An in vitro toxicological assessment of two electronic cigarettes: E-liquid to aerosolisation.

Interest in the toxicological assessment of iterations of e-cigarette devices, e-liquid formulations and flavour use is increasing. Here, we describe a multiple test matrix and in vitro approach to assess the biological impact of differing e-cigarette activation mechanism (button vs. puff-activated) and heating technology (cotton vs. ceramic wick). The e-liquids selected for each device contained the same nicotine concentration and flavourings. We tested both e-liquid and aqueous extract of e-liquid aerosol using a high throughput cytotoxicity and genotoxicity screen. We also conducted whole aerosol assessment both in a reconstituted human airway lung tissue (MucilAir) with associated endpoint assessment (cytotoxicity, TEER, cilia beat frequency and active area) and an Ames whole aerosol assay with up to 900 consecutive undiluted puffs. Following this testing it is shown that the biological impact of these devices is similar, taking into consideration the limitations and capturing efficiencies of the different testing matrices. We have contextualised these responses against previous published reference cigarette data to establish the comparative reduction in response consistent with reduced risk potential of the e-cigarette products tested in this study as compared to conventional cigarettes.

A contextualised e-cigarette testing strategy shows flavourings do not impact lung toxicity in vitro.

Vaping has the potential to reduce the individual health risks associated with smoking and e-cigarette flavours have been reported to help smokers' transition from cigarettes. In this manuscript, we provide evidence to support the reduced risk potential of e-cigarette aerosols and flavours by assessing commercially available e-liquids (Vuse ePod - Manufactured by British American Tobacco) in a 2D in vitro screening approach. We also analysed selected flavours using a more physiologically relevant 3D (MucilAir) whole aerosol exposure model, measuring toxicity and functional endpoints such as Trans Epithelial Electrical Resistance, Cilia Beat Frequency and Active Area. To contextualise responses, we have compared e-cigarette aerosol to cigarette smoke (1R6F research cigarette) and calculated the percentage reduction using a point of departure approach. We show that aerosolised flavoured e-liquids, (appropriately stewarded) do not increase the overall measured aerosol toxicity when compared to cigarette smoke. In fact, we demonstrate that the measured in vitro cellular toxicity of flavoured e-cigarette products remains > 95% reduced when compared to cigarette smoke toxicity, using point of departure (IC80) approach. These data indicate that the overall product toxicity is not increased in a flavour dependent manner and that flavoured e-cigarette products can potentially play a role in tobacco harm reduction.

A 3D in vitro comparison of two undiluted e-cigarette aerosol generating systems.

In vitro studies play an important role in supporting the toxicological assessment of e-cigarettes, with many current methods reliant on sophisticated in vitro exposure systems designed for conventional cigarette testing. In this study, we have compared two distinct systems; the modified Vitrocell VC10 and Borgwaldt LM4E designed to deliver undiluted e-cigarette aerosol. We assessed the cytotoxicity response of 3D reconstituted lung tissue (MucilAir) exposed to undiluted aerosol from ePen3 (closed modular e-cigarette) using these two exposure systems. As the induced cytotoxicity profiles were comparable, we then compared these responses against historical eBox (open modular e-cigarette) and 3R4F reference cigarette data to show evolution of product technology. This latter approach was deemed possible by monitoring intrinsic donor-to-donor control variability over a three-year period, bridging between exposure systems and observed biological responses. Despite the differences in the technology, on a puff-by-puff basis these machines gave remarkably similar cytotoxicity profiles for ePen3, as determined by MTT, and consistency of pre-cytotoxicity markers: transepithelial electrical resistance (TEER), cilia beat frequency and cilia active area. When responses are compared as a function of exposed nicotine concentration, we see differences due to the dynamics of the exposure systems. The parity of responses between the systems in generated undiluted aerosol has allowed us to compare back to previously published eBox data, irrespective of aerosol generating system and MucilAir donor, showing how evolution from open systems to podmod e-cigarette design can make a step change in the cytotoxicity profile of the product.

A screening approach for the evaluation of tobacco-free 'modern oral' nicotine products using Real Time Cell Analysis.

