A novel 5-lipoxygenase inhibitor prevents gallstone formation in a lithogenic prairie dog model.

Gallstone formation is dependent on biliary cholesterol supersaturation, the pronucleating effects of gallbladder mucin, and inflammation. We evaluated the effect of aspirin (ASA) and a 5-Lipoxygenase inhibitor (FLAPI) on cholesterol precipitation and leukotriene levels in an animal model of cholesterol gallstone formation. Male prairie dogs were divided into four dietary groups: normal chow controls, 1.2 per cent cholesterol (XOL), 1.2 per cent cholesterol plus ASA (XOL + ASA, 100 mg/kg/d), and cholesterol plus FLAPI (XOL + FLAPI, 100 mg/kg/12h). At 3 weeks the subjects were anesthetized, cholecystectomy performed, and the common duct cannulated for bile sampling. Cholesterol precipitation, lithogenic indices, and leukotriene content were analyzed. The group XOL + FLAPI did not form cholesterol crystals, whereas the group XOL + ASA did (P < 0.05, Fisher's exact test). All cholesterol-fed groups had significantly increased lithogenic indices when compared to controls. The XOL + FLAPI group showed a significant and paradoxical increase in LTB4 compared to the other groups (P < 0.05, ANOVA, Fisher's PLSD). This study has shown a significant decrease in the rate of cholesterol stone formation through the use of a novel leukotriene inhibitor at high doses, despite a high cholesterol diet.

The prognostic value of quantitative bone scan in knee osteochondritis dissecans. A preliminary experience.

We reviewed the records of 12 patients ages 9 to 16 years with knee osteochondritis dissecans. All patients had clinical histories and examinations, four radiographic views of the knee, and technetium-99m diphosphonate quantitative bone scans. Scan results (symmetric, increased, or decreased activity), clinical course, healing time, and final outcome were correlated to determine the prognostic value of the scan. We divided the patients into those with open physes (distal femoral and proximal tibial) and those with closed physes. Four of the six patients with open physes had increased activity on the bone scan. All four of these knees healed with nonsurgical treatment. The other two patients had decreased activity on bone scan, and both required surgical treatment after nonsurgical treatment failed. Of the six patients with closed physes, all had increased activity on the bone scan, but only two patients had healing of the osteochondral lesion without surgery. Quantitative bone scanning had a 100% predictive value for the prognosis in osteochondritis dissecans patients with open physes, but for those with closed physes the predictive value was less. Because the natural history in the adolescent group is less predictable, it is in this group that the quantitative scan would be most helpful. In this small group of patients, quantitative bone scanning had limited prognostic value.

Display of mitochondria in root tip cells.

A method for displaying mitochondria and proplastids in root tip sections of Tradescantia paludosa and cereals was modified from Altmann and Volkonsky. Root tips were fixed in 3% glutaraldehyde in phosphate buffer, pH 7.1, or acetate buffer, pH 4.8, for 3 hr, rinsed and postchromed overnight in 3% potassium dichromate, all at room temperature (20 C), dehydrated through a tertiary butanol series and embedded in ester wax. Four-micrometer sections were stained in hot acid fuchsin in aniline water, rinsed, treated with 1% sodium phosphomolybdate for 30 sec, rinsed and stained progressively with azure B for 3-10 min before being made permanent. Mitochondria and proplastids were stained brilliant crimson against a light blue cytoplasm with deep blue chromosomes. Previously reported difficulties with Altmann staining techniques are attributed to the erratic action of the classical fixatives used.

Abscisic acid deficiency prevents development of freezing tolerance in Arabidopsis thaliana (L.) Heynh.

Abscisic acid (ABA) has been implicated as a regulatory factor in plant cold acclimation. In the present work, the cold-acclimation properties of an ABA-deficient mutant (aba) of Arabidopsis thaliana (L.) Heynh. were analyzed. The mutant had apparently lost its capability to cold acclimate: the freezing tolerance of the mutant was not increased by low temperature treatment but stayed at the level of the nonacclimated wild type. The mutational defect could be complemented by the addition of exogenous ABA to the growth medium, restoring freezing tolerance close to the wild-type level. This suggests that ABA might have a central regulatory function in the development of freezing tolerance in plants. Cold acclimation has been previously correlated to the induction of a specific set of proteins that have been suggested to have a role in freezing tolerance. However, these proteins were also induced in the aba mutant by low temperature treatment.