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Biomedical subjects

C Porta

Publications and source records attributed to C Porta.

At least 91 records · Page 5Linked to original sources
PubMed1996

The development of cowpea mosaic virus as a potential source of novel vaccines.

Epitopes from human rhinovirus 14 (HRV-14) and human immunodeficiency virus type (HIV-1) have been expressed on the surface of particles of the plant virus, cowpea mosaic virus (CPMV). The chimaeras retain their ability to grow in plants and large quantities of virions can be easily purified. Immunological studies have shown that purified particles have the antigenic properties of the insert, and, in the case of the HIV-1 chimaera, can elicit the production of neutralising antibodies in mice. The chimaera containing the epitope from HRV-14 has been crystallised and the crystals shown to diffract to atomic resolution.

AIDS Vaccines↗
PubMed1996

Granulocyte dysplasia and dysfunction, and CD11/CD18 defects in myelodysplastic syndromes.

In myelodysplastic syndromes (MDS), dysplastic changes in neutrophils are a common feature reflecting the total degree of bone marrow dysplasia. Furthermore, granulocyte function is abnormal, so that a high risk of life-threatening infections has been documented. In this review we shall focus on the defects of both granulocytes and their CD11b/CD18 glycoprotein complex, which regulate granulocyte adherence, locomotion, diapedesis and migration into inflammatory sites, in patients suffering from primary MDS. The defective surface membrane glycoprotein expression of myelodysplastic phagocytes is not only a useful diagnostic tool, but also a powerful prognostic one, since MDS patients with such defects present both an increased susceptibility to infections and a decreased survival. Moreover, the administration of colony-stimulating factors is known to be able to elicit long-lasting improvement in neutrophil count, CD11b/CD18 expression and function, marrow myeloid maturation, and possibly to decrease bacterial infections in MDS patients.

CD11 Antigens↗
PubMed1996

Verapamil inhibits to different extents agonist-induced Ca2+ transients in human tumor cells and in vitro tumor cell growth.

Platelet agonists are known to contribute to the regulation of cytoplasmic Ca2+ levels in tumor cells and this property could be relevant in the stimulation of cell proliferation. In the present study we investigated the ability of ADP, collagen and thrombin to increase cytoplasmic Ca2+ levels in different human tumor cell lines (mesothelioma, DND-1A melanoma, HeLa uterine carcinoma) and we analyzed the effect of the calcium channel blocker verapamil on Ca2+ fluxes and on in vitro tumor cell growth. ADP was able to induce a transient increase in the cytoplasmic Ca2+ concentration in tumor cells from all lines; collagen showed this effect in mesothelioma cells and in HeLa cells, and thrombin was effective only in mesothelioma cells. Verapamil inhibited Ca2+ fluxes induced by the effective agonists in a dose-dependent manner. Values of IC50 for inhibition of ADP-induced Ca2+ transients were 63.5 microM in mesothelioma cells, 97.3 microM in DND-1A cells and 93.5 microM in HeLa cells, while those for inhibition of collagen-induced Ca2+ movements were slightly higher (170.2 microM in mesothelioma cells and 112.3 microM in HeLa cells) and the value of IC50 for inhibition of thrombin-induced Ca2+ fluxes (evaluated only in mesothelioma cells) was lower (22.5 microM). The drug dose-dependently also inhibited the in vitro growth of tumor cells; values of IC50 for growth inhibition were 21.8 microM in mesothelioma cells, 9.1 microM in DND-1A cells and 6.4 microM in HeLa cells, suggesting that the antiproliferative activity of verapamil was partly Ca(2+)-independent. These data may be of interest to elucidate the mechanisms of the two-way interactions of tumors with the hemostatic system and may help to identify new pharmacologic strategies for their control.

Adenosine Diphosphate↗
PubMed1995

HLA-A, B, C, DR and DQ expression and hepatocellular carcinoma: study of 205 Italian subjects.

