Protective effects of rutin and naringin in testicular ischemia-reperfusion induced oxidative stress in rats

INTRODUCTION

Testicular torsion and detorsion causes reperfusion injury which damages the testicular tissue and affects the quality of sperm. Deterioration in the quality of sperm worldwide is the recent scenario and one of its reasons is testicular ischemic/ reperfusion (IR) injury. Therefore the present study aims at producing new drugs for the treatment of testicular IR injury.

METHODS

42 animals were selected for the study and divided into 7 groups, each containing 6 rats. Bioflavonoids were tested for their efficacy in reversing the damage done to the testicular tissue by causing testicular torsion and detorsion in rats. As oxidative stress produced in the above condition causes tissue damage, MDA level was measured and antioxidant enzymes SOD and catalse were evaluated. Histological examination was conducted to find the extent of damage and the protective effect of rutin and naringin. One-way ANOVA and Tukey's post-hoc test were used for data analysis. A p-value<0.001 was considered statistically significant.

RESULTS

MDA levels increased and antioxidant enzymes decreased drastically in the group of rats with testicular torsion and detorsion which clearly indicates a rise in oxidative stress (68% rise in the case of MDA and 20% and 16% decrease in SOD and catalase concentrations, respectively). Rutin and naringin-treated groups showed the beneficial effects of the medicinal drugs, particularly in higher doses. Rutin, 10 mg/kg, was effective when compared to naringin in providing protection. Compared to the animals in the control group, there was a 30% reduction in MDA levels and a 20% increment in SOD levels plus a five-fold increase in catalse in the rutin-treated group (10 mg/kg). Histological examination supported the above claims.

CONCLUSION

Oxidative stress in testicular injury affects the quality of sperm. Rutin and naringin in higher doses protected testicular tissue effectively. Further studies in this direction may prove beneficial.

Direct protection of cultured neurons from ischemia-like injury by minocycline

Minocycline, a tetracycline antibiotic, is now known to protect cells via an anti-inflammatory mechanism. We further explored this effect using an in vitro model of ischemia-like injury to neurons. Coculturing neurons with microglia, the brain's resident immune cell, modestly increased cell death due to oxygen and glucose deprivation (OGD), compared to neurons alone. Treatment of cocultures with minocycline decreased cell death to a level significantly lower than that of neurons alone. Treatment of cocultures with minocycline or inhibitors of various immune mediators, also led to decreased cell death. Importantly, treatment of neuron cultures without added microglia with these same inhibitors of tissue plasminogen activator, matrix metalloproteinases, TNF-alpha and inducible nitric oxide synthase as well as minocycline also led to decreased cell death. Thus, anti-inflammatory treatments appear to be directly protective of neurons from in vitro ischemia.

Hepatoprotective actions of melatonin: Possible mediation by melatonin receptors

Melatonin, the hormone of darkness and messenger of the photoperiod, is also well known to exhibit strong direct and indirect antioxidant properties. Melatonin has previously been demonstrated to be a powerful organ protective substance in numerous models of injury; these beneficial effects have been attributed to the hormone’s intense radical scavenging capacity. The present report reviews the hepatoprotective potential of the pineal hormone in various models of oxidative stress in vivo, and summarizes the extensive literature showing that melatonin may be a suitable experimental substance to reduce liver damage after sepsis, hemorrhagic shock, ischemia/reperfusion, and in numerous models of toxic liver injury. Melatonin’s influence on hepatic antioxidant enzymes and other potentially relevant pathways, such as nitric oxide signaling, hepatic cytokine and heat shock protein expression, are evaluated. Based on recent literature demonstrating the functional relevance of melatonin receptor activation for hepatic organ protection, this article finally suggests that melatonin receptors could mediate the hepatoprotective actions of melatonin therapy.

Giant coronary sinus and a review of the literature

We report a case of persistent left superior caval vein whom presented with angina pectoris and exertional dyspnea. Echocardiography showed wall motion disturbances with an ejection fraction of 40% and a very large coronary sinus. Our case is a very rare case with a very large coronary sinus presented with angina pectoris.

Ischemic colitis

Ischemic colitis is the most common form of ischemic enteropathy and occurs more frequently in elderly people. Although the etiology of ischemic colitis is diverse, the most common cause is acute, self-limited disruption of blood supply to the intestine. The typical clinical symptoms of ischemic colitis are minor abdominal pain and mild muscular tension of the affected colon segment. Hematochezia is very common, however, massive hemorrhage that can affect hemodynamics is not frequent. If the lesion is located in the mucous layer or submucosal layer, the disease is often transient and self-limited. Acute ischemic colitis with transmural infarction may lead to colonic necrosis and even death. Colonoscopy and biopsy are the gold standard for diagnosis of the disease. Most patients with ischemic colitis improve after conservative treatment in one or two days. Approximately 20% of patients may deteriorate to develop peritonitis and need surgical treatment.

Determinants of delayed preconditioning against myocardial stunning in chronically-instrumented pigs

To test the hypothesis that a critical stenosis prevents delayed preconditioning against stunning, studies were conducted in pigs chronically-instrumented with occluders and segment-shortening crystals. In the setting of a critical stenosis, a preconditioning stimulus of repetitive brief occlusions resulted in infarction. Thereafter, a single 10-minute occlusion was used as the preconditioning stimulus. Delayed preconditioning against stunning was documented on subsequent days by the deficit-of-function following brief repetitive occlusions. In contrast to experiments in the naïve heart, the deficit-of-function improved on the day after a single 10-minute occlusion (from 60+/-14 to 24+/-6 arbitrary units, p=0.003), and similar improvement occurred when reperfusion was performed through a critical stenosis (32+/-6 units, p=0.02 vs. naïve and p=0.34 vs. no stenosis). Delayed preconditioning also reduced the frequency of ventricular fibrillation, and produced a 4-fold increase in both calcium-dependent and calcium-independent NOS activity. Thus, a critical stenosis did not prevent delayed preconditioning against stunning.

Warfare Vascular Injuries

Vascular injuries as a part of combat injuries have been recorded since times immemorial. Responsible for death due to exsanguination, the management of vascular injuries was ligation or amputation till the landmark Vietnam experience. The present day management has evolved with advances in modern technology and may start at the battlefield with the application of a tourniquet with the definitive treatment continuing beyond the combat operation theatres. A basic understanding of both blunt and penetrating vascular injuries will help minimize mortality and morbidity.

Myocardial perfusion imaging and infarct characterization using multidetector cardiac computed tomography

Until recently, computed tomography coronary angiography was restricted to the anatomical assessment of coronary stenosis, whereas the functional significance of coronary lesions remained outside of its scope. Nevertheless, the kinetics of iodinated contrast is similar to gadolinium-diethylenetriamine pentaacetic acid used in contrast-enhanced magnetic resonance imaging, allowing assessment of myocardial perfusion and viability by cardiac computed tomography.

Cell membrane modification for rapid display of bi-functional peptides: a novel approach to reduce complement activation

Ischemia and reperfusion of organs is an unavoidable consequence of transplantation. Inflammatory events associated with reperfusion injury are in part attributed to excessive complement activation. Systemic administration of complement inhibitors reduces reperfusion injury but leaves patients vulnerable to infection. Here, we report a novel therapeutic strategy that decorates cells with an anti-complement peptide. An analog of the C3 convertase inhibitor Compstatin (C) was synthesized with a hexahistidine (His(6)) tag to create C-His(6). To decorate cell membranes with C-His(6), fusogenic lipid vesicles (FLVs) were used to incorporate lipids with nickel (Ni(2+)) tethers into cell membranes, and these could then couple with C-His(6). Ni(2+) tether levels to display C-His(6) were modulated by changing FLV formulation, FLV incubation time and FLV levels. SKOV-3 cells decorated with C-His(6) effectively reduced complement deposition in a classical complement activation assay. We conclude that our therapeutic approach appears promising for local ex vivo treatment of transplanted organs to reduce complement-mediated reperfusion injury.

