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994 results on '"Ungerstedt, U."'

13. Analyte flux through chronically implanted subcutaneous polyamide membranes differs in humans and rats

Author

Wisniewski, N., Rajamand, N., Adamsson, U., Lins, P. E., Reichert, W. M., Klitzman, B., and Ungerstedt, U.

Subjects
Transplantation immunology -- Research, Immunological tolerance -- Measurement, Wound healing -- Physiological aspects, Biological sciences
Abstract

The rat is commonly used to evaluate physiological responses of subcutaneous tissue to implanted devices. In vivo longevity of various devices and the biocompatibility of biomaterials depend on how adjacent tissue interacts. How closely the rat model predicts the human response has not been well characterized. The objective of this study was to compare rat and human subcutaneous foreign body responses by monitoring the biochemical environment at a polymer-tissue interface over 8 days using microdialysis. Polyamide microdialysis probes were implanted subcutaneously in humans and rats (n = 12). Daily microdialysis samples were analyzed for glucose, lactate, pyruvate, glycerol, and urea. Blood glucose was also monitored. Analyte concentrations differed significantly between rats and humans at the implant-tissue interface. There were also qualitative differences in the 8-day trends. For example, over 8 days, microdialysate glucose increased two- to fourfold in humans but decreased in rats (P < 0.001). This study reveals profound physiological differences at material-tissue interfaces in rats and humans and highlights the need for caution when extrapolating subcutaneous rat biocompatibility data to humans. wound healing and foreign body responses; microdialysis; diffusion; glucose monitoring; biosensor biocompatibility

Published
2002

17. Metabolite levels in human skeletal muscle and adipose tissue studied with microdialysis at low perfusion flow

Author

Rosdahl,, H., Hamrin, K., Ungerstedt, U., and Henriksson, J.

Subjects
Muscles -- Research, Perfusion (Physiology) -- Research, Dialysis -- Methods, Adipose tissues -- Research, Biological sciences
Abstract

Research was conducted to examine metabolite levels in human skeletal muscle and adipose tissue using microdialysis at low perfusion flow. The objective of the study was to identify a perfusion flow wherein the interstitial fluid in human skeletal muscle and adipose tissue completely equilibrates with the microdialysis perfusion fluid with respect to glucose, glycerol, urea and lactate. Results suggest that microdialysis at a low perfusion flow have the potential to continuously monitor tissue interstitial concentrations.

Published
1998

26. Intrastriatally injected c-fos antisense oligonucleotide interferes with striatonigral but not striatopallidal gamma-aminobutyric acid transmission in the conscious rat

Author

Sommer, W., Rimondini, R., O'Connor, W., Hansson, A.C., Ungerstedt, U., and Fuxe, K.

Subjects
Rats -- Genetic aspects, Antisense nucleic acids -- Research, Proto-oncogenes -- Research, Neuroplasticity -- Genetic aspects, Science and technology
Abstract

Antisense c-fos oligonucleotides injected into the neostriatum of conscious rats selectively inhibited c-fos expression associated with compensatory increases in striatal c-fos mRNA levels and also with increased expression of junB and NGFI-A mRNA, probably as a result of regulatory phenomena. Dual probe in vivo microdialysis was used to investigate [Gamma]-aminobutyric acid (GABA) release in the substantia nigra and the globus pallidus, which represent the terminal sites of the dopamine [D.sub.1] receptor regulated striatonigral and the dopamine [D.sub.2] receptor regulated striatopallidal GABA pathways, respectively. Intrastriatal infusion of the c-fos antisense oligonucleotide profoundly decreased dialysate GABA levels in the ipsilateral substantia nigra within 60 min but did not influence the dialysate GABA levels in the globus pallidus compared with the sham and control oligonucleotide treated groups. The site of action of the antisense oligonucleotides was mainly restricted to striatal neurons as shown by the distribution of locally injected fluoresceine isothiocyanate and radiolabeled oligonucleotides. The findings demonstrate a facilitatory role for c-fos mediated gene regulation in striatonigral GABA transmission and strengthen the evidence that the regulation of neurotransmission is different in the striatonigral and striatopallidal GABA pathways.

Published
1996

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