Isabel Sousa | PubMed Health

PubMed2006

Solution studies on binary and ternary complexes of copper(II) with some fluoroquinolones and 1,10-phenanthroline: Antimicrobial activity of ternary metalloantibiotics.

Interaction of norfloxacin and ofloxacin with copper(II) and copper(II)/phenanthroline has been studied in aqueous solution and the stability constants of the binary complexes Cu(II)/fluoroquinolone and of the ternary complexes Cu(II)/phenanthroline/fluoroquinolone have been determined by potentiometry and UV-vis spectrophotometry. The stability constants for the binary and ternary complexes of norfloxacin were always higher than those found for ofloxacin and comparing the values obtained for the binary and ternary species (DeltalogK) it is possible to conclude that the ternary complexes are more stable than the binary ones, suggesting that an interaction occurs between the ligands in the ternary complexes. From the distribution diagrams it is possible to state that at physiological pH 7.4, the copper ternary complexes, are the main species in solution not only at the concentration used to determined the stability constants but also at the minimum inhibitory concentration. The antibacterial activity of these complexes, in different bacterial strains, was determined, at physiological pH, and the results obtain show that these ternary complexes may be good candidates as metalloantibiotics.

Anti-Bacterial Agents↗

PubMed2006

Recurrent syncope--a diagnostic challenge.

Several disorders resemble syncope. According to the European Society of Cardiology guidelines, certain key questions should be addressed during the initial evaluation of a patient presenting syncope. The physician should be alert to important clinical features that suggest the diagnosis and the evaluation strategy. However, syncope remains a diagnostic challenge. The authors report a case of a 60-year-old man admitted to the Emergency Department (ED) complaining of recurrent syncopal attacks that had begun one month before. He had daily transient, self-limited loss of consciousness lasting for seconds or even a few minutes, followed by prompt recovery. The attacks occurred mainly after exercise or urination. Prodromal symptoms were sweating and a sensation of imminent death. He learned to recognize these symptoms, reporting that he could control the duration of the attack by sitting down and voluntarily hyperventilating. He reported no prior pain, palpitations, tongue-biting or urinary incontinence. The episodes were witnessed and no abnormal movements were reported. The patient had been healthy until two months before, when he was diagnosed with diabetes mellitus by his general practitioner after routine analyses. Glycemia was controlled with diet and subcutaneous Actrapid insulin. No history of cardiac, cardiopulmonary, neurological or psychiatric disease was found and he was taking no other medication. On admission to the Emergency Department he was asymptomatic. Clinical examination was normal. The ECG showed sinus rhythm, heart rate of 70 bpm, and left bundle branch block; (LBBB). The chest X-ray was normal. As some medical features suggested a cardiac etiology (post-exercise, LBBB) and others indicated a neurally-mediated reflex syndrome or even situational syncope (after urination), a diagnostic strategy to exclude cardiac cause was adopted, including echocardiogram, and 24-hour ECG monitoring and stress test. The echocardiogram was normal. During Holter monitoring, he reported a syncopal event, in supine position, immediately after urination, and a 50-second period of cardiac arrest with persistent P waves--P-wave asystole--was recorded. Cardiac bradyarrhythmia was thus established as the cause of the syncope and a permanent pacemaker was implanted, with no recurrence of symptoms. This example of an unusually long-lasting cardiac arrest with spontaneous recovery illustrates the non-specific nature of clinical features and how difficult it is to diagnose syncope in an Emergency Department setting. The authors briefly review the topic according to recent guidelines.

Algorithms↗

PubMed2005

Accessing gelling ability of vegetable proteins using rheological and fluorescence techniques.

This work aims to present a comprehensive study about the macroscopic characteristics of globular vegetable proteins, in terms of their gelling ability, by understanding their molecular behaviour, when submitted to a thermal gelling process. The gels of soy, pea and lupin proteins were characterized by rheological techniques. Gelation kinetics, mechanical spectra, as well as the texture of these gels were analyzed and compared. Additionally, capillary viscometry, steady-state fluorescence and fluorescence anisotropy were used to monitor the structural changes induced by the thermal denaturation, which constitutes the main condition for the formation of a gel structure. Based on these techniques it was possible to establish a relationship between the gelling ability of each protein isolate and their structural resistance to thermal unfolding, enabling us to explain the weakest and the strongest gelling ability observed for lupin and soy proteins isolates, respectively.

Anisotropy↗