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At least 811 records · Page 45Linked to original sources
PubMed2000

Fine lattice lines on the corneal surface after laser in situ keratomileusis (LASIK).

PURPOSE: To present an example of a pattern of lines resembling fine lattice on the corneal surface subsequent to laser in situ keratomileusis (LASIK). This subtle phenomenon may be relatively common and may affect visual outcome. METHOD: Case report. RESULTS: A 41-year-old year old man with high myopia and best-corrected visual acuity of 20/20 +2 in each eye underwent laser in situ keratomileusis (LASIK). No operative or postoperative complications occurred. No striae were evident on slit-lamp examination with direct illumination and retroillumination at the time of surgery or in the postoperative period. Postoperative uncorrected visual acuity was 20/25 with a best-corrected spectacle correction of 20/25 in both eyes. Fine lines in a lattice pattern were seen only with fluorescein dye in the precorneal tear film as areas of "negative stain" within the LASIK flap. With tear film supplementation, the lines were less evident and visual acuity improved. One year postoperatively, his uncorrected visual acuity was 20/25 in both eyes. The best-corrected spectacle visual acuity was RE: 20/20 -2, LE: 20/25. The fine lines were still present within the flap. A soft contact lens improved visual acuity to 20/20 in both eyes. Although all four puncta were occluded, he had no epiphora. CONCLUSION: Fine lines in a lattice pattern that may represent folds in the epithelium or Bowman layer may be present within the flap after LASIK and may adversely affect visual acuity. They may be visible as areas of negative stain with fluorescein dye in the precorneal tear film in the absence of any striae visible in the flap. These superficial lines have been seen more in patients with high degrees of correction and in patients with dry eye. If visual acuity is affected, it may be improved with punctal occlusion, tear supplements, or a contact lens.

Adult↗
PubMed2002

Isolation and characterization of gap junctions from tissue culture cells.

The purification of membrane proteins in a form and amount suitable for structural or biochemical studies still remains a great challenge. Gap junctions have long been studied using electron microscopy and X-ray diffraction. However, only a limited number of proteins in the connexin family have been amenable to protein or membrane purification techniques. Molecular biology techniques for expressing large gap junctions in tissue culture cells combined with improvements in electron crystallography have shown great promise for determining the channel structure to better than 10 A resolution. Here, we have isolated two-dimensional (2D) gap junction crystals from HeLa Cx26 transfectants. This isoform has never been isolated in large fractions from tissues. We characterize these preparations by SDS-PAGE, Western blotting, negative stain electron microscopy and atomic force microscopy. In our preparations, the Cx26 is easily detected in the Western blots and we have increased expression levels so that connexin bands are visible on SDS-PAGE gels. Preliminary assessment of the samples by electron cryo-microscopy shows that these 2D crystals diffract to at least 22 A. Atomic force microscopy of these Cx26 gap junctions show exquisite surface modulation at the extracellular surface in force dissected gap junctions. We also applied our protocol to cell lines such as NRK cells that express endogenous Cx43 and NRK and HeLa cell lines transfected with exogenous connexins. While the gap junction membrane channels are recognizable in negatively stained electron micrographs, these lattices are disordered and the gap junction plaques are smaller. SDS-PAGE and Western blotting revealed expression of connexins, but at a lower level than with our HeLa Cx26 transfectants. Therefore, the purity and morphology of the gap junction plaques depends the size and abundance of the gap junctions in the cell line itself.

Animals↗
PubMed1969

Electron microscopic study of membranes and walls of bacteria and changes occurring during growth initiation.

Thin sections of stationary-phase Streptococcus lactis cells showed that the wall and membrane are 20 and 7 nm thick, respectively. Whole cells were examined by negative staining with ammonium molybdate and by shadowing. On air-drying of whole cells, the membrane pulled away from the wall revealing adhesions between these organelles. Adhesions could not be seen after subculture of the stationary-phase cells into complex media or into solutions containing glucose, KCl, and CaCl(2) in tris(hydroxymethyl)aminomethane buffer. The adhesions were also observed in stationary-phase cells of other gram-positive bacteria. Fractured freeze-etched cells of S. lactis had a smooth outside surface, but the inside of the wall (or outside of the membrane) had a regular structure, repeating at 10 nm, which could correspond to the adhesions observed in the negatively stained air-dried cells. Freeze-etching also revealed holes in the outside wall which had the shape of inverted truncated cones. The outside diameter of the cone was 60 nm, and the diameter on the inside surface of the wall was 20 nm. The membrane had upstanding plugs, 20 nm in diameter, which could fill the holes in the wall.

