Development of a nutrition knowledge questionnaire for young endurance athletes and their coaches

Both athletes and coaches should have adequate nutrition knowledge to understand the importance of diet on athletic performance, recovery, and health. Nutrition knowledge can be assessed reliably only by validated knowledge questionnaires. The aim of this study was to develop a reliable and valid questionnaire for assessing the nutrition knowledge of young endurance athletes and their coaches. The questionnaire was developed with an expert panel and pilot tested by athletes, coaches, and students. Content, face, and construct validities both as test-retest reliability and internal consistency reliability were ensured when the current questionnaire was developed. Athletes (n = 16) and coaches (n = 13) pilot tested the 127-item questionnaire. After item analysis and proposals from the expert panel, 41 items were removed. Internal consistency of the 86-item questionnaire in the pilot study was 0.87, measured using Cronbach's α. Construct validity was evaluated by the difference in knowledge between nutrition (n = 20) and humanities students (n = 22). Nutrition students had significantly higher knowledge scores (P < .001). Test-retest reliability for all knowledge sections between those groups was 0.85 measured using Pearson's r. Final adjustments to the questionnaire were made on the grounds of feedback from the respondents and proposals from the experts (n = 6). These adjustments resulted in minor changes in the construct of the items, the layout of the questionnaire, and the removal of 7 items. The final questionnaire had 79 items. The questionnaire can be used to measure the overall nutrition knowledge of endurance athletes and their coaches and to find potential gaps in nutrition knowledge.

Heritability and familiality of type 2 diabetes and related quantitative traits in the Botnia Study

AIMS/HYPOTHESIS

To study the heritability and familiality of type 2 diabetes and related quantitative traits in families from the Botnia Study in Finland.

METHODS

Heritability estimates for type 2 diabetes adjusted for sex, age and BMI are provided for different age groups of type 2 diabetes and for 34 clinical and metabolic traits in 5,810 individuals from 942 families using a variance component model (SOLAR). In addition, family means of these traits and their distribution across families are calculated.

RESULTS

The strongest heritability for type 2 diabetes was seen in patients with age at onset 35-60 years (h (2) = 0.69). However, including patients with onset up to 75 years dropped the h (2) estimates to 0.31. Among quantitative traits, the highest h (2) estimates in all individuals and in non-diabetic individuals were seen for lean body mass (h (2) = 0.53-0.65), HDL-cholesterol (0.52-0.61) and suppression of NEFA during OGTT (0.63-0.76) followed by measures of insulin secretion (insulinogenic index [IG(30)] = 0.41-0.50) and insulin action (insulin sensitivity index [ISI] = 0.37-0.40). In contrast, physical activity showed rather low heritability (0.16-0.18), whereas smoking showed strong heritability (0.57-0.59). Family means of these traits differed two- to fivefold between families belonging to the lowest and highest quartile of the trait (p < 0.00001).

CONCLUSIONS/INTERPRETATION

To detect stronger genetic effects in type 2 diabetes, it seems reasonable to restrict inclusion of patients to those with age at onset 35-60 years. Sequencing of families with extreme quantitative traits could be an important next step in the dissection of the genetics of type 2 diabetes.

Leisure-time physical activity and type 2 diabetes during a 28 year follow-up in twins

AIMS/HYPOTHESIS

The study aimed to investigate whether baseline physical activity protects against the occurrence of type 2 diabetes during a 28 year follow-up, after controlling for childhood environment and genetic predisposition.

METHODS

At baseline in 1975 same-sex twin pairs born in Finland before 1958 were sent a questionnaire including questions on physical activity. The participants (20,487 individuals, including 8,182 complete twin pairs) were divided into quintiles by leisure-time physical activity metabolic equivalent (MET) index (MET h/day). Type 2 diabetes was determined from nationwide registers for the follow-up period (1 January 1976-31 December 2004). Individual and pairwise Cox proportional hazard models were used.

