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F Baldassarre

Publications and source records attributed to F Baldassarre.

12 recordsLinked to original sources
PubMed2000

Prion diseases: a typical Kuhnian abnormality in a molecular paradigm.

As a new class of pathogens with unusual properties, prions have been implied in several spongiform encephalopathies mainly affecting farm animals (scrapie, mad-cow disease) and humans (kuru, Creutzfeldt-Jacob disease, fatal familial insomnia) (1). The term prions underlines the feature that the agents would merely consist of a protein (2), perhaps a pathological counterpart of a cellular constituent with poorly defined functions (3-5). In reviewing relevant literature, in order to test the validity of the 'protein-only hypothesis' for coherence and consistency with a molecular paradigm, we have met evident discrepancies, making prion diseases a typical abnormality in a Kuhnian sense. This paper summarizes and analyses the main features of the protein-only model.

Animals↗
PubMed1999

Potent and stable attenuation of live-HIV-1 by gain of a proteolysis-resistant inhibitor of NF-kappaB (IkappaB-alphaS32/36A) and the implications for vaccine development.

Live-attenuated human immunodeficiency viruses (HIVs) are candidates for Acquired Immunodeficiency Syndrome (AIDS) vaccine. Based on the simian immunodeficiency virus (SIV) model for AIDS, loss-of-function (e.g. deletion of accessory genes such as nef) has been forwarded as a primary approach for creating enfeebled, but replication-competent, HIV-1/SIV. Regrettably, recent evidence suggests that loss-of-function alone is not always sufficient to prevent the emergence of virulent mutants. New strategies that attenuate via mechanisms distinct from loss-of-function are needed for enhancing the safety phenotype of viral genome. Here, we propose gain-of-function to be used simultaneously with loss-of-function as a novel approach for attenuating HIV-1. We have constructed an HIV-1 genome carrying the cDNA of a proteolysis-resistant nuclear factor-kappaB inhibitor (IkappaB-alphaS32/36A) in the nef region. HIV-1 expressing IkappaB-alphaS32/36A down-regulates viral expression and is highly attenuated in both Jurkat and peripheral blood mononuclear cells. We provide formal proof that the phenotypic and attenuating characteristics of IkappaB-alphaS32/36A permit its stable maintenance in a live, replicating HIV-1 despite 180 days of forced ex vivo passaging in tissue culture. As compared with other open-reading frames embedded into HIV/SIV genome, this degree of stability is unprecedented. Thus, IkappaB-alphaS32/36A offers proof-of-principle that artifactually gained functions, when used to attenuate the replication of live HIV-1, can be stable. These findings illustrate gain-of-function as a feasible strategy for developing safer live-attenuated HIVs to be tested as candidates for AIDS vaccine.

AIDS Vaccines↗
PubMed1998

Computerization in breast imaging and diagnosis.

Computerization in breast imaging is very important for activity management and for the qualitative and quantitative control of the diagnoses. The connection through a personal computer network is necessary for the simultaneous input of more data. The activity in our center is completely managed by a specific software which controls and facilitates the input of all personal, administrative, history, instrumental and pathological data. The encoded case history permits quick and accurate data input and the relative information is easy to understand. Database information can be used to make periodical administrative and diagnostic reports and queries, to elaborate useful data for scientific reports and to manage didactic material. The growing use of computers will permit the exchange of data among breast imaging centers and also create important data banks for breast cancer studies.

Ambulatory Care Information Systems↗
PubMed1996

An NF-kappaB site in the 5'-untranslated leader region of the human immunodeficiency virus type 1 enhances the viral expression in response to NF-kappaB-activating stimuli.

