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H Keller

Publications and source records attributed to H Keller.

At least 145 records · Page 8Linked to original sources
PubMed1993

A pathogen-responsive gene of parsley encodes tyrosine decarboxylase.

A group of recently isolated parsley (Petroselinum crispum) cDNAs representing genes that are transcriptionally activated upon fungal infection or elicitor treatment have been demonstrated to encode tyrosine decarboxylase (TyrDC). The deduced TyrDC protein sequence shares extensive similarity with two functionally related enzymes, tryptophan decarboxylase from periwinkle and dopa decarboxylase from Drosophila melanogaster. Expression of TyrDC cDNA in Escherichia coli yielded catalytically active protein with high substrate specificity for tyrosine. All four identified parsley TyrDC genes have been cloned and encode at least three TyrDC isozymes. Treatment of cultured parsley cells with fungal elicitor caused very rapid and transient increases in TyrDC mRNA and enzyme activity levels.

Amino Acid Sequence↗
PubMed1993

Inhibition of chemotactic peptide-induced development of cell polarity and locomotion by the protein kinase C inhibitor CGP 41 251 in human neutrophils correlates with inhibition of protein phosphorylation.

Several protein kinase inhibitors of the staurosporine type displaying different enzyme specificity were used to study the role of protein kinase C (PKC) in motile neutrophil functions. Effects on protein phosphorylation, F-actin localization, morphology, and locomotion were determined. Only staurosporine, but not another inhibitor more specific for PKC (CGP 41 251) or inhibitors of cyclic nucleotide-dependent kinases (KT 5720, KT 5822), induced formation of F-actin-enriched surface protrusions at nanomolar concentrations in initially spherical neutrophils. The inhibitor with the highest specificity for PKC, CGP 41 251, had no effect on morphology and F-actin localization of resting cells up to 1 microM. However, this inhibitor suppressed front-tail polarity and locomotion in chemotactic peptide-stimulated cells. The cells became nonpolar with surface projections instead. Inhibition of front-tail polarity induced by CGP 41 251 strongly correlated with inhibition of in situ phosphorylation of a 67-kDa protein (IC50 = 0.2 microM), whereas induction of polarity by chemotactic peptide was associated with increased phosphorylation of this protein. Kinase inhibitors inactive on PKC (KT 5720, KT 5822) did not affect development of front-tail polarity. We conclude that a kinase involved in the phosphorylation of a 67-kDa protein, very likely a PKC isoform, may be important for the development of cell polarity and locomotion. In contrast, chemotactic peptide-induced formation of actin-containing protrusions may not be mediated by this enzyme.

Actins↗
PubMed1993

Xenopus peroxisome proliferator activated receptors: genomic organization, response element recognition, heterodimer formation with retinoid X receptor and activation by fatty acids.

Peroxisome proliferator activated receptors are ligand activated transcription factors belonging to the nuclear hormone receptor superfamily. Three cDNAs encoding such receptors have been isolated from Xenopus laevis (xPPAR alpha, beta, and gamma). Furthermore, the gene coding for xPPAR beta has been cloned, thus being the first member of this subfamily whose genomic organization has been solved. Functionally, xPPAR alpha as well as its mouse and rat homologs are thought to play an important role in lipid metabolism due to their ability to activate transcription of a reporter gene through the promoter of the acyl-CoA oxidase (ACO) gene. ACO catalyzes the rate limiting step in the peroxisomal beta-oxidation of fatty acids. Activation is achieved by the binding of xPPAR alpha on a regulatory element (DR1) found in the promoter region of this gene, xPPAR beta and gamma are also able to recognize the same type of element and are, as PPAR alpha, able to form heterodimers with retinoid X receptor. All three xPPARs appear to be activated by synthetic peroxisome proliferators as well as by naturally occurring fatty acids, suggesting that a common mode of action exists for all the members of this subfamily of nuclear hormone receptors.

Acyl-CoA Oxidase↗
PubMed1993

Positive regulation of the peroxisomal beta-oxidation pathway by fatty acids through activation of peroxisome proliferator-activated receptors (PPAR).

