In a review of the vertebral angiograms of 300 patients free from disease at the craniovertebral junction, we found atlantoaxial arterial anomalies in 2,3%. These were: 2 cases in which the vertebral artery ran in the spinal canal below C1, 3 cases of duplication of the vertebral artery above and below C1, and 2 cases of origin of the posterior inferior cerebellar artery at C2. Although these arteries ran in the spinal canal between C1 and C2, they never encroached upon the posterior third of the canal. From the survey of another 21 patients having bony abnormalities at the craniovertebral junction, the first type of arterial anomaly described above was seen in 4 patients and associated with failure of segmentation of the embryonic sclerotome such as occipitalization of the atlas or Klippel-Feil syndrome. It is possible to relate the development of these anomalous vessels to malarrangement of the embryonic segmental arteries. Our results indicate that one must be cautious with lateral C1/2 puncture or surgical exposure of the region.
We investigated the role of nitric oxide (NO) in vascular endothelial growth factor (VEGF) expression in the rat placenta. A nitric oxide synthase (NOS) inhibitor, N(G)-nitro-L-arginine-methyl ester (L-NAME), was constantly infused into pregnant rats 6-24 h before sacrifice on gestational day (GD) 15.5. NO production declined to about 15% of the control level as monitored by NO trapping and electron paramagnetic resonance spectroscopy. VEGF mRNA expression was temporally decreased by L-NAME, but recovered to normal levels after 24 h of treatment, whereas hypoxia inducible factor (HIF)-1α and induced NOS (iNOS) expression increased. VEGF expression decreased significantly in placental explants after 6 h of co-treatment with L-NAME and lipopolysaccharide, an iNOS inducer. Our data indicate that NO induce VEGF expression in vivo and in vitro in the rat placenta, suggesting that peaked NO production was maintained by a reciprocal relationship between NO and VEGF via HIF-1α.
Regional blood flow to major organs and regional cerebral blood flow were determined in seven anesthetized male gerbils by a modified microsphere method. Carbonized microspheres, 15 micrometers in diameter and labeled with 85Sr or 141Ce, were injected into the left ventricle by cardiac puncture through the closed thorax, and reference samples of known volume were withdrawn from tail-artery cannula. No significant hemodynamic alterations were observed during microsphere administration, and extraction of 15-micrometers microspheres by the pulmonary or systemic capillary beds was nearly 100%. The adequacy of mixing of microspheres in the left ventricle was also validated. The absolute regional blood flow to various organs and regional cerebral blood flow were expressed in terms of milliliters per minute per gram tissue weight, and the values mostly agreed with those reported previously in rats. The results indicate that the reference sample method can be applied to the gerbil. This method should allow the gerbil, which is an animal widely used in stroke research, to be conveniently used for hemodynamic studies when organ blood flow and regional cerebral blood flow are necessary.
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