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G Dietrich

Publications and source records attributed to G Dietrich.

At least 37 records · Page 2Linked to original sources
PubMed2000

Bacterial systems for the delivery of eukaryotic antigen expression vectors.

Attenuated bacterial strains allow the administration of recombinant vaccines via the mucosal surfaces. Whereas attenuated bacteria are generally engineered to express heterologous antigens, a novel approach employs intracellular bacteria for the delivery of eukaryotic antigen expression vectors (so-called DNA vaccines). This strategy allows a direct delivery of DNA to professional antigen-presenting cells (APC), such as macrophages and dendritic cells (DC), through bacterial infection. The bacteria used for DNA vaccine delivery either enter the host cell cytosol after phagocytosis by the APC, for example, Shigella and Listeria, or they remain in the phagosomal compartment, such as Salmonella. Both intracellular localizations of the bacterial carriers seem to be suitable for successful delivery of DNA vaccine vectors.

Antigen-Presenting Cells↗
PubMed2000

Novel bacterial systems for the delivery of recombinant protein or DNA.

On the basis of attenuated intracellular bacteria, we have developed two delivery systems for either heterologous proteins or DNA vaccine vectors. The first system utilizes attenuated strains of Gram-negative bacteria which are engineered to secrete heterologous antigens via the alpha-hemolysin secretion system of Escherichia coli. The second system is based on attenuated suicide strains of Listeria monocytogenes, which are used for the direct delivery of eukaryotic antigen expression vectors into professional antigen presenting cells (APC) like macrophages in vitro as well as in vivo.

Animals↗
PubMed2000

Current status and future perspectives of DNA vaccine delivery by attenuated intracellular bacteria.

Vaccination by intradermal or intramuscular injection of antigen-encoding plasmid-DNA elicits strong cellular and humoral immune responses. Professional antigen presenting cells (APC) seem to induce these responses, making it, therefore, desirable to deliver the plasmid molecules directly to these cells. The exploitation of attenuated intracellular bacteria as DNA delivery vehicles makes the direct targeting of DNA vaccine vectors to professional APC feasible.

Animals↗
PubMed1999

Effects of kinematics constraints on hand trajectory during whole-body lifting tasks.

Trajectories of the hands and whole-body center of mass were studied during whole-body lifting tasks. The movements of different parts of the body were monitored with the ELITE system. Subjects were instructed to lift to shoulder height an object placed at one of two distances (5-45 cm) before them on the floor. The lifts were performed both with and without kinematics constraints (i.e. to produce a straight hand trajectory while lifting, and to lift without any instructions, respectively). Hand trajectories were roughly straight when performed under the constrained condition, but curved when performed without instruction. Hand velocity curves showed bell-shaped profiles. In both groups, body centers of mass (whole-body, upper and lower part) were calculated and their trajectories showed invariant sagittal displacements. These results support the idea that movement contributes to postural control and, reciprocally, that whole-body center of mass is a robust and controlled variable which plays an important role in hand trajectory formation.

Adult↗
PubMed1999

Morphine-like activity of natural human IgG autoantibodies is because of binding to the first and third extracellular loops of the mu-opioid receptor.

We have previously demonstrated that randomly selected healthy individuals express anti-human mu-opioid receptor antibodies which behave as agonist in vitro. In this study, we show that the activity of these antibodies was not affected by the deletion of the amino-terminal region of the receptor. Using agarose-bound peptide columns, we affinity-purified IgG specifically directed toward each extracellular loop. Whatever its specificity, each anti-human mu-opioid receptor (hMOR) extracellular loop peptide IgG preparation was unable, when examined individually, to reduce adenylate cyclase activity. Activation of the hMOR was, however, achieved by the simultaneous binding of IgG to the first and third extracellular loops of the receptor. Our results suggest that the simultaneous binding of IgG antibodies to these two loops mimics morphine-induced receptor activation by triggering a coordinated shift of the third and sixth transmembrane helices.

Amino Acid Sequence↗
PubMed1999

Isolation and characterization of natural human IgG with a morphine-like activity.

Although naturally occurring antibodies have been associated with numerous biological activities, their functional relevance is still a matter of debate. The presence of natural autoantibodies towards immune-related molecules such as cytokines and antibodies suggests a physiological immunomodulatory role. The neuroendocrine opioid system participates in the immune homeostasis. We report here the presence of antibodies with an agonist-like activity towards the human mu-type opioid receptor within a normal human IgG pool. Starting from an IgG pool, autoantibodies were affinity purified using Chinese hamster ovary cells expressing the human mu-opioid receptor. Their specificity was assessed by cytofluorometry and pharmacological analyses. The potency of these antibodies to recognize the mu-opioid receptor was similar to mu-opioid selective agonists. Furthermore, the functional opioid-like activity of the anti-opioid receptor IgG was demonstrated by their ability to inhibit adenylate cyclase activity by a Gi/o-protein-mediated mechanism as indicated by abrogation of the effect by either opioid antagonist or pertussis toxin. Five IgG pools, each from four unrelated healthy blood donors, and single IgG preparations from six other donors were prepared. Antibodies directed against the mu-opioid receptor were found in all IgG samples.

