Measuring aerosols in the operating theatre and beyond using a real-time sensor network.

The ability to measure and track aerosols in the vicinity of patients with suspected or confirmed COVID-19 is highly desirable. At present, there is no way to measure and track, in real time, the sizes, dispersion and dilution/disappearance of aerosols that are generated by airway manipulations such as mask ventilation; tracheal intubation; bronchoscopy; dental and gastro-intestinal endoscopy procedures; or by vigorous breathing, coughing or exercise. We deployed low-cost photoelectric sensors in five operating theatres between surgical cases. We measured and analysed dilution and exfiltration of aerosols we generated to evaluate air handling and dispersion under real-world conditions. These data were used to develop a model of aerosol persistence. We found significant variation between different operating theatres. Equipment placement near air vents affects air flows, impacting aerosol movement and elimination patterns. Despite these impediments, air exchange in operating theatres is robust and prolonged fallow time before theatre turnover may not be necessary. Significant concentrations of aerosols are not seen in adjoining areas outside of the operating theatre. These models and dispersion rates can predict aerosol persistence in operating theatres and other clinical areas and potentially facilitate quantification of risk, with obvious and far-reaching implications for designing, evaluating and confirming air handling in non-medical environments.

Burden of disease study of overweight and obesity; the societal impact in terms of cost-of-illness and health-related quality of life.

BACKGROUND: Little is known about the burden that overweight and obesity impose on Dutch society. The aim of this study is to examine this burden in terms of cost-of-illness and health-related quality of life. METHOD: A bottom-up, prevalence-based burden of disease study from a societal perspective was performed. Cost-of-illness information including healthcare costs, patient and family costs, and other costs was obtained via the Treatment Inventory of Costs in Patients with psychiatric disorders (TiC-P) questionnaire. Health-related quality of life was assessed through the EuroQol (EQ-5D-5L) and the BODY-Q instruments. Non-parametric bootstrapping was applied to test for significant differences in costs. Subgroup analyses were performed on all outcomes. RESULTS: A total of 97 people with overweight and obesity completed the survey. Per respondent, mean healthcare costs were €2907, patient and family costs were €4037, and other costs were €4519, leading to a total societal cost of €11,463 per respondent per year. Total costs were significantly higher for respondents with obesity versus overweight and between low & intermediate versus highly educated respondents. The mean utility score of our population was 0.81. A significantly lower utility score was found for respondents with obesity in comparison with respondents with overweight. BODY-Q results show that respondents with obesity scored a significantly lower Rasch-score than did respondents with overweight in three scales. Respondents with a high education level and having paid work scored significantly higher Rasch-scores in two scales than did those with a low education level and without having paid work. The age group 19-29 have significantly higher Rasch-scores in three scales than respondents in the other two age categories. CONCLUSIONS: Overweight and obesity have a considerable impact on the societal costs and on health-related quality of life. The results show that the impact of overweight and obesity go beyond the healthcare sector, as the other costs have the biggest share of the total costs. Another interesting finding of this study is that obesity leads to significant higher costs and lower health-related quality of life than overweight. These findings draw attention to policy making, as collective prevention and effective treatment are needed to reduce this burden.

The protocadherin 17 gene affects cognition, personality, amygdala structure and function, synapse development and risk of major mood disorders.

Major mood disorders, which primarily include bipolar disorder and major depressive disorder, are the leading cause of disability worldwide and pose a major challenge in identifying robust risk genes. Here, we present data from independent large-scale clinical data sets (including 29 557 cases and 32 056 controls) revealing brain expressed protocadherin 17 (PCDH17) as a susceptibility gene for major mood disorders. Single-nucleotide polymorphisms (SNPs) spanning the PCDH17 region are significantly associated with major mood disorders; subjects carrying the risk allele showed impaired cognitive abilities, increased vulnerable personality features, decreased amygdala volume and altered amygdala function as compared with non-carriers. The risk allele predicted higher transcriptional levels of PCDH17 mRNA in postmortem brain samples, which is consistent with increased gene expression in patients with bipolar disorder compared with healthy subjects. Further, overexpression of PCDH17 in primary cortical neurons revealed significantly decreased spine density and abnormal dendritic morphology compared with control groups, which again is consistent with the clinical observations of reduced numbers of dendritic spines in the brains of patients with major mood disorders. Given that synaptic spines are dynamic structures which regulate neuronal plasticity and have crucial roles in myriad brain functions, this study reveals a potential underlying biological mechanism of a novel risk gene for major mood disorders involved in synaptic function and related intermediate phenotypes.

