Biomedical subjects

G Galati

Publications and source records attributed to G Galati.

At least 55 records · Page 3Linked to original sources

PubMed1999

Immunogenicity of apoptotic cells in vivo: role of antigen load, antigen-presenting cells, and cytokines.

Apoptosis allows the clearance of unwanted cells from living tissues without causing inflammation. Processing of phagocytosed apoptotic cells yields Ags that access the cytosol and the MHC class I pathway of engulfing cells and are recognized by Ag-specific CTL. We show here that injection of apoptotic RMA cells, a syngeneic T cell lymphoma, into C57BL/6 mice results in priming of a functional and long-lasting tumor-specific immune response. Cross-priming of CTLs by apoptotic cells requires CD4+ T cell help. Apoptotic cells, however, are at least 20-fold less immunogenic than nonreplicating live cells. Immunogenicity of apoptotic cells is proportional to the number of cells injected, correlates with the serum concentration of IL-10 and IL-1beta cytokines, and is enhanced in IL-10 knockout mice. Moreover, immunization with dendritic cells (DCs), but not macrophages (Mphi), pulsed with apoptotic cells primes tumor-specific CTLs and confers protection against a tumor challenge. Our findings demonstrate that tumor cells undergoing apoptosis are, though scarcely, immunogenic in vivo, outline the different roles of Mphi and DCs in the physiologic clearance of unwanted cells, and have implications in designing immunomodulating vaccines.

Adoptive Transfer↗

PubMed1999

A fronto-parietal system for computing the egocentric spatial frame of reference in humans.

Spatial orientation is based on coordinates referring to the subject's body. A fundamental principle is the mid-sagittal plane, which divides the body and space into the left and right sides. Its neural bases were investigated by functional magnetic resonance imaging (fMRI). Seven normal subjects pressed a button when a vertical bar, moving horizontally, crossed the subjective mid-sagittal plane. In the control condition, the subjects' task was to press a button when the direction of the bar movement changed, at the end of each leftward or rightward movement. The task involving the computation of the mid-sagittal plane yielded increased signal in posterior parietal and lateral frontal premotor regions, with a more extensive activation in the right cerebral hemisphere. This direct evidence in normal human subjects that a bilateral, mainly right hemisphere-based, cortical network is active during the computation of the egocentric reference is consistent with neuropsychological studies in patients with unilateral cerebral lesions. Damage to the right hemisphere, more frequently to the posterior-inferior parietal region, may bring about a neglect syndrome of the contralesional, left side of space, including a major rightward displacement of the subjective mid-sagittal plane. The existence of a posterior parietal-lateral premotor frontal network concerned with egocentric spatial reference frames is also in line with neurophysiological studies in the monkey.

Adult↗

PubMed1999

Cortical control of optokinetic nystagmus in humans: a positron emission tomography study.

Positron emission tomography (PET) was used to address the issue of physiological changes in the cerebral cortex associated to optokinetic nystagmus (OKN) in humans. We studied regional cerebral blood flow in eight volunteers during reflexive induction of OKN by a pattern of dots moving unidirectionally (toward the left side). We used two control conditions, with subjects passively viewing either stationary or incoherently moving dots. This paradigm was designed in order to differentiate the OKN-related activations from blood flow changes related to visual motion. When compared with the stationary condition, OKN activated a set of occipital areas known to be sensitive to visual motion. Bilateral activation was found in the striate cortex (V1) and the parieto-occipital fissure, while area V5, the intraparietal sulcus, and the pulvinar were activated only in the left hemisphere. When compared with incoherent motion, OKN activated the V1 and the parieto-occipital fissure bilaterally and the right lingual gyrus, while a signal decrease was observed in the V5 region in both hemispheres. No significant signal changes were found in areas implicated in saccades or in processing vestibular information. These results indicate that processing of OKN-related information is associated with neural activity in a specific set of visual motion areas and suggest that this network can be asymmetrically activated by a strictly unidirectional stimulation. Results are also discussed in terms of the specific kinds of OKN-related information processing subserved by each area in this network.

