Biomedical subjects
Publications and source records attributed to G Grant.
The human medulloblastoma cell line, D283 Med, appears to be cytogenetically stable even after passage 121. Stem line number was determined to be 46, with intact X and Y chromosomes. The cell line is characterized by the presence of four marker chromosomes (M1 to M4).
The use of the specular microscope as a noninvasive in vivo method of identifying cholesterol crystals in two cases of crystalline corneal deposits is described. This illustrates the advantage of using the specular microscope under living conditions with a much higher magnification than is obtained with the slit lamp. Attention is drawn to the wider applications of this method.
In order to differentiate clearly red blood cells and their relationship to the corneal endothelium, specular microscopy was performed in patients with hyphaema due to contusion injury. This enabled the clear identification of red blood cells as rounded, umbilicated or flattened spheroidal structures depending on whether they were seen side on or end on. They were seen best in the relief mode lying on the posterior endothelial surface and not infiltrating the corneal endothelium. It also disclosed the presence of subendothelial blebs one to three cells in diameter seen at the level of the corneal mosaic and not in the relief mode. These are probably due to mild oedema following the contusion injury and were distinct from the red blood cells. The corneal endothelial cell count and morphology were similar to that in the other eye when the changes resolved a week or so after the injury.
Examination of the corneal mosaic by the direct mode of specular microscopy and of its posterior surface by the relief mode in three cases of localized keratitis with adjacent clear cornea has enabled us to identify small round white cells. Comparison with the morphology of red blood cells seen in hyphaema indicates that these small round cells are probably lymphocytes since they are fairly uniform in size, spherical but not flattened spheroids and about the same size as or a little larger than red blood cells. These cells are present on the posterior surface of the corneal endothelium but could not be seen infiltrating beneath or between the endothelial cells. They were quite distinct from larger, numerous rounded blebs two to four endothelial cells in diameter lying beneath the endothelium which have previously been described.
The use of specular microscopy is not confined to the corneal endothelial mosaic, but may be used at any level through the corneal stroma to the posterior endothelial surface. In the stroma the not very dense, irregularly rounded deposits of corneal dystrophies may be differentiated from the dense, geometric shapes of crystalline deposits. At the level of Descemet's membrane the fine parallel lines of tears in Descemet's are distinct from the multiple fine vertical deep stromal lines seen in advanced keratoconus. At the level of the endothelial mosaic the cells may be counted and their morphology examined, while blebs may also be seen in a wide variety of pathological conditions including superficial keratopathies, contact lens wearers, deep keratopathies, anterior uveitis and contusion injury. These blebs vary in size in different conditions and are often transient. They must be distinguished from guttae which are permanent and although an occasional finding in normal corneas are a constant feature of cornea gutatta and Fuchs' dystrophy. On the posterior endothelial surface the relief mode enables the examination of numerous deposits including red blood cells, white blood cells, keratitic precipitates, pigment granules and pseudoexfoliative KP. The morphology of these various findings is discussed.
The ability of the cornea to maintain its transparency after surgery depends primarily upon the integrity of the corneal endothelium and in corneal grafting this is important for both donor and recipient eyes. The corneal endothelium may be significantly affected in various conditions of the anterior segment, especially if these exist over a considerable period of time. These conditions include superficial keratopathy, long-term contact lens wear, cornea guttata and low-grade anterior uveitis, especially chronic cyclitis which may be almost imperceptible clinically. The suitability of such corneas for use as donor material as well as the response of the eyes to anterior segment surgery can be assessed by specular microscopy and this may become even more important in the future as long-term contact lens wearers become more numerous in the community.
Changes on corneal endothelial specular microscopy were compared in 14 patients with cornea guttata, 4 patients with Fuchs' corneal dystrophy and 19 patients with various forms of bullous keratopathy. The patients with cornea guttata showed well marked guttae 1 to 6 endothelial cells in diameter in the endothelial mosaic and in the relief mode while the endothelial mosaic was usually otherwise within normal limits. In 2 patients with Fuchs' dystrophy the endothelium could be examined, showing gross guttae but a few areas of relatively normal endothelial cells. The unaffected eye of 3 other patients showed findings similar to cornea guttata, but with some reduction in endothelial cell count in 2 patients. The patients with bullous keratopathy fell into 2 groups, one with gross reduction in cell count in a markedly abnormal endothelial cell mosaic, the other a mixed group with moderate reduction in cell count and numerous guttae. Some miscellaneous cases included one of aphakic peripheral bullous keratopathy, one associated with cyclitis and aphakia and 2 with idiopathic non-surgical bullous keratopathy. We believe the corneal endothelium is not grossly abnormal away from the guttae in Fuchs' dystrophy, but the gross guttata formation determines the endothelial dysfunction.
