Biomedical subjects

G Esposito

Publications and source records attributed to G Esposito.

At least 181 records · Page 10Linked to original sources

PubMed1994

Dopaminergic system activity and cellular defense mechanisms in the striatum and striatal synaptosomes of the rat subchronically exposed to manganese.

In 6-month-old male Wistar rats, levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), ascorbic acid (AA), dehydroascorbic acid (DHAA), uric acid and glutathione (GSH) were determined by HPLC in the striatum and striatal synaptosomes after subchronic oral exposure to MnCl2 50-100-150 mg/kg. Mn significantly decreased levels of DA and GSH and increased levels of DHAA and uric acid both in the striatum and synaptosomes. In synaptosomes, individual total Mn doses/rat were directly correlated with individual DOPAC/DA ratio values (r = +0.647), uric acid (r = +0.532) and DHAA levels (r = +0.889) and inversely correlated with DA (r = -0.757) and GSH levels (r = -0.608). In turn, GSH levels were inversely correlated with uric acid (r = -0.451) and DHAA levels (r = -0.460). In conclusion, the response of striatal cellular defense mechanisms (increase in AA oxidation, decrease in GSH levels) correlated well with changes in markers of dopaminergic system activity and increase in uric acid levels. The latter provides evidence of an Mn-induced oxidative stress mediated by xanthine oxidase.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1994

Coronary artery vasoconstriction after successful single angioplasty of the left anterior descending artery.

Percutaneous transluminal coronary angioplasty is associated with spontaneous transient vasoconstriction. The mechanisms by which coronary vasoconstriction occurs distally to a successful dilated stenosis after coronary artery angioplasty are still unknown. The present study was planned to investigate the effect of successful coronary artery angioplasty on coronary vasomotion distal to a dilated stenosis and in the control vessel and the role of alpha-adrenergic receptors on coronary vasomotion after successful coronary artery angioplasty. We prospectively studied 32 consecutive patients scheduled for elective single coronary artery angioplasty of the left anterior descending coronary artery. Only aspirin, 325 mg, or nitroglycerin was allowed in the week before the study; no premedication with diazepam or other drugs was given. In group 1 (control patients, n = 20), quantitative coronary angiography was performed in the control state; 5 and 15 minutes after coronary artery angioplasty; and after intracoronary nitroglycerin infusion, 300 micrograms. In group 2 (n = 12), intracoronary phentolamine, 2 mg, was infused regionally through the balloon catheter before the coronary artery angioplasty, and coronary angiography was performed at baseline, 15 minutes after balloon deflation, and after nitroglycerin infusion. In group 1, constriction of the coronary segment distal to a dilated stenosis (2.4 +/- 0.8 to 2.1 +/- 0.6 mm, -14.6% vs baseline; p < 0.05) and of the circumflex coronary artery segment (2.8 +/- 0.7 to 2.5 +/- 0.6 mm, -10.7% vs baseline, p < 0.05) occurred 15 minutes after coronary artery angioplasty. The degree of vasoconstriction was not correlated with the lesion severity before coronary artery angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗

PubMed1994

In vitro receptor imaging for characterization of human solid tumors.

Since many of the factors involved in tumor growth and progression act through a receptor-mediated mechanism, we applied in vitro receptor imaging techniques to study the intratumoral distribution and concentration of receptor-molecules having experimental biological relevance in such processes. Here we summarize the results of a study concerning the role of urokinase receptor (uPAR) in the acquisition of an invasive phenotype by tumor cells. Independently of the system studied, we demonstrated that in vitro receptor imaging techniques can be used to define the biological characteristics of human solid tumors and can contribute to clarify the complex network of ligand/receptor interactions leading to tumor spread.

Autoradiography↗

PubMed1994

Multiple CT imaging in pressure sores.

In patients affected by pressure sores, bones can be reached easily by the infection. This suggested a new way for a more precise diagnostic evaluation, looking at the most recent technological knowledge, which can offer a better evaluation of single lesions for a better planning of surgical operations. The possibility of performing multiple imaging under a CT guide, as well as a simple technique for contrast permanence within the sore, led the authors to demonstrate the validity of modern CT scanning as a main diagnostic method.

