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G Della Porta

Publications and source records attributed to G Della Porta.

At least 19 recordsLinked to original sources
PubMed2006

Corticosteroid microparticles produced by supercritical-assisted atomization: process optimization, product characterization, and "in vitro" performance.

In this work, the production of dexametasone and dexametasone acetate microparticles is proposed using supercritical-assisted atomization (SAA). This process is based on the solubilization of supercritical carbon dioxide in a liquid solution containing the drug; then, the ternary mixture is sprayed through a nozzle and submicroparticles are formed as a consequence of the enhanced atomization. Several process parameters such as different organic solvent (methanol and acetone), solute concentration and flow rate ratio between the liquid solution and carbon dioxide are investigated; their influence is evaluated on the morphology and size of precipitated particles. Spherical corticosteroid particles with mean diameters ranging from 0.5 to 1.2 microm are produced at the optimum operating conditions and narrow particle size distributions (PSDs) have also been obtained. No drug degradation was observed after SAA processing and solvent residues of 300 and 500 ppm for acetone and methanol, respectively, were measured. Drug microparticles produced by SAA can be semi-crystalline or amorphous depending on the process condition; a micronized drug surface area ranging from about 4 to 5 m2/g was also observed. The "in vitro" activity of both untreated and SAA processed glucocorticoids was tested on the release of pro-inflammatory cytokines from stimulated cells. The results shown that SAA-glucocorticoids have retained the activity of the parent untreated compounds and, in the case of dexamethasone, SAA processing improves drug performance.

Adrenal Cortex Hormones↗
PubMed2004

Griseofulvin micronization and dissolution rate improvement by supercritical assisted atomization.

Supercritical assisted atomization (SAA) was used to micronize griseofulvin (GF), selected as a model compound, to verify the performance of this innovative process. SAA is based on the solubilization of supercritical carbon dioxide in a liquid solution containing the drug. The ternary mixture is then sprayed through a nozzle and microparticles are formed as a consequence of the enhanced atomization. Precipitation temperature and drug concentration in the liquid solution were studied to evaluate their influence on morphology and size of precipitated particles. A good particle size control was obtained and GF spherical particles with mean diameters ranging from 0.5 to 2.5 microm were produced with a narrow particle size distribution. Processed GF was characterized by high-performance liquid chromatography-UV/vis, headspace-gas chromatography-flame ionization detection, differential scanning calorimetry, BET and X-ray analyses. No drug degradation was observed and a solvent residue (acetone) less than 800 ppm was measured. GF microparticles showed good stability and surface areas ranging from about 4 to 6 m(2) g(-1); moreover, the micronized drug retained the crystalline habit. GF capsules were formulated with starch and used to compare the dissolution rate of SAA-processed and conventional jet-milled drug. A faster dissolution and a better reproducibility of the dissolution profile were observed for SAA-processed GF.

Antifungal Agents↗
PubMed2003

Terbutaline microparticles suitable for aerosol delivery produced by supercritical assisted atomization.

A new micronization technique called supercritical assisted atomization has been used to produce terbutaline microparticles with controlled particle size distribution in the range of drug particles deliverable by aerosol. The process is based on the solubilization of a fixed amount of supercritical carbon dioxide in a liquid solution; then, the ternary mixture is sprayed through a nozzle and atomized in order to produce microparticles. Water has been used as the liquid solvent; heated nitrogen has also been delivered into the precipitator to evaporate the liquid droplets. The process has been first optimized with respect to pressure and temperature (mixing temperature and pressure, precipitation temperature) and very mild operation conditions have been selected; then, the influence of the solute concentration in the liquid solution on particle size has been studied. The terbutaline produced powders were characterized with respect to morphologies and particle size. Spherical particles with very narrow volumetric particle size distributions were produced. Particularly, operating at 30 and 50mg of terbutaline per ml of water, more than 90% of the two distributions ranged between 1 and 3 microm; at 80 mg/ml more than 99% of the distribution ranged between 1 and 4 microm. HPLC analysis confirmed that no chemical degradation occurred in the drug as a consequence of the supercritical processing.

Aerosols↗
PubMed2003

Ampicillin micronization by supercritical assisted atomization.