Evaluation of single-view contrast-enhanced mammography as novel reading strategy: a non-inferiority feasibility study.

BACKGROUND: Guidelines recommend screening of high-risk women using breast magnetic resonance imaging (MRI). Contrast-enhanced mammography (CEM) has matured, providing excellent diagnostic accuracy. To lower total radiation dose, evaluation of single-view (1 V) CEM exams might be considered instead of double-view (2 V) readings as an alternative reading strategy in women who cannot undergo MRI. METHODS: This retrospective non-inferiority feasibility study evaluates whether the use of 1 V results in an acceptable sensitivity for detecting breast cancer (non-inferiority margin, - 10%). CEM images from May 2013 to December 2017 were included. 1 V readings were performed by consensus opinion of three radiologists, followed by 2 V readings being performed after 6 weeks. Cases were considered "malignant" if the final BI-RADS score was ≥ 4, enabling calculation of sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). Histopathological results or follow-up served as a gold standard. RESULTS: A total of 368 cases were evaluated. Mean follow-up for benign or negative cases was 20.9 months. Sensitivity decreased by 9.6% from 92.9 to 83.3% when only 1 V was used for evaluation (p < 0.001). The lower limit of the 90% confidence interval around the difference in sensitivity between 1 V and 2 V readings was - 15% and lies below the predefined non-inferiority margin of - 10%. Hence, non-inferiority of 1 V to 2 V reading cannot be concluded. AUC for 1 V was significantly lower, 0.861 versus 0.899 for 2 V (p = 0.0174). CONCLUSION: Non-inferiority of 1 V evaluations as an alternative reading strategy to standard 2 V evaluations could not be concluded. 1 V evaluations had lower diagnostic performance compared with 2 V evaluations. KEY POINTS: • To lower radiation exposure used in contrast-enhanced mammography, we studied a hypothetical alternative strategy: single-view readings (1 V) versus (standard) double-view readings (2 V). • Based on our predefined margin of - 10%, non-inferiority of 1 V could not be concluded. • 1 V evaluation is not recommended as an alternative reading strategy to lower CEM-related radiation exposure.

Augmentation of Transient Donor Cell Chimerism and Alloantigen-Specific Regulation of Lung Transplants in Miniature Swine.

Donor alloantigen infusion induces T cell regulation and transplant tolerance in small animals. Here, we study donor splenocyte infusion in a large animal model of pulmonary transplantation. Major histocompatibility complex-mismatched single lung transplantation was performed in 28 minipigs followed by a 28-day course of methylprednisolone and tacrolimus. Some animals received a perioperative donor or third party splenocyte infusion, with or without low-dose irradiation (IRR) before surgery. Graft survival was significantly prolonged in animals receiving both donor splenocytes and IRR compared with controls with either donor splenocytes or IRR only. In animals with donor splenocytes and IRR, increased donor cell chimerism and CD4(+) CD25(high+) T cell frequencies were detected in peripheral blood associated with decreased interferon-γ production of leukocytes. Secondary third-party kidney transplants more than 2 years after pulmonary transplantation were acutely rejected despite maintained tolerance of the lung allografts. As a cellular control, additional animals received third-party splenocytes or donor splenocyte protein extracts. While animals treated with third-party splenocytes showed significant graft survival prolongation, the subcellular antigen infusion showed no such effect. In conclusion, minipigs conditioned with preoperative IRR and donor, or third-party, splenocyte infusions may develop long-term donor-specific pulmonary allograft survival in the presence of high levels of circulating regulatory T cells.

Impact of MIC range for Pseudomonas aeruginosa and Streptococcus pneumoniae on the ceftolozane in vivo pharmacokinetic/pharmacodynamic target.

Ceftolozane is a novel cephalosporin with activity against drug-resistant pathogens, including Pseudomonas aeruginosa and Streptococcus pneumoniae. The in vivo investigation reported here tested the limits of this drug against 20 P. aeruginosa and S. pneumoniae isolates across a wide MIC range and defined resistance mechanisms. The times above the MIC (T>MIC) targets for stasis and 1- and 2-log reductions were 31%, 39%, and 42% for P. aeruginosa and 18%, 24%, and 27% for S. pneumoniae, respectively. The 1-log endpoint was achieved for strains with MICs as high as 16 µg/ml.

Assessment of aerosol persistence in ICUs via low-cost sensor network and zonal models.

