PubMed Health⌕ Search

Biomedical subjects

G Bossi

Publications and source records attributed to G Bossi.

At least 19 recordsLinked to original sources
PubMed2006

Novel Munc13-4 mutations in children and young adult patients with haemophagocytic lymphohistiocytosis.

Familial haemophagocytic lymphohistiocytosis (FHL) is a genetically heterogeneous disorder characterised by constitutive defects in cellular cytotoxicity resulting in fever, hepatosplenomegaly and cytopenia, and the outcome is fatal unless treated by chemoimmunotherapy followed by haematopoietic stem-cell transplantation. Since 1999, mutations in the perforin gene giving rise to this disease have been identified; however, these account only for 40% of cases. Lack of a genetic marker hampers the diagnosis, suitability for transplantation, selection of familial donors, identification of carriers, genetic counselling and prenatal diagnosis. Mutations in the Munc13-4 gene have recently been described in patients with FHL. We sequenced the Munc13-4 gene in all patients with haemophagocytic lymphohistiocytosis not due to PRF1 mutations. In 15 of the 30 families studied, 12 novel and 4 known Munc13-4 mutations were found, spread throughout the gene. Among novel mutations, 2650C-->T introduced a stop codon; 441del A, 532del C, 3082del C and 3226ins G caused a frameshift, and seven were mis sense mutations. Median age of diagnosis was 4 months, but six patients developed the disease after 5 years of age and one as a young adult of 18 years. Involvement of central nervous system was present in 9 of 15 patients, activity of natural killer cells was markedly reduced or absent in 13 of 13 tested patients. Chemo-immunotherapy was effective in all patients. Munc13-4 mutations were found in 15 of 30 patients with FHL without PRF1 mutations. Because these patients may develop the disease during adolescence or even later, haematologists should include FHL2 and FHL3 in the differential diagnosis of young adults with fever, cytopenia, splenomegaly and hypercytokinaemia.

Adolescent↗
PubMed2006

Mutant p53 gain of function: reduction of tumor malignancy of human cancer cell lines through abrogation of mutant p53 expression.

Mutations in the TP53 tumor suppressor gene are the most frequent genetic alteration in human cancers. These alterations are mostly missense point mutations that cluster in the DNA binding domain. There is growing evidence that many of these mutations generate mutant p53 proteins that have acquired new biochemical and biological properties. Through this gain of function activity, mutant p53 is believed to contribute to tumor malignancy. The purpose of our study was to explore mutant p53 as a target for novel anticancer treatments. To this aim, we inhibited mutant p53 expression by RNA interference in three different cancer cell lines endogenously expressing mutant p53 proteins, and evaluated the effects on the biological activities through which mutant p53 exerts gain of function. We found that depletion of mutant p53 reduces cell proliferation, in vitro and in vivo tumorigenicity, and resistance to anticancer drugs. Our results demonstrate that mutant p53 knocking down weakens the aggressiveness of human cancer cells, and provides further insight into the comprehension of mutant p53 gain of function activity in human tumor.

Animals↗
PubMed2001

Echocardiographic evaluation of patients cured of childhood cancer: a single center study of 117 subjects who received anthracyclines.

BACKGROUND: The risk of cardiomyopathy following exposure to anthracycline in asymptomatic long-term survivors of childhood cancer is still hard to predict and precisely quantify. To identify the impact of different cumulative doses, even within a non-high dose range, and the echocardiographic parameters suitable for evaluating cardiac function, we studied diastolic and systolic echocardiographic parameters in a cohort of patients followed in a single center. PROCEDURE: A total of 117 subjects were studied at a median time of 7 years after treatment completion. A complete M-mode, two-dimensional and Doppler echocardiographic study was obtained at rest in all patients according to the standard recommendations of the American Society of Echocardiography. RESULTS: Ninety-nine patients (85%) had completely normal cardiac function, while 18 had abnormal echocardiographic findings: 12 had one abnormal value, 5 had two, and 1 had three abnormal values. All the changes were in left ventricular dimensions, wall thickness or indices of systolic function; no alterations in left ventricular diastolic function parameters were found. None of the echocardiographic parameters correlated significantly with the cumulative dose of anthracyclines administered either at univariate analysis or after adjusting for sex, body surface area or considered risk factors. CONCLUSIONS: Subjects exposed to a median cumulative dose of 214 mg/m(2) had no echographic abnormalities a median of 7 years later. We did not find any correlation between cumulative anthracycline dose and the echocardiographic parameters tested. We now offer echocardiographic follow-up to patients with mildly reduced fractional shortening and/or ejection fraction to rule out late onset dysfunction.

