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Biomedical subjects

A B Christensen

Publications and source records attributed to A B Christensen.

At least 19 recordsLinked to original sources
PubMed2001

Methods for detecting acylated homoserine lactones produced by Gram-negative bacteria and their application in studies of AHL-production kinetics.

In the process of evaluating the role of acylated homoserine lactones (AHLs) in food-spoiling Gram-negative bacteria, we have combined a range of bacterial AHL monitor systems to determine the AHL-profile and the kinetics of AHL-production. AHL production from 148 strains of Enterobacteriaceae isolated from foods was tested using Escherichia coli pSB403 (LuxR), Agrobacterium tumefaciens A136 (TraR) and both induction and inhibition of Chromobacterium violaceum CV026 (CviR). All strains except one was found to produce AHL(s). In no case could a single monitor system identify more than 64% of the Enterobacteriaceae as AHL-producers, showing that the simultaneous use of monitor strains is required in the process of screening bacterial populations for AHL-production. AHLs from 20 selected strains were profiled by thin layer chromatography. Most strains produced more than one AHL with 3-N-oxo-hexanoyl homoserine lactone being the most prominent. It was found that the simultaneous use of monitor strains in the top-layer was necessary for the detection of (presumably) all the AHLs. An agar well-diffusion assay based on A. tumefaciens pDZLR4 was used for quantifying AHLs from bacterial supernatants and enabled an assessment of the kinetics of AHL-production of 3 strains (Serratia proteamaculans strain B5a, Erwinia carotovora ATCC 39048 and V. fischeri strain MJ-1). As expected, the production of AHL (OHHL) and luminescence in Vibrio fischeri strain MJ-1 increased faster than growth indicating up-regulation of the AHL regulated phenotype and auto-induction of AHL production. In contrast, production kinetics of AHL (OHHL) in the two Enterobacteriaceae indicated lack of auto-induction.

4-Butyrolactone↗
PubMed2000

Respiration in the burrowing brittlestar, Hemipholis elongata say (Echinodermata, Ophiuroidea): a study of the effects of environmental variables on oxygen uptake.

The burrowing brittlestar Hemipholis elongata (Say) maintains a constant M(O2)of 3.79+/-1.47 micromol O(2) g(-1) h(-1) (for 0.2-0.3 g animals, mean+/-S.D., n=7), measured in the burrow, over a broad range of PO(2). Below the critical PO(2) of 37 mm Hg, M(O(2)) becomes dependent on the oxygen tension. M(O2) is a function of the size of H. elongata; the scaling exponent is 0. 83 and is similar to those reported for other echinoderms. The M(O2) of H. elongata is unaffected by removal from the burrow, by hypercapnia, by exposure to hydrogen sulfide, or by temperature change in the range from 20 to 32 degrees C. The relative insensitivity of H. elongata to these factors may be an adaptation to life in the highly variable estuarine and tidal creek environments where the animals are frequently found.

Animals↗
PubMed2000

A prospective, controlled, randomized study of the effect of a slow-release silver device on the frequency of urinary tract infection in newly catheterized patients.

OBJECTIVE: To test the effect on urinary tract infections (UTIs) in patients needing continuous indwelling catheterization, of a newly designed urine-collecting system containing an antibacterial device which slowly releases silver ions onto the inner surface of the system. PATIENTS AND METHODS: The study comprised a prospective controlled randomized trial; 213 patients fulfilled the inclusion criteria. They were randomized to a urine drainage system (comprising a Unometer 400 metering system or PP 2000N closed urine-bag system, both from Maersk Medical, Denmark) either with or without the antibacterial device. The efficacy was assessed as the number of UTIs and the time to infection in the 170 patients eligible for analysis. RESULTS: There were fewer UTIs in those using the system containing the antibacterial device (19% vs 24%), but the difference was not statistically significant (P < 0.05). CONCLUSION: The potential importance of different infection routes were highlighted, suggesting that modifications to Foley catheters and urine-collecting systems attempting to prevent UTIs should focus not only on the intraluminal pathway, but on the internal and external pathways of infection.

Adult↗
PubMed2000

Assessment of flhDC mRNA levels in Serratia liquefaciens swarm cells.

