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At least 433 records · Page 24Linked to original sources
PubMed1992

Reciprocal connections between the medial preoptic area and the midbrain periaqueductal gray in rat: a WGA-HRP and PHA-L study.

The midbrain periaqueductal gray (PAG) participates in diverse functions such as analgesia, autonomic regulation, sexual behavior, and defense/escape responses. Anatomical studies of the circuits involved in such functions have largely focused on the connections of PAG with the medulla. Projections to PAG from forebrain structures are extensive, but their organization has received little attention. Previous anatomic studies indicate that the medial preoptic area (MPO), involved in a variety of physiological and behavioral functions, is a major source of afferent input to the periaqueductal gray. Here, we have examined the topography of reciprocal connections between these two structures in the rat by using wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) and Phaseolus vulgaris leucoagglutinin (PHA-L). Multiple WGA-HRP injections at several rostrocaudal levels of PAG retrogradely labeled large numbers of neurons in the medial preoptic area; labeled cells were primarily located in the medial preoptic nucleus, the median preoptic nucleus, and the region lateral to the medial preoptic nucleus. The distribution of labeled cells shifted medially to laterally along the rostral to caudal axis of the medial preoptic area. Rostrally, there was selective retrograde labeling in the central and lateral divisions of medial preoptic nucleus, whereas caudally, labeled cells were primarily located only in the lateral subdivision of medial preoptic nucleus. Tracer injections in PAG also produced strong anterograde labeling in MPO. WGA-HRP and PHA-L injections in the medial preoptic area resulted in dense anterograde labeling along the entire rostrocaudal axis of PAG. The terminal labeling in PAG from the medial preoptic area was not uniformly distributed throughout PAG, however. Instead, this projection formed one or two rostrocaudally oriented longitudinal columns that terminated in different subregions of PAG along the entire rostrocaudal axis of this structure. Rostrally, inputs from the medial preoptic area project heavily to dorsomedial PAG, and at mid-PAG levels, the projection becomes distinctly bipartite with two discrete longitudinal terminal columns in dorsomedial and lateral PAG; caudally, the heaviest labeling is in ventrolateral PAG. The projection also exhibited a central to peripheral (radial) gradient; labelled fibers and terminals were heaviest near the aqueduct and much lower in the peripheral parts of PAG. WGA-HRP injections in MPO also produced retrograde labeling of neurons at all rostrocaudal levels of PAG; more neurons were labeled in the rostral than the caudal half of PAG. The majority of labeled cells were located in dorsomedial and ventral/ventrolateral parts of PAG; only a few neurons in the dorsal raphe region appear to project to MPO.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1993

Characterization of E-PHA-reactive alpha-fetoprotein isoforms by two-dimensional lectin affinity electrophoresis.

Erythroagglutinating phytohemagglutinin (E-PHA)-dependent isoforms of human alpha-fetoprotein (AFP) from cord blood were analyzed for their carbohydrate structures by two-dimensional electrophoresis with E-PHA combined with extended agarose gel electrophoresis or with affinity electrophoresis with concanavalin A or Allomyrina dichtoma lectin. By means of neuraminidase and/or beta-galactosidase treatment, AFP-P2 was identified as alpha 2-->6 disialo-AFP, AFP-P3 as having biantennary structures with alpha 2-->6 monosialylated galactose of the Mannose (Man) alpha 1-->6 arm, AFP-P4 as having alpha 2-->6 monosialylated galactose of the Man alpha 1-->3 arm, and AFP-P5 as disialo-AFP with alpha 2-->3 sialylated galactose of the Man alpha 1-->6 antenna with the alpha 2-->6 sialylated galactose of the other antenna. Desialylated AFP with the terminal galactose of the Man alpha 1-->6 antenna with or without the galactose of the other arm also had a migration of AFP-P4, and other hydrolytic intermediates without the terminal galactose of the Man alpha 1-->6 arm with and without the galactose of the other antenna had mobilities of AFP-P3s and AFP-P3, respectively. Thus, the present system of two-dimensional lectin affinity electrophoreses would provide a model for the determination of the sugar chain structure of glycoproteins.

