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Abstract Introduction Chylolymphatic mesenteric cysts are rare entities with variable presentations and this has surgical implications in the pediatric age group. Case presentation We carried out a retrospective analysis of the clinical and histopathological records of pediatric patients diagnosed and treated for chylolymphatic mesenteric cysts at our institute from 1998 to 2008. Eight patients met the histopathological criteria of chylolymphatic mesenteric cyst. These patients were in the age range 18 months to 10 years with a mean age of 4.5 years. Of these eight patients, four presented with an abdominal lump, and two each with abdominal pain and acute intestinal obstruction. On clinical examination, five out of the eight patients had a palpable abdominal mass. Laparotomy and complete excision of the cyst along with the involved gut was performed in all patients. There were no postoperative complications or any recurrence during the follow-up period which ranged from 4 months to 8 years. Conclusion Although very rare, chylolymphatic mesenteric cyst should be kept in mind as one of the differential diagnoses of cystic masses of the abdomen including cystic lymphangioma. Ultrasonography and computed tomography suggest the diagnosis but histopathological examination is required for confirmation. Complete excision of the cyst yields excellent results.

Hydroxychloroquine is a disease-modifying antirheumatic drug used for various rheumatological conditions. Its long-term use is well-known to have toxic effects on cardiac muscle cells. We present a biopsy-proven case of hydroxychloroquine-induced cardiotoxicity with detailed histopathological and imaging findings. The patient was referred to our heart failure clinic for concerns of reduction in left ventricular ejection fraction despite being on guideline-directed medical therapy. She had been diagnosed with rheumatoid arthritis, pulmonary hypertension and then subsequently heart failure with reduced ejection fraction 5 years ago. The evaluation included right heart catheterisation, cardiac MRI and endomyocardial biopsy. Light and electron microscopy showed myocyte hypertrophy and vacuolar change, abnormal mitochondria, myeloid bodies and curvilinear bodies. These findings were specific for hydroxychloroquine-induced cardiomyopathy. This case highlights the importance of clinical monitoring, early suspicion and consideration of drug-induced toxicities as a culprit for heart failure., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Lutein and zeaxanthin are xanthophyll carotenoids with potent antioxidant properties protecting the skin from acute photodamage. This study extended the investigation to chronic photodamage and photocarcinogenesis. Mice received either a lutein/zeaxanthin-supplemented diet or a standard nonsupplemented diet. Dorsal skin of female Skh-1 hairless mice was exposed to UVB radiation with a cumulative dose of 16,000 mJ/cm(2) for photoaging and 30,200 mJ/cm(2) for photocarcinogenesis. Clinical evaluations were performed weekly, and the animals were sacrificed 24 h after the last UVB exposure. For photoaging experiments, skin fold thickness, suprapapillary plate thickness, mast cell counts and dermal desmosine content were evaluated. For photocarcinogenesis, samples of tumors larger than 2 mm were analyzed for histological characterization, hyperproliferation index, tumor multiplicity, total tumor volume and tumor-free survival time. Results of the photoaging experiment revealed that skin fold thickness and number of infiltrating mast cells following UVB irradiation were significantly less in lutein/zeaxanthin-treated mice when compared to irradiated animals fed the standard diet. The results of the photocarcinogenesis experiment were increased tumor-free survival time, reduced tumor multiplicity and total tumor volume in lutein/zeaxanthin-treated mice in comparison with control irradiated animals fed the standard diet. These data demonstrate that dietary lutein/zeaxanthin supplementation protects the skin against UVB-induced photoaging and photocarcinogenesis., ((c) 2007 S. Karger AG, Basel.)

Background: UV radiation induces damage to human skin. Protection of skin by an oral photoprotective agent would have substantial benefits. Objective We investigated the photoprotective effect of oral administration of an extract of the natural antioxidant Polypodium leucotomos (PL)., Methods: A total of 9 healthy participants of skin types II to III were exposed to varying doses of artificial UV radiation without and after oral administration of PL (7.5 mg/kg). At 24 hours after exposure the erythema reaction was assessed and paired biopsy specimens were obtained from PL-treated and untreated skin., Results: A significant decrease in erythema was found in PL-treated skin (P < .01). Histologically, PL-treated biopsy specimens showed less sunburn cells (P < .05), cyclobutane pyrimidine dimers (P < .001), proliferating epidermal cells (P < .001), and dermal mast cell infiltration (P < .05). A trend toward Langerhans cell preservation was seen., Conclusion: Oral administration of PL is an effective systemic chemophotoprotective agent leading to significant protection of skin against UV radiation.

Background: The use of psoralen-UVA (PUVA) in patients of skin phototype I to II is limited by side effects of acute phototoxicity and possible long-term carcinogenesis., Objective: We sought to assess oral Polypodium leucotomos (PL) extract in decreasing PUVA-induced phototoxicity of human skin on a clinical and histologic level., Methods: A total of 10 healthy patients with skin phototypes II to III were exposed to PUVA alone (using 0.6 mg/kg oral 8-methoxypsoralen) and to PUVA with 7.5 mg/kg of oral PL., Results: Clinically, phototoxicity was always lower in PL-treated skin after 48 to 72 hours (P<.005), and pigmentation was also reduced 4 months later. Histologically, PL-treated skin showed a significant numeric reduction of sunburn cells (P=.05), preservation of Langerhans cells (P< or =.01), decrease of tryptase-positive mast cell infiltration (P<.05), and decrease of vasodilation (P< or =.01). No differences were found in Ki-67+ proliferating cells., Conclusions: PL is an effective chemophotoprotector against PUVA-induced skin phototoxicity and leads to substantial benefits of skin protection against damaging effects of PUVA as evidenced by histology.