Adult↗

PubMed1999

The endpoints' task: an analysis of length reproduction in unilateral neglect.

When patients with left hemineglect are shown the centre of a memorised line and are asked to mark both the endpoints, they place the left one significantly farther. This contralesional bias appears to be incoherent with respect to most current interpretations of neglect [7]. In the present study, ten patients with left hemineglect and two control groups were presented the centre of a line and one of its endpoints and had to mark the missing one at the correct distance. With this modification, subjects had not to rely on stored information about the line, but simply to reproduce a distance either to the left or to the right separately. The task was performed in three different spatial locations with respect to subjects' body midline. Similarly to the original endpoints' task, neglect patients showed a leftward bias, placing the left endpoint significantly farther than the right one. However, this was not associated with a paradoxical contralesional over-extension with respect to the distance to reproduce. Indeed, when marking the left endpoint, patients were accurate (when performing in the right hemispace) or even underestimated the distance to reproduce (when performing centrally and in the left hemispace). Instead, the leftward bias was due to severe underestimation errors when marking the right endpoint, which were independent of the stimulus location. These results demonstrate that the leftward bias in the endpoints' task is relative rather than absolute and does not reflect a paradoxical overestimation in length reproduction towards the left side.

Adult↗

PubMed1999

Glutathione-dependent generation of reactive oxygen species by the peroxidase-catalyzed redox cycling of flavonoids.

Catalytic concentrations of apigenin (a flavone containing a phenol B ring) and naringin or naringenin (flavanones containing a phenol B ring) caused extensive GSH oxidation at a physiological pH in the presence of peroxidase. Only catalytic H2O2 concentrations were required, indicating a redox cycling mechanism that generated H2O2 was involved. Extensive oxygen uptake ensued, the extent of which was proportional to the extent of GSH oxidation to GSSG and was markedly increased by superoxide dismutase. These results suggest that prooxidant phenoxyl radicals formed by these flavonoids co-oxidized GSH to form thiyl radicals which activated oxygen. GSH also prevented the peroxidase-catalyzed oxidative destruction of these flavonoids which suggests that phenoxyl radicals initiated the oxidative destruction. This is the first time that a group of flavonoids have been identified as prooxidants independent of autoxidation reactions catalyzed by the transition metal ions Fe3+, Fe2+, Mn2+, and Cu2+.

Catalysis↗

PubMed1999

[The usefulness and limits of echo-endoscopy in the clinical staging of esophageal cancer].

Endoscopic ultrasonography (EUS) is a diagnostic method of considerable value for the local staging of esophageal cancer, in particular for T and N evaluation. After an extensive review of the literature, the authors underline the possibility of using EUS to improve the treatment and prognosis of esophageal neoplasms based on the use of various stage-dependent therapeutic strategies. EUS is regarded as a gold-standard technique for esophageal cancer staging in order to select appropriate treatment options, but is currently hampered by the intrinsic difficulty and subjectivity of interpreting ultrasonographic images. In order to ensure safe and reliable data, EUS must be carried out by operators who have undergone suitable training at a specialised centre.

Carcinoma↗

PubMed1999

[Prognostic criteria in ruptured aneurysm of the abdominal aorta].

A logistic regression analysis of risk factors affecting the mortality on 69 cases of ruptured abdominal aortic aneurysm (RAAA), treated between 1988-1996, has been carried out. Mortality was 33.3%. No single risk factor significantly influenced mortality except the shock (p = 0.0016). The presence of two o less risk factors in the same patient was associated with 24% mortality, whereas three o more risk factors were associated with 92.4% mortality.

Aged↗

PubMed1999

Small bowel schwannoma with diffuse subcutaneous lipomatosis. Case report and literature review.