The micronization technique called supercritical assisted atomization (SAA) was used to produce ampicillin microparticles with controlled particle size and particle size distribution suitable for aerosol drug delivery. The process is based on the solubilization of supercritical CO2 in a liquid solution. The ternary mixture is then sprayed through a nozzle and, as a consequence of enhanced atomization, solid microparticles are formed. Water and organic solvents were tested with ampicillin to determine the influence of the solvent on the process mechanism. SAA process parameters were studied by testing different supercritical/liquid solvent flow ratios, ampicillin concentrations in the liquid solution and nozzle diameters. The effect of these parameters on morphology, particle size and particle size distribution of microparticles was analysed. Ampicillin particles suitable for aerosol delivery in the size range 1-5 microm were obtained using buffered water. Moreover, by varying the solute concentration, ampicillin particles in a narrower range (1-3 microm) than that usually suggested for aerosol deliverable drugs were obtained. This is an example of particle size tailoring by SAA.

Aerosols↗
PubMed1994

Frequent activation of ret protooncogene by fusion with a new activating gene in papillary thyroid carcinomas.

Tumor specific rearrangements of ret gene are frequently detected in papillary thyroid carcinomas. These rearrangements result in the formation of chimeric genes showing the tyrosine kinase domain of ret fused with the 5' end sequences of different genes. We examined a series of 52 patients and identified 10 cases of ret fusion with D10S170 locus resulting in the generation of ret/PTC1 oncogene, 2 cases with the gene encoding the regulatory subunit RI alpha of PKA (ret/PTC2), and finally 6 cases, here described, with a newly discovered gene called ele1 localized on chromosome 10 and leading to the formation of ret/PTC3 oncogene. Our results show the expression of the ret/PTC3 hybrid gene in all the 6 cases and demonstrated its association with the synthesis of 2 constitutively phosphorylated isoforms of the oncoprotein (p75 and p80). The chromosome 10 localization of both ret and ele1 and the detection, in all cases, of a sequence reciprocal to that generating the oncogenic rearrangements, strongly suggest that ret/PTC3 formation is a consequence of an intrachromosomal inversion of chromosome 10.

3T3 Cells↗
PubMed1994

A t(10;17) translocation creates the RET/PTC2 chimeric transforming sequence in papillary thyroid carcinoma.

Activation of the RET protooncogene tyrosine kinase (tk) by fusion with other genes is a frequent finding in papillary thyroid carcinoma. The tk domain of proto-RET can be fused either with the D10S170 gene generating the RET/PTC1 transforming sequence or with sequences belonging to the gene encoding the regulatory subunit RIA of c-AMP-dependent protein kinase A, thus forming the RET/PTC2 oncogene. We have previously shown that an inversion of chromosome 10, inv(10)(q11.2q21), is responsible for the generation of the RET/PTC1. Here we report that a chromosomal translocation, t(10;17)(q11.2;q23), juxta-poses the tk domain of the RET protooncogene, which resides on chromosome 10, to a 5' portion of the RIA gene on chromosome 17, leading to the formation of the chimeric transforming gene RET/PTC2. The finding of the transforming protein in primary tumor cell extracts supports the conclusion that RET/PTC2 activation plays a role in papillary thyroid tumorigenesis.

3T3 Cells↗
PubMed1994

Inhibition of hepatitis B virus surface antigen gene expression in carcinogen-induced liver tumors from transgenic mice.

We previously showed that hepatitis B surface antigen (HBsAg)-producing transgenic mice were more sensitive to hepatocarcinogens than their normal littermates were. We have now investigated the regulation of hepatitis B virus (HBV) gene expression in carcinogen-induced liver tumors of HBV-carrier transgenic mice and in three cell lines derived from tumor samples. Transcription of the S gene was repressed in 17 tumors even though they had normal levels of liver-specific mRNAs such as albumin and transferrin. Three hepatoma cell lines, derived from independent tumor samples, were analyzed for their capacity to express the S gene after transfection of cloned DNA. Although they no longer expressed the endogenous S gene, they were still able to express it from transfected viral DNA both transiently and stably. The loss of HBsAg expression in tumors and in the cell lines was accompanied by de novo methylation of the S region, which is a way to permanently repress gene expression. Our data confirm in an animal model previous observations of S-gene expression in human hepatocarcinoma and suggest a role for its downregulation in tumor progression.

Animals↗
PubMed1994

Selective activation of ras oncogenes in follicular and undifferentiated thyroid carcinomas.

A total of 96 tumour samples (88 primary tumours and 8 nodal metastases) from 88 patients with thyroid adenomas and carcinomas were investigated for ras gene mutations using polymerase chain reaction, oligonucleotide probing and sequencing. Neither the 19 adenomas nor the 31 papillary carcinomas analysed harboured point mutations. In our cases, mutations in all three ras oncogenes were found in follicular carcinomas (five out of 21) and in the less differentiated thyroid tumour: poorly differentiated carcinomas (three out of 11) and undifferentiated carcinomas (one out of five). Finally, mutated ras oncogenes had a significant association with the appearance of haematogenous (particularly bone) metastases, suggesting a role of ras genes activation in the metastatic capability of these tumours.

