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Biomedical subjects

Robert Carlson

Publications and source records attributed to Robert Carlson.

6 recordsLinked to original sources
PubMed2004

Using protein-DNA chimeras to detect and count small numbers of molecules.

We describe general methods to detect and quantify small numbers of specific molecules. We redirected self-splicing protein inteins to create 'tadpoles', chimeric molecules comprised of a protein head covalently coupled to an oligonucleotide tail. We made different classes of tadpoles that bind specific targets, including Bacillus anthracis protective antigen and the enzyme cofactor biotin. We measured the amount of bound target by quantifying DNA tails by T7 RNA polymerase runoff transcription and real-time polymerase chain reaction (PCR) evaluated by rigorous statistical methods. These assays had a dynamic range of detection of more than 11 orders of magnitude and distinguished numbers of molecules that differed by as little as 10%. At their low limit, these assays were used to detect as few as 6,400 protective antigen molecules, 600 biotin molecules and 150 biotinylated protein molecules. In crudely fractionated human serum, the assays were used to detect as few as 32,000 protective antigen molecules. Tadpoles thus enable sensitive detection and precise quantification of molecules other than DNA and RNA.

Antigens, Bacterial↗
PubMed2004

The synergistic effects of betulin with acyclovir against herpes simplex viruses.

Betulin, a pentacyclic triterpenoid, was isolated from the bark of Betula papyrifera. The antiviral efficacies of betulin on herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) were evaluated using viral plaque reduction assays on Vero cells. The results indicate that betulin is active against both HSV-1 and HSV-2 infections with the 50% effective concentrations (EC(50)) of 0.40 and 4.15 microg/ml, respectively. The cytotoxicity of betulin was examined on Vero cells using a neutral red uptake assay. The 50% cytotoxic concentration (CC(50)) of betulin was 73.1 microg/ml. A synergistic antiviral effect between betulin and acyclovir (ACV) was determined by drug combination studies. Strong and moderate synergistic antiviral effects were observed for betulin and ACV against HSV-1 when the concentrations of ACV and betulin were higher than 0.068 and 0.4 microg/ml, respectively. At the concentrations lower than these, additive effect was found. Synergistic antiviral effects were also found against HSV-2 at higher concentrations than for HSV-1, i.e. 0.45 microg/ml of ACV combined with 8.4 microg/ml of betulin.

Acyclovir↗