Chronological effects of atherogenic diets on the aorta, liver and spleen of rabbits

To investigate the temporal progression of atherogenesis on the aorta and involvement of the monocyte-macrophage system in the liver and spleen, we fed 74 rabbits with high fat (14 or 7 gm+ACU-) and cholesterol (2 and 1+ACU-) diets for 4 to over 24 weeks. Using both light and electron microscopies, we found that the bro-fatty areas on the luminal surface of aortas was spread over along the eding time dependently. The fat deposits also in the liver and spleen worsened pending on the time of feeding the atherogenic diets. Not only nocyte-derived foam cells, but also parenchymatous cells in the liver and leen involved become fat-laden cells. According to these results, we propose at there are three stages: 1) the primary seeding, 2) the intermediate turing and 3) the advanced periods. These periods may play very important les in designing the management and treatment of atherosclerotic patients.

Chronological effects of atherogenic diets on the aorta, liver and spleen of rabbits

To investigate the temporal progression of atherogenesis on the aorta and involvement of the monocyte-macrophage system in the liver and spleen, we fed 74 rabbits with high fat (14 or 7 gm+ACU-) and cholesterol (2 and 1+ACU-) diets for 4 to over 24 weeks. Using both light and electron microscopies, we found that the bro-fatty areas on the luminal surface of aortas was spread over along the eding time dependently. The fat deposits also in the liver and spleen worsened pending on the time of feeding the atherogenic diets. Not only nocyte-derived foam cells, but also parenchymatous cells in the liver and leen involved become fat-laden cells. According to these results, we propose at there are three stages: 1) the primary seeding, 2) the intermediate turing and 3) the advanced periods. These periods may play very important les in designing the management and treatment of atherosclerotic patients.

Morphological Study on the Development of Medial Lamellar Unit in the Wall of Aorta and its Major Branches in Human Fetuses / 대한해부학회지

The structure of the arterial wall is formed and controlled by various hemodynamic factors in the adults and fetuses. Furthermore, recent studies of human fetuses at varying stages confirmed that the number of elastic medial lamellar unit (MLU) increased with age and decreased along it length from arch to lower abdominal aorta. Using human fetuses between 9 to 28 week of development, we traced the change in the number of MLU along the arch of aorta from which 3 major branches, the brachiocephalic trunk, left common carotid artery, left subclavian artery, arose. The number of MLU along the arch of aorta increased with age, but there were regional differences in the increase. Increase in the number of MLU was prominent in the proximal part of the arch before 15 week of development, but in the distal part after 15 week of development. Branch with greater diameter had more MLU. So the brachiocephalic trunk had the most MLU among 3 branches. When compare the sum of number of MLU in one branch (A) and in the arch after origin of branch (B) to the number of MLU in the arch before origin of brahch (C), A+B was always greater than C. This means that the MLU does not form a complete sheet along the aorta and new MLU is added to the wall of branch probably due to shear stress.

Surface features of human aortic atherosclerosis as seen with scanning electron microscopy

Using SEM, we have observed surface structures of atherosclerotic lesions of human aortas obtained from autopsies ranging from 59 to 84 years of age (5 males and 4 females). We have found four major interesting features on the lumenal surface of the aortas: 1) blood cells including leukocytes adhering to the endothelial surface, 2) a de-endothelialized surface showing both elastogenesis and elastolysis, 3) abundant cholesterol-ester crystals in extracellular spaces, and 4) cave-like structures possibly suggesting new capillarization in the thrombotic atherosclerotic plaques. We concluded that SEM has a great value in revealing more interesting surface structures if morphological studies are previously done in detail so that the characteristic shapes can be identified, and perhaps then meaningful interpretations can be made on the mechanism of human atherogenesis.

The effects of aging and atherosclerosis on elastin of human aortas; quantitative analysis of elastin-content and SEM analysis of elastolysis

We have examined 24 human aortas aged 46 ~ 90 years obtained from autopsies. Most exhibited gross lesions of some degree on the lumenal surface. Using hot alkaline treatment (0.1 N NaOH) at 70 ~ 75degreeC for 5 hours, we extracted and quantitated elastin portions from the aortic wall in 3 different segments (UTA = upper thoracic aorta, LTA = lower thoracic aorta, AA = abdominal aorta). We have found UTA had 70.6% +/- 1.39 (SE), LTA 61.6% +/- 1.94 (SE), AA 49.2% +/- 1.84 (SE) elastin respectively based on wet weight. The differences between segments are statistically significant (p < 0.05, 0.025). However, there is no significant correlation between the age of the patients and the relative amounts of elastin in each segment. We have also observed the structure of elastin in the internal elastic lamina (IEL) and tunica media (TM) with SEM (scanning electron microscopy), and discovered that the IEL shows various forms of elastolysis-broken sheets, discontinuity, various sizes of lumps, vesicles, and possible newly formed elastin in the aortic lesions (Song and Roach submitted to YMJ). From these studies we conclude that elastin in the aortic wall remains well balanced quantitatively with age in spite of evidence suggesting vigorous degeneration and regeneration in the atherosclerotic lesions.

Three dimensional structures of pulmonary elastin; airway vs vascular elastin

Elastin is known to occur in the lung parenchyma and pleura as well as in the pulmonary vessels, but no detailed studies of this elastin's linkage between them have been done in three dimensions. For many years we have known that there is abundant elastin in the mammalian lungs, which may be associated with etiology of causing emphysema. We have developed selective casting methods to allow us to determine the location where elastin is found morphologically. The method involves casting either the vasculature via the right ventricle, or the airways via the trachea in the air sacs. Studies of the vasculature were done with the lung inflated to 80% of the vital capacity. The casted lungs were then put in 0.1 N NaOH at 75 degrees C for 48 hours, turning them frequently. THis method removed all non-elastin tissues. The scanning electron microscopy (SEM) was used to reveal the three dimensional pictures of elastin structures from both lung parenchyma and pulmonary vessels. Elastin was seen as fenestrated sheets and some fibers in both the vessels and the airways. Elastin in the two different locations was often interconnected. Studies on 6 dogs, 8 rabbits, and 2 pigs showed no significant species difference at the level of resolution of the SEM, which was used to study the specimens after they had been freeze-dried.

