PubMed Health⌕ Search

Biomedical subjects

R Biondi

Publications and source records attributed to R Biondi.

At least 19 recordsLinked to original sources
PubMed2003

Evaluation of telomerase in non-melanoma skin cancer.

Telomerase, a ribonucleoprotein, is capable of adding telomeric sequences (TTAGGG hexameric repeats) to the ends of chromosomes and, thereby, halting the erosion of chromosome at each cell division. Whereas most normal somatic cells contain minimal or no detectable telomerase activity, most immortal and tumour cells exhibit significant levels of telomerase activity and show no net loss of telomere length during proliferation. The evaluation of telomerase has been proposed for diagnostic and therapeutic purposes in human cancer. Skin cancer is the most common cancer in humans; the precise molecular events in skin carcinogenesis are numerous and complicated and not yet completely clarified. In this study, we evaluated telomerase in 35 basal cell carcinomas and in 14 squamous cell carcinomas in order to determine if activation of the telomerase enzyme was a pivotal step in the development of skin cancer and whether telomerase activity levels were different between the two histotypes. A higher enzymatic level was shown to be associated with squamous cell carcinomas, while low levels were mainly detected in the basal cell histotype (chi2 test; p=0.02). Telomerase complex activity is dependent on its catalytic subunit, telomerase reverse transcriptase hTERT. By reverse transcription-PCR, using primers within the reverse transcriptase domain of hTERT, we observed a significant correlation between hTERT expression and telomerase activity in our skin tumour samples (p=0.0003). We detected the presence of multiple, alternately spliced transcripts, corresponding to full-length messages as well as spliced messages with critical reverse transcriptase motifs deleted. A higher telomerase messenger level was shown to be associated with squamous cell carcinomas (chi2 test; p<0.0001), as for telomerase activity. Our results provide arguments supporting the role of telomerase in skin cancer and suggest RT-PCR of telomerase RNA as a tool easier and faster than TRAP assay to identify more aggressive malignancies among non-melanoma skin specimens.

Adult↗
PubMed2001

Detection of hydroxyl radicals by D-phenylalanine hydroxylation: a specific assay for hydroxyl radical generation in biological systems.

Hydroxylation of l-phenylalanine (Phe) by hydroxyl radical (*OH) yields 4-, 3-, and 2-hydroxyl-Phe (para-, meta-, and ortho-tyrosine, respectively). Phe derivative measurements have been employed to detect *OH formation in cells and tissues, however, the specificity of this assay is limited since Phe derivatives also arise from intracellular Phe hydroxylase. d-Phe, the d-type enantiomer, is not hydroxylated by Phe hydroxylase. We evaluate whether d-Phe reacts with *OH as well as l-Phe, providing a more reliable probe for *OH generation in biological systems. With *OH generated by a Fenton reaction or xanthine oxidase, d- and l-Phe equally gave rise to p, m, o-tyr and this could be prevented by *OH scavengers. Resting human neutrophils (PMNs) markedly converted l-Phe to p-tyr, through non-oxidant-mediated reactions, whereas d-Phe was unaffected. In contrast, when PMNs were stimulated in the presence of redox cycling iron the *OH formed resulted in more significant rise of p-tyr from d-Phe (9.4-fold) than l-Phe (3.6-fold) due to the significant background formation of p-tyr from l-Phe. Together, these data indicated that d- and l-Phe were equally hydroxylated by *OH. Using d-Phe instead of l-Phe can eliminate the formation of Phe derivatives from Phe hydroxylase and achieve more specific, sensitive measurement of *OH in biological systems.

Cell Survival↗
PubMed2001

Oxygen radical-mediated reduction in basal and agonist-evoked NO release in isolated rat heart.