A case of a small-bowel schwannoma with diffuse familiar lipomatosis is described. This case underlines the rarity of the neoplasm and its probably chance association with subcutaneous lipomatosis. The intestinal neoplasm was diagnosed preoperatively by upper gastrointestinal endoscopy and a small-bowel enema; computed tomography scan confirmed the intestinal lesion. Attention is focused on the morphological features of intestinal schwannomas and their biological behaviour.

Humans↗

PubMed1999

Papillary renal cell carcinoma presenting as nodal metastases to the neck.

Renal cell carcinoma, in a high percentage of patients, metastasizes early, sometimes mimicking other lesions. We present a case of an asymptomatic papillary renal cell carcinoma that presented neck metastases as the initial manifestation. The laterocervical and supraclavicular masses were considered consistent with nodal metastases from a thyroid nodule. A hemithyroidectomy was performed before the renal tumor was diagnosed. Then the patient underwent a left-side radical nefrectomy. We discuss the unpredictability of the clinical course of renal cell carcinoma.

Aged↗

PubMed1998

Mycobacterium tuberculosis exploits the CD95/CD95 ligand system of gammadelta T cells to cause apoptosis.

Vgamma9/Vdelta2+ T cells specifically recognize Mycobacterium tuberculosis in vitro and are precociously recruited in early mycobacterial lesions. Even if gammadelta T cells are only fortuitously detected in granulomas or bronchoalveolar lavages of patients with active pulmonary tuberculosis, a role in shaping the mature alphabeta T cell response against M. tuberculosis is substantiated. Here we provide a molecular explanation for this paradox: the engagement of the gammadelta TCR by mycobacterial antigens induced the expression of CD95 ligand (CD95L) by chronically activated CD95+/CD95L- gammadelta T lymphocytes. The receptor was functional, as CD95/CD95L interaction triggered the bystander death of CD95+ cells by apoptosis. Cell death was abolished by CD95-blocking antibodies. The transient accumulation at the site of infection of CD95L+ gammadelta lymphocytes, capable of interacting with CD95+ leukocytes attracted by the response towards the pathogen, may determine the characteristics of the ensuing granulomatous disease.

Apoptosis↗

PubMed1998

Tumor-driven matrix invasion by infiltrating lymphocytes: involvement of the alpha1 integrin I-domain.

Here we show that tumor cells (TC) from renal cancers regulate the migratory properties of autologous tumor-infiltrating lymphocytes (TIL), enhancing their ability to invade the extracellular matrix. A similar effect is exerted by human recombinant macrophage chemotactic protein 1 (MCP-1) and IL-8, chemokines known to increase T lymphocyte migration both across vascular endothelium and subendothelial matrix. We found that TC freshly derived from renal cell carcinoma surgical specimens constitutively secrete both IL-8 and MCP-1 and that TIL express both specific receptors. TIL matrix invasion elicited by TC is inhibited by the addition of neutralizing antisera specific for IL-8 and MCP-1, demonstrating the direct relationship between chemokine release by TC and TIL invasion. Of note, TIL invasion of the extracellular matrix requires the alpha1 integrin, which acts through its I-domain that is upregulated upon culture with MCP-1 and IL-8. Collectively, these findings suggest that TC may actively recruit TIL via the release of chemotactic factors that enhance an alpha1 integrin-mediated pathway of matrix invasion.

Antigens, CD↗

PubMed1998

Apoptotic cell clearance in systemic lupus erythematosus. I. Opsonization by antiphospholipid antibodies.

