Search PubMed⌕ Search

Biomedical subjects

L Rossi

Publications and source records attributed to L Rossi.

At least 181 records · Page 10Linked to original sources
PubMed1996

Encapsulation, metabolism and release of 2-fluoro-ara-AMP from human erythrocytes.

2-Fluoro-ara-AMP (fludarabine phosphate) is a purine analogue with anti-neoplastic activity in lymphoproliferative malignancies. Fludarabine phosphate activity and toxicity is schedule-dependent; multiple daily administrations (for five days) are more effective than single dose. We have encapsulated fludarabine phosphate in human erythrocytes and found that it is slowly released as fludarabine for more than four days. Encapsulated fludarabine phosphate does not affect erythrocyte metabolism and is rapidly converted by erythrocyte enzymes both to fludarabine with a Km of 0.4 mM and a Vmax of 20 nmol/min per g hemoglobin and to fludarabine diphosphate and triphosphate. The apparent Km for fludarabine monophosphate in the phosphorylation reaction was 0.4 mM and the Vmax 40 nmol/min per g hemoglobin. In the phosphorylation of 2-fluoro-ara-AMP to the di- and triphosphate derivatives, ATP was the phosphate donor with apparent Km of 0.12 and 1.0 mM, respectively. During incubations of 2-fluoro-ara-AMP-loaded erythrocytes at 37 degrees C fludarabine was found in equilibrium between the erythrocyte and the culture medium suggesting that permeation of the erythrocyte membrane is not rate-limiting. Thus, fludarabine phosphate-loaded erythrocytes might be used as a slow-delivery system for fludarabine administration in the treatment of lymphoid malignancies.

Adenosine Diphosphate↗
PubMed1996

Inhibition of murine AIDS by reduced glutathione.

The imbalance of the redox state in cells and body fluids in HIV-1-infected patients may result in progression of the disease as well as in immunologic disfuctions. In this report, we have evaluated whether the direct administration of high doses of reduced glutathione (GSH) exerts any antiviral activity and/or improves immune functions in a murine immunodeficiency animal model. Intramuscular administration of 50 or 100 mg GSH/mouse for five consecutive days weekly to LP-BM5-infected mice did not show local or systemic signs of acute toxicity. During the first 3 weeks from infection, a period in which clinical signs of disease were not yet detectable, GSH significantly reduced the viral load in lymph nodes and spleen as evaluated by a PCR semiquantitative assay of the proviral DNA content. At 10 weeks a GSH concentration-dependent reduction of splenomegaly, lymphadenopathy and hypergammaglobulinemia was evident in all treated mice. Evaluation of proviral DNA content showed that GSH was effective in inhibiting LP-BM5 infectivity in lymph nodes, spleen, and bone marrow at 100 mg/day, while it was less effective when administered at 50 mg/day. At 10 weeks some animals receiving the highest GSH dose died, thus only the mice receiving 50 mg GSH were followed up to 15 weeks without signs of toxicity. In this case, almost not significant differences among infected untreated or treated animals were observed. Thus, GSH is effective in reducing the proviral DNA load in the first period of infection. These data and the failure of sulfhydril supplementation to further counteract the progression of disease after 10 weeks of infection suggest that combinations of GSH and other antiviral agents may be useful for improving current antiviral therapies.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Age-related changes in the binding and uptake of Cu, Zn superoxide dismutase in rat liver cells.

The present paper reports the effect of aging on receptor mediated endocytosis of Cu, Zn superoxide dismutase in rat liver cells. The fate of bovine Cu, Zn superoxide dismutase conjugated to colloidal gold was followed by electron microscopy in young (2 months) and old (24 months) rats in situ, in vivo and in vitro experiments. The use of different models for the study of the binding and internalization of the enzyme allowed to discriminate the contribution of each different liver cell type. The data obtained demonstrate that aging of the liver affects binding and uptake of this enzyme. In particular both the number of binding sites and the rate of internalization were depressed in old rats. Therefore, the hypothesis of therapeutic application of superoxide dismutase for age-related diseases needs to be revalued in view of the fact that receptor-mediated endocytosis of this protein is a mechanism affected by senescence.

Age Factors↗
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

Azidothymidine homodinucleotide-loaded erythrocytes and bioreactors for slow delivery of the antiretroviral drug azidothymidine.

