Biotechnological approach of improving plant salt tolerance using antioxidants as markers

Salt stress causes multifarious adverse effects in plants. Of them, production of reactive oxygen species (ROS) is a common phenomenon. These ROS are highly reactive because they can interact with a number of cellular molecules and metabolites thereby leading to a number of destructive processes causing cellular damage. Plants possess to a variable extent antioxidant metabolites, enzymes and non-enzymes, that have the ability to detoxify ROS. In the present review, the emphasis of discussion has been on understanding the role of different antioxidants in plants defense against oxidative stress caused by salt stress. The role of different antioxidants as potential selection criteria for improving plant salt tolerance has been critically discussed. With the advances in molecular biology and availability of advanced genetic tools considerable progress has been made in the past two decades in improving salt-induced oxidative stress tolerance in plants by developing transgenic lines with altered levels of antioxidants of different crops. The potential of this approach in counteracting stress-induced oxidative stress has been discussed at length in this review.

Differential cardiovascular effects of calcium channel blocking agents: potential mechanisms

The three major calcium channel blocking agents, diltiazem, nifedipine and verapamil, inhibit calcium entry into excitable cells. Despite this apparent common action at the cell membrane, these drugs produce quantitative and frequently qualitative differences in cardiovascular variables (for example, heart rate, atrioventricular [A-V] conduction and myocardial inotropic state) when evaluated at equieffective vasodilator doses. All three drugs increase coronary blood flow in a dose-dependent fashion (nifedipine greater than diltiazem = verapamil), and produce a negative inotropic effect in vitro in isolated atria and ventricles, also in a dose-dependent manner (verapamil greater than nifedipine greater than diltiazem). However, in conscious dogs nifedipine increases, verapamil decreases and diltiazem has little effect on the inotropic state. A-V conduction is slowed by diltiazem and verapamil but not by nifedipine in anesthetized dogs and in conscious dogs as judged from the P-R interval in the electrocardiogram. Heart rate is slowed in pentobarbital-anesthetized animals but is accelerated in conscious dogs (nifedipine greater than verapamil greater than diltiazem). Nifedipine also appears to interfere significantly with the arterial baroreceptor reflex by an apparent vagolytic action that is less evident with diltiazem and verapamil. Diltiazem, and possibly verapamil and nifedipine as well, appears to retard myocardial damage that accompanies ischemia. The mechanisms and sites of action of these drugs are presumed to be at the cell membrane; however, intracellular sites may also be involved.

Activation of mitochondrial ATP-sensitive K(+) channel for cardiac protection against ischemic injury is dependent on protein kinase C activity

Protein kinase C (PKC) is involved in the second messenger signaling cascade during ischemic and Ca(2+) preconditioning. Given that the pharmacological activation of mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channels also mimics preconditioning, the mechanisms linking PKC activation and mitoK(ATP) channels remain to be established. We hypothesize that PKC activity is important for the opening of the mitoK(ATP) channel. To examine this, a specific opener of the mitoK(ATP) channel, diazoxide, was used in conjunction with subcellular distribution of PKC in a model of ischemia/reperfusion (I/R). Langendorff-perfused rat hearts were subjected to 40-minute ischemia followed by 30-minute reperfusion. Effects of activation of the mitoK(ATP) channel and other interventions on functional, biochemical, and pathological changes in ischemic hearts were assessed. In hearts treated with diazoxide, left ventricular end-diastolic pressure and coronary flow were significantly improved after I/R; lactate dehydrogenase release was also significantly decreased. The morphology was well preserved in diazoxide-treated hearts compared with nontreated ischemic control hearts. The salutary effects of diazoxide on the ischemic injury were similar to those of Ca(2+) preconditioning. Administration of sodium 5-hydroxydecanoate, an effective blocker of the mitoK(ATP) channel, or chelerythrine or calphostin C, an inhibitor of PKC, during diazoxide pretreatment or during continuous presence of diazoxide in the ischemic period, completely abolished the beneficial effects of the diazoxide on the I/R injury. Blockade of Ca(2+) entry during diazoxide treatment by inhibiting the L-type Ca(2+) channel with verapamil also completely reversed the beneficial effect of diazoxide during I/R. PKC-alpha was translocated to sarcolemma, whereas PKC-delta was translocated to the mitochondria and intercalated disc, and PKC-epsilon was translocated to the intercalated disc of the diazoxide-pretreated hearts. Colocalization studies for mitochondrial distribution with tetramethylrhodamine ethyl ester (TMRE) and PKC isoforms by immunoconfocal microscopy revealed that PKC-delta antibody specifically stained the mitochondria. ATP was significantly increased in the diazoxide-treated hearts. Moreover, the data suggest that activation and translocation of PKC to mitochondria appear to be important for the protection mediated by mitoK(ATP) channel.

Effects by doxorubicin on the myocardium are mediated by oxygen free radicals

We hypothesized that doxorubicin (DOX) induces cardiotoxicity of myocardium via oxygen radicals. The present study is aimed at examining the membrane alterations by oxygen radicals generated by DOX in adult rats and cultured neonatal myocytes. Our results showed that DOX 1) decreased beta-adrenoceptor (BAR) density in the cell membrane, 2) increased the membrane permeability of cultured neonatal rat myocytes and 3) altered the ultrastructure of myofibrils and subplasmalemmal actin networks. These effects were reproducible by exogenous hydrogen peroxide. The antioxidant melatonin (MLT) inhibited enzyme leakage and peroxidation in a concentration-dependent manner. It is concluded that DOX induces cardiotoxicity through lipid peroxidation and melatonin is an effective antioxidant against the reactive oxygen intermediates generated by DOX.

