The effectiveness of interventions to reduce peripheral blood culture contamination in acute care: a systematic review protocol

BACKGROUND

Blood cultures are an integral part of the diagnosis of bacteremia in unwell patients. The treatment of bacteremia involves the rapid and accurate identification of the causative agent grown from the blood cultures collected. Contamination of blood cultures with non-pathogenic microbes such as skin commensals causes false positive results and subsequent unnecessary and potentially harmful interventions. While guidelines for blood culture quality recommend no more than 2-3% contamination rate, rates up to 12% are reported in the literature. There have been a number of methods proposed to reduce the contamination of blood cultures, including educational interventions, changing of skin cleansing preparations and introduction of blood culture collection packs in acute care settings. This protocol outlines methods to identify and evaluate interventions to reduce blood culture contamination in the acute care setting.

METHODS

The reviewers will conduct a systematic search of literature in CINHAL, PubMed, EMBASE and the Cochrane Central register of controlled trials. Unpublished works will be identified in ProQuest Dissertations and Theses. Articles will be assessed for relevance based on their title and abstract. Remaining relevant citations will have their full text retrieved and assessed against eligibility criteria. All studies that meet the eligibility criteria will have their methodological quality appraised. Assessments for relevance and methodological quality will be conducted independently by two reviewers. If appropriate, data will be analysed using the Mantel-Haenszel method under a random effects model. Heterogeneity of the studies will be assessed using the I 2 and chi-squared statistic. Meta-analysis will be attempted if the data is suitable.

DISCUSSION

This review will identify and summarise the interventions previously described in the literature aimed at reducing peripherally collected blood culture contamination rates in acute care. These findings have the potential to lead to multifaceted interventions based on previous evidence to reduce blood culture contamination in the acute setting. Reductions in the proportion of contaminated blood cultures have the potential to save money, unrequired treatment (particularly antimicrobials) and hospital bed days.

SYSTEMATIC REVIEW REGISTRATION

In accordance with guidelines outlined in the PRISMA-P methodology, this protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on December 8, 2017, and last updated on January 4, 2018 (registration number CRD42017081650).

Anatomical variation in the position of the brachiocephalic trunk (innominate artery) with respect to the trachea: a computed tomography-based study and literature review of Innominate Artery Compression Syndrome

Respiratory compromise due to tracheal compression by the brachiocephalic trunk (BT), a condition first labeled as Innominate Artery Compression Syndrome (IACS), has been controversially attributed to an anomalous origin of this vessel to the left of, and hence crossing, the trachea. The aim of this study was to establish the normal relationship between the BT and trachea in infants, children, and young adults without obstructive respiratory symptoms. One hundred and eighty-one computed tomography (CT) examinations of the thorax, in three age groups, were reviewed. In axial cross section, the origin of the BT from the aortic arch was identified. The BT origin, with respect to the trachea, was recorded as for a clock face, approximated to the nearest half hour. There were 62 CTs in Group 1 (1 day to 3 years of age), 48 CTs in Group 2 (10-15 years), and 71 examinations in Group 3 (20-40 years). In 96.8% of Group 1, 91.7% of Group 2, and 74.6% of Group 3 the BT origin was to the left of the trachea, between the half past twelve and 3 o'clock positions. The BT origin occurred more the left in Group 1 when compared with the other two groups (P < 0.001). An origin of the BT to the left of the trachea is a normal finding in children and young adults without obstructive respiratory symptoms. There is a tendency for the origin to become progressively more rightward with age.

Ocean fertilization: a potential means of geoengineering?

The oceans sequester carbon from the atmosphere partly as a result of biological productivity. Over much of the ocean surface, this productivity is limited by essential nutrients and we discuss whether it is likely that sequestration can be enhanced by supplying limiting nutrients. Various methods of supply have been suggested and we discuss the efficacy of each and the potential side effects that may develop as a result. Our conclusion is that these methods have the potential to enhance sequestration but that the current level of knowledge from the observations and modelling carried out to date does not provide a sound foundation on which to make clear predictions or recommendations. For ocean fertilization to become a viable option to sequester CO2, we need more extensive and targeted fieldwork and better mathematical models of ocean biogeochemical processes. Models are needed both to interpret field observations and to make reliable predictions about the side effects of large-scale fertilization. They would also be an essential tool with which to verify that sequestration has effectively taken place. There is considerable urgency to address climate change mitigation and this demands that new fieldwork plans are developed rapidly. In contrast to previous experiments, these must focus on the specific objective which is to assess the possibilities of CO2 sequestration through fertilization.

The alpha7 nicotinic receptor agonist 4OH-GTS-21 protects axotomized septohippocampal cholinergic neurons in wild type but not amyloid-overexpressing transgenic mice

While activation of alpha7 nicotinic receptors protects neurons from a variety of apoptotic insults in vitro, little is known about this neuroprotective action in vivo, especially under amyloidogenic conditions that mimic Alzheimer's disease. We therefore investigated the effects of 4OH-GTS-21, a selective partial agonist for these receptors, on septohippocampal cholinergic and GABAergic neuron survival following fimbria fornix (FFX) lesions in three strains of mice: C57BL/6J wild type mice; human presenilin-1 mutant M146L (PS1) transgenic mice; and mice expressing both mutant PS1 and Swedish mutant K670N/M671L amyloid precursor protein (APP). Initial studies to demonstrated that 4OH-GTS-21 is likely brain permeant based on its ability to improve passive avoidance and Morris water task behaviors in nucleus basalis-lesioned rats. In FFX-lesioned mice, twice per day i.p. injections of 1 mg/kg of 4OH-GTS-21 for 2 weeks promoted the survival and prevented the atrophy of septal cholinergic neurons. Septal parvalbumin-staining GABAergic neurons were not protected by this treatment, although they also express alpha7 nicotinic receptors, suggesting an indirect, nerve growth factor (NGF)-mediated mechanism. No protection of cholinergic neurons was observed in similarly treated PS1 or APP/PS1 transgenic mice. 4OH-GTS-21 treatment actually reduced cholinergic neuronal size in APP/PS1 mice. Hippocampal amyloid deposition was not affected by FFX lesions or treatment with this alpha7 nicotinic receptor agonist in APP/PS1 mice under these conditions. These results indicate that brain alpha7 nicotinic receptors are potential targets for protecting at-risk brain neurons in Alzheimer's disease, perhaps via their effects on NGF receptors; however, this protection may be sensitive under some conditions to environmental factors such as inhibitory amyloid-peptides.

alpha7 Nicotinic receptor gene delivery into mouse hippocampal neurons leads to functional receptor expression, improved spatial memory-related performance, and tau hyperphosphorylation

