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Biomedical subjects

F Wunderlich

Publications and source records attributed to F Wunderlich.

At least 55 records · Page 3Linked to original sources
PubMed1991

Testosterone and other gonadal factor(s) restrict the efficacy of genes controlling resistance to Plasmodium chabaudi malaria.

The effect of circulating concentrations of testosterone (Te) on resistance to Plasmodium chabaudi malaria was investigated in the H-2 congenic mouse strains C57BL/10, B10.A, B10.A(3R), B10.A(4R), and B10.D2. Te-levels were determined by radioimmunoassay and resistance was expressed in terms of percent self-healers after challenge with 10(6) P. chabaudi-infected erythrocytes. Our data indicate: (i) Females and castrated males reveal very similar interstrain variations of resistance. These do not correlate with the interstrain variations of the Te-levels. This is consistent with the view that resistance to P. chaubaudi is controlled by genes of the H-2 complex and genes of the non-H-2 B10-background, (ii) The polygenic control of resistance is inefficacious at high Te-levels. This is evident as high susceptibilities of males, Te-treated females and Te-treated castrated males. Moreover, high Te-levels correlate with susceptibilities to P. chabaudi within mice of the same sex of a given strain, (iii) B10-males chemically castrated using buserelin display the same low Te-level as those surgically castrated. The latter become resistant, while the former remain as highly susceptible to P. chabaudi as untreated B10-males. Obviously, other gonadal factor(s), besides Te, impose restrictions on genes controlling resistance to P. chabaudi malaria.

Alleles↗
PubMed1991

Testosterone-induced abrogation of self-healing of Plasmodium chabaudi malaria in B10 mice: mediation by spleen cells.

This study investigates the suppressive effect of testosterone (Te) on the self-healing of Plasmodium chabaudi malaria in female mice of the strain C57BL/10, and, in particular, the possible role of spleen cells in mediating this Te effect. Our data show the following. (i) About 80% of B10 mice infected with 10(6) P. chabaudi-infected erythrocytes are capable of self-healing the infections. This capability is progressively impaired and finally abrogated after pretreating the B10 mice with Te for 3 weeks. (ii) The spleen is Te responsive. This becomes evident in a reduction of total spleen cells from 1.05 x 10(8) to 0.54 x 10(8) on average after Te treatment for 3 weeks. Moreover, Te treatment causes an increase in the relative proportion of CD8+ cells by about 4% and a decrease of Ig+ cells by about 4.5%, as revealed by flow cytometry. (iii) Spleen cells mediate the suppressive Te effect as revealed by adoptive transfer experiments. The percentage of self-healing mice dramatically decreases to about 8% when they receive, just prior to infection, nucleated spleen cells isolated from mice treated with Te for 3 weeks. This suppressive effect can be transferred by T cells in particular but also by non-T cells, though to a lesser extent. (iv) The adoptively transferred cells mediate their suppressive effect on self-healing only if the recipient mice receive Te during infection. Our data suggest that spleen cells become functionally changed by the Te treatment for 3 weeks. Particularly T cells, but also non-T cells, gain P. chabaudi-specific suppressive activities, and the cells require a Te-induced factor(s) to mediate these activities.

Animals↗
PubMed1988

Cryptic disposition of antigenic parasite proteins in plasma membranes of erythrocytes infected with Plasmodium chabaudi.

Plasma membranes of Plasmodium chabaudi-infected erythrocytes contain seven major neoproteins with apparent molecular masses of 154, 145, 90, 72, 67, 52, and 33 kDa, respectively. These neoproteins, with the exception of the two larger ones, can be metabolically labelled with [14C]isoleucine. The seven neoproteins are antigenic as revealed by Western blotting using hyperimmune sera obtained from two different mouse strains. None of the parasite proteins is accessible from the outside in intact P. chabaudi-infected erythrocytes as determined by lactoperoxidase-mediated radioiodination, indirect immune fluorescence microscopy, or post-embedding immunoelectron microscopy. These methods, however, identify parasite proteins in host cell plasma membranes when the latter are artificially changed either during isolation or by methanol fixation. We conclude therefore that parasitic proteins are cryptically arranged in intact host cell plasma membranes of P. chaubaudi-infected erythrocytes.

Animals↗
PubMed1988

Plasmodium chabaudi malaria: protective immunization with surface membranes of infected erythrocytes.

Plasmodium chabaudi-susceptible NMRI and B10.A mice were vaccinated with host cell plasma membranes isolated from P. chabaudi-infected erythrocytes. Most of the mice were protected from the lethal consequences of challenge with the homologous parasite, although protection was unassociated with a reduction in the course or peak of parasitemia. Vaccination also induced the production of antibodies against Pc90, which is the immunodominant protein expressed by parasites in host cell plasma membranes.