Direct evidence that initial oxidative stress triggered by preconditioning contributes to second window of protection by endogenous antioxidant enzyme in myocytes

BACKGROUND

We tested the hypothesis that late preconditioning is associated with increased antioxidant enzyme activity induced by initial oxidative stress.

METHODS AND RESULTS

Isolated rat myocytes were preconditioned either with two cycles of 5 minutes of anoxia and 5 minutes of reoxygenation or with exogenous superoxide anion (O2-) generated by reaction of xanthine oxidase with xanthine. Myocytes were allowed to recover for 60 minutes or 24 hours, after which they were subjected to 60 minutes of anoxia and 60 minutes of reoxygenation. After 60 minutes or 24 hours, the protection was evidenced by decreased O2- production, increased Mn superoxide dismutase (Mn-SOD) activity, increased call viability, decreased LDH release, reduced malondialdehyde formation, high-energy phosphate preservation, and improved call morphology in preconditioned and O2(-)-treated myocytes. Immediately after treatment with O2- or repetitive, brief anoxia, O2- production was increased in myocytes. Longer anoxia resulted in loss of Mn-SOD activity in anoxic controls 24 hours later, whereas it was significantly increased in preconditioned and O2- -treated myocytes. O2- production was inhibited in preconditioned and O2(-)-myocytes. Myocytes treated with Mn-SOD during short, intermittent anoxia exhibited decreased activity of Mn-SOD and increased O2- production 24 hours later. Mn-SOD activity in late preconditioning was considerably higher than that in classic preconditioning.

CONCLUSIONS

These results suggest that a burst of oxygen free radicals generated during the initial periods of brief, repetitive anoxia increases myocardial antioxidant activity 24 hours later and that it contributes to the late cardioprotective effect of preconditioning.

Role of protein kinase C in mitochondrial KATP channel-mediated protection against Ca2+ overload injury in rat myocardium

Growing evidence exists that ATP-sensitive mitochondrial potassium channels (MitoKATP channel) are a major contributor to the cardiac protection against ischemia. Given the importance of mitochondria in the cardiac cell, we tested whether the potent and specific opener of the MitoKATP channel diazoxide attenuates the lethal injury associated with Ca2+overload. The specific aims of this study were to test whether protection by diazoxide is mediated by MitoKATP channels; whether diazoxide mimics the effects of Ca2+ preconditioning; and whether diazoxide reduces Ca2+ paradox (PD) injury via protein kinase C (PKC) signaling pathways. Langendorff-perfused rat hearts were subjected to the Ca2+ PD (10 minutes of Ca2+ depletion followed by 10 minutes of Ca2+ repletion). The effects of the MitoKATP channel and other interventions on functional, biochemical, and pathological changes in hearts subjected to Ca2+ PD were assessed. In hearts treated with 80 micromol/L diazoxide, left ventricular end-diastolic pressure and coronary flow were significantly preserved after Ca2+ PD; peak lactate dehydrogenase release was also significantly decreased, although ATP content was less depleted. The cellular structures were well preserved, including mitochondria and intercalated disks in diazoxide-treated hearts compared with nontreated Ca2+ PD hearts. The salutary effects of diazoxide on the Ca2+ PD injury were similar to those in hearts that underwent Ca2+ preconditioning or pretreatment with phorbol 12-myristate 13-acetate before Ca2+ PD. The addition of sodium 5-hydroxydecanoate, a specific MitoKATP channel inhibitor, or chelerythrine chloride, a PKC inhibitor, during diazoxide pretreatment completely abolished the beneficial effects of diazoxide on the Ca2+ PD. Blockade of Ca2+ entry during diazoxide treatment by inhibiting L-type Ca2+ channel with verapamil or nifedipine also completely reversed the beneficial effects of diazoxide on the Ca2+ PD. PKC-delta was translocated to the mitochondria, intercalated disks, and nuclei of myocytes in diazoxide-pretreated hearts, and PKC-alpha and PKC-epsilon were translocated to sarcolemma and intercalated disks, respectively. This study suggests that the effect of the MitoKATP channel is mediated by PKC-mediated signaling pathway.

Activation of mitochondrial K(ATP) channel elicits late preconditioning against myocardial infarction via protein kinase C signaling pathway

Activation of mitochondrial K(ATP) (mitoK(ATP)) channel induces acute ischemic preconditioning (PC) against ischemic injury. The ability of this channel to elicit late PC remains unknown. The present study tests the hypothesis that stimulation of mitoK(ATP) channel induces late PC via the protein kinase C (PKC) signaling pathway. Rats were subjected to 30 minutes of regional ischemia and 120 minutes of reperfusion (I/R). In other groups, rats were pretreated with diazoxide, a specific opener of the mitoK(ATP) channel (7 mg/kg, IV), 12, 24, 48, and 72 hours before they were subjected to I/R. A maximum reduction in infarct size was observed after 24 hours (33.3+/-2.2% versus I/R group, 62.1 +/-2.4%). Pretreatment with diazoxide did not reduce the infarct size significantly after 12, 48, and 72 hours (50.2+/-4.3%, 50.5+/-4.6%, and 58.2+/-4.9%) compared with the I/R group. The protection was blocked with 5-hydroxydecanoic acid (5-HD, 5 mg/kg IV), a relatively selective mitoK(ATP) channel blocker (56.5+/-2.7%), and chelerythrine (5 mg/kg IV), an effective PKC inhibitor (57.1+/-3.4%) administered either on the first day before diazoxide pretreatment or 10 minutes before I/R on the second day. Cell necrosis was decreased by approximately 50% in the diazoxide preconditioned hearts compared with control I/R hearts. Cell death by apoptosis was also significantly decreased in diazoxide pretreated hearts (3.2%) as compared with I/R (11.3%). In conclusion, activation of mitoK(ATP) channel with diazoxide produces late PC against reperfusion injury. The effect of mitoK(ATP) channel appears to be dependent on the PKC-mediated signal pathway.

