Cu2+-binding to S100B triggers polymerization of disulfide cross-linked tetramers with enhanced chaperone activity against amyloid-β aggregation

S100B is an extracellular protein implicated in Alzheimer's Disease and a suppressor of amyloid-β aggregation. Herein we report a mechanism tying Cu2+ binding to a change in assembly state yielding disulfide cross-linked oligomers with higher anti-aggregation activity. This chemical control of chaperone function illustrates a regulatory process relevant under metal and proteostasis dysfunction as in neurodegeneration.

Receptor for Advanced Glycation End Products is Involved in Platelet Hyperactivation and Arterial Thrombosis during Chronic Kidney Disease

BACKGROUND

 Chronic kidney disease (CKD) is associated with a high cardiovascular mortality due to increased rates of vascular lesions and thrombotic events, as well as serum accumulation of uremic toxins. A subgroup of these toxins (advanced glycation end products [AGEs] and S100 proteins) can interact with the receptor for AGEs (RAGE). In this study, we analyzed the impact of CKD on platelet function and arterial thrombosis, and the potential role of RAGE in this process.

METHODS

 Twelve weeks after induction of CKD in mice, platelet function and time to complete carotid artery occlusion were analyzed in four groups of animals (sham-operated, CKD, apolipoprotein E [Apoe]^-/-, and Apoe^-/-/Ager^-/- mice).

RESULTS

 Analysis of platelet function from whole blood and platelet-rich plasma showed hyperactivation of platelets only in CKD Apoe^-/- mice. There was no difference when experiments were done on washed platelets. However, preincubation of such platelets with AGEs or S100 proteins induced RAGE-mediated platelet hyperactivation. In vivo, CKD significantly reduced carotid occlusion times of Apoe^-/- mice (9.2 ± 1.1 vs. 11.1 ± 0.6 minutes for sham, p < 0.01). In contrast, CKD had no effect on occlusion times in Apoe^-/-/Ager^-/- mice. Moreover, carotid occlusion in Apoe^-/- CKD mice occurred significantly faster than in Apoe^-/-/Ager^-/- CKD mice (p < 0.0001).

CONCLUSION

 Our results show that CKD induces platelet hyperactivation, accelerates thrombus formation in a murine model of arterial thrombosis, and that RAGE deletion has a protective role. We propose that RAGE ligands binding to RAGE is involved in CKD-induced arterial thrombosis.

Prothrombin is a binding partner of the human receptor of advanced glycation end products

The receptor for advanced glycation end products (RAGE) plays a key role in mammal physiology and in the etiology and progression of inflammatory and oxidative stress-based diseases. In adults, RAGE expression is normally high only in the lung where the protein concentrates in the basal membrane of alveolar Type I epithelial cells. In diseases, RAGE levels increase in the affected tissues and sustain chronic inflammation. RAGE exists as a membrane glycoprotein with an ectodomain, a transmembrane helix, and a short carboxyl-terminal tail, or as a soluble ectodomain that acts as a decoy receptor (sRAGE). VC1 domain is responsible for binding to the majority of RAGE ligands including advanced glycation end products (AGEs), S100 proteins, and HMGB1. To ascertain whether other ligands exist, we analyzed by MS the material pulled down by VC1 from human plasma. Twenty of 295 identified proteins were selected and associated to coagulation and complement processes and to extracellular matrix. Four of them contained a γ-carboxyl glutamic acid (Gla) domain, a calcium-binding module, and prothrombin (PT) was the most abundant. Using MicroScale thermophoresis, we quantified the interaction of PT with VC1 and sRAGE in the absence or presence of calcium that acted as a competitor. PT devoid of the Gla domain (PT des-Gla) did not bind to sRAGE, providing further evidence that the Gla domain is critical for the interaction. Finally, the presence of VC1 delayed plasma clotting in a dose-dependent manner. We propose that RAGE is involved in modulating blood coagulation presumably in conditions of lung injury.

