Effects of dietary phosphate and calcium intake on fibroblast growth factor-23

BACKGROUND AND OBJECTIVES

Little is known about the influence of dietary phosphate intake on fibroblast growth factor-23 (FGF23) and its subsequent effects on vitamin D levels. This study addresses changes in intact FGF23 (iFGF23) and C-terminal FGF23 (cFGF23), phosphaturia, and levels of vitamin D on high and low phosphate and calcium intake.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Ten healthy subjects adhered to a diet low or high in phosphate and calcium content for 36 hours each with a 1-week interval during which subjects adhered to their usual diet. Serum phosphate, calcium, vitamin D metabolites, parathyroid hormone (PTH), and FGF23 levels (cFGF23 and iFGF23) were measured several times a day. Phosphate, calcium, and creatinine excretion was measured in 24-hour urine on all study days.

RESULTS

Serum phosphate levels and urinary phosphate increased during high dietary phosphate intake (from 1.11 to 1.32 mmol/L, P<0.0001 and 21.6 to 28.8 mmol/d, P=0.0005, respectively). FGF23 serum levels increased during high dietary phosphate/calcium intake (cFGF23 from 60 to 72 RU/ml, P<0.001; iFGF23 from 33 to 37 ng/L, P=0.003), whereas PTH declined. 1,25-dihydroxyvitamin D (1,25D) showed an inverse relation with FGF23.

CONCLUSIONS

Variation in dietary phosphate and calcium intake induces changes in FGF23 (on top of a circadian rhythm) and 1,25D blood levels as well as in urinary phosphate excretion. These changes are detectable the day after the change in the phosphate content of meals. Higher FGF23 levels are associated with phosphaturia and a decline in 1,25D levels.

Reproducibility and reliability of repeated semen analyses in male partners of subfertile couples

OBJECTIVE

To determine the precise degree of variability that is represented by the reproducibility and reliability of semen analysis. The general assumption is that semen analyses need to be repeated because of a high degree of within-individual variability. However, the precise degree of variability is not well established in male partners of subfertile couples.

DESIGN

Retrospective cohort study.

SETTING

Two university hospitals in the Netherlands, which routinely perform two semen analyses in the male partner of subfertile couples.

PATIENT(S)

Male partners of subfertile couples.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

We assessed the test-retest reproducibility, by calculating the coefficient of variation (CV(w)) for five semen parameters. The CV(w) expresses, on a relative scale, the degree of closeness of repeated measurements taken in the same subject. We also estimated the reliability of these semen parameters, in terms of the intraclass correlation coefficient, which expresses the ratio of the between-subject variability over the total variability.

RESULT(S)

We analyzed the data of 5,240 men and found that the CV(w) of all semen parameters ranged from 28% to 34%. The intraclass correlation coefficients of these semen parameters were moderate to high: volume: 0.70; concentration: 0.89; motility: 0.58; morphology: 0.60; total motile count: 0.73.

CONCLUSION(S)

This study affirmed the presumed large within-subject variability and the limited reproducibility of semen analyses in subfertile men. Whether this degree of variability within men justifies one or more repetitions of the semen analysis in view of consequences for clinical management should be the topic of future studies. Until then it seems reasonable to perform two semen analyses.

Dementia mimicking Alzheimer's disease Owing to a tau mutation: CSF and PET findings

