POS0761 TIME-DEPENDENT ANALYSES OF CLINICAL MANIFESTATIONS OF SYSTEMIC LUPUS ERYTHEMATOSUS IDENTIFY PATIENTS AT HIGH RISK OF INCIDENT PROTEINURIA

Background

Nephritis (LN) in systemic lupus erythematosus (SLE) is still a major determinant of poor prognosis[1].

The vast majority of LN occurs in proximity to the SLE diagnosis[2]. Identification of individuals at high risk, especially early onset SLE, is therefore warranted. Inclusion of risk factors prior to the SLE diagnosis may thus be of importance to enable sufficient risk factor profiling. SLE-patients seem to cluster according to clinical and serological phenotypes suggesting distinct disease trajectories[3-5].

Objectives

To determine if incident proteinuria associated with the debut age of non-renal SLE characteristics.

Methods

Data of SLE patients from six Danish centers were obtained from the Danbio-database from 2017 – 2020. The occurrence and timing of proteinuria was compared with first time onset of any non-renal manifestations as defined by the 1997 American College of Rheumatology Classification Criteria. Cox-regression models were used to identify risk factors for incident proteinuria. Time from first occurring non-renal manifestation to incident proteinuria or censoring defined time at risk. Covariates were eliminated if p >0.01 in a ‘backwards’ manner. After the model reduction process p-values <0.05 were considered statistically significant.

Results

586 SLE patients, mainly white (94%) women (88%), mean age at inclusion of 34.6 years (standard deviation, SD = 0.6 years) and observed for a mean of 14.9 years (SD =0.5 years), were recruited. The cumulative prevalence of proteinuria was 40%. Male gender hazard ratio, HR = 1.35 (range 0.77-2.35), p=0.009, lymphopenia HR = 1.77 (range 1.24-2.52), p=0.005 were associated with incident proteinuria. In contrast, patients with discoid rash had lower risk of incident proteinuria HR 0.42 (range 0.21-0.83), p=0.01. Male patients with lymphopenia had the highest risk of proteinuria with a one-, 5- and 10-year risk of proteinuria ranging from 9-27%, 34-75% and 51-89 %, depending on the age at presentation (debut at 20, 30, 40 or 50 years). The corresponding risk-profiles for women with lymphopenia were 3-9%, 8-34% and 12-58%, respectively, as illustrated in Figure 1.

Conclusion

The occurrences of lymphopenia and discoid rash were oppositely associated with risk of incident proteinuria and the risk effects varied according to gender and patient age at onset of these manifestations. Thus, the risk of proteinuria may not be constant but could vary according to presentation of non-renal manifestations that may call for a differentiated clinical follow-up. Based on these findings, we suggest that the debut age of known prognostic factors, even prior to the SLE diagnosis should be considered when designing prognostic statistical models.

References

[1]Faurschou, M., et al., Prognostic factors in lupus nephritis: diagnostic and therapeutic delay increases the risk of terminal renal failure. J Rheumatol, 2006. 33(8): p. 1563-9.

[2]Hanly, J.G., et al., The frequency and outcome of lupus nephritis: results from an international inception cohort study. Rheumatology (Oxford), 2016. 55(2): p. 252-62.

[3]Diaz-Gallo, L.M., et al., Four Systemic Lupus Erythematosus Subgroups, Defined by Autoantibodies Status, Differ Regarding HLA-DRB1 Genotype Associations and Immunological and Clinical Manifestations. ACR Open Rheumatol, 2022. 4(1): p. 27-39.

[4]Jacobsen, S., et al., A multicentre study of 513 Danish patients with systemic lupus erythematosus. II. Disease mortality and clinical factors of prognostic value. Clin Rheumatol, 1998. 17(6): p. 478-84.

[5]Leffers, H.C.B., et al., Smoking associates with distinct clinical phenotypes in patients with systemic lupus erythematosus: a nationwide Danish cross-sectional study. Lupus Sci Med, 2021. 8(1).