Black esophagus: Acute esophageal necrosis syndrome

Acute esophageal necrosis (AEN), commonly referred to as “black esophagus”, is a rare clinical entity arising from a combination of ischemic insult seen in hemodynamic compromise and low-flow states, corrosive injury from gastric contents in the setting of esophago-gastroparesis and gastric outlet obstruction, and decreased function of mucosal barrier systems and reparative mechanisms present in malnourished and debilitated physical states. AEN may arise in the setting of multiorgan dysfunction, hypoperfusion, vasculopathy, sepsis, diabetic ketoacidosis, alcohol intoxication, gastric volvulus, traumatic transection of the thoracic aorta, thromboembolic phenomena, and malignancy. Clinical presentation is remarkable for upper gastrointestinal bleeding. Notable symptoms may include epigastric/abdominal pain, vomiting, dysphagia, fever, nausea, and syncope. Associated laboratory findings may reflect anemia and leukocytosis. The hallmark of this syndrome is the development of diffuse circumferential black mucosal discoloration in the distal esophagus that may extend proximally to involve variable length of the organ. Classic “black esophagus” abruptly stops at the gastroesophageal junction. Biopsy is recommended but not required for the diagnosis. Histologically, necrotic debris, absence of viable squamous epithelium, and necrosis of esophageal mucosa, with possible involvement of submucosa and muscularis propria, are present. Classification of the disease spectrum is best described by a staging system. Treatment is directed at correcting coexisting clinical conditions, restoring hemodynamic stability, nil-per-os restriction, supportive red blood cell transfusion, and intravenous acid suppression with proton pump inhibitors. Complications include perforation with mediastinal infection/abscess, esophageal stricture and stenosis, superinfection, and death. A high mortality of 32% seen in the setting of AEN syndrome is usually related to the underlying medical co-morbidities and diseases.

Current state of hypothermic machine perfusion preservation of organs: The clinical perspective

This review focuses on the application of hypothermic perfusion technology as a topic of current interest with the potential to have a salutary impact on the mounting clinical challenges to improve the quantity and quality of donor organs and the outcome of transplantation. The ex vivo perfusion of donor organs on a machine prior to transplant, as opposed to static cold storage on ice, is not a new idea but is being re-visited because of the prospects of making available more and better organs for transplantation. The rationale for pursuing perfusion technology will be discussed in relation to emerging data on clinical outcomes and economic benefits for kidney transplantation. Reference will also be made to on-going research using other organs with special emphasis on the pancreas for both segmental pancreas and isolated islet transplantation. Anticipated and emerging benefits of hypothermic machine perfusion of organs are: (i) maintaining the patency of the vascular bed, (ii) providing nutrients and low demand oxygen to support reduced energy demands, (iii) removal of metabolic by-products and toxins, (iv) provision of access for administration of cytoprotective agents and/or immunomodulatory drugs, (v) increase of available assays for organ viability assessment and tissue matching, (vi) facilitation of a change from emergency to elective scheduled surgery with reduced costs and improved outcomes, (vii) improved clinical outcomes as demonstrated by reduced PNF and DGF parameters, (viii) improved stabilization or rescue of ECD kidneys or organs from NHBD that increase the size of the donor pool, (ix) significant economic benefit for the transplant centers and reduced health care costs, and (x) provision of a technology for ex vivo use of non-transplanted human organs for pharmaceutical development research.

Infectious Diseases of the Lower Gastrointestinal Tract

Gastrointestinal (GI) infections are a major cause of morbidity and mortality worldwide. Although infectious organisms are often recovered by microbiological methods, surgical pathologists play an invaluable role in diagnosis. The lower GI tract, including the appendix, large bowel, and anus, harbors a wide variety of pathogens. Some infections are part of disseminated disease, whereas others produce clinicopathologic scenarios that are specific to the lower GI tract. This review focuses on selected infectious disorders of the lower GI tract that may be encountered by the general surgical pathologist, including viral, bacterial, fungal, and parasitic organisms, and including infections caused by food- and water-borne pathogens. Diagnostic gross and histologic features are discussed, as well as useful clinical features and ancillary diagnostic techniques. Pertinent differential diagnoses are also emphasized, including other inflammatory conditions of the gut (such as ischemia or idiopathic inflammatory bowel disease) that can be mimicked by lower GI infections.

Hypoxia-inducible factor and vascular endothelial growth factor in the neuroretina and retinal blood vessels after retinal ischemia

Retinal ischemia arises from circulatory failure. As the retinal blood vessels are key organs in circulatory failure, our aim was to study the retinal vasculature separately from the neuroretina to elucidate the role of hypoxia-inducible factor (HIF) 1α and 1β and vascular endothelial growth factor (VEGF) in retinal ischemia. Retinal ischemia was induced in porcine eyes by applying an intraocular pressure, followed by 12 h of reperfusion. HIF-1α mRNA expression was not affected by ischemia, while immunofluorescence staining was higher after ischemia in the neuroretina. HIF-1β immunoreactivity and mRNA expression were unaffected. VEGF protein levels in the vitreous humor and VEGF staining in the neuroretina were more pronounced in eyes subjected to ischemia than in the sham eyes. VEGF may be activated downstream of HIF-1 and is known to stimulate retinal neovascularization, which causes sight-threatening complications. These results emphasize the need for pharmacological treatment to block the HIF and VEGF signaling pathways in retinal ischemia.

Bioelectrical impedance may predict cell viability during ischemia and reperfusion in rat liver

Ischemia and reperfusion (I/R) injury is a major cause of hepatic failure after liver surgery, but no method could monitor or predict it real-time during surgery. We measured bioelectrical impedance (BEI) and cell viability to assess the usefulness of BEI during I/R in rat liver. A 70% partial liver ischemia model was used. BEI was measured at various frequencies. Adenosine triphosphate (ATP) content, and palmitic acid oxidation rate were measured, and histological changes were observed in order to quantify liver cell viability. BEI changed significantly during ischemia at low frequency. In the ischemia group, BEI increased gradually during 60 min of ischemia and had a tendency to plateau thereafter. The ATP content decreased below 20% of the baseline level. In the I/R group, BEI recovered to near baseline level. After 24 hr of reperfusion, the ATP contents decreased to below 50% in 30, 60 and 120 min of ischemia and the palmitic acid metabolic rates decreased to 91%, 78%, and 74%, respectively, compared with normal liver. BEI may be a good tool for monitoring I/R during liver surgery. The liver is relatively tolerant to ischemia, however after reperfusion, liver cells may be damaged depending upon the duration of ischemia.

Beneficial effects of N-acetyl cysteine on pancreas and kidney following experimental pancreatic ischemia-reperfusion in rats

OBJECTIVE

To evaluate the protective effects of N-acetyl cysteine on the pancreas and kidney after pancreatic ischemia reperfusion injury in a rat model.