A new Azidothymidine derivative, di-(thymidine-3'- azido-2',3'-dideoxy-D-riboside)-5'-5'-p1-p2-pyrophosphate (AZTp2AZT), was encapsulated in human erythrocytes according to a conservative procedure of hypotonic shock-isotonic resealing and reannealing. Like in erythrocyte lysates supplemented with 1 mM ATP, intact red cells too were found to convert AZTp2AZT to 3'-Azido-3'-deoxythymidine which was then released linearly in plasma. The major metabolic pathway involved in this conversion was the symmetrical hydrolysis of AZTp2AZT to yield two 3'-Azido-3'- deoxythymidine-5'-phosphate molecules which were then dephosphorylated to 3'-Azido-3'-deoxythymidine. At late times of incubation, also a limited asymmetrical hydrolysis of AZTp2AZT became apparent in the intact erythrocytes, yielding 3'-Azido-3'-deoxythymidine-5'-diphosphate that was then converted to the triphosphorylated derivative. Therefore, erythrocytes loaded with AZTp2AZT act "in vitro" as bioreactors ensuring sustained and potentially useful release of 3'-Azido-3'-deoxythymidine.

Dideoxynucleotides↗
PubMed1996

Integration of complete transferred DNA units is dependent on the activity of virulence E2 protein of Agrobacterium tumefaciens.

Agrobacterium tumefaciens transfers transferred DNA (T-DNA), a single-stranded segment of its tumor-inducing (Ti) plasmid, to the plant cell nucleus. The Ti-plasmid-encoded virulence E2 (VirE2) protein expressed in the bacterium has single-stranded DNA (ssDNA)-binding properties and has been reported to act in the plant cell. This protein is thought to exert its influence on transfer efficiency by coating and accompanying the single-stranded T-DNA (ss-T-DNA) to the plant cell genome. Here, we analyze different putative roles of the VirE2 protein in the plant cell. In the absence of VirE2 protein, mainly truncated versions of the T-DNA are integrated. We infer that VirE2 protects the ss-T-DNA against nucleolytic attack during the transfer process and that it is interacting with the ss-T-DNA on its way to the plant cell nucleus. Furthermore, the VirE2 protein was found not to be involved in directing the ss-T-DNA to the plant cell nucleus in a manner dependent on a nuclear localization signal, a function which is carried by the NLS of VirD2. In addition, the efficiency of T-DNA integration into the plant genome was found to be VirE2 independent. We conclude that the VirE2 protein of A. tumefaciens is required to preserve the integrity of the T-DNA but does not contribute to the efficiency of the integration step per se.

Agrobacterium tumefaciens↗
PubMed1996

An epidemiological study of canine filarioses in north-west Italy: what has changed in 25 years?

A field survey aimed at updating knowledge of the distribution and prevalence of filarial infections in the Piedmont region was undertaken. Blood samples were collected from 2628 dogs (10-15 dogs/100 km2) which had remained in the local area, were kept in the open overnight, were more than 2 years old and had not previously been treated with microfilaricidal drugs. Infection was diagnosed by a modified Knott test. Comparison of the results with those from a similar survey carried out 25 years ago showed a 3-fold increase in the size of the endemic area, with the colonization of new habitats, and a 4-fold increase in the prevalence of Dirofilaria immitis infection.

Animals↗
PubMed1996

Selenium, zinc, and thyroid hormones in healthy subjects: low T3/T4 ratio in the elderly is related to impaired selenium status.

Iodothyronine 5' deiodinase, which is mainly responsible for peripheral T3 production, has recently been demonstrated to be a selenium (Se)-containing enzyme. The structure of nuclear thyroid hormone receptors contains Zinc (Zn) ions, crucial for the functional properties of the protein. In the elderly, reduced peripheral conversion of T4 to T3 with a lower T3/T4 ratio and overt hypothyroidism are frequently observed. We measured serum Se and RBC GSH-Px (as indices of Se status), circulating and RBC Zinc (as indices of Zn status), thyroid hormones and TSH in 109 healthy euthyroid subjects (52 women, 57 men), carefully selected to avoid abnormally low thyroid hormone levels induced by acute or chronic diseases or calorie restriction. The subjects were subdivided into three age groups. To avoid under- or malnutrition conditions, dietary records were obtained for a sample of 24 subjects, randomly selected and representative of the whole population for age and sex. Low T3/T4 ratios and reduced Se and RBC GSH-Px activity were observed only in the older group. A highly significant linear correlation between the T3/T4 ratio and indices of Se status was observed in the older group of subjects (r = 0.54; p < 0.002, for Se; r = 0.50; p < 0.002, for RBC GSH-Px). Indices of Zn status did not correlate with thyroid hormones, but RBC Zn was decreased in older as compared with younger subjects. We concluded that reduced peripheral T4 conversion is related to impaired Se status in the elderly.

Adult↗
PubMed1996

Environmental and human influence on the ecology of Trichinella spiralis and Trichinella britovi in Western Europe.

