Hysterosalpingography: a step up for dose reduction.

AIM: To evaluate the efficiency of last image capture in interpreting a hysterosalpingogram (HSG) when compared to conventional spot views; to confirm its validity in showing pathology; to establish its use as the preferred method; and to decrease the radiation dose to the patient. MATERIALS AND METHODS: The study population consisted of women aged ≥18 years. A standard technique was performed including additional five last image capture after each spot view. Every patient had two stacks of images, one with the exposure film and one with the last image capture. The images were interpreted separately (high-dose versus low-dose) and blindly by two radiologists with different levels of training assessing for uterine abnormalities, fallopian tube abnormalities, peritoneal spillage, and incidental findings. Inter-reading variability was calculated using Kohen's kappa. RESULTS: Discrepancies between exposure film and last image capture were detected in only a minority of cases for all variables. Except for the presence of strictures, there was at least substantial agreement between the readers and almost perfect agreement regarding peritoneal spillage and fallopian tube patency, both on exposure film and last image capture. CONCLUSION: Reduction in radiation dose without compromising the diagnostic efficacy of HSG is mandatory. If the study is of sufficient quality and deemed negative on last image capture, conventional spot view can be avoided. If further detail is required, standard spot views can still be obtained. Using last image capture instead of spot films has the potential to reduce the overall radiation dose by up to 78%.

Impact of human coronavirus infections on paediatric patients at a tertiary paediatric hospital: a retrospective study of the prepandemic era.

BACKGROUND: Human coronaviruses (HCoVs) are important respiratory pathogens in humans and animals. Most HCoVs are emerging pathogens, with five known human pathogens identified in the last two decades. AIM: To examine the clinical course of HCoV infection in children to improve understanding of severity and outcomes. METHODS: A retrospective review was undertaken of all encounters of children with known HCoV infection at a tertiary paediatric hospital from January 2015 to January 2018. Electronic medical records were reviewed for demographic data, HCoV type, viral co-pathogens, time to testing, need for hospitalization, requirement for higher-level care (HLC) including intensive care unit management and requirement for oxygen support, radiographic findings suggestive of lower respiratory tract (LRT) disease, and length of stay (LOS). FINDINGS: In total, 450 encounters for 430 different patients were identified, with the majority (85%) being inpatient. OC43 was the most common HCoV. Younger patients (age <5 years) had higher probability of hospitalization [adjusted odds ratio (aOR) 2.2, 95% confidence interval (CI) 1.2-4.1], requirement for HLC (aOR 1.8, 95% CI 1.0-3.1) and presence of LRT findings on chest radiographs (aOR 1.7, 95% CI 1.01-2.9). Clinical outcomes did not differ between HCoV types, except LOS which was longer for 229E. Fifty-two (11%) encounters were detected after 3 days of hospitalization (median 25.5 days), suggesting possible nosocomial infection. CONCLUSION: HCoVs are important respiratory pathogens in the paediatric population, especially among patients aged <5 years who are at increased risk for severe disease. The role of HCoVs as hospital-acquired pathogens may be underappreciated.

Reliability, factor analysis and internal consistency calculation of the Insomnia Severity Index (ISI) in French and in English among Lebanese adolescents.

OBJECTIVES: Our goal is to validate and to verify the reliability of the French and English versions of the Insomnia Severity Index (ISI) in Lebanese adolescents. STUDY DESIGN: A cross-sectional study was implemented. METHODS: 104 Lebanese students aged between 14 and 19 years participated in the study. The English version of the questionnaire was distributed to English-speaking students and the French version was administered to French-speaking students. A scale (1 to 7 with 1 = very well understood and 7 = not at all) was used to identify the level of the students' understanding of each instruction, question and answer of the ISI. The scale's structural validity was assessed. The factor structure of ISI was evaluated by principal component analysis. The internal consistency of this scale was evaluated by Cronbach's alpha. To assess test-retest reliability the intraclass correlation coefficient (ICC) was used. RESULTS: The principal component analysis confirmed the presence of a two-component factor structure in the English version and a three-component factor structure in the French version with eigenvalues > 1. The English version of the ISI had an excellent internal consistency (α = 0.90), while the French version had a good internal consistency (α = 0.70). The ICC presented an excellent agreement in the French version (ICC = 0.914, CI = 0.856-0.949) and a good agreement in the English one (ICC = 0.762, CI = 0.481-890). The Bland-Altman plots of the two versions of the ISI showed that the responses over two weeks' were comparable and very few outliers were detected. CONCLUSION: The results of our analyses reveal that both English and French versions of the ISI scale have good internal consistency and are reproducible and reliable. Therefore, it can be used to assess the prevalence of insomnia in Lebanese adolescents.

