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Biomedical subjects

P Bartmann

Publications and source records attributed to P Bartmann.

At least 91 records · Page 5Linked to original sources
PubMed1989

Peritoneal dialysis in the treatment of metabolic crises caused by inherited disorders of organic and amino acid metabolism.

Four neonates who presented with coma secondary to hyperammonaemia resulting in central respiratory failure were treated with peritoneal dialysis for between 16 and 120 hours. Underlying diseases were maple-syrup-urine disease, propionic acidaemia and citrullinaemia in two patients. Clinical improvement was observed in three patients within 16 to 72 hours after institution of peritoneal dialysis. Biochemical analysis revealed a rapid reduction in plasma concentration of leucine, isoleucine and valine as well as their alpha-keto-analogues in the infant suffering from maple-syrup-urine disease. Correction of ammonia, glycine, alanine and propionic acid concentrations was observed in the infant with propionic acidaemia 24-72 hours after institution of peritoneal dialysis. Severe hyperammonaemia (1,000-2,500mumol/l) in two infants with citrullinaemia before peritoneal dialysis was treated successfully in one infant; whereas the second infant showed no clinical improvement despite amelioration of biochemical parameters. Glucose-absorption from peritoneal dialysis solution was in the range of 216-441 mg/kg/h.

Amino Acid Metabolism, Inborn Errors↗
PubMed1989

[Disorders of immune function in children with selective IgA deficiency].

Numerous additional alterations of immune function in patients with selective IgA deficiency (serum IgA less than 0.05 g/l) have been described. In this group of patients we have investigated the connection with allergic diseases and alterations of the other immunoglobulin isotypes. Sera of 44 children from 1 3/12 to 18 years were analysed. In all patients serum IgA was below the nephelometric detection limit of 0.05 g/l). Using a more sensitive ELISA, IgA could be detected in all sera in concentrations ranging from 10 micrograms/l to 0.04 g/l. 25 children (57%) revealed a profound elevation of IgG serum levels, in 27 (61%) IgM was elevated above the upper age related normal value. In 7 patients (16%) with normal IgG serum levels a combined IgG2-IgG4 deficiency was found. In most cases these patients had unusually frequent and severe infections. Total IgE serum levels were determined by a RIA technique. In addition, an IgE-mediated sensitization to the most common food and inhalation antigens was detected by a standardized procedure (Phadiatop, Pharmacia). In 9/44 children (20%) IgE was less than 2 U/ml (lowest detection limit), 27 patients (62%) revealed levels of 6-86 U/ml within the age-related normal range. In 8 patients (18%) total IgE was above 381 U/ml. Four patients demonstrated a sensitization to inhalants, specific IgE antibodies to nutritive antigens were detected in three children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Undetectable IgG4 in immunoprecipitation: association with repeated infections in children?

A total of 210 patients with repeated infections were screened for IgG4 deficiency. In 30 patients (14%) IgG4 was undetectable by radial immunodiffusion (less than 30 mg/l). Of these patients 17 (57%) were less than 2 years of age. Concomitant IgA deficiency (IgA less than 0.05 g/l) was demonstrated in 11 cases (37%). IgG2 serum levels below the normal range were found in 26 children. IgG4 could be demonstrated at a concentration of 0.5-29 mg/l in all 30 patients using a more sensitive enzyme-linked immunosorbent assay technique. Although a highly selected group of patients was investigated, the percentage of individuals without detectable IgG4 by immunodiffusion was in the same range as reported in the literature for healthy control persons. It is thus concluded that IgG4 serum reference levels have to be defined using more sensitive methods and that the observed severe infections are more likely to be connected with low serum IgG2 and/or IgA levels than undetectable IgG4 as measured by immunodiffusion.

Adolescent↗
PubMed1988

[IgG subclass deficiency in childhood. Changes in the antigen specific immune response and significance of low IgG4 level].

