Effect of a glutathione S-transferase inhibitor on oxidative stress and ischemia-reperfusion-induced apoptotic signalling of cultured cardiomyocytes

Oxidative stress and ischemia-reperfusion (I/R) injury are crucial in the pathogenesis of cardiovascular diseases. The antioxidant glutathione S-transferase (GST) is responsible for the high-capacity metabolic inactivation of electrophilic compounds and toxic substrates. The main objective of the present study was to examine the effect of GST inhibition (with the administration of ethacrynic acid [EA]) on the viability and apoptosis of cardiomyocytes when these cells are exposed to various stress components of I/R and mitogen-activated protein kinase (c-Jun N-terminal kinase, p38 and extracellular signal-regulated kinase [ERK]) inhibitors. The primary culture of neonatal rat cardiomyocytes was divided into six experimental groups: control group of cells (group 1), cells exposed to H(2)O(2) (group 2), I/R (group 3), I/R and EA (group 4), H(2)O(2) coupled with EA (group 5), and EA alone (group 6). The viability of cardiomyocytes was determined using a colorimetric MTT assay. The apoptosis ratio was evaluated via fluorescein isothiocyanate-labelled annexin V and propidium iodide staining. c-Jun N-terminal kinase, p38, Akt/protein kinase B and ERK/p42-p44 transcription factors were monitored with flow cytometry. c-Jun N-terminal kinase activation increased due to GST inhibition during I/R. EA administration led to a significant increase in p38 activation following both H(2)O(2) treatment and I/R. ERK phosphorylation increased when GST was exposed to I/R. A pronounced decrease in Akt phosphorylation was observed when cells were cotreated with EA and H(2)O(2). GST plays an important role as a regulator of mitogen-activated protein kinase pathways in I/R injury.

Changes and effect of PACAP-38 on intestinal ischemia-reperfusion and autotransplantation

Tissue injury caused by cold preservation and reperfusion during small bowel transplantation remains an unsolved problem. Increasing evidence suggests that pituitary adenylate cyclase-activating polypeptide (PACAP) has protective effects in several ischemia-reperfusion (I/R) models. This study investigated the effect of PACAP-38 on oxidative stress in autotransplanted intestine. We established sham-operated, I/R, and autotransplanted groups in Wistar rats (n = 55). We applied ischemia for 1 (GI), 2 (GII), or 3 hours (GIII). In autotransplanted groups, we performed total orthotopic intestinal autotransplantation. Grafts were preserved in University of Wisconsin (UW) solution for 1 (GIV), 2 (GV), 3 (GVI), or 6 (GVII) hours and in PACAP-38-containing UW for 1 (GVIII), 2 (GIX), 3 (GX), or 6 (GXI) hours. Reperfusion lasted 3 hours in each group. Endogenous PACAP-38 values were measured by radioimmunoassay. Oxidative stress parameters malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) were measured in tissue homogenates. Concentration of endogenous PACAP-38 significantly decreased in GI to GIII compared with the sham-operated animals following I/R periods (P < .05). Cold preservation in UW and reperfusion of the intestine increased the level of tissue MDA in GIV to GVII, which correlated with the duration of cold storage. The content of GSH decreased in GIV to GVII to levels that were significantly different between GIV and GVIII and between GVII and GXI. SOD activity decreased dramatically in GIV to GVII with significantly higher activity in GIX to GXI. Our findings confirmed that I/R decreased endogenous PACAP-38 concentration. Administration of PACAP-38 to UW solution mitigated the oxidative injury during intestinal autotransplantation.

Effect of hyaluron derivate gel in prevention of postsurgical peritoneal adhesions--an experimental study in pigs

BACKGROUND/AIMS

The aim of this study was to assess the efficacy of a hyaluronic acid derivate gel in reducing adhesions in pigs undergoing laparoscopic abdominal cavity surgery.

METHODOLOGY

20 domestic female pigs underwent laparoscopy in general anesthesia. 4 defined serosal defects have been made (hepatoduodenal ligament, parietal, anterior stomach wall and jejunal mesentery). The defects have been covered with 20 mL Hyalobarrier Gel in 10 randomly selected pigs. 2 weeks postoperatively the pigs got reoperated for evaluation of potential adhesions.

RESULTS

17 pigs remained for evaluation. 2 pigs died during introduction of anesthesia, one at the end of the operation. None of the pigs died due to a reaction to the gel. We found adhesions in 33% of the gel group (n=3 out of 9) and in 87.5% in the group without gel (7 out of 8): p < 0.05. Most of the adhesions have been found at the parietal defect (7 out of 17 at all).

CONCLUSIONS

The hyaluronic acid gel was highly efficacious and reduced the number and extent of adhesions throughout the abdomen following laparoscopic peritoneal surgery significantly.

