Effects of PACAP and preconditioning against ischemia/reperfusion-induced cardiomyocyte apoptosis in vitro

The neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) and its receptors are widely expressed in the nervous system and various other tissues. PACAP exerts strong anti-apoptotic effects in neuronal cell lines and, according to recent data, also in non-neuronal cells. The peptide is present in the cardiovascular system and has various distinct effects. We have demonstrated earlier that PACAP has protective effects against in vitro ischemia/reperfusion-induced apoptosis in cardiomyocytes. Preconditioning with brief intermittent periods of ischemia is known to provide protection against ischemic injury. The aim of the present study was to investigate whether PACAP could enhance the protective effect of preconditioning against in vitro ischemic injury. Cultured cardiomyocytes were exposed to brief preconditioning ischemia followed by 2 h ischemia and 4 h reperfusion. Both PACAP treatment and preconditioning alone significantly increased cell viability and decreased the ratio of cell death. Pretreatment with PACAP was found to further reduce the level of cleaved caspase-8 but it did not lead to additional survival rate when compared to cells treated with PACAP or preconditioning alone. These results show that although both PACAP and preconditioning have a protective effect against ischemia/reperfusion-induced cardiomyocyte apoptosis, their effects are not additive.

Pathology and diagnostic options of lower limb compartment syndrome

BACKGROUND

The indication of surgical treatment in lower limb compartment syndrome mostly depends on the clinical signs which can be often uncertain, resulting in delayed insufficient intervention.

AIM

The aim of the study was to evaluate the progression of compartment syndrome by measuring of intracompartmental pressure and monitoring of decreased tissular oxygenation, indicating an insufficient secondary microcirculation.

MATERIALS AND METHODS

16 patients were examined in our study (12 males, 4 females, mean age: 62.7+/-9.5 years), who underwent acute lower limb revascularization surgery for a critical (lasting more than 4 hours) limb ischemia. The indications were: 5 iliac artery embolizations and 11 femoral artery occlusions. After revascularization, on the second postoperative day, we detected significant lower limb edema and swelling of several grade. To monitor the elevated intracompartmental pressure (ICP) and to evaluate the extremital circulation, we used KODIAG pressure meter and the tissular oxygen saturation (StO2) was measured by near-infrared-spectroscopy.

RESULTS

In 12 cases the ICP exceeded the critical 40 mmHg. In these patients the average StO2 was 50-53%, in spite of complete recanalization. In these cases we made urgent, semi-open fasciotomy. In 4 cases, where the clinical aspect showed compartment syndrome, the measured parameters did not indicate a surgical intervention (ICP: 25-35 mmHg, StO2: around normal).

SUMMARY

A novel approach in our examination is that, besides empirical therapeutic guidelines generally applied in clinical practice, we established an objective, parameter-based ("evidence based medicine") surgical indication strategy for the lower limb compartment syndrome. Our parameter results produced by the above pressure and saturation measurements help the clinicians to decide between conservative and operative treatment of the disease.

Alanyl-glutamine infusions to patients with acute pancreatitis

In this study we infused different amounts of glutamyl-dipeptides (group 1: 1.5 g ALA-GLN + 3.5 g GLY-GLN, group 2: 20 g ALA-GLN, group 3: 40 g ALA-GLN) for a period of five days into patients with acute pancreatitis. In spite of this high amount of ALA-GLN administration we were not able to normalise the depleted glutamine pool of skeletal muscle in these catabolic patients.

Serum phenylalanine in patients post trauma and with sepsis correlate to neopterin concentrations

Increased blood concentrations of phenylalanine in patients with trauma and sepsis are common but unexplained. We examined the potential relationship between serum concentrations of phenylalanine and the immune activation marker neopterin in 84 specimens of 18 patients (14 males and 4 females) post-trauma during 12-14 days of follow up. Compared to healthy controls, average phenylalanine and neopterin concentrations were elevated in patients, and there existed a positive correlation between concentrations of the two analytes (r (s) = 0.375, p < 0.001). No such association existed between neopterin and tyrosine concentrations (r (s) = -0.018), but neopterin concentrations correlated to the phenylalanine to tyrosine ratio (r (s) = 0.328, p = 0.001). Increased phenylalanine implies insufficient conversion by phenylalanine (4)-hydroxylase (PAH). Oxidative stress due to immune activation and inflammation may destroy cofactor 5,6,7,8-tetrahydrobiopterin and impair PAH activity. This assumption is further supported by the correlation found between higher neopterin concentrations and higher phenylalanine to tyrosine ratio, which estimates efficacy of PAH.