Carbohydrate Conformation↗
PubMed1981

Stimulatory activity of PHA-LCM for normal human hemopoietic progenitors and leukemic blast cell precursors: separation by isoelectric focusing.

Medium conditioned by leukocytes in the presence of phytohemagglutinin (PHA-LCM) promotes growth of human hemopoietic progenitors (CFU-GEMM, BFU-E, CFU-C) and precursors of leukemic blast cells. PHA-LCM was separated by isoelectric focusing and each fraction tested with nonadherent cells of normal individuals as well as blast cells from two patients with acute myelogenous leukemia. Activity profiles for CFU-GEMM, BFU-E and CFU-C ranged form pH 5.0-6.5. The profile for activity stimulatory for leukemic blast cells was broader and ranged from pH 5.5-7.5. Although some overlap was observed, the main peaks of stimulatory activity for normally differentiating progenitors and precursors of leukemic blast cells were separable with respect to their isoelectric point.

Bone Marrow↗
PubMed1998

Differential display cloning of a novel human histone deacetylase (HDAC3) cDNA from PHA-activated immune cells.

The nucleosomal histones can be modified through reversible acetylation by histone acetyltransferases (HATs) and deacetylases (HDACs). HATs induce nucleosomal relaxation and allow DNA-binding by transcriptional activators. HDACs from corepressor complexes which negatively regulate cell growth. However, the HDAC inhibitors butyrate and Trichostatin A block T cell proliferation, suggesting that not all effects of HDACs lead to repression. Using mRNA differential display and 5'RACE we isolated human HDAC3, a novel gene that is upregulated in PHA-activated T cell clones. HDAC3 is homologous to other human HDACs and yeast RPD3. In peripheral blood mononuclear cells (PBMCs), activation by PHA, PMA and alpha-CD3 increased HDAC mRNA but no effect was seen with IFN-gamma, LPS, or IL-4. In contrast, GMCSF downregulated PBMC levels of HDAC3 mRNA. All HDACs were found to be ubiquitously expressed in immune and non-immune tissues. In human myeloid leukemia THP-1 cells, HDAC3 transfection resulted in increased size, aberrant nuclear morphology and cell cycle G2/M cell accumulation. Functional activity of the expressed HDAC3 protein was confirmed in alpha-HDAC3 antibody immunoprecipitates by a histone deacetylase assay. Our study suggests the participation of HDACs in cell cycle progression and activation.

Amino Acid Sequence↗
PubMed1999

Beta2-integrin, LFA-1, and TCR/CD3 synergistically induce tyrosine phosphorylation of focal adhesion kinase (pp125(FAK)) in PHA-activated T cells.

Complete T cell activation requires not only a first signal via TCR/CD3 engagement but also a costimulatory signal through accessory receptors such as CD2, CD28, or integrins. Focal adhesion kinase, pp125(FAK) (FAK), was previously shown to be localized in focal adhesions in fibroblasts and to be involved in integrin-mediated cellular activation. Although signaling through beta1- or beta3-integrins induces tyrosine phosphorylation of FAK, there has been no evidence that activation of T cells through the beta2-integrin, LFA-1, involves FAK. We report here that crosslinking of LFA-1 induces tyrosine phosphorylation of FAK in PHA-activated T cells. Moreover, cocrosslinking with anti-LFA-1 mAb and suboptimal concentration of anti-CD3 mAb markedly increases tyrosine phosphorylation of FAK in an antibody-concentration-dependent and time-kinetics-dependent manner compared with stimulation through CD3 alone, which correlates well with enhanced proliferation of PHA-activated T cells. Furthermore, LFA-1beta costimulation with CD3 induces tyrosine phosphorylation of Syk associated with FAK. These results indicate, for the first time, that signals mediated by LFA-1 can regulate FAK, suggesting that LFA-1-mediated T cell costimulation may be involved in T cell activation at least partially through FAK.

