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C Jørgensen

Publications and source records attributed to C Jørgensen.

9 recordsLinked to original sources
PubMed1999

Isolation and characterization of mutations in the Escherichia coli regulatory protein XapR.

In this work, the LysR-type protein XapR has been subjected to a mutational analysis. XapR regulates the expression of xanthosine phosphorylase (XapA), a purine nucleoside phosphorylase in Escherichia coli. In the wild type, full expression of XapA requires both a functional XapR protein and the inducer xanthosine. Here we show that deoxyinosine can also function as an inducer in the wild type, although not to the same extent as xanthosine. We have isolated and characterized in detail the mutants that can be induced by other nucleosides as well as xanthosine. Sequencing of the mutants has revealed that two regions in XapR are important for correct interactions between the inducer and XapR. One region is defined by amino acids 104 and 132, and the other region, containing most of the isolated mutations, is found between amino acids 203 and 210. These regions, when modelled into the three-dimensional structure of CysB from Klebsiella aerogenes, are placed close together and are most probably directly involved in binding the inducer xanthosine.

Base Sequence↗
PubMed1999

MULTISCAN--a Scandinavian multicenter second trimester obstetric ultrasound and serum screening study.

AIM: To study the detection rates of second trimester ultrasound screening for neural tube defects (NTD), abdominal wall defects (AWD) and Down's syndrome (DS) in low risk populations at tertiary centers, and to compare the ultrasound screening detection rates with those that were obtainable by biochemical serum screening (double test: alpha-fetoprotein/human chorion gonadotrophin/age test). STUDY DESIGN: Prospective multicenter study with a three year inclusion period: 1/1/1989-31/12/1991. SUBJECTS: 27,844 low-risk women at 18-34 years of age who had a second trimester ultrasound screening examination. Of these, 10,264 also had a serum test. METHODS: An ultrasound malformation scan and a serum test were carried out at 17-19 weeks of gestation. Risk calculations regarding DS were based on alpha-fetoprotein, human chorion gonadotrophin and maternal age; performed retrospectively for the first two years. RESULTS: In total 73 cases were identified in the study population: NTD (n=34), AWD (n=7) and DS (n=32). The detection rates, (%, with 95% confidence interval) for ultrasound screening were: NTD: 79.4 (62.1-91.3); AWD: 85.7 (42.1-99.6); DS: 6.3 (0.8-20.8). In the subgroup of women who had both tests, the detection rates for ultrasound screening vs double test were: NTD: 62.5 (24.5-91.5) vs 75.0 (34.9-96.8); AWD: 66.7 (9.4-99.2) vs 100 (29.2-100.0); DS: 7.7 (0.2-36.0) vs 46.2 (19.2-74.9). The false positive rates (%) for ultrasound screening vs double test were: NTD: 0.01/3.3; AWD: 0.01/3.3; DS: 0.1/4.0. CONCLUSION: Second trimester ultrasound screening in a low risk population gave a low detection rate for fetal DS (6.3%) and an acceptable detection rate for NTD (79.4%) and AWD (85.7%). In the subgroup of women who had both tests, serum screening performed better than ultrasound as applied in the present study, especially regarding DS.

Abdominal Muscles↗
PubMed1995

Transformation of o-xylene to o-methyl benzoic acid by a denitrifying enrichment culture using toluene as the primary substrate.

A highly enriched denitrifying mixed culture transformed o-xylene co-metabolically along with toluene by methyl group oxidation. o-Methyl benzaldehyde and o-methyl benzoic acid accumulated transiently as metabolic products of o-xylene transformation. Transformation of o-methyl benzyl alcohol and o-methyl benzaldehyde occurred independently of toluene degradation and resulted in the formation of a compound coeluting with o-methyl benzoic acid on a gas chromatograph. The co-metabolic relationship between toluene and o-xylene could be attributed to a mechanism linked to the initial oxidation of the methyl group.

Bacteria, Anaerobic↗
PubMed1995

Stoichiometry and kinetics of microbial toluene degradation under denitrifying conditions.

