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Biomedical subjects

M Picardo

Publications and source records attributed to M Picardo.

At least 73 records · Page 4Linked to original sources
PubMed1995

Interaction of palladium ions with the skin.

87 subjects sensitive to both nickel sulfate and palladium-chloride pet., were contemporaneously patch retested to nickel sulfate 5% pet., metallic palladium chloride 1% pet. and to palladium chloride 1% aq. Whilst all subjects reacted to nickel sulfate and palladium chloride pet., only 3 reacted to palladium chloride aq. No positive reactions were found to metallic palladium. The negative results to palladium chloride aq. are probably due to the formation of a new palladium ion (PdCl4)2-, achieved on adding an amount of hydrocloric acid to the aqueous solution of PdCl2. The findings seem to demonstrate that the allergic reaction to palladium depends on the arrangement of the metal electrons. The sensitization to palladium does not seem to be dependent on the element itself but on the complexes formed by the different compounds. The concomitant reactions to nickel and palladium ions could be dependent on the generation of similar complexes between the ions and the skin proteins.

Dermatitis, Allergic Contact↗
PubMed1994

Direct measurement of the binding of RAS to neurofibromin using a scintillation proximity assay.

Protein-protein interactions are of major importance in many cellular processes. When no enzymic activity is involved, assays for direct binding are required. One such example is the relatively weak interaction between oncogenic Ras and the GTPase-activating protein neurofibromin (NF1). The complex between the catalytic domain of NF1 and the GTP-form of oncogenic Ras protein dissociates rapidly; hence, equilibrium binding must be quantitated. Scintillation proximity assay (SPA) technology, a radioisotopic technique that requires no separation step, was used to characterize this interaction. Leu-61 Ras complexed with [3H]GTP was generated by nucleotide exchange in the presence of a GTP-regenerating system. A SPA signal was obtained when radiolabeled Ras was mixed with NF1 fused with glutathione S-transferase (GST), anti-GST, and protein A-coated SPA beads. This signal was abolished when any of the components were omitted and also by the addition of NaCl, which potently reduces the affinity of interaction between Ras and NF1. The neutralizing anti-Ras monoclonal antibody Y13-259 and the detergent n-dodecyl maltoside, a specific inhibitor of NF1 catalytic activity, both abolished the SPA signal from the NF1/Ras assay but neither affected a control SPA signal in which a [3H]GTP.GST-Ras fusion protein was bound to protein A-coated SPA beads. This technology could be readily extended to the measurement of other protein-protein interactions and could form the basis for high-throughput screens for the discovery of novel therapeutic agents.

Escherichia coli↗
PubMed1994

Characterization of cultured nail matrix cells.

BACKGROUND: Cultures of epidermal cells are commonly used to study skin biology and differentiation. Recently a method to culture nail matrix cells has been established. OBJECTIVE: We report the biologic characteristics of nail matrix cells in vitro compared with those of epidermal keratinocytes. METHODS: Human nail matrix cells were isolated and cultured in defined medium. Electron-microscopic examination, growth rate, integrin expression and keratin synthesis pattern were evaluated. In addition, the cells were cultured in serum-containing medium. RESULTS: Nail matrix cells appear to be larger than human epidermal keratinocytes and, at the ultrastructural level, they contain a higher euchromatin/heterochromatin ratio and a lower nucleus/cytoplasm ratio and have a higher growth rate. The synthesis of "hard" keratins was detected at all calcium concentrations. Immunofluorescence analyses showed the expression of alpha 2, alpha 3, and alpha 6 integrin subunits. When cultured in serum-containing medium, nail matrix cells produced an outgrowth of epithelium and a spontaneous migration phenomenon associated with a tendency to stratify in a semilunar area that resembles the architecture of the nail matrix. The pluristratified epithelium showed characteristic markers of nail differentiation. CONCLUSION: Culture of nail matrix cells may represent a useful model to study the biologic properties of nail structure, alterations in some nail diseases and the effects of drugs.