In many regulated industries there is an increasing pressure to provide timely and robust risk assessment data to support product launches. Real-time cell analysis (RTCA) is a tool that allows for the fast and relatively labour-free cytotoxic assessment of test compounds, compared to traditional methods. Here, we propose an application for the RTCA platform to provide a screening approach, to evaluate the cytotoxic potential of tobacco-free nicotine pouches, also termed modern oral product (MOP), to determine the contribution of differing nicotine strengths (4-11 mg) and a range of available flavour types from multiple markets, on overall product toxicity. Aqueous extracts were prepared for all products using 1 pouch in 20 mL cell culture media and applied to the cell system for 24 h. Test extract nicotine concentrations reflected the increases in product nicotine strength; however, these changes were not present in the same magnitude in the cytotoxicity data obtained from both primary human gingival fibroblasts (HGF) and an NCI-H292 human bronchial epithelial continuous cell line. Furthermore, across the range of flavours and product nicotine strengths tested, H292 cells whilst not the target organ for oral product use, accurately predicted the results seen in HGFs and could be considered a useful surrogate for fast screening studies. H292 cells are more easily cultured and for longer periods, offering a more compatible test system. In conclusion, the data demonstrate the utility of the RTCA platform for the quick assessment of a large range of product variants. Furthermore, for a cytotoxicity measure with this test product, the simple H292 cell line can predict outcomes in the more complex HGF and provide useful pre-clinical cytotoxicity screening data to inform the risk assessment of MOPs and the relative contribution of flavourings, nicotine and other components.

Adipose-only sentinel lymph nodes: a finding during the adaptation of a sentinel lymph node mapping algorithm with indocyanine green in women with endometrial cancer.

OBJECTIVE: To identify factors that affect successful adaptation of sentinel lymph node mapping and those that lead to unintended adipose-only sentinel lymph node identification. METHODS: Surgical and pathological data were prospectively collected on patients with endometrial cancer who underwent sentinel lymph node mapping with indocyanine green with or without pelvic and/or para-aortic lymph node dissection between November 2013 and April 2017. All mapping cases were performed with the robotic system. Adipose-only specimens were defined as a sentinel lymph node without a pathologically identified lymph node after ultrastaging. RESULTS: A total of 202 patients were included: 83% had endometrioid pathology, 12% serous, 3% carcinosarcoma, and 2% clear cell, with mixed pathology noted in 2%. The bilateral sentinel lymph node detection rate was 66%, and the rate of mapping at least a unilateral sentinel lymph node was 86%. Neither the bilateral nor the unilateral sentinel lymph node mapping rate changed with increased surgeon experience. The rate of adipose-only sentinel lymph node identification was more frequent when comparing the first 10 cases (37%), cases 11 - 30 (28%), and > 30 cases (9%) (P = 0.006). Body mass index > 30 kg/m2, uterine fibroids, The International Federation of Gynecology and Obstetrics (FIGO) grade, and histology were not found to have a statistically significant impact on either sentinel lymph node identification or adipose-only sentinel lymph node identification. Adipose-only sentinel lymph nodes were more likely with increased time from cervical injection to identification of the sentinel lymph node in the right hemipelvis. The median range was 28 min (14-73) for true sentinel lymph node identification vs 33 min (23-74) for adipose-only sentinel lymph node identification (P = 0.02). CONCLUSION: Patient and surgeon factors did not impact the identification of sentinel lymph nodes over time. Adipose-only sentinel lymph nodes were more frequently identified in the initial cases and represent a potential complication to adapting sentinel lymph node biopsy without lymphadenectomy. The increase in adipose-only sentinel lymph node identification that was associated with time from cervical injection may represent delayed or disrupted uptake of indocyanine green.

An approach to testing undiluted e-cigarette aerosol in vitro using 3D reconstituted human airway epithelium.

The data presented here show that to provide an estimate of the relative cytotoxicity and therefore potency of e-cigarettes, undiluted aerosol techniques can be used. With the emergence of electronic nicotine delivery systems, fit-for-purpose in vitro screening methods are required. Reconstituted 3D human airway epithelium, was exposed to undiluted aerosols at the air-liquid interface, using a Vitrocell VC 10. TEER, cilia beat frequency and cytotoxic responses were assessed. Using two smoking regimes (ISO and HCI) a 3R4F reference cigarette, produced IC50s of 5.2 and 2.1 min, 1458 ng/mL and 1640 ng/mL nicotine respectively. Using an open tank e-cigarette device, a full cytotoxicity dose-response curve was obtained giving an IC50 of 30 min with corresponding nicotine of 10,957 ng/mL, 6-14 times less cytotoxic than cigarette smoke. A commonly used e-liquid flavourant cinnamaldehyde and known skin sensitizer was added to the standard e-liquid formulation and used as an aerosolised positive control, at 0.1, 0.025, 0.01 and 0%, demonstrating a full dose response. The delivery of undiluted aerosols in vitro has resulted in increased method sensitivity, throughput and quantitative e-cigarette comparisons. A positive control aerosol generated from a 'safe' e-liquid benchmark can inform risk assessments on supportable levels of flavour ingredients.