Antibiotics, Antineoplastic↗
PubMed2001

The immunological synapse of CTL contains a secretory domain and membrane bridges.

Cytotoxic T lymphocytes (CTL) rapidly destroy their targets. Here we show that although target cell death occurs within 5 min of CTL-target cell contact, an immunological synapse similar to that seen in CD4 cells rapidly forms in CTL, with a ring of adhesion proteins surrounding an inner signaling molecule domain. Lytic granule secretion occurs in a separate domain within the adhesion ring, maintaining signaling protein organization during exocytosis. Live and fixed cell studies show target cell plasma membrane markers are transferred to the CTL as the cells separate. Electron microscopy reveals continuities forming membrane bridges between the CTL and target cell membranes, suggesting a possible mechanism for this transfer.

Animals↗
PubMed2001

Neonatal screening program for congenital adrenal hyperplasia: adjustments to the recall protocol.

OBJECTIVE: To evaluate the influence of gestational age (GA) and birth weight (BW) on 17 alpha-OH-progesterone (17-OHP) levels with respect to their impact on the recall rate of neonatal screening programs for congenital adrenal hyperplasia (CAH). PATIENTS AND METHODS: In June 1997 we began a pilot screening program for CAH measuring 17-OHP using a fluoroimmunoassay method (DELFIA) on dried blood spots. Until September 1999, 24,153 babies were screened. Among them, we analyzed the levels of 17-OHP in 1,313 samples from healthy preterm babies (23-36 weeks) and 1,500 term babies (>37 weeks), grouped according to GA and BW. All preterm babies underwent another sampling in their 2nd week of life. RESULTS: 5 CAHs were detected. The 30-nmol/l cutoff limit for 17-OHP in blood corresponded to the calculated 99th percentile in term newborns, while in preterm babies higher levels were found. GA and BW correlated inversely with 17-OHP levels. CONCLUSION: GA and BW were useful tools to adjust cutoff levels, obtaining a significant reduction in follow-up testing and psychological stress for families. The high false-positive recall rate in preterm babies can be substantially lowered with adjusted GA and/or BW criteria.

17-alpha-Hydroxyprogesterone↗
PubMed2001

Fas ligand is targeted to secretory lysosomes via a proline-rich domain in its cytoplasmic tail.

Fas ligand (FasL) induces apoptosis through its cell surface receptor Fas. T lymphocytes and natural killer cells sort newly synthesised FasL to secretory lysosomes but, in cell types with conventional lysosomes, FasL appears directly on the plasma membrane. Here, we define a proline-rich domain (PRD) in the cytoplasmic tail of FasL that is responsible for sorting FasL to secretory lysosomes. Deletion of this PRD results in cell surface expression of FasL in cells with secretory lysosomes. Positively charged residues flanking the PRD are crucial to the sorting motif and changing the charge of these residues causes mis-sorting to the plasma membrane. In cells with conventional lysosomes, this motif is not recognised and FasL is expressed at the plasma membrane. The FasL PRD is not required for endocytosis in any cell type, as deletion mutants lacking this motif are endocytosed efficiently to the lysosomal compartment. Endogenous FasL cannot internalise extracellular antibody, demonstrating that FasL does not transit the plasma membrane en route to the secretory lysosomes. We propose that an interaction of the PRD of FasL with an SH3-domain-containing protein, enables direct sorting of FasL from the Golgi to secretory lysosomes.

Amino Acid Sequence↗
PubMed2000

Cooperative transformation of 32D cells by the combined expression of IRS-1 and V-Ha-Ras.

32D cells expressing v-Ha-Ras fail to show a transformed phenotype. Since Ras requires an active IGF-1R for transformation of fibroblasts, we asked whether expression of IRS-1 or Shc (two of the major substrates of the IGF-1R) could co-operate with oncogenic Ras in transforming 32D cells. We find that IRS-1, but not Shc, in combination with v-Ha-Ras generates a fully transformed phenotype in 32D cells. 32D cells expressing both IRS-1 and v-Ha-Ras (32D/IRS1/Ras) survive and proliferate in the absence of IL-3, do not undergo granulocytic differentiation in the presence of G-CSF and form tumors in nu/nu and syngeneic mice. In contrast, 32D cells expressing singly IRS-1 or v-Ha-Ras exhibit only a block in differentiation capacity. Over-expression of Shc proteins, by itself, promotes differentiation of 32D cells. Concomitant expression of IRS-1 and v-Ha-Ras synergistically phosphorylates ERK-1 and ERK-2 whereas a MEK inhibitor rapidly induces death of 32D/IRS1/Ras transformed cells. Furthermore, transformed 32D/IRS1/Ras cells display high levels of PI3-K activation and undergo rapid apoptosis when exposed to PI3-K inhibitors. The data indicate that: (1) a fully transformed phenotype in 32D cells is generated when a block in differentiation (v-Ha-Ras) is coupled with another differentiation block (IRS-1); (2) PI3-K and MAPK activity are required for the survival of transformed cells; (3) the signals generated by IRS-1 and oncogenic Ras converge on ERK and PI3-K resulting in high levels of activation.