Oxygen free radicals (OFR) play a primary role in ischemia-reperfusion-mediated vascular dysfunction and this is paralleled by a loss of endothelial nitric oxide synthase (eNOS) activity. The authors tested whether a direct exposure to OFR may affect vascular relaxation by altering nitric oxide (NO) release. Effects of electrolysis(EL)-generated OFR on basal and agonist-evoked NO release were monitored in isolated rat hearts by oxyhemoglobin assay. Electrolysis-induced changes were compared with those obtained after 30 min perfusion with NOS and cyclooxygenase (COX) inhibitors NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) and indomethacin (INDO, 1 m M). Electrolysis-generated hydroxyl radical (.OH) formed by.O2-and H2O2 via the Fenton reaction as revealed by Electron Paramagnetic Resonance (EPR). After EL, basal NO release declined by 60% and coronary perfusion pressure (CPP) increased by approximately 70%. L-NAME/INDO perfusion similarly lowered NO release (-63%) but increased CPP less than EL (56+/-3%P<0.03 v post-EL). In presence of excess substrates and cofactors eNOS activity was not affected by EL. Both acetylcholine (ACh; 1 microM) and bradykinin (BK; 10 n M) had minimal effect in reversing EL-induced vasoconstriction, whereas both partially reversed L -NAME/INDO-mediated constriction. Sodium nitroprusside (SNP, 1 microM) completely reversed L-NAME/INDO constriction and partly countered that after EL (-38+/-2.5, P<0.001). Acetylcholine-evoked NO release was nearly abolished by both treatments whereas BK still elicited partial NO release after eNOS/cyclooxygenase inhibition (P<0.001) but not after EL. In conclusion, OFR severely impair NO-mediated coronary vasorelaxation affecting both basal and agonist-evoked NO release but not eNOS activity. However, EL also significantly blunts NOS/COX-independent vasodilation suggesting alteration of other vasodilatative pathways.

Acetylcholine↗
PubMed2001

Beta-N-acetylhexosaminidase activity and isoenzyme profile in the kidney and urine of trained rats.

Lysosomes play an important role in the immune system functioning and are involved in different aspects of inflammatory reaction, repair processes and tissue damage at various levels. Among various effects, it is known that physical exercise influences the release of different lysosomal components. The aim of this study was to evaluate enzyme activity and isoenzymatic profile of beta-N-acetylhexosaminidase both in kidney and urine of normal and trained rats. Enzyme activity was measured by fluorimetric assay while beta-N-acetylhexosaminidase isoenzymes were separated using DEAE-cellulose chromatography. Hexosaminidase specific activity was significantly increased in urine of trained rats whereas there was no increase in the kidneys of trained rats. Indeed, no significant differences were observed in the isoenzyme profile of kidney and urine extracts from normal and trained rats. Our findings suggest the exercise-induced release of lysosomal enzymes is a functional effect and not due to disruption of lysosomal membranes.

Animals↗
PubMed2001

Plasma endothelin-1 and big endothelin-1 levels in superior and inferior vena cava during protracted antiorthostatic hypokinetic/hypodynamia in rats.

The plasma levels of endothelin-1 and big endothelin-1 were evaluated in blood of rats in the superior and inferior vena cava, in normal posture (synchronous controls), and after 12 days head-down suspension and 1 day recovery in normal posture. In synchronous controls, the mean plasma concentration of endothelin-1 in inferior vena cava or superior vena cava was almost the same (5.89+/-0.63 pmol/l and 5.67+/-0.64 pmol/l, respectively), whereas the mean plasma concentration of big endothelin-1 was higher (p<0.05) in superior vena cava compared to inferior vena cava (5.49+/-0.75 pmol/l and 1.39+/-0.15 pmol/l, respectively). In samples from superior vena cava of head-down suspended rats big endothelin-1 levels were significantly lower (p<0.05) up to day 9 of suspension, compared to non-suspended synchronous controls, whereas endothelin-1 values were higher (p<0.05). Big endothelin-1 concentration was higher (p<0.05) in inferior vena cava compared to non-suspended synchronous controls. The behaviour of endothelin-1 was more complex, endothelin-1 levels were lower (p<0.05) on day 1 of head-down suspension and higher (p<0.05) in samples taken on days 9 and 12. After 1 day recovery endothelin-1 and big endothelin-1 concentrations returned to normal in both superior vena cava and inferior vena cava. These data indicate that the endothelial system involvement for the two venous beds is different and suggest that local rather than systemic evaluation could better explain endothelial involvement and the contribution of different anatomic sites to the biosynthesis, conversion and clearance of the various involved molecules.