Adenocarcinoma, Follicular↗
PubMed1993

Chromosome mapping of murine susceptibility loci to liver carcinogenesis.

The validity of mouse liver tumors is controversial in the risk assessment of carcinogenicity of chemicals in humans, because mice used in carcinogenicity bioassays are genetically predisposed to liver tumors. The argument could be resolved once liver tumor susceptibility genes have been cloned and their role in liver tumor development elucidated. We performed a genetic linkage analysis to map murine liver tumor susceptibility genes, as a first step toward their identification. An F2 population of 87 urethane-treated male A/J x C3H/He mice was scored with 83 genetic markers. Three regions, localized on chromosomes 7, 8, and 12, were found to contain putative liver tumor susceptibility genes.

Animals↗
PubMed1993

11q deletions in human colorectal carcinomas: cytogenetics and restriction fragment length polymorphism analysis.

Deletions and/or allelic losses of a portion of the long arm of chromosome 11 were discovered by cytogenetic and restriction fragment length polymorphism analyses in 23 of 39 (59%) informative cases of colorectal carcinoma. By comparing the patterns of loss of heterozygosity and chromosome rearrangements in different patients, we could map a common target region to 11q22-23. This region may contain a tumor suppressor gene, the inactivation of which may be involved in the development of tumors of the large intestine. The subgroup of malignancies with 11q alterations seemed to be enriched by tumors that were located in the rectum, that were Dukes' stage A, and that were well differentiated and mucin producing.

Adult↗
PubMed1993

A major susceptibility locus to murine lung carcinogenesis maps on chromosome 6.

Lung tumours represent a major cause of death in humans, and although smoking represents the main pathogenetic factor, inheritance also plays a part. However, the identification of possible predisposing genetic factors is difficult, because of their low penetrance. We took advantage of murine strains that are genetically susceptible or resistant to lung tumour development, to map murine genes associated with susceptibility to lung carcinogenesis. An F2 population of urethan-treated A/J x C3H/He mice was scored with 83 genetic markers. A chromosome 6 distal region, spanning mice was scored with 83 genetic markers. A chromosome 6 distal region, spanning 35 centiMorgans, contained a major lung tumour susceptibility locus. No other chromosomal region was significantly associated with lung tumour development.

Animals↗
PubMed1993

Molecular characterization of a thyroid tumor-specific transforming sequence formed by the fusion of ret tyrosine kinase and the regulatory subunit RI alpha of cyclic AMP-dependent protein kinase A.

The ret oncogene frequently has been found activated in papillary thyroid carcinomas. A previous characterization of ret activation revealed recombination of its tyrosine kinase domain and sequences derived from an uncharacterized locus (D10S170). The mechanism leading to this recombination was identified as a paracentric inversion of the long arm of chromosome 10, inv(10)(q11.2q21), with the breakpoints occurring where ret and D10S170 were mapped. To further characterize the activation of ret in papillary thyroid carcinomas, we have now isolated and sequenced a second type of ret oncogenic rearrangement not involving the D10S170 locus. The nucleotide sequence indicated that the transforming activity was created by the fusion of the ret tyrosine kinase domain with part of the RI alpha regulatory subunit of protein kinase A (PKA). This is the first example of an oncogenic activity involving a PKA gene. PKA is the main intracellular cyclic AMP receptor, and its RI alpha subunit gene is located on chromosome 17q. RI alpha-ret transcripts encode two isoforms of the chimeric protein (p76 and p81), which display constitutive tyrosine phosphorylation as well as a tyrosine kinase enzymatic activity. Under nonreducing conditions, both isoforms are found in a dimeric configuration because of both homo- and heterodimer formation. Thus, the in vivo activation of ret in human papillary thyroid carcinomas is provided by the fusion of its tyrosine kinase domain with different genes and can be mediated by different mechanisms of gene rearrangement.

3T3 Cells↗
PubMed1993

Gene p53 mutations are restricted to poorly differentiated and undifferentiated carcinomas of the thyroid gland.