A capture method based on the VC1 domain reveals new binding properties of the human receptor for advanced glycation end products (RAGE)

The Advanced Glycation and Lipoxidation End products (AGEs and ALEs) are a heterogeneous class of compounds derived from the non-enzymatic glycation or protein adduction by lipoxidation break-down products. The receptor for AGEs (RAGE) is involved in the progression of chronic diseases based on persistent inflammatory state and oxidative stress. RAGE is a pattern recognition receptor (PRR) and the inhibition of the interaction with its ligands or of the ligand accumulation have a potential therapeutic effect. The N-terminal domain of RAGE, the V domain, is the major site of AGEs binding and is stabilized by the adjacent C1 domain. In this study, we set up an affinity assay relying on the extremely specific biological interaction AGEs ligands have for the VC1 domain. A glycosylated form of VC1, produced in the yeast Pichia pastoris, was attached to magnetic beads and used as insoluble affinity matrix (VC1-resin). The VC1 interaction assay was employed to isolate specific VC1 binding partners from in vitro generated AGE-albumins and modifications were identified/localized by mass spectrometry analysis. Interestingly, this method also led to the isolation of ALEs produced by malondialdehyde treatment of albumins. Computational studies provided a rational-based interpretation of the contacts established by specific modified residues and amino acids of the V domain. The validation of VC1-resin in capturing AGE-albumins from complex biological mixtures such as plasma and milk, may lead to the identification of new RAGE ligands potentially involved in pro-inflammatory and pro-fibrotic responses, independently of their structures or physical properties, and without the use of any covalent derivatization process. In addition, the method can be applied to the identification of antagonists of RAGE-ligand interaction.

•

A new VC1 interaction affinity assay was validated using model AGE-albumins.

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In vitro modifications of the interacting partners were identified/localized by MS.

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The VC1-pull down assays captures AGE-albumins in simulated complex mixtures

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ALEs produced by malondialdehyde treatment were mapped in VC1-interacting albumins.

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The molecular interactions of MDA-induced adduct-VC1 complexes were rationalized.

[Accuracy of placenta accreta prenatal diagnosis by ultrasound and MRI in a high-risk population]

OBJECTIVES

Main objective was to compare accuracy of ultrasonography and MRI for antenatal diagnosis of placenta accreta. Secondary objectives were to specify the most common sonographic and RMI signs associated with diagnosis of placenta accreta.

MATERIAL AND METHODS

This retrospective study used data collected from all potential cases of placenta accreta (patients with an anterior placenta praevia with history of scarred uterus) admitted from 01/2010 to 12/2014 in a level III maternity unit in Strasbourg, France. High-risk patients beneficiated antenatally from ultrasonography and MRI. Sonographic signs registered were: abnormal placental lacunae, increased vascularity on color Doppler, absence of the retroplacental clear space, interrupted bladder line. MRI signs registered were: abnormal uterine bulging, intraplacental bands of low signal intensity on T2-weighted images, increased vascularity, heterogeneous signal of the placenta on T2-weighed, interrupted bladder line, protrusion of the placenta into the cervix. Diagnosis of placenta accreta was confirmed histologically after hysterectomy or clinically in case of successful conservative treatment.

RESULTS

Twenty-two potential cases of placenta accreta were referred to our center and underwent both ultrasonography and MRI. All cases of placenta accreta had a placenta praevia associated with history of scarred uterus. Sensibility and specificity for ultrasonography were, respectively, 0.92 and 0.67, for MRI 0.84 and 0.78 without significant difference (p>0.05). The most relevant signs associated with diagnosis of placenta accreta in ultrasonography were increased vascularity on color Doppler (sensibility 0.85/specificity 0.78), abnormal placental lacunae (sensibility 0.92/specificity 0.55) and loss of retroplacental clear space (sensibility 0.76/specificity 1.0). The most relevant signs in MRI were: abnormal uterine bulging (sensitivity 0.92/specificity 0.89), dark intraplacental bands on T2-weighted images (sensitivity 0.83/specificity 0.80) or placental heterogeneity (sensitivity 0.92/specificity 0.89). Association of two sonographic or MRI signs had the best sensitivity/specificity ratio.

DISCUSSION AND CONCLUSION

Ultrasonography and RMI represent two interesting and complementary diagnostic tools for antenatal diagnosis of placenta accreta. Because of its cost and accessibility, ultrasonography remains the first in line to be used for diagnosis. Use of an analytical grid for diagnosis of placenta accreta could be helpful.

