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Biomedical subjects

M Magnani

Publications and source records attributed to M Magnani.

At least 127 records · Page 7Linked to original sources
PubMed1993

Glucose-6-phosphate dehydrogenase nucleotide 1311 polymorphism in central Italy (Marche Region).

Glucose-6-phosphate dehydrogenase Mediterranean (G6PD Med) is a common G6PD variant around the Mediterranean Sea characterized by severe enzyme deficiency and B-like electrophoretic mobility. The molecular basis of G6PD Med is a single C-->T transition at nucleotide (NT) 563. A polymorphic site exists in exon 11 of G6PD gene: in the wild-type NT 1311 is a C (1311C), but in some individuals from diverse populations a T (1311T) is present instead. Recent studies suggest that this C-->T transition is in linkage disequilibrium with G6PD Med genotype. In the normal population of Southern Italy (Sicily and Calabria) who is at risk for G6PD Med the NT 1311 allelic frequency is 16.7-20%; no data are available for the other regions. We screened the population of Marche region, Central Italy, in order to know the percentage of this polymorphism in an area not at risk for G6PD Med: we found that the 1311T frequency is about one half of that found in Southern Italy.

Base Sequence↗
PubMed1993

Inhibition of murine retrovirus-induced immunodeficiency disease by dideoxycytidine and dideoxycytidine 5'-triphosphate.

The antiretroviral activity of many nucleoside analogues depends not only on their ability to inhibit the virus reverse transcriptase but also on the specific cellular pools of natural deoxynucleosides and on the level of the enzymes responsible for their phosphorylation. In an attempt to overcome these limitations, we have tested the efficacy of the oral administration of 2',3'-dideoxycytidine (DDC) and the administration of its phosphorylated derivative, 2',3'-dideoxycytidine 5'-triphosphate (DDCTP) encapsulated into autologous red blood cells in a murine retrovirus-induced immunodeficiency model of AIDS (MAIDS). The results obtained showed that both single treatments are quite effective in preventing the typical signs of MAIDS. Combined treatment with both oral DDC and encapsulated DDCTP yields an additive response in some, but not all the parameters investigated. Furthermore, animals receiving the simultaneous administration of DDC and DDCTP show a reduction of animal body weight, a persistent high concentration of IgM, and a high titer of anti-LP-BM5 gag immunoglobulins. Thus, the administration of the same drug in different molecular forms and/or with different delivery systems should be carefully evaluated in preclinical animal models because of the unpredictability of the effects of these treatments from the conclusion drawn by studies on single treatment.

Administration, Oral↗
PubMed1993

Methanol detoxification by enzyme-loaded erythrocytes.

Alcohol oxidase (AlOx) from Pichea pastoris (a methylotrophic yeast) was encapsulated into human and murine erythrocytes up to 2 units/ml of packed cells. This enzyme has a much higher affinity for methanol than for ethanol, thus making the loaded erythrocytes useful cellular bioreactors able to catabolize methanol. Enzyme-loaded erythrocytes showed an increased rate of the hexose-monophosphate-shunt activity and a significant methaemoglobin production. However, the in vivo survival of these cells does not seem to be significantly affected by methanol catabolism. In vivo, mice receiving AlOx-loaded erythrocytes were able to keep the blood methanol concentrations below values that were about 50% of those found in mice receiving unloaded cells and similar amounts of methanol. Thus AlOx-loaded erythrocytes may add an important contribution to the detoxification protocol against methanol poisoning.

Alcohol Oxidoreductases↗
PubMed1992

Oxiracetam prevents the hippocampal cholinergic hypofunction induced by the NMDA receptor blocker AP7.