CD18 Antigens↗
PubMed1994

Study on the binding of lactotransferrin (lactoferrin) to human PHA-activated lymphocytes and non-activated platelets. Localisation and description of the receptor-binding site.

Fluorescein isothiocyanate derivatization of human lactotransferrin on Lys-264 as well as covalent addition of sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'- dithiopropionate (SASD)* on Lys-74 inhibits the binding of the glycoprotein to both human PHA-activated lymphocytes and non-activated platelets. This suggests that the cell binding site of lactotransferrin is located in the vicinity of the lysine residues 74 & 264 and does not occur either through electrostatic or lectin interactions. In contrast, the derivatization of lactotransferrin using sulfosuccinimidyl 6-(4'-azido-2'-nitrophenyl-amino) hexanoate (sulfo-SANPAH), on Lys-281 does not modify the binding parameters of lactotransferrin to the cells. Molecular modeling showed the position of SASD, sulfo-SANPAH and fluorescein molecules at the surface of the protein and suggested that SASD and fluorescein could mask the two loop-containing regions of human lactotransferrin (residues 28-34 and 38-45). Elsewhere, a 6 kDa peptide covering the peptide chain from residues 4 to 52 was isolated and its inhibitory effect on the binding of lactotransferrin to both human PHA-activated lymphocytes and non-activated platelets was demonstrated. Inhibition of ADP-induced platelet aggregation by lactotransferrin (50% inhibition = 10 nM) was also found with the N-t fragment of lactotransferrin (residues 3-281; 50% inhibition = 2 microM) and with two synthetic peptides: KRDS tetrapeptide (50% inhibition = 350 microM) and CFQWQRNMRKVRGPPVSC octodecapeptide (50% inhibition = 20 microM) corresponding to the lactotransferrin amino acid sequence 39-42 and 20-37, respectively.

Adenosine Diphosphate↗
PubMed1980

Immunotherapy versus chemotherapy of acute myeloid leukemia: response to PHA, allogeneic lymphocytes, and leukemic myeloblasts of remission lymphocytes from leukemia patients.

Lymphocytes were studied from 51 patients with acute myeloid leukemia (AML) in remission given chemotherapy (CT) maintenance alone or given chemoimmunotherapy (CIT) with BCG and viable allogeneic leukemic cells. CT lymphocytes reacted significantly more to PHA (P less than 0.05) if taken later than 100 days after remission than if taken earlier. CIT lymphocytes reacted less. Thus, the late CT lymphocytes reacted significantly more to nonspecific stimulators (PHA and allogeneic lymphocytes, P less than 0.01) than did late CIT lymphocytes or control lymphocytes. In consequence, the ratio of reactions to specific (leukemic myeloblasts) over nonspecific stimulators was significantly higher in CIT (P less than 0.01) than in CT lymphocytes. Results may indicate nonspecific immunostimulation during CT, and also some relative specific sensitization to allogeneic myeloblasts during CIT.

Antigens, Neoplasm↗
PubMed1978

Kinetics of 21-trisomic lymphocytes. I. In vitro response of 21-trisomic lymphocytes to PHA.

Data presented here on the quantitative 3H-thymidine incorporation into DNA, after PHA mitogenic stimulation, show that 21-trisomic lymphocytes are low-responders to PHA compared with the normal-diploid ones. Their responsiveness seems to decrease with the donor's age. Auto-radiographic studies clearly demonstrate that the fraction of labeled cells at the 72nd h of incubation is significantly smaller in the 21-trisomic lymphocyte population. The comparison of labeling indexes at different times of incubation (24, 48, 72 h) also indicate, in the same population, a slower increment of the portion of DNA-synthesizing cells. Discussing these data in the light of other's observations and recent progress in the knowledge of factors and mechanisms involved in the lymphocyte response to lectin mitogenic stimulus, it is suggested that differential distribution of T- and B- and/or T-cell subpopulations and a retarded cell induction time to proliferate may be two important factors negatively influencing the responsiveness of 21-trisomic lymphocyte population.