METHODS AND MATERIALS

Pancreatic ischemia reperfusion was performed in Wistar rats for 1 hour. Revascularization was achieved followed by 4 h of reperfusion. A total of 24 animals were divided into four groups: Group 1: sham; Group 2: pancreatic ischemia reperfusion without treatment; Group 3: pancreatic ischemia reperfusion plus N-acetyl cysteine intravenously; and Group 4: pancreatic ischemia reperfusion plus N-acetyl cysteine per os. Blood and tissue samples were collected after reperfusion.

RESULTS

There were significant differences in amylase levels between Group 1 (6.11+/-0.55) and Group 2 (10.30+/-0.50) [p=0.0002] as well as between Group 2 (10.30+/-0.50) and Group 4 (7.82+/-0.38) [p=0.003]; creatinine levels between Group 1 (0.52 +/- 0.07) and Group 2 (0.77+/-0.18) [p=0.035] as well as between Group 2 (0.77+/-0.18) and Group 3 (0.48+/-0.13) [p=0.012]; and pancreatic tissue thiobarbituric acid reactive substance levels between Group 1 (1.27+/-0.96) and Group 2 (2.60+/-3.01) [p=0.026] as well as between Group 2 (2.60+/-3.01) and Group 4 (0.52+/-0.56) [p=0.002]. A decrease in pancreatic tissue GST-alpha3 gene expression was observed in Group 2 in comparison to Group 1 (p =0.006), and an increase was observed in Groups 3 and 4 when compared to Group 2 (p= 0.025 and p=0.010, respectively).

CONCLUSION

This study provides evidence that N-acetyl cysteine has a beneficial effect on pancreatic ischemia reperfusion injury and renal function in a rat model.

Effect of propofol on cardiac function and gene expression after ischemic-reperfusion in isolated rat heart

Background

The aim of this study was to examine the cardiac function and transcriptional response of the heart to propofol after ischemia-reperfusion.

Methods

Rat hearts were Langendorff-perfused using the modified Krebs-Henseleit buffer, and took 20 min stabilizing periods, 40 min ischemia periods, and then 120 min reperfusion period. The hearts were divided into 5 groups; Control: 180 min perfusion after stabilization, Ischemic: 40 min global ischemia after stabilization, followed by 120 min reperfusion, Pre: 2 µM propofol treatment was preformed only before ischemia, Post: 2 µM propofol treatment was performed only during reperfusion after ischemia, Pre/Post: 2 µM propofol treatment was performed both before and after ischemia. The measurement for cardiac performances, such as left ventricular developed pressure (LVDP), rate of left ventricular pressure generation (dP/dt), heart rate, and coronary flow were obtained. The expression profiles of isolated mRNA were determined by using Agilent microarray and real time-polymerase chain reaction (RT-PCR) was used to confirm the microarray results for a subset of genes.

Results

The Post group showed better LVDP and dP/dt than the Ischemic group. But there were no significant differences in heart rate and coronary flow among the groups. On the results of RT-PCR, the expressions of Abcc9, Bard1, and Casp4 were increased, but the expressions of Lyz, Casp8, and Timp1 were decreased in the Post group compared with the Ischemic group.

Conclusions

This study suggests that 2 µM propofol may provide cardioprotective effect, and modulate gene expression such as apoptosis, and K_ATP ion channel related-genes during reperfusion in the isolated rat hearts.

Effect of vasopressin on survival of Purkinje neurons in rat cerebellar slices after an in vitro simulated ischemia

BACKGROUND

Arginine vasopressin (AVP) is frequently used in patients under the risk of brain injury. It has been shown to induce brain injury after ischemia and reperfusion in in vivo animal models. We determined the effect of vasopressin on the brain injury after ischemia-reperfusion using in vitro model.

METHODS

Cerebellar brain slices were prepared from adult Sprague-Dawley rats. They were then subjected to simulated ischemia (oxygen-glucose deprivation) for 20 min in the absence (control) or presence of vasopressin (5, 10, 50, 100, 500 pg/ml). After being recovered in oxygenated artificial cerebrospinal fluid for 5 h, they were fixed for morphologic examination to determine the percentage of live Purkinje cells.

RESULTS

There were no differences in the survival rate of Purkinje cells among the control and vasopressin groups.

CONCLUSIONS

Vasopressin at concentrations studied has no direct effect on brain ischemia-reperfusion injury.

The effect of Allium sativum on ischemic preconditioning and ischemia reperfusion induced cardiac injury

In the present study, the effect of garlic (Allium sativum) extract on ischemic preconditioning and ischemia-reperfusion induced cardiac injury has been studied. Hearts from adult albino rats of Wistar strain were isolated and immediately mounted on Langendorff's apparatus for retrograde perfusion. After 15 minutes of stabilization, the hearts were subjected to four episodes of 5 min ischemia, interspersed with 5 min reperfusion (to complete the protocol of ischemic preconditioning), 30 min global ischemia, followed by 120 min of reperfusion. In the control and treated groups, respective interventions were given instead of ischemic preconditioning. The magnitude of cardiac injury was quantified by measuring Lactate Dehydrogenase and creatine kinase concentration in the coronary effluent and myocardial infarct size by macroscopic volume method. Our study demonstrates that garlic extract exaggerates the cardio protection offered by ischemic preconditioning and per se treatment with garlic extract also protects the myocardium against ischemia reperfusion induced cardiac injury.

Bedsores: "top to bottom" and "bottom to top"

Bedsore is a global problem concerning the bedridden, infirm, debilitated and malnourished patients in hospitals and community setups. The cost of treatment is enormous involving billions of dollars to nations and individuals. Mortality increases two to six times if bedsores are present. There is little research done despite its commonness to understand how they occur or why they occur; etiology is not much understood. The two theories called 'top to bottom' and 'bottom to top' contradict each other. It is thought that 'pressure', shear-stress' and 'ischemia' may be causing it in some yet to be understood way.There is little awareness on how to prevent them or how to treat them if they do occur. Seldom applied, various scales exist and should be used to identify patients at high risk. Braden scale is the most tested and widely accepted scale. The various available dressings and pressure relief devices are mostly inadequately studied; which is superior is a question that begs an answer. This article aims to underline the importance of bedsores by reviewing our current and past knowledge with emphasis on practical implications thereof.

Dobutamine stress echocardiography and tissue synchronization imaging

Dobutamine stress echocardiography has emerged as a reliable method for the diagnosis of coronary artery disease and the management of its treatment. Several studies have shown that that this technique works with 80-85% accuracy in comparison with other imaging methods. There are few studies aimed at developing the clinical utility of dobutamine stress echocardiography for the evaluation of normal and abnormal segments that result from dobutamine stress with Tissue Synchronization Imaging.

Strangulation Resulting from an Encasement of the Small Intestinal Loop by the Omentum without an Adhesive Band

The most common cause of small-bowel obstructions in adults is postoperative adhesions. However, strangulation of the small intestine in a patient without history of laparotomy is a rare condition. We experienced an unusual case of a small-bowel obstruction secondary to omental encasement in a patient without previous history of abdominal surgery or acute inflammatory process in the abdomen.

Pretreatment of cromolyn sodium prior to reperfusion attenuates early reperfusion injury after the small intestine ischemia in rats

AIM: To investigate the effects of Cromolyn Sodium (CS) pretreated prior to reperfusion on the activity of intestinal mucosal mast cells (IMMC) and mucous membrane of the small intestine in ischemia-reperfusion (IR) injury of rats.