The objective of the study was to illustrate the utility of positron emission tomography (PET) imaging using [C]PIB and [F]FDDNP together with cerebrospinal fluid (CSF) measures of amyloid-beta1 to 42 (Abeta42), total tau (t-tau) and tau phosphorylated at threonine 181 (p-tau) in the in vivo diagnosis of specific dementia syndromes. Two siblings fulfilling diagnostic criteria for familial Alzheimer's disease (AD) were investigated using [C]PIB and [F]FDDNP PET in combination with CSF measures of Abeta42, t-tau and p-tau. PET data were compared with paired [C]PIB and [F]FDDNP data from age-matched sporadic AD patients (n=9) and healthy controls (n=6). [C]PIB retention and CSF levels of Abeta42 in both patients resembled those of controls suggesting the presence of nonamyloid pathology. Genetic testing confirmed the absence of mutations in the presenilin 1 gene in 1 patient; subsequent testing revealed the R406W tau mutation in both individuals leading to a diagnosis of frontotemporal dementia [F]FDDNP retention broadly correlated with CSF levels of t-tau and p-tau. Despite both individuals harbouring the same mutation, [F]FDDNP retention and CSF t-tau and p-tau were elevated in 1 patient, but not in the other. [C]PIB imaging and CSF measures of Abeta42 are useful in refuting the presence of underlying amyloid pathology. This, in combination with elevated levels of CSF t-tau and p-tau, has potential value in differential diagnosis of frontotemporal dementia from AD.

Plasma TIMP-1 and CEA in detection of primary colorectal cancer: a prospective, population based study of 4509 high-risk individuals

OBJECTIVE

The combination of plasma tissue inhibitor of metalloproteinases-1 (TIMP-1) and carcinoembryonic antigen (CEA) may be valuable biomarkers for early detection of colorectal cancer (CRC). A prospective, population based study was performed to validate this hypothesis.

MATERIAL AND METHODS

Individuals (n = 4509) referred for large bowel endoscopy due to symptoms of CRC were prospectively included. Baseline data and concurrent diseases were recorded. The primary endpoint was detection of CRC and findings at examinations were recorded using International Classification of Diseases-10 codes. Plasma was obtained before endoscopy and TIMP-1 and CEA levels were determined after the inclusion of all individuals.

RESULTS

Findings were based on sigmoidoscopy in 1766 and colonoscopy in 2743 individuals. Colon cancer (CC) was detected in 184 and rectal cancer in 110 individuals. Ten individuals with other cancers, 856 with adenomas and 1176 with non-neoplastic findings were also detected. The biomarker levels were increased in a variety of diseases including CRC compared to individuals without any findings at endoscopy. A multivariable analysis demonstrated that both markers were significant and independent detectors of CRC. Combining both biomarkers, independent contributions from each (TIMP-1, odds ratio (OR) = 1.8 (95% confidence interval (CI): 1.4-2.2), p < 0.0001; CEA < 5 ng/ml, OR = 1.6, 1.3-1.9, or ≥ 5 ng/ml, OR = 2.3, 95% CI: 1.9-2.7 (p < 0.0001)) were obtained. Subgroup analysis of individuals examined by colonoscopy with CC as the endpoint showed that combining both biomarkers, independent contributions from each (TIMP-1, OR = 2.5, 95% CI: 1.8-3.4, p < 0.0001; CEA < 5 ng/ml, OR = 1.4, 95% CI: 1.1-1.8, and CEA ≥ 5 ng/ml, OR = 2.3, 95% CI: 1.8-3.0 (p < 0.0001)) were obtained.

CONCLUSIONS

This prospective validation study supports the use of the combination of plasma TIMP-1 and CEA protein measurements as a potential aid in early detection of CRC and specifically of CC.

EEG abnormalities in early and late onset Alzheimer's disease: understanding heterogeneity

OBJECTIVE

To compare differences in severity and type of electroencephalography (EEG) abnormalities between early and late onset Alzheimer's disease (AD) and to assess the influence of APOE genotype on this association, in order to understand the biological differences in AD according to age at onset

METHOD

Of 460 probable AD patients and 336 patients with subjective complaints, serving as controls, EEG and APOE genotype were obtained. Subjects were categorised by age into a younger (≤65 years) and an older group (>65 years), based on age at diagnosis. Severity and type of EEG abnormalities were visually assessed. Severity of EEG abnormalities ranged from normal to slightly abnormal to moderately severe. EEG abnormalities were characterised as only focal abnormalities, only diffuse abnormalities or both focal and diffuse abnormalities.

RESULTS

Logistic regression revealed that younger AD patients more often had EEG abnormalities, which were more severe, with a predominance of both focal and diffuse abnormalities. In controls, we observed the opposite, as older controls more often had EEG abnormalities than younger controls. Furthermore, APOE ε4 negative AD patients had more severe EEG abnormalities than APOE ε4 positive AD patients, while no such effect was observed in controls. There was no interaction between age at onset and APOE ε4 genotype.

