Papers by George Schuessler
PubMed, 1988
The aortic endothelium from control and Escherichia coli (E. coli) endotoxin-treated rats and rab... more The aortic endothelium from control and Escherichia coli (E. coli) endotoxin-treated rats and rabbits was examined by transmission and scanning electron microscopy. Following the intravenous injection of endotoxin, the animals were sacrificed at intervals ranging from 1 min to 4 hr. As early as 1 min after endotoxin, there was a widening of the subendothelial space (SES) and an increase in tortuosity of the internal elastic lamina (IEL). At 5 min, the tortuosity of the IEL increased to a peak value, and the SES showed an increase in the amount of smooth muscle cells (SMC). Initial endothelial damage occurred 5 min after endotoxin: SEM showed some spindle-shaped endothelial cells starting to peel from the underlying SES, and TEM showed some endothelial cells protruding or arching into the lumen. The new findings in this study are that endotoxin injection a) has a very rapid (less than 15 min) effect on rat and rabbit aortic endothelium, including localized endothelial injuries in the intima, and b) induces ultrastructural alterations also in the SES, IEL and portions of the tunica media. These effects were largely reversed within 1 hr after endotoxin administration, thus indicating that the endothelium and other components of the arterial wall can recover with great speeds.
Anesthesiology, Sep 1, 1982
Biochimica Et Biophysica Acta - Biomembranes, Nov 1, 1986
The normal, discoid shape of red blood cells represents an equilibrium between two opposing facto... more The normal, discoid shape of red blood cells represents an equilibrium between two opposing factors, i.e., stomatocytic and echinocytic transformations. Most stomatocytic agents were found to be inhibitors of caimodulin, a regulator of the phosphorylation of membrane proteins. We determined whether red cell shape transformations could be eaused by changes in phosphorylation of membrane proteins, specifically the cAMP-dependent phosphorylation of ankyrin and band 4.1. Red blood cells were incubated with 32p and 100 /tM chlorpromazine (stomatocytic transformation) or 30 mM sodium salicylate (echinocytic transformation) for various time intervals. Ghost membrane proteins were examined by polyacrylamide gel electrophoresis and autoradiography. Spectrin (fl-chain), ankyrin, band 3, band 4.1 and 4.9 were phosphorylated. No change was found in the degree and pattern of phosphorylation after stomatocytic transformation. Salicylate caused a reversible inhibition of transmembranous phosphate transport in both directions. The results indicate that the stomatocytic transformation induced by chiorpromazine and the echinocytic transformation induced by salicylate do not involve a change in phosphorylation, but that the echinocytic transformation induced by salicylate is associated with an inhibition of transmembranous transport of phosphate. Studies with salicylate suggest that the phosphorylation sites of band 3 are found mainly on the endofacial side of the membrane.
Journal of Ultrastructure and Molecular Structure Research, Nov 1, 1988
The purpose of the present experiment was to study the effects of internal hydrostatic pressure o... more The purpose of the present experiment was to study the effects of internal hydrostatic pressure on vesicle size, density, and distribution in the canine carotid arterial endothelium by transmission electron microscopy. The pressures applied in this study were 0 (control), 40,60,80. 100, and I50 mm Hg. The results of transmission electron microscopy and computer analysis on the plasma-lemma1 vesicles of aortic endothelium showed that luminal, abluminal, and junctional vesicles all increased their diameter as the pressure was raised from 0 mm Hg, reaching a maximum at 80 mm Hg, and then decreased in size with further increases in pressure to 150 mm Hg. There was a significant difference in diameter among vesicles in different regions of the endothelium, with the diameter of luminal vesicles larger than those of abluminal and junctional vesicles. The densities of vesicles showed very little change from 0 to 80 mm Hg; but they increased markedly as the pressure was further raised from 80 to 150 mm Hg. These results indicate that pressure is an important mechanical factor governing the size and density of plasmalemmal vesicles in aortic endothelium. 8.
