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K K Jensen

Publications and source records attributed to K K Jensen.

13 recordsLinked to original sources
PubMed2005

Lay and expert perceptions of zoonotic risks: understanding conflicting perspectives in the light of moral theory.

As in many other areas, there is a divide between lay and expert perceptions of risk within the food sector, and this can lead to disagreement over priorities in food risk management. The risk perception literature tends to stress that the parties involved in this disagreement have different concepts of risk and hence are bound more or less to talk at cross-purposes. This paper suggests an alternative analysis: In the light of moral theory, the conflicting perspectives can be understood as a genuine moral conflict. When this conflict is conceptualised, a rational dialogue becomes possible. The paper reports a series of qualitative interviews with lay people and experts on zoonotic food risks. The interviews are used to reconstruct the values underlying some of the dominant perspectives. The conflict between these stylised perspectives is then analysed with the help of moral theory. Finally, some consequences for risk communication are made clear.

Creutzfeldt-Jakob Syndrome↗
PubMed2001

Disruption of neutrophil migration in a conditional transgenic model: evidence for CXCR2 desensitization in vivo.

We developed transgenic mice conditionally expressing the neutrophil chemoattracting chemokine KC and the beta-galactosidase gene in multiple tissues. In these transgenic mice, doxycycline treatment induced a strong up-regulation in the expression of KC in several tissues, including heart, liver, kidney, skin, and skeletal muscle. Expression of KC within these tissues led to a rapid and substantial increase in the serum levels of KC (serum KC levels were higher than 200 ng/ml 24 h after treatment). Accordingly, beta-galactosidase expression was also detected after injection of doxycycline and was highest in skeletal muscle, pancreas, and liver. Surprisingly, despite expression of KC in multiple tissues, no neutrophil infiltration was observed in any of the tissues examined, including skin. Doxycycline treatment of nontransgenic mice grafted with transgenic skin caused dense neutrophilic infiltration of the grafts, but not the surrounding host skin, indicating that the KC produced in transgenic tissues was biologically active. In separate experiments, neutrophil migration toward a localized source of recombinant KC was impaired in animals overexpressing KC but was normal in response to other neutrophil chemoattractants. Analysis of transgenic neutrophils revealed that high concentrations of KC in transgenic blood had no influence on L-selectin cell surface expression but caused desensitization of the receptor for KC, CXCR2. These results confirm the neutrophil chemoattractant properties of KC and provide a mechanistic explanation for the paradoxical lack of leukocyte infiltration observed in the presence of elevated concentrations of this chemokine.

Animals↗
PubMed2001

Enhanced fluorescence resonance energy transfer between spectral variants of green fluorescent protein through zinc-site engineering.

Although spectral variants of GFP should in theory be suited for fluorescence resonance energy transfer (FRET) and therefore suited for studies of protein-protein interactions, the unfavorable location of the fluorophore 15 A deep inside the GFP molecule has especially impaired this application. Here, metal-ion site engineering around the dimerization interface known from the X-ray structure of GFP is applied to the cyan and the yellow spectral variant of GFP to stabilize the heterodimeric form of these molecules and thereby increase FRET signaling. The FRET signal, determined as the ratio between the maximal emission for the yellow variant, 530 nm, and the cyan variant, 475 nm, during excitation of the cyan variant at 433 nm was increased up to 8-10-fold in the presence of 10(-4) M ZnCl2 by engineering of two symmetric metal-ion sites being either bidentate or tridentate. A similar increase in FRET signaling was however obtained in a pair of molecules in which a single bidentate metal-ion site was generated by introducing a zinc-binding residue in each of the two spectral variants of GFP and therefore creating an obligate heterodimeric pair. It is concluded that FRET signaling between spectral variants of GFP can be increased by stabilizing dimer formation and especially by favoring heterodimer formation in this case performed by metal-ion site engineering.

Amino Acid Sequence↗
PubMed1997

Kinetics for hybridization of peptide nucleic acids (PNA) with DNA and RNA studied with the BIAcore technique.

The binding of a mixed-sequence pentadecamer PNA (peptide nucleic acid) containing all four nucleobases to the fully complementary as well as various singly mismatched RNA and DNA oligonucleotides has been systematically investigated using thermal denaturation and BIAcore surface-interaction techniques. The rate constants for association (k(a)) and dissociation (k(d)) of the duplex formation as well as the thermal stability (melting temperature, T(m)) of the duplexes have been determined. Upon binding to PNA tethered via a biotin-linker to streptavidin at the dextran/gold surface, DNA and RNA sequences containing single mismatches at various positions in the center resulted in increased dissociation and decreased association rate constants. T(m) values for PNA x RNA duplexes are on average 4 degrees C higher than for PNA x DNA duplexes and follow quantitatively the same variation with mismatches as do the PNA x DNA duplexes. Also a faster k(a) and a slower k(d) are found for PNA x RNA duplexes compared to the PNA x DNA duplexes. An overall fair correlation between T(m), k(a), and k(d) is found for a series of PNA x DNA and PNA x RNA duplexes although the determination of k(a) seemed to be prone to artifacts of the method and was not considered capable of providing absolute values representing the association rate constant in bulk solution.