Lutein and zeaxanthin are carotenoids found in green leafy vegetables with interesting antioxidant properties. They are present in high concentrations in the fovea centralis of the human retina and their role in the prevention of age-related macula degeneration has been reported. We have investigated the effect of orally administered lutein and zeaxanthin in the cutaneous response to ultraviolet B irradiation. Female hairless SKh-1 mice receiving 0.4% and 0.04% lutein plus zeaxanthin-enriched diet for 2 wk were exposed to single doses of ultraviolet B radiation. Skin biopsies were taken at 24 and 48 h after irradiation and analyzed for the presence of apoptotic cells, proliferating cells, and expression of proliferating cell nuclear antigen. Our results show a clear ultraviolet-induced dose-dependent inflammatory response. Orally administered 0.4% lutein and zeaxanthin decreased significantly the edematous cutaneous response (p<0.01) as determined by the reduction of the UVB-induced increase of ear bifold thickening. Additionally, dietary carotenoids were efficient in reducing the ultraviolet B-induced increases in the percentage of proliferating cell nuclear antigen (p<0.05), bromodeoxyuridine (p<0.05), and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling-positive cells (p<0.01). These data demonstrate that oral supplementation of lutein and zeaxanthin diminishes the effects of ultraviolet B irradiation by reducing acute inflammatory responses and ultraviolet-induced hyperproliferative rebound.

Chronic ultraviolet B (UVB) exposure of human or murine skin is known to induce cutaneous photoaging and enhanced carcinogenic risk. An extract of Polypodium leucotomos (PL), a tropical fern plant, has been known to exhibit interesting antioxidant and photoprotective properties against acute exposure to ultraviolet radiation. The objective of this preliminary (or pilot) study was to determine the photoprotective role of topically applied Polypodium leucotomos extract in the prevention or amelioration of cutaneous changes of photoaging in hairless mice. PL-treated mice showed significant reduction of skinfold thickness than those observed in PL-untreated controls. Additionally, PL-treated mice showed a significantly lower degree of histologic parameters of photoaging damage, including dermal elastosis, compared with positive control mice. Interestingly, PL treatment also showed reduction in the number of mice showing skin tumors at 8 weeks after the cessation of the UVB exposure protocol. The results of this preliminary study illustrate that PL treatment helped to ameliorate and to partially inhibit some of the histologic damage associated with photoaging of skin and appeared to contribute to a decrease in the prevalence of UVB-induced skin tumors in mice.

Sunburn, immune suppression, photoaging, and skin cancers result from uncontrolled overexposure of human skin to solar ultraviolet radiation (UVR). Preventive measures, including photoprotection, are helpful and can be achieved by topical sunscreening agents. Polypodium leucotomos (PL) has been used for the treatment of inflammatory diseases and has shown some in vitro and in vivo inmunomodulating properties. Its beneficial photoprotective effects in the treatment of vitiligo and its antioxidant properties encouraged us to evaluate in vivo the potentially useful photoprotective property of natural extract of PL after topical application or oral ingestion. Twenty-one healthy volunteers [either untreated or treated with oral psoralens (8-MOP or 5-MOP)] were enrolled in this study and exposed to solar radiation for evaluation of the following clinical parameters: immediate pigment darkening (IPD), minimal erythema dose (MED), minimal melanogenic dose (MMD), and minimal phototoxic dose (MPD) before and after topical or oral administration of PL. Immunohistochemical assessment of CD1a-expressing epidermal cells were also performed. PL was found to be photoprotective after topical application as well as oral administration. PL increased UV dose required for IPD (P < 0.01), MED (P < 0.001) and MPD (P < 0.001). After oral administration of PL, MED increased 2.8 +/- 0.59 times and MPD increased 2.75 +/- 0.5 and 6.8 +/- 1.3 times depending upon the type of psoralen used. Immunohistochemical study revealed photoprotection of Langherhans cells by oral as well as topical PL. The observed photoprotective activities of oral or topical PL reveal a new avenue in examining the potentially useful field of systemic photoprotection and suggests that PL can be used as adjunct treatment and can make photochemotherapy and phototherapy possibly safe and effective when the control of cutaneous phototoxicity to PUVA or UVB is a limiting factor in such phototherapies.

