The First Brazilian Cardiovascular Registry of Atrial Fibrillation: Primary Results of the RECALL Study

BACKGROUND

It is estimated that atrial fibrillation (AF) affects approximately 1.5 million people in Brazil; however, epidemiological data are limited. We sought to evaluate the characteristics, treatment patterns, and clinical outcomes in patients with AF in Brazil by creating the first nationwide prospective registry.

METHODS

RECALL was a multicenter, prospective registry that included and followed for 1 year 4,585 patients with AF at 89 sites across Brazil from April 2012 to August 2019. Patient characteristics, concomitant medication use, and clinical outcomes were analyzed using descriptive statistics and multivariable models.

RESULTS

Of 4,585 patients enrolled, the median age was 70 (61, 78) years, 46% were women, and 53.8% had permanent AF. Only 4.4% of patients had a history of previous AF ablation and 25.2% had a previous cardioversion. The mean (SD) CHA2DS2-VASc score was 3.2 (1.6); median HAS-BLED score was 2 (2, 3). At baseline, 22% were not on anticoagulants. Of those taking anticoagulants, 62.6% were taking vitamin K antagonists and 37.4% were taking direct oral anticoagulants. The primary reasons for not using an oral anticoagulant were physician judgment (24.6%) and difficulty in controlling (14.7%) or performing (9.9%) INR. Mean (SD) TTR for the study period was 49.5% (27.5). During follow-up, the use of anticoagulants and INR in the therapeutic range increased to 87.1% and 59.1%, respectively. The rates/100 patient-years of death, hospitalization due to AF, AF ablation, cardioversion, stroke, systemic embolism, and major bleeding were 5.76 (5.12-6.47), 15.8 (14.6-17.0), 5.0 (4.4-5.7), 1.8 (1.4-2.2), 2.77 (2.32-3.32), 1.01 (0.75-1.36), and 2.21 (1.81-2.70). Older age, permanent AF, New York Heart Association class III/IV, chronic kidney disease, peripheral arterial disease, stroke, chronic obstructive pulmonary disease, and dementia were independently associated with increased mortality while the use of anticoagulant was associated with lower risk of death.

CONCLUSIONS

RECALL represents the largest prospective registry of patients with AF in Latin America. Our findings highlight important gaps in treatment, which can inform clinical practice and guide future interventions to improve the care of these patients.

Factors that influence trace element levels in blood and feathers of Pygoscelis penguins from South Shetland Islands, Antarctica

Contaminant levels are lower in Antarctica than elsewhere in the world because of its low anthropogenic activities. However, the northern region of the Antarctic Peninsula, is close to South America and experiences the greatest anthropogenic pressure in Antarctica. Here, we investigated, in two Antarctic Peninsula islands, intra and interspecific factors that influence the concentrations of 17 trace elements (TEs) in blood and feathers of three penguin species breeding sympatrically in relation to their trophic ecology assessed via a stable isotopic approach (C, N and S). Geographical location, foraging zone (δ¹³C and δ³⁴S) and diet influences the interspecific difference, and sex and maturity stage diet influence the intraspecific difference of Pygoscelis penguins. Penguins from Livingston showed higher values (mean, ng. g^-1, dry weight - dw) of Zn (103), Mn (0.3), and Fe (95) than those from King George Island (Zn: 80, Mn: 1.9, and Fe: 11). Gender-related differences were observed, as males showed significantly higher values (mean, ng. g^-1, dw) of Rb (3.4) and δ¹⁵N in blood of gentoo, and Ca (1344) in Adélie feathers. Chicks of gentoo and Adélie presented higher Zn, Mg, Ca, and Sr and lower ¹³C values in blood than adults. The highest concentrations (mean, ng. g^-1, dw) of Cd (0.2) and Cu (26), and the lowest δ¹⁵N values were found in chinstrap. Geographical, intraspecific (i.e., ontogenetic and gender-related) and interspecific differences in feeding seemed to have influenced TE and stable isotope values in these animals. The TE bioaccumulation by penguins may have also been influenced by natural enrichment in environmental levels of these elements, which seems to be the case for Fe, Zn, and Mn. However, the high level of some of the TEs (Mn, Cd, and Cr) may reflect the increase of local and global human activities.

Atorvastatin for high-risk statin-naïve patients undergoing noncardiac surgery: The Lowering the Risk of Operative Complications Using Atorvastatin Loading Dose (LOAD) randomized trial

Preliminary evidence suggests that statins may prevent major perioperative vascular complications.

METHODS

We randomized 648 statin-naïve patients who were scheduled for noncardiac surgery and were at risk for a major vascular complication. Patients were randomized to a loading dose of atorvastatin or placebo (80 mg anytime within 18hours before surgery), followed by a maintenance dose of 40 mg (or placebo), started at least 12hours after the surgery, and then 40 mg/d (or placebo) for 7days. The primary outcome was a composite of all-cause mortality, nonfatal myocardial injury after noncardiac surgery, and stroke at 30days.

RESULTS

The primary outcome was observed in 54 (16.6%) of 326 patients in the atorvastatin group and 59 (18.7%) of 316 patients in the placebo group (hazard ratio [HR] 0.87, 95% CI 0.60-1.26, P=.46). No significant effect was observed on the 30-day secondary outcomes of all-cause mortality (4.3% vs 4.1%, respectively; HR 1.14, 95% CI 0.53-2.47, P=.74), nonfatal myocardial infarction (3.4% vs 4.4%, respectively; HR 0.76, 95% CI 0.35-1.68, P=.50), myocardial injury after noncardiac surgery (13.2% vs 16.5%; HR 0.79, 95% CI 0.53-1.19, P=.26), and stroke (0.9% vs 0%, P=.25).

CONCLUSION

In contrast to the prior observational and trial data, the LOAD trial has neutral results and did not demonstrate a reduction in major cardiovascular complications after a short-term perioperative course of statin in statin-naïve patients undergoing noncardiac surgery. We demonstrated, however, that a large multicenter blinded perioperative statin trial for high-risk statin-naïve patients is feasible and should be done to definitely establish the efficacy and safety of statin in this patient population.

