Short- and long-term effects of proallatotoxin (ethoxyprecocene II) on Rhodnius prolixus females

Oogenesis and oviposition can be inhibited in female of Rhodnius prolixus by means of short-term experiment (first reproductive cycle) of a single dose of ethoxyprecocene II given by ingestion. The inhibition is dose-dependent as measured by oocyte growth, egg maturation and egg deposition. In a long-term experiment (second and third reproductive cycles) egg production and oogenesis can be partially or totally re-established by subsequent blood meals without ethoxyprecocene II. These findings suggest that in female R. prolixus, damage caused to corpus allatum by ethoxyprecocene II, in certain cases, is not irreversible.     

Short- and long-term effects of irradiation on bone regeneration

The aim of the present study is to quantify bone-regenerative capacity directly and 1 year after administration of 15 Gy 60Co irradiation. A titanium implant, the bone growth chamber, which in nonirradiated cases becomes filled with newly formed bone over a 4-week period, was inserted into each tibial metaphysis of 20 rabbits. In 10 animals the chambers were installed directly after irradiation, while in 10 other rabbits the implants were installed 1 year after the 60Co trauma. In both groups the bone-forming capacity on the irradiated side was compared to that of the contralateral, nonirradiated, control tibia. The amount of bone formed was determined by microradiography and microdensitometry. It was found that bone regeneration was depressed by 70.9 percent within a 4-week period after irradiation. At a follow-up of 1 year, the average depression of bone-forming capacity was only 28.9 percent. This means a recovery by a factor of almost 2.5. The clinical implications of these findings are discussed.     

Protective effects of N-n-butyl haloperidol iodide on myocardial ischemia-reperfusion injury in rabbits

N-n-butyl haloperidol iodide (F2), a novel compound derived from haloperidol, was synthesized by our drugs research lab. The present study aims to evaluate the protective effects of F2 on myocardial ischemia-reperfusion injury in vivo, and to try to find the protective mechanism of F2. The animal model of myocardial ischemia-reperfusion injury was established by ligaturing rabbit's left ventricular branch of coronary artery for 40 min and removing the ligation later to reperfuse for 40 min. Different doses of F2 were intravenously injected before the onset of ischemia. The changes of hemodynamics were recorded during the experiment, and the activities of superoxide dismutase (SOD), creatine kinase (CK), Ca2+-ATPase, Na+,K+-ATPase and the level of malondialdehyde (MDA) of myocardial tissue were detected after reperfusion. Administration of F2 could dose-dependently ameliorate the hemodynamics of ischemia-reperfusion injured myocardium. During the course of reperfusion, MAP, LVSP, +/-dP/dt(max) in all F2 groups were obviously higher than those in the ischemia-reperfusion control group, and LVEDP were lower. F2 could also reduce the production of MDA, and maintain the activities of SOD, Ca2+-ATPase, Na+,K+-ATPase, and minimize the leakage of CK out of myocardial cells in a dose-dependent manner. These results suggested that F2 had apparent protective effects against myocardial ischemia-reperfusion injury.     

Structures of (-)-epicatechin glucuronide identified from plasma and urine after oral ingestion of (-)-epicatechin: differences between human and rat

(-)-epicatechin is one of the most potent antioxidants present in the human diet. Particularly high levels are found in black tea, apples, and chocolate. High intake of catechins has been associated with reduced risk of cardiovascular diseases. There have been several reports concerning the bioavailability of catechins, however, the chemical structure of (-)-epicatechin metabolites in blood, tissues, and urine remains unclear. In the present study, we purified and elucidated the chemical structure of (-)-epicatechin metabolites in human and rat urine after oral administration. Three metabolites were purified from human urine including (-)-epicatechin-3'-O-glucuronide, 4'-O-methyl-(-)-epicatechin-3'-O-glucuronide, and 4'-O-methyl-(-)-epicatechin-5 or 7-O-glucuronide, according to 1H- and 13C-NMR, HMBC, and LC-MS analyses. The metabolites purified from rat urine were 3'-O-methyl-(-)-epicatechin, (-)-epicatechin-7-O-glucuronide, and 3'-O-methyl-(-)-epicatechin-7-O-glucuronide. These compounds were also detected in the blood of humans and rats by LC-MS. The presence of these metabolites in blood and urine suggests that catechins are metabolized and circulated in the body after administration of catechin-containing foods.     

