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1.
Phys Rev Lett ; 124(19): 197002, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32469576

RESUMEN

Quantization effects due to topological invariants such as Chern numbers have become very relevant in many systems, yet key quantities such as the quantum geometric tensor providing local information about quantum states remain experimentally difficult to access. Recently, it has been shown that multiterminal Josephson junctions constitute an ideal platform to synthesize topological systems in a controlled manner. We theoretically study properties of Andreev states in topological Josephson matter and demonstrate that the quantum geometric tensor of Andreev states can be extracted by synthetically polarized microwaves. The oscillator strength of the absorption rates provides direct evidence of topological quantum properties of the Andreev states.

2.
Phys Rev Lett ; 117(19): 197202, 2016 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-27858451

RESUMEN

We study the ground-state cooling of a mechanical oscillator linearly coupled to the charge of a quantum dot inserted between a normal metal and a superconducting contact. Such a system can be realized, e.g., by a suspended carbon nanotube quantum dot with a capacitive coupling to a gate contact. Focusing on the subgap transport regime, we analyze the inelastic Andreev reflections which drive the resonator to a nonequilibrium state. For small coupling, we obtain that vibration-assisted reflections can occur through two distinct interference paths. The interference determines the ratio between the rates of absorption and emission of vibrational energy quanta. We show that ground-state cooling of the mechanical oscillator can be achieved for many of the oscillator's modes simultaneously or for single modes selectively, depending on the experimentally tunable coupling to the superconductor.

3.
Phys Rev Lett ; 113(4): 047201, 2014 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-25105648

RESUMEN

We study the nonequilibrium steady state of a mechanical resonator in the quantum regime realized by a suspended carbon nanotube quantum dot in contact with two ferromagnets. Because of the spin-orbit interaction and/or an external magnetic field gradient, the spin on the dot couples directly to the flexural eigenmodes. Accordingly, the nanomechanical motion induces inelastic spin flips of the tunneling electrons. A spin-polarized current at finite bias voltage causes either heating or active cooling of the mechanical modes. We show that maximal cooling is achieved at resonant transport when the energy splitting between two dot levels of opposite spin equals the vibrational frequency. Even for weak electron-resonator coupling and moderate polarizations we can achieve ground-state cooling with a temperature of the leads, for instance, of T = 10 ω.

4.
Hum Exp Toxicol ; 37(7): 697-703, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28905663

RESUMEN

BACKGROUND: Limited information exists about epidemiology and management of mushroom poisoning. We analyzed and described epidemiology, clinical presentation, and clinical course of mushroom-poisoned patients admitted to emergency departments (EDs) of the Province of Parma, Italy. METHODS: Data from the database of mycological service were matched with clinical information retrieved from hospitals' database, from January 1, 1996 to December 31, 2016. RESULTS: Mycologist consultation was obtained in 379/443 identified mushroom poisonings. A remarkable seasonality was found, with significant peak in autumn. Thanks to the collaboration, the implicated species could be identified in 397 cases (89.6%); 108 cases (24.4%) were due to edible mushrooms, Boletus edulis being the most represented (63 cases). Overall, 408 (92%) cases presented with gastrointestinal toxicity. Twenty cases of amatoxin poisoning were recorded (11 Amanita phalloides and 9 Lepiota brunneoincarnata). One liver transplantation was needed. We observed 13 cases of cholinergic toxicity and 2 cases of hallucinogenic toxicity. Finally, 46 cases were due to "mixed" toxicities, and a total of 69 needed hospitalization. CONCLUSIONS: Early identification and management of potentially life-threatening cases is challenging in the ED, so that a mycologist service on call is highly advisable, especially during periods characterized by the highest incidence of poisoning.


Asunto(s)
Intoxicación por Setas/epidemiología , Agaricales , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Humanos , Italia/epidemiología , Intoxicación por Setas/terapia , Embarazo
5.
J Med Chem ; 39(22): 4396-405, 1996 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-8893834

RESUMEN

Three new series of tricyclic pyridazinones have been synthesized and tested in vitro in order to assess (i) their ability to inhibit aldose reductase enzyme (ALR2) and (ii) their specificity toward the target enzyme with respect to other related oxidoreductases, such as aldehyde reductase, sorbitol dehydrogenase, and glutathione reductase. The inhibitory capability of the most effective compounds (IC50 values ranging from 6.44 to 12.6 microM) appears to be associated with a rather significant specificity for ALR2. Molecular mechanics and molecular dynamic calculations performed on the ALR2-inhibitor complex give indications of specific interaction sites responsible for the binding, thus providing information for the design of new inhibitors with improved affinity for the enzyme.


