Microstructural Tissue Changes in Alzheimer Disease Brains: Insights from Magnetization Transfer Imaging.

BACKGROUND AND PURPOSE: Reductions in magnetization transfer ratio have been associated with brain microstructural damage. We aim to compare magnetization transfer ratio in global and regional GM and WM between individuals with Alzheimer disease and healthy control participants to analyze the relationship between magnetization transfer ratio and cognitive functioning in Alzheimer disease. MATERIALS AND METHODS: In this prospective study, participants with Alzheimer disease and a group of age-matched healthy control participants underwent clinical examinations and 3T MR imaging. Magnetization transfer ratios were determined in the cortex, AD-signature regions, normal-appearing WM, and WM hyperintensities. RESULTS: Seventy-seven study participants (mean age ± SD, 72 ± 8 years; 47 female) and 77 age-matched healthy control participants (mean age ± SD, 72 ± 8 years; 44 female) were evaluated. Magnetization transfer ratio values were lower in patients with Alzheimer disease than in healthy control participants in all investigated regions. When adjusting for atrophy and extent of WM hyperintensities, significant differences were seen in the global cortex (OR = 0.47; 95% CI: 0.22, 0.97; P = .04), in Alzheimer disease-signature regions (OR = 0.31; 95% CI: 0.14, 0.67; P = .003), in normal-appearing WM (OR = 0.59; 95% CI: 0.39, 0.88; P = .01), and in WM hyperintensities (OR = 0.18; 95% CI: 0.09, 0.33; P ≤ .001). The magnetization transfer ratio in these regions was an independent determinant of AD. When correcting for atrophy and WM hyperintensity extent, lower GM magnetization transfer ratios were associated with poorer global cognition, language function, and constructional praxis. CONCLUSIONS: Alzheimer disease is associated with magnetization transfer ratio reductions in GM and WM regions of the brain. Lower magnetization transfer ratios in the entire cortex and AD-signature regions contribute to cognitive impairment independent of brain atrophy and WM damage.

Application of microprobe-based flank method analysis of Fe3+ in garnet of North Qilian eclogite and its geological implication.

A newly developed microprobe-based methodology (the Flank Method) for Fe3+/ΣFe quantification has been successfully applied to some natural garnets from the North Qilian eclogites by JEOL JXA-8100 microprobe at Peking University. The results demonstrated an obvious discrepancy in comparison with the outcomes by conventional stoichiometric calculations. This methodology allows to measure the Fe3+/ΣFe ratio and perform elemental analyses simultaneously in the same condition. Accurate in-situ measurement of Fe3+ content in garnet may bring certain impact on the garnet-based P-T estimation. According to the compositional zonation displayed in the studied eclogitic garnets from North Qilian, a prograde metamorphic PT path from 19.5 kbar, 520 °C to 22 kbar, 600 °C was reconstructed. More interestingly, the measured Fe3+/ΣFe ratios in garnets decreasing from core to rim may probably imply that the oxygen fugacity (fO2) declines with the depth of the subduction zone.

Lower Magnetization Transfer Ratio in the Forceps Minor Is Associated with Poorer Gait Velocity in Older Adults.

BACKGROUND AND PURPOSE: Gait disturbances in the elderly are disabling and a major public health issue but are poorly understood. In this multimodal MR imaging study, we used 2 voxel-based analysis methods to assess the voxelwise relationship of magnetization transfer ratio and white matter hyperintensity location with gait velocity in older adults. MATERIALS AND METHODS: We assessed 230 community-dwelling participants of the Austrian Stroke Prevention Family Study. Every participant underwent 3T MR imaging, including magnetization transfer imaging. Voxel-based magnetization transfer ratio-symptom mapping correlated the white matter magnetization transfer ratio of each voxel with gait velocity. To assess a possible relationship between white matter hyperintensity location and gait velocity, we applied voxel-based lesion-symptom mapping. RESULTS: We found a significant association between the magnetization transfer ratio within the forceps minor and gait velocity (ß = 0.134; 95% CI, 0.011-0.258; P = .033), independent of demographics, general physical performance, vascular risk factors, and brain volume. White matter hyperintensities did not significantly change this association. CONCLUSIONS: Our study provides new evidence for the importance of magnetization transfer ratio changes in gait disturbances at an older age, particularly in the forceps minor. The histopathologic basis of these findings is yet to be determined.

