Carotid artery stenting in clinical practice

BACKGROUND

Carotid artery stenting (CAS) for symptomatic and asymptomatic carotid stenosis seems to be on the doorstep of more widespread use. However, its feasibility and safety in clinical practice at a broad spectrum of hospitals needs to be determined.

METHODS

We analyzed data of the prospective multi-centre Carotid Artery Stenting (CAS) Registry of the German Arbeitsgemeinschaft Leitende Kardiologische Krankenhausarzte (ALKK).

RESULTS

From 7/1996 to 5/2004 1888 patients from 28 hospitals were included in the CAS Registry. The median hospital stay from CAS until hospital discharge was 3 days (quartiles: 2-6 days). Median patients age was 70 years (quartiles: 64-76 years) with 72.1% males. CAS for symptomatic stenosis was performed in 55% of cases. Patients treated with CAS suffered from coronary artery disease in 66.5%, had arterial hypertension in 91.7%, hyperlipidemia in 86.3% and 34.2% were diabetics. The intended CAS procedure was completed in 98.1% of cases. A stent was implanted in 97.3% of completed cases. The median intervention time was 43 min (quartiles: 30-60 min). During the hospital stay death rate was 0.3% (5/1888) and the rate of ipsilateral stroke 3.2% (58/1840). A contralateral ischemic event occurred in 1.4% (26/ 1840) of patients. The combined rate of all death or strokes was 3.8% (70/1841). Between 1996 and 2004 there was a steady increase in the use of protection devices during CAS (0% in 1996 and 97.9% in 2004; p for trend <0.0001). There was also an increase in the proportion of patients treated for asymptomatic stenoses (p for trend <0.0001). We observed a decrease of the combined endpoint of death or stroke from 6.3% in 1996 to 1.9% in 2004 (p for trend=0.021).

CONCLUSION

The multi-centre ALKK CAS Registry data confirm the feasibility and shot-term safety of CAS even in daily clinical practice. There was a rapid penetration of the use of embolic protection devices, an increase in treatment of asymptomatic carotid stenoses and a decrease in acute complication rates from 1996 to 2004.

Dynamism of NF-κB and AP-1 Activation in the Signal Transduction of Ischaemic Myocardial Preconditioning

Nuclear factor (NF)-kappaB and activation protein (AP)-1 transcription factors play an important role in the signal transduction of delayed ischaemic preconditioning (PC) leading to myocardial cytoprotection. Because the exact mechanism of the activation of these factors is still not clear, we aimed to monitor the time fluctuation of NF-kappaB and AP-1 induction in an in vivo animal model. Furthermore, we measured the induction rate of these factors using repeated cycles of PC. Following median thoracotomy, anaesthetized animals (24 New Zealand White rabbits) were subjected to ischaemic PC by occlusion of the left anterior descending coronary artery for 5 min. After 10 and 30 min, and 1, 2, 3 and 4 h of reperfusion, tissue samples were taken from the ischaemic myocardium, and the DNA binding activity of the transcription factors was measured with electrophoretic mobility shift assay. A further 12 animals were subjected to 2 x, 3 x or 4 x 5-min ischaemic PC, and after a 30-min or 1-hour reperfusion period, we investigated the possible modulation of NF-kappaB and AP-1 induction. Our results show significant, biphasically increased NF-kappaB activity with peak levels at 30 min and 3 h of reperfusion in preconditioned myocardium. AP-1 increased monophasically, with the peak level at 1 h of reperfusion. Repeated PC stimuli enhanced the activity of both transcription factors analyzed, but there was no significant correlation between the number of cycles and the rate of activation. Our results show that the activation of NF-kappaB and AP-1 have a specific time curve, and the induction of these factors is only slightly influenced by the number of PC cycles.