The acute reactions of human skin to solar ultraviolet radiation (290-400 nm) are recognized as a form of inflammation reactions that are mediated by several possible mechanisms including (a) direct action of photons on DNA, (b) generation of reactive free radicals and reactive oxygen species involving the formation of O2.-, 1O2, H2O2, OH, etc., (c) generation of prostaglandins (PGD2, PGE2, etc.), histamine, leucotrienes, and other inflammatory mediators. It is conceivable that UV-induced reactions represent oxidative stress mediated by the formation of free radicals, reactive oxygen, lipid peroxidation, liberation of membrane phospholipids, and subsequent formation of prostaglandins by cyclo-oxygenase pathway. In this study, we examined the role of reactive oxygen species and lipid peroxidation in in vitro reactions as well as in vivo skin inflammation reactions induced by (a) UVB radiation (290-320 nm), and (b) skin photosensitization reaction by PUVA treatment involving 8-methoxypsoralen and UVA (320-400 nm) radiation and presented data for the generation of superoxide anion O2.-) and lipid peroxides. We have also evaluated, both in vitro as well as in vivo systems, the quenching or the inhibition of O2.- by a plant extract known as Polypodium leucotomos. The P. leucotomos extract was found to exhibit interesting antioxidant and anti-inflammatory as well as photoprotective properties against photo-oxidative stress involving the generation of reactive oxygen, lipid peroxidation under in vitro reactions as well as in vivo experimental conditions. Significant inhibition of UVB-induced erythemal response, and 8-methoxypsoralen plus UVA-induced phototoxic reaction after topical application or oral administration of the photosensitizer could be demonstrated in guinea pig skin and human skin following the topical application of P. leucotomos extract. The photoprotective mechanism of P.leucotomos involving interaction with reactive oxygen species or free radicals appears to have potential clinical usefulness in preventing sunburn and inhibiting phototoxic reaction.

3-Carbethoxypsoralen (3-CP), a linear tricyclic psoralen, known for its photoreaction with DNA to form monofunctional cyclobutane adducts with pyrimidine bases, was found to produce a highly reactive cytotoxic species, singlet oxygen (1O2) to a greater extent than several other linear psoralens such as psoralen, 8-MOP, 5-MOP or angular psoralens (angelicin). 3-CP also produced superoxide radicals (O2-.) at a rate slower than psoralens in the following order:psoralen > angelicin > 3-CP > 8-MOP > 5-MOP. 1O2 produced by photoactivated 3-CP was found to oxidize tyrosine and Dopa to Dopachrome, and subsequently their conversion to melanin. It also induced photooxidation of 2'-deoxyguanosine. Reactive oxygen species produced by 3-CP also induced lipid peroxidation. The rate of dopachrome formation to promote its conversion to melanin and lipid peroxidation by 3-CP and other linear and angular psoralens and hematoporphyrin derivatives may be related to their skin photosensitizing ability and the rate of 1O2 production. Topically applied 3-CP on hairless mice exposed to UVA radiation was found to be a nonphotocarcinogenic agent in contrast to 8-MOP, which under similar conditions produced a 70% tumour yield (squamous cell carcinoma) in 65 weeks. 3-CP was observed to be a photolabile compound and was converted to a dihydro-form as previously reported by other investigators. The photoconversion of 3-CP to 4',5'-dihydro-3-CP was enhanced under N2, whereas, under O2 atmosphere, lesser degree of photoconversion was observed, thus, indicating that reduction takes place via an anoxic or Type I mechanism. The significance of these observations are discussed in relation to the skin photosensitizing, nonphotocarcinogenic, and photochemotherapeutic potential of 3-CP.

Four new benzo- and tetrahydrobenzo-psoralens have been examined in their reversible interaction toward DNA and in their DNA-photobinding properties. These compounds were also examined for their ability to produce singlet oxygen and in vivo skin photosensitization reaction. Fluorescence and equilibrium dialysis measurements show that the complexation ability of benzoderivatives is remarkably high. Binding is less effective in the case of the tetrahydrocongeners. All compounds photoreact quite effectively to DNA. The photoadducts were obtained by enzymatic hydrolysis of drug-modified DNA and were characterized by high performance liquid chromatographic elution techniques. The 3,4 position represents the unique photoreactive site for benzopsoralens. Denaturation-renaturation experiments confirm that the benzoderivatives are purely monofunctional, while the tetrahydrocongeners form interstrand cross-links, even though to a remarkably lesser extent than 8-methoxypsoralen (8-MOP). The new compounds, in the presence of long-wavelength ultraviolet radiation, are very moderately effective in forming reactive oxygen species; they are ineffective in promoting oxidation of tyrosine and 3-(3,4-dihydroxyphenyl)alanine to dopachrome and melanin. Skin photosensitizing experiments on guinea pigs indicate that benzo- and tetrahydrobenzopsoralen derivatives are almost devoid of any phototoxic effects. Thus, this class of compounds appears to be interesting for the development of new, less phototoxic chemotherapeutic agents that interact with DNA better than 8-MOP.

