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Biomedical subjects

L Frati

Publications and source records attributed to L Frati.

At least 145 records · Page 8Linked to original sources
PubMed1995

Expression of steroid receptors in acoustic neuroma.

The expression of steroid receptors has been investigated in an attempt to clarify the role of steroid hormones in the proliferation and progression of acoustic neuromas. Specimens of tumours taken during translabyrinthine surgery were tested for cytosolic (c) and nuclear (n) steroid receptors. Oestrogen and progesterone receptor levels were evaluated by enzymatic immuno-assay, while androgen receptor binding levels were detected by dextran-coated charcoal method in a single-step determination. In some cases, the six point Scatchard analysis of cytosolic and nuclear androgen receptor was also performed. Threshold values were: 3 fmol/mg of proteins for cytosolic steroid receptors and 20 fmol/mg DNA for nuclear steroids, which corresponded to approximate median values of cytosolic and nuclear oestrogen and progesterone, respectively. Oestrogen and progesterone appeared to be localized more frequently in the nuclei rather than in the cytosol (70% oestrogen and progesterone positivity in the nuclei; 30% oestrogen, 40% progesterone positivity in the cytosol), while androgen receptors were preferentially localized in the cytosol (80% positivity in the cytosol; 40% positivity in the nuclei). A negative non-linear correlation between cytosolic oestrogen and cytosolic androgen receptors was found. There was a direct linear correlation between cytosolic oestrogen and nuclear oestrogen levels. A strict correlation between nuclear oestrogen and nuclear progesterone incidence was shown. Preliminary analysis of clinical data and biochemical parameters showed that cytosolic progesterone levels inversely correlated with tumour size.

Aged↗
PubMed1995

Monosialoganglioside GM3 induces CD4 internalization in human peripheral blood T lymphocytes.

Gangliosides modulate the expression of CD4 molecules on the cell surface of T lymphocytes. We report here that treatment of human peripheral blood lymphocytes with exogenous monosialoganglioside GM3 induces a rapid down-modulation of the CD4 molecules on the plasma membrane of CD4+ T lymphocytes, as assessed by cytofluorimetric analysis and quantitative immunoelectron microscopy. The CD4 down-modulation was ganglioside-dose dependent and was already evident after 5 min of treatment, reaching the maximum after 20 min. The expression of other surface antigens was not affected by GM3 treatment. The immunoelectron microscopic analysis showed that, following GM3 addition, gold labelled CD4 molecules were rapidly redistributed on the cell surface, clustered and internalized via endocytic pits and vesicles. These results indicate that CD4 down-modulation induced by GM3 occurs through an endocytic mechanism. A persistent low level of CD4 expression on the cell surface up to 24 h after GM3 treatment, compared with a stable expression of either CD4 in untreated cells and CD3 in GM3-treated cells, suggests intracellular degradation of the internalized CD4 molecules.

CD4 Antigens↗
PubMed1995

[Role of polychemoembolization in the treatment of primary and secondary tumors of the liver].

UNLABELLED: Unresectable primary hepatocellular carcinoma (HC) and liver metastases (LM) of abdominal tumors (AT) in progression after systemic chemotherapy (CT) have a poor prognosis and few therapeutic options. From 12/91 to 10/93 we treated 20 patients (PTS) 11 men and 9 women, with HC (10) and AT (10) with the following PCE: percutaneous placement of intraarterial hepatic catheter, superselective embolization with lipiodol (5 cc), infusion, mixed with lipiodol, of epirubicine 40 mg/m2, 5-fluorouracil 700 mg/m2, mitomycin-C 10 mg/m2 in 30'. After infusion, the arterial tree was embolized with Ivalon until an almost complete slowing of arterial blood-flow, every 5-6 weeks (W). After a median follow-up of 28 W a total of 35 courses had been administered to 20 PTS. Median (M) age was 69 years. M PS was 2. Okuda stage in HC PTS: 1 stage I, 9 stage II. in 10 HC PTS, positive for hepatitis B virus, CT and b-IFN had failed, while 10 AT PTS (5 colorectal, 2 gastric, 1 uterine, 1 larynx, 1 choledochus) had progressed, after, at least, 2 CT regimens, and had only LM. Median time from the diagnosis of LM in AT PTS was 32 W (12-68). TOXICITY: liver enzyme elevation and LDH elevation were 3 times baseline values, 4 PTS had fever for 6 days, 3 PTS had ileus for 3 days. No myelosuppression was observed. M alpha-fetoprotein value decreased from 468 ng/ml, to 56 ng/ml after PCE.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Beta-interferon, retinoids and tamoxifen as maintenance therapy in metastatic breast cancer. A pilot study.