Asunto(s)
Aldehído Reductasa/antagonistas & inhibidores , Modelos Moleculares , Piridazinas/química , Animales , Bovinos , Glutatión Reductasa/metabolismo , L-Iditol 2-Deshidrogenasa/metabolismo , Conformación Molecular , Conformación Proteica , Relación Estructura-Actividad
6.
J Med Chem ; 42(11): 1894-900, 1999 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-10354397

RESUMEN

The isoxazolo-[3,4-d]-pyridazin-7-(6H)-one (2) and its corresponding open derivatives 5-acetyl-4-amino-(4-nitro)-6-substituted-3(2H)pyridazinones (3, 4) were used as simplified substrates for the synthesis of new aldose reductase inhibitors with respect to the previously reported 5, 6-dihydrobenzo[h]cinnolin-3(2H)one-2 acetic acids (1). Moreover, a few derivatives lacking the 5-acetyl group were prepared. Several compounds derived from 2 displayed inhibitory properties comparable to those of Sorbinil. In this class the presence at position 6 of a phenyl carrying an electron-withdrawing substituent proved to be beneficial, independently from its position on the ring (5g,j-l). Acetic acid derivatives were more effective than propionic and butyric analogues. On the contrary, all the monocyclic compounds (6-8) were either inactive or only weakly active. The 3-methyl-4-(p-chlorophenyl)isoxazolo-[3,4-d]-pyridazin-7-(6H )-one acetic acid (5g), which proved to be the most potent derivative, was also investigated in molecular modeling studies, to assess possible similarities in its interaction with the enzyme, with respect to the model 1.


Asunto(s)
Aldehído Reductasa/antagonistas & inhibidores , Inhibidores Enzimáticos/síntesis química , Isoxazoles/síntesis química , Piridazinas/síntesis química , Aldehído Reductasa/química , Animales , Bovinos , Inhibidores Enzimáticos/química , Isoxazoles/química , Cristalino/enzimología , Modelos Moleculares , Piridazinas/química , Relación Estructura-Actividad
7.
J Med Chem ; 42(11): 1881-93, 1999 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-10354396

RESUMEN

Starting from the inhibitory activity of the flavonoid Quercetin, a series of 4H-1-benzopyran-4-one derivatives was synthesized and tested for inhibition of aldose reductase, an enzyme involved in the appearance of diabetic complications. Some of the compounds obtained display inhibitory activity similar to that of Sorbinil but are more selective than Quercetin and Sorbinil with respect to the closely related enzyme, aldehyde reductase, and also possess antioxidant activity. Remarkably, these compounds possess higher pKa values than carboxylic acids, a characteristic which could make the pharmacokinetics of these compounds very interesting. Molecular modeling investigations on the structures of inhibitors bound at the active site of aldose reductase were performed in order to suggest how these new inhibitors might bind to the enzyme and also to interpret structure-activity relationships.


Asunto(s)
Aldehído Reductasa/antagonistas & inhibidores , Antioxidantes/síntesis química , Benzopiranos/síntesis química , Inhibidores Enzimáticos/síntesis química , Aldehído Reductasa/química , Animales , Antioxidantes/química , Benzopiranos/química , Bovinos , Inhibidores Enzimáticos/química , Humanos , Riñón/enzimología , Cristalino/enzimología , Lipoproteínas LDL/química , Lipoproteínas VLDL/química , Modelos Moleculares , Oxidación-Reducción , Relación Estructura-Actividad
8.
Eur J Med Chem ; 36(9): 697-703, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11672879

RESUMEN

On the basis of the results of molecular modelling studies performed on the aldose reductase (ALR2) inhibitor 7-hydroxy-2-(4'-hydroxybenzyl)-4H-1-benzopyran-4-one (compound A) bound at the active site of the enzyme, we synthesised and tested on bovine and human ALR2 several derivatives modified at position 2 of the benzopyran moiety, in order to confirm the hypothesised binding mode of this compound. The substitution of the methylene bridge with the isosteric sulphur substituent gives an active derivative, while substitution with a polar NH causes a decrease in inhibitory activity; this is in accordance to the previously reported structure in which the methylene linker was found to be adjacent to a hydrophobic aminoacid (Leu300). Among the substituents at 4' position examined, the most favourable for inhibitory activity are those able to act as hydrogen bond donors, supporting the hypothesis of the importance of the interaction with Thr113 for the inhibition of the enzyme.


