Dynamic interactions and Ca2+-binding modulate the holdase-type chaperone activity of S100B preventing tau aggregation and seeding

The microtubule-associated protein tau is implicated in the formation of oligomers and fibrillar aggregates that evade proteostasis control and spread from cell-to-cell. Tau pathology is accompanied by sustained neuroinflammation and, while the release of alarmin mediators aggravates disease at late stages, early inflammatory responses encompass protective functions. This is the case of the Ca²⁺-binding S100B protein, an astrocytic alarmin which is augmented in AD and which has been recently implicated as a proteostasis regulator, acting over amyloid β aggregation. Here we report the activity of S100B as a suppressor of tau aggregation and seeding, operating at sub-stoichiometric conditions. We show that S100B interacts with tau in living cells even in microtubule-destabilizing conditions. Structural analysis revealed that tau undergoes dynamic interactions with S100B, in a Ca²⁺-dependent manner, notably with the aggregation prone repeat segments at the microtubule binding regions. This interaction involves contacts of tau with a cleft formed at the interface of the S100B dimer. Kinetic and mechanistic analysis revealed that S100B inhibits the aggregation of both full-length tau and of the microtubule binding domain, and that this proceeds through effects over primary and secondary nucleation, as confirmed by seeding assays and direct observation of S100B binding to tau oligomers and fibrils. In agreement with a role as an extracellular chaperone and its accumulation near tau positive inclusions, we show that S100B blocks proteopathic tau seeding. Together, our findings establish tau as a client of the S100B chaperone, providing evidence for neuro-protective functions of this inflammatory mediator across different tauopathies.

The calcium binding protein S100B is an abundantly expressed protein in the brain and has neuro-protective functions by inhibiting Aβ aggregation and metal ion toxicity. Here, the authors combine cell biology and biochemical experiments with chemical kinetics and NMR measurements and show that S100B protein is an extracellular Tau chaperone and further characterize the interactions between S100B and Tau.

[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.

[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.

Lovastatin protects human endothelial cells from the genotoxic and cytotoxic effects of the anticancer drugs doxorubicin and etoposide

BACKGROUND AND PURPOSE

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are frequently used lipid-lowering drugs. Moreover, they exert pleiotropic effects on cellular stress responses and death. Here, we analysed whether lovastatin affects the sensitivity of primary human endothelial cells (HUVEC) to the anticancer drug doxorubicin.

EXPERIMENTAL APPROACH

We investigated whether pretreatment of HUVEC with low dose of lovastatin influences the cellular sensitivity to doxorubicin. To this end, cell viability, proliferation and apoptosis as well as DNA damage-triggered stress response were analysed.

KEY RESULTS

Lovastatin reduced the cytotoxic potency of doxorubicin in HUVEC. Lovastatin attenuated the doxorubicin-induced increase in p53 as well as activation of checkpoint kinase (Chk-1) and stress-activated protein kinase/c-Jun-N-terminal kinase (SAPK/JNK). Acquired doxorubicin resistance was independent of alterations in doxorubicin efflux and cell cycle progression. Also, doxorubicin-triggered production of reactive oxygen species (ROS) and formation of oxidative DNA lesions remained unaffected by lovastatin. However, lovastatin impaired DNA strand break formation induced by doxorubicin. Notably, lovastatin also conferred cross-resistance to the cytotoxic and genotoxic effects of etoposide, indicating that lovastatin shields topoisomerase II against poisons.

CONCLUSIONS AND IMPLICATIONS

Based on these data, we suggest that lovastatin-mediated resistance to topoisomerase II inhibitors is due to a reduction in DNA damage and, hence, it attenuates stress responses leading to cell death that are triggered by DNA damage. Therefore, lovastatin might be useful clinically for alleviating side-effects of anticancer therapies that include topoisomerase II inhibitors.

„Schlaf-Wach-Schlaf“-Technik zur CS Wachkraniotomie

Awake craniotomy in tumor and epilepsy surgery or for the implantation of electrodes for deep brain stimulation requires specific anesthesiological strategies. Propofol allows for quick emergence and has little effect on the respiratory function of the usually spontaneously breathing patient. Pain control may be instituted by hemiscalp block for trepanation or local infiltration for deep brain electrode implantation. In addition, low dose remifentanil is recommended for trepanation (i.e. tumor or epilepsy surgery). The airway may be secured by an ordinary Magill tube placed transnasally with its tip underneath the epiglottis. To protect the patient against vomiting an adequate antiemetic prophylaxis is required.

Key Bacterial Multi-Centered Metal Enzymes Involved in Nitrate and Sulfate Respiration

Many essential life processes, such as photosynthesis, respiration, nitrogen fixation, depend on transition metal ions and their ability to catalyze multi-electron redox and hydrolytic transformations. Here we review some recent structural studies on three multi-site metal enzymes involved in respiratory processes which represent important branches within the global cycles of nitrogen and sulfur: (i) the multi-heme enzyme cytochrome c nitrite reductase, (ii) the FAD, FeS-enzyme adenosine-5'-phosphosulfate reductase, and (iii) the siroheme, FeS-enzyme sulfite reductase. Structural information comes from X-ray crystallography and spectroscopical techniques, in special cases catalytically competent intermediates could be trapped and characterized by X-ray crystallography.

Growth and structure of α-lactalbumin nanotubes

Partial hydrolysis of α-lactalbumin by a protease fromBacillus licheniformisunder appropriate conditions leads to the formation of nanotubular structures. The growth of α-lactalbumin nanotubes and their dimensions were analysed using transmission electron microscopy, static light scattering and small-angle X-ray scattering. The scattering data were fitted using a model describing the growth of the tubes and using the form factor of a hollow tube. The cylinder diameter was calculated to be 19.9 (2) nm and the cavity diameter 8.7 (7) nm. The elongation rate of the nanotubes was about 10 nm min−1under the experimental conditions.

Eine faktorielle Studie von 6 Interventionen zur Vermeidung von �belkeit und Erbrechen nach Narkosen

BACKGROUND

Untreated, one third of patients who undergo surgery will have postoperative nausea and vomiting. Although many trials have been conducted, the relative benefits of prophylactic antiemetic interventions given alone or in combination remain unknown.

METHODS

In a randomized, controlled trial of factorial design, 5,199 patients at high risk for postoperative nausea and vomiting were randomly assigned to 1 of 64 possible combinations of 6 prophylactic interventions: 1) 4 mg of ondansetron or no ondansetron; 2) 4 mg of dexamethasone or no dexamethasone; 3) 1.25 mg of droperidol or no droperidol; 4) propofol or a volatile anesthetic; 5) nitrogen or nitrous oxide; 6) remifentanil or fentanyl. The primary aim parameter was nausea and vomiting within 24 h after surgery, which was evaluated blindly.

RESULTS

Ondansetron, dexamethasone, and droperidol each reduced the risk of postoperative nausea and vomiting by about 26%, propofol reduced the risk by 19%, and nitrogen by 12%. The risk reduction with both of these agents (i.e., total intravenous anesthesia) was thus similar to that observed with each of the antiemetics alone. All the interventions acted independently of each other and independently of the patients' baseline risk. Consequently, the relative risks associated with the combined interventions could be estimated by multiplying the relative risks associated with each intervention. However, absolute risk reduction was a critical function of patients' baseline risk.

CONCLUSIONS

Because antiemetic interventions are similarly effective and act independently, the safest or least expensive should be used first. Prophylaxis is rarely warranted in low-risk patients, moderate-risk patients may benefit from a single intervention, and multiple interventions should be reserved for high-risk patients.