Many chameleons, and panther chameleons in particular, have the remarkable ability to exhibit complex and rapid colour changes during social interactions such as male contests or courtship. It is generally interpreted that these changes are due to dispersion/aggregation of pigment-containing organelles within dermal chromatophores. Here, combining microscopy, photometric videography and photonic band-gap modelling, we show that chameleons shift colour through active tuning of a lattice of guanine nanocrystals within a superficial thick layer of dermal iridophores. In addition, we show that a deeper population of iridophores with larger crystals reflects a substantial proportion of sunlight especially in the near-infrared range. The organization of iridophores into two superposed layers constitutes an evolutionary novelty for chameleons, which allows some species to combine efficient camouflage with spectacular display, while potentially providing passive thermal protection.

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Photonic crystals cause active colour change in chameleons

A significant advantage of Raman spectroscopy as a noninvasive optical technique is its ability to detect subtle molecular or biochemical signatures within tissue. One of the major challenges for biomedical Raman spectroscopy is the removal of intrinsic autofluorescence background signals, which are usually a few orders of magnitude stronger than those arising from Raman scattering. A number of methods have been proposed for fluorescence background removal including excitation wavelength shifting, Fourier transformation, time gating, and simple or modified polynomial fitting. The single polynomial and the modified multi-polynomial fitting methods are relatively simple and effective, and thus are widely used in biological applications. However, their performance in real-time in vivo applications and low signal-to-noise ratio environments is sub-optimal. An improved automated algorithm for fluorescence removal has been developed based on modified multi-polynomial fitting, but with the addition of (1) a peak-removal procedure during the first iteration, and (2) a statistical method to account for signal noise effects. Experimental results demonstrate that this approach improves the automated rejection of the fluorescence background during real-time Raman spectroscopy and for in vivo measurements characterized by low signal-to-noise ratios.

Automated Autofluorescence Background Subtraction Algorithm for Biomedical Raman Spectroscopy

Vitiligo is an acquired pigmentary disorder of unknown etiology that is clinically characterized by the development of white macules related to the selective loss of melanocytes. The prevalence of the disease is around 1% in the United States and in Europe, but ranges from less than 0.1% to greater than 8% worldwide. A recorded predominance of women may reflect their greater willingness to express concern about cosmetically relevant issues. Half of all patients develop the disease before 20 years of age. Onset at an advanced age occurs but is unusual, and should raise concerns about associated diseases, such as thyroid dysfunction, rheumatoid arthritis, diabetes mellitus, and alopecia areata. Generalized vitiligo is the most common clinical presentation and often involves the face and acral regions. The course of the disease is unpredictable and the response to treatment varies. Depigmentation may be the source of severe psychological distress, diminished quality of life, and increased risk of psychiatric morbidity. Part I of this two-part series describes the clinical presentation, histopathologic findings, and various hypotheses for the pathogenesis of vitiligo based on past and current research.

https://www.jaad.org/article/S0190-9622(11)00039-9/pdf

Vitiligo: A comprehensive overview: Part I. Introduction, epidemiology, quality of life, diagnosis, differential diagnosis, associations, histopathology, etiology, and work-up

Objective: Our objective was to develop clinical practice guidelines for the evaluation and treatment of hirsutism in premenopausal women. Participants: The Task Force was composed of a chair, selected by the Clinical Guidelines Subcommittee (CGS) of The Endocrine Society, six additional experts, two methodologists, and a medical writer. The Task Force received no corporate funding or remuneration. Evidence: Systematic reviews of available evidence were used to formulate the key treatment and prevention recommendations. We used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) group criteria to describe both the quality of evidence and the strength of recommendations. We used “recommend” for strong recommendations, and “suggest” for weak recommendations. Consensus Process: Consensus was guided by systematic reviews of evidence and discussions during one group meeting, several conference calls, and e-mail communications. The drafts prepared by the Task Force with the help of a...

https://endosuem.org.uy/wp-content/uploads/2015/05/Hirsutismo.-Endocrine-Society-2008.pdf

Evaluation and Treatment of Hirsutism in Premenopausal Women: An Endocrine Society Clinical Practice Guideline

Vitiligo is a depigmenting disorder characterized by the development of white patches in various distributions, which are due to the loss of melanocytes from the epidermis. A variety of arguments from clinical observations to research findings in human and animal models support the hypothesis of autoimmunity and are reviewed in this article. The association with autoimmune diseases and organ-specific autoantibodies is well known. Various effective treatment options have an immunosuppressive effect. Today the autoimmune pathogenesis of the disease has become a rapidly evolving field of research. Detection of circulating melanocyte antibodies in human and animal models implicates a possible role of humoral immunity. Histological and immunohistochemical studies in perilesional skin suggest the involvement of cellular immunity in vitiligo. Recently, T-cell analyses in peripheral blood further support this hypothesis. Interestingly, new insights in the association of vitiligo and melanoma may help to clarify the role of autoimmunity in the development of vitiligo.

https://onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0749.2003.00023.x

Evidence for an Autoimmune Pathogenesis of Vitiligo

We successfully acquire the in vivo Raman spectrum of melanin from human skin using a rapid near-infrared (NIR) Raman spectrometer. The Raman signals of in vivo cutaneous melanin are similar to those observed from natural and synthetic eumelanins. The melanin Raman spectrum is dominated by two intense and broad peaks at about 1580 and 1380 cm ˛1 , which can be interpreted as originating from the in-plane stretching of the aromatic rings and the linear stretching of the C-C bonds within the rings, along with some contributions from the C-H vibrations in the methyl and methylene groups. Variations in the peak frequencies and bandwidths of these two Raman signals due to differing biological environments have been observed in melanin from different sources. The ability to ac- quire these unique in vivo melanin signals suggests that Raman spec- troscopy may be a useful clinical method for noninvasive in situ analysis and diagnosis of the skin. © 2004 Society of Photo-Optical Instrumenta-

https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-9/issue-06/0000/Raman-spectroscopy-of-in-vivo-cutaneous-melanin/10.1117/1.1805553.pdf

Raman spectroscopy of in vivo cutaneous melanin.

