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Biomedical subjects

F Kaufmann

Publications and source records attributed to F Kaufmann.

At least 37 records · Page 2Linked to original sources
PubMed1991

Brain abscess in childhood--long-term experiences.

A retrospective evaluation was performed on 28 cases of paediatric brain abscess (male: female ratio 2.5:1; mean age 9.4 years; range 2.8-16 years) diagnosed between 1967 and 1987. In 46%, congenital cyanotic heart disease was identified as a predisposing factor, likewise sinusitis, otitis media or mastoiditis in 29% and immunodeficiency in 11%. Pathogenesis remained unclear in 14%. Initial symptoms and signs were predominantly nonspecific; loss of consciousness occurred in 32% of cases, neurological deficit and seizures each in 25%. Since the availability of CT, both diagnostic delay after hospital admission and mortality were substantially reduced: mean delay from 8.4 to 3.0 days, and mortality from 23% to 0%. Seventeen patients (61%) had follow up examinations 9.6 years (mean) after the acute illness (range 1-21 years). Neurological sequelae were diagnosed in 35% of cases, epilepsy in 29%, epileptic potentials during EEG in 12%, and CNS scars in 50%. Psychological testing revealed no statistically significant differences compared to normal populations. CNS scars, and epilepsy and/or epileptic potentials were more common after excision (7 patients) when compared to patients treated by aspiration and/or antibiotics alone (21 patients). It is concluded that excision of brain abscess should be avoided whenever possible. Therapy of choice consists of the administration of adequate antibiotics with or without CT-guided needle aspirations.

Adolescent↗
PubMed1991

A new class of potent antiproliferative glycolipids.

The synthesis and biological activities of a new class of antiproliferative glycolipids with an unexpected broad spectrum of activity, including a human multidrug resistant cell line, are described. Chemically these compounds are glycolipids derived from N-acetyl-D-glucosamine and glycyrrhetinic acid (beta-aglycone). Peptidation of the glucoacids allyl 3 beta-[[2-acetamido-3-O-[(R)-1-carboxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranosyl]oxy]-11-oxo-12- oleanen-30-oate and (R,S)-2-methoxy-3-(octadecyloxy)propyl-2-acetamido-3-O-[(R)-1-carb oxyethyl]- 2-deoxy-4,6-O-isopropylidene-beta-D-glucopyranoside was successfully achieved after activation with O-benzotriazolyl-N,N,N',N' -tetramethyluronium hexafluorophosphate.

Acetylglucosamine↗
PubMed1990

Human multi-drug-resistant cancer cells exhibit a high degree of selectivity for stereoisomers of verapamil and quinidine.

An in vitro cell proliferation assay was developed to measure the capacity of substances to overcome multi-drug resistance (MDR). The assay is a modification of the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The inclusion of cell titration curves for each concentration of the resistance modifier (RM) allows the IC50 of the RM to be calculated and provides empirical correction of the cell survival curves for the effect of the RM when it is combined with a standard cytotoxic drug, vincristine. The resistance modification index (RMI) is defined as the ratio of the IC50 of vincristine obtained in control cultures divided by that measured in the presence of RM and is linearly related to the dose of RM. The RMI0.1, the RMI at a one-tenth the IC50 of the RM, provides a relative comparison between the activities of different RMs at non-toxic doses. The results obtained using the MDR cell line, KB-8-5, show that l-(-)-verapamil is approximately 4 times more active than d-(+)-verapamil in modifying MDR. The racemic mixture has an intermediate activity. A similar comparison between the epimers quinidine and quinine shows that, at equimolar doses, quinine has a higher RMI but, because it is more toxic, the RMI0.1 is about one-half of that of quinidine. These results demonstrate the importance of comparing the resistance-modifying activities of different compounds at doses relative to their own toxicity.

Cell Line↗
PubMed1990

[Endoscopic removal of ureteral calculi in the age of extracorporeal shockwave lithotripsy].

High success rates of the shock wave lithotripsy in the treatment of ureteral stones are only achieved by repeated sessions and auxiliary measures. Therefore no general therapy of choice can be established. If differentiation is made according to certain criteria the endoscopic removal of ureteral calculi still plays an effective role as a significant complement to the shock wave lithotripsy. With a primary success rate of 93% for the distal ureteral stone and a rate of 1.5% for severe complications the endoscopic removal of large and small ureteral calculi indicated by a high risk situation of a vain attempt of a spontaneous stone loss is presenting a highly effective and successful matter of therapy with low risk. These indications are considered unfavourable assumptions for a primary shock wave lithotripsy. The therapeutical concept, results and complications due to ureteroscopy are presented and compared with the shock wave treatment.

Adult↗
PubMed1989

Primary structures of five ribosomal proteins from the archaebacterium Halobacterium marismortui and their structural relationships to eubacterial and eukaryotic ribosomal proteins.

