The ability of gene targeting in the mouse species presents a powerful tool to determine the role of specific molecules in vascular biology. Using a denuding-injury procedure, we recently reported that intimal lesions can be induced in the carotid artery of outbred mice. The technical challenge associated with achieving complete denudation and the relatively small size of the developing lesions prompted us to design the present model of neointima formation and vascular remodeling in the carotid artery of the inbred FVB mouse strain. Complete ligation of the vessel near the carotid bifurcation induced rapid proliferation of medial smooth muscle cells, leading to extensive neointima formation in the presence of an endothelial lining. Thrombus formation was not observed except in the most distal part of the vessel adjacent to the ligature. At 4 weeks after ligation, luminal area was reduced by approximately 80% through a combination of decreased vessel diameter and neointima formation. Ultrastructural analysis provided evidence for cell death in the developing neointima as well as the remodeling media. The present model might be useful in identifying those genes important for neointima formation and vascular remodeling.

These data suggest that P-selectin is involved in processes leading to cell migration and proliferation associated with vascular remodeling, presumably by mediating leukocyte recruitment and the interaction between platelets and leukocytes.

This study demonstrates that high circulating levels of P-selectin are associated with increased thrombosis, whereas a lack of P-selectin and E-selectin is associated with a lessening of thrombosis. Additionally, leukocyte MPs are associated with venous thrombus formation. These data suggest the importance of selectins to venous thrombogenesis and show that P-selectin and leukocyte-derived MPs should be good targets to limit venous thrombus formation.

Important complications in sickle cell anemia occur secondary to vascular occlusion, which is postulated to be initiated by interactions of erythrocytes with vascular endothelial cells. In patients with sickle cell anemia, up to 25% of reticulocytes express the a&-integrin complex. Furthermore, erythrocytes from patients with sickle cell anemia bind to endothelial cells activated by tumor necrosis factor CY via (TNFa) via interactions between erythrocyte a& and OMPLICATIONS in sickle cell anemia, including he-C molytic anemia, increased infection, ischemic organ damage, and episodes of severe pain,' are manifestations of homozygosity for a single amino acid substitution of valine for glutamic acid in the 86 position ofthe globin chain.2 The

OBJECTIVEWe tested the hypotheses that human brain glycogen is mobilized during hypoglycemia and its content increases above normal levels (“supercompensates”) after hypoglycemia.RESEARCH DESIGN AND METHODSWe utilized in vivo 13C nuclear magnetic resonance spectroscopy in conjunction with intravenous infusions of [13C]glucose in healthy volunteers to measure brain glycogen metabolism during and after euglycemic and hypoglycemic clamps.RESULTSAfter an overnight intravenous infusion of 99% enriched [1-13C]glucose to prelabel glycogen, the rate of label wash-out from [1-13C]glycogen was higher (0.12 ± 0.05 vs. 0.03 ± 0.06 μmol · g−1 · h−1, means ± SD, P < 0.02, n = 5) during a 2-h hyperinsulinemic-hypoglycemic clamp (glucose concentration 57.2 ± 9.7 mg/dl) than during a hyperinsulinemic-euglycemic clamp (95.3 ± 3.3 mg/dl), indicating mobilization of glucose units from glycogen during moderate hypoglycemia. Five additional healthy volunteers received intravenous 25–50% enriched [1-13C]glucose over 22–54 h after undergoing hyperinsulinemic-euglycemic (glucose concentration 92.4 ± 2.3 mg/dl) and hyperinsulinemic-hypoglycemic (52.9 ± 4.8 mg/dl) clamps separated by at least 1 month. Levels of newly synthesized glycogen measured from 4 to 80 h were higher after hypoglycemia than after euglycemia (P ≤ 0.01 for each subject), indicating increased brain glycogen synthesis after moderate hypoglycemia.CONCLUSIONSThese data indicate that brain glycogen supports energy metabolism when glucose supply from the blood is inadequate and that its levels rebound to levels higher than normal after a single episode of moderate hypoglycemia in humans.