Effectiveness of premedication with pronase for improving visibility during gastroendoscopy: a randomized controlled trial

BACKGROUND

Minute early gastric cancers can be removed with endoscopic mucosal resection techniques. However, early detection of these minute cancers with endoscopy is still difficult. For this purpose, use of a dye is helpful. To increase visibility further, gastric mucus should be removed before endoscopic examination. In this study, the effectiveness of premedication with pronase for improving visibility during gastroendoscopy was investigated.

METHODS

From January through July 1996, outpatients scheduled for gastroendoscopy were randomly assigned to oral premedication with the antifoam agent dimethylpolysiloxane alone (n=34), with dimethylpolysiloxane plus sodium bicarbonate (n=32), or with dimethylpolysiloxane, sodium bicarbonate, and pronase (n=34). All were given about 10 minutes before the start of endoscopy. After inserting the endoscope, the endoscopist gave visibility scores at conventional endoscopy and after methylene blue spraying.

RESULTS

Premedication with pronase significantly improved visibility before and after methylene blue spraying as compared with the two other groups pretreated without pronase. Pronase also significantly shortened the times for chromoendoscopic examination. Pronase had no significant effect on the culture of Helicobacter pylori.

CONCLUSION

Premedication with pronase improved endoscopic visualization during conventional endoscopy and chromoendoscopy. Its routine use at gastroendoscopy is therefore recommended.

Intravenous midazolam as a sedative for colonoscopy: a randomized, double-blind clinical trial

METHODS

Forty patients, aged between 36 and 60 years, scheduled to undergo colonoscopic removal of colorectal polyps were randomly assigned to receive 0.9% saline solution (n = 20) or 0.05 mg/kg body weight of midazolam (n = 20) intravenously.

RESULTS

Midazolam significantly (P < 0.001) increased the tolerance of patients to colonoscopy. It had no significant effect on pulse or systolic blood pressure during endoscopy. Arterial oxygen saturation decreased significantly (P < 0.01) during endoscopy in patients pre-treated with midazolam, but it did not decrease by more than 5%.

CONCLUSIONS

Intravenous midazolam is useful as a sedative for colonoscopy, but we recommend continuous oxygen saturation monitoring during endoscopy.

Involvement of uptake2 mechanism in inactivation of noradrenaline released by tyramine under anoxic conditions in perfused rat heart

Effects of uptake2 inhibition by corticosterone on tyramine-induced noradrenaline (NA) overflow under control, glucose-deprivation, anoxia and anoxia with glucose-deprivation were examined in perfused rat heart. Uptake2 inhibition by corticosterone (100 microM) had no effect on the NA overflow under control and glucose-deprivation, but significantly augmented the NA overflow by about 40% and 25% under anoxia and anoxia with glucose-deprivation, respectively. These results indicate that the uptake mechanism is at least in part responsible for the inactivation of NA under anoxic conditions in the perfused rat heart.

Effects of anoxia and ischemia on uptake2 of catecholamines in perfused rat heart

The effects of 30 min periods of either anoxia or ischemia (stop-flow) on the uptake2 of isoprenaline and on the production of O-methyl-isoprenaline, a major metabolite of isoprenaline formed by catechol-O-methyltransferase (COMT), were examined in the perfused rat heart. After either glucose deprivation or anoxia, the uptake2 of isoprenaline in hearts subsequently perfused with isoprenaline and 3',4'-dihydroxy-2-methyl-propiophenone, a COMT inhibitor, was similar to control values. However, uptake2 was decreased following either anoxia in association with glucose deprivation or ischemia. In the absence of the COMT inhibitor, neither glucose deprivation nor anoxia alone had any effect on the production of [3H]3-O-methyl-isoprenaline from [3H]isoprenaline, but both anoxia together with glucose deprivation and stop-flow ischemia decreased it. These findings indicate that both anoxia coupled with glucose deprivation and ischemia inhibit both uptake2 and COMT activity and suggest that such inhibition may be responsible for the high concentration of catecholamines released locally following myocardial infarction.

Impairment of the extraneuronal O-methylating system of isoproterenol by stop-flow ischemia in the perfused rat heart

Effects of ischemia on the extraneuronal O-methylating system were investigated in the perfused rat heart. Ischemia was produced by stopping of the perfusion for 30 min. Isoproterenol (ISO) was used as a model substrate for the extraneuronal uptake of catecholamines. The accumulation of ISO when catechol-O-methyltransferase (COMT) (EC 2.1.1.6) was inhibited by 3',4'-dihydroxy-2-methylpropiophenone (U-0521) was decreased by ischemia to about 50% of the control value. Ischemia decreased the formation of 3-O-methyl-ISO, a major metabolite of ISO formed by COMT, to about 30% of that in the control hearts. The efflux of extraneuronally accumulated ISO in the heart with and without ischemia was measured. The diffusion constant calculated by the slope of the efflux rate of ISO or by the efflux rate divided by the amount of ISO remaining in the heart after ischemia was about 50% of the control. The experiments showed that ischemia suppressed the extraneuronal O-methylating system (extraneuronal uptake, COMT and diffusional flux) in the rat heart. Such suppression may lead to higher concentrations of local catecholamines in myocardial infarction.