Synergies of THESEUS with the large facilities of the 2030s and guest observer opportunities.

The proposed THESEUS mission will vastly expand the capabilities to monitor the high-energy sky. It will specifically exploit large samples of gamma-ray bursts to probe the early universe back to the first generation of stars, and to advance multi-messenger astrophysics by detecting and localizing the counterparts of gravitational waves and cosmic neutrino sources. The combination and coordination of these activities with multi-wavelength, multi-messenger facilities expected to be operating in the 2030s will open new avenues of exploration in many areas of astrophysics, cosmology and fundamental physics, thus adding considerable strength to the overall scientific impact of THESEUS and these facilities. We discuss here a number of these powerful synergies and guest observer opportunities.

Amyloid and tau pathology of familial Alzheimer's disease APP/PS1 mouse model in a senescence phenotype background (SAMP8).

The amyloid precursor protein/presenilin 1 (APP/PS1) mouse model of Alzheimer's disease (AD) has provided robust neuropathological hallmarks of familial AD-like pattern at early ages, whereas senescence-accelerated mouse prone 8 (SAMP8) has a remarkable early senescence phenotype with pathological similarities to AD. The aim of this study was the investigation and characterization of cognitive and neuropathological AD markers in a novel mouse model that combines the characteristics of the APP/PS1 transgenic mouse model with a senescence-accelerated background of SAMP8 mice. Initially, significant differences were found regarding amyloid plaque formation and cognitive abnormalities. Bearing these facts in mind, we determined a general characterization of the main AD brain molecular markers, such as alterations in amyloid pathway, neuroinflammation, and hyperphosphorylation of tau in these mice along their lifetimes. Results from this analysis revealed that APP/PS1 in SAMP8 background mice showed alterations in the pathways studied in comparison with SAMP8 and APP/PS1, demonstrating that a senescence-accelerated background exacerbated the amyloid pathology and maintained the cognitive dysfunction present in APP/PS1 mice. Changes in tau pathology, including the activity of cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3 ß (GSK3ß), differs, but not in a parallel manner, with amyloid disturbances.

Dissecting x-ray-emitting gas around the center of our galaxy.

Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides an instructive exception, and we present a close-up view of its quiescent x-ray emission based on 3 megaseconds of Chandra observations. Although the x-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission on the basis of the lack of predicted iron (Fe) Kα emission. The extremely weak hydrogen (H)-like Fe Kα line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.

Decrease of calbindin-d28k, calretinin, and parvalbumin by taurine treatment does not induce a major susceptibility to kainic acid.

Taurine, 2-aminoethanesulfonic acid, is present at high concentrations in many invertebrate and vertebrate systems, and it has several biological functions. In addition, it has been related to a neuroprotective role against several diseases, such as epilepsy. It has been reported that taurine induces a decrease of calbindin-D28k, calretinin, and parvalbumin protein levels in the hippocampus 3 days after administration. In the present work we hypothesized that the decrease of these proteins could alter the action of kainic acid (KA) and make mice more susceptible to excitotoxicity. Therefore, we treated mice with taurine and after 3 days treated them with KA. The results showed that taurine pretreatment did not induce a major susceptibility to KA. Moreover, neurodegeneration was reduced in pretreated mice. However, astrogliosis was similar to that observed in mice treated only with KA. The immunohistochemistries for calbindin-D28k, calretinin, and parvalbumin showed that these proteins were reduced as a consequence of KA treatment and of taurine treatment. However, mice pretreated with taurine prior to KA administration presented the same reduction in these proteins as mice treated with only taurine or only KA.

Serum hyperglycosylated human chorionic gonadotropin to predict the gestational outcome in in vitro fertilization/intracytoplasmic sperm injection pregnancies.

Hyperglycosylated human chorionic gonadotropin (H-hCG) is secreted by the placenta in early pregnancy. Decreased H-hCG levels have been associated with abortion in spontaneous pregnancy. We retrospectively measured H-hCG and dimeric hCG in the sera of 87 in vitro fertilization patients obtained in the 3 weeks following embryo transfer and set the results in relation to pregnancy outcome. H-hCG and dimeric hCG were correlated (r(2) = 0.89), and were significantly decreased in biochemical pregnancy (2 microg/l and 18 IU/l, respectively) compared to early pregnancy loss (22 microg/l and 331 IU/l) and ongoing pregnancy (32 microg/l and 353 IU/l). Only H-hCG tended to discriminate between these last two groups.

