Relationship between apoE genotype and CSF beta-amyloid (1-42) and tau in patients with probable and definite Alzheimer's disease

We investigated the usefulness of cerebrospinal fluid (CSF) beta-amyloid42 (Abeta42), beta-amyloid40 (Abeta40) and tau analyses in the diagnosis of Alzheimer's disease (AD). The study included 41 definite AD cases, 80 patients with probable AD. 27 with other dementias and 39 neurological controls. Abeta42, Abeta340 and tau protein concentrations in CSF were measured of using ELISA assays. Abeta42 levels were decreased and tau increased in AD. Combination of Abeta42 and tau resulted a sensitivity of 50.4% for AD and specificities of 94.8% for controls and 85.2% for other dementias. Ninety-one percent of the patients with Abeta42 below the cutoff value (340 pg/ml) and tau above the cutoff value (380 pg/ml) had AD. AD patients carrying apoE epsilon4 allele had lower Abeta42 (P < 0.005) and higher tau (P < 0.05) levels than those without an E4 allele, and 18 (81.8%) of the 22 AD patients who had normal Abeta42 and tau levels were apoE e4 allele non-carriers. Low Abeta42 and high tau concentration in CSF strongly support the diagnosis of AD. Measurement of Abeta42 may help the early diagnosis of cases at risk for AD such as apoE E4 allele carriers.

Identification of a novel 4.6-kb genomic deletion in presenilin-1 gene which results in exclusion of exon 9 in a Finnish early onset Alzheimer's disease family: an Alu core sequence-stimulated recombination?

Mutations in the presenilin-1 (PS-1) gene have been shown to cause early onset Alzheimer's disease (EOAD) in an autosomal dominant manner. We have identified a novel 4.6-kb genomic deletion in the PS-1 gene in a Finnish EOAD family, which leads to an inframe exclusion of exon9 (delta9) from the mRNA transcript. This germline mutation results in a similar alteration in mRNA level as previously described with the variant AD and the delta9 splice-site mutations. In this present EOAD family, the clinical and neuropathological phenotype of patients are those of the typical AD without indications of spastic paraparesis or 'cotton wool' plaques, which are the hallmarks of the variant AD. A sequence analysis of the deletion crossover site of the mutant and corresponding wild type regions revealed complete homology with the recombigenic 26 bp Alu core sequence at intron 8. In addition, a segment at the intron 9 breakpoint displayed homology with the core sequence, but comparison of the 5' and 3' breakpoint sequences did not reveal significant identity favouring involvement of Alu core sequence-stimulated non-homologous recombination rather than Alu-mediated homologous pairing of the fragments. This study shows that large genomic rearrangements can affect the EOAD gene PS-1 through a mechanism, which may involve Alu core sequence-stimulated recombination.

Hippocampus in Alzheimer's disease: a 3-year follow-up MRI study

BACKGROUND

Due to the progressive nature of Alzheimer's disease (AD), it has been proposed that serial imaging studies tracking the course of progression might improve the diagnostic accuracy of AD.

METHODS

Longitudinal changes in hippocampal volumes were evaluated using magnetic resonance imaging (MRI) over a period of 3 years in 27 AD patients and 8 control subjects.

RESULTS

A statistically nonsignificant trend towards accelerated volume loss in the AD group compared to control subjects was observed. During the study period, the average shrinkage of the hippocampal volume ranged from -2.2% to -5.8% in control subjects, and from -2.3% to -15.6% in AD patients.

CONCLUSIONS

The observed changes at an individual level were small, and within the accuracy range of the measurements. Therefore, serial MRI of the hippocampus did not offer any advantage over a single MRI to support the diagnosis of AD in this study sample.

How does the apolipoprotein E genotype modulate the brain in aging and in Alzheimer's disease? A review of neuroimaging studies

The epsilon 4 allele of apolipoprotein E is a risk factor for Alzheimer's disease, but also a modulator of its clinical picture. In this paper, recent research in neuroimaging of aging and Alzheimer's disease in relation to apolipoprotein E is reviewed, emphasizing the advances but also the controversies. Further, the possible clinicopathological implications of these findings are discussed.

Insulin sensitivity and insulin secretion in monozygotic and dizygotic twins

AIMS/HYPOTHESIS

To estimate the heritability of insulin sensitivity and insulin secretion, both of which are considered to contribute to the development of Type II (non-insulin-dependent) diabetes mellitus.