An improved expression system for the VC1 ligand binding domain of the receptor for advanced glycation end products in Pichia pastoris

The receptor for the advanced glycation end products (RAGE) is a type I transmembrane glycoprotein belonging to the immunoglobulin superfamily and binds a variety of unrelated ligands sharing a negative charge. Most ligands bind to the extracellular V or VC1 domains of the receptor. In this work, V and VC1 of human RAGE were produced in the methylotrophic yeast Pichia pastoris and directed to the secretory pathway. Fusions to a removable C-terminal His-tag evidenced proteolytic processing of the tag by extracellular proteases and also intracellular degradation of the N-terminal portion of V-His. Expression of untagged forms was attempted. While the V domain was retained intracellularly, VC1 was secreted into the medium and was functionally active in binding AGEs. The glycosylation state of VC1 was analyzed by mass spectrometry and peptide-N-glycosidase F digestion. Like RAGE isolated from mammalian sources, the degree of occupancy of the N-glycosylation sites was full at Asn25 and partial at Asn81 which was also subjected to non-enzymatic deamidation. A simple procedure for the purification to homogeneity of VC1 from the medium was developed. The folded state of the purified protein was assessed by thermal shift assays. Recombinant VC1 from P. pastoris showed a remarkably high thermal stability as compared to the protein expressed in bacteria. Our in vivo approach indicates that the V and C1 domains constitute a single folding unit. The stability and solubility of the yeast-secreted VC1 may be beneficial for future in vitro studies aimed to identify new ligands or inhibitors of RAGE.

[Twin pregnancy with complete hydatiform mole and coexistent fetus: Report of 4 cases and review of literature]

OBJECTIVE

Twin pregnancy with complete hydatiform mole and coexistent fetus is a rare clinical condition, occurring in 1 in 22,000 to one in 100,000 pregnancies. Continuation of pregnancy in these cases is controversial because of a high risk of immediate and long-term maternal morbidity. It allows, however, in 33 % of the case the delivery of a healthy child.

METHODS

This retrospective study included all patients presenting a complete hydatiform mole coexisting with a live twin fetus antenatally diagnosed between 2007 and 2012 in the level III maternity of the Strasbourg University Hospital. Informations concerning diagnostic circumstances, pregnancy follow-up and outcome were studied.

RESULTS

Four pregnancies were included in the study, all of them were spontaneous. Medical termination of pregnancies was related to maternal reasons in the four cases. One before 17 weeks of gestation, the three other after 2 weeks of gestation, leading to delivery of a healthy child. All patients developed a mild to severe preeclampsia. One patient developed a gestational trophoblastic disease, requiring chemotherapy by methotrexate. There was no fatal evolution.

CONCLUSION

Twin pregnancy with complete hydatifom mole and coexistent fetus is associated with increased risk of gestational trophoblastic disease. This risk is not increased by continuation of pregnancy. In case of prenatal diagnosis of complete hydatiform mole coexisting with a live twin fetus, patients should be aware of the potential high risk of morbidity and a regular follow-up during and after the pregnancy should be intaured. In absence of maternal complications, continuation of the pregnancy is possible.

[A rare case of caudal appendage]

Caudal appendage is a rare malformation which has since ever been interesting. We present the case of a girl in which a caudal appendage was discovered before birth. A throughout checking found an extension from this abnormality to the cordal spine. The baby is operated when 2months old. Differential diagnosis are spina bifida, teratoma and pilonidal sinus. Caudal appendage is one of the typical cutaneous finding with underlying spinal dysraphism, such as hair tuft or pigmented macule. The risk is a tethered cord syndrome that can lead to severe complication. The treatment is either surgery or expectation.

Predictive value of cardiovascular parameters in twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate the prognostic value of the Children's Hospital Of Philadelphia (CHOP) cardiovascular score and the modified myocardial performance index (MPI), in determining the risk of recipient fetal loss in twin-to-twin transfusion syndrome (TTTS).

METHODS

This cohort study was based on data collected prospectively from 105 pregnancies complicated by TTTS (Quintero stages I-IV) and treated with laser photocoagulation between May 2008 and February 2013. Fetuses underwent detailed anatomical and Doppler ultrasonography with cardiac assessment as part of routine care. CHOP score and right MPI were calculated and cut-offs selected using receiver-operating characteristics curve analysis. These were compared according to loss of recipient fetus, using univariate and multivariate logistic regression. The correlation between CHOP score, MPI and Quintero stage was determined and we investigated differences in MPI before and after laser coagulation in a cohort of 90 recipient fetuses.

