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Biomedical subjects

I Marzi

Publications and source records attributed to I Marzi.

At least 19 recordsLinked to original sources
PubMed1999

Antioxidative resuscitation solution prevents leukocyte adhesion in the liver after hemorrhagic shock.

BACKGROUND: The generation of iron-dependent toxic oxygen radicals during the initial resuscitation from hemorrhagic shock was shown to be a relevant factor for the initiation of the inflammatory cascade. Therefore, this experimental study was designed to evaluate the effects of a deferoxamine-conjugated hydroxyethyl-starch solution (HES-DFO) on oxygen radical induced injury and microcirculatory alterations in the rat liver compared with resuscitation with regular hydroxyethyl-starch, lactated Ringer's solution (RL), or a gelatin-based solution. METHODS: After hemorrhage and random assignment to 1 hour of blood-free resuscitation with the aforementioned solutions, hepatic microcirculation and leukocyte adhesion characteristics were assessed by intravital fluorescence microscopy in anesthetized rats. Oxygen radical activity was estimated by determination of glutathione levels in liver homogenate and determination of thiobarbituric acid-reactive substances in plasma as markers of lipid peroxidation. RESULTS: Resuscitation by HES-DFO resulted in restoration of hemodynamic parameters compared with gelatin-based solution and HES. The hepatic microcirculation was severely altered 1 hour after resuscitation from shock in all groups indicated by sinusoidal narrowing and reduced sinusoidal blood flow. HES-DFO, however, attenuated leukocyte adhesion and improved velocity index in sinusoids as well as sinusoidal perfusion. The shock-associated generation of oxygen radicals during resuscitation was prevented by HES-DFO as indicated by restored glutathione and reduced thiobarbituric acid-reactive substances. CONCLUSION: The results suggest that HES-DFO effectively reduces oxygen radical formation during the initial resuscitation period, thus, attenuating pathologically enhanced leukocyte adhesion and improving hepatic microcirculation.

Animals↗
PubMed1998

Mediators in polytrauma--pathophysiological significance and clinical relevance.

Multiple trauma induces an inflammatory response syndrome of the whole body that is triggered by (a) hemorrhage inducing an ischemia/reperfusion (I/R) syndrome and (b) fractures or organ contusions inducing tissue-repair processes. I/R injury generates oxyradical/proteolytic metabolites and adhesion molecules, while tissue and endothelial injury directly stimulate complement, coagulation and kinin pathways. Membrane-derived phospholipase A2 and lipid mediators potentiate cellular interactions and increase microvascular permeability. The tissue-repair process mediates macrophage/monocyte and T-cell activation which releases pro- and anti-inflammatory cytokines. Mediator action follows a "three-level model", proposing that depending on the degree of traumatic injury cellular and humoral responses may spread from a cellular to an organ and then a systemic level. The systemic response can result in a severe immunological dys-homeostasis that potentially hazards the survival of the trauma patient by uncontrollable cellular dysfunction, appearing clinically as multiple organ-dysfunction syndrome. Blood-mediator concentrations often parallel the inflammatory process; initially, high levels of cytokines are followed by severe organ dysfunction. However, interpretation of these data remains difficult due to distinct beneficial or detrimental effects of mediators on the different levels of inflammation and missing prognostic threshold values, indicating a risk of adverse effects. Future studies must determine pro- and anti-inflammatory mediators directly, during the intensive care therapy, and evaluate their clinical relevance prospectively for the different levels of inflammation at local and systemic sites.

Humans↗
PubMed1998

Modern therapy of chronic wounds with respect to radiation.

