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Biomedical subjects

W Haas

Publications and source records attributed to W Haas.

At least 91 records · Page 5Linked to original sources
PubMed1988

Chemical signals of fish skin for the attachment response of Acanthostomum brauni cercariae.

The chemical signals of the skin surface of fish, which stimulate the attachment responses of Acanthostomum brauni cercariae, were identified by offering chemicals and fish-skin extracts in agarose substrates to the cercariae. Smaller molecules such as amino acids, fatty acids, monosaccharides, electrolytes, urea, and carbonate solutions did not stimulate attachments, but hyaluronic acid had some effects. Bovine submaxillary glycoproteins had a strong stimulating activity that disappeared after neuraminidase digestion. The stimulating components of the skin surface of fish were hydrophilic substances with molecular weights of more than 10,000. They were sensitive to neuraminidase digestion but not to hyaluronidase digestion and thus can be identified as glycoproteins. A. brauni cercariae respond only to the complete glycoprotein molecules and not to their monosaccharide components. The known attachment triggers of other cercariae are small molecules. Large glycoproteins as host signals for A. brauni cercariae may be an adaptation to muddy habitats, where various substances with low molecular weights may interfere with the host identification.

Amino Acids↗
PubMed1988

Host-finding in Trichobilharzia ocellata cercariae: swimming and attachment to the host.

The cercaria of Trichobilharzia ocellata finds and identifies its duck host with a series of different behavioural phases. Dispersal and selection of the water surface as microhabitat is achieved by an intermittent swimming behaviour, which is governed by the interplay of passive dropping with forward and backward swimming movements and includes a positive phototactic and a geonegative orientation. Then the cercariae tend to cling to the water surface in an energy-saving resting position. A movement towards the duck feet as the site of entry occurs when shadows evoke forward swimming movements, which are directed away from the source of light, i.e. normally downwards. Forward swimming movements are also stimulated by touch, but only in free-swimming cercariae and not when these are in the resting position. Attachments occur only when a substrate is touched during forward swimming movements. Attachments are stimulated by warm substrates (1 degrees C temperature difference triggers a nearly maximal response) and by chemical components of duck-foot skin, and the readiness to attach is increased when the forward swimming movement is started by shadow stimuli.

Animals↗
PubMed1988

Trichobilharzia ocellata: chemical stimuli of duck skin for cercarial attachment.

Trichobilharzia ocellata cercariae attach readily to the foot skin of their duck host, but poorly to preen-gland contents. The attachment to duck foot disappears when the skin surface lipids are extracted, and can be restored by reapplication of the lipids to the skin. Hydrophilic skin extracts are without any effect. Thin-layer chromatographic fractionation of duck-foot skin surface lipids reveals cholesterol and ceramides as attachment stimuli. A stimulation of cercarial attachment by these hydrophobic host signals is supported by the host identification pattern of the cercariae, which secures a close contact with encountered substrates.

Animals↗
PubMed1987

CTLA-1 and CTLA-3 serine esterase transcripts are detected mostly in cytotoxic T cells, but not only and not always.

We and other investigators previously reported the cloning of CTLA-1 (or CCP-1) and CTLA-3 (or H Factor) serine esterase-related transcripts preferentially expressed in cytolytic T lymphocytes. We extended the survey of the tissue specificity of these molecules. Two main sets of results were obtained. First, both CTLA-1 and CTLA-3 transcripts could be found in the various cytolytic T cells tested, although in widely different amounts, and in some cases just at the threshold of detection. Secondly, these transcripts were not found in most of the other cells tested, including in some natural cytotoxic cells and in activated cytotoxic macrophages; however, they could be detected in mast cells for CTLA-1 and in some noncytotoxic lymphocytes for CTLA-3. Thus, the CTLA-1 and CTLA-3 serine esterase products are most probably not required for macrophage or natural cytotoxicity; their presence cannot be taken as characteristic of cytotoxic T cells; and a discussion about their relevance to T cell-mediated cytotoxicity should take into account their widely different amounts from one cytotoxic T cell to another.

Animals↗
PubMed1987

Host identification by Schistosoma japonicum cercariae.

Attachment, the first phase of host identification by Schistosoma japonicum cercariae, can occur in 2 different ways. Cercariae clinging to the water surface simply swing around and transfer to the host skin. Free-swimming cercariae behave like S. mansoni: upon touching a substrate, they switch from tailward to forward movement, swim in an arc, and attach to it with the penetration organ. Neither type of attachment is influenced by chemical, thermal, or specific mechanical stimuli from the host. The second phase, remaining on the host, requires a solid hydrophobic surface and seems to depend only on the cercaria's ability to cling to it. This phase is not influenced by chemical or thermal stimuli. The third phase, creeping across the host surface, is independent of chemical and mechanical stimuli. Cercariae migrate in thermal gradients to a preferred temperature of 37 +/- 3 C and then attempt to penetrate. Penetration, the fourth phase, was evoked by human skin surface lipids. The free fatty acid (FA) fraction was identified as exclusively stimulating components. Saturated FA's were effective at chain lengths between 10 and 14 carbon atoms (pH 7.0), and unsaturated FA's were effective at longer chains and their activity increased with increasing number of double bonds. Dog skin surface components did not stimulate cercarial penetration, which can be attributed to the lack of free FA's. A temperature of 32-40 C also stimulated penetration responses, which might be the main stimulus in animal hosts, whose skin surfaces contain no or only a few free FA's. FA's and heat evoked a transformation of cercarial tegument simultaneous with penetration behavior, making the organisms osmotically sensitive. The host identification of S. japonicum cercariae is very nonspecific compared with the differentiated host recognition of S. mansoni.

