Effects of continuous infusion of insulin-like growth factor I and II, alone and in combination with thyroxine or growth hormone, on the neonatal hypophysectomized rat.

In this study, we examined the effects of systemically administered insulin-like growth factor (IGF)-I and -II on growth of the hypophysectomized (Hx) neonatal rat. Neonatal Wistar rats were Hx or sham Hx on postnatal day (PND) 6 and implanted sc with Alzet pumps on PND 10. Recombinant human IGF-I or -II were infused between PND 10 and 18 at an average dose of 1.9 micrograms/g body weight (BW) per day. In addition, some groups received daily sc injections of recombinant human GH or thyroxine (T4) at 2.5 micrograms and 25 ng/g BW per day, respectively. Pups were sacrificed on PND 18 and serum IGF levels determined. Despite restoration of serum IGF-I levels to sham control values in the Hx pups infused with IGF-I, no significant increase in BW occurred, although some increase in individual organ growth was observed (spleen, kidney, lung). Similarly, administration of IGF-II proved ineffective as a growth promoter in the neonatal Hx rat. In contrast, GH alone stimulated BW gain (P less than 0.001). T4 proved most potent in increasing skeletal growth (50% increase over Hx controls, P less than 0.001), without increasing serum IGF-I or -II levels. IGF-I and GH were equally effective in promoting a small yet statistically significant (17% over Hx controls, P less than 0.05) increase in skeletal growth. A synergistic effect on BW was observed with combined administration of T4 plus IGF-I to the Hx pups (P less than 0.05). The effects of hormonal therapy on serum IGF binding proteins (IGFBPs) was assessed by Western ligand blots. Administration of IGF-I, but not GH, resulted in increased levels of IGFBP-3, the predominant IGFBP of the adult rat. We conclude that systemically administered IGFs in doses that result in normalization of serum levels are ineffective promoters of somatic growth in neonatal rats. While normalization of serum IGF-I levels does result in modest skeletal growth, selective organ growth and increased serum IGFBP-3, growth stimulation does not equal that seen with GH (body weight) or thyroid hormone (skeletal growth). Differences in IGFBP profiles fail to account for the increased potency of GH as a promoter of BW gain. Thus, our data do not support a major endocrine role for IGF-I or -II in neonatal growth, but are consistent with an autocrine/paracrine action of IGF in the mediation of neonatal mammalian growth.

Endovascular abdominal aortic aneurysm repair in 144 patients: correlation of aneurysm size, proximal aortic neck length, and procedure-related complications.

PURPOSE: During endovascular abdominal aortic aneurysm (AAA) repair, larger aneurysms often present formidable anatomic challenges to the insertion of the delivery catheter and graft deployment. The authors sought to evaluate whether large-diameter aneurysms and those with short proximal aortic necks might be associated with a higher frequency of insertion-related and short-term complications. MATERIALS AND METHODS: From October 1999 to August 2000, 144 patients underwent elective endovascular graft placement for infrarenal AAA disease at the authors' institution. These patients were treated with use of the AneuRx bifurcated endoprosthesis. AAA size (maximum aneurysm diameter) and proximal aortic neck length were compared to estimated blood loss, operative time, accuracy of graft placement, presence of endoleak, intraoperative and postoperative complications (such as limb occlusion or vascular injury), length of hospital stay, and mortality. Statistical methods included correlation analysis and logistic regression. RESULTS: There were 121 men and 23 women whose aneurysms ranged in size from 3 cm to 9.8 cm (mean, 5.6 cm; 95% CI, 5.4-5.8 cm). Endograft insertion was successful in all cases. There were three deaths within 30 days (2.1%) and seven deaths overall (4.9%). There were 43 intraoperative complications (29.9%) in 31 patients (21.5%), most of them minor. Patients with major intraoperative complications had significantly longer procedure times than those without complications (337 vs. 149 min; P <.0001). In the postoperative period (within 30 days), 31 complications (21.5%) occurred in 28 patients (19.4%), again most of them minor. AAA size was unrelated in any way to the rate of complications, but short proximal aortic neck length was associated with more serious intraoperative and postoperative complications (P =.0404 and P =.0230, respectively), and decreased 30-day and overall survival (P =.0240 and P =.0152, respectively). CONCLUSIONS: Endovascular repair of large AAAs can be challenging; however, the size of the AAA does not influence the rate of complications. A short proximal aortic neck is the only significant risk factor for more serious complications.