Cell Division↗
PubMed1994

Glutathione treatment of dyspermia: effect on the lipoperoxidation process.

We recently introduced reduced glutathione into the therapeutic protocols in some selected cases of dyspermia. This therapy improved semen quality both in a pilot follow-up study and in a double-blind cross-over trial. This improvement was seen in patients with varicocele and germ-free genital tract inflammation, two pathologies in which production of reactive oxygen species or other toxic compounds could have a pathogenic role. Polyunsaturated fatty acids of phospholipids play a major role in membrane constitution and function and are one of the main targets of the lipoperoxidative process. Therefore, to understand the therapeutic action of reduced glutathione, we selected infertile patients and studied the modifications produced by the therapy in seminal parameters, biochemical sperm membrane parameters, and the pattern of fatty acids of phospholipids from blood serum and red blood cell membranes (a model widely accepted as representative of general cell membrane status). The results showed an improvement in both sperm parameters and cell membrane characteristics. This study suggests that biochemical modifications in membrane constitution could explain the seminal results of glutathione therapy. On the other hand, it seems likely that only subjects with systemic membrane disturbances associated with andrological pathologies express this membrane damage in spermatozoa, resulting in dyspermia. This sperm alteration can be partially reversed by glutathione therapy if the structural cell membrane damage is not too severe.

Adult↗
PubMed1994

Analysis of polyunsaturated fatty acids in newborn sera: a screening tool for atopic disease?

It has been demonstrated that patients with atopic disease have anomalies of fatty acid composition, as a result of altered metabolism or abnormal incorporation of fatty acids into the tissues. In the present study, in 57 newborns 'at risk' for atopic disease, the polyunsaturated fatty acid (PUFA) levels were found to be lower in cord blood in infants who subsequently developed atopic disease than in non-atopics. In all babies, levels of arachidonic acid and dihomo-gamma-linolenic acid in sera at 1 and 3 months of age were lower than those in cord blood. These changes were more marked in children who subsequently developed atopic disease, and in those who, independently of signs and/or symptoms of atopic disease, were formula-fed. A comparison between IgE and PUFA levels revealed no significant differences at any tested time interval. In conclusion, our data suggest that in children 'at risk' for atopy, PUFA levels may be predictive of atopic disease.

8,11,14-Eicosatrienoic Acid↗
PubMed1994

Expression of integrins in human nail matrix.

The aim of this study was to characterize cell-cell and cell-matrix interaction by evaluating the expression of different integrins in the nail matrix. Nail biopsies were obtained from two cadaver fingers, and eight patients with ingrowing toenails. Frozen sections were stained by indirect immunofluorescence using anti-alpha 1, anti-alpha 2, anti-alpha 3, anti-alpha 4, anti-alpha 5, anti-alpha 6, anti-alpha v, anti-beta 1, anti-beta 4 and anti-ICAM-1 monoclonal antibodies. Biopsies from normal human foreskin were evaluated as controls. alpha 1, alpha 4 and alpha 5 subunits were absent from both nail matrix and normal human skin. alpha 2, alpha 3 and beta 1 subunits were expressed in the basal and suprabasal layers of nail matrix, but only in the basal layer of skin epidermis. alpha 6 and beta 4 subunits were strongly expressed in the basement membrane zone and in the basal layer of both nail matrix and epidermis. The alpha v subunit was expressed in the basal layer of nail matrix. ICAM-1 was not expressed in nail matrix epidermis. Our findings show that despite the distinctive features of the nail apparatus, compared with the epidermis, the pattern of integrin expression is similar, although some differences in the distribution of alpha 2, alpha 3 and beta 1 subunits are detectable. These are probably related to the peculiar differentiation and keratinization of the nail.

Basement Membrane↗
PubMed1994

Serum and urine concentrations in nickel-sensitive patients after prolonged oral administration.

