The η-secretase-derived APP fragment ηCTF is localized in Golgi, endosomes and extracellular vesicles and contributes to Aβ production

The processing of the amyloid precursor protein (APP) is one of the key events contributing to Alzheimer's disease (AD) etiology. Canonical cleavages by β- and γ-secretases lead to Aβ production which accumulate in amyloid plaques. Recently, the matrix metalloprotease MT5-MMP, referred to as η-secretase, has been identified as a novel APP cleaving enzyme producing a transmembrane fragment, ηCTF that undergoes subsequent cleavages by α- and β-secretases yielding the Aηα and Aηβ peptides, respectively. The functions and contributions of ηCTF and its related fragments to AD pathology are poorly understood. In this study, we designed a novel immunological probe referred to as ηCTF-NTer antibody that specifically interacts with the N-terminal part of ηCTF targeting ηCTF, Aηα, Aηβ but not C99, C83 and Aβ. We examined the fate and localization of ηCTF fragment in various cell models and in mice. We found that overexpressed ηCTF undergoes degradation in the proteasomal and autophagic pathways and accumulates mainly in the Golgi and in endosomes. Moreover, we observed the presence of ηCTF in small extracellular vesicles purified from neuroblastoma cells or from mouse brains expressing ηCTF. Importantly, the expression of ηCTF in fibroblasts devoid on APP leads to Aβ production demonstrating its contribution to the amyloidogenic pathway. Finally, we observed an ηCTF-like immunoreactivity around amyloid plaques and an age-dependent accumulation of ηCTF in the triple-transgenic mouse AD model. Thus, our study suggests that the ηCTF fragment likely contributes to AD pathology by its exosomal spreading and involvement in Aβ production.

Infant nutrition affects the microbiota-gut-brain axis: Comparison of human milk vs. infant formula feeding in the piglet model

Early nutrition plays a dominant role in infant development and health. It is now understood that the infant diet impacts the gut microbiota and its relationship with gut function and brain development. However, its impact on the microbiota-gut-brain axis has not been studied in an integrative way. The objective here was to evaluate the effects of human milk (HM) or cow’s milk based infant formula (IF) on the relationships between gut microbiota and the collective host intestinal-brain axis. Eighteen 10-day-old Yucatan mini-piglets were fed with HM or IF. Intestinal and fecal microbiota composition, intestinal phenotypic parameters, and the expression of genes involved in several gut and brain functions were determined. Unidimensional analyses were performed, followed by multifactorial analyses to evaluate the relationships among all the variables across the microbiota-gut-brain axis. Compared to IF, HM decreased the α-diversity of colonic and fecal microbiota and modified their composition. Piglets fed HM had a significantly higher ileal and colonic paracellular permeability assessed by ex vivo analysis, a lower expression of genes encoding tight junction proteins, and a higher expression of genes encoding pro-inflammatory and anti-inflammatory immune activity. In addition, the expression of genes involved in endocrine function, tryptophan metabolism and nutrient transport was modified mostly in the colon. These diet-induced intestinal modifications were associated with changes in the brain tissue expression of genes encoding the blood-brain barrier, endocrine function and short chain fatty acid receptors, mostly in hypothalamic and striatal areas. The integrative approach underlined specific groups of bacteria (Veillonellaceae, Enterobacteriaceae, Lachnospiraceae, Rikenellaceae, and Prevotellaceae) associated with changes in the gut-brain axis. There is a clear influence of the infant diet, even over a short dietary intervention period, on establishment of the microbiota-gut-brain axis.

Transforming Anesthesia Data Into the Observational Medical Outcomes Partnership Common Data Model: Development and Usability Study

BACKGROUND

Electronic health records (EHRs, such as those created by an anesthesia management system) generate a large amount of data that can notably be reused for clinical audits and scientific research. The sharing of these data and tools is generally affected by the lack of system interoperability. To overcome these issues, Observational Health Data Sciences and Informatics (OHDSI) developed the Observational Medical Outcomes Partnership (OMOP) common data model (CDM) to standardize EHR data and promote large-scale observational and longitudinal research. Anesthesia data have not previously been mapped into the OMOP CDM.

OBJECTIVE

The primary objective was to transform anesthesia data into the OMOP CDM. The secondary objective was to provide vocabularies, queries, and dashboards that might promote the exploitation and sharing of anesthesia data through the CDM.

METHODS

Using our local anesthesia data warehouse, a group of 5 experts from 5 different medical centers identified local concepts related to anesthesia. The concepts were then matched with standard concepts in the OHDSI vocabularies. We performed structural mapping between the design of our local anesthesia data warehouse and the OMOP CDM tables and fields. To validate the implementation of anesthesia data into the OMOP CDM, we developed a set of queries and dashboards.

RESULTS

We identified 522 concepts related to anesthesia care. They were classified as demographics, units, measurements, operating room steps, drugs, periods of interest, and features. After semantic mapping, 353 (67.7%) of these anesthesia concepts were mapped to OHDSI concepts. Further, 169 (32.3%) concepts related to periods and features were added to the OHDSI vocabularies. Then, 8 OMOP CDM tables were implemented with anesthesia data and 2 new tables (EPISODE and FEATURE) were added to store secondarily computed data. We integrated data from 5,72,609 operations and provided the code for a set of 8 queries and 4 dashboards related to anesthesia care.

CONCLUSIONS

Generic data concerning demographics, drugs, units, measurements, and operating room steps were already available in OHDSI vocabularies. However, most of the intraoperative concepts (the duration of specific steps, an episode of hypotension, etc) were not present in OHDSI vocabularies. The OMOP mapping provided here enables anesthesia data reuse.