The p53 gene was analyzed in tumor specimens obtained from 52 patients with various types of carcinoma of the thyroid gland by a combined molecular and immunocytochemical approach. The histologic types included 37 well-differentiated papillary and follicular carcinomas, 8 poorly differentiated, and 7 undifferentiated carcinomas. The p53 gene was shown to be unaffected in all differentiated tumors by single-strand conformation polymorphism analysis. However, in two out of eight (25%) of poorly differentiated carcinomas and five out of seven (71%) undifferentiated carcinomas, p53 mutations were identified and subsequently characterized by DNA sequencing. One undifferentiated carcinoma displayed two areas with varying degrees of differentiation. The comparative analysis of the p53 gene, in both the more and the less differentiated area of this tumor, clearly showed that the p53 mutation was confined to the latter component of the tumor specimen. These results indicate that mutations of the p53 gene are associated with the most aggressive histologic types of thyroid tumors, such as the undifferentiated carcinoma and, to a certain extent, the poorly differentiated carcinoma, and that the alterations of this gene represent a late genetic event in human thyroid carcinogenesis.

Adult↗
PubMed1992

Deletions of 17p and p53 mutations in preneoplastic lesions of the lung.

Cytogenetic and p53 mutation analysis in two cases of severe dysplasia of the bronchial epithelium in lung cancer patients and p53 immunostaining in a third one are reported. The finding of both chromosomal deletions of 17p and p53 mutation indicates that these changes may take place early in the process of lung carcinogenesis.

Base Sequence↗
PubMed1992

bcl-2 proto-oncogene expression in normal and neoplastic human myeloid cells.

The present study provides immunobiochemical and molecular data on the differentiation-linked expression of the bcl-2 proto-oncogene in normal and neoplastic myeloid cells. Using a recently developed monoclonal antibody (MoAb) to the bcl-2 molecule, staining of normal bone marrow myeloblasts, promyelocytes, and myelocytes, but neither monocytes nor most polymorphonuclear cells, was demonstrated. By two-color flow cytometric analysis, bcl-2 was evidenced in CD33+ and CD33+/CD34+ myeloid cells as well as in the more primitive CD33-/CD34+ population. The leukemic cell lines HL-60, KG1, GM-1, and K562 were bcl-2 positive together with 11 of 14 acute myeloid leukemias (AML) and three of three chronic myeloid leukemias (CML) in blast crises; six of seven CML were negative. Among myelodysplastic cases, augmentation of the bcl-2 positive myeloblastic compartment was found in refractory anemia with excess of blasts (RAEB) and in transformation (RAEB-t). Western blots of myeloid leukemias and control lymphocytes extracts evidenced an anti-bcl-2 immunoreactive band of the expected size (26 Kd). Moreover, the HL-60 and KG1 cell lines, both positive for the bcl-2 protein, exhibited the appropriate size bcl-2 mRNA (7.5 Kb). These findings clearly indicate that the bcl-2 gene is operative in myeloid cells and that the anti-bcl-2 MoAb identifies its product and not a cross-reactive epitope. Induction of HL-60 differentiation toward the monocytic and granulocytic pathways was accompanied by a marked decrease in bcl-2 mRNA and protein levels; bivariate flow cytometric analysis showed that the fraction becoming bcl-2 negative was in the G1 phase of the cell cycle. These data establish that the bcl-2 proto-oncogene is expressed on myeloid cells and their progenitors and is regulated in a differentiation-linked manner.

Anemia, Refractory, with Excess of Blasts↗
PubMed1992

Flow cytometric detection of the mitochondrial BCL-2 protein in normal and neoplastic human lymphoid cells.

The bcl-2 proto-oncogene, rearranged and deregulated in B-cell lymphomas bearing the t(14;18) translocation, encodes an inner mitochondrial membrane protein that blocks apoptotic cell death. We have developed a sensitive immunofluorescence assay for the single- and multicolor flow cytometric analysis of bcl-2 protein in relation to other markers and cell cycle, based on a fixation-permeation step of cells with paraformaldehyde and Triton X100 and the use of a bcl-2 specific monoclonal antibody (MoAb). As an application of this method, we have examined the expression of bcl-2 in normal and neoplastic lymphoid cells. We have found that greater than 80% of normal T-and B-cells are bcl-2 positive; following in vitro mitogen activation, the bcl-2 reactivity decreased slightly in the former but markedly in latter cells. In both cases the bcl-2 expression was not restricted to a specific phase of the cell cycle, as evidenced by two-color analysis. On lymphoblastoid cell lines, the bcl-2 staining intensity was variable and not necessarily correlated to molecular rearrangements of the bcl-2 gene. Among fresh B-cell non-Hodgkin's lymphomas (B-NHL), most sporadic Burkitt's cases were bcl-2 negative. Of four centroblastic-centrocytic cases with rearrangements of the bcl-2 gene, only two presented elevated amounts of bcl-2 protein, indicating that the levels of bcl-2 are not diagnostic of the translocation.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