (NIR) käytön valvonta kohdistui lasereihin, solariumeihin, radiolaitteisiin ja kosmeettisiin NIR-sovelluksiin. Valvonnassa puututtiin 45 kertaa vaarallisen laserlaitteen kauppaan tai maahantuontiin. Showlasertarkastuksia tehtiin käyttöpaikoilla 15 kappaletta. Kuntien terveydensuojeluviranomaiset lähettivät tiedot 30 solariumin käyttöpaikkatarkastuksesta STUKin arvioitavaksi ja päätettäväksi. Tämän lisäksi viittä solariumien käyttöpaikkaa valvottiin STUKin oman seurannan perusteella. Mittanormaalitoiminnassa kansallisia mittanormaaleja pidettiin yllä sädehoidon, säteilysuojelun sekä röntgenkuvantamisen säteilymittarien ja ilman radonmittareiden kalibrointeihin. Mittausvertailuissa STUKin tulokset olivat selvästi hyväksyntärajojen sisällä. Vuonna 2018 sattui 110 säteilyn käyttöön liittyvää poikkeavaa tapahtumaa. Tapahtumista 30 koski säteilyn käyttöä teollisuudessa ja tutkimuksessa, 75 säteilyn käyttöä terveydenhuollossa, 2 eläinlääketieteessä ja 3 ionisoimattoman säteilyn käytössä. Terveydenhuollosta ilmoitettiin lisäksi 1149 turvallisuusmerkitykseltään vähäisemmäksi arvioitua tapahtumaa ja läheltä piti -tilannetta. Vuonna 2018 kansalliseen radontietokantaan kirjattiin lähes 8 000 radonmittausta lähes 2 100 työpaikalta. Tavanomaisilla työpaikoilla radonpitoisuus oli suurempi kuin 400 Bq/m³ noin 15 %:ssa mitatuista työpaikoista. Noin 20 %:ssa mitatuista työpaikoista radonpitoisuus oli suurempi kuin uusi viitearvo 300 Bq/m³

Säteilyn käyttö ja muu säteilylle altistava toiminta : Vuosiraportti 2014

Vuoden 2014 lopussa säteilyn käyttöä varten oli voimassa noin 1 800 turvallisuuslupaa. Hammasröntgentoiminta muuttui 1.9.2014 luvanvaraiseksi ja sitä harjoitti noin 1 600 toiminnan harjoittajaa. Säteilyn käyttöä valvottiin käyttöpaikkoihin tehdyillä säännöllisillä tarkastuksilla, hammasröntgentoimipaikkoihin postitse lähetetyillä testipaketeilla ja annosrekisterin ylläpidolla. Vuonna 2014 Säteilyturvakeskus (STUK) teki 757 turvallisuusluvan alaisen toiminnan tarkastusta. Korjausmääräyksiä ja -suosituksia annettiin tarkastuksissa 870 kappaletta. Lisäksi julkaistiin säteilyturvallisuusohjeita ja tehtiin valvontaa tukevaa tutkimusta. Luonnonsäteilyn valvonta (muut paitsi kosminen säteily) siirtyi 1.6.2014 STUKissa Ympäristön valvonta -osastolle. Luonnonsäteilyn valvonnan tulokset raportoidaan tässä julkaisussa. Annostarkkailussa oli vuonna 2014 yhteensä reilut 11 000 säteilytyötä tekevää työntekijää. Annoskirjauksia tehtiin STUKin ylläpitämään rekisteriin 73 585 kappaletta. Vuonna 2014 ionisoimattoman säteilyn (NIR) käytön valvonta kohdistui lasereihin, solariumeihin, radiolaitteisiin ja kosmeettisiin NIR-sovelluksiin. Valvonnassa puututtiin 12 vaarallisen laserlaitteen kauppaan tai maahantuontiin. Showlasertarkastuksia tehtiin käyttöpaikoilla 7 kappaletta. Kuntien terveydensuojeluviranomaiset lähettivät tiedot 20 solariumin käyttöpaikkatarkastuksesta STUKin arvioitavaksi ja päätettäväksi. Tämän lisäksi yksi solariumien käyttöpaikka tarkastettiin paikan päällä. Langattomien päätelaitteiden markkinavalvonnassa testattiin 10 päätelaitetta. Kosmeettisten sovellusten markkinavalvonnassa mitattiin kolme rakennekynsien kovettamiseen tarkoitettua kynsiuunia. Mittanormaalitoiminnassa kansallisia mittanormaaleja pidettiin yllä sädehoidon, säteilysuojelun sekä röntgenkuvantamisen säteilymittarien kalibrointeihin. Mittausvertailuissa STUKin mittanormaalilaboratorion tulos oli selvästi hyväksyntärajojen sisällä. Ulkoisissa arvioinneissa laboratorion todettiin täyttävän kansalliselle mittanormaalilaboratoriolle asetetut vaatimukset. Vuonna 2014 sattui 138 säteilyn käyttöön liittyvää poikkeavaa tapahtumaa. Tapahtumista 38 koski säteilyn käyttöä teollisuudessa, tutkimuksessa ja opetuksessa, 96 säteilyn käyttöä terveydenhuollossa, yksi eläinlääketieteessä ja kolme ionisoimattoman säteilyn käytössä

