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Biomedical subjects

G Franchini

Publications and source records attributed to G Franchini.

At least 55 records · Page 3Linked to original sources
PubMed1998

Human herpesvirus 7 infection induces profound cell cycle perturbations coupled to disregulation of cdc2 and cyclin B and polyploidization of CD4(+) T cells.

Human herpesvirus 7 (HHV-7) infection of both primary CD4(+) T lymphocytes and SupT1 lymphoblastoid T-cell line induced a progressive accumulation of cells exibiting a gap 2/mitosis (G2/M) and polyploid content coupled to an increased cell size. The expression of both cyclin-dependent kinase cdc2 and cyclin B was increased in HHV-7-infected cells with respect to the uninfected ones. Moreover, the simultaneous flow cytometric analysis of cyclin B and DNA content showed that cyclin B expression was not only increased but also unscheduled with respect to its usual cell cycle pattern. However, the levels of kinase activity associated to cdc2 were decreased in HHV-7-infected cells with respect to uninfected cultures. To elucidate the origin of the enlarged HHV-7-infected cells, extensive electron and confocal microscopy analyses were performed. Membrane fusion events associated to cytoplasmic bridges, which characterize the formation of syncytia, were never observed. On the other hand, analysis of serial sections of the same cells strongly suggested that enlarged HHV-7-infected cells contained a single polylobated nucleus. This was confirmed by flow cytometry analysis performed on nuclei isolated from HHV-7-infected cells, which showed multiple peaks with a DNA content >4n. Taken together, these data indicate that giant cells, which represent the hallmark of in vitro HHV-7 infection, arise from single CD4(+) T cells undergoing a process of polyploidization.

CD4-Positive T-Lymphocytes↗
PubMed1998

Human T-cell lymphotropic/leukemia virus type 1 Tax abrogates p53-induced cell cycle arrest and apoptosis through its CREB/ATF functional domain.

Human T-cell lymphotropic/leukemia virus type 1 (HTLV-1) transforms human T cells in vitro, and Tax, a potent transactivator of viral and cellular genes, plays a key role in cell immortalization. Tax activity is mediated by interaction with cellular transcription factors including members of the CREB/ATF family, the NF-kappaB/c-Rel family, serum response factor, and the coactivators CREB binding protein-p300. Although p53 is usually not mutated in HTLV-1-infected T cells, its half-life is increased and its function is impaired. Here we report that transient coexpression of p53 and Tax results in the suppression of p53 transcriptional activity. Expression of Tax abrogates p53-induced G1 arrest in the Calu-6 cell line and prevents the apoptosis induced by overexpressing p53 in the HeLa/Tat cell line. The Tax mutants M22 and G148V, which selectively activate the CREB/ATF pathway, exert these same biological effects on p53 function. In contrast, the NF-kappaB-active Tax mutant M47 has no effect on p53 activity in any of these systems. Consistent with the negative effect of Tax on p53, no activity on a p53-responsive promoter was observed upon transfection of HTLV-1-infected T-cell lines. The p53 protein is expressed at high levels in the nucleus, and nuclear extracts of HTLV-1-infected T cells bind constitutively to a DNA oligonucleotide containing the p53 response element, indicating that Tax does not interfere with p53 binding to DNA. Tax is able to suppress the transactivation function of p53 in three different cell lines, and this suppression required Tax-mediated activation of the CREB/ATF, but not the NF-kappaB/c-Rel, pathway. Tax and the active Tax mutants were able to abrogate the G1 arrest and apoptosis induced by p53, and this effect does not correlate with an altered localization of nuclear p53 or with the disruption of p53-DNA complexes. The suppression of p53 activity by Tax could be important in T-cell immortalization induced by HTLV-1.

Activating Transcription Factor 2↗
PubMed1998

Recombinant vaccine-induced protection against the highly pathogenic simian immunodeficiency virus SIV(mac251): dependence on route of challenge exposure.

