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M Franco

Publications and source records attributed to M Franco.

At least 91 records · Page 5Linked to original sources
PubMed1998

Hypothyroidism renders liver mitochondria resistant to the opening of membrane permeability transition pore.

Membrane permeability was examined in liver mitochondria isolated from hypothyroid rats. It was found that such a thyroid status provides substantial protection from membrane leakiness as induced by Ca2+ loading. Thus, these mitochondria are less prone to undergoing permeability transition than mitochondria from euthyroid rats. The above conclusion was reached on the basis of the following two facts: (1) hypothyroid mitochondria are not strictly dependent on the addition of ADP to retain high matrix Ca2+ concentrations, and (2) carboxyatractyloside, antimycin A or carbonyl cyanide-m-chlorophenyl hydrazone failed to promote Ca2+ efflux. We discuss the possible relevance of the low content of membrane cardiolipin as well as the low expression of the adenine nucleotide translocase as responsible for the resistance to membrane damage.

Adenosine Diphosphate↗
PubMed1998

ARNO3, a Sec7-domain guanine nucleotide exchange factor for ADP ribosylation factor 1, is involved in the control of Golgi structure and function.

Budding of transport vesicles in the Golgi apparatus requires the recruitment of coat proteins and is regulated by ADP ribosylation factor (ARF) 1. ARF1 activation is promoted by guanine nucleotide exchange factors (GEFs), which catalyze the transition to GTP-bound ARF1. We recently have identified a human protein, ARNO (ARF nucleotide-binding-site opener), as an ARF1-GEF that shares a conserved domain with the yeast Sec7 protein. We now describe a human Sec7 domain-containing GEF referred to as ARNO3. ARNO and ARNO3, as well as a third GEF called cytohesin-1, form a family of highly related proteins with identical structural organization that consists of a central Sec7 domain and a carboxy-terminal pleckstrin homology domain. We show that all three proteins act as ARF1 GEF in vitro, whereas they have no effect on ARF6, an ARF protein implicated in the early endocytic pathway. Substrate specificity of ARNO-like GEFs for ARF1 depends solely on the Sec7 domain. Overexpression of ARNO3 in mammalian cells results in (i) fragmentation of the Golgi apparatus, (ii) redistribution of Golgi resident proteins as well as the coat component beta-COP, and (iii) inhibition of SEAP transport (secreted form of alkaline phosphatase). In contrast, the distribution of endocytic markers is not affected. This study indicates that Sec7 domain-containing GEFs control intracellular membrane compartment structure and function through the regulation of specific ARF proteins in mammalian cells.

ADP-Ribosylation Factor 1↗
PubMed1998

The interspecific mass-density relationship and plant geometry.

We present an a priori theoretical framework for the interspecific allometric relationship between stand mass and plant population density. Our model predicts a slope of -1/3 between the logarithm of stand mass and the logarithm of stand density, thus conflicting with a previously assumed slope of -1/2. Our model rests on a heuristic separation of resource-limited living mass and structural mass in the plant body. We point out that because of similar resource requirements among plants of different sizes, a nonzero plant mass-density slope is primarily defined by structural mass. Specifically, the slope is a result of (i) the physical size-dependent relationship between stem width and height, (ii) foliage-dependent demands of conductance, and (iii) the cumulative nature of structural mass. The data support our model, both when the potential sampling bias of taxonomic relatedness is accounted for and when it is not. Independent contrasts analyses show that observed relationships among variables are not significantly different from the assumptions made to build the model or from its a priori predictions. We note that the dependence of the plant mass-density slope on the functions of structural mass provides a cause for the difference from the zero slope found in the animal population mass-density relationship; for the most part, animals do not have a comparable cumulative tissue type.

Journal Article↗
PubMed1998

Propofol analogues. Synthesis, relationships between structure and affinity at GABAA receptor in rat brain, and differential electrophysiological profile at recombinant human GABAA receptors.

