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Biomedical subjects

W Bessler

Publications and source records attributed to W Bessler.

At least 37 records · Page 2Linked to original sources
PubMed1988

Activation of glomerular mesangial cells by gram-negative bacterial cell wall components.

The cell walls of gram-negative bacteria contain several biologically active components, including lipopolysaccharide (LPS), lipoprotein, and protein 1. The effects of these individual components and a synthetic analog of lipoprotein, TPP, on several activation parameters of glomerular mesangial cells (MC) were examined. Prostaglandin secretion, synthesis of the autogrowth factor, mesangial interleukin-1 (IL-1), and new synthesis of cellular proteins were assessed as markers of MC activation. All bacterial cell wall components evaluated were active in varying degrees as stimulants of prostaglandin secretion. In general, PGE was the predominant product. TPP and protein 1 also induced substantial secretion of thromboxane. Each cell-wall component was effective in stimulating mesangial IL-1 secretion. The activation of MC was associated with the enhanced synthesis of many cellular proteins in addition to IL-1. Stimulation by these bacterial components was dependent on the state of the mesangial cell cycle, because nonproliferating cells did not respond to these factors. Activation of MC by gram-negative bacterial cell wall components, with release of vasoactive prostaglandins and peptide mitogens, may be responsible for some of the glomerular hemodynamic alterations and cellular proliferative events associated with sepsis or chronic bacterial infection.

Animals↗
PubMed1987

Lipopeptides of the N-terminus of Escherichia coli lipoprotein: synthesis, mitogenicity and properties in monolayer experiments.

The N-terminal part of the lipoprotein from the outer membrane of Escherichia coli, tripalmitoyl-S-glyceryl-L-Cys-Ser and analogs with longer sequences, are polyclonal activators for B-lymphocytes. Triple-chain lipopeptides also constitute efficient low-molecular-weight carrier/adjuvant systems, which can be linked to antigens to yield immunogens for antibody production without further additives. This is the first report of monolayer experiments with chemically well defined, synthetic lipopeptide mitogens with the composition of the N-terminus of an important bacterial membrane protein. Various derivatives of the lipoprotein N-terminus were synthesized. These lipopeptides differed in the length of the peptide moiety, the number of fatty acid residues, and protective groups. In order to obtain the surface areas for the lipopeptides in isotherms and hysteresis isotherms, monolayer experiments with a computer-controlled film balance were performed. To get some information about the interaction of these compounds with typical membrane lipids mixed monolayers were formed from triple-chain lipopeptides with dipalmitoylphosphatidylcholine and cholesterol. A comparison of the mitogenic response of the compounds was made in an in vitro system with B-lymphocytes from Balb/c mice.

Animals↗
PubMed1987

Separation of plasma membrane domains of calf thymocytes by affinity chromatography on ouabain-Sepharose.

Highly purified plasma membranes of calf thymocytes were fractionated by means of affinity chromatography on ouabain-Sepharose. By the method used two subfractions were obtained, one eluting freely from the affinity gel (MF1oua) and a second specifically retained by matrix-bound ouabain (MF2oua), with a total recovery of 95 per cent. Fractionation required the binding of matrix-bound ouabain to its plasma membrane receptor, i.e. (Na+ + K+)-ATPase. Increasing the temperature and binding time did not significantly alter the fractionation of plasma membranes into the two subfractions. Both plasma membrane subfractions separated by ouabain-Sepharose were of plasma membrane origin, as revealed by the identical specific activities of several membrane bound enzymes, gamma-glutamyl transpeptidase, alkaline phosphatase and Mg2+-ATPase in unseparated plasma membranes and in both subfractions, and by the identical amounts of the cytoskeletal protein actin in unseparated plasma membranes and subfractions. The plasma membrane subfractions MF1oua and MF2oua showed different structural and functional properties. In SDS-polyacrylamide gel electrophoresis polypeptides of 170, 150, 110, 94, 39, and 30 kDa were several-fold enriched in the adherent fraction, MF2oua. The phospholipid fatty acid composition of the plasma membrane subfractions proved to be different, as well. MF2oua contained significantly higher amounts of saturated fatty acids as compared to MF1oua. The specific activities of (Na+ + K+)-ATPase, Ca2+-ATPase and lysolecithin acyltransferase were highly enriched in the adherent fraction MF2oua, as compared to MF1oua. The data suggest that by the means of affinity chromatography on ouabain-Sepharose plasma membrane domains of the lymphocyte plasma membrane can be isolated, most probably implicated in the initiation of lymphocyte activation.

