After investigating the compression testing method against a plate type specimen by the cylindrical die as a cold forgeability which, when the history of strain during deformation is linear makes it possible to calculate the stress by the total strain theory, the underwritten facts have been confirmed.(1) The optimum conditions can be gained if a plate type specimen with thickness H, width 2H and radius of curvature of initial bulge profile (3.3∼6.6) H, is compressed by a cylindrical dies.(2) In the test under such a condition if only the tatal strain in height at fracture is measured, the local strain at the part where a crack occurs and the stress can be calculated accurately.
Natural levels of solar UVR were shown to break and alter the spiral structure of Arthrospira ( Spirulina ) platensis (Nordst.) Gomont during winter. However, this phenomenon was not observed during summer at temperatures of ∼30°C. Since little has been documented on the interactive effects of solar UV radiation (UVR; 280–400 nm) and temperature on cyanobacteria, the morphology, photosynthesis, and DNA damage of A. platensis were examined using two radiation treatments (PAR [400–700 nm] and PAB [PAR + UV‐A + UV‐B: 280–700]), three temperatures (15, 22, and 30°C), and three biomass concentrations (100, 160, and 240 mg dwt [dry weight] · L −1 ). UVR caused a breakage of the spiral structure at 15°C and 22°C, but not at 30°C. High PAR levels also induced a significant breakage at 15°C and 22°C, but only at low biomass densities, and to lesser extent when compared with the PAB treatment. A. platensis was able to alter its spiral structure by increasing helix tightness at the highest temperature tested. The photochemical efficiency was depressed to undetectable levels at 15°C but was relatively high at 30°C even under the treatment with UVR in 8 h. At 30°C, UVR led to 93%–97% less DNA damage when compared with 15°C after 8 h of exposure. UV‐absorbing compounds were determined as negligible at all light and temperature combinations. The possible mechanisms for the temperature‐dependent effects of UVR on this organism are discussed in this paper.
We succeeded in producing cerebral atherosclerotic lesions in hypertensive rabbits fed with cholesterol. To examine the location and progression of atherosclerotic lesions, frontal dissection of cerebral arteries (vertebral arteries, basilar artery and posterior cerebral arteries) was performed and thus an overall view of these vascular luminal surface was acquired. Initial atherosclerotic lesions developed at the Y-bifurcation of arteries (from basilar artery to right and left posterior cerebral arteries) and confluent portion of arteries (from right and left vertebral arteries to basilar artery). Lesions observed by the scanning electron microscopy showed passing figures of macrophages and protrusion or distortion of endothelial cell configurations. These features are almost consistent with those described in aortic lesions. The location of lesion at the arterial Y-bifurcation made reminiscent of that in human cerebral atherosclerosis. In addition, it has been said that a peculiar form of eddies developes at Y-bifurcation of artery; observations on the normal rabbit cerebral artery disclosed that these vascular Y-bifurcation and confluent portions correspond to the turning and confluent points of endothelial arrangement of the corresponding arteries respectively. From these observations it was concluded that these specialities in blood stream and endothelial arrangement may relate to atherogenesis of the cerebral arteries.
Abstract: Atherosclerosis is a chronic inflammatory process affecting mainly elastic and muscular arteries. Although small arteries and arterioles are usually spared, atherosclerosis can occur in these small vasculatures for a very short period. Here we report a case of atherosclerosis‐like lesions that occurred in a transplanted kidney showing acute accelerated rejection in a 43‐year‐old man. Histologically, biopsy specimens at 14 and 28 days and nephrectomy material at 52 days post‐transplantation showed atherosclerosis‐like lesions in various‐sized arteries. The lesions were characterized by the intimal infiltration of inflammatory cells, including foamy macrophages and a variable number of T‐lymphocytes, with smooth muscle cell proliferation. Immunohistochemistry disclosed that the foam cells expressing CD68 contained oxidized LDL. In addition, apolipoprotein(a) (Lp(a)), another major atherogenic lipoprotein, was found in the intimal smooth muscle layer, suggesting that Lp(a) induced smooth muscle cell proliferation in the rejected kidney as a mechanism of atherosclerosis. This case shows that immunoinflammatory reactions during a relatively short period can mimic the chronic atherosclerotic process even in small arteries and arterioles. Furthermore, the deposition of atherogenic lipoproteins, Lp(a) and oxidized LDL in lesions of rejected tissue present an analogy between vascular rejection in transplanted kidney and atherosclerosis.