METHODS

Intraclass correlation coefficients and heritability estimates for insulin sensitivity (euglycaemic clamp) as well as first-phase and late-phase insulin secretion (intravenous glucose tolerance test) were calculated in 21 monozygotic and 20 dizygotic twin pairs of the same sex between 54 and 72 years of age.

RESULTS

Intrapair correlations for all traits were consistently higher in monozygotic than in dizygotic pairs. Insulin secretion correlated significantly only between monozygotic (first-phase r = 0.55; p = 0.003 and late-phase r = 0.66; p < 0.001) twins giving heritability estimates of 0.55 and 0.58, respectively. Insulin-stimulated glucose uptake showed a more modest correlation between monozygotic twins (r = 0.46; p = 0.015). The heritability estimate was 0.37. The heritability estimate for waist-to-hip ratio was 0.76 in female and 0.70 in male twins.

CONCLUSION/INTERPRETATION

Genetic variability seems to contribute to the variance of insulin sensitivity as well as of insulin secretion. In the current study, genetic variance accounted almost 60% for the variance in glucose-stimulated insulin secretion and almost 40% for the variance in insulin-stimulated glucose uptake. Our data is also compatible with findings in monogenic forms of diabetes in which genetic defects in insulin secretion play a predominant part in the pathogenesis of hyperglycaemia.

Is the presenilin-1 E318G missense mutation a risk factor for Alzheimer's disease?

Nearly all of the presenilin-1 (PSEN-1) mutations are missense mutations leading to Alzheimer's disease (AD). The role of the mutation E318G (a substitution of glutamic acid to glycine) in the PSEN-1 is controversial. It has been found both in AD patients and in non-demented control individuals. Using the polymerase chain reaction and the restriction fragment length polymorphism method, we screened for E318G mutation in a total of 16 familial (FAD) cases, in 64 sporadic neuropathologically confirmed AD cases and in 270 non-demented controls including 35 neuropathologically confirmed individuals. We detected the E318G mutation in four FAD cases, seven sporadic AD cases and 10 control individuals with highly varying onset-ages. Odds ratios for carrying the mutation were 7.6 and 3 in FAD and sporadic AD cases, respectively. Our results suggest that this mutation could be a risk factor in the Finnish FAD and sporadic AD population. It may be in linkage disequilibrium with a pathogenic change somewhere else in the PSEN-1 gene or in close proximity to the PSEN-1 gene.

Candesartan Cilexetil, a Novel Angiotensin II Type 1 (AT1) Receptor Blocker, Reduces Microalbuminuria in Patients with Type II Diabetes Mellitus and Mild Hypertension

Microalbuminuria is a predictor of nephropathy in patients with type I or type II diabetes mellitus, and interventions that decrease albuminuria are likely to postpone the development of severe renal impairment. Suppression of the renin-angiotensin system by angiotensin-converting enzyme (ACE) inhibition has been effective in this respect. However, direct inhibition of the negative cardiovascular effects of angiotensin II by means of an angiotensin II type 1 (AT 1 ) receptor blocker would be expected to produce reductions in albuminuria similar to those produced by ACE inhibition. In this study, we assessed the effect of candesartan cilexetil on microalbuminuria in patients with type II diabetes mellitus and mild hypertension. The analysis was performed in a subset of patients ( n = 35) with microalbuminuria (10-100 mg in an overnight urine sample) at randomization in a large double-blind, placebo-controlled study. The subset was part of a study investigating the effect of candesartan cilexetil on blood glucose homeostasis and the blood lipid profile in patients with stable type II diabetes mellitus, mild hypertension (diastolic blood pressure 90-100 mmHg) and serum creatinine levels below 150 &#55 mol/l for men and below 120 &#119 mol/l for women. Patients were randomized, after a 4-week placebo run-in period, to 12 weeks of double-blind treatment with candesartan cilexetil, 8-16 mg ( n = 83), or placebo ( n = 78) once daily. After 12 weeks of treatment, candesartan cilexetil did not influence blood glucose homeostasis or the blood lipid profile compared with placebo. Body weight remained unchanged in both treatment groups. Median urinary albumin excretion decreased by 57%, from 28.5 to 12.2 mg/12 h, in patients treated with candesartan cilexetil ( n = 15), whereas it increased by 9%, from 30.2 to 32.8 mg/12 h, in the placebo group ( n = 20; p = 0.03 for the difference between treatments). The mean reduction in diastolic blood pressure was 6.4 mmHg in the group given candesartan cilexetil and 3.6 mmHg in the group given placebo. In conclusion, 12 weeks of treatment with the AT 1 -receptor antagonist candesartan cilexetil reduced microalbuminuria in patients with stable type II diabetes mellitus and mild hypertension. Thus, candesartan cilexetil appears to have the potential for renal protection in this patient category.

