Monitoring and recovery of hyperglycaemia-induced endothelial dysfunction with rheopheresis in diabetic lower extremity ulceration with hyperviscosity

AIMS

Rheopheresis is an extracorporeal haematotherapy that improves haemorheological status by filtering proteins that enhance blood viscosity. It also has anti-inflammatory effects by removing inflammatory cytokines. Our study aims to examine the effects of rheopheresis on the endothelial status in diabetic lower extremity ulceration.

METHODS

In vitro experiments were performed in a HUVEC model to mimic hyperglycaemic stress. We determined the changes in gene expression levels of IL-6, IL-8, TNF-alpha, endothelin convertase enzyme, ET-1, and NO synthase, as well as the ROS and intracellular GSH levels upon hyperglycaemia. In in vivo studies, two rheopheresis procedures were performed on seven patients with diabetic lower extremity ulceration with hyperviscosity, and we measured the changes in plasma concentrations of ET-1, TXB2, SOD enzyme activity, and extracellular components of the glutathione pool depending on treatments.

RESULTS

Our results showed that hyperglycaemia increases endothelial expression of inflammatory cytokines, ET-1, and endothelin convertase enzyme, while NO synthase was decreased. As a result of rheopheresis, we observed decreased ET-1 and TXB2 concentrations in the plasma and beneficial changes in the parameters of the glutathione pool.

CONCLUSION

To summarize our results, hyperglycaemia-induced oxidative stress and endothelial inflammation can be moderated by rheopheresis in diabetic lower extremity ulceration with hyperviscosity.

Mentalizing abilities and serum lipid levels in adult MDD patients with childhood maltreatment – preliminary results

Introduction

Childhood maltreatment (CM) contributes to negative mental and physical health outcomes including major depressive disorder (MDD), and an elevated risk for cardiovascular disease (CDV) in adults. Also, childhood maltreatment can be related to mentalizing deficits in MDD. Cardio-metabolic diseases often coincide with MDD and worsen its course and outcome. Little is known on the interplay of these factors.

Objectives

We examined MDD patients with and without CM to explore the effects of CM on serum lipid and lipoprotein levels and assessed their mentalizing abilities. Self-oriented mentalizing was operationalized as emotional self-awareness/alexithymia, other-oriented mentalizing was defined as theory of mind (ToM).

Methods

MDD patients (N=42) and healthy controls (n=20) matched in age, sex, and lifestyle were investigated. Total cholesterol, triglycerides, high- and low-density lipoproteins (HDL-C and LDL-C), body mass index, and exercise in a typical week were measured. Beck Depression Inventory, Childhood Trauma Questionnaire, Toronto Alexithymia scale, and the Reading the mind in the Eyes Test were used to assess clinical symptoms, mentalizing abilities and CM.

Results

After controlling for depressive symptom severity, demographic and lifestyle variables, CM was found to be a strong predictor of serum lipid alterations. Mentalizing deficits correlated with CM. Serum triglycerides, HDL-C were significant predictors of ToM performance (P<0.05, and P=0.005) and alexithymia (P< 0.05, and P< 0.05) in the MDD group.

Conclusions

Several, inter-correlated pathways may mediate the undesirable effects of CM on the course and outcome of MDD. According to our preliminary results, diminished self-awareness and ToM can be possible mediating factors.

Disclosure

This work was financially supported by the Hungarian Brain Research Program (2017-1.2.1-NKP-2017-00002)

In Vitro and In Vivo Studies of a Verapamil-Containing Gastroretentive Solid Foam Capsule

Gastroretentive systems may overcome problems associated with incomplete drug absorption by localized release of the API in the stomach. Low-density drug delivery systems can float in the gastric content and improve the bioavailability of small molecules. The current publication presents verapamil–HCl-containing solid foam prepared by continuous manufacturing. Production runs were validated, and the foam structure was characterized by micro-CT scans and SEM. Dissolution properties, texture changes during dissolution, and floating forces were analyzed. An optimized formulation was chosen and given orally to Beagle dogs to determine the pharmacokinetic parameters of the solid foam capsules. As a result, a 12.5 m/m% stearic acid content was found to be the most effective to reduce the apparent density of capsules. Drug release can be described by the first-order model, where 70% of verapamil dissolved after 10 h from the optimized formulation. The texture analysis proved that the structures of the solid foams are resistant. Additionally, the floating forces of the samples remained constant during their dissolution in acidic media. An in vivo study confirmed the prolonged release of the API, and gastroscopic images verified the retention of the capsule in the stomach.