METHODS: Thirty-two Sprague-Dawley (SD) rats were randomly divided into four groups: sham group (group S), model group (group M), high and low dosage of CS groups, (treated with CS 50 mg/kg or 25 mg/kg, group C1 and C2). Intestinal IR damage was induced by clamping the superior mesenteric artery for 45 min followed by reperfusion for 60 min. CS was intravenouly administrated 15 min before reperfusion. Ultrastructure and counts of IMMC, intestinal structure, the expression of tryptase, levels of malondisldehyde (MDA), TNF-α, histamine and superoxide dismutase (SOD) activity of the small intestine were detected at the end of experiment.

RESULTS: The degranulation of IMMC was seen in group M and was attenuated by CS treatment. Chiu’s score of group M was higher than the other groups. CS could attenuate the up-regulation of the Chiu’s score, the levels of MDA, TNF-α, and expression of tryptase and the down-regulation of SOD activity and histamine concentration. The Chiu’s score and MDA content were negatively correlated, while SOD activity was positively correlated to the histamine concentration respectively in the IR groups.

CONCLUSION: Pretreated of CS prior to reperfusion protects the small intestine mucous from ischemia-reperfusion damage, the mechanism is inhibited IMMC from degranulation.

Protective effect of curcumin against liver warm ischemia/reperfusion injury in rat model is associated with regulation of heat shock protein and antioxidant enzymes

AIM: To investigate the hypothesis that the protective effects of curcumin in hepatic warm ischemia/reperfusion (I/R) injury are associated with increasing heat shock protein 70 (Hsp70) expression and antioxidant enzyme activity.

METHODS: Sixty Sprague-Dawley male rats were randomly divided into sham, I/R, C + I/R groups. The model of reduced-size liver warm ischemia and reperfusion was used. Curcumin (50 mg/kg) was administered by injection through a branch of superior mesenteric vein at 30 min before ischemia in C + I/R group. Five rats were used to investigate the survival during 1 wk after operation in each group. Blood samples and liver tissues were obtained in the remaining animals after 3, 12, and 24 h of reperfusion to assess serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), liver tissue NO₂^- + NO₃^-, malondialdehyde (MDA) content, superoxide dismutase (SOD), catalase (CAT), nitricoxide synthase (NOS) and myeloperoxidase (MPO) activity, Hsp70 expression and apoptosis ratio.

RESULTS: Compared with I/R group, curcumin pretreatment group showed less ischemia/reperfusion-induced injury. CAT and SOD activity and Hsp70 expression increased significantly. A higher rate of apoptosis was observed in I/R group than in C + I/R group, and a significant increase of MDA, NO₂^- + NO₃^- and MPO level in liver tissues and serum transaminase concentration was also observed in I/R group compared to C + I/R group. Curcumin also decreased the activity of inducible NO synthase (iNOS) in liver after reperfusion, but had no effect on the level of endothelial NO synthase (eNOS) after reperfusion in liver. The 7 d survival rate was significantly higher in C + I/R group than in I/R group.

CONCLUSION: Curcumin has protective effects against hepatic I/R injury. Its mechanism might be related to the overexpression of Hsp70 and antioxidant enzymes.

Pharmacological preconditioning with diazoxide slows energy metabolism during sustained ischemia

Ischemic preconditioning (PC) is associated with slower destruction of the adenine nucleotide pool ( summation operatorAd) and slower rate of anaerobic glycolysis during ischemic stress. These changes are concordant with the preconditioned state, supporting an essential role of lowered energy demand in the cardioprotective mechanism of PC. Although pharmacological PC induced by the activation of mitochondrial K(ATP) channels also limits infarct size, its effect on energy metabolism during sustained ischemia is unknown. Using metabolite levels found at baseline and after a 15 min test episode of regional ischemia, the effect of a cardioprotective dose of diazoxide on metabolic features associated with PC was tested in barbital-anesthetized, open-chest dogs. Diazoxide (3.5 mg/kg at an intravenous rate of 1 mL/min) infused before a test episode of ischemia had no effect on baseline metabolic indices. However, during ischemic stress, treated hearts exhibited less destruction of ATP, less degradation of the summation operatorAd into nucleosides and bases, as well as less lactate production than control hearts subjected only to ischemic stress. Thus, diazoxide mimics the metabolic alterations observed in PC tissue. This supports the hypothesis that a reduction in energy demand, which is now equated with an increased ATP to ADP ratio in the sarcoplasm, is a critical component of the mechanism of cardioprotection in preconditioned myocardium. It is hypothesized that during PC or diazoxide treatment, the passage of the summation operatorAd into and out of the mitochondria is slowed, limiting the level of ATP available to the mitochondrial ATPase and preserving ATP and the total summation operatorAd. Altered ischemic mitochondrial metabolism plays an important role in establishing and maintaining the preconditioned state.

The effects of dietary hempseed on cardiac ischemia/reperfusion injury in hypercholesterolemic rabbits

BACKGROUND

Hempseed is a novel functional food that contains several health-promoting polyunsaturated fatty acids (PUFAs). PUFAs, such as those found in flaxseed and fish, have been shown to protect the heart against arrhythmias following ischemia/reperfusion.

OBJECTIVE

TO INVESTIGATE THE POTENTIAL OF DIETARY HEMPSEED AS A CARDIOPROTECTIVE AGENT AGAINST GLOBAL ISCHEMIA AND SUBSEQUENT REPERFUSION BY ASSESSING SEVERAL MEASUREMENTS OF CARDIAC PERFORMANCE: QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration.

METHODS

MALE NEW ZEALAND WHITE RABBITS WERE FED ONE OF SIX DIETS: a control diet; or one supplemented with 10% hempseed, 10% delipidated hempseed, 0.5% cholesterol, 0.5% cholesterol plus 10% hempseed or 5% coconut oil. After eight weeks on their respective diets, the hearts were excised and subjected to 30 min of global ischemia and 45 min of reperfusion. Electrocardiogram traces were recorded throughout the experiment and were subsequently analyzed for QT interval duration, left ventricular pressure, arrhythmia incidence and arrhythmia duration. Plasma and cardiac tissue were analyzed for fatty acid content and composition.

RESULTS

Cholesterol-fed animals exhibited significantly higher PUFA levels in their plasma, but this did not directly translate into higher PUFA levels in their cardiac fractions. There were no significant differences among the groups in the incidence or duration of ischemia-derived arrhythmias. During reperfusion, there was a significant decrease in the incidence of fibrillation in the hearts obtained from cholesterol-fed and hempseed- plus cholesterol-fed rabbits compared with the hearts from delipidated hempseed-fed rabbits.

CONCLUSIONS

Dietary hempseed induced limited beneficial effects on cardiac function during ischemia/reperfusion challenge. The present study does not support the use of dietary hempseed to protect the heart during ischemic insult in this experimental model.

Acid fibroblast growth factor reduces rat intestinal mucosal damage caused by ischemia-reperfusion insult

AIM: To detect the effects of acid fibroblast growth factor (aFGF) on apoptosis and proliferation of intestinal epithelial cells in differentiation or proliferation status to explore the protective mechanisms of aFGF.

METHODS: Wistar rats were randomly divided into sham-operated control group (C, n = 6), intestinal ischemia group (I, n = 6), aFGF treatment group (A, n = 48) and intestinal ischemia-reperfusion group (R, n = 48). Apoptosis of intestinal mucosal cells was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) technique. Proliferating cell nuclear antigen (PCNA) protein expression and distribution were detected with immunohistochemical method. Plasma levels of D-lactate were determined with modified Brandts method.