Brain alpha7 nicotinic receptors have become therapeutic targets for Alzheimer's disease (AD) based on their memory-enhancing and neuroprotective actions. This study investigated the feasibility of increasing neuronal alpha7 receptor functions using a gene delivery approach based on neuron-selective recombinant adeno-associated virus (rAAV)-derived vectors. In order to determine whether alpha7 receptor-mediated cytotoxicity was dependent on receptor density, rat alpha7 nicotinic receptors were expressed at high concentrations in GH4C1 cells as measured with nicotine-displaceable [3H]methyllycaconitine (MLA) binding. The potency of GTS-21 (an alpha7 receptor agonist) to induce cell loss was similar in these cells to that seen in pheochromocytoma (PC12) cells expressing nine-times-lower receptor levels, suggesting that cytotoxicity was more dependent on agonist concentration than receptor density. Hippocampal transduction with rat alpha7 nicotinic receptors increased [3H]MLA binding in this region in wild type and alpha7 receptor-knockout (KO) mice without apparent cytotoxicity. No difference was observed in Kd values for MLA binding between endogenous and transgenic receptors. Single cell recordings demonstrated that dentate granule cells that normally have no alpha7 receptor response did so following alpha7 receptor gene delivery in wild type mice. Recovery of alpha7 function was also observed in stratum oriens and stratum radiatum neurons of KO mice following gene delivery. Wild type mice exhibited improved acquisition performance in the Morris water task 1 month after bilateral hippocampal transductions with the rat alpha7 receptor gene compared with green fluorescent protein-transduced controls. However, both groups reached similar training levels and there was no difference in subsequent probe performance. Finally, this gene delivery approach was used to test whether alpha7 receptors affect tau-phosphorylation. Chronic (i.e. 2 month but not 2 week) expression of high levels of alpha7 receptors in hippocampus increased AT8 staining characteristic of hyperphosphorylated tau in that region, indicating that endogenous agonist-mediated receptor activation may be able to modulate this process.

The relationship between enamel softening and erosion caused by soft drinks at a range of temperatures

OBJECTIVES

Investigations of the erosive potential of soft drinks are usually performed at room or body temperature, but drinks are more frequently served chilled, with ice, or hot. Since the rate of chemical reactions usually increases with temperature, it is predicted that erosion is more severe at high temperatures and reduced at low temperatures. The aim of this study was to investigate the correlation between enamel softening, enamel erosion, and temperature.

METHODS

Atomic force microscopy nanoindentation and non-contact optical profilometry were used to assess changes in enamel nanomechanical properties after 5 min and erosive material loss after 30 min exposure to two different non-carbonated soft drinks at 4, 25, 50 and 75 degrees C.

RESULTS

For one drink (Robinson's Original Juice Drink), there was a statistically significant difference between nanomechanical properties and erosion depth at all temperatures, with softening and erosion increasing with temperature. For another drink (Ribena ToothKind Juice Drink), there was a slight softening and virtually no material loss, and temperature had no statistically significant impact on erosion. There was a good linear correlation (R2 = 0.94) between nanomechanical properties and material loss.

CONCLUSIONS

The difference between the drinks can be explained by their composition. For the erosive drink, material loss increased, and nanohardness decreased, approximately linearly with temperature. The correlation between softening and erosion demonstrated that nanomechanical properties after very short erosion times can be considered a good predictor of bulk material loss after considerably longer erosion times.

A methodology for testing the erosive potential of sports drinks

OBJECTIVES

The aim of the study was to develop and test a methodology in situ, which simulated the consumption of sports drinks. A secondary aim was to assess the acceptability of the method to sedentary participants.

METHODS

To select the sports drink for the study in situ, five commercially available sports drinks were examined for erosive potential in vitro. The study in situ was a single centre, 2-period, 2-treatment crossover study to compare the erosive effect of a commercially available sports drink (Test), with that of mineral water (Control), over 10 day periods on 10 healthy volunteers. Subjects wore upper removable appliances containing two human enamel specimens from 9 a.m. to 5 p.m. The regimen of intake of the drinks was 350 ml in 10, 5-min rest, 650 ml in 25, 5-min rest, 500 ml in 10 and 5-min rest. Measurements of enamel loss were made on samples after 5 and 10 days by profilometry.

RESULTS

The in situ study showed a statistically significant difference in erosive potential between the test and control beverages. No specimen exposed to the control beverage displayed appreciable erosion. Erosion occurred with the test drink, but to a variable degree between subjects. The subjects unanimously found the drinking regimen unpleasant.

CONCLUSIONS

The sports drink caused significantly more erosion in situ than water and as seen in other studies, there was marked variation in susceptibility to erosion between subjects. The new drinking regimen was designed to simulate pre, during and post-exercise intake. Although all the sedentary subjects participating in this study reported that they found the volume of fluids consumed over a short period of time excessive it is unlikely that this would prove problematic in the exercise environment.

Modification of soft drinks with xanthan gum to minimise erosion: a study in situ

OBJECTIVE

To compare the erosive effect of a new blackcurrant/calcium drink with xanthan gum, on enamel in situ, with a low erosive product, a conventional fruit beverage and water.

DESIGN

The study was single centre, randomised, single blind, 4 treatment crossover design.

SETTING

This study, conducted in 2000, employed volunteers working at the Bristol Dental Hospital, UK.

SUBJECTS, MATERIALS AND METHODS

16 subjects (>or=18 years) wore two enamel samples in a removable acrylic appliance. The drinks tested were (A) New blackcurrant/calcium/gum drink (test product), (B) Original blackcurrant/calcium drink, (C) Conventional blackcurrant drink (positive control) and (D) Water (negative control), for 15 day study periods. Drinking was supervised, with 250 ml imbibed four times/day between 9.00am-5.00pm. Profile measurements of specimens were made at baseline, 5, 10 and 15 days.

MAIN OUTCOME MEASURES

Paired t-tests compared erosion by surfometry with selected pairs of formulations.

RESULTS

Of 16 screened subjects (3 male, 13 female), mean age 34.2 years, 1 subject failed to complete the study. A caused significantly less enamel loss than C, with no statistically significant differences from B at any time points measured. Of 43 treatment emergent adverse events, none were considered related to the study formulations.

CONCLUSIONS

A retained low erosive properties similar to B, with additional benefits of taste flexibility and beverage stability.

The protective effect of fluoride treatments against enamel erosion in vitro

Fluoride is known to reduce enamel solubility during the caries process. The aim of this investigation was to determine whether fluoride preparations affect erosion attributed to citric acid and citric acid-based soft drinks. Flat enamel specimens embedded in epoxy resin were prepared from caries free, human third molar teeth extracted from patients aged 18-35 years. Specimens were polished to have a profile within a tolerance of +/-0.3 microm measured on a profilometer. Specimens were taped to leave a 2 mm window of exposed enamel. Groups of specimens were exposed to citric acid and soft drinks with and without the addition of sodium fluoride or exposed to the same solutions after pre-treatment with fluoride products. Enamel loss was measured by profilometer after 10, 20 and 30 min of acid exposure. The different acidic solutions varied significantly in the amount of erosion produced both with and without the addition of fluoride. In addition, the different fluoride products differed significantly in the protective effect afforded. Both fluoride application methods reduced in mean terms, enamel erosion at all time points and by all acidic solutions. The majority of differences were <25% and as the study was powered to show differences as significant at or above this level few reached statistical significance. Fluoride applied to enamel either in acidic solutions or as a pre-treatment, reduces enamel erosion; however, the actual clinical benefit appears low. More studies are required, including investigations in situ.

