Peroxidative hemolysis of red blood cells from patients with abetalipoproteinemia (acanthocytosis).

The effect of peroxidative stress on tissue was studied by exposure of red blood cells (RBC) from patients with abetalipoproteinemia to minute amounts of H(2)O(2)in vitro. Red blood cells from untreated patients showed a marked sensitivity to H(2)O(2), as evidenced by hemolysis and lipid peroxidation (peroxidative hemolysis). The appearance of lipid peroxidation products in sensitive cells after exposure to H(2)O(2) was indicated by 1) increases in the 2-thiobarbituric acid (TBA) reaction of trichloroacetic acid extracts, 2) increases in ultraviolet light absorbency of lipid extracts, and 3) decreases in polyunsaturated fatty acids. These changes were accompanied by a decrease in phosphatidyl ethanolamine and phosphatidyl serine in the RBC lipid extract. Similar lipid changes on exposure to H(2)O(2) were observed in the RBC from vitamin E-deficient rats. Treatment of the patients with d-alpha-tocopherol polyethylene glycol succinate by mouth, or addition of dl-alpha-tocopherol to the incubation medium protected the RBC from peroxidative hemolysis. Tocopherol appears to provide a primary biologic defense against peroxidative hemolysis. The presence of nitrite or carbon monoxide, which produced methemoglobin and carboxyhemoglobin, respectively, inhibited peroxidative changes, suggesting a catalytic role for oxy- or deoxyhemoglobin. Substances that prevented lipid peroxidation also prevented hemolysis; in addition, lipid peroxidation appeared to precede hemolysis. These observations suggested that hemolysis was a consequence of lipid peroxidation.

Pathologic studies of the blood--retinal barrier in the spontaneously diabetic BB rat.

The BB rat spontaneously develops a diabetic state that closely resembles human type I diabetes. The authors studied the pathologic changes of the retina and retinal pigment epithelium of four normal and nine diabetic BB rats using (1) light and electron microscopy with the horseradish peroxidase tracer technique, and (2) trypsin digest preparations of the retinal vessels. They observed a retinal pigment epitheliopathy characterized by (1) derangement of the plasmalemma infoldings; (2) patchy organelle degeneration leading to focal necrosis; (3) increased permeability to horseradish peroxidase; and (4) repair of the pigment epithelium. Focal thickening of the retinal vascular basement membrane was seen occasionally, but the trypsin digest preparations were unremarkable. These studies suggest that diabetic retinal pigment epitheliopathy may be one of the early changes of diabetic retinopathy and may provide a pathogenetic mechanism for early disruption of the blood-retinal barrier.

Impact of injection rate on the Thrombolysis in Myocardial Infarction (TIMI) trial frame count.

A mechanical injection was used to determine the impact of injection rate on the TIMI frame count. The 1.0-ml/s increase in hand injection rates from the 10th to 90th percentiles for angiographers is associated with a minor decrease of <2 frames that is <7% of the corrected TIMI frame count.

Global impairment of coronary blood flow in the setting of acute coronary syndromes (a RESTORE substudy). Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis.

Acute coronary syndromes result in a global impairment of coronary blood flow with nonculprit artery blood flow being associated with culprit artery flow and vice versa. Improvements in nonculprit artery flow are related to improvements in culprit artery flow after percutaneous intervention; nonculprit arteries with abnormal flow sustain greater improvements in their flow after culprit artery intervention.

Angioplasty guidewire velocity: a new simple method to calculate absolute coronary blood velocity and flow.