Bone Diseases↗

PubMed1994

Forearm vascular responsiveness to alpha 1- and alpha 2-adrenoceptor stimulation in patients with congestive heart failure.

BACKGROUND: The alpha-adrenergic component of the sympathetic nervous system plays a major role in the pathophysiology, clinical manifestations, and natural history of human congestive heart failure (CHF). However, the functional integrity of vascular alpha 1- and alpha 2-adrenoceptors in CHF remains to be elucidated. The present study was designed to assess the vascular responsiveness of alpha 1- and alpha 2-adrenoceptors in patients with CHF. METHODS AND RESULTS: To evaluate alpha 1- and alpha 2-adrenoceptor responsiveness, we studied the effects of the regional infusion into the brachial artery of increasing doses of phenylephrine (a selective alpha 1-adrenoceptor agonist) and BHT 933 (a selective alpha 2-adrenoceptor agonist) on vascular responses in 12 healthy subjects and in 24 patients with CHF secondary to primary dilated cardiomyopathy or ischemic heart disease. Left ventricular ejection fraction was measured by radionuclide angiography, and forearm blood flow was determined by venous occlusion plethysmography. Phenylephrine reduced forearm blood flow in normal subjects from 5.2 +/- 0.9 to 2.5 +/- 0.6 mL per 100 mL of tissue/min (P < .05) at the highest dose (-50.8 +/- 4.8% versus baseline). A similar vasoconstriction was obtained in patients with CHF (from 3.5 +/- 0.5 to 1.5 +/- 0.2 mL per 100 mL of tissue/min (P < .05) (-58.7 +/- 5.0% versus baseline). The dose-response curves produced by phenylephrine in the two groups were comparable. The highest dose of BHT 933 reduced forearm blood flow in normal subjects from 5.3 +/- 0.9 to 2.3 +/- 0.6 mL per 100 mL of tissue/min (P < .05) (-59.0 +/- 4.9% versus baseline). In patients with CHF, a similar vasoconstriction was obtained (from 4.2 +/- 0.8 to 1.5 +/- 0.3 mL per 100 mL of tissue/min, P < .05, -62.1 +/- 6.5% versus baseline). The dose-response curves produced by BHT 933 also were comparable in the two groups. In patients with CHF, plasma concentrations of norepinephrine were significantly higher than in normal subjects. CONCLUSIONS: The results of the present study demonstrate that alpha 1- and alpha 2-adrenoceptor stimulations produced an equivalent vasoconstriction in patients with CHF and in normal subjects. This indicates that the vascular responsiveness to alpha-adrenoceptor agonists may be preserved in the limb vessels of patients with CHF.

Adrenergic alpha-Agonists↗

PubMed1994

[Gene therapy for the treatment of restenosis after coronary angioplasty].

Accumulation and proliferation of vascular smooth muscle cells are associated with atherosclerosis and hypertension. Proliferation of smooth muscle cells constitutes a major pathological event responsible for long-term failure of coronary and peripheral arterial bypass graft as well as the development of restenosis after percutaneous transluminal coronary angioplasty (PTCA). The incidence of restenosis after PTCA has been reported to be as high as 40-45% within 3-6 months. Major advantages in recombinant deoxyribonucleic acid (DNA) technology and eukaryotic gene regulation allow to hypothesize gene therapy as a potential treatment for inherited and acquired diseases. Gene therapy is the introduction of genes into somatic cells to correct an inherited or acquired disorder through the synthesis of missing or defective protein. Although no disease has yet been treated by gene therapy, several gene transfer protocols have recently been undertaken. We have studied the expression of foreign DNA that has been introduced into smooth muscle cells after balloon carotid injury in a rat model of angioplasty. The effects of different degree of balloon injury on neointima formation and c-fos expression was also assessed. Our data demonstrate that site-specific gene expression can be achieved by direct gene transfer in vivo and could be applied to the treatment of restenosis after PTCA.

