Associations between sleep complaints, suicidal ideation and depressive symptoms among adolescents and young adults in Greece

Depression prevalence increases significantly during adolescence/early adulthood. Depression in youth may present suicidal ideation, while suicide represents the leading cause of death in this age group. Moreover, adolescents/young adults frequently report sleep complaints that may partially be due to depressive symptoms. Studies on the associations between depression, sleep complaints and suicidality in this age group are limited. We aimed to examine associations between depressive symptoms, sleep complaints and suicidal ideation in a large (n = 2771), representative sample of adolescents (age: 15-17 years, n = 512) and young adults (age: 18-24 years, n = 2259) from the general population in Greece. A telephone structured questionnaire was administered. Depressive symptoms were assessed using the modified Patient Health-7 questionnaire score, while presence of suicidal ideation and sleep complaints were assessed using the ninth and third question of Patient Health-9 questionnaire, respectively. Mediation logistic regression analysis revealed significant direct paths from depressive symptoms to sleep complaints (odds ratio [OR] 1.22, 95% confidence interval [CI] 1.19-1.24; OR 1.21, 95% CI 1.18-1.24) and suicidal ideation (OR 1.18, 95% CI 1.14-1.22; OR 1.18, 95% CI 1.14-1.22), as well as sleep complaints and suicidal ideation (OR 1.82, 95% CI 1.32-2.50; OR 1.91, 95% CI 1.33-2.76) in the total group and in young adults, respectively, but not among adolescents. Moreover, we detected a significant indirect effect of depressive symptoms on suicidal ideation mediated by sleep complaints (18.8%) in young adults. These findings support the hypothesis that treatment of sleep disturbances among youth with depression may independently further reduce suicidal risk.

Driving Behaviour in Depressed Patients vs Healthy Controls

Introduction

Depression is characterized by mental, emotional and executive dysfunction, and it may have an impact on driving behaviour. The aim of the study was to evaluate driving performance in depression.

Methods

Participants (39 depressed patients vs 30 controls) completed questionnaires and scales on demographics, driving experience and habits, mental and physical health. They also completed two specific questionnaires on driving behaviour and attitude: the Driver Behaviour Questionnaire (DBQ) with three sub-scales (driving errors, traffic violations and attention lapses) and the Driver Stress Inventory (DSI) which assesses drivers' vulnerability to stress reactions while driving and consists of five sub-scales (aggression, dislike of driving, hazard monitoring, thrill seeking and proneness to fatigue).

Results

All driving sub-scales did not differ between cases and controls. For both the total population of participants and for depressed patients separately aggression and hazard monitoring (HM) were found to be positively correlated to fatigue severity scale total score (FSS), HM was correlated with male sex, and proneness to fatigue (PF) was negatively correlated with the total score of STOP-BANG, a questionnaire for probable sleep apnea. Only among depressed patients there was a positive correlation of PF with the total score of Athens Insomnia Scale (AIS), of traffic violations with AIS and body mass index, and of both dislike of driving and HM with the anxiety sub-scale of the Hospital Anxiety and Depression Scale. Only when all subjects were considered together, age was negatively correlated to thrill seeking and traffic violations.

Conclusions

While there are no significant differences between depressed patients and controls, there are parameters which influence driving behaviour and attitude similarly for both groups (especially fatigue and sex) and specific parameters only for depressed patients (anxiety, insomnia symptoms and BMI).

Key messages

Driving behaviour and attitude of depressed patients and healthy controls are influenced by specific parameters. Depression per se and its consequences, such as sleep disorders and anxiety, affect driving performance and attitude.

1120 Inverse U-Curve Association Between Sleep Duration and Cognitive Performance Among Patients with Dementia: Findings From the Cretan Aging Cohort

Introduction

Previous research reports an inverse U-curve association between subjective sleep duration and cognition in elderly, while findings on objective sleep duration are inconsistent. Only one study found weak association between objective short sleep duration and cognition, mainly driven by demented elders. Our aim was to examine the non-linear associations between objective sleep duration and cognitive performance among community-dwelling patients with dementia.