The COVID-19 pandemic raised public awareness about airborne particulate matter (PM) due to the spread of infectious diseases via the respiratory route. The persistence of potentially infectious aerosols in public spaces and the spread of nosocomial infections in medical settings deserve careful investigation; however, a systematic approach characterizing the fate of aerosols in clinical environments has not been reported. This paper presents a methodology for mapping aerosol propagation using a low-cost PM sensor network in ICU and adjacent environments and the subsequent development of the data-driven zonal model. Mimicking aerosol generation by a patient, we generated trace NaCl aerosols and monitored their propagation in the environment. In positive (closed door) and neutral-pressure (open door) ICUs, up to 6% or 19%, respectively, of all PM escaped through the door gaps; however, the outside sensors did not register an aerosol spike in negative-pressure ICUs. The K-means clustering analysis of temporospatial aerosol concentration data suggests that ICU can be represented by three distinct zones: (1) near the aerosol source, (2) room periphery, and (3) outside the room. The data suggests two-phase plume behavior: dispersion of the original aerosol spike throughout the room, followed by an evacuation phase where "well-mixed" aerosol concentration decayed uniformly. Decay rates were calculated for positive, neutral, and negative pressure operations, with negative-pressure rooms clearing out nearly twice as fast. These decay trends closely followed the air exchange rates. This research demonstrates the methodology for aerosol monitoring in medical settings. This study is limited by a relatively small data set and is specific to single-occupancy ICU rooms. Future work needs to evaluate medical settings with high risks of infectious disease transmission.

An IgE epitope of Bet v 1 and fagales PR10 proteins as defined by a human monoclonal IgE.

BACKGROUND: Analyses of the molecular basis underlying allergenicity and allergen cross-reactivity, as well as improvement of allergy diagnostics and therapeutics, are hampered by the lack of human monoclonal IgE antibodies and knowledge about their epitopes. Here, we addressed the consecutive generation and epitope delineation of a human monoclonal IgE against the prototypic allergen Bet v 1. METHODS: Phage-display scFv hybrid libraries of allergic donor-derived VH epsilon and synthetic VL were established from 107 mononuclear cells. An obtained scFv was converted into human immunoglobulin formats including IgE. Using variants of Bet v 1, the epitope of the antibody was mapped and extrapolated to other PR10 proteins. RESULTS: The obtained antibodies exhibited pronounced reactivity with Bet v 1, but were not reactive with the homologous PR10 protein Mal d 1. The epitope as defined by the IgE paratope and a set of chimeric Bet v 1 fusion proteins and fragments could be assigned to a C-terminal helix-structured motif comprised by amino acid residues 132-154, including the critical residue E149. Grafting this motif re-established the reactivity of the per se nonreactive Mal d 1 framework. Cross-reactivities predicted by primary structure analyses of different isoforms and PR10 proteins were verified by allergen chip-based analyses. CONCLUSIONS: The obtained results demonstrate that hybrid IgE repertoires represent a source for human antibodies with genuine paratopes. The IgE-derived information about the IgE epitope nature of Bet v 1 and homologues allows for detailed insights into molecular aspects of allergenicity and cross-reactivity within the PR10 protein family.

The effects of Hurricane Irma on seagrass meadows in previously eutrophic estuaries in Southwest Florida (USA).

In six contiguous estuaries in Southwest Florida (USA) focused management actions over the past several decades have reduced watershed nutrient loads, resulting in an additional 11,672 ha of seagrass meadows between 1999 and 2016, an improvement of 32%. However, in September of 2017, Hurricane Irma made landfall in the state of Florida, affecting the open water and watersheds of each of these six estuaries. In response, seagrass coverage declined by 1203 ha between 2016 and 2018, a system-wide decrease of 3%. The range of decreases associated with Hurricane Irma varied from less than a 1% loss of seagrass coverage in St. Joseph Sound to declines of 7 and 11% in Clearwater Harbor and Lemon Bay, respectively. Areas with the largest losses between 2016 and 2018 were those systems where seagrass coverage had declined in prior years, indicating the effects of Hurricane Irma might have been intensified by prior impacts.

Widespread recovery of seagrass coverage in Southwest Florida (USA): Temporal and spatial trends and management actions responsible for success.