Quality of amoxicillin formulations in some Arab countries.

BACKGROUND AND OBJECTIVE: The problem of counterfeit and substandard drugs is recurrent in developing countries where antibiotics account for the majority of such products. The aim of this study was to investigate the quality of locally produced and imported amoxicillin products on the Lebanese, Jordanian, Egyptian and Saudi markets. METHODS: One hundred and eleven samples of amoxicillin capsules and suspensions purchased from retail pharmacies were analysed for their drug content by a validated chromatographic method in order to verify if they complied with pharmacopeial requirements. Suspensions were analysed for their drug content immediately after reconstitution as well as 7 or 14 days later according to the expiry date. RESULTS AND DISCUSSIONS: Fifty-six per cent of amoxicillin capsules did not meet the United State Pharmacopeia (USP) requirements and most had amounts bordering the lower limit. Individual average values as low as 59% of the label claim were detected. Eight per cent of the samples of suspensions gave measurements outside pharmacopeial limits. Furthermore, after 7 or 14 days, 38% of the samples were outside the pharmacopeial limits. All the European brands met the pharmacopeial limits except for one. CONCLUSION: Our results reveal the high incidence of substandard drugs on some Arab market where several factors might jeopardize the quality status of medicines: lack of effective quality assurance system during manufacture in both Arab and export countries, and uncontrolled storage conditions, especially unsuitable pharmacy premises. Use of substandard antibiotic preparations increases the risk of therapeutic failure and the emergence of drug-resistant microorganisms.

Environmental noise in Beirut, smoking and age are combined risk factors for hearing impairment.

Effect of smoking and environmental noise on hearing impairment was investigated in 440 people aged 21-50 years living in Beirut. Participants were divided into 4 groups: nonsmokers and smokers living in noisy areas (70-90 dBA) and non-smokers and smokers living in quiet areas (45-55 dBA). Smoking was associated with hearing loss at 8000 Hz, in both bivariate and multivariate analysis. An additive interaction at high frequencies (mostly at 8000 Hz) between smoking and noise appeared after age 40 years. At age 21-39 years, neither smoking nor environmental noise had a significant adverse effect on hearing capacity at low frequencies.

Effect of cucurbitacins on bilirubin-albumin binding in human plasma.

The aim of this study is to investigate the effect of three cucurbitacins (Cuc) E, D and I on the bilirubin-albumin binding, both in human serum albumin (HSA) and in plasma. Bilirubin-HSA solution and plasma free of cucurbitacins were prepared as well as others containing serial concentrations of cucurbitacins. The concentration of unbound bilirubin was determined in bilirubin-HSA solution and the direct and total bilirubin concentrations were measured in plasma (with normal or elevated bilirubinemia) by Jendrassik and Grof method. In the conditions we adopted Cuc E and D (to a lesser extent), decreased the levels of unbound bilirubin in bilirubin-HSA solution and decreased direct bilirubin concentration and total bilirubin concentration in plasma in a dose-dependent manner while Cuc I had no effect. The effect of Cuc is related to the presence of native HSA. Thus, when albumin was absent or has been denatured by heating or by urea, Cuc E did not modify bilirubin levels, suggesting that the native structure of albumin is essential for such activity. The interaction of HSA with Cuc E was investigated by fluorescence spectroscopy. Cuc E increased the intrinsic fluorescence of the protein and the magnitude of fluorescence intensity of bilirubin-albumin complex. We concluded that Cuc E and D produced a rearrangement in the structure of albumin, particularly in the domain-II, resulting in an increase in the binding of bilirubin to albumin regardless to whether it's conjugated to glucuronic acid or unconjugated.

