Search PubMed⌕ Search

Biomedical subjects

A Riva

Publications and source records attributed to A Riva.

At least 109 records · Page 6Linked to original sources
PubMed1997

Anti-proliferative activity of a new class of taxanes (14beta-hydroxy-10-deacetylbaccatin III derivatives) on multidrug-resistance-positive human cancer cells.

Paclitaxel, docetaxel and a series of new analogs synthesized from 14beta-hydroxy-10-deacetylbaccatin III (14-OH-DAB), a natural diterpene closely related to the core synthon of the 2 above prototypes, were tested in vitro for their growth-inhibitory activity on different human cancer cell lines, including some expressing the classic multidrug-resistant (MDR) phenotype (MCF-7 ADRr and CEM VBLr). The 14-OH-DAB derivatives showed enhanced anti-proliferative activity as compared to the parent compounds on the MDR-positive cancer cell lines. Particularly, IDN 5109 showed a 25- to 30-fold higher activity than paclitaxel. The fold change in activity between paclitaxel and analogs (IC50 paclitaxel/IC50 analogs) on the MDR-positive cell lines was calculated and a significant correlation observed. As far as the MDR-negative MDA-MB 231 cells are concerned, docetaxel and IDN 5109 exhibited a more potent activity than paclitaxel. On the basis of the data obtained on cell growth inhibition, we selected the most active compounds to study their effect on the cell cycle. Cell cycle analysis showed that all of the compounds tested were able to induce cell cycle block at G2/M in a concentration-dependent manner. The amount of cell block, measured as a G1/G2 ratio, was correlated significantly (p < 0.001) with apoptosis, as evaluated in the sub-G1 region (% of DNA fragmentation), thereby suggesting that the G2/M-blocked cells underwent apoptosis. To confirm the occurrence of apoptosis in this system, DNA gel agarose electrophoresis was performed and showed the typical ladder pattern.

Antineoplastic Agents, Phytogenic↗
PubMed1997

In vivo footprinting and mutational analysis of the proximal CD19 promoter reveal important roles for an SP1/Egr-1 binding site and a novel site termed the PyG box.

CD19 expression begins at the pro-B cell stage of B cell development. As such it serves as a good prototype for B cell-specific genes whose expression begins shortly after lineage commitment. To understand the molecular mechanisms controlling CD19 gene expression, we isolated and functionally characterized the CD19 promoter using in vivo footprinting, gel shift assays, and transfection studies. Reporter constructs spanning portions of the promoter identified a region between -85 and -200 that produced high levels of reporter gene activity in lymphoid cells. In vivo footprinting identified protected regions over the known high affinity B cell lineage-specific activator protein (BSAP) site, the low affinity BSAP site, a SP1/Egr-1 site termed the CD19 GC box, and two novel sites named the AT box and PyG box. Phorbol ester treatment of a pre-B cell line up-regulated CD19 expression, induced Egr-1, and enhanced the footprint over the GC box. Gel shift assays demonstrated SP1 and Egr-1 binding to the CD19 GC box, while unknown nuclear proteins bound the PyG and AT boxes. Mutations in the AT box or in the BSAP sites did not affect CD19 reporter construct activity, while a mutation of the GC box reduced it modestly, and a PyG box mutation reduced it dramatically. BSAP failed to trans-activate CD19 promoter constructs in B cells or non-B cells, suggesting that cis elements such as the PyG and GC boxes are also necessary for high level CD19 promoter expression.

Antigens, CD19↗
PubMed1997

Patterns of in vitro anti-human immunodeficiency virus type 1 antibody production in long-term nonprogressors.

With the aim of evaluating the specific pattern of in vitro antibody production (IVAP) in human immunodeficiency virus type 1 (HIV-1)-infected long-term non-progressors (LTNPs), we tested 20 subjects who had remained asymptomatic for more than 8 years with a CD4+ cell count higher than 500/microliter and 59 patients at different stages of HIV-1 infection as controls. In cell cultures, IVAP was detected in 14 out of 20 LTNPs (70%), in 5 out of 6 recent seroconverters (83%), and in all the other control patients. Anti-p24 antibody production was significantly lower in LTNPs than in asymptomatic patients with a more recent infection. Recent seroconverters and patients with AIDS did not produce anti-p24 antibodies (P = 0.02). Anti-gp160 antibodies were produced by peripheral blood mononuclear cells from LTNPs in 12/20 cases. CD4+ cell count was significantly higher in IVAP-negative than in IVAP-positive LTNPs (P = 0.013), while the viral load was not significantly different. Specific anti-HIV-1 antibody production did not seem to be a correlate of long-term nonprogression.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A case of meningioma with exceptionally extensive oedema.

