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Biomedical subjects

P Verrando

Publications and source records attributed to P Verrando.

At least 37 records · Page 2Linked to original sources
PubMed1988

Normal Merkel cells express a synaptophysin-like immunoreactivity.

Synaptophysin (SY), a specific component of the membrane of presynaptic vesicles, has been reported as a novel marker for neurons, certain neuroendocrine cells and their neoplasms including neuroendocrine carcinomas of the skin. The origin of the Merkel cells (MC) being far from clear, this study was performed to establish if normal MC express SY. It is demonstrated by immunofluorescence and immunoelectron microscopy using a monoclonal antibody SY38 to this glycoprotein that normal MC in man, rabbit and pigs express an SY-like reactivity. Although immunoblotting identification of the immunoreactive material gave negative results, it is likely that normal MC contain SY. By immunoelectron microscopy, the staining was located at the surface of cytoplasmic vesicles. In view of the possible involvement of SY in the Ca2+-dependent neurotransmitter release, the observation of an SY-like immunoreactivity in MC supports the view that they are epithelial neuroendocrine cells and that they may possess a neurosecretory function.

Animals↗
PubMed1987

Lamellar cells of sensory receptors and perineural cells of nerve endings of pig skin contain cytokeratins.

The lamellar cells of the sensory corpuscles of the pig dermis must be considered to be epithelial cells as they contain cytokeratins. The cytokeratins detected are similar to those found in simple epithelia. Moreover, lamellar cells are embedded in an extracellular matrix reminiscent of the basement membrane of epithelium since it contains laminin and collagen IV. The perineural cells surrounding the nerves of pig dermis present the same features. These results suggest that lamellar cells and perineural cells have the same origin. The nature of the lamellar and perineural cells of the rabbit or human dermis is not as clear since cytokeratins were not detected in those cells. These results, together with recent observations on Merkel cells, may indicate that epithelio-neuronal junctions are a general feature of cutaneous sensory receptors.

Animals↗
PubMed1987

Monoclonal antibody GB3, a new probe for the study of human basement membranes and hemidesmosomes.

A monoclonal antibody, GB3, has been raised against human amnion. Not only does GB3 bind to amniotic basement membrane, but it also recognizes an antigenic structure expressed by epidermal as well as by some other human basement membranes. This antigen is synthesized (and excreted) by cultured normal human epidermal keratinocytes. It is expressed to a lesser extent by the A431 epidermoid carcinoma cell line, but is not expressed by the SV40 virus-transformed SVK14 keratinocyte cell line. In ultrastructural studies, this antigen was located in the epidermal basement membrane, both in the lamina densa and in the lamina lucida, associated with hemidesmosomes. It was identified as a protein by in vitro proteolytic cleavage studies. The radio-immunoprecipitates from cultured human keratinocytes, analysed by SDS-PAGE, showed that GB3 recognized five polypeptides of 93.5, 125, 130, 146 and 150 kD under reducing conditions. They were probably linked by disulfide bonds. The tissue distribution of the antigen and the molecular weights (MWs) of its constitutive polypeptides suggest that it is different from other known components of basement membranes. It may provide a biochemical marker for hemidesmosomes. Furthermore, GB3 represents an interesting and original clinical probe, since the antigenic structure recognized by GB3 is lacking in Junctional Epidermolysis Bullosa, a lethal genodermatosis in which a dermo-epidermal splitting occurs at the level of lamina lucida.

Amnion↗
PubMed1987

Herpes gestationis factor reacts with the amniotic epithelial basement membrane.

Sera from five patients with clinically and immunopathologically proven herpes gestationis were studied by complement fixing immunofluorescence and complement fixing immuno-electron microscopy using specimens of skin, amniochorion and placenta. The results demonstrated that the complement fixation antibody (herpes gestationis factor) could bind to the basement membrane zone of skin, amnion and chorion laeve but not to that of the placental syncytiotrophoblast. These data suggest that the herpes gestationis factor may be induced by the basement membrane zone antigens of extra-villous cytotrophoblasts.

Amnion↗
PubMed1986

Identification of a 37 kilodalton protein at the epidermal basement membrane by an antiserum to human amnion.

A protein which is recognized by an antibody to human amniotic epithelial basement membrane was identified at the basal lamina of human epidermis by immunohistology. This protein was localized at the lamina lucida of human epidermal basement membrane by immunoelectron microscopy. Studies of normal human keratinocyte cultures and epidermal wound healing suggested that the protein was probably produced by keratinocytes. By immunoblotting, a basic apparent isoelectric pH (pHiapp = 7.3) protein band of 37 kD was seen. These data indicate that this 37 kD protein, clearly different from other known basement membrane components, is present in simple and stratified epithelia of ectodermal origin, and is associated with hemidesmosomes.

Amnion↗
PubMed1985

Insulin binding properties of normal and transformed human epidermal cultured keratinocytes.

