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Biomedical subjects

A Tanew

Publications and source records attributed to A Tanew.

At least 37 records · Page 2Linked to original sources
PubMed2000

Keratinocytes express the CD146 (Muc18/S-endo) antigen in tissue culture and during inflammatory skin diseases.

The CD146 (or MUC18/MEL-CAM) antigen is a cell adhesion molecule of the immunoglobulin superfamily. Besides in melanoma, expression of CD146 antigen has been demonstrated in breast epithelia and hair follicles. We studied its expression by human keratinocytes in culture as well as in neoplastic and inflammatory skin diseases. Staining of primary cultured keratinocytes revealed expression of CD146 on the cell membrane, preferentially on cell-cell contact sites. Western blot analysis of keratinocytes detected a band of approximately 113 kDa, corresponding to the CD146 protein. In contrast to primary keratinocytes, neither CD146 protein nor mRNA expression was found in the keratinocyte-derived cell lines A431 and HaCaT. Treatment of keratinocytes with the proinflammatory cytokines interleukin-1 and interleukin-6, tumor necrosis factor-alpha, and interferon-gamma, resulted in no change of CD146 expression and incubation with phorbol 12-myristate 13-acetate led to a reduction of CD146 on keratinocytes. By contrast, when culturing keratinocytes in medium devoid of growth supplements, a distinct upregulation was observed as compared with culture in fully supplemented medium. In normal human epidermis expression of the CD146 antigen was not detectable. It was strongly upregulated, however, on suprabasal keratinocytes in psoriasis, in lichen planus, in the epidermis overlying skin neoplasms, and in viral warts. In squamous cell carcinomas and basal cell carcinomas only a minority of tumor cells expressed CD146. Our findings suggest that the CD146 antigen represents an activation marker of keratinocytes and may be involved in cutaneous inflammatory tissue reaction.

Antigens, CD↗
PubMed1999

Narrowband UV-B phototherapy vs photochemotherapy in the treatment of chronic plaque-type psoriasis: a paired comparison study.

OBJECTIVE: To compare the therapeutic efficacy of narrowband (TL-01) UV-B phototherapy vs photochemotherapy (psoralen-UV-A [PUVA]) in patients with chronic plaque-type psoriasis. DESIGN: Open, nonrandomized, intraindividually controlled paired comparison study. SETTING: Phototherapeutic unit in a university hospital. PATIENTS: Twenty-five patients with chronic plaque-type psoriasis. INTERVENTIONS: Paired irradiations with threshold erythemogenic doses of narrowband UV-B and PUVA were given to the patients' dorsal aspect including the arms and legs. Treatment was performed 3 times weekly until complete or almost complete clearing with one or both regimens or over a maximum period of 18 exposures. MAIN OUTCOME MEASURES: Assessment of the Psoriasis Area and Severity Index (PASI) in each half of the patient's dorsal aspect before and after treatment with the 2 regimens. RESULTS: The median pretreatment PASI score of 16 (range, 6.2-23.4) was reduced by 84% to 2.5 (range, 0-12.6) by the narrowband UV-B treatment and by 89% to 1.8 (range, 0-8.2) by the PUVA treatment. Statistical analysis of these data showed a tendency for PUVA being superior to narrowband UV-B although the difference remained below the level of significance (P = .17). However, a clear effect of the pretreatment PASI score on the therapeutic outcome was found. Patients with higher baseline PASI scores responded significantly better to PUVA than to narrowband UV-B (P = .03). CONCLUSIONS: Our data demonstrate that in many patients with plaque-type psoriasis, narrowband UV-B is comparably as effective as PUVA and, given the lack of photosensitizer-related adverse reactions and the possibly lower long-term cancer risk, can be considered as first-line treatment. Treatment with PUVA, on the other hand, remains the mainstay for patients with high PASI scores who do not respond or whose psoriasis cannot be controlled adequately by narrowband UV-B.

