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Biomedical subjects

H Baumgarten

Publications and source records attributed to H Baumgarten.

At least 19 recordsLinked to original sources
PubMed2005

Charge-transfer-type fluorescence of 4-(1H-pyrrol-1-yl)benzonitrile (PBN) and N-phenylpyrrole (PP) in cryogenic matrixes: evidence for direct excitation of the CT band.

The fluorescence spectrum of PBN in a neat argon matrix is excitation-wavelength-dependent: at short excitation wavelengths, it consists of dual emission assigned to a charge-transfer (CT) state and a much weaker band assigned to the locally excited (LE) state. The CT emission is broad and almost completely devoid of vibrational structure, whereas the LE band is characterized by vibrationally resolved emission. At long excitation wavelengths, only CT emission is observed, indicating that the CT state is populated directly by light absorption and not via the LE state. Comparison with jet-cooled spectra of the bare molecule allows the unambiguous assignment of the LE spectrum and the location of the 0,0 band. The matrix LE emission spectrum is blue-shifted with respect to that of the gas phase, showing that the dipole moment of the LE state is smaller than that of the ground state. The fluorescence spectrum of PBN in an argon matrix does not change appreciably when acetonitrile (AN) is added to the matrix, in contrast to the case of N-phenylpyrrol (PP) (Schweke, D.; Haas, Y. J. Phys. Chem. A 2003, 107, 9554), for which addition of AN results in the appearance of two well separated emission bands. The different photophysical behaviors of PP and PBN in an argon matrix (and in supersonic jets) are analyzed by a simple model that considers the restriction of large-amplitude motions in the matrix. The implications of these low-temperature studies for understanding the properties of these systems in liquid solution are discussed.

Journal Article↗
PubMed2001

The management of gingival and esthetic problems: a clinical case.

The coordinated management of gingival and esthetic problems is important in dentistry. In addition, the most difficult variable to control in the treatment of anterior esthetics is the soft tissue. This article discusses the relationship between the surrounding soft tissue and the emerging crown form. The authors introduce a soft-tissue index model technique that will help the technician in fabricating the final crown with a form similar to the provisional. In this case report, provisional crowns are fabricated with enough tissue support to provide for an optimal crown-gingival interface. The present case demonstrates how to manage the gingival margin in the provisional stage and how to transfer the provisional and soft tissue to the laboratory model.

Adult↗
PubMed1996

Outcome failures of endosseous implants from a clinical training center.

In an effort to provide realistic clinical information from a "real-world" environment, the present retrospective study was undertaken to assess outcome failures after implant placement in a dental school clinical training center. A database was kept of the clinical information and was analyzed according to established parameters for implant outcomes. The demographics showed that over a period of 6 years, 80 different operators with a wide range of clinical experience had inserted 1,263 implants in a diverse patient pool of 380 individuals. Analysis of the outcomes showed a cumulative survival rate of 91.3%. The time of explantation, the type, size, and location of implants lost, and failure rates in smoking patients were also analyzed. The results indicated that the use of implants by operators with different levels of experience did not affect favorable outcomes.

Adult↗
PubMed1990

Quantitation of components of the alternative pathway of complement (APC) by enzyme-linked immunosorbent assays.

Sensitive enzyme-linked immunosorbent assays (ELISA) using monoclonal antibodies have been developed to specifically detect components of the alternative pathway of complement in human blood plasma. Normal values of the factor B split products Ba (1.01 +/- 0.30 micrograms/ml, mean +/- SD), Bb (0.65 +/- 0.23 micrograms/ml), of the C3-fragments C3b/iC3b/C3dg (17.9 +/- 5.7 micrograms/ml), native factor B (238 +/- 48 micrograms/ml), factor D (1.05 +/- 0.27 micrograms/ml), and factor H (702 +/- 292 micrograms/ml) were determined in the EDTA-plasma of healthy probands (n = 55). The simultaneous quantitation of the main cleavage products and of control proteins in the plasma samples permits precise analysis of the activation of the alternative pathway of complement in various disease states. In addition, we describe a method for the specific depletion of factor B prior to fragment-specific assays utilizing monoclonal antibodies conjugated to paramagnetic beads. The latter should permit the quantitation of other complement split products.

Animals↗
PubMed1990

Determination of the epitope specificities of monoclonal antibodies using unprocessed supernatants of hybridoma cultures.

A double monoclonal antibody (mAb) ELISA has been developed to determine the epitope specificities of murine monoclonal (mAbs). It permits the mAbs which bind to the same or adjacent epitopes to be distinguished from those which bind to separate epitopes on soluble monomeric proteins. The assay is designed for the early evaluation of mAbs in hybridoma culture supernatants when purified or labeled mAbs are not available. It does not rely on chemical or enzymatic fragmentation of the antigen and does not generate results which may be due to differences in the affinities of the mAbs. Moreover the characteristic multiple binding of polyclonal antibodies to the same epitope is also avoided. A further advantage is the accessibility of epitopes on a given antigen since the antigen is presented by a solid-phase mAb, in contrast to assays in which the antigen itself is adsorbed onto the solid phase. The test was evaluated using culture supernatants from hybridomas which produced mAbs against the complement proteins C3a, C6 or C7.

Animals↗
PubMed1987

Determination of the T3-3A1 antigen in PHA-induced human T-cells by standardized cell-ELISA.