The Thrombolysis In Myocardial Infarction (TIMI) frame count is a relative index of coronary flow that measures time by counting the number of frames required for dye to travel from the ostium to a standardized coronary landmark in a cineangiogram filmed at a known speed (frames/s). We describe a new method to measure distance along arteries so that absolute velocity (length divided by time) and absolute flow (area x velocity) may be calculated in patients undergoing percutaneous transluminal coronary angiography (PTCA). After PTCA, the guidewire tip is placed at the coronary landmark and a Kelly clamp is placed on the guidewire where it exits the Y-adapter. The guidewire tip is then withdrawn to the catheter tip and a second Kelly clamp is placed on the wire where it exits the Y-adapter. The distance between the 2 Kelly clamps outside the body is the distance between the catheter tip and the anatomic landmark inside the body. Velocity (cm/s) may be calculated as this distance (cm) divided by TIMI frame count (frames) x film frame speed (frames/s). Flow (ml/s) may be calculated by multiplying this velocity (cm/s) and the mean cross-sectional lumen area (cm2) along the length of the artery to the TIMI landmark. In 30 patients, velocity increased from 13.9 +/- 8.5 cm/s before to 22.8 +/- 9.3 cm/s after PTCA (p <0.001). Despite TIMI grade 3 flow both before and after PTCA in 18 patients, velocity actually increased 38%, from 17.0 +/- 5.4 to 23.5 +/- 9.0 cm/s (p = 0.01). For all 30 patients, flow doubled from 0.6 +/- 0.4 ml/s before to 1.2 +/- 0.6 ml/s after PTCA (p <0.001). In the 18 patients with TIMI grade 3 flow both before and after PTCA, flow increased 86%, from 0.7 +/- 0.3 to 1.3 +/- 0.6 ml/s (p = 0.001). Distance along coronary arteries (length) can be simply measured using a PTCA guidewire. This length may be combined with the TIMI frame count to calculate measures of absolute velocity and flow that are sensitive to changes in perfusion. TIMI grade 3 flow is composed of a range of velocities and flows.

Rhegmatogenous retinal detachment in Labrador retrievers. I. Development of retinal tears and detachment.

We used clinical and pathologic methods to examine ten Labrador retrievers with ocular and skeletal abnormalities. The major ocular findings were axial myopia; cataract; vitreous abnormalities, including liquefaction, detachment, and vitreoretinal traction; retinal tears; rhegmatogenous retinal detachment; and proliferative vitreoretinopathy. The appendicular skeleton showed retarded bone growth, bone dysplasia, and degenerative arthropathy. Vitreoretinal traction appeared to be the cause of the retinal tears because (1) formed vitreous was always attached near the anterior edge of the tear, and (2) vitreous traction caused a retinal ridge adjacent to a retinal tear in a dog that had not yet developed retinal detachment. The pathogenetic sequence of spontaneous vitreous abnormalities, retinal tears, and retinal detachment observed in these dogs has not previously been described in animals, to the best of our knowledge, and mimicked human rhegmatogenous retinal detachment, particularly those associated with giant retinal tears.

Rhegmatogenous retinal detachment in Labrador retrievers. II. Proliferative vitreoretinopathy.

We observed proliferative vitreoretinopathy in Labrador retrievers with spontaneous rhegmatogenous retinal detachment. Cellular membranes and their associated connective tissue matrix were prominent on the surfaces of the detached formed vitreous and on the retina. Membrane contraction folded the underlying vitreous and retina and exerted traction on the structures to which they attached. Proliferation occurred in the retinal pigment epithelium under the detached retina and in the nonpigmented ciliary epithelium when it became detached. Retinal pigment epithelial cells, nonpigmented ciliary epithelial cells, macrophages, and glial cells appeared to contribute to the membranes. Our findings suggested a sequence that began with vitreous abnormalities and ended with fibrocellular membranes on the surfaces of the vitreous and the totally detached retina. Because a similar sequence can develop in humans, these dogs may be useful in future studies of proliferative vitreoretinopathy.

The Open Artery Hypothesis: Past, Present, and Future.

The survival benefit following a reperfusion strategy, be it pharmacologic or mechanical, appears to be due to both full and early reperfusion. While the TIMI Flow Grade classification scheme has been a useful tool to assess coronary blood flow in acute syndromes, it has several limitations. A newer method of assessing coronary blood flow called the Corrected TIMI Frame Count method has the following advantages: (1) it is a continuous quantitative variable rather than a categorical qualitative variable; (2) the flow in the non-culprit artery is not assumed to be normal as it is in the assessment of TIMI Grade 3 Flow; (3) there is simplified reporting of reperfusion efficacy through the use of a single number instead of expressing the data in 2 to 4 categories; (4) because a single number rather than 4 categories is used to report the data, there is more efficient use of the dataset by increasing the statistical power; and finally (5) coronary flow can be expressed in intuitive terms (e.g. time or cm/sec for strategy A versus time or cm/sec for strategy B). This paper reviews the history of the open artery hypothesis and recent advances in the field.