[Haemolysis and turbidity influence on three analysis methods of quantitative determination of total and conjugated bilirubin on ADVIA 1650]. / Interférences de l'hémolyse et de la lipémie sur trois méthodes de dosage de la bilirubine totale et conjuguée sur ADVIA 1650.

Plasma bilirubin testing is crucial to prevent the occurrence of neonatal kernicterus. Haemolysis may occur during sampling and interfere with bilirubin determination. Moreover, lipidic infusions may induce plasma lipemia and also interfere with bilirubin measurement. We evaluated the interference of haemolysis and lipemia with three methods of total and direct bilirubin measurement adaptated on an Advia 1650 analyser (Siemens Medical Solutions Diagnostics) : Synermed (Sofibel), Bilirubin 2 (Siemens) and Bilirubin Auto FS (Diasys). The measurement of total bilirubin was little affected by haemolysis with all three methods. The Bilirubin 2 (Siemens) method was the less sensitive to haemolysis even at low bilirubin levels. The measurement of conjugated bilirubin was significantly altered by low heamoglobin concentrations for Bilirubin Auto FS(R) (30 microM or 0,192 g/100 mL haemoglobin) and for Synermed (60 microM or 0,484 g/100 mL haemoglobin). In marked contrast, we found no haemoglobin interference with the Direct Bilirubin 2 reagent which complied with the method validation criteria from the French Society for Biological Chemistry. The lipemia up to 2 g/L of Ivelip did not affect neither the measurement of total bilirubin for all three methods nor the measurement of conjugated bilirubin with the Diasys and Siemens reagents. However, we observed a strong interference starting at 0,5 g/L of Ivelip with the Synermed reagent. Our data suggest that both Siemens and Diasys methods allow to measure accurately total and conjugated bilirubin in hemolytic and lipemic samples, nevertheless, the Siemens methodology is less affected by these interferences.

[Biologic tests for the diagnosis of amniotic fluid embolism]. / Dépistage de l'embolie amniotique: vers un test diagnostique ?

Amniotic fluid embolism is a rare, unpredictable and often lethal complication of pregnancy and childbirth. Because of its variable presentation, an early biologic test would help to establish the diagnosis. We investigated in maternal serum 4 components of amniotic fluid, i.e., alpha-fetoprotein (AFP), l'insuline like growth factor binding protein-1 (IGFBP-1), fetal fibronectin (fFN) and placental alpha1-microglobulin (PAMG-1). On the 6 cesareans controls involved, none of the makers increased after membranes section. PAMG-1 is unsuitable because its detection is always positive or doubtful even in the baseline. On the 7 cases suspected of amniotic fluid embolism, no detectable increase in any of those markers was noted in 3 cases, which is not in favour of this diagnosis. In the remaining cases, IGFBP-1 and fFN became detectable, confirming histological evidences of amniotic fluid embolism in 2 cases. The follow up of those markers in maternal blood confirmed the suspicion of amniotic fluid embolism at 21 wg in one case of ongoing pregnancy. These preliminary results point out the potential interest to assay maternal serum AFP, IGFBP-1 and fFN to confirm amniotic fluid embolism using rapid laboratory tests.

[Recommendations for the standardization of growth hormone assays]. / Recommandations pour l'harmonisation des techniques de dosage sérique d'hormone de croissance.