Cutaneous haemangioma: prevalence and sonographic characteristics of associated hepatic haemangioma

AIMS

To determine the prevalence of hepatic haemangiomas (HH) occurring with multiple or large cutaneous haemangiomas (CH), and compare the ultrasound (US) characteristics of HH with morphology of concurrent CH.

MATERIALS AND METHODS

Retrospective and prospective sonographic and clinical analysis was undertaken on 69 patients referred for US to exclude silent HH. This comprised 62 patients referred over 6 years with six or more CH or one large CH (#10878;5 cm) and seven patients referred over 1 year with three to five small CH.

RESULTS

HH occurred in 45% miliary CH and 40% mixed small and large CH, but also in 12-14% of patients with one large or three or more small CH. None had HH progression. There was association between HH sonographic characteristics and CH number and morphology.

CONCLUSION

Clinically silent HH occurred in nearly one in four of infants presenting overall with six or more small CH or large CH. Previous studies have documented HH mortality between 18 and 80%, although this was not shown in our study. Therefore, if clinical suspicion exists, US is indicated to enable early steroid treatment if significant HH are present.

Development of low erosive carbonated fruit drinks 2. Evaluation of an experimental carbonated blackcurrant drink compared to a conventional carbonated drink

OBJECTIVE

Previous studies demonstrated that a non-carbonated blackcurrant juice drink with added calcium produced little erosion of enamel in vitro and in situ by comparison with other low pH fruit drinks. The aim of this study is to evaluate the erosive effects in situ of an experimental formulation carbonated drink with added calcium, compared to a conventional carbonated drink over a 20 day period using a similar design as in previous studies.

METHOD

The study was a single centre, single blind, randomised placebo controlled three cell crossover design involving 15 volunteers. The test drinks were an experimental carbonated ready-to-drink (RTD) blackcurrant drink, a conventional carbonated RTD orange drink and water. Two enamel samples were retained in situ, in the midline of the hard palate on an upper removable acrylic appliance. Drinks were 250 ml volumes consumed four times per day during 20 working days. Measurements of enamel loss were made on enamel samples after days 2, 5, 10, 15 and 20 by profilometry.

RESULTS

The experimental carbonated blackcurrant drink caused significantly less enamel loss than the conventional carbonated orange drink at all time points measured, but was not significantly different from water at days 2, 5 and 20.

CONCLUSIONS

This study has shown that it is possible to modify carbonated soft drinks in a manner similarly shown with non-carbonated soft drinks, to minimise dental erosion.

Development of low erosive carbonated fruit drinks. 1. Evaluation of two experimental orange drinks in vitro and in situ

OBJECTIVES

To determine the in vitro erosive potential and in situ erosive effect of two new formulation low calorie carbonated orange drinks with that of two conventional diet products and water.

METHODS

In the in vitro study, six specimens of deciduous and permanent enamel were randomly allocated to each of the five products and a '4h' protocol employed. In the in situ study, 15 healthy volunteers participated in a single centre, single blind, 5-phase crossover study, conducted according to Good Clinical Practice, and employing a validated model.

RESULTS

The in vitro erosive potential of the experimental formulations was less than that of the comparators at all time points. Conversely, the observed erosive potential of both experimental formulations was greater than that of the control. Consistent statistically significant differences were found in relation to permanent enamel only. Unfortunately, the in situ study did not produce results entirely consistent with those of the in vitro study. Notably, a generally progressive loss of enamel was observed in specimens exposed to the control.

CONCLUSIONS

The data from the in vitro study show the experimental formulations to have low comparative erosivity. However, the methodologies in vitro and in situ somewhat unusually do not correlate in ranking the erosivity of drinks. The results of this study should therefore be viewed with caution, further research being clearly warranted.

Evaluation of spinal ultrasound in spinal dysraphism

AIMS

The aims of this study were to evaluate the role of spinal ultrasound in detecting occult spinal dysraphism (OSD) in neonates and infants, and to determine the degree of agreement between ultrasound and magnetic resonance imaging (MRI) findings.

MATERIALS AND METHODS

Eighty-five consecutive infants had spinal ultrasound over 31 months. Of these, 15 patients (age 1 day-7 months, mean 40 days; nine male) had follow-up MRI. Ultrasound and MRI findings were correlated retrospectively.

RESULTS

Six out of 15 (40%) ultrasound examinations showed full agreement with MRI, seven of 15 (47%) had partial agreement, and two of 15 (13%) had no agreement. In the present series ultrasound failed to visualize: four of four dorsal dermal sinuses, three of four fatty filum terminales, one of one terminal lipoma, two of four partial sacral agenesis, three of four hydromyelia and one of 10 low-lying cords.

CONCLUSION

Agreement between ultrasound and MRI was good, particularly for the detection of low-lying cord (90%). Therefore we recommend ultrasound as a first-line screening test for OSD. If ultrasound is abnormal, equivocal or technically limited, MRI is advised for full assessment.

Plasmid delivery in the rat brain

Neurodegenerative diseases as a class do not have effective pharmacotherapies. This is due in part to a poor understanding of the pathologies of the disease processes, and the lack of effective medications. Gene delivery is an attractive possibility for treating these diseases. For the paradigm to be effective, efficient, safe and versatile vectors are required. In this study we evaluated three plasmid delivery systems for transgene expression in the rat hippocampus. Two of these systems were designed to have enhanced intracellular biodegradability. It was hypothesized that this system would be less toxic and could increase the free (non-vector) associated plasmids within the cell, leading to increased transgene activity. Polyethylenimine (PEI) and r-AAV-2 (recombinant adeno associated virus-2) were used as positive, non-viral and viral controls respectively, in the in vivo experiments. The results from the studies indicate there is a distinct difference between the various vectors in terms of total cells transfected, type of cell transfected, and toxicity. Non-viral systems were effective at transfecting both neurons and glia cells within the hippocampus, while the r-AAV-2 transfected mainly neurons. In summary, plasmid-mediated systems are effective for transgene expression within the brain and deserve further study.

Dentine hypersensitivity: the effects of brushing toothpaste on etched and unetched dentine in vitro

Although many people have exposed dentine, only a percentage exhibit symptoms of dentine hypersensitivity. This has been ascribed to opening and closing of the dentinal tubules by for example, smear layer changes or tubular occlusion. The aims of this study were to examine the surface morphological changes of etched and unetched dentine in vitro, attributed to the effects of toothbrushing with and without toothpastes designed for the alleviation of dentine hypersensitivity. A total of 96 etched and 96 unetched human dentine specimens were brushed with various toothpastes and water for 1, 2, 5 or 10-min periods in a toothbrushing machine and subsequently examined under scanning electron microscopy for surface changes. Analyses of brushed etched specimens demonstrated that time and treatment were significant variables (P < 0.05) for tubule occlusion. Further, the interaction between time and treatment was significant (P < 0.05). The artificial silica based paste was significantly better for all time intervals at occluding the dentine tubules. All toothpastes investigated caused dynamic changes to the smear layer of the unetched dentine, opening tubules. However, the artificial silica based paste resulted in occluded rather than patent tubules. All of the pastes evaluated had the capacity to remove the smear layer but some could then occlude tubules through the contained abrasives.