Composition of phospholipids and of phospholipid fatty acids and aldehydes in human red cells.

Improved methods for lipid analysis that have been developed recently were employed to reevaluate the phospholipid composition, the fatty acid and fatty aldehyde composition of the total phospholipid, and the fatty acid composition of the individual phospholipids of normal human red cells. Thirty-three fatty acids and five fatty aldehydes were estimated and tentatively identified in the total phospholipid of normal human red cells. Additional minor components were evident. The major individual phospholipids were isolated by silicic acid thin-layer chromatography and quantified. The fatty acid compositions of phosphatidyl ethanolamine, phosphatidyl serine, lecithin, and sphingomyelin were determined. Each of these phospholipids showed a distinctive and characteristic fatty acid pattern.

Composition of phospholipids and of phospholipid fatty acids of human plasma.

The composition of the phospholipids and of the total phospholipid fatty acids was determined in the plasma of 10 normal subjects. In addition the fatty acid composition of the plasma phosphatidyl ethanolamine, phosphatidyl serine, lecithin, sphingomyelin, and lysolecithin of 6 of the subjects was measured. A wide array of fatty acids was found in the plasma total phospholipid similar to that found previously in red cell total phospholipid. The fatty acid composition in the plasma phospholipids of a given subject reflected that in his red cell phospholipids. Each individual phospholipid displayed a distinctive fatty acid pattern, which was generally similar to that of the corresponding phospholipid of red cells, although some marked differences in individual fatty acid levels between the corresponding phospholipids of plasma and red cells were evident. The high percentage of unsaturated fatty acids found in plasma lysolecithin suggests that this phospholipid did not arise entirely through the enzymatic cleavage of the -fatty acid of lecithin.

Autoxidation as a cause of altered lipid distribution in extracts from human red cells.

A characteristic alteration in the distribution of human red cell phospholipids represents an artifact due to autoxidation of the lipid extract. This alteration is manifested on silicic acid chromatography by a decrease mainly in the phosphatidyl ethanolamine and phosphatidyl serine fractions (probably because of their abundance of highly unsaturated fatty acids) and an increase in the phospholipid recovered with the more polar fractions, sphingomyelin and lysolecithin. No evidence was found for "lysocephalin" formation or plasmalogen breakdown in dry lipid extracts after autoxidation by exposure to air at room temperature for 24-35 hr. On thin-layer chromatography, however, the ninhydrin-positive streaking in the autoxidized samples may be erroneously attributed to the presence of "lyso" derivatives. When the alterations in lipid distribution described above are found, the possibility of this artifact should be considered.

Analysis of fatty acids of human red cells without lipid extraction.

Exposure of human red cells to 2 N HCl for 18-20 hr at 110 degrees C appears to release the total fatty acid, which can then be esterified for GLC analysis. This technique is simpler and may be more reliable than the conventional methods that depend on lipid extraction of the red cells.

Dendritic atrophy in the dentate gyrus of the senescent rat.

Quantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number, volume fraction and surface area of dendritic shaft profiles are significantly decreased in senescent rats, relative to young adults. These modifications of dendritic morphology, which are not associated with age-related changes in dimensions of the molecular layer or in numbers of granule cells, may result from a decrease in the number and/or length of dendrites. In either case, the decreases in the number, volume fraction and surface area of dendritic shaft profiles found in the dentate gyrus of senescent rats signify an age-related atrophy of dendrites. Comparison of changes in the number and volume fraction of dendritic shaft profiles has demonstrated that age-related dendritic atrophy involves predominantly dendritic branches.

Hypertrophy of astroglial processes in the dentate gyrus of the senescent rat.

