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At least 469 records · Page 26Linked to original sources
PubMed1983

Clonal analysis of the lymphoid cells mediating skin allograft rejection. Mediation of graft rejection in vivo by cloned Lyt-1+2- proliferative, noncytotoxic long-term cell lines.

Studies were undertaken to elucidate the cellular basis of skin allograft rejection mediated by long-term cultured cell lines and clones. The adoptive transfer, in vivo, of in-vitro-sensitized cells, from B6AF1 anti B10.BR or from C57BL/6 anti DBA/2 cultures, and expanded eight-fold to ten-fold for one week in lectin-free interleukin 2 (LF-IL-2) were able to mediate specific skin allograft rejection. These same cells lost the ability to mediate accelerated skin graft rejection when they were expanded more than 100-fold during three weeks of culture in LF-IL-2 even though these cultures mediated high levels of specific in vitro cytotoxicity for the appropriate allosensitizing cells. When Lyt-2+ cells were depleted using monoclonal antibodies and complement prior to in vitro sensitization and expansion in LF-IL-2, these cells lines retained the ability to mediate skin allograft rejection in vivo when expanded more than 100-fold for three culture generations in vitro. These latter lines were greatly enriched for Lyt-1+2- cells and had little or no cytolytic activity, but they retained specific in vitro proliferative responses to the sensitizing alloantigen. Several Lyt-1-2+ cloned long-term lymphoid cell lines with high levels of specific cytolytic activity against the sensitizing alloantigen were derived and none was capable of mediating the accelerated rejection of skin grafts in vivo. However, cloned lymphoid cell lines that were phenotypically Lyt-1+2- and were capable of proliferating when in contact with specific alloantigen, but were not cytolytic, were capable of mediating the accelerated rejection of skin grafts in vivo both in irradiated mice and in nude mice. These studies demonstrate that skin allograft rejection can be mediated by Lyt-1+2- cell lines with specific in vitro proliferative activity to alloantigen although Lyt-1-2+ cell lines with cytolytic but not proliferative activity to alloantigen in vitro are ineffective in mediating graft rejection in vivo. Specific proliferative activity and no cytolysis appears to be a good in vitro correlate of the in vivo activity of long-term cultured cell lines.

Animals↗
PubMed2003

Clonality analysis of B-cell lymphoproliferative disorders using PCR and melting curve analysis.

Detection of a monoclonal immunoglobulin heavy chain gene (IgH gene) rearrangement is commonly used to support the diagnosis of B-cell non-Hodgkin lymphoma. We investigated the application of melting curve analysis as a substitute for polyacrylamide gel electrophoresis (PAGE) in the detection of monoclonal IgH gene rearrangements after PCR. A total of 140 cases were selected for this study, including 63 B-cell malignancies with a previously documented monoclonal IgH gene rearrangement. These 140 specimens were tested using PCR with melting curve analysis, and the results obtained were compared with PAGE results to calculate the relative sensitivity and specificity of melting curve analysis. Melting curve analysis detected monoclonal rearrangements in 56 of 63 specimens (relative sensitivity 88.9%). No false positives were detected (relative specificity = 100%). False-negative results were obtained only when a weak monoclonal band was present on PAGE. These results show that a positive result on melting curve analysis is specific for a monoclonal IgH gene rearrangement. However, with a sensitivity of only 88.9%, the majority of negative results would require further evaluation of the amplicons using PAGE. The application of melting curve analysis in the detection of monoclonal IgH gene rearrangements in the clinical laboratory setting is discussed.

Adult↗
PubMed1982

Clonal analysis of morphological phenotype in cultured mammary epithelial cells from human milk.

Three main types of colony forming epithelial cell, termed elongated, cuboidal and open, are found in cultures of human milk. Subculture of identified colonies, and cloning from single cells shows that each cell type can maintain its morphological phenotype, but in addition the cuboidal and open cell types can give rise to the elongated type. The results, which suggest a differentiation pathway starting with open cell types, are discussed in relation to differentiation studies on mammary cancer cells.

Breast↗
PubMed1995

Clonal analysis of Haemophilus influenzae type b isolates in the United Kingdom.

Strains of Haemophilus influenzae type b were collected as part of an epidemiological study of bacterial meningitis in the North East Thames Region (NETR) of England. Subclones of H. influenzae were identified by outer-membrane protein typing and multilocus enzyme electrophoresis. These were compared with subclones of H. influenzae type b isolated from elsewhere in the UK. The subclone ET 12.5/OMP 3L was identified in 68% of isolates from cases of meningitis from the NETR. In the isolates from elsewhere in the UK, this subclone was identified in 79% of sterile-site isolates and 91% of isolates from non-sterile sites. This subclone predominated in patients of different ages and from different ethnic groups, which suggests that non-Caucasians are infected with the subclone predominating locally. Since ET 12.5/OMP 3L subclone is the most abundant strain isolated in virtually all other Western European countries, these results provide additional evidence that the genetic diversity in the H. influenzae type b population in Europe is relatively restricted.