The first local experiences with rheopheresis treatment

Összefoglaló. Háttér: A rheopheresis egy szelektív, extracorporalis, kettős kaszkádfiltrációs eljárás, mely előzetes plazmaszeparációt követően egy speciális filter segítségével kivonja a vérplazmából a hiperviszkozitásért felelős komponenseket, úgymint alacsony sűrűségű lipoprotein, lipoprotein(a), triglicerid, koleszterin, fibrinogén, α2-makroglobulin, Von Willebrand-faktor, immunglobulin-M. Módszer és Betegek: Klinikánkon az elmúlt 5 évben MONET filter alkalmazásával összesen 80 kezelést végeztünk hiperviszkozitással összefüggő, időskori száraz maculadegeneratióban, diabeteses alsó végtagi fekélyben, illetve neuropathiában. Eredmények: A dolgozatban beszámolunk kedvező klinikai tapasztalatainkról, a viszkozitás, a klinikai tünetek és az elektroneurográfiai paraméterek tükrében. Orv Hetil. 2021; 162(10): 375-382.

SUMMARY

BACKGROUND

Rheopheresis is a selective, extracorporeal, double cascade filtration method. After a previous plasma separation, with the help of a special filter it extracts compounds from blood plasma which are responsible for hyperviscosity such as low-density lipoprotein, lipoprotein(a), triglyceride, cholesterine, fibrinogen, α2-macroglobulin, Von Willebrand factor, immunoglobulin M.

METHOD AND PATIENTS

In the past 5 years, with the application of MONET filter we performed 80 therapies to treat age-related macula degeneration, diabetic foot ulcers and neuropathy which are complicated with hyperviscosity.

RESULTS

The review describes our benefical clinical experiences in consideration of viscosity, clinical symptoms and electroneurography parameters. Orv Hetil. 2021; 162(10): 375-382.

The present and the future of medical simulation education in Hungary

Simulation-based medical education aims to model clinical situations and tasks using simulators, computers or even human beings. By using this system, the students are able to learn and master technical, also non-technical skills in lifelike situations. This publication contains a historical review of simulation-based education system, and its actualities in Hungary. Simulation has an unquestionable role in medical education. It is beneficial for the students, for the teachers, and for the teaching hospitals as well, since it saves clinical equipment and reduces the human burden. Its main purpose is to establish connection between theoretical and practical competencies, preparing the students for real medical challenges. Simulation has been a known teaching method for centuries, but only the 21st century brought real breakthrough due to the sudden development of technology. As a result of the recent years' innovative development and accepted innovative solutions, the modeling of complex medical procedures turned into more realistic. In Hungary, 3D-printed tools, virtual reality and augmented reality approaches are already adopted for education purposes. The national simulation network contains 3 universities and 16 hospitals. The initial developments are shown to be successful, as simulation-based training is progressively involved in undergraduate and post-graduate education, and the overall feedback is positive from the involved students. The evolvement of comprehensive national methodology for education has started also, by publishing reference books. This review is about the state of the national simulation education and offers development possibilities. Orv Hetil. 2020; 161(26): 1078-1087.

Sepsis-associated encephalopathy: A review of literature

Sepsis is a leading cause of death in medical and surgical intensive care units (ICUs). Disturbance of consciousness of varying severity is an early warning sign of developing sepsis in the majority of cases. Sepsis-associated encephalopathy (SAE) is the most frequent type of encephalopathy in the ICU and is defined as a state of diffuse cerebral dysfunction caused by the inflammatory response of the body to various infections, where the inflammatory process does not affect the central nervous system (CNS) directly and the primary symptom is a disturbed level of consciousness. The aim of this comprehensive review was to collect the latest scientific knowledge regarding the epidemiology, clinical aspects, pathogenesis, diagnosis, and possible prevention strategies related to SAE.

