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Biomedical subjects

P Bonan

Publications and source records attributed to P Bonan.

15 recordsLinked to original sources
PubMed2003

Epilation with Nd:YAG laser: a brief analysis of the technical application methods, results and pre- and post-treatment procedures.

With the use of the so-called "selective" lasers, it is possible to operate specifically on the melanin as the absorbing target of undesirable hair. The optimal pulse duration for laser epilation should be found between the TRT of the epidermis (1-2 msec) and the TRT of the follicle (10-50 msec). For the thermal destruction of the follicle containing melanin, the ideal laser energy should (1) be absorbed in a selective manner with respect to other chromophores; (2) have a wavelength capable of penetrating in depth and reaching the target to be treated; and (3) be sufficient to destroy tissue targets (in the hair the papilla, the follicular epithelium, the so-called "bulge" and also the vascular support). With this method the melanin and the follicular structures are "heated" in a preferential manner while still safeguarding the adjacent skin structures. Numerous laser systems are employed in the treatment of undesirable hair with varying results according to the source, procedures, phototype, and pigmentation of the hair to be treated. The most frequent side effects may be discomfort or a slight burning sensation and un-aesthetic pigment changes or scarring. We report here our experience based on the treatment of 94 subjects over a 12 month period using the Nd:YAG laser (SMARTEPIL 2, Deka M.E.L.A., Italy). Our results indicate that a wavelength of 1064 nm is efficacious in obtaining a greater penetration and reaching the deeper follicles, with a greater respect for the skin due to the lower absorption by the melanin, and consequently a lower incidence of side effects.

Adult↗
PubMed2001

Nd:YAG 1064 nm laser in the treatment of facial and leg telangiectasias.

BACKGROUND: Facial and leg telangiectasias are a frequent cosmetic concern for both females and males with various skin types and ages. To date the different treatments for these problems, in particular leg telangiectasias, have frequently failed or led to negative side-effects. OBJECTIVE: This study examines the clinical effects and safety of applications with a 1064-nm Nd:YAG laser system (SmartEpil II, DEKA M.e.l.a., Florence, Italy) to treat vessels on the face and legs. MATERIALS AND METHODS: Twenty-five subjects with facial telangiectasias underwent one treatment at 100 J/cm2, 10 ms and 2 Hz repetition rate. Thirty-two subjects with leg telangiectasias, measuring 0.1-3 mm in diameter, were treated at 125-200 J/cm2, 10-30 ms and 2 Hz repetition rate. Subjects in this group underwent one to five treatment sessions at 8 week intervals. RESULTS: All subjects showed visible improvement, with 95-100% clearing of the face telangiectasias after only one treatment, and 50-100% clearing of the lower extremity vessels after three to five treatments. Transitory hypopigmentation was seen in two cases subjected to leg vessel treatment. CONCLUSIONS: Treatment of facial and leg telangectasias using a true long pulse 1064 nm Nd:YAG laser is an effective and safe method. The relative lack of discomfort combined with a high degree of individual satisfaction should play a part in the fairly high level of acceptance of this new form of therapy for the treatment of leg and face telangiectasias.

Adult↗
PubMed1991

The role of cyclosporine A in the treatment of pemphigus erythematosus.

Steroids are effective in the autoimmune bullous disease pemphigus; however, treatment may be difficult to sustain because of severe side effects. Cyclosporine A acts mainly on helper/inducer T lymphocytes and has few side effects at low doses. We report three patients with pemphigus erythematosus who had a relapse while receiving the maintenance dose of steroid therapy. All patients who were treated with both cyclosporine A (5 mg/kg/d) and prednisone (1 mg/kg/d) responded remarkably well to combined therapy. After clearing, prednisone was discontinued and cyclosporine A was reduced to 2 to 3 mg/kg/d. With this treatment, all patients have been virtually free of symptoms, have remained well, and have had normal laboratory values.

Adult↗
PubMed1991

The role of plasminogen activators in alopecia areata.