Compartmental analysis of RBC circulation through the rabbit kidney

This experiment involved 12 rabbits of both sexes, weighing 2.1 kg. After anesthesia, the kidneys were exposed, isolated and cannulated in the renal artery, ureter and sometimes in the vein as well. The kidney were perfused through the renal artery with Krebs-Henseleit solution, which were then filtered to be free of particles, gased with 95% O2-5% CO2, and kept at 37 degrees C. We measured RBCs concentrations by means of Coulter Counter in the venous outflow collected, and plotted them against the volume perfused. Using 2 different flow rates, 9 ml/min (group I) and 19 ml/min (group II), we found that the RBCs decreased in a multiexponential decay fashion and a biophysical model for each flow rate was constructed. These models indicated that there were more cell stores (2.20 x 10(10)) in the fast compartment of group II than in group I (1.72 x 10(10)). This difference is not statistically significant, but certainly coincides with urine flow collected from ureter cannula during perfusion. Our present data clearly suggest that in order to clear 99% blood cells out of 10-12 gm rabbit kidneys, at least 3-6 ml of cell free perfusate is required while clearing the whole blood cells out of human kidneys (200-240 gm) may need 600 ml or more. Thus, we recommend that at least 600 ml of perfusate should be used to clear most of the blood cells in the renal vasculature before renal transplantation is performed.

Morphological evidence of pulmonary vascular leakage through gaps observed with casting methods and S.E.M

We have used selective casting methods to separate pulmonary elastin from vascular elastin in the lungs of rabbits, dogs and pigs. The lungs are digested with 0.1 N NaOH at 75 degrees C for 24 approximately 48 hours with frequent turning as the lungs are filled with air to about 80% of the vital capacity prior to the casting which is done at pressure of 20 approximately 50 mmHg. After vascular injections, we saw many small globular bits of casting material well separated from cast vessels and lying in the pulmonary elastin. Surface forces should make the casting material creep along the vessels even if they are not completely filled, so that the spherical shape is the one expected if the case is extruded into the parenchymal space and the air space. We conclude that this suggests that the pulmonary circulation is partially and temporarily 'open' as seen in the spleen and some other organs, rather than a completely 'closed' one as is generally accepted. At least some of these extravasations may be associated with lymphatics, although we have not proved this.

Development of elastin layers in the aortic wall of human fetuses

The presence of elastin layers in the aortic walls of twelve human fetuses was confirmed with scanning electron microscope pictures after hot alkali treatment and histochemical examination. In addition, the number of elastin layers in aortic walls of 5 different segments were compared in fetuses of varying ages. Aldehyde fuchsin stained slides of elastin ascending aortas showed a range between 27 and 55 layers of elastin in fetuses of 8 weeks to 32 weeks. However, in the lower abdominal aortas, elastin layers decreased from 28 to only 3 layers for fetuses of the same age. Furthermore, as elastin layers decreased from ascending aorta to abdominal aorta with the progression of fetal life, similar changes in the elastin lamellae were observed. These results suggest that while aortas grow rapidly in length, the medial elastin thickens slowly, perhaps due to slow development of hydrodynamic forces and pressures. Also the adventitial elastin appears to lose out gradually along the length from ascending aorta to abdominal aorta.

Sluggish Clearance of Red Blood Cells From Microcirculation in Spleen, Cardiac and Skeletal Muscles

In three isolated organs, spleen, cardiac and skeletal muscles, kinetic studies of red cell washout were carried out by using perfusion of the cell-free, oxygenated Ringer's solution. It is found that in each organ there are slow components for red cells to be emptied out from the vascular lumens ranging 30 to 50 minutes as the desaturation half-time. The slowest decay constants (K) are -1.48 X 10(-3) for spleen, -2.33 X 10(-3) for gastrocnemius muscle, and -4.0 X 10(-3) for cardiac muscle.

Work Performance After Thoracic Surgery

Cardio-pulmonary responses to a given step-up exercise test were studied in 43 patients who previously received various thoracic operations such as pleural decortication, one or two segmental resections, right or left upper lobectomy, plombage or pneumonectomy. Fourteen control subjects were also studied for comparison. Following a 30 minute rest, the step-up exercise was performed to heights of 20, 30 and 40cm, in that order, for 8 to 10 min. at each height. During the rest and the steady-state exercise period, the expired gas was collected for a period of 5 minutes for the determinations of the minute volume, the O2 consumption and the CO2 Output. Alveolar gas samples were a1so taken following the expired gas collection. The heart rate and blood pressure were also checked during the rest and immediately after each exercise. Various cardio-pulmonary functions of the patient at rest were little different from those of the control, except the heart rate which tended to be higher in the patient than in the control. Although the work capacity of the patient was lower than in the control, most patients were able to complete the required exercise test. However, in carrying out a given exercise load, the patient groups had a greater minute volume, the respiratory rate, the O2 consumption and the CO2 output as compared to the control, indicating that the mechanical efficiency is considerably lowered in the patient. Of various patient groups, the work performance was most limited in the pneumonectomy group while the group with one or two segmental resections was little affected. It is suggested that the patient with one or two segmental resections may be allowed to engage in physical activity up to 700 kg-m/min or more while those with pneumonectomy should not exert themselves above 500 k-gm/min.