Short-term effects of N-acetylcysteine and ischemic preconditioning in a canine model of hepatic ischemia-reperfusion injury

AIMS

We evaluated the possibility that repeated ischemic preconditioning or N-acetylcysteine (NAC) could prevent ischemia-reperfusion injury as determined by indocyanine green plasma disappearance rate (ICG-PDR) or has favorable hemodynamic effects during reperfusion in an in vivo canine liver model.

METHODS

Under general anesthesia, 3 groups of mongrel dogs (n = 5 per group) were subjected to (1) 60-min hepatic ischemia, (2) same ischemia preceded by intravenous administration of 150 mg kg(-1) NAC, and (3) three episodes of IPC (10-min ischemia followed by 10-min reperfusion) prior to same ischemia. Hepatic reperfusion was maintained for a further 180 min, with hemodynamic and hepatic function parameters monitored throughout.

RESULTS

Plasma disappearance rate of indocyanine green and serum levels of aspartate transferase and alanine transferase showed no significant differences between groups. Although liver injury was obvious, reflected by hemodynamic, blood gas, and liver function tests, NAC and IPC failed to prevent decay in hepatic function in this canine model.

CONCLUSION

The results do not support the hypothesis that short-term use of NAC and IPC is beneficial in hepatic surgery.

Reperfusion injury and inflammatory responses following acute lower limb revascularization surgery

After revascularization of an acute arterial occlusion the development of a serious ischaemic-reperfusion injury is a menacing challenge and a hard task in peripheral vascular surgery. A whale of evidences point to oxidative stress, as an important trigger, in the complex chain of events leading to reperfusion injury. In the present study authors aimed to examine oxidative stress parameters, antioxidant-prooxidant state and leukocyte adhesion molecules (CD11a and CD18) expression following acute revascularization surgery of lower limb.10 patients were examined in the prospective randomized study. Peripheral blood sample was collected in ischaemic period, and after reperfusion in the 2nd and 24th hours, and on 7th day. Superoxide-dismutase activity, reduced glutathion concentration and leukocytes free radical production were measured. The degree of lipidperoxidation was marked with the quantity of malondialdehyde. The expressions of adhesion molecules were measured with flowcytometry.The speed and rate of free radical production significantly increased in the early reperfusion (p<0.05). The level of antioxidant enzymes decreased after revascularization. The CD11a and CD18 expression of the granulocytes significantly (p<0.05) decreased right after the revascularization, but with a gradual elevation until the 7th day they exceed the ischaemic value. Our results showed a time specific turnover of the sensitive antioxidant-prooxidant balance after revascularization operation.

Ischaemic postconditioning reduces peroxide formation, cytokine expression and leukocyte activation in reperfusion injury after abdominal aortic surgery in rat model

OBJECTIVE

We studied the protective effects of ischaemic postconditioning (PS) on ischemia-reperfusion injury of the lower extremities in a rat model of abdominal aortic intervention. We aimed to examine the evoked oxidative stress, cytokine expression and leukocyte activation after revascularisation surgery.

METHODS

Anesthetized animals (48 Whistar rats) underwent a 60 min infrarenal aorta cross-clamping. After the ischaemic period, an intermittent 4 times 15 s reperfusion--15 seconds ischaemic episodes--were applied (ischaemic postconditioning: group PS). Then we started a 120 min reperfusion in the aorta. In untreated group animals underwent a long ischaemia (60 min) and the following reperfusion (group IR). Peripherial blood samples were collected before operation, and in early (5, 10, 15, 30, 60 and 120 min) reperfusion periods. Serum peroxide level, TNF-alpha concentration, myeloperoxidase (MPO) activity and PMA-induced leukocyte ROS production were measured.

RESULTS

In PS group, plasma peroxide level elevation was significantly lower in very early reperfusion (5-30 min) comparing to non-conditioned IR group (10.04+/-1.9 microM/l vs. 16.91+/-3.67 microM/l, p<0.05). PS also reduced serum TNF-alpha concentration (167.41+/-31.26 microg/ml vs. 116.55+/-12.04 microg/ml, p<0.05), MPO activity (1.759+/-0.239 microM/ml vs. 1.22+/-0.126 microM/ml, p<0.05) and leukocyte activation detected by PMA-induced leukocyte ROS production (5.7+/-0.96 AU/10(3) cells vs. 4.63+/-0.69 AU/10(3) cells).