RESULTS

Rates of recipient fetal loss were significantly higher when the CHOP score was ≥ 3 (39.5% vs 12.9%, P = 0.002) and when MPI z-score was > 1.645 (34.5% vs 10.6%, P = 0.004). After adjustment for Quintero stage, the risk of recipient fetal loss remained significantly higher when the CHOP score was ≥ 3 (odds ratio, 3.09; 95% CI, 1.035-9.21). There was a positive correlation between CHOP score, MPI and Quintero stage. MPI was significantly lower after compared with before laser coagulation.

CONCLUSION

CHOP score and MPI are predictors of recipient fetal loss in TTTS and may be used to supplement Quintero's classification.

Fetoscopic laser coagulation for twin-twin transfusion syndrome before 17 weeks' gestation: laser data, complications and neonatal outcome

OBJECTIVE

To compare laser data, complications and neonatal outcome in pregnancies that undergo 'early' (≤ 17 weeks' gestation) fetoscopic laser ablation of placental vascular anastomoses for twin-twin transfusion syndrome (TTTS) with those from 'conventional' cases treated after 17 weeks.

METHODS

This was a cohort study of data collected prospectively between January 2004 and December 2012. We included monochorionic diamniotic twin pregnancies complicated by TTTS and treated by fetoscopic laser coagulation. Pregnancies were grouped according to laser treatment ≤ 17 gestational weeks or > 17 weeks and obstetric and neonatal outcomes were compared between groups.

RESULTS

A total of 178 pregnancies with TTTS underwent laser therapy: 40 at or before 17 weeks and 138 after 17 weeks. There was no statistically significant difference between these two groups with respect to the rate of preterm prelabor rupture of membranes (PPROM), gestational age at PPROM and rate of PPROM occurring in the 7 days following fetoscopic laser coagulation. In the early group, the interval between performing fetoscopic laser coagulation and the time of delivery was significantly longer (104 days vs 74 days, P=0.0002) and the delivery rate within 7 days of laser treatment was significantly lower (2.5% vs 15.9%, P=0.026). There was no significant difference between the two groups with regard to the rates of pregnancy without live birth (15.4% vs 15.4%, P=0.993), with one live birth (84.6% vs 84.6%, P=0.993) and with two live births (64.1% vs 58.1%, P=0.500).

CONCLUSION

In the event of early TTTS, fetoscopic laser coagulation is technically feasible before 17 gestational weeks and obstetric and neonatal outcomes are comparable with those in cases of laser treatment performed after 17 weeks.

Efficacy and safety of labour induction in patients with a single previous caesarean section: a proposal for a clinical protocol

PURPOSE

To evaluate the efficacy and safety of induction in women with a single prior Caesarean section.

METHODS

This was a cohort study in which we included all singleton pregnancies in patients with a single prior Caesarean who delivered between 2007 and 2012. Methods of induction were ocytocic infusion plus amniotomy (if Bishop score ≥6) or insertion of a Foley catheter (Bishop <6).

RESULTS

Of the 2,075 patients included, 806 (38.8 %) had an elective repeat Caesarean, 1,045 (50.4 %) went into spontaneous labour, 89 (4.3 %) were induced by artificial rupture of the membranes and infusion of ocytocics and 135 (6.5 %) were induced using a Foley catheter. Rates of vaginal delivery were 79.2, 79.8 and 43.7 %, respectively. Six cases of uterine rupture were reported in the group of patients who went into spontaneous labour. There was no difference between groups with regard to neonatal morbidity. On multivariate analysis, risk factors for Caesarean delivery were macrosomia (OR 2.04, 95 % CI 1.31-3.18) and induction by Foley catheter (OR 3.73, 95 % CI 2.47-5.62); protective factors were previous vaginal delivery (OR 0.41, 95 % CI 0.29-0.57) and cervical dilatation (OR 0.84, 95 % CI 0.78-0.91).

CONCLUSIONS

Uterine induction after a single Caesarean section with ocytocic infusion and amniotomy where the cervix is favourable does not appear to entail any significant added risk in terms of maternal or foetal morbidity. Foley catheter induction is a reasonable option if the cervix is not ripe.

NOTIZEN: Bildung und Reaktion Si-fluorierter 1.3.5-Trisila-cyclohexane / Formation and Reactions of Si-fluorinated 1,3,5-Trisilacyclohexanes

The reaction of 1,3,5-Trisilacyclohexanes containing Si—F and C—Cl groups and CH3MgCl starts with methylation of the Si—F group (in contrast to the reactions of the corresponding Si—Cl containing derivatives). At a certain degree of methylation a ring contraction starts at the C—Cl group.