Bacillus cereus↗
PubMed1975

Structure and composition of the adenovirus type 2 core.

The structure and composition of the core of adenovirus type 2 were analyzed by electron microscopy and biochemical techniques after differential degradation of the virion by heat, by pyridine, or by sarcosyl treatment. In negatively stained preparations purified sarcosyl cores reveal spherical subunits of 21.6-nm diameter in the electron microscope. It is suggested that these subunits are organized as an icosahedron which has its axes of symmetry coincident with those of the viral capsid. The subunits are connected by the viral DNA molecule. The sarcosyl cores contain the viral DNA and predominantly the arginine/alanine-rich core polypeptide VII. When sarcosyl cores are spread on a protein film, tightly coiled particles are observed which gradually unfold giving rise to a rosette-like pattern due to the uncoiling DNA molecule. Completely unfolded DNA molecules are circular. Pyridine cores consist of the viral DNA and polypeptides V and VII. In negatively stained preparations of pyridine cores the subunit arrangement apparent in the sarcosyl cores is masked by an additional shell which is probably formed by polypeptide V. In freeze-cleaved preparations of the adenovirion two fracture planes can be recognized. One fracture plane probably passes between the outer capsid of the virion and polypeptide V exposing a subviral particle which corresponds to the pyridine core. The second fracture plane observed could be located between polypeptide V and the polypeptide VII-DNA complex, thus uncovering a subviral structure which corresponds to the sarcosyl core. In the sarcosyl core polypeptide VII is tightly bound to the viral DNA which is susceptible to digestion with DNase. The restriction endonuclease EcoRI cleaves the viral DNA in the sarcosyl cores into the six specific fragments. These fragments can be resolved on polyacrylamide-agarose gels provided the sarcosyl cores are treated with pronase after incubation with the restriction endonuclease. When pronase digestion is omitted, a complex of the terminal EcoRI fragments adenovirus DNA and protein can be isolated. From this complex the terminal DNA fragments can be liberated after pronase treatment. The complex described is presumably responsible for the circularization of the viral DNA inside the virion. The nature of the protein(s) involved in circle formation has not yet been elucidated.

Adenoviridae↗
PubMed1986

An analysis of the sensitivity and specificity of the cytokeratin marker CAM 5.2 for epithelial tumours. Results of a study of 203 sarcomas, 50 carcinomas and 28 malignant melanomas.

Two hundred and three sarcomas, 40 carcinomas, 10 carcinomas with spindle cell features, 27 malignant melanomas and one spindle cell melanoma were examined using CAM 5.2, a monoclonal antibody to cytokeratin. This antibody which was prepared against colorectal carcinoma cells and which identifies low molecular weight intermediate filament cytokeratin proteins is suitable for use in formalin fixed, paraffin embedded material. Seventeen of the 203 sarcomas showed positive staining. These included 15/21 synovial sarcomas, 1/5 epithelioid sarcomas and 1/18 malignant neural tumours. Five carcinosarcomas showed positive staining of their epithelial components but negative staining of their spindle cell components; three out of four pure spindle cell carcinomas stained positively; a metastasis from a spindle cell renal carcinoma was negative. A spindle cell thymoma also stained positively. Thirty-seven of the 40 carcinomas stained positively; the three negative carcinomas were a squamous cell carcinoma, a renal cell carcinoma and an oat cell carcinoma. All malignant melanomas were negative. These results are compared with those of other workers and the sensitivity and specificity of CAM 5.2 as an epithelial marker is assessed.

Antibodies, Monoclonal↗
PubMed1993

Ethanol-elicited structural and biochemical alterations in mitochondrial ATPase in cultured myocardial cells.

The effects of ethanol (12.5-500 mM for up to 24 h) on mitochondrial structure including that of ATPase particles in cultured ventricular myocardial cells were studied using negative-stain electron microscopy. The activity of mitochondrial ATPase after ethanol treatment was also examined cytochemically and biochemically. At 5 min after the addition of all the concentrations of ethanol examined, some mitochondrial cristae were expanded and the arrangement of mitochondrial ATPase particles on these cristae was disordered. At and after 30 min the cristae decreased in number and some were expanded, vesiculated or fragmented. ATPase particles also decreased in number, particularly after the application of ethanol in concentrations of more than 50 mM. All the mitochondria had broadened and translucent cristae, and lacked ATPase particles with 200 and 500 mM ethanol at 24 h, although with 12.5 and 50 mM ethanol some mitochondria had similar negatively stained images but others had ATPase particles on broadened cristae. The enzymatic activity of the mitochondrial ATPase was unchanged with 200 and 500 mM ethanol at 24 h, compared with controls. The cytochemical technique also detected enzyme activity with all the concentrations of ethanol examined at 24 h. The discrepancy between the structural and biochemical alterations in mitochondrial ATPase induced by ethanol is discussed.