A longitudinal quantitative EEG study of Alzheimer's disease: relation to apolipoprotein E polymorphism

Apolipoprotein E (apoE) sigma4 allele is a risk factor for late-onset Alzheimer's disease (AD) and is proposed to have an impact on cholinergic function in AD. Slowing of the EEG is characteristic in AD and the cholinergic system has an important role in modulating EEG. QEEG was recorded from 31 AD patients at the early stage of the disease and after a 3-year follow-up. AD patients were divided into subgroups according to the apoE sigma4 allele (2sigma4, 1sigma4 and 0sigma4). AD subgroups did not differ in clinical severity or duration of dementia. The AD patients carrying the sigma4 allele had more pronounced slow-wave activity than AD patients without the sigma4 allele, although the progression rate did not change. The differences in EEG may suggest differences in the degree of the cholinergic deficit in these subgroups.

Heritability of albumin excretion rate in families of patients with Type II diabetes

AIMS/HYPOTHESIS

To study whether albumin excretion rate is an inherited trait in families of patients with Type II (non-insulin-dependent) diabetes mellitus.

METHODS

We used three different approaches. Heritability of albumin excretion rate was studied in 267 nuclear families from the Botnia Study in Western Finland using parent-offspring regression. Albumin excretion rate was also measured in 206 non-diabetic offspring of 119 Type II diabetic parents with or without albuminuria (albumin excretion rate > 20 microg/min). Finally, albumin excretion rate was measured in altogether 652 siblings of 74 microalbuminuric and 320 normoalbuminuric probands. To study the potential confounding effect of blood pressure, the heritability of blood pressure was estimated in 718 nuclear families.

RESULTS

Using parent-offspring regression, the heritability of albumin excretion rate was about 30 %, being the strongest from mothers to sons (35-39 % resemblance). The heritability for systolic blood pressure ranged from 10 to 20 % and for diastolic blood pressure from 10 to 27 %. Offspring of albuminuric Type II diabetic parents had higher albumin excretion rates (median 5.4 [range 1.0-195] vs 4.0 [1.0-23] microg/min, p = 0. 0001) and a higher frequency of microalbuminuria (11 vs 2 %, p = 0. 012) than offspring of normoalbuminuric parents. Further, siblings of microalbuminuric probands had higher albumin excretion rates than siblings of normoalbuminuric probands (4.1 [0.6-14.5] vs 3.6 [0.2-14. 4] microg/min, p < 0.01).

CONCLUSION/INTERPRETATION

The data suggest that albumin excretion rate is an inherited trait in families of patients with Type II diabetes. [Diabetologia (1999) 42: 1359-1366]

Serum and follicular fluid leptin during in vitro fertilization: relationship among leptin increase, body fat mass, and reduced ovarian response