In this paper, the role of reactive oxygen species in photoaging is presented. Many photosensitizing agents are known to generate reactive oxygen species (singlet oxygen (1O2), superoxide anion (O2.-) and .OH radicals). Although photoaging (dermatoheliosis) of human skin is caused by UVB and UVA radiation, the hypothesis tested here in the pathogenesis of photoaging of human skin is the free radical theory involving the generation of reactive oxygen species by UVA (320-400 nm) radiation and their damaging oxidative effects on cutaneous collagen and other model proteins. The UVA-generated reactive oxygen species cause cross-linking of proteins (e.g. collagen), oxidation of sulfydryl groups causing disulfide cross-links, oxidative inactivation of certain enzymes causing functional impairment of cells (fibroblasts, keratinocytes, melanocytes, Langerhans cells) and liberation of proteases, collagenase and elastase. The skin-damaging effects of UVA appear to result from type II, oxygen-mediated photodynamic reactions in which UVA or near-UV radiation in the presence of certain photosensitizing chromophores (e.g., riboflavin, porphyrins, nicotinamide adenine dinucleotide phosphate (NADPH), etc.) leads to the formation of reactive oxygen species (1O2, O2.-, .OH). Four specific observations are presented to illustrate the concept: (1) the production of 1O2 and O2.- by UVB, UVA and UVA plus photosensitizing agents (such as riboflavin, porphyrin and 3-carbethoxypsoralens) as a function of UV exposure dose, the sensitizer concentration and the pH of the irradiated solution; (2) the formation of protein cross-links in collagen, catalase and superoxide dismutase by 1O2 and O2.- (.OH) and the resulting denaturation of proteins and enzyme activities as a function of UVA exposure dose; (3) the protective role of selective quenchers of 1O2 and O2.- (e.g. alpha-tocopherol acetate, beta-carotene, sodium azide, ascorbic acid, etc.) against the photoinactivation of enzymes and the prevention of the protein cross-linking reaction; (4) the possible usefulness of certain antioxidants or quenchers that interact with the UVA-induced generation of reactive oxygen species in the amelioration of the process of photoaging.

The therapeutic uses of naturally occurring psoralens in modern-day medicine (8-methoxypsoralen (8-MOP), 5-methoxypsoralen (5-MOP), 4,5',8-trimethylpsoralen, and a few other synthetic psoralens) have evolved through five stages of development. (1) In the historical period (2000 BC to 1930 AD), the pigment-stimulating properties of naturally occurring plants containing psoralens were described anecdotally. (2) The second period (1930-1960) dealing with the chemistry of psoralens involved extraction, identification of their structure, synthesis, and the relationship between chemical structure and their photoreactivity and pigment-stimulating properties. The treatment of vitiligo with oral and topical 8-MOP became popular. (3) In the third period (1960-1974), we witnessed a new beginning and the growth of basic science studies and clinical investigations into various biological properties of psoralens including action spectrum studies, mutagenesis and carcinogenesis studies, in vitro and in vivo photoreactivity studies of various psoralens with DNA, RNA, proteins, and pharmacological and toxicological studies in vitiligo patients undergoing long-term therapy for repigmentation. (4) The fourth period (1974-1988) is recognized as the period of photochemotherapy and the development of the science of photomedicine which established the therapeutic effectiveness of psoralens in combination with newly developed UV irradiation systems that emitted high-intensity UVA radiation in the treatment of severe psoriasis, mycosis fungoides, and over 16 other skin diseases. The effectiveness of PUVA (psoralen + UVA) was confirmed by well controlled clinical trials in thousands of patients, both in the USA and in European countries. Combination therapy with oral retinoids and PUVA contributed to greater effectiveness and long-term safety of psoralen photochemotherapy. (5) In the fifth period (1989 and beyond), psoralens are now emerging as photochemoprotective agents against non-melanoma skin cancers and as immunologic modifiers in the management of certain patients with disorders of circulating T-cells using new techniques of photopheresis. In the final analysis, perhaps the application of pharmacological and therapeutic concepts and principles of using psoralens in combination with UVA has contributed to the development of a new science of photomedicine in which the interaction between basic scientists, photobiologists, and physicians has produced both basic and new clinical knowledge for the care and control of human suffering.

We examined the role of UVR (UV radiation) (UVA, 320-400 nm; UVB, 290-320 nm; and the combination of UVA and UVB) as a promoter in the induction of cutaneous melanoma. One hundred and seventy hairless mice (Skh-hr2), 6-8 weeks old, were treated in 8 groups: group I, DMBA [7,12-dimethylbenz(a)anthracene] plus UVA; group II, DMBA plus UVA plus UVB; group III, DMBA plus UVB; group IV, DMBA; group V, UVA; group VI, UVA plus UVB; group VII, UVB; group VIII, control. DMBA (0.5% solution) was applied once to promote the formation of dermal melanocytic nevus-like lesions while UVR treatments were conducted 3 times/week for 30 weeks. The mice were examined periodically for the development of multiple pigmented lesions, papillomas, squamous cell carcinomas, melanomas, and lymphomas. Treatment with DMBA plus UVA, DMBA plus UVB, and DMBA plus UVA plus UVB stimulated the development of multiple pigmented nevus-like lesions (85-100%) in mice of groups I, II, III, and IV. Upon necroscopy, 27-33% of animals in groups I, II, and III receiving UVR treatments developed clinically and histologically characterized melanomas. Treatment with DMBA alone did not produce melanomas. DMBA-treated animals in groups I, II, and III which received UVR treatments also developed lymphomas (21-50%). Animals treated with DMBA alone or those that received UVB or the combination of UVB plus UVA (without DMBA) developed only papillomas and squamous cell carcinomas (25-47%). Skin tumors were analyzed for the presence of point mutations in the ras gene. Polymerase chain reaction amplification of DNA and selective oligonucleotide hybridization revealed mutations in the 61st codon of the N-ras gene in the precursor nevus-like lesions and melanoma samples studied. This study suggests that UVR (both UVA and UVB) plays a role as a promoter in the stimulation of melanoma and lymphoma development in hairless mice.