Exercise-induced cardioprotection against myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion (IR) injury is a major contributor to the morbidity and mortality associated with coronary artery disease. Muscular exercise is a countermeasure to protect against IR-induced cardiac injury in both young and old animals. Specifically, regular bouts of endurance exercise protect the heart against all levels of IR-induced injury. Proposed mechanisms to explain the cardioprotective effects of exercise include alterations in coronary circulation, expression of endoplasmic reticulum stress proteins, increased cyclooxygenase-2 activity, induction of myocardial heat shock proteins, improved cardiac antioxidant capacity, and/or elevation of ATP-sensitive potassium channels on both the sarcolemmal and the mitochondrial inner membranes. Moreover, it seems possible that other, yet to be defined, mechanisms of exercise-induced cardioprotection may also exist. Of the known putative cardioprotective mechanisms, current evidence suggests that elevated myocardial levels of antioxidants and increased expression of sarcolemmal ATP-sensitive potassium channels are both contributors to exercise-induced cardioprotection against IR injury. At present, it is unclear if these two protective mediators act independently or interact to contribute to exercise-induced cardioprotection. Understanding the molecular basis for exercise-induced cardioprotection will provide the required knowledge base to develop therapeutic approaches to protect the heart during an IR insult.     

Short- and long-term effects of environmental urea on fecundity inDrosophila melanogaster

Previous studies have shown that exposure to urea-supplemented food inhibited fecundity inDrosophila females, and that this inhibition was not expressed when females were given a choice between regular and urea-supplemented food as an oviposition substrate. We assayed fecundity, on both regular food and urea-supplemented food, at 5, 15 and 25 days post eclosion on females from ten laboratory populations ofDrosophila melanogaster. The females assayed came from one of two treatments; they were maintained as adults on either regular or urea-supplemented food. We found that exposure to urea-supplemented food inhibited fecundity, relative to the levels exhibited on regular food, regardless of whether the urea was present in the assay medium, or in the medium on which the flies were maintained over the course of the experiment, thereby suggesting that urea has both a long-term (possibly physiological) as well as a short-term (possibly behavioural) inhibitory effect on fecundity ofDrosophila females. We also tested and ruled out the hypothesis that prior yeasting could ameliorate the inhibitory effect of urea in the assay medium on fecundity, as this was a possible explanation of why flies given a choice between regular and urea-supplemented food did not exhibit a preference for regular food in a previous study.     

Short- and long-term effects of vinblastine on the rat adrenal medulla

Summary The effects of a single high dose (10mg/kg) of vinblastine (vb) sulfate (Velbe, Lilly) on the ultrastructure, catecholamine (CA) content and activity of CA-synthesizing enzymes of the rat adrenal medulla were studied for up to 120h after intravenous injection of the drug.By 1 h, microtubules were virtually absent from chromaffin cells and preganglionic cholinergic axons, and typical paracrystals had appeared inside the nerve fibers. By 16h microtubules were completely reconstituted and paracrystals had disappeared. From 16h onwards, there was an increasing depletion of storage granules from adrenaline (A) — producing cells, which coincided with biochemical determinations showing a reduction of adrenal A to about 40 % of control levels by 48 h, with noradrenaline (NA) remaining in the range of controls. Both A- and NA-storing cells showed an extensive proliferation of the rough endoplasmic reticulum (ER). Vb caused a marked increase in tyrosine hydroxylase (TH; +113%) and dopamine -hydroxylase (DBH; +82%) activities after 48 h. Splanchnicotomy completely abolished the vb-mediated increase in TH and DBH activities. A smaller increase (+ 47 %) in enzyme activity was observed with phenylethanolamine N-methyltransferase (PNMT). Vb (10^–5M) had no apparent effect on granule content and the amount of rough ER in chromaffin cells, which were cultured for 48 h.The results demonstrate that a single high dose of vb has relatively little short-term effects on the rat adrenal medulla, but causes drastic long-term changes in CA-content and enzyme activities that are mediated by the preganglionic nerves. These changes could be interpreted as an effort to compensate for a loss of CA-stores in peripheral adrenergic nerves (cf. Cheney et al., 1973). The differential long-term effect of vb on adrenal NA and A might be due to the lower induction of PNMT as compared to TH and DBH activities and/or to a preferential release of A versus NA, which may occur at high frequencies of stimulation of the splanchnic nerves.Supported by grants from the Deutsche ForschungsgemeinschaftDedicated to Professor G. Petry in honor of his 65th birthday     