The 5'-untranslated leader region of human immunodeficiency virus, type 1 (HIV-1), includes a complex array of putative regulatory elements whose role in the viral expression is not completely understood. Here we demonstrate the presence of an NF-kappaB-responsive element in the trans-activation response (TAR) region of HIV-1 that confers the full induction of HIV-1 long terminal repeat (LTR) in response to NF-kappaB-activating stimuli, such as DNA alkylating agents, phorbol 12-myristate 13-acetate, and tumor necrosis factor-alpha. The TAR NF-kappaB site GGGAGCTCTC spans from positions +31 to +40 and cooperates with the NF-kappaB enhancer upstream of the TATA box in the NF-kappaB-mediated induction of HIV-1 LTR. The conclusion stems from the following observations: (i) deletion of the two NF-kappaB sites upstream of the TATA box reduces, but does not abolish, the HIV-1 LTR activation by NF-kappaB inducers; (ii) deletion or base pair substitutions of the TAR NF-kappaB site significantly reduce the HIV-1 LTR activation by NF-kappaB inducers; (iii) deletions of both the NF-kappaB sites upstream of the TATA box and the TAR NF-kappaB site abolish the activation of HIV-1 LTR in response to NF-kappaB inducers. Moreover, the p50 p65 NF-kappaB complex binds to the TAR NF-kappaB sequence and trans-activates the TAR NF-kappaB-directed expression. The identification of an additional NF-kappaB site in the HIV-1 LTR points to the relevance of NF-kappaB factors in the HIV-1 life cycle.

Base Sequence↗
PubMed1995

Regulation of NF-kappa B through the nuclear processing of p105 (NF-kappa B1) in Epstein-Barr virus-immortalized B cell lines.

Transcription factors of the NF-kappa B/Rel family are retained in the cytoplasm as inactive complexes through association with I kappa B inhibitory proteins. Several NF-kappa B activators induce the proteolysis of I kappa B proteins, which results in the nuclear translocation and DNA binding of NF-kappa B complexes. Here, we report a novel mechanism of NF-kappa B regulation mediated by p105 (NF-kappa B1) precursor of p50 directly at the nuclear level. In Epstein-Barr virus-immortalized B cells, p105 was found in the nucleus, where it was complexed with p65. In concomitance with NF-kappa B activation, mitomycin C induced the processing of p105 to p50 in the nucleus, while it did not affect the steady-state protein levels of I kappa B alpha and p105 in the cytoplasm. Differently, phorbol 12-myristate 13-acetate induced a significant proteolysis of both I kappa B alpha and p105 in the cytoplasm, while it did not affect the protein level of p105 in the nucleus. These results suggest that in Epstein-Barr virus-positive B cell lines the nuclear processing of p105 can contribute to NF-kappa B activation in response to specific signaling molecules, such as DNA-damaging agents.

B-Lymphocytes↗
PubMed1994

The expression of the interleukin 6 gene is induced by the human immunodeficiency virus 1 TAT protein.

Human immunodeficiency virus 1 (HIV1) infection is associated with severe psoriasis, B cell lymphoma, and Kaposi's sarcoma. A deregulated production of interleukin 6 (IL-6) has been implicated in the pathogenesis of these diseases. The molecular mechanisms underlying the abnormal IL-6 secretion of HIV1-infected cells may include transactivation of the IL-6 gene by HIV1. To test this hypothesis, we used the pIL6Pr-chloramphenicol acetyltransferase (CAT) plasmid, an IL-6 promoter-CAT construct, as a target of the transactivating function of the HIV1 TAT protein. By cotransfecting the pIL6Pr-CAT and the tat-expressing pSVT8 plasmid in MC3 B-lymphoblastoid or in HeLa epithelial cells, we observed that TAT transactivates the human IL-6 promoter. These results were confirmed when pIL6Pr-CAT was transfected in MC3 or HeLa cells that constitutively expressed the tat gene in a sense (pSVT8 cells) or antisense (pSVT10 cells) orientation. 5' deletion plasmids of pIL6Pr-CAT, in which regions at -658, -287, and -172 were inserted 5' to the cat gene, were transiently transfected in pSVT10 and pSVT8 cells and showed that TAT-induced activation of the IL-6 promoter required a minimal region located between -287 and -54 bp. Moreover, experiments with plasmids carrying the -658, -287, and -172 bp regions of the IL-6 promoter inserted downstream to a TAR-deleted HIV1-LTR identified the sequence of -172 to -54 as the minimal region of the IL-6 promoter required for TAT to transactivate the TAR-deleted HIV1-LTR. By DNA-protein binding experiments, tat-transfected cells expressed a consistent increase in kappa B and nuclear factor (NF)-IL-6 binding activity. Accordingly, the pDRCAT and IL-1REK9CAT, carrying tandem repeats of NF-kappa B or NF-IL6 binding motifs, respectively, were activated in TAT-expressing cells. The biological relevance of the TAT-induced IL-6 secretion was addressed by generating 7TD1 cells, an IL-6-dependent mouse cell line, stably expressing the tat gene. These tat-positive cells expressed the endogenous IL-6 gene, secreted high amounts of murine IL-6, and grew efficiently in the absence of exogenous IL-6. Moreover, the tat-positive 7TD1 cells sustained the growth of parental 7TD1 cells and showed a dramatic increase in their tumorigenic potency. These results suggest that TAT protein may play a role in the pathogenesis of some HIV1-associated diseases by modulating the expression of host cellular genes.