CONCLUSION

Early onset and APOE ε4 negative AD patients present with more severe EEG abnormalities than late onset and APOE ε4 positive AD patients. These results suggest that in younger patients, AD manifests with more prominent functional brain changes.

New research criteria for the diagnosis of Alzheimer's disease applied in a memory clinic population

BACKGROUND

In the newly proposed research criteria for Alzheimer's disease (AD), patients are defined as having memory dysfunction in addition to either hippocampal atrophy or an abnormal cerebrospinal fluid (CSF) profile. This study applies the criteria in a memory clinic population, using clinical criteria as the reference criterion.

METHODS

138 AD patients, 145 nondemented subjects, 78 patients with other dementias and 91 patients with mild cognitive impairment (MCI) were included. Dichotomized medial temporal lobe atrophy (MTA) score on MRI and dichotomized CSF profiles (based on beta-amyloid1-42, tau and phosphorylated tau at threonine 181 levels) were used in combination with an episodic memory test to assess sensitivity, specificity and likelihood ratios (LR) of the newly proposed criteria and their components separately.

RESULTS

We found specificities of 95 and 49% for comparison with nondemented subjects and other demented patients, respectively, with a sensitivity of 86% for AD. Specificity was highest (100 and 77%, respectively, LR+ = 48) when both MTA score and CSF profile were abnormal in addition to the episodic memory test, at the cost of a low sensitivity (48%).

CONCLUSION

The newly proposed research criteria for AD yield a good specificity for comparison with nondemented subjects. When the type of dementia is clinically doubted, however, at least two supportive features should be considered (i.e. abnormal MTA score and CSF profile) in addition to memory impairment as core diagnostic criterion.

Diagnostic impact of CSF biomarkers in a local hospital memory clinic

BACKGROUND

CSF biomarkers amyloid-beta 1-42 (Abeta42), total tau (tau) and tau phosphorylated at threonine 181 (ptau-181) are useful diagnostic markers for Alzheimer's disease (AD). We examined the impact of these biomarkers in the diagnostic process in a non-academic memory clinic.

METHODS

One hundred and nine patients with available CSF were included from the local hospital memory clinic. Initially, patients were clinically diagnosed, and the clinician indicated their confidence in the diagnosis. Next the CSF results were presented, and the clinician re-evaluated his initial diagnosis. The main outcomes were changes in initial diagnosis and diagnostic confidence.

RESULTS

Forty-seven patients were initially diagnosed with AD, 26 were diagnosed with another type of dementia, 18 were diagnosed with mild cognitive impairment, and 18 received a non-dementia diagnosis. All biomarkers distinguished between AD and non-dementia (p < 0.01); tau and ptau-181 also distinguished AD from other types of dementia (p < 0.001). After CSF biomarker levels were revealed, 11 diagnoses changed. In 31% of the diagnoses, the clinician gained confidence, while in 10% confidence decreased.

CONCLUSION

We found that knowledge of CSF biomarker profiles changed the diagnosis in 10% of the cases, and confidence in the diagnosis increased for one third of the patients.

Joint effect of hypertension and APOE genotype on CSF biomarkers for Alzheimer's disease

We examined the impact of hypertension on cerebrospinal fluid (CSF) biomarkers amyloid-beta1-42 (Abeta42), total tau (tau), and phosphorylated tau at threonine 181 (ptau-181), and assessed the modifying role of APOE genotype in this relation in 546 patients (mean age 65 +/- 10, 47% female) from our memory-clinic. Of these patients 150 had subjective complaints, 140 were diagnosed with mild cognitive impairment, and 256 with Alzheimer's disease. Linear regression analyses adjusted for age, gender, and diagnosis showed that the association of hypertension with tau and ptau-181 was modified by APOE genotype (p-values for interaction p< 0.05). In APOE epsilon4 homozygotes (n=74), and to a lesser extent in APOE epsilon4 heterozygotes, hypertension was associated with higher tau and ptau-181 levels; beta (95%CI) were 188 (11; 364) pg/mL and 22 (3; 42) pg/mL for the APOE epsilon4 homozygotes. Hypertension was not associated with Abeta42 levels, and APOE genotype did not modify this relation. Our findings suggest that hypertension is directly related to tau pathology in APOE epsilon4 homozygous carriers.

