Suicide risk following ED presentation with self-harm varies by hospital

BACKGROUND

Patients presenting to Emergency Department (ED) with self-harm are recognized to be at high risk of suicide and other causes of death in the immediate period following ED presentation. It is also recognized that there is a large variation in the management and care pathways that these patients experience at EDs.

AIMS

This study asks if there is a significant variation in mortality risk according to hospital attended and if this is explained by differences in care management.

METHODS

Population-wide data from the Northern Ireland Registry of Self-Harm from April 2012 were linked with centrally held mortality records to December 2019, providing data on self-harm type and ED care. Cox proportional hazards models analyzed mortality risk, coded as suicide, all-external causes and all-cause mortality.

RESULTS

Analysis of the 64,350 ED presentations for self-harm by 30,011 individuals confirmed a marked variation across EDs in proportion of patients receiving mental health assessment and likelihood of admission to general and psychiatric wards. There was a significant variation in suicide risk following attendance according to ED attended with the three-fold range between the lowest (HRadj 0.32 95% CIs 0.16, 0.67) and highest. These differences persisted even after adjustment for patient characteristics, variation in types of self-harm, and care management at the ED.

CONCLUSIONS

This study suggests that while the management of self-harm cases in the ED is important, it is the availability and access to, and level of engagement with, the subsequent management and care in the community rather than the immediate care at EDs that is most critical for patients presenting to ED with self-harm. However, the initial care in ED is an important gateway in initiating referrals to these services.

Impact of the COVID-19 pandemic on self-harm and self-harm/suicide ideation: population-wide data linkage study and time series analysis

BACKGROUND

The COVID-19 pandemic and associated lockdowns were predicted to have a major impact on suicidal behaviour, including self-harm. However, current studies have produced contradictory findings with limited trend data.

AIMS

Nine years of linked individual-level administrative data were utilised to examine changes in hospital-presenting self-harm and ideation (thoughts of self-harm or suicide) before and during the pandemic.

METHOD

National self-harm registry data were linked to demographic and socioeconomic indicators from healthcare registration records (n = 1 899 437). Monthly presentations of self-harm or ideation were split (pre-COVID-19 restrictions: April 2012 to February 2020; and during restrictions: March to September 2020). Auto-regressive integrated moving average (ARIMA) models were trained in R taking into consideration trends and seasonal effects. Forecast ('expected') monthly values were compared with 'actual' values, stratified by demographic factors and method of harm.

RESULTS

The number of individuals presenting with self-harm or ideation dropped significantly at the beginning of the pandemic (March-May 2020), before returning mostly to expected trends from June 2020. Stratified analysis showed similar presentation trends across most demographic subgroups except for those aged over 65 years, living alone or in affluent areas, where presentations remained unaffected, and those aged under 16 years, where numbers presenting with self-harm or ideation increased above expected levels.

CONCLUSIONS

Although population trends show an overall drop in presentations before a return to 'normal' from June 2020, the demographic profile of those presenting with self-harm or ideation varied significantly, with increases in children under the age of 16 years. This highlights important potential target groups who may have been most negatively affected by the pandemic.

Mortality risk following self-harm in young people: a population cohort study using the Northern Ireland Registry of Self-Harm

BACKGROUND

Self-harm is a recognised predictor of suicide and is most common in those aged under 25 years. The aims of this study were to describe the characteristics of young people who present with self-harm; quantify the risk of suicide and other causes of death during follow up, and to identify factors associated with mortality risk.

METHODS

The Northern Ireland Registry of Self-Harm (NIRSH) is a national registry capturing complete data on all presentations made to the 12 Emergency Departments (EDs) in Northern Ireland (NI). Data relating to self-harm presentations registered in the NIRSH between 2012 and 2015 were linked to primary care registrations and death records up until 31st December 2018. Logistic regression was employed to examine the factors associated with self-harm. Cox regression was used to estimate mortality risk following self-harm and explore the associated risk factors.

RESULTS

The cohort consisted of 390,740 individuals aged 10-24 years registered with a General Practitioner (GP) in NI. During follow-up, 4,450 individuals presented with self-harm. Rates of self-harm were highest in females, those aged 20-24 years (ORadj  = 3.53, 95% CI 3.28-3.80, p < .001), and in the most deprived areas (ORadj  = 2.71, 95% CI 2.45-2.99, p < .001). Thirty five individuals who presented with self-harm died by suicide, accounting for 23% of all suicide deaths in the cohort. Suicide risk was increased 19-fold in those who presented with self-harm after adjustment for age, sex and area-level factors (HRadj  = 19.00, 95% CI 12.80-28.21, p < .001). Increased suicide risk was observed in males (HRadj  = 2.04, 95% CI 0.99-4.23, p = .05) and those using more violent methods of self-injury (HRadj  = 3.89, 95% CI 1.65-9.13, p < .001).

CONCLUSIONS

Young people who self-harm are at a significantly greater risk of suicide. Almost a quarter of young people who died by suicide in NI had presented to EDs with self-harm, highlighting that the ED may provide a nodal point of intervention among a typically hard to identify and reach population.

Emergency department presentations with suicide and self-harm ideation: a missed opportunity for intervention?