RESULTS: In A group, administration of exogenous aFGF could improve intestinal histological structure and decrease plasma D-lactate levels at 2-12 h after the reperfusion compared with R group. The apoptotic rates and PCNA protein expressions were not increased until 2 h after reperfusion and were maximal at 12 h. After reperfusion for 2-12 h, the apoptotic rates were gradually augmented along the length of jejunal crypt-villus units. Administration of aFGF could significantly reduce the apoptotic response at 2-12 h after reperfusion (P<0.05). Apoptosis rates in villus and crypt epithelial cells in A group at 12 h after reperfusion were (62.5±5.5)% and (73.2±18.6)% of those in R group, respectively. Treatment of aFGF could apparently induce protein expression of PCNA in intestinal mucosal cells of A group compared with R group during 2-12 h after reperfusion (P<0.05). There were approximately 1.3- and 1.5-times increments of PCNA expression levels in villus and crypt cells in A group at 12 h after reperfusion compared with R group, respectively.

CONCLUSION: Intestinal I/R insult could lead to histological structure change and apoptotic rate increment. The protective effects of aFGF against ischemia/reperfusion in rat intestinal mucosa might be partially due to its ability to inhibit ischemia/reperfusion-induced apoptosis and to promote cell proliferation of crypt cells and villus epithelial cells.

Endogenous zinc in neurological diseases

The use of zinc in medicinal skin cream was mentioned in Egyptian papyri from 2000 BC (for example, the Smith Papyrus), and zinc has apparently been used fairly steadily throughout Roman and modern times (for example, as the American lotion named for its zinc ore, 'Calamine'). It is, therefore, somewhat ironic that zinc is a relatively late addition to the pantheon of signal ions in biology and medicine. However, the number of biological functions, health implications and pharmacological targets that are emerging for zinc indicate that it might turn out to be 'the calcium of the twenty-first century'. Here neurobiological roles of endogenous zinc is summarized.

Role of interleukin 18 in acute lung inflammation induced by gut ischemia reperfusion

AIM: To study the changes of endogenous interleukin 18 (IL-18) levels and evaluate the role of IL-18 on lung injury following gut ischemia/reperfusion.

METHODS: A superior mesenteric artery occlusion model was selected for this research. The mice were randomly divided into four groups: Sham operation (sham), ischemia (0.5 h) followed by different times of reperfusion (I/R), and I/R pretreated with exogenous IL-18 (I/R+IL-18) or IL-18 neutralizing antibody (I/R+IL-18Ab) 15 min before ischemia. Serum IL-18 levels were detected by Western blot and ELISA, and the levels of IL-18 in lung tissue were evaluated by immunohistochemical staining. For the study of pulmonary inflammation, the lung myeloperoxidase (MPO) contents and morphological changes were evaluated.

RESULTS: Gut ischemia/reperfusion induced rapid increase of serum IL-18 levels, peaked at 1 h after reperfusion and then declined. The levels of IL-18 in lung tissue were gradually enhanced as the progress of reperfusion. Compared with I/R group, exogenous administration of IL-18 (I/R+IL-18) further remarkably enhanced the pulmonary MPO activity and inflammatory cell infiltration, and in I/R+IL-18Ab group, the content of MPO were significantly reduced and lung inflammation was also decreased.

CONCLUSION: Gut ischemia/reperfusion induces the increase of IL-18 expression, which may make IL-18 act as an important proinflammatory cytokine and contribute to gut ischemia/reperfusion-induced lung inflammation.

Change of gene expression in intestinal epithelial cells under ischemia and anoxia in rats

AIM: To investigate the change of gene expression in intestinal epithelial cells (IECs) under ischemia and anoxia in rats and to search for the correlated genes with IECs injury.

METHODS: IECs injury model was induced by ischemia and anoxia, and the cells were divided into four groups: control group, ischemia group, anoxia group and ischemia and anoxia (I/A) group. Fluorescence reverse transcription was used to label mRNA. The cDNA microarray was used to detect the difference between gene expression of control group and experiment groups.

RESULTS: There were 207 genes differently expressed between control and ischemia group, of which 132 were down-regulated while 75 were up-regulated. One hundred and sixty-eight genes were differently expressed between control and anoxia group, of which 84 were down-regulated while 84 were up-regulated. Between control and I/A group, 321 genes were differently expressed, of which 97 were down-regulated while 224 were up-regulated.

CONCLUSION: cDNA microarray can be used to screen diversified gene expression related to injury under ischemia and anoxia, which brings some new clues for studying the mechanism of IECs injury.

Intravenous acid fibroblast growth factor protects intestinal mucosal cells against ischemia-reperfusion injury via regulating Bcl-2/Bax expression

AIM: To detect the effect of acid fibroblast growth factor (aFGF) on apoptosis and gene expression of bax and bcl-2 gene in rat intestine after ischemia/reperfusion (I/R) injury, and to explore the protective mechanisms of aFGF.

METHODS: One hundred and eight Wistar rats were randomly divided into sham-operated control group (C) (n = 6), intestinal ischemia group (I) (n = 6), aFGF treatment group (A) (n = 48) and intestinal ischemia-reperfusion group (R) (n = 48). In group I, the animals were killed after 45 min of superior mesenteric artery (SMA) occlusion, while in groups R and A, the rats sustained 45 min of SMA occlusion and were then treated with normal saline and aFGF, respectively, sustained 15 min, 30 min, 1, 2, 6, 12, 24, or 48 h of reperfusion, respectively. In group C, SMA was separated, but without occlusion. Apoptosis in intestinal villus was determined with terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeling technique (TUNEL). Intestinal tissue samples were taken not only for detection of bax and bcl-2 gene expression by RT-PCR, but also for detection of bax and bcl-2 protein expression and distribution by immunohistochemical analysis.

RESULTS: The rat survival rates in aFGF treated group were higher than group R (P<0.05) and the improvement of intestinal histological structures was observed at 2, 6, and 12 h after the reperfusion in group A compared with group R. The apoptotic rates were (41.17±3.49)%, (42.83±5.23)% and (53.33±6.92)% at 2, 6 and 12 h after reperfusion, respectively in group A, apparently less than those of group R at matched time points (50.67±6.95, 54.17±7.86, 64.33±6.47, respectively) (P<0.05). The bax gene transcription and translation were significantly decreased in group A vs group R, while mRNA and protein contents of Bcl-2 in group A were obviously higher than those in group R during 2-12 h period after reperfusion.

CONCLUSION: The changes in histological structure and the increment of apoptotic rate indicated that the intestinal barrier was damaged after intestinal I/R injury, whilst intravenous aFGF could alleviate apoptosis induced by ischemia and reperfusion in rat intestinal tissues, in which genes of bax and bcl-2 might play important roles.

Computed tomography findings in fatal cases of enormous hepatic portal venous gas

AIM: To assess the computed tomography (CT) findings in the patients with hepatic portal venous gas (HPVG) who presented with a short fatal clinical course in our hospital in order to demonstrate if there was any sign for prediction.

METHODS: Between January 1997 and December 2000, CT scan of the abdomen was performed on 949 patients with acute abdominal pain in our emergency department. Five patients were found having HPVG. The CT images and clinical presentations of all these five patients were reviewed.

