Regulation of postnatal intestinal maturation by growth hormone: studies in rats with isolated growth hormone deficiency.

During the 3rd wk of postnatal life in the rat, dramatic maturational changes occur in the structure and function of the small intestine, enabling the animal to make the transition from milk to solid food. To investigate the role of GH in the regulation of this complex process, we studied postnatal intestinal maturation in the spontaneous dwarf rat, a strain of Sprague-Dawley rats with an autosomal recessive mutation in the GH gene resulting in complete but isolated GH deficiency. GH-deficient and GH-normal littermates were studied at d 7 and 14 (suckling) and d 23 (postweaned). The body weight of GH-deficient animals was inhibited by 60% at each age. Longitudinal growth of the small intestine was not inhibited, suggesting that longitudinal small bowel growth is independent of GH regulation. Mucosal cell mass was significantly lower in GH deficiency at all ages studied, and digestive hydrolase capacity per cm of intestine was significantly lower in GH-deficient postweaned animals. However, epithelial cell mass increased markedly in association with weaning and the maturation of lactase, sucrase, and aminooligopeptidase proceeded normally in GH deficiency. These data suggest that, although GH is not required for normal postnatal intestinal maturation, the mucosal epithelial hypoplasia found in GH-deficient animals suggests that GH or GH-dependent factors act as an intestinal mucosal growth factor whose function is to promote the homeostatic or steady-state regulation of mucosal epithelial growth.

Dupuytren's contracture: MR imaging findings and correlation between MR signal intensity and cellularity of lesions.

OBJECTIVE: Dupuytren's contracture is a common fibrosing disorder of the hand which often results in progressive and debilitating flexion contractures of the fingers. Recurrence after surgical release is common and may be related, in part, to the cellularity of the lesion. We describe the MR appearance of Dupuytren's contracture and correlate signal characteristics with the degree of cellularity of the lesion. SUBJECTS AND METHODS: A total of 11 hands in 10 patients were studied. All patients had surgical resection after MR imaging (median interval, 3 days). The surgical and pathologic findings were correlated with the MR findings. The signal characteristics of the lesions were correlated with the histologic findings. RESULTS: We found that MR imaging was accurate for detecting Dupuytren's contracture and depicting its extent. The lesions include subcutaneous nodules, usually at the level of the distal palmar crease, and cords that lie parallel and superficial to the flexor tendons. The cords had a uniformly low signal intensity (similar to the signal intensity of tendon) on both T1- and T2-weighted images in 18 of 22 cases, whereas the remaining four cases had a low to intermediate signal intensity on T1-weighted images (a slightly higher signal intensity than that of tendon) and a low signal intensity on T2-weighted images. Histologically, the cords were hypocellular and composed of dense collagen. Most nodules had an intermediate signal intensity (similar to that of muscle) on both T1- and T2-weighted images (10 of 13 cases), usually stippled with focal areas of lower signal intensity. Histologically, these nodules were mostly cellular. Three of the nodules had a low signal intensity on both T1- and T2-weighted images and were hypocellular histologically. CONCLUSION: We conclude that MR imaging can be used to define palmar involvement in Dupuytren's contracture. The signal characteristics of the lesions correlate with the degree of cellularity of the lesions as seen histologically. The ability to assess preoperatively the cellularity of lesions of Dupuytren's contractures may be of prognostic significance, because highly cellular lesions tend to have higher rates of recurrence after surgery than do hypocellular lesions.