The satiety factor leptin is expressed in several reproductive tissues, but its role in the control of reproductive physiology is not well understood. We studied leptin concentrations in the sera and follicle fluids of 52 women [body fat mass percentage (BFM%) range, 19.6-38.8%] undergoing pituitary down-regulation and ovarian hyperstimulation for in vitro fertilization (IVF) treatment. Fasting serum samples were collected 1) at maximal suppression before the initiation of gonadotropin treatment, 2) at maximal ovarian hyperstimulation, 3) at the time of oocyte retrieval, and 4) 16 days later when all subjects were under exogenous luteal support using 600 mg progesterone daily. Follicular fluid (FF) was obtained at oocyte retrieval from two representative preovulatory follicles in both ovaries. During ovarian hyperstimulation there was a significant 60% increase in serum leptin concentrations from 10.9 +/- 1.1 (SEM) to 15.7 +/- 1.5 ng/mL (P < 0.01) between suppression and maximal hyperstimulation, demonstrating that the ovarian functional state can affect serum leptin concentrations. A serum leptin increase of 22-198% during ovarian hyperstimulation was evident in 43 subjects, whereas in 9, leptin concentrations remained unchanged. A positive correlation between leptin change and BFM% (r = 0.55; P < 0.0005) was observed in the 43 leptin responders. The follicular fluid leptin level was similar to that in serum. In separate linear regression analysis, BFM% contributed to 59-64%, body mass index to 46-56%, and weight to 46-55% (all P < 0.001) of the variability in leptin concentrations at the 4 time points. The 20-fold increase in serum estradiol concentrations during IVF was not significantly correlated with changes in leptin concentrations. On the contrary, the relative serum leptin increase was negatively associated with the ovarian response to hyperstimulation, as revealed by the numbers of follicles (b = -0.28; r2 = 8.1%; P < 0.05) and oocytes retrieved (b = -0.39; r2 = 15.2%; P < 0.01). This relationship was further reflected in a positive correlation between the percent increases in leptin and FSH concentrations (r = 0.39; P < 0.01). The significant relationship of high leptin and reduced ovarian response was also maintained when the cumulative dose of FSH was used as a covariable. Reduced ovarian response was not a function of body mass index, BFM%, basal leptin levels, or insulin concentrations. Fasting serum insulin concentrations remained unchanged in response to IVF, but were positively correlated to serum leptin concentrations at all four time points. Our data suggest that leptin production may be influenced by the ovarian functional state. During IVF a high relative leptin increase is associated with adiposity and a reduced ovarian response. These observations support the possibility that high leptin concentrations might reduce ovarian responsiveness to gonadotropins. Hence, leptin might explain in part why obese individuals require higher amounts of gonadotropins than lean subjects to achieve ovarian hyperstimulation.

Linkage disequilibrium in the 13q12 region in Finnish late onset Alzheimer's disease patients

Alzheimer's disease (AD) is a complex neurodegenerative disorder, for which several disease-associated loci have been located on different chromosomes. We have used a population-based linkage disequilibrium mapping approach in order to find potential AD-associated loci on chromosome 13. To avoid population stratification, late onset AD patients and age-matched controls were carefully chosen from the same geographical area in Eastern Finland, where the population is mainly descended from a small group of original founders. During the initial screening with chromosome 13-specific microsatellite markers, tetranucleotide marker D13S787 was found to be in linkage disequilibrium in the 13q12 region. Screening this region with additional microsatellite markers revealed that marker D13S292 was also significantly associated with AD. Stratification of the AD patients and controls into groups according to apolipoprotein E, sex, and familial/sporadic status indicated that the 13q12 locus was associated with female familial AD patients regardless of ApoE genotype. Based on the physical data from the region 13q12, markers D13S292 and D13S787 were estimated to reside in a 810kb long YAC clone 754h7 together with two infant brain-derived ESTs and the H,K-ATPase alpha-subunit protein gene (ATP1AL1). The localisation of these sequences at the linkage disequilibrium region suggests that they may be candidate genes involved in a sex-specific effect during development of AD.

Promoter polymorphism (-491A/T) in the APOE gene of Finnish Alzheimer's disease patients and control individuals

Apolipoprotein E (APOE) epsilon4 allele is a major risk factor for the development of Alzheimer's disease (AD). It has been suggested that the quantitative expression of APOE alleles results from mutations in the promoter region of this gene. We studied the -491A/T promoter polymorphism and whether it is dependent on the APOE epsilon4 allele in clinic-based AD (n = 106) and community-based control (n = 123) samples. The -491A/T and APOE polymorphisms were analyzed using the polymerase chain reaction method and restriction fragment length polymorphism analysis. The APOE epsilon4 allele was strongly associated with AD when compared with controls, P < 0.001 (odds ratio 5.85, 95% CI 3.29- 10. 41). The genotype distribution of the -491A/T polymorphism did not significantly differ between the study groups (P = 0.063), and the -491A allele was not associated with any significant risk in the AD group when compared to controls (odds ratio 1.82, 95% CI 0.95-3.49). However, haplotype estimation analysis indicated linkage disequilibrium between APOE -491A/T polymorphism and the APOE epsilon4 allele. Our findings confirm APOE polymorphism still to be the most efficient predictor of risk in AD.

