Biomedical subjects

A Battistini

Publications and source records attributed to A Battistini.

At least 19 recordsLinked to original sources

PubMed2006

IRF-1 deficiency skews the differentiation of dendritic cells toward plasmacytoid and tolerogenic features.

Members of the IFN regulatory factors (IRFs) family are transcriptional regulators that play essential roles in the homeostasis and function of the immune system. Recent studies indicate a direct involvement of some members of the family in the development of different subsets of dendritic cells (DC). Here, we report that IRF-1 is a potent modulator of the development and functional maturation of DC. IRF-1-deficient mice (IRF-1(-/-)) exhibited a predominance of plasmacytoid DC and a selective reduction of conventional DC, especially the CD8alpha(+) subset. IRF-1(-/-) splenic DC were markedly impaired in their ability to produce proinflammatory cytokines such as IL-12. By contrast, they expressed high levels of IL-10, TGF-beta, and the tolerogenic enzyme indoleamine 2,3 dioxygenase. As a consequence, IRF-1(-/-) DC were unable to undergo full maturation and retained plasmacytoid and tolerogenic characteristics following virus infection ex vivo and in vivo. Accordingly, DC from IRF-1(-/-) mice were less efficient in stimulating the proliferation of allogeneic T cells and instead, induced an IL-10-mediated, suppressive activity in allogeneic CD4(+)CD25(+) regulatory T cells. Together, these results indicate that IRF-1 is a key regulator of DC differentiation and maturation, exerting a variety of effects on the functional activation and tolerogenic potential of these cells.

Animals↗

PubMed2004

Impaired myelopoiesis in mice devoid of interferon regulatory factor 1.

Interferon regulatory factor (IRF)-1 is a transcription factor controlling the expression of several genes, which are differentially induced depending on the cell type and signal. IRF-1 modulates multiple functions, including regulation of immune responses and host defence, cell growth, cytokine signalling and hematopoietic development. Here, we investigated the role of IRF-1 in granulocytic differentiation in mice with a null mutation in the IRF-1 gene. We show that IRF-1(-/-) bone marrow cells exhibit an increased number of immature granulocytic precursors, associated with a decreased number of mature granulocytic elements as compared to normal mice, suggestive of a defective maturation process. Clonogenetic analyses revealed a reduced number of CFU-G, CFU-M and CFU-GM colonies in IRF-1(-/-) mice, while the number of BFU-E/CFU-E colonies was unchanged. At the molecular level, the expression of CAAT-enhancer-binding protein (C/EBP)-epsilon, -alpha and PU.1 was substantially lower in the CD11b(+) cells from the bone marrow of IRF-1(-/-) mice as compared to cells from wild-type mice. These results, together with the fact that IRF-1 is markedly induced early during granulo-monocytic differentiation of CD34+ cells, highlight the pivotal role of IRF-1 in the early phases of myelopoiesis.

Animals↗

PubMed2002

IRF regulation of HIV-1 long terminal repeat activity.

Interferon (IFN) regulatory factors (IRF) constitute a family of transcriptional activators and repressors implicated in multiple biologic processes, including regulation of immune responses and host defense, cytokine signalling, cell growth regulation, and hematopoietic development. All members are characterized by well-conserved DNA binding domains at the N-terminal region that recognize similar DNA sequences termed IRF-binding element/IFN-stimulated response element (IRF-E/ISRE) present on the promoter of the IFN-alpha/beta genes and of some IFN-stimulated genes (ISG). Recently, a sequence homologous to the ISRE has been identified downstream of the 5' human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR). This sequence is a binding site for IRF-1 and IRF-2. Deletion of the LTR-ISRE results in impaired LTR promoter activity and decreased synthesis of viral RNA and proteins. Here, we briefly summarize characteristics of IRF-1 and IRF-2 binding to the HIV-1 LTR-ISRE and the data obtained to date on the functionality of this cis-element and on the role of IRF in the regulation of HIV-1 LTR transcriptional activity.

