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Biomedical subjects

E Zoucas

Publications and source records attributed to E Zoucas.

At least 19 recordsLinked to original sources
PubMed2003

Local infusion of the nitric oxide donor Sin-1 after angioplasty. Effects on intimal hyperplasia in porcine coronary arteries.

PURPOSE: To investigate the development of intimal hyperplasia in response to percutaneous transluminal coronary angioplasty (PTCA) followed by local delivery of the nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1). MATERIAL AND METHODS: Overdilation PTCA was performed in coronary arteries in 20 healthy pigs. One of the dilated segments was additionally treated with local delivery of SIN-1 for 10 min. Segments distal to the treated part of the arteries served as controls. Arteries were radiographically depicted and analyzed after 1 and 8 weeks for actin, myosin and intermediate filaments (IF), nitric oxide synthetase (NOS) and histological evaluation. RESULTS: Segments treated with PTCA+SIN-1 showed a significantly (p=0.03) larger luminal diameter compared with PTCA only treated segments. The luminal loss after SIN-1 was not significant compared with the diameter prior to treatment. Endothelial NOS content was significantly lower in the PTCA+SIN-1 group compared with the PTCA group after 1 (p=0.03) and 8 weeks (p=0.013). IF/actin ratio after 1 week was significantly increased in PTCA-treated segments compared with untreated controls (p=0.004), and compared with PTCA+SIN-1-treated segments (p=0.004). CONCLUSION: PTCA-induced intimal hyperplasia was potently inhibited by local delivery of the NO donor SIN-1. Momentary events at the time of injury play a significant role in the development of intimal hyperplasia and long-lasting down-regulation of the endothelial NOS expression after SIN-1 exposure is suggested. The IF/actin ratio can be useful as an early marker of intimal hyperplasia.

Angioplasty, Balloon, Coronary↗
PubMed2001

Effect of selective denervation of the rat pancreas on pancreatic endocrine function.

The purpose of this study was to investigate the influence of selective denervation of the rat pancreas on hormone secretion and on peripheral insulin sensitivity. Thirteen rats, 7 denervated and 6 sham operated, received an intravenous glucose challenge for 30 min. The basal plasma levels of insulin, glucagon and glucose did not differ between the two groups. An augmented insulin response to glucose was detected in the denervated group, whereas the glucagon response was unaffected. Glucose tolerance was marginally improved. Twenty-four rats, 12 denervated and 12 sham operated, received a constant infusion of glucose, insulin, epinephrine and propranolol in order to inhibit the endogenous insulin release and thus evaluate insulin sensitivity. No significant change in insulin sensitivity could be detected during our experimental conditions. We conclude that selective denervation brings about an increased insulin response to glucose, probably by interrupting a catecholaminergic negative tone on the beta-cell. The sympathectomized animals did not disclose any apparent changes in peripheral insulin sensitivity.

Animals↗
PubMed2001

Differential roles of endogenous nitric oxide on neural regulation of basal exocrine pancreatic secretion in intact and denervated pancreas.

BACKGROUND: Autonomic nerves and humoral factors regulate pancreatic secretion. Nerves containing nitric oxide (NO) synthase (NOS) are in close proximity and located within cholinergic, adrenergic and sensory nerve bundles. Yet, the interactive mechanisms between various nerve populations remain elusive. AIMS: To evaluate the role of endogenous NO in basal exocrine pancreatic secretion in the extrinsically denervated rat pancreas. METHODS: Male Sprague-Dawley rats were assigned to 2 groups of 11 animals. The first group of sham-operated animals served as controls. In the second group extrinsic pancreatic innervation was surgically interrupted. One week later, after selective catheterization of the celiac axis and the bile-pancreatic duct, the animals received intra-arterial infusions of NG-nitro-L-arginine (L-NNA; 0.48 mg/kg b.w./h) followed by intra-arterial infusions of L-arginine (110 mg/kg b.w./h). Total protein and amylase were measured in bile-pancreatic secretions collected at 15-min intervals. RESULTS: In controls, total protein and amylase output showed a biphasic secretion pattern with an increase during L-NNA infusion followed by a decrease when the infusion ceased and further augmentation 1 h later. In denervated animals, L-NNA caused a sustained decrease in pancreatic secretion followed by an increase 1 h later. Infusion of L-arginine at the time of maximum decrease slowed the second phase of protein and amylase output in sham-operated rats, but accentuated the onset of secretion in denervated animals. CONCLUSION: Inhibition of endogenous NO release was shown to increase baseline secretion in the intact pancreas. Superposition of extrinsic denervation on neural NOS-blockade decreased basal exocrine secretion, indicating that intra-pancreatic NO release is regulated by extra-pancreatic nerves.