BACKGROUND: Descriptions of wound care techniques have been found in some of the oldest archeological findings and chronic wounds have been threaded man thousands of years. However, only in the last few decades substantial progress has been made in understanding the cellular and biochemical processes relevant in normal healing. PATHOPHYSIOLOGY: Wound healing is a complex process involving a variety of different cells, proteins, chemoattractants, proteinases and growth factors. The normal repair process is a coordinated cellular and biochemical event and can be characterized by 3 different healing phases (inflammatory, proliferative, and remodeling phase). Certain pathophysiologic conditions and metabolic disorders alter this preprogrammed course, leading to delayed healing or chronic non-healing wounds. DISTURBANCE OF WOUND HEALING AFTER RADIATION: Especially irradiation can complicate tissue repair and surgical wound healing. Therefore this article will review the basic understanding of the wound healing process and the knowledge of modern surgical and conservative wound therapy from a surgical point of view, which is essential to surpass pathophysiological situations and avoid chronic wounds.

Chronic Disease↗
PubMed1997

[Deferoxamine-conjugated hydroxyethyl starch reduces reperfusion injury to the liver following hemorrhagic shock].

UNLABELLED: Deferoxamine is known to reduce the iron-dependent generation of toxic oxygen-derived radicals during reperfusion of ischaemic tissue. The present study investigates the antioxidative properties of a deferoxamine-conjugated hydroxyethyl starch solution and its effects on the hepatic microcirculation in a haemorrhagic-shock rat model. METHODS: Anaesthetized Sprague-Dawley rats were tracheotomized, prepared for invasive haemodynamic monitoring, and subject to haemorrhagic shock (MAP = 40 mmHg during 60 min). The animals were resuscitated blood-free with lactated Ringer's (RILA, n = 10), gelatin (GELA, n = 10), hydroxyethyl starch (HES, n = 10), or deferoxamine-conjugated HES (DFO, n = 8) solution (MAP > or = 70 mmHg). After 1 h of resuscitation the hepatic microcirculation was investigated by intravital microscopy, the glutathione concentration was measured in liver homogenate, and the thiobarbituric acid reactive substances (TBARS) were determined as markers of lipid peroxidation. RESULTS: Resuscitation resulted in restoration of MAP to > or = 70 mmHg within a short time. The volume required to stabilise the arterial pressure during 1 h of resuscitation was significantly less in the DFO group compared with HES, GELA, and RILA. Significantly higher glutathione levels in liver homogenate as well as decreased TBARS levels were observed in the DFO group. The shock-induced increase of leukocyte adhesion in liver sinusoids was significantly attenuated by DFO. CONCLUSION: DFO significantly attenuates shock-induced oxidative stress, thereby reducing the early inflammatory reaction and improving the hepatic microcirculation.

Animals↗
PubMed1997

Role of nitric oxide in the regulation of the hepatic microcirculation in vivo.

BACKGROUND/AIMS: Nitric oxide (NO) is an important mediator in the regulation of vascular tone. However, no data exist on the physiological role of NO in the regulation of the hepatic microcirculation. This study was designed to evaluate the role of NO in the hepatic microcirculation in vivo under physiological conditions. METHODS: The hepatic microcirculation was investigated in anesthetized rats by intravital fluorescence microscopy after injection of fluorescein-isothiocyanate-labeled erythrocytes. Following assessment of baseline sinusoidal perfusion, animals were randomly treated with L-NMMA (n=6), L-arginine (n=6), nitroprusside sodium (NPS, n=5) or a comparable volume of NaCl (n=4). Drugs were given through a portal vein catheter at three doses (Dx), each followed by intravital microscopy. L-NMMA was given: 5 mg/kg (D1), 25 mg/kg (D2), 50 mg/kg (D3); L-arginine 30 mg/kg (D1), 150 mg/kg (D2), 300 mg/kg (D3); and NPS continuously 80 microg x kg(-1) x h(-1). RESULTS: L-NMMA induced a significant increase of mean arterial blood pressure (MAP) (114 vs. 129 mm Hg; p<0.05). In contrast, MAP of NPS-treated animals decreased (107 vs. 91 mm Hg; p<0.01) whereas MAP of animals receiving L-arginine did not significantly differ. Sinusoidal blood flow revealed dose-dependent changes: L-NMMA significantly decreased perfusion of sinusoids (D1: 65%, D2: 57%, D3: 50% of baseline, p<0.05). Injection of L-arginine increased the sinusoidal flow even with the lowest dose (D1: 137%, D2: 133%, D3: 123%, p<0.05). Continuous infusion of NPS had little effect on sinusoidal blood flow at the first and second times of microscopy but sinusoidal blood flow was significantly increased at the third time (D1: 103%, D2: 106%, D3: 122%). CONCLUSIONS: Inhibition of NOS results in a dose-dependent disturbance of the hepatic microcirculation despite significantly increased MAP, whereas L-arginine increases the sinusoidal blood flow. The results indicate an important role for NO in the regulatory mechanisms of hepatic sinusoidal perfusion under physiological conditions.