Spinocerebellar neurons have been found in previous studies in lamina IX of the lumbosacral spinal cord. This lamina has been characterized as being composed of motor cell groups and the spinocerebellar neurons in the lamina have been found to have certain morphological similarities with the motoneurons. Retrograde double labeling technique, utilizing fluorescent dyes, was used for studying the relations between the spinocerebellar neurons and the motoneurons in lamina IX of the lumbosacral spinal cord in four adult cats. In three of them, Rhodamine labeled latex microspheres were injected bilaterally into the cerebellum and Fast Blue (FB) was injected into hindlimb nerves. In the fourth case, FB was injected into the cerebellum, while the peripheral nerves were injected with propidium iodide. Some overlap was found between labeled spinocerebellar neurons and motoneurons in certain parts of lamina IX, especially in the ventrolateral nucleus in the caudal part of L5 and rostral L6, in the dorsolateral nucleus from the caudal part of L5 to L6 and in the ventromedial nucleus at the S2 level. No double labeled neurons were found, however, in any of these or in other examined areas. This strongly indicates that spinocerebellar neurons in lamina IX are a separate population, different from motoneurons.
Surface marker and gene rearrangement data have supported various hypotheses about the origin of the malignant cell in Hodgkin's disease. Cytogenetic data about this disorder, however, are very scanty. To determine if any chromosomal abnormalities that could add further information to this controversial point are present, we studied tumor samples from 49 patients. Abnormal metaphases were obtained in 18 cases. The most common breakpoints were in 11q23, 14q32, 6q11-21, and 8q22-24. These are common breakpoints in lymphoma and raise the possibility that the malignant cell in Hodgkin's disease may be derived from a lymphocyte. The 11q23 breakpoint is also seen in t(4;11) and t(9;11), which is typical of a type of childhood B-cell acute lymphoblastic leukemia characterized by the presence of aberrant myeloid and monocytic markers. Myeloid and monocytic markers are common in Reed-Sternberg cells.
Use of the relief mode of specular microscopy to differentiate corneal endothelial changes in anterior segment disease from retrocorneal deposits facilitates understanding of the nature of the endothelial changes. The retrocorneal deposits may be pigment granules or inflammatory deposits. The inflammatory deposits may be due to fibrin or WBCs, are more irregular than pigment, and may coalesce to form large, rounded, keratic precipitates. Pigment granules are smaller, denser, usually more regular and, although sometimes confluent, do not form keratic precipitates. Both are distinct from subendothelial blebs, both the smaller blebs up to one cell in diameter and larger blebs of two to three cells in diameter. These blebs are probably due to edema, disappear quickly on resolution of the pathologic process, and are evidence of stress to the endothelium, which shows significant change in morphology and fall in cell numbers when the blebs are of long-standing.
The spinal cord projections of four different groups of hindlimb muscle nerve branches--the medial and lateral gastrocnemius nerves, muscle branches of the deep peroneal nerve, muscle branches of the femoral nerve, and a nerve to the hamstring muscles--were studied with transganglionic transport of horseradish peroxidase (HRP) in the rat. The influence of varying the postoperative survival (3, 6, and 10 days) and of using wheat germ agglutinin-HRP conjugate (WGA-HRP), or HRP with dimethylsulfoxide (DMSO) instead of free HRP was studied for the gastrocnemius nerves. After 3 days' survival following application of HRP to the gastrocnemius nerves, fine granular labeling was found mainly in lamina V in L4-5, and coarse granular labeling was found in Clarke's column as far caudally as L2, and in laminae VI and VII predominantly in Th12-L2. After 6 or 10 days' survival, the fine labeling in lamina V was sparse or absent, whereas the coarse labeling appeared to remain or to be only slightly reduced in Clarke's column and in laminae VI and VII. No labeling suggestive of terminals was observed in laminae I-III from the gastrocnemius nerves. Except for sparse labeling in lamina I in some of the cases and some minor differences rostrocaudally, the spinal distribution of labeling was similar to that from the other nerves investigated. The distribution of labeling obtained after application of WGA-HRP or HRP with DMSO to the gastrocnemius nerves was very similar to that obtained with free HRP after 3 days' survival. The results indicate that the spinal cord projections of hindlimb muscle nerves in the rat distribute mainly in the deep part of the dorsal horn and in the intermediate zone. Furthermore, the lack of labeling suggestive of terminals in laminae I-III from the gastrocnemius nerves suggests, in conflict with earlier findings in the cat, that primary afferent fibers from muscles do not necessarily terminate in these laminae in the rat. The results suggest, furthermore, that fine granular labeling found in lamina V represents fine-calibered afferent fibers. Finally, the similar spinal projection patterns of the different muscle nerves investigated suggest either a less developed or an essentially different somatotopic organization for muscle afferents compared to cutaneous afferents, as revealed in earlier studies.
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We have demonstrated the reversibility of corneal endothelial changes which accompany superficial keratopathy (superficial punctate keratitis, exposure keratopathy, chemical keratopathy and keratoconjunctivitis sicca), stromal keratitis and anterior uveitis (predominantly iridocyclitis). These changes include small subendothelial dark areas equal to or less than one cell in diameter and larger subendothelial dark areas up to two to four cells in diameter. These dark areas are similar but form two groups. The smaller ones may be due to oedema, some developing into larger dark areas, but it is also possible that smaller dark areas represent inflammatory cells or even local destruction of endothelial cells. The larger dark areas elevate the overlying endothelium. Either may be very numerous. They may be present together or separately. They become much less numerous and disappear with resolution or suppression of the acute keratitis or uveitis. The relief mode of corneal specular microscopy was used to distinguish these dark areas from other inflammatory and degenerative changes (such as fine inflammatory deposits, larger keratic precipitates, pigment deposits and guttatae at the level of the corneal endothelium).