Surveys on Trichinella parasites in domestic and sylvatic animals collected in France, Italy, and in the Extremadura region of Spain showed that the distribution of Trichinella spiralis and Trichinella britovi is influenced by both environmental and human behaviour factors. In France, both Trichinella species are prevalent in the fox population from mountain areas and natural parks but are infrequent in wild boars (< 0.001%). In Italy, only T. britovi is present in sylvatic animals (foxes, wolves, and mustelids) living 500 m above sea level. This species is rare in wild boars (< 0.001%) in that area. Sylvatic trichinellosis is found in only 24% and 34% of French and Italian territory, respectively, while lowland areas may generally be considered Trichinella-free, because the domestic cycle is absent. The ecology of T. spiralis and T. britovi in the Extremadura shows a different picture from that observed in France and Italy because of the presence of both domestic and sylvatic cycles. The domestic cycle not only allows the maintenance of T. spiralis in the domestic environment, but it also has a great impact on the prevalence in wild boar populations. It does not influence the prevalence in vulpine populations. These data suggest (1) that domestic trichinellosis occurs only in rural areas of Western Europe in association with traditional swine-rearing practices, but not in industrialized pig farms; (2) that sylvatic trichinellosis occurs only in natural habitats which, in Western Europe, are widespread in mountain areas; (3) that the fox is the primary reservoir in the sylvatic cycle, where the parasite is maintained in a closed circuit and (4) that among sylvatic animals T. spiralis is present at lower altitude than is T. britovi.

Animals↗
PubMed1996

Metal substrates influence the release of glycosaminoglycan and transforming growth factor beta by human bone cells.

Bone cells derived from human jaw were isolated from explants and grown in vitro. Subcultures were cultured on plastic (control) and metal substrates for 24 and 48 hours in medium containing 3H-glucosamine and labeled glycosaminoglycan (GAG) accumulation was measured. In bone cells cultured on metal substrates there was an evident reduction in the synthesis and secretion of radiolabeled macromolecules compared to bone cells cultured on plastic. Moreover, the accumulation of single GAG classes was specific for each substrate tested. The results showed that titanium was the only metal substrate studied in which the percentage of individual GAG classes remained the same as control cultures. GAG reduction was due to a decreased synthesis and not to an increased degradation as shown by the decrement of exoglycosidase activity. The metals also reduced the activity of transforming growth factor beta (TGF beta), measured using interleukin-1 assay method, a factor involved in the various phases of bone remodeling; in this case, too, cells grown on titanium showed the highest TGF beta activity compared to the other metal substrates studied. The results indicate that the substrate to which the cells adhere do exhibit specific differences in GAG composition and TGF beta activity. The differences observed may be important during in vivo events such as guided tissue regeneration and bone deposition.

Acetylglucosaminidase↗
PubMed1996

Tetrasomy 8 and t(1;11)(p32;q24) in acute myelo-monocytic leukemia with extensive leukemic cutaneous involvement.

We report a case of tetrasomy 8 in a patient suffering from acute myelomonocytic leukemia with extensive leukemic cutaneous infiltration. In all metaphases analyzed t( I;11)(p32;q24) was concomitantly observed. Similarly to other cases with tetrasomy 8, the patient showed monocytic involvement and poor response to chemotherapy. We conclude that this kind of cytogenetic aberration is associated with distinct morphologic and clinical features.

Aged↗
PubMed1996

N-[5-nitro-2-furfurylidene]-3-amino-2-oxazolidinone activation by the human intestinal cell line Caco-2 monitored through noninvasive electron spin resonance spectroscopy.

The pathways participating in the metabolism of the nitrofuran antimicrobial drug N-[5-nitro-2-furfurylidene]-3-amino-2-oxazolidinone (furazolidone) in intact cells were investigated in the human intestinal cell line Caco-2. One-electron reduction of furazolidone led to the formation of a free radical intermediate that could be monitored in dense cell suspensions by noninvasive electron spin resonance spectroscopy. The effects of enzyme inhibitors on the kinetics of radical production and decay were used to estimate the relative contribution of different enzymes to the reductive activation of the drug. Although many enzymes are known to reduce nitrofurans in vitro (e.g., xanthine oxidase, aldehyde oxidase, DT-diaphorase, mitochondrial redox chain components), their contributions were insignificant in living Caco-2 cells. The first reducing equivalent required for the formation of the nitroanion derivative of furazolidone appeared to be provided essentially by the microsomal cytochrome P450 reductase. This was confirmed through studies of the NADPH-dependent radical formation by microsomes. Differentiated Caco-2 cells, an established enterocyte model, showed only modestly increased radical formation and the same enzyme-specificity pattern as undifferentiated cells. Consistently, only a small increase in P450 reductase activity was found in differentiated cells, in contrast to the 10-fold increase seen in typical differentiation marker enzymes. With the electron spin resonance method that we describe, it is possible to distinguish between sites of bioactivation of redox active drugs in intact cells.