Sphingolipid therapy in myocardial ischemia-reperfusion injury

Sphingolipids are known to play a significant physiological role in cell growth, cell differentiation, and critical signal transduction pathways. Recent studies have demonstrated a significant role of sphingolipids and their metabolites in the pathogenesis of myocardial ischemia-reperfusion injury. Our laboratory has investigated the cytoprotective effects of N,N,N-trimethylsphingosine chloride (TMS), a stable N-methylated synthetic sphingolipid analogue on myocardial and hepatic ischemia-reperfusion injury in clinically relevant in vivo murine models of ischemia-reperfusion injury. TMS administered intravenously at the onset of ischemia reduced myocardial infarct size in the wild-type and obese (ob/ob) mice. Following myocardial I/R, there was an improvement in cardiac function in the wild-type mice. Additionally, TMS also decreased serum liver enzymes following hepatic I/R in wild-type mice. The cytoprotective effects did not extend to the ob/ob mice following hepatic I/R or to the db/db mice following both myocardial and hepatic I/R. Our data suggest that although TMS is cytoprotective following I/R in normal animals, the cytoprotective actions of TMS are largely attenuated in obese and diabetic animals which may be due to altered signaling mechanisms in these animal models. Here we review the therapeutic role of TMS and other sphingolipids in the pathogenesis of myocardial ischemia-reperfusion injury and their possible mechanisms of cardioprotection.     

短期和长期运动预适应对力竭大鼠心肌损伤的保护作用

目的：研究短期和长期运动预适应对心肌细胞凋亡保护中发挥的作用及机制。方法：48只雄性SD大鼠随机分为对照组（C）、力竭组（E）、短期运动预适应组（S-EP）、长期运动预适应组（L-EP）。短期和长期运动预适应分别进行3 d和3周的反复间歇游泳训练方案。光镜下观察心肌细胞的结构改变;ELISA方法检测血清中缺血修饰白蛋白（IMA）、磷酸肌酸同工酶（CK-MB）含量;实时荧光定量PCR和Western blot方法检测心肌组织中TNF-α、Caspase-8、Caspase-3基因和蛋白表达;采用DNA原位末端标记（TUNEL）法观察心肌细胞的凋亡情况。结果：与C组相比,E组心肌细胞损伤严重,血清IMA、CK-MB含量及心肌组织中TNF-α、Caspase-8、Caspase-3 mRNA和蛋白表达升高（P<0.05）;与E组相比,S-EP组血清CK-MB及心肌TNF-α、Caspase-8mRNA明显降低（P<0.05）,而蛋白表达无统计学差异,血清IMA及Caspase-3 mRNA和蛋白均下降不明显,无统计学意义（P>0.05）,L-EP组血清IMA、CK-MB含量及心肌TNF-α、Caspase-8、Caspase-3 mRNA及蛋白明显降低,有统计学意义（P<0.05）;与S-EP组相比,L-EP组血清IMA、CK-MB含量及TNF-α、Caspase-8、Caspase-3 mRNA和蛋白明显下降,有统计学意义（P<0.05）。E组心肌细胞凋亡明显,S-EP组和L-EP组均能抑制凋亡,且L-EP组与S-EP组相比心肌凋亡明显减少。结论：短期和长期运动预适应均可减轻力竭后的心肌损伤,但短期运动预适应并未改变Caspase蛋白酶的表达,长期运动预适应明显抑制Caspase-8、3 mRNA表达,减少蛋白合成,从而发挥心肌保护效应,故长期运动预适应在抑制心肌细胞凋亡方面较短期运动预适应更强。     

