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Biomedical subjects

C Heilmann

Publications and source records attributed to C Heilmann.

125 records · Page 7Linked to original sources
PubMed1984

Secretion of immunoglobulins and IgM rheumatoid factor by pokeweed mitogen-induced blood lymphocytes: an evaluation by plaque forming cell assays.

The numbers of pokeweed mitogen (PWM)-induced IgM-, IgG- and IgA-secreting cells (SC) in mononuclear cell cultures from patients with seropositive and seronegative rheumatoid arthritis (RA) were reduced compared to those of control persons. Significant numbers of IgM rheumatoid factor (RF)-SC were only found in PWM-induced cultures from patients with seropositive RA (median: 7 IgM RF-SC/10(6) and controls greater than or equal to 50 years (median: 6 IgM RF-SC/10(6). The ratio of IgM RF-SC to total IgM-SC (RF/IgM-SC ratio) was significantly higher in patients with seropositive RA (median: 0.6%) than in controls greater than or equal to 50 years (median: 0.1%). Patients with seropositive RA and RF/IgM-SC ratios above 0.5% had higher Waaler-Rose titers than those with ratios under 0.5%. Our results indicate that secretion of Ig by PWM-induced blood lymphocytes is suppressed in patients with RA compared to controls; in seropositive RA a higher fraction of in vitro activated IgM-SC secrete IgM RF as compared to controls and patients with seronegative RA.

Adult↗
PubMed1983

The phosphoprotein intermediate of a Ca2+ transport ATPase in rat liver endoplasmic reticulum.

Smooth endoplasmic reticulum vesicles from rat liver display an ATP-supported Ca2+ transport which is mediated by a (Ca2+ + Mg2+)-ATPase. During the catalytic cycle the terminal phosphate from ATP is incorporated to form an acid-precipitable reaction product(118 000-Mr in SDS-gel electrophoresis) with stability characteristics of an acylphosphate. Comparative studies with sarcoplasmic reticulum vesicles from fast-twitch skeletal muscle suggest that the 118 000-Mr phosphopeptide may be identified with the phosphorylated reaction intermediate of a Ca2+ transport ATPase in endoplasmic reticulum, similar to that in sarcoplasmic reticulum of muscle.

Adenosine Triphosphatases↗
PubMed1983

IgG rheumatoid factor-secreting lymphocytes in rheumatoid arthritis: evaluation of a haemolytic plaque-forming cell technique.

A haemolytic plaque-forming cell (PFC) assay detecting human B lymphocytes secreting IgG rheumatoid factor (RF) was established using sheep erythrocytes (SRBC) sensitized with rabbit IgG, developing rabbit anti-human IgG, and complement. IgG-RF PFC were only demonstrated with IgG-depleted guinea-pig serum as the source of complement. Cells spontaneously secreting IgG-RF were found among synovial fluid mononuclear cells (mean, 134/10(6)) and synovial tissue mononuclear cells (mean, 1775/10(6)) from patients with rheumatoid arthritis, whereas few were recorded among blood lymphocytes (mean, 3/10(6)). The experiments revealed that the RF-IgG PFC were protein-synthesizing B lymphocytes. The antibody specificity of the secreted IgF-RF was verified by the inhibitory effect of exogenous human and rabbit IgG on PFC formation.

Animals↗
PubMed1983

Secretion of IgM-rheumatoid factor and IgM by blood lymphocytes in rheumatoid arthritis.

