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Negative Staining (negative + staining)
Selected AbstractsSensitive fluorescence detection of polyphosphate in polyacrylamide gels using 4,,6-diamidino-2-phenylindolELECTROPHORESIS, Issue 19 2007Stephanie A. Smith Dr. Abstract PAGE is commonly used to identify and resolve inorganic polyphosphates (polyP). We now report highly sensitive and specific staining methods for polyP in polyacrylamide gels based on the fluorescent dye, 4,,6-diamidino-2-phenylindol (DAPI). DAPI bound to polyP in gels fluoresced yellow while DAPI bound to nucleic acids or glycosaminoglycans fluoresced blue. Inclusion of EDTA prevented staining of glycosaminoglycans by DAPI. We also identified conditions under which DAPI that was bound to polyP (but not nucleic acids or other anionic polymers) rapidly photobleached. This allowed us to develop an even more sensitive and specific negative staining method that distinguishes polyP from nucleic acids and glycosaminoglycans. The lower LOD using DAPI negative staining was 4,pmol (0.3,ng) phosphate per band, compared to conventional toluidine blue staining with a lower LOD of 250,pmol per band. [source] Possible mechanisms for the relative efficacies of ortho -phthalaldehyde and glutaraldehyde against glutaraldehyde-resistant Mycobacterium chelonaeJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2001S.E. Walsh Aims: This investigation compared glutaraldehyde (GTA)-sensitive and -resistant strains of Mycobacterium chelonae and examined the effects of pretreatment of GTA-sensitive and -resistant strains of Myco. chelonae with chemical agents that interfere with cell wall synthesis. Methods and Results: When exposed to 2% (v/v) GTA at 25°C, GTA-resistant strains of Myco. chelonae dried on to glass carriers were not inactivated to any significant extent. By contrast, GTA-sensitive strains of Myco. chelonae and a strain of Myco. terrae suffered a > 6 log reduction in viability in 5 min. However, ortho -phthalaldehyde (OPA; 0·5% w/v) achieved a corresponding inactivation against two GTA-resistant strains within 5,10 and 10,20 min, respectively. Electron microscopy, using a non-aldehyde fixation process and also negative staining, failed to detect any extensive changes in GTA-sensitive and -resistant cultures exposed to GTA or OPA. Thin-layer chromatography was unsuccessful in detecting differences between GTA-resistant and -sensitive strains of Myco. chelonae. However, pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility further to OPA but not to GTA. Conclusions:Ortho -phthalaldehyde is an effective new biocidal agent that, at its in-use concentration, is rapidly bactericidal to non-sporulating bacteria, including GTA-sensitive and -resistant mycobacteria. Significance and Impact of the Study: Pretreatment of GTA-resistant cells with mycobacterial cell wall synthesis inhibitors increased their subsequent susceptibility to OPA but not to GTA. [source] Immunohistochemical analysis of cytokeratin expression in reactive eccrine syringofibroadenoma-like lesion: a comparative study with eccrine syringofibroadenomaJOURNAL OF CUTANEOUS PATHOLOGY, Issue 4 2000Takamitsu Ohnishi In addition to solitary eccrine syringofibroadenoma (ESFA), there is another type of ESFA which is associated with underlying dermatoses (reactive ESFA-like lesion). Five lesions in 4 patients of reactive ESFA-like lesion were analyzed by an immunohistochemical method using 13 kinds of anti-cytokeratin (CK) antibodies. Two cases of solitary ESFA were also studied by the same procedure for comparison. Suprabasal staining pattern of AE1 and MNF116, which stain CKs 6, 16 and 17, markers of hyperproliferative state, was observed diffusely in 5 lesions of reactive ESFA-like lesions except for focal negative staining in one case, and was observed focally in one case of solitary ESFA. Furthermore, differentiation-specific cytokeratin expression was reduced in 3 of 5 lesions of reactive ESFA-like lesions. Both ESFA and reactive ESFA showed basically similar immunoreactivity suggesting differentiation toward the dermal duct. The above slight difference in immunoreactivity between both lesions may be explained due to inflammatory infiltrates associated with underlying dermatoses. [source] Extra small virus-like particles (XSV) and nodavirus associated with whitish muscle disease in the giant freshwater prawn, Macrobrachium rosenbergiiJOURNAL OF FISH DISEASES, Issue 9 2003D Qian Abstract A disease of Macrobrachium rosenbergii, the giant freshwater prawn, farmed in China was recently recorded in Zhejiang, Jiangsu, Shanghai, Guangxi