Disclosure of Interests

Martin Andersen Employee of: Novo Nordisk A/S: 2010-2014, Anders Stockmarr: None declared, Henrik Leffers: None declared, Anne Troldborg: None declared, Anne Voss: None declared, Salome Kristensen: None declared, Bent Deleuran: None declared, Lene Dreyer Speakers bureau: Speakers bureau: Eli Lilly, Galderma and Janssen, Grant/research support from: Grant from BMS outside the present work, Laura Johnsen: None declared, Ada Colic: None declared, Søren Jacobsen: None declared

Three-dimensional Ultrasound Volume and Conventional Ultrasound Diameter Changes are Equally Good Markers of Endoleak in Follow-up after Endovascular Aneurysm Repair

INTRODUCTION

The main disadvantages of computed tomography angiography in follow-up after endovascular aneurysm repair are the risks of contrast-induced renal impairment and radiation-induced cancer. Three-dimensional ultrasound is a new technique for volume estimation of the aneurysm sac. Some studies have reported promising results. The aim of this study was to evaluate the accuracy and precision of three-dimensional ultrasound aneurysm sac-volume estimates, and to explore whether volume and/or diameter changes on ultrasound can be used as markers of endoleak.

METHODS

A single-center diagnostic accuracy study was performed. 92 Patients planned for endovascular aneurysm repair were prospectively and consecutively enrolled (2013-2016). Aneurysm sac diameter and volume were measured using computed tomography angiography, conventional ultrasound, and three-dimensional ultrasound preoperatively and 1, 6, 12, and 24 months postoperatively. Three-dimensional ultrasound was performed with a commercially available electromechanical transducer. Patients with endoleak were observed 5 years after endovascular aneurysm repair.

RESULTS

79 men and 13 women were included. Mean age was 74 years (57-92). Median follow-up was 24 months. Endoleak cases were observed for up to 55 months. Diameter measurements on conventional ultrasound correlated well with CT diameters (r = 0.9, P < 0.05, n = 347), and Bland-Altman analyses showed an upper limit of agreement of +0.5 cm and a lower limit of agreement of -0.8 cm. The mean difference was -0.13 cm ± 0.36 cm. Three-dimensional ultrasound volumes had a correlation with computed tomography angiography diameters of r = 0.8 (P < 0.05, n = 347) and with three-dimensional computed tomography volumes of r = 0.8 (P < 0.05, n = 155). Receiver operating characteristic analyses showed that the diameter and volume changes which led to reintervention were most accurate at 24-month follow-up, with area-under-the-curve percentage changes of 0.98 (two-dimensional ultrasound), 0.97 (three-dimensional ultrasound), and 0.97 (two-dimensional computed tomography).

DISCUSSION

Both diameter and volume changes can be used as markers for endoleak with excellent areas under the curve on receiver operating characteristic analyses. However, three-dimensional ultrasound volumes did not add any further diagnostic information. Conventional 2D diameter measurements were as accurate as volume changes as markers of endoleak.

CONCLUSION

Type II endoleaks can safely be followed up using a simple diameter measurement on conventional ultrasound.

Prediction of radiation-induced mucositis of H&N cancer patients based on a large patient cohort

PURPOSE/OBJECTIVE

Radiation-induced mucositis is a severe acute side effect, which can jeopardize treatment compliance and cause weight loss during treatment. The study aimed to develop robust models to predict the risk of severe mucositis.

MATERIALS/METHODS

Mucosal toxicity scores were prospectively recorded for 802 consecutive Head and Neck (H&N) cancer patients and dichotomised into non-severe event (grade 0-2) and severe event (grade 3+) groups. Two different model approaches were utilised to evaluate the robustness of the models. These used LASSO and Best Subset selection combined with 10-fold cross-validation performed on two-thirds of the patient cohort using principal component analysis of DVHs. The remaining one-third of the patients were used for validation. Model performance was tested through calibration plot and model performance metrics.

RESULTS

The main predicted risk factors were treatment acceleration and the first two principal dose components, which reflect the mean dose and the balance between high and low doses to the oral cavity. For the LASSO model, gender and current smoker status were also included in the model. The AUC values of the two models on the validation cohort were 0.797 (95%CI: 0.741-0.857) and 0.808 (95%CI: 0.749-0.859), respectively. The two models predicted very similar risk values with an internal Pearson coefficient of 0.954, indicating their robustness.

CONCLUSIONS

Robust prediction models of the risk of severe mucositis have been developed based on information from the entire dose distribution for a large cohort of patients consisting of all patients treated H&N for within our institution over a five year period.

