Biomedical subjects

A Bianchini

Publications and source records attributed to A Bianchini.

At least 19 recordsLinked to original sources

PubMed2006

Overcoming the rayleigh criterion limit with optical vortices.

We experimentally and numerically tested the separability of two independent equally luminous monochromatic and white light sources at the diffraction limit, using optical vortices (OV). The diffraction pattern of one of the two sources crosses a fork hologram on its center generating the Laguerre-Gaussian (LG) transform of an Airy disk. The second source, crossing the fork hologram in positions different from the optical center, generates nonsymmetric LG patterns. We formulated a criterion, based on the asymmetric intensity distribution of the superposed LG patterns so created, to resolve the two sources at angular distances much below the Rayleigh criterion. Analogous experiments in white light allow angular resolutions which are still one order of magnitude below the Rayleigh criterion. The use of OVs might offer new applications for stellar separation in future space experiments.

Journal Article↗

PubMed2006

Importance of cholinesterase kinetic parameters in environmental monitoring using estuarine fish.

The aim of the present study was to determine the kinetic parameters and cholinesterase (ChE) activity in two teleost fish, the white mouth croaker Micropogonias furnieri (Scianidae) and the Madamango sea catfish Cathorops spixii (Ariidae), to verify their suitability as sentinel species of aquatic pollution by anticholinergic compounds. Individuals of each species were captured in one reference and one polluted site in the Southern Brazilian coast. Brain tissue was used as enzyme source. Inhibition kinetic parameters indicated that ChE from C. spixii collected at the reference site showed more affinity (Ka) for eserine that from those collected at the polluted site. The opposite was observed for the carbamylation constants (Kc). Thus, similar inhibition constants (Ki) were observed. M. furnieri brain showed an extremely low sensitivity to in vitro inhibition by eserine, indicating that it is not a suitable biomarker to be employed in environmental monitoring of anticholinergic compounds. Results from the present study also point to the need for considering kinetic analysis when cholinesterase activity is employed as a biomarker.

Animals↗

PubMed2006

Immune adaptive response induced by Bicotylophora trachinoti (Monogenea: Diclidophoridae) infestation in pompano Trachinotus marginatus (Perciformes: Carangidae).

Fish have developed protective strategies against monogeneans through immunological responses. In this study, immune adaptive response to parasites was analysed in the pompano Trachinotus marginatus infested by Bicotylophora trachinoti. Hosts were pre-treated with formalin and after 10 days assigned to one of the following experimental treatments: (1) fish infested with remaining eggs of B. trachinoti; (2) fish infested with remaining eggs of B. trachinoti and experimentally re-infested by exposure to T. marginatus heavily infested with B. trachinoti. Samples were collected at 0, 15, and 30 days. Gills were dissected to check the presence of B. trachinoti. Blood was collected for haematological and biochemical assays. Spleen and head-kidney were dissected for phagocytosis assay. The spleen-somatic index was also calculated. Re-infested fish showed a faster and higher parasite infestation than infested ones. The parasite mean abundance at 15 days was 24.86+/-13.32 and 11.67+/-8.57 for re-infested and infested fish, respectively. In both groups, hosts showed an immune adaptive response to parasite infestation that was marked by an increased number of leukocytes. Also, phagocytosis (%) in spleen and head-kidney cells was stimulated after parasite infestation (92.50+/-3.73 and 66.00+/-9.54, respectively), becoming later depressed (77.39+/-6.69 and 53.23+/-9.14, respectively). These results support the hypothesis that monogenean infestation induces a biphasic response of the non-specific defence mechanisms in the pompano T. marginatus. This response is marked by an initial stimulation followed by a later depression of the non-specific defence mechanisms.

Animals↗

PubMed2005

Antioxidant responses after microcystin exposure in gills of an estuarine crab species pre-treated with vitamin E.

