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Biomedical subjects

H Fricke

Publications and source records attributed to H Fricke.

At least 73 records · Page 4Linked to original sources
PubMed1990

Methanococcus igneus sp. nov., a novel hyperthermophilic methanogen from a shallow submarine hydrothermal system.

A novel hyperthermophilic strictly chemolithoautotrophic member of the genus Methanococcus was isolated from a shallow (depth: 106 m) submarine vent system at the Kolbeinsey ridge, Iceland. The isolate grew between 45 and 91 degrees C with an optimum around 88 degrees C (doubling time: 25 min). It differs from Methanococcus jannaschii in its 16S rRNA sequence, its non-hybridizing DNA, and its selenium-independent growth. Therefore, the isolate represents a new species which we name Methanococcus igneus. Type strain is isolate "Kol 5" (DSM 5666).

Archaea↗
PubMed1990

Monoclonal anti-La antibody derived from a mouse with experimental SLE is similar to human anti-La antibodies.

The La antigen is a highly conserved protein, originally defined by sera of patients with Sjögren's syndrome or systemic lupus erythematosus (SLE). In the present study, we have produced and characterized a monoclonal anti-la antibody derived from mice with experimental SLE. The induction of SLE in these mice was achieved by their immunization with a murine monoclonal anti-idiotypic antibody against a common idiotype (16/6 Id) found in SLE patients. The monoclonal anti-La antibody derived from these mice was found to be virtually identical to the anti-La antibodies found in human autoimmune sera. First, its binding to different nuclear extracts, as well as to protease-digested HeLa nuclear protein extracts, was found to be identical to that of human anti-La antibodies. Second, an inhibition study on blotted proteins demonstrated a very close relationship between the epitopes recognized by the murine monoclonal anti-La antibody and the human anti-La serum. Third, the monoclonal anti-La antibody was found by immunofluorescence to be directed against a nuclear antigen that gave a speckled pattern. Finally, the monoclonal anti-La antibody immunoprecipitated the La-associated small RNAs. This report provides evidence for the similarity of murine anti-La antibody produced in experimental SLE and human anti-La antibodies formed in autoimmunity.

Animals↗
PubMed1990

Induction of experimental systemic lupus erythematosus in mice by immunization with a monoclonal anti-La autoantibody.

Experimental systemic lupus erythematosus (SLE) in mice can be induced by immunization either with a human monoclonal anti-DNA antibody bearing the 16/6 idiotype (16/6 Id) or with a mouse monoclonal anti-idiotypic antibody specific for the 16/6 Id. In the present report we investigated the pathogenic role of a monoclonal anti-La autoantibody in the induction and mediation of experimental SLE in mice. The monoclonal anti-La antibody was derived from a mouse in which experimental SLE was induced by immunization with the monoclonal anti-16/6 Id antibody. Following immunization with the anti-La antibody the mice produced antibodies to double-stranded DNA, single-stranded DNA, Sm, SS-A/Ro, SS-B/La, and ribonucleoprotein. Furthermore, even though the anti-La antibody does not express nor react with the 16/6 Id, the immunized mice produced high titers of anti-16/6 Id antibodies as well as 16/6 Id bearing antibodies. Four months following immunization the mice exhibited significant proteinuria, and kidney sections revealed immune complex deposits on the basement membrane of the glomeruli. These results suggest that anti-La autoantibodies are involved in the induction and mediation of SLE in mice.

Animals↗
PubMed1990

The importance of the pathogenic 16/6 idiotype in the induction of SLE in naive mice.

We have previously demonstrated the pathogenicity of the common anti-DNA idiotype designated 16/6 Id. Immunization of naive mice with the 16/6 Id induced SLE-like disease characterized by serological (e.g. anti-dsDNA and anti-Sm auto-antibodies), clinical (increased ESR, leucopenia and proteinuria), and pathological (16/6 Id deposition in kidneys) parameters. To elucidate further the role of the 16/6 Id in SLE induction the following studies were carried out: BALB/c mice were immunized with SA-1, a human anti-DNA monoclonal antibody carrying the 16/6 Id; TB-68, a mouse monoclonal anti-tuberculosis (TB) glycolipid, which binds dsDNA and carries the 16/6 Id; TB-72, a mouse monoclonal anti-TB glycolipid that binds DNA and does not harbour the 16/6 Id; and 4B4, a human anti-Sm antibody that carries the 16/6 Id. SLE was induced in BALB/c mice only when immunized with SA-1, TB-68, and 4B4, namely antibodies with diverse binding capacities albeit having the 16/6 Id. Our studies further support previous evidence on the pathogenic role attributed to the 16/6 Id in SLE, and suggest that SLE is most probably an idiotype-induced disease.