Quantitative electron microscopic analysis of the supragranular zone of the dentate gyrus molecular layer has shown that the number and volume fraction of profiles of astroglial processes are significantly increased in senescent rat relative to young adults. These ultrastructural modifications, which are not associated with significant age-related changes in the number of astrocytes or in the width of the molecular layer, may result from a formation of new astroglial processes and/or elongation of existing ones. In either case, the increase in the number and volume fraction of astroglial process profiles is an indicator of age-related astroglial hypertrophy. Hypertrophy of astroglial procecesses, which seems to develop with advanced age as a response to partial deafferentation of neurons, may compensate for a decrease in the dendritic volume fraction, thereby preventing changes in the dimensions of the dentate gyrus molecular layer in senescence.

Magnitude of beta-adrenoceptor-mediated responses of dog epicardial coronary arteries: inverse relation to diameter.

Regional blood flow patterns vary within myocardium to suggest that intrinsic regional differences occur in vasoregulation. Accordingly, we used standard in vitro methodology (isometric force transducer) to study adrenergic responses in epicardial left anterior descending (LAD) artery and right coronary arteries (RCA) obtained from dogs (n = 9). In the presence of propranolol (10(-6) M) and blockers of uptake 1 and 2, norepinephrine (NE) elicited minimal, if any, constriction. After preincubation with phentolamine (10(-6) M) and preconstriction with prostaglandin (PG)F2 alpha or a thromboxane (Tx)A2 analogue, maximum NE relaxation (as % of induced tone) for the RCA was 61 +/- 3 (SE) %, which was significantly greater than the LAD (46 +/- 5%, P < 0.01). ED50 values were not different. Endothelial removal and forskolin relaxations did not change the sensitivity or maximal response between arteries. Expressing beta-adrenoceptor-mediated relaxation as a function of vessel diameter revealed a common regression for RCA and LAD (r = -0.56, P < 0.001). ED50 and diameter were minimally related. Thus the RCA has a greater beta-adrenoceptor response than the LAD in dogs. The difference appears to be reconciled by a common inverse relationship between vessel size and beta-adrenoceptor response. The difference was independent of alpha-adrenoceptor, endothelium, and second messenger processing, suggesting a mechanism based on beta-adrenoceptor density.

Comparison of density of sympathetic varicosities and their closeness to smooth muscle cells in rabbit middle cerebral and ear arteries and their branches.

The density and nerve varicosity-smooth muscle cell separation of rabbit cerebral and ear arterial beds were compared. The rabbit middle cerebral artery and three of its successive branches and a comparable-sized ear artery and two branches were perfusion-fixed for electron microscopy and analyzed by quantitative morphometric procedures. The purpose was to determine if there are structural correlates to previously observed differences in the sympathetic control of these two vascular systems. The in vitro contractile response of isolated artery segments to electrical field stimulation of their intramural nerves is considerably less in cerebral arteries compared with the similar-sized ear arteries. Furthermore, in the cerebral but not the ear circulation, there is progressive diminution of the neurogenic response with successive branching. Although the total varicosity densities of the major ear and brain arteries studied are similar, and this parameter stays fairly constant with successive branching of the ear, it falls off considerably in the cerebral vessels. There is a significant difference in densities between the two vascular beds when "bare" varicosities located < 1 micron from the medial smooth muscle are compared. The second-order branch of the ear artery has an average of 18 bare varicosities per 500-micron circumference, and the corresponding cerebral vessel has only 2.8 bare varicosities per 500-micron circumference. The mean bare varicosity-smooth muscle cell separation (mean +/- SEM) is significantly (P < .05) less in the ear (1.18 +/- 0.06 microns) than in the cerebral arteries (4.95 +/- 0.23 microns). This is true of all vessels studied. Fifty-nine percent of the bare varicosities in the ear arteries are < 1 micron from the smooth muscle cells, and 1.2% are more distant than 5 microns. These values for cerebral vessels are 9.5% and 37%, respectively. In the ear vessels, 25% of the bare varicosities make close neuromuscular contact (within 500 nm of the smooth muscle), whereas only 3% do so in cerebral vessels; in cerebral compared with ear vessels, the percentage becomes significantly less with branching. These structural features of brain vessels, taken together with the lower sensitivity to and the diminished capacity to respond to norepinephrine, probably account for their weak neurogenic control. The results indicate that the cerebral circulation of the rabbit receives a sympathetic innervation that is relatively ineffective in altering cerebrovascular tone.

