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G Vidal

Publications and source records attributed to G Vidal.

At least 19 recordsLinked to original sources
PubMed2000

Reversible combination of inequivalent kinds of multipartite entanglement.

We present a family of tripartite entangled states that, in an asymptotical sense, can be reversibly converted into Einstein-Podolsky-Rosen (EPR) states, shared by parties B and C, and tripartite Greenberger-Horne-Zeilinger (GHZ) states. Thus we show that a bipartite and a genuine tripartite entanglement can be reversibly combined in a tripartite state. For such states the corresponding fractions of GHZ and EPR states represent a complete quantification of their (asymptotical) entanglement resources. More generally, we show that AB, AC, and BC EPR entanglement and GHZ entanglement can be reversibly combined in a single tripartite state. Finally, we generalize this result to any number of parties.

Journal Article↗
PubMed2000

Aminomethylphosphonate and 2-aminoethylphosphonate as (31)P-NMR pH markers for extracellular and cytosolic spaces in the isolated perfused rat liver.

Aminomethylphosphonate (NMePo) and 2-aminoethylphosphonate (NEthPo) were evaluated as alternative pH indicators in the isolated perfused rat liver using (31)P-nuclear magnetic resonance (NMR). NMePo did not distribute within cells and remained in the extracellular space. It exhibited pH titration with a low pK(a) value (5.35). This behaviour makes NMePo useful for extracellular volume or acidic pH determination. In contrast, NEthPo accumulated within cells without altering liver energetic steady state, evaluated from nucleosides triphosphates resonances, even for prolonged (100 min) experiments. Withdrawal of NEthPo from perfusate revealed a residual resonance corresponding to the internalized amount of this phosphonate. This fraction was almost stable vs time and allowed determination of spin-lattice relaxation time constant T(1) within the liver (2.2 +/- 0.3 s; n = 6). Comparison of the titration curves for NEthPo and inorganic phosphate revealed that the accuracy of pH determination within physiologic or acidic range in both cases was comparable. Finally, when extracellular pH was decreased, the NEthPo resonance frequency was found to undergo the same chemical shift variations as observed for cytosolic P(i) signal, which was in good agreement with a cytosolic accumulation of this phosphonate. Therefore, NEthPo could be considered as an interesting cytosolic pH probe suitable for (31)P-NMR measurements, especially when experimental conditions prevent reliable observation of cytosolic Pi resonance.

Aminoethylphosphonic Acid↗
PubMed2000

Prevalence of anti-hepatitis A antibodies in an urban middle class area of Argentina: some associated factors.

OBJECTIVE: This study evaluated the seroprevalence of hepatitis A virus (HAV) antibodies in 360 middle-class subjects from Buenos Aires City and its outskirts. METHODS: The study population included 360 individuals between 10 and 89 years of age, from the socioeconomic middle class in Buenos Aires City and some suburban areas of Buenos Aires province. Antibodies to hepatitis A virus were determined by enzyme immunoassay test kits. RESULTS: The overall prevalence of HAV antibodies was 42.2%. The highest percentage of seronegativity was found in the subgroup of younger people without a history of symptomatic hepatitis and living in houses with more than one bathroom (86.9%). In the subgroup aged 21 to 60 years, the highest rates of seronegativity were found in individuals with higher level of education living in houses with tap water (66.6%). In both groups, seronegativity may be correlated with a higher socioeconomic status. CONCLUSIONS: In the middle-class community studied, more than 50% of people under 30 years of age were unprotected against HAV. Thus, the use of a vaccine against hepatitis A has to be considered for the prevention of symptomatic hepatitis, especially in adults at risk of infection, such as those who travel to areas with poor sanitation, taking into consideration that the severity of the disease increases with age.

Adolescent↗
PubMed1999

Early diagnosis of pediatric Wernicke's encephalopathy.

Wernicke's encephalopathy may be fatal if untreated. Because Wernicke's encephalopathy is suspected to be underdiagnosed in children, the authors wished to assess the frequency of overlooked diagnosis and to establish pertinent findings that could lead to early identification of pediatric Wernicke's encephalopathy. The authors performed multiple literature searches seeking pediatric patients with Wernicke's encephalopathy (age = 20 years or younger). A total of 30 patients was found, and the authors added a new patient. Each case report had its clinical, radiologic, and laboratory data, diagnostic method, and outcome analyzed. Of 31 patients, 16 were female and 15 male; the median age +/- S.D. was 11 +/- 6.5 years. The most frequent underlying disorder was malignancy in 11. Thirteen patients died undiagnosed, 16 recovered with thiamine therapy (eight with sequelae), and two died of infection soon after thiamine replacement was initiated. Only six presented with the Wernicke's encephalopathy clinical triad (mental status changes, ocular signs, and ataxia) at neurologic onset; nine eventually demonstrated this triad. The high rate of patients diagnosed only at postmortem examination (41.9%) confirms that Wernicke's encephalopathy is underdiagnosed in children. Thiamine therapy is warranted if any component of the Wernicke's encephalopathy triad is present in an appropriate clinical setting.