Adolescent↗
PubMed1981

Genetic analysis of human lymphocyte proteins by two-dimensional gel electrophoresis: 1. Detection of genetic variant polypeptides in PHA-stimulated peripheral blood lymphocytes.

Approximately 250 phytohemagglutinin (PHA)-stimulated peripheral blood lymphocyte polypeptides from three unrelated healthy males were compared by high-resolution two-dimensional gel electrophoresis and double-label autoradiography. Comparisons by all possible pairwise combinations of [14C]leucine-labeled proteins from an individual and [3H]leucine-labeled proteins from another revealed that only three polypeptides differed qualitatively among the three individuals. The degree of variation in lymphocyte polypeptides between different individuals was similar to that in fibroblast polypeptides reported previously. Among the three variant polypeptides, two polypeptides with mol. wt. 64,000 and mol. wt. 37,000 coexisted with a polypeptide with the same molecular weight, and they showed the behavior expected of two allelic gene products separated in the isoelectric focusing dimension by charge differences. Analysis of [14C]leucine labeled peripheral blood lymphocyte proteins, from the parents of each individual, by two-dimensional gel electrophoresis indicated that the variant polypeptides with mol. wt. 64,000 and mol. wt. 37,000 in the propositus were inherited from one of his parents. The data indicate that genetic analysis of PHA-stimulated peripheral blood lymphocyte proteins is feasible by high-resolution two-dimensional gel electrophoresis in combination with double-label autoradiography and pedigree analysis.U

Adult↗
PubMed1980

Effect of malathion on the genetic material of human lymphocytes stimulated by phytohemagglutinin (PHA).

This paper gives the results of studies on the effects of malathion on human lymphocytes stimulated by PHA, including cell survival, chromosomal aberration and nucleic acid content. Increasing malathion doses (10-70 micrograms/ml) were introduced into cultures of human lymphotyes at different times relative to the time of PHA addition. At a concentration of 10 micrograms/ml, malathion induced an increase in the RNA and DNA fractions in lymphocyte cultures. Higher malathion concentrations (50 and 70 micrograms/ml), especially the dose of 70 micrograms/ml, induced both a significant decrease in the content of RNA and DNA and reduced survival of cultured cells. The insecticide damaged the chromosome structure, but no correlation was revealed between the dose and the level of chromosome aberrations.

Cell Survival↗
PubMed1977

Differential chromosomal radiosensitivity within the first G1-phase of the cell cycle of early-dividing human leukocytes in vitro after stimulation with PHA.

Human leukocyte cultures were irradiated with 200 RX-rays before the addition of phytohemagglutinin (PHA) in the Go-stage and at different times up to 25 h within the first G1-phase of the cell cyle after the addition of PHA. The results of the analysis of chromosomal aberrations show that the frequencies of dicentric chromosomes increase significantly when leukocytes leave the Go-stage, reaching a miximum yield of aberrations about halfway through the first G1-phase. After that, toward the end of the G1-phase, the frequencies of dicentric chromosomes decrease again to a level similar to that found in the Go-stage. Different possible explanations for the differential chromosomal radiosensitivity of human leukocytes within the first post-stimulation G1-phase are discussed.

Chromosome Aberrations↗
PubMed1983

Defective T-cell response to PHA and mitogenic monoclonal antibodies in male homosexuals with acquired immunodeficiency syndrome and its in vitro correction by interleukin 2.