N,N-dimethyltryptamine Prevents Renal Ischemia-Reperfusion Injury in a Rat Model

BACKGROUND

Ischemia reperfusion (I/R) injury remains one of the most challenging fields of organ transplantation. It is highly associated with the use of expanded criteria donors that might conclude to delayed graft function or early or late graft failure.

OBJECTIVE

To investigate the metabolic, microcirculatory parameters, and histologic changes under the effect of N,N-dimethyltryptamine (DMT) in a renal I/R model in rats.

METHOD

In 26 anesthetized rats both kidneys were exposed. In the control group (n = 6) no other intervention happened. In 20 other animals, the right renal vessels were ligated, and after 60 minutes the right kidney was removed. The left renal vessels were clamped for 60 minutes then released, followed by 120 minutes of reperfusion. In the I/R group (n = 10), there was no additive treatment, while in I/R + DMT group (n = 10) DMT was administered 15 minutes before ischemia. Blood samples were taken, laser Doppler measurement was performed, and both kidneys were evaluated histologically.

RESULTS

Microcirculation (blood flux units [BFU]) diminished in all groups, but remarkably so in the I/R + DMT group. This group compensated better after the 30th minute of reperfusion. The control and I/R + DMT groups had similar BFUs after 120 minutes of reperfusion, but in the I/R group BFU was higher. Tubular necrosis developed in the I/R and I/R + DMT groups too; it was moderated under DMT effect, and severe without. Histologic injuries were less in I/R + DMT Group compared to non-treated animals.

CONCLUSION

Histologic changes characteristic to I/R injuries were reversible and microcirculation recovered at the end of 120 minutes reperfusion under the administration of DMT. DMT can be used for renoprotection in kidney transplantation.

Hemodynamic consequences of intravenously given E. coli suspension: observations in a fulminant sepsis model in pigs, a descriptive case-control study

BACKGROUND

The aim of the present work was to assess systemic hemodynamic changes using PiCCo monitoring in a porcine model of E. coli-induced fulminant sepsis.

METHODS

Thirty-one healthy female Hungahib pigs were randomly assigned into control (n = 15) or septic groups (n = 16). In the sepsis group Escherichia coli culture was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring in both groups.

RESULTS

Resting hemodynamic parameters were identical in the two groups. In control animals, systemic hemodynamic variables were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60-255) min after starting the injection of E. coli solution. Blood pressure values gradually decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and a decreased stroke volume variation were observed.

CONCLUSIONS

These results may serve as additional pathophysiological information of hemodynamic changes occurring during hypodynamic sepsis and may contribute to a better understanding of the pathomechanism of septic multiple organ failure.

Characteristics of thrombin generation in a fulminant porcine sepsis model

INTRODUCTION

The activation of blood coagulation has been demonstrated in most cases of sepsis, however previous studies in humans could not detect hypercoagulability with global hemostasis assays. In a fulminant porcine sepsis model we analysed coagulation screening tests and thrombin generation to evaluate hemostatic alterations.

MATERIALS AND METHODS

Live Escherichia coli bacteria were inoculated to female pigs and prothrombin time, activated partial thromboplastin time, thrombin time and fibrinogen were measured by coagulometry. Platelet counts, platelet aggregates and platelet phosphatidyl serine (PS) expression were studied, furthermore in in vitro experiments the PS-inducing ability of septic and control plasmas was investigated by flow cytometry. Thrombin generation was carried out by the Ascent Fluoroscan reader and results were evaluated by the Thrombinoscope software.

RESULTS

Clotting assays showed a large variability, but no systematic changes during the 4-hour observation period. Platelet count significantly decreased and the number of platelet aggregates increased already by 2h compared to baseline values and to control animals. Although the increase in platelet PS expression was non-significant in the septic group, the septic plasma elicited PS expression on normal human red blood cells. Thrombin generation became significantly faster, but the quantity of formed thrombin demonstrated both hypo- and hypercoagulability depending on the setting of the assay.

CONCLUSIONS

Enhanced thrombin generation without activators and the PS-inducing capacity of septic plasma are signs of hemostatic activation during fulminant sepsis while the decreased amount of generated thrombin upon tissue factor and phospholipid induced activation demonstrates attenuated thrombin forming ability.

