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Biomedical subjects

F Keller

Publications and source records attributed to F Keller.

At least 271 records · Page 15Linked to original sources
PubMed1986

Towards a new classification of intracellular particle movements based on quantitative analyses.

A survey study of organelle movements in a variety of cell types of plant and animal origin was made with the aid of video-enhanced contrast, differential interference contrast (AVEC-DIC) microscopy followed by fine analysis of the motile behavior of the individual organelles. We found that there exists besides Brownian motion a wide spectrum of active motions in cells, i.e. motion that is directionally biased through the expenditure of metabolic energy. The types of active motion seen range from a continuous motion (sometimes appearing as streaming) in plant cells and neurons to various types of less ordered and less well directed motion. We did not see any clear-cut qualitative difference between plant and animal cells or between systems presumed to be actin- and microtubule-based. A preliminary classification of the types of active motion is presented. The ongoing research activities, which aim at a more precise definition of the different types of motion by a set of quantitative parameters, are described, and the progress made so far is reported.

Animals↗
PubMed1986

Muscarinic receptors in slice cultures of rat brain.

Muscarinic acetylcholine receptors in organotypic slice cultures of hippocampus of the rat, have been examined using the tritiated muscarinic antagonist quinuclidinylbenzilate [( 3H]QNB) as a as a marker. Maximum specific binding of [3H]QNB in mature explants of hippocampus amounted to 316 fmol/mg protein and a dissociation constant (KD) of 185 pM was determined. Scatchard analysis suggested binding to one single binding site. In younger cultures smaller KDs were registered. This decrease in ligand affinity in maturer cultures possibly reflects a decrease in the turnover of acetylcholine. Muscarinic antagonists inhibited the total binding of [3H]QNB significantly, whereas muscarinic agonist, nicotinic antagonists and cholinesterase inhibitors had no influence whatsoever on the total binding of [3H]QNB. The content of muscarinic acetylcholine receptors varied between cultures with explants from different brain areas: hippocampus greater than striatum greater than septum greater than spinal cord greater than cerebellum. These in vitro results are generally in good agreement with results obtained in situ by other investigators and suggest that the binding of [3H]QNB observed in these cultures is indeed correlated to specific muscarinic receptor sites.

Animals↗
PubMed1986

[Preventive use of antibiotics in kidney transplantation].

Antibiotic prophylaxis in kidney transplantation is controversial. In a prospective controlled study, 34 cadaveric kidney transplant recipients were investigated. Antibiotic prophylaxis was given in a random order to 16 patients whereas 18 without prophylaxis served as controlls. In 4 of 20 investigated clinical parameters statistically significant differences were found between both groups: the controlls happened to have better initial conditions; perioperative and postoperative better initial conditions; perioperative and postoperative infections were less frequent in the prophylaxis group and more antibiotics postoperatively were needed in the controlls. These findings indicate that antibiotic prophylaxis has a beneficial effect in kidney transplantation.

Bacteriological Techniques↗
PubMed1986

[Procedure for the biological testing of substances in the guinea pig subcutaneous test. I. The results of an improved semiquantitative assessment of the histological criteria].

Different materials were implanted into the subcutaneous connective tissue of guinea pigs to evaluate biotolerance by means of the tissue response. The investigations were carried out with reference materials and newly developed implant materials in short-term studies and in case control studies. The semiquantitative valuation standards lead mostly only to informing statements in the sense of a compatibility degree. Alternative assertions are possible when comparing very different materials.

Animals↗
PubMed1986

[Procedure for the biological testing of substances in the guinea pig subcutaneous test. II. The results of mathematical evaluation and modelling of the morphometric data on the area of reaction].

The extent of the reaction area around implanted materials (connective tissue capsule) was measured by the electronic device system Densitron and was represented in its temporal dependence after implantation. A histocompatibility index (referring to titanium as reference material) was deduced from the course of the connective tissue adaptation (healing in process). Linear regression calculation shows that the healing in process can be described very well by means of a power function for the most of the investigated materials. A clear demarcation and classification of the tissue tolerance of the different materials was managed for the histocompatibility index and also by the obvious integral values of the experimentally found out and mathematically modelled subsidence curves of the connective tissue reaction (selected period: 90th to the 200th day after the implantation).