Adenylyl Cyclases↗
PubMed1999

Introduction of protein or DNA delivered via recombinant Salmonella typhimurium into the major histocompatibility complex class I presentation pathway of macrophages.

Recombinant (r) Salmonella typhimurium aroA strains which display the hen egg ovalbumin OVA(257-264) peptide SIINFEKL in secreted form were constructed. In addition, attenuated rS. typhimurium pcDNA-OVA constructs harbouring a eukaryotic expression plasmid encoding complete OVA were used to introduce the immunodominant OVA(257-264) epitope into the major histocompatibility complex (MHC) class I presentation pathway. Both modes of antigen delivery (DNA and protein) by Salmonella vaccine carriers stimulated OVA(257-264)-specific CD8 T-cell hybridomas. An in vitro infection system was established that allowed both rSalmonella carrier devices to facilitate MHC class I delivery of OVA(257-264) by coexpression of listeriolysin (Hly) or by coinfection with rS. typhimurium Hlys (Hess J., Gentschev I., Miko D., Welzel M., Ladel C., Goebel W., Kaufmann S.H.E., Proc. Natl. Acad. Sci. USA 93 (1996) 1458-1463). Coexpression of Hly and coinfection with rS. typhimurium Hlys slightly improved MHC class I processing of OVA. Our data provide further evidence for the feasibility of attenuated, Hly-expressing rS. typhimurium carriers secreting heterologous antigens or harbouring heterologous DNA as effective vaccines for stimulating CD8 T cells in addition to CD4 T cells.

Amino Acid Sequence↗
PubMed1998

[Anal gland carcinoma with osteoblastic metastases].

HISTORY AND CLINICALLY FINDINGS: A 52-year-old woman was admitted because of anal pain of 6 weeks duration. Physical examination was unremarkable except for a cherry-sized swelling, painful to pressure, on rectal examination. As the erythrocyte sedimentation rate and C-reactive protein were increased (69/115 and 12.1 mg/dl, respectively) and abscess was diagnosed. Carcinoembryonic antigen was within normal limits. INVESTIGATIONS: At rectoscopy a fluctuating abscess-linked swelling was found at 3 cm and a submucous tumour at 5 cm from the anus. TREATMENT AND COURSE: The abscess was cut open and at the level of the dentate line a submucous adenocarcinoma about 3 cm in diameter was resected. A small residual tumour was removed by abdomino-perineal rectal extirpation. As histologically it was an adenocarcinoma not of colorectal type, without relationship to rectal mucosa but in close contact to the anal glands, and the further course did not indicate a metastasis from another primary tumour, the diagnosis of anal gland adenocarcinoma was established. A local recurrency was resected 6 months later, followed by combined radio- and chemotherapy. A diffuse osteoblastic metastasis was discovered later and the patient died 21 months after diagnosis. CONCLUSION: An osteoblastic metastasis from an anal gland carcinoma, as occurred in this case, has not been previously reported.

Adenocarcinoma↗
PubMed1998

Non-immunoglobulin serum proteins prevent the binding of IgG from normal rats and from rats with Th2-mediated autoimmune glomerulonephritis to various autoantigens including glomerular antigens.

It is now well established in normal humans and mice that purification of IgG from serum unmasks their autoantibody activity. Mercuric chloride (HgCl2) induces in Brown-Norway (BN) rats a Th2-dependent polyclonal B cell activation, a huge increase in serum IgE and IgG1 concentrations, the production of numerous autoantibodies and an autoantibody-mediated glomerulonephritis. In the present study we have compared the IgG autoantibody activity in the serum and in the purified IgG fraction from normal and HgCl2-injected BN rats. IgG autoantibodies were found to be masked in normal serum by non-immunoglobulin (nonIg) serum proteins and, provided these IgG did not encounter normal serum proteins, they could bind to glomerular antigens as assessed by immunofluorescence in a unilateral perfused kidney model. As a consequence of HgCl2-induced polyclonal activation of B cells, IgG autoantibodies were no longer complexed to non-Ig serum proteins, they were easily detected in the serum and could therefore reach their glomerular target. However, these autoantibodies could still be blocked by normal non-Ig serum proteins not only in vitro but also in a unilateral perfused kidney model so that their binding to glomerular antigens could be prevented. These findings indicate that the ratio between autoantibody level and the amount of non-Ig serum proteins may be crucial in autoantibody-mediated autoimmune diseases.