Assessment of cerebral circulation in a porcine model of intravenously given E. coli induced fulminant sepsis

BACKGROUND

The aim of the present work was to assess cerebral hemodynamic changes in a porcine model of E.coli induced fulminant sepsis.

METHODS

Nineteen healthy female Hungahib pigs, 10-12 weeks old, randomly assigned into two groups: Control (n = 9) or Septic Group (n = 10). In the Sepsis group Escherichia coli culture suspended in physiological saline was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring, and cerebral hemodynamics by transcranial Doppler sonography (transorbital approach) in both groups.

RESULTS

In control animals, systemic hemodynamic variables and cerebral blood flow velocities and pulsatility indices were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60-255) minutes after starting the injection of E.coli solution. Blood pressure values gradully decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and an increased stroke volume variation were observed. Mean cerebral blood flow velocity in the middle cerebral artery did not change during the procedure, but pulsatility index significantly increased.

CONCLUSIONS

There is vasoconstriction at the level of the cerebral arterioles in the early phase of experimental sepsis that overwhelmes autoregulatory response. These results may serve as additional pathophysiological information on the cerebral hemodynamic changes occurring during the septic process and may contribute to a better understanding of the pathomechanism of septic encephalopathy.

Is there a connection between postprandial hyperglycemia and IGT related sensory nerve dysfunction?

BACKGROUND AND AIMS

To assess the risk factors for sensory nerve dysfunction in subjects with isolated impaired glucose tolerance (IGT).

METHODS AND RESULTS

Seventy-two people with isolated IGT (WHO 1999 criteria) and 39 gender and age-matched healthy volunteers underwent detailed clinical and neurological assessment including quantitative sensory testing using the Neurometer device (current perception threshold measurement on four limbs at three different frequencies). Sensory nerve dysfunction was defined as at least two abnormalities on any frequencies on the upper or lower limbs. Sensory nerve dysfunction was more prevalent among subjects with IGT compared to controls (58.3 vs. 10.3%, OR: 11.23, 95%CI: 3.57-35.35). This association was not influenced by BMI, systolic and diastolic blood pressure, heart rate and autonomic neuropathy (multiple adjusted OR: 13.87, 95%CI: 3.18-60.58), but further adjustment for glycaemic measures abolished the association (OR: 1.58, 95%CI: 0.07-35.68). Assessing the components of glycaemic measures separately, the association between sensory nerve dysfunction and IGT was not affected by HbA1c (OR: 13.94, 95%CI: 1.84-105.5). It was, however, substantially attenuated by fasting plasma glucose (OR: 6.75, 95%CI: 1.33-34.27) while the significance was lost after adjustment for 120 min postload glucose level (OR: 3.76, 95%CI: 0.26-54.10). In the pooled population assessed, independent determinants of sensory nerve dysfunction were older age, 120 min glucose, higher height and cardiovascular autonomic neuropathy at near significance.

CONCLUSIONS

Sensory nerve dysfunction amongst subjects with IGT was not explained by cardiovascular covariates, only by glycaemic measures. In addition to 120 min glucose, cardiovascular autonomic neuropathy at borderline significance, age, and height were the independent determinants of sensory nerve dysfunction.

[Hemorheological investigations in experimental surgery]

The hemorheological parameters, such as whole blood viscosity, plasma viscosity, hematocrit, fibrinogen concentration as well as the micro-rheological properties of red blood cells (red blood cell deformability and aggregation) play an important role in tissue perfusion. The alternating hemorheological parameters, which are also inter-related, have important effects in determining hemodynamical properties, as well. The altered hemorheological status has a direct effect on endothelial function by changing shear force profile on the endothelial wall, and impairment of red blood cell deformability and aggregation (presence of rigid red blood cell, and enhanced red blood cell aggregation) slows down microcirculation with disturbing capillary perfusion. In experimental surgery vascular clamping and release cause ischemia-reperfusion, which affect red blood cells in many ways: changes pH level, leads to free-radical release, changes osmolarity and lactate and NO concentrations as well as it causes mechanical trauma. Understanding of these pathophysiological processes and determining the extent of reversible-irreversible changes may help to delineate underlying causes in tissue perfusion and microcirculation better, and develop prophylactic and therapeutic possibilities. The challenges of experimental surgery also include the questions of comparability in different measurement methods, and understanding of interspecies-differences of experimental/laboratory animal models in order to increase the relevance of results in terms of applicability for the original, clinical question.