Hydrogen adsorption measurements and modeling on metal-organic frameworks and single-walled carbon nanotubes.

Hydrogen adsorption measurements on Al-, Cr-, and Zn-based metal-organic frameworks (MOFs) and single-walled carbon nanotubes (SWNTs) are presented. The measurements were performed at temperatures ranging from 77 to 300 K and pressures up to 50 atm using a volumetric approach. The maximum excess adsorption at 77 K ranges from 2.3 to 3.9 wt % for the MOFs and from 1.5 to 2.5 wt % for the SWNTs. These values are reached at pressures below 40 atm. At room temperature and 40 atm, modest amounts of hydrogen are adsorbed (<0.4 wt %). A Dubinin-Astakhov (DA) approach is used to investigate the measured adsorption isotherms and to retrieve energetic and structural parameters. The adsorption enthalpy averaged over filling is about 2.9 kJ/mol for the MOF-5 and about 3.6-4.2 kJ/mol for SWNTs.

Protective effect of taurine against free radicals damage in the rat myocardium.

Free radicals are highly cytotoxic to the heart and are involved in ischemia/reperfusion injury. In this study, we tested the ability of taurine to neutralize the deleterious effects of free radicals generated ex vivo and in vitro. Taurine was added at a concentration of 0.1 mM to the drinking water of experimental rats during 6 months. The animal hearts were then isolated and submitted to regional ischemia and reperfusion; ventricular fibrillation was significantly reduced as compared to a control group of non-treated animals. Moreover, at a concentration of 1 mM, taurine provided significant cardio-protection against the deleterious effect of free radicals generated by the electrolysis of Krebs-Henseleit buffer. When isolated hearts were perfused with electrolysed buffer, extensive fiber necrosis occurred, as observed by staining with nitro blue tertrazolium, a soluble dye which yields a dark blue formazan stain in the presence of reducing agents This stain was barely detectable when taurine was added to the perfusing electrolysed buffer. To further understand the protecting mechanism of taurine, we used xanthine-xanthine-oxidase as a superoxide (O2-) generating system and monitored the O2- through yield O2--dependent cytochrome c reduction. We demonstrated that taurine did not affect this system, which indicated that it did not scavenge O2- directly. On the other hand, taurine inhibited the auto-oxidation of adrenaline to adrenochrome at pH 7.8 where this auto-oxidation is O2--independent and superoxide dismutase insensitive. We thus conclude that taurine acts as a potent, but non-specific, scavenger of free radicals that cause heart damage and protects against reperfusion-induced ventricular

Effects of nicotine on thromboxane/prostacyclin balance in myocardial ischemia.

It has been proven that nicotine contributes to cardiovascular diseases, although its precise mechanism of action is still unclear. The purpose of this study is to find how nicotine may complicate myocardial ischemia by affecting the thromboxane/prostacyclin (TXA(2)/PGI(2)) balance. We used four groups (n=7 each) of isolated and perfused rabbit hearts according to Langendorff method: (i) control group; (ii) group submitted to 1 microM nicotine perfusion during 60 min; (iii) group submitted to a regional ischemia by ligation of the left descending coronary artery during 60 min and (iv) group submitted to nicotine perfusion during ischemia. Levels of TXB(2) and 6-keto PGF(1alpha), the stable metabolites of TXA(2) and PGI(2) were then determined in the microsomes of the hearts by radioimmunoassay. The results showed that (1) a TXA(2) synthetase activity is present in the myocardium, and this activity, as well as that of PGI(2) synthetase, is decreased by a 60min ischemia; (2) TXA(2) and PGI(2) activities are not affected by nicotine in the normal myocardium and (3) nicotine infusion during ischemia contributes to the increase of TXA(2)/PGI(2) ratio further by decreasing PGI(2). Therefore, these results provide one explanation on how nicotine might worsen myocardial ischemia.

HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome versus severe preeclampsia: onset at < or =28.0 weeks' gestation.

OBJECTIVE: Our purpose was to determine whether the onset of the HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome in women at < or =28.0 weeks' gestation is associated with an increased risk of adverse maternal and perinatal outcomes in comparison with the risk for women with severe preeclampsia but without the HELLP syndrome at a similar gestational age. STUDY DESIGN: Sixty-four patients with either the HELLP syndrome (n = 32) or severe preeclampsia but absent HELLP syndrome laboratory test results (n = 32), admitted at < or =28.0 weeks' gestation between July 1, 1992, and April 30, 1999, were studied. Maternal and perinatal outcomes were compared between the 2 groups. Statistical analysis was performed by the Student t test and the Fisher exact test. RESULTS: There were no significant differences between the 2 groups regarding African-American race (59% vs 75%), nulliparity (50% vs 56%), or the use of corticosteroids (59% vs 78%). There were no maternal deaths. One woman with the HELLP syndrome had a liver hematoma. The rate at which transfusion of blood products was required was significantly greater in women with the HELLP syndrome than in those with severe preeclampsia only (25% vs 3%; P <.05). There were no significant differences between the 2 groups with respect to eclampsia (16% vs 13%), abruptio placentae (6% vs 9%), disseminated intravascular coagulopathy (13% vs 0%), pulmonary edema (13% vs 6%), acute renal failure (3% vs 0%), pleural effusion (3% vs 3%), or ascites (6% vs 16%). No significant differences were found between the 2 groups with respect to neonatal death (11% vs 17%), respiratory distress syndrome (78% vs 86%), or composite neonatal morbidity. CONCLUSIONS: Except for the need for transfusion of blood products in women with the HELLP syndrome, onset at < or =28.0 weeks' gestation is not associated with an increased risk of adverse maternal or neonatal outcomes in comparison with the risk for women with severe preeclampsia but without the HELLP syndrome at a similar gestational age.

Risk factors for adverse maternal outcomes among women with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.

OBJECTIVE: This study was undertake to determine risk factors for adverse maternal outcomes among women with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome. STUDY DESIGN: Maternal medical records of pregnancies complicated by HELLP syndrome managed between July 1, 1992, and April 30, 1999, were reviewed. Risk factors evaluated included maternal age, parity, race, previous preeclampsia, chronic hypertension, gestational age at diagnosis, mean arterial blood pressure, nadir blood platelet count (<50,000 cells/microL vs > or =50,000 cells/microL), and peak serum levels of aspartate aminotransferase and lactate dehydrogenase. Maternal outcome variables analyzed included eclampsia, abruptio placentae, disseminated intravascular coagulopathy, pulmonary edema, pleural effusion, ascites, acute renal failure, liver hematoma, need for transfusion of blood products, cesarean delivery, and death. Statistical analysis was performed with the Student t test, the chi(2) test, and logistic regression analysis. RESULTS: A total of 183 women with HELLP syndrome were studied. Eclampsia was present in 6%, abruptio placentae was present in 10%, and disseminated intravascular coagulopathy was present in 8%. Forty-one women (22%) required transfusion of blood products. Incidence of eclampsia significantly decreased with increasing gestational age, from 16% at < or =28 weeks' gestation to 3% at >32 weeks' gestation (P <.05) and was higher among African American patients than among white patients (12% vs 3%; P <.05). Logistic regression analysis showed an independent relationship between eclampsia and race (P <.05). Incidence of abruptio placentae was higher among women with previous preeclampsia than among women without this clinical history (26% vs 5%; P <.05). Disseminated intravascular coagulopathy was significantly associated with abruptio placentae (P <.0001) and acute renal failure (P <.0001). A nadir platelet count of <50, 000/microL, a peak serum aspartate aminotransferase level of >150 U/L, and a peak serum lactate dehydrogenase level of >1400 U/L were not independent risk factors for adverse outcome. CONCLUSIONS: Among women with HELLP syndrome, African American race is a risk factor for eclampsia. Both acute renal failure and abruptio placentae are associated with disseminated intravascular coagulopathy. Laboratory parameters of HELLP syndrome are not independent risk factors for adverse maternal outcome.