BACKGROUND: Chemotherapy (CT), fundamental for the treatment of metastatic breast cancer (MBC), rarely cures, due to the presence of minimal residual disease (MRD). Based on the synergistic antiproliferative effect of interferon, retinoids and tamoxifen on breast cancer cell lines, we designed a pilot study to test if a combination of beta-interferon (beta-IFN), retinoids and tamoxifen could improve the progression free survival and overall survival in patients (PTS) treated with CT for MBC. METHODS: Thirty-six patients, with stage IV carcinoma of the breast, were treated with a combination of Cyclophosfamide, 5-fluorouracil, 4-epidoxorubicin, vincristine and prednisone every 3 weeks for six courses (FECPV), followed by two courses of methotrexate, mitomycin-c and mitoxantrone (MMM). Treatment was continued, in response, with low dose beta-interferon, retynil palmitate and tamoxifen until disease relapse. RESULTS: Among 36 evaluable PTS, 23 achieved a clinical response (64%) (95% c. i. 48 x 80%), 7 had disease stability (19%), and 6 (17%) progressed. Leukopenia occurred in 15 patients, thrombocytopenia in six, and anemia in 11. 16 patients had nausea/vomiting; stomatitis was observed in nine patients and diarrhea in three. Toxicity of maintenance therapy was mild and mainly hepatic. Median response duration was 31 months (range 5-75+). Median overall survival was 32 months (9-83+). CONCLUSIONS: Our study shows that this regimen is feasible and shows activity in MBC with an acceptable toxicity.

Adult↗
PubMed1994

Human immunodeficiency virus type-1 tat enhances interleukin-2 promoter activity through synergism with phorbol ester and calcium-mediated activation of the NF-AT cis-regulatory motif.

Interference with T cell activation signals by Human immunodeficiency virus (HIV) gene products is suggested to contribute to the impairment of immune functions observed in AIDS. Interleukin-2 (IL-2) and HIV share common stimulatory signals triggered during T cell activation. The role of HIV tat, which is the main enhancing factor for viral LTR, in the regulation of IL-2 gene transcription has been studied following transient expression of the tat gene in phorbol ester and calcium ionophore-activated Jurkat cells transfected with IL-2 promoter-chloramphenicol acetyltransferase reporter constructs. We observed that tat increased the IL-2 promoter transcriptional activity in response to phorbol ester and ionomycin. This tat-dependent synergism mapped to the (-279 to -263 bp) NFAT motif of the IL-2 enhancer, which was sufficient to be transactivated by tat. Our data suggest that tat links T cell activating signals to the shared IL-2 and HIV regulation. This may play a role in the early phase of HIV infection.

Calcium↗
PubMed1994

CD44 triggering enhances human NK cell cytotoxic functions.

CD44, a major hyaluronate receptor, is involved in a variety of lymphocyte functions including lympho-hemopoiesis, adhesion to high endothelial venules or the extracellular matrix, and T cell activation. Here we investigated the ability of CD44 to affect the cytotoxic functions of human NK cells. Ligation of CD44 by selected mAb (J173 and F10442) resulted in a rapid, dose-response-dependent enhancement of NK cytotoxic activity against a panel of tumor target cells that varied in their sensitivity to NK killing. Neither enhanced killing against NK-resistant target cells nor CD44 mAb-mediated redirected lysis was not observed. CD44 cross-linking also was found to up-regulate CD16-mediated lysis. In an attempt to investigate the early biochemical events that occur after CD44 ligation, we found that optimal cross-linking conditions induce a rapid increase of intracellular free calcium levels, which is abrogated by extracellular Ca2+ chelation. Moreover, enhanced and more sustained Ca2+ rise resulted from CD16 and CD44 coengagement. In contrast, no inositol 1,4,5-trisphosphate generation was found after optimal CD44 cross-linking. These results suggest that although CD44 is not capable of delivering a lytic signal in human NK cells, it coactivates spontaneous or CD16-mediated NK cytotoxicity. The variation in intracellular free calcium may be one of the signals that account for the costimulation of the lytic activity.

Antibodies, Monoclonal↗
PubMed1994

Positive and negative regulation of the composite octamer motif of the interleukin 2 enhancer by AP-1, Oct-2, and retinoic acid receptor.