OBJECTIVE: To verify whether antiphospholipid antibodies (aPL) recognize and opsonize apoptotic human cells. METHODS: Apoptosis was induced via CD95 crosslinking or ultraviolet irradiation. IgG and anti-beta2-glycoprotein I (anti-beta2-GPI) antibodies were purified from patient sera by affinity chromatography. The aPL that bound to apoptotic cells were assessed by flow cytometry, and the subdomains recognized were identified by confocal microscopy. Human macrophages were derived from monocytes, and their ability to phagocytose 3H-labeled apoptotic bodies, whether opsonized or not opsonized by aPL, was assessed. Tumor necrosis factor alpha (TNF alpha) secretion was evaluated by enzyme-linked immunosorbent assay. RESULTS: The aPL, but not control Ig or Ig from aPL-negative patients, bound to apoptotic cells, but not to viable cells. Nuclear antigens were not recognized. Opsonization of apoptotic cells by aPL substantially enhanced recognition and binding by scavenger macrophages, with massive TNF alpha secretion. CONCLUSION: Antiphospholipid antibodies facilitate apoptotic cell clearance by macrophages and trigger TNF alpha release, possibly enhancing the immunogenicity of the autoantigens they contain.

Antibodies, Antiphospholipid↗

PubMed1998

Apoptotic cell clearance in systemic lupus erythematosus. II. Role of beta2-glycoprotein I.

OBJECTIVE: To analyze the contribution of beta2-glycoprotein I (beta2-GPI) to apoptotic cell recognition by antiphospholipid antibodies (aPL) and macrophages from patients with autoimmune disease. METHODS: Phosphatidylserine expression by Jurkat cells undergoing apoptosis upon CD95 crosslinking or ultraviolet irradiation was verified by confocal microscopy of cells stained with fluorescein isothiocyanate-labeled annexin V. Beta2-GPI was purified by heparin/cationic-exchange chromatography and was biotinylated or used to purify beta2-GPI-specific antibodies by affinity chromatography. Binding to apoptotic cells was assessed by flow cytometry. The clearance of 3H-labeled, apoptotic cells by macrophages was assessed by beta counting. RESULTS: The array of epitopes generated by beta2-GPI association with apoptotic cells specifically targets their recognition and is required for their opsonization by human aPL. Nevertheless, beta2-GPI is not required for apoptotic cell clearance by human macrophages in the absence of aPL. CONCLUSION: The proinflammatory clearance of aPL-opsonized apoptotic cells, but not the nonphlogistic clearance of apoptotic cells by scavenger macrophages, depends on beta2-GPI.

Antibodies, Antiphospholipid↗

PubMed1997

Processing of engulfed apoptotic bodies yields T cell epitopes.

Programmed death via apoptosis is the metazoan physiologic mode of cell death. Apoptotic cells are recognized by scavenger phagocytes via a number of membrane receptors and engulfed. Thereafter, little is known of their fate, or that of phagocytes. Here, we have traced apoptotic cells upon their engulfment by macrophages. After 3 h, apoptotic cells were contained in discrete well-defined vacuoles. Upon overnight chase, several small vesicles, possibly originating from the fragmentation of original vacuoles, were evident all over the macrophage body. Furthermore, Ags were diffused in the cytosol of some cells, which raises the possibility that epitopes from engulfed apoptotic cells may associate with macrophage MHC class I molecules and be recognized by T lymphocytes. Indeed, Ag-specific CTLs recognize and specifically lyse syngeneic macrophages upon phagocytosis of MHC class I-positive or -negative apoptotic cells, provided that they contain the relevant Ags. Synthesis and membrane expression of class I molecules by macrophages, together with functional transporters associated with Ag presentation, were necessary for recognition and lysis. The indirect presentation of epitopes from engulfed apoptotic cells by scavenger Ag-presenting phagocytes may, in the absence of "danger" signals, have implications for the establishment of central and peripheral self-tolerance.

Animals↗

PubMed1997

Quantitative cytometry of MHC class I digestion from living cells.

