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Biomedical subjects

A Giannetti

Publications and source records attributed to A Giannetti.

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

S. aureus PFGE patterns of lesional or non lesional strains from patients with impetigo: association of individual bands with lesional or non lesional areas.

PFGE has been extensively used to obtain a reliable intra-species differentiation, although this technique has not been completely standardized. In this study, PFGE was applied to analyze in detail the patterns of 19 lesional S. aureus strains isolated from patients with impetigo, compared with 15 non-lesional strains isolated from nasal or pharyngeal swabs of the same patients. The strain DNA was extracted and processed as previously reported, using the strictest protocol to limit the variations between different analytical sets. To obtain maximum sensitivity and comparability, the electrophoresis patterns were analyzed by an automated and computerized reader (GelDoc1000). The DNA fragments (range 12-15 bands) obtained for each individual strain were then divided into 39 zones including from 1 to 4 bands for a total of at least 91 possible different gel positions. The positivity for each zone (and/or the positivity for the individual bands contained) was associated with the lesional/non-lesional origin and with the face localization of the strains.

DNA, Bacterial↗
PubMed2000

Pathogenetic mechanisms of atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory disease which results from complex interactions between genetic and environmental mechanisms. An altered lipid composition of the stratum corneum is responsible for the xerotic aspect of the skin and determines a higher permeability to allergens and irritants. Keratinocytes of AD patients exhibit a propensity to an exaggerated production of cytokines and chemokines, a phenomenon that can have a major role in promoting and maintaining inflammation. Specific immune responses against a variety of environmental allergens are also implicated in AD pathogenesis, with a bias towards Th2 immune responses. In particular, dendritic cells expressing membrane IgE receptors play a critical role in the amplification of allergen-specific T cell responses. Cross-linkage of specific IgE receptors on dermal mast cells provokes the release and synthesis of a vast series of mediators. Following their recruitment and activation into the skin, eosinophils are also thought to contribute relevantly to tissue damage. Thus, a complex network of cytokines and chemokines contributes to establishing a local milieu that favors the permanence of inflammation in AD skin.

Allergens↗
PubMed1999

Communication: expression of the novel inhibitor of apoptosis survivin in normal and neoplastic skin.

Apoptosis plays a fundamental part in epidermal homeostasis, and apoptotic cells have been detected in normal and diseased skin. Little is known, however, on the inhibitory mechanisms of apoptosis at the skin level. In addition to bcl-2, a novel inhibitor of apoptosis designated survivin and structurally analogous to IAP apoptosis inhibitors has been recently identified. The expression of survivin in normal and pathologic skin was investigated. Immunohistochemical studies revealed that survivin is expressed in basal keratinocytes, but not in suprabasal epidermal layers, with a pattern similar to bcl-2. In western blots, the anti-survivin antibody recognized a single band of 16.5 kDa in protein extracts from normal human keratinocytes in culture, in agreement with the predicted size of survivin. In addition, survivin immunoreactivity was detected in benign and malignant melanocytic lesions, with strong expression in invasive lesions of melanomas. Whereas survivin staining was undetectable in benign epithelial tumors, such as seborrheic keratoses, it was observed in all epidermal layers in Bowen's disease. Interestingly, at variance with bcl-2, survivin was markedly expressed in squamous cell carcinoma, but virtually lacking in basal cell carcinoma, suggesting that these two apoptosis inhibitors may act through different anti-apoptotic pathways. Deregulation of survivin may influence both epidermal homeostasis and the development of melanoma and nonmelanoma skin cancer.

Adult↗
PubMed1999

Nerve growth factor protects human keratinocytes from ultraviolet-B-induced apoptosis.

