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Biomedical subjects

C Pfister

Publications and source records attributed to C Pfister.

At least 109 records · Page 6Linked to original sources
PubMed1987

[Changes in the mast cell content of the lamina propria mucosa of the small intestine in enteral-induced growth disorders in childhood].

Duodenal jejeunal biopsy material from children with growth retardation due to enteric disease was investigated. The disease dependent mucosa types were classified into three groups according to Shmerling (1970). Mucosa types and established histological alterations can be correlated. Toluidine blue staining sections were analyzed morphometrically by light microscopy to study changes in the mucosal mast cells. The mast cell content in specimens with subtotal villal atrophy (type III) was reduced significantly compared to normal mucosa (type I).

Antigen-Presenting Cells↗
PubMed1986

Activation of retinal rod cyclic GMP-phosphodiesterase by transducin: characterization of the complex formed by phosphodiesterase inhibitor and transducin alpha-subunit.

The GTP-binding subunit of transducin (T alpha) activates the cGMP phosphodiesterase (PDE) of bovine retinal rods by relieving the constraint imposed by the inhibitory subunit PDE gamma. We have isolated and characterized the complex T alpha.GTP gamma S-PDE gamma formed when T alpha is activated by the nonhydrolyzable analog GTP gamma S. Sedimentation and light-scattering techniques demonstrate that, in contrast to free T alpha.GTP gamma S, which is soluble, the T alpha.GTP gamma S-PDE gamma complex, as well as T alpha.GTP-PDE gamma, is membrane bound at cytosolic ionic strength. It is eluted from the membrane at low ionic strength as a monomeric and 1:1 stoichiometric complex. The relative affinities of PDE gamma for PDE alpha beta and for T alpha.GTP are discussed.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1985

Fluoroaluminates activate transducin-GDP by mimicking the gamma-phosphate of GTP in its binding site.

Fluoride activation of the cGMP cascade of vision requires the presence of aluminum, and is shown to be mediated by the binding of one A1F-4 to the GDP/GTP-binding subunit of transducin. The presence of GDP in the site is required: A1F-4 is ineffective when the site is empty or when GDP beta S is substituted for GDP. This sensitivity to the sulfur of GDP beta S suggests that A1F-4 is in contact with the GDP. Striking structural similarities between A1F-4 and PO3-4 lead us to propose that A1F-4 mimics the role of the gamma-phosphate of GTP.

Aluminum↗
PubMed1985

Retinal S antigen identified as the 48K protein regulating light-dependent phosphodiesterase in rods.

Retinal S antigen chromatographically purified from whole retina, induces experimental autoimmune uveoretinitis in laboratory animals. The 48K protein, a soluble protein found in rod outer segments, is purified through its specific binding to photoexcited rhodopsin and is involved in the quenching of light-induced guanosine 3',5'-monophosphate-phosphodiesterase activity. Biochemical, immunological, functional, and pathological tests showed that retinal S antigen and the 48K protein are identical.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1985

Inhibition of hormonally regulated adenylate cyclase by the beta gamma subunit of transducin.

Transducin (T), the GTP-binding protein of the retina activates the cGMP phosphodiesterase system, and presents analogies with the proteins GS and Gi which respectively mediate adenylate cyclase activation and inhibition by hormone receptors. These proteins are all comprised of an alpha subunit carrying the GTP-binding site and a beta gamma subunit made of two peptides. The beta peptide (35 kd) appears similar in the three proteins. We demonstrate here that purified T beta gamma inhibits adenylate cyclase from human platelet membranes. This inhibition was observed when adenylate cyclase was stimulated by GTP, prostaglandin E1 (PGE1), NaF and forskolin, but not when stimulated by GTP(gamma)S. In the presence of GTP and forskolin, the T beta gamma-induced maximal inhibition was not additive with the alpha 2-receptor-induced adenylate cyclase inhibition mediated by Gi. Both inhibitions were suppressed at high Mg2+ concentrations, which as also known to dissociate T beta gamma from T alpha-GDP. This suggests that these adenylate cyclase inhibitions are due to the formation of inactive complexes of GS alpha-GDP with T beta gamma or Gi beta gamma. T beta gamma-induced inhibition did not require detergent and could be suppressed by simple washing. T beta gamma effects are dependent on its concentration rather than on its total amount. This suggests that T beta gamma can operate in solution with no integration into the membrane. Similar inhibitory effects of T beta gamma are observed on adenylate cyclase from anterior pituitary and lymphoma S49 cell lines.

Adenylyl Cyclase Inhibitors↗
PubMed1984

Guanine nucleotides and magnesium dependence of the association states of the subunits of transducin.

When GTP gamma S is bound to transducin (T), the two subunits T alpha X GTP gamma S and T beta gamma dissociate, independently of the ionic environment. When GDP is bound, these subunits are associated as a monomeric T alpha X GDP-T beta gamma complex of 75 kDa when the ionic environment is comparable to that of the cytoplasm, but they dissociate in the presence of 10-100 mM Mg2+ or Ca2+. Using this property, the subunits could be separated and purified by a rapid one-step procedure on an ion-exchange column (FPLC), and their molecular masses were verified by neutron small angle scattering. The physiological relevances of the dissociating effect of Mg2+ are discussed.

Animals↗
PubMed1984

[Cellular distribution of substance P in the rat adrenal medulla].

Substance P-like immunoreactivity (SPLIR) has been found in fibres and the surroundings of ganglion cells and in a new cell type of rat adrenal medulla, using the indirect immunohistochemical method. These SPLIR-cells are characterized by their localization in the connective tissue in close vicinity of vessels and by acidophilic staining in HE-procedure. Relationships are discussed between the localization of substance P in the adrenal medulla and possible interactions with catecholamines with respect to stress.