Chronic Disease↗
PubMed1999

Half-side comparison of erythemogenic versus suberythemogenic UVA doses in oral photochemotherapy of psoriasis.

BACKGROUND: Early American and European multicenter trials on the efficacy of photochemotherapy (PUVA) for psoriasis have clearly shown that the treatment protocol has a crucial impact on the cumulative UVA dose required for clearing patients. Most, if not all, treatment protocols rely on the PUVA-induced erythema as a guideline for UVA dosimetry. OBJECTIVE: Our aim was to investigate whether phototoxic erythema is integral to an optimized PUVA protocol or reflects an unnecessary overexposure of patients. METHODS: A standard high-dose UVA regimen using minimal phototoxic doses (MPD) was compared against two different low-dose regimens. To this purpose a bilateral comparison study was performed on 31 patients and divided in two parts. In the first trial on 14 patients, half of each patient's body was irradiated at each visit with 1 MPD, whereas the other half received only two thirds of the MPD. In the second trial on 17 patients treatment with 1 MPD was compared against treatment with one half of the MPD. RESULTS: A total of 27 patients (12 patients in the first trial, 15 patients in the second trial) completed the study. In both trials the suberythemogenic doses were therapeutically as effective as the minimal phototoxic doses. CONCLUSION: We conclude that PUVA-induced erythema is not a prerequisite for effective psoriasis treatment and that a low-dose UVA regimen is a promising approach to increase the short- and long-term safety of photochemotherapy.

Administration, Oral↗
PubMed1999

Ultrastructural changes in PAM cells after photodynamic treatment with delta-aminolevulinic acid-induced porphyrins or photosan.

Photodynamic therapy (PDT) is the combination of a photosensitizing drug (Ps) with light in the presence of oxygen leading to the generation of reactive molecular species and destruction of cancer cells. In this study we compared PDT with two Ps, the hematoporphyrin derivative Photosan (Ph) and delta-aminolevulinic acid (ALA)-induced endogenous protoporphyrin IX, with respect to mitochondrial function and ultrastructural alterations. The effects of PDT were investigated in PAM 212 cells after different Ps incubation times, light doses, and post-treatment periods. Both Ps induced a light dose-dependent impairment of the mitochondrial function with the dose-response curve being steep for ALA and flat for Ph. The prolongation of the incubation time from 4 to 20 h resulted in an increased reduction of mitochondrial activity after ALA PDT but not after Ph PDT. Treatment with an irradiation dose that decreased mitochondrial activity by 50% (IC50) led to early and profound changes of mitochondrial morphology in ALA photosensitized cells, whereas photosensitization with Ph resulted in more pronounced alterations of lysosomes. We conclude that at bioequivalent sublethal PDT exposures of PAM 212 cells, ALA-induced damage is primarily restricted to mitochondria, whereas Ph-induced cytotoxicity is mediated by damage of the lysosomal system.

Aminolevulinic Acid↗
PubMed1996

Skin tumors in photochemotherapy for psoriasis: a single-center follow-up of 496 patients.

