The O-methylated derivative of L-DOPA, 3-O-methyl-L-DOPA, fails to inhibit neuronal and non-neuronal aromatic L-amino acid decarboxylase

The present study examined whether the O-methylated derivative of L-DOPA, 3-O-methyl-L-DOPA (3-OM-L-DOPA), inhibits neuronal (brain) and non-neuronal (liver and kidney) aromatic L-amino acid decarboxylase (AADC) activity. The incubation of brain, liver and kidney homogenates with 3-OM-L-DOPA (5 mM) did not result in the formation of 3-methoxytyramine, the compound expected to result from the decarboxylation of 3-OM-L-DOPA. Incubation of tissue homogenates with L-DOPA resulted in a concentration-dependent formation of dopamine, revealing K(m) values (in mM) of similar magnitude for brain (0.8), liver (1.6) and kidney (1.0). Both benserazide and L-5-hydroxytryptophan (L-5-HTP) were found to produce concentration dependent decreases in AADC activity with K(i) values in the microM range. By contrast, 3-OM-L95% reduction) in liver and kidney AADC activity accompanied by a marked decrease (49% reduction) in brain AADC activity. By contrast, the administration of 30 mg/kg (p.o.) 3-OM-L-DOPA, which generates levels in brain, liver and kidney six-fold those in L-DOPA-treated rats, was found to change neither neuronal nor non-neuronal AADC activity. In conclusion, 3-OM-L-DOPA fails to interact with neuronal and non-neuronal AADC, either as substrate or inhibitor.     

Clustering of modifiable cardiovascular risk factors in adults living in Salvador (BA), Brazil]

OBJECTIVE: To estimate the frequency of modifiable cardiovascular risk factors, with and without inclusion of arterial hypertension, occurring simultaneously in a racially-mixed population. METHOD: A cross-sectional study was carried out with 1,298 adults aged > or = 20 years in the city of Salvador, Brazil, in 2000. Eight modifiable cardiovascular risk factors were assessed, in any combination: total cholesterol > or = 240 mg/dL; high density-lipoprotein cholesterol (HDL-c) < 40 mg/dL; triglycerides > or = 200 mg/dL; glycemia > or = 126 mg/dL + well-controlled diabetes; body mass index > or = 25 kg/m2, waist > or = 102 cm for males and > or = 88 cm for females, smoking and alcoholism. The results were stratified according to the number of simultaneous risk factors (zero to five or more and two or more risk factors). The data were analyzed in terms of estimated proportions and 95% confidence intervals (95%CI), with and without the inclusion of arterial hypertension (VI Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure [JNC-VI], United States of America), ratio of proportions and chi-square for proportions as a measure of association. RESULTS: Among men (41.4% of participants), 7.5% (95%CI: 2.5 to 9.7) did not present risk factors; 68.8% (95%CI: 65.0 to 72.8) presented two or more risk factors, not including hypertension. After inclusion of hypertension, 73.4% (95%CI: 69.7 to 77.1) presented two or more risk factors. Among women, 11.6% did not present risk factors. The presence of two or more risk factors, not including hypertension, was observed in 67.7% (95%CI: 64.8 to 71.4). After inclusion of hypertension, 71.7% (95%CI: 68.5 to 74.9) of the women presented two or more risk factors. Significant differences were observed for the presence of two or more risk factors in men with not more than 4 years of schooling vs. 5 to less than 11 years of schooling (P < 0.05); in women with not more than 4 years of schooling vs. 5 to less than 11 years of schooling; in women with not more than 4 years of schooling vs. 11 or more years of schooling (P < 0.01); and in black vs. white women (P < 0.01). CONCLUSIONS: The high proportion of clustering cardiovascular risk factors in Salvador, with or without hypertension, especially in the population with little schooling and in black individuals, suggests the need for broad social strategies to reduce social inequality, promote health, and facilitate the treatment of cardiovascular risk factors.     

The usefulness of ovarian volume, antral follicle count and age as predictors of menopausal status.

OBJECTIVE: To compare the accuracy of ovarian volume, antral follicle count and age in predicting menopausal status in healthy women. METHODS: The cross-sectional study was set in the Gynecology Division at the Leonor Mendes de Barros Maternity Hospital, S?o Paulo, Brazil. The subjects of this study were premenopausal (n = 121) and postmenopausal (n = 71) healthy women aged between 40 and 55 years. They were submitted to a medical interview and transvaginal ultrasound examination. The ovarian volume (cm3), antral follicle count and chronological age were recorded in both groups and the accuracies of these parameters in predicting menopausal status were compared. RESULTS: Premenopausal women presented larger ovaries than postmenopausal women (p < 0.01). Premenopausal women had a higher number of antral follicles than postmenopausal women (p < 0.01). The receiver operating characteristic curves showed that ovarian volume, age and antral follicle count had similar sensitivities and specificities in predicting menopausal status. The best cut-off points were observed when ovarian volume was <4 cm3, age was > or =48 years and antral follicle count was < or = two follicles. CONCLUSIONS: Ovarian volume, antral follicle count and chronological age are all individually predictive of menopausal status, with similar accuracies.     