Vaccine protection from infection and/or disease induced by highly pathogenic simian immunodeficiency virus (SIV) strain SIV(mac251) in the rhesus macaque model is a challenging task. Thus far, the only approach that has been reported to protect a fraction of macaques from infection following intravenous challenge with SIV(mac251) was the use of a live attenuated SIV vaccine. In the present study, the gag, pol, and env genes of SIV(K6W) were expressed in the NYVAC vector, a genetically engineered derivative of the vaccinia virus Copenhagen strain that displays a highly attenuated phenotype in humans. In addition, the genes for the alpha and beta chains of interleukin-12 (IL-12), as well as the IL-2 gene, were expressed in separate NYVAC vectors and inoculated intramuscularly, in conjunction with or separate from the NYVAC-SIV vaccine, in 40 macaques. The overall cytotoxic T-lymphocyte (CTL) response was greater, at the expense of proliferative and humoral responses, in animals immunized with NYVAC-SIV and NYVAC-IL-12 than in animals immunized with the NYVAC-SIV vaccine alone. At the end of the immunization regimen, half of the animals were challenged with SIV(mac251) by the intravenous route and the other half were exposed to SIV(mac251) intrarectally. Significantly, five of the eleven vaccinees exposed mucosally to SIV(mac251) showed a transient peak of viremia 1 week after viral challenge and subsequently appeared to clear viral infection. In contrast, all 12 animals inoculated intravenously became infected, but 5 to 6 months after viral challenge, 4 animals were able to control viral expression and appeared to progress to disease more slowly than control animals. Protection did not appear to be associated with any of the measured immunological parameters. Further modulation of immune responses by coadministration of NYVAC-cytokine recombinants did not appear to influence the outcome of viral challenge. The fact that the NYVAC-SIV recombinant vaccine appears to be effective per se in the animal model that best mirrors human AIDS supports the idea that the development of a highly attenuated poxvirus-based vaccine candidate can be a valuable approach to significantly decrease the spread of human immunodeficiency virus (HIV) infection by the mucosal route.

Animals↗
PubMed1998

Human and simian T-cell leukemia viruses type 2 (HTLV-2 and STLV-2(pan-p)) transform T cells independently of Jak/STAT activation.

Human T-lymphotropic virus type 1 (HTLV-1) and HTLV-2 differ in pathogenicity in vivo. HTLV-1 causes leukemia and neurologic and inflammatory diseases, whereas HTLV-2 is less clearly associated with human disease. Both retroviruses transform human T cells in vitro, and transformation by HTLV-1 was found to be associated with the constitutive activation of the Jak/STAT pathway. To assess whether HTLV-2 transformation may also result in constitutive activation of the Jak/STAT pathway, six interleukin-2-independent, HTLV-2-transformed T-cell lines were analyzed for the presence of activated Jak and STAT proteins by electrophoretic mobility shift assay. In addition, the phosphorylation status of Jak and STAT proteins was assessed directly by immunoprecipitation and immunoblotting with an antiphosphotyrosine antibody. Jak/STAT proteins were not found to be constitutively activated in any of the T-cell lines infected by the type 2 human and nonhuman primate viruses, suggesting that HTLV-2 and the cognate virus simian T-lymphotropic virus type 2 from Pan paniscus transform T cells in vitro by mechanisms at least partially different from those used by HTLV-1.

Animals↗
PubMed1997

Proliferation of adult T cell leukemia/lymphoma cells is associated with the constitutive activation of JAK/STAT proteins.