Vascular endothelial growth factor (VEGF) is an important mediator in maintaining normal kidney functions. In addition, several lines of evidence suggest that upregulation of VEGF in glomeruli may be associated with or cause renal dysfunction such as diabetic nephropathy. For elucidation of the pathologic consequences of high levels of VEGF in glomeruli, transgenic (Tg) rabbits that express human VEGF(165) isoform in both kidney and liver under the control of the human alpha-1-antitrypsin promoter were generated and characterized. With the use of heterozygous Tg rabbits and their littermates aged 8 to 55 wk, renal functions and structures were investigated. Compared with control rabbits, Tg rabbits exhibited progressive proteinuria with increased GFR at the early stage and decreased GFR at the later stage. Histologic examinations revealed that Tg rabbit kidneys were characterized by considerable glomerular hypertrophy as a result of increased proliferation of both glomerular capillaries and mesangial cells accompanied by prominent podocyte hypertrophy. With increasing age starting from 20 wk, Tg rabbit kidneys showed prominent formation of microaneurysms and capillary proliferation at the vascular pole area. At a later stage (55 wk), many glomeruli showed sclerosis and tuft collapse with the formation of glomerular cysts on a background of tubular atrophy and interstitial fibrosis. This study provides the first evidence that increased expression of VEGF in glomeruli directly causes the glomerular hypertrophy that is associated with proteinuria, suggesting that VEGF exerts multiple effects on the glomerular pathophysiologic processes.
The purpose of this paper is to report the histopathological findings and quantitative evaluation of glomerular enlargement in the kidney from patients with cyanotic congenital heart disease. Comparison between morphological changes of kidneys and certain clinical findings was also attempted. Material and Method Histological examination and histometrical measurements of glomerular size were performed in thirty-six kidneys from congenital cyanotic heart disease. Included were' 25 patients with tetralogy of Fallot, 3 with transposition of great vessels, 3 with truncus arteriosus and 5 with miscellaneous cardiac malformations with cyanosis. They ranged in age from 7 days to 29 years, with an average of 8.5 years. Thirty-three control cases were selected, at random from the autopsy files, as fulfilling the following criteria of "normality" : the absence of congenital heart disease; the presence of both kidneys without significant rend disease: the absence of congestive heart failure and blood dyscrasia. These cases were chosen to cover the age range from newborn to 27 years with an average age of 9.1 years. Two sections of each kidney were reviewed. Tissues were fixed in 10 per cent formalin and embedded in paraffin. All preparations were stained with hematoxylin and eosin and peridic acid-Schiff. Technique of Measurement: A measure of average glomerular size was performed in each case by means of an optical micrometer. Two linear measurements were made for each of 100 glomeruli with apparent vascular poles. The first measurement "A" was the maximum distance across Bowman's capsule : the second, "B", the maximum distance across Bowman's capsule at right angles to the first measurement. A cross-sectional glomerular area was calculated by 1/4πAB. For statistical analysis, P≤0.01 was considered to be significant.
Human aortic endothelial cells and smooth muscle cells (SMCs) were cultured at various ambient pressures and their properties were examined. The following results were obtained. 1) Endothelial cells were damaged when cultured at higher ambient pressures of 80 and 160 mmHg. This left cellular islands with central confluence showing no evident growth because of strong contact inhibition. 2) Aortic endothelial cells released high levels of prostacyclin, with significantly elevated release at higher ambient pressures, while intimal SMCs released a small amount of prostacyclin, and medial SMCs a minimal amount. 3) Prostacyclin release by aortic endothelial cells was inhibited in the presence of low concentrations of linoleic acid hydroperoxide (LAHO). Intimal and medial SMCs, however, showed no LAHO inhibition. These results indicate that the properties of both endothelial cells and SMCs vary according to in vitro and probably in vivo conditions. Their specific roles in the pathogenesis of various vascular disorders including atherosclerosis should be carefully considered.