8 nickel-sensitive subjects were given a gradually increasing daily oral intake of NiSO4 in water. The exposure lasted from between 91 and 178 days and the total intake ranged from between 113 and 278 mg of Ni++. While 6 subjects were continuously exposed over the entire period, the other 2 were exposed for 2 shorter periods with an interval between the 2 exposures of 84 and 63 days, respectively. Nickel exposure was well tolerated by all subjects, and there was no worsening of the cutaneous manifestations. Ni++ serum and urine concentrations were repeatedly assayed. A reduction of intestinal adsorption and an activation of the renal excretion were shown through an evaluation of the ratios of Ni++ serum concentration/Ni++ cumulative oral intake, Ni++ urinary amount/nickel cumulative oral intake and Ni++ serum amount/Ni++ urine amount. The course of Ni++ faecal amounts, calculated indirectly, increased rapidly in time and was consistent with the other courses. In many subjects, the decrease in serum concentrations was followed by a slight increase. It is likely that this phenomenon is due to the release of epidermally stored nickel. These data seem to indicate that in some sensitive subjects, prolonged oral exposure to NiSO4 in water reduces the intestinal adsorption of nickel and activates its renal excretion, also promoting the mobilization of accumulated element.

Administration, Oral↗
PubMed1994

Hypertrophic allergic contact dermatitis from hair dye.

We report a case of hypertrophic allergic contact dermatitis probably due to p-phenylenediamine (PPDA) in a 26-year-old female, which developed at the sites of application of a black hair dye to the skin. Histological examination revealed an eczematous process. The lesions subsided completely except for leukoderma that remained on the leg. Patch tests showed positive reactions to PPDA, p-aminophenol and Disperse Orange 3. PPDA, which was one of the components of the dye, was considered to be the primary sensitizer because it was the only substance able to reproduce at the patch test site both the hypertrophic pattern and the permanent leukoderma found in the patient's lesions. To explain the difference in reaction between PPDA and the other 2 para-group substances, we speculate that they are due to different quantities of reactive intermediates, oxidation products and free radicals, produced by these substances.

Adult↗
PubMed1994

Antioxidant status in the blood of patients with active vitiligo.

We have previously reported that patients with active vitiligo (AVP) have elevated urinary levels of catecholamine metabolites, such as homovanillic and vanilmandelic acids, irrespective of the form of the disease (acrofacial, segmental, generalized). We have suggested that abnormal release of catecholamines from autonomic nerve endings might play an etiological role in the onset and development of vitiligo through an overproduction of toxic (oxy)radicals in the microenvironment of melanocytes in the affected areas. In the present study we have investigated whether this suggested increase in radicals might be associated with an oxidative stress in the blood of AVP. We have analyzed by gas-chromatography mass-spectrometry, by high pressure liquid chromatography, by spectrophotometry plasma levels of vitamin E (Vit E), lipoperoxides (LIP), and polyunsaturated fatty acids of phospholipids (PL-FA), erythrocyte reduced glutathione (GSH), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) activities in 62 patients affected with different forms of active vitiligo (acrofacial, segmental, generalized) and in 60 age-matched controls. Our results show that blood levels of Vit E, SOD, GSH, GSH-Px activity, LIP and PL-FA in AVP were not significantly different from those of healthy age matched controls, indicating that melanocyte damage in vitiligo is not linked with a generalized oxidative stress.

Adult↗
PubMed1994

Inter- and intra-site heterogeneity in the expression of fetal-like phenotypic characteristics by gingival fibroblasts: potential significance for wound healing.