Adolescent↗
PubMed1998

Cytosolic pH regulation in perfused rat liver: role of intracellular bicarbonate production.

The contribution of metabolic bicarbonate to cytosolic pH (pHcyto) regulation was studied on isolated perfused rat liver using phosphorus-31 NMR spectroscopy. Removal of external HCO3- decreased proton efflux from 18.6+/-5.0 to 1.64+/-0.29 micromol/min per g liver wet weight (w.w.) and pHcyto from 7.17+/-0.06 to 6.87+/-0.06. In the nominal absence of bicarbonate, inhibition of carbonic anhydrase by acetazolamide induced a further decrease of proton efflux of 0.69+/-0.26 micromol/min per g liver w.w. reflecting a reduction in metabolic CO2 hydration, and hence a decrease of H+ and HCO3- supplies. Even though 27% of the proton efflux was amiloride-sensitive under bicarbonate-free conditions, amiloride did not change pHcyto, revealing the contribution of additional regulatory processes. Indeed, pH regulation was affected by the combined use of 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and amiloride since pHcyto decreased by 0.16+/-0.05 and proton efflux by 0.60+/-0.14 micromol/min per g liver w.w. The data suggest that amiloride-sensitive or SITS-sensitive transport activities could achieve, by themselves, pHcyto regulation. The involvement of two mechanisms, most likely Na+/H+ antiport and Na+:HCO3 symport, was confirmed in the whole organ under intracellular and extracellular acidosis. The evidence of Na-dependent transport of HCO3- in the absence of exogenous bicarbonate implies that the amount of metabolic bicarbonate is sufficient to effectively participate to pHcyto regulation.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1998

Cytosolic pH variations in perfused rat liver at 4 degrees C: role of intracellular buffering power.

The effect of low temperature on cytosolic pH regulation and buffering capacity was evaluated in the isolated rat liver. The pH changes were followed by phosphorus-31 nuclear magnetic resonance. Cooling from 37 to 4 degrees C, with Krebs-Heinseleit perfusion at an external pH of 7.35, induced an alkaline shift in cytosolic pH (pHcyt) of 0.13 or 0.75 pH units in the presence of bicarbonate, respectively (dpH cys/dT values were 0.004 and 0.022 unit/degrees C. With 4 degrees C perfusion, in the presence or absence of bicarbonate, acute changes of external pH (from 7.40 to 5.90) did not affect pHcyt. In contrast, intracellular loading with isobutyric acid or NH4Cl induced rapid pHcyt variations. The intrinsic buffering power value (10 to 50 slykes) measured in the absence of bicarbonate depended on pHcyt. The larger value was observed for pHcyt 7.30, a value near the pK value of the imidazole group of intracellular proteins at 4 degrees C. The presence of bicarbonate modified the amplitude of the pHcyt change by increasing the total buffering power. It was demonstrated that during hypothermia, ionic carriers are inactivated and the charged forms of molecules are unable to cross the cell membrane; thus, the pHcyt homeostasis depends essentially on intracellular buffering power.

Acidosis↗
PubMed1998

Squamous cell carcinoma and infection in a solitary hepatic cyst.

Solitary benign non-parasitic hepatic cysts (SBNHC) are rare congenital cystic abnormalities. Complications of SBNHC include infection, perforation, spontaneous haemorrhage, torsion and neoplastic degeneration. Squamous cell carcinoma is an exceedingly rare entity, which usually arises from metaplastic and subsequent neoplastic transformation of pre-existing cyst of the liver. We report a new case of squamous cell carcinoma of the liver in a non-parasitic solitary hepatic cyst infected by aerobic mixed flora at the time of diagnosis.

Aged↗
PubMed1997

NMR studies of inorganic phosphate compartmentation in the isolated rat liver during acidic perfusion.