Standardization of Assay Procedures for Analysis of the CSF Biomarkers Amyloid β((1-42)), Tau, and Phosphorylated Tau in Alzheimer's Disease: Report of an International Workshop

Large variation in assay performance and outcomes of CSF Aβ1-42, total Tau (Tau), and phosphorylated Tau (pTau) (at amino acid 181) levels is observed between laboratories. The aim of this study was to assess the differences in assay procedures between several experienced international laboratories, as potential sources of error. 14 groups performed the Aβ42, Tau, and pTau assays according to the guidelines of the manufacturer. Differences in analytical procedures between the laboratories were monitored. At least 23 items in assay procedures were identified that varied between the laboratories, including procedures for washing, pipetting, incubation, finishing, and sample handing. In general, the inter- and intra-assay variation between the groups was generally below 10% for all three assays. We concluded that 17 international centers that use the same assays for Aβ42, Tau and pTau on a regular basis do not uniformly adhere to the procedures recommended by the manufacturer. For harmonization of intercenter results of these biomarkers standardization of protocols is highly needed.

Batch prepared protein standards for cerebrospinal fluid (CSF) biomarkers for neurodegeneration

Immuno-assays are increasingly used for quantification of protein biomarkers for neurodegeneration. It has been proposed to use such cerebrospinal fluid (CSF) protein biomarkers as diagnostic tests for Alzheimer's disease. In two recent world-wide validation studies we found the analytical accuracy to be poor (inter-laboratory coefficient of variation, CV>10%) for CSF tau protein, CSF phospho-tau protein, CSF amyloid beta protein and the CSF neurofilament light chain protein. Retrospectively we suspected that the lack of preparation of accurate and consistent protein standards may have been one reason for the poor inter-laboratory CV. Here we confirm this hypothesis prospectively under standardised and optimised conditions. The CVs for CSF tau, CSF phospho-tau and CSF amyloid beta of individually prepared standards are 8%, 12% and 12% compared to significantly lower CVs for batch prepared standards (5%, 8%, 7%, respectively, p<0.05). This issue will need to be solved in order to ensure that the attempts to include these CSF protein biomarkers either as a diagnostic tool or a secondary outcome measure for treatment trials will be successful.

Additional value of CSF amyloid-beta 40 levels in the differentiation between FTLD and control subjects

To determine the additional value of cerebrospinal fluid (CSF)amyloid-beta1-40 (Abeta40) next to amyloid-beta1-42 (beta42), total tau (Tau), and tau phosphorylated at threonine-181 (pTau) to distinguish patients with frontotemporal lobar degeneration (FTLD), Alzheimer's disease (AD), and controls, we measured CSF levels of Abeta40, Abeta42, pTau, and Tau in 55 patients with FTLD, 60 with AD, and 40 control subjects. Logistic regression was used to identify biomarkers that best distinguished the groups. Additionally, a decision tree (cost=test method; Matlab 7.7) was used to predict diagnosis selecting the best set of biomarkers with the optimal cut-off. Logistic regression showed that Abeta42 and pTau CSF levels provided optimal distinction between AD and FTLD. A combination of Abeta42, Tau, and Abeta40 optimally discriminated FTLD from controls and AD from controls. The decision tree used Abeta42 (cut-off 578 pg/ml) to identify AD (positive predictive value (PPV) 97%), followed by Tau(cut-off 336 pg/ml) to identify FTLD (PPV 67%), and in the last step,Abeta40 (cut-off 10 ng/ml) was used to differentiate controls (PPV68%). Applying CSF Abeta40 levels in the model, the PPV of diagnosis increased to 75% as opposed to 70% when only Abeta42 and Tau were used. CSF Abeta40 levels added to the conventional CSF biomarkers increases the potential to discriminate subjects with dementia from controls. Our findings favor the implementation of CSF Abeta40 in differential diagnosis between FTLD, AD, and control subjects.