Bone Morphogenetic Protein-6 (BMP-6) Stimulates the Antrum Formation by the Regulation of its Signalling Pathway in Caprine Pre-antral Follicles Cultured In Vitro

BMP-6 has been found to be important to ovarian cells and oocyte, as well as to uterus. Thus, this study investigated the effect of bone morphogenetic protein (BMP-6) and recombinant follicle-stimulating hormone (rFSH) alone or in combination on the in vitro culture (IVC) of isolated caprine secondary follicles (Experiment 1) and the mRNA levels for BMP receptors/Smad signalling pathway (BMPR1A, BMPR2, SMAD1, SMAD4, SMAD5, SMAD6, SMAD7 and SMAD8) in vivo and in vitro using BMP-6 (Experiment 2). Secondary follicles were cultured in αMEM(+) alone (control medium) or supplemented with BMP-6 at 1 or 10 ng/ml and rFSH alone or the combination of both BMP-6 concentrations and rFSH. The results from Experiment 1 showed that the antrum formation rate was higher in the BMP-6 at 1 ng/ml (p < 0.05) than in MEM. In Experiment 2, the mRNA expression for BMPR2, SMAD1, SMAD5 and SMAD6 was detected in non-cultured control and after in vitro culture (MEM and 1 ng/ml BMP-6); while the expression of SMAD7 and SMAD8 mRNA was only detected after IVC, SMAD4 was only detected in the BMP-6 at 1 ng/ml treatment. In conclusion, the low BMP-6 concentration positively influenced antrum formation and ensured normal mRNA expression for BMP receptor and Smads after IVC of caprine secondary follicles.

Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters.

Presence of growth hormone receptor (GH-R) mRNA and protein in goat ovarian follicles and improvement of in vitro preantral follicle survival and development with GH

This study aimed to demonstrate the expression of growth hormone receptor (GH-R) mRNA and protein in goat ovarian follicles in order to investigate the effects of GH on the survival and development of preantral follicles. The ovaries were processed for the isolation of follicles to study GH-R mRNA expression or to localization of GH-R by immunohistochemical analysis. Pieces of ovarian cortex were cultured for 7 days in minimum essential medium(+) (MEM(+)) in the presence or absence of GH at different concentrations (1, 10, 50, 100, and 200 ng/mL). High expression levels of GH-R mRNA were observed in granulosa/theca cells from large antral follicles. However, preantral follicles do not express mRNA for GH-R. Immunohistochemistry demonstrated that the GH-R protein was expressed in the oocytes/granulosa cells of antral follicles, but any protein expression was observed in preantral follicles. The highest (P < 0.05) rate of normal follicles and intermediate follicles was observed after 7 days in MEM(+) plus 10 ng/mL GH (70%). In conclusion, GH-R mRNA and protein are expressed in caprine antral follicles, but not in preantral follicles. Moreover, GH maintains the survival of goat preantral follicles and promotes the development of primordial follicles.

Effects of short-term administration of estradiol on reperfusion arrhythmias in rats of different ages

Little is known about age-related differences in short-term effects of estradiol on ischemia-reperfusion (I/R) insults. The present study was designed to evaluate the effects of short-term treatment with estradiol on reperfusion arrhythmias in isolated hearts of 6-7-week-old and 12-14-month-old female rats. Wistar rats were sham-operated, ovariectomized and treated with vehicle or ovariectomized and treated with 17β-estradiol (E₂; 5 µg·100 g⁻¹·day⁻¹) for 4 days. Hearts were perfused by the Langendorff technique. Reperfusion arrhythmias, i.e., ventricular tachycardia and/or ventricular fibrillation, were induced by 15 min of left coronary artery ligation and 30 min of reperfusion. The duration and incidence of I/R arrhythmias were significantly higher in young rats compared to middle-aged rats (arrhythmia severity index: 9.4 ± 1.0 vs 3.0 ± 0.3 arbitrary units, respectively, P < 0.05). In addition, middle-aged rats showed lower heart rate, systolic tension and coronary flow. Four-day E₂ treatment caused an increase in uterine weight. Although E₂ administration had no significant effect on the duration of I/R arrhythmias in middle-aged rats, it induced a marked reduction in the rhythm disturbances of young rats accompanied by a decrease in heart rate of isolated hearts. Also, this reduction was associated with an increase in QT interval. No significant changes were observed in the QT interval of middle-aged E₂-treated rats. These data demonstrate that short-term estradiol treatment protects against I/R arrhythmias in hearts of young female rats. The anti-arrhythmogenic effect of estradiol might be related to a lengthening of the QT interval.

Anticonvulsant and antiarrhythmic effects of nifedipine in rats prone to audiogenic seizures

Calcium ion participates in the regulation of neural transmission and the presynaptic release of neurotransmitters. It is also involved in epileptic events, cardiac arrhythmias and abnormal conduction of stimuli. The purpose of the present study was to evaluate the effects of nifedipine, a calcium channel blocker, on epileptic seizures and on reperfusion arrhythmias in rats prone to audiogenic epileptic seizures (Wistar audiogenic rats, WAR) and in normal Wistar rats (N = 6/group). The seizure severity index was applied after an intraperitoneal injection of 20 or 40 mg/kg nifedipine (N20 and N40 groups, respectively). The Langendorff technique was used to analyze cardiac function, as well as the incidence and severity of the reperfusion arrhythmias after ligature and release of the left coronary artery in rats treated or not with nifedipine. We found that nifedipine treatment decreased seizure severity (0.94 ± 0.02 for WAR; 0.70 ± 0.10 for WAR + N20; 0.47 ± 0.08 for WAR + N40) and increased the latent period (13 ± 2 s for WAR; 35 ± 10 s for WAR + N20; 48 ± 7 s for WAR + N40) for the development of seizures in WAR. Furthermore, the incidence and severity of the reperfusion arrhythmias were lower in WAR and normal Wistar rats injected with nifedipine. In WAR, these effects were mediated, at least in part, by a decrease in heart rate. Thus, our results indicate that nifedipine may be considered to be a potential adjuvant drug for epilepsy treatment, especially in those cases associated with cardiac rhythm abnormalities.