Connective tissue changes in early ischemia of porcine myocardium: an ultrastructural study

Scanning electron microscopy and transmission electron microscopy were used together with tannic acid and ruthenium-red staining to examine connective tissue damage caused by acute myocardial ischemia for 20, 40 and 120 min in pig hearts. The microsphere blood flow technique revealed that blood flow was approximately 0.02 ml/min/g in inner, middle and outer thirds of the ischemic zone. After 20 min of occlusion of the left anterior descending coronary artery, the collagen network and microfilaments became irregularly arranged. After 40 min of occlusion, ruthenium-red positive glycoprotein material around the collagen fibrils and elastin began to disappear. After 2 h occlusion, the collagen fibrils and microfilaments had separated from the basement membrane. Collagen fibrils, elastic fibers, and microfilaments were broken down and were found in decreased quantities. These results have revealed that the connective tissue remains intact during the first 20 min of coronary occlusion despite zero blood flow and mild cellular changes but does undergo prominent alterations after 40 min of occlusion.

Swimming training lowers the resting blood pressure in individuals with hypertension

BACKGROUND

Despite the fact that swimming is often recommended for the prevention and treatment of hypertension, no study has examined the potential efficacy of regular swimming exercise for lowering the blood pressure in hypertensive humans.

OBJECTIVE

To test the hypothesis that regular swimming exercise lowers the resting blood pressure.

DESIGN

A 10-week closely supervised swimming training program compared with a non-exercising control group.

PATIENTS

Eighteen previously sedentary men and women [aged 48 +/- 2 years (mean +/- SEM)] with stage 1 or 2 essential hypertension.

RESULTS

The resting heart rated, an index of cardiovascular adaptation, decreased in the swimming training group from 81 +/- 4 to 71 +/- 3 beats/min (P < 0.01). The body mass and body fat percentage did not show statistically significant changes. The systolic blood pressure of patients in the seated position fell significantly (P < 0.05) from 150 +/- 5 to 144 +/- 4 mmHg. The seated diastolic blood pressure did not change significantly. A similar magnitude of reductions in systolic blood pressure (P < 0.05) was also found in patients in the supine position. No significant changes in plasma catecholamine concentrations, casual forearm vascular resistance, plasma volume and blood volume were observed. There were no significant changes in any of these variables in the control group.

CONCLUSION

Swimming training elicits significant reductions in arterial blood pressure at rest in individuals with hypertension. This is a clinically important finding since swimming can be a highly useful alternative to land-based exercises for hypertensive patients with obesity, exercise-induced asthma, or orthopedic injuries.

Ca2+ as a mediator of ischemic preconditioning

We tested the hypothesis that elevation of [Ca2+]i during ischemic preconditioning (IPC) stimulates protein kinase C (PKC), which confers the protection against the ischemic injury. Langendorff-perfused rat hearts were subjected to 40-minute global ischemia followed by 30-minute reperfusion (I/R). In preconditioned groups, hearts were subjected to either IPC, consisting of 5-minute global ischemia and 10-minute reperfusion, or high-Ca2+ preconditioning (HCPC), ie, the 5-minute perfusion of higher Ca2+ perfusate (2.3 mmol/L Ca2+) followed by 10-minute perfusion of normal perfusate (1.8 mmol/L Ca2+), and then were subjected to I/R. A significant functional recovery and decreased lactate dehydrogenase release were observed in HCPC and IPC hearts compared with ischemic control hearts. ATP contents of preconditioned hearts were significantly higher than those of the ischemic control hearts. The cell structure in preconditioned hearts was preserved better than that in the ischemic control hearts. Furthermore, the activation and translocation of PKC from cytoplasm to sarcolemma were observed in the preconditioned hearts. Verapamil administered during IPC significantly attenuated the salutary effects of IPC. Administration of chelerythrine, a specific PKC inhibitor, completely abolished the HCPC- and IPC-induced cardioprotection. The translocation of PKC by IPC was blocked by verapamil or chelerythrine. Immunohistochemical study using rabbit polyclonal antibody against PKC isoforms indicated that stress induced by IPC or HCPC evoked the translocation of PKC alpha and PKC delta to the cell membrane. Translocation of PKC isoforms was attenuated by the treatment with verapamil or chelerythrine. These results demonstrate that (1) a transient increase in [Ca2+]i during IPC is an important trigger for the activation of PKC, which is responsible for cardioprotection; (2) the elevation of [Ca2+]i during IPC, at least partly, resulted from Ca2+ entry via voltage-dependent Ca2+ channel; and (3) activation and translocation of PKC alpha and PKC delta occur during IPC and HCPC and may be important in preconditioning.