CONCLUSIONS

Ischaemic postconditioning could reduce ROI production after IR in early reperfusion period, thus limiting ROI mediated tissue lesion, cytokine-leukocyte activation and inflammatory responses. PS seems to be an effective tool in vascular surgery to reduce reperfusion injuries after revascularization interventions.

Effects of fructose-1,6-diphosphate on endo- and myocardial purine metabolism during coronary artery bypass grafting surgery

AIM

During ischemia, the glycolytic pathway is up-regulated to anaerobically produce adenosine triphosphate (ATP). However, this is short-lived, due to negative feedback on phosphofructokinase from accumulating lactate. Since fructose-1,6-diphosphate (FDP) enters glycolysis distal to this inhibitory site, exogenously administered FDP may yield ATP-independent lactate accumulation and thus ameliorate ischemic injury. The aim of this prospective randomized study was to investigate whether the improved myocardial preservation by FDP could be attributed to improved intermediary metabolism in patients who underwent coronary artery bypass grafting surgery (CABG).

METHODS

Thirty-eight patients scheduled for elective CABG were studied. During operation, aortic and coronary sinus blood were collected at different timepoints and analysed by chromatography. Ten patients received 250 mg/kg FDP and 10 received 5% dextrose (control) as intravenous pretreatment prior to cardiopulmonary bypass. In the second stage, 9 patients received 2.5 mM (1.4 g/L) FDP and 9 patients 5% dextrose with the cardioplegic solution. Myocardial metabolism was quantified by measuring nucleotide catabolites including inosine and hypoxanthine.

RESULTS

The release of inosine-hypoxantine was increased in both the FDP and the control groups; however, compared to baseline, inosine-hypoxantine levels were significantly elevated at 0, 1, 5 and 10 minutes following reperfusion in the control group. This was in contrast to the earlier recovery to baseline levels (after 5 minutes following reperfusion) in the FDP group.

CONCLUSION

These data suggest that FDP may contribute to myocardial cytoprotection during cardiopulmonary bypass. Moreover, myocardial nucleotide metabolite levels showed no evidence for a protective effect of FDP on nucleotide degradation between the treated and the control groups.

PKA-Bad-14-3-3 and Akt-Bad-14-3-3 signaling pathways are involved in the protective effects of PACAP against ischemia/reperfusion-induced cardiomyocyte apoptosis

The neuropeptide PACAP (pituitary adenylate cyclase activating polypeptide) and its receptors are widely expressed in the nervous system and various other tissues. PACAP has well-known anti-apoptotic effects in neuronal cell lines. Recent data suggest that PACAP exerts anti-apoptotic effects also in non-neuronal cells. The peptide is present in the cardiovascular system, and has various distinct effects. The aim of the present study was to investigate whether PACAP is protective against in vitro ischemia/reperfusion-induced apoptosis in cardiomyocytes. Cultured cardiomyocytes were exposed to 60 min ischemia followed by 120 min reperfusion. The addition of PACAP1-38 significantly increased cell viability and decreased the ratio of apoptotic cells as measured by MTT test and flow cytometry. PACAP induced the phosphorylation of Akt and protein kinase A. In the present study we also examined the possible involvement of Akt- and protein kinase A-induced phosphorylation and thus inactivation of Bad, a pro-apoptotic member of the Bcl-2 family. It was found that ischemia significantly decreased the levels of phosphorylated Bad, which was counteracted by PACAP. Furthermore, PACAP increased the levels of Bcl-xL and 14-3-3 protein, both of which promote cell survival, and decreased the apoptosis executor caspase-3 cleavage. All effects of PACAP1-38 were inhibited by the PACAP antagonist PACAP6-38. In summary, our results show that PACAP has protective effects against ischemia/reperfusion-induced cardiomyocyte apoptosis and provides new insights into the signaling mechanisms involved in the PACAP-mediated anti-apoptotic effects.