Vascular endothelial growth factor-A(165) (VEGF-A(165)) stimulates the in vitro development and oocyte competence of goat preantral follicles

The aim of this study was to evaluate the effect of vascular endothelial growth factor-A(165) (VEGF-A(165)) on the in vitro development of goat secondary preantral follicles. Preantral follicles (≥150 μm in diameter) were isolated from the ovaries of adult mixed-breed goats and individually cultured for 18 days in αMEM in the absence (control) or presence of VEGF-A(165) at concentrations of 10 ng/ml (VEGF10) and 100 ng/ml (VEGF100). Analyses of follicular survival, diameter, antrum formation and rate of daily growth were performed every 6 days. At the end of the culture period, morphologically normal oocytes (≥110 μm in diameter) were taken for in vitro maturation (IVM). The results demonstrated that all follicles presented oocytes and granulosa cells that were morphologically normal and after labeling with calcein-AM, high rates of oocyte viability were observed in all treatments. The follicular diameter and the growth rate achieved in the presence of VEGF10 were higher than those of the control. Both treatments with VEGF-A(165) showed higher rates of oocyte recovery for IVM when compared with the control. Moreover, only the addition of VEGF-A(165) permitted oocytes grown in vitro to reach metaphase II. Thus, the addition of VEGF-A(165) to the culture medium improves the development of goat preantral follicles cultured in vitro, allowing the production of mature oocytes.

Steady-state level of insulin-like growth factor-I (IGF-I) receptor mRNA and the effect of IGF-I on the in vitro culture of caprine preantral follicles

The objectives were to quantify insulin-like growth factor receptor-1 (IGFR-1) mRNA in preantral follicles on Days 0 and 18 of in vitro culture in the presence or absence of FSH, and to evaluate the effects of IGF-I on the rate of normal follicles, antral cavity formation, and in vitro growth and maturation of caprine oocytes on Days 0, 6, 12, and 18 of culture. The expression of IGFR-1 was analyzed using real-time RT-PCR before and after follicle culture. Preantral follicles were isolated from the cortex of caprine ovaries and individually cultured for 18 d in the presence or absence of bovine IGF-I (50 or 100 ng/mL). At the end of the culture period, the oocytes were submitted to IVM. The expression of IGFR-1 mRNA in preantral follicles cultured in vitro only approached being significantly higher in follicles supplemented with FSH when compared to follicles immediately after recovery (P<0.06) and cultured without FSH (P<0.1). There was a higher (P<0.05) percentage of normal follicles on Days 6, 12, and 18 of culture in IGF-I 50 (97, 92, 67%, respectively) and IGF-I 100 (100, 90, 80%) groups versus the control (90, 64, 36%). In addition, the rate of antrum formation at 6 and 12 d of culture was higher (P<0.05) in IGF-I groups (IGF-I 50: 72 and 90% and IGF-I 100: 69 and 85%) than the control group (41 and 59%). After 18 d of culture, the percentages of grown oocytes acceptable for IVM were higher (P<0.05) in follicles cultured in the presence of IGF-I (82 vs 49%). Furthermore, follicles cultured in the presence of IGF-I 50 and IGF-I 100 had higher (P<0.05) meiotic resumption rates (63 and 66%, respectively) than the control group (11%). In conclusion, treatment with FSH tended to increase IGFR-1 mRNA expression during the in vitro culture of preantral follicles and the addition of IGF-I to the culture medium clearly improved the in vitro development of caprine preantral follicles.

Embryo production in superovulated goats treated with insulin before or after mating or by continuous propylene glycol supplementation

Seventeen adult and cyclic Moxoto goats were synchronized using 60 mg MPA vaginal sponge for 11 days and 50 mug cloprostenol, 48 h before sponge removal, and superovulated with 120 mg pFSH i.m. in decreasing doses at 12 h intervals for three consecutive days. In seven goats, 0.2 IU/kg BW/day of long acting insulin was subcutaneously injected at same time as pFSH, and in the other five goats, the same dose of insulin was injected for three consecutive days starting 24 h after mating. Finally, five goats were supplemented with an oral dose of 80 ml/goat/day of propylene glycol continuously during the experiment. The animals were flushed at 7 days after mating and the embryos were classified based on International Embryo Transfer Society criteria. Blood samples were collected every 3 days for insulin assay. Administration of insulin raised the insulin levels of the goats (p < 0.05), whereas in the group treated with propylene glycol, insulin rate was different only between FSH treatment and after mating (p < 0.05). Similar rates of recovery for total (80.05 +/- 9.78%) or transferable structures (61.03 +/- 15.13%) were obtained. Treatment was not influenced (p > 0.05) by responsiveness to superovulation, which averaged 64%. By contrast, insulin treatments were shown to increase the number of embryos considered excellent with respect to goats supplemented with propylene glycol (p < 0.05). When insulin was given before mating, a strong relationship (r = 0. 90) (p < 0.05) between number of transferable embryo and ovulations was observed in the animals. In conclusion, superovulated goats treated with low doses of exogenous insulin resulted in an enhancement in embryo quality, which was related to changes in circulating insulin concentrations.

Toxicological analysis and effectiveness of oral Kalanchoe pinnata on a human case of cutaneous leishmaniasis

Leishmaniasis is an extremely difficult disease to treat. Previously, it was shown that oral Kalanchoe pinnata (Kp) leaf extract is strongly effective against murine leishmaniasis. Here, it is shown that the serum levels of alanine-aminotransferase (ALT), aspartate-aminotransferase (AST), urea and alkaline phosphatase were unchanged in mice orally treated with supraoptimal Kp doses for 30 days, indicating the absence of chronic toxicity to the liver, heart or kidney. Additionally, evidence is presented that human leishmaniasis may also be controlled with oral Kp. A 36-year-old man with an active cutaneous leishmaniasis was orally treated with 30 g wet weight of Kp leaves/day for 14 days. During the Kp treatment, the lesion stopped growing and slightly decreased. No adverse reactions or toxicity was observed. This study reports for the first time that Kalanchoe pinnata contains substances potentially active and safe for the oral treatment of human cutaneous leishmaniasis.

