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)

The endotheliums of rabbit corneas were perfused in an in vitro perfusion specular microscope up to 3 hr with solutions varying in pH from 3.5 to 10.0. Corneal thickness was monitored throughout the experiment, and at appropriate times the corneas were prepared for SEM and TEM. Analysis of the corneal thickness data and interpretation of the electron micrographs reveals that outside of the pH range of 6.5 to 8.5, structural and functional alterations occur. Direct cellular damage, as well as disruption of junctional complexes, lead to a breakdown in the barrier function of the corneal endothelium. The extent of this breakdown is dependent upon both the magnitude of the pH change and the exposure time. Further experiments on banked human eyes support this finding.
 ...
PMID:The pH tolerance of rabbit and human corneal endothelium. 3 76

Colloidal gold provides an immuno- and cytochemical marker suitable both for TEM and SEM. Various parameters involved in the preparation and stability of gold markers of various sizes and of probes have been reviewed and modifications in methodology suggested based on a study of factors affecting the performance of the gold marker system. In particular, dependence of protein adsorption on pH conditions correlating with protein pI is further confirmed. Presence of bioactive protein in gold probes is demonstrated and quantitated by radioassay (125I) and agglutination procedures.
 ...
PMID:Colloidal gold probes--a further evaluation. 4 69

The differentiation of the presumptive neural plate, the neural plate and the neural tube have been investigated in the chick embryo by SEM, TEM and histochemical techniques. The relationship of these tissues to neighbouring structures, including extracellular materials, has also been studied. When SEM micrographs of primitive streak stage embryos were examined in stereo, it was found that cells which had been invaginating at the time of fixation were similar in shape to fibroblasts migrating in vitro. It was concluded that SEM stereo pairs could provide evidence about the mode and direction of cell migration. Many more mid-bodies have been found associated with the developing neural tissue than with the lateral ectoderm. It was found possible to recognise mid-bodies not only by TEM but also by SEM. It is therefore proposed that SEM montages may be used for assessing which regions of a tissue have recently undergone extensive mitosis. The beads on the specialised threads seen in the early stages of development are now considered to be formed from mid-bodies. Similar, but unbeaded threads have been described which span the gap between the neural folds just prior to the dorsal closure of the neural tube and it seems probably that these threads help to close the neural tube. It is suggested that the beaded threads arise by incomplete separation of two daughter cells at mitosis, whereas the unbeaded threads form by outgrowth of cell processes.
 ...
PMID:Differentiation of the neural plate and neural tube in the young chick embryo. A study by scanning and transmission electron microscopy. 5 84

The Gomori aldehyde-fuchsin (AF) method for selective staining of neurosecretory substance (NSS) has been adapted to tissue previously prepared for both scanning and transmission electron microscopy (SEM/TEM). The procedure results in precise correlation of light microscopic (LM) histochemistry with SEM/TEM of the same tissue.
 ...
PMID:Demonstration of neurosecretory substance in previously scanned specimens: adaptation of the Gomori aldehyde-fuchsin method for correlative SEM/TEM/LM histochemistry. 8 9

Normal and denatured polytene chromosomes from Drosophila were compared by light, transmission (TEM) and scanning (SEM) electron microscopy, under different conditions of pretreatment, fixation and specimen preparation. Apart from variations in contrast, acid-alcohol squashes of normal chromosomes were quite comparable in terms of resolution and image quality, regardless of mode of visualization, i.e. stained, unstained, phase contrast, etc. These chromosomes do not appear markedly different from the unfixed or "native" chromosomes isolated by other workers. Thus at the light microscope level at least, any soluble components extracted by acid-alcohol fixation seem to play minor structural roles only. SEM examination of similar squash preparations provided useful topographic views of selected chromosome regions, particularly in favourable spreads where metal coating and tilt angles were optimized. Information on the internal organization of polytene chromosomes was sought by subjecting isolated preparations to alkali-urea denaturation. Under these conditions, chromosomes gradually extend laterally to give rise to lampbrush-like structures, remarkably similar to the meiotic chromosomes of amphibian oocytes. This effect is at least partially reversed by return of alkali-urea treated preparations to physiological Ringer solution, where chromosomes contract again and near-normal banding patterns are re-established. It is suggested that apart from bulk differences due to polyteny, the basic structure of polytene chromosomes and true lampbrush chromosomes may be rather similar.
 ...
PMID:The morphology of normal and denatured polytene chromosomes from Drosophila melanogaster. 9 84

