Protective effects of heparin on hepatic ischemia and reperfusion lesions in rabbits

Magnetic Resonance Diffusion Tensor Imaging Characterize the Hepatic Ischemia-Reperfusion Injury in an Animal Study

BACKGROUND

Hepatic ischemia-reperfusion (I/R) injury is the main cause of morbidity and mortality after hepatectomy; thus, new methods for reducing I/R injury are required. The aim of this study is to evaluate changes in the average apparent diffusion coefficient (ADCavg) and fractional anisotropy (FA) in rabbits with partial hepatic I/R injury with magnetic resonance diffusion tensor imaging (DTI).

METHODS

The left lobe of the rabbit liver underwent 60 minutes of ischemia followed by 0.5, 2, 6, 12, 24, and 48 hours of reperfusion. T2-weighted images (T2WI), T1-weighted images (T1WI), DTI, and contrast-enhanced T1WI were performed; 6 b values were used for DTI on 6 diffusion directions. The serum levels of transaminases and liver histopathology findings were examined.

RESULTS

In the early stage of I/R (0.5 hour), ADCavg decreased significantly and increased sharply to 2 hours, then increased from 6 hours to 48 hours of reperfusion, except for a transient decrease (24 hours). Meanwhile, FA showed almost the opposite trend, drastically increasing during the first 0.5 hour and then slightly decreasing until 48 hours of reperfusion, except for an obvious decrease in the 2-hours group. The serum levels of liver markers and the pathologic scores were sharply increased in the I/R group after reperfusion and correlated with DTI of hepatic tissue after I/R.

CONCLUSIONS

Diffusion tensor imaging is feasible for imaging I/R-induced liver damage and can discriminate isotropic properties of the liver after I/R injury with objective changes in the ADCavg and FA. Diffusion tensor imaging can be a promising novel approach for use in clinical management after liver surgery.

The effects of verapamil and heparin co-administration on sperm parameters and oxidative stress in prevention of testicular torsion/detorsion damage in rats

In this research, the impacts of combined administration of verapamil and heparin on testicular torsion damage were examined. In this experimental study, 30 sexually mature male Wistar albino rats were divided into five equal groups haphazardly (n = 6): Group 1 was the sham group. In group 2, a 2-hr testicular torsion was induced, and thereafter, detorsion was done. Rats in group 3 and group 4 experienced an identical surgical procedure like group 2, but verapamil and heparin were administered in 0.3 mg/kg and 800 IU/kg doses respectively, and in group 5, a combination of verapamil and heparin were administered. Intraperitoneal drug injection in all treatment groups was done 30 min before testicular detorsion. Testicular torsion significantly changed sperm parameters, oxidative stress biomarkers and Cosentino's histological score compared to the sham group (p < .05). All treatment groups reduced testicular damage by decreasing oxidative stress and improving sperm parameters, but heparin and co-administration of verapamil and heparin were significantly better than verapamil injection alone. However, heparin injected group was more effective than other treatment groups (p < .05). Overall, an anticoagulant like heparin is more effective than a calcium channel blocker such as verapamil, and it is more likely to reduce testicular torsion injuries.

The effects of enoxaparin on the liver in experimental pneumoperitoneum model

PURPOSE:

To investigate the potential protective effects of enoxaparin against the adverse events of carbon dioxide (CO2) pneumoperitoneum.

METHODS:

Thirty four rats were divided into three groups: Group 1 (sham) underwent insertion of Veress needle into the abdomen and 90 min of anesthesia with no gas insufflation. The animals in control and enoxaparin groups were subjected to 90 min of 14 mmHg CO2 pneumoperitoneum. Enoxaparin (100 u/kg) was administered subcutaneously to the rats in enoxaparin group one hour before the operation. After 90 min of pneumoperitoneum, the rats were allowed for reperfusion through 60 min. Blood and liver samples were obtained for biochemical and histopathological examination.

RESULTS:

Treatment with enoxaparin decreased the histopathological abnormalities when compared with the control group. The highest levels of oxidative stress parameters were found in control group. The use of enoxaparin decreased the levels of all oxidative stress parameters, but the difference between the control and enoxaparin groups was not statistically significant.

CONCLUSION:

Enoxaparin ameliorated the harmful effects of high pressure CO2 pneumoperitoneum on the liver.

Circulating histones are major mediators of systemic inflammation and cellular injury in patients with acute liver failure

