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Biomedical subjects

G Brandi

Publications and source records attributed to G Brandi.

At least 55 records · Page 3Linked to original sources
PubMed1997

2',3'-Dideoxycytidine cytotoxicity in human macrophages.

Human macrophages when cultured for several weeks in the presence of therapeutically relevant 2',3'-dideoxycytidine (ddC) concentrations show a time-dependent decay in mitochondrial DNA content. This decay is associated with a reduction of Rhodamine 123 fluorescence, a marker for mitochondrial membrane potential suggesting that impairment of mitochondrial functions occurs. Mitochondrial metabolic impairment was confirmed by direct evaluation of lactate production, which is markedly increased in cells treated with ddC. The activity of protein kinase C and intracellular free Ca2+ upon addition of phorbol 12-myristate 13-acetate (PMA) were lower in the drug-treated cells compared to controls. A 50% reduction in O2-release was also found upon PMA stimulation. Fluorescent latex beads, yeast and bacteria phagocytosis were normal, but intracellular bacteria killing was markedly impaired in ddC-exposed macrophages. Thus, ddC exerts a delayed mitochondrial toxicity also on differentiated macrophages with impairment of several metabolic properties and O2 production causing a reduced ability of these phagocytic cells to kill phagocytosed bacteria.

Anti-HIV Agents↗
PubMed1997

Targeting antiviral nucleotide analogues to macrophages.

Macrophages are important target cells for human immunodeficiency virus type 1 (HIV-1) infection. We have developed a drug targeting system for the selective delivery of phosphorylated nucleoside analogues to these phagocytosing cells. This system is based on the possibility of encapsulating the phosphorylated drugs into autologous erythrocytes and on the subsequent selective modification of their membranes to promote macrophage recognition and phagocytosis. Targeted delivery of phosphorylated nucleoside analogues to human, feline, and murine macrophages inhibits the infectivity of HIV-1, feline immunodeficiency virus, and LP-BM5 viruses more efficiently than the administration of the corresponding nucleoside analogues. In vivo administration of 2',3'-dideoxycytidine 5'-triphosphate (ddCTP) encapsulated into autologous erythrocytes to LP-BM5-infected mice was found to reduce infectivity and disease progression. Furthermore, the simultaneous administration of AZT or ddC produced additive antiviral effects. The possibility of using red cells as drug targeting systems was useful for the design, synthesis, and delivery of new antiviral nucleoside analogues. As a prototype of these new drugs, di-(thymidine-3'-azido-2',3'-dideoxy-D-riboside)-5'-5'-p1-p2-pyrophospha te (AZTp2AZT) was prepared. Although this drug in solution has the same antiviral activity as AZT, when administered encapsulated into erythrocytes it was several times more efficient in inhibiting the infectivity of human, feline, and murine immunodeficiency viruses. Thus, the availability of a drug targeting system for the selective delivery of antivirals to macrophages offers an additional possibility for the development of new drugs and of new combination antiviral therapies.

Animals↗
PubMed1997

Modulation of host cell activation during feline immunodeficiency virus (FIV) infection.

The authors describe the mitogenic effect of feline immunodeficiency virus (FIV) infection (1) in vitro, on feline resting peripheral blood lymphocytes (PBL), and (2) in vivo, in experimentally infected cats. Infected PBL were more readily recruited than non-infected PBL, into the G1 phase of the cell cycle and showed increased expression of the specific cell-cycle markers p53 and p56. In-vivo lymphocyte activation following FIV infection was demonstrated by increased germinal centre activity in infected lymph nodes, together with a high expression of CD30, a B-cell activation marker. These results suggest that early events in FIV infection include modulation of host cell activation. Possible implications for pathogenesis are discussed.

Animals↗
PubMed1997

Increased microbicidal activity of human monoblastoid cells upon long-term exposure to dideoxycytidine.

2',3'-Dideoxycytidine (ddC) is a nucleoside analogue currently used in AIDS therapy. We had previously found that long term exposure of U937 human monoblastoid cells to ddC induces the selection of drug-resistant cells (U937-R). In the present work we investigated some important biochemical properties and functional activities of these resistant cells. The results obtained show that U937-R maintained the properties of cell aggregation, adhesion and differentiation. Basal respiration, protein kinase C activity, superoxide anion release and intracellular free calcium were all increased in the drug-resistant line. Phagocytosis of fungi (Candida albicans) and bacteria (Staphylococcus aureus and Salmonella anatum) were similar in U937 and U937-R cells. Killing of C. albicans was significantly higher in drug-resistant cells (29.07 +/- 2.23% of killing vs 19.07 +/- 2.01 in the control; p < 0.001). Similarly, the bacterial killing was enhanced in U937-R cells (34.07 +/- 8.06% vs 22.60 +/- 4.41% in the control; p < 0.05). Thus, the results presented in this paper provide evidence of an increased microbicidal activity of human monocytic cells upon long term exposure to ddC, most likely due to an increased oxidative metabolism.