Ultraviolet radiation is a potent inducer of apoptosis, whereas autocrine nerve growth factor protects human keratinocytes from programmed cell death. To evaluate the role of nerve growth factor in the mechanisms of ultraviolet B-induced apoptosis, cultured human keratinocytes were ultraviolet B irradiated following pretreatment with K252, a specific inhibitor of the tyrosine kinase high-affinity nerve growth factor receptor. Here we report that the addition of K252 significantly enhanced keratinocyte apoptosis. We then transfected normal human keratinocytes with pNUT-hNGF. Nerve growth factor overexpressing keratinocytes secreted the highest amounts of nerve growth factor in culture supernatants, were more viable, and had a higher rate of proliferation than mock-transfected cells. Whereas ultraviolet B radiation downregulated nerve growth factor mRNA and protein as well as the tyrosine kinase high-affinity nerve growth factor receptor in normal keratinocytes, it failed to do so in nerve growth factor-transfected cells. Moreover, nerve growth factor overexpressing keratinocytes were partially resistant to apoptosis induced by increasing doses of ultraviolet B at 24 and 48 h. These results indicate that downregulation of nerve growth factor function plays an important part in the mechanisms of ultraviolet B-induced apoptosis in human keratinocytes. In addition, ultraviolet B caused a decrease in BCL-2 and BCL-xL expression in mock-transfected keratinocytes, but not in nerve growth factor overexpressing cells. Finally, nerve growth factor prevented the cleavage of the enzyme poly(ADP-ribose) polymerase induced in human keratinocytes by ultraviolet B. These results are consistent with a model whereby the autocrine nerve growth factor protects human keratinocytes from ultraviolet B-induced apoptosis by maintaining constant levels of BCL-2 and BCL-xL, which in turn might block caspase activation.

Apoptosis↗
PubMed1999

Digital videomicroscopy and image analysis with automatic classification for detection of thin melanomas.

The aim of our investigation was to evaluate the usefulness of a system composed of a digital videomicroscope equipped with a dedicated program for the quantitative characterization of various parameters of the clinically significant features of pigmented skin lesion (PSL) images, forming the basis for automatic differentiation of naevi and thin melanomas. In total 424 naevi and 37 melanomas (including 23 thinner than 0.75 mm) were considered. All the digital images were acquired, framed and analysed using the DBDermo-MIPS program (Biomedical Engineering Dell'Eva-Burroni), which calculates different parameters related to the geometry, the colour distribution and the internal pattern of the lesion. We also assessed the efficacy of an automatic classifier, trained for 100% sensitivity using a subset of PSL images (59 naevi and 19 melanomas), on a test set including 365 naevi and 18 melanomas thinner than 0.75 mm. Significant differences between values from benign and malignant PSLs were observed for most of the numerical parameters. Values from the training set underwent elaboration by means of multivariate discriminant analysis, enabling the identification of variables that are important for distinguishing between the groups in order to develop a procedure for predicting group membership for new cases (test set) in which group membership is undetermined. Going on the training set data, a threshold score was established, enabling each melanoma to be attributed to the right group. When the same threshold value was employed for discriminating between benign and malignant lesions in the test set, all the melanomas were correctly classified, whereas 30 out of the 365 benign lesions were attributed to the wrong group. Thus the specificity of the system reached 92%, whereas the sensitivity was 100%. Our data suggest that elaboration of videomicroscopic images by means of dedicated software improves diagnostic accuracy for thin melanoma. Since elaboration of an image requires only 60s using our system, all the parameter data are available in real time and can be immediately examined by the classifier, providing an instant aid to clinical diagnosis.

Databases, Factual↗
PubMed1999

Clinical trial of the efficacy and safety of oral etretinate with calcipotriol cream compared with etretinate alone in moderate-severe psoriasis.