RESULTS

During follow-up, 1,082 type 2 diabetes cases were observed. Among all individuals, participants in MET quintiles (Q) III-V had significantly decreased risk for type 2 diabetes compared with sedentary individuals (QI). The pairwise analysis on pairs discordant for physical activity showed that participants in MET QII to V had significantly lower hazard ratios (0.61, 0.59, 0.61, 0.61) compared with sedentary participants. These findings from the pairwise analysis persisted after adjusting for BMI. In the pairwise analysis, the BMI-adjusted hazard ratio for type 2 diabetes was lower for physically active members of twin pairs (combined QII-V) than for inactive co-twins (HR 0.54; 95% CI 0.37-0.78). Similar results were obtained for both dizygotic and monozygotic pairs, as well as for the subgroup of twin pairs defined as free of co-morbidities in 1981 (HR 0.36; 95% CI 0.17-0.76).

CONCLUSIONS/INTERPRETATION

Leisure-time physical activity protects from type 2 diabetes after taking familial and genetic effects into account.

Evidence that BMI and type 2 diabetes share only a minor fraction of genetic variance: a follow-up study of 23,585 monozygotic and dizygotic twins from the Finnish Twin Cohort Study

AIMS/HYPOTHESIS

We investigated whether BMI predicts type 2 diabetes in twins and to what extent that is explained by common genetic factors.

METHODS

This was a population-based twin cohort study. Monozygotic (n = 4,076) and dizygotic (n = 9,109) non-diabetic twin pairs born before 1958 answered a questionnaire in 1975, from which BMI was obtained. Information on incident cases of diabetes was obtained by linkage to nationwide registers until 2005.

RESULTS

Altogether, 1,332 twins (6.3% of men, 5.1% of women) developed type 2 diabetes. The HR for type 2 diabetes increased monotonically with a mean of 1.22 (95% CI 1.20-1.24) per BMI unit and of 1.97 (95% CI 1.87-2.08) per SD of BMI. The HRs for lean, overweight, obese and morbidly obese participants were 0.59, 2.96, 6.80 and 13.64 as compared with normal weight participants. Model heritability estimates for bivariate variance due to an additive genetic component and non-shared environmental component were 75% (men) and 71% (women) for BMI, and 73% and 64%, respectively for type 2 diabetes. The correlations between genetic variance components (r (g)) indicated that one fifth of the covariance of BMI and type 2 diabetes was due to shared genetic influences. Although the mean monozygotic concordance for type 2 diabetes was approximately twice the dizygotic one, age of onset of diabetes within twin pair members varied greatly, irrespective of zygosity.

CONCLUSIONS/INTERPRETATION

A 28-year follow-up of adult Finnish twins showed that despite high trait heritability estimates, only a fraction of covariation in BMI and incident type 2 diabetes was of genetic origin.

Long-term beneficial effects of glipizide treatment on glucose tolerance in subjects with impaired glucose tolerance

AIMS

To assess the efficacy and long-term effects of glipizide treatment on glucose and insulin metabolism in individuals with impaired glucose tolerance (IGT).

METHODS

Thirty-seven first-degree relatives of patients with type 2 diabetes fulfilling WHO criteria for IGT were randomized to treatment with either glipizide 2.5 mg once daily or matching placebo for 6 months. A 75 g, 2-h oral (OGTT) and 60 min intravenous glucose tolerance test (IVGTT) were performed at baseline and after 6 months. The subjects were followed up for another 12 months after discontinuation of treatment and a repeat OGTT was performed at 18 months.

RESULTS

Thirty-three subjects fulfilled the study. Markers of insulin sensitivity - i.e. fasting insulin and HOMA(IR)-index - improved in the glipizide group (P = 0.04 and 0.02 respectively) as well as HDL cholesterol (P = 0.05) compared with placebo group after 6 months. At 18 months, both fasting and 2 h glucose concentrations were significantly lower in the glipizide group compared with the placebo group (P = 0.04 and 0.03 respectively). The prevalence of type 2 diabetes was 29.4% in the placebo group and 5.9% in the glipizide group at 18 months. This equals an 80% relative risk reduction in the active treatment group.