Animals↗
PubMed1986

[Procedure for the biological testing of substances in the guinea pig subcutaneous test. III. The results of the quantitative determination of the cell division pattern in the area of reaction].

The counting of the type of cells in the surroundings of implanted materials enables the estimation of specific material effects and improved the statement of the biologic testing methods. The explained method is described in the example of reference materials and is applied to different new materials for the estimation of their histocompatibility.

Animals↗
PubMed1986

[Methodological aspects of the photometric determination of prothrombin time using chromogenic substrates].

A method for photometric determination of prothrombin time (PT) with a chromogenic peptide as substrate is described. The reagent contains human placental thromboplastin, a chromogenic substrate, calcium, a heparin antagonist and buffer. The new prothrombin time method has been calibrated against international reference preparations for thromboplastin. The reagent is sensitive to deficiency of all coagulation factors of the extrinsic pathway. However, it is not sensitive for heparin up to 1 IU/ml. The precision of this fast and simple method is comparable to that of mechanised assays for clinical chemistry.

Blood Coagulation↗
PubMed1985

[Characteristics of terminal analgesics-induced nephropathy].

The diagnosis of analgesic-associated nephropathy (AAN) may be missed because of the patients denial or regular analgesic intake. We therefore performed a cross-sectional study of the 144 patients of our hemodialysis center to investigate differences between the 48 patients with AAN (33%) and patients with other kidney diseases who served as controls. The aim was to find other attributes of analgesic users relating to social history, habits and morbidity. Dialysis patients with AAN were significantly older (60 +/- 10 versus 52 +/- 15 years) and more frequently women (65% versus 37%) compared with controls; they often had a family history of analgesic abuse. Comparison with an age-matched control group of hemodialysis patients with other kidney diseases showed that AAN patients smoked, used hypnotics and laxatives, and required prescriptions significantly more frequently; they were less frequently willing to undergo renal transplantation. With regard to accompanying diseases, they suffered significantly more often than the age-matched controls from anemia, renal osteodystrophy, peptic ulcer disease, diverticulosis, hemorrhoids, atrial fibrillation, coronary heart disease, hyperlipidemia, carpal tunnel syndrome, and urinary tract infections. The characteristic pattern of habits, social history and accompanying diseases may facilitate the diagnosis of AAN even in cases where analgesic consumption is denied.

Age Factors↗
PubMed1985

In vitro antiviral properties of endotoxin-activated rat Kupffer cells.

Kupffer cells isolated from the liver of normal rats were checked for their antiviral activities. The intrinsic antiviral effect against vaccinia virus was high whether the cells were activated in vitro with endotoxin or not. The expression of the extrinsic antiviral activity measured by mixing isolated Kupffer cells with vaccinia-virus-infected target cells was remarkably enhanced by prior treatment of the Kupffer cells with LPS. Interferon was shown to be not responsible for that inhibitory activity. Different experimental data suggest that the virus replication in the target cells is blocked at a late stage in the replication cycle.

Animals↗
PubMed1985

Development of cholinergic projections in organotypic cultures of rat septum, hippocampus and cerebellum.

ChAT and AChE activity in the hippocampus originate primarily in axons from cholinergic neurons located in the medial septum. The development of cholinergic projections in organotypic explant cultures of rat septum, hippocampus, cerebellum and habenula was studied using AChE histochemistry and biochemical ChAT and AChE determinations. Hippocampal and cerebellar explants cultured without a septum contain negligible amounts of ChAT after 6 days of culture. When the hippocampus was cultured for several days in the presence of a septal explant, a massive increase in ChAT was observed in the hippocampal explant. When co-cultures were stained for AChE, AChE-positive projections were seen to grow out from the septum to invade the hippocampal explant. To a certain extent this ingrowth of septal cholinergic fibers into the hippocampus is target-specific, since cerebellar explants cultured with septum showed neither an ingrowth of AChE-containing septal fibers, nor an increase in ChAT activity. Also, habenular AChE-positive fibers fail to grow into a co-cultivated hippocampal explant. Further, in septal explants co-cultivated with hippocampal explants an increase in ChAT activity was seen as compared to septal explants cultivated alone. The possible factors responsible for the observed specificity and the increase in ChAT activity under co-culture conditions are discussed.