A number of propofol (2,6-diisopropylphenol) congeners and derivatives were synthesized and their in vitro capability to affect GABAA receptors determined by the inhibition of the specific [35S]-tert-butylbicyclophosphorothionate ([35S]TBPS) binding to rat whole brain membranes. Introduction of halogen (Cl, Br, and I) and benzoyl substituents in the para position of the phenyl group resulted in ligands with higher potency at inhibiting [35S]TBPS binding. A quantitative structure-affinity relationship (QSAR) study demonstrated that affinity is enhanced by increases in lipophilicity of the ligand whereas affinity is adversely affected by increases in size of the substituent para to the phenolic hydroxyl group. Consistent with the displacement of [35S]TBPS and with the activation of GABAA receptors, we demonstrate that ligands displaying high affinity (i.e., 2-4, and 8) are able to increase GABA-stimulated chloride currents in oocytes expressing human GABAA receptors and to directly activate chloride currents in an electrophysiological assay. Among them, compound 4 showed a rather peculiar profile in the electrophysiological examination with cloned alpha1beta2gamma2 GABAA receptors. Indeed, compared to propofol, it displayed a much greater efficacy at potentiating GABA-elicited chloride currents, but a much lower efficacy at producing a direct activation of the chloride channel in the absence of GABA. This behavior may give to compound 4 pharmacological properties that are more similar to anxiolytic and anticonvulsant drugs than to those of general anesthetics.

Anesthetics, Intravenous↗
PubMed1998

Left ventricular adaptation to chronic pressure overload induced by inhibition of nitric oxide synthase in rats.

Recent studies have indicated that chronic inhibition of nitric oxide synthase induces arterial hypertension without myocardial hypertrophy. We investigated the mechanisms of left ventricular (LV) adaptation to this condition. Also, we analyzed the effect of the angiotensin-converting enzyme inhibitor (ACEI), lisinopril, in this experimental model of ventricular pressure overload. Fifty-eight Wistar rats received eight weeks of treatment with either NW-nitro-L-arginine-methyl ester (L-NAME group, n = 19), lisinopril (LISINOPRIL group, n = 19) or the combination of both drugs (LNAMELIS group, n = 20). All results were compared to age and sex matched untreated rats (CONTROL group, n = 18). Tail-cuff blood pressure rose significantly in L-NAME treated rats (195 +/- 29 mm Hg) compared to the CONTROL (141 +/- 12 mm Hg), LISINOPRIL (97 +/- 13 mm Hg), and LNAMELIS (113 +/- 16 mm Hg) groups. There was no myocardial hypertrophy in the chronically hypertensive rats. The ventricular unstressed volume was significantly reduced in the L-NAME group (0.119 +/- 0.027 mL) compared to the CONTROL (0.158 +/- 0.026 mL) indicating a disproportional reduction in ventricular volume related to the myocardial mass. The chamber size modification resulted in a systolic stress which was comparable to the CONTROL even though the isovolumetric systolic pressure was higher. The systolic functional data indicated preserved myocardial contractility in L-NAME. LV compliance was increased in the LISINOPRIL group and myocardial passive stiffness was lower in all treated rats compared to CONTROL. We conclude that LV. adaptation to chronic pressure overload without hypertrophy involves changes in chamber geometry and myocardial diastolic mechanical properties. Also, ACEI fully prevents L-NAME induced hypertension, reduces myocyte cross-sectional area, and myocardial passive stiffness. The combination of L-NAME plus lisinopril decreases the load independent index of myocardial contractility.

Adaptation, Physiological↗
PubMed1998

Garlic prevents hypertension induced by chronic inhibition of nitric oxide synthesis.