Animals↗
PubMed2000

Neutrophil peripheral count and human leukocyte elastase during chronic lithium carbonate therapy.

Plasma levels of human polymorphonuclear elastase (PMN-E) are considered a marker of granulocyte activation and can potentially complement the peripheral neutrophil count in laboratory and pathophysiological settings. Neutrophilic leukocytosis is a well known effect of lithium therapy, but there is no information about the concomitant behaviour of PMN-E in these patients. The aim of this study was to evaluate both polymorphonuclear leukocyte count and plasma PMN-E levels in depression patients undergoing chronic lithium therapy. Absolute and differential leukocyte count in venous peripheral blood was determined by an automated method, and PMN-E evaluated by enzyme immunoassay. 39 patients (11 males, 28 females; mean age 43. +/- 6.02) with depression disorders were studied, during lithium carbonate therapy. Neutrophilia (neutrophil count > 7.500x10(9) cells per liter) was found in 7 (18%) patients and an increase in plasma PMN-E levels (PMN-E > 56 microg per liter ) in 6 (15%). No correlations were found between neutrophil count, plasma concentration of PMN-E, plasma level of lithium and duration of therapy. The results show that in these patients, not only the PMN count but also elastase levels can exceed the normal range. The absence of correlation between these two parameters suggests that the state of PMN activation is not linked to their number in peripheral blood.

Adult↗
PubMed2000

The mechanism of phosphorylation of anti-HIV D4T by nucleoside diphosphate kinase.

The last step in the intracellular activation of antiviral nucleoside analogs is the addition of the third phosphate by nucleoside diphosphate (NDP) kinase resulting in the synthesis of the viral reverse transcriptase substrates. We have previously shown that dideoxynucleotide analogs and 3'-deoxy-3'-azidothymidine (AZT) as di- or triphosphate are poor substrates for NDP kinase. By use of protein fluorescence, we monitor the phosphotransfer between the enzyme and the nucleotide analog. Here, we have studied the reactivity of D4T (2',3'-dideoxy-2',3'-didehydrothymidine; stavudine) as di- (DP) or triphosphate (TP) at the pre-steady state. The catalytic efficiency of D4T-DP or -TP is increased by a factor of 10 compared with AZT-DP or -TP, respectively. We use an inactive mutant of NDP kinase to monitor the binding of a TP derivative, and show that the affinity for D4T-TP is in the same range as for the natural substrate deoxythymidine triphosphate, but is 30 times higher than for AZT-TP. Our results indicate that D4T should be efficiently phosphorylated after intracellular maturation of a prodrug into D4T-monophosphate.

Adenosine Triphosphate↗
PubMed1999

Comparison of ipratropium bromide 0.03% with beclomethasone dipropionate in the treatment of perennial rhinitis in children.

OBJECTIVE: To compare the safety and efficacy of ipratropium bromide 0.03% (IB) with beclomethasone dipropionate 0.042% (BDP) in the treatment of perennial rhinitis in children. METHODS: Thirty-three children with nonallergic perennial rhinitis (NAPR) and 113 with allergic perennial rhinitis (APR) were randomly assigned to either IB or BDP for 6 months in a single-blind, multicenter protocol in which the physician was blinded to treatment. At each visit, patients and physicians rated symptom control of rhinorrhea, nasal congestion, and sneezing. Patients also completed quality of life questionnaires at baseline and after 6 months of therapy. RESULTS: Both treatments showed a significant improvement in control of rhinorrhea, congestion, and sneezing compared with baseline over the 6 months of treatment (P < .05). Only for the control of sneezing was BDP consistently better than IB (P < .05). Among the patients given IB, 61% to 73% assessed the control of rhinorrhea as good or excellent on different study visit days, 43% to 60% similarly rated the control of nasal congestion, and 39% to 43% the control of sneezing. The results for BDP were 68% to 78% for the control of rhinorrhea, 55% to 72% for the control of nasal congestion, and 54% to 68% for the control of sneezing. Quality of life assessment documented that both drugs significantly reduced interference with daily activities and disturbance of mood due to rhinorrhea compared with baseline (P < .05). Both treatments were well tolerated with IB causing less nasal bleeding and irritation than BDP. CONCLUSIONS: Ipratropium bromide was safe and effective in controlling rhinorrhea and diminishing the interference by rhinorrhea in school attendance, concentration on school work, and sleep. Ipratropium bromide was as effective as BDP in the control of rhinorrhea and showed a relatively good effect on congestion. Patient and physician assessment favored BDP in the control of sneezing.