Adolescent↗
PubMed1987

MHC class II restricted self-recognition after allostimulation: clonal analysis.

After allostimulation in vitro using a combination of HLA-A, B, C, DR, DQ, D identical but HLA-DP different homozygous typing cells, 34 T cell clones were derived. Thirty-one of them were alloreactive clones, but three clones were found to be autoreactive. One of these autoreactive clones was further expanded. In order to characterize in more detail the determinant restricting the autologous response, a panel of HLA-typed peripheral blood mononuclear cells (PBMC) or Epstein-Barr virus lymphoblastoid cell lines (EVB-LCL) was typed. A good correlation of typing responses with the self haplotype HLA-A1, B8, Cw7, DR3, DRw52, DQw2 was found. Typing responses also segregated together with this haplotype in informative families. Blocking studies using MHC class I and II specific monoclonal antibodies (MoAb) linked the restricting determinant to MHC class II molecules. The clone which was both autoproliferative and autocytotoxic bore the CD3(+), CD4(+), CD8(-), Ia(+) phenotype. Antibiotics or foreign plasma proteins were ruled out as restricted determinants.

Antibodies, Monoclonal↗
PubMed2006

Molecular characterisation and clonal analysis of group A streptococci causing pharyngitis among paediatric patients in Palermo, Italy.

Group A streptococci (n = 123), isolated consecutively from paediatric patients with pharyngitis from Palermo, Italy, were analysed. The emm and sof genes were sequenced, the presence of the speA and speC genes was investigated, and the macrolide resistance phenotypes and genotypes were determined. A limited number of emm/sof genotypes was found, and the most prevalent types were different from those found in a previous study from Rome. Macrolide resistance was found in the most prevalent clones, suggesting that the spread of mobile antibiotic resistance genes among the fittest clones in the community was the main mechanism influencing macrolide resistance rates in different emm types.

Adolescent↗
PubMed1988

Clonal analysis of the response of HL-60 cells to retinoic acid and vitamin D in the presence or absence of leukocyte-conditioned medium.

The capacity of retinoic acid (RA) and vitamin D to induce differentiation of HL-60 cells in an agar gel system that permits a high cloning efficiency was studied in the presence or absence of leukocyte-conditioned medium (LCM). Vitamin D was about 10 times more effective in inducing differentiation than RA. LCM significantly increased the differentiation-inductive capacity of both vitamins, although LCM did not have an effect of its own. During the first days of culture, the number of cells per clone increased with either vitamin or LCM alone as compared to control cultures. This suggests that cellular proliferation may be important in the initial phase of the differentiation induction. No synergy in this respect was found between RA and vitamin D in the presence or absence of LCM. Thus it is doubtful whether RA and vitamin D have a true synergistic effect on individual HL-60 cell differentiation as previously described in liquid cultures. Furthermore, the findings suggest that the process of differentiation induction regarding the growing cells in agar gel involves an all-or-none process. The data may also help elucide the observed relationship between the in vitro production of colony stimulating activity and favorable prognosis of AML.

Cell Differentiation↗
PubMed1974

Clonal analysis of cell division in the Bacillus subtilis div IV-B1 minicell-producing mutant.

Spores of the Bacillus subtilis minicell-producing mutant div IV-B1 were germinated and grown to microcolonies in chambers which facilitate continuous observation of the developing clones with a phase-contrast microscope. Time lapse photographs were taken of 46 clones, covering the period from the beginning of outgrowth until at least two rounds of cell division had been completed. Cell lineages were constructed from contour length measurements of the photographs. These data include cell lengths, division site locations, and cell numbers in clones of various ages. From these data we have determined that the probability of a minicell being produced at any division by the div IV-B1 mutant is 0.31. The location of the abnormal division site which generates the first minicell produced in the outgrowing clone appears to be random with respect to the existing cell poles. In contrast, the location of the second abnormal division site, and hence the second minicell, is not random but rather occurs preferentially in proximity to the first minicell. This clustering of abnormal events suggests that division site location is related to pole age (generations), although other influences on minicell clustering cannot be ruled out at present.

Bacillus subtilis↗
PubMed1992

Clonal analysis of the Actinobacillus pleuropneumoniae population in a geographically restricted area by multilocus enzyme electrophoresis.