The intracerebroventricular injection of the N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-7-phosphonoheptanoic acid (AP7) induces an increase of the hippocampal levels of acetylcholine (ACh) which is dose-dependent in the range 1.5-10 micrograms. Similar doses of AP7 failed to affect the ACh content of the striatum. The effect of the i.c.v. administration of 3.5 micrograms AP7 on hippocampal ACh levels was prevented by pretreatment with oxiracetam 100 mg/kg i.p. In the passive avoidance test the i.c.v. administration of 3.5 micrograms of AP7 caused severe amnesia which was antagonized in a dose-dependent manner by the pretreatment with oxiracetam. These results show that oxiracetam prevents the imbalance of cholinergic activity and the amnesia caused by blockade of NMDA receptors. The present study suggests that the hippocampal cholinergic activity is modulated by glutamatergic neuronal pathways and that the functional integrity of both systems is essential for learning and memory processes.

2-Amino-5-phosphonovalerate↗
PubMed1992

Targeting antiretroviral nucleoside analogues in phosphorylated form to macrophages: in vitro and in vivo studies.

A number of nucleoside analogues are active against the infectivity of human immunodeficiency virus (HIV); however, their use is limited by toxic side effects and by limited phosphorylation in the infected cells. In an attempt to overcome these problems, a drug delivery system has been developed. A prototype of these drugs in a form already phosphorylated (2',3'-dideoxycytidine 5'-triphosphate; ddCTP) was encapsulated into erythrocytes. Subsequently, by the addition of Zn, an arrangement of band 3 in clusters was induced (band 3 is the major transmembrane protein in erythrocytes). The immune system recognizes these clusters as nonself, promoting autologous IgG binding and phagocytosis by cells of the monocyte-macrophage lineage. In this way, ddCTP encapsulated into erythrocytes was delivered to macrophage cells, where concentrations greater than 2 microM were found. Addition of ddCTP-loaded erythrocytes to macrophages previously infected by HIV-1 results in almost complete inhibition of HIV production over 3 weeks in culture. Administration of ddCTP-loaded erythrocytes to LP-BM5-infected mice at 10-day intervals over a period of 3 months results in reduction of lymphoadenopathy, splenomegaly, and hypergammaglobulinemia. Thus, the delivery of nucleoside analogues in phosphorylated form is feasible, and selective targeting to virus reservoirs (macrophage cells) can be accomplished by the use of autologous erythrocytes.

Animals↗
PubMed1992

A recombinant human 'mini'-hexokinase is catalytically active and regulated by hexose 6-phosphates.

Mammalian hexokinase type I is a 100 kDa enzyme that has been considered to be evolved from an ancestral 50 kDa yeast-type hexokinase, insensitive to product inhibition, by gene duplication and fusion. According to this model, and based on many experimental data, the catalytic site is associated with the C-terminal half of the enzyme, although an allosteric site for the binding of glucose 6-phosphate could be present on the N-terminal half of the molecule. We have isolated a cDNA clone of hexokinase from a lambda gt11 human placenta library comprising 2658 bp, containing a single open reading frame of 1893 nucleotides, which encodes a truncate form of hexokinase starting from asparagine-287 to the terminal serine-917. This clone was further digested with restriction enzyme NcoI to obtain almost only the C-terminal half of human hexokinase starting from methionine-455 to the terminal amino acid and was overexpressed in active form in Escherichia coli and purified by ion-exchange h.p.l.c. The overexpressed 'mini'-hexokinase was found not only to catalyse glucose phosphorylation, but also to be inhibited by glucose 6-phosphate and other mono- and bis-phosphate sugars exactly like the complete mammalian enzyme. These results suggest that the C-terminal half of human hexokinase, in addition to the catalytic site, also contains the regulatory site and that the evolutionary relationship between the hexokinases should be reconsidered by including the appearance of a regulatory site before the gene duplication.

Amino Acid Sequence↗
PubMed1992

Oxiracetam antagonizes the disruptive effects of scopolamine on memory in the radial maze.