Animals↗
PubMed1998

[Risk factors and frequency of adverse effects after autologous blood donation].

OBJECTIVE: Autologous blood donation before elective surgery decreases the perioperative risk although donation itself can cause adverse effects. Are there specific donor characteristics, which influence the frequency and severity of adverse effects? METHODS: We investigated in a prospective study 3603 autologous blood donations including registration of patient's age, gender, height, weight, medical record and risk-score by Böcker. The adverse effects were divided into severity groups (SG). The investigation took place in a Department of Anaesthesiology and Intensive Care Medicine in an university hospital. 1041 patients with preoperative autologous blood donation were investigated between January 1995 and April 1997. RESULTS: 7.4% of patients had adverse effects. Hypotension and bradycardia were the most frequent adverse effects. 4.3% of the adverse effects were graded as minimal (SG 1), 2.4% as mild (SG 2) and 0.7% as moderate (SG 3). The rate was higher in young donors (< 25 years). For all other donor characteristics including older age, cardiac or pulmonary diseases and high risk-score no higher donation risk was observed. CONCLUSIONS: Adverse effects during and after autologous blood donation are rare. Predictor for reaction seems to be young age (< 25 years). Referring to donor's characteristics and predonation risk factors it is hardly possible to predict adverse effects. Thus, all autologous blood donors require adequate monitoring by a physician. Under these circumstances the autologous blood donation is a safe procedure even in patients with severe risk factors.

Adolescent↗
PubMed1998

Delivery of antigen-encoding plasmid DNA into the cytosol of macrophages by attenuated suicide Listeria monocytogenes.

Eukaryotic expression vectors can be delivered to macrophages using attenuated self-destructing Listeria monocytogenes. L. monocytogenes cells are preferentially lysed in the host cell macrophage cytosol by the production of a PactA-dependent Listeria-specific phage lysin. Efficient expression of the cloned reporter genes by the macrophages and subsequent antigen presentation were achieved after the delivery of eukaryotic expression vectors by the attenuated suicide L. monocytogenes strain. After delivery by L. monocytogenes plasmid DNAs were found to integrate into the macrophage cell's genome at a frequency of about 10(-7).

Animals↗
PubMed1998

Implication of the first and third extracellular loops of the mu-opioid receptor in the formation of the ligand binding site: a study using chimeric mu-opioid/angiotensin receptors.

Recent studies on chimeric mu/delta-, mu/kappa- and delta/kappa-opioid receptors have suggested that extracellular loops of the receptors were involved in the discriminatory binding of selective ligands by controlling their entry into the transmembrane binding site. Since homochimeric opioid receptors are mostly informative in terms of selectivity, the role of extracellular loops was examined here by studying heterochimeric mu receptors where the totality or parts of extracellular loops were replaced by the corresponding regions of the receptor for angiotensin II. Chimeric mu receptors with extracellular loop EL1 or EL3 originating from the angiotensin receptor had 100-fold decreased affinities for opioids; the length of the first extracellular loop, which is one residue longer in angiotensin than mu receptors, was shown to be responsible for this situation. Substitution of the mu receptor second extracellular loop by that of the angiotensin receptor diminished by approximately 10-fold the affinities for opioids. Since all chimeras had altered affinities for selective and nonselective ligands, we propose that extracellular domains of the mu receptor, particularly the first and third loops, constrain the relative positioning of the connected transmembrane domains where selective as well as nonselective contact points form the opioid binding site.

Amino Acid Sequence↗
PubMed1997

Identification in the mu-opioid receptor of cysteine residues responsible for inactivation of ligand binding by thiol alkylating and reducing agents.

Inactivation by thiol reducing and alkylating agents of ligand binding to the human mu-opioid receptor was examined. Dithiothreitol reduced the number of [3H]diprenorphine binding sites. Replacement by seryl residues of either C142 or C219 in extracellular loops 1 and 2 of the mu receptor resulted in a complete loss of opioid binding. A disulfide bound linking C142 to C219 may thus be essential to maintain a functional conformation of the receptor. We also demonstrated that inactivation of ligand binding upon alkylation by N-ethylmaleimide occurred at two sites. Alteration of the more sensitive (IC50 = 20 microM) did not modify antagonists binding but decreased agonist affinity almost 10-fold. Modification of the less reactive site (IC50 = 2 mM) decreased the number of both agonist and antagonist binding sites. The alkylation site of higher sensitivity to N-ethylmaleimide was shown by mutagenesis experiments to be constituted of both C81 and C332 in transmembrane domains 1 and 7 of the mu-opioid receptor.