Peroxisome proliferators regulate the transcription of genes by activating ligand-dependent transcription factors, which, due to their structure and function, can be assigned to the superfamily of nuclear hormone receptors. Three such peroxisome proliferator-activated receptors (PPAR alpha, beta, and gamma) have been cloned in Xenopus laevis. Their mRNAs are expressed differentially; xPPAR alpha and beta but not xPPAR gamma are expressed in oocytes and embryos. In the adult, expression of xPPAR alpha and beta appears to be ubiquitous, and xPPAR gamma is mainly observed in adipose tissue and kidney. Immunocytochemical analysis revealed that PPARs are nuclear proteins, and that their cytoplasmic-nuclear translocation is independent of exogenous activators. A target gene of PPARs is the gene encoding acyl-CoA oxidase (ACO), which catalyzes the rate-limiting step in the peroxisomal beta-oxidation of fatty acids. A peroxisome proliferator response element (PPRE), to which PPARs bind, has been identified within the promoter of the ACO gene. Besides the known xenobiotic activators of PPARs, such as hypolipidemic drugs, natural activators have been identified. Polyunsaturated fatty acids at physiological concentrations are efficient activators of PPARs, and 5,8,11,14-eicosatetraynoic acid (ETYA), which is the alkyne homolog of arachidonic acid, is the most potent activator of xPPAR alpha described to date. Taken together, our data suggest that PPARs have an important role in lipid metabolism.

Acyl-CoA Oxidase↗
PubMed1993

The effect of endotoxin and tumour necrosis factor on erythrocyte and leucocyte deformability in vitro.

Microcirculatory disorders are a common finding in sepsis. We have analysed the influence of two factors released in sepsis, endotoxin and tumour necrosis factor (TNF), on rheological properties of blood cells. The deformability of mixed cell suspensions, isolated erythrocytes, mononuclear cells, or polymorphonuclear leucocytes exposed to endotoxin and TNF in vitro was assessed by filtration through pores of different sizes. Mixed blood cell suspensions showed an increase in cell rigidity when incubated with 100 ng/ml endotoxin. The filtration resistance of isolated erythrocytes, mononuclear or polymorphonuclear leucocytes was not affected by endotoxin. Incubation with TNF in physiological concentrations increased the rigidity of mixed blood cells and of isolated polymorphonuclear leucocytes in a dose- and time-dependent manner, while erythrocytes and mononuclear leucocytes remained unaffected. Polymorphonuclear cells showed decreased deformability associated with shape changes (polarized and non-polar cells with surface protrusions and a shift of F-actin into protrusions). The decrease in deformability was reversed by cytochalasin B or xanthin derivatives such as pentoxifylline. We conclude that TNF decreases the passive deformability of polymorphonuclear leucocytes, which may affect the microcirculation in sepsis. The reversibility with xanthin derivatives may represent a new therapeutic approach for the high morbidity and mortality in sepsis.

Endotoxins↗
PubMed1993

Disposition, bioavailability and clinical efficacy of orally administered acepromazine in the horse.

The pharmacokinetics and pharmacological efficacy of orally (p.o.) administered acepromazine were studied and compared with the intravenous (i.v.) route of administration in a cross-over study using six horses. The oral kinetics of acepromazine can be described by a two-compartment open model with first-order absorption. The drug was rapidly absorbed after p.o. administration with a half-life of 0.84 h, tmax of 0.4 h and Cmax of 59 ng/ml. The elimination was slower after p.o. administration (half-life 6.04 h) than after i.v. injection (half-life 2.6 h). The bioavailability of the orally administered drug formulation was 55.1%. After p.o. administration of 0.5 mg/kg acepromazine, the parameters of the sedative effect were similar to those obtained after i.v. injection of 0.1 mg/kg. The effect of the drug on blood cell count and haemoglobin content was similar after both p.o. administration and injection, while the effects on the parameters of penile prolapse and on the mean arterial blood pressure were less pronounced after p.o. administration than after injection. After p.o. administration, no significant effects on haematocrit-level as well as on the heart and respiratory rates were observed, while these parameters were significantly affected after injection. It is concluded that the high initial plasma level of the drug after i.v. injection may play a role in producing adverse effects of acepromazine.