Clinical and experimental evidence explaining and supporting the role of UV radiation as a causal factor for the induction and promotion of nonmelanoma and malignant melanoma skin cancer are presented. While there is excellent animal experimental data and human epidemiologic evidence supporting the causal relationship of UVR (UVB, as well as UVA radiation) for basal and squamous cell carcinomas, the data establishing a direct causal relationship between melanoma and exposure to sunlight appear to be complex. They do, however, suggest a definite promotional role of sunlight in the causation of melanoma. Using a hairless pigmented mouse strain (Skh-hr2), experiments were initiated to examine the role of UVR in the induction of melanoma. A single application of DMBA as an initiator and subsequent thrice-weekly exposures to either UVB (290-320 nm) or UVA (320-400 nm) or the combined exposures of UVA and UVB resulted in the formation of blue nevus-like lesions. Repeated UVR exposures for over 30 weeks resulted in the development of melanoma (38%), as well as lymphoma and squamous cell carcinoma only in those mice that were pretreated with DMBA and had developed nevi. Mice receiving UVB, UVA, or the combination treatments of UVB plus UVA without DMBA pretreatment developed papillomas and squamous cell carcinoma but no melanoma. These studies indicate that some initiation event is essential to transform melanocytes to blue nevus-like lesions before UVR (UVB + UVA) can act as a promoter and accelerate the development of malignant melanoma, as as well as lymphoma.

Crude coal tar (CCT) and certain photoreactive ingredients of CCT are photosensitizing agents used in the treatment of skin diseases (psoriasis, atopic eczema, etc.). Limited information is available in elucidating the mode of action of CCT in clearing psoriasis or causing skin photosensitization reactions. The production of singlet oxygen (1O2) and superoxide radicals (O(2) or HO2), the formation of interstrand cross-links (ICL) in DNA, and the skin photosensitization reaction caused by CCT or the ingredients present in tar preparations have been examined. Both type I (oxygen-independent) and type II (sensitized reactions requiring molecular oxygen) reactions are induced by CCT. Our data show that CCT and some of the photoreactive ingredients present in CCT produce 1O2, O(2), and ICL in DNA upon exposure to UVA radiation. Based on the equivalent concentration, the efficiency of various agents to produce 1O2 was of the following order: hematoporphyrin greater than phenanthridine greater than acridine greater than methylene blue greater than CCT greater than fluoranthrene greater than anthracene greater than pyrene greater than 8-methoxypsoralen greater than anthralin greater than chloroquine greater than anthralin dimer. The O(2) formation with CCT and its ingredients was also of the same order except for anthracene which was found to be a strong producer of O(2). The therapeutic effectiveness of CCT appears to be due to: (a) its cytotoxic effects, and (b) the production of 1O2, O(2), and ICL by CCT and its photoreactive ingredients. The skin photosensitizing (smarting, edema, and erythema responses) and carcinogenic properties of CCT may also be related to the production of 1O2 and O(2) and the formation of ICL which appear to be responsible for inducing the damage to the DNA and cell membrane.

Photosensitization reactions involve phototoxic reactions and photoallergic reactions, which are less common. Common drugs and chemicals that photosensitize humans are listed. Phototoxic reactions include the following: 1) direct photosensitization (type I reactions), in which the reactions of the triplet-state sensitizer are directly attributable to a component other than oxygen (e.g., DNA, proteins, and cell membranes), and 2) indirect photosensitization (type II reactions), in which the triplet state of a sensitizer reacts first with molecular oxygen, producing an "active oxygen" intermediate that subsequently reacts with the biologic system. The active oxygen intermediates are singlet oxygen (1O2)k, superoxide radical anions (O(2), and hydroxy radicals. Psoralen-induced skin photosensitization appears to involve both type I and type II reactions. The formation of monofunctional bifunctional psoralen-DNA photoadducts (a type I reaction) is probably responsible for cell damage, cell death, mutation, and even skin carcinogenesis. The erythema response appears to be the result of a type II reaction.

Photobinding to DNA and cross-linking formation in vitro, as well as the skin photosensitizing activity on guinea pigs of two water-soluble derivatives of psoralen (5 and 8-diethylaminopropyloxypsoralen hydrochloride) have been studied. For purposes of comparison, the results have been correlated with those obtained, in the same experimental conditions, with 5- and 8-methoxypsoralen. The water-soluble 8-derivative showed an increased photoaddition to DNA and cross-linking formation, when compared with 8-methoxy-derivative; on the contrary, the water-soluble 5-derivative was less photoreactive than the corresponding 5-methoxy-derivative. The skin photosensitizing potency of 8-diethylaminopropyloxypsoralen (the more interesting of the two compounds) appears weaker than that of 8-methoxypsoralen after topical application, but higher after oral ingestion or subcutaneous injection.

