PubMed Health⌕ Search

Biomedical subjects

M Hakkinen

Publications and source records attributed to M Hakkinen.

7 recordsLinked to original sources
PubMed1999

Stability of related human and chicken Campylobacter jejuni genotypes after passage through chick intestine studied by pulsed-field gel electrophoresis.

The genomic stability of 12 Campylobacter jejuni strains consisting of two groups of human and chicken isolates was studied by analysis of their PFGE (pulsed-field gel electrophoresis) patterns after passage through newly hatched chicks' intestines. The patterns of SmaI, SalI, and SacII digests remained stable after intestinal passage, except for those of two strains. One originally human strain, FB 6371, changed its genotype from II/A (SmaI/SacII) to I/B. Another strain, BTI, originally isolated from a chicken, changed its genotype from I/B to a new genotype. The genomic instability of the strains was further confirmed by SalI digestion and ribotyping of the HaeIII digests. In addition, heat-stable serotype 57 of strain FB 6371 changed to serotype 27 in all isolates with new genotypes but remained unchanged in an isolate with the original genotype. Serotype 27 of strain BTI remained stable. Our study suggests that during intestinal colonization, genomic rearrangement, as demonstrated by changed PFGE and ribopatterns, may occur.

Animals↗
PubMed1998

Effects of growth-promoting antimicrobials on inhibition of Yersinia enterocolitica O:3 by porcine ileal microflora.

The survival of Yersinia enterocolitica serotype O:3 was examined in an in vitro model of the porcine ileum in the presence of normal ileal microflora using a medium supplemented with the growth-promoting antimicrobials avoparcin, spiramycin, tylosin, carbadox and olaquindox, or without any antimicrobials, at 39 degrees C for 5 d. Growth of Y. enterocolitica was inhibited in all trials in the following order: avoparcin < carbadox < spiramycin < no feed additives < tylosin < olaquindox. The media supplemented with avoparcin, carbadox and spiramycin supported the survival of Y. enterocolitica up to 5 d. When incubated with the normal ileal microflora without any growth-promoting antimicrobials, Y. enterocolitica could not be isolated after 4 d. With olaquindox and tylosin, Y. enterocolitica was not detected after 3 d.

Animals↗
PubMed1998

Comparison of two different types of competitive exclusion products.

The efficacy of two different types of commercial competitive exclusion (CE) products against Salmonella was studied in three chicken assay trials. Chicks were treated on the day of hatch and challenged one day later either with Salm. infantis (Trials 1 and 2) or a combination of Salm. infantis and Salm. enteritidis (Trial 3). The caeca of the birds were examined for Salmonella five days after challenge. The mean logarithmic counts of Salmonella were from 3.4 to 5.7 in the groups treated with product. A derived from the whole caecal contents of an adult bird, from 0.0 to 1.2 in the groups treated with product B, a highly selected product that does not contain any clostridia, and from 6.3 to 7.6 in the control groups. None of the challenge organisms superseded the other in Trial 3, and neither did the double challenge affect the protective capacity of the treatment materials.

Animals↗
PubMed1997

Frictional work in double-sided tablet compression.

The aim of this study was to evaluate the friction during double-sided tablet compression. Dicalcium phosphate dihydrate and lactose were tabletted with a compaction simulator with symmetrical and asymmetrical double-sided sawtooth punch displacement profiles. The estimation of force transmission in a powder column was based on an exponential equation, including the material parameter consisting of both the friction coefficient and Poisson's ratio. This parameter was predetermined from a single-sided compression. A novel equation was derived from a previously presented equation for friction work in single-sided tablet compression. The basic assumption was drawn from the linearly decreasing movement of infinitely thin particle layers, which are produced as the compressing punch surface approaches the other punch. This calculation was also based on the assumption that the equilibrium point, where the particles do not move, is halfway between the punches in the symmetrical profile and at a distance proportional to the amplitudes of the asymmetrical upper and lower sawtooth profiles. The tensile strength of tablets compressed with single-double-sided profiles was identical, and thus the behavior of the materials studied under compression was independent of the compression profiles. The friction work values that were calculated with the proposed expression for double-sided profiles were close to the theoretical values, as estimated by calculations based on compressions with single-sided profiles. In conclusion, the novel mathematical expression opens new possibilities for the evaluation of friction in double-sided compression; for example, in rotary press tabletting.

Friction↗
PubMed1996

Efficacy of a commercial competitive exclusion product against a chicken pathogenic Escherichia coli and E coli O157:H7.

The prevention of caecal colonisation of chicks by a poultry pathogenic Escherichia coli O20:K-:H8 and the human pathogenic E coli O157:H7 was studied in vivo in four one-week laboratory trials. Chicks were treated with a competitive exclusion product on the day of hatch and challenged one day later. The poultry pathogenic serotype showed higher levels of caecal colonisation than the human pathogenic serotype, but the protection against both pathogens was highly significant.

Animals↗
PubMed1996

Note: inhibition of the growth of Yersinia enterocolitica O:3 by the microflora of porcine caecum and ileum in an in vitro model.

The growth of Yersinia enterocolitica O:3 was tested in an in vitro model of the porcine intestine at the physiological temperature of 39 degrees C of growing pigs. The model supported a stable population of Y. enterocolitica at a level 10(8)-10(9) cells ml-1. Plasmid profile analysis and the Ca(2+)-dependent proportion of the population suggested that the great majority of the Y. enterocolitica population retained the 70 kb virulence plasmid, pYV, throughout the experimental period of 5 d. The growth of Y. enterocolitica was substantially inhibited by the ileal and the caecal flora compared to the growth of the bacterium alone. Yersinia enterocolitica was not isolated after 3 d of cultivation.

Animals↗