BACKGROUND: The aim of this clinical trial was to assess the efficacy and safety of calcipotriol cream associated with oral etretinate compared with etretinate alone in the treatment of moderate-severe psoriasis. METHODS: This controlled multicenter trial, within patients (hemiparts), enrolled 86 in- or out-patients (62 males, 24 females), mean (+/-SD) age 57.1 +/- 14.2 years, with psoriasis vulgaris on both sides of the body, and mean (+/-SE) baseline PASI score (Psoriasis Area and Severity Index) 30.7 +/- 0.9. All patients took oral etretinate 50 mg/day and applied calcipotriol cream (50 microg/g) on one half of their body twice a day. Treatment was continued for 9 weeks, and patients were seen every 3 weeks. RESULTS: At the end of the first 3 weeks the PASI score indicated a significant clinical difference between the two sides of the body (P < 0.001, ANOVA), with a reduction of 50.7% in the score for the calcipotriol-treated half, compared with a 39% reduction for the untreated half. By the 9th week of treatment the PASI score was 81.4% lower on the treated half, and 70.3% on the untreated side (P < 0.001, ANOVA). CONCLUSIONS: These findings suggest that patients with moderate-severe psoriasis might benefit from treatment with etretinate plus calcipotriol, with the aim of achieving a faster response and an overall smaller total dose of etretinate.

Administration, Oral↗
PubMed1998

Squamous-cell carcinoma developing within anal lichen planus: report of a case.

AIM: We present a case of squamous-cell carcinoma developing within perianal lichen planus. This is a chronic or recurrent cutaneous and/or mucosal dermatosis affecting less than 1 percent of the population. Neoplastic degeneration of cutaneous lichen planus is rare; only one case of squamous-cell carcinoma developing within perianal lichen planus has been described up until now in the international literature. CASE REPORT: Our case involved a 68-year-old woman with chronic, long-term lichen planus spreading all over the vulva and perianal region and the mucosa of the anal canal, where squamous-cell carcinoma developed within the perianal lichen planus. Treatment consisted of wide, circular excision of the perianal skin and mucosectomy of the anal canal up to as far as 1 cm above the dentate line. Reconstruction was performed by means of two V-Y bilateral subcutaneous flaps. CONCLUSION: Wide excision was performed not only to remove the squamous-cell carcinoma but also the lichen planus to prevent recurrence of metachronous or synchronous squamous-cell carcinoma. Follow-up at one year after surgery showed no local recurrence of either lichen planus or squamous-cell carcinoma, which suggests that surgical removal should be the therapy of choice for long-term, chronic perianal lichen planus that has proved to be resistant to medical therapy.

Aged↗
PubMed1998

Ceramide and cholesterol composition of the skin of patients with atopic dermatitis.

Atopic dermatitis skin tends to be easily irritated and appears dry. These clinical peculiarities correspond to impaired barrier function and to increased transepidermal water loss (TEWL) values. A few studies suggest that a reduced amount of total ceramides (especially of ceramide 1) is responsible for functional abnormalities of the skin of atopic dermatitis patients. The aim of this study was to analyze the relationship between epidermal lipids and barrier impairment in the skin of patients with atopic dermatitis. The quantity of ceramides, cholesterol sulphate and free cholesterol of 47 patients with atopic dermatitis and 20 age- and sex-matched healthy subjects was assessed by cyanoacrylate stripping and thin layer chromatography. Capacitance and TEWL were recorded at the same site of the lipid sample. In patients with atopic dermatitis, the levels of ceramide 1 and 3 were significantly lower and values of cholesterol significantly higher with respect to healthy subjects. Moreover, the CER/CH ratio was significantly lower with respect to normal skin. Patients with active signs of eczema also had higher TEWL values and lower capacitance values. By contrast, patients with no active signs of atopic dermatitis had a normal barrier function and intermediate values of ceramides and cholesterols, when compared to patients with atopic dermatitis with active lesions and normal subjects. The quantity of ceramide 3 was significantly correlated with TEWL impairment. These findings suggest that a decrease in ceramides in the stratum corneum is involved in barrier impairment in atopic dermatitis skin. Our data confirm those of other authors and support the view that impaired metabolism of ceramides may be the cause of dry skin and impaired barrier function in atopic dermatitis.

Adolescent↗
PubMed1997

Granulocyte macrophage colony-stimulating factor is overproduced by keratinocytes in atopic dermatitis. Implications for sustained dendritic cell activation in the skin.