and Guangdong provinces. The clinical sign of the disease, which develops in post-larvae (PL), is a whitish appearance of the muscles, particularly noticeable in the abdomen. Mortalities may reach 100% in some hatcheries. Investigations by transmission electron microscopy after negative staining of diseased PL homogenates showed the presence of two types of viral particles: one, unenveloped, icosahedral in shape, 26,27 nm in diameter, the second, much smaller, about 14,16 nm in diameter, designated extra small virus particle (XSV). The large virus has a genome with two pieces of ssRNA (RNA-1 and RNA-2), of 3 and 1.2 kb, respectively. Hybridization tests confirmed that this large virus is closely related to M. rosenbergii nodavirus (MrNV) which was isolated from diseased prawns in a hatchery in the French West Indies. Its very small size and hypothesized biochemical and biological characteristics suggest XSV is a new type of crustacean virus. As XSV has always been found associated with the larger virus (nodavirus) and is located in muscle and connective cells of diseased animals, it could be an autonomous virus, a helper-type virus or a satellite-like virus. [source] Beta-helix model for the filamentous haemagglutinin adhesin of Bordetella pertussis and related bacterial secretory proteinsMOLECULAR MICROBIOLOGY, Issue 2 2001Andrey V. Kajava Bordetella pertussis establishes infection by attaching to epithelial cells of the respiratory tract. One of its adhesins is filamentous haemagglutinin (FHA), a 500-Å-long secreted protein that is rich in ,-structure and contains two regions, R1 and R2, of tandem 19-residue repeats. Two models have been proposed in which the central shaft is (i) a hairpin made up of a pairing of two long antiparallel ,-sheets; or (ii) a ,-helix in which the polypeptide chain is coiled to form three long parallel ,-sheets. We have analysed a truncated variant of FHA by electron microscopy (negative staining, shadowing and scanning transmission electron microscopy of unstained specimens): these observations support the latter model. Further support comes from detailed sequence analysis and molecular modelling studies. We applied a profile search method to the sequences adjacent to and between R1 and R2 and found additional ,covert' copies of the same motifs that may be recognized in overt form in the R1 and R2 sequence repeats. Their total number is sufficient to support the tenet of the ,-helix model that the shaft domain , a 350 Å rod , should consist of a continuous run of these motifs, apart from loop inserts. The N-terminus, which does not contain such repeats, was found to be weakly homologous to cyclodextrin transferase, a protein of known immunoglobulin-like structure. Drawing on crystal structures of known ,-helical proteins, we developed structural models of the coil motifs putatively formed by the R1 and R2 repeats. Finally, we applied the same profile search method to the sequence database and found several other proteins , all large secreted proteins of bacterial provenance , that have similar repeats and probably also similar structures. [source] Histochemical Analysis of Glycoconjugates in the Skin of a Catfish (Arius Tenuispinis, Day)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010A. Al-Banaw Summary A histochemical study using conventional carbohydrate histochemistry (periodic-acid staining including diastase controls, alcian blue staining at pH 1 and 2.5) as well as using a battery of 14 fluorescein isothiocyanate (FITC)-labelled lectins to identify glycoconjugates present in 10 different areas of the skin of a catfish (Arius tenuispinis) was carried out. The lectins used were: mannose-binding lectins (Con A, LCA and PSA), galactose-binding lectins (PNA, RCA), N -acetylgalactosamine-binding lectins (DBA, SBA, SJA and GSL I), N -acetylglucosamine-binding lectins (WGA and WGAs), fucose-binding lectins (UEA) and lectins which bind to complex carbohydrate configurations (PHA E, PHA L). Conventional glycoconjugate staining (PAS staining, alcian blue at pH 1 and 2.5) showed that the mucous goblet cells contain a considerable amount of glycoconjugates in all locations of the skin, whereas the other unicellular gland type, the club cells, lacked these glycoconjugates. The glycoproteins found in goblet cells are neutral and therefore stain magenta when subjected to PAS staining. Alcian blue staining indicating acid glycoproteins was distinctly positive at pH 1, but gave only a comparable staining at pH 2.5. The mucus of the goblet cells therefore also contains acid glycoproteins rich in sulphate groups. Using FITC-labelled