Angioplasty, Balloon, Coronary↗

PubMed1994

Soluble interleukin-2 receptor: a new marker in pancreatic adenocarcinoma?

An increase in soluble Interleukin-2 receptor has been observed in several lymphoproliferative diseases and in certain solid neoplasms. Little is known, however, of the serum levels of this marker in pancreatic cancer. We studied the behaviour of the soluble Interleukin-2 receptor in 32 patients with pancreatic cancer versus 17 patients with alcoholic chronic pancreatitis and 24 healthy controls. The results obtained showed a significant statistical difference (Student's "t"-test and Mann Whitney U test) between pancreatic cancer on one hand and chronic pancreatitis plus healthy controls on the other (p < 0.0001).

Adenocarcinoma↗

PubMed1994

Cell kinetics and polyamine enzymes in the intestinal mucosa of rats with azoxymethane induced tumours.

We studied the proliferative activity and the modifications in ornithine decarboxylase (ODC) and diamine oxidase (DAO), enzymes involved in polyamine metabolism, in the apparently normal intestinal mucosae of rats with azoxymethane induced tumours. Fifty rats were treated with six weekly injections of 15 mg/kg body weight azoxymethane (AOM). Six rats died during the treatment. All the surviving rats developed intestinal tumours; tumour incidence was 93.1% (41/44) in the left colon, 40.9% (18/44) in the right colon and 45.4% (20/44) in the small bowel. In the normal-appearing mucosa close to intestinal tumours we found an extension of the normal proliferative compartment to the upper third of the crypts (stage I abnormality) and a shift of most of the DNA synthesizing cells from the basal region to the middle and upper third (stage II abnormality). Furthermore, the intestinal mucosa characterized by proliferative abnormalities showed an ODC activity significantly higher than the normal mucosa of control rats (small bowel: 1.01 +/- 0.26 vs 0.42 +/- 0.15, P < 0.01; right colon: 1.32 +/- 0.34 vs 0.25 +/- 0.02, P < 0.001; left colon: 1.93 +/- 0.35 vs 0.22 +/- 0.01, P < 0.01). We also detected a significant decrease of DAO activity in the mucosa of the small bowel and right colon of treated rats compared to controls (0.86 +/- 0.09 vs 4.39 +/- 0.85, P < 0.01; 1.04 +/- 0.43 vs 3.80 +/- 0.91, P < 0.01, respectively), while DAO activity in the left colon was unchanged. The lower incidence of tumours in the small bowel and right colon suggests the presence of factors protecting these segments from carcinogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amine Oxidase (Copper-Containing)↗

PubMed1993

Structural study of rat thyroid transcription factor 1 homeodomain (TTF-1 HD) by nuclear magnetic resonance.

The 500 MHz 1H NMR spectrum of a 68-residue peptide, encompassing the rat thyroid transcription factor 1 homeodomain (TTF-1 HD), was fully assigned using standard 2D NMR methodology. The secondary structure elements and their spatial organization were determined and led to a structure very similar to that previously described for other homeodomains and expected also for TTF-1 HD from homology modeling predictions. The three-dimensional arrangement of the three helix fragments of TTF-1 HD preserves the helix-turn-helix motif commonly occurring in many classes of DNA-binding proteins.

Amino Acid Sequence↗

PubMed1993

Correlation between 1-methyl-4-phenylpyridinium ion (MPP+) levels, ascorbic acid oxidation and glutathione levels in the striatal synaptosomes of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated rat.