Amylases↗
PubMed1999

Differences in endothelial injury after balloon angioplasty, insertion of balloon-expanded stents or release of self-expanding stents: An electron microscopic experimental study.

PURPOSE: To evaluate which of six different commonly available stents inserted into an artery without percutaneous transluminal angioplasty (PTA) causes the least endothelial damage. To compare the degree of endothelial injury after insertion of such a stent with injury caused by PTA. METHODS: Twelve healthy pigs were used in the experiments. In the first part of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contralateral iliac artery. The pigs were killed immediately after the procedure and resected specimens examined after fixation, using scanning electron microscopy. RESULTS: All procedures but two were accomplished successfully. More endothelium was preserved after insertion of self-expanding stents with large spaces between the wires, compared with stents with small spaces and balloon-expanded stents. After insertion of self-expanding stents with large spaces, 50.1% +/- 16.4% of the endothelium remained intact, compared with only 5.6% +/- 7.7% after PTA. The difference was statistically significant (p < 0.001). CONCLUSION: Self-expanding stents with large spaces between the wires, inserted without PTA, cause less damage to the endothelium than other stents and significantly less damage than PTA.

Angioplasty, Balloon↗
PubMed1999

Bilateral thoracoscopic splanchnicectomy: effects on pancreatic pain and function.

OBJECTIVE: To evaluate prospectively the effect of bilateral thoracoscopic splanchnicectomy on pancreatic pain and function. SUMMARY BACKGROUND DATA: Severe pain is often the dominant symptom in pancreatic disease, despite a wide variety of methods used for symptom relief. Refinement of thoracoscopic technique has led to the introduction of thoracoscopic splanchnicectomy in the treatment of pancreatic pain. METHODS: Forty-four patients, 23 with pancreatic cancer and 21 with chronic pancreatitis, were included in the study and underwent bilateral thoracoscopic splanchnicectomy. Effects on pain (visual analogue scale) and pancreatic function (standard secretin test, basal serum glucose, plasma insulin, and C-peptide) were measured. RESULTS: Four patients (9%) required thoracotomy because of bleeding. There were no procedure-related deaths. The mean duration of follow-up was 3 months for cancer and 43 months for pancreatitis. Pain relief was evident in the first postoperative week and was sustained during follow-up, the average pain score being reduced by 50%. All patients showed a decrease in consumption of analgesics. Neither endocrine nor exocrine function was adversely affected by the procedure. CONCLUSIONS: Bilateral thoracoscopic splanchnicectomy is beneficial in the treatment of pancreatic pain and is not associated with deterioration of pancreatic function.

Aged↗
PubMed1998

Electrolytic stent in the normal bile duct. An experimental study.

PURPOSE: To evaluate and compare changes in the bile-duct wall after the insertion of electrolytic and nonelectrolytic stents. MATERIAL AND METHODS: The electrolytic stents were composed of 3 different layers (iron, isolating polyethylene and tantalum) and were implanted surgically in the bile duct of 8 healthy pigs. The nonelectrolytic stents were also composed of 3 layers (2 layers of tantalum and an isolating layer of polyethylene) and were implanted surgically in the bile ducts of 9 healthy pigs. After an observation time of 8 weeks, the pigs were killed and the bile ducts were excised and sent for histopathological examination. RESULTS: One pig was killed after the procedure owing to postoperative complications; all the other pigs survived without complications. Migration of the stent to the bowel occurred in 4 pigs. A slight inflammatory reaction was seen at histopathological examination in 6 pigs with the electrolytic stent and in 6 pigs with the nonelectrolytic stent. There was no difference in the specimens from pigs with electrolytic and nonelectrolytic stents. CONCLUSIONS: The electrolytic stents did not cause more changes in the normal bile-duct wall than the nonelectrolytic stents.

Animals↗
PubMed1997

Function of reduced-size liver transplant in the rat.