Threshold Level of NF-kB Activation in Small Bowel Ischemic Preconditioning Procedure

Ischemic preconditioning (IPC), which is obtained by exposure to brief periods of vascular occlusion, improves organ tolerance to prolonged ischemia. The aim of this study was to evaluate the threshold level of NF-kB activation in small intestine during an IPC procedure. Various intestinal IPC were performed on 20 Wistar rats in seven groups: group I (GI, nonpreconditioned); group II (GII, 1-minute ischemia and 1-minute reperfusion); group III (GIII, two cycles of 1-minute ischemia and 1-minute reperfusion); group IV (GIV, 2-minutes ischemia and 2-minutes reperfusion); group V (GV, two cycles of 2-minute ischemia and 2-minute reperfusion); group VI (GVI, 5-minute ischemia and 10-minute reperfusion); group VII (GVII, two cycles of 5-minute ischemia and 10-minute reperfusion). Bowel biopsies were collected after laparotomy (control) as well as at 30, 60, and 120 minutes following IPC. We determined the cytoplasmic and nuclear NF-kB by a chemiluminescence-based ELISA method. Our results showed low, constant NF-kB levels in GI. In the preconditioned groups (GII-GVII), NF-kB was significantly elevated at 30 minutes following IPC (P < .05 vs control). After 1 hour, NF-kB activity decreased to the control level. However, 2 hours after IPC both forms of NF-kB were elevated significantly again, which was independent of the number of IPC cycles (P < .05 vs control). Our experiments revealed that one cycle of 1-minute ischemia and 1-minute reperfusion is a critical threshold level for NF-kB activation during small bowel IPC. Longer and more IPC cycles did not result in further elevation of NF-kB activation.

Laparoscopic Azygoportal Disconnection Procedure with a Bipolar Feedback Controlled Sealing System in a Porcine Model1

BACKGROUND

To examine the feasibility of a new, minimally invasive procedure for the devascularization of the proximal stomach and distal esophagus to prevent recurrent variceal bleeding in portal hypertension in a new animal model.

MATERIAL AND METHODS

Portal hypertension was created by laparoscopic clip ligation of the portal vein on 20 pigs. After 2 weeks the azygoportal disconnection procedure was performed with the LigaSure-ATLAS instrument.

RESULTS

There were 16 pigs out of 20 that survived both operations. Two died during introduction of anesthesia, one because of a cardiac arrest (second operation). One pig died resulting from necrosis of the gastric and esophageal wall. Autopsy (2 weeks later) showed that there was a complete arterial devascularization. At autopsy, none of the remaining 16 pigs had esophageal varices or necrosis of the stomach or esophagus.

CONCLUSION

Laparoscopic azygoportal disconnection is a less invasive method for the prevention of rebleeding and seems to be safely performed with the LigaSure-ATLAS instrument.

Bradykinin and angiotensin-converting enzyme inhibition in cardioprotection

OBJECTIVES

To show that angiotensin-converting enzyme (ACE) inhibition potentiates subthreshold ischemic preconditioning (IPC) via the elevation of bradykinin activity, leading to a fully delayed cardioprotective response.

METHODS

On day 1 of the experiment, pigs were subjected to sham (group 1, controls) or IPC protocols. In groups 2 and 3, 4x5 min and 2x2 min of IPC, respectively, were elicited by occluding the left anterior descending coronary artery with percutaneous transluminal coronary angioplasty inflatable balloon catheter. Group 4 was subjected to the ACE inhibitor perindoprilate only. In group 5, the pigs were pretreated with perindoprilate (0.06 mg/kg) and then subjected to 2x2 min IPC. In group 6, intracoronary HOE 140 (a selective bradykinin B(2) receptor antagonist) was added before the perindoprilateaugmented subthreshold (2x2 min) PC stimulus. On the second day, all animals underwent 40 min left anterior descending coronary artery ligation and 3 h reperfusion, followed by infarct size analysis using triphenyl tetrazolium chloride staining.

RESULTS

THE RATES OF INFARCT SIZE AND RISK ZONE WERE THE FOLLOWING IN THE EXPERIMENTAL GROUPS: group 1, 42.8%; group 2,19.5% (P<0.05); group 3, ischemia/reperfusion (I/R) 33.4%; group 4, I/R 18.4% (P<0.05); group 5, I/R 31.2%; and group 6, I/R 36.3%. A significant increase of nuclear factor kappa B activation in groups 2 and 4 was seen.

CONCLUSIONS

Results confirm that ACE inhibitors do not give total pharmacological IPC, but they enhance the induction effect of small ischemic insults, which raises the ischemic tolerance of myocardium. It was determined that enhanced bradykinin activity leads to downstream nuclear factor kappa B activation in this model.

The role of free radicals in endogenous adaptation and intracellular signals

Oxidative stress can generate a mass of oxygen free radicals (OFR) in the cells, and these OFRs can induce several acute and chronic symptoms and diseases. If the amount of the generated OFRs overwhelms the antioxidant capacity of the cells, the pathophysiological changes may lead to the death of the cell or the development of chronic degenerative diseases.The phenomenon of ischemic preconditioning has demonstrated the important role of these aggressive and harmful molecules in the endogenous adaptation mechanism of the cells to oxidative stress. After sublethal oxidative stress - mild ischemic insult - the resulting development of a few OFRs can stimulate the intracellular signal-transduction cascade of ischemic preconditioning and, through the induction of severe transcription factors, new antioxidant enzymes and heat shock proteins will be synthesized. These newly synthesized proteins will protect the cellagainst another, more serious oxidative insult in the future.