Radiation practices : Annual report 2014

1800 safety licences for the use of radiation were current at the end of 2014. On 1 September 2014, dental X-ray practices became subject to a safety licence and were practiced by 1600 responsible parties (parties running a radiation practice). The use of radiation was controlled through regular inspections performed at places of use, test packages sent by post to dental X-ray facilities and maintenance of the Dose Register. The Radiation and Nuclear Safety Authority (STUK) conducted 757 inspections of licensed practices in 2014. 870 repair orders and recommendations were issued during the course of inspections. Radiation safety guides were also published and research was conducted in support of regulatory control. The regulatory control of natural radiation (excluding cosmic radiation) was transferred to the Department of Environmental Radiation Surveillance at STUK on 1 June 2014. The reports on the regulatory control of natural radiation are reported in this publication. A total of over 11 000 workers engaged in radiation work were subject to individual monitoring in 2014, and 73 585 dose entries were made in the Dose Register maintained by STUK. In 2014, regulatory control of the use of non-ionising radiation (NIR) focused particularly on lasers, sunbeds, radio appliances and cosmetic applications producing non-ionising radiation. A total of 12 cases of sales or importation of dangerous laser devices were found in regulatory control. The number of show laser on-site inspections was seven. Municipal health protection authorities submitted the details of the inspections of 20 sunbed facilities to STUK for evaluation and decision. In addition to this, one sunbed facility was inspected on-site. In the market control of wireless communication devices, 10 devices were tested. In the market control of cosmetic applications, measurements were taken of three nail ovens used for curing nail enhancements. In metrological activities, national metrological standards were maintained to the calibrations of the radiation meters for radiotherapy, radiation protection and X-ray imaging. STUK’s metrological laboratory was found to be well within the acceptable variation of results in the measurement comparison. In external evaluations, the laboratory was found to comply with the requirements set for national metrological laboratories. There were 138 abnormal events related to radiation use in 2014. 38 of the events dealt with the use of radiation in industry, research and education, 96 with the use of radiation in health care, one in veterinary medicine, and three with the use of non-ionising radiation

Radiation practices : Annual report 2015

Some 3200 safety licences for the use of radiation were current at the end of 2015, including licences granted to dental X-ray practices (approx. 1600), which became subject to a licence on 1 September 2014. The use of radiation was controlled through regular inspections performed at places of use, test packages sent by post to dental X-ray facilities and maintenance of the Dose Register. The Radiation and Nuclear Safety Authority (STUK) conducted 599 inspections of safety-licensed practices in 2015. Over the course of the inspections, 726 repair orders were issued. Radiation safety guides were also published and research was conducted in support of regulatory control. A total of over 10 800 workers engaged in radiation work were subject to individual monitoring in 2015, and nearly 69 000 dose entries were made in the Dose Register maintained by STUK. In 2015, regulatory control of the use of non-ionizing radiation (NIR) focused particularly on lasers, sunbeds, radio appliances and cosmetic applications utilizing non-ionizing radiation. A total of 18 cases of sales or importation of dangerous laser devices were found in regulatory control. Seven on-site inspections of show lasers were conducted. Municipal health protection authorities submitted the details of the inspections of 17 sunbed facilities to STUK for evaluation and decision. In addition to this, four sunbed facilities were inspected on-site. In the market surveillance of wireless communication devices, 14 devices were tested. In metrological activities, national metrological standards were maintained to the calibrations of the radiation meters for radiotherapy, radiation protection and X-ray imaging. STUK’s metrological laboratory performed well in the measurement comparisons where STUKs results clearly fullfilled the acceptance criteria.. In external evaluations, the laboratory was found to comply with the requirements set for national metrological laboratories. There were 98 abnormal events related to radiation use in 2015. Thirty of the cases dealt with the use of radiation in industry and research, 64 with the use of radiation in health care, and four with non-ionizing radiation. Furthermore, 755 events with an estimated lower safety significance were reported in regards to health care