Animals↗
PubMed1985

Segregation of reactivity to the mitogens lipopolysaccharide, lipoprotein and dextran sulfate in clones of the B cell lymphoma line WEHI 279.1.

The B cell lymphoma line WEHI 279.1 (surface IgM+, I-A+ and I-E+) was used as a model system to analyze functional reactivity of B lymphocytes to mitogens. Among the mitogens tested, lipopolysaccharide (LPS), lipoprotein (LP), and dextran sulfate (DxS) all induced a strong, dose-dependent growth inhibition of tumor cells. The analysis of independently derived clones, however, revealed that mitogen sensitivity could be lost in the absence of detectable alterations in the expression of those surface markers. Moreover, reactivity to LPS, LP and DxS segregated independently in these clones, suggesting distinct triggering mechanisms and functional receptors for these mitogens on the B cell membrane.

B-Lymphocytes↗
PubMed1985

Human B-cell differentiation induced by murein.

Like "true" polyclonal B-cell activators (PBA) for murine B cells, crude membrane preparations of Klebsiella pneumoniae (Klebs M) and some other enterobacteriaceae stimulate human B cells to mature into immunoglobulin (Ig) secreting cells without significant prior proliferation and in the absence of T cells. To investigate the biochemically defined membrane component with this unique PBA property, we studied lipoprotein and murein isolated from E. coli, since other components (e.g., a variety of lipopolysaccharide (LPS) fragments) failed to imitate Klebs M as a PBA. Mononuclear cells (MNC) and B cell-enriched cell populations from healthy blood donors were stimulated with various doses of lipoprotein and murein and, in comparison, Klebs M and pokeweed mitogen (PWM). Cell cultures exposed to either lipoprotein, murein, or Klebs M failed to incorporate [3H]thymidine significantly after 5 days in culture. In contrast, there was significant DNA synthesis (stimulation index greater than 3) when PWM was given to the same MNC population. All stimulants, with the exception of lipoprotein, induced B-cell differentiation in MNC cultures, as measured by an ELISA quantitating secreted Ig in the culture supernatants. In cultures with B cell-enriched cell populations, however, only Klebs M and murein were able to induce the production of significant amounts of IgM. Thus, the actual PBA moiety contained in the crude membrane fraction (Klebs M) appears to be associated with murein. It is important to note that murein induced considerably weaker Ig secretion than Klebs M did.

B-Lymphocytes↗
PubMed1983

Synthesis of the mitogenic S-[2,3-bis(palmitoyloxy)propyl]-N-palmitoylpentapeptide from Escherichia coli lipoprotein.

The N-terminal pentapeptide of the lipoprotein from the outer membrane of Escherichia coli was obtained by coupling S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N-palmitoyl-(R)-cysteine to O-tert-butylseryl-O-tert-butyl-seryl-asparaginyl-alanine tert-butyl ester followed by deprotection with trifluoroacetic acid. The tetrapeptide was built up from alanine tert-butyl ester with N-9-fluorenylmethyloxycarbonyl protected amino acids. S-[2,3-Bis(palmitoyloxy)propyl]-N-palmitoylcysteine was obtained from N,N'-dipalmitoylcystine di-tert-butyl ester via reduction to the thiol, and S-alkylation with racemic 3-bromo-1,2-propanediol followed by esterification with palmitic acid in the presence of dicyclohexylcarbodiimide/dimethylaminopyridine and deprotection with trifluoroacetic acid. The compounds were characterized unequivocally by 13C-NMR and mass spectra. The diastereomers of S-[2,3-bis(palmitoyloxy)propyl]-N-palmitoylcysteine tert-butyl ester with opposite configuration at the propyl-C-2 atom could be separated on a silica-gel column.

Escherichia coli↗
PubMed1982

Vertebral growth arrest lines after Cushing's syndrome. A case report.