[Partial replacement of the trachea with jejunal autograft in the dog]

Extensive lesions of the cervical trachea can occur as a result of malformation, inflammation, tumor disease or trauma. If a short segment of the trachea is resected primary anastomosis may be possible. The problem of how to treat lesions longer than 50% of total tracheal length is still unresolved. The aim of our study was to clarify the possible use and limitations of small bowel interposition for tracheal replacement in veterinary model. We resected 6 cm of the cervical trachea of 5 adult mongrel dogs. Autolog jejunum free flap was used for replacement. The wall of the implant was supported with 5 polytetrafluoroethylene rings placed on the outer surface of the bowel perpendicular to its axis. We performed the surgery in two stages. Intraoperative tracheostomy was necessary in every case. The tracheal tube extended through the whole length of the implant. The survivals, the viability of the graft and complications were examined. The length of survival ranged between 18 h and 72 h. In one case obstruction of the tracheal tube occurred, in 3 cases the micro vessel anastomosis of the graft thrombosed, in one case both complications developed. In our experience use of the small bowel flap was complicated with fatal technical difficulties. The micro vessel anastomosis proved to be highly risky. Further investigations are needed to improve the results with this method.

Angiotensin-converting enzyme inhibition enhances a subthreshold stimulus to elicit delayed preconditioning in pig myocardium

OBJECTIVES

We assessed the effect of angiotensin-converting enzyme (ACE) inhibition in combination with a subthreshold preconditioning (PC) stimulus to elicit delayed preconditioning against infarction in pig myocardium.

BACKGROUND

Bradykinin triggers early PC. Angiotensin-converting enzyme inhibitors increase local bradykinin levels via inhibition of kinin breakdown and have been shown in experimental studies to augment early protection afforded by PC. A role for bradykinin in eliciting delayed PC has not so far been identified.

METHODS

We used a two-day protocol. On day 1 (closed chest), pigs were either sham-operated (group 1) or preconditioned, using balloon catheter inflation of the left anterior descending (LAD) coronary artery, with either a full (4 x 5 min PC, group 2) or subthreshold PC stimulus (2 x 2 min PC, group 3). Additional groups were pre-treated with perindoprilat (0.06 mg/kg i.v.) before sham (group 4) or subthreshold PC (group 5). On day 2 (open chest), all pigs were subjected to 40 min occlusion of the LAD followed by 3 h of reperfusion. Infarct size was determined by tetrazolium staining.

RESULTS

Group 1 had a mean infarct size of 42.8+/-3.2% of the risk zone. Preconditioning with 4 x 5 min reduced the infarct size to 19.5+/-3.9% (p < 0.05). Groups 3 and 4 had infarct sizes not statistically different from group 1. However, combining perindoprilat with subthreshold PC resulted in a significant limitation of the infarction (18.4+/-3.1% p < 0.05), comparable with group 2.

CONCLUSIONS

This is the first study to show that ACE inhibition can augment a mild ischemic stimulus to induce a protected state 24 h later.

[Monitoring of oxidative stress after experimental small bowel autotransplantation]

The difficulty at transplanting the small bowel mainly is caused by the biology of the intestine. It is highly immunogenic, is one of the most sensitive tissues to ischemia-reperfusion injury. Our aims were to investigate changes of oxygen free radical mediated reactions after autotransplantation at different preservation times and perfusion fluids. Our results prove that this model is feasible to examine ischemia-reperfusion injury in the small intestine. Euro Collins (EC) is a suitable preserving solution for small bowel transplantation. There was no significant lipid peroxidation within the first 6 hours of graft preservation. However superoxide dismutase (SOD) activity was dramatically reduced during reperfusion in the tissues samples. Significant increase of reduced glutathione at the same time can be explained by compensatory mechanism to neutralize increased free radical production.

[Effect of chronic anemia on the endothelium-dependent dilatation of the brachial artery]

The effect of changes in main determinants of whole blood viscosity after red blood cell transfusion on endethel dependent dilatation of brachial artery was studied in patients treated with transfusion because of symptoms of chronic anaemia.

PATIENTS AND METHODS

10 patients were involved, 8 females 2 males, mean age 50.9 +/- 16.6 years. Following blood tests were performed at hospital admission: hemoglobin, red blood cell count, heamatocrit, white blood cell count, platelet count, plasma total protein, fibrinogen, plasma viscosity, blood urea nitrogen, creatinine, cholesterol, triglicerides. Flow mediated dilatation of brachial artery was determined, too. Blood tests and flow mediated dilatation study were repeated after transfusion.