Blood Bactericidal Activity↗
PubMed1997

FIV induced encephalopathy: early brain lesions in the absence of viral replication in monocyte/macrophages. A pathogenetic model.

FIV induced encephalopathy represents a model for the study of the neuropathogenesis of AIDS. It has yet to be determined whether massive viral replication is a prerequisite for the development of early brain lesions. Using a drug delivery system developed by us, we have shown that early encephalic lesions appear in FIV infected subjects even when viral transport within the brain has been markedly reduced or blocked.

Acute Disease↗
PubMed1997

Rectal cell proliferation and colon cancer risk in patients with hypergastrinaemia.

BACKGROUND: The influence of gastrin on the colonic mucosa is still uncertain. Some authors have suggested a stimulating effect on the growth of normal and malignant colonic epithelium, while others have shown no association between gastrin and neoplastic development. AIMS: To evaluate the effect of gastrin on colorectal cell proliferation, patients with chronic endogenous hypergastrinaemia underwent proctoscopy. Biopsy specimens were taken in order to study rectal cell kinetics. PATIENTS AND CONTROLS: Ten patients with chronic autoimmune gastritis (CAG), six patients with Zollinger-Ellison syndrome (ZES), and 16 hospital controls took part in this study. Patients with CAG and ZES had basal serum gastrin concentrations significantly higher than controls (p < 0.001). METHODS: Immunohistochemistry was performed on 3 microns sections of rectal biopsy specimens incubated with 5'-bromodeoxyuridine. RESULTS: The percentage of proliferating cells in the entire crypts (overall labelling index) was similar in all the groups. However, the labelling frequency in the upper two fifths of the glands (phi h value) was significantly higher in patients with CAG or ZES compared with controls (p < 0.01 in both patient groups versus controls). CONCLUSIONS: Endogenous hypergastrinaemia is associated with rectal cell proliferation defects, similar to those observed in conditions at high risk for colon cancer. The effect of the increased serum concentrations of gastrin on the colorectal mucosa after treatment with drugs inhibiting gastric acid secretion should be investigated.

Adult↗
PubMed1997

Drinking habits as cofactors of risk for alcohol induced liver damage. The Dionysos Study Group.

BACKGROUND: The Dionysos Study is a cohort study of the prevalence of chronic liver disease in the general population of two northern Italian communities. It included 6917 subjects, aged 12-65 (69% of the total population). AIMS: The aim of this part of the study was to examine the relationship of daily alcohol intake, type of alcoholic beverage consumed, and drinking patterns to the presence of alcohol induced liver damage in an open population. PATIENTS AND METHODS: 6534 subjects, free of virus related chronic liver disease and participating in the first cross-sectional part of the study, were fully examined. Each subject underwent: (a) medical history and physical examination, (b) evaluation of alcohol intake using an illustrated dietary questionnaire, and (c) routine blood tests. More invasive diagnostic procedures were performed when indicated. RESULTS: Multivariate analysis showed that the risk threshold for developing either cirrhosis or non-cirrhotic liver damage (NCLD) was ingestion of more than 30 g alcohol per day in both sexes. Using this definition, 1349 individuals (21% of the population studied) were at risk. Of these, only 74 (5.5% of the individuals at risk) showed signs of liver damage. The prevalence of "pure" alcoholic cirrhosis was 0.43% (30 of 6917), representing 2.2% of the individuals at risk, with a ratio of men to women of 9:1, while 44 (3.3% of the individuals at risk) showed persistent signs of NCLD. After 50 years of age, the cumulative risk of developing both NCLD and cirrhosis was significantly higher (p < 0.0001) for those individuals who regularly drank alcohol both with and without food than for those who drank only at mealtimes. CONCLUSIONS: Our data show that in an open population the risk threshold for developing cirrhosis and NCLD is 30 g ethanol/day, and this risk increases with increasing daily intake. Drinking alcohol outside mealtimes and drinking multiple different alcoholic beverages both increase the risk of developing alcohol induced liver damage.