Absorption↗
PubMed1993

A new look at the limits of detection (LD), quantification (LQ) and power of definition (PD)

The relationship between the concentration of the analyte and the imprecision of an analytical method can be displayed by the precision profile in which the coefficient of variation (relative standard deviation) is plotted against the concentration of the analyte. The function of the curve of the profile and its confidence limits can easily be assessed by a computer program developed by W.A. Sadler & M.H. Smith (Clin. Chem. 36 (1990), 1346-1350). For the assessment of limits of detection and of quantification the following procedure is proposed: The lower (and upper) limit of the measuring interval is defined by the point at which an acceptable CV-line intersects the confidence limit. If, in the variance function one sets the concentration to zero, the normal distribution of the random errors of the blank will result. The mean of the next adjacent normal distribution, following the variance formula and overlapping the "zero-distribution" by a defined amount, represents the limit of detection. Within the described measuring interval, or within a fraction of it, one might construct overlapping normal distributions in an analogous manner. Their number represents the "power of definition" (PD) (instead of the "analytical sensitivity"), which also depends on the concentration of the determinand according to the variance function. We tested these hypotheses by a comparison of two methods for the determination of cyclosporin A (ciclosporin, INN). Our results demonstrate that the data of the lower limits of the measuring interval and of the limit of detection agree well with data from the literature obtained in extensive interlaboratory surveys.

Algorithms↗
PubMed1993

[The value of colon contrast enema in ileus diagnosis].

In 115 patients with clinical and radiological signs of small and/or large bowel obstruction the contrast enema of the colon was evaluated prospectively to localize the site of occlusion in the colon. Contrast enema was performed in 76 patients with Gastrografin and in 39 with barium. In 22 of 24 patients with large bowel obstruction, in 7 of 11 with combined small and large bowel obstruction, in 4 of 14 with small bowel obstruction and in 19 of 66 with partial obstruction the site of obstruction was identified in the colon. In 107 of 115 patients the site of intestinal obstruction in the colon was either confirmed or excluded (sensitivity 89.2%, specificity 96.6%). In 6 patients the contrast enema failed due to incontinence, missing cooperation or insufficient preparation. In two cases with coprostasis the occlusion was missinterpreted as a carcinoma. Electrolytes and serum fluid concentration before and after the enema were not significantly influenced using the different contrast media. Contrast enema is indicated in patients with intestinal obstruction of unknown site, malignancies, after radiation therapy and recurrent partial obstruction.

Adolescent↗
PubMed1993

[30 years of the Swine Health Service].

The establishment of a Porcine Health Service (PHS) was pioneered in the early sixties. After reviewing the history of the formation of the PHS, a few examples of how it stimulated research in several fields in our two faculties are given. The development of the PHS was noticeably slowed down by yearly recurrent "mysterious" outbreaks of actinobacillosis and especially enzootic pneumonia. Epidemiologic investigations have since shown that the reintroductions of these pathogens can occur by airborne transmission. This information filled the last important gap in the battle against these economically and public health important diseases. Simultaneously it became apparent that enzootic pneumonia and actinobacillosis are not merely herd problems but epizootics which can only be eradicated by means of modern disease control legislation. The question is posed whether or not the PHS, which is potentially a valuable tool in the hands of the state veterinarians, should continue to remain under the control of the producers.

Animals↗
PubMed1993

[The gamma nail--an ideal implant for treatment of unstable fractures in elderly patients].

Altogether we used the Gamma-Nail in 150 cases. We show here a series of 50 instable pertrochanteric femur fractures in very old patients which we treated with a Gamma-Nail. All cases started with full weight bearing at the 4th day after operation. A clinical and radiological control 12 weeks later shows good mobilisation of the hip in 70% of the cases. Shortening of the operated leg is rare in comparison of cases treated with a DHS. Two thirds of the patients returned after dismission of the hospital to the old social situation. The advantages in treating instable pertrochanteric femur fractures with the Gamma-Nail are immediate full weight bearing without risks of shortening of the operated leg and the closed reduction of the fracture.