RESULTS

The main determinants of whole blood viscosity increased after transfusion. The increase of hemoglobin, red blood cell count, hematocrit were highly significant. The central flow velocity in brachial artery decreased at rest and during hyperemia as well. The flow mediated dilatation of brachial artery wasn't significantly changed by transfusion.

CONCLUSIONS

Change of determinants of whole blood viscosity caused by transfusion didn't change the flow mediated dilatation of brachial artery. The probable reason for this that the increase of whole blood viscosity in associated with the decrease of central flow velocity. These two counteracting changes probably equal each other.

[Surgical trauma induced by laparoscopic cholecystectomy]

The objective demonstration of improved postoperative recovery suggests that surgical injury induced by the laparoscopic approach is less intense than that after open surgery. Forty-two patients diagnosed as having noncomplicated gallstones were studied prospectively. They were operated on by laparoscopy (LC, n = 21) or open surgery (OC, n = 21). Both surgical procedures induced significant changes of investigated parameters (acute-phase response, free radical mediated reactions, neutrophil functions). Comparison of the results of the two cholecystectomy techniques showed that laparoscopic cholecystectomy induced a significantly less intense acute-phase response, a more attenuated oxidative stress characterising by free radical mediated reactions and that is less disruptive to neutrophil function. The results and the data from the literature suggest that surgical injury causing by the laparoscopic cholecystectomy is less intense than that after open cholecystectomy, which can explain partially the better clinical outcome following laparoscopic versus open procedure.

The values of detection of free radical mediated reactions in patients

The peroxidative processes and individual antioxidant protection were measured in patients with different cardiovascular diseases. We concluded that monitoring of this system we were able to detect not only the actual changes of lipid peroxidation and antioxidant defence mechanisms, but additionally the therapeutic efficacy of the treatment.

Haemarthros induced articular cartilage degradation

The statement that blood in the articular cavity is cause of cartilage degradation is widely accepted as an axiom. Although the causes of the different articular diseases were explained in numerous studies, none of them has clarified the pathomechanism of haemarthrosis. Our aims were: 1/ to give a morphological description of the blood induced changes in the cartilage, 2/ to verify that the haemarthros is the cause of the cartilage degradation. 10 white rabbits were used in our experimental model. Artificial haemarthros was produced in their left hind knees by intraarticular injection of their own blood. The right hind served as control. The rabbits were divided into to five groups based on the time of the haemarthros (22-50 days). Samples of the condylar cartilage were taken for light, polarization, transmission and scanning electron microscopy examinations. Signs of the disorganization of the matrix structure were showed by polarisation microscope and serious lesions were detected in the perichondrium by scanning electron microscope. Similarity have been suggested amongst the pathomechanism of haemarthrosis and other degenerative cartilage diseases (e. g.: osteoarthrosis, rheumatoid arthritis), so we made the same comparison. In many cases similar morphological changes were observed, as described by other authors in case of degenerative diseases.

Monitoring of plasma total antioxidant status in different diseases

The pathological increase of oxygen free radical generation has already been recognised in more than one hundred diseases. To gain information about the consequences of oxidative stress the investigation of plasma antioxidants seems to be plausible. In our study we used a new kit (RANDOX, England) for measurement of total antioxidant status (TAS) to determine whether it has diagnostic value in comparison with our earlier results of measuring other parameters of oxidative stress in the following diseases: i./In the group of patients with ischemic heart disease (n = 19) the TAS elevated from 1.08 +/- 0.13 to 1.16 +/- 0.11 mM after 2 weeks of cardioprotective drug administration showing the beneficial effect of drug treatment. ii./In the group of patients with essential hypertension (n = 47) its values were below the normal range (1.11 +/- 0.15 mM) at the time of the first investigation and increased gradually following antihypertensive treatment. iii./The changes of TAS values of patients who underwent open (n = 21) or laparoscopic (n = 21) cholecystectomy indicated the less surgical trauma following laparoscopic procedures. Our results suggest that determination of TAS is a valuable and reproducible method to detect the actual antioxidant status in patients.

The effects of bisaramil and antiarrhythmics on free radical generation of isolated neutrophil granulocytes

The aim of this study was to investigate the effect of bisaramil--an antiarrhythmic drug under clinical trials--on free radical generation of isolated polymorph neutrophil granulocytes (PMN) and to compare its activity with well-known antiarrhythmics. PMNs were isolated from healthy beagle dogs, and superoxide radical generation was induced by phorbol-myristate-acetate. Free radical generation capacity of stimulated PMNs were measured. Bisaramil exerted a concentration dependent inhibitory effect on stimulated free radical generation. At the investigated concentration range of the antiarrhythmics only propafenon, mexiletine and diltiazem showed similar activity as bisaramil, but clear concentration dependency could not be seen in any of the cases. According to the results of this study inhibition of stimulated free radical production by isolated PMNs can not be closely related merely to either membrane stabilizing or Ca-antagonistic activity of drugs. In vitro inhibitory action of bisaramil on free radical generation indicates a possible cardioprotective effect existing independently of its antiarrhythmic one. This observation may be important in outlining the range of clinical indications of bisaramil as it may also be useful in the treatment of reperfusion injury.