Lesional skin of atopic dermatitis (AD) harbors high numbers of dendritic cells with enhanced stimulatory capacity for T lymphocytes. In this study, lesional AD skin was shown to stain heavily in both epidermal and dermal compartments for GM-CSF, a cytokine crucial to dendritic cell functions. Keratinocyte cultures established from uninvolved skin of AD patients exhibited markedly increased spontaneous and PMA-stimulated release of GM-CSF compared with keratinocytes from nonatopic controls. Correspondingly, keratinocytes from AD patients showed higher constitutive as well as PMA-induced GM-CSF gene expression. Larger amounts of GM-CSF were produced by AD keratinocytes, also in response to IL-1alpha, but not after stimulation with LPS, lipoteichoic acid, or staphylococcal enterotoxin B. Hydrocortisone reduced GM-CSF gene expression and protein release in both atopic and control keratinocytes. Supernatants from atopic keratinocytes were able to strongly stimulate PBMC proliferation in a GM-CSF-dependent manner. Moreover, conditioned medium from PMA-treated AD keratinocytes, together with exogenous IL-4, could support phenotypical and functional maturation of peripheral blood precursors into dendritic cells. Enhanced production of GM-CSF by keratinocytes may contribute relevantly to the establishment and chronicity of AD lesions, in particular to the increased number, sustained activation, and enhanced antigen-presenting functions of dendritic cells.

Adolescent↗
PubMed1997

Primary cutaneous marginal zone B-cell lymphoma: a recently described entity of low-grade malignant cutaneous B-cell lymphoma.

Recently a new classification of primary cutaneous B-cell lymphomas (PCBCLs) has been proposed by the European Organization for Research and Treatment of Cancer (EORTC)--Cutaneous Lymphoma Project Group. The marginal zone B-cell lymphomas (MZLs) were not included as a distinct entity because of insufficient experience and controversial opinions. We have studied 32 patients (M:F ratio 1.5:1; age range 25-93 years; mean age 49.6 years; median age 50 years) to determine the diagnostic criteria of primary cutaneous MZL and the relationship with other low-grade malignant PCBCLs. For comparison, three patients with immunocytoma were included in the study. Clinically, patients presented with solitary or clustered reddish or red-brown papules, nodules, and plaques, sometimes surrounded by an erythematous halo. Histopathologic sections showed nodular or diffuse infiltrates involving the dermis and subcutaneous fat. Cytomorphologically small to medium-sized cells with indented nuclei and abundant pale cytoplasm (marginal zone cells, centrocyte-like cells) predominated. In addition, scattered blasts, lymphoplasmacytoid cells, and plasma cells were observed below the epidermis and at the periphery of the infiltrates. Reactive germinal centers were present in 75% of the cases. The three cases of immunocytoma showed a more monomorphous pattern with predominance of lymphoplasmacytoid cells. The marginal zone cells showed a CD20+, CD79a+, CD5- and Bcl-2+ immunophenotype. They expressed immunoglobulin G in the majority of the cases. Staining with the monocytoid B cell-related antibody KiM1p gave positive results in all specimens with a typical intracytoplasmic granular pattern. A monoclonal distribution of immunoglobulin light chains was observed in marginal zone cells in 75% of the cases. Germinal centers, when present, were either polyclonal or negative for both kappa and lambda light chains. Monoclonal rearrangement of the JH gene was detected via polymerase chain reaction (PCR) in 18 of 26 investigated specimens. Analysis in 12 patients of the bcl-2/immunoglobulin heavy chain gene rearrangement using PCR yielded negative results. Lesions were treated by surgical excision followed in some patients by local radiotherapy. Systemic antibiotic therapy was administered to three patients, with good response in two. The prognosis is excellent. After a mean follow-up of 47.9 months (range 6-252; median 24) all patients are alive without signs of systemic lymphoma. Primary cutaneous MZL represents a distinct clinicopathologic subtype of low-grade malignant PCBCL.

Adult↗
PubMed1997

1,25-dihydroxyvitamin D3, transforming growth factor beta1, calcium, and ultraviolet B radiation induce apoptosis in cultured human keratinocytes.