lectins, the carbohydrate composition of the glycoproteins of goblet cells could be more fully characterized. A distinct staining of the mucus of goblet cells was found with the mannose-binding lectins LCA and PSA; the galactosamine-binding lectins DBA, SBA and GLS I; the glucosamine-binding lectin WGA; and PHA E which stains glycoproteins with complex carbohydrate configurations. No reaction occurred with the fucose-binding lectin UEA and the sialic acid-specific lectin SNA. In addition, the galactose-binding lectins PNA and RCA showed only a weak or completely negative staining of the mucus in the goblet cells. The specificity of the lectin staining could be proved by inhibiting binding of the lectins by competitive inhibition with the corresponding sugars. From these data, we can conclude that the mucus produced by the epidermal goblet cells of A. tenuispinis is rich in mannose, N -acetylgalactosamine and N -acetylglucosamine residues. [source] Visualization of Surface-specific Antigens in Various Strains of Enterotoxigenic E. coliANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005S. Lüdi Proteinaceous surface antigens of enterotoxigenic E. coli (ETEC) appear as pili, and are important virulence factors as they allow bacteria to attach to the small intestinal mucosa. Surface antigens are classified as colonization factor antigens (CFA) and coli surface antigens (CS). Known groups include CFA/I, CFA/II (consisting of CS1, CS2 and CS3), CA/III and CFA/IV (consisting of CS4, CS5 and CS6). The goal of the present study was to examine the morphology of pili by transmission electron microscopy (TEM) and to localize specific surface antigens by immunolabelling. Using different strains of E. coli grown under various culture conditions, pili were visualized by negative staining and corresponding surface antigens were demonstrated by immunogold-labelling using both polyclonal and monoclonal antibodies. Expression of pili was dependent on culture conditions and sample handling. In contrast to CFA/I and CS3, CS6 pili were not detectable after negative staining. Selected antibodies, however, allowed surface antigens to be demonstrated unequivocally. These results will be of value in investigating the expression of colonizing factors in genetically modified bacterial strains. [source] Macromolecular crystal data phased by negative-stained electron-microscopy reconstructionsACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2010Stefano Trapani The combination of transmission electron microscopy with X-ray diffraction data is usually limited to relatively large particles. Here, the approach is continued one step further by utilizing negative staining, a technique that is of wider applicability than cryo-electron microscopy, to produce models of medium-size proteins suitable for molecular replacement. The technique was used to solve the crystal structure of the dodecameric type II dehydroquinase enzyme from Candida albicans (,190,kDa) and that of the orthologous Streptomyces coelicolor protein. [source] Prognostic significance of erythropoietin expression in human renal cell carcinomaBJU INTERNATIONAL, Issue 2 2007Agniezka Michael OBJECTIVES To investigate, in a retrospective study, the expression of erythropoietin (Epo) in human renal cell carcinoma (RCC) and its correlation with overall survival, as Epo (an haematopoietic cytokine that regulates the production of red blood cells), with its receptor, was recently localized in non-haematopoietic tissues, e.g. liver, uterus, central nervous system, vascular endothelial cells and solid tumours. PATIENTS AND METHODS We used data from 113 patients who had radical nephrectomy for RCC between 1990 and 2000, taking sections from formalin-fixed and paraffin wax-embedded tissue blocks. The association between Epo staining and the patients' characteristics was assessed by either chi-squared tests (for categorical variables) or two-sample independent t -tests (for continuous variables). RESULTS Tissue from 37 patients (33%) was positive for cytoplasmic Epo expression; 76 (67%) samples were negative. Univariate hazard ratio analysis confirmed that those with positive Epo staining were more than twice as likely to die as those with negative staining (hazard ratio 2.34, 95% confidence interval 1.27,4.3). CONCLUSION This study shows that the expression of Epo in RCC is adversely associated with overall survival. This is the first report of such an association, and might be explained by the loss of Von Hippel-Lindau protein function in clear cell RCC. The expression of Epo might have potential use in clinical trials when