Intrathoracic spatial location of specified coronary segments on the normal human heart. Applications in quantitative arteriography, assessment of regional risk and contraction, and anatomic display.

The clinically important coronary segmental anatomy has been described in a format useful for quantitative analysis and standardized display. We have determined the intrathoracic location and course of each of the 23 coronary artery segments and branches commonly used for clinical description of disease. Measurements were averaged from perpendicular angiographic view-pairs in 37 patients with normal-sized hearts. Each segment or branch is described by several points along its course; each point is specified in polar coordinates as the radial distance from the principal coronary ostium and by angles about the patient, corresponding to those describing rotation in c-arm radiographic systems. This computer-assisted measurement method is accurate to within +/- 0.2 cm (SD) and +/- 2 degrees in phantom studies. Coronary segment location among a group of normal-sized hearts can be specified to within +/- 1.0 cm (SD). For example, the left anterior descending coronary artery segment at the apex of the heart is 12.2 +/- 1.0 cm from the left coronary ostium, 32 +/- 4 degrees to the left of the anterioposterior axis, and at 46 +/- 7 degrees of caudal angulation. There are several clinically important applications of this new knowledge. First, this anatomic format provides the basis for estimating regional myocardial contraction and the relative size of the myocardial region at risk from a given arterial occlusion. Second, precise knowledge of "normal" segment location greatly simplifies the computation of dimensional correction factors for quantitative arteriography. Third, viewing angles most appropriate for videodensitometric assessment of lesion lumen area may be computed from these data. The theoretical basis and numerical values needed for most of the above estimates are provided. Finally, a computer program has been written to generate a three-dimensional tree-branch vascular model from these anatomic locations. This easily used interactive program aids in teaching coronary angiographic anatomy and, of importance, permits selection of viewing angles that "best" visualize the traditionally difficult parts of the coronary tree.

Lumen diameter of normal human coronary arteries. Influence of age, sex, anatomic variation, and left ventricular hypertrophy or dilation.

BACKGROUND: Precise knowledge of the expected "normal" lumen diameter at a given coronary anatomic location is a first step toward developing a quantitative estimate of coronary disease severity that could be more useful than the traditional "percent stenosis." METHODS AND RESULTS: Eighty-three arteriograms were carefully selected from among 9,160 consecutive studies for their smooth lumen borders indicating freedom from atherosclerotic disease. Of these, 60 men and 10 women had no abnormalities of cardiac function, seven men had idiopathic dilated cardiomyopathy, and six men had left ventricular hypertrophy associated with significant aortic stenosis. Lumen diameter was measured at 96 points in 32 defined coronary segments or major branches. Measurements were scaled to the catheter, corrected for imaging distortion, and had a mean repeat measurement error of 0.12 mm. When sex, anatomic dominance, and branch length were accounted for, normal lumen diameter at each of the standard anatomic points could usually be specified with a population variance of +/- 0.6 mm or less (SD) and coefficient of variation of less than 0.25 (SD/mean). For example, the left main artery measured 4.5 +/- 0.5 mm, the proximal left anterior descending coronary artery (LAD) 3.7 +/- 0.4 mm, and the distal LAD 1.9 +/- 0.4 mm. For the LAD, lumen diameter was not affected by anatomic dominance (right versus left), but for the right coronary artery, proximal diameter varied between 3.9 +/- 0.6 and 2.8 +/- 0.5 mm (p less than 0.01) and for the left circumflex, between 3.4 +/- 0.5 and 4.2 +/- 0.6 mm (p less than 0.01). Women had smaller epicardial arterial diameter than men (-9%; p less than 0.001), even after normalization for body surface area (p less than 0.01). Branch artery caliber was unaffected by the anatomic dominance but increased with branch length, expressed as a fraction of the origin-to-apex distance (p less than 0.001). Lumen diameter was not affected by age or by vessel tortuosity but was significantly increased among men with left ventricular hypertrophy (+ 17%; p less than 0.001) or dilated cardiomyopathy (+ 12%; p less than 0.001). CONCLUSIONS: This is a reference normal data set against which to compare lumen dimensions in various pathological states. It should be of particular value in the investigation of diffuse atherosclerotic disease.