CONCLUSIONS

Short-term treatment with glipizide improves glucose and insulin metabolism in subjects with IGT primarily by improving insulin sensitivity mediated by lowering glucose toxicity, thereby providing the beta cells rest. Larger studies are needed to establish whether these effects are sufficient to prevent progression to manifest type 2 diabetes and associated cardiovascular morbidity in subjects at increased risk of developing type 2 diabetes.

Heritability of model-derived parameters of beta cell secretion during intravenous and oral glucose tolerance tests: a study of twins

AIMS/HYPOTHESIS

The genetic architecture of model-derived parameters of beta cell function has never been assessed. Therefore, we estimated heritability (h(2)) for model-derived phenotypes of insulin secretion in twins.

METHODS

Thirty-three monozygotic (MZ) and 23 dizygotic (DZ) twin pairs from the Finnish Twin Cohort Study underwent an OGTT (plasma glucose/C-peptide at 0, 30, 60, 90 and 120 min). A subset of the twin pairs (21 MZ/20 DZ) also underwent an IVGTT (frequent sampling of plasma glucose/insulin from 0 to 60 min) followed by a 160-min euglycaemic-hyperinsulinaemic clamp (45 mU.min(-1).m(-2)). Mathematical modelling was applied to the IVGTT and the OGTT to assess first-phase (readily releasable insulin [RRI]) and second-phase (sigma) secretion (IVGTT), and a global index of beta cell performance (OGTT beta index). Intraclass correlation coefficients and genetic and non-genetic components for trait variances were computed to assess the h(2) of model-derived parameters.

RESULTS

The intraclass correlation coefficients in MZ twins were 0.78 for RRI, 0.67 for sigma and 0.57 for OGTT beta index. In DZ twins the correlation coefficients were 0.23, 0.32 and 0.42, respectively. Using the most parsimonious model for each trait, the h(2)--the proportion of variance accounted for by genetic factors--was 76% (95% CI: 53-88%) for RRI, 28% (34-80%) for sigma and 53% (26-72%) for OGTT beta index.

CONCLUSIONS/INTERPRETATION

Our findings demonstrate that model-derived parameters of insulin secretion have a substantial genetic component and may be used in the search for genetic determinants of beta cell function in humans.

Polymorphisms in neprilysin gene affect the risk of Alzheimer's disease in Finnish patients

OBJECTIVES

Neprilysin (NEP) is an amyloid beta-peptide (Abeta) degrading enzyme expressed in the brain, and accumulation of Abeta is the neuropathological hallmark in Alzheimer's disease (AD). In this study we investigated whether polymorphisms in the NEP gene have an effect on the risk for AD.

METHODS

The frequencies of seven single nucleotide polymorphisms (SNPs) and apolipoprotein E (APOE) were assessed in 390 AD patients and 468 cognitively healthy controls. Genotypes of the study groups were compared using binary logistic regression analysis. Haplotype frequencies of the SNPs were estimated from genotype data.

RESULTS

Two SNPs, rs989692 and rs3736187, had significantly different allelic and genotypic frequencies (uncorrected p = 0.01) between the AD and the control subjects and haplotype analysis showed significant association between AD and NEP polymorphisms.

CONCLUSION

Taken together, these findings suggest that polymorphisms in the NEP gene increase risk for AD and support a potential role for NEP in AD.

Polymorphisms in the CYP19 gene confer increased risk for Alzheimer disease

BACKGROUND

Brain aromatase may be neuroprotective by increasing the local estrogen levels in injured neurons. Aromatase is encoded by the CYP19 gene located at 15q21.1, a chromosomal region in linkage disequilibrium (LD) with Alzheimer disease (AD) in this sample.

OBJECTIVE

To investigate whether nine single-nucleotide polymorphisms (SNP) spanning the CYP19 gene were associated with AD.

METHODS

Three hundred ninety-four patients were compared with 469 nondemented control subjects using single-locus and haplotype approaches. Haplotypes were identified using the expectation/maximization algorithm and latent class analysis, which included additional information on age, sex, and APOE polymorphism.