NTCP model validation method for DAHANCA patient selection of protons versus photons in head and neck cancer radiotherapy

Introduction: Prediction models using logistic regression may perform poorly in external patient cohorts. However, there is a need to standardize and validate models for clinical use. The purpose of this project was to describe a method for validation of external NTCP models used for patient selection in the randomized trial of protons versus photons in head and neck cancer radiotherapy, DAHANCA 35. Material and methods: Organs at risk of 588 patients treated primarily with IMRT in the randomized controlled DAHANCA19 trial were retrospectively contoured according to recent international recommendations. Dose metrics were extracted using MatLab and all clinical parameters were retrieved from the DAHANCA database. The model proposed by Christianen et al. to predict physician-rated dysphagia was validated through the closed testing, where change of the model intercept, slope and individual beta's were tested for significant prediction improvements. Results: Six months prevalence of dysphagia in the validation cohort was 33%. The closed testing procedure for physician-rated dysphagia showed that the Christianen et al. model needed an intercept refitting for the best match for the Danish patients. The intercept update increased the risk of dysphagia for the validation cohort by 7.9 ± 2.5% point. For the raw model performance, the Brier score (mean squared residual) was 0.467, which improved significantly with a new intercept to 0.415. Conclusions: The previously published Dutch dysphagia model needed an intercept update to match the Danish patient cohort. The implementation of a closed testing procedure on the current validation cohort allows quick and efficient validation of external NTCP models for patient selection in the future.

Relationship between patient and physician-rated xerostomia and dose distribution to the oral cavity and salivary glands for head and neck cancer patients after radiotherapy

Introduction: Xerostomia is a frequent complication after curative intended radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC). Assessment of xerostomia is commonly done by the physician. The aim of this study is to investigate the relation between patient and physician-rated xerostomia and to predict the degree of xerostomia from patients with self-reported xerostomia based on delivered doses to the oral cavity, parotid, and submandibular glands. Material and methods: During a 2-year period, consecutive HNSCC patients attending the follow-up clinic were included. All included patients had self-reported xerostomia, and completed the disease-specific EORTC QLQ-H&N35 questionnaire. The physician assessed the degree of xerostomia with the DAHANCA toxicity scale and was blinded for the EORTC score. Oral cavity, parotid, and submandibular glands (OAR) were delineated on the planning CT according to international guidelines. DVH were extracted from treatment plans. Logistic regression tested the relation between mean doses, patient characteristics, and xerostomia scores. Differences between DVH values and scoring of xerostomia were analyzed with a Kruskal-Wallis test. The relation between xerostomia and dose distributions was further investigated using principal component analysis (PCA). Results: In total, 109 patients were included in the study. A weak correlation was seen between patient and physician-rated toxicity (p = .001), however, in general patients reported more toxicity than physicians. For EORTC score ≥2, the multi-variable analysis was significant for doses to the oral cavity, tobacco status and use of xerogenic medication. Neither the DVH analysis nor the PCA found any clear distinction between xerostomia scores for EORTC or DAHANCA and investigated OARs. Conclusion: Patients tended to report higher scores of xerostomia than the physician. PCA indicated a complex relation between doses to the OAR and xerostomia scores, showing e.g., that reducing doses in one organ was on the expense of increased dose to another organ.

Fetal over- and undernutrition differentially program thyroid axis adaptability in adult sheep

OBJECTIVE

We aimed to test, whether fetal under- or overnutrition differentially program the thyroid axis with lasting effects on energy metabolism, and if early-life postnatal overnutrition modulates implications of prenatal programming.

DESIGN

Twin-pregnant sheep (n = 36) were either adequately (NORM), under- (LOW; 50% of NORM) or overnourished (HIGH; 150% of energy and 110% of protein requirements) in the last-trimester of gestation. From 3 days-of-age to 6 months-of-age, twin lambs received a conventional (CONV) or an obesogenic, high-carbohydrate high-fat (HCHF) diet. Subgroups were slaughtered at 6-months-of-age. Remaining lambs were fed a low-fat diet until 2½ years-of-age (adulthood).

METHODS

Serum hormone levels were determined at 6 months- and 2½ years-of-age. At 2½ years-of-age, feed intake capacity (intake over 4-h following 72-h fasting) was determined, and an intravenous thyroxine tolerance test (iTTT) was performed, including measurements of heart rate, rectal temperature and energy expenditure (EE).

RESULTS

In the iTTT, the LOW and nutritionally mismatched NORM:HCHF and HIGH:CONV sheep increased serum T₃, T₃:T₄ and T₃:TSH less than NORM:CONV, whereas TSH was decreased less in HIGH, NORM:HCHF and LOW:HCHF. Early postnatal exposure to the HCHF diet decreased basal adult EE in NORM and HIGH, but not LOW, and increased adult feed intake capacity in NORM and LOW, but not HIGH.Conclusions: The iTTT revealed a differential programming of central and peripheral HPT axis function in response to late fetal malnutrition and an early postnatal obesogenic diet, with long-term implications for adult HPT axis adaptability and associated consequences for adiposity risk.