The treatment of mononuclear leukocytes (MNL) with lectins induces marked changes in the cell's morphology, physiology and the composition of the cell surface. We used an immunoassay to monitor the PHA-induced expression of the T-lymphocyte-specific antigen T3-3A1 in fixed MNL with a monoclonal antibody (MoAb) specific for this antigen. This assay permits the detection and quantitation of the T3-3A1 antigen in a few thousand cells without the use of a FACS. The test was calibrated with isolated plasma membranes and, combined with a total protein determination, the relative content of T3-3A1 antigen in each sample could be calculated. Maximal T3-3A1 synthesis required a 10-fold lower concentration of PHA than was necessary for optimal DNA synthesis. The test may be used to screen for PHA stimulation.

Antibodies, Monoclonal↗
PubMed1986

A cell ELISA for the quantitation of leukocyte antigens. Requirements for calibration.

A cell ELISA for human leukocytes has been established and standardized. The assay was based on the use of air-dried and methanol-fixed cells which were attached to microplate wells. Cellular antigens were measured through the subsequent binding of monoclonal antibody (MoAb), biotinylated sheep Ig against mouse IgG and streptavidin-peroxidase conjugate. The test was standardized by measuring both the specific antigen and the amount of cellular protein in each single sample and was calibrated either with intact cells or isolated plasma membranes prepared from the cells under study. The detection of the pan T-lymphocyte-specific 3A1 antigen (CD7, P40) in fewer than 5000 cells or less than 50 ng membrane protein was possible.

Antibodies, Monoclonal↗
PubMed1985

A simple microplate assay for the determination of cellular protein.

In assays of leukocyte function it is desirable to correlate a specific measurement, e.g., the release of enzymes, the production of metabolites or the secretion of cytokines with the amount of cellular material. Many authors use either the protein or the DNA content of the cells as a reference. Specific measurements of cellular activity are often expressed as a ratio of activity/protein or activity/DNA. This communication describes a dye-binding assay which allows the determination of total protein of the same cell sample which was first used for the quantitation of a specific cellular function. The microplate assay described is an adaptation of the Coomassie blue dye-binding assay without the need of a separate step to lyse the cells. The test is useful for both adherent and non-adherent cells and has a detection limit of less than 500 ng BSA or 5000 leukocytes.

Cell Line↗
PubMed1984

A colorimetric assay for the assessment of cytotoxicity of yeasts.

A colorimetric assay for the quantitation of microbial cytotoxicity has been developed using cells from a monocyte-like human cell line (U937), epithelial cells (Hela), and fibroblast-like cells (Vero) as targets. The fraction of surviving cells was determined by their content of the dye neutral red which is retained only by live cells and can be quantitated photometrically after controlled lysis. The neutral red retention assay was at least as sensitive as the 51Cr-release assay; it was considerably less laborious, faster, and avoided handling of radioactivity. Among the different Candida species tested, the highest cytotoxicity was associated with C. albicans and C. tropicalis; a lower degree of cytotoxicity was exhibited by C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. pseudotropicalis. Among the strains of a given fungal species cytotoxicity varied by up to 40%.

Animals↗
PubMed1984

Large surface proteins of hepatitis B virus containing the pre-s sequence.

The sequence of hepatitis B virus DNA contains an open reading frame which codes for a not-yet-identified protein of at least 389 amino acids. Only the products starting at the third (GP33/GP36) or the fourth (P24/GP27) initiation signal have been characterized as components of the viral surface antigen. We found a larger protein, P39, and its glycosylated form, GP42, in hepatitis B virus particles and viral surface antigen filaments. Immunological cross-reactions showed that P39/GP42 is partially homologous to P24/GP27 and GP33/GP36. The unique portion of its sequence bound monoclonal antibodies which had been induced by immunization with hepatitis B virus particles. Proteolytic cleavage patterns and subtype-specific size differences suggested that the sequence of P39 starts with the first initiation signal of the open reading frame. Its amino-terminal part (pre-s coded) is exposed at the viral surface and, probably, is highly immunogenic. A model is presented of how the open reading frame for the viral envelope leads to defined amounts of three different proteins.

Antibodies, Monoclonal↗
PubMed1980

Seroepidemiologic investigations of hepatitis in the tropics. A study on volunteers of the German volunteer service.

Sera from 349 volunteers of the German Volunteer service (GVS), who had lived in tropical or subtropical countries for about two years were tested for Hepatitis B surface antigen two years were tested for Hepatitis B surface antigen (HBS-antigen), antibody to Hepatitis B surface antigen (anti--HBS), and antibody to Hepatitis A antigen (anti-HA) by radioimmunoassay. The findings were compared with those from a control group whose sex, age and occupational status corresponded with the volunteer group. The incidence of HBS-antigen was equal in both groups (1%). Anti-HA was found in 34% and anti-HBS in 19% of the volunteers but only in 26% and 7%, respectively, of the members of the control group. The greatest occurence of anti-HA was found among volunteers of the health service (46%) and technical service (35%) and of anti-HBS among the health service (29%), economic service (26%) and agricultural service (21%). Returned volunteers from West Africa showed a higher frequency (anti-HA 38%, anti-HBS 30%) than those from other countries (anti-HA 30%, anti-HBS 17%). The increased frequency of hepatitis corresponded with an increase in the morbidity rate from 25.5/10 000/year prior to service to 244/10 000/year during the service.

Adult↗