African born women living with HIV in the United States: unmet needs and opportunities for intervention.

Africa born (immigrant) women comprise a disproportionate number of Black women living with HIV in the United States. Though they are at risk for mental health disorders, including psychological distress and depression, little is known about their experience with these important predictors of quality of life, retention in care and adherence to antiretroviral therapy. In this qualitative study, we used constructivist grounded theory to explore the psychosocial and mental health challenges of African born women living with HIV in Boston and New York City. We conducted one-on-one semi-structured interviews with 45 women. Major themes contributing to psychological distress and depressive symptoms included (1) pre-immigration HIV-related stigma; (2) persistent HIV-related stigma post-immigration, (3) undocumented immigration status, (4) economic insecurity, and (5) intimate partner violence (IPV). Many participants described ongoing depressive symptoms or histories of depressive episodes. Yet, most had not been formally diagnosed or treated for depression. Prayer, consultation with faith leadership, and support groups were described most frequently as useful interventions. Future research should explore these thematic areas among a larger, more representative sample of African born women living with HIV to determine differences by country of origin across thematic areas. These data would be useful to inform development of innovative and culturally appropriate interventions.

Positive reinforcement targeting abstinence in substance misuse (PRAISe): Study protocol for a Cluster RCT & process evaluation of contingency management.

There are approximately 256,000 heroin and other opiate users in England of whom 155,000 are in treatment for heroin (or opiate) addiction. The majority of people in treatment receive opiate substitution treatment (OST) (methadone and buprenorphine). However, OST suffers from high attrition and persistent heroin use even whilst in treatment. Contingency management (CM) is a psychological intervention based on the principles of operant conditioning. It is delivered as an adjunct to existing evidence based treatments to amplify patient benefit and involves the systematic application of positive reinforcement (financial or material incentives) to promote behaviours consistent with treatment goals. With an international evidence base for CM, NICE recommended that CM be implemented in UK drug treatment settings alongside OST to target attendance and the reduction of illicit drug use. While there was a growing evidence base for CM, there had been no examination of its delivery in UK NHS addiction services. The PRAISe trial evaluates the feasibility, acceptability, clinical and cost effectiveness of CM in UK addiction services. It is a cluster randomised controlled effectiveness trial of CM (praise and financial incentives) targeted at either abstinence from opiates or attendance at treatment sessions versus no CM among individuals receiving OST. The trial includes an economic evaluation which explores the relative costs and cost effectiveness of the two CM intervention strategies compared to TAU and an embedded process evaluation to identify contextual factors and causal mechanisms associated with variations in outcome. This study will inform UK drug treatment policy and practice. Trial registration ISRCTN 01591254.

Surveillance survey of family history in children with neural tube defects.

OBJECTIVE Although there are known risk factors for the development of neural tube defects (NTDs), little is known regarding the role of family history. The authors' goal in this study is to describe the family history in their population of patients with NTDs. METHODS Surveys were completed for 254 patients who were accompanied by their biological mother during their annual visit to the multidisciplinary Spina Bifida Clinic at Children's of Alabama. An NTD has been diagnosed in all patients who are seen in this clinic (myelomeningocele, lipomeningocele, split cord malformation, and congenital dermal sinus tract). Each mother answered questions regarding known NTD risk factors and their pregnancy, as well as the family history of NTDs, other CNS disorders, and birth defects. RESULTS The overall prevalence of family history of NTDs in children with an NTD was 16.9% (n = 43), of which 3.1% (n = 8) were in first-degree relatives. In patients with myelomeningocele, 17.7% (n = 37) had a positive family history for NTDs, with 3.8% in first-degree relatives. Family history in the paternal lineage for all NTDs was 8.7% versus 10.6% in the maternal lineage. Twenty-two patients (8.7%) had a family history of other congenital CNS disorders. Fifteen (5.9%) had a family history of Down syndrome, 12 (4.7%) had a family history of cerebral palsy, and 13 (5.1%) patients had a family history of clubfoot. Fourteen (5.5%) had a family history of cardiac defect, and 13 (5.1%) had a family history of cleft lip or palate. CONCLUSIONS The family history of NTDs was 16.9% in children with NTD without a difference between maternal and paternal lineage. This high rate of positive family history suggests that genetics and epigenetics may play a larger role in the pathogenesis of NTD in the modern era of widespread folate supplementation.