Base Sequence↗

PubMed2001

Ectopic expression of interferon regulatory factor-1 potentiates granulocytic differentiation.

Numerous transcription factors allow haematopoietic cells to respond to lineage- and stage-specific cytokines and to act as their effectors. It is increasingly evident that the interferon regulatory factor-1 (IRF-1) transcription factor can selectively regulate different sets of genes depending on the cell type and/or the nature of cellular stimuli, evoking distinct responses in each. In the present study, we investigated mechanisms underlying the differentiation-inducing properties of granulocytic colony-stimulating factor (G-CSF) and whether IRF transcription factors are functionally relevant in myeloid differentiation. Both normal human progenitors and murine 32Dcl3 myeloblasts induced to differentiate along the granulocytic pathway showed an up-regulation of IRF-1 expression. Ectopic expression of IRF-1 did not abrogate the growth factor requirement of 32Dcl3 cells, although a small percentage of cells that survived cytokine deprivation differentiated fully to neutrophils. Moreover, in the presence of G-CSF, granulocytic differentiation of IRF-1-expressing cells was accelerated, as assessed by morphology and expression of specific differentiation markers. Down-modulation of c-Myb protein and direct stimulation of lysozyme promoter activity by IRF-1 were also observed. Conversely, constitutive expression of IRF-2, a repressor of IRF-1 transcriptional activity, completely abrogated the G-CSF-induced neutrophilic maturation. We conclude that IRF-1 exerts a pivotal role in granulocytic differentiation and that its induction by G-CSF represents a limiting step in the early events of differentiation.

Adult↗

PubMed2001

HHV-8 encoded vIRF-1 represses the interferon antiviral response by blocking IRF-3 recruitment of the CBP/p300 coactivators.

Human herpes virus 8 (HHV-8) has developed unique mechanisms for altering cellular proliferative and apoptotic control pathways by incorporating viral homologs to several cellular regulatory genes into its genome. One of the important pirated genes encoded by the ORF K9 reading frame is a viral homolog of the interferon regulatory factors (IRF), a family of cellular transcription proteins that regulates expression of genes involved in pathogen response, immune modulation and cell proliferation. vIRF-1 has been shown to downregulate the interferon- and IRF-mediated transcriptional activation of ISG and murine IFNA4 gene promoters. In this study we demonstrate that vIRF-1 efficiently inhibited virus-induced expression of endogenous interferon B, CC chemokine RANTES and CXC chemokine IP-10 genes. Co-expression analysis revealed that vIRF-1 selectively blocked IRF-3 but not IRF-7-mediated transactivation. vIRF-1 was able to bind to both IRF-3 and IRF-7 in vivo as detected by coimmunoprecipitation analysis, but did not affect IRF-3 dimerization, nuclear translocation and DNA binding activity. Rather, vIRF-1 interacted with the CBP/p300 coactivators and efficiently inhibited the formation of transcriptionally competent IRF-3-CBP/p300 complexes. These results illustrate that vIRF-1 is able to block the early stages of the IFN response to virus infection by interfering with the activation of IRF-3 responsive, immediate early IFN genes.

Antiviral Agents↗

PubMed2001

Six-minute walking test in cystic fibrosis adults with mild to moderate lung disease: comparison to healthy subjects.