Animals↗
PubMed1990

The genetic regulation of the induction of experimental SLE.

We have recently reported the induction of systemic lupus erythematosus (SLE) in C3H.SW female mice by their immunization with a human monoclonal anti-DNA antibody that bears a common idiotype termed 16/6 Id. In the present study, the ability to induce experimental SLE in seven inbred mouse strains by immunization with the 16/6 Id was examined. Two out of the seven strains failed to develop the disease. These two strains did not produce antibodies specific to the 16/6 Id, while the other five strains produced high titres of anti-16/6 Id antibodies. The anti-16/6 Id antibody response, followed by the induction of the disease, was not found to be MHC or Ig heavy chain allotype linked. F1 hybrids between a resistant strain and two of the susceptible strains were found to be resistant to the induction of the disease, indicating that susceptibility is inherited as a recessive trait. In the autoimmune NZB/W F1 female mice, immunization with the 16/6 Id resulted in an early onset of the SLE-like disease. The results of the present study indicate the role of the anti-16/6 Id antibodies in the induction of experimental SLE, and provide direct evidence for the importance of the genetic background in determining susceptibility to SLE.

Animals↗
PubMed1990

Sex hormone involvement in the induction of experimental systemic lupus erythematosus by a pathogenic anti-DNA idiotype in naive mice.

The effect of sex hormones on the induction of experimental systemic lupus erythematosus (SLE) with a human anti-DNA (16/6 Id +) antibody, was studied. We found that injection of the pathogenic idiotype to BALB/c females and orchiectomized males treated with estrogen caused a rapid outburst of the disease 3 months after immunization, while nonestrogen treated mice developed the disease 5 months after immunization. The flare of SLE disease was characterized by raised levels of autoantibodies in the sera to dsDNA, histones, cardiolipin, Sm, RNP, SSA (Ro), SSB (La) and an emergence of high titers of mouse antibody carrying the 16/6 Id. These enhanced antibody levels were associated with an increase in erythrocyte sedimentation rate, proteinuria and leukopenia. Immunofluorescent studies confirmed the existence of immune complexes in the afflicted kidneys. Testosterone treated BALB/c females and orchiectomized males developed a classical response to the human anti-DNA antibody (16/6 Id +), but failed to develop fulminant SLE-like disease. Our data demonstrate the importance of sex hormones on the induction of experimental SLE-like disease in mice with no genetic tendency to autoimmunity.

Animals↗
PubMed1989

The role of anti-idiotypic antibodies in the induction of experimental systemic lupus erythematosus in mice.

We have recently reported the induction of experimental systemic lupus erythematosus (SLE) in mice by a human anti-DNA monoclonal antibody (mAb) that bears a common idiotype, the 16/6 Id. In the present report we investigated the role of the idiotypic network in the induction of experimental SLE by using a murine anti-idiotypic mAb specific for the 16/6 Id. This anti-idiotypic mAb induced experimental SLE similarly to the 16/6 Id. Thus, following immunization, in addition to 16/6 Id+ antibodies, the mice produced antibodies to various nuclear antigens: single-stranded DNA, double-stranded DNA, poly(I), poly(G), Ro, La, Sm and ribonucleoproteins. Similarly to the 16/6 Id-immunized mice, the mice injected with the anti-16/6 Id mAb exhibited elevated erythrocyte sedimentation rate and leukopenia. The murine anti-16/6 Id mAb was found to be more effective than the 16/6 Id, in causing earlier onset of proteinuria and renal damage. These results suggest that the idiotypic network and particularly anti-idiotypic antibodies specific for anti-DNA common idiotypes found in SLE, play an important role in the induction of SLE in mice.

Animals↗
PubMed1989

[Rationalization of the double-antibody ELISA for cortisol determination from microtest plates using the Sumal system].

A method for enzyme-immunologic determination of cortisol by double-antibody-precipitation using microtest plates instead of centrifuge-glass-tubes is presented. By the use of highly productive technology, e.g. the Sumal-system, connected with accession to computer-techniques, the demand for workers is considerable reduced, especially with analyses of greater series. Another advantage is the reduction of the demand for biochemicals to 20%.

