Strategies for detection of transfusion-transmitted viruses eluding identification by conventional serologic tests. II. Detection of host DNA in human plasmas with elevated alanine aminotransferase

Branched DNA-based Alu quantitative assay for cell-free plasma DNA levels in patients with sepsis or systemic inflammatory response syndrome

Cell-free circulating DNA (cf-DNA) can be detected by various of laboratory techniques. We described a branched DNA-based Alu assay for measuring cf-DNA in septic patients. Compared to healthy controls and systemic inflammatory response syndrome (SIRS) patients, serum cf-DNA levels were significantly higher in septic patients (1426.54 ± 863.79 vs 692.02 ± 703.06 and 69.66 ± 24.66 ng/mL). The areas under the receiver operating characteristic curve of cf-DNA for normal vs sepsis and SIRS vs sepsis were 0.955 (0.884-1.025), and 0.856 (0.749-0.929), respectively. There was a positive correlation between cf-DNA and interleukin 6 or procalcitonin or Acute Physiology and Chronic Health Evaluation II. The cf-DNA concentration was higher in intensive care unit nonsurviving patients compared to surviving patients (2183.33 ± 615.26 vs 972.46 ± 648.36 ng/mL; P < .05). Branched DNA-based Alu assays are feasible and useful to quantify serum cf-DNA levels. Increased cf-DNA levels in septic patients might complement C-reactive protein and procalcitonin in a multiple marker format. Cell-free circulating DNA might be a new marker in discrimination of sepsis and SIRS.

Extracellular DNA Level in the Blood of Irradiated Rats

There is high-molecular DNA in the blood of unirradiated rats which moves as a single fraction during electrophoresis in 0.5% agarose. At short times (2-5 h) after gamma-irradiation at doses from 1 to 100 Gy a low-molecular species of DNA appears (about 180 nucleotide pairs), the amount of which is directly proportional to exposure dose at 5 h after exposure. It has been established by Southern hybridization that the low-molecular DNA has few nucleotide sequences common with those of the high-molecular DNA, but it shows homologously to genomic sequences.

Detection of mutated K-ras DNA in urine, plasma, and serum of patients with colorectal carcinoma or adenomatous polyps

Our previous studies demonstrated that urine contains DNA derived from the circulation and that this DNA originated, in part, from organ sites and tumors distal to the urinary tract. To explore the potential use of DNA from urine as compared to other body fluids as a source for circulating DNA for cancer detection, the DNA concentration and the frequency of detection of mutated Kristin-ras (K-ras) DNA in serum, plasma, and urine were examined. The concentration of DNA in the urine was similar to that in the serum, but the DNA concentration in plasma was significantly lower than in either urine or serum (P < 0.05). When DNA derived from 10 muL of body fluid was used in each mutation assay, the detection frequency of mutated K-ras DNA was comparable among serum, plasma, and urine. However, when DNA derived from 200 muL of body fluid was used, the incidence of detecting mutated K-ras DNA in urine was significant higher (95%) than in either serum (35%) or plasma (40%) (P < 0.0005), suggesting that inhibitory factors in serum/plasma may be more limiting than in urine. The use and practicality of urine as a source of circulating DNA for cancer detection are discussed.

Isolation and characterization of DNA from the plasma of cancer patients

Ten out of 37 patients with advanced malignant diseases were found to have extractable amounts of DNA in their plasma whereas no DNA could be detected in 50 normal controls. After its purification from the original nucleoprotein complex, DNA plasma levels ranging from 0.15 to 12 micrograms/ml were measured, the lowest concentration detectable with our method being 0.1 microgram/ml. Knowing from recovery experiments performed with 32P-DNA that the loss of DNA during the extraction procedure is about 65%, the real concentration of DNA in the plasma corresponds to about 3 times the given figures. The purified DNA was shown to be double-stranded and composed of fractions ranging from 21 kb to less than 0.5 kb, as determined by agarose gel electrophoresis. All these fractions hybridized with a 32P-labelled human DNA probe indicating the human origin of the bulk of the circulating DNA.

IN CONCLUSION

the finding of extractable amounts of DNA in the plasma of 27% of the investigated cancer patients, and its absence from the controls, suggests some correlation with malignancy.

Search for hepatitis B virus DNA in sera from patients with acute type B or non-A, non-B hepatitis

One hundred and three single sera from adults hospitalized with acute type B (78) or non-A, non-B (25) hepatitis were tested for the presence of hepatitis B virus DNA (HBV DNA). All sera from patients with type B hepatitis were IgM anti-HBc-positive. These patients were classified as benign (47) or fulminant (31) hepatitis. The 25 acute non-A, non-B patients were also classified as benign (21) or fulminant (4) hepatitis and were negative for serologic markers of past HBV infection. Serum HBV DNA was detected with similar frequency in benign (38.5%) and fulminant (FH, 34.6%) HBsAg-positive cases. HBV DNA was not detected in either the 26 acute HBsAg-negative hepatitis B cases who were positive for anti-HBc and anti-HBs or the 25 acute non-A, non-B hepatitis cases. The absence of HBV DNA in 43.8% of benign hepatitis B patients who were positive for HBsAg and HBeAg could possibly be attributed to either low level replication of HBV that was not detectable by the [32P]HBV DNA probe or to a period of delayed clearance of free HBeAg following cessation of HBV replication. Emergence of anti-HBs in the presence of HBsAg did not always correspond to clearance of HBV in fulminant type B cases. However, in acute type B hepatitis, irrespectively of severity, disappearance of HBsAg and appearance of anti-HBs was accompanied by reduction of HBV replication to undetectable levels.

Comparative study of DHBV DNA levels and endogenous DNA polymerase activity in naturally infected ducklings in France

Duck hepatitis B virus (DHBV) was found in the serum of 1-6% of Pekin ducklings originated from French commercial flocks. The viremia was followed in the serum of 5 ducklings over a span of 3 mth by monitoring the levels of DHBV DNA and the endogenous DNA polymerase (DNAp) activity. The DHBV DNA levels in serum were quantified either by the DNA dot hybridization technique including counting of retained radioactivity, or by successive dilutions of each serum sample followed by DNA hybridization. The counting of the retained radioactivity was plotted on a curve and its evolution compared with that of viral DNAp activity. DHBV DNA levels in serum, estimated by both methods paralleled those of the DNAp activity, which peaked at the 4th or 5th week posthatch to decrease and fluctuate thereafter. Occasional discordance between DHBV DNA levels and the endogenous DNAp activity was observed, which could be correlated with the degree of repair of the single stranded gap of serum DHBV DNA. Parallel follow up studies comparing quantitative estimations of serum viral DNA and of DNAp activity, as presented here, may provide some clues for the understanding of the mechanisms involved in the establishment of the HEPA DNA virus carrier state. Such comparative studies may also be crucial for optimal monitoring of antiviral drugs in both human clinical trials and animal experimental studies.