Radiation practices : Annual report 2018

A total of 3052 safety licences for the use of ionizing radiation were current at the end of 2018. The use of radiation was controlled through regular inspections performed at places of use, test packages sent by post to dental X-ray facilities and maintenance of the Dose Register. The Radiation and Nuclear Safety Authority (STUK) conducted 592 inspections of safetylicensed practices in 2018. The inspections resulted in 393 repair orders issued. In addition, radiation safety guides were published and research was conducted in support of regulatory control. A total of 12 002 occupationally exposed workers were subject to individual monitoring in 2018. 75 852 dose entries were recorded in the Dose Register maintained by STUK. In 2018, regulatory control of the use of non-ionizing radiation (NIR) focused on laser equipment, sunbeds, radio appliances and cosmetic NIR applications. Forty-five cases of sales or import of dangerous laser devices were found through regulatory control. Fifteen on-site inspections of show lasers were conducted. Municipal health protection authorities submitted the details of the inspections of 30 sunbed facilities to STUK for evaluation and decision. In addition to this, five sunbed facilities were surveyed on the basis of STUK’s own monitoring. In metrological activities, national metrological standards were maintained for the calibration of radiation meters used in radiotherapy, radiation protection and X-ray imaging as well as the calibration of radon meters used for measurement of radon in air. In measurement comparisons, STUK’s results were clearly within the acceptable range. There were 110 abnormal events related to radiation use in 2018. Of these events, 30 concerned the use of radiation in industry and research, 75 the use of radiation in health care, two the use of radiation in veterinary practices and three the use of non-ionizing radiation. In addition, 1149 events and near misses with an estimated minor significance for safety were reported for health care. In 2018, nearly 8000 radon measurements at nearly 2100 workplaces were recorded in the national radon database. At conventional workplaces, the radon concentration exceeded 400 Bq/m3 at approximately 15 per cent of the measured workplaces. The radon concentration exceeded the new reference value of 300 Bq/m3 at approximately 20 per cent of the measured workplaces