Computers↗
PubMed1986

Biosynthetic preparation of radioactively labelled ethanolamine plasmalogen (1-O-[1'-14C]octadec-1'-enyl-2-acyl-sn-glycero-3-phosphoethanola mine) using a protozoan cell culture.

Ethanolamine plasmalogen radiolabelled mainly in the O-alkenyl moiety was prepared from cell suspension cultures of the flagellate Leishmania donovani previously incubated with [1-14C]octadecanol over one growth period. The optimal concentration of [1-14C]octadecanol for labelling was shown to be 1 microM, when 60% of total lipid radioactivity appeared in the 1,2-diradyl-sn-glycero-3-phosphoethanolamine fraction, with an overall yield of approx. 35%. Analysis of this fraction revealed that 93% of the label was present in O-octa-dec-1-enyl, 3% in O-alkyl and 4% in acyl moieties. A specific radioactivity of approx. 14 mCi/mmol was determined. Raising the culture medium concentration of [1-14C]octadecanol to 2 microM yielded a product with a specific radioactivity of 25 mCi/mmol.

Animals↗
PubMed1984

Synthesis and evaluation of luminescent tracers and hapten-protein conjugates for use in luminescence immunoassays with immobilised antibodies and antigens. A critical study of macro solid phases for use in immunoassay systems, Part II.

This article describes the synthesis of labels and hapten-protein conjugates for use in bio- and chemiluminescent immunoassay systems, together with the problems encountered. The effects of maleimide upon acetate-, adenylate- and pyruvate kinase activity have been studied, as well as upon the luciferin-luciferase monitoring system. Maleimide inhibited both acetate and adenylate kinase but showed no inhibition of pyruvate kinase and the monitoring reagent. Four heterobifunctional reagents were tested for their capability in forming pyruvate kinase-donkey-anti-rabbit IgG conjugates which retained enzyme and antibody activity. The best results were obtained with succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate and succinimidyl-6-(p-maleimidophenyl)-hexanoate. The relationship between the amounts of succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate and IgG was studied with respect to enzymic activity of the conjugate. The Michaelis-Menten constants for both conjugated and non-conjugated pyruvate kinase were calculated and compared. It was found that the maximal velocity (Vmax) of the conjugated enzyme was lower than that of the non-conjugated enzyme although the "apparent" Km value was the same for both conjugated and non-conjugated pyruvate kinase. The pyruvate kinase-anti rabbit IgG conjugate was tested for its ability to bind to rabbit-IgG coated polystyrene balls. In addition to bioluminescent labels, the synthesis of chemiluminescent markers was undertaken and optimised. The three substances used for labelling were diazoluminol, diazoisoluminol and N-(4-aminobutyl)-N-ethylisoluminol hemisuccinamide the latter being used as an N-hydroxysuccinamide "active" ester. The ratio of label to IgG was studied for diazoluminol and N-(4-aminobutyl)-N-ethylisoluminol hemisuccinamide active ester after it had been discovered that diazoisoluminol was not suitable for coupling to antibodies. The optimal molar ratios label: IgG were for diazoluminol 40:1 and for N-(4-aminobutyl)-N-ethylisoluminol hemisuccinamide active ester 60:1. Increasing the substitution rate led to a lessening of the dynamic range, shown by an increase in the ratio between unspecific binding (noise) to maximal binding (signal) in an assay. The synthesis of hapten-protein conjugates for covalent coupling to polystyrene balls was undertaken as this formed part of the preparation for the assays described in Part III. The optimal production of gentamicin-bovine serum albumin and thyroxine-transferrin conjugates has been described in detail.

Animals↗
PubMed1984

An evaluation of four different luminescence immunoassay systems: CELIA (chemiluminescent immunoassay), SPALT (solid-phase antigen luminescence technique), ILMA (immunoluminometric assay) and ILSA (immunoluminometric labelled second antibody). A critical study of macro solid phases for use in immunoassay systems, Part III.