Adhesiveness↗
PubMed1987

[Acoustic evoked brain stem potentials in chronic alcoholic Korsakoff syndrome].

29 patients with Korsakoff syndrome (KS) were examined by means of brainstem auditory evoked potentials. The interpeak-latencies were delayed cumulative with the most accentuation of IPL I-VI. BAEP are suitable for subdividing of KS. It is suggested that BAEP shall observed in alcoholics for detection of norm-deviations.

Alcohol Amnestic Disorder↗
PubMed1986

Idiotope-specific T cell clones that recognize syngeneic immunoglobulin fragments in the context of class II molecules.

We have established idiotope (Id)-specific T cell lines and clones derived from at least 4 different BALB/c mice immunized with the light chain (lambda 2(315] of the BALB/c myeloma protein M315 (alpha, lambda 2). Independently derived clones were indistinguishable in that they reacted to V lambda 2(315), one or more of the amino acids corresponding to somatically mutated codons 94, 95 and 96 of the third hypervariable region being essential for expression of the Id. While the Id was efficiently expressed on V lambda 2(315), Fv315 and lambda 2(315) fragments, about a 100-1000-fold higher molar concentration of Fab315 and M315 was needed to induce equivalent responses. Thus, Ig quaternary structure heavily influenced the availability of the Id for T cells. The V lambda 2(315)-specific T cells were Thy-1.2+, L3T4+, Ly-2.2- and I-Ed restricted. Some of the T cell clones produced interleukin 2 (IL2), IL3 and B cell growth and differentiation factors upon activation. In addition, T cells were cytotoxic in long-term assays for Ed beta Ek alpha-, but not Ek beta Ek alpha- transfected L cells in the presence of Id. The cytotoxic effect was the basis for an L cell growth inhibition assay for T cell activation that was at least 10-fold more sensitive than ordinary proliferation assays.

Animals↗
PubMed1985

Cytolytic T cell hybridomas. I. Interleukin 2-independent noncytolytic variants.

Fluorescein-specific cytolytic hybrids were obtained by fusion of an interleukin 2 (IL2)-dependent murine cytotoxic T lymphocyte clone with the thymoma BW5147. The hybrid cells grow and retain cytolytic activity in medium with recombinant IL2. In medium without IL2 rare variants can be selected which grow in the absence of exogenous IL2; these variants are not cytolytic. Anti-IL2 receptor antibodies bind to and inhibit the growth of the cytolytic hybrids while they do not bind to and do not inhibit the growth of the variants. The cytolytic hybrids as well as the non-cytolytic variants produce interferon gamma in response to antigen. These findings indicate that the noncytolytic IL2-dependent variants lost IL2 receptors but not antigen receptors.

Animals↗
PubMed1985

Cytolytic T cell hybridomas. II. Interleukin 2-independent cytolytic variants.

Interleukin 2 (IL2)-dependent cytolytic hybrids usually loose IL2 dependence and cytolytic activity concomittantly. Here we describe an exceptional IL2-independent variant which lost IL2 receptor but retained cytolytic activity. When the IL2-independent cytolytic hybrid cells were fused with IL2-dependent cytolytic clones which express IL2 receptors constitutively, IL2-dependent hybrids were obtained. This suggests that the expression of IL2 receptors can interfere with IL2-independent growth mechanisms.

Animals↗
PubMed1985

Cytolytic T cell hybridomas. III. The antigen specificity and the restriction specificity of cytolytic T cells do not phenotypically mix.

We have obtained cytolytic T-T hybrids by fusing an H-2Kk restricted clone specific for the hapten 3-(p-sulfophenyldiazo)-4-hydroxyphenyl acetic acid (SP) with an H-2Dd-restricted clone specific for the hapten fluorescein (FL). Several hybrid clones express both parental specificities but fail to lyse SP-coupled H-2Dd and FL-coupled H-2Kk target cells. We also fused the H-2Kk-restricted, SP-specific clone with a clone which recognizes FL in the context of any class I major histocompatibility complex antigen. Again several hybrids show both parental specificities but fail to recognize SP coupled to target cells which are not recognized by the parental SP-specific clone. These findings indicate that the observed cytotoxic T lymphocyte specificities for haptens on the one hand and polymorphic as well as nonpolymorphic class I major histocompatibility complex antigenic determinants on the other hand are not carried by independent proteins.

Animals↗
PubMed1985

Studies on the attachment response of Isthmiophora melis cercariae (Trematoda: Echinostomatidae).

The cercaria of Isthmiophora melis is relatively specific to suitable intermediate hosts, amphibia and fish, as early as the stage of attachment. Attachment responses are maximally stimulated by intact amphibia, whereas isolated frog tissues have a reduced efficiency. Human urine contains attachment triggering substances. Its effectiveness is reduced, when carbonate systems are removed, and may be restored by addition of carbonate. Aqueous solution systems of dissolved CO2 and H2CO3/HCO-3 stimulate attachment responses, especially at pH 6.0-7.5. The attachment response to frog skin surface seems to be triggered by the buffering system, which uses carbonate solution equilibria as important components.

Amino Acids↗