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Biomedical subjects

E Kristiansen

Publications and source records attributed to E Kristiansen.

At least 19 recordsLinked to original sources
PubMed1992

Effect of a dietary fiber (beet fiber) on dimethylhydrazine-induced colon cancer in Wistar rats.

The modifying effect of a dietary fiber, Fibeta (beet fiber), on experimentally induced colorectal cancer was studied in Wistar rats. The rats were fed a powdered semisynthetic casein-based diet in which the carbohydrate pool was substituted with Fibeta as the sole source of fiber. Dimethylhydrazine dihydrochloride (DMH-2HCl) was used as initiator in a dose of 20 mg/kg body wt and given by gavage once a week for 10 weeks. Throughout the experiment the rats were offered the diets with different levels of fiber in a preinitiation period of 8 weeks, during the initiation, or in a 30-week postinitiation period. The study was terminated after one year. A protective effect of the fiber was not found at any stage of the colorectal carcinogenic process. Even though differences (not statistically significant) in tumor incidences were seen, these did not reflect any effect of the high or low fiber intake during the study. Analysis for volatile fatty acids in cecal content showed that continuous feeding with a fiber-rich diet resulted in significant increase in most of the volatile fatty acids. The relative change was highest for butyric acid. These findings do not support the hypothesis that butyric acid has a protective effect on colorectal cancer. The tumor yield in the present study was low compared with that reported in the literature, and possible causes for this are discussed.

Animals↗
PubMed1992

Escherichia coli K-12 and B contain functional bacteriophage P2 ogr genes.

The bacteriophage P2 ogr gene encodes an essential 72-amino-acid protein which acts as a positive regulator of P2 late transcription. A P2 ogr deletion phage, which depends on the supply of Ogr protein in trans for lytic growth on Escherichia coli C, has previously been constructed. E. coli B and K-12 were found to support the growth of the ogr-defective P2 phage because of the presence of functional ogr genes located in cryptic P2-like prophages in these strains. The cryptic ogr genes were cloned and sequenced. Compared with the P2 wild-type ogr gene, the ogr genes in the B and K-12 strains are conserved, containing mostly silent base substitutions. One of the base substitutions in the K-12 ogr gene results in replacement of an alanine with valine at position 57 in the Ogr protein but does not seem to affect the function of Ogr as a transcriptional activator. The cryptic ogr genes are constitutively transcribed, apparently at a higher level than the wild-type ogr gene in a P2 lysogen.

Amino Acid Sequence↗
PubMed1991

Detection of genital papillomavirus types by polymerase chain reaction using common primers.

We describe the detection of eight genital human papillomavirus (HPV) types, including HPV16 and HPV18, by PCR amplification of a 323 base-pair region of the genome within the L1 open reading frame (ORF). The primer sequences are: TGYAAATATCCWGATTWTWT and GTATCWACMACAGTAACAAA. The method will detect purified HPV16 DNA down to a concentration of as little as a single molecule in 100 microliters. The method is also applicable to purified DNA and crude lysates from tumour biopsies. Typing of the PCR product can be achieved with specific oligonucleotide probes.

Base Sequence↗
PubMed1990

Chronic ethanol intake and reduction of lung tumours from urethane in strain A mice.

Combinations of ethanol and urethane were added to the drinking-water of female strain A/Ph mice for 12 wk, at the end of which the animals were killed. Urethane concentrations were 0, 200, 500 and 1000 ppm and ethanol concentrations, 0, 5, 10 and 20% (v/v). All possible combinations of these urethane and ethanol concentrations were tested. Urethane induced primary lung adenomas in all treated mice in a dose-dependent manner. An average of 71 +/- 15 tumours/mouse were found, when the animals were killed, after treatment with 1000 ppm urethane for 12 wk. Ethanol alone did not alter the background incidence of tumours and produced only marginal hepatotoxicity. The tumour yields induced by urethane treatment were greatly reduced by simultaneous treatment with ethanol. The effect of ethanol was independent of urethane dose. When the concentrations of ethanol in the drinking-water were 20 and 10% the incidences of lung adenomas induced by urethane were reduced by about two-thirds and one-half, respectively. The effect of 5% ethanol, if any, was not statistically significant.

Adenoma↗
PubMed1990

Herniation of the liver through the diaphragm in Mol: WIST rats.

The occurrence of herniation of liver through the diaphragm in Mol: WIST rats from toxicological studies conducted over a period of approximately 15 years at the Institute of Toxicology, National Food Agency, Denmark, is described. The incidence of diaphragmatic hernia in male rats indicates a tendency toward an increase through the years. The long term carcinogenicity studies initiated in 1971, 1976 and 1982 (age of the rats at necropsy approximately 2 1/2 year) revealed no diaphragmatic hernias in the 1971 study and 4% in both the 1976 and the 1982 study. In females, 0%, 1% and 1% respectively with diaphragmatic hernias were found. Among the animals from two one-year studies, only with male rats, initiated in 1985 and 1987 respectively, 7% and 5% of the males had diaphragmatic hernias.

Animals↗
PubMed1989

Chromosomal analyses of human lymphocytes exposed in vitro to caprolactam.

Caprolactam was tested for the induction of chromosomal aberrations in cultured human lymphocytes from one male donor and one female donor. At 7.5 mg/ml, caprolactam-treated cells from the male showed a small but significant increase in the frequency of aberrations. No effect was observed in cells from the female if gaps are excluded.

Adult↗
PubMed1989

Carcinogenic potential of cooked food mutagens (IQ and MeIQ) in Wistar rats after short-term exposure.

Two potent cooked food mutagens, 2-amino-3-methylimidazo/4,5-f/quinoline (IQ) and 2-amino-3,4-dimethylimidazo/4,5-f/quinoline (MeIQ), were examined in an initiation-promotion assay in the male wistar rat. Fourteen doses of 10 mg IQ or 10 mg MeIQ/kg b.wt. were given during initiation, followed by promotion with 500 p.p.m. phenobarbital sodium (PB) in the drinking water up to week 58. A small number of tumours of Zymbal's gland were seen in all groups treated with IQ or MeIQ, irrespective of PB-treatment. Though the promotional regimen failed to produce the expected number of liver tumours, it did induce a significant amount of gamma-glutamyltranspeptidase (GGT) activity. These results suggest that even short exposures to low doses of IQ or MeIQ produce persistent procarcinogenic lesions in the rat, and that secondary factors, e.g. promoters or high cell turnover, may over time develop these lesions into cancer.

Animals↗
PubMed1989

Effects of dietary protein and butylated hydroxytoluene on the kidneys of rats.

Semipurified diet using Na-caseinate or lactalbumin as the only protein source was given to female rats to study the influence of nephrocalcinosis on butylated hydroxytoluene (BHT) induced kidney damage. The study showed, that BHT induces nephropathy in female rats irrespective of the diet used. Pronounced nephrocalcinosis was only found in rats fed the Na-caseinate diet. Thus, this study does not indicate a connection between the development of the BHT-nephropathy and nephrocalcinosis. The results from this study once more stress the influence of the diet on reaction of the animal to experimental procedures.

Animals↗