EEG functional connectivity and ApoE genotype in Alzheimer's disease and controls

OBJECTIVE

We examined the relation between Apolipoprotein E epsilon4 allele (ApoE epsilon4) genotype and functional connectivity measured by Electroencephalography (EEG) in patients with Alzheimer's disease (AD) and patients with subjective complaints (SC).

METHODS

We included 43 patients with AD (age (SD)=74.2 (4.0), m/f=22/21; 30 of ApoE epsilon4 carriers) and 21 patients with SC (age (SD)=73.2 (5.2), m/f=13/8; 7 ApoE epsilon4 carriers) for this study. Resting state EEGs were recorded in all subjects. Synchronisation likelihood (SL) between local cortical areas was compared in the alpha and beta band according to ApoE epsilon4 status and diagnosis.

RESULTS

ApoE epsilon4 carriers had higher SL values in lower and upper alpha band, in both diagnostic groups. In upper alpha band and beta band AD patients had lower SL than patients with SC, was irrespective of ApoE status.

CONCLUSION

The effects of AD and ApoE epsilon4 on functional connectivity are opposite and independent.

SIGNIFICANCE

The observed increase in SL in both AD and patients with SC carrying ApoE epsilon4 suggests a strong genetic impact of ApoE epsilon4 on brain function.

Whole-brain atrophy rate and CSF biomarker levels in MCI and AD: a longitudinal study

OBJECTIVES

To assess associations between cerebrospinal fluid (CSF) biomarker levels and MRI-based whole-brain atrophy rate in mild cognitive impairment (MCI) and Alzheimer's disease (AD).

METHODS

We included 99 patients (47 AD, 29 MCI, 23 controls) who underwent lumbar puncture at baseline and repeat MRI. A subgroup of 48 patients underwent a second lumbar puncture. CSF levels of beta-amyloid(1-42) (A beta(1-42)), tau and tau phosphorylated at threonine-181 (P-tau(181)), and whole-brain atrophy rate were measured.

RESULTS

Across groups, baseline A beta(1-42) and tau were modestly associated with whole-brain atrophy rate. Adjusted for age, sex and diagnosis, we found no association between A beta(1-42) or tau, and whole-brain atrophy rate. By contrast, high CSF levels of P-tau(181) showed a mild association with a lower whole-brain atrophy rate in AD but not in controls or MCI patients. Finally, whole-brain atrophy rate was associated with change in MMSE, but change in CSF biomarker levels was not.

CONCLUSIONS

Whole-brain atrophy rate and CSF levels of A beta(1-42,) tau or P-tau(181) provide complementary information in patients with MCI and AD.

Distribution of APOE genotypes in a memory clinic cohort

AIM

To describe the distribution of apolipoprotein E (APOE) genotypes in a cohort of memory clinic patients.

METHODS

We included 749 memory clinic patients. Diagnoses were made in a multidisciplinary consensus meeting and the APOE genotype was determined. The community-based cohort of the Longitudinal Aging Study Amsterdam was used as control population (n = 2,233).

RESULTS

In the memory clinic sample, there were 173 patients with subjective complaints, 125 patients with mild cognitive impairment (MCI), 251 patients with Alzheimer disease (AD), 107 patients with another type of dementia, and 93 patients with another neurologic or psychiatric diagnosis. The APOE allele distribution differed among groups. There was no difference in the prevalence of the epsilon2 allele, but there were differences in distribution of the epsilon3 and epsilon4 alleles. Compared with the control population (15%), the prevalence of APOE epsilon4 was increased among patients with subjective complaints (22%), MCI (36%), AD (42%) and other types of dementia (25%).

CONCLUSION

We observed an increased prevalence of APOE epsilon4 in patients with MCI and subjective complaints. This finding is of great clinical importance as nondemented patients positive for APOE epsilon4 could be identified as being at genetic risk of AD, and for that reason monitored more closely.