RESULTS: In reviewing the CT findings of the cases, HPVG in bilateral hepatic lobes, abnormal gas in the superior mesenteric veins, small bowel intramural gas, and bowel distension were observed in all patients. Dry gas in multiple branches of the mesenteric vein was also revealed in all cases. All the patients expired due to irreversible septic shock within 48 h after their initial clinical presentation in emergency room. Two patients had acute pancreatitis with grade D and E Balthazar classification and they expired within 24 h due to progressing septic shock under aggressive medical treatment and life support. Two patients with underlying end stage renal disease expired within 48 h even though emergent surgical intervention was undertaken. The excited bowels revealed severe ischemic change. One patient expired only a few hours after the CT examination.

CONCLUSION: HPVG is a diagnostic clue in patients with acute abdominal conditions, and CT is the most specific diagnostic tool for its evaluation. The dry mesenteric veins are the suggestive fatal sign, especially for the deteriorating patients, with the direct effect on gastrointestinal perfusion.

Anomalous flexor digitorum superficialis muscle transposition for vascular coverage of the median nerve in recurrent carpal tunnel syndrome

Recurrent carpal tunnel syndrome is uncommon yet troublesome. Significant adhesions and scarring around the median nerve can render it relatively ischemic. A number of vascular flaps have been described to provide vascular coverage in attempts to decrease further cicatricial adhesions and to improve local blood supply around the median nerve. A rare case of an anomalous muscle in the distal forearm used as tissue to provide good vascularized coverage of the median nerve that was severely scarred in its bed is reported. The anomalous muscle was distal to the flexor digitorum superficialis tendon and inserted in the palmar fascia on the ulnar aspect of the hand. Referring branches from the ulnar artery provided vascular supply to the anomalous muscle. The muscle on these vascular pedicles was transposed over the median nerve, providing good, stable, unscarred coverage. The patient had an excellent result with resolution of the carpal tunnel symptoms. The redundant anomalous muscle provided a unique vascularized source for coverage of the median nerve in recurrent carpal tunnel syndrome.

Influence of ischemia and anoxia on distribution and polarity of integrin in intestine epithelial cells

AIM: To study the influence of ischemia and anoxia injury on the distribution and polarity of integrin in intestine epithelial cells (IEC).

METHODS: IEC ischemia and anoxia injury model was established. The cells were divided into four groups, namely, group A (control group), group B (anoxia group), group C (ischemia group), and group D (ischemia and anoxia group). Cell apoptosis and the polarity and distribution of integrins a3, a5, b1, b2, b5 were determined by flow cytometry (FCM) and laser scanning confocal microscope (LSCM), respectively.

RESULTS: Integrins a3, a5, b1, b5 were expressed exclusively on the basal and lateral surfaces of IECs in group A. After ischemia and anoxia injury, integrins a3, a5, b1, b5 distribution moved from the basolateral to the apical membrane. Cell apoptosis was increased in group B, C and D. Integrin a3 was not observed in the middle and apical membrane in group C. Integrin b2 distribution was not markedly changed in any group.

CONCLUSION: The change in the distribution of integrin is induced by ischemia and anoxia, which is correlated with IEC apoptosis. IEC apoptosis is more sensitive to the anoxia.

Ischemic preconditioning and diazoxide limit mitochondrial Ca overload during ischemia/reperfusion: Role of reactive oxygen species

BACKGROUND

Generation of reactive oxygen species (ROS) is associated with cardioprotection imparted by ischemic preconditioning (IPC) and pharmacological PC (PPC). The authors have previously shown that IPC or PPC, using the mitochondrial ATP-sensitive K(+) channel opener diazoxide (DZ), reduce mitochondrial Ca(2+) ([Ca(2+)](m)) during ischemia and reperfusion.

OBJECTIVES

To test the hypothesis that both IPC and PPC (using DZ) lead to reduced [Ca(2+)](m) and improved functional recovery via a ROS-dependent mechanism.

METHODS

Intracellular Ca(2+) ([Ca(2+)](i)) and [Ca(2+)](m) were measured in isolated perfused rat hearts loaded with the fluorescent indicator indo-1 acetoxymethyl ester. [Ca(2+)](m) was determined by quenching the cytosolic indo-1 signal using manganese before ischemia (25 min). IPC and DZ (100 muM) group hearts were studied with and without the ROS scavenger N-2-mercaptopropionyl glycine (400 muM) (2-MPG).

RESULTS

Both IPC and DZ significantly reduced [Ca(2+)](i) and [Ca(2+)](m) on reperfusion compared with the control. Administration of 2-MPG with washout before ischemia significantly attenuated the reduction in [Ca(2+)](m) observed on reperfusion in both the IPC and DZ groups. Additionally, the myocardial functional protection imparted by IPC or DZ was lost with the administration of 2-MPG.

CONCLUSIONS

The [Ca(2+)](m)-reducing effect of IPC and DZ was attenuated with the administration of 2-MPG, resulting in decreased myocardial functional performance and increased release of creatine kinase, a marker of cellular injury. It can be concluded that IPC and DZ impart their protective effect via a mechanism involving ROS generation before the ischemic episode.

A common mechanism in the protective effects of preconditioning, cardiac pacing and physical exercise against ischemia and reperfusion-induced arrhythmias

Ischemic preconditioning results not only in a reduction in myocardial ischemic damage, but also in a marked suppression of those ventricular arrhythmias that result from a more prolonged period of ischemia and reperfusion insult. This protection is time-dependent and occurs in two distinct phases. There is an 'early phase' which is apparent immediately after the preconditioning stimulus but fades quickly (within 1 h to 2 h), and a 'delayed protection phase' in which the antiarrhythmic protection reappears 20 h to 24 h later. In both phases, the intensity of protection largely depends on the nature of the preconditioning stimulus. This can be ischemia resulting from brief coronary artery occlusions, cardiac pacing or vigorous physical exercise. Both cardiac pacing and exercise results in a marked reduction in the incidence and severity of ischemia and reperfusion-induced ventricular arrhythmias 24 h later. Although the precise mechanisms of the delayed protection that results from cardiac pacing and exercise are not yet fully understood, there is some evidence that similar endogenous protective substances (such as bradykinin, prostanoids and nitric oxide), as with ischemic preconditioning, play a pivotal trigger and mediator role in this anti-arrhythmic protection.

Skin wound healing, ischemia-reperfusion injury and nerve regeneration: Similarities in the sequential events and molecular basis

Skin wound healing, ischemia-reperfusion injury and nerve regeneration are three important topics for the hand surgeon. The events and molecular basis for each of these three topics are very complex, and previous review articles have discussed each topic separately. The present review demonstrates and comments on the similarities in the sequential events and molecular basis among skin wound healing, ischemia-reperfusion injury and nerve regeneration.

D-ribose aids congestive heart failure patients

Patients with congestive heart failure often experience fatigue despite intensive pharmacological therapy. Ribose can aid the recovery of ATP levels and, hence, diastolic function. Clinical trials have shown that ribose supplementation improves ischemic threshold and enhances diastolic function in congestive heart failure.

Loss of cardioprotection induced by ischemic preconditioning after an initial ischemic period in isolated rat hearts

BACKGROUND

The beneficial effect of ischemic preconditioning (PC) has been extensively studied in normal hearts but its effects on diseased hearts remain largely unknown. The effect of PC in the already ischemic myocardium has not been previously studied, although ischemia in varying intervals, which is difficult to assess, is often encountered in clinical practice.

OBJECTIVE

To investigate whether the cardioprotective effect of PC is preserved when it is applied after a period of ischemia of varying duration.