Bisaramil and antiarrhythmics as inhibitors of free radical generation

The aim of this study was to investigate the effect of bisaramil--an antiarrhythmic drug under clinical trials-on free radical generation of isolated polymorph neutrophil granulocytes (PMN) and furthermore to compare its activity to that of well-known antiarrhythmics which have different modes of action. PMNs were isolated from healthy beagle dogs, and superoxide radical generation was induced by phorbol-myristate-acetate. Stimulated free radical generation capacity of PMNs and the time lag necessary for the initiation of free radical production were measured. All compounds were used at the concentrations of 10, 25, 50, 75, 100 micrograms ml-1. None of the antiarrhythmics stimulated by itself the free radical generation. Bisaramil exerted concentration dependent inhibitory effect on PMA-stimulated free radical generation and prolonged the time lag concentration dependently. At the investigated concentration range of antiarrhythmics only propafenon, mexiletine and diltiazem showed similar activity to bisaramil, but clear concentration dependency could not be seen in any of the cases. According to the results of this study inhibition of the stimulated free radical production of isolated PMNs cannot be closely connected merely to either membrane stabilizing or Ca-antagonistic activity of drugs. In vitro and earlier measured in vivo inhibitory action of bisaramil on free radical generation indicate a possible cardioprotective effect existing independently from its antiarrhythmic one. This observation may be important in outlining of the clinical indication field of bisaramil, and may be useful in the treatment of reperfusional damage.

Effects of lidocaine on cerebral lipid peroxidation and neutrophil activation following complete compression ischemia

The effect of lidocaine on brain lipid peroxidation, as reflected by jugular vein malondialdehyde concentrations, and of polymorphonuclear leukocyte activation in peripheral venous blood samples following transient global cerebral ischemia, were studied. In normothermic dogs subjected to a 10 min elevation of cerebrospinal fluid pressure and a subsequent 60 min reperfusion, the malondialdehyde concentration during the first 3 min of reperfusion increased significantly (p < 0.05) in the jugular vein. Lidocaine (10 mg/kg, i.v.), administered 10 min before ischemia, not only prevented the elevation of the malondialdehyde concentrations during ischemia, but also provoked a significant transient decrease 10 min after the start of reperfusion. A 10 min ischemia and a 60 min reperfusion caused no significant changes in the polymorphonuclear leukocyte radical production, neither following ischemia nor after addition of lidocaine. These results suggest that lidocaine exerts a scavenging action on free radical processes but that it has no direct effect on the polymorphonuclear leukocyte activation in the early phase of reperfusion following ischemia.

Effect of the ultrashort-acting beta-blocker Brevibloc on free-radical-mediated injuries during the early reperfusion state

The left descending coronary artery (LAD) was ligated for 45 min or 90 min followed by 1-h reperfusion. During experiments the animals in Group I (15 dogs) received saline infusion, in Group II (20 dogs) they received the ultrashort-acting beta-blocker Brevibloc (esmolol HCl). The marker of lipid peroxidation the malondialdehyde (MDH) as well as endogen scavengers, the glutathione (GSH), and superoxide dismutase (SOD) were measured in the heart tissue homogenates. In blood and heart tissue samples the 6-keto-prostaglandin F1 alpha (PGF1 alpha) and thromboxane B2 (TXB2) were determined. Biochemical measurements revealed that esmolol HCl has beneficial effect on the free-radical-meduated-damage reducing the MDA content in the ischemic area. In Group I the value of MDA after 90 min of LAD ligature was 138 +/- 5.6%, in Group II the elevation was only 107.4 +/- 3.2%. After treatment with Brevibloc the GSH content of ischemic-reperfused areas decreased slightly (81.75 +/- 3.5% of the normal value), moreover, in Group I the depletion of GSH was considerable (64.5 +/- 4.2%). Coronary reperfusion caused the release of eicosanoids in both groups, mainly in the first 10 min. The highest value of thromboxane in blood samples could be measured in Group I after 90 min of LAD ligature (24.8 +/- 3.6 pmol/ml; the normal value 8-12 pmol/ml). In Group II during the same period of experiments the TXB2 in the blood was 14 +/- 3.7 pmol/ml. In heart tissue samples the amount of endoperoxides increased in ischemic and non-ischemic areas of Group I and II. Nevertheless, the calculated ratio of PGF1 alpha and TXB2 was near to the normal after Brevibloc treatment (0.85-0.9; the normal values were 1-1.2). These results indicate that esmolol HCl can modulate both the free-radical-mediated reaction and arachidonic acid metabolism.