[The spleen in experimental surgery]

The injured but functionally intact spleen can be saved with various surgical techniques. Two of these techniques were developed in our department: partial spleen resection by embracing suture line, and spleen autotransplantation by implantation of spleen chips between the sheets of the greater omentum, the so called "spleen-apron" technique. Functional and structural postsurgical follow-up investigations were developed in the last three decades, including comprehensive laboratory tests (hematological, hemostaseological, hemorheological, enzymological, routine chemical, immunological), imaging procedures (abdominal US, scintigraphic methods, SPECT, as well as NanoSPECT/CT in the last years) with morphological analysis (conventional histological, immunohistochemical, electonmicroscopical), as well as the investigation of the role of hemopoetic stem cells. These investigations confirm the viability of spleen autotransplantation. The implanted spleen chips are able to restore the splenic functions partially following remodellation and recolonisation after neovascularisation. It is a critically important process in the prevention of overwhelming post-splenectomy infection and DIC. This paper summarizes the most important principles and the main conclusions of different experimental animal models.

[Main indicators of educational activity at the Department of Operative Techniques and Surgical Research at the University of Debrecen between 2000-2013]

The authors provide a review about the main parameters of the gradual and postgradual educational activity of the Department of Operative Techniques and Surgical Research between 2000-2013. In this period of time several new subjects and courses have been introduced. The thematics have been widened, and the educational topics underwent a significant change and development: new teaching videos, revised note-books and a new textbook have been prepared through these years. Further, new training models (surgical training models, phantom and biomodels) have also been evolved. The educational activity of the Department was supported significantly several times (financial, contribution, grants) from the University of Debrecen, partner companies, HEFOP and TÁMOP grants. Infrastructural development in conjunction with the above increased the quality of educational standards in gradual and postgradual education, too. All these changes and developments were presented on various professional meetings and published in relevant journals, as part ofinternal quality control.

[Data on liver enzyme and histological changes caused by intermittent clampings of the hepatoduodenal ligament in an experimental model]

Intermittent compression of the structures of the hepatoduodenal ligament, is often performed during liver surgery. As a result, changes in hepatic blood supply and consequent reperfusion induced tissue damages will develop. Ischemia-reperfusion injury, which occur in local and distant regions, influence outcome of hepatic surgery, and it is in close correlation with the duration of hypoxia during the intervention. In animal model the effect of Baron/Pringle manoeuvre was investigated in terms of changes in liver function tests and histology. The study was carried out on 12 Beagle dogs, clamping of the hepatoduodenal ligament for 3×15 minutes then half an hour reperfusion was performed followed by blood and tissue sampling. Significant histological changes were observed both in the liver as well as the small intestine. In terms of liver function changes, GPT elevation occurred the earliest, GOT and LDH were also increased at the end of the 30 minutes reperfusion. In this animal model, the third 15 minutes compression turned out to be too long. Elevation in GPT levels was the most sensitive marker.

Autonomic dysfunction and circadian blood pressure variations in people with impaired glucose tolerance

AIMS

To assess circadian blood pressure variability in people with impaired glucose tolerance and a healthy control population.

METHODS

Seventy-five people with impaired glucose tolerance and 40 healthy volunteers (frequency matched on 10-year age bands and sex) underwent a detailed neurological assessment. Autonomic neuropathy was detected by the five standard cardiovascular autonomic tests and heart rate variability was characterized by the triangle index. Diurnal indices were assessed by 24-h ambulatory blood pressure monitoring. Systolic and diastolic diurnal indices were defined as: (mean daytime blood pressure - mean night-time blood pressure) × 100/mean daytime blood pressure.