Acetylcholinesterase↗
PubMed1985

Haemodialysis in 'hepatorenal syndrome': report on two cases.

We report two patients with hepatorenal syndrome who recovered from oliguria and renal failure after temporary treatment with haemodialysis. Hepatorenal syndrome developed under diuretic treatment in both patients. Volume expansion, dopamine, and prostaglandin I2 did not improve renal function. In the one patient with alcoholic cirrhosis, renal biopsy showed only minimal alterations of glomeruli, tubuli, and arterial vessels. In the other case, the deterioration and improvement in renal function parallelled changes in acute alcohol-toxic hepatic function. We conclude that haemodialysis should be considered for treatment of hepatorenal syndrome in selected patients where reversal of liver failure can be expected.

Acute Kidney Injury↗
PubMed1985

Low cyclosporin A blood levels and acute graft rejection in a renal transplant recipient during rifampin treatment.

Cyclosporin A trough blood levels were unusually low during rifampin treatment in a kidney transplant patient. Simultaneously, acute graft rejection occurred. Pharmacokinetic investigation revealed a rapid turnover of cyclosporin A leading to low blood levels. Cessation of rifampin therapy reversed these changes. Rifampin substantially reduces the bioavailability of cyclosporin A and should not be used in transplant recipients on cyclosporin A.

Adult↗
PubMed1985

Antimicrobial therapy in dialysis patients. II. Remaining antibiotics and antimicrobiologic agents.

Antimicrobial therapy in hemodialysis patients is made possible by pharmacokinetic dosage modifications. The problem is that overdosage produces side effects whereas therapeutic drug action is missed by underdosage. The dose should be calculated to achieve identical peak levels (for bactericidal drugs) as in normal renal function or identity of AUC (for bacteriostatic drugs). Antimicrobial therapy is started with a loading dose which usually equals the dose in patients with normal renal function. The maintenance dose is reduced in renal failure and adjusted to the increase in the dominant elimination half-life. The effect of hemodialysis must be taken into account and replacement of the removed fraction by a supplementary dose is needed to assure therapeutic drug action.

Aminoglycosides↗
PubMed1985

Value of human chorionic gonadotropin measurements in blood as a pregnancy test in women on maintenance hemodialysis.

Human chorionic gonadotropin (hCG beta) values were determined in the blood of 19 women and 4 men on maintenance hemodialysis. Blood samples were taken 3 times at an interval of 1 week. Measurements were done by an hCG beta RIA kit (Serono). The median hCG beta values were 9 mIU/ml (range 0-116) in 7 menstruating women, 6 (0-25) in 11 postmenopausal women and 0 (0-7) in 4 men. There was no statistically significant difference between the 3 groups. The median hCG beta values in all 3 groups were below the upper normal limit. However, the individual measurements varied considerably with elevation in 32% of 52 measured values (10-fold elevation in 2 cases). We conclude that in the blood of non-pregnant women on chronic hemodialysis, elevated hCG beta values can be found, erroneously indicating an intact pregnancy of 3-5 weeks duration or a nonintact pregnancy (e.g. impending abortion, extrauterine gravidity).

Chorionic Gonadotropin↗
PubMed1985

Fatal relapse in Goodpasture's syndrome 3 years after plasma exchange.

Since 1919 about 400 cases with Goodpasture's syndrome have been published, and since 1975 about 100 of these patients were treated with plasma exchange in addition to immunosuppression. A remission was achieved in 50% of the 100 cases, and in 7 a relapse was reported. In this paper, we are reporting a case with a fatal relapse 3 years after successful plasma exchange treatment. This patient was a smoker, she had been exposed to hydrocarbon solvents, and she had the HLA tissue antigens DR2 and MT3. Lung biopsy by fiberoptic bronchoscopy revealed linear staining of IgG at the alveolar basement membrane. During relapse pulmonary infiltrations and macrohematuria did not respond a second time to methylprednisolone pulses nor to plasma exchange treatment and the patient died of massive lung hemorrhage.

Adult↗