Neuronal death in the dorsal root ganglion after sciatic nerve injury does not depend on sortilin

Injury to the sciatic nerve induces loss of sensory neurons in the affected dorsal root ganglia (DRGs). Previous studies have suggested the involvement of the neurotrophin receptors p75 neurotrophin receptor (p75(NTR)) and sortilin, proposing that sensory neuron subpopulations undergo proneurotrophin-induced apoptosis in a similar manner to what can be observed in the CNS following injury. To further investigate this hypothesis we induced sciatic nerve injury in sortilin-deficient mice, thereby preventing apoptotic signaling of proneurotrophins via the sortilin-p75(NTR) receptor complex. Using an unbiased stereological approach we found that loss of sortilin did not prevent the injury-induced loss of DRG neurons. This result demonstrates that previous findings linking p75(NTR) and proneurotrophins to loss of sensory neurons need to involve sortilin-independent pathways and suggests that proneurotrophins may elicit different functions in the CNS and PNS.

Late gestation under- and overnutrition have differential impacts when combined with a post-natal obesogenic diet on glucose-lactate-insulin adaptations during metabolic challenges in adolescent sheep

AIM

To determine whether late gestation under- and overnutrition programme metabolic plasticity in a similar way, and whether metabolic responses to an obesogenic diet in early post-natal life depend on the foetal nutrition history.

METHODS

In a 3 × 2 factorial design, twin-pregnant ewes were for the last 6 weeks of gestation (term = 147 days) assigned to HIGH (N = 13; 150 and 110% of energy and protein requirements, respectively), NORM (N = 9; 100% of requirements) or LOW (N = 14; 50% of requirements) diets. The twin offspring were raised on high-carbohydrate-high-fat (HCHF; N = 35) or conventional (CONV; N = 35) diets from 3 days to 6 months of age (around puberty). Then intravenous glucose (GTT; overnight fasted), insulin (ITT; fed) and propionate (gluconeogenetic precursor; PTT; both fed and fasted) tolerance tests were conducted to evaluate (hepatic) metabolic plasticity.

RESULTS

Prenatal malnutrition differentially impacted adaptations of particularly plasma lactate followed by glucose, cholesterol and insulin. This was most clearly expressed during PTT in fasted lambs and much less during ITT and GTT. In fasted lambs, propionate induced more dramatic increases in lactate than glucose, and HIGH lambs became more hyperglycaemic, hyperlactataemic and secreted less insulin compared to the hypercholesterolaemic LOW lambs. Propionate-induced insulin secretion was virtually abolished in fasted HCHF lambs, but upregulated in fasted compared to fed CONV lambs. HCHF lambs had the greatest glucose-induced insulin secretory responses.

CONCLUSION

Prenatal malnutrition differentially programmed glucose-lactate metabolic pathways and cholesterol homeostasis. Prenatal overnutrition predisposed for hyperglycaemia and hyperlactataemia, whereas undernutrition predisposed for hypercholesterolaemia upon exposure to an obesogenic diet. Prenatal overnutrition (not undernutrition) interfered with pancreatic insulin secretion by non-glucose-dependent mechanisms.

Late gestation over- and undernutrition predispose for visceral adiposity in response to a post-natal obesogenic diet, but with differential impacts on glucose-insulin adaptations during fasting in lambs

AIM

To investigate if late gestation under- or overnutrition has similar adverse impacts on visceral adiposity, metabolic and endocrine function in sheep, and if subsequent exposure to a high-fat diet in early post-natal life exaggerates the prenatal programming outcomes later in life.

METHODS

Thirty-six twin-pregnant ewes were fed a NORM (fulfilling 100% of daily requirements for energy and protein), LOW (50% of NORM) or HIGH diet (150% of energy and 110% of protein requirements) during the last 6 weeks of gestation (term = 147 days). Post-natally, the twin lambs were subjected to a high-fat or a moderate diet until 6 months of age (around puberty), where metabolic and endocrine adaptability to fasting was examined, and subgroups of animals were killed.