stratifying high-risk patients for adjuvant therapy after nephrectomy. [source] ,-catenin expression pattern and DNA image-analysis cytometry have no additional value over primary histology in clinical stage I nonseminomatous testicular cancerBJU INTERNATIONAL, Issue 3 2002J.R. Spermon Objective To determine whether the ,-catenin expression pattern and DNA content have additional value over primary tumour histology, including information on vascular invasion and tunica albuginea invasion, in detecting occult metastasis in patients with clinical stage I nonseminomatous germ cell tumours of the testis (NSGCT). Patients and methods Fifty consecutive patients with clinical stage I NSGCT underwent retroperitoneal lymphadenectomy (RPLND) between 1986 and 1992. The orchidectomy specimens were histopathologically reviewed and immunohistochemically stained with mouse monoclonal anti-,-catenin antibody. The presence of an aberrant or negative staining in >10% of the malignant cells was defined as abnormal; in all other cases tumours were classified as normal. Furthermore, intact nuclei were isolated from 50 µm thick paraffin sections of the primary tumour, Feulgen stained, and analysed with an image-analysis system. Results Of the 50 patients, 14 had positive retroperitoneal nodes (stage IIa, 28%), one pathologically staged I patient developed a lung metastasis (stage IV) within 3 months of RPLND. Univariate analysis showed that the presence of embryonal cell carcinoma, vascular invasion and tunica albuginea invasion were predictive for occult metastases. In multivariate logistic regression analysis only vascular and tunica albuginea invasion were significant. All 11 patients with no embryonal cell carcinoma in the primary tumour were classified as having pathological stage I disease. Also, the tumours which were DNA-diploid (three) or DNA-polyploid (two) were pathologically stage I. In screening for occult metastases the DNA content and the ,-catenin expression pattern had no additional value. Conclusion Vascular and tunica albuginea invasion have prognostic value in identifying patients with clinical stage I NSGCT at high risk for occult retroperitoneal disease. In contrast, the absence of embryonal cell carcinoma could predict all patients at low risk for metastasis. The DNA-ploidy also identified patients at low risk. Other DNA-analyses and the ,-catenin expression pattern provided no additional information. Further studies are recommended to identify patients who are at low or high risk for metastasis. [source] Hypermethylation in promoter region of E-cadherin gene is associated with tumor dedifferention and myometrial invasion in endometrial carcinomaCANCER, Issue 4 2003Ph.D., Tsuyoshi Saito M.D. Abstract BACKGROUND Loss of E-cadherin expression is associated with aberrant 5, CpG island methylation in various tumors. METHODS The authors analyzed the methylation status and immunohistochemical expression of E-cadherin in 142 endometrial tissues, consisting of 21 normal endometria, 17 endometrial hyperplasias, and 104 endometrial carcinomas. RESULTS All normal endometria and endometrial hyperplasias showed positive staining of E-cadherin, and methylation of the E-cadherin gene was not detected in any samples. In endometrial carcinoma, the positive ratio of methylation was higher and was associated with tumor dedifferention and myometrial invasion. In G1 endometrial adenocarcinomas, 66.7% showed positive staining and 33.3% showed heterogeneous staining. Methylation of the E-cadherin gene was detected in 15.6%. In G2 tumors, 19.0% showed positive staining, 69.0% showed heterogeneous staining and 11.9% showed negative staining. Methylation of the E-cadherin gene was found in 50.0%. In G3 tumors, 9.1% showed positive staining, 54.5% showed heterogeneous staining and 36.3% showed negative staining. Methylation of the E-cadherin gene was found in 81.8% of the tumors. Of the samples with no-myometrial invasion, 23.1% had methylation. In those with invasion in less than half of the myometrium, 28.6% did and in those with invasion of half or more of the myometrium, 55.6% had methylation. Of samples that did not have lymph node metastasis, 33.7% had methylation, whereas of samples that had lymph node metastasis, 60.0% had methylation. CONCLUSIONS This is the first report to analyze methylation of the E-cadherin gene promoter of endometrial carcinoma and the evidence suggests that methylation of the E-cadherin gene occurs in association with the acquisition of invasive capacity. Cancer 2003;97:1002,9. © 2003 American Cancer Society. DOI 10.1002/cncr.11157 [source] | |||||||||||||