Further modification to soft drinks to minimise erosion. A study in situ

Soft drinks have been successfully modified to reduce enamel erosion. The aim of this study was to further modify an original low erosive blackcurrant drink product by the addition of a gum, to manipulate more favourably other drink parameters. The study was a single-blind, randomised four treatment crossover design involving 12 healthy volunteers. During 10 working-day study periods, subjects wore enamel samples in the mid palatal region of a removable appliance. Specimens were taped to expose a 2-mm enamel window. The drinks under test were: (1) Orange juice, (2) Original blackcurrant drink, (3) Water, and (4) Experimental blackcurrant drink. Drinks were imbibed at 250-ml volumes 4 times a day during appliance wearing from 09.00 to 17.00. Appliances were removed at lunchtime. Measurements of specimens were made at baseline, 2, 5 and 10 days using a profilometer. One 5-day and one 10-day specimen from each subject during each treatment were ultrasonicated. Significant differences, in erosion between drinks, were seen at days 5 and 10. Comparisons of preselected pairs of drinks of interest showed significantly reduced erosion by the two blackcurrant drinks compared to orange juice with no significant differences from water. The original blackcurrant drink produced significantly less erosion than the experimental drink. Ultrasonication removed enamel from the Orange juice specimens but very little from those exposed to water and the two blackcurrant drinks. Extrapolating the effects of both blackcurrant drinks suggested that alone they should not cause significant clinical erosion in a lifetime's intake of 1 litre per day.

The effect of pH on the erosion of dentine and enamel by dietary acids in vitro

The reported incidence of tooth erosion caused by acidic soft drinks has been increasingly documented. Citric and phosphoric acids are the two main dietary acids present in these soft drinks. Many variables need to be determined in order to assess risk factors for dental erosion caused by beverage consumption including pH, titratable acidity, pKa, buffering capacity, hence the aim of these in vitro investigations. Methodologies included profiling flat enamel and dentine samples (< +/- 0.3 microm profile) from unerupted human third molars. Groups of five specimens were placed in acidic solutions adjusted with alkali over the available pH range; citric, phosphoric and hydrochloric acid were adjusted with sodium hydroxide and citric acid with trisodium citrate. Tissue loss was calculated by profilometry. Results showed that under these conditions citric acid caused far more erosion over the pH range employed than phosphoric acid for both tissue types. Citric acid compared with hydrochloric acid highlighted dissolution and chelation effects. Phosphoric acid caused minimal erosion over pH 3 for enamel and pH 4 for dentine. These factors could be considered in order to reduce the erosivity of acidic soft drinks.

The effect of pH on the erosion of dentine and enamel by dietary acids in vitro

The reported incidence of tooth erosion caused by acidic soft drinks has been increasingly documented. Citric and phosphoric acids are the two main dietary acids present in these soft drinks. Many variables need to be determined in order to assess risk factors for dental erosion caused by beverage consumption including pH, titratable acidity, pKa, buffering capacity, hence the aim of these in vitro investigations. Methodologies included profiling flat enamel and dentine samples (< +/- 0.3 microm profile) from unerupted human third molars. Groups of five specimens were placed in acidic solutions adjusted with alkali over the available pH range; citric, phosphoric and hydrochloric acid were adjusted with sodium hydroxide and citric acid with trisodium citrate. Tissue loss was calculated by profilometry. Results showed that under these conditions citric acid caused far more erosion over the pH range employed than phosphoric acid for both tissue types. Citric acid compared with hydrochloric acid highlighted dissolution and chelation effects. Phosphoric acid caused minimal erosion over pH 3 for enamel and pH 4 for dentine. These factors could be considered in order to reduce the erosivity of acidic soft drinks.

Effect of time on the remineralisation of enamel by synthetic saliva after citric acid erosion

The aim of this in vitro study was to determine the influence of remineralisation time on rehardening of surface-softened enamel after citric acid erosion. Seven groups of 13 samples of human enamel were eroded in 0.3% citric acid at pH 3.2 for 2 h followed by profilometric measurements. Individual groups of specimens were placed in artificial saliva for 1, 2, 4, 6, 9 or 24 h. A control group was placed in isotonic saline for 24 h. After new profilometric measurements samples were ultrasonicated stepwise up to 480 s with profilometric measurements performed at 5, 30, 120, 240 and 480 s to measure the depth of surface softening. The control group had a softened surface layer of mean thickness 2.9 microm. Mineral deposition was seen at all remineralisation times by scanning electron microscopy. Exposure to artificial saliva for 1, 2 or 4 h produced a partial rehardening of the softened enamel; the additional surface losses produced by ultrasonication were lower and time delayed compared to the control group. Specimens remineralised for 6, 9 and 24 h showed little evidence of surface loss after ultrasonication. The data suggest that a complete rehardening of the softened enamel in vitro is reached after a remineralisation time of 6 h. These data are of clinical relevance to tooth wear. However, there is a need for studies in situ of enamel demineralisation and remineralisation.

Membrane fluidity effects of estratrienes

Estrogens have demonstrable neuroprotective effects. This fact has lead to the proposed use of estrogens for the prevention and/or treatment of Alzheimer's disease. The exact protective mechanism estrogens provide is not fully understood. In this report, a potential non-genomic mechanism for estratrienes involving alterations in membrane fluidity was studied. Steroids, such as estrogen, are known to be membrane-active and can alter the lipid packing. In this study we used fluorescent methodologies to address the effect of naturally occurring steroids (17alpha and 17beta-estradiol, testosterone, and progesterone) and new estratriene analogs on membrane fluidity using liposomes and HT-22 hippocampal cells. The study's results indicate steroids, based on the estratriene nucleus, can modulate lipid packing as evidenced by (1) decreased membrane fusion events and (2) decreased membrane fluidity. The effects on the membrane were both time and concentration dependent. It was also demonstrated through rational design estratriene analogs can be synthesized with enhanced membrane effects. Finally, in a glutamate-induced toxicity HT-22 model, we also demonstrated cellular protection with the estratriene-based molecules and analogs. The data suggest the plethora of cellular actions of estrogens may relate to or be influenced by membrane effects of the steroid.