AIMS

Suicidal ideation constitutes a central element of most theories of suicide and is the defining facet separating suicide from other causes of death such as accidents. However, despite a high worldwide prevalence, most research has focused on suicidal behaviours, such as completed suicide and suicide attempts, while the greater proportion who experienced ideation, which frequently precedes suicidal behaviour, have received much less attention. This study aims to examine the characteristics of those presenting to EDs with suicidal ideation and quantify the associated risk of suicide and other causes of death.

METHODS

Retrospective cohort study was performed based on population-wide health administration data linked to data from the Northern Ireland Registry of Self-Harm and centrally held mortality records from April 2012 to December 2019. Mortality data, coded as suicide, all-external causes and all-cause mortality were analysed using Cox proportional hazards. Additional cause-specific analyses included accidental deaths, deaths from natural causes and drug and alcohol-related causes.

RESULTS

There were 1,662,118 individuals aged over 10 years, of whom 15,267 presented to the ED with ideation during the study period. Individuals with ideation had a 10-fold increased risk of death from suicide (hazard ratio [HR_adj] = 10.84, 95% confidence interval [CI] 9.18, 12.80) and from all-external causes (HR_adj = 10.65, 95% CI 9.66, 11.74) and a threefold risk of death from all-causes (HR_adj = 3.01, 95% CI 2.84, 3.20). Further cause-specific analyses indicated that risk of accidental death (HR_adj = 8.24, 95% CI 6.29, 10.81), drug-related (HR_adj = 15.17, 95% CI 11.36, 20.26) and alcohol-related (HR_adj = 10.57, 95% CI 9.07, 12.31) has also significantly increased. There were few socio-demographic and economic characteristics that would identify which of these patients are most at risk of suicide or other causes of death.

CONCLUSIONS

Identifying people with suicidal ideation is recognized to be both important but difficult in practice; this study shows that presentations to EDs with self-harm or suicide ideation represent an important potential intervention point for this hard-to-reach vulnerable population. However, and unlike individuals presenting with self-harm, clinical guidelines for the management and recommended best practice and care of these individuals are lacking. Whilst suicide prevention may be the primary focus of interventions aimed at those experiencing self-harm and suicide ideation, death from other preventable causes, especially substance misuse, should also be a cause of concern.

Impact of the COVID-19 pandemic on psychotropic medication uptake: time-series analysis of a population-wide cohort

BACKGROUND

The COVID-19 pandemic and associated lockdowns were predicted to have a major impact on mental health, however current studies have produced contradictory findings with limited longitudinal data.

AIMS

Nine years of linked, individual-level administrative data were used to examine changes in psychotropic medication uptake before and during the pandemic.

METHOD

Medication data from a population-wide prescribing database were linked to demographic and socioeconomic indicators from healthcare registration records (n = 1 801 860). Monthly prescription uptake was split (pre-restrictions: January 2012 to February 2020 and during restrictions: March to October 2020). Auto regressive integrated moving average (ARIMA) models were trained in R taking into consideration trends and seasonal effects. Forecast ('expected') monthly values were compared with 'actual' values, stratified by demographic factors.

RESULTS

Over the study period 38.5% of the study population were in receipt of ≥1 psychotropic medication. Uptake of these medications have been following a strong upward trend since January 2012. In March 2020 uptake of all medications increased beyond expected values, returning to expected trends from May 2020 for antidepressants, anxiolytics and antipsychotics. In the 8 months during restrictions uptake of hypnotic medication was 12% higher than expected among those <18 years, and anxiolytic medication higher than expected in those >65 years.

CONCLUSIONS

Results suggest an initial 'stockpiling' of medications in March 2020 before trends mostly returned to expected levels. The anticipated tsunami of mental ill health is not yet manifest in psychotropic medication uptake. There are indications of increased anxiety and sleep difficulties in some subgroups, although these conditions may resolve as we emerge from the pandemic without need for psychiatric intervention.

Impact of the COVID-19 pandemic on Self-Harm and self-harm/suicide Ideation and subsequent mortality in Northern Ireland: a longitudinal, population-wide data linkage study

ObjectiveTo utilise Northern Ireland’s unique population-wide registry of self-harm and self-harm/suicide ideation, linked to other administrative health and death records, to examine the impact of the COVID-19 pandemic and related restrictions on presentations for self-harm/ideation and subsequent mortality risk. ApproachLongitudinal, population-wide registry data on all presentations to Emergency Departments for self-harm (SH) or self-harm/suicide ideation (I) (Apr 2102-2020) were linked to primary care registration and death records within Northern Ireland Trust Research Environment (NITRE). Data were divided pre-restrictions (Apr 2012-Feb 2020) and during-restrictions (Mar 2020-Sept 2020). Raw pre- and during numbers were compared. Auto Regressive Integrated Moving Average (ARIMA) models were trained considering trends and seasonal effects. Monthly forecasts were compared to actual numbers, at population level and within sociodemographic groups (gender, age, method). Survival analysis examined risk all-cause/suicide mortality after presenting with SH/I before versus during restrictions. ResultsMar and Apr 2020 saw 15.3% and 32.9% drop respectively in the total number of presentations for SH/I. From May 2020 numbers returned to within 2% of the monthly average. The sharp decrease in Mar/Apr 2020 was observed in both males and females but varied by age sub-categories. Presentations in those aged >64years remained as expected and presentations in the <16 years were higher than expected, compared to a decrease in presentations in those aged 16-64years. The restrictions impacted on variations by method of harm and by hospital. Suicide mortality given previous SH/I appears to increase slightly for males during the COVID restrictions with further analysis underway. ConclusionAlthough at a population level it looks like Emergency Department presentations for SH/I decreased in first 2 months of the pandemic before returning to “normal”, the presentation profile changed dramatically by age, method and hospital. Further ARIMA predictive modelling and survival analysis are underway to explore subsequent mortality risk.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Risk of repetition and subsequent self-harm following presentation to hospital with suicidal ideation: A longitudinal registry study