RESULTS

Allelic and genotypic frequencies for three adjacent SNP differed between AD and control groups. Both haplotype approaches identified an approximately 60% increase (p = 0.02) in the risk of AD for one haplotype and similar levels of excess risk irrespective of APOE polymorphism and gender.

CONCLUSION

Genetic variation in the brain aromatase gene may modify the risk for AD.

Possible association of nicastrin polymorphisms and Alzheimer disease in the Finnish population

The authors previously reported that genetic variation in the gene coding for nicastrin (NCSTN) modified risk for familial early-onset Alzheimer disease (AD) in a Dutch population-based sample. Risk was highest in patients without an APOE epsilon4 allele. Here, they evaluated if NCSTN polymorphisms increased risk of AD in the eastern Finnish population. A significant difference in one haplotype was observed in AD patients without the APOE epsilon4 allele.

Auditory adaptation is differentially impaired in familial and sporadic Alzheimer's disease

Neurophysiologic measures are particularly sensitive to alterations in attention and arousal. The purpose of this study was to evaluate the auditory adaptation of normal and mildly demented elderly people. We compared the automatic behavior of an auditory evoked potential (N100) in three age-matched groups of elderly subjects, one with familial Alzheimer's disease (AD), one with sporadic AD and one healthy group. All AD subjects corresponded clinically and neuropsychologically with the early stage of dementia. The dynamic range of auditory adaptation is known to be related to age, and normal auditory adaptation for the age was observed in our healthy aged and sporadic AD subjects, whereas the familial AD subjects lacked normal adaptation. The familial AD subjects also showed statistically significantly smaller peak amplitudes and shorter latencies of the N100 throughout the habituation test. This persistent difference in automatic habituation of sensory responses supports the view that different subtypes of AD are differentially affected. The observed differences give an objective measure of the impaired involuntary adaptive functions of neuronal networks involved in auditory processing in subtypes of AD. Since habituation reflects the most primitive stage of learning and short-term memory, altered habituation may predict faster deterioration of clinical status in the familial group of AD subjects.

Genome-wide linkage disequilibrium mapping of late-onset Alzheimer's disease in Finland

BACKGROUND

AD is a complex neurodegenerative disorder comprising several disease-associated chromosome loci. To find novel susceptibility genes for late-onset AD, a population-based genome-wide search using linkage disequilibrium (LD) mapping approach has been performed.

METHOD

Forty-seven patients with late-onset AD and 51 age-matched control subjects were carefully chosen from the same geographic area in eastern Finland, where the population is descended mainly from a small group of original founders. These subjects were initially genotyped with 366 polymorphic microsatellite markers, and a follow-up analysis was performed with additional microsatellite markers for those chromosome loci found to be associated with AD.

RESULTS

Initial genome-wide screening revealed 21 chromosomal loci significantly associated with AD in addition to the 13q12 locus described previously. Subsequent comparison of single-allele frequencies of the microsatellite markers in the AD and control groups indicated the presence both of possible risk alleles (odds ratio [OR] > 1) and of possible protective alleles (OR < 1). Screening of the LD regions with additional microsatellite markers revealed seven chromosomal loci where more than one microsatellite marker was associated with AD (1p36.12, 2p22.2, 3q28, 4p13, 10p13, 18q12.1, and 19p13.3) in addition to the 13q12 locus.

CONCLUSIONS

These genome-wide LD screening data suggest that several AD-associated chromosomal loci exist, which may encompass novel susceptibility genes for late-onset AD. Therefore, extensive screening of the genes located in the vicinity of these LD regions is necessary to elucidate their role in AD.