BACKGROUND: The significance of oral psoralen photochemotherapy (PUVA) for the development of nonmelanoma skin cancers (NMSC) is still controversial. OBJECTIVE: We evaluated 496 psoriatics, who received PUVA treatment according to the European PUVA protocol in order to reassess the influence of the cumulative UVA dose on the development of NMSC and to answer the question if there is a UVA threshold dose above which the carcinogenic risk is increased. METHODS: The study was conducted as a retrospective investigation. All patients were seen personally. Age, sex, skin type, cumulative UVA dose and carcinogenic risk factors (arsenic, X-rays, tar, UVB, methotrexate) were recorded and investigated by marginal (MA) and partial effects analyses (PA) according to the Cox regression model. RESULTS: In 14 patients (2.8%), one or multiple histologically confirmed NMSC were diagnosed. Nine patients (1.8%) had squamous cell carcinoma (SCC), 5 patients (1.0%) had basal cell carcinoma (BCC). No patient had both types of NMSC. None of the SCC had metastasized. By taking the appearance of BCC and SCC as the endpoint, arsenic [MA: relative risk (RR) = 7.62; PA:RR = 5.36], tar (MA:RR = 4.51; PA:RR = 3.83) and methotrexate (MTX; MA:RR = 4.97; PA:RR = 4.07) appear to produce strong and significant effects (p < 0.05), both in MA and PA. Using the endpoint SCC only, the effect of the natural logarithm of UVA (ln UVA; RR = 2.47), arsenic (RR = 11.2), tar (RR = 9.92) and MTX (RR = 7.1) is significant (p < 0.05) in MA. In PA, only the effect of arsenic (RR = 5.19) is strong and significant (p < 0.05) while the effects of tar (RR = 7.85), MTX (RR = 3.22) and ln UVA (RR = 2.77) are strong but of borderline significance (p = 0.05-0.11). Nonlinear effects of ln UVA on the risk of SCC were far from significant (p > 0.2). CONCLUSION: PUVA with the European treatment protocol appears to be only a weak carcinogen by itself for SCC with a linear increase in tumor risk but not for BCC development.

Administration, Oral↗
PubMed1993

Lethal photosensitization by endogenous porphyrins of PAM cells--modification by desferrioxamine.

The effects of exogenous delta-aminolevulinic acid (ALA) on cultured PAM 212 cells were investigated. PAM cells exposed to ALA produce an excess of products of the heme biosynthesis pathway within hours. The endogenous porphyrins render the cells photosensitive in a time-, ALA dose- and irradiation-dependent manner. Independently of the ALA-induced photosensitized processes, ALA itself reduces the proliferation rate of PAM cells during the exponential growth phase. Iron deprivation by addition of the chelating agent desferrioxamine (df) accelerates the photosensitizing process, and thus makes it more efficient at lower ALA concentrations. The effects of df were compared with the effects of manganese-df and iron-df. The results indicate that iron trapping is the most important factor for the potentiation of ALA-stimulated photodynamic sensitization as well as for the dark toxicity. Iron complexing agents may thus be used to optimize ALA effects in the photodynamic treatment of cutaneous neoplasms with endogenous porphyrins.

Aminolevulinic Acid↗
PubMed1993

UVA does not photoreactivate pyrimidine dimers in cultured human fibroblasts.

Pyrimidine dimers were induced in duplicates of cultured human skin fibroblasts by irradiation with various doses of UVB radiation. Subsequently, one set of cells was further exposed to either 5 or 10 J/cm2 of UVA radiation to assess the photoreactivating activity of this spectral range in a human cell system. Following irradiation, pyrimidine dimers were quantified in all cells by determining the number of endonuclease-sensitive sites (ESS). No difference in the yield of ESS was observed between cells which had been irradiated with UVB only as compared to cells which subsequently had been exposed to 5 or 10 J/cm2 UVA. In contrast, subsequent exposure of UVB-irradiated cells of Monodelphis domestica to 10 J/cm2 UVA resulted in an almost 50% reduction of UVB-induced pyrimidine dimers. These data indicate that UVA does not induce photoenzymatic repair in human fibroblasts.

Adult↗
PubMed1991

Photochemotherapy for severe psoriasis without or in combination with acitretin: a randomized, double-blind comparison study.

In a randomized, double-blind comparative study 60 patients with severe, widespread psoriasis were treated either with photochemotherapy (PUVA) alone or in combination with acitretin. Forty-eight patients completed the study; of these, 25 received placebo combined with PUVA and 23 received acitretin with PUVA. Marked or complete clearing of psoriasis occurred in 80% of the patients (20 of 25) without acitretin and in 96% of the patients (22 of 23) with adjunctive acitretin administration. The mean cumulative UVA dose given to patients in the acitretin-PUVA group was 42% less than that required for patients in the placebo-PUVA group. We conclude that acitretin substantially augments the efficacy of photochemotherapy in the treatment of severe psoriasis.

