Membrane depolarization is the initial action of crotoxin on isolated murine skeletal muscle.

Although much is known about the pathogenesis of crotoxin-induced muscle damage, the initial site and action of the toxin is still not clear. In this study we used an electrochromic fluorescent dye, Di-4-ANEPPS, to measure the changes in membrane potential of isolated murine omohyoid muscle to determine if depolarization could be one of the initial effects of crotoxin. Omohyoid isolates were pre-loaded with 1 microM Di-4-ANEPPS, exposed to various crotoxin treatments, and the change in fluorescence was recorded using either a dual-wavelength spectrofluorometer or digital imaging. Spectrofluorometry indicated that crotoxin depolarized isolated omohyoid muscles within 4 min as indicated by an increase in fluorescence to 122% of control values. Crotoxin also induced depolarization of extensor digitorum longus and soleus muscles as indicated by an increase in fluorescence of 140 and 110% of the control, respectively. Fluorescent images obtained from omohyoid muscle preparations exposed to crotoxin and Di-4-ANEPPS revealed localized areas of increased fluorescence, muscle contractions, derangement of myofibrils, and differing sensitivity to crotoxin of different muscle cells. Light microscopy results confirmed this variable disruption of muscle cell integrity and differing sensitivity to crotoxin. An increase in creatine kinase release rates confirmed damage to the plasma membrane. We conclude that plasma membrane depolarization is most likely the earliest indicator of cell damage from crotoxin and is quickly followed by hypercontraction of myofilaments, disruption of the plasma membrane, release of creatine kinase and necrosis.     

Is there a risk of human poisoning by azaspiracids from shellfish harvested at the Portuguese coast?

Azaspiracid poisoning (AZP), the most recently discovered human gastrointestinal illness resulting from consumption of contaminated shellfish, so far has been found in coastal areas of northern Europe. This is the first report of a survey carried out for contamination of shellfish harvested in costal areas of Portugal for the presence of azaspiracids. The study design covered the commercial species usually more contaminated by toxins from dinoflagellates (blue mussel, common cockle, donax clam) in coastal areas representative of the NW, SW and south coasts. A method based on liquid chromatography–mass spectrometry was setup for the first time for this purpose. No azaspiracids were found on 300 samples tested between 2002 and 2003. On at least three samples a peak with a retention time matching that of AZA2 was found, never surpassing one tenth of the current EU limit. Unambiguous identification of any known AZA did not occur yet. The risk for human outbreaks of AZP seems to be very low, comparatively with amnesic shellfish poisoning (ASP), where levels close to the allowance level are found sparsely, or to diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP), where high levels and registered human outbreaks have been found in recent years.     

Challenges and rewards of research in marine natural products chemistry in Brazil

Brazil is blessed with a great biodiversity, which constitutes one of the most important sources of biologically active compounds, even if it has been largely underexplored. As is the case of the Amazon and Atlantic rainforests, the Brazilian marine fauna remains practically unexplored in the search for new biologically active natural products. Considering that marine organisms have been shown to be one of the most promising sources of new bioactive compounds for the treatment of different human diseases, the 8000 km of the Brazilian coastline represents a great potential for finding new pharmacologically active secondary metabolites. This review presents the status of marine natural products chemistry in Brazil, including results reported by different research groups with emphasis on the isolation, structure elucidation, and evaluation of biological activities of natural products isolated from sponges, ascidians, octocorals, and Opistobranch mollusks. A brief overview of the first Brazilian program on the isolation of marine bacteria and fungi, directed toward the production of biologically active compounds, is also discussed. The current multidisciplinary collaborative program under development at the Universidade de S?o Paulo proposes to establish a new paradigm toward the management of the Brazilian marine biodiversity, integrating research on the species diversity, ecology, taxonomy, and biogeography of marine invertebrates and microorganisms. This program also includes a broad screening program of Brazilian marine bioresources, to search for active compounds that may be of interest for the development of new drug leads.     

Evidence of anti-inflammatory effects of Passiflora edulis in an inflammation model

The popular medicine Passiflora edulis has been used as a sedative, tranquilizer, against cutaneous inflammatory diseases and intermittent fever. Most of the pharmacological investigations of Passiflora edulis have been addressed to its Central Nervous System activities, such as anxiolytic, anticonvulsant and sedative actions. Otherwise, there are few reports about the anti-inflammatory activity of the Passiflora species. The aim of this study was to investigate the mechanism of the anti-inflammatory effect of aqueous lyophilized extract obtained from leaves of Passiflora edulis var. flavicarpa Degener (Passifloraceae) in the mouse model of pleurisy induced by carrageenan (Cg), bradykinin, histamine or substance P, observing the effects upon leucocytes migration, myeloperoxidase (MPO), nitric oxide (NO) concentrations and tumor necrosis factor-alpha (TNFalpha) and interleukin-1 beta (IL-1beta) levels. RESULTS: Passiflora edulis (250mg/kg) administered by intraperitoneal route (i.p.) inhibited the leukocyte, neutrophils, myeloperoxidase, nitric oxide, TNFalpha and IL-1beta levels (P<0.01) in the pleurisy induced by carrageenan. Passiflora edulis (250-500mg/kg, i.p.) also inhibited total and differential leukocytes in the pleurisy induced by bradykinin, histamine or substance P (P<0.05). CONCLUSION: Several mechanisms, including the inhibition of pro-inflammatory cytokines (TNFalpha, IL-1beta), enzyme (myeloperoxidase) and mediators (bradykinin, histamine, substance P, nitric oxide) release and/or action, appear to account for Passiflora edulis's actions.     