Protective effects of pituitary adenylate cyclase activating polypeptide in endothelial cells against oxidative stress-induced apoptosis

Pituitary adenylate cyclase activating polypeptide (PACAP) is a widely distributed neuropeptide that has various different functions in the nervous system and in non-neural tissues. Little is known about the effects of PACAP in endothelial cells. The aim of the present study was to investigate the effects of PACAP on endothelial cell survival and apoptotic signaling pathways under oxidative stress. Mouse hemangioendothelioma (EOMA) cells were exposed to 0.5mM H(2)O(2) which resulted in a marked reduction of cell viability and a parallel increase of apoptotic cells assessed by MTT test and flow cytometry. Co-incubation with 20nM PACAP1-38 increased cell viability and reduced the percentage of apoptotic cells. Flow cytometry analysis showed that oxidative stress reduced the phosphorylation of the anti-apoptotic ERK and increased the phosphorylation of the pro-apoptotic JNK and p38 MAP kinases. PACAP1-38 treatment ameliorated these changes: levels of phospho-ERK were elevated and those of phospho-JNK and p38 were decreased. All these effects were abolished by simultaneous treatment with the PACAP antagonist PACAP6-38. In summary, our results show that PACAP effectively protects endothelial cells against the apoptosis-inducing effects of oxidative stress.

Fetal electrocardiogram ST-segment analysis and prediction of neonatal acidosis

OBJECTIVE

To determine the diagnostic value of fetal ST-segment analysis (STAN) in predicting neonatal acidosis.

METHODS

The STAN S21 was used to monitor singleton fetuses in labor with abnormal FHR. Physicians later reviewed tracings to identify any ST events dictating intervention. Outcome measures were umbilical artery pH< or =7.15 and pH< or =7.05 at birth. The sensitivity, specificity, PPV, and NPV of a significant ST event to predict both outcomes were calculated.

RESULTS

Analysis included 411 women. Sensitivity of a significant ST event for screening pH< or =7.15 (21.9%) was 38% (41/108), specificity 83% (252/303), PPV 45% (41/92) and NPV 79% (252/319), and for pH< or =7.05, it was (3.4%), 62.5% (10/16), 79% (313/395), 11% (10/92), and 98% (313/319), respectively.

CONCLUSION

In a population with abnormal FHR in labor, STAN sensitivity is moderate (almost 40%) for predicting pH< or =7.15 and better (almost 60%) for more severe acidosis (pH< or =7.05).

Effect of cardiopulmonary bypass on cytokine network and myocardial cytokine production

BACKGROUND

In addition to the well-investigated proinflammatory cytokine expression, there is an ever increasing interest in the field of anti-inflammatory response to cardiopulmonary bypass (CPB). Evidence suggests that myocardium serves as an important source of cytokines during reperfusion and application of CPB. The effect of coronary artery bypass graft (CABG) without CPB on myocardial cytokine production has not as yet been investigated.

HYPOTHESIS

Cardiopulmonary bypass can cause long-term disturbance in pro- and anti-inflammatory cytokine balance, which may impede a patient's recovery following surgery. Therefore, the effect of CPB on the balance of the pro-/anti-inflammatory cytokines network and myocardial cytokine outflow was assessed throughout a longer period after surgery.

METHODS

Twenty patients were scheduled for CABG with CPB and 10 had off-pump surgery. Blood samples were taken before, during, and over the first week following surgery. Coronary sinus blood samples were collected during surgery. The ratio of pro- and anti-inflammatory cytokines was calculated and the cytokine concentration of peripheral and coronary sinus blood were compared in both groups.

RESULTS

Pro-/anti-inflammatory cytokine ratio decreased early after CPB followed by a delayed and marked increase. A more balanced ratio was present following off-pump surgery. Coronary sinus levels of certain cytokines exceeded the concentration of systemic blood in the course of CPB but not during off-pump operation.

CONCLUSION

Patients show pro-inflammatory predominant cytokine balance at a later stage after CPB in contrast to those without CPB. The heart produces a remarkable amount of cytokines only in the course of surgery with CPB.