Microcystins are hepatotoxins suspected to generate oxidative stress. This mechanism was evaluated in gills of the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura). Adult male crabs were fed ground beef with or without vitamin E (600 mg/kg). Microcystin (1.21 microg/kg) was daily administered through forced ingestion, for 7 days. After exposure, catalase activity was reduced in posterior gills of crabs supplemented with vitamin E. A lower increment in glutathione S-transferase activity (GST) was observed in organisms pretreated with vitamin E and then exposed to microcystin with respect to those exposed to the toxin but not pretreated with the vitamin. Pretreatment with vitamin E also increased nonproteic sulfhyrdil groups and this effect was not observed after microcystin exposure. The fact that supplementation with antioxidants such as vitamin E modulates GST activity indicates the direct or indirect involvement of microcystin in oxidative stress generation.

Animals↗

PubMed2005

Antioxidant responses and oxidative stress after microcystin exposure in the hepatopancreas of an estuarine crab species.

Antioxidant responses and oxidative stress were evaluated in the hepatopancreas of the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) after oral microcystin administration. Responses were evaluated through antioxidant enzyme activities (catalase-(CAT), superoxide dismutase, glutathione-S-transferase- (GST)). Nonproteic sulfhydril (NP-SH) groups, oxygen consumption, lipid peroxides (LPO), and oxidized proteins were also measured. Microcystin administration increased the oxygen consumption. GST activity and NP-SH concentration showed transient increases and CAT activity showed a peak and then a reduction. Oxidative damage was evidenced with regard to LPO content and suggested by the inhibition of CAT activity at the end of the experiment, indicating that the antioxidant response induced by the toxin was insufficient. A lowering in the number of hepatopancreatic B cells should be related to microcystin elimination.

Animals↗

PubMed2004

Oxidative stress responses in two populations of Laeonereis acuta (Polychaeta, Nereididae) after acute and chronic exposure to copper.

Acute (4 days) and chronic (14 days) effects of copper were evaluated on the antioxidant defenses of Laeonereis acuta (Polychaeta) collected in unpolluted (UP) and polluted (P) sites. In the acute assay (125 and 250 micro g Cu/l) superoxide dismutase (SOD) and glutathione S-transferase (GST) activities did not change, whereas catalase (CAT) increased in worms from both the sites. Lipid peroxidation was higher in copper exposed worms from the P site. In the chronic assay (62.5 micro g Cu/l) polychaetes from the P site showed enhanced activities of SOD, GST and CAT and higher contents of metallothionein-like proteins and sulfhydrils compared to worms from UP. Differences in responses between polychaetes from UP and P sites suggest that organisms from the polluted site, P, are more susceptible to oxidative stress conditions.

Analysis of Variance↗

PubMed2004

Serum leptin concentration during the terrestrial phase of the Southern elephant seal Mirounga leonina (Carnivora: Phocidae).

This study aimed to verify the serum leptin concentration during the terrestrial phase of the Southern elephant seal (Mirounga leonina) on Elephant Island (South Shetlands, Antarctica). Sera from 25 adult Southern elephant seals were analyzed. Leptin concentration was determined using the 125I radioimmunoassay method. Total protein, triglycerides, and cholesterol concentration were measured by spectrophotometric methods. Seals were grouped by sex and their physiological status (reproducing or molting seals). In reproducing seals, serum concentrations of leptin, total protein, triglycerides, and cholesterol were, respectively, 9.33+/-1.97 ng/ml, 6.87+/-0.09 g/dl, 98.26+/-2.12 mg/dl, and 232.17+/-41.18 mg/dl in males and 5.30+/-1.36 ng/ml, 6.44+/-0.29 g/dl, 109.01+/-3.34 mg/dl, and 219.20+/-26.65 in females (mean+/-1 SD). In molting seals, these values were 2.35+/-1.51 ng/ml, 7.42+/-0.25 mg/dl, 321.10+/-20.01 mg/dl, and 244.66+/-22.24 mg/dl in males and 2.94+/-1.89 ng/ml, 7.88+/-0.46 mg/dl, 197.54 mg/dl, and 224.55+/-16.70 mg/dl in females. In both males and females, there were no significant differences (P>0.05) in total protein and cholesterol concentration between reproducing and molting seals. However, both males and females showed higher leptin concentration (P<0.05) and lower triglyceride concentration (P<0.05) in the reproductive period than in the molt period. In the reproductive period, it was expected that the Southern elephant seal shows an inhibited hunger sensation, mobilizes stored energy, and stimulates the HPG axis. Results from the present study support this hypothesis and suggest that this strategy may be effected by the hormonal stimulation of leptin.

