Free radicals and antioxidant systems in reflux esophagitis and Barrett＇s esophagus

AIM: Experimental studies suggest that free radicals are involved in acid and pepsin-induced damage of esophageal mucosa. The profile and balance between free radicals and antioxidant systems in human esophagitis are unknown. METHODS: Superoxide anion and its powerful oxidant reaction with nitric oxide (peroxynitrite) generation were determined in esophageal mucosal biopsies from 101 patients with different gastro-esophageal reflux diseases and 28 controls. Activity of both superoxide dismutase (SOD) and catalase, and reduced glutathione (GSH) levels, were also assessed. Expression of Cu,ZnSOD, MnSOD and tyrosine-nitrated MnSOD were analyzed by Western blot and/or immunohistochemistry. RESULTS: The highest levels of superoxide anion generation were found in patients with severe lesions of esophagitis. Peroxynitrite generation was intense in Barrett's biopsies, weaker in esophagitis and absent/weak in normal mucosa. Expression of Cu,ZnSOD and MnSOD isoforms were present in normal mucosa and increased according to the severity of the lesion, reaching the highest level in Barrett's esophagus. However, SOD mucosal activity significantly decreased in patients with esophagitis and Barrett's esophagus, which was, at least in part, due to nitration of its tyrosine residues. Catalase activity and GSH levels were significantly increased in mucosal specimens from patients with esophagitis and/or Barrett's esophagus. CONCLUSION: A decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrite radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with gastroesophageal reflux. Administration of SOD may be a therapeutic target in the treatment of patients with esophagitis and Barrett's esophagus.     

Two homozygous mutations in the 11 beta-hydroxysteroid dehydrogenase type 2 gene in a case of apparent mineralocorticoid excess

The human microsomal 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta HSD2) metabolizes active cortisol into cortisone and protects the mineralocorticoid receptor from glucocorticoid occupancy. In a congenital deficiency of 11 beta-HSD2, the protective mechanism fails and cortisol gains inappropriate access to mineralocorticoid receptor, resulting in low-renin hypertension and hypokalemia. In the present study, we describe the clinical and molecular genetic characterization of a patient with a new mutation in the HSD11B2 gene. This is a 4-yr-old male with arterial hypertension. The plasma renin activity and serum aldosterone were undetectable in the presence of a high cortisol to cortisone ratio. PCR amplification and sequence analysis of HSD11B2 gene showed the homozygous mutation in exon 4 Asp223Asn (GAC-->AAC) and a single nucleotide substitution C-->T in intron 3. Using site-directed mutagenesis, we generated a mutant 11 beta HSD2 cDNA containing the Asp223Asn mutation. Wild-type and mutant cDNA was transfected into Chinese hamster ovary cells and enzymatic activities were measured using radiolabeled cortisol and thin-layer chromatography. The mRNA and 11 beta HSD2 protein were detected by RT-PCR and Western blot, respectively. Wild-type and mutant 11 beta HSD2 protein was expressed in Chinese hamster ovary cells, but the mutant enzyme had only 6% of wild-type activity. In silico 3D modeling showed that Asp223Asn changed the enzyme's surface electrostatic potential affecting the cofactor and substrate enzyme-binding capacity. The single substitution C-->T in intron 3 (IVS3 + 14 C-->T) have been previously reported that alters the normal splicing of pre-mRNA, given a nonfunctional protein. These findings may determine the full inactivation of this enzyme, explaining the biochemical profile and the early onset of hypertension seen in this patient.     