Effect of Ca-antagonists, beta-blockers and antioxidant during reperfusion period

The purpose of this study was to assess the influence of the radical scavenger (MTDQ-DA), Ca-antagonist (Verapamil) and ultrashort-acting beta-blocker (Brevibloc) on arachidonic acid metabolism and free radical mediated damage. In dog experiments, the left descending coronary artery (LAD) was ligated for 45 min or 90 min followed by one hour reperfusion. Blood samples were taken at different times of occlusion and recirculation for determination of 6-keto PGF1 alpha and TXB2. At the end of the experiments heart tissue samples were excised from injured areas and from the intact part of the left ventricular muscle. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) as well as prostacyclin and thromboxane were determined in tissue samples. Free radical mediated damage (increased lipid peroxidation and exhaustion of endogenous scavengers) could be diminished significantly by antioxidant treatment and moreover, therapy of Verapamil and Brevibloc preserved reduced. It was characteristic that release of endoperoxides was present in each case but the highest values were measured in non-treated animals. Tissue content of prostacyclin and thromboxane varied in differently treated groups, however the altered ratio of PGF1 alpha and TXB2 showed strong influence of the antioxidatnt, Ca-antagonist and beta-blocker.

Free radical mediated injuries after coronary artery occlusion

The left descending coronary artery (LAD) of mongrel dogs was ligated for one month to evaluate the effect of a dihydroquinoline-type antioxidant (MTDQ-DA) during the healing process of myocardial infarction. Thirty animals were divided into three groups: I) control animals (10 dogs) were treated with saline infusion during operation and postoperative days; II) 10 dogs were treated with intravenous MTDQ-DA during the operation followed by postoperative oral treatment, and III) 10 animals were treated with preoperative and postoperative oral treatment plus intraoperative MTDQ-DA infusion. The antioxidant effects were evaluated by measurements of the lipid peroxidation and product malondialdehyde (MDA) and of endogenous scavengers: reduced glutathione (GSH) and superoxide dismutase (SOD) in the ischemic and in intact areas. Ultrathin sections were investigated by JEOL 100 C electron microscope. Elevation of lipid peroxidation (LPO) was present in each group. The most remarkable changes were seen in the control ischemic areas (152 +/- 6.7%). GSH was depleted in the infarcted areas of the control hearts (60 +/- 5.6%), in the antioxidant treated animals this thiol compound was only slightly decreased (81 +/- 5.6%). SOD activity showed a sharp decline (group I) in both ischemic (52 +/- 8.3 U/g) and non-ischemic parts of the left ventricle (78 +/- 7 U/g). After MTDQ-DA treatment (groups II, III) SOD activity diminished only in the ischemic area (83 +/- 8.5 U/g); other parts showed normal (123 +/- 7.2 U/g) activity. According to ultrastructural examinations, MTDQ-DA diminished the degree of structural injury.

Orientation dependence and motional properties of spin labels in cardiac and skeletal muscle fibres

Orientation dependence and rotational motion of maleimide spin labels attached to the fast reacting thiol sites of myosin were studied in glycerinated cardiac and skeletal muscle fibres in rigor and in relaxing medium. The probe order in skeletal muscle was shown to be about one order of magnitude higher than that in cardiac muscle. In skeletal muscle in rigor the orientational order is static on the time scale of the saturation transfer electron paramagnetic resonance measurement (ST EPR, rotational correlation time of the label is greater than 1 ms), but in cardiac muscle fibres, a disorder was observed which was at least partly dynamical, the rotational correlation time being about 100 microseconds. In relaxing solution the degree of order of probe molecules in both types of muscle was strongly reduced at and above the resting length. The disorder was at least partly dynamical on the ST EPR time scale, the apparent rotational correlation times being 200 microseconds for skeletal muscle and 60 microseconds for cardiac muscle, respectively. According to the results of ST EPR the rotational behavior of cross-bridges was identical in cardiac and skeletal muscle in relaxing medium.

Promising reduction of ventricular fibrillation in experimentally induced heart infarction by antioxidant therapy

Studies were undertaken using a synthetic free radical scavenger (MTDQ-DA) on regional ischaemic dog hearts; it was found that the rate of malignant ventricular arrhythmias and fibrillation after coronary ligature unexpectedly decreased. According to experiments on 22 dogs, the intravenous MTDQ-DA therapy decreases the unfavourable ECG consequences of left anterior descending branch ligature: already 5 to 10 minutes after drug administration the ST segment elevation, the QT interval lengthening and the occurrence of ventricular extrasystoles and salvos are diminishing. The so-called epicardial ST map ameliorates rapidly. MTDQ-DA as a blocking agent of free radicals is able to prevent the irritative stimuli around and in the border zone of an infarct, has a vigorous anti-arrhythmogenous effect and greatly reduces the electric heterogeneity. These unexpected results may lead to a promising therapy for the acute heart infarction.