Adaptation, Physiological↗

PubMed2003

Determination of lipid peroxides in invertebrates tissues using the Fe(III) xylenol orange complex formation.

Reactive oxygen species (ROS) are subproducts of the oxidative metabolism known to initiate chain reactions with polyunsaturated fatty acids that generate lipid peroxides (LPO). The objective of this work was to adapt the ferrous oxidation/xylenol orange (FOX) assay to measure LPO in invertebrate tissues i.e.: from polychaeta (Laeonereis acuta) and crab (Chasmagnathus granulata) species. Whole polychaetes were homogenized in methanol 100%, being determined the optimal sample volume and the time required for color development. It was tested five sample volumes (8-30 microl), following color development up to 215 min. Absorbance stabilization was observed after 90 min, being linearly related with sample volume. A similar procedure was adopted for crab tissues (anterior gills, posterior gills, and hepatopancreas). Differences between species and between organs of the same species were observed when analyzed nonspecific absorbance increments after adding the standard cumene hydroperoxide (CHP). In polychaeta and crab anterior gills tissue, absorbance increments were lower (21-25%) than samples without tissue extracts (blanks) that received CHP. In crab posterior gills and hepatopancreas, the nonspecific increment was almost negligible. Correction formulae are given to account for these differences and simplified protocols for each tissue and species are also included. Great differences in the lipid peroxides content was detected between worms (127.05 +/- 19.32 nmoles CHP/g of wet tissue) respect to anterior gills, posterior gills, and hepatopancreas from the crab species (52.65 +/- 3.59, 30.54 +/- 4.73, and 48.51 +/- 8.78 nmoles CHP/g of wet tissue, respectively).

Animals↗

PubMed2003

Effect of microcystin on ion regulation and antioxidant system in gills of the estuarine crab Chasmagnathus granulatus (Decapoda, Grapsidae).

The objective of this work was to evaluate mechanisms of microcystin toxicity on crustacean species. Adult male crabs of Chasmagnathus granulatus (13.97+/-0.35 g) acclimated to low salinity (2 per thousand ) were injected with saline (control) or Microcystis aeruginosa aqueous extract (39.2 microg/l) at 24 h intervals for 48 h. After the exposure period, the anterior and posterior gills were dissected, measuring Na(+),K(+)-ATPase and glutathione-S-transferase (GST) activity. Total oxyradical scavenging capacity (TOSC) and lipid peroxides (LPO) content were also determined. Na(+),K(+)-ATPase activity in anterior gills was significantly lower in crabs injected with toxin than in control crabs, while no significant difference in the enzyme activity was detected in posterior gills. Both sodium and chloride concentration in the hemolymph were not affected by toxin exposure. Significant changes in GST activity were detected in posterior gills, with higher values being observed in the toxin-injected crabs. Crabs exposed to microcystin also showed a significant increase in the TOSC value against peroxyl radicals, for both anterior and posterior gills. Lipid peroxides level did not change in both gill types after exposure to the toxin. The increased levels of TOSC suggest the occurrence of a crab response against oxidative stress induced by toxin injection, which prevents lipid peroxidation.

Animals↗

PubMed2003

Toxic effects of microcystins in the hepatopancreas of the estuarine crab Chasmagnathus granulatus (Decapoda, Grapsidae).

Microcystins are toxins produced by cyanobacteria, being toxic to aquatic fauna. It was evaluated alternative mechanisms of microcystins toxicity, including oxidative stress and histopathology in the hepatopancreas of the estuarine crab Chasmagnathus granulatus (Decapoda, Grapsidae). Microcystins was administered to crabs (MIC group) over 1 week, whereas the control (CTR group) received the saline from cyanobacteria culture medium. At day 7, catalase activity was higher in the MIC than in the CTR group, although a decrease of activity was verified in both groups with respect to time 0. Glutathione-S-transferase activity augmented in MIC with respect to CTR, suggesting a higher conjugation rate of the toxins with glutathione. No differences were detected in the superoxide dismutase activity. Lipid peroxidation remained stable in both groups. Histopathological analyses showed that the number of B cells decreased significantly in the CTR as a possible effect of starvation, while no significant change was observed in the MIC group. The hepatopancreas from the MIC group exhibited some necrotic tubules and melanin-like deposits. Overall, results showed that some enzymes of the antioxidant defense system were activated after microcystins exposure, this response being able to maintain lipid peroxidation levels, but insufficient to completely prevent histological damage.