Validity of a condition specific outcome measure for fragile X syndrome: the Aberrant Behaviour Checklist-utility index.

BACKGROUND: The purpose of this study was to assess the construct validity of the Aberrant Behaviour Checklist-utility index (ABC-UI) by examining the relationship between healthcare resource utilisation by patients with fragile X syndrome (FXS) as well as burden experienced by their caregivers. METHOD: In 2011, a total of 350 US caregivers of individuals with FXS completed a questionnaire that captured information on FXS-related burden as well as the ABC-Community. Using the ABC-UI, a condition-specific outcome measure derived from the ABC-Community, five utility index categories were created: very low (0.00-0.33); low (0.34-0.66); moderate (0.67-0.77); high (0.78-0.89); and very high (0.90-1.00). Multivariable regression models examined the association between the utility value and nine burden-related outcomes. RESULTS: Approximately 2% of individuals with FXS were in the very low utility index category, 31% low, 27% moderate, 38% high and 3% very high. The median utility value was 0.74. Women with FXS and adults 18 years and older had higher values. Regression results indicate that individuals with higher utility values were more likely to have fewer specialist visits, use fewer prescription medications, need fewer hours of unpaid caregiving, inflict fewer caregiver injuries and have caregivers with fewer mental health provider visits. CONCLUSIONS: The ABC-UI appears to function well as condition-specific outcome measure, and as an indicator of health-related quality-of-life and economic burden in individuals with FXS. Among patients with FXS in the US and their caregivers, significant differences in health care resource utilisation and burden exist across health state utility categories.

Aggression in fragile X syndrome.

BACKGROUND: Individuals with fragile X syndrome (FXS), especially men, have long been described as presenting with significant behavioural challenges. Despite this known aspect of the phenotype, there has been little research exploring the prevalence, frequency, nature or consequences of aggressive behaviour in FXS. METHODS: This study used survey methodology to gather caregiver reports on the types, frequency and severity of aggressive behaviour in 774 individuals with FXS. RESULTS: Based on caregiver report, nearly all (>90%) male and female individuals were reported to have engaged in some aggression over the previous 12 months, with a third of male cases and slightly fewer than 20% of female cases being described as engaging in moderate to severe aggression or being diagnosed or treated for aggression. Further, aggressive behaviours in male individuals were serious enough that 30% had caused injuries to caregivers and 22% had caused injuries to peers or friends. Sensory issues and hyperactivity were significant predictors of the frequency of aggressive acts, while sensory issues and anxiety were predictive of the severity of aggression. Traditional behaviour management techniques as well as medication was described as the most common and successful treatment options. CONCLUSIONS: Aggressive behaviours are a significant concern for a subsample of both male and female individuals with FXS. Given that sensory concerns were predictive of both the frequency and the severity of aggression suggests these behaviours may be a reactive means of escaping uncomfortable situations.

Detection of Foot-and-mouth Disease Virus RNA and Capsid Protein in Lymphoid Tissues of Convalescent Pigs Does Not Indicate Existence of a Carrier State.

A systematic study was performed to investigate the potential of pigs to establish and maintain persistent foot-and-mouth disease virus (FMDV) infection. Infectious virus could not be recovered from sera, oral, nasal or oropharyngeal fluids obtained after resolution of clinical infection with any of five FMDV strains within serotypes A, O and Asia-1. Furthermore, there was no isolation of live virus from tissue samples harvested at 28-100 days post-infection from convalescent pigs recovered from clinical or subclinical FMD. Despite lack of detection of infectious FMDV, there was a high prevalence of FMDV RNA detection in lymph nodes draining lesion sites harvested at 35 days post-infection, with the most frequent detection recorded in popliteal lymph nodes (positive detection in 88% of samples obtained from non-vaccinated pigs). Likewise, at 35 dpi, FMDV capsid antigen was localized within follicles of draining lymph nodes, but without concurrent detection of FMDV non-structural protein. There was a marked decline in the detection of FMDV RNA and antigen in tissue samples by 60 dpi, and no antigen or viral RNA could be detected in samples obtained at 100 dpi. The data presented herein provide the most extensive investigation of FMDV persistence in pigs. The overall conclusion is that domestic pigs are unlikely to be competent long-term carriers of infectious FMDV; however, transient persistence of FMDV protein and RNA in lymphoid tissues is common following clinical or subclinical infection.