Insulin-regulated mitochondrial gene expression is associated with glucose flux in human skeletal muscle

To identify abnormally expressed genes contributing to muscle insulin resistance in type 2 diabetes, we screened the mRNA populations from normal and diabetic human skeletal muscle using cDNA differential display and isolated abnormally expressed cDNA clones of mitochondrial-encoded NADH dehydrogenase 1 (ND1), cytochrome oxidase 1, tRNA(leu), and displacement loop. We then measured mRNA expression of these mitochondrial genes using a relative quantitative polymerase chain reaction method in biopsies taken before and after an insulin clamp in 12 monozygotic twin pairs discordant for type 2 diabetes and 12 matched control subjects and in muscle biopsies taken after an insulin clamp from 13 subjects with type 2 diabetes, 15 subjects with impaired glucose tolerance, and 14 subjects with normal glucose tolerance. Insulin infusion increased mRNA expression of ND1 from 1.02 +/- 0.04 to 2.55 +/- 0.30 relative units (P < 0.001) and of cytochrome oxidase 1 from 0.80 +/- 0.01 to 1.24 +/- 0.10 relative units (P < 0.001). The ND1 response to insulin correlated with glucose uptake (r = 0.46, P = 0.002). Although the rate of insulin-mediated glucose uptake was decreased in the diabetic versus the nondiabetic twins (5.2 +/- 0.7 vs. 8.5 +/- 0.8 mg x kg(-1) fat-free mass x min(-1), P < 0.01), insulin-stimulated ND1 expression was not significantly different between them (2.4 +/- 0.5 vs. 2.7 +/- 0.5 relative units). Neither was there any significant intrapair correlation of ND1 expression between the monozygotic twins (r = -0.15, NS). We conclude that insulin upregulates mitochondrial-encoded gene expression in skeletal muscle. Given the positive correlation between ND1 expression and glucose uptake and the lack of intrapair correlation between monozygotic twins, mitochondrial gene expression may represent an adaptation to intracellular glucose flux rather than an inherited trait.

Functional consequences of amyloidosis mutation for gelsolin polypeptide -- analysis of gelsolin-actin interaction and gelsolin processing in gelsolin knock-out fibroblasts

Gelsolin, an actin-modulating protein, derived from a single gene exists in intracellular and secreted forms. A point mutation at position 187 of both forms of gelsolin causes familial amyloidosis of the Finnish type (FAF). Here, we expressed both isoforms of the wild-type and FAF mutant gelsolin in mouse embryonic gelsolin-null fibroblasts. We demonstrate that the FAF mutation does not interfere with the normal actin-modulating function of intracellular gelsolin, and that aberrant processing of secreted FAF gelsolin to FAF amyloid precursor takes place in the gelsolin-negative background. These results suggest that, in patients with FAF, symptoms are caused by the accumulation in their tissues of amyloid derived from plasma gelsolin and are not due to functional differences in cytoplasmic gelsolin.

Defective intracellular transport of CLN3 is the molecular basis of Batten disease (JNCL)

Batten disease [juvenile-onset neuronal ceroid lipofuscinosis (JNCL)], the most common progressive encephalopathy of childhood, is caused by mutations in a novel lysosomal membrane protein (CLN3) with unknown function. In this study, we have confirmed the lysosomal localization of the CLN3 protein by immunoelectron microscopy by co-localizing it with soluble and membrane-associated lysosomal proteins. We have analysed the intracellular processing and localization of two mutants, 461-677del, which is present in 85% of CLN3 alleles and causes the classical JNCL, and E295K [corrected], which is a rare missense mutation associated with an atypical form of JNCL. Pulse-chase labelling and immunoprecipitation of the two mutant proteins in COS-1-cells indicated that 461-677del is synthesized as an approximately 24 kDa truncated polypeptide, whereas the maturation of E295K [corrected] resembles that of the wild-type CLN3 polypeptide. Transient expression of the two mutants in BHK cells showed that 461-677del is retained in the endoplasmic reticulum, whereas E295K [corrected] was capable of reaching the lysosomal compartment. The CLN3 polypeptides were expressed further in mouse primary neurons where the wild-type CLN3 protein was localized both in the cell soma and in neuronal extensions, whereas the 461-677del mutant was arrested in the cell soma. Interestingly, co-localization of the wild-type CLN3 and E295K [corrected] proteins with a synaptic vesicle marker indicates that the CLN3 protein might participate in synaptic vesicle transport/transmission. The data presented here provide clear evidence for a cellular distinction between classical and atypical forms of Batten disease both in neural and non-neural cells.