Animals↗
PubMed1997

Recombinant N-terminal fragment of bactericidal/permeability increasing protein (rBPI21) prevents shock-induced microcirculatory alterations in the liver.

OBJECTIVE: To investigate the effects of the recombinant 21-kilodalton N-terminal fragment of recombinant bactericidal and permeability increasing protein (rBPI21) on leukocyte adhesion and the hepatic microcirculation after hemorrhagic shock. DESIGN: Prospective, randomized, blinded, and placebo-controlled experimental study. SETTING: University research laboratory. SUBJECTS: Anesthetized Sprague-Dawley rats, weighing 220 to 250 g. INTERVENTIONS: Rats were subjected to 60 mins of hemorrhagic shock and subsequent resuscitation to sufficiently restore systemic circulation. The microcirculation of the liver was investigated by intravital fluorescence microscopy 5 hrs after hemorrhagic shock. Four shock groups were compared with a sham-control group. Shock groups received either rBPI21 (10 mg/kg) or placebo either before or after shock period. MEASUREMENTS AND MAIN RESULTS: No differences were observed in hemodynamic, respiratory, or metabolic parameters between the shock groups. However, the hepatic microcirculation showed severe deterioration 5 hrs after shock, indicated by significantly narrowed sinusoids in all shock groups compared with controls (8.5 +/- 0.3 microm vs. 10.0 +/- 0.4 pm). Leukocyte adhesion was markedly increased to comparable values in both placebo groups (619 cells/mm2 and 644 cells/mm2; sham, 168 cells/mm2). Neutralization of endotoxin by administration of rBPI21 before or after shock resulted in plain reduction of pathologic leukocyte-endothelial interaction (138 cells/mm2 and 85 cells/mm2). CONCLUSION: The results support the hypothesis that endotoxin induces microcirculatory alterations after shock, and further suggest a potentially beneficial role of rBPI21 in the treatment of posttraumatic endotoxin-induced inflammatory reactions.

Animals↗
PubMed1997

Adenosine kinase inhibitor GP515 attenuates hepatic leukocyte adhesion after hemorrhagic hypotension.

Adhesion of leukocytes to the vascular endothelium hallmarks a key event in neutrophil-mediated organ injury after ischemia-reperfusion. The autacoid adenosine has been shown to inhibit activated neutrophil function and to interfere with leukocyte-endothelial adherence. Its therapeutic use in ischemia-reperfusion, however, has been limited by severe cardiovascular side effects. We therefore investigated the effects of the adenosine kinase inhibitor GP515 in vivo on hepatic leukocyte-endothelial interactions in a rat model of hemorrhagic hypotension and resuscitation, using intravital microscopy. Rats were pretreated with either GP515 (0.25 mg/kg) or saline in a randomized and blinded manner and subjected to pressure-controlled hemorrhagic hypotension at a mean arterial pressure of 40 mmHg for 60 min followed by 5 h of resuscitation. Five hours after resuscitation in saline-treated animals, firm leukocyte-sinusoidal adhesion was strongly enhanced in the periportal and midzonal sublobular regions, and sinusoidal diameters were also markedly reduced. Compared with saline treatment, GP515 significantly attenuated shock and resuscitation-induced leukocyte adhesion in both sublobular regions. Moreover, although GP515 did not significantly affect macrohemodynamical and hematological parameters, it enlarged narrowed sinusoidal diameters and tended to improve sinusoidal blood flow. We propose that the adenosine-regulating agent GP515 has a therapeutic potential to attenuate ischemia-reperfusion-induced inflammation by capitalizing on the beneficial anti-inflammatory effects of endogenous adenosine.