Sleep-disordered breathing in patients with myelomeningocele.

OBJECT A paucity of literature examines sleep apnea in patients with myelomeningocele, Chiari malformation Type II (CM-II), and related hydrocephalus. Even less is known about the effect of hydrocephalus treatment or CM-II decompression on sleep hygiene. This study is an exploratory analysis of sleep-disordered breathing in patients with myelomeningocele and the effects of neurosurgical treatments, in particular CM-II decompression and hydrocephalus management, on sleep organization. METHODS The authors performed a retrospective review of all patients seen in their multidisciplinary spina bifida clinic (approximately 435 patients with myelomeningocele) to evaluate polysomnographs obtained between March 1999 and July 2013. They analyzed symptoms prompting evaluation, results, and recommended interventions by using descriptive statistics. They also conducted a subset analysis of 9 children who had undergone polysomnography both before and after neurosurgical intervention. RESULTS Fifty-two patients had polysomnographs available for review. Sleep apnea was diagnosed in 81% of these patients. The most common presenting symptom was "breathing difficulties" (18 cases [43%]). Mild sleep apnea was present in 26 cases (50%), moderate in 10 (19%), and severe in 6 (12%). Among the 42 patients with abnormal sleep architecture, 30 had predominantly obstructive apneas and 12 had predominantly central apneas. The most common pulmonology-recommended intervention was adjustment of peripheral oxygen supplementation (24 cases [57%]), followed by initiation of peripheral oxygen (10 cases [24%]). In a subset analysis of 9 patients who had sleep studies before and after neurosurgical intervention, there was a trend toward a decrease in the mean number of respiratory events (from 34.8 to 15.9, p = 0.098), obstructive events (from 14.7 to 13.9, p = 0.85), and central events (from 20.1 to 2.25, p = 0.15) and in the apnea-hypopnea index (from 5.05 to 2.03, p = 0.038, not significant when corrected for multiple measures). CONCLUSIONS A large proportion of patients with myelomeningocele who had undergone polysomnography showed evidence of disordered sleep on an initial study. Furthermore, 31% of patients had moderate or severe obstructive sleep apnea. Myelomeningocele patients with an abnormal sleep structure who had undergone nonoperative treatment with peripheral oxygen supplementation showed improvement in the apnea-hypopnea index. Results in this study suggested that polysomnography in patients with myelomeningocele may present an opportunity to detect and classify sleep apnea, identify low-risk interventions, and prevent future implications of sleep-disordered breathing.

Assessing health-related quality of life in children with spina bifida.

OBJECT: The purpose of this study is to explore various aspects of health-related quality of life (HRQOL) in children with spinal dysraphism. METHODS: The authors enrolled a prospective cohort of 159 patients from the multidisciplinary spina bifida clinic. Surveys were distributed to caregivers of patients with spina bifida who were 5 years old and older. Data were collected using the Health Utilities Index Mark 3 focusing on vision, speech, hearing, dexterity, ambulation, cognition, emotions, and pain. Each participant received an overall HRQOL utility score and individual domain subscores. These were correlated with demographic and treatment variables. Analysis was done using SPSS statistics (version 21). RESULTS: There were 125 patients with myelomeningocele, 25 with lipomyelomeningocele, and 9 with other dysraphisms. Among patients with myelomeningocele, 107 (86%) had CSF shunts in place, 14 (11%) had undergone Chiari malformation Type II decompression, 59 (47%) were community ambulators, and 45 (36%) were nonambulatory. Patients with myelomeningocele had significantly lower overall HRQOL scores than patients with closed spinal dysraphism. Among patients with myelomeningocele, younger patients had higher HRQOL scores. Patients with impaired bowel continence had lower overall HRQOL scores. History of a ventriculoperitoneal shunt was associated with worse HRQOL (overall score, ambulation, and cognition subscores). History of Chiari malformation Type II decompression was associated with worse overall, speech, and cognition scores. Patients who could ambulate in the community had higher overall and ambulation scores. A history of tethered cord release was correlated with lower pain subscore. No association was found between sex, race, insurance type, or bladder continence and HRQOL. CONCLUSIONS: Patients with myelomeningocele have significantly lower HRQOL scores than those with other spinal dysraphisms. History of shunt treatment and Chiari decompression correlate with lower HRQOL scores.