Human T cell leukemia/lymphotropic virus type I (HTLV-I) induces adult T cell leukemia/lymphoma (ATLL). The mechanism of HTLV-I oncogenesis in T cells remains partly elusive. In vitro, HTLV-I induces ligand-independent transformation of human CD4+ T cells, an event that correlates with acquisition of constitutive phosphorylation of Janus kinases (JAK) and signal transducers and activators of transcription (STAT) proteins. However, it is unclear whether the in vitro model of HTLV-I transformation has relevance to viral leukemogenesis in vivo. Here we tested the status of JAK/STAT phosphorylation and DNA-binding activity of STAT proteins in cell extracts of uncultured leukemic cells from 12 patients with ATLL by either DNA-binding assays, using DNA oligonucleotides specific for STAT-1 and STAT-3, STAT-5 and STAT-6 or, more directly, by immunoprecipitation and immunoblotting with anti-phosphotyrosine antibody for JAK and STAT proteins. Leukemic cells from 8 of 12 patients studied displayed constitutive DNA-binding activity of one or more STAT proteins, and the constitutive activation of the JAK/STAT pathway was found to persist over time in the 2 patients followed longitudinally. Furthermore, an association between JAK3 and STAT-1, STAT-3, and STAT-5 activation and cell-cycle progression was demonstrated by both propidium iodide staining and bromodeoxyuridine incorporation in cells of four patients tested. These results imply that JAK/STAT activation is associated with replication of leukemic cells and that therapeutic approaches aimed at JAK/STAT inhibition may be considered to halt neoplastic growth.

Adult↗
PubMed1997

Didanosine but not high doses of hydroxyurea rescue pigtail macaque from a lethal dose of SIV(smmpbj14).

It has been previously reported that hydroxyurea (HU) displays anti-HIV-1 activity and potentiates the antiviral effects of didanosine (ddI) in vitro. To assess the antiviral efficacy of HU in an animal model, the effects of HU and ddI, either individually or as combination therapy, were tested in a model using infection of pigtail macaque with the acutely fatal variant SIV(smpbj14). At the high dosage used (100 mg/kg/day), HU monotherapy failed to protect the exposed animals from viral infection and death, which occurred within 10 days postinoculation. However, both of the ddI-treated animals (5 mg/kg/day) survived the SIV(smmpbj14) lethal dose and displayed a reduction in viral load (undetectable SIV RNA or p27gag) in the primary phase of infection. Of the animals treated with the combination of drugs, one died at day 18 after infection and failed to seroconvert to viral antigens. These data suggest that a high dose of HU monotherapy does not protect against death induced by SIV(mmpbj14). However, lower doses of HU as monotherapy or combination therapy deserve further evaluation for their therapeutic effects.

Animals↗
PubMed1997

The tax gene sequences form two divergent monophyletic lineages corresponding to types I and II of simian and human T-cell leukemia/lymphotropic viruses.

Evolutionary associations of human and simian T-cell leukemia/lymphotropic viruses I and II (HTLV-I/II and STLV-I/II) are inferred from phylogenetic analysis of tax gene sequences. Samples studied consisted of a geographically diverse assemblage of viral strains obtained from 10 human subjects and 20 individuals representing 12 species of nonhuman primates. Sequence analyses identified distinct substitutions, which distinguished between viral types I and II, irrespective of host species. Phylogenetic reconstruction of nucleotide sequences strongly supported two major evolutionary groups corresponding to viral types I and II. With the type I lineage, clusters were composed of strains from multiple host species. A genetically diverse, monophyletic lineage consisting of eight new viral strains from several species of Asian macaques was identified. The second lineage consisted of a monophyletic assemblage of HTLV-II/STLV-II strains from Africa and the New World, including an isolate from a pygmy chimp (Pan paniscus) as an early divergence within the lineage. High levels of genetic variation among strains from Asian STLV-I macaque suggest the virus arose in Asia. Evidence of the origin of the type II virus is less clear, but diversity among HTLV-II variants from a single isolated population of Mbati villagers is suggestive but not proof of an African origin.

Amino Acid Sequence↗
PubMed1997

Human herpes virus 6 and human herpes virus 8 DNA sequences in brains of multiple sclerosis patients, normal adults and children.