Transgene delivery with a cationic lipid in the presence of amyloid beta (betaAP) peptide

The ability of a cationic lipid to deliver plasmid DNA (pDNA) in presence of the neurotoxic fragment of amyloid beta-peptide was evaluated. Pre-treatment of cells with betaAP (25-35) peptide resulted in a modest increase in transgene expression. When betaAP (25-35) peptide was mixed with the pDNA/liposome complex and used, the complexes lost their ability to transfect. However, the reverse sequenced betaAP (35-25) peptide demonstrated no significant differences in transgene expression in pre-treated cells, and in cells where betaAP (35-25) peptide was mixed with pDNA/liposome complexes and transfected. The amount of pDNA delivered to the cells was decreased in presence of betaAP (25-35) as measured with flow cytometry using fluorescently labeled liposomes. The decreased endocytosis may be due to their rod-like structure formation as demonstrated by electron microscopy and atomic force microscopy (AFM). These results demonstrate that betaAP (25-35) peptide may interfere with gene delivery with cationic systems.

In situ gel formulations for gene delivery: release and myotoxicity studies

The in vitro release of plasmid DNA and salmon sperm DNA from in situ gel formulations was investigated. Two in situ gel systems were studied: (a) an interpolymeric complex (IPC) of water-soluble polymers polymethacrylic acid (PMA) and polyethylene glycol (PEG) and (b) a hydroxypropylmethylcellulose-carbopol system (H:C). Two-way analysis of variance with replication demonstrated that both gel composition and medium pH influenced significantly the release of plasmid DNA from in situ gel formulations. When the release of both types of DNA was compared, higher release was observed for plasmid DNA compared to genomic salmon sperm DNA. Conformational analysis of the released plasmid DNA showed that DNA was released without degradation, but with remarkable conversion from supercoiled (SC) to open circular (OC). In addition, the tested in situ gel systems demonstrated protection from DNAse I degradation. The myotoxicity of the injectable gelling solutions was assessed by the cumulative release of creatine kinase (CK) over 120 min from the isolated rodent extensor digitorum longus (EDL) muscle. A higher level of cumulative CK was observed for IPC when compared to H:C (2:1). These results demonstrate that the in situ gelling systems can be considered as a valuable injectable controlled-delivery system for pDNA in their role to provide protection from DNAse degradation.

Pharmacokinetics of plasmid DNA in the rat

PURPOSE

The pharmacokinetics of plasmid DNA after IV bolus administration in the rat by following supercoiled (SC), open circular (OC), and linear (L) pDNA forms of the plasmid.

METHODS

SC, OC, and L pDNA were injected at 2,500, 500, 333, and 250 microg doses. The concentrations in the bloodstream of OC and L pDNA were monitored.

RESULTS

SC pDNA was detectable in the bloodstream only after a 2,500 microg dose, and had a clearance of 390(+/-50) ml/min and Vd of 81(+/-8) ml. The pharmacokinetics of OC pDNA exhibited non-linear characteristics with clearance ranging from 8.3(+/-0.8) to 1.3(+/-0.2) ml/min and a Vd of 39(+/-19) ml. L pDNA was cleared at 7.6(+/-2.3) ml/min and had a Vd of 37(+/-17) ml. AUC analysis revealed that 60(+/-10) % of the SC was converted to the OC form, and nearly complete conversion of the OC pDNA to L pDNA. Clearance of SC pDNA was decreased after liposome complexation to 87(+/-30) ml/min. However the clearance of OC and L pDNA was increased relative to naked pDNA at an equivalent dose to 37(+/-9) ml/min and 95(+/-37) ml/min respectively.

CONCLUSIONS

SC pDNA is rapidly metabolized and cleared from the circulation. OC pDNA displays non-linear pharmacokinetics. Linear pDNA exhibits first order kinetics. Liposome complexation protects the SC topoform, but the complexes are more rapidly cleared than the naked pDNA.

Erosion of dentine and enamel in vitro by dietary acids: the effect of temperature, acid character, concentration and exposure time

Sales of soft drinks has been increasing by 56% over the last 10 years and are estimated to keep rising at about 2-3% a year. Further, the reported incidence of tooth erosion has been increasingly documented. Whilst these factors could well be linked, many individuals with erosive diets are not presenting with erosion. This would suggest the effects of many variables, hence the aim of these investigations. Methodologies included preparing enamel and dentine samples from unerupted human third molars. Groups of five specimens were placed in citric acid over a temperature range of 5-60 degrees C for 10-min exposures; placed in citric, lactic, malic or phosphoric acid (0.05, 0.1, 0.5, and 1% (w/v)) for 10-min exposures; and placed in the same three organic hydroxy acids at 0.3% (w/v) or phosphoric acid at 0.1% (w/v) for 3 x 10-min exposures. Tissue loss was determined by profilometry. Results showed that increasing temperature, concentration and exposure time increased the erosion of dentine and enamel. This study has shown that under highly controlled conditions, erosion of dentine and enamel by dietary acids can be greatly influenced in vitro by temperature, concentration, type of acid and exposure time. These factors could be employed in order to reduce the erosivity of soft acidic drinks.

Biodegradable pH-sensitive surfactants (BPS) in liposome-mediated nucleic acid cellular uptake and distribution

The impact of biodegradable pH-sensitive surfactant (BPS)-liposomes on nucleic acid, i.e., oligonucleotide and plasmid DNA, cellular delivery was examined. Fluorescein-labeled nucleic acids complexed with 1,2-dioleoyl-3-trimethylammonium propane cationic liposomes and BPS at a charge ratio (+/-) of 10 were incubated in CV-1 cells and analyzed by flow cytometry. The fluorescence intensity of oligonucleotides but not plasmid DNA complexed with BPS-liposomes was higher than those complexed with BPS-free liposomes at early time points. However, when cells were fixed to equalize the intracellular pH since fluorescein, a pH-sensitive fluorophore, has higher fluorescence intensity in alkaline pH than acidic, no difference in intensity was observed. This indicated the incorporation of BPS in liposomes did not increase oligonucleotide cellular uptake over control liposomes, but redistributed oligonucleotides into a more basic environment, e.g., cytoplasm. An explanation consistent with the presented data is the formation of small transient membrane defects within the endosomal membrane as presented previously [Liang, E., Hughes, J.A., 1998a. Membrane fusion and rupture in liposomes: effect of biodegradable pH-sensitive surfactants. J. Membr. Biol. 166, 37-49.]. The above findings suggested that BPS may be effective agents of disrupting one of the major barriers, endosomal membrane, to enhance nucleic acid cellular transport.

