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UVB Treatment (uvb + treatment)

Distribution by Scientific Domains

Medical Sciences	87%

Selected Abstracts

Solar UVB and warming affect decomposition and earthworms in a fen ecosystem in Tierra del Fuego, Argentina

GLOBAL CHANGE BIOLOGY, Issue 10 2009
JOHANN G. ZALLER
Abstract Combined effects of co-occurring global climate changes on ecosystem responses are generally poorly understood. Here, we present results from a 2-year field experiment in a Carex fen ecosystem on the southernmost tip of South America, where we examined the effects of solar ultraviolet B (UVB, 280,315 nm) and warming on above- and belowground plant production, C : N ratios, decomposition rates and earthworm population sizes. Solar UVB radiation was manipulated using transparent plastic filter films to create a near-ambient (90% of ambient UVB) or a reduced solar UVB treatment (15% of ambient UVB). The warming treatment was imposed passively by wrapping the same filter material around the plots resulting in a mean air and soil temperature increase of about 1.2 °C. Aboveground plant production was not affected by warming, and marginally reduced at near-ambient UVB only in the second season. Aboveground plant biomass also tended to have a lower C : N ratio under near-ambient UVB and was differently affected at the two temperatures (marginal UVB × temperature interaction). Leaf decomposition of one dominant sedge species (Carex curta) tended to be faster at near-ambient UVB than at reduced UVB. Leaf decomposition of a codominant species (Carex decidua) was significantly faster at near-ambient UVB; root decomposition of this species tended to be lower at increased temperature and interacted with UVB. We found, for the first time in a field experiment that epigeic earthworm density and biomass was 36% decreased by warming but remained unaffected by UVB radiation. Our results show that present-day solar UVB radiation and modest warming can adversely affect ecosystem functioning and engineers of this fen. However, results on plant biomass production also showed that treatment manipulations of co-occurring global change factors can be overridden by the local climatic situation in a given study year. [source]

UVB in the management of early stage mycosis fungoides

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 5 2006
F Pavlotsky
Background, Several options for treatment of early mycosis fungoides (MF) offer similar success rates. Previous small studies have shown UVB to be at least as effective as PUVA. Objective, To summarize our experience with UVB treatment of early MF. Methods, A retrospective analysis of early-stage MF patients treated by narrow band (NB) or broad band (BB) UVB in our institution between 1996 and 2002. Most patients achieving complete response (CR) were put on maintenance until natural sun exposure was possible and followed up every 3,6 months. The results were compared to those previously reported regarding PUVA. Results, Sixty-eight and 43 patients were treated by NB and BB UVB, respectively. Eighty-six per cent (84 and 89% in NB and BB UVB groups, respectively) of IA and 71% (78 and 44% in NB and BB UVB groups, respectively) of IB patients achieved CR within a mean of 12.8 and 10.6 weeks, respectively. When maintenance was stopped, 65 and 30% had not relapsed after an average follow up of 27 and 222 weeks, respectively. Non-relapse rate was 33 and 48% for those having had vs. those not having had maintenance, respectively. Conclusions, Our results are comparable to all previously reported for skin-targeted treatments, including PUVA and, to our belief, reflect the nature of early MF, in which CR can probably be achieved in most of the patients. Among the responding patients there is no relapse during prolonged follow-up in about one third of the cases. Thus, we believe treatment should be stopped completely following first CR induction and maintenance treatment should be considered for relapsing patients only. Both broad and narrow UVB options are good and future choices should be made on the basis of short- and long-term side-effects. [source]

Cyclooxygenase-2 deficiency increases epidermal apoptosis and impairs recovery following acute UVB exposure