Objective Hair removal using lasers or broadband intense pulsed light has become one of the most ubiquitous medical procedures. At our center a small proportion of patients have spontaneously reported what they believed to be increased hair growth at sites of previous laser epilation. We sought to retrospectively review the prevalence and features of this paradoxical effect. Methods This was a single center, retrospective study that included all patients who underwent laser hair removal during a 4-year period with a long-pulsed alexandrite laser. All cases of laser-induced hypertrichosis were assessed clinically by history, examination, and laboratory tests, and confirmed by review of serial clinical photographs taken during the course of the laser treatments. The clinical features of patients with postlaser hypertrichosis were compared with 50 patients randomly selected from among all those who had undergone laser hair removal at our center (n=489). Results Of 489 patients, 3 (0.6%, 95% confidence interval: 0.01-1.9%) treated with the long-pulsed alexandrite laser (755 nm) reported increased hair after laser hair epilation. There was a trend for this adverse effect to occur in darker skin phototypes (IV) and with black hair as compared with the unaffected comparison group (n=50). However, the small number of cases (n=3) did not provide sufficient power to adequately test factors such as age, sex, treatment settings, and number of treatments statistically. Conclusion Postlaser hair removal hypertrichosis is a real but rare occurrence in our experience.

https://www.jaad.org/article/S0190-9622(05)00722-X/pdf

Paradoxical hypertrichosis after laser epilation.

Adoptive transfer of donor immunity has been demonstrated in animals after bone marrow transplantation (BMT). In humans, several autoimmune diseases have been similarly transferred. Although BMT may, per se, be associated with a modulation of the recipient's immune system, which could trigger or even cause autoimmune diseases, both animal experiments and experience with humans show the likeliness of adoptive transfer of donor immunity to the recipient. We describe a patient with multiple myeloma in whom generalized vitiligo developed within 3 months after allogeneic BMT from his HLA-matched sister with vitiligo. We believe that a form of adoptive transfer of donor immunity to the recipient might play a role in the development of vitiligo. In spite of this, neither de novo development of vitiligo in a genetically predisposed patient nor autoimmune phenomena associated with graft-versus-host disease can be completely excluded as a contributing factor for development of vitiligo in our patient. To our knowledge, this is the first case report of transfer of vitiligo after BMT from a donor with vitiligo.

https://www.jaad.org/article/S0190-9622(02)77332-5/pdf

Transfer of vitiligo after allogeneic bone marrow transplantation

A total of 27 T-lymphocyte cell strains were established from skin biopsies of 24 patients with various stages of cutaneous T-cell lymphoma (CTCL) by addition of the T-cell growth factors interleukin (IL)-2 and IL-4. Cellular proliferation and phenotypic changes were measured over 3 months in culture, and T-cell clones were studied using T-cell receptor-? re-arrangement techniques. An average outgrowth of 134 million T-lymphocytes from a 4-mm skin biopsy was observed over 2 months. Initially, most T-cells expressed the CD4+ phenotype. In 17 cell strains from patients with early CTCL a statistically significant predominance of CD8+ T-lymphocytes developed over 8-weeks' culture, indicating that CD8+ T-cells controlled the growth of CD4+ T cells, whereas CD4+ T-cells were predominant in cell strains from advanced CTCL (p <0.05). TCR-? re-arrangement studies revealed, on average, 12 T-cell clones per cell strain, which was reduced over time to 6 T-cell clones per cell strain. Lymphocytes from peripheral blood could kill lymphocytes from an autologous cell strain, suggesting the presence of autoreactive cytotoxic T-cells. Our study suggests how skin-homing CD8+ T-lymphocytes from patients with early stage CTCL can suppress the in vitro growth of skin-homing CD4+ T-lymphocytes, indicating immune surveillance.

Skin-homing CD8+ T lymphocytes show preferential growth in vitro and suppress CD4+ T-cell proliferation in patients with early stages of cutaneous T-cell lymphoma.

ABSTRACT Nail psoriasis causes significant aesthetic and functional disabilities. The treatment of nail psoriasis is essential to improve the health outcomes and quality of life among patients. Pain associated with intralesional injections, inadequate penetration into the nail and underlying tissue, poor adherence to therapy, limited efficacy and recurrent relapses are among the many challenging issues with topical therapy. While conventional systemic therapies are still useful and often appropriate for some patients, current evidence indicates that highly selective agents including anti-tumor necrosis factor-alpha, anti-interleukin (IL)-17 and anti-IL-12/23 antibodies that are primarily available for plaque psoriasis and psoriatic arthritis have also demonstrated long-term efficacy in the treatment of nail psoriasis. We report a case of nail psoriasis improved with treatment by risankizumab.

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Abdulmajeed Alajlan

Papers

Raman spectroscopy of in vivo cutaneous melanin.

Paradoxical hypertrichosis after laser epilation.

Transfer of vitiligo after allogeneic bone marrow transplantation

Skin-homing CD8+ T lymphocytes show preferential growth in vitro and suppress CD4+ T-cell proliferation in patients with early stages of cutaneous T-cell lymphoma.

A case of nail psoriasis improved with treatment by risankizumab