Adenosine Kinase↗
PubMed1997

Significance of TNF in hemorrhage-related hemodynamic alterations, organ injury, and mortality in rats.

To evaluate the role of tumor necrosis factor-alpha (TNF-alpha) in hemodynamic alterations, multiple organ damage, and mortality caused by hemorrhagic shock, we employed a monoclonal antibody to TNF-alpha (TNF-alpha MAb) in anesthetized rats subjected to prolonged hemorrhagic shock (mean arterial pressure of 30-35 mmHg for 180 min) followed by resuscitation over 50 min. Treatment of rats with 20.0 mg/kg TNF-alpha MAb 15 min after the end of resuscitation significantly decreased the total peripheral resistance index (P = 0.031) and provided remarkable protection from multiple organ damage compared with controls. The 48-h survival rate was significantly higher in the treatment group (73.3%) than in the control group (26.7%; P = 0.029). The results suggest that TNF-alpha induced by hemorrhagic shock in rats is an important mediator of pathophysiological alterations associated with cardiovascular abnormalities, multiple organ injury, and even lethality. Postresuscitation treatment with TNF-alpha MAb, even after an initial TNF-alpha formation had occurred, significantly attenuated the cardiovascular consequences and improved the survival rate. Thus monoclonal antibodies to TNF-alpha might provide new prospects in the treatment of hemorrhage-related disorders.

Animals↗
PubMed1996

Platelet-activating factor is involved in the regulation of pathological leukocyte adhesion after liver transplantation.

An increased leukocyte adhesion and loss of integrity of endothelial cells is known to be a critical step in the reperfusion period after cold ischemia of transplanted livers. Platelet-activating factor (PAF) is discussed as one of the inflammatory mediators involved in mediating reperfusion injury, e.g., by regulation of leukocyte adhesion. In this study we investigated the effect of a synthetic PAF receptor antagonist, WEB 2086 (Boehringer Ingelheim, FRG), on microcirculation and adhesion of leukocytes to sinusoidal endothelium after liver transplantation in the rat. Livers from SPRD rats (n = 6 per group) were stored for 5 hr in ice-cold UW solution and orthotopically transplanted using the cuff technique. In a randomized and blinded fashion WEB 2086 (1 mg/kg body wt) or placebo was given twice intravenously, at the beginning of the recipient operation and 1 min prior to reperfusion of the liver graft. After in vivo staining of leukocytes with acridine orange, microcirculation and leukocyte-endothelium interaction of transplanted livers and livers from sham-operated animals were investigated 90 min and 5 hr after surgery by means of intravital microscopy. After 90 min of reperfusion, temporary leukocyte adhesion in periportal regions was increased after liver transplantation (22.0 +/- 2.5%; mean +/- SEM) in contrast to the sham group (14.2 +/- 1.8%). Administration of WEB 2086 reduced temporary leukocyte adhesion significantly (11.5 +/- 2.5%; P < 0.05), whereas no significant differences were observed with respect to permanent leukocyte adhesion. Five hours after recipient operation, a significant increase of permanent leukocyte adhesion was observed after transplantation (21.0 +/- 2.6%; P < 0.05) compared to sham-operated animals (12.1 +/- 1.7%). Application of WEB 2086 diminished permanent leukocyte adhesion significantly (12.2 +/- 1.3%; P < 0.05), whereas no differences were noticed between the different groups with respect to temporary leukocyte adhesion at this time. The results indicate that reduction of temporary leukocyte adhesion in the early reperfusion period by administration of PAF receptor antagonist WEB 2086 was followed by a reduction of permanent leukocyte adhesion in the late reperfusion period, e.g., at 5 hr. Thus, it is concluded that PAF is one of the mediators which is involved in the regulation of leukocyte adhesion after liver transplantation.