Myocardial protection by antioxidant during permanent and temporary coronary occlusion in dogs

In an ischaemic heart model the lipid peroxidation, scavenger state and ultrastructure were studied, to determine the action of a new antioxidant of dihydroquinoline type (MTDQ-DA). In dog experiments, the left descending coronary artery (LAD) was ligated permanently (30 minutes, 1, 2 or 3 hours) or temporarily (30 minutes, 1 or 2 hours of ischaemia followed by 1 hour of recirculation). The experimental protocol involved two groups: control animals without antioxidant treatment and animals treated with antioxidant infusion during the ischaemic and reperfusion period. In both groups, the thiobarbituric acid reactive product, the malondialdehyde (MDA), reduced glutathione (GSH) and superoxide dismutase (SOD) were measured, to illustrate the injured or scavenged state of the membrane system. In nontreated animals the permanent and temporary LAD increased the MDA content, decreased GSH concentration (mainly during reperfusion) and reduced SOD activity. Treatment with MTDQ-DA diminishes the characteristic biochemical changes. According to ultrastructural investigations, irreversible alterations (Ca deposits in the mitochondria, disruption of intramitochondrial membranes, hypercontraction bands) occurred only in the control group. Anti-oxidant therapy is able to reduce the myocardial damages both quantitatively and qualitatively.

Effects of antioxidant therapy in experimentally induced heart infarcts

Experiments were performed on dog hearts following coronary ligation and treatment with synthetic antioxidant of dihydroquinoline type. Experimental groups were: control dogs, dogs with ligation of descendens anterior coronary branch, coronary ligated dogs with antioxidant pretreatment and dogs with coronary ligation and simultaneous antioxidant infusion therapy. The heart infarction per se is accompanied by the disintegration of membrane polyunsaturated fatty acids expressed by increase of malondialdehyde (MDA) concentration and the impairment of natural scavenging characterized by the decrease of superoxide dismutase (SOD) and reduced glutathione (GSH) content. The oral pretreatment with antioxidant for 8 days prevented or decreased the unfavourable pathobiochemical responses. The acute infusion therapy exerted no immediate protection, nonetheless, it could decrease the severity of pathological signs.

Lipid peroxidation in lung of rats exposed to hyperoxic, hypoxic and ischemic effects

Rat experiments were undertaken to describe the range of the endogenous lipid peroxidation (measured by formation of malondialdehyde [MDA] in lung tissue) and to analyze the effects of hyperoxic, hypoxic and ischemic influences. The acute hyperoxia caused a moderate increase in lipid peroxidation. The MDA formation in lungs of rats was perceptibly higher in low oxygen environment, while the highest values were found in ischemic lungs. The cytotoxic metabolites cause unfavourable influences on the lung structure (perivascular, interstitial and alveolar edema, destroyed epithelial lining with disintegration of lamellar membranes of the type II-pneumocytes). The findings suggest that potential danger of the oxygen free radicals is an increased lipid peroxidation of lung tissue causing alveolocapillary destruction and extensive exudation with pathologic dwindling of lung function.

Lipid peroxidation and scavenger mechanism in experimentally induced heart infarcts

Dog experiments were performed to describe the time course of lipid peroxidation after various ischemic influences of the heart measured by formation of malondialdehyde (MDA), and the scavenger action determined by reduced glutathione (GSH) content and superoxide dismutase (SOD) activity. Experimental groups consisted of control dogs having intact hearts and dogs with acute ramus descendens anterior ligature (LAD) having ischemic areas through 15, 30, 45 minutes and 1, 2, 3, 24 hours. Heart tissue for biochemical assays was excised from both the ischemic areas and from nonischemic left ventricle. The acute ischemia caused characteristic alterations in the biochemical parameters: MDA level gradually increased with its peak value being found at the end of 3 hours ligature. GSH levels decreased moderately, whereas SOD levels reduced sharply. As increased MDA formation indicates breakdown of the polyunsaturated fatty acids (PUFA) in the membranes and decreased GSH and SOD levels indicate impairment of the natural scavengering, the observed changes clearly outline the extent of disintegration of membrane structure and function.

Epicardial ECG signals following global myocardial ischaemia

Experiments were performed on 10 dog hearts undergone 15 to 90-minute normothermic arrests and 60-minute reperfusion in a special heart-lung model. The purpose of the experiments was to characterize the global ischaemic effects recorded on epicardial electrograms. The duration of QRS complexes and of RR intervals, the integral of ST segment shifts (sigma ST), the number of points showed ST segment displacements (NoST) and the ST segment isopotential map obtained by computer control were evaluated. Only a minor ST segment deviation, a small increase in duration of QRS complexes and of RR intervals with bradycardia and a tendency to electrical stability were found after global ischaemic influences. These observations indicate that pathological electrical manifestations occurring after a global ischaemia are less serious than those occurring after a focal ischaemia.

Ultrastructural changes of the subendocardium in ischemic and cardioplegic states before and after reperfusion

Unprotected and preserved myocardial ultrastructures were analyzed in prepump and postreperfused states. The experiments were divided into three groups: group 1 - normal hearts functioning 60 min in a special heart-lung model; group 2 - hearts with 30, 60, 90 and 120 min of normothermic ischemia plus 60 min of recirculation; group 3 - hearts with 30, 60, 90 and 120 min of hypothermic cardioplegia plus 60 min of recirculation. Anoxic hearts could be set in motion, but after longer anoxia the symptoms of stone-heart regularly appeared. Reperfusion induced grave ultrastructural changes both in the energy system (mitochondrial edema, rupture and lysis of cristae) and myofibrils (hypercontraction, elongation, Z line anomalies). Cardioplegic hearts showed a dynamic recovery. However, after reperfusion, characteristic sporadic signs of ischemia could always be demonstrated.