We have previously reported that fetal and adult skin fibroblasts display distinctive migratory phenotypes on 3-D collagen substrata and that these behavioural characteristics may be quantified by a function defined as the cell density migration index (CDMI). Subsequent work indicated that this difference in migratory phenotype was due to the production by fetal fibroblasts of a migration stimulating factor (MSF) that is not produced by normal adult skin fibroblasts. We now present data indicating that: (a) unselected fibroblasts obtained from 14/14 (100%) of adult gingival explants expressed fetal-like CDMI values compared to only 1/10 (10%) of similarly explanted paired skin cells; (b) 12/12 (100%) of these gingival fibroblast lines also produced detectable quantities of MSF compared to 0/9 (0%) of the tested skin cells; (c) by microdissection studies, gingival fibroblasts obtained from different anatomical microdomains consisted of behaviourally distinct subpopulations, with cells derived from the papillary tips (PAP fibroblasts) displaying fetal-like CDMI values and persistent MSF production, whilst cells obtained from the deeper reticular tissue (RET fibroblasts) were adult-like with respect to these two criteria; (d) PAP fibroblasts were also smaller and achieved higher saturation cell densities compared to paired RET cells; (e) PAP fibroblasts passaged in vitro underwent a fetal-to-adult phenotypic transition characterized by the adoption of various RET cell characteristics, including the acquisition of CDMI values falling within the adult range and cessation in MSF production; and (f) early passage PAP fibroblasts incubated in the presence of an affinity-purified anti-MSF rabbit polyclonal antibody were induced to alter their migratory phenotype and exhibited CDMI values falling within the adult range. Statistical analysis indicated a highly significant correlation between the expression of a fetal-like CDMI and production of MSF (P < 0.00001, using the Fisher exact contingency test). Taken together, these observations suggest that the production of MSF by PAP fibroblasts is responsible for their characteristically fetal-like migratory behaviour. The existence of such inter- and intra-site phenotypic heterogeneity in populations of skin and gingival fibroblasts is discussed in the context of fibroblast lineage relationships and the possible contribution of persistently fetal-like fibroblast subpopulations to connective tissue function in wound healing.

Adult↗
PubMed1993

Saturated dicarboxylic acids as products of unsaturated fatty acid oxidation.

Upon chemical, radiation-induced or enzymatic oxidation, cis-polyunsaturated fatty acids, i.e., C18:2(n-6), C18:3(n-3), C20:2(n-6), C20:3(n-6), C20:3(n-3), C20:4(n-6), C20:5(n-3), C22:2(n-3), C22:4(n-6), C22:6(n-3), were found to generate saturated short and medium-chain length dicarboxylic acids, which can be regarded as a distinctive feature of the particular double bonds positions in the polyunsaturated fatty acid molecule. Two different dicarboxylic acids, which were unambiguously quantified by GC-MS, were produced from a single fatty acid: one deriving from the oxidative splitting at the level of the first double bond in the molecule, the other being two-carbon-atoms lower homologous. Formation of dicarboxylic acids occurred also from triacylglycerols and phospholipids containing cis-polyunsaturated fatty acids. In this case, following oxidation, the diacids remained covalently bound to the starting molecule and transesterification was necessary for identification. Being extremely stable and easily detectable compounds, dicarboxylic acids may be considered potential markers of oxidative attack to both free and esterified unsaturated fatty acids.

Animals↗
PubMed1993

Karyotype modifications in human malignant melanoma cell cultures after treatment with azelaic acid.

Azelaic acid (AzAc) is a C9 dicarboxylic acid which has recently been shown to have some therapeutic applications in skin diseases of different aetiologies. In order to study the in vitro activity of AzAc five human malignant melanoma primary cell cultures were treated for up to 60 days with 10 mM C9 2Na; the growth characteristics were defined by growth curve and the cytogenetics by Giemsa standard technique and GTG banding technique. Our data demonstrated an inhibition in replication of all five melanomas and the disappearance of the clones with chromosomal markers in four out of five melanomas after AzAc treatment.

Cell Division↗
PubMed1993

Interaction of metals in nickel-sensitive patients.