Temporal trends in mortality and readmission after acute heart failure: a systematic review and meta-regression in the past four decades

AIMS

Acute heart failure (AHF) is frequent and life-threatening disease. However, innovative AHF therapies have remained limited, and care is based on experts' opinion. Temporal trends and benefits of long-term oral cardiovascular medications on AHF outcomes remain uncertain.

METHODS AND RESULTS

This study is registered with PROSPERO (CRD42018099885). A systematic review ranging from 1980 to 2017, searched AHF studies with more than 100 patients that reported death and/or readmission. Primary outcomes were temporal trends, assessed by meta-regression, for 30-day or 1-year all-cause death and/or readmission rates. Secondary outcomes were temporal trends of oral cardiovascular therapies and their influence on primary outcomes. Among the 45 143 studies screened, 285 were included, representing 15 million AHFs. In the past decades, though mortality and readmission remain high, there was a decline in 30-day all-cause death [odds ratio (OR) for a 10-year increment: 0.74, 95% confidence interval (CI) 0.61-0.91; P = 0.004] that persisted at 1 year (OR 0.86, 95% CI 0.77-0.96; P = 0.007), while 30-day and 1-year all-cause readmission rate remained roughly unchanged. Trends of primary outcomes were linear and did not differ among continents. Decline in 1-year all-cause death rate correlated with high proportions of oral or beta-blockers, especially when combined with oral renin-angiotensin-aldosterone system inhibitors, but not with diuretics while trends in readmission remained unchanged with these therapies.

CONCLUSIONS

Although AHF outcomes remain poor, the present study revealed global favourable trends of survival after AHF episodes probably associated with greater use of oral neurohormonal antagonists. The present study urges to implement the combination of oral renin-angiotensin-aldosterone system inhibitors and beta-blockers in patients at risk of AHF.

Accumulation of amyloid precursor protein C-terminal fragments triggers mitochondrial structure, function, and mitophagy defects in Alzheimer's disease models and human brains

Several lines of recent evidence indicate that the amyloid precursor protein-derived C-terminal fragments (APP-CTFs) could correspond to an etiological trigger of Alzheimer's disease (AD) pathology. Altered mitochondrial homeostasis is considered an early event in AD development. However, the specific contribution of APP-CTFs to mitochondrial structure, function, and mitophagy defects remains to be established. Here, we demonstrate in neuroblastoma SH-SY5Y cells expressing either APP Swedish mutations, or the β-secretase-derived APP-CTF fragment (C99) combined with β- and γ-secretase inhibition, that APP-CTFs accumulation independently of Aβ triggers excessive mitochondrial morphology alteration (i.e., size alteration and cristae disorganization) associated with enhanced mitochondrial reactive oxygen species production. APP-CTFs accumulation also elicit basal mitophagy failure illustrated by enhanced conversion of LC3, accumulation of LC3-I and/or LC3-II, non-degradation of SQSTM1/p62, inconsistent Parkin and PINK1 recruitment to mitochondria, enhanced levels of membrane and matrix mitochondrial proteins, and deficient fusion of mitochondria with lysosomes. We confirm the contribution of APP-CTFs accumulation to morphological mitochondria alteration and impaired basal mitophagy in vivo in young 3xTgAD transgenic mice treated with γ-secretase inhibitor as well as in adeno-associated-virus-C99 injected mice. Comparison of aged 2xTgAD and 3xTgAD mice indicates that, besides APP-CTFs, an additional contribution of Aβ to late-stage mitophagy activation occurs. Importantly, we report on mitochondrial accumulation of APP-CTFs in human post-mortem sporadic AD brains correlating with mitophagy failure molecular signature. Since defective mitochondria homeostasis plays a pivotal role in AD pathogenesis, targeting mitochondrial dysfunctions and/or mitophagy by counteracting early APP-CTFs accumulation may represent relevant therapeutic interventions in AD.

The Transcription Factor EB Reduces the Intraneuronal Accumulation of the Beta-Secretase-Derived APP Fragment C99 in Cellular and Mouse Alzheimer’s Disease Models

Brains that are affected by Alzheimer’s disease (AD) are characterized by the overload of extracellular amyloid β (Aβ) peptides, but recent data from cellular and animal models propose that Aβ deposition is preceded by intraneuronal accumulation of the direct precursor of Aβ, C99. These studies indicate that C99 accumulation firstly occurs within endosomal and lysosomal compartments and that it contributes to early-stage AD-related endosomal-lysosomal-autophagic defects. Our previous work also suggests that C99 accumulation itself could be a consequence of defective lysosomal-autophagic degradation. Thus, in the present study, we analyzed the influence of the overexpression of the transcription factor EB (TFEB), a master regulator of autophagy and lysosome biogenesis, on C99 accumulation occurring in both AD cellular models and in the triple-transgenic mouse model (3xTgAD). In the in vivo experiments, TFEB overexpression was induced via adeno-associated viruses (AAVs), which were injected either into the cerebral ventricles of newborn mice or administrated at later stages (3 months of age) by stereotaxic injection into the subiculum. In both cells and the 3xTgAD mouse model, exogenous TFEB strongly reduced C99 load and concomitantly increased the levels of many lysosomal and autophagic proteins, including cathepsins, key proteases involved in C99 degradation. Our data indicate that TFEB activation is a relevant strategy to prevent the accumulation of this early neurotoxic catabolite.