CLN3 protein is targeted to neuronal synapses but excluded from synaptic vesicles: new clues to Batten disease

Batten disease (juvenile neuronal ceroid lipofuscinosis, JNCL), the most common neurodegenerative disease of childhood, is caused by mutations in the CLN3 gene encoding a putative transmembrane protein. The function of CLN3 is currently unknown but it has been shown to localize in the endosomal/lysosomal compartments of non-neuronal cells. In addition, several other intracellular localizations have been proposed and the controversy of the reports suggests that CLN3 may have different intracellular localization in different cell types. Batten disease severely affects neuronal cells but leaves other organs clinically unaffected, and thus it is of utmost importance to approach the disease mechanism by studying the expression and localization of CLN3 in the brain and neuronal cells. We have analysed here CLN3 in the mouse brain using in situ hybridization, immunohistochemical staining and western blot analysis of subcellular fractions. As visual deterioration is the hallmark of Batten disease we have set up primary retinal cultures from the mouse and analysed both endogenous mouse CLN3 and Semliki Forest virus-mediated human CLN3 localization using immunofluorescence staining and confocal microscopy. We demonstrate that CLN3 is abundantly expressed in neuronal cells, especially in the cortex, hippocampus and cerebellum of the adult mouse brain. Furthermore, our results indicate that in neurons CLN3 is not solely a lysosomal protein. It is localized in the synaptosomes but, interestingly, is not targeted to the synaptic vesicles. The novel localization of CLN3 directs attention towards molecular alterations at the synapses. This should yield important clues about the mechanisms of neurodegeneration in Batten disease.

Metabolic impact of a family history of Type 2 diabetes. Results from a European multicentre study (EGIR)

BACKGROUND

Insulin resistance was found in some but not in all previous studies of non-diabetic first degree relatives of Type 2 diabetic patients. Small study groups, ethnic differences and/or non-optimal techniques may explain the conflicting results.

AIM

To study the impact of a family history of Type 2 diabetes on insulin action in a large group of non-diabetic Europeans using the 'gold standard' euglycaemic hyperinsulinaemic clamp technique.

METHODS

Non-diabetic subjects (n = 235) with a positive family history of Type 2 diabetes (FH+) and 564 subjects with no family history of diabetes (FH-) were recruited from The European Group of Insulin Resistance (EGIR) database. This database includes measurements of insulin action using the insulin clamp technique (1 mU/kg per min) in normal glucose-tolerant individuals from 20 different European centres. In a subset of subjects the measurements were performed in combination with indirect calorimetry (n = 80 vs. 213 with and without family history of Type 2 diabetes).

RESULTS

The body mass index (BMI) was slightly higher in FH+ compared with FH- (26.7 +/- 4.6 vs. 25.1 +/- 4.7 kg/m(2); P < 0.02). After correction for covariates according to differences between investigators and subject characteristics including BMI (multiple regression analysis), insulin-stimulated glucose disposal was lower in FH+ compared with FH- (P < 0.00001). Insulin-stimulated glucose oxidation was slightly increased in FH+ compared with FH-, and insulin-stimulated non-oxidative glucose metabolism was consequently markedly reduced in FH+ compared with FH- (P < 0.0005).

CONCLUSION

Insulin resistance is present in European non-diabetic relatives of Type 2 diabetic patients. The insulin resistance is independent of degree of obesity and is restricted solely to the pathway of non-oxidative glucose metabolism. Diabet. Med. 18, 533-540 (2001)

Metabolic effects of metformin in patients with impaired glucose tolerance

AIMS

To assess the effect of metformin on insulin sensitivity, glucose tolerance and components of the metabolic syndrome in patients with impaired glucose tolerance (IGT).

METHODS

Forty first-degree relatives of patients with Type 2 diabetes fulfilling WHO criteria for IGT and participating in the Botnia study in Finland were randomized to treatment with either metformin 500 mg b.i.d. or placebo for 6 months. An oral glucose tolerance test (OGTT) and a euglycaemic hyperinsulinaemic clamp in combination with indirect calorimetry was performed at 0 and 6 months. The patients were followed after stopping treatment for another 6 months in an open trial and a repeat OGTT was performed at 12 months.

RESULTS

Metformin treatment resulted in a 20% improvement in insulin-stimulated glucose metabolism (from 28.7 +/- 13 to 34.4 +/- 10.7 micromol/kg fat-free mass (FFM)/min) compared with placebo (P = 0.01), which was primarily due to an increase in glucose oxidation (from 16.6 +/- 3.6 to 19.1 +/- 4.4 micromol/kg FFM; P = 0.03) These changes were associated with a minimal improvement in glucose tolerance, which was maintained after 12 months.

