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Biomedical subjects

M Franco

Publications and source records attributed to M Franco.

At least 37 records · Page 2Linked to original sources
PubMed2003

High frequency of Paracoccidioides brasiliensis infection in armadillos (Dasypus novemcinctus): an ecological study.

The fungus Paracoccidioides brasiliensis has been isolated from nine-banded armadillos (Dasypus novemcinctus) in different regions where paracoccidiodomycosis (PCM) is endemic. The link between PCM and these animals has provided the first valuable clue in the effort to elucidate the ecological niche of P. brasiliensis. The present study was aimed at correlating P. brasiliensis infection in armadillos with local ecological features and, if possible, the presence of the fungus in the soil in the Botucatu hyperendemic area of PCM. In this region the mean temperature ranges from 14.8 to 25.8 degrees C and the annual average precipitation is 1520 mm. The sites where 10 infected animals (positive group) were collected were studied and compared with the sites where five uninfected animals were found. The occurrence of the fungus in soil samples collected from the positive armadillos' burrows and foraging sites was investigated by the indirect method of animal inoculation. Environmental data from the sites of animal capture, such as temperature, rainfall, altitude, vegetation, soil composition, presence of water and proximity of urban areas, were recorded. All 37 soil samples collected from the sites had negative fungal cultures. Positive animals were found much more frequently in sites with disturbed vegetation, such as riparian forests and artificial Eucalyptus or Pinus forests, in altitudes below 800 m, near water sources. The soil type of the sites of positive animals was mainly sandy, with medium to low concentrations of organic matter. The pH was mainly acidic at all the sites, although the concentrations of aluminum cations (H+Al) were lower at the sites where positive animals were found. Positive armadillos were also captured in sites very close to urban areas. Our data and previous studies indicate that P. brasiliensis occurs preferentially in humid and shady disturbed forests in a strong association with armadillos.

Animals↗
PubMed2002

Femtosecond laser-induced damage and filamentary propagation in fused silica.

Bulk damage induced by fs IR laser pulses in silica is investigated both experimentally and numerically. In a strong focusing geometry, a first damage zone is followed by a narrow track with submicron width, indicating a filamentary propagation. The shape and size of the damage tracks are shown to correspond to the zone where the electron density created by optical field ionization and avalanche is close to 10(20) cm(-3). The relative role of avalanche and photoionization is studied. The plasma density produced in the wake of the pulse is shown to saturate around 2-4x10(20) cm(-3).

Journal Article↗
PubMed2002

Changes in GABA(A) receptor gene expression induced by withdrawal of, but not by long-term exposure to, zaleplon or zolpidem.

The effects of long-term treatment with and subsequent withdrawal of the two hypnotic drugs zaleplon and zolpidem on the abundance of gamma-aminobutyric acid type A (GABA(A)) receptor subunit mRNAs in cultured rat cerebellar granule cells were investigated. Incubation of neurons with either drug at a concentration of 10 microM for 5 days did not significantly affect the amounts of mRNAs encoding the alpha(1), alpha(4), beta(1), beta(2), beta(3), gamma(2)L, or gamma(2)S subunits. As expected, similar treatment with the nonselective benzodiazepine diazepam resulted in a decrease in the abundance of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. Withdrawal of zaleplon or zolpidem, like that of diazepam, induced a marked increase in the amount of the alpha(4) subunit mRNA. In addition, discontinuation of treatment with either hypnotic drug resulted in a decrease in the amounts of alpha(1), beta(2), gamma(2)L, and gamma(2)S subunit mRNAs as well as an increase in that of the beta(1) subunit mRNA. These effects of zaleplon and zolpidem on GABA(A) receptor gene expression are consistent with the reduced tolerance liability of these drugs, compared with that of diazepam, as well as with their ability to induce both physical dependence and withdrawal syndrome.

Acetamides↗
PubMed2002

Radiographic follow-up of a phalangeal brown tumor.

We report the 6-year radiographic follow-up of a phalangeal brown tumor in a patient with severe hyperparathyroidism secondary to chronic renal failure treated with hemodialysis. The phalangeal lesion increased in size during the first 3 years, until the patient finally accepted to undergo parathyroidectomy. The initial radiographic change was a small intracortical lytic area. Two years later, an expansile cystic lesion was visible in the phalanx, and computed tomography showed a cortical defect. Ossification of the lesion occurred over the 2.5 years following parathyroidectomy. The epidemiology, radiographic changes and post-treatment evolution of brown tumor in dialysed patients is reviewed. Surgical parathyroidectomy is the standard treatment for brown tumor complicating secondary hyperparathyroidism. The usefulness and limitations of treatment with vitamin D analogs, recently reported in a few case reports, are discussed.