We reported previously that artificial overexpression of the flhDC operon in liquid-grown Serratia liquefaciens resulted in the formation of filamentous, multinucleated, and hyperflagellated cells that were indistinguishable from surface-induced swarm cells (L. Eberl, G. Christiansen, S. Molin, and M. Givskov, J. Bacteriol. 178:554-559, 1996). In the present report we show by means of reporter gene measurements, Northern analysis, and in situ reverse transcription-PCR that the amount of flhDC mRNA in surface-grown swarm cells does not exceed the maximum level found in nondifferentiated, vegetative cells. This suggests that surface-induced S. liquefaciens swarm cell differentiation, although dependent on flhDC gene expression, does not occur through elevated flhDC mRNA levels.

Bacterial Proteins↗
PubMed1999

Production of acylated homoserine lactones by psychrotrophic members of the Enterobacteriaceae isolated from foods.

Bacteria are able to communicate and gene regulation can be mediated through the production of acylated homoserine lactone (AHL) signal molecules. These signals play important roles in several pathogenic and symbiotic bacteria. The following study was undertaken to investigate whether AHLs are produced by bacteria found in food at temperatures and NaCl conditions commercially used for food preservation and storage. A minimum of 116 of 154 psychrotrophic Enterobacteriaceae strains isolated from cold-smoked salmon or vacuum-packed chilled meat produced AHLs. Analysis by thin-layer chromatography indicated that N-3-oxo-hexanoyl homoserine lactone was the major AHL of several of the strains isolated from cold-smoked salmon and meat. AHL-positive strains cultured at 5 degrees C in medium supplemented with 4% NaCl produced detectable amounts of AHL(s) at cell densities of 10(6) CFU/ml. AHLs were detected in cold-smoked salmon inoculated with strains of Enterobacteriaceae stored at 5 degrees C under an N(2) atmosphere when mean cell densities increased to 10(6) CFU/g and above. Similarly, AHLs were detected in uninoculated samples of commercially produced cold-smoked salmon when the level of indigenous Enterobacteriaceae reached 10(6) CFU/g. This level of Enterobacteriaceae is often found in lightly preserved foods, and AHL-mediated gene regulation may play a role in bacteria associated with food spoilage or food toxicity.

Animals↗
PubMed1998

A flavonoid 7-O-methyltransferase is expressed in barley leaves in response to pathogen attack.

We have shown previously that transcripts corresponding to the cDNA clone pBH72-F1, with similarities to O-methyltransferases (OMT), accumulated in barley leaves in response to attack by the pathogenic fungus Blumeria graminis (Plant Mol Biol 26 (1994) 1797). To investigate the accumulation pattern in the defence response and the organ localization of the pBH72-F1-encoded polypeptide (F1-OMT), an antiserum was raised against Escherichia coli expressed F1-OMT. The 43 kDa protein was absent in normal leaves but accumulated strongly in response to pathogen attack. The F1-OMT protein accumulated faster in barley lines inoculated with an avirulent B. graminis isolates compared to a virulent isolate. Additionally, F1-OMT related proteins were detected in developing kernels. F1-OMT was expressed as a functional enzyme in E. coli and the substrate specificity was investigated. The enzyme exhibited OMT activity towards flavonoid aglycones with the highest activity against apigenin (4',5,7-trihydroxyflavone). In contrast, caffeic acid did not serve as substrate for F1-OMT. The product of F1-OMT was analyzed by HPLC and GC-MS and found to be genkwanin (4',5-dihydroxy-7-methoxyflavone). Initial velocity data were best represented by a sequential bi-bi mechanism, and kinetic parameters of KSAM = 10.9 microM, Kapigenin = 4.6 microM and a specific activity of 0.45 mukat/g were obtained. Barley F1-OMT, apigenin 7-O-methyltransferase, is suggested to be involved in the production of a methylated flavonoid phytoalexin.

Ascomycota↗
PubMed1998

A chalcone synthase with an unusual substrate preference is expressed in barley leaves in response to UV light and pathogen attack.

