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Biomedical subjects

R Pagani

Publications and source records attributed to R Pagani.

At least 19 recordsLinked to original sources
PubMed2004

In vitro biocompatibility assessment of poly(epsilon-caprolactone) films using L929 mouse fibroblasts.

Biodegradable and biocompatible materials are the basis for tissue engineering. As an initial step for developing vascular grafts, the in vitro biocompatibility of poly(epsilon-caprolactone) (PCL), recently suggested for several clinical applications, was evaluated in this study using L929 mouse fibroblasts. Different cellular aspects were analyzed in order to know the cell viability during cell culture on PCL films: adhesion, proliferation, morphology, LDH release and mitochondrial function. Since topography and other surface characteristics of materials play an essential part in cell adhesion, PCL membranes with either smooth or rough surface were prepared, characterized and used to carry out cell cultures. During short culture times, PCL produced a significant stimulation of mitochondrial activity evaluated by reduction of the MTT reagent. The results provide evidences of good adhesion, growth, viability, morphology and mitochondrial activity of cells on PCL films. Therefore, it can be concluded that PCL is a suitable and biocompatible material as a scaffold for vascular graft development.

Animals↗
PubMed2004

Differential expression of alpha 1 and beta subunits of voltage dependent Ca2+ channel at the neuromuscular junction of normal and P/Q Ca2+ channel knockout mouse.

Voltage-dependent calcium channels (VDCC) have a key role in neuronal function transforming the voltage signals into intracellular calcium signals. They are composed of the pore-forming alpha(1) and the regulatory alpha(2)delta, gamma and beta subunits. Molecular and functional studies have revealed which alpha(1) subunit gene product is the molecular constituent of each class of native calcium channel (L, N, P/Q, R and T type). Electrophysiological and immunocytochemical studies have suggested that at adult mouse motor nerve terminal (MNT) only P/Q type channels, formed by alpha(1A) subunit, mediate evoked transmitter release. The generation of alpha(1A)-null mutant mice offers an opportunity to study the expression and localization of calcium channels at a synapse with complete loss of P/Q calcium channel. We have investigated the expression and localization of VDCCs alpha(1) and beta subunits at the wild type (WT) and knockout (KO) mouse neuromuscular junction (NMJ) using fluorescence immunocytochemistry. The alpha(1A) subunit was observed only at WT NMJ and was absent at denervated muscles and at KO NMJ. The subunits alpha(1B), alpha(1D) and alpha(1E) were also present at WT NMJ and they were over- expressed at KO NMJ suggesting a compensatory expression due to the lack of the alpha(1A). On the other hand, the beta(1b), beta(2a) and beta(4) were present at the same levels in both genotypes. The presence of other types of VDCC at WT NMJ indicate that they may play other roles in the signaling process which have not been elucidated and also shows that other types of VDCC are able to substitute the alpha(1A) subunit, P/Q channel under certain pathological conditions.

Animals↗
PubMed2004

Dual task effects of walking when talking in Alzheimer's disease.

Previous studies with Alzheimer Disease (AD) patients have suggested that speed and accuracy in walking can be dramatically affected by a simultaneous secondary cognitive task, such as holding a conversation. Two experiments examined the impact on AD patients and age matched elderly controls of cognitive demands while walking. In Experiment 1 walking for AD patients was more affected than it was for the normal elderly by a concurrent cognitive demand. Experiment 2 demonstrated that both groups were equally impaired under dual task conditions when the demands of the cognitive tasks were adjusted for individual levels of ability. We conclude that walking may draw on general executive resources, that walking relies more heavily on these executive resources in the elderly, and on a damaged executive system for AD patients.

Aged↗
PubMed2003

Nifedipine-mediated mobilization of intracellular calcium stores increases spontaneous neurotransmitter release at neonatal rat motor nerve terminals.

The modulation of spontaneous release of acetylcholine by specific Ca2+ channel blockers was studied at neonatal rat neuromuscular junction. During early postnatal periods (0-4 days), blockers of N- and P/Q-type Ca2+ channels did not affect miniature endplate potential (MEPP) frequency. Unexpectedly, treatment with the L-type Ca2+ channel antagonist nifedipine, although not when treated with isradipine, nitrendipine, or calciseptine, resulted in strong increase in MEPP frequency. The potentiation effect of nifedipine was dose-dependent with a 56-fold maximum effect with 15 microM. The effect decreased during the first two postnatal weeks and disappeared by the third. The effect of nifedipine was not dependent on extracellular Ca2+ and was not altered by the presence of other Ca2+ channel blockers. In contrast, it was abolished by depleting intracellular Ca2+ stores with 2 microM thapsigargin and was partially inhibited by 10 microM ryanodine. In conclusion, we report a new ryanodine receptor-mediated effect of nifedipine on neonatal neuromuscular junction that may indicate the developmental expression of a specific receptor channel that interacts with intracellular Ca2+ stores. This effect of nifedipine should also be considered when using this drug as either a therapeutic or a research tool.