Bildung siliciumorganischer Verbindungen

Die thermische Bildung von Siliciumwasserstoffradikalen und Η-Atomen aus entsprechenden Siliciumwasserstoffverbindungen ermöglicht Reaktionen mit Kohlenwasserstoffen, die zur Bildung von Si-C-Bindungen führen. Unter den Siliciumverbindungen werden das Hydrolysenprodukt des CaSi, das Siloxen und das SiH4 für die Untersuchung ausgewählt. Der Reaktionsbeginn liegt bei der Zersetzungstemperatur der verschiedenen Siliciumwasserstoffverbindungen. Unter den Reaktionsprodukten finden sich einfache siliciumorganische Verbindungen, die sich formal vom SiH4 durch Austauschen eines oder mehrerer Η-Atome durch organische Gruppen ableiten, Stoffe mit mehreren Siliciumatomen im Molekül in Form von Si-Si-Bindungen und schließlich feste polymere Produkte, unter denen die Verbindung [SiCH3]x isoliert wurde.

Bildung siliciumorganischer Verbindungen

Wie früher kurz mitgeteilt1, finden mit beginnender thermischer Zersetzung vom SiH4 Umsetzungen mit chlorierten Kohlenwasserstoffen statt. Bei der Reaktion von SiH4 mit Vinylchlorid entstehen um 400° C gasförmige, leichtflüchtige, ölartige und feste siliciumorganische Stoffe. Unter den leichtflüchtigen Verbindungen wurden bisher CH3SiHCl2, SiCl4, (CH3)2SiCl2, C2H5SiCl3 und (C2H5)2SiCl2 aufgefunden. In den höhersiedenden Verbindungen ist teilweise Chlor an Kohlenstoff gebunden. Je nach den Reaktionsbedingungen bilden sich außerdem Verbindungen mit mehr als einem Siliciumatom im Molekül, wobei die Siliciumatome durch Si-Si-Bindungen verknüpft sind. So wurde z. B. ein zitronengelbes, festes Produkt der Zusammensetzung (Si2ClR)x isoliert. Verlängerung der Reaktionszeit führt unter anderen Stoffen zu höhermolekularen Verbindungen, die nach den ermittelten Eigenschaften nicht mehr aus reinen Si-Si-Bindungen aufgebaut sein können, sondern wenigstens teilweise Si-C-Bindungen in der Kette enthalten müssen.

Notizen: Über die Spaltung der Si—O-Bindung mit LiAlH4 unter Bildung von Siliciumwasserstoff-Verbindungen

Bei dem Versuch, aus Si2OCl6 mit Hilfe von LiAIH4 das Disiloxan Si2OH6 herzustellen wurde festgestellt, daß dieses Produkt praktisch gar nicht gebildet wird, sondern daß in stürmisch verlaufender Reaktion als flüchtiges Reaktionsprodukt das SiH4 entsteht. Neben der bekannten Reaktion der Si-CI-Bindung mit LiAIH4 zu Si-H 1 hat sich in unserem Fall die Spaltung der im Si2OCl6 vorhandenen Si—O—Si-Bindung unter Ausbildung einer Si-H-Bindung vollzogen.

Eine ausführliche Veröffentlichung erfolgt demnächst an anderer Stelle.

Prediction of spontaneous preterm delivery in singleton pregnancies: where are we and where are we going? A review of literature

Prematurity is the chief cause of neonatal morbidity and mortality. The objective of this study is to review the different methods for predicting preterm delivery in asymptomatic pregnant women and in situations of threatened preterm delivery. A search of the PubMed/Medline database was carried out for the years 1980-2012. We included studies for predicting preterm birth in asymptomatic and symptomatic patients. Models for predicting preterm delivery based on maternal factors, cervical length and obstetric history in first trimester of pregnancy is a valuable avenue of research. Nevertheless, prediction accuracy still needs to be improved. In the second and third trimesters, routine digital vaginal examination is of no value in asymptomatic women. Echography of the cervix is not useful except in patients with a history of late miscarriage or preterm delivery in order to offer them a preventive treatment. In symptomatic women, the combination of digital vaginal examination, cervical echography and fibronectin gives the best predictive results. Electromyography of the uterus and elastography of the cervix are interesting avenues for future research. Identifying patients at risk of preterm delivery should be considered differently at each stage of pregnancy.

