Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vascular dysmorphogenesis is usually investigated by invasive microdissection or time-consuming reconstruction of serial sections. Stereomicroangiography (SMA) was used for detection and analysis of vascular abnormalities in a murine trisomy 13 model demonstrating pulmonary atresia. Twenty-two litters from doubly heterozygous Robertsonian translocation Rb(6.13)3Rma/Rb(5.13)70Lub male matings to NMRI females were studied. Embryos (13-17 days gestation) were prepared by umbilical vein perfusion with buffered fixative and umbilical artery perfusion with 5% AgNO3. After immersion fixation specimens were infiltrated with paraffin, mounted on stubs, and stereoradiographed at multiple angles. Transverse serial sections were prepared of the thoracic area. Thoracic vascular morphology was satisfactorily imaged and trisomy 13 embryos were correctly distinguished from normals in 105 of 120 embryos (87.5%). When independent SMA and histologic interpretations were compared anomalous vasculature was correctly identified in all 27 trisomic embryos and one control, and falsely interpreted in one normal embryo. Normal vascular morphology was demonstrated in the remaining 76 normal embryos. Separate SEM evaluation of five microdissected hearts from nontrisomic embryos following this perfusion schedule showed normal distension of the ventricular cavity and metallic silver deposition on the surface and at junctions of endocardial cells. Light microscopy revealed silver staining at the endothelial surface and within the endocardial cushions. SMA accurately records embryonic vascular morphology for rapid screening of viable embryos.
 ...
PMID:Stereomicroangiography in embryologic and teratologic investigation. 376 70

Two human renal biopsies containing glomerular amyloid deposits organized into spicular formations (spicular amyloid) were studied by scanning electron microscopy following removal of the cellular components (acellular SEM). Following SEM studies, portions of the same acellular tissue were embedded in paraffin and plastic for light microscopy and transmission electron microscopy, respectively. Spicular deposits by acellular SEM appear as tapering conical formations interconnected by a delicate branching network of fibrils, which imparts a higher degree of organization than previously appreciated by two-dimensional LM and TEM. Silver stains of paraffin- and plastic-embedded acellular tissue showed persistence of argyrophilia in spicular deposits, while acellular TEM showed that the spicules appeared comprised "purely" of amyloid fibrils without visible contaminating material. We conclude that the argyrophilia of spicular amyloid is an inherent feature of the parallel organization of fibrils rather than a result of incorporation of glomerular basement membrane or cell components and that spicular amyloid deposits have a higher degree of organization than is apparent by two-dimensional studies.
 ...
PMID:Acellular scanning electron microscopy of spicular renal amyloidosis. 382 57

Since specular microscopy of the cornea offers the opportunity to observe and measure cells in vivo without any outside interference this method forms an unrivalled basis for estimation of tissue shrinkage during various preparatory methods. Therefore a study was performed with the purpose of evaluating the degree of artifacts in each preparatory step from the living tissue "in vivo" to the final SEM specimen. The study was performed on rabbit corneas, the endothelium serving as measuring target. The in vivo state was recorded by specular microscopy. Unfixed corneas were studied by light microscopy unstained and stained by alizarin red S or silver nitrate. Fixation was performed intracamerally with 1.5% glutaraldehyde (Gla) by a pH, osmolarity, viscosity and intraocular pressure identical with the physiological values of rabbit eyes. Fixation was completed by immersion in 2.5% Gla for 1/2 h. Gla-fixed corneas were evaluated as above before osmification. Dehydration was performed either by graded acetone, by acetone in a gradient-free system, both followed by critical point drying (CPD). At all steps cells were counted using the same reference frame. The number of cells/mm2 was estimated and statistical analysis showed a shrinkage of 22 per cent (area) in unfixed tissue, 26 per cent (area) in normally dehydrated tissue and 37 per cent (area) in gradient free dehydrated tissue processed for SEM.
 ...
PMID:Shrinkage in preparatory steps for SEM. A study on rabbit corneal endothelium. 616 7