Acitretin↗
PubMed1991

Relative efficacy of 335 and 365 nm radiation in photochemotherapy of psoriasis.

The action spectrum for the induction of phototoxic erythema by treatment with 8-methoxypsoralen (8-MOP) and UVA peaks at around 335 nm. Because earlier investigations reported peak phototoxic activity at 365 nm, we compared the antipsoriatic efficacy of 335 and 365 nm in an oral psoralen photochemotherapy (PUVA) regimen using a monochromator. PUVA with 335 nm was twice as effective as with 365 nm, with respect to both erythemogenicity and the cumulative dose required for clearing psoriasis. However, 335 and 365 nm were equally effective if delivered in equal erythema doses. It appears that in human skin the antipsoriatic activity of 8-MOP parallels its erythemogenicity.

Dose-Response Relationship, Radiation↗
PubMed1990

Cyclosporin A in combination with photochemotherapy (PUVA) in the treatment of psoriasis.

Forty patients with relapsing plaque psoriasis involving more than 20% body surface were treated either with cyclosporin A (CyA) plus PUVA or the retinoid etretinate plus PUVA (RePUVA). They initially received either CyA (2 weeks) or etretinate (1 week) alone and then PUVA was given concomitantly until complete remission. The patients were monitored over a period of 6 months and any relapse recorded. With each combined treatment regimen, CyA plus PUVA and RePUVA, the patients cleared within comparable periods of time (mean treatment period of 5.3 vs. 4.7 weeks after initiation of therapy and 3.3 vs. 3.7 weeks after initiation of PUVA). However, the cumulative UVA dose required for clearance (110.9 J/cm2 vs. 62.1 J/cm2 (P less than 0.05)) and the incidence of severe and early relapses were significantly higher in the CyA cohort. Within 6 months severe relapses had occurred in 58% of CyA plus PUVA but only in 15% of RePUVA-treated patients (P less than 0.001). This suggests that the CyA plus PUVA regimen as performed in this study is less effective than RePUVA.

Adult↗
PubMed1989

Photosensitizing compounds in the treatment of psoriasis.

Photosensitizers were first used to treat psoriasis 15 years ago when the phototoxic reaction of psoralens and UVA was found to induce remissions of the disease. The effect of this reaction on DNA, particularly the formation of cross-links, was thought to be the decisive event. Strong cross-linking agents such as 8-MOP, TMP and 5-MOP are clinically effective whereas most compounds which produce only monofunctional adducts are virtually ineffective. Orally administered 8-methoxypsoralen (8-MOP) is the most widely used compound. 4,5',8-Trimethylpsoralen (TMP) is poorly absorbed from the intestine but has marked efficacy when applied topically. 5-MOP may be a useful alternative to 8-MOP because it is less erythemogenic and does not cause nausea. These three furocoumarins appear to be similar photochemically and may introduce similar risks. However, the photobiological properties of furocoumarins can be modified by altering one or more parts of the molecule. Such modifications might yield effective analogues with reduced cytogenetic hazards. Several psoralens and angular furocoumarins are being tested for effectiveness combined with fewest long-term side-effects, especially carcinogenesis. Encouraging preliminary results have been obtained with 7-methyl-pyridopsoralen and 4,6,4'-trimethylangelicin. Other important approaches to increasing the safety of photochemotherapy may be the use of different photoactivating wavelengths or the introduction of new classes of photosensitizers.

Humans↗
PubMed1989

Photosensitivity and hyperpigmentation in amiodarone-treated patients: incidence, time course, and recovery.