MOLECULAR CARCINOGENESIS, Issue 5 2007
Jacqueline K. Akunda
Abstract The cyclooxygenases, COX-1 and COX-2, are involved in cutaneous responses to both acute and chronic UV exposure. In the present study, wild-type (WT), COX-1,/, and COX-2,/, mice were used to determine the influence of the individual isoform on mouse skin responses to acute UVB treatment. Immunohistochemistry and Western analysis indicated that COX-2, and not COX-1, was induced by UVB (2.5 or 5.0 kJ/m2), but that COX-1 remained the major source of prostaglandin E2 production. UVB exposure significantly increased epidermal apoptosis in all genotypes compared to untreated mice. However, while the number of apoptotic cells in WT and COX-1,/, mice were about equal, the number of apoptotic cells was 2.5-fold greater in COX-2,/, mice. Apoptosis in WT and COX-2,/, mice peaked at 24 h post-exposure. The increased apoptosis and reduced proliferation in COX-2,/, mice resulted in about a 50% decrease in epidermal thickness at 24,48 h post-exposure compared to about a 50% increase in epidermal thickness in WT mice. UVB-induced cell replication, as measured by BrdU labeling, was reduced in COX-2,/, compared to WT mice at 24,96 h. However, by 96 h post-exposure, both WT and COX-2,/, mice showed epidermal hyperplasia. The data indicate that COX-2 induction initially protects against the acute sunburn effects of UVB, but that continuous induction of COX-2 may contribute to skin cancer in chronic UVB exposure. © 2007 Wiley-Liss, Inc. [source]

AlamarBlue bioassay for cellular investigation of UV-induced crystalline lens damage

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2003
Olanrewaju M. Oriowo
Abstract Purpose: The use of the alamarBlue fluorescence dye for cellular study of UV-induced photodamage in cultured ocular lenses was examined by comparing the results from the fluorometric assay to lens optical quality using a scanning laser system to measure the focal lengths of the lenses following UVB treatment. Methods: Excised porcine lenses were cultured in M199 supplemented with 1% antibiotics and 4% porcine serum. After 1 week of pre-incubation at 37°C, baseline measurements were taken. Treated lenses were irradiated with a range of UVB radiant exposures from 0.019 to 0.076 J cm,2. The lenses were maintained for a further 4 weeks, with measurements carried out every 48 h in the first 9 days post-UVB treatment and then once each week. At each measurement session, treated and control lenses were transferred into a 24-well plate, one lens per well containing the assay. The lenses were incubated for 50 min, after which fluorescence readings were taken with a plate reader. Results: Analyses showed significant (p < 0.05) inhibition of lens metabolic activity and optical function in the 0.038 and 0.076 J cm,2 UVB treated lenses. Lenses treated with 0.019 J cm,2 UVB did not exhibit any photodamage. Conclusions: These results suggest that the alamarBlue assay is useful for the in vitro study of UV-induced lens damage. The decrease in the capacity of treated lenses to reduce alamarBlue over time confirms that UVB photo-oxidation can cause diminution of viable lens epithelial and fibre cells. The results also suggest that the energy threshold for broadband UVB induced cataractogenesis in vitro ranges between 0.019 and 0.038 J cm,2. [source]

The effect of ultraviolet B-induced vitamin D levels on host resistance to Mycobacterium tuberculosis: a pilot study in immigrant Asian adults living in the United Kingdom

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 2 2008
Paul Devakar Yesudian
Summary Asian immigrants to the United Kingdom demonstrate much higher tuberculosis rates than the indigenous population. This is postulated to be because of their low vitamin D levels, consequent upon a combination of diet and their reduced ultraviolet (UV) exposure in the United Kingdom, because vitamin D enhances antimycobacterial activity in in vitro systems. The aim of this study was to examine the relationship between UVB exposure, vitamin D levels and tuberculo-immunity in Asian immigrants in the United Kingdom. Suberythemal UVB treatments were given to eight subjects on 3 consecutive days, using broadband UVB fluorescent lamps. Blood was sampled for 25-hydroxyvitamin D (25-OH D) and whole blood functional assays were performed for antimycobacterial immunity. The mean 25-OH D level increased from a baseline of 11.23 ng/ml (95% CI 6.7,20.39) to 20.39 ng/ml (95% CI 16.6,20) following UVB treatment, P<0.01. However, no significant change in antimycobacterial immunity occurred following UVB exposure. This pilot study in Asian subjects with good baseline tuberculo-immunity has not supported a role for UVB-induced 25-OH D in the immune response to Mycobacterium tuberculosis. [source]