Animals↗
PubMed1996

The influence of resuscitation on hemodynamics and oxygen radical-induced reperfusion injury after arterialized liver transplantation in the rat.

Extended hemodynamic monitoring during arterialized rat liver transplantation procedure and the effects of resuscitation with albumin, starch-desferrioxamine-conjugated hydroxyethyl starch (HES-DFO), or hydroxyethyl starch (HES) on hemodynamics are presented. Livers from SPRD rats were stored for 20 hr in ice-cold UW solution and were orthotopically transplanted with reconstruction of the hepatic artery under hemodynamical monitoring applying invasive measurement of mean arterial blood pressure (MAP) and cardiac output (CO). Comparable amounts of albumin, HES-DFO, and HES were given in a randomized and blinded fashion after transplantation. Ringer's solution was given additionally when blood pressure was below 65 mmHg. Fifteen, 60, and 90 min after surgical procedure blood samples were taken to determine acid base status, blood gases, and blood cell count. Oxygen radical-induced reperfusion injury was determined by thiobarbituric acid reactive substances (TBARS) in serum and total glutathione in liver tissue 90 min after surgery. During the anhepatic period CO was reduced to 20% of baseline and MAP to 40 mmHg. In all groups, declamping led to a transient recovery of hemodynamic situation, whereas during further reperfusion, CO and MAP were significantly reduced in the HES- and HES-DFO-treated group in contrast to the group receiving albumin. Animals of the HES group required significantly more Ringer's solution to maintain blood pressure (2.6 +/- 0.9 ml; 4 of 6 animals needed additional resuscitation) than animals given albumin (0.4 +/- 0.3 ml, P < 0.05, 2/9 needed further supplementation) or HES-DFO (1.2 +/- 0.5 ml; 5/10 required additional resuscitation), respectively. Animals treated with HES or HES-DFO failed to restore base excess and serum lactate in contrast to resuscitation with albumin. However, TBARS was mitigated by resuscitation with HES-DFO compared to albumin and HES, whereas no significant differences were observed in respect to tissue glutathione of transplanted livers. In conclusion the model described allows intensive monitoring of hemodynamic parameters and metabolic status during arterialized rat liver transplantation procedure. Moreover, the results indicate that resuscitation with albumin could maintain central hemodynamics and restore homeostasis during the early reperfusion period after transplantation in contrast to resuscitation with HES or HES-DFO, respectively. Although resuscitation with HES-DFO resulted in mitigation of lipid peroxides determined by TBARS, no significant improvement of hemodynamics and homeostasis could be observed during reperfusion as it can be observed with albumin.

Animals↗
PubMed1996

Attenuation of shock-induced inflammation in the rat liver depends on the time of TNF-alpha inhibition.

The relevance of tumor necrosis factor-alpha (TNF-alpha) inducing early inflammatory reactions in the liver after hemorrhagic shock, for example, leukocyte adhesion, has been well described. This study evaluated the anti-inflammatory effects of a monoclonal antibody against TNF-alpha (TN3.19.12) in terms of the time of application, namely, prior to shock induction, at the time of resuscitation, and after resuscitation. The hepatic microcirculation was investigated by intravital fluorescence microscopy in female Sprague-Dawley rats undergoing severe hemorrhagic shock for 60 min and subsequent resuscitation. TN3.19.12 or placebo was given in a randomized and blinded manner either 60 min prior to shock induction, 1 min prior to resuscitation, or 15 min after the onset of resuscitation. The number of firmly adherent leukocytes in the livers of treated animals depended on the time of application of TN3.19.12. Leukocyte adhesion was significantly reduced when TN3.19.12 was given prior to shock induction or at the time of resuscitation and was less effective when administered after the onset of resuscitation. The results further confirm that TNF-alpha initiates very early pathological leukocyte adhesion in the liver 5 h following shock. Inhibition of leukocyte adhesion after shock, however, depends strongly on the time of TNF-alpha blocking. While TN3.19.12 prior to shock induction resulted in most effective attenuation, only very early treatment allowed limitation of posttraumatically increased leukocyte adhesion.