Animals↗
PubMed1988

Resistance to Plasmodium chabaudi in B10 mice: influence of the H-2 complex and testosterone.

Resistance to Plasmodium chabaudi has been examined in different inbred mouse strains bearing identical H-2 haplotypes on different genetic backgrounds as well as in H-2-congenic mouse strains on B10 background. Resistance is expressed in terms of percent survival after a challenge with 10(6) P. chabaudi-infected erythrocytes. We can show that murine resistance to P. chabaudi is under complex polygenic control involving a non-H-2 gene(s) as well as genes in both I-A and I-E subregions of the H-2 complex. Our data indicate in particular that malaria protective antigens can be presented in context with I-Ab molecules but not in context with I-Ak molecules. Resistance controlled by I-Ab does not become apparent when I-Ek molecules are coincidentally expressed. Moreover, testosterone abrogates I-Ab-controlled resistance to P. chabaudi.

Animals↗
PubMed1988

Expression of the parasite protein Pc90 in plasma membranes of erythrocytes infected with Plasmodium chabaudi.

Erythrocytes infected with the malaria parasite Plasmodium chabaudi contain the neo-protein Pc90 in their plasma membrane. We investigate origin, membrane disposition, and intraerythrocytic traffic of this Pc90. Metabolic labeling of P.-infected erythrocytes, combined with cell fractionation as well as Western blot analysis and immunoprecipitation using a Pc90-recognizing monoclonal antibody, show that Pc90 is synthesized by early to mid trophozoites and is transported without any apparent processing steps to the erythrocyte membrane. Based upon the inaccessibility of Pc90 from the outside in intact erythrocytes and the water solubility of membrane-associated Pc90, it is concluded that Pc90 is localized on the cytoplasmic face of the host erythrocyte membrane. Immunoelectron microscopy using a Pc90-specific monoclonal antibody and the occurrence of soluble Pc90 in host cell cytosol indicate that the Pc90 is transported in both a 'vesicle-bound' and a 'free' form through the erythrocyte cytoplasm.

Animals↗
PubMed1987

Isolation and characterization of parasites and host cell ghosts from erythrocytes infected with Plasmodium chabaudi.

A new procedure has been developed which allows the concomitant isolation of viable parasites and host cell plasma membranes from erythrocytes infected with Plasmodium chabaudi trophozoites. The average final yield of parasites is 56%. Free parasites reveal a well preserved ultrastructure, incorporate [14C]isoleucine for at least 3 h, and synthesize about the same proteins as parasites within erythrocytes as monitored by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)-autoradiography. The host cell plasma membranes can be isolated in the form of ghosts with an average yield of 27%. The ghosts possess a structurally intact plasma membrane as revealed by freeze-etch electron microscopy. The ghosts are regularly associated with seven neo-proteins as identified by SDS-PAGE and isoelectric focusing (IEF)/SDS-PAGE. These neo-proteins have the following apparent molecular masses: 154 kDa, 145 kDa, 90 kDa, 72 kDa (pI 4.5), 67 kDa, 52 kDa, and 33 kDa (pI 5.7), respectively. The contamination of ghosts by parasite material and, conversely, the contamination of parasites by host cell plasma membranes is very low as demonstrated by light and electron microscopy, lactoperoxidase-mediated radioiodination and the distribution of the typical parasite marker enzymes such as choline kinase, cholinephosphotransferase and ethanolaminephosphotransferase.

Animals↗
PubMed1987

Electron microscopical studies on cutaneous leishmaniasis in Ethiopia. II. Parasite and host cell differences between the localized and the diffuse form.

The ultrastructure of Leishmania aethiopica parasites and their host cells was investigated in lesions of 7 patients suffering from diffuse cutaneous leishmaniasis (DCL) and in lesions of 4 patients with localized cutaneous leishmaniasis (LCL). The appearance of host cells and parasites varied considerably in both disease forms. Host cell variations occurred especially in the number of cytoplasmic vesicles, the size of the parasitophorous vacuoles, and the number of amastigotes per parasitophorous vacuole. Differences concerned the occurrence of a special macrophage-type in DCL-lesions which was characterized by an electron-translucent cytoplasm and a low degree of parasitization, larger parasitophorous vacuoles with higher numbers of amastigotes per vacuole in infected macrophages from DCL-patients, and the number of electron dense granules in host cell vacuoles of DCL-patients. The parasites inducing DCL and LCL significantly differed in size and membrane structure: Amastigotes had a length of 2.27 +/- 0.48 micron and a width of 1.77 +/- 0.40 micron in DCL-lesions, and 1.92 +/- 0.40 micron and 1.48 +/- 0.32 micron in LCL-lesions. Promastigotes obtained from DCL-patients revealed 2078 +/- 308 integral membrane particles (IMP)/micron2 and 892 +/- 246 IMP/micron2 on the P- and E-fracture faces of plasma membranes, while the corresponding values of LCL-derived promastigotes amounted to 1690 +/- 376 IMP/micron2 and 652 +/- 274 IMP/micron2, respectively.