Methods

A sub-sample of 46 patients with mild-to-moderate dementia(AD) [mean age: 80.3 (SD=5.6) years, 40% males] and 85 cognitively intact controls(NI) [mean age: 73.0 (SD=7.4) years, 37% males], were recruited from a large, population-based cohort [Cretan Aging Cohort] in the island of Crete, Greece of 3,140 older adults (≥60yrs). All participants underwent medical history/physical examination, extensive neuropsychiatric and neuropsychological evaluation, and 3-day 24-h actigraphy. Comparisons between AD and NI participants on sleep parameters and neuropsychological performance were made using ANOVA controlling for demographics. Associations between 24-TST, and age- and education-adjusted cognitive scores and Independent Activity of Daily Living Scale (IADL) scores were assessed using hierarchical, non-linear, regression models, controlling for confounders.

Results

Dementia patients had significantly longer 24-h total sleep time (24h-TST) (491.2±107.1 min vs. 444.6±88.5 min, respectively, p=0.027), as well as lower cognitive/IADL sores as compared to the NI group. Significant associations between objective sleep and various cognitive /IADL scores were found only among patients with dementia. Specifically, we found a negative curvilinear association between 24-h TST and IADL, episodic memory indices (AVLT Retention, autobiographic memory) and visuomotor coordination speed (Trail Making Test, Part A).

Conclusion

Our study showed an inverse U-curve association between objective sleep duration and daily function, memory, and executive function in patients with dementia. Possibly, sleep loss may lead to cognitive impairment, whereas, prolonged sleep may be an indicator of worse cognitive performance among patients with dementia.

Support

National Strategic Reference Framework (ESPA) 2007-2013, Program: THALES, University of Crete, title: “A multi-disciplinary network for the study of Alzheimer’s Disease” (Grant: MIS 377299).

0585 C-Reactive Protein Improves the Ability to Detect Cardiometabolic Risk in Mild-to-Moderate Sleep Apnea

Introduction

Mild-to-moderate obstructive sleep apnea (OSA) affects 15-40% of the adult general population. However, it remains unclear when and how best to treat mild-to-moderate OSA. It has been shown that mild-to-moderate OSA in general random samples is associated with incident hypertension. The aim of this study was to compare the relative utility of apnea/hypopnea index (AHI) versus a biomarker of inflammation, C-reactive protein (CRP), in identifying the presence and severity of hypertension and insulin resistance (IR).

Methods

A clinical sample of 148 adults (53.79±12.45) with mild-to-moderate OSA (AHI between 5 and 29 events per hour) underwent 8-hour polysomnography, a clinical history and physical examination, including measures of blood pressure, body mass index (BMI), fasting blood glucose, insulin and CRP plasma levels. Hypertension was defined by previous diagnosis, past or present treatment, or blood pressure ≥140/90. IR was defined by homeostatic model assessment. Individuals with diabetes and/or on diabetes medication were excluded from analyses with IR. All analyses were conducted controlling for age, gender and BMI.

Results

CRP levels (OR=2.62, 95% CI=1.35-5.04, p=0.004), age (OR=1.75, 95% CI=1.11-2.75, p=0.016), and BMI (OR=2.74, 95% CI=1.20-6.26, p=0.017) were independently associated with greater odds for hypertension, whereas AHI (OR=1.33, 95% CI=0.61-2.92, p=0.477) was not. Additionally, CRP levels (β=0.21; p=0.04) and BMI (β=0.24; p=0.02) were independently associated with higher IR, while AHI (β=-0.03; p=0.75) was not. There was a trend for this association to be stronger in non-obese patients.

Conclusion

These preliminary findings suggest that including a measure of inflammation improves the ability for clinicians to detect cases of mild-to-moderate OSA with true cardiometabolic risk. CRP may be a simple, easy-to-use biomarker that can improve prognosis assessment and clarify which treatment option is best for patients with mild-to-moderate OSA.