Preliminary in vitro studies on the Marsypianthes chamaedrys (boia-caá) extracts at fibrinoclotting induced by snake venoms

The extract of Marsypianthes chamaedrys, a plant used against snakebites, in the present study was shown to inhibit fibrinoclotting induced by several Brazilian snake venoms or thrombin. These data indicate that this extract affected thrombin-like enzymes. In this first report we determine some features of the components present in the extract regarding the antifibrinoclotting action. Our results show that active components responsible for those effects are thermo-resistant and are concentrated in the methanolic fraction.

Angiotensin-(1-7) improves the post-ischemic function in isolated perfused rat hearts

We evaluated the effects of angiotensin-(1-7) (Ang-(1-7)) on post-ischemic function in isolated hearts from adult male Wistar rats perfused according to the Langendorff technique. Local ischemia was induced by coronary ligation for 15 min. After ischemia, hearts were reperfused for 30 min. Addition of angiotensin II (Ang II) (0.20 nM, N = 10) or Ang-(1-7) (0.22 nM, N = 10) to the Krebs-Ringer perfusion solution (KRS) before the occlusion did not modify diastolic or systolic tension, heart rate or coronary flow (basal values for Ang-(1-7)-treated hearts: 0.72 +/- 0.08 g, 10.50 +/- 0.66 g, 216 +/- 9 bpm, 5.78 +/- 0.60 ml/min, respectively). During the period of occlusion, the coronary flow, heart rate and systolic tension decreased (values for Ang-(1-7)-treated hearts: 2.83 +/- 0.24 ml/min, 186 +/- 7 bpm, 6.95 +/- 0.45 g, respectively). During reperfusion a further decrease in systolic tension was observed in control (4.95 +/- 0.60 g) and Ang II-treated hearts (4.35 +/- 0.62 g). However, in isolated hearts perfused with KRS containing Ang-(1-7) the further reduction of systolic tension during the reperfusion period was prevented (7.37 +/- 0.68 g). The effect of Ang-(1-7) on the systolic tension was blocked by the selective Ang-(1-7) antagonist A-779 (2 nM, N = 9), by the bradykinin B2 antagonist HOE 140 (100 nM, N = 10), and by indomethacin pretreatment (5 mg/kg, ip, N = 8). Pretreatment with L-NAME (30 mg/kg, ip, N = 8) did not change the effect of Ang-(1-7) on systolic tension (6.85 +/- 0.61 g). These results show that Ang-(1-7) at low concentration (0.22 nM) improves myocardial function (systolic tension) in ischemia/reperfusion through a receptor-mediated mechanism involving release of bradykinin and prostaglandins.

Angiotensin-(1-7): cardioprotective effect in myocardial ischemia/reperfusion

In this study we evaluate the effects of angiotensin-(1-7) on reperfusion arrhythmias in isolated rat hearts. Rat hearts were perfused according to Langendorff technique and maintained in heated (37+/-1 degrees C) and continuously gassed (95% O(2)/5% CO(2)) Krebs-Ringer solution at constant pressure (65 mm Hg). The electrical activity was recorded with an ECG (bipolar). Local ischemia was induced by coronary ligation for 15 minutes. After ischemia, hearts were reperfused for 30 minutes. Cardiac arrhythmias were defined as the presence of ventricular tachycardia and/or ventricular fibrillation after the ligation of the coronary artery was released. Angiotensin II (0.20 nmol/L, n=10) produced a significant enhancement of reperfusion arrhythmias. On the other hand, Ang-(1-7) presented in the perfusion solution (0.22 nmol/L, n=11) reduced incidence and duration of arrhythmias. The antiarrhythmogenic effects of Ang-(1-7) was blocked by the selective Ang-(1-7) antagonist A-779 (2 nmol/L, n=9) and by indomethacin pretreatment (5 mg/kg IP, n=8) but not by the bradykinin B(2) antagonist HOE 140 (100 nmol/L, n=10) or by L-NAME pretreatment (30 mg/kg IP, n=8). These results suggest that the antiarrhythmogenic effect of low concentrations of Ang-(1-7) is mediated by a specific receptor and that release of endogenous prostaglandins.by Ang-(1-7) contributes to the alleviation of reversible and/or irreversible ischemia-reperfusion injury.

Dogs as a favored host choice of Anopheles gambiae sensu stricto (Diptera: Culicidae) of São Tomé West Africa

The host source and human blood index (HBI) of an exophilic population of the "forest" cytoform of Anopheles gambiae Giles sensu stricto, from a peri-urban area of the island of São Tomé were assessed. Blood meals of 434 An. gambiae females from all-night indoor light-trap collections, 193 from indoor and 422 from outdoor resting collections, were determined by ELISA. Significant differences were found in the HBI estimates from insects collected indoors (0.93) and outdoors (0.27). Blood-fed insects collected resting outdoors provided the most representative sample for host determination. Dogs were the predominant hosts, followed by humans and pigs. Of all human feeds, it was estimated that 81.5% were taken inside houses. The low HBI of 0.27 for the An. gambiae population explains the low sporozoite rate and the meso-endemicity of malaria in the island.