Targeting γ-secretase triggers the selective enrichment of oligomeric APP-CTFs in brain extracellular vesicles from Alzheimer cell and mouse models

Background

We recently demonstrated an endolysosomal accumulation of the β-secretase-derived APP C-terminal fragment (CTF) C99 in brains of Alzheimer disease (AD) mouse models. Moreover, we showed that the treatment with the γ-secretase inhibitor (D6) led to further increased endolysosomal APP-CTF levels, but also revealed extracellular APP-CTF-associated immunostaining. We here hypothesized that this latter staining could reflect extracellular vesicle (EV)-associated APP-CTFs and aimed to characterize these γ-secretase inhibitor-induced APP-CTFs.

Methods

EVs were purified from cell media or mouse brains from vehicle- or D6-treated C99 or APP_swedish expressing cells/mice and analyzed for APP-CTFs by immunoblot. Combined pharmacological, immunological and genetic approaches (presenilin invalidation and C99 dimerization mutants (GXXXG)) were used to characterize vesicle-containing APP-CTFs. Subcellular APP-CTF localization was determined by immunocytochemistry.

Results

Purified EVs from both AD cell or mouse models were enriched in APP-CTFs as compared to EVs from control cells/brains. Surprisingly, EVs from D6-treated cells not only displayed increased C99 and C99-derived C83 levels but also higher molecular weight (HMW) APP-CTF-immunoreactivities that were hardly detectable in whole cell extracts. Accordingly, the intracellular levels of HMW APP-CTFs were amplified by the exosomal inhibitor GW4869. By combined pharmacological, immunological and genetic approaches, we established that these HMW APP-CTFs correspond to oligomeric APP-CTFs composed of C99 and/or C83. Immunocytochemical analysis showed that monomers were localized mainly to the trans-Golgi network, whereas oligomers were confined to endosomes and lysosomes, thus providing an anatomical support for the selective recovery of HMW APP-CTFs in EVs. The D6-induced APP-CTF oligomerization and subcellular mislocalization was indeed due to γ-secretase blockade, since it similarly occurred in presenilin-deficient fibroblasts. Further, our data proposed that besides favoring APP-CTF oligomerization by preventing C99 proteolysis, γ-secretase inhibiton also led to a defective SorLA-mediated retrograde transport of HMW APP-CTFs from endosomal compartments to the TGN.

Conclusions

This is the first study to demonstrate the presence of oligomeric APP-CTFs in AD mouse models, the levels of which are selectively enriched in endolysosomal compartments including exosomes and amplified by γ-secretase inhibition. Future studies should evaluate the putative contribution of these exosome-associated APP-CTFs in AD onset, progression and spreading.

Does Intraneuronal Accumulation of Carboxyl-terminal Fragments of the Amyloid Precursor Protein Trigger Early Neurotoxicity in Alzheimer’s Disease?

Background:

Alzheimer’s disease (AD) is associated with extracellular accumulation and aggregation of amyloid β (Aβ) peptides ultimately seeding in senile plaques. Recent data show that their direct precursor C99 (βCTF) also accumulates in AD-affected brain as well as in AD-like mouse models. C99 is consistently detected much earlier than Aβ, suggesting that this metabolite could be an early contributor to AD pathology. C99 accumulates principally within endolysosomal and autophagic structures and its accumulation was described as both a consequence and one of the causes of endolysosomalautophagic pathology, the occurrence of which has been documented as an early defect in AD. C99 was also accompanied by C99-derived C83 (αCTF) accumulation occurring within the same intracellular organelles. Both these CTFs were found to dimerize leading to the generation of higher molecular weight CTFs, which were immunohistochemically characterized in situ by means of aggregate-specific antibodies.

Discussion:

Here, we discuss studies demonstrating a direct link between the accumulation of C99 and C99-derived APP-CTFs and early neurotoxicity. We discuss the role of C99 in endosomal-lysosomalautophagic dysfunction, neuroinflammation, early brain network alterations and synaptic dysfunction as well as in memory-related behavioral alterations, in triple transgenic mice as well as in newly developed AD animal models.

Conclusion:

This review summarizes current evidence suggesting a potential role of the β -secretasederived APP C-terminal fragment C99 in Alzheimer’s disease etiology

β-Amyloid Precursor Protein Intracellular Domain Controls Mitochondrial Function by Modulating Phosphatase and Tensin Homolog-Induced Kinase 1 Transcription in Cells and in Alzheimer Mice Models

BACKGROUND

Mitophagy and mitochondrial dynamics alterations are two major hallmarks of neurodegenerative diseases. Dysfunctional mitochondria accumulate in Alzheimer's disease-affected brains by yet unexplained mechanisms.

METHODS

We combined cell biology, molecular biology, and pharmacological approaches to unravel a novel molecular pathway by which presenilins control phosphatase and tensin homolog-induced kinase 1 (Pink-1) expression and transcription. In vivo approaches were carried out on various transgenic and knockout animals as well as in adeno-associated virus-infected mice. Functional readout and mitochondrial physiology (mitochondrial potential) were assessed by combined procedures including flow cytometry, live imaging analysis, and immunohistochemistry.

RESULTS

We show that presenilins 1 and 2 trigger opposite effects on promoter transactivation, messenger RNA, and protein expression of Pink-1. This control is linked to γ-secretase activity and β-amyloid precursor protein but is independent of phosphatase and tensin homolog. We show that amyloid precursor protein intracellular domain (AICD) accounts for presenilin-dependent phenotype and upregulates Pink-1 transactivation in cells as well as in vivo in a Forkhead box O3a-dependent manner. Interestingly, the modulation of γ-secretase activity or AICD expression affects Pink-1-related control of mitophagy and mitochondrial dynamics. Finally, we show that parkin acts upstream of presenilins to control Pink-1 promoter transactivation and protein expression.