Downregulation of protein kinase C inhibits activation of mitochondrial K(ATP) channels by diazoxide

BACKGROUND

The mitochondrial K(ATP) (mitoK(ATP)) channel has been shown to confer short- and long-term cardioprotection against prolonged ischemia via protein kinase C (PKC) signaling pathways. However, the exact association between PKC or its isoforms and mitoK(ATP) channels has not yet been clarified. The present study tested the hypothesis that the activity and translocation of PKC to the mitochondria are important for cardiac protection elicited by mitoK(ATP) channels. Methods and Results-PKC was downregulated by prolonged (24-hour) treatment with phorbol 12-myristate 13-acetate (4 microgram/kg body weight) before subsequent experiments in rats. Langendorff-perfused rat hearts were subjected to 40 minutes of ischemia followed by 30 minutes of reperfusion. Effects of PKC downregulation on the activation of mitoK(ATP) channels and other interventions on hemodynamic, biochemical, and pathological changes were assessed. Subcellular localization of PKC isoforms by Western blot analysis and immunocytochemistry demonstrated that PKC-alpha and PKC-delta were translocated to the sarcolemma and that PKC-delta was translocated to the mitochondria after diazoxide treatment. In hearts treated with diazoxide (80 micromol/L), a significant improvement in cardiac function and an attenuation of cell injury were observed. In PKC-downregulated hearts, protection was abolished because mitoK(ATP) channels could not be activated by diazoxide.

CONCLUSIONS

These data suggest that PKC activation is required for the opening of mitoK(ATP) channels during protection against ischemia and that this effect is linked to isoform-specific translocation of PKC-delta to the mitochondria.

Mitochondrial K(ATP) channel as an end effector of cardioprotection during late preconditioning: triggering role of nitric oxide

Nitric oxide (NO) has been implicated in the "second-window" of ischemic preconditioning (PC). However, the identity of the end effector after initiation of preconditioning by NO is not known. It is likely that NO is involved in opening of mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels. We hypothesized that NO is an important trigger for the opening of mitoK(ATP) channels in the late phase of preconditioning and inducible nitric oxide synthase (iNOS) up-regulation via NF kappa B plays a critical role in diazoxide-induced cardioprotection. To examine this, diazoxide (7 mg/kg) was administered to wild-type (WT) mice and mice lacking the gene 24 hours before 40 minutes of global ischemia. Hearts were perfused in a Langendorff mode and effects of activation of mitoK(ATP) channel and other interventions on functional, biochemical and pathological changes in ischemic hearts were assessed. In hearts from WT mice treated diazoxide, left-ventricular-developed pressure, end-diastolic pressure and coronary flow were significantly improved after ischemia/reperfusion (I/R); lactate dehydrogenase (LDH) release was also significantly decreased, while ATP contents were significantly higher. Administration of 5-HD, a specific blocker of mitoK(ATP) channel or l -NAME, an inhibitor of iNOS before I/R, during diazoxide-pretreatment completely blocked the late cardioprotection against ischemia. Late cardioprotection was also blocked by inhibition of either PKC- delta by rottlerin or NF kappa B by DDTC before diazoxide pretreatment. Diazoxide pretreatment significantly increased nuclear translocation of p65 which was blocked by protein kinase C (PKC) or nitric oxide synthase (NOS) inhibition. Diazoxide was totally inefffective in iNOS knockout mice. These results suggest that diazoxide activates NF kappa B via PKC signaling pathway and that leads to iNOS up-regulation after 24 hours. NO which is generated upon ischemic stress triggers the opening of mitoK(ATP)channel as an end effector of cardioprotection during late PC.

Improved functional recovery of ischemic rat hearts due to singlet oxygen scavengers histidine and carnosine

There is increasing evidence that reactive oxygen species (ROS) contribute to post-ischemic reperfusion injury, but determination of the specific ROS involved has proven elusive. In the present study electron paramagnetic resonance (EPR) spectroscopy was used in vitro to measure the relative quenching of singlet oxygen (1O2) by histidine and carnosine (beta-alanyl-L-histidine) utilizing the hindered secondary amine 2,2,6,6-tetramethyl-4-piperidone HCl (4-oxo-TEMP). The relative effect of histidine and carnosine on functional recovery of isolated perfused rat hearts was also studied. Functional recovery was measured by left ventricular developed pressure (LVDP), first derivative of left ventricular pressure (dP/dt), heart rate (HR) and coronary flow (CF). EPR measurements and Stern-Volmer plots showed that 400 microM carnosine quenched 1O2 twice as effectively as equimolar histidine in vitro. Moreover, 10 mM histidine improved functional recovery of isolated rat hearts significantly more than 1 mM histidine. Furthermore, 1 mM carnosine improved functional recovery significantly more than equimolar histidine and as effectively as 10 mM histidine. Experiments with 1 mM mannitol, a known hydroxyl radical scavenger, did not show an improvement in functional recovery relative to control hearts, thereby decreasing the likelihood that hydroxyl radicals are the major damaging species. On the other hand, the correlation between improved functional recovery of isolated rat hearts with histidine and carnosine and their relative 1O2 quenching effectiveness in vitro provides indirect evidence for 1O2 as ROS participating in reperfusion injury.