Adenosine Triphosphatases↗
PubMed1992

A method for determining the periodicity of a troponin component in isolated insect flight muscle thin filaments by gold/Fab labelling.

Insect flight muscle has a large component (Tn-H) in the tropomyosin-troponin complex that is not present in vertebrate striated muscle thin filaments. Tn-H is shown by gold/Fab labelling to be present at regular intervals in insect flight muscle thin filaments. The Fab fragment of a monoclonal antibody to Tn-H was conjugated directly with colloidal gold and this probe used to label isolated thin filaments from the flight muscle of Lethocerus indicus (water bug). The distribution of gold particles seen in electron microscope images of negatively stained thin filaments was analysed to show that the probe bound to sites having a periodicity of approximately 40 nm, which is the expected value for the tropomyosin-troponin repeat. Conjugates of Fab with colloidal gold particles of 3 nm diameter labelled almost all sites. Conjugates with gold particles of 5 nm and 10 nm diameter labelled less efficiently (70% and 30%, respectively) but analysis of the distribution of inter-particle intervals among a number of filaments again gave the same fundamental spacing of 40 nm. The error in the measurements (standard deviation approximately +/- 4.2 for 5 nm gold/Fab) is less than earlier estimates for the size of the gold/Fab complex. Measurements on gold/Fab in negative stain suggest that the bound Fab contributes a shell about 2 nm in thickness around the gold particle. The radius of the probe (about 4.5 nm for 5 nm gold/Fab) would then be consistent with the value of error found. The size of the probe suggests that the gold particle binds to the side of the Fab molecule, rather close to the antibody combining site. The potential resolution of the technique may thus be better than originally expected.

Animals↗
PubMed1990

Electron cryo-microscopic analysis of crystalline cytochrome oxidase.

The structure of cytochrome oxidase from beef heart mitochondria has been analysed by cryo-electron microscopy of vesicle crystals of the space group p22(1)2(1), with cell dimensions a = 102 A, b = 123 A, gamma = 90 degrees. Several methods of specimen preparation were applied to the vesicular two-dimensional crystals in the electron microscope, to ensure that the structure was preserved to the maximum resolution. The two most informative density maps were from specimens embedded in ice and from negative staining in a 1:1 mixture of glucose and uranyl acetate. The three-dimensional structure of the ice-embedded molecule shows a single, well resolved, but convoluted density, which represents in size and shape one cytochrome oxidase dimer. At the bottom of the molecule, a substantial part of the protein is embedded in the lipid bilayer of the vesicle. The molecule then extends upwards, out of the bilayer, into the internal space within the vesicle. Here, the structure first passes through a region within the molecule containing a hollow cavity that lies roughly at the centre of mass of the dimer, and then branches into two well-resolved halves at some distance from the membrane. The negatively stained structure, in contrast, shows a stain-excluding region in the centre of the vesicle at the level of the cavity in the ice-embedded structure, but otherwise has a similar overall external shape. In addition, there is a small rotation of the whole molecule by approximately 25 degrees relative to the orientation of ice-embedded specimens. We interpret these differences to mean that the central cavity seen in the ice-embedded structure is too small to allow the stain to penetrate during the drying process and that the drying process causes the rotation. The structures described here are consistent with one another and allow an interpretation at higher resolution than from previous work.

Animals↗
PubMed1988

Association of purified thyroid lysosomes to reconstituted microtubules.