[Abruptio placentae. Diagnosis, management and maternal-fetal prognosis: a retrospective study of 100 cases]

OBJECTIVES

To update knowledge on placental abruption because there are few recent series published although the perinatal care has progressed.

PATIENTS AND METHODS

A retrospective observational study has been conducted on 100 consecutive cases of abruptio placentae, occurring from January 2008 to June 2011, in the two maternity units of the University Hospital of Strasbourg (France).

RESULTS

One hundred and five births among which five twin pregnancies were included. Clinical context was evident in 91% of cases, but the classic clinical triad was present in only 4% of cases. Clots were found at immediate placenta examination in 77% of cases. Pathological diagnosis was directly in accordance with clinical diagnosis in half the cases. Mean date of childbirth was 33 weeks of amenorrhea and 6 days. Sixty-seven patients gave birth prematurely. Among them, 50 patients delivered before 34 weeks. Sixty caesareans were performed in emergency before labor, including 47 with general anesthesia. Twelve patients had post-partum haemorrhage and ten coagulation disorders. There was no maternal death. Perinatal mortality was 19% with 13 fetal deaths in utero (12.4%), four children born in an apparent death state with resuscitation failure (3.8%) and three neonatal deaths (2.8%).

DISCUSSION AND CONCLUSION

Placental abruption is a serious and unpredictable situation. Joint medical care of obstetricians and intensivists is often required. Perinatal mortality mainly occurs in utero.

Rac1 modulates acute and subacute genotoxin-induced hepatic stress responses, fibrosis and liver aging

To investigate the importance of the Ras-homologous GTPase Rac1 for the hepatic response to genotoxic insults and liver aging, rac1 was deleted in liver of mice by Mx1-Cre-based recombination. Knockout of rac1 caused complex changes in basal as well as doxorubicin and ionizing radiation-induced mRNA expression of various genotoxic stress response-related genes, including hspa1b, rad51, wrn and xpc. Rac1 deletion protected the liver from acute toxicity following doxorubicin treatment. Moreover, the level of S139 phosphorylated histone H2AX (γH2AX), which is indicative of DNA damage, and mRNA expression of pro-inflammatory (IL-6) and pro-fibrotic (CTGF, TGFβ, αSMA) factors were mitigated in rac1 knockout animals. By contrast, lack of rac1 promoted subacute hepatotoxicity, which was determined 3 weeks after injection of multiple low doses of doxorubicin by assaying the γH2AX level, mitotic index and pro-fibrotic gene expression. Regarding ionizing radiation, rac1 deficiency had no major effects on DNA damage induction or acute pro-inflammatory and pro-fibrotic stress responses. Mice lacking hepatic rac1 for extended period of time (15 months) revealed increased mRNA expression of fibrosis-related factors (CTGF, TGFβ, collagen, MMP1) and fibrotic tissue remodeling. In addition, protein expression of the senescence marker p16 was enhanced in the absence of rac1. Taken together, the data provide evidence that Rac1 is required for doxorubicin-induced DNA damage induction. It is also involved in both the acute and delayed inflammatory and fibrotic stress response in the liver following doxorubicin, but not ionizing radiation, treatment and, furthermore, protects against endogenous liver aging.

[Management of patients with a history of late abortion or very premature delivery]

Patients have a very late abortion or premature delivery in 2-3 % of pregnancies. Management in a subsequent pregnancy should seek an infection, a fetal cause (aneuploidy, malformation syndrome, intrauterine death) or vascular pathology (preeclampsia, IUGR, intrauterine death). In women with a late abortion or very premature childbirth history, several preventive treatments of prematurity are now available. The main cause of prematurity is ascending infection from the vagina. Cerclage or pessary is designed to better isolate the uterine cavity. Their effectiveness has been validated in patients for whom the repeated measurement of cervical length by transvaginal ultrasound shows a cervical length <25mm. Early pregnancy vaginosis and treatment with Dalacin(®) seem to significantly reduce the risk of prematurity. Finally, the routine administration of intramuscular or vaginal progesterone at the beginning of the 2(nd) quarter also proved effective in several randomized studies.