The differentiating agent retinoic acid (RA) has been previously reported to interfere with 12-O-tetradecanoyl-phorbol-13-acetate (TPA)/Ca2+-induced signals for the regulation of the -96 to -66-bp octamer motif found in the enhancer for the interleukin (IL)-2 gene, which encodes a major T lymphocyte growth factor. The IL-2 octamer motif is a composite cis-element which binds Oct-1 and Oct-2 as well as a TPA/Ca2+-inducible nuclear factor, previously termed octamer-associated protein (OAP40). We show here that Oct-2, despite the presence of an active transcriptional activation domain, requires TPA/Ca2+-induced signals to strongly transactivate the IL-2 octamer motif in Jurkat T cells. This Oct-2-dependent transactivation is inhibited by RA. The presence of an intact COOH-terminal domain of Oct-2 contributes to both TPA/Ca2+-induced transactivation and the RA-mediated repression. We also show that both Fos and Jun components of the AP-1 factors participate in the OAP40 complex. Furthermore, transfected c-jun, jun-B, jun-D, c-fos, or Fos-B expression vectors partially substitute for TPA and Ca2+ and cooperate with Oct-2 for the transactivation of the combined OAP/octamer cis-element. Mutations of the genuine octamer-binding site abrogate both the binding of Oct-1 and Oct-2 and the TPA/Ca2+-induced transactivation of the OAP/octamer motif. OAP confers to Oct-2 responsivity to both TPA/Ca2+ and RA, since specific mutations of the AP-1/OAP-binding site significantly reduce the transactivation by Oct-2 in response to TPA and Ca2+ and abolish the inhibition by RA. Furthermore, retinoic acid receptor (RAR) alpha is able to inhibit in vitro the formation of the complex between the nuclear AP-1/OAP and its specific binding site, resulting in the interference with Oct-2-dependent cis-regulatory function of this AP-1 element. Therefore, we propose that the TPA/calcium-activated AP-1/OAP element is the main target of positive or negative regulatory signals influencing the IL-2 octamer motif, through synergism with Oct-2 and antagonism by RAR.

Base Sequence↗
PubMed1994

Modulation of fibronectin and thymic stromal cell-dependent thymocyte maturation by retinoic acid.

Retinoic acid (RA) controls the differentiation of a variety of cell types, although its role in influencing T cell development and the mechanisms potentially involved have not been thoroughly investigated. To study the ability of RA to modulate T cell development, we established a thymic stromal cell line (TC-1S) that supports the phenotypic maturation of CD4-8- double negative (DN) or CD3-4-8- triple negative (TN) thymocyte precursors. Cocultures of either DN or TN thymocytes on a monolayer of TC-1S cells resulted in the appearance of thymocytes with a more mature phenotype (CD4+8+ double positive, CD4+ or CD8+ single positive, and CD3(low) cells). Double negative T cell contact with TC-1S cells also increased the production of fibronectin (FN) by the thymic stroma and the expression of the VLA-4 FN receptor on the DN cells. Ab-mediated inhibition of the interaction between FN and its receptors significantly reduced the level of induced T cell maturation. Addition of RA either to TC-1S cells alone or to the coculture with DN cells decreased stromal cell FN expression, antagonized DN cell-induced increase in stromal cell FN production and significantly inhibited in vitro thymocyte maturation. The effects of RA were likely mediated by RA acid receptors alpha and gamma expressed both in DN thymocytes and TC-1S cells. Together these data suggest that FN/VLA-4 interaction may be an important component of stromal cell-dependent thymocyte phenotypic differentiation and that this interaction can be one of the targets for the influence of RA in T cell development.

Animals↗
PubMed1994

Long term activation of natural killer cells results in modulation of beta 1-integrin expression and function.

Integrin expression and function is largely modulated by cell activation. Here we provide evidence that long term activation of human NK cells results in a marked modulation of beta 1-integrin expression and adhesive functions. By flow cytometry and immunochemical analysis we have detected induction of alpha 1 beta 1 and alpha 2 beta 1, increased expression of alpha 4 beta 1 and alpha 5 beta 1, and decline of alpha 6 beta 1 on CD3-CD56+ NK cells generated from 10-day coculture of nonadherent PBMC with irradiated RPMI 8866 EBV+ lymphoblastoid B cell line. Adhesion assays performed on extracellular matrix-coated plates showed that, unlike fresh NK cells, long term-activated NK cells bind to native collagen I via alpha 2 beta 1 and to heat-denatured collagen I in an RGD-dependent manner, although they lose the ability to bind to laminin. In regard to the adhesion to FN, no major quantitative changes are observed after long term NK cell activation. However, whereas alpha 4 beta 1 and alpha 5 beta 1 completely mediate the adhesion of fresh NK cells to fibronectin, binding of activated NK cells is only partially beta 1-dependent and seems to involve also non-beta 1-integrin(s) recognizing and RGD sequence. The modulation of beta 1-integrin expression and the acquisition of new adhesive properties on long term-activated NK cells may be relevant for their traffic and tissue localization during inflammation and immune response.

