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J Engberg

Publications and source records attributed to J Engberg.

87 records · Page 5Linked to original sources
PubMed1976

Studies on the amount and location of the tRNA and 5-S rRNA genes in Tetrahymena pyriformis GL.

The amount and location of tRNA and 5-S rRNA genes in the macronucleus of Tetrahymena pyriformis GL was investigated by DNA-RNA hybridization. Hybridization of 32P-labelled tRNA in excess of unlabelled rRNA (25-S + 17-S + 5-S) showed that at saturation 0.021% of the macronuclear DNA was complementary to tRNA. Hybridization of 32P-labelled 5-S rRNA in excess of unlabelled 25-S + 17-S rRNA and tRNA showed a saturation value of 0.017%. In contrast to the 25-S + 17-S rRNA genes, which are found in DNA of high bouyant density, tRNA and 5-S rRNA genes were distributed evenly throughout the main peak observed when bulk macronuclear DNA was fractionated by density centrifugation in CsCl gradients. Sucrose gradient analyses of total macronuclear DNA showed that tRNA and 5-S rRNA genes were found in DNA of all size classes but a significant enrichment in the slowly sedimenting DNA fraction was observed. Saturation hybridization of 5-S rRNA to purified rDNA showed that rDNA did not contain any 5-S rRNA genes.

Animals↗
PubMed1974

Induction of nucleolar and mitochondrial DNA replication in Tetrahymena pyriformis.

Selective induction of replication of nucleolar and mitochondrial DNA has been demonstrated in starved-refed cultures of Tetrahymena pyriformis by different techniques. Labeling of starved cells with [(3)H]thymidine during a nutritional shift-up and analysis of the DNA in isopycnic CsCl gradients shows that the two initially labeled species of DNA are two species banding on the heavy and light side of the bulk macronuclear DNA. In isolated macronuclei the radioactivity is found only in the high density fraction, which has been shown to be of nucleolar origin. In sucrose gradients the newly replicated mitochondrial and nucleolar DNAs sediment considerably slower than the bulk DNA, as one discrete band corresponding to a molecular weight of about 3 to 4 x 10(7). Electron microscope autoradiography of cells labeled with [(3)H]thymidine as above shows that the peripheral nucleoli of the macronucleus as well as the mitochondria are labeled before any radioactivity is found in the chromatin granules of the macronucleus. The results clearly indicate that nucleolar and mitochondrial DNA replication are under a control independent of that for the replication of bulk DNA.

Animals↗
PubMedDate not supplied

Antimicrobial resistance of thermophilic Campylobacter.

Campylobacter has become the leading cause of zoonotic enteric infections in developed and developing countries world-wide. Antimicrobial resistance has emerged among Campylobacter mainly as a consequence of the use of antimicrobial agents in food animal production. Resistance to drugs of choice for the treatment of infections, macrolides and fluoroquinolones has emerged as a clinical problem and interventions to reduce this are recommended. Resistance to fluoroquinolones and macrolides is mediated by chromosomal mutations. Resistance to other relevant antimicrobial agents, mediated by acquired resistance genes, has not become widespread so far. However, resistance genes originating from both Gram-positive and Gram-negative bacterial species have been found, showing the potential for acquired resistance to emerge in Campylobacter.

Animals↗
PubMedDate not supplied

HMO market structure and performance: 1985-1995.

This paper estimates the effect of market structure on hospital days and ambulatory visits in independent practice associations (IPAs) and group-model health maintenance organizations (HMOs) where market structure is measured by HMO penetration and the number of HMOs operating in a market. There was a steady decline in inpatient use in HMOs during the study period and a steady increase in use of ambulatory care. In multivariate analyses, inpatient use is significantly higher in IPAs, but there is no difference in ambulatory use. As HMO penetration increases and the number of HMOs increases, group-model HMOs have lower hospital use and greater ambulatory use. In contrast, use of both inpatient and ambulatory care decreases in IPAs but only at high levels of penetration and numbers of competitors.

Ambulatory Care↗
PubMedDate not supplied

Quinolone and macrolide resistance in Campylobacter jejuni and C. coli: resistance mechanisms and trends in human isolates.

The incidence of human Campylobacter jejuni and C. coli infections has increased markedly in many parts of the world in the last decade as has the number of quinolone-resistant and, to a lesser extent, macrolide-resistant Campylobacter strains causing infections. We review macrolide and quinolone resistance in Campylobacter and track resistance trends in human clinical isolates in relation to use of these agents in food animals. Susceptibility data suggest that erythromycin and other macrolides should remain the drugs of choice in most regions, with systematic surveillance and control measures maintained, but fluoroquinolones may now be of limited use in the empiric treatment of Campylobacter infections in many regions.

Animal Diseases↗