The complete amino acid sequences of ribosomal proteins L9, L20, L21/22, L24 and L32 from the archaebacterium Halobacterium marismortui were determined. The comparison of the sequences of these proteins with those from other organisms revealed that proteins L21/22 and L24 are homologous to ribosomal protein Yrp29 from yeast and L19 from rat, respectively, and that H. marismortui L20 is homologous to L30 from eubacteria. H. marismortui ribosomal protein L9 showed sequence homology to both L29 from yeast and L15 from eubacteria. No homologous protein was found for H. marismortui L32. These results are discussed with respect to the phylogenetic relationship between eubacteria, archaebacteria and eukaryotes.

Amino Acid Sequence↗
PubMed1989

Both homodimeric isoforms of PDGF (AA and BB) have mitogenic and chemotactic activity and stimulate phosphoinositol turnover.

Platelet-derived growth factor (PDGF) occurs as three dimeric isoforms, AA, BB, and AB, which were previously shown to bind to two receptors with different isoform-specificity, the A/B-type (binds all three isoforms) and the B-type (binds only PDGF-BB). Results from competition binding experiments with Swiss 3T3 cells suggest the existence of a third receptor type, which recognizes PDGF-AB and PDGF-BB. Furthermore, Swiss 3T3 cells and human dermal fibroblasts express different relative and absolute levels of these receptor types. In particular, Swiss 3T3 cells express 90,000 PDGF-AA binding sites (A/B-receptors) per cell, whereas human fibroblasts express only 20,000 A/B-receptors per cell. All three PDGF isoforms were tested in either cell type for their effect on DNA synthesis. PDGF-BB and PDGF-AA were also tested in Swiss 3T3 cells for their effect on inositol phospholipid metabolism and chemotaxis. Each isoform promoted all three processes dose-dependently, but there were differences in the maximum cellular responses elicited. These responses reflect the capacity of the cells to bind the individual isoforms. These results demonstrate that the previous distinctions in responsiveness to the different PDGF isoforms are primarily a consequence of the differences in the levels of surface expression of the various isoform-specific receptor types, rather than of the differences in the intrinsic activity of these isoforms. Furthermore, these results suggest that all types of PDGF receptors are capable of responding to their respective ligands by mediating phosphoinositide breakdown, chemotactic responses, and DNA synthesis. Whether they exhibit other functional differences remains to be seen.

Animals↗
PubMed1987

Hyperalgesia in spontaneous and experimental animal models of diabetic neuropathy.

Hyperactivity of nociceptive C-fibers has been recently described in diabetic BB/Wistar rats. This study assesses the association of hyperalgesia, using an analgesy-meter, with elevated glycosylated haemoglobin levels in three animal models of diabetic and nutritional neuropathies: Psammomys obesus (sand rat), streptozotocin-treated and galactose-fed rats. Pain threshold measurements (paw pressure test) and motor nerve conduction velocities were recorded in controls (n = 75), hyperinsulinaemic (n = 16), insulin-deficient (n = 46) und galactosaemic (n = 12) animals. The reproducibility of the paw pressure test, evaluated by a correlation coefficient, was statistically significant (p less than 0.001). When compared with their controls (396 +/- 18 g), the average pain threshold in young diabetic sand rats (309 +/- 17 g) was found to be markedly reduced and to correlate inversely (p less than 0.001) with their respective HbA1c levels (mean 4.9 versus 7.4%). Acute, subacute and chronic streptozotocin-diabetic rats displayed a reduction of pain threshold (p less than 0.001) associated with slowed motor nerve conduction velocities (p less than 0.001). Similarly, galactose-feeding over 4 weeks resulted in an elevation of glycosylated haemoglobin levels with significant (p less than 0.001) reductions of pain threshold and motor nerve conduction velocity. It is concluded that hyperalgesia is a constant feature of sensory dysfunction in spontaneous and experimental models of diabetic neuropathy.

Animals↗
PubMed1987

Infants' recognition of a face revealed through motion: contribution of internal facial movement and head movement.

The experiment reported here explores 3-month-old infants' ability to recognize a human face from a specific motion pattern lacking static facial features. A woman's face was covered with black makeup and numerous white triangles. It was videotaped while the woman was pretending to interact with a baby. A soft rubber mask was prepared likewise and was videotaped while being moved and deformed by hand. In one condition, the face or mask showed facial movement only, while in a second condition there was internal movement plus head movement. The two stimuli were presented either in upright or in upside-down orientation. Results of 48 subjects indicate that the discrimination of face and mask was easier when the stimuli were presented upright. The absence of head movements did not influence the discriminability. These results suggest that 3-month-old infants organize the moving triangles on the face in the upright orientation into a coherent facelike structure.

Discrimination Learning↗
PubMed1986

Vitreous fluorescein accumulation determined by in vivo fluorophotometry and by vitreous extraction in normal and diabetic rats.

