Biomedical subjects
Publications and source records attributed to G T Simon.
A freeze dried embedding procedure is described and used to study the extracellular cartilage matrix of the epiphyseal growth plate. This method provides improved fine structural preservation of the extracellular matrix over conventional fixation and appears comparable to that attained by freeze substitution. The trabecular networks of expanded proteoglycan filaments are illustrated in stereo-images.
Skin biopsy specimens from 43 patients with established mycosis fungoides (MF) and 28 with non-MF lymphoid skin infiltrations were studied by transmission electron microscopy. The nuclear contour index (NCI) of infiltrating lymphoid cells was obtained by means of a Zeiss Videoplan computer and measuring tablet. Classification of the material into MF and non-MF groups was done according to the diagnostic criteria used by McNutt et al. (1980, 1981) and Meijer et al. (1980); this study evaluates the usefulness of these previously published criteria based on quantitative electron microscopy. Statistical analysis confirmed that the mean NCI (MNCI) of the lymphoid cells of patients with MF is significantly greater than that in patients with other lymphoid infiltrates (P less than 0.001). However, all published diagnostic criteria (McNutt et al., 1980, 1981, and Meijer et al., 1980) tested in the authors' larger patient population yielded lower sensitivity than has been reported. The diagnostic criteria based on values of MNCI, percentage of lymphoid cells with NCI greater than 7, and percentage of lymphoid cells with nuclear profile area of greater than 30 microns2 reported by McNutt et al. (1981) appear to be better than others, and provide the highest sensitivity rate, which is in the range of 44% to 47%. There were no false-positive findings. It was concluded that the use of ultrastructural morphometry according to the techniques and diagnostic criteria of McNutt et al. (1981) is useful in the diagnosis of MF.
We have investigated two cases of chronic eosinophilic pneumonia using the electron microscope. The alveolar septa were thickened due to edema and an infiltrate of numerous mononuclear cells and eosinophils, with a few lymphocytes and occasional plasma cells. Macrophages were often located close to eosinophils and extracellular eosinophilic granules. Occasional eosinophilic granules were observed in the cytoplasm of mononuclear cells. The most striking finding was the presence of distinctive elongated, narrow, tubular inclusions in the cytoplasm of several of the mononuclear cells. These inclusions presented complex curved profiles which sometimes terminated in small, dilated, dense vesicles. Some of the narrow tubular sections of the inclusions presented a pentalaminar structure. Elsewhere, the tubular structures showed localized globular dilatations which contained granular material. Elongated strands of electron-dense material, identical to that forming the intracytoplasmic inclusions, were also located extracellularly, between adjacent mononuclear cells and between mononuclear cells and eosinophils. These inclusions are considered to be the product of phagocytosis of cellular debris and to be related to phagolysosomes rather than to Birbeck granules.
Most assays that measure platelet associated IgG (PAIgG) relate the IgG associated with the test platelets to the platelet count. This could lead to a systematic error if platelet fragments were present in the washed platelet sample but not counted. To address this issue, we studied platelets from patients with idiopathic thrombocytopenic purpura (ITP), thrombocytopenia complicating cardiopulmonary bypass, and laboratory synthesized platelet fragments (freeze-thawed) using electron microscopy. Scanning electron microscopic (SEM) examination of the platelet samples demonstrated appreciable numbers of fragments only in the freeze-thawed specimens. Yet, 'fragments' could be seen in all specimens using transmission electron microscopy (TEM). Most of these 'fragments' proved to be artefacts: we found that the ratio of 'fragments' to intact platelets observed in the TEM specimens was similar to the estimated ratio of 'fragments' to platelets that would have been generated had the specimens been sectioned at 90 degrees to the plane of the actual section. Platelets labelled with the membrane label 125I-iodosulfanilic acid were fragmented by repetitive freeze-thawing. Measurement of pellet radioactivity following washing indicated that the fragments were lost during the washing procedure. These studies indicate that elevated levels of platelet associated IgG in ITP do not represent artefacts due to contamination of the test platelets by platelet fragments.
Numerous cytoplasmic lamellar bodies were seen in many cell types in an open lung biopsy from a patient on amiodarone therapy. These membrane-bound lamellar bodies were characterized by distinct, concentric parallel membranes and peripheral granular densities. Their morphology and distribution suggest a metabolic disorder of phospholipid degradation induced by this drug. The differential diagnosis of lamellar body accumulation in the lung is discussed. This case emphasizes the desirability for ultrastructural study of lung biopsies in such potentially reversible lung disease.
