Regioselective synthesis of 1,2-dihydroquinolines by a solvent-free MgBr2-catalyzed multicomponent reaction

A highly efficient and regioselective synthesis of 1,2-dihydroquinolines via a multicomponent reaction between an aniline and two ketones is described. This reaction was catalyzed by magnesium bromide and carried out under solvent-free conditions. When the reaction was performed by using 3-substituted anilines and nonsymmetrically substituted ketones, principally a single product was found among the four expected regioisomers. A variety of anilines and ketones, including cyclic ketones, were evaluated providing a series of 1,2-dihydroquinolines with diverse substitution patterns. A study of the mechanism is discussed. There is evidence of the in situ formation of the imine as a result of the reaction between the aniline and one of the ketones, before annulation to the heterocyclic ring.

Storage of classical information in quantum spins

Digital magnetic recording is based on the storage of a bit of information in the orientation of a magnetic system with two stable ground states. Here we address two fundamental problems that arise when this is done on a quantized spin: quantum spin tunneling and backaction of the readout process. We show that fundamental differences exist between integer and semi-integer spins when it comes to both reading and recording classical information in a quantized spin. Our findings imply fundamental limits to the miniaturization of magnetic bits and are relevant to recent experiments where a spin-polarized scanning tunneling microscope reads and records a classical bit in the spin orientation of a single magnetic atom.

Unprotected carotid artery stenting in symptomatic patients with high-grade stenosis: results and long-term follow-up in a single-center experience

BACKGROUND AND PURPOSE

The use of cerebral protection during CAS is an extended practice. Paradoxically it is open to question because it can lead to potential embolic complications. The aim of this study was to evaluate the safety and efficacy of CASWPD in patients with severe symptomatic carotid artery stenosis.

MATERIALS AND METHODS

A prospective study was performed including 210 consecutive patients (201 symptomatic and 9 asymptomatic) with carotid artery stenosis >70%. All patients were treated by CASWPD. Angiographic results and neurologic complications were recorded during the procedure and within 30 days after it. All patients underwent clinical evaluation and Doppler sonography follow-up at 3, 6, and 12 months after the procedure.

RESULTS

Two hundred twenty carotid arteries were treated. The average degree of stenosis was 88.9%. The procedure was successfully completed in 212 (96.4%) arteries. After stent placement, 98.6% of arteries showed no residual stenosis or <30%. Balloon angioplasty dilation before stent placement was performed in 16% of cases. During the 30-day periprocedural period, there were 3 major complications (1.4%), including 1 disabling ischemic stroke, 1 acute stent thrombosis, and 1 MI. The last 2 patients died from these complications. At 1-year follow-up 24 (12.8%) restenoses, 2 new ipsilateral strokes, 1 contralateral stroke, and 5 deaths (2.7%) had occurred. None of these deaths were related to the initial stroke.

CONCLUSIONS

In our study, unprotected stent placement in symptomatic patients with severe carotid artery stenosis has demonstrated a low incidence of complications. We believe that this is due to the reduction of maneuvering and manipulation through the stenosis and to the protective effect of the stent placement before angioplasty balloon dilation.

[Extrapulmonary and extraspinal presentation of osteoarticular tuberculosis]

BACKGROUND

How to overcome the difficulty in diagnosing extrapulmonary and extraspinal osteoarticular tuberculosis? What is the most appropriate way to manage the patient?

MATERIAL AND METHODS

Retrospective series of four cases of extrapulmonary and extraspinal osteoarticular tuberculosis (two patients with knee involvement, one patient with involvement of the carpus, and a fourth patient who presented with tenosynovitis of the anterior tibial tendon of the ankle). The time elapsed from the onset of the clinical picture to the diagnosis ranged between 7 months and 2 years. The definitive diagnosis resulted from the presence of caseating granulomas in the biopsy (3 cases), and the isolation of the bacillus in culture (3 cases) or with staining (one case). Only in one case was there lung involvement after the extrapulmonary presentation. One patient had spinal involvement in the form of epidural abscess months after the extraspinal presentation. All patients received chemotherapy. Surgery was performed in 3 of the 4 cases. The Martini assessment was used to evaluate the functional outcome.

RESULTS

In all patients the lesion was cured, with two excellent and two poor functional outcomes.

