Biomedical subjects

A Giannetti

Publications and source records attributed to A Giannetti.

At least 73 records · Page 4Linked to original sources

PubMed1994

Quantitation by competitive PCR of HIV-1 proviral DNA in epidermal Langerhans cells of HIV-infected patients.

Langerhans cells (LC) belong to the dendritic cell family and represent the principal antigen presenting cells populating squamous epithelia. We have reported the presence of human immunodeficiency virus Type 1 (HIV-1) proviral DNA and RNA in purified LC from the epidermis of seropositive patients. The aim of this study was to quantify HIV-1 proviral DNA in LC of infected patients using a competitive polymerase chain reaction (PCR) assay. Bulk epidermal cell (EC) suspensions were obtained from the skin of nine AIDS patients and six seronegative subjects. Purified LC and LC-depleted EC were prepared by immunomagnetic separation using an anti-CD1a monoclonal antibody. LC preparations did not contain T cells, as assessed by reverse transcription PCR analysis of the T cell receptor beta-chain gene (C region). In addition, no CD14+ cells could be detected in LC fractions by immunostaining of cytospin preparations. To quantify HIV-1 DNA, a new competitive PCR system was devised using SK145/150 as primers (gag) and a competitor plasmid DNA with a modified sequence (209 instead of 142 bp). The number of HIV-1 DNA copies found in the LC of AIDS patients ranged from 107 to 3,645/10(5) LC. In contrast, LC-depleted EC from the same subjects were all negative. The results indicate that in AIDS patients the frequency of infected LC is comparable to that reported for peripheral blood CD4+ T cells.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Phosphatidylserine enhances the ability of epidermal Langerhans cells to induce contact hypersensitivity.

Phosphatidylserine (PS) modulates several immune functions in vitro, including T cell activation, antibody and cytokine production, and macrophage growth. In the present work we studied the effects of PS on the induction of contact hypersensitivity (CH) in mice. BALB/c mice painted with PS (9.4-75 mg/kg) and with a sensitizing dose of DNFB or oxazolone on the same skin site exhibited a dose-dependent augmentation of CH reactions to either DNFB (> 60%) or oxazolone (> 35%), respectively. Bovine brain PS-enriched phospholipid mixture, lyso-PS, and dipalmitoyl-PS also induced similar enhanced CH responses, whereas phosphatidylglycerols had no effect. Increased CH was observed only when PS was applied from 2 days before to 12 h after DNFB. Immunization of naive syngeneic mice with skin grafts that were treated with PS and DNFB also led to enhanced (> 50%) CH responses. In addition, immunization by iv injection of epidermal cell suspensions enriched for Langerhans cells (LC) or of purified LC that were treated with PS (1-100 microM, 30 min, 37 degrees C), and then modified in vitro with DNBS (1 mg/ml, 30 min, 37 degrees C) led to increased (> 30-75%) CH responses in recipient syngeneic animals. Finally, adoptive transfer of DNFB-immune lymph node cells obtained from mice that were treated with PS induced augmented CH responses in recipient animals. The results suggest that PS is capable of up-regulating the induction of CH in mice by stimulating the APC function of epidermal LC.

Animals↗

PubMed1993

Free radical production during metabolism of organic hydroperoxides by normal human keratinocytes.

Evidence of a relationship between tumor production induced by various organic (hydro)peroxides and free radical formation has been shown in cultured murine keratinocytes and human skin-tumor cell line. In the present study the bioactivation of cumene hydroperoxide, t-butyl-hydroperoxide, and benzoyl peroxide via one-electron oxidation or reduction was compared in freshly isolated and in cultured normal human keratinocytes. The formation of methyl free radicals during the metabolism of cumene and t-butyl-hydroperoxide was shown by the electron spin resonance-spin trapping technique. Radical formation increased under hypoxic conditions. An intracellular activation site was demonstrated by the use of two spin-trapping agents, the hydrophilic, membrane-impermeable, 3,5-dibromo-4-nitrosobenzenesulfonic acid and the lipophilic, membrane-permeable alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone. At 30 min incubation and 25 mM concentration, hydroperoxides exhibited cytotoxicity, as indicated by trypan blue exclusion and lactate dehydrogenase release assay; free radicals were concurrently trapped. Hydroperoxides at a lower concentration (1 mM) did not significantly affect cell viability. However, free radical production was still detected using a membrane-permeable spin trap. The incubation of keratinocytes with benzoyl peroxide did not show any peroxide-dependent radical adduct. No significant differences in bioactivation capability were demonstrated between freshly isolated and cultured human keratinocytes. The results indicate that cultured human keratinocytes can be used as a model system for the study of the metabolic activation to free radical intermediates of toxic and carcinogenic compounds in the epidermis.