In 6-month-old male Wistar rats, levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), ascorbic acid (AA), dehydroascorbic acid (DHAA), uric acid, glutathione (GSH) and 1-methyl-4-phenylpyridinium ion (MPP+) were determined by HPLC in the crude striatal synaptosomal fraction after single injections of MPTP 35 mg/kg i.p. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced a 32.5% death rate within 15 min to 10 h. Groups of surviving rats were sacrificed 1, 3, 8 and 24 h after MPTP. MPTP significantly increased levels of DHAA and uric acid and decreased levels of DOPAC and GSH. Individual synaptosomal levels of MPP+ were correlated inversely with DOPAC (r = -0.601, P < 0.002) and GSH levels (r = -0.496, P < 0.02) and directly with levels of uric acid (r = +0.627, P < 0.001); these latter, in turn, were correlated with DHAA (r = +0.418, P < 0.05) and GSH levels (r = -0.357, P = 0.07). In conclusion, the response of the endogenous antioxidant system (increase in AA oxidation, decrease in GSH levels) correlates well with the MPTP-induced increase in uric acid levels and provides further evidence for a mechanism of MPTP neurotoxicity involving oxidative stress produced by xanthine oxidase.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1993

Conformational study of a short Pertussis toxin T cell epitope incorporated in a multiple antigen peptide template by CD and two-dimensional NMR. Analysis of the structural effects on the activity of synthetic immunogens.

The immunogenic efficacy of multiple antigen peptides, MAPs, i.e. branched molecules in which multiple copies of a given immunogenic peptide are attached on a scaffold of lysine residues via both alpha and epsilon linkages, has been repeatedly demonstrated, but little is known about the structural arrangement of these peptide constructs. A conformational characterization was therefore performed for a known T cell epitope of the S1 subunit of Pertussis toxin, whose sequence is predicted to form alpha-helix. The peptide DNVLDHLTGR, its N-acetylated and C-amidated analogue and a tetrabranched MAP based on the N-acetylated peptide were prepared and studied by CD and two-dimensional 1H-NMR. No evidence of helical structure was obtained in water for the isolated peptides. In contrast, in triflouroethanol, the isolated epitopes fold into a helical structure spanning the segment Val3-Thr8 in the uncapped molecule and encompassing also the N-terminal region in the capped analogue. The mobile C-terminal region tends to adopt a distorted turn arrangement in both peptides due to the folding of Arg10 guanidinium over the backbone. No distortion of the helix structure was observed for the single-copy epitope in the four-branched MAP molecule in trifluoroethanol: each peptide chain is equivalent within the MAP and shows an even more regular helical pattern than the isolated end-blocked sequence. A slight difference was located at the junction with the lysine scaffold: the peptide bond to epsilon NH was found in a much more extended conformation than the corresponding link to alpha NH. These structural results correlate with in vitro T cell stimulatory activity of the three compounds examined and provide arguments supporting the previous suggestion that MAP tetramers are unlikely to elicit an immune response specific for the synthetic template assembly, a feature necessary to retain the advantage of the polymeric epitope presentation.

Amino Acid Sequence↗

PubMed1993

[The surgical treatment of inflammatory aneurysms of the abdominal aorta. The usefulness of nuclear magnetic resonance (MR) in the preoperative diagnosis].

Inflammatory abdominal aortic aneurysms (IAAA) represent a peculiar variant compared with the common atherosclerotic origin of aortic aneurysms. Between January 1988 and March 1992, 111 aneurysmectomies were performed at our institution: 98 elective and 13 emergency procedures. In 10 cases (all males, mean age 68.5) an IAAA was found. 8/10 of those patients operated upon electively were studied preoperatively with MRI. All the IAAA but one were correctly identified preoperatively. Identification of IAAA with MRI in these cases improved the surgical approach. In conclusion, patients with IAAA can be operated upon safely especially if a preoperative diagnosis is present. MRI greatly improves our ability to characterize non invasively IAAA.

Aged↗

PubMed1993

Effects of ageing on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxic effects on striatum and brainstem in the rat.