RESULTS

Animals exposed to either prenatal under- or overnutrition had reduced subcutaneous fat deposition when fed a high-fat diet, resulting in higher ratios of mesenteric and peri-renal fat relative to subcutaneous fat compared to controls. This was not related to prenatal influences on plasma glucose or insulin. Irrespective of the prenatal diet, high-fat-fed lambs underwent changes resembling the metabolic syndrome with higher plasma glucose, cholesterol, non-esterified fatty acids, triglyceride and lactate combined with abdominal obesity. Peri-renal fat appeared to be a particular target of a high-fat diet post-natally.

CONCLUSION

Both prenatal under- and overnutrition predisposed for abdominal adiposity, apparently by reducing the expandability of subcutaneous adipose tissue and induced differential physiological adaptations to fasting. This study does not suggest that exposure to gestational overnutrition will provide a protective effect against development of hyperglycaemia later in life.

Prenatal undernutrition and postnatal overnutrition alter thyroid hormone axis function in sheep

Mounting evidence led us to hypothesize that i) function of the thyroid hormone (TH) axis can be programed by late gestation undernutrition (LG-UN) and ii) early-postnatal-life overnutrition (EL-ON) exacerbates the fetal impacts on TH axis function. In a 2 × 2 factorial experiment, 21 twin-bearing sheep were fed one of two diets during late gestation: NORM (fulfilling energy and protein requirements) or LOW (50% of NORM). From day 3 to 6 months after birth (around puberty), the twin lambs were assigned to each their diet: conventional (CONV) or high-carbohydrate, high-fat, where after half the lambs were killed. Remaining sheep (exclusively females) were fed the same moderate diet until 2 years of age (young adults). At 6 months and 2 years of age, fasting challenges were conducted and target tissues were collected at autopsy. LG-UN caused adult hyperthyroidism associated with increased thyroid expression of genes regulating TH synthesis and deiodination. In one or more of the target tissues, liver, cardiac muscle, and longissimus dorsi muscle, gene expressions were increased by LG-UN for TH receptors (THRA and THRB) and deiodinases but were decreased in visceral and subcutaneous adipose tissues. EL-ON increased TH levels in adolescent lambs, but this was reversed after diet correction and not evident in adulthood. We conclude that LG-UN programed TH axis function at the secretory level and differentially in target tissues, which was increasingly manifested with age. Differential TH signaling in adipose vs other tissues may be part of a mechanism whereby fetal malnutrition can predispose for obesity and other metabolic disorders.

White matter lesion load increases the risk of low CSF Aβ42 in apolipoprotein E-ɛ4 carriers attending a memory clinic

BACKGROUND

White matter lesions (WMLs) are age-related manifestations of ischemic cerebrovascular disease and increase the risk for Alzheimer's disease (AD). The apolipoprotein E (ApoE) ɛ4 allele is a risk factor for late onset AD and has been related to low cerebrospinal fluid (CSF) Aβ42 levels and to cerebrovascular disease. The present study analyzed the relationship between WMLs, ApoE-ɛ4 genotype, and low CSF Aβ42.

METHODS

A total of 235 memory clinic attenders were stratified in 3 groups according to WML load. WMLs were rated on axial T2 magnetic resonance imaging images. Group 1 had no or only small amounts of periventricular (PV) or subcortical (SC) WMLs, WML group 2 had high amounts of PV WMLs and low amounts of SC WMLs, and WML group 3 had high amounts of both PV and SC WMLs. In each WML group, ApoE-ɛ4 genotype was used in logistic regression as a predictor for low CSF Aβ42 (cutoff≤450 ng/L).

RESULTS

The odds ratio (OR) of having low CSF Aβ42 was significantly increased in the presence of ApoE-ɛ4 only in WML group 3 (OR 3.69, P=.009).

CONCLUSION

A high WML load may interact with the ApoE-ɛ4 genotype and increase the risk for reduced CSF Aβ42 in patients attending a memory clinic.

Effects of cerebrovascular disease on amyloid precursor protein metabolites in cerebrospinal fluid

Background

Alzheimer's disease (AD) and cerebrovascular disease (CVD) including chronic small vessel disease of the brain (SVD) are the most frequent causes of dementia. AD is associated with metabolism of amyloid precursor protein (APP) and low levels of amyloid-β peptide (Aβ) X-42 in the cerebrospinal fluid (CSF). CVD and SVD are established risk factors for AD, brain white matter lesions (WML) are established surrogate markers for SVD and are also associated with reduced CSF AβX-42.

