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Biomedical subjects

C Ammann

Publications and source records attributed to C Ammann.

6 recordsLinked to original sources
PubMed2006

Targeting human immunodeficiency virus type 1 with antibodies derived from patients with connective tissue disease.

During the budding process, human immunodeficiency virus (HIV) acquires several cellular proteins from the host. Thus, antibodies against self antigens found in sera patients with autoimmune disorders may cross react with host-derived or the HIV-specific proteins gp120 and gp41 on the viral envelope and probably neutralize HIV infection. To verify this hypothesis, 88 sera from HIV negative patients suffering from systemic lupus erythematosus (SLE) and other autoimmune disorders were analysed for cross reacting antibodies against HIV-1 by Western blot and FACS analysis indicating that antibodies cross-react with epitopes expressed on HIV infected or non-infected cells. Virus capture assays revealed that HIV-1(IIIB) was directly recognized by 60% of sera from patients with autoimmune disorders. Sera were also tested in HIV neutralization assays with stimulated T cells. Reduction of the viral load by patient sera correlated with their reactivity in Western blot analysis. Complement further enhanced the reduction of viral titres, although no complement-mediated lysis was observed. These data suggest a possible protective role of auto-antibodies against HIV infection in lupus patients.

Adolescent↗
PubMed2003

Contributions of anthropogenic and natural forcing to recent tropopause height changes.

Observations indicate that the height of the tropopause-the boundary between the stratosphere and troposphere-has increased by several hundred meters since 1979. Comparable increases are evident in climate model experiments. The latter show that human-induced changes in ozone and well-mixed greenhouse gases account for approximately 80% of the simulated rise in tropopause height over 1979-1999. Their primary contributions are through cooling of the stratosphere (caused by ozone) and warming of the troposphere (caused by well-mixed greenhouse gases). A model-predicted fingerprint of tropopause height changes is statistically detectable in two different observational ("reanalysis") data sets. This positive detection result allows us to attribute overall tropopause height changes to a combination of anthropogenic and natural external forcings, with the anthropogenic component predominating.

Journal Article↗
PubMed2003

Influence of satellite data uncertainties on the detection of externally forced climate change.

Two independent analyses of the same satellite-based radiative emissions data yield tropospheric temperature trends that differ by 0.1 degrees C per decade over 1979 to 2001. The troposphere warms appreciably in one satellite data set, while the other data set shows little overall change. These satellite data uncertainties are important in studies seeking to identify human effects on climate. A model-predicted "fingerprint" of combined anthropogenic and natural effects is statistically detectable only in the satellite data set with a warming troposphere. Our findings show that claimed inconsistencies between model predictions and satellite tropospheric temperature data (and between the latter and surface data) may be an artifact of data uncertainties.

Journal Article↗
PubMed2001

Enhancement of complement-mediated lysis by a peptide derived from SCR 13 of complement factor H.

Complement factor H (fH) is an important regulator of complement activation. It contributes to protection of cells against homologous complement attack. In this study we tested the effect of fH-depletion of normal human serum (NHS) on lysis of antibody-coated sheep and human erythrocytes (EshA and EhuA). In the absence of fH, lysis of sensitised Esh and Ehu was clearly increased. Addition of fH to fH-depleted serum re-established protection of cells against complement similar to that seen with NHS. A fH-derived peptide (pepAred), covering the N-terminal half of SCR 13 in fH, was able to enhance complement-mediated lysis of EhuA significantly. However, the oxidised form of this peptide (pepAox) had no effect. Biotinylated pepAred, but not pepAox, was able to directly bind to cells. Additionally, pepAred competed with direct fH-cell interaction which was observable only after treatment of purified fH with mercaptoethanol. Only pepAred increased the amount of C3 fragments and reduced levels of fH detectable on cells as shown by FACS analysis and radio-immuno assay. Furthermore, fH and factor I (fI)-mediated cleavage of agarose bound C3b into iC3b was decreased in the presence of pepAred. These data indicate that a fH-derived peptide can enhance complement-mediated lysis. We will continue to investigate whether the use of a fH peptide can be exploited for therapeutical purposes.

Amino Acid Sequence↗
PubMed1979

[Preoperative administration of antacids to prevent Mendelson's syndrome in pregnant women receiving general anesthesia (author's transl)].

Preoperative administration of 15 mls of the antacid Andursil to women undergoing surgical procedures in GA during pregnancy does reduce the risk of aspiration pneumonitis (Mendelson-Syndrome) from 1:3,5 to 1:15,5. The data show that the number of risk patients is increased in early stages of pregnancy and--surprisingly--in patients undergoing elective surgery. Pains and costs of prophylactic antacids are negligible. Neonates of LSCS patients receiving an antacid are not at an increased risk. As a conclusion the prophylactic administration of oral antacids to all pregnant women having a GA is recommended.

Anesthesia, General↗