Insulin binding to its receptors was studied in cultured normal and transformed (A431 line) human epidermal keratinocytes. The specific binding was a temperature-dependent, saturable process. Normal keratinocytes possess a mean value of about 80,000 receptors per cell. Fifteen hours exposure of the cells to insulin (2 X 10(-7) M) lowered their receptor number (about 65% loss in available sites); these reappeared when the hormone was removed from the culture medium ("down-regulation" process). In the A431 epidermoid carcinoma cell line, there is a net decrease in insulin binding (84% of the initial bound/free hormone ratio in comparison with normal cells) essentially related to a loss in receptor affinity for insulin. Thus, cultured human keratinocytes which express insulin receptors may be a useful tool in understanding skin pathology related to insulin disorders.

Adult↗
PubMed1985

Distribution of polyamines in human epidermis.

Consecutive sections through the epidermis were cut parallel to its surface, and the polyamine (PA) concentration in each section was measured by liquid chromatography. There was a constant decrease in PA concentration (expressed as nmol/mg DNA) from the deepest layer to the more superficial layers. Putrescine showed the greatest increase (+83%) (P less than 0.02). The elevations of spermidine and spermine levels were less marked, respectively +30% (P less than 0.05) and +27% (NS). Proliferating cells in the basal layer possess high polyamine levels and as they mature in the superficial layers their polyamine content decreases.

Female↗
PubMed1984

Response of epidermal polyamines to orally administered aromatic retinoid RO 10-9359.

Polyamine levels were measured in skin (pure epidermis) and 24-h urine before and 15 days after the start of continuous oral treatment with Etretinate (1 mg/kg/day) in 20 patients with various dermatoses. In uninvolved epidermis, treatment modified levels of spermidine (45% increase, P less than 0.05) and spermine (30% increase, P less than 0.05). In urine, the putrescine concentration was significantly altered, increasing from 1.96 to 2.60 micrograms/mg creat (P less than 0.05). During the time interval considered, variations in polyamine levels did not reflect the inhibiting mechanism of retinoids on ornithine decarboxylase, the key enzyme in the regulation of polyamine synthesis.

Adult↗
PubMed1984

Insulin receptors in cultured human keratinocytes.

Insulin binding to receptors was studied for the first time in cultured normal epidermal human keratinocytes. Binding was measured at 16 degrees C in steady-state conditions using 125I-labelled iodohormone and varying concentrations of unlabelled hormone. Insulin binding was compatible with either a two-site model--a high affinity site (about 6000 sites per cell) and a low affinity site (about 88,000 sites per cell) site--or one class of binding site with negatively co-operative interactions, or both these models may operate. Insulin receptors (IR) have been extensively studied in various biological systems, but not in epidermal cells. However, insulin resistance with defects in IR may be associated with cutaneous abnormalities (acanthosis nigricans). This led us to study insulin binding on normal human keratinocytes in culture.

Cells, Cultured↗
PubMed1983

Polyamine levels in normal human skin. A comparative study of pure epidermis, pure dermis, and suction blister fluid.

The polyamines putrescine, spermidine, and spermine were detected and measured in both free and total forms in man in pure epidermis, pure dermis, suction blister fluid, blood, and 24-h urines. The technique employed for polyamine measurement consisted in liquid chromatography by ion exchange using an automatic amino acid analyzer and a fluorescence detection system. Polyamine concentrations were found to vary significantly between the dermis and the epidermis, both quantitatively and qualitatively: spermidine and spermine levels were much higher in the epidermis than in the dermis, and putrescine&spermidine and spermidine/spermine ratios were much lower in the epidermis. These differences reflect the known differences in cellularity, proliferative activity, and differentiation between these two cutaneous regions. The high spermidine and spermine concentrations in the epidermis suggest that these substances play a special role in this tissue.

Adult↗
PubMed1983

Relative potencies of several non-steroidal anti-inflammatory drugs against soya bean 15-lipoxygenase.

The 15-lipoxygenase from soya bean has been claimed to represent a rapid assay procedure for drugs and chemical agents that inhibit other lipoxygenase products (Kingston, 1981). Although the exact role of products derived from skin lipoxygenase enzymes is not well established, many of these products, e.g. leukotriene B4, have inflammatory characteristics that warrant further examination (Camp, 1982). We have therefore started to evaluate anti-inflammatory drugs in vitro for their ability to inhibit soya bean 15-lipoxygenase, before appraising their effects in vivo in animal and human skin.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1981

Differentiation of ob 17 preadipocytes to adipocytes. Triggering effects of clofenapate and indomethacin.

Conversion of ob 17 preadipocytes to mature adipose cells is accelerated by addition of clofenapate or of indomethacin, in either the absence or presence of insulin. General stimulation of triacylglycerol-pathway enzymes is observed, as well as dramatic increase in endogenous fatty-acid synthesis. This increase is a function of drug concentration and exposure time. In contrast to indomethacin, the continuous presence of clofenapate after the cells reached confluence was required to observe the effects on adipose conversion. Growth of ob 17 fibroblasts in the presence of 5-bromo-2'-deoxyuridine normally prevents their differentiation to adipose cells. Addition of either clofenapate or indomethacin to these cells at confluence overrides this block. The effects of hypolipidemic drugs such as clofenapate observed on a long-term basis in vitro are consistent with the results of studies on adipose tissue in vivo.

Adipose Tissue↗