Support

Department of Psychiatry, Penn State College of Medicine

1035 Sleep Duration and Metabolic Syndrome: An Updated Systematic Review and Meta-Analysis

Introduction

To systematically examine the association between sleep duration and metabolic syndrome (Mets) risk in cross-sectional and prospective cohort studies.

Methods

Data were collected from 36 cross-sectional and 9 longitudinal studies with a total of 164799 MetS subjects and 430895 controls. Odds ratios (ORs) for MetS in cross-sectional studies and risk ratios (RRs) for incident MetS were calculated through meta-analyses of adjusted data from individual studies. Subgroup analyses were performed to investigate the association between MetS and the duration of short-and-long sleep.

Results

Short sleep duration was significantly associated with increased prevalent MetS (OR= 1.11, 95% CI =1.05-1.18) and incident MetS (RR= 1.28, 95% CI =1.07-1.53,) in cross-sectional and longitudinal studies, respectively. Furthermore, long sleep duration was significantly associated with increased prevalent MetS in cross-sectional studies (OR= 1.14, 95% CI =1.05-1.23), rather than incident MetS (RR= 1.16, 95% CI =0.95-1.41) in longitudinal studies. Interestingly, the association between long sleep and prevalent MetS was found in sleep duration defined by 24-hour sleep (including naps) rather than nighttime sleep. In cross-sectional studies, pooled odds for MetS were 1.36 (95% CI=1.04-1.78, I2=83.3%) in ≤ 5 hours, 1.09 (95% CI=1.02-1.16, I2=67.8%) in ≤6 hours, 1.01 (95% CI=0.93-1.10, I2=24.9%) in <7 hours, 1.11 (95% CI=1.02-1.21, I2=67.0%) in ≥9 hours and 1.31 (95% CI=1.22-1.40, I2=0%) in ≥10 hours, respectively. The association of short sleep and MetS was stronger in young and middle age adults, but lost in adults age >60 years.

Conclusion

Our findings suggest 1) a “U-shape” relationship between sleep duration and MetS in cross-sectional studies and 2) association between short sleep duration, but not long sleep duration with incident MetS. Future studies should shed light on the underlying mechanisms related to the association between sleep duration and MetS and examine if normalizing sleep duration reduces MetS risk in the general population.

Support

This study was supported by National Natural Science Foundation of China (No. 81600068 & 81970087), the Young Elite Scientists Sponsorship Program by CAST (No. YESS20160072), Medical Science Foundation of Guangdong Provence (A2018296) and Grant for Key Disciplinary Project of Clinical Medicine under the Guangdong High-level University Development Program.

0506 Short and Long-Term Effects of Trazodone vs. Cognitive-Behavioral Treatment on EEG Power During NREM Sleep in Chronic Insomnia

Introduction

Both trazodone and cognitive-behavioral treatment of insomnia (CBT-I) are widely used to treat patients with chronic insomnia. Animal studies have shown that trazodone increases slow wave sleep (i.e., increased EEG delta power). However, no study to date has compared the long term effects of trazodone vs. CBT-I on spectral EEG activity during sleep in humans.

Methods

We addressed this question in a sample of 19 middle-aged men and women who received either trazodone (n=8) or CBT-I (n=11) treatment for 9 months. We examined delta (0.39-3.91 Hz), theta (4.30-7.81 Hz), alpha (8.20-11.72 Hz), sigma (12.11-14.84 Hz), beta (15.23-35.16 Hz) and gamma (35.55-49.61 Hz) relative power during NREM sleep after 3-month and 9-month of treatment.