Adeno-associated virus mediated gene transfer into primary rat brain neuronal and glial cultures: enhancement with the pH-sensitive surfactant dodecyl 2-(1'-imidazolyl) propionate

This study evaluated the effects of a novel, pH-sensitive surfactant, dodecyl 2-(1'-imidazolyl) propionate (DIP), on cationic lipid mediated transfection in primary rat brain neuronal and glial cultures. The cationic lipid complex DOTAP/DOPE (1, 2-dioleoyl-3-trimethylammonium propionate and dioleoyl phosphatidylethanolamine, respectively) was added over a range of concentrations (0-120 microg/ml) with DNA concentration kept constant (1.6 microg/ml). The neuron-specific enolase (NSE) and cytomegalovirus (CMV) promoters were found to drive green fluorescent protein (GFP) expression in neuron-enriched and glial cultures, respectively, using adeno-associated virus (AAV) derived constructs. NSE-driven GFP expression was not observed in glial cultures. Addition of DOTAP/DOPE increased transfection efficiency over a wide range of lipid concentrations (5-50 microg/ml) keeping DNA concentration constant (1.6 microg/ml). Addition of DIP to the lipid/DNA complex increased maximum transfection efficiencies in glial and neuronal cultures 2-3-fold. Transfection efficiencies were at their maximum with a similar total lipid concentration (50 microg/ml) in both cell-types in the presence of DIP. Neuronal cultures were more sensitive than glia to the toxic actions of DOTAP/DOPE, with or without DIP. These results indicate that AAV-mediated gene-transfer to neurons and glia can be facilitated by addition of a pH-sensitive surfactant to cationic liposome/DNA complexes and that endosomal escape could be a limiting factor in transgene expression.

Modulation of ras p21 oncoprotein levels and DNA strand breakage in human cells with chemotherapeutic agents and/or deferoxamine

Oncogenes are involved with the regulation of cellular proliferation. Ras oncogenes can be activated by chemical treatment and any increased activity could be modulated by further chemical treatment. In the present study, therefore, ras p21 protein expression was examined in in vitro cultures of human lymphocytes treated with mitomycin C and in the human colon adenocarcinoma Caco-2 cell line treated with doxorubicin with and without deferoxamine. Both chemotherapeutic agents act partially through oxygen radical mechanisms. Increases in p21 protein levels were seen with mitomycin C but no clear response was seen with doxorubicin. However, deferoxamine, with and without doxorubicin, altered p21 expression. Deferoxamine is an iron chelator so these results support the hypothesis that oxygen radicals were responsible for the altered p21 protein levels. Modulating responses were confirmed by measuring DNA strand-breakage in the Comet assay after treatment with doxorubicin and deferoxamine. Alterations of ras p21 protein expression in vitro might prove a suitable system for examining modulating effects on chemical carcinogens.

Relative susceptibility of deciduous and permanent dental hard tissues to erosion by a low pH fruit drink in vitro

OBJECTIVES

The objectives of this study were two-fold: (1) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following 15days' exposure to a single low pH orange drink; and (2) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following exposure to the product 2 versus 4 times per day for 15days.

METHODS

This in vitro study employed the validated methodology described by West and co-workers [Journal of Dentistry, 1998;26:329-335.]

RESULTS

In all four tissues, erosion was progressive over time, though this pattern was more linear in enamel than in dentine. In general, erosion of enamel was greater in the deciduous tissue, while erosion of dentine was greater in the permanent tissue. However, these differences were rarely of statistical significance. Increasing frequency of exposure resulted in a non-proportional increase in tissue loss.

CONCLUSIONS

Differences in susceptibility of deciduous and permanent tissues to erosion by a low pH drink in vitro appear to exist, though these may not be of statistical significance. Care may be indicated in the delivery of dietary advice, since reduced frequency of exposure to a low pH drink does not appear to result in a proportional reduction in tissue loss.

Erosion of deciduous and permanent dental hard tissue in the oral environment

OBJECTIVES

The objectives of this study were two-fold: (1) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following consumption of a single low pH orange drink for 15days; and (2) to determine (by surfometry) loss of deciduous and permanent enamel and dentine following consumption of the product 2 versus 4 times per day for 15days.

METHODS

Sixteen healthy volunteers participated in a single centre, single blind, 2-phase crossover study, conducted according to Good Clinical Practice, and employing the validated model described by West and co-workers (Journal of Dentistry 1998; 26:329-335).

RESULTS

In all tissues, erosion was progressive over time, the pattern being more linear in enamel than in dentine. In general, erosion of deciduous enamel was greater than that of permanent enamel, though this difference was significant only for those specimens exposed to 4 drinks per day. Conversely, erosion of dentine was generally greater in the permanent tissue, though differences rarely reached conventional levels of statistical significance. Increasing frequency of consumption resulted in increased loss of tissue, but this difference was neither proportional nor consistently statistically significant.

CONCLUSIONS

It is concluded that statistically significant differences in susceptibility of deciduous and permanent enamel to erosion appear to emerge over time and with increasing frequency of consumption. This is of importance clinically given the reduced dimensions of the deciduous dentition and the element of 'abuse' of soft drinks by the child population. Further development of soft drinks with low erosive potential is recommended.

Pre-exposure of cells to cationic lipids enhances transgene delivery and expression in a tissue culture cell line

Several factors influence non-viral transfection in tissue culture models including nature of the cationic lipid, plasmid construction, and DNA lipid complex, among others. The cell line itself is another confounding variable. Each subcellular population may respond independently to the transgene or specific delivery vector with regards to toxicity or transgene expression. In this study, the SKnSH (human neuroblastoma) and COS-1 (African green kidney) cells were exposed to three different treatments A, B, and C. Treatment A refers to cells obtained from American Type Culture Collection (ATCC) and cultivated as recommended, treatment B to cells that were grown in presence of cationic lipids for two weeks, and treatment C to cells that were grown in presence of cationic lipids for two weeks followed by normal media for two weeks to determine if lipid mediated effects were reversible. Treatment B resulted in a three-fold increase in transgene expression of a reporter gene as compared to the other treatments. This increase in transgene expression appeared not to be related to alterations in toxicity. Interestingly, the fluid phase endocytic uptake of fluorescently labeled oligonucleotides was increased in treatment B. However, there was no significant difference in the cellular-associated signal when fluorescently labeled plasmid-DNA was evaluated. In COS-1 cells, no difference in transfection was observed with treatment B illustrating that cell lines respond independently. In conclusion, pre-exposure of SKnSH cells to cationic liposomes (treatment B) resulted in higher transgene production.

The effect of lyophilization on plasmid DNA activity

The effect of lyophilization of plasmid DNA's ability to express an encoded protein was studied. Plasmid DNA, pRL-CMV expressing Renilla luciferase, was purified and stored in Tris-ethylenedi-aminetetraacetic acid (EDTA) buffer. Aliquots of the plasmid were lyophilized using analytical equipment, both alone and in the presence of carbohydrate. Samples were rehydrated and subject to functional and structural analyses. Analytical techniques included transfection efficiency in COS-1 cells, agarose gel electrophoresis, dimethylethylenediamine (DMED) assay for abasic sites, circular dichroism measurement, and UV spectroscopy. The lyophilization of pRL-CMV plasmid DNA resulted in a statistically significant loss of transfection efficiency (p < 0.05). Mono- and disaccharides could completely restore transfection efficiency. Agarose gel electrophoresis and the DMED assay demonstrated no change in gross plasmid structure or increase in abasic sites during lyophilization, respectively. Changes in DNA form, as measured by a change in ellipsisity, were observed on lyophilization. However, these changes were transient and were not shown to be responsible for loss of transfection efficiency. A hyperchromic effect was observed at 260 nm after lyophilization and could be reversed by the presence of carbohydrates. Lyophilization causes a decrease in plasmid DNA activity as measured by an in vitro transfection assay. Carbohydrates can ameliorate this decreased activity, which may be due to structural changes seen during the lyophilization process.

