Biomedical subjects

Lee Ann Applegate

Publications and source records attributed to Lee Ann Applegate.

5 recordsLinked to original sources

PubMed2005

Spectral analysis of laser-induced ultraweak delayed luminescence in cultured normal and tumor human cells: temperature dependence.

The emission spectrum of ultraviolet A laser induced ultraweak delayed luminescence in cell cultures of mammalian cells depended on the temperature during irradiation and photonic measurements. A new method using a sophisticated photomultiplier system was developed in order to find differences between normal and tumor cells. The maximal peak of the emitted light for cultures measured at low temperature of 10 degrees C was near 510 nm in the green visible region while following irradiation at 32 degrees C this maximum was shifted to yellow-orange at 570 nm both in normal and melanoma cells. Overall, this ultraweak photonic model of cultured cells provides to be a new and powerful non-invasive tool for developing new strategies in skin cancer detection.

Adult↗

PubMed2002

Photoprotective potential of lycopene, beta-carotene, vitamin E, vitamin C and carnosic acid in UVA-irradiated human skin fibroblasts.

The photoprotective potential of the dietary antioxidants vitamin C, vitamin E, lycopene, beta-carotene, and the rosemary polyphenol, carnosic acid, was tested in human dermal fibroblasts exposed to ultraviolet-A (UVA) light. The carotenoids were prepared in special nanoparticle formulations together with vitamin C and/or vitamin E. Nanoparticle formulations, in contrast to dimethylsulphoxide, stablized lycopene in the cell culture medium and allowed efficient cellular uptake. The presence of vitamin E in the formulation further increased the stability and cellular uptake of lycopene. UVA irradiation of the human skin fibroblasts led to a 10-15-fold rise in metalloproteinase 1 (MMP-1) mRNA. This rise was suppressed in the presence of low microM concentrations of vitamin E, vitamin C, or carnosic acid but not with beta-carotene or lycopene. Indeed, in the presence of 0.5-1.0 microM beta-carotene or lycopene, the UVA-induced MMP-1 mRNA was further increased by 1.5-2-fold. This increase was totally suppressed when vitamin E was included in the nanoparticle formulation. Heme-oxygenase 1 (HO-1) mRNA expression was strongly induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in this study. Indeed, beta-carotene or lycopene (0.5-1.0 microM) led to a further 1.5-fold rise in the UVA-induced HO-1 mRNA levels. In conclusion, vitamin C, vitamin E, and carnosic acid showed photoprotective potential. Lycopene and beta-carotene did not protect on their own but in the presence of vitamin E, their stability in culture was improved and the rise in MMP-1 mRNA expression was suppressed, suggesting a requirement for antioxidant protection of the carotenoids against formation of oxidative derivatives that can influence the cellular and molecular responses.

Abietanes↗

PubMed2002

Use of sunscreens in families living in Switzerland.

BACKGROUND: The hazards due to sun exposure are well known. Many recent studies have emphasized the protection against the harmful effects of the sun by the use of sunscreens and, moreover, by staying in the shade and wearing long-sleeved shirts, hats and sunglasses. Switzerland has one of the highest rates of skin cancer induction in Europe and the incidence of melanoma in Switzerland is constantly increasing with an incidence of 10-12/100,000 inhabitants/year. Interestingly, some studies have evoked the possibility that sunscreen use can increase the risk of melanoma by increasing overall sun exposure. OBJECTIVE AND METHODS: In this context, the aim of our study was to estimate the amount of sun exposure of children, and their parents, living in Switzerland and to give a description of how they protect themselves against sun irradiation. Questionnaires were provided to pediatricians in every state (canton) in Switzerland and were given to families coming for consultation. RESULTS: A total of 328 forms including 1,285 individuals were returned from most of the cantons in Switzerland. The majority of the Swiss families had 2 children under 16 years of age with middle-aged parents (30-45 years) and a central European skin type (light skin of type II-III, brown or blue eyes, and brown to blond hair). An important sun exposure was noted even though the population seems to be conscious of the associated dangers. Sunscreens were the first-line defense against sun exposure with clothing and shielding oneself from the sun not being highly used. Moreover, sunscreens tended to be misused with most people applying them at the beach or swimming pool (instead of 15 min before exposure) and few applications throughout the day. CONCLUSIONS: Prevention should imperatively be emphasized for lower overall sun exposure as sunscreens are primarily used at the beach and not in routine daily exposure. In addition, it is agreed that prevention campaigns would be better directed towards children because up to 80% of detrimental sun exposure occurs during childhood.

Adolescent↗

PubMedDate not supplied

Tissue engineered fetal skin constructs for paediatric burns.

Autologous skin-grafting is the gold standard for treatment of deep second and third degree burns. Available bioengineered skin products also necessitate this two-step surgical procedure. Therefore, we developed fetal skin constructs to improve healing of such degree burns. A bank of fetal skin cells was developed from one organ donation (4 cm2 of skin allowing the preparation of several million three-dimensional skin constructs, 9x12 cm, on native horse collagen). Successive fetal constructs were applied to eight patients at every change of dressing during 1-3 weeks in an outpatient setting. Complete closure was rapid (mean 15.3 days [SD 5.5]) with little hypertrophy of new skin and no retraction seen. This simple technique provided complete treatment without auto-grafting, showing that fetal skin cells might have great potential to treat burns and eventually acute and chronic wounds of other types.

Burns↗

PubMedDate not supplied

Laser-ultraviolet-A-induced ultraweak photon emission in mammalian cells.

Photobiological research in the last 30 yr has shown the existence of ultraweak photon emission in biological tissue, which can be detected with sophisticated photomultiplier systems. Although the emission of this ultraweak radiation, often termed biophotons, is extremely low in mammalian cells, it can be efficiently increased by ultraviolet light. Most recently it was shown that UV-A (330 to 380 nm) releases such very weak cell radiation in differentiated human skin fibroblasts. Based on these findings, a new and powerful tool in the form of UV-A-laser-induced biophotonic emission of cultured cells was developed with the intention to detect biophysical changes between carcinogenic and normal cells. With suspension densities ranging from 1 to 8 x 10(6) cells/mL, it was evident that an increase of the UV-A-laser-light induced photon emission intensity could be observed in normal as well as melanoma cells. Using this new detection procedure of ultraweak light emission, photons in cell suspensions as low as 100 microL could be determined, which is a factor of 100 lower compared to previous procedures. Moreover, the detection procedure has been further refined by turning off the photomultiplier system electronically during irradiation leading to the first measurements of induced light emission in the cells after less than 10 micros instead of 150 ms, as reported in previous procedures. This improvement leads to measurements of light bursts up 10(7) photons/s instead of several hundred as found with classical designs. Overall, we find decreasing induction ratings between normal and melanoma cells as well as cancer-prone and melanoma cells. Therefore, it turns out that this highly sensitive and noninvasive device enables us to detect high levels of ultraweak photon emission following UV-A-laser-induced light stimulation within the cells, which enables future development of new biophysical strategies in cell research.

Adolescent↗