We studied the ability of phytohemagglutinin (PHA) and two anti-T-cell monoclonal antibodies OKT3 and Pan T2, to induce proliferation and interleukin 2 (IL2) production in peripheral blood lymphocytes (PBL) from 21 homosexual patients: 12 with Kaposi's sarcoma (KS), 4 with reactive lymphadenopathy, and 5 with opportunistic infections. All patients with KS and opportunistic infections had significantly lower mitogen-stimulated DNA synthesis, as compared to the controls, irrespective of the mitogen used (P less than 0.01). The patients with lymphadenopathy exhibited significantly lower responses only in the OKT3 assay as compared to normals (P = 0.009). The production of endogenous IL2 was significantly lower in PBL cultures from patients with KS and with opportunistic infections, irrespective of the mitogen used, as compared to healthy male controls, and also significantly lower in the Pan T2-stimulated cultures from patients with lymphadenopathy. The addition of highly purified IL2 was able to restore partially lymphocyte proliferation in vitro in the presence of these mitogens in all patients. Our studies demonstrate (1) that male homosexuals even without clinical manifestations of immunodeficiency frequently exhibit a proliferative T-cell defect when anti-T-cell monoclonal antibodies rather than PHA are used as mitogens, (2) that this proliferative defect is associated with defective IL2 production, and (3) that this defect is at least in part correctable in vitro by highly purified IL2.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Early effects and the possible mechanism of the effect of Concanavalin A (con A) and Phaseolus vulgaris lectin (PHA-P) on intestinal absorption of calcium and sucrose.

Food lectins are known to affect the absorption of nutrients in experimental animals and altered morphology of the intestinal mucosa due to prolonged feeding of lectins is suggested to be the cause. However, toxic symptoms appear in humans immediately after consumption of lectin rich foods and the mechanism of this immediate action is not known. This study reports the immediate effect of Concanavalin A (Con A) and Phaseolus vulgaris lectin (PHA-P) on the absorption of Ca2+ and sucrose in rat intestine and the possible role of lectin-membrane interactions in the process. Calcium absorption was lowered by Con A, and this was observed to be due to Con A interacting with the intestinal mucosal membrane. Similarly, sucrose absorption was also altered, probably due to Con A binding the intestinal mucosal membrane. On the other hand PHA-P did not have any effect on either sucrose or calcium absorption. Results indicate that the effect on intestinal nutrient absorption depends on the type of lectin used (and its concentration) as well as the type of nutrient, besides the duration of exposure of intestinal mucosa to the lectin.

Animals↗
PubMed1981

Stimulation of human T lymphocytes by PHA-activated autologous T lymphocytes: analysis of the role of Ia-like antigens with monoclonal antibodies.

Human T lymphocytes activated with PHA express Ia-like antigens and acquire the ability to stimulate autologous T lymphocytes in mixed lymphocyte reaction. This reaction is immunological in nature since it has specificity and memory. Ia-like antigens play a role in the stimulation of T lymphocytes by autologous PHA-T lymphocytes since monoclonal antibodies to Ia-like antigens can significantly, although not completely, inhibit the stimulation.

Antibodies↗
PubMed1983

Chemiluminescence response of human blood mononuclear cells to PHA and histamine.

Phytohaemagglutinin (PHA) elicited a short early chemiluminescence (CL) response of human blood mononuclear cells with a maximum at 2.5 min. The magnitude of the CL production was a function of the PHA concentration used. The CL response could be dose-dependently inhibited by histamine. In the presence of mepyramine the action of histamine was more pronounced while a dose-dependent reversal of the inhibition was found by cimetidine.

Cimetidine↗
PubMed1984

The effects of histamine H2-receptor antagonists on PHA induced lymphocyte proliferation.

Histamine H2-receptor antagonists must be used with caution to define the pharmacology of histamine effects on lymphocyte mitogenesis induced by PHA, because they can enhance and/or suppress in their own right, because these effects are similar to those of histamine itself, because mitogenic doses of PHA can release significant amounts of histamine from supposedly pure mononuclear cell preparations.

Burimamide↗
PubMed1981

Suppression of PHA-induced lymphocyte blastogenesis by concomitant presence of PPD in the culture.

PHA-induced lymphocyte blastogenic response was remarkably suppressed by the simultaneous presence of PPD in cultures of lymphocytes derived from individuals sensitized to PPD, but not affected by the presence of PPD when the cultures contained lymphocytes from an individual not sensitized to the protein. This double stimulation blastogenesis study with PHA and a specific antigen is feasible as a simple and rapid test to measure cell-mediated immunity to the antigen.

Antigens, Bacterial↗