METHODS

Male Wistar rats were used for this study. Isolated normal rat hearts were perfused in Langendorff mode. Before 20 min of zero flow global ischemia followed by 45 min of reperfusion, hearts were subjected to an initial 20-min period of ischemia followed by 10 min of reperfusion (group A1); an initial 20-min period of ischemia followed by 10 min of reperfusion and two-cycle PC (3 min of ischemia, 5 min of reperfusion followed by 5 min of ischemia and 5 min of reperfusion) (group A2); and two-cycle PC followed by the initial 20-min period of ischemia and 10 min of reperfusion (group A3). Groups B and C were subjected to an initial ischemia of 15 min and 10 min, respectively, and subgroups 1, 2 and 3 were treated as above. Left ventricular end-diastolic pressure was measured at 45 min of reperfusion (LVEDP45 in mmHg). Postischemic recovery of left ventricular developed pressure was expressed as a percentage of the initial value (LVDP%).

RESULTS

LVDP% and LVEDP45 were similar between groups A1 and A2, while when ischemic preconditioning preceded the two periods of ischemia (group A3), it resulted in significantly higher LVDP% and significantly lower LVEDP45 compared with groups A1 and A2. Left ventricular functional recovery was not increased in group B2 compared with group B1. LVDP% and LVEDP45 were similar among groups C1, C2 and C3.

CONCLUSION

Ischemic preconditioning does not improve functional recovery in isolated rat hearts that have been initially subjected to 20 min or 15 min of zero-flow global ischemia, while an initial 10-min ischemic period seems to precondition the heart.

Comparison of the effects of different magnesium administration times on infarct size

BACKGROUND

The protection of high magnesium on infarct size remains controversial.

OBJECTIVE

To examine the effects of magnesium administered before ischemia or early in reperfusion on infarct size in a rat model of global ischemia

METHODS

Isolated rat hearts were submitted to 40 min of normothermic global ischemia and 2 h of reperfusion. After 20 min of stabilization, four protocols were performed: ischemic control (IC) hearts; 15 mM of magnesium chloride administered 15 min before ischemia (MgI); 15 mM of magnesium chloride administered during the first 15 min of reperfusion (MgR); or 15 mM magnesium plus 5 mM calcium (Mg+Ca) before ischemia. Infarct size was measured by triphenyltetrazolium staining. Contractile function was assessed by left ventricular developed pressure and the maximal velocity of rise of left ventricular presssure.

RESULTS

The infarct size in IC hearts was 44+/-5%. In MgI and MgR hearts, the infarct diminished to 4.5+/-1.5% and 18+/-4%, respectively. In Mg+Ca hearts, the protection was also obtained (19+/-3%). Myocardial function also improved significantly by magnesium treatment. At the end of reperfusion, left ventricular developed pressure and maximal velocity of rise of left ventricular pressure values were 23+/-6% and 22+/-3% in MgI; and 10+/-3% and 9+/-2.6% in MgR versus 2+/-0.7% and 2.3+/-0.8% in IC hearts, respectively.

CONCLUSION

The treatment with magnesium either before ischemia or early in reperfusion has an infarct size limiting effect in a model of global ischemia. This protective effect is partially due to its calcium antagonistic action.

Factors determining heterogeneity in coronary collateral development: A clinical perspective

The mechanisms responsible for collateral development have attracted considerable attention in cellular and molecular research because these vessels have the capacity to protect against myocardial infarction and reduce exercise-induced ischemia. This has led to a number of phase I trials employing angiogenic peptides, genes and cell transplantation. However, there are significant differences in the degree of collateral development among patients even with similar patterns of coronary disease. Understanding the factors responsible for this heterogeneity has important implications for the efficacy of future therapeutic strategies. Therefore, this review will examine these factors from the clinical perspective integrating the clinical evidence with recent molecular and cellular studies. The role of specific pharmacological agents and novel investigational strategies will be discussed.

Leukocyte CD11a expression and granulocyte activation during experimental myocardial ischemia and long lasting reperfusion

BACKGROUND

Myocardial ischemia and reperfusion are accompanied by leukocyte activation and expression of surface adhesion molecules, which induce pathological interactions between endothelial cells and circulating neutrophils, leading to tissue damage. While the dynamics of these processes have been well defined during acute reperfusion, there is very little information regarding long lasting reperfusion.

OBJECTIVES

To investigate neutrophil granulocyte (PMN) activation and the CD11a expression of leukocytes during myocardial ischemia and reperfusion for four weeks.

ANIMALS AND METHODS

The left anterior descending coronary artery was occluded for 1 h in six dogs, followed by reperfusion for four weeks. Peripheral blood samples were collected before the operation, at the end of ischemia, at 5 and 60 min of reperfusion, and on postoperative days 1, 2, 3, 7, 14, 21 and 28. Sham operation on four dogs served as control. Leukocyte expression of CD11a was measured by flow cytometry. Superoxide radical production of isolated PMNs was determined spectrophotometrically.

RESULTS

Granulocyte CD11a expression increased while the superoxide radical-producing capacity decreased significantly by the third postoperative day. Sham operation produced similar alterations in these parameters during the first postoperative week. From the second postoperative week, however, granulocyte radical production and adhesion molecule expression were higher in the ischemic animals.

CONCLUSIONS

The exhaustion of PMN radical production and maximal CD11a expression during the first postoperative week are probably due to the surgical trauma caused by thoracotomy, but increased granulocyte function during later reperfusion indicates prolonged healing of injured myocardium.

Value of QT dispersion in evaluating spatial dispersion of ventricular repolarization during acute myocardial ischemia

OBJECTIVES

To study the value of epicardial QT interval dispersion in predicting ischemia-induced heterogeneity of ventricular repolarization.

ANIMALS AND METHODS

Ischemia was produced by total occlusion of the obtuse branch of the circumflex coronary artery in seven open-chest sheep. A 64-channel electrocardiogram (ECG) was acquired from the epicardium before and after coronary artery occlusion. Wavelet transformation was used to determine the characteristic points of the epicardial ECGs, and to measure the QT interval and activation-recovery interval (ARI) and their dispersions.

RESULTS

The average QT interval and ARI from the epicardial ECG were not changed by acute myocardial ischemia (P=0.07 and P=0.13, respectively). QT dispersion remained unchanged during ischemia (P=0.17), whereas ARI dispersion was significantly increased by acute ischemia (59.9+/-24.0 ms versus 126.3+/-32.1 ms, P<0.001).

CONCLUSIONS

These findings indicate that epicardial QT dispersion is less sensitive than ARI dispersion in estimating repolarization heterogeneity induced by acute myocardial ischemia.

Is the protection against ischemia induced by red wine linked to its antioxidant capacity?

OBJECTIVE

To establish whether the total antioxidant capacity of nonalcoholic extracts of three Argentine red wines (RWE) is correlated with their protection against ischemia-reperfusion injury.

ANIMALS AND METHODS

The antioxidant properties of three RWE were determined using different free radical-generating systems. To examine the effects of these RWE during a 20 min global ischemic period followed by 30 min of reperfusion, isolated rat hearts received 50 mug/mL of RWE 1 (cabernet-sauvignon), RWE 2 (malbec) or RWE 3 (a commercial mixture of cabernet-sauvignon, malbec and merlot) 10 min before and after ischemia. Left ventricular developed pressure (LVDP), maximal velocity of rise of left ventricular pressure (+dP/dt(max)) and left ventricular end-diastolic pressure (LVEDP) were used to assess contractility and diastolic function.

