Oral sodium phosphate versus sulfate-free polyethylene glycol electrolyte lavage solution in outpatient preparation for colonoscopy: a prospective comparison.

BACKGROUND: Biochemical abnormalities induced by oral sodium phosphate and the risk of cardiac arrhythmias as potential sequelae have yet to be investigated. METHODS: We studied 98 outpatients scheduled to undergo diagnostic colonoscopy and prospectively randomized them to receive oral sodium phosphate or sulfate-free polyethylene glycol electrolyte lavage solution (SF-PEG-ELS) as recommended by the manufacturers. RESULTS: Forty-nine patients received sodium phosphate and 49 received SF-PEG-ELS. There was no significant difference in tolerance or quality of preparation as judged by blinded endoscopists. Significant changes in serum sodium, potassium, chloride, calcium, ionized calcium, and inorganic phosphorus levels were noted following sodium phosphate preparation when compared to values before preparation. A significantly greater number of patients who received sodium phosphate preparation had serum potassium and ionized calcium levels that fell into the abnormal range. Ambulatory electrocardiogram monitors placed 24 hours before the preparation and removed after colonoscopy showed no increase in ventricular premature contractions or other serious arrhythmias in either group during preparation or colonoscopy. CONCLUSIONS: (1) Sodium phosphate and SF-PEG-ELS are equally well tolerated and effective in preparation for outpatient colonoscopy, and (2) sodium phosphate preparation at the recommended dose causes significant alterations in serum sodium, potassium, chloride, calcium, ionized calcium, and phosphorus levels.

The rate of proliferation among African trypanosomes is a stable trait that is directly related to virulence.

The relationship between the growth rate of Trypanosoma brucei gambiense and its virulence was investigated. A cloned, monomorphic, slow growing, and relatively avirulent line of T. b. gambiense was serially passaged at 3- to 5-day intervals through immunosuppressed mice. The growth rate measured within the first 2 patent days of infection did not vary significantly through the first 25 passages but by passage 50 had decreased significantly from 11.9 +/- 1.1 hr to 9.0 +/- 0.7 hr. A clone from passage 50 and three different second peak heterologous variants all had statistically similar growth rates, indicating that the rate of proliferation was a stable trait. With the faster rate of proliferation there was a corresponding increase in virulence. The inoculum necessary to kill 50% of normal outbred mice in the first peak of parasitemia (LD50) dropped significantly from 3 X 10(6) first passage parasites to 4 X 10(5) passage 50 parasites. The lethal load for both fast and slow growing organisms was the same (greater than 2 X 10(9) trypanosomes/ml of blood). To further link virulence and growth rate, a strong correlation (r = 0.89) was measured when generation times of 10 closely related lines of T. b. gambiense, and 2 lines of pleomorphic T. b. rhodesiense were compared to their LD50 values. While the rate of trypanosomal proliferation was similar between the day of inoculation through the second patent day, it slowed to 64% of that level once parasitemias exceeded 3 X 10(8) organisms/ml of host blood.(ABSTRACT TRUNCATED AT 250 WORDS)