CONCLUSIONS

Metformin improves insulin sensitivity in subjects with IGT primarily by reversal of the glucose fatty acid cycle. Obviously large multicentre studies are needed to establish whether these effects are sufficient to prevent progression to manifest Type 2 diabetes and associated cardiovascular morbidity and mortality. Diabet. Med. 18, 578-583 (2001)

Assessment of beta-cell function during the oral glucose tolerance test by a minimal model of insulin secretion

OBJECTIVE

To characterise the performance of beta-cell during a standard oral glucose tolerance test (OGTT).

DESIGN

Fifty-six subjects were studied. A minimal analogic model of beta-cell secretion during the OGTT was applied to all OGTTs (see below). The amount of insulin secreted over 120' in response to oral glucose (OGTT-ISR; Insulin Units 120'-1 m-2 BSA) and an index of beta-cell secretory 'force' (beta-Index; pmol.min-2.m-2 BSA) were computed with the aid of the model. In protocol A, 10 healthy subjects underwent two repeat 75 g OGTT with frequent (every 10'-15') blood sampling for glucose and C-peptide to test the reproducibility of OGTT-ISR and beta-Index with a complete or a reduced data set. In protocol B, 7 healthy subjects underwent three OGTTs (50, 100 or 150 g), to test the stability of the beta-Index under different glucose loads. In protocol C, 29 subjects (15 with normal glucose tolerance, 7 with impaired glucose tolerance and 7 with newly diagnosed type 2 diabetes) underwent two repeat 75 g OGTT with reduced (every 30' for 120') blood sampling to compare the reproducibility and the discriminant ratio (DR) of OGTT-ISR and beta-index with the insulinogenic index (IG-Index: Delta Insulin 30' - Basal/Delta Glucose 30' - Basal). In protocol D, 20 subjects (14 with normal glucose tolerance, 5 with impaired glucose tolerance and 1 with newly-diagnosed type 2 diabetes) underwent a 75 g OGTT and an intravenous glucose tolerance test (IVGTT) on separate days to explore the relationships between acute (0'-10') insulin response (AIR) during the IVGTT and beta-index and OGTT-ISR during the OGTT.

RESULTS

In all protocols, the minimal analogic model of C-peptide secretion achieved a reasonable fit of the experimental data. In protocol A, a good reproducibility of both beta-index and OGTT-ISR was observed with both complete and reduced (every 30') data sets. In protocol B, increasing the oral glucose load caused progressive increases in OGTT-ISR (from 2.63 +/- 0.70 to 5.11 +/- 0.91 Units.120'-1.m-2 BSA; P < 0.01), but the beta-index stayed the same (4.14 +/- 0.35 vs. 4.29 +/- 0.30 vs. 4.30 +/- 0.33 pmol.min-2.m-2 BSA). In protocol C, both OGTT-ISR and beta-index had lower day-to-day CVs (17.6 +/- 2.2 and 12.4 +/- 2.4%, respectively) and higher DRs (2.57 and 1.74, respectively) than the IG-index (CV: 35.5 +/- 6.3%; DR: 0.934). OGTT-ISR was positively correlated to BMI (P < 0.03), whereas beta-index was inversely related to both fasting and 2 h plasma glucose (P < 0.01 for both). In protocol D, beta-index, but not OGTT-ISR, was significantly correlated to AIR (r = 0.542, P < 0.02).

CONCLUSIONS

Analogically modelling beta-cell function during the OGTT provides a simple, useful tool for the physiological assessment of beta-cell function.