Adolescent↗
PubMed1999

Seizures in Chiari I malformation: a clinical and electroencephalographic study.

Seven subjects with Chiari I malformations and seizures (four males, three females; age range 11 years, 7 months to 36 years; mean, 22.28 +/- 7.58 years; median, 21) were identified in four different centers from among a group of 10 patients. Our aim was to analyze clinical and electroencephalographic characteristics of seizures in this etiologically homogeneous group of patients. Most of the seizures were of the complex partial type, and paroxysmal abnormalities were mainly localized over the frontal and temporal regions. The course of the epilepsy was rather benign, with complete control of seizures in four patients and an important reduction in frequency in the remaining three subjects. Other cortical alterations are not usually associated with the typical abnormalities of the posterior fossa in Chiari I malformation; thus, it is possible to hypothesize that cerebral microdysgenesis or, alternatively, a cerebellar dysfunction could underlie epileptogenesis in these patients.

Adolescent↗
PubMed1998

Endothelin-1 and NO2/NO3 circulating levels after short-term (1h) oxygen supplementation in patients with chronic respiratory failure during long-term oxygen treatment (LTOT).

The effect of acute oxygen administration on endothelin-1 (ET-1) and nitrates (NO.2/NO.3), the latter as stable end products of nitric oxide (NO), were evaluated in arterial and venous blood of chronic respiratory failure (CRF) patients underwent to a continuous long-term oxygen therapy (LTOT). After one hour of oxygen supplementation, ET-1 showed a marked and significant decrease more pronounced in venous blood whereas no statistical change in NO.2/NO.3 concentrations were observed in both arterial and venous blood. There are evidences for increased expression of ET-1 in several pulmonary diseases and for ET-1 plasma reduction in Adult Respiratory Distress Syndrome (ARDS) in patients which recovered. ET-1 is a potent human pulmonary vessel constrictor and may have other effects including plasma exudation, increased mucus secretion and a increased fibrinogenesis. Our data suggest that the improvement in air function, evaluated in part by the decreased release of inflammatory mediators and mainly by reduction in the pulmonary arterial resistance, may be a consequence of the decrease in ET-1 content in the lungs of CRF patients treated with LTOT.

Aged↗
PubMed1997

X-ray analysis of azido-thymidine diphosphate binding to nucleoside diphosphate kinase.

To be effective as antiviral agent, AZT (3'-azido-3'-deoxythymidine) must be converted to a triphosphate derivative by cellular kinases. The conversion is inefficient and, to understand why AZT diphosphate is a poor substrate of nucleoside diphosphate (NDP) kinase, we determined a 2.3-A x-ray structure of a complex with the N119A point mutant of Dictyostelium NDP kinase. It shows that the analog binds at the same site and, except for the sugar ring pucker which is different, binds in the same way as the natural substrate thymidine diphosphate. However, the azido group that replaces the 3'OH of the deoxyribose in AZT displaces a lysine side chain involved in catalysis. Moreover, it is unable to make an internal hydrogen bond to the oxygen bridging the beta- and gamma-phosphate, which plays an important part in phosphate transfer.

