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R Nano

Publications and source records attributed to R Nano.

At least 73 records · Page 4Linked to original sources
PubMed1981

Propidium iodide as a probe for the study of chromatin thermal denaturation in situ.

The possibility of using propidium iodide, a phenanthridinic fluorochrome specific for double-stranded nucleic acids, for the study of chromatin thermal denaturation in situ has been examined. Smears of lymphocytes and hepatocyte nuclei from 15-day-old rats were fixed in acetic acid--ethanol (1:3 v/v), treated with RNAse and submitted to different protein extraction procedures, namely, incubation with pepsin, trypsin and sodium chloride. Denaturation experiments were performed in Sörensen buffer at pH 7.4 containing 10% formamide at temperatures between 27 and 95 degrees C. The samples were stained with propidium iodide and mounted in buffer or glycerol. Measurements were performed with a microfluorometer at a wavelength of 446 nm. The results indicate a higher thermostability of lymphocytes as compared to hepatocytes. The denaturation pattern suggests a certain organization complexity of chromatin, better emphasized by the derivative curves which show the presence of at least three fractions with different melting points. After protein extraction, the denaturation curves exhibit a somewhat simplified pattern, with the disappearance of the most stable peak in the derivative curves. The samples mounted in glycerine exhibit a better stability of staining with time, and an increased quantum efficiency of the fluorochrome with regard to those mounted in buffer. These data confirm the importance of protein--DNA interactions in the organization of chromatin and point to some differences, depending on the cell type and on functional activity.

Animals↗
PubMed1981

N-acetyl-beta-glucosaminidase activity in normal and acute leukemia blood cells.

N-acetyl-beta-glucosaminidase activity was studied by cytochemical means in blood cells of 20 normal controls and in blast cells of 21 cases of acute leukemia. All normal granulocytes and monocytes showed finely granular positivity, whereas the lymphocytes were unreactive or showed various granular positivity patterns. The intensity of enzymic activity was not significantly different in the various subtypes of acute leukemia. However the lymphoblasts showed a characteristic positivity pattern with activity being present both in coarse and fine granules located at one pole of the cell. This allowed them to be distinguished from the other leukemic blasts showing fine granules scattered throughout cytoplasm.

Acetylglucosaminidase↗
PubMed1979

[Histochemical demonstration of tetrahydrofolate dehydrogenase in human bone marrow: apparent enzymatic induction after administration of folic acid antagonists].

Folate antagonists interfere to a varying extent with the histochemical demonstration of tetrahydrofolate dehydrogenase. Some aspects of this interaction are investigated in normal hemopoietic cells of patients following antitumor treatment with methotrexate. In this situation the histochemically detectable activity of tetrahydrofolate dehydrogenase exceeds the control levels (apparent enzymatic induction). A protection of the enzyme-metabolite complex from degradation and diffusion might be effective for the changes in reaction intensity.

Bone Marrow↗
PubMed1978

Tetrahydrofolate dehydrogenase in blood cells and in hematopoietic organs of different vertebrate species.

Some general aspects in cytochemical demonstration of the tetrahydrofolate dehydrogenase, concerning the final reaction product, are studied. Steady and variable factors are detected in a comparative study of Vertebrate hemopoiesis: the enzyme exhibits peculiar features in different cell types. The reactivity progressively decrease in the erythropoietic series, in concomitance with hemoglobin synthesis. Conversely an increase in the intensity of reaction is found in the granulocytopoietic series; the correspondence of positive material with the specific (eosinophil and heterophil) granulations can be discussed. The thrombocytopoietic series is also labelled by this reaction.

Animals↗
PubMedDate not supplied

Boron-loaded liposomes in the treatment of hepatic metastases: preliminary investigation by autoradiography analysis.

Boronophenylalanine (BPA)-loaded conventional and stabilized liposomes were prepared by the reversed phase evaporation method to treat liver metastases by boron neutron capture therapy. Conventional vesicles were composed of phosphatidylcholine and cholesterol, molar ratio 1:1. To obtain stealth liposomes, GM1 or PEG were included in the lipidic bilayer at a concentration of 6.67 or 5 mol%, respectively. Large unilamellar vesicles were formulated encapsulating BPA in the liposome aqueous compartment as a complex with fructose; BPA free base also was embedded into the lipidic bilayer. In vivo experiments were carried out after intravenous injection of liposome suspensions in BD-IX strain rats in which liver metastases had been induced. Alpha particle spectroscopy associated with histological analysis was performed to visualize boron spatial distribution in liver. Simultaneously, tissue boron concentrations were determined using inductively coupled plasma-mass spectroscopy. Results showed that PEG-modified liposomes accumulated boron in therapeutic concentrations (> 30 micrograms boron/g tissue) in metastatic tissue. The PEG-liposomes could be further explored in enhancing boron delivery to tumor cells.