Effects of pH and concentration of citric, malic and lactic acids on enamel, in vitro

OBJECTIVE

Dental erosion associated with soft drink consumption probably results from the contained dietary acids in the formulations. The pH value of any formulation is an important variable in acid erosion but not necessarily the only important factor. The aim of this study was to measure enamel erosion by citric, malic and lactic acids at pH values and acid concentrations representative of a range found in soft drink formulations and to determine the effect of adding calcium to citric acid.

METHODS

Flat ground enamel samples were prepared from unerupted human third molar teeth. Groups of five specimens were placed in citric, malic and lactic acid solutions of different pH and acid concentration for three by 10 min exposures at 35 degrees C. Enamel loss was measured by profilometry. Enamel specimens were also exposed to citric acid solutions containing calcium at different pH values and at the same pH with different concentrations of calcium.

RESULTS

Numerical data and contour plots for each acid showed a similar pattern for increasing erosion with decreasing pH and increasing acid concentration and vice versa for decreasing erosion. Increasing the concentration of calcium in a fixed pH citric acid solution resulted in decreased erosion. This effect was most marked at higher pH.

CONCLUSIONS

This study has shown that under highly controlled conditions the erosion of enamel by solutions of dietary acids is influenced by the interplay of pH, acid concentration and presence of calcium. These variables and in particular the concentration of calcium could be manipulated to produce soft drinks with reduced erosivity to enamel.

Infection of the macrophage cell line NR8383 with Mycobacterium tuberculosis (H37Ra) leads to an increase in oligodeoxynucleotide accumulation

Mycobacterium tuberculosis infection continues to be a daunting clinical challenge. Although it may well be one of the most studied bacteria in history, several aspects of its pathology remain a mystery. The resurgence of drug-resistant M. tuberculosis strains and with its unusual pathology have promoted a renewed basic and clinical research interest in developing new therapies to combat this pathogen. The primary localization site for M. tuberculosis is within alveolar macrophages. Drug delivery strategies and novel therapeutic agents designed to target alveolar macrophages may lead to efficient destruction of M. tuberculosis. Oligodeoxynucleotides (ODN) are short segments of nucleic acids that can interfere with transcription and translation processes. In this report, a monocyte-macrophage cell line was characterized in regard to ODN transport in the presence or absence of M. tuberculosis infection. The cells accumulated ODN in a time-dependent and concentration-dependent manner, regardless of the presence of serum. After 4 hours of incubation with M. tuberculosis (multiplicity of infection [MOI] 10:1), infected NR8383 cells demonstrated 1.5-7-fold increase in fluorescein isothiocyanate (FITC)-labeled phosphorothioate ODN accumulation as measured by flow cytometry. The increase in uptake was associated only with fluorescent-labeled ODN and not labeled markers of fluid phase endocytosis (e.g., tetramethylrhodamine isothiocyanate [TRITC], FITC-labeled dextran). NR8383 cells activated by phytohemagglutinin (PHA) did not demonstrate a significant increase in the uptake of either FITC-labeled dextran or FITC-labeled ODN. These studies demonstrate that NR8383 cells that have been infected with M. tuberculosis can specifically accumulate ODN, and this route of accumulation may lead to a means of drug targeting to mycobacteria-containing cells.

Quantifiable analysis of human immunoglobulin heavy chain class-switch recombination to all isotypes

Somatic recombinational events, including the immunoglobulin heavy chain class-switch, are a normal feature of B-cell maturation. To enable comprehensive and sensitive class-switch analysis in ex vivo human B cells, we have developed multiple digestion-circularization PCR (DC-PCR) techniques for quantifiable detection of switching to all immunoglobulin isotypes. This technology was validated by extensive sequencing of PCR products, tests with control non-lymphoid cells and B-cell lines of known isotypic specificities, and by demonstrating DC-PCR selectivity in a model system. With tonsillar B-cell DNA, switching to gamma 3, gamma 1, alpha1, gamma 2, gamma 4 and alpha2 isotypes was reproducibly detectable among different individuals. Levels of epsilon switching were relatively low and usually required higher total amounts of template DNAs for detection. Quantitation of alpha1 class switching in a panel of human tonsillar whole B cells was performed by the internal-competitor approach, and showed a pattern consistent with previous studies on IgA+ tonsillar cells. We demonstrate that these assays can rapidly show germline status or specific switch rearrangements in B lymphoid cell lines.

Enhanced transgene expression in rat brain cell cultures with a disulfide-containing cationic lipid

The transfection efficiency of a disulfide-containing cationic lipid, 1',2' dioleoyl-sn-glycero-3'-succinyl-2-hydroxyethyl disulfide ornithine conjugate (DOGSDSO) and its non-disulfide analog (DOGSHDO) were compared in neuronal, astroglial and microglial cultures from newborn rat cerebral cortex. We hypothesized that the relatively high intracellular concentrations of reductive substances in the cytoplasm may help to cleave the reversible disulfide bond in DOGSDSO, thus increasing free DNA and decreasing toxicity due to rapid degradation of the lipid. We have demonstrated through mass spectrometric analysis that a reductive compound, e.g. dithiothreitol (DTT) could degrade the disulfide lipid. DOGSDSO was more efficient at transfecting each type of brain cell than were the non-disulfide DOGSHDO and DOTAP (1,2-dioleoyl-3-trimethyl-ammonium-propane) liposomes. These results demonstrate that disulfide-containing cationic liposomes facilitate gene transfection in cultured rat brain cells.

Cytogenetic damage and ras p21 oncoprotein levels from patients with chronic obstructive pulmonary disease (COPD), untreated lung cancer and healthy controls

The purpose of the present communication was to determine in patients with chronic obstructive pulmonary disease (COPD), untreated lung cancer and healthy controls if there was a possible association between the disease state and biomarkers of cytogenetic damage and ras p21 oncoprotein levels, and if various exogenous confounding factors such as smoking habit and endogenous ones (sex, cancer in the immediate family) could affect these biomarkers. The individuals in all groups were as well-matched as possible for age to determine if this could be eliminated as a confounder. Peripheral blood and plasma were collected from 20 COPD patients, 31 cancer patients and 20 healthy controls. Chromosomal aberrations (CA), sister chromatid exchanges (SCE) and high frequency SCE cells (HFC) were examined from the blood and ras p21 oncoproteins from the plasma. These parameters were used as biomarkers of genotoxic anomalies. All the biomarkers were examined for their relationship to the confounding factors. Results were analysed by a t-test, analysis of variance (ANOVA) and stepwise multivariate regression analysis. There was an increase in CA, although not statistically so, in COPD and cancer patients by comparison with healthy controls, but there was a statistically significant increase in SCE, HFC and ras p21 oncoproteins. There was also a statistically significant difference between respiratory volume parameters in COPD patients and controls. Respiratory parameters were not measured in cancer patients. Ras p21 oncoproteins were also statistically significantly increased in the COPD and cancer patients, suggesting that the disease state alone might be sufficient to increase the oncoproteins, or that some of the COPD patients were in the process of developing cancer or perhaps some would die from COPD before cancer developed. Smoking was shown to have a marked effect on all parameters investigated. Ex-smokers showed less effects. Since age was very well controlled, there was little effect due to age. There was an effect due to sex, but cancer in the immediate family had little effect on any of the parameters.