Cigarette smoke condensate affects monocyte interaction with endothelium.

OBJECTIVE: Circulating monocytes adhere to the endothelium and migrate into the intima contributing to atherosclerotic plaque growth. Cigarette smoke is a risk factor for atherosclerosis, but it is not completely known how it affects monocyte behavior in atherogenesis. METHODS: We studied the effects of cigarette smoke condensate (CSC) on human monocytes (HM) chemotaxis and transmigration through an endothelial cell (EC) monolayer. RESULTS: Pre-treatment with CSC caused a decrease in HM chemotaxis and transmigration (-55% and -18% vs control, p < 0.05, respectively), paralleled by a reduced expression of Rac 1 GTPase. On the contrary, direct exposure of both HM and EC to CSC increased (+23% vs control, p < 0.05) HM transmigration, paralleled by a strong stimulation of VCAM1 and ICAM1 expression by ECs, and by a slight increase in monocyte integrin expression. An enhancement of monocyte transmigration was obtained after the exposure of both HM and EC to medium conditioned by HM previously incubated with CSC (+265% vs control, p < 0.001). CSC showed a stimulatory effect on the expression by HM of TLR4, MCP1, IL8, IL1beta, and TNFalfa, which was ablated by pre treatment with PDTC. Incubation with neutralizing antibodies against both MCP1 or IL8 completely abolished the CSC-conditioned medium induced HM transmigration. CONCLUSIONS: CSC induces HM to release chemotactic factor(s), which amplify the recruitment and transmigration of inflammatory cells through EC, but CSC may also reduce HM migratory capacity. Therefore, exposure to CSC affects monocyte behavior and interaction with the endothelium, thus potentially facilitating and/or further aggravating the atherogenic process.

Therapy service use among individuals with fragile X syndrome: findings from a US parent survey.

BACKGROUND: Fragile X syndrome (FXS) is known to be associated with a range of developmental challenges, yet the occurrence and intensity of therapy services along with associated factors have not been determined. METHOD: In a US national survey, caregivers provided information regarding the therapy services received by their sons (n = 1013) and daughters (n = 283) with FXS (from birth to 63 years; mean = 15.6 years, SD = 10.6). Caregivers reported (1) type, (2) amount, (3) location, and (4) overall satisfaction with services. Associations with other child variables and family income were also examined. RESULTS: Key findings included that 72% of males and 47% of females were currently receiving at least one type of therapy service; the most common services for both males and females were speech-language therapy (ST) and occupational therapy (OT). Overall, males were more likely to receive therapy services as well as a greater number of services than females. Autism status was significantly associated with both males and females receiving ST and males receiving OT and behaviour management therapy. Therapies were provided in a variety of locations, and parents were generally satisfied with the amount and quality of therapy services. Age-related declines were evident in the use of services for both males and females, with very few individuals receiving any therapy services after 20 years of age. CONCLUSIONS: This study provides a baseline description of the current state of therapy services for children with FXS, laying a foundation for future research and recommendations for service provision and policy.

SYBR Green I: fluorescence properties and interaction with DNA.

In this study, we have investigated the fluorescence properties of SYBR Green I (SG) dye and its interaction with double-stranded DNA (dsDNA). SG/dsDNA complexes were studied using various spectroscopic techniques, including fluorescence resonance energy transfer and time-resolved fluorescence techniques. It is shown that SG quenching in the free state has an intrinsic intramolecular origin; thus, the observed >1,000-fold SG fluorescence enhancement in complex with DNA can be explained by a dampening of its intra-molecular motions. Analysis of the obtained SG/DNA binding isotherms in solutions of different ionic strength and of SG/DNA association in the presence of a DNA minor groove binder, Hoechst 33258, revealed multiple modes of interaction of SG inner groups with DNA. In addition to interaction within the DNA minor groove, both intercalation between base pairs and stabilization of the electrostatic SG/DNA complex contributed to increased SG affinity to double-stranded DNA. We show that both fluorescence and the excited state lifetime of SG dramatically increase in viscous solvents, demonstrating an approximate 200-fold enhancement in 100 % glycerol, compared to water, which also makes SG a prospective fluorescent viscosity probe. A proposed structural model of the SG/DNA complex is compared and discussed with results recently reported for the closely related PicoGreen chromophore.