A direct plaque forming cell (PFC) assay for the detection of complement fixing IgM-rheumatoid factor (RF) secreting lymphocytes was evaluated. The specificity of the RF-PFC assay was demonstrated by the inhibitory action of exogenous human IgG. The sensitivity of the RF-PFC assay was similar to that of a reverse PFC assay detecting all cells secreting IgM (IgM-PFC). In blood from 75% of seropositive patients with rheumatoid arthritis (RA) RF-PFC were demonstrated, median value 6.8 (range: 0.4-1477) RF-PFC/10(6) mononuclear cells. Practically no RF-PFC were detected in seronegative RA patients and controls. Despite the fact that most IgM-RF undoubtedly is produced outside the blood, a positive correlation was found between the number of RF-PFC and the Waaler-Rose titer in serum. The number of circulating IgM secreting cells did not differ significantly between seropositive RA patients, seronegative RA patients and controls. Comparison of RF-PFC and IgM-PFC in seropositive patients revealed that in mean 7% of IgM-secreting cells in blood secrete IgM-RF.

Antibody Specificity↗
PubMed1980

Granulocyte function in children with acute lymphoblastic leukaemia during remission.

The granulocyte function of 20 children with acute lymphoblastic leukaemia was studied during remission and compared to that of 20 health adults. Granulocyte function was equally decreased when examined in patient serum and pooled normal serum, The decreased bactericidal function was predominantly due to reduced intracellular killing. Patients with grossly reduced granulocytic function had more infections than the rest of the group, though the difference was not statistically significant.

Adolescent↗
PubMed1980

Severe combined immunodeficiency associated with hyperimmunoglobulinaemia E, eosinophilia and impaired neutrophil chemotaxis.

A boy with severe combined immunodeficiency was found to have coexistent hyperimmunoglobulinaemia E, eosinophilia and impaired neutrophil chemotaxis. Based on the literature, a deficient regulatory function of the T-cell system is proposed as the basic defect leading to the observed impairment of the cellular and humoral immunity and, probably through hyper-immunoglobulinaemia E, to defective neutrophil chemotaxis.

Chemotaxis, Leukocyte↗
PubMed1979

Molecular transformations in sarcoplasmic reticulum of fast-twitch muscle by electro-stimulation.

Chronic electro-stimulation of fast-twitch rabbit muscle with the frequency pattern received by a slow-twitch muscle induces a progressive transformation of the sarcoplasmic reticulum. After 2 days stimulation activities of Ca2+-dependent ATPase and of Ca2+ transport begin to decrease, and are paralleled by a progressive decrease in Ca2+-dependent and Ca2+, Mg2+-dependent phosphoprotein formation, reduced rate of dephosphorylation and a rearrangement of the electrophoretic polypeptide and phosphoprotein patterns. These findings suggest a transformation of the sarcoplasmic reticulum to resemble that of a slow-twitch muscle. This transformation is paralleled by increase in time-to-peak of twitch contraction and half relaxation time and occurs before conversion of the myosin light chain pattern is observed. The parallel time course of changes in contractile properties of stimulated muscle and the molecular and functional properties of the sarcoplasmic reticulum emphasizes the definitive role of the latter in determining the twitch characteristics of fast and slow twitch muscles.

Adenosine Triphosphatases↗
PubMed1977

ATPase activities, Ca2+ transport and phosphoprotein formation in sarcoplasmic reticulum subfractions of fast and slow rabbit muscles.

Subfractionation of sarcoplasmic reticulum from fast-twitch and slow-twitch rabbit skeletal muscles was performed on a sucrose density gradient. Vesicle fractions were characterized by: measurement of (Ca2+,Mg2+)-dependent (extra) ATPase, Mg2+-dependent (basal) ATPase, Ca2+ uptake characteristics, polypeptide patterns in sodium dodecylsulphate polyacrylamide gel electrophoreses, phosphoprotein formation and electronmicroscopy of negatively stained samples. In fast-twitch muscle, low and high density vesicles were separated. The latter showed high activity of (Ca2+,Mg2+)-dependent ATPase, negligible activity of Mg2+-dependent ATPase, high initial rate and high capacity of Ca2+ uptake, high amount of phosphorylated 115000-Mr polypeptide, and appeared morphologically as thin-walled vesicles covered with particles of 4 nm in diameter. Low density vesicles had little (Ca2+,Mg2+)-dependent ATPase but high Mg2+-dependent ATPase. Although the initial rate of Ca2+ uptake was markedly lower, the total capacity of uptake was comparable with that of high density vesicles. Phosphorylated 115000-Mr polypeptide was detectable at low concentrations. Instead, 57000 and 47000-Mr polypeptides were characterized as forming stable phosphoproteins in the presence of ATP and Mg2+. Negatively stained, these vesicles appeared to have smooth surfaces. It is suggested that low density vesicles represent a Ca2+ sequestering system different from that of high density vesicles and that Mg2+-dependent (basal) ATPase as well as the 57000 and 47000-Mr polypeptides are part of the Ca2+ transport system within the low density vesicles. According to the results from slow-twitch muscle, Ca2+ sequestration by the sarcoplasmic reticulum functions in this muscle type only through the low density vesicles.