The six-minute walking test (6MWT) has been widely utilized to evaluate global exercise capacity in patients with cystic fibrosis. The aim of this study was to assess the exercise capacity by 6MWT, measuring four outcome measures: walk distance, oxygensaturation and pulse rate during the walk, and breathlessness perception after the walk, in a group of cystic fibrosis adults with mild to moderate lung disease, and in healthy volunteers, as the control group. Moreover, the study examined the relationship between 6MWT outcome measures and pulmonary function in patients. Twenty-five adults (15 females, age range 18-39 years) with cystic fibrosis and 22 healthy volunteers (14 females, age range 20-45 years) performed a 6MWT following a standard protocol. Walk distance, oxygen saturation (SpO2) and pulse rate at rest and during walk, and breathlessness perception after walk assessed by visual analogue scale (VAS) were measured. Cystic fibrosis patients did notdiffer from healthy volunteers in walk distance (626 +/- 49 m vs. 652 +/- 46 m) and pulse rate. Patients significantly differed from healthy volunteers in SPO2 during the walk (mean SpO2) (P < 0.0001) and VAS (P < 0.0001). In patients, SPO2 during the walk significantly correlated with forced expiratory volume in 1 sec (FEV1) (P < 0.0001), residual volume (RV) (P < 0.001), resting SPO2 (base SpO2) (P < 0.001), and inspiratory capacity (IC) (P < 0.01). In addition, VAS significantly correlated with resting SPO2 (P < 0.01) and IC (P < 0.01). On the basis of regression equations by stepwise multiple regression analysis, SpO2 during walk was predicted by FEV1 (r2 = 0.60) and VAS by IC (r2 = 0.31), whereas walk distance was not reliably predicted by any assessed variables. This study showed that cystic fibrosis adults with mild to moderate lung disease covered a normal walk distance with unimpaired cardiac adaptation, but experienced a significant fall in oxygen saturation and an increased breathlessness perception during exercise. Resting pulmonary function was related to oxygen saturation and breathlessness perception during walk, but contributed significantly only tothe prediction of oxygen saturation. We suggest that 6MWT could be valuable for identifying patients who might experience oxygen desaturation and dyspnoea during demanding daily activities.

Adolescent↗

PubMed2001

Interferon-gamma receptor 2 expression as the deciding factor in human T, B, and myeloid cell proliferation or death.

The heterodimeric interferon (IFN)-gamma receptor (IFN-gammaR) is formed of two chains. Here we show that the binding chain (IFN-gammaR1) was highly expressed on the membranes of T, B, and myeloid cells. Conversely, the transducing chain (IFN-gammaR2) was highly expressed on the surfaces of myeloid cells, moderately expressed on B cells, and poorly expressed on the surfaces of T cells. Differential cell membrane expression of IFN-gammaR2 determined the number of receptor complexes that transduced the IFN-gamma signal and resulted in a different response to IFN-gamma. After IFN-gamma stimulation, high IFN-gammaR2 membrane expression induced rapid activation of signal transducer and activator of transcription-1 (STAT-1) and high levels of interferon regulatory factor-1 (IRF-1), which then triggered the apoptotic program. By contrast, low cell membrane expression resulted in slow activation of STAT-1, lower levels of IRF-1, and induction of proliferation. Because the forced expression of IFN-gammaR2 on T cells switched their response to IFN-gamma from proliferative to apoptotic, we concluded that the surface expression of IFN-gammaR2 determines whether a cell stimulated by IFN-gamma undergoes proliferation or apoptosis.

Apoptosis↗

PubMed2000

IFN-gamma and IL-4 differently regulate inducible NO synthase gene expression through IRF-1 modulation.

NO is a labile radical involved in several immunological, antimicrobial and inflammatory processes. In macrophages, NO formation is catalyzed by the cytokine-inducible enzyme inducible NO synthase (iNOS). The importance of IFN regulatory factor (IRF)-1 and of the signal transducers and activators of transcription (STAT)-1 for the induction of iNOS gene expression in response to IFN-gamma has been well defined. Here, we investigated the molecular events responsible for the inhibition of iNOS gene expression by IL-4 in the murine macrophage cell line RAW264.7. Unidirectional deletion analysis on iNOS promoter demonstrated that an IFN-stimulated responsive element (ISRE), contained in the -980 to -765 bp region of the iNOS promoter, may be involved in the IL-4-mediated inhibition of IFN-gamma-inducible iNOS transcription. Accordingly, the IFN-gamma-induced binding activity of IRF-1 to the ISRE sequence was reduced in cells pre-treated with IL-4, while the binding activity of STAT-1 to the STAT-binding element (SBE) within the same region of the iNOS promoter remained unaffected. Moreover, IL-4 even down-regulated IFN-gamma-inducible expression of IRF-1 mRNA. This could be related to a transcriptional mechanism by which IL-4 and IFN-gamma differentially influence the trans-acting activity of the STAT factors binding to SBE within the IRF-1 promoter. SBE is targeted by IFN-gamma-inducible STAT-1 and by IL-4-inducible STAT-6. Although STAT-6 has no trans-acting function on iNOS gene expression, it is able to inhibit the IFN-gamma-induced expression of IRF-1. Thus, IL-4 may down-regulate IFN-gamma-inducible iNOS transcription by activation of STAT-6 which in turn inhibits IRF-1 expression.