Long-duration stress

No extensive information exists in literature concerning the late or residual effects of stress on motility of small bowel and colon. Moreover, the duration and magnitude of the intestinal motor response to stress are still ignored. Therefore, the aim of our work was to determine, in rat, the effect of long-duration stress induced by restraint on the motility of small bowel and colon. Observations were made during physical restraint and 60 h later. Bipolar electrodes were implanted on the gastrointestinal serosa from the pylorus to the sigmoid colon in male Wistar rats. Electromyographic (EMG) recordings were made during fasting state, and a control EMG recording session was performed during 12 hr, followed by a 12-hr recording during restraint stress. After a 60-hr resting period, another EMG recording session was performed during 3 hr. During stress in the pylorus and small bowel, the recurrence of migrating myoelectrical complexes (MMCs) was immediately interrupted and replaced by a continuous and irregular activity. The motility index (number of spike bursts/10 min) was augmented rapidly on the jejunum and ileum, but it increased only gradually on the pylorus. Only on the transverse colon were the number of spike bursts/hour and their relative duration increased after 7 hr of physical restraint. In contrast, the sigmoid colon displayed a gradual decrease in the relative duration of contractile activity during the first 6–7 hr of stress. At 60 hr after stress in the pylorus and small bowel, a normal control motor activity was restored (MMC, motility index) on the jejunum and on the ileum, but the motility index on the pylorus was decreased. Throughout the colon, a faster motor activity as well as an increase in the number of spike bursts/hour was observed. In conclusion, a 12hr physical restraint stress induced instant drastic changes in small bowel motility, but a normal motility pattern was rapidly restored after the end of the stress period. However, on the colon, the motor changes are moderate at the beginning of the restraint period, then gradually increased with time, and were still largely persistent three days after the cessation of physical restraint.     

The use of transient elastometry for assessing liver fibrosis in patients with HIV and hepatitis C virus coinfection.

BACKGROUND: Transient elastometry (TE) is accurate for detecting significant liver fibrosis and cirrhosis in hepatitis C virus (HCV)-monoinfected patients. However, this procedure has been insufficiently validated in patients with human immunodeficiency virus (HIV) and HCV coinfection. The purpose of this study was to validate reported cutoff values of TE that discriminate significant liver fibrosis and cirrhosis in HIV-HCV-coinfected subjects. METHODS: Liver stiffness measurements were obtained for 169 HIV-HCV-coinfected adult patients who had undergone a liver biopsy or who had received a nonhistologic diagnosis of cirrhosis within 12 months before or after a liver stiffness measurement. Patients had received no prior therapy for HCV infection. RESULTS: TE measurements ranged from 3.6 kPa to 75 kPa. The area under the receiver operating characteristic curve was 0.87 (95% confidence interval, 0.84-0.93) for significant liver fibrosis and 0.95 (95% confidence interval, 0.92-0.99) for cirrhosis. To diagnose significant liver fibrosis, a cutoff value of 7.2 kPa was associated with a positive predictive value of 88% and a negative predictive value of 75%. Thirty-four patients (20%) were misclassified when this cutoff value was used. Thirteen (24%) of 54 patients with liver stiffness values <7.2 kPa had significant liver fibrosis detected by liver biopsy. To diagnose cirrhosis, a cutoff value of 14.6 kPa was associated with a positive predictive value of 86% and a negative predictive value of 94%. Thus, 13 patients (10%) had disease that was misclassified using this cutoff value. CONCLUSIONS: We found that the diagnostic accuracy of TE was high for detecting cirrhosis and good for diagnosis of significant liver fibrosis. However, the performance of TE was low for discriminating mild fibrosis from significant liver fibrosis, which might limit the applicability of this technique in clinical practice.     

Antioxidant Curcuma extracts decrease the blood lipid peroxide levels of human subjects

Extracts of the rhyzome of Curcuma longa are widely used as food additives in India and other Asiatic and Central American countries. Moreover, it has been recently shown that these extracts (“turmeric”), as well as “curcumin” and related phenolic compounds isolated from Curcuma, have a powerful lipid anti-oxidant action, when tested in in vitro systems. This justifies the present attempt to find out whether hydroalcoholic extracts of Curcuma longa also exert an antioxidant effect in human subjects. Our data show that a 45-day intake (by healthy individuals ranging in age from 27 to 67 years) of Curcuma hydroalcoholic extract (at a daily dose equivalent to 20 mg of curcumine) results in a significant decrease in the levels of serum lipid peroxides. These peroxides probably play an important pathogenic role in normal senescence and age-related diseases such as atherosclerosis. Therefore, hydroalcoholic extracts of Curcuma longa (that have very low toxicity and have been cleared as food additives in the above countries) may find use in future preventive geriatrics after further clinical studies.