Animals↗
PubMed1986

Cutaneous leishmaniasis in Ethiopia: I. Lymphocyte transformation and antibody titre.

The Ethiopian cutaneous leishmaniasis (ECL) caused by Leishmania aethiopica manifests itself in two different forms: The self-healing localized form (LCL) and the non-self-healing diffuse cutaneous leishmaniasis (DCL). In patients suffering from these two forms of ECL, the Leishmania antigen induced in-vitro lymphocyte response and the Leishmania specific antibody titres were investigated. Whole promastigotes and a soluble fraction thereof were used as antigens and antibody titres were determined by a newly developed enzyme-immunosorbent assay (ELISA). Mononuclear cells from the majority of patients but not from healthy donors proliferated in response to soluble Leishmania antigen. In contrast, whole promastigotes induced a proliferation in both patients and controls. Only DCL-cases failed to proliferate in response to both leishmanial antigens. On the average, sera from DCL-patients contained higher titres of Leishmania specific antibodies than those from LCL-patients. One practical implication of these results is that lymphocyte proliferation in combination with specific antibody titre can be used as a reliable diagnostic tool in ECL.

Adolescent↗
PubMed1985

Fractionation of Plasmodium chabaudi-infected erythrocytes into parasites and ghosts.

We have developed a new procedure for subfractionation of Plasmodium chabaudi-infected erythrocytes into parasites and ghosts. Trophozoite-infected erythrocytes enriched over a percoll-step (:1.10 g/cm3) are subjected to a glycerol-enhanced osmotic shock. This induces the release of parasites and the emergence of erythrocyte ghosts, which can be separated on a continuous percoll gradient (:1.02----1.10 g/cm3). The parasites are intact in terms of ultrastructure and incorporation of 14C-isoleucine. The erythrocyte ghosts are purified over a two-step percoll gradient (:1.01-1.02 g/cm3). Our method recovers about 40%-50% of the initial ghosts and 70%-95% of the initially freed parasites.

Animals↗
PubMed1984

Thermal diminution and augmentation of the retention of transportable rRNA in nuclear envelope-free nuclei.

We have examined the effect of temperature on the rRNA transport from nuclei isolated from Tetrahymena after removal of both nuclear membranes and pore complexes by 1% Triton X-100. These nuclei export rRNA as precursor ribosomal ribonucleoprotein particles at both 28 degrees C and 8 degrees C which are qualitatively the same in terms of rRNA pattern, sedimentation coefficients and buoyant densities. At 8 degrees C, however, significantly fewer ribosomal ribonucleoprotein particles can be maximally exported than at 28 degrees C, though nuclei contain enough potentially transportable particles. These are increasingly released with increasing temperatures. Under conditions non-permissive for export, temperature elevation decreases the number of the potentially transportable ribosomal ribonucleoprotein particles in nuclei. Our data show: transportable ribosomal ribonucleoprotein particles inside nuclei are not 'free', but rather are subject to a complex temperature-sensitive retention: this retention is gradually diminished under export conditions and augmented under non-permissive export conditions with increasing temperatures. These retention mechanisms operate at an intranuclear level preceding the ribosomal ribonucleoprotein passage through the nuclear envelope pore complexes, i.e., the nuclear envelope regulates neither the number of potentially transportable ribosomal ribonucleoprotein particles in nuclei nor the number of those particles which can be maximally exported from nuclei at a given temperature. We suggest that these retention mechanisms involve temperature-sensitive domains of the nuclear matrix.

Animals↗
PubMed1984

Thermal down-regulation of exportable rRNA in nuclei.

The export of rRNP particles from nuclei isolated from Tetrahymena was investigated after preincubating the nuclei at different temperatures under nonpermissive export-conditions. We observed a new phenomenon: Temperature elevation from the sublethal cells' growth temperature, 8 degrees C, to the optimal temperature, 28 degrees C, lead to a gradual down-regulation in the maximal proportion of rRNP particles subsequently exported from nuclei at 28 degrees C. This thermal down-regulation is apparently not due to qualitative changes in the exported rRNP particles, a derangement in the gross nuclear organization, a degradation and/or nicking of the nuclear rRNA, a gross decomposition of the major nuclear proteins, a random cross-linking of nuclear components by disulfide bonds, or an elution of nuclear factors possibly required for rRNP export. Moreover, there is a corresponding thermal down-regulation in nuclear envelope-free nuclei. Our data indicate that nuclei possess a mechanism that regulates the number of potentially exportable rRNP particles at a level preceding the rRNP passage through the nuclear envelope.