Animals↗
PubMed1997

Effect of antiorthostatic hypokinetic/hypodynamia on urinary endothelin-1 and N-acetyl-beta-D-glucosaminidase excretion in rats.

In an experimental model with rats in head-down suspension, plasma levels and urinary excretion of endothelin-1 (ET-1) and urinary excretion of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) were determined. Significant variations in time in the effective plasma ET-1 levels in the superior and inferior cava vessel blood of animals maintained for 6 days in hypogravity with respect to controls were observed. We not only found a transient increase in urinary NAG activity but also that the levels of U-ET-1 increased during head-down suspension. The simultaneous evaluation at urinary level of these two parameters could be an indication that there are different sites of renal parenchymal involvement or injury during antiorthostatic hypokinesis.

Acetylglucosaminidase↗
PubMed1997

Ipratropium nasal spray in children with perennial rhinitis.

OBJECTIVE: To compare the efficacy and safety of ipratropium nasal spray and placebo administered twice each day for 4 weeks in pediatric patients with perennial rhinitis who had rhinorrhea as a major complaint. METHODS: This was a multicenter, double-blind, parallel group study. Patients aged 6 to 18 years with symptoms of perennial nonallergic (PNAR) or perennial allergic rhinitis (PAR) were randomized to receive ipratropium (42 micrograms per nostril) or placebo nasal spray, double-blind, twice each day for 4 weeks. Efficacy was evaluated by nasal symptoms, especially anterior rhinorrhea, and quality of life. Previous caregivers for rhinitis and medications used in the past were also evaluated. RESULTS: A total of 202 patients were empanelled, 162 with PAR, 40 with PNAR; of these 151 with mild-severe rhinorrhea were evaluated for efficacy. Treatment with ipratropium reduced symptoms of rhinorrhea primarily in patients with PNAR. In patients with PAR this response was less pronounced, and was seen as a modest decrease in the severity of rhinorrhea noted in the first 2 weeks of treatment. Quality of life assessments confirmed that rhinorrhea was bothersome to these pediatric patients, and suggested that treatment with ipratropium nasal spray was associated with an improvement, especially in the patients with PNAR. There were few adverse events; these were similar in the two treatment groups. CONCLUSIONS: Ipratropium nasal spray 0.03% administered at a dose of 42 micrograms/nostril bid is a safe and effective new therapy for control of anterior rhinorrhea in pediatric patients with PNAR. Twice daily administration is adequate for patients with PNAR, but patients with PAR might benefit from more frequent administration (e.g., tid).

Administration, Inhalation↗
PubMed1997

[Rehabilitation of peripheral nerve lesions].

After reporting the pathophysiology of denervation the authors deal with the changes that affect nerves while going through reinnervation. A review of the drugs that may help healing and general care to be adopted in order to avoid sequential pathological phenomena related to paralysis are shown. Rehabilitative treatment is discussed, the Authors dwell upon rehabilitation of neurogenous bladder of patients with spina bifida and rehabilitation of patients with paralysis of brachial plexus. Facial paralysis has been discussed before dealing with benefits and complications of electrotherapy. The use of electromagnetotherapy and electromyography are shown with a rich photographic and bibliographic support.

Brachial Plexus↗
PubMed1996

Cellular phosphorylation of anti-HIV nucleosides. Role of nucleoside diphosphate kinase.

Nucleotide analogs are widely used in antiviral therapy and particularly against AIDS. Delivered to the cell as nucleosides, they are phosphorylated into their active triphospho derivative form by cellular kinases from the host. The last step in this series of phosphorylations is performed by nucleoside diphosphate (NDP) kinase, an enzyme that can use both purine or pyrimidine and oxy- or deoxynucleotides as substrates. Using pure recombinant human NDP kinase type B (product of the gene nm23-H2), we have characterized the kinetic parameters of several nucleotide analogs for this enzyme. Contrary to what is generally assumed, diphospho- and triphospho- derivatives of azidothymidine as well as of dideoxyadenosine and dideoxythymidine are very poor substrates for NDP kinase. The rate of phosphorylation of these analogs varies between 0.05% and 0.5%, as compared to the corresponding natural nucleotide, a result that is not due to the inability of the analogs to bind to the enzyme. Using the data from the high resolution crystal structure of NDP kinase, we provide an interpretation of these results based on the crucial role played by the 3'-OH moiety of the nucleotide in catalysis.