The definition of IgG subclass deficiency and the correlations between low IgG subclass serum concentrations and high incidence of infections in certain patients are still obscure. Therefore 260 children from 6 months to 18 years with severe recurrent infections or a known immunodeficiency were screened for IgG subclass deficiency. Nine patients with severe IgG2 deficiency (Ig2 less than 0.3 g/l) and 35 patients with non-detectable IgG4 in immunoprecipitation were detected. One of these patients had a concomitant IgA deficiency, eight revealed an additional IgA and IgG2 deficiency, two an IgA, IgG2, and IgG3 deficiency, eighteen an IgG2 deficiency and one patient an IgG2 and IgG3 deficiency. The proportion of patients with non-detectable IgG4 in immunoprecipitation was 13.5% and thus in the same order of magnitude as described in the literature for healthy people. Our data show that there is no relation between low IgG4 serum levels and the increased occurrence of severe infections. In all patients investigated with non-detectable IgG4 in immunoprecipitation the gene for the heavy chain gene constant domain C gamma 4 could be detected by Southern blotting. Using a sensitive ELISA method IgG4 could be directly demonstrated in all patients at a serum level of 0.5-29 micrograms/ml. Specific IgG4 antibodies against protein antigens could not be detected in IgG4-deficient patients. Nevertheless total IgG antibodies against diphtheria and tetanus toxoid reached protecting titers. Patients with IgG2 deficiency showed an impaired immune response against polysaccharides from pneumococci and haemophilus influenzae type b.

Adolescent↗
PubMed1988

[Treatment of unilateral space-occupying pulmonary interstitial emphysema with positioning measures and high-frequency ventilation].

Five very low birthweight infants manifested unilateral tension pulmonary interstitial emphysema (PIE). All infants required intermittent positive pressure ventilation for respiratory distress syndrome. PIE was managed by positioning the infant on his (or her) side with PIE and by shortening the inspiratory time, in four patients also by shortening exspiratory time resulting in a higher frequency ventilation. PIE resolved within 3-6 days after institution of this treatment. This was paralleled by a reduction of FiO2 as well as peak inspiratory pressures. All infants could successfully be extubated 2-6 weeks after birth.

Combined Modality Therapy↗
PubMed1985

In vitro maturation of B cells in chronic lymphocytic leukemia. I. Synergistic action of phorbol ester and interleukin 2 in the induction of Tac antigen expression and interleukin 2 responsiveness in leukemic B cells.

Recent evidence indicates that interleukin 2 (IL 2), formerly thought to serve as growth factor exclusively for activated T cells, is directly involved in human B cell differentiation. We have investigated the role of IL 2 and IL 2 receptors (as defined by monoclonal anti-Tac antibody) in the phorbol ester-induced in vitro maturation of leukemic B cells from patients with chronic lymphocytic leukemia (CLL). Peripheral blood lymphocytes from B cells from CLL patients with high (greater than 10(5)/microliters) white blood cell counts were depleted of residual T lymphocytes and low-density cells (primarily macrophages) by consecutive steps of E rosetting, complement-mediated lysis of OKT3+ and OKT4+ cells, and Percoll density gradient centrifugation. No OKT3+ T cells were detectable in these cell populations before or after culture. When incubated for 3 days with phorbol ester plus recombinant human IL 2 (rIL 2), 12 to 57% of highly purified B cells from four of five tested patients expressed Tac antigen. Both phorbol ester and rIL 2 were required for maximal Tac antigen expression. Functional studies revealed that phorbol ester-activated (but not resting) CLL B cells responded to rIL 2 with [3H]thymidine incorporation and with enhanced secretion of IgM. Tac+ B cells were isolated in two cases on a fluorescence-activated cell sorter. In one patient, stimulation of Tac+ B cells with rIL 2 resulted in enhanced [3H]thymidine incorporation but no change in IgM secretion, as compared with Tac- B cells; in the second patient, stimulation of Tac+ B cells with rIL 2 did not result in [3H]thymidine uptake, but did result in significant IgM secretion. These findings indicate that certain leukemic B lymphocytes can be induced to express IL 2 receptors and respond to IL 2. The use of resting clonal B cell populations arrested at distinct stages of differentiation may help to better define the stage(s) at which IL 2 acts directly on B cells to induce proliferation and/or terminal differentiation.

Antibodies, Monoclonal↗
PubMed1983

[Neonatal leukemoid reaction caused by prenatal corticoid administration?].

A leukemoid reaction in the neonatal phase of a preterm infant is described. After a maximum of 112,000/microliter at the forth day leukocyte concentration normalized during the end of the second week of life. Intensive investigations could reveal none of the known causes of leukocytosis. The connection with maternal corticoid administration to prevent respiratory distress syndrome is discussed.

Adult↗
PubMed1980

[Isolation and identification of antigen-specific T-cell-receptors (author's transl)].

Experimental allergic encephalomyelitis was induced by injection of myelin basic protein into guinea pigs strain 13. Specific antigen binding T-cell receptors were isolated by means of a nylon net coupled with antigen. A phage immunoassay was set up as an analytical tool for detection of the receptors. They were found not to be identical with common immunoglobulins and have a molecular weight of 71,000.