Recent work has shown changes in the corneal endothelium accompanying corneal epithelial disease and anterior uveitis. It is important to differentiate these acute changes from other changes such as guttatae or corneal pigment deposition and to assess the magnitude of their effect upon the corneal endothelium. We have used specular microscopy to study changes in the corneal endothelium and Descemet's membrane and to study deposits on the back of the corneal endothelium and correlate them with changes in the endothelium by the use of conventional specular microscopy and by relief images which give a three dimensional view of the area concerned. This has particularly been applied to the conditions of superficial punctate keratopathy, keratoconjunctivitis sicca, corneal abrasions and exposure keratopathy, iritis and cyclitis, pseudoexfoliation of the lens capsule, anterior segment pigment dispersal syndrome, bullous keratopathy as well as corneal guttatae and pigment granules on the posterior cornea. Preendothelial lesions have been distinguished from endothelial and retrocorneal lesions by this technique aiding elucidation of the state of the endothelium. The changes which we noted occurred either at the level of Descemet's membrane (including formation of small rounded dark blebs less than one cell in diameter, larger blebs one to three cells in diameter, and guttatae, usually larger than the foregoing and sometimes very numerous), or at the level of the posterior endothelial surface (including small shiny nodular deposits, often numerous, due to pigment granules, and keratitic precipitates and inflammatory debris, the former usually large and the latter smaller, more irregular and sometimes very numerous). The differentiation and assessment of these various changes are discussed.
We have demonstrated marked changes in the corneal endothelium in some groups of patients with ocular anterior segment disease including chronic cyclitis, both heterochromic and classical, pseudoexfoliation of the lens capsule, and anterior segment pigment dispersal syndrome. The most striking changes occurred in heterochromic cyclitis with reduced endothelial cell counts (p less than 0.01) and altered cellular morphology. In almost all eyes with cyclitis endothelial belbs were seen. In eyes with unilateral pseudoexfoliation of the lens capsule there was a lower endothelial cell count with pleomorphism and polymegathism, the changes being somewhat more marked with raised intraocular pressure (p less than 0.01). In anterior segment pigment dispersal syndrome there was an even smaller reduction in count (p less than 0.05) with mild changes in morphology. Factors producing endothelial cell changes included hypoperfusion of the iris with microneovascularization of the iris stroma, intercellular bleb formation with oedema of the corneal endothelium, and raised intraocular pressure. A normal iris circulation is important to the integrity of the corneal endothelium.
The effects of sciatic nerve resection on lumbar dorsal root ganglion cells and their central branches have been studied in the adult rat. A quantitative analysis of the lumbar dorsal root ganglia indicated a 15-30% cell loss on the operated side. Argyrophilia indicating transganglionic degeneration was observed in Fink-Heimer stained sections from the lumbar spinal cord and the brainstem. The areas of degeneration argyrophilia were mainly located in the medial part of the ipsilateral L2-L6 dorsal horn laminae I-IV, the tract of Lissauer, the dorsal funiculus and the gracile nucleus. A few degenerating fibers could also be observed in the ipsilateral dorsal horn laminae V and VI, and in the ipsilateral ventral horn as well as in the contralateral dorsal horn and the gracile nucleus. The results confirm and extend previous findings at other levels and in other species. This suggests that cell loss and transganglionic degeneration may be general phenomena affecting a substantial proportion of primary sensory neurons following peripheral nerve injury.
The cerebellar projection of neurons in the cervical enlargement was investigated in cats using two neuroanatomical methods, the successive degeneration method (Sherrington and Laslett 1903) and the autoradiographic tracing technique (3H-leucine). With both methods projections were found to the anterior lobe, posterior vermis and paramedian lobule. In the anterior lobe the projection was bilateral mainly to the vermal part of lobules I-V and the adjoining part of lobule VI, although some projection was also observed bilaterally to lobules I-VI lateral to the vermis. In the posterior vermis projection was found bilaterally to lobule VIII and in neighboring parts of lobule VII B. In the paramedian lobule the projection was mainly ipsilateral to the lesions/injections to the pars copularis and the adjoining part of the pars posterior. Only minor differences between the two methods were noted. In conclusion, spinocerebellar neurons project mainly to the vermal area of the anterior lobe (including the most anterior part of lobule VI), to lobules VII B and VIII and to the ipsilateral paramedian lobule.
The interactions between dietary kidney bean (Phaseolus vulgaris) lectins and the epithelial cells of the rat small intestine were investigated by immunogold electron microscopy. The results demonstrated that the lectins bind to the glycocalyx of duodenal and jejunal microvilli and that some of these dietary constituents are endocytosed into lysosomal pathways within both absorptive and secretory gut cells. It is concluded that the lysosomal response serves to limit the absorption of nutritionally significant levels of these dietary toxins.