Benzene Derivatives↗

PubMed1993

Autoradiographic detection of substance P receptors in normal and psoriatic skin.

Substance P has been detected in human skin and has been implicated in the pathogenesis of certain inflammatory cutaneous disorders. However, little is known about the number and distribution of substance P binding sites in the skin. Receptor autoradiography was employed to detect and quantitate substance P receptors in normal as well as psoriatic skin. Substance P binding sites were distributed in the epidermis and dermis both in normal and psoriatic skin. In the dermis, the highest densities of SP binding sites were found in the areas corresponding to the dermal papillae and the adnexal structures. Quantitative analysis revealed that saturable binding was obtained both in the epidermis and in the labeled dermal areas. Rosenthal plot values were consistent with a single population of binding sites. No difference in the binding measurements was observed between normal and psoriatic skin. The presence of substance P receptors in the epidermis and in the dermal papillae raises interesting issues on the possible targets of this peptide in human skin both under physiologic and pathologic conditions.

Autoradiography↗

PubMed1993

Distinctive integrin expression in the newly forming epidermis during wound healing in humans.

The integrin receptor family plays a fundamental role in mediating cell attachment to a variety of extracellular matrix molecules. In normal human epidermis, the alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 4, and alpha v beta 5 integrin heterodimers are expressed and appear largely confined to the basal cell layer. In the present study, beta 1, beta 4, and alpha v integrin expression in the epidermis during wound healing in humans was examined. Punch biopsies were performed on healthy volunteers. At daily intervals up to day 8, and at days 11, 14, 21, and 28, the wound site was surgically removed. Using immunofluorescence microscopy, several modifications of the integrin expression pattern were observed on migrating keratinocytes during the re-epithelialization phase of the wound-healing process: i) alpha v expression was strongly enhanced and polarized at the basal pole of basal keratinocytes; ii) among the beta 1 integrins, alpha 3 beta 1 was overexpressed and distributed over the entire basal keratinocyte membrane and a weak alpha 5 beta 1 reactivity became evident; and iii) alpha 6 beta 4 was detected as a linear staining along the newly forming dermal-epidermal junction. Moreover, both during the re-epithelialization phase and during the first 2 weeks after wound closure, alpha 3, alpha 6, alpha v, beta 1, and beta 4 were no longer confined to the basal layer, as in normal epidermis, but were also found on several suprabasal cell layers. These results suggest that alpha v beta 5, alpha 3 beta 1, and alpha 5 beta 1 may be the main integrin receptors mediating keratinocyte spreading and migration over the provisional matrix of the wound bed.

Adult↗

PubMed1993

Epidermal Langerhans cells are resistant to the permeabilizing effects of extracellular ATP: in vitro evidence supporting a protective role of membrane ATPase.