The endothelium of the central ear artery of an anesthetized rabbit was damaged by placing artery forceps on the ear over the vessel for 30 min. After removal of the forceps, blood was allowed to flow through the injured vessel for 30 min. Blood flow was then stopped, blood was washed out of the artery in situ and initial fixation with 1% glutaraldehyde was begun. Specimens of the vessel containing the damaged region were postfixed in 3% cacodylate buffered glutaraldehyde and prepared for SEM examination after methenamine silver staining or following post fixation with osmium. Backscattered electron imaging (BEI) of silver stained specimens with inverted signal polarity showed "black" endothelial nuclei similar to darkly stained nuclei of conventional light microscope slide preparations. Secondary electron imaging (SEI) of corresponding sites stained with silver also showed endothelial nuclei. An interruption of the normal pattern of nuclei indicated a detached area of endothelium where subendothelium was exposed. Platelets were observed adhering to the surface of the exposed subendothelium. Injury to the endothelium was seen more readily in silver stained preparations as voids in the nuclear pattern as compared with conventional SEI preparations, postfixed with osmium, which did not show well defined nuclei.
 ...
PMID:Backscattered electron imaging to visualize arterial endothelial detachment in the scanning electron microscope. 619 30

Whole retinae of 4- to 10-day-old chick and quail embryos were spread on membrane filters and kept in culture for up to 4 days. Axon growth during culture was demonstrated by silver staining, anterograde labeling of fibers with RITC, time-lapse recording, and SEM. Fiber growth was observed in specimens from chick embryos up to 7 days old, with a growth maximum at E6 and from quail embryos up to E6 with the maximum at E5. Newly growing axons followed the optic fiber pattern already existing and, like axons in vivo, grew predominantly toward the optic fissure. Directional and orientational adaptation of newly growing axons to the preexisting fibers increased with the donor age. Retinae from donors up to E5 in chick and up to E4 in quail showed a high proportion of axons which crossed the optic fissure during the culture period and invaded the opposite retinal fiber layer. These fibers showed a correct radial orientation while growing in the opposite direction to normal. Likewise, in cultures from these young donors some fibers grew out initially in the diametrically opposite direction to normal toward the tissue periphery. Since all of the wrongly directed axons grew at the same rate as normal and adapted correctly to the already formed axon pattern, this suggests independent signals for the direction and orientation of growing fibers. Treatment of mounted retinae with collagenase or trypsin removed the vitreal retinal surface, leaving the existing axon pattern intact. Subsequently, new axons grew profusely in culture, but lost both their orientational and directional characteristics.
 ...
PMID:Axon growth in embryonic chick and quail retinal whole mounts in vitro. 620 Mar 72

One-kidney, one clip (1K1C) and two-kidney, one clip (2K1C) Goldblatt hypertension was produced in rats by placing 0.30, 0.25, or 0.20 mm silver clips on the left renal artery. Mean arterial pressure (MAP) and plasma renin activity (PRA) were measured in conscious rats 24 to 28 days after clipping. The MAP in control rats (n = 38) was 116 +/- 1 mm Hg (mean +/- SEM). The 0.30, 0.25, and 0.20 mm clips produced MAPs of 133 +/- 2, 161 +/- 5, and 189 +/- 5 mm Hg, respectively, in 1K1C rats, and 123 +/- 2, 129 +/- 3, and 172 +/- 5 mm Hg in 2K1C rats (n = 17-20). When 1K1C and 2K1C groups were compared, MAP was significantly greater in 1K1C rats at all clip sizes. No treatment group's PRA was different than control (4.8 +/- 0.4 ng AI/ml/hr), except for the 0.20 mm 2K1C rats (16.2 +/- 3.1 ng AI/ml/hr). Renal artery pressure (RAP) was measured in another series of experiments and was not different from control in all but the 0.20 mm 1K1C rats. With identical clip sizes, 2K1C rats showed smaller pressure gradients than 1K1C across the clips: 0.30 mm, 8.5 +/- 1.7 vs 10.7 +/- 1.9 mm Hg; 0.25 mm, 16.5 +/- 1.2 vs 42.1 +/- 7.5 mm Hg; 0.20 mm, 51 +/- 5.3 vs 79.1 +/- 5.7 mm Hg (n = 8-12). Therefore, both the increase in MAP and the pressure gradient across the clip were greater in the 1K1C rats at every clip size.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of graded renal artery constriction on blood pressure, renal artery pressure, and plasma renin activity in Goldblatt hypertension. 636 82