The diagnosis of growth hormone (GH) deficiency is based on the GH biological response to pharmacological stimulation tests. The cut-off value defining normality is the same whatever the GH assay used. In a group of the French Society for Clinical Biology (SFBC), we have evaluated whether differences between the GH concentrations obtained with the 9 commercial GH assays available in France exist or not. The study samples consisted of 72 serum pools and serial dilutions of the recombinant GH 22 kDa international standard, IS 98/574. These dilutions were performed by using 3 different diluents: the specific diluent provided by the manufacturers and thus different from one assay to another, serum without GH and heparin plasma without GH. Despite being calibrated against the same international standard, the different assays proposed variable conversion factors between microg and mIU, and we decided to express the results in mIU. The GH concentrations obtained for the 72 serum pools with the 9 assays were highly correlated, but absolute concentrations were significantly different from one assay to another. In particular, the ratio between the concentrations measured with both assays giving the lowest and highest concentration in the same sample respectively was about 50%. In the recovery test executed by adding the international standard, the slope of the regression curve describing the relationship between expected and measured concentrations was different of 1 in all but one assay. Furthermore, for a given assay and a given expected concentration, the measured values were sometimes different by up to 30% depending on the diluent used. These results led us to advise the manufacturers to calibrate their assays against the recombinant GH international standard, IS 98/574, to take into account the matrix effect detected in our study and to use the official conversion factor of 3 mIU/microg. Waiting for this new calibration, it is recommended that the results should be expressed in mIU/L and that serum samples should be used for the measurement of GH instead of plasma samples.

Trophoblast production of a weakly bioactive human chorionic gonadotropin in trisomy 21-affected pregnancy.

Total human chorionic gonadotropin (hCG) is high in maternal serum at 14-18 wk of trisomy 21 (T21)-affected pregnancy, despite low placental hCG synthesis. We sought an explanation for this paradox. We first observed that, in T21-affected pregnancies, maternal serum hCG levels peaked at around 10 wk and then followed the same pattern throughout pregnancy as in controls, albeit at a higher (2.2-fold) level. After delivery, hCG clearance was not significantly different from that in controls. We isolated cytotrophoblasts from 29 T21-affected placentas (12-25 wk) and 13 gestational age-matched control placentas and cultured them for 3 d. In this large series, we confirmed that, in the culture medium of trophoblasts isolated from T21 placentas, hCG secretion was significantly lower (P < 0.003) than in controls, in contrast to the high hCG in maternal serum of the same patients. In T21 cultured trophoblasts, transcripts of sialyltransferase-1 and fucosyltransferase-1 were abnormally high. In corresponding culture medium, hCG was abnormally glycosylated; highly acidic [isoelectric points (pHi) = 4.5] as shown by isoelectric focusing, immunoblotting, and lectin binding; and weakly bioactive (46% of control) as determined using the Leydig cell model. In conclusion, T21 trophoblast cells produced hCG that was weakly bioactive and abnormally glycosylated but whose maternal clearance was unaltered.

Anti-Müllerian hormone levels in serum from human foetuses and children: pattern and clinical interest.

Serum anti-Müllerian hormone (AMH) determination has been used to investigate gonadal development and abnormal sexual differentiation, but until recently, it was based on assays developed by specialized laboratories. A short time ago, a sensitive assay kit was developed commercially (Immunotech-Beckman Coulter) for clinical use. With this method, we established usual levels of serum AMH in fetuses, newborns, and pre-pubertal children, and evaluated the clinical value of this assay. AMH measurement required only 25 microl of sample and could be performed within 3 h. In females, AMH emerged after birth at low levels (median: 4 ng/ml). In males, AMH levels remained stable during fetal life (median: 44.4 ng/ml), peaked in the first months of life to reach a median of 124.7 ng/ml, then fell with wide individual variations. Cord blood AMH levels at birth may be useful to investigate ambiguous genitalia suspected prenatally. In children with isolated microphallus or hypospadias, decreased AMH values are in favor of testis dysfunction. When testes cannot be palpated, a single determination of serum AMH levels can distinguish between anorchia and cryptorchidism.

Expression of pregnancy-associated plasma protein-A (PAPP-A) during human villous trophoblast differentiation in vitro.

Pregnancy-associated placental protein-A (PAPP-A), first isolated from maternal serum, has been identified as a metalloprotease cleaving insulin-like growth factor binding protein-4 (IGFBP-4). The source of PAPP-A during pregnancy is unclear. We therefore investigated PAPP-A expression during in vitro human villous cytotrophoblast cell (CT) differentiation into syncytiotrophoblast (ST). CT were isolated from normal first trimester, second trimester and term placentae (n=10) and cultured to form ST. PAPP-A mRNA was quantified by real-time PCR, and PAPP-A protein expression was studied by immunocytochemistry and TRACE technology with specific monoclonal antibodies. PAPP-A mRNA expression in total placental extracts increased during the course of pregnancy. PAPP-A protein was detected in the cytoplasm of both CT and ST. ST formation in vitro was associated with a 19-fold increase in PAPP-A mRNA expression and an 8-fold increase in PAPP-A secretion into the culture medium. No significant difference in PAPP-A production was observed between cultured cells isolated from early and term placentae. In conclusion, PAPP-A production in vitro, is associated to the differentiation of villous cytotrophoblast cells into syncytiotrophoblast, independently of the age of gestation.

