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Biomedical subjects

M A Baumann

Publications and source records attributed to M A Baumann.

At least 19 recordsLinked to original sources
PubMed1992

Interleukin-5 is an autocrine growth factor for Epstein-Barr virus-transformed B lymphocytes.

Because of the recent finding that interleukin-5 (IL-5) is produced by Epstein-Barr virus-transformed B lymphocytes (EBV-B cells), we performed studies to ascertain whether EBV-B cells might use IL-5 by an autocrine mechanism. EBV-B cells known to be IL-5 producers were capable of responding to addition of exogenous IL-5 by dose-related augmented proliferation. The addition of a neutralizing anti-IL-5 antibody reduced these effects and also dose-dependently inhibited proliferation and reduced viability of unsupplemented EBV-B cells, having a maximum effect at about 120 hours. In contrast, no stimulatory effect of IL-5 was noted on Burkitt's lymphoma cell lines, nor were these lines growth-inhibited by anti-IL-5 antibody. With biotinylated IL-5, (b-IL-5) second labeling with streptavidin-FITC, and flow cytometric analysis, binding of IL-5 to EBV-B cells cultured in fresh medium was demonstrated and could be competed for by excess unlabeled IL-5, suggesting the presence of IL-5-specific binding sites. Binding of IL-5 was reduced on cells cultured for longer periods before study but could be restored by extensively washing cells before labeling them with b-IL-5, suggesting that surface binding sites had become occupied by endogenously produced IL-5. These findings support a role for IL-5 in autocrine support of EBV-B cell growth.

Antibodies↗
PubMed1992

Effects of interleukin-5 on acute myeloid leukemias.

Because of the known activity of interleukin-5 (IL-5) as a growth factor for human eosinophils, we performed studies to ascertain whether M4Eo acute leukemia cells might be capable of responding to IL-5. Surprisingly, short term incubation of freshly isolated M4Eo blasts with rhIL-5 induced differentiation of the cells to macrophages. To determine whether other variants of acute myelogenous leukemia (AML) might also be capable of responding to IL-5, we studied cells from four additional unselected cases and found that one responded to IL-5 by vigorous proliferation. Using biotinylated rhIL-5, second labelling with streptavidin-fluorescein isothiocyanate (FITC) and flow cytometric analysis, specific binding of IL-5 to both responsive leukemias was demonstrated, suggesting the presence of specific IL-5 receptors. Additional study will be needed to assess the frequency of IL-5 responsiveness in AML and to determine the relationship of these phenomena to the physiologic role of IL-5 in the regulation of hematopoiesis.

Cell Differentiation↗
PubMed1992

[A temperature rise in the dental pulp during the electrothermal removal of ceramic brackets].

The aim of the present in-vitro study was to evaluate the changes in pulp temperature associated with thermal debonding of ceramic brackets using the Ceramic Debonding Unit (Dentaurum). In addition, several forms of false usage were simulated. Instead of thermoelements, the non-contact infrared thermography device SST/THETA 1000 (Heimann) was employed for the dynamic measurement of pulp temperature. Successful debonding after a single activation resulted in a maximal temperature change of 3 degrees C. These in vitro results indicate that the Ceramic Debonding Unit--properly applied--is gentle on the pulp tissue. If debonding fails, the increase in temperature is higher. The influence of differing bracket base morphologies and various resins on electrothermal debonding are discussed.

Body Temperature↗
PubMed1992

[An in-vitro study of the interference of orthodontic banding and filling materials].

Discoloring and layers on bands and restorations during fixed orthodontic therapy are well known clinical phenomenon. Because of the complexity of etiological factors an in-vitro model was used in this study. Aim of the study was to examine the amounts and sort of metals which are dissolved. Therefore, respectively 25 normed MOD-cavities in Frasaco-teeth were filled with a non-gamma-2-amalgam (Amalcap plus, Vivadent) and condensed manually or mechanically. In addition, ten crowns of a high golden (Maingold SG, Heraeus) as well as a palladium basis alloy (Albabond A, Heraeus) were casted. Then they were banded with stainless steel bands (Dentaurum) and cemented with a glass ionomer cement (Ketac Cem, Espe). The probes were given into a 0.1 molar lactic acid for seven days at 37 degrees C. Using ICP (ion coupled plasma) analysis the corrosion solution was examined for elements. High levels of Zn- and Al-ion contents were found, which are components of the used cements. The filling materials themselves mainly set free small amounts of Ag, Sn or Cu. The steel band released Fe, Cr, Ni and Ti. The combination of filling material and band resulted in a higher release of most ions.

Corrosion↗
PubMed1992

A concept of restorative treatment during orthodontic therapy.

