Search PubMed⌕ Search

Biomedical subjects

M Kiefer

Publications and source records attributed to M Kiefer.

63 records · Page 4Linked to original sources
PubMed1986

Rearrangements of T cell receptor loci can be found only rarely in B lymphoid cells.

We have studied the rearrangement status of the T cell receptor genes in 64 B lymphoid cell lines, and we found that, unlike the immunoglobulin heavy chain genes in T lymphocytes, T cell receptor beta and related gamma chain genes are almost always in germ-line configuration in B lymphoid cells. The only exception was a myeloma MOPC511 (IgA, chi) which contained all T cell receptor genes, beta 1, beta 2, gamma 1, gamma 2, gamma 3 and alpha, in rearranged configuration in both homologous chromosomes. This exception supports the concept that all immunoglobulin and T cell receptor genes exploit the same recombinase to build their complete variable regions. Obviously, in MOPC511 cells the regulation, which confers the tissue specificity i.e. T vs. B lymphocytes, has failed.

B-Lymphocytes↗
PubMed1986

The context of T-cell receptor gamma chain genes among wild mouse species.

We have examined the context of mouse T-cell receptor gamma (Tcr gamma) chain variable (V gamma) and constant (C gamma) genes among a panel of geographically isolated species of mice. Our Southern hybridization survey with C gamma reveals that essentially three C gamma genes are found among mouse species extending phylogenetically from inbred mice through the feral species Mus pahari. However, a V gamma DNA probe detects three to nine V gamma restriction fragment bands among the same group of mice. These results suggest that certain feral mice such as M. pahari, M. platythrix, and M. shortridgei have amplified numbers of V gamma genes. Studies of individual mice from these particular species indicate the highly amplified V gamma content is not the result of a catastrophic gene duplication or deletion event. We conclude that certain species of mice maintain increased content of V gamma presumably for increased diversity in a T-cell response.

Animals↗
PubMed1985

The lymphoproliferating cells of MRL-lpr/lpr mice are a polyclonal population that bear the T lymphocyte receptor for antigen.

Mice bearing the recessive gene lpr develop an age-dependent, massive lymphoproliferation, primarily in the lymph nodes (LN), with associated autoimmunity. LN cells from these mice express T cell receptor protein on the cell surface at 50-70% of normal levels. Normal levels of T cell receptor alpha, beta and gamma mRNA were found in these cells as compared to normal LN cells. Southern blot analysis of MRL-lpr/lpr LN DNA showed rearrangements in 80-90% of the chromosomes at the beta gene loci. The pattern of rearrangement indicated that a polyclonal rather than monoclonal expansion of T cells occurred. These data support a lymphokine-induction model of lymphoproliferation in MRL-lpr mice.

Animals↗
PubMed1985

Isolation of mouse N-CAM-related cDNA: detection and cloning using monoclonal antibodies.

Clones coding for the mouse neural cell adhesion molecule (N-CAM) were isolated from a cDNA library prepared in the expression vector lambda gt 11 from mRNA extracted from a mouse neuroblastoma cell line. This library was screened with two anti-N-CAM monoclonal antibodies directed against different sites on the molecule and with rabbit anti-N-CAM serum. Two clones were identified with the first monoclonal antibody, three with the second one, none reacted with both. The relevance of these cDNA clones to N-CAM was confirmed by several observations. First, cDNA sequences detected with one monoclonal antibody cross-hybridized with those identified by the other antibody. Second, the different fusion proteins all bound the rabbit serum in addition to one monoclonal antibody. Finally, the probes hybridized to discrete mRNA species of sufficient lengths to code for the very large N-CAM polypeptides in RNA preparations from N-CAM-expressing, but not from N-CAM-negative cells. An additional mRNA species not seen in embryonic brain was expressed in adult mouse brain. Genomic blot experiments indicated that sequences corresponding to one of our probes are present only a few times in the mouse genome.

Animals↗
PubMed1977

Transcriptional termination at the end of the early region of bacteriophages T3 and T7 is not affected by polarity suppressors.

Bacterial mutations of known rho genotype (psu-1 through psu-4) were shown to have no effect on transcriptional termination at the termination site at the end of the early region of T3 and T7 DNAs. Transcriptional termination was assayed in these bacterial mutants by comparing the patterns of late protein production produced by T3 and T7 amber I bacteriophage infection. All the rho (psu) mutants tested showed the same pattern of late protein production as the wild-type strain (rho+ or psu+) after T3 or T7 amber I infection. The presence of the mutant rho allele during bacteriophage infection, therefore, did not allow the host RNA polymerase to read through the terminator located at approximately 20% of the T3 and T7 genomes. These results suggest that rho factor may not be involved in reading of the T3 and T7 20% terminators in vivo.