Fingers↗
PubMed2002

Adenosine participates in regulation of smooth muscle relaxation in aortas from rats with experimental hypothyroidism.

The contribution of adenosine receptors was evaluated in vascular relaxation in experimental hypothyroidism. Hypothyroid aortic rings contracted less than normal controls with noradrenaline, phenylephrine, and KCl; the difference was maintained after incubation with 1,3-dipropyl-8-p-sulfophenylxanthine (an A1 and A2 adenosine receptor blocker). The vascular relaxation induced by acetylcholine or carbachol was similar in normal and hypothyroid aortic rings. However, adenosine, N6-cyclopentyladenosine (an A1 adenosine receptor analogue), and 5'-N-ethylcarboxamidoadenosine (an A2 and A3 adenosine analogue) induced vasodilation that was larger in hypothyroid than in normal aortas. Nomega-nitro-L-arginine methyl ester shifted the dose-response curves of adenosine, N6-cyclopentyladenosine, or 5'-N-ethylcarboxamidoadenosine to the right in both normal and hypothyroid vessels. The blocker 1,3-dipropyl-8-p-sulfophenylxanthine significantly reduced adenosine-induced relaxation in the hypothyroid but not in the normal aortic vessels. These results suggest that in hypothyroid aortas, a larger adenosine-mediated vasodilation is observed probably due to an increase in receptor number or sensitivity.

Adenosine↗
PubMed2001

Self-guided propagation of ultrashort IR laser pulses in fused silica.

We report self-guided propagation of ultrashort IR laser pulses in fused silica over several Rayleigh lengths. Self-guiding is accompanied by pulse splitting and time compression. Numerical simulations involving pulse self-focusing, temporal dispersion, and multiphoton ionization are found to be in good agreement with the experimental results. They show that a quasidynamic equilibrium between multiphoton ionization and self-focusing drives the filamentation process, while temporal dispersion plays a negligible role.

Journal Article↗
PubMed2001

Femtosecond laser-guided electric discharge in air.

The filament due to the self-guided propagation of an infrared femtosecond laser pulse in atmospheric-pressure air is used to trigger and guide an electric discharge. The long low density plasma channel due to the filament is first heated by the Joule effect during an initial transient plasma stage. The heated channel of recombined gas then hydrodynamically expands radially. The onset of a discharge starts when the density depression on axis reaches the threshold discharge value. This model is supported by detailed experimental and numerical analysis.

Journal Article↗
PubMed2001

Clearance of human herpesvirus 8 from blood and regression of leukopenia-associated aggressive classic Kaposi's sarcoma during interferon-alpha therapy: a case report.

A human immunodeficiency virus-negative woman with severe classic Kaposi's sarcoma, idiopathic leukopenia, and massive spread of human herpesvirus 8 (HHV-8) in circulating cells showed stable disease remission in response to systemic interferon-alpha treatment that was accompanied by increased CD3(+) and CD4(+) T cell numbers and complete clearance of HHV-8 from the circulation. These results suggest a direct relationship between HHV-8 clearance from blood and regression of Kaposi's sarcoma and are consistent with the in vitro inhibitory effects of interferon-alpha on HHV-8 infection.

Antiviral Agents↗
PubMed2001

Evaluation of in vitro percutaneous absorption of lorazepam and clonazepam from hydro-alcoholic gel formulations.

Clonazepam and lorazepam are two anxiolytics, antidepressant agents, having suitable features for transdermal delivery. The objectives of this study were to evaluate the in vitro percutaneous absorption of these drugs through excised human skin (stratum corneum and epidermis, SCE) and to determine their in vitro permeation behavior from a series of hydro-alcoholic gel formulations containing various enhancing agents. The best permeation profile was obtained for both drugs applying them together with Azone in combination with propylene glycol (PG): these enhancers were able to increase the clonazepam and lorazepam percutaneous fluxes at steady-state about threefold, compared to the free enhancer formulations (Control). To explain the mechanism of the used promoters, the benzodiazepine diffusion and partitioning coefficients from the gel containing the enhancers were calculated. The results indicated that the Azone in combination with PG could act by increasing the benzodiazepine diffusion coefficients, Transcutol increased only the SC/vehicle partition coefficients, limonene in combination with PG appeared to increase both partition and diffusion coefficients moderately, while PG did not increase both the parameters. Furthermore, to evaluate the potential application of tested benzodiazepine formulations containing Azone in combination with PG using the flux values from the in vitro experiments, the corresponding steady-state plasma concentrations (C(SS)) were calculated. The obtained calculated C(SS) values are within the lorazepam therapeutic range and suggest that transdermal delivery of this drug could be regarded as feasible.