Comparação entre os Efeitos da Ingestão de Sal do Himalaia e de Sal Comum sobre os Valores de Sódio Urinário e Pressão Arterial em Indivíduos Hipertensos

Background The Himalayan salt (HS) has become a popular alternative for the traditional table salt (TS) due to its health benefit claims, particularly for individuals with arterial hypertension. However, despite the increase in HS consumption, there is still a lack of clinical evidence to support a recommendation for its consumption by health professionals.Objective This cross-over study aimed to compare the impact of HS and TS intake on systolic blood pressure (SBP) and diastolic blood pressure (DBP), and urinary sodium concentration in individuals with arterial hypertension.Methods This study recruited 17 female patients with arterial hypertension who ate out no more than once a week. Participants were randomized into two groups, to receive and consume either HS or TS. Before and after each intervention, participants had their blood pressure measured and urine collected for mineral analysis. A p-value < 0.05 was considered statistically significant.Results There were no statistically significant differences before and after the HS intervention for DBP (70mmHg vs. 68.5mmHg; p=0.977), SBP (118.5 mmHg vs. 117.5 mmHg; p= 0.932) and sodium urinary concentration (151 mEq/24h vs. 159 mEq/24; p=0.875). Moreover, the between-group analysis showed no significant differences after the intervention regarding SBP (117mmHg vs 119 mmHg; p=0.908), DBP (68.5 mmHg vs. 71mmHg; p= 0,645) or sodium urinary concentration (159 mEq/24h vs. 155 mEq/24h; p=0.734).Conclusion This study suggests that there are no significant differences on the impact of HS consumption compared to TS on blood pressure and sodium urinary concentration in individuals with arterial hypertension.     

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.     

Effects of Crotalus durissus collilineatus venom in the isolated rat kidney.

Ophidian accidents caused by the subspecies Crotalus durissus are responsible for high morbity and mortality rates. Acute renal failure is a common complication observed in these accidents. The aim of the present study was to investigate the renal effects promoted by the venom of C. d. collilineatus and its fractions, crotoxin and phospholipase A2. C. d. collilineatus (Cdc; 30 microg mL(-1)), crotoxin (CTX; 10 microg mL(-1)) and phospholipase A2 (PLA2; 10 microg mL(-1)) were tested in isolated rat kidney. The first 30 min of each experiment were used as an internal control and Cdc or its fractions, CTX and PLA2 were added to the system after this period. All experiments lasted 120 min. The venom of Cdc decreased perfusion pressure (PP; control120 = 110.3 +/- 3.69 mmHg; Cdc120 = 96.7+/-8.1 mmHg), renal vascular resistance (RVR; control120 = 6.42+/-0.78 mmHg mL g(-1) min(-1); Cdc120 = 4.8+/-0.56 mmHg/mL g(-1) min(-1)), urinary flow (UF; control120 = 0.19+/-0.03 mL g(-1) min(-1); Cdc120 = 0.12 +/- 0.01 mL g(-1) min(-1)), and glomerular filtration rate (GFR; control120 = 0.79 +/- 0.07 mL g(-1) min(-1); Cdc120 = 0.53 +/- 0.09 mL g(-1) min(-1)), but had no effect on the percent of sodium tubular transport (%TNa+), percent of chloride tubular transport (%TK+) and percent of potassium tubular transport (%TCl-). CTX and PLA2 reduced the GFR, while UF, PP and RVR remained stable during the full 120 min of perfusion. Crotoxin administration also diminished the %TK+ (control120 = 69.94 +/- 6.49; CTX120 = 33.28 +/- 4.78) and %TCl- (control120 = 79.53 +/- 2.67; CTX120 = 64.62 +/- 6.93). PLA2 reduced the %TK+, but exerted no effect on the %TNa+ or on that of TCl-. In conclusion, the C. d. collilineatus venom altered the renal functional parameters evaluated. We suggest that crotoxin and phospholipase A2 were involved in this process, since the renal effects observed would be due to the synergistic action of the components of the venom.     

The opposing effects of the flavonoids isoquercitrin and sissotrin, isolated from Pterospartum tridentatum, on oral glucose tolerance in rats

The effect of an aqueous extract of Pterospartum tridentatum on the blood glucose levels of normal Wistar rats was investigated in a situation of oral glucose challenge. The extract at 300 mg/kg showed an antihyperglycaemic effect in the first 30 min after glucose challenge but then the blood glucose levels rose above those of the control group, indicating the presence of compounds with different effects on glucose tolerance. Nine compounds of isoflavone and flavonol skeletons were identified in the extract by HPLC-ESI-MS(n), four of them being identified for the first time in this species. The isoflavone sissotrin and the flavonol derivative, isoquercitrin, were selected for the oral glucose tolerance test. Isoquercitrin (100 mg/kg) showed time-dependent antihyperglycaemic activity by delaying the post-oral glucose load glycaemic peak at 30 min, as did the sodium-dependent glucose transporter inhibitor phloridzin (100 mg/kg). In contrast, sissotrin (100 mg/kg) showed an opposite effect, impairing glucose tolerance. In conclusion, these preliminary results indicate that the effect of the extract on blood glucose may be either antihyperglycaemic or hyperglycaemic. Additionally, as far as is known, these are the first in vivo results on the acute antihyperglycaemic potential of isoquercitrin.