Melatonin and Sperm Motility/Melatonin und Spermatozoenmotilität

Several substances can interfere with microtubular function eg. colchicine. Melatonin, a hormone secreted by the pineal gland has similar effects as colchicine on microtubules. In this study melatonin levels were determined in both plasma and seminal plasma of patients with good or impaired motility and forward progression. There was no statistically significant difference between the mean plasma and seminal plasma values of patients with good or impaired motility and forward progression. There was no correlation between seminal plasma melatonin and impaired motility or any other semen parameter. There was also no correlation between plasma and seminal plasma concentrations of melatonin. High seminal plasma melatonin concentrations were not necessarily associated with impaired sperm motility. From these it is concluded that seminal plasma melatonin plays no important role in sperm motility.     

Tau protein induces bundling of microtubules in vitro: comparison of different tau isoforms and a tau protein fragment.

Expression of tau protein in non-neuronal cells can result in a redistribution of the microtubule cytoskeleton into thick bundles of tau-containing microtubules (Lewis et al.: Nature 342:498-505, 1989; Kanai et al.: J Cell Biol 109:1173-1184, 1989). We reconstituted microtubule bundles using purified tubulin and tau in order to study the assembly of these structures. Taxol-stabilized tubulin polymers were incubated with various concentrations of recombinant human tau and examined by electron microscopy. With increasing concentrations of tau 3 (tau isoform containing three microtubule binding domains) or tau 4 (isoform containing four microtubule binding domains) the microtubules changed orientation from a random distribution to loosely and tightly packed parallel arrays and then to thick cables. In contrast, tau 4L, the tau isoform containing four microtubule binding domains plus a 58-amino acid insert near the N-terminus, showed minimal bundling activity. tau 4-induced bundling could be inhibited by the addition of 0.5 M NaCl or 0.4 mM estramustine phosphate, conditions which are known to inhibit tau binding to microtubules. A tau construct that contained only the microtubule binding domains plus 19 amino acids to the C-terminus was fully capable of bundling microtubules. Phosphorylation of tau 3 with cAMP-dependent protein kinase had no effect on its ability to induce microtubule bundling. These results indicate that tau protein is directly capable of bundling microtubules in vitro, and suggests that different tau isoforms differ in their ability to bundle microtubule filaments.     

Extraskeletal Osteosarcoma with Unusual Ultrastructural Features

A case of extraskeletal osteosarcoma was observed in the thigh of a 33-year-old male patient. Ultrastructurally the tumor was characterized by the presence of a particular dense type of cell, the nucleus of which showed a characteristic combination of features: large amounts of condensed mar-ginated chromatin, prominent perichromatin granules, vermicellar bodies, and undulating microtubules. The tumor also contained intermediate-type cells with a more typical osteoblastic appearance, and more blastic cells. All three cell types contained varying amounts of dilated rough endoplasmic reticulum with prominent inclusions of crystalline material showing a hexagonal or banded pattern, indicating that the cells represent different stages of maturation rather than genuinely different types of cells. Dense cells showing the same characteristic combination of nuclear features have been described once before in a case of parosteal osteosarcoma. Our results indicate that these cells are a particular form of osteogenic cell. The presence of undulating microtubules and vermicellar bodies suggest a possible association with the presence of virus and/or increased levels of interferon.     

The influence of cooling on the oranization of meiotic spindle of the mouse oocyte

The effect of cooling on the organization of the microtubulesystem of the mouse oocyte has been investigated. Cooling to25, 18 or 4°C for varying periods of time resulted in aprogressive disassembly of the spindle and the dispersal ofthe chromosomes. The extent of the changes observed was greaterat lower temperatures and with longer periods of exposure. Transferof oocytes from either 37 or 4 to 24°C resulted in the rapidand transient appearance of polar asters and of multiple cytoplasmicasters associated with the pericentriolar material present atthe spindle poles and in the cytocortex of the oocyte. Thistransient aster formation appeared to be driven by the elevatedlevels of free tubulin released during spindle disassembly.An apparent reversal of many of the changes induced by low temperaturewas observed in many but not all oocytes on their restorationto 37°C for 1 h. These results have implications for ourunderstanding of microtubule organization in the oocyte, andfor the handling of oocytes during IVF and GIFT therapeuticprocedures and during the cryopreservation of oocytes.     