Itch and scratching as predictors of time to clearance of psoriasis with narrow-band ultraviolet B therapy

BRITISH JOURNAL OF DERMATOLOGY, Issue 3 2009
A.W.M. Evers
Summary Background, Narrow-band ultraviolet (UV) B phototherapy is an effective treatment for psoriasis. However, there is considerable variability in the number of treatment sessions needed to achieve psoriasis clearance. While several clinical and treatment-related factors predict time to clearance, the effect of itching and scratching on the number of irradiation sessions is insufficiently understood. Objective, Predictors of the time to clearance were assessed in patients with psoriasis who were referred for UVB treatment in a randomized double-blind comparison of irradiation regimens for UVB phototherapy. Methods, After randomization to either UVB irradiation with a suberythematogenic or an erythematogenic regimen, patients were irradiated with 20% and 40% incremental doses, respectively, three times weekly. The Psoriasis Area and Severity Index (PASI) score was measured at baseline and every 4 weeks, and itching and habitual scratching were measured at baseline. Results, Among the 77 patients who achieved psoriasis clearance (90% reduction of PASI), itching and scratching were correlated with the number of irradiation sessions needed to achieve clearance, with higher levels of itch and scratching predicting more sessions. These effects remained significant after controlling for the initial PASI score, irradiation schemes, minimal erythema dose (MED), skin type, cumulative dose, protocol adjustments and lifestyle factors (smoking habits and alcohol consumption). Conclusions, Patients with higher levels of itch and scratching need more irradiation sessions to achieve clearance of psoriasis with UVB phototherapy. Systematic assessment of the severity of itch and scratching, followed by short-term itch-coping programmes for patients at risk, might be a cost-effective, adjunct to UVB therapy. [source]

The effect of ultraviolet B-induced vitamin D levels on host resistance to Mycobacterium tuberculosis: a pilot study in immigrant Asian adults living in the United Kingdom

A clinical trial and molecular study of photoadaptation in vitiligo

BRITISH JOURNAL OF DERMATOLOGY, Issue 3 2009
C.L. Hexsel
Summary Background, Photoadaptation to ultraviolet (UV) B phototherapy is due to both pigmentary and nonpigmentary influences. Objectives, To measure photoadaptation in vitiliginous skin and to compare it with normal pigmented skin. Methods, Seventeen patients with Fitzpatrick skin phototypes III,VI with vitiligo received six to nine UVB treatments, two to three times weekly. Minimal erythema dose (MED) testing was done at baseline and after all treatments; the percentage change in MED was analysed as a measure of photoadaptation. The percentage decrease in cyclobutane pyrimidine dimers (CPDs) over 24 h after a single exposure of 1 MED was analysed on vitiliginous and normal skin. Results, The mean ± SD percentage change in MED from before to after treatments was: treated vitiliginous skin 28·5 ± 39·9% (P = 0·015), treated normal skin 35·9 ± 49·9% (P = 0·015), untreated vitiliginous skin 11·9 ± 22·6% (P =0·070), untreated normal skin 25·1 ± 41·3% (P = 0·041). Of these patients, two-thirds had a positive percentage change in MED (photoadaptation). The mean amount of CPDs induced per megabase of DNA immediately after exposure was significantly higher in vitiliginous skin. The mean ± SD percentage decrease in CPDs (rate of repair) in 24 h was 35·7 ± 26·8% in vitiliginous skin (P = 0·027) and 46·2 ± 19·5% in normally pigmented skin (P = 0·001); no difference was noted in the repair in vitiliginous skin compared with normal skin (P = 0·4). Conclusions, Photoadaptation in vitiliginous and normal skin was observed in two-thirds of patients. Vitiliginous skin had significantly more CPDs following UVB exposure; the rate of repair of UVB-induced DNA damage was equivalent to that in normal skin. [source]