Influence of extracellular potassium on the antiarrhythmic effect of global preconditioning in isolated perfused rat hearts.

The objective of this study was to investigate if a variation in extracellular-K+ concentrations alters the effects of global pre-conditioning on ischemia-induced arrhythmias. Rat hearts were Langendorff-perfused with Krebs-Henseleit solution and randomised in 8 groups (n = 12/group): four control groups (K+: 2, 4, 6, or 8 mmol/L) which underwent 30-min coronary artery occlusion and four preconditioned groups (K+: 2, 4, 6, or 8 mmol/L) in which the 30-min regional ischemia was preceded by 2 cycles of 3 min global ischemia. In the presence of low K+ (2 mmol/L), there were no differences between control and preconditioning groups in the number of ventricular premature beats (VPBs): 194 +/- 64 vs. 217 +/- 81, the incidence of ventricular tachycardia (VT): 100% vs. 100% and of ventricular fibrillation (VF): 100% vs. 100%. In the presence of normal K+ concentration (4 mmol/L), ischemic preconditioning reduced the number of VPBs from 88 +/- 26 to 25 +/- 10, (p < 0.05), the incidence of VT from 100 to 50% (p < 0.05), and of VF from 67 to 16% (p < 0.05). In the condition of higher K+ concentration (6 mmol/ L), VPBs (34 +/- 8 vs. 11 +/- 4), the incidence of VT (100% vs. 25%; p < 0.05 ) and VF (25% vs. 8%) were further reduced in preconditioned hearts. In the condition of K+ concentration (8 mmol/L), there were no differences in VPBs (11 +/- 3 vs. 7 +/- 2), the incidence of VT (8% vs. 0%) and VF (8% vs. 0%) between control and preconditioned hearts. Our data show that ischemic preconditioning affords protection against arrhythmias during coronary artery occlusion in the isolated rat heart and that hypokalemia abolishes the antiarrhythmic effects of global preconditioning.

The anti-thromboxane A2 synthetase activity of myocardial tissue and its variation during ischemia and reperfusion in isolated rabbit heart.

In this investigation, an anti-thromboxane A2 (TXA2) synthetase activity in the myocardial tissue, which can be modulated by ischemia and reperfusion, was observed. Regional ischemia was induced by 60 min occlusion of the left anterior descending coronary artery in isolated Langendorff rabbit hearts. Biosynthesis of TXA2 was carried out by using arachidonic acid (AA) as substrate, horse platelet microsomes (HPM) as the source of TXA2 synthetase and left ventricle microsomes (LVM) from ischemic and non-ischemic areas as effectors TXB2, the stable metabolite of TXA2, was determined by radioimmunoassay. Experiments carried out under the adopted conditions showed that LVM from control hearts were able to inhibit by up to 50% the biosynthesis of TXA2 from HPM. This anti-TXA2 synthetase activity was more pronounced when LVM from the non-ischemic area were used, rather then LVM from the ischemic one. A 60 min reperfusion decreased the anti-TXA2 activity. A superfused rabbit aorta strip was also used as a cascade bioassay to study the effect of LVM on the TX2-synthetase activity of HPM, and this confirmed our findings. These results suggest that the left ventricle possesses a self-defense mechanism against acute myocardial ischemia, independently from the circulation. The postulated mechanism may be initiated in the non-ischemic area.

Successful pregnancy outcome following Tompkins metroplasty done early in pregnancy.

A hysterosalpingogram revealed a septate uterus in a 29 year old nulliparous woman with a history of recurrent pregnancy loss. The patient underwent Tompkins metroplasty in the proliferative phase of the menstrual cycle. One month after the operation she presented with a delay in her menses and a positive pregnancy test. Ultrasound revealed a viable fetus commensurate with 10 weeks gestation, making the gestation period 5 weeks at the time of surgery. After reviewing the patient's menstrual history it was found that the period the patient had before surgery was on time but with unusually minimal bleeding. A repeat ultrasound scan for anomaly done 7 weeks later was commensurate with 17 weeks gestation. The patient carried her pregnancy for the first time until approximately 37 weeks when she delivered by Caesarean section a healthy female baby weighing 3700 g.