We have studied the function of partial orthotopic liver transplantation in the rat by evaluating prothrombin time (PT), liver blood flow, basal and glucose-stimulated insulin secretion and glucose tolerance, and the reticuloendothelial function (RES) in hepatectomized rats subjected to partial liver transplantation. A graft corresponding to 68% of a normal liver was transplanted to totally hepatectomized rats. Comparison was made between control rats and rats subjected to 32% liver resection. PT was not significantly different in the transplanted group compared with liver-resected and control rats. Laser Doppler flowmetry showed that at 28 days after surgery, blood flow had increased in the transplanted livers. Furthermore, on the third day after transplantation, basal plasma insulin was increased and the plasma insulin response to glucose was exaggerated, suggesting reduced insulin action and impaired insulin degradation. Finally, uptake of radioactive-labeled E. coli bacteria, as a measure of RES function, was not compromised in transplanted animals. Based on these results, we conclude that reduced-size liver transplant in out-bred rats results in fast normalization of liver function after surgery although, immediately after surgery, glucose intolerance is seen.

Animals↗
PubMed1997

The effect of selective sympathetic denervation on pancreatic exocrine secretion.

The purpose of this study was to investigate the influence of selective sympathetic denervation of the rat pancreas on exocrine secretion and to study whether the observed effects were due to pancreatic trophism. Sprague-Dawley rats were divided into two groups. One group underwent selective sympathetic denervation by skeletonizing the superior and inferior pancreaticoduodenal and splenic arteries. The other group underwent simple laparotomy and served as controls. One week after the operation a catheter was introduced into the bile-pancreatic duct and pancreatic juice was collected at 30-min intervals for 4 h. The output of bicarbonate, total protein, amylase, trypsin, chymotrypsin, lipase, colipase and carboxyesterlipase were determined. Following denervation secretion of pancreatic enzymes was significantly enhanced compared with sham-operated animals. We did not find any signs of pancreatic trophism 1 week after denervation.

Amylases↗
PubMed1997

Proliferative response in smooth muscle cells after angioplasty or insertion of self-expanding stents. An experimental study in pigs.

PURPOSE: Evaluation of the early proliferative reaction of smooth muscle cells (SMC) in the media of the artery following percutaneous transluminal angioplasty (PTA), compared with the reaction on insertion of self-expandable stents. MATERIAL AND METHODS: In 6 healthy pigs, one iliac artery was overdilated with an 8-mm diameter angioplasty balloon. A self-expanding Nitinol stent, OD 8 mm, was inserted into the contralateral iliac artery without previous dilatation. The nuclei of the proliferating SMC in the media of the artery were labelled by intravenous administration of 5-bromo-2-deoxy-uridine and cells in S-phase counted 24 h after the procedure. RESULTS: The mean number of proliferating nuclei of the SMC increased significantly more after PTA (p < 0.05) than after the insertion of a stent. CONCLUSION: Early proliferative reaction of the SMC is more pronounced after PTA than after insertion of the self-expanding stent.

Alloys↗
PubMed1997

Differential effects of nitric oxide synthase modulation on porcine systemic and pulmonary circulation in vivo.

OBJECTIVE: To study and compare the effects of inhibiting endothelial nitric oxide synthase on systemic and pulmonary circulation in an in vivo model. DESIGN: Prospective, randomized, controlled study. SETTING: Laboratory for experimental surgery at a university medical center. SUBJECTS: Seventeen anesthetized, mechanically ventilated pigs. INTERVENTIONS: To produce a stable and continuous stimulation of endothelial nitric oxide synthase, an infusion of acetylcholine was given to one group of animals (n = 5) in a dose that decreased mean arterial pressure by 15%. After 45 mins, N(G)-monomethyl-L-arginine (L-NMMA) was given in a dose of 3 mg/kg for 5 mins in order to inhibit the enzyme. A second dose of 10 mg/kg was given 30 mins later. L-arginine was then given in a dose of 100 mg/kg to reverse the inhibition. One group of animals (n = 6) received a single dose of indomethacin (2.5 mg/kg) 15 mins after the start of acetylcholine infusion. L-NMMA and L-arginine were then given. In a control group (n = 5), the effects of L-NMMA and L-arginine were studied without acetylcholine. Circulatory parameters were monitored and resistance indices were calculated via arterial, central venous, and pulmonary artery catheters. MEASUREMENTS AND MAIN RESULTS: In control animals, 3 and 10 mg/kg of L-NMMA induced an increase in mean arterial pressure of 14% and 25%, respectively, with similar increases in systemic vascular resistance. Mean pulmonary arterial pressure increased by 22% and 48%, respectively. Acetylcholine lowered mean arterial pressure by 15% and did not affect the relative changes induced by L-NMMA. Acetylcholine had no effect on pulmonary resting tone but enhanced the pulmonary hypertension and increase in resistance induced by L-NMMA. This enhancement was abolished by indomethacin, which produced systemic hypertension while no effect on pulmonary pressure was seen. CONCLUSIONS: A basal release of nitric oxide contributes to the maintenance of normal vascular tone in the anesthetized pig. Stimulation of endothelial nitric oxide synthase by acetylcholine did not result in any further pulmonary vasodilation as was seen in the systemic circulation. Inhibition of nitric oxide synthase had a greater effect on pulmonary pressure than on systemic pressure. However, this difference was abolished by the administration of indomethacin. Increased nitric oxide release or acetylcholine itself seems to stimulate the production of a vasoconstricting prostanoid in the pulmonary circulation.

