Adult mongrel dogs, weighing 10-17 kg. were anesthetized with Nembutal and cervical and lumbosacral laminectomy was performed. The spinal subarachnoid space was blocked by extradural ligation at the ...level of the C4 to interrupt CSF communication between the cranial and spinal space. Polyethylene catheters were placed in the cervical and lumbosacral subarachnoid space, and artificial Mock CSF buffer, pH 7.35-7.40, containing inulin of 25 mg/dl or 14C-inulin of 1.5-2 muCi/dl as a tracer was perfused in the sacro-cervical direction through the catheter. After a steady state of perfusion was acommplished, the CSF was collected from the outlet catheter. Production and absorption rate of the CSF were calculated after Pappenheimer and Heisey's equation. 1) Effects of CSF pressure on the rate of production (Vf) and absorption (Va) of CSF and on the difference between outflow fluid rate (Vo) and inflow fluid rate (Vi) were studied within the pressure range of -100 to +600 mmH2O. Then, regression lines were calculated by means of the least square method. See Article. Vf was little affected by changes in CSF pressure, while Va increased linearly as CSF pressure elevated. This suggests that the spinal subarachnoid space plays an important role as a site of CSF absorption when the intracranial pressure increases. Vo-Vi, that is difference between absorption and production rate, decreased linearly as the CSF pressure increased. 2) Under a constant CSF pressure of +200 mmH2O, the effects of glucocorticoids (dexamethasone, 0.25 mg/kg and hydrocortisone, 4.15 mg/kg) and a carbonic anhydrase inhibitor (acetazolamide, 10 mg/kg) upon the production and absorption rate of CSF were determined 1/2, 1, 2 and 3 hours after intravenous administration. a) Effect of dexamethasone: The rate of CSF production was reduced to 60.5 +/- 2.4% (p less than 0.001) of the control level. The absorption rate of CSF also decreased to 59.2 +/- 6.09% (p less than 0.001) of the control. b) Effect of hydrocortisone: The production rate of CSF decreased to 67.4 +/- 6.61% (p less than 0.001), and the absorption rate to 76.5 +/- 3.94% (p less than 0.001) of the control level. c) Effect of acetazolamide: The production and absorption rate also decreased to 57.2 +/- 5.61% (p less than 0.001) and to 56.9 +/- 7.02% (p less than 0.001), respectively. 3) Pentration of tritiated dexamethasone and tritiated hydrocortisone from plasma to CSF. The penetration of tritiated dexamethasone and tritiated hydrocortisone from plasma to CSF in the spinal and cranial subarachnoid space was observed after the intravenous administration. The CSF/Plasma ratio of dexamethasone was 30.9% at 15 minutes and gradually increased to 91.5% and 93.5%, respectively, in the cranial and spinal CSF at 3 hours after the injection.
PURPOSE. There is considerable evidence that vascular endothelial growth factor (VEGF) mediates ocular neovascularization in retinal vascular diseases. We investigated the time-dependent changes in ...the expression of VEGF and its receptor KDR/Flk in a transient retinal ischemia-reperfusion injury model. METHODS. Transient retinal ischemia was induced by increasing the intraocular pressure in albino rats eyes for 45 min. In situ hybridization was used to identify the retinal cells synthesizing VEGF mRNA and KDR mRNA at various times following reperfusion. Immunohistochemical analysis was also carried out to detect VEGF immunoreactivity. RESULTS. In the control, non-ischemic retinas, signals for VEGF mRNA and KDR mRNA were observed in the cells of the ganglion cell layer. Immunoreactivity to VEGF was also found in the nerve fiber layer, the ganglion cell layer, and the retinal pigment epithelial (RPE) cell layer. Immediately and 6 h after reperfusion, VEGF and KDR mRNA expression was markedly decreased, but recovered by 24 h to the levels observed in normal retinas. Immunoreactivity for VEGF was also decreased immediately and 6 h after reperfusion, and was detected in the endothelial cells of the retinal vessels after 24 h. Immunoreactivity to VEGF recovered by 48 h after reperfusion. CONCLUSIONS. The hybridization pattern of VEGF and KDR mRNA in the ganglion cell layer strongly suggests that the ganglion cells are the major source of this growth factor. The decrease of VEGF mRNA, KDR/Flk mRNA and VEGF protein levels after ischemia and recovery after reperfusion suggest that transient hypoxia might mediate short-term down-regulation of VEGF and KDR mRNA.
An image watermarking scheme using the previously proposed bit embedding method is developed. To achieve a desired subjective visual quality in the watermarked image, the embedding parameter that is ...related to both the image quality and the embedding capacity is determined by using a perceptual model. First, based on the properties of the bit embedding method, the perceptual model of two kinds of objective quality measures is assumed. Then, the measurements of human subjective image quality are analyzed from the viewpoint of the correlation with these two measures. Thereby, the estimating function that can yield an estimate of the subjective quality from two objective measurements is determined. According to the estimating function, the bit embedding method performs in each image region so as to achieve a desired subjective image quality while increasing the capacity of embedding watermark bits. The simulation results demonstrate that the estimating function values have a linear correlation with human subjective evaluations, and the embedding parameters can be adaptively changed in every image region by using the function.
The effectiveness of repeated hepatic dearterialization (RHD) therapy was evaluated in 26 patients with unresectable primary and secondary liver tumors. RHD was performed in 12 patients with ...hepatocellular carcinoma (HCC), 7 with hepatic metastases from colorectal carcinoma, and 7 with hepatic metastases from gastric carcinoma. It was repeatedly carried out by occluding the hepatic artery for 1 h twice daily. All patients concurrently received an intra-arterial infusion of anticancer drugs. More than 50% remission of the hepatic tumors, defined as a partial response (PR), was demonstrated in 8 patients (31%). A higher PR was seen in hepatic tumors from metastatic gastric cancer (5 out of 7 patients; 71%). Most patients who suffered severe complications had HCC with liver cirrhosis. These preliminary results suggest that RHD with intra-arterial chemotherapy is an acceptable palliative treatment for patients with unresectable liver metastasis from gastric cancer; however, the majority of patients with HCC are not responsive to such treatment, primarily because most have underlying cirrhosis predisposing to the development of postoperative complications at an unacceptably high rate.
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