Immunologically mediated skin disorders
Anupam Das, Sumit Sethi in Concise Dermatology, 2021
Urticaria is characterized by transient, superficial well-defined pruritic wheals of the skin, whereas angioedema involves oedema of the dermis and subcutaneous or submucosal tissue that is deep and ill-defined. Acutely urticaria occurs in 20% of the population, whereas chronic urticaria and angioedema occur in 0.5%. Dermographism is evoked by skin stroking; pressure urticaria by application of weight to the skin; vibratory angioedema by a vibratory stimulus; cholinergic urticaria can be diagnosed by exercise to sweating; solar urticaria by testing with UVB, UVA, and visible light; cold urticaria by application of ice cube to skin. Second-line therapies could involve a short course of oral systemic corticosteroids for severe urticaria and urticarial vasculitis. A rare disorder with an incidence between 2.3 and 10 per million population, four times more common in females. A rare disease with an incidence of 1.9 per million, occurring twice as frequently in females as in males.
The Molecular Model and the Cytotoxic Action of UV Light
K. H. Chadwick in Understanding Radiation Biology, 2019
The important role for oxidative damage in the UVA effect implies that pairs of oxidative deoxyribonucleic acid (DNA) single stranded damage form the critical lesion and not pyrimidine dimers. Ultraviolet (UV) light falls between visible light and X-rays and gamma rays on the spectrum of electromagnetic radiation and is strongly associated with skin cancer. The UV range is usually divided up into UVA, UVB and UVC. The review by Cadet et al. reveals a wide range of photoproducts induced in the cell by UVA exposure and also reveals the importance of the oxidative damage, such as DNA single strand breaks and 8-oxo-7,8-dihydroguanine DNA base damage for the biological effect. Some good experimental data supporting the ‘paired dimer’ lesion as critical for UV cellular effects are to be found in the work of Wade and Lohman. They measured UV-induced cell survival in chicken embryo cells before and after photo-reactivation and correlated survival with number of endonuclease-sensitive sites, which are presumed to be dimers.
Squamous cell carcinoma
Robert Baran, Dimitris Rigopoulos in Nail Therapies, 2012
In literature, only 200 cases of squamous cell carcinoma (SCC) have been reported so far; however, this is the most common malignant tumor of the nail unit. Studies suggest that human papillomavirus (HPV) infection (especially, HPV-16 isolated in more than 60% of the cases) is involved in its pathogenesis. Other possible etiologies include iatrogenic or accidental irradiation (radiologists and technicians), chronic infl ammation and chronic solar irradiation (although this factor is less supported since the nail plate blocks all the amount of UVB and allows only a small quantity of UVA to penetrate). Men over 50 are candidate patients, with the thumb and index fi ngers being the most preferred location for the disease. It is rarely found on the toes.
Osmolyte taurine induction in UVA exposed human retinal pigment epithelial cells
Published in Cutaneous and Ocular Toxicology, 2018
Aim: To explore the osmolytes expression in ultraviolet (UVA) stressed human retinal pigment epithelial cells. Methods: Osmolyte transporters and vascular endothelial growth factor (VEGF) messenger RNA (mRNA) were determined by real time polymerase chain reaction (PCR). Osmolyte uptake was measured by radioimmunoassay. VEGF concentrations were determined by immunoassay and enzyme-linked immunosorbent assay (ELISA). Osmolyte taurine transporter (TAUT) were silenced by siRNA technology. Results: Hypertonicity accelerated osmolyte betaine uptake, myoinositol uptake, and taurine uptake, compared to normotonic stress. UVA irradiation also accelerated osmolyte transporters expression and osmolytes uptake. Especially, osmolyte taurine remarkably inhibited VEGF release induced by UVA irradiation. VEGF in the UVA stressed retinal pigment epithelial cell supernatant was accumulated slow after taurine preincubation. VEGF expression increased significantly in UVA-stressed cells after TAUT silencing. Moreover, taurine reduced the VEGF level in human ocular aqueous humor. Conclusion: The inhibition of VEGF by osmolyte taurine plays the crucial role in retina adaption to UVA irradiation.
Isolated Internal Ophthalmoplegia Secondary to Herpes Zoster Ophthalmicus: A Rare Case Report
Published in Neuro-Ophthalmology, 2020
Dilek Top Karti, Dilara Aktert, Nese Celebisoy
Herpes zoster becomes latent in the sensory ganglia after the primary infection and may reactivate many years later to produce shingles in adults. Involvement of the ophthalmic branch of the trigeminal nerve with this virus is called Herpes zoster ophthalmicus (HZO). The eyelid skin, cornea, uvea, retina, optic nerve and other cranial nerves can be affected by HZO. Isolated internal ophthalmoplegia can rarely be seen. Clinicians should be aware of this condition and HZO must be kept in mind in the differential diagnosis of anisocoria.
UVA radiation augments cytotoxic activity of psoralens in melanoma cells
Published in International Journal of Radiation Biology, 2017
Dorota Wrześniok, Artur Beberok, Jakub Rok, Marcin Delijewski, Anna Hechmann, Martyna Oprzondek, Zuzanna Rzepka, Barbara Bacler-Żbikowska, Ewa Buszman
Purpose: Melanoma is an aggressive form of skin cancer. The aim of the study was to evaluate the influence of UVA radiation and psoralens: 5-methoxypsoralen (5-MOP) or 8-methoxypsoralen (8-MOP) on melanoma cells viability. Materials and methods: The amelanotic C32 and melanotic COLO829 human melanoma cell lines were exposed to increasing concentrations of psoralens (0.1–100 μM) in the presence or absence of UVA radiation. Cell viability was evaluated by the WST-1 assay. Results: We demonstrated that 8-MOP, in contrast to 5-MOP, has no cytotoxic effect on both melanoma cell lines. Simultaneous exposure of cells to 8-MOP and UVA radiation caused significant cytotoxic response in C32 cells where the EC50 value was estimated to be 131.0 μM (UVA dose: 1.3 J/cm2) and 105.3 μM (UVA dose: 2.6 J/cm2). The cytotoxicity of 5-MOP on both C32 and COLO829 cells was significantly augmented by UVA radiation – the EC50 was estimated to be 22.7 or 7.9 μM (UVA dose: 1.3 J/cm2) and 24.2 or 7.0 μM (UVA dose: 2.6 J/cm2), respectively. Conclusions: The demonstrated high cytotoxic response after simultaneous exposure of melanoma cells to psoralens and UVA radiation in vitro suggests the usefulness of PUVA therapy to treat melanoma in vivo.