Biomedical subjects

D K Chung

Publications and source records attributed to D K Chung.

At least 19 recordsLinked to original sources

PubMed1992

Antisense RNA directed against the major capsid protein of Lactococcus lactis subsp. cremoris bacteriophage 4-1 confers partial resistance to the host.

Antisense RNA targeted against the major capsid protein (MCP) of Lactococcus lactis subsp. cremoris bacteriophage F4-1 reduced bacteriophage replication by up to 50%. The region containing the mcp gene was oriented to transcribe the antisense strand using a L. lactis subsp. cremoris Wg2 promoter. The size of the mcp insert transcribed affected the level of bacteriophage inhibition and the greatest level of inhibition was achieved using a 301-bp fragment from the 5' end of the mcp. Antisense mcp RNA constructs were stable and did not alter the endogenous plasmid profile in the host, L. lactis subsp. cremoris F4-1. There were, however, some adverse effects on the host during the stationary phase as exhibited by a decline in cell density.

Bacteriophages↗

PubMed1992

Use of antisense RNA to confer bacteriophage resistance in dairy starter cultures.

The strategy and implementation of a unique system for engineering bacteriophage resistant starter cultures of Lactococcus lactis employing antisense RNA is reviewed. As a necessary prerequisite for developing this system, we have cloned and sequenced a number of bacteriophage genes coding for minor and major structural proteins. In addition, we have also identified a series of genes whose function(s) is not known but their sequences appear to be conserved in a vast number of isolates. One of these latter sequences, designated gp51C, codes for a 51-kDa protein which is extremely charged and shares some homology with yeast translation initiation factor. Resistance to a broad class of isometric bacteriophages has been achieved by expression of an antisense RNA targeted against, for example, gp51C. In the best case, expression of the antisense gp51C RNA results is a greater than 99% reduction in the total number of plaque forming units. Additional antisense RNA constructs directed against other bacteriophage genes, including the major capsid protein, also appear effective at inhibiting infection from 40-55% suggesting that this approach may prove useful for engineering a set of truly isogenic strains to be used in a starter culture rotation plan.

Bacteriophages↗

PubMed1991

Cloning and nucleotide sequence of the major capsid protein from Lactococcus lactis ssp. cremoris bacteriophage F4-1.

The gene (mcp) coding for the major capsid protein (MCP) of the Lactococcus lactis ssp. cremoris bacteriophage F4-1 has been cloned and its nucleotide sequence determined. The mcp gene was localized, by Western blotting with rabbit antiserum against intact bacteriophage, within a 3.3-kb HindIII-Spe I fragment and the sequence of the entire region determined. The 35-kDa MCP is coded for by a 905-bp open reading frame preceded by a putative ribosome-binding site. Deletion analysis and N-terminal sequencing of the MCP confirmed the identification of the gene coding for this bacteriophage MCP.

Amino Acid Sequence↗

PubMed1989

Percutaneous fine needle aspiration biopsy of pancreatic cancer guided by ultrasonography.

Fine needle aspiration biopsy guided by ultrasonography was performed in 39 patients with pancreatic cancer to evaluate the value of the technique for establishing a proved histologic diagnosis. Aspirated material suitable for cytologic evaluation of smear preparation was obtained from 33 patients (84.6%). Among the 33 patients, cytologic diagnosis of pancreatic cancer was possible in 28 patients (84.9%). There was mild abdominal pain only in one patient (2.6%). In conclusion, percutaneous fine needle aspiration biopsy guided by ultrasonography proved to be a safe and useful method for histologic diagnosis of pancreatic cancer.

Adult↗

PubMed1973