EFNS-ENS/EAN Guideline on concomitant use of cholinesterase inhibitors and memantine in moderate to severe Alzheimer's disease.

BACKGROUND AND PURPOSE: Previous studies have indicated clinical benefits of a combination of cholinesterase inhibitors (ChEI) and memantine over ChEI monotherapy in Alzheimer's disease (AD). Our objective was the development of guidelines on the question of whether combined ChEI/memantine treatment rather than ChEI alone should be used in patients with moderate to severe AD to improve global clinical impression (GCI), cognition, behaviour and activities of daily living (ADL). METHODS: A systematic review and meta-analysis of randomized controlled trials based on a literature search in ALOIS, the register of the Cochrane Dementia and Cognitive Improvement Group, was carried out with subsequent guideline development according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. RESULTS: Pooled data from four trials including 1549 AD patients in the moderate to severe disease stage demonstrated significant beneficial effects of combination therapy compared to ChEI monotherapy for GCI [standardized mean difference (SMD) -0.20; 95% confidence interval (CI) -0.31; -0.09], cognitive functioning (SMD -0.27, 95% CI -0.37; -0.17) and behaviour (SMD -0.19; 95% CI -0.31; -0.07). The quality of evidence was high for behaviour, moderate for cognitive function and GCI and low for ADL. Agreement of panellists was reached after the second round of the consensus finding procedure. The desirable effects of combined ChEI and memantine treatment were considered to outweigh undesirable effects. The evidence was weak for cognition, GCI and ADL so that the general recommendation for using combination therapy was weak. CONCLUSIONS: We suggest the use of a combination of ChEI plus memantine rather than ChEI alone in patients with moderate to severe AD. The strength of this recommendation is weak.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949).

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Anticardiolipin antibodies are associated with cognitive dysfunction in stroke-free individuals.

BACKGROUND AND PURPOSE: The presence of anticardiolipin antibodies (aCLs) has been associated with vascular occlusive events. The role of aCLs as a risk factor for stroke has been a matter of debate, and scarce information exists on the relationship between aCLs and other cerebral disorders. Reports exist for seizures, chorea and subtle cognitive dysfunction. The association between aCLs and cognition was further explored and the relationship between aCL titres and brain magnetic resonance imaging (MRI) findings was evaluated in a large cohort of community-dwelling individuals. METHODS: The study cohort was drawn from the Austrian Stroke Prevention Study. A total of 1895 subjects had a complete risk factor assessment and measurement of aCL titres in serum. Participants were classified as aCL positive if either the immunoglobulin G (IgG) or IgM aCL titres were elevated (IgG > 21 U/ml, IgM > 12 U/ml). All subjects were also categorized based on the quartile distribution of IgG and IgM isotype titres. All underwent cognitive testing by the Mini Mental State Examination (MMSE) and a random sample of 947 participants also underwent brain MRI. RESULTS: aCL positive participants performed worse on the MMSE. IgG but not IgM isotype titres related to worse performance on the MMSE. No significant association existed with vascular brain abnormalities including lacunes, cortical infarcts and white matter lesions. CONCLUSIONS: These data support the view that in normal elderly persons increasing IgG aCL titres relate to global cognitive dysfunction. It is unlikely that structural brain lesions are responsible for this finding.

Characteristics of Yersinia enterocolitica biotype 1A strains isolated from patients and asymptomatic carriers.

Yersinia enterocolitica biotype 1A strains are frequently isolated from the environment, foods, and animals, and also from humans with yersiniosis. There are controversial reports on the pathogenicity of biotype 1A strains. In this study, 811 fecal samples from asymptomatic humans from Switzerland were studied for the presence of Y. enterocolitica. Nine (1.1%) of the 811 samples were positive for Y. enterocolitica 1A. These strains were compared with 12 Y. enterocolitica 1A strains from Swiss patients with diarrhea isolated in the same year. Almost all (20/21) Y. enterocolitica 1A strains carried the ystB gene, seven strains carried the hreP gene, and none carried the ail, ystA, myfA, yadA, or virF genes. Most (17/21) Y. enterocolitica 1A strains belonged to two major clusters, A and B, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Strains of cluster B were only isolated from humans with diarrhea; however, ystB and hreP genes were detected in strains from both clinical and non-clinical samples and from strains of clusters A and B. Using ribotyping, six restriction patterns among biotype 1A strains were obtained with HindIII enzyme. The most common ribotype (RT I) was found in strains isolated from humans with and without diarrhea. All biotype 1A strains had a unique NotI profile by pulsed-field gel electrophoresis (PFGE), showing a very high genetic diversity. In this study, Y. enterocolitica 1A strains from clinical and non-clinical samples could not be clearly differentiated from each other. More research is needed in order to prove that biotype 1A strains are a primary cause for human yersiniosis and not only a secondary finding.