Alkylating Agents↗
PubMed1997

[Perfusion changes in hemodilution. The effect of extensive isovolemic hemodilution with gelatin and hydroxyethylstarch solutions on cerebral blood flow velocity and cutaneous microcirculation in humans].

OBJECTIVE: Quantifying the influence of extreme isovolemic hemodilution (NH) with different colloids on cerebral blood flow velocities (transcranial Doppler sonography) and cutaneous microcirculatory blood flow (laser Doppler flowmetry) in healthy, non-premedicated volunteers was the aim of this study. METHODS: In seven volunteers (randomized cross-over design) 20 ml/kg blood was withdrawn within 30 min and simultaneously replaced with 6% hydroxyethyl starch (200,000/0.5, HES) or 3% gelatin (GEL). Thirty minutes later, the autologous blood was retransfused (RT) within 30 min. Due to a severe allergic reaction to gelatin in one volunteer, only 6 GEL-NH were evaluated. Recorded parameters were: mean blood flow velocities (Vm-MCA) as well as the pulsatility index (PI) and the resistance index (RI) over the middle cerebral artery. In addition laser Doppler flux (FLUX), cell velocity (SPEED), mean arterial pressure (MAP), heart rate (HR), hemoglobin (Hb) and hematocrit (Hc) were monitored. RESULTS: NH resulted in a withdrawal volume of 1498 +/- 85 ml (HES) and 1493 +/- 95 ml (GEL), (mean +/- SD) and induced a decrease in hemoglobin from 40.9 to 29.0% (HES) and from 39.8 to 30.0% (GEL). RT increased Hc to 34.2% (HES) and 34.5% (GEL). MAP and HR showed no significant alterations in both groups. Following NH, Vm-MCA rose almost the same way in either case (26% HES), 21% (GEL), but decreased continuously again during RT. After completing RT, only in the HES group Vm-MCA still remained higher than baseline values (14% HES, only 3% GEL). Similar inverse regression lines were found for the two groups between Hc and Vm-MCA: [Vm-MCAHES (cm/s) = -1.27 x Hc + 110.9; r = 0.98, P < 0.001 and Vm-MCAGEL (cm/s) = -1.32 x Hc + 110.9; r = 0.91, P < 0.001]. Furthermore, as a result of NH, FLUX and SPEED increased about 61% and 38% in the HES group and remained on higher values in comparison with starting positions (21% FLUX, 13% SPEED). However, the results in the GEL group were of a different kind: FLUX and SPEED increased stupendously to 291% and 114% combined with NH, but both were reduced by RT on a large scale (39 and 27% below baseline values). Whereas RI showed no group differences, there was a remarkable drop in PI during RT (17% HES, 12% GEL). CONCLUSION: The two plasma expanders studied show a close inverse correlation between the alterations of blood flow velocities in the middle cerebral artery and systemic hemoglobin and hematocrit values. In both groups the change in blood flow velocities is comparable. For the first time the results of relative changes in blood flow velocities following hemodilution and retransfusion in healthy volunteers are described that correspond closely by relative cerebral blood flow alterations found in animal studies as well. Moreover, a non-linear correlation of cutaneous microcirculation was shown by means of HES, but also by GEL. Obviously, there was the GEL group to be responsible for pronounced differences in cutaneous circulation.

Adult↗
PubMed1997

Protection against murine listeriosis by an attenuated recombinant Salmonella typhimurium vaccine strain that secretes the naturally somatic antigen superoxide dismutase.

A recombinant (r)-Salmonella typhimurium aroA vaccine strain was constructed which secretes the naturally somatic protein of Listeria monocytogenes, superoxide dismutase (SOD), by the HlyB/HlyD/TolC export machinery. Vaccine efficacy of the SOD-bearing carrier strain was compared with that of the p60-secreting construct, S. typhimurium p60s (J. Hess, I. Gentschev, D. Miko, M. Welzel, C. Ladel, W. Goebel, and S. H. E. Kaufmann, Proc. Natl. Acad. Sci. USA 93:1458-1463, 1996). Vaccination of mice with both constructs induced protection against a lethal challenge with the intracellular pathogen, L. monocytogenes. While the somatic listerial antigen, SOD, is immunologically uncharacterized, the naturally secreted protein of L. monocytogenes, p60, is known to be highly immunogenic. Our data emphasize the high vaccine potential of r-Salmonella constructs secreting antigens of somatic or secreted origin. Moreover, they suggest that the HlyB/HlyD/TolC-based antigen delivery system with attenuated Salmonella spp. as the carrier is capable of potentiating the immune response against foreign proteins independent from their immunogenicity in and display by the natural host.

Animals↗