Search PubMed⌕ Search

Biomedical subjects

W Haas

Publications and source records attributed to W Haas.

At least 109 records · Page 6Linked to original sources
PubMed1984

[Drowning, swimming pool death and other emergencies related to swimming].

In the Federal Republic of Germany, some 700 people drown every year. Of particular importance is the so-called swimming bath black-out that occurs while swimming under water, which must always be avoidable when the causes are known and appropriate precautionary measures taken. Of life-saving importance in a case of drowning is the rapid and proper use of first aid. The severe pulmonary injury induced by freshwater or salt water aspiration urgently requires the treatment of the victim in an intensive care unit of a hospital, even after successful resuscitation.

Adolescent↗
PubMed1984

Cytotoxic T cell responses to haptenated cells. IV. Requirements for in vivo priming.

Hapten-specific cytotoxic T cells (CTL) can be generated in cultures containing mouse spleen cells and hapten-coupled syngeneic stimulator cells. A response to sparsely hapten-coupled stimulator cells is only obtained with responder cells from immunized H-2k mice. Immunization was effective with hapten coupled to syngeneic, allogeneic or xenogeneic nucleated cells or membranes thereof. Hapten-coupled erythrocytes, bacteriophages or soluble proteins did not induce CTL precursors (CTL-P) nor responses of other lymphocytes which would interfere with the response of CTL-P. The results show that antigen presentation to CTL-P is very efficient in vivo. Haptens could be presented to and recognized by CTL-P only if coupled to surface membranes of nucleated cells.

Animals↗
PubMed1984

Schistosoma mansoni: cercaricidal effect of 2-tetradecenoic acid, a penetration stimulant.

Schistosoma mansoni cercariae are stimulated by 2-tetradecenoic acid (TDA) to penetrate agar substrates. TDA simultaneously causes tegumental transformation similar to that seen when cercariae transform to schistosomula, reduces the Cercarienhüllen reaction in immune human serum, and reduces larval tolerance to water. TDA damages cercariae that fail to penetrate or have no opportunity to do so. This damage apparently stems from increased tegumental permeability to water. Preincubation in TDA for 60 min reduces the percutaneous infectivity of cercariae to mice by from 95% at 0.2 ppm to 100% at 0.7 ppm TDA, but does not reduce the infectivity of subcutaneously injected cercariae. The interference with percutaneous infection seems to be entirely due to osmotic damage. TDA does not induce premature secretion of the acetabular glands or block host-recognition chemoreceptors. TDA may be a promising cercaricide for schistosomiasis control. It is highly specific for schistosome cercariae and is effective at low concentrations (0.2 to 0.7 ppm). Both cercariae and TDA tend to collect in the upper few millimeters of standing water. It is unlikely that cercariae can evolve resistance to a chemical that triggers the host penetration mechanisms.

Agar↗
PubMed1984

Lyt-2- T cell-independent functions of Lyt-2+ cells stimulated with antigen or concanavalin A.

Approximately 30% of cytolytic Lyt-2+ clones from primed mice are able to proliferate autonomously, i.e., independent of IL 2 derived from Lyt-2- cells after antigenic stimulation. H-2K- or -D-restricted induction of Lyt-2+ cells to autonomous proliferation requires Ia+ stimulator cells. A strict correlation was observed between the ability of Lyt-2+ clones to proliferative autonomously and to induce DH. Eventually, the growth of all Lyt-2+ cytolytic clones becomes dependent on exogenous IL 2, and their ability to induce DH is lost. Small Lyt-2+ cells can also be induced in primary cultures by antigen or concanavalin A to proliferate in the absence of exogenous IL 2. The frequency of autonomously proliferating small Lyt-2+ cells is the same as that of small Lyt-2+ cells proliferating in the presence of exogenous IL 2. IL 2 derived from Lyt-2- cells can augment proliferation of Lyt-2+ cells, but is not obligatory.

Animals↗
PubMed1984

The importance of drug ionization for the action of calcium-antagonists and related compounds.

pK-Values of Ca-antagonists and related cardiodepressive drugs have been measured by means of potentiometric microtitration. The presumable active species for all compounds investigated is the protonated molecule except nifedipine. This drug must exert its action via the uncharged form. From these results it could be concluded that protonization of ionizable nitrogen is one molecular prerequisite for voltage- or frequency dependence of action. Drug ionization does not correlate with the negative inotropic potency of the compounds investigated.

Calcium Channel Blockers↗
PubMed1983

[Remarks on the "pure alexia" syndrome--a case report].

The article describes a case with the "pure alexia" syndrome caused by an infarct of the arteria cerebri posterior sinistra during a diffuse cerebral vascular disease. The authors consider the alexia to be a consequence of difficulties in transcoding graphic into graphemic structures.

Aged↗
PubMed1982

Functional and phenotypic properties of subpopulations of murine thymocytes. I. The bulk of peanut agglutinin-positive Lyt-1,2,3 thymocytes lacks precursors of cytotoxic T lymphocytes responsive to interleukin 2 (T cell growth factor).

Thymocytes were separate according to their surface phenotype and tested for cytotoxic T lymphocyte (CTL) precursor function by stimulation with allogeneic or hapten-coupled cells, with or without addition of T cell growth factor (interleukin 2). The data show that only a minor subpopulation of thymocytes agglutinated by peanut agglutinin, expressing relatively high amounts of H-2K antigen, contained CTL precursors. The remaining population, approximately 80%, could not be induced to generate CTL, even in the presence of interleukin 2.

Animals↗
PubMed1982

Characterization of chemical stimuli for the penetration of Schistosoma mansoni cercariae. I. Effective substances, host specificity.

The stimulation of penetration of Schistosoma mansoni cercariae into agar was studied. This depends exclusively on chemical triggers whose specificity is analyzed in experiments with 230 chemicals. Only aliphatic hydrocarbon chains which have a polar as well as a nonpolar end group are effective. The effectiveness of saturated substances is limited, at pH 7.0, to chain lengths between 10 and 15 carbon atoms. Unsaturated substances are active at longer chain lengths. Their effectiveness is increased by the number of double bonds in the cis position, and these should not be placed too close to the nonpolar end of the chain. As well as double bonds, halogens, hydroxyl groups, and methyl side chains are equally effective. All penetration stimulating substances kill cercariae in free water, and the appropriate chemicals cause this lethality at very low concentrations. It is shown that the host recognition pattern at the stage of penetration is especially adapted to invasion of the human skin.

Agar↗
PubMed1982

Characterization of chemical stimuli for the penetration of Schistosoma mansoni cercariae. II. Conditions and mode of action.

The mode of action of chemical substances which trigger the penetration of S. mansoni cercariae into agar substrata is studied. The effectiveness of these substances is largely independent on their polarity and water solubility. Thus, they do not seem to act by a passive membrane permeation process, but they may interact with specific receptor sites, which are characterized. The receptor sites seem to respond to the following chemical characteristics of the stimulating aliphatic hydrocarbon chain: Carboxylic end group, lipophilic end group, chain length, cis-double bond. The penetration stimulating substances cause, even in cercariae in free water, a transformation of the tegument, manifested as a reduction of the Cercarienhüllen-Reaktion and a loss of osmotic protection.

Agar↗