Comparison of HTK- and UW-solution for liver preservation tested in an orthotopic liver transplantation model in the pig

The aim of this experimental study was to compare the preservation potency of University of Wisconsin (UW) and HTK (Bretschneider) solutions in an orthotopic liver transplantation (OLT) model in pigs. Livers were harvested using an in situ perfusion technique, where organs were flushed with the solution being tested, stored on ice--cold storage (CS)--for 2 or 24 h and then transplanted. Parameters monitored were liver enzymes in serum, hepatic water content, high energy phosphates, nuclear magnetic resonance (NMR) relaxation time T2, light microscopy and bile production. CS for 24 h is an extreme in pig liver preservation and is not compatible with animal survival. Biopsies showed drastic morphological changes and grafts did not produce bile in either group. (Bile production 2 h CS: HTK, 5.6 +/- 1.8 ml/h; UW, 4.7 +/- 2.3 ml/h) Enzyme release after reperfusion (deltaSGOT, deltaLDH) was higher in long-term preservation. Hepatic tissue water content significantly decreased during CS in UW preserved livers. Edema alter reperfusion (deltaH2O: HTK 24 h = +5.6%, UW 24 h = +4.8%) and regeneration capacity after reperfusion (UW 2 h = 63%, HTK 2 h = 55%, UW 24 h = 30%, HTK 24 h = 30%) were not significantly different. However, we did not observe major differences in preservation potency between the solutions tested. Differences were correlated, rather, with length 9 time of CS, than with the solution used. Therefore, HTK solution seemed to be a low potassium containing alternative to UW solution.

Effect of single and combined supply of glutamine, glycine, N-acetylcysteine, and R,S-α-lipoic acid on glutathione content of myelomonocytic cells

BACKGROUND & AIMS

Several diseases are characterised by decreased glutathione (GSH) levels due to an enhanced formation of oxygen radicals. To increase GSH levels, the additional supply of GSH precursors was suggested. In this study we evaluated the potency of a single and combined administration of the GSH modulating substances glutamine (GLN), N-acetylcysteine (NAC), and glycine (GLY) as well as R,S-alpha-lipoic acid (LA) to enhance intracellular GSH content in a well-defined model system.

RESULTS

Exposure of myelomonocytic U937 cells for 24 h to GLN revealed a 1.5-fold enhancement of GSH levels with a concomitant decrease in the formation of reactive oxygen species and lipid peroxidation. Addition of NAC stimulated GSH formation only at subphysiological GLN levels. GLY enhanced GSH levels under GLN starvation, but caused a diminution of GSH content under optimal GLN supply. LA in combination with 2 mmol/l GLN evoked a 3.6-fold enhancement of GSH content compared to GLN starved cells.

CONCLUSION

These results demonstrate that the GSH content of U937 cells is dependent on the supply of GLN, NAC, LA, and GLY. Combinations of the single substances can enhance but also decrease the intracellular GSH content, which is of clinical importance when supplying GSH-modulating substances to patients.

Direct and indirect effects of amino acids on hepatic glucose metabolism in humans

AIM/HYPOTHESIS

The study was designed to examine the contribution of direct (substrate-mediated) and indirect (hormone-mediated) effects of amino acids on hepatic glucose metabolism in healthy men.

METHODS

The protocols were: (i) CON+S (n=7): control conditions with somatostatin to inhibit endogenous hormone release resulting in fasting plasma concentrations of amino acids, insulin (approximately 28 pmol/l) and glucagon (approximately 65 ng/l), (ii) AA+S ( n=7): amino acid infusion-fasting insulinaemia-fasting glucagonaemia, (iii) GLUC+S ( n=6): fasting amino acids-fasting insulinaemia-hyperglucagonaemia (approximately 99 ng/l) and (iv) AA-S (n=5): amino acid infusion without somatostatin resulting in amino acid-induced hyperinsulinaemia (approximately 61 pmol/l)-hyperglucagonaemia (approximately 147 ng/l). Net glycogenolysis was calculated from liver glycogen concentrations using (13)C nuclear magnetic resonance spectroscopy. Total gluconeogenesis (GNG) was calculated by subtracting net glycogenolysis from endogenous glucose production (EGP) which was measured with [6,6-(2)H(2)]glucose. Net GNG was assessed with the (2)H(2)O method.

RESULTS

During AA+S and GLUC+S, plasma glucose increased by about 50% (p<0.01) due to a comparable rise in EGP. This was associated with a 53-% (p<0.05) and a 65% increase (p<0.01) of total and net GNG during AA+S, whereas net glycogenolysis rose by 70% (p<0.001) during GLUC+S. During AA-S, plasma glucose remained unchanged despite nearly-doubled (p<0.01) total GNG.

CONCLUSION/INTERPRETATION

Conditions of postprandial amino acid elevation stimulate secretion of insulin and glucagon without affecting glycaemia despite markedly increased gluconeogenesis. Impaired insulin secretion unmasks the direct gluconeogenic effect of amino acids and increases plasma glucose.

