Biomedical subjects

P Henklein

Publications and source records attributed to P Henklein.

77 records · Page 5Linked to original sources

PubMed1985

[Effect of desaminoocta-pancreozymin on the locomotor activity of rats].

The influence of desaminoocta-pancreozymin (DAO-PZ) was investigated in high and low activity periods by intraperitoneal or intranasal application. DAO-PZ is a CCK-8 derivative in which the N-terminal amino acid (Asp) is exchanged for succinyl acid. A decreasing long lasting effect for 3 to 4 h was always observed in locomotor activity. A food reduction was also proved after i. p. and intranasal application. The effects correspond to those of CCK-8 reported in the literature. They are discussed in this respect.

Animals↗

PubMed1979

[The effect of a synthetic tripeptide nervous tissue cultured in vitro].

Explants from chick embryo PNS (ganglion trigeminale) and from CNS of embryonal rats (hippocampus) and dissociated cells from chick embryo cerebral hemispheres were cultivated in maximow chambers in the presence of various concentrations of placental serum and of a chemically synthesized tripeptide Gly-His-Lys. 1. The presence of tripeptide in the nutrient medium with a low concentration of serum did not compensate the outgrowth of nerve fibers, that take place in the growth medium. 2. In the presence of tripeptide in the nutrient medium with low concentration of serum the index of growth area increased significantly. 3. Within the first days in cell cultures 0,01 microgram tripeptide pro ml medium stimulated the outgrowth of neuronal processes. 4. The experiments indicated, that the tripeptide did not replace the serum. The possible role of tripeptide as a system in controlling neuron-glial ratio in vitro is discussed.

Animals↗

PubMedDate not supplied

Synthesis, characterization, and biological properties of cyanine-labeled somatostatin analogues as receptor-targeted fluorescent probes.

We present the synthesis and characterization of the somatostatin receptor-specific peptide H(2)N-(D-Phe)-cyclo[Cys-Phe-(D-Trp)-Lys-Thr-Cys]-Thr-OH, which is labeled with a carboxylated indodicarbo- and an indotricarbocyanine dye at the N-terminal amino group. The preparation was performed by automated solid-phase synthesis, with subsequent attachment of the cyanine dye and cleavage of the entire conjugate from the resin. The compounds display high molar absorbance and fluorescence quantum yields typical for cyanine dyes and are thus suitable receptor-targeted contrast agents for molecular optical imaging. The ability of these agents to target the somatostatin receptor was demonstrated by flow cytometry in vitro, in which the indotricarbocyanine conjugate led to elevated cell-associated fluorescence on somatostatin receptor-expressing tumor cells. In contrast, the corresponding linearized derivative of the sequence H(2)N-(D-Phe)-Met-Phe-(D-Trp)-Lys-Thr-Met-Thr-OH produced only minimal cell fluorescence, hence confirming the specificity of the cyclic somatostatin analogue. Intracellular localization could be visualized by near-infrared (NIR) fluorescence microscopy. In conclusion, receptor-specific peptides are promising tools for designing site-directed optical contrast agents for use in molecular optical imaging.

Animals↗

PubMedDate not supplied

Replacement of fetal calf serum in cell cultures by an egg yolk factor with cholecystokinin/gastrin-like immunoreactivity.

The in vitro culture of various cell types is an important scientific tool and is becoming increasingly acceptable as a viable alternative to animal experiments. Fetal calf serum (FCS) is a supplement used in many cell culture media, and provides cells with growth factors and cytokines necessary for successful culture. In view of the animal welfare issues surrounding the production of FCS, an alternative agent allowing the replacement or reduction in the use of FCS is desirable. A yolk extract factor (EYF-X) obtained from chicken eggs is described, which facilitates the in vitro culture of a variety of cell types. When the extract was added to a culture medium used for in vitro fertilisation, the number of successful fertilisations was significantly increased. In a further in vitro model (permanent neuronal cell line N2A), the yolk extract significantly stimulated cell proliferation as well as the growth of cell processes. A set of specific antibodies against different parts of the prepro-cholecystokinin reacted with the extract. The intensity of the reaction depends on the age of the egg (time after the laying date). Analysis by gel chromatography recorded a main protein fraction with an apparent molecular mass of 20-30kDa. This fraction was labelled by Western blot with an antibody with specificity against CCK-octapeptide. These findings suggest that the yolk factor may be a CCK/gastrin-like molecule. Since CCK/gastrin-like molecules have also been detected in the spermatozoa of mammals, the influence on in vitro fertilisation could be explained by the yolk factor replacing the endogenous CCK/gastrin-like molecule destroyed in sperm freezing. The results of this study suggest that it might be possible to replace FCS with EYF-X. The application of the yolk factor to a broad spectrum of cell types remains to be investigated.

Animal Use Alternatives↗

PubMedDate not supplied

Synthesis and characterization of the hydrophilic C-terminal domain of the human immunodeficiency virus type 1-encoded virus protein U (Vpu).

The HIV-1-specific virus protein U (Vpu) is an amphipathic membrane-associated phosphoprotein that probably possesses an N-terminal hydrophobic membrane anchor and a hydrophilic moiety. Because of an as yet undefined cytotoxic effect and the low concentration of Vpu in host cells, it has not been possible to obtain sufficient quantities of this protein for biochemical and structural investigations. We describe the synthesis, in two forms, of 50-residue peptides representing the polar cytoplasmic domain of Vpu: pVpu, comprising the wild-type Vpu sequence of HIV-1, strain HTLVIIIB, from position Ile32 to Leu81, and a mutant, pVpum2/6, with replacement of Ser52-56 with Asn. This mutation affects the two phosphorylation sites of Vpu for casein kinase-2 (CK-2), the enzyme that phosphorylates Vpu in HIV-1-infected cells. The peptides were purified to homogeneity and characterized by N-terminal sequencing, mass spectrometry and SDS-PAGE. Furthermore, both peptides were immunologically characterized by Western blot and ELISA using Vpu-specific monoclonal and polyclonal antibodies. Recombinant human CK-2 caused in vitro phosphorylation of pVpu, but had no effect on the mutant pVpum2/6. Investigation of the peptides by circular dichroism showed that addition of trifluoroethanol stabilized the alpha-helical secondary structure. Preliminary 1H NMR spectroscopic data indicated that, in the presence of trifluoroethanol, both peptides in solution have stable secondary structures with considerable alpha-helical content.

Acquired Immunodeficiency Syndrome↗