Estimation of blood flow heterogeneity in human skeletal muscle using intravascular tracer data: importance for modeling transcapillary exchange

Distributed models of blood-tissue exchange are widely used to measure kinetic events of various solutes from multiple tracer dilution experiments. Their use requires, however, a careful description of blood flow heterogeneity along the capillary bed. Since they have mostly been applied in animal studies, direct measurement of the heterogeneity distribution was possible, e.g., with the invasive microsphere method. Here we apply distributed modeling to a dual tracer experiment in humans, performed using an intravascular (indocyanine green dye, subject to distribution along the vascular tree and confined to the capillary bed) and an extracellular ([3H]-D-mannitol, tracing passive transcapillary transfer across the capillary membrane in the interstitial fluid) tracer. The goal is to measure relevant parameters of transcapillary exchange in human skeletal muscle. We show that assuming an accurate description of blood flow heterogeneity is crucial for modeling, and in particular that assuming for skeletal muscle the well-studied cardiac muscle blood flow heterogeneity is inappropriate. The same reason prevents the use of the common method of estimating the input function of the distributed model via deconvolution, which assumes a known blood flow heterogeneity, either defined from literature or measured, when possible. We present a novel approach for the estimation of blood flow heterogeneity in each individual from the intravascular tracer data. When this newly estimated blood flow heterogeneity is used, a more satisfactory model fit is obtained and it is possible to reliably measure parameters of capillary membrane permeability-surface product and interstitial fluid volume describing transcapillary transfer in vivo.

Major decrease in the volume of the entorhinal cortex in patients with Alzheimer's disease carrying the apolipoprotein E epsilon4 allele

OBJECTIVE

Recent evidence indicates that the apolipoprotein E (ApoE) epsilon4 allele is a risk factor for developing Alzheimer's disease. It has also been proposed that it is associated with increased counts of amyloid plaques and neurofibrillary tangles that in turn are neuropathological hallmarks initially appearing in the medial temporal lobe structures in Alzheimer's disease. In this study, the effect of the ApoE epsilon4 allele on the volume of the entorhinal cortex was evaluated in vivo.

METHODS

The volume of the entorhinal cortex was measured on MR images using a recently designed histology based protocol in 16 patients with Alzheimer's disease with ApoE epsilon4 (mean age 70.4 (SD 9.9)), 11 patients with Alzheimer's disease without ApoE epsilon4 (mean age 69.1 (SD7.1)), and in 31 healthy age and sex matched normal controls (72.2 (SD 3.9)). The patients met the NINCDS-ADRDA criteria for probable Alzheimer's disease and were in mild to moderate stages of the disease. MRI was performed with a 1.5 Tesla Magnetom and a 3D technique permitting the reconstruction of 2.0 mm thick contiguous slices perpendicular to the axis of the anterior-posterior commissure.

RESULTS

The patients with Alzheimer's disease without the ApoE epsilon4 allele had atrophy in the entorhinal cortex, the volume was reduced by 27% compared with control subjects. However, the most prominent shrinkage (45%) in the entorhinal cortex was seen in patients with Alzheimer's disease with the ApoE epsilon4 allele (p=0.0001). The effect of epsilon4 on the entorhinal cortex volume was especially prominent in female patients with Alzheimer's disease compared to male patients with Alzheimer's disease (p=0.014). Additionally, patients with the ApoE epsilon4 allele had inferior performance in verbal and visual memory functions than those without the allele

CONCLUSIONS

Volumetric MRI measurements disclose that ApoE epsilon4 is associated with the degree of atrophy in the entorhinal cortex in early Alzheimer's disease, this effect being especially prominent in female patients with Alzheimer's disease.

Butyrylcholinesterase K variant and apolipoprotein E4 genes do not act in synergy in Finnish late-onset Alzheimer's disease patients

Examination of the allelic frequency of the butyrylcholinesterase K (BChE-K) variant gene revealed no increase among Finnish late-onset Alzheimer's disease (AD) patients either as a whole or among a subset of AD patients carrying the epsilon4 allele of apolipoprotein E (ApoE4). In contrast, BChE-K allele frequency was significantly reduced in the Finnish AD patient group under 75 years of age carrying the ApoE4 allele when compared to the non-demented controls (chi2, P < 0.05). The proportion of subjects with both BChE-K and ApoE4 alleles was 14% and 41% in AD and control groups, respectively (chi2, P < 0.01; odds-ratio 0.22, 95% CI 0.07-0.71). These results are in contrast to a previous study on English AD patients, in which the genes for BChE-K and ApoE4 were suggested to act in synergy.