Synthesis of a single-tailed cationic lipid and investigation of its transfection

Single-tailed cationic lipids were originally reported to have low transfection efficiency and high toxicity in plasmid delivery. We hypothesized that particular single-tailed cationic lipids may also function in plasmid transfection. To test this hypothesis, we synthesized a new cationic lipid-oleoyl ornithinate (OLON). To decrease cytotoxicity, we then introduced a potential biodegradable ester bond in the tail of lipid yielding 6-lauroxyhexyl ornithinate (LHON). The data demonstrated that the cytotoxicity of LHON was lower than that of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or OLON. To investigate the transfection activity of the new lipids and determine the cellular uptake of DNA/liposome complexes, we compared the transfection of liposomes produced from double-tailed 1',2'-dioleyl-sn-glycero-3'-succinyl-1, 6-hexanediol ornithine conjugate (DOGSHDO) with an ornithine headgroup, single-tailed OLON with an ornithine head group, double-tailed DOTAP with quaternary amine group, and single-tailed cetyltrimethylammonium bromide (CTAB) with a quaternary amine group. At the optimal ratios as defined in transfection experiments, OLON/DOPE had more than 10 times the transgene expression than other liposomes even though the DNA uptake was not necessarily greater. In the experiments comparing the release of DNA from DNA/liposome complexes by anionic substances, a greater fraction of DNA was released from DNA/OLON/DOPE complexes than that from DNA/DOTAP/DOPE complexes.

Factors that impact nurses' use of electronic mail (e-mail)

As electronic applications are used increasingly in healthcare, nurses are being challenged to adopt them. Electronic mail (e-mail) is an electronic tool with general as well as healthcare uses. E-mail use may be an opportunity to learn a tool that requires skills similar to those used in other applications. This study aimed to identify barriers and facilitators that impact nurses' use of e-mail in the workplace. Data for this study were gathered using focus group methodology. Content analysis identified and labeled factors into seven major categories. Specific factors identified were generally consistent with those previously described in the literature as affecting use of computers in general. However, there were several additional factors identified that were not reported in other previous studies: lack of face-to-face communication, individual writing skills, recency of any educational experience, volume of mail received, password integrity, and technical support. Findings from this study provide information for any individual involved in introducing or updating an e-mail system in a healthcare environment.

A biofunctional assay to study pRL-CMV plasmid DNA formulation stability

The ability of a plasmid DNA formulation to code for a functional protein was assayed as a marker for plasmid DNA stability using a cotransfection method to measure transcription efficiency. This method shows increased sensitivity and reproducibility over single plasmid transfection methods. Method validation, by measuring DNA degradation rates, demonstrates that buffer choice may be of some importance in the pharmaceutical formulation of plasmid DNA. Degradation rates dependant on citrate buffer concentration were observed. This cotransfection method has proven superior to standard agarose gel electrophoresis in quantifying subtle pRL-CMV plasmid DNA damage and could be used to help predict stability of a final plasmid DNA dosage form.

Examination of ras oncoproteins in human plasma from healthy controls and workers exposed to petroleum emissions, including benzene-related compounds

Ras oncoproteins in blood plasma from workers exposed to petroleum emissions and unexposed controls were examined from Polish and Estonian samples. Twenty-four workers and 35 unexposed controls were examined from Poland and 97 exposed and 40 unexposed controls from Estonia. Of the Estonian workers, 50 were exposed to benzene in a benzene production plant and 47 to polyaromatic hydrocarbons and benzene in a cokery. Blood plasma proteins were separated by gel electrophoresis, transferred to a nitrocellulose membrane by Western blotting and detected by chemiluminescence using a monoclonal antibody as the primary antibody. There were no statistically significant differences between the exposed and the control groups in either the Polish or the Estonian samples.

Use of dithiodiglycolic acid as a tether for cationic lipids decreases the cytotoxicity and increases transgene expression of plasmid DNA in vitro

Two major barriers that limit cationic lipids in gene delivery are low transfection efficiency and toxicity. In the present studies, we used dithiodiglycolic acid as a new tether for the polar and hydrophobic domains of a cationic lipid, cholesteryl hemidithiodiglycolyl tris(aminoethyl)amine (CHDTAEA). We compared the transfection activity and toxicity of CHDTAEA with its nondisulfide analogue and cholesteryl N-(dimethylaminoethyl) carbamate (DC-Chol). The liposomes of CHDTAEA had more than 2 orders of magnitude greater transfection activity than DC-Chol in CHO cells and 7 times greater transfection activity in SKnSH cells. CHDTAEA also demonstrated much less toxicity than the other two lipids. Dithiodiglycolic acid may act as an excellent linker in the application of cationic lipid syntheses.

Building a balanced scorecard for a burn center

The Balanced Scorecard provides a model that can be adapted to the management of any burn center, burn service or burn program. This model enables an organization to translate its mission and vision into specific strategic objectives across the four perspective: (1) the financial perspective; (2) the customer service perspective; (3) the internal business perspective; and (4) the growth and learning perspective. Once the appropriate objectives are identified, the Balanced Scorecard guides the organization to develop reasonable performance measures and establishes targets, initiatives and alternatives to meet programmatic goals and pursue longer-term visionary improvements. We used the burn center at the University of Colorado Health Sciences Center to test whether the Balanced Scorecard methodology was appropriate for the core business plan of a healthcare strategic business unit (i.e. a burn center).

Oligonucleotide delivery: a cellular prospective

The use of oligonucleotides (ONs) for gene therapy of certain diseases has been discussed since the late 1970s. ONs are single stranded chains of nucleic acids that can hybridize with target nucleic acid sequences to inhibit specific proteins, and therefore allow selective treatment of various diseases. The use of ONs is limited due to their instability in biological tissues and difficulty in delivery to the intracellular compartments of the cell. Chemical analog approaches have been used to address the instability issue and delivery systems have been developed to increase cellular uptake of ONs. It is generally thought that ONs with or without a delivery system are transported into cells by endocytosis, and then accumulate within endosomes where they are significantly inactivated. The rate and extent of movement of ON from endosomes appears to be important in determining ON effects. Consequently, developing accessory compounds or delivery methods that enhance endosome to cytoplasm transfer may be vital to ON therapy. This review focuses on investigating mechanisms of various delivery approaches at the cellular/intracellular level that have demonstrated utility in increasing ON activity or cellular accumulation. The future prospects of ON delivery are also addressed.