A gene conferring susceptibility to type 2 diabetes in conjunction with obesity is located on chromosome 18p11

Genome-wide nonparametric linkage analysis of 480 sib-pairs affected with type 2 diabetes revealed linkage to a previously unreported susceptibility locus on chromosome 18p11. This result improved with stringent subphenotyping using age- and sex-adjusted BMI, ultimately reaching a logarithm of odds of 3.82 (allele sharing 0.6654) at a point between markers D18S976 and D18S391 when the most obese 20% of the sample was analyzed. Several genes on chromosome 18 have been suggested as metabolic disease candidates, but none of these colocalize with our linkage result. We conclude that our results provide support for the presence of a currently uncharacterized gene on chromosome 18p, certain alleles of which confer increased susceptibility to type 2 diabetes in conjunction with obesity. We additionally observed moderate evidence for linkage to chromosome 1, near marker D1S3462; chromosome 4, near marker D4S2361; chromosome 5, near marker D5S1505; and chromosome 17, near marker D17S1301.

Palmitoyl protein thioesterase (PPT) localizes into synaptosomes and synaptic vesicles in neurons: implications for infantile neuronal ceroid lipofuscinosis (INCL)

A deficiency of palmitoyl protein thioesterase (PPT) leads to the neurodegenerative disease infantile neuronal ceroid lipofuscinosis (INCL), which is characterized by an almost complete loss of cortical neurons. PPT expressed in COS-1 cells is recognized by the mannose-6-phosphate receptor (M6PR) and is routed to lysosome, but a substantial fraction of PPT is secreted. We have here determined the neuronal localization of PPT by confocal microscopy, cryoimmunoelectron microscopy and cell fractionation. In mouse primary neurons and brain tissue, PPT is localized in synaptosomes and synaptic vesicles but not in lysosomes. Furthermore, in polarized epithelial Caco-2 cells, PPT is localized exclusively to the basolateral site, in contrast to the classical lysosomal enzyme, aspartylglucosaminidase (AGA), which is localized in the apical site. The current data imply that PPT has a role outside the lysosomes in the brain and may be associated with synaptic functioning. This finding opens a new route to study the neuropathological events associated with INCL.

Heritability of leptin levels and the shared genetic effects on body mass index and leptin in adult Finnish twins

OBJECTIVES

Leptin is involved in the regulation of body weight, but the relative role of genetic and environmental influences on inter-individual variation in leptin levels is unknown.

DESIGN AND SUBJECTS

To investigate the genetic and environmental contributions to the association of body mass index (BMI) with serum leptin levels, 58 monozygotic (MZ, 27M, 31F), and 74 like-sexed dizygotic (DZ, 32M, 42F) Finnish twin pairs aged 50--76 y were studied.

MEASUREMENTS

Serum leptin levels, weight, height, hip and waist measurements.

RESULTS

Women had higher mean leptin levels (16.8+/-9.5 ng/ml), and more overall variability in leptin levels than men (6.4+/-3.5 ng/ml; P<0.0001). Leptin levels correlated highly with BMI in men and women. Among women, the MZ and DZ pairwise correlations for leptin were 0.41 (P=0.009) and 0.07 (P=0.32), respectively. Among men the MZ and DZ pairwise correlations for leptin were 0.47 (P=0.006) and 0.23 (P=0.10). Univariate twin analysis indicated that, among women, 34% and, among men, 45% of the variance in leptin can be attributed to additive genetic effects, and the remainder to unique environmental effects. Significant non-additive genetic or shared familial effects could not be demonstrated. A bivariate twin analysis of leptin and BMI indicated that the correlation between additive genetic effects on leptin and BMI was 0.79 (95% CI 0.68--0.86) in women, and 0.68 (0.51--0.80) in men. The correlation between environmental effects on leptin and BMI was 0.77 (95% CI 0.66--0.85) in women, and 0.48 (0.26--0.66) in men.

CONCLUSION

Leptin levels are moderately heritable in older adults, and a substantial proportion of genetic effects are in common on leptin levels and obesity in both women and men. International Journal of Obesity (2001) 25, 132-137

MPO and APOEepsilon4 polymorphisms interact to increase risk for AD in Finnish males

BACKGROUND

Myeloperoxidase (MPO) is present in senile plaques and surrounding reactive microglia, but not in normal brain parenchyma. MPO in plaques is highest in APOE epsilon4 carriers, suggesting a functional interaction. An MPO promoter polymorphism (-463G/A) linked to increased MPO expression has been associated with increased risk of AD.

