Distinct pattern of ret oncogene rearrangements in morphological variants of radiation-induced and sporadic thyroid papillary carcinomas in children

In this study, we compare the morphological and genetic characteristics of 38 post-Chernobyl thyroid papillary carcinomas from Belarussian children 5-18 years old with those of 23 sporadic papillary carcinomas from the same age children without history of radiation exposure from Los Angeles and Cincinnati. Among radiation-induced tumors, solid variant of papillary carcinoma was found in 37%, follicular in 29%, typical papillary in 18%, and mixed and diffuse sclerosing variants in 8% each. In the sporadic group, a typical papillary pattern was prevalent in 70%, follicular in 17%, diffuse sclerosing variant in 9%, and solid in 4%. In both groups, the prevalence of ret rearrangements was high, but the frequency of specific types of rearrangement was significantly different. Among radiation-induced tumors, ret/PTC3 was found in 58%, ret/PTC1 in 16%, and ret/PTC2 in 3%, whereas among sporadic tumors, ret/PTC1 was found in 47% (P < 0.05), and ret/PTC3 was found in 18% (P = 0.01). The morphological variants of papillary carcinoma showed different prevalence of the specific types of ret rearrangement. Seventy-nine % of solid variant tumors had ret/PTC3, whereas only 7% had ret/PTC1 (P = 0.0007). Among typical papillary tumors, ret/PTC1 was found in 38%, ret/PTC3 in 19%, and ret/PTC2 in 5%. Thus, ret rearrangements are highly prevalent in pediatric papillary carcinomas from children exposed to radiation and in those occurring sporadically. However, the types of ret/PTC vary between these two populations, with ret/PTC3 present more commonly in post-Chernobyl tumors. Furthermore, solid variants have a high prevalence of ret/PTC3, whereas typical papillary carcinomas do not, suggesting that the different types of ret rearrangement confer neoplastic thyroid cells with distinct phenotypic properties.

Small intestinal absorption during endotoxemia in swine

We studied the effects of systemic endotoxemia on small intestinal absorption in an in vivo animal model. Seven adolescent Yorkshire swine underwent creation of 25 cm distal ileal Thiry-Vella fistulae. After 1 week recovery, the fistulae were perfused with a solution of glucose and electrolytes labeled with 14C-PEG, and net absorption of water, Na+, Cl-, and glucose was calculated. Animals were studied under three different conditions: (1) Basal fasting state, (2) immediately after intravenous injection of E. coli lipopolysaccharide (LPS; 250 micrograms/kg), and (3) 24 hours after LPS. Water, Na+, and Cl- absorption was significantly reduced 2 hours after LPS, but recovered to baseline values by the third hour after LPS. Twenty-four hours after LPS water, Na+, and Cl- absorption was significantly decreased below baseline values. Glucose absorption after LPS paralleled that of water and electrolytes, except that the transient early recovery was not observed. Histological studies of the ileum after LPS showed marked epithelial inflammation at 6 hours, villous atrophy at 24 hours, and signs of recovery at 7 days. Intestinal absorption of water, electrolytes, and glucose is adversely affected in the immediate and early periods after an endotoxemic episode, but the histological epithelial injury secondary to endotoxemia is reversible.