Apoptosis is a cellular process of self-directed suicide that plays a key role during morphogenesis and in the maintenance of homeostasis in continuously renewing tissues. Currently, apoptosis is detected mainly by gel electrophoresis of fragmented DNA and by typical ultrastructural features such as cell shrinkage and chromatin condensation. Recently, an in situ technique was developed that allows the detection of the apoptotic process in cells and the quantitation of apoptosis in cell populations. We applied this technique to evaluate the apoptotic process in cultured normal human keratinocytes under basic conditions and after stimulation with factors and agents that are presumed but have never been proved to induce apoptosis in these cells. Apoptosis was analyzed after stimulation with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], transforming growth factor beta1 (TGFbeta1), calcium, UVB, or tumor necrosis factor alpha (TNFalpha). All these factors except TNFalpha induced apoptosis in human keratinocytes. Whereas UVB and calcium were good apoptogenic stimuli at 6 and 24 h, respectively, the vitamin D derivative and TGFbeta1 induced apoptosis after 5 and 6 d in culture. Apoptosis was also established by DNA fragmentation and electron microscopy. Finally, TUNEL technique showed that the number of apoptotic cells increases slightly (5-10%) from 24 to 144 h even in untreated keratinocytes. Our studies indicate that factors normally involved in the regulation of cell growth and differentiation can also control apoptosis.

Apoptosis↗
PubMed1997

Autocrine nerve growth factor protects human keratinocytes from apoptosis through its high affinity receptor (TRK): a role for BCL-2.

Normal human keratinocytes synthesize and release nerve growth factor (NGF) and express both the low- and the high-affinity NGF receptor. Because NGF has been shown to rescue certain cell types from programmed cell death, we investigated the role of endogenous NGF in preventing keratinocyte apoptosis. We report here that apoptosis is induced in normal human keratinocytes in culture by blocking endogenous NGF signaling with either anti-NGF neutralizing antibody or K252, a specific inhibitor of the tyrosine kinase high-affinity NGF receptor. Apoptosis was assessed by DNA laddering, electron microscopy, and in situ nick end labeling technique. In anti-NGF-treated keratinocytes, the apoptotic process starts at 96 h, and is maximal at 120 h. After K252 treatment, apoptosis starts at 48 h and peaks at 120 h. Because the product of the bcl-2 proto-oncogene protects many cell types from apoptosis, we measured the levels of this protein in apoptotic keratinocytes. We found that both K252 and anti-NGF antibody strikingly downregulate bcl-2 expression, starting at 72 h. Furthermore, HaCat keratinocytes stably transfected with a plasmid containing bcl-2 cDNA fail to undergo apoptosis when treated with K252. These findings show that autocrine NGF acts as a survival factor for human keratinocytes in vitro through its high-affinity NGF receptor, possibly by maintaining constant levels of Bcl-2.

Apoptosis↗
PubMed1997

Parallel intraindividual evaluation of the vasoconstrictory action and the anti-allergic activity of topical corticosteroids.

The human skin blanching assay is a well established method for ranking the efficacy of corticosteroids after epicutaneous application. Vasoconstriction is a pharmacological activity, which correlates well with the clinical efficacy, the intensity of skin blanching after a single application under occlusion corresponding, generally, to the clinical efficacy after repeated application without occlusion. However, in studies dealing with the comparison between the vasoconstriction assay and the evaluation of the clinical effects on inflammatory skin diseases, some exceptions to this correlation have been reported. Therefore, in a pre-clinical phase, it would be useful to combine the blanching assay with at least one anti-inflammatory assay. In the present study the blanching assay and the allergic contact dermatitis inhibition test were performed in parallel, in order to compare the two testing procedures in the same group of subjects, utilizing standardized study designs supported by objective means of evaluation. Three commercial preparations of corticosteroids containing clobetasol propionate (CP), clobetasone butyrate (CB) and hydrocortisone acetate (HA), respectively, were employed both to treat nickel-induced positive patch test responses on the volar forearms, and to perform a vasoconstrictor assay on normal forearm skin in 16 nickel-sensitized healthy volunteers. For evaluating skin blanching, we employed colorimetric measurements, whereas for the quantitative determination of the inhibition of the intensity of allergic patch test reactions, 20 MHz B-scanning supported by image analysis was used. Both colorimetric and echogenicity values enabled us to distinguish between the three corticosteroids (at the 17 h evaluation and the 64 h assessment, respectively). A fair correlation was noted between colorimetric and echogenicity values. Both testing procedures ranked the three corticosteroids in the expected order. Corticosteroid preparations should be compared using methods which allow different effects to be simultaneously monitored, without involving a high number of patients. We are proposing this double procedure for the parallel intraindividual evaluation of the vasoconstrictory action and the anti-allergic activity of topical steroids.