Aged↗
PubMed1993

[Stable interlocking intramedullary nailing of humeral fractures with the Seidel nail].

22 fractures of the humerus (15 traumatological, 7 pathological) were treated with the Seidel-Nail. The results after a follow-up between 4 and 20 months showed good mobility of the shoulder. As major complications two paresis of the radial nerve occurred. One disappeared spontaneously. The Seidel-Nail is a good implant for all kind of shaft fractures with an intact distal fragment of 5 cm and also for fractures of an intact humerus head.

Aged↗
PubMed1993

Developmental consequences of early eye contact behaviour.

Through early interactional exchange, infants acquire relevant information about themselves, their caretaking persons, and the relationship between themselves and their caretakers. Mutual eye contact is a highly adaptive behavioural system in this respect. There are, however, infants who avoid maternal eye contact and refuse their caretakers' attention. Gaze aversion of this kind is only reported to occur in the first months of life. It is interpreted as a first manifestation of a specific interaction. The present longitudinal study presents evidence for developmental consequences of early eye contact patterns. Infants who avert their gaze from their parents in the first months of life develop maladaptive relationships in terms of interactional harmony within 2 years, low degrees of psychobiological functioning, behavioural problems, and developmental delays for up to 6 years, and, at 2 years of age, explore new objects by means of manipulation for only short amounts of time. Infants with the expected good eye contact behaviour at that early age appear to have a more favourable development during the preschool years.

Adaptation, Psychological↗
PubMed1992

Risk factors for the reinfection of specific pathogen-free pig breeding herds with enzootic pneumonia.

A case control study was designed to determine the risk factors for the reinfection of Swiss specific pathogen-free (SPF) pig herds with enzootic pneumonia. Detailed housing, management and environmental data were collected from 42 case farms and 50 control farms by means of a questionnaire. Factors with a significantly asymmetrical frequency distribution among the two groups were considered to be possibly associated with reinfection; they included the distance to the nearest non-SPF pig herd, the size of that herd, the density of the pig population in the area, the distance to the next road regularly carrying pig transporters and differences in topography. The results tended to support the hypothesis of the airborne transmission of enzootic pneumonia. Using a formula considering the main risk factors, it was possible to classify farms as high or low risk with an 84 per cent specificity and 74 per cent sensitivity.

Air Pollution↗
PubMed1992

Protein phosphatase inhibitors okadaic acid and calyculin A alter cell shape and F-actin distribution and inhibit stimulus-dependent increases in cytoskeletal actin of human neutrophils.

The phosphatase inhibitors okadaic acid and calyculin A were found to elicit or to modify several neutrophil responses, suggesting that dephosphorylation plays a regulatory role. The concentrations of okadaic acid (> or = 1 mumol/L) that were effective on neutrophil functions (shape changes and marginal stimulation of pinocytosis) were shown to stimulate the incorporation of 32PO4 into many neutrophil proteins several-fold. Calyculin A was effective at 50-fold lower concentrations. In the presence of the inhibitors, the cells exhibited a nonpolar shape and the polarization response induced by chemotactic peptide was inhibited. Both phosphatase inhibitors also induced the association of F-actin with the cell membrane. A steady-state phosphatase activity is thus involved in maintaining shape and F-actin localization of resting cells. Inhibitors alone had no significant effect on the amount of cytoskeleton-associated actin. The increase in cytoskeletal actin observed at 30 minutes of stimulation with phorbol ester or 5 to 30 minutes of stimulation with chemotactic peptide, however, was abolished by okadaic acid or calyculin A, suggesting an important role of a phosphatase. In contrast, the early increase in cytoskeleton-associated actin observed at 1 minute of stimulation with peptide was not affected. This finding indicates that the increased association of actin with the cytoskeleton in the early and the later stages of neutrophil activation may be mediated by different signalling pathways.

Actins↗