In 3- and 18-month-old male Wistar rats, levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), ascorbic acid (AA), dehydroascorbic acid (DHAA), noradrenaline (NA), uric acid, glutathione (GSH) and 1-methyl-4-phenylpyridinium ion (MPP+) were determined by HPLC in the striatum and/or in the brainstem 24 h after single injections of MPTP (12-35 mg/kg i.p.). Aged rats had lower baseline levels of AA and GSH, compared to young rats. In aged rats, MPTP 35 mg/kg induced a 70% death rate and a decrease in striatal DOPAC/DA ratio which was significantly correlated to MPP+ concentrations (r = -0.840, P < 0.005); in addition, MPTP did not increase AA oxidation. In the brainstem, the MPTP-induced decrease in NA levels and increase in uric acid levels were significantly correlated to the MPP+ concentrations (r = -0.709, P < 0.05, and r = +0.888, P < 0.001, respectively). In conclusion, evidence is given of a mechanism of toxicity of MPTP involving oxidative stress produced by xanthine oxidase; in addition, in aged rats the neuronal antioxidant system (levels of AA and GSH) is considerably lower than in young rats and may play an enabling role in the MPTP age-related neurotoxic effects on striatum and brainstem.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1993

Receptor phage. Display of functional domains of the human high affinity IgE receptor on the M13 phage surface.

In this paper we demonstrate that phage display technology is a suitable system for studying the interaction between the high-affinity receptor for IgE (Fc epsilon RI) and IgE. The alpha subunit extracellular domains of the human receptor were expressed on the surface of filamentous phage M13 fused to the carboxyl-terminal part of the gene III protein (pIII). Two constructs were made, the first with both the Ig-like domains of the receptor alpha chain and the second with only the C-terminal domain. The fusion genes were cloned in a phagemid vector to display monovalently the receptor on the phage surface. Our results indicate that the alpha receptor expressed on the phage is able to interact with IgE as demonstrated by an ELISA assay. In addition, by using the same system, we show that a single domain of the alpha receptor is sufficient for the interaction with IgE although with a binding affinity lower than that of the two-domain receptor.

Bacteriophage M13↗

PubMed1993

Human urokinase receptor concentration in malignant and benign breast tumors by in vitro quantitative autoradiography: comparison with urokinase levels.

We measured the tissue concentration of human urokinase receptor (uPAR) in 22 breast carcinomas and 9 benign breast lesions using in vitro quantitative autoradiography. Tissue sections were incubated with increasing concentrations of 125I-pro-urokinase in the presence or absence of unlabeled competitor. Breast carcinomas were found to contain 5 times more uPAR than benign breast lesions with respect to their protein content [523 +/- 72 versus 108 +/- 20 (SE) fmol/mg (P < 0.001)]. Simultaneous quantitation of urokinase (uPA) by immunoenzymatic assay on tissue extracts from the same specimens showed that breast carcinomas also contain 19 times more uPA than benign tumors (611 +/- 134 versus 32 +/- 8 fmol/mg) (P < 0.01). The reliability of quantitative autoradiography measurements was confirmed by uPAR cross-linking assay on membrane fraction from either U937 histiocytic lymphoma cells or breast carcinomas and immunoperoxidase staining with an anti-uPAR antibody on tumor sections. Also, immunoperoxidase staining with an anti-uPA monoclonal antibody showed that uPA is indeed localized on the plasma membrane of epithelial tumor cells in confined areas of breast carcinomas whereas cells from benign breast lesions were devoid of uPA under the same experimental conditions. In conclusion, our findings support the hypothesis that uPAR plays a central role in the acquisition of an invasive phenotye and favor its potential use as a prognostic factor in patients with breast carcinoma.

Adult↗

PubMed1993

Probing protein structure by solvent perturbation of NMR spectra. II. Determination of surface and buried residues in homologous proteins.

The experimental assignment of most residues in a protein to the surface or interior is in principle possible without prior solution of a complete three-dimensional structure. The method described is based on nmr measurements that determine the amino acid composition of the surface of a protein [A. Petros, L. Mueller, and K.D. Kopple (1990) Biochemistry, Vol. 29, pp. 10041-10048; G. Esposito, A. M. Lesk, H. Molinari, A. Motta, N. Niccolai, and A. Pastore (1992) Journal of Molecular Biology, Vol. 224, pp. 659-670]. If these measurements are carried out on several homologous proteins of known sequence, it is possible to combine the results to determine, in most cases, which positions in the sequence contain exposed residues.

Amino Acid Sequence↗

PubMed1993

Cytosine arabinoside increases the binding of 125I-labelled epidermal growth factor and 125I-transferrin and enhances the in vitro targeting of human tumour cells with anti-(growth factor receptor) mAb.