BACE1 activity in cerebrospinal fluid and its relation to markers of AD pathology

Several studies have shown that reduced amyloid-beta 1-42 (Abeta(42)) and increased tau levels in cerebrospinal fluid (CSF) reflect increased Alzheimer's disease (AD) pathology in the brain. beta-site APP cleaving enzyme (BACE1) is thought to be the major beta-secretase involved in Abeta production in the brain, and therefore we investigated the relation between BACE1 activity and CSF markers Abeta(40), Abeta(42), total tau (t-tau), and tau phosphorylated at threonine 181 (p-tau) in CSF of control (n=12), mild cognitive impairment (n=18), and AD (n=17) subjects. Patients were classified according to their Abeta(42), t-tau, and p-tau CSF biomarker levels, with either an AD-like biomarker profile (two or three biomarkers abnormal: Abeta(42) < 495 pg/ml in combination with t-tau > 356 pg/ml, and/or p-tau > 54 pg/ml) or a normal biomarker profile (<or= one biomarker abnormal). This resulted in 19 subjects with an AD-like biomarker profile (66 +/- 6 years, 53% female, and Mini-Mental Status Examination (MMSE) score: 23 +/- 5) and 28 subjects with a normal biomarker profile (62 +/- 11 years, 43% female, and MMSE score: 27 +/- 4). Subjects with an AD-like biomarker profile had higher CSF BACE1 activity levels, compared to patients with a normal biomarker profile (20 pg/ml and 16 pg/ml respectively; p=0.01), when controlled for age and gender. In the whole sample, BACE1 activity correlated with CSF levels of Abeta(40), t-tau, and p-tau (r=0.38, r=0.63, and r=0.65; all p< 0.05), but not with Abeta(42). These data suggest that increased BACE1 activity in CSF relates to AD pathology in the brain.

Differences in total human chorionic gonadotropin immunoassay analytical specificity and ability to measure human chorionic gonadotropin in gestational trophoblastic disease and germ cell tumors

OBJECTIVE

To determine the ability of several radioimmunoassays and commercial two-site immunoassays to detect the first World Health Organization International Reference Reagents (IRRs) for 6 defined human chorionic gonadotropin (hCG) variants and to compare their performance in measuring hCG in sera from patients with gestational trophoblastic disease (GTD) and germ cell tumors (GCTs) of the testis or ovary.

STUDY DESIGN

The reactivity of the different assays with the 6 IRRs together with the current fourth International Standard (IS, 75/589) was tested using 5 commercial two-site assays as well as 2 competitive polyclonal radioimmunoassays (RIAs) and a competitive monoclonal immunoassay. Individual samples from 41 patients (19 GCT and 22 GTD) with high circulating levels of hCG (range, 718-6,055,000 IU/L) were diluted and measured using the various immunoassays.

RESULTS

The results of 4 GCT patient samples varied markedly among the assays, including 1 sample that was grossly underestimated by 3 of the commercial assays.

CONCLUSION

Comparison of each assay's reactivity to the variant isoforms revealed that recognition of the isoforms was highly variable, particularly for hCGbeta and hCGbeta core fragment (hCGbetacf).

Serum testosterone levels measured by isotope dilution-liquid chromatography-tandem mass spectrometry in postmenopausal women versus those in women who underwent bilateral oophorectomy

BACKGROUND

Differentiation between subtle changes in low serum testosterone concentrations, common in women and children, is not possible with current commercially available assays. The objectives of the study were to develop a method based on stable isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with adequate sensitivity and specificity and to investigate the applicability of this assay in serum samples from pre- and postmenopausal women.

METHODS

For 16 women, testosterone levels were measured in blood samples drawn two years before and after physiological menopause, and for eight women in samples drawn before and after bilateral oophorectomy. Testosterone was extracted from serum, derivatized and analysed on an LC-MS/MS.