Protective effects of taurine against reperfusion-induced arrhythmias in isolated ischemic rat heart.

The protective effect of taurine (CAS 107-35-7) against reperfusion-induced arrhythmias has been investigated in isolated perfused rat heart (Langendorff method). Partial ischemia was induced by occlusion of left descending artery for 15 min, followed by 10 min reperfusion. Left ventricular pressure and epicardial ECG were continuously monitored before and during ischemia and reperfusion. A control group was submitted to partial ischemia without taurine treatment. Three groups were submitted to partial ischemia, under taurine (10 mmol/l) treatment in the Krebs-Henseleit perfusing buffer during ischemia only (group 1), at reperfusion (group 2) and throughout the experimental period (group 3). Malondialdehyde levels were measured as an index of lipid peroxidation and heart muscle damage. The incidence of irreversible ventricular fibrillation was significantly diminished from 83% (control group) to 36% in group 1, 42% in group 2 and 16% in group 3. The incidence of premature ventricular beats and ventricular tachycardia at reperfusion as well as malondialdehyde levels were significantly decreased under taurine treatment. The results indicate that taurine protects ischemic heart against reperfusion-induced arrhythmias, via both its properties as membrane stabilizer and oxygen free radical scavenger.

[Cardiovascular risk factors: smoking in the context of recent events in Lebanon]. / Facteurs de risque cardio-vasculaire: le tabagisme dans le contexte des derniers événements du Liban.

Epidemiological studies have demonstrated that cigarette smoking increases the incidence of myocardial infarction and sudden death. Psychological and physical stress, like smoking, activates the sympathetic adrenal medullary and pituitary-adrenal cortical systems. We therefore thought that the effects of stress and smoking together might increase the risk of cardiovascular disease. The seventeen-year Lebanese war was a source of real psychological stress. It was a very traumatic time for many citizens, forced to cope with the situation and its tragic consequences. We evaluated the effects of smoking and traumatic experiences during war using a study population of 46 Lebanese men aged between 28 and 45. We determined hemodynamic characteristics, such as heart rate and arterial blood pressure, and plasma indicators (cortisol and thromboxane concentrations). We found that smoking itself significantly increased all of these variables. The increase was larger, but not significantly so, in smokers who had experienced traumatic events during the war. This study suggests that preventive efforts should be directed at those groups with combinations of risk factors (e.g. smoking and stress) rather than at groups with one risk factor only. Accurate assessment of risk factors, their predictive value and their interactions are vital for any program of preventive measures.

Demonstration of the production of oxygen-centered free radicals during electrolysis using E.S.R. spin-trapping techniques: effects on cardiac function in the isolated rat heart.

The present study was designed to identify the free radicals generated during the electrolysis of the solution used to perfuse isolated rat heart Langendorff preparations. The high reactivity and very short half-life of oxygen free radicals make their detection and identification difficult. A diamagnetic organic molecule (spin trap) can be used to react with a specific radical to produce a more stable secondary radical or "spin adduct" detected by electron spin resonance (ESR). Isovolumic left ventricular systolic pressure (LVSP) and left ventricular end diastolic pressure (LVEDP) were measured by a fluid-filled latex balloon inserted into the left ventricle. The coronary flow was measured by effluent collection. Electrolysis was performed with constant currents of 0.5, 1, 1.5, 3, 5, 7.5, and 10 mA generated by a Grass stimulator and applied to the perfusion solution for 1 min. A group of experiments was done using a 1.5 mA current and a Krebs-Henseleit (K-H) solution containing free radical scavengers (superoxide dismutase (SOD): 100 IU/ml or mannitol: 50 mM). Heart function rapidly declined in hearts perfused with K-H buffer that had been electrolyzed for 1 min. The addition of mannitol (50 mM) to the perfusion solution had no effect on baseline cardiac function before electrolysis while SOD (100 IU/ml) increased the coronary flow. However, SOD was more effective than the mannitol in protecting the heart against decreased of cardiac function, 5 min after the end of electrolysis. Samples of the K-H medium subjected to electrolysis were collected in cuvettes containing a final concentration of 125 mM 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and analyzed by spectroscopy. The ESR spectrum consisted of a quartet signal (hyperfine couplings aN = aH = 14.9 G) originating from the hydroxyl adduct signal, DMPO-OH. The intensity of the DMPO-OH signal remained stable during the 60 s of electrolysis and the quantity of free radicals induced by electrolysis was directly proportional to the intensity of the current. The addition of mannitol and SOD to the perfusate scavenged the hydroxyl radicals present in the solution, suggesting that both hydroxyl and superoxide radicals were formed during electrolysis.