Amino Acid Sequence↗
PubMed1994

Involvement of p21ras activation in T cell CD69 expression.

The involvement of p21ras in the induction of the early activation antigen CD69 was investigated in T cells. Expression of a v-Ha-ras coding for a constitutively active ras protein in Jurkat cells resulted in CD69 induction on the cell surface. Transfected ras was shown to be constitutively activated and functionally efficient, since it could be immunoprecipitated in the guanosine triphosphate (GTP)-bound form and it induced transactivation of an AP-1 consensus-chloramphenicol acetyltransferase reporter gene. The requirement for ras activation in T cell receptor (TcR) CD3-mediated CD69 induction was also investigated. The expression of a dominant negative c-Ha-ras-N17 mutant markedly reduced the amount of GTP that could be immunoprecipitated from ras proteins after TcR/CD3 triggering in Jurkat cells, and concomitantly decreased TcR/CD3-mediated CD69 induction. These results suggest a central role for ras in TcR/CD3-mediated CD69 expression in T cells.

Antigens, CD↗
PubMed1994

HHV-6 infection in Italy: characterization of an endemic isolate and seroepidemiologic analysis.

A biologic, immunologic and molecular characterization of an HHV-6 isolate (BA92) rescued by the peripheral blood mononuclear cells of a child affected by Exanthem subitum is reported. The comparison with the known HHV-6 prototype strains showed that BA92 is indistinguishable from the Z29 isolate, and can be included in the variant B group of HHV-6. A seroepidemiologic analysis of the antibody response to BA92 of normal individuals as well as patients affected by diseases potentially associated to HHV-6 infection has shown an overall seroprevalence of 81%, and that no variations in seroprevalence or in antibody geometric mean titer are observed assaying the sera also against G.S., U1102, or Z29 infected cells, respectively. These findings indicate: (1) HHV-6 infection is widely diffuse in Italy; (2) it is not possible to discriminate between the viral variants by the currently available IF assays, and (3) no conclusions can be drawn on the potential association of HHV-6 with any of the diseases examined.

Journal Article↗
PubMed1994

Estrogen receptors: new perspectives in breast cancer management.

The imbalance between proliferative and differentiative estrogenic effect, caused by quantitative and qualitative alteration of the estrogen receptor (ER) expression, may play a determinant role in mammary neoplastic transformation. Our studies demonstrate that ER levels are significantly higher in human mammary neoplastic tissues when compared to perineoplastic tissues and that increased ER expression is associated with ER gene hypomethylation. During progressive multifactorial carcinogenesis, ER overexpression may represent an early step in neoplastic transformation. In fact, high levels of ER represent good markers of differentiation and can predict the likelihood of benefiting from anti-estrogen therapy. Nevertheless, about 35% of ER-positive breast cancers are resistant to endocrine therapy and 10% of ER-negative tumors behave as hormone-sensitive tumors. Recent studies on ER mRNA variants, which naturally occur in human breast tumors, demonstrated mutations, deletions and alternative splicings, yielding deletions of exons 3, 4, 5 and 7. ER variants exhibited altered functions or changed the responsiveness to hormonal therapy. Analysis of these variants could be a useful parameter to better predict tumor responsiveness to anti-estrogen therapy. Recently, a regain of hormonal responsiveness by ER-negative breast cancer cells has been reported following ER gene transfection. However, estradiol treatment inhibits rather than stimulates cell growth as well as the metastatic and invasive potential of the ER gene transduced cells. Transfer of the ER gene may be considered as a new therapeutic approach in the management of hormone-independent breast cancer.

Breast Neoplasms↗
PubMed1994

Candida albicans expresses a fibronectin receptor antigenically related to alpha 5 beta 1 integrin.