Transmural cellular damage and blood flow distribution in early ischemia in pig hearts

Transmural histological changes were determined morphometrically in the left ventricular free wall of 20 pigs after ligation of distal left anterior descending coronary artery for 10, 20, 40, and 120 minutes. Hemodynamics were recorded and regional blood flow distribution was measured in the ischemic zone. Coronary occlusion produced regional transmural ischemia without producing significant systemic hemodynamic change. The microsphere blood flow technique revealed that blood flow was less than 0.05 ml/min per g in all layers of the ischemic zone, i.e., inner, middle, and outer thirds. Ischemic cellular damage was classified and quantified from grade 0 to grade 5 (0 being normal and 5 being the most severe damage) with light microscopy and confirmed by electron microscopy. Layers of 200 micrometers immediately beneath the endocardium and epicardium showed minimal ischemic damage of less than grade 1.4 regardless of duration of ischemia in all hearts. In the ischemic left ventricular wall, except for the above layers, a definite transmural gradient of the cellular damage existed from the inner third (grade 2.3 +/- 0.1) to the outer third (grade 1.3 +/- 0.2) at 20 minutes of ischemia and at 40 minutes of ischemia (grades 3.6 +/- 0.1 and 1.9 +/- 0.3, respectively). The transmural ischemic damage gradient disappeared at 120 minutes of ischemia, where the inner and outer third ischemic grades were both 5.0 +/- 0.1. The data suggest that the limited ischemic damage which occurs in the few cell layers beneath endocardium and epicardium may be explained by regional collateral blood flow. An early ischemic damage wavefront phenomenon does exist in the pig myocardium and is independent of myocardial blood flow and its distribution. The transmural cell damage gradient may be the result of transmural gradients of wall stress and intramyocardial pressure in vivo. Therefore, it appears that factors other than blood flow are the major determinants of ischemic cellular damage in the left ventricular wall of hearts lacking a collateral blood supply.

Virulence Characterization of International Collections of the Wheat Stripe Rust Pathogen, Puccinia striiformis f. sp. tritici

Wheat stripe rust (yellow rust [Yr]), caused by Puccinia striiformis f. sp. tritici, is an economically important disease of wheat worldwide. Virulence information on P. striiformis f. sp. tritici populations is important to implement effective disease control with resistant cultivars. In total, 235 P. striiformis f. sp. tritici isolates from Algeria, Australia, Canada, Chile, China, Hungary, Kenya, Nepal, Pakistan, Russia, Spain, Turkey, and Uzbekistan were tested on 20 single Yr-gene lines and the 20 wheat genotypes that are used to differentiate P. striiformis f. sp. tritici races in the United States. The 235 isolates were identified as 129 virulence patterns on the single-gene lines and 169 virulence patterns on the U.S. differentials. Virulences to YrA, Yr2, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, YrUkn, Yr28, Yr31, YrExp2, Lemhi (Yr21), Paha (YrPa1, YrPa2, YrPa3), Druchamp (Yr3a, YrD, YrDru), Produra (YrPr1, YrPr2), Stephens (Yr3a, YrS, YrSte), Lee (Yr7, Yr22, Yr23), Fielder (Yr6, Yr20), Tyee (YrTye), Tres (YrTr1, YrTr2), Express (YrExp1, YrExp2), Clement (Yr9, YrCle), and Compair (Yr8, Yr19) were detected in all countries. At least 80% of the isolates were virulent on YrA, Yr2, Yr6, Yr7, Yr8, Yr17, YrUkn, Yr31, YrExp2, Yr21, Stephens (Yr3a, YrS, YrSte), Lee (Yr7, Yr22, Yr23), and Fielder (Yr6, Yr20). Virulences to Yr1, Yr9, Yr25, Yr27, Yr28, Heines VII (Yr2, YrHVII), Paha (YrPa1, YrPa2, YrPa3), Druchamp (Yr3a, YrD, YrDru), Produra (YrPr1, YrPr2), Yamhill (Yr2, Yr4a, YrYam), Tyee (YrTye), Tres (YrTr1, YrTr2), Hyak (Yr17, YrTye), Express (YrExp1, YrExp2), Clement (Yr9, YrCle), and Compair (Yr8, Yr19) were moderately frequent (>20 to <80%). Virulence to Yr10, Yr24, Yr32, YrSP, and Moro (Yr10, YrMor) was low (≤20%). Virulence to Moro was absent in Algeria, Australia, Canada, Kenya, Russia, Spain, Turkey, and China, but 5% of the Chinese isolates were virulent to Yr10. None of the isolates from Algeria, Canada, China, Kenya, Russia, and Spain was virulent to Yr24; none of the isolates from Algeria, Australia, Canada, Nepal, Russia, and Spain was virulent to Yr32; none of the isolates from Australia, Canada, Chile, Hungary, Kenya, Kenya, Nepal, Pakistan, Russia, and Spain was virulent to YrSP; and none of the isolates from any country was virulent to Yr5 and Yr15. Although the frequencies of virulence factors were different, most of the P. striiformis f. sp. tritici isolates from these countries shared common virulence factors. The virulences and their frequencies and distributions should be useful in breeding stripe-rust-resistant wheat cultivars and understanding the pathogen migration and evolution.

Mitochondrial K(ATP) channel activation reduces anoxic injury by restoring mitochondrial membrane potential

Mitochondrial membrane potential (DeltaPsi(m)) is severely compromised in the myocardium after ischemia-reperfusion and triggers apoptotic events leading to cell demise. This study tests the hypothesis that mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel activation prevents the collapse of DeltaPsi(m) in myocytes during anoxia-reoxygenation (A-R) and is responsible for cell protection via inhibition of apoptosis. After 3-h anoxia and 2-h reoxygenation, the cultured myocytes underwent extensive damage, as evidenced by decreased cell viability, compromised membrane permeability, increased apoptosis, and decreased ATP concentration. Mitochondria in A-R myocytes were swollen and fuzzy as shown after staining with Mito Tracker Orange CMTMRos and in an electron microscope and exhibited a collapsed DeltaPsi(m), as monitored by 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1). Cytochrome c was released from mitochondria into the cytosol as demonstrated by cytochrome c immunostaining. Activation of mitoK(ATP) channel with diazoxide (100 micromol/l) resulted in a significant protection against mitochondrial damage, ATP depletion, cytochrome c loss, and stabilized DeltaPsi(m). This protection was blocked by 5-hydroxydecanoate (500 micromol/l), a mitoK(ATP) channel-selective inhibitor, but not by HMR-1098 (30 micromol/l), a putative sarcolemmal K(ATP) channel-selective inhibitor. Dissipation of DeltaPsi(m) also leads to opening of mitochondrial permeability transition pore, which was prevented by cyclosporin A. The data support the hypothesis that A-R disrupts DeltaPsi(m) and induces apoptosis, which are prevented by the activation of the mitoK(ATP) channel. This further emphasizes the therapeutic significance of mitoK(ATP) channel agonists in the prevention of ischemia-reperfusion cell injury.