RESULTS

Mean 24-h systolic and diastolic blood pressure was significantly higher in the group with impaired glucose tolerance compared with the control group [126 ± 12 (mean ± SD) vs. 117 ± 10, 75 ± 7 vs. 71 ± 6 mmHg, both P < 0.05). Systolic and diastolic diurnal indices and heart rate variability triangular index were significantly lower in people with impaired glucose tolerance compared with control subjects (9.1 ± 7.8 vs. 13.2 ± 5.4, 14.5 ± 9.7 vs. 18.4 ± 7.1 mmHg, 28.0 ± 8.4 vs. 39.5 ± 9.3, all P < 0.05). Differences in mean diastolic blood pressure, heart rate variability triangular index and the frequency of non-dippers between those with impaired glucose tolerance and control subjects seemed to be independent of BMI and the presence of cardiovascular autonomic neuropathy, as simultaneous adjustment for BMI and cardiovascular autonomic neuropathy had no major effect on the results.

CONCLUSION

Our data suggest that people with impaired glucose tolerance have increased diastolic blood pressure and abnormal circadian blood pressure regulation, independent of obesity and the presence of cardiovascular autonomic neuropathy.

Endothelin-1 and cerebral blood flow in a porcine model

The purpose of the study was to investigate whether provoked changes of cerebral perfusion pressure and arterial carbon dioxide tension are able to influence the cerebral metabolism of endothelin-1 (ET-1) in a porcine model. Brain tissue oxygen tension, regional cerebral blood flow and mean arterial blood pressure were monitored in 10 healthy pigs during induced hyperventilation (HV), hypertension (HrT) and hypotension (HoT). ET-1 was determined in the arterial and cerebrovenous blood. Microdialysis samples (lactate, glucose and pyruvate) were taken from brain and subcutaneous tissue. A significant decrease (p<0.05) of the arterial ET-1 (1.46+/-0.33 fmol/mL) compared to the baseline (2.18+/-0.36 fmol/mL) was observed after the HoT-period. We detected a positive correlation between cerebrovenous ET-1 and extracellular cerebral glucose (0.68; p<0.05) after the baseline as well as a negative correlation of -0.81 (p<0.005) between the cerebrovenous ET-1 level and the extracellular cerebral lactate after the HoT-period. These data imply that with increasingly pathological changes of the cerebral metabolism endothelin becomes progressively more important in the regulation of cerebral vascular tone.

[Conceptions about microsurgical education. What were 5,460 hours of microsurgical basic education enough for?]

Microsurgical education has an involuting role in the respects both of the effective clinical and successful research work. In Hungarian literature little number of paper can be found that deal with microsurgical educational methods, their results and efficacy. In our department for several decades we have taught the basics of microsurgery at different education levels (graduate and postgraduate), giving the possibility for practicing and developing as well. In this paper we summarize our educational objective and subjective experiences of more than 10 years and 5460 education hours in microsurgical basic courses. Besides the numeric summaries it became clear that the teacher's or tutor's and the candidates' experience and their ability to attain the basics of microsurgery are very important. According to our experience the most effective method is the education in small groups: one tutor and 2-3 candidates can reach the final goal, the basic microsurgical skill.

Hydrostatic characteristics of the ileocolic valve and intussuscepted nipple valves: an animal model

The ileocolic valve, in the dog, decelerates the passage of stools and prevents fecal reflux. A loss of anterograde resistance worsens the symptoms of short bowel syndrome. The absence of fecal reflux control enhances the risk of recurrence of Crohn's disease. The aim of the present study was to examine what length of intussusception-like nipple valve (INV) should be constructed in order to restore the hydrostatic characteristics of the normal ileocecal valve. The anterograde and retrograde hydrostatic resistances of INVs of different lengths (4, 5, 6, or 7 cm) were compared with those of the normal ileocolic valve by using a contrast enema and x-ray monitoring in a canine model. It was found that the 4-cm-long INV may be sufficient to achieve an appropriate antireflux efficacy (59.60 +/- 4.26 cm H(2)O) versus the ileocolic valve (25.80 +/- 4.92 cm H(2)O), but this does not furnish an anterograde resistance comparable to that of the normal ileocolic valve (10.70 +/- 1.15 cm H(2)O vs. 21.60 +/- 3.96 cm H(2)O). We found that the appropriate length of the INV with which the anterograde resistance of the ileocolic valve could be attained in our model was between 6 and 7 cm. Thus, the shortest possible constructed INV should be effective in clinical conditions such as Crohn's disease, but the recommended length in short bowel syndrome should be greater than this.