Angiotensin-(1-7) potentiates the coronary vasodilatatory effect of bradykinin in the isolated rat heart

It has been shown that angiotensin-(1-7) (Ang-(1-7)) infusion potentiates the bradykinin (BK)-induced hypotensive response in conscious rats. The present study was conducted to identify Ang-(1-7)-BK interactions in the isolated rat heart perfused according to the Langendorff technique. Hearts were excised and perfused through the aortic stump under a constant flow with Krebs-Ringer solution and the changes in perfusion pressure and heart contractile force were recorded. Bolus injections of BK (2.5, 5, 10 and 20 ng) produced a dose-dependent hypotensive effect. Ang-(1-7) added to the perfusion solution (2 ng/ml) did not change the perfusion pressure or the contractile force but doubled the hypotensive effect of the lower doses of BK. The BK-potentiating Ang-(1-7) activity was blocked by pretreatment with indomethacin (5 mg/kg, ip) or L-NAME (30 mg/kg, ip). The Ang-(1-7) antagonist A-779 (50 ng/ml in Krebs-Ringer) completely blocked the effect of Ang-(1-7) on BK-induced vasodilation. These data suggest that the potentiation of the BK-induced vasodilation by Ang-(1-7) can be attributed to the release of nitric oxide and vasodilator prostaglandins through an Ang-(1-7) receptor-mediated mechanism.

Isolation and chemical analysis of a fatty acid fraction of Kalanchoe pinnata with a potent lymphocyte suppressive activity

Previously we demonstrated that Kalanchoe pinnata (KP) leaf extracts inhibited in vitro lymphocyte proliferation and showed in vivo immunosuppressive activity. Here we attempt to identify the immunosuppressive substances present in KP guided by the lymphoproliferative assays. From the ethanolic extract was purified a fraction (KP12SA) twenty-fold more potent to block murine lymphocyte proliferation than the crude extract. Chemical analysis by 1H- and 13C-NMR, IR and GC-MS of KP12SA (methylated sample) showed 89.3% of palmitic acid (C16), 10.7% of stearic acid (C18) and traces of arachidic (C20) and behenic acids (C22). This study provides evidence that fatty acids present in Kalanchoe pinnata may be responsible, at least in part, for its immunosuppressive effect in vivo.

Induced immunity against the mosquito Anopheles stephensi: reactivity characteristics of immune sera

This study shows the progression of immune responses in mice during five sequential immunizations with Anopheles stephensi mosquito extracts, characterized by ELISA, Western blot and immunohistochemistry. When exposed repeatedly to mosquito bites, control mice developed antibodies which reached titres of 1:10(5), reacted weakly in Western blot analysis and were localized to the salivary glands. Mice immunized with mosquito head plus salivary glands, midgut, ovary, fat body, midgut microvilli (Mv) and midgut basolateral plasma membrane (Blm), showed increased titre with each successive boost. Epitopes were shared between sera or were specific to the immunizing or heterologous extract. Anti-Mv and Blm sera recognized proteins labelled by anti-midgut serum and gave specific reactions with the midgut and head. Cross-reactivity was confirmed immunohistochemically.

Induced immunity against the mosquito Anopheles stephensi Liston (Diptera: Culicidae): effects on mosquito survival and fecundity

Mice were immunised three to five times with extracts of Anopheles stephensi heads, midguts, ovaries or fat bodies. At each immunisation the effects of feeding An. stephensi on the mice was determined, and changes in mosquito longevity and fecundity examined as the immune response developed. Although variability was common between control cages, significant and consistent reductions in mosquito longevity were observed when midguts were used as immunogens. Other extracts caused transient reductions in mortality. Fecundity was reduced significantly in mosquitoes fed upon mice immunised with each extract in at least one experiment. Mosquitoes fed upon fat-body-immunised mice showed delayed egg-laying as well as overall reduction in fecundity. The results confirm the feasibility of targeting mosquito antigens for novel vaccine development, but the "shotgun" approach used probably fails to successfully hit a suitable target antigen with any consistency. The natural variation in mosquito mortality can be countered by rigorous statistical analysis which can identify subtle effects in a very "noisy" experimental system. The midgut is the obvious target organ for anti-mosquito vaccine development and future work will focus on targeting components of this tissue for further immunisations.

Effect of angiotensin-(1-7) on reperfusion arrhythmias in isolated rat hearts

There is increasing evidence that angiotensin-(1-7)(Ang-(1-7)) is an endogenous biologically active component of the renin-angiotensin system(RAS). In the present study, we investigated the effects of Ang-(1-7) on reperfusion arrhythmias in isolated rat hearts. Isolated rat hearts were perfused with two different media, i.e., Krebs-Ringer (2.52 mM CaCl2) and low-Ca2+ Krebs-Ringer (1.12 mM CaCl2). In hearts perfused with Krebs-Ringer, Ang-(1-7) produced a concentration-dependent (27-210 nM) reduction in coronary flow (25% reduction at highest concentration), while only slight and variable changes in contraction force and heart rate were observed. Under the same conditions, angiotensin II (Ang II; 27 and 70 nM) produced a significant reduction in coronary flow (39% and 48%, respectively) associated with a significant increase in force. A decrease in heart rate was also observed. In low-Ca2+ Krebs-Ringer solution, perfusion with Ang-(1-7) or Ang II at 27 nM concentration produced similar changes in coronary flow, contraction force and heart rate. In isolated hearts perfused with normal Krebs-Ringer, Ang-(1-7) produced a significant enhancement of reperfusion arrhythmias revealed by an increase in the incidence and duration of ventricular tachycardia and ventricular fibrillation (more than 30-min duration). The facilitation of reperfusion arrhythmias by Ang-(1-7) was associated with an increase in the magnitude of the decreased force usually observed during the postischemic period. The effects of Ang-(1-7) were abolished in isolated rat hearts perfused with low-Ca2+ Krebs-Ringer. The effect of Ang II (27 nM) was similar but less pronounced than that of Ang-(1-7) at the same concentration. These results indicate that the heart is a site of action for Ang-(1-7) and suggest that this heptapeptide may be involved in the mediation of the cardiac effects of the RAS.