Longitudinal SPECT study in Alzheimer's disease: relation to apolipoprotein E polymorphism

OBJECTIVES

In mild Alzheimer's disease, SPECT imaging of regional cerebral blood flow has highlighted deficits in the posterior association cortex, and later in the disease process, the deficit spreads to involve the frontal cortex. The sigma4 allele of apolipoprotein E is a risk factor for Alzheimer's disease. The effect of apolipoprotein E polymorphism on cerebral perfusion was studied. The hypothesis was that those patients with Alzheimer's disease who carry the sigma4 allele would have more severe cerebral hypoperfusion.

METHODS

Thirty one patients with Alzheimer's disease and eight age and sex matched control subjects were examined in a three year longitudinal study. Patients with Alzheimer's disease were divided into subgroups according to their number of sigma4 alleles. Regional cerebral blood flow ratios referred to the cerebellum were examined by 99mTc-HMPAO SPECT. Apolipoprotein E genotypes were determined by digestion of polymerase chain reaction products with the restriction enzyme Hha1.

RESULTS

All patients with Alzheimer's disease had bilateral temporoparietal hypoperfusion compared with control subjects. The two sigma4 allele subgroups had the lowest ratios at the baseline assessment in the parietal and occipital cortices, and at the follow up in the temporal, parietal, and occipital cortices. They had the highest reduction in percentage terms in the temporal and occipital cortices compared with the other subgroups. However, the global clinical severity did not differ at the baseline or follow up examinations between the subgroups.

CONCLUSION

Apolipoprotein E polymorphism is involved in the pathogenesis and heterogeneity of Alzheimer's disease as the most severe cerebral hypoperfusion was found in the sigma4 allele subgroups. This might have implications for therapeutic approaches in Alzheimer's disease.

Antihypertensive treatment with candesartan cilexetil does not affect glucose homeostasis or serum lipid profile in patients with mild hypertension and type II diabetes

This multicentre, randomized, controlled clinical trial assessed the effects of candesartan cilexetil (cand.cil.), a novel angiotensin II antagonist selective for the AT1 receptor with long-lasting antihypertensive activity, compared to placebo on glucose homeostasis and serum lipid profile in mild hypertensives with type II diabetes. A total of 161 men and women, 30-75 years old, with mild hypertension (sitting diastolic blood pressure 90-100 mmHg) and type II diabetes (HbA1c 5.5-9.0%), both measured after a 4-week placebo run-in period, were randomized to double-blind treatment with cand.cil. 8 mg o.i.d. (n = 83) or placebo (n = 78). Dose was increased to 16 mg o.i.d. if diastolic blood pressure remained >90 mmHg. At randomization and after 12 weeks of treatment HbA1c (primary effect variable), blood glucose and the serum lipid profile (including total cholesterol, HDL and LDL cholesterol, triglycerides) were assessed. The statistical analysis of the differences between treatments was based on changes from randomization to the end of the study. Cand.cil. had no significant effect on HbA1c, blood glucose and serum lipids compared to placebo. The median HbA1c both at baseline and after 12 weeks was 7.1% in patients on cand.cil., and 7.2% and 7.1% in patients on placebo. The 95% confidence interval for the median difference in change between the groups was narrow (-0.25; 0.16), including zero, which excluded any clinically important difference. The same held true for blood glucose (-1.10; 0.20), total cholesterol (-0.40; 0.20) and the other lipid parameters. More than 60% of the patients reached a diastolic blood pressure <90 mmHg; adverse events and withdrawals were similar in both groups. Thus, in patients with mild hypertension and type II diabetes, cand.cil. 8-16 mg o.i.d. for 12 weeks does not affect glucose homeostasis and serum lipids. Blood pressure was controlled in most patients, and cand.cil. was well tolerated.