Results

Compared to CBT-I, trazodone significantly increased relative delta power (p=0.05) and decreased relative sigma (p=0.004) and beta (p=0.05) power during NREM sleep across 9-month treatment. Furthermore, compared to CBT-I, trazodone significantly increased relative delta power (3-month: Δ2.00 ± 3.27 vs. Δ-2.63 ± 5.88, p=0.006, Cohen’s d=0.93; 9-month: Δ2.63 ± 4.11 vs. Δ-1.10 ± 3.93, p=0.006, Cohen’s d=0.93), while decreased relative sigma power (3-month: Δ-1.55 ± 1.75 vs. Δ0.90 ± 1.82, p=0.009, Cohen’s d=1.37; 9-month: Δ-1.33 ± 1.95 vs. Δ1.05 ± 1.79, p=0.014, Cohen’s d=1.28) during NREM sleep in 3-month and 9-month, respectively. Relative beta power (3-month: Δ-0.85 ± 0.60 vs. Δ0.35 ± 1.14, p=0.016, Cohen’s d=1.03;) was significantly decreased in 3-month treatment in trazodone group compared to CBT-I. Moreover, across 9-month treatment, relative sigma (p=0.040, ω p2 = 0.29) and beta (p=0.021, ω p2 = 0.12) power during NREM sleep were significantly decreased within trazodone group, while relative sigma power (p=0.096, ω p2 = 0.230) increased within CBT-I group.

Conclusion

Our findings suggest that trazodone, but not CBT-I, even after 9-month of use increases slow wave sleep and decreases high-frequency EEG power during NREM sleep. This effect may explain the long-term usefulness of trazodone in chronic insomnia patients with physiologic hyperarousal i.e., activation of the stress system. Further studies should examine this effect in large samples of insomnia.

Support

NIH C06 RR016499, UL1 TR 000127

0458 Smoking and Caffeine Consumption Differ Between Insomnia Phenotypes Based on Objective Sleep Duration

Introduction

The insomnia with short sleep phenotype (ISS), in contrast to the normal sleep phenotype (INS), is characterized by physiological hyperarousal including activation of the stress system and cardiometabolic morbidity. The aim of this study was to assess whether these two insomnia phenotypes differ in terms of the use of two common stimulants (i.e., caffeine and nicotine).

Methods

Data from the Penn State Adult Cohort (N=1741) was used in this study (52.2% women, 48.8±13.6 years). A 1-night, 8-hour, polysomnography (PSG) was used to classify subjects into normal (≥6h) and short (<6h) sleep duration groups. Self-reported sleep difficulty was defined based on three levels of severity as normal sleep (n=1022), poor sleep (n=520) and insomnia (n=199). Self-reported heavy caffeine use was defined as ≥3 cups daily and heavy smoking as ≥20 cigarettes daily. Multinomial logistic regression analyses were conducted adjusting for covariates such as age, gender, and race.

Results

Compared to normal sleepers, ISS (OR=0.55, 95% CI=0.31-0.97, p=0.04), but not INS (OR=0.92, 95% CI=0.52-1.64, p=0.77), was associated with significantly less heavy caffeine use. In contrast, INS (OR=2.20, 95% CI=1.10-4.40, p=0.03), but not ISS (OR=0.95, 95% CI=0.41-2.17, p=0.90), was associated with significantly more heavy smoking.

Conclusion

These results indicate that the use of common stimulants (i.e., smoking cigarettes and drinking caffeine) is higher in the INS phenotype than the ISS phenotype. Individuals with the ISS phenotype may be using less caffeine and tobacco to avoid further stimulation of the already hyperaroused physiologic system, which may result in worsening of their insomnia. In the INS phenotype, changes in health behaviors should be an important part of a multidimensional approach to treatment.

Support

American Heart Association (14SDG19830018), National Institutes of Health (R01HL51931, R01HL40916)

1130 Insomnia Short Sleep Phenotype is Associated With Frailty in Patients With Mild Cognitive Impairment (MCI)

Introduction

Insomnia short sleep phenotype is associated with cardiometabolic morbidity and mortality and neuropsychological impairment. In elderly untreated insomnia is associated with worse cognitive performance. The goal of the study was to examine the association between insomnia, objective sleep duration and physical and mental health in elderly patients with Mild Cognitive Impairment (MCI).