Metabolism of angiotensin I in isolated rat hearts. Effect of angiotensin converting enzyme inhibitors

In this study, the formation of biologically active angiotensins from angiotensin I (Ang I) in isolated rat hearts was evaluated. The role of angiotensin converting enzyme (ACE) in Ang I metabolism was also investigated. HPLC analysis of heart perfusate showed that 125I-Ang I was metabolized extensively (single passage) in the rat coronary circulation in vitro leading to the formation of the biologically active angiotensins: angiotensin II (Ang II), Ang-(2-8), Ang-(3-8) and Ang-(1-7). Ang II was the major product identified in HPLC fractions, corresponding to 7.8 +/- 0.89% of the total radioactivity recovered. A similar profile was observed when single-passage metabolism of non-isotopic Ang I was evaluated by HPLC, followed by radioimmunoassay of the eluate fractions. When 125I-Ang I was perfused in the presence of ACE inhibitors (enalaprilat, ramiprilat) in concentrations up to 130 microM, the formation of Ang II was only partially inhibited (approximately 50%). A similar tendency was observed for Ang-(2-8), Ang-(3-8) and Ang-(2-7). The formation of Ang-(1-7) and its related fragments Ang-(3-7) and Ang-(4-7) was not changed significantly by ACE inhibitors, although a slight increase in formation of these fragments was observed. No significant changes were observed for the carboxyl-terminal fragments of Ang I: Ang-(2-10), Ang-(3-10), and Ang-(4-10). The fractional metabolism of Ang I was not modified by ACE inhibition. These findings suggest that biologically active angiotensins can be formed from Ang I in the rat coronary circulation. These locally generated peptides may contribute to the actions of the renin-angiotensin system in the heart.

Effects of toxin Ts-gamma and tityustoxin purified from Tityus serrulatus scorpion venom on isolated rat atria

The effects of toxin Ts-gamma and tityustoxin purified from Tityus serrulatus scorpion venom were investigated on isolated rat atria. Rat atria were placed in an organ bath containing Krebs-Ringer solution, 30 degrees C, pH 7.4, and bubbled with a gas mixture of 95% O2 and 5% CO2. The atrial rate and contractile force were simultaneously recorded. Addition of toxin Ts-gamma to the bath (0.14 microM) evoked an initial reduction of both atrial rate and contractile force, followed by a small increase in force and a decrease in rate, and finally a long reduction of rate and force. Addition of an identical dose of Ts-gamma 30 or 60 min later did not evoke any effect. Addition of tityustoxin to the bath (0.14 microM) induced an increase of atrial rate and force. Addition of an identical dose of tityustoxin 30 min later evoked similar effects. The negative chronotropic and inotropic effects induced by Ts-gamma were abolished by tetrodotoxin (TTX, 1 microM) or atropine (1.5 microM), whereas the positive effects observed in the presence of atropine were prevented by TTX (1 microM) or alprenolol (10 microM). The negative chronotropic effect of 0.14 microM tityustoxin was only observed in the presence of physostigmine (0.3 microM). This negative effect was abolished by TTX (1 microM) or atropine (1.5 microM). The positive inotropic effect of tityustoxin was decreased by TTX (1 microM and 10 microM), but was totally prevented by guanethidine (10 microM) or alprenolol (10 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Cross-reactivity between hard tick antigens

1. The present study was carried out to determine the target cells and tissues for anti-tick immunoglobulins using an indirect immunohistochemical technique. 2. Sections in triplicate prepared from unfed ticks Rhipicephalus appendiculatus, R. evertsi and Amblyomma variegatum were used to assess the cross-reactivity of serum from guinea pigs naturally infested with these tick species or immunized against them. 3. The sections showed slight (+) to strong ( +) labelling of several structures in the tick body, e.g. salivary gland, gut lumen and malpighian tubules, depending on the serum used. 4. The immune serum resulting from the immunization of guinea pigs with an extract of unfed nymphs of R. appendiculatus ticks showed the most intense cross-reactivity with the sections examined.

Effects of anesthetics on the incidence and duration of reperfusion arrhythmias in isolated rat heart

The present study was carried out to evaluate the effect of anesthetics on reperfusion arrhythmias. Male Wistar rats (200-300 g) were injected ip with heparin (200 IU), followed by anesthesia with thiopental (40 mg/kg), pentobarbital (30 mg/kg), urethane (1.2 g/kg), either, or halothane and sacrificed by decapitation. The isolated heart (5 to 8 per group) was perfused with Locke solution by the Langendorff method and the left coronary artery was ligated for 10 min. The incidence of reperfusion arrhythmias (100%) was similar in hearts of control and previously anesthetized rats, but the duration of the arrhythmias was significantly increased by anesthesia (5-fold with thiopental, 15-fold with pentobarbital, ether and halothane, and 30-fold with urethane). In hearts taken from unanesthetized rats and perfused with Locke solution containing anesthetics (5-7 per group), the duration of reperfusion arrhythmias decreased with thiopental (0.23 +/- 0.15 min), did not change with pentobarbital (1.14 +/- 0.26 min) and increased with urethane (16.10 +/- 5.60 min). Our results show that anesthetics alter the duration of reperfusion arrhythmias in the isolated rat heart.

Effects of toxin Ts-gamma, purified from Tityus serrulatus scorpion venom, on the isolated rat atria

By using a pair of silver/silver-chloride electrodes it was possible to record, simultaneously, the atrial electrogram and the atrial contractile force of rat atria, in an organ bath, containing Krebs-Ringer solution (30 degrees C, pH 7.4, bubbled with 95% O2 and 5% CO2). Addition of toxin Ts-gamma, purified from Tityus serrulatus scorpion venom, into the bath (1 microgram/ml), evoked complex effects characterized by an initial reduction of both rate and contractile force, followed by increase of force and reduction of rate and finally by reduction of both rate and force. The increase of contractile force was prevented by metoprolol and is, therefore, adrenergic in nature. The reduction of rate was concomitant with changes in the atrial electrogram in which a positive P wave was replaced by a diphasic P wave, while the positive Ta wave was depressed. Experiments with tetrodotoxin, atropine and physostigmine indicate that these effects are due to the release of acetylcholine from vagal endings.