CONCLUSIONS

Overall, we delineate a molecular cascade presenilins-AICD-Forkhead box O3a linking parkin to Pink-1. Our study demonstrates AICD-mediated Pink-1-dependent control of mitochondrial physiology by presenilins. Furthermore, it unravels a parkin-Pink-1 feedback loop controlling mitochondrial physiology that could be disrupted in neurodegenerative conditions.

How motivation and reward learning modulate selective attention

Motivational stimuli such as rewards elicit adaptive responses and influence various cognitive functions. Notably, increasing evidence suggests that stimuli with particular motivational values can strongly shape perception and attention. These effects resemble both selective top-down and stimulus-driven attentional orienting, as they depend on internal states but arise without conscious will, yet they seem to reflect attentional systems that are functionally and anatomically distinct from those classically associated with frontoparietal cortical networks in the brain. Recent research in human and nonhuman primates has begun to reveal how reward can bias attentional selection, and where within the cognitive system the signals providing attentional priority are generated. This review aims at describing the different mechanisms sustaining motivational attention, their impact on different behavioral tasks, and current knowledge concerning the neural networks governing the integration of motivational influences on attentional behavior.

Biodegradability of fluorinated fire-fighting foams in water

Fluorinated fire-fighting foams may be released into the environment during fire-fighting activities, raising concerns due to the potential environmental and health impacts for some fluorinated organics. The current study investigated (1) the biodegradability of three fluorinated fire-fighting foams, and (2) the applicability of current standard measures used to assess biodegradability of fluorinated fire-fighting foams. The biodegradability of three fluorinated fire-fighting foams was evaluated using a 28-day dissolved organic carbon (DOC) Die-Away Test. It was found that all three materials, diluted in water, achieved 77-96% biodegradability, meeting the criteria for "ready biodegradability". Defluorination of the fluorinated organics in the foam during biodegradation was measured using ion chromatography. It was found that the fluorine liberated was 1-2 orders of magnitude less than the estimated initial amount, indicating incomplete degradation of fluorinated organics, and incomplete CF bond breakage. Published biodegradability data may utilize biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) metrics to quantify organics. COD and TOC of four fluorinated compounds were measured and compared to the calculated carbon content or theoretical oxygen demand. It was found that the standard dichromate-based COD test did not provide an accurate measure of fluorinated organic content. Thus published biodegradability data using COD for fluorinated organics quantification must be critically evaluated for validity. The TOC measurements correlated to an average of 91% of carbon content for the four fluorinated test substances, and TOC is recommended for use as an analytical parameter in fluorinated organics biodegradability tests.

Plasma alkylresorcinols as a biomarker of whole-grain food consumption in a large population: results from the WHOLEheart Intervention Study

BACKGROUND

Small-scale, short-term intervention studies have suggested that plasma alkylresorcinol (AR) concentrations may be biomarkers of whole grain (WG) wheat and rye intakes.

OBJECTIVE

The objective was to determine whether plasma AR concentrations reflect self-reported WG food intake in a 16-wk WG intervention study and to establish which phenotypic characteristics influence plasma AR concentrations.

DESIGN

In a randomized parallel-group dietary intervention study, 316 overweight and obese participants with a WG intake of <30 g/d were recruited and randomly assigned to 1 of 3 groups: control (no dietary change), intervention 1 (60 g WG/d for 16 wk), or intervention 2 (60 g WG/d for 8 wk followed by 120 g WG/d for 8 wk). Fasting blood samples were collected at baseline, 8 wk, and 16 wk for the measurement of plasma lipids and ARs.

RESULTS

Plasma samples from 266 study completers were analyzed. Total plasma AR concentrations increased with the WG intervention and could be used to distinguish between control subjects and those who consumed 60 or 120 g WG, but not between those who consumed 60 and 120 g WG. Plasma AR concentrations were higher in men, were positively associated with plasma triglyceride concentrations, and were negatively associated with nonesterified fatty acids.

CONCLUSIONS

Plasma AR concentrations were correlated with WG intake and could be used to distinguish between low- and high-WG consumers. Sex and plasma lipid concentrations independently influenced plasma AR concentrations, although plasma triglycerides may explain higher concentrations in men. This trial is registered as ISRCT no. 83078872.

Lycopene bioavailability and metabolism in humans: an accelerator mass spectrometry study

BACKGROUND

To our knowledge, there is no direct information on lycopene metabolism in humans.

OBJECTIVE

The objective of this study was to quantify the long-term human bioavailability of lycopene in plasma and skin after a single dose of (14)C-lycopene and to profile the metabolites formed.

DESIGN

We preselected 2 male subjects as lycopene absorbers and gave them an oral dose of 10 mg synthetic lycopene combined with ≈6 μg [6,6',7,7'-(14)C]lycopene (≈30,000 Bq; 92% trans lycopene). The appearance of (14)C in plasma, plasma triacylglycerol-rich lipoprotein (TRL) fraction, urine, expired breath carbon dioxide, and skin biopsies was measured over 42 d. The (14)C in lycopene-isomer fractions from plasma and TRL fraction was measured to assess the isomerization of lycopene in vivo.

RESULTS

We quantified (14)C from (14)C-lycopene in plasma, the plasma TRL fraction, expired carbon dioxide, urine, and skin. The time to maximum concentration (t(max)) of total (14)C-lycopene in plasma was 6 h, and the elimination half-life (t(1/2)) was 5 d, which were different from the t(max) and t(1/2) of unlabeled lycopene (0.5 and 48 d, respectively). (14)C-Lycopene was extensively isomerized after dosing as a 92% all-trans isomer at dosing but changed to 50% trans, 38% 5 cis, 1% 9 cis, and 11% other cis isomers after 24 h. A similar pattern of isomerization was seen in plasma TRL fractions.