Biosensing Techniques↗
PubMed1995

[Image transmission between hospitals. Technical and clinical testing of the equipment for digital image transmission between hospitals via the ordinary telephone network].

A standard PC-based equipment--"Multiview Photophone"--for two-way image conference between hospitals by means of digital images transmitted through ordinary telephone lines was tested. The technical and visual quality of scanned and transmitted pictures proved to be satisfactory, and ease of handling the equipment and transmission times were acceptable. The clinical test was made by image conferences between a neurological department in a general hospital and a neurosurgical department in a university hospital. CT-scans concerning 39 patients in a prospective series, for whom specialist advice from the neurosurgical department was found necessary, were transmitted. Four of nine acute patients were saved an "unnecessary" transferral to the neurosurgical department. The 30 elective patients were all found to benefit from the two-way conferences, since the decision time was reduced and the quality of information given to the patients and their relatives was improved.

Computer Communication Networks↗
PubMed1993

Bacillus subtilis transcription regulator, Spo0A, decreases alkaline phosphatase levels induced by phosphate starvation.

Alkaline phosphatase (APase) is induced as a culture enters stationary phase because of limiting phosphate. The results presented here show that expression of APase is regulated both negatively and positively. PhoP, a homolog of a family of bacterial transcription factors, and PhoR, a homolog of bacterial histidine protein kinases, are required for induction of APases when phosphate becomes limiting. The induction period lasts 2 to 3 h, after which the rate of APase accumulation is decreased. Mutant strains defective in the Spo0A transcription factor failed to decrease APase production. The consequent hyperinduction of APase in a spo0A strain was dependent on phoP and phoR. spo0B and spo0F strains also overexpressed APase, suggesting that phosphorylated Spo0A is required for repression of APase. An abrB mutant allele in the presence of the mutant spo0A allele in these strains did not significantly change the APase hyperinduction phenotype, demonstrating that Spo0A repression of abrB expression is not the mechanism by which Spo0A-P regulates APase expression. Our previous report that spo0A mutants do not express APases is in conflict with the present data. We show here that the previously used mutants and a number of commonly used spo0 strains, all of which have an APase deficiency phenotype, contain a previously unrecognized mutation in phoR.

Alkaline Phosphatase↗
PubMed1989

Protoplast transformation of Bacillus licheniformis MC14.

A protoplast transformation system has been developed for Bacillus licheniformis MC14. Optimum regeneration conditions were achieved by raising the incubation temperature of the regeneration plates to 46 degrees C. Regenerated transformed colonies could be isolated in 3 to 5 d under these conditions. Plasmids introduced by this method were stably maintained by B. licheniformis MC14 and could be recovered and used to transform Bacillus subtilis.

Bacillus↗
PubMed1982

Role of delayed gastric emptying in the pathogenesis of cysteamine-induced duodenal ulcer in the rat.

Cysteamine is a potent duodenal ulcerogen in rats. It has been demonstrated to inhibit gastric empyting, whose role in ulcer formation is unknown. In the present study the effect of cysteamine on gastric motility and emptying rate in rats was studied by direct fluoroscopic observation. The delayed gastric empyting was due to a pronounced relaxation of the stomach and a complete blocking of gastric peristalsis. These effects have their maximum within the first 4 h after administration of cysteamine. Thereafter peristalsis and gastric empyting slowly return. In controls contrast medium administered intragastrically was completely discharged from the stomach within 30 min. After cysteamine the first small amounts of contrast medium were discharged into the duodenum after 4 h, and contrast medium remained in the stomach for at least 12 h after administration. The size of the stomach reached a maximum after 3 h and approached normal values again after 12 h. Because of complete gastric retention the acid gastric secretions provoked by cysteamine probably accumulate in the stomach during the first 4 h after cysteamine administration, and because of the absence of peristalsis they are not mixed with gastric contents. After 4 h this pool of undiluted gastric secretions gradually is emptied into the duodenum, where the mucosal resistance is reduced by inhibition of the secretory activity of Brunner's glands, and ulceration rapidly develops. The time relationship is supported by histopathologic findings and measurements of gastric acid secretions after cysteamine. Vagotomy augmented the inhibitory effect of cysteamine on gastric motility. The relaxation was even more pronounced, and contrast medium was not discharged from the stomach within 24 h. In these rats cysteamine induced ulcerations in the stomach.

Animals↗
PubMed1981

Inhibition of Escherichia coli by thioglycerol.

Thioglycerol inhibits the growth of various Escherichia coli strains and other microorganisms, both gram positive and gram negative. The susceptibility of organisms varies. The bactericidal action of this substance is not continuous and stops after an initial burst. At subbactericidal concentrations synthesis of ribonucleic acid is the most strongly affected. This is not due to interference with nucleoside biosynthesis or to direct inhibition of ribonucleic acid polymerase by thioglycerol.

Bacterial Proteins↗