The cells of a patient with chronic lymphocytic leukaemia (CLL) showed a peculiar phenomenon of nuclear blebbing and nuclear extrusion, observed by transmission (TEM) and scanning (SEM) electron microscopy. Protein synthesis of the lymphocytes was 3 times higher than that of cells of other 3 patients with CLL, but was lower than the synthesis of cells from a patient with acute lymphoblastic leukaemia (ALL). Similar results were observed when RNA synthesizing activity of the cells was examined. On the other hand, thymidine incorporation proceeded in a similar rate in the patient's and the ALL lymphocytes, whereas in those CLL patients it was merely detected. The morphological findings and the synthesizing activities of the cells suggest that the patient's disease represents an intermediate form between CLL and ALL.
 ...
PMID:Ultrastructural and functional studied on the lymphocytes of a patient with chronic lymphocytic leukaemia and nuclear extrusion. 9 56

The urinary bladder of Bufo marinus excretes H+ and NH+4, and the H+ excretion is increased when the animal is placed in metabolic acidosis. The mitochondria-rich (MR) cells mediate the H+ excretion by the bladder. The purpose of this study was to determine if there is a change in MR cells of the bladder during metabolic acidosis. Bladders from normal toads and from toads that had been placed in metabolic acidosis were used. The bladders were mounted between plastic chambers and H+ excretion measured. The bladder was then fixed and prepared for scanning (SEM) and transmission (TEM) electron micrograph studies. SEM's at low magnification were used to count the various cell types and the TEM's were used to confirm the different cell types. Fields were randomly selected and a total of 2500 cells counted in each group. The bladders from toads in metabolic acidosis had a consistently higher ratio of MR cells to granular cell than did the normal bladders. These results indicate that during metabolic acidosis there is an increased number of MR cells in the bladder, and this increased the bladder's capacity to excrete H+.
 ...
PMID:Cellular changes in the toad urinary bladder in response to metabolic acidosis. 9 69

Changes in liver sinusoids following fractionated irradiation were studied by use of TEM and SEM. Rats received telecobalt-irradiation of their liver regions in daily doses of 500 r for 9 days, a total dose of 4500 r. One day after the end of the irradiation series the fine structure of hepatocytes was almost intact. In SEM the liver sinusoids contained numerous corpuscles, which in TEM were recognized as cellular blebs separated from endothelial cells. 8 days after irradiation small foci of necrotic hepatocytes could be visualized. Instead of complexes of small fenestrations (sieve plates) the endothelial cells contained striking round or oval holes in their tenuous processes. After 120 days small groups of hepatocytes with alterated fine structure of their organelles and some necrotic parenchyma cells were still present. Away from these focal necroses the endothelial cells now resembled sinusoidal endothelium in control animals. Fat-storing cells appeared to have multiplied and were enlarged. There was distinct fibrosis only in perisinusoidal spaces. The formation and discharge of electron lucent blebs is discussed as a mechanism compensating for an enhanced uptake of fluid into irradiation injured endothelial cells. In order to form holes in the tenuos processes of endothelial cells a disordered synthetic pattern and the shearing forces of the circulating blood are thought to be necessary. Repair of these intracellular holes may be possible. In rats irradiation induced lesions of the small intrahepatic vessels can be excluded as a cause of the late changes in liver parenchyma cells.
 ...
PMID:[The liver sinusoids in rats following fractionated local telecobalt-irradiation. A transmission and scanning electron microscopic study (author's transl)]. 14 69

Primary mineralization in neoplastic tissue was studied in osteosarcoma, correlating observations obtained by SEM to those found with TEM. The process is characterized by extracellular matrix vesicles, distributed in the matrix between the forming neoplastic cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatite crystals within the vesicles is followed by accumulation of apatite crystals, disappearance of the vesicular membrane and formation of calcospherites and calcified fronts. The process described here in neoplastic tissue is essentially similar to primary calcification in normal calcified tissues.
 ...
PMID:The relationship between extracellular matrix vesicles and calcospherities in primary mineralization of neoplastic bone tissue. TEM and SEM studies on osteosarcoma. 15 92

Seventeen cancers from lung and pleura were studied with scanning, transmission electron, and light microscopy (SEM, TEM and LM). Diffuse mesothelioma mimics bronchioloalveolar carcinoma at LM but shaggy microvilli were found on the cellular surface of the former, and short sprouts densely packed or loosely scattered, on that of the latter. Neolumen formation was found in both. Oat cell carcinoma had a smooth surface with occasional tiny projections and minute surface depressions. The cellular projections of squamous cell carcinoma were quite irregular. Differentiation between diffuse mesothelioma and bronchioloalveolar carcinoma appears feasible with SEM in tissue appropriately fixed either with formaldehyde or glutaraldehyde. The role SEM can play in diagnostic pathology is yet to be explored.
 ...
PMID:A scanning electron microscopic study of diffuse mesothelioma and some lung carcinomas. 19 41


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