Asunto(s)
Aldehído Reductasa/antagonistas & inhibidores , Benzopiranos/síntesis química , Benzopiranos/farmacología , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Animales , Bovinos , Cromatografía en Capa Delgada , Humanos , Concentración 50 Inhibidora , Espectroscopía de Resonancia Magnética , Relación Estructura-Actividad
9.
Minerva Med ; 78(13): 911-4, 1987 Jul 15.
Artículo en Italiano | MEDLINE | ID: mdl-3601137

RESUMEN

Diabetes insipidus is a well-known complication of hypophyseal surgery. The case is described of a women presenting with evident polyuropolydipsic syndrome arising 9 years after transphenoidal hypophyseal adenectomy. The diagnosis insipidus diabetes was secondary to intrasellar scars revealed by a hypophyseal CAT scan. The unusually long interval between surgery and the onset of the syndrome is emphasised.


Asunto(s)
Diabetes Insípida/etiología , Hipofisectomía/efectos adversos , Neoplasias Hipofisarias/metabolismo , Prolactina/metabolismo , Adulto , Femenino , Galactorrea/etiología , Humanos , Neoplasias Hipofisarias/cirugía , Factores de Tiempo
10.
Minerva Med ; 78(17): 1291-6, 1987 Sep 15.
Artículo en Italiano | MEDLINE | ID: mdl-3670683

RESUMEN

The study was designed to assess glycaemic homeostasis in different situations of chronic stimulation of the opiate receptors by exogenous opiates. After an OGTT, levels of glycosylated haemoglobin (HbA1c) and serum fructosamine were measured in 3 groups of male drug addicts of comparable age. Group A consisted of 10 subjects undergoing substitution treatment with oral methadone. Group B consisted of 10 subjects addicted to intravenous injection of the syrup based methadone intended for oral administration. Group C consisted of 10 heroin addicts. Ten healthy subjects of the same age and sex were used as controls. Analysis of the results showed normal glucose tolerance in all groups with tendentially higher basal glycaemia levels in group B. HbA1c levels were significantly higher, though within normal limits, in group B than in either those receiving oral methadone (p less than 0.01) or the heroin addicts (p less than 0.01). The group B subjects also showed the highest fructosamine levels that were both well above normal limits and higher than those in the other groups in whom fructosamine levels were normal. The data therefore confirm normal glycaemia compensation in those taking oral methadone and in heroin addicts during the period considered. A new type of drug addiction involving the intravenous injection of methadone was also encountered. This produces an outstanding short-term change in glycaemic homeostasis and may well lead to future alterations in glucose tolerance.


Asunto(s)
Hemoglobina Glucada/sangre , Hemoglobina Glucada/metabolismo , Hexosaminas/sangre , Narcóticos , Trastornos Relacionados con Sustancias/sangre , Adulto , Glucemia/metabolismo , Fructosamina , Prueba de Tolerancia a la Glucosa , Heroína , Homeostasis , Humanos , Masculino , Metadona
11.
Farmaco ; 55(8): 544-52, 2000 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11132732

RESUMEN

Following our previous studies on pyridazinone carboxylic acids as potent and selective aldose reductase (ALR2) inhibitors, a new series of benzo[h]cinnolinone carboxylic acids, variously substituted at the positions 4, 7-10 and differently modified both at the central ring and at the acidic side chain, were synthesized and tested as inhibitors of ALR2. Comparison with previously synthesized compounds allows us to define more precisely structure-activity relationships for this class of compounds. In fact, in addition to the importance of the acidic side chain, their properties are highly influenced by the substituents present on the benzo[h]cinnolinone nucleous, with potency ranging from that of Sorbinil to very weakly active compounds.


Asunto(s)
Aldehído Reductasa/antagonistas & inhibidores , Ácidos Carboxílicos/síntesis química , Inhibidores Enzimáticos/síntesis química , Piridazinas/síntesis química , Animales , Ácidos Carboxílicos/farmacología , Bovinos , Inhibidores Enzimáticos/farmacología , Cristalino/enzimología , Espectroscopía de Resonancia Magnética , Estructura Molecular , Piridazinas/farmacología
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