Transient ischemia inhibits nonexocytotic release of norepinephrine following sustained ischemia in rat heart: is bradykinin involved?

Previous studies have demonstrated that transient ischemia inhibits the release of norepinephrine (NE) following a sustained ischemia. However, the mechanism underlying this inhibition is unknown. Therefore, this study was designed to investigate whether bradykinin (BK) may be involved in the inhibition of NE release following ischemic preconditioning. The effects of transient ischemia, exogenous BK, and kinin receptor blockers on NE release after a prolonged ischemia were tested in the isolated rat heart preparation. Three cycles of 5-min ischemia and reperfusion resulted in the reduction of NE release from 115.3 +/- 14.5 to 51.6 +/- 9.3 pmol.g-1 (p < 0.05) after 30 min of subtotal global ischemia. This effect was not prevented by the administration of either Lys-[Leu8]-des-Arg9-BK (1 mumol.L-1), a B1 antagonist, or HOE-140 (1 mumol.L-1), a B2 antagonist. Three cycles of 5-min BK or des-Arg9-BK infusion also resulted in a dose-dependent inhibition of NE release after 30 min of ischemia. The inhibitory effects of BK (1 mumol.L-1) or des-Arg9-BK (0.5 mumol.L-1) were blocked by Lys-[Leu8]-des-Arg9-BK (1 mumol.L-1), but not by HOE-140 (1 mumol.L-1). The results show that transient ischemia and BK protect sympathetic nerve endings in the isolated rat heart. The inhibition of NE release by pretreatment with BK is mediated by the activation of B1 receptors, whereas preconditioning provided by transient ischemia may be mediated by a different, yet unknown, mechanism in the rat heart.

Free radicals generated by electrolysis reduces nitro blue tetrazolium in isolated rat heart.

Oxygen free radicals (OFR) are highly cytotoxic when produced in the myocardium under certain pathological conditions. In isolated rat hearts perfused retrogradely, OFR were generated by electrolysis of the Krebs-Henseleit buffer (two platinum electrodes, DC current, 10 mA, 1 min). In order to find evidence that OFR are produced, we used nitro blue tetrazolium (NBT) a soluble compound which yields a dark blue formazan pigment in the presence of reducing agents. Hearts were subdivided into: control, electrolysed, NBT (3.3 mg/ml) perfusion during electrolysis in the presence or absence of scavengers. The xanthine-xanthine oxidase (XXO) system known to produce superoxide radical was used as a reference. Specimens were fixed with formaldehyde and stained with eosine or Kernechtrot in preparation for light microscopical examination. Several areas of acute necrosis expressed by hyalinisation and loss of striation were observed in electrolysed hearts which present a pattern of wavy disrupted myofibers and an increase in interstitial spaces. A very faint deposition of formazan was observed in some rare areas of NBT perfused heart. Only the electrolysed group perfused with NBT and the one perfused with XXO plus NBT presented an extensive formazan deposition, mostly in the areas of fibre necrosis. Formazan was barely detectable when superoxide dismutase plus catalase were perfused in the XXO system, while it was still apparent when perfused in electrolysed hearts. These results support the hypothesis that electrolysis can be used to generate different species of OFR and to evaluate the protective action of scavenger and antioxidants against OFR-induced myocardial damage.