In Southwest Florida, a variety of human impacts had caused widespread losses of seagrass coverage from historical conditions. St. Joseph Sound and Clearwater Harbor lost approximately 24 and 51%, respectively, of their seagrass coverage between 1950 and 1999, while Tampa Bay and Sarasota Bay had lost 46% and 15%, respectively, of their seagrass coverage between 1950 and the 1980s. However, over the period of 1999 to 2016, the largest of the six estuaries, Tampa Bay, added 408 ha of seagrass per year, while the remaining five estuaries examined in this paper added approximately 269 ha per year. In total, seagrass coverage in these six estuaries increased 12,171 ha between the 1980s and 2016. Focused resource management plans have held the line on nitrogen loads from non-point sources, allowing seagrass resources to expand in response to reductions in point source loads that have been implemented over the past few decades.

A 24-week, randomized, double-blind study of donepezil in moderate to severe Alzheimer's disease.

OBJECTIVE: To investigate the efficacy and safety of donepezil in patients with moderate to severe AD (standardized Mini-Mental State Examination [sMMSE] scores of 5 to 17; Functional Assessment Staging score < or =6 at baseline). METHODS: Two-hundred ninety patients were randomized to treatment in this 24-week, double-blind, placebo-controlled trial. Patients received either donepezil 5 mg/day for the first 28 days and 10 mg/day thereafter as per the clinician's judgment (n = 144) or placebo (n = 146). The primary outcome measure was the Clinician's Interview-Based Impression of Change with caregiver input (CIBIC+). RESULTS: Patients' mean age was 73.6 years (range 48 to 92 years). Baseline demographics were similar between the treatment groups. Least squares (LS) mean +/- SE sMMSE scores at baseline were 11.7 +/- 0.35 for the donepezil group and 12.0 +/- 0.34 for the placebo group. Patients receiving donepezil showed benefits on the CIBIC+, compared with placebo, at all visits up to week 24 (p < 0.001) and at week 24 last observation carried forward (LOCF) (p < 0.0001). All other secondary measures (including sMMSE, Severe Impairment Battery, Disability Assessment for Dementia, Functional Rating Scale, and Neuropsychiatric Inventory) showed significant differences between the groups in favor of donepezil at week 24 LOCF. Eighty-four percent of donepezil- and 86% of placebo-treated patients completed the trial. Adverse events (AE) were experienced by 83% of donepezil- and 80% of placebo-treated patients, the majority of which were rated mild in severity; 8% of donepezil- and 6% of placebo-treated patients discontinued because of AE. Laboratory and vital sign abnormalities were similar between the treatment groups. CONCLUSION: These data suggest that donepezil's benefits extend into more advanced stages of AD than those previously investigated, with very good tolerability.

Cytomegalovirus early promoter induced expression of hCD59 in porcine organs provides protection against hyperacute rejection.

The critical shortage of human donor organs has generated growing interest for porcine to human xenotransplantation. The major immunological barrier to xenotransplantation is the hyperacute rejection (HAR) response that is mediated by preformed xenoreactive antibodies and complement. A promising strategy to control the complement activation, is the expression of human complement regulatory proteins in transgenic animals. We have used the human early cytomegalovirus (CMV) promoter to drive expression of the human complement regulatory protein CD59 (hCD59) in transgenic pigs. A total of eight live transgenic founder animals was born from which five transgenic lines could be established. mRNA analysis and Western blotting revealed high expression of hCD59 in heart, kidney, skeletal muscle, and skin in animals of lines 1 and 5, as well as in the pancreas of four lines. This pattern of expression was confirmed by immunhistological staining. A cell-specific expression in heart and kidney tissue of transgenic lines 1 and 5 was determined. Primary fibroblasts and endothelial cell cultures derived from the aorta of transgenic pigs showed a significantly diminished sensitivity against the challenge with xenoreactive human antibodies and complement whereas non-transgenic control cells were highly susceptible to complement mediated lysis. Ex vivo perfusion of kidneys with pooled human blood revealed a significant protective effect of hCD59 against HAR. The average survival of transgenic kidneys was significantly extended (P<0.05) over nontransgenic controls (207.5+/-54.6 vs. 57.5+/-64.5 min). These data support the concept that hCD59 protects nonprimate cells against human complement mediated lysis and suggest that donor pigs transgenic for hCD59 could play a crucial role in clinical xenotransplantation. Two of five hCD59 transgenic lines showed strong hCD59 expression in several organs relevant for xenotransplantation and a protective effect against HAR. This indicates that the use of the CMV-promoter can facilitate the selection process for optimized transgene expression.

Thrombogenicity of tips of umbilical catheters.