A cDNA clone was isolated by differential hybridization from a library prepared from barley leaves inoculated with the fungus Blumeria graminis f.sp. hordei (Bgh). The open reading frame of the insert (designated HvCHS2) encoded a polypeptide with 72-79% identity to chalcone synthases (CHS) and 65-68% identity to stilbene synthases. Alignments of the amino acid sequence of HvCHS2 with the consensus sequence of naringenin-CHS (EC 2.3.1.74) reveals significant differences between HvCHS2 and naringenin-CHS. HvCHS2 transcripts accumulate strongly in barley leaves in response to inoculation with Bgh, whereas only insignificant accumulation of barley naringenin-CHS (CHS1) transcripts is seen upon the inoculation. The accumulation of HvCHS2 transcripts is also elicited by UV light. To compare the activity of HvCHS2 with the activity of CHS1, the two enzymes were expressed in Escherichia coli. Both HvCHS2 and CHS1 catalyse the formation of chalcones. However, HvCHS2 and CHS1 differ in their substrate requirements. CHS1 uses cinnamoyl-CoA and 4-coumaroyl-CoA at comparable rates whereas feruloyl-CoA is a poor substrate for this enzyme. In contrast, HvCHS2 converts feruloyl-CoA and caffeoyl-CoA at the highest rate whereas cinnamoyl-CoA is a poor substrate. Thus, HvCHS2 is a novel pathogen and UV light induces homoeriodictyol/eriodictyol CHS involved in the direct production of flavonoids possessing multi-substituted B-rings.

Acyl Coenzyme A↗
PubMed1997

[Community psychiatric treatment and needs of admission of psychiatric patients. A controlled study 5 years after introduction of a community psychiatric center].

The utilization of the psychiatric in-patient services was evaluated in the intervention district and compared with a selected control district. The number of admissions and in-patient days were similar before admission to the community psychiatric service. As a result of the intervention the number of admissions to hospital and the length of in-patient hospital stay decreased significantly, resulting in a reduction of total number of in-patient days by 47%. The findings of other recent studies follow the same pattern. The reduction in in-patient days was significant in the group of schizophrenic patients.

Adult↗
PubMed1994

[Therapeutic need of acute psychiatric patients and offered care during a 10-year period].

With reference to the great changes made in recent years within the Danish psychiatric services, we compared the demand for care of acute psychiatric patients with the care offered. Over a period of three months in 1991 we prospectively registered all 243 acute psychiatric referrals to Svendborg Hospital, with regard to age, sex, way and source of referral, diagnosis, need for care and care offered. The result was compared with similar surveys in 1980 and 1985. We found that optimal treatment was not available to approximately 20% of the acute psychiatric referrals, the care we most often were unable to offer was acute admission to the psychiatric ward of Svendborg Hospital. We also found that from 1980 to 1991 there were no changes in the number of daily referrals, in the sex ratio or the age distribution of the patients. Our ability to meet the specific needs for care changes quantitatively throughout the period. The survey concludes that we are still unable to meet the specific needs for treatment of acute psychiatric referrals. Various suggestions are made as to how to improve the services offered to acute psychiatric patients.

Acute Disease↗
PubMed1994

A putative O-methyltransferase from barley is induced by fungal pathogens and UV light.

A cDNA clone, pBH72-F1 (F1), was isolated from a cDNA library prepared from barley leaves 72 h after inoculation with Erysiphe graminis f.sp. hordei. The 1388 bp nucleotide sequence of pBH72-F1 contains an open reading frame encoding a 42.3 kDa polypeptide of 390 amino acids which shows sequence similarity to O-methyltransferases (OMTs) from different plant species; the highest identity (41%) was observed with a putative OMT expressed in roots of maize. A phylogenetic analysis shows that the barley and maize sequences are distinctly different from the ortho-diphenol-OMTs involved in lignin formation. A putative S-adenosyl-L-methionine-binding motif (KELVDDSITN) determined for a rabbit protein-carboxyl OMT is partially conserved in the encoded amino acid sequence. Genomic Southern blot hybridization shows that pBH72-F1 probably represents a single copy gene. The F1 clone corresponds to a gene transcript exhibiting a relatively late accumulation in mildew-infected barley leaves compared to other pathogen-induced transcripts, such as transcripts encoding PR proteins, a peroxidase, and transcripts homologous to a maize caffeic acid OMT. No transcript was detected in plants exhibiting papilla resistance at time points when resistance is thought to be manifested. The atypical transcript accumulation pattern for F1 was also observed after infection by other pathogens and after UV-light treatment.

Amino Acid Sequence↗
PubMed1992

[In-hospital day for patients connected with the District Psychiatric Center in Svendborg. A controlled study].