Nickel (Ni) dermatitis is thought to involve the formation of complexes between Ni ions and suitable proteins. 4 groups of 30 subjects who gave positive patch test responses to NiSO4 2.9% aq. were each retested to 1 of 4 different solutions containing equimolar (0.1 M) amounts of NiSO4 plus MgSO4, NiSO4 plus CuSO4, NiSO4 plus ZnSO4, and NiSO4 plus Li2SO4, respectively. The results, evaluated at 2 days by visual scoring only, demonstrated that the 4 metals exerted a different influence on the nickel reactions, perhaps interfering with one or more factors affecting the formation of Ni+ + complexes.

Copper↗
PubMed1992

Detection of migration stimulating activity in wound fluid.

Fetal skin fibroblasts produce a soluble "migration stimulating factor" (MSF) which is not made by their normal adult counterparts. MSF stimulates the migration of adult skin fibroblasts into 3D collagen gels, thus providing the basis of a convenient bioassay for its presence. We have previously reported that MSF stimulates hyaluronic acid (HA) synthesis by adult skin fibroblasts and that this effect on matrix deposition appears to be responsible for the observed increase in cell motility. In the present study, wound fluid samples were collected from 18 patients undergoing surgery for various nonmalignant conditions and these were then fractionated according to the protocol used to isolate MSF from fetal fibroblast-conditioned medium. Detectable levels of migration stimulating activity were present in 17/18 (94%) of these samples. Paired serum samples obtained both pre- and postoperatively from five patients with positive wound fluid samples were also analyzed for MSF activity; such activity was found in only 1/5 (20%) of the preoperative and 0/5 (0%) of the postoperative serum samples. These data suggest that the MSF present in wound fluid is not derived from a plasma transudate or from platelet degranulation, but may reflect the transient and localized reinitiation of MSF production by adult fibroblasts in response to wounding. Taken together with previous observations regarding the effect of MSF on fibroblast migration and HA synthesis, our data suggest a possible physiological function of MSF in the wound healing response. Previous studies have revealed that MSF is produced by a subpopulation of apparently persistent fetal-like skin fibroblasts obtained from breast cancer patients and is also found in the serum of these individuals. Wound fluid and serum samples were accordingly collected from patients undergoing surgery for various types of malignant conditions or with a previous history of cancer; detectable levels of MSF activity were found in 8/10 (80%) of these wound fluid samples, 2/3 (66.6%) of the preoperative, and 3/3 (100%) of the postoperative paired serum samples. These findings suggest that the presence of detectable serum levels of MSF is not restricted to breast cancer and may be a general feature of malignant disease.

Adolescent↗
PubMed1992

Paraphenylenediamine, a contact allergen, induces oxidative stress and ICAM-1 expression in human keratinocytes.

In an investigation of the role of keratinocytes in the pre-immunological phase of contact allergy, we have studied the effect of paraphenylenediamine (PPD) on cell proliferation, membrane lipid peroxidation and the expression of the intercellular adhesion molecule 1 (ICAM-1). Because PPD undergoes rapid autoxidation in the culture medium, the effect of PPD-modified medium on keratinocyte proliferation and ICAM-1 expression was also examined. PPD at low concentrations (up to 10 micrograms/ml) and with low exposure times (0.5 h) enhanced keratinocyte proliferation, but at high concentrations and with longer exposure times resulted in cell stasis and toxicity. These effects and the enhanced membrane lipid peroxidation that was also observed can be ascribed to the production of superoxide and hydrogen peroxide by the autoxidation of PPD in the medium. At non-cytotoxic concentrations, PPD induced ICAM-1 expression on the keratinocytes. PPD-modified medium was also cytotoxic to the keratinocytes and induced ICAM-1 expression in non-cytotoxic concentrations. It appeared that superoxide and hydrogen peroxide were not responsible for the cytotoxicity. These results are consistent with the view that oxidative stress may be an essential part of the pre-immunological phase in the induction of allergic contact dermatitis.

Allergens↗