[Experimental "functional amputate model" in ischemia-reperfusion]

Limb amputation and ischemia-reperfusion (I/R) after trauma is a serious challenge, though there are few laboratory parameters that are available to predict the prognosis. It is even less so when possible adverse effects of preventive cooling may also influence the clinical outcome. We performed an experimental model earlier on mongrel dogs to investigate the local and systemic effects of cooled and non-cooled limb I/R. In this paper we describe the model and summarize the informative laboratory results. In the warm I/R group the femoral vessels were separately clamped for 3 hours, while steel-loop tourniquet for 7 hours was performed under the femoral vessels around the thigh. After ischemia releasing the clamps provided reperfusion for 4 hours then the steel-loop was removed. In the cooled I/R group similar procedure was performed but with cooling by ice bags. Cooled and non-cooled sham-operated groups also were used. Before operations, during the reperfusion and for 5 days blood samples were collected then haematology and chemistry parameters were determined. Blood rheology and certain coagulation factors were significantly different between the cool and non-cool ischemia-reperfusion groups, furthermore, the changes were also significant compared to sham-operated animals, suggesting that these parameters may be useful in the prognosis.

[The importance of hemorheological examinations in experimental limb ischemia-reperfusion injuries]

Rheological properties of the blood are determined by several factors and if they change it may be diagnostic for many diseases. It is well-known that during ischemia and reperfusion different free-radical liberating pathways are inducted besides the local physical and metabolical changes. These processes may harm red blood cells by increasing their rigidity and impairing their deformability. In ischemia-reperfusion models measurements of erythrocyte deformability is important. Characteristic alterations were observed in both rat and dog hind limb ischemia-reperfusion with vascular clamping on femoral vessels for 1 or 3 hours. Erythrocyte deformability was significantly impaired on the postoperative 1st-3rd days. The acute limb ischemia-reperfusion experimental models seem suitable for further in vivo rheological studies.

[Kidney neovascularization by the greater omentum after pretreatment with omental angiogenic factor]

BACKGROUND

Several diseases may affect the renal artery and the circulation of the kidney. In these cases alternative blood flow should be secured to preserve renal function. There are experimental methods for this, such as omentonephropexy. In this model the new vessels grow into the kidney from the omentum.

METHODS

Thirty mongrel dogs were anaesthetized and operated on. The left kidney was exposed, partially decapsulated, then omental angiogenic factor extractum was placed on the renal surface and the greater omentum was fixed there. After 4 weeks the left renal artery was ligated, and further 4 weeks later the right kidney was removed. Hematology tests were performed, urea, creatinine levels were measured and urine samples were tested after each operations. For statistical analysis Mann-Whitney rank sum and Wilcoxon signed rank tests were used.

RESULTS

The survival rate was 20%. Significant elevations were observed in serum creatinine and urea levels after each operation, mostly after the third one and in non-surviving animals. Moderate anaemia was also present.

CONCLUSION

The efficacy of the neovascularization presented in this study and the survival rate indicate further investigations are necessary in order to explore the mechanism and the dynamics of the vascularization processes.

[Can the injured spleen be preserved? Results of 20-year experiments]

Researches of different spleen salvaging techniques have begun in 1986 at our department. The early purpose was to develop new spleen preservation surgical techniques, such as spleen autotransplantation and spleen resection. Besides the morphological and radiological examinations we also performed different investigations including hemorheological, hemostaseological and immunological follow-up of the splenic function. From these parameters changes in red blood cell deformability and peripheral phagocyte activity could indicate the possible complications originated from the reduced splenic function. Recent paper takes a survey of these experiences.

