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Biomedical subjects

A Marconi

Publications and source records attributed to A Marconi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Peak velocity of the outflow tract of the aorta: correlations with acid base status and oxygenation of the growth-retarded fetus.

OBJECTIVE: To correlate the peak velocities of the aortic outflow tract of growth-retarded fetuses with fetal acid base status and oxygenation measured in utero. METHODS: Thirty-one growth-retarded fetuses with abnormal umbilical pulsatility index (PI) measurements underwent fetal blood sampling. Blood pH, carbon dioxide pressure (PCO2), oxygen pressure (PO2), oxygen saturation, lactate concentration, and hemoglobin concentration were measured. Using color Doppler equipment, we measured the peak velocities of the outflow tract of the aorta, pulmonary artery, and ductus arteriosus before fetal blood sampling. RESULTS: The peak velocities measured in the outflow tract of the aorta, pulmonary artery, and ductus were significantly lower in growth-retarded fetuses than in 140 normal fetuses of comparable weight. The correlation observed between pulmonic and aortic peak velocities was significant (r = 0.84), as was that between pulmonic and ductal peak velocities (r = 0.74). Growth-retarded fetuses with abnormal aortic peak velocities had significantly lower values of PO2, oxygen content and pH, and had higher lactate concentration and PCO2 than did growth-retarded fetuses with normal peak velocities. Estimated fetal weight and umbilical PI (mean +/- standard deviation) were not significantly different in these two groups. Moreover, significant direct correlations were found between proximal aortic peak velocities and lactate concentrations (correlation coefficient 0.71, P < .0001) and O2 content (P < .02, r = 0.42). CONCLUSION: For growth-retarded fetuses, Doppler peak velocity in these vessels is significantly lower than in normal fetuses of comparable weight. Aortic, pulmonic, and ductal peak velocity correlated significantly. Growth-retarded fetuses with abnormally low peak velocity in the outflow tract of the aorta have a higher risk of acidemia and hypoxia than those with normal velocities.

Aorta↗
PubMed1995

Transforming growth factor-beta 1 modulates beta 1 and beta 5 integrin receptors and induces the de novo expression of the alpha v beta 6 heterodimer in normal human keratinocytes: implications for wound healing.

The molecular mechanism underlying the promotion of wound healing by TGF-beta 1 is incompletely understood. We report that TGF-beta 1 regulates the regenerative/migratory phenotype of normal human keratinocytes by modulating their integrin receptor repertoire. In growing keratinocyte colonies but not in fully stratified cultured epidermis, TGF-beta 1: (a) strongly upregulates the expression of the fibronectin receptor alpha 5 beta 1, the vitronectin receptor alpha v beta 5, and the collagen receptor alpha 2 beta 1 by differentially modulating the synthesis of their alpha and beta subunits; (b) downregulates the multifunctional alpha 3 beta 1 heterodimer; (c) induces the de novo expression and surface exposure of the alpha v beta 6 fibronectin receptor; (d) stimulates keratinocyte migration toward fibronectin and vitronectin; (e) induces a marked perturbation of the general mechanism of polarized domain sorting of both beta 1 and beta 4 dimers; and (f) causes a pericellular redistribution of alpha v beta 5. These data suggest that alpha 5 beta 1, alpha v beta 6, and alpha v beta 5, not routinely used by keratinocytes resting on an intact basement membrane, act as "emergency" receptors, and uncover at least one of the molecular mechanisms responsible for the peculiar integrin expression in healing human wounds. Indeed, TGF-beta 1 reproduces the integrin expression pattern of keratinocytes located at the injury site, particularly of cells in the migrating epithelial tongue at the leading edge of the wound. Since these keratinocytes are inhibited in their proliferative capacity, these data might account for the apparent paradox of a TGF-beta 1-dependent stimulation of epidermal wound healing associated with a growth inhibitory effect on epithelial cells.

3T3 Cells↗
PubMed1995

In vitro infection of human epidermal Langerhans' cells with HIV-1.

Epidermal Langerhans' cells (LC) from human immunodeficiency virus type-1 (HIV-1)-infected patients harbour HIV-1 proviral DNA and RNA. In the present study, we investigated whether LC from epidermis of normal, HIV-seronegative subjects could be infected in vitro with HIV-1. Epidermal cells (EC) spontaneously detached from epidermal sheet cultures were enriched for LC (10-25% of CD1a+/CD4+ cells), deprived of contaminating T cells and then incubated with HIV-1IIIB. After 24 hr, purified LC and LC-depleted EC fractions were obtained by immunomagnetic separation. Polymerase chain reaction (PCR) analysis showed the presence of HIV-1 proviral DNA (gag) only in purified LC. In addition, LC-enriched EC, purified LC, LC-depleted EC or the non-permissive cell line, TF-1, the latter having being previously challenged with HIV-1IIIB for the same length of time as the EC, were co-cultivated with C8166 cells, and the co-cultures assessed for the presence of HIV DNA by PCR. Co-cultures of C8166 cells with purified LC or LC-enriched EC previously exposed to HIV-1IIIB exhibited a time-dependent increase in HIV proviral DNA. In contrast, PCR analysis of C8166 cells co-cultured with either LC-depleted EC or TF-1 cells gave negative results. Finally, C8166 cells co-cultured with HIV-infected LC formed syncytia, showed membrane budding and released numerous retroviral particles. The results indicate that LC from normal subjects can be infected in vitro with HIV and can transmit infection to myeloid cells. This in vitro model may help in understanding the regulation of HIV infection of LC.