Animals↗

PubMed2000

[The pediatrician facing the problem of polluted air].

The enormous amount of data concerning outdoor pollution has allowed quantifying the damage caused by single pollutants. On the basis of these data, and knowing the concentration of a pollutant in a given area, to date it is possible to foresee the expected risk for a given disease in our community. For instance, in an average size town like Parma, it can be calculated that in the middle of the winter, suspended particulate pollution (PM10), one day/three, will increase by 30% the number of symptomatic asthmatic children. In the long term, in a town like Parma, PM10 and NO2 pollution increases the number of children with more than 4 episodes of bronchitis or persistent cough by 30-50%. With regard to the typical summer pollution by O3, extremely harmful as it expands outside towns, in Parma and surroundings in August one should expect in 1/3 days double the number of symptomatic asthmatic patients, and every other day a 25% reduction of the respiratory function in asthmatic children exercising. With regard to indoor pollution besides the well known and severe problem of passive smoking, and that of volatile organic compounds still under investigation, one must consider NO2 pollution originating from the burning processes for heating and cooking. As this latter is extremely important in Italy, as gas is used in practically every house, the Author has done a specific research in which it is shown that if this kind of pollution was eliminated one could reduce the incidence of asthma in childhood from 7 to 5%, and noticeably the severity of the disease in affected subjects. Thus, paediatricians have two new aims. The first is to identify in pollution one of the possible causes of respiratory problems in each single patient, giving recommendations (ex. advise asthmatic children to avoid physical activity in the open and in the sunny hours during the summer, or avoid having children in the kitchen while cooking, or have boilers, heaters, etc. checked). Second, paediatricians should make aware, using the local actual data on pollution, not only the local administrators, but also and may be more important the parents of children with respiratory problems. These are in fact the ones who can and must become the most active in facing the big problem of pollution.

Air Pollution↗

PubMed2000

[Thirty years of activity at the center for cystic fibrosis in Parma].

One hundred fourteen patients (52 males, age range 1 to 40 yr, median age 16 yr) affected by Cystic Fibrosis (CF) are currently followed by the CF Centre of Parma. Forty two percent of them are adults. Most patients live in Emilia Romagna (59%) and Lombardia (19%). With respect to CF genotype, delta F508 mutation has been found in 54% of patients. Despite of the improvement in knowledge of CF, its diagnosis is still based on the clinical features and sweat test is usually used to confirm the diagnosis. Recent diagnostic tools, such as the genetic analysis and the potential difference measurement, could also be helpful in ambiguous situations. In the CF Centre of Parma, in agreement with the literature, the disease is now diagnosed earlier than in the past. Particularly, in the last year the median age of diagnosis was seven months, while it was 20 months in the 1980s. The early diagnosis and the improvement in the treatment of lung disease has significantly increased the median survival age of our patients, changing from 7.5 years in 1975 to 20 years in 1999. A significant improvement in CF prognosis could be further achieved by potential investigational agents, such as "protein-repair" addressed to CFTR activation. However, the gold standard for CF therapy is represented by gene therapy, although it is not yet available.

Adolescent↗

PubMed1999

Expression of wild-type and V210I mutant prion protein in human neuroblastoma cells.