Biochemical investigation of foetal and neonatal thyroid function using the ACS-180SE analyser: clinical application.

Despite sonographic detection of foetal goitre, uncertainty persists in the initial diagnosis of thyrotoxicosis and hypothyroidism. The aim of this study was to establish foetal and neonatal iodothyronine and thyrotrophin reference values for the ACS-180SE analyser. From 22 to 36 weeks of gestation, median foetal serum free thyroxine (FT4) levels increased from 6.0 pmol/L to 143 pmol/L, while free tri-iodothyronine (FT3) levels increased from 0.7 pmol/L to 1.9 pmol/L and mean thyrotrophin (TSH) levels remained stable (10.2 +/- 3.8mU/L; n = 33). At birth, concentrations were independent of gender and gestational age. Among the 10 cases of sonographically detected foetal goitre, serum TSH and FT4 were measured in five, showing hypothyroidism (3/5) or hyperthyroidism (2/5). Cord blood TSH levels reflected the efficacy of prenatal therapy. Measurement of foetal FT4 and TSH can be used to confirm foetal thyroid dysfunction, whereas treatment efficacy can be assessed sonographically and confirmed by measurement of TSH assay at birth.

[Placental hormones and fetal growth]. / Hormones placentaires et croissance foetale.

Fetal growth is controlled by the placenta which mediates fetal nutritional supplies. During pregnancy, the placenta secretes a specific placental growth hormone which replaces the pituitary growth hormone in the maternal circulation. Placental growth hormone is one example of the materno-placental cooperation which is impaired in cases of intra-uterine growth retardation.

Utility of insulin-like growth factor-I and its binding protein assays.

Insulin-like growth factor-I circulates in serum either in free form or bound to insulin-like growth factor-binding proteins that modulate its bioavailability. Insulin-like growth factor-binding proteins interfere with insulin-like growth factor-I assay, which remains technically difficult. Many assays have been developed, but their results are somewhat discordant. The choice of separation method, standard and tracer considerably influences the results. The circulating concentration of insulin-like growth factor-I, however, is clearly dependent on nutritional status, and total levels are a valuable marker of nutritional status. The clinical utility of free insulin-like growth factor-I assay and simultaneous assay, in the same sample, of total insulin-like growth factor-I and its binding proteins (reflecting the bioavailable insulin-like growth factor-I fraction), remains to be evaluated.

N219Y, a new frequent mutation among mut(degree) forms of methylmalonic acidemia in Caucasian patients.

Mutations in the MUT locus encoding for the methylmalonyl-CoA mutase (MCM) apoenzyme are responsible for the mut forms of methylmalonic acidemia (MMA). To date, 49 different mutations have been identified in mut MMA. Only two frequent mutations have been reported in the Japanese population and in African-Americans. Here we report a new missense mutation N219Y (731 A-->T) which we found in five unrelated families of French and Turkish descent. All the patients exhibited a severe mut(degree) phenotype and three of them were homozygotes for N219Y. Direct involvement of the mutation in the loss of enzyme activity was demonstrated by mutagenesis and transient expression study. Mapping of the mutation onto a three-dimensional model of human MCM constructed by homology with the Propionibacterium shermanii enzyme shows that it lies in a highly conserved secondary structure motif and might suggest impaired folding and/or poor stability compatible with the mut(degree) phenotype. Finally, a 1% N219Y carrier frequency was observed in a French anonymous control population. Thus, N219Y is the first frequent mut mutation to be reported in the Caucasian population.

Establishment of reference values of five amniotic fluid enzymes. Analytical performances of the Hitachi 911. Application to complicated pregnancies.