Animals↗

PubMed2001

Gill Na(+),K(+)-ATPase and osmoregulation in the estuarine crab, Chasmagnathus granulata Dana, 1851 (Decapoda, Grapsidae).

Some kinetic properties of gill Na(+),K(+)-ATPase of the estuarine crab, Chasmagnathus granulata, and its involvement in osmotic adaptation were analyzed. Results suggest the presence of different Na(+),K(+)-ATPase isoforms in anterior and posterior gills. They have different affinities for Na(+), but similar affinity values for K(+), Mg(2+), ATP and similar enzymatic profiles as a function of temperature of the incubation medium. Ouabain concentrations which inhibit 50% of enzyme activity were also similar in the two types of gills. Enzyme activity and affinity for Na(+) are higher in posterior gills than in anterior ones. Furthermore, affinities of Na(+),K(+)-ATPase of posterior gills for Na(+) and K(+) were similar to or higher than those of gills or other structures involved in the osmoregulation in several euryaline decapod crustaceans. Acclimation to low salinity was related to a significant increase in the maximum Na(+), K(+)-ATPase activity, mainly in posterior gills. On the other hand, crab acclimation to high salinity induced a significant decrease in maximum enzyme activity, both in anterior and posterior gills. These results are in accordance to the osmoregulatory performance showed by C. granulata in diluted media, and point out the major role of posterior gills in the osmoregulation of this species.

Journal Article↗

PubMed2001

Histone deacetylase-targeted treatment restores retinoic acid signaling and differentiation in acute myeloid leukemia.

Histone deacetylase (HDAC)-dependent transcriptional repression of the retinoic acid (RA)-signaling pathway underlies the differentiation block of acute promyelocytic leukemia. RA treatment relieves transcriptional repression and triggers differentiation of acute promyelocytic leukemia blasts, leading to disease remission. We report that transcriptional repression of RA signaling is a common mechanism in acute myeloid leukemias (AMLs). HDAC inhibitors restored RA-dependent transcriptional activation and triggered terminal differentiation of primary blasts from 23 AML patients. Accordingly, we show that AML1/ETO, the commonest AML-associated fusion protein, is an HDAC-dependent repressor of RA signaling. These findings relate alteration of the RA pathway to myeloid leukemogenesis and underscore the potential of transcriptional/differentiation therapy in AML.

Acetylation↗

PubMed2001

Down-stream regions of the POZ-domain influence the interaction of the t(11;17)-associated PLZF/RARalpha fusion protein with the histone-deacetylase recruiting co-repressor complex.

INTRODUCTION: Acute promyelocytic leukemia (APL) patients with t(15;17)(PML/RARalpha positive) achieve remission upon t-RA treatment, whereas patients with t(11;17)(PLZF/RARalpha positive) do not. Both APL translocation products bind to the histone deacetylase (HD)-recruiting nuclear co-repressor complex (HD-NCR) in a ligand-dependent manner through their RARalpha portion. Differently to PML/RARalpha, PLZF/RARalpha also binds the HD-NCR in a ligand-independent manner through the PLZF portion of the fusion protein (PLZF#), which seems to be crucial for the t-RA resistance of t(11;17) APL patients. MATERIALS AND METHODS: The t-RA sensitivity of U937 cells was tested by the nitro-blue tetrazolium reduction (NBT) assay and by analysis of t-RA-induced type II transglutaminase activity. The interaction between HD-NCR and PLZF/RARalpha was investigated by in vitro binding assays. RESULTS: (i) Deletions in PLZF# convert PLZF/RARalpha from a repressor to an activator of t-RA response in U937 cells; (ii) the effect of PLZF/RARalpha on t-RA-signaling is regulated by the POZ-domain and its down-stream regions of PLZF#; (iii) there are additional binding sites for HD-NCR in PLZF# and (iv) PLZF# not only directly binds but also regulates the binding of PLZF/RARalpha to the HD-NCR. CONCLUSIONS: At least two different mechanisms responsible for the aberrant recruitment of HD-NCR complexes by PLZF# are regulating the different t-RA-sensitivity of the PLZF/RARalpha and PML/RARalpha positive APL blasts: one is related to the direct binding of the different members of the HD-NCR complex to PLZF#; the other is an enforcing effect of PLZF# on the affinity of the PLZF/RARalpha fusion protein to the HD-NCR complex.