Acute liver failure (ALF) is a life-threatening systemic disorder. Here we investigated the impact of circulating histones, recently identified inflammatory mediators, on systemic inflammation and liver injury in murine models and patients with ALF. We analyzed histone levels in blood samples from 62 patients with ALF, 60 patients with chronic liver disease, and 30 healthy volunteers. We incubated patients' sera with human L02 hepatocytes and monocytic U937 cells to assess cellular damage and cytokine production. d-galactosamine plus lipopolysaccharide (GalN/LPS), concanavalin A (ConA), and acetaminophen (APAP) were given to C57BL/6N mice to induce liver injury, respectively, and the pathogenic role of circulating histones was studied. Besides, the protective effect of nonanticoagulant heparin, which can bind histones, was evaluated with in vivo and ex vivo investigations. We observed that circulating histones were significantly increased in patients with ALF, and correlated with disease severity and mortality. Significant systemic inflammation was also pronounced in ALF patients, which were associated with histone levels. ALF patients' sera induced significant L02 cell death and stimulated U937 cells to produce cytokines, which were abrogated by nonanticoagulant heparin. Furthermore, circulating histones were all released remarkably in GalN/LPS, ConA, and APAP-treated mice, and associated with high levels of inflammatory cytokines. Heparin reduced systemic inflammation and liver damage in mice, suggesting that it could interfere with histone-associated liver injury. Collectively, these findings demonstrate that circulating histones are critical mediators of systemic inflammation and cellular damage in ALF, which may be potentially translatable for clinical use.

Trisulfate Disaccharide Decreases Calcium Overload and Protects Liver Injury Secondary to Liver Ischemia/Reperfusion

Background

Ischemia and reperfusion (I/R) causes tissue damage and intracellular calcium levels are a factor of cell death. Sodium calcium exchanger (NCX) regulates calcium extrusion and Trisulfated Disaccharide (TD) acts on NCX decreasing intracellular calcium through the inhibition of the exchange inhibitory peptide (XIP).

Objectives

The aims of this research are to evaluate TD effects in liver injury secondary to I/R in animals and in vitro action on cytosolic calcium of hepatocytes cultures under calcium overload.

Methods

Wistar rats submitted to partial liver ischemia were divided in groups: Control: (n = 10): surgical manipulation with no liver ischemia; Saline: (n = 15): rats receiving IV saline before reperfusion; and TD: (n = 15): rats receiving IV TD before reperfusion. Four hours after reperfusion, serum levels of AST, ALT, TNF-α, IL-6, and IL-10 were measured. Liver tissue samples were collected for mitochondrial function and malondialdehyde (MDA) content. Pulmonary vascular permeability and histologic parameters of liver were determined. TD effect on cytosolic calcium was evaluated in BRL3A hepatic rat cell cultures stimulated by thapsigargin pre and after treatment with TD.

Results

AST, ALT, cytokines, liver MDA, mitochondrial dysfunction and hepatic histologic injury scores were less in TD group when compared to Saline Group (p<0.05) with no differences in pulmonary vascular permeability. In culture cells, TD diminished the intracellular calcium raise and prevented the calcium increase pre and after treatment with thapsigargin, respectively.

Conclusion

TD decreases liver cell damage, preserves mitochondrial function and increases hepatic tolerance to I/R injury by calcium extrusion in Ca2+ overload situations.

Protective role of methylprednisolone and heparin in ischaemic-reperfusion injury of the rat testicle

This study evaluated the therapeutic efficacy of heparin and methylprednisolone in the treatment of ischaemic reperfusion (IR) injury of the testis. Twenty-four male Sprague-Dawley rats were allocated equally into three groups of eight animals each. The left testes were rotated 720° for 2 h in the rats in the torsion-detorsion group. Rats in the treatment groups underwent the same surgical procedure as the torsion-detorsion group but were also given methylprednisolone (group II) or heparin (group III) by an intraperitoneal route 30 min prior to detorsion. Left orchiectomy was performed in all rats from each experimental animal at 2 h after detorsion, and the tissue was harvested for the measurement of malondialdehyde (MDA), protein carbonyl (PC) and nitric oxide (NO) and the endogenous antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase. Additional tissue was evaluated using histopathological and immunohistochemical changes. PC and MDA levels were significantly reduced in the treated groups compared to the control group. There was no statistically significant difference in NO level or SOD, GSH-Px and catalase activity among the treatment groups. Histopathological and immunohistochemical findings supported biochemical changes. It is concluded that pre-treatment with methylprednisolone or heparin protects the testis in ischaemic reperfusion injury caused by testicular torsion-detorsion.

Modulation of Thrombosis Significantly Reduces Testicular Damage after Testicular Torsion in Rats: Anti-Thrombotic Treatment and Testicular Torsion

OBJECTIVE

To evaluate the effects of thrombolysis and/or anticoagulation on testicular viability after testicular tortion (TT) was the aim of this study. It has been suggested that alterations of circulation during TT result in thrombus formation that might prevent sufficient perfusion after detorsion. Due to the narrow safety margin of testicular perfusion, even moderate disturbances in blood supply can cause major testicular damage.

METHODS

In 112 rats, the right testicle was torsed for 3 or 6 hours. After detorsion and randomization, they received either enoxaparin, alteplase, both, or placebo, according to their subgroup. Thrombus formation was accessed via D-dimers, pDNA, oxidative testicular damage was evaluated via glutathione peroxidase and malondialdehyde, and cellular damage via inhibin B, testosterone, histological analysis (Johnsen score, Cosetino grading), and TUNEL assay.

RESULTS

One hundred and twelve rats were included in the study. The treatment with alteplase or enoxaparin showed significantly less testicular damage and significantly improved Sertoli cell function. Enoxaparin significantly reduced oxidative impairment.