Batch experiments were carried out to investigate the stoichiometry and kinetics of microbial degradation of toluene under denitrifying conditions. The inoculum originated from a mixture of sludges from sewage treatment plants with alternating nitrification and denitrification. The culture was able to degrade toluene under anaerobic conditions in the presence of nitrate, nitrite, nitric oxide, or nitrous oxide. No degradation occurred in the absence of Noxides. The culture was also able to use oxygen, but ferric iron could not be used as an electron acceptor. In experiments with 14C-labeled toluene, 34% +/- 8% of the carbon was incorporated into the biomass, while 53% +/- 10% was recovered as 14CO2, and 6% +/- 2% remained in the medium as nonvolatile water soluble products. The average consumption of nitrate in experiments, where all the reduced nitrate was recovered as nitrite, was 1.3 +/- 0.2 mg of nitrate-N per mg of toluene. This nitrate reduction accounted for 70% of the electrons donated during the oxidation of toluene. When nitrate was reduced to nitrogen gas, the consumption was 0.7 +/- 0.2 mg per mg of toluene, accounting for 97% of the donated electrons. Since the ammonia concentration decreased during degradation, dissimilatory reduction of nitrate to ammonia was not the reductive process. The degradation of toluene was modelled by classical Monod kinetics. The maximum specific rate of degradation, k, was estimated to be 0.71 mg toluene per mg of protein per hour, and the Monod saturation constant, Ks, to be 0.2 mg toluene/l. The maximum specific growth rate, mu max, was estimated to be 0.1 per hour, and the yield coefficient, Y, was 0.14 mg protein per mg toluene.

Bacteria, Anaerobic↗
PubMed1993

Biodegradation of ortho-cresol by a mixed culture of nitrate-reducing bacteria growing on toluene.

A mixed culture of nitrate-reducing bacteria degraded o-cresol in the presence of toulene as a primary growth substrate. No degradation of o-cresol was observed in the absence of toluene or when the culture grew on p-cresol and 2,4-dimethylphenol. In batch cultures, the degradation of o-cresol started after toluene was degraded to below 0.5 to 1.0 mg/liter but continued only for about 3 to 5 days after the depletion of toluene since the culture had a limited capacity for o-cresol degradation once toluene was depleted. The total amount of o-cresol degraded was proportional to the amount of toluene metabolized, with an average yield of 0.47 mg of o-cresol degraded per mg of toluene metabolized. Experiments with [ring-U-14C]o-cresol indicated that about 73% of the carbon from degraded o-cresol was mineralized to CO2 and about 23% was assimilated into biomass after the transient accumulation of unidentified water-soluble intermediates. A mathematical model based on a simplified Monod equation is used to describe the kinetics of o-cresol degradation. In this model, the biomass activity toward o-cresol is assumed to decay according to first-order kinetics once toluene is depleted. On the basis of nonlinear regression of the data, the maximum specific rate of o-cresol degradation was estimated to be 0.4 mg of o-cresol per mg of biomass protein per h, and the first-order decay constant for o-cresol-degrading biomass activity was estimated to be 0.15 h-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Biodegradation, Environmental↗
PubMed1990

Ultrasound examination for detection of ovarian carcinoma in risk groups.

Ovarian ultrasound scanning was carried out as an adjunct to pelvic examination in 801 women between 40-70 years of age presenting at the outpatient Department of Obstetrics and Gynecology, University Hospital, Lund, Sweden for a variety of gynecologic complaints. All belonged to a high-risk category for ovarian carcinoma because of nulliparity; family history of ovarian, breast, or endometrial carcinoma; previous cancer; or unspecified abdominal complaints. Of 638 patients with normal scans, findings at pelvic examination had been abnormal in 51 cases, and all were normal at subsequent clinical follow-up. Among 163 patients with abnormal ultrasound scans, one case of borderline ovarian tumor and two cases of endometrial cancer were found for which the pelvic examination had been considered normal. Clinical symptoms probably would have led to detection within a short time in these cases anyway, even if ultrasound had not been performed. Based on the findings in this study and the previous experience with gynecologic ultrasound in several thousand patients, it would not seem that ultrasound has a role in screening for ovarian carcinoma.

Adult↗
PubMed1989

[Occurrence of the yeast, Cryptococcus (Cr) neoformans, in pigeon droppings].

Pigeon droppings were collected in Copenhagen and Odense. In samples from pigeon lofts, cryptococci were found in 33% from Copenhagen and in 16% from Odense. All of the species of cryptococci found were Cr. neoformans. These findings are compared with the previous Danish investigations. The frequent occurrence of cryptococci in AIDS patients is mentioned.

Animals↗