Methods

A sub-sample of 105 patients with MCI (mean age: 75.9 years, males 36%) were recruited from a large population-based cohort (Cretan Aging Cohort) in the island of Crete, Greece of 3,140 elders (≥ 60yrs). All participants underwent a complete medical history/ physical examination, extensive neuropsychiatric and neuropsychological evaluation and 3-day 24hr actigraphy. Insomnia was defined based on a question “do you have insomnia for more than a year”. Frailty was assessed with the Simple “Frail” Questionnaire Screening Tool. Comparisons between patients with insomnia and without insomnia were made using ANOVA controlling for age, gender and BMI.

Results

MCI patients with insomnia (n=23) compared to those without insomnia (n=82), had significantly shorter objective total sleep time (TST: 377 vs. 410 min, p=0.05) and significantly higher scores on the Geriatric Depression Scale and the Hospital Anxiety Scale (both p <0.001). Furthermore, total frailty score, as well as scores in individual items, were significantly lower in MCI patients with insomnia (p<0.01). This association remained significant after controlling for demographics, depression and anxiety. Finally, there was a statistical trend of association between insomnia and hypertension (p= 0.1).

Conclusion

In MCI patients, insomnia is associated with objective short sleep duration, and frailty. Improving insomnia and lengthening sleep duration may decrease frailty, a major problem associated with morbidity, disability and mortality in elders with cognitive decline.

Support

National Strategic Reference Framework (ESPA) 2007-2013, Program: THALES, University of Crete, title: “A multi-disciplinary network for the study of Alzheimer’s Disease” (Grant: MIS 377299).

Differential effects of earthquakes on patients with bipolar disorder versus schizophrenia: Findings from Crete, Greece, 2008-2010

Electromagnetic radiation influences in many ways humans and animals, while earthquakes are known to be related with electromagnetic phenomena. We recently showed that large earthquakes reduced admissions of psychiatric patients, whereas small earthquakes were associated with increased number of admissions. Our aim was to examine the effect of seismic-related electromagnetic activity on two chronic and severe psychiatric disorders varying in terms of etiology and treatment, i.e. bipolar disorder and schizophrenia. Retrospective data concerning monthly admission rates of patients diagnosed with schizophrenia or bipolar disorder in the Psychiatric Unit of the University Hospital of Heraklion, Crete, Greece between 2008 and 2010 were analyzed in relation to the number of earthquakes with small (≥2) or larger magnitude in the Crete region in Greece. Results showed a marked reduction of acute admissions during a storm of large earthquakes, which was greater in patients with bipolar disorder (91.2%) than schizophrenia patients (52.4%). In addition there was a significant increase of admissions during a period of frequent small earthquakes, primarily among patients with bipolar disorder. The results suggest that electrostatic fields that accompany large earthquakes may have a protective effect on psychiatric disorders, particularly on bipolar disorder. These findings are consistent with the ameliorating effect of electromagnetic fields used in Electroconvulsive therapy (ECT) and Transcranial Magnetic Stimulation (TMS) in patients with bipolar disorder. Future studies focusing on the underlying mechanisms may lead to more specific treatments of psychiatric disorders.

Abstract WMP104: Complement System is Acutely Activated in Humans After Intracerebral Hemorrhage

Introduction: Intracerebral hemorrhage (ICH) generates a complex local and systemic inflammatory response, but prior studies have neglected the role of the complement system. While animal models of ICH have suggested complement is a key regulator of inflammation, human data are lacking. We investigated whether the complement system was activated in ICH patients.

Hypothesis: We hypothesized complement system activation product levels would be acutely elevated in ICH patients compared to matched controls. We also examined the association of these complement fragment levels with established ICH severity markers and perihematomal edema (PHE) growth rates.