CONCLUSIONS

Lycopene was extensively isomerized after dosing and rapidly metabolized into polar metabolites excreted into urine with the rapid peak of (14)CO(2) after dosing, which implies that β-oxidation was involved in the lycopene metabolism. Lycopene or its metabolites were detected in skin for up to 42 d.

High rates of active hepatitis B and C co-infections in HIV-1 infected Cameroonian adults initiating antiretroviral therapy

OBJECTIVES

To investigate the presence of hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA in HIV-infected patients initiating antiretroviral therapy in Cameroon.

METHODS

Baseline blood samples from 169 patients were tested retrospectively for hepatitis B surface antigens (HBsAg), anti-hepatitis B core (anti-HBc), anti-HCV and - if HBsAg or anti-HCV result was positive or indeterminate - for HBV DNA or HCV RNA, respectively, using the Cobas Ampliprep/Cobas TaqMan quantitative assay (Roche Diagnostics GmbH, Mannheim, Germany).

RESULTS

HBV DNA was detected in 14 of the 18 patients with positive or indeterminate HBsAg results [8.3% of the total study population, 95% confidence interval (CI) 4.6-13.5]. The median HBV viral load was 2.47 x 10(7) IU/mL [interquartile range (IQR) 3680-1.59 x 10(8); range 270 to >2.2 x 10(8)]. Twenty-one patients (12.4%, 95% CI 7.9-18.4) were found with HCV RNA (all with positive HCV serology). The median HCV viral load was 928 000 IU/mL (IQR 178 400-2.06 x 10(6); range 640-5.5 x 10(6)). No patient was co-infected with HBV and HCV. In multivariate analysis, HCV co-infection was associated with greater age [>or=45 years vs. <45 years, odds ratio (OR) 11.89, 95% CI 3.49-40.55, P<0.001] and abnormal serum alanine aminotransferase level [>or=1.25 x upper limit of normal (ULN) vs. <1.25 x ULN, OR 7.81, 95% CI 1.54-39.66, P=0.01]; HBV co-infection was associated with abnormal serum aspartate aminotransferase level (OR 4.33, 95% CI 1.32-14.17, P=0.02).

CONCLUSIONS

These high rates of active HBV and HCV co-infections in HIV-positive Cameroonian patients requiring antiretroviral therapy underline the need to promote: (i) screening for HBV and HCV before treatment initiation; (ii) accessibility to tenofovir (especially in HBV-endemic African countries); and (iii) accessibility to treatment for HBV and HCV infections.

Dynamical mean field theory of an effective three-band model for NaxCoO2

We derive an effective Hamiltonian for highly correlated t_{2g} states centered at the Co sites of NaxCoO2. The essential ingredients of the model are an O mediated hopping, a trigonal crystal-field splitting, and on-site effective interactions derived from the exact solution of a multiorbital model in a CoO6 cluster, with parameters determined previously. The effective model is solved by dynamical mean field theory. We obtain a Fermi surface and electronic dispersion that agrees well with angle-resolved photoemission spectra. Our results also elucidate the origin of the "sinking pockets" in different doping regimes.

Gas chromatography/tandem mass spectrometry analysis of alkylresorcinols in red blood cells

Erythrocyte alkylresorcinols (5-alkyl-1,3-dihydroxybenzenes) are potential biomarkers of wholegrain wheat and rye intake. However, their high-throughput quantitative analysis by gas chromatography/mass spectrometry (GC/MS) is hindered by the time-consuming sample preparation and, more importantly, by interfering compounds that still remain after sample cleanup. In the present work we describe a gas chromatography/tandem mass spectrometry (GC/MS/MS) method for the rapid and reliable quantification of alkylresorcinols in erythrocyte samples. The performance of the GC/MS/MS method is compared with that of GC/MS. The main characteristics of the method are: lower limits of detection: 2-10 microg/L standard solution; lower limits of quantification: 6-30 microg/L standard solution; linearity coefficients: 0.9611-0.9888; linear ranges: 2-20 microg/L in erythrocytes; and intra-day precisions (n = 6): 4-13% at endogenous analyte levels in non-spiked erythrocytes. Tandem mass spectrometry showed greatly improved selectivity over single-stage mass spectrometry in the case of erythrocyte samples, eliminating all interferences detectable in single-stage MS and enabling simple peak integration for quantification. Moreover, increased selectivity resulted in GC separation speeded up by a factor of two, allowing the duplicate analysis of over 40 samples per day. This GC/MS/MS method is suggested as an improved alternative to GC/MS for the quantification of alkylresorcinols in erythrocytes for assessing wholegrain wheat and rye intake.

Metastases of clinically occult testicular seminoma mimicking primary extragonadal retroperitoneal germ cell tumors

BACKGROUND

Whether extragonadal germ cell tumors develop primarily in the retroperitoneum or whether they are essentially metastases of a primary testicular tumor has long been debated and remains controversial.

PATIENTS AND METHODS

Three patients presenting with apparent primary extragonadal retroperitoneal germ cell tumors are reported. Ipsilateral testicular evaluation was extended with palpation, ultrasonography and finally histological examination.