We have evaluated the frequency of HLA class I and II antigens in 205 Italian patients with hepatocellular carcinoma (HCC) and 749 blood donors (controls). Moreover, we have looked for correlations between HLA antigen frequencies and HBV and/or HCV infections in HCC patients. We found great differences in HLA antigen frequencies considering only two groups: HCC patients and controls. The polymorphism is smaller when we consider the different groups of HCC patients in regard to the previous viral infections (HBV and/or HCV). The most interesting finding is the higher frequency of Cw7, B8 and DR3 in almost all groups of HCC patients. It is well known, that the HLA A1, Cw7, B8, DR3 antigen haplotype is associated with a rapid decline of CD4 cells, and HLA B8, DR3 positive subjects may display some changes in immune parameters and are prone to develop several immunological diseases. Thus HCC might be the result of a lower sensitivity (genetically given) to mitogenic stimuli of HBV and HCV.

Aged↗
PubMed1995

Effect of different platelet agonists on intracellular free Ca++ concentrations in human tumor cells: possible role in tumor growth.

Modulation of cytoplasmic Ca++ concentration is a mechanism common to signal transduction pathways regulating many cellular phenomena, including the interactions of tumors with the hemostatic system. We have investigated the pro-aggregating and pro-coagulant activities of human tumor cell lines cultured in vitro and the ability of different platelet agonists to induce Ca++ transients in these cells. Cells of a malignant mesothelioma line activated platelets by a thrombin-dependent mechanism; on the contrary, HeLa cells, derived from a uterine cervical cancer, possessed ADP-dependent pro-aggregating activity, and DND-IA melanoma cells did not stimulate platelet aggregation. All cell lines showed a tissue-factor-like procoagulant property, more pronounced in mesothelioma cells. Furthermore, ADP was able to induce a transient increase in cytoplasmic Ca++ concentration in tumor cells from all lines; collagen showed this effect in mesothelioma cells and in HeLa cells, and thrombin was effective only in mesothelioma cells. PAF never induced Ca++ fluxes in any of the cell lines investigated. Finally, the calcium-channel blocker verapamil inhibited agonist-induced Ca++ transients in tumor cells and in vitro tumor-cell growth. These data may help to identify new possible mechanisms of the 2-way interaction of tumors with the hemostatic system.

Adenosine Diphosphate↗
PubMed1995

Hydrochlorothiazide action on the apical Cl-, Ca2+ and K+ conductances in rabbit gallbladder epithelium. Presence of an apamin-sensitive, Ca(2+)-activated K+ conductance.

In the rabbit gallbladder epithelium, hydrochlorothiazide (HCTZ) was shown to inhibit the transepithelial NaCl transport and the apical Na(+)-Cl- symport, to depolarize the apical membrane potential and to enhance the cell-to-lumen Cl- backflux (radiochemically measured), this increase being SITS-sensitive. To better investigate the causes of the depolarization and the Cl- backflux increase, cells were punctured with conventional microelectrodes on the luminal side (incubation in bicarbonate-free saline at 27 degrees C) and the apical membrane potential (Vm) was studied either with prolonged single impalements or with a set of short multiple impalements. The maximal depolarization was of 3-4 mV and was reached with 2.5 x 10(-4) M HCTZ. It was significantly enhanced by reducing luminal Cl- concentration to 30 mM; it was abolished by SCN-, furosemide, SITS; it was insensitive to DPC. SITS converted the depolarization into a hyperpolarization of about 4 mV; this latter was apamin, nifedipine and verapamil sensitive. It was concluded that HCTZ concomitantly opens apical Cl- and (probably) Ca2+ conductances and, indirectly, a Ca(2+)-sensitive, apamin inhibitable K+ conductance: since the intracellular Cl- activity is maintained above the value predicted at the electrochemical equilibrium, the opening of the apical Cl- conductance depolarizes Vm and enhances Cl- backflux. In the presence of apamin or verapamil, to avoid the hyperpolarizing effects due to HCTZ, the depolarization elicited by this drug was fully developed (7-10 mV) and proved to be Ca2+ insensitive. On this basis and measuring the transepithelial resistance and the apical/basolateral resistance ratio, the Cl- conductance opened by HCTZ has been estimated and the Cl- backflux increase calculate: it proved to be in the order of that observed radiochemically. The importance of this Cl- leak to the lumen in the overall inhibition of the transepithelial NaCl transport by HCTZ has been evaluated.