Orthodontic therapy with fixed appliances bears a high risk of plaque accumulation, resulting in demineralization and new carious lesions. Rather than treat incipient lesions in orthodontic patients, most general dental practitioners decide to await future developments. A new concept for comprehensive restorative and endodontic treatment is presented, and its orthodontic implications are discussed.

Dental Caries↗
PubMed1992

Protective gloves.

The worldwide emergence of acquired immune deficiency syndrome (AIDS) has led to the wide use and acceptance of gloves as a measure of protection against infection in dental practice. Problems caused by the frequent use of gloves are already known from experiences in the surgical sector and have taken on a new urgency: these include impermeability, the difficulties of disinfection, and adverse skin reactions. In addition, there are specific dental questions such as the interference of gloves with electrical sensitivity tests and also with the taking of impressions. This paper discusses topical aspects of glove use and possible solutions to current problems.

Equipment Design↗
PubMed1992

[Silicone molding compounds and latex gloves. The effect of latex gloves on addition and condensation silicones].

Inhibited setting of addition silicones has been observed using latex gloves in the dental office. Therefore four addition silicones as well as four condensation silicones were mixed with seven latex gloves with different properties (sterility, powder, accelerator, inner layer). The masses were mixed with bare hands as a control and--additionally--with powdered hands. Condensation silicones stayed unaffected when put together in exact amounts, while some addition silicones showed nearly complete inhibition. Mixing the condensation silicones under the conditions of daily practice--one spoon of body plus a distinct amount of catalyst-resulted in hardness differences compared to using the exact dose. Nevertheless the resulting impressions were of satisfying quality. The powder-component (Bio-sorb, Surgikos) leads to an accelerated setting. The general dental practitioner/dental hygienist have to consider these aspects while choosing gloves and silicone putties for taking impressions.

Dental Impression Materials↗
PubMed1991

Multiple isolated brain metastases from a Duke's B colon carcinoma.

Brain metastases from colorectal carcinomas are very uncommon and are almost uniformly seen in the setting of advanced, systemic disease. We describe a unique case of multiple, isolated brain metastases occurring from a Duke's B carcinoma of the sigmoid colon. Careful staging at two intervals at which clinical brain metastases were found did not disclose additional evidence of systemic disease. The cascade mechanism thought to be involved in the development of systemic metastases is reviewed, and a possible alternate route is suggested for direct access by tumor cells to the brain via Batson's vertebral plexus.

Adenocarcinoma↗
PubMed1991

A method for identifying a proposed carbohydrate-binding motif of proteins.

An examination of the binding sites of four carbohydrate binding proteins (Escherichia coli lactose repressor, E. coli arabinose-binding protein, yeast hexokinase A and Concanavalin A) revealed certain similarities of amino acid sequences and residues forming hydrogen bonds and hydrophobic interactions with the bound carbohydrate. These were: (i) Asx-Asx, hydrogen bonding to the pyranose ring oxygen and anomeric-OH group; (ii) Arg-X-X-X-(Ser/Thr), or the reverse sequence, with the Arg hydrogen bonding to the pyranose ring oxygen; (iii) Lys-(Ser/Thr)-X-X-Asp, or the reverse sequence and with interchange of the Lys-(Ser/Thr) positions, with hydrogen bonding of either or both the Lys and Asp residues to the -OH groups at carbons 2, 3, 4 or 6; (iv) a diaromatic sequence with possible hydrophobic interactions to the faces of the pyranose ring structure. An algorithm was devised to search the amino acid sequences of a large number of proteins, those known to bind carbohydrates as well as those without known carbohydrate-binding activities, for the four amino acid sequence criteria. The algorithm incorporated a weighted distance value (WDV) to assess the approximate distance between any two criteria, with the WDV being based on the predicted secondary structure of the protein amino acid sequence. When the algorithm using criteria 1 and 2 plus the WDV was applied to the sequences of 125 proteins, the method indicated the presence of the potential carbohydrate-binding site motif for 42% of proteins with known carbohydrate binding, only 8% of proteins were predicted as false positives, and the accuracy of the method was calculated to be 61.6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1991

Regional and systemic CD4 and CD8 subsets in bronchogenic carcinoma.

We studied lung and blood lymphocytes from 12 asymptomatic patients with peripheral bronchogenic carcinoma. Bronchoalveolar lavage was performed in the lung segment with tumor and a contralateral uninvolved lung segment and analyzed separately. After partial removal of macrophages by plastic adherence, cells were labeled with markers for CD4 and CD8 and analyzed by flow cytometric analysis. We found no significant difference in the percentages of mononuclear cells in either immune subset when comparing the lung containing tumor with the uninvolved lung. We did find, however, a depressed CD4/CD8 ratio in the peripheral blood. We conclude that a lung carcinoma does not change the local immunologic milieu of the lung parenchyma containing the carcinoma. It is not clear if the immunologic findings in the lungs and blood are due to the bronchogenic carcinoma, smoking, or the underlying chronic obstructive pulmonary disease.