Cell Movement↗
PubMed1994

Spatial discontinuities in human immunodeficiency virus type 1 quasispecies derived from epidermal Langerhans cells of a patient with AIDS and evidence for double infection.

A nonhomogeneous spatial distribution of human immunodeficiency virus type 1 quasispecies was observed for epidermal Langerhans cells purified from skin patches taken from a patient with AIDS soon after death. Each patch presented a unique collection of sequences, distinct from those of juxtaposed patches or those derived from the other leg. Infection of Langerhans cells by virus from underlying T cells in the dermis might explain this partition. The analysis revealed the presence of two distinct cocirculating viral strains, indicating double infection.

Acquired Immunodeficiency Syndrome↗
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

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

Short courses of intravenous clodronate in the treatment of Paget's disease of bone: a long-term follow-up trial.

The effect of short-term treatment with intravenous clodronate (300 mg daily for 10 days) was assessed in 12 patients with active Paget's disease of bone. The treatment was found to be associated with a marked reduction in serum alkaline phosphatase levels, from 330 U/l +/- 247 (S.D.) at baseline to 225 +/- 86 on day 11. These levels decreased further during the subsequent 2 months, to stabilize thereafter within the normal range (30-100 U/l)during the entire 1-year follow-up period. No changes were observed in serum calcium and phosphorus levels, whereas serum parathyroid hormone increased significantly on day 11. It is concluded that short-term i.v. treatment with clodronate provides an effective alternative to oral treatment and achieves complete remission of Paget's disease for at least 1 year.

Aged↗
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↗
PubMed1991

Study of the count-to-mass conversion factor for asbestos fibres in samples collected at the emissions of three industrial plants.

Count-to-mass conversion factors for asbestos fibres in the stack emissions of three industrial plants were calculated. Dust samples deriving from different working processes were collected downstream from the fabric-based filtration systems. Gravimetric measurements were carried out utilizing an X-ray diffraction procedure based on the use of a silver filter that permits the correction for X-ray absorption by the sample. The number of fibres covered by regulations ('Regulated fibres') (F) was counted by phase-contrast optical microscopy (PCOM) on a section of the same filter as had been used for gravimetric measurements. The values of the conversion factors vary widely, ranging from 0.4 x 10(3) to 4.9 x 10(3) fibers per microgram (F microgram -1) according to the working process involved. They are always less than 20 x 10(3) F microgram -1, the value specified in the EEC Directive 217/87 concerning the prevention of asbestos pollution in the environment.

Air Pollutants, Occupational↗
PubMed1991

Detection of HIV-1 in epidermal Langerhans cells of HIV-infected patients using the polymerase chain reaction.

Langerhans cells (LC) are bone marrow-derived, HLA-DR+, CD1a+, dendritic antigen-presenting cells found in stratified squamous epithelia. Within resident epidermal cells (EC), LC are the only cells expressing the CD4 antigen and are, therefore, a possible target for human immunodeficiency virus (HIV) infection. To date, conflicting results have been reported on the in vivo infection of LC by HIV. The aim of the present study was to investigate the presence of HIV-1 proviral DNA in epidermal LC of HIV-1-infected patients. EC suspensions were prepared from clinically normal skin of nine seropositive patients. Purified LC and LC-depleted EC were obtained by immunomagnetic separation and analyzed for the presence of HIV-1 proviral DNA by the polymerase chain reaction using primer pairs from different conserved regions (env and gag) of the HIV-1 genome. HIV-1 proviral DNA was detected in LC from seven of nine patients. LC-depleted EC fractions from the same nine patients were all negative, with the exception of one case. Altogether these results demonstrate that epidermal LC are infected by HIV-1 and constitute the only resident cell type in the epidermis harboring the virus. Further studies are, however, needed to demonstrate HIV replication in LC and to elucidate the functional role of LC in this infection.

Adult↗
PubMed1989

Airborne mineral fibre concentrations in an urban area near an asbestos-cement plant.

Ambient air concentrations of asbestos and total mineral fibres were measured during the period June-July 1985 at several locations near a large asbestos-cement factory located in the proximity of a northern Italian town. Measurements of the number and type of fibres were made by means of analytical scanning electron microscopy and energy-dispersive X-ray analysis (SEM-EDXA), essentially according to the RTM2 reference method of the Asbestos International Association. Total mineral fibre concentrations (longer than 5 microns) ranged from below detection limit (D.L., i.e. 0.4 fibres per litre (f/1] to 227 f/1 (single value); mean values ranged from 1.3 to 74.0 f/1. However, elemental microanalysis (EDXA) showed that about 65% of fibres were sulfate fibres, 20% were aluminium silicates or other silicates, and only 15% were asbestos fibres (mainly chrysotile and tremolite-group amphiboles). Asbestos concentrations (fibres more than 5 microns in length) were in the range of less than D.L. to 19.1 f/1, mean values ranging from less than D.L. to 11.1 f/1. The results obtained showed large differences in day-to-day concentrations, suggesting that they were affected by the rate of production in the plant and by weather conditions. In particular, wind direction and distance from the source appeared to be of major importance since the highest asbestos fibre concentrations were mostly found at points closer to the source and downwind. When the distance from the source was increased, other local factors appeared to be determining. In addition, the large proportion of non-asbestos mineral fibres and elongated sulfate (or sulfur-containing) particles clearly indicates major contributions from other sources, such as local pollution and natural soil erosion.

Air Pollutants↗