CSF tau is related to apolipoprotein E genotype in early Alzheimer's disease

We quantified microtubule-associated protein tau in CSF (CSF tau) using ELISA assay in 168 subjects: 81 patients with clinically diagnosed early Alzheimer's disease (AD), 43 patients with other dementia, 11 Down's syndrome patients, and 33 nondemented neurologic control subjects. Multivariate ANOVA showed an effect of diagnostic group (p < 0.01) and apolipoprotein E (apoE) allele (p < 0.005) on CSF tau. Comparison between diagnostic groups showed higher CSF tau levels in AD than in the control group (p < 0.001). However, CSF tau values in the non-AD dementia group did not differ significantly from those of AD patients or neurologic control subjects. Tau levels were increased (p < 0.005) in AD patients with apolipoprotein E epsilon4 allele, a well-characterized risk factor of AD, compared with AD patients without epsilon4 allele, and the highest values were found in AD patients with two epsilon4 alleles. These increased levels of CSF tau may indicate pronounced neuronal degeneration and neurofibrillar pathology at the early stage of AD in patients carrying the epsilon4 allele. This study shows that the current ELISA test for CSF tau is not sensitive and specific enough to distinguish early AD from other dementias and indicates that in the interpretation of CSF tau analysis as a diagnostic tool, the apoE genotype should also be taken into account.

Volumes of the entorhinal and perirhinal cortices in Alzheimer's disease

We measured the volumes of the entorhinal, perirhinal, and temporopolar cortices on magnetic resonance images by using a recently designed histology-based protocol in 30 patients with early Alzheimer's disease (AD) and 32 healthy control subjects. Compared to the controls, all of these cortical regions were significantly atrophied in AD patients (p < 0.0001). However, the entorhinal cortex was the most severely involved brain region studied, with 40% volume loss, and this region provided the highest discriminative accuracy (92%) in separating patients with AD from healthy control subjects. Importantly, the entorhinal volume loss was evident already in mild AD. In addition, the volume of the entorhinal cortex was not dependent on age, but it did correlate significantly with the severity of the disease. Because it assesses the major site of initial neuropathological changes in AD, magnetic resonance imaging volumetric measurement of the entorhinal cortex can offer a tool for distinguishing AD patients even in the very early stages of the disease from healthy aged subjects.

MRI of the hippocampus in Alzheimer's disease: sensitivity, specificity, and analysis of the incorrectly classified subjects

In this study, magnetic resonance imaging (MRI) of the hippocampus for the diagnosis of early Alzheimer's disease (AD) is evaluated. We measured hippocampal volumes and the area of the medial hippocampus with a 1.5 T MR imager in 160 subjects: 55 patients with probable AD according to the NINCDS-ADRDA criteria, 43 subjects fulfilling the NIMH criteria of age-associated memory impairment (AAMI), 42 cognitively normal elderly controls, and 20 controls younger than 50 years. Three methods for normalization were compared. The hippocampi were atrophied in the AD patients, but not in the AAMI subjects or the elderly controls. There was no significant correlation between hippocampal volumes and age in the nondemented subjects. The discrimination based on volumetry resulted in an overall correct classification of 92% of AD patients vs. nondemented elderly subjects, whereas discrimination based on hippocampal area was less accurate, producing a correct classification in 80% of the subjects. We conclude that the hippocampus as assessed by MRI volumetry is atrophied early in AD, and spared by aging or AAMI. A brief critical review of previous studies is in concordance with the presented data: all the previous studies that have used volumetry, have similarly ended up with a good classification, whereas simpler or subjective measurements, subject to various sources of bias, have produced most variable results.

The level of cerebrospinal fluid tau correlates with neurofibrillary tangles in Alzheimer's disease

We measured tau concentrations in cerebrospinal fluid (CSF) samples taken during the lifetime of 43 patients with Alzheimer's disease (AD) and correlated these values with neurofibrillary tangle (NFT) scores as well as glial fibrillary acidic protein (GFAP) expression as a marker of astrocytosis in the brain post-mortem. The CSF tau values showed a positive correlation with neocortical NFT scores (r = 0.44, p < 0.005), while GFAP immmunoreactivity did not correlate with CSF tau. This study reveals a high variation in CSF tau values in patients with neuropathologically confirmed AD (range 194-1539 pg/ml) and indicates that high CSF tau values in the late phase of Alzheimer's disease predict severe neurodegeneration as evidenced by increased NFT scores.