Anesthesiology, Sep 1, 1984
Journal of Cerebral Blood Flow and Metabolism, Apr 1, 1987
A new experimental model was employed to investigate alterations of cerebral metabolic activity i... more A new experimental model was employed to investigate alterations of cerebral metabolic activity in rats subjected to extensive subarachnoid hemorrhage (SAH). The hemorrhages were produced in anesthetized animals by inserting 0.37 ml fresh autologous arterial blood into the subarachnoid space. Rats that underwent sham operations received subarachnoid injections of mock CSF to study the effects of sudden raised intra cranial pressure (lCP). Forty-eight hours after subarach noid injection, the unanesthetized rats were given intra venous injections of [14Cl2-deoxyglucose. Experiments were terminated 45 min later by decapitation, and the brains were removed and frozen. Regional brain meta bolic activity was studied employing quantitative autora diography. In comparison with control animals, cerebral Following acute subarachnoid hemorrhage (SAH) from rupture of an intracranial aneurysm, vasospasm of the large cerebral arteries often de velops. In patients with vasospasm, about 50% de velop the syndrome of delayed cerebral ischemia (Fisher et aI., 1977; Fisher et aI., 1980), presumably related to increased vascular resistance in the vaso spastic arteries. However, numerous clinical and laboratory studies have documented global changes in CBF and metabolism that are unrelated to vaso
Anesthesiology, Sep 1, 1979
American Journal of Physiology-regulatory Integrative and Comparative Physiology, Jul 1, 1982
The baroreflex control of heart rate was investigated on 10 informed human subjects during light ... more The baroreflex control of heart rate was investigated on 10 informed human subjects during light halothane anesthesia (0.3-0.5%, inspired concentration). The relationship of systolic pressure (SP) to the succeeding pulse interval (PI) was evaluated on a beat-to-beat basis during the entire course of sodium nitroprusside (SNP) depressor test. The initial slope of SP-PI plot (dPI/dSP) was used as an index of the sensitivity of baroreflex control of heart rate. Following an injection of SNP (4-6 micrograms/kg), dPI/dt was related directly to dPI/dSP, whereas the latter was inversely correlated with dSP/dt. The recovery of PI lagged behind that of SP, and there was a hysteresislike loop on the SP-PI plot. The time lag of PI recovery and the loop of SP-PI plot were markedly decreased by propranolol treatment and significantly increased by atropine. The slopes of SP-PI plot were significantly decreased by atropine but relatively unaffected by propranolol. These results indicate that SNP-induced hypotension in man during halothane anesthesia is associated with a withdrawal of parasympathetic inhibition and an enhancement of sympathetic activity. The autonomic control of heart rate in response to rapid changes in arterial pressure induced by SNP is dominated by parasympathetic influence; the more persistent sympathetic activity only becomes evident when the parasympathetic influence subsides quickly as the arterial pressure stays relatively constant at a new level. The slope of SP-PI plot (dPI/dSP) and the ratio of dPI/dt to dSP/dt during the decreasing pressure phase of SNP test can be used as indices for the sensitivity of baroreflex control of heart rate.
Stroke, Sep 1, 1983
Regional cerebral blood flows and shunting of microspheres with four different sizes (9,12, 16 an... more Regional cerebral blood flows and shunting of microspheres with four different sizes (9,12, 16 and 25 /u,m) into the superior sagittal sinus were determined in twelve dogs. Venous blood was collected from the superior sagittal sinus for 120 min after the injection of microspheres, and the dogs were then sacrificed immediately. Results on blood flow measurements and venous shunting determinations were similar between left ventricular and left atrial injections. Blood flows measured by 12,16 and 25 /xm spheres were comparable in various brain tissues, except the choroid plexus. 9 ju.m spheres underestimated blood flows in all regions studied: by 13-19 percent in the cerebral cortex, midbrain, brain stem and cerebellum, by 34-42 percent in the cortical white matter, corpus callosum and cervical cord, and by 64-81 percent in pituitary gland and choroid plexus. These results probably reflect regional difference in microvascular architecture. Venous shunting of 9,12,16 and 25 p-tn spheres during a 2 hr period were 23.6 ± 2.5,12.6 ± 1.2, 4.8 ± 1.4, and 4.0 ± 1.2 percent (mean ± SEM), respectively, with respect to the arterial delivery. Although most of the venous shunting occurred during the first 3 min after the injection of microspheres, it continued 3-60 min after the injection. Beyond 60 min, the venous shunting became minimal for 16 and 25 /urn spheres, while significant amount of 9 jam spheres continued to appear in sagittal sinus. This time dependent shunting indicates that some microspheres may be transiently trapped in the microcirculation and become gradually dislodged with time. Failure to consider this time dependence may underestimate the shunting of microspheres through the microcirculation. The difference in percent shunting between 9 and 15 (im spheres estimated by cerebral cortex counting agreed well with that by sagittal sinus sampling when both were determined at 120 min after the injection of microspheres.