RESULTS

The retroperitoneal extragonadal tumors were found during abdominal MSCT. It was a fortuitous finding in the two first patients.The third patient presented with abdominal pain attributed to necrosis of the large mass which was subsequently firstly drained through endoscopic ultrasound-guided transduodenal puncture. The seminomatous nature of the retroperitoneal tumors was obtained through transduodenal echoendoscopic-guided cytopuncture in the first case, celioscopic resection in the second case and delayed percutaneous CT guided biopsy in the third symptomatic case. The first two patients had a history of cryptorchidism with substantial clinical testicular atrophy; ultrasonography showed microlithiasis and a small intratesticular tumor in the first patient and an hypoechoic but rather homogeneous atrophic testis in the other; orchiectomy confirmed small seminomatous intratesticular tumors in the two cases. The third patient had an atypical hypoechoic area on testicular ultrasound and histopatholgy revealed a burn-out primary tumor.

CONCLUSIONS

So-called primary extragonadal retroperitoneal germ cell tumors are extremely rare and should first be considered as metastases of a viable or burned-out testicular cancer until proven otherwise. All ipsilateral testicular abnormalities revealed by the patient's history, clinical examination and mostly by testicular ultrasound must be treated adequately with orchiectomy because they may act as a sanctuary for later tumor growth.

Feature extraction and signal processing for nylon DNA microarrays

Background

High-density DNA microarrays require automatic feature extraction methodologies and softwares. These can be a potential source of non-reproducibility of gene expression measurements. Variation in feature location or in signal integration methodology may be a significant contribution to the observed variance in gene expression levels.

Results

We explore sources of variability in feature extraction from DNA microarrays on Nylon membrane with radioactive detection. We introduce a mathematical model of the signal emission and derive methods for correcting biases such as overshining, saturation or variation in probe amount. We also provide a quality metric which can be used qualitatively to flag weak or untrusted signals or quantitatively to modulate the weight of each experiment or gene in higher level analyses (clustering or discriminant analysis).

Conclusions

Our novel feature extraction methodology, based on a mathematical model of the radioactive emission, reduces variability due to saturation, neighbourhood effects and variable probe amount. Furthermore, we provide a fully automatic feature extraction software, BZScan, which implements the algorithms described in this paper.

Characterization of a novel simian immunodeficiency virus from guereza colobus monkeys (Colobus guereza) in Cameroon: a new lineage in the nonhuman primate lentivirus family

Exploration of the diversity among primate lentiviruses is necessary to elucidate the origins and evolution of immunodeficiency viruses. During a serological survey in Cameroon, we screened 25 wild-born guereza colobus monkeys (Colobus guereza) and identified 7 with HIV/SIV cross-reactive antibodies. In this study, we describe a novel lentivirus, named SIVcol, prevalent in guereza colobus monkeys. Genetic analysis revealed that SIVcol was very distinct from all other known SIV/HIV isolates, with average amino acid identities of 40% for Gag, 50% for Pol, 28% for Env, and around 25% for proteins encoded by five other genes. Phylogenetic analyses confirmed that SIVcol is genetically distinct from other previously characterized primate lentiviruses and clusters independently, forming a novel lineage, the sixth in the current classification. Cercopithecidae monkeys (Old World monkeys) are subdivided into two subfamilies, the Colobinae and the Cercopithecinae, and, so far, all Cercopithecidae monkeys from which lentiviruses have been isolated belong to the Cercopithecinae subfamily. Therefore, SIVcol from guereza colobus monkeys (C. guereza) is the first primate lentivirus identified in the Colobinae subfamily and the divergence of SIVcol may reflect divergence of the host lineage.

Genetic diversity of protease and reverse transcriptase sequences in non-subtype-B human immunodeficiency virus type 1 strains: evidence of many minor drug resistance mutations in treatment-naive patients

Most human immunodeficiency virus (HIV) drug susceptibility studies have involved subtype B strains. Little information on the impact of viral diversity on natural susceptibility to antiretroviral drugs has been reported. However, the prevalence of non-subtype-B (non-B) HIV type 1 (HIV-1) strains continues to increase in industrialized countries, and antiretroviral treatments have recently become available in certain developing countries where non-B subtypes predominate. We sequenced the protease and reverse transcriptase (RT) genes of 142 HIV-1 isolates from antiretroviral-naive patients: 4 belonged to group O and 138 belonged to group M (9 subtype A, 13 subtype B, 2 subtype C, 5 subtype D, 2 subtype F1, 9 subtype F2, 4 subtype G, 5 subtype J, 2 subtype K, 3 subtype CRF01-AE, 67 subtype CRF02-AG, and 17 unclassified isolates). No major mutations associated with resistance to nucleoside reverse transcriptase inhibitors (NRTIs) or protease inhibitors were detected. Major mutations linked to resistance to non-NRTI agents were detected in all group O isolates (A98G and Y181C) and in one subtype J virus (V108I). In contrast, many accessory mutations were found, especially in the protease gene. Only 5.6% of the 142 strains, all belonging to subtype B or D, had no mutations in the protease gene. Sixty percent had one mutation, 22.5% had two mutations, 9.8% had three mutations, and 2.1% (all group O strains) had four mutations. In order of decreasing frequency, the following mutations were identified in the protease gene: M36I (86.6%), L10I/V (26%), L63P (12.6%), K20M/R (11.2%), V77I (5.6%), A71V (2.8%), L33F (0.7%), and M46I (0.7%). R211K, an accessory mutation associated with NRTI resistance, was also observed in 43.6% of the samples. Phenotypic and clinical studies are now required to determine whether multidrug-resistant viruses emerge more rapidly during antiretroviral therapy when minor resistance-conferring mutations are present before treatment initiation.