It has been reported that garlic activates nitric oxide synthase in vitro and that chronic inhibition of nitric oxide (NO) synthesis by N omega-nitro-L-arginine-methyl-ester (L-NAME) induces arterial hypertension in rats. In this work, we studied the effect of oral administration of L-NAME for 4 weeks on control and garlic-fed rats. Basal systolic blood pressure was recorded 4 weeks after garlic supplementation, and on weeks 1, 2, 3, and 4 after L-NAME treatment. At the end of the study, the in vivo NO production was evaluated indirectly by measuring the urinary excretion of the stable end products of NO metabolism, nitrite (NO2-) and nitrate (NO3-). It was found that L-NAME induced arterial hypertension on weeks 1-4 in control rats but not in garlic-fed rats, whose blood pressure remained essentially as the basal values. Also, during this time period, blood pressure remained unchanged in garlic-fed rats without L-NAME treatment. Urinary excretion of NO2-/NO3- decreased in L-NAME-treated rats, increased in garlic-fed rats, and remained unchanged in garlic-fed rats treated with L-NAME. It was concluded that garlic blocks the L-NAME-induced hypertension by antagonizing in vivo the inhibitory effect of L-NAME on NO production.

Animals↗
PubMed1998

Infection of lepidoptera with a pseudotyped retroviral vector.

Studies requiring the introduction and expression of manipulated gene constructs have been technically difficult in non-drosophilid insects. Retroviruses can be engineered to be replication defective and to serve as vectors for gene constructs of interest. In this study, pseudotyped MoMLV(VSV-G) retroviral vectors are shown to successfully infect lepidopteran cells in vitro and in vivo. In Spodoptera frugiperda cells in vitro and in Manduca sexta in vivo, infection and conversion to proviral DNA were confirmed by PCR amplification and Southern blot hybridization of vector-specific sequences. Gene expression and integration of proviral DNA were also documented in vitro. This is the first report of retroviral infection in lepidoptera and suggests that pseudotyped retroviral vectors could be powerful tools in gene manipulation studies of non-drosophilid insects.

Animals↗
PubMed1998

Inclusion complexation of propofol with 2-hydroxypropyl-beta-cyclodextrin. Physicochemical, nuclear magnetic resonance spectroscopic studies, and anesthetic properties in rat. trapani@ippo.uniba.it.

An aqueous formulations of propofol 1 can be prepared by solubilizing it in the presence of 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD). This is potentially useful for parenteral administration of the drug. The aqueous solubility of 1 linearly increased as a function of HP-beta-CD concentration and showed features of an AL type diagram. Thermodynamic parameters were obtained by using the temperature dependence of the stability constant at temperatures of between 25 and 37 degrees C. The results indicate that complex formation is enthalpically, rather than entropically, driven and that it may involve van der Waals (dispersive) forces, rather than hydrophobic interactions. The structure of the inclusion complex propofol/HP-beta-CD was investigated in D2O, using 1H and 13C NMR spectroscopy. These studies revealed that the whole aromatic ring, as well as part of the isopropyl groups of the guest molecule, is located inside the HP-beta-CD cavity, while the hydroxy group is located at the rim of the wider cavity end. The geometrical features of the inclusion complex 1-HP-beta-CD are confirmed by 1D NOE difference spectra and molecular modeling experiments. The anesthetic activity in rat was investigated, and it was found that there are significant differences in induction time and sleeping time between 1 solubilized in the presence of HP-beta-CD and the formulation currently used (Diprivan), which is a 1% w/v oil/water emulsion.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1998

Study of pulmonary experimental paracoccidioidomycosis by analysis of bronchoalveolar lavage cells: resistant vs. susceptible mice.

Adult Swiss (susceptible) and BALB/c (non-susceptible) mice were inoculated by the intravenous route with 1 x 10(6) yeast cells of Paracoccidioides brasiliensis, strain 18. Immunologic parameters, histopathology and features of the bronchoalveolar lavage (BAL) were evaluated at week 2, 4, 8 and 16 post-infection. The pulmonary infection was progressive in Swiss mice and regressive in Balb/c mice. The numbers of total cells, lymphocytes and polymorphonuclear neutrophils increased in BAL, as well as the percentages of giant cells, and CD4 and CD8 positive cells. The ultrastructural study of BAL cells revealed a predominance of macrophages and a frequency of 13.2% of type II pneumocytes. As the infection progressed, the number of fungal cells and spreading macrophages, as well as the stimulated release of H2O2 by macrophages, increased. The animals exhibited an exacerbation of the humoral immune response and a depression of cellular immunity during the infection. There was a good correlation between the intensity and the pattern of the pulmonary histopathology and the cellular findings in the BAL. The present model reproduces some anatomoclinical patterns of the human disease and shows that BAL may be a useful tool in monitoring the pulmonary infection caused by P. brasiliensis.