BACKGROUND

Few studies have focused on those who present to hospital with suicidal thoughts (suicidal ideation). The aim of this study was to establish the risk of repeat presentation to hospital following suicidal ideation and to identify factors which were associated with further ideation or subsequent self-harm.

METHODS

Data were obtained from the Northern Ireland Registry of Self-harm. Risk of repeat presentation following hospital-presenting ideation was analysed using Kaplan Meier analyses, specifically cox proportional hazard models.

FINDINGS

During the period April 2014 to March 2019, a total of 14,695 presentations to hospital due to suicidal ideation were made in Northern Ireland. The cumulative incidence of repeat presentation to hospital was 40·5% within five years, with an 18·3% risk of subsequent self-harm. Previous ideation had the strongest association with repeat presentation. There was evidence of recidivism considering further ideation, with an increased risk according to number of previous presentations. In contrast, risk of subsequent self-harm was highest after the first or second presentation. Male gender and alcohol were associated with further ideation, while females and young people were more likely to re-present with self-harm.

INTERPRETATION

The findings indicate that individuals who present to hospital with suicidal ideation are at risk of repeat presentation and future self-harm, however clinical guidelines do not specifically address hospital-presenting ideation. The transition from ideation to suicidal behaviour is important to consider and research could inform effective screening and early intervention measures.

ROLE OF FUNDING

The Northern Ireland Registry of Self-harm is funded by the Public Health Agency, Northern Ireland.

Suicide following presentation to emergency departments with suicidal ideation: a population-wide study

Background Little is known about the association between suicide ideation and completed suicide. As NI has the highest suicide rate in the UK and Ireland it is vital to understand who is most at risk in order to target prevention strategies effectively. Aim To explore the risk factors for completed suicide following presentation with suicide ideation. Methods The Northern Ireland Registry of Self-Harm and Suicide Ideation contains information on all presentations to all Emergency Departments in NI for self-harm and suicide ideation. Data from 2012-2015 were linked to centralised electronic data relating to primary care, prescribed medication and mortality records. Initial analyses were completed to explore the profile of those who present with suicide ideation, and logistic regression was utilised to examine the likelihood of mortality post presentation. Cox regression was utilised to examine the factors associated with completed suicide following presentation with ideation. Results The cohort consisted of 1,483,435 individuals born or resident in NI from 1st January 1970 until 31st December 2015 (maximum age in 2015, 45 years). Between 2012-2015, 4,975 (0.3%) individuals presented with suicide ideation and 583 (0.04%) individuals died by suicide. Ideation is more likely in men compared to women (OR=1.87, 95%CI 1.76,1.98), in those aged 18-24 years, and in more deprived individuals. Of those who presented with ideation, 66 (1.3%) subsequently died by suicide. In fully-adjusted models, those who presented with suicide ideation were 25 times more likely to die by suicide compared to those who did not (HR=25.0, 95%CI 19.3,32.5). Amongst suicide ideators, male gender (HR=2.67, 95% CI 1.39,5.10) and multiple presentations (HR=1.95, 95% CI 1.09,3.50) were associated with the greatest risk of death by suicide. Conclusion These findings could help emergency department staff identify individuals at greatest risk of suicide and could be utilised in the development of targeted intervention strategies.

What happens after self-harm? An exploration of self-harm and suicide using the Northern Ireland Registry of Self-Harm

Background Suicide is a major public health concern and Northern Ireland (NI) has the highest rate of both self-harm and suicide in the UK and Ireland. In order to target prevention strategies effectively, it is vital to understand who is most at risk. Aim To explore the risk factors for completed suicide following presentation with self-harm. Methods The Northern Ireland Registry of Self-Harm (NIRSH) collects information on all self-harm and suicide ideation presentations to all Emergency Departments in NI. NIRSH data from 2012-2015 was linked to centralised electronic data relating to primary care, prescribed medication and mortality records. Logistic regression was employed to quantify the likelihood of mortality with adjustment for factors associated with mental ill health and suicide risk, and Cox regression was used to explore which characteristics of those who self-harm are most associated with risk of suicide. Results The cohort consisted of all 1,483,435 individuals born or resident in NI from 1st January 1970 until 31st December 2015 (maximum age in 2015, 45 years). During the follow-up period, 12,327 (0.8%) individuals presented with self-harm and 892 (0.1%) died by suicide. Rates of self-harm were equivalent for males and females with highest rates observed in the 18-24 years age group, and more common in deprived than affluent areas (OR=3.42, 95%CI 3,21, 3.65). Most individuals self-harmed via self-poisoning with psychotropic medications (71.5%), followed by self-injury with a sharp object (21.7%). Although only 162 (1.3%) of those who presented with self-harm went on to die by suicide, those who presented with self-harm were 24 times more likely to die by suicide compared to those who did not present with self-harm after adjustment for age and sex (HR=24.3, 95%CI 20.46,28.76). Conclusion This constitutes the first population-wide study of self-harm in the UK and could be utilised to inform suicide prevention strategies.