We report a meningioma with very extensive surrounding oedema. This finding, along with the age of the patient and other clinical features, made correct diagnosis difficult. The pathophysiology of oedema in general and its exceptional extent in this case are discussed.

Aged↗
PubMed1997

Role of early diagnosis for a noninvasive treatment of pulmonary thromboembolism in leukemic children.

Pulmonary thromboembolism (PTE) in leukemic children undergoing intensive chemotherapy should be promptly recognized so that specific therapy can be started. Our experience with the two cases reported here has led us to propose guidelines for the treatment of initial PTE in a pediatric hematology unit. Two children with leukemia developed PTE, the first during the relapse for acute lymphoblastic leukemia and the second at the onset of acute promyelocytic leukemia. In both cases, the diagnosis of PTE was based on clinical assessment of sudden acute respiratory failure with positive pulmonary perfusional scintigraphy in spite of a negative chest X-ray. The subintensive supervision consisted of instrumental monitoring with the assistance of an intensive care anesthetist. The clinical monitoring was based on the serial registration of respiratory rate, cardiac rate, SaO2 and body temperature. The thrombolytic therapy, together with heparin prophylaxis, was successfully administered in the hematology ward without the need for intensive care support (i.e. mechanical ventilation). The success of the treatment was documented by the criterion of a return to the normal cardiorespiratory parameters a few hours after the start of the thrombolytic treatment. Furthermore, a chest CT scan in case 1 and an arteriography in case 2 confirmed the PTE-related hypoperfusion. On the basis of this experience, the authors point out that in the course of acute respiratory failure in leukemic children, the combination of a negative chest X-ray and a positive pulmonary perfusional scintigraphy (compared whenever possible with ventilatory scintigraphy) in the presence of a negative CT scan could be a reliable diagnostic tool for PTE. This pathology should be treated promptly and with specific therapy to avoid progression to a severe, massive PTE.

Anticoagulants↗
PubMed1997

Synergistic antiproliferative activity of tamoxifen and docetaxel on three oestrogen receptor-negative cancer cell lines is mediated by the induction of apoptosis.

The taxanes are a promising family of anti-tumour drugs that block cell cycle replication by interfering with the microtubule network. The clinical use of these drugs involves some problems related to their low solubility and occurrence of resistance, which is mainly dependent on the multidrug-resistant (MDR) phenotype. To investigate the possible interaction between docetaxel and tamoxifen (TAM), three oestrogen receptor-negative cancer cell lines, MDR- MDA-MB 231, MDR + CEM-VBLr and MCF-7 ADRr, were used. In all three cell lines, the combination of docetaxel and TAM was more effective in terms of growth inhibition than single drug exposure. Isobolic analysis confirmed the presence of synergism in all cell lines when docetaxel was used at 0.2 microM and TAM at a dose equal to or higher than 1 microM. Flow cytometric DNA analysis performed on the three cell lines showed that TAM was able to increase the G2/M blocking activity of docetaxel. This blocking activity was followed by an increased flow cytometric DNA fragmentation suggestive of the presence of apoptosis, which was confirmed by DNA gel fragmentation and morphological analysis. While an antagonistic effect on P-glycoprotein (P-gp) activity may contribute to the synergistic effect of tamoxifen and docetaxel on CEM-VBLr and MCF-7 ADRr, other mechanisms must be involved, as the synergistic effect is also apparent with a P-gp-negative cell line.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

A major human immunodeficiency virus type 1-initiated killing pathway distinct from apoptosis.