Androstadienes↗
PubMed2000

Integrin LFA-1 interacts with the transcriptional co-activator JAB1 to modulate AP-1 activity.

Integrin adhesion receptors transduce signals that control complex cell functions which require the regulation of gene expression, such as proliferation, differentiation and survival. Their intracellular domain has no catalytic function, indicating that interaction with other transducing molecules is crucial for integrin-mediated signalling. Here we have identified a protein that interacts with the cytoplasmic domain of the beta2 subunit of the alphaL/beta2 integrin LFA-1. This protein is JAB1 (Jun activation domain-binding protein 1), a coactivator of the c-Jun transcription factor. We found that JAB1 is present both in the nucleus and in the cytoplasm of cells and that a fraction of JAB1 colocalizes with LFA-1 at the cell membrane. LFA-1 engagement is followed by an increase of the nuclear pool of JAB1, paralleled by enhanced binding of c-Jun-containing AP-1 complexes to their DNA consensus site and increased transactivation of an AP-1-dependent promoter. We suggest that signalling through the LFA-1 integrin may affect c-Jun-driven transcription by regulating JAB1 nuclear localization. This represents a new pathway for integrin-dependent modulation of gene expression.

Animals↗
PubMed2000

Development of a murine orthotopic model of leukemia: evaluation of TP53 gene therapy efficacy.

The onco-suppressor gene TP53 has potential use in the gene therapy of many human cancers including leukemias. The latter indication derived from numerous experimental reports of p53-mediated suppressing effects on human and murine leukemia cells in vitro. However, few in vivo experiments have been performed, and those that have used a subcutaneous injection of p53-transduced leukemia cells. Thus, we developed an orthotopic leukemia model in adult, syngenic mice to evaluate the feasibility of TP53-mediated therapeutic approaches. We found that among other cells, v-src-transformed 32D myeloid progenitors induce leukemia when injected intravenously in syngenic mice. The resulting malignancy resembles the clinical manifestations of human acute myeloid leukemia because it is characterized by a massive invasion of bone marrow compartments, splenomegaly, generalized lymphadenopathy, and a macroscopic or microscopic infiltration of the kidneys, liver, and lungs. When these 32Dv-src cells were infected with a TP53-recombinant retrovirus before intravenous injection, we found a decreased mortality and, in those animals that develop leukemia, a drastic reduction of the generalized organ infiltration, suggesting that exogenous TP53 expression might be used for ex vivo bone marrow purging from leukemia cells.

Animals↗
PubMed2000

Expression of eotaxin, interleukin 13 and tumour necrosis factor-alpha in dermatitis herpetiformis.

BACKGROUND: The dermal and perivascular infiltrate in dermatitis herpetiformis (DH), which is mainly composed of CD4+ lymphocytes, neutrophils and eosinophils, is believed to play an important part in the pathogenesis of the disease. Previous studies suggest that cytokines such as interleukin (IL) -8, granulocyte-macrophage colony-stimulating factor, IL-4 and IL-5 could be involved in the pathogenesis of DH. These cytokines appear to drive tissue infiltration and maturation of eosinophils. Part of the effect of T-helper (Th) 2-type cytokines (IL-4, IL-5) on eosinophils could be mediated by eotaxin, which is a highly specific chemotactic protein induced by various cytokines [IL-4, IL-13, tumour necrosis factor (TNF) -alpha and interferon-gamma]. OBJECTIVES: To evaluate the expression of eotaxin and its inducers, IL-13 and TNF-alpha, in DH. METHODS We examined lesions collected from 10 DH patients with active disease. Sections from each specimen were incubated with anti-IL-13, anti-TNF-alpha and anti-eotaxin antibodies. Chloroacetyl esterase reaction was performed to show mast cell infiltration. RESULTS: Eotaxin was mainly expressed at the tips of the dermal papillae, within the microabscesses. Positivity was also found in the lymphomonocytic infiltrate in the dermis. IL-13 was expressed in the dermal infiltrate and TNF-alpha was found in the inflammatory infiltrate and in dermal vascular cells. CONCLUSIONS: These findings confirm the importance of the lymphomonocytic infiltrate and of Th2 cytokines in the pathogenesis of this disease, suggesting that tissue infiltration in DH is mediated by cell-specific chemokines such as eotaxin and not only by non-specific chemokines such as IL-8.