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1. A case of osteochondroma of the temporomandibular joint simulating a unilateral condylar hyperplasia is presented. 2. The need to divide the zygomatic arch to facilitate removal of large tumors is noted. 3. The removal of the growth resulted in normal functioning of the jaws with the disappearance of the features of unilateral hyperplasia. 4. Occlusal grinding is often necessary to correct the compensatory occlusal adjustment that occurs with the rotation of the mandible in these lesions. 5. The possibility of the presence of a tumor must be kept in mind when patients present with symptoms of unilateral condylar hyperplasia.
Using electron microscopy radioautography, the deposition of intravenously administered iron in the duodenal epithelium was studied in normal mice, iron-overloaded and iron-deficient mice, and in mice with X-linked anemia (gene symbol sla) 4 and 24 hours after injection of 59Fe. The resolution of radioautography with 59Fe was determined with a line source and the distance from the hot line within which half of the grains fell (HD value) was 1650 A. In normal, iron-overloaded, and sla mice, radioiron was localized in the undifferentiated crypt cells at 4 hours and in the absorptive cells of the luminal half of the villi, at 24 hours. At both times, the vast majority of the grains was seen over the areas rich in free ribosomes and rough endoplasmic reticulum. In iron-deficient mice, grains were not found at either time. The amount of iron incorporated in the crypt cells was related to the size of the body iron stores. It is postulated that the amount of iron incorporated in the crypt cells is the result of interaction between uptake and return to the blood of the circulating iron. Once the crypt cells have differentiated into absorptive cells, the uptake and recirculation of iron from and to the blood would cease, leaving an amount of "message" iron which determines the absorptive cell's subsequent capacity for iron transfer to the plasma. In sla mice, in spite of tissue iron deficiency, the amount of iron deposited was similar to that of normal mice and markedly increased after treatment of the anemia. The accumulation of iron in the crypt cells may result from the decreased return to the blood of the incorporated circulating iron, due to the postulated deficient iron carrier mechanism in sla, or may be a consequence of increased avidity of the absorptive cells for circulating iron. In either event, the result would be that the absorptive cell receives an inappropriate message with resulting inappropriate absorption of iron.
The degradation of intramuscularly injected autogenic and xenogenic red blood cells are studied with electron microscopy and immunoferritin technique. Autogenic red blood cells are phagocytosed and completely degradated by macrophages within the draining lymph node in a relatively short time. Phagocytosis and initial degradation of xenogeneic red blood cells by macrophages in the draining lymph node are similar; however, portions of the degradation products persist in macrophages as characteristic myelinic-like figures. After 4 days, identical figures appear in large numbers in the adjacent lymphocytes within membrane-bound vacuoles. With the conjugated ferritin antibody technique, these myelinic-like figures are shown to contain antigens of the xenogeneic red blood cells. Subsequently, lymphocytes containing the inclusions are found in the peripheral blood, the marginal zone of the spleen, other lymph nodes, and the bone marrow. As in the draining lymph node the number of plasma cells increases in these organs in areas adjacent to lymphocytes with the inclusions. In a parallel study, uncoated polystyrene spheres injected intramuscularly accumulate and remain localized in macrophages of the draining lymph node. When coated with xenogeneic hemoglobin and membranes, these spheres appear in lymphocytes of the draining lymph node and subsequently in lymphocytes of the blood and spleen.
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Phagocytosis in the bone marrow of rats and rabbits was studied following intravenous injections of colloidal carbon and chicken red blood cells. In both animal species the marrow response to these different foreign particles was quite similar. There was an initial aggregation and degranulation of platelets around the injected particulate matter within the marrow sinuses. Then pseudopods of marrow macrophages appeared in the sinus lumen, forming a web-like structure which trapped and phagocytosed the injected foreign material as well as the platelets. Within the phagosomes of these macrophages, the injected material and platelets were withdrawn into the parenchyma, where degradation or storage occurred. This sequence of events suggests that platelets may play an important role in marrow phagocytosis. The most active cells in marrow phagocytosis are the macrophages. The endothelial cells participated in the phagocytosis of colloidal carbon. The amount of carbon within these cells, however, was small in comparison with that trapped by macrophages. Further, the endothelial cells did not phagocytose chicken red blood cells. These results, being similar to those obtained in lymph, spleen and liver, challenge the concept of the reticuloendothelial system. The term of macrophage system is proposed as a replacement.
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