Influence of intravenous vitamin E supplementation in cardiac surgery on oxidative stress: a double-blinded, randomized, controlled study

BACKGROUND

I.V. infusions of vitamin E emulsion (all-rac-alpha-tocopherol) may reduce ischaemia-reperfusion injury after elective cardiac surgery.

METHODS

Forty patients participated in a prospective, double-blind, placebo-controlled, randomized trial, receiving either placebo or four doses (270 mg each) of all-rac-alpha-tocopherol between 16 h before and 48 h after surgery. We determined plasma concentrations of vitamin E, vitamin C, malondialdehyde, creatine kinase, troponin I and interleukin 6 and other measures of clinical outcome.

RESULTS

Infusion of vitamin E caused normalization of vitamin E plasma concentrations during and after surgery, but had no effect on the early increase in malondialdehyde concentration or the decreases in antioxidative capacity and the water-soluble antioxidant vitamin C.

CONCLUSIONS

Normalization of plasma vitamin E concentrations with parenteral vitamin E emulsion does not affect biochemical markers of myocardial injury and does not affect clinical outcome after cardiac surgery.

Follow-up of hemorheological parameters and platelet aggregation in patients with acute coronary syndromes

Pathologic hemorheological parameters and increased platelet aggregation in association with other risk factors significantly increase the possibility of the development of myocardial ischemia. Hemorheological parameters and platelet aggregation were investigated in 157 patients (mean age: 65+/-12 years) with acute coronary syndromes and in 68 healthy subjects (mean age: 36+/-6 years). Plasma fibrinogen, plasma and whole blood viscosity, red blood cell aggregation and filterability and platelet aggregation were measured in the hospital phase (after admission, on 2nd and 6th days) and monitored after discharge (at 1, 6 and 12 months). After admission all these parameters were significantly higher in patients than in control subjects (p<0.01) and almost all of them remained in the pathologic range at discharge. Some of the rheologic parameters showed a slight improvement after 1 month, but hematocrit and whole blood viscosity were higher than those after admission and of control subjects (p<0.05). After 6 and 12 months these parameters showed a small, but significant increase. Pathologically altered hemorheological parameters could be observed in patients with classical cardiovascular risk factors and significant improvement was found after elimination of them. Antiplatelet therapy was efficient in about half of the treated patients after admission; and despite a significant improvement, the proportion of ineffectively treated patients was still considerable during the follow-up. Our results support the role of abnormal hemorheological parameters in the development of myocardial ischemia and draw attention to the rheologic risk of these patients. The results of platelet aggregation measurements show the insufficiency of antiplatelet therapy at some cases and confirm the importance of guided secondary prevention.

Prospective randomized trial demonstrates that postoperative administration of glycyl-glutamine alleviates the reduction in human leucocyte antigen DR expression on human monocytes induced by surgery

Background

The surface expression of major histocompatibility complex class II antigens (human leucocyte antigen (HLA) DR) on monocytes is a major indicator of the immunocompetence of these cells. Surgery, trauma and inflammation lead to a reduction in HLA-DR expression on monocytes, which is associated with an increased susceptibility to infection and sepsis. The authors have shown surface expression of HLA-DR on human monocytes in vitro. Following trauma or surgery, glutamine synthesis and secretion from skeletal muscle is increased; intracellular concentrations of glutamine, however, are significantly decreased. It was therefore hypothesized that postoperative infusion of glutamine dipeptides might prevent the decrease in HLA-DR expression on monocytes.

Methods

Thirty patients undergoing major abdominal surgery were allocated randomly to receive either 1500 ml Vamin (an amino acid solution containing no glutamine) (controls) or an isonitrogenic formulation containing Vamin and glycyl-glutamine (35 g glutamine) (GLY-GLN) or Vamin and alanyl-glutamine (35 g glutamine) (ALA-GLN) as a continuous infusion over 48 h after operation. The operations performed included oesophagectomy (three), gastrectomy (four), partial pancreatoduodenectomy (ten), hemihepatectomy (one) and drainage surgery of the biliary/pancreatic duct (ten). Immediately after the operation and 48 h later blood samples were collected for determination of HLA-DR expression of monocytes in vitro by flow cytometry.