The conversion of the host-encoded prion protein (PrPc) into the insoluble, protease-resistant isoform (PrPsc) is the main pathogenic mechanism of transmissible spongiform encephalopathies. They are fatal neurodegenerative disorders, which in human occur as sporadic, inherited or familial forms. These last forms are linked to insert or point mutations of PrPc which may facilitate the spontaneous conversion into PrPsc. We have established stably transfected human neuroblastoma cells (SH-SY5Y) expressing mutant V210I, or wild-type PrPc. Both proteins were expressed and attached to the cell surface. The mutation in position 210 did not alter the biochemical properties of the protein in comparison with the wild-type protein nor induced any conformational changes similar to those observed in PrPsc.

Amino Acid Substitution↗

PubMed1999

Activation and repression of the 2-5A synthetase and p21 gene promoters by IRF-1 and IRF-2.

The Interferon Regulatory Factors-1 and -2 (IRF-1 and IRF-2) were originally identified as transcriptional regulators of the interferon (IFN) and IFN-stimulated genes. These factors also modulate immune response and play a role in cell growth regulation. In this study we analysed the effect of the ectopic expression of IRF-1 and IRF-2 on the regulation of two potential IRF target genes involved in cell growth regulation, 2-5A synthetase and p21 (WAF/CP1), both of which contain consensus binding sites for IRF family members within their promoters. Following ectopic expression, IRF-1 transactivated 2-5A synthetase and p21 genes, an effect that was counterbalanced by concomitant ectopic expression of IRF-2. These effects were mediated by direct binding of IRF to the gene promoters. A construct expressing an IRF-2 antisense (FRI-2) was able to revert the inhibitory effect of IRF-2 on the IRF-1 transactivation. IRF-1 also induced expression of its homologous repressor IRF-2 as indicated by EMSA analysis using an IRF-E probe from the IRF-2 promoter; and by cotransfection of IRF-1 together with an IRF-2 promoter CAT construct. Therefore, the induction of IRF-1 by IFNs or other stimuli acts as a transactivator of genes involved in cell growth regulation, as well as of its own repressor IRF-2, thus providing autoinhibitory regulation of IRF-1 activated genes.

2',5'-Oligoadenylate Synthetase↗

PubMed1999

Interleukin-12 induces expression of interferon regulatory factor-1 via signal transducer and activator of transcription-4 in human T helper type 1 cells.

IRF-1-deficient mice show a striking defect in the development of T helper 1 (Th1) cells. In the present report, we investigate the expression of IRF-1 during differentiation of human T helper cells. No significant differences of IRF-1 mRNA expression were found in established Th1 and Th2 cells; however, interleukin 12 (IL-12) induced a strong up-regulation of IRF-1 transcripts in Th1 but not in Th2 cells. We demonstrate that IL-12-induced up-regulation of IRF-1 is mediated by signal transducer and activator of transcription-4, which binds to the interferon (IFN)-gamma-activated sequence present in the promoter of the IRF-1 gene. Strong IL-12-dependent activation of a reporter gene construct containing the IRF-1 IFN-gamma-activated sequence element provides further evidence for the key role of signal transducer and activator of transcription-4 in the IL-12-induced up-regulation of IRF-1 transcripts in T cells. IRF-1 expression was strongly induced after stimulation of naive CD4(+) T cells via the T cell receptor, irrespective of the cytokines present at priming, indicating that this transcription factor does not play a major role in initiating a Th1-specific transcriptional cascade in differentiating helper T cells. However, our finding that IRF-1 is a target gene of IL-12 suggests that some of the IL-12-induced effector functions of Th1 cells may be mediated by IRF-1.

Activating Transcription Factor 4↗

PubMed1999

The activity of the CCAAT-box binding factor NF-Y is modulated through the regulated expression of its A subunit during monocyte to macrophage differentiation: regulation of tissue-specific genes through a ubiquitous transcription factor.

In this study, we analyzed the regulation of NF-Y expression during human monocyte to macrophage maturation. NF-Y is a ubiquitous and evolutionarily conserved transcription factor that binds specifically to the CCAAT motif present in the 5' promoter region of a wide variety of genes. We show here that in circulating monocytes, NF-Y binding activity is not detected on the CCAAT motif present in the promoters of genes such as major histocompatibility complex (MHC) class II, gp91-phox, mig, and fibronectin, whereas during macrophage differentiation, a progressive increase in NF-Y binding activity is observed on these promoters. Analysis of NF-Y subunit expression indicates that the absence of NF-Y activity in circulating monocytes is caused by a lack of the A subunit. Furthermore, addition of the recombinant NF-YA subunit restores NF-Y binding. We show that the lack of NF-YA protein is due to posttranscriptional regulation and not to a specific proteolytic activity. In fact, NF-YA mRNA is present at the same level at all days of monocyte cultivation, whereas the protein is absent in freshly isolated monocytes but is progressively synthesized during the maturation process. We thus conclude that the NF-YA subunit plays a relevant role in activating transcription of genes highly expressed in mature monocytes. In line with this conclusion, we show that the cut/CDP protein, a transcriptional repressor that inhibits gpc91-phox gene expression by preventing NF-Y binding to the CAAT box, is absent in monocytes.

CCAAT-Enhancer-Binding Proteins↗

PubMed1999

STAT1 activation during monocyte to macrophage maturation: role of adhesion molecules.

Human monocytes isolated from peripheral blood of healthy donors show a time-dependent differentiation into macrophages upon in vitro cultivation, closely mimicking their in vivo migration and maturation into extravascular tissues. The mediator(s) of this maturation process has not been yet defined. We investigated the involvement of signal transducers and activators of transcription (STAT) factors in this phenomenon and reported the specific, time-dependent, activation of STAT1 protein starting at day 0/1 of cultivation and maximally expressed at day 5. STAT1 activity was evident on the STAT binding sequences (SBE) present in the promoters of genes which are up-regulated during monocyte to macrophage maturation such as FcgammaRI and ICAM-1, and in the promoter of the transcription factor IFN regulatory factor-1. Moreover, the effect of cell adhesion to fibronectin or laminin was studied to investigate mechanisms involved in STAT1 activation. Compared with monocytes adherent on plastic surfaces, freshly isolated cells allowed to adhere either to fibronectin- or laminin-coated flasks exhibited an increased STAT1 binding activity both in control and in IFN-gamma-treated cells. The molecular events leading to enhanced STAT1 activation and cytokine responsiveness concerned both Y701 and S727 STAT1 phosphorylation. Exogenous addition of transforming growth factor-beta, which exerts an inhibitory effect on some monocytic differentiation markers, inhibited macrophage maturation, integrin expression and STAT1 binding activity. Taken together these results indicate that STAT1 plays a pivotal role in the differentiation/maturation process of monocytes as an early transcription factor initially activated by adherence and then able to modulate the expression of functional genes, such as ICAM-1 and FcgammaRI.

Adolescent↗

PubMed1998

Synergistic stimulation of MHC class I and IRF-1 gene expression by IFN-gamma and TNF-alpha in oligodendrocytes.

In order to understand the molecular basis of the synergistic action of interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) on rat oligodendrocyte development, we studied some aspects of the signalling pathways involved in the regulation of the major histocompatibility complex (MHC) class I and the interferon regulatory factor 1 (IRF-1) gene expression. Two well-defined inducible enhancers of the MHC class I gene promoter, the MHC class I regulatory element (MHC-CRE) and the interferon consensus sequence (ICS), were analysed. Neither IFN-gamma nor TNF-alpha was capable of inducing MHC-CRE binding activity when administrated alone. Following the exposure of oligodendrocytes to IFN-gamma, TNF-R1 expression was transcriptionally induced by the binding of signal transducer and activator of transcription (STAT-1) homodimers to the IFN-gamma activated site (GAS) present in the gene promoter. The upregulation of TNF-R1 allowed TNF-alpha to induce the binding of nuclear factor-kappaB (NF-kappaB) to the MHC-CRE site. With respect to ICS element, IFN-gamma induced IRF-1 binding, that was further enhanced upon co-treatment with TNF-alpha. The existence of a synergism between IFN-gamma and TNF-alpha in stimulating IRF-1 expression at the transcriptional level was supported by IRF-1 promoter analysis: IFN-gamma directly induced the binding of STAT-1 homodimers to the GAS element, while NF-kappaB binding to the kappaB sequence was activated by TNF-alpha only after IFN-gamma treatment. This transcriptional regulation of IRF-1 gene by IFN-gamma and TNF-alpha was confirmed at the mRNA level. The synergism demonstrated in the present study highlights the importance of cytokine interactions in magnifying their biological effects during brain injury and inflammation.

Animals↗

PubMed1997

Regulation of expression of ferritin H-chain and transferrin receptor by protoporphyrin IX.

The effect of protoporphyrin IX (hemin without iron) on the expression of transferrin receptor and ferritin was investigated in Friend leukemia cells. Cells treated with protoporphyrin IX exhibit enhanced transferrin-receptor expression and markedly reduced ferritin synthesis. Stimulation of transferrin-receptor expression is observed at both the mRNA and protein level. The effect on ferritin synthesis is mediated by translational inhibition of the mRNA, which, in contrast, is transcriptionally stimulated by protoporphyrin IX treatment. The regulation of transferrin receptor and ferritin in response to iron perturbations has been studied extensively and is mediated by the binding of iron-regulatory proteins (IRP) to the iron-responsive elements (IRE) present in the 3' and 5' untranslated regions of the transferrin-receptor and ferritin mRNA, respectively. To elucidate the molecular mechanisms underlying the effects of protoporphyrin IX on ferritin and transferrin-receptor expression, the role of the IRE sequence was investigated both in vivo by transfection experiments, with a construct containing the coding region for the chloramphenicol acetyltransferase (CAT) reporter gene under the translational control of the ferritin IRE, and in vitro by RNA band-shift assays. Whereas, examination of IRP binding to the IRE by in vitro assays suggests an apparent inactivation of IRP by protoporphyrin IX treatment, CAT assays indicate that protoporphyrin IX is able to induce in vivo a translational inhibition similar to that obtained by treatment with the iron chelator Desferal. This observation raises the possibility of different effects on the IRP activity exerted by porphyrin treatment in intact tissue-culture cells and in vitro. We conclude that translation of ferritin mRNA and degradation of transferrin-receptor mRNA are inhibited in intact tissue-culture cells by protoporphyrin IX through a mechanism similar to that exerted by iron chelation, thus involving depletion of the intracellular iron pool. These results can improve the understanding of the regulation of ferritin gene expression in some pathological conditions associated with disturbed heme synthesis.

Animals↗

PubMed1997

Faecal elastase 1 in children with cystic fibrosis.

UNLABELLED: Recently, a new ELISA kit for determination of elastase 1 in faeces has become commercially available. Studies in patients with chronic pancreatitis have indicated that it is a simple and sensitive test of exocrine pancreatic function. The aim of this study was to assess the clinical value of this new test in cystic fibrosis. A total of 72 children were studied: 27 who were healthy, 22 with cystic fibrosis and 23 with non-pancreatic disorders. Oral pancreatic extracts were not discontinued in the children with cystic fibrosis. A small sample of faeces was collected from each subject for elastase 1 concentration and chymotrypsin activity determination. In all of the healthy children and most of those with non-pancreatic disorders (20/23), elastase 1 concentrations were greater than 500 microg/g; in contrast, the vast majority (20/22) of children with cystic fibrosis had very low values (less than 20 microg/g). The differences between children with cystic fibrosis and the other two groups were highly significant (P < 0.001). With a cut-off level of 132 microg/g, the sensitivity and specificity of faecal elastase 1 for the determination of exocrine pancreatic insufficiency were 96% and 100%, respectively. The specificity of faecal chymotrypsin was 96%, but its sensitivity was not calculated since the children with cystic fibrosis continued to take pancreatic extracts during the study. CONCLUSION: The determination of faecal elastase 1 concentration is a simple and reliable means of assessing exocrine pancreatic function in children with cystic fibrosis. Results are not influenced by non-pancreatic disorders or by enzyme supplementation.

Adolescent↗