Calcium preconditioning inhibits mitochondrial permeability transition and apoptosis

We tested the hypothesis whether calcium preconditioning (CPC) reduces reoxygenation injury by inhibiting mitochondrial permeability transition (MPT). Cultured myocytes were preconditioned by a brief exposure to 1.5 mM calcium (CPC) and subjected to 3 h of anoxia followed by 2 h of reoxygenation (A-R). Myocytes were also treated with 0.2 microM/l cyclosporin A (CsA), an inhibitor of MPT, before A-R. A significant increase of viable cells and reduced lactate dehydrogenase release was observed both in CPC- and CsA-treated myocytes compared with the A-R group. Cytochrome c release was predominantly observed in the cytoplasm of myocytes in the A-R group in contrast with CPC- or CsA-treated groups, where it was restricted only to mitochondria. Similarly, the cell death by apoptosis was also markedly attenuated in these groups. Electron-dense Ca(2+) deposits in mitochondria were also less frequent. Atractyloside (20 microM/l), an adenine nucleotide translocase inhibitor, caused changes similar to those in the A-R group, suggesting a role of MPT in A-R injury. Protection by inhibition of MPT by CsA and CPC suggests that MPT plays an important role in reoxygenation/reperfusion injury. The data further suggest that preconditioning inhibits MPT by inhibiting Ca(2+) accumulation by mitochondria.

Direct detection of endogenous hydroxyl radical production in cultured adult cardiomyocytes during anoxia and reoxygenation. Is the hydroxyl radical really the most damaging radical species?

Isolated adult rat cardiac myocytes were subjected to anoxia and substrate deprivation for 15, 30, 60, 90, and 120 minutes and reoxygenation for 120 seconds. The supernatant and cell extract were analyzed for hydroxyl radicals (.OH) with high-performance liquid chromatography using salicylate as a trapping agent. The production of intracellular H2O2 as a possible precursor of .OH was also documented using the fluorescent probe dichlorofluorescein diacetate. The release of the cytosolic enzyme lactate dehydrogenase (LDH) and malondialdehyde (MDA) formation were used as cell injury markers. Trypan blue and horseradish peroxidase stains were used as markers for altered membrane permeability. Maximum formation of .OH was observed in myocytes subjected to 15 minutes of anoxia/reoxygenation (2.83 +/- 0.27 nmol/mg protein), at which time no injury was observed at light and ultramicroscopic levels. On the other hand, there was no correlation between the amount of .OH production and different parameters of cell injury in myocytes subjected to anoxia/reoxygenation longer than 15 minutes. Myocytes developed extensive blebbing, loss of cell membrane permeability, and ultrastructural damage. The enzyme leakage was minimal at 15 minutes (0.094 +/- 0.021 units/mg protein) and increased fivefold after 120 minutes (0.428 +/- 0.069 units/mg protein). Similarly, MDA increased from 0.78 +/- 0.14 nmol/mg protein at 15 minutes to 1.65 +/- 0.35 nmol/mg protein at 120 minutes. Incubation with 1 mM deferoxamine reduced the .OH production at all anoxic intervals, most significantly at 15 minutes, but did not decrease LDH and MDA release or provide ultrastructural preservation. However, preincubation with 2.5 microM diphenylphenylenediamine markedly reduced both LDH and MDA release and offered prominent ultrastructural protection. These results suggest that 1) myocytes were able to generate .OH endogenously; 2) maximum .OH was produced at 15 minutes after anoxic reoxygenation without compromising cell viability; 3) prolongation of the anoxic period exacerbated cell damage without parallel increase in .OH generation; 4) there was no significant production of .OH after 15 minutes of anoxia/reoxygenation with or without treatment of deferoxamine, suggesting that prolonged anoxia/reoxygenation does not induce additional .OH formation and thus mediate cell injury; and 5) it is likely that the damage to myocytes in this system was still mediated by free radicals other than .OH, as indicated by the protection by diphenylphenylenediamine against the cellular injury.

Calcium preconditioning elicits strong protection against ischemic injury via protein kinase C signaling pathway

We tested the hypothesis that elevation of [Ca2+]i during Ca2+ preconditioning (CPC) is a strong activator of protein kinase C (PKC) and confers unique protection against ischemic injury. CPC consisted of three cycles of Ca2+ depletion (1 minute each) and Ca2+ repletion (5 minutes each). Langendorff-perfused rat hearts were subjected to 40 minutes of global ischemia followed by 30 minutes of reperfusion. Significant functional recovery and decreased lactate dehydrogenase release were observed in CPC hearts compared with ischemic control hearts. In addition, ATP contents were significantly higher and cell structure was better preserved in CPC hearts than in ischemic control hearts. Administration of chelerythrine, a specific PKC inhibitor, completely abolished the CPC-induced cardioprotection. In other groups, in which Ca2+ influx during CPC was inhibited with verapamil, amiloride, and low Na+ perfusion, cardioprotection was significantly reduced. The prominent increase in the membrane PKC activity after CPC was in agreement with immunolocalization of PKC-alpha and PKC-delta in the cell membrane of CPC hearts. These results demonstrate that (1) a transient increase in [Ca2+]i is a prominent feature of CPC and is a strong stimulus for the activation of PKC, (2) the elevation of [Ca2+]i likely occurs via an L-type Ca2+ channel and Na(+)-Ca2+ exchanger, and (3) PKC plays a crucial role in the subcellular mechanisms of protection by CPC.