Adolescent↗
PubMed1996

Low levels of hydrogen peroxide and L-histidine induce DNA double-strand breakage and apoptosis.

The results presented in this study demonstrate that L-histidine triggers a lethal response in U937 cells exposed to nontoxic, albeit growth-inhibitory, levels of H2O2. Treatment for 1 h with the cocktail H2O2/L-histidine promotes the formation of a low level of DNA double-strand breaks that are rapidly rejoined, and this process is followed by secondary DNA fragmentation at about 7 h of post-treatment incubation, at which time cells are still viable. The appearance of oligonucleosomal DNA fragments associated with the detection of morphological changes typical of apoptosis strongly suggests that a portion of the cells was undergoing an apoptotic process. The relative level of cells with fragmented chromatin never exceeded 15-20% throughout the 20 h post-treatment incubation. Treatment with high concentrations of H2O2 in the presence of L-histidine was found to trigger necrotic cell death. The results presented in this paper provide further experimental evidence in support of the notion that DNA double-strand breaks mediate the lethal effects of the cocktail H2O2/L-histidine and suggest that this type of DNA lesion can promote both apoptotic and necrotic cell death, depending on the concentration of the oxidant.

Apoptosis↗
PubMed1996

Inhibition of murine AIDS by combination of AZT and dideoxycytidine 5'-triphosphate.

SUMMARY: A combination of antiretroviral drugs acting on different cell types (lymphocytes and macrophages) was evaluated in a murine retrovirus-induced immunodeficiency model of AIDS (MAIDS). In a first experiment, C57BL/6 mice were infected with a single i.p. administration of LP-BM5 and treated with 0.125 or 0.25 mg/ml AZT in drinking water for 3 months. AZT treatment was found to reduce lymphadenopathy (60 and 65 percent, respectively), splenomegaly (37 and 50 percent, respectively), and hypergammaglobulinemia (6 and 50 percent, respectively). Furthermore, at the highest AZT concentration, BM5d proviral DNA content in lymph nodes and in the spleen showed a reduction of 78 and 70 percent, respectively, compared to untreated animals. In a second experiment, infected mice were treated with AZT (0.25 mg/ml in drinking water) and with 2',3'-dideoxycytidine 5'-triphosphate (ddCTP) encapsulated into autologous erythrocytes for macrophage protection. Combined treatments resulted in a further reduction of lymphadenopathy (a further 33 percent with respect to the single treatment of AZT) and splenomegaly (a further 28 percent respect to the single treatment of AZT) but not of gammaglobulinemia. Proviral DNA in lymph nodes and spleen showed a reduction of 82 and 77 percent, respectively, compared to infected mice. Stimulation index of T cells was also significantly increased in animals receiving both treatments versus AZT only. In conclusion, the selective administration of antiviral drugs that preferentially protect different cell types seems to provide additional advantages compared to single-agent therapy.

Animals↗
PubMed1996

Synthesis and targeted delivery of an azidothymidine homodinucleotide conferring protection to macrophages against retroviral infection.

The infectivity and replication of human (HIV-1), feline (FIV), and murine (LP-BM5) immunodeficiency viruses are all inhibited by several nucleoside analogues after intracellular conversion to their triphosphorylated derivatives. At the cellular level, the main problems in the use of these drugs concern their limited phosphorylation in some cells (e.g., macrophages) and the cytotoxic side effects of nucleoside analogue triphosphates. To overcome these limitations a new nucleoside analogue homodinucleotide, di(thymidine-3'-azido-2',3'-dideoxy-D-riboside)-5'-5'-p1-p2-pyrophosphat e (AZTp2AZT), was designed and synthesized. AZTp2AZT was a poor in vitro inhibitor of HIV reverse transcriptase, although it showed antiviral and cytotoxic activities comparable to those of the parent AZT when added to cultures of a HTLV-1 transformed cell line. AZTp2AZT encapsulated into erythrocytes was remarkably stable. Induction of erythrocyte-membrane protein clusterization and subsequent phagocytosis of AZTp2AZT-loaded cells allowed the targeted delivery of this impermeant drug to macrophages where its metabolic activation occurs. The addition of AZTp2AZT-loaded erythrocytes to human, feline, and murine macrophages afforded almost complete in vitro protection of these cells from infection by HIVBa-L, FIV, and LP-BM5, respectively. Therefore, AZTp2AZT, unlike the membrane-diffusing azidothymidine, acts as a very efficient antiretroviral prodrug following selective targeting to macrophages by means of loaded erythrocytes.