Animals↗
PubMed1983

In vitro ribosomal ribonucleoprotein transport. Temperature-induced "graded unlocking" of nuclei.

We examine the effect of temperature on the export of ribosomal precursor particles from nuclei isolated from Tetrahymena. A new phenomenon is observed. Temperature does affect not only the export rate, but also the maximal portion of particles exported. At 8 degrees C, for example, the export kinetics reveals a significantly lower saturation plateau which does not equilibrate with the higher plateau at 28 degrees C even after 3 h. This nonequilibration is not due to (i) a different physical quality of the exported particles, (ii) a degradation of the nuclear rRNA, (iii) a backward import of exported particles into nuclei, (iv) an irreversible inactivation of potentially transportable nuclear ribosomal ribonucleoprotein (rRNP) particles, or (v) a thermodynamic equilibrium between transportable rRNP particles associated with nuclei and those exported from nuclei. We conclude, therefore, that potentially transportable rRNP particles are somehow "locked" in nuclei at low temperature and temperature raising induces a "graded unlocking."

Animals↗
PubMed1983

In vitro nuclear transport of ribosomal ribonucleoprotein: temperature affects quantity but not quality of exported particles.

The in vitro export of ribosomal ribonucleoprotein (rRNP) from Tetrahymena nuclei was investigated at the optimal growth temperature of 28 degrees C and at the nonlethal temperature of 8 degrees C. At both temperatures, nuclei exported ribosomal precursor particles that revealed the same physical qualities of size, appearance in negative-staining electron microscopy, sedimentation coefficient, buoyant density, and rRNA pattern. Surprisingly, fewer rRNP particles were exported at 8 than at 28 degrees C, as was revealed by a lower saturation plateau in the export kinetics from nuclei prelabeled with [3H]uridine. Upon a temperature increase from 8 to 28 degrees C, additional rRNP particles were exported. We conclude that nuclei export only a defined portion of rRNP particles at a given temperature, although enough potentially transportable rRNP particles are present in nuclei. Obviously, the reactivity of at least one of the reactants involved directly or indirectly in rRNP export changes with temperature.

Biological Transport↗
PubMed1982

Temperature-induced vertical shift of proteins in membranes.

Thermotropic changes in the transverse order of microsomal membranes isolated from Tetrahymena are revealed by low-angle X-ray diffraction. These are correlated with the lateral order of the membrane lipids by wide-angle X-ray diffraction. Upon lowering the temperature from 28 degrees C to 2 degrees C, the Bragg period of the membrane stack reveals an abrupt increase of approximately 3.1 nm at approximately 19 degrees C, which is reversible upon reheating to 28 degrees C. This is coupled with an alteration in the electron density profile, revealing a shift of mass from the hydrophobic core towards one of the two hydrophilic surfaces. Between 35 degrees C and 0 degrees C, the membrane lipids undergo a broad, thermotropic "two-stage" liquid crystalline in equilibrium crystalline phase separation with a "breakpoint" at approximately 18 degrees C. This breakpoint signals an abrupt lipid redistribution, presumably due to a change in the composition of the two coexisting liquid crystalline and crystalline lipid phases. We conclude: (1) the temperature-induced mass shift reflects a shift in the transverse partition of proteins in membranes; (2) this is triggered by an abrupt lipid redistribution occurring during a broad liquid crystalline in equilibrium crystalline phase separation.

Fatty Acids↗
PubMed1982

Thermotropic 'two-stage' liquid crystalline equilibrium crystalline lipid phase separation in microsomal membranes.

The effect of temperature on native microsomal membrane vesicles isolated from Tetrahymena is investigated by wide angle X-ray diffraction. A 4.2 reflection, typical for lipids in the crystalline state, can be recorded in the temperature range between 0 degree C and 35 degrees C. Quantitative evaluation of this reflection reveals a broad thermotropic 'two-stage' liquid crystalline equilibrium crystalline lipid phase separation with a 'breakpoint' at approx. 18 degrees C. This 'breakpoint' coincides with the emergency of lipid-protein segregations in endomembranes of intact Tetrahymena cells as previously visualized by freeze-etch electron microscopy.

Animals↗