We report the characteristics of the interaction between reconstituted microtubules and purified thyroid lysosomes. Microtubules were extracted from pig brain by temperature-dependent assembly-disassembly and labelled with 125I by conjugation with the Bolton-Hunter reagent. Thyroid lysosomes were purified from pig thyroid by isopycnic centrifugation on Percoll gradients. The formation of microtubule-lysosome complexes has been studied by electron microscopy, using negative staining, and by differential centrifugation. The association of lysosomes to microtubules is time- and temperature-dependent (between 25 degrees C and 37 degrees C). The rate of microtubule-lysosome complex formation is related to the concentration of lysosomes. The higher the lysosome concentration is, the higher also is the rate of the interaction. Changes in microtubule concentration merely alter the amount of complex formed; there is a linear relationship between the amount of complexes and the microtubule concentration. However, lysosomes seem to possess a limited number of 'microtubule-binding sites', since a saturation of the complex formation can be obtained at high microtubule concentration. Two main types of complex have been observed by electron microscopy on negatively stained samples; simple complexes composed of a lysosome in close contact with a microtubule and complexes formed by a lysosome surrounded by several microtubules. The formation of microtubule-lysosome complexes was totally inhibited in the presence of 100 microM N-ethylmaleimide; the rate of the interaction was slightly increased in the presence of dithiothreitol (25-100 microM). The interaction we describe here in an acellular system might be relevant to the association of lysosomes to microtubules observed in intact cells (Collot, M., Louvard D. and Singer S.J. (1984) Proc. Natl. Acad. Sci. USA 81, 788-792) and will constitute a useful model to study the regulation mechanisms of microtubule-vesicle interaction.

Animals↗
PubMed1997

Media from rhabdomyosarcoma and neuroblastoma cell cultures stimulate in vitro aggregation and fibrillization of amyloid beta-protein.

In vitro aggregation and fibrillization of synthetic amyloid beta-protein Abeta 1-40 was assessed in the conditioned media from rhabdomyosarcoma (CRL 1598, HTB 82, HTB 153, CCL 136), adenocarcinoma (CCL 218), neuroblastoma (SY5Y), and COS cells cultured in the absence and presence of 10% heat-inactivated fetal bovine serum (FBS). The aggregation and formation of cross beta-pleated sheet structures in Abeta was quantitated by Thioflavin T (ThT) fluorescence spectroscopy, while the morphology of Abeta fibrils was examined in negative staining in the electronmicroscope (EM). In cultures supplemented with 10% FBS, the conditioned media from CRL 1598, HTB 82, CCL 218, and SY5Y cell cultures stimulated Abeta aggregation in a time-dependent manner as compared to that of control (serum-containing medium that had not been exposed to cells). The order of stimulation was SY5Y > CRL 1598 > or = HTB 82 > CCL 218, and the stimulation was higher in 2 week cultures than in 1 week cultures. Similar studies using media from HTB 153, CCL 136 and COS cell cultures showed no effect on Abeta 1-40 aggregation. In serum-free cell cultures, only media from SY5Y and CRL 1598 could promote significant aggregation of Abeta 1-40. Negative staining in EM revealed Abeta fibril formation only with conditioned media from SY5Y and CRL 1598 cultured under serum free conditions; no Abeta fibrils were noticed in media from cell cultures supplemented with 10% FBS. We propose that both the SY5Y neuroblastoma cell line and the CRL 1598 rhabdomyosarcoma cell line may serve as experimental models for in vitro studies of extracellular aggregation and fibrillization of Abeta-protein in cell cultures, while rhabdomyosarcoma HTB 82 and adenocarcinoma CCL 218 may be models for study of Abeta aggregation only.

Adenocarcinoma↗
PubMed1983

Structure of myosin/paramyosin filaments from a molluscan smooth muscle.

Small-angle X-ray diffraction patterns of chemically skinned pedal retractor muscles from Mytilus (PRM) in the relaxed state show a set of diffuse off-meridional reflections that arise from a helical array of myosin crossbridges with 8/3 screw symmetry. Experiments involving extraction of myosin as well as analysis of the rigor pattern have been used to confirm the origin of these reflections. The relatively high myosin/paramyosin molar ratio (1.3 to 1.6) in PRM compared to other molluscan smooth muscles may account for the observation of the relatively stronger diffraction from the myosin array. Thick filaments isolated from PRM and contrasted by negative staining for electron microscopy appear to be very long (up to 17 micron), and to have a rather small diameter (about 40 nm at the center); they taper gradually toward the ends. These filaments show a clear transverse band pattern repeating at 14.4 nm and elongated projections (crossbridges) at the surface except in the central bare zone. Optical diffraction patterns show reflections from crossbridges consistent with the X-ray patterns of the relaxed whole muscle. Filaments unidirectionally shadowed with platinum show diagonal striations running at an angle of about 17 degrees to the filament axis, revealing that the crossbridges are arrayed in a right-handed helix. The paramyosin core is clearly seen upon extraction of myosin. Observations on both negatively stained and sectioned material are consistent with the results of Elliott (1979) and Bennett & Elliott (1981) suggesting a layered structure of the core. Cores stripped of myosin, however, appear to undergo some distortion indicating that the three-dimensional structure is not yet completely solved. The assembly of these thick filaments presents intriguing structural problems since the myosin surface lattice does not appear to have the same symmetry as the underlying paramyosin core.