Animals↗
PubMed1998

Renal effects of renin-angiotensin system blockade.

Pharmacological interruption of the renin-angiotensin system at different pathway levels has extended our knowledge on the distribution of angiotensin receptors in different nephron segments, its regulation and tubular cell responses. Novel beneficial effects obtained with blockade of this peptide on cellular proliferation and its interaction with other vasoactive systems are particularly important for preventing renal damage.

Angiotensin II↗
PubMed1998

Mapping of the T-cell epitope in the major 43-kilodalton glycoprotein of Paracoccidioides brasiliensis which induces a Th-1 response protective against fungal infection in BALB/c mice.

The 43-kDa glycoprotein of Paracoccidioides brasiliensis is the major diagnostic antigen of paracoccidioidomycosis, the prevalent systemic mycosis of Latin America. Apart from eliciting high antibody titers, gp43 is also immunodominant in delayed-type hypersensitivity reactions in infected animals and humans. The cellular immune response in mice to gp43 administered in complete Freund's adjuvant involves CD4+ Th-1 lymphocytes, secreting gamma interferon (IFN-gamma) and interleukin 2 (IL-2) but not IL-4 and IL-10. The T-cell epitope of this antigen was mapped to a 15-amino-acid peptide (P10) based on lymphoproliferations with primed cells from three different haplotypes and on a computer-assisted protein analysis. The structural requirements of the T-cell epitope were determined by assaying a series of P10 analogous and truncated peptides. Only 12-mer or longer sequences were active, confirming presentation by major histocompatibility complex II. The HTLAIR inner core of P10 is the essential domain of the epitope, with various flanking regions possible. Immunization of mice with both gp43 and P10 led to vigorous protection against intratracheal challenge by virulent P. brasiliensis, with a >200-fold decrease in lung CFU and halting of dissemination to the spleen and liver. The protective effect of P10 is mainly attributed to an IFN-gamma-mediated cellular immune response. Unlike gp43, which induces an antibody response compatible with both Th-1 and Th-2 activation in infected BALB/c mice, P10 does not induce a humoral response. Protection by gp43 and P10 was characterized by a few well-demarcated lung granulomas with numerous nonviable yeast forms or resolved lesions with no detectable fungal cells.

Animals↗
PubMed1998

Isolation of Paracoccidioides brasiliensis from armadillos (Dasypus noveminctus) captured in an endemic area of paracoccidioidomycosis.

Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis (PCM), was first isolated from armadillos from the Amazonian region where the mycosis is uncommon. In the present study, we report on the high incidence of PCM infection in armadillos from a hyperendemic region of the disease. Four nine-banded armadillos (Dasypus novemcinctus) were captured in the endemic area of Botucatu, Sao Paulo, Brazil, killed by manual cervical dislocation and autopsied under sterile conditions. Fragments of lung, spleen, liver, and mesenteric lymph nodes were processed for histology, cultured on Mycosel agar at 37 degrees C, and homogenized for inoculation into the testis and peritoneum of hamsters. The animals were killed from week 6 to week 20 postinoculation and fragments of liver, lung, spleen, testis, and lymph nodes were cultured on brain heart infusion agar at 37 degrees C. Paracoccidioides brasiliensis was isolated from three armadillos both by direct organ culture and from the liver, spleen, lung, and mesenteric lymph nodes of hamsters. In addition, one positive armadillo presented histologically proven PCM disease in a mesenteric lymph node. The three armadillos isolates (Pb-A1, Pb-A2, and Pb-A4) presented thermodependent dimorphism, urease activity, and casein assimilation, showed amplification of the gp43 gene, and were highly virulent in intratesticularly inoculated hamsters. The isolates expressed the gp43 glycoprotein, the immunodominant antigen of the fungus, and reacted with a pool of sera from PCM patients. Taken together, the present data confirm that armadillos are a natural reservoir of P. brasiliensis and demonstrate that the animal is a sylvan host to the fungus.