The effects exerted by oxiracetam on the disruption of performance induced by scopolamine in the radial arm maze were investigated in overtrained rats. Scopolamine induced a dose-related decrease in the efficiency of responding and an increase of running time. The effect of the SC injection of 0.2 mg/kg scopolamine on the efficiency of responding was antagonized by the IP administration of 30 mg/kg oxiracetam, while the effect on running time induced by the same dose of scopolamine was not. Physostigmine (0.3 mg/kg SC) antagonized both effects of 0.2 mg/kg scopolamine. Methylscopolamine, at the dose of 0.2 mg/kg SC, was devoid of any effect on both parameters. Increasing the dose of methylscopolamine to 0.63 mg/kg did cause serious peripheral effects which eventually prevented some animals from completing the task. Similar peripheral effects were observed after administration of 0.63 mg/kg scopolamine. The effects of this dose of scopolamine on efficiency and running time were not antagonized by pretreatment with 100 mg/kg oxiracetam. Oxiracetam alone (30 or 100 mg/kg IP) did not modify the performance of previously trained rats. The present results suggest that oxiracetam selectively restores cholinergic mechanisms which are involved in learning and memory.

Animals↗
PubMed1992

In vitro and in vivo toxicity of 2',3'-dideoxycytidine in mice.

3T3 mouse embryo fibroblast cell growth was inhibited in a concentration dependent manner by 2',3'-dideoxycytidine (ddCyd), a strong inhibitor of human immunodeficiency virus. Cell growth inhibition was associated with an increased incorporation of ddCyd into cell DNA. In contrast SP2/0-Ag14 (a mouse myeloma) cell growth is not inhibited by 100 microM ddCyd both in the presence or absence of hypoxanthine and thymidine. Furthermore, in vitro spleen cell proliferation, upon phytohemagglutinin (PHA) addition, was much more affected by ddCyd in C57BL/6 mice than in Swiss albino mice. That indeed ddCyd affects spleen cell proliferation was confirmed by studies on splenocytes obtained from C57BL/6 mice that received ddCyd for 2 weeks in drinking water. These results suggest that ddCyd toxicity in mice is cell and strain dependent and that the toxicity mechanism is related to the incorporation of the drug in cell DNA.

3T3 Cells↗
PubMed1992

[Effects of moderate maternal drinking on some neonatal parameters].

A cross-sectional study was conducted on 2415 mother/newborn pairs, in order to evaluate the relationship between maternal alcohol consumption and birth weight. The results of this study are consistent with previous reports, that pointed out the casual relationship between maternal drinking during pregnancy, and reduction in birth weight. This reduction was evident only on the subset of smokers. A further stratification by the sex of newborn, showed a heavier effect on male newborns, who experienced a significant reduction of 6.2 grams in birth weight for each g of absolute alcohol consumed daily during pregnancy by mother. The findings of this study support the evidence of neonatal functional damages due to alcohol, even at very low doses. A strong increase of early jaundice were found among the outcome of exposed women (OD = 3.30; 95% CI 1.03-10.54).

Alcohol Drinking↗
PubMed1992

Red blood cells as an antigen-delivery system.

The use of adjuvants is usually required to induce strong immunological responses to protein antigens. However, in many cases these adjuvants cannot be extensively applied in human and veterinary vaccinations because of associated inflammatory reactions or granuloma formation. We show here that protein antigens (bovine serum albumin, hog liver uricase, and yeast hexokinase), coupled to autologous red blood cells by way of a biotin-avidin-biotin bridge, elicit an immunological response in mice similar to or higher than that obtained by the use of Freund's adjuvant. Quantities as low as 0.5 micrograms/mouse are high enough to generate these immunological responses. Furthermore, splenocytes of mice immunized by red blood cell-coupled antigens can be used to generate hybridomas secreting monoclonal antibodies. Thus, the delivery of antigens by autologous red blood cells is an effective way to avoid the use of adjuvants for producing anti-peptide antibodies and possibly to generate peptide vaccines.

Animals↗