Reduced Messenger RNA Expression of the Neuronal Nitric Oxide Synthase Gene in Infantile Hypertrophic Pyloric Stenosis

PURPOSE: Nitric oxide synthesized by neuronal nitric oxide synthase (nNOS) has been described as a mediator of smooth muscle relaxation in the mammalian gastrointestinal tract. Impaired expression of the nNOS gene is suggested in the development of infantile hypertrophic pyloric stenosis (IHPS). We examined the expression of nNOS mRNA in pyloric muscle biopsy specimens obtained from 8 patients with IHPS and attempted to correlate the results with the clinical characteristics. METHODS: The expression of nNOS mRNA in pyloric muscle biopsy specimens for 8 patients with IHPS was examined using a reverse transcription- polymerase chain reaction (RT-PCR) technique. For the control, a smooth muscle layer specimen of a neonate with a normal pylorus was used. RESULTS: In the control specimen, the level of nNOS mRNA expression was 48.4% of beta-actin mRNA. In the two thinnest (each 3 mm) of pyloric muscle thicknesses as determined by ultra-sonography, the expressed nNOS mRNA were 16.7% and 30.3%. The two thickest (each 8.3 mm) expressed as 35.3% and 22.9% nNOS. The two samples from the earliest age of symptomatic onset (1 day, 7 days after birth) expressed as 25.6% and 4.8%. The two from the latest age of onset (each 30 days) expressed as 7.4% and 10.5%. The control specimen revealed a higher level of nNOS mRNA expression than those of the IHPS specimens. There was no significant correlation between the clinical characteristics and the levels of nNOS mRNA in the IHPS specimens. CONCLUSION: Since a low level of nNOS mRNA expression may lead to impaired production of NO, our observations indicate that the hypertrophic pyloric muscle of an IHPS patient may be the result of a reduced expression of the nNOS gene at the mRNA level. In IHPS patients, there was no correlation between the clinical characteristics and the levels of expressed nNOS mRNA.

Assessment of flavin-containing monooxygenase (FMO) activity by determining urinary ratio of theobromine and caffeine in a Korean population after drinking a cup of coffee

To examine individual variation in drug metabolism catalyzed by flavin-containing monooxygenase (FMO), 179 Korean volunteers' urinary molar concentration ratio of theobromine (TB) and caffeine (CA) was determined. Their urine was collected for 1 hr (between 4 and 5 hrs) after they drank a cup of coffee containing 115 mg CA and analyzed by an HPLC system. The lowest TB/CA ratio obtained was 0.40, the highest ratio was 15.17 (38-fold difference), and the median ratio for all subjects was 1.87. The mean was 2.66 with 2.36 S.D.. In 134 nonsmokers, the mean ratio was 2.35 +/- 1.93, that of 51 males was 2.30 +/- 2.26 and 83 females was 2.37 +/- 1.85, respectively. There was no significant gender difference in the obtained TB/CA ratio (Mann-Whitney test; p=0.518). There were no smokers among the 83 female volunteers. In the remaining 96 male subjects, the ratio obtained in 51 nonsmokers was 2.30 +/- 2.06 and that of 45 smokers was 3.62 +/- 3.19. This indicated that the TB/CA ratio was increased significantly in smokers (p=0.007). However, when the TB/CA ratios (FMO activity) obtained in all 179 Korean volunteers are compared with the urinary concentration ratios of paraxanthine (PX) plus 1,7-dimethylurate (17U) to CA (CYP1A2 activity), there was a weak but significant correlation (Pearson's correlation coefficient test; r2=0.28, p<0.0001). This indicates that, although the urinary TB/CA ratio mostly represents FMO activity, minor contribution by CYP1A2 activity cannot be ignored. In conclusion, the FMO activity measured by taking the urinary TB/CA ratio from normal healthy Korean volunteers shows marked individual variations without significant gender differences and the increased TB/CA ratio observed in cigarette smokers may have been caused by the increased CYP1A2 activity.

Ethanol prevents from acetaminophen inducible hepatic necrosis by inhibiting its metabolic activation in mice

Concomitant administration of a single acute dose of ethanol (4 g/kg) protected mice from the hepatocellular injury observed upon administration of a large dose of acetaminophen (400 mg/kg). This was evidenced by the normal histological appearances of liver sections and by the lowered serum aminotransferase activities in mice treated with ethanol and acetaminophen together. In the mice treated with acetaminophen alone, along with the hepatic necrosis, the hepatic microsomal aminopyrine N-demethylase activity was decreased. However, co-administration of ethanol prevented this acetaminophen dependent inhibition on the microsomal mixed function oxidase activity. Pharmacokinetic studies indicated that the concentration of un-metabolized drug in the blood was increased in the ethanol treated mice. Furthermore, upon co-administration of ethanol, although the biliary levels of acetaminophen metabolites (glucuronide, sulfate and cysteine conjugates) were decreased, the level of unmetabolized acetaminophen was increased. Our findings suggest that co-administration of an acute dose of ethanol reduces the degree of hepatocellular necrosis produced by a large dose of acetaminophen and this ethanol dependent protection is, in major part, afforded by suppression of the hepatic microsomal mixed function oxidase activity catalyzing the metabolic activation of acetaminophen.