Pitkäaaltoisen UV-säteilyn vaikutus hiiren melanoomaan in vitro ja in vivo

The skin cancer incidence has increased substantially over the past decades and the role of ultraviolet (UV) radiation in the etiology of skin cancer is well established. Ultraviolet B radiation (280-320 nm) is commonly considered as the more harmful part of the UV-spectrum due to its DNA-damaging potential and well-known carcinogenic effects. Ultraviolet A radiation (320-400 nm) is still regarded as a relatively low health hazard. However, UVA radiation is the predominant component in sunlight, constituting more than 90% of the environmentally relevant solar ultraviolet radiation. In the light of the recent scientific evidence, UVA has been shown to have genotoxic and immunologic effects, and it has been proposed that UVA plays a significant role in the development of skin cancer. Due to the popularity of skin tanning lamps, which emit high intensity UVA radiation and because of the prolonged sun tanning periods with the help of effective UVB blockers, the potential deleterious effects of UVA has emerged as a source of concern for public health. The possibility that UV radiation may affect melanoma metastasis has not been addressed before. UVA radiation can modulate various cellular processes, some of which might affect the metastatic potential of melanoma cells. The aim of the present study was to investigate the possible role of UVA irradiation on the metastatic capacity of mouse melanoma both in vitro and in vivo. The in vitro part of the study dealt with the enhancement of the intercellular interactions occurring either between tumor cells or between tumor cells and endothelial cells after UVA irradiation. The use of the mouse melanoma/endothelium in vitro model showed that a single-dose of UVA to melanoma cells causes an increase in melanoma cell adhesiveness to non-irradiated endothelium after 24-h irradiation. Multiple-dose irradiation of melanoma cells already increased adhesion at a 1-h time-point, which suggests the possible cumulative effect of multiple doses of UVA irradiation. This enhancement of adhesiveness might lead to an increase in binding tumor cells to the endothelial lining of vasculature in various internal organs if occurring also in vivo. A further novel observation is that UVA induced both decline in the expression of E-cadherin adhesion molecule and increase in the expression of the N-cadherin adhesion molecule. In addition, a significant decline in homotypic melanoma-melanoma adhesion (clustering) was observed, which might result in the reduction of E-cadherin expression. The aim of the in vivo animal study was to confirm the physiological significance of previously obtained in vitro results and to determine whether UVA radiation might increase melanoma metastasis in vivo. The use of C57BL/6 mice and syngeneic melanoma cell lines B16-F1 and B16-F10 showed that mice, which were i.v. injected with B16-F1 melanoma cells and thereafter exposed to UVA developed significantly more lung metastases when compared with the non-UVA-exposed group. To study the mechanism behind this phenomenon, the direct effect of UVA-induced lung colonization capacity was examined by the in vitro exposure of B16-F1 cells. Alternatively, the UVA-induced immunosuppression, which might be involved in increased melanoma metastasis, was measured by standard contact hypersensitivity assay (CHS). It appears that the UVA-induced increase of metastasis in vivo might be caused by a combination of UVA-induced systemic immunosuppression, and to the lesser extent, it might be caused by the increased adhesiveness of UVA irradiated melanoma cells. Finally, the UVA effect on gene expression in mouse melanoma was determined by a cDNA array, which revealed UVA-induced changes in the 9 differentially expressed genes that are involved in angiogenesis, cell cycle, stress-response, and cell motility. These results suggest that observed genes might be involved in cellular response to UVA and a physiologically relevant UVA dose have previously unknown cellular implications. The novel results presented in this thesis offer evidence that UVA exposure might increase the metastatic potential of the melanoma cells present in blood circulation. Considering the wellknown UVA-induced deleterious effects on cellular level, this study further supports the notion that UVA radiation might have more potential impact on health than previously suggested. The possibility of the pro-metastatic effects of UVA exposure might not be of very high significance for daily exposures. However, UVA effects might gain physiological significance following extensive sunbathing or solaria tanning periods. Whether similar UVA-induced pro-metastatic effects occur in people sunbathing or using solaria remains to be determined. In the light of the results presented in this thesis, the avoidance of solaria use could be well justified.Ihosyöpien ilmaantuvuus on lisääntynyt voimakkaasti viimeisten vuosikymmenten aikana ja ultraviolettisäteilyn (UV-säteilyn) vaikutus ihosyöpien ilmaantuvuuteen on kiistaton. Ultravioletti B -säteily (280-320 nm) on tunnetusti haitallista DNA:ta vaurioittavien ja karsinogeenisten vaikutustensa vuoksi. Ultravioletti A -säteilyn (320-400 nm) terveysvaikutuksia on puolestaan pidetty pitkään harmittomampana kuin UVB-säteilyn vaikutuksia. Maanpinnalle saapuvasta auringonvalosta kuitenkin yli 90% on UVA-säteilyä. Viimeaikaisten tutkimustulosten perusteella UVA-säteilyllä on kuitenkin havaittu olevan perimää vaurioittavia ja immunologisia vaikutuksia ja lisäksi sillä saattaa olla myös merkittävä rooli ihosyöpien kehittymisessä. UVA-säteilyaltistuksen aiheuttamat epäsuotuisat terveysvaikutukset ovat nousseet huolenaiheeksi ihmisten ruskettaessa itseään solariumeissa, jotka säteilevät voimakasta UVA-säteilyä, tai ottaessa pitkiä aikoja aurinkoa tehokkaiden UVB-aurinkosuojien turvin, jotka suojelevat ihoa tehokkaasti UVB-säteilyn aiheuttamalta palamiselta suojaten kuitenkin ihoa vähemmän UVA-säteilyltä. UV-säteilyn vaikutuksia melanooman kykyyn lähettää etäpesäkkeitä ei ole tutkittu aikaisemmin. UVA-säteilyn on kuitenkin havaittu aiheuttavan soluissa monia sellaisia fysiologisia muutoksia, jotka saattavat lisätä syöpäsolujen taipumusta lähettää etäpesäkkeitä (syövän metastasointi). Tämän väitöstutkimuksen tarkoituksena oli tarkastella UVA-säteilyn vaikutusta hiiren melanoomasolujen metastaattisiin ominaisuuksiin. Soluviljelmin tehdyissä tutkimuksissa tarkasteltiin UVA-säteilyn vaikutusta melanoomasolujen ja endoteelisolujen väliseen sitoutumiseen. UVA-säteilyn havaittiin lisäävän melanoomasolujen sitoutumista säteilyttämättömiin endoteelisoluihin, mutta samanaikaisesti melanoomasolujen keskinäinen sitoutuminen kuitenkin toisiinsa väheni. Nämä seikat saattavat lisätä melanoomasolujen metastaasitaipumusta tapahtuessaan elävässä organismissa. Tästä syystä saatuja tuloksia tarkasteltiin hiirimallissa, jossa tutkittiin, ovatko solulinjoilla tehdyt havainnot muutoksista melanoomasolujen adhesiivisuudessa fysiologisesti merkittäviä ja sitä, lisääkö UVA-säteily melanooman etäpesäkkeiden muodostumista hiirissä. UVA-säteilyn havaittiin lisäävän keuhkometastaasien määrää UVA-käsitellyissä hiirissä verrattuna kontrolliryhmään, jotka eivät olleet saaneet säteilyä. Tutkimusten mukaan UVA-säteilyn kyky lisätä hiiren melanoomasolujen metastaattista aktiivisuutta saattaa johtua sekä UVA-säteilyn suorista vaikutuksista melanoomasoluihin ja myös sen aiheuttamasta immunosuppressiosta. Tutkimuksessa tarkasteltiin myös UVA-säteilyn vaikutusta hiiren melanoomasolujen geenien ilmentymiseen. UVA-säteilyn havaittiin muuttavan yhdeksän geenin ilmenemisprofiilia melanoomasoluissa säteilytyksen jälkeen. Näiden tulosten perusteella havaittujen geenien voidaan arvella olevan osa UVA-säteilyn aiheuttamaa soluvastetta ja sen lisäksi osa UVA-säteilyn aiemmin tuntemattomia vaikutuksia soluissa. Tässä väitöstutkimuksessa on osoitettu ensimmäistä kertaa, että UVA-säteily saattaa lisätä verenkierrossa olevien melanoomasolujen metastaattista kapasiteettia. Nämä tulokset tukevat aiempien tutkimustulosten näkemystä siitä, että UVA-säteilyllä saattaa olla enemmän terveysvaikutuksia kuin aiemmin on osattu epäillä. Jokapäiväisessä elämässä UVA-säteilyn vaikutukset ovat pieniä, mutta ne saattavat olla merkityksellisiä solariumia käytettäessä tai otettaessa pitkään aurinkoa, jolloin altistuminen UVA-säteilylle on voimakasta. UVA-säteilyn vaikutukset ihmisen melanooman kykyyn lähettää etäpesäkkeitä jää vielä selvitettäväksi. Tämän tutkimuksen perusteella solariumin käytön välttäminen saattaa kuitenkin olla aiheellista