Adult↗
PubMed2000

Cytogenetic abnormalities in PHA-stimulated lymphocytes from patients with Langerhans cell histocytosis. AIEOP-Istiocitosi Group.

The aetiopathogenesis of Langerhans cell histiocytosis (LCH) is still undefined. Constitutional abnormalities in LCH have rarely been reported. One study showed chromosomal instability in lesional cells from three patients. No chromosomal studies are available on peripheral blood lymphocytes. Peripheral blood lymphocytes were analysed for the presence of chromatid and/or chromosomal breaks and structural rearrangements. A fluorescence in situ hybridization (FISH) painting technique was also applied in two cases. Sixteen patients with multisystem (MS, n = 11) or single system (SS, n = 5) LCH were studied. either at the diagnosis (n = 8), during treatment (n = 2) or during follow-up, when asymptomatic (n = 6). Thirteen patients had chromosomal abnormalities. Eleven patients (69%) had chromatid and chromosomal breaks in 7-45% of cells. Overall, chromosome and chromatid breaks were significantly more frequent in the 11 patients with MS disease than in the five patients with SS disease: the mean percentage of cells showing chromosome and chromatid breaks was 13.4% in MS patients vs. 6.2% in SS patients (P = 0.003). Chromosomal abnormalities may be found in phytohaemagglutinin (PHA)-stimulated peripheral blood lymphocytes of LCH patients at diagnosis, during the disease course and even during long-term follow-up, more frequently in MS disease. Chromosome instability may be considered as either a basic genetic instability or as a landmark of reaction to an environmental agent (viral?) that, through genome alteration, may play a role in histiocyte proliferation and, in some cases, also in the increased risk of malignancy.

Adult↗
PubMed2000

Lack of clinically significant cardiac dysfunction during intermediate dobutamine doses in long-term childhood cancer survivors exposed to anthracyclines.

BACKGROUND: Long-term survivors of childhood cancer treated with anthracyclines may have subclinical cardiac dysfunction undetectable at a baseline evaluation. Dobutamine stress echocardiography has been proposed as a more sensitive screening test, but results of previous studies were influenced by selection criteria, infusion protocols, and side effects. METHODS: We applied a modified dobutamine stress test (from 5 to 10 to 15 microg/kg, infused over a 5-minute period) and evaluated the influence on stress test results of reported risk factors for late cardiac toxicity (female sex, younger age at treatment, higher dose of anthracycline, and longer duration of follow-up). Seventy-one patients (46 male, mean age 15 +/- 5 years) treated with anthracyclines (median dose 240 mg/m(2)) 1 to 16.5 years before and 20 controls (patients' siblings: 12 male, mean age 19 +/- 4 years) were studied. RESULTS: No major side effects were recorded. One patient was unable to perform the test because of anxiety. Limiting side effects were infrequent (3%) and occurred at a dobutamine dose of > or =10 microg/kg, when significant changes of hemodynamic and echocardiographic parameters were detectable in all cases. Rest systolic and mean blood pressure and left ventricular fractional shortening were significantly lower in patients than in controls (P <.05), but no differences were found in any of the other indexes of cardiac function between the 2 groups at rest and during each dobutamine infusion step. A similar increase of global left ventricular function (percent of fractional shortening +45% vs +32%) and a decrease of end-systolic stress (-33% vs -29%) were documented. Left ventricular relaxation, early filling, and both relaxation and compliance improved. In all but one patient with reduced global left ventricular function at baseline, time-dependent patterns of hemodynamic and echocardiographic responses to dobutamine were similar. Previously described risk factors for cardiac toxicity did not influence the time changes of the echocardiographic parameters in response to dobutamine. CONCLUSIONS: Compared with controls, most of our asymptomatic childhood cancer survivors, studied an average of 7 years after treatment with anthracyclines, showed normal baseline cardiac function. Our stress test was feasible and safe. Compared with modalities used in other studies, shorter infusion periods with higher dobutamine doses allowed a higher stress intensity to be reached without reducing patient compliance. At dobutamine stress test the response was comparable in patients and controls except for one patient. Previously reported risk factors for cardiac toxicity had no significant influence on stress test results.

Adolescent↗
PubMed2000

Sorting out the multiple roles of Fas ligand.

Fas ligand can both be used by the immune system to initiate cell death, and be used by non-lymphoid cells to evade death. Recent work has shown that Fas ligand is differentially sorted in different cell types. Here we present the viewpoint that the differential sorting plays an important part in determining the role of Fas ligand in different cells.

Animals↗