Adrenal Medulla↗
PubMed1984

[Morphological changes in the neurons of the rat nucleus raphe dorsalis following application of 5,7-dihydroxytryptamine. A golgi-rapid-impregnation study].

The effect of stereotactically applicated 5,7-dihydroxytryptamine on the demonstrability of the different neuron types of the nucleus raphe dorsalis of the rat was investigated by means of the Golgi-rapid-impregnation technique. Degenerative changes could be demonstrated on the polygonal neurons, only. Typical variations of the dendritic structure was shown on the fusiform neurons. The pyriform neuron typ was not affected.

5,7-Dihydroxytryptamine↗
PubMed1984

[Identification of the so-called 48 K protein that interacts with illuminated rhodopsin in retinal rods, and the retinal S antigen, inductor of experimental autoimmune uveoretinitis].

In Vertebrate retinal rod outer segments, a soluble "48 K" protein binds to disk membranes upon illumination in presence of ATP or GTP (H. Kühn, Biochemistry, 17, 1978, p. 4389). Its binding to photoexcited rhodopsin implies a probable role of the "48 K" protein in the ATP dependent regulation of the photoinduced enzymatic cascade which controls the hydrolysis of cGMP. The "retinal S antigen" is also a soluble protein located in photoreceptor cells which is known to be an organ-specific auto-antigen inducing experimental autoimmune uveoretinitis. Using extracts of purified cattle and frog rod outer segments, purified bovine S antigen, and monoclonal antibodies against S antigen, we found that both proteins exhibit identical characteristics with respect to: their migration in SD S-gel electrophoresis; their binding to rod disc membranes upon illumination in presence of ATP or GTP; their immunological reactivity with monoclonal antibodies.

Animals↗
PubMed1983

Interaction between photoexcited rhodopsin and peripheral enzymes in frog retinal rods. Influence on the postmetarhodopsin II decay and phosphorylation rate of rhodopsin.

The major peripheral and soluble proteins in frog rod outer segment preparations, and their interactions with photoexcited rhodopsin, have been compared to those in cattle rod outer segments and found to be similar in both systems. In particular the GTP-binding protein (G) has the same subunit composition, the same abundance relative to rhodopsin (1/10) and it undergoes the same light and nucleotide-dependent interactions with rhodopsin in both preparations. Previous work on cattle rod outer segments has shown that photoexcited rhodopsin (R*), in a state identified with metarhodopsin II, associates with the G protein as a first step to the light-activated GDP/GTP exchange on G. The complex R*-G is stable in absence of GTP, but is rapidly dissociated by GTP owing to the GDP/GTP exchange reaction. Low bleaching extents (less than 10% R*) in absence of GTP therefore create predominantly R*-G complexes, whereas bleaching in presence of GTP creates free R*. We report here that, under conditions of complexed R*, two reactions of R* in frog rod outer segments are highly perturbed as compared to free R*: (a) the spectral decay of metarhodopsin II (MII) into later photoproducts, and (b) the phosphorylation of R* by an ATP-dependent protein kinase. a) The spectral measurements have been performed using linear dichroism on oriented frog rod outer segments; this technique allows discrimination between MII and later photoproducts absorbing at the same wavelength. Association of R* with G leads to a strong reduction of the amount of MIII formed and to an acceleration of the decay of MIII. Furthermore, MII is significantly stabilized, in agreement with the hypothesis that MII is the intermediate which binds to G. b) The phosphorylation of R* is strongly inhibited under conditions of R*-G complex formation as compared to free R*. Interferences between reactions at the three sites involved in R* are discussed: the retinal binding site in the hydrophobic core is sensitive to the presence of GTP-binding protein at its binding site on the cytoplasmic surface of R*; the kinase and the GTP-binding protein compete for access to their respective binding sites, both located on the surface of R*. We also observed a slow and nucleotide-dependent light-induced binding of a protein of molecular weight 50 000, which we consider as the equivalent of the 48 000 Mr light-dependent protein previously identified in cattle rod outer segments.

Adenosine Triphosphate↗
PubMed1983

[Morphometric comparison of neuron types in the nucleus raphe dorsalis and nucleus centralis superior (Nc. raphe medianus) of the rat].

Three similar neuron types (polygonal, fusiform and pyriform neurons) were found to exist in populations of the nucleus raphe dorsalis and of nucleus raphe medianus, resp. The neuron types of both subnuclei were compared morphometrically using sections prepared by means of the Einarson--technique. The comparison between morphometrical values (size and breadth of the somata and nuclei, resp.) of the neuron types didn't show significant differences.

Animals↗
PubMed1983

[Morphometric studies on the effect of 5-hydroxytryptamine creatinine sulfate and noradrenaline bitartrate on the growth of cerebral cortex explants in vitro].

Explants of cerebral cortex of neonatal rats were cultivated up to 15 DIV being treated with 5-hydroxytryptamine and noradrenaline, resp. Effects of exogenous transmitters on the growth of explants were investigated by means of morphometrical methods. Different effects on the growth depending on the duration of cultivation and the type of transmitter administered were found. Stimulatory influences have been seen to occur up to 4 DIV (noradrenaline) and up to 2 DIV (serotonin).

Animals↗
PubMed1983

[Neuron typing of the nucleus centralis superior (nucleus raphe medianus) of the rat].

The nucleus centralis superior (Nucleus raphe medianus) of the adult rat was investigated by means of the rapid Golgi impregnation technique. Three neuron types could be distinguished: polygonal neurons exhibiting somatic spines, fusiform neurons, and small sized pyriform neurons. An strikingly conformity of the morphological characteristics of the neuron types in the nucleus centralis superior and in the nucleus raphe dorsalis, resp., was found.

Animals↗