The genetic diversity among 250 isolates of Actinobacillus pleuropneumoniae from lungs of pigs with pleuropneumonia and from tonsils of apparently healthy pigs at slaughter was estimated by multilocus enzyme electrophoresis. The Danish strains were derived from both specific-pathogen-free and conventional herds. Sixty-six percent of the isolates belonged to three electrophoretic types (ETs) of a total of 37 ETs detected. While five biotype 2 isolates constituted a separate ET closely related to biotype 1 isolates, the type strain of the species (Shope 4074) belonged to its own ET, with a genetic distance of 0.30 from its nearest neighbor. Isolates of serotypes traditionally considered to have less pathogenic potential (serotypes 6, 10, and 12) from herds with acute outbreaks of pleuropneumonia belonged to the same ETs as isolates from apparently healthy pigs, suggesting that factors such as cross immunity and management may lead to divergent clinical results. Isolates from four herds harboring more than one serotype showed distinct profiles between the serotypes, indicating no or only limited chromosomal recombination among clones. Isolates from tonsils belonged to the same ET as isolates from lungs. The same ET was isolated from widely different parts of the world. Evidence from this study indicates that multilocus enzyme electrophoresis may be a valuable tool for the epidemiological analysis of A. pleuropneumoniae.

Actinobacillus pleuropneumoniae↗
PubMed1992

Clonal analysis of methicillin-resistant Staphylococcus aureus strains from intercontinental sources: association of the mec gene with divergent phylogenetic lineages implies dissemination by horizontal transfer and recombination.

Genetic relationships among 254 isolates of Staphylococcus aureus resistant to methicillin recovered between 1961 and 1992 from nine countries on four continents were determined by analyzing electrophoretically demonstrable allelic variation at 15 chromosomal enzyme loci. Fifteen distinctive electrophoretic types, marking clones, were identified. The mec gene is harbored by many divergent phylogenetic lineages representing a large portion of the breadth of chromosomal diversity in the species, a result that is interpreted as evidence that multiple episodes of horizontal transfer and recombination have contributed to the spread of this resistance determinant in natural populations. Isolates recovered in the United Kingdom, Denmark, Switzerland, Egypt, and Uganda in the 1960s are of a single multilocus enzyme genotype and probably are progeny of an ancestral methicillin-resistant clone. There is geographic variation in the frequency of recovery of the common methicillin-resistant clones, an observation that may in part explain reported regional differences in natural history correlates of resistant organisms.

Enzymes↗
PubMed1993

Clonal analysis of Escherichia coli of serogroups O9, O20, and O101 isolated from Australian pigs with neonatal diarrhea.

The genetic diversity of 87 isolates of Escherichia coli recovered from Australian pigs with neonatal diarrhea was examined by multilocus enzyme electrophoresis. The isolates were of serogroups O9, O20, and O101, and although most isolates lacked K88(F4), K99(F5), 987P(F6), and F41 fimbriae, they were considered to be involved in the etiology of the diarrhea. The isolates were extremely diverse, considering their origin from a single pathological condition in one country. There were estimated to be 18, 16, and 12 clones of the three respective serogroups in the collection, with serogroup diversities of 0.387, 0.448, and 0.275, respectively. Comparison with the results previously obtained for isolates from piglets with postweaning diarrhea suggested that bacteria from piglets with these two conditions did not come from any particular common genetic background. The overall genetic diversity for the combined collection was the same as that reported by others for representative isolates selected from throughout the species (0.47). The current results indicate that if isolates of these O groups are involved in porcine diarrhea, their pathogenicity is directly linked to their O somatic antigen type and is not simply due to the wide distribution of a small number of virulent clones.

Animals↗
PubMed2005

Identification of candidate periodontal pathogens and beneficial species by quantitative 16S clonal analysis.

Most studies of the bacterial etiology of periodontitis have used either culture-based or targeted DNA approaches, and so it is likely that pathogens remain undiscovered. The purpose of this study was to use culture-independent, quantitative analysis of biofilms associated with chronic periodontitis and periodontal health to identify pathogens and beneficial species. Samples from subjects with periodontitis and controls were analyzed using ribosomal 16S cloning and sequencing. Several genera, many of them uncultivated, were associated with periodontitis, the most numerous of which were gram positive, including Peptostreptococcus and Filifactor. The genera Megasphaera and Desulfobulbus were elevated in periodontitis, and the levels of several species or phylotypes of Campylobacter, Selenomonas, Deferribacteres, Dialister, Catonella, Tannerella, Streptococcus, Atopobium, Eubacterium, and Treponema were elevated in disease. Streptococcus and Veillonella spp. were found in high numbers in all samples and accounted for a significantly greater fraction of the microbial community in healthy subjects than in those with periodontitis. The microbial profile of periodontal health also included the less-abundant genera Campylobacter, Abiotrophia, Gemella, Capnocytophaga, and Neisseria. These newly identified candidates outnumbered Porphyromonas gingivalis and other species previously implicated as periodontopathogens, and it is not clear if newly identified and more numerous species may play a more important role in pathogenesis. Finally, more differences were found in the bacterial profile between subjects with periodontitis and healthy subjects than between deep and shallow sites within the same subject. This suggests that chronic periodontitis is the result of a global perturbation of the oral bacterial ecology rather than a disease-site specific microbial shift.

Adult↗