In order to determine whether the newly discovered human herpesviruses (HHVs) are involved in multiple sclerosis (MS), we investigated by polymerase chain reaction the presence of specific deoxyribonucleic acid (DNA) sequences belonging to human herpesvirus 6 (HHV-6) and to human herpesvirus 8 (HHV-8), in the peripheral blood mononuclear cells (PBMCs), and in the brain and spinal cord plaques from MS patients. Normal adult and stillborn children's brains were investigated as controls. PBMCs from 56 MS patients contained HHV-6 DNA in only 3 cases and in none were there HHV-8 sequences. The cerebral DNA from 5 MS patients was positive for HHV-8 and not for HHV-6 sequences, while the nervous tissue of one patient who died with neuromyelitis optica was positive for HHV-6 and negative for HHV-8. The brains of 4/8 adult controls were positive for HHV-6, as were 3/8 for HHV-8; none of the 7 stillborn children's cerebral tissue contained HHV-6 sequences, while 2 contained HHV-8 DNA. Although these data do not support a hypothesis that there is a role for these two HHVs in the pathogenesis of MS, nevertheless it may be suggested that (1) the two viruses possess strong neurotropism and the central nervous system seems to be a reservoir for them (2) HHV-6 infection is probably not transmitted maternally, but is acquired later in infancy.

Adult↗
PubMed1997

Differential expression of alternatively spliced pX mRNAs in HTLV-I-infected cell lines.

Human T cell leukemia/lymphotropic virus (HTLV) is a complex 9 kb human retrovirus with at least eight alternatively spliced mRNAs expressed from the 3' or pX region of the genome. These mRNAs allow for the expression of novel proteins from the previously recognized pX open reading frames I and II in addition to Tax, Rex and p21rex encoded from orf III and IV. These alternatively spliced messages have been detected using reverse-transcriptase polymerase chain reaction (RT/PCR) amplification in HTLV-I-transformed T cell lines as well as in peripheral blood mononuclear cells (PBMC) from infected patients with and without disease. To gain insight into the role of these alternatively spliced mRNAs in pathogenesis, we developed a semi-quantitative non-PCR-based RNase protection assay to detect and quantitate their presence in HTLV-I-infected cells. Analysis of RNA from HTLV-I-infected cells established from patients with adult T cell leukemia (ATL) as well as tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) and both IL-2-dependent and IL-2-independent HTLV-I-infected cell lines by RNase protection has confirmed the existence of all of the alternatively spliced messages in each cell line analyzed. However, the relative quantity of each message was significantly different among these lines suggesting that splice site utilization is an important viral regulatory pathway.

Adult↗
PubMed1997

The simian T-lymphotropic/leukemia virus from Pan paniscus belongs to the type 2 family and infects Asian macaques.

The proviral DNA of the simian T-leukemia/lymphotropic virus (STLV) isolate, originally obtained from a captive colony of pygmy chimpanzees (Pan paniscus) (STLV(pan-p)), was cloned from the DNA of the chronically infected human T-cell line L93-79B. The entire proviral DNA sequence was obtained and compared with sequences of the known genotypes of STLV and human T-leukemia/lymphotropic virus types 1 and 2 (HTLV-1 and -2). Phylogenetic analysis indicates that STLV-2(pan-p) is an early divergence within the type 2 lineage and should be referred to as STLV-2(pan-p). Since STLV-2(pan-p) has been found in African nonhuman primates, we investigated its infectiousness and pathogenicity in Asian monkeys. Pigtailed macaques were inoculated with human cells harboring STLV(pan-p), and infection was assessed by virus isolation, PCR analysis of peripheral blood mononuclear cells, and seroconversion against viral antigens in HTLV-1/HTLV-2 and Western blot assay. Pigtailed macaques became persistently infected by STLV-2(pan-p), and the virus could be transferred by blood transfusion from an infected pigtailed macaque to a rhesus macaque. In addition, like HTLV-1 and HTLV-2, STLV-2(pan-p) was infectious in rabbits. In summary, STLV-2(pan-p) is a novel retrovirus distantly related to HTLV-2 and displays a host range similar to that demonstrated for other HTLV and STLV strains.