Anticancer activity of 3-O-acyl and alkyl-(-)-epicatechin derivatives

By changing the structure or replacing the gallate group of (-)-ECG, 3-O-acyl and alkyl-(-)-epicatechin derivatives were synthesized to be screen as anticancer agents using the MTT assay in vitro against cancer cell lines (PC3, SKOV3, U373MG). 3-O-Acyl and alkyl-(-)-epicatechin derivatives (4-25) exhibited better anticancer activity than (-)-ECG and specially, compounds 6-8, 17-19, which were modified aliphatic chains with moderate sizes (C8-C12) showed strong anticancer activity (IC50=6.4-31.2 microM). The introduction of an alkyloxy group on 3-O-hydroxyl instead of an acyloxy group significantly enhanced inhibitory activity. Consequently, the compound that showed the most potency as anticancer agents were 3-O-decyl-(-)-epicatechin (18) (IC50=8.9, 7.9, 6.4 microM against PC3, SKOV3, U373MG, respectively), which modified the appropriate lipophilic group on the C-3 hydroxyl as an alkyloxy group.     

Effects of natural antioxidant Ginkgo biloba extract (EGB 761) on myocardial ischemia-reperfusion injury

Recently, it was reported that Ginkgo biloba extract (EGb 761), which is known to have antioxidant properties, also has antiarrhythmic effects on cardiac reperfusion-induced arrhythmias. In the present study, effects of EGb 761 on cardiac ischemia-reperfusion injury were investigated from the point of view of recovery of mechanical function as well as the endogenous antioxidant status of ascorbate. Isolated rat hearts were perfused using the Langendorff technique, and 40 min of global ischemia were followed by 20 min of reperfusion. EGb 761 improved cardiac mechanical recovery and suppressed the leakage of lactate dehydrogenase (LDH) during reperfusion. Furthermore, EGb 761 diminished the decrease of myocardial ascorbate content after 40 min of ischemia and 20 min of reperfusion. Interestingly, EGb 761 also suppressed the increase of dehydroascorbate. These results indicate that EGb 761 protects against cardiac ischemia-reperfusion injury and suggest that the protective effects of EGb 761 depend on its antioxidant properties.     

15-F(2t)-isoprostane exacerbates myocardial ischemia-reperfusion injury of isolated rat hearts

Reactive oxygen species induce formation of 15-F(2t)-isoprostane (15-F(2t)-IsoP), a specific marker of in vivo lipid peroxidation, which is increased after myocardial ischemia and during the subsequent reperfusion. 15-F(2t)-IsoP possesses potent bioactivity under pathophysiological conditions. However, it remains unknown whether 15-F(2t)-IsoP, by itself, can influence myocardial ischemia-reperfusion injury (IRI). Adult rat hearts were perfused by the Langendorff technique with Krebs-Henseleit (KH) solution at a constant flow rate of 10 ml/min. 15-F(2t)-IsoP (100 nM), SQ-29548 (1 microM, SQ), a thromboxane receptor antagonist that can abolish the vasoconstrictor effect of 15-F(2t)-IsoP, 15-F(2t)-IsoP + SQ in KH, or KH alone (vehicle control) was applied for 10 min before induction of 40 min of global ischemia followed by 60 min of reperfusion. During ischemia, saline (control), 15-F(2t)-IsoP, 15-F(2t)-IsoP + SQ, or SQ in saline was perfused through the aorta at 60 microl/min. 15-F(2t)-IsoP, 15-F(2t)-IsoP + SQ, or SQ in KH was infused during the first 15 min of reperfusion. Coronary effluent endothelin-1 concentrations were significantly higher in the group treated with 15-F(2t)-IsoP than in the control group during ischemia and also in the later phase of reperfusion (P < 0.05). Infusion of 15-F(2t)-IsoP increased release of cardiac-specific creatine kinase, reduced cardiac contractility during reperfusion, and increased myocardial infarct size relative to the control group. SQ abolished the deleterious effects of 15-F(2t)-IsoP. 15-F(2t)-IsoP exacerbates myocardial IRI and may, therefore, act as a mediator of IRI. 15-F(2t)-IsoP-induced endothelin-1 production during cardiac reperfusion may represent a mechanism underlying the deleterious actions of 15-F(2t)-IsoP.     