A novel method to identify syncytiotrophoblast-derived RNA products representative of trisomy 21 placental RNA in maternal plasma

A novel in vitro method is described wherein gene expression profiling is reflective and informative for the way how syncytiotrophoblast cells shed RNA products in vivo in maternal plasma. After controlled denudation, RNA is obtained selectively from the syncytiotrophoblast cells of trisomy 21 placentae. cDNA copies are subsequently analyzed by microarray profiling and cDNA cloning with sequencing. Given the preponderance of 5' mRNA fragments lacking a poly-A tail, the placental RNA products are amplified after polymerase A-mediated tailing by using a method originally designed for small-sized microRNAs. This approach, when combined with cDNA library or microarray expression screening, is a novel in vitro method to screen for syncytiotrophoblast-derived RNA products representative of trisomy 21 placental RNA as present in vivo in maternal plasma.

Whole-brain atrophy rate in Alzheimer disease: identifying fast progressors

OBJECTIVE

To assess which baseline clinical and MRI measures influence whole-brain atrophy rates, measured from serial MR imaging.

METHODS

We recruited 65 patients with Alzheimer disease (mean +/- SD age 70 +/- 8 y, 58% women, Mini-Mental State Examination [MMSE] 22 +/- 5), scanned with an average interval of 1.7 +/- 0.6 years. Whole-brain atrophy rates were used as outcome measure. Baseline normalized brain volume, hippocampal volume, and whole-brain atrophy rates were measured using three-dimensional T1-weighted imaging. The influence of age, sex, apolipoprotein E genotype (APOE), baseline MMSE, baseline hippocampal volume, and baseline normalized brain volume on whole-brain atrophy rates was assessed using linear regression.

RESULTS

The mean whole-brain atrophy rate was -1.9 +/- 0.9% per year. In the multivariate model, younger age (beta [SE] = 0.03 [0.01]; p = 0.04), absence of APOE epsilon 4 (beta [SE] = 0.61 [0.28]; p = 0.03), and a low MMSE (beta [SE] = 0.11 [0.03]; p < 0.001) were associated with a higher whole-brain atrophy rate. Furthermore, a relatively spared hippocampus predicted faster decline for patients with a smaller baseline brain volume (p = 0.09), and with a lower MMSE (p = 0.07). Finally, a smaller brain volume was associated with a higher rate of atrophy in younger patients (p = 0.03).

CONCLUSIONS

Our results suggest it is possible to characterize a subgroup of patients with Alzheimer disease (AD) who are at risk of faster loss of brain volume. Patients with more generalized, rather than focal hippocampal atrophy, who often have an onset before the age of 65, and are APOE epsilon 4 negative, seem to be at risk of faster whole-brain atrophy rates than the more commonly seen patients with AD, who are older, are APOE epsilon 4 positive, and have pronounced hippocampal atrophy.

Hypertrophy of mature Xenopus muscle fibres in culture induced by synergy of albumin and insulin

The aim of this study was to investigate effects of albumin and insulin separately as well as in combination on mature muscle fibres during long-term culture. Single muscle fibres were dissected from m. iliofibularis of Xenopus laevis and attached to a force transducer in a culture chamber. Fibres were cultured in a serum-free medium at slack length (mean sarcomere length 2.3 mum) for 8 to 22 days. The medium was supplemented with (final concentrations): (1) bovine insulin (6 nmol/L or 200-600 nmol/L), (2) 0.2% bovine albumin or (3) 0.2% bovine albumin in combination with insulin (120 nmol/L). In culture medium with insulin, 50% of the muscle fibres became in-excitable within 7-12 days, whereas the other 50% were stable. Caffeine contractures of in-excitable muscle fibres produced 80.4 +/- 2.4% of initial peak tetanic force, indicating impaired excitation-contraction (E-C) coupling in in-excitable fibres. In the presence of albumin, all cultured muscle fibres were stable for at least 10 days. Muscle fibres cultured in medium with insulin or albumin exclusively did not hypertrophy or change the number of sarcomeres in series. In contrast, muscle fibres cultured with both albumin and insulin showed an increase in tetanic force and fibre cross-sectional area of 19.6 +/- 2.8% and 32.5 +/- 4.9%, respectively, (means +/- SEM.; P = 0.007) after 16.3 +/- 1.7 days, whereas the number of sarcomeres in series remained unchanged. We conclude that albumin prevents muscle fibre damage and preserves E-C coupling in culture. Furthermore, albumin is important in regulating muscle fibre adaptation by a synergistic action with growth factors like insulin.