Adult↗
PubMed2001

Dissolution properties and anticonvulsant activity of phenytoin-polyethylene glycol 6000 and -polyvinylpyrrolidone K-30 solid dispersions.

Solid dispersions of phenytoin in polyethylene glycol 6000 and polyvinylpyrrolidone K-30 with different drug-to-carrier ratios were prepared by the solvent method with the aim of increasing dissolution rate and bioavailability of the drug. These new formulations were characterized in the solid state by FT-IR spectroscopy, X-ray powder diffraction, and differential scanning calorimetry. Drug solubility and dissolution rate are improved by these formulations, particularly with SDPEG 1/20 and SDPVP 1/20 systems. Storage was found to influence the stability of the solid dispersions. By maximal electroshock test, it was found that the intraperitoneal administration in mice of the SDPEG 1/20 and SDPVP 1/20 systems exhibited anticonvulsant activity similar to diphenylhydantoin sodium salt.

Animals↗
PubMed2001

Breakup and fusion of self-guided femtosecond light pulses in air.

We report experiments showing the breakup and the merging of filaments formed by the modulational instability of femtosecond optical pulses in air. For input powers as high as 25 times the self-focusing threshold, the beams are shown to split into two spots, which coalesce into a self-guided beam. This effect occurs in an optically Kerr regime and plays an important role in the guiding process. Numerical simulations and theoretical estimates both support the comparison with the experimental data.

Journal Article↗
PubMed2001

Specificities for the small G proteins ARF1 and ARF6 of the guanine nucleotide exchange factors ARNO and EFA6.

ARF1 and ARF6 are distant members of the ADP-ribosylation factor (ARF) small G-protein subfamily. Their distinct cellular functions must result from specificity of interaction with different effectors and regulators, including guanine nucleotide exchange factors (GEFs). ARF nucleotide-binding site opener (ARNO), and EFA6 are analogous ARF-GEFs, both comprising a catalytic "Sec7" domain and a pleckstrin homology domain. In vivo ARNO, like ARF1, is mostly cytosolic, with minor localizations at the Golgi and plasma membrane; EFA6, like ARF6, is restricted to the plasma membrane. However, depending on conditions, ARNO appears active on ARF6 as well as on ARF1. Here we analyze the origin of these ARF-GEF selectivities. In vitro, in the presence of phospholipid membranes, ARNO activates ARF1 preferentially and ARF6 slightly, whereas EFA6 activates ARF6 exclusively; the stimulation efficiency of EFA6 on ARF6 is comparable with that of ARNO on ARF1. These selectivities are determined by the GEFs Sec7 domains alone, without the pleckstrin homology and N-terminal domains, and by the ARF core domains, without the myristoylated N-terminal helix; they are not modified upon permutation between ARF1 and ARF6 of the few amino acids that differ within the switch regions. Thus selectivity for ARF1 or ARF6 must depend on subtle folding differences between the ARFs switch regions that interact with the Sec7 domains.

ADP-Ribosylation Factor 1↗
PubMed2001

Development and validation of a spatially explicit individual-based mixed crop growth model.

Spatial disposition of plants in intercrops, and differences in sowing time between species, can strongly affect their ecological interactions and, in consequence, the system's viability and performance. Empirical exploration of a wide range of spatial and temporal plant arrangements is costly and time-consuming. Modelling the growth of mixed crops is a tool which, combined with empirical tests, can greatly reduce the time and investment required for this task. Spatially explicit, individual-based dynamic models seem well suited for this purpose; their exploration and experimental validation for the case of simple, two-species, artificial plant communities, can also provide further insight as to how the spatial and temporal scales of a plant's multispecific neighbourhood affect its growth and performance. The aim of this investigation was to further develop a published spatially explicit individual-based mixed crop growth model [Vandermeer, J. H. (1989). The Ecology of Intercropping, Cambridge, U.K.: Cambridge University Press, p. 237], and to validate it experimentally. With this purpose in mind: (1) computer programs to simulate individual plant growth and to perform statistical analysis of both deterministic and stochastic versions of the model were developed; (2) the model was parametrized using a complex experimental diculture with several cohorts and spatial arrangements; (3) the predictive capacity of the model was tested using independent spatio-temporal experimental arrangements; (4) a modified version of the model was written, which abandons the assumption of linearity of the neighbourhood index at the cost of increasing the number of parameters; (5) The performance of stochastic versions of both Vandermeer's and our modified model were compared, employing a non-parametric measure of goodness of fit. We conclude that this approach to modelling plant growth subject to intra and interspecific competition is a remarkably efficient, general, conceptually elegant, heuristic tool whose predictive power can be further improved when nonlinear terms are introduced into the neighbourhood competition index, as done in our modified version of Vandermeer's model.