RESULTS

The developed ID-LC-MS/MS method allowed for specific and reproducible measurement of testosterone. Comparison with stable isotope dilution-gas chromatography coupled to mass spectrometry detection by Deming regression analysis gave a slope of 1.025 and an intercept of 0.055 nmol/L (r = 0.9998). A significant decrease was found in testosterone concentrations before and after bilateral oophorectomy (P = 0.02), whereas no significant difference was found before and after natural menopause (P = 0.4).

CONCLUSIONS

The ID-LC-MS/MS assay measures serum testosterone with acceptable accuracy and is useful in female samples, supporting the conclusion that the postmenopausal ovary contributes to circulating testosterone. To our knowledge, our analytical method compares favourably to similar published methods in terms of sensitivity. The sensitivity and specificity of this method comply with the reference method for measurement of testosterone in serum samples of women, children and men suffering from hypogonadism and can also be used for men with testosterone in the reference range.

The STOX1 genotype associated with pre-eclampsia leads to a reduction of trophoblast invasion by alpha-T-catenin upregulation

By using complementary in vitro and ex vivo approaches, we show that the risk allele (Y153H) of the pre-eclampsia susceptibility gene STOX1 negatively regulates trophoblast invasion by upregulation of the cell-cell adhesion protein alpha-T-catenin (CTNNA3). This is effectuated at the crucial epithelial-mesenchymal transition of proliferative into invasive extravillous trophoblast. This STOX1-CTNNA3 interaction is direct and includes Akt-mediated phosphorylated control of nucleo-cytoplasmic shuttling and ubiquitin-mediated degradation as shared with the FOX multigene family. This, to our knowledge, is the first time a genotype associated with pre-eclampsia has been shown to directly limit first trimester extravillous trophoblast invasion, the earliest hallmark of pre-eclampsia.

First trimester maternal serum ADAM12s levels in twin pregnancies

BACKGROUND

A disintegrin and metalloprotease 12s (ADAM12s) is a potential first trimester serum marker for fetal trisomy and adverse pregnancy outcome in singletons. In this study, ADAM12s levels in first trimester serum of uncomplicated and complicated twins were evaluated.

METHODS

ADAM12s was studied in maternal serum of 215 twin pregnancies, collected between 2004 and 2008. ADAM12s was measured 'blind to outcome' using AutoDelfia (PerkinElmer, Turku, Finland). As a reference, data from 2423 singletons were used.

RESULTS

The median ADAM12s level was increased in euploid twins [1.61 multiples of the median (MoM); n = 209] compared with singletons. The median ADAM12s MoM was significantly lower in monochorionic (1.36 MoM; n = 41) compared with dichorionic twins (1.67 MoM; n = 168) (Mann-Whitney U test, p = 0.005). Trisomy 21 was identified in two pregnancies. Median ADAM12s MoM in twins complicated by hypertensive disorders (1.77 MoM, n = 35) or small for gestational age fetus (1.54 MoM; n = 24) was not significantly different from uncomplicated twins (1.64 MoM; n = 134).

CONCLUSION

Median ADAM12s MoM in euploid twins was increased compared with singletons. Monochorionic had significantly lower median ADAM12s MoM than dichorionic twins. Median ADAM12s MoMs were not significantly different in twins complicated by hypertensive disorders or small for gestational age fetus compared with uncomplicated twins.

Frequency distribution of polymorphisms in the FSH receptor gene in infertility patients of different ethnicity