As of 31.12.1990, the employment of bed-days and admissions was calculated for patients who had been connected with a district psychiatric centre for more than three years. A before-and-after comparison revealed a percentage reduction in the employment of bed-days as compared with a control group. This corresponds to the findings in other investigations. In the before-and-after analysis, various reductions are described according to the diagnostic groups. The reduction in bed-day employment consisted mainly of fewer readmissions and reduction in the group of long-term hospitalisations. A reduction also occurred in the group of patients who could characterized as least ill. In this group, a marked percentage reduction in bed-days was observed as compared with the control group and this was probably due to the good and continuous treatment after discharge offered by the district psychiatric centre. This investigation revealed that the employment of bed-days for a patient population receiving district psychiatric treatment after discharge can be reduced. Nevertheless, the most severely ill patients will still require periodic admission to hospital. The value of treatment after discharge of the "Svendborg Model" type does not provide scientifically valid arguments that hospital admission can be avoided where the most severely ill patients are concerned.

Adult↗
PubMed1992

[Psychiatric diseases among the homeless in Funen County].

The purpose of the study was to investigate whether deinstitutionalization of psychiatric patients had produced a clientele of homeless mentally ill people which is not treated. During week 47, 1990, 94 of the 129 residents 73%) in the institutions for homeless people in the County of Funen (population 459,000) were examined for mental illness by a psychiatrist. Diagnoses were made using the ICD-8 classification. Social data were recorded. Eighty-nine per cent were men, 59% were aged 30-49 years, 93% were single, and source of incomes for 80% were public assistance or disability pensions. More than half had been sentenced for crime at least once. The majority suffered from severe psychosocial strain. In 91% a psychiatric diagnosis was established, the most frequent being alcoholism (73%) and personality or character disorder (70%). Psychoses were found in 10 cases or 11%. About 29% required psychiatric treatment. The conclusion was that deinstitutionalization in the County of Funen had not resulted in influx of psychotic persons to institutions for the homeless people.

Adult↗
PubMed1991

Long-term results of bladder neck incision in men.

A retrospective cohort of 163 male patients having either uni- (UI) or bilateral incision (BI) of the bladder neck to relieve infravesical obstruction was reviewed. Short-term results were excellent with significant improvement of flow rates. 82% (UI) and 87% (BI) of the incised patients were satisfied. Long-term results were assessed by a life-table analysis. 17% (UI) and 12% (BI) of the patients needed a reoperation during the observation period of 6 years. It is concluded that bladder neck incision is a method with few complications and favourable long-term results.

Adult↗
PubMed1988

Gastrointestinal permeability to polyethylene glycol: an evaluation of urinary recovery of an oral load of polyethylene glycol as a parameter of intestinal permeability in man.

The permeability of the gastrointestinal tract was investigated by means of polyethylene glycol (PEG), given orally. The PEG solutions contained oligomers with molecular weights from 414 to 1206. The urinary recovery of ingested PEG was determined by high performance liquid chromatography (HPLC). Considerable inter- and intra-individual variations in recovery were found in a reference group of 33 healthy subjects. Intake of food did not change the recovery of PEG, 6.11% (SEM 0.52, n = 13) compared with that for the reference group, 6.45% (SEM 0.39, n = 33). The PEG recovery in a group of ileostomy patients was 5.86% (SEM 0.62, n = 13). No correlation was found between PEG recovery and small bowel transit time. The lipophillic properties of PEG were determined by measuring the partition coefficients in 1-octanol/water and in methylhexanoate/water systems. From these results, correlated with the values for the hydrodynamic volumes of PEG, it was concluded that the intestinal permeation of PEG observed was probably determined by the hydrophillic/hydrophobic properties of the mucosal membrane, rather than by the presence of intercellular junctions or paracellular pores. The PEG molecules with molecular weights from 414 to 1206 were, therefore, not suitable as solitary probes for permeability studies in man.

Administration, Oral↗
PubMed1988

Treatment of hydrocele testis by injection of tetracycline.

In a prospective study 27 hydroceles were treated with single aspiration and injection of 500 mg tetracycline. The median observation period was 6 months (range 3-15 months). One month after therapy 9 recurrences were observed; but 5 disappeared spontaneously during the next 2 months, giving an overall success rate of 85% (95% confidence limits 66-96%). No serious complications occurred. Dilution of tetracycline in lidocaine prevented acute scrotal pain. Sclerotherapy with tetracycline is efficient, easy and inexpensive and, therefore, economical and beneficial for the patient.

Adult↗