Amino Acid Sequence↗
PubMed1996

p53 functional impairment and high p21waf1/cip1 expression in human T-cell lymphotropic/leukemia virus type I-transformed T cells.

Human T-cell lymphotropic/leukemia virus type I (HTLV-I) is associated with T-cell transformation both in vivo and in vitro. Although some of the mechanisms responsible for transformation remain unknown, increasing evidence supports a direct role of viral as well as dysregulated cellular proteins in transformation. We investigated the potential role of the tumor suppressor gene p53 and of the p53-regulated gene, p21waf1/cip1 (wild-type p53 activated fragment 1/cycling dependent kinases [cdks] interacting protein 1), in HTLV-I-infected T cells. We have found that the majority of HTLV-I-infected T cells have the wild-type p53 gene. However, its function in HTLV-I-transformed cells appears to be impaired, as shown by the lack of appropriate p53-mediated responses to ionizing radiation (IR). Interestingly, the expression of the p53 inducible gene, p21waf1/cip1, is elevated at the messenger ribonucleic acid and protein levels in all HTLV-I-infected T-cell lines examined as well as in Taxl-1, a human T-cell line stably expressing Tax. Additionally, Tax induces upregulation of a p21waf1/cip1 promoter-driven luciferase gene in p53 null cells, and increases p21waf1/cip1 expression in Jurkat T cells. These findings suggest that the Tax protein is at least partially responsible for the p53-independent expression of p21waf1/cip1 in HTLV-I-infected cells. Dysregulation of p53 and p21waf1/cip1 proteins regulating cell-cycle progression, may represent an important step in HTLV-I-induced T-cell transformation.

Base Sequence↗
PubMed1996

Prevalence of HTLV type I infection in Iran: a serological and genetic study.

Several publications describe the presence of the human T cell lymphotropic virus type I (HTLV-I) in Jewish individuals born in Mash-had, Iran. We report here the results of HTLV-I serological and genetic studies in the non-Jewish population of Mash-had as well as a neighboring area: Gonbad-Kavous. Seven hundred and seven serum samples from Mash-had (694 healthy individuals and 13 patients with lymphoma) and 90 from Gonbad-Kavous were tested for HTLV antibodies by gelatin particle agglutination assay (PA) and confirmatory Western blots (WBs). Seropositive rates of 3.0% (21 of 694) in Mash-had, 0% (0 of 90) in Gonbad-Kavous, and 100% (13 of 13) in lymphoma cases were observed. HTLV-I DNA sequence were amplified by polymerase chain reaction directly from the fresh PBMCs of seropositive individuals. Phylogenetic analysis of the viral DNA sequence indicated that the HTLV-I present in Mash-had belong to the HTLV-I cosmopolitan clade. Altogether, these data indicate that Mash-had, located in northeastern Iran, is a newly recognized endemic center for HTLV-I.

Amino Acid Sequence↗
PubMed1996

Multiple immunizations with attenuated poxvirus HIV type 2 recombinants and subunit boosts required for protection of rhesus macaques.