Holmium: YAG lasertripsy for ureteric calculi: an experience of 300 procedures

OBJECTIVE

To assess the success of holmium:YAG lasertripsy in the management of ureteric calculi and to audit the complications of the procedure, with special reference to strictures in the ureter.

PATIENTS AND METHODS

A total of 300 ureteroscopic laser procedures were carried out on 265 patients (204 male and 61 female, median age 51 years, range 2-95) with ureteric calculi. At ureteroscopy, the calculi were present in the upper ureter in 44%, mid-ureter in 37% and lower ureter in 19% of patients; most calculi were > 5 mm. A 7.5 F Wolf semi-rigid ureteroscope was used and the holmium:YAG laser energy delivered using the Sharplan ML210 device at 0.8-1.0 J/pulse. The patients were followed up at approximately 6 weeks with limited intravenous urography or ultrasonography to assess clearance and the incidence of strictures.

RESULTS

Stones were completely cleared in 90% of the patients, with the best results in the lower and mid-ureter (97% and 96%, respectively) followed by the upper ureter (89%). Alternative procedures were required in only 17 (7%) patients; extracorporeal shock-wave lithotripsy in 13, percutaneous nephrolithotomy in two and open pyelolithotomy in two patients. Complications with ureteric perforation in 11 patients, including laparotomy for peritonitis in one, serious sepsis in two and strictures in 10 patients. Strictures were more common in association with impacted calculi in the upper ureter early in the series.

CONCLUSIONS

Holmium:YAG lasertripsy is a highly effective treatment for ureteric calculi, with strictures related to the treatment of difficult upper ureteric calculi.

Needle knife papillotomy: how safe and how effective?

Between January 1986 and July 1988 needle knife papillotomy was attempted in 103 patients after failure of conventional access for endoscopic sphincterotomy (96 cases) or diagnostic cholangiography (seven cases). Access was obtained at the same session in 36 cases and at a subsequent attempt within 2 to 5 days in a further 43, an overall success rate of 77%. The procedure related morbidity and mortality in the therapeutic group were 5.2% and 2.0% respectively. There were no deaths or complications in the diagnostic group. Needle knife papillotomy is a valuable adjunct to conventional techniques of biliary access.

Detection of hydroxyl radicals in the post-ischemic reperfused heart using salicylate as a trapping agent

The formation of hydroxyl radical in the post-ischemic reperfused heart was measured with high performance liquid chromatography and ultraviolet detection using salicylic acid. Hydroxyl radicals react with salicylic acid yielding 2,3- and 2,5-dihydroxybenzoic acid, which can be separated by the liquid chromatography. Isolated rat hearts were perfused with 1 mM salicylic acid and were subjected to 30 mins of global ischemia followed by aerobic or anaerobic reperfusion at 37 degrees C. The effluent from the hearts was collected at various intervals, extracted with ether, and injected into the high performance liquid chromatography unit. 2,5-dihydroxybenzoic acid was present only after aerobic reperfusion and was not detected before ischemia. The liquid chromatography peak of 2,3-dihydroxybenzoic acid was too small for quantitation. The concentration of 2,5-dihydroxybenzoic acid was the highest within 300 s of reperfusion. 2,5-dihydroxybenzoic acid was not detected in the ischemic hearts during anaerobic reperfusion. In ischemic hearts perfused with mannitol, the amount of 2,5-dihydroxybenzoic acid after reperfusion was reduced. These data suggest that hydroxyl radicals are produced in the post-ischemic reperfused heart and that the present method is useful and reliable for the measurement of hydroxyl radicals in the heart.

An ethnomedicinal survey and documentation of important medicinal folklore food phytonims of flora of Samahni valley, (Azad Kashmir) Pakistan