Results

The groups were comparable with respect to age, sex distribution and operating time. In the GLY-GLN group mean HLA-DR expression of monocytes at 48 h was significantly better preserved than in controls.

Conclusion

Postoperative infusion of GLY-GLN alleviates the immunosuppression induced by surgery. GLY-GLN may be superior to ALA-GLN because of the distinct immunological effect of glycine and alanine. The observed GLY-GLN-specific preservation of HLA-DR on monocytes following surgery may contribute to the prevention of infectious complications in patients undergoing major abdominal surgery.

Effects of sorbent suspension dialysis on plasma amino acid levels in cirrhotic patients with refractory hepatic encephalopathy

In cirrhotic patients, plasma amino acid levels are severely deranged. A decreased ratio of branched-chain to aromatic amino acids (Fischer ratio) has been implicated in the pathogenesis of hepatic encephalopathy. In this prospective study, we investigated the effects of extracorporeal detoxification on amino acid levels using a sorbent suspension dialysis system. Twenty patients with documented cirrhosis and hepatic encephalopathy grade II-III not responding to standard treatment were randomized to receive either six hours of sorbent dialysis and standardized conventional medical treatment or ongoing medical treatment alone. In contrast to previous uncontrolled studies, no significant effect on amino acid levels, Fischer ratio or clinical grade of hepatic encephalopathy was detected in either treatment group. In conclusion, a 6-hour treatment with sorbent dialysis did not significantly influence plasma levels of amino acids and did not ameliorate the clinical grade of hepatic encephalopathy.

Thermal denaturation of Bungarus fasciatus acetylcholinesterase: Is aggregation a driving force in protein unfolding?

A monomeric form of acetylcholinesterase from the venom of Bungarus fasciatus is converted to a partially unfolded molten globule species by thermal inactivation, and subsequently aggregates rapidly. To separate the kinetics of unfolding from those of aggregation, single molecules of the monomeric enzyme were encapsulated in reverse micelles of Brij 30 in 2,2,4-trimethylpentane, or in large unilamellar vesicles of egg lecithin/cholesterol at various protein/micelle (vesicle) ratios. The first-order rate constant for thermal inactivation at 45 degrees C, of single molecules entrapped within the reverse micelles (0.031 min(-1)), was higher than in aqueous solution (0.007 min(-1)) or in the presence of normal micelles (0.020 min(-1)). This clearly shows that aggregation does not provide the driving force for thermal inactivation of BfAChE. Within the large unilamellar vesicles, at average protein/vesicle ratios of 1:1 and 10:1, the first-order rate constants for thermal inactivation of the encapsulated monomeric acetylcholinesterase, at 53 degrees C, were 0.317 and 0.342 min(-1), respectively. A crosslinking technique, utilizing the photosensitive probe, hypericin, showed that thermal denaturation produces a distribution of species ranging from dimers through to large aggregates. Consequently, at a protein/vesicle ratio of 10:1, aggregation can occur upon thermal denaturation. Thus, these experiments also demonstrate that aggregation does not drive the thermal unfolding of Bungarus fasciatus acetylcholinesterase. Our experimental approach also permitted monitoring of recovery of enzymic activity after thermal denaturation in the absence of a competing aggregation process. Whereas no detectable recovery of enzymic activity could be observed in aqueous solution, up to 23% activity could be obtained for enzyme sequestered in the reverse micelles.

Administration of proteolytic enzymes bromelain and trypsin diminish the number of CD4+ cells and the interferon-gamma response in Peyer's patches and spleen in endotoxemic balb/c mice

Recent publications revealed that bromelain exerts a marked effect on T-cell response by inhibiting T-cell signal transduction. These experimental studies may help to explain former clinical investigations showing that Phlogenzym (PHL), a preparation consisting of the proteases bromelain and trypsin and the antioxidant rutosid, ameliorate certain diseases with an underlying inflammatory process. In this study, we showed that orally administered PHL significantly reduced lymphocyte subpopulations in Peyer's patches (PPs) of healthy and endotoxemic mice. Similarly, the number of splenic lymphocytes in endotoxin-boostered mice was significantly lowered by PHL. The effect of PHL was more pronounced on T cells than on B cells leading especially to a diminution of CD4+ cells. Moreover, PHL pretreatment decreased IFN-gamma mRNA in PPs and spleen of endotoxemic mice. These results reveal that PHL may ameliorate inflammatory process by reducing the number of CD4+ cells and by diminishing INF-gamma mRNA levels.