We have investigated the relative contribution of apoptosis or programmed cell death (PCD) to cell killing during acute infection with T-cell-tropic, cytopathic human immunodeficiency virus type 1 (HIV-1), by employing diverse strategies to inhibit PCD or to detect its common end-stage sequelae. When Bcl-2-transfected cell lines were infected with HIV-1, their viability was only slightly higher than that of control infections. Although the adenovirus E1B 19-kDa protein has been reported to be a stronger competitor of apoptosis than Bcl-2, it did not inhibit HIV-mediated cell death better than Bcl-2 protein. Competition for Fas ligand or inactivation of the Fas pathway secondary to intracellular mutation (MOLT-4 T cells) also had modest effects on overall cell death during acute HIV infection. In contrast to these observations with HIV infection or with HIV envelope-initiated cell death, Tat-expressing cell lines were much more susceptible (200% enhancement) to Fas-induced apoptosis than controls and Bcl-2 overexpression strongly (75%) inhibited this apoptotic T-cell death. PCD associated with FasR ligation resulted in the cleavage of common interleukin-1beta-converting enzyme (ICE)-protease targets, poly(ADP-ribose) polymerase (PARP) and pro-ICE, whereas cleaved products were not readily detected during HIV infection of peripheral blood mononuclear cells or T-cell lines even during periods of extensive cell death. These results indicate that one important form of HIV-mediated cell killing proceeds by a pathway that lacks the characteristics of T-cell apoptosis. Our observations support the conclusion that at least two HIV genes (env and tat) can kill T cells by distinct pathways and that an envelope-initiated process of T-cell death can be discriminated from apoptosis by many of the properties most closely associated with apoptotic cell death.

Adenovirus E1B Proteins↗
PubMed1997

Downstream effects of splanchnic ischemia-reperfusion injury on renal function and eicosanoid release.

This study examines the hypothesis that intestinal ischemia-reperfusion (I/R) injury contributes to renal dysfunction by altered renal eicosanoid release. Anesthetized Sprague-Dawley rats underwent 60 min of sham or superior mesenteric artery (SMA) occlusion with 60 min of reperfusion. The I/R groups received either allopurinol, pentoxifylline, 1-benzylimidazole, or carrier before SMA occlusion. In vivo renal artery blood flow was measured by Transonic flow probes, the kidneys were then perfused in vitro for 30 min, and the effluent was analyzed for eicosanoid release and renal function. Intestinal I/R caused a twofold increase in the ratio of renal release of thromboxane B2 to prostaglandin E2 and to 6-ketoprostaglandin F1alpha compared with the sham level, with a corresponding 25% decrease in renal sodium and inulin clearance and renal blood flow. Pentoxifylline or allopurinol pretreatment restored renal eicosanoid release and renal sodium and inulin clearance to the sham level but did not alter renal blood flow. Pretreatment with 1-benzylimidazole restored renal function, eicosanoid release, and renal blood flow to sham levels. These data suggest that severe intestinal I/R contributes to the downregulation of renal function. The decrease in renal function is due in part to toxic oxygen metabolites, which occur in the milieu of altered renal eicosanoid release, reflecting a decrease in vasodilator and an increase in vasoconstrictor eicosanoids.

Allopurinol↗
PubMed1997

Autosomal dominant late-onset leukoencephalopathy. Clinical report of a new Italian family.

The adult-onset autosomal dominant leukoencephalopathies are rare disorders. Very few pedigrees have been extensively described and no biochemical or genetic marker has been identified so far. The present study was aimed to characterized an autosomal dominant late-onset leukoencephalopathy occurring in a large Italian kindred. A genealogic method was adopted to ascertain 51 affected individuals among nearly 400 subjects in 8 generations. Medical records were obtained from 11 deceased patients. We personally examined 8 symptomatic and 9 asymptomatic at-risk individuals who underwent a standardized clinical, biochemical, radiological and neurophysiological study. The mean age at onset of the disease was 46.6 years and the mean duration of disease 9.9 years. The clinical picture was characterized by progressive pyramidal and pseudobulbar signs, urinary incontinence and, sometimes, action tremor of the head and/or hands. No relevant mental deterioration was noted. In all the symptomatic and in 1 asymptomatic subject, brain MRI showed marked symmetrical hyperintensity on T2-weighted images of the white matter of the cerebral hemispheres, with constant sparing of the cerebellum. In these subjects, evoked potentials revealed altered central neural conduction. Nerve conduction velocity, biochemical (including lysosomal enzymatic activities) and biopsy (peripheral tissue specimens) examination were normal. The clinical and neuroradiological data are consistent with an autosomal dominant adult-onset leukoencephalopathy whose features are unusual when compared to those previously reported.

Adult↗
PubMed1997

A 3D study of intra and extracellular structures of liver in beta-thalassemia intermedia: an OsO4 maceration analysis.