A two-step fluorinase enzyme mediated 18F labelling of an RGD peptide for positron emission tomography

Fluorine-18 radiolabelling of a peptide is conducted in water (pH 7.8 and 37 °C) using the fluorinase enzyme and a ‘click’ reaction.

Driving forces underlying the formation of chiral domains of fluorinated diacids on graphite

The role of intermolecular interactions, molecule-substrate interactions, and molecular chirality in the construction of 2-D surface architectures is the subject of much current interest. A racemic mixture of long chain hydrocarbons was synthesized with terminal carboxylic acid functionalities at each end and two amide linkages in the central region of the molecule on either side of two F-containing chiral centers. Using scanning tunnelling microscopy (STM), we have examined how the functionality of these molecules influences their self-assembly on a highly oriented pyrolytic graphite (HOPG) surface. The key factors determining the nature of ordered domains have been identified.

Human immunodeficiency virus type 1 Gag-specific vaginal immunity and protection after local immunizations with sindbis virus-based replicon particles

The majority of human immunodeficiency virus (HIV) infections occur through vaginal and rectal transmission. In seeking a safe, nonreplicating gene-delivery vector that can induce mucosal and systemic immune responses and protection, Sindbis virus-based replicon particles expressing HIV-1 Gag (SIN-Gag) were developed. In mice, after nasal or intramuscular immunization with SIN-Gag and vaginal challenge with vaccinia virus (VV) expressing HIV-1 Gag (VV-Gag), CD8(+) T cell-mediated responses were detected locally, in the vaginal mucosa and in the draining iliac lymph nodes (ILNs), and systemically, in the spleen. However, the mice were not protected against VV-Gag replication in the ovaries. In contrast, after vaginal or rectal immunization with SIN-Gag and vaginal challenge with VV-Gag, despite lower local CD8(+) T cell-mediated responses in the vaginal mucosa and ILNs, the mice were protected against VV-Gag replication in the ovaries. Therefore, local immunization with SIN-Gag induced both local mucosal cell-mediated responses and protection.

Mucosal immunization with HIV-1 gag DNA on cationic microparticles prolongs gene expression and enhances local and systemic immunity

There is an urgent need to develop vaccines against transmission of HIV through the vaginal and rectal mucosa. In the present study we tested the ability of DNA encoding HIV-1 gag adsorbed onto the surface of cationic polylactide co-glycolide microparticles (PLG-DNA) to induce local and systemic gag-specific immunity following mucosal delivery. We found gag-specific cell- and antibody-mediated responses in local as well as systemic lymphoid tissues following intranasal (IN) immunizations with PLG-DNA but not with naked DNA. IN immunizations with PLG-DNA, but not naked DNA, induced prolonged expression of gag protein in local and systemic lymphoid tissues. These data have important implications for DNA vaccine development.

Isolation of an aldehyde dehydrogenase involved in the oxidation of fluoroacetaldehyde to fluoroacetate in Streptomyces cattleya

Streptomyces cattleya is unusual in that it produces fluoroacetate and 4-fluorothreonine as secondary metabolites. We now report the isolation of an NAD(+)-dependent fluoroacetaldehyde dehydrogenase from S. cattleya that mediates the oxidation of fluoroacetaldehyde to fluoroacetate. This is the first enzyme to be identified that is directly involved in fluorometabolite biosynthesis. Production of the enzyme begins in late exponential growth and continues into the stationary phase. Measurement of kinetic parameters shows that the enzyme has a high affinity for fluoroacetaldehyde and glycoaldehyde, but not acetaldehyde.

Induction of potent immune responses by cationic microparticles with adsorbed human immunodeficiency virus DNA vaccines

The effectiveness of cationic microparticles with adsorbed DNA at inducing immune responses was investigated in mice, guinea pigs, and rhesus macaques. Plasmid DNA vaccines encoding human immunodeficiency virus (HIV) Gag and Env adsorbed onto the surface of cationic poly(lactide-coglycolide) (PLG) microparticles were shown to be substantially more potent than corresponding naked DNA vaccines. In mice immunized with HIV gag DNA, adsorption onto PLG increased CD8(+) T-cell and antibody responses by approximately 100- and approximately 1,000-fold, respectively. In guinea pigs immunized with HIV env DNA adsorbed onto PLG, antibody responses showed a more rapid onset and achieved markedly higher enzyme-linked immunosorbent assay and neutralizing titers than in animals immunized with naked DNA. Further enhancement of antibody responses was observed in animals vaccinated with PLG/DNA microparticles formulated with aluminum phosphate. The magnitude of anti-Env antibody responses induced by PLG/DNA particles was equivalent to that induced by recombinant gp120 protein formulated with a strong adjuvant, MF-59. In guinea pigs immunized with a combination vaccine containing HIV env and HIV gag DNA plasmids on PLG microparticles, substantially superior antibody responses were induced against both components, as measured by onset, duration, and titer. Furthermore, PLG formulation overcame an apparent hyporesponsiveness of the env DNA component in the combination vaccine. Finally, preliminary data in rhesus macaques demonstrated a substantial enhancement of immune responses afforded by PLG/DNA. Therefore, formulation of DNA vaccines by adsorption onto PLG microparticles is a powerful means of increasing vaccine potency.

