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Biomedical subjects

S Kopf

Publications and source records attributed to S Kopf.

5 recordsLinked to original sources
PubMed2001

[Microinvasive laparoscopic cholecystectomy with 2 mm instruments. Presentation of the method and initial results].

Between September 1998 and May 1999, 498 patients underwent laparoscopic cholecystectomy. Of these, 301 patients were electively scheduled cases. Two hundred and sixty-seven patients (58.4%) patients were operated on with the standard laparoscopic technique (LC) and 34 (6.8%) with a new microinvasive technique (MLC) using self-developed 2-mm instruments. The technique of this microinvasive method is introduced and the first results are reported. These results encourage us to recommend our new method for selected cases.

Adult↗
PubMed2001

Compensatory mechanisms enhance hippocampal acetylcholine release in transgenic mice expressing human acetylcholinesterase.

Central cholinergic neurotransmission was studied in learning-impaired transgenic mice expressing human acetylcholinesterase (hAChE-Tg). Total catalytic activity of AChE was approximately twofold higher in synaptosomes from hippocampus, striatum and cortex of hAChE-Tg mice as compared with controls (FVB/N mice). Extracellular acetylcholine (ACh) levels in the hippocampus, monitored by microdialysis in the absence or presence of 10(-8)-10(-3) M neostigmine in the perfusion fluid, were indistinguishable in freely moving control and hAChE-Tg mice. Muscarinic receptor functions were unchanged as indicated by similar effects of scopolamine on ACh release and of carbachol on inositol phosphate formation. However, when the mice were anaesthetized with halothane (0.8 vol. %), hippocampal ACh reached significantly lower levels in AChE-Tg mice as compared with controls. Also, the high-affinity choline uptake (HACU) in hippocampal synaptosomes from awake hAChE-Tg mice was accelerated but was reduced by halothane anaesthesia. Moreover, hAChE-Tg mice displayed increased motor activity in novel but not in familiar environment and presented reduced anxiety in the elevated plus-maze test. Systemic application of a low dose of physostigmine (100 microgram/kg i.p.) normalized all of the enhanced parameters in hAChE-Tg mice: spontaneous motor activity, hippocampal ACh efflux and hippocampal HACU, attributing these parameters to the hypocholinergic state due to excessive AChE activity. We conclude that, in hAChE-Tg mice, hippocampal ACh release is up-regulated in response to external stimuli thereby facilitating cholinergic neurotransmission. Such compensatory phenomena most likely play important roles in counteracting functional deficits in mammals with central cholinergic dysfunctions.

Acetylcholine↗
PubMed1991

A new approach to adoptive immunotherapy of cancer using tumorcytotoxic macrophages grown from peripheral blood monocytes.

Clinical trials to evaluate the potential of adoptive immunotherapy in cancer patients have been restricted to the use of lymphoid effector cells. Of the other probably even more important host defense system against tumor growth, the mono-nuclear phagocyte system, only monocytes (mo) have been reinfused which, however, represent immature precursor cells and acquire full functional competence only upon further maturation. This is a report on 7 patients who received autologous macrophages (MO) grown in vitro from blood mo and activated by interferon-gamma (IFN gamma). Mononuclear cells were isolated from whole blood by cytapheresis and cultured for 7 days with 2% autologous serum on hydrophobic Teflon foils. Eighteen house before cell harvest, recombinant human IFN gamma was added at 200 IU/ml. Mo-derived MO were purified by counter-current elutriation. Starting with 10(8) MO cells, therapy was escalated up to the maximal number of MO obtainable from one single preparation cycle. Currently, 26 therapies have been performed with the maximal dose being 1.7 x 10(9) MO per infusion. Except for low grade fever (less than 38 degrees C), MO autografts were well tolerated, with no side effects observed. Biological response was followed by analyzing the serum levels of beta 2-microglobulin, neopterin, interleukin-6, tumor necrosis factor, and lysozyme. While in 3 out of 7 patients serum neopterin increased in response to MO therapy, other biological response parameters remained at pretreatment levels. Radiolabeled MO were shown to first accumulate in the lungs, then to pool into liver and spleen.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopterins↗
PubMed1979

Role of unstirred layer in intestinal absorption of phenylalanine in vivo.

The appearance rate of L- and D-phenylalanine in the venous blood of rat jejunal loops in vivo is increased up to 60% if the intraluminal solution is mixed more efficiently by the simultaneous perfusion of air. The effect decreases as the luminal concentration is increased to 100 mmol/l. Thus, the apparent Michaelis constants are by 50% lower in the case of the reduced unstirred layer (26 to 17 for L- and 9 to 6 mmol/l for D-phenylalanine). The enhancement of the absorption and the reduction of the Michaelis constants can be attributed to the reduction of the effective unstirred layer thickness by about 400--500 micrometer.

Air↗