The performance of different solid-phase luminescence immunoassays has been documented using four different assay concepts. These are CELIA (chemiluminescence immunoassay), SPALT (solid-phase antigen luminescence technique), ILMA (immunoluminometric assay) and ILSA (immunoluminometric labelled second-antibody assay). CELIA is analogous to a solid-phase radioimmunoassay and uses a labelled antigen, SPALT and ILSA use a labelled second (species-specific) antibody and ILMA a labelled substance-specific antibody, i.e. analogous to the immunoradiometric assay. Both bioluminescent and chemiluminescent labels have been used. Pyruvate kinase was used for bioluminescence and diazoluminol and N-(4-amino-butyl)-N-ethyl isoluminol hemisuccinamide for chemiluminescence. Relevant quality-control parameters and reference ranges have been given for the optimised assays. Assays described are: thyroxine, thyroxine binding globulin, cortisol, caeruloplasmin, ferritin and C-reactive protein. Luminescence immunoassays with coefficients of variation comparable with radioimmunoassay have been designed, values of under 5% being obtainable within the working range of the assay.

Animals↗
PubMed1983

[Protein binding of the macrolide antibiotic turimycin. Methodologic effects on results].

A methodological investigation deals with the binding of the macrolide antibiotic turimycin to bovine serum albumin (BSA) and serum proteins. On this occasion, it is pointed out that, especially when serum is used, the critical evaluation of the analytical method is of the same importance as the utilization of standardized procedures for the quantification of the protein binding in the sense of general comparability. This concerns, for example, the chemistry of the reaction used for detection, the formation of degradation products of the active principle in the serum during the study of the binding and possible repercussions on the chemical determination, the electrolyte content of the sample in the punched hole of the microbiological test plate, losses of activity or synergistic effects of the serum-antibiotic combination during incubation of microbiological test plates after termination of the equilibrium dialysis. The determination of binding constants by means of a competitive fluorescence titration, the chemical analysis of equilibrium dialyses and their parallel assessment with the aid of the agar-diffusion plate test led to results which were not in agreement with each other. Turimycin which is very slightly soluble at pH = 7.4 and fairly soluble at pH = 5.0, is practically not bonded at the lower pH value of BSA and serum proteins (fluorescence titration of BSA: Kb approximately 20; equilibrium dialysis and chemical evaluation). The microbiological determination in serum on the basis of equilibrium dialyses yields higher values for the binding of turimycin.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Assay↗
PubMed1982

Solid phase antigen luminescent immunoassays (SPALT) for the determination of insulin, insulin antibodies and gentamicin levels in human serum.

We describe an interesting and novel alternative to conventional immunoassay techniques for the measurement of antigens and antibodies in body fluids. The label used for all assays is a pyruvate kinase-IgG conjugate of the relevant second (species-specific) antibody. All assays follow the same principle in which a solid phase antigen is used to adsorb unreacted first (substance-specific) antibody following a conventional antibody-antigen reaction in a liquid phase. After washing, the solid phase antigen-first antibody is allowed to react with the labelled second antibody. The solid phase is then washed and the pyruvate kinase bound to the solid phase is used to generate ATP which is measured kinetically in a luminometer. Assays are described for insulin, insulin antibodies and gentamicin to demonstrate both the versatility and sensitivity of this type of assay. The insulin assay had a lower detection limit of under 0.25 microU per tube and was comparable with the radioimmunoassay used for routine purposes both in sensitivity and reproducibility. The insulin antibody assay correlated well with the radiometric determination used routinely in the laboratory. The gentamicin assay correlated well with the routine commercial radioimmunoassay and also had comparable coefficients of variation. In all cases, the inter- and intra-assay variation was under 10% in the range of interest.

Animals↗
PubMed1982

Enzyme enhanced luminescence immunoassay for the determination of transferrin concentrations in serum.

An enzyme enhanced luminescence immunoassay has been developed using the determination of serum transferrin as a model. The assay has been compared with an established radioimmunoassay, the details of which have already been published (Wood, W. G. et al. (1980) Fresenius Z. Anal. Chem. 301, 120). After comparison, the luminescence immunoassay was introduced as the routine method for determining transferrin levels in human serum. The enzyme enhanced luminescence immunoassay uses a pyruvate kinase labelled transferrin as tracer, which, after the antibody-antigen reaction and subsequent bound-free separation, is used to generate adenosine triphosphate (ATP) from adenosine diphosphate(ADP) and phosphoenol pyruvate. The ATP is then monitored with a firefly luciferin-luciferase reagent, using a luminometer as detection system. The intra- and interassay coefficients of variation were under 10% and under 13% respectively in the range 0.6-4.5 g . liter-1. The stability of the lyophilised tracer was in excess of 5 months when stored at 4 degrees C, and the sensitivity of the assay lay under 0.1 micrograms per tube, although the detection limit of this type of assay system has not been fully explored.

Adenosine Triphosphate↗