Controlled release of recombinant insulin-like growth factor from a novel formulation of polylactide-co-glycolide microparticles

The purpose of the current study was to develop a controlled-release delivery system for recombinant insulin-like growth factor (rhIGF-I). Polylactide-co-glycolide (PLG) microparticles with entrapped rhIGF-I were prepared by a novel emulsion based solvent evaporation process. Microparticles with two loading levels of rhIGF-I were prepared (4 and 20% w/w). The integrity of released rhIGF-I was characterized by RP-HPLC, SDS-PAGE and a bioactivity assay. In vitro and in vivo release profiles of rhIGF-I from these microparticles were also evaluated. Reproducible batches of microparticles with 4% and 20% w/w loading of rhIGF-I were prepared, with excellent encapsulation efficiency (81 and 85% of total protein respectively entrapped). The protein retained integrity after the microencapsulation process as evaluated by RP-HPLC, SDS-PAGE and bioactivity assay. The in vitro profiles exhibited a significant burst release of rhIGF-I (20-30%), followed by controlled release of protein for up to 28 days. A similar level of burst release was observed in vivo, followed by controlled release of protein for 14-18 days. In addition, there was a surprisingly close correlation between in vitro and in vivo release rates. PLG microparticles with entrapped rhIGF-I are a promising delivery system which may allow rhIGF-I to be used for a broad range of therapeutic indications.

Plasmid DNA adsorbed onto cationic microparticles mediates target gene expression and antigen presentation by dendritic cells

Dendritic cells (DC) play a key role in antigen presentation and activation of specific immunity. Much current research focuses on harnessing the potency of DC for vaccines, gene therapy, and cancer immunotherapy applications. However, DC are not readily transfected in vitro by traditional nonviral techniques. A novel DNA vaccine formulation was used to determine if DC are transfected in vitro. The formulation consists of plasmid DNA adsorbed on to cationic microparticles composed of the biodegradable polymer polylactide-co-glycolide (PLG) and the cationic surfactant, cetyltrimethylammonium bromide (CTAB). Using preparations of fluorescent-labeled plasmid DNA formulated on PLG-CTAB microparticles to study internalization by macrophages and dendritic cells in vitro and in vivo, we found that most, but not all, of the fluorescence was concentrated in endosomal compartments. Furthermore, uptake of plasmid DNA encoding HIV p55 gag adsorbed to PLG-CTAB microparticles by murine bone marrow-derived dendritic cells resulted in target gene expression, as detected by RT-PCR. The antigen was subsequently processed and presented, resulting in stimulation of an H-2kd-restricted, gag-specific T cell hybridoma. Activation of the hybridoma, detected by IL-2 production, was dose-dependent in the range of 0.1-20 microg DNA (10-2000 microg PLG) and was sustained up to 5 days after transfection. Thus, adsorption of plasmid DNA on PLG-CTAB microparticles provides a potentially useful nonviral approach for in vitro transfection of dendritic cells. Gene Therapy (2000) 7, 2105-2112.

Genetically detoxified mutants of heat-labile enterotoxin from Escherichia coli are effective adjuvants for induction of cytotoxic T-cell responses against HIV-1 gag-p55

There is an urgent need for prophylactic and therapeutic vaccines against human immunodeficiency virus (HIV). Mucosal immunization strategies have great potential to elicit both mucosal and systemic cellular immunity required to protect against HIV-induced acquired immune deficiency syndrome (AIDS). However, mucosal immunizations with soluble protein antigens generally require adjuvants. In this study, we tested two mutants of the heat-labile enterotoxin (LT) from Escherichia coli, LTK63: with no measurable ADP-ribosyltransferase activity, and LTR72: with residual ADP-ribosyltransferase activity, as mucosal adjuvants for induction of cytotoxic T lymphocyte (CTL) responses to coadministered HIV gag p55 protein. We found that intranasal (i.n.) immunizations with HIV gag p55 protein coadministered with LTK63 or LTR72 induced systemic CTL responses comparable to that obtained following intramuscular (i. m.) immunizations with the same adjuvants. Moreover, oral coadministration of LTR72, but not LTK63, resulted in local as well as systemic p55-specific CTL responses in mesenteric lymph nodes (MLN) and spleens (SP) of the immunized mice. These data have important implications for current efforts to develop a safe vaccine against HIV.

Transcutaneous immunization with bacterial ADP-ribosylating exotoxins, subunits, and unrelated adjuvants

We have recently described a needle-free method of vaccination, transcutaneous immunization, consisting of the topical application of vaccine antigens to intact skin. While most proteins themselves are poor immunogens on the skin, we have shown that the addition of cholera toxin (CT), a mucosal adjuvant, results in cellular and humoral immune responses to the adjuvant and coadministered antigens. The present study explores the breadth of adjuvants that have activity on the skin, using diphtheria toxoid (DTx) and tetanus toxoid as model antigens. Heat-labile enterotoxin (LT) displayed adjuvant properties similar to those of CT when used on the skin and induced protective immune responses against tetanus toxin challenge when applied topically at doses as low as 1 microg. Interestingly, enterotoxin derivatives LTR192G, LTK63, and LTR72 and the recombinant CT B subunit also exhibited adjuvant properties on the skin. Consistent with the latter finding, non-ADP-ribosylating exotoxins, including an oligonucleotide DNA sequence, as well as several cytokines (interleukin-1beta [IL-1beta] fragment, IL-2, IL-12, and tumor necrosis factor alpha) and lipopolysaccharide also elicited detectable anti-DTx immunoglobulin G titers in the immunized mice. These results indicate that enhancement of the immune response to topical immunization is not restricted to CT or the ADP-ribosylating exotoxins as adjuvants. This study also reinforces earlier findings that addition of an adjuvant is important for the induction of robust immune responses to vaccine antigens delivered by topical application.