Effects of crotoxin on the isolated guinea pig heart

The effects of crotoxin, isolated from the venom of the South American rattlesnake, Crotalus durissus terrificus, were investigated on isolated guinea pig hearts, perfused with Locke solution, by the Langendorff method. The cardiac beats and the electrocardiogram were simultaneously registered and the creatine kinase (CK) activity of the perfusate measured. Crotoxin was infused (4.5 x 10(-8) M and 2.3 x 10(-7) M) into the heart during 90 min, and induced a remarkable decrease in the contractile force, without a significant reduction of heart rate, increased the P-R interval and displaced the S-T segment. The activity of CK only increased in the late phases of the experiments, when the force of contraction was below 25% of the control value. Arrhythmias were uncommon and no alterations of QRS duration or Q-Tc interval were observed. The reduction of the contractile force and the increase in CK activity were completely prevented by bovine serum albumin, whereas lanatoside C did not interfere with the toxin action. A bolus injection of crotoxin (11 +/- 2 nmoles) also induced a decrease of contractile force without reduction of heart rate. This decrease of force was partially prevented by indomethacin, but not by atropine. It is suggested that the reduction of contractile force evoked by crotoxin is due probably to release of free fatty acids and lysophospholipids (initial effect) and to a cellular lesion (late effect).

Superovulation in cattle: A combined treatment using syncromate B with either pregnant mare serum gonadotrophin or follicle stimulating hormone

A comparison between different superovulatory treatments in dairy cattle was carried out at a commercial embryo transfer unit in Israel. Both pregnant mare serum gonadotrophin (PMSG) and follicle stimulating hormone (FSH) were used, either alone or combined with Syncromate B (SMB). The use of PMSG + SMB significantly decreased the number of corpora lutea present at the time of embryo collection 7 d after insemination, as compared with other treatment regimens. Consequently, a significantly lower number of ova was found in those animals treated with PMSG + SMB. Better superovulatory responses were obtained when FSH, rather than PMSG, was used, regardless of whether they were administered alone or combined with SMB. It was clear that the use of SMB combined either with PMSG or FSH resulted in poorer responses than when either gonadotrophin was used alone.

Effect of indomethacin on generation of chemotactic activity in inflammatory exudates induced by carrageenan

Chemotactic activity of protein origin was demonstrated in carrageenan-induced pleural exudates by the chemotactic response of neutrophils in the modified Boyden chamber. The activity was partly neutralized by monospecific antisera to complement component 5 and was destroyed by trypsin and chymotrypsin treatment but it differed from that in rat serum or plasma in that it was stable for 30 min at 56 degrees C. Indomethacin (5 mg/kg i.v.) reduced equally protein content (56%) and total chemotactic activity (58%); i.e., chemotactic activity/mg of exudate protein was unchanged. Intrapleural injection of autologous or homologous serum also induced an infiltration of neutrophils; the protein content of the pleural fluid decreased by 60-70% in 4 h, whereas with carrageenan there was a progressive increase in exudate protein. When serum was injected in two doses to maintain protein levels comparable to those found following carrageenan injection, the number of neutrophils in the exudates was also comparable. In contrast to carrageenan, the response to serum was not inhibited by indomethacin. From these and other data we suggest that the exudate chemotactic activity is generated from plasma protein and that indomethacin acts primarily to reduce extravasation of plasma and consequently generation of chemotactic activity.

Dextran and carrageenan evoke different inflammatory responses in rat with respect to composition of infiltrates and effect of indomethacin

A study of the anti-inflammatory reaction after the injection of dextrans (60 mg) of various molecular weights (10,000-2,000,000) or carrageenan (0.5 mg) into the rat pleural cavity revealed two types of response. The dextrans induced within 30 min partial degranulation of mast cells and a rapid accumulation of fluid with little protein and a few neutrophils. This response was not suppressed by treatment with indomethacin. Carrageenan, in contrast, caused no mast cell degranulation, histamine release or early edema, but a progressive accumulation of a protein-rich exudate which contained large numbers of neutrophils. This response was inhibited by indomethacin. A commercial variety of dextran (mw 250,000) produced both types of response in which a rapid infiltration of protein-free fluid into the pleural cavity was followed by the appearance of protein and numerous neutrophils. The major plasma proteins were identified in exudates collected 4 hr after the injection of either carrageenan and the commercial dextran; in both cases, the numbers of neutrophils were related to the protein content of the exudate. The data suggest that inflammatory infiltrates may be formed through two distinct mechanisms: one associated with transudation of protein-free fluids, the other to exudation of plasma proteins and neutrophils. There are indications that these responses may involve different mediators.

Effects of a purified scorpion toxin (tityustoxin) on the isolated guinea pig heart

To study the cardiac effects induced by purified scorpion toxin (tityustoxin, TsTX), without circulatory and respiratory influences, isolated guinea pig hearts were used. Single injections of 10, 20 or 30 micrograms TsTX induced positive inotropic and chronotropic effects in the majority of the experiments. The inotropic effects were dose-dependent. Simultaneous recording of the electrical activity of the heart showed sinus tachycardia, T wave inversion and ST segment deviations. Sinus bradycardia and/or A-V block were recorded in some experiments, simultaneously with the positive inotropic effects. After these initial events, the larger dose of TsTX elicited periodic changes of heart rate (in 70% of the experiments) which were explained by wandering pacemakers. During these periodic changes in heart rate, the electrocardiogram showed sinus bradycardia, idioventricular rhythm, complete or partial A-V block, sinus tachycardia, sinus arrest and junctional rhythm. The coronary flow varied inversely with the inotropism and the cardiac rate, but the changes in flow were related mainly to the inotropism. The effects of TsTX on the electrocardiogram, inotropism and coronary flow spontaneously disappeared 15-20 min after toxin injection. The arrhythmias induced by TsTX were blocked either by propranolol or by atropine and are assumed to be due to the release of catecholamines and acetylcholine from postganglionic nerve fibers in the heart.