Chromosomes, Human, Pair 11↗

PubMed2001

Laser thermal ablation in the treatment of small hepatocellular carcinoma: results in 74 patients.

PURPOSE: To evaluate the safety, local effectiveness, and long-term results of laser thermal ablation (LTA) in the treatment of small hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Ninety-two biopsies proved small HCCs (range, 0.8-4.0 cm) in 74 patients who were treated percutaneously with LTA in an outpatient clinic. A laser at a power of 5.0 W was coupled with one to four fibers that were advanced through 21-gauge needle(s) for 6-12 minutes. All lesions were evaluated with computed tomography (CT) for changes in size and vascular pattern, recurrence rates, and cumulative survival rates. Patients were examined for complications. RESULTS: No major complications occurred in 117 LTA sessions, with an average of 1.3 sessions per tumor. At 3 months, CT scans showed a nonenhancing area (complete necrosis) in 89 (97%) of 92 lesions. During follow-up (range, 6-66 months; mean, 25.3 months), 84 tumors (91%) decreased in size. The local recurrence rates (range, 1-5 years) ranged from 1.6% to 6.0%. Recurrence rates (range, 12-60 months) in other liver segments ranged from 24% to 73%. Cancer-free survival rates (range, 1-4 years) ranged from 73% to 24%. Overall survival rates were 99%, 68%, and 15% at 1, 3, and 5 years, respectively. Twenty-one patients (28%) died. CONCLUSION: LTA is a safe and effective treatment for small HCC.

Aged↗

PubMed2001

Hepatocellular carcinoma: long-term results of combined treatment with laser thermal ablation and transcatheter arterial chemoembolization.

PURPOSE: To determine the potential long-term effectiveness of laser thermal ablation (LTA) followed by transcatheter arterial chemoembolization (TACE) in the percutaneous ablation of large hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Thirty large HCCs 3.5-9.6 cm in diameter (mean diameter, 5.2 cm) and 15 small HCCs 0.8-3.0 cm (mean diameter, 1.9 cm) were treated with ultrasonographically guided LTA with TACE and with LTA alone, respectively, in 30 patients: 19 with a solitary large HCC, and 11 with one to three additional synchronous small HCCS: A 1.064-microm neodymium yttrium-aluminium-garnet (Nd-YAG) laser at a power of 5.0 W was coupled with one to four quartz optic fibers that were advanced through 21-gauge needles. Segmental TACE was performed 30-90 days after LTA. All lesions were evaluated for change in size at computed tomography (CT), alpha-fetoprotein (AFP) levels, recurrence rates, and cumulative survival rates. RESULTS: No major complications occurred in 127 LTA sessions. CT showed complete tumor necrosis in 27 (90%) of 30 large HCCS: Twenty-eight patients were followed up for 6-41 months (mean, 17.1 months). In 25 patients, all lesions appeared stable or smaller at CT. AFP levels decreased to the normal range in all patients with high pretreatment values. The 1-, 2-, and 3-year local recurrence rate was 7% in large HCCS: Complete tumor necrosis was achieved in all 15 (100%) small HCCs; none of them recurred locally. The 1-, 2-, and 3-year cumulative survival rates were 92%, 68%, and 40%, respectively. CONCLUSION: LTA followed by TACE is an effective palliative therapy in treating large HCCS:

Aged↗

PubMed2001

Effects of Anabaena spiroides (Cyanobacteria) aqueous extracts on the acetylcholinesterase activity of aquatic species.

