PubMed Health⌕ Search

Biomedical subjects

C Mueller

Publications and source records attributed to C Mueller.

At least 163 records · Page 9Linked to original sources
PubMed1988

A high proportion of T lymphocytes that infiltrate H-2-incompatible heart allografts in vivo express genes encoding cytotoxic cell-specific serine proteases, but do not express the MEL-14-defined lymph node homing receptor.

The role of cytotoxic cells in in vivo immune functions such as allograft rejection is unknown. To begin to assess the function of cytolytic cells in vivo we have begun with cytolytic cell-specific functional molecules: we have isolated and characterized cytolytic cell-specific cDNA clones from cytolytic T cell clones, both encoding distinct serine esterases. The HF gene encodes a trypsin-like enzyme while the C11 gene encodes an enzyme with likely specificity for acidic residues. Here we demonstrate, using in situ hybridization with RNA probe, that both genes are expressed selectively in a subset of T lymphocytes that have infiltrated cardiac allografts. The phenotype of these cells is consistent with the most frequent phenotype of active CTL raised in vitro: they are predominantly CD4-, CD8+, MEL-14- T cell blasts. Thus the expression of these genes, each of which encodes serine esterase found in killer cell granules in vitro, is a valid marker for these cells in vivo as well. The kinetics of their accumulation is consistent with, but not proof of, a putative role in allograft rejection. It is likely that HF and C11 gene expression will be of diagnostic value.

Animals↗
PubMed1988

A T cell- and natural killer cell-specific, trypsin-like serine protease. Implications of a cytolytic cascade.

A new trypsin-like serine protease was cloned from both a murine cytotoxic T lymphocyte and a human PHA-stimulated peripheral blood lymphocyte cDNA library. In both the mouse and human system, this transcript had a T cell- and NK-specific distribution, being detected in cytotoxic T lymphocytes (CTL), some T-helper clones, and NK, but not in a variety of normal tissues. T-cell activation with Con A plus IL-2 induced mouse spleen cells to express this gene with kinetics correlating with the acquisition of cytolytic capacity. Both the mouse and human nucleotide sequences of this gene encoded an amino acid sequence with 25-40% identity to members of the serine protease family. The active-site "charge-relay" residues (His-57, Asp-102, and Ser-195 of the chymotrypsin numbering system) are conserved, as well as the trypsin-specific Asp (position 189 in trypsin). We reviewed the evidence of this serine protease's role in lymphocyte lysis and proposed a "lytic cascade." We discussed the biological and clinical implications of a cascade, proposing these enzymes as markers for cytolytic cells and as targets for rational drug therapy. Genetic and acquired deficits in the lethal hit-delivery system are considered as a basis for approaching some immunodeficiency states, including severe EBV infections, T-gamma leukemias, and T8+ lymphocytosis syndromes.

Amino Acid Sequence↗
PubMed1988

In situ localization of HuHF serine protease mRNA and cytotoxic cell-associated antigens in human dermatoses. A novel method for the detection of cytotoxic cells in human tissues.

Human Hanukah Factor (HuHF) is a trypsinlike serine protease associated with cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Employing a radiolabeled RNA probe for the HuHF gene, cells containing HuHF mRNA in situ were detected in skin lesions from patients with a variety of reactive and neoplastic dermatoses including positive allergic contact dermatitis patch tests, lichen planus, erythrodermic psoriasis, Sezary syndrome, and poikilodermatous mycosis fungoides. The results were correlated with in situ studies of CTL/NK subsets as defined immunohistologically by a panel of monoclonal antibodies applied to sermiserial sections of the same tissue blocks used for the HuHF hybridizations. The results suggest that cytotoxic cells are present in each of these dermatoses, that they may be situated within either the epidermis or the dermis, and that they belong predominantly to the CTL subset because Leu-7+ or CD16+ cells (NK cells) were typically rare or absent. A variable proportion of cells expressed Leu-19 antigen (a marker for non-MHC-restricted cytotoxic cells); however, its rarity in several cases suggests that most of the HuHF+ cells identified in them belonged to the MHC-restricted, Leu-19- CTL subset. It is concluded that the correlation of molecular biologic and immunohistologic data will be a useful method for the further characterization of cytotoxic cell subsets in human dermatoses.

Antigens↗
PubMed1987

Kinetic and molecular properties of the dihydrofolate reductase from pyrimethamine-sensitive and pyrimethamine-resistant clones of the human malaria parasite Plasmodium falciparum.