Ultraviolet-A radiation induces changes in cyclin G gene expression in mouse melanoma B16-F1 cells

<p>Abstract</p> <p>Background</p> <p>We have previously shown that ultraviolet-A (UVA) radiation enhances metastatic lung colonization capacity of B16-F1 melanoma cells. The aim of this study was to examine changes in expression profile of genes in mouse melanoma B16-F1 cells exposed to UVA radiation.</p> <p>Results</p> <p>B16-F1 melanoma cells were exposed to a single UVA radiation dose of 8 J/cm²and mRNA was isolated 4 h after the end of UVA exposure. Atlas™ Mouse Cancer 1.2 cDNA expression arrays were used for the large-scale screening to identify the genes involved in the regulation of carcinogenesis, tumor progression and metastasis. Physiologically relevant UVA dose induced differential expression in 9 genes in the UVA exposed melanoma cells as compared to the unexposed control cells. The expression of seven genes out of nine was upregulated (HSC70, HSP86, α-B-crystallin, GST mu2, Oxidative stress induced protein OSI, VEGF, cyclin G), whereas the expression of two genes was down-regulated (G-actin, non-muscle cofilin). The gene expression of cyclin G was mostly affected by UVA radiation, increasing by 4.85-folds 4 hour after exposure. The analysis of cyclin G protein expression revealed 1.36-fold increase at the 6 hour time point after UVA exposure. Cell cycle arrest in G2/M phase, which is known to be regulated by cyclin G, occurred at 4-h hour time-point, peaking 8 hours after the end of UVA irradiation, suggesting that cyclin G might play a role in the cell cycle arrest.</p> <p>Conclusion</p> <p>Our results suggest that UVA radiation-induces changes in the expression of several genes. Some of these changes, e.g. in expression of cyclin G, possibly might affect cell physiology (cell cycle arrest).</p

