Biomedical subjects
Publications and source records attributed to C E Thomas.
We describe the use of a transcervical-transclival approach in the treatment of an ascending luxation of the odontoid by rheumatoid arthritis. We favor this approach and use of methylmethacrylate in this rare condition. Other applications of this route which gives access to the craniocervical junction are discussed.
The reason for the failure of glomerular filtration rate (GFR) to exhibit plasma flow dependency during pharmacologic vasodilation remains unclear although it has been suggested on the basis of experiments in rats that vasodilators may lead to a reduction in the glomerular filtration coefficient (Kf). To evaluate the applicability of this hypothesis to the dog, the effects of vasodilation with acetylcholine on glomerular dynamics and Kf were evaluated in two groups of dogs. One group (n = 19) was studied at spontaneous arterial pressures to allow maximum vasodilation to occur. In the other group (n = 5), renal arterial pressure was reduced and maintained at approximately 89 mmHg. Glomerular filtration rate and single nephron glomerular filtration rate were not altered significantly during acetylcholine infusion in either of the two groups. Both whole kidney and superficial filtration fractions decreased significantly. At spontaneous arterial pressures, transglomerular hydrostatic pressure was not altered significantly because of equivalent increases in proximal tubule pressure and in glomerular pressure. In the dogs studied at reduced renal perfusion pressure, glomerular capillary pressure did not change, but proximal tubule pressure increased slightly. Average effective filtration pressures and Kf were not significantly altered during the infusion of acetylcholine either at spontaneous or reduced renal perfusion pressures. These observations indicate that Kf in the dog is not significantly decreased by acetylcholine and that GFR is not affected during infusion of this agent because the effective filtration pressure is not significantly altered.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Effects of reduced glutathione (GSH) were investigated on in vitro lipid peroxidation of hepatic microsomes obtained from Long-Evans Hooded rats fed chemically defined, purified diets containing adequate or documented deficiencies of vitamin E (E), selenium (Se) or both. Glutathione inhibited lipid peroxidation mediated by both NADPH-dependent enzymatic and ascorbate-dependent non-enzymatic systems. The inhibitory effect of GSH was observed in microsomes obtained from E supplemented groups whereas it has no effect on microsomes from E deficient animals. Selenium status had no effect on GSH inhibition. Glutathione was found to be specific for the E dependent inhibition of lipid peroxidation and could not be substituted by other sulfhydryl compounds tested. Also, GSH did not inhibit non-enzymatic lipid peroxidation of heat-denatured microsomes from either E-supplemented groups or any of the other dietary regimens.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Although it is recognized that vasodilator-induced increases in renal plasma flow are not associated with increases in glomerular filtration rate (GFR), the mechanism responsible for the failure of GFR to exhibit plasma flow dependency under these circumstances remains uncertain. To evaluate this problem further, the effects of intra-arterial infusion of two vasodilators, bradykinin (n = 7) and papaverine (n = 6), on renal hemodynamics and glomerular function of dogs were determined. Both agents increased renal blood flow; however, GFR and single nephron GFR (SNGFR) remained unchanged during bradykinin infusion and decreased significantly during papaverine infusion. Transglomerular hydrostatic pressure and mean effective filtration pressure were not altered during bradykinin infusion but were significantly reduced by papaverine. Neither agent altered the glomerular filtration coefficient. These observations indicate that, in the dog, the GFR responses during renal vasodilation are dependent primarily on the effective filtration pressure.