Age Factors↗
PubMed2003

Alterations induced on cytoskeleton by Escherichia coli endotoxin in different types of rat liver cell cultures.

Endotoxins (lipopolysaccharide, LPS) from Gram-negative bacteria are considered as the agents responsible for the induction of endotoxic shock, producing severe cellular metabolic dishomeostasis. Cytotoxic lesions, as well as functional and metabolic disturbances, occur mainly in the liver, which is one of the target organs and exerts an LPS clearance function. In an attempt to approach the molecular basis of endotoxic shock, and to propose an experimental model, we have focused this study on cytoskeleton (microtubules and microfilaments) alterations induced by different doses of endotoxin in different target liver cells. Microfilaments and microtubules were studied by immunofluorescence and different microscopy techniques (optic fluorescence microscopy and confocal laser scanning microscopy) in order to improve the cytoskeleton study resolution. Parenchymal and sinusoidal cell morphology, severely damaged by the LPS action, is related to a disturbance on the cytoskeletal organisation, even more evident in a particular proliferating rat liver cell culture. The most relevant changes are seen in the microtubule patterns in all liver cells tested, which could be related, depending on cell type, either to a direct LPS action or to [Ca+2]i dishomeostasis as well as free radical and cytokine (IL-1beta and TNF-alpha) production. Due to their features, proliferating rat liver cell cultures are used as a sensitive cell model to understand the effect of LPS on cytoskeleton organisation.

Animals↗
PubMed2002

[Epithelial leiomyosarcoma of gingiva: a case report and review of literature].

Epithelioid leiomyosarcoma (EL) is a rare malignant tumor of mesenchymal origin. The Authors review the literature and report a case of gingival epithelioid leiomyosarcoma in a 40-year-old patient. In this case the leiomyosarcoma was located in the lower front dental group and invaded the symphysis menti. A segmentary mandibolectomy was performed with reconstruction using a non-revascularized autologous iliac bone graft. The differential diagnosis of primary EL is quite complex and it is grouped with other sarcomas, sarcomatoid carcinoma, myoepithelioma, amelanotic melanoma and metastases from gastrointestinal EL. Anatomopathological examination and immunohistochemical study enabled a definitive diagnosis of primary EL of gingiva. The follow-up calls for clinical-radiological check-ups every three months for the first year and every six months thereafter. One year after surgery there were no signs of recurrence.

Adult↗
PubMed2001

Inhibition and regulation of rat liver L-threonine dehydrogenase by different fatty acids and their derivatives.

Rat liver L-threonine dehydrogenase is a mitochondrial enzyme which transforms L-threonine either into aminoacetone or into acetyl-CoA. We show that it is inhibited by several fatty acids and their derivatives: short chain fatty acids, L-2-hydroxybutyrate and D-3-hydroxybutyrate, long chain fatty acids, such as lauric acid, myristic acid, palmitic and stearic acids, bicarboxylic acids such as malonic acid and its derivatives methyl- and hydroxymalonic acids. The inhibition occurs at low and physiological concentrations of such compounds, which are normally present and metabolized in mitochondria. It presumably plays a role in the physiology of acetyl-CoA-dependent formation of fatty acids and ketobodies, in L-threonine-dependent gluconeogenesis, and in the regulation of L-threonine metabolism by L-threonine dehydrogenase and L-threonine deaminase.

3-Hydroxybutyric Acid↗
PubMed2001

Determining the binding capability of the mouse major urinary proteins using 2-naphthol as a fluorescent probe.