A cohort survey was performed to examine whether SVD or acute CVD affects APP metabolism and to explore a potential association between WML and APP metabolism in two groups; cognitively impaired patients, subjective and mild (SCI and MCI) and stroke patients. Through measurements of CSF APP metabolite levels in patients with a wide range of WML volumes, this study aimed to determine how SVD influences APP metabolism.

Methods

Sixty-three patients were included: 37 with subjective cognitive impairment (SCI) or mild cognitive impairment (MCI) without stroke, and 26 after acute stroke. Chronic and acute WML volume and infarct volume were determined by magnetic resonance imaging (MRI) post-scan processing, and CSF levels of α- and β-cleaved soluble APP (sAPP-α and sAPP-β, AβX-38, AβX-40 and AβX-42) were determined. The Mann-Whitney test was used to compare the patient groups. Chronic and acute WML volumes, infarct volume, age, and sex were used as predictors for CSF biomarker levels in linear regression analysis.

Results

CSF levels of sAPP-α and sAPP-β were strongly correlated (r = 0.95, p < 0.001) and lower levels of these biomarkers were found in the stroke group than in the SCI/MCI group; median sAPP-α 499.5 vs. 698.0 ng/mL (p < 0.001), sAPP-β 258.0 vs. 329.0 ng/mL (p < 0.005). CSF levels of sAPP-α, sAPP-β, AβX-38, AβX-40 and AβX-42 were inversely correlated with chronic WML volume (p ≤ 0.005; p ≤ 0.01; p ≤ 0.01; p ≤ 0.05; p ≤ 0.05 respectively), but not with acute WML or infarct volumes.

Conclusions

Lower CSF levels of sAPP-α and sAPP-β in the stroke group than in the SCI/MCI group and an inverse correlation with chronic WML indicate that ischemia lowers the levels of CSF sAPP metabolites and suggests that APP axonal transport or metabolism may be affected in SVD of the brain.

Determination of ethylglucuronide in oral fluid by ultra-performance liquid chromatography- tandem mass spectrometry

An ultra-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for the determination of ethylglucuronide (EtG) in oral fluid. Sample clean-up was achieved by solid-phase extraction with a Hyper-SEP SAX column. Negative ionization was performed in the multiple reaction monitoring mode. Two transitions were monitored for the analyte and one for the internal standard EtG-d(5). The calibration range was 4.4-222 ng/mL. The recovery of the analyte ranged from 86 to 99%, and the between-assay precisions ranged from 5 to 9% RSD. The limit of quantification was found to be 4.4 ng/mL. The concentration of EtG in oral fluid collected 2-14 h after a moderate alcohol intake varied from 13.3 to 57.7 ng/mL.

Reduced cerebrospinal fluid BACE1 activity in multiple sclerosis

Background

Cell and animal experiments have shown that β-site APP-cleaving enzyme 1 (BACE1) may be involved in myelination.

Objective

Here, we assess the association of cerebrospinal fluid (CSF) BACE1 activity with multiple sclerosis (MS).

Methods

BACE1 activity and levels of secreted amyloid precursor protein (APP) and amyloid-β (Aβ) isoforms were analyzed in CSF from 100 patients with MS and 114 neurologically healthy controls. Patients with systemic lupus erythematosus (SLE), 26 with and 41 without cerebral engagement, were also included to enable comparisons with regards to another autoimmune disease. A subset of patients with MS and controls underwent a second lumbar puncture after 10 years.

Results

MS patients had lower CSF BACE1 activity than controls ( P = 0.03) and patients with cerebral SLE ( P < 0.001). Patients with cerebral SLE had higher BACE1 activity than any other group ( P < 0.05 for all comparisons). BACE1 activity correlated with the different amyloid markers in all study groups. BACE1 activity decreased over 10 years in the MS group ( P = 0.039) and correlated weakly with clinical disease severity scores in an inverse manner.

Conclusions

These results suggest an involvement of BACE1 in the MS disease process.

White matter lesion severity is associated with reduced cognitive performances in patients with normal CSF Abeta42 levels

OBJECTIVE

To identify possible associations between white matter lesions (WML) and cognition in patients with memory complaints, stratified in groups with normal and low cerebrospinal fluid (CSF) Abeta42 values.

MATERIAL AND METHODS

215 consecutive patients with subjective memory complaints were retrospectively included. Patients were stratified into two groups with normal (n = 127) or low (n = 88) CSF Abeta42 levels (cut-off is 450 ng/l). Cognitive scores from the Mini-Mental State Examination (MMSE) and the Neurobehavioral Cognitive Status Examination (Cognistat) were used as continuous dependent variables in linear regression. WML load was used as a continuous independent variable and was scored with a visual rating scale. The regression model was corrected for possible confounding factors.