Acetylcholine↗
PubMed1996

Thoracoscopic Splanchnicectomy for Chronic, Severe Pancreatic Pain.

Fourteen patients with pancreatic cancer, 2 with cancer of the papilla of Vater, and 14 with chronic pancreatitis were operated on with bilateral thoracoscopic splanchnicectomy caused by severe chronic pain. The median follow-up time was 13 months. Twenty patients were followed up for 3 months and 14 for at least 6 months. The surgical results were evaluated prospectively, both with visual analogue scale (VAS) and with documentation of the consumption of analgesics at elective follow-up after 1 week and 1, 3, 6, and 12 months postoperatively. All 30 patients stated that the characteristics of their pain had changed at recovery from anaesthesia, but only 6 of them reported immediate complete pain relief. All but 1 of the 14 patients with chronic pancreatitis had clearly reduced pain as evaluated by VAS 1 month after the operation, and this beneficial effect remained for the whole study period. Furthermore, the need for analgesics decreased. Also, in the 16 patients with cancer, there was on average a marked relief of pain from 1 week and onwards. The 6 cancer patients with survival more than 3 months had reduced pain for the remaining period of their lives. It seems that the final pain relief is persistent as is the reduced consumption of analgesics. There was no correlation between the number of cut nerves and pain relief as evaluated by VAS. Three patients were reoperated on for intrathoracic bleeding the evening after the operation, and one had transient pain located to one of the port sites. Otherwise, there were no postoperative complications. The operation time was short and the length of hospital stay in most patients was 24 hours or less. It was concluded that thoracoscopic splanchnicectomy appears to be a promising and relatively simple treatment for severe chronic pancreatic pain. Further studies are needed to establish its role in the management of intractable pancreatic pain.

Journal Article↗
PubMed1996

Selective microsurgical sympathetic denervation of the rat pancreas.

Autonomic nerves have been implicated in the regulation of endocrine and exocrine pancreatic secretion. The purpose of the present study was, therefore, to develop a simple, reproducible technique for selective sympathetic denervation of the rat pancreas. Under ether anesthesia a midline laparotomy was performed, the pancreas and spleen were freed from adhesions. The peritoneum was incised over the superior and inferior pancreaticoduodenal arteries and the splenic artery at their origin. The incised areas were stained with 1% toluidine blue solution. The pancreaticoduodenal and splenic nerves were visualized and resected. 1, 2 and 3 weeks after the denervation procedure the norepinephrine (NE) content of the pancreatic tissue was determined. Cholinergic and nitric oxide synthetase (NOS)-immunoreactive nerve structures were identified by immunohistochemistry 1 week after denervation. In denervated tissue the NE content after 1 week was 98% lower than measured in controls. With time, there was a gradual increase of the NE content, although it reached only 25% of the values measured in sham-operated animals at 3 weeks. There was no concomitant denervation of the duodenum. Cholinergic and NOS nerve structures were still present 1 week after denervation.

Animals↗
PubMed1994

Circulatory and ventilatory effects of intermittent nitric oxide inhalation during porcine endotoxemia.