Studies on the frequency distribution of follicle-stimulating hormone receptor (FSHR) polymorphisms report conflicting results. It has been suggested that ethnicity might influence these outcomes. Therefore, the aim of this study was to determine the frequency distribution of FSHR polymorphisms at position 680 of exon 10 within a large group of women with fertility problems from different ethnic backgrounds. A total of 1771 women of different ethnic origin (Caucasian, Asian, Hindustani, Creole and Mediterranean) were studied. FSHR single-nucleotide polymorphisms at codon 680 of exon 10 were determined by restriction fragment length polymorphism of amplicons generated by polymerase chain reaction. Genotypes were compared with serum FSH concentrations and between different ethnic groups. A significantly lower number of Asians (10.5%) were found to have the Ser680Ser receptor variant compared with Caucasians (21.5%) and Mediterraneans (22.3%) (P=0.010). FSH concentrations did not differ between the various ethnic groups, or the different FSHR polymorphisms. In conclusion, the Ser680Ser receptor variant is less common in the Asian subgroup compared with Caucasians and Mediterraneans. This indicates that, when comparing allelic frequency distributions of the FSHR polymorphism variants, ethnic background should be accounted for. FSH concentrations did not differ between FSHR polymorphisms or between ethnic groups.

Amyloid-β(1–42), Total Tau, and Phosphorylated Tau as Cerebrospinal Fluid Biomarkers for the Diagnosis of Alzheimer Disease

Background: To improve ante mortem diagnostic accuracy of Alzheimer disease (AD), measurement of the biomarkers amyloid-β(1–42) (Aβ42), total tau (Tau), and tau phosphorylated at threonine181 (pTau) in cerebrospinal fluid (CSF) has been proposed. We have used these markers and evaluated their performance.

Methods: From January 2001 to January 2007, we assessed Aβ42, Tau, and pTau by commercial ELISAs in CSF from 248 consecutive AD patients and 131 patients with subjective memory complaints attending our outpatient memory clinic. Diagnoses were made blind to the results of the biomarker assays. We assessed sensitivity and specificity and analyzed trends over time.

Results: Interassay CVs from analysis of pools of surplus CSF specimens were mean 11.3% (SD 4.9%) for Aβ42; 9.3% (1.5%) for Tau, and 9.4% (2.5%) for pTau, respectively (n = 7–18). To achieve 85% sensitivity, cutoff values were 550 (95% CI 531–570) ng/L for Aβ42; 375 (325–405) ng/L for Tau, and 52 (48–56) ng/L for pTau. Corresponding specificities were 83% (95% CI 76%–89%) for Aβ42, 78% (70%–85%) for Tau, and 68% (60%–77%) for pTau. Logistic regression to investigate the simultaneous impact of the 3 CSF biomarkers on the diagnosis yielded a sensitivity of 93.5% and specificity of 82.7%, at a discrimination line of Aβ42 = 373 + 0.82 × Tau. The area under the ROC curves of Tau and pTau showed significant fluctuation over time.

Conclusions: CSF biomarkers Aβ42 and Tau can be used as a diagnostic aid in AD. pTau did not have additional value over these 2 markers. Cutoff values, sensitivities, specificities, and discrimination lines depend on the patient groups studied and laboratory experience.

ADAM12s as a first-trimester screening marker of trisomy

OBJECTIVE

To evaluate the potential of maternal serum A Disintegrin And Metalloprotease 12-S (ADAM12s) as an additional marker for the combined test in the Dutch first-trimester national Down syndrome (DS) screening program.

METHODS

Serum samples were collected between 2004 and 2007 as part of the national program. A total of 218 singleton cases of trisomy 21 (DS), 62 trisomy 18 (Edwards syndrome) and 29 trisomy 13 (Patau syndrome) were identified. All cases were matched with controls for gestation, maternal weight and maternal age. The serum concentration of ADAM12s was determined 'blind' to outcome and expressed in multiples of the gestation-specific median for controls (MoM).

RESULTS

The median ADAM12s was 1.00 MoM in controls and in the DS cases at 8, 9, 10, 11, 12, 13 weeks it was 0.45 (n = 3), 0.73 (22), 0.74 (53), 0.85 (37), 0.92 (71), 1.06 (32) MoM, respectively. The median for trisomy 18 was 0.85 MoM and for trisomy 13 0.63 MoM.

CONCLUSION

The ADAM12s MoM values were clearly reduced in early first-trimester for all trisomies. However, the screening performance for DS did not greatly improve adding ADAM12s. ADAM12s could be an additional biochemical marker for first-trimester screening for trisomies other than DS.