RESULTS

WML were significantly associated with MMSE and all Cognistat subscores except language (repetition and naming) and attention in patients with normal CSF Abeta42 levels. No significant associations were observed in patients with low CSF Abeta42.

CONCLUSIONS

WML were associated with affection of multiple cognitive domains, including delayed recall and executive functions, in patients with normal CSF Abeta42 levels. The lack of such associations for patients with low CSF Abeta42 (i.e. with evidence for amyloid deposition), suggests that amyloid pathology may obscure cognitive effects of WML.

Associations between white matter lesions, cerebrovascular risk factors, and low CSF Abeta42

OBJECTIVE

To analyze a putative relationship between white matter lesions (WMLs), risk factors for WMLs, and Alzheimer disease (AD) as measured with the surrogate marker CSF Abeta42.

METHODS

The authors analyzed effects of acquired risk factors for cerebrovascular disease and WMLs on AD as measured with an intermediate marker, CSF Abeta42. A total of 127 consecutive patients with subjective memory impairment (mean age 66 years; 57 women) investigated at a university-based memory clinic had brain MRI scans. WMLs were rated on a 12-point scale with a semiquantitative procedure. They used path analysis with established and possible risk factors for WMLs and for reduced CSF Abeta42 (age, hypertension, hyperhomocysteinemia, hypercholesterolemia, APOE-epsilon4) as variables.

RESULTS

The WML score was 1.5 points higher (p < 0.05) in hypertensive than in nonhypertensive patients and 1.9 points higher (p < 0.05) in patients with hyperhomocysteinemia than in those with normal homocysteine levels. Hypercholesterolemia increased the probability of low CSF Abeta42 levels by 0.2 (p < 0.05). For each point increase in WML score, the probability of low CSF Abeta42 levels increased by 0.03 (p < 0.05). APOE-epsilon4 was associated with reduced CSF Abeta42 (p < 0.01).

CONCLUSION

Both hypercholesterolemia and white matter lesions may contribute to low CSF Abeta42 by independent mechanisms.

Assessing behaviour in children emerging from anaesthesia: can we apply psychiatric diagnostic techniques?

BACKGROUND

No standardized instrument exists for the systematic analysis of emergence behaviour in children after anaesthesia. Our purpose was to evaluate children's behaviour prior to anaesthetic induction and immediately upon emergence to develop an assessment tool using psychiatric terminology and techniques.

METHODS

This prospective study evaluated 25 children from 2 to 9 years of age for preanaesthetic psychosocial factors that might affect behaviour. Children's behaviour was observed from admission to the surgical unit through the induction of anaesthesia. All children received a standardized premedication and induction of anaesthesia. The maintenance anaesthetic was randomized to intravenous remifentanil or inhaled isoflurane. All children underwent repair of strabismus. We assessed the behaviour of children for 30 min upon emergence from anaesthesia for symptoms of pain, distress and delirium using an assessment tool we developed guided by the principles of psychiatry as described in Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).

RESULTS

Using our assessment tool, 44% of children demonstrated altered behaviour on emergence; 20% demonstrated complex symptoms with characteristics of delirium. Children anaesthetized with isoflurane had significantly higher postanaesthesia behaviour assessment scores than those anaesthetized with remifentanil (P = 0.04). Age was a significant variable; children <62 months were more prone to altered behaviour than those >62 months (P = 0.02). Scores did not correlate with preanaesthetic risk factors including preexisting psychological or social variables or observed preanaesthetic distress. There was no delay in hospital discharge in children assessed as having altered behaviour.

CONCLUSIONS

This exploratory study suggests that postanaesthetic behaviour abnormalities with characteristics of distress or delirium can be categorized using known DSM-IV terminology; in our cohort this behaviour was dependent on age and anaesthetic technique.