Animals↗
PubMed1993

The human immunodeficiency virus type 1 long terminal repeat is activated by monofunctional and bifunctional DNA alkylating agents in human lymphocytes.

The activation of the human immunodeficiency virus, type 1 (HIV-1) by the DNA alkylating agents ethyl methanesulfonate, methyl methanesulfonate, and mitomycin C was observed in human B lymphocytes transiently transfected with plasmids in which the HIV-1 long terminal repeat (LTR) directed the expression of the bacterial chloramphenicol acetyltransferase gene. Deletion of the two NF-kappa B-binding sites of LTR abolished the HIV-1 activation induced by the three mutagens, while deletion of the three Sp1-binding sites slightly reduced it. Electrophoretic mobility shift assays revealed an increased binding to the kappa B sites of HIV-1 LTR in the nuclear extracts of human B lymphocytes upon mutagen treatment, while binding to Sp1 sites was unaffected. The TAR region was also involved in the mutagen-mediated activation of HIV-1 LTR inasmuch as a small deletion in the TAR sequence (nucleotides +34 to +37) greatly decreased the induction of HIV-1 expression. Moreover, an enhanced binding activity to the TAR DNA sequence (nucleotides +24 to +47) was observed in nuclear extracts of mutagen-treated lymphocytes. Thus, both the enhancer and the 5'-untranslated region of HIV-1 functionally cooperate in the mutagen-mediated induction of HIV-1 expression.

Alkylating Agents↗
PubMed1992

Serum and tissue transglutaminase correlates with the severity of inflammation in induced colitis in the rat.

Simple rat models of acute and chronic colonic inflammation were used to study the behaviour in serum and mucosa of transglutaminase (TG), an enzyme recently found to be reduced in serum of patients with inflammatory bowel disease (IBD) and related to the activity index of the disease. In the first model the intraluminal administration of 400 mM lactic acid in the colon caused an acute inflammation resembling that of florid ulcerative colitis in humans. In the second, intraluminal administration of the hapten 2,4,6-trinitrobenzenesulphonic acid (TNB) (10 or 30 mg) in 0.25 ml of ethanol as a 'barrier breaker' produced a chronic inflammatory disease. The results showed a reduced TG activity in colon of rats in both acute and chronic induced colitis (447 +/- 75 versus 1344 +/- 59 mU/g protein (p less than 0.001) and 484 +/- 59 versus 1204 +/- 75 mU/g protein (p less than 0.001)). This decreased activity was related to the severity of mucosal damage, which was dose-dependent. Moreover, in severe colitis the immunohistochemistry showed a TG location in repairing tissue. Serum TG activity was decreased after TNB administration (1.36 +/- 0.05 versus 3.44 +/- 0.20 mU/ml (p less than 0.001)) but not after lactic acid treatment (3.97 +/- 0.11 versus 3.78 +/- 0.16 mU/ml). In summary, the reduction of TG activity in both tissue and serum when the damage is stabilized reflects the altered morphofunctional integrity of the colon and suggests that serum assay of this enzyme could be a simple marker of intestinal mucosal status in IBD.

Acute Disease↗