Archives of Oral Biology, 1983
Following rapid injection of L33Xe into the maxillary artery, the radioactivity from a dog canine... more Following rapid injection of L33Xe into the maxillary artery, the radioactivity from a dog canine tooth was monitored with a specially-designed scintillation probe connected to a multichannel analyser. With a PDP 1 l/10 municomputer, the semilogarithmic radioactivitytime curve was resolved into a fast component and a slow component using best fit least-square lines and the exponential rate constant (k) was determined for each component. The blood flow per unit of pulp mass (Q, in ml/min per 100 g) was obtained using the equation: Q = k.&,, where i.,, is the tissue-blood partition coefficient of "'Xe in the pulp determined for the haematocrit value of the individual experiments. The fast-component blood flow was 53.12 & 3.12 and the slow-component blood flow was 8.86 k 0.53 ml/min per 1OOg (mean + SEM, n = 21). Although the exact anatomical areas for the fast and slow components are yet to be determined, the results show heterogeneity of blood flow in the pulp. The study showed that pulp blood Ilow in an intact tooth can be measured with the 133Xe washout method; the method enables study of circulatory physiology of the pulp in health and disease.
American Journal of Physiology-Heart and Circulatory Physiology, 1979
In 17 pentobarbitalized dogs, the shunting of 15-micrometer and 9-micrometer microspheres was stu... more In 17 pentobarbitalized dogs, the shunting of 15-micrometer and 9-micrometer microspheres was studied in the brain, myocardium, kidney, intestine, and lung. The veins of these organs were catheterized for constant blood withdrawal for 2 min by direct venipuncture. The ratio of microsphere radioactivity in the venous blood to that in the arterial blood gave the shunting of microspheres by the venous sampling technique. The 15-micrometer microspheres showed 2% or less shunting for all organs studied, whereas the 9-micrometer microspheres had shunting ranging from 3% in the coronary sinus to 24% in the portal vein. The shunting of 9-micrometer microspheres was also calculated from direct tissue counting, where the 15-micrometer spheres were considered to be completely entrapped. The results of direct tissue counting indicate that the 2-min venous sampling underestimates microsphere shunting. CO2 administration increased significantly the shunting of 9-micrometer spheres, whereas the sh...
American Journal of Physiology-Heart and Circulatory Physiology, 1980
The responses of alterations in regional hemodynamics and oxygen transport rate to hematocrit (Hc... more The responses of alterations in regional hemodynamics and oxygen transport rate to hematocrit (Hct) were studied in 20 pentobarbitalized dogs. Hemodilution was carried out by isovolemic exchange with plasma in 12 dogs and the hemoconcentration with packed cells in 8 dogs. The cardiac output and regional blood flows were determined with the microsphere technique. In hemodilution, the increases of blood flow to the myocardium and the brain were out of proportion to the increase of cardiac output; the oxygen supply to the myocardium remained unchanged while that to the brain decreased only slightly. In hemoconcentration, vasodilation occurred in the myocardium and the brain to maintain constant oxygen supply. Splenic vessels had marked vasoconstriction with Hct alteration in either direction. Blood vessels in the liver, intestine, and kidney responded with a milder vasoconstriction and maintained a constant oxygen supply between Hct of 30-55%. Therefore, during Hct alteration, redistri...
FC Fan, RY Chen, GB Schuessler and S Chien in cerebral blood flow determinations in the dog Compa... more FC Fan, RY Chen, GB Schuessler and S Chien in cerebral blood flow determinations in the dog Comparison between the 133Xe clearance method and the microsphere technique 1524-4571 SUMMARY We compared the 1M Xe clearance method and the microsphere technique (15-pm spheres) for cerebral blood flow determination in 16 mongrel dogs. The lu Xe clearance curve obtained from sampling dorsal sagittal sinus blood following left ventricular injection showed either two or three components. Blood flow calculated from the first component can be correlated with the average gray matter blood flow through the caudate nucleus, the cortical gray, and the thalamus calculated from the microsphere data. The second component of the llJ Xe curve correlated well with the white matter blood flow measured with microspheres. In seven out of 15 experiments, there was a third component in the lu Xe clearance curve. The blood flow obtained from the third component showed a close correlation with extracranial muscle blood flow determined with microspheres. The mean cerebral blood flow measured with the '"Xe clearance method was in close agreement with that obtained by the microsphere technique. After the injection of lu Xe into extracranial muscles, the slope of the clearance curve obtained from the dorsal sagittal sinus correlated well with that of the third component following left ventricular injection. The results indicate that regional cerebral blood flows measured with 15-fim microspheres can be correlated with those obtained from various components of the simultaneous m Xe clearance. These findings also point out the necessity of considering the contribution of extracranial muscles when analyzing the 1M Xe clearance curve. Circ Ret 44: 6S3-6S9, 1979