An advanced case of Cushing's disease developing in a boy during adolescence is cured by bilateral adrenalectomy at the ages of 18 and 21 years. There is complete restitution of the previous osteoporosis. Due to appositional growth also the codfish deformity of the vertebral bodies shows an almost complete reversibility. The indented vertebral plates with their marginal condensation remain visible permanently as growth arrest lines. The long tubular bones of the extremities were not involved by Cushing's disease and showed normal development without appearance of growth arrest lines.

Adolescent↗
PubMed1979

[Dedifferentiation of chrondrosarcomas (author's transl)].

The clinical course and the results of radiographic and histological investigations in three patients with dedifferentiated chondrosarcoma are presented. The tumors were characterized by chondrosarcomatous tumor sections of low grade malignancy adjacent to fibrosarcomatous tissue sections. One to two and one-half year after the onset of the first clinical symptoms pulmonary metastases appeared and in one case a subcutaneous mass presented, which had the histological appearance of a fibrosarcoma. Differentiation of a chondrosarcoma customarily has an adverse effect on the prognosis with both the early appearance of metastases and a rapidly fatal clinical course. Cartilagenous tumors of the axial skeleton and the long bones must be extirpated surgically in an early and radical fashion, particularly if there are radiographic signs of proliferation.

Adult↗
PubMed1979

[Radiological and scintigraphic evaluation of hip prostheses (author's transl)].

The radiological findings following the introduction of hip prostheses are often equivocal. Additional bone scintigrams often provide important information for the evaluation of the prostheses. 1. An unstable hip prosthesis is characterised by abnormal uptake in bone, due to static and mechanical stress. 2. A positive scintigram does not necessarily indicate instability of the prosthesis. Increased uptake may also be due to inflammatory bone changes, healing, bone replacement, abnormal local stresses or soft tissue calcification. 3. In evaluating the scintigram one must take account not only of the intensity of isotope uptake, but also its distribution and exact localisation. 4. It is essential to compare the scintigram with the radiograph. Radiological features of possible instability become diagnostic if they correspond to appropriate increased radioactivity. If the latter is absent, the of instability remains doubtful. 5. In some cases early loosening of the stem of the prosthesis can be diagnosed while the radiograph is still negative. Increased radioactivity in the acetabulum is frequently seen in the presence of a stable acetabular prosthesis and must be interpreted with caution as a sign of loosening of the prosthesis.

Aged↗
PubMed1977

[Transvenous removal of a catheter which has embolised to the heart (author's transl)].

The removal of intravenous catheters that embolized into the vena cava superior and the right atrium, is described. This is done with a "Dormia basket", in conjunction with a controllable Medi-Tech-Selection-Catheter. This set is especially suited for the removal of intracardial foreign bodies. The extraction of a catheter is a relatively expedient procedure without undue discomfort for the patient.

Aged↗
PubMed1977

Induction of lymphocyte proliferation and membrane changes by lipopeptide derivatives of the lipoprotein from the outer membrane of Escherichia coli.

Lipoprotein from the outer membrane of E. coli, a potent novel mitogen, was digested by pronase treatment resulting in lipopeptide fragments containing 2-5 amino acids bound to diacylglyceryl-N-acylcysteinthioether. The lipopeptides were characterized by amino acid analysis and gas chromatography and were checked for mitogenicity. We found that all lipopeptide fragments were able to stimulate the uptake of 3H-uridine into RNA and 3H-thymidine into DNA in mouse spleen cells of several strains. The response of splenocytes of congenitally athymic mice was comparable to that of normal animals. A weak stimulation of DNA synthesis was also observed in thymocytes. The mitogenicity of the products was abolished by mild alkali hydrolysis which removes the ester-bound fatty acids. We conclude that the N-terminal lipopeptide region of lipoprotein is responsible for the mitogenic activity of the molecule. Lipopeptide as well as lipoprotein were found to cause early membrane changes in lymphocyte plasma membranes. After 4 hours we found an increased incorporation of 14C-oleate and 14C-acetate into lecithin. The membrane changes observed are similar to those brought about by mitogenic lectins, which suggests a similar mechanism for the induction of lymphocyte activation for both types of mitogens.

Amino Acids↗