Ethnobotanical knowledge is one of the precious cultural heritage parts of an area that involves the interaction between plants and people and foremost among these are the management of plant diversity by indigenous communities and the traditional use of medicinal plants. An ethnobotanical analysis was conducted in order to document the traditional medicinal uses of plants, particularly medicinally important folklore food phytonims of flora of Samahni valley, Azad Kashmir (Pakistan). In the valley, inhabitants use different taxa of flora in two different ways; herbal medicines and food (vegetable and fruits) medicines. The distinctive geographic position and historic demological background of the area keep folk phytotherapy potential of medicinal herbs hitherto alive, which are used in various forms; as regular herbal medicines prescribed by Hakeems (herbal practitioners) and as food (medicines) recepies suggested by elder people. Among these, some herbs are used as single remedy while others depict better curative effects in synergistic mode against various ailments. Some interesting and uncommon findings are as; Sisymbrium irio is used for treatment of measles, asthma; Solanum miniatum to cure urinary calculi, heart pain, rheumatism, Momordica balsamina leaves as wound healer; Allium sativum bulb juice as anti cancer, contraceptive, blood pressure; Boerhavia diffusa roots as anti jaundice, anemia, edema; Capsicum annuum fruit as omen against evil eye and giant, yellow fever; Corriandrum sativum seeds as diuretic, anti spermatogenesis; Raphanus sativus seeds against syphilis; Solanum miniatum fruit for treatment of enlarged spleen and liver; seed's oil of Pisum sativum as anti spermatogenesis; Bauhinia variegata for skin diseases, ulcers; Malva sylvestris for cough, bladder ulcer; Phoenix sylvestris kernel as anti-aging tonic; Phyllanthus emblica for diuretic, anemia, biliousness; Terminalia chebula to cure chronic ulcers, carious teeth pain, heart problems; Veronica anthelmintica for bandage of broken bones and Withania coagulans is used to treat small pox. Many wild plants are eaten green and raw as salad, or in boiled form of soup as blood and intestine cleansing tonics. Moreover, some plants are spiritually recorded as sacred and used as ritual plant for good omens or against the evil eye and removal of giant. About 95 species of 38 families were recorded to be important part of phyto heritage of folk pharmacopoeia of Samahni valley. Among most frequent used families are Papilionaceae 9.47%, Solanaceae and Poaceae 8.42% each, Cucurbitaceae 7.36% and Brassicaceae and Rosaceae 6.31% each. Among the surveyed families used to treat various diseases, Solanaceae is at first rank with 9.74%, Brassicaceae 8.23% and Cucurbitaceae 7.39% subsequently. Most commonly used families with highest percentage of plants used as food medicines are Solanaceae (11.37%), Brassicaceae (8.38%) and Papilionaceae (7.18%) respectively. Most frequent plant parts used are; roots, leaves, seeds and flowers while popular forms of plants uses are decoction, poultice, infusions, soups and raw form as salad. Importance of ethnobotanical inventory constructed from ethnomedicinal uses and folklore phytonims of flora in perspectives of initiative for future phytochemical and pharmacological research on these taxa to develop and discover of new drugs is present and discussed.

Myocardial dysfunction and ultrastructural alterations mediated by oxygen metabolites

The direct effect of oxygen metabolites was studied on isolated perfused rat hearts. Superoxide anion (O2-.) and hydrogen peroxide (H2O2) were generated by adding purine (2.3 mM) and purified xanthine oxidase (0.06 U/ml) to Krebs-Henseleit buffer (pH 7.4). Xanthine oxidase was added to the purine-containing perfusate either near the aorta (group A, which gave H2O2 less than 10 microM) or at a distant point from the aorta (group B, which gave 250 to 300 microM H2O2). The generation rate of O2-. was 31.7 +/- 1.0 nmol/ml/min in the experimental conditions. Contractile function, tissue adenosine triphosphate (ATP), and ultrastructure were not affected in group A. In contrast, hearts in group B showed marked decrease in contractility (+dP/dt) to 24.4 +/- 4.3% of control values. ATP levels were also markedly reduced from control values of 23.4 +/- 0.7 to 7.4 +/- 0.7 mumol/g dry tissue. Ultrastructure in group B hearts revealed "wavy" and disintegrated sarcolemma, depletion of glycogen deposits, and swelling and disruption of mitochondria. Release of the thiobarbituric acid reactive products including malondialdehyde was significant in the effluent (1.68 +/- 0.17 nmol/min/g wet tissue). These changes were almost completely prevented by catalase, but not by superoxide dismutase and deferoxamine. Moreover, exogenous H2O2 perfusion (300 microM) showed results similar to group B hearts. These observations suggest that H2O2 plays a major role in the injury. O2- does not appear to damage hearts directly, although it is important as a precursor of H2O2 and other radical species including hydroxyl radical.

Pathologic assessment of myocardial cell necrosis and apoptosis after ischemia and reperfusion with molecular and morphological markers

The present work illustrates the critical subcellular changes in the rat heart after 10-30 min of left coronary artery (LCA) occlusion and 120 min of reperfusion with a combination of several staining techniques. Triphenyltetrazolium chloride (TTC) to detect non-injured myocytes, horseradish peroxidase (HRP) and terminal deoxynucleotide nick-end labeling (TUNEL) to detect necrotic and apoptotic cells were employed and electron microscopy (EM) was used to validate these changes. After 20 min of LCA occlusion, myocytes began to undergo necrosis whilst after 10 min occlusion, no myocyte underwent irreversible cell injury in the risk area. After 30 min of LCA occlusion and 120 min reperfusion, 36.3, 26.6 and 25% cells were normal, necrotic, and reversibly injured, respectively; the remaining 12.8% cells were apoptotic. Necrotic cells were strongly positive with HRP and negative for TTC and TUNEL. TUNEL-positive or apoptotic cells were slightly HRP-positive, indicating altered cell membrane permeability. Reversibly-injured myocytes were TTC-, HRP- and TUNEL-negative. These changes were more accurately defined in the 100- microm thick sections than in the traditional slices. It is concluded that: (1) TTC-staining of 100- microm thick sections is far superior and accurate for the detection of ischemic changes with shorter period of ischemia (10 min); (2) the combination of TTC-staining, HRP reaction and TUNEL method is excellent for demarcation of early ischemic changes; (3) TTC-negativity in ischemia less than 20 min does not indicate necrosis but only represents reversible changes; (4) the apoptosis is absent in early ischemia of 20 min with or without reperfusion at a time when sufficient ATP is present, and appears only after 30 min of coronary ligation and reperfusion; and (5) the apoptotic cells lose membrane integrity accompanied by decreased glycocalyx thickness and cell swelling as opposed to commonly known characteristics of apoptotic cells.