Most env and gag subtype A HIV-1 viruses circulating in West and West Central Africa are similar to the prototype AG recombinant virus IBNG

The genetic subtype was identified in gag and env of 219 HIV-1-positive samples collected in different African countries, 44 from Senegal, 55 from Cameroon, 82 from Gabon, and 38 from Djibouti. In total, 20 (9.1%) samples had discordant subtypes between gag and env, 6 of 44 (13.9%) in Senegal, 4 of 55 (7.2%) in Cameroon, 1 of 38 (2.6%) in Djibouti, and 10 of 82 (12.1%) in Gabon. Subtypes A and G were predominantly involved in the recombination events. Phylogenetic tree analysis of gag showed that an important number of the A sequences form a distinct subcluster with the AG-IBNG prototype strain (a complex A/G mosaic virus): 27 of 32 (84.3%) in Senegal, 12 of 17 (70.6%) in Nigeria, 24 of 39 (61.5%) in Cameroon, and 38 of 70 (54.3%) in Gabon. Full-length genome analysis of 3 and additional sequences in pol for 10 such strains confirmed that they have a similar complex A/G mosaic genomic structure. These data suggest that in West Africa, most probably between 60% and 84% of the subtype A viruses are recombinant AG-IBNG viruses. This finding has potential implications on future vaccine, diagnostic, and treatment strategies. The actual and future role of these viruses in the global pandemic must be monitored in all new molecular epidemiologic studies, a discrimination between subtype A and AG-IBNG-like viruses is necessary.

Near-full-length genome sequencing of divergent African HIV type 1 subtype F viruses leads to the identification of a new HIV type 1 subtype designated K

We recently reported a high divergence among African subtype F strains. Three well-separated groups (F1, F2, and F3) have been shown based on the phylogenetic analysis of the p24 gag and envelope sequences with genetic distances similar to those observed for known subtypes. In this study, we characterized the near-full-length genomes of two strains from epidemiological unlinked individual belonging to each of the subgroups: F1 (96FR-MP411), F2 (95CM-MP255 and 95CM-MP257), and F3 (96CM-MP535 and 97ZR-EQTB11). Phylogenetic analysis of the near-full-length sequences and for each of the genes separately showed the same three groups, supported by high bootstrap values. Diversity plotting, BLAST subtyping, and bootstrap plotting confirmed that the divergent F strains correspond to nonrecombinant viruses. The divergence between F1 and F2 is consistently lower than that seen in any other intersubtype comparison, with the exception of subtypes B and D. Based on all the different analyses, we propose to divide subtype F into two subclades, with F1 gathering the known subtype F strains from Brazil and Finland, and our African strain (96FR-MP411), and F2 containing the 95CM-MP255 and 95CM-MP257 strains from Cameroon. The F3 strains, 97ZR-EQTB11 from the Democratic Republic of Congo and 96CM-MP535 from Cameroon, meet the criteria of a new subtype designated as K. The equidistance of subtype K to the other subtypes of HIV-1 suggests that this subtype existed as long as the others, the lower distance between B and D, and between F1 and F2 suggest a more recent subdivision for these latter strains.

Characterization of a highly replicative intergroup M/O human immunodeficiency virus type 1 recombinant isolated from a Cameroonian patient

A Cameroonian patient with antibodies reacting simultaneously to human immunodeficiency virus type 1 (HIV-1) group O- and group M-specific V3-loop peptides was identified. In order to confirm that this patient was coinfected with both viruses, PCRs with O- and M-specific discriminating primers corresponding to different regions of the genome were carried out with both primary lymphocyte DNA and the corresponding viral strains isolated from three consecutive patient samples. The PCR data suggested that this patient is coinfected with a group M virus and a recombinant M/O virus. Indeed, only type M gag sequences could be amplified, while for the env region, both type M and O sequences were amplified, from plasma or from DNA extracted from primary lymphocytes. Sequence analysis of a complete recombinant genome isolated from the second sample (97CA-MP645 virus isolate) revealed two intergroup breakpoints, one in the vpr gene and the second in the long terminal repeat region around the TATA box. Comparison of the type M sequences shared by the group M and the recombinant M/O viruses showed that these sequences were closely related, with only 3% genetic distance, suggesting that the M virus was one of the parental viruses. In this report we describe for the first time a recombination event in vivo between viruses belonging to two different groups, leading to a replicative virus. Recombination between strains with such distant lineages (65% overall homology) may contribute substantially to the emergence of new HIV-1 variants. We documented that this virus replicates well and became predominant in vitro. At this time, group O viruses represent a minority of the strains responsible for the HIV-1 pandemic. If such recombinant intergroup viruses gained better fitness, inducing changes in their biological properties compared to the parental group O virus, the prevalences of group O sequences could increase rapidly. This will have important implications for diagnosis of HIV-1 infections by serological and molecular tests, as well as for antiviral treatment.

High diversity of HIV-1 subtype F strains in Central Africa

In this paper, we studied the variability of HIV-1 subtype F strains in Africa. For 11 viruses, mainly of Central African origin, different parts of the genome were genetically characterized. For all strains the V3-V5 region of the envelope gene was sequenced, and for 7 strains, the entire envelope gene was studied. For 10 strains, the p24 region of the gag gene was also sequenced. For each region studied, three subgroups in the F subtype were identified, F1, F2, and F3. These three subgroups were supported by high bootstrap values and the intra- and inter-subgroup F distances were comparable to those obtained for the known subtypes A, B, C, D, E, G, and H. In subgroup F1, some African strains clustered with previously described strains from Brazil and Romania, suggesting an African origin of the HIV-1 epidemic in these countries. A more detailed analysis of the gag and the envelope sequences allowed the identification of four recombinant viruses. Our data show a high diversity among subtype F strains, suggesting the presence of new subtypes in the regions studied. If biological differences exist among subtypes, it is important that these subtypes be well defined. The data from our study show that there is a need to clearly identify the different subgroups within the F subtype.