The mouse major urinary proteins (MUPs) are an ensemble of isoforms secreted by adult male mice and involved in sexual olfactory communication. MUPs belong to the lipocalin superfamily, whose conserved structure is a beta-barrel made of eight antiparallel beta-strands forming a hydrophobic pocket that accommodates small organic molecules. A detailed knowledge of the molecular mechanism associated to the binding of those molecules can guide protein engineering to devise mutated proteins where the ligand specificity, binding affinity, and release rate can be modulated. Proteins with such peculiar properties may have interesting biotechnological applications for pest control, as well as in food and cosmetic industries. In this work, we demonstrate that the fluorescent molecule 2-naphthol binds to the natural ligand's binding site of MUPs with high affinity. In addition, we show that 2-naphthol binds to MUPs in its protonated form, that its fluorescence is blue-shifted, and the quantum yield is increased, thus confirming the high hydrophobicity of the protein pocket and the absence of proton acceptors inside the binding site. At large the results presented, besides demonstrating that the use of 2-naphthol provides a convenient and quick method for testing MUPs binding activity and to ascertain the quality of the protein preparation, suggest that MUPs can represent an interesting system for studying the photophysical characteristics of fluorescent molecules in a highly hydrophobic environment.

Animals↗
PubMed2001

Blood chemistry of rats pretreated with Mucuna pruriens seed aqueous extract MP101UJ after Echis carinatus venom challenge.

The effect of a lethal Echis carinatus venom on serum enzyme levels and blood plasma coagulation parameters in rats pretreated with Mucuna pruriens seed aqueous extract MP101UJ (21 mg/kg body wt) 24 h and 3 wk before i.p venom injection (0.50 mg/kg rat) and rats injected with venom alone (0.50 mg/kg body wt) was investigated. The enzyme levels and coagulation parameter levels were measured 4 h after venom administration. The results showed that the increased enzymes lactate dehydrogenase (LDH), glutamic pyruvic transaminase (SGPT), creatinine kinase (CK) and changed coagulation parameters D-Dimer and Quick levels due to the venom effect were inhibited by M. pruriens seed aqueous extract MP101UJ in pretreated rats. Rats pretreated with a single dose (21 mg/kg and multiple doses 21 mg/kg rat) of extract MP101UJ maintained the normal enzyme levels and showed an anticoagulant effect as evidenced by the high PTT level which was also observed in venom treated animals. D-Dimer and Quick values were normal. However, the extract MP101UJ appeared to significantly inhibit the lethal venom induced myotoxic, cytotoxic and coagulation activities in experimental animals.

Animals↗
PubMed2001

Effects of Mucuna pruriens extract on activation of prothrombin by Echis carinatus venom.

Mucuna pruriens (L.) DC has long been used as a medicinal plant by traditional healers. The validity of the claims made for this plant has also been tested scientifically. Some of its properties are probably linked to high concentrations of dopa since it is useful in the treatment of Parkinson's disease. The antisnake properties of an extract of Mucuna pruriens' seeds (MP101UJ) in vivo were recently demonstrated and one is now investigating its biochemical mechanism. Echis carinatus venom (EV) contains a mixture of proteins that affect the coagulative cascade, causing severe bleeding and haemorrhage. Here the effect of an extract of MP101UJ in prothrombin activation by EV in vitro by clotting and chromogenic assay is studied. An increase in procoagulant activity was found. This could explain the protective effect in vivo.

Animals↗
PubMed2001

The staircase technique for treatment of cancer of the lower lip: a report of 36 cases.

PURPOSE: This article reports the authors' experience with treatment of lower lip cancer using the staircase technique. PATIENTS AND METHODS: Thirty-six patients with stage T1 or T2 cancers of the lower lip were treated. RESULTS: No recurrences were observed during a 6- to 32-month follow-up. All patients showed excellent aesthetic results and no microstomia. CONCLUSIONS: The staircase technique can be used to close defects of up to two thirds of the lower lip. Two bilateral symmetric flaps are used for median defects; 2 bilateral asymmetric flaps are used for paramedian defects greater than 20 mm; and only 1 contralateral flap is required for paramedian defects up to 20 mm.

Aged↗
PubMed2001

Melting temperature analysis as quantitative method for detection of point mutations.

Different methods have been devised to detect point mutations. Some are very sensitive, detecting mutations even in a background of normal tissue, but none provide information about the percentage of cells with mutant DNA. Here we describe an easy, fast and reliable method, melting temperature analysis, which not only detects point mutations but also provides quantitative information on the percentage of cells with mutant DNA. By this method we detected a G-A transition in codon 12 of the K-ras gene in DNA of subjects with colorectal cancer. The K-ras mutation was found in 9/10 bowel cancers and 8/10 normal adjacent samples. It was also detected in 4/7 stool samples from the same patients. In colorectal cancers, the proportion of K-ras mutant cells was variable: in two the mutant/wild-type DNA ratio was 30/70, in three 50/50, and in four 70/30. Melting temperature analysis was sensitive for the detection of point mutations in bowel cancer and also in apparently normal tissue, providing quantitative information about the percentage of cells with mutant DNA.