Methods: We identified 25 ICH patients whose blood was collected within 5 days post stroke at the University of Maryland Medical Center from June 2016 to September 2017 as part of the Recovery After Cerebral Hemorrhage (REACH) and Genetic and Environmental Risk Factors for Hemorrhagic Stroke (GERFHS) studies. C3a, C5a, and sC5b-9 levels were measured via ELISA (Quidel, San Diego, CA) in patients and healthy controls matched for age, sex, and race. Six patients were excluded from PHE growth measurement for lack of available follow-up CT or MRI scans. Hematoma and PHE volumes were measured on the initial CT scan and the follow-up CT scan (or MRI scan if CT not done) closest to 72 hours post stroke via a semi-automated method.

Results: Mean C3a (82.4 versus 49.2 ng/mL, p = 0.01), C5a (19.2 versus 9.1 ng/mL, p = 0.00005), and sC5b-9 (3000 versus 246 ng/mL, p = 0.00006) levels were elevated in ICH patients relative to matched controls. In secondary analyses, C5a level was correlated with presence of intraventricular hemorrhage (correlation coefficient 0.51, p = 0.03) and modified Graeb score (correlation coefficient 0.50, p = 0.03). Complement fragment levels were not correlated with PHE growth rates, age, ICH size, ICH location, or presence of at least 2 systemic inflammatory response syndrome (SIRS) criteria.

Conclusions: Activated complement fragments C3a, C5a, and sC5b-9 are significantly (several-fold) elevated in ICH patients independently of age, ICH size, and ICH location. Considering complement’s role in initiating and augmenting inflammation, it represents a potential novel therapeutic target.

Factors associated with repeat diagnosis of syphilis in genitourinary medicine (GUM) clinic attendees in the North East of England, 2002-2014

This study aimed to identify factors associated with repeat syphilis infection in North East England, in order to inform local prevention and control opportunities. We undertook a case-case study comparing individuals diagnosed with single or multiple episodes of syphilis infection within genitourinary medicine (GUM) clinics in NE England (12 clinics serving a population of 2.5 million). Study cases were verified as having had true re-infection by a GUM clinician (using serological and/or clinical parameters) and control cases (3 per case) frequency matched to cases by age and year of presentation. The odds of exposure to sexual behavioural and clinical factors were compared for cases and control cases using stepwise multivariable logistic regression. We included 66 cases and 235 control cases. The majority of cases (62/66) and control cases (165/235) were men who had sex with men (MSM). Data were missing for 0-64% of cases across different variables. Following multivariable analysis HIV seropositivity (OR 23.3, 95% CI 4.32-125.9), failure to attend follow-up (OR 4.63, 95% CI 1.11-19.31), stage of infection and deprivation were associated with re-infection ( p < 0.001). In this study, HIV seropositivity and failure to attend follow-up were associated with re-infection with syphilis. Actions targeted at these groups may help to reduce ongoing transmission.

IVIg attenuates complement and improves spinal cord injury outcomes in mice

Objective

Traumatic spinal cord injury (SCI) elicits immediate neural cell death, axonal damage, and disruption of the blood–spinal cord barrier, allowing circulating immune cells and blood proteins into the spinal parenchyma. The inflammatory response to SCI involves robust complement system activation, which contributes to secondary injury and impairs neurological recovery. This study aimed to determine whether intravenous immunoglobulin (IVIg), an FDA‐approved treatment for inflammatory conditions, can scavenge complement activation products and improve recovery from contusive SCI.

Methods

We used functional testing, noninvasive imaging, and detailed postmortem analysis to assess whether IVIg therapy is effective in a mouse model of severe contusive SCI.

Results

IVIg therapy at doses of 0.5–2 g/kg improved the functional and histopathological outcomes from SCI, conferring protection against lesion enlargement, demyelination, central canal dilation, and axonal degeneration. The benefits of IVIg were detectable through noninvasive diffusion tensor imaging (DTI), with IVIg treatment counteracting the progressive SCI‐induced increase in radial diffusivity (RD) in white matter. Diffusion indices significantly correlated with the functional performance of individual mice and accurately predicted the degree of myelin preservation. Further experiments revealed that IVIg therapy reduced the presence of complement activation products and phagocytically active macrophages at the lesion site, providing insight as to its mechanisms of action.