Bacteriological survey of ready-to-eat lettuce, fresh-cut fruit, and sprouts collected from the Swiss market.

The consumption of ready-to-eat fresh vegetables has increased significantly in the recent decades. So far, no data are available on the bacteriological burden and the prevalence of foodborne pathogens in ready-to-eat lettuce, fresh-cut fruit, and sprouts on the Swiss market. This study was based on investigations carried out during 2 months of the summer season in 2011. Samples of 142 salads, 64 fresh-cut fruit, and 27 sprouts were included in this study. Escherichia coli, an indicator microorganism for fecal contamination, was only found in 5 lettuce samples, with amounts ranging between 2 and 3 log CFU/g. No Salmonella spp. were detected from any of the 233 samples analyzed in this study, and a low occurrence was found for contamination with L. monocytogenes, Shiga toxin-producing E. coli, enteropathogenic E. coli, and Cronobacter. From the results of the present study, we conclude that even in a country where the use of chlorine solutions to sanitize fruits and vegetables in the fresh-cut industry is not allowed, it is possible to produce ready-to-eat lettuce, fresh-cut fruit, and sprouts with high microbiological standards. Strict maintenance of good practices of hygiene at preharvest, harvest, and postharvest levels is of central importance to ensure both public health protection and product quality.

Bacteriophage amplification assay for detection of Listeria spp. using virucidal laser treatment

A protocol for the bacteriophage amplification technique was developed for quantitative detection of viable Listeria monocytogenes cells using the A511 listeriophage with plaque formation as the end-point assay. Laser and toluidine blue O (TBO) were employed as selective virucidal treatment for destruction of exogenous bacteriophage. Laser and TBO can bring a total reduction in titer phage (ca. 10(8) pfu/mL) without affecting the viability of L. monocytogenes cells. Artificially inoculated skimmed milk revealed mean populations of the bacteria as low as between 13 cfu/mL (1.11 log cfu/mL), after a 10-h assay duration. Virucidal laser treatment demonstrated better protection of Listeria cells than the other agents previously tested. The protocol was faster and easier to perform than standard procedures. This protocol constitutes an alternative for rapid, sensitive and quantitative detection of L. monocytogenes.

Application of a real-time PCR-based system for monitoring of O26, O103, O111, O145 and O157 Shiga toxin-producing Escherichia coli in cattle at slaughter.

Faecal samples were collected from 573 slaughtered cattle aged between three and 24 months in seven abattoirs. After enrichment (mTSB with novobiocin), samples were screened by real-time PCR first for stx and if positive, tested for the top-five Shiga toxin-producing Escherichia coli (STEC) serogroups using PCR assays targeting genes specific for serogroups O26, O103, O111, O145 and O157. Of 563 samples with available results, 74.1% tested positive for stx genes. Amongst them, the serogroups O145, O103, O26, O157 and O111 were detected in 41.9%, 25.9%, 23.9%, 7.8% and 0.8%, respectively. From 95 O26, 166 O145 and 30 O157 PCR-positive samples, 17 O26, 28 O145 and 12 O157 strains were isolated by colony hybridization after immunomagnetic separation. The 17 O26 strains were eae-positive, but only nine strains harboured stx (eight possessing stx1 and one stx2). Of the 28 O145 strains, ten were eae-positive including four harbouring stx1 or stx2, whereas 18 were negative for stx and eae. Five of the 12 O157 strains harboured stx2 and eae, did not ferment sorbitol, and were identified as STEC O157:H7/H⁻. The other seven O157 strains were negative for stx and eae or positive only for eae. Shiga toxin genes and the top-five STEC serogroups were frequently found in young Swiss cattle at slaughter, but success rates for strain isolation were low and only few strains showed a virulence pattern of human pathogenic STEC.

The human C-type lectin-like receptor CLEC-1 is upregulated by TGF-ß and primarily localized in the endoplasmic membrane compartment.