A scanning electron microscopy study of liver changes has been carried out in three patients affected by beta-thalassemia intermedia (BTI). Applying a new osmium maceration method, recently developed in our laboratory, we had the opportunity to obtain, at SEM, tridimensional images of intra and extracellular structures. Other than the previously reported lesions in BTI, we observed the following pathological findings: disarrangement of the cell structure by a high number of hemosiderin loaded lysosomes; alterations in shape and in diameter of the nuclear pores; presence of apoptotic bodies scattered among the parenchymal cells; deposition of collagen fibers in the space of Disse to form a perihepatocytic dam; enlargement of the sinusoidal endothelial cell fenestrae of the sieve plate. By complete digestion of liver cells, we evidenced a diffuse pericellular fibrosis, made up of interlacing fibrils. Our study evidences some not yet reported morphological lesions in BT. Since patients affected by BTI do not need blood transfusions, these lesions could be considered intrinsic of the disease.

Adult↗
PubMed1997

Docetaxel/doxorubicin/cyclophosphamide in the treatment of metastatic breast cancer.

A pilot phase II study examined the feasibility of 75 mg/m2 of docetaxel (Taxotere) in combination with 50 mg/m2 of doxorubicin and 500 mg/m2 of cyclophosphamide (Cytoxan, Neosar) in the first-line treatment of metastatic breast cancer. This study was designed to evaluate the efficacy and toxicity of the docetaxel/doxorubicin/cyclophosphamide combination both alone and as induction before high-dose chemotherapy, supplemented by autologous peripheral blood stem-cell transplantation. Patients were divided into three groups: one group received 8 courses of docetaxel/doxorubicin/cyclophosphamide; the second received 4 to 6 courses of the same combination with cell sampling, followed by high-dose chemotherapy with autologous peripheral blood stem-cell transplantation; and the third group's regimen was identical to that of the second, with additional granulocyte-colony stimulating factor (G-CSF, filgrastim [Neupogen]). Of 28 patients (149 courses) evaluable for toxicity and response, the overall response rate was 82%, with 5 (18%) complete responses and 18 (64%) partial responses. The most frequent hematologic toxicity was neutropenia; grade 4 neutropenia occurred in 86% of patients, with febrile neutropenia in 9 patients (18%). There was no incidence of infection, possibly because of the administration of oral ciprofloxacin (Cipro) from days 5 to 15 of each cycle. Nonhematologic adverse events were not severe; there was no significant cardiotoxicity. Future randomized trials of docetaxel/doxorubicin/cyclophosphamide as first-line adjuvant therapy of high-risk patients and as induction chemotherapy are in development.

Adult↗
PubMed1997

Docetaxel vs mitomycin plus vinblastine in anthracycline-resistant metastatic breast cancer.

This nonblinded, multicenter, randomized phase III study compares the median time to progression (primary endpoint), response rate, and quality of life, safety, and survival of docetaxel (Taxotere) vs mitomycin (Mutamycin) plus vinblastine (Velban) in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. Patients were randomized to receive an intravenous infusion of either 100 mg/m2 of docetaxel for 1 hour every 3 weeks, or 12 mg/m2 of mitomycin every 6 weeks plus 6 mg/m2 of vinblastine every 3 weeks. This preliminary analysis presents data on 200 patients among 392 patients recruited. Median time to progression was longer in the group treated with docetaxel compared with the mitomycin/vinblastine group (17 vs 9 weeks). The overall response rates were higher with docetaxel (28% vs 13%, respectively), and fewer patients in the docetaxel group had progressive disease as their best overall response (29% vs 48%). As expected, thrombocytopenia was more common in the mitomycin/vinblastine group, and neutropenia occurred more frequently in the docetaxel group. Severe fluid retention in the docetaxel group (8.7%) resulted in treatment discontinuation in 5 patients (5%). Severe thrombocytopenia (12%) and constipation (6%) led to treatment discontinuation in 7 and 3 patients, respectively, in the mitomycin/vinblastine group. Based on this preliminary analysis, docetaxel appears to be equally as safe as and more active than mitomycin/ vinblastine in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. These results are subject to cautious interpretation because this analysis was conducted on the first 200 patients who finished the study treatments, and these preliminary results may underestimate response and overstate treatment discontinuation rates. Thus, the final analysis on the entire patient population is necessary to confirm these preliminary findings.

Adolescent↗
PubMed1997

Docetaxel/doxorubicin/cyclophosphamide in the treatment of metastatic breast cancer.