Animals↗
PubMed1989

Structural changes induced in Ca2+-regulated myosin filaments by Ca2+ and ATP.

We have used electron microscopy and proteolytic susceptibility to study the structural basis of myosin-linked regulation in synthetic filaments of scallop striated muscle myosin. Using papain as a probe of the structure of the head-rod junction, we find that this region of myosin is approximately five times more susceptible to proteolytic attack under activating (ATP/high Ca2+) or rigor (no ATP) conditions than under relaxing conditions (ATP/low Ca2+). A similar result was obtained with native myosin filaments in a crude homogenate of scallop muscle. Proteolytic susceptibility under conditions in which ADP or adenosine 5'-(beta, gamma-imidotriphosphate) (AMPPNP) replaced ATP was similar to that in the absence of nucleotide. Synthetic myosin filaments negatively stained under relaxing conditions showed a compact structure, in which the myosin cross-bridges were close to the filament backbone and well ordered, with a clear 14.5-nm axial repeat. Under activating or rigor conditions, the cross-bridges became clumped and disordered and frequently projected further from the filament backbone, as has been found with native filaments; when ADP or AMPPNP replaced ATP, the cross-bridges were also disordered. We conclude (a) that Ca2+ and ATP affect the affinity of the myosin cross-bridges for the filament backbone or for each other; (b) that the changes observed in the myosin filaments reflect a property of the myosin molecules alone, and are unlikely to be an artifact of negative staining; and (c) that the ordered structure occurs only in the relaxed state, requiring both the presence of hydrolyzed ATP on the myosin heads and the absence of Ca2+.

Actin Cytoskeleton↗
PubMed1993

[Mechanism of pore formation on erythrocyte membrane by streptolysin-O].

The erythrocyte membrane damaged by streptolysin-O (SLO) was observed in negative staining electron microscopy. It was confirmed that rings took arc (c-ring), sigmoidal (s-ring) or circular (o-ring) structures, and had electron-dense centers of a diameter of 24 nm and 4.9 nm width. We found a crown structure on top of the ring in view of side projection. The ring structure was constructed by three layers of the electron lucent top which was the crown, the second dark layer, and the third, base part which embedded in the erythrocyte membrane, and the heights were 3.2, 1.6, 5.0 nm, respectively. When the ghost membrane of erythrocyte was treated with SLO, the double of the inner and outer layers of a ring were observed by the negative-staining images. The figures of rings taken by under focus showed that one ring might be constituted between the 22 and 24 pair of inner and outer molecules. Totally 44 or 48 toxin molecules might be required for one O-ring.

Animals↗
PubMed1989

[Observation of erythrocyte flow in retinal vessels during fluorescein angiography].

Erythrocytes do not take up fluorescein intracellularly during angiography, they are hypofluorescent compared to blood plasma. This negative staining phenomenon has not been observed in the human retina. Scanning Laser Ophthalmoscopy permits imaging of the retina with a higher temporal and a higher spatial resolution than a conventional funduscamera. Thus, the retinal erythrocyte flow can be observed during fluorescein angiography. The red blood cells are seen as multiple black dots in a superficial layer of the intravasal blood column. A pathologically reduced blood flow can be recognized by simple observation. The velocity of the red blood cells is estimated with an erythrocyte velocimeter, that permits an optical comparison between the velocity of black dots and the velocity of the cells in the retinal vessel. The measured values fit well to the data obtained with the laser doppler technique. Therefore, the negative staining phenomenon in association with scanning laser ophthalmoscopy gives us a new tool in retinal microcirculation research.

Erythrocytes↗
PubMed1986

Helical structure of Bordetella pertussis fimbriae.