Interpretation

Our findings highlight the potential of using IVIg as an immunomodulatory treatment for SCI, and the value of DTI to assess tissue damage and screen for the efficacy of candidate intervention strategies in preclinical models of SCI, both quantitatively and noninvasively.

7th International Immunoglobulin Conference: Mechanisms of action

Although intravenous immunoglobulin (IVIg) is widely used for replacement therapy in immunodeficiencies and to treat autoimmune and inflammatory diseases, its mechanisms of action are not fully understood. Examination of immunoglobulin (Ig) receptors, including the Fc-gamma receptors (FCγRs) and the neonatal Fc receptor, have revealed genetic variations that are linked to autoimmune diseases and to the efficacy of IVIg treatment. However, the beneficial effect of IVIg encompasses multiple mechanisms of action. One of these is scavenging of activated complement fragments, such as C3a, C5a, C3b and C4b, by infused Ig molecules. This interaction prevents binding of complement fragments to their receptors on target cells, thus attenuating the immune damage. Additionally, anti-inflammatory effects may be facilitated by IgA via specific receptors and/or complement scavenging. Glycosylation of both the Fc- and Fab-fragments has also been implicated in the anti-inflammatory action of IVIg. Although there is evidence to support a role for sialylated IgG glycovariants in mediating the effect of IVIg, evidence from animal models of inflammatory disease suggest that sialylation may not be a critical factor. However, an increase in IgG glycosylation has been observed following IVIg treatment in Guillain-Barré syndrome patients, and this has been associated with improved clinical outcomes.

7th International Immunoglobulin Conference: Mechanisms of action

The mechanism of action by which therapeutic administration of intravenous immunoglobulin (IVIg) is able to provide a beneficial effect in autoimmune and inflammatory diseases is not yet fully understood, but current research is providing some answers. Signalling via receptors that interact with immunoglobulin (Ig) is crucial, and genetic polymorphisms of the Fc receptors have clear links to disease and also appear to influence the outcome of IVIg treatment. Glycosylation of the IgG, Fc- or Fab-fragments has a role in enhancing or blocking the pro- and anti-inflammatory effector functions. In addition, and independently of Fc receptors and glycosylation, Fc fragment and the constant domain of the Fab fragment contain binding sites for activated complement fragments that mediate complement-scavenging based immunomodulation. Although IgG Fc sialylation may not be critical for IVIg activity, research in some diseases suggests that it is associated with improved clinical outcomes. Therefore, further investigation of how IgG and IgA receptor expression and regulation affects the outcome of IVIg treatment may further clarify the mechanisms behind IVIg, and provide valuable guidance for future treatment paradigms.

Intravenous immunoglobulin (IVIg) provides protection against endothelial cell dysfunction and death in ischemic stroke

BACKGROUND

The brain endothelium is a key component of the blood brain barrier which is compromised following ischemia, allowing infiltration of damaging immune cells and other inflammatory molecules into the brain. Intravenous immunoglobulin (IVIg) is known to reduce infarct size in a mouse model of experimental stroke.

FINDINGS

Flow cytometry analysis showed that the protective effect of IVIg in ischemia and reperfusion injury in vivo is associated with reduced leukocyte infiltration, suggesting an involvement of the endothelium. In an in vitro model of ischemia, permeability analysis of the mouse brain endothelial cell line bEnd.3 revealed that IVIg prevented the loss of permeability caused by oxygen and glucose deprivation (OGD). In addition, western blot analysis of these brain endothelial cells showed that IVIg prevented the down-regulation of tight junction proteins claudin 5 and occludin and the decline in anti-apoptotic proteins Bcl-2 and Bcl-XL caused by OGD.

CONCLUSION

IVIg protects endothelial cells from ischemic insult. These studies support the use of IVIg as a pharmacological intervention for stroke therapy.