Plasminogen activators are serine proteinases which transform the serum zymogen, plasminogen, into plasmin, a broad-spectrum protease with fibrinolytic effect. Two main plasminogen activators have been described in humans: urokinase (UK; molecular weight, 55,000) and tissue-type plasminogen activator (tPA; molecular weight, 74,000). Thirteen subjects were studied who had alopecia areata (AA), nine in the active phase and four in remission. There were alterations in the perivascular and peribulbar fibrinolytic activity in the nine subjects in the active phase of disease, suggesting a possible role of plasminogen activators in AA. A modified Todd's autohistographic method was used to evaluate cutaneous fibrinolytic activity (which depended on the activity of plasminogen activators) in the 13 AA subjects and five volunteer controls. Cutaneous fibrinolytic activity was reduced in perivascular areas, but increased in peribulbar areas, in the nine subjects in the active phase of disease. Tests with monoclonal antibodies directed against the catalytic sites of tPA and UK showed that the perivascular fibrinolytic activity was tPA dependent, and the peribulbar fibrinolytic activity was UK dependent.

Adolescent↗
PubMed1990

Antipsoriatic therapies inhibit epidermal plasminogen activator activity.

Urokinase (UK, Mr 55,000) and tissue-type plasminogen activator (tPA, Mr 74,000) are serine proteinases involved in many biological processes, ie, cell migration, neoplastic transformation, and extracellular proteolysis. Cutaneous fibrinolytic activity (dependent on the activity of UK and tPA) was studied with the autohistographic fibrin film method in 40 patients affected by psoriasis vulgaris before and after topical (anthralin, betamethasone valerate, hydrocolloid occlusive dressing) or systemic psoralen-ultraviolet-light (PUVA) treatments. Autohistographic studies also were performed after apposition of monoclonal antibodies directed against the catalytic site of UK and tPA. Finally, UK and tPA were localized immunohistochemically in the psoriatic plaques and in controls using the immunoperoxidase procedure based on the biotin/avidin system. UK and tPA immunoreactivity was present in the cytoplasm and around the outlines of keratinocytes in the psoriatic patches before treatment and in the patches not cleared after treatment, while it was not detectable in normal epidermis, in the unaffected psoriatic epidermis, and in the cleared psoriatic skin. Cutaneous fibrinolytic activity was present in the cases in which UK and tPA were detected histochemically and, in the psoriatic epidermis, it was abolished by preincubation with anti-tPA but not with anti-UK antibodies. This study suggests that established topical and systemic treatments for psoriasis possess UK and tPA antagonist activity.

Adult↗
PubMed1989

Plasminogen activation in psoriasis.

Plasminogen activation is a widely documented physiological phenomenon in which plasminogen activators (mainly urokinase and tissue type plasminogen activator) transform the zymogen plasminogen into the wide-spectrum proteinase plasmin. We show here that psoriatic epidermis is provided with abnormal plasminogen activator activity, mainly dependent on the activity of tissue type plasminogen activator and that this abnormal activity can be reversed with common topical treatments (i.e. anthralin, and 0.1% betamethasone valerate cream). We also report abnormal immunohistochemical localization of plasminogen, urokinase and tissue type plasminogen activator in psoriatic epidermis which returned to normal after the topical treatments. These data suggest a major role of plasminogen activation in the pathogenesis of psoriasis.

Adult↗
PubMedDate not supplied

[Echography applied in dermatologic diseases. A comparative preliminary study of the use of high-frequency transducers].

Ultrasonography (US) was first used in dermatology in 1979. During the last few years, US has evolved thanks to technological progress and its use has been on the increase, in dermatology, to study both localized and diffuse skin diseases. In this paper, the authors review and compare the results obtained with a 20 MHz transducer with those obtained with 7.5 MHz and 10 MHz transducers in the study of skin alterations. Three parameters were considered: lesion identification, spatial evaluation and US structure. Fifty-eight cases of localized and 48 of diffuse skin diseases were examined. The localized forms were benign in nature in 18 patients (3 nevi, 2 seborrheic keratoses, 3 ulcus cruris cases, 6 sebaceous and 2 liquid cysts). The other 40 patients had malignant neoplastic lesions (16 epitheliomas, 13 primitive melanomas, 1 metastatic melanoma, 8 lymphomas and 2 Kaposi's sarcomas). The 48 cases of diffuse conditions included 27 systemic sclerosis, 18 psoriasis and 3 lichen planus cases. The comparative analysis of the results obtained using the different types of transducers in the study of localized dermatoses showed no differences in lesion identification and in the depiction of their US features. On the other hand, the 20 MHz transducer was much more accurate than the others as regards the spatial evaluation of the lesions measurable in millimeters, whereas it poorly demonstrated the lesions > 1.5 cm. However, only the 20 MHz transducer could demonstrate the US features of diffuse conditions.

Evaluation Studies as Topic↗