Evolvable work-centred support systems for command and control: creating systems users can adapt to meet changing demands

Military command and control (C2) organizations are complex socio-technical systems which must constantly adapt to meet changing operational requirements. We describe our experiences in developing a work-centred support system (WCSS) to aid weather forecasting and monitoring in a military airlift C2 organization as an illustrative case. As part of the development process we conducted field observations both before and after introduction of the WCSS in their operations centre. A striking finding was the constant changes that operations personnel faced (changes in goals and priorities, changes in scale of operations, changes in team roles and structure, and changes in information sources and systems). We describe the changes in workplace demands that we observed and the modifications we needed to make to the WCSS in response. For today's fielded systems, it is seldom possible to make changes that are responsive to users' changing requirements in a timely manner. We argue for the need to incorporate facilities that enable users to adapt their systems to the changing requirements of work and point to some promising directions towards evolvable work-centred support systems.

Study of Benzylperoxy Radical Using Laser Photolysis: Ultraviolet Spectrum, Self-Reaction, and Reaction with HO2 Kinetics

The ultraviolet absorption spectrum of benzylperoxy radical and the kinetics of the reactions 2C(6)H(5)CH(2)O(2) --> products (I) and C(6)H(5)CH(2)O(2) + HO(2) --> products (II) are studied. Experiments are carried out using the laser photolysis technique with time-resolved UV-visible absorption spectroscopy over the temperature range 298-353 K and the pressure range 50-200 Torr. The UV spectrum is determined relative to the known cross section of the ethylperoxy radical C(2)H(5)O(2) at 250 nm. Using factor analysis, the spectrum obtained is refined and the concentrations of the main absorbing species are extracted. The kinetic parameters are determined by analyzing and simulating the temporal profiles of the species concentrations and the experimental optical densities in the spectral region 220-280 nm. These are obtained using the recent UV spectra of the absorbing species existing in our mechanism. The Arrhenius expressions for reactions I and II are (cm(3).molecule(-1).s(-1)) k(I) = 2.50 x 10(-14)e(1562/)(T) and k(II) = 5.70 x 10(-14)e(1649/)(T). Our results are discussed and compared to literature data.

Pituitary adenylate cyclase activating polypeptide protects cardiomyocytes against oxidative stress-induced apoptosis

Pituitary adenylate cyclase activating polypeptide (PACAP) has well-known neuroprotective effects, and one of the main factors leading to neuroprotection seems to be its anti-apoptotic effects. The peptide and its receptors are present also in the heart, but whether PACAP can be protective in cardiomyocytes, is not known. Therefore, the aim of the present study was to investigate the effects of PACAP on oxidative stress-induced apoptosis in cardiomyocytes. Our results show that PACAP increased cell viability by attenuating H2O2-induced apoptosis in a cardiac myocyte culture. PACAP also decreased caspase-3 activity and increased the expression of the anti-apoptotic markers Bcl-2 and phospho-Bad. These effects of PACAP were counteracted by the PACAP antagonist PACAP6-38. In summary, our results show that PACAP is able to attenuate oxidative stress-induced cardiomyocyte apoptosis.

Expression of CD97 and Adhesion Molecules on Circulating Leukocytes in Patients Undergoing Coronary Artery Bypass Surgery

OBJECTIVE

Leukocyte activation is thought to be responsible for the adverse effects and postoperative complications following cardiopulmonary bypass (CPB). A novel cell surface molecule, CD97, is a sensitive marker of leukocyte and primary lymphocyte activation. The present study aimed to determine the activation of different leukocyte subsets by comparing the expression of CD97 and adhesion molecules (CD11, CD18) in patients receiving coronary surgery with or without CPB.

METHODS

30 patients were enrolled and scheduled for coronary bypass surgery under CPB (20 patients, group A) and with off-pump (OP) operation (10 patients, group B). Blood samples were taken before and during surgery, and over the following first week.

RESULTS

Here, we report an early decrease in CD97 expression of granulocytes (PMN) and monocytes (MC) followed by an intensive increase reaching the maximum on postoperative days 2 and 3 in patients operated with CPB. The rate of active CD97-positive lymphocytes showed a marked, gradual increase until postoperative day 3 and remained elevated up to day 7 after CPB. OP surgery resulted in moderate alteration in the presence of CD97 on PMN, MC and lymphocytes. The expression of adhesion molecules was similar to CD97 in all leukocyte subsets.

CONCLUSION

The findings about CD97 expression suggest considerable leukocyte activation following coronary bypass with CPB compared to OP surgery. The collected data show that the lymphocytes are highly activated and involved in leukocyte sequestration after CPB. Moreover, the importance of CD97 in CPB-related inflammatory response can be stated.