RESULTS

All RWE inhibited lipid peroxidation induced by the Cl(4)C/NADPH system in a similar proportion (42+/-4%, 47+/-9% and 43+/-14% for RWE 1, RWE 2 and RWE 3, respectively). The scavenging activity of superoxide anion and 2,2-diphenyl-1-picryl-hydrazyl radical was about the same with the three RWE. In hearts without RWE treatment, LVDP and +dP/dt(max) were 61+/-4% and 62+/-5%, respectively, at the end of the reperfusion period. Infusion of RWE 1 and RWE 2 significantly improved postischemic recovery (LVDP and +dP/dt(max) were 102+/-4% and 101+/-4% for RWE 1 and 92+/-5% and 91+/-5% for RWE 2, respectively) and attenuated the increase of LVEDP. RWE 3 did not improve either systolic or diastolic dysfunction.

CONCLUSION

These data show that although the three non-alcoholic RWE exhibit a similar total antioxidant capacity, only two of them protect the heart against myocardial stunning, suggesting that the protective effect is not primarily linked to the anti-oxidant properties of the extracts.

Occupational class and ischemic heart disease mortality in the United States and 11 European countries

OBJECTIVES

Twelve countries were compared with respect to occupational class differences in ischemic heart disease mortality in order to identify factors that are associated with smaller or larger mortality differences.

METHODS

Data on mortality by occupational class among men aged 30 to 64 years were obtained from national longitudinal or cross-sectional studies for the 1980s. A common occupational class scheme was applied to most countries. Potential effects of the main data problems were evaluated quantitatively.

RESULTS

A north-south contrast existed within Europe. In England and Wales, Ireland, and Nordic countries, manual classes had higher mortality rates than nonmanual classes. In France, Switzerland, and Mediterranean countries, manual classes had mortality rates as low as, or lower than, those among nonmanual classes. Compared with Northern Europe, mortality differences in the United States were smaller (among men aged 30-44 years) or about as large (among men aged 45-64 years).

CONCLUSIONS

The results underline the highly variable nature of socioeconomic inequalities in ischemic heart disease mortality. These inequalities appear to be highly sensitive to social gradients in behavioral risk factors. These risk factor gradients are determined by cultural as well as socioeconomic developments.

Myocardial infarction and stroke in young women: what is the impact of oral contraceptives?

Recent discussions have centered on the small apparent risk increase for venous thromboembolism found with newer oral contraceptives (third-generation oral contraceptives containing the progestins desogestrel and gestodene) compared with older oral contraceptives (second-generation). This article reviews the studies addressing the association between oral contraceptive use and thromboembolic conditions affecting the arterial system, ischemic stroke, and myocardial infarction. Differences are found between a US database study, which showed no risk of ischemic stroke or myocardial infarction associated with low-dose oral contraceptive use, and the European studies, which showed oral contraceptive use in general to be associated with increased risks of ischemic stroke and myocardial infarction. The European studies showed no difference between oral contraceptive generations with respect to the occurrence of ischemic stroke; however, the risk of myocardial infarction associated with oral contraceptive use was consistently lower for third- than for second-generation oral contraceptives. Although there seems to be no differential risk of ischemic stroke associated with oral contraceptive generations, third-generation oral contraceptives appear to be consistently associated with no excess risk of myocardial infarction. In all instances, however, cardiovascular risk factors other than oral contraceptive use play the predominant role in the occurrence of ischemic stroke and myocardial infarction.

Ischemic heart disease and alcohol-related causes of death: a view of the French paradox

PURPOSE

In France the low rates of death due to ischemic heart disease have been attributed to the high consumption of alcohol. However, the question remains: are the higher death rates for causes associated with alcohol consumption an explanation?

METHODS

Diseases were defined according to the International Classification of Diseases, revision 9. World Health Organization data on country- and age-specific death rates were used.

RESULTS

Official causes-of-death statistics for men 40-74 years of age show that in 1990 French men under 50 years old had low death rates from ischemic heart disease but a relatively high all-cause mortality rate, in contrast to low rates for men 60 to 74 years of age. Among French men aged 40-44 years in 1960, 34% had died before reaching the age of 70-74 years. In comparison, 37% in the United States and 36% in England and Wales, had died by this age, with 4.5%, 14.1%, and 15.2% of deaths, respectively, due to ischemic heart disease. If all of the men who died early of causes associated with alcohol had died of ischemic heart disease, there would still be a lower rate in France (21%) than in the United States (26%) or in England and Wales (25%).

CONCLUSION

Thus, although some of the chronic heavy drinkers in France die early of causes associated with excessive alcohol consumption, this is not the only reason for the low ischemic heart disease death rates.

Amrinone improves postischemic myocardial metabolism in the rat heart-lung preparation

Amrinone, a phosphodiesterase inhibitor, is a non-glycosidic noncatecholamine with both vasodilator and positive inotropic effects. We were interested in assessing the effect of amrinone on postischemic cardiac performance in the isolated heart-lung preparation. Twenty-four male Wistar-ST rats were used. They were randomly divided into three groups. Amrinone, 10 μg·ml^-1 or 100 μg·ml^-1 was administered 8 min after the start of perfusion except in the control group. Ten minutes after the start of perfusion, all hearts were made globally ischemic for 8 min. Subsequently, the preparations were reperfused for 10 min. At the end of the experimental period, the hearts were freeze-clamped, and then myocardial high-energy phosphates, lactate, pyruvate, and glycogen were measured. Hemodynamic parameters in all groups decreased significantly during ischemia. However, there were no significant differences among the groups. The myocardial ATP level in the 100 μg·ml^-1 group was significantly higher than that in the control group. Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) levels in the 100 μg·ml^-1 group were significantly lower than those in the control group. Myocardial lactate, pyruvate, and glycogen levels were not significantly different among the groups. This result suggests that amrinone improves postischemic myocardial metabolism. Although we could not measure coronary flow, amrinone might increase coronary flow with direct coronary vasodilation which would have increased the myocardial ATP and energy charge levels.

Stroke in users of low-dose oral contraceptives

BACKGROUND

Previous studies have linked the use of oral contraceptive agents to an increased risk of stroke, but those studies have been limited to oral contraceptives containing more estrogen than is now generally used.

METHODS

In a population-based, case-control study, we identified fatal and nonfatal strokes in female members of the California Kaiser Permanente Medical Care Program and who were 15 through 44 years of age. Matched controls were randomly selected from female members who had not had strokes. Information about the use of oral contraceptives (essentially limited to low-estrogen preparations) was obtained in interviews.

RESULTS

A total of 408 confirmed strokes occurred in a total of 1.1 million women during 3.6 million woman-years of observation. The incidence of stroke was thus 11.3 per 100,000 woman-years. On the basis of data from 295 women with stroke who were interviewed and their controls, the odds ratio for ischemic stroke among current users of oral contraceptives, as compared with former users and women who had never used such drugs, was 1.18 (95 percent confidence interval, 0.54 to 2.59) after adjustment for other risk factors for stroke. The adjusted odds ratio for hemorrhagic stroke was 1.14 (95 percent confidence interval, 0.60 to 2.16). With respect to the risk of hemorrhagic stroke, there was a positive interaction between the current use of oral contraceptives and smoking (odds ratio for women with both these factors, 3.64; 95 percent confidence interval, 0.95 to 13.87).

CONCLUSIONS

Stroke is rare among women of childbearing age. Low-estrogen oral-contraceptive preparations do not appear to increase the risk of stroke.