Agriculture↗
PubMed2001

Monitoring of intragraft and peripheral blood TIRC7 expression as a diagnostic tool for acute cardiac rejection in humans.

T-cell immune response cDNA 7 (TIRC7) is a recently described T-cell costimulatory molecule that exhibits a central role in T-cell activation in vitro and in vivo. The present study was undertaken to investigate association between intragraft and peripheral blood mononuclear cell (PBMC) TIRC7 mRNA levels and cardiac allograft rejection in humans. TIRC7 gene expression levels were determined by a quantitative-competitive reverse transcriptase-polymerase chain reaction (QC-RT-PCR) in endomyocardial biopsies and in PBMC from cardiac transplant recipients. Biopsies collected during rejection or up to 15 days before rejection showed heightened TIRC7 mRNA expression in comparison with biopsies without rejection. All prerejection and rejection biopsies showed TIRC7 mRNA upregulation, while this was present in only 30% of the biopsies without rejection. Regarding TIRC7 mRNA in PBMC, transplant recipients showed lower levels than healthy individuals and, in contrast to the results obtained in biopsies, the levels were lower during rejection than in rejection-free periods. In summary, TIRC7 mRNA expression levels increase in biopsies and decrease in peripheral blood during acute cardiac rejection. We conclude that intragraft detection of TIRC7 transcripts is a useful tool not only for the diagnosis but also for the prediction of acute heart allograft rejection episodes.

Gene Expression↗
PubMed2001

[Clinical Characteristics and Evolution of Recurrent Infectious Endocarditis in non Drug Addicts].

INTRODUCTION AND OBJECTIVES: Recurrence of infection is observed in a high proportion of patients who have had infective endocarditis in the past. The aim of our study was to evaluate the possible differences between the first and the recurrent episodes of endocarditis, as well as to assess the outcome and prognosis of patients with recurrent endocarditis. PATIENTS AND METHOD: We reviewed a series of 13 episodes of recurrent endocarditis from among 196 cases of infective endocarditis involving non-drug-addict patients in two hospitals from 1987 to 2000. RESULTS: There were no differences between recurrent and first episodes of endocarditis according to age, sex, heart valve involved or causal microorganisms. Prosthetic valve endocarditis was more common in patients with recurrent endocarditis (86% versus 27%; p < 0.001). Although there were no differences in the rate of complications or early surgery, overall mortality was significantly higher in patients with recurrent endocarditis (53% versus 27%: p < 0.05). When early and late mortality were analysed separately, the differences did not achieve significance. CONCLUSIONS: Recurrent endocarditis was frequent in our series (7% of all cases). The features were similar to those of the first episode except for a higher rate of prosthetic valve endocarditis and a higher overall mortality.

Endocarditis, Bacterial↗
PubMed2001

Synthesis, in vitro and in vivo cytotoxicity, and prediction of the intestinal absorption of substituted 2-ethoxycarbonyl-imidazo[2,1-b]benzothiazoles.

The imidazobenzothiazole compounds 3-17 together with the imidazobenzoxazole 18, and the imidazobenzoimidazole 19 were prepared and their cytotoxic activity evaluated at the National Cancer Institute (NCI) for testing against a panel of approximately 60 tumor cell lines. Compounds 5, 7, 8, and 16 exhibited interesting in vitro cytotoxic activity. The most active imidazobenzothiazole derivative 8 was further evaluated as a cytotoxic agent in the hollow fiber assay and showed a score greater than the minimum values for xenograft testing together with a net cell kill. Comparison with the results displayed in the in vivo assay by standard antitumor drugs in clinical use revealed a significant in vivo activity of the benzothiazole compound. COMPARE analyses for compounds 4-19 against the NCI's standard agent database show poor or no correlation, and it might suggest for these compounds a mechanism of action unrelated to that of any known drug. Furthermore, the benzothiazole 8 did not show significant antitumor activity in a panel of two xenotransplanted tumors (i.e. colon and non-small cell lung tumors). By computing the polar surface area of compounds 3-19 with the MAREA computer program it was established that the most active compounds 5, 7, 8, and 16 should experience good intestinal permeability.

Animals↗