Biomedical subjects

L H Hekking

Publications and source records attributed to L H Hekking.

5 recordsLinked to original sources

PubMed2001

Rat models in peritoneal dialysis.

BACKGROUND: It is widely accepted that the currently used dialysis solutions are not biocompatible with the peritoneal membrane. Therefore, animal studies have been performed to study different aspects of peritoneal dialysis. However, representative models mimicking the human situation are not yet available. METHODS: The effect of a single injection of peritoneal dialysis (PD) fluid on the cellular composition was studied. Thereafter, the effect of a single injection of PD fluid on bacterial clearing was tested over time. Finally, an in vivo rat model was established to study the effects of long-term exposure to PD fluid on the peritoneal membrane and the local host defence (peritoneal cells). RESULTS: In the rat model, long-term daily exposure is possible. The 'drop-out' after 9-10 weeks on the most commonly used PD fluid Dianeal 3.86%, however, is approximately 50% due to omental wrapping. In the remaining study group, large differences were observed (as compared with controls), especially with respect to morphological parameters. CONCLUSIONS: The rat peritoneal continuous exposure model seems to have potential for intervention studies, since it uses no additions, no antibiotics and no omentomectomy, and gives continuous long-term exposure to PD fluid. However, problems still remain: 'drop-out' is quite often seen and this non-uraemic exposure model does not totally mimic the situation present in continuous ambulatory PD patients.

Animals↗

PubMed2001

Effect of PD fluid instillation on the peritonitis-induced influx and bacterial clearing capacity of peritoneal cells.

BACKGROUND: The commonly used peritoneal dialysis fluids contain glucose as the osmotic agent. Heat sterilization leads to the formation of glucose degradation products which contribute, together with glucose, to the formation of advanced glycation end-products (AGEs). AGEs have been shown to be present in the peritoneal cavity. Methods have been developed to minimize the amount of glucose degradation products in peritoneal dialysis fluids. In a rat peritoneal dialysis model, we compare the effect of a commonly used peritoneal dialysis fluid, Gambrosol, with a newly developed peritoneal dialysis fluid, PD-Bio, on the influx and functional capacity of the peritoneal cells after 2 weeks of peritoneal dialysis fluid instillation. METHODS: Three groups of animals were used: rats received daily infusion with 15 ml of either 4% Gambrosol (group 1) or 4% PD-Bio (group 2), and a control group of animals did not receive fluid (group 3). After 2 weeks of PD fluid instillation, all the animals were injected with a 0.5 ml suspension containing 3x10(8) colony-forming units of Staphylococcus aureus. The in vivo bacterial clearing capacity was determined after 15 h. RESULTS: A statistically significant higher leukocyte influx was found in the control group compared with both PD fluid-injected groups. No statistical differences in bacterial clearing were observed among the three groups, although the number of bacteria recovered from the PD-Bio group tended to be lower than that from the Gambrosol group. Moreover, in both PD fluid instillation groups, the bacteria tended to be cleared more slowly compared with the control group. The number of mesothelial cells in the PD fluid groups was significantly greater than in the control group. CONCLUSION: No differences were observed in bacterial clearing capacity, leukocyte influx and mesothelial cell number after a 2 week exposure of the peritoneal cavity to Gambrosol vs PD-Bio.

Animals↗

PubMed2001

Accumulation of omental mast cells during peritoneal dialysis.

OBJECTIVE: New vessel formation has been reported in various tissues during peritoneal dialysis (PD). In that line, mast cells can produce factors such as tryptase, chymase, or basic fibroblast growth factor that might contribute to the formation of new vessels. In the present study, the association of mast cells with neovascularization during PD was investigated. METHODS: Rats received daily 10 mL infusions of conventional 3.86% glucose-containing PD fluid over a 10-week period. The infusions were delivered through a subcutaneously implanted mini access port that was connected by catheter to the peritoneal cavity. Untreated rats served as a control group. The number of blood vessels and of mast cells in the omentum were counted. Also, the number of peritoneal mast cells was determined. RESULTS: Chronic exposure to PD fluid resulted in an increased number of mast cells in the omentum. However, no clear correlation was found between the elevated number of omental blood vessels and the number of mast cells in the omentum or in the peritoneal cavity. CONCLUSIONS: Omental mast cells accumulated dramatically upon exposure to PD fluid. The actual role of accumulated omental mast cells in the induction of angiogenesis during PD should, however, be further investigated.

Animals↗

PubMed1998

Effect of peritoneal dialysis fluid measured in vivo in a rat-model of continuous peritoneal dialysis.

To study the long-term effects of dialysis fluids on the peritoneal cavity, an in vivo model for continuous peritoneal dialysis in rats was developed. Mini vascular access ports were implanted subcutaneously in the neck of the rats and an attached catheter was instilled into the peritoneal cavity. Rats were injected daily with 10 mL of standard 3.86% Dianeal or saline for a period up to 12 weeks. In the peritoneal cavity an initial increase in total cells was observed after 4 weeks of fluid instillation. This had declined after 12 weeks. A similar trend was also seen for macrophage and neutrophil numbers, whereas the percentage of lymphocytes kept increasing in time. An effect of fluid instillation was observed on the density and the morphology of the mesothelial monolayer of the rats. A higher density of cells was observed after 12 weeks, and foci of young mesothelial cells within activated mesothelium were found. The results show that the rat model presented can be compared with the situation in the peritoneal cavity of continuous ambulatory peritoneal dialysis (CAPD) patients, and therefore is suitable for intervention studies.

Animals↗

PubMed1995

Molecular cloning of three distinct cDNAs, each encoding a different adipokinetic hormone precursor, of the migratory locust, Locusta migratoria. Differential expression of the distinct adipokinetic hormone precursor genes during flight activity.

Three distinct cDNAs encoding the preproadipokinetic hormones I, II, and III (prepro-AKH I, II, and III), respectively, of Locusta migratoria have been isolated and sequenced. The three L. migratoria AKH precursors have an overall architecture similar to that of other precursors of the AKH/red pigment-concentrating hormone (RPCH) family identified so far. The AKH I and II precursors of L. migratoria are highly homologous to the Schistocerca gregaria and Schistocerca nitans AKH precursors. Although the L. migratoria AKH III precursor appears to be the least homologous to the Manduca sexta, Drosophila melanogaster, and Carcinus maenas AKH/RPCH precursors, we favor the opinion that the L. migratoria AKH III precursor is evolutionary more related to the M. sexta, D. melanogaster, and C. maenas AKH/RPCH precursors than to the AKH I and II precursors of S. gregaria, S. nitans, or L. migratoria. In situ hybridization showed signals for the different AKH mRNAs to be co-localized in cell bodies of the glandular lobes of the corpora cardiaca. Northern blot analysis revealed the presence of single mRNA species encoding the AKH I precursor (approximately 570 bases), AKH II precursor (approximately 600 bases), and AKH III precursor (approximately 670 bases), respectively. Interestingly, flight activity increased steady-state levels of the AKH I and II mRNAs (approximately 2.0 times each) and the AKH III mRNA (approximately 4.2 times) in the corpora cardiaca.

Amino Acid Sequence↗