Short- and long-term effects of silver nanoparticles on human microvascular endothelial cells

AIM: To study the response to silver nanoparticles (Ag NP) of human microvascular endothelial cells, protagonists of angiogenesis.METHODS: We cultured human microvascular endothelial cells and endothelial colony-forming cells in their corresponding growth medium. Stock solutions of Ag NP were prepared in culture medium and sonicated before use. They were added at different concentrations and for different times to culture media. The toxicity of Ag NP was investigated by measuring the reduction of yellow tetrazolium salt to dark purple formazan (MTT assay) at 575 nm. After staining with trypan blue, cell proliferation was assessed by counting viable cells. The lactate dehydrogenase leakage assay was performed on culture media by following the oxidation of NADH to NAD+ and monitoring the reaction kinetically at 340 nm. Reactive oxygen species production was quantified using 2’-7’-dichlorofluorescein diacetate. The alkaline comet assay was performed after mixing the cells with low melting-point agarose. Electrophoresis was then conducted and the samples were stained with ethidium bromide and analyzed with a fluorescence microscope.RESULTS: Ag NP are cytotoxic in a dose and time dependent fashion for HMEC. At high concentrations, Ag NP determine loss of membrane integrity as demonstrated by the increased activity of lactate dehydrogenase in the culture medium. Ag NP rapidly stimulate the formation of free radicals. However, pre-incubation with Trolox, apocynin, or N-acetyl-L-cysteine, antioxidants which have different structure and act through different mechanisms, is not sufficient to prevent cytotoxicity. Ag NP also induce DNA damage dose-dependently, as shown by comet assay. When exposed to sublethal concentrations of Ag NP for long times, the cells remain viable but are growth retarded. Interestingly, removal of Ag NP partially rescues cell growth. Also genotoxicity is reversible upon removal of Ag NP from culture medium, suggesting that no permanent modifications occur. It is noteworthy that Ag NP are cytotoxic and genotoxic also for endothelial progenitors, in particular for endothelial colony-forming cells, which participate to angiogenesis.CONCLUSION: Silver nanoparticles are cytotoxic and genotoxic for human microvascular endothelial cells and might become a useful tool to control excessive angiogenesis.     

Short- and long-term freezing effects in a coastal (Lobaria virens) versus a widespread lichen (L. pulmonaria)

Lichens are considered freezing tolerant, although few species have been tested. Growth, a robust measure of fitness integrating processes in all partners of a lichen thallus, has not yet been used as a viability measure after freezing. We compared relative growth rates (RGR) after freezing with short-term viability measures of photo- and mycobiont functions in the coastal Lobaria virens and the widespread L. pulmonaria to test the hypothesis that low temperature shapes the coastal distribution of L. virens. Hydrated thalli from sympatric populations were subjected to freezing at −10, −20 and −40 °C for 5 h. The rate of cooling and subsequent warming was 5 °C h⁻¹. Short-term viability measures of photobiont (maximal photosystem II efficiency, effective PSII yield) and mycobiont viability (conductivity index), as well as subsequent RGR, were assessed. The exotherms showed that L. virens froze at −3 °C; L. pulmonaria, at −4 °C. Freezing significantly impaired short-term viability measures of both photo- and mycobiont, particularly in the coastal species. Lobaria pulmonaria grew 2.1 times faster than L. virens, but the short-term damage after one freezing event did not affect the long-term RGR in any species. Thereby, short-term responses were impaired by freezing, long-term responses were not. While the lacking RGR-responses to freezing suggest that freezing tolerance does not shape the coastal distribution of L. virens, the significant reported adverse short-term effects in L. virens may be aggravated by repeated freezing-thawing cycles in cold winters. In such a perspective, repeated freezing may eventually lead to reduced long-term fitness in L. virens.     