Mitochondrial inorganic phosphate has been shown to be undetectable by 31P NMR in the isolated rat liver perfused under physiological conditions. Cold perfusion (4 degrees C) with valinomycin (K+ ionophore) induced the appearance of an additional resonance assigned to P(i) from mitochondrial compartment (P(i,mito)) (Thiaudière et al., 1993, FEBS Lett. 330, 232-235). Here we have demonstrated that P(i,mito) can be detected by NMR under normothermic conditions (37 degrees C) in acidic (pH 6.5, bicarbonate-free) perfused liver using 50 nM valinomycin or 10 microM N,N'-dicyclohexylcarbodiimide (DCCD, a mitochondrial H+-ATP synthase inhibitor). These conditions resulted in a significant increase in mitochondrial P(i) content. In the presence of valimomycin, pH values of 7.00+/-0.07 and 6.60+/-0.10 (n = 7) for mitochondria and cytosol, respectively, were determined from the chemical shift values of P(i) resonances. Electron microscopy demonstrated a large matrix swelling under valinomycin perfusion, explaining the increased level of mitochondrial P(i). The amount of mitochondrial P(i) measured by NMR increased linearly with the cellular ATP depletion, suggesting a mitochondrial influx of P(i) from the cytosolic compartment with valinomycin perfusion. Moreover, the level of matrix P(i) was dependent on the cytosolic pH value, the resonance being not detectable at physiological cytosolic pH. During mitochondrial swelling, P(i) influx was likely to be associated with proton influx, owing to the stability of transmembrane pH gradient and matrix proton concentration.

Adenosine Triphosphate↗
PubMed1997

[Conservative treatment of 2 tracheal lesions secondary to anesthetic intubation].

This case report describes two patients admitted to our hospital for elective surgery, one for biliary disease and the other for vascular disease. Shortly after surgery each presented a clinical picture attributable to membranous tracheal pars rupture caused by anesthetic intubation. Airway lesions were diagnosed and, after patient status was evaluated, conservative medical treatment was prescribed in both cases. Outcome was excellent, with no complications, within a few days. These cases demonstrate the efficacy of this way of managing this potentially serious complication.

Aged↗
PubMed1997

Giant cell (temporal) arteritis and secondary renal amyloidosis: report of 2 cases.

Renal involvement is unusual in giant cell (temporal) arteritis (GCA). Microscopic hematuria and minimal proteinuria responsive to steroid therapy have been described as the most frequent renal alterations. The nephrotic syndrome in GCA has been rarely reported. We describe 2 cases of GCA with nephrotic syndrome, one at the time of diagnosis, the other 2 years after treatment. Percutaneous renal biopsy in both cases disclosed secondary renal amyloidosis confirmed by permanganate sensitivity and immunohistochemical analysis. To our knowledge, cases of GCA and secondary amyloidosis have not been reported.

Aged↗
PubMed1996

Temperature dependence of NMR relaxation times of nucleoside triphosphates and inorganic phosphate in the isolated perfused rat liver. Effect on Pi compartmentation.

The effect of temperature on 31P NMR spectra from isolated perfused rat livers was studied at 9.4 T. Relaxation times (T1 and T2) of uncleoside triphosphates (NTP) and inorganic phosphate (Pi) were determined at 37, 25, 15, and 4 degrees C. Under hypothermic conditions, an unexpected apparent line sharpening in the Pi spectral region and a clear emergence of an additional Pi resonance were observed. This additional signal was assigned to mitochondrial Pi. T1 values obtained for cytosolic and mitochondrial Pi at 4 degrees C were 1.14 +/- 0.24 s (n = 5) and 0.71 +/- 0.18.s (n = 5), respectively. No significant mitochondrial contribution to the Pi resonance was observed at 37 degrees C. Quantification of Pi and NTP liver contents at 37 and 4 degrees C was performed by comparing the perfused liver spectrum and the corresponding perchloric acid extract spectrum. Under experimental conditions of low external Pi (0.12 mM), it was concluded that intracellular Pi was completely NMR-visible at 4 and 37 degrees C. The observation of the mitochondrial Pi signal at 4 degrees C was well explained by an increase in the Pi level within the matrix, in response to the mitochondrial swelling induced by hypothermia, as observed by electron microscopy. T2 values for the cytosolic Pi at 37 and 4 degrees C were 17 +/- 4 ms (n = 8) and 22 +/- 4 ms (n = 10), respectively. Comparison with measured linewidths indicated that line broadening for the main phosphorylated metabolites--including matrix Pi--was the result of B0 field inhomogeneity. The additional broadening of the cytosolic Pi resonance at 4 and 37 degrees C was attributed to pH heterogeneity within the liver.

Animals↗
PubMed1994

[40 years later].

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Argentina↗