Recent evidence suggests that cell-free plasma DNA has potential use as a prognostic marker in many clinical settings. The aim of the present study was to evaluate the prognostic role of cell-free plasma DNA in the prediction of clinical outcome in intensive treatment unit (ITU) patients. Cell-free plasma DNA was measured by real-time polymerase chain reaction assay for the beta-globin gene and SOFA score, APACHE II score, CRP concentrations, and clinical outcome (duration of stay, ventilation time, and mortality) were noted in 94 patients on admission to the ITU. The median plasma DNA concentration in ITU patients was 5493 GE/mL and this was significantly (P <0.001) higher than the DNA concentration in healthy subjects (1970 GE/mL). DNA concentration demonstrated a significant correlation with serum C-reactive protein (CRP) (r = 0.363) concentration and Sepsis-related Organ Failure Assessment (SOFA) (r = 0.360) score (P <0.001 for both by Pearson correlation) but not with Acute Physiology And Chronic Health Evaluation (APACHE II) score. Patients on ventilation had significantly higher DNA concentrations compared to nonventilated patients (7362 GE/mL versus 4479 GE/mL; P = 0.004). The median DNA concentration in nonsurvivors was 9148 GE/mL, and this was 2.3-fold greater than that in survivors (3921 GE/ml, P <0.001). ROC analysis of the data indicated a sensitivity of 85% and a specificity of 80% when DNA concentration of 6109 GE/mL was taken as a predictor of death. The data suggest that cell-free plasma DNA concentration is potentially useful as a prognostic marker in ITU patients.

In the present study, we examined whether exposing rats to a high-dose regimen of manganese chloride (Mn) during the postnatal period would depress presynaptic dopamine functioning and alter nonassociative and associative behaviors. To this end, rats were given oral supplements of Mn (750 μg/day) on postnatal days (PD) 1-21. On PD 90, dopamine transporter (DAT) immunoreactivity and [ 3 H]dopamine uptake were assayed in the striatum and nucleus accumbens, while in vivo microdialysis was used to measure dopamine efflux in the same brain regions. The effects of postnatal Mn exposure on nigrostriatal functioning were evaluated by assessing rotorod performance and amphetamine-induced stereotypy in adulthood. In terms of associative processes, both cocaineinduced conditioned place preference (CPP) and sucrose-reinforced operant responding were examined. Results showed that postnatal Mn exposure caused persistent declines in DAT protein expression and [ 3 H]dopamine uptake in the striatum and nucleus accumbens, as well as long-term reductions in striatal dopamine efflux. Rotorod performance did not differ according to exposure condition, however Mn-exposed rats did exhibit substantially more amphetamine-induced stereotypy than vehicle controls. Mn exposure did not alter performance on any aspect of the CPP task (preference, extinction, or reinstatement testing), nor did Mn affect progressive ratio responding (a measure of motivation). Interestingly, acquisition of a fixed ratio task was impaired in Mn-exposed rats, suggesting a deficit in procedural learning. In sum, these results indicate that postnatal Mn exposure causes persistent declines in various indices of presynaptic dopaminergic functioning. Mninduced alterations in striatal functioning may have long-term impact on associative and nonassociative behavior.

Recent evidence has shown elevated levels of cell-free plasma DNA in cancer patients. The aim of the present study was to quantify and compare the levels of cell-free plasma DNA in patients with prostate cancer, prostatic intraepithelial neoplasia (PIN), and benign prostatic hypertrophy (BPH) to examine if it offered a useful diagnostic test. Blood samples were obtained from 37 patients attending a clinic for prostate biopsies. Samples were taken prior to biopsy, within 1 hour of the biopsy, and then 2 weeks later. DNA was extracted using a QIAamp blood kit (Qiagen) and plasma DNA measured, in genome equivalents/milliliter plasma (GE/mL), using real-time quantitative PCR for the beta-globin gene. Prior to biopsy, plasma DNA concentration in BPH patients was 936 GE/mL (median; range: 633-2074 GE/mL), while cancer and PIN patients had significantly higher levels of DNA at 1734 GE/mL (median; range: 351-3131 GE/mL; P = 0.01) and 1780 GE/mL (median; range: 1514-2732 GE/mL; P = 0.04), respectively. Comparison of plasma DNA concentration before and after biopsy showed that 60 minutes after biopsy values were significantly higher in both BPH (1494 GE/mL; range: 613-2522 GE/mL; P = 0.029) and cancer (2758; range: 1498-5226 GE/mL; P = 0.007) patients. ROC analysis of the data indicated a sensitivity of 85% and a specificity of 73% when DNA concentration of 1000 GE/mL was taken as an indicator of malignancy or PIN. The data suggest that quantification of cell-free plasma DNA may have an important diagnostic role in distinguishing benign and malignant prostate disease.

The existence of circulating nucleic acids in plasma and serum (CNAPS) was first described almost six decades ago. However, the prognostic and diagnostic utility of this circulating DNA/RNA has only really begun to be appreciated in the last decade. Earlier studies concentrated mainly on investigations concerned with fetal medicine and oncology, and significant progress was made in both specialities. More recently the field of enquiry has extended further, and attention has turned to other pathologic states, including trauma, sepsis, myocardial infarction, stroke, transplantation, diabetes mellitus, and hematologic disorders. In some of these studies, mitochondrial as well as genomic DNA and tissue-specific mRNA have been analyzed, either quantitatively or qualitatively or both, and have been shown to be modified in the presence of disease. While there is tremendous potential for CNAPS as a clinical modality, many of the emerging studies seem to be confined to a few dedicated labs. Therefore, additional independent studies are necessary in some cases in order to show reproducibility, which will further consolidate the field. Despite this shortcoming, and with the evidently increasing number of applications for CNAPS, it is highly likely that routine testing, as described, will become reality within the next 5 to 10 years.

Nucleic acids (DNA and RNA) have been detected in plasma, serum, urine, and other body fluids from healthy subjects as well as in patients. The ability to detect and quantitate specific DNA and RNA sequences has opened up the possibility of diagnosis and monitoring of diseases. With the recent developments in the field of circulating nucleic acids the application in the diagnostic field has increased. The recent discovery of epigenetic changes in placental/fetal DNA and the detection of fetal/placental-specific RNAs have made it possible to use this technology in all pregnancies irrespective of the gender of the fetus. With the application of mass spectrometry and other techniques to this field, it is now possible to detect very small amounts of specific DNA in the presence of excess of other nonspecific nucleic acids (e.g., detection of mutations in fetal DNA in the presence of excess of maternal DNA). Circulating nucleic acids have now been shown to be useful in other conditions, such as diabetes mellitus, trauma, stroke, and myocardial infarction. In oncology, detection and monitoring of tumors is now possible by the detection of tumor-derived nucleic acids. In spite of these advances questions regarding the origin and biologic significance of circulating nucleic acids remain to be answered. Furthermore pre-analytical and analytical aspects of this field remain to be standardized.