Biosynthetic studies on the tropane ring system of the tropane alkaloids from Datura stramonium

Isotopic labelling experiments have been carried out in Datura stramonium root cultures with the following isotopically labelled precursors; [2H3]- [2-13C, 2H3]-, [1-13C, 18O2]-acetates, 2H2O, [2H3-methyl]-methionine, [2-13C]-phenyllactate, [3-2H]-tropine and [2'-13C, 3-2H]-littorine. The study explored the incorporation of isotope into the tropane ring system of littorine 1 and hyoscyamine 2 and revealed that deuterium from acetate is incorporated only into C-6 and C-7, and not into C-2 and C-4 as previously reported. Oxygen-18 was not retained at a detectable level into the C(3)-O bond from [1-13C, 18O2]-acetate. The intramolecular nature of the rearrangement of littorine 1 to hyoscyamine 2 is revealed again by a labelling study using [2'-13C, 3-2H]-littorine, [2-13C]-phenyllactate and [3-2H]-tropine.

Cationic microparticles: A potent delivery system for DNA vaccines

An approach involving the preparation of biodegradable microparticles with a cationic surface was developed to improve the delivery of adsorbed DNA into antigen-presenting cells after i.m. injection. The microparticles released intact and functional DNA over 2 weeks in vitro. In addition, the microparticles induced higher levels of marker gene expression in vivo. After i.m. immunization, the microparticles induced significantly enhanced serum antibody responses in comparison to naked DNA. Moreover, the level of antibodies induced by the microparticles was significantly enhanced by the addition of a vaccine adjuvant, aluminum phosphate. In addition, in contrast to naked DNA, the cationic microparticles induced potent cytotoxic T lymphocyte responses at a low dose.

Advances in vaccine adjuvants

Currently, aluminum salts and MF59 are the only vaccine adjuvants approved for human use. With the development of new-generation vaccines (including recombinant subunit and mucosal vaccines) that are less immunogenic, the search for more potent vaccine adjuvants has intensified. Of the novel compounds recently evaluated in human trials, immunostimulatory molecules such as the lipopolysaccharide derived MPL and the saponin derivative QS21 appear most promising, although doubts have been raised as to their safety in humans. Preclinical work with particulate adjuvants, such as the MF59 microemulsion and lipid-particle immune-stimulating complexes (Iscoms), suggest that these molecules are also potent elicitors of humoral and cellular immune responses. In addition, preclinical data on CpG oligonucleotides appear to be encouraging, particularly with respect to their ability to selectively manipulate immune responses. While all these adjuvants show promise, further work is needed to better define the mechanisms of adjuvant action. Ultimately, the development of more potent adjuvants may allow vaccines to be used as therapeutic, rather than prophylactic, agents.

Effects of lasalocid on performance of lactating dairy cows

Sixty lactating dairy cows (30 multiparous and 30 primiparous) were used in a completely randomized block design to determine the effect of lasalocid supplementation on dairy cow performance. Starting wk 2 prepartum and lasting through wk 17 of lactation, cows received one of three experimental diets. The experimental total mixed rations were control (CD), control + 10 mg/kg of lasalocid (CD + 10) and control + 20 mg/kg of lasalocid (CD + 20). The alfalfa-based control diet (40:60; forage:concentrate) was formulated to contain 18% crude protein, 35% nonstructural carbohydrates, 31% neutral detergent fiber, and 6.6% ether extract. Lasalocid supplementation linearly decreased dry matter intake (DMI) without affecting milk production or milk composition. Mean milk production and percentages of fat and protein were 30.0, 30.8, and 28.6; 3.56, 3.51, and 3.63; 3.06, 3.05, and 3.09; respectively for treatments CD, CD + 10, and CD + 20. Lasalocid supplementation decreased milk urea N (MUN) when compared to control cows, and increasing supplementation caused a significant linear decrease in MUN. For the primiparous cows, lasalocid supplementation decreased DMI and MUN while increasing body condition score and feed efficiency. Results from this study indicate that lactating dairy cows and, in particular, primiparous cows may benefit from lasalocid supplementation in terms of more efficient utilization of nutrients for milk production, reduced MUN levels, reduced body condition loss, and higher margin over feed cost.