Mice with a targeted deletion of the tetranectin gene exhibit a spinal deformity

Tetranectin is a plasminogen-binding, homotrimeric protein belonging to the C-type lectin family of proteins. Tetranectin has been suggested to play a role in tissue remodeling, due to its ability to stimulate plasminogen activation and its expression in developing tissues such as developing bone and muscle. To test the functional role of tetranectin directly, we have generated mice with a targeted disruption of the gene. We report that the tetranectin-deficient mice exhibit kyphosis, a type of spinal deformity characterized by an increased curvature of the thoracic spine. The kyphotic angles were measured on radiographs. In 6-month-old normal mice (n = 27), the thoracic angle was 73 degrees +/- 2 degrees, while in tetranectin-deficient 6-month-old mice (n = 35), it was 93 degrees +/- 2 degrees (P < 0.0001). In approximately one-third of the mutant mice, X-ray analysis revealed structural changes in the morphology of the vertebrae. Histological analysis of the spines of these mice revealed an apparently asymmetric development of the growth plate and of the intervertebral disks of the vertebrae. In the most advanced cases, the growth plates appeared disorganized and irregular, with the disk material protruding through the growth plate. Tetranectin-null mice had a normal peak bone mass density and were not more susceptible to ovariectomy-induced osteoporosis than were their littermates as determined by dual-emission X-ray absorptiometry scanning. These results demonstrate that tetranectin plays a role in tissue growth and remodeling. The tetranectin-deficient mouse is the first mouse model that resembles common human kyphotic disorders, which affect up to 8% of the population.

Engineering increased stability in the antimicrobial peptide pediocin PA-1

Pediocin PA-1 is a food grade antimicrobial peptide that has been used as a food preservative. Upon storage at 4 degrees C or room temperature, pediocin PA-1 looses activity, and there is a concomitant 16-Da increase in the molecular mass. It is shown that the loss of activity follows first-order kinetics and that the instability can be prevented by replacing the single methionine residue (Met31) in pediocin PA-1. Replacing Met by Ala, Ile, or Leu protected the peptide from oxidation and had only minor effects on bacteriocin activity (for most indicator strains 100% activity was maintained). Replacement of Met by Asp was highly deleterious for bacteriocin activity.

A C-terminal disulfide bridge in pediocin-like bacteriocins renders bacteriocin activity less temperature dependent and is a major determinant of the antimicrobial spectrum

Several lactic acid bacteria produce so-called pediocin-like bacteriocins that share sequence characteristics, but differ in activity and target cell specificity. The significance of a C-terminal disulfide bridge present in only a few of these bacteriocins was studied by site-directed mutagenesis of pediocin PA-1 (which naturally contains the bridge) and sakacin P (which lacks the bridge). Introduction of the C-terminal bridge into sakacin P broadened the target cell specificity of this bacteriocin, as illustrated by the fact that the mutants were 10 to 20 times more potent than the wild-type toward certain indicator strains, whereas the potency toward other indicator strains remained essentially unchanged. Like pediocin PA-1, disulfide-containing sakacin P mutants had the same potency at 20 and 37 degrees C, whereas wild-type sakacin P was approximately 10 times less potent at 37 degrees C than at 20 degrees C. Reciprocal effects on target cell specificity and the temperature dependence of potency were observed upon studying the effect of removing the C-terminal disulfide bridge from pediocin PA-1 by Cys-->Ser mutations. These results clearly show that a C-terminal disulfide bridge in pediocin-like bacteriocins contributes to widening of the antimicrobial spectrum as well as to higher potency at elevated temperatures. Interestingly, the differences between sakacin P and pediocin PA-1 in terms of the temperature dependency of their activities correlated well with the optimal temperatures for bacteriocin production and growth of the bacteriocin-producing strain.

A kinetic assay to determine prothrombin binding to membranes

Activation of prothrombin by multisquamase, the prothrombin activator from the venom of Echis multisquamatus (Central Asian sand viper), is inhibited by membranes containing negatively charged anionic phospholipids. This inhibition appears to be due to the fact that the venom activator cannot activate membrane-bound prothrombin. Initial steady state rates of prothrombin activation by multisquamase in the presence of phospholipids appeared to depend on the fraction unbound prothrombin only and this phenomenon was used to quantitate binding of prothrombin to membranes of varying phospholipid composition. In this method, the initial rate of prothrombin activation by multisquamase is measured in the absence (total prothrombin) and in the presence of a procoagulant surface (rate depending only on free prothrombin) and from the difference in activation rates the amount of membrane-bound prothrombin is calculated. The validity of the method was established by determination of the binding parameters for prothrombin binding to 100 microM phospholipid vesicles composed of 20 mole% phosphatidylserine and 80 mole% phosphatidylcholine. The binding parameters obtained were Kd=0.84 microM and n=0.021 micromoles prothrombin bound per micromole phospholipid which is in agreement with literature. Due to the nature of the measurement the method is especially suitable to quantitate binding of prothrombin at concentrations as low as 5 nM prothrombin.