OBJECTIVES: to evaluate the analytical performances of the Hitachi 911 analyzer (Roche Diagnostics, F) for gamma-glutamyl-transferase, 5'nucleotidase, amylase, aspartate-amino-transferase and total-alkaline-phosphatase assay in amniotic fluid. To establish reference intervals for these five enzymes throughout gestation. To determine their antenatal diagnostic value. DESIGN AND METHODS: amniotic fluid samples were collected between 14 and 35 weeks of gestation. Weekly numbers ranged from 31 to 92. Techniques developed for serum enzyme assays were applied to amniotic fluid. Two pools of amniotic fluid containing low and high marker levels were used. Within-day and between-day variations were calculated, together with the limits of detection and linearity. Reference ranges were established on 508 amniotic fluid samples, including 23 samples from pregnancies with chromosomal aberrations, 14 with gastrointestinal tract defects and 5 with gastroschisis. RESULTS: the assay technique for total-alkaline-phosphatase assay had to be adapted to amniotic fluid, but no adaptation was necessary for the other markers. The within-day CV ranged between 2.2 and 11.2% for low-level samples and from 1.1 to 3.4% for high-level samples. The between-day CV ranged from 6.3 to 13.3% for low-level samples and 1.2 to 4.7% for high-level samples. Total-alkaline-phosphatase activity fluctuated throughout gestation. Amylase levels and aspartate-amino-transferase levels increased whereas gamma-glutamyl-transferase and 5'nucleotidase levels fell until delivery. All trisomy 18 and trisomy 13 pregnancies, 65% of Down's syndrome pregnancies and all pregnancies with digestive tract defects were associated with marked changes in the level of at least one enzyme. CONCLUSION: The Hitachi 911 is suited to rapid, reliable quantification of amniotic fluid enzymes with only minor adaptation. Useful reference intervals can be obtained throughout gestation. Gamma-glutamyl-transferase, 5'nucleotidase, total-alkaline-phosphatase and amylase assay can help to confirm echographic evidence of bowel disorders and thereby improve patient management especially in case of gastroschisis.

Molecular and structural analysis of two novel mutations in a patient with mut(-) methylmalonyl-CoA deficiency.

Inherited defects in the gene encoding the methylmalonyl-CoA mutase (MCM) result in the mut forms of methylmalonic aciduria (MMA). Twelve mutations have been identified associated with the mut(-) phenotype. We report two novel mutations (K621N and D156N) in a compound heterozygote mut(-) patient. These two mutations and three previously published ones (H627N, A191E, Y231N) were mapped onto a three-dimensional homology model of the human MCM constructed from the crystal structure of the Propionibacterium shermanii enzyme.

Alpha-1-acid glycoprotein.

Alpha-1-acid glycoprotein (AGP) or orosomucoid (ORM) is a 41-43-kDa glycoprotein with a pI of 2.8-3.8. The peptide moiety is a single chain of 183 amino acids (human) or 187 amino acids (rat) with two and one disulfide bridges in humans and rats,respectively. The carbohydrate content represents 45% of the molecular weight attached in the form of five to six highly sialylated complex-type-N-linked glycans. AGP is one of the major acute phase proteins in humans, rats, mice and other species. As most acute phase proteins, its serum concentration increases in response to systemic tissue injury, inflammation or infection, and these changes in serum protein concentrations have been correlated with increases in hepatic synthesis. Expression of the AGP gene is controlled by a combination of the major regulatory mediators, i.e. glucocorticoids and a cytokine network involving mainly interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF alpha), interleukin-6 and IL-6 related cytokines. It is now well established that the acute phase response may take place in extra-hepatic cell types, and may be regulated by inflammatory mediators as observed in hepatocytes. The biological function of AGP remains unknown; however,a number of activities of possible physiological significance, such as various immunomodulating effects, have been described. AGP also has the ability to bind and to carry numerous basic and neutral lipophilic drugs from endogenous (steroid hormones) and exogenous origin; one to seven binding sites have been described. AGP can also bind acidic drugs such as phenobarbital. The immunomodulatory as well as the binding activities of AGP have been shown to be mostly dependent on carbohydrate composition. Finally, the use of AGP transgenic animals enabled to address in vivo, functionality of responsive elements and tissue specificity, as well as the effects of drugs that bind to AGP and will be an useful tool to determine the physiological role of AGP.