Digestion of crude membrane preparations with papain releases the extracellular portion of major histocompatibility complex (MHC) class I molecules. MHC class I molecules are integral membrane glycoprotein complexes formed by the noncovalent association of 2 invariant molecules, the heavy chain and the beta2-microglobulin (beta2-m), to a wide array of peptides. The cleaved soluble moiety retains the antigenic properties of the intact membrane-bound complex. Here we show that MHC class I digestion may be carried out on living cells, and we quantitate the surface expression of MHC complexes by a combined cytometric/high performance liquid chromatographic (HPLC) approach. Papain digestion results in time- and dose-dependent disappearance of membrane MHC-associated-fluorescence as detected by FACS analysis with MHC-specific monoclonal antibodies (mAbs). beta2-m and peptides became detectable by HPLC analysis and western blotting in the digestion buffer and were quantitated by comparison with purified standards. The cytometric assessment of the digestion allows one to simultaneously monitor efficacy and toxicity of the treatment. The procedure we describe allows to selectively retrieve by affinity chromatography MHC from the cell membrane, avoiding any contamination due to intracellular, "immature" MHC molecules.

Animals↗

PubMed1997

Neural control of fast-regular saccades and antisaccades: an investigation using positron emission tomography.

Regional cerebral blood flow changes related to the performance of two oculomotor tasks and a central fixation task were compared in ten healthy human subjects. The tasks were: (a) performance of fast-regular saccades; (b) performance of voluntary antisaccades away from a peripheral cue; (c) passive maintenance of central visual fixation in the presence of irrelevant peripheral stimulation. The saccadic task was associated with a relative increase in activity in a number of occipitotemporal areas. Compared with both the fixation and the saccadic task, the performance of antisaccades activated a set of areas including: the superior and inferior parietal lobules, the precentral and prefrontal cortex, the cingulate cortex, and the supplementary motor area. The results of the present study suggest that: (a) compared with self-determined saccadic responses the performance of fast regular, reflexive saccades produces a limited activation of the frontal eye fields; (b) in the antisaccadic task the inferior parietal lobes subserve operations of sensory-motor integration dealing with attentional disengagement from the initial peripheral cue (appearing at an invalid spatial location) and with the recomputation of the antisaccadic vector on the basis of the wrong (e.g., spatially opposite) information provided by the same cue.

Adult↗

PubMed1997

[Adenomatous tissue in colorectal carcinomas: clinical significance and probable histogenetic implications of morphological differences].

In this study we tested the hypothesis that colorectal cancers containing adenoma (CCA) could be a different entity from colon cancers without adenoma (CSA). Clinical data, histologic preparations of operative specimens and survival of 210 patients who underwent resective surgery for colorectal cancer were studied. Adenomatous tissue within the cancer was found in 62 of 210 carcinomas (CCA), the other 148 cancers were lacking adenomatous features (CSA). CCA occurred more frequently in female patients (p = 0.003). Synchronous adenomas were detected in the resected colon of 19 out 62 CCA and of 24 out 148 CSA (p = 0.04). CCA showed the extent of intraparietal spread (p = 0.001), grade (p = 0.007) and stage (p = 0.004) lower than CSA. These characteristics also appeared statistically related to size of the cancers. The adenomatous tissue within CCA was tubular in 4 cases, tubulo-villous in 34 and villous in 24 cases. The villous histotype was statistically related to the older age of patients (p < 0.0001), larger cancer size (p = 0.01), presence of synchronous adenomas in the resected colon (p = 0.02) and higher histologic grade of the cancer (p < 0.05). Patients with CCA evidenced a higher 5-year survival rate (p = 0.02). Our results evidence epidemiologic, clinical and pathologic differences between CCA and CSA and suggest a possible double histogenesis of colon cancer.

Adenoma↗

PubMed1997

[Evaluation of the respiratory function by lung scintigraphy in patients candidates for pulmonary resection].

Sixty-one patients undergoing pulmonary resection were studied pre- and post-operatively by spirometry, arterial gas determination, and quantitative ventilation/perfusion lung scanning. Our results showed that ventilation and/or perfusional scintigraphic scanning is currently the most reliable method in identifying patients at risk for postoperative respiratory insufficiency. Specifically, this technique was successful in detecting pulmonary areas other than those to be resected presenting ventilation or perfusional abnormalities. Therefore, the technique is particularly useful in predicting residual pulmonary function.

Adult↗