Ultrastructural features of canine kidneys after preservation with hyperthermic solutions and subsequent reperfusion

An analysis of the ultrastructural features of 35 canine kidneys after hypothermic preservation in Rheomacrodex, Collins3 and Sacks II solutions, and subsequent autologous reperfusion for 2 to 3 hours is presented. Signs of irreversibility (intramitochondrial crista fragmentation, cell membrane rupture, detachment of the brush borders in the area of the proximal tubular system) were confined to the Rheomacrodex-preserved kidneys. Other abnormal features (cytoplasmic vacuolation, mitochondrial swelling in the proximal tubules, vacuolation of the visceral epithelial cells, heteromorphism in the glomerular system) found in the acute stage of revascularization may be regarded as reversible and account for the transitory functional disorders of renal transplants.

[Value of organ preservation with Collins-3 and Sacks II solutions of warm ischemic and re-perfused kidneys]

The protective effect of Collins or Sacks solutions was reduced after warm ischemia in preserved and reperfused dog kidneys. The degree of the developed pathologic alterations was connected with the length of the warm ischemic period. Functional changes as decrease of microcirculation and proteinuria and structural sequences as edema and diverse disintegration in glomeruli and tubuli were produced.

Description and interpretation of morphological changes in canine kidneys after preservation with hypothermic solutions and subsequent reperfusion

The morphological appearance of canine kidneys preserved with hypothermic solutions of three different types (Rheomacrodex, Collins 3 and Sacks-II) was studied in acute autologous reperfusion models. While at the end of preservation the renal structure still seemed intact (with the exception of the Rheomacrodex model), reperfusion was associated with the manifestation of hitherto latent structural lesions. This is confirmed by light-microscopic features (hydropic swelling and destruction of the tubular epithelium), enzyme histochemical studies (positive alkaline phosphatase reaction of the Bowman space) and topo-optical reactions (loss of anisotropy of the cytomembranes in the presence of fairly well preserved birefringence of the basement membranes).

Study of factors affecting the antigen structure of the donor kidney. I. Interpretation of the relationship between periodate pretreatment and the rejection phenomena of canine kidney allografts

Donor kidneys were preserved in a Collins-4 solution containing periodate in concentrations of 10(-2) and 10(-4) mole/l, respectively, in an attempt to oxidize the carbohydrate components of the antigen-carrying membrane surfaces and thus to influence the rejection phenomena exhibited by the allogeneic kidney. All kidneys were, however, rejected as a result of a hyperacute reaction indicating that periodate did not react with the hydrophobic membrane structures in vivo. Not only did the antigen thus remain unchanged but the vulnerability of other renal structures to the destructive effect of the killer cells also increased as a result of toxic damage.

The aminogram of the urine produced by the preserved kidney

The function of autogenous canine kidneys may be considered even after successful preservation and reperfusion to be pathological for about 3 to 4 days, since a condition characterized by proteinuria and increased amino aciduria exists for a while.

Description and interpretation of functional changes in canine kidneys after preservation with hypothermic perfusates and subsequent reperfusion

The function of canine kidneys stored with hypothermic solutions (Rheomacrodex, Collins4, Sacks) was studied in acute autologous reperfusion models. Changes in the perfusates (increase in LDH level and minor increase in K+ level), as well as the quantitative and qualitative properties (proteinuria) of the urine produced by the graft may be ascribed to storage and revascularization which affect the cells and their membranes. The alterations of the circulatory parameters demonstrable at the outset and during revascularization are due to an increase in renovascular resistance of hypothermic origin on the one hand, and to acute tubular epithelial damage inherent in the procedure, on the other.

Description and interpretation of structural changes in canine kidneys after preservation with a hyperosmolar solution and reperfusion

The effects of hypothermic preservation of canine kidneys for 24 hours by the use of the Sacks solution, and additional autogenous reperfusion were studied by means of submicroscopic morphological methods. While preservation with the Sacks solution was to ensure normal organization of the lipoprotein structures of the basement and cell membranes, in case of additional reperfusion, even of short duration, a substantial or complete loss of anisotropy of the cytomembranes was demonstrable. The present report is the first to be published in the literature on polarization microscopic studies concerned with the effects of kidney preservation and of reperfusion.

Characteristics of hyperacute rejection of swine kidney xenografts perfused with canine blood

Twenty-five swine kidney xenografts previously flushed with Collins-4 solution were perfused with canine blood and the functional and morphological changes resulting from xenoperfusion were studied. Blood flow of the kidneys practically ceased by the end of 8 minutes parallel with progressive swelling and cyanosis of the organ. Microscopic study of the kidneys revealed gross destruction of the glomerular and tubular apparatus, marked by extensive oedema, interstitial haemorrhages, diffuse capillary thrombosis and damage to the cell membrane.