The basic aspects of cutaneous photosensitization reactions and the mode of therapeutic effectiveness of psoralens and coal tar, the two groups of photosensitizing agents used extensively in the photochemotherapy of psoriasis, have been reviewed. Psoralen-induced skin photosensitization and the therapeutic action of psoralens involve two distinct types of reactions, and these two reactions occur independently of each other and concurrently when the psoralen-treated skin (oral or topical) is exposed to 320 to 400 nm of radiation. The first, type I, is an oxygen-independent reaction and primarily involves photoreaction with DNA; the second, type II, is a sensitized reaction dependent on oxygen and involves the formation of singlet oxygen ((1)O(2)). The photoreactive form of psoralen is its triplet state, and the sites of reaction are (1) the cell membrane of the epidermal, dermal, and endothelial cells; (2) the cytoplasmic constituents, such as enzymes, RNA, lysosomes, etc.; (3) the cell nuclei (DNA and chromatin); and (4) the sensitized production of (1)O(2), which is responsible for cell-membrane damage and vasodilation. The major damage would be initiated by a type I reaction and would be seen in the form of nuclear damage to DNA resulting from the interaction of psoralen with DNA and to a lesser extent with RNA. The skin photosensitization response (erythema, edema, membrane damage, etc.) would result from a type II reaction involving the generation of (l)0(2). Crude coal tar (CCT), widely used in the Goeckerman therapy for psoriasis, also produces type I and type II reactions. The therapeutic and photosensitizing actions of CCT are due to (1) the photoconjugation of the photoreactive ingredients of CCT with DNA, causing inter-strand cross-links; and (2) the production of (1)O(2). CCT is an efficient producer of (1)O(2), more so than 8-methoxypso-ralen, and is responsible for cell-membrane damage and cellular edema.

In this paper, we report on 366 East Indian patients with vitiligo who were treated for 2 to 3 years with either 8-methoxypsoralen (8-MOP), 4,5',8-trimethylpsoralen (TMP), or psoralen and sunlight. These patients with amelanotic macules had 10 to 70% skin involvement of 1 to 50 years duration. Male and female patients from ages 12 to 70 years were randomly assigned to 8 treatment groups; the study was conducted on a double-blind protocol. Patients in prone and supine positions were exposed to the sun for 45-60 minutes in gradually increasing doses between 11 a.m. and 2 p.m. thrice weekly and 2 hours after oral ingestion of the drug. The various drug dosage schedules investigated included 9 groups: 0.3 and 0.6 mg 8-MOP/kg; 0.8, 1.8, and 3.6 mg TMP/kg; a combination of 0.3 mg 8-MOP and 0.6 mg TMP/kg; 0.6 and 1.2 mg psoralen/kg, and a placebo. For ethical reasons, the placebo group was terminated after 9 to 12 months of therapy. All patients were photographed before enrollment and at intervals of 6, 12, 18, and 26 months during therapy. Of these patients treated for nearly 2 years, the faces of those 45% receiving the combination dose of 8-MOP plus TMP or low-dose 8-MOP (0.3 mg/kg) were fully repigmented, and nearly 60% achieved 75 to 100% repigmentation of the head and neck. The chest, abdomen, and back were repigmented nearly as well and better than the arms and legs. The patients receiving high-dose schedules of TMP and psoralen achieved better repigmentation response than those on lower dosage but still not as good as patients on 8-MOP or the combination group of 8-MOP plus TMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Furocoumarins (psoralens) are potent skin photosensitizing agents that are used in combination with long-wavelength ultraviolet radiation (320-400 nm) in the treatment of psoriasis and other skin diseases. Twelve linear and angular psoralens, capable of forming monofunctional and bifunctional adducts with DNA, were examined with a view to elucidate the role of 1O2 and O2-. in evoking skin photosensitization reactions and skin carcinogenesis. The results showed that both linear psoralens (capable of forming interstrand cross-links) and isopsoralens (angular, monofunctional type) and 3-carbethoxypsoralen (a linear and monofunctional type) produced 1O2 and O2-., although at varying degrees. Psoralen and 3-carbethoxypsoralen produced 1O2 greater than isopsoralens (angelicins). However, nonphotosensitizing angelicin, 5-methylangelicin, and 4,8-dimethyl-5'-carboxypsoralen produced 1O2 greater than 8-methoxypsoralen and 5-methoxypsoralen. The three monofunctional angelicin derivatives (isopsoralens) produced more O2-. than 8-methoxypsoralen, 5-methoxypsoralen, and 3,4'-dimethyl-8-methoxypsoralen. 3-Carbethoxypsoralen, a potent generator of 1O2 and a moderate producer of O2-., was highly photolabile. Until recently, skin photosensitization reactions (erythema, edema, damage to DNA or the membrane of cutaneous cells, the inhibition of scheduled DNA synthesis and skin carcinogenesis, etc.) were believed to involve photocyclo-addition of psoralens to DNA mediated by a type-I or anoxic reaction (a sensitizer-substrate interaction through the transfer of hydrogen atoms or electrons, but no direct involvement of molecular oxygen). Oxygen-dependent sensitized photodynamic reactions of type-II, involving the production of reactive oxygen (1O2 and O2-.), were believed not to mediate psoralen photosensitization reactions. We suggest that 1O2 and O2-. may also participate in skin photosensitization and cell membrane-damaging reactions. The fact that certain monofunctional isopsoralens produce 1O2 and O2-. at rates comparable to or better than bifunctional psoralens suggests that these reactive moieties of oxygen could play a major role in explaining their recently observed carcinogenic property and cell membrane-damaging reactions (e.g., edema or inflammation, etc.).

Melasma is a circumscribed brown macular hypermelanosis of the areas of the face and neck that are exposed to light. Clinical trials with various depigmenting formulations containing hydroquinone were conducted to determine the ideal concentration of hydroquinone, retinoic acid, and corticosteroids for the treatment of melasma. The compounds were tested with and without the concomitant use of topical sunscreen preparations. Based on the results of the trials and our earlier clinical experience, we conclude that treatment of melasma should involve the following: avoidance of sun exposure, constant use of broad-spectrum sunscreens, and topical application of a cream or lotion containing 2% hydroquinone and 0.05% to 0.1% retinoic acid (tretinoin). Patients should suspend use of oral contraceptives and other agents that promote skin pigmentation. The monobenzyl ether of hydroquinone should never be used in melasma therapy.