Extracellular adenosine 5'-triphosphate (ATPo) can induce pore formation in cell membranes, leading to cell permeabilization and eventual cell death. In this study, we examined the sensitivity of human epidermal Langerhans cells to ATP-induced permeabilization and tested the possibility that the Mg(++)- or Ca(++)-dependent plasma membrane ectonucleotidase (mATPase) on Langerhans cells provides protection against the cytotoxic effects of ATPo. Membrane permeability was assessed by using the fluorescent tracer propidium iodide, which confers red nuclear fluorescence to permeabilized cells. Langerhans cells were identified within human epidermal cell suspensions with fluorescein isothiocyanate-conjugated MoAb against CD1a or human leukocyte antigen-DR (HLA-DR) antigens. Cultured human keratinocytes and J774 macrophages were both highly sensitive to permeabilization induced by incubation with ATP (0.5 to 20 mM at 37 degrees C), whereas Langerhans cells were relatively resistant. The non-hydrolyzable ATP analog, adenosine 5'-(beta,gamma-imido) triphosphate, but not other nucleotides such as ADP, AMP, GTP, or UTP, was also able to induce permeabilization comparable to that of ATP, thereby suggesting that ATP hydrolysis is not required for this effect. ATP4- is the moiety most likely responsible for permeabilization, because propidium iodide uptake occurred only when the pH of the medium was > or = 7.4. Permeabilization induced by ATP was augmented by chelation of divalent cations with ethylene-diamine-tetraacetic acid and by the addition of lanthanum or cerium (0.01 to 1 mM). Finally, incubation with the adenosine analog, 5'-p-fluorosulfonylbenzoyl-adenosine (1 mM), inhibited mATPase staining of Langerhans cells in human epidermal sheets, but markedly augmented ATP-induced permeabilization of Langerhans cells. The results indicate that epidermal LC are resistant to the lytic effects of ATPo and that mATPase is involved in such resistance.

Adenosine Triphosphatases↗

PubMed1993

Congenital dermatofibrosarcoma protuberans.

Congenital dermatofibrosarcoma protuberans occurred in a 16-year-old girl. The lesion was a hard cutaneous plaque on the abdomen. It was present at birth and slowly enlarged during the patient's lifetime. Histologic examination was essential to establish the diagnosis and to differentiate it from other congenital fibrohistiocytic proliferations.

Abdomen↗

PubMed1993

Assessment of topical corticosteroid activity on experimentally induced contact dermatitis: echographic evaluation with binary transformation and image analysis.

A new echographic evaluation method employing a B scanner and a dedicated software (Dermavision 2D, Cortex Technology, Hadsund, Denmark) was used in assessing the potency of three different corticosteroids. Experimental lesions were induced by patch tests with nickel sulfate 5% in petrolatum in 10 sensitized subjects and treated with two medications of different steroids (clobetasol propionate, fluocinolone acetonide or clobetasone butyrate) performed 16 and 40 h after the application of the nickel patch tests. Clinical and echographic evaluations were carried out at the beginning of the experiment and 64 h after the induction of the reactions. After obtaining echographic images, these were processed by software, enabling the selection of amplitudes of interest, the highlighting of parts of images and their assessment by a value corresponding to the number of pixels (picture elements). For evaluations a low reflecting band was chosen, marking edema and inflammatory infiltration. At positive patch test sites we observed a progressive increase in the number of low reflecting pixels, in accordance with the intensity of the reaction. Therapeutic response was assessed as the difference between values of treated and untreated test sites. The rank order of the efficacy of test substances as determined echographically was identical to the rank order generally accepted for these steroids. This evaluation method of topical corticosteroid activity could be usefully employed besides traditional evaluation methods.

Administration, Topical↗

PubMed1993

Neuropeptides and skin inflammation.

Neuropeptides (NP) are protein compounds contained both in the central and peripheral nervous system. They can be antidromically released from sensory nerves and are implicated in the so-called neurogenic inflammation. They also exert a number of functions within the immune system and are thought to act as trophic as well as mitogenic substances. Several NP have been detected in human skin by immunohistochemical and radioimmunological techniques, and recent reports have demonstrated that NP could be involved in the mechanisms of certain dermatoses. The involvement of NP in either physiological or pathophysiological skin conditions is discussed. Moreover, a few questions, which still need to be addressed, are raised, and future directions this field of research should take are outlined.

Calcitonin Gene-Related Peptide↗

PubMed1993

Comparative study of the efficacy and safety of loratadine syrup and terfenadine suspension in the treatment of chronic allergic skin diseases in a pediatric population.