The orphan receptor CLEC-1 is part of a subfamily of C-type lectin-like receptors, which is encoded in the human natural killer gene complex and comprises several pattern recognition receptors important for innate immune functions. As information on human CLEC-1 is still very limited, we aimed to further characterize this receptor. Similar to another subfamily member, LOX-1, expression of CLEC-1 mRNA was detected in myeloid cells as well as in endothelial cells. CLEC-1 protein displayed N-linked glycosylation and formed dimers. However, in contrast to other members of the subfamily, expression levels were upregulated by transforming growth factor (TGF)-ß, but not significantly affected by proinflammatory stimuli. It is intriguing that human CLEC-1 could only be detected intracellularly with a staining pattern resembling endoplasmic reticulum proteins. Neither TGF-ß nor inflammatory stimuli could promote significant translocation to the cell surface. These findings are in accordance with a primarily intracellular localization and function of human CLEC-1.

Bacteriophage amplification assay for detection of Listeria spp. using virucidal laser treatment.

A protocol for the bacteriophage amplification technique was developed for quantitative detection of viable Listeria monocytogenes cells using the A511 listeriophage with plaque formation as the end-point assay. Laser and toluidine blue O (TBO) were employed as selective virucidal treatment for destruction of exogenous bacteriophage. Laser and TBO can bring a total reduction in titer phage (ca. 10(8) pfu/mL) without affecting the viability of L. monocytogenes cells. Artificially inoculated skimmed milk revealed mean populations of the bacteria as low as between 13 cfu/mL (1.11 log cfu/mL), after a 10-h assay duration. Virucidal laser treatment demonstrated better protection of Listeria cells than the other agents previously tested. The protocol was faster and easier to perform than standard procedures. This protocol constitutes an alternative for rapid, sensitive and quantitative detection of L. monocytogenes.

Topology and conduction in the inferior right atrial isthmus measured in rabbit hearts.

The inferior right atrial isthmus consisting of the terminal crest, the network of pectinate muscles, and the vestibule shows very complex anatomical structure. It is seen as potential substrate for atrial flutter. In this work we present results from an electro-anatomical characterization of this region based on Cardiac Near Field recordings taken from five preparations of rabbit atrium. Pectinate muscles in the region of interest were divided into three segments: central as well as proximal and distal with respect to the terminal crest. Electrograms measured in these segments showed differences in the degree of fractionation, i.e. the numbers of distinct local activation events, indicating heterogeneities in microstructure. From 249 recording sites 63.9% showed no fractionation, 26.9% showed two activation events, and 9.2% were highly fractionated. The proximal starting sequence of activation in a series of adjacent pectinate muscles is not sorted but rather seems to be arbitrary. The same applies to the arrival sequence of activation close to the vestibule. In the network of pectinate muscles on average one proximal segment branches into two central strands and two central strands merge into one distal stem.

Evolutionary development and expression pattern of the myeloid lectin-like receptor gene family encoded within the NK gene complex.

The myeloid cluster within the natural killer (NK) gene complex comprises several C-type lectin-like receptor genes of diverse and highly important functions in the immune system such as LOX-1 and DECTIN-1. Based on sequences that have become available by whole genome sequencing, we conducted a comparison of the human, chimpanzee, mouse and rat NK gene complex to better characterize this gene family and additional genes of this region in regard of their phylogenetic relationship and evolution within the complex. We found that the arrangement of genes within the primate cluster differs from the order and orientation of the corresponding genes in the rodent complex which can be explained by evolutionary duplication and inversion events. Analysis of individual genes revealed a high sequence conservation supporting the prime importance of the encoded proteins. Expression analyses of the more recently described CLEC12B and CLEC9A genes displayed not only mRNA expression in monocytic and dendritic cells, but in contrast to other members of the family also in lymphocytes. Further, two additional genes were identified, which do not encode proteins with lectin-like domain structure and seem to be widely expressed.

Cardiomyogenic differentiation of human bone marrow mesenchymal cells: Role of cardiac extract from neonatal rat cardiomyocytes.