In-vitro analysis of the contribution of CYP2D6.35 to ultra-rapid metabolism

From 10 to 30% of CYP2D6 ultra-rapid metabolizers of Caucasian origin harbor alleles with duplicated or amplified functional CYP2D6 genes. Recently, the CYP2D6*35 allele has been reported to be more frequent in ultra-rapid metabolizing subjects than in extensive metabolizers, suggesting a possible role of this variant in CYP2D6 duplication-negative ultra-rapid metabolizing subjects. In this study, we examined the functional consequences of the Val11Met, Arg296Cys and Ser486Thr amino acid substitutions associated with the CYP2D6*35 on the expression and catalytic activity of the variant enzyme, heterologously expressed in yeast. Our results indicate that the functional activity and level of expression of recombinant CYP2D6.35 are comparable with those of the wild-type enzyme, thus precluding the hypothesis that the high level of enzyme activity in CYP2D6 duplication-negative ultra-rapid metabolizing subjects is a consequence of the expression of a more catalytically effective CYP2D6.35 enzyme.

Release of non-neuronal acetylcholine from the isolated human placenta is mediated by organic cation transporters

1. The release of acetylcholine was investigated in the human placenta villus, a useful model for the characterization of the non-neuronal cholinergic system. 2. Quinine, an inhibitor of organic cation transporters (OCT), reduced acetylcholine release in a reversible and concentration-dependent manner with an IC(50) value of 5 microM. The maximal effect, inhibition by 99%, occurred at a concentration of 300 microM. 3. Procaine (100 microM), a sodium channel blocker, and vesamicol (10 microM), an inhibitor of the vesicular acetylcholine transporter, were ineffective. 4. Corticosterone, an inhibitor of OCT subtype 1, 2 and 3 reduced acetylcholine in a concentration-dependent manner with an IC(50) value of 2 microM. 5. Substrates of OCT subtype 1, 2 and 3 (amiloride, cimetidine, guanidine, noradrenaline, verapamil) inhibited acetylcholine release, whereas carnitine, a substrate of subtype OCTN2, exerted no effect. 6. Long term exposure (48 and 72 h) of villus strips to anti-sense oligonucleotides (5 microM) directed against transcription of OCT1 and OCT3 reduced the release of acetylcholine, whereas OCT2 anti-sense oliogonucleotides were ineffective. 7. It is concluded that the release of non-neuronal acetylcholine from the human placenta is mediated via organic cation transporters of the OCT1 and OCT3 subtype.

Is peripheral blood a reliable indicator of acute oxidative stress following heart ischemia and reperfusion?

BACKGROUND

Reactive oxygen species (ROS) play a crucial role in membrane damage in ischemic-reperfusion syndromes. The aim of our work was to determine whether blood samples taken from a peripheral vein are a reliable indicator to reflect the development of oxidative stress following acute heart ischemia and reperfusion.

MATERIAL AND METHODS

In a dog model, the left descending coronary artery (LAD) was occluded for 60 min followed by 60 minutes of reperfusion. The lipid peroxidation marker malondialdehyde (MDA), endogenous antioxidants reduced glutathione (GSH), the activity of superoxide dismutase (SOD) enzyme and the stimulated radical production of isolated neutrophil granulocytes (PMN) were measured simultaneously from the peripheral vein and the coronary sinus before and at the end of the LAD occlusion, and again during reperfusion.

RESULTS

MDA and SOD values increased during reperfusion. At the end of 1 hour the reperfusion changes in the coronary sinus were significant (p<0.05). GSH increased in the femoral vein, but decreased in the coronary sinus. The radical-producing capacity of PMNs decreased by the end of LAD occlusion, and a further significant decrease was measured during reperfusion in the coronary sinus (p<0.01). In the peripheral venous blood samples the decrease of PMN radical production became significant only at 30 minutes of reperfusion (p<0.02), and the earlier difference between the coronary sinus and the femoral vein tended to level out following 60 minutes of reperfusion.

CONCLUSIONS

During early reperfusion following myocardial ischemia coronary sinus blood sampling gives an earlier indication of myocardial damage. At a later phase, peripheral blood samples may also be informative regarding the altered balance between ROS production and the antioxidant capacity.