Animals↗
PubMed1995

Human immunodeficiency virus type 1-neutralizing antibodies raised to a glycoprotein 41 peptide expressed on the surface of a plant virus.

An oligonucleotide encoding the amino acids 731-752 of the gp41 envelope protein of the human immunodeficiency virus type 1 strain IIIB, which is known to induce cross-reactive neutralizing antibodies in humans, was inserted into a full-length clone of the RNA encoding the coat proteins of cowpea mosaic virus (RNA 2 of CPMV). When transfected together with RNA 1 of CPMV, transcribed RNA 2 was able to replicate in plants and form infectious virions (CPMV-HIV). Purified virions were injected subcutaneously with alum adjuvant into adult C57/BL6 mice to determine their ability to stimulate ELISA and neutralizing antibody specific for HIV-1. Antisera to CPMV-HIV obtained after only two injections gave a strong ELISA response (mean of 1:25,800) using the free gp41 peptide as antigen, showing that the gp41 peptide incorporated into the chimera was immunogenic. The same antisera gave 97% neutralization of HIV-1 IIIB at 1:100 dilution, with a highly uniform response in all (six of six) animals tested. A third injection barely increased the neutralization titer. Normal mouse serum had no neutralizing activity. Antisera also strongly neutralized the HIV-1 strains RF and SF2. ELISA and neutralizing activity to HIV-1 IIIB declined after the second injection and were undetectable after 7 weeks, but were restimulated to the same level after the third injection. Neutralization was marginally more stable after the third injection. Antibody specific for CPMV epitopes was equally short lived. A bonus of this system was unexpected neutralizing activity specifically stimulated by unmodified CPMV virions, although this amounted to no more than 10% of the neutralizing activity stimulated by the CPMV-HIV chimera.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Selective transport of microparticles across Peyer's patch follicle-associated M cells from mice and rats.

M cells are specialized structures in the Peyer's patch follicle-associated epithelium capable of taking up bacteria, viruses and other pathogens for later presentation to the gut-associated lymphoid tissue. The present work studies how coating microspheres with different proteins affects their ability to be taken up by M cells under near physiological conditions in vivo. The later appearance of microspheres in intestinal lymph has also been measured by flow cytometry. The protein preparations used in these experiments included bovine serum albumin (bSA), human immunoglobulin G (hIgG), secretory immunoglobulin A (hIgA), bovine growth hormone (bGH) and bGH complexed with an IgG antibody raised against bGH (bGH-Ab). Selectivity in binding of these microspheres to M cells, determined by confocal microscopy, was bGH < bSA < hIgG (mice) and bGH < bGH-Ab (rats and mice). A similar selectivity was seen for microsphere entry into M cells (bGH < bSA < hIgG; bGH < bGH-Ab). The appearance of protein-coated microspheres in rat mesenteric lymph showed a similar selectivity to that found for binding and entry into M cells (bGH < bGH-Ab). This latter selectivity was also found for hIgA-coated microspheres (bSA < hIgA). Preservation of transport selectivity throughout transcytosis highlights the unique importance of the M cell surface as being the primary site determining which type of antigen can be presented subsequently to the gut immune system. The possibility that this is a transient or phasic property of the M cell surface and that this could have physiological relevance is also discussed.

Animals↗
PubMed1995

[Limb salvage in critical ischemia. Our experience].