Albino guinea pigs were treated with psoralen derivatives plus 320--400 nm ultraviolet radiation, and DNA was extracted from their epidermis. The DNA was assayed for the presence of interstrand cross-links by standard denaturation-renaturation assays and by a new technique, electron microscopy of the DNA under totally denaturing conditions. The latter method allows individual cross-links to be directly observed and counted. When either 4,5',8-trimethylpsoralen or 8-methoxypsoralen was applied topically to the skin (8--20 microgram/cm2) or administered orally (10--12 mg/kg body weight), followed by exposure to 320--400 nm ultraviolet radiation, most of the epidermal DNA was found to contain a high frequency of cross-links. For example, oral or topical trimethylpsoralen treatment gave an average of one cross-link per 250 nucleotide pairs or about 3 . 10(5) cross-links per guinea pig chromosome. When the dose of either drug was decreased 20-fold to the level used in the clinical treatment of psoriasis, however, no cross-links coulld be detected in the epidermal DNA. The electron microscopic assay is sensitive enough that we can put an upper limit of 1 cross-link per 10(6) nucleotide pairs (80 cross-links per chromosome) for the low dose studies. The significance of these findings to the understanding of the effectiveness of psoralens in psoriasis therapy is discussed.

DNA repair in murine and guinea pig skin has been studied by the immunohistochemical method. For the detection of DNA photolesions in situ by the indirect immunofluorescence (IF) method two antisera directed against DNA-pyrimidine-dimers and DNA-psoralen-photoadducts have been applied. The IF assay enabled to detect the DNA photodamage induced by high UV-doses, exceeding more than fivefold minimal phototoxic response of the skin. It was found that IF staining gradually disappeared due to DNA repair, and at 48 h after UV-exposure both types of the DNA photolesions were no more detectable. Importantly, the IF method revealed that the persistence of DNA-pyrimidine-dimers could be traced for a longer time than that detectable by UV-endonuclease incision method.

Variegate porphyria (VP) is an autosomal dominant disease characterized in adults by mechanical fragility and blistering of sun-exposed skin or acute visceral and neurological manifestations. The laboratory diagnosis of VP depends on a search for high levels of coproporphyrin and protoporphyrin in the feces. Variegate porphyria has been infrequently diagnosed in the United States. In this study of five New England families with VP, there were nine manifest, six latent, and six questionable cases among 40 individuals studied. This report reviews the diagnostic approach to and treatment of affected individuals and their families.

The effects of pulsed nitrogen gas laser emission (337.1 nm wavelength) were studied on human skin. The laser provides high-intensity monochromatic UVA radiation and can elicit delayed erythema in an actual exposure time of about 1 msec (105,000 pulses, each lasting 10 nsec, delivered over 210 sec). The effects of nitrogen laser irradiation were compared clinically and histologically with conventional erythemogenic UVA and UVB exposures from xenon arc or mercury arc lamps and were found to be similar in many respects. The minimal erythema dose is comparable to that obtained using more conventional continuous light sources which have more than 100 times lower intensity. A phototoxicity comparison of oral and topically applied psoralens is presented, indicating that the laser may prove useful in comparing photosenitizing capacity of certain compounds.

This study was directed to examine the role of type II (photodynamic) reactions involving the production of reactive oxygen species (singlet oxygen, superoxide anion, and hydroxy radicals) in in vitro and in vivo photosensitization reactions induced by skin photosensitizing chemicals. Several porphyrins and psoralens, as model compounds representing examples of endogenous and exogenous photosensitizers, were examined for their ability to (a) produce singlet oxygen and superoxide anions, (b) induce damage to membranes and associated microsomal P-450, (c) promote lipid peroxidation of microsomal lipids of liver and epidermal cells, and (d) induce skin photosensitization reactions in vivo. Dose-response study in vitro of singlet oxygen production in H2O and D2O and inhibition studies involving the production of singlet oxygen and superoxide anion by specific quenchers indicated significant production of singlet oxygen by porphyrins, about 5-20 times higher than psoralen at 10(-5) M and 10(-6) M concentration and irradiation dose of 1-5 J/cm2 of UVA (greater than 320-400 nm radiation). The comparative studies on aerobic photodegradation of microsomal P-450 of guinea pig epidermis and liver indicated a significantly greater destruction of P-450 with porphyrins than with psoralens. A membrane-lipid peroxidation study involving malondialdehyde production, using liver and epidermal microsomal fractions with and without porphyrins, psoralens, and UVA radiation, indicated 10-20 times increased production of malondialdehyde with UVA and porphyrins than with psoralens.