The safety and efficacy of loratadine (Sch 29851, CAS 79794-75-5) syrup (5 or 10 mg QD) was compared to terfenadine (CAS 50679-08-8) suspension (30 mg b.i.d.) in a randomized, third party blind, parallel-group, multicenter trial. Two hundred thirty-six children ages 6-12 years, with chronic allergic skin disorders were treated for 14 days. The predominant skin condition was atrophic dermatitis (88% of the efficacy population). Evaluation of efficacy was based on investigator and patient assessment of symptoms, overall condition of the disease, and therapeutic response to treatment. After 7 and 14 days of treatment, and in the endpoint analysis (last valid study visit for all patients) the decreases from baseline in mean total sign/symptom scores, and all individual symptoms, did not differ significantly (p > 0.05) between treatments. Itching improved 54% in the loratadine group and 58% in the terfenadine group in the endpoint analysis. Forty-five percent of patients treated with loratadine and 46% of terfenadine-treated patients treated had complete or marked relief of their symptoms at endpoint. The efficacy of loratadine increased during the study, suggesting that patients did not develop tolerance to the medication over the 14-day course of therapy. Mild to moderate treatment-related adverse experiences were reported in 7/113 patients (6%) treated with loratadine and 11/119 patients (9%) treated with terfenadine. Single daily doses of 5 mg or 10 mg loratadine syrup were comparable to terfenadine suspension 30 mg twice daily for improving the symptoms of chronic allergic skin disorders in children. Loratadine was safe and well tolerated.

Child↗

PubMed1993

Direct detection of HIV-1 RNA in epidermal Langerhans cells of HIV-infected patients.

Human Langerhans cells (LC) are bone marrow-derived, HLA-DR+, CD1a+, and CD4+ dendritic antigen-presenting cells found in stratified squamous epithelia. As other members of the dendritic leukocyte family, to which they belong, LC have been reported as targets for HIV-1 infection. The aim of the present study was to investigate whether HIV-1 RNA is expressed in epidermal LC of HIV-1-infected patients. Bulk epidermal cell (EC) suspensions were prepared from skin of nine recently deceased AIDS patients and 11 seronegative controls. Purified LC (94 +/- 4% HLA-DR+ cells with no CD3+ cells, as assessed by flow microfluorimetry analysis) and LC-depleted EC were obtained by immunomagnetic separation using an anti-CD1a monoclonal antibody. Samples were analyzed for the presence of HIV-1 RNA by reverse transcription of a spliced mRNA region of the tat gene, followed by polymerase chain reaction amplification. HIV-1-spliced RNA was detected in LC from 6 of 9 patients examined, whereas LC-depleted EC fractions from the same patients were all negative. The results indicate that epidermal LC from HIV-seropositive patients actively transcribe HIV-1 proviral DNA, further supporting the hypothesis that HIV productively infected LC could serve as a reservoir of the virus in the epidermis and as a source for the infection of T lymphocytes.

Adult↗

PubMed1993

Cervical nucleolysis: indications, technique, results. 190 patients.