Bone marrow mesenchymal stromal cells (BM-MSCs) with regenerative potential have been identified in heart. Whether these cells become new cardiac lineage cells by phenomena of transdifferentiation or fusion is also being investigated. Although, these mechanisms give cardiomyocytes, it has to be considered that MSCs transplantation could carry out ossification and calcification processes. An alternative might be the use of myocytes; however, the problem is the arrythmia. For those reasons, is that we investigated how to obtain cardiomyocyte-like cells from human MSCs (hMSCs). The aim of the present work was to evaluate a nuclear reprogramming of the hMSCs by a neonatal rat cardiomyocytes extract (EX) using Streptolysin O (SLO) treatment. hMSCs treated with 57.5ng/ml SLO presented ball-like, stick-like and myotube-like morphology. In the absence of cardiomyogenic stimuli, hMSCs expressed markers of cardiac phenotype-like sarcomeric alpha-actinin, connexin-43 and GATA-4. However, when hMSCs were treated with SLO+EX or 10 microM of 5-azacytidine (5-AZA), the expression of these markers were significantly increased and furthermore, expressed SERCA-2, cardiac Troponin I, beta-MyHC, desmin, MLC-2a and MLC-2v thus showing the phenotype of mature cardiomyocytes. PCR analysis showed that cardiomyocyte-related genes, such as beta1-adrenergic receptor (beta1-AR), MLC-2a and cardiac Troponin T, were expressed after SLO+EX treatment like with 5-AZA. We concluded that the extract of neonatal rat cardiomyocytes could promote a nuclear modification of hMSCs to cardiomyogenic-like cells differentiation. Since the 5-AZA treatment appears to be genotoxic and taking into account the obtained results, the nuclear reprogramming by cell extract may be an approach leading to the identification of soluble factors that drives the reprogramming.

Characterization of potentially virulent non-O1/non-O139 Vibrio cholerae strains isolated from human patients.

Traditional methods of typing Vibrio cholerae define virulent strains according to their recognition by sera directed against the known epidemic serogroups O1 and O139, overlooking potentially virulent non-O1/non-O139 strains. Here, we have undertaken the characterization of eight clinical isolates of non-O1/non-O139 V. cholerae, collected during cholera outbreaks in Brazil. Seven of these were typed as O26 and one, 17155, was defined as non-typable. A PCR-based approach has previously detected in these strains several virulence genes derived from the CTXvarphi prophage and generally associated with pathogenic strains. Here, the presence of the O1-specific wbeN gene was investigated through PCR and found to be restricted to strain 17155, as well as one of the O26 strains, 4756, although neither strain was recognized by O1-specific antisera. The same two isolates were the only strains able to express the cholera toxin in culture, assayed by western blotting. They also possessed four repeats of the heptanucleotide TTTTGAT upstream of the ctxAB genes encoding the cholera toxin. The remaining strains possessed only two intact repeats, whereas pathogenic O1 possessed four to six repeats. To define their evolutionary relationships, selected 16S-23S intergenic rRNA spacer regions were sequenced from the various strains and the resulting sequences used to build phylogenetic trees. Strains 4756 and 17155 always clustered with control O1 strains, whereas the remaining O26 strains clustered separately. These results confirm that, despite their serological phenotype, these two strains are genotypically related to O1 strains and potentially able to produce epidemic cholera.

Vibrio parahaemolyticus serovar O3:K6 gastroenteritis in northeast Brazil.

AIMS: To examine the virulence factors and the genetic relationship isolates of the serogroup O3 of Vibrio parahaemolyticus in outbreaks of diarrhoea in the northeast region of Brazil. METHODS AND RESULTS: Eighteen samples of the O3:K6 and O3:KUT serotypes of V. parahaemolyticus were analysed by multiplex polymerase chain reaction (m-PCR) for detection of the tl, tdh and trh genes, by random-amplified polymorphic DNA (RAPD) using two primers, and by amplification of the rDNA 16S-23S region. The gene tl was amplified in all the samples, tdh in 16 while trh in none; amplification of rDNA 16S-23S generated only one profile; each RAPD primer produced two amplification patterns allowing grouping two tdh(-) Kanagawa-negative isolates. CONCLUSIONS: V. parahaemolyticus with characteristics of the pandemic clone appears to be widely disseminated in the studied region. Because of the genetic uniformity of the isolates, elucidation of outbreaks or tracking the source of contamination by the present molecular techniques seems useless. SIGNIFICANCE AND IMPACT OF THE STUDY: Detection of V. parahaemolyticus with virulence potential of pandemic clone from two outbreaks and from several isolated gastroenteritis cases points out the need for inclusion of this micro-organism in the Brazilian routine monitoring of the diarrhoeas for elucidation of their aetiology.