[Teaching of microsurgery--in service of research and clinical practice]

We analyse the improving role of teaching microsurgery, the advantages of the microsurgical models in research and clinical practice. We summarize our experience in teaching basic microsurgery according to Furka's model in the last 15 years. The main characteristics of the principles are: activity, synchronism, video assistance, self-control, individualization, analysis. We show the curriculum of the courses for researchers and participants in graduate and postgraduate education, which consists dry-training on models followed by surgical interventions on rats. Summarizing of our practices: to learn the basic microsurgical techniques the participants need endurance, patience, and have to work hard. Effectiveness of the education is most successful if we organize small groups, if one teacher deals with a maximum of two or three candidates.

[Intraoperative laser doppler flowmetry of the tissue microcirculation of extraperitoneal transplanted omental flaps on dogs]

The aim of this study was to develop a new method to check of the viability of an extraabdominally transplanted omental flap. We performed free omental transplantation to the left lateral neck region in the frame of a formerly published new esophageal resection series on 5 dogs. Intraoperative laser Doppler flowmetry was performed, before and after isolation, after transplantation, and 14 days after the operation. From the 5 transplanted flaps, 4 survived the transplantation. The flap microcirculation deteriorated immediately after the transplantation, but at the time of re-operation the measurements showed similar microcirculation as control tissues, which proves the viability of the transplanted flaps. In our opinion, in dogs for the intraoperative monitoring of viability and microcirculation of free transplanted omental flaps, laser Doppler flowmetry is a feasible method.

[Determination of urinary NAG to detect renal ischemia-reperfusion injury and the protective effect of Allopurinol]

We analysed the effect of ischemia-reperfusion injury to renal parenchyma after unilateral renal artery clamping using urinary N-acetyl-beta-D-glucosaminidase (NAG) that is a sensitive parameter of early renal tubular injury. In the study 60 mongrel dogs were divided into 3 groups: in the 1st group the left renal artery was clamped for 45 minutes, in the 2nd group Allopurinol was administered before the clamping, the 3rd was the control group, where only laparotomy and closure of the abdomen was performed. Urinary NAG activity referring to urinary creatinine (NAG index) was determined before the operation, at the beginning of the reperfusion, in the 60th and 120th minute of the reperfusion then 1, 2, 3 and 5 days after the operation. The highest NAG indices relating to injury of the proximal tubuli were found at the beginning of the reperfusion, in the 60th and 120th minutes of the reperfusion, then NAG returned to preoperative level in each group. Significantly higher NAG indices were found in the ischemia-reperfusion group compared to the group with Allopurinol pretreatment. Renal ischemia-reperfusion injury and the protective effect of Allopurinol could be detected by lysosomal NAG enzyme. The injury of the tubular function was reversible so it could be a change in tubular function.

[Measurement of microcirculation during experimental ureter implantation]

INTRODUCTION

Various types of ureter neoimplantation methods can be used in diseases that affect the distal part of the ureter. The most common techniques are the Cohen and the Politano. When the ureter is dilatated tapering of the enlarged ureter is necessary during neoimplantation using excisional or plication techniques. The aim of the study was to compare the effect of these different methods on the ureter tissue microcirculation in animal model and to answer the question which technique has better outcome.

METHOD

The authors investigated tissue microcirculation patterns of ureter segments under surgical conditions employing Laser Doppler flowmetry in dogs. Different surgical procedures were compared in the function of tissue microcirculation as measured in the affected ureter segments. Measurements both in the intra- and postoperative periods were performed to compare different methods of ureter neoimplantation (Cohen vs. Politano-Leadbetter) and tapering (excisional technique, i.e. tailoring vs. plication of the lower ureter). The status of the ureter microcirculation was compared before and after catheterisation. 9 cases of Politano-Leadbetter and 9 cases of Cohen procedure as well as ureter tailoring in 7 and plication in 6 cases were performed in mongrel dogs. The microcirculation patterns of the ureter were detected intraoperatively and postoperatively using Laser Doppler Flowmetry device. The influence of catheter insertion on ureter microcirculation was examined in each case.

RESULTS

Among the neoimplantation methods the Cohen procedure whereas among the tapering procedures the plication of the ureter were found to affect the least the microcirculation of the ureter tissue. The catheter insertion had significantly worsened the blood supply.

CONCLUSION

Based on these results better outcome can be expected with the Cohen neoimplantation method and plication of ureter as compared with others.