For many years now percutaneous techniques have proved effective in the curative treatment of lumbar disc herniation, mostly in young subjects. This technique, however, is seldom indicated, let alone performed, in the cervical spine for a variety of reasons: a) the neck contains several closely arranged structures such as the vasculo-nervous bundles, the airway-digestive tract and the cervical spine around the spinal cord; b) the disc is approached by the anterior route, in contrast with the lumbo-sacral spine where the approach is posterolateral; c) the manufacturers insist on restrictions in the use of chymopapain in view of the potential risk of spinal cord damage, either by possible breaks in the meninges of by accidental diffusion of the enzyme into perimedullary epidural structures which support a particularly developed venous plexus; d) legal protection may be denied to operators who perform cervical chemonucleolysis, since the product has not yet been officially authorized, in France and perhaps elsewhere*, for treatment of cervical disc herniation. Several years of experience in the practice of cervical nucleolysis have convinced the authors that this method is remarkably effective and can be used in the treatment of cervicobrachial neuralgia (CBN) occurring in young subjects. Radiculalgia is essentially due to a disc fragment being positioned within the vertebral canal or a foramen, thereby compressing the nerve roots. During several years microsurgery of the disc has been effective in the treatment of refractory radiculalgia, and to compete with this procedure familiar to neurosurgeons cervical nucleolysis must convincingly demonstrate that its therapeutic value is at least as good as that of surgery. Finally, the vast majority of cervical disc herniations is made up of free disc fragments located within the meshes of the posterior longitudinal ligament of the spine (transligamentous fragment). Cervical nucleolysis was introduced in France by Bonafe and Lazorthes made enthusiastic by their first studies, and the idea of this procedure, developed by a radio-neurosurgical team, has gradually been gaining ground. The decision to intervene is made when the radiculalgia is recurrent or resistant to a well-conducted medical treatment of several weeks duration. Therefore all disc herniations that would have been treated surgically can be treated by injection of an enzyme. This point is very important, and in fact the well-codified and effective surgical procedure has progressively been abandoned by the operators, in view of the simplicity of nucleolysis and the rapid pain relief it procures.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

Multinucleate cell angiohistiocytoma.

We report a case of multinucleate cell angiohistiocytoma occurring in a 50-year-old woman and presenting with a 4-year history of asymptomatic red papules on the face. Histologically, there was a dermal vascular proliferation associated with numerous multinucleate cells. Immunohistochemical studies showed vascular spaces surrounded with mature vascular endothelial cells, and the presence of numerous interstitial factor XIIIa+ cells. Multinucleate cells exhibited intermediate filaments of the vimentin type, but were not stained by endothelial cell or macrophage markers, and were factor XIIIa-. This condition must be addressed in the differential diagnosis of other skin vascular proliferations, such as Kaposi's sarcoma and angiofibromas.

CD4-Positive T-Lymphocytes↗

PubMed1992

Substance P is diminished and vasoactive intestinal peptide is augmented in psoriatic lesions and these peptides exert disparate effects on the proliferation of cultured human keratinocytes.

An involvement of neurogenic components in the pathogenesis of psoriatic lesions has been suggested and neuropeptides are thought to play a modulatory role in cutaneous inflammation. In this study, we evaluated the immunoreactivity of the neuropeptides vasoactive intestinal polypeptide (VIP) and substance P (SP) in the skin of patients with chronic plaque psoriasis, by immunohistochemistry and radioimmunoassay. No differences were observed, by immunohistochemistry, in the expression and localization of VIP and SP between psoriatic and normal skin. Using the radioimmunologic technique on whole skin homogenates, VIP levels were significantly increased in psoriatic lesions as compared to normal skin. By contrast, SP levels were significantly lower in lesional and non-lesional psoriatic skin than in normal skin. In addition, we examined the effect of VIP and SP on the proliferation of cultured normal human keratinocytes. VIP (1-28) (1 nM-1 microM) as well as VIP fragments (10-28) (1 nM-1 microM) and (22-28) (1 nM-1 microM) stimulated the proliferation of keratinocytes in a dose-dependent manner, whereas the VIP fragment (1-12) (1 nM-1 microM) was ineffective. The VIP antagonist (N-Ac-Tyr1, D-Phe2)-GRF (1-29)-NH2 (0.1 microM) significantly inhibited the VIP effect on keratinocytes. On the other hand, SP (0.1 microM) not only failed to stimulate keratinocyte growth, but also blocked the VIP-induced stimulation of these cells. The imbalance of cutaneous VIP and SP and their disparate effects on the proliferation of normal human keratinocytes in culture would suggest that these peptides are involved in the pathogenesis of psoriasis and may exert different modulatory activities in the mechanisms underlying the psoriatic lesion.

Cell Division↗

PubMed1992

Membrane ecto-ATPase on epidermal Langerhans cells.