We report that cytosine arabinoside (Ara-C), a cytosine analogue that at low doses causes phenotypical changes on human leukemia cells in vitro and in vivo, induces growth inhibition of oropharyngeal cancer KB and lung adenocarcinoma A549 cell lines. An increase in the number of epidermal growth factor and transferrin receptors (EGFR, TrfR) is induced by Ara-C on these cells. Maximal EGFR up-regulation occurs 96 h after the beginning of Ara-C exposure while maximal TrfR up-regulation is detected 24 h later. These effects occur without changes in the affinity of EGFR and TrfR for their ligands. Two classes of EGF-binding sites with a Kd of 0.055 nM and 2.3 nM respectively, and one class of transferrin-binding sites with a Kd of about 4 nM are detected on both untreated and Ara-C-treated KB cells. [3H]Thymidine uptake is clearly stimulated on KB cells by nanomolar concentrations of EGF and transferrin, whereas in Ara-C-treated cells [3H]thymidine uptake is not increased by EGF and transferrin under conditions where maximal EGFR and TrfR up-regulation occurs. The enhanced EGF and transferrin binding is paralleled by a twofold increase of in vitro targeting of Ara-C-treated KB and A549 cells with anti-EGFR 108.1 mAb and anti-TrfR OKT9 mAb. We propose that Ara-C could provide a new approach for the improvement of the therapeutic index of anti-EGFR and anti-TrfR immunoconjugates.

Adenocarcinoma↗

PubMed1993

Intermediate and high grade malignant non-Hodgkin's lymphomas: preliminary results using a new combination regimen (EVE-COPEM).

Between 1988 and 1992, 60 patients with intermediate and high-grade non-Hodgkin's lymphomas (NHL) were treated with a new multidrug combination chemotherapy including 4'epidoxorubicin (25 mg/m2), etoposide (60 mg/m2), cyclophosphamide (400 mg/m2), administered intravenously (i.v.) on the 1st, 2nd and 3rd day every 4 weeks, prednisone (40 mg/m2) orally for 6 days every 4 weeks, vincristine (1 mg/m2) i.v. and methotrexate (400 mg/m2) i.v. on the 8th day every 4 weeks, vindesine (2.5 mg/m2) and cytarabine (200 mg/m2) on the 15th day every 4 weeks. Patients achieving apparent complete remission (CR) or good partial response (PR) after the 1st cycle of therapy were submitted to three other cycles of the same therapy. Patients failing to respond to the 1st cycle or whose disease progressed despite therapy, were treated with an alternative 2nd line therapy. Seventeen patients (28%) had stage II-II E, 15 (25%) stage III and 28 (47%) stage IV disease. Tumoral mass > 10 cm was found in 28 cases, the presence of extranodal sites (ES) in 32 cases, serum lactate dehydrogenase (LDH) > 240 IU/l in 34 cases, performance status (PS) > or = 2 in 12 cases. CR was obtained in 46 (76.4%) out of the 60 patients. Relapse-free survival (RFS) was 82, 64 and 61% with a median follow-up of 12, 24 and 36 months respectively. No relapse occurred later than 26 months after achievement with CR thus far. Overall survival (OS) was 77% at 12 months and calculated to be 62% and 59% at 24 and 36 months, respectively. Two patients died as a result of the treatment. Reversible myelosuppression was the main toxic effect. One hundred and ten out of the 221 cycles of chemotherapy were delayed because of therapy toxicity. Negative prognostic factors on the RFS and OS were the presence of an advanced stage of disease, a mass larger than 10 cm, the presence of ES, the elevated LDH, the PS > or = 2, the delay of therapy. In conclusion, results obtained using our protocol overlap those from other third generation regimens. Toxicity was also similar. The influence of clinical conditions such as stage of disease, the presence of ES, high LDH level and tumoral mass > 10 cm on the RFS and OS were significant. Principal variables influencing prognosis must be unified to compare results of similar treatments from different institutions.

Adult↗