The effects of aqueous extracts from a cyanobacteria species, Anabaena spiroides, on fish (Odontesthes argentinensis), crab (Callinectes sapidus), and purified eel acetylcholinesterase (AChE) activity were studied. In vitro concentrations of A. spiroides aqueous extract that inhibited 50% of enzyme activity (IC50) were 23.0, 17.2, and 45.0 mg/L of lyophilized cyanobacteria for eel, fish, and crab AChE, respectively. Eel AChE inhibition follows pseudo-first-order kinetics, the same expected for organophosphorus pesticides. Inhibition of purified eel AChE using mixtures of bioxidized malathion and aqueous extract of A. spiroides showed a competitive feature (p < 0.05), suggesting that the toxin(s) could be structurally similar to an organophosphorus pesticide and that toxins present in the aqueous extract inhibit the active site of the enzyme. The inhibition recovery assays using 2-PAM (0.3 mM) showed that (1) bioxidized malathion inhibited 27.0 +/- 1.1% of crab and 36.5 +/- 0.1% of eel AChE activities; (2) with bioxidized malathion + 2-PAM the registered inhibition was 13.2 +/- 2.1% and 3.7 +/- 0.5% in crab and eel AChE, respectively; (3) the aqueous extract from A. spiroides inhibited 17.4 +/- 2.2% and 59.9 +/- 0.5% of crab and eel AChE activity, respectively; and (4) aqueous extract + 2-PAM inhibited 22.3 +/- 2.6 and 61.5 +/- 0.2% of crab and eel AChEs. The absence of enzyme activity recovery after 2-PAM exposure could imply that the enzyme aging process was extremely quick.

Acetylcholinesterase↗

PubMed2000

Altered ligand binding and transcriptional regulation by mutations in the PML/RARalpha ligand-binding domain arising in retinoic acid-resistant patients with acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by a specific translocation, t(15;17), that fuses the promyelocytic leukemia (PML) gene with the RA receptor RARalpha. Pharmacologic doses of retinoic acid (RA) induce differentiation in human APL cells and complete clinical remissions. Unfortunately, APL cells develop resistance to RA in vitro and in vivo. Recently, mutations in PML/RARalpha have been described in APL cells from patients clinically resistant to RA therapy. The mutations cluster in 2 regions that are involved in forming the binding pocket for RA. These mutant PML/RARalpha proteins have been expressed in vitro, which shows that they cause a diversity of alterations in binding to ligand and to nuclear coregulators of transcription, leading to varying degrees of inhibition of retinoid-induced transcription. This contrasts with the nearly complete dominant negative activity of mutations in PML/RARalpha previously characterized in cell lines developing RA resistance in vitro. Current data from this study provide additional insight into the molecular mechanisms of resistance to RA and suggest that alterations in the ability of mutants to interact with coregulators can be determinant in the molecular mechanism of resistance to RA. In particular, ligand-induced binding to the coactivator ACTR correlated better with transcriptional activation of RA response elements than the ligand-induced release of the corepressor SMRT. The diversity of effects that are seen in patient-derived mutations may help explain the partial success to date of attempts to overcome this mechanism of resistance in patients by the clinical use of histone deacetylase inhibitors.

Amino Acid Substitution↗

PubMed2000

Lipid peroxidation induced by Clinostomum detruncatum in muscle of the freshwater fish Rhamdia quelen.

The effect of Clinostomum detruncatum metacercaria infection on the activities of the antioxidant enzymes superoxide dismutase and catalase in muscle of the freshwater fish Rhamdia quelen was analyzed. Tert-butyl hydroperoxide-initiated chemiluminescence, a measure of lipid peroxidation, was also investigated. Enzyme activities were similar in infected and uninfected fishes. However, the chemiluminescence was almost 2-fold higher in muscle of infected fishes than in muscle of uninfected ones. These results indicate that parasite infection induces oxidative stress and a higher level of membrane damage in the fish muscle due to an imbalance between pro-oxidants and non-enzymatic antioxidants. Our results suggest that fish response to parasite infection could involve, as in other vertebrates, reactive oxygen intermediates.

Animals↗