Animals↗
PubMed1975

L-phenylalanine:tRNA ligase of Escherichia coli K10. A rapid kinetic investigation of the catalytic reaction.

The kinetics of the amino acid activation and the transfer of the amino acid to tRNA have been investigated for L-phenylalanine:tRNA ligase of Escherichia coli K10 by stopped-flow and radioactive techniques. The rapid kinetics were followed by the observation of the displacement of the fluorescent dye, 6-p-toluidinylnaphthalene-2-sulfonate from the binding site of L-phenylalanine under conditions where a single active site of the enzyme was involved. The following results are of particular interest. (1) Equilibrium binding of L-phenylalanine and tRNAPhe indicates in each case two sites of interaction with an approximately tenfold difference of the binding affinity. (2) Experimental conditions of the kinetic investigation were chosen to favor reactions at the high affinity binding sites. Under those conditions, the rate constants have been evaluated at 1 mM magnesium to be in the range 12-25 sec-1 for the activation reaction and 42-77 sec-1 for the reverse, the variation of the values depending on those of the dissociation constants used for computation. The rate constant for the transfer reaction is 0.05 sec-1 and for the reverse 0.19 sec-1. The forward reaction is rate limiting for the overall reaction at single turnover and steady-state conditions. (3) All rate constants depend on the concentration of magnesium. Evidence is provided that the transfer occurs via a productive enzyme-tRNAPhe complex which is in a magnesium-dependent equilibrium with an unproductive complex, high magnesium favoring the former. The position of the tRNA-CCA end in the productive complex is such, that the fluorescent dye can be displaced by Phe-tRNAPhe. The thermodynamics of the overall reaction have been treated on the basis of the partial reactions. The free enthalpy of the completed reaction was calculated to be very close to zero. The significance of the adenylate intermediate is discussed with respect to the product inhibition expected on the basis of the tendency of tRNAPhe and L-phenylalanine to form tight complexes with the enzyme.

Adenosine Triphosphate↗
PubMed1975

Active site stoichiometry of L-phenylalanine: tRNA ligase from Escherichia coli K(-10).

The existence of two active siter per molecule of L-phenylalanine:tRNA ligase from Escherichia coli K(-10) has been demonstrated by isolation of the E-aminoacyl adenylate and tel filtration and the nitrocellulose filter assay at pH 5.0 revealed the same stoichiometry for the E-tRNAPhe comples as protection against degradation by snake venom phosphodiesterase and equilibrium gel filtration at pH 7.5. Using a fluorescence titration technique, it was found that the dissociation constant for ligase-tRNAPhe complex is decreased 20-fold when the hydrogen ion concentration is changed from pH 6.0 to pH 5.0. The existence of two active sites binding the aminoacyl adenylate intermediate was demonstrated by gel filtration and retention on DEAE-cellulose filters. "Burst" experiments indicated that two sites were involved in a rapid ATP consumption at conditions of catalytic amino acid activation. Furthermore, it was observed that the activated amino acid could be transferred from both sites to cognate tRNA.

Adenosine Triphosphate↗
PubMed1975

The catalytic mechanism of amino acid:tRNA ligases. Synergism and formation of the ternary enzyme-amino acid-ATP complex.

Formation of binary and ternary enzyme-ligand complexes was investigated for amino acid:tRNA ligases specific for L-isoleucine, L-leucine, and L-phenylalanine. Each of the enzymes exhibited synergistic binding when a substrate was substituted by a structurally related compound. The strength of coupling between the sites binding the amino acid and ATP was strongly dependent on the structure of ligands. The phenomenon was observed with the L-leucine and L-phenylalanine-specific enzymes only in the presence of magnesium. Spermine was inhibitory for L-phenylalanine:tRNA ligase. From the variation which structure of the strength of the observed synergism a correlation scheme was derived considering the ammonium group, the carboxylate group and the side chain of the amino acid, and the adenosine and triphosphate moieties of ATP. The strength of coupling between the subsites binding various combinations of these moieties was evaluated. We found that binding of the subgroups of the amino acid exerts an intramolecular synergism. The strength intramolecular synergism was similar to the strength of the intermolecular synergism observed for the simultaneous binding of an amino alcohol and ATP (or MgATP-2-). We have derived a molecular mechanism for the formation of the ternary enzyme-amino acid-ATP (or MgATP-2-) complex taking into account the synergistic phenomena. The complex is considered to involve electrostatic repulsion between the amino acid carboxylate and the ATP triphosphate moieties. When one of the negatively charged groups have been eliminated, the enzymatic rearrangement which facilitates the formation of this complex may be seen as a synergistic coupling.

Adenosine↗