Prospective evaluation of a flow chart using a risk assessment for the diagnosis of STDs in primary healthcare centres in Libreville, Gabon

BACKGROUND

The serious impact of STDs on women and children in particular, and the linkage between STDs and HIV infection are a profound concern to public health worldwide. One of the main strategies against STDs is based on early diagnosis and treatment. However, this approach is limited by the lack of appropriate laboratory facilities. A syndromic approach has been recommended by the WHO but needs to be evaluated under field conditions. A preliminary cross sectional study on STD prevalence and risk factors in Libreville showed that 13.5% of pregnant women had gonococcal and/or chlamydial infection which justifies systematic screening of STDs. Based on the results of this study, different flow charts with or without a risk factor assessment (score) were designed. The flow chart with the best performances for diagnosing chlamydial or gonococcal cervical infection and routinely acceptable, was a score algorithm, based on two risk factors (age and marital status) and four simple clinical signs (pelvic or lumbar pain, vaginal discharge and its characteristics). Sensitivity and specificity were 76.9% and 40.4% respectively. Thus, the objective of this study was to evaluate this strategy under field conditions.

METHODS

A prospective study among pregnant women attending antenatal clinics was done. The score was applied to each woman by a midwife and a physician, and specimens were collected for the reference laboratory tests. Validation of the algorithm was done by comparing the performances with the gold standard laboratory diagnosis.

RESULTS

646 pregnant women were enrolled. The prevalence of cervical infection was 11.3. The sensitivity and specificity of this algorithm recorded by the midwives were 73.3% and 54.8%, respectively and by the physician 76.7% and 50.6%. The proportion of women correctly classified by the midwives and by the physician was not significantly different.

CONCLUSION

The score applied was well accepted by healthcare workers and patients, and was routinely practised. Results obtained by the midwives and by the physician were similar. Thus, the use of flow charts which adds a risk assessment to the syndromic approach for diagnosing cervical infections is feasible. However, the performances of such flow charts need to be improved before being used routinely.

Clinical algorithms for the screening of pregnant women for STDs in Libreville, Gabon: which alternatives?

OBJECTIVE

Sexually transmitted diseases (STDs) remain one of the major public health problems in the developing world. To implement a systematic screening of STDs among pregnant women in Libreville, Gabon, a preliminary cross sectional study on STD prevalence and risk factors was performed in antenatal clinics. A score, integrating risk factors and elementary clinical signs for the screening of STDs, showed higher performances compared with hierarchical algorithms. The prospective validation of this score based on six criteria (risk factors and simple clinical signs) was done in 1994-5. The sensitivity (76.7%), compared with results from other studies, was acceptable for diagnosing cervical infection (Neisseria gonorrhoeae and/or Chlamydia trachomatis) but the specificity was low (50.6%). In addition, the diagnostic values for diagnosing vaginal infection (Trichomonas vaginalis and/or Candida albicans) were poor. We then proposed to evaluate an alternative flowchart for the screening of cervical and vaginal infections.

METHODS

In this study, 646 pregnant women were enrolled. Each woman was interviewed and examined by a physician and then was subjected to reference laboratory examinations. An algorithm in two steps, combining a risk assessment score at the beginning of a hierarchical process, followed by a second step more specifically applied to a limited number of women, was developed and evaluated.

RESULTS

The prevalence rate was 11.3% for cervical infection and 39.5% for vaginal infection. The first step of the algorithm, applied to all pregnant women, is based on four criteria (age, marital status, dyspareunia, coloured vaginal discharge). It allows classification of the women into three classes: high, low, and intermediate risk of cervical infection. Only the patients with intermediate risk were submitted to further investigations including speculum and microscopic examination, and subsequently chlamydial antigen detection. This flowchart was 83.6% and 81.2% sensitive and 63.4% and 62.7% specific for predicting cervical infection and vaginal infection, respectively.

CONCLUSION

Similar strategies using simple rapid tests for chlamydial and gonococcal infection would certainly constitute a good diagnostic tool. This theoretical model needs to be evaluated prospectively, not only to confirm their diagnostic value but also to evaluate their feasibility, reliability and acceptability, as well as their cost effectiveness.

[Evaluation of the implementation of an educational curriculum: optimal interventions for the adoption of an educational program of health in elementary schools]

A multiple case study design is used to explain the level of implementation of a "Heart Health" curriculum by grade four teachers of eight schools in a Montreal multiethnic and underprivileged district. An interview and logbook examine the following variables: 1) personal characteristics of the teachers; 2) organizational characteristics of the schools; 3) characteristics of the program; 4) collaboration between the health and educational sectors; and 5) curriculum level of use and fidelity of implementation. The results show in particular that the personal characteristics of the teachers and the characteristics of the program explain the level of implementation of the Heart Health curriculum.

[Evaluation of the implementation of an educational curriculum: optimal interventions for the adoption of an educational program of health in elementary schools]

A multiple case study design is used to explain the level of implementation of a "Heart Health" curriculum by grade four teachers of eight schools in a Montreal multiethnic and underprivileged district. An interview and logbook examine the following variables: 1) personal characteristics of the teachers; 2) organizational characteristics of the schools; 3) characteristics of the program; 4) collaboration between the health and educational sectors; and 5) curriculum level of use and fidelity of implementation. The results show in particular that the personal characteristics of the teachers and the characteristics of the program explain the level of implementation of the Heart Health curriculum.