Animals↗
PubMed1995

Cardiovascular and organ responses and adaptation responses to hypogravity in an experimental animal model.

The head-down suspension (i.e. antiorthostatic hypokinesia) rat is used to simulate weightlessness. However, little is known about cardiovascular and organ adaptation responses which, over a long time, can become pathologically significant. The purpose of this study was therefore to evaluate regional changes in the hematology parameters. Endotheline-1 (ET-1) concentration and urinary excretion of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) (NAG) in an experimental antiorthostatic rat model. The data indicate significant variations in the plasma ET-1 level in time, in the superior and inferior cava vessel blood of animals maintained for 10 days in hypogravity with respect to controls. These changes do not seem to be due to hemoconcentration. The increase in urinary NAG was observed during the first 24h of experiment, indicating renal stress, probably due to adverse blood flow variations within the organ. We conclude that the plasma ET-1 level changes could be responsible, overall for the blood flow variations in the kidney and renal stress could be the consequence of extended antiorthostatic hypokinesia. The ET-1 behaviour and urinary NAG excretion in rats exposed to antiorthostatic hypokinetic hydynamia offer possibilities for understanding if these changes might be reversible or when they become pathological. This could give some relevant information about the effects of prolonged hypogravity during the space voyage.

Acetylglucosaminidase↗
PubMed1995

Local and systemic immune response to inactivated Candida albicans in mice.

To improve our understanding of the role natural-immunity cells play in regulating the immune response to Candida albicans (CA) we compared local versus systemic effects of intraperitoneal inoculations with inactivated CA cells in mice. Peritoneal exudate cells (PECs) and spleen cells (SCs) were recovered from CD2F1 mice after 5 intraperitoneal CA injections (2 x 10(7) cells/mouse on days -14, -10, -7, -3 and 0 (CA-5d) with respect to in vitro assays performed at 2 h, 24 h, 3 days and 5 days). Northern blot analysis revealed that 2 h after CA-5d, PECs expressed a high level of IL-2, IFN-gamma, IL-1 beta and a low level of IL-10 and TNF-alpha mRNAs, while IL-4 and IL-5 mRNAs were absent, suggesting the development of TH1 subset. At 24 h, while IL-2 mRNA remained high, IL-1 beta and IFN-gamma expression had decreased and IL-10 and TNF-alpha mRNAs were no longer detectable. Instead, in spleens of CA-treated mice, examined up to 5 days after CA-5d, only IL-2 and IL-1 beta mRNAs were detectable, but the expression level was similar to that of untreated control mice. CA-5d induced a high level of natural-killer (NK)/lymphokine-activated-killer (LAK) activity in the peritoneal cavity but did not affect spleen NK activity. After CA-5d, the proliferative response of PECs to mitogens and CA antigens was also different from that of SCs. Unfractionated PECs were unable to proliferate in response to concanavalin A (Con A), IL-2, CA cells and CA cell wall mannoprotein, but after removal of the nylon-wool-adherent fraction, the nonadherent peritoneal cells (Nad-PECs) showed a significant proliferative response to mitogens. After depletion of NK cells by anti-asialo-GM1 antibody plus complement, the proliferative response of Nad-PECs to Con A and CA increased further. Contrary to the PEC response, unfractionated SCs from the same animals responded very well to mitogens and CA antigens and the proliferative response was significantly higher compared to that of SC from control mice. In conclusion, these results cast some light on the mechanisms by which NK cells and macrophages regulated the development of the local specific response to CA: activated NK cells, by producing IFN-gamma, favor the development of TH1 subset, while suppressor macrophages keep proliferation of T lymphocytes under control because of the presence of highly activated NK cells.

Animals↗