Animals↗
PubMed1996

In vivo uptake of Cu, Zn superoxide dismutase. Morphological evidence for preferential endocytosis and accumulation by sinusoidal liver cells.

Bovine Cu, Zn superoxide dismutase (SOD), conjugated to colloidal gold, was intravenously administered to rats and its distribution studied by electron microscopy. Liver was the preferential site of accumulation of gold-labelled SOD. Among liver cells types, Kupffer and endothelial cells showed the presence of the protein earlier than hepatocytes. Uptake by kidney showed slower kinetics than liver. No uptake by heart could be detected. The gold-labelled SOD was localized inside coated pits, coated vesicles and other non-coated endocytic compartments. Absence of binding by BSA-gold complexes and competition between free SOD and the gold-labelled one demonstrated the specificity of the uptake process. Our morphological evidences suggest that in vivo internalization of SOD occurs most likely through receptor-mediated endocytosis.

Animals↗
PubMed1996

[Youthful sudden cardiac death and the Kawasaki syndrome. An anatomopathological case report].

In 1967 Kawasaki studied 50 cases with the same features as mucocutaneous lymph node syndrome, further reported throughout Japan with the eponym of Kawasaki's disease. It is frequent in Japan and in USA, whereas in Europe it is sporadic and often misinterpreted. It presents as an acute fever, attended by irritation of the skin and oral mucosa, with swelling of cervical lymph nodes, easily misdiagnosed as scarlet fever, Stevens Johnson syndrome, or infantile exanthema or allergy. After the acute phase, Kawasaki's disease becomes chronic and sudden death is possible even if many years have elapsed. In the chronic phase, coronaritis, coronary aneurysms, marked stenosis and/or occlusive thrombosis are often present. Cardiac Lesions were classified from stage I to IV according to the duration of illness at death. The present work deals with the case of a 17 year old man, dying from undiagnosed coronary artery chronic Kawasaki disease. The patient had been hospitalized for Wolff-Parkinson-white syndrome; ten months after discharge he died suddenly, while performing gymnastics at school. Occluding thrombosis of cylindrical aneurysm of both coronary arteries, from undiagnosed Kawasaki arteritis, was found and the young boy succumbed to hyperacute infarction. The heart was fixed in buffered formalin 10% and embedded in paraffin. Histological examination of the cardiac conduction system has been carried out on serial sections, with the technique usually adopted by one of the present authors (L. Rossi). Hema-toxylin-eosin (H-E) and trichromic (Hei-denhein-azan) stainings have routinely employed.

Adolescent↗
PubMed1996

Anatomic thoracoscopic lobectomy (ATL) without minithoracotomy: preliminary experience.

UNLABELLED: The purpose of this review is to outline our experience with a completely thoracoscopic approach to major pulmonary resection (lobectomy). There were 23 patients in this study selected by the usual criteria of resectability. The preoperative workup included chest x-ray, pulmonary function studies, computed tomography (CT) of the chest and abdomen, bronchoscopy, mediastinoscopy, and brain and bone scans in the majority of patients. ATL was attempted in 23 patients. In four patients the procedure was converted to the "open" approach for the following reasons: inability to identify the location of the primary lesion (two patients), obscurative bleeding (one patient), and inability to diagnose the pathology (one patient). The underlying pathology of the ATL group was as follows: bronchiolitis obliterans-organizing pneumonia = 1, granuloma = 2, non-small cell lung cancer = 14, solitary colonic metastases = 2. The breakdown by site of the 19 ATL resections is as follows: right upper lobe = 5, right middle lobe = 1, right lower lobe = 1, right upper and right middle lobes = 1, left upper lobe = 6, left lower lobe = 5. Group A patients (n = 11) were those who had no postoperative complications. Length of stay was short, ranging from 4 to 8 days, median 5 days. Group B patients (n = 8) had complications (prolonged air leak = 4, supplemental postoperative oxygen requirement = 3, pain control = 1) and stayed longer (range 10-21 days, median 13). There were no deaths, no blood transfusions, no chest tube reinsertions and no reoperations. The most significant complication in the ATL group was prolonged air leak in one patient (21 days). CONCLUSIONS: (a) ATL without minithoracotomy is feasible; (b) ATL has potential benefits in terms of reduction of pain and hospital stay; (c) ATL had better cosmetic and functional results.

Adult↗