Previous studies on cholesterol-induced sudanophilic lesions in rabbit aortas showed that the earliest lesions were periorificial with the greatest involvement distal to branch sites. In order to determine if there is a relationship between endothelial cell morphology and the regional differences in susceptibility to atherosclerosis we compared cell morphology distal to several aortic ostia and away from ostia. We examined the en face morphology of the intimal surface. Vascular casts were made of silver stained normal aortae. The surface was micrographed by SEM. Cell outlines were entered into a computer to calculate three parameters: the cell orientation index which indicates the cell shape, the en face cell area, and the distance between centers index which gives the position of the center of area with respect to the center of a longitudinal axis drawn through the cell. Differences were found between the region distal to branch sites and the region away from branch sites. Differences were also found between the regions distal to different branch sites. The complex variation of morphology led to no conclusive relationship between endothelial cell morphology and atherogenesis in the non-cholesterol-fed rabbit.
 ...
PMID:Relationship between aortic endothelial cell morphology and atherosclerosis in rabbits. 664 52

In this study the time necessary for the increase of the secretory cells in the middle ear mucosa was investigated by EM and SEM and by histochemical observation of the secretory cells. The first experiment revealed that a minimum of six to seven days was required for the renewal of the columnar cytoarchitecture after the exposure to silver protein solution. In the next experiment 35 guinea pigs were subjected to tubal obstruction. Columnar metaplasia was found in one case sacrificed after the third month, and gland formations without myoepithelial cells and nerve endings were seen in those after the fourth month. In an additional experiment, since the frontal sinus of the dogs is simple and pneumatized, duct obstruction was performed. Slight epithelial change and accumulation of glue-like thick mucus, which was negative in culture, was found in all four cases after three months. In one of the two cases with obstruction for four months, typical exophthalmus in the pseduostratified epithelium with an increase in secretory cells or cuboidal epithelium with nonciliated cells was demonstrated.
 ...
PMID:Epithelial changes in or of the middle ear mucoperiosteum. An experimental study. 677 15

The neural retina of avian embryos was spread on a membrane filter and cut in any desired orientation. Strips cut across the retina of 4- to 7-day chick or 3- to 6-day quail embryos were explanted onto collagen gels. Vigorous neurite outgrowth was seen for about 3 days, by which time many neurites were 3 mm long. Horseradish peroxidase (HRP) labeling showed that the cells producing the neurites were large and formed a layer near the inner limiting membrane, indicating that the neurites in vitro were axons of retinal ganglion cells. The size of the neurite population and the regions from which neurites emerged varied with the donor age, while most neurites sprouted from the side of the explant formerly closest to the optic fissure. This pattern closely resembled that of axon growth in the normal retina, as revealed by SEM, silver staining, and HRP labeling. Mitotic inhibitors (Ara-C and FUdR) did not alter the neurite outgrowth. Pretreatment of retinae with trypsin or collagenase did not disorganize axons at the time of explanation, but tended to equalize neurite emergence on each side of the retinal strips. We suggest that microenvironmental factors, especially the enzyme-labile inner limiting membrane, are important for axon guidance in the retina.
 ...
PMID:Oriented axon outgrowth from avian embryonic retinae in culture. 682 32

In anesthetized dogs, a silver wire electrode was inserted into the lumen of the circumflex coronary artery (LCX) and myocardial infarction was produced by a temporary 90-minute occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion. Four days later while in the ambulatory state, a 150 microA current was applied to the intimal surface of the LCX of saline (n = 10) and bretylium (n = 10) treated animals. Intimal injury and coronary thrombosis produced ST segment changes at 138 +/- 39 minutes (chi +/- SEM), followed by premature ventricular beats (at 142 +/- 37 minutes), ventricular tachycardia (at 156 +/- 49 minutes), and ventricular fibrillation (at 163 +/- 51 minutes) in 9 of 10 saline-treated animals. In bretylium-treated animals, ST segment changes appeared at 128 +/- 35 minutes, with six animals surviving for 24 hours (p less than 0.03 vs saline). LAD infarction was present in both saline (14.1 +/- 2.3%) and bretylium (15.1 +/- 2.1% of left ventricle) treated animals with only bretylium-treated animals developing LCX infarcts (16.1 +/- 2.1%). Bretylium prevents ventricular fibrillation (VF) resulting from ischemia at a site distant to prior myocardial infarction in the conscious dog and deserves further attention as a potential antifibrillatory agent for prevention of sudden coronary death in man.
 ...
PMID:Prevention of ventricular fibrillation by bretylium in a conscious canine model of sudden coronary death. 684 13


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>