Vitreous fluorophotometry was performed on pigmented male rats (Piebald strain) 2 weeks after induction of diabetes by streptozotocin. In vivo fluorophotometry data were compared with measurements obtained by direct extraction of the vitreous 60 min after an intravenous injection of sodium fluorescein. In addition, the rate of fluorescein disappearance from blood plasma, plasma protein binding of fluorescein and the effect of insulin treatment of diabetic animals were investigated. Age-matched nondiabetic animals served as controls. In vivo fluorophotometric measurements showed a good correlation with fluorescein determinations after direct extraction of the vitreous. Vitreous fluorescein concentrations were similar in diabetic and normal rats and were strongly related to the dye plasma levels within each group of animals. In the diabetic rats, however, the elimination of plasma fluorescein was accelerated and the percentage of free fluorescein, as determined by ultrafiltration and equilibrium dialysis, was consistently higher (130-150% of controls). The ratios of vitreous to total or free plasma fluorescein levels were elevated in diabetic rats. Experimental data indicate that plasma concentration of free fluorescein is crucial for vitreous dye accumulation. Insulin treatment of diabetic rats markedly improved their metabolic state and normalized the plasma fluorescein elimination and the vitreous to plasma fluorescein concentration ratios. It is concluded that vitreous fluorophotometry can be adequately applied to pigmented rats, provided that plasma fluorescein elimination rate and protein binding are considered in the interpretation of the results, since both influence the vitreous fluorescein accumulation and both may be altered by disease and drug treatment.

Animals↗
PubMed1986

Kinetic contours in infants' visual perception.

3-month-old infants' perception of "camouflaged" forms that are only visible when moving was studied. Displays were used in which figure and ground had an identical random dot texture, and no edge indicated the form of the figure. The form was invisible when stationary. Discrimination of 2 different forms was tested (a) when the forms were visible only through motion, and (b) when the forms appeared as stationary white figures on black ground. The babies discriminated the forms in both conditions. Furthermore, when infants were habituated to one of the moving forms and subsequently presented with the same and a new static form, they looked longer at the new form. This indicates that they recognized the static form as either the same or different from the moving form seen before, although the optical sources of information were completely different. At 3 months, infants can therefore effectively use kinetic information to organize the visual input in higher-order structures.

Discrimination Learning↗
PubMed1985

[Our experiences with percutaneous litholapaxy].

Percutaneous litholapaxy is a non-invasive method in the surgery of kidney-stones. We prefer the one-step-proceeding--the punction, the dilatation and the intrarenal instrumentation in one session. With this method in 24 cases we have dislocated 9 pelvic-stones, 13 calix-stones and 3 upper ureteral stones which could not remove themselves. Postoperative 4 patients had small residual-stones, 2 of them removed spontaneously without colics still in time of the hospitalization. Thinking of the minimal morbidity and invasiveness we mean, we can recommend the percutaneous stone-removing to our patients with nephrolithiasis after an exact exploration in the future, too.

Adult↗
PubMed1984

Subtotal pancreatectomy in five different rat strains: incidence and course of development of diabetes.

The incidence and course of development of diabetes was studied for 12 months after subtotal pancreatectomy in five strains of rats. Operations were performed on 5-7-week old-male animals weighing 100-140 g, and, subsequently, rats with fasting blood glucose levels greater than 8.3 mmol/l were considered to be diabetic. In Füllinsdorf Albino rats, the proportion of diabetic animals gradually increased during the course of the experiment to a maximum of 83%. In Holtzman and Piebald rats, the highest incidence (58% and 28% respectively) was observed 2-3 months after surgery, after which partial remission of their diabetes occurred. Spontaneously hypertensive rats completely recovered from an initially mild diabetic state within 6 months of the operation. In Lewis rats, only a small number of animals (15%) became diabetic towards the end of the experiment. The severity of diabetes also differed considerably between strains. The pancreatic insulin content in diabetic rats was 2%-7% and in operated non-diabetic rats 17%-26% of values in non-operated control animals of the same age and strain. However, in the operated non-diabetic rats, glucose tolerance and the insulin response to glucose were also impaired. It is concluded that there are marked inter-strain differences in rats concerning the incidence and development of diabetes following subtotal pancreatectomy.

Animals↗
PubMed1982

The effect of change in a stimulus sequence on P300.

In past studies, the P300 amplitude of the ERP has been found to be enhanced for infrequent, unpredictable and/or task-relevant eliciting events. A fourth factor, namely the physical change between two consecutive stimuli in event sequences used, has often been confounded with frequency, predictability and relevance. The current study examined whether change also increases the P300 amplitude. Fourteen adults viewed sequences of slides in which predictability, task (counting) and change varied within subject. ERP was recorded at Cz, Pz, Oz and Fz. P300 amplitudes were significantly larger: (1) for unpredictable than for predictable events, (2) for counted than for non-counted stimuli, and (3) for stimulus change rather than no stimulus change. The change effect interacting with counting suggested that P300 amplitude may be particularly increased by stimulus changes imbedded within only certain cognitive tasks.

Adult↗