We studied ischemic acute renal failure in 28 dogs by micropuncture, microsphere, morphologic, and whole kidney hemodynamic techniques, 18 to 24 hours after the renal artery was clamped (clamping time, 60 to 90 min). Before the artery was clamped, renal blood flow (RBF) averaged 3.49 +/- (SEM) 0.23 ml/min x g and was not significantly different (3.70 +/- 0.34 ml/min x g) 18 hours after the ischemic episode. RBF autoregulatory capability was, however, significantly reduced. Fractional outer cortical blood flow decreased slightly from 41 +/- 2 to 36 +/- 3% (P less than 0.05) postischemia. Single nephron glomerular filtration rate (SNGFR) was highly variable from one animal to the next and ranged from 0 to 87 nl/min (mean, 36 +/- [SEM] 7 nl/min) in a manner similar to whole kidney inulin clearance, which ranged from 0 to 0.56 ml/min x g (mean, 0.30 +/- 0.05 ml+min x g). The correlation coefficient between SNGFR and inulin clearance was highly significant, indicating an association between SNGFR and whole kidney GFR. Proximal tubule pressure (PTP) averaged 20 +/- (SEM) 1 mm Hg. In 6 dogs, the glomerular filtration coefficient (Kf) was determined by measurements of stop-flow pressure, colloid osmotic pressure, SNGFR, PTP, and single nephron filtration fraction, Kf was below that obtained for control animals. Scanning electron microscopy (SEM) studies indicated that the endothelial fenestrations were reduced in number and size. These studies suggest that one major characteristic of ischemic nephropathy in the dog is a derangement in the filtration process. The maintenance of RBF in the postischemic phase may occur by utilization of the autoregulatory reserve of the renal vasculature.
To determine if the glomerular filtration coefficient (Kf) of the dog is influenced by changes in plasma colloid osmotic pressure (COP), we conducted micropuncture experiments in dogs given concentrated albumin solutions. In one group (N = 9), filtration dynamics were evaluated following infusion of 450 to 600 ml of a 25% bovine albumin solution. To minimize the effects of acute volume expansion, we also achieved high COP levels in another group (N = 7) by albumin loading on the day prior to the experiment. In all experiments, renal arterial pressure was reduced to approximately 90 mm Hg to minimize potential errors that might lead to overestimation of single nephron filtration rate (SNGFR) and glomerular pressure (GP). In the acutely expanded dogs, COP increased to 23.0 +/- (SEM) 0.9 mm Hg, SNGFR was 59 +/- 6 nl/min, estimated GP was 61.0 +/- 2.0 mm Hg, proximal tubule pressure (PTP) was 23.0 +/- 1.6 mm Hg, and superficial filtration fraction (SFF) was 0.13 +/- 0.02. A similarly reduced whole kidney filtration fraction was also observed, due almost entirely to a marked increase in renal blood flow. When compared to noninfused control dogs (N = 13), Kf was significantly higher in the dogs with elevated COP, being 5.3 +/- 0.6 nl/min/mm Hg as compared to 3.4 +/- 0.3 nl/min/mm Hg. Average effective filtration pressure (EFP) was 12 +/- 1mm Hg, and EFP at the efferent end of the glomerular capillaries was 8.9 +/- 1.2 mm Hg. In the group infused on the prior day, COP was 20.0 +/- 0.8 mm Hg, SFF was 0.26 +/- 0.01, SNGFR was 70 +/-8 nl/min, GP was 59 +/- 2 mm Hg, and PTP was 19.0 +/- 1.5 mm Hg. Average EFP was 15 +/- 1 mm Hg, and EFP at the efferent end of the capillaries was 7.5 +/- 0.7 mm Hg. kf was 4.85 +/- 0.66 nl/min/mm Hg, a value significantly higher than that obtained in control dogs having a COP of 15.0 +/- 0.6 mm Hg. Furthermore, one group of control dogs (N = 4), expanded with an isooncotic albumin solution, did not exhibit significant changes in Kf even though the degree of plasma volume expansion was similar to the group expanded with concentrated albumin solution. These experiments are consistent with previous findings obtained in the rat that Kf is influenced by the COP, although the changes in Kf appear to be less than they are in the rat. The data indicate that even under these conditions of elevated COP, the filtration process in the dog is characterized by positive filtration pressures throughout the length of the glomerular capillaries.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Case report of a 14 year old girl with Hodgkin's disease whose echocardiographic findings showed an anterior mediastinal mass between the right ventricle and the chest wall. The echocardiogram permitted an accurate measurement of the AP diameter of the mass. This technique, in conjunction with chest x ray, provides a means of determining changes in overall mass size as an indication of response to therapy.
Our experience with cavernospongiosum shunts in the treatment of patients with priapism seen during the past four years is reviewed, and the surgical technique and results are presented.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.