Adenosine Triphosphatases↗
PubMedDate not supplied

Transformation of morphological, functional and metabolic properties of fast-twitch muscle as induced by long-term electrical stimulation.

Transformation of structural, functional, metabolic and molecular characteristics is induced by stimulating fast-twitch muscles with the frequency pattern of a motoneuron normally innervating a slow-twitch muscle. These changes correspond to a transition of a "fast-white" into a "slow-red" muscle. Intermittent stimulation (8 h/d) does not affect the system but causes alterations of the sarcoplasmic reticulum which lead to changes in time to peak and half relaxation time. Continuous stimulation (24 h/d) induces a transformation of the muscle also at the level of the myosin system.

Animals↗
PubMedDate not supplied

Characterization of cardiac microsomes from spontaneously hypertonic rats.

Capacity of Ca2+ sequestration was found to be significantly lowered in microsomal preparations of hearts from spontaneously hypertonic rats. A decrease to 40% of the control level was found for basal and extra ATPase. A similar reduction existed in initial and total Ca2+ uptake. These findings are correlated with a lower concentration of the Ca2+ transport ATPase in SDS gel electrophoresis, a lower density of the 7-9 nm intramembraneous particles and higher half-lives of phosphoprotein. Altered contractility of hypertrophied myocardium may thus be partially explained by the dysfunction of the Ca2+ sequestering system.

Adenosine Triphosphatases↗
PubMedDate not supplied

The role of monocytes and T cells in 1,25-dihydroxyvitamin D3 mediated inhibition of B cell function in vitro.

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) inhibits immunoglobulin production by human mononuclear cells (MNC) in vitro. The present study was undertaken to evaluate the role of T cells and monocytes in 1,25-(OH)2D3 induced suppression of B cell functions. The synthetic vitamin D3 analogue MC 903 was examined in parallel. 1,25-(OH)2D3 and MC 903 showed a dose-related inhibition of IgM, IgG and IgA plaque-forming cells in poke-weed mitogen (PWM) activated cultures of MNC. This effect was most likely mediated through impairment of T cell and monocyte functions. First, the inhibitory effect was seen after PWM stimulation, but not after Epstein-Barr virus stimulation which activates B cells independently of T cells and monocytes. Second, 1,25-(OH)2D3 was not effective in T cell and monocyte-depleted cultures. Third, the effect of 1,25-(OH)2D3 on PWM driven MNC was reversed by addition of the recombinant monokines: interleukin (IL)-1 beta, tumour necrosis factor alpha (rTNF alpha), rIL-6, as well as the lymphokines: lymphotoxin (rLT) and rIL-2. This is consistent with the finding that 1,25-(OH)2D3 also inhibited IL-1 alpha, TNF alpha and LT production in these cultures. The assumption that B cells are not directly affected by 1,25-(OH)2D3 was further supported by the fact that 24 h of culture with 10(-8) M 1,25-(OH)2D3 failed to reduce immunoglobulin production by in vivo activated B cells.

Antibody Formation↗