Animals↗
PubMed1996

Hydrogen peroxide mediates the killing of U937 tumor cells elicited by pharmacologically attainable concentrations of ascorbic acid: cell death prevention by extracellular catalase or catalase from cocultured erythrocytes or fibroblasts.

Pharmacologically attainable concentrations of ascorbic acid are highly toxic for U937 cells (a human promyelocytic cell line), and this response appears to be mediated by H2O2. This inference finds experimental support in the following observations: 1) toxic levels of H2O2 are readily generated upon dissolution of survival-range concentrations of ascorbic acid in the culture medium; 2) the lethal effects elicited by ascorbic acid or reagent H2O2 are prevented by the addition of either catalase or the intracellular iron chelator o-phenanthroline and are characterized by similar temporal dependence; 3) U937 cells resistant to hydrogen peroxide are cross-resistant to ascorbic acid; 4) under the conditions utilized in this study, H2O2 and ascorbate promote similar modes of cell death (i.e., necrosis); and 5) cell killing provoked by H2O2 or ascorbate is an inverse function of cell density and is suppressed by coculturing U937 target cells with human erythrocytes (at a density far below that present in the blood) and human fibroblasts. Cytoprotection was not observed using catalase-depleted erythrocytes. Taken together, these results strongly suggest that H2O2 is entirely responsible for the ascorbate-induced U937 cell killing. We therefore propose that it is unlikely that the vitamin damages or kills tumor cells of normal tissues in vivo via the H2O2 based mechanism, because the oxidant would be removed promptly by the neighboring cells.

Ascorbic Acid↗
PubMed1995

2',3'-Dideoxycytidine metabolism in a new drug-resistant cell line.

2',3'-Dideoxycytidine (ddC) is a nucleoside analogue that inhibits human immunodeficiency virus type 1 (HIV-1) replication in vitro and is currently used in the therapy of acquired immune deficiency syndrome (AIDS). This compound exerts a delayed cytotoxicity due to inhibition of mitochondrial DNA (mDNA) synthesis. Long-term exposure of U937 human monoblastoid cells to ddC resulted in a time- and concentration-dependent decrease in mDNA content and Rhodamine 123 fluorescence. However, after 2 months on 0.1 microM ddC, a drug-resistant cell line (U937-R) with 66% of the normal amount of mDNA was isolated. ddC transport in U937 and U937-R cell lines was similar. In contrast, U937-R accumulated ddC phosphorylated derivatives at a much lower rate and to a reduced concentration into acid-soluble material. The rate of 2',3'-dideoxycytidine 5'-triphosphate (ddCTP) formation in U937-R cells was almost one-third of that measured in normal cells, although the rate of ddCTP catabolism was similar in both cell lines. Dideoxyliponucleotide (ddCDP-choline and ddCDP-ethanolamine) formation was also much slower (between one-half and one-third as fast) in U937-R than in control cells, although catabolism occurred at similar rates. ddC was phosphorylated by a cytoplasmic deoxycytidine kinase in both cell lines. This enzyme showed Km values for ddC of 80 +/- 7 and 140 +/- 9 microM in U937 and U937-R cells respectively. Furthermore, Vmax was 12 +/- 1.1 and 7.8 +/- 0.5 pmol/min per mg of protein in U937 and U937-R. Thus resistance to ddC toxicity may be due to cells' decreased ability to accumulate intracellular ddC anabolites, which may depend on cytoplasmic deoxycytidine kinase.

Biological Transport↗
PubMed1995

Colorectal cancer in patients with ulcerative colitis. A prospective cohort study in Italy.