METHODS

To further define the possible interaction of MPO and APOE epsilon4, we examined 127 patients with AD and 174 controls from a genetically homogeneous Finnish population.

RESULTS

A significantly higher percentage of male patients with AD carried the MPO A and APOE epsilon4 alleles relative to men carrying neither allele (p < 0.001; OR, 11.4; 95% CI, 3.6 to 6.7). Male APOE epsilon4 carriers lacking the MPO A allele had an OR of 3.0 (p = 0.01; 95% CI, 1.3 to 6.9), indicating that MPO A enhances AD risk by 3.8-fold. Age at onset was lower in men carrying the MPO A and APOE epsilon4 alleles (Kaplan-Meier survival analysis; p = 0.01). Also, the MPO AA genotype was associated with selective mortality in men, but not in women. AA genotypes were absent from 159 male patients with AD and controls, representing the expected 5% to 6% in women and male controls younger than age 20. The -463A creates an estrogen receptor binding site that may contribute to these gender differences.

CONCLUSIONS

MPO A and APOE epsilon4 alleles interact to increase the risk of AD in men but not in women in this Finnish cohort.

The decrease in luteinizing hormone secretion in response to weight reduction is inversely related to the severity of insulin resistance in overweight women

Controversial effects of weight reduction on gonadotropin secretion in obesity have been reported. As a result of pulsatility, single serum samples or frequent sampling studies are somewhat limited with regard to monitoring LH and FSH concentrations. We studied follicular phase nocturnal urinary (nu) LH and FSH secretion and glucose metabolism (150-min euglycemic hyperinsulinemic clamp) during 1 menstrual cycle/30-day period before and after weight reduction in 10 severely overweight infertility patients (age, 29 +/- 3.1 yr; body mass index, 37.1 +/- 3.3 kg/m2; +/-SEM). A 6-week very low calorie diet was followed by a 4-week normocaloric period. The urinary LH and FSH results reported represent samples taken 12 to 2 days before the LH surge, or 10 consecutive samples in the case of amenorrhea. We observed a decrease of 8% (P < 0.001) in percent body fat mass and a 5% (P < 0.005) reduction in waist to hip ratio. Mean nu-LH decreased by 45% [6.06 +/- 1.05 (+/-SEM) to 3.22 +/- 0.71 IU/L], whereas mean nu-FSH remained unchanged. Insulin-stimulated glucose uptake increased by 41% (P < 0.01), which was accounted for by a significant increase in nonoxidative glucose disposal (P = 0.003). Serum sex hormone-binding globulin concentrations increased by 39% (P < 0.01), and insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) levels increased by 46% (P < 0.05). Fasting serum insulin concentrations decreased by 38%, those of leptin by 37%, those of androstenedione by 32%, those of testosterone by 20% (all P < 0.01), and those of dehydroepiandrosterone sulfate by 13% (P < 0.05). The percent change in nu-LH correlated negatively with glucose uptake (r = -0.76; P < 0.01) and the increase in serum sex hormone-binding globulin (r = -0.85; P < 0.005) and positively with the percent change in waist to hip ratio (r = 0.79; P < 0.01). The absolute nu-LH levels after weight reduction correlated significantly with fasting insulin concentrations (r = 0.88; P < 0.001) and negatively with glucose uptake (r = -0.67; P < 0.05). No significant relationships were found between absolute levels or changes in nu-LH concentrations and leptin, IGF-I, IGFBP-3, or IGFBP-1 concentrations. Our findings suggest that weight reduction with a very low calorie diet results in a decrease in nu-LH concentrations, a reduction in the LH/FSH ratio, and FSH predominance favoring folliculogenesis. The decrease in LH concentrations is inversely related to the severity of insulin resistance. It is possible that the decrease in LH secretion with weight reduction is more dependent on the absolute levels of insulin sensitivity than on the degree of general adiposity.

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.