Animals↗
PubMed1996

Influence of pentoxifylline and albifylline on liver microcirculation and leukocyte adhesion after hemorrhagic shock in the rat.

The aim of this study was to evaluate the effects of two xanthine derivates, pentoxifylline (PTX) and its more metabolically stable analogue, albifylline (HWA 138), on hepatic sinusoidal perfusion and leukocyte endothelial interactions in the liver after hemorrhagic shock. Sprague-Dawley rats (n = 8 per group) were exposed to hemorrhagic shock at 40 mm Hg for 60 minutes and subsequently resuscitated with 60% of shed blood and lactated Ringer's solution before intravital microscopy of the liver 3 hours after resuscitation. Using fluorescence markers, quantitative evaluations of red blood cell (RBC) and white blood cell (WBC) velocities and WBC endothelium interactions were performed. Animals were chosen randomly and blindly to receive either PTX or HWA 138 in a dosage of 25 mg/kg body weight 1 minute before resuscitation, or they received placebo. This was followed by a further infusion of 25 mg/kg body weight during the 3-hour resuscitation period. Although systemic parameters were comparable in all groups, both xanthine derivates enhanced the reduced velocity of RBCs and WBCs of the placebo group. Pathological values of WBC endothelium adhesion in the placebo group (adhesion index: 126.7 +/- 19.5 s/100 WBCs, mean +/- SE) was significantly reduced by PTX (64.4 +/- 10.5, p < 0.05) and HWA 138 (71.9 +/- 10.7, p < 0.05). The results indicate a significant reduction of shock-induced leukocyte adhesions to the sinusoidal endothelium in the liver. In addition, both xanthine derivates led to improved microvascular blood flow in the liver. Thus, PTX and HWA 138 reveal multiple positive effects on early shock-induced alterations in the liver, supporting earlier studies which indicated their potential application in shock therapy.

Animals↗
PubMed1996

[Pathophysiology of polytrauma].

Sequential organ failure after multiple trauma emerges from a whole-body inflammatory process which develops as a complex host defense response to hypovolemic shock/resuscitation and traumatic tissue injury. Successful prevention and treatment involves exact assessment of inflicted damage and profound knowledge of the different stages of posttraumatic immune alterations. Local release of potent inflammatory mediators (cytokines, complement, arachidonic acid derivatives, reactive oxygen metabolites) primarily induces a repair process. However, massive soft tissue and bone injury, follow-up surgery, infections and blood transfusions trigger a systemic spill over of these mediators orchestrating a generalized inflammatory response (Systemic Inflammatory Response Syndrome, SIRS). Diffuse capillary leakage and microcirculatory disorder prepare cellular dysfunction. Secondary severe immune defects support septic complications which maintain an autodestructive process. Therapeutical advances depend on the analysis of local and time-dependent expression of relevant inflammatory mediators and cellular signalling systems.

Arachidonic Acid↗
PubMed1996

[Shock room management of polytrauma].

The emergency room functions as a junction between preclinical and early clinical treatment of patients with multiple trauma and should have defined technical and room possibilities. The personal staff should continue resuscitation measures and perform clinical and technical diagnostic procedures according to trained algorithms. The recognition of life-threatening injuries, the set up of correct priorities and application of respective surgical procedures characterize a good emergency room management.

Algorithms↗