Radiation practices : Annual report 2017

A total of 3086 safety licences for the use of ionizing radiation were current at the end of 2017. The use of radiation was controlled through regular inspections performed at places of use, test packages sent by post to dental X-ray facilities and maintenance of the Dose Register. The Radiation and Nuclear Safety Authority (STUK) conducted 584 inspections of safety-licensed practices in 2017. The inspections resulted in 687 repair orders issued. In addition, radiation safety guides were published and research was conducted in support of regulatory control. A total of 11 381 occupationally exposed workers were subject to individual monitoring in 2017 and 70 536 dose entries were recorded in the Dose Register maintained by STUK. In 2017, regulatory control of the use of non-ionizing radiation (NIR) focused on lasers, sunbeds, radio appliances and cosmetic NIR applications. Two cases of sales or import of dangerous laser devices were found through regulatory control. Fifteen on-site inspections of show lasers were conducted. Municipal health protection authorities submitted the details of the inspections of 31 sunbed facilities to STUK for evaluation and decision. In addition to this, six sunbed facilities were surveyed on the basis of STUK’s own monitoring. In metrological activities, national metrological standards were maintained for the calibration of radiation meters used in radiotherapy, radiation protection and X-ray imaging as well as the calibration of radon meters used for measurement of radon in air. In measurement comparisons, STUK’s results were clearly within the acceptable range. There were 112 abnormal events related to radiation use in 2017. Of these events, 25 concerned the use of radiation in industry and research, 84 the use of radiation in health care and three the use of non-ionizing radiation. In addition, 1085 events and near misses with an estimated minor significance for safety were reported for health care. In 2017, nearly 7800 radon measurements at over 2000 workplaces were recorded in the national radon database. Radon concentrations detected in workplace measurements reported to STUK have decreased from the previous years. At conventional workplaces, the 400 Bq/m3 radon concentration was exceeded at approximately 13 per cent of the measured workplaces

In vivo UVA irradiation of mouse is more efficient in promoting pulmonary melanoma metastasis than in vitro

<p>Abstract</p> <p>Background</p> <p>We have previously shown <it>in vitro </it>that UVA increases the adhesiveness of mouse B16-F1 melanoma cells to endothelium.</p> <p>We have also shown <it>in vivo </it>that UVA exposure of C57BL/6 mice, <it>i.v</it>. injected with B16-F1 cells, increases formation of pulmonary colonies of melanoma. The aim of the present animal study was to confirm the previously observed <it>in vivo </it>UVA effect and to determine whether <it>in vitro </it>UVA-exposure of melanoma cells, prior the <it>i.v</it>. injection, will have an enhancing effect on the pulmonary colonization capacity of melanoma cells. As a second aim, UVA-derived immunosuppression was determined.</p> <p>Methods</p> <p>Mice were <it>i.v</it>. injected with B16-F1 cells into the tail vein and then immediately exposed to UVA. Alternatively, to study the effect of UVA-induced adhesiveness on the colonization capacity of B16-F1 melanoma, cells were <it>in vitro </it>exposed prior to <it>i.v</it>. injection. Fourteen days after injection, lungs were collected and the number of pulmonary nodules was determined under dissecting microscope. The UVA-derived immunosuppression was measured by standard contact hypersensitivity assay.</p> <p>Results and Discussion</p> <p>Obtained results have confirmed that mice, <it>i.v</it>. injected with B16-F1 cells and thereafter exposed to UVA, developed 4-times more of melanoma colonies in lungs as compared with the UVA non-exposed group (p < 0.01). The <it>in vitro </it>exposure of melanoma cells prior to their injection into mice, led only to induction of 1.5-times more of pulmonary tumor nodules, being however a statistically non-significant change. The obtained results postulate that the UVA-induced changes in the adhesive properties of melanoma cells do not alone account for the 4-fold increase in the pulmonary tumor formation. Instead, it suggests that some systemic effect in a mouse might be responsible for the increased metastasis formation. Indeed, UVA was found to induce moderate systemic immunosuppression, which effect might contribute to the UVA-induced melanoma metastasis in mice lungs.</p

Imaging leukocyte trafficking in vivo with two-photon-excited endogenous tryptophan fluorescence

We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore. Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium. Inflammation significantly enhances leukocyte rolling, adhesion, and tissue infiltration. After exiting the vasculature, leukocytes continue to move actively in tissue as observed by time-lapse microscopy, and are distinguishable from resident autofluorescent cells that are not motile. Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans