Biomedical subjects

Antonio Rossi

Publications and source records attributed to Antonio Rossi.

At least 19 recordsLinked to original sources

PubMed2007

Identification of genes displaying differential expression in the nuc-2 mutant strain of the mold Neurospora crassa grown under phosphate starvation.

Subtractive hybridization was used to isolate transcripts up-regulated in the nuc-2 mutant strain of Neurospora crassa grown under phosphate starvation. Following differential screening, 66 cDNA clones of the total enriched were screened in a second round by reverse Northern hybridization. The 17 cDNA candidates displaying visual positive differential expression were sequenced, and functional grouping identified putative proteins possibly involved in diverse cellular processes as, for example, protein synthesis, signal transduction mechanisms, and transport facilitation. Four of them, confirmed by both virtual and Northern blot analyses, revealed genes involved in the initiation of mRNA translation that are significantly up-regulated in the nuc-2 mutant strain, which may be relevant to a further understanding of the molecular events involved in the phosphorus sensing in N. crassa.

Ankyrin Repeat↗

PubMed2006

Human recombinant prolidase from eukaryotic and prokaryotic sources. Expression, purification, characterization and long-term stability studies.

Prolidase is a Mn(2+)-dependent dipeptidase that cleaves imidodipeptides containing C-terminal proline or hydroxyproline. In humans, a lack of prolidase activity causes prolidase deficiency, a rare autosomal recessive disease, characterized by a wide range of clinical outcomes, including severe skin lesions, mental retardation, and infections of the respiratory tract. In this study, recombinant prolidase was produced as a fusion protein with an N-terminal histidine tag in eukaryotic and prokaryotic hosts and purified in a single step using immobilized metal affinity chromatography. The enzyme was characterized in terms of activity against different substrates, in the presence of various bivalent ions, in the presence of the strong inhibitor Cbz-Pro, and at different temperatures and pHs. The recombinant enzyme with and without a tag showed properties mainly indistinguishable from those of the native prolidase from fibroblast lysate. The protein yield was higher from the prokaryotic source, and a detailed long-term stability study of this enzyme at 37 degrees C was therefore undertaken. For this analysis, an 'on-column' digestion of the N-terminal His tag by Factor Xa was performed. A positive effect of Mn(2+) and GSH in the incubation mixture and high stability of the untagged enzyme are reported. Poly(ethylene glycol) and glycerol had a stabilizing effect, the latter being the more effective. In addition, no significant degradation was detected after up to 6 days of incubation with cellular lysate. Generation of the prolidase in Escherichia coli, because of its high yield, stability, and similarity to native prolidase, appears to be the best approach for future structural studies and enzyme replacement therapy.

Animals↗

PubMed2006

In vivo contribution of amino acid sulfur to cartilage proteoglycan sulfation.

Cytoplasmic sulfate for sulfation reactions may be derived either from extracellular fluids or from catabolism of sulfur-containing amino acids and other thiols. In vitro studies have pointed out the potential relevance of sulfur-containing amino acids as sources for sulfation when extracellular sulfate concentration is low or when its transport is impaired such as in DTDST [DTD (diastrophic dysplasia) sulfate transporter] chondrodysplasias. In the present study, we have considered the contribution of cysteine and cysteine derivatives to in vivo macromolecular sulfation of cartilage by using the mouse model of DTD we have recently generated [Forlino, Piazza, Tiveron, Della Torre, Tatangelo, Bonafe, Gualeni, Romano, Pecora, Superti-Furga et al. (2005) Hum. Mol. Genet. 14, 859-871]. By intraperitoneal injection of [35S]cysteine in wild-type and mutant mice and determination of the specific activity of the chondroitin 4-sulfated disaccharide in cartilage, we demonstrated that the pathway by which sulfate is recruited from the intracellular oxidation of thiols is active in vivo. To check whether cysteine derivatives play a role, sulfation of cartilage proteoglycans was measured after treatment for 1 week of newborn mutant and wild-type mice with hypodermic NAC (N-acetyl-L-cysteine). The relative amount of sulfated disaccharides increased in mutant mice treated with NAC compared with the placebo group, indicating an increase in proteoglycan sulfation due to NAC catabolism, although pharmacokinetic studies demonstrated that the drug was rapidly removed from the bloodstream. In conclusion, cysteine contribution to cartilage proteoglycan sulfation in vivo is minimal under physiological conditions even if extracellular sulfate availability is low; however, the contribution of thiols to sulfation becomes significant by increasing their plasma concentration.

Acetylcysteine↗

PubMed2006

Targeting the heat shock factor 1 by RNA interference: a potent tool to enhance hyperthermochemotherapy efficacy in cervical cancer.

Carcinoma of the uterine cervix is one of the highest causes of mortality in female cancer patients worldwide, and improved treatment options for this type of malignancy are highly needed. Local hyperthermia has been successfully used in combination with systemic administration of cisplatin-based chemotherapy in phase I/II clinical studies. Heat-induced expression of cytoprotective and antiapoptotic heat shock proteins (HSP) is a known complication of hyperthermia, resulting in thermotolerance and chemoresistance and hindering the efficacy of the combination therapy. Heat shock transcription factor 1 (HSF1) is the master regulator of heat-induced HSP expression. In the present report, we used small interfering RNA (siRNA) to silence HSF1 and to examine the effect of HSF1 loss of function on the response to hyperthermia and cisplatin-based chemotherapy in HeLa cervical carcinoma. We have identified the 322-nucleotide to 340-nucleotide HSF1 sequence as an ideal target for siRNA-mediated HSF1 silencing, have created a pSUPER-HSF1 vector able to potently suppress the HSF1 gene, and have generated for the first time human cancer cell lines with stable loss of HSF1 function. We report that, although it surprisingly does not affect cancer cell sensitivity to cisplatin or elevated temperatures up to 43 degrees C when administered separately, loss of HSF1 function causes a dramatic increase in sensitivity to hyperthermochemotherapy, leading to massive (>95%) apoptosis of cancer cells. These findings indicate that disruption of HSF1-induced cytoprotection during hyperthermochemotherapy may represent a powerful strategy to selectively amplify the damage in cancer cells and identify HSF1 as a promising therapeutic target in cervical carcinoma.

Apoptosis↗

PubMed2006

Cetuximab in advanced non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) remains a major problem in the western civilization and developing countries. Since most patients with NSCLC have advanced disease at diagnosis, to date, chemotherapy, with third-generation platinum-based doublets, represents the standard of care. Advances in the knowledge of tumour biology and mechanisms of oncogenesis has granted the singling out of several molecular targets for NSCLC treatment. Epidermal growth factor receptor (EGFR), a member of ErbB family, is one of the most studied target. Cetuximab is a chimeric (human-murine) monoclonal antibody directed against the extracellular domain of the EGFR that blocks ligand (TGF-alpha, EGF) access to the receptor. In the present paper we discuss about the activity, tolerability and efficacy of cetuximab, the EGFR monoclonal blocking antibody with the largest amount of clinical data being available on the treatment of advanced NSCLC.

Antibodies, Monoclonal↗

PubMed2006

Collagen plays an active role in the aggregation of beta2-microglobulin under physiopathological conditions of dialysis-related amyloidosis.

Dialysis-related amyloidosis is characterized by the deposition of insoluble fibrils of beta(2)-microglobulin (beta(2)-m) in the musculoskeletal system. Atomic force microscopy inspection of ex vivo amyloid material reveals the presence of bundles of fibrils often associated to collagen fibrils. Aggregation experiments were undertaken in vitro with the aim of reproducing the physiopathological fibrillation process. To this purpose, atomic force microscopy, fluorescence techniques, and NMR were employed. We found that in temperature and pH conditions similar to those occurring in periarticular tissues in the presence of flogistic processes, beta(2)-m fibrillogenesis takes place in the presence of fibrillar collagen, whereas no fibrils are obtained without collagen. Moreover, the morphology of beta(2)-m fibrils obtained in vitro in the presence of collagen is extremely similar to that observed in the ex vivo sample. This result indicates that collagen plays a crucial role in beta(2)-m amyloid deposition under physiopathological conditions and suggests an explanation for the strict specificity of dialysis-related amyloidosis for the tissues of the skeletal system. We hypothesize that positively charged regions along the collagen fiber could play a direct role in beta(2)-m fibrillogenesis. This hypothesis is sustained by aggregation experiments performed by replacing collagen with a poly-L-lysine-coated mica surface. As shown by NMR measurements, no similar process occurs when poly-L-lysine is dissolved in solution with beta(2)-m. Overall, the findings are consistent with the estimates resulting from a simplified collagen model whereby electrostatic effects can lead to high local concentrations of oppositely charged species, such as beta(2)-m, that decay on moving away from the fiber surface.

Amyloid↗

PubMed2006

Self-aggregation of fibrillar collagens I and II involves lysine side chains.

Several properties of fibrillar collagens depend on abundance and position of ionic amino acids. We recently demonstrated that N-methylation and N-acetylation of Lys/Hyl amino group did not significantly alter the thermal stability of the triple helical conformation and that the binding of modified collagens I and II to decorin is lost only on N-acetylation. The positive charge at physiological pH of Lys/Hyl side chains is preserved only by N-methylation. We report here the new aspect of the influence of the same modifications on collagen self-aggregation in neutral conditions. Three collagen preparations are very differently affected by N-methylation: acid-soluble type I collagen maintains the ability to form banded fibrils with 67-nm periodicity, whereas almost no structured aggregates were detected for pepsin-soluble type I collagen; pepsin-soluble type II collagen forms a very different supramolecular species, known as segment long spacing (SLS). N-acetylation blocks the formation of banded fibrils in neutral conditions (as did all other chemical modifications reported in the literature), demonstrating that the positive charge of Lys/Hyl amino groups is essential for self-aggregation. Kinetic measurements by turbidimetry showed a sizeable increase of absorbance only for the two N-methylated samples forming specific supramolecular aggregates; however, the derivatization affects aggregation kinetics by increasing lag time and decreasing maximum slope of absorbance variation, and lowers aggregation competency. We discuss that the effects of N-methylation on self-aggregation are caused by fewer or weaker salt bridges and by decrease of hydrogen bonding potential and conclude that protonated Lys side chains are involved in the fibril formation process.

Acetylation↗

PubMed2006

Herpes simplex virus disrupts NF-kappaB regulation by blocking its recruitment on the IkappaBalpha promoter and directing the factor on viral genes.

Herpes simplex viruses (HSVs) are able to hijack the host-cell IkappaB kinase (IKK)/NF-kappaB pathway, which regulates critical cell functions from apoptosis to inflammatory responses; however, the molecular mechanisms involved and the outcome of the signaling dysregulation on the host-virus interaction are mostly unknown. Here we show that in human keratinocytes HSV-1 attains a sophisticated control of the IKK/NF-kappaB pathway, inducing two distinct temporally controlled waves of IKK activity and disrupting the NF-kappaB autoregulatory mechanism. Using chromatin immunoprecipitation we demonstrate that dysregulation of the NF-kappaB-response is mediated by a virus-induced block of NF-kappaB recruitment to the promoter of the IkappaBalpha gene, encoding the main NF-kappaB-inhibitor. We also show that HSV-1 redirects NF-kappaB recruitment to the promoter of ICP0, an immediate-early viral gene with a key role in promoting virus replication. The results reveal a new level of control of cellular functions by invading viruses and suggest that persistent NF-kappaB activation in HSV-1-infected cells, rather than being a host response to the virus, may play a positive role in promoting efficient viral replication.

Blotting, Western↗

PubMed2006

Compliance with therapy in hypertensive patients.

OBJECTIVE: This study investigated pharmacological compliance in hypertensive patients recruited during a 24-month period at the Hypertension Clinic of the S. Maria Nuova Hospital. METHODS: The compliance profile scale was developed in order to classify compliance as sufficient, or poor. Compliance was evaluated according to patients' (1) global cardiovascular risk (hypertensive) and (2) complexity of prescribed treatment at enrolment (drug, number of pills). RESULTS: A total of 367 patients were recruited; 82 were excluded owing to changes in therapeutic schedule or medication necessitated by other medical or surgical disease. Compliance was evaluated in 285 patients, 66% were male; the mean age was 72 +/- 12 years. Compliance was evaluated at a series of follow-ups at 3-month intervals and at 36 months of observation. Compliance at 36 months was good or sufficient in 56% of patients, but differed according to hypertensive and drug status. Compliance was better in patients with a higher level vs. lower level of hypertension severity. Specifically, compliance was better in hypertensives with co-morbidity (76%) than in hypertensives without co-morbidity (37%) or hypertensives with risk factors (65%). Moreover, compliance was better in patients with a more complex therapeutic regimen (drug 1 through 3: 47, 59 and 66%). CONCLUSIONS: These data demonstrate a relationship between disease severity and compliance, independent of the prescribed therapeutic regimen. This suggests that the most important factor for therapy adherence is disease awareness and severity, and patients with a higher level of disease are more likely to be compliant.

Adolescent↗

PubMed2006

The pH signaling transcription factor PacC mediates the growth of Trichophyton rubrum on human nail in vitro.

We report here the isolation, molecular cloning and initial characterization of the Trichophytonrubrum pacC gene, which encodes a putative protein that is homologous to the PacC/Rim101p family of pH signaling transcription regulators. The promoter region of the T. rubrumpacC gene contains four recognition sites 5'-GCCAAG-3' for the PacC protein, suggesting that the transcription of this gene itself could be induced under alkaline growth conditions. The enhanced expression profile of the T. rubrumpacC gene in an alkaline environment was confirmed by Northern blotting analysis. We also report that the disruption of pacC gene decreased both the secretion of keratinolytic proteases and the ability of the mutant pacC-1 to grow on human nail fragments as the sole source of nutrition, i.e., growth of the dermatophyte T. rubrum appear to be related to molecular events which depend on the action of protein PacC.

Amino Acid Sequence↗

PubMed2006

Treatment of stage I-III non-small-cell lung cancer in the elderly.

Elderly patients with stage I-III non-small-cell lung cancer (NSCLC) constitute a peculiar patient population and need specific therapeutic approaches. Limited resections are an attractive alternative for elderly patients with resectable NSCLC because of the potential reduction in postoperative complications. Curative radiation therapy is an acceptable alternative for elderly patients who are unfit for or refuse surgery. Hypofractionated stereotactic body radiation therapy is of particular interest for this population because of its favorable tolerance. Elderly patients may tolerate chemotherapy poorly because of comorbidity and organ failure. The survival benefit obtained with adjuvant platinum-based chemotherapy in the younger population may vanish or decrease in the elderly because of a potential higher toxic death rate or lower compliance to treatment. The efficacy and feasibility of adjuvant chemotherapy for elderly patients need to be investigated in specific trials. Neoadjuvant chemotherapy remains an experimental approach under investigation in the general patient population, and consequently should not be considered in clinical practice in the elderly. Retrospective analyses on chemoradiation in elderly patients should be considered globally ambiguous and at risk of selection bias. Only specifically designed prospective studies will elucidate the real role and feasibility of this combined approach in the treatment of unselected elderly patients.

Age Factors↗

PubMed2006

Insights from a transgenic mouse model on the role of SLC26A2 in health and disease.

Mutations in the SLC26A2 cause a family of recessive chondrodysplasias that includes in order of decreasing severity achondrogenesis 1B, atelosteogenesis 2, diastrophic dysplasia and recessive multiple epiphyseal dysplasia. The gene encodes for a widely distributed sulfate/chloride antiporter of the cell membrane whose function is crucial for the uptake of inorganic sulfate that is needed for proteoglycan sulfation. To investigate the mechanisms leading to skeletal dysplasia, we generated a transgenic mouse with a mutation in Slc26a2 causing a partial loss of function of the sulfate transporter. Homozygous mutant mice were characterized by skeletal dysplasia with chondrocytes of irregular size, delay in the formation of the secondary ossification centre and osteoporosis of long bones. Impaired sulfate uptake was demonstrated in chondrocytes, osteoblasts and fibroblasts, but proteoglycan undersulfation was detected only in cartilage. The similarity with human diastrophic dysplasia makes this mouse a model to explore pathogenetic and therapeutic aspects of SLC26A2-related disorders.

Animals↗

PubMed2005

Pretreatment quality of life and functional status assessment significantly predict survival of elderly patients with advanced non-small-cell lung cancer receiving chemotherapy: a prognostic analysis of the multicenter Italian lung cancer in the elderly study.

PURPOSE: To study the prognostic value for overall survival of baseline assessment of functional status, comorbidity, and quality of life (QoL) in elderly patients with advanced non-small-cell lung cancer treated with chemotherapy. PATIENTS AND METHODS: Data from 566 patients enrolled onto the phase III randomized Multicenter Italian Lung Cancer in the Elderly Study (MILES) study were analyzed. Functional status was measured as activities of daily living (ADL) and instrumental ADL (IADL). The presence of comorbidity was assessed with a checklist of 33 items; items 29 and 30 of the European Organisation for Research and Treatment of Cancer (EORTC) core questionnaire QLQ-C30 (EORTC QLQ-C30) were used to estimate QoL. ADL was dichotomized as none versus one or more dependency. For IADL and QoL, three categories were defined using first and third quartiles as cut points. Comorbidity was summarized using the Charlson scale. Analysis was performed by Cox model, and stratified by treatment arm. RESULTS: Better values of baseline QoL (P = .0003) and IADL (P = .04) were significantly associated with better prognosis, whereas ADL (P = .44) and Charlson score (P = .66) had no prognostic value. Performance status 2 (P = .006) and a higher number of metastatic sites (P = .02) also predicted shorter overall survival. CONCLUSIONS: Pretreatment global QoL and IADL scores, but not ADL and comorbidity, have significant prognostic value for survival of elderly patients with advanced non-small-cell lung cancer who were treated with chemotherapy. Using these scores in clinical practice might improve prognostic prediction for treatment planning.

Activities of Daily Living↗

PubMed2005

Screening for lung cancer: New horizons?

Lung cancer remains the leading cause of cancer-related deaths in the world. At present, the only high rate of cure therapy is surgical resection at early stage of disease. Early detection could potentially decrease lung cancer mortality suggesting that this cancer should be a good candidate for screening. Results of trials involving chest X-ray, sputum cytology and low-dose computed tomography (CT) are discussed here. The latter tool offers advantages over chest X-ray, but final results from controlled well conducted trials are necessary before the real utility of CT mass screening can be determined. Further approaches to secondary prevention such as screening with positron emission tomography (PET), autofluorescence bronchoscopy and biomarkers hold great promise for the future.

Age Factors↗

PubMed2005

N-benzyloxycarbonyl-L-proline: an in vitro and in vivo inhibitor of prolidase.

Prolidase deficiency (PD) is a recessive disorder of the connective tissue caused by mutations in the prolidase, a specific peptidase, cleaving the dipeptides with a C-terminal prolyl and hydroxyprolyl residue. PD is a complex syndrome characterized mainly by intractable skin lesions, recurrent respiratory infections and mental retardation. The relation between prolidase biological functions and the disease is still largely unknown. We studied the effect of a prolidase inhibitor, N-benzyloxycarbonyl-l-proline (Cbz-Pro), in vitro on prolidase from human fibroblasts and in vivo on murine erythrocytes prolidase. A 90% inhibition was detected incubating cellular extracts at 1:1 ratio of Gly-Pro substrate: Cbz-Pro inhibitor. Pulse experiments performed incubating human fibroblasts with 6 mM Cbz-Pro revealed that the inhibitor uptake was completed in about 1 min. The Cbz-Pro uptake was saturable and pH dependent. Long-term incubation of fibroblasts with Cbz-Pro caused mitochondria depolarization and increased cellular death as reported for long-term culture of fibroblasts from PD patients. An inhibitory effect of Cbz-Pro has also been shown in vivo. Our results demonstrated that Cbz-Pro is a potent inhibitor of prolidase in cultured fibroblasts and it can be used in vivo to better characterize the prolidase enzyme and further investigate PD physiopathology.

Animals↗

PubMed2005

A diastrophic dysplasia sulfate transporter (SLC26A2) mutant mouse: morphological and biochemical characterization of the resulting chondrodysplasia phenotype.

Mutations in the diastrophic dysplasia sulfate transporter (DTDST or SLC26A2) cause a family of recessively inherited chondrodysplasias including, in order of decreasing severity, achondrogenesis 1B, atelosteogenesis 2, diastrophic dysplasia (DTD) and recessive multiple epiphyseal dysplasia. The gene encodes a widely distributed sulfate/chloride antiporter of the cell membrane whose function is crucial for the uptake of inorganic sulfate, which is needed for proteoglycan sulfation. To provide new insights in the pathogenetic mechanisms leading to skeletal and connective tissue dysplasia and to obtain an in vivo model for therapeutic approaches to DTD, we generated a Dtdst knock-in mouse with a partial loss of function of the sulfate transporter. In addition, the intronic neomycine cassette in the mutant allele contributed to the hypomorphic phenotype by inducing abnormal splicing. Homozygous mutant mice were characterized by growth retardation, skeletal dysplasia and joint contractures, thereby recapitulating essential aspects of the DTD phenotype in man. The skeletal phenotype included reduced toluidine blue staining of cartilage, chondrocytes of irregular size, delay in the formation of the secondary ossification center and osteoporosis of long bones. Impaired sulfate uptake was demonstrated in chondrocytes, osteoblasts and fibroblasts. In spite of the generalized nature of the sulfate uptake defect, significant proteoglycan undersulfation was detected only in cartilage. Chondrocyte proliferation and apoptosis studies suggested that reduced proliferation and/or lack of terminal chondrocyte differentiation might contribute to reduced bone growth. The similarity with human DTD makes this mouse strain a useful model to explore pathogenetic and therapeutic aspects of DTDST-related disorders.

Animals↗

PubMed2005

Beta2-microglobulin isoforms display an heterogeneous affinity for type I collagen.

It has been claimed that beta2-microglobulin (beta2-m) interacts with type I and type II collagen, and this property has been linked to the tissue specificity of the beta2-m amyloid deposits that target the osteo-articular system. The binding parameters of the interaction between collagen and beta2-m were determined by band shift electrophoresis and surface plasma resonance by using bovine collagen of type I and type II and various isoforms of beta2-m. Wild-type beta2-m binds collagen type I with a Kd of 4.1 x 10(-4) M and type II with 2.3 x 10(-3) M. By the BIAcore system we monitored the binding properties of the conformers of the slow phase of folding of beta2-m. The folding intermediates during the slow phase of folding do not display any significant difference with respect to the binding properties of the fully folded molecule. The affinity of beta2-m truncated at the third N-terminal residue does not differ from that reported for the wild-type protein. Increased affinity for collagen type I is found in the case of N-terminal truncated species lacking of six residues. The Kd of this species is 3.4 x 10 (-5) M at pH 7.4 and its affinity increases to 4.9 x 10(-6) M at pH 6.4. Fluctuations of the affinity caused by beta2-m truncation and pH change can cause modifications of protein concentration in the solvent that surrounds the collagen, and could contribute to generate locally a critical protein concentration able to prime the protein aggregation.

Amyloidosis↗

PubMed2005

Analbuminemia in a Swiss family is caused by a C --> T transition at nucleotide 4446 of the albumin gene.

OBJECTIVE: To define the molecular defect that causes analbuminemia in an apparently healthy boy, son of non-consanguineous Swiss parents. DESIGN AND METHODS: Total DNA, extracted from peripheral blood samples from the proband and from both parents, was PCR-amplified using oligonucleotide primers designed to amplify the 14 exons of the human albumin gene and the flanking intron regions. The products were screened for mutations by single-strand conformation polymorphism (SSCP) and heteroduplex analyses (HA) either directly or after digestion with restriction enzymes. The combination of these methods identified the abnormal fragment, which was then sequenced. RESULTS: DNA sequence analysis identified in the homozygous proband a C --> T transition at nucleotide 4446. The mutation changes the codon CGA for Arg 114 to a stop codon TGA, resulting in premature termination and is therefore responsible for the analbuminemic trait. The same mutation has been previously reported to cause analbuminemia in an American female. The putative protein product would have a length of 113 residues. The parents were found to be heterozygous for the mutation. CONCLUSIONS: Gel-based mutation detection and DNA sequencing confirmed the diagnosis of congenital analbuminemia in the proband. Our results show that the combination of SSCP and HA represents a powerful tool to study the molecular defects causing analbuminemia in humans.

Albumins↗