CONCLUSION

The results of the study indicate that TT induces thrombus formation and demonstrate that modulation of thrombosis significantly ameliorates testicular damage in rats. Hence, this treatment option after TT ought to be evaluated in humans.

Dexmedetomidine: a review of applications for cardiac surgery during perioperative period

Cardiac surgery is associated with a high incidence of cardiovascular and other complications during the perioperative period that translate into increased mortality and prolonged hospital stays. Safe comprehensive perioperative management is required to eliminate these adverse events. Dexmedetomidine is a selective α2-adrenoreceptor agonist that has been described as an ideal medication in the perioperative period of cardiac surgery. The major clinical effects of dexmedetomidine in this perioperative period can be summarized as attenuating the hemodynamic response, cardioprotective effects, antiarrhythmic effects, sedation in the ICU setting, treatment of delirium, and procedural sedation. Although there are some side effects of dexmedetomidine, it is emerging as an effective therapeutic agent in the management of a wide range of clinical conditions with an efficacious, safe profile. The present review serves as an overview update in the diverse applications of dexmedetomidine for cardiac surgery during the perioperative period.

Study of heparin in intestinal ischemia and reperfusion in rats: morphologic and functional evaluation

To study whether treatment with heparin (HEP) attenuates intestinal dysfunction caused by ischemia (I) and reperfusion (R), rats were treated with HEP (100 U/kg intravenously) or saline solution (SS) before I (60 min), which was produced by occlusion of the superior mesenteric artery, and R (120 min). After I or I/R, we mounted 2-cm jejunal segment in an organ bath to study neurogenic contractions stimulated by electrical pulses or KCl, using a digital recording system. Thin jejunal slices were stained with hematoxylin and eosin for optical microscopy. Compared with the sham group, jejunal contractions were similar in the I + HEP and the I/R + HEP groups, but reduced in the I + SS and the I/R + SS groups. The jejunal enteric nerves were damaged in the I + SS and the I/R + SS, but not in the I + HEP and the I/R + HEP cohorts. These results suggested that HEP attenuated intestinal dysfunction caused by I and I/R.

Adverse effects of heparin

All the adverse effects of heparins are related to their wide variety of biological activities, with bleeding being the most important safety issue, resulting directly from the potency of heparin as an anticoagulant. However, it is hard to define the bleeding risk, since it depends on numerous parameters including the indication, dosage, method, and duration of heparin application, the clinical study design and definition of bleeding as well as patient characteristics and determinants of bleeding such as type of surgery and co-medication. Nonbleeding complications of heparins are caused by binding of heparin molecules to proteins other than antithrombin and to cells, which is generally more pronounced with unfractionated heparin than with low-molecular-weight heparins. Accordingly, heparin-induced thrombocytopenia, the most severe nonbleeding adverse reaction, occurs about 10 times less with low-molecular-weight heparins than with unfractionated heparin. Frequent and therefore important adverse reactions of heparins are skin lesions resulting from delayed-type hypersensitivity reactions. All the other undesirable effects are discussed as well, but they are mostly clinically irrelevant.

Perfusion computed tomography evaluation of partial hepatic ischemia reperfusion in a rabbit model

RATIONALE AND OBJECTIVES

An animal model of partial hepatic ischemia/reperfusion injury (I/R) has benefits for decision making and clinical management after liver transplantation or massive hepatic resection. The aim of this study was to evaluate the change in perfusion parameters after partial hepatic I/R in rabbits using multislice computed tomography perfusion imaging.

MATERIALS AND METHODS

Thirty rabbits underwent 60 minutes of left hepatic lobar ischemia followed by 0.5, 2, 6, 12, and 24 hours of reperfusion (six rabbits were used for each reperfusion interval). An additional six rabbits served as sham-operated controls. The perfusion indices of hepatic arterial perfusion, hepatic portal perfusion, total liver perfusion, and hepatic perfusion index were measured. Levels of serum aspartate transaminase and alanine transaminase and liver histopathology at different time points were also examined.

RESULTS

Hepatic microvascular flow patterns showed heterogeneity in the 6-hour, 12-hour, and 24-hour groups. Computed tomographic perfusion parameters were significantly different between infarcted liver tissue and viable liver tissue. In poorly enhancing tissues in the 6-hour, 12-hour, and 24-hour groups, hepatic portal perfusion and total liver perfusion were lower compared to the sham group, but hepatic arterial perfusion of poorly enhancing tissues significantly increased in the 6-hour group and then decreased slightly from 12 to 24 hours after reperfusion. The hepatic perfusion index was always higher compared to that of the sham group. Hepatic arterial perfusion, hepatic portal perfusion, total liver perfusion, and hepatic perfusion index in the noninfarcted areas decreased slowly from 6 to 24 hours after reperfusion. The levels of alanine transaminase and aspartate transaminase in the I/R groups significantly increased after reperfusion and were correlated with the computed tomographic perfusion indices of infarcted liver tissue.

CONCLUSIONS

Computed tomographic perfusion can dynamically monitor the pathologic processes of liver I/R and reveal the underlying microvascular disorder, improving clinical management after liver surgery.