Inhibition of the expression of the "A" system of amino acid transport by anti-inflammatory drugs during cell culture growth and mitogenic stimulation of thymus lymphocytes

alpha-Methylaminoisobutyric acid uptake is mediated by two components in a variety of cell culture lines as well as in freshly isolated thymus lymphocytes. In all cell types, one component of uptake had characteristics similar to that of the "A" system and was selectively inhibited by the nonsteroidal anti-inflammatory drugs. Detailed studies with indomethacin showed that, in the presence of drug, a marked decrease in Vmax occurred with no impairment in the apparent affinity (Km) of the uptake system for either the amino acid or Na+ ion. Upon removal of drug, the capacity (Vmax) of the cell lines to take up amino acid recovered over the course of 6 hr. It is postulated that this time course may be related to a change in the number of functional carriers in the cell membrane. Marked increases in the rate of alpha-methylaminoisobutyric acid uptake by the Na+-dependent component were observed during exponential growth of cell cultures and in thymus lymphocytes stimulated by concanavalin A or amino acid deprivation. Irrespective of the cell type or mechanism of stimulation, indomethacin either blocked or partially suppressed this increase. Suppression of the Na+-dependent component of alpha-methylaminoisobutyric acid uptake was also evident in lymphocytes from indomethacin-treated rats. Selective inhibition of the A system before DNA synthesis may be one mechanism by which the anti-inflammatory drugs exert their in vitro cytostatic and in vivo immunosuppressive action

Phylogeny of histamine in vertebrate brain

Measurement of histamine and its metabolizing enzymes in a variety of chordate species indicated that histamine and histamine methyltransferase were present in brain of all vertebrate species with a recognizable brain structure. Diamine oxidase was absent in mammalian brain but was present in brain of lower vertebrates. Histamine levels were especially high in amphibia and fish brains, in which the phylogenetically newer parts of the brain were less well-developed. In the spiny dogfish (as in mammals), brain histamine levels were highest in the midbrain regions. In contrast to brain, histamine levels were low in muscle, skin and intestine of all aquatic species.

Influence of indomethacin and other anti-inflammatory drugs on mobilization and production of neutrophils: studies with carrageenan-induced inflammation in rats

The intrapleural injection of carrageenan in the rat, after a delay of 90 min, resulted in the accumulation of 100 to 300 million neutrophils in the pleural cavity, a 6-fold increase in the numbers of circulating neutrophils and the mobilization of large numbers of neutrophils from bone marrow. Thymidine labeling of bone marrow cells showed that neutrophils underwent a period of maturation (2--3 days) before release into the circulation and accumulation in the pleural cavity. Nonsteroidal anti-inflammatory drugs reduced, in a dose-dependent manner, the accumulation of white cells and fluid. Indomethacin, the most potent of the drugs tested, was equally effective whether given 30 min before or 90 min after carrageenan. This drug had no significant effect on the production or number of white cells in bone marrow, spleen or thymus. In contrast, methotrexate suppressed the inflammatory reaction only after prolonged treatment had produced almost complete depletion of cells in bone marrow and dexamethasone could be given in doses that largely depleted thymus and spleen of their white cells but which had little effect on neutrophil accumulation. It is concluded that neutrophils were mobilized from stores of mature cells in bone marrow and that indomethacin suppressed mobilization of these cells without impairing normal white cell homeostasis.

Evidence that histamine does not participate in carrageenan-induced pleurisy in rat

The injection of carrageenan into the rat pleural cavity provoked an intense inflammatory reaction with the formation of an exudate which contained mainly neutrophils but which was also rich in mast cells and histamine. There was, however, no evidence that histamine participated in the reaction. The mast cells remained intact, and no increase in extracellular histamine levels was observed. Prior treatment with bot H1 and H2 histimine receptor antagonists or depletion of the histamine stores by pretreatment with compound 48/80 did not alter the reaction. In contrast, the exudate formed in response to the intrapleural injection of small doses (0.05 mg/kg) of compound 48/80 was reduced by pretreatment with the antihistamine compounds and, unlike the exudate formed after carrageenan injection, was devoid of neutrophils. Since saline washes of the pleural cavity of untreated rats had histamine and mast cell contents similar to those of the exudates of the carrageenan-treated rats, the source of histamine appeared to be mast cells from the pleural cavity.

Supersensitivity induced by the toxin of Brazilian scorpion venom (Tityus serrulatus Lutz e Mello)

The purified toxin of the Brazilian scorpion venom (TsTX) enhances the pharmacological actions of directly and indirectly acting substances on several preparations. The enhancing action of TsTX is more pronounced for the indirectly acting drugs, which is highly suggestive of a prejunctional site of action. Secondarily, TsTX does also produce an unspecific increase of sensitivity at the level of the pharmacological receptor itself. The mechanism by which these changes are brought about remains to be determined.

Prejunctional effects of a purified toxin from the scorpion Tityus serrulatus: release of 3H-noradrenaline and enhancement of transmitter overflow elicited by nerve stimulation

The effects of a purified fraction of the venom of the Brazilian scorpion, Tityus serrulatus, were studied in isolated guinea-pig atria previously labelled with 3H-noradrenaline. Exposure to 0.3 and 1.0 mug/ml of the scorpion toxin resulted in a long lasting positive chronotropic effect which was concentration-dependent. The increase in atrial rate coincided with an enhancement in spontaneous outflow of radioactivity. The increase in outflow of radioactive products elicited by exposure to 1.0 mug/ml of the scorpion toxin was approximately 3-fold. 3H-noradrenaline accounted for 60% of the total increase in outflow of radioactivity elicited by the scorpion toxin and the 3H-deaminated glycol (3,4-dihydroxyphenyl-glycol) represented the main metabolite formed, accounting for approximately 35% of the total release. 20 min after exposure to 1.0 mug/ml of the scorpion toxin the overflow of the labelled transmitter elicited by accelerans nerve stimulation (4 Hz, during 60 sec. supramaximal voltage) was increased 8-fold. This effect of the scorpion toxin appears to be unrelated to inhibition of neuronal uptake, block of alpha-adrenoceptors or stimulation of beta-adrenoceptors. Consequently, in addition to releasing noradrenaline, the scorpion toxin enhances transmitter overflow elicited by nerve stimulation through a prejunctional effect which appears to reflect a nove mechanism of action.