Coliphages↗
PubMedDate not supplied

Ontogeny of the T-cell antigen receptor within the thymus.

The expression of T-cell antigen receptors during T-cell ontogeny is an important issue that bears directly on such questions as where T-cell tolerance is acquired, at what stage T cells become susceptible to repertoire selection, and why most thymocytes die within the thymus. The thymus rudiment is colonized during days 11 and 12 of gestation, but it is not until day 19 that significant numbers of functional thymocytes are present. Although much is known about the ontogeny of function- and specificity-associated surface molecules such as Ly2 and MT4 (the murine equivalent of human T4) during this period, the ontogeny of the T-cell antigen receptors remains obscure. We have now addressed this question on three levels: DNA rearrangement, messenger RNA transcription and expression of cell-surface receptor-like proteins. Our results suggest that T-cell receptors are first expressed within the thymus around day 17 of gestation, independently of and probably before the expression of Ly2 and MT4. Furthermore, these data suggest that all major adult thymocyte subpopulations, including the small cortical cells, most of which die within the thymus, express receptors.

Animals↗
PubMedDate not supplied

Exposures to lead-based paint dust in an inner-city high school.

In response to concerns about lead-based paint (LBP) in an 85-year old high school, an evaluation was conducted to determine whether a lead exposure hazard existed for adult school staff. Deteriorating LBP was present on walls and ceilings throughout the school. At the time of the evaluation, abatement of LBP had been completed in approximately one-third of the school. One-hundred eighteen wipe samples for lead dust were collected from floors, teachers' desks, and interior window sills. Areas selected for sampling were based on the work location of the 45 participants providing blood for lead analysis. Wipe samples from hands were collected from all participants. The geometric means (GMs) for lead dust loadings on sills in unabated rooms (n = 23) and abated rooms (n = 16) were 342 and 102 micrograms/ft2, respectively. Nine sills in unabated rooms and one sill in an abated room exceeded the Housing and Urban Development (HUD) guidelines (500 micrograms/ft2 lead) for residential housing following abatement activity. GMs for lead loadings on floors in unabated rooms (n = 26) and abated rooms (n = 14) were 136 and 70 micrograms/ft2 lead, respectively. Seventeen floor samples from unabated rooms and 3 samples from abated rooms exceeded HUD guidelines (100 micrograms/ft2 lead). The GM blood lead level (BLL) was 2.2 micrograms/dL (range: 0.6-5.6 micrograms/dL), similar to that of the general U.S. population. Despite peeling LBP and significant lead dust loadings, a hazard from LBP was not found for staff at the school. There were no relationships between surface lead and hand lead, BLL and abatement status of assigned work area, or BLL and hand lead.

Adult↗
PubMedDate not supplied

[Possibilities and limits of automatic detection of pathologic intracranial pressure waves with FFT].

Owing to the existence of "reserve spaces" varying individually in extent and expressed by the term compliance, space-consumption intracranial processes do not raise the intracranial pressure (ICP) primarily. Only when this compliance has been exhausted may ICP rise dramatically and may rapidly reach dangerously high levels. It has been shown in the past that "anticipatory" initiation of ICP-reducing measures--i.e. very early in the development of increasing mean ICP--may greatly benefit patient outcome. To recognize an imminent ICP crisis, the available compliance needs to be known. The classical method for determining this latter is the bolus test, which, however, has the disadvantage of being discontinuous and associated with the risk of infection. Another, less invasive and continuous, option is the recognition of pathological intracranial pressure waves. However, recognition of such patterns requires specialized knowledge, that is not widely available. Since, however, knowledge of the compliance is of general importance for intensive care, the idea of developing a PC-based automated system for the identification of pathological waves was followed up. During the course of our basic research effort, we investigated the suitability of the fast Fourier transformation (FFT) algorithm for this purpose. We were able to show that while the FFT is theoretically useful for the detection of pathological intracranial waves, its shortcomings in terms of its sensitivity to extraneous signals (noise) (of considerable importance for biological data handling) and errors in correctly estimating the amplitudes of pathological waves (of great importance for clinical evaluation) make FFT appear less than optimally suitable for this purpose.

Fourier Analysis↗