Oxidative stress seems to be a cardinal feature of cholestasis, implicated in the pathophysiology of organ injury not only in the liver, but also in several extrahepatic tissues. The present study was designed to assess directly oxidative stress in vital organs of experimentally jaundiced rats by measuring the key oxidative stress marker superoxide radical (O2(*-)). Twelve male Wistar rats underwent laparotomy and were divided into two groups - group I (n = 6) sham operated, and group II (n = 6) bile-duct ligated. Ten days later, the O2(*-) formation rate was quantified in liver, intestine, kidney and heart of all animals. These measurements were done by application of a new ultrasensitive fluorescent assay for the in vivo quantification of O2(*-), which is based on the 1:1 molar stoichiometric reaction of O2(*-) with dihydroethidine (DHE, an O2(*-) trap) that results in the formation of the specific product 2-OH-ethidium. 2-OH-Ethidium was measured by fluorescence in rats' organs and its formation rate was converted to O2(*-) production rate. As compared to sham-operated rats, in jaundiced rats there was a significant increase of O2(*-) in the intestine (136%, P < 0.01), liver (104%, P < 0.01), and kidney (95%, P < 0.01), whereas there was no significant difference in heart O2(*-) levels. Superoxide radical may play an important role in the pathophysiology of cholestatic liver injury, intestinal barrier failure and renal failure, associated with postoperative morbidity and mortality in obstructive jaundice. On the contrary, O2(*-) and oxidative stress are possibly not implicated in the pathophysiology of hepatic cardiomyopathy.

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Study design: Cervical spondylotic myelopathy (CSM) represents the most commonly acquired cause of spinal cord dysfunction among individuals over 55 years old. The pathophysiology of the disease involves static and dynamic mechanical factors, which are the result of chronic degeneration. The clinical course of the disease remains unpredictable. In the past, many experimental animal models have been developed to study the cellular and molecular mechanisms underlining the pathophysiology of the disease. Objectives: To create a new animal model of CSM, which will reproduce the temporal course of the disease and the local microenvironment at the site of spinal cord compression. Methods: We performed posterior laminectomy to New Zealand rabbits at the level of C7, and a thin sheet (5-7 mm) of aromatic polyether was implanted with microsurgical technique at the epidural space underneath C5-C6 laminae. Motor function evaluation was performed after the operation and once a week thereafter. Results: After 20 weeks, the animals were killed, and the histological evaluation of spinal cord at the site of compression above and below it, using eosin hematoxylin, immonohistochemistry and KluverBarrera techniques reveals axonal swelling and demyelination, interstitial edema and myelin sheet fragmentation. Moreover, histological evaluation of C5 and C6 laminae reveals osteophyte formation. Conclusion: We believe that this CSM model reproduces the temporal evolution of the disease and creates a local microenvironment at the site of spinal cord compression, which shares the same characteristics with that of human disease.

The time-related alterations of superoxide radical measured in vivo by employing an ultrasensitive fluorescent assay in the liver, intestine, kidney and brain of rats with experimentally induced obstructive jaundice was investigated. Eighteen rats were randomly divided into Group A, rats subjected to sham operation, and Group B, rats subjected to bile duct ligation (BDL). Three rats from each group were subsequently killed at different time points post-operatively (1, 5 and 10 days). As compared to sham-operated, BDL rats showed a gradual increase with time of superoxide radical in the intestine, liver, kidney and brain: for animals sacrificed on the 1(st), 5(th) and 10(th) day the increase was 45%, 50% and 96% in the liver, 76%, 81% and 118% in the intestine, 64%, 71% and 110% in the kidney and 76%, 95% and 142% in the brain, respectively. This study provides direct evidence of an early appearance of oxidative stress in diverse organs, implying a uniform systemic response to biliary obstruction and emphasizing the need of early bile flow restoration.

The study aimed to directly measure in vivo superoxide radical (O*2) a direct indicator of oxidative stress, in the brain of rats with experimentally induced obstructive jaundice by employing a new quantitative ultrasensitive fluorescent assay requiring minimum sample. O*2 anion is specific for dihydroethidine (DHE) and upon reaction gives a characteristic product, namely 2-OH-ethidium. Ten male rats underwent laparotomy and were divided into two groups: I, sham operated and II bile duct ligation. Ten days later, following injection with DHE (a O*2 trap), all animals were killed and samples from cerebral cortex, midbrain and cerebellum were removed for analysis. It was shown that compared to group I, in group II the O*2 was increased by 67% in the cerebral cortex and by 37% in the midbrain as a consequence of experimental obstructive jaundice, while its levels were unaffected in the cerebellum. The data in this experimental obstructive jaundice model imply a region-specific increase of O*2 formation rate, being higher in cerebral cortex, less so in the midbrain and not at all in cerebellum.