Clinical improvement in patients with orthostatic intolerance after treatment with bisoprolol and fludrocortisone

Orthostatic intolerance is the development of disabling symptoms upon assuming an upright posture that are relieved partially by resuming the supine position. Postural tachycardia syndrome (POTS) is an orthostatic intolerance syndrome characterized by palpitations because of excessive orthostatic sinus tachycardia, lightheadedness, tremor, and near-syncope. Patients usually undergo extensive medical, cardiac, endocrine, neurologic, and psychiatric evaluation, which usually fails to identify a specific abnormality. The authors investigated the autonomic and hemodynamic profile of patients with POTS and the effectiveness of bisoprolol and fludrocortisone. The authors evaluated 11 female patients with POTS before and after medical treatment with a cardioselective bisoprolol -blocker or fludrocortisone, or both, and 11 age-matched control patients. Variability of heart rate and systolic blood pressure was assessed by fast Fourier transform, and spontaneous baroreceptor gain was assessed by use of the temporal sequences slope and index. Modelflow was used to quantify hemodynamics. Symptoms in all patients improved greatly after medication. The autonomic and hemodynamic impairment observed in patients with POTS, particularly after orthostatic stress, is treated effectively with bisoprolol or fludrocortisone or both. These results need further confirmation in a controlled double-blind study. Proper medical treatment improves dramatically the clinical and autonomic-hemodynamic disturbances observed in patients with POTS. The data support the hypothesis that POTS is the result of a hyperadrenergic activation or hypovolemia during orthostasis.     

Permeabilisation and solubilisation of soybean phosphatidylcholine bilayer vesicles, as membrane models, by polysorbate, Tween 80.

To understand better the wide-spread pharmaceutical use of non-ionic surfactant Tween 80 (TW), the colloidal properties of the surfactant alone and in combinations with the common phospholipid, phosphatidylcholine (PC), were studied. Static and dynamic light scattering revealed that TW solubilises PC at TW/PC approximately 2.75/1 mol/mol and that TW micelle disintegration occurs on time-scale of 2.5 min, independent of amphipath concentration. This is up to nearly 300-times faster than the TW caused dissolution of PC containing unilamellar vesicles. The apparent dissolution time of TW/PC mixed aggregates, in contrast, decelerates from >700 min to <5 min upon increasing starting total amphipath concentration, with thermal activation energy > or =24 (< or =80) kJ mol(-1). The aggregate dissolution rate in highly concentrated TW/PC suspensions reflects the dissolved polysorbate-aggregate exchange rate (approximately 6.7 x 10(-3)s(-1)) rather than TW flip-flop rate across a bilayer (>0.2 min(-1)). PC solubilisation proceeds linearly with the square-root of time, and is kinetically governed by the speed of surfactant diffusion through the bulk (D approximately 2.8 x 10(-11)m2 s(-1)). Creation of small Tween-phosphatidylcholine mixed micelles is typically preceded by pre-solubilisation structures, first in the form of deformable, strongly fluctuating, bilayer vesicles and then of elongated, presumably thread-like, mixed micelles. TW/PC mixed micelles become smaller with growing surfactant/lipid molar ratio, whereas TW/PC mixed vesicles become more and more leaky with increasing surfactant concentration. Our results highlight the molecular and kinetic aspects of polysorbate-membrane interactions and provide a rationale for the popularity of Tween surfactants in pharmaceutical products: such surfactants can solubilise fatty molecules and bilayer membranes but need quite a long time for this, which is available in pharmaceutical preparations but normally not in vivo; this makes Tweens relatively efficient and safe. Furthermore, our data could help design better ultra-deformable mixed lipid-surfactant vesicles for the non-invasive transdermal drug delivery across the skin.     

Most cited papers in Toxicon.

Citation of a published work is one of the parameters considered in the analysis of relevance and importance of scientific contributions. In 2002, for the first time the Impact Factor of Toxicon has risen above 2.0, placing it at the 17th position among 76 journals in the 'toxicology' field. The aim of this article was to identify the most cited articles in Toxicon, that have contributed to the steady increase of its Impact Factor. The number of citations, complete reference and type of all documents appearing in Toxicon in the period 1963-2003 were retrieved from the ISI Web-of-Science homepage. The documents retrieved were sorted by the number of citations received. A 'citation index', defined as the number of citations divided by the number of years since publication, was calculated for each document. It was clearly seen that reviews in Toxicon received 4.4-fold more citations than articles. Unexpectedly, it was found that recent papers were proportionally more cited than old ones. A decrease in the proportion of papers dealing on 'snake*' through out the period and the broadened range of subjects of the most cited papers recently published in Toxicon reflects an increased 'visibility' in other fields of toxinology. Research on plant toxins gained its own space in Toxicon with newer publications showing high citation indexes. It can be postulated that these facts helped to increase Toxicon's Impact Factor from 1.248 in 1999 to 2.003 in 2002. With the increased number of issues in Toxicon as well as publications of subject-dedicated volumes containing mostly reviews, the Impact Factor of Toxicon is expected to keep rising in the near future.     