钙调素对微管组装的调节作用

利用我们建成的钙调素表达可调细胞模型－ＲＣ３细胞，对ＣａＭ高表达时微管组装行为进行了研究，当用生理剂量的地塞米松处理ＲＣ３细胞，细胞内ＣａＭ水平提高，而管蛋白浓度没有变化，造成钙调素／管蛋白比值上升，ＭＴ解聚，但同时加入ＣａＭ拮抗剂三氟拉嗪处理时，则可抑制ＭＴ的解聚，Ｃ３Ｈ１０Ｔ１／２转化细胞ＣａＭ含量的增加是引起ＭＴ解聚的主要因素，ＴＦＰ处理可恢复ＭＴ组装。ＲＣ３细胞ＣａＭ高表达导致ＭＴ解聚的实     

Immunofluorescent detection of anti-cytoskeleton antibodies using vinblastine-treated mononuclear cells

A reliable and reproducible immunofluorescence method is described for the detection of anti-cytoskeleton antibodies in human sera, based on the use of vinblastine-treated peripheral blood mononuclear cells as substrate. Three immunofluorescence patterns associated with antibodies to microfilaments, intermediate filaments and microtubules are readily identified.     

Immunotactoid glomerulopathy with fingerprint immune deposits

Summary Immunotactoid glomerulopathy is a distinct clinico-pathological entity which has recently been defined. The term immunotactoid refers to highly organized immune depositions appearing as rod-like microtubular structures in ultrastructural examination. We describe a patient with mixed connective tissue disease who demonstrates characteristic features of immunotactoid glomerulopathy. The diagnosis was made after excluding amyloidosis, cryoglobulinaemia and lupus nephritis. In addition to immunotactoid microtubules, ultrastructural examination also demonstrated presence of fingerprint depositions which were intimately mixed with immunotactoid structures. Fingerprint deposits have been described in lupus nephritis and cryoglobulin-related nephropathy, but rarely in other glomerulonephritis. These unique findings in our patient may suggest a previously unsuspected relationship between the syndrome of immunotactoid glomerulopathy and systemic lupus erythematosus.     

Ewing's Sarcoma with Neuroblastoma-like Features

Four tumors with the clinical and light microscopic features of Ewing's sarcoma contained cells that possessed to varying degrees ultrastructural features suggestive of neuroblastoma. These neoplasms were considered to be Ewing's sarcoma of bone by radiologic examination and on clinical grounds, and light microscopy was consistent with the diagnosis in every case. It is suggested that the ultrastructural morphology of Ewing's sarcoma is broader than had been supposed and that the presence of dendritic processes in a small cell tumor of bone should not exclude the diagnosis of Ewing's sarcoma.     

Endothelial Regulation of Vascular Repair: Role of bFGF in Paracrine Pathways

Vascular repair following injury is mediated by both endothelial and smooth muscle cells often through paracrine pathways. Basic fibroblast growth factor (bFGF) is present at sites of vascular injury. The role of bFGF in regulating reendothelialization through an effect on centrosome redistribution in cell migration is discussed. The role of bFGF in neointimal formation, especially as it relates to smooth muscle cell proliferation, is reviewed. It is concluded that bFGF appears to be an important agent regulating the early responses of the artery wall to injury. Presented in part at the Molecular Endocrine Pathology Symposium at the International Academy of Pathology XXI International Congress, Budapest, Hungary, October 20–25, 1996.     

Ultrastructural neuropathologic effects of Taxol on neurons of the freshwater snailLymnaea stagnalis

Summary Cerebral ganglia of the freshwater snailLymnaea stagnalis were incubatedin vitro in 10 M Taxol for 8 and 24 h. Cremophor EL (0.1%) was used as a diluant. The tissue was processed for electron microscopy. Various ultrastructural parameters were assessed quantitatively. Cremophor EL appeared to seriously affect the cell somata of the multipeptidergic caudodorsal cells. In the Cremophor-controls the mean area of Golgi zones, the percentage dense material (neuropeptides) in these zones, the number of large electron dense granules (these are involved in neuropeptide processing) and the mean nuclear heterochromatin clump size, were significantly smaller than in the Ringer-controls, whereas the number of lipid droplets was higher. All these parameters, except for the lipid droplets, were not different in the Cremophor-controls and the Taxol-treated specimens. After 24 h treatment, but not after 8 h, Cremophor EL furthermore induced an increase in the number of axonal microtubules. It is argued that the results might signify activation of the neurons by Cremophor EL. Taxol induced a significant increase in the number of microtubules in axons and cell somata. Furthermore an increase in the number of Golgi zones was observed, suggesting activated neuropeptide synthesis. In all groups immunostaining with antibodies to neuropeptides produced by the caudodorsal cells was normal. Release of neuropeptide (exocytosis) from axon endings was elevated after Taxol treatment, and exceptionally high in specimens cotreated with Taxol and Org 2766 (incubation time 22 h). The effect of Org 2766 and Taxol on the number of microtubules was cumulative. It is argued that transport of neuropeptide granules from the cell somata to the axon terminals was not affected by Taxol. It is concluded that Taxol neurotoxicity is probably not due to impeded microtubular axonal transport.