Investigation of the antibacterial activity of 3-O-octanoyl-(-)-epicatechin

Aims: To measure antibacterial activity of the semi-synthetic flavonoid 3-O-octanoyl-(–)-epicatechin and investigate the mechanism of action. Methods and Results: MICs determined by the broth microdilution method were 50 μg ml⁻¹ for β-lactam sensitive and resistant Staphylococcus aureus, and 100 μg ml⁻¹ for vancomycin sensitive and resistant enterococci. In time-kill studies, 100 μg ml⁻¹ 3-O-octanoyl-(–)-epicatechin reduced colony forming unit numbers of antibiotic sensitive and methicillin-resistant Staph. aureus below detectable levels within 120 min. Bacterial aggregation was not observed when cells exposed to 3-O-octanoyl-(–)-epicatechin were examined by light microscopy. It was also shown that 50 μg ml⁻¹ 3-O-octanoyl-(–)-epicatechin is capable of reducing colony forming unit numbers of high cell density Staph. aureus populations by 80-fold within 60 min incubation, and inducing leakage of 50% of their internal potassium within just 10 min. Conclusions: 3-O-Octanoyl-(–)-epicatechin is active against Gram-positive bacteria, has bactericidal activity against both antibiotic sensitive and resistant strains, and is likely to exert its primary antibacterial effect by damaging the cytoplasmic membrane. Significance and Impact of the Study: 3-O-Octanoyl-(–)-epicatechin has significant antibacterial activity and additional structural modification and/or formulation studies may allow this to be potentiated.     

Effect of aminoguanidine on ischemia-reperfusion induced myocardial injury in rats

Myocardial ischemia-reperfusion (MI/R) has been implicated in the induction of inducible nitric oxide synthase (iNOS) that leads to increase production of nitric oxide (NO). Recently, excessive production of NO has been involved in causing myocardial injury. In our in vivo model, we examined the effects of aminoguanidine (AMG), a known iNOS inhibitor, on percentage infarct size in anaesthetized rats. A total of 14 rats were equally divided into two groups (n = 7 in each group). To produce myocardial necrosis, the left main coronary artery was occluded for 30 min, followed by 120 min of reperfusion, in anesthetized rats. AMG (200 mg kg⁻¹) was given intravenously 10 min before occlusion. The volume of infarct size and the risk zone were determined by planimentry of each tracing and multiplying by the slice thickness. Infarct size was normalized by expressing it as a percentage of the area at risk. Hemodynamic parameters were measured via the left carotid artery. Compared to MI/R group, whereas AMG administration elevated mean arterial blood pressure, statistically reduced the myocardial infarct size (21± 1 and 14± 4%, respectively) and infract size/risk zone (53± 3 and 37± 5%, respectively) in rat model of ischemia-reperfusion. In conclusion, this study indicates that iNOS inhibitor, AMG, show reduction in NO’s side effect in I/R injury.     

Comparative effects of ischemic pre and postconditioning on ischemia-reperfusion injury in spontaneously hypertensive rats (SHR)

Brief episodes of myocardial ischemia-reperfusion applied early in reperfusion may attenuate the reperfusion injury, strategy called ischemic postconditioning (IPO). Our objective was to examine the effects of IPO compared with ischemic preconditioning (IP) on postischemic myocardial dysfunction in spontaneously hypertensive rats (SHR). Isolated hearts from SHR and normotensive WKY rats were subjected to the following protocols: (1) Ischemic control (IC): global ischemia 20 min (GI20) and reperfusion 30 min (R). (2) IPO: three cycles of R30sec–IG30sec at the onset of R; (3) IP: a cycle of IG5–R10 previous to GI20, (4) IPO in the presence of chelerythrine, an inhibitor of protein kinase C (PKC). Systolic and diastolic function were assessed through developed pressure (LVDP) and end diastolic pressure (LVEDP), respectively. Lipid peroxidation was estimated by thiobarbituric reactive substance (TBARS) concentration. IPO significantly improved postischemic dysfunction. At the end of R, LVDP recovered to 87 ± 7% in WKY and 94 ± 7% in SHR vs. 55 ± 11% and 58 ± 12% in IC hearts. LVEDP reached values of 24 ± 6 mmHg for WKY and 24 ± 3 mmHg for SHR vs. 40 ± 8 and 42 ± 5 mmHg in IC hearts. Similar protection was achieved by IP. TBARS contents of SHR hearts were significantly diminished by IP and IPO. PKC inhibition aborted the protection of myocardial function and attenuated the diminution of lipid peroxidation conferred by IPO. These data show that IPO was as effective as IP in improving the postischemic dysfunction of hearts from SHR hearts, and that this cardioprotection appears to be associated with a diminution of ROS-induced damage involving the PKC activation.