The effects of intermittent inhalation of 57 ppm nitric oxide (NO) were studied in eight anesthetized, ventilated pigs given a continuous infusion of Escherichia coli endotoxin. Seven animals served as controls. By administering NO synchronized with inspiration and close to the orotracheal tube, measurable amounts of the toxic metabolite, NO2, in the inspiratory gas mixture were avoided. No direct systemic effects of NO inhalation were seen, but through counteracting pulmonary vasoconstriction, a fall in cardiac output was delayed. Nitric oxide effectively attenuated the initial peak rise in mean pulmonary artery pressure and resistance, both returning to control levels after cessation of NO. These effects were reproduced during later phases of endotoxemia, giving further proof to the role of gaseous NO as a selective pulmonary vasodilator. Nitric oxide diminished pulmonary shunting, but unimpaired oxygenation was preserved only during the first inhalation period. Leukocyte counts decreased drastically and platelet aggregation was enhanced, but after 1.5 hours of endotoxin infusion, platelet hyperaggregation was maintained in the NO group while it decreased in the control group.

Administration, Inhalation↗
PubMed1990

Impaired hemostasis following denervation of the rat spleen.

The possibility that the noradrenergic system might play a role in modulating platelet activation within the spleen was examined. A new microsurgical model for achieving selective denervation of the rat spleen was created. The denervation procedure resulted in a 96% reduction of the norepinephrine content in splenic tissue. One week after splenic denervation, animals were subjected to standardized splenic resection or standardized transection of mesenteric microvessels. The denervation of the spleen was accompanied by a highly significant increase in bleeding time and blood loss at both locations of trauma. Furthermore, platelet function, measured as adenosine diphosphate (ADP)-induced aggregation, decreased significantly after denervation, indicating that platelet aggregation might be modulated by noradrenergic fibres within the spleen.

Adenosine Diphosphate↗
PubMed1990

Inhibition of platelet aggregation by granulocytes stimulated during experimental trauma.

The effect of granulocytes, stimulated in vivo by standardized soft tissue trauma, on the aggregation of autologous platelets in vitro, was studied in the pig. Platelet aggregation induced by ADP and arachidonic acid was inhibited when platelets harvested before trauma were incubated with granulocytes obtained 5 min after trauma. The granulocytes were separated from the platelets during the incubation by enclosure in dialysis tubes. Platelet inhibition was evident when the cell cohorts were suspended in cell-free medium as well as in autologous plasma extracted before trauma. In addition, incubation of platelets harvested before trauma with plasma obtained after trauma decreased platelet aggregation. In conclusion, granulocytes stimulated in vivo inhibited platelet function in vitro. Platelet inhibitory activity was shown to be related with the granulocytes per se, but also with factors present in plasma after trauma.

Adenosine Diphosphate↗
PubMed1988

The effects of pneumatic antishock garments in the treatment of critical abdominal injuries in rats.

Thirty rats were subjected to a standardized critical aortic injury and divided into six groups. In addition to controls, the animals were treated with a pneumatic antishock garment (PASG), massive intravenous or intra-aortic saline infusion, or PASG in combination with either massive intravenous or intra-aortic saline infusion. Twenty-six rats were subjected to a standardized hepatic injury and divided into four groups. In addition to controls, the animals were treated with PASG, massive intravenous saline infusion, or PASG in combination with massive intravenous saline infusion. These animals were allowed to bleed for 5 minutes before the treatment was started. The treatment with PASG alone prolonged the median survival time significantly from 7 min in the control group to greater than 120 min in the PASG group in rats with an aortic injury and from 33 to greater than 120 min in rats with a hepatic injury. Intravenous infusion of saline did not prolong the median survival time. Intravenous infusion in combination with PASG did not have any positive effects on median survival time or median mean aortic pressure and failed to prolong the median survival time significantly in rats with a liver injury, as six out of eight animals developed a lethal pulmonary edema.

Abdominal Injuries↗
PubMed1987

Effect of acetaldehyde on rat platelet aggregation in vivo and in vitro.

The effect of acetaldehyde on primary hemostasis and platelet aggregation was studied in vivo and in vitro in the rat. Acetaldehyde was found in circulation following ethanol intoxication or was present after direct i.v. injection. In vitro, acetaldehyde was added to whole blood or platelet plasma suspension. Bleeding time and blood loss were increased upon ethanol intoxication and immediately after i.v. infusion of acetaldehyde. The intrinsic coagulation system, assayed by APT-time, was unaffected. In vivo, ADP and collagen-induced platelet aggregation was inhibited upon the presence of acetaldehyde. In vitro, inhibition of platelet aggregation was observed when acetaldehyde was added to blood, while the addition of the compound to plasma did not affect platelet function.

Acetaldehyde↗