In an experiment in which several types of umbilical artery catheters were inserted into the aortas of newborn lambs, several catheters had discrete thrombi located at the tip. There appeared to be a difference between types of catheters in the proportion with thrombi at the tip. Scanning electron micrographs of catheter tips showed that several types had rough tips. It is suggested that a rough tip would promote the formation of thrombus at a location where it could be dislodged by flushing of the catheter. The problems that have been reported with umbilical artery catheters may have been caused by thrombus at the tip rather than on the shaft of these catheters.

Functional, cognitive and behavioral effects of donepezil in patients with moderate Alzheimer's disease.

OBJECTIVE: To investigate the efficacy and safety of donepezil in a subgroup of patients with Alzheimer's disease (AD) of moderate severity from a previous trial. METHODS: Two hundred and seven patients with moderate AD (standardized Mini-Mental State Examination [sMMSE] score 10-17) were randomized to treatment in this 24-week, double-blind, placebo-controlled trial. Patents received either donepezil, 5 mg/day for the first 28 days and 10 mg/day thereafter according to the clinician's judgement (n = 102), or placebo (n = 105). The primary outcome measure was the Clinician's Interview-Based Impression of Change with caregiver input (CIBIC-plus) at week 24 using a last observation carried forward (LOCF) analysis. RESULTS: Baseline patient demographics were similar between treatment groups. Mean age was 74.3 years (range 48-92). Least-squares (LS) mean sMMSE scores at baseline were 13.6 +/- 0.3 for the donepezil group and 13.9 +/- 0.3 for the placebo group. LS mean CIBIC-plus scores for donepezil-treated patients were improved from, or close to, baseline severity at all visits, and were significantly different from placebo at weeks 8, 12, 18, and 24 (week 24 LOCF mean difference = 0.53, p = 0.0003). LS mean change from baseline scores on the sMMSE and Severe Impairment Battery (SIB) for the donepezil group improved throughout the study, and were significantly different from placebo at each visit for the sMMSE (week 24 LOCF mean difference = 2.06, p = 0.0002) and from week 8 for the SIB (week 24 LOCF mean difference = -4.44, p = 0.0026). LS mean change scores on the Disability Assessment for Dementia remained at or above baseline levels throughout the study for the donepezil group, while the placebo group showed a steady decline; treatment differences were significant at each visit (week 24 LOCF mean difference = -9.25, p < 0.0001). LS mean change scores on the Neuropsychiatric Inventory 12-item total improved throughout the study for the donepezil group and were significantly different from placebo at weeks 4 and 24 (week 24 LOCF mean difference = 5.92, p = 0.0022). Eighty-one per cent of donepezil-treated and 89% of placebo-treated patients completed the trial, with 9% and 5%, respectively, discontinuing due to adverse events (AEs). Eighty-two per cent of donepezil-treated and 80% of placebo-treated patients experienced AEs, the majority of which were rated mild in severity and, in general, were similar between treatment groups. CONCLUSION: The significant treatment responses observed with donepezil in these patients reinforce the findings from earlier studies that show donepezil to have important benefits, compared wih placebo, across functional, cognitive, and behavioral symptoms, with good tolerability, in patients with AD of moderate severity.

Self-directed treatment with minimal therapist contact: preliminary findings for obsessive-compulsive disorder.

The efficacy of a brief intervention for obsessive-compulsive disorder (OCD) was examined with nine clients. Treatment consisted of five meetings with the therapists, readings from When once is not enough (Steketee & White, 1990), and self-directed exposure with response prevention. The self-report version of the Yale-Brown Obsessive-Compulsive Scale was the primary dependent measure. Participants who received treatment after a 6-week delay showed stability of severity of OCD over the waiting period. As a group, participants showed statistically significant improvement on the main outcome measures. One-third of the clients met criteria for clinically significant improvement indicating that some individuals suffering with OCD can be helped with a brief intervention.

Effects of low-dose heparin on failure of intravenous infusions in children.

OBJECTIVE: To determine if a dextrose-saline solution manufactured under commercial conditions and containing 1 IU per ml of heparin prolongs the use of infusion sites in children. DESIGN: Double-blind randomized trial. PATIENTS: Eighty children in a medical ward. OUTCOME MEASURES: Failure of infusion sites from phlebitis and/or extravasation. INTERVENTION: Duration of use of infusion sites was calculated to the nearest hour. STATISTICS: Univariate survival analysis. RESULTS: The median time to failure when solutions contained the heparin (97 hours) was significantly increased (p < 0.0001) compared with control solutions (43 hours). CONCLUSIONS: Use of solutions containing low-dose heparin is recommended for children who might have problems with venous access.

The possible function of positive reinforcement in home-bound agoraphobia: a case study.