Amiodarone (AD) induces photosensitivity in 75% of the patients treated with this drug. Phototoxic reactions can be experimentally elicited with UVA but not with UVB. The UVA-MED is significantly reduced after 12 months of treatment. The development of photosensitivity depends on the total dose of AD; 40 g is the minimal cumulative dose requirement. Under the regimens commonly used, photosensitivity can be expected after 4 months of continuous AD treatment and appears to be unrelated to the skin type. Photosensitivity gradually decreases and returns to normal between 4 and 12 months after the withdrawal of AD. AD-related hyperpigmentation develops after an average of 20 months of continuous AD treatment and a minimal total dose of 160 g AD in about 8% of the patients (mainly of skin type I). Electron microscopic examination of the sun-exposed skin of patients without AD discoloration shows pigment deposits similar to those already described in patients with AD hyperpigmentation in exposed and non-exposed skin. Light and electronmicroscopic examination of sun-exposed skin of both clinically photosensitive and non-photosensitive patients reveals perivascular inflammation even in the absence of a clinical rash. Reduplications of vascular basal laminae occur in sun-exposed skin of both patients with and without UVA photosensitivity but are absent from non-exposed skin. In one patient, followed for 33 months after drug withdrawal, massive AD-induced hyperpigmentation was found to be reversible.

Amiodarone↗
PubMed1988

[Penicillin-induced acute renal failure as a rare severe complication of erysipelas treatment].

Penicillins are the most commonly used antibiotics in dermatology owing to their bacteriocidal effect and the high responsiveness of most bacterial dermatoses to penicillin treatment. Although there is a wide range of adverse reactions to penicillins, severe complications are seen very rarely. We report on two cases of penicillin-induced acute interstitial nephritis and summarize the characteristic features of this serious adverse reaction to penicillin administration.

Acute Kidney Injury↗
PubMed1988

Treatment of vitiligo with khellin and ultraviolet A.

Twenty-eight patients with vitiligo were treated with a new photochemotherapeutic regimen using khellin, a furanochromone, as photosensitizer, together with ultraviolet A (UVA) irradiation. Twenty-five patients received khellin orally and three patients were treated with topical khellin. Treatments were given three times weekly. As opposed to psoralens, khellin did not induce skin phototoxicity with UVA but it induced repigmentation similar to psoralens. The treatment success strongly depended on the number of treatments. More than 70% repigmentation was achieved in 41% of the patients who had received 100 to 200 treatments. This success rate is comparable to the rate obtained with psoralens. Seven patients experienced a mild elevation of liver transaminases within the early treatment phase and their treatments were discontinued. No long-term internal organ or skin toxicity was observed. The major advantage of khellin is that it does not lead to phototoxic skin erythema and thus can be considered safe for home treatment. Because of its photochemistry it may be considered less hazardous than psoralens regarding mutagenicity and carcinogenicity.

Adolescent↗
PubMed1988

5-Methoxypsoralen (Bergapten) for photochemotherapy. Bioavailability, phototoxicity, and clinical efficacy in psoriasis of a new drug preparation.

In a previous study we evaluated a microcrystalline preparation of 5-methoxypsoralen (5-MOP; Bergapten) for its photochemotherapeutic properties. Preliminary data indicated that the clinical efficacy of 5-MOP is comparable to that of 8-methoxypsoralen. 5-MOP appeared as a promising alternative photosensitizer for the management of psoriasis because of the almost complete lack of phototoxic and drug intolerance reactions that are frequently encountered in patients undergoing 8-MOP photochemotherapy. With a new liquid preparation of 5-MOP we have now extended our earlier investigation on a larger clinical scale and have correlated the clinical response with the bioavailability of the drug. Serum level determinations showed an absorption rate of only approximately 25% that of 8-MOP. When administered in the same dosage as 8-MOP, 5-MOP turned out to be significantly less effective; however, by doubling the oral dosage, comparable results in terms of clearing of psoriasis were obtained. Also with this high-dose 5-MOP regimen, no drug intolerance was noted and other side effects, such as severe erythema, pruritus, and nausea, occurred only rarely. We propose 5-MOP as a valuable alternative for photochemotherapy (PUVA) of PUVA-responsive diseases.

5-Methoxypsoralen↗