Inhibition of Rac1 signaling by lovastatin protects against anthracycline-induced cardiac toxicity

Normal tissue damage limits the efficacy of anticancer therapy. For anthracyclines, the clinically most relevant adverse effect is cardiotoxicity. The mechanisms involved are poorly understood and putative cardioprotectants are controversially discussed. Here, we show that the lipid-lowering drug lovastatin protects rat H9c2 cardiomyoblasts from doxorubicin in vitro. Protection by lovastatin is related to inhibition of the Ras-homologous GTPase Rac1. It rests on a reduced formation of DNA double-strand breaks, resulting from the inhibition of topoisomerase II by doxorubicin. Doxorubicin transport and reactive oxygen species are not involved. Protection by lovastatin was confirmed in vivo. In mice, lovastatin mitigated acute doxorubicin-induced heart and liver damage as indicated by reduced mRNA levels of the pro-fibrotic cytokine connective tissue growth factor (CTGF) and pro-inflammatory cytokines, respectively. Lovastatin also protected from doxorubicin-provoked subacute cardiac damage as shown by lowered mRNA levels of CTGF and atrial natriuretic peptide. Increase in the serum concentration of troponin I and cardiac fibrosis following doxorubicin treatment were also reduced by lovastatin. Whereas protecting the heart from harmful doxorubicin effects, lovastatin augmented its anticancer efficacy in a mouse xenograft model with human sarcoma cells. These data show that statins lower the incidence of cardiac tissue injury after anthracycline treatment in a Rac1-dependent manner, without impairing the therapeutic efficacy.

Lovastatin causes sensitization of HeLa cells to ionizing radiation‐induced apoptosis by the abrogation of G2 blockage

PURPOSE

To investigate the effect of inhibition of Ras/Rho-regulated signalling by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on radiation-induced cell killing and apoptosis.

MATERIALS AND METHODS

Different human cell lines were pretreated or not with lovastatin before exposure to gamma-rays. Afterwards, radiation-induced cell killing, formation and repair of double-strand breaks, activation of radiation-inducible signal mechanisms (i.e. p53, p21, extracellular-signal-related kinase (ERK), NF-kappaB), changes in cell cycle progression and apoptosis were analysed.

RESULTS

As shown by a colony formation assay, lovastatin sensitized HeLa cells to gamma-radiation-induced cell killing. The lovastatin effect was cell-type specific. Neither the level of gamma-ray-induced double-strand breaks nor its repair were affected by lovastatin. Sensitization was independent of p53/p21Waf1- and NF-kappaB-related mechanisms. Radiation-stimulated activation of ERKs was attenuated by lovastatin. Cell cycle analyses revealed that the level of gamma-ray-induced G2 blockage was not affected by lovastatin. However, as analysed up to 72 h after irradiation, lovastatin pretreated cells showed an accelerated abrogation of G2 blockage as compared with the control. G2 abrogation is paralleled by an increase in the frequency of apoptotic and necrotic cells.

CONCLUSIONS

The data show that lovastatin can render human cells more sensitive to the cytotoxic effect of gamma-rays. This is related to abrogation of G2 blockage and a concomitant increase in apoptotic/necrotic cell death.

Progression of breast tumors is accompanied by a decrease in expression of the Rho guanine exchange factor Tiam1

In this study, we investigated the expression level of Ras-homologous (Rho) GTPases and the Rho guanine exchange factor (GEF) T-cell lymphoma invasion and metastasis 1 (Tiam1) in breast tumor specimens (n=106) by immunohistochemistry. Rho and Rho-GEF expression scores were compared to clinically established diagnostic and prognostic parameters. We found that RhoA and RhoB scores slightly increased with tumor grade, whereas the Rac1 score remained unaffected. The most significant effects were observed for the Rac1-specific GEF Tiam1. Tiam1 expression scores significantly decreased with the increase in tumor grade, tumor spreading and proliferation. Furthermore, Tiam1 expression was inversely related to the plasminogen activator inhibitor (PAI-1) and estrogen receptor (ER) expression but not the progesterone receptor (PR) and urokinase plasminogen activator (uPA). A low Tiam1 expression was associated with p53 positivity without being related to HER2/neu status. The data show that Tiam1 expression decreases with the progression of breast carcinomas and is inversely associated with several established breast tumor markers. Therefore, we suggest that Tiam1 counteracts the progression of breast carcinomas and is suitable as a novel breast tumor marker.