Regional cerebral blood flows and shunting of microspheres with four different sizes (9,12, 16 an... more Regional cerebral blood flows and shunting of microspheres with four different sizes (9,12, 16 and 25 /u,m) into the superior sagittal sinus were determined in twelve dogs. Venous blood was collected from the superior sagittal sinus for 120 min after the injection of microspheres, and the dogs were then sacrificed immediately. Results on blood flow measurements and venous shunting determinations were similar between left ventricular and left atrial injections. Blood flows measured by 12,16 and 25 /xm spheres were comparable in various brain tissues, except the choroid plexus. 9 ju.m spheres underestimated blood flows in all regions studied: by 13-19 percent in the cerebral cortex, midbrain, brain stem and cerebellum, by 34-42 percent in the cortical white matter, corpus callosum and cervical cord, and by 64-81 percent in pituitary gland and choroid plexus. These results probably reflect regional difference in microvascular architecture. Venous shunting of 9,12,16 and 25 p-tn spheres during a 2 hr period were 23.6 ± 2.5,12.6 ± 1.2, 4.8 ± 1.4, and 4.0 ± 1.2 percent (mean ± SEM), respectively, with respect to the arterial delivery. Although most of the venous shunting occurred during the first 3 min after the injection of microspheres, it continued 3-60 min after the injection. Beyond 60 min, the venous shunting became minimal for 16 and 25 /urn spheres, while significant amount of 9 jam spheres continued to appear in sagittal sinus. This time dependent shunting indicates that some microspheres may be transiently trapped in the microcirculation and become gradually dislodged with time. Failure to consider this time dependence may underestimate the shunting of microspheres through the microcirculation. The difference in percent shunting between 9 and 15 (im spheres estimated by cerebral cortex counting agreed well with that by sagittal sinus sampling when both were determined at 120 min after the injection of microspheres.
The American journal of physiology
ABSTRACT
Artery
The aortic endothelium from control and Escherichia coli (E. coli) endotoxin-treated rats and rab... more The aortic endothelium from control and Escherichia coli (E. coli) endotoxin-treated rats and rabbits was examined by transmission and scanning electron microscopy. Following the intravenous injection of endotoxin, the animals were sacrificed at intervals ranging from 1 min to 4 hr. As early as 1 min after endotoxin, there was a widening of the subendothelial space (SES) and an increase in tortuosity of the internal elastic lamina (IEL). At 5 min, the tortuosity of the IEL increased to a peak value, and the SES showed an increase in the amount of smooth muscle cells (SMC). Initial endothelial damage occurred 5 min after endotoxin: SEM showed some spindle-shaped endothelial cells starting to peel from the underlying SES, and TEM showed some endothelial cells protruding or arching into the lumen. The new findings in this study are that endotoxin injection a) has a very rapid (less than 15 min) effect on rat and rabbit aortic endothelium, including localized endothelial injuries in the intima, and b) induces ultrastructural alterations also in the SES, IEL and portions of the tunica media. These effects were largely reversed within 1 hr after endotoxin administration, thus indicating that the endothelium and other components of the arterial wall can recover with great speeds.
The American journal of physiology
The baroreflex control of heart rate was investigated on 10 informed human subjects during light ... more The baroreflex control of heart rate was investigated on 10 informed human subjects during light halothane anesthesia (0.3-0.5%, inspired concentration). The relationship of systolic pressure (SP) to the succeeding pulse interval (PI) was evaluated on a beat-to-beat basis during the entire course of sodium nitroprusside (SNP) depressor test. The initial slope of SP-PI plot (dPI/dSP) was used as an index of the sensitivity of baroreflex control of heart rate. Following an injection of SNP (4-6 micrograms/kg), dPI/dt was related directly to dPI/dSP, whereas the latter was inversely correlated with dSP/dt. The recovery of PI lagged behind that of SP, and there was a hysteresislike loop on the SP-PI plot. The time lag of PI recovery and the loop of SP-PI plot were markedly decreased by propranolol treatment and significantly increased by atropine. The slopes of SP-PI plot were significantly decreased by atropine but relatively unaffected by propranolol. These results indicate that SNP-induced hypotension in man during halothane anesthesia is associated with a withdrawal of parasympathetic inhibition and an enhancement of sympathetic activity. The autonomic control of heart rate in response to rapid changes in arterial pressure induced by SNP is dominated by parasympathetic influence; the more persistent sympathetic activity only becomes evident when the parasympathetic influence subsides quickly as the arterial pressure stays relatively constant at a new level. The slope of SP-PI plot (dPI/dSP) and the ratio of dPI/dt to dSP/dt during the decreasing pressure phase of SNP test can be used as indices for the sensitivity of baroreflex control of heart rate.
The American journal of physiology
ABSTRACT
Journal of Endodontics, 1980
This is the third of a five-part series (the second article) to appear in the Journal as part of ... more This is the third of a five-part series (the second article) to appear in the Journal as part of a Symposium on circulatory physiology of the pulp.
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Papers by George Schuessler