The effect of cholate on solubilisation and permeability of simple and protein-loaded phosphatidylcholine/sodium cholate mixed aggregates designed to mediate transdermal delivery of macromolecules.

Carriers for non-invasive administration of biologically important antioxidant enzymes Cu,Zn-superoxide dismutase (SOD) and catalase (CAT) were developed. Solubilisation and permeabilities of various soybean phosphatidylcholine/sodium cholate (SPC/NaChol) mixtures, mainly in the form of lipid bilayers, focussing on system properties relevant for non-invasive enzyme delivery were investigated in this work. Static and dynamic light scattering measurements gave information on the behaviour of the systems containing up to 40 mM NaChol and 30.6-1.2 mM SPC in the final suspension. The average size of such mixed aggregates was in the 100-200 nm range. Suspension turbidity decreased by 50% upon increasing nominal molar detergent/lipid ratio to NaChol/SPC = 7 and 1.25, in case of SPC = 1.2 and 19.6 mM, respectively. The effective NaChol/SPC molar ratio in bilayers saturated with the detergent was found to be: R(e)(sat) = 0.70 +/- 0.01; bilayer solubilisation point corresponded to R(e)(sol) = 0.97 +/- 0.02, independently of enzyme loading. Vesicles became very permeable to SOD when membrane bound NaChol concentration exceeded 13.7 mM, in case of total starting lipid concentration of 138 mM diluted to SPC = 19.6 mM. Specifically, we measured a 50% loss of SOD from the vesicles with an aggregate-associated molar detergent ratio NaChol/SPC approximately 0.7, which is near the saturation but well below the solubilisation limit. Calcein efflux from such vesicles was compared with SPC/NaChol/SOD mixed aggregates. Our results should contribute to the future design of vesicle mediated transdermal delivery of antioxidant enzymes.     

Effect of Brazilian green propolis on the production of reactive oxygen species by stimulated neutrophils

The activity of a crude ethanol extract of green propolis and its fractions obtained by partition with hexane, chloroform and n-butanol was assessed on luminol- and lucigenin- enhanced chemiluminescence (CL) produced by rabbit neutrophils (PMNs) stimulated with particles of serum-opsonized zymosan (OZ). The total production of reactive oxygen species (ROS) by PMNs was measured by the luminol-enhanced CL (LumCL) assay and the production of the superoxide anion (O2*-) by the lucigenin-enhanced CL (LucCL) assay. All evaluated propolis samples had inhibitory effect on the LumCL and LucCL, which was concentration dependent. The n-butanol and chloroform fractions displayed the highest inhibitory effect on the LumCL produced by PMNs stimulated with OZ, in comparison with both the ethanol extract and the hexane fraction. Besides, the hexane fraction was the one which presented the highest effect for the LucCL assay. Some isolated compounds from both n-butanol and chloroform fractions were also assessed, including kaempferide, isosakuranetin, aromadendrine-4'-methyl-ether and 3-prenyl-p-coumaric acid. Kaempferide presented the highest inhibitory effect on the LumCL in comparison with the other compounds. Moreover, under the conditions assessed, the studied green propolis samples and isolated compounds were not toxic to the rabbit PMNs.     

Desempenho Diagnóstico da Angiotomografia Computadorizada e da Avaliação Seriada de Troponina Cardíaca Sensível em Pacientes com Dor Torácica e Risco Intermediário para Eventos Cardiovasculares

BackgroundCoronary tomography angiography (CTA) has been mainly used for chest pain evaluation in low-risk patients, and few data exist regarding patients at intermediate risk.ObjectiveTo evaluate the performance of serial measures of sensitive troponin and CTA in intermediate-risk patients.MethodsA total of 100 patients with chest pain, TIMI risk scores of 3 or 4, and negative troponin were prospectively included. All patients underwent CTA and those with coronary stenosis ≥ 50% were referred to invasive coronary angiography. Patients with coronary lesions <50% were discharged and contacted 30 days later by a telephone call to assess clinical outcomes. Outcomes were hospitalization, death, and myocardial infarction at 30 days. The comparison between methods was performed by Kappa agreement test. The performance of troponin measures and CTA for detecting significant coronary lesions and clinical outcomes was calculated. Results were considered statistically significant when p < 0.05.ResultsCoronary stenosis ≥ 50% on CTA was found in 38% of patients and significant coronary lesions on coronary angiography were found in 31 patients. Two clinical events were observed. Kappa agreement analysis showed low agreement between troponin measures and CTA in the detection of significant coronary lesions (kappa = 0.022, p = 0.78). The performance of CTA for detecting significant coronary lesions on coronary angiography or for predicting clinical events at 30 days was better than sensitive troponin measures (accuracy of 91% versus 60%).ConclusionCTA performed better than sensitive troponin measures in the detection of significant coronary disease in patients with chest pain and intermediate risk for cardiovascular events.