Animals↗
PubMed1998

Localization of eosinophil granule major basic protein in paracoccidioidomycosis lesions.

Paracoccidioidomycosis is a chronic granulomatous disease caused by the fungus Paracoccidioides brasiliensis. Although eosinophils have long been associated with the immune defense against helminths, the role of eosinophils in the immune response to fungal diseases is not as well studied. The eosinophil granule major basic protein is toxic to helminths and mammalian cells in vitro, and its release has been used as a marker of eosinophil localization and degranulation. To determine whether eosinophil infiltration and degranulation, as evidenced by the deposition of major basic protein, occur in lesions of P. brasiliensis, we used an immunofluorescence technique to localize the P. brasiliensis organisms and eosinophils and major basic protein. Initially, all tissues were stained with polyclonal antibody to major basic protein; subsequently, colocalization of major basic protein and P. brasiliensis by double staining with mouse and rabbit antibodies, respectively, was performed. Nine biopsy tissues from seven patients were analyzed. All nine biopsies showed infiltration of intact eosinophils using both the monoclonal and the polyclonal anti-major basic protein antibodies, along with the presence of P. brasiliensis. Furthermore, using the polyclonal anti-major basic protein antibody, nine of nine tissues showed extracellular major basic protein deposition (granular or diffuse fluorescence staining outside of intact eosinophils). The double staining procedure using the anti-major basic protein monoclonal antibody showed extracellular deposition in five of eight biopsies; in these five biopsies, approximately 60% of the areas containing P. brasiliensis had extracellular major basic protein deposited on the organisms. These observations support the hypothesis that the eosinophil, through toxic granule proteins such as major basic protein, participates in the pathophysiology of paracoccidioidomycosis.

Adult↗
PubMed1998

Long-term radiographic follow-up in a patient with osteosclerotic sarcoidosis of the spine and pelvis.

Eight-year clinical and radiographic data in a patient with sarcoidosis manifesting as pelvic and spinal osteosclerosis and as mediastinal lymphadenopathy are described, extending the initial report of this case written after three years of follow-up. The osteosclerotic lesions involved the right iliac and sacral wings, as well as two lumbar vertebras, which had an ivory appearance. There was also evidence of right sacroiliitis, pubic symphysitis and T7-T8 discitis. The diagnosis was established by bone and mediastinal lymph node biopsies. Follow-up was eight years at the time of this writing. The osteosclerotic lesions improved, disappearing almost completely at the lumbar spine, and fusion occurred at the right sacroiliac joint, pubic symphysis, and T7-T8 intervertebral disk. A review of the literature found 13 similar cases, with noticeably shorter follow-ups. The characteristics of axial osteosclerotic sarcoidosis are reviewed, and the indications of corticosteroid therapy are discussed.

Female↗
PubMed1997

Synthesis and binding affinity of 2-phenylimidazo[1,2-alpha]pyridine derivatives for both central and peripheral benzodiazepine receptors. A new series of high-affinity and selective ligands for the peripheral type.