Dihydrofolate reductase (DHFR) (5,6,7,8-tetrahydrofolate: NADPH+-oxidoreductase; EC 1.5.1.3) was partially purified by affinity chromatography from three clones of the human malaria parasite Plasmodium falciparum. The three clones were representative of pyrimethamine-sensitive (clone 3D7) and pyrimethamine-resistant (clone HB3 and clone 7G8) parasites with ID50 values of 0.53 nM (3D7), 210 nM (HB3), and 540 nM (7G8), when tested in vitro against the drug. The specific activities of the partially purified DHFR differed by less than a factor of 2 between the sensitive clone 3D7 (442 +/- 39 nmol min-1 mg-1 protein) and the resistant clones HB3 (634 +/- 25 nmol min-1 mg-1 protein) and 7G8 (565 +/- 85 nmol min-1 mg-1 protein). The number of catalytic sites in partially purified DHFR from the three clones was similar and ranged from 151 to 194 pmol mg-1 protein. The Km value for NADPH was similar in all three clones (4.5-11.6 microM). The Km value for dihydrofolate was altered 13-fold comparing the sensitive clone 3D7 (3.2 +/- 0.6 microM) with the resistant clone HB3 (42.6 +/- 1.6 microM), with the Km for the resistant clone 7G8 falling in between (11.9 +/- 1.2 microM). The inhibition constants for pyrimethamine increased from 0.19 +/- 0.08 nM (3D7) to 2.0 +/- 0.3 nM (HB3) to 8.9 +/- 0.8 nM (7G8). The inhibition by pyrimethamine of the sensitive clone 3D7 was noncompetitive and competitive for the two other clones. The titration of partially purified DHFR with pyrimethamine revealed a 500-fold increase in the concentration of the drug needed to inhibit the DHFR activity by 50%, when the sensitive clone 3D7 (0.18 +/- 0.02 nM) was compared to the resistant clone 7G8 (95 +/- 16 nM). From the comparison of the specific activities and the catalytic center activities with the Km values for the substrate and the inhibition constants for pyrimethamine, both of which are altered in the resistant clones, we conclude that the molecular mechanism for pyrimethamine resistance in the three clones studied is not based on an overproduction of the DHFR but is due to a decreased affinity to antifolates by a structurally altered enzyme.

Chromatography, Affinity↗
PubMed1987

Parathymic lymph node: oriented proliferative response of the murine thymic cortex to intraperitoneal stimulation.

This study was designed to answer the question if a primary immune response elicited in parathymic lymph nodes would influence the proliferative activity in the neighboring thymic cortex. Young adult mice were stimulated by an injection of aluminum phosphate-adsorbed tetanus toxoid into the peritoneal cavity which is known to be drained predominantly via parathymic lymph nodes. Animals were given an intravenous (i.v.) injection of deoxy(5-3H)cytidine and were killed 1 h later at various time points after priming. Combined morphometry, counts of cell numbers per unit area and radioautography revealed that a proliferative response of cortical thymocytes was confined to the vicinity of parathymic lymph nodes and peaked around day 14 after stimulation. It was also shown that the enhanced DNA synthetic activity took place in the subcapsular, outer zones rather than in the inner portions of the cortex. Results are discussed in the light of recent observations which demonstrated a translocation of small particles injected intraperitoneally (i.p.) into parathymic lymph nodes and the surrounding lymphatics, and from there, in small amounts, into the cortical parenchyma of the thymus. We conclude that cortical thymocytopoiesis can be enhanced in the segment adjacent to aprathymic lymph nodes as a result of i.p. injection of stimulants.

Animals↗
PubMed1986

[Does one become an alcoholic after age 60?].

The authors have examined all the patients which were older than 60 years and had been hospitalised for alcoholism over a span of 10 years and within a certain region. The study of their files shows that more than 70% had a previous history of alcoholism. The patients without history of alcoholism, displayed mostly depressive syndromes. The authors conclude that the occurrence of beginning of alcoholism after age 60 is possible but rare.

Aged↗
PubMed1985

Thymic lymphopoiesis: protected from, or influenced by, external stimulation?

The mechanisms regulating thymic lymphopoiesis are still a matter of debate. Intracortical proliferation and differentiation of thymocytes are thought to be controlled by locally produced humoral factors and close contact with epithelial, possibly also phagocytic, cells, and restricted by products of the major histocompatibility complex. The observation of a translocation of intraabdominally introduced PVP-coated silica particles (Percoll) via parathymic lymph vessels and through the thymic capsule into the cortical parenchyma demonstrates that the thymic cortex is accessible to materials carried with the transcapsular flux of interstitial fluid, and that this barrier is less effective than the blood-thymus barrier. The proliferative activity of cortical thymocytes following an intraabdominal injection of particulate tetanus toxoid was compared in sites adjacent to, and distant from, parathymic lymph nodes. Absolute numbers of DNA-synthesizing thymocytes were found to be much higher in cortical areas close to the lymph nodes, where lymphatic vessels are most numerous, than on the opposite sides of the thymic lobes. Taken together, these findings indicate that--in addition to intrinsic control mechanisms--cortical thymocyte production may be influenced by peripheral stimulation to some extent, and that materials from sites which are drained by parathymic lymph nodes may be important in this respect.

Animals↗
PubMed1984

A statistical analysis of Neanthes arenaceodentata, sister chromatid exchange data.

This paper presents a statistical evaluation of the sister chromatid exchange (SCE) assay using Neanthes arenaceodentata. Specific issues discussed are distribution of baseline SCE frequencies, transformations of SCE data, statistical sensitivity of the assay, repeatability of test results, and sources of variability of SCE data. Probabilities of false positives and false negatives are considered and recommendations are made for appropriate transformation of data, experimental design, and test conditions.

Analysis of Variance↗
PubMed1984

1-Acetyl-3-acetoxy-5'5-diphenylhydantoin has colchicine-like activity.

1-Acetyl-3-acetoxy-5'5-diphenylhydantoin (Ac-DPH) is a synthetic derivative of diphenylhydantoin with unusual properties: 1) it inhibits microtubular polymerization and depolymerizes established microtubules; 2) it blocks colchicine binding and displaces colchicine from microtubular protein, although it bears no resemblance to colchicine; and 3) it does not arrest human lymphocytes in metaphase, in contrast to diphenylhydantoin or its metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH).

Animals↗