Preliminary results from phase I trials suggest that the use of docetaxel (Taxotere) and doxorubicin (Adriamycin) is a well tolerated and highly active combination regimen for patients with metastatic breast cancer. The maximum tolerated dose of this combination was 50 mg/m2 of doxorubicin given as an intravenous bolus followed 1 hour later with 75 mg/m2 of docetaxel given as a 1-hour intravenous infusion. Because cardiotoxicity was not observed with this combination, we added cyclophosphamide (Cytoxan, Neosar) in a phase II trial to determine the antitumor activity and tolerability of this 3-drug combination as first-line therapy in patients with metastatic breast cancer. Preliminary results from this study indicate that the Taxotere/ Adriamycin/Cyclophosphamide (TAC) combination produces response rates of up to 80%. However, frequent grade 4 neutropenia was seen in 68% of cycles, febrile neutropenia in 5.5% of cycles, and grade 3 to 4 infection in .8% of cycles. Cardiac toxicity was rare, with 1 case of reversible congestive heart failure (2%), which occurred 2 months after completion of chemotherapy. These preliminary data show that TAC is highly active and that docetaxel did not significantly increase the cardiotoxicity of doxorubicin. Phase III studies in both the first-line and adjuvant settings are warranted.

Adult↗
PubMed1997

Chronic triventricular hydrocephalus: morphological and functional study before and after ventriculoperitoneal shunting.

We have neuroradiologically and neuropsycho-physiologically studied a case of chronic hydrocephalus due to congenital acqueductal stenosis, before and after ventriculoperitoneal shunting. The aims of the study were: 1) to point out the correlation between neuroimaging (Computerized Tomography/Magnetic Resonance Imaging) and mapping of Computerized Spectral Analysis EEG (CSA-EEG); 2) to monitor evoked bioelectrical activity by neurophysiological evaluation of acoustic and visual N1 and P3. Both bioelectrical activity and neuroimaging evaluation showed a considerable recovery of the neurobiological substratum after neurosurgical shunting, while neuropsychological investigation showed a slight improvement in all cognitive tasks.

Adult↗
PubMed1996

Bcl-x rather than Bcl-2 mediates CD40-dependent centrocyte survival in the germinal center.

Both rapid B-cell proliferation and programmed cell death (PCD) occur during the differentiation and selection of B cells within the germinal center. To help elucidate the role of Bcl-x in B-cell antigen selection and PCD within the germinal center, we examined its expression in defined B-cell populations and by immunochemistry of tonsil tissue. Purified B-cell fractions enriched for centrocytes express high amounts of Bcl-x and relatively low amounts of Bcl-2, whereas fractions enriched for centroblasts lack significant levels of both proteins. Consistent with this observation, immunocytochemistry localized Bcl-x within cells scattered throughout the germinal center. Stimulation of tonsil B cells with either CD40 or Staphylococcus aureus Cowan increase bcl-x mRNA and protein levels. Treatment of a cell line with a germinal center phenotype (RAMOS) or the tonsillar B-cell centroblast fraction with CD40 rapidly increased Bcl-x levels and partially rescued B cells from PCD. These data suggest that Bcl-x rather than Bcl-2 may rescue centrocytes during selection in the germinal center.

Apoptosis↗
PubMed1996

Morphological aspects of the vascularization in intraventricular neural transplants from embryo to embryo.

Intraventricular transplants of neural tissues were performed in ovo from embryo to embryo. Fragments of the nervous wall of the optic lobe (tectum) from 14-day chick or 12-day quail embryos (donor) were inserted into the ventricle of the right optic lobe of 6-day chick or 5-day quail embryos (host). Chick-to-chick, chick-to-quail and quail-to-chick grafts were carried out. The vascularization changes occurring in the host tectum and in the grafted neural tissues were analysed under light, transmission, and scanning electron microscopes and by morphometric methods. In the host embryo tectum, the neural graft stimulates a statistically significant increment in vessel density and a vessel sprouting into the ventricle of the optic lobe. The vascular sprouts reach the transplanted tissue and establish connections with its native microvasculature. The chick-to-quail and quail-to-chick grafts, submitted to immunoreaction with a quail-specific antibody which recognizes an antigen (MB1) present on endothelial cells, indicate that re-establishment of the circulation in the graft depends upon anastomoses between host and donor vasculatures and the rapid new growth of host-derived and donor-native vessels. The presence of macrophage-like cells escorting the new-growing vessels suggests that these cells are involved in the host and donor tissue angiogenesis.

Animals↗