Inflammatory markers in AD and MCI patients with different biomarker profiles

OBJECTIVE

The aim of this study was to demonstrate the involvement of the inflammatory proteins IL-6, ACT and CRP early in the pathology process of AD in patients with mild cognitive impairment (MCI) and AD.

METHODS

IL-6, ACT, CRP, Abeta42, phospho-tau (p-tau) and total tau concentrations in serum and CSF of 145 patients with probable AD and 67 patients with MCI were measured by sandwich ELISA. MCI patients were characterized as high- respectively low-risk MCI according to their Abeta42/tau risk profile.

RESULTS

CSF and serum CRP levels were significantly higher in MCI compared to AD patients after adjustment for age, ApoE epsilon4 genotype and cardiovascular diseases (p<0.01). This difference remained present in patients with a low-risk biomarker profile for AD after adjustment for abovementioned covariates. CSF IL-6 levels were also significantly higher in MCI patients with a low-risk CSF profile.

CONCLUSIONS

These findings suggest that inflammatory processes might be involved in early stages of AD, even before Abeta and tau changes are present in CSF of MCI patients.

CSF biomarker levels in early and late onset Alzheimer's disease

OBJECTIVE

To compare CSF levels of beta-amyloid 1-42 (Abeta(1-42)), total tau (tau) and tau phosphorylated at threonine 181 (ptau-181) between AD patients and controls according to age.

METHODS

248 AD patients (48% men) and 127 controls (51% men, 22 volunteers and 105 subjective complainers) underwent lumbar puncture. Both patients and controls were divided into a young (<65 years) and old (>or=65 years) group.

RESULTS

All three biomarkers showed main effects of diagnosis (p<0.001). There was an interaction between diagnosis and age for all three biomarkers (p<0.05), as old controls had lower Abeta(1-42) and higher (p)tau than young controls (Abeta(1-42) 699+/-250 versus 866+/-191pg/ml, tau 408+/-245 versus 243+/-102pg/ml, ptau-181 60+/-28 versus 42+/-15pg/ml), but there was no difference according to age among AD patients (Abeta(1-42) 451+/-178 versus 425+/-146pg/ml, tau 741+/-460 versus 798+/-467pg/ml, ptau-181 91+/-42 versus 91+/-41pg/ml).

CONCLUSION

We found that the older control group had lower Abeta(1-42) and higher (p)tau compared to the younger control group. This suggests that older individuals may have AD pathology, even in the absence of objective cognitive impairment.

H9c2 cardiomyoblasts produce thyroid hormone

Thyroid hormone acts on a wide range of tissues. In the cardiovascular system, thyroid hormone is an important regulator of cardiac function and cardiovascular hemodynamics. Although some early reports in the literature suggested an unknown extrathyroidal source of thyroid hormone, it is currently thought to be produced exclusively in the thyroid gland, a highly specialized organ with the sole function of generating, storing, and secreting thyroid hormone. Whereas most of the proteins necessary for thyroid hormone synthesis are thought to be expressed exclusively in the thyroid gland, we now have found evidence that all of these proteins, i.e., thyroglobulin, DUOX1, DUOX2, the sodium-iodide symporter, pendrin, thyroid peroxidase, and thyroid-stimulating hormone receptor, are also expressed in cardiomyocytes. Furthermore, we found thyroglobulin to be transiently upregulated in an in vitro model of ischemia. When performing these experiments in the presence of 125 I, we found that 125 I was integrated into thyroglobulin and that under ischemia-like conditions the radioactive signal in thyroglobulin was reduced. Concomitantly we observed an increase of intracellularly produced, 125 I-labeled thyroid hormone. In conclusion, our findings demonstrate for the first time that cardiomyocytes produce thyroid hormone in a manner adapted to the cell's environment.

Measurement of Allelic-Expression Ratios in Trisomy 21 Placentas by Quencher Extension of Heterozygous Samples Identified by Partially Denaturing HPLC

Background: Measuring the allelic ratios of placental transcripts in maternal plasma permits noninvasive prenatal detection of chromosomal aneuploidy. Current methods, however, require highly specialized equipment (MALDI-TOF), limiting the widespread implementation of this powerful RNA single-nucleotide polymorphism (SNP) strategy in routine diagnostic settings. We adapted and applied the Transgenomic WAVE System and quencher extension (QEXT) for this purpose.