Aged↗
PubMed1991

[Technique of posterior restorations with plastic composite materials].

The interest in tooth-colored restorations for posterior teeth has steadily grown in the last years. Several inlay-techniques using composites and ceramics are in competition with the direct filling-technique in with plastic compositemasses are applied. The way of filling directly with plastic composites is widely spread and the easiest one of the listed techniques. Therefore the momentary state of the art will be discussed.

Composite Resins↗
PubMed1991

[Conservation concerns in multiband treatment].

If (secondary) caries or amalgam fractures occur during fixed orthodontic treatment, the general dentist usually faces difficulties. Often temporary fillings are inadequate. Due to marginal leakage or break down they may jeopardize an orthodontic result. Step by step four cases of operative dentistry during fixed orthodontics are presented. A wait-and-see attitude or temporary measures for a longer period of time are definitely contraindicated.

Adolescent↗
PubMed1990

An immune complex selective affinity matrix utilizing a synthetic peptide.

A synthetic peptide possessing an amino acid sequence patterned on the globular head region of human complement component 1 subcomponent q (C1q) was tested for immunoglobulin binding. The peptide designated complementary binding peptide 2 (CBP2) was able to inhibit Staphylococcus aureus Protein A and human C1q from binding rabbit immunoglobulin at peptide concentrations for 50% inhibition of 1 and 10 microM, respectively. When attached to a solid-phase matrix in a column, CBP2 was able to bind immune complexes consisting of horseradish peroxidase plus rabbit antiperoxidase antibody or alkali-aggregated human immunoglobulins. A 1:4 mixture of immune complex to free immunoglobulin when passed over the CBP2 column demonstrated selective immune complex binding. Further controls established that CBP2 was in fact binding the immunoglobulin component of the immune complexes in a reversible fashion. The immune complex specificity of the column suggested a functional affinity was forming when CBP2 interacted with immune complexes. The possibility that the sequence of CBP2 is part of the immunoglobulin binding site of human C1q is discussed.

Amino Acid Sequence↗
PubMed1990

Epstein-Barr virus transformed B lymphocytes produce interleukin-5.

Interleukin-5 (IL-5) has previously been isolated only as a product of T lymphocytes. We have found that Epstein-Barr virus transformed B lymphocytes produce large amounts of IL-5 activity in culture supernatants, inducing proliferation of murine BCL1 cells, and supporting the selective growth of eosinophil colonies in semi-solid culture. Production of IL-5 messenger RNA by transformed B-cell lines was verified by Northern analysis using a 3.2-kilobase cloned DNA fragment containing the full-length human IL-5 gene, and immunoreactive IL-5 was detected in B-cell culture supernatants. These findings suggest a possible expanded role for the B cell in the induction of eosinophilia, and should serve as a focus for additional investigation into possible roles for IL-5 in human B-cell proliferation and differentiation.

B-Lymphocytes↗
PubMed1990

Modulation of spontaneous outgrowth of Epstein-Barr virus immortalized B-cell clones by granulocyte-macrophage colony-stimulating factor and interleukin-3.

Spontaneous outgrowth of immortalized Epstein-Barr virus (EBV) infected B-cell clones will occur from cultures of peripheral blood mononuclear cells (PBMNCs) of some persons with a history of EBV infection. We determined that outgrowth of such clones may be reproducibly modulated by supplementation of cultures with the hematopoietic growth factors GM-CSF and interleukin-3 (IL-3). Continuous supplementation of cultures with GM-CSF facilitates emergence of immortalized B-cell clones, whereas supplementation with IL-3 completely prevents their emergence. The effect of GM-CSF may be direct, at least in part, as the proliferation of pure clones of EBV-transformed B lymphocytes was augmented in response to GM-CSF. An indirect mechanism appears to be responsible for the inhibition of transformed B-cell outgrowth in response to IL-3, as IL-3 had no inhibitory effect on proliferation of pure transformed B-cell clones and IL-3-mediated inhibition could be eliminated by antibody neutralization of gamma-interferon (gamma-IFN) or tumor necrosis factor-alpha (TNF-alpha) early in culture. The mechanisms of these effects deserve further study and may have clinical relevance to use of hematopoietic growth factors for support of bone marrow (BM) function in immunocompromised patients.

B-Lymphocytes↗