The effect of EGF on the soft agar colony-forming ability of fresh human tumor cells was assessed in 40 specimens obtained from various types of carcinoma including those of the breast, endometrium ovary, and other sites. Cells from four established human tumor cell lines (three breast and one endometrial) were also included in this study. The results showed that addition of EGF at a concentration of 50 ng/ml resulted in a 50% higher cloning efficiency in soft agar in 40% of the samples of fresh human tumors. When cells from tumor cell lines were plated in semi-solid medium containing EGF, the number of colonies formed was at least twice as high as controls. Cells from fresh tumor biopsies were assayed for EGF receptors to determine whether the correlation between the proliferative response in EGF-supplemented semi-solid medium as compared to control could be related to the number of EGF receptors present on the cells. Specific receptors for EGF were detected by using radioiodinated EGF in early-passage cell cultures from some of the tumors tested for clonogenicity. The number of receptors ranged from 0.3 to 3.27 X 10(5) per cell. Cells from two melanoma specimens possessed less than 0.3 X 10(3) EGF receptors per cell. We found no correlation between the number of EGF receptor on a cell surface and the mitogenic effect of EGF on the same tumor cells grown in semi-solid medium.

Melasma is an acquired brown hypermelanosis of the face. Although it is thought that melasma is associated with multiple etiologic factors (pregnancy, gastric, racial, and endocrine), one of the primary causes of its exacerbation appears to be exposure to sunlight. Three patterns of melasma are recognized clinically: (1) a centrofacial pattern, (2) a malar pattern, and (3) a mandibular pattern. Examination of patients with Wood's light (320--400 nm) is useful in classifying the specific type of melasma in correlation with the localization of pigment granules (melanosomes) in the epidermis and dermis. Four types of melasma are described on the basis of Wood's light examination: (1) an epidermal type, (2) a dermal type, (3) a mixed type, and (4) a fourth type, described in patients of dark complexion, in which the lesions, for lack of contrast, are not discernible on Wood's light examination, perhaps due to the increased number of melanosomes in the normal skin of black individuals. Light, histochemical, and electron microscopic studies revealed an increase in number and activity of type-specific melanocytes which appeared to be engaged in increased formation, melanization, and transfer of pigment granules (melanosomes) to the epidermis as well as to the dermis. The melanocyte seems to undergo a functional alteration brought about by a combination of multiple factors, including persistent sun exposure, hormonal factors, and genetic predisposition.

The major source of color in human skin derives from the presence within the epidermis of specialized melanin-bearing organelles, the melanosomes. Tanning of human skin on exposure to ultraviolet light results from increased amounts of melanin within the epidermis. Melanosomes synthesized by melanocytes are acquired by keratinocytes and transported within them to the epidermal surface. In some cases, the melanosomes are catobolized en route. New information indicates that the multicellular epidermal melanin unit (melanocyte and associated pool of keratinocytes) rather than the melanocyte alone is the focal point for the control of melanin metabolism within mammalian epidermis. Gross human skin color derives from the visual impact of the summed melanin pigmentation of the many epidermal melanin units. In theory, constitutive skin color in man designates the genetically-determined levels of melanin pigmentation developed in the absence of exposure to solar radiation or other environmental influences; facultative skin color or "tan" characterizes the increases in melanin pigmentation above the constitutive level induced by ultraviolet light. The details of genetic regulation of pigment metabolism within the epidermal melanin units are being clarified. In some mammals at least, the function of epidermal melanin units is significantly influenced by hormones which may be regulated by radiations received through the eyes. Based on an evolutionary history of the human family which exceeds ten million years, it is proposed that melanin pigmentation may have played a number of roles in human adaptions to changing biologic and physical environments.

Recently a major metabolite of 4,5',8-trimethylpsoralen (TMeP) (a photochemotherapeutic agent), was isolated from the urine of mice and human volunteers receiving the drug orally; it was identified as 4,8-dimethyl-5'-carboxypsoralen. The synthesis of this compound has been carried out to obtain a distinct confirmation of the structure of the urinary metabolite and to study its photochemical and photobiological properties. The results obtained showed that this interaction and photoreaction with DNA are very poor; this fact can be correlated with the presence of the ionizable carboxylic group that undergoes a repulsion by the phosphate residues of the macromolecule. This hypothesis is confirmed by the higher interaction and photoreaction with DNA of the 4,8-dimethyl-5'-carboxypsoralen methyl ester in which, of course, the ionizable character is no more present. In connection with this very low photoreacting capacity with DNA, the synthesized metabolite proved lacking of photosensitizing effects on human and guinea pig skin. This fact provides an explanation of the very low photosensitizing properties of TMeP when given orally in contrast with the high activity after topical application.

8-methoxypsoralen, the most widely used psoralen in photochemotherapy, was shown to induce mixed-function oxidases. Induction of mixed-function oxidases in mouse liver was examined after mice were given a single dose of one of three psoralens. 8-methoxypsoralen clearly induced p-nitroanisole O-demethylase and slightly induced aryl hydrocarbon hydroxylase. Psoralen and 4,5',8-trimethylpsoralen failed to induce either enzyme. These results represent the first enzyme induction studies on these clinically useful compounds. The studies may have relevance in understanding the clinical differences in skin photosensitizing activity and photochemotherapeutic effectiveness of the compounds in such diseases as psoriasis and vitiligo.

In this article, practical and clinical aspects of photoprotection are discussed with emphasis on topical sunscreens. Protection against the adverse effects of sunlight includes prevention of the following: sunburn in normal individuals; acute phototoxic and photoallergic reactions; chronic skin damage (dermatoheliosis) and skin cancer; and specific disease-oriented responses (such as porphyria or polymorphous photodermatitis).