BACKGROUND: The aim of this study was to assess the development of dysplasia or cancer in patients with ulcerative colitis and to determine the effectiveness of colonoscopy and biopsy follow-up in colon cancer surveillance. METHODS: From 1980 to 1986, 65 patients who had ulcerative colitis for 7 years or more participated in a surveillance program of colonoscopy and biopsy. This cohort was followed until December 1992. Forty-nine patients (75.4%) had extensive colitis and 16 (24.6%) left-sided colitis. The mean disease duration was 17.2 years. Three hundred four colonoscopies were performed. During each endoscopy, random biopsies were performed. RESULTS: Seven patients had definite dysplasia of the colorectal mucosa. Four of them had high grade lesions and underwent surgery. In all of these patients, colon cancer (3 Dukes' Stage A, 1 Dukes' Stage B) was found. No cancer was found in the other patients. Pedunculated adenomas were excised from 6 other patients during colonoscopy. When dysplasia was diagnosed, these patients were older than those who were dysplasia free, whereas the age at onset of colitis was significantly higher in the former (P < 0.01). Fifteen patients discontinued follow-up. Two of them developed colon cancer diagnosed at an advanced stage. CONCLUSIONS: Dysplasia, especially of high grade, is a marker of colon cancer risk in patients with longstanding ulcerative colitis. Intensive colonoscopy and biopsy surveillance can lead to the diagnosis of colon cancer at a potentially curable stage. In this series, older age appeared to be an additional risk factor. A careful selection of patients with ulcerative colitis seems mandatory to minimize the cost and optimize the benefit of colon cancer surveillance programs.

Adult↗
PubMed1995

Effect of antiviral treatments on the bone marrow in murine aids.

Blood cytopenia is a common feature in HIV infection, occurring in up to 70% of patients with AIDS. Since at present it is not clear to what extent this is intrinsic to HIV infection or due to opportunistic infections and antiretroviral agents we have investigated the long-term effects of conventional and new antiviral drugs on the bone marrow of normal and immunodeficient mice. The results show that azidothymidine (AZT), dideoxycytidine (DDC) and dideoxycytidine 5'-triphosphate (DDCTP) alone or in combination are all effective in inhibiting the expression of the retroviral protein Pr60gag in bone marrow cells. However, DDCTP was the most effective in preventing bone marrow cytopenia. Combined treatments of AZT plus DDCTP result in a reduction in erythroid precursors compared to that resulting from DDCTP administration, while DDC plus DDCTP results in a differential cell count similar to that found in uninfected mice. Thus, the bone marrow in murine AIDS may prove useful as a model for therapy of retroviral infections and for treating blood cytopenias.

Animals↗
PubMed1995

Flow-triggering reduces inspiratory effort during weaning from mechanical ventilation.

OBJECTIVE: To investigate whether a new flow-triggered (FT) system can reduce the patient's inspiratory effort compared to a traditional pressure-triggered (PT) system during weaning from mechanical ventilation. DESIGN: Prospective study. SETTING: Intensive care unit of a General Hospital. PATIENTS AND PARTICIPANTS: 10 mechanically ventilated patients, without chronic airway disease, ready to wean. MEASUREMENTS: Minute ventilation, breathing pattern, lung mechanics, inspiratory work of breathing (WI) and pressure time product (PTP) of Ppl were obtained in two conditions: 1) unsupported spontaneous breathing through the ventilator circuit (SB); 2) spontaneous breathing with continuous positive airway pressure set at 5 cmH2O (CPAP). Two triggering systems, namely PT and FT, were used in each condition. RESULTS: Though there was no change in breathing pattern, minute ventilation, and lung mechanics, the magnitude of the inspiratory effort decreased significantly with FT compared to PT in both instances. The added resistance (total flow resistance minus pulmonary resistance) decreased by 37% on average when FT replaced PT. PTP decreased, on average, 27% and 15% during SB and CPAP, respectively, with FT compared to PT (p < 0.05). A similar significant decrease was observed in WI. CONCLUSION: The new FT system, i.e. flow-by system, reduces the unintentional ventilatory workload upon the patients' inspiratory muscles compared to traditional PT system during weaning from mechanical ventilation.

Adult↗
PubMed1995

Diffusion of thermophilic Campylobacter in the Pesaro-Urbino area (Italy) from 1985 to 1992.

The results of research on the spreading of campylobacter in the Pesaro-Urbino area carried out from 1985 to 1992 are presented. Materials of different origin were examined: 822 samples of human faeces, 533 animal rectal swabs, 192 samples of domestic sewage, 48 of river water, 96 of sea water and 632 of various types of food. Two hundred and nine strains of campylobacter were isolated (9%), most of which were Campylobacter jejuni (80%), with particular frequency in food products (chicken carcass 45.7%, ground meat and sausage 18.1%) and in river water (31.3%). In contrast, the samples of sea water and dairy cheese products were always negative. It may be concluded that the spreading of campylobacter in the Pesaro-Urbino area is mainly associated with food products of animal origin. Therefore, better controls in the processing of these products may be necessary.

Animals↗