Epidermal Langerhans cells (LC) possess a plasma membrane Mg(++)- or Ca(++)-dependent ecto-ATPase (mATPase), the function of which is not known. On the other hand, extracellular ATP (ATPo) has been shown to cause a rapid increase in cell-membrane permeability for selected cells, thus inducing the entry of exogenous substances, leading eventually to cell death. ATPo has also been shown to be a mediator of T cell-mediated cytotoxicity. We have observed human LC to be resistant to the permeabilizing effects of ATPo when compared to cultured human keratinocytes and J774 macrophages. In addition, our preliminary evidence in vitro suggests that mATPase on LC may provide protection against the lytic effects of ATPo. Finally, we propose that this latter mechanism may also operate in vivo.

Adenosine Triphosphatases↗

PubMed1992

Alpha-6 (CD 49f) integrin expression in genetic and acquired bullous skin diseases. A comparison of its distribution with bullous pemphigoid antigen.

Bullous pemphigoid (BP) antigen and alpha 6 integrin are hemidesmosome-associated glycoproteins of basal keratinocytes. In this work, the immunoreactivity of antibodies to BP and to alpha 6 in salt- or dispase-split human skin, and in 46 biopsy specimens of various genetic and autoimmune bullous dermatoses taken from various body sites, was studied by double-labeling immunofluorescence. In all specimens, both antigens localized at the same side of the blisters observed, i.e. the roof of the bulla in cases with a junctional or dermolytic cleavage, or the floor of the blister in those with intraepidermal cleavage. Immunostaining for alpha 6 was strong and present in all specimens studied, whereas the one obtained with the BP serum was absent from some specimens. These results show that the BP antigen and the alpha 6 integrin colocalize at the level of cleavage in bullous diseases; however, the more consistent and reproducible reactivity obtained with the anti-alpha 6 antibody suggests that this should be preferentially used in the immunohistochemical investigation of bullous dermatoses.

Antigens, Surface↗

PubMed1992

Epidermal Langerhans cells after allogeneic bone marrow transplantation: depletion by chemotherapy conditioning regimen alone.

Depletion of Langerhans cells (LC) is known to follow bone marrow transplantation (BMT) and is thought to be mainly related to pretransplant radiation and chemotherapy conditioning regimens. We studied sequential biopsies of clinically normal skin of 22 thalassemic and leukemic patients undergoing allogeneic BMT who had received only chemotherapy (busulfan and cyclophosphamide) as conditioning regimen. LC were identified immunohistochemically using antibodies against CD1a and HLA-DR antigens, and their number expressed per square mm of epidermal vertical section, the latter measured by computerized image analysis. After the preparatory regimen, the number of LC decreased progressively in both leukemic and thalassemic patients. CD1a+ and HLA-DR+ epidermal cells were reduced, respectively, to 68.5% and 64.5% of their original number around Day 2, and to 23.1% and to 18.2% around Day 17. By this time, electron microscopic examination of selected biopsies confirmed the depletion of LC. Variable repopulation was observed between Days 40 and 60. Our results indicate that a conditioning regimen based exclusively on high dose chemotherapy depletes epidermal LC early after BMT, and that such depletion is not related to the development of acute graft-versus-host disease.

Adolescent↗

PubMed1992

B-scanning evaluation with image analysis of psoriatic skin.

Ten psoriatic plaques from different subjects were investigated by 20 MHz ultrasound B scanning. Lesions were evaluated before therapy, and after 7 and 15 days of topical treatment with anthralin. Recordings from lesional skin were compared with those from clinically non-involved contralateral skin. Images were assessed by means of a new image analysis program, allowing the conversion of the B-scan image color scale into a numerical amplitude scale, the selection and highlighting of amplitude bands, and the quantification of objects reflecting in a definite amplitude range. B-scanning evaluation of the psoriatic plaque revealed a thickening of the epidermis and dermis, the presence of parallel acoustic shadows in the dermis, and a characteristic hypo-echogenic band corresponding to the papillary dermis. Image processing allowed an exact quantification of the progressive reduction in thickness of the epidermis and dermis and of the hypo-echogenic band observed at skin sites which had been treated with topical substances. Thus, the echographic method with image analysis allows the evaluation of three different parameters of response to topical treatment of psoriatic skin.

Adult↗