Animals↗
PubMedDate not supplied

Lessons from in vitro perifusion of pancreatic islets isolated from 80 human pancreases.

We report the average insulin response to acute glucose measured by in vitro perifusion of pancreatic islets isolated from 80 consecutive human organs. Different perifusion parameters were considered [basal release, stimulation index (SI), time to peak, incremental area under the curve delta-AUC alpha)], and the correlation among them was determined. SI positively correlated with delta-AUC alpha (p < 0.001, r = 0.80) while negatively with time to peak (p < 0.05, r = -0.23). We also evaluated several variables of the isolation procedure that might affect responsiveness to glucose by human islets. Sex and age of pancreas donors, cold ischemia time, duration of the digestion, collagenase concentration, and lot characteristics (collagenase, trypsin, clostripain, and proteases activity), and final islet yield were considered. Multivariate regression analysis showed only an independent association between SI and the concentration of collagenase (p = 0.01).

Adolescent↗
PubMedDate not supplied

Identification of genetic markers of the glial tumor by means of differential display technique.

The Differential Display Reverse Transcriptase (DDRT) technique was adopted to isolate genetic markers specific for the two main grades of the Glial tumor, the Astrocytoma and the Glioblastoma. A total of 16 brain biopsies (4 Astrocytoma and 12 Glioblastoma) were analysed. The technique was modified in order to reduce the false-positive ratio by means of more stringent amplification conditions. Electrophoretic patterns with previously selected arbitrarily primers revealed differences between the grades, four of them were investigated through sequencing. These sequences did not show significant nucleotide and aminoacid similarity to any known sequences in the DataBase. Sensitivity of the method was documented by the evidence that only one of the selected markers was an artefact, while the others represented genetic markers of the human Glial neoplasm.

Astrocytoma↗
PubMedDate not supplied

Interleukin-2 induces the growth of human glioblastoma cells in culture.

The ability of the T cell growth factor interleukin-2 (IL-2) to support the proliferation of human glioblastoma cells in short-term cultures was evaluated. A morphological, cytochemical and immunocytochemical analysis was carried out at different times of treatment. In the presence of IL-2 growth of tumor cells was observed. On the contrary, in the absence of IL-2 only few colonies derived from tumor fragments were obtained and these were so after a long time. The immunocytochemical study revealed that IL-2 induces the expression of the IL-2 receptor on human glioblastoma cells. In the presence of IL-2 proliferation of infiltrating lymphoid cells inside the tumor fragments was also observed. Morphological and cytochemical analysis of these cells revealed positivity for acid phosphatase (AP), dihydrofolate reductase (DHFR), dipeptydilaminopeptidase (DAP IV) and negativity for serine esterase. These data are in agreement with our previous study on activated lymphoid subsets. On the other hand, an absence of infiltrating lymphocytes was observed in cultures without IL-2. These results indicate that local treatment of human glioblastoma using IL-2 might produce tumor cell proliferation.

Brain Neoplasms↗
PubMedDate not supplied

Evaluation of a possible styrene-induced damage to the haematopoietic tissues in the rat.

The aim of this study was to determine a possible risk of malignancies in the haematopoietic tissues of rats treated with styrene, either by injection or by inhalation. Two experiments were carried out: in the first (acute treatment), 12 male rats were treated intraperitoneally with different doses of styrene (40 mg/Kg/2 ml/die and 400 mg/Kg/2 ml/die) for 3 consecutive days. A control group (6 rats) was administered corn oil 2 ml/kg/die for the same period of time. In the second experiment (chronic treatment), 12 male rats were exposed to styrene inhalation (300 ppm/6 hour day/5 days a week for 2 weeks) for 3 weeks and sacrificed at the end of the experiment or after 3 weeks. The rats treated with the highest doses of styrene by injection (400 mg/kg, acute treatment) showed a hyperactivity of the erythropoietic series while the granulocytopoietic series was at the normal value. The rats exposed to 300 ppm styrene vapour (chronic treatment) showed a statistically significant increase in erythropoietic cells (basophilic, polychromatophilic and orthochromatic erythroblasts). A temporary block of immature cells of the granulocytopoietic series was also evident. These results indicate an alteration of the erythropoietic series independently of method of administration. However, these findings do not show a possible risk of preleukemic or leukemic disorders in rats exposed or treated with styrene.