Intranasal immunization with recombinant gD2 reduces disease severity and mortality following genital challenge with herpes simplex virus type 2 in guinea pigs

The ability of a genetically detoxified mutant of heat labile enterotoxin (LTK63) to act as a mucosal adjuvant following intranasal immunization with recombinant gD2 has previously been reported in mice [Ugozzoli M, O'Hagan DT, Ott GS. Intranasal immunization of mice with herpes simplex virus type 2 recombinant gD2: the effect of adjuvants on mucosal and serum antibody responses. Immunol 1998;93:563-571.]. In the current studies, these observations were extended to the guinea pig model. Immunized guinea pigs were subsequently challenged intravaginally with HSV-2. Intranasal immunization with gD2 and LTK63 induced a significant reduction in disease severity and a reduction in mortality. However, only intramuscular immunization with a potent adjuvant (MF59) induced protection against the incidence of disease.

The biosynthetic relationship between littorine and hyoscyamine in transformed roots of Datura stramonium

The metabolic relationship between littorine and hyoscyamine has been monitored in transformed roots of Datura stramonium. Quantification by GC of unlabelled littorine and by GCMS of ¹³C-labelled littorine demonstrated that exogenously added littorine (0.1 mM) was significantly metabolised (35%) to hyoscyamine. In contrast, exogenously added hyoscyamine was not metabolised to littorine, indicating that this conversion is irreversible. The conversion of littorine to hyoscyamine was suppressed by P-450 oxidase inhibitors (particularly clotrimazole), implicating the involvement, at least in part of a cytochrome P-450 activity operating hyoscyamine biosynthesis.

The preparation and characterization of polymeric antigen delivery systems for oral administration

Although polymeric delivery systems are well established for the oral administration of conventional drugs, they have not yet been commercially developed for vaccine delivery. The problems inherent with the oral route of delivery, including low pH, gastric enzymes, rapid transit and poor absorption of large molecules, has made the goal of oral delivery of antigens very challenging. Nevertheless, several polymeric delivery systems for the oral administration of vaccines are currently being evaluated, including microencapsulation in poly(lactide-co-glycolides), alginates, polyanhydrides, starch, polymethacrylates, polyamino acids and enteric coating polymers. These approaches are designed to protect the antigen in the gut, to target the antigen to the gut-associated lymphoid tissue, or to increase the residence time of the antigen in the gut through bioadhesion. Each of these approaches is discussed in relation to antigen encapsulation and integrity, process reproducibility, ease of preparation and encapsulation efficiency. Potential problems associated with the scale-up of these approaches are also briefly addressed. Of particular relevance are the prospects for the application of these formulation processes for commercial development.

A comparison of biodegradable microparticles and MF59 as systemic adjuvants for recombinant gD from HSV-2

A recombinant form of glycoprotein D from herpes simplex virus type-2 (gD2) was encapsulated into polylactide-co-glycolide (PLG) microparticles using a previously established solvent evaporation technique. The mean size of the microparticles was about 1 micron and high encapsulation efficiency of the antigen was achieved (70-80%). The microparticles were administered intramuscularly to Balb/C mice and the immune responses were compared with those obtained with the oil in water adjuvant MF59. The serum IgG response to gD2 induced by the microparticles was comparable with that induced by MF59. The serum neutralization titres were also comparable for microparticles and the emulsion. However, the microparticles induced a higher IgG2a isotype response and a more potent serum IFN-gamma response than MF59, suggesting a more Th1 type of response. The MF59 induced higher levels of serum IL-4 and IL-5 cytokines, suggesting a more Th2 type of response.

Interferons impair early transgene expression by adenovirus-mediated gene transfer in muscle cells

Recombinant adenovirus (AVR) promises to be an efficient vector in gene therapy for neuromuscular diseases, but in preclinical experiments the expression of therapeutic genes is shorter lived in immunocompetent animals than in immunocompromised hosts. Interferons (IFN), which are known to have a role both in early antiviral activity and in late cytotoxic immunoreaction against the virus or transduced cells, may influence the efficiency of gene transfer. In this study we investigated the role of IFNs in determining the efficiency of gene transfer by AVR. AVRs expressing beta-galactosidase (beta-gal) from either a cytomegalovirus (CMV) or a troponin-I promoter were used. Muscle cells were infected by AVR after exposure to various IFNs. The alphaIFN treatment significantly reduced (up to fivefold) the CMV promoter-driven gene expression in muscle cells in vitro and in immature muscles in vivo, while the least effective inhibitor was betaIFN. The decrease in gene expression by IFNs was more pronounced with the CMV-driven transgene than troponin-I promoter-driven one and was due to a decrease in transcript level. Intrinsic IFNs that are triggered by AVR administration can decrease the efficiency of gene transfer in muscle cells. Therefore the use of muscle specific promoters in AVR and/or IFN inhibitory agents will likely improve the prospects of effective gene therapy by AVR.

Evidence that the homeodomain protein Gtx is involved in the regulation of oligodendrocyte myelination