Vaccine protocols involving multiple immunizations with molecularly attenuated vaccinia virus (NYVAC) or naturally attenuated canarypox virus (ALVAC) HIV-2 recombinants and subunit boosts have conferred longlasting protection against HIV-2 infection of macaques. Similar complex protocols using HIV-1 NYVAC and ALVAC recombinants and subunit boosts have provided cross-protection against HIV-2 challenge. Here a simplified three-immunization regimen over 24 weeks was tested in 18 juvenile rhesus macaques. Twelve macaques were immunized twice with NYVAC or ALVAC recombinants carrying HIV-2 env, gag, and pol genes. Subsequently, macaques in groups of three received either an additional recombinant immunization or an HIV-2 gp160 boost. Six control macaques received three immunizations of NYVAC or ALVAC vector alone and additionally alum at the third immunization. Macaques primed with ALVAC recombinant exhibited sporadic T cell proliferative activity, and all but one failed to develop neutralizing antibodies. In contrast, macaques primed with NYVAC recombinants had no T cell proliferative activity but exhibited neutralizing antibody titers (highest in the three recombinant group) that declined by the time of challenge. None of the macaques exhibited significant cytotoxic T lymphocyte activity. Following challenge at 32 weeks with HIV-2SBL6669 all macaques became infected. Thus, the three-immunization regimen is not sufficient to confer protective immunity in the HIV-2 rhesus macaque model. However, delayed infection in macaques immunized with the NYVAC-HIV-2 recombinant may have been associated with the development of memory B cells capable of providing a neutralizing antibody response on challenge.

AIDS Vaccines↗
PubMed1996

Immunogenicity and protective efficacy of a human immunodeficiency virus type 2 recombinant canarypox (ALVAC) vaccine candidate in cynomolgus monkeys.

The efficacy of a recombinant human immunodeficiency virus (HIV) type 2 canarypox (ALVAC HIV-2) vaccine candidate given alone or in combination with HIV-2 envelope gp125 or HIV-2 V3 synthetic peptides was investigated in 14 cynomolgus monkeys. High antibody titers to HIV-2 gp125 were demonstrated in monkeys given booster immunizations with gp125. Neutralizing antibody titers were low (< or = 20) in all monkeys except 2. Significant lymphocyte proliferative responses to killed HIV-2 virions were observed in monkeys given booster immunizations with gp125. HIV-2-specific cytotoxic T lymphocytes were demonstrated prior to viral challenge in 3 of 12 monkeys. After challenge with homologous cell-free HIV-2 propagated in monkey cells, 4 of 10 monkeys immunized with ALVAC HIV-2 plus HIV-2 gp125 or V3 peptides were protected, as determined by negative virus isolation and polymerase chain reaction for viral DNA. Four monkeys immunized with ALVAC HIV-2 alone were not protected. All 12 control monkeys became infected. There was no correlation between the immunologic parameters studied and protection against infection in the vaccinated monkeys.

AIDS Vaccines↗
PubMed1996

Medical students as patients: a pilot study of their health care needs, practices, and concerns.

BACKGROUND: The personal health experiences of medical students may contribute in important but previously unacknowledged ways to their well-being and education. This pilot study surveyed medical students about their health care needs, practices, insurance status, and concerns about seeking care. METHOD: A questionnaire was developed and distributed to 151 students at the University of New Mexico School of Medicine in 1993-94. Participant privacy was protected. Responses were compiled and analyzed using logistic regression models and odds ratios. RESULTS: A total of 112 students responded. Most reported health care needs and half routinely received care at their training institution. One-third had informally requested prescriptions or diagnostic tests from medical school faculty and housestaff; one-fourth used such informal consultation as their "usual" method of obtaining care. Eighteen students were uninsured. The students reported that they had not sought care for several reasons, and many had experienced difficulty in obtaining care. The students indicated concern about confidentiality and about the dual role as both student and patient at the training institution. They believed that their academic standing would be jeopardized if they developed certain health problems. When asked about hypothetical scenarios, a majority preferred to avoid the dual role of medical-student-patient. When asked about scenarios in which medical student peers exhibited suicidal depression or severe drug abuse, the students overwhelmingly preferred not to notify the medical school administration. Significant differences in responses were found with respect to gender and training level. CONCLUSION: This pilot study examined the health care needs, practices (including the use of informal consultation), insurance status, and concerns of students at one medical school. The findings highlight the students' perceptions of illness and vulnerability during medical school training. Constructive implications for academic medicine are discussed regarding initiatives in the areas of policy, research, and the resources and structure of student health care services.

Adult↗