A number of 6-substituted or 6,8-disubstituted alkyl 2-phenylimidazo[1,2-alpha]pyridine-3-carboxylates 5a-h, -acetates 5i-s, 6a-g, and -propionates 5t, 6h and of N,N-dialkyl-2-phenylimidazo[1,2-alpha]pyridine-3-carboxamides 7a-d,-acetamides 7e-t or -propionamide 7u were prepared following new synthetic methods, and their affinities for both the central (CBR) and the peripheral (PBR) benzodiazepine receptors evaluated. The compounds of the ester series displayed low affinity for both receptor types. Conversely, most of N,N-dialkyl(2-phenylimidazo[1,2-alpha]pyridin-3-yl)acetamides 7e-t proved to possess high affinity and selectivity for CBR or PBR depending on the nature of substituents at C(6)- and/or C(8) on the heterocyclic ring system. In particular, the 6-substituted compounds 7f-n displayed ratios of IC50 values (IC50(CBR)/IC50(PBR)) ranging from 0.32 (7m) to 232 (7k), while the 6,8-disubstituted compounds 7o-t were more than 1000-fold more selective for PBR versus CBR. Compounds 7f,m were examined in several different benzodiazepine receptor subtypes. Expression of specific GABAA, receptor subunit assemblies in Xenopus oocytes was utilized to evaluate functionally both the efficacy and potency of the positive modulation of GABA-evoked Cl- currents by 7f and 7m in comparison with Zolpidem. The rank order of potencies of these drugs was 7f (EC50 = 3.2 x 10(-8) M) > Zolpidem (EC50 = 3.6 x 10(-8) M) > 7m (EC50 = 2.2 x 10(-7) M). The actions of these compounds were also tested on alpha 2 beta 2 gamma 2s, receptors. However, the EC50 of these compounds was increased, compared to alpha 1 beta 2 gamma 2s receptors, by 30-, 4-, and 5-fold for 7m, 7f, and Zolpidem, respectively. Finally, these compounds were almost completely devoid of activity at receptors containing the alpha 5 subunit.

Animals↗
PubMed1997

Indomethacin and piroxicam inhibit Na+-adenosine transport in rat renal brush-border membranes.

The effects of the cyclooxygenase inhibitors, indomethacin and piroxicam, were evaluated on Na+-dependent [3H]adenosine transport in rat renal brush-border membranes of the outer renal cortex of the rat. Adenosine co-transport (1-10 microM) was estimated in the presence of 0.001-10 microM indomethacin and piroxicam. Both drugs inhibited the Na+-dependent transport in a dose-dependent manner with IC50 of 3.5 microM and 0.1 microM, respectively. The Na+-independent transport was not modified. Preincubations carried out on the vesicles with 10-50 microM arachidonic acid increased transport in a dose-dependent manner up to 1.7 times. Whereas 50 pM to 5 microM prostaglandin E2 in the presence of indomethacin did not change carrier activity, 5 microM prostaglandin E2 increased the Na+-dependent transport 1.5 times. Other prostanoid synthesis pathways were investigated with 10 microM nordihydroguaiaretic acid (lipoxygenase inhibitor), and 17-octadecynoic acid and clotrimazole (leukotriene and cytochrome P450 inhibitors). Our results demonstrated that the Na+-dependent adenosine transport in brush-border membranes was inhibited by indomethacin and piroxicam, suggesting that cyclooxygenase activity might modulate this co-transport.

Adenosine↗
PubMed1997

Sodium-dependent adenosine transport is diminished in brush border membrane vesicles from hypothyroid rat kidney.

Studies of the uptake of [3H]adenosine ([3H]ADO) were performed using brush border membrane vesicles (BBMV) from normal (N) and hypothyroid (Tx) rat kidneys, to test if decreased Na+ reabsorption in hypothyroidism might be associated with abnormalities in ADO transport. [3H]ADO uptake (1-10 micromol) for both conditions was measured in the presence of Na+ (10-150 mmol/l); the effects of dipyridamole (10 micromol/l) and 1, 3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX, 10 micromol/l) were also studied. Na+-stimulated ADO uptake was decreased in Tx BBMV. Michaelis-Menten constants showed a decreased ADO carrier affinity (Km 2.46 +/- 0.14 in N, vs Km 4.46 +/- 0.88 micromol/l in Tx, P<0.05), with no change in the number of carriers (Vmax 295 +/- 25 in N, vs 229.2 +/- 56 pmol.min-1.mg protein in Tx). Na+ affinity remained unchanged (K Na+ 11.5 +/- 3.5 in N, vs K Na+ 12.72 +/- 0.7 mmol/l in Tx). Inhibition of Na+-dependent ADO transport was 50% in N as opposed to 58% in Tx with dipyridamole, and 72% in N versus 47% in Tx with PACPX. These results suggest that decreased Na+-dependent ADO cotransport contributes to the diminished tubular reabsorption that occurs in hypothyroidism.

Adenosine↗