Methods: The expressed SNP (rs2187247) in exon 2 of the placentally expressed C21orf105 gene (chromosome 21 open reading frame 105) on chromosome 21 was tested in a trisomy 21 model system in which we obtained RNA selectively released from syncytiotrophoblasts of normal and trisomy 21 placentas during first trimester.

Results: In identifying heterozygous samples, we observed an exact correspondence between sequencing results and results obtained with the WAVE System. With respect to the analysis time required, the WAVE System was superior. In addition, the real-time QEXT assay (as optimized and validated with calibration standards consisting of 262-bp C21orf105 cDNA amplicons) accurately measured allele ratios after we optimized fragment purification, concentrations of input DNA and quencher label, and calculations of reporter signals. Finally, the optimized and validated QEXT assay correctly distinguished normal placentas from trisomy 21 placentas in tests of the following clinically relevant combinations: diploid homozygous (CC), diploid heterozygous (AC), triploid homozygous (AAA), and triploid heterozygous (AAC or ACC).

Conclusion: The QEXT method, which is directly adaptable to current real-time PCR equipment, along with rapid identification of informative samples with the WAVE System, may facilitate routine implementation of the RNA-SNP assay for noninvasive aneuploidy diagnostics.

Longitudinal changes of CSF biomarkers in memory clinic patients

OBJECTIVE

In Alzheimer disease (AD), longitudinal changes of beta-amyloid(1-42) (Abeta(1-42)), tau, and phosphorylated tau at threonine 181 (ptau-181) in CSF have been reported in small studies only. We evaluated the natural course of CSF biomarkers in patients with AD, subjective complaints, and mild cognitive impairment (MCI).

METHODS

One hundred five patients (50 AD, 38 MCI, 17 subjective complaints) underwent two lumbar punctures, with a mean interval of 21 +/- 9 months. CSF levels of Abeta(1-42), tau, and ptau-181 were measured.

RESULTS

CSF Abeta(1-42) and tau levels showed main effects for both diagnosis and time (all p < 0.05), with average increases of 47 +/- 72 and 49 +/- 143 pg/mL. The interaction terms were not significant, which implies a similar time effect for all diagnostic groups. CSF ptau-181 levels showed a main effect for diagnosis (p = 0.01) but not for time (p = 0.27, increase of 1.0 +/- 12 pg/mL).

CONCLUSION

Levels of CSF beta-amyloid(1-42) and tau but not phosphorylated tau at threonine 181 increased over time in this memory clinic patient cohort with comparable change in all diagnostic groups. The cross-sectional difference between diagnostic groups, however, exceeded by far the longitudinal changes within individuals, suggesting that these biomarkers are not sensitive as markers of disease progression.

Effect of raloxifene treatment on osteocyte apoptosis in postmenopausal women

Increased osteocyte apoptosis, as the result of estrogen deficiency, could play a role in the decrease of bone mass and bone strength seen in postmenopausal osteoporosis. We investigated whether treatment with raloxifene of postmenopausal women with osteoporosis affects osteocyte apoptosis. Transiliac bone biopsies were obtained from 26 osteoporotic women at baseline and after 2 years of treatment with placebo or raloxifene. Immunohistochemical detection of cleaved caspase-3 was performed on sections from nondecalcified bone biopsies to visualize apoptosis. In the trabecular bone total osteocytes, positively stained osteocytes and empty lacunae were counted and percent positive cells and percent empty lacunae determined. Statistical evaluation was performed by Wilcoxon's paired t-test and Spearman's rank correlations. There was no significant difference in percentage positive osteocytes between baseline and follow-up biopsies in both the placebo and the raloxifene groups. The percentage empty lacunae increased significantly in the placebo group (11.20 +/- 1.43 vs. 9.00 +/- 2.25, P = 0.014) but not in the raloxifene group. At baseline in both groups combined, there was a negative correlation between indices of bone remodeling and the percentage positive osteocytes (bone formation rate/bone volume r = -0.67, P = 0.001). We found no direct evidence for an effect of raloxifene treatment on osteocyte apoptosis, but small effects of raloxifene treatment cannot be excluded. The percent of apoptotic osteocytes was dependent on the level of bone remodeling in an individual.