Administration, Topical↗
PubMed1996

Neuropeptides, nerve growth factor and eczema.

Considerable evidence indicates that peripheral nerve fibres play an active regulatory role during eczematous reactions. Many basic features of the inflammatory process are potentially subject to neuropeptidergic modulation, such as vascular changes, cellular trafficking activation and trophism in vivo and in vitro investigations suggest that neuropeptides are part of the complex network of mediators that initiate and maintain the eczematous process in the skin. In general, peptidergic fibres seem to exert a global protective role, but with specific and selective effects in the different phases. Evidence that the inflammatory process induces bio-chemical changes at a neuronal level has also been obtained. The possible mediators of the neuronal recruitment in the course of the eczematous reaction are still unknown. Nevertheless, nerve growth factor, which is locally increased during inflammatory processes and may induce peptidergic alterations, should be considered as a potential candidate molecule.

Animals↗
PubMed1996

Cultured human Langerhans' cells are superior to fresh cells at presenting native HIV-1 protein antigens to specific CD4+ T-cell lines.

Cultured Langerhans' cells (CLC) exhibit enhanced antigen-presenting function compared to freshly isolated LC (FLC), but they are commonly believed to be inefficient at processing intact proteins. In this study, FLC and CLC from normal, human immunodeficiency virus (HIV) seronegative volunteers were compared for their ability to present the HIV-1 envelope glycoprotein gp120 or reverse transcriptase (p66) antigens to autologous, specific CD4+ T cell lines. Epidermal cell suspensions enriched for LC were prepared from suction blister roofs. FLC stimulated T cells at lower antigen concentrations compared to unfractionated peripheral blood mononuclear cells (PBMC). CLC were more potent on a per cell basis than FLC, PBMC or adherent monocytes at presenting native gp120, native p66 or immunogenic peptides. CLC were also more efficient than FLC or PBMC in terms of the amount of antigen required for T-cell activation. Chloroquine and leupeptin inhibited presentation of intact p66, but not of an immunodominant peptide, by FLC or CLC, thus indicating that both cells utilize antigen-processing mechanisms that are based on intracellular acidification and protease activity. Incubation of CLC with monoclonal antibodies against HLA-DR, CD11b, CD18, CD50, CD54, CD58 or CD80, but not anti-major histocompatibility complex class I (MHC-I), inhibited antigen-specific T-cell proliferation to varying degrees. We conclude that human CLC retain the ability to process and present protein antigens potently to CD4+ T cells. Thus, CLC have the capacity to participate actively in the generation and maintenance of T-helper cell immunity to viral antigens during HIV-1 infection.

Antigen Presentation↗
PubMed1996

Purely cutaneous Rosai--Dorfman disease.

Cutaneous lesions of Rosai-Dorfman disease (RDD) are usually associated with nodal or other extranodal localization. We describe a female patient with RDD clinically limited to the skin. The patient presented with asymptomatic red-brown papules and nodules on the legs, arms, back, and nose. Histologically, the lesions consisted of a proliferation of large histiocytes occasionally showing emperipolesis. Histiocytes were also observed within dilated lymphatic vessels. Immunohistochemical study showed that histiocytes expressed S-100 protein and both macrophage and monocyte markers. All lesions resolved completely with Roentgen therapy. No recurrence has been observed over a 3-year follow-up period.

Adult↗