The helical structures of Bordetella pertussis fimbriae of serotypes 2 and 6 were determined by optical diffraction analysis of electron micrographs of negatively stained paracrystalline bundles of purified fimbriae. The fimbrial structure is based on an axial repeat of 13 nm that contains five repeating units in two complete turns of a single-start helix. This structure was confirmed by direct measurements of mass per unit length for individual fimbriae performed by dark-field scanning transmission electron microscopy of unstained specimens. These data further established that the helically repeating unit is a monomer of fimbrial protein (Mr congruent to 22,000 for type 2 and Mr congruent to 21,500 for type 6). Radial density profiles calculated from the scanning transmission electron micrographs showed that the fimbria has peak density at its center, i.e., no axial channel, consistent with the results of conventional negative-staining electron microscopy. The radial profile gives an outermost diameter of approximately 7.5 nm, although the peripheral density is, on average, diffuse, allowing sufficient intercalation between adjacent fimbriae to give a center-to-center spacing of approximately 5.5 nm in the paracrystals. Despite serological and biochemical differences between type 2 and type 6 fimbriae, the packing arrangements of their fimbrial subunits are identical. From this observation, we infer that the respective subunits may have in common conserved regions whose packing dictates the helical geometry of the fimbria. It is plausible that a similar mechanism may underlie the phenomenon of phase variations in other systems of bacterial fimbriae.

Bordetella pertussis↗
PubMed1987

Ultrastructure and biochemistry of the cell wall of Methanococcus voltae.

The ultrastructure and chemical composition of the cell wall of the marine archaebacterium Methanococcus voltae were studied by negative-staining and freeze-etch electron microscopy and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. M. voltae possesses a single regularly structured (RS) protein layer external to the plasma membrane. Freeze-etch preparations of cells indicated that the protein subunits are hexagonally arranged with a center-to-center spacing of approximately 10 nm. The extracted RS protein had a molecular weight of 76,000. It was present on envelopes prepared by shearing in a French press, osmotic lysis, or sonication, as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. NaCl was not required for attachment of the RS protein to the underlying plasma membrane. The hexagonal array could be demonstrated by platinum shadowing and freeze-etching of envelopes, but negative staining in the abscence of NaCl failed to stabilize the array. The RS protein could be solubilized by urea, guanidine hydrochloride, dithiothreitol, and several detergents, including Nonidet P-40, Triton X-100, and Tween 20. However, the most specific release of the wall protein from envelopes occurred after a heat treatment in HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) buffer at 50 to 60 degrees C.

Bacterial Proteins↗
PubMed1996

[Expression of glutathione S-transferase pi and numerical aberration of chromosome 11 in human ovarian cancer as a prognostic indicator].

In 33 patients with primary ovarian cancer who had not received any chemotherapy before surgery, expression of glutathione S-transferase pi (GST-pi) was studied immunohistochemically in relation to the response to chemotherapy with CDDP, and furthermore it was examined whether numerical aberration of chromosome 11 was available as a prognostic indicator. The obtained results were as follows: 1. Of 33 ovarian cancer tissue samples, 19 (57.6%) showed positive staining and 14 (42.4%) negative staining for GST-pi. 2. The 5 year survival rate of the patients with GST-pi positive tumors was significantly lower than that of those with GST-pi negative tumors (p < 0.01). 3. The frequency of detection of cells showing numerical aberration of chromosome 11 in tissues was significantly higher in ovarian cancers than in benign ovarian tumors and normal ovaries. 4. The 5 year survival rate of the patients with ovarian cancer in which the cells showing numerical aberration of chromosome 11 at 20% or more was significantly lower than that of those in which such cells were under 20% (p < 0.02). These results show that expression of GST-pi and numerical aberration of chromosome 11 in the tissues of human ovarian cancers are useful as prognostic indicators.

Chromosome Aberrations↗
PubMed1983

Ultrastructural morphology of amyloid fibrils from neuritic and amyloid plaques.

The structure of partially purified, CNS amyloid fibrils from three different sources have been compared by negative stain EM. The fibrils isolated from brains with senile dementia of Alzheimer type were 4-8 nm in diameter, narrowing every 30-40 nm and apparently composed of two 2-4 nm filaments. The fibrils from a Gerstmann-Sträussler syndrome brain were 7-9 nm in diameter, narrowing every 70-80 nm and with a suggestion that they are composed of two 3-5 nm filaments. The fibrils isolated from 87V scrapie-affected mouse brains were 4-8 nm in diameter with a twist every 15-25 nm presumably composed of two 2-4 nm filaments. The fibrils from the scrapie brains were usually observed in pairs. The shape of the clusters of the isolated amyloid fibrils observed in each disease was similar in negative stain and thin section EM preparations and was related to the characteristic morphology of the amyloid fibrils in the neuritic and amyloid plaques in situ. The structural differences between the CNS amyloid fibrils from the various diseases studied by us may reflect differences in the polypeptides which comprise the fibril and/or a different pathogenesis in the formation of the amyloid fibrils.

Alzheimer Disease↗