The aim of this paper is to present our six-year experience in the treatment of critical limb ischaemia, even if in the period (1987-1993) considered the definition of critical ischaemia had been partly reviewed in the publication of the "European Consensus Document on Critical Limb Ischaemia" (March 1989). Two hundred thirty-nine patients have been treated in our Unit for critical limb ischaemia: reconstructive surgery was used in 34% of cases, lumbar sympathectomy or spinal cord stimulation in 17% of cases and pharmacotherapy in 14% of cases. Taking into account arterial and graft patency as well as the percentage of limb salvage, our results were similar to those presented in the literature.

Adult↗
PubMed1995

Sarcoidosis following beta-interferon therapy for multiple myeloma.

Some reports correlate the administration of all forms of interferon with the development or exacerbation of autoimmune phenomena and diseases, including sarcoidosis, because of the strong and complex immune action of interferons. We report on a case of sarcoidosis following beta-interferon treatment for multiple myeloma. Differently from what had been observed in all the 8 previously reported cases of associated multiple myeloma and sarcoidosis, where the plasmacellular malignancy followed the onset of the respiratory disease, in the case of our patient, sarcoidosis arose after multiple myeloma was first diagnosed.

Female↗
PubMed1994

Direct imaging of interactions between an icosahedral virus and conjugate F(ab) fragments by cryoelectron microscopy and X-ray crystallography.

The binding properties of seven mouse monoclonal antibodies (McAbs) raised against cowpea mosaic virus (CPMV) were characterized by conventional and inhibition enzyme-linked immunosorbent assay (ELISA) technique. McAb binding to CPMV on electron microscope (EM) grids was also assayed with gold-labeled anti-mouse antibodies. Two of the seven McAbs (5B2 and 10B7) were found to bind tighter to CPMV than the others in the inhibition ELISA and the EM assay. F(ab) fragments from both of these McAbs were prepared and complexed with CPMV in solution. Electron micrographs of flash frozen (vitrified) samples of native CPMV and CPMV complexed with F(ab) fragments from McAbs 5B2 and 10B7 as well as IgGs from 5B2 were recorded and reconstructions were computed at 23 A resolution for the CPMV/F(ab) complexes and 30 A resolution for the CPMV/IgG complex. Structures of all three complexes clearly displayed the F(ab) fragments distributed with icosahedral symmetry on the surface of CPMV. The IgG bound in a monodentate fashion with only one F(ab) attached to the virus surface. F(ab) fragments from 5B2 and 10B7 bound to nearly identical positions. The refined 2.8 A X-ray structure of CPMV was used to identify the roughly 30 amino acids covered by the F(ab) fragments. The "footprint" spans a subunit interface and appears spatially similar to antigenic site 3B on poliovirus. In a previous, preliminary report of the CPMV/F(ab) 5B2 complex (Wang et al., 1992, Nature 355, 275-278) the wrong enantiomorph of the reconstruction was chosen. This was corrected and, since the F(ab) binds close to a mirror plane, the change in the footprint was minor.

Animals↗
PubMed1994

Development of cowpea mosaic virus as a high-yielding system for the presentation of foreign peptides.

It has recently been shown that cowpea plants can be infected with a cowpea mosaic virus (CPMV) chimera containing an antigenic site from foot-and-mouth disease virus (Usha et al., Virology 197, 366-374, 1993). Analysis of progeny RNA produced during such an infection has revealed that the inserted sequence is rapidly lost during serial passaging, probably by a process of homologous recombination. Using the information gained from this analysis, we have redesigned the chimeras in such a way that they are now genetically stable. The modified constructs have been used to obtain large quantities of purified virus particles expressing epitopes derived from human rhinovirus 14 (HRV-14) and human immunodeficiency virus type 1 (HIV-1). The chimeric virus particles possess the antigenic properties of the inserted sequence and, in the case of the HRV-14-derived construct, it has been shown that the inserted epitope is immunogenic in rabbits. These results demonstrate that CPMV can be used as a high-yielding system for the presentation of foreign peptide sequences.

Amino Acid Sequence↗