Biomedical subjects

Günter Kamp

Publications and source records attributed to Günter Kamp.

3 recordsLinked to original sources

PubMed2005

Paradoxical effects of hypoxia-mimicking divalent cobalt ions in human endothelial cells in vitro.

Divalent cobalt ions (Co2+) induce the expression of hypoxia responsive genes and are often used in cell biology to mimic hypoxia. In this in vitro study we compared the effects of hypoxia and Co2+ on human endothelial cells and examined processes that are stimulated in hypoxia in vivo (proliferation and angiogenesis). We analyzed the expression of the hypoxia-inducible factor-1alpha (HIF-1alpha) under different hypoxic conditions (3% and nearly 0% O2) and Co2+ -concentrations (0.01-0.7 mM). As in hypoxia, the amount of HIF-1alpha protein was enhanced by exposure to Co2+ (did not correlate with mRNA amount). however, contrary to the results of hypoxia, in vitro-angiogenesis was inhibited after exposure to even low Co2+-concentrations (> or =0.01 mM). This led to the conclusion that although hypoxia signaling after Co2+ -exposure took place, further yet unknown Co2+ -induced event(s) must have occurred.

Cell Line↗

PubMed2004

Induced hyperactivity in boar spermatozoa and its evaluation by computer-assisted sperm analysis.

Hyperactivity, a form of sperm motility characterized by vigorous flagellar movements, has been proposed as essential for fertilization in mammals. The objective of the present study was to establish a method for inducing hyperactivity in vitro in boar spermatozoa and to define threshold values to differentiate between hyperactive and non-hyperactive spermatozoa by computer-assisted sperm analysis (CASA) as a prerequisite for analyzing the energy metabolism during hyperactivity. In TALP-HEPES medium, non-frozen boar spermatozoa were stimulated to hyperactivity by 50 micromol l(-1) Ca2+ within 15 min at 37 degrees C if 5 micromol l(-1) of the Ca2+ ionophore A23187 was present. If 25% seminal plasma was present, boar spermatozoa required higher Ca2+ concentrations (about 700 micromol l(-1)) for hyperactivity. Under both conditions, immobilization and head-to-head agglutination were low so that hyperactive spermatozoa could be analyzed for at least 40 min. The transition from normal to hyperactive movement was characterized by an increase in flagellar beat angle from 49 degrees +/- 12 degrees to 200 degrees +/- 36 degrees (n = 32) and a decrease in flagellar curvature ratio from 0.89 +/- 0.04 to 0.47 +/- 0.11 (n = 32). For quantification of hyperactive boar sperm, kinematic parameters of hyperactive and non-hyperactive spermatozoa were measured by CASA and statistically evaluated (receiver operating characteristic (ROC) curve analysis). The threshold values of the following four parameters were well suited for differentiating between hyperactive and non-hyperactive boar spermatozoa (ROC curve analysis: > 50% specificity at 100% sensitivity). Hyperactive boar spermatozoa showed mean lateral head displacement > 3.5 microm, curvilinear velocity > 97 microm s(-1), linearity < 32% and wobble < 71%. According to this multiparametric definition, induction of hyperactivity increased significantly (P < 0.0001) the fraction of hyperactive spermatozoa in semen samples from 5.1 +/- 4.3% (n = 13) to 48.3 +/- 6.6% (n = 7) in the absence and to 44.2 +/- 7.6% (n = 10) in the presence of 25% seminal plasma, while the overall percentage of motile spermatozoa did not change significantly.

Animals↗

PubMed2002

Software-supported image quantification of angiogenesis in an in vitro culture system: application to studies of biocompatibility.

Healing of soft tissue trauma and bone discontinuities following implantation involves acute inflammatory reactions and the formation of blood vessels (angiogenesis). During angiogenesis new capillary vessels arise from the existing vasculature. Endothelial cells (EC) are the major cell type involved in angiogenesis. Corrosion of orthopaedic metallic implant materials (e.g. CoCr alloys) can cause locally high concentrations of heavy metal ions in the peri-implant tissues. Some divalent metal ions (Co2+, Ni2+, Zn2+) lead to the activation of EC in vitro. Upon exposure to these ions. EC release cytokines and chemokines and increase the expression of cell surface adhesion molecules, which represents the pro-inflammatory phenotype. In this study we have examined whether metal ions influence the other endothelial aspect of wound healing, the angiogenic response. Therefore, we utilized an in vitro model of angiogenesis and examined the effects of divalent cobalt ions on the in vitro vessel formation. The quantification of the cobalt/ion-exerted effects on angiogenesis in vitro was performed using a contrast-rich vital staining and analysed by software-supported image quantification.

Alloys↗