CONCLUSIONS

A high clinical suspicion index is needed to prevent a delayed diagnosis. Chemotherapy is the cornerstone of treatment. Surgery is indicated mainly as a diagnostic procedure, but partial resection of the lesion may be performed at the same time.

[Comparative analysis between breath test, serological immunoassay and rapid-urease test for detection of Helicobacter pylori infection in Mexican patients with non-investigated dyspepsia]

INTRODUCTION

There are multiple Helicobacter pylori (Hp) detection tests, some are invasive and other noninvasive. The diagnostic accuracy of these methods varies according to the prevalence of the disease.

OBJECTIVE

To determine the diagnostic accuracy of the breath test, serology and rapid urease test, considering gastric biopsy with Giemsa stain as the gold standard in Hp-infected subjects with uninvestigated dyspepsia.

METHODS

Eighty four subjects (64 women, mean age 45 years) who were referred for dyspeptic symptoms were evaluated. Also, 20 healthy volunteers (12 men, average age 38 years) were evaluated. All the subjects underwent hystological analysis with Giemsa stain, breath test (Heliprobe®), rapid urease test (CLOtest®) and serological immunoassay (Hexagon®).

RESULTS

Overall, Hp infection was diagnosed by histological analysis in 59 subjects (49 patients and 10 healthy subjects). Positivity to breath test, rapid urease test and serology were 56%, 46% and 44% respectively. Agreement with the histological analysis was 0.902 for the breath test, 0.620 for rapid urease test and 0.45 for serology. The area under the curve for the breath test was 0.95, for the rapid urease test was 0.82 and for serological test was 0.74.

CONCLUSIONS

In our population, the breath test shown to have a diagnostic accuracy equivalent to histological analysis by Giemsa in subjects with uninvestigated dyspepsia.

Inelastic electron tunneling spectroscopy of a single nuclear spin

Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance.

Efecto de tres dietas en el crecimiento de crías de cocodrilo americano Crocodylus acutus

Se estudió el efecto de tres dietas con sustitución de pescado marino (20 y 40%) por hígado de res en el crecimiento y supervivencia, así como el efecto de la temperatura en el consumo de alimento de crías de Crocodylus acutus. Los cocodrilos alimentados con la dieta de 40% de hígado tuvieron el mayor crecimiento y un 100% de supervivencia, con potencial de mayor tolerancia a condiciones invernales.

Outbreak of ataxia in pigs associated with consumption of piquillín (Condalia microphylla)

The plant piquillín (Condalia microphylla) grows in arid regions of Argentina and is the cause of mal del piquillín in cattle. The salient histologic features of this leukomyelopathy are vacuolation of white matter and axonal degeneration in the spinal cord. The histologic lesions can be experimentally reproduced in cattle and pigs by feeding milled bark of the plant, but naturally occurring piquillín toxicosis has not been reported previously in pigs. The authors report an outbreak of progressive ataxia on an Argentine hog farm, where partially consumed piquillín plants were found in the pens of affected pigs. Histologic lesions included vacuolation of white matter, edema, and mild axonal degeneration in lumbosacral segments of the cord. The diagnosis of mal del piquillín was based on the history, clinical signs, histologic changes, and elimination of other potential causes of leukomyelopathy. No new outbreaks developed after elimination of piquillín from the hog lots. Results of this investigation indicate that C microphylla toxicosis can affect pigs under natural conditions and should be included in the differential diagnosis for porcine ataxia and leukomyelopathy in regions where the plant grows.

Eco-contribution for the production of N-arylnitrones: solvent-free and assisted by microwaves

A simple green approach for the production of benzylideneaniline oxides is offered. This contribution was performed via the condensation of phenylhydroxylamine with several aryl aldehydes, in the absence of both catalyst and solvent, and using microwave irradiation as the activating reaction mode. In addition, good yields of the products were achieved in a short time. It is also worth noting that the work-up procedure is simple and the products do not require further purification. Finally, an interesting comparison without the use of microwave irradiation is also discussed.

Spin-transfer torque on a single magnetic adatom

We theoretically show how the spin orientation of a single magnetic adatom can be controlled by spin polarized electrons in a scanning tunneling microscope configuration. The underlying physical mechanism is spin assisted inelastic tunneling. By changing the direction of the applied current, the orientation of the magnetic adatom can be completely reversed on a time scale that ranges from a few nanoseconds to microseconds, depending on bias and temperature. The changes in the adatom magnetization direction are, in turn, reflected in the tunneling conductance.