Ultrafast Optical Properties of Dense Electron Gas in Silicon Nanostructures

We investigate the ultrafast dynamics of carriers in a silicon nanostructure by performing spectrally resolved femtosecond spectroscopy measurements with a supercontinuum probe. The nanostructure consists of a 158-nm-thick crystalline Si layer on top of which a SiO₂ passivation layer leads to a very high quality of the Si surface. In addition, a dielectric function approach, including contributions from a Drude part and interband transitions, combined with the Transition Matrix Approximation is used to model the photogenerated carrier dynamics. The spectrotemporal reflectivity reveals two mechanisms. First, an electron-hole plasma is created by the pump pulse and lasts for a few picoseconds. Importantly, its spectral signature is either a positive or a negative change of reflectivity, depending on the probe wavelength. This is complementary to the already reported results obtained with degenerate frequency measurements. The second mechanism is a thermal diffusion of carriers which occurs during several hundreds of picoseconds. The overall dynamics at short and long delays in the whole visible spectrum is well explained with our model which shows that the main contribution to the reflectivity dynamics is due to the Drude dielectric function. The observation of this predominance of free carriers requires both a long lived high density of carriers as well as a little influence of surface scattering as provided by our thin crystalline Si layer with passivated Si/SiO₂ interface.

Intravenous immunoglobulin protects neurons against amyloid beta-peptide toxicity and ischemic stroke by attenuating multiple cell death pathways

Intravenous immunoglobulin (IVIg) preparations obtained by fractionating blood plasma, are increasingly being used increasingly as an effective therapeutic agent in treatment of several inflammatory diseases. Its use as a potential therapeutic agent for treatment of stroke and Alzheimer's disease has been proposed, but little is known about the neuroprotective mechanisms of IVIg. In this study, we investigated the effect of IVIg on downstream signaling pathways that are involved in neuronal cell death in experimental models of stroke and Alzheimer's disease. Treatment of cultured neurons with IVIg reduced simulated ischemia- and amyloid βpeptide (Aβ)-induced caspase 3 cleavage, and phosphorylation of the cell death-associated kinases p38MAPK, c-Jun NH2 -terminal kinase and p65, in vitro. Additionally, Aβ-induced accumulation of the lipid peroxidation product 4-hydroxynonenal was attenuated in neurons treated with IVIg. IVIg treatment also up-regulated the anti-apoptotic protein, Bcl2 in cortical neurons under ischemia-like conditions and exposure to Aβ. Treatment of mice with IVIg reduced neuronal cell loss, apoptosis and infarct size, and improved functional outcome in a model of focal ischemic stroke. Together, these results indicate that IVIg acts directly on neurons to protect them against ischemic stroke and Aβ-induced neuronal apoptosis by inhibiting cell death pathways and by elevating levels of the anti-apoptotic protein Bcl2.

Intravenous immunoglobulins--understanding properties and mechanisms

High-dose intravenous immunoglobulin (IVIg) preparations are used currently for the treatment of autoimmune or inflammatory diseases. Despite numerous studies demonstrating efficacy, the precise mode of action of IVIg remains unclear. Paradoxically, IgG can exert both pro- and anti-inflammatory activities, depending on its concentration. The proinflammatory activity of low-dose IVIg requires complement activation or binding of the Fc fragment of IgG to IgG-specific receptors (FcgammaR) on innate immune effector cells. In contrast, when administered in high concentrations, IVIg has anti-inflammatory properties. How this anti-inflammatory effect is mediated has not yet been elucidated fully, and several mutually non-exclusive mechanisms have been proposed. This paper represents the proceedings of a session entitled 'IVIg--Understanding properties and mechanisms' at the 6th International Immunoglobulin Symposium that was held in Interlaken on 26-28 March 2009. The presentations addressed how IgG may affect the cellular compartment, evidence for IVIg-mediated scavenging of complement fragments, the role of the dimeric fraction of IVIg, the anti-inflammatory properties of the minor fraction of sialylated IgG molecules, and the genetic organization and variation in FcgammaRs. These findings demonstrate the considerable progress that has been made in understanding the mechanisms of action of IVIgs, and may influence future perspectives in the field of Ig therapy.