Cell adhesion molecules, by regulating host-micro-organism interaction, play a major role in the pathogenesis of infectious diseases. The present study was undertaken to investigate the expression of the fibronectin (FN) receptor prototype, alpha 5 beta 1 integrin, on Candida albicans and its involvement in the adhesion to FN. By immunofluorescence and fluorescence activated cell sorter (FACS) analysis, several monoclonal antibodies (mAbs) directed against human alpha 5 or beta 1 integrin subunits, or two different antisera to FN receptor positively stained C. albicans yeast and germ tube phases, this immunoreactivity increasing upon germ tube transition. Twenty-five to thirty per cent of [3H]glucose-labelled Candida yeasts specifically adhered to FN and this adhesion was increased upon germ tube transition. C. albicans yeast and germ tube forms bound to an RGD-containing 120 kDa tryptic fragment of FN and adhesion to FN was markedly inhibited by GRGDSP, but not GRGESP peptides. Moreover, binding of both C. albicans phases to FN was strongly inhibited by anti-alpha 5 SAM-1 mAb, or both anti-fibronectin receptor (FNr) antisera. Overall these results indicate that C. albicans yeast and germ tube phases express a receptor antigenically related to alpha 5 beta 1 integrin which mediates their adhesion to FN. The alpha 5 beta 1 integrin-like receptor expression on C. albicans could be relevant for fungus-host interaction and in the dissemination process of Candida infection.

Antigens, Fungal↗
PubMed1994

Events related to Epstein-Barr virus binding and superinfection of Raji cells.

Raji cells, a CR2-positive Burkitt lymphoma cell line, incubated in normal human serum, activate C3 and fix C3-derived fragments. The presence of these molecules on the cell surface does not affect subsequent Epstein-Barr virus (EBV) binding but it prevents superinfection. On the other hand, EBV superinfection is enhanced if Raji cells were incubated with heat-inactivated serum whose C3 fragments may bind only through receptor-binding sites. These results indicate that the region on cell surface offering the covalent site to C3 fragments would be essential for EBV superinfection. Incubation of Raji cells for 1 min with EBV results in the phosphorylation of CR2 and of a high-molecular-weight protein followed by their dephosphorylation, completed already after 20 min. This finding ascribes to EBV a prompt action through its receptor, different from that of other compounds causing a prolonged CR2 phosphorylation. Our data suggest that at least two binding sites are required for EBV superinfection of Raji cells or that specific patterns of CR2 phosphorylation may modulate Raji superinfection by EBV.

Binding Sites↗
PubMed1994

Detection of human papillomavirus type 16 DNA sequences in paraffin-embedded tissues from the female urinary tract.

We investigated the presence of human papillomavirus-related DNA sequences (HPV 6, 11, 16 and 18) in 33 formalin-fixed paraffin-embedded biopsies from the urinary tract of female patients with recurrent and persistent urethritis and cystitis, using the polymerase chain reaction (PCR). The samples for PCR reaction were selected among tissues examined for histological diagnosis on the basis of the presence of microscopic changes consistent with HPV infection. Sequences homologous to HPV 6, 11 and 18 genome were not found, while HPV 16-related DNA sequences were identified in 25/33 lesions with histopathological diagnosis of metaplasia (1 from the urethra, 23 from the trigone and 1 from the bladder). The results suggest that the spread of HPV in the female urinary tract may not be uncommon and point to the need for further research on the possible pathogenic role in recurrent female disturbances.

Cystitis↗
PubMed1994

High frequency of human papillomavirus detection in urinary bladder cancer.

We investigated the presence of human papillomaviruses (HPVs) types 16 and 18 DNA in formalin-fixed, paraffin-embedded tissues from the urinary bladder (46 transitional carcinomas and 10 non-neoplastic normal urinary samples) to find a possible role for HPV types in urinary tract cancerogenesis. The analysis was performed using polymerase chain reaction followed by filter hybridization with oligonucleotide-specific probes. The HPV16 and/or HPV18 genomes were detected in 23 of 46 (50%) bladder carcinomas and in none of 10 (0%) non-neoplastic urinary samples. These results suggest that HPV16 and 18 may carry a risk for the development of malignancy in the urinary tract as it occurs in the anogenital regions.

Carcinoma, Transitional Cell↗
PubMed1994

Paleopathology of the Copper Age mummy from the Val senales glacier.

The unique conditions of preservation of the Copper age mummy found in the Val Senales glacier permit to analyze the general state of health of a man of the late European prehistory. Investigations conducted within the organizational framework of an International Research Project revealed the presence of a series of alterations, that, in a broad sense, can be considered of paleopathological interest. These can be classified as: 1) post mortem lesions, including scalp erosion, alopecia, soft tissue loss in the right gluteal region, right coxo-femoral disarticulation, right sacro-iliac dislocation; 2) lesions that occurred intra vitam, including tattooings, dental wear, trichorrexis nodosa, nail hypoplasia, moderate osteoarthrosis of the lumbar vertebral column and of the coxo-femoral joints, tibio-tarsal osteosclerosis. The palaeopathological analysis of this unique mummy shed vivid light on the mutual interactions between disease, environment, and culture, that shaped human life in a distant past.

Austria↗