Administration, Inhalation↗
PubMedDate not supplied

HLA class I molecules expression: evaluation of different immunocytochemical methods in malignant lesions.

It is generally accepted that human and experimental tumour cells can lose Major Histocompatibility Complex (MHC) class I molecules and this represents the major mechanism of tumour escape from T-cell immune responses. Nevertheless testing of HL4 class I antigen expression in malignant lesions is not routinely used to evaluate the immunological conditions of the patients because of the pathologists' reluctance to utilise frozen tissue sections in immunocytochemisty. We analysed the expressions of HLA class I molecule and beta2-microglobulin in normal and neoplastic tissues, comparing different samples and methods. The expression of HLA receptors was studied in 7 brain tumours, 10 colon adenocarcinoma and 2 breast carcinoma by immunocytochemical technique. 4 normal tissues and peripheral blood mononucleated cells were analysed as positive control. The peroxidase staining method was performed on fresh imprints, frozen sections, formalin- fixed tissues and fine-needle aspirates. The results indicated that the best and simplest conditions for the detection of HLA molecules were obtained using fresh imprints and fine-needle aspirates.

Adenocarcinoma↗
PubMedDate not supplied

Minichromosome maintenance protein 7: a reliable tool for glioblastoma proliferation index.

At present there is increasing evidence concerning the value of minichromosome maintenance (MCM) protein expression as a novel indicator of proliferation. In the present study, 15 glioblastoma samples, classified according to WHO, were analysed to evaluate the expression of the principal proliferation markers. The samples examined were subdivided into 2 cytological subsets, small cell (SC) or multiforme cell (MC) glioblastoma, according to the predominant cell type defined in individual specimens. MCM7 detected more cells in the cycle than Ki67 and PCNA and all cases of SC glioblastoma, the most aggressive subset, displayed a significant increase of MCM7-stained nuclei versus those stained with Ki67. These results suggest that the cell cycle-associated proteins MCM are not only useful markers of proliferation, but also valid aids for diagnosis in cerebral glioblastoma.

Adult↗
PubMedDate not supplied

Histochemical study of cardiac mast cells degranulation and collagen deposition: interaction with the cathecolaminergic system in the rat.

Although their role in the cardiovascular system is still largely unknown, mast cells are present in the myocardium of both experimental animals and humans. Interestingly, cathecolaminergic nerve fibres and mast cells are often described in close morphological and functional interactions in various organs. In the present study we investigated the effects of chronic interference with beta-adrenergic receptors (via either sympathectomy or beta-blockade) on cardiac mast cell morphology/activation and on interstitial collagen deposition. In rats subjected to chemical sympathectomizy with the neurotoxin 6-hydroxydopamine (6-OHDA) we observed a significant increase of mast cell density, and in particular of degranulating mast cells, suggesting a close relationship between the cardiac catecholaminergic system and mast cell activation. In parallel, chronic 6-OHDA treatment was associated with increased collagen deposition. The influence of the beta-adrenergic receptor component was investigated in rats subjected to chronic propranolol administration, that caused a further significant increase in mast cell activation associated with a lower extent of collagen deposition when compared to chemical sympathectomy. These data are the first demonstration of a close relationship between rat cardiac mast cell activation and the catecholaminergic system, with a complex interplay with cardiac collagen deposition. Specifically, abrogation of the cardiac sympathetic efferent drive by chemical sympathectomy causes mast cell activation and interstitial fibrosis, possibly due to the local effects of the neurotoxin 6-hydroxydopamine. In contrast, beta-adrenergic blockade is associated with enhanced mast cell degranulation and a lower extent of collagen deposition in the normal myocardium. In conclusion, cardiac mast cell activation is influenced by beta-adrenergic influences.

Animals↗