Colorectal Neoplasms↗
PubMed2000

Fatty acid composition of phospholipids, triglycerides and cholesterol in serum of castrated and estradiol treated rats.

We have studied the levels of phospholipids, triglycerides, cholesterol esters, and their fatty acid composition in serum for normal, castrated and estradiol treated rats. The sex hormones did not greatly affect the levels of the various lipid fractions which did not undergo great significant variations, under the different treatments. More evident variations occurred in the percent composition of fatty acid and in the content of the various saturated (SAT), unsaturated (UNSAT), essential (EFA) and non essential fatty acids (NEFA). We studied the most important ratios: EFA/NEFA; UNS/SAT; 16:0/16:1; 18:0/18:1, 18:2/18:3; 18:2/20:4. 16:0/16:1; 18:0/18:1 represent the delta9 desaturase, one specific for palmitic, the other for stearic acid. 18:2/18:3 ratio is an index of the delta6 desaturase activity: 18:2/20:4 ratio of delta5 desaturase-elongase. Most changes were evident in triglycerides. We observed a different behaviour of the UNS/SAT and EFA/NEFA ratios in phospholipids and cholesterol esters, which may reflect either an effect of the sex hormones on the exchange of fatty acids between the same lipid fractions, or a redistribution of lipids among different tissues. Great variations were observed of the ratios 16:0/16:1; 18:0/18:1; 18:2/18:3; 18:2/20:4, which are ascribed a different effect of the sex hormones of delta9, delta6, delta5 desaturases.

Animals↗
PubMed1999

Synthesis of adenine and guanine nucleotides at the 'inosinic branch point' in lymphocytes of leukemia patients.

The synthesis of purine nucleotides has been studied in human peripheral blood lymphocytes from healthy subjects and patients affected by B-cell chronic lymphocytic leukemia (B-CLL). The rate of the synthesis was measured by following the incorporation of 14C-formate into the nucleotides of lymphocyte suspensions. The whole sequence AMP-->ADP-->ATP was found reduced in B-CLL lymphocytes; in the case of guanylates only the last step of the sequence GMP-->GDP-->GTP was significantly lower in the same cells. From the analysis of these results, combined with previous data, we conclude that purine metabolism undergoes an imbalancement during CLL, which is partially compensated, and point out the importance of studying concomitantly purine metabolism and nucleic acid synthesis in leukemia cells.

Adenine Nucleotides↗
PubMed1999

Comparative determination of purine compounds in carotid plaque by capillary zone electrophoresis and high-performance liquid chromatography.

Allantoin, uric acid (UA), hypoxanthine (Hx) and xanthine (X) were determined on carotid plaque by capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC). Comparison of the results showed that capillary zone electrophoresis may have similar or even superior analytical performance to HPLC, especially for the determination of allantoin in biological samples.

Aged↗
PubMed1999

Escherichia coli lipopolysaccharide effects on proliferating rat liver cells in culture: a morphological and functional study.

Liver cells have been implicated in playing an important role in the pathogenesis of endotoxic shock-associated liver injury. The present study was designed to investigate Escherichia coli 0111:B4 lipopolysaccharide (LPS) effects on proliferating rat liver cells in culture. Isolated cell system can rarely serve as models of complete organisms, but with using an in vitro test-model, endogenic factors (e.g. hormonal effects, nervous influences, blood activation, etc.) or experimental stress in laboratory animals can be eliminated as variables affecting hepatocellular responses. In the proposed in vitro model, using specially proliferating liver cells, morphological cell alterations were observed after 30 min and low doses endotoxin administration (10 micrograms/ml). LPS induced an extreme fragility and a diminished adhesion capacity on cells. Cell-to-cell contacts were also disturbed. The LPS treatment produced extreme heterogeneity in liver cell size, enlargement of nuclei, nuclear and cytoplasmic protrusions, and increased the number of large nucleoli and lipid droplets, also decreasing the angiotensin action on intracellular calcium levels. The effects observed after the LPS exposition can be related with an altered metabolism of the liver cells in culture due to a destabilization of plasma membrane, a transmembrane signalling alteration, and a mitochondrial damage. The specificity of cell response to endotoxic lipopolysaccharide suggests a multiple membrane damage inducing important metabolic disturbances.

Animals↗