We conducted an uncontrolled case study (ABA design) based upon the hypothesis that the behavior of a home-bound agoraphobic is at least partially maintained by positive reinforcement in the home and that a disruption of access to home-based reinforcement would lead to an increased frequency of out-of-the-home behavior. Data concerning the types and amounts of behavior engaged in by the subject within the confines of her home and yard were gathered during a 30-day base line period. In addition, potential reinforcers in the home were identified by a survey schedule and by self-report of time allocation. During an 18-day intervention period the subject agreed only to engage in certain reinforcing activities outside her home (e.g., only watching television at a neighbor's house). Postintervention results indicated that for the first time in over 7 years the subject began engaging in out-of-home activities, including walking to other parts of the street, visiting several neighbors' homes, and attending parties at neighbors' homes. Moreover, data suggested a positive trend in time spent outside the yard during both 2 and 18 month follow-up periods. However, significant restrictions in the range of mobility were still observed.

Hemotympanums secondary to spontaneous epistaxis.

Three cases of hemotympanum that resulted from spontaneous, atraumatic epistaxis are presented. Hemotympanum is a well known physical finding associated with traumatic basilar skull fractures but has not been reported to follow spontaneous nose bleeds that have not been previously treated with nasal packing. A discussion of epistaxis and hemotympanum is presented, and their implication for emergency physicians is discussed.

Pulmonary embolism complicated by patent foramen ovale and paradoxical embolization.

We present the case of a 74-year-old male with chest pain, dyspnea, and syncope secondary to an acute pulmonary embolism complicated by a patent foramen ovale with straddling thrombus and paradoxical embolization. We review the literature with specific focus on the pathogenesis and acute treatment of this life-threatening occurrence.

Lipid-mediated delivery of RNA is more efficient than delivery of DNA in non-dividing cells.

The design of appropriate gene delivery systems is essential for the successful application of gene therapy to clinical medicine. Cationic lipid-mediated delivery is a viable alternative to viral vector-mediated gene delivery in applications where transient gene expression is desirable. However, cationic lipid-mediated delivery of DNA to post-mitotic cells such as neurons is often reported to be of low efficiency, due to the presumed inability of the DNA to translocate to the nucleus. Lipid-mediated delivery of RNA is an attractive alternative to non-viral DNA delivery in some clinical applications, because transit across the nuclear membrane is not necessary. Here we report a comparative investigation of cationic lipid-mediated delivery of RNA versus DNA vectors encoding the reporter gene green fluorescent protein (GFP) in Chinese Hamster Ovary (CHO) and NIH3T3 cells following chemical inhibition of proliferation, and in primary mixed neuronal cell cultures. Using optimized formulations and transfection procedures, we assess gene expression by flow cytometry to specifically address some of the advantages and disadvantages of lipid-mediated RNA and DNA gene transfer. Despite inhibition of cell proliferation, over 45% of CHO cells express GFP after lipid-mediated transfection with RNA vectors. Transfection efficiency of DNA encoding GFP in proliferation-inhibited CHO cells was less than 5%. Detectable expression after RNA transfection occurs at least 3h earlier than after DNA transfection, but DNA transfection eventually produces a mean level of per cell GFP expression (as assayed by flow cytometry) that is higher than after RNA transfection. Transfection of proliferation-inhibited NIH3T3 cells and primary mixed neuronal cultures produced similar results, with RNA encoded GFP expression in 2-4 times the number of cells as after DNA encoded GFP expression. These results demonstrate the increased efficiency of RNA transfection relative to DNA transfection in non-dividing cells. We used firefly luciferase encoded by RNA and DNA vectors to investigate the time course of gene expression after delivery of RNA or DNA to primary neuronal cortical cells. Delivery of mRNA resulted in rapid onset (within 1h) of luciferase expression after transfection, a peak in expression 5-7h after transfection, and a return to baseline within 12h after transfection. After DNA delivery significant luciferase activity did not appear until 7h after transfection, but peak luciferase expression was always at least one order of magnitude higher than after RNA delivery. The peak expression after luciferase-expressing DNA delivery occurred 36-48 h after transfection and remained at a significant level for at least one week before dropping to baseline. This observation is consistent with our in vivo delivery results, which are shown as well. RNA delivery may therefore be more suitable for short-term transient gene expression due to rapid onset, shorter duration of expression and greater efficiency, particularly in non-dividing cells. Higher mean levels of expression per cell obtained following DNA delivery and the longer duration of expression confirm a continuing role for DNA gene delivery in clinical applications that require longer term transient gene expression.