Do uterine risk factors or lymph node metastasis more significantly affect recurrence in patients with endometrioid adenocarcinoma?

OBJECTIVES: Controversy continues over the importance of lymph node (LN) status in treating and predicting recurrence in endometrial cancer. Several predictive models are available which use uterine factors to stratify risk groups. Our objective was to determine how LN status affects recurrence and survival compared to uterine factors alone. METHODS: A retrospective review was performed of patients undergoing complete surgical staging for clinical stage 1 endometrioid adenocarcinoma of the uterus. Patients were assessed based on PORTEC 1 high intermediate risk (H-IR) criteria (2 factors : age>60, grade 3, >50% DOI), GOG-99 H-IR criteria (age >70+1 factor, age 50-70+2 factors, any age +3 factors: grade 2 or 3, LVSI, >50% DOI), and PORTEC 2 criteria. Rates of nodal involvement, recurrence rates, PFS, and OS were compared. RESULTS: We identified 352 clinical stage I patients with positive LN in 24% (87). 175 patients met PORTEC 1 eligibility and 66 met H-IR criteria. Rates of LN positivity were similar among groups (18.4% vs 19.7%, p=0.83) but recurrence rates were dissimilar (7.4% vs 27.3%, p=0.0004). Only 93 met PORTEC 2 criteria for treatment with no association between LN status, recurrence, and eligibility. 188 patients met H-IR eligibility criteria for GOG-99 with LN positive and recurrence rates higher in the H-IR group compared to GOG-99 eligible (34.6% vs 16.3%, p=0.0004, 28.3% vs. 10.6%, p=0.0002). CONCLUSIONS: Patients with H-IR disease based on uterine characteristics alone have substantial risk of nodal involvement. Knowledge of LN status may better define risk, prognosis, and postoperative treatment.

Characterization of PicoGreen interaction with dsDNA and the origin of its fluorescence enhancement upon binding.

PicoGreen is a fluorescent probe that binds dsDNA and forms a highly luminescent complex when compared to the free dye in solution. This unique probe is widely used in DNA quantitation assays but has limited application in biophysical analysis of DNA and DNA-protein systems due to limited knowledge pertaining to its physical properties and characteristics of DNA binding. Here we have investigated PicoGreen binding to DNA to reveal the origin and mode of PicoGreen/DNA interactions, in particular the role of electrostatic and nonelectrostatic interactions in formation of the complex, as well as demonstrating minor groove binding specificity. Analysis of the fluorescence properties of free PicoGreen, the diffusion properties of PG/DNA complexes, and the excited-state lifetime changes upon DNA binding and change in solvent polarity, as well as the viscosity, reveal that quenching of PicoGreen in the free state results from its intramolecular dynamic fluctuations. On binding to DNA, intercalation and electrostatic interactions immobilize the dye molecule, resulting in a >1000-fold enhancement in its fluorescence. Based on the results of this study, a model of PicoGreen/DNA complex formation is proposed.

Metal-enhanced PicoGreen fluorescence: application to fast and ultra-sensitive pg/ml DNA quantitation.

In this paper we provide both a theoretical and experimental analysis of the sensitivity of a DNA quantitation assay using a fluorescent chromophore which non-covalently binds dsDNA. It is well-known that the range of DNA concentrations available for fluorescence quantitation depends on the concentration of the chromophore, its affinity for nucleic acids, the binding site size on DNA and the ratio between the fluorescence intensity of the chromophore when bound to DNA compared to free chromophore in solution. We present experimental data obtained for a PicoGreen (PG)/DNA quantitation assay, which is in complete agreement with the results of our theoretical analysis. Experimentally measured PG-fluorescence intensity vs DNA concentration functions were fitted by a derived analytical expression, in which parameters of PG binding to DNA and chromophore fluorescence properties were included. We show that silver nanoparticles significantly increase the ratio between the fluorescence of PG bound to DNA and free PG, due to the metal-enhanced fluorescence effect (MEF), which enhances the lower limit of detectability of DNA concentrations by several orders of magnitude. An additional order of magnitude increase of PG/DNA assay sensitivity (~1 pg/ml) can be achieved by decreasing the PG concentration. We show herein that the use of MEF substrates in surface assays has a profound effect on assay sensitivity.