We have investigated the patterns of postnatal brain expression and DNA binding of Gtx, a homeodomain transcription factor. Gtx mRNA accumulates in parallel with the RNAs encoding the major structural proteins of myelin, myelin basic protein (MBP), and proteolipid protein (PLP) during postnatal brain development; Gtx mRNA decreases in parallel with MBP and PLP mRNAs in the brains of myelin-deficient rats, which have a point mutation in the PLP gene. Gtx mRNA is expressed in differentiated, postmitotic oligodendrocytes but is not found in oligodendrocyte precursors or astrocytes. These data thus demonstrate that Gtx is expressed uniquely in differentiated oligodendrocytes in postnatal rodent brain and that its expression is regulated in parallel with the major myelin protein mRNAs, encoding MBP and PLP, under a variety of physiologically relevant circumstances. Using a Gtx fusion protein produced in bacteria, we have confirmed that Gtx is a sequence-specific DNA-binding protein, which binds DNA sequences containing a core AT-rich homeodomain binding site. Immunoprecipitation of labeled DNA fragments encoding either the MBP or PLP promoter regions with this fusion protein has identified several Gtx-binding fragments, and we have confirmed these data using an electrophoretic mobility shift assay. In this way we have identified four Gtx binding sites within the first 750 bp of the MBP promoter and four Gtx binding sites within the first 1. 3 kb of the PLP promoter. In addition, inspection of the PLP promoter sequence demonstrates the presence of six additional Gtx binding sites. These data, taken together, strongly suggest that Gtx is important for the function of differentiated oligodendrocytes and may be involved in the regulation of myelin-specific gene expression.

Multifocal contact lenses--look again!

In this study aspheric progressive simultaneous vision multifocal contact lenses demonstrated up to 1.8 lines of lost distance visual acuity, reduction in distance and near stereoacuity, and mild to moderate difficulties with night driving, ghost images, haloes and glare. These deficits, which can be minimized with certain designs and lighting conditions, seem to be well tolerated by highly motivated young presbyopes. Combining different styles of multifocal contact lenses in the two eyes simultaneously may be another method of further improving performance. Depending on the design, the performance of these lenses approaches that of spectacle correction in terms of contrast sensitivity and near visual acuity, the latter being important to this population. Both test lenses proved easy to fit based on the manufacturer's recommendations alone. Although multifocal contact lenses may not be suitable for people whose occupations require precise distance visual acuity and stereopsis, our results suggest that they may be an acceptable alternative for a substantial proportion of presbyopes who desire the convenience, performance and improved cosmesis of contact lenses.

Synthetic peptides entrapped in microparticles can elicit cytotoxic T cell activity

Peptides from Plasmodium berghei circumsporozoite protein (CS) and influenza A virus nucleoprotein (NP) were entrapped in microparticles prepared from poly (lactide-co-glycolide) polymers, and the microparticles were administered parenterally to mice. After immunization with single or multiple doses, splenocytes were tested for a cytotoxic T cell (CTL) response and high levels of CTL activity were detected. The CTL induced were CD8+, MHC class I restricted, and could recognize virus infected cells. Peptide entrapped in microparticles of mean size < 500 nm were better inducers of CTL than larger microparticles (mean > 2 microns and above). Microparticles could also be used to deliver lipid modified peptides (lipopeptides) and elicited higher levels of cytolytic activity than either free peptide in microparticles or lipopeptide alone. Microparticles provide a novel way of inducing a CTL response using synthetic peptides.

Comparison of adjuvant formulations for cytotoxic T cell induction using synthetic peptides

We have investigated the capacity of synthetic peptides delivered in different adjuvant formulations to induce cytotoxic T lymphocyte (CTL) responses to a class I H-2Kd-restricted Plasmodium berghei circumsporozoite epitope, CS 252-260. Using three immunogen formulations: soybean emulsion; Montanide ISA720; and lipopeptide (P3-CS), we first evaluated the effects of immunization routes on CTL induction. No CTL response was induced in mice immunized s.c. or i.p. with CS peptide formulated in soybean emulsion. In contrast, immunization with lipopeptide P3-CS either s.c. or i.p. effectively primed for CTL. Interestingly, CS peptide emulsified in Montanide ISA720 induced a CTL response only when delivered s.c. and not i.p., indicating the critical influence of immunization routes on CTL induction. We then compared the effectiveness of eight adjuvant formulations to induce CTL response following a single s.c. immunization. Notably, lipopeptide P3-CS and CS peptide admixed with P3 or POE lipid molecules stimulated a vigorous CTL response. However, only mice immunized with P3-CS and CS peptide admixed with P3 molecule generated long-lived CTL which persisted in vivo for 5 months. Thus, based on a simultaneous comparison of the different adjuvant formulations, we demonstrated that the conjugated and unconjugated P3 lipopeptides were the most effective immunogens for eliciting primary and memory CTL in mice.

The biosynthesis of monensin-A: thymine, beta-aminoisobutyrate and methacrylate metabolism in Streptomyces cinnamonensis

Feeding experiments with isotopically labelled samples of [13C,2H3-methyl]-thymine, (R,S)-[I-13C]- and (R,S-[13C-methyl]-beta-aminoisobutyrates into monensin-A demonstrate that these metabolites can all contribute to the methylmalonyl-CoA pool in Streptomyces cinnamonensis, and implicate DNA catabolism as a contributory metabolic source of propionate carbon atoms for secondary metabolic biosynthesis. Further, these labelled compounds were unexpectedly incorporated into the butyrate unit of monensin-A, an observation which can be rationalised if beta-aminoisobutyrate is converted to methacrylyl-CoA and then reduced to isobutyryl-CoA prior to conversion to butyryl-Coa by the action of isobutyryl-CoA mutase. Feeding experiments with [I-